Environmental Emissions Monitoring and Mitigation

*Environmental Emissions*

2016;**11**(9):e0161851

Spectrum Disorder. PLoS One.

[98] Schraufnagel DE, Balmes JR, Cowl CT, et al. Air Pollution and Noncommunicable Diseases A Review by the Forum of International Respiratory Societies' Environmental Committee, Part 2: Air Pollution and Organ Systems. Chest. 2019;**155**(2):417-426

[99] Chan KH, Bennett DA, Kurmi OP, Yang L, Chen Y, Lv J, Guo Y, Bian Z, Yu C, Chen X, Dong C, Li L, Chen Z, Lam KBH; China Kadoorie Biobank Study Group. Solid fuels for cooking and tobacco use and risk of major chronic liver disease mortality: a prospective cohort study of 0.5 million Chinese adults. International Journal of Epidemiology 2020 ;49(1):45-55.

[100] Araviiskaia E, Berardesca E, Bieber T, et al. The impact of airborne pollution on skin. Journal of the

European Academy of Dermatology and Venereology. 2019;**33**(8):1496-1505

[101] Nguyen VH. Environmental Air Pollution and the Risk of Osteoporosis

Preventive Medicine and Public Health.

[102] Zhao CN, Xu Z, Wu GC, et al. Emerging role of air pollution in autoimmune diseases. Autoimmunity

Reviews. 2019;**18**(6):607-614

and Bone Fractures. Journal of

2018;**51**(4):215-216

**34**

**37**

**Chapter 3**

**Abstract**

Importance of Air Quality

to Air Pollution

performance of the network along time.

and performance

**1. Introduction**

and the environment.

*David Galán Madruga*

Networks in Controlling Exposure

An air quality monitoring network (AQMN) is a basic piece of environmental management due to that it satisfies the major role in monitoring of environment emissions, in special relevance to target air pollutants. An adequate installation would lead to support high efficiency of the network. Therefore, AQMN pre-layout should be considered as an essential factor in regarding with the location of fixed measurement stations within AQMN, as the minimum number of sampling points. Nevertheless, once AQMN has been already installed, and given that the spatial air pollutants pattern can vary along time, an assessment of the AQMN design would be addressed in order to identify the presence of potential redundant fixed monitoring stations. This approach would let to improve the AQMN performance, reduce maintenance costs of the network and consolidate the investment on those more efficient fixed stations. The chapter includes aspects relative to air pollutants measured by networks, their representativeness, limitations, importance, and the future needs. It ponders the need of re-assessment of the AQMN layout for assuring (i) a right evaluation of the human being exposure to atmospheric pollutants and controlling the environmental emissions into the atmosphere and (ii) an adequate

**Keywords:** environmental emissions, air quality, fixed monitoring stations, design

While technological advances have generated an improvement in the human being's life quality, they have also contributed to the emergence of associated issues, such as exponential industrial grown and increase of transportation networks, due to a fast growing population and its centralization into urban centers, mainly. As a consequence, the rise of the pollutant emissions toward the environmental compartments has been framed as a Public Health concern. Therefore, the impact of environmental emissions on the climate and the environment is an ultimate subject, both to local, regional as global level. Particularly, an increase of environmental well-being would bring in greater the quality of life, due to the exchange internal-external between the human being

#### **Chapter 3**

## Importance of Air Quality Networks in Controlling Exposure to Air Pollution

*David Galán Madruga*

#### **Abstract**

An air quality monitoring network (AQMN) is a basic piece of environmental management due to that it satisfies the major role in monitoring of environment emissions, in special relevance to target air pollutants. An adequate installation would lead to support high efficiency of the network. Therefore, AQMN pre-layout should be considered as an essential factor in regarding with the location of fixed measurement stations within AQMN, as the minimum number of sampling points. Nevertheless, once AQMN has been already installed, and given that the spatial air pollutants pattern can vary along time, an assessment of the AQMN design would be addressed in order to identify the presence of potential redundant fixed monitoring stations. This approach would let to improve the AQMN performance, reduce maintenance costs of the network and consolidate the investment on those more efficient fixed stations. The chapter includes aspects relative to air pollutants measured by networks, their representativeness, limitations, importance, and the future needs. It ponders the need of re-assessment of the AQMN layout for assuring (i) a right evaluation of the human being exposure to atmospheric pollutants and controlling the environmental emissions into the atmosphere and (ii) an adequate performance of the network along time.

**Keywords:** environmental emissions, air quality, fixed monitoring stations, design and performance

#### **1. Introduction**

While technological advances have generated an improvement in the human being's life quality, they have also contributed to the emergence of associated issues, such as exponential industrial grown and increase of transportation networks, due to a fast growing population and its centralization into urban centers, mainly. As a consequence, the rise of the pollutant emissions toward the environmental compartments has been framed as a Public Health concern. Therefore, the impact of environmental emissions on the climate and the environment is an ultimate subject, both to local, regional as global level. Particularly, an increase of environmental well-being would bring in greater the quality of life, due to the exchange internal-external between the human being and the environment.

Environmental emissions play a key role in the release of pollutants on air, water and soil matrix, which is relevant because drives a decline of biodiversity [1]. In this sense, deforestation, water pollution, acid rain or endangered animals are factors linked to likely environmental repercussions [2, 3]. In the health framework, numerous epidemiological studies associate the presence of pollutants in the environment and harmful effects on human being health [4, 5].

Taking into account the interaction between human being and environmental, the human well-being is a factor tied to the presence of clean air, otherwise, the emergence of harmful effects could drive to devastating implications on human health. According to the 68th World Health Assembly (see [6]), each year, a total of 4.3 and 3.7 million deaths result from exposure to indoor and outdoor pollutants, respectively.

Among different environmental compartments, this chapter will focus on atmospheric matrix, given that atmospheric pollution is considered the major environmental risk to human health worldwide. Atmospheric pollution result from the release of a damaging chemical or material into the atmosphere and it encompasses a wide variety of pollutants, either organic or inorganic compounds. Once air pollutants are released into the atmosphere, those ones can be exhibited both gaseous phase as solid and liquid particles suspended in the air (particulate material, PM) [7].

The occurrence of pollutants in the atmosphere depends on emissions sources. Although the atmospheric pollution is considered as a global character issue, the highest levels of air pollutants have been monitored in the developing countries, as a consequence of the industrial growth. A more detailed analysis would pointed to large cities [8, 9], where environmental emissions to atmospheric level could come from several types of sources of pollution, such as industrial developments implying combustion processes, vehicular emissions and domesticheating [10].

Environmental emissions have a direct effect on the outdoor ambient pollution, as well as on indoor air quality, given that outdoor emission sources are responsible for the presence of air pollutants at indoor environments [11], due to the gases and particles infiltration.

Based on previously mentioned, atmospheric pollution monitoring is of a fundamental importance in Public Health [12] in order to (i) control the human being exposure to air pollutants [13] and (ii) support the decision making on environmental management, in particular air quality management [14]. So, for example, an adequate management of major dominant emission sources in urban environments, as it can be to limit the road transport and more restricted industrial emissions, would result in lower levels of pollution into the atmosphere.

European Union develops Air Quality Directives [15] for setting air quality objectives in order to reduce potential harmful effects of air pollutants on human health and environment, establishing limit and target values for criteria of air pollutants. Air quality assessment is a responsibility of each Member States within their territory. These ones have the obligation for maintaining an air quality good, or improve it, and they should assume action in order to comply with the limit values and critical levels and, where possible, to reach the target values and longterm objectives. For that, Member States establish air quality monitoring networks (AQMN) in their territories for verifying compliance with those air quality objectives.

