**Meet the editor**

Dr. Ivan Zhu has highly specialized expertise in biological wastewater treatment, membrane applications to industrial and municipal water and wastewater treatment, flocs and biofilm characterization in terms of microbial community distribution and extracellular polymeric substances, and membrane fouling characterization. He has applied his extensive knowledge of separation

processes to the evaluation and design of water and wastewater chemical/ biological treatment processes. Dr. Zhu worked at Xylem Water Solutions, where he gained extensive experience in drinking water treatment, wastewater tertiary treatment, denitrification, biological active filtration, ozone-enhanced biofiltration, and dissolved air flotation. Presently, he is working at Evoqua Water Technologies as an applications engineer for integrated industrial solutions for water and wastewater treatment. He holds a bachelor's degree from Shanghai Jiaotong University in Shanghai, China, and master's and doctoral degrees from the University of Toronto, Ontario, Canada.

Contents

**Preface VII**

Naeem Khan

**South Africa 55**

Markus R. Zehringer

la Iglesia

Chapter 1 **Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects on Plant Health 1**

Chapter 2 **Treatment of Sewage (Domestic Wastewater or Municipal**

Chapter 3 **The Importance of Media in Wastewater Treatment 35** Ewa Dacewicz and Krzysztof Chmielowski

Chapter 4 **A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study of Limpopo Province,**

Kudakwashe K. Shamuyarira and Jabulani R. Gumbo

Chapter 6 **Municipal Sewage Sludge Variability: Biodegradation through**

David Alves Comesaña, Iria Villar Comesaña and Salustiano Mato de

Chapter 5 **Fate of Radiopharmaceuticals in the Environment 77**

**Composting with Bulking Agent 97**

**Wastewater) and Electricity Production by Integrating Constructed Wetland with Microbial Fuel Cell 17**

Maitreyie Narayan, Praveen Solanki and Rajeev Kumar Srivastava

## Contents

**Preface XI**


Preface

worldwide in wastewater treatment.

po Province, South Africa

Wastewater treatment is a process used to convert wastewater into an effluent (outflowing of water to a receiving body of water) that can be either returned to the water cycle with minimal impact on the environment or directly reused. Climate change, population growth, and water scarcity have contributed to a growing demand for sustainable management of water resources. The treatment of wastewater is part of sanitation. Sanitation also includes the management of human and solid waste, as well as storm-water (drainage) management. By-products from wastewater treatment plants, such as screenings, grit, and sewage sludge, may also be treated in a wastewater treatment plant. Municipalities and industries are now faced with the prospect of treating, conserving, or deep polishing water and wastewater be‐ fore it is used for other purposes, or discharged to rivers, lakes, and other receiving water bodies. Conventional processes and technologies, such as screening, degritting, clarification and sedimentation, biological processes of suspended growth and fixed biofilm systems, media filtration, and chlorine disinfection, have been well developed and widely applied

Rather than reviewing and discussing conventional treatment processes, this book provides

1. Natural ecological remediation and reuse of municipal wastewater in agriculture 2. Treatment of wastewater and electricity production by integrating constructed

4. A review of trace metals in municipal sewage and sludge: a case study of Limpo‐

While extensive research had been conducted on conventional wastewater treatment, this book is oriented to some interesting processes and selected applications, such as natural eco‐ logical remediation and the integration of treatment of wastewater and electricity production. It is anticipated that this book will shed light on the future direction of research and innovation. Finally, during the course of editing and compiling this book, extensive support and guid‐ ance were received from Ms. Danijela Sakic, publishing process manager. The editor would

**Ivan X. Zhu**

Evoqua Water Technologies Warrendale, PA, USA

a unique aspect of wastewater treatment and sludge disposal. Topics will include:

3. The application of various media materials in wastewater treatment

6. Biodegradation of sludge through composting with bulking agent

wetland coupled with microbial fuel cell (CW-MFC)

5. The fate of radiopharmaceuticals in the environment

like to express deep appreciation and gratefulness for her support.

## Preface

Wastewater treatment is a process used to convert wastewater into an effluent (outflowing of water to a receiving body of water) that can be either returned to the water cycle with minimal impact on the environment or directly reused. Climate change, population growth, and water scarcity have contributed to a growing demand for sustainable management of water resources. The treatment of wastewater is part of sanitation. Sanitation also includes the management of human and solid waste, as well as storm-water (drainage) management. By-products from wastewater treatment plants, such as screenings, grit, and sewage sludge, may also be treated in a wastewater treatment plant. Municipalities and industries are now faced with the prospect of treating, conserving, or deep polishing water and wastewater be‐ fore it is used for other purposes, or discharged to rivers, lakes, and other receiving water bodies. Conventional processes and technologies, such as screening, degritting, clarification and sedimentation, biological processes of suspended growth and fixed biofilm systems, media filtration, and chlorine disinfection, have been well developed and widely applied worldwide in wastewater treatment.

Rather than reviewing and discussing conventional treatment processes, this book provides a unique aspect of wastewater treatment and sludge disposal. Topics will include:


While extensive research had been conducted on conventional wastewater treatment, this book is oriented to some interesting processes and selected applications, such as natural eco‐ logical remediation and the integration of treatment of wastewater and electricity production. It is anticipated that this book will shed light on the future direction of research and innovation.

Finally, during the course of editing and compiling this book, extensive support and guid‐ ance were received from Ms. Danijela Sakic, publishing process manager. The editor would like to express deep appreciation and gratefulness for her support.

> **Ivan X. Zhu** Evoqua Water Technologies Warrendale, PA, USA

**Chapter 1**

**Provisional chapter**

**Natural Ecological Remediation and Reuse of Sewage**

**Natural Ecological Remediation and Reuse of Sewage** 

In rural and urban areas of most emergent countries, the application of sewerage and wastewater for irrigation is a regular practice. In these areas, polluted water is often the only supply of water for irrigation. The use of wastewater for crop growth is a centuries old practice that is getting renewed attention due to rising shortage of freshwater resources in many arid and semiarid regions of the globe. Wastewater is extensively used as an inexpensive substitute to conservative irrigation water, supporting livelihoods and generating significant value to the agriculture of urban and periurban areas in spite of the associated health and environmental risks. Water is becoming an increasingly limited resource in many dried and partially dried regions of the world due to which planners are being forced to think about other sources of water that might be used inexpensively and efficiently to encourage additional progress. It is concluded that sewage water is the richest source of micro- and macronutrients and this aims for the better growth of plants. However, sewage should be treated prior to its reuse for agriculture in order to reduce

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.75455

**Water in Agriculture and Its Effects on Plant Health**

**Water in Agriculture and Its Effects on Plant Health**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

the risks of harmful effects on human and animal health.

**Keywords:** sewage water, developing countries, nutrients, chemical fertilizer

In rural and urban areas of most emergent countries, the application of sewerage and wastewater for irrigation is a regular practice. In these areas, polluted water is often the only supply of water for irrigation. Yet small farmers often prefer wastewater where other water sources are also available because wastewater has high nutrient content which may reduce or even eliminate the need for other costly chemical fertilizers [1]. The use of wastewater for

http://dx.doi.org/10.5772/intechopen.75455

Naeem Khan

Naeem Khan

**Abstract**

**1. Introduction**

#### **Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects on Plant Health Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects on Plant Health**

DOI: 10.5772/intechopen.75455

#### Naeem Khan Naeem Khan

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.75455

#### **Abstract**

In rural and urban areas of most emergent countries, the application of sewerage and wastewater for irrigation is a regular practice. In these areas, polluted water is often the only supply of water for irrigation. The use of wastewater for crop growth is a centuries old practice that is getting renewed attention due to rising shortage of freshwater resources in many arid and semiarid regions of the globe. Wastewater is extensively used as an inexpensive substitute to conservative irrigation water, supporting livelihoods and generating significant value to the agriculture of urban and periurban areas in spite of the associated health and environmental risks. Water is becoming an increasingly limited resource in many dried and partially dried regions of the world due to which planners are being forced to think about other sources of water that might be used inexpensively and efficiently to encourage additional progress. It is concluded that sewage water is the richest source of micro- and macronutrients and this aims for the better growth of plants. However, sewage should be treated prior to its reuse for agriculture in order to reduce the risks of harmful effects on human and animal health.

**Keywords:** sewage water, developing countries, nutrients, chemical fertilizer

#### **1. Introduction**

In rural and urban areas of most emergent countries, the application of sewerage and wastewater for irrigation is a regular practice. In these areas, polluted water is often the only supply of water for irrigation. Yet small farmers often prefer wastewater where other water sources are also available because wastewater has high nutrient content which may reduce or even eliminate the need for other costly chemical fertilizers [1]. The use of wastewater for

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

crop growth is a centuries old practice in many arid and semi-arid regions of the globe [2]. Farmers often have no alternative, so they depend on unprocessed wastewater as there is no wastewater collection and treatment and freshwater is either out of stock or too expensive [3, 4]. The uses of wastewater in agriculture create key risks to the health of the community due to chemical and microbial contaminants. Wastewater use can also produce ecological risks in terms of soil and groundwater contamination. Irrigation with wastewater can have a number of benefits and environmental applications if appropriately planned, implemented, and managed [5].

Many wastewater irrigators are generally landless people who are not land-owning farmers; they lease small plots to grow income-generating crops like vegetables that flourish when watered with nutrient-rich sewage [6]. Across Africa, Asia, and Latin America, the microeconomies of sewage water support a large number of low-income individuals. Stoppage or overregulation of these practices could take away the only income source of numerous landless people. However, in these countries, the sewage water is not processed before use for irrigation. Wastewater treatment is generally carried out in developed countries, where major investment on wastewater treatment has been made over the past 40–50 years in order to achieve high treatment levels. Most sewage water is treated in North America, usually up to secondary and, in numerous cases, up to tertiary levels [7]. The USA has made improvement as a result of a financial support program in which 56 billion USD were allocated to local governments from 1972 to 1989 to construct secondary management amenities, but they changed these grants by state revolving funds for loans to municipalities [8].

Sewage treatment (**Figure 1**) is regarded as vital in affluent countries in order to guard human health and avoid pollution of rivers and lakes, but for the majority of developing countries, this solution is too costly. Therefore, in case of developing countries, application of wastewater in agriculture is a more reasonable option and economically sound than uninhibited removal of industrial and municipal effluents addicted to lakes and streams [4]. The sewage flows to a downstream location that is hazardous due to which the population inside the streams and water sources are at risk. Such risks can be decreased or proscribed by wastewater treatment in a wastewater treatment plant consisting of physical, chemical, and biological processes [9]. Wastewater treatment may also produce sludge, which is also risky for health because it is a polluted by-product and requires secure managing and removal [10].

Use of sewage water for irrigation has many applications (**Figure 2**), including crop irrigation, aquaculture, irrigation of landscape, and fake groundwater recharge [11]. This is one of the longest and well-known traditions in most parts of the world. According to estimation, the total area under wastewater irrigation is about 20 million hectares throughout the world [12]. It has been found that the maximum number of crop plants viz. lettuce, mangoes, tomatoes, and coconut are irrigated with sewage water, and a large quantity of this water is unprocessed [12]. Sewage and industrial wastewater is commonly used to water farming fields in developing countries including Pakistan [13, 14]. Sewage irrigation has proven beneficial effects on plant health and soil quality in countries having low water resources

such as Mediterranean Basin and the Middle East, for instance, Bahrain, Cyprus, Kuwait, Malta, Israel, Qatar, Oman, Saudi Arabia, and the United Arab Emirates [15]. Numerous investigations have reported positive impacts of sewage irrigation on plants and soil properties. Wastewater can be used as an important plant nutrient source for soils with low fertility. Municipal wastewater could possibly be used for crop irrigation with negligible environmental concerns if it does not contain excessive heavy metals. Use of wastewater for irrigation purposes can decrease the necessity for fertilizers [16]. For these reasons, both treated and untreated wastewaters have been used for irrigation worldwide. Earlier studies,

**Figure 2.** Impacts of sewage water irrigation on plants and freshwater reservoirs.

**Figure 1.** Ecological sewage treatment (http://ingienous.com/sectors/the-environment/eliminating-waste-and-inefficiency/

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects…

http://dx.doi.org/10.5772/intechopen.75455

3

sewage-treatment-via-bionutrient-recycling/).

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects… http://dx.doi.org/10.5772/intechopen.75455 3

crop growth is a centuries old practice in many arid and semi-arid regions of the globe [2]. Farmers often have no alternative, so they depend on unprocessed wastewater as there is no wastewater collection and treatment and freshwater is either out of stock or too expensive [3, 4]. The uses of wastewater in agriculture create key risks to the health of the community due to chemical and microbial contaminants. Wastewater use can also produce ecological risks in terms of soil and groundwater contamination. Irrigation with wastewater can have a number of benefits and environmental applications if appropriately planned, implemented,

Many wastewater irrigators are generally landless people who are not land-owning farmers; they lease small plots to grow income-generating crops like vegetables that flourish when watered with nutrient-rich sewage [6]. Across Africa, Asia, and Latin America, the microeconomies of sewage water support a large number of low-income individuals. Stoppage or overregulation of these practices could take away the only income source of numerous landless people. However, in these countries, the sewage water is not processed before use for irrigation. Wastewater treatment is generally carried out in developed countries, where major investment on wastewater treatment has been made over the past 40–50 years in order to achieve high treatment levels. Most sewage water is treated in North America, usually up to secondary and, in numerous cases, up to tertiary levels [7]. The USA has made improvement as a result of a financial support program in which 56 billion USD were allocated to local governments from 1972 to 1989 to construct secondary management amenities, but they changed

Sewage treatment (**Figure 1**) is regarded as vital in affluent countries in order to guard human health and avoid pollution of rivers and lakes, but for the majority of developing countries, this solution is too costly. Therefore, in case of developing countries, application of wastewater in agriculture is a more reasonable option and economically sound than uninhibited removal of industrial and municipal effluents addicted to lakes and streams [4]. The sewage flows to a downstream location that is hazardous due to which the population inside the streams and water sources are at risk. Such risks can be decreased or proscribed by wastewater treatment in a wastewater treatment plant consisting of physical, chemical, and biological processes [9]. Wastewater treatment may also produce sludge, which is also risky for health because it is a polluted by-product and requires secure managing and

Use of sewage water for irrigation has many applications (**Figure 2**), including crop irrigation, aquaculture, irrigation of landscape, and fake groundwater recharge [11]. This is one of the longest and well-known traditions in most parts of the world. According to estimation, the total area under wastewater irrigation is about 20 million hectares throughout the world [12]. It has been found that the maximum number of crop plants viz. lettuce, mangoes, tomatoes, and coconut are irrigated with sewage water, and a large quantity of this water is unprocessed [12]. Sewage and industrial wastewater is commonly used to water farming fields in developing countries including Pakistan [13, 14]. Sewage irrigation has proven beneficial effects on plant health and soil quality in countries having low water resources

these grants by state revolving funds for loans to municipalities [8].

and managed [5].

2 Sewage

removal [10].

**Figure 1.** Ecological sewage treatment (http://ingienous.com/sectors/the-environment/eliminating-waste-and-inefficiency/ sewage-treatment-via-bionutrient-recycling/).

**Figure 2.** Impacts of sewage water irrigation on plants and freshwater reservoirs.

such as Mediterranean Basin and the Middle East, for instance, Bahrain, Cyprus, Kuwait, Malta, Israel, Qatar, Oman, Saudi Arabia, and the United Arab Emirates [15]. Numerous investigations have reported positive impacts of sewage irrigation on plants and soil properties. Wastewater can be used as an important plant nutrient source for soils with low fertility. Municipal wastewater could possibly be used for crop irrigation with negligible environmental concerns if it does not contain excessive heavy metals. Use of wastewater for irrigation purposes can decrease the necessity for fertilizers [16]. For these reasons, both treated and untreated wastewaters have been used for irrigation worldwide. Earlier studies, carried out in areas irrigated with wastewater over a long period of time, have confirmed improved soil biological activity and nutrient cycling as a result of the resulting input of easily degradable organic material and nutrients [4].

The application of wastewater to cropland and forests is a smart option for disposal because it can improve the physical properties and nutrient content in soils. Wastewater can often contain substantial concentrations of organic and inorganic nutrients, for example, nitrogen and phosphate, which are crucial for crop growth. One possible advantage is that the soil microorganisms have been observed to have increased metabolic activity when a sewage effluent is reused in irrigation [17]. Castro et al. [18] reported that dry and fresh weight, average height, and diameter were significantly higher in treated wastewater-irrigated plants. The highest values were observed in the second crop season. El-Nahhal et al. [18] investigated the effects of sewage water on the growth of Chinese cabbage and found that the sewage water was effective in supplying the necessary nutrients required for the normal growth of plants and noted higher biomass in plants irrigated with wastewater as compared to fresh water. Castro et al. [19] reported significant increase in fresh and dry weights, average height, and diameter of *Lactuca sativa* irrigated with sewage water when compared to control. Alghobar et al. [20] reported improved chemical properties and fertility status of soils irrigated with sewage water. They also found enhanced growth in grass crop after irrigation with sewage water.

Safary and Hajrasoliha [21] carried out experiments on plants irrigated with sewage water and noted that after 7 years of irrigation with sewage significantly enhanced carbon, nitrogen, and phosphorus contents and decreased soil salinity and sodicity. Rattan et al. [22] reported the beneficial effects of sewage effluents when applied to cereals, vegetables, and fodder crops. Singh et al. [23] used sewage water for irrigation of several crop plants including wheat, gram, palak, methi, and berseem. They recorded improvement in physiochemical properties of soil, nutrient stats of soil, and yield of crops as compared to plants irrigated with normal groundwater. Wang et al. [24] also noted that long-term irrigation with sewage water significantly enhanced soil micro- and macronutrient content that in turn enhanced plant growth. Recently, Khan and Bano [25] reported the beneficial effects of sewage irrigation on the total chlorophyll and carotenoids content of maize plant. They also recorded increased nutrient content in plants and soil.

To fully understand the vital issue of wastewater reuse with regard to benefits and mitigate the risks, this chapter was aimed at determining the effects of sewage on the growth parameters of plants and to review the natural ecological and engineered approaches for the treatment of sewage water before its application to irrigation. Regulations of wastewater reuse in different countries are also reviewed and discussed.

#### **2. Natural ecological and engineered sewage treatment**

Sewage treatment (**Figures 3** and **4**) is the process of eradicating microorganism, heavy metal, and other types of contaminants from wastewater. The practice of wastewater treatment varies from one region to another across the world. In developed countries, a centralized aerobic wastewater treatment, consisting of plants, has been carried out for both industrial and domestic wastewater. Sewage treatment using natural ecological approach has been carried out throughout the world because certain terrestrial and aquatic plants have the ability to accrue large quantities of certain metals in their shoots [26]. The use of wetland and aquatic plants, such as

**Figure 4.** Reuse of sewage water for irrigation after treatment.

**Figure 3.** Biological treatment of wastewater for reuse in agriculture. (http://saleemindia.blogspot.com/2017/01/constructed-

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects…

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5

wetlands-for-sewage.html).

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects… http://dx.doi.org/10.5772/intechopen.75455 5

**Figure 3.** Biological treatment of wastewater for reuse in agriculture. (http://saleemindia.blogspot.com/2017/01/constructedwetlands-for-sewage.html).

**Figure 4.** Reuse of sewage water for irrigation after treatment.

carried out in areas irrigated with wastewater over a long period of time, have confirmed improved soil biological activity and nutrient cycling as a result of the resulting input of

The application of wastewater to cropland and forests is a smart option for disposal because it can improve the physical properties and nutrient content in soils. Wastewater can often contain substantial concentrations of organic and inorganic nutrients, for example, nitrogen and phosphate, which are crucial for crop growth. One possible advantage is that the soil microorganisms have been observed to have increased metabolic activity when a sewage effluent is reused in irrigation [17]. Castro et al. [18] reported that dry and fresh weight, average height, and diameter were significantly higher in treated wastewater-irrigated plants. The highest values were observed in the second crop season. El-Nahhal et al. [18] investigated the effects of sewage water on the growth of Chinese cabbage and found that the sewage water was effective in supplying the necessary nutrients required for the normal growth of plants and noted higher biomass in plants irrigated with wastewater as compared to fresh water. Castro et al. [19] reported significant increase in fresh and dry weights, average height, and diameter of *Lactuca sativa* irrigated with sewage water when compared to control. Alghobar et al. [20] reported improved chemical properties and fertility status of soils irrigated with sewage water. They also found enhanced growth in grass crop after irrigation with sewage water.

Safary and Hajrasoliha [21] carried out experiments on plants irrigated with sewage water and noted that after 7 years of irrigation with sewage significantly enhanced carbon, nitrogen, and phosphorus contents and decreased soil salinity and sodicity. Rattan et al. [22] reported the beneficial effects of sewage effluents when applied to cereals, vegetables, and fodder crops. Singh et al. [23] used sewage water for irrigation of several crop plants including wheat, gram, palak, methi, and berseem. They recorded improvement in physiochemical properties of soil, nutrient stats of soil, and yield of crops as compared to plants irrigated with normal groundwater. Wang et al. [24] also noted that long-term irrigation with sewage water significantly enhanced soil micro- and macronutrient content that in turn enhanced plant growth. Recently, Khan and Bano [25] reported the beneficial effects of sewage irrigation on the total chlorophyll and carotenoids content of maize plant. They also recorded increased nutrient content in plants and soil. To fully understand the vital issue of wastewater reuse with regard to benefits and mitigate the risks, this chapter was aimed at determining the effects of sewage on the growth parameters of plants and to review the natural ecological and engineered approaches for the treatment of sewage water before its application to irrigation. Regulations of wastewater reuse in

Sewage treatment (**Figures 3** and **4**) is the process of eradicating microorganism, heavy metal, and other types of contaminants from wastewater. The practice of wastewater treatment varies

easily degradable organic material and nutrients [4].

4 Sewage

different countries are also reviewed and discussed.

**2. Natural ecological and engineered sewage treatment**

from one region to another across the world. In developed countries, a centralized aerobic wastewater treatment, consisting of plants, has been carried out for both industrial and domestic wastewater. Sewage treatment using natural ecological approach has been carried out throughout the world because certain terrestrial and aquatic plants have the ability to accrue large quantities of certain metals in their shoots [26]. The use of wetland and aquatic plants, such as water velvet and duckweed for the removal of contaminants from the sewage water, is considered the most effective method for the removal of heavy metals.

**Rhizofiltration:** It is the removal of pollutants from the contaminated waters by accumulation into plant biomass. Several aquatic species including sharp dock, duckweed, and so on, have been identified and tested for the phytoremediation of heavy metals from the polluted

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects…

Besides these natural ecological treatments, other engineered approaches are also widely carried out worldwide for wastewater treatment to remove pathogen and other harmful sub-

**Oxidation Ponds:** Oxidation ponds are used for reducing the biochemical oxygen demand (BOD) of wastewater. This is a very effective and simple technology, which consists of a ringshaped channel equipped with mechanical aeration devices. The wastewater is screened and

**Anaerobic Ponds:** It is a biological treatment of wastewater in which naturally occurring bacteria are utilized for breaking the biodegradable compounds present in wastewater. These bacteria under anaerobic condition may remove high concentrations of BOD and chemical oxygen demand (COD). The presence of anaerobic bacteria in these ponds break the organic

**Aerobic Ponds:** In aerobic treatment of wastewater, bacteria and algae are used that maintain aerobic condition throughout its depth. The aerobic ponds may be shallow or aerated [43].

**Trickling Filter:** This technique is used to remove or reduce pathogen and level of nitrogen in the wastewater as pathogens present in wastewater may cause serious threats to humans mostly in developing countries of the world. This trickling filter is composed of some porous material like rocks, sledge, or plastic medium having large surface area and permeability. The

**Activated Sludge System:** This is a biological wastewater treatment, which is mainly used for the removal of biodegradable compounds and pathogens present in wastewater. Its efficiency depends on retention time, temperature, pH, and the presence of other biological flora pres-

The World Health Organization (WHO), the US Environmental Protection Agency (USEPA), and the World Bank have reviewed the public health aspects concerning the use of sewage water for crop irrigation and prepared recommendations for the microbiological quality of treated wastewater used for this purpose. The limit of microorganism in sewage water used for irrigation of crop plants should not be more than 1000 fecal/100 ml of bacteria [46]. Similarly, the amount of other harmful substances in sewage water should be under minimal range. Rules and regulations in the use of sewage water vary from state to state and from country to country. In Pakistan, there is no national policy for the reuse of sewage water for crop irrigation. Furthermore, the industries do not follow the government guidelines, and

whereby sludge is depos-

http://dx.doi.org/10.5772/intechopen.75455

7

aerated through these devices which circulates at 0.25–0.35 ms−1 [41].

matter present in the effluents and thus release methane and CO<sup>2</sup>

microorganism in the wastewater gets attached with the filter media [44].

ited at the bottom, while crust is formed on the surface [42].

**3. Regulations in the use of sewage water**

water [40].

stances. These include".

ent in wastewater [43, 45].

Zayed et al. [27] tested the potential of duckweed for the removal of Cd, Cr, Cu, Ni, Pb, and Se and found that duckweed was a good accumulator of Cd, Se, and Cu. Zhu et al. [28] reported the dominant role of water hyacinth in the sewage treatment as this plant possesses a very good fibrous root system and a large biomass. They found that the water hyacinth was excellent in accumulation of organic and inorganic nutrients and trace elements including Cd, Pb, and Ag. Dos Santos and Lenzi [29] carried out experiments with aquatic *Eiochhornia crassipes* and found it useful for the removal of Pb from contaminated water. Wang et al. [30] investigated the role of five different wetland species including duckweed, sharp dock, water hyacinth, calamus, and water dropwort for their possible use in treating the polluted waters. They reported that water hyacinth and duckweed were good accumulators of Cd, water dropwort accumulated Hg, calamus was the best for the accumulation of Pb, while sharp dock was a good accumulator of N and P. Li et al. [31] conducted hydroponic experiment in order to investigate the role of three hydrophytes, that is, *Gladiolus*, *Isoetes taiwanensis and Echinodorus amazonicus* for the accumulation of Cd from contaminated water. They found that the *Gladiolus* was the best Cd accumulator as compared to other two plants. Lone et al. [32] examined the efficacy of Cu elimination from the contaminated water by *Elsholtzia argyi* and *Elsholtzia splendens* in hydroponics. The results show that *Elsholtzia argyi* showed better Cu phytofiltration than *Elsholtzia splendens*, which was associated with better ability to absorb higher Cu concentrations and translocation to shoots. Tangahu et al. [33] investigated the role of different wetland plant species for the treatment of sewage water. They found that most of the wetland species were capable for accumulation of N, P, Cd, Pb, and Hg.

Among the ferns, *Pteris vitta* has been identified as hyperaccumulator of As-contaminated soils and waters. It can accumulate up to 7500 mg of As/kg on a contaminated site without showing toxicity symptoms [34]. Trees have been recommended as a low-cost and ecologically sound solution for the remediation of heavy metals from sewage water. This ability of the trees is due to their large biomass, which can absorb large quantities of contaminants present in wastewater [35]. Plants remove contaminants from sewage water by one of the following methods:

**Phytoextraction:** Plants remove heavy metals and other pollutants from the water and soil as well as groundwater and concentrate them into their harvestable parts [36]. These plants accumulate contaminants from the water in above-ground shoot.

**Phytodegradation:** In phytodegradation process, the pollutants present in contaminated water are degraded by plants and associated microbes [37]. Plant roots in conjunction with their rhizospheric microorganisms are utilized to remediate soils irrigated with sewage water.

**Phytostabilization:** In this case, the availability and mobility of pollutants present in sewage are reduced by plants, thus reducing the risk of leaching of pollutants into groundwater [38].

**Phytovolatilization:** Plants volatilize pollutants present in sewage water. Plants extract volatile pollutants added in the soil due to irrigation with sewage water and volatilize them from the foliage [39].

**Rhizofiltration:** It is the removal of pollutants from the contaminated waters by accumulation into plant biomass. Several aquatic species including sharp dock, duckweed, and so on, have been identified and tested for the phytoremediation of heavy metals from the polluted water [40].

Besides these natural ecological treatments, other engineered approaches are also widely carried out worldwide for wastewater treatment to remove pathogen and other harmful substances. These include".

**Oxidation Ponds:** Oxidation ponds are used for reducing the biochemical oxygen demand (BOD) of wastewater. This is a very effective and simple technology, which consists of a ringshaped channel equipped with mechanical aeration devices. The wastewater is screened and aerated through these devices which circulates at 0.25–0.35 ms−1 [41].

**Anaerobic Ponds:** It is a biological treatment of wastewater in which naturally occurring bacteria are utilized for breaking the biodegradable compounds present in wastewater. These bacteria under anaerobic condition may remove high concentrations of BOD and chemical oxygen demand (COD). The presence of anaerobic bacteria in these ponds break the organic matter present in the effluents and thus release methane and CO<sup>2</sup> whereby sludge is deposited at the bottom, while crust is formed on the surface [42].

**Aerobic Ponds:** In aerobic treatment of wastewater, bacteria and algae are used that maintain aerobic condition throughout its depth. The aerobic ponds may be shallow or aerated [43].

**Trickling Filter:** This technique is used to remove or reduce pathogen and level of nitrogen in the wastewater as pathogens present in wastewater may cause serious threats to humans mostly in developing countries of the world. This trickling filter is composed of some porous material like rocks, sledge, or plastic medium having large surface area and permeability. The microorganism in the wastewater gets attached with the filter media [44].

**Activated Sludge System:** This is a biological wastewater treatment, which is mainly used for the removal of biodegradable compounds and pathogens present in wastewater. Its efficiency depends on retention time, temperature, pH, and the presence of other biological flora present in wastewater [43, 45].

#### **3. Regulations in the use of sewage water**

water velvet and duckweed for the removal of contaminants from the sewage water, is consid-

Zayed et al. [27] tested the potential of duckweed for the removal of Cd, Cr, Cu, Ni, Pb, and Se and found that duckweed was a good accumulator of Cd, Se, and Cu. Zhu et al. [28] reported the dominant role of water hyacinth in the sewage treatment as this plant possesses a very good fibrous root system and a large biomass. They found that the water hyacinth was excellent in accumulation of organic and inorganic nutrients and trace elements including Cd, Pb, and Ag. Dos Santos and Lenzi [29] carried out experiments with aquatic *Eiochhornia crassipes* and found it useful for the removal of Pb from contaminated water. Wang et al. [30] investigated the role of five different wetland species including duckweed, sharp dock, water hyacinth, calamus, and water dropwort for their possible use in treating the polluted waters. They reported that water hyacinth and duckweed were good accumulators of Cd, water dropwort accumulated Hg, calamus was the best for the accumulation of Pb, while sharp dock was a good accumulator of N and P. Li et al. [31] conducted hydroponic experiment in order to investigate the role of three hydrophytes, that is, *Gladiolus*, *Isoetes taiwanensis and Echinodorus amazonicus* for the accumulation of Cd from contaminated water. They found that the *Gladiolus* was the best Cd accumulator as compared to other two plants. Lone et al. [32] examined the efficacy of Cu elimination from the contaminated water by *Elsholtzia argyi* and *Elsholtzia splendens* in hydroponics. The results show that *Elsholtzia argyi* showed better Cu phytofiltration than *Elsholtzia splendens*, which was associated with better ability to absorb higher Cu concentrations and translocation to shoots. Tangahu et al. [33] investigated the role of different wetland plant species for the treatment of sewage water. They found that most of the wetland species were capable for

Among the ferns, *Pteris vitta* has been identified as hyperaccumulator of As-contaminated soils and waters. It can accumulate up to 7500 mg of As/kg on a contaminated site without showing toxicity symptoms [34]. Trees have been recommended as a low-cost and ecologically sound solution for the remediation of heavy metals from sewage water. This ability of the trees is due to their large biomass, which can absorb large quantities of contaminants present in wastewater [35]. Plants remove contaminants from sewage water by one of the following methods: **Phytoextraction:** Plants remove heavy metals and other pollutants from the water and soil as well as groundwater and concentrate them into their harvestable parts [36]. These plants

**Phytodegradation:** In phytodegradation process, the pollutants present in contaminated water are degraded by plants and associated microbes [37]. Plant roots in conjunction with their rhizospheric microorganisms are utilized to remediate soils irrigated with sewage water. **Phytostabilization:** In this case, the availability and mobility of pollutants present in sewage are reduced by plants, thus reducing the risk of leaching of pollutants into groundwater [38]. **Phytovolatilization:** Plants volatilize pollutants present in sewage water. Plants extract volatile pollutants added in the soil due to irrigation with sewage water and volatilize them from

ered the most effective method for the removal of heavy metals.

6 Sewage

accumulation of N, P, Cd, Pb, and Hg.

the foliage [39].

accumulate contaminants from the water in above-ground shoot.

The World Health Organization (WHO), the US Environmental Protection Agency (USEPA), and the World Bank have reviewed the public health aspects concerning the use of sewage water for crop irrigation and prepared recommendations for the microbiological quality of treated wastewater used for this purpose. The limit of microorganism in sewage water used for irrigation of crop plants should not be more than 1000 fecal/100 ml of bacteria [46]. Similarly, the amount of other harmful substances in sewage water should be under minimal range. Rules and regulations in the use of sewage water vary from state to state and from country to country. In Pakistan, there is no national policy for the reuse of sewage water for crop irrigation. Furthermore, the industries do not follow the government guidelines, and there are also no government economic incentives for these industries. In Pakistan, the sewage water is used straightaway for agricultural purpose without any purification treatment. Only Islamabad and Karachi treat a minor portion (10%) of sewage water before disposal. All the effluents are discharged in Kabul River from various industries in Khyber Pakhtunkhwa (KPK) province [47]. In Lahore, a major city of Punjab province, only three industries have wastewater treatment plants. In some regions of the country, laws and regulations have been developed for the treatment of wastewater prior to use in irrigation, but their enforcement in reality is an issue due to the absence of resources and experience.

Problems in the disposition of wastewater tend to stem from distortions due to economy-wide policies, miscarriage of directed environmental policies, and failure of institution. Inefficient water pricing worsens the problem in urban areas, where water is provided free of charge, a policy that encourages the use of wastewater for irrigation. Similarly, environmental committees have been established, but their ability to deal with specified cases is very limited due to deficiency of staff [48].

In the USA, standards are set for the reuse of wastewater in agriculture. These standards vary from state to state. In California, strictest standards have been developed for **the reuse of wastewater** [49]. California, with the lengthiest history about the regulating of reclaimed wastewater in agriculture, which only permits high-quality effluents to be used on crops. Similarly, Arizona, Florida, Hawaii, and Texas have also active water reuse programs. These states developed comprehensive, numerical water quality criteria for different water uses, including crop irrigation. Florida usually has the limits of the reuse of reclaimed water for irrigation of crop plants that are skinned and cooked before consumption [50]. **Billions of dollars are being spent on recycling of wastewater and reused in large quantities in different countries of the world (Figures 5** and **6).**

There have been no reports of contagious disease linked with agricultural reuse projects, and current criteria are considered to be acceptable in most states of the USA. Most states differentiate between produce from crops that are commercially treated or cooked before consumption, and need more strict water quality levels for produce crops. Yet, states differ in the manner in which wastewater irrigation can be implemented.

Microbiological standards for the harmless reuse of wastewater for irrigation in Latin America are varied as, for example, Brazil has no legislation. Argentina has a general reuse water law, which aimed to prevent surface water contamination which did not mention wastewater specifically [51]. Chile, introduced guidelines for the discharge of domestic and industrial effluents into rivers, lakes, and the sea; however, use of wastewater for irrigation has not been included in the legislation. Peru established roles for the reuse of wastewater after primary and secondary treatments; however, it has not established any bacterial nor nematode treatment. The Saudi Standards for effluents are strict and inadvertently enforce needless limitations on disposal and reuse of wastewater, which prevent its application for irrigation [52]. Some countries of the world have developed standards for wastewater reuse that only permit the controlled reuse of wastewater for irrigation of crop plants. Many of these are based on the WHO guidelines, including Mexico, France, Spain and Andalusia Province. Microbiological standards for wastewater reuse in agriculture have been established in Mexico over the last

20 years. In France, the Ministry of Health delivered a provisional regulation on the reuse of wastewater for irrigation. The WHO guidelines for the reuse of wastewater for agriculture and aquacultural purposes had been published in 1989, which suggest different guidelines for

**Figure 6.** Reuse of wastewater per day in different countries of the world (http://nas-sites.org/waterreuse).

**Figure 5.** Expenditures on recycling and reuse technologies used for wastewater treatments (https://recycling.

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects…

http://dx.doi.org/10.5772/intechopen.75455

9

conferenceseries.com/).

different water qualities dependent on the endpoint of discharge [53].

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects… http://dx.doi.org/10.5772/intechopen.75455 9

there are also no government economic incentives for these industries. In Pakistan, the sewage water is used straightaway for agricultural purpose without any purification treatment. Only Islamabad and Karachi treat a minor portion (10%) of sewage water before disposal. All the effluents are discharged in Kabul River from various industries in Khyber Pakhtunkhwa (KPK) province [47]. In Lahore, a major city of Punjab province, only three industries have wastewater treatment plants. In some regions of the country, laws and regulations have been developed for the treatment of wastewater prior to use in irrigation, but their enforcement in

Problems in the disposition of wastewater tend to stem from distortions due to economy-wide policies, miscarriage of directed environmental policies, and failure of institution. Inefficient water pricing worsens the problem in urban areas, where water is provided free of charge, a policy that encourages the use of wastewater for irrigation. Similarly, environmental committees have been established, but their ability to deal with specified cases is very limited due to

In the USA, standards are set for the reuse of wastewater in agriculture. These standards vary from state to state. In California, strictest standards have been developed for **the reuse of wastewater** [49]. California, with the lengthiest history about the regulating of reclaimed wastewater in agriculture, which only permits high-quality effluents to be used on crops. Similarly, Arizona, Florida, Hawaii, and Texas have also active water reuse programs. These states developed comprehensive, numerical water quality criteria for different water uses, including crop irrigation. Florida usually has the limits of the reuse of reclaimed water for irrigation of crop plants that are skinned and cooked before consumption [50]. **Billions of dollars are being spent on recycling of wastewater and reused in large quantities in differ-**

There have been no reports of contagious disease linked with agricultural reuse projects, and current criteria are considered to be acceptable in most states of the USA. Most states differentiate between produce from crops that are commercially treated or cooked before consumption, and need more strict water quality levels for produce crops. Yet, states differ in the

Microbiological standards for the harmless reuse of wastewater for irrigation in Latin America are varied as, for example, Brazil has no legislation. Argentina has a general reuse water law, which aimed to prevent surface water contamination which did not mention wastewater specifically [51]. Chile, introduced guidelines for the discharge of domestic and industrial effluents into rivers, lakes, and the sea; however, use of wastewater for irrigation has not been included in the legislation. Peru established roles for the reuse of wastewater after primary and secondary treatments; however, it has not established any bacterial nor nematode treatment. The Saudi Standards for effluents are strict and inadvertently enforce needless limitations on disposal and reuse of wastewater, which prevent its application for irrigation [52]. Some countries of the world have developed standards for wastewater reuse that only permit the controlled reuse of wastewater for irrigation of crop plants. Many of these are based on the WHO guidelines, including Mexico, France, Spain and Andalusia Province. Microbiological standards for wastewater reuse in agriculture have been established in Mexico over the last

reality is an issue due to the absence of resources and experience.

deficiency of staff [48].

8 Sewage

**ent countries of the world (Figures 5** and **6).**

manner in which wastewater irrigation can be implemented.

**Figure 5.** Expenditures on recycling and reuse technologies used for wastewater treatments (https://recycling. conferenceseries.com/).

**Figure 6.** Reuse of wastewater per day in different countries of the world (http://nas-sites.org/waterreuse).

20 years. In France, the Ministry of Health delivered a provisional regulation on the reuse of wastewater for irrigation. The WHO guidelines for the reuse of wastewater for agriculture and aquacultural purposes had been published in 1989, which suggest different guidelines for different water qualities dependent on the endpoint of discharge [53].

#### **3.1. Challenging issues**

The most challenging issue with the use of sewage water for irrigation is the infection of farmers and consumers exposed to wastewater. Besides this, the presence of organic and inorganic elements may also have human health risks. Farmers and their relatives using sewage water are exposed to health risks from parasitic worms, protozoa, viruses, and bacteria. Some farmers cannot treat some of the health problems caused by pathogenic microorganisms due to weak economic conditions. Generally, farmers irrigating with wastewater have higher rates of helminth infections and, in addition, skin and nail problems may happen to farmers using wastewater [54]. Women are most vulnerable to these infections and mostly important target group. In several countries of the world, women offer much of the labor essential to produce vegetables and perform most of the weeding and transplanting that can expose them to long periods of contact with wastewater. Women usually cook meals, making chance for transferring pathogens to the family members if good hygiene is not sustained. In West Africa, where vegetables are produced in most of the countries, women dominate the marketing process, particularly retail, of most vegetables; thus, the main target group for risk reduction measures in markets [55]. Post-harvest infection in markets can be a vital issue disturbing public health, but the implication differs, which makes it an often ignored issue in the wastewater discussion [56].

smart option for disposal because it can improve the physical properties and nutrient content in soils. However, the practice of sewage water pre-treatment is uncommon in most developing countries of the world due to which several health issues may occur. Sewage water should be treated prior to its reuse for agriculture in order to reduce the risks of harmful effects on human and animal health. One of the viable solutions for developing countries seems to be

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects…

http://dx.doi.org/10.5772/intechopen.75455

11

the use of natural ecological approaches.

The author declares no conflict of interest.

Address all correspondence to: naeemkhan@bs.qau.edu.pk

Department of Plant Sciences, Quaid-I-Azam University, Islamabad, Pakistan

Cham: Springer International Publishing; 2016. pp. 289-327

cultural Water Management. 2015;**147**:96-102

of Phytoremediation. 2016;**18**(12):1258-1269

reuse in Europe. Desalination. 2006;**187**(1-3):89-101

performance. World Health Organization; 2000

Fertility of Soils. 2000;**31**(5):414-421

Biological Sciences. 2016;**23**(1):S32-S44

[1] Valipour M, Singh VP. Global experiences on wastewater irrigation: Challenges and prospects. In: Balanced Urban Development: Options and Strategies for Liveable Cities.

[2] Rossi G. Achieving ethical responsibilities in water management: A challenge. Agri-

[3] Khan N, Bano A. Modulation of phytoremediation and plant growth by the treatment with PGPR, ag nanoparticle and untreated municipal wastewater. International Journal

[4] Friedel JK, Langer T, Siebe C, Stahr K. Effects of long-term waste water irrigation on soil organic matter, soil microbial biomass and its activities in Central Mexico. Biology and

[5] Bixio D, Thoeye C, De Koning J, Joksimovic D, Savic D, Wintgens T, Melin T. Wastewater

[6] Balkhair KS, Ashraf MA. Field accumulation risks of heavy metals in soil and vegetable crop irrigated with sewage water in western region of Saudi Arabia. Saudi Journal of

[7] World Health Organization. The world health report 2000: Health systems: Improving

**Conflict of interest**

**Author details**

Naeem Khan

**References**

Wastewater risks may be short or long term, depending on the resistance of humans and animals, while, in some cases, the impacts lies for a long period of time, especially in persons that continuously use wastewater. Beside human risks, continuous use of wastewater for irrigation results in soil salinity and sodicity. On the other hand, the presence of trace elements such as heavy metals, which are harmful for human health, can be found in sewage water effluents. The presence of microbial pollution becomes more severe with vegetables as many of them are consumed raw [57].

#### **4. Water quality improvements**

Preliminary improvements in water quality can be attained in several developing countries by at least primary treatment of sewage water, mainly where sewage water is used for irrigation. Secondary treatment can be applied at reasonable cost in some areas, using methods such as infiltration-percolation, constructed wetlands, waste-stabilization ponds and up-flow anaerobic sludge blanket reactors [58]. It is vital to aim at standards, which can be attained in the local context. WHO guidelines provide complementary alternatives for wastewater treatment and control of human exposure. Storage of reclaimed water in reservoirs develops microbiological quality and provides peak-equalization capacity, which surges the consistency of supply and increases the rate of reuse [59, 60].

#### **5. Conclusion**

Use of sewage water for irrigation not only improves the growth rate of plants but also reduces the cost of chemical fertilizers. The application of wastewater to cropland and forests is a smart option for disposal because it can improve the physical properties and nutrient content in soils. However, the practice of sewage water pre-treatment is uncommon in most developing countries of the world due to which several health issues may occur. Sewage water should be treated prior to its reuse for agriculture in order to reduce the risks of harmful effects on human and animal health. One of the viable solutions for developing countries seems to be the use of natural ecological approaches.

#### **Conflict of interest**

The author declares no conflict of interest.

#### **Author details**

Naeem Khan

**3.1. Challenging issues**

10 Sewage

of them are consumed raw [57].

**4. Water quality improvements**

supply and increases the rate of reuse [59, 60].

**5. Conclusion**

The most challenging issue with the use of sewage water for irrigation is the infection of farmers and consumers exposed to wastewater. Besides this, the presence of organic and inorganic elements may also have human health risks. Farmers and their relatives using sewage water are exposed to health risks from parasitic worms, protozoa, viruses, and bacteria. Some farmers cannot treat some of the health problems caused by pathogenic microorganisms due to weak economic conditions. Generally, farmers irrigating with wastewater have higher rates of helminth infections and, in addition, skin and nail problems may happen to farmers using wastewater [54]. Women are most vulnerable to these infections and mostly important target group. In several countries of the world, women offer much of the labor essential to produce vegetables and perform most of the weeding and transplanting that can expose them to long periods of contact with wastewater. Women usually cook meals, making chance for transferring pathogens to the family members if good hygiene is not sustained. In West Africa, where vegetables are produced in most of the countries, women dominate the marketing process, particularly retail, of most vegetables; thus, the main target group for risk reduction measures in markets [55]. Post-harvest infection in markets can be a vital issue disturbing public health, but the implication differs, which makes it an often ignored issue in the wastewater discussion [56]. Wastewater risks may be short or long term, depending on the resistance of humans and animals, while, in some cases, the impacts lies for a long period of time, especially in persons that continuously use wastewater. Beside human risks, continuous use of wastewater for irrigation results in soil salinity and sodicity. On the other hand, the presence of trace elements such as heavy metals, which are harmful for human health, can be found in sewage water effluents. The presence of microbial pollution becomes more severe with vegetables as many

Preliminary improvements in water quality can be attained in several developing countries by at least primary treatment of sewage water, mainly where sewage water is used for irrigation. Secondary treatment can be applied at reasonable cost in some areas, using methods such as infiltration-percolation, constructed wetlands, waste-stabilization ponds and up-flow anaerobic sludge blanket reactors [58]. It is vital to aim at standards, which can be attained in the local context. WHO guidelines provide complementary alternatives for wastewater treatment and control of human exposure. Storage of reclaimed water in reservoirs develops microbiological quality and provides peak-equalization capacity, which surges the consistency of

Use of sewage water for irrigation not only improves the growth rate of plants but also reduces the cost of chemical fertilizers. The application of wastewater to cropland and forests is a Address all correspondence to: naeemkhan@bs.qau.edu.pk

Department of Plant Sciences, Quaid-I-Azam University, Islamabad, Pakistan

#### **References**


[8] Barton PK, Atwater JW. Nitrous oxide emissions and the anthropogenic nitrogen in wastewater and solid waste. Journal of Environmental Engineering. 2002;**128**(2):137-150

[23] Singh J, Upadhyay SK, Pathak RK, Gupta V. Accumulation of heavy metals in soil and paddy crop (Oryza sativa), irrigated with water of Ramgarh Lake, Gorakhpur, UP, India.

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects…

http://dx.doi.org/10.5772/intechopen.75455

13

[24] Wang Y, Qiao M, Liu Y, Zhu Y. Health risk assessment of heavy metals in soils and vegetables from wastewater irrigated area, Beijing-Tianjin city cluster, China. Journal of

[25] Khan N, Bano A. Role of plant growth promoting rhizobacteria and ag-nano particle in the bioremediation of heavy metals and maize growth under municipal wastewater

[26] Carballa M, Omil F, Lema JM, Llompart M, Garcı́a-Jares C, Rodrı́guez I, Gomez M, Ternes T. Behavior of pharmaceuticals, cosmetics and hormones in a sewage treatment

[27] Zayed G, Winter J. Removal of organic pollutants and of nitrate from wastewater from the dairy industry by denitrification. Applied Microbiology and Biotechnology.

[28] Zhu YL, Zayed AM, Qian JH, De Souza M, Terry N. Phytoaccumulation of trace elements by wetland plants: II. Water hyacinth. Journal of Environmental Quality. 1999;

[29] Carvalho Dos Santos M, Lenzi E. The use of aquatic macrophytes (Eichhornia crassipes) as a biological filter in the treatment of lead contaminated effluents. Environmental

[30] Wang XL, Tao S, Dawson RW, Xu FL. Characterizing and comparing risks of polycyclic aromatic hydrocarbons in a Tianjin wastewater-irrigated area. Environmental Research.

[31] Li YH, Di Z, Ding J, Wu D, Luan Z, Zhu Y. Adsorption thermodynamic, kinetic and desorption studies of Pb 2+ on carbon nanotubes. Water Research. 2005;**39**(4):605-609

[32] Lone MI, He ZL, Stoffella PJ, Yang XE. Phytoremediation of heavy metal polluted soils and water: Progresses and perspectives. Journal of Zhejiang University Science B.

[33] Tangahu BV, Sheikh Abdullah SR, Basri H, Idris M, Anuar N, Mukhlisin M. A review on heavy metals (As, Pb, and Hg) uptake by plants through phytoremediation. International

[34] Ma H, Allen HE, Yin Y. Characterization of isolated fractions of dissolved organic matter from natural waters and a wastewater effluent. Water Research. 2001;**35**(4):985-996

[35] Mohan D, Singh KP, Ghosh D. Removal of α-picoline, β-picoline, and γ-picoline from synthetic wastewater using low cost activated carbons derived from coconut shell fibers.

irrigation. International Journal of Phytoremediation. 2016;**18**(3, 3):211-221

Toxicological & Environmental Chemistry. 2011;**93**(3):462-473

Environmental Sciences. 2012;**24**(4):690-698

plant. Water Research. 2004;**38**(12):2918-2926

Journal of Chemical Engineering. 2011;**16**:2011

Environmental Science & Technology. 2005;**39**(13):5076-5086

1998;**49**(4):469-474

2002;**90**(3):201-206

2008;**9**(3):210-220

Technology. 2000;**21**(6):615-622

**28**(1):339-344


[23] Singh J, Upadhyay SK, Pathak RK, Gupta V. Accumulation of heavy metals in soil and paddy crop (Oryza sativa), irrigated with water of Ramgarh Lake, Gorakhpur, UP, India. Toxicological & Environmental Chemistry. 2011;**93**(3):462-473

[8] Barton PK, Atwater JW. Nitrous oxide emissions and the anthropogenic nitrogen in wastewater and solid waste. Journal of Environmental Engineering. 2002;**128**(2):137-150

[9] Suval WD, Suval WD. Method and apparatus for treating varicose veins. United States

[10] Gupta VK, Ali I, Saleh TA, Nayak A, Agarwal S. Chemical treatment technologies for

[11] Asano T, Levine AD. Wastewater reclamation, recycling and reuse: Past, present, and

[12] Pearce P. Trickling filters for upgrading low technology wastewater plants for nitrogen

[13] Sharma RK, Agrawal M, Marshall F. Heavy metal contamination of soil and vegetables in suburban areas of Varanasi, India. Ecotoxicology and Environmental Safety.

[14] Das DC, Kaul RN. Greening wastelands through wastewater. Food and agriculture

[15] Raschid-Sally L, Jayakody P. Drivers and Characteristics of Wastewater Agriculture in Developing Countries: Results from a Global Assessment. Colombo: IWMI; 2009

[16] Angelakis AN, Do Monte MM, Bontoux L, Asano T.The status of wastewater reuse practice in the Mediterranean basin: Need for guidelines. Water Research. 1999;**33**(10):2201-2217

[17] Meli S, Porto M, Belligno A, Bufo SA, Mazzatura A, Scopa A. Influence of irrigation with lagooned urban wastewater on chemical and microbiological soil parameters in a citrus orchard under Mediterranean condition. Science of the Total Environment. 2002;**285**(1):69-77

[18] El-Nahhal Y, Awad Y, Safi J. Bioremediation of acetochlor in soil and water systems by

[19] Becerra-Castro C, Kidd PS, Rodríguez-Garrido B, Monterroso C, Santos-Ucha P, Prieto-Fernández Á. Phytoremediation of hexachlorocyclohexane (HCH)-contaminated soils using Cytisus striatus and bacterial inoculants in soils with distinct organic matter con-

[20] Alghobar MA, Ramachandra L, Suresha S. Effect of sewage water irrigation on soil properties and evaluation of accumulation of elements in grass crop in Mysore city, Karnataka, India. American Journal of Environmental Protection. 2014;**3**(5):283-291 [21] Safary S, Hajrasoliha S. Effects of North Isfahan sewage effluent on the soils of Borkhar region and composition of alfalfa. Paper Presented at the 5th Soil Science Congress.

[22] Rattan RK, Datta SP, Chhonkar PK, Suribabu K, Singh AK. Long-term impact of irrigation with sewage effluents on heavy metal content in soils, crops and groundwater—A

case study. Agriculture, Ecosystems & Environment. 2005;**109**(3):310-322

cyanobacterial mat. International Journal of Geosciences. 2013;**4**(5):880

tent. Environmental Pollution. 2013;**178**:202-210

Karaj: Agricultural vocational school; 1995

waste-water recycling—An overview. RSC Advances. 2012;**2**(16):6380-6388

future. Water Science and Technology. 1996;**33**(10-11):1-4

removal. Water Science and Technology. 2004;**49**(11-12):47-52

patent US 5,611,357. March 18, 1997

2007;**66**(2):258-266

12 Sewage

organization of united states


[36] Kumar PN, Dushenkov V, Motto H, Raskin I. Phytoextraction: The use of plants to remove heavy metals from soils. Environmental Science & Technology. 1995;**29**(5):1232-1238

[50] Moriarty RM, Epa WR. Palladium catalyzed cross-coupling reactions of alkenyl (phenyl) iodonium salts with organotin compounds. Tetrahedron Letters. 1992;**33**(29):4095-4098

Natural Ecological Remediation and Reuse of Sewage Water in Agriculture and Its Effects…

http://dx.doi.org/10.5772/intechopen.75455

15

[51] Peasey A, Blumenthal U, Mara D, Ruiz-Palacios G. A review of policy and standards for wastewater reuse in agriculture: A Latin American perspective. WELL study, Task; June

[52] Abu-Rizaiza OS. Modification of the standards of wastewater reuse in Saudi Arabia.

[53] World Health Organization. Health guidelines for the use of wastewater in agriculture and aquaculture: report of a WHO scientific group [meeting held in Geneva from 18 to

[54] Van der Hoek W, Hassan MU, Ensink JH, Feenstra S, Raschid-Sally L, Munir S, Aslam R, Ali N, Hussain R, Matsuno Y. Urban Wastewater: A Valuable Resource for Agriculture:

[55] Keraita B, Drechsel P, Amoah P. Influence of urban wastewater on stream water quality and agriculture in and around Kumasi, Ghana. Environment and Urbanization.

[56] Amoah P, Drechsel P, Henseler M, Abaidoo RC. Irrigated urban vegetable production in Ghana: Microbiological contamination in farms and markets and associated consumer

[57] Minhas PS, Samra JS. Wastewater Use in Peri-Urban Agriculture: Impacts and Oppor-

[58] Mara D, Horan NJ, editors. Handbook of Water and Wastewater Microbiology. London:

[59] Grabow GL, McCornick PG. Planning for water allocation and water quality using a spreadsheet-based model. Journal of Water Resources Planning and Management.