Therefore, AQMN performs an essential function within Public Health framework, monitoring environment emissions and controlling exposure in order to take care of human being health.

**39**

**Table 2.**

**Table 1.**

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution*

Criteria of air pollutants are those atmospheric pollutants generally monitored

The measurements recorded by AQMNs must be able to provide traceability, in order to compare air quality data among all Member States, for which those measures must be monitored using common measurement methods. For that, Member

The previously mentioned methods are cataloged as automatic method, nevertheless, the AQMNs dispose manual methods for determining the chemical composition of atmospheric particles (PM10 and PM2.5), mainly for heavy metals and polycyclic aromatic hydrocarbons. While the samples are collected by manual equipment installed at AQMN, their composition is analyzed in the laboratory.

Benzene (gas) 5 μg/m3 Limit value A calendar year Carbon monoxide (gas) 10 mg/m3 Limit value Maximum daily 8-hour mean

Limit value Limit value

Limit value Limit value

1, 2010)

Limit value Limit value

Target value (January 1, 2020) Limit value

EN 14211:2012 [19] Chemiluminescence

**Concept Averaging period**

**Measurement method**

chromatography

1 hour 1 day

1 hour A calendar year

Maximum daily 8-hour mean

1 day A calendar year

A calendar year A calendar year

by AQMNs. They usually measure the next legislated criteria of air pollutants (see **Table 1**): sulfur dioxide, nitrogen oxides (monoxide and dioxide nitrogen), benzene, carbon monoxide. Ozone and atmospheric particles (PM10 particles, with an aerodynamic diameter of 10 μm or less, and PM2.5, aerodynamic diameters

States apply normalized reference measurement methods (see **Table 2**).

**value**

125 μg/m3

40 μg/m3

Ozone (gas) 120 μg/m3 Target value (January

40 μg/m3

20 μg/m3

**standard**

Sulfur dioxide EN 14212:2012 [18] Ultraviolet fluorescence

Benzene EN 14662:2005 [20] Automated pumped sampling with in situ gas

Carbon monoxide EN 14626:2012 [21] Non-dispersive infrared spectroscopy Ozone EN 14625:2005 [22] Ultraviolet photometry PM10 and PM2.5 EN 12341:2015 [23] Gravimetric method

**2. Criteria of air pollutants measured at AQMN**

*DOI: http://dx.doi.org/10.5772/intechopen.92335*

**Pollutant Quantitative** 

Sulfur dioxide (gas) 350 μg/m3

Nitrogen dioxide (gas) 200 μg/m3

PM10 (particles) 50 μg/m3

PM2.5 (particles) 25 μg/m3

*Limit and target value for the protection of human health [15].*

*Reference measurement methods for measuring criteria of air pollutants.*

**Pollutant European** 

Monoxide and nitrogen

dioxide

≤2.5 μm) [16, 17].

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution DOI: http://dx.doi.org/10.5772/intechopen.92335*

#### **2. Criteria of air pollutants measured at AQMN**

Criteria of air pollutants are those atmospheric pollutants generally monitored by AQMNs. They usually measure the next legislated criteria of air pollutants (see **Table 1**): sulfur dioxide, nitrogen oxides (monoxide and dioxide nitrogen), benzene, carbon monoxide. Ozone and atmospheric particles (PM10 particles, with an aerodynamic diameter of 10 μm or less, and PM2.5, aerodynamic diameters ≤2.5 μm) [16, 17].

The measurements recorded by AQMNs must be able to provide traceability, in order to compare air quality data among all Member States, for which those measures must be monitored using common measurement methods. For that, Member States apply normalized reference measurement methods (see **Table 2**).

The previously mentioned methods are cataloged as automatic method, nevertheless, the AQMNs dispose manual methods for determining the chemical composition of atmospheric particles (PM10 and PM2.5), mainly for heavy metals and polycyclic aromatic hydrocarbons. While the samples are collected by manual equipment installed at AQMN, their composition is analyzed in the laboratory.


#### **Table 1.**

*Environmental Emissions*

respectively.

rial, PM) [7].

heating [10].

particles infiltration.

Environmental emissions play a key role in the release of pollutants on air, water and soil matrix, which is relevant because drives a decline of biodiversity [1]. In this sense, deforestation, water pollution, acid rain or endangered animals are factors linked to likely environmental repercussions [2, 3]. In the health framework, numerous epidemiological studies associate the presence of pollutants in the

Taking into account the interaction between human being and environmental, the human well-being is a factor tied to the presence of clean air, otherwise, the emergence of harmful effects could drive to devastating implications on human health. According to the 68th World Health Assembly (see [6]), each year, a total of 4.3 and 3.7 million deaths result from exposure to indoor and outdoor pollutants,

Among different environmental compartments, this chapter will focus on atmospheric matrix, given that atmospheric pollution is considered the major environmental risk to human health worldwide. Atmospheric pollution result from the release of a damaging chemical or material into the atmosphere and it encompasses a wide variety of pollutants, either organic or inorganic compounds. Once air pollutants are released into the atmosphere, those ones can be exhibited both gaseous phase as solid and liquid particles suspended in the air (particulate mate-

The occurrence of pollutants in the atmosphere depends on emissions sources.

Environmental emissions have a direct effect on the outdoor ambient pollution, as well as on indoor air quality, given that outdoor emission sources are responsible for the presence of air pollutants at indoor environments [11], due to the gases and

Based on previously mentioned, atmospheric pollution monitoring is of a fundamental importance in Public Health [12] in order to (i) control the human being exposure to air pollutants [13] and (ii) support the decision making on environmental management, in particular air quality management [14]. So, for example, an adequate management of major dominant emission sources in urban environments, as it can be to limit the road transport and more restricted industrial emissions,

European Union develops Air Quality Directives [15] for setting air quality objectives in order to reduce potential harmful effects of air pollutants on human health and environment, establishing limit and target values for criteria of air pollutants. Air quality assessment is a responsibility of each Member States within their territory. These ones have the obligation for maintaining an air quality good, or improve it, and they should assume action in order to comply with the limit values and critical levels and, where possible, to reach the target values and longterm objectives. For that, Member States establish air quality monitoring networks

(AQMN) in their territories for verifying compliance with those air quality

Therefore, AQMN performs an essential function within Public Health framework, monitoring environment emissions and controlling exposure in order to take

would result in lower levels of pollution into the atmosphere.

Although the atmospheric pollution is considered as a global character issue, the highest levels of air pollutants have been monitored in the developing countries, as a consequence of the industrial growth. A more detailed analysis would pointed to large cities [8, 9], where environmental emissions to atmospheric level could come from several types of sources of pollution, such as industrial developments implying combustion processes, vehicular emissions and domestic-

environment and harmful effects on human being health [4, 5].

**38**

objectives.

care of human being health.

*Limit and target value for the protection of human health [15].*


#### **Table 2.**

*Reference measurement methods for measuring criteria of air pollutants.*

The occurrence of criteria of air pollutants into the atmosphere measured at fixed stations within AQMN is dependent on several factors, such as meteorological features and sources of pollution.

#### **3. Types of air pollutant emission sources**

The comprehension of emission sources and knowledge on pollution levels reached in the air matrix could be useful tool for understanding the spatial and temporal distribution of air pollutants, which would provide an overview picture about human exposure to environmental emissions coming from different sources of contamination.