[60] Jimenez B, Asano T. Water reclamation and reuse around the world. Water Reuse: An

International Survey of Current Practice, Issues and Needs. 2008;**14**:3-26

2000. p. 68

23 November 1987]

2003;**15**(2):171-178

Academic press; 2003

2007;**133**(6):560-564

Water Research. 1999;**33**(11):2601-2608

A Case Study from Haroonabad. IWMI: Pakistan; 2002

risk groups. Journal of Water and Health. 2007;**5**(3):455-466

tunities. Karnal: Central Soil Salinity Research Institute; 2004


[50] Moriarty RM, Epa WR. Palladium catalyzed cross-coupling reactions of alkenyl (phenyl) iodonium salts with organotin compounds. Tetrahedron Letters. 1992;**33**(29):4095-4098

[36] Kumar PN, Dushenkov V, Motto H, Raskin I. Phytoextraction: The use of plants to remove heavy metals from soils. Environmental Science & Technology. 1995;**29**(5):1232-1238 [37] Burken JG, Schnoor JL.Uptake and metabolism of atrazine by poplar trees. Environmental

[38] Vangronsveld J, Van Assche F, Clijsters H. Reclamation of a bare industrial area contaminated by non-ferrous metals: In situ metal immobilization and revegetation.

[39] Burken JG, Schnoor JL. Distribution and volatilization of organic compounds following uptake by hybrid poplar trees. International Journal of Phytoremediation. 1999;**1**

[40] Vara Prasad MN, de Oliveira Freitas HM.Metal hyperaccumulation in plants: Biodiversity prospecting for phytoremediation technology. Electronic Journal of Biotechnology.

[41] Von Sperling M. Carlos Augustos de Lemos Chernicharo. Biological wastewater treatment

[42] Okoh AI, Odjadjare EE, Igbinosa EO, Osode AN. Wastewater treatment plants as a source of microbial pathogens in receiving watersheds. African Journal of Biotechnology.

[43] Elimelech M. The global challenge for adequate and safe water. Journal of Water Supply:

[44] Kornaros M, Lyberatosa G. Biological treatment of wastewaters from a dye manufacturing company using a trickling filter. Journal of Hazardous Materials. 2006;**136**(1):95-102

[45] Doorn MRJ, Towprayoon S, Maria S, Vieira M, Irving W, Palmer C, Pipatti R, Wang C. Wastewater treatment and discharge. In 2006 IPCC Guidelines for National Green-

[46] Shuval HI, Wax Y, Yekutiel P, Fattal B. Transmission of enteric disease associated with wastewater irrigation: A prospective epidemiological study. American Journal of Public

[47] Tariq M, Ali M, Shah Z. Characteristics of industrial effluents and their possible impacts

[48] Murtaza G, Zia MH. Wastewater production, treatment and use in Pakistan. In: Second Regional Workshop of the Project Safe Use of Wastewater in Agriculture; May 2012.

[49] Blumenthal UJ, Mara DD, Peasey A, Ruiz-Palacios G, Stott R. Guidelines for the microbiological quality of treated wastewater used in agriculture: Recommendations for revising WHO guidelines. Bulletin of the World Health Organization. 2000;**78**(9):1104-1116

house Gas Inventories volume 5. (Waste); WMO, UNEP. 2006. pp. 6: 1-6, 28

on quality of underground water. Soil and Environment. 2006;**25**(1):64-69

Science & Technology. 1997;**31**(5):1399-1406

Environmental Pollution. 1995;**87**(1, 1):51-59

in warm climate regions. IWA publishing. 2017

Research and Technology - AQUA. 2006;**55**:3-10

(2):139-151

14 Sewage

2003;**6**(3):285-321

2007;**6**(25):2932-2944

Health. 1989;**79**(7):850-852

pp. 16-18


**Chapter 2**

**Provisional chapter**

**Treatment of Sewage (Domestic Wastewater or**

**Treatment of Sewage (Domestic Wastewater or** 

**Integrating Constructed Wetland with Microbial** 

Maitreyie Narayan, Praveen Solanki and

Maitreyie Narayan, Praveen Solanki and

http://dx.doi.org/10.5772/intechopen.75658

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Rajeev Kumar Srivastava

Rajeev Kumar Srivastava

**Abstract**

treatment, bioenergy

**Cell**

**Fuel Cell**

**Municipal Wastewater) and Electricity Production by**

**Municipal Wastewater) and Electricity Production by** 

DOI: 10.5772/intechopen.75658

**Integrating Constructed Wetland with Microbial Fuel**

Proper treatment of wastewater is important to human health and societal development, and the commonly applied wastewater treatment technologies based on aerobic treatment have a significant demand for energy. Thus, new treatment technologies with low energy consumption and possible recovery of valuable resources (e.g., energy and water) from wastewater become of strong interest. Among the newly developed concepts, microbial fuel cells (MFCs) integrated with constructed wetland appear to be very attractive because of direct electricity generation from organic compounds and treatment of wastewater. Constructed wetland coupled with microbial fuel cell (CW-MFC) is an emerging technology in recent years and has attracted a lot of attention from researchers in the fields of wastewater treatment and bioenergy production. CW-MFC is a promising technology in the fields of wastewater treatment and bioenergy. However, at current power levels, the advantage of combining the two is mainly because of the enhancement of wastewater treatment in anaerobic zones within the wetland. New operational strate-

**Keywords:** microbial fuel cell, constructed wetland, electricity production, wastewater

gies need to be explored to increase and utilize electricity output.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

#### **Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity Production by Integrating Constructed Wetland with Microbial Fuel Cell Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity Production by Integrating Constructed Wetland with Microbial Fuel Cell**

DOI: 10.5772/intechopen.75658

Maitreyie Narayan, Praveen Solanki and Rajeev Kumar Srivastava Maitreyie Narayan, Praveen Solanki and Rajeev Kumar Srivastava

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.75658

#### **Abstract**

Proper treatment of wastewater is important to human health and societal development, and the commonly applied wastewater treatment technologies based on aerobic treatment have a significant demand for energy. Thus, new treatment technologies with low energy consumption and possible recovery of valuable resources (e.g., energy and water) from wastewater become of strong interest. Among the newly developed concepts, microbial fuel cells (MFCs) integrated with constructed wetland appear to be very attractive because of direct electricity generation from organic compounds and treatment of wastewater. Constructed wetland coupled with microbial fuel cell (CW-MFC) is an emerging technology in recent years and has attracted a lot of attention from researchers in the fields of wastewater treatment and bioenergy production. CW-MFC is a promising technology in the fields of wastewater treatment and bioenergy. However, at current power levels, the advantage of combining the two is mainly because of the enhancement of wastewater treatment in anaerobic zones within the wetland. New operational strategies need to be explored to increase and utilize electricity output.

**Keywords:** microbial fuel cell, constructed wetland, electricity production, wastewater treatment, bioenergy

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

## **1. Introduction**

#### **1.1. Water**

Water is derived from the Anglo-Saxon and Low German word, *wæter* which is an odorless, flavorless, and colorless substance that is necessary to all living beings that we all are aware of. It is the main constituent of earth's streams, lakes, oceans, and the fluids of most living organisms [1]. Its chemical formula is H<sup>2</sup> O, which means that each of its molecules contains one atom oxygen and two atoms hydrogen that are connected by a bond known as "covalent bond". Water is found in three different forms on earth, that is, solid, liquid, and gas [2]. These forms of water depend on the temperature. Water on our planet is present as a **solid form** in the ice-caped areas at the North and South Poles, **liquid** in rivers, streams, and oceans and is **gas** or vapor form in the atmosphere [3].

under various river action plans (from 1978 to 1979 onward) and are located in (just 5% of)

Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity…

http://dx.doi.org/10.5772/intechopen.75658

19

Energy use can account for as much as 10% of a local government's annual operating budget [13]. A considerable amount of this municipal energy use occurs at water and wastewater treatment services. With pumps, motors, and other equipment operating 24 h a day, 7 days a week, water and wastewater services can be among the largest consumers of energy in a community and thus among the largest contributors to the community's total GHG emissions. Nationally, the energy used by water and wastewater utilities accounts for 35% of typical U.S. municipal energy budgets [14]. Electricity use accounts for 25–40% of the operating budgets for wastewater utilities and approximately 80% of drinking water processing and distribution costs [14]. Drinking water and wastewater systems account for approximately 3–4% of energy use in the United States, resulting in the emissions of more than 45 million tons of GHGs

There is a growing demand for new energy sources due to the limited accessibility and pollution caused by the use of fossil fuels. At present, the annual energy demand is approximately 13 terawatts (TW) worldwide and it is estimated to reach around 23 TW by the year 2050 [16]. Bioelectrochemical systems (BESs) have considerably boomed over the past decade for their contribution as an emerging sustainable technology for concurrent electricity production and wastewater treatment [17]. Microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are two examples of a speedily developing biotechnology, generally known as bioelectrochemical systems (BES), that combine biological and electrochemical processes to generate electricity, hydrogen, or other useful chemicals. Moreover, BESs are also identified as efficient bioreactors for the treatment of recalcitrant pollutants and toxic wastewaters; the process is

termed as bioelectrochemical treatment (BET) or microbial electroremediation [18].

Microbial fuel cell (MFC) technology is the symbol of the newest approach for generating electricity from biomass using microorganisms. While the first observation of electrical current generated by bacteria is generally credited to Potter in 1911 [19], very few practical advances were achieved in this field even 55 years later [20]. In the early 1990s, fuel cells became of more interest and work on MFCs began to increase [21]. A microbial fuel cell is a tool that converts chemical energy to electrical energy with the help of the catalytic reaction of bacteria [21–26]. A microbial fuel cell consists of anode and cathode sections, which are separated by a specific membrane. Microbes are present in the anode section and they oxidize fuel (electron donor)

cities/towns along the banks of major rivers [12].

**2. Introduction of bioelectrochemical systems**

**1.4. Energy cost of wastewater treatment**

annually [15].

**2.1. Biochemical system**

**2.2. Microbial fuel cell**

But the present scenario says that all the water resources that are present in the globe are under a major stress. Today, however, expansion of industries, agriculture, damming, urbanization, population, and pollution threaten these unique resources in many parts of the earth [4].

But the main concern now is providing safe drinking water to the more than 1 billion people who currently lack it; this is one of the utmost public health challenges facing governments today. In many developing countries, safe water, free of pathogens and other contaminants, is unavailable to much of the population, and water contamination remains a concern even for developed countries too with good water supplies and advanced treatment systems [5].

#### **1.2. Distribution of water**

The first living organisms undoubtedly arose in an aqueous environment and during the course of evolution it has been shaped by the properties of the aqueous medium in which life began [6]. Therefore, life on the earth that is originated from sea and water plays a pioneer role for evolutionary development of species, life forms, and relatively complex molecules [7]. It is an abundant essential resource on earth and covers 71% of the earth's surface. This earth's water consists of 3% freshwater of total water supply and is found as either surface water or groundwater, however, 97% as saltwater [8]. Therefore [9] has concluded that the human interference, inadequate supply, and inappropriate management are the major causes [10] leading to scarcity of resources that impedes sustainable development [11].

#### **1.3. Wastewater**

Wastewater or sewage is the byproduct of water. There are the household uses such as bathing, dishwashing, laundry, and, of course, flushing the toilet. Additionally, industries use water for many purposes including processing and cleaning or rinsing of parts. With rapid growth of cities, urbanization, and industrialization the quantity of gray/wastewater is increasing in the same proportion. As per Central Public Health and Environmental Engineering Organization (CPHEEO) estimates about 70–80% of total water supplied for domestic use gets generated as wastewater. Typically, 200–500 L of wastewater are generated for every person. In India, there are 234 Sewage Water Treatment plants (STPs). Most of these were developed under various river action plans (from 1978 to 1979 onward) and are located in (just 5% of) cities/towns along the banks of major rivers [12].

#### **1.4. Energy cost of wastewater treatment**

**1. Introduction**

organisms [1]. Its chemical formula is H<sup>2</sup>

**gas** or vapor form in the atmosphere [3].

**1.2. Distribution of water**

**1.3. Wastewater**

Water is derived from the Anglo-Saxon and Low German word, *wæter* which is an odorless, flavorless, and colorless substance that is necessary to all living beings that we all are aware of. It is the main constituent of earth's streams, lakes, oceans, and the fluids of most living

one atom oxygen and two atoms hydrogen that are connected by a bond known as "covalent bond". Water is found in three different forms on earth, that is, solid, liquid, and gas [2]. These forms of water depend on the temperature. Water on our planet is present as a **solid form** in the ice-caped areas at the North and South Poles, **liquid** in rivers, streams, and oceans and is

But the present scenario says that all the water resources that are present in the globe are under a major stress. Today, however, expansion of industries, agriculture, damming, urbanization, population, and pollution threaten these unique resources in many parts of the earth [4].

But the main concern now is providing safe drinking water to the more than 1 billion people who currently lack it; this is one of the utmost public health challenges facing governments today. In many developing countries, safe water, free of pathogens and other contaminants, is unavailable to much of the population, and water contamination remains a concern even for developed countries too with good water supplies and advanced treatment systems [5].

The first living organisms undoubtedly arose in an aqueous environment and during the course of evolution it has been shaped by the properties of the aqueous medium in which life began [6]. Therefore, life on the earth that is originated from sea and water plays a pioneer role for evolutionary development of species, life forms, and relatively complex molecules [7]. It is an abundant essential resource on earth and covers 71% of the earth's surface. This earth's water consists of 3% freshwater of total water supply and is found as either surface water or groundwater, however, 97% as saltwater [8]. Therefore [9] has concluded that the human interference, inadequate supply, and inappropriate management are the major causes [10]

Wastewater or sewage is the byproduct of water. There are the household uses such as bathing, dishwashing, laundry, and, of course, flushing the toilet. Additionally, industries use water for many purposes including processing and cleaning or rinsing of parts. With rapid growth of cities, urbanization, and industrialization the quantity of gray/wastewater is increasing in the same proportion. As per Central Public Health and Environmental Engineering Organization (CPHEEO) estimates about 70–80% of total water supplied for domestic use gets generated as wastewater. Typically, 200–500 L of wastewater are generated for every person. In India, there are 234 Sewage Water Treatment plants (STPs). Most of these were developed

leading to scarcity of resources that impedes sustainable development [11].

O, which means that each of its molecules contains

**1.1. Water**

18 Sewage

Energy use can account for as much as 10% of a local government's annual operating budget [13]. A considerable amount of this municipal energy use occurs at water and wastewater treatment services. With pumps, motors, and other equipment operating 24 h a day, 7 days a week, water and wastewater services can be among the largest consumers of energy in a community and thus among the largest contributors to the community's total GHG emissions. Nationally, the energy used by water and wastewater utilities accounts for 35% of typical U.S. municipal energy budgets [14]. Electricity use accounts for 25–40% of the operating budgets for wastewater utilities and approximately 80% of drinking water processing and distribution costs [14]. Drinking water and wastewater systems account for approximately 3–4% of energy use in the United States, resulting in the emissions of more than 45 million tons of GHGs annually [15].

#### **2. Introduction of bioelectrochemical systems**

#### **2.1. Biochemical system**

There is a growing demand for new energy sources due to the limited accessibility and pollution caused by the use of fossil fuels. At present, the annual energy demand is approximately 13 terawatts (TW) worldwide and it is estimated to reach around 23 TW by the year 2050 [16]. Bioelectrochemical systems (BESs) have considerably boomed over the past decade for their contribution as an emerging sustainable technology for concurrent electricity production and wastewater treatment [17]. Microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are two examples of a speedily developing biotechnology, generally known as bioelectrochemical systems (BES), that combine biological and electrochemical processes to generate electricity, hydrogen, or other useful chemicals. Moreover, BESs are also identified as efficient bioreactors for the treatment of recalcitrant pollutants and toxic wastewaters; the process is termed as bioelectrochemical treatment (BET) or microbial electroremediation [18].

#### **2.2. Microbial fuel cell**

Microbial fuel cell (MFC) technology is the symbol of the newest approach for generating electricity from biomass using microorganisms. While the first observation of electrical current generated by bacteria is generally credited to Potter in 1911 [19], very few practical advances were achieved in this field even 55 years later [20]. In the early 1990s, fuel cells became of more interest and work on MFCs began to increase [21]. A microbial fuel cell is a tool that converts chemical energy to electrical energy with the help of the catalytic reaction of bacteria [21–26].

A microbial fuel cell consists of anode and cathode sections, which are separated by a specific membrane. Microbes are present in the anode section and they oxidize fuel (electron donor) which finally generates electrons and protons. Electrons are transferred to the cathode area through the circuit and the protons through the specific membrane. Electrons and protons are consumed in the cathode compartment reducing oxygen to water.

**2.4. Substrates used in microbial fuel cells**

pounds such as sulfate [44].

**3. Constructed wetland**

face water flow), and direction of flow.

**3.1. Surface flow (free water surface)**

adsorb or precipitate phosphorus (P) [47] (**Figure 1**).

"artificial" [45].

In generating electricity in MFCs, substrate is regarded as one of the most important biological factors [34]. A huge variety of substrates can be used in MFCs for power generation. The substrates not only influence the MFC performance including the power density (PD) and Coulombic efficiency (CE) but also the integral composition of the microorganism's community in the anode [35]. During the development of this technology, low molecular weight substrates were employed, that is, carbohydrates such as glucose, fructose, xylose, sucrose, maltose, and trehalose [36–38], organic acids such as acetate, propionate, butyrate, lactate, succinate, and malate [39–42], alcohols such as ethanol and methanol [43], and inorganic com-

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21

Constructed wetlands (CW) systems are entirely man-made wetlands for wastewater treatment, which relate various technological designs, using natural wetland processes, associated with wetland hydrology, soils, microorganisms, and plants. Thus, CWs are engineered systems that have been designed and constructed to utilize the natural processes involving wetland vegetation, soils, and their associated microbial assemblages to assist in treating wastewater. Synonymous terms to "constructed" include "man-made," "engineered," or

Constructed wetlands (CWs) have been used to treat wastewater ranging from domestic to industrial and from urban to agricultural along with treating stormwater runoff, leachates and mine drainage, and for sludge dewatering through a combination of physical, chemical, and biological processes. Constructed wetlands (CW) are a feasible alternative option for removing nutrients and other contaminants from wastewater and have been used to treat many different types of wastewater for decades. CW mimics the properties of a natural wetland, and filtration occurs as a result of physical, chemical, and biological processes that are similar to those that take place in a natural wetland. There are numerous types of CW, and they can be differentiated based on dominant vegetation type, hydrology (surface vs. subsur-

A surface flow CW is comprised of a sealed packed basin or series of basins filled with 20–30 cm of gravel and with a water depth of 20–40 cm. Planted macrophytes emerge over the surface of the water but roots are in the soil. Effluent water is treated as it flows over the soil/ substrate. These systems effectively remove organic material through microbial degradation and settling and inorganic materials through settling alone [46]. They are efficient at removing nitrogen (N) through denitrification and ammonia volatilization but are unable to effectively remove phosphorus (P) as water does not tend to come in contact with soil particles which

#### **2.3. Design of MFCs**

A suitable design is foremost an important characteristic feature in MFCs and researchers have come up with several designs of MFCs over the past few years with better performance [27].

#### *2.3.1. Single chamber microbial fuel cells*

Single compartment MFC offers simpler design and cost savings. It typically consists of an anode chamber with a microfiltration membrane air-cathode. The cathode was exposed to air on one side and water on the other side (inside). There is no proton exchange membrane. The microfiltration membrane is applied directly onto the water-facing side of the cathode.

#### *2.3.2. Dual chamber microbial fuel cells*

Dual chamber MFC consists of an anaerobic anode chamber and an aerobic cathode chamber which are usually separated by a proton exchange membrane (PEM). Substrate is oxidized by bacteria generating electrons and protons at the anode chamber. The protons traveling through the PEM and the electrons traveling through the external circuit are combined with electron acceptors at the cathode chamber. The anode is inoculated with a mixed solution of anaerobic sludge and substrate like glucose. On the other hand, cathode is inoculated with aerobic sludge.

#### *2.3.3. Air-chamber microbial fuel cells*

Dual-chamber MFCs are mainly used in laboratory range and cannot be adapted for continuous treatment of organic matter due to the demand of oxygenated water. In a substitute design without aqueous cathode, cathodic electrode is bonded straight to proton exchange membrane so that air can be openly reduced [28–32]. The earliest air-cathode MFC architecture was designed and reported that an oxygen gas diffusion electrode could be used as a cathode in bioelectrochemical fuel cell [33]. But this air-cathode design has not drawn much attention in MFC research until Liu reported the air-cathode MFC could produce much greater power than typical aqueous-cathode ones.

The architecture of air-cathode MFCs is aimed to optimize some characteristics of two-chamber MFCs, such as low relative power output, high cost of cathode catalysts and membranes, and energy requirement for intensive air/oxygen sparging. Another advantage of the air-cathode over the two-chamber is the reduction of the high internal resistance of MFCs, which is a key factor to enhance electricity production.

#### **2.4. Substrates used in microbial fuel cells**

which finally generates electrons and protons. Electrons are transferred to the cathode area through the circuit and the protons through the specific membrane. Electrons and protons are

A suitable design is foremost an important characteristic feature in MFCs and researchers have come up with several designs of MFCs over the past few years with better performance [27].

Single compartment MFC offers simpler design and cost savings. It typically consists of an anode chamber with a microfiltration membrane air-cathode. The cathode was exposed to air on one side and water on the other side (inside). There is no proton exchange membrane. The microfiltration membrane is applied directly onto the water-facing side of the

Dual chamber MFC consists of an anaerobic anode chamber and an aerobic cathode chamber which are usually separated by a proton exchange membrane (PEM). Substrate is oxidized by bacteria generating electrons and protons at the anode chamber. The protons traveling through the PEM and the electrons traveling through the external circuit are combined with electron acceptors at the cathode chamber. The anode is inoculated with a mixed solution of anaerobic sludge and substrate like glucose. On the other hand, cathode is inoculated with

Dual-chamber MFCs are mainly used in laboratory range and cannot be adapted for continuous treatment of organic matter due to the demand of oxygenated water. In a substitute design without aqueous cathode, cathodic electrode is bonded straight to proton exchange membrane so that air can be openly reduced [28–32]. The earliest air-cathode MFC architecture was designed and reported that an oxygen gas diffusion electrode could be used as a cathode in bioelectrochemical fuel cell [33]. But this air-cathode design has not drawn much attention in MFC research until Liu reported the air-cathode MFC could produce much greater power

The architecture of air-cathode MFCs is aimed to optimize some characteristics of two-chamber MFCs, such as low relative power output, high cost of cathode catalysts and membranes, and energy requirement for intensive air/oxygen sparging. Another advantage of the air-cathode over the two-chamber is the reduction of the high internal resistance of MFCs, which is a

consumed in the cathode compartment reducing oxygen to water.

**2.3. Design of MFCs**

20 Sewage

cathode.

aerobic sludge.

*2.3.1. Single chamber microbial fuel cells*

*2.3.2. Dual chamber microbial fuel cells*

*2.3.3. Air-chamber microbial fuel cells*

than typical aqueous-cathode ones.

key factor to enhance electricity production.

In generating electricity in MFCs, substrate is regarded as one of the most important biological factors [34]. A huge variety of substrates can be used in MFCs for power generation. The substrates not only influence the MFC performance including the power density (PD) and Coulombic efficiency (CE) but also the integral composition of the microorganism's community in the anode [35]. During the development of this technology, low molecular weight substrates were employed, that is, carbohydrates such as glucose, fructose, xylose, sucrose, maltose, and trehalose [36–38], organic acids such as acetate, propionate, butyrate, lactate, succinate, and malate [39–42], alcohols such as ethanol and methanol [43], and inorganic compounds such as sulfate [44].

## **3. Constructed wetland**

Constructed wetlands (CW) systems are entirely man-made wetlands for wastewater treatment, which relate various technological designs, using natural wetland processes, associated with wetland hydrology, soils, microorganisms, and plants. Thus, CWs are engineered systems that have been designed and constructed to utilize the natural processes involving wetland vegetation, soils, and their associated microbial assemblages to assist in treating wastewater. Synonymous terms to "constructed" include "man-made," "engineered," or "artificial" [45].

Constructed wetlands (CWs) have been used to treat wastewater ranging from domestic to industrial and from urban to agricultural along with treating stormwater runoff, leachates and mine drainage, and for sludge dewatering through a combination of physical, chemical, and biological processes. Constructed wetlands (CW) are a feasible alternative option for removing nutrients and other contaminants from wastewater and have been used to treat many different types of wastewater for decades. CW mimics the properties of a natural wetland, and filtration occurs as a result of physical, chemical, and biological processes that are similar to those that take place in a natural wetland. There are numerous types of CW, and they can be differentiated based on dominant vegetation type, hydrology (surface vs. subsurface water flow), and direction of flow.

#### **3.1. Surface flow (free water surface)**

A surface flow CW is comprised of a sealed packed basin or series of basins filled with 20–30 cm of gravel and with a water depth of 20–40 cm. Planted macrophytes emerge over the surface of the water but roots are in the soil. Effluent water is treated as it flows over the soil/ substrate. These systems effectively remove organic material through microbial degradation and settling and inorganic materials through settling alone [46]. They are efficient at removing nitrogen (N) through denitrification and ammonia volatilization but are unable to effectively remove phosphorus (P) as water does not tend to come in contact with soil particles which adsorb or precipitate phosphorus (P) [47] (**Figure 1**).

**Figure 1.** Diagram of a surface flow constructed wetland. Image by Dr. Sarah white [48].

#### **3.2. Subsurface flow**

Subsurface flow wetlands are made up of an impervious basin filled with a layer of gravel of size 10–20 mm [46]. Wetland plants are grown in the gravel layer and water flows through the gravel layer, around the plant roots. Subsurface flow systems are differentiated based on whether the main direction of flow is horizontal or vertical [48]. In a horizontal flow (HF) system, water enters through an inlet, flows slowly through the substrate, and exits through an outlet on the other side of the system. HF systems effectively remove organic material and suspended solids through anaerobic microbial and sedimentation, respectively. Nitrogen is removed mainly via denitrification, as ammonia volatilization may not take place due to lack of oxygen. Generally, because of the lack of ammonia volatilization occurring, total N removal by these systems is low [45] (**Figure 2**).

#### **3.3. Hybrid constructed wetlands**

Various types of CWs can be combined to achieve higher removal efficiency. The design consists of two stages, several parallel vertical flow (VF) beds followed by several horizontal flow (HF) beds in series (VSSF-HSSF system). The VSSF wetland is intended to remove organics and suspended solids and to promote nitrification, while in HSSF wetland denitrification and further removal of organics and suspended solids occur. Another configuration is a HSSF-VSSF system. A large HSSF bed is placed first to remove organics and suspended solids and to promote denitrification. An intermittently loaded small VF bed is used for additional removal of organics and suspended solids and for nitrification of ammonia into nitrate. To maximize removal of total N, however, the nitrified effluent from the VF bed must be recycled to a sedimentation tank [49] (**Figure 3**).

**4. Microbial fuel cell implemented in constructed wetland: Recently** 

**Figure 2.** Diagram of a subsurface flow constructed wetland. Image by Dr. Sarah white [48].

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23

A microbial fuel cell coupled constructed wetland (CW-MFC) system is a latest mechanism that embeds the MFC into the constructed wetland (CW) to treat the wastewater and produce electricity. Research suggested that wetland plants promote the cathode performance of MFCs [51]. Technology combining CW systems with microbial fuel cells (CW-MFC) has

**emerged technology**

**Figure 3.** Diagram of a hybrid constructed wetland [50].

Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity… http://dx.doi.org/10.5772/intechopen.75658 23

**Figure 2.** Diagram of a subsurface flow constructed wetland. Image by Dr. Sarah white [48].

**Figure 3.** Diagram of a hybrid constructed wetland [50].

**3.2. Subsurface flow**

22 Sewage

removal by these systems is low [45] (**Figure 2**).

**3.3. Hybrid constructed wetlands**

mentation tank [49] (**Figure 3**).

Subsurface flow wetlands are made up of an impervious basin filled with a layer of gravel of size 10–20 mm [46]. Wetland plants are grown in the gravel layer and water flows through the gravel layer, around the plant roots. Subsurface flow systems are differentiated based on whether the main direction of flow is horizontal or vertical [48]. In a horizontal flow (HF) system, water enters through an inlet, flows slowly through the substrate, and exits through an outlet on the other side of the system. HF systems effectively remove organic material and suspended solids through anaerobic microbial and sedimentation, respectively. Nitrogen is removed mainly via denitrification, as ammonia volatilization may not take place due to lack of oxygen. Generally, because of the lack of ammonia volatilization occurring, total N

**Figure 1.** Diagram of a surface flow constructed wetland. Image by Dr. Sarah white [48].

Various types of CWs can be combined to achieve higher removal efficiency. The design consists of two stages, several parallel vertical flow (VF) beds followed by several horizontal flow (HF) beds in series (VSSF-HSSF system). The VSSF wetland is intended to remove organics and suspended solids and to promote nitrification, while in HSSF wetland denitrification and further removal of organics and suspended solids occur. Another configuration is a HSSF-VSSF system. A large HSSF bed is placed first to remove organics and suspended solids and to promote denitrification. An intermittently loaded small VF bed is used for additional removal of organics and suspended solids and for nitrification of ammonia into nitrate. To maximize removal of total N, however, the nitrified effluent from the VF bed must be recycled to a sedi-

#### **4. Microbial fuel cell implemented in constructed wetland: Recently emerged technology**

A microbial fuel cell coupled constructed wetland (CW-MFC) system is a latest mechanism that embeds the MFC into the constructed wetland (CW) to treat the wastewater and produce electricity. Research suggested that wetland plants promote the cathode performance of MFCs [51]. Technology combining CW systems with microbial fuel cells (CW-MFC) has promise for both wastewater treatment and bio-electric production [52–54]. In this system approach, electricity is produced with biodegradable substances as bacteria oxidize organic or inorganic matter in wetland soils [54].

and 21.33 mW/m<sup>2</sup>

(49.68 ± 2.83 mA/m<sup>2</sup>

**Type Liquid** 

Horizontal subsurface flow **volume (L)**

Vertical flow 5.4 Anode-graphite

Vertical upflow 3.7 Anode-graphite

Vertical flow 12.4 Anode-granular

Vertical flow 12.4 Anode-granular

Vertical flow — Anode-granular

Vertical upflow 8.1 Anode-granular

Vertical upflow — Anode-carbon felt

**Table 1.** Reported performance of CW-MFCs.

plate

plate

plates

plates

96 Anode-graphite plates

plates

Cathode-graphite

Cathode-graphite

activated carbon Cathode-granular activated carbon

Cathode-graphite

activated carbon Cathode-granular activated carbon

activated carbon Cathode-granular activated carbon

Cathode-granular graphite

Cathode-carbon felt

graphite

, respectively, compared with 44.63 mW/m<sup>2</sup>

rial growth and providing more reaction sites for the reduction of O2

of 250 mg/L. Current densities were increased when the SSM was embedded in carbon cloth

carbon cloth and GAC increased the surface area of the electrode thereby facilitating bacte-

the wastewater will affect the ability of electrogenic bacteria to produce power. **Table 1** has shown the performance of CW-MFC by using different electrode materials and also of organic loads. Operating under batch mode, [55] noted that as dye concentration increased from 1000 to 1500 mg/L the average power density more than halved due to the toxic effect of the dye.

**Electrode material Initial COD** 

) and granular activated charcoal (GAC) (63.69 ± 1.78 mA/m<sup>2</sup>

Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity…

**(mg/L) and (% removal)**

for influent COD concentrations

http://dx.doi.org/10.5772/intechopen.75658

**Max. power References**

1500 (74.9) 15.7 mW/m<sup>2</sup> [55]

1058 (76.5) 9.4 mW/m<sup>2</sup> [56]

180 (86) 0.302 W/m<sup>3</sup> [57]

250 (80–100) 0.15 mW/m<sup>2</sup> [51]

193–205 (94.8) 12.42 mW/m<sup>2</sup> [58]

300 (72.5) 0.852 W/m<sup>3</sup> [68]

411–854 (64) 0.268 W/m<sup>3</sup> [53]

314.8 (100) 6.12 mW/m<sup>2</sup> [54]

). Both the

25

. Other compounds in

#### **4.1. Architecture and operation of constructed wetland coupled with microbial fuel cells**

In order to maximize the redox gradient (as it is an essential factor in producing an electrical current in MFCs), most CW-MFCs have been operated under upflow conditions with a buried anode and a cathode at the surface and/or in the plant rhizosphere. This arrangement minimizes the dissolved oxygen (DO) at the anode while ensuring maximum availability in the cathode region. Initially a glass wool separator was used by [55, 56] to provide a 'sharp' redox profile. However, the use of a separator where an upflow regime is being used with a buried anode and a cathode at the surface may not be necessary as this arrangement provides a sufficient redox profile for MFC integration [57–59]. Unfortunately, utilizing the natural redox gradient afforded by an upflow regime results in large electrode separation and contributes greatly to the ohmic resistance of the system [60–64]. Carbon and graphite are commonly used as electrode materials in MFC studies since they offer long-term sustainability owing to their high electrical conductivity, non-oxidative nature, and the fact that they offer a good medium for the attachment and growth of microbial communities.

#### **4.2. Performance of constructed wetland coupled with microbial fuel cells**

#### *4.2.1. Functioning as constructed wetland regarding wastewater treatment*

MFC integrated into CW is a possible and economical way to achieve the objectives of both wastewater treatment and electricity generation. The ability of CWs to treat wastewater is well established [65, 66] and, as such, integrating MFCs into CWs should not come at the price of reducing their effectiveness at removing contaminants from wastewater. Preliminary investigations indicated that CW-MFCs perform similarly to previous CW studies by removing 75% [55] and 76.5% [56] of COD. The inclusion of the MFC component has shown the ability to improve the COD removal efficiency in CWs. The inclusion of plant roots at the cathode of CW-MFCs slightly improves COD removal efficiencies in the wetland compared with non-planted and rhizosphere-anode CW-MFCs [58, 57]. The presence of the anode improved COD removal efficiencies by 12.65%. Thirty-three percent of COD was removed at the anode occupying 13.6% of the liquid volume in a CW-MFC operated by [53].

#### *4.2.2. Functioning as MFC regarding electricity production*

MFC converts the biodegradable compounds to generate electricity by utilizing bacteria. COD loading greatly affects the performance of CW-MFCs. A balance is necessary between providing sufficient organics for oxidation at the anode and limiting the amount of COD arriving at the cathode. In a vertical upflow CW-MFC designed by [67], an increasing trend in power densities was observed as influent COD was increased from 50 to 250 mg/L. However, further increases in concentration to 500 and 1000 mg/L resulted in average power densities of 33.7 and 21.33 mW/m<sup>2</sup> , respectively, compared with 44.63 mW/m<sup>2</sup> for influent COD concentrations of 250 mg/L. Current densities were increased when the SSM was embedded in carbon cloth (49.68 ± 2.83 mA/m<sup>2</sup> ) and granular activated charcoal (GAC) (63.69 ± 1.78 mA/m<sup>2</sup> ). Both the carbon cloth and GAC increased the surface area of the electrode thereby facilitating bacterial growth and providing more reaction sites for the reduction of O2 . Other compounds in the wastewater will affect the ability of electrogenic bacteria to produce power. **Table 1** has shown the performance of CW-MFC by using different electrode materials and also of organic loads. Operating under batch mode, [55] noted that as dye concentration increased from 1000 to 1500 mg/L the average power density more than halved due to the toxic effect of the dye.


**Table 1.** Reported performance of CW-MFCs.

promise for both wastewater treatment and bio-electric production [52–54]. In this system approach, electricity is produced with biodegradable substances as bacteria oxidize organic

In order to maximize the redox gradient (as it is an essential factor in producing an electrical current in MFCs), most CW-MFCs have been operated under upflow conditions with a buried anode and a cathode at the surface and/or in the plant rhizosphere. This arrangement minimizes the dissolved oxygen (DO) at the anode while ensuring maximum availability in the cathode region. Initially a glass wool separator was used by [55, 56] to provide a 'sharp' redox profile. However, the use of a separator where an upflow regime is being used with a buried anode and a cathode at the surface may not be necessary as this arrangement provides a sufficient redox profile for MFC integration [57–59]. Unfortunately, utilizing the natural redox gradient afforded by an upflow regime results in large electrode separation and contributes greatly to the ohmic resistance of the system [60–64]. Carbon and graphite are commonly used as electrode materials in MFC studies since they offer long-term sustainability owing to their high electrical conductivity, non-oxidative nature, and the fact that they offer a good

MFC integrated into CW is a possible and economical way to achieve the objectives of both wastewater treatment and electricity generation. The ability of CWs to treat wastewater is well established [65, 66] and, as such, integrating MFCs into CWs should not come at the price of reducing their effectiveness at removing contaminants from wastewater. Preliminary investigations indicated that CW-MFCs perform similarly to previous CW studies by removing 75% [55] and 76.5% [56] of COD. The inclusion of the MFC component has shown the ability to improve the COD removal efficiency in CWs. The inclusion of plant roots at the cathode of CW-MFCs slightly improves COD removal efficiencies in the wetland compared with non-planted and rhizosphere-anode CW-MFCs [58, 57]. The presence of the anode improved COD removal efficiencies by 12.65%. Thirty-three percent of COD was removed at the anode occupying 13.6% of the liquid volume in a CW-MFC

MFC converts the biodegradable compounds to generate electricity by utilizing bacteria. COD loading greatly affects the performance of CW-MFCs. A balance is necessary between providing sufficient organics for oxidation at the anode and limiting the amount of COD arriving at the cathode. In a vertical upflow CW-MFC designed by [67], an increasing trend in power densities was observed as influent COD was increased from 50 to 250 mg/L. However, further increases in concentration to 500 and 1000 mg/L resulted in average power densities of 33.7

**4.1. Architecture and operation of constructed wetland coupled with microbial fuel** 

medium for the attachment and growth of microbial communities.

*4.2.1. Functioning as constructed wetland regarding wastewater treatment*

*4.2.2. Functioning as MFC regarding electricity production*

**4.2. Performance of constructed wetland coupled with microbial fuel cells**

or inorganic matter in wetland soils [54].

**cells**

24 Sewage

operated by [53].

Similarly, [68] reported that as the proportion of ABRX3 dye (measured as COD) increased incrementally from 10 to 90% the maximum power density, obtained from the power density curves, fell from 0.455 to 0.138 W/m<sup>3</sup> . The reduction in electrical performance was primarily attributed to anodic polarization.

The CW-MFCs tested in this study were suitable for long-term stable operation and showed strong adaptability to different water qualities. HRT significantly influenced the decolorization process in the anode layer. The power density, the Coulombic efficiency, the open circuit voltage, the decolorization rate, and the COD removal rate increased initially and then decreased with the elongation of the HRT.

## **5. Comparison of CW-MFC with traditional biological treatment processes**

Biological treatment is an important and integral part of any wastewater treatment plant that treats wastewater from either municipality or industry having soluble organic impurities or a mix of the two types of wastewater sources. The obvious economic advantage, both in terms of capital investment and operating costs, of biological treatment over other treatment processes like chemical oxidation, thermal oxidation, and so on, has cemented its place in any integrated wastewater treatment plant. Conventional activated sludge process (ASP) system is the most common and oldest bio-treatment process used to treat municipal and industrial wastewater, but the main problem with this is that it requires aeration, which uses a large amount of electrical energy. But on the other hand, MFC-centered hybrid technologies have attracted attention during the last few years due to their compatibility and dual advantages of energy recovery and wastewater treatment. In this system, oxygen is needed for the aerobic chamber but oxygen enters into that chamber through rhizosphere zone and no energy is required for this purpose but in fact electricity is harnessed during the system operation. **Table 2** lists the comparison of CW-MFC and conventional activated sludge process and highlights the benefits of CW-MFC which not only treating the wastewater but also we are harnessing electricity out of it.

If we talk about land requirement for the biological treatment system, lots of land are needed for different purposes like *Trickling filter, Rotating biological filter*, *Facultative (waste stabilization) ponds, Aerated lagoons, Activated sludge process, Anaerobic ponds, Septic tanks, Imhoff tanks,* and so on.

Microbial reactions take place, along with it

Wastewater with low to medium organic impurities

http://dx.doi.org/10.5772/intechopen.75658

27

chemicals are also required

Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity…

followed by aerobic treatment)

Wastewater treatment using conventional system like activated sludge technology is still energy and cost consuming, and chemicals have to be used in the treatment process. Constructed wetlands in combination with bioelectrochemical technology can provide an alternative. Wastewater treatment through CW-MFC is possible using a small-scale, constructed wetland-microbial fuel cell system. Good results were obtained with regard to organics removal, filtration of suspended solids, nutrient removal, and passive disinfection.

The CW-MFC is a promising technology in the fields of wastewater treatment and bioenergy. However, at current power levels, the biggest advantage of combining the two may come from the enhancement of wastewater treatment in anaerobic zones within the wetland. For the electrical output to be increased new operational strategies need to be explored to reduce the electrode spacing while maintaining the required redox conditions in the system. If the existing limitations of the combined system can be addressed, this prototype CW-MFC system can provide a real alternative for wastewater treatment, when built on a larger scale. Since the operational costs of a constructed wetland are very low, and given the MFC can produce electricity at a relatively low cost, this system could be competitive to existing water treatment plants.

MFCs implemented in CWs may increase not only CW treatment capacity but also would be of use as a biosensor tool to monitor treatment performance and operational conditions (such

**6. Conclusions and future perspectives**

**Parameters CW-MFC Biological treatment**

Process principle Microbial reactions take place, no

Applications Wastewater with medium to high

chemicals required

organic impurities

Production of electricity Yes No

**Table 2.** Differences between CW-MFC and biological treatment system.

Reaction kinetic Moderate Relatively low

Capital investment Relatively low Relatively high

Energy No energy required Energy required for aeration

Land Large piece of land not required Large piece of land is required

Net sludge yield No sludge formation Relatively high (e.g., aerobic treatment) Post-treatment No post-treatment Required (for anaerobic treatment, invariably

Biological treatment system uses two processes, that is, aerobic and anaerobic. Aerobic, as the name suggests, means that the reactions takes place in the presence of air (oxygen) while anaerobic means in the absence of air (oxygen). These two terms are directly related to the type of bacteria or microorganisms that are involved in the degradation of impurities in a given wastewater and the operating conditions of the bioreactor. Therefore, aerobic treatment utilizes those microorganisms that use molecular/free oxygen to assimilate organic impurities, that is, convert them into carbon dioxide, water, and biomass. The anaerobic treatment processes, on the other hand, take place in the absence of air (and thus molecular/free oxygen) by those microorganisms (also called anaerobes) which do not require air (molecular/ free oxygen) to assimilate organic impurities. As this process takes place in the absence of air, it is relatively slow compared to aerobic, because to create an anaerobic environment is a very difficult task.


**Table 2.** Differences between CW-MFC and biological treatment system.

Similarly, [68] reported that as the proportion of ABRX3 dye (measured as COD) increased incrementally from 10 to 90% the maximum power density, obtained from the power density

The CW-MFCs tested in this study were suitable for long-term stable operation and showed strong adaptability to different water qualities. HRT significantly influenced the decolorization process in the anode layer. The power density, the Coulombic efficiency, the open circuit voltage, the decolorization rate, and the COD removal rate increased initially and then

Biological treatment is an important and integral part of any wastewater treatment plant that treats wastewater from either municipality or industry having soluble organic impurities or a mix of the two types of wastewater sources. The obvious economic advantage, both in terms of capital investment and operating costs, of biological treatment over other treatment processes like chemical oxidation, thermal oxidation, and so on, has cemented its place in any integrated wastewater treatment plant. Conventional activated sludge process (ASP) system is the most common and oldest bio-treatment process used to treat municipal and industrial wastewater, but the main problem with this is that it requires aeration, which uses a large amount of electrical energy. But on the other hand, MFC-centered hybrid technologies have attracted attention during the last few years due to their compatibility and dual advantages of energy recovery and wastewater treatment. In this system, oxygen is needed for the aerobic chamber but oxygen enters into that chamber through rhizosphere zone and no energy is required for this purpose but in fact electricity is harnessed during the system operation. **Table 2** lists the comparison of CW-MFC and conventional activated sludge process and highlights the benefits of CW-MFC which not only treating the wastewater but also we are har-

Biological treatment system uses two processes, that is, aerobic and anaerobic. Aerobic, as the name suggests, means that the reactions takes place in the presence of air (oxygen) while anaerobic means in the absence of air (oxygen). These two terms are directly related to the type of bacteria or microorganisms that are involved in the degradation of impurities in a given wastewater and the operating conditions of the bioreactor. Therefore, aerobic treatment utilizes those microorganisms that use molecular/free oxygen to assimilate organic impurities, that is, convert them into carbon dioxide, water, and biomass. The anaerobic treatment processes, on the other hand, take place in the absence of air (and thus molecular/free oxygen) by those microorganisms (also called anaerobes) which do not require air (molecular/ free oxygen) to assimilate organic impurities. As this process takes place in the absence of air, it is relatively slow compared to aerobic, because to create an anaerobic environment is a very

**5. Comparison of CW-MFC with traditional biological treatment** 

. The reduction in electrical performance was primarily

curves, fell from 0.455 to 0.138 W/m<sup>3</sup>

decreased with the elongation of the HRT.

attributed to anodic polarization.

**processes**

26 Sewage

nessing electricity out of it.

difficult task.

If we talk about land requirement for the biological treatment system, lots of land are needed for different purposes like *Trickling filter, Rotating biological filter*, *Facultative (waste stabilization) ponds, Aerated lagoons, Activated sludge process, Anaerobic ponds, Septic tanks, Imhoff tanks,* and so on.

#### **6. Conclusions and future perspectives**

Wastewater treatment using conventional system like activated sludge technology is still energy and cost consuming, and chemicals have to be used in the treatment process. Constructed wetlands in combination with bioelectrochemical technology can provide an alternative. Wastewater treatment through CW-MFC is possible using a small-scale, constructed wetland-microbial fuel cell system. Good results were obtained with regard to organics removal, filtration of suspended solids, nutrient removal, and passive disinfection.

The CW-MFC is a promising technology in the fields of wastewater treatment and bioenergy. However, at current power levels, the biggest advantage of combining the two may come from the enhancement of wastewater treatment in anaerobic zones within the wetland. For the electrical output to be increased new operational strategies need to be explored to reduce the electrode spacing while maintaining the required redox conditions in the system. If the existing limitations of the combined system can be addressed, this prototype CW-MFC system can provide a real alternative for wastewater treatment, when built on a larger scale. Since the operational costs of a constructed wetland are very low, and given the MFC can produce electricity at a relatively low cost, this system could be competitive to existing water treatment plants.

MFCs implemented in CWs may increase not only CW treatment capacity but also would be of use as a biosensor tool to monitor treatment performance and operational conditions (such as influent organic matter concentration). Organic matter concentration is currently determined by means of analysis of the biochemical oxygen demand (BOD) after 5 days (BOD<sup>5</sup> ) or the chemical oxygen demand (COD). Despite the fact that these methods are universally used, BOD<sup>5</sup> has a limitation in terms of being time consuming, and is not suitable for online process monitoring.

[9] Chhimwal M, Narayan M, Srivastava RK.Electricity generation from microbial fuel cell by using different bio-wastes as substrate. Environment and Ecology. 2017;**35**(4A):2958-2964

Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity…

http://dx.doi.org/10.5772/intechopen.75658

29

[10] Ingole NA, Ram RN, Ranjan R, Shankhwar AK. Advance application of geospatial technology for fisheries perspective in *Tarai* region of Himalayan state of Uttarakhand. Sustainable Water Resources Management. 2015;**2**:181-187. DOI: 10.1007/s40899-015-

[11] Shankhwar AK, Srivastava RK. Biomass production through grey water fertigation in *Eucalyptus hybrid* and its economic significance. Environmental Progress & Sustainable

[12] CPCB. Parivesh Sewage Pollution—News Letter. Parivesh Bhawan, East Arjun Nagar, Delhi: Central Pollution Control Board, Ministry of Environment and Forests. Govt. of India; 2005. Available: http://cpcbenvis.nic.in/newsletter/sewagepollution/contentsewagepoll-0205.htm

[13] U.S. DOE. State Energy Program: Projects by Topic—What Are State and Local Government Facility Projects in the States? 2005. Available: http://www1.eere.energy.

[14] NYSERDA. Statewide Assessment of Energy Use by the Municipal Water and Wastewater Sector. New York State Energy Research and Development Authority. 2008. Available: http://www.nyserda.ny.gov/~/media/Files/EERP/Commercial/Sector/ Municipal%20Water%20and%20Wastewater%20Facilities/nys-assess\energyuse.

[15] U.S. EPA. State and Local Climate and Energy Program: Water/Wastewater. 2012. Available: http://www.epa.gov/statelocalclimate/local/topics/water.html [Accessed: 12

[16] Chae KJ, Choi MJ, Kim KY, Ajayi FF, Chang IS, Kim IS. A solarpowered microbial electrolysis cell with a platinum catalyst-free cathode to produce hydrogen. Environmental

[17] Mohan SV, Mohanakrishna G, Velvizhi G, Babu VL, Sarma PN. Bio-catalyzed electrochemical treatment of real field dairy wastewater with simultaneous power generation.

[18] Mohanakrishna G, Mohan SV, Sarma PN. Bio-electrochemical treatment of distillery wastewater in microbial fuel cell facilitating decolorization and desalination along with

[19] Potter MC. Electrical effects accompanying the decomposition of organic compounds. Proceedings of the Royal Society of London. Series B, Biological Sciences. 1911;**84**:260-276

[20] Lewis K. Symposium on bioelectrochemistry of microorganisms: 1V. Biochemical fuel

[21] Allen RM, Bennetto HP. Microbial fuel cells: Electricity production from carbohydrates.

Science & Technology. 2009;**43**:9525-9530. DOI: 10.1021/es9022317

power generation. Journal of Hazardous Materials. 2010;**177**(1):487-494

0012-9. ISSN: 2363-5037

Energy. 2015;**34**(1):222-226

October, 12

gov/wip/sep.html [Accessed 22 May, 11]

ashx?sc\_database=web [Accessed 9 May, 11]

Biochemical Engineering Journal. 2010;**51**(1):32-39

cells. Bacteriological Reviews. 1966;**30**(1):101-113

Applied Biochemistry and Biotechnology. 1993;**39**(2):27-40

COD is a faster procedure for assessing organic matter concentration in wastewater, yet it is quite costly and produces toxic reagents that might pose a threat to the environment. Overall, the synergy between CWs and MFCs has been so far mostly based on optimization for energy production. Besides the interest that an energy surplus can have in the context of CW technology, further research shall be focused on the optimization of both technologies to fully address other benefits of MFC implementation in CWs such as treatment efficiency improvement, process monitoring, and the reduction of clogging, or methane emissions.

#### **Author details**

Maitreyie Narayan\*, Praveen Solanki and Rajeev Kumar Srivastava

\*Address all correspondence to: maitreyie25apr@gmail.com

Department of Environmental Sciences, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India

#### **References**


[9] Chhimwal M, Narayan M, Srivastava RK.Electricity generation from microbial fuel cell by using different bio-wastes as substrate. Environment and Ecology. 2017;**35**(4A):2958-2964

as influent organic matter concentration). Organic matter concentration is currently determined by means of analysis of the biochemical oxygen demand (BOD) after 5 days (BOD<sup>5</sup>

or the chemical oxygen demand (COD). Despite the fact that these methods are universally

COD is a faster procedure for assessing organic matter concentration in wastewater, yet it is quite costly and produces toxic reagents that might pose a threat to the environment. Overall, the synergy between CWs and MFCs has been so far mostly based on optimization for energy production. Besides the interest that an energy surplus can have in the context of CW technology, further research shall be focused on the optimization of both technologies to fully address other benefits of MFC implementation in CWs such as treatment efficiency improve-

ment, process monitoring, and the reduction of clogging, or methane emissions.

Department of Environmental Sciences, G. B. Pant University of Agriculture and

[4] http://efc.syr.edu/wp-content/uploads/2015/03/Chapter1-web.pdf [Internet] [5] http://ga.water.usgs.gov/edu/watercycleevapotranspiration.html [Internet]

[6] Nelson DL, Cox MM. Lehninger Principles of Biochemistry. 4th ed. Vol. 1119. New York:

[7] Shankhwar AK, Nautiyal N, Kumar B, Rastogi A, Srivastava RK, Singh V. Potential impacts of climate change on freshwater resources: A critical review. In: Singh V, Kumar B, Nautiyal N, Rastogi A, Shankhwar AK, editors. Climate Change and Hydrosphere: The Water Planet in Crises. New Delhi: Biotech Books; 2012. pp. 121-146.

[8] De AK. Environmental Chemistry. 7th ed. New Delhi, India: New Age International (P)

Maitreyie Narayan\*, Praveen Solanki and Rajeev Kumar Srivastava

[1] http://www.deltawerken.com/What-is-water/341.html [Internet] [2] http://articles.extension.org/pages/60575/what-is-water [Internet]

\*Address all correspondence to: maitreyie25apr@gmail.com

Technology, Pantnagar, Uttarakhand, India

[3] https://en.wikipedia.org/wiki/Water [Internet]

WH Freeman and Company; 2007

ISBN: 9788176222570

Ltd; 2010. 366 p

has a limitation in terms of being time consuming, and is not suitable for online

used, BOD<sup>5</sup>

28 Sewage

process monitoring.

**Author details**

**References**

)


[22] Kim BH, Ikeda T, Park HS, Kim HJ, Hyun MS, Kano K, Takagi K, Tatsumi H.Electrochemical activity of an Fe(III)-reducing bacterium, Shewanella putrefaciens IR-1, in the presence of alternative electron acceptors. Biotechnology Techniques. 1999;**13**:475-478

[36] Chaudhuri SK, Lovley DR. Electricity generation by direct oxidation of glucose in medi-

Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity…

http://dx.doi.org/10.5772/intechopen.75658

31

[37] Kim N, Choi Y, Jung S, Kim S. Development of microbial fuel cells using *Proteus vulgaris*.

[38] Kim N, Choi Y, Jung S, Kim S. Effect of initial carbon sources on the performance of microbial fuel cells containing *Proteus vulgaris*. Biotechnology and Bioengineering.

[39] Bond DR, Lovley DR. Evidence for involvement of an electron shuttle in electricity generation by *Geothrix fermentans*. Applied and Environmental Microbiology.

[40] Holmes DE, Bond DR, Lovley DR. Electron transfer by *Desulfobulbus propionicus*to Fe(III) and graphite electrodes. Applied and Environmental Microbiology. 2004;**70**(2):1234 [41] Holmes DE, Bond DR, O'Neil RA, Reimers CE, Tender LR, Lovley DR. Microbial communities associated with electrodes harvesting electricity from a variety of aquatic sedi-

[42] Min B, Logan BE. Continuous electricity generation from domestic wastewater and organic substrates in a flat plate microbial fuel cell. Environmental Science & Technology.

[43] Kim JR, Jung SH, Regan JM, Logan B. Electricity generation and microbial community analysis of alcohol powered microbial fuel cells. Bioresource Technology. 2007;**98**:

[44] Rabaey K, Van de Somperl K, Magnien L, Boon N, Aelterman P, Caluwaert P, De Schamphelaire L, Pham H, Vermeulen J, Verhaege M, Lens P, Verstraete W.Microbial fuel cells for sulfide removal. Environmental Science & Technology. 2006;**40**(17):5218-5224

[45] Vymazal J. Removal of nutrients in various types of constructed wetlands. Science of the

[47] Taylor MD, White SA, Chandler SL, Klaine SJ, Whitwell T. Nutrient management of nursery runoff water using constructed wetland systems. HortTechnology.

[48] Oki LR, White SA. Ecological approaches used in nurseries to treat water. 2012. http://ucanr.org/sites/UCNFAnews/Feature\_Stories/Ecological\_approaches\_used\_

[49] Vymazal J. Constructed wetlands for wastewater treatment: Five decades of experience.

[50] Dong Jin Lee, Se Won Kang, Jong Hwan Park, Seong Heon Kim, Ik Won Choi, Tae Hee Hwang, Byung Jin Lim, Soo Jung Jung, Ha Na Park, Ju Sik Cho, Dong Cheol Seo.

[46] Vymazal J. Constructed wetlands for wastewater treatment. Water. 2010;**2**:530-549

atorless-microbial fuel cells. Nature Biotechnology. 2003;**21**(10):1229-1232

Bulletin of the Korean Chemical Society. 2000;**21**(1):44-48

2000;**70**(1):109-114

2005;**71**(4):2186-2189

2004;**38**(21):5809-5814

2568-2577

2006;**16**:610-614

ments. Microbial Ecology. 2004;**48**:178-190

Total Environment. 2007;**380**:48-65

in\_nurseries\_to\_treat \_water/

Environmental Science & Technology. 2011;**45**(1):65-69


[36] Chaudhuri SK, Lovley DR. Electricity generation by direct oxidation of glucose in mediatorless-microbial fuel cells. Nature Biotechnology. 2003;**21**(10):1229-1232

[22] Kim BH, Ikeda T, Park HS, Kim HJ, Hyun MS, Kano K, Takagi K, Tatsumi H.Electrochemical activity of an Fe(III)-reducing bacterium, Shewanella putrefaciens IR-1, in the presence

[23] Stirling JL, Bennetto HP, Delaney GM, Mason JR, Roller SB, Tanaka K, Thurston CF.Microbial

[24] Rawson DM, Willmer AJ. Whole-cell biosensors for environmental monitroing.

[25] Suzuki S, Karube I, Matsunaga T. Application of a biochemical fuel cell to wastewater.

[26] Wingard LB, Shaw CH, Castner JF. Bioelectrochemical fuel cells. Enzyme and Microbial

[27] Du Z, Li H, Gu T. A state of the art review on microbial fuel cells: A promising technology for wastewater treatment and bioenergy. Biotechnology Advances. 2007;**25**:464-482

[28] Lee HS, Parameswaran P, Kato-Marcus A, Torres CI, Rittman BE. Evaluation of energyconversion efficiencies in microbial fuel cells (MFCs) utilizing fermentable and non-fer-

[29] Li F, Sharma Y, Lei Y, Li B, Zhou Q. Microbial fuel cells: The effects of configurations, electrolyte solutions and electrode materials on power generation. Applied Biochemistry

[30] Liu H, Logan BE. Electricity generation using an air-cathode single chamber microbial fuel cell in the presence and absence of a proton exchange membrane. Environmental

[31] Liu H, Ramnarayanan R, Logan BE. Production of electricity during wastewater treatment using a single chamber microbial fuel cell. Environmental Science & Technology.

[32] Liu H, Cheng S, Logan BE. Production of electricity from acetate or butyrate using a single-chamber microbial fuel cell. Environmental Science & Technology.

[33] Liu H, Cheng S, Logan BE. Power generation in fed-batch microbial fuel cells as a function of ionic strength, temperature and reactor configuration. Environmental Science &

[34] Liu Z, Liu J, Zhang S, Su Z. Study of operational performance and electrical response on mediator-less microbial fuel cells fed with carbon- and protein-rich substrates.

[35] Chae KJ, Choi MJ, Lee JW, Kim KY, Kim IS. Effect of different substrates on the performance, bacterial diversity, and bacterial viability in microbial fuel cells. Bioresource

of alternative electron acceptors. Biotechnology Techniques. 1999;**13**:475-478

fuel cells. Biochemical Society Transactions. 1983;**11**(4):451-453

Biotechnology and Bioengineering Symposium. 1978;**8**:501-511

mentable substrates. Water Research. 2008;**10**:1501-1510

Biosensors & Bioelectronics. 1989;**4**:299-311

Technology. 1982;**4**:137-142

30 Sewage

and Biotechnology. 2010;**160**:168-181

Science & Technology. 2004;**38**:4040-4046

2004;**38**:2281-2285

2005;**39**:658-662

Technology. 2005;**39**:5488-5493

Technology. 2009;**100**:3518-3525

Biochemical Engineering Journal. 2009;**45**:185-191


Enhancement of nutrient removal in a hybrid constructed wetland utilizing an electric fan air blower with renewable energy of solar and wind power. Journal of Chemistry. 2015;1-8. https://www.researchgate.net/publication/282437504\_Enhancement\_ of\_Nutrient\_Removal\_in\_a\_Hybrid\_Constructed\_Wetland\_Utilizing\_an\_Electric\_ Fan\_Air\_Blower\_with\_Renewable\_Energy\_of\_Solar\_and\_Wind\_Power [Accessed: 28 December, 2017]

[63] Ahn Y, Logan BE. A multi-electrode continuous flow microbial fuel cell with separator electrode assembly design. Applied Microbiology and Biotechnology. 2012;**93**:2241-2248

Treatment of Sewage (Domestic Wastewater or Municipal Wastewater) and Electricity…

http://dx.doi.org/10.5772/intechopen.75658

33

[64] Srikanth S, Venkata Mohan S. Influence of terminal electron acceptor availability to the anodic oxidation on the electrogenic activity of microbial fuel cell (MFC). Bioresource

[65] Harrington R, O'Donovan G, McGrath G. Integrated constructed wetlands (ICW) working at the landscape scale: The Ann valley project, Ireland. Ecological Informatics.

[66] Vymazal J. Constructed wetlands for treatment of industrial wastewaters: A review.

[67] Liu S, Song H, Wei S, Yang F, Li X. Bio-cathode materials evaluation and configuration optimization for power output of vertical subsurface flow constructed wetland micro-

[68] Fang Z, Song H, Cang N, Li X. Electricity production from azo dye wastewater using a microbial fuel cell coupled constructed wetland operating under different operating

bial fuel cell systems. Bioresource Technology. 2014;**166**:575-583

conditions. Biosensors & Bioelectronics. 2015;**68**:135-141

Technology. 2012;**123**:480-487

Ecological Engineering. 2014;**73**:724-751

2013;**14**:104-107


[63] Ahn Y, Logan BE. A multi-electrode continuous flow microbial fuel cell with separator electrode assembly design. Applied Microbiology and Biotechnology. 2012;**93**:2241-2248

Enhancement of nutrient removal in a hybrid constructed wetland utilizing an electric fan air blower with renewable energy of solar and wind power. Journal of Chemistry. 2015;1-8. https://www.researchgate.net/publication/282437504\_Enhancement\_ of\_Nutrient\_Removal\_in\_a\_Hybrid\_Constructed\_Wetland\_Utilizing\_an\_Electric\_ Fan\_Air\_Blower\_with\_Renewable\_Energy\_of\_Solar\_and\_Wind\_Power [Accessed: 28

[51] Villaseňor J, Capilla P, Rodrigo MA, Caňizares P, Femάndez FJ. Water Research.

[52] Corbella C, Guivernau M, Viñas M, Puigagut J. Operational, design and microbial aspects related to power production with microbial fuel cells implemented in constructed wet-

[53] Doherty L, Zhao Y, Zhao X, Hu Y, Hao X, Xu L, Liu R. A review of arecently emerged technology: Constructed wetland-microbial fuel cells. Water Research. 2015;**85**:38-45 [54] Oon YL, Ong SA, Ho LN, Wong YS, Oon YS, Lehl HK, Thung WE. Hybrid system up-flow constructed wetland integrated with microbialfuel cell for simultaneous wastewater treat-

[55] Yadav AK, Dash P, Mohanty A, Abbassi R, Mishra BK. Performance assessment of innovative constructed wetland-microbial fuel cell for electricity production and dye

[56] Zhao Y, Collum S, Phelan M, Goodbody T, Doherty L, Hu Y. Preliminary investigation of constructed wetland incorporating microbial fuel cell: Batch and continuous flow trials.

[57] Fang Z, Song H, Cang N, Li X. Performance of microbial fuel cell coupled constructed wetland system for decolorization of azo dye and bioelectricity generation. Bioresource

[58] Liu S, Song H, Li X, Yang F. Power generation enhancement by utilizing plant photosynthate in microbial fuel cell coupled constructed wetland system. International Journal of

[59] Corbella C, Garfi M, Puigagut J. Vertical redox profiles in treatment wetlands as function of hydraulic regime and macrophytes presence: Surveying the optimal scenario for microbial fuel cell implementation. Science of the Total Environment. 2014;**470-471**:754-758 [60] Cheng S, Liu H, Logan BE. Increased power generation in a continuous flow MFC with advective flow through the porous anode and reduced electrode spacing. Environmental

[61] Liu H, Cheng S, Huang L, Logan B. Scale-up of membrane-free single chamber microbial

[62] Fan Y, Han SK, Liu H. Improved performance of CEA microbial fuel cell with increased

Photoenergy. 2013;**2013**:10. Article ID: 172010. DOI: 10.1155/2013/172010

ment and electricity generation. Bioresource Technology. 2015;**186**:270-275

December, 2017]

32 Sewage

2013;**47**:6731-6738

lands. Water Research. 2015;**84**:232-242

removal. Ecological Engineering. 2012;**47**:126-131

Chemical Engineering Journal. 2013;**229**:364-370

Technology. 2013;**144**:165-171

Science & Technology. 2006;**40**:2426-2432

fuel cells. Journal of Power Sources. 2008;**179**:274-279

reactor size. Energy & Environmental Science. 2012;**5**:8273-8280


**Chapter 3**

**Provisional chapter**

**The Importance of Media in Wastewater Treatment**

The chapter reviews the importance of media in wastewater treatment. The chapter discusses the application of natural fillings (i.e. quartz sand, zeolite and clay) and plastic materials fillings (i.e. PET flakes) for domestic sewage treatment. The effectiveness of

*coli* and coliform bacteria) by using secondary and tertiary filters have been presented. The effectiveness of one-layer filters and multi-layer filters during the filtration of wastewater pre-treated in a septic tank has been discussed. The possibility of statistical tools (e.g. ANOVA and principal component analysis) to evaluate the filters performance has been described. The phenomena affected the removal of ammonium and phosphates ions from domestic sewage in a vertical flow filter filled with a calcined limestone-silicate rock

3− ions) and indicator bacteria (*Escherichia* 

+ and PO<sup>4</sup>

**Keywords:** vertical flow filter, ammonium and phosphate ions, indicator bacteria

Safe water and proper sanitation are crucial for human health and quality of our environment. According to a WHO/UNICEF monitoring program, in 2015 still around 660 million people did not have access to proper quality sources of drinking water. Estimated number of

Leaky septic tanks, introducing pre-treated sewage directly into the ground by drainage or discharging untreated sewage directly into watercourses contaminate groundwater and surface water. Eutrophication of water bodies is a serious problem but their contamination with

people lacking access to an appropriate sanitary system is 2.4 billion [1, 2].

**The Importance of Media in Wastewater Treatment**

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.75625

Ewa Dacewicz and Krzysztof Chmielowski

Ewa Dacewicz and Krzysztof Chmielowski

http://dx.doi.org/10.5772/intechopen.75625

removing biogenic compounds (NH<sup>4</sup>

**Abstract**

were also presented.

pathogens is even more dangerous.

**1. Introduction**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

#### **The Importance of Media in Wastewater Treatment The Importance of Media in Wastewater Treatment**

DOI: 10.5772/intechopen.75625

Ewa Dacewicz and Krzysztof Chmielowski Ewa Dacewicz and Krzysztof Chmielowski

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.75625

#### **Abstract**

The chapter reviews the importance of media in wastewater treatment. The chapter discusses the application of natural fillings (i.e. quartz sand, zeolite and clay) and plastic materials fillings (i.e. PET flakes) for domestic sewage treatment. The effectiveness of removing biogenic compounds (NH<sup>4</sup> + and PO<sup>4</sup> 3− ions) and indicator bacteria (*Escherichia coli* and coliform bacteria) by using secondary and tertiary filters have been presented. The effectiveness of one-layer filters and multi-layer filters during the filtration of wastewater pre-treated in a septic tank has been discussed. The possibility of statistical tools (e.g. ANOVA and principal component analysis) to evaluate the filters performance has been described. The phenomena affected the removal of ammonium and phosphates ions from domestic sewage in a vertical flow filter filled with a calcined limestone-silicate rock were also presented.

**Keywords:** vertical flow filter, ammonium and phosphate ions, indicator bacteria

#### **1. Introduction**

Safe water and proper sanitation are crucial for human health and quality of our environment. According to a WHO/UNICEF monitoring program, in 2015 still around 660 million people did not have access to proper quality sources of drinking water. Estimated number of people lacking access to an appropriate sanitary system is 2.4 billion [1, 2].

Leaky septic tanks, introducing pre-treated sewage directly into the ground by drainage or discharging untreated sewage directly into watercourses contaminate groundwater and surface water. Eutrophication of water bodies is a serious problem but their contamination with pathogens is even more dangerous.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

There are a number of pathogenic microorganisms transferred through water. They include rotaviruses and polioviruses, pathogenic bacteria or parasitic Protozoa (*Cryptosporidium sp.* oocysts and *Giardia sp.* cysts) [3, 4], as well as *an opportunistic pathogen Pseudomonas aeruginosa* [5–7]. The presence of pathogenic coliform bacteria (*Citrobacter sp., Enterobacter sp., Escherichia coli, Klebsiella sp.* and *Proteus sp.*) in aquatic environment indicates fresh contamination with urine and feces.

organic and inorganic substances. The biofilm may grow and reach from a few to a few dozen centimeters inside the bed [10, 11]. Quality of the treated sewage discharged from biosand filters (BSF) depends on sand grain size, filtration rate and intensity of biochemical processes

Heterotrophic bacteria that develop in an aerated sand bed are responsible for removing biodegradable organic substances as determined by BOD. As per literature reports, sand bed filtration of pre-treated wastewater allows for a removal of 92% of organic carbon [22] and a reduction of BOD by over 98% [14, 23–25]. An experiment by Wąsik et al. [25] showed that in a system septic tank/vertical filter with no additional aeration, filled with washed sand with equivalent grain diameter d10 = 0.62 mm, the removal of organic substances from domestic sewage was the most intense when the filter layers were 15 and 30 cm thick. Apart from heterotrophic bacteria, the sand filters in the presence of ammonium nitrogen are also colonized by nitrifying bacteria responsible for oxidation of ammonium nitrogen to nitrate nitrogen. White [22] reported 91% nitrification of sewage treated with sand filtering of secondary clarifier effluent. Chmielowski [14] demonstrated nitrification effectiveness for treatment of septic tank effluent to reach 92%. Chmielowski and Ślizowski claimed [12, 13] that equivalent diameter of sand bed grain exceeding 1.65 mm lowered sewage treatment effectiveness. Additionally, denitrification may occur in non-aerated zones of the filter. According to literature, the effectiveness of nitrate nitrogen removal in sand filters may be as high as 98% [23]. Properly designed vertical flow sand filters in the system with septic tank also provide a significant reduction of pathogenic bacteria count. In a field study on a technical scale,

and on average 10 CFU of *Salmonella sp*. and *Shigella sp.* **Table 1** lists the effectiveness of patho-

Langenbach et al. [10, 11] confirmed usability of a vertical flow sand filter in the removal of feces bacteria from secondary clarifier effluents over 59–148 days of the filter operation. They managed to reduced *Escherichia coli* count by ca. 2 log10 units, while medium count of the

Sand, 1.05 mm WWTP effluent 95.32–98.02% Aloo et al. 2014 [27]

Lab model SSF, secondary effluent

**log10**

2.4 log units fecal coliforms

2.2–3.5 log units *Escherichia coli*

1.6–2.2 log units *Escherichia coli*

1.1–4.7 log units *Escherichia coli*

genic bacteria removal from wastewater on sand filters in various studies [26–30].

–1 × 10<sup>4</sup> CFU of *Escherichia coli*

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625 37

. Such a good performance of

Yettefti et al. 2013 [26]

Kauppinen et al. 2014 [28]

Pfannes et al. 2015 [29]

Seeger et al. 2016 [30]

**References**

Chmielowski [14] received treated sewage containing 1 × 102

bacteria in the filtrate was not higher than 1 × 102 CFU/100 cm<sup>3</sup>

Sand, 0–8 mm Raw municipal post-screen

wastewater

of WWTP

Sand, d10 = 0.21 mm Lab model SSF, secondary effluent of WWTP

**Type of material, grain size Scale of work, medium Removal efficiency,** 

Effluent from an anoxic denitryfying reactor treating domestic wastewater

**Table 1.** Summary of pathogenic bacteria removal on sand filters used in various studies.

occurring in the filter.

Desert sand, river sand, beach

Sand, d10 = 0.25 mm; d<sup>10</sup> = 0.40 mm; d10 = 0.63 mm

sand

*Escherichia coli* is commonly used in the assessment of sanitary condition of water and technological processes. This species is a mesophilous, non-spore forming facultative anaerobe capable of withstanding temperatures between 7 and 45°C and pH 4.7–9.5 [8]. *Escherichia coli* that belongs to the normal flora of the lower intestine in humans and warm-blooded animals may sometimes cause gastroenteritis. Detection of *E. coli* may indicate the presence of other, much more dangerous pathogenic bacteria, such as *Salmonella* sp. (causing typhoid or paratyphoid fever), *Shigella* sp.(causing dysentery) or *Vibrio cholerae* (causing cholera) [9].

It is therefore highly important to use such an on-site wastewater treatment system (OWTS) that is not only effective in removing organic and biogenic compounds but also protects the receiving water against bacterial contamination. Langenbach et al. [10, 11] suggested using a sand filter as a third stage of sewage treatment allowing for removing feces bacteria. A system comprising a settling tank and a sand filter with vertical flow seems to be more cost-effective solution that allows for highly efficient reduction of physical and chemical [12, 13], as well as bacteriological contamination. Using sand as the filter filling may result in elimination level of 1 × 102 –2 × 10<sup>4</sup> CFU/100 cm<sup>3</sup> for *Escherichia coli* and 5 × 10<sup>3</sup> –3 × 105 CFU/100 cm<sup>3</sup> for coliform bacteria [14–16]. Other media materials such as clay, zeolite and plastic fillings have also been widely used in wastewater treatment such as moving bed biofilm reactors, trickling filters, rotating biological contactors, etc., which address specific treatment requirements and enhance treatment efficiency.

This chapter discusses the application of natural fillings and plastic materials fillings for domestic sewage treatment. The chapter presents the possibility of using secondary and tertiary filters effective for ammonium and phosphorus ions removal and the pathogen bacteria removal. The effectiveness of one-layer filters and multi-layer filters during the secondary filtration of wastewater pre-treated in a septic tank is also presented.

## **2. The application of natural materials**

#### **2.1. The sand**

Effectiveness of the system comprising a septic tank and a sand filter with vertical flow is based on physical and chemical properties of the filter filling. Filtration is a technology commonly used to remove particulate matter and microbial contaminants in the processes of water treatment and sewage purification. It is based on retaining contaminants too big to get through water filled pores of a filter.

Effective operation of a sand filter involves also a formation of a biofilm called schmutzdecke on the top layer of the filter filling material [10, 11, 17–21]. This layer is formed at water and sand boundary and is made of biologically active microorganisms and other associated organic and inorganic substances. The biofilm may grow and reach from a few to a few dozen centimeters inside the bed [10, 11]. Quality of the treated sewage discharged from biosand filters (BSF) depends on sand grain size, filtration rate and intensity of biochemical processes occurring in the filter.

There are a number of pathogenic microorganisms transferred through water. They include rotaviruses and polioviruses, pathogenic bacteria or parasitic Protozoa (*Cryptosporidium sp.* oocysts and *Giardia sp.* cysts) [3, 4], as well as *an opportunistic pathogen Pseudomonas aeruginosa* [5–7]. The presence of pathogenic coliform bacteria (*Citrobacter sp., Enterobacter sp., Escherichia coli, Klebsiella sp.* and *Proteus sp.*) in aquatic environment indicates fresh contamination with

*Escherichia coli* is commonly used in the assessment of sanitary condition of water and technological processes. This species is a mesophilous, non-spore forming facultative anaerobe capable of withstanding temperatures between 7 and 45°C and pH 4.7–9.5 [8]. *Escherichia coli* that belongs to the normal flora of the lower intestine in humans and warm-blooded animals may sometimes cause gastroenteritis. Detection of *E. coli* may indicate the presence of other, much more dangerous pathogenic bacteria, such as *Salmonella* sp. (causing typhoid or paraty-

It is therefore highly important to use such an on-site wastewater treatment system (OWTS) that is not only effective in removing organic and biogenic compounds but also protects the receiving water against bacterial contamination. Langenbach et al. [10, 11] suggested using a sand filter as a third stage of sewage treatment allowing for removing feces bacteria. A system comprising a settling tank and a sand filter with vertical flow seems to be more cost-effective solution that allows for highly efficient reduction of physical and chemical [12, 13], as well as bacteriological contami-

materials such as clay, zeolite and plastic fillings have also been widely used in wastewater treatment such as moving bed biofilm reactors, trickling filters, rotating biological contactors, etc.,

This chapter discusses the application of natural fillings and plastic materials fillings for domestic sewage treatment. The chapter presents the possibility of using secondary and tertiary filters effective for ammonium and phosphorus ions removal and the pathogen bacteria removal. The effectiveness of one-layer filters and multi-layer filters during the secondary

Effectiveness of the system comprising a septic tank and a sand filter with vertical flow is based on physical and chemical properties of the filter filling. Filtration is a technology commonly used to remove particulate matter and microbial contaminants in the processes of water treatment and sewage purification. It is based on retaining contaminants too big to get

Effective operation of a sand filter involves also a formation of a biofilm called schmutzdecke on the top layer of the filter filling material [10, 11, 17–21]. This layer is formed at water and sand boundary and is made of biologically active microorganisms and other associated

–2 × 10<sup>4</sup> CFU/100 cm<sup>3</sup>

for coliform bacteria [14–16]. Other media

phoid fever), *Shigella* sp.(causing dysentery) or *Vibrio cholerae* (causing cholera) [9].

nation. Using sand as the filter filling may result in elimination level of 1 × 102

filtration of wastewater pre-treated in a septic tank is also presented.

**2. The application of natural materials**

through water filled pores of a filter.

–3 × 105 CFU/100 cm<sup>3</sup>

which address specific treatment requirements and enhance treatment efficiency.

urine and feces.

36 Sewage

for *Escherichia coli* and 5 × 10<sup>3</sup>

**2.1. The sand**

Heterotrophic bacteria that develop in an aerated sand bed are responsible for removing biodegradable organic substances as determined by BOD. As per literature reports, sand bed filtration of pre-treated wastewater allows for a removal of 92% of organic carbon [22] and a reduction of BOD by over 98% [14, 23–25]. An experiment by Wąsik et al. [25] showed that in a system septic tank/vertical filter with no additional aeration, filled with washed sand with equivalent grain diameter d10 = 0.62 mm, the removal of organic substances from domestic sewage was the most intense when the filter layers were 15 and 30 cm thick. Apart from heterotrophic bacteria, the sand filters in the presence of ammonium nitrogen are also colonized by nitrifying bacteria responsible for oxidation of ammonium nitrogen to nitrate nitrogen. White [22] reported 91% nitrification of sewage treated with sand filtering of secondary clarifier effluent. Chmielowski [14] demonstrated nitrification effectiveness for treatment of septic tank effluent to reach 92%. Chmielowski and Ślizowski claimed [12, 13] that equivalent diameter of sand bed grain exceeding 1.65 mm lowered sewage treatment effectiveness. Additionally, denitrification may occur in non-aerated zones of the filter. According to literature, the effectiveness of nitrate nitrogen removal in sand filters may be as high as 98% [23].

Properly designed vertical flow sand filters in the system with septic tank also provide a significant reduction of pathogenic bacteria count. In a field study on a technical scale, Chmielowski [14] received treated sewage containing 1 × 102 –1 × 10<sup>4</sup> CFU of *Escherichia coli* and on average 10 CFU of *Salmonella sp*. and *Shigella sp.* **Table 1** lists the effectiveness of pathogenic bacteria removal from wastewater on sand filters in various studies [26–30].

Langenbach et al. [10, 11] confirmed usability of a vertical flow sand filter in the removal of feces bacteria from secondary clarifier effluents over 59–148 days of the filter operation. They managed to reduced *Escherichia coli* count by ca. 2 log10 units, while medium count of the bacteria in the filtrate was not higher than 1 × 102 CFU/100 cm<sup>3</sup> . Such a good performance of


**Table 1.** Summary of pathogenic bacteria removal on sand filters used in various studies.

the filter depends on sand surface, determined by grain size distribution and filter height and on the schmutzdecke layer. In the sand filter, bacteria are slowly removed by their adhesion to the biofilm surface that coats the grains of the filler [31]. In an 8 week study with silica sand Accusand, Elliot et al. [17] found that the growth of schmutzdecke layer was the most important factor enhancing *Escherichia coli* removal by up to 5 log10 units from the drinking water mixed with wastewater. Jenkins et al. [32] reported an average removal of 1.8 log10 units, that is, 98.5% of fecal *coli* bacteria from a river water augmented with wastewater over 10 weeks in a filter filled with fine sand. They identified grain size as a major factor affecting the performance of sand filters. Similar conclusions were drawn by Wąsik and Chmielowski [15] who conducted semi-technical studies in biofilter models the operation of which in variable hydraulic conditions continued for 10–11 months. Observing variable hydraulic load of the filter surface that ranged from 16 to 64 mm∙d−1, the authors concluded that the degree of indicator bacteria removal was determined mostly by the range of filling grain size and not its percentage share or type. The filter filled with quartz sand with equivalent diameter d10 = 0.32 mm was found the most suitable for a reduction of bacterial contamination. The treated domestic sewage in a secondary level for OWTS had a very low count of *Escherichia coli* (102 –10<sup>3</sup> CFU). Filling the vertical filters with fine sand allowed for exceptional effective removal of the indicator bacteria by 41–4.8 log10 units, that is, 99.993–99.997% [16]. Similar values were given by Seeger et al. [30] who used a sand with equivalent diameter d10 = 0.21 mm.

used for sewage and water treatment include chalcedonite [35, 36] or expanded clay. Expanded clay is produced by heating clay loam. The expanded granules are oval and have a characteristic ceramic coating (bisque) on their surface. Inside the granules, there are evenly distributed small closed pores. Porosity of the material, however, depends on the number of open pores created in

Adsorption is a main mechanism of retaining bacteria by porous solids with pore diameter exceeding that of the bacterial cells. Adsorption of the bacterial cells to porous solids depends on three types of parameters: physical (carrier porosity, concentration of organic compounds, temperature and medium flow rate), chemical (ionic strength and pH) and microbiological (hydrophobicity and static charge on the surface of the bacterial cells) [38]. As the microorganisms are retained not only on the surface but also inside the pores, the resulting biofilm may

Masłoń and Tomaszek [39], who investigated non-granulated expanded clay as a biofilm carrier in *Moving Bed Sequencing Batch Biofilm Reactor*, observed unevenly developed biofilm in both open and closed pores of the filling. Expanded clay with a grain size of 4–8 mm facilitated a stable course of nitrification and a removal of up to 99% of ammonium nitrogen. Lekang and Kleppe [40] investigated a trickling filter filled with lightweight expanded clay aggregate (LECA) of three granule diameters: 2–4, 2–7 and 4–10 mm. After 7–8 weeks of LECA bed operation, 100% of ammonium nitrogen was removed irrespective of either granule size or filtration time.

Wąsik and Chmielowski [15] compared filters working with no additional aeration at variable hydraulic conditions filled with sand or non-granulated expanded clay and achieved ammonium nitrogen removal at the level of 52.4 and 68.4%, respectively. Domestic wastewa-

Jucherski and Nastawny [41] demonstrated that the use of expanded clay as a biofilm substrate for nitrification required optimization of the treatment process by reducing the organic

Treatment of domestic sewage in the expanded clay filled filter [16] allowed for 98.33% reduc-

granule size 1.0–2.5 mm facilitated reduction of indicator bacteria by ca. 4 log10 units to an

Natural zeolites are aluminosilicates with a skeletal structure comprising free spaces filled with ions and water molecules with high freedom of movement. They have net negative structural charge due to an isomorphic substitution of cations in crystal lattice [42, 43]. This nega-

affinity of phosphorus compounds to Ca, Fe or Al ions that were LECA components.

intensifies growth of heterotrophic bacteria that compete with nitrify-

–1 × 106 CFU/100 cm<sup>3</sup>

for *Escherichia coli* and 5.05 × 10<sup>4</sup> CFU/100 cm<sup>3</sup>

–1 × 106 CFU/100 cm<sup>3</sup>

∙d−1 and hydraulic retention time

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625 39

), and 99.71% reduc-

for coli-

). Fine expanded clay with

3− ions on expanded clay and did not show high

, which results in their high cation-exchange

the external ceramic coating or on the boundary of the bisque and granule body [37].

further increase the sorption of contaminants.

ter inflow changed over a few months from 250 to 2000 m<sup>3</sup>

ing bacteria and affect the removal of ammonium nitrogen.

Wąsik [71] achieved ca. 40% removal of PO<sup>4</sup>

tion of coliforms (to the mean level of 1 × 10<sup>3</sup>

tive charge is balanced by such cations as Na<sup>+</sup>

average level of 3.08 × 10<sup>3</sup> CFU/100 cm<sup>3</sup>

tion of *Escherichia coli* (to the mean level of 2 × 10<sup>4</sup>

(HRT) varied throughout the study from 1.8 to 56 days.

matter load. High BOD5

form bacteria [16].

**2.3. The zeolite**

The quality of biochemically treated sewage depends on microbial metabolism that slows down together with falling temperature. This is related, for example, to the climatic conditions occurring during the sewage treatment process. Kauppinen et al. [28] conducted a pilot study to evaluate annual efficacy of three different sand filters (SF) for the clarified raw municipal post-screen wastewater treatment operating in cold moderate climate. The SF with grain size of 0.8 mm removed on average 95.6% of BOD<sup>7</sup> . An additional biotite layer with grain size 0.2 mm increased this value up to 98.4%. Both filters provided a removal of ca. 30% nitrogen and ca. 78% phosphorus. Kauppinen et al. [28] confirmed that climatic conditions considerably affected the effectiveness of indicator bacteria and viruses removal. Sand filled filters retained on average 99.994% of *Escherichia coli*, and an additional biotite layer boosted this result to 99.999%. In winter, the values were reduced to 99.987 and 99.985%, respectively. Moreover, virus removal was also less effective in this season.

Aronino et al. [33] investigated the removal of viruses and noticed that a filtration of secondary effluents through a sand filter was associated with higher colloidal and organic loads. This caused a formation of a cake layer on the filter surface but did not change the kinetics of virus filtration process. Upper 40 cm of the filter served as a buffer layer, and actual filtration of the sewage occurred in the lower 60 cm layer of the filter. Microscopic studies confirmed that the size of the viruses was the only factor that determined their removal.

#### **2.2. The clay**

To improve biofilter performance, the sand filling may be partially or entirely replaced with porous materials. IUPAC (*International Union of Pure and Applied Chemistry*) defines porous materials as solid bodies with pores, cavities, channels or interstices that are deeper than they are wide [34]. Their adsorption capacity is determined by the internal structure of micropore systems, transition pores and macropores. Inexpensive solids with sorption properties strong enough to be used for sewage and water treatment include chalcedonite [35, 36] or expanded clay. Expanded clay is produced by heating clay loam. The expanded granules are oval and have a characteristic ceramic coating (bisque) on their surface. Inside the granules, there are evenly distributed small closed pores. Porosity of the material, however, depends on the number of open pores created in the external ceramic coating or on the boundary of the bisque and granule body [37].

Adsorption is a main mechanism of retaining bacteria by porous solids with pore diameter exceeding that of the bacterial cells. Adsorption of the bacterial cells to porous solids depends on three types of parameters: physical (carrier porosity, concentration of organic compounds, temperature and medium flow rate), chemical (ionic strength and pH) and microbiological (hydrophobicity and static charge on the surface of the bacterial cells) [38]. As the microorganisms are retained not only on the surface but also inside the pores, the resulting biofilm may further increase the sorption of contaminants.

Masłoń and Tomaszek [39], who investigated non-granulated expanded clay as a biofilm carrier in *Moving Bed Sequencing Batch Biofilm Reactor*, observed unevenly developed biofilm in both open and closed pores of the filling. Expanded clay with a grain size of 4–8 mm facilitated a stable course of nitrification and a removal of up to 99% of ammonium nitrogen. Lekang and Kleppe [40] investigated a trickling filter filled with lightweight expanded clay aggregate (LECA) of three granule diameters: 2–4, 2–7 and 4–10 mm. After 7–8 weeks of LECA bed operation, 100% of ammonium nitrogen was removed irrespective of either granule size or filtration time.

Wąsik and Chmielowski [15] compared filters working with no additional aeration at variable hydraulic conditions filled with sand or non-granulated expanded clay and achieved ammonium nitrogen removal at the level of 52.4 and 68.4%, respectively. Domestic wastewater inflow changed over a few months from 250 to 2000 m<sup>3</sup> ∙d−1 and hydraulic retention time (HRT) varied throughout the study from 1.8 to 56 days.

Jucherski and Nastawny [41] demonstrated that the use of expanded clay as a biofilm substrate for nitrification required optimization of the treatment process by reducing the organic matter load. High BOD5 intensifies growth of heterotrophic bacteria that compete with nitrifying bacteria and affect the removal of ammonium nitrogen.

Wąsik [71] achieved ca. 40% removal of PO<sup>4</sup> 3− ions on expanded clay and did not show high affinity of phosphorus compounds to Ca, Fe or Al ions that were LECA components.

Treatment of domestic sewage in the expanded clay filled filter [16] allowed for 98.33% reduction of *Escherichia coli* (to the mean level of 2 × 10<sup>4</sup> –1 × 106 CFU/100 cm<sup>3</sup> ), and 99.71% reduction of coliforms (to the mean level of 1 × 10<sup>3</sup> –1 × 106 CFU/100 cm<sup>3</sup> ). Fine expanded clay with granule size 1.0–2.5 mm facilitated reduction of indicator bacteria by ca. 4 log10 units to an average level of 3.08 × 10<sup>3</sup> CFU/100 cm<sup>3</sup> for *Escherichia coli* and 5.05 × 10<sup>4</sup> CFU/100 cm<sup>3</sup> for coliform bacteria [16].

#### **2.3. The zeolite**

the filter depends on sand surface, determined by grain size distribution and filter height and on the schmutzdecke layer. In the sand filter, bacteria are slowly removed by their adhesion to the biofilm surface that coats the grains of the filler [31]. In an 8 week study with silica sand Accusand, Elliot et al. [17] found that the growth of schmutzdecke layer was the most important factor enhancing *Escherichia coli* removal by up to 5 log10 units from the drinking water mixed with wastewater. Jenkins et al. [32] reported an average removal of 1.8 log10 units, that is, 98.5% of fecal *coli* bacteria from a river water augmented with wastewater over 10 weeks in a filter filled with fine sand. They identified grain size as a major factor affecting the performance of sand filters. Similar conclusions were drawn by Wąsik and Chmielowski [15] who conducted semi-technical studies in biofilter models the operation of which in variable hydraulic conditions continued for 10–11 months. Observing variable hydraulic load of the filter surface that ranged from 16 to 64 mm∙d−1, the authors concluded that the degree of indicator bacteria removal was determined mostly by the range of filling grain size and not its percentage share or type. The filter filled with quartz sand with equivalent diameter d10 = 0.32 mm was found the most suitable for a reduction of bacterial contamination. The treated domestic

sewage in a secondary level for OWTS had a very low count of *Escherichia coli* (102

Seeger et al. [30] who used a sand with equivalent diameter d10 = 0.21 mm.

grain size of 0.8 mm removed on average 95.6% of BOD<sup>7</sup>

Moreover, virus removal was also less effective in this season.

size of the viruses was the only factor that determined their removal.

**2.2. The clay**

38 Sewage

Filling the vertical filters with fine sand allowed for exceptional effective removal of the indicator bacteria by 41–4.8 log10 units, that is, 99.993–99.997% [16]. Similar values were given by

The quality of biochemically treated sewage depends on microbial metabolism that slows down together with falling temperature. This is related, for example, to the climatic conditions occurring during the sewage treatment process. Kauppinen et al. [28] conducted a pilot study to evaluate annual efficacy of three different sand filters (SF) for the clarified raw municipal post-screen wastewater treatment operating in cold moderate climate. The SF with

grain size 0.2 mm increased this value up to 98.4%. Both filters provided a removal of ca. 30% nitrogen and ca. 78% phosphorus. Kauppinen et al. [28] confirmed that climatic conditions considerably affected the effectiveness of indicator bacteria and viruses removal. Sand filled filters retained on average 99.994% of *Escherichia coli*, and an additional biotite layer boosted this result to 99.999%. In winter, the values were reduced to 99.987 and 99.985%, respectively.

Aronino et al. [33] investigated the removal of viruses and noticed that a filtration of secondary effluents through a sand filter was associated with higher colloidal and organic loads. This caused a formation of a cake layer on the filter surface but did not change the kinetics of virus filtration process. Upper 40 cm of the filter served as a buffer layer, and actual filtration of the sewage occurred in the lower 60 cm layer of the filter. Microscopic studies confirmed that the

To improve biofilter performance, the sand filling may be partially or entirely replaced with porous materials. IUPAC (*International Union of Pure and Applied Chemistry*) defines porous materials as solid bodies with pores, cavities, channels or interstices that are deeper than they are wide [34]. Their adsorption capacity is determined by the internal structure of micropore systems, transition pores and macropores. Inexpensive solids with sorption properties strong enough to be

–10<sup>3</sup> CFU).

. An additional biotite layer with

Natural zeolites are aluminosilicates with a skeletal structure comprising free spaces filled with ions and water molecules with high freedom of movement. They have net negative structural charge due to an isomorphic substitution of cations in crystal lattice [42, 43]. This negative charge is balanced by such cations as Na<sup>+</sup> , which results in their high cation-exchange capacity, for example, toward ammonium ions NH<sup>4</sup> + . Apart from their ion-exchange properties, zeolites have also excellent sorption capacity. Efficiency of contamination removal with zeolites is determined by zeolite chemical composition, granule size, hydraulic load, concentration of the removed ions and pH of the reaction environment [44, 45].

compounds. A comparison of ammonium nitrogen removal with zeolite and bentonite identi-

other authors, that is, 0.4–25.5 mg∙g−1 of the sorbent [40, 66, 68]. A study by Wąsik et al. [69] showed higher efficiency of zeolite than sand filters in removing biogenic compounds from domestic sewage. The use of zeolite allowed for effective average elimination of ammonium

Ferronato et al. [62] investigated the capability of granulated clinoptilolite manufactured by

(24 h) experiment, they evaluated the adsorption rate of clinoptilolite in a laminar flow bed.

respectively, while the concentration of ammonium ions was 13.9 mg∙dm−3. The experiment

ability of clinoptilolite binding sites for these ions. High degree of ammonium ion adsorption in clinoptilolite bed was in line with the data reported by other authors [70]. A reduced count of pathogenic microorganisms was also observed, by 90.4–95.2% for *Escherichia coli* and

According to the literature, the processes of filtration and adsorption control immobilization of pathogenic bacteria contained in the sewage flowing through a porous substrate [11, 38]. The first mechanism is highly controlled by the size of the filter filling. Stevik [38] reported that the effectiveness of bacteria retention due to filtration was inversely proportional to the grain size of a filtration material. Adsorption is the main mechanism of bacteria retention in porous media with pore diameter larger than the bacteria. As the microorganisms are retained not only on the surface but also inside the pores, the resulting biofilm may serve as an additional sorbent and increase adhesion of the bacterial contaminants. Natural zeolites are capable of entrapping microorganisms thanks to micropores [71], Van der Waals forces, hydrogen bonding or ion bridging [71–73]. Additionally, selective, positively charged materials may attract Gram-negative bacteria such as *Escherichia coli* [74, 75]. However, it should be taken into account that soluble organic compounds contained in the sewage may block the

Wąsik and Chmielowski [16] reported an increased count of pathogenic bacteria in treated wastewater together with increasing size of zeolite granules. Enlarging the zeolite equivalent diameter d10 from 1.0 to 3.6 mm resulted in rising the count of *Escherichia coli* and coli-

New solutions based on biological beds filled with porous or modified materials often increase the efficiency of wastewater treatment but they may be inadequate in terms of their microbiological quality. Therefore, supplementation of the porous materials with a layer of quartz sand seems a simple solution to this problem. Quartz sand is inexpensive and provides an effective barrier for the pathogenic bacteria. A study by Kanawade [77] focused on using a multi-layer filter to

to 8.67 × 10<sup>3</sup> CFU/100 cm<sup>3</sup>

. The highest removal rate of pathogenic bacteria at the level of 99.995%

substrate surface and consequently the charges that attract *Escherichia coli* [76].

+

+

removal was within the range for natural zeolite reported by

+

∙g−1, as 11% more effective than bentonite.

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625

from wastewater. In a short-term

from 0.3 to 0.06 mg/g/l due to the avail-

and 1.77 × 105 CFU/100 cm<sup>3</sup>

and from 1.85 × 10<sup>4</sup>

to

,

41

fied zeolite, with absorption level of 7.80 mg N-NH<sup>4</sup>

nitrogen (73.31%) and orthophosphates (62.93%).

demonstrated a decrease in the adsorption of NH<sup>4</sup>

form bacteria, respectively, from 5.75 × 102

was observed for zeolite with granule size 1.0–2.5 mm.

3.47 × 10<sup>4</sup> CFU/100 cm<sup>3</sup>

**2.4. Multi-layer filters**

+

ECOLIN in removing pathogenic microorganisms and NH<sup>4</sup>

The initial count of *Escherichia coli* and total coliform was 1.2 × 105

This effectiveness of N-NH<sup>4</sup>

89.9–94.8% for total coliforms.

The most common natural zeolite is clinoptilolite with molecular formula (Na,K,Ca)2- 3 Al<sup>3</sup> (Al,Si)2 Si13O36∙12H2 O [46]. Due to their considerable ion-exchange and adsorption capacity, clinoptilolites are mainly used to remove NH<sup>4</sup> + from water [47–51] and sewage [52–58]. Clinoptilolites may replace quartz sand and their selective properties may be successfully used to filter water or sewage. Clinoptilolite filled filters help in cleaning water not only from ammonium nitrogen but also from suspended solids, colloidal particles or bacteria. **Table 2** presents ammonium exchange capacities of clinoptilolites used for wastewater treatment in various studies [58–65].

Effectiveness of ammonium ion removal depends on the type and dose of the zeolite, time of its exposure to sewage, temperature, pH and the presence of other anions and cations in the solution [66]. Kalló [67] showed a removal of ammonium nitrogen from biologically treated wastewater via ion exchange in a column filled with Hungarian clinoptilolite with granule size 0.5–2.0 mm. The author reported that in the column filled with 0.5–1.6 mm granules, the ion exchange was controlled by diffusion as the ion-exchange rate increased for smaller granule sizes.

Wiśniowska et al. [63] evaluated zeolite suitability as a supportive measure of nitrogen removal in the systems based on activated sludge. They concluded that zeolite was an effective sorbent in emergency situations as it prevented disturbances in the removal of biogenic


**Table 2.** Summary of ammonium ions sorption capacities of zeolites used in various studies.

compounds. A comparison of ammonium nitrogen removal with zeolite and bentonite identified zeolite, with absorption level of 7.80 mg N-NH<sup>4</sup> + ∙g−1, as 11% more effective than bentonite. This effectiveness of N-NH<sup>4</sup> + removal was within the range for natural zeolite reported by other authors, that is, 0.4–25.5 mg∙g−1 of the sorbent [40, 66, 68]. A study by Wąsik et al. [69] showed higher efficiency of zeolite than sand filters in removing biogenic compounds from domestic sewage. The use of zeolite allowed for effective average elimination of ammonium nitrogen (73.31%) and orthophosphates (62.93%).

Ferronato et al. [62] investigated the capability of granulated clinoptilolite manufactured by ECOLIN in removing pathogenic microorganisms and NH<sup>4</sup> + from wastewater. In a short-term (24 h) experiment, they evaluated the adsorption rate of clinoptilolite in a laminar flow bed. The initial count of *Escherichia coli* and total coliform was 1.2 × 105 and 1.77 × 105 CFU/100 cm<sup>3</sup> , respectively, while the concentration of ammonium ions was 13.9 mg∙dm−3. The experiment demonstrated a decrease in the adsorption of NH<sup>4</sup> + from 0.3 to 0.06 mg/g/l due to the availability of clinoptilolite binding sites for these ions. High degree of ammonium ion adsorption in clinoptilolite bed was in line with the data reported by other authors [70]. A reduced count of pathogenic microorganisms was also observed, by 90.4–95.2% for *Escherichia coli* and 89.9–94.8% for total coliforms.

According to the literature, the processes of filtration and adsorption control immobilization of pathogenic bacteria contained in the sewage flowing through a porous substrate [11, 38]. The first mechanism is highly controlled by the size of the filter filling. Stevik [38] reported that the effectiveness of bacteria retention due to filtration was inversely proportional to the grain size of a filtration material. Adsorption is the main mechanism of bacteria retention in porous media with pore diameter larger than the bacteria. As the microorganisms are retained not only on the surface but also inside the pores, the resulting biofilm may serve as an additional sorbent and increase adhesion of the bacterial contaminants. Natural zeolites are capable of entrapping microorganisms thanks to micropores [71], Van der Waals forces, hydrogen bonding or ion bridging [71–73]. Additionally, selective, positively charged materials may attract Gram-negative bacteria such as *Escherichia coli* [74, 75]. However, it should be taken into account that soluble organic compounds contained in the sewage may block the substrate surface and consequently the charges that attract *Escherichia coli* [76].

Wąsik and Chmielowski [16] reported an increased count of pathogenic bacteria in treated wastewater together with increasing size of zeolite granules. Enlarging the zeolite equivalent diameter d10 from 1.0 to 3.6 mm resulted in rising the count of *Escherichia coli* and coliform bacteria, respectively, from 5.75 × 102 to 8.67 × 10<sup>3</sup> CFU/100 cm<sup>3</sup> and from 1.85 × 10<sup>4</sup> to 3.47 × 10<sup>4</sup> CFU/100 cm<sup>3</sup> . The highest removal rate of pathogenic bacteria at the level of 99.995% was observed for zeolite with granule size 1.0–2.5 mm.

#### **2.4. Multi-layer filters**

capacity, for example, toward ammonium ions NH<sup>4</sup>

ity, clinoptilolites are mainly used to remove NH<sup>4</sup>

3 Al<sup>3</sup>

40 Sewage

P1 zeolite K-F zeolite

(mixture)

K-Chabazite/K-Phillipsite zeolite

Nanozeolite - palygorskite

Commercial zeolite 13X

Fly ash zeolite

nanocomposite

(Al,Si)2

various studies [58–65].

Si13O36∙12H2

+

+

O [46]. Due to their considerable ion-exchange and adsorption capac-

ties, zeolites have also excellent sorption capacity. Efficiency of contamination removal with zeolites is determined by zeolite chemical composition, granule size, hydraulic load, concen-

The most common natural zeolite is clinoptilolite with molecular formula (Na,K,Ca)2-

Clinoptilolites may replace quartz sand and their selective properties may be successfully used to filter water or sewage. Clinoptilolite filled filters help in cleaning water not only from ammonium nitrogen but also from suspended solids, colloidal particles or bacteria. **Table 2** presents ammonium exchange capacities of clinoptilolites used for wastewater treatment in

Effectiveness of ammonium ion removal depends on the type and dose of the zeolite, time of its exposure to sewage, temperature, pH and the presence of other anions and cations in the solution [66]. Kalló [67] showed a removal of ammonium nitrogen from biologically treated wastewater via ion exchange in a column filled with Hungarian clinoptilolite with granule size 0.5–2.0 mm. The author reported that in the column filled with 0.5–1.6 mm granules, the ion exchange was

Wiśniowska et al. [63] evaluated zeolite suitability as a supportive measure of nitrogen removal in the systems based on activated sludge. They concluded that zeolite was an effective sorbent in emergency situations as it prevented disturbances in the removal of biogenic

Wastewater 0.1–0.18 meq NH<sup>4</sup>

+ /g

+ /g

+

+

+

+

12.5–44.3 mg NH<sup>4</sup>

131.04–184.8 mg NH<sup>4</sup>

115.36–155.68 mg NH<sup>4</sup>

+ /g Juan et al. 2009 [61]

/g Zabochnicka-Swiatek and Malinska 2010 [59]

/g Widiastuti et al. 2011 [58]

/g Wang et al. 2014 [61]

/g Ferronato et al. 2015 [62]

/dm<sup>3</sup> Turan 2016 [64]

/dm<sup>3</sup>

/dm<sup>3</sup>

/g Wisniowska et al. 2015 [63]

Das et al. 2017 [75]

0.09–0.15 meq NH<sup>4</sup>

0.1–0.16 meq NH<sup>4</sup>

237.6 mg NH<sup>4</sup>

+

controlled by diffusion as the ion-exchange rate increased for smaller granule sizes.

**Type of zeolite Medium Sorption capacity References**

Hungarian clinoptilolite Wastewater 3.79 mg NH<sup>4</sup>

Zeolite type A-carbon Greywater 115.213 mg NH<sup>4</sup>

Clinoptilolite ECOLIN Wastewater 0.3 mg NH<sup>4</sup>

Synthetic zeolite Synthetic

Clinoptilolite Wastewater 7.80 mg N-NH<sup>4</sup>

Synthetic wastewater

wastewater

Synthetic wastewater

**Table 2.** Summary of ammonium ions sorption capacities of zeolites used in various studies.

tration of the removed ions and pH of the reaction environment [44, 45].

. Apart from their ion-exchange proper-

from water [47–51] and sewage [52–58].

New solutions based on biological beds filled with porous or modified materials often increase the efficiency of wastewater treatment but they may be inadequate in terms of their microbiological quality. Therefore, supplementation of the porous materials with a layer of quartz sand seems a simple solution to this problem. Quartz sand is inexpensive and provides an effective barrier for the pathogenic bacteria. A study by Kanawade [77] focused on using a multi-layer filter to remove ammonium and suspended solids from effluents of a domestic wastewater plant. The filter was filled with sand of grain size 0.5−1.0 mm that filtered out suspended solids and the top layer was made of clinoptilolite that removed ammonium nitrogen. Turkish clinoptilolite with adsorption capability of 10.4 mg∙g−1 was used. As a result, 100% of ammonium nitrogen and 75% of suspended solids were removed by the multi-layer filter over 38 hours of its operation.

authors claimed materials such as organic fiber, synthetic foam or textile to be more economically advantageous. Systems based on non-mineral materials may be smaller than filters filled with mineral materials. Several systems based on the use of artificial materials sold by commercial vendors have been approved for use in Virginia. Non-mineral media systems can be prefabricated, transported and assembled locally from modules, while mineral-filled filters

Harwanto et al. [89] evaluated the use of a polystyrene microbead filter (PF) and Kaldnes filter (KF) in trickle filters. They determined mean efficiency of ammonium ion removal to be 35.0–310.5 g∙m−3d−1 for PF and 32.1–288.1 g∙m−3d−1 for KF. Nijhof [90], who investigated the efficiency of a leaching system filled with Filterpack CR50 Mass Transfer filling

0.8 g∙m−2d−1. Moulick et al. [91] used nylon pot scrubber media as a filling in trickling filters. They reported 28–68% efficiency of ammonia removal and nitrification indices within

Kishimoto et al. [92] researched nitrification efficiency in restaurant wastewater treated in trickling filters filled with plastic media of the same material, the same shape but different roughness. One media type had a smooth surface (KT-15, Dainippon Plastics, Japan) and the other a rough surface (LT-15, Dainippon Plastics, Japan). They found that the removal of organic compounds (defined as COD) and nitrification were more effective in rough surface media filling (LT-15) than in smooth surface media filling (KT-15). Better performance of LT-15 filling was concluded to be due to twice larger biomass of microorganisms attached to this media.

Stephenson et al. [93] examined eight different plastic media (acrylonitrile butadiene styrene, nylon, polycarbonate, polyethylene, polypropylene, polytetraflouroethylene (PTFE), polyvinyl chloride and tufnol) in a reactor receiving settled domestic wastewater. They found that nitrification rates did not correlate with biomass concentration or surface roughness of the media. The use of PTFE, that is, a material with the lowest surface adhesion force, allowed for

Wąsik and Chmielowski [15] determined the effects of ammonia and indicator bacteria removal during the treatment of domestic sewage on a vertical flow filter filled with plastic material (PET flakes). The experiments were performed in previously developed models that continuously

retention time (HRT) from 1.8 to 56 days. PET flakes provided favorable conditions for nitrifying bacteria, as mean ammonium nitrogen removal rate for this material was 66.74%. The filters with plastic filling reduced the count of *Escherichia coli* by 98.08% and of coliform bacteria by 98.41%.

The calcined limestone-silicate rock is formed in a thermal processing as a result of calcium carbonate decomposition to calcium oxide and carbon dioxide. The process is associated with an increase in sorption capacity of limestone-silicate rock (so called gaize) from 19.6to 119.6 g P∙kg−1 for the material burnt at 1000°C [94]. The presence of calcium ions and high pH make the calcined

development of a biofilm with the highest nitrification rate of 1.5 g∙m−1d−1.

operated for a few months at variable hydraulical conditions (250–2000 cm<sup>3</sup>

**4. The calcined limestone-silicate rock**

∙m−3, established the nitrification index as ranging from 0.1 to

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625 43

∙d−1) and hydraulic

are typically built on-site.

with specific area of 200 m2

the range 0.11–1.29 g∙m−2d−1.

Kalenik [78] investigated treatment of model wastewater in a sandy soil bed with a layer of clinoptilolite. He showed that phosphorus removal efficiency was 53.1% in a 0.10 m thick layer and as high as 89.2% when the bed was 0.20 m thick. The use of medium sand alone (without additional layer of clinoptilolite) allowed for a removal of 23% of total phosphorus.

Syafalni et al. [79] filtrated dyed wastewater on granular activated carbon (GAC) and zeolite with particle size range of 1.18–2.00 mm. A filter comprising GAC as a top layer and zeolite as a bottom layer removed 59.46% COD, 60.82% of ammonia and 58.4% of the dye.

Wąsik and Chmielowski [80, 81] investigated a multi-layer filter filled with sand and granulated activated carbon exposed to variable hydraulic load (from 43 to 88 mm∙d−1). They noticed huge variations in the efficiency of reduction of BOD5 (6–99%), CODCr (31–90%) and total suspended solids (55–95%) due to variable conditions prevailing in individual layers of the filter. They concluded that a monolayer filter filled with granulated activated carbon was the most suitable for treatment of domestic sewage over a 3-month study cycle. Average efficiency of BOD5 , CODCr and suspended solids elimination was very high irrespective of rising hydraulic load and reached, respectively, 98, 97 and 87%. This was consistent with the reports of other authors on biologically active carbon filters [82, 83]. Mean efficiency of bacterial elimination in a two-layer filter comprising 75% of fine sand (d10 = 0.32 mm) in its bottom layer and 25% of fine zeolite (d10 = 1.8 mm) in the top layer was 97% for BOD5 , 92% for CODCr, 99.993% for *Escherichia coli* and 99.953% for other coliform bacteria.

#### **3. Plastic materials**

Natural materials commonly used as a filling for biological systems may be replaced with a plastic filling. Compared with conventional media (quartz sand, gravel, clay and rock) plastic fillings have high specific surface area and lower tendency to clogging. Modern biological filters have a large specific area of up to 150–200 m2 /m<sup>3</sup> (filter media in trickling filters), which provides more space for growth of heterotrophic and nitrifying bacteria [84]. Reportedly, the plastic media in a Moving Bed Biofilm Reactor present up to 1200 m2 /m<sup>3</sup> specific area [85].