In function of their origin, it is necessary to distinct between anthropogenic and natural sources. Broadly, the first ones are sources that release mixtures of pollutants come from transport, power generation, industrial activity, biomass burning, and domestic heating, mainly in urban environments [24–26] while volcanic eruptions, plant emission and oceans are tied to natural sources. Nevertheless, in terms of released pollutant, the sources can be defined as primary and secondary. Primary emission sources result from the direct emissions from an air pollution source, while secondary emission sources result from the formation of a pollutant in the atmosphere from the chemical reaction between theirs precursors, which are emitted from air pollution primaries sources, and the meteorological variables. Finally, once pollutants are released, either from primary or secondary sources, the pollutants can be deposited on the Earth's terrestrial or aquatic surfaces, followed by re-emission to the atmosphere; in this case the sources are named as re-emission sources [27].

While the identification of emissions sources is a fundamental factor in order to carry out the distribution of the fixed monitoring stations within an AQMN, other elements also perform a primordial role, such as population density, peculiar features of target territory, amplitude of geographic area to be controlled as further meteorological variables.

#### **4. Air quality monitoring network**

#### **4.1 Concept**

AQMN is an essential element within environmental management, in special emphasis to air quality management. It is consisted of fixed monitoring stations for measuring air pollutants (see **Figure 1**). Although the total number of stations depends on several factors, according to Section 3, these ones should be attributed conveniently in the domain of interest for providing suitable air pollutant information and estimating the exposure of the ambient pollution on human being of righter way. So, one of the keys in the AQMN layout is the distribution of monitoring stations as well as the determination of a sufficient and confident number of sampling points for carrying out the air quality measurements. These features are associated with the network management, which should focus on reducing the fixed stations within the AQMN to a reliable and non-redundant number. So, the network would not duplicate information on air pollution.

Given that the assessment of air quality in Member States is approached by means of the data generated by AQMN, those ones divide their territories at zones and agglomerations in order to reach that objective. Generally, air quality must be assessed in all zones and agglomerations by means of one or more fixed stations.

**41**

**Figure 1.**

*Basic setup of a fixed monitoring station.*

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution*

The number of zones can vary in function of geographical location, distribution of emission sources and meteorology, although the final number of those ones must

Current European legislation [15] lays down criteria for siting fixed stations within an AQMN, pointing a wide number of considerations regards at macroscale siting of sampling points in order to protect the human health, vegetation and natural ecosystems. Similarly, in terms of microscale, the legislation set criteria relative to air flow no-restriction around the inlet of sampling point, its height regards to ground level (between 1.5 and 4 m) and distance regards to the edge of major junc-

Regarding to minimum number of fixed monitoring stations, the European legislation set criteria in those zones and agglomerations where fixed measurement is the sole source of information for evaluating compliance with limit values for the protection of human health and alert thresholds. This criterion is based on zone

Fixed stations included into AQMN can be sorted in function of several typolo-

• Urban stations: Those ones located at zones with presence of buildings of

• Suburban stations: Those ones located at zones with presence of buildings of continued way but separated by no-buildings areas, such as lakes, forests and

• Rural stations: Those ones located at zones not included within the previous

provide an adequate representation of the territory heterogeneity.

tions (at least 25 m) and the kerbside (no more than 10 m).

gies. So, in terms of area where is located it can be named:

inhabitant number and measured pollutants.

continued way.

agricultural land.

two categories.

*DOI: http://dx.doi.org/10.5772/intechopen.92335*

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution DOI: http://dx.doi.org/10.5772/intechopen.92335*

**Figure 1.** *Basic setup of a fixed monitoring station.*

*Environmental Emissions*

of contamination.

sources [27].

**4.1 Concept**

meteorological variables.

**4. Air quality monitoring network**

network would not duplicate information on air pollution.

features and sources of pollution.

**3. Types of air pollutant emission sources**

The occurrence of criteria of air pollutants into the atmosphere measured at fixed stations within AQMN is dependent on several factors, such as meteorological

The comprehension of emission sources and knowledge on pollution levels reached in the air matrix could be useful tool for understanding the spatial and temporal distribution of air pollutants, which would provide an overview picture about human exposure to environmental emissions coming from different sources

In function of their origin, it is necessary to distinct between anthropogenic and natural sources. Broadly, the first ones are sources that release mixtures of pollutants come from transport, power generation, industrial activity, biomass burning, and domestic heating, mainly in urban environments [24–26] while volcanic eruptions, plant emission and oceans are tied to natural sources. Nevertheless, in terms of released pollutant, the sources can be defined as primary and secondary. Primary emission sources result from the direct emissions from an air pollution source, while secondary emission sources result from the formation of a pollutant in the atmosphere from the chemical reaction between theirs precursors, which are emitted from air pollution primaries sources, and the meteorological variables. Finally, once pollutants are released, either from primary or secondary sources, the pollutants can be deposited on the Earth's terrestrial or aquatic surfaces, followed by re-emission to the atmosphere; in this case the sources are named as re-emission

While the identification of emissions sources is a fundamental factor in order to carry out the distribution of the fixed monitoring stations within an AQMN, other elements also perform a primordial role, such as population density, peculiar features of target territory, amplitude of geographic area to be controlled as further

AQMN is an essential element within environmental management, in special emphasis to air quality management. It is consisted of fixed monitoring stations for measuring air pollutants (see **Figure 1**). Although the total number of stations depends on several factors, according to Section 3, these ones should be attributed conveniently in the domain of interest for providing suitable air pollutant information and estimating the exposure of the ambient pollution on human being of righter way. So, one of the keys in the AQMN layout is the distribution of monitoring stations as well as the determination of a sufficient and confident number of sampling points for carrying out the air quality measurements. These features are associated with the network management, which should focus on reducing the fixed stations within the AQMN to a reliable and non-redundant number. So, the

Given that the assessment of air quality in Member States is approached by means of the data generated by AQMN, those ones divide their territories at zones and agglomerations in order to reach that objective. Generally, air quality must be assessed in all zones and agglomerations by means of one or more fixed stations.

**40**

The number of zones can vary in function of geographical location, distribution of emission sources and meteorology, although the final number of those ones must provide an adequate representation of the territory heterogeneity.

Current European legislation [15] lays down criteria for siting fixed stations within an AQMN, pointing a wide number of considerations regards at macroscale siting of sampling points in order to protect the human health, vegetation and natural ecosystems. Similarly, in terms of microscale, the legislation set criteria relative to air flow no-restriction around the inlet of sampling point, its height regards to ground level (between 1.5 and 4 m) and distance regards to the edge of major junctions (at least 25 m) and the kerbside (no more than 10 m).

Regarding to minimum number of fixed monitoring stations, the European legislation set criteria in those zones and agglomerations where fixed measurement is the sole source of information for evaluating compliance with limit values for the protection of human health and alert thresholds. This criterion is based on zone inhabitant number and measured pollutants.

Fixed stations included into AQMN can be sorted in function of several typologies. So, in terms of area where is located it can be named:


In terms of major dominant emission source:


#### **4.2 Representativeness of fixed monitoring stations within AQMN**

Regardless the function exhibited by fixed measurement stations included into an AQMN, as the assessment of air quality, cross-border pollution, spatial-temporal trends or exposure studies, the representativeness of each station should be considered as a primordial reflection. The efficiency degree of the fixed stations into AQMN can be assessed in terms of:

#### *4.2.1 Representation degree of any station within its zone or agglomeration*

Given that one target zone can be represented by one or more fixed stations, it is relevant to know the spatial representativeness of each station in order to evaluate whether air quality monitored by those ones can or not be extrapolated to all zone. In this sense, in order to provide an overview regards to atmospheric pollution within zone, the passive methodology simultaneously samples a large number of sampling points, which supplies opportune information on spatial pollution in the researched zone [28]. This approach lets to compare air quality data measured by AQMN vs. those ones monitored by passive methods, thereby confirming or not the station representativeness within target zone.