Plastic filter media are light and can be constructed to greater depths, thus increasing the hydraulic load capacity and improving mass transfer. Plastic fillings are characterized by the highest abrasion resistance and better gas transfer due to the greater draft [86, 87]. Filters with natural filling, such as rock or sand are often poorly aerated as they contain less empty/hollow fractions [66]. Currently used plastic fillings of biological systems are produced as random or modular packing media.

Galbraith et al. [88] discussed high costs of obtaining molten mineral material, that is, sand of grain size suitable for a construction of filters meeting legal requirements (VDH 2011). The authors claimed materials such as organic fiber, synthetic foam or textile to be more economically advantageous. Systems based on non-mineral materials may be smaller than filters filled with mineral materials. Several systems based on the use of artificial materials sold by commercial vendors have been approved for use in Virginia. Non-mineral media systems can be prefabricated, transported and assembled locally from modules, while mineral-filled filters are typically built on-site.

Harwanto et al. [89] evaluated the use of a polystyrene microbead filter (PF) and Kaldnes filter (KF) in trickle filters. They determined mean efficiency of ammonium ion removal to be 35.0–310.5 g∙m−3d−1 for PF and 32.1–288.1 g∙m−3d−1 for KF. Nijhof [90], who investigated the efficiency of a leaching system filled with Filterpack CR50 Mass Transfer filling with specific area of 200 m2 ∙m−3, established the nitrification index as ranging from 0.1 to 0.8 g∙m−2d−1. Moulick et al. [91] used nylon pot scrubber media as a filling in trickling filters. They reported 28–68% efficiency of ammonia removal and nitrification indices within the range 0.11–1.29 g∙m−2d−1.

Kishimoto et al. [92] researched nitrification efficiency in restaurant wastewater treated in trickling filters filled with plastic media of the same material, the same shape but different roughness. One media type had a smooth surface (KT-15, Dainippon Plastics, Japan) and the other a rough surface (LT-15, Dainippon Plastics, Japan). They found that the removal of organic compounds (defined as COD) and nitrification were more effective in rough surface media filling (LT-15) than in smooth surface media filling (KT-15). Better performance of LT-15 filling was concluded to be due to twice larger biomass of microorganisms attached to this media.

Stephenson et al. [93] examined eight different plastic media (acrylonitrile butadiene styrene, nylon, polycarbonate, polyethylene, polypropylene, polytetraflouroethylene (PTFE), polyvinyl chloride and tufnol) in a reactor receiving settled domestic wastewater. They found that nitrification rates did not correlate with biomass concentration or surface roughness of the media. The use of PTFE, that is, a material with the lowest surface adhesion force, allowed for development of a biofilm with the highest nitrification rate of 1.5 g∙m−1d−1.

Wąsik and Chmielowski [15] determined the effects of ammonia and indicator bacteria removal during the treatment of domestic sewage on a vertical flow filter filled with plastic material (PET flakes). The experiments were performed in previously developed models that continuously operated for a few months at variable hydraulical conditions (250–2000 cm<sup>3</sup> ∙d−1) and hydraulic retention time (HRT) from 1.8 to 56 days. PET flakes provided favorable conditions for nitrifying bacteria, as mean ammonium nitrogen removal rate for this material was 66.74%. The filters with plastic filling reduced the count of *Escherichia coli* by 98.08% and of coliform bacteria by 98.41%.

## **4. The calcined limestone-silicate rock**

remove ammonium and suspended solids from effluents of a domestic wastewater plant. The filter was filled with sand of grain size 0.5−1.0 mm that filtered out suspended solids and the top layer was made of clinoptilolite that removed ammonium nitrogen. Turkish clinoptilolite with adsorption capability of 10.4 mg∙g−1 was used. As a result, 100% of ammonium nitrogen and 75% of suspended solids were removed by the multi-layer filter over 38 hours of its operation.

Kalenik [78] investigated treatment of model wastewater in a sandy soil bed with a layer of clinoptilolite. He showed that phosphorus removal efficiency was 53.1% in a 0.10 m thick layer and as high as 89.2% when the bed was 0.20 m thick. The use of medium sand alone (without additional layer of clinoptilolite) allowed for a removal of 23% of total phosphorus. Syafalni et al. [79] filtrated dyed wastewater on granular activated carbon (GAC) and zeolite with particle size range of 1.18–2.00 mm. A filter comprising GAC as a top layer and zeolite as

Wąsik and Chmielowski [80, 81] investigated a multi-layer filter filled with sand and granulated activated carbon exposed to variable hydraulic load (from 43 to 88 mm∙d−1). They noticed

pended solids (55–95%) due to variable conditions prevailing in individual layers of the filter. They concluded that a monolayer filter filled with granulated activated carbon was the most suitable for treatment of domestic sewage over a 3-month study cycle. Average efficiency of

Natural materials commonly used as a filling for biological systems may be replaced with a plastic filling. Compared with conventional media (quartz sand, gravel, clay and rock) plastic fillings have high specific surface area and lower tendency to clogging. Modern biological

provides more space for growth of heterotrophic and nitrifying bacteria [84]. Reportedly, the

Plastic filter media are light and can be constructed to greater depths, thus increasing the hydraulic load capacity and improving mass transfer. Plastic fillings are characterized by the highest abrasion resistance and better gas transfer due to the greater draft [86, 87]. Filters with natural filling, such as rock or sand are often poorly aerated as they contain less empty/hollow fractions [66]. Currently used plastic fillings of biological systems are produced as random or

Galbraith et al. [88] discussed high costs of obtaining molten mineral material, that is, sand of grain size suitable for a construction of filters meeting legal requirements (VDH 2011). The

/m<sup>3</sup>

, CODCr and suspended solids elimination was very high irrespective of rising hydraulic load and reached, respectively, 98, 97 and 87%. This was consistent with the reports of other authors on biologically active carbon filters [82, 83]. Mean efficiency of bacterial elimination in a two-layer filter comprising 75% of fine sand (d10 = 0.32 mm) in its bottom layer and 25%

(6–99%), CODCr (31–90%) and total sus-

, 92% for CODCr, 99.993% for

(filter media in trickling filters), which

specific area [85].

/m<sup>3</sup>

a bottom layer removed 59.46% COD, 60.82% of ammonia and 58.4% of the dye.

huge variations in the efficiency of reduction of BOD5

of fine zeolite (d10 = 1.8 mm) in the top layer was 97% for BOD5

plastic media in a Moving Bed Biofilm Reactor present up to 1200 m2

*Escherichia coli* and 99.953% for other coliform bacteria.

filters have a large specific area of up to 150–200 m2

BOD5

42 Sewage

**3. Plastic materials**

modular packing media.

The calcined limestone-silicate rock is formed in a thermal processing as a result of calcium carbonate decomposition to calcium oxide and carbon dioxide. The process is associated with an increase in sorption capacity of limestone-silicate rock (so called gaize) from 19.6to 119.6 g P∙kg−1 for the material burnt at 1000°C [94]. The presence of calcium ions and high pH make the calcined rock suitable for the removal of phosphorus compounds. Alkaline environment (pH ca. 8) facilitates binding of orthophosphate ions by calcium ions and formation of hydroxyapatite crystals. Renman [95] confirmed the presence of amorphous tricalcium phosphate in an exhausted filter filling commercially known as Polonite®. She also demonstrated that 82% of the exhausted filling was calcium and phosphorus compounds in the form of hydroxyapatite.

nitrogen. The study revealed also a considerable (73–74%) dependency between the reduction of coliform count and biogenic compounds. Authors claimed that alkalization of the environ-

calcium ions as well as carbonates and coliform bacteria created suitable conditions to the

tals. The formation of struvite crystals by microorganisms in the presence of ammonia ions and magnesium phosphate was first described by Robinson [104]. Struvite is spontaneously precipitated during domestic sewage treatment [105] in the presence of high concentration of soluble phosphorus, ammonium and magnesium, and low concentration of total suspension solids and alkaline pH. If the formation and accumulation of struvite was controlled, it could

Wąsik et al. [103] showed that microscopic examination of sediment samples taken from the surface and interior of the filter confirmed the formation of magnesium ammonium phosphate (struvite) and apatite crystals. The crystallization process was carried out both on the surface and inside of the bacterial cells and total elimination of the coliform bacteria confirmed their role as nuclei of crystallization. Microscopic research confirmed tricalcium phos-

Statistical tools helps us analyze the data generated in lab scale systems and full scale installations, and are able to identify the critical factors that govern the process treatment efficiencies,

Variance analysis ANOVA performed by Wąsik [69] identified selectivity, porosity and grain size of the filling as the factors responsible for effective removal of ammonium nitrogen, orthophosphates and *Escherichia coli* and coliform bacteria from domestic sewage treated in a septic tank and a vertical flow filter. Natural selective and porous materials were found to be the most effective in the removal of biogenic compounds. The filling of grain size from 1.0 to 2.5 mm provided highly efficient removal of ammonium (75.34%) and orthophosphate (>79%) ions. The filter filled with natural porous material of fine grain size was the most suitable for removing pathogenic bacteria, and allowed for elimination of 99.98% of *Escherichia coli* and 99.94% of coliform bacteria. Wąsik and Chmielowski [15, 16] used the principal component analysis (PCA) to determine the mechanisms of pathogenic bacteria removal. PCA showed that in the case of natural materials the effectiveness of *Escherichia coli* elimination depends mainly on the filling grain size

Treatment of domestic sewage in the areas with scattered development remains a serious issue. Discharging ineffectively treated sewage into the environment may cause an increase in the count of pathogenic organisms. In developing countries, where water and sanitation

O) and apatite Ca5

and PO<sup>4</sup>

(PO34)<sup>3</sup>

3− in the presence of magnesium and

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625

> (PO<sup>4</sup> )3 ∙CO<sup>3</sup>

crys-

45

∙OH and Ca5

+

ment and chemical reactions involving NH<sup>4</sup>

phates were more abundant than struvite.

**5. The importance of statistical tools**

and not the filling type.

**6. Summary**

PO<sup>4</sup> ∙6H2

have a market potential as a slow release fertilizer [106, 107].

and provide engineering design guidance with confidence.

formation of struvite (MgNH<sup>4</sup>

Most studies investigating the use of calcined rock focused on the removal of phosphates [96, 97]. **Table 3** presents the use of limestone-silicate rock or its calcined form in the removal of phosphate ions as reported by various researchers [98–101]. In their study on the use of calcined rock (Polonite®) in the removal of phosphates from wastewater, Renman et al. [98, 102] noticed also about 18% removal of inorganic forms of nitrogen, which they considered to be losses associated with their evaporation.

An experiment of Wąsik et al. [103] investigating the use of calcined rock as a filling of a vertical flow filter operating under variable hydraulic retention time (HRT) identified chemical processes, and not biofiltration, as the basic cause of PO<sup>4</sup> 3− and NH<sup>4</sup> + removal. A few months long filtration of pre-treated domestic sewage through calcined limestone-silicate rock revealed a very high (95%) positive correlation between the removal of phosphates and ammonium


**Table 3.** Summary of phosphorus ions sorption capacities for carbonate-silica rocks used in various studies.

nitrogen. The study revealed also a considerable (73–74%) dependency between the reduction of coliform count and biogenic compounds. Authors claimed that alkalization of the environment and chemical reactions involving NH<sup>4</sup> + and PO<sup>4</sup> 3− in the presence of magnesium and calcium ions as well as carbonates and coliform bacteria created suitable conditions to the formation of struvite (MgNH<sup>4</sup> PO<sup>4</sup> ∙6H2 O) and apatite Ca5 (PO34)<sup>3</sup> ∙OH and Ca5 (PO<sup>4</sup> )3 ∙CO<sup>3</sup> crystals. The formation of struvite crystals by microorganisms in the presence of ammonia ions and magnesium phosphate was first described by Robinson [104]. Struvite is spontaneously precipitated during domestic sewage treatment [105] in the presence of high concentration of soluble phosphorus, ammonium and magnesium, and low concentration of total suspension solids and alkaline pH. If the formation and accumulation of struvite was controlled, it could have a market potential as a slow release fertilizer [106, 107].

Wąsik et al. [103] showed that microscopic examination of sediment samples taken from the surface and interior of the filter confirmed the formation of magnesium ammonium phosphate (struvite) and apatite crystals. The crystallization process was carried out both on the surface and inside of the bacterial cells and total elimination of the coliform bacteria confirmed their role as nuclei of crystallization. Microscopic research confirmed tricalcium phosphates were more abundant than struvite.

## **5. The importance of statistical tools**

Statistical tools helps us analyze the data generated in lab scale systems and full scale installations, and are able to identify the critical factors that govern the process treatment efficiencies, and provide engineering design guidance with confidence.

Variance analysis ANOVA performed by Wąsik [69] identified selectivity, porosity and grain size of the filling as the factors responsible for effective removal of ammonium nitrogen, orthophosphates and *Escherichia coli* and coliform bacteria from domestic sewage treated in a septic tank and a vertical flow filter. Natural selective and porous materials were found to be the most effective in the removal of biogenic compounds. The filling of grain size from 1.0 to 2.5 mm provided highly efficient removal of ammonium (75.34%) and orthophosphate (>79%) ions. The filter filled with natural porous material of fine grain size was the most suitable for removing pathogenic bacteria, and allowed for elimination of 99.98% of *Escherichia coli* and 99.94% of coliform bacteria.

Wąsik and Chmielowski [15, 16] used the principal component analysis (PCA) to determine the mechanisms of pathogenic bacteria removal. PCA showed that in the case of natural materials the effectiveness of *Escherichia coli* elimination depends mainly on the filling grain size and not the filling type.

#### **6. Summary**

rock suitable for the removal of phosphorus compounds. Alkaline environment (pH ca. 8) facilitates binding of orthophosphate ions by calcium ions and formation of hydroxyapatite crystals. Renman [95] confirmed the presence of amorphous tricalcium phosphate in an exhausted filter filling commercially known as Polonite®. She also demonstrated that 82% of the exhausted filling

Most studies investigating the use of calcined rock focused on the removal of phosphates [96, 97]. **Table 3** presents the use of limestone-silicate rock or its calcined form in the removal of phosphate ions as reported by various researchers [98–101]. In their study on the use of calcined rock (Polonite®) in the removal of phosphates from wastewater, Renman et al. [98, 102] noticed also about 18% removal of inorganic forms of nitrogen, which they considered

An experiment of Wąsik et al. [103] investigating the use of calcined rock as a filling of a vertical flow filter operating under variable hydraulic retention time (HRT) identified chemical pro-

filtration of pre-treated domestic sewage through calcined limestone-silicate rock revealed a very high (95%) positive correlation between the removal of phosphates and ammonium

3− and NH<sup>4</sup>

3−/l 89% PO<sup>4</sup>

+

**Sorption capacity, removal efficiency**

(1) 91 ± 11% PO<sup>4</sup>

(2) 87 ± 19% PO<sup>4</sup>

18.2–35.7% P

0.30 g TP/kg (3) 0.28 g TP/kg

40.9 mg P-PO<sup>4</sup>

5.1 mg P-PO<sup>4</sup>

3−/g

3−/g

Mean: (1) 47–97% TP (2) 76–97% TP 3−

3−

removal. A few months long

**References**

3− Cucarella et al. 2009 [98]

2010 [96]

Renmam A, Renmam G.

Jóźwiakowski 2012 [99]

Nilsson et al. 2013 [97]

Jóźwiakowski et al. 2017

Karczmarczyk et al. 2017

[100]

[101]

3− Renmann 2008 [95]

was calcium and phosphorus compounds in the form of hydroxyapatite.

to be losses associated with their evaporation.

Polonite®, 2–5.6 mm Septic tank (domestic

**Type of material, grain** 

Polonite (2–5.6 mm) mixed with 8% peat

Calcined opoka (Polonite), 2–6 mm

Calcined Opoka, 10–50 mm

Polonite® (Bioptech, Hallstavik), 2–5.6 mm

Calcined carbonate– silica rock (opoka) (1) 1–2 mm; (2) 2–5 mm;

Polonite® (Ecofiltration NORDIC), 2–6 mm LECA, 4–10 mm

(3) 5–10 mm

**size**

44 Sewage

cesses, and not biofiltration, as the basic cause of PO<sup>4</sup>

**Wastewater treatment system; phosphates concentration in a influent**

Septic tank + biofilter; 1.9–4.9 mg P-PO<sup>4</sup>

wastewater) + column with Polonite;

wastewater) + column with Polonite

Mechanically treated wastewater, after septic tank in on-site wastewater

1) 4.68 ± 1.88 mg PO<sup>4</sup>

2)5.19 ± 1.86 mg PO<sup>4</sup>

Septic tank (domestic

phosphorus 5.3 ± 2.6 mg/l

(1) mean BZT<sup>7</sup>

8.0 ± 1.7 mg/l; (2) + SBR; mean BZT<sup>7</sup>

treatment system

Septic tank (domestic wastewater) >90% PO<sup>4</sup>

3−/l and

Wetland + opoka; 4–9.1 mgP/l 0.727–1.258 g/kg,

120 mg/l), total phosphorus

20 mg/l, total

**Table 3.** Summary of phosphorus ions sorption capacities for carbonate-silica rocks used in various studies.

Vertical flow filter; domestic wastewater (1) 0.38 g TP/kg; (2)

3−/l

Treatment of domestic sewage in the areas with scattered development remains a serious issue. Discharging ineffectively treated sewage into the environment may cause an increase in the count of pathogenic organisms. In developing countries, where water and sanitation infrastructure is still inadequate, billions of people are exposed to diseases resulting from using unsafe water. The World Health Organization (WHO) estimates that around 1.7 million deaths globally are related to inadequate Water, Sanitation and Hygiene (WaSH) [2, 7]. It is therefore crucial to prevent the spread of gastric and infectious diseases via water. Humans are exposed not only as a result of consumption of contaminated water but also via skin contact during various forms of recreation (e.g. swimming and diving).

[2] Financing Universal Water, Sanitation And Hygiene Under The Sustainable Development Goals, Glaas 2017 Report, UN-Water Global Analysis and Assessment of Sanitation and Drinking-Water, WHO 2017. Available from: http://apps.who.int/iris/bitstream/10665/

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625 47

[3] Federal Register. National primary drinking water regulations; filtration, disinfection; turbidity, *Giardia lamblia*, viruses, legionella, and heterotrophic bacteria: Final rule, U.S.

[4] Federal Register. Drinking Water; National Primary Drinking Water Regulations; Total Coliforms (including Fecal Coliforms and *E. coli*): Final Rule, U.S. Epatologia. 1989;

[5] Karim MR, Manshadi FD, Karpiscak MM, Gerpa CP. The persistence and removal of enteric pathogens in constructed wetlands. Water Research. 2004;**38**(7):1831-1837

[6] Winward G, Avery LM, Stephenson T, Jeffrey P, Le Corre KS, Fewtrell L. Pathogens in urban wastewaters suitable for reuse. Urban Water Journal. 2009;**6**:291-301. DOI: 10.1080/

[7] Naidoo S, Olaniran AO. Treated wastewater effluent as a source of microbial pollution of surface water resources. International Journal of Environmental Research and Public

[8] Frigon D, Biswal BK, Mazza A, Masson L, Gehr R. Biological and physicochemical wastewater treatment processes reduce the prevalence of virulent *Escherichia coli*. Applied and

[10] Langenbach K, Kuschk P, Horn H, Kästner M. Slow sand filtration of secondary clarifier effluent for wastewater reuse. Environmental Science & Technology. 2009;**43**(15):5896-

[11] Langenbach K. Modeling of slow sand filtration for disinfection of secondary clarifier effluent. Water Research. 2010;**44**(1):159-166. DOI: 10.1016/j.watres.2009.09.019

[12] Chmielowski K, Ślizowski R. Defining the optimal range of a filter bed's d(10) replacement diameter in vertical flow sand filters. Environment Protection Engineering. 2008;

[13] Chmielowski K, Ślizowski R. Effect of grain-size distribution of sand on the filtrate quality in vertical-flow filters. Przemysl Chemiczny. 2008;**87**(5):432-434 [in Polish]

[14] Chmielowski K. The Effectiveness of Wastewater Treatment Plants Using a Modified Filter Gravel-sand. Infrastructure and Ecology of Rural Areas. 2013;**1/I**:1-225 [in Polish]

[15] Wąsik E, Chmielowski K. Ammonia and indicator bacteria removal from domestic sewage in a vertical flow filter filled with plastic material. Ecological Engineering. 2017;

[9] Bitton G. Wastewater Microbiology. 4th ed. New York: Wiley-Blackwell; 2011

254999/1/9789241512190-eng.pdf [Accessed: November 11, 2017]

Health. 2014;**11**(1):249-270. DOI: 10.3390/ijerph110100249

Environmental Microbiology. 2013;**79**(3):835

5901. DOI: 10.1021/es900527j

**34**(3):35-42

**106**:378-384

Epatologia. 1989;**54**:27486

15730620802673087

**54**:27544

While one of popular approaches to on-site wastewater treatment system (OWTS) are activated sludge processes such as sequential batch reactors (SBR) due to their cost effectiveness, an inexpensive and simple solution for the treatment of domestic sewage especially in rural areas is septic tank followed by vertical flow filters with different natural media fillings, that is, quartz sand, zeolite and clay. This process route seems to be an economically attractive alternative to sewage treatment for residents without access to a public sewerage system.

Natural materials like zeolite offer the highest mean rate of ammonium nitrogen removal compared with sand or clay media. Sand filters are the most effective in reduction of the indicator bacteria but they have the highest tendency for clogging. It is recommended to undertake research in the field of developing an idea that would protect the sand filter against clogging. Natural materials commonly used as a filling of vertical flow filters may be partly replaced with a plastic filling like PET flakes. Compared with conventional media plastic fillings have high specific surface area and lower tendency to clogging. It is proposed to conduct further research using different materials used alternatively in the multi-layer vertical filters (i.e. sand and plastic media) [108].

Filter media cost is one of the most important factor that affects the cost of vertical flow filters. In areas where the sand are commonly found, its cost is nominal. Alternative filling of filters like clay are moderately cheap. Zeolite is the most expensive filling. Cost of clay, zeolite, calcium-silicate rock is all subject to availability and cost of transport. PET flakes are obtained in the recycling process of commercially available bottles. Detailed cost and long-term costs of plastic media is not available because the PET flakes media is still under study.

#### **Author details**

Ewa Dacewicz\* and Krzysztof Chmielowski Address all correspondence to: ewa.wasik@ur.krakow.pl University of Agriculture, Kraków, Poland

#### **References**

[1] UNICEF Data [Internet]. 2015. Available from: https://data.unicef.org/topic/water-andsanitation/sanitation/ [Accessed: November 11, 2017]

[2] Financing Universal Water, Sanitation And Hygiene Under The Sustainable Development Goals, Glaas 2017 Report, UN-Water Global Analysis and Assessment of Sanitation and Drinking-Water, WHO 2017. Available from: http://apps.who.int/iris/bitstream/10665/ 254999/1/9789241512190-eng.pdf [Accessed: November 11, 2017]

infrastructure is still inadequate, billions of people are exposed to diseases resulting from using unsafe water. The World Health Organization (WHO) estimates that around 1.7 million deaths globally are related to inadequate Water, Sanitation and Hygiene (WaSH) [2, 7]. It is therefore crucial to prevent the spread of gastric and infectious diseases via water. Humans are exposed not only as a result of consumption of contaminated water but also via skin con-

While one of popular approaches to on-site wastewater treatment system (OWTS) are activated sludge processes such as sequential batch reactors (SBR) due to their cost effectiveness, an inexpensive and simple solution for the treatment of domestic sewage especially in rural areas is septic tank followed by vertical flow filters with different natural media fillings, that is, quartz sand, zeolite and clay. This process route seems to be an economically attractive alternative to sewage treatment for residents without access to a public sewerage system.

Natural materials like zeolite offer the highest mean rate of ammonium nitrogen removal compared with sand or clay media. Sand filters are the most effective in reduction of the indicator bacteria but they have the highest tendency for clogging. It is recommended to undertake research in the field of developing an idea that would protect the sand filter against clogging. Natural materials commonly used as a filling of vertical flow filters may be partly replaced with a plastic filling like PET flakes. Compared with conventional media plastic fillings have high specific surface area and lower tendency to clogging. It is proposed to conduct further research using different materials used alternatively in the multi-layer vertical filters

Filter media cost is one of the most important factor that affects the cost of vertical flow filters. In areas where the sand are commonly found, its cost is nominal. Alternative filling of filters like clay are moderately cheap. Zeolite is the most expensive filling. Cost of clay, zeolite, calcium-silicate rock is all subject to availability and cost of transport. PET flakes are obtained in the recycling process of commercially available bottles. Detailed cost and long-term costs of

[1] UNICEF Data [Internet]. 2015. Available from: https://data.unicef.org/topic/water-and-

plastic media is not available because the PET flakes media is still under study.

tact during various forms of recreation (e.g. swimming and diving).

(i.e. sand and plastic media) [108].

Ewa Dacewicz\* and Krzysztof Chmielowski

University of Agriculture, Kraków, Poland

Address all correspondence to: ewa.wasik@ur.krakow.pl

sanitation/sanitation/ [Accessed: November 11, 2017]

**Author details**

46 Sewage

**References**


[16] Wąsik E, Chmielowski K. Effectiveness of indicator bacteria removal in vertical flow filters filled with natural materials. Environment Protection Engineering. 2017 (in press)

during a one-year pilot study in a cold temperate climate. Journal of Environmental

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625 49

[29] Pfannes KR, Langenbach KM, Pilloni G, Stührmann T, Euringer K, Lueders T, Neu TR, Müller JA, Kästner M, Meckenstock RU. Selective elimination of bacterial faecal indicators in the Schmutzdecke of slow sand filtration columns. Applied Microbiology and

[30] Seeger EM, Braeckevelt M, Reiche N, Müller JA, Kästner M. Removal of pathogen indicators from secondary effluent using slow sand filtration: Optimization approaches.

[31] Bellamy WD, Hendricks DW, Logsdon GS. Slow sand filtration: Influences of selected process variables. Journal of American Water Well Association. 1985;**77**:62-66

[32] Jenkins MW, Tiwari SK, Darby J. Bacterial, viral and turbidity removal by intermittent slow sand filtration for household use in developing countries: Experimental investigation and modeling. Water Research. 2011;**45**:6227-6239. DOI: 10.1016/j.watres.2011.09.022

[33] Aronino R, Dlugy C, Arkhangelsky E, Shandalov S, Oron G, Brenner A, Gitis V. Removal of viruses from surface water and secondary effluents by sand filtration. Water Research.

[34] Rouquerol J, Avnir D, Fairbridge C, Everett DH, Haynes JH, Pernicone N, Ramsay JDF, Sing KSW, Unger KK. IUPAC, Recommendations for the characterization of porous sol-

[35] Papciak D, Kaleta J, Puszkarewicz A. Removal of ammonia nitrogen from groundwater on Chalcedony deposits in two-stage Biofiltration process. Annual Set The Environment

[36] Kalenik M, Wancerz M. Research of sewage treatment in mean sand with assist layer with chalcedonite - laboratory scale. Infrastructure and Ecology of Rural Areas. 2013;**3/I**:

[37] Chandra S, Berntsson L. Lightweight Aggregate Concrete: Science, Technology and

[38] Stevik TK, Kari A, Ausland G, Hanssen JF. Retention and removal of pathogenic bacteria in wastewater percolating through porous media: A review. Water Research. 2004;

[39] Masłoń A, Tomaszek JA. Keramzyt w systemach oczyszczania ścieków [Use of the keramsite in wastewater treatment]. Zeszyty Naukowe PR Nr 271. 2010;**57**(3/10):85-98 [40] Lekang OI, Kleppe H. Efficiency of nitrification in trickling filters using different filter

[41] Jucherski A, Nastawny M. Effectiveness of removing nitrogen compounds from domestic sewage in trickling leca beds of different hydraulic and organic substrate loads.

Applications. Norwich, New York, USA: William Andrew Publishing; 2002

ids. Pure and Applied Chemistry. 1994;**66**(8):1739-1758

media. Aquacultural Engineering. 2000;**21**(3):181-199

Problems of Agricultural Engineering. 2012;**78**:171-181

Protection. 2013;**15**:1352-1366 [in Polish]

Biotechnology. 2015;**99**(23):10323-10332. DOI: 10.1007/s00253-015-6882-9

Ecological Engineering. 2016;**95**:635-644. DOI: 10.1016/j.ecoleng.2016.06.068

Management. 2014;**133**:206-213

2009;**43**:87-96

163-173 [in Polish]

**38**:1355-1367


during a one-year pilot study in a cold temperate climate. Journal of Environmental Management. 2014;**133**:206-213

[29] Pfannes KR, Langenbach KM, Pilloni G, Stührmann T, Euringer K, Lueders T, Neu TR, Müller JA, Kästner M, Meckenstock RU. Selective elimination of bacterial faecal indicators in the Schmutzdecke of slow sand filtration columns. Applied Microbiology and Biotechnology. 2015;**99**(23):10323-10332. DOI: 10.1007/s00253-015-6882-9

[16] Wąsik E, Chmielowski K. Effectiveness of indicator bacteria removal in vertical flow filters filled with natural materials. Environment Protection Engineering. 2017 (in press)

[17] Elliott M, Stauber CE, FA DG, Fabiszewski de Aceituno A, Sobsey MD. Investigation of E. coli and virus reductions using replicate, bench-scale biosand filter columns and two filter media. International Journal of Environmental Research and Public Health.

[18] Unger M, Collins MR. Assessing the role of the schmutzdecke in slow sand and riverbank filtration. In: Gimbel R, Graham NJD, Collins MR, editors. Recent Progress in Slow

[19] Unger M, Collins MR. Assessing the role of the schmutzdecke in slow sand and riverbank filtration. In: Proceedings, AWWA Annual Conference 2006; San Antonio, TX [20] Zhu IX, Bates BJ. Conventional media filtration with biological activities. In: Elshorbagy W, Chowdhury RK, editors. Water Treatment. Rijeka, Croatia: InTech; January 1, 2013.

[21] Zhu IX, Getting T, Bruce D. Review of biologically active filters in drinking water appli-

[22] White KD. Performance and economic feasibility of alternative on-site wastewater treatment and disposal options: Peat biofilters, constructed wetlands, and intermittent sand filters. In: Proceedings of the 68th Annual Conference and Exposition, Water Environ-

[23] Asenizacja indywidualna [Individual sanitation]. Zeszyty Techniczne nr 1 Francuskiego Ministerstwa Ochrony Środowiska. Warszawa: Wyd. Biuro Współpracy Polsko-Fran-

[24] Metcalf & Eddy. Wastewater Engineering, Treatment, Disposal, Reuse. 3rd ed. New York:

[25] Wąsik E, Kaczor G, Bugajski P. Impact of selected thicknesses of vertical sand filters on the quality of treated domestic wastewater. Annual Set The Environment Protection.

[26] Yettefti IK, Aboussabiq FA, Etahiri S, Malamis D, Assobhei O. Slow sand filtration of effluent from an anaerobic denitrifying reactor for tertiary treatment: A comparable study, using three Moroccan sands. Carpathian Journal of Earth and Environmental

[27] Aloo BN, Mulei J, Mwamburi AL. Slow sand filtration of secondary sewage effluent: Effect of sand bed depth on filter performance. The International Journal of Innovative Research in Science, Engineering and Technology. 2014;**3**(8):15090-15099. DOI: 10.15680/

[28] Kauppinen A, Martikainen K, Matikka V, Veijalainen A-M, Pitkänen T, Heinonen-Tanski H, Miettinen IT. Sand filters for removal of microbes and nutrients from wastewater

Sand and Alternative Biofiltration Processes. London: IWA Publishers; 2006

2015;**12**:10276-10299. DOI: 10.3390/ijerph120910276

pp. 137-166. DOI: 10.5772/50481

48 Sewage

McGraw-Hill; 1991

2017 (submitted) [in Polish]

Sciences. 2013;**8**(3):207-218

IJIRSET.2014.0308006

cations. Journal AWWA. 2010;**102**(12):67-77

ment Federation; 1995; Miami, FL, USA. 1995. pp. 129-138

cuskiej w Dziedzinie Ochrony Środowiska; 1992 [in Polish]


[42] Faghihian H, Bowman RS. Adsorption of chromate by clinoptilolite exchanged with various metal cations. Water Research. 2005;**39**:1099-1104

[56] Wang S, Peng Y. Natural zeolites as effective adsorbents in water and wastewater treat-

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625

[57] Widiastuti N, Wu H, Ang HM, Zhang D. The potential application of natural zeolite for

[58] Widiastuti N, Wu H, Ang HM, Zhang D. Removal of ammonium from greywater using

[59] Juan R, Hernández S, Andrés JM, Ruiz C. Ion exchange uptake of ammonium in wastewater from a sewage treatment plant by zeolitic materials from fly ash. Journal of

[60] Zabochnicka-Swiatek M, Malinska K. Removal of ammonia by clinoptilolite. Global

[61] Wang X, Lü S, Gao C, Xu X, Zhang X, Bai X, Liu M, Wu L. Highly efficient adsorption of ammonium onto palygorskite nanocomposite and evaluation of its recovery as a multifunctional slow-release fertilizer. Chemical Engineering Journal. 2014;**252**:404-414

[62] Ferronato C, Vianello G, Antisari LV. Adsorption of pathogenic microorganisms, NH<sup>4</sup>

[63] Wiśniowska E, Karwowska B, Sperczyńska E. Interwencyjne wykorzystanie zeolitów w oczyszczaniu ścieków [Emergency use of zeolites in wastewater treatment]. Zeszyty

[64] Turan M. Application of nanoporous zeolites for the removal of ammonium from wastewaters: A review. In: Ünlü H, NJM H, Dabrowski J, editors. Low-Dimensional and Nanostructured Materials and Devices. Switzerland: Springer International Publishing;

[65] Das P, Prasad B, Singh KKK. Applicability of Zeolite Based Systems for Ammonia Removal and Recovery From Wastewater. Water Environment Research. 2017:840-845

[66] Gupta VK, Sadegh H, Yari M, Shahryari Ghoshekandi R, Maazinejad B, Chahardori M. Removal of ammonium ions from wastewater a short review in development of efficient methods. Global Journal of Environmental Science and Management. 2015;

[67] Kalló D. Wastewater purification in Hungary using natural zeolites. Reviews in

[68] El-Shafey O, Fathy NA, El-Nabarawy T. Sorption of ammonium ions onto natural and modified Egyptian kaolinites: Kinetic and equilibrium studies. Advances in Physical

[69] Wąsik E. Selective and porous materials of filter beds and removal of biogenic compounds and pathogenic bacteria from domestic sewage. Acta Scientiarum Polonorum-

and heavy metals from wastewater by clinoptilolite using bed laminar flow. 2015. DOI:

+

51

Hazardous Materials. 2009;**161**(2-3):781-786. DOI: 10.1016/j.jhazmat.2008.04.025

ment. Chemical Engineering Journal. 2010;**156**:11-24

greywater treatment. Desalination. 2008;**218**:271-280

Naukowe UZ, Inżynieria Środowiska. 2015;**40**:56-63

Mineralogy and Geochemistry. 2001;**45**:519-550

Formatio Circumiectus. 2017 (submitted) [in Polish]

Chemistry. 2014;**2014**:1-12. ID: 935854

natural zeolite. Desalination. 2011;**277**:15-23

NEST Journal. 2010;**12**(3):256-261

10.1180/claymin.2015.050.1.01

2016. pp. 477-504

**1**(2):149-158


[56] Wang S, Peng Y. Natural zeolites as effective adsorbents in water and wastewater treatment. Chemical Engineering Journal. 2010;**156**:11-24

[42] Faghihian H, Bowman RS. Adsorption of chromate by clinoptilolite exchanged with

[43] Englert AH, Rubio J. Characterization and environmental application of a Chilean natu-

[44] Gottardi G, Galli E. Natural Zeolites. Berlin Heidelberg New York, Tokyo: Springer-

[45] Kithome M, Paul JW, Lavkulich LM, Bomke AA. Effect of pH on ammonium adsorption by natural zeolite clinoptilolite. Communications in Soil Science and Plant Analysis.

[46] International Zeolite Association, Database of Zeolite Structures. Available from: http://

[47] Abd El-Hady HM, Grünwald A, Vlčková K, Zeithammerová J. Clinoptilolite in Drinking Water Treatment for Ammonia Removal. Acta Polytechnica. 2001;**41**(1):41-45

[48] Li M, Zhu X, Zhu F, Ren G, Cao G, Song L. Application of modified zeolite for ammonium removal from drinking water. Desalination. 2011;**271**(1-3):295-300. DOI: 10.1016/j.

[49] Margeta K, Zabukovec Logar N, Šiljeg M, Farkaš A. Natural zeolites in water treatment – How effective is their use. In: Elshorbagy W, Chowdhury RK, editors. Water Treatment.

[50] Mažeikiene A, Valentukevičiene M, Rimeika M, Matuzevičius AB, Dauknys R. Removal of nitrates and ammonium ions from water using natural sorbent zeolite (clinoptilolite). Journal of Environmental Engineering and Landscape Management. 2008;**16**(1):38-44.

[51] Shoumkova A. Zeolites for water and wastewater treatment: An overview. Research Bulletin of the Australian Institute of High Energetic Materials, Special Issue on Global

[52] Bedelean H, Măicăneanu A, Burcă S, Stanca M. Romanian zeolitic volcanic tuffs and bentonites used to remove ammonium ions from wastewaters. Hellenic. Journal of Geo-

[53] Deng Q. Ammonia removal and recovery from wastewater using natural zeolite: An integrated system for regeneration by air stripping followed ion exchange [thesis].

[54] Sprynskyy M, Lebedynets M, Terzyk AP, Kowalczyk P, Namieśnik J, Buszewski B. Ammonium sorption from aqueous solutions by the natural zeolite transcarpathian clinoptilolite studied under dynamic conditions. Journal of Colloid and Interface

[55] Syafalni S, Abustan I, Dahlan I, Wah CK, Umar G. Treatment of dye wastewater using granular activated carbon and zeolite filter. Modern Applied Science. 2012;**6**(2). DOI:

ral zeolite. International Journal of Mineral Processing. 2005;**75**(1-2):21-29

various metal cations. Water Research. 2005;**39**:1099-1104

www.iza-structure.org/databases [Accessed: October 10, 2017]

Rijeka, Croatia: InTech; 2013. pp. 81-112. DOI: 10.5772/50738

Waterloo, Ontario, Canada: University of Waterloo; 2014

DOI: 10.3846/1648-6897.2008.16.38-44

Fresh Water Shortage. 2011;**2**:10-70

sciences. 2010;**45**:23-32

Science. 2005;**284**:408-415

10.5539/mas.v6n2p37

Verlang; 1995. pp. 257-284

50 Sewage

1999;**30**(9-10):1417-1430

desal.2010.12.047


[70] Chen X, Hu S, Shen C, Dou C, Shi J, Chen Y. Interaction of *Pseudomonas putida* with clays and ability of the composite to immobilize copper and zinc from solution. Bioresource Technology. 2009;**100**:330-337

[84] EPA 832-F-00-014, September 2000, Wastewater Technology Fact Sheet, Trickling Filters [85] McQuarrie JP, Boltz JP. Moving bed biofilm reactor technology: Process applications,

The Importance of Media in Wastewater Treatment http://dx.doi.org/10.5772/intechopen.75625 53

[86] ADF Health Manual, 2013. Vol. 20, Part 8, Chapter 2. Available from: http://ebookpoint. us/scribd/adf-health-manual-vol-20-part8-chp2-192004268 [Accessed: October 10, 2017]

[87] EPA 832-F-00-015, September 2000, Wastewater Technology Fact Sheet, Trickling Filter

[88] Galbraith JM, Zipper CE, Reneau RB Jr. On-site sewage treatment alternatives. Virginia Cooperative Extension, Virginia Polytechnic Institute and State University. 2015: 448-407

[89] Harwanto D, Oh SY, Jo JY. Comparison of the nitrification efficiencies of three Biofilter Media in a Freshwater System. Fisheries and Aquatic Sciences. 2011;**14**(4):363-369

[90] Nijhof M. Bacterial stratification and hydraulic loading effects in a plug-flow model for nitrifying trickling filters applied in recirculating fish culture systems. Aquaculture.

[91] Moulick S, Tanveer M, Mukherjee CK. Evaluation of nitrification performance of a trickling filter with nylon pot scrubber as media. International Journal of Science and Nature.

[92] Kishimoto N, Ohara T, Hinobayashi J, Hashimoto T. Roughness and temperature effects on the filter media of a trickling filter for nitrification. Environmental Technology.

[93] Stephenson T, Reid E, Avery LM, Jefferson B. Media surface properties and the development of nitrifying biofilms in mixed cultures for wastewater treatment. Process Safety

[94] Brogowski Z, Renman G. Characterization of Opoka as a basis for its use in wastewater

[95] Renman A. On-site wastewaters treatment – polonite and other filter materials for removal of metals, nitrogen and phosphorus [thesis]. Stockholm: KTH Royal Institute

[96] Renman A, Renman G. Long-term phosphate removal by the calcium-silicate material

[97] Nilsson C, Renman G, Westholm LJ, Renman A, Drizo A. Effect of organic load on phosphorus and bacteria removal from wastewater using alkaline filter materials. Water

[98] Cucarella V, Renman G. Phosphorus sorption capacity of filter materials used for on-site wastewater treatment determined in batch experiments–a comparative study. Journal of

Polonite in wastewater filtration systems. Chemosphere. 2010;**79**:659-664

Environmental Quality. 2009;**38**(2):381-392. DOI: 10.2134/jeq2008.0192

treatment. Polish Journal of Environmental Studies. 2004;**13**(1):15-20

2014;**35**(12):1549-1555. DOI: 10.1080/09593330.2013.873484

and Environmental Protection. 2013;**91**(4):321-324

design, and performance. Water Environment Research. 2011;**83**(6):560-575

Nitrification

1995;**134**(1-2):49-64

2011;**2**(3):515-518

of Technology; 2008

Research. 2013;**47**(16):6289-6297


[84] EPA 832-F-00-014, September 2000, Wastewater Technology Fact Sheet, Trickling Filters

[70] Chen X, Hu S, Shen C, Dou C, Shi J, Chen Y. Interaction of *Pseudomonas putida* with clays and ability of the composite to immobilize copper and zinc from solution. Bioresource

[71] Park SJ, Sool H, Yoon T. The evaluation of enhanced nitrification by immobilized biofilm

[72] Stotzky G. Mechanisms of adhesion to clays, with reference to soil systems. In: Savage DC, Fletcher M, editors. Bacterial Adhesion. Boston, Massachusetts, USA: Springer;

[73] Lukasik J, Cheng YF, Lu F, Tamplin M, Farrah SR. Removal of microorganisms from water by columns containing sand coated with ferric and aluminum hydroxides. Water

[74] Truesdail S, Lukasik J, Farra S, Shah D, Dickinson R. Analysis of bacterial deposition on metal (Hydr)oxide-coated sand filter media. Journal of Colloid and Interface Science.

[75] Foppen JW, Liem Y, Schijven J. Effect of humic acid on the attachment of Escherichia coli

[76] Karadag D, Tok S, Akgul E, Turan M, Ozturk M, Demir A. Ammonium removal from sanitary landfill leachate using natural Gordes clinoptilolite. Journal of Hazardous

[77] Kanawade SM. Removal of ammonium and suspended solids from effluent of domestic wastewater plant. International Journal of Applied Research. 2015;**1**(10):194-200

[78] Kalenik M. Skuteczność oczyszczania ścieków w gruncie piaszczystym z warstwą naturalnego klinoptylolitu [Efficiency of wastewater treatment in sandy soil with a layer of

[79] Syafalni S, Abustan I, Dahlan I, Kok Wah C, Umar G. Treatment of dye wastewater using granular activated carbon and zeolite filter. Modern Applied Science. 2012;**6**(2):37-51.

[80] Wąsik E, Chmielowski K. The effectiveness of domestic wastewater treatment in sand filters vertical flow of granular activated carbon addition. Infrastructure and Ecology of

[81] Wąsik E, Chmielowski K. Effect of activated carbon layer at sand-carbon filters vertical

[82] Çeçen F, Aktaş Ö. Activated Carbon for Water and Wastewater Treatment: Integration of Adsorption and Biological Treatment. 1st ed. KGaA: WILEY-VCH Verlag GmbH &

[83] Chaudhary DS, Vigneswaran S, Ngo HH, Shim WG, Moon H. Biofilter in Water and Wastewater Treatment, Review. Korean Journal of Chemical Engineering. 2003;**20**(6):

natural clinoptilolite]. Ochrona Środowiska. 2014;**36**(3):43-48 [In Polish]

flow in domestic wastewater treatment. NPT. 2014;**8**(4):1-11 [in Polish]

in columns of goethite-coated sand. Water Research. 2008;**42**:211-219

on a clinoptilolite carrier. Bioresource Technology. 2002;**82**:183-189

Technology. 2009;**100**:330-337

1985. pp. 195-253

52 Sewage

1998;**203**:369-378

Research. 1999;**33**:769-777

Materials. 2008;**153**:60-66

DOI: 10.5539/mas.v6n2p37

Co.; 2011

1054-1065

Rural Areas. 2013;**3/I**:7-17 [in Polish]


[99] Jóźwiakowski K. Badania skuteczności oczyszczania ścieków w wybranych systemach gruntowo-roślinnych. Infrastruktura i ekologia terenów wiejskich. 2012;**1**:1-232 [in Polish]

**Chapter 4**

**Provisional chapter**

**A Review: Assessment of Trace Metals in Municipal**

**A Review: Assessment of Trace Metals in Municipal** 

Trace metals including nanosilver in our aquatic environment are on the increase in part due to discharge from municipal sewage and indirectly from leaching from abandoned mine tailings and from sludge spread on farmland. The presence of the trace metals will likely impact negatively on the aquatic environment in excess of background levels. This review reports on the concentration of trace metals in municipal sewage in Limpopo province and the impact on fish and human health. Human health risks associated with the consumption of contaminated fish are discussed. The presence of silver is also highlighted and the remedial actions that are available in reducing the health risks including positive outcomes are discussed. The source of silver may be from the use of silver nanoproducts. There is a need for a paradigm shift of zero effluent discharge and start with harvesting of

metals from the sewage effluent and sludge in order to protect the environment. **Keywords:** trace metals, bioaccumulation, biomagnification, fish consumption,

Trace metals in our aquatic environment are on the increase due to discharge from municipal sewage, active and abandoned mine tailings, and non-point pollution sources. Here, the trace metals may originate from metal fabrication industry [1], road runoff stormwater drains that are connected to municipal sewage plants [2–4], tannery industry [5], and from domestic households where zinc/copper scrubbers are used [6]. Trace metals have been known to originate from active and abandoned mine tailings, and these trace metals enter the aquatic

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.76565

**Sewage and Sludge: A Case Study of Limpopo**

**Sewage and Sludge: A Case Study of Limpopo** 

**Province, South Africa**

**Province, South Africa**

Kudakwashe K. Shamuyarira and

http://dx.doi.org/10.5772/intechopen.76565

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Kudakwashe K. Shamuyarira and Jabulani R. Gumbo

Jabulani R. Gumbo

**Abstract**

human health

**1. Introduction**


#### **A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study of Limpopo Province, South Africa A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study of Limpopo Province, South Africa**

DOI: 10.5772/intechopen.76565

Kudakwashe K. Shamuyarira and Jabulani R. Gumbo Kudakwashe K. Shamuyarira and Jabulani R. Gumbo Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.76565

#### **Abstract**

[99] Jóźwiakowski K. Badania skuteczności oczyszczania ścieków w wybranych systemach gruntowo-roślinnych. Infrastruktura i ekologia terenów wiejskich. 2012;**1**:1-232 [in

[100] Jóźwiakowski K, Gajewska M, Pytka A, Marzec M, Gizińska-Górna M, Jucherski A, Walczowski A, Nastawny M, Kamińska A, Baran S. Influence of the particle size of carbonate-siliceous rock on the efficiency of phosphorous removal from domestic waste-

[101] Karczmarczyk A, Woja K, Bliska P, Baryła A, Bus A. The efficiency of filtration materials (Polonite® and LECA®) supporting phosphorus removal in on-site treatment systems with wastewater infiltration. Infrastructure and Ecology of Rural Areas. 2017;

[102] Renmam A, Hylander LD, Renman G. Transformation and removal of nitrogen in reactive bed filter materials designed for on-site wastewater treatment. Ecological

[103] Wąsik E, Bugajski P, Chmielowski K, Nowak A, Mazur R. Crystallization of struvite and hydroxyapatite during removal of biogenic compounds on the filter bed. Przemysl

[104] Robinson H. On the formation of struvite by micro-organisms. Proceedings of the

[105] Zhang T, Jiang R, Deng Y. Phosphorus recovery by struvite crystallization from livestock wastewater and reuse as fertilizer: A review. In: Farooq R, Ahmad Z, editors. Physico-Chemical Wastewater Treatment and Resource Recovery. Rijeka, Croatia:

[106] Cucarella V, Mazurek R, Zaleski T, Kopeć M, Renman G. Effect of Polonite used for phosphorus removal from wastewater on soil properties and fertility of a mountain

[107] de-Bashana LE, Bashan Y. Recent advances in removing phosphorus from wastewater and its future use as fertilizer (1997-2003). Water Research. 2004;**38**:4222-4246

[108] Dacewicz E. Vertical flow filters filled with PET flakes or PU foam. 2018 [unpublished

Chemiczny. 2017;**96**(8):1739-1743. DOI: 10.15199/62.2017.8.27

meadow. Environmental Pollution. 2009;**157**(7):2147-2152

Cambridge Philosophical Society. 1889;**6**:360-362

water. Ecological Engineering. 2017;**98**:290-296

Polish]

54 Sewage

**IV**(1):1401-1413

Engineering. 2008;**34**(3):207-214

InTech; 2017. DOI: 10.5772/65692

work in Polish]

Trace metals including nanosilver in our aquatic environment are on the increase in part due to discharge from municipal sewage and indirectly from leaching from abandoned mine tailings and from sludge spread on farmland. The presence of the trace metals will likely impact negatively on the aquatic environment in excess of background levels. This review reports on the concentration of trace metals in municipal sewage in Limpopo province and the impact on fish and human health. Human health risks associated with the consumption of contaminated fish are discussed. The presence of silver is also highlighted and the remedial actions that are available in reducing the health risks including positive outcomes are discussed. The source of silver may be from the use of silver nanoproducts. There is a need for a paradigm shift of zero effluent discharge and start with harvesting of metals from the sewage effluent and sludge in order to protect the environment.

**Keywords:** trace metals, bioaccumulation, biomagnification, fish consumption, human health

#### **1. Introduction**

Trace metals in our aquatic environment are on the increase due to discharge from municipal sewage, active and abandoned mine tailings, and non-point pollution sources. Here, the trace metals may originate from metal fabrication industry [1], road runoff stormwater drains that are connected to municipal sewage plants [2–4], tannery industry [5], and from domestic households where zinc/copper scrubbers are used [6]. Trace metals have been known to originate from active and abandoned mine tailings, and these trace metals enter the aquatic

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

environment during rainy events [7–9] or windy events [10]. Some of the non-point pollutions are as follows: trace metals also leaching from sewage sludge spread on farmland [11] and discharge of bath water to the terrestrial environment where there is leaching to the aquatic environment. In rural areas of developing countries, there is no municipal sewer system, and the communities practicing disposal of wastewater to the terrestrial environment is common. Silver and silver nanoparticles have been found in the terrestrial environment and in municipal sewage as a result of the human use of silver deodorant products and silver nanoproducts [12, 13]. The sewage sludge disposal and the fate of silver nanoparticles and trace metals and their possible effects to the environment are reviewed. The presence of the trace metals will likely impact negatively on the aquatic environment in excess of background levels (**Figure 1**).

impoundments and rivers inside the Kruger National Park and other nature conservation areas directly and indirectly linked to metal pollution [15]. In the 2013 Green Drop assessment by the Department of Water Affairs (DWA), Limpopo province was forth from last on assessment performance [16]. Lastly, the drinking water sources for major urban areas such as Polokwane rely on groundwater for additional water supply sources which are recharge with wastewater effluent [18], and rural areas rely on surface water and groundwater sources for human consumption. The review investigates the studies that have occurred looking at the discharge of sewage effluent in terms of metal content and the environmental impact of these metals on aquatic fauna and flora. The study also investigates the metal content of trace metals of the municipal sewage sludge in the selected sewage plants in the study period.

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

http://dx.doi.org/10.5772/intechopen.76565

57

The review is based on articles between 2012 and 2018. The keywords were sewage, wastewa-

The major river systems in the Limpopo province are the Nyl River, the Sand River, the Nzhelele River, and the Luvuvhu River; Oliphant River and these are some of the tributaries of the Limpopo River in South Africa. The municipal sewage plants are located near these major rivers or their tributaries. The Nyl River system is fed by the Klein and Groot Nyl Rivers and has a floodplain and a Ramsar wetland. The likely source of metal pollution is sewage plants from Modimolle and Mookgophong that discharge their effluent into the Nyl River [17]. The Sand River originates from Drakensberg Mountains and flows past Polokwane city and flows northward, past farming areas, formal and informal residential areas, mines, nature reserves, and joins the Limpopo River [18]. The Seshego township sewage plant discharges its effluent into the Blood River. The Polokwane sewage plant serving the Polokwane city discharges its effluent into the Sand River. Thus, the source of metal pollution of the Sand River is effluent discharged from sewage plants. The Luvuvhu River originates in Soutpansberg Mountains, flows into Albasini and Nandoni dams, and joins the Limpopo River. There are formal and informal residential and towns, subsistence and commercial farming that are taking place along the Luvuvhu River. Thohoyandou town is the major urban settlement, and the Thohoyandou sewage plant discharges its effluent into Mvudi River [19]. Other sewage plants are located in Waterval Township and urban area of Elim and these discharge their effluent into the Mudzwiriti and Doringspruit Rivers which flow into the Luvuvhu River and Albasini dam, respectively [20].

The Nzhelele River originates from Soutpansberg Mountains, meanders past rural communities, and flows past Nzhelele dam northwards into the Limpopo River. The sources of metal pollution are Siloam and Makhado oxidation ponds which discharge their effluent into the Nzhelele River [21, 22]. The area is characterized by urban settlements of Biaba and residential houses, some with pit latrines, subsistence and commercial farming and nature reserves. On the Oliphant River catchment, there are a number of municipal sewage plants

ter, Limpopo, crocodile, metals, effluent, fish, risk assessment, and human health.

**2. Methodology**

**3. Characteristics of the study area**

However, the municipal sewage sludge and sewage wastewater are also a source of trace metals that are essential for plant and human growth. The municipal sewage sludge is applied on farmland in order to improve land fertility, and irrigation of crops/vegetables with sewage wastewater is also beneficial. We choose Limpopo province for the following reasons. The Limpopo province is the fifth gross domestic product (GDP), based on 2010 figures, of South Africa based on commercial agriculture, mining, manufacturing, goods and services, and tourism with world renowned Kruger National Park [14, 15]. Secondly, the Limpopo province has experienced a surge in crocodiles and fish mortalities in freshwater

**Figure 1.** Schematic diagram illustrating the movement of trace metals toward freshwater environment.

impoundments and rivers inside the Kruger National Park and other nature conservation areas directly and indirectly linked to metal pollution [15]. In the 2013 Green Drop assessment by the Department of Water Affairs (DWA), Limpopo province was forth from last on assessment performance [16]. Lastly, the drinking water sources for major urban areas such as Polokwane rely on groundwater for additional water supply sources which are recharge with wastewater effluent [18], and rural areas rely on surface water and groundwater sources for human consumption. The review investigates the studies that have occurred looking at the discharge of sewage effluent in terms of metal content and the environmental impact of these metals on aquatic fauna and flora. The study also investigates the metal content of trace metals of the municipal sewage sludge in the selected sewage plants in the study period.

#### **2. Methodology**

environment during rainy events [7–9] or windy events [10]. Some of the non-point pollutions are as follows: trace metals also leaching from sewage sludge spread on farmland [11] and discharge of bath water to the terrestrial environment where there is leaching to the aquatic environment. In rural areas of developing countries, there is no municipal sewer system, and the communities practicing disposal of wastewater to the terrestrial environment is common. Silver and silver nanoparticles have been found in the terrestrial environment and in municipal sewage as a result of the human use of silver deodorant products and silver nanoproducts [12, 13]. The sewage sludge disposal and the fate of silver nanoparticles and trace metals and their possible effects to the environment are reviewed. The presence of the trace metals will likely impact negatively on the aquatic environment in excess of background levels (**Figure 1**). However, the municipal sewage sludge and sewage wastewater are also a source of trace metals that are essential for plant and human growth. The municipal sewage sludge is applied on farmland in order to improve land fertility, and irrigation of crops/vegetables with sewage wastewater is also beneficial. We choose Limpopo province for the following reasons. The Limpopo province is the fifth gross domestic product (GDP), based on 2010 figures, of South Africa based on commercial agriculture, mining, manufacturing, goods and services, and tourism with world renowned Kruger National Park [14, 15]. Secondly, the Limpopo province has experienced a surge in crocodiles and fish mortalities in freshwater

56 Sewage

**Figure 1.** Schematic diagram illustrating the movement of trace metals toward freshwater environment.

The review is based on articles between 2012 and 2018. The keywords were sewage, wastewater, Limpopo, crocodile, metals, effluent, fish, risk assessment, and human health.

#### **3. Characteristics of the study area**

The major river systems in the Limpopo province are the Nyl River, the Sand River, the Nzhelele River, and the Luvuvhu River; Oliphant River and these are some of the tributaries of the Limpopo River in South Africa. The municipal sewage plants are located near these major rivers or their tributaries. The Nyl River system is fed by the Klein and Groot Nyl Rivers and has a floodplain and a Ramsar wetland. The likely source of metal pollution is sewage plants from Modimolle and Mookgophong that discharge their effluent into the Nyl River [17]. The Sand River originates from Drakensberg Mountains and flows past Polokwane city and flows northward, past farming areas, formal and informal residential areas, mines, nature reserves, and joins the Limpopo River [18]. The Seshego township sewage plant discharges its effluent into the Blood River. The Polokwane sewage plant serving the Polokwane city discharges its effluent into the Sand River. Thus, the source of metal pollution of the Sand River is effluent discharged from sewage plants. The Luvuvhu River originates in Soutpansberg Mountains, flows into Albasini and Nandoni dams, and joins the Limpopo River. There are formal and informal residential and towns, subsistence and commercial farming that are taking place along the Luvuvhu River. Thohoyandou town is the major urban settlement, and the Thohoyandou sewage plant discharges its effluent into Mvudi River [19]. Other sewage plants are located in Waterval Township and urban area of Elim and these discharge their effluent into the Mudzwiriti and Doringspruit Rivers which flow into the Luvuvhu River and Albasini dam, respectively [20].

The Nzhelele River originates from Soutpansberg Mountains, meanders past rural communities, and flows past Nzhelele dam northwards into the Limpopo River. The sources of metal pollution are Siloam and Makhado oxidation ponds which discharge their effluent into the Nzhelele River [21, 22]. The area is characterized by urban settlements of Biaba and residential houses, some with pit latrines, subsistence and commercial farming and nature reserves. On the Oliphant River catchment, there are a number of municipal sewage plants that discharge effluent either directly into the Oliphant River [15] or via some of tributaries such as the Elands River [23] and Ga-Selati River [24]. The Oliphant River is the most polluted river in South Africa and this is mainly due to mining activities, especially acid mine drainage, commercial and subsistence farming, and formal and informal residential discharges from municipal sewage plants [15, 25].

#### **4. Results and discussion**

#### **4.1. Evidence of trace metal in freshwater environment**

South Africa is a dry country, and rivers and streams flow during the rainy seasons. However, the location of sewage plants near streams and rivers means that the effluent is discharged into the streams and rivers and this contributes to base flow even during periods of no rainfall [20, 25]. The inflow from sewage effluents contributes to the build-up of trace metals in the freshwater environment. There are a number of studies that have shown the presence of trace metals on the freshwater environment (rivers and impoundments) in the Limpopo province of South Africa [15, 18–21, 24, 26–28]. In some cases, the trace metals are in excess of background levels, and the trace metals may become toxic to aquatic life and contaminate drinking water sources (**Table 1**). The pH values in the study sites were generally near the neutral, and therefore there was no contribution of metals due to the dissolution of bedrock or mining activities.

#### *4.1.1. Aluminum (Al)*

The study by Greenfield et al. [17] on the Nyl River system showed that the Al levels are higher than the target water-quality range (TWQR) of 10 μg/l during the study period. The presence of Al was attributed in part due to discharge of sewage effluent into the Groot Nyl River, a subtributary of the Nyl River, and rainfall-induced erosion of local bedrock. The study by Edokpayi et al. [19, 21, 24] showed variation in the Al level in the Ga-Selati, Nzhelele, Mvudi, and Dzindi Rivers in excess of the target water-quality range. The high level of Al may be attributed to the Thohoyandou sewage plant which discharges treated effluent into the Mvudi River and Vuwani oxidation ponds which discharge into Dzindi River [19, 20, 29]. Nibamureke [27] found that high levels of Al in Albasini dam in excess of TQWR aquatic life guidelines were probably linked to a combination of leaching of bedrock (geology of area) by high rainfall and discharge of sewage effluent from Elim oxidation ponds [20]. The Al target water-quality range was established to safeguard the aquatic environment against the effect of toxic metals [30]. The high Al levels are a hazard to aquatic organism affecting their respiratory function and osmotic balance [17].

#### *4.1.2. Chromium (Cr)*

Water samples showed high levels of total Cr of 3679 μg/l at Nysvley in August 2001, and this sample point is downstream of Modimolle sewage plant [17]. The study by Edokpayi et al. [19, 21, 24, 28] showed high levels of Cr (total) in the Nzhelele, Ga-Selati, Mvudi, and Dzindi rivers in excess of the target water-quality range with the Mvudi River having

**Reference**

**Dam or** 

**aAlbasin i** 

**bFlag** 

**cNyl River**

**dSand** 

**eMvudi River**

**fDzindi River**

**River**

**River**

**River**

**River**

**μg/l**

**gMandzoro** 

**hNzhelele** 

**iGa-Selati** 

**jMawoni** 

**TQWR** 

**River**

**Boshielo** 

**dam**

**river**

**Name of** 

**Doringspruit**

**Elands &** 

**Nyl**

**Sand**

**Mvudi**

**Tshishushuru**

**Mandzoro**

**Nzhelele**

**Ga-Selati**

**Mawoni**

**Oliphant**

**River**

**Name of** 

**Elim**

**Marble** 

**Modimolle**

**Polokwane**

**Thohoyandou**

**Vuwani**

**Malamulele**

**Siloam**

**Phalaborwa** 

**Makhado**

**&** 

**Namakgale**

**Hall**

**sewage** 

**plant**

pH

A1 Cr (total)

Mn

Fe As Cd Cu Zn Pb Se **Table 1.**

–

–

0 – 11

–

–

–

Notes: – not available; bdl below detection limit; \*not more than 10% of background value; \*\*medium water hardness of CaCO3 with range 60 – 119 mg/l, aaverage of three

samples on the Albasini dam basin; bconsidered the sample point FBI; cconsidered the sample points along the Nyl River; drange in values; e,frange is values from Jan to Jun

2014; gdownstream sample point; hdownstream sample point; iconsidered the sum of wet and dry seasons; jconsidered the downstream sample point

Concentrations for trace metals (range OR mean) in selected freshwater impoundments and rivers in Limpopo receiving sewage effluent.

–

–

–

2

2

2 ± 1

–

0 – 175

90

bdl – 46

10 – 50

22 ± 0.09

1 – 13

60

0.01 – 3.40

0.5\*\*

http://dx.doi.org/10.5772/intechopen.76565

59

3 ± 2

–

0 – 1350

10 – 20

1 – 548

50 – 210

88 ± 38

42 – 131

–

0.97

2

– 113.4

–

–

0 – 729

10

11 – 567

30 – 50

420 ± 240

25.7 – 66

–

2.38

0.8\*\*

– 83.51

2 ± 1

–

0 – 24

10

0.2 – 4.3

–

<0.1

0.4 – 2

10

0.01 – 0.27

0.25\*\*

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

–

–

0 – 79

–

–

–

–

–

–

0.43 – 3.10 10

382 ± 62

2.4 – 27.5

0 – 19901

10 – 140

425 – 5070

790 – 1720

546 ± 50

1028

730

25.34

\*

– 6000.83

– 4991

6 ± 8

0.5 – 10.0

0 – 5047

50 – 680

29 – 675

80 – 200

–

52 – 545

210

1.02

180

– 2271.48

2 ± 0

–

0 – 3679

–

12 – 593

30 – 110

–

45 – 396

60

0.58

Cr6+7 and

– 46.04

Cr3+112

280 ± 0.075

10.5 – 11.9

0 – 2089

–

393 – 13810

200 – 400

–

1172

350

1.99

10

– 265.9

– 29094

7.5 ± 0.1

8.28 – 9.42

5.52 – 9.95

7.49 – 8.48

7.72 – 7.7

7.47 – 7.53

6.7 ± 0.3

7.21 – 7.76

7.72 – 9.81

7.35 – 9.07

6.5 – 9

**dam**

[27]

[23]

[17]

[28]

[19]

[26]

[21]

[24]

[24]

[33]

[30]


that discharge effluent either directly into the Oliphant River [15] or via some of tributaries such as the Elands River [23] and Ga-Selati River [24]. The Oliphant River is the most polluted river in South Africa and this is mainly due to mining activities, especially acid mine drainage, commercial and subsistence farming, and formal and informal residential

South Africa is a dry country, and rivers and streams flow during the rainy seasons. However, the location of sewage plants near streams and rivers means that the effluent is discharged into the streams and rivers and this contributes to base flow even during periods of no rainfall [20, 25]. The inflow from sewage effluents contributes to the build-up of trace metals in the freshwater environment. There are a number of studies that have shown the presence of trace metals on the freshwater environment (rivers and impoundments) in the Limpopo province of South Africa [15, 18–21, 24, 26–28]. In some cases, the trace metals are in excess of background levels, and the trace metals may become toxic to aquatic life and contaminate drinking water sources (**Table 1**). The pH values in the study sites were generally near the neutral, and therefore there was no contribution of metals due to the dissolution of bedrock or mining activities.

The study by Greenfield et al. [17] on the Nyl River system showed that the Al levels are higher than the target water-quality range (TWQR) of 10 μg/l during the study period. The presence of Al was attributed in part due to discharge of sewage effluent into the Groot Nyl River, a subtributary of the Nyl River, and rainfall-induced erosion of local bedrock. The study by Edokpayi et al. [19, 21, 24] showed variation in the Al level in the Ga-Selati, Nzhelele, Mvudi, and Dzindi Rivers in excess of the target water-quality range. The high level of Al may be attributed to the Thohoyandou sewage plant which discharges treated effluent into the Mvudi River and Vuwani oxidation ponds which discharge into Dzindi River [19, 20, 29]. Nibamureke [27] found that high levels of Al in Albasini dam in excess of TQWR aquatic life guidelines were probably linked to a combination of leaching of bedrock (geology of area) by high rainfall and discharge of sewage effluent from Elim oxidation ponds [20]. The Al target water-quality range was established to safeguard the aquatic environment against the effect of toxic metals [30]. The high Al levels are a hazard to aquatic organism affecting their respiratory function and osmotic balance [17].

Water samples showed high levels of total Cr of 3679 μg/l at Nysvley in August 2001, and this sample point is downstream of Modimolle sewage plant [17]. The study by Edokpayi et al. [19, 21, 24, 28] showed high levels of Cr (total) in the Nzhelele, Ga-Selati, Mvudi, and Dzindi rivers in excess of the target water-quality range with the Mvudi River having

discharges from municipal sewage plants [15, 25].

**4.1. Evidence of trace metal in freshwater environment**

**4. Results and discussion**

58 Sewage

*4.1.1. Aluminum (Al)*

*4.1.2. Chromium (Cr)*

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59

**Table 1.**

Concentrations for trace metals (range OR mean) in selected freshwater impoundments and rivers in Limpopo receiving sewage effluent.

higher Cr levels. The high levels of Cr in the rivers were attributed to sewage effluent discharge into the rivers as a result of inefficient metal removal during the wastewater treatment process [29]. The Cr level is in excess of the TWQR of Cr6+ (70 μg/l) and Cr3+ (120 μg/l) and is a threat to aquatic fauna [30, 31]. In the study by Shibambu et al. [32], the wastewater effluent flowed past a natural wetland which removed some of Cr and thus reducing Cr in the river water.

*4.1.6. Cadmium (Cd)*

*4.1.7. Copper (Cu)*

*4.1.8. Zinc (Zn)*

*4.1.9. Lead (Pb)*

organisms' enzymes and co-enzymes [39].

cesses in aquatic organisms [39].

The Cd levels of 21 and 22 μg/l were recorded at Klein and Groot Nyl rivers, respectively, in August 2002 (a period of no rainfall), indicating that part of As origins is geological other than sewage effluent discharge [17]. The sample point is also upstream of the Modimolle sewage plant. The studies by Seanego [18] and Edokpayi et al. [21, 24, 28] found high Cd levels in the Sand, Ga-Selati, Nzhelele, and Mvudi Rivers and attributed the high Cd values to discharge of sewage effluent to these rivers. The Cd level is in excess of the TWQR of 0.25 μg/l and is a threat to aquatic fauna especially fish [30, 37] and aquatic flora such as altering small heat

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61

The Cu levels in the range of 0–729 μg/l were recorded at Klein and Groot Nyl Rivers, respectively, in November 2001 (a period of rainfall), indicating that part of Cu origins is geological other than sewage effluent discharge [17]. High levels of Cu at 150 μg/l were recorded at Nysvley in November 2001, and this sample point is downstream of Modimolle sewage plant [17]. The studies of [18, 19, 21, 26, 28, 33] also found high Cu levels in the Mandzoro, Sand, Mawoni, Dzindi, Nzhelele, and Mvudi Rivers and attributed the high Cu values to discharge of sewage effluent to these rivers. The Cu level is in excess of the TWQR of 0.30 μg/l and is a threat to aquatic fauna especially fish [17, 30]. Copper is an essential component of aquatic

At Mosdene, the Zn levels of 1350 μg/l were recorded in August 2002 (a period of no rainfall), indicating that part of Zn origins is geological other than sewage effluent discharge [17]. The sample point is also downstream of the Modimolle sewage plant. The studies of [18, 19, 21, 26, 28, 33] also found high Zn levels in the Mandzoro, Sand, Mawoni, Dzindi, Nzhelele, and Mvudi Rivers and attributed the high Zn values to discharge of sewage effluent to these rivers. Nibamureke [27] found Zn levels just in water in excess of TQWR aquatic life guidelines and were unlikely to be a threat to aquatic life. The Zn level is in excess of the TWQR of 2 μg/l and is a threat to aquatic fauna especially the functioning of gills in fish [17, 30]. Zn at trace level is an essential component for biochemical and physiological pro-

The Pb levels in the range of 2–175 μg/l were recorded at sewage plant and other Nyl River sites, respectively, in November 2002 (a period of rainfall), indicating that part of Pb origins is geological other than sewage effluent discharge (Greenfield et al. [17]). The studies of [18, 19, 21, 26, 28, 33] also found high Pb levels in the Mandzoro, Sand, Mawoni, Dzindi, Nzhelele, and Mvudi Rivers and attributed the high Pb values to discharge of sewage effluent to these rivers. Nibamureke [27] showed that low levels of Pb in water were within the TQWR aquatic life guidelines and were no threat to aquatic life. The Pb level is in excess of the TWQR

shock protein (HSP) genes in aquatic midge *Chironomus riparius* [38].

#### *4.1.3. Manganese (Mn)*

At Mosdene sample point, the manganese levels were 5047 μg/l in March 2002 (a period of high rainfall), indicating that part of Mn origins is geological other than sewage effluent discharge [17]. This sample point Mosdene is also downstream of the Modimolle sewage plant, and part of the increased levels is probably from the sewage inflows. The studies of [18, 33] for the Sand and Mawoni Rivers also found that high levels of Mn were probably due to rainfall erosion of bedrock. The study by Edokpayi et al. [19, 21, 24, 28] showed high levels of Mn in the Nzhelele, Ga-Selati, Mvudi, and Dzindi Rivers in excess of the target water-quality range as a result of sewage discharge. The Mn level is in excess of the TWQR of 189 μg/l and is a threat to aquatic fauna especially fish [30, 33] and is an essential component in physiological processes of living organisms such as algae at trace levels [34].

#### *4.1.4. Iron (Fe)*

The Fe levels of 19,000 μg/l were recorded at Mosdene, in March 2002 (a period of high rainfall), indicating that part of Fe origins is geological other than sewage effluent discharge [17]. The sample point is also downstream of the Modimolle sewage plant. The study by Edokpayi et al. [19, 21, 24, 28] showed high levels of Fe in the Nzhelele, Ga-Selati, Mvudi, and Dzindi Rivers during the rainfall months of January to March 2014 and the Mvudi River having higher Fe levels and sewage effluent discharges. The studies of [18, 26, 32] for the Mandzoro, Sand, and Mawoni Rivers also found that high levels of Fe were probably due to rainfall erosion of bedrock. Nibamureke [27] found that high levels of Fe in water in excess of TQWR aquatic life guidelines were probably linked to a combination of leaching of bedrock (geology of area) by high rainfall and discharge of sewage effluent from Elim oxidation ponds [20]. The Fe level is within the guideline value range of 500 and 50,000 μg/l for freshwater [17]. Fe at trace level is an essential component of living organism including hemoglobin and myoglobin [35].

#### *4.1.5. Arsenic (As)*

The As levels of 79 μg/l were recorded at Mosdene on Nyl River, in August 2002 (a period of no rainfall), indicating that part of As origins is geological other than sewage effluent discharge [17]. The sample point is also downstream of the Modimolle sewage plant. The study by Shibambu [32] found low As levels in the Mawoni River downstream of a natural wetland showing the As removal as this was within the TWQR guideline values. The As level is in excess of the TWQR of 10 μg/l and is a threat to aquatic fauna especially fish [17, 30] and aquatic freshwater invertebrates such as *Daphnia magna* and *Ceriodaphnia dubia* [36].

#### *4.1.6. Cadmium (Cd)*

higher Cr levels. The high levels of Cr in the rivers were attributed to sewage effluent discharge into the rivers as a result of inefficient metal removal during the wastewater treatment process [29]. The Cr level is in excess of the TWQR of Cr6+ (70 μg/l) and Cr3+ (120 μg/l) and is a threat to aquatic fauna [30, 31]. In the study by Shibambu et al. [32], the wastewater effluent flowed past a natural wetland which removed some of Cr and thus reducing Cr in

At Mosdene sample point, the manganese levels were 5047 μg/l in March 2002 (a period of high rainfall), indicating that part of Mn origins is geological other than sewage effluent discharge [17]. This sample point Mosdene is also downstream of the Modimolle sewage plant, and part of the increased levels is probably from the sewage inflows. The studies of [18, 33] for the Sand and Mawoni Rivers also found that high levels of Mn were probably due to rainfall erosion of bedrock. The study by Edokpayi et al. [19, 21, 24, 28] showed high levels of Mn in the Nzhelele, Ga-Selati, Mvudi, and Dzindi Rivers in excess of the target water-quality range as a result of sewage discharge. The Mn level is in excess of the TWQR of 189 μg/l and is a threat to aquatic fauna especially fish [30, 33] and is an essential component in physiological

The Fe levels of 19,000 μg/l were recorded at Mosdene, in March 2002 (a period of high rainfall), indicating that part of Fe origins is geological other than sewage effluent discharge [17]. The sample point is also downstream of the Modimolle sewage plant. The study by Edokpayi et al. [19, 21, 24, 28] showed high levels of Fe in the Nzhelele, Ga-Selati, Mvudi, and Dzindi Rivers during the rainfall months of January to March 2014 and the Mvudi River having higher Fe levels and sewage effluent discharges. The studies of [18, 26, 32] for the Mandzoro, Sand, and Mawoni Rivers also found that high levels of Fe were probably due to rainfall erosion of bedrock. Nibamureke [27] found that high levels of Fe in water in excess of TQWR aquatic life guidelines were probably linked to a combination of leaching of bedrock (geology of area) by high rainfall and discharge of sewage effluent from Elim oxidation ponds [20]. The Fe level is within the guideline value range of 500 and 50,000 μg/l for freshwater [17]. Fe at trace level is an essential component of living organism including

The As levels of 79 μg/l were recorded at Mosdene on Nyl River, in August 2002 (a period of no rainfall), indicating that part of As origins is geological other than sewage effluent discharge [17]. The sample point is also downstream of the Modimolle sewage plant. The study by Shibambu [32] found low As levels in the Mawoni River downstream of a natural wetland showing the As removal as this was within the TWQR guideline values. The As level is in excess of the TWQR of 10 μg/l and is a threat to aquatic fauna especially fish [17, 30] and

aquatic freshwater invertebrates such as *Daphnia magna* and *Ceriodaphnia dubia* [36].

processes of living organisms such as algae at trace levels [34].

the river water.

60 Sewage

*4.1.4. Iron (Fe)*

hemoglobin and myoglobin [35].

*4.1.5. Arsenic (As)*

*4.1.3. Manganese (Mn)*

The Cd levels of 21 and 22 μg/l were recorded at Klein and Groot Nyl rivers, respectively, in August 2002 (a period of no rainfall), indicating that part of As origins is geological other than sewage effluent discharge [17]. The sample point is also upstream of the Modimolle sewage plant. The studies by Seanego [18] and Edokpayi et al. [21, 24, 28] found high Cd levels in the Sand, Ga-Selati, Nzhelele, and Mvudi Rivers and attributed the high Cd values to discharge of sewage effluent to these rivers. The Cd level is in excess of the TWQR of 0.25 μg/l and is a threat to aquatic fauna especially fish [30, 37] and aquatic flora such as altering small heat shock protein (HSP) genes in aquatic midge *Chironomus riparius* [38].

#### *4.1.7. Copper (Cu)*

The Cu levels in the range of 0–729 μg/l were recorded at Klein and Groot Nyl Rivers, respectively, in November 2001 (a period of rainfall), indicating that part of Cu origins is geological other than sewage effluent discharge [17]. High levels of Cu at 150 μg/l were recorded at Nysvley in November 2001, and this sample point is downstream of Modimolle sewage plant [17]. The studies of [18, 19, 21, 26, 28, 33] also found high Cu levels in the Mandzoro, Sand, Mawoni, Dzindi, Nzhelele, and Mvudi Rivers and attributed the high Cu values to discharge of sewage effluent to these rivers. The Cu level is in excess of the TWQR of 0.30 μg/l and is a threat to aquatic fauna especially fish [17, 30]. Copper is an essential component of aquatic organisms' enzymes and co-enzymes [39].

#### *4.1.8. Zinc (Zn)*

At Mosdene, the Zn levels of 1350 μg/l were recorded in August 2002 (a period of no rainfall), indicating that part of Zn origins is geological other than sewage effluent discharge [17]. The sample point is also downstream of the Modimolle sewage plant. The studies of [18, 19, 21, 26, 28, 33] also found high Zn levels in the Mandzoro, Sand, Mawoni, Dzindi, Nzhelele, and Mvudi Rivers and attributed the high Zn values to discharge of sewage effluent to these rivers. Nibamureke [27] found Zn levels just in water in excess of TQWR aquatic life guidelines and were unlikely to be a threat to aquatic life. The Zn level is in excess of the TWQR of 2 μg/l and is a threat to aquatic fauna especially the functioning of gills in fish [17, 30]. Zn at trace level is an essential component for biochemical and physiological processes in aquatic organisms [39].

#### *4.1.9. Lead (Pb)*

The Pb levels in the range of 2–175 μg/l were recorded at sewage plant and other Nyl River sites, respectively, in November 2002 (a period of rainfall), indicating that part of Pb origins is geological other than sewage effluent discharge (Greenfield et al. [17]). The studies of [18, 19, 21, 26, 28, 33] also found high Pb levels in the Mandzoro, Sand, Mawoni, Dzindi, Nzhelele, and Mvudi Rivers and attributed the high Pb values to discharge of sewage effluent to these rivers. Nibamureke [27] showed that low levels of Pb in water were within the TQWR aquatic life guidelines and were no threat to aquatic life. The Pb level is in excess of the TWQR of 0.5 μg/l and is a threat to aquatic fauna especially the functioning of gills in fish [17, 30] and is considered a non-essential component in biological systems [39].

#### *4.1.10. Selenium (Se)*

The study by Greenfield et al. [17] found low Se levels in the Nyl River and attributed Se content to factors such as diffuse pollution and chemical weathering of bedrock. The leaching of Se from farmlands into the aquatic environment is a result of rainfall or irrigation that is practiced in the study area. Se is found in synthetic pesticides used in the study area. Shibambu [33] showed low levels of Se in the Mawoni River and were within the TQWR aquatic life guidelines and also showing the removal of Se by the natural wetland. However, high Se levels are toxic and may induce skeletal deformities in animals [17].

#### **4.2. Trace metals in sludge of selected municipal sewage plants in Limpopo**

A number of studies have been conducted in Limpopo to determine the metal removal efficiency of municipal sewage plants [18, 19, 26]. The metal efficiencies were generally low for these metals as high levels were found in the dried sludge (**Table 2**). The trace metals, Zn, Pb, and Cu, exceed the maximum permissible Department of Water Affairs & Forestry (DWAF) guidelines, and the metals have a significant environmental impact.

The studies by Baloyi et al. [26] and Shamuyarira [41] showed that Cu and Zn contents were very high. The application of sludge rich in Cu and Zn as this case to agricultural land may result in leaching to the aquatic environment in the event of rainfall event or during irrigation. At minute quantities, Cu and Zn are essential elements and are necessary for plant growth [11]. Thus, a careful application of sludge to agricultural land is required in order to safeguard the aquatic environment, taking into account the presence of Cu or Zn content of the land. The Co content was variable among the sewage plants and showed no discernible trend. At high levels, Co is harmful to plants but is an essential element at trace levels in enzymatic biochemical reactions [42].

The Pb content in sludge was generally low with the exception of Louis Trichardt which had Pb content greatly exceeding the maximum DWAF guidelines [40]. Pb has no known nutritional function in plant growth and thus is a potential hazard to the plants and crops that may be grown on the agricultural land. The presence of Cu, Zn, and Fe in wastewater streams and eventually in the sludge may be due to household use of brass (copper and zinc), copper, and iron scrubbers in washing of cooking pots [26].

The presence of high Pb in wastewater and then in the sludge for Polokwane and Louis Trichardt may be due to a dense vehicular traffic. In a 15-year study by Iglesias et al. [43] in Spain, they showed that the sludge application to agricultural land resulted in an increase in Pb, Hg, Zn, and Ag in treated soils and Cu, Pb, and Zn contents in maize and barley crops which was similar to the control site. In a similar study in South Africa, Ogbazghi et al. [44] also found a similar trend of increase in metals, Zn, Cd, Ni, and Pb soils, amended with sludge in a 10-year study.

Another trace metal of interest is silver and aluminum in municipal dried sludge, since in these urban towns, there are no heavy metal-intensive industries (**Table 2**). The presence of Ag in the sludge may be attributed to the use of silver nanoproducts. The study by Shamuyarira and **Reference** **Trace metals (mg/**

**Thohoyandou** 

**Polokwane** 

**Tzaneen** 

**Louis Trichardt** 

**Musina** 

**Malamulele** 

**DWAF\***

**Total maximum** 

**Maximum** 

**permissible level**

**threshold**

**sewage plant**

**sewage** 

**plant**

**sewage plant**

**sewage plant**

**sewage plant**

**sewage plant**

**kg dry mass)**

Al Fe Mn

As Ni Cr (total)

Cd

Pb Cu Zn Ag Hg

V Se Mo

Co **Table 2.**

12.0 ± 0.0

53 ± 0.2

5.6 ± 0.2 Notes: \*DWAF guidelines for metal limit receiving high sludge loads; \*\*Exceeds DWAF guidelines; – not available.

Average concentrations for trace metals from selected sewage sludge in Limpopo.

12.6 ± 0.0

4.7 ± 03

NA

–

–

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63

3.0 ± 0.0

9.8 ± 0.2

5.0 ± 0.2

5.9 ± 0.0

20.1 ± 0.0

NA

–

–

4.1 ± 0.1

4.0 ± 0.4

4.1 ± 1.2

4.9 ± 0.4

5.4 ± 0.1

NA

–

–

70.6 ± 0.6

39.3 ± 0.1

28.0 ± 1.1

57.4 ± 0.7

70.2 ± 2.0

NA

–

–

6.1 ± 0.1 1.1 ± 0.0

1.2 ± 0.1

1.4 ± 0.1

1.7 ± 0.1

1.1 ± 0.0

NA

1

9

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

6.9 ± 0.1

13.4 ± 0.5

21.9 ± 0.4

7.1 ± 0.0

NA

–

–

378.0 ± 3.5\*\*

1193 ± 28\*\*

1552 ± 35\*\*

951 ± 36\*\*

1732 ± 5\*\*

1032 ± 21\*\*

821 ± 124\*\*

200

700

324.8 ± 2.8

263.7 ± 9.1

499.3 ± 1.7\*\*

626.0 ± 5.0\*\*

178 ± 23

120

375

35.6 ± 0.1

103.8 ± 3.8

52.3 ± 2.4

172.9 ± 0.9\*\*

21.3 ± 0.8

18.4 ± 3.6

100

150

0.82 ± 0.03

3.11 ± 0.16

1.39 ± 0.06

1.66 ± 0.09

1.06 ± 0.04

2.7 ± 0.4

3

5

64.4 ± 0.7

134.5 ± 5.2

53.5 ± 2.4

97.1 ± 2.2

35.1 ± 1.6

NA

350

450

33.9 ± 0.1

47.3 ± 1.3

31.3 ± 1.7

514 ± 0.6

35.2 ± 1.0

NA

150

200

2.6 ± 0.1

5.1 ± 0.1

4.2 ± 0.1

3.3 ± 0.2

4.8 ± 0.0

NA

2

20

629 ± 10

263 ± 0

288 ± 7

1348 ± 29

201 ± 17

NA

–

–

13388 ± 293 29228 ± 491

10080 ± 57

18085 ± 509

19273 ± 223

8000 ± 750

11337 ± 1057

–

–

12238 ± 357

11953 ± 470

12583 ± 173

6958 ± 272

NA

–

–

[41]

[41]

[41]

[41]

[41]

[26]

[40]


of 0.5 μg/l and is a threat to aquatic fauna especially the functioning of gills in fish [17, 30] and

The study by Greenfield et al. [17] found low Se levels in the Nyl River and attributed Se content to factors such as diffuse pollution and chemical weathering of bedrock. The leaching of Se from farmlands into the aquatic environment is a result of rainfall or irrigation that is practiced in the study area. Se is found in synthetic pesticides used in the study area. Shibambu [33] showed low levels of Se in the Mawoni River and were within the TQWR aquatic life guidelines and also showing the removal of Se by the natural wetland. However, high Se

A number of studies have been conducted in Limpopo to determine the metal removal efficiency of municipal sewage plants [18, 19, 26]. The metal efficiencies were generally low for these metals as high levels were found in the dried sludge (**Table 2**). The trace metals, Zn, Pb, and Cu, exceed the maximum permissible Department of Water Affairs & Forestry (DWAF)

The studies by Baloyi et al. [26] and Shamuyarira [41] showed that Cu and Zn contents were very high. The application of sludge rich in Cu and Zn as this case to agricultural land may result in leaching to the aquatic environment in the event of rainfall event or during irrigation. At minute quantities, Cu and Zn are essential elements and are necessary for plant growth [11]. Thus, a careful application of sludge to agricultural land is required in order to safeguard the aquatic environment, taking into account the presence of Cu or Zn content of the land. The Co content was variable among the sewage plants and showed no discernible trend. At high levels, Co is harmful to plants but is an essential element at trace levels in enzymatic biochemical reactions [42].

The Pb content in sludge was generally low with the exception of Louis Trichardt which had Pb content greatly exceeding the maximum DWAF guidelines [40]. Pb has no known nutritional function in plant growth and thus is a potential hazard to the plants and crops that may be grown on the agricultural land. The presence of Cu, Zn, and Fe in wastewater streams and eventually in the sludge may be due to household use of brass (copper and zinc), copper, and

The presence of high Pb in wastewater and then in the sludge for Polokwane and Louis Trichardt may be due to a dense vehicular traffic. In a 15-year study by Iglesias et al. [43] in Spain, they showed that the sludge application to agricultural land resulted in an increase in Pb, Hg, Zn, and Ag in treated soils and Cu, Pb, and Zn contents in maize and barley crops which was similar to the control site. In a similar study in South Africa, Ogbazghi et al. [44] also found a similar trend of increase in metals, Zn, Cd, Ni, and Pb soils, amended with sludge in a 10-year study. Another trace metal of interest is silver and aluminum in municipal dried sludge, since in these urban towns, there are no heavy metal-intensive industries (**Table 2**). The presence of Ag in the sludge may be attributed to the use of silver nanoproducts. The study by Shamuyarira and

is considered a non-essential component in biological systems [39].

levels are toxic and may induce skeletal deformities in animals [17].

guidelines, and the metals have a significant environmental impact.

iron scrubbers in washing of cooking pots [26].

**4.2. Trace metals in sludge of selected municipal sewage plants in Limpopo**

*4.1.10. Selenium (Se)*

62 Sewage

**Table 2.**

Average concentrations for trace metals from selected sewage sludge in Limpopo.

Gumbo [6] of five selected municipal plants in the Limpopo province of South Africa found that silver was in the range of 6.13 ± 0.12 mg/kg dry mass to 21.93 ± 0.38 mg/kg dry mass. A recent study by Mackevica et al. [45] in Denmark showed that the maximum silver nanoparticles per toothbrush were released into the wastewater during a normal toothbrush exercise and were 10.2 ng silver content. The commercial toothbrushes are embeded with silver nanoparticles, and the adult and children toothbrush had a total silver content of 16.07 ± 0.11 and 13.53 ± 0.04 g for the whole tooth brush, respectively. Based on these studies, it can be assumed that most of the nanosilver and silver, which is used domestically, finds its way to the municipal sewage plants [6, 46] or to the environment if there is no municipal sewage plant connection as in most rural areas of developing countries [12]. The silver content of sewage wastewater is lower in comparison with sewage sludge since the silver is adsorbed onto sewage biomass to form insoluble silver sulfide (Ag<sup>2</sup> S) [47]. Thus, the hazard may arise when the sludge is applied on farmland as fertilizer. A recent study by Wu et al. [13] in China, showed under pH conditions, metal promoters Cu and Zn, aerobic conditions, and the presence of sulfur-dominated amino acids, that the insoluble Ag<sup>2</sup> S might become mobile and available for uptake by crops such as wheat mostly than in brown rice.

In South Africa, the Department of Water & Sanitation has not developed guideline values for silver in the sewage sludge or the disposal of sewage containing silver [48]. Elsewhere in the United States of America, the Environment Protection Agency has regulated silver ion generators as pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) but not silver in sewage sludge [36, 49]. In the European Union, the biosolids directive (sewage sludge directive 86/278/EEC) states that all biocides that contain silver should be screened and approved by May 14, 2014 [50].

Aluminium is another trace metal that is also found in high concentrations in the dried municipal sludge in excess of 6900 mg/kg (**Table 2**). The origin of Al in the domestic wastewater is probable probably the use of deodorants that contain Al as shown by the study of Modika [51] or the use of Al cookware where upon washing releases Al in the wastewater [52]. In a separate case studied by Modika [51], in South Africa, the Ag and Al contents in wastewater were in the range of 0.03–0.52 ppb and 0.03–0.21 ppm, respectively, over the 5-day period. The Ag and Al contents in soap B were found to be <0.032 ppb and 0.07 ppm, respectively. The Nivea deodorant spray had the silver and aluminum of 7.03 ppb and 124.88 ppm, respectively. The wastewater was disposed to the natural environment since in the village there is no municipal sewerage connection.

#### **4.3. Trace metals in sediments of impoundments and rivers receiving sewage effluent**

The sewage effluent rich in metals is discharged into rivers and streams, and the metals either stay in solution or are trapped in complex sediments and pollution sinks [53]. The metals in the sediments can be released back into the water column should the environmental conditions change, such as pH becoming acidic, with devastating consequences on aquatic life and human health [15, 54] or during flood conditions [55]. The pH values in the study sites were generally near the neutral to alkaline, and therefore there was no contribution of metals due to the dissolution of bedrock or mining activities (**Table 3**). The trace metals that are likely to have an impact on aquatic life are Cd, Cr, V, Pb, Ni, and Zn.

**Trace** 

a

[27] **mg/kg** 

b

[18] **mg/**

c

[28] **mg/kg dry** 

d[21] **mg/**

e

[15] **mg/kg** 

e

[15] **mg/kg** 

e

[15] **mg/kg** 

e

[15] **mg/kg dry** 

**Australian and** 

**New Zealand** 

**(ANZECC)**

[56] **mg/kg dry** 

**weight**

**weight Average** 

**concentration**

**dry weight** 

**Average** 

**concentration**

**dry weight** 

**Average** 

**concentration**

**dry weight** 

**weight range** 

**kg dry** 

**weight range** 

**Average** 

**concentration**

**concentration**

**concentration**

**metals** 

**dry weight** 

**kg dry** 

**weight range** 

**concentration**

**(mg/**

**Average** 

**concentration**

**kg dry** 

**weight)**

**Name of** 

**Doringspruit** 

**Sand**

**Mvudi**

**Nzhelele**

**Ga-Selati**

**Oliphant River** 

**Letaba River,** 

**Luvuvhu** 

**Low** 

**High** 

**River, enters** 

**risk**

**risk**

**KNP**

**enters KNP**

**@ Phalaborwa** 

**a barrage**

**River or** 

**flows into** 

**dam**

**Name of** 

**Elim**

**Polokwane**

**Thohoyandou**

**Siloam**

**Namakgale,** 

**Upstream** 

**Malamulele**

**Thohoyandou**

**Freshwater &** 

**reservoirs**

**sewage plants**

**Phalaborwa**

**sewage** 

**plant**

pH\*

Al Cr (total)

Mn

Fe As Cd Cu Zn Pb Ni Co

V **Table 3.**

0.583 ± 0.079

–

–

–

310.17 Notes: bdl: below detection limit; – not available; KNP: Kruger National Park; \*pH is for water column above the sediments; arange is for the 2 samples sites; brange is for

the 8 sample sites; c,drange is values from Jan to Jun 2014; enormalised to 10% taking into account background values.

Concentrations for trace metals in sediments of selected freshwater impoundments and rivers in Limpopo receiving sewage effluent.

558.28

175.01

360.67

–

–

0.279 ± 0.006

–

–

–

135.7

84.67

5.75

81.75

–

–

http://dx.doi.org/10.5772/intechopen.76565

65

0.161 ± 0.033

–

–

–

562.19

334.97

116.15

175.52

21

52

0.426 ± 0.024

0.71 – 3.38

1.17 – 8.37

0.248 – 2.71

30.05

25.12

15.75

17.07

50

220

0.412 ± 0.009

6.67 – 15

9.78 – 1524

2.605 – 202

155.09

139.57

71.6

88.96

200

410

0.260 ± 0.056

0.89 – 2.28

7.68 – 5690

2.182 – 566

174.47

195.4

68.41

158.69

65

270

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

0.058 ± 0.041

0.0192 – 0.0284

bdl – 2.189

0.006 – 4.056

0.16

0.09

0.19

0.12

1.5

10

–

–

–

–

18.42

16.75

14.96

15.15

20

70

196.128 ± NA

25.6 – 256.4

2900 – 7460

1175 – 5252

164778.67

148875.04

62050.25

110603.95

–

4.801 ± 0.185

39.3 – 225

160 – 2160

120 – 516

3295.57

1209.61

1352.38

2019.72

–

–

0.337 ± 0.045

–

31.96 – 175

7.804 – 51.288

969.29

623.41

270.48

312.58

80

370

136.660 ± NA

–

4080 – 9090

2331 – 4707

145392.94

93046.9

23865.48

36066.5

–

–

7.34 – 7.63

7.49 – 8.30

7.3 – 7.7

7.21 – 7.76

8.7

8.6

8.1

8.1

6.5

8.0

**Albasini dam**


Gumbo [6] of five selected municipal plants in the Limpopo province of South Africa found that silver was in the range of 6.13 ± 0.12 mg/kg dry mass to 21.93 ± 0.38 mg/kg dry mass. A recent study by Mackevica et al. [45] in Denmark showed that the maximum silver nanoparticles per toothbrush were released into the wastewater during a normal toothbrush exercise and were 10.2 ng silver content. The commercial toothbrushes are embeded with silver nanoparticles, and the adult and children toothbrush had a total silver content of 16.07 ± 0.11 and 13.53 ± 0.04 g for the whole tooth brush, respectively. Based on these studies, it can be assumed that most of the nanosilver and silver, which is used domestically, finds its way to the municipal sewage plants [6, 46] or to the environment if there is no municipal sewage plant connection as in most rural areas of developing countries [12]. The silver content of sewage wastewater is lower in comparison with sewage sludge since the silver is adsorbed onto sewage biomass to form

farmland as fertilizer. A recent study by Wu et al. [13] in China, showed under pH conditions, metal promoters Cu and Zn, aerobic conditions, and the presence of sulfur-dominated amino

In South Africa, the Department of Water & Sanitation has not developed guideline values for silver in the sewage sludge or the disposal of sewage containing silver [48]. Elsewhere in the United States of America, the Environment Protection Agency has regulated silver ion generators as pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) but not silver in sewage sludge [36, 49]. In the European Union, the biosolids directive (sewage sludge directive 86/278/EEC) states that all biocides that contain silver should be screened

Aluminium is another trace metal that is also found in high concentrations in the dried municipal sludge in excess of 6900 mg/kg (**Table 2**). The origin of Al in the domestic wastewater is probable probably the use of deodorants that contain Al as shown by the study of Modika [51] or the use of Al cookware where upon washing releases Al in the wastewater [52]. In a separate case studied by Modika [51], in South Africa, the Ag and Al contents in wastewater were in the range of 0.03–0.52 ppb and 0.03–0.21 ppm, respectively, over the 5-day period. The Ag and Al contents in soap B were found to be <0.032 ppb and 0.07 ppm, respectively. The Nivea deodorant spray had the silver and aluminum of 7.03 ppb and 124.88 ppm, respectively. The wastewater was disposed to the natural environment since in the village there is no municipal sewerage connection.

**4.3. Trace metals in sediments of impoundments and rivers receiving sewage effluent**

have an impact on aquatic life are Cd, Cr, V, Pb, Ni, and Zn.

The sewage effluent rich in metals is discharged into rivers and streams, and the metals either stay in solution or are trapped in complex sediments and pollution sinks [53]. The metals in the sediments can be released back into the water column should the environmental conditions change, such as pH becoming acidic, with devastating consequences on aquatic life and human health [15, 54] or during flood conditions [55]. The pH values in the study sites were generally near the neutral to alkaline, and therefore there was no contribution of metals due to the dissolution of bedrock or mining activities (**Table 3**). The trace metals that are likely to

S) [47]. Thus, the hazard may arise when the sludge is applied on

S might become mobile and available for uptake by crops such as

insoluble silver sulfide (Ag<sup>2</sup>

64 Sewage

acids, that the insoluble Ag<sup>2</sup>

wheat mostly than in brown rice.

and approved by May 14, 2014 [50].

**Table 3.** Concentrations for trace metals in sediments of selected freshwater impoundments and rivers in Limpopo receiving sewage effluent. Nibamureke [27] found high levels of Fe and Al in sediments in excess of TQWR aquatic life guidelines which were probably linked to rainfall that may have occurred during the sampling trip (**Table 4**). However, the near neutral pH of the water samples would imply that the Al and Fe would not be available for uptake by the fish and cause harm especially to the gills. Nibamureke [27] showed that the high Cr (0.337 mg/l) levels would likely affect fish health as shown by changes in blood variables (hematocrit and plasma proteins) and were consistent with Cr exposure. The Cr ions are toxic since the alkaline pH contributes to the availability of Cr in sediments and becomes available in the water column.

Nibamureke [27] concluded that Cu levels were not harmful to fish health since the high Cu levels were transitional as a result of rainfall events that occurred during the sampling period. Also, other variables such as dissolved oxygen, total hardness metals (Ca and Mg), and Zn compete with Cu in fish physiology, thus reducing Cu toxicity [30]. Nibamureke [27] concluded that Mn levels in the sediments were likely to be harmful to fish health as a result of Mn becoming soluble due to alkaline pH. Though Mn is an essential metal in fish health, higher levels become toxic and cause reduced red and white blood cells, causing damage to kidney and spleen [27].

Nibamureke [27] showed that a high Pb level in the sediment is a cause of concern since Pb has been implicated in endocrine disruption chemical. However, other variables such as low DO levels and hardness (Ca and Mg) metals tend to inhibit Pb toxicity in fish, thus preventing its bioavailability [27]. Thus, the presence of Pb in the sediments may be linked to sewage inflows originating from Elim oxidation ponds and leaching from surrounding farms [20]. The levels of Cd in sediments are harmful to aquatic life. The Cd metal accumulates in the sediment and may become toxic to aquatic life such as *C. riparius* since these midge larvae live at the bottom sediments [38]. Their study showed that at laboratory exposure of 18.33 mg/l, Cd treatment altered the gene profile of small heat shock proteins (sHSPs). These sHSPs protect the organism against adverse conditions that may be encountered such as high Cd levels found in the sediments.

#### **4.4. Impact of metal on aquatic environment**

There are a number of studies that have shown the impact of trace metals on aquatic flora (plants) and aquatic fauna [15, 18, 27]. The study by Nibamureke [27] on fish species, *Clarias griepinus, Coptodon rendalli,* and *Oreochromis mossambicus* on their health from Albasini dam showed the presence of trace metals and so on. The source of trace metals is probably the effluent discharge from Elim sewage plant into Doringspruit River which then flows into Albasini dam [20].

Gumbo et al. [20], they showed the presence of algae in the Sand River and the Albasini dam as a result of the availability of nutrients. The source of Fe in the body mass of *O. mossambicus* was in part attributed to bedrock of the Sand River which is dominated by the granite which on weathering produces Fe and Mn [18] and effluent discharge from Polokwane sewage plant

**Table 4.** Average and range concentrations for trace metals in fish in freshwater impoundments and rivers in Limpopo

**Sand River**  [18] **range concentration**

**Doringspruit River Sand River Elands & Oliphant Oliphant**

*C. gariepinus O. mossambicus O. mossambicus O. mossambicus O. mossambicus*

**Elim Polokwane Marble Hall** 

Al 0.813 ± 0.199 0.911 ± 0.291 – 59.8 59.4 Cr (total) – – – 36.9 13.5 Mn 0.012 ± 0.002 0.021 ± 0.009 113.6 – 290.9 5.3 15.3 Fe 0.241 ± 0.064 0.247 ± 0.079 1286 – 3429 647 125 As – – 0.7 0.0 Cd – – 0.0898 0.0 0.2 Cu 0.009 ± 0.001 0.012 ± 0.004 8 – 14 10.5 4.9 Zn 0.202 ± 0.025 0.243 ± 0.042 78 – 159 25.8 214 Pb 0.003 ± 0.000 0.003 ± 0.000 – 4 4.8 Ni – – – 2 4.9 Co – – – 2 0.4 Se – – – 1.7 2

**Flag Boshielo dam –** [57] **Average concentration**

http://dx.doi.org/10.5772/intechopen.76565

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

**& upstream of Oliphant Rivers** **Phalaborwa barrage** [57] **Average concentration**

67

**Sewage plants upstream of Oliphant River**

Another hypothesis advanced by Oberholster et al. [58] was that the consumption of algae with Al led to a drop in pH to 2.9 in the stomach of *O. mossambicus,* thus contributing to the Al bioavailability. The same process of biomagnification in the food chain may be occurring with fish in Albasini dam and may account for the high Al and Fe levels in fish body muscles. Again in the same study by Oberholster et al., they found evidence of yellow fat which was associated with a high Al level in the *O. mossambicus* fish, and the yellow fat is associated with pansteatitis. The pansteatitis has been linked with the death of crocodiles and fish in the Kruger National Park [15]. The studies by Seanego [18] and Nibamureke [27] did not show if this condition of pansteatitis was occurring within the *O. mossambicus* fish in the Albasini dam

rich in Fe and Mn since there are high levels of Fe and Mn in the sewage sludge [41].

or in the Sand River.

Notes: – not available.

receiving sewage effluent.

**Trace metals (mg/kg)**

**Name of River**

**Name of sewage plant**

**Fish muscle** **Albasini dam** [27] **Average** 

**concentration**

The studies by Seanego [18] and Nibamureke [27] showed that the metals, Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Pb, V, and Zn, were present in fish body in various organs (**Table 4**). These metals contribute to the well-being of the fish at trace levels. However, there are two metals, Al and Fe that were in toxic levels and were likely to cause histopathological damage to the fish as shown from the study by Nibamureke [27]. The study by Seanego [18] on the Sand River, the Limpopo province of South Africa, also found high Fe levels in the body mass of *O. mossambicus* fish.

In another study in Loskop dam, South Africa, Oberholster et al. [58] showed that the Al and Fe bioaccumulate in algae which in turn is consumed by *O. mossambicus* as part of their diet and the Al and Fe are now present in the fish. In a separate study by Magonono [59] and


Nibamureke [27] found high levels of Fe and Al in sediments in excess of TQWR aquatic life guidelines which were probably linked to rainfall that may have occurred during the sampling trip (**Table 4**). However, the near neutral pH of the water samples would imply that the Al and Fe would not be available for uptake by the fish and cause harm especially to the gills. Nibamureke [27] showed that the high Cr (0.337 mg/l) levels would likely affect fish health as shown by changes in blood variables (hematocrit and plasma proteins) and were consistent with Cr exposure. The Cr ions are toxic since the alkaline pH contributes to the availability of

Nibamureke [27] concluded that Cu levels were not harmful to fish health since the high Cu levels were transitional as a result of rainfall events that occurred during the sampling period. Also, other variables such as dissolved oxygen, total hardness metals (Ca and Mg), and Zn compete with Cu in fish physiology, thus reducing Cu toxicity [30]. Nibamureke [27] concluded that Mn levels in the sediments were likely to be harmful to fish health as a result of Mn becoming soluble due to alkaline pH. Though Mn is an essential metal in fish health, higher levels become toxic and cause reduced red and white blood cells, causing damage to kidney and spleen [27].

Nibamureke [27] showed that a high Pb level in the sediment is a cause of concern since Pb has been implicated in endocrine disruption chemical. However, other variables such as low DO levels and hardness (Ca and Mg) metals tend to inhibit Pb toxicity in fish, thus preventing its bioavailability [27]. Thus, the presence of Pb in the sediments may be linked to sewage inflows originating from Elim oxidation ponds and leaching from surrounding farms [20]. The levels of Cd in sediments are harmful to aquatic life. The Cd metal accumulates in the sediment and may become toxic to aquatic life such as *C. riparius* since these midge larvae live at the bottom sediments [38]. Their study showed that at laboratory exposure of 18.33 mg/l, Cd treatment altered the gene profile of small heat shock proteins (sHSPs). These sHSPs protect the organism against adverse conditions that may be encountered such as high Cd levels

There are a number of studies that have shown the impact of trace metals on aquatic flora (plants) and aquatic fauna [15, 18, 27]. The study by Nibamureke [27] on fish species, *Clarias griepinus, Coptodon rendalli,* and *Oreochromis mossambicus* on their health from Albasini dam showed the presence of trace metals and so on. The source of trace metals is probably the effluent discharge from Elim sewage plant into Doringspruit River which then flows into Albasini dam [20].

The studies by Seanego [18] and Nibamureke [27] showed that the metals, Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Pb, V, and Zn, were present in fish body in various organs (**Table 4**). These metals contribute to the well-being of the fish at trace levels. However, there are two metals, Al and Fe that were in toxic levels and were likely to cause histopathological damage to the fish as shown from the study by Nibamureke [27]. The study by Seanego [18] on the Sand River, the Limpopo province of South Africa, also found high Fe levels in the body mass of *O. mossambicus* fish.

In another study in Loskop dam, South Africa, Oberholster et al. [58] showed that the Al and Fe bioaccumulate in algae which in turn is consumed by *O. mossambicus* as part of their diet and the Al and Fe are now present in the fish. In a separate study by Magonono [59] and

Cr in sediments and becomes available in the water column.

found in the sediments.

66 Sewage

**4.4. Impact of metal on aquatic environment**

**Table 4.** Average and range concentrations for trace metals in fish in freshwater impoundments and rivers in Limpopo receiving sewage effluent.

Gumbo et al. [20], they showed the presence of algae in the Sand River and the Albasini dam as a result of the availability of nutrients. The source of Fe in the body mass of *O. mossambicus* was in part attributed to bedrock of the Sand River which is dominated by the granite which on weathering produces Fe and Mn [18] and effluent discharge from Polokwane sewage plant rich in Fe and Mn since there are high levels of Fe and Mn in the sewage sludge [41].

Another hypothesis advanced by Oberholster et al. [58] was that the consumption of algae with Al led to a drop in pH to 2.9 in the stomach of *O. mossambicus,* thus contributing to the Al bioavailability. The same process of biomagnification in the food chain may be occurring with fish in Albasini dam and may account for the high Al and Fe levels in fish body muscles. Again in the same study by Oberholster et al., they found evidence of yellow fat which was associated with a high Al level in the *O. mossambicus* fish, and the yellow fat is associated with pansteatitis. The pansteatitis has been linked with the death of crocodiles and fish in the Kruger National Park [15]. The studies by Seanego [18] and Nibamureke [27] did not show if this condition of pansteatitis was occurring within the *O. mossambicus* fish in the Albasini dam or in the Sand River.

#### **4.5. Human health-risk assessment**

The consumption of fish by rural communities in South Africa is on the increase since fish is an affordable protein source in comparison with other animal or plant protein sources [60]. The fish are provided by illegal fisherman or from small-holder fish farms that are located in the Limpopo province [61, 62]. However, for wild stock fisheries, a number of studies in South Africa have shown that the popular *O. mossambicus* fish is contaminated with metals such as Al, Fe, and Pb at toxic levels [18, 27, 57, 58]. Thus, studies have been conducted to evaluate human health-risk assessment of the consumption of fish contaminated with toxic metal (**Table 5**).

The average daily dose (ADD) is expressed in mg/kg human body mass per day from this expression (1) as per the procedure by Addo-Bediako et al. [57].

$$\begin{array}{l} \text{(\"average\" )} \quad \text{(\"average\" )} \quad \text{(\"average\" )} \quad \text{(\"average\" )} \quad \text{(\"average\" )} \quad \text{(\"average\" )} \\\\ \text{expression (1) as per the procedure by Addo-Bediakov et al. [57].} \\\\ \text{ADD} = \frac{\text{(average metal in fish muscle (fw))} \times \text{(mass of fish consumed)}}{\text{(adult body mass)} \times \text{(number of days in between fish metals)}} \end{array} \tag{1}$$

where the average metal concentration (mg/kg) in fish muscle, mass of fish consumed (kg) was 0.150 kg portion once per 7 days, adult body mass (kg) was 70 kg, and days is the number of day in between fish meals.