#### *4.2.2 Whole contribution of any station regarding environmental pollution data recorded by AQMN*

Spatial representativeness of the information provided by AQMN is dependent on type of station, in terms of spatial scale, and the pollutant.

Broadly, representativeness of a fixed station can be defined as the variability of the target pollutant concentrations around sampling point, while others authors enlarged the definition to the radius of a circular area where the concentration can vary up to ±20%, as maximum value [29].

The AQMN performance does not depend on number of fixed measurement stations, given that the presence of redundant stations could result in existence of non-efficient fixed stations. This means that potential emission sources close to those stations could have a strong probability of similitude. For this reason, the representativeness of each station within an AQMN should be properly studied.

Although a final agreement regarding on procedure for assessing the efficiency of fixed stations have not been reached, this subject have been widely studied in the scientific literature. Recent studies have reported on approaches in order to test the AQMN performance. They are based on the use of several combined chemometric techniques for reached the aforementioned objective. Some authors have used the analysis of correlation for revealing the existence of redundant fixed stations, although this method does not identify efficient stations. For that, they apply the principal component analysis technique, which appoints a

**43**

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution*

combined principal component analysis and multiple linear regression.

Spatial representativeness is required for distinct actions:

• Station classification and network design [31],

• Model validation and data assimilation [33].

AQMNs is not representative of the target zone.

*4.3.2 Relative to current European legislation*

optimize the AQMN performance.

new set of linearly uncorrelated stations [29]. Other studies have expanded the number of chemometric techniques, combining correlation analysis, principal component analysis, assignment method, clustering analysis and correspondence

A significate consideration would drive to know the contribution degree of each source of pollution in regarding with air pollutants levels reached into the atmosphere. Some authors have solved this subject using a combination of techniques,

Nevertheless, the practical application of the mentioned approaches were not tested along a period did not include in the development of these approaches. Similarly, they did not assess spatial information percentage that is lost when redesigning the AQMN due to the removal redundant fixed measurement stations. Therefore, while different approaches have been developed to estimate the area of spatial representativeness of monitoring stations, a unique robust methodology to assess the representativeness of in-situ measurements has not yet been agreed.

• Air quality and exposure assessment, for example, to estimate the air quality standards exceedance areas and to quantify the population exposure to the air

A lack of information in regarding with the AQMN performance, based on the representativeness of their fixed stations, would support their potential limitations.

Given that air quality in any zone, either local, regional or global, is dependent on a wide number of factors such emission sources (transport network and industries) and meteorological features, the assessment of atmospheric pollution is a hard assignment, and due to these factors it is specific for each zone. Therefore, it is possible that the spatial information on environmental pollution reported by

This limitation could influence on AQMN efficiency, if its function is framed within activity of informing population of levels which they are exposed to. This fact is relevant because numerous epidemiological studies use air quality data recorded by AQMNs, in order to associate air pollutant levels with damaging effects or hospital admissions. Nevertheless, the pollution data measured by AQMNs along study time is not equivalent to the daily concentrations which the human being is

While European Legislation clearly establish criteria, on the one hand, for siting potential fixed measurement stations and, on the other hand, setting minimum number of those ones, criteria for identifying the more representative fixed sampling points within AQMN is not considered. This fact is fundamental in order to

exposed to. So, the reached conclusions could exhibit a limited scope.

*DOI: http://dx.doi.org/10.5772/intechopen.92335*

analysis [30].

pollution [32],

*4.3.1 Relative to the design*

**4.3 Potential limitations of AQMN**

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution DOI: http://dx.doi.org/10.5772/intechopen.92335*

new set of linearly uncorrelated stations [29]. Other studies have expanded the number of chemometric techniques, combining correlation analysis, principal component analysis, assignment method, clustering analysis and correspondence analysis [30].

A significate consideration would drive to know the contribution degree of each source of pollution in regarding with air pollutants levels reached into the atmosphere. Some authors have solved this subject using a combination of techniques, combined principal component analysis and multiple linear regression.

Nevertheless, the practical application of the mentioned approaches were not tested along a period did not include in the development of these approaches. Similarly, they did not assess spatial information percentage that is lost when redesigning the AQMN due to the removal redundant fixed measurement stations.

Therefore, while different approaches have been developed to estimate the area of spatial representativeness of monitoring stations, a unique robust methodology to assess the representativeness of in-situ measurements has not yet been agreed.

Spatial representativeness is required for distinct actions:


A lack of information in regarding with the AQMN performance, based on the representativeness of their fixed stations, would support their potential limitations.

#### **4.3 Potential limitations of AQMN**

#### *4.3.1 Relative to the design*

*Environmental Emissions*

In terms of major dominant emission source:

to emission sources coming from vehicles.

attributed to any dominant emission source.

**4.2 Representativeness of fixed monitoring stations within AQMN**

*4.2.1 Representation degree of any station within its zone or agglomeration*

*4.2.2 Whole contribution of any station regarding environmental pollution data* 

on type of station, in terms of spatial scale, and the pollutant.

Spatial representativeness of the information provided by AQMN is dependent

Broadly, representativeness of a fixed station can be defined as the variability of the target pollutant concentrations around sampling point, while others authors enlarged the definition to the radius of a circular area where the concentration can

The AQMN performance does not depend on number of fixed measurement stations, given that the presence of redundant stations could result in existence of non-efficient fixed stations. This means that potential emission sources close to those stations could have a strong probability of similitude. For this reason, the representativeness of each station within an AQMN should be properly studied. Although a final agreement regarding on procedure for assessing the efficiency of fixed stations have not been reached, this subject have been widely studied in the scientific literature. Recent studies have reported on approaches in order to test the AQMN performance. They are based on the use of several combined chemometric techniques for reached the aforementioned objective. Some authors have used the analysis of correlation for revealing the existence of redundant fixed stations, although this method does not identify efficient stations. For that, they apply the principal component analysis technique, which appoints a

dent on industrial activities.

AQMN can be assessed in terms of:

station representativeness within target zone.

vary up to ±20%, as maximum value [29].

*recorded by AQMN*

• Traffic stations: Those ones which contamination levels are mainly appointed

• Industrial stations: Those ones which contamination levels are majorly depen-

• Background stations: Those ones which contamination levels cannot be directly

Regardless the function exhibited by fixed measurement stations included into an AQMN, as the assessment of air quality, cross-border pollution, spatial-temporal trends or exposure studies, the representativeness of each station should be considered as a primordial reflection. The efficiency degree of the fixed stations into

Given that one target zone can be represented by one or more fixed stations, it is relevant to know the spatial representativeness of each station in order to evaluate whether air quality monitored by those ones can or not be extrapolated to all zone. In this sense, in order to provide an overview regards to atmospheric pollution within zone, the passive methodology simultaneously samples a large number of sampling points, which supplies opportune information on spatial pollution in the researched zone [28]. This approach lets to compare air quality data measured by AQMN vs. those ones monitored by passive methods, thereby confirming or not the

**42**

Given that air quality in any zone, either local, regional or global, is dependent on a wide number of factors such emission sources (transport network and industries) and meteorological features, the assessment of atmospheric pollution is a hard assignment, and due to these factors it is specific for each zone. Therefore, it is possible that the spatial information on environmental pollution reported by AQMNs is not representative of the target zone.