The hazard quotient (HQ) for fish from the Albasini dam and the Sand River was calculated from the data that were provided on the trace metals in the fish muscles based on the procedure by Addo-Bediako et al. [57]. The assumptions were that an individual would eat 150 g of fish per week and the adult body mass was 70 kg as per the study by Addo-Bediako et al. [57]. The studies clearly showed the high levels of trace metals in the fish muscle, and these metals, Cr, Pb, and Sb [57] and Fe and Pb [18], were likely to affect human health (**Table 5**). The human-risk assessment (HQ) was near 1 or was above 1 and thus posed hazard to fish consumers near the Phalaborwa Barrage, Flag Boshielo dam, and the Sand River.

The presence of Cr poses human health issues especially the Cr6+ ion which is toxic and carcinogenic to humans [39]. The presence of Pb is a serious concern in South Africa since the phased out of Pb in petroleum fuels is due to impairments of cognitive development in children [20, 39]. The presence of Fe is that the fish at these high levels poses a challenge since Fe is an essential element of human physiology hemoglobin, for instance, but may cause hemosiderosis (lung complications) [39]. The presence of Sb is a serious concern in South Africa since the Sb is a waste by-product of the manufacture of electronic circuitry and light-emitting diodes (LEDs) [63] and Sb origins maybe industrial waste or geological [64]. The Sb is not known to be essential to human health and has been associated with dermatitis, a skin disease [65], and cancer [66]. The presence of Ag is a serious concern in South Africa since the Ag may originate from the discharge of Ag-based nanoproducts in sewage effluent or in sludge [6]. Thus, there is a cause of concern since the sewage effluent continues to be discharged into these freshwater impoundments and rivers and the metal contamination of fish is likely to increase due to the detriment of rural fish consumers.

**Addo-Bediako et**

**Fish** 

**Reference** 

*O. mossambicus*

*O. mossambicus*

*C. gariepinus*

*O. mossambicus*

**species**

**dose (RfD)** 

**(μg/kg)**

**Name** 

**upstream of Oliphant** 

**Marble Hall** 

**of Oliphant Rivers**

*&* **upstream** 

**Elim**

**Elim**

**Polokwane & Seshego**

**River**

**of** 

**sewage** 

**plant**

**Name** 

**Phalaborwa barrage**

**Flag Boshielo dam**

**Albasini dam**

**Albasini dam**

**Sand River**

**of river** 

**or dam**

**Trace** 

**[Metal]** 

**Average** 

**HQ**

**[Metal]** 

**Average** 

**HQ**

**[Metal]** 

**Average** 

**HQ**

**[Metal]** 

**Average** 

**HQ**

**[Metal]** 

**Average** 

**HQ**

**(mg/kg** 

**daily** 

**dw)**

**dose** 

**(ADD)** 

**μg/kg**

**(mg/kg** 

**daily** 

**dw)**

**dose** 

**(ADD)** 

**μg/kg**

**(mg/kg** 

**daily** 

**dw)**

**dose** 

**(ADD)** 

**μg/kg**

**(mg/kg** 

**daily** 

**(mg/kg** 

**daily** 

**fw)**

**(ADD)** 

**fw)**

**dose** 

**(ADD)** 

**μg/kg**

**μg/kg**

**metals**

A1 Fe Mn Cu

Cr Ni Zn Pb Sb

V As Cd Co Ag **Table 5.**

5

1.3

0.40

0.08 0.0

0.0 Notes: Fw fresh wet: dw dry weight; aaverage dry weight of the fish; baverage of dry weight of four sample points.

The hazard quotients (HQ) for the fish species in freshwater impoundments and rivers receiving sewage effluent.

0.0 *0*

*0*

0

*0*

0

*0*

*0*

0.4

0.1

0.03

0.07 0.5

0.15

0.38 *0*

*0*

0

*0*

0

*0*

*0*

3

0.0

0.01

*0.00* 0.0

0.0

0.0 *0*

*0*

0

*0*

0

*0*

*0*

0

0

0

*0*

69

0.3

0.01

*0.00*

0.01 0.2

0.06

0.19 *0*

*0*

0

*0*

0

*0*

*0*

0

0

http://dx.doi.org/10.5772/intechopen.76565

5

53.6

0.15

0.05 7.7

2.37

0.47 0.004

*0.00*

0.00

0.005

0.005

*0.00 0*

0

*0*

0.4

0.3

0.09

0.23 5.0

1.52

3.79 *0*

*0*

0

*0*

0

*0*

*0*

0

*0*

0.057

1.2

0.37

6.14 1.0

0.31

5.12 0.003

0.00

0.015 0.003

0.003

0.015 3

0.88

14.365

300

53.6

16.4

0.05 6.4

1.97

0.01 0.202

0.06

0.00

0.243

0.07

*0.00*

131.8

38.5

0.128

20

1.2

0.38

0.02 0.5

0.15

0.01 *0*

0

0

*0*

0

*0*

0

*0*

0

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

3

3.4

1.04

0.35 9.2

2.82

0.94 *0*

*0*

0

*0*

*0.00*

*0*

*0*

*0*

*0*

40

1.2

0.37

0.01 2.6

0.81

0.02 0.003

*0.00*

*0.00*

0.012

*0.00*

*0.00 0*

*0*

*0*

140

3.8

1.17

0.01 1.3

0.4

0.0

0.012

*0.00*

*0.00*

0.021

0.01

*0.00*

206.2

60.21

0.43

700

31.4

9.61

0.01 161.7

49.49

0.07 0.241

0.07

*0.00*

0.247

0.07

*0.00*

2550

744.45

1.06

1000

14.9

4.55

*0.00* 15.0

4.58

0.0

0.813

0.24

*0.00*

0.911

0.27

*0.00 0*

*0*

*0*

 **al.** [57]

a**Nibamureke** [27]

b**Seanego** [18]

*O. mossambicus*


**4.5. Human health-risk assessment**

metal (**Table 5**).

68 Sewage

of day in between fish meals.

and the Sand River.

The consumption of fish by rural communities in South Africa is on the increase since fish is an affordable protein source in comparison with other animal or plant protein sources [60]. The fish are provided by illegal fisherman or from small-holder fish farms that are located in the Limpopo province [61, 62]. However, for wild stock fisheries, a number of studies in South Africa have shown that the popular *O. mossambicus* fish is contaminated with metals such as Al, Fe, and Pb at toxic levels [18, 27, 57, 58]. Thus, studies have been conducted to evaluate human health-risk assessment of the consumption of fish contaminated with toxic

The average daily dose (ADD) is expressed in mg/kg human body mass per day from this

*ADD* <sup>=</sup> (*average metal in fish muscle* (*fw*))*<sup>x</sup>* (*massof fish consumed*) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ (*adult body mass*)*<sup>x</sup>* (*number of days in between fish meals*) (1)

where the average metal concentration (mg/kg) in fish muscle, mass of fish consumed (kg) was 0.150 kg portion once per 7 days, adult body mass (kg) was 70 kg, and days is the number

The hazard quotient (HQ) for fish from the Albasini dam and the Sand River was calculated from the data that were provided on the trace metals in the fish muscles based on the procedure by Addo-Bediako et al. [57]. The assumptions were that an individual would eat 150 g of fish per week and the adult body mass was 70 kg as per the study by Addo-Bediako et al. [57]. The studies clearly showed the high levels of trace metals in the fish muscle, and these metals, Cr, Pb, and Sb [57] and Fe and Pb [18], were likely to affect human health (**Table 5**). The human-risk assessment (HQ) was near 1 or was above 1 and thus posed hazard to fish consumers near the Phalaborwa Barrage, Flag Boshielo dam,

The presence of Cr poses human health issues especially the Cr6+ ion which is toxic and carcinogenic to humans [39]. The presence of Pb is a serious concern in South Africa since the phased out of Pb in petroleum fuels is due to impairments of cognitive development in children [20, 39]. The presence of Fe is that the fish at these high levels poses a challenge since Fe is an essential element of human physiology hemoglobin, for instance, but may cause hemosiderosis (lung complications) [39]. The presence of Sb is a serious concern in South Africa since the Sb is a waste by-product of the manufacture of electronic circuitry and light-emitting diodes (LEDs) [63] and Sb origins maybe industrial waste or geological [64]. The Sb is not known to be essential to human health and has been associated with dermatitis, a skin disease [65], and cancer [66]. The presence of Ag is a serious concern in South Africa since the Ag may originate from the discharge of Ag-based nanoproducts in sewage effluent or in sludge [6]. Thus, there is a cause of concern since the sewage effluent continues to be discharged into these freshwater impoundments and rivers and the metal contamination of fish is likely to

expression (1) as per the procedure by Addo-Bediako et al. [57].

increase due to the detriment of rural fish consumers.

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study… http://dx.doi.org/10.5772/intechopen.76565

69

**Table 5.**

The hazard quotients (HQ) for the fish species in freshwater impoundments and rivers receiving sewage effluent.

#### **4.6. Future management strategy dealing wastewater and sludge**

The continued discharge of sewage effluent and sludge rich in trace metals is likely to continue in future as population increases in urban areas driven in part by rural to urban migration and naturally. Also, there is a need for more studies on other river catchments where there is lack of information in the Limpopo province. Other studies by Sibanda et al. [25], Shibambu [32], Gumbo et al. [68], and Olowoyo and Lion [69] have shown that the wastewater is rich in nutrients and essential traces such that the wastewater is usable for irrigation of crops, fruit trees, and vegetables. Limpopo province is a dry and arid region and the use of wastewater for irrigation is a welcome idea but there should be safeguards in place to protect the food consumers and irrigators from the negative impacts of wastewater reuse [68, 69]. The sludge may be used for innovative ways such as top soil cover (mined areas), biofertilizer, building materials, veld fire retardant and control, erosion control, forestry fertilization, and recovery of phosphorus [1]. Also, there is a need for a paradigm shift of sewage plants of just treating sewage to mining or to recover valuable and economic metals according to Mulchandani and Westerhoff [67]. The disposal of trace metals with engineered nanosized scale such as Ag, Ti, and Zn to sewage sludge is also on the increase worldwide as scientists develop and introduce new nanotechnological products. In order to safeguard the environment, there is a need to mine these trace metals from sewage sludge.

**References**

**203**:1126-1136

Research. 2017;**24**(20):17145-17152

Toxicology. 2017;**98**(5):706-711

rest goldfields, South Africa; 2017

Parys (South Africa)

Research and Public Health. 2014;**11**(3):2569-2579

Musina, South Africa (Doctoral Dissertation); 2013

Journal of African Earth Sciences. 2017;**129**:934-943

African Institute of Mining and Metallurgy. 2017;**117**(7):663-669

land application. Journal of Cleaner Production. 2018;**174**:538-547

[1] Fijalkowski K, Rorat A, Grobelak A, Kacprzak MJ. The presence of contaminations in sewage sludge–The current situation. Journal of Environmental Management. 2017;

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

http://dx.doi.org/10.5772/intechopen.76565

71

[2] Dai J, Xu M, Chen J, Yang X, Ke Z. PCDD/F, PAH and heavy metals in the sewage sludge from six wastewater treatment plants in Beijing, China. Chemosphere. 2007;**66**(2):353-361 [3] Magonono FA, Gumbo JR, Chigayo K, Dacosta FA, Mojapelo P. Bioaccumulation of toxic metals by Hyparrhenia grass species: A case study of new union gold mine tailings and Makhado town, Limpopo, South Africa. In: International Mine Water Conference 2011 [4] Zubala T, Patro M, Boguta P. Variability of zinc, copper and lead contents in sludge of the municipal stormwater treatment plant. Environmental Science and Pollution

[5] Dotaniya ML, Meena VD, Rajendiran S, Coumar MV, Saha JK, Kundu S, Patra AK. Geoaccumulation indices of heavy metals in soil and groundwater of Kanpur, India under long term irrigation of tannery effluent. Bulletin of Environmental Contamination and

[6] Shamuyarira KK, Gumbo JR. Assessment of heavy metals in municipal sewage sludge: A case study of Limpopo Province, South Africa. International Journal of Environmental

[7] Singo NK. An assessment of heavy metal pollution near an old copper mine dump in

[8] Almécija C, Cobelo-García A, Wepener V, Prego R. Platinum group elements in stream sediments of mining zones: The Hex River (Bushveld igneous complex, South Africa).

[9] Rudzani L, Gumbo JR, Yibas B, Novhe O. Geochemical and mineralogical characterization of gold mine tailings for the potential of acid mine drainage in the Sabie-Pilgrim's

[10] Maseki J, Annegarn HJ, Spiers G. Health risk posed by enriched heavy metals (As, Cd, and Cr) in airborne particles from Witwatersrand gold tailings. Journal of the Southern

[11] Yoshida H, ten Hoeve M, Christensen TH, Bruun S, Jensen LS, Scheutz C. Life cycle assessment of sewage sludge management options including long-term impacts after

[12] Mbedzi A, Gumbo JR. The release of silver and aluminium into wastewater from commercially available silver spray deodorant and soap B. Bachelor Thesis, University of Venda, Thohoyandou, South Africa. International Conference on Advances in Science, Engineering, Technology and Natural Resources (ICASETNR-16) November 24-25; 2016

#### **5. Conclusion**

The municipal sewage plants continue to discharge effluent rich in trace metals to the aquatic environment. Some of these trace metals are harmful to the humans as they biomagnify through the food web such as the consumption of fish. The introduction of nanosized metals to the sewage effluent exacerbates the situation of metal pollution of the aquatic environment. There is a need for a paradigm shift where sewage plants discharge zero effluent and start harvesting the valuable trace metals in order to protect the environment.

## **Conflict of interest**

The authors declare no conflict of interest.

#### **Author details**

Kudakwashe K. Shamuyarira and Jabulani R. Gumbo\*

\*Address all correspondence to: jabulani.gumbo@univen.ac.za

Department of Hydrology and Water Resources, University of Venda, Thohoyandou, South Africa

## **References**

**4.6. Future management strategy dealing wastewater and sludge**

to mine these trace metals from sewage sludge.

**5. Conclusion**

70 Sewage

**Conflict of interest**

**Author details**

South Africa

The authors declare no conflict of interest.

Kudakwashe K. Shamuyarira and Jabulani R. Gumbo\*

\*Address all correspondence to: jabulani.gumbo@univen.ac.za

Department of Hydrology and Water Resources, University of Venda, Thohoyandou,

The continued discharge of sewage effluent and sludge rich in trace metals is likely to continue in future as population increases in urban areas driven in part by rural to urban migration and naturally. Also, there is a need for more studies on other river catchments where there is lack of information in the Limpopo province. Other studies by Sibanda et al. [25], Shibambu [32], Gumbo et al. [68], and Olowoyo and Lion [69] have shown that the wastewater is rich in nutrients and essential traces such that the wastewater is usable for irrigation of crops, fruit trees, and vegetables. Limpopo province is a dry and arid region and the use of wastewater for irrigation is a welcome idea but there should be safeguards in place to protect the food consumers and irrigators from the negative impacts of wastewater reuse [68, 69]. The sludge may be used for innovative ways such as top soil cover (mined areas), biofertilizer, building materials, veld fire retardant and control, erosion control, forestry fertilization, and recovery of phosphorus [1]. Also, there is a need for a paradigm shift of sewage plants of just treating sewage to mining or to recover valuable and economic metals according to Mulchandani and Westerhoff [67]. The disposal of trace metals with engineered nanosized scale such as Ag, Ti, and Zn to sewage sludge is also on the increase worldwide as scientists develop and introduce new nanotechnological products. In order to safeguard the environment, there is a need

The municipal sewage plants continue to discharge effluent rich in trace metals to the aquatic environment. Some of these trace metals are harmful to the humans as they biomagnify through the food web such as the consumption of fish. The introduction of nanosized metals to the sewage effluent exacerbates the situation of metal pollution of the aquatic environment. There is a need for a paradigm shift where sewage plants discharge zero effluent and start

harvesting the valuable trace metals in order to protect the environment.


[13] Wu L, Yang L, Wang Z, Cheng M, Li Z, Liu W, Ma T, Christie P, Luo Y. Uptake of silver by brown rice and wheat in soils repeatedly amended with biosolids. Science of the Total Environment. 2018;**612**:94-102

Africa. In: 12th International Conference on Modelling, Monitoring and Management of

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

http://dx.doi.org/10.5772/intechopen.76565

73

[27] Nibamureke MCU. Fish histopathology as a tool to assess the health status of freshwater fish species in Albasini Dam, Limpopo Province, South Africa. Unpublished MSc. University of Johannesburg; 2015. Retrieved from https://ujdigispace.uj.ac.za [Accessed:

[28] Edokpayi JN, Odiyo JO, Popoola OE, Msagati TA. Assessment of trace metals contamination of surface water and sediment: A case study of Mvudi River, South Africa.

[29] Edokpayi JN, Odiyo JO, Msagati TA, Popoola EO. Removal efficiency of Faecal indicator organisms, nutrients and heavy metals from a Peri-urban wastewater treatment plant in Thohoyandou, Limpopo Province, South Africa. International Journal of Environmental

[30] DWAF. South African Water Quality Guidelines, Aquatic Ecosystems. Vol. 7. Pretoria:

[32] Shibambu, CS. An assessment of water quality of the wetland downstream of Makhado Oxidation Pond and its potential effects on irrigation waters. Unpublished Masters" dis-

[33] Hussain B, Sultana T, Sultana S, Al-Ghanim KA, Masood S, Ali M, Mahboob S. Microelectrophoretic study of environmentally induced DNA damage in fish and its use for early toxicity screening of freshwater bodies. Environmental Monitoring and

[34] Aigle A, Bonin P, Iobbi-Nivol C, Méjean V, Michotey V. Physiological and transcriptional approaches reveal connection between nitrogen and manganese cycles in Shewanella

[35] Quintero MP, Milán ÁG, Pérez JG, Arroyo JM, Gil MC, Mariño MM. Hyperthermia: Acute effect on copper and iron trace minerals in erythrocytes, serum and urine.

[36] Wijnhoven SW, Peijnenburg WJ, Herberts CA, Hagens WI, Oomen AG, Heugens EH, Roszek B, Bisschops J, Gosens I, Van De Meent DI, Dekkers S. Nano-silver–A review of available data and knowledge gaps in human and environmental risk assessment.

[37] Shukla M, Arya S. Cadmium toxicity induced morphological alteration in indigenous fish *Heteropneustes fossilis* (Bloch.). Green Chemistry & Technology Letters. 2017;**3**(1):21-25

[38] Martín-Folgar R, Martínez-Guitarte JL. Cadmium alters the expression of small heat shock protein genes in the aquatic midge Chironomus riparius. Chemosphere. 2017;

Water Pollution; 2014

January 16, 2018]

DWAF; 1996

Sustainability. 2016;**8**(2):135

Research and Public Health. 2015;**12**(7):7300-7320

[31] CCME. Canadian Environmental Quality Guidelines; 2012

sertation, University of Venda; 2016

algae C6G3. Scientific Reports. 2017;**7**:44725

Assessment. 2017;**189**(3):115

Motricidade. 2017;**13**(1):180

**169**:485-492

Nanotoxicology. 2009;**3**(2):109-138


Africa. In: 12th International Conference on Modelling, Monitoring and Management of Water Pollution; 2014


[13] Wu L, Yang L, Wang Z, Cheng M, Li Z, Liu W, Ma T, Christie P, Luo Y. Uptake of silver by brown rice and wheat in soils repeatedly amended with biosolids. Science of the Total

[14] Statistics South Africa. Gross domestic product: Annual estimates 2002-2010, Regional estimates 2002-2010, Third quarter 2011 (PDF) (Report). November 29, 2011. p. 31. Retrieved

[15] Gessellen van A. The presence of persistent organic pollutants and heavy metals in sediment samples from rivers in the Kruger National Park. Unpublished Masters" disserta-

[17] Greenfield R, Van Vuren JH, Wepener V. Heavy metal concentrations in the water of the Nyl River system, South Africa. African Journal of Aquatic Science. 2012;**37**(2):219-224 [18] Seanego KG. Ecological status of the Sand River after the discharge of sewage effluent from the Polokwane and Seshego wastewater treatment works. Unpublished Masters"

[19] Edokpayi JN, Odiyo JO, Olasoji SO. Assessment of heavy metal contamination of Dzindi River, in Limpopo Province, South Africa. International Journal of Natural Sciences

[20] Gumbo JR, Dzaga RA, Nethengwe NS. Impact on water quality of Nandoni water reservoir downstream of municipal sewage plants in Vhembe District, South Africa.

[21] Edokpayi JN, Odiyo JO, Popoola EO, Msagati TA. Evaluation of temporary seasonal variation of heavy metals and their potential ecological risk in Nzhelele River, South

[22] Shibambu C, Gumbo J, Gitari W. Field study on heavy metal removal in a natural wetland receiving municipal sewage discharge. International Journal of Sustainable

[23] Dabrowski J, Oberholster PJ, Dabrowski JM. Water quality of flag Boshielo dam, Olifants River, South Africa: Historical trends and the impact of drought. Water SA.

[24] Edokpayi JN, Odiyo JO, Shikwambana PP. Seasonal variation of the impact of mining activities on Ga-Selati River in Limpopo Province, South Africa. World Academy of Science, Engineering and Technology, International Journal of Environmental, Chemical,

[25] Sibanda T, Selvarajan R, Tekere M. Urban effluent discharges as causes of public and environmental health concerns in South Africa's aquatic milieu. Environmental Science

[26] Baloyi C, Gumbo JR, Muzerengi C. Pollutants in sewage effluent and sludge and its impact on downstream water quality: A case study of Malamulele sewage plant, South

Ecological, Geological and Geophysical Engineering. 2016;**10**(2):156-161

Environment. 2018;**612**:94-102

tion, North West University; 2015

dissertation, University of Limpopo; 2014

[16] DWA. Green Drop Report of 2013

Research. 2014;**2**(10):185-194

Sustainability. 2016;**8**(7):597

2014;**40**(2):345-358

Africa. Open Chemistry;**15**(1):272-282

Development and Planning. 2017;**12**(1):1-10

and Pollution Research. 2015;**22**(23):18301-18317

February 24, 2018

72 Sewage


[39] Lajçi N, Sadiku M, Lajçi X, Baruti B, Nikshiq S. Assessment of major and trace elements of fresh water springs in village Pepaj, Rugova region, Kosova. Journal International Environmental Application & Science. 2017;**12**(2):112-120

[53] Xie Y, Lu G, Yang C, Qu L, Chen M, Guo C, Dang Z. Mineralogical characteristics of sediments and heavy metal mobilization along a river watershed affected by acid mine

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study…

http://dx.doi.org/10.5772/intechopen.76565

75

[54] Taiwo AM, Olujimi OO, Bamgbose O, Arowolo TA. Surface water quality monitoring in Nigeria: Situational analysis and future management strategy. In: Water Quality

[55] Dahms S, Baker NJ, Greenfield R. Ecological risk assessment of trace elements in sediment: A case study from Limpopo, South Africa. Ecotoxicology and Environmental

[56] Australian and New Zealand Environmental and Conservation Council (ANZECC). The Guidelines. Vol. 12000 www.agriculture.gov.au/SiteCollectionDocuments/water/

[57] Addo-Bediako A, Marr SM, Jooste A, Luus-Powell WJ. Are metals in the muscle tissue of Mozambique tilapia a threat to human health? A case study of two impoundments in the Olifants River, Limpopo province, South Africa. Annales de Limnologie-International

[58] Oberholster PJ, Myburgh JG, Ashton PJ, Coetzee JJ, Botha AM. Bioaccumulation of aluminium and iron in the food chain of Lake Loskop, South Africa. Ecotoxicology and

[59] Magonono M. A comparative study of the origins of cyanobacteria at musina water treatment plant using DNA finger print unpublished masters dissertation. University

[60] McCafferty JR, Ellender BR, Weyl OL, Britz PJ. The use of water resources for inland

[61] Addo-Bediako A, Marr SM, Jooste A, Luus-Powell WJ. Human health risk assessment for silver catfish Schilbe intermedius Rüppell, 1832, from two impoundments in the

[62] Tshifura A. An assessment of Algae species and their cyanotoxins in small holder aquaculture production systems: A case study of Vhembe district, South Africa unpublished

[63] Yang JL. Comparative acute toxicity of gallium (III), antimony (III), indium (III), cadmium (II), and copper (II) on freshwater swamp shrimp (Macrobrachium nipponense).

[64] Ahmed MK, Baki MA, Islam MS, Kundu GK, Habibullah-Al-Mamun M, Sarkar SK, Hossain MM. Human health risk assessment of heavy metals in tropical fish and shellfish collected from the river Buriganga, Bangladesh. Environmental Science and

[65] Reilly C. Metal Contamination of Food: Its Significance for Food Quality and Human

Olifants River, Limpopo, South Africa. Water SA. 2014;**40**(4):607-614

drainage. PLoS One. 2018;**13**(1):e0190010

Safety. 2017;**135**:106-114

nwqms-guidelines-4-vol1.pdf

Environmental Safety. 2012;**75**:134-141

of Venda; 2017

Monitoring and Assessment. Rijeka, Croatia: InTech; 2012

Journal of Limnology. 2014;**50**(3):201-210 EDP Sciences

fisheries in South Africa. Water SA. 2012;**38**(2):327-344

masters dissertation. University of Venda; 2018

Pollution Research. 2015;**22**(20):15880-15890

Health. New York: John Wiley & Sons; 2008

Biological Research. 2014;**47**(1):13


[53] Xie Y, Lu G, Yang C, Qu L, Chen M, Guo C, Dang Z. Mineralogical characteristics of sediments and heavy metal mobilization along a river watershed affected by acid mine drainage. PLoS One. 2018;**13**(1):e0190010

[39] Lajçi N, Sadiku M, Lajçi X, Baruti B, Nikshiq S. Assessment of major and trace elements of fresh water springs in village Pepaj, Rugova region, Kosova. Journal International

[40] DWAF. Guidelines for the utilisation and disposal of wastewater sludge. Vol. 4. 2008. http:www.dwaf.gov,za/Dir\_WQM/docs/wastewatersludgeMar08vol4part1.pdf

[41] Shamuyarira, KK. Assessment of heavy metals in municipal sewage sludge: A case study of Limpopo Province, South Africa. Unpublished Hons" dissertation, University

[42] Watanabe CH, Monteiro AS, Gontijo ES, Lira VS, de Castro BC, Kumar NT, Fracácio R, Rosa AH. Toxicity assessment of arsenic and cobalt in the presence of aquatic humic substances of different molecular sizes. Ecotoxicology and Environmental Safety. 2017;

[43] Iglesias M, Marguí E, Camps F, Hidalgo M. Extractability and crop transfer of potentially toxic elements from mediterranean agricultural soils following long-term sewage sludge applications as a fertilizer replacement to barley and maize crops. Waste Management.

[44] Ogbazghi ZM, Tesfamariam EH, Annandale JG, De Jager PC, Mbakwe I. Mobility and uptake of Zn, Cd, Ni and Pb in sludge-amended soils planted to dryland maize and irri-

[45] Mackevica A, Olsson ME, Hansen SF. The release of silver nanoparticles from commer-

[46] Benn TM, Westerhoff P. Nanoparticle silver released into water from commercially available sock fabrics. Environmental Science & Technology. 2008;**42**(11):4133-4139 [47] Kim B, Park CS, Murayama M, Hochella MF Jr. Discovery and characterization of silver sulfide nanoparticles in final sewage sludge products. Environmental Science &

[48] Snyman HG ,Herselman JE. Guidelines for the utilisation and disposal of wastewater sludge. WRC report No. TT 261/06, March 2006, Pretoria, South Africa; 2006

[49] Monica J. Final federal register notice EPA decided not to regulate products containing nanosilver; 2007. www.nanolawreport.com/2007/09/articles/epa-finally-issues-nanosil-

[50] EC. Commission Regulation (EC) No 1451/2007. C.O.E. Communities, Official Journal of

[51] Modika L.Assessment of nanosilver particles released into water from commercially available deodorants [Honour's thesis]. Thohoyandou: University of Venda; 2012 [52] Osman NA, Zaki A, Agamy NF, Shehata GM. Aluminum in food: Dietary exposure among adolescent residents in the food catering establishments in Alexandria, Egypt.

Global Journal of Pharmaceutical Education and Research. 2018;**6**:1-6

gated maize-oat rotation. Journal of Environmental Quality. 2015;**44**(2):655-657

cial toothbrushes. Journal of Hazardous Materials. 2017;**322**:270-275

Environmental Application & Science. 2017;**12**(2):112-120

[Accessed: December 30, 2013]

of Venda; 2013

2018;**75**:312-318

Technology. 2010;**44**(19):7509-7514

the European Union. 2007:3-65

ver-notice. [Accessed: December 30, 2013]

**139**:1-8

74 Sewage


[66] Govind P, Madhuri S. Heavy metals causing toxicity in animals and fishes. Research Journal of Animal, Veterinary and Fishery Sciences. 2014;**2**(2):17-23

**Chapter 5**

**Provisional chapter**

**Fate of Radiopharmaceuticals in the Environment**

**Fate of Radiopharmaceuticals in the Environment**

DOI: 10.5772/intechopen.74665

After World War II, the use of artificially produced radionuclides in medicine began and led to great success in the fight against cancer and other diseases. However, the highly radioactive compounds had to be handled with great care to protect patients and hospital personnel from radiation. The survey of these radionuclides in the environment followed some years later. In Switzerland, double-tracked monitoring programs were started. On the emission side, hospitals and industries handling radiopharmaceuticals had to report their consummation of radionuclides yearly. A monitoring program of their waste waters and solid wastes was also started. On the immission side, the remaining radioactive wastes, which were released to the environment, had to be surveyed. Overall, only a few violations of the limits for radiopharmaceuticals were observed over the last 30 years in Switzerland. Nevertheless, the monitoring of radioactivity in the environment

remains an important task as long as radionuclides are used in medicine.

**Keywords:** radiopharmaceuticals, y-90, Lu-177, I-131, sewage sludge, sewer sludge,

Radiopharmaceuticals were first synthesised back in 1933. In Paris, Irène and Frédéric Joliot-Curie produced the first synthetic radionuclide by irradiating aluminium foil with alpha particles. They obtained a radioactive phosphor nuclide (<sup>30</sup>P). The irradiation of boron resulted in a radioactive nitrogen nuclide [1]. Soon after their discovery of synthetic radionuclides, first applications were published (e.g., studies of metabolism with radioactive tracers and the use of radionuclides in diagnosis and therapy started). After World War II, the nuclear pharmacy industry started in USA. In the 1960s, a group of scientists founded the "radiological chemistry" at the University of Basel. Their focus was on the synthesis and applications of

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

Markus R. Zehringer

Markus R. Zehringer

**Abstract**

suspended matter

**1. Introduction**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.74665


#### **Fate of Radiopharmaceuticals in the Environment Fate of Radiopharmaceuticals in the Environment**

DOI: 10.5772/intechopen.74665

#### Markus R. Zehringer Markus R. Zehringer

[66] Govind P, Madhuri S. Heavy metals causing toxicity in animals and fishes. Research

[67] Mulchandani A, Westerhoff P. Recovery opportunities for metals and energy from sew-

[68] Gumbo JR, Malaka EM, Odiyo JO, Nare L. The health implications of wastewater reuse in vegetable irrigation: A case study from Malamulele, South Africa. International

[69] Olowoyo JO, Lion GN. Urban farming as a possible source of trace metals in human

Journal of Animal, Veterinary and Fishery Sciences. 2014;**2**(2):17-23

age sludges. Bioresource Technology. 2016;**215**:215-226

76 Sewage

Journal of Environmental Health Research. 2010;**20**(2):1-11

diets. South African Journal of Science. 2016;**112**(1-2):01-06

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.74665

**Abstract**

After World War II, the use of artificially produced radionuclides in medicine began and led to great success in the fight against cancer and other diseases. However, the highly radioactive compounds had to be handled with great care to protect patients and hospital personnel from radiation. The survey of these radionuclides in the environment followed some years later. In Switzerland, double-tracked monitoring programs were started. On the emission side, hospitals and industries handling radiopharmaceuticals had to report their consummation of radionuclides yearly. A monitoring program of their waste waters and solid wastes was also started. On the immission side, the remaining radioactive wastes, which were released to the environment, had to be surveyed. Overall, only a few violations of the limits for radiopharmaceuticals were observed over the last 30 years in Switzerland. Nevertheless, the monitoring of radioactivity in the environment remains an important task as long as radionuclides are used in medicine.

**Keywords:** radiopharmaceuticals, y-90, Lu-177, I-131, sewage sludge, sewer sludge, suspended matter

#### **1. Introduction**

Radiopharmaceuticals were first synthesised back in 1933. In Paris, Irène and Frédéric Joliot-Curie produced the first synthetic radionuclide by irradiating aluminium foil with alpha particles. They obtained a radioactive phosphor nuclide (<sup>30</sup>P). The irradiation of boron resulted in a radioactive nitrogen nuclide [1]. Soon after their discovery of synthetic radionuclides, first applications were published (e.g., studies of metabolism with radioactive tracers and the use of radionuclides in diagnosis and therapy started). After World War II, the nuclear pharmacy industry started in USA. In the 1960s, a group of scientists founded the "radiological chemistry" at the University of Basel. Their focus was on the synthesis and applications of

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

protein-bound radionuclides. They were the first to develop DOTATOC1 -bound 111In and 90Y and apply them with success against tumours.

Today, 33 Swiss hospitals use radionuclides. Twenty-three of these hospitals discharge their contaminated waste waters to WWTPs, which are connected to the Rhine/Aar River system. **Table 1** lists the most used radionuclides in Switzerland and the percentage of their use in

As can be observed, the Basel University Hospital is highly specialised in applications of 90Y and 177Lu. Only a few GBq of 177Lu are applied in hospital centres at Bern, St. Gallen, Lausanne and Zurich. 90Y is used in many hospitals, but in remarkably lower activities than in Basel. **Figure 1** shows consumption of radionuclides of radionuclides over the last 18 years. The consumption of 131I is almost stable between 300 and 500 GBq/year. 90Y shows a maximum in 2009 (2500 GBq/year); its use has been reduced since 2009 to almost 1000 GBq/year. Applications of

**Switzerland Hospitals in Basel City Percentage of Basel City**

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 79

Basel compared to the whole Switzerland [3].

**Table 1.** Applied radionuclides in Switzerland 2016, in GBq.

131I ambulant appl. 25.2 0 0 131I hospitalised appl. 2.593 221 9 <sup>186</sup>Re 2.3 0.4 16 169Er 1.0 0 0 <sup>90</sup>Y 1.099 568 52 153Sm 4.0 0 0 177Lu 3.040 2.608 86 223Ra 4.1 0.2 3

Data from [2]. appl: applications for ambulatory or hospitalised patients; LE: exemption limit.

**Figure 1.** Yearly consumed activities of radiopharmaceuticals at Basel hospitals since 1998.

#### **1.1. Application of radiopharmaceuticals**


Specific radionuclides used in therapeutical applications include the following:

131I (iodine-131), a thyreostatica which is administered in the form of swallowable 131I–capsules, is used to treat diseases of the thyrea (hyperthyroidism and Basedow's disease). In Switzerland, 200 MBq may be applied for ambulatory treated patients. For higher activities, patients have to stay at specially isolated rooms, until the required dose becomes less than 5 μSv/h at a distance of 1 m. 131I is also applied bound with MIBG (metaiodobenzyl-guanidine).


#### **1.2. Use of radiopharmaceuticals in Basel and Switzerland**

The Federal Office for Public Health, Radioprotection Section, publishes annually the consumption of radionuclides and radiopharmaceuticals by industry and hospitals together with data from the radioactivity monitoring of the effluents of waste water treatment plants (WWTP) and other emission sources in Switzerland [2].

<sup>1</sup> DOTATOC: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate coupled with an octapeptide.

<sup>2</sup> An application of radiopharmaceuticals to fight arthritis and arthrosis.

Today, 33 Swiss hospitals use radionuclides. Twenty-three of these hospitals discharge their contaminated waste waters to WWTPs, which are connected to the Rhine/Aar River system. **Table 1** lists the most used radionuclides in Switzerland and the percentage of their use in Basel compared to the whole Switzerland [3].

As can be observed, the Basel University Hospital is highly specialised in applications of 90Y and 177Lu. Only a few GBq of 177Lu are applied in hospital centres at Bern, St. Gallen, Lausanne and Zurich. 90Y is used in many hospitals, but in remarkably lower activities than in Basel. **Figure 1** shows consumption of radionuclides of radionuclides over the last 18 years. The consumption of 131I is almost stable between 300 and 500 GBq/year. 90Y shows a maximum in 2009 (2500 GBq/year); its use has been reduced since 2009 to almost 1000 GBq/year. Applications of


Data from [2]. appl: applications for ambulatory or hospitalised patients; LE: exemption limit.

**Table 1.** Applied radionuclides in Switzerland 2016, in GBq.

protein-bound radionuclides. They were the first to develop DOTATOC1

**i.** Today, a broad range of radiopharmaceuticals are used for diagnostics and the fight against cancer and other diseases. Radionuclides are either used in their pure form (e.g.,

sion tomography (PET), single photon emission computed tomography (SPECT) and others. Specific radionuclides that are in use include the following:99mTc (technetium-99m), which is used for the scintigraphy of the skeleton, heart, lung, brain, liver, kidney, marrow

**ii.** For the detection of neuroendocrine tumours, 111In (indium-111) and 68Ga (gallium-68)

**iii.** For the diagnosis of prostate tumours, brain tumours and metastases in bones, 18F (fluo-

131I (iodine-131), a thyreostatica which is administered in the form of swallowable 131I–capsules, is used to treat diseases of the thyrea (hyperthyroidism and Basedow's disease). In Switzerland, 200 MBq may be applied for ambulatory treated patients. For higher activities, patients have to stay at specially isolated rooms, until the required dose becomes less than 5 μSv/h at a distance of 1 m. 131I is also applied bound with MIBG (metaiodobenzyl-guanidine).

**i.** 90Y (yttrium-90) and 177Lu (lutetium-177) are applied successfully against neuroendocrine tumours. These radionuclides are bound to DOTATOC, an octapeptide, which has a similar structure as the hormone somatostatin. 90Y is applied in selective, internal radiothera-

**iii.** Other radionuclides, such as 90Y, 188Re (rhenium-188), 169Er (erbium-169), are applied for

**iv.** A recently available radionuclide is <sup>223</sup>Ra (radium-223). In the form of radium dichloride, Xofigo, it can be used against prostate tumours that have spread to the skeleton. In Basel,

The Federal Office for Public Health, Radioprotection Section, publishes annually the consumption of radionuclides and radiopharmaceuticals by industry and hospitals together with data from the radioactivity monitoring of the effluents of waste water treatment plants

etc. It is also used in techniques, such as myocardia- and parotid scintigraphy.

rine-18) is commonly used as the radionuclide in scintigraphy.

py (SIRT) bound on spherical polymer particles.

.

**1.2. Use of radiopharmaceuticals in Basel and Switzerland**

(WWTP) and other emission sources in Switzerland [2].

An application of radiopharmaceuticals to fight arthritis and arthrosis.

DOTATOC: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate coupled with an octapeptide.

**ii.** 90Y–Zevalin is used against lymphoma.

it has been administered since 2013.

radiation synovectomy<sup>2</sup>

1

2

Specific radionuclides used in therapeutical applications include the following:

) or bound on a carrier. For diagnosis, they are used in scintigraphy, positron emis-

and apply them with success against tumours.

**1.1. Application of radiopharmaceuticals**

223RaCl2

78 Sewage

can be used.


**Figure 1.** Yearly consumed activities of radiopharmaceuticals at Basel hospitals since 1998.

177Lu started in 2002 and started to rise over the years to 3000 GBq/year in 2016. In that year, the hospitals of Basel used overall 4.5 TBq activity. In Basel, more than 8000 persons per year were treated with radiopharmaceuticals for diagnosis and therapies against cancer and for other applications [4].

2 of the RPO, solid and liquid wastes may not reach activities higher than a permitted limit

a<sup>1</sup> /EL1 + a2 /EL<sup>2</sup> + …+ An/ELn < 0.01 (1)

The sum in Eq. (1) has to be below 0.01; then, the activity of the waste water is under the limit value. Further, a specific discharge limit per month for treated and untreated waste water has to be fulfilled. A violation is present when both limits are overridden. The aim of these restrictions is to guarantee a limit value of 1/50 of EL for each radionuclide in rivers and lakes (according to Art.102. Par. 2 of the RPO). The Federal Office of Public Health uses the same

The whole waste water of the city of Basel is treated at the *WWTP Pro Rheno*. In this plant, the waste water (A) is treated in three main steps (see **Figure 2**): First solids are taken out by a coarse screen (3). Yearly, 370 tonnes of solid wastes are extracted in that way and burnt at the incineration station *KVA Basel* (a) [7]. Then, the waste water runs through degritters (4). The filtered off solid materials are disposed at a nearby landfill site (b). The pre-cleaned waste water undergoes a preliminary cleaning with a primary clarification step (5). Then follows a biological treatment of

EL: exemption limit. The ingestion of 1 kg of a radionuclide with a specific activity of 1 EL yields a committed effective

**Figure 2.** Scheme of the municipal WWTP of the city of Basel, *ProRheno* (source: *ProRheno* AG (with the kind permission

limits for treated waste waters that are discharged to rivers and lakes (**Table 2**).

**3.1. The waste water treatment: The municipal WWTP of Basel**

: exemption limit of radionuclide x.

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 81

Mixtures of radionuclides are considered as follows (summation rule):

with axe: activity of radionuclide x, ELx

**3. The waste treatment in Basel City**

). For higher activities, the material has to be treated as "radioactive" according to the Ordinance. For waste water, the activity limit is set to 1% of the EL of each radionuclide.

(EL<sup>3</sup>

3

dose of 10 μSv [6].

of *ProRheno AG* [7]). Details explained in the text.

Waste water and other wastes of patients are collected in special stainless steel tanks, while the patients are hospitalised. Due to their short half-lives, the activity of the radionuclides declines very fast. Cooling time in the storage tanks is several weeks. Once a week, tanks are discharged into the waste net when the activity of the radionuclides falls below a specified activity level. This level is fixed in such a way that the limit values for rivers cannot be reached.

#### **2. Legislation in Switzerland**

Since 1991, in Switzerland, radionuclides are regulated by the Radioprotection Act (from 22 March 1991) [5] and the Radioprotection Ordinance (RPO) (from 22 June 1994) [6]. In Annex


Source: Swiss Radioprotection Ordinance [6].

1 About 1% of the exemption limit (LE).

2 About 100 fold of LE for waste water.

3 About 1/50 of LE for rivers and lakes.

**Table 2.** Limits for radionuclides used in medicine.

2 of the RPO, solid and liquid wastes may not reach activities higher than a permitted limit (EL<sup>3</sup> ). For higher activities, the material has to be treated as "radioactive" according to the Ordinance. For waste water, the activity limit is set to 1% of the EL of each radionuclide. Mixtures of radionuclides are considered as follows (summation rule):

$$\mathbf{a}\_1/\text{EL}\_1 + \mathbf{a}\_2/\text{EL}\_2 + ... + \mathbf{A}\_n/\text{EL}\_n \le 0.01\tag{1}$$

with axe: activity of radionuclide x, ELx : exemption limit of radionuclide x.

The sum in Eq. (1) has to be below 0.01; then, the activity of the waste water is under the limit value. Further, a specific discharge limit per month for treated and untreated waste water has to be fulfilled. A violation is present when both limits are overridden. The aim of these restrictions is to guarantee a limit value of 1/50 of EL for each radionuclide in rivers and lakes (according to Art.102. Par. 2 of the RPO). The Federal Office of Public Health uses the same limits for treated waste waters that are discharged to rivers and lakes (**Table 2**).

#### **3. The waste treatment in Basel City**

177Lu started in 2002 and started to rise over the years to 3000 GBq/year in 2016. In that year, the hospitals of Basel used overall 4.5 TBq activity. In Basel, more than 8000 persons per year were treated with radiopharmaceuticals for diagnosis and therapies against cancer and for

Waste water and other wastes of patients are collected in special stainless steel tanks, while the patients are hospitalised. Due to their short half-lives, the activity of the radionuclides declines very fast. Cooling time in the storage tanks is several weeks. Once a week, tanks are discharged into the waste net when the activity of the radionuclides falls below a specified activity level. This level is fixed in such a way that the limit values for rivers cannot be reached.

Since 1991, in Switzerland, radionuclides are regulated by the Radioprotection Act (from 22 March 1991) [5] and the Radioprotection Ordinance (RPO) (from 22 June 1994) [6]. In Annex

> **Activity limit (Bq/kg)1**

, γ 30.000 300 3.000 600

, γ 100.000 1.000 10.000 2.000

, γ 4.000 40 400 80

, γ 500 5 50 10

, γ 2.000 20 200 40

, γ 10.000 100 1.000 200

, γ 30.000 300 3.000 600

, γ 20.000 200 2.000 400

, γ 6.000 60 600 120

, γ 7.000 70 700 140

, γ 7.000 70 700 140

**Activity load per month2 (kBq)**

**Limit value for surface** 

**water3 (Bq/kg)**

**Bq/kg**

18F 109.8 m β<sup>+</sup> 200.000 2.000 20.000 4.000

<sup>67</sup>Ga 78.3 h γ 50.000 500 5.000 1.000

85Sr 65 d γ 20.000 200 2.000 400 <sup>90</sup>Y 64 h β− 4.000 40 400 80 99mTc 60.2 h γ 500.000 5′000 50.000 10.000

111In 2.83 d γ 30.000 300 3.000 600

223Ra 11.4 α, γ 100 1 10 2

other applications [4].

80 Sewage

**2. Legislation in Switzerland**

**Radionuclide Half-life decay LE**

44Sc 3.93 h β<sup>+</sup>

<sup>68</sup>Ga 68 m β<sup>+</sup>

110mAg 249.9 d β−

<sup>131</sup>I 8.04 d β−

<sup>133</sup>I 20.8 h β−

153Sm 46.7 h β−

169Er 9.3 d β−

177Lu 6.71 d β−

177mLu 160.9 d β−

<sup>186</sup>Re 90.6 h β−

<sup>188</sup>Re 17.0 h β−

1

2

3

Source: Swiss Radioprotection Ordinance [6].

**Table 2.** Limits for radionuclides used in medicine.

About 1% of the exemption limit (LE).

About 100 fold of LE for waste water.

About 1/50 of LE for rivers and lakes.

#### **3.1. The waste water treatment: The municipal WWTP of Basel**

The whole waste water of the city of Basel is treated at the *WWTP Pro Rheno*. In this plant, the waste water (A) is treated in three main steps (see **Figure 2**): First solids are taken out by a coarse screen (3). Yearly, 370 tonnes of solid wastes are extracted in that way and burnt at the incineration station *KVA Basel* (a) [7]. Then, the waste water runs through degritters (4). The filtered off solid materials are disposed at a nearby landfill site (b). The pre-cleaned waste water undergoes a preliminary cleaning with a primary clarification step (5). Then follows a biological treatment of

**Figure 2.** Scheme of the municipal WWTP of the city of Basel, *ProRheno* (source: *ProRheno* AG (with the kind permission of *ProRheno AG* [7]). Details explained in the text.

<sup>3</sup> EL: exemption limit. The ingestion of 1 kg of a radionuclide with a specific activity of 1 EL yields a committed effective dose of 10 μSv [6].

the waste water with activated sludge and oxygen, where most organic substances are degraded (7). The produced sewage sludge is isolated by sedimentation. At last, the waste water undergoes a secondary clarifying step (8). Over 90% of the organic carbon is degradable. Phosphates, which are the most important nutrient for algae, are eliminated by chemical precipitation. Nitrogen is not eliminated (e.g., by a nitrification/denitrification process). The so treated waste water is then released to the Rhine River below the city of Basel, near the border to Germany and France (B). The isolated sewage sludge is centrifuged (c, d). This thickened sludge is then burnt in fluidized bed furnaces (9). The ashes are disposed at a nearby landfill site (**Figure 2**).

consumption of radiopharmaceuticals and the discharge of total activity in 131I–equivalents to the rivers). Several Swiss WWTPs and waste incineration plants, which are in the catchment area of hospitals, chemical radionuclide producing industries and watch industries are moni-

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 83

For balancing radionuclides in waste water, a permanent sampling is necessary. This is only possible by using automatic water samplers. At the WWTP *ProRheno*, several samplers continuously collect water samples at several locations. Most important is the sampling of the untreated, raw waste water, before it enters the WWTP, and the treated waste water, before it is discharged to the Rhine River. The sampling rate of the samplers is fixed by the continuously recorded water flow rate. At higher rates, more water is sampled. Other samplers are necessary to control and optimise the waste water treatment processes inside the WWTP. At the waste incineration of Basel *KVA Basel*, the treated waste water from wet scrubbing of the flue gases is sampled permanently over 24 hours a day. This sampling is not operated by the water flow rate. The monitoring programmes of WWTP *ProRheno* and the waste incineration plant *KVA Basel* are based on water samples, which are representative for the whole time period (24 hours or a week). The water samples are delivered once a week to the State Laboratory of Basel City. The cleaned waste water from WWTP *ProRheno* consists of a 1 L sample, which was sampled over a whole week. The cleaned waste water contains a small amount of insoluble material (20–40 mg/L). The water samples from *KVA Basel* are daily samples, which are mixed in the laboratory to get a week sample. These samples are free from insoluble materials. The water samples are filled into 1 L

For the balancing experiments at WWTP *ProRheno*, sewage sludge and ash samples have to be analysed. These samples are filled into cylindrical beakers of 500 mL volume or, where possible, into 1 L Marinelli beakers. Sewer samples (sewer sludge or sewer slime) are collected in the waste net of the city of Basel. The sewer is filled into petri dishes (6.5 cm Ø). Considering the short half-lives of the radionuclides of interest (e.g., 99mTc), the gamma ray counting has to be started immediately after having received the samples. All solid samples were counted without drying to take into account the short half-life of some radionuclides and the volatility of certain radionuclides (e.g., 131I). Afterwards, all solid samples were dried at 110°C. All

In 1980–2012, suspended matter of the Rhine River was collected in 50 L barrels in three months periods upstream of the city of Basel. The suspended matter was then co-precipitated with potassium zinc hexacyanoferrate-(II), clarified using Carrez solutions, dried and analysed with gamma ray spectrometry. After 2002, the suspended matter from Rhine River was sampled once a month at the *International Monitoring Station (Rüs) at Weil am Rhein*, Germany, near Basel. To filter off the suspended matter from the water, a centrifuge was continuously loaded with Rhine water. This water was a mixture of the Rhine water over the whole profile of the river. Depending on the water flow, the sampling time took one to several days.

tored continuously. Yearly, the BAG publishes the data [2].

Marinelli beakers for gamma ray spectrometry.

activities were calculated back to a dry-weight basis.

**4.2. Sampling**

*4.2.1. Water samples*

*4.2.2. Solid samples*

A total of 270,000 inhabitants of Basel City and surrounding villages (several villages of France and Germany included) release their waste waters to the waste net of the city, which has a length of about 360 km. It ends at the WWTP in the north of the city. The WWTP treats 82,000 m<sup>3</sup> of waste water a day; 30 million m<sup>3</sup> waste water a year, respectively. About 40% of the waste water originates from households (170 L of water are used per person per day). Special waste waters are discharged by the hospitals and industries. Waste waters from chemical industries in Basel are treated in a separate, independent WWTP, especially built for the treatment of chemical waste waters. For more details about the WWTP, visit the website of *ProRheno* [8].

#### **3.2. The solid waste treatment at Basel: The municipal waste incineration plant of Basel**

The waste incineration plant *KVA Basel* has a capacity of 230,000 tonnes/year for burning wastes from households and permitted wastes from industries (that means 103 tonnes a day) [9]. Only 29% of the wastes are from the city of Basel. About 54% of the wastes are delivered from the state of Basel-Campaign and other Swiss states. The German Landkreis Lörrach delivers another 17%. The wastes originate from about 700,000 persons. They are burnt in two oven lines, which produce 537 GWh/year of heating energy (the value for energy consumption is 76%). The fire gases are cleaned in several steps: dust is eliminated by electrofilters. Nitrogen oxides are neutralised with ammonia. To destroy toxic dioxins and furans, special catalysts are used. The pre-cleaned air then undergoes a wet scrubbing with water. This waste water is treated on site with the incinerator's own treatment plant. The chemical quality of the cleaned water (about 190 m<sup>3</sup> /d) satisfies the quality criteria for treated waste water and can therefore be discharged directly to the Rhine River. The ashes are cooled down with water and stored in bunkers. About 43,800 tonnes of ashes are disposed of at a nearby landfill site. For more information, see [10].

## **4. Materials and methods**

#### **4.1. Swiss monitoring programme**

Since 1956, environmental radioactivity has been continuously monitored in Switzerland. The motivation for the programme was the occurrence of the global fallout from bomb tests. Since 1986, the Federal Office of Public Health (BAG) is authorized to survey the ionising radiation and radioactivity in the environment. It has to organise a yearly monitoring programme. Part of this programme is the survey of the consumption of radiopharmaceuticals from hospitals and their discharge to the environment. The basic data are delivered by the hospitals (yearly consumption of radiopharmaceuticals and the discharge of total activity in 131I–equivalents to the rivers). Several Swiss WWTPs and waste incineration plants, which are in the catchment area of hospitals, chemical radionuclide producing industries and watch industries are monitored continuously. Yearly, the BAG publishes the data [2].

#### **4.2. Sampling**

the waste water with activated sludge and oxygen, where most organic substances are degraded (7). The produced sewage sludge is isolated by sedimentation. At last, the waste water undergoes a secondary clarifying step (8). Over 90% of the organic carbon is degradable. Phosphates, which are the most important nutrient for algae, are eliminated by chemical precipitation. Nitrogen is not eliminated (e.g., by a nitrification/denitrification process). The so treated waste water is then released to the Rhine River below the city of Basel, near the border to Germany and France (B). The isolated sewage sludge is centrifuged (c, d). This thickened sludge is then burnt in fluidized

A total of 270,000 inhabitants of Basel City and surrounding villages (several villages of France and Germany included) release their waste waters to the waste net of the city, which has a length of about 360 km. It ends at the WWTP in the north of the city. The WWTP treats 82,000 m<sup>3</sup>

water originates from households (170 L of water are used per person per day). Special waste waters are discharged by the hospitals and industries. Waste waters from chemical industries in Basel are treated in a separate, independent WWTP, especially built for the treatment of chemical waste waters. For more details about the WWTP, visit the website of *ProRheno* [8].

The waste incineration plant *KVA Basel* has a capacity of 230,000 tonnes/year for burning wastes from households and permitted wastes from industries (that means 103 tonnes a day) [9]. Only 29% of the wastes are from the city of Basel. About 54% of the wastes are delivered from the state of Basel-Campaign and other Swiss states. The German Landkreis Lörrach delivers another 17%. The wastes originate from about 700,000 persons. They are burnt in two oven lines, which produce 537 GWh/year of heating energy (the value for energy consumption is 76%). The fire gases are cleaned in several steps: dust is eliminated by electrofilters. Nitrogen oxides are neutralised with ammonia. To destroy toxic dioxins and furans, special catalysts are used. The pre-cleaned air then undergoes a wet scrubbing with water. This waste water is treated on site with the incinerator's own treatment plant. The chemical quality of the cleaned water (about

/d) satisfies the quality criteria for treated waste water and can therefore be discharged directly to the Rhine River. The ashes are cooled down with water and stored in bunkers. About 43,800 tonnes of ashes are disposed of at a nearby landfill site. For more information, see [10].