This limitation could influence on AQMN efficiency, if its function is framed within activity of informing population of levels which they are exposed to. This fact is relevant because numerous epidemiological studies use air quality data recorded by AQMNs, in order to associate air pollutant levels with damaging effects or hospital admissions. Nevertheless, the pollution data measured by AQMNs along study time is not equivalent to the daily concentrations which the human being is exposed to. So, the reached conclusions could exhibit a limited scope.

#### *4.3.2 Relative to current European legislation*

While European Legislation clearly establish criteria, on the one hand, for siting potential fixed measurement stations and, on the other hand, setting minimum number of those ones, criteria for identifying the more representative fixed sampling points within AQMN is not considered. This fact is fundamental in order to optimize the AQMN performance.

#### *4.3.3 Relative to the development of specific procedure for evaluating the representativeness of fixed stations*

FARIMODE study [34] reported on collected information coming from questionnaire to get technical information concerning the methodologies used to estimate the representativeness of air quality monitoring stations. The questionnaire was answered by 22 workgroups from 14 different countries providing information on 25 methodologies.

Major methodological limitations were appointed to input data availability (9 answers), expert or local knowledge (1), modeling domain (1), modeling uncertainties (6), input data uncertainties (10), temporal-spatial resolution (7), directive metrics (1), computational resources (4), pollutants (2), definition of parameters of methodology (3), coverage of station network (1) and no limitation (2). Within this study, a relevant conclusion was the possibility for examining if the similarities or discrepancies between the representativeness estimates are more or less significant according to the concentration levels measured by target station.

#### **4.4 Importance of AQMNs**

Consequently to previously mentioned, an AQMN play a paramount lead in the evaluation of the air quality [35], in order to:


Besides, in the case of Member States, those ones must report to European Commission on recorded pollution data, which lets to evaluate the cross-border pollution and model the spatial-temporal air pollution pattern, among others applications.

AQMN links important subjects framed into Public Health, such as sources of pollution, environmental emissions, outdoor air pollutant levels and human health. Therefore, AQMN proves a helpful implement for estimating risk associated with human being exposure to air pollutant levels occurred into the atmosphere.

#### **4.5 Management of AQMNs**

Within the European Union, Member States are liable for controlling and assuring data quality of fixed monitoring stations. Each one establishes the necessary number and the location of fixed measurement stations included in their AQMNs, in order to ensure an adequate air quality assessment in its territory and comply with air quality standards. Similarly, each Member State is responsible for managing their AQMNs, according to requirements set in current European Legislation, meaning, the used measurement methods should be those ones included in air quality standards (they have been mentioned in **Table 2**). Similarly, they should guarantee a proper maintenance of those measure devices employed for monitoring

**45**

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution*

automated methods and the data is registered hourly or daily.

tive measurement devices from weekly or monthly exposure.

the criteria set in the air quality standards.

criteria, methodology, etc.

Pages/default.aspx, accessed March 6, 2020).

**4.6 Data measured by AQMNs**

capture (temporal coverage).

atmospheric pollutants in the outdoor ambient air. For that, the air quality standards [18–23] set several basic qualifications regards to the measure devices and

• Components of sampling system: (i) Sampling line: standards indicate the frequency of clear or, if necessary, its change, (ii) Particle filters: standards indicate where should site and (iii) Sampling pump: standards set the sampling

• Equipment requirements. They depend on target atmospheric pollutant. The components of the devices used for measuring atmospheric pollutants are described in the Air Quality Standards. The next devices can be differenced:

Continuous devices: The air pollutant levels are continuously measured using

Integrated devices: Levels of the target air pollutants are measured by manual or

Static devices: Levels of the target air pollutants are estimated by using qualita-

• Maintenance operations: The Air Quality Standards determine those necessary actions in order to test if an equipment is working within specifications marked by the manufacturer. For that aim, technical aspects such as verification of zero, the higher concentration level and lack of fit, among other should be checked. All these tests should provide satisfactory results, complying with

• Equipment calibration: Standards exhibit the frequency of calibration for each criteria of air pollutant, as well as recommended concentration/s, acceptation

• Quality control and quality assurance: The execution of this subject assures that the uncertainty or dispersion associated with the measured values by AQMNs fall down criteria set by current European Legislation. For that, the

More detailed information about this section can be found in air quality standards, which have been published by CEN/TC 624 Work Programme and can be acquired through European Committee for Standardization (https://www.cen.eu/

Given that the AQMNs management is a responsibility for the Member States, those ones should ensure valid air quality data. The data registered during maintenance, check and calibration processes should be not included within the air quality dataset, as well as the faulty data. The air quality standards establish requirements relative to the way for expressing the air quality data (number of decimals) and data

At the State level, Member States transfer air quality data to Europe Union. Those data can be compared given that, on the one hand, their measure was monitored using reference methods and, on the other hand, they complied with those QC/QA criteria set by air quality standards. As an example, the European

compliance of the previous requirements should be reached.

*DOI: http://dx.doi.org/10.5772/intechopen.92335*

flux required for working properly.

their management:

automatic analyzers.

#### *Importance of Air Quality Networks in Controlling Exposure to Air Pollution DOI: http://dx.doi.org/10.5772/intechopen.92335*

*Environmental Emissions*

on 25 methodologies.

**4.4 Importance of AQMNs**

exposed to [30],

applications.

**4.5 Management of AQMNs**

evaluation of the air quality [35], in order to:

• Identify predominant emission sources [36],

• Assist to authorities in decisions making.

*representativeness of fixed stations*

*4.3.3 Relative to the development of specific procedure for evaluating the* 

according to the concentration levels measured by target station.

FARIMODE study [34] reported on collected information coming from questionnaire to get technical information concerning the methodologies used to estimate the representativeness of air quality monitoring stations. The questionnaire was answered by 22 workgroups from 14 different countries providing information

Major methodological limitations were appointed to input data availability (9 answers), expert or local knowledge (1), modeling domain (1), modeling uncertainties (6), input data uncertainties (10), temporal-spatial resolution (7), directive metrics (1), computational resources (4), pollutants (2), definition of parameters of methodology (3), coverage of station network (1) and no limitation (2). Within this study, a relevant conclusion was the possibility for examining if the similarities or discrepancies between the representativeness estimates are more or less significant

Consequently to previously mentioned, an AQMN play a paramount lead in the

• Inform to the population in regarding with pollution levels which they are

Besides, in the case of Member States, those ones must report to European Commission on recorded pollution data, which lets to evaluate the cross-border pollution and model the spatial-temporal air pollution pattern, among others

AQMN links important subjects framed into Public Health, such as sources of pollution, environmental emissions, outdoor air pollutant levels and human health. Therefore, AQMN proves a helpful implement for estimating risk associated with human being exposure to air pollutant levels occurred into the atmosphere.

Within the European Union, Member States are liable for controlling and assuring data quality of fixed monitoring stations. Each one establishes the necessary number and the location of fixed measurement stations included in their AQMNs, in order to ensure an adequate air quality assessment in its territory and comply with air quality standards. Similarly, each Member State is responsible for managing their AQMNs, according to requirements set in current European Legislation, meaning, the used measurement methods should be those ones included in air quality standards (they have been mentioned in **Table 2**). Similarly, they should guarantee a proper maintenance of those measure devices employed for monitoring

• Know spatial-temporal pattern of air pollutants (see **Figure 1**),

• Support the development of monitoring strategies [37] and.