Since 1956, environmental radioactivity has been continuously monitored in Switzerland. The motivation for the programme was the occurrence of the global fallout from bomb tests. Since 1986, the Federal Office of Public Health (BAG) is authorized to survey the ionising radiation and radioactivity in the environment. It has to organise a yearly monitoring programme. Part of this programme is the survey of the consumption of radiopharmaceuticals from hospitals and their discharge to the environment. The basic data are delivered by the hospitals (yearly

**3.2. The solid waste treatment at Basel: The municipal waste incineration plant of** 

waste water a year, respectively. About 40% of the waste

bed furnaces (9). The ashes are disposed at a nearby landfill site (**Figure 2**).

of waste water a day; 30 million m<sup>3</sup>

**Basel**

82 Sewage

190 m<sup>3</sup>

**4. Materials and methods**

**4.1. Swiss monitoring programme**

#### *4.2.1. Water samples*

For balancing radionuclides in waste water, a permanent sampling is necessary. This is only possible by using automatic water samplers. At the WWTP *ProRheno*, several samplers continuously collect water samples at several locations. Most important is the sampling of the untreated, raw waste water, before it enters the WWTP, and the treated waste water, before it is discharged to the Rhine River. The sampling rate of the samplers is fixed by the continuously recorded water flow rate. At higher rates, more water is sampled. Other samplers are necessary to control and optimise the waste water treatment processes inside the WWTP. At the waste incineration of Basel *KVA Basel*, the treated waste water from wet scrubbing of the flue gases is sampled permanently over 24 hours a day. This sampling is not operated by the water flow rate. The monitoring programmes of WWTP *ProRheno* and the waste incineration plant *KVA Basel* are based on water samples, which are representative for the whole time period (24 hours or a week). The water samples are delivered once a week to the State Laboratory of Basel City. The cleaned waste water from WWTP *ProRheno* consists of a 1 L sample, which was sampled over a whole week. The cleaned waste water contains a small amount of insoluble material (20–40 mg/L). The water samples from *KVA Basel* are daily samples, which are mixed in the laboratory to get a week sample. These samples are free from insoluble materials. The water samples are filled into 1 L Marinelli beakers for gamma ray spectrometry.

#### *4.2.2. Solid samples*

For the balancing experiments at WWTP *ProRheno*, sewage sludge and ash samples have to be analysed. These samples are filled into cylindrical beakers of 500 mL volume or, where possible, into 1 L Marinelli beakers. Sewer samples (sewer sludge or sewer slime) are collected in the waste net of the city of Basel. The sewer is filled into petri dishes (6.5 cm Ø). Considering the short half-lives of the radionuclides of interest (e.g., 99mTc), the gamma ray counting has to be started immediately after having received the samples. All solid samples were counted without drying to take into account the short half-life of some radionuclides and the volatility of certain radionuclides (e.g., 131I). Afterwards, all solid samples were dried at 110°C. All activities were calculated back to a dry-weight basis.

In 1980–2012, suspended matter of the Rhine River was collected in 50 L barrels in three months periods upstream of the city of Basel. The suspended matter was then co-precipitated with potassium zinc hexacyanoferrate-(II), clarified using Carrez solutions, dried and analysed with gamma ray spectrometry. After 2002, the suspended matter from Rhine River was sampled once a month at the *International Monitoring Station (Rüs) at Weil am Rhein*, Germany, near Basel. To filter off the suspended matter from the water, a centrifuge was continuously loaded with Rhine water. This water was a mixture of the Rhine water over the whole profile of the river. Depending on the water flow, the sampling time took one to several days. The suspended matter was freeze-dried in the laboratory of the Office for Environmental Protection and Energy Basel City. The dried material was ground and filled into petri dishes (6.5 cm Ø and 4 cm height, volume: 77 mL) for gamma ray counting [11]. The counting time for suspended matter was 2–3 days.

1998, higher activities for 131I near the limit value were noted. The activity limit of 5 Bq/L was not crossed, but the discharge activity of 12 GBq exceeded by far the limit of 50 kBq for 131I. In that year, four violations were noted. Three of the four violations were due to discharges of waste water from the University Hospital. The reasons for the violations were diverse: overfilling of waste water storage tanks, emptying of a wrong tank and technical problems with tank filling indication devices at the University Hospital. The State Laboratory Basel City started disciplinary proceedings against the responsible personnel [14]. The fourth violation was caused by the waste incineration plant of *KVA Basel*. At that time, the WWT at *KVA Basel* was stopped for revision works and the uncleaned waste water of the wet scrubbing was redirected for treatment to the WWTP *ProRheno*. This fourth violation demonstrated that radioac-

Since 1999, no more violations of the limit values (e.g., 5 Bq/L for 131I, see **Table 2**) have been noted. In 2005, first activities of 111In were detected in the treated waste water of the city. In 2003, the University Hospital of Basel started applications of 177Lu, which were growing over the years. This can clearly be seen in **Figure 3**. Besides 177Lu, 131I and 111In, other radionuclides are detected sporadically, such as 188Re, <sup>67</sup>Ga, 153Sm and 99mTc (**Table 3**). Radionuclides with very short half-lives, such as 99mTc or 18F, normally are not detected in

At the hospitals, only a part of the applied radioactivity is released to the waste net. A non negligible amount of radioactive wastes is released at homes. Here, all treated patients remain emission sources for the following weeks. In Section 5.3, we present measurements in the waste net that clearly show this fact. Most of the patients treated at the local hospitals live in

Originally, the monitoring programme of cleaned waste water from wet scrubbing of flue

tions of the limits occurred, but no polluter could be identified. In 2001, the monitoring was extended for the survey of radiopharmaceuticals. To date, 131I is the only radionuclide that caused several violations of the limit values. In April 2008, a violation of both limits for 131I was noted. The activity of the effluent was 30 Bq/L and the discharge was calculated to be 15 MBq/month; both values were clearly over the limit [16]. In May 2014, a further violation of 131I was noted. The mean activity then was 24 Bq/L (limit value: 5 Bq/L) and the discharge was 6.4 MBq per month (limit: 50 kBq/month) [17]. In both cases, no specific polluter could be found. We suppose that the 131I–containing wastes were delivered by the local hospitals. Other radiopharmaceuticals were only detected sporadically (**Figure 4**, **Table 4**). Without specific indications, it is almost impossible to find a polluter. *KVA Basel* has to deal with over 500 waste deliveries per day. In 2018, according to the revised Radioprotection Ordinance, waste incineration plants are obliged to install a gammadetecting portal where all wastes are monitored for gamma rays when delivered at the plant. Overall, the detected activities in the effluent of the waste incineration plant *KVA* 

H (tritium). From time to time, viola-

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 85

/day of waste

the vicinity of Basel. Their wastes are also treated at *ProRheno* and at *KVA Basel*.

*Basel* were of minor concern due to the low discharge volume of about 500 m<sup>3</sup>

**5.2. Waste water monitoring at the incineration plant** *KVA Basel*

gases was focused on the survey of the beta-nuclide <sup>3</sup>

tive contaminated wastes are also disposed of at *KVA Basel*.

the waste water [15].

water to Rhine River.

#### **4.3. Gamma ray spectrometry**

The water samples are filled without filtration into 1 L Marinelli beakers and counted for 24 hours with high resolution gamma ray spectrometers (Ge detectors). Different Ge detectors from Ortec and Canberra are used at the State Laboratory of Basel City (25–50% relative efficiencies, all detectors are of coaxial type). For recording and analysis of the pulse high spectra, Maestro Dspec jr. from Ortec combined with Interwinner-software from ITEC is used. Regularly, all detectors are recalibrated with calibration sources from Czech Metrology Institute at Prague (mixtures of 241Am and 152Eu). All spectra are background subtracted. For water samples, no density correction is necessary because of the same density of the calibration sources (*d* = 1.0). Solid samples are corrected according to their density and composition. No summation corrections are done. Experimental details are described in [12]. For the identification and quantification of the most important radionuclides, the following emission lines (with emission probability in %) are used: 131I: 284.3 keV (6.2), 364.5 keV (81.6) and 637.0 keV (7.1), 177Lu: 112.95 keV (6.4) and 208.4 keV (11.0), 177mLu: 208.4 keV (62.2), 228.4 keV (37.8) and 378.5 keV (28.3), 111In: 171.3 keV (90.2) and 245.4 keV (94.0), 186Re: 63.0 keV (1.9) and 137.2 keV (9.4), 99mTc: 140.5 keV (89.0), 153Sm: 69.7 keV (5.3) and 103.2 keV (28.3), 67Ga: 93.3 keV (39.0), 184.6 keV (21.3), 300.2 keV (16.8) and 393.5 keV (4.6), 110mAg: 657.8 keV (94.4), 763.9 keV (22.5), 884.7 keV (72.2) and 937.5 keV (34.3) and <sup>223</sup>Ra: 81.1 keV (14.9), 83.8 keV (24.5) and 94.9 keV (8.5).

#### **4.4. Beta ray spectrometry**

Radionuclides, such as 90Y, are pure beta-emitters. Therefore, pre-treatment is necessary before a sample can be analysed with beta-spectrometry. Hospitals usually convert these activities into 131I–equivalent values. For a specific analysis of 90Y, samples of 50–100 mL are prepared as follows. First, the 90Y is co-precipitated with oxalic acid in the presence of a non-active Y-carrier (Y<sup>3</sup> Cl). The precipitates are isolated and ashed at 850°C. They are then dissolved in HCl and precipitated again at a pH of 5. 40K and most of the alkaline earth metals are isolated in this step. The 90Y is then precipitated in a strong alkaline medium as Y<sup>2</sup> Ox<sup>3</sup> . The decay of 90Y in these pure beta-sources is measured in 10 consecutive runs of 400 minutes each by means of a gas proportional counter (LB 4000 from Canberra). Beta-background and relative efficiencies of the beta-detectors (30–40%) have to be considered. The beta-efficiencies of the detectors are regularly tested using own 90Sr/90Y oxalate sources [13].

#### **5. Results**

#### **5.1. The waste water monitoring at WWTP** *ProRheno*

In 1997, a monitoring programme for cleaned waste water was started in Basel. This treated waste water is analysed on a weekly basis for <sup>3</sup> H and gamma-active radiopharmaceuticals. In 1998, higher activities for 131I near the limit value were noted. The activity limit of 5 Bq/L was not crossed, but the discharge activity of 12 GBq exceeded by far the limit of 50 kBq for 131I. In that year, four violations were noted. Three of the four violations were due to discharges of waste water from the University Hospital. The reasons for the violations were diverse: overfilling of waste water storage tanks, emptying of a wrong tank and technical problems with tank filling indication devices at the University Hospital. The State Laboratory Basel City started disciplinary proceedings against the responsible personnel [14]. The fourth violation was caused by the waste incineration plant of *KVA Basel*. At that time, the WWT at *KVA Basel* was stopped for revision works and the uncleaned waste water of the wet scrubbing was redirected for treatment to the WWTP *ProRheno*. This fourth violation demonstrated that radioactive contaminated wastes are also disposed of at *KVA Basel*.

Since 1999, no more violations of the limit values (e.g., 5 Bq/L for 131I, see **Table 2**) have been noted. In 2005, first activities of 111In were detected in the treated waste water of the city. In 2003, the University Hospital of Basel started applications of 177Lu, which were growing over the years. This can clearly be seen in **Figure 3**. Besides 177Lu, 131I and 111In, other radionuclides are detected sporadically, such as 188Re, <sup>67</sup>Ga, 153Sm and 99mTc (**Table 3**). Radionuclides with very short half-lives, such as 99mTc or 18F, normally are not detected in the waste water [15].

At the hospitals, only a part of the applied radioactivity is released to the waste net. A non negligible amount of radioactive wastes is released at homes. Here, all treated patients remain emission sources for the following weeks. In Section 5.3, we present measurements in the waste net that clearly show this fact. Most of the patients treated at the local hospitals live in the vicinity of Basel. Their wastes are also treated at *ProRheno* and at *KVA Basel*.

#### **5.2. Waste water monitoring at the incineration plant** *KVA Basel*

The suspended matter was freeze-dried in the laboratory of the Office for Environmental Protection and Energy Basel City. The dried material was ground and filled into petri dishes (6.5 cm Ø and 4 cm height, volume: 77 mL) for gamma ray counting [11]. The counting time

The water samples are filled without filtration into 1 L Marinelli beakers and counted for 24 hours with high resolution gamma ray spectrometers (Ge detectors). Different Ge detectors from Ortec and Canberra are used at the State Laboratory of Basel City (25–50% relative efficiencies, all detectors are of coaxial type). For recording and analysis of the pulse high spectra, Maestro Dspec jr. from Ortec combined with Interwinner-software from ITEC is used. Regularly, all detectors are recalibrated with calibration sources from Czech Metrology Institute at Prague (mixtures of 241Am and 152Eu). All spectra are background subtracted. For water samples, no density correction is necessary because of the same density of the calibration sources (*d* = 1.0). Solid samples are corrected according to their density and composition. No summation corrections are done. Experimental details are described in [12]. For the identification and quantification of the most important radionuclides, the following emission lines (with emission probability in %) are used: 131I: 284.3 keV (6.2), 364.5 keV (81.6) and 637.0 keV (7.1), 177Lu: 112.95 keV (6.4) and 208.4 keV (11.0), 177mLu: 208.4 keV (62.2), 228.4 keV (37.8) and 378.5 keV (28.3), 111In: 171.3 keV (90.2) and 245.4 keV (94.0), 186Re: 63.0 keV (1.9) and 137.2 keV (9.4), 99mTc: 140.5 keV (89.0), 153Sm: 69.7 keV (5.3) and 103.2 keV (28.3), 67Ga: 93.3 keV (39.0), 184.6 keV (21.3), 300.2 keV (16.8) and 393.5 keV (4.6), 110mAg: 657.8 keV (94.4), 763.9 keV (22.5), 884.7 keV (72.2) and 937.5 keV (34.3) and <sup>223</sup>Ra: 81.1 keV (14.9), 83.8 keV (24.5) and 94.9 keV (8.5).

Radionuclides, such as 90Y, are pure beta-emitters. Therefore, pre-treatment is necessary before a sample can be analysed with beta-spectrometry. Hospitals usually convert these activities into 131I–equivalent values. For a specific analysis of 90Y, samples of 50–100 mL are prepared as follows. First, the 90Y is co-precipitated with oxalic acid in the presence of a non-active

HCl and precipitated again at a pH of 5. 40K and most of the alkaline earth metals are isolated

in these pure beta-sources is measured in 10 consecutive runs of 400 minutes each by means of a gas proportional counter (LB 4000 from Canberra). Beta-background and relative efficiencies of the beta-detectors (30–40%) have to be considered. The beta-efficiencies of the detectors

In 1997, a monitoring programme for cleaned waste water was started in Basel. This treated

in this step. The 90Y is then precipitated in a strong alkaline medium as Y<sup>2</sup>

are regularly tested using own 90Sr/90Y oxalate sources [13].

**5.1. The waste water monitoring at WWTP** *ProRheno*

waste water is analysed on a weekly basis for <sup>3</sup>

Cl). The precipitates are isolated and ashed at 850°C. They are then dissolved in

Ox<sup>3</sup>

H and gamma-active radiopharmaceuticals. In

. The decay of 90Y

for suspended matter was 2–3 days.

**4.3. Gamma ray spectrometry**

84 Sewage

**4.4. Beta ray spectrometry**

Y-carrier (Y<sup>3</sup>

**5. Results**

Originally, the monitoring programme of cleaned waste water from wet scrubbing of flue gases was focused on the survey of the beta-nuclide <sup>3</sup> H (tritium). From time to time, violations of the limits occurred, but no polluter could be identified. In 2001, the monitoring was extended for the survey of radiopharmaceuticals. To date, 131I is the only radionuclide that caused several violations of the limit values. In April 2008, a violation of both limits for 131I was noted. The activity of the effluent was 30 Bq/L and the discharge was calculated to be 15 MBq/month; both values were clearly over the limit [16]. In May 2014, a further violation of 131I was noted. The mean activity then was 24 Bq/L (limit value: 5 Bq/L) and the discharge was 6.4 MBq per month (limit: 50 kBq/month) [17]. In both cases, no specific polluter could be found. We suppose that the 131I–containing wastes were delivered by the local hospitals. Other radiopharmaceuticals were only detected sporadically (**Figure 4**, **Table 4**). Without specific indications, it is almost impossible to find a polluter. *KVA Basel* has to deal with over 500 waste deliveries per day. In 2018, according to the revised Radioprotection Ordinance, waste incineration plants are obliged to install a gammadetecting portal where all wastes are monitored for gamma rays when delivered at the plant. Overall, the detected activities in the effluent of the waste incineration plant *KVA Basel* were of minor concern due to the low discharge volume of about 500 m<sup>3</sup> /day of waste water to Rhine River.

realised for the monitoring of specific emissions sources, which are under suspicion to violate the law. Another approach is the monitoring of sewer sludge or sewer slime. Sewer sludge is called a biofilm that grows on the interface of the waste water and the concrete of the waste net. Algae, bacteria and fungi build this biofilm, which acts as an excellent sorbent surface for many contaminants, such as heavy metals, polycyclic aromatic hydrocarbons, organochlorine compounds etc. [18, 19]. Radionuclides too, are adsorbed on this biofilms. The substances stay adsorbed until they are washed away from the concrete walls together with the sewer sludge or, in the case of the radionuclides, they have disintegrated. Therefore, sewer sludge can serve

**Radionuclide Activity range Number of positive samples Mean ± s.d.** <sup>131</sup>I <0.1–4.8 1015 0.3 ± 0.3 177Lu <0.5–5.2 605 0.6 ± 0.9 111In <0.1–0.6 97 0.2 ± 0.1 <sup>67</sup>Ga <0.3–8.4 48 0.5 ± 1.5 <sup>186</sup>Re <0.5–23 7 4.4 ± 7.8 153Sm <0.3–0.72 3 0.5 ± 0.2

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**Table 5** shows impressively the discrepancy between random sampling of waste water and the sampling of sewer sludge, which memorizes contamination of the waste system for a certain time. Only at two positions, site B and E, were traces of 131I and 177Lu detectable in the waste water on the sampling day, whereas 131I and 177Lu were detectable in the sewer sludge of several sites above and below the emission source. These activities are the result from past discharges of radioactive waste water. The fact that even above the emission source, radionuclides were detected shows that patients at home are also emission sources for a certain time [21]. The sampling of sewer sludge illustrates the contamination of the waste net over a certain time period (some days, depending on the half-life of the analysed radionuclide); but it is not representative enough for the calculation of loads or the release of radionuclides in the waste net. Sewer slime analyses can be very useful to look for specific emission sources in

In 2014, Rumpel analysed influents and effluents of the WWTP *ProRheno* for two time periods of a month [20]. During this time, 24 hour samples from the untreated waste water and the cleaned waste water were collected and analysed with gamma ray spectrometry. Samples were collected with automatic samplers at the entrance of the WWTP (untreated waste water) and before the cleaned waste water was discharged to the Rhine River (cleaned waste water). The accumulated sewage sludge was collected and analysed daily before it was burnt. The ashes were collected in containers for transportation to the landfill site. Samples were taken from each container (four samples a month). The activities of the discharges were calculated

as a memory of the load of the run through waste water (**Figure 5**) [20].

**Table 3.** Overview of the waste water monitoring at WWTP *ProRheno* from 1999 to 2016.

a waste net [20].

**5.4. Balance of radiopharmaceuticals at WWTPs**

All values in Bq/kg. s.d.: standard deviation.

**Figure 3.** Monitoring of the treated waste water of the WWTP *ProRheno* since 1997.

#### **5.3. Detection of radioactive contamination in the waste net**

The investigation of waste water by taking random samples in a waste net does not lead to representative results. This can only be achieved by using automatic water samplers. The installation and use of such samplers in the waste net is a difficult task. Therefore, it is only


**Table 3.** Overview of the waste water monitoring at WWTP *ProRheno* from 1999 to 2016.

realised for the monitoring of specific emissions sources, which are under suspicion to violate the law. Another approach is the monitoring of sewer sludge or sewer slime. Sewer sludge is called a biofilm that grows on the interface of the waste water and the concrete of the waste net. Algae, bacteria and fungi build this biofilm, which acts as an excellent sorbent surface for many contaminants, such as heavy metals, polycyclic aromatic hydrocarbons, organochlorine compounds etc. [18, 19]. Radionuclides too, are adsorbed on this biofilms. The substances stay adsorbed until they are washed away from the concrete walls together with the sewer sludge or, in the case of the radionuclides, they have disintegrated. Therefore, sewer sludge can serve as a memory of the load of the run through waste water (**Figure 5**) [20].

**Table 5** shows impressively the discrepancy between random sampling of waste water and the sampling of sewer sludge, which memorizes contamination of the waste system for a certain time. Only at two positions, site B and E, were traces of 131I and 177Lu detectable in the waste water on the sampling day, whereas 131I and 177Lu were detectable in the sewer sludge of several sites above and below the emission source. These activities are the result from past discharges of radioactive waste water. The fact that even above the emission source, radionuclides were detected shows that patients at home are also emission sources for a certain time [21]. The sampling of sewer sludge illustrates the contamination of the waste net over a certain time period (some days, depending on the half-life of the analysed radionuclide); but it is not representative enough for the calculation of loads or the release of radionuclides in the waste net. Sewer slime analyses can be very useful to look for specific emission sources in a waste net [20].

#### **5.4. Balance of radiopharmaceuticals at WWTPs**

**5.3. Detection of radioactive contamination in the waste net**

86 Sewage

**Figure 3.** Monitoring of the treated waste water of the WWTP *ProRheno* since 1997.

The investigation of waste water by taking random samples in a waste net does not lead to representative results. This can only be achieved by using automatic water samplers. The installation and use of such samplers in the waste net is a difficult task. Therefore, it is only In 2014, Rumpel analysed influents and effluents of the WWTP *ProRheno* for two time periods of a month [20]. During this time, 24 hour samples from the untreated waste water and the cleaned waste water were collected and analysed with gamma ray spectrometry. Samples were collected with automatic samplers at the entrance of the WWTP (untreated waste water) and before the cleaned waste water was discharged to the Rhine River (cleaned waste water). The accumulated sewage sludge was collected and analysed daily before it was burnt. The ashes were collected in containers for transportation to the landfill site. Samples were taken from each container (four samples a month). The activities of the discharges were calculated

**Radionuclide Activity range Number of positive samples Mean ± s.d.** <sup>131</sup>I <0.1–36 708 1.0 ± 2.8 111In <0.1–1.6 7 0.7 ± 0.6 177Lu <0.5–2.7 6 1.0 ± 0.8 153Sm <0.3–34 4 11 ± 13 110mAg <0.1–0.14 3 0.1 ± 0.03 <sup>186</sup>Re <0.5–9.6 2 5.4 ± 4.2

**Table 4.** Overview of the waste water monitoring at the waste incineration *KVA Basel* from 2001 to 2016.

**Figure 5.** Sewer sludge (left) and the sampling of it in the waste net (right).

Above University Hospital

Below University Hospital

source (university hospital Basel).

Site A Site B

Site C Site D Site E

**Sample date: 21.10.2014 Waste water (Bq/L) Sewer sludge (Bq/kg d.w.)** Radionuclide analysed <sup>131</sup>I 177Lu <sup>131</sup>I 177Lu

> <0.3 <0.3

> <0.4 <0.4 4

**Table 5.** Comparison of waste water and sewer sludge at the same places in the waste net above and below the emission

<1 564

<1 <1 115 32 <20

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 89

282 <4 9.570

<0.1 1.2

<0.1 <0.1 <0.1

All values in Bq/kg. s.d.: standard deviation.

**Figure 4.** Monitoring of the cleaned effluent from wet scrubbing at the waste incineration plant *KVA Basel* since 2001.

by multiplying the activities with the daily waste water and sewage sludge discharges. **Table 6** shows clearly the bad elimination of 131I. Only 14% are eliminated by the WWT process. Almost 90% of the 131I is dissolved in the water, passes the WWT and is discharged to Rhine River. The 14%, which are taken out of the waste water are lost by the burning of the sewage sludge (the ashes are free of 131I). On the other hand, 42% of 177Lu was eliminated in the WWT. This is not surprising. It corresponds to the elimination rate of heavy metals. The eliminated part

#### Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 89


**Table 4.** Overview of the waste water monitoring at the waste incineration *KVA Basel* from 2001 to 2016.

**Figure 5.** Sewer sludge (left) and the sampling of it in the waste net (right).

by multiplying the activities with the daily waste water and sewage sludge discharges. **Table 6** shows clearly the bad elimination of 131I. Only 14% are eliminated by the WWT process. Almost 90% of the 131I is dissolved in the water, passes the WWT and is discharged to Rhine River. The 14%, which are taken out of the waste water are lost by the burning of the sewage sludge (the ashes are free of 131I). On the other hand, 42% of 177Lu was eliminated in the WWT. This is not surprising. It corresponds to the elimination rate of heavy metals. The eliminated part

**Figure 4.** Monitoring of the cleaned effluent from wet scrubbing at the waste incineration plant *KVA Basel* since 2001.

88 Sewage


**Table 5.** Comparison of waste water and sewer sludge at the same places in the waste net above and below the emission source (university hospital Basel).


to Rhine River [32]. As a consequence, in 1982, the suspended matter contained 14.8 Bq/kg of 131I and 88 Bq/kg of 137Cs. Additionally, some activation products typically found in emissions

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 91

In 1986, 2,580 ± 1,680 Bq/kg of 131I were found in the suspended matter of Rhine River, together with 1,720 ± 930 Bq/kg of 134Cs and 3,500 ± 1,740 Bq/kg of 137Cs. These high contaminations originated from the fallout of the reactor fire at Chernobyl in that year [34]. Only after 2006, a regular monitoring for short-lived radionuclides from pharmaceutical use was realised. When short-lived radionuclides have to be monitored, it is important to analyse the collected suspended matter as soon as possible. Before 2006, samples were collected over a year and analysed at the end of the year. Therefore, the short-lived radionuclides were already disintegrated. In suspended matter, the radionuclides 131I and 177Lu are prominent. Since 2009, they are detectable in almost every sample and reflect mainly the local emissions from the WWTP *ProRheno* (**Figure 6, Table 7**). In 2015 and 2016, the radionuclide 177mLu was found. We suppose

**Figure 6.** Results from monitoring of suspended matter of Rhine River. All annual average values in Bq/kg dry weight.

**Radionuclide Activity range Number of positive samples Mean ± s.d.** <sup>67</sup>Ga 0–59 7 30 ± 21 85Sr 0–83 21 25 ± 22 <sup>131</sup>I 0–258 94 5.8 ± 5.6 153Sm 0–183 6 105 ± 65 169Er 0–1,550 1 1,550 177Lu 0–390 92 82 ± 117 177mLu 0–3 4 3.0 ± 0.1 <sup>186</sup>Re 0–1,034 1 1,934 223Ra 0–33 8 16 ± 8.2

**Table 7.** Development of yearly mean activities in suspended matter from 1982 to 2016.

All values in Bq/kg dry weight.

from NPPs, such as 60Co (85 Bq/kg) and 54Mn (14.8 Bq/kg), could be detected [33].

**Table 6.** Balance of radionuclides in the WWTP *ProRheno*.

remains in the ashes from the burning of the sewage sludge, where it disintegrates according to its half-life of 6.7 days [14].

For 131I, similar observations were reported by Rose. The investigations of six WWTP's in USA showed that most of the 131I passed the WWTP's with the treated waste water [22]. In Finland, most of the 131I (up to 94 Bq/L) was found in the water phase, whereas, in the sewage sludge, <sup>51</sup>Cr, 111In, 201/202Tl and other radionuclides were found. Also, sporadically other radionuclides from nuclear power stations were detectable, such as 58Co, <sup>60</sup>Co, 110mAg, or 124Sb [23]. In Kurume City, Japan, four hospitals discharge their waste waters to the local WWTP. The main activities of radiopharmaceuticals were found in the waste water. About 1–4% of the applied activities of 99mTc, 123I, 67Ga and 201Tl were detected in the WWTP. 131I was only found in the sewage sludge [24]. This is confirmed by others. Investigations in Canada, Italy, France and Sweden showed that the main activities were in the sewage sludge [25–28]. About 1–250 Bq/kg of 201Tl, 99mTc, 131I were measured in the sewage sludge of French WWTPs [29]. In the WWTP of Valladolid, Spain, 75–1238 Bq/kg d.w. of 131I was found in sewage sludge [30]. Hormann and Fischer investigated the WWTP of Bremen-Seehausen in Germany. They found an overall elimination rate of 50–75% for 131I. Most of the 131I was bound to the sewage sludge. They concluded that 131I was bound to the return sludge and therefore a longer residence time of the waste water resulted. About 30% of the input was organically bound. After the cleaning processes, over 90% was organically bound and therefore could be eliminated from the waste water cycle [31].

Such discrepancies of the fate of radiopharmaceuticals in WWTPs can be explained as follows. The waste water treatment processes, which can vary from WWTP to WWTP, also have influence on the behaviour of the radiopharmaceuticals during the waste water cleaning process. How radiopharmaceuticals are administered (inorganic unbound, or organically bound) is crucial for the elimination behaviour of radiopharmaceuticals in a WWTP.

#### **5.5. Monitoring of suspended matter of Rhine River at Basel**

Since 1982, the suspended matter of Rhine River is collected periodically and analysed for radio contamination. This is part of the monitoring programmes of the BAG for the survey of Swiss Nuclear Power Plants (NPP) and WWTPs. From 1982 to 2002, suspended matter was collected in three month periods upstream of the city of Basel. Since 2002, suspended matter was collected monthly by means of a centrifuge at the river monitoring station Weil am Rhein downstream of the city.

In 1982 and 1986, high activities of 131I were found in suspended matter of Rhine River. In 1982, the NPP of Mühleberg discharged radioactive water to Aar River, which is connected to Rhine River [32]. As a consequence, in 1982, the suspended matter contained 14.8 Bq/kg of 131I and 88 Bq/kg of 137Cs. Additionally, some activation products typically found in emissions from NPPs, such as 60Co (85 Bq/kg) and 54Mn (14.8 Bq/kg), could be detected [33].

In 1986, 2,580 ± 1,680 Bq/kg of 131I were found in the suspended matter of Rhine River, together with 1,720 ± 930 Bq/kg of 134Cs and 3,500 ± 1,740 Bq/kg of 137Cs. These high contaminations originated from the fallout of the reactor fire at Chernobyl in that year [34]. Only after 2006, a regular monitoring for short-lived radionuclides from pharmaceutical use was realised. When short-lived radionuclides have to be monitored, it is important to analyse the collected suspended matter as soon as possible. Before 2006, samples were collected over a year and analysed at the end of the year. Therefore, the short-lived radionuclides were already disintegrated. In suspended matter, the radionuclides 131I and 177Lu are prominent. Since 2009, they are detectable in almost every sample and reflect mainly the local emissions from the WWTP *ProRheno* (**Figure 6, Table 7**). In 2015 and 2016, the radionuclide 177mLu was found. We suppose

remains in the ashes from the burning of the sewage sludge, where it disintegrates according

**Sewage sludge**

**Ash from sewage** 

**Elimination rate %**

**sludge**

**Treated waste water**

<sup>131</sup>I 812 701 52 0.2 ~14 177Lu 5.500 3.207 1.628 856 ~42

For 131I, similar observations were reported by Rose. The investigations of six WWTP's in USA showed that most of the 131I passed the WWTP's with the treated waste water [22]. In Finland, most of the 131I (up to 94 Bq/L) was found in the water phase, whereas, in the sewage sludge, <sup>51</sup>Cr, 111In, 201/202Tl and other radionuclides were found. Also, sporadically other radionuclides from nuclear power stations were detectable, such as 58Co, <sup>60</sup>Co, 110mAg, or 124Sb [23]. In Kurume City, Japan, four hospitals discharge their waste waters to the local WWTP. The main activities of radiopharmaceuticals were found in the waste water. About 1–4% of the applied activities of 99mTc, 123I, 67Ga and 201Tl were detected in the WWTP. 131I was only found in the sewage sludge [24]. This is confirmed by others. Investigations in Canada, Italy, France and Sweden showed that the main activities were in the sewage sludge [25–28]. About 1–250 Bq/kg of 201Tl, 99mTc, 131I were measured in the sewage sludge of French WWTPs [29]. In the WWTP of Valladolid, Spain, 75–1238 Bq/kg d.w. of 131I was found in sewage sludge [30]. Hormann and Fischer investigated the WWTP of Bremen-Seehausen in Germany. They found an overall elimination rate of 50–75% for 131I. Most of the 131I was bound to the sewage sludge. They concluded that 131I was bound to the return sludge and therefore a longer residence time of the waste water resulted. About 30% of the input was organically bound. After the cleaning processes, over 90% was

organically bound and therefore could be eliminated from the waste water cycle [31].

is crucial for the elimination behaviour of radiopharmaceuticals in a WWTP.

**5.5. Monitoring of suspended matter of Rhine River at Basel**

Such discrepancies of the fate of radiopharmaceuticals in WWTPs can be explained as follows. The waste water treatment processes, which can vary from WWTP to WWTP, also have influence on the behaviour of the radiopharmaceuticals during the waste water cleaning process. How radiopharmaceuticals are administered (inorganic unbound, or organically bound)

Since 1982, the suspended matter of Rhine River is collected periodically and analysed for radio contamination. This is part of the monitoring programmes of the BAG for the survey of Swiss Nuclear Power Plants (NPP) and WWTPs. From 1982 to 2002, suspended matter was collected in three month periods upstream of the city of Basel. Since 2002, suspended matter was collected monthly by means of a centrifuge at the river monitoring station Weil am Rhein

In 1982 and 1986, high activities of 131I were found in suspended matter of Rhine River. In 1982, the NPP of Mühleberg discharged radioactive water to Aar River, which is connected

to its half-life of 6.7 days [14].

**Untreated waste** 

**Table 6.** Balance of radionuclides in the WWTP *ProRheno*.

**water**

**Radionuclide MBq/m3**

90 Sewage

downstream of the city.


**Figure 6.** Results from monitoring of suspended matter of Rhine River. All annual average values in Bq/kg dry weight.

**Table 7.** Development of yearly mean activities in suspended matter from 1982 to 2016.

that this nuclide was applied instead of 177Lu, when there were supply difficulties for 177Lu. 177mLu has a long half-life of 161 days and should therefore not be regularly used for pharmaceutical applications. It remains much longer in the environment, where it can cause damage. Other radionuclides, such as 67Ga, 153Sm, or 85Sr, were found sporadically. Here, different sources (hospitals), connected to the Rhine River catchment, are possible. Since 2015, <sup>223</sup>Ra can regularly be found in the suspended matter. Overall, over these years, there were observed no violation of the immission limits for rivers according to the Radioprotection Ordinance. These limits are defined for activities of the river water. In suspended matter, these radionuclides are highly enriched by the collection process of the suspended matter. Supposing a total adsorption of the radionuclides to the suspended particles, the enrichment factor is 1000 and more. Nevertheless, there is only poor knowledge about the low dose effects of radiation on aquatic organisms.

**References**

2016. pp. 167-170

2017]

December 27, 2017]

2013;**67**:828

[1] Radvanyi P. Les Curies. Pionniers de l'atome. 2005. BELIN-pour la science, Paris, 102ff [2] Federal Office of Public Health. Environmental Radioactivity and Radiation Doses in Switzerland, yearly report. Bern: BAG. Available at:https://www.bag.admin.ch/bag/ de/home/service/publikationen/jahresberichte/jahresberichte-umweltradioaktivitaet

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 93

[3] Linder R, Stritt N, Flury T. Emissions from Hospitals. In: Federal Office of Public Health, editor. Environmental Radioactivity and Radiation Doses in Switzerland. Bern: BAG;

[4] Yearly report of the radiology and nuclear medicine of the University Hospital of Basel. Available at: https://www.unispital-Basel.ch/fileadmin/unispitalbaselch/ Bereiche/ Quer schnittsfunktionen/Medizinische\_Radiologie/Radiologie/Files\_zur\_KRN/Jahresbericht\_

[5] Federal Assembly of the Swiss Confederation. Radiological Protection Act; 1991. Status: 1 May 2017.Available at:https://www.admin.ch/opc/en/classified-compilation/19910045/

[6] Swiss Federal Council: Radiological Protection Ordinance; 1994. Status: 1 January 2014. Available at:https://www.admin.ch/opc/en/classified-compilation/19940157/

[7] Waste Water Treatment Plant *ProRheno AG*. Informations Available at: http://www.pro-

[8] WWTP *ProRheno AG*. Yearly report. 2016. Available at:http://www.prorheno.ch/media/ 75LH1RCY/170512\_ProRheno\_AG\_Jahresbericht\_2016.pdf [Accessed: December 27,

[9] Waste incineration *KVA Basel*. Available at: https://www.iwb.ch/Ueber-uns/Kehricht-

[10] Waste incineration *KVA Basel*. Yearly report. 2016. Available at: https://www.iwb.ch/ dam/jcr:b0e73138-9a71-4712-9e03-420ebb5786a8/KVA\_UB\_2016\_WEB.pdf [Accessed:

[11] Zehringer M, Mazacek J, Dolf R, Testa G, Jourdan J. Neutron activation analysis – Another approach to uranium and thorium analysis in environmental samples. Chimia.

[12] Zehringer *M.* Gamma Ray spectrometry and the investigation of environmental and food samples. In: Ahmed M. Maghraby, editor. New Insights on Gamma Rays. Croatia:

verwertung/Alles-ueber-die-KVA.html [Accessed: December 27, 2017]

html#par\_text [Accessed: December 27, 2017]

Radiologie\_2016.pdf [Accessed: December 27, 2017]

201705010000/814.50.pdf [Accessed: December 27, 2017]

201401010000/814.501.pdf. [Accessed: December 27, 2017]

rheno.ch/home [Accessed: December 27, 2017]

InTech Open; 2017. ISBN: 978-953-51-3762-5

#### **6. Conclusion**

Our monitoring programmes for radiopharmaceuticals show that radioactivity is permanently released to the environment despite rigorous treatment and cleaning of the radioactive wastes from hospitals. The limits for radionuclides in rivers and lakes are observed. Nevertheless, little is known about the low dose effects of radiation on aquatic organisms, which may occur well below these limits. Overall, the permanent monitoring of radionuclides in the environment of cities remains an important task.

#### **Acknowledgements**

I would like to thank the operators of the WWTP *ProRheno* and the Waste Incineration Plant *KVA Basel* for their permanent supply with water samples over the last 25 years. I also thank Reto Dolf from the Office for Environmental Protection and Energy Basel City for his constant scientific support and supply of water samples and suspended matter samples of the Rhine River. Finally, I want to thank my collaborators Franziska Kammerer, Matthias Stöckli and Michael Wagmann of the State Laboratory of Basel City for analysing the numerous environmental samples.

#### **Author details**

Markus R. Zehringer Address all correspondence to: markus.zehringer@bs.ch State Laboratory Basel-City, Kannenfeldstr, Switzerland

#### **References**

that this nuclide was applied instead of 177Lu, when there were supply difficulties for 177Lu. 177mLu has a long half-life of 161 days and should therefore not be regularly used for pharmaceutical applications. It remains much longer in the environment, where it can cause damage. Other radionuclides, such as 67Ga, 153Sm, or 85Sr, were found sporadically. Here, different sources (hospitals), connected to the Rhine River catchment, are possible. Since 2015, <sup>223</sup>Ra can regularly be found in the suspended matter. Overall, over these years, there were observed no violation of the immission limits for rivers according to the Radioprotection Ordinance. These limits are defined for activities of the river water. In suspended matter, these radionuclides are highly enriched by the collection process of the suspended matter. Supposing a total adsorption of the radionuclides to the suspended particles, the enrichment factor is 1000 and more. Nevertheless, there is only poor knowledge about the low dose effects of radiation on

Our monitoring programmes for radiopharmaceuticals show that radioactivity is permanently released to the environment despite rigorous treatment and cleaning of the radioactive wastes from hospitals. The limits for radionuclides in rivers and lakes are observed. Nevertheless, little is known about the low dose effects of radiation on aquatic organisms, which may occur well below these limits. Overall, the permanent monitoring of radionuclides

I would like to thank the operators of the WWTP *ProRheno* and the Waste Incineration Plant *KVA Basel* for their permanent supply with water samples over the last 25 years. I also thank Reto Dolf from the Office for Environmental Protection and Energy Basel City for his constant scientific support and supply of water samples and suspended matter samples of the Rhine River. Finally, I want to thank my collaborators Franziska Kammerer, Matthias Stöckli and Michael Wagmann of the State Laboratory of Basel City for analysing the numerous environ-

in the environment of cities remains an important task.

Address all correspondence to: markus.zehringer@bs.ch State Laboratory Basel-City, Kannenfeldstr, Switzerland

aquatic organisms.

92 Sewage

**6. Conclusion**

**Acknowledgements**

mental samples.

**Author details**

Markus R. Zehringer


[13] Zehringer M, Wagmann M, Kammerer F. Trace analysis of radiostrontium in food samples by means of beta-spectrometry at the sub-becquerel level. Swiss Food Science Meeting 2013

[28] Coangelo S, Cortellessa G, Terrani S. Radioactivity measurement in the sewage of some

Fate of Radiopharmaceuticals in the Environment http://dx.doi.org/10.5772/intechopen.74665 95

[29] Barci-Funel G, Dalmasso J, Magne J, Ardisson G. Simultaneous detection of short-lived thallium-201, metastable technetium-99 and iodine-131 isotopes in sewage sludge using low energy photon spectrometry. Science of the Total Environment. 1993;**130-131**:37-42

[30] Jimenez F, Deban L, Pardo R, Lopez R, Garcia-Talavera M. Levels of 131I and six natural radionuclides in sludge from the sewage treatment plant of Valladolid, Spain. Water,

[31] Hormann V, Fischer H. The physicochemical distribution of 131I in a municipal wastewater treatment plant. Journal of Environmental Radioactivity. 2017;**178-179**:55-62

[32] Jäggi M, et al. 137Cs, 241Am and 239,240Pu in einem Sediment des Klingnauer Stausees. In: Umweltradioaktivität und Strahlendosen in der Schweiz 2014. Federal Office of Public

[33] Herrmann A. Radioactivity. Investigations of water samples. In: Annual Report of the

[34] Herrmann A. Radioactivity. Investigations of Water Samples. In: Annual Report of the

Italian cities. RT/PROT-(73). 1973;**35**:9

Air, and Soil Pollution. 2011;**217**:515-521

State-Laboratory Basel-City. Basel. 1982. p. 35

State-Laboratory Basel-City. Basel. 1986. p. 48

Health, ed. pp. 74-77


[28] Coangelo S, Cortellessa G, Terrani S. Radioactivity measurement in the sewage of some Italian cities. RT/PROT-(73). 1973;**35**:9

[13] Zehringer M, Wagmann M, Kammerer F. Trace analysis of radiostrontium in food samples by means of beta-spectrometry at the sub-becquerel level. Swiss Food Science

[14] Figueiredo V. Radioactivity in the environment. In: Annual Report of the State-

[15] Kammerer F, Rumpel N, Wagmann M, Zehringer M. Monitoring of Radionuclides for Medical Use in Basel. Dresden: Proceedings of the GDCH-Wissenschaftsforum; 2015 [16] Zehringer M. Waste water monitoring of the incineration plant *KVA Basel*. In: Annual

[17] Zehringer M. Waste water monitoring of the incineration plant *KVA Basel*. In: Annual

[18] Gutekunst B. Sielhautuntersuchungen zur Einkreisung schwermetallhaltiger Einleitungen (Thesis). Schriftenreihe des Instituts für Siedlungswasserwirtschaft der Uni-

[19] Sauer J, Antusch E, Ripp C. Monitoring lipophiler organische Schadstoffe im Kanalnetz

[20] Rumpel N, Kammerer F, Wagmann M, Zehringer *M*. Gamma Ray spectrometry of sewer sludge – A useful tool for the identification of emission sources in a city. Chimia 2015;

[21] Rumpel N. Balance of Radiopharmaceuticals in the Vicinity of Basel [Scholarly Paper].

[22] Rose P. Occurrence and concentrations of medically-derived iodine-131 in municipal sewage and sewage sludge. Proceedings – Water Quality Technology Conference and

[23] Puhakainen M, Sukomela M. Detection of radionuclides originating from a nuclear power plant in sewage sludge. Sateilyturvakeskus, Rapportti STUK-A. 1999;**154**:1-27 [24] Nakamura A, Osaki S, Hayabuchi N. Behavior of the medical radionuclides in municipal

[25] Durham R, Joshi S. Radionuclide concentrations in two sewage treatment plants on western Lake Ontario, Canada. The Journal of Radioanalytical and Nuclear Chemistry.

[26] Dalmasso D, Barci-Funel G, Magne J, Barci V, Ardisson G. Study of the transfer of the medically used radionuclides in sewage systems. Radiochimica Acta. 1997;**78**:167-171

[27] Erlandsson B, Mattsson S. Medically used radionuclides in sewage sludge. Water, Air,

Report of the State-Laboratory Basel-City. Basel. 2008. pp. 152-154

Report of the State-Laboratory Basel-City. Basel. 2014. pp. 152-155

mittels Sielhautuntersuchungen. Vom Wasser. 1997;**88**:49-69

Muttenz: State Grammar School Muttenz; 2015

sewage treatment plants. Radioisotopes. 2001;**50**:343-352

Meeting 2013

94 Sewage

Laboratory Basel-City. Basel;1998. p.114

versität Karlsruhe. 1988:49

**69**: 301

Exposition 2013; **y**:1

1979;**54**:367-370

and Soil Pollution. 1978;**9**:199-206


**Chapter 6**

**Provisional chapter**

**Municipal Sewage Sludge Variability: Biodegradation**

**Municipal Sewage Sludge Variability: Biodegradation** 

Municipal sewage sludge is a waste with high organic load generated in large quantities that can be treated by biodegradation techniques such as composting to reduce its risk to the environment. This research studies the physicochemical variability of sewage sludge from treatment plants in the south of Galicia (Spain) and determines if it is possible to establish a protocol for the use of bulking agent depending on the composition of the sludge and the development of the composting process. Therefore, physicochemical analyses of 35 sewage sludge from different municipalities and 10 samples from the same treatment plant are discussed. Three different mixtures bulking agent:sewage sludge (3:1, 2:1, 1:1, v:v) were carried out in 30 L reactors in triplicate. Finally, proportion 2:1 was replicated six times in a 600 L reactor. High inter-sludge variability was observed specially in key parameters such as moisture and C/N ratio. Intra-variability was lower, and 2:1 proportion was the most suitable mixture since extending the thermophilic phase of the composting process at a greater degree. However, repeatability of the process at a higher scale showed different responses in the temperature evolution. Variability of sewage sludge makes difficult to establish treatment protocols although minimum requirements are necessary for proper composting. **Keywords:** stabilization, compost quality, bulking agent, organic matter, sanitation

As a result of the usual human activities, a large amount and volume of wastes from different sources that vary in composition and toxicity are generated. An important fraction of this waste is organic biodegradable material that has different characteristics that depend, fundamentally, on its origin: agricultural, forestry, agro-industrial, or urban. In general, the uncontrolled

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.75130

**through Composting with Bulking Agent**

**through Composting with Bulking Agent**

David Alves Comesaña, Iria Villar Comesaña and

David Alves Comesaña, Iria Villar Comesaña and

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Salustiano Mato de la Iglesia

Salustiano Mato de la Iglesia

**Abstract**

**1. Introduction**

http://dx.doi.org/10.5772/intechopen.75130

#### **Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent**

DOI: 10.5772/intechopen.75130

David Alves Comesaña, Iria Villar Comesaña and Salustiano Mato de la Iglesia David Alves Comesaña, Iria Villar Comesaña and Salustiano Mato de la Iglesia

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.75130

#### **Abstract**

Municipal sewage sludge is a waste with high organic load generated in large quantities that can be treated by biodegradation techniques such as composting to reduce its risk to the environment. This research studies the physicochemical variability of sewage sludge from treatment plants in the south of Galicia (Spain) and determines if it is possible to establish a protocol for the use of bulking agent depending on the composition of the sludge and the development of the composting process. Therefore, physicochemical analyses of 35 sewage sludge from different municipalities and 10 samples from the same treatment plant are discussed. Three different mixtures bulking agent:sewage sludge (3:1, 2:1, 1:1, v:v) were carried out in 30 L reactors in triplicate. Finally, proportion 2:1 was replicated six times in a 600 L reactor. High inter-sludge variability was observed specially in key parameters such as moisture and C/N ratio. Intra-variability was lower, and 2:1 proportion was the most suitable mixture since extending the thermophilic phase of the composting process at a greater degree. However, repeatability of the process at a higher scale showed different responses in the temperature evolution. Variability of sewage sludge makes difficult to establish treatment protocols although minimum requirements are necessary for proper composting.

**Keywords:** stabilization, compost quality, bulking agent, organic matter, sanitation

#### **1. Introduction**

As a result of the usual human activities, a large amount and volume of wastes from different sources that vary in composition and toxicity are generated. An important fraction of this waste is organic biodegradable material that has different characteristics that depend, fundamentally, on its origin: agricultural, forestry, agro-industrial, or urban. In general, the uncontrolled

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

dumping of this fraction into the soil is not advisable because its decomposition and / or the presence of hazardous pollutants can generate harmful effects that contaminate the soil, air and water. These biodegradable wastes have non-stabilized organic matter, so they present a high level of phytotoxicity and, frequently, a high load of pathogens, such as viruses, bacteria, fungi, and parasites, both for humans and for animals and plants and may become in a risk to the environment and health. In this way, the organic waste must be stabilized and conditioned reducing the possible effects previously mentioned before its disposal to the soil.

• Mesophilic phase: Mesophilic microorganisms proliferate when they feed on easily assimilable organic compounds, which produce an increase in temperature from values close to

Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent

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99

• Thermophilic phase: At temperatures above 40°C, the mesophilic activity drops, and the degradation begins a thermophilic stage reaching values of 60–70°C. This phase is crucial since temperatures of this magnitude destroy the pathogenic microorganisms and seeds of

• Cooling phase: Because easily degradable materials are consumed during the mesophilic phase and mainly in the thermophilic phase, there is a microbial activity decrease, and the

• Maturation phase: At this phase, complex secondary condensation and polymerization reactions occur, which results to the compost as the final product. It is necessary that this phase has the duration such that the material acquires the maturity and stability of an

The physical, chemical, and thermodynamic characteristics of the starting material determine the composting evolution, the process efficiency, and the compost quality. Some parameters

The composting matrix is a mass of solid particles that must contain enough pores and interstices to enable the development of the aerobic process, so that air circulates inside the mass providing an optimum concentration of oxygen, removing carbon dioxide and excessive moisture, and limiting excessive heat accumulation [5]. Sewage sludge cannot be composted alone due to its compactness and high water content, and bulking agents must be added to provide the structural support to create interparticle voids [6]. In general, organic materials such as agroforestry waste are used as bulking agents because, in addition to providing structure, they have the capacity to absorb water and facilitate the colonization and development of microbial populations [7]. The porosity or air spaces in the composting matrix can be estimated by different methods, and one of the most used is the measurement of free air space (FAS). The minimum values of FAS to ensure biological activity are around 30%, while values of 60–70% seem to be excessive to reach thermophilic temperatures in waste with low content of biodegradable organic matter [5, 8]. The mixture of bulking agent and sewage sludge improves FAS values for composting, although these agents also affect nutrient and moisture balances. Some research has been carried out to study the bulking agent:sludge ratio, as well as the type of bulking material and its particle size, in order to determine their influence on the sewage sludge composting (**Table 1**). The optimum bulking agent:sludge proportion will depend on factors such as process conditions (composting system, volume, time, etc.), origin of the bulking agent, type of bulking (fresh or recirculated), particle size, mixture conditions

temperature drops to environmental values returning to the mesophilic stage.

invasive plant species, so this ensures the sanitation of the compost.

must be taken into account before sewage sludge composting such as:

the ambient until reaching approximately 45°C.

organic amendment of agricultural application.

**1.1. Factors that affect the composting process**

*1.1.1. Particle size and free air space (FAS)*

(FAS, C/N ratio, moisture), etc.

Municipal wastewater treatment plants (WWTPs) produce different solid and semisolid residues during the treatment of the wastewater. Sludge is the semisolid waste generated during the primary (physical and/or chemical), the secondary (biological), and the tertiary (additional to secondary, often nutrient removal) treatment [1]. Sludge is by far the largest waste in volume, amount to about 11 million dry tons per year in the EU, which needs suitable and environmentally accepted management before the final disposal [2]. Since these residues are a source of nutrients and organic matter, it is reasonable to return them to the soil in optimal conditions to improve fertility and continue the natural cycle of nutrients. These organic wastes can undergo biodegradation processes, that is, the breaking of the most complex components into simple compounds through the action of living organisms. Likewise, the action of organisms converts simple molecules into more complex molecules of greater stability. Composting is one of the biological treatments that can be applied for the stabilization of municipal sewage sludge.

Composting is a controlled bio-oxidative process, in which a heterogeneous organic substrate undergoes a thermophilic stage and a transient release of phytotoxins, and produces final products: carbon dioxide, water, minerals and stabilized organic matter called compost (**Figure 1**) [3]. Due to the high microbial activity during the composting process, the temperature increases and accelerates the degradation and mineralization of the organic matter. Changes in temperature throughout the process allow differentiating four phases [4]:

**Figure 1.** Simple scheme of the composting process where a pile of organic material undergoes the transformation to compost by the action of aerobic microorganisms resulting in the production of heat, carbon dioxide, and water vapor.


#### **1.1. Factors that affect the composting process**

The physical, chemical, and thermodynamic characteristics of the starting material determine the composting evolution, the process efficiency, and the compost quality. Some parameters must be taken into account before sewage sludge composting such as:

#### *1.1.1. Particle size and free air space (FAS)*

dumping of this fraction into the soil is not advisable because its decomposition and / or the presence of hazardous pollutants can generate harmful effects that contaminate the soil, air and water. These biodegradable wastes have non-stabilized organic matter, so they present a high level of phytotoxicity and, frequently, a high load of pathogens, such as viruses, bacteria, fungi, and parasites, both for humans and for animals and plants and may become in a risk to the environment and health. In this way, the organic waste must be stabilized and conditioned

Municipal wastewater treatment plants (WWTPs) produce different solid and semisolid residues during the treatment of the wastewater. Sludge is the semisolid waste generated during the primary (physical and/or chemical), the secondary (biological), and the tertiary (additional to secondary, often nutrient removal) treatment [1]. Sludge is by far the largest waste in volume, amount to about 11 million dry tons per year in the EU, which needs suitable and environmentally accepted management before the final disposal [2]. Since these residues are a source of nutrients and organic matter, it is reasonable to return them to the soil in optimal conditions to improve fertility and continue the natural cycle of nutrients. These organic wastes can undergo biodegradation processes, that is, the breaking of the most complex components into simple compounds through the action of living organisms. Likewise, the action of organisms converts simple molecules into more complex molecules of greater stability. Composting is one of the biological treatments that can be applied for the stabilization of municipal sewage sludge.

Composting is a controlled bio-oxidative process, in which a heterogeneous organic substrate undergoes a thermophilic stage and a transient release of phytotoxins, and produces final products: carbon dioxide, water, minerals and stabilized organic matter called compost (**Figure 1**) [3]. Due to the high microbial activity during the composting process, the temperature increases and accelerates the degradation and mineralization of the organic matter.

**Figure 1.** Simple scheme of the composting process where a pile of organic material undergoes the transformation to compost by the action of aerobic microorganisms resulting in the production of heat, carbon dioxide, and water vapor.

Changes in temperature throughout the process allow differentiating four phases [4]:

reducing the possible effects previously mentioned before its disposal to the soil.