**44**

atmospheric pollutants in the outdoor ambient air. For that, the air quality standards [18–23] set several basic qualifications regards to the measure devices and their management:


Continuous devices: The air pollutant levels are continuously measured using automatic analyzers.

Integrated devices: Levels of the target air pollutants are measured by manual or automated methods and the data is registered hourly or daily.

Static devices: Levels of the target air pollutants are estimated by using qualitative measurement devices from weekly or monthly exposure.


More detailed information about this section can be found in air quality standards, which have been published by CEN/TC 624 Work Programme and can be acquired through European Committee for Standardization (https://www.cen.eu/ Pages/default.aspx, accessed March 6, 2020).

#### **4.6 Data measured by AQMNs**

Given that the AQMNs management is a responsibility for the Member States, those ones should ensure valid air quality data. The data registered during maintenance, check and calibration processes should be not included within the air quality dataset, as well as the faulty data. The air quality standards establish requirements relative to the way for expressing the air quality data (number of decimals) and data capture (temporal coverage).

At the State level, Member States transfer air quality data to Europe Union. Those data can be compared given that, on the one hand, their measure was monitored using reference methods and, on the other hand, they complied with those QC/QA criteria set by air quality standards. As an example, the European

Monitoring and Evaluation Programme (EMEP) is the co-operative program for assessing long range transmission of atmospheric pollutants over Europe. Member States have an air quality network in order to monitor background levels of air pollutants. Information relative to this subject can be found in https://www.emep. int/ (accessed March 6, 2020), where emission data, measurement data and modeling results for air pollutants are available through an open's database. Similarly, air quality data monitored by Member States is reported by European Environment Agency (https://www.eea.europa.eu/data-and-maps/explore-interactive-maps/upto-date-air-quality-data, accessed March 9, 2020) by means of interactive maps and reports. Other website providing real-time air pollution data by interactive maps in Europe and other countries over the world can be visited at https://aqicn.org/map/ europe/ (accessed March 9, 2020).

#### **4.7 Potential suggestions for improving the AQMN management**

Given that the AQMNs have a large historical series of ambient air data for target air pollutants [38] (sulfur dioxide, nitrogen monoxide and dioxide, benzene, carbon monoxide, ozone and atmospheric particles), a count of the number of times that the measurements exceeded the limit and target value established by the European Legislation would help to identify those air pollutants who should be monitored.

As a consequence, the measurement of those air pollutants which do not exceeded the limit values could be reduced in terms of number of fixed monitoring stations, which would give to reinvest those economic resources towards the monitor of other pollutants, e.g. benzene, given that the measurements of this last pollutant are very limited within AQMNs and, according to European Legislation, its measure is mandatory.

Based on the role of AQMNs within environmental emission control, and given that their spatial monitoring coverture is limited [39], nowadays, new wireless low cost sensors are available in order to assess pollution levels in ambient [40] and indoor air [41], by simultaneous monitoring in an elevated number of sampling points,

#### **5. Possible future trends**

At European level, although the application of measurement methods for monitoring air pollutants in AQMNs is normalized by Air Quality Standards, providing traceability to air pollution data among Member States, a harmonized technique for estimating the representativeness of fixed monitoring stations have not been defined.

In the future, the major requirement in regards to AQMN design should point towards the development of a particular methodology for evaluating representativeness of fixed monitoring sampling points within a network.

On the one hand, this methodology should offer evaluation criteria which would assure an adequate estimation of the representativeness and, on the other hand, they should be common and similar to all Member States.

The implementation of this reflection would result in a significant benefit for population, given that an optimization regards to location of fixed stations, and by extension on AQMN performance, it would aid to control the human exposure to atmospheric pollution in a more precise way, supporting a more realistic estimate of human health risk.

**47**

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution*

The binomial between environmental emissions and human exposure leads to Public Health concerns. In particular, emissions towards ambient air are considered the higher environmental risk. In order to control those issues, AQMNs play a paramount role for controlling air pollution in order to evaluate the compliance with those air quality objectives set by Air Quality European Standards and assist to authorities in decisions making. They consist of fixed monitoring stations and measure several criteria of air pollutants. Although each fixed station should be representative of an around area, the spatial coverture of AQMNs is very limited, due to the restricted number of sampling points as a consequence of the large investment need for setting up an AQMN. Current European legislation lays down criteria for supporting location and minimum number of the fixed measurement stations within AQMN. There are numerous websites exhibiting air quality data (at local, regional and global level), by means of reports, interactive maps or time-real data. In order to support the AQMN management, a study regards to number of times that air pollutant measures have exceeded the criteria of air quality set in European Legislation should be addressed, for identifying the pollutants which should be

A relevant subject of an AQMN would point to its layout. Although, the legislation does not set methods for evaluating representativeness of the fixed measurement points or requirements for refereeing representativeness degree, this one should be tested over the time, given that new emission air pollutant sources can be

Therefore, the deployment of a harmonized methodological framework is required, which allows to establish a comprehensive and comparative evaluation of the AQMN efficacy, by evaluating the representativeness of fixed monitoring

This methodology should be assisted by scientists, AQMN's managers and technicians and experts of air quality and it should lay down the concrete type of method to use, either passive methodology, modeling, series of historical data, a

The development of this harmonized methodological would help to the reporting of spatial representativeness by the Member States to Commission European by

The author declares no conflict of interest. This work does not have commercial

This work did not receive any specific grant from funding agencies in the public,

emerged, which would directly affect to the AQMN performance.

combination of them or other methods.

means of a common approach.

purposes, only scientific ones.

commercial, or not-for-profit sectors.

**Conflict of interest**

**Other declarations**

*DOI: http://dx.doi.org/10.5772/intechopen.92335*

**6. Conclusions**

measured.

stations.

### **6. Conclusions**

*Environmental Emissions*

europe/ (accessed March 9, 2020).

monitored.

pling points,

defined.

its measure is mandatory.

**5. Possible future trends**

Monitoring and Evaluation Programme (EMEP) is the co-operative program for assessing long range transmission of atmospheric pollutants over Europe. Member States have an air quality network in order to monitor background levels of air pollutants. Information relative to this subject can be found in https://www.emep. int/ (accessed March 6, 2020), where emission data, measurement data and modeling results for air pollutants are available through an open's database. Similarly, air quality data monitored by Member States is reported by European Environment Agency (https://www.eea.europa.eu/data-and-maps/explore-interactive-maps/upto-date-air-quality-data, accessed March 9, 2020) by means of interactive maps and reports. Other website providing real-time air pollution data by interactive maps in Europe and other countries over the world can be visited at https://aqicn.org/map/

**4.7 Potential suggestions for improving the AQMN management**

Given that the AQMNs have a large historical series of ambient air data for target air pollutants [38] (sulfur dioxide, nitrogen monoxide and dioxide, benzene, carbon monoxide, ozone and atmospheric particles), a count of the number of times that the measurements exceeded the limit and target value established by the European Legislation would help to identify those air pollutants who should be

As a consequence, the measurement of those air pollutants which do not exceeded the limit values could be reduced in terms of number of fixed monitoring stations, which would give to reinvest those economic resources towards the monitor of other pollutants, e.g. benzene, given that the measurements of this last pollutant are very limited within AQMNs and, according to European Legislation,

Based on the role of AQMNs within environmental emission control, and given that their spatial monitoring coverture is limited [39], nowadays, new wireless low cost sensors are available in order to assess pollution levels in ambient [40] and indoor air [41], by simultaneous monitoring in an elevated number of sam-

At European level, although the application of measurement methods for monitoring air pollutants in AQMNs is normalized by Air Quality Standards, providing traceability to air pollution data among Member States, a harmonized technique for estimating the representativeness of fixed monitoring stations have not been

In the future, the major requirement in regards to AQMN design should point towards the development of a particular methodology for evaluating representa-

On the one hand, this methodology should offer evaluation criteria which would

assure an adequate estimation of the representativeness and, on the other hand,

The implementation of this reflection would result in a significant benefit for population, given that an optimization regards to location of fixed stations, and by extension on AQMN performance, it would aid to control the human exposure to atmospheric pollution in a more precise way, supporting a more realistic estimate of

tiveness of fixed monitoring sampling points within a network.

they should be common and similar to all Member States.

**46**

human health risk.

The binomial between environmental emissions and human exposure leads to Public Health concerns. In particular, emissions towards ambient air are considered the higher environmental risk. In order to control those issues, AQMNs play a paramount role for controlling air pollution in order to evaluate the compliance with those air quality objectives set by Air Quality European Standards and assist to authorities in decisions making. They consist of fixed monitoring stations and measure several criteria of air pollutants. Although each fixed station should be representative of an around area, the spatial coverture of AQMNs is very limited, due to the restricted number of sampling points as a consequence of the large investment need for setting up an AQMN. Current European legislation lays down criteria for supporting location and minimum number of the fixed measurement stations within AQMN. There are numerous websites exhibiting air quality data (at local, regional and global level), by means of reports, interactive maps or time-real data.

In order to support the AQMN management, a study regards to number of times that air pollutant measures have exceeded the criteria of air quality set in European Legislation should be addressed, for identifying the pollutants which should be measured.

A relevant subject of an AQMN would point to its layout. Although, the legislation does not set methods for evaluating representativeness of the fixed measurement points or requirements for refereeing representativeness degree, this one should be tested over the time, given that new emission air pollutant sources can be emerged, which would directly affect to the AQMN performance.

Therefore, the deployment of a harmonized methodological framework is required, which allows to establish a comprehensive and comparative evaluation of the AQMN efficacy, by evaluating the representativeness of fixed monitoring stations.

This methodology should be assisted by scientists, AQMN's managers and technicians and experts of air quality and it should lay down the concrete type of method to use, either passive methodology, modeling, series of historical data, a combination of them or other methods.

The development of this harmonized methodological would help to the reporting of spatial representativeness by the Member States to Commission European by means of a common approach.

#### **Conflict of interest**

The author declares no conflict of interest. This work does not have commercial purposes, only scientific ones.

#### **Other declarations**

This work did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

*Environmental Emissions*

#### **Author details**

David Galán Madruga Atmospheric Pollution Area, National Center for Environment Health, Carlos III Health Institute, Madrid, Spain

\*Address all correspondence to: david.galan@isciii.es

© 2020 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.

**49**

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution*

particulate phases of pollutants in near-ground ambient air. Science of the Total Environment.

[8] Han C, Liu R, Luo H, Li G, Ma S, Chen J, et al. Pollution profiles of volatile organic compounds from different urban functional areas in Guangzhou China based on GC/ MS and PTR-TOF-MS: Atmospheric

environmental implications. Atmospheric Environment.

[9] Abbass RA, Kumar P,

El-Gendy A. Car users exposure to particulate matter and gaseous air pollutants in megacity Cairo. Sustainable Cities and Society.

[10] González CM, Gómez CD, Rojas NY, Acevedo H, Aristizábal BH.

vehicular and point-source industrial emissions of air pollutants in a medium-sized Andean city. Atmospheric Environment.

García-Cambero JP. Particle-associated polycyclic aromatic hydrocarbons in a representative urban location (indoor-outdoor) from South Europe: Assessment of potential sources and cancer risk to humans. Indoor Air.

[12] Omrani H, Omrani B, Parmentier B, Helbich M. Spatio-temporal data on the air pollutant nitrogen dioxide derived from Sentinel satellite for France. Data

[13] Xing Y, Brimblecombe P. Urban park layout and exposure to traffic-derived air pollutants. Landscape and Urban

Relative impact of on-road

[11] Madruga DG, Ubeda RM, Terroba JM, dos Santos SG,

2019;**683**:221-230

2019;**214**:116843

2020;**56**:102090

2017;**152**:279-289

2019;**29**(5):817-827

in Brief. 2020;**28**:105089

Planning. 2020;**194**:103682

*DOI: http://dx.doi.org/10.5772/intechopen.92335*

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[2] Chi Y, Yang P, Ren S, Ma N, Yang J, Xu Y. Effects of fertilizer types and water quality on carbon dioxide emissions from soil in wheat-maize rotations. Science of the Total Environment. 2020;**698**:134010

[3] Liu Z, Li D, Zhang J, Saleem M, Zhang Y, Ma R, et al. Effect of simulated acid rain on soil CO2, CH4 and N2O emissions and microbial communities in an agricultural soil. Geoderma.

[4] Kim E, Park H, Hong Y-C, Ha M, Kim Y, Kim B-N, et al. Prenatal exposure

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**48**

**Author details**

David Galán Madruga

Health Institute, Madrid, Spain

\*Address all correspondence to: david.galan@isciii.es

provided the original work is properly cited.

Atmospheric Pollution Area, National Center for Environment Health, Carlos III

© 2020 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,

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2010;**10**(8):3561-3581

2013;**77**:325-337

[30] Zhao L, Xie Y, Wang J, Xu X. A performance assessment and adjustment program for air quality monitoring networks in Shanghai. Atmospheric Environment. 2015;**122**:382-392

Buchmann B. Assessment of parameters describing representativeness of air quality in-situ measurement sites. Atmospheric Chemistry and Physics.

[32] Malherbe L, Jimmink B, de Leeuw F, Schneider P, Ung A. Analysis of station classification and network design in EU28 (& other EEA) countries. EEA &

Maiheu B, Janssen S, Dons E. Evaluation of the RIO-IFDM-street canyon model chain. Atmospheric Environment.