98 Sewage

The composting matrix is a mass of solid particles that must contain enough pores and interstices to enable the development of the aerobic process, so that air circulates inside the mass providing an optimum concentration of oxygen, removing carbon dioxide and excessive moisture, and limiting excessive heat accumulation [5]. Sewage sludge cannot be composted alone due to its compactness and high water content, and bulking agents must be added to provide the structural support to create interparticle voids [6]. In general, organic materials such as agroforestry waste are used as bulking agents because, in addition to providing structure, they have the capacity to absorb water and facilitate the colonization and development of microbial populations [7]. The porosity or air spaces in the composting matrix can be estimated by different methods, and one of the most used is the measurement of free air space (FAS). The minimum values of FAS to ensure biological activity are around 30%, while values of 60–70% seem to be excessive to reach thermophilic temperatures in waste with low content of biodegradable organic matter [5, 8]. The mixture of bulking agent and sewage sludge improves FAS values for composting, although these agents also affect nutrient and moisture balances. Some research has been carried out to study the bulking agent:sludge ratio, as well as the type of bulking material and its particle size, in order to determine their influence on the sewage sludge composting (**Table 1**). The optimum bulking agent:sludge proportion will depend on factors such as process conditions (composting system, volume, time, etc.), origin of the bulking agent, type of bulking (fresh or recirculated), particle size, mixture conditions (FAS, C/N ratio, moisture), etc.


sludge mixture. Even though, the optimal C/N ratio is conditioned by the nature of the bulking agent, so if the carbon is part of compounds that are difficult to break down, such as lignin,

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Sometimes, it is not possible to condition the waste in the most suitable way in industrial compost facilities. Nutrient levels, specifically the C/N ratio, may not reach the values considered optimal, so the process must be controlled to reduce nutrient losses as much as possible.

Once the parameters related to the nature of the substrate have been established and corrected, the process must be monitored and controlled within appropriate values for each

Temperature is one of the key factors that define the composting process in a way that a solid mixture reaches thermophilic temperatures that, sustained over time, make it possible to obtain compost free of parasites and weed seeds. The European Commission [16] proposes that temperatures must be maintained above 55°C for 15 days in windrow composting or 60°C for 1 week in in-vessel composting to achieve sanitation in biowaste. Excess temperature above 70°C is not convenient since it can cause the death of most microorganisms, delay colonization in later phases and, as a consequence, delay the degradation of the waste. Thus, the temperature during the process must be controlled to ensure that thermophilic temperatures are reached and sustained long enough to guarantee sanitation but not exceeding 70°C.

The maintenance of oxygen levels is a key factor for the development of an aerobic biological process. Oxygen concentration in the composting mass should not be less than 5% [17], since it would cause a succession toward anaerobic microorganisms and, therefore, toward undesirable fermentation processes and the generation of odors. To keep the oxygen levels in proper values during composting, the aeration of the mass must be controlled by forced and natural ventilation or turnings. In addition to supplying the oxygen demand for organic decomposition, aeration also favors the regulation of excess water and helps maintain the

In general, the choice of a composting system or technology in an industrial facility depends on several factors such as type and quantity of waste, economic considerations, legal aspects, location, environmental aspects and product quality, and others [17]. **Table 2** shows some of the most common systems, classified according to their relationship with the environment

Diaz et al. [14] established a differentiation of composting systems into two groups: "windrow," which refers to the accumulation of the material to be composted in more or less elon-

gated piles or rows, and "in vessel" where the material is confined within a reactor.

it will only be slowly available for microorganisms [15].

phase of composting, including temperature and oxygen.

*1.1.4. Temperature*

*1.1.5. Oxygen*

temperature at suitable values [5].

and the mixing or change of position.

**1.2. Composting systems**

**Table 1.** Some research references about the bulking agent, typology, and bulking agent:sludge ratio of the composting of sewage sludge.

According to Diaz et al. [14], the particle size depends on the physical nature of the waste, and sizes of 1–5 cm are suitable for materials that do not compact easily. Haug [5] states that wood chips about 5 cm in size are the most commonly used bulking agent. However, it is logical that the greater the volume of waste under treatment, the larger the size of the bulking agent, that is, in small-capacity research vessels, the use of small particles is recommended, but when industrial reactors or piles are considered, the particle size of bulking agent increases. Thus, an industrial pile with limited turnings will require large particle sizes of bulking agent to facilitate natural aeration.

#### *1.1.2. Moisture*

Since composting is a biodegradation process, the available water content must be sufficient to the physiological requirements of the microbiota. Water not only transports the soluble substances for microbial feeding but also eliminates the waste products resulting from cellular metabolism. The optimum moisture content at the beginning is around 55–60% for sewage sludge composting [5]. Higher moisture contents can cause water to fill the micropores of the mixture and hinder the oxygenation, while lower contents cause the decrease in biological activity. Sewage sludge moisture is corrected with bulking agent that absorbs water, as long as porous and unsaturated bulking agents are used.

#### *1.1.3. C/N ratio*

The microorganisms overall use about 30 parts of carbon for each part of nitrogen for their metabolism, carbon for energy source and component of cells and nitrogen for protein and nucleic acid synthesis. It is widely known that the composting matrix is more adequate when it has an initial C/N ratio between 25 and 35. High ratio, as in agroforestry waste with high carbon content, involves a decrease in biological activity due to a lack of nitrogen for the metabolism and, therefore, a slowing down of the composting process. Low C/N values, as in municipal sewage sludge, involve an excess of nitrogen that can be lost through volatilization or leaching. Bulking agents improve this ratio by providing organic carbon to the sewage sludge mixture. Even though, the optimal C/N ratio is conditioned by the nature of the bulking agent, so if the carbon is part of compounds that are difficult to break down, such as lignin, it will only be slowly available for microorganisms [15].

Sometimes, it is not possible to condition the waste in the most suitable way in industrial compost facilities. Nutrient levels, specifically the C/N ratio, may not reach the values considered optimal, so the process must be controlled to reduce nutrient losses as much as possible.

Once the parameters related to the nature of the substrate have been established and corrected, the process must be monitored and controlled within appropriate values for each phase of composting, including temperature and oxygen.

#### *1.1.4. Temperature*

Temperature is one of the key factors that define the composting process in a way that a solid mixture reaches thermophilic temperatures that, sustained over time, make it possible to obtain compost free of parasites and weed seeds. The European Commission [16] proposes that temperatures must be maintained above 55°C for 15 days in windrow composting or 60°C for 1 week in in-vessel composting to achieve sanitation in biowaste. Excess temperature above 70°C is not convenient since it can cause the death of most microorganisms, delay colonization in later phases and, as a consequence, delay the degradation of the waste. Thus, the temperature during the process must be controlled to ensure that thermophilic temperatures are reached and sustained long enough to guarantee sanitation but not exceeding 70°C.

#### *1.1.5. Oxygen*

According to Diaz et al. [14], the particle size depends on the physical nature of the waste, and sizes of 1–5 cm are suitable for materials that do not compact easily. Haug [5] states that wood chips about 5 cm in size are the most commonly used bulking agent. However, it is logical that the greater the volume of waste under treatment, the larger the size of the bulking agent, that is, in small-capacity research vessels, the use of small particles is recommended, but when industrial reactors or piles are considered, the particle size of bulking agent increases. Thus, an industrial pile with limited turnings will require large particle sizes of bulking agent to facilitate natural aeration.

**Table 1.** Some research references about the bulking agent, typology, and bulking agent:sludge ratio of the composting

>20 mm

1:0, 1:1, 1:2, 1:3 (w:w) 40 mm 35 kg reactors [10]

**Particle size Composting system Reference**

100 L reactors

47 L cylindrical reactors

piles [13]

[9]

[12]

Since composting is a biodegradation process, the available water content must be sufficient to the physiological requirements of the microbiota. Water not only transports the soluble substances for microbial feeding but also eliminates the waste products resulting from cellular metabolism. The optimum moisture content at the beginning is around 55–60% for sewage sludge composting [5]. Higher moisture contents can cause water to fill the micropores of the mixture and hinder the oxygenation, while lower contents cause the decrease in biological activity. Sewage sludge moisture is corrected with bulking agent that absorbs water, as long

The microorganisms overall use about 30 parts of carbon for each part of nitrogen for their metabolism, carbon for energy source and component of cells and nitrogen for protein and nucleic acid synthesis. It is widely known that the composting matrix is more adequate when it has an initial C/N ratio between 25 and 35. High ratio, as in agroforestry waste with high carbon content, involves a decrease in biological activity due to a lack of nitrogen for the metabolism and, therefore, a slowing down of the composting process. Low C/N values, as in municipal sewage sludge, involve an excess of nitrogen that can be lost through volatilization or leaching. Bulking agents improve this ratio by providing organic carbon to the sewage

*1.1.2. Moisture*

**Bulking agent Proportion** 

*Acacia* spp. trimming

of sewage sludge.

Recycled and fresh wooden

residues

100 Sewage

pallets

**(bulking:sludge)**

Wood chips 1:1, 2:1, 4:1 (v:v) 20, 10, 5 mm 4.5 L Dewar® vessels

3:1 (v:v) <20 mm and

Sawdust 1:1, 3:1 (v:v) 3 m3

Six different bulking agents 4:1 (v:v) 170 L reactors [11]

*1.1.3. C/N ratio*

as porous and unsaturated bulking agents are used.

The maintenance of oxygen levels is a key factor for the development of an aerobic biological process. Oxygen concentration in the composting mass should not be less than 5% [17], since it would cause a succession toward anaerobic microorganisms and, therefore, toward undesirable fermentation processes and the generation of odors. To keep the oxygen levels in proper values during composting, the aeration of the mass must be controlled by forced and natural ventilation or turnings. In addition to supplying the oxygen demand for organic decomposition, aeration also favors the regulation of excess water and helps maintain the temperature at suitable values [5].

#### **1.2. Composting systems**

In general, the choice of a composting system or technology in an industrial facility depends on several factors such as type and quantity of waste, economic considerations, legal aspects, location, environmental aspects and product quality, and others [17]. **Table 2** shows some of the most common systems, classified according to their relationship with the environment and the mixing or change of position.

Diaz et al. [14] established a differentiation of composting systems into two groups: "windrow," which refers to the accumulation of the material to be composted in more or less elongated piles or rows, and "in vessel" where the material is confined within a reactor.


nature of the initial wastewater and on the technical characteristics of the treatments carried out on wastewater [19]. These treatments concentrate the compounds present in the wastewater, so sewage sludge contains a wide variety of dissolved, settled and suspended substances. It is not only a source of organic matter, nitrogen, and phosphorus but also accumulates substances with potential contamination such as heavy metals, pathogens, and organic pollutants

Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent

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This study compiles the physicochemical analysis of 35 samples of sewage sludge from different WWTPs of municipalities in southern Galicia (Spain) with populations between 1000 and 35,000 inhabitants. These facilities have secondary treatments for the wastewater with subsequent dewatering of sewage sludge produced. **Figure 2** shows the different aspect of

All the parameters reflected those found in the literature for sewage sludge with similar characteristics (**Table 3**) [1, 20]. Moisture contents were lower than that observed by these authors; however, the values were homogenous despite being sampled from different WWTPs and seasonal periods. Sewage sludge composting requires moisture contents around 55–60% [5, 15] so the addition of bulking agents with low moisture allows not only reaching more adequate values of this parameter but also maintaining the structure and porosity of the mixture.

The content of organic matter is similar to the established ranges for untreated sludge despite they are sludge digested secondarily [1, 20]. Their high amount of organic substrates together with their high microbial load (inherent to their origin and the treatment with activated sludge) discourages direct disposal into the soil. Sewage sludge not enough stabilized incorporates pathogens and can cause rapid and uncontrolled biodegradation with the release of toxic substances. However, the high organic content makes these wastes suitable for treat-

These sewage sludge had a pH close to neutrality that was not incompatible with microbial development, although acidic pH affects the availability of heavy metals because heavy metal cations are generally most mobile under acid conditions [19]. The electrical conductivity presented an important variability, but harmful values for the microbial development were not reached.

Total carbon correlated positively with the content of organic matter (r = 0.76, p > 0.0001), but this parameter presented greater variability with high values in some of the samples indicating

**Figure 2.** Municipal sewage sludge from two WWTPs in the south of Galicia (Spain).

(personal hygiene products, pharmaceutics, etc.).

the sampled sewage sludge.

ment by biological techniques.

**Table 2.** Classification of the most commonly used composting systems [4, 14, 17].

From an operational point of view, it is considered that the composting process can be differentiated only in two stages. A bio-oxidative stage that corresponds mainly to the first two phases of the composting process, initial mesophilic phase and thermophilic phase, is characterized by high temperatures, elevated oxygen consumption, and the production of gaseous and liquid emissions [5]. This bio-oxidative stage is conditioned by the intensive organic matter decomposition and is usually developed with a specific technology and duration ranging from a few days to months in the industrial composting facilities. The second stage corresponds to the cooling and maturation phases. It usually lasts longer than the bio-oxidative stage although the dwell time is conditioned by the starting material characteristics and environmental and operating conditions of the facility [18]. The bio-oxidative stage is generally carried out using one of the technologies in **Table 2**, while the maturation period is carried out in piles or windrows, with more or less intervention depending on the idiosyncrasy of the facility or space available. In particular, most composting facilities that use "in-vessel" systems as technology involve the use of windrows to mature the compost [14]. A vessel system requires more investment but presents a greater control of the process: gas treatment, leachate collection system, data collection system of basic variables, watering, etc. The common dwell time in reactors or tunnels is around 14 days. Static reactors allow the monitoring of the process and, therefore, have been used in experimental research.

#### **1.3. Research objectives**

An industrial facility that periodically receives municipal sewage sludge should establish a working protocol which will optimize the composting process, ensuring the waste treatment under suitable conditions and time to obtain the highest quality compost. Obviously, it is crucial to know its initial characteristics since sewage sludge composition can be variable. For this reason, this work aims to (1) determine the inter- and intra-variability of municipal sewage sludge in physicochemical parameters, (2) establish the importance and effect of the bulking agent in the composting process of the municipal sewage sludge, and (3) check the reproducibility of the composting of sewage sludge from the same WWTP under the same conditions.

#### **2. Sewage sludge characterization and composting**

#### **2.1. Inter-sludge variability**

Municipal sewage sludge is characterized by its pasty or liquid consistency resulting from its high water content and small particle size. Physicochemical composition depends on the nature of the initial wastewater and on the technical characteristics of the treatments carried out on wastewater [19]. These treatments concentrate the compounds present in the wastewater, so sewage sludge contains a wide variety of dissolved, settled and suspended substances. It is not only a source of organic matter, nitrogen, and phosphorus but also accumulates substances with potential contamination such as heavy metals, pathogens, and organic pollutants (personal hygiene products, pharmaceutics, etc.).

This study compiles the physicochemical analysis of 35 samples of sewage sludge from different WWTPs of municipalities in southern Galicia (Spain) with populations between 1000 and 35,000 inhabitants. These facilities have secondary treatments for the wastewater with subsequent dewatering of sewage sludge produced. **Figure 2** shows the different aspect of the sampled sewage sludge.

From an operational point of view, it is considered that the composting process can be differentiated only in two stages. A bio-oxidative stage that corresponds mainly to the first two phases of the composting process, initial mesophilic phase and thermophilic phase, is characterized by high temperatures, elevated oxygen consumption, and the production of gaseous and liquid emissions [5]. This bio-oxidative stage is conditioned by the intensive organic matter decomposition and is usually developed with a specific technology and duration ranging from a few days to months in the industrial composting facilities. The second stage corresponds to the cooling and maturation phases. It usually lasts longer than the bio-oxidative stage although the dwell time is conditioned by the starting material characteristics and environmental and operating conditions of the facility [18]. The bio-oxidative stage is generally carried out using one of the technologies in **Table 2**, while the maturation period is carried out in piles or windrows, with more or less intervention depending on the idiosyncrasy of the facility or space available. In particular, most composting facilities that use "in-vessel" systems as technology involve the use of windrows to mature the compost [14]. A vessel system requires more investment but presents a greater control of the process: gas treatment, leachate collection system, data collection system of basic variables, watering, etc. The common dwell time in reactors or tunnels is around 14 days. Static reactors allow the monitoring of the pro-

**Open systems Semi-open systems Closed systems**

in closed buildings

Dynamics Turned piles/windrows/trenches Turned piles/windrows/trenches

**Table 2.** Classification of the most commonly used composting systems [4, 14, 17].

Piles/windrows with aerated semipermeable cover

Containers/aerated tunnels

Dynamic tunnels drums

An industrial facility that periodically receives municipal sewage sludge should establish a working protocol which will optimize the composting process, ensuring the waste treatment under suitable conditions and time to obtain the highest quality compost. Obviously, it is crucial to know its initial characteristics since sewage sludge composition can be variable. For this reason, this work aims to (1) determine the inter- and intra-variability of municipal sewage sludge in physicochemical parameters, (2) establish the importance and effect of the bulking agent in the composting process of the municipal sewage sludge, and (3) check the reproducibility of the composting of sewage sludge from the same WWTP under the same conditions.

Municipal sewage sludge is characterized by its pasty or liquid consistency resulting from its high water content and small particle size. Physicochemical composition depends on the

cess and, therefore, have been used in experimental research.

**2. Sewage sludge characterization and composting**

**1.3. Research objectives**

Statics Piles/windrows with passive or forced aeration

102 Sewage

**2.1. Inter-sludge variability**

All the parameters reflected those found in the literature for sewage sludge with similar characteristics (**Table 3**) [1, 20]. Moisture contents were lower than that observed by these authors; however, the values were homogenous despite being sampled from different WWTPs and seasonal periods. Sewage sludge composting requires moisture contents around 55–60% [5, 15] so the addition of bulking agents with low moisture allows not only reaching more adequate values of this parameter but also maintaining the structure and porosity of the mixture.

The content of organic matter is similar to the established ranges for untreated sludge despite they are sludge digested secondarily [1, 20]. Their high amount of organic substrates together with their high microbial load (inherent to their origin and the treatment with activated sludge) discourages direct disposal into the soil. Sewage sludge not enough stabilized incorporates pathogens and can cause rapid and uncontrolled biodegradation with the release of toxic substances. However, the high organic content makes these wastes suitable for treatment by biological techniques.

These sewage sludge had a pH close to neutrality that was not incompatible with microbial development, although acidic pH affects the availability of heavy metals because heavy metal cations are generally most mobile under acid conditions [19]. The electrical conductivity presented an important variability, but harmful values for the microbial development were not reached.

Total carbon correlated positively with the content of organic matter (r = 0.76, p > 0.0001), but this parameter presented greater variability with high values in some of the samples indicating

**Figure 2.** Municipal sewage sludge from two WWTPs in the south of Galicia (Spain).

#### 104 Sewage


**Table 3.** Physicochemical composition of 35 sewage sludge samples in Galicia, Spain.

an insufficient digestion. Since the ideal ratio for composting is around 20–30 parts of carbon per part of nitrogen, the addition of a carbonated material is necessary to avoid excessive loss of nitrogen. The addition of crushed wood is widely used in industrial facilities for sewage sludge improvement in several aspects: increase C/N ratio, increase in porosity, and moisture control, and with this, the distribution of the oxygen is necessary for the development of the aerobic microorganisms inherent to the composting process. However, the excessive use of bulking materials or co-substrates is not desirable in a treatment facility as the treatment of a larger volume of waste is prioritized in order to optimize costs and resources.

It is well known the harmful nature of sewage sludge when certain compounds, such as heavy metals, reach concentrations above a specific threshold. The most important toxic heavy metals include chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), and mercury (Hg). Concentrations of heavy metals in sewage sludge may vary widely, depending on the sludge origins. The content of heavy metals in wastewater, especially those originated in industrial zones and large metropolitan areas, can impose a serious problem since the sludge tends to accumulate heavy metals that exist in wastewater [21]. The mobility of trace metals, their bioavailability, and related eco-toxicity to plants depend strongly on their specific chemical forms or ways of binding [1]. There is a general consensus in the scientific literature that aerobic composting processes increase the complexation of heavy metals in organic waste residuals and that metals are strongly bound to the compost matrix and organic matter, limiting their solubility and potential bioavailability in soil [22]. All heavy metals analyzed (**Figure 3**) showed a wide variability with values, without considering the outliers, of 18 times in copper, 20 times in lead, and 15 times in mercury, for example. However, these values are typical in sewage sludge [1].

heavy metals in the wastewater. Sewage sludge samples analyzed in this study came from municipalities with different populations, from 1000 to 35,000 inhabitants, although no correlation was found between the population and the contents of heavy metals. The atypical values observed in Cr, Cu, Hg, Ni, and Zn can be attributed to point pollution, and it is considered that the sewage sludge do not present a high pollutant load. However, organic pollutants that are common in wastewater (antibiotics, hydrocarbons, detergents, etc.) have not been analyzed in this study. Aerobic composting has been extensively documented to reduce

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105

To determine the variability of the physicochemical composition of the same sewage sludge, ten samples from the same WWTP were analyzed in a period of 5 years (**Table 4**). Although variability was observed in the parameters analyzed, this was lower than the inter-sludge

the concentrations of organic compounds via biological degradation [24–26].

**Figure 3.** Distribution of heavy metals in sludge samples as revealed in the box plot diagram.

**2.2. Intra-sludge variability**

The content of heavy metals in sewage sludge is frequently related to industrial density as a consequence of discharges to public sanitation. However, diffuse sources such as urban runoff and small household operations can contribute to contaminated discharges from an imposed residential area [23]. Also, high population agglomerations usually cause higher contents of

Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent http://dx.doi.org/10.5772/intechopen.75130 105

**Figure 3.** Distribution of heavy metals in sludge samples as revealed in the box plot diagram.

heavy metals in the wastewater. Sewage sludge samples analyzed in this study came from municipalities with different populations, from 1000 to 35,000 inhabitants, although no correlation was found between the population and the contents of heavy metals. The atypical values observed in Cr, Cu, Hg, Ni, and Zn can be attributed to point pollution, and it is considered that the sewage sludge do not present a high pollutant load. However, organic pollutants that are common in wastewater (antibiotics, hydrocarbons, detergents, etc.) have not been analyzed in this study. Aerobic composting has been extensively documented to reduce the concentrations of organic compounds via biological degradation [24–26].

#### **2.2. Intra-sludge variability**

an insufficient digestion. Since the ideal ratio for composting is around 20–30 parts of carbon per part of nitrogen, the addition of a carbonated material is necessary to avoid excessive loss of nitrogen. The addition of crushed wood is widely used in industrial facilities for sewage sludge improvement in several aspects: increase C/N ratio, increase in porosity, and moisture control, and with this, the distribution of the oxygen is necessary for the development of the aerobic microorganisms inherent to the composting process. However, the excessive use of bulking materials or co-substrates is not desirable in a treatment facility as the treatment of a

**Mean Median Percentile 5–95%**

It is well known the harmful nature of sewage sludge when certain compounds, such as heavy metals, reach concentrations above a specific threshold. The most important toxic heavy metals include chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), and mercury (Hg). Concentrations of heavy metals in sewage sludge may vary widely, depending on the sludge origins. The content of heavy metals in wastewater, especially those originated in industrial zones and large metropolitan areas, can impose a serious problem since the sludge tends to accumulate heavy metals that exist in wastewater [21]. The mobility of trace metals, their bioavailability, and related eco-toxicity to plants depend strongly on their specific chemical forms or ways of binding [1]. There is a general consensus in the scientific literature that aerobic composting processes increase the complexation of heavy metals in organic waste residuals and that metals are strongly bound to the compost matrix and organic matter, limiting their solubility and potential bioavailability in soil [22]. All heavy metals analyzed (**Figure 3**) showed a wide variability with values, without considering the outliers, of 18 times in copper, 20 times in lead, and 15 times in mercury, for example. However, these values

The content of heavy metals in sewage sludge is frequently related to industrial density as a consequence of discharges to public sanitation. However, diffuse sources such as urban runoff and small household operations can contribute to contaminated discharges from an imposed residential area [23]. Also, high population agglomerations usually cause higher contents of

larger volume of waste is prioritized in order to optimize costs and resources.

Moisture (%) 84.0 85.3 76.8–87.4 Organic matter (%) 71.7 73.6 55.7–81.5 pH 6.8 6.8 5.9–7.9 Electrical conductivity (mS cm−1) 0.63 0.59 0.09–1.41 Total carbon (% dw) 35.8 36.1 28.1–40.1 Total nitrogen (% dw) 5.23 5.5 3.3–6.7 C/N ratio 7.2 6.5 5.7–12.2

(% dw) 3.5 3.6 1.6–5.1

**Table 3.** Physicochemical composition of 35 sewage sludge samples in Galicia, Spain.

(g kg−1 dw) 7.3 6.0 0.7–19.5

are typical in sewage sludge [1].

P2 O5

104 Sewage

N-NH<sup>4</sup> +

> To determine the variability of the physicochemical composition of the same sewage sludge, ten samples from the same WWTP were analyzed in a period of 5 years (**Table 4**). Although variability was observed in the parameters analyzed, this was lower than the inter-sludge


development of sewage sludge composting, taking as reference to the self-heating capacity of the waste and the capacity to maintain the thermophilic conditions. As sewage sludge is obtained after secondary treatment, some of the more readily available compounds have already been consumed, so the biodegradation process may be weakened or slowed down. Composting must guarantee maximum sanitization reaching high temperatures and presenting an extended thermophilic phase. In this way, organic matter is stabilized, and the content

Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent

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Therefore, a composting test was carried out on 12 static reactors of 30 L each one with aeration control using three different proportions in volume 3:1, 2:1, and 1:1 and bulking:sludge in triplicate (**Figure 4**). Sewage sludge characterized in **Table 4** was used. As a bulking agent, crushed wood with a size between 0 and 10 mm was used. This particle size has been the ideal one for a pasty residue and for the volume and characteristics of the reactors according to previous experiences. The main characteristics of this bulking material were moisture 32% and organic matter 90%. Composting in reactors facilitates the control of temperature (maximum 60°C), oxygen levels (minimum 5%) and the time and aeration regime (continuous and depending on the tracking parameters). Likewise, this system allows exhaust gases to be directed to a biofilter for odor control and the collection of

From an empirical point of view, the sludge and bulking mixture were done with difficulty due to the pasty character of this waste which tended to form clumps. In particular, the 1:1 ratio was the most complex mixture to make because some areas were not structured enough and converted the mixture into a dense mass that affected the compaction inside the reactor and produced possible anoxic areas. In contrast, the 3:1 ratio had a porous and looser structure, and most of the sludge was surrounded by wood particles. Oxygen levels remained over 8% in all proportions. **Figure 5** shows how the microbial activity and therefore the temperature responded to the conditions of the experiment. The municipal sewage sludge presented the adequate nutritional conditions for microbial growth according to what was observed in the evolution of temperature. This evolution was significantly different depending on the proportion of bulking agent (p < 0.0001). Although the lowest proportions experienced quick

**Figure 4.** System of 12 composting reactors of 30 L, each one inside a wooden box for the maintenance of adiabatic

conditions (left) and mixture of bulking agent with sewage sludge in 3:1 proportion in volume (right).

of pathogens inherent in wastewater is reduced or eliminated.

leachates.

**Table 4.** Analysis of physicochemical parameters of 10 sludge samples from the same WWTP for 5 years.

variability. It is important to highlight the greater homogeneity in the C/N ratio and moisture, while organic matter, total carbon, ammonium, and electrical conductivity had important oscillations. As the WWTP did not have operational alterations in the treatment process over the sampling time, it is assumed that the variability is a consequence of the input wastewater. Heavy rainfall can dilute wastewater, while water consumption in municipalities tends to decrease in the rainy season. However, no appreciable seasonal differences were found in the parameters studied, with more sampling being necessary to corroborate this observation.

The distribution of heavy metals corresponds with the lower quartile (values lower than the median) of inter-sludge heavy metal analysis, so it is a waste with low degree of contamination. Although the WWTP treats the wastewater of 25,000 inhabitants, the level of industrialization of the municipality is low, and the services sector dedicated to tourism is predominant, so the presence of heavy metals in the wastewater corresponds to domestic and residential operations with low inorganic pollution.

In industrial composting facilities, the sewage sludge is subjected to preconditioning which generally consists of mixing with bulking agents and other co-substrates and which must be based on the composition of the input waste. As observed, this composition is variable, and therefore it is necessary to know if this variability influences the development of the process in a significant way.

#### **2.3. Bulking agent proportion**

Using crushed wood it is possible to improve both the physical and chemical parameters of sewage sludge, so that the distribution of oxygen and macronutrients are more suitable for aerobic microbial growth necessary for the process. For the determination of the balance between bulking agent and sewage sludge, mathematical formulas or proportional rules can be used trying to reach the desired humidity, FAS, or C/N ratio [5, 17, 27]. The objective of this experience was to determine the proportion of bulking agent most suitable for the development of sewage sludge composting, taking as reference to the self-heating capacity of the waste and the capacity to maintain the thermophilic conditions. As sewage sludge is obtained after secondary treatment, some of the more readily available compounds have already been consumed, so the biodegradation process may be weakened or slowed down. Composting must guarantee maximum sanitization reaching high temperatures and presenting an extended thermophilic phase. In this way, organic matter is stabilized, and the content of pathogens inherent in wastewater is reduced or eliminated.

Therefore, a composting test was carried out on 12 static reactors of 30 L each one with aeration control using three different proportions in volume 3:1, 2:1, and 1:1 and bulking:sludge in triplicate (**Figure 4**). Sewage sludge characterized in **Table 4** was used. As a bulking agent, crushed wood with a size between 0 and 10 mm was used. This particle size has been the ideal one for a pasty residue and for the volume and characteristics of the reactors according to previous experiences. The main characteristics of this bulking material were moisture 32% and organic matter 90%. Composting in reactors facilitates the control of temperature (maximum 60°C), oxygen levels (minimum 5%) and the time and aeration regime (continuous and depending on the tracking parameters). Likewise, this system allows exhaust gases to be directed to a biofilter for odor control and the collection of leachates.

variability. It is important to highlight the greater homogeneity in the C/N ratio and moisture, while organic matter, total carbon, ammonium, and electrical conductivity had important oscillations. As the WWTP did not have operational alterations in the treatment process over the sampling time, it is assumed that the variability is a consequence of the input wastewater. Heavy rainfall can dilute wastewater, while water consumption in municipalities tends to decrease in the rainy season. However, no appreciable seasonal differences were found in the parameters studied, with more sampling being necessary to corroborate this observation. The distribution of heavy metals corresponds with the lower quartile (values lower than the median) of inter-sludge heavy metal analysis, so it is a waste with low degree of contamination. Although the WWTP treats the wastewater of 25,000 inhabitants, the level of industrialization of the municipality is low, and the services sector dedicated to tourism is predominant, so the presence of heavy metals in the wastewater corresponds to domestic and residential

**Table 4.** Analysis of physicochemical parameters of 10 sludge samples from the same WWTP for 5 years.

Moisture (%) 85.5 84–87 Cd (mg kg−1 dw) 1.3 1.0–2.1 Organic matter (%) 75.0 71–79 Cr (mg kg−1 dw) 40.6 27.1–48.8 pH 6.8 6.2–7.4 Cu (mg kg−1 dw) 330 244–402 Electrical conductivity (mS cm−1) 0.55 0.1–1.1 Ni (mg kg−1 dw) 20.9 14.9–27.7 Total carbon (% dw) 36.3 33–40 Pb (mg kg−1 dw) 89.8 65–122 Total nitrogen (% dw) 5.75 5.2–6.6 Zn (mg kg−1 dw) 502 443–590 C/N ratio 6.3 5.8–6.8 Hg (mg kg−1 dw) 0.48 0.3–0.8

**Mean Percentile 5–95% Mean Percentile 5–95%**

In industrial composting facilities, the sewage sludge is subjected to preconditioning which generally consists of mixing with bulking agents and other co-substrates and which must be based on the composition of the input waste. As observed, this composition is variable, and therefore it is necessary to know if this variability influences the development of the process

Using crushed wood it is possible to improve both the physical and chemical parameters of sewage sludge, so that the distribution of oxygen and macronutrients are more suitable for aerobic microbial growth necessary for the process. For the determination of the balance between bulking agent and sewage sludge, mathematical formulas or proportional rules can be used trying to reach the desired humidity, FAS, or C/N ratio [5, 17, 27]. The objective of this experience was to determine the proportion of bulking agent most suitable for the

operations with low inorganic pollution.

(% dw) 4.6 3.9–5.3

(g kg−1 dw) 5.5 0.4–13

in a significant way.

P2 O5

106 Sewage

N-NH<sup>4</sup> +

**2.3. Bulking agent proportion**

From an empirical point of view, the sludge and bulking mixture were done with difficulty due to the pasty character of this waste which tended to form clumps. In particular, the 1:1 ratio was the most complex mixture to make because some areas were not structured enough and converted the mixture into a dense mass that affected the compaction inside the reactor and produced possible anoxic areas. In contrast, the 3:1 ratio had a porous and looser structure, and most of the sludge was surrounded by wood particles. Oxygen levels remained over 8% in all proportions. **Figure 5** shows how the microbial activity and therefore the temperature responded to the conditions of the experiment. The municipal sewage sludge presented the adequate nutritional conditions for microbial growth according to what was observed in the evolution of temperature. This evolution was significantly different depending on the proportion of bulking agent (p < 0.0001). Although the lowest proportions experienced quick

**Figure 4.** System of 12 composting reactors of 30 L, each one inside a wooden box for the maintenance of adiabatic conditions (left) and mixture of bulking agent with sewage sludge in 3:1 proportion in volume (right).

was a quick thermal decline after the thermophilic phase which, added to the slight loss of organic matter, indicates that the more porous structure of the mass caused a rapid cooling

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109

The bulking:sludge ratio more suitable from the point of view of temperature, in the short term considered in this experiment, was the ratio 2:1, although its initial moisture content was not considered optimal and its C/N ratio could facilitate the loss of nitrogen. This proportion allows greater treatment of sewage sludge per unit volume than the 3:1 ratio in an industrial

The following experiment consists of the comparison of composting experiences on a larger scale that have a purpose to verify the reproducibility of the sewage sludge process with a 2:1 ratio (bulking:sludge). In this way, the same sewage sludge as in sections 2.2. and 2.3. (**Table 4**) was sampled six times. Crushed wood was used as a bulking agent, but the particle size was adapted to reach a 30% FAS in the mixture [5] and to the highest reactor volume (600 L), considering wood particles between 0 and 30 mm as optimal. Each mixture bulking:sludge was introduced into the reactor (**Figure 7**), the temperature and oxygen levels were controlled by forced aeration, and processes were finished when the temperature dropped to environmental

Compared with the previous experience, the initial C/N varied remarkably (8–16), especially due to the wide fluctuations of the initial carbon. Also, moisture contents were higher than in the previous experiment. Regarding the development of the process (**Figure 8**), the evolution of the temperature was significantly different (p < 0.001), and two groups can be differentiated: a group of reduced thermophilic phase constituted of sewage sludge reactors 1, 2, and 3 (SS1, SS2, and SS3) and a group of prolonged thermophilic phase constituted of sewage sludge reactors 4, 5, and 6 (SS4, SS5, and SS6). Notable differences were observed in terms of high-temperature conditions: from 3 days under thermophilic conditions in SS1 to 18 days in SS6. Thus, it was observed that the higher the C/N ratio, the greater the capacity to maintain the thermophilic conditions (SS5 and SS6), while the influence of this

**Figure 7.** Composting reactor of 600 L equipped with a fan, recorder, and control of process parameters and biofilter (left) and colonized mixture of bulking agent with sewage sludge in 2:1 proportion in volume after process time (right).

that prevented the support of temperature and biodegradation at an intensive level.

treatment facility.

**2.4. Composting reproducibility**

values after the thermophilic phase.

**Figure 5.** Evolution of the average temperature of the three proportions bulking agent:sludge inside the 30 L composting reactors.

self-heating, the 3:1 ratio was possibly slowed down as a result of the higher content of more recalcitrant carbonated substances that were difficult to break down. The maintenance period of thermophilic temperatures was higher in the 2:1 ratio (4 days), followed by 3:1 (3 days), and finally the 1:1 ratio (1.5 days). It is logical that the higher the content of sewage sludge in the mixture, the greater the content of substances that are easier to break down and the greater the amount of treated sewage sludge per unit volume. However, the 1:1 ratio maintained lower microbial activity that, in line with what was observed during mixing, can be a consequence of its greater compaction and the presence of preferential aeration channels in the mass that prevent a correct distribution of air. After reaching temperatures lower than 35°C, the process was completed, and a high colonization of fungi was observed in some reactors (**Figure 6**). The mass balance after 9 days of the process showed organic matter losses of 10% (2:1), 4.5% (3:1), and 1.6% (1:1). Although 3:1 ratio reached the maximum temperature, there

**Figure 6.** Development of fungi in reactors with a 2:1 ratio (left) and emptying of a reactor with a 3:1 ratio (right).

was a quick thermal decline after the thermophilic phase which, added to the slight loss of organic matter, indicates that the more porous structure of the mass caused a rapid cooling that prevented the support of temperature and biodegradation at an intensive level.

The bulking:sludge ratio more suitable from the point of view of temperature, in the short term considered in this experiment, was the ratio 2:1, although its initial moisture content was not considered optimal and its C/N ratio could facilitate the loss of nitrogen. This proportion allows greater treatment of sewage sludge per unit volume than the 3:1 ratio in an industrial treatment facility.

#### **2.4. Composting reproducibility**

self-heating, the 3:1 ratio was possibly slowed down as a result of the higher content of more recalcitrant carbonated substances that were difficult to break down. The maintenance period of thermophilic temperatures was higher in the 2:1 ratio (4 days), followed by 3:1 (3 days), and finally the 1:1 ratio (1.5 days). It is logical that the higher the content of sewage sludge in the mixture, the greater the content of substances that are easier to break down and the greater the amount of treated sewage sludge per unit volume. However, the 1:1 ratio maintained lower microbial activity that, in line with what was observed during mixing, can be a consequence of its greater compaction and the presence of preferential aeration channels in the mass that prevent a correct distribution of air. After reaching temperatures lower than 35°C, the process was completed, and a high colonization of fungi was observed in some reactors (**Figure 6**). The mass balance after 9 days of the process showed organic matter losses of 10% (2:1), 4.5% (3:1), and 1.6% (1:1). Although 3:1 ratio reached the maximum temperature, there

**Figure 5.** Evolution of the average temperature of the three proportions bulking agent:sludge inside the 30 L composting reactors.

108 Sewage

**Figure 6.** Development of fungi in reactors with a 2:1 ratio (left) and emptying of a reactor with a 3:1 ratio (right).

The following experiment consists of the comparison of composting experiences on a larger scale that have a purpose to verify the reproducibility of the sewage sludge process with a 2:1 ratio (bulking:sludge). In this way, the same sewage sludge as in sections 2.2. and 2.3. (**Table 4**) was sampled six times. Crushed wood was used as a bulking agent, but the particle size was adapted to reach a 30% FAS in the mixture [5] and to the highest reactor volume (600 L), considering wood particles between 0 and 30 mm as optimal. Each mixture bulking:sludge was introduced into the reactor (**Figure 7**), the temperature and oxygen levels were controlled by forced aeration, and processes were finished when the temperature dropped to environmental values after the thermophilic phase.

Compared with the previous experience, the initial C/N varied remarkably (8–16), especially due to the wide fluctuations of the initial carbon. Also, moisture contents were higher than in the previous experiment. Regarding the development of the process (**Figure 8**), the evolution of the temperature was significantly different (p < 0.001), and two groups can be differentiated: a group of reduced thermophilic phase constituted of sewage sludge reactors 1, 2, and 3 (SS1, SS2, and SS3) and a group of prolonged thermophilic phase constituted of sewage sludge reactors 4, 5, and 6 (SS4, SS5, and SS6). Notable differences were observed in terms of high-temperature conditions: from 3 days under thermophilic conditions in SS1 to 18 days in SS6. Thus, it was observed that the higher the C/N ratio, the greater the capacity to maintain the thermophilic conditions (SS5 and SS6), while the influence of this

**Figure 7.** Composting reactor of 600 L equipped with a fan, recorder, and control of process parameters and biofilter (left) and colonized mixture of bulking agent with sewage sludge in 2:1 proportion in volume after process time (right).

**Figure 8.** Evolution of temperature during the reactor phase of sewage sludge from the same WWTP at different sampling periods mixed with bulking agent.

parameter on the initial self-heating capacity was not observed. However, the time to reach thermophilic values slowed down with high moisture contents (> 70% moisture), contrary to the experience in 30 L reactors.

As a result of the research, it can be extrapolated that a ratio of 2:1 (bulking:sludge) does not reach the ideal moisture for the composting process, but if the C/N ratio exceeds 10 and the moisture is below 70%, the maintenance of the thermophilic conditions seems to be prolonged. In an industrial compost facility, it is very complicated to establish an ideal mixing protocol for a specific sewage sludge since the variability of the input material causes important variations in the development of the composting process.

#### **2.5. Compost analysis**

After emptying the reactors from the reproducibility test, the pre-composted materials were turned and kept in piles for 90 days to mature, and next, compost analyses were performed (**Table 5**). Variability can be observed in the general characteristics established by the legislation on fertilizer products [28] and other important parameters of stability and maturation of compost [29, 30].

The Spanish legislation on compost, Royal Decree 506/2013 of 28 June on fertilizers [28], classifies compost into three categories according to the heavy metal content: classes A, B, and C. The content of Cd, Ni, Pb, Zn, and Cu assumes that all composts are classified as class B. So, low inorganic pollution in input sewage sludge allows meeting the quality criteria for the use of compost as an organic amendment. Although the sewage sludge evolved differently inside the reactor, maturation in a pile for 90 days seems to assimilate the composition of the composts.

**Table 5.** Maturity and stability parameters in sewage sludge composts from the same WWTP sampled in different times

Cd (mg kg−1 dw) 0.8–1.6 0.7 2 3 Cr (mg kg−1 dw) 38–52 70 250 300 Cu (mg kg−1 dw) 240–300 70 300 400 Ni (mg kg−1 dw) 21–26 25 90 100 Pb (mg kg−1 dw) 54–84 45 150 200 Zn (mg kg−1 dw) 300–480 200 500 1000 Hg (mg kg−1 dw) 0.3–0.4 0.4 1.5 2.5

**Range Spanish Fertilizers Law [28]**

http://dx.doi.org/10.5772/intechopen.75130

111

Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent

*Class A Class B Class C*

Moisture (%) 51–66 < 40 Organic matter (%) 66–75 > 35 pH 5.4–6.2 — Electrical conductivity (mS cm−1) 0.9–1.2 — Total carbon (% dw) 33–38 — Total nitrogen (% dw) 2.9–3.4 — C/N ratio 10–14 < 20

 (% dw) 3.3–3.5 — Basal respiration (mg kg SV h−1) 100–330 — Self-heating test IV–V — Germination index (%) 96–108 — *Salmonella* spp. (in 25 g) Absence Absence *Escherichia coli* (ufc/g) <10–800 <1000

Maximum values allowed in the Spanish fertilizers law for compost are included

and composted in 2:1 ratio bulking:sludge in static reactor and followed by pile maturation.

The development of cities and the centralization of sanitation services mean that the sewage sludge produced in wastewater treatment plants has a growing presence in our society.

**3. Conclusions**

P2 O5

It is important to note that organic matter is high in some samples as a consequence of the short periods under thermophilic conditions and that the finest fraction of the bulking agent becomes part of the compost after sieving, increasing this parameter. However, the organic matter is reasonably stabilized with low respiratory activities (less than mg O2 g−1SV h−1) and poor self-heating of the compost with maximum rating for this test (classes IV and V). Likewise, the germination indexes were high (> 80%) which allows the use of compost without harming the plant growth. The pathogens were within the values for the use of compost, and all experiences allowed sanitation although the group of reduced thermophilic phase (SS1, SS2, and SS3) presented the highest values of *Escherichia coli*.

Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent http://dx.doi.org/10.5772/intechopen.75130 111


**Table 5.** Maturity and stability parameters in sewage sludge composts from the same WWTP sampled in different times and composted in 2:1 ratio bulking:sludge in static reactor and followed by pile maturation.

The Spanish legislation on compost, Royal Decree 506/2013 of 28 June on fertilizers [28], classifies compost into three categories according to the heavy metal content: classes A, B, and C. The content of Cd, Ni, Pb, Zn, and Cu assumes that all composts are classified as class B. So, low inorganic pollution in input sewage sludge allows meeting the quality criteria for the use of compost as an organic amendment. Although the sewage sludge evolved differently inside the reactor, maturation in a pile for 90 days seems to assimilate the composition of the composts.

#### **3. Conclusions**

parameter on the initial self-heating capacity was not observed. However, the time to reach thermophilic values slowed down with high moisture contents (> 70% moisture), contrary

**Figure 8.** Evolution of temperature during the reactor phase of sewage sludge from the same WWTP at different

As a result of the research, it can be extrapolated that a ratio of 2:1 (bulking:sludge) does not reach the ideal moisture for the composting process, but if the C/N ratio exceeds 10 and the moisture is below 70%, the maintenance of the thermophilic conditions seems to be prolonged. In an industrial compost facility, it is very complicated to establish an ideal mixing protocol for a specific sewage sludge since the variability of the input material causes important variations

After emptying the reactors from the reproducibility test, the pre-composted materials were turned and kept in piles for 90 days to mature, and next, compost analyses were performed (**Table 5**). Variability can be observed in the general characteristics established by the legislation on fertilizer products [28] and other important parameters of stability and maturation of

It is important to note that organic matter is high in some samples as a consequence of the short periods under thermophilic conditions and that the finest fraction of the bulking agent becomes part of the compost after sieving, increasing this parameter. However, the organic

and poor self-heating of the compost with maximum rating for this test (classes IV and V). Likewise, the germination indexes were high (> 80%) which allows the use of compost without harming the plant growth. The pathogens were within the values for the use of compost, and all experiences allowed sanitation although the group of reduced thermophilic phase

g−1SV h−1)

matter is reasonably stabilized with low respiratory activities (less than mg O2

(SS1, SS2, and SS3) presented the highest values of *Escherichia coli*.

to the experience in 30 L reactors.

sampling periods mixed with bulking agent.

110 Sewage

**2.5. Compost analysis**

compost [29, 30].

in the development of the composting process.

The development of cities and the centralization of sanitation services mean that the sewage sludge produced in wastewater treatment plants has a growing presence in our society. Composting is a viable alternative for sludge management, but initial characteristics of the waste must be determined for process optimization. The municipal sewage sludge presents high inter- and intra-variability in key parameters for the evolution of the composting process such as moisture and the C/N ratio. The levels of heavy metals in specific samples of sewage sludge are not useful information if there are no periodical analyses to detect point pollution or seasonal changes. The addition of bulking agent is necessary for the development of the composting process, but its size and proportion must be adapted to the waste composition, the composting system used, and the volume of treatment. The variability in sewage sludge composition makes it difficult to establish treatment protocols in industrial composting facilities, although the establishment of minimum process conditions is necessary, for which the use of a minimum proportion of bulking agent:sludge 2:1 in volume is recommended. Despite the different evolution of the composting process, if the initial sewage sludge presents average composition, the compost achieves adequate quality parameters.

[5] Haug RT. The Practical Handbook of Compost Engineering. Boca Raton: Lewis Pub-

Municipal Sewage Sludge Variability: Biodegradation through Composting with Bulking Agent

http://dx.doi.org/10.5772/intechopen.75130

113

[6] Eftoda G, McCartney D. Determining the critical bulking agent requirement for municipal biosolids composting. Compost Science & Utilization. 2004;**12**(3):208-218. DOI: 10.1080/

[7] Villar I, Alves D, Mato S, Romero XM, Varela B. Decentralized Composting of Organic Waste in a European Rural Region: A Case Study in Allariz (Galicia, Spain). In: Mihai F-C, editor. Solid Waste Management in Rural Areas. InTech; pp. 53-79. DOI: 10.5772/

[8] Ruggieri L, Gea T, Artola A, Sánchez A. Air filled porosity measurements by air pycnometry in the composting process: A review and a correlation analysis. Bioresource

[9] Gea T, Barrena R, Artola A, Sánchez A. Optimal bulking agent particle size and usage for heat retention and disinfection in domestic wastewater sludge composting. Waste

[10] Yañez R, Alonso JL, Díaz MJ. Influence of bulking agent on sewage sludge composting process. Bioresource Technology. 2009;**100**:5827-5833. DOI: 10.1016/j.biortech.2009.05.073

[11] Doublet J, Francou C, Poitrenaud M, Houot S. Influence of bulking agents on organic matter evolution during sewage sludge composting; consequences on compost organic matter stability and N availability. Bioresource Technology. 2011;**102**:1298-1307. DOI:

[12] Huet J, Druilhe C, Trémier A, Benoist JC, Debenest G. The impact of compaction, moisture content, particle size and type of bulking agent on initial physical properties of sludgebulking agent mixtures before composting. Bioresource Technology. 2012;**114**:428-436.

[13] Banegas V, Moreno JL, Moreno JI, García C, León G, Hernández T. Composting anaerobic and aerobic sewage sludges using two proportions of sawdust. Waste Management.

[14] Diaz LF, Savage GM, Eggerth LL, Chiumenti A. Systems used in composting. In:

[15] Diaz LF, Savage GM. Factors that affect the process. In: Diaz LF, De Bertoldi M, Bidlingmaier W, Stentinford E, editors. Compost Science and Technology. Waste Management Series.

[16] European Commission. Working document: Biological treatment of biowaste, 2nd draft.

[17] Epstein E. Industrial composting. Environmental Engineering and Facilities Manage-

Technology. 2009;**100**(10):2655-2666. DOI: 10.1016/j.biortech.2008.12.049

Management. 2007;**27**:1108-1116. DOI: 10.1016/j.wasman.2006.07.005

lishers; 1993

1065657X.2004.10702185

10.1016/j.biortech.2010.08.065

DOI: 10.1016/j.biortech.2012.03.031

2007;**27**:1317-1327. DOI: 10.1016/j.wasman.2006.09.008

Compost Science and Technology. 2007. p. 67-87

Amsterdam: Elsevier; 2007. vol. 8. pp. 49-65

ment. Taylor Francis Group LLC. 2011

Dir Gen Environ. 2001:22-22

intechopen.69555

#### **Acknowledgements**

The authors thank the research support services of the University of Vigo (CACTI) for the carbon, nitrogen, and heavy metal analysis.

#### **Author details**

David Alves Comesaña, Iria Villar Comesaña\* and Salustiano Mato de la Iglesia

\*Address all correspondence to: iriavillar@uvigo.es

Department of Ecology and Animal Biology, University of Vigo, Vigo, Spain

#### **References**


[5] Haug RT. The Practical Handbook of Compost Engineering. Boca Raton: Lewis Publishers; 1993

Composting is a viable alternative for sludge management, but initial characteristics of the waste must be determined for process optimization. The municipal sewage sludge presents high inter- and intra-variability in key parameters for the evolution of the composting process such as moisture and the C/N ratio. The levels of heavy metals in specific samples of sewage sludge are not useful information if there are no periodical analyses to detect point pollution or seasonal changes. The addition of bulking agent is necessary for the development of the composting process, but its size and proportion must be adapted to the waste composition, the composting system used, and the volume of treatment. The variability in sewage sludge composition makes it difficult to establish treatment protocols in industrial composting facilities, although the establishment of minimum process conditions is necessary, for which the use of a minimum proportion of bulking agent:sludge 2:1 in volume is recommended. Despite the different evolution of the composting process, if the initial sewage sludge presents aver-

The authors thank the research support services of the University of Vigo (CACTI) for the

[1] Fytili D, Zabaniotou A. Utilization of sewage sludge in EU application of old and new methods—A review. Renewable and Sustainable Energy Reviews. 2008;**12**(1):116-140.

[2] Kelessidis A, Stasinakis AS. Comparative study of the methods used for treatment and final disposal of sewage sludge in European countries. Waste Management.

[3] Zucconi F, De Bertoldi M. Compost specifications for the production and characterization of compost from municipal solid waste. In: De Bertoldi M, Ferranti MP, L'Hermite P, Zucconi F, editors. Production, Quality and Use. London: Elsevier Applied Science

[4] Moreno J, Moral R. Compostaje. Madrid: Ediciones Mundi-Prensa; 2008. 570 p

David Alves Comesaña, Iria Villar Comesaña\* and Salustiano Mato de la Iglesia

Department of Ecology and Animal Biology, University of Vigo, Vigo, Spain

2012;**32**(6):1186-1195. DOI: 10.1016/j.wasman.2012.01.012

age composition, the compost achieves adequate quality parameters.

**Acknowledgements**

112 Sewage

**Author details**

**References**

carbon, nitrogen, and heavy metal analysis.

\*Address all correspondence to: iriavillar@uvigo.es

DOI: 10.1016/j.rser.2006.05.014

Publisher; 1987. p. 30-50


[18] Diaz LF, Savage GM, Golueke CG. Composting of municipal solid wastes. In: Tchobanoglous G, Kreith F, editors. Handbook of solid waste management. New York:

[19] Merrington G, Oliver I, Smernik RJ, McLaughlin MJ. The influence of sewage sludge properties on sludge-borne metal availability. Advances in Environmental Research.

[20] Smith KM, Fowler GD, Pullket S, Graham NJD. Sewage sludge-based adsorbents: A review of their production, properties and use in water treatment applications. Water

[21] Cieślik BM, Namieśnik J, Konieczka P. Review of sewage sludge management: Standards, regulations and analytical methods. Journal of Cleaner Production. 2015;**90**(Supplement C):

[22] Smith S. A critical review of the bioavailability and impacts of heavy metals in municipal solid waste composts compared to sewage sludge. Environmental International.

[23] Rule KL, Comber SDW, Ross D, Thornton A, Makropoulos CK, Rautiu R. Diffuse sources of heavy metals entering an urban wastewater catchment. Chemosphere. 2006;**63**(1):64-72.

[24] Sadef Y, Poulsen TG, Bester K. Modeling organic micro pollutant degradation kinetics during sewage sludge composting. Waste Management. 2014;**34**(11):2007-2013. DOI: 10.

[25] Poulsen TG, Bester K. Organic Micropollutant Degradation in Sewage Sludge during Composting under Thermophilic Conditions. Environmental Science & Technology.

[26] Cheng H-F, Kumar M, Lin J-G. Degradation kinetics of di-(2-ethylhexyl) phthalate (DEHP) and organic matter of sewage sludge during composting. Journal of Hazardous

[27] Rynk R. On-farm composting handbook. 1992; Available from: http://agris.fao.org/agris-

[28] Boletín Oficial del Estado. Real Decreto 506/2013, de 28 de junio, sobre productos fertilizantes (Royal Decree on fertilizers). núm. 164. Sect. 1 Jul 10, 2013 p. 51119-51207

[29] TMECC. In: Thompson WH, Leege PB, Millner PD, Watson ME, editors. Test Methods for the Examination of Composting and Compost. Bethesda, MD: Composting Council

[30] Bernal MP, Paredes C, Sánchez-Monedero MA, Cegarra J. Maturity and stability parameters of composts prepared with a wide range of organic wastes. Bioresource Technology.

Research and Education Foundation, and US Department of Agriculture; 2002

McGraw-Hill Inc.; 2002. p. 12.1-12.70

114 Sewage

1-15. DOI: 10.1016/j.jclepro.2014.11.031

DOI: 10.1016/j.chemosphere.2005.07.052

2010;**44**(13):5086-5091. DOI: 10.1021/es9038243

search/search.do?recordID=US19960026319

1998;**63**(1):91-99. DOI: 10.1016/S0960-8524(97)00084-9

Materials. 2008;**154**(1):55-62. DOI: 10.1016/j.jhazmat.2007.09.105

1016/j.wasman.2014.07.001

2003;**8**(1):21-36. DOI: 10.1016/S1093-0191(02)00139-9

2009;**35**(1):142-156. DOI: 10.1016/j.envint.2008.06.009

Research. 2009;**43**(10):2569-2594. DOI: 10.1016/j.watres.2009.02.038

## *Edited by Ivan X. Zhu*

Wastewater treatment and sludge disposal are important for protecting receiving rivers, lakes, and other water bodies, and vital for human health. Since excessive discharge may cause eutrophication and deterioration of aquatic systems, the US EPA and other national agencies have set guidelines for wastewater discharge standards. Conventional technologies are well developed and widely applied worldwide for wastewater treatment; however, new ideas and new technologies are gaining additional interest for the sake of water and energy reuse. While water is essential in arid regions, wastewater reuse and recycling have been playing an important role in human life. Although there are no universal standards for industrial and agriculture reuse, balancing wastewater treatment and public health protection presents challenges and opportunities.

Published in London, UK © 2018 IntechOpen © Kayla Gibson / unsplash

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