[34] Martín F, Santiago JL, Kracht O, García L, Gerboles M. FAIRMODE spatial representativeness feasibility study. Report EUR 27385 EN. 2015

[35] Rosario L, Francesco SP. Analysis

predominant pollutants in the Catania's air quality monitoring stations. Energy

and characterization of the

Procedia. 2016;**101**:337-344

ETC/ACM Working Paper. 2013

[33] Lefebvre W, Van Poppel M,

*Importance of Air Quality Networks in Controlling Exposure to Air Pollution DOI: http://dx.doi.org/10.5772/intechopen.92335*

local emission sources for ammonia in an urban environment. Bulletin of Environmental Contamination and Toxicology. 2018;**100**(4):593-599

*Environmental Emissions*

2020;**43**:101376

2020;**246**:125767

2013;**14**(13):1262-1263

[14] McDonald F, Horwell CJ, Wecker R, Dominelli L, Loh M, Kamanyire R, et al. Facemask use for community protection from air pollution disasters: An ethical overview and framework to guide agency decision making. International Journal of Disaster Risk Reduction.

monoxide by non-dispersive infrared

[22] EN 14625:2012. Ambient air quality. Standard method for the measurement of the concentration of ozone by ultraviolet photometry. 2012

[23] EN 12341:2014. Ambient air. Standard gravimetric measurement method for the determination of the PM10 or PM2.5 mass concentrations of suspended particulate matter. 2014

[24] Song J, Zhao C, Lin T, Li X, Prishchepov AV. Spatio-temporal patterns of traffic-related air pollutant emissions in different urban functional zones estimated by real-time video and deep learning technique. Journal of Cleaner Production. 2019;**238**:117881

[25] Zhou Y, Luo B, Li J, Hao Y, Yang W, Shi F, et al. Characteristics of six criteria air pollutants before, during, and after a severe air pollution episode caused by biomass burning in the southern Sichuan Basin China. Atmospheric Environment. 2019;**215**:116840

Dong L, Duan H. Unveiling the driving mechanism of air pollutant emissions from thermal power generation in China: A provincial-level spatiotemporal analysis. Resources, Conservation and

[26] Wang Y, Song J, Yang W,

Recycling. 2019;**151**:104447

Outdoor-Air-Pollution-2015

[28] Galán Madruga D, Fernández Patier R, Sintes Puertas MA, Romero García MD, Cristóbal LA. Characterization and

[27] Outdoor Air Pollution. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Vol. 109. International Agency for Research on Cancer; 2016. Available from: https://publications.iarc. fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/

spectroscopy. 2012

[15] Directive 2008/50/EC of the

ELEX:32008L0050&from=EN

[16] Yang J, Kang S, Ji Z, Yin X,

[17] Loomis D, Grosse Y, Lauby-Secretan B, Ghissassi FE,

[18] EN 14212:2012. Ambient air. Standard method for the measurement of the concentration of sulphur dioxide

by ultraviolet fluorescence. 2012

[19] EN 14211:2012. Ambient air. Standard method for the measurement of the concentration of nitrogen dioxide and nitrogen monoxide by

[21] EN 14626:2012. Ambient air. Standard method for the measurement

of the concentration of carbon

[20] EN 14662:2005. Ambient air quality. Standard method for measurement of benzene concentrations. pumped sampling followed by thermal desorption and gas chromatography.

chemiluminescence. 2012

Bouvard V, Benbrahim-Tallaa L, et al. The carcinogenicity of outdoor air pollution. The Lancet Oncology.

Tripathee L. Investigating air pollutant concentrations, impact factors, and emission control strategies in western China by using a regional climatechemistry model. Chemosphere.

European Parliament and of the Council on 21 May 2008 on ambient air quality and cleaner air for Europe. 2008. Available from: https://eur-lex.europa. eu/legal-content/EN/TXT/PDF/?uri=C

**50**

2005

[29] Chow JC, Chen L-WA, Watson JG, Lowenthal DH, Magliano KA, Turkiewicz K, et al. PM2.5 chemical composition and spatiotemporal variability during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS): CRPAQS PM2.5 spatiotemporal variability. Journal of Geophysical Research-Atmospheres. 2006;**111**(D10):1-17

[30] Zhao L, Xie Y, Wang J, Xu X. A performance assessment and adjustment program for air quality monitoring networks in Shanghai. Atmospheric Environment. 2015;**122**:382-392

[31] Henne S, Brunner D, Folini D, Solberg S, Klausen J, Buchmann B. Assessment of parameters describing representativeness of air quality in-situ measurement sites. Atmospheric Chemistry and Physics. 2010;**10**(8):3561-3581

[32] Malherbe L, Jimmink B, de Leeuw F, Schneider P, Ung A. Analysis of station classification and network design in EU28 (& other EEA) countries. EEA & ETC/ACM Working Paper. 2013

[33] Lefebvre W, Van Poppel M, Maiheu B, Janssen S, Dons E. Evaluation of the RIO-IFDM-street canyon model chain. Atmospheric Environment. 2013;**77**:325-337

[34] Martín F, Santiago JL, Kracht O, García L, Gerboles M. FAIRMODE spatial representativeness feasibility study. Report EUR 27385 EN. 2015

[35] Rosario L, Francesco SP. Analysis and characterization of the predominant pollutants in the Catania's air quality monitoring stations. Energy Procedia. 2016;**101**:337-344

[36] Pires JCM, Sousa SIV, Pereira MC, Alvim-Ferraz MCM, Martins FG. Management of air quality monitoring using principal component and cluster analysis—Part I: SO2 and PM10. Atmospheric Environment. 2008;**42**(6):1249-1260

[37] Kao J-J, Hsieh M-R. Utilizing multiobjective analysis to determine an air quality monitoring network in an industrial district. Atmospheric Environment. 2006;**40**(6):1092-1103

[38] Barrero MA, Orza JAG, Cabello M, Cantón L. Categorisation of air quality monitoring stations by evaluation of PM10 variability. Science of the Total Environment. 2015;**524**(525):225-236

[39] Munir S, Mayfield M, Coca D, Jubb SA. Structuring an integrated air quality monitoring network in large urban areas—Discussing the purpose, criteria and deployment strategy. Atmospheric Environment X. 2019;**2**:100027

[40] Molka-Danielsen J, Engelseth P, Wang H. Large scale integration of wireless sensor network technologies for air quality monitoring at a logistics shipping base. Journal of Industrial Information Integration. 2018;**10**:20-28

[41] Salman N, Kemp AH, Khan A, Noakes CJ. Real time wireless sensor network (WSN) based indoor air quality monitoring system. IFAC-Paper. 2019;**52**(24):324-327

**53**

**Chapter 4**

**Abstract**

cultivations.

**1. Introduction**

Mitigation

*and Muhammad Nadeem Zafar*

Industrial Air Emission Pollution:

Potential Sources and Sustainable

Air of cities especially in the developing parts of the world is turning into a serious environmental interest. The air pollution is because of a complex interaction of dispersion and emission of toxic pollutants from manufactories. Air pollution caused due to the introduction of dust particles, gases, and smoke into the atmosphere exceeds the air quality levels. Air pollutants are the precursor of photochemical smog and acid rain that causes the asthmatic problems leading into serious illness of lung cancer, depletes the stratospheric ozone, and contributes in global warming. In the present industrial economy era, air pollution is an unavoidable product that cannot be completely removed but stern actions can reduce it. Pollution can be reduced through collective as well as individual contributions. There are multiple sources of air pollution, which are industries, fossil fuels, agro waste, and vehicular emissions. Industrial processes upgradation, energy efficiency, agricultural waste burning control, and fuel conversion are important aspects to reducing pollutants which create the industrial air pollution. Mitigations are necessary to reduce the threat of air pollution using the various applicable technologies like CO2 sequestering, industrial energy efficiency, improving the combustion processes of the vehicular engines, and reducing the gas production from agriculture

**Keywords:** environmental, pollution, industrial, emission, global warming

A unique chemical wrapping that promotes life on glob and support numerous activities often referred to as air. Rapid industrialization is becoming serious concern for fresh air and healthy life [1–3]. Abundant discharge of industrial toxin making natural environment harmful, unstable, and uncomfortable for physical and also for biological environment and it leads to pollution by energy sources and chemical substances. Physical and biological environment are damage by the heat and pollutants in the air. These pollutants including vapors, aerosols, solid particles, toxic gases and smoke drive from industrial processes. Emission of air pollutants is also because of many human actions. List of six air pollutants presented by World health organization (WHO) which known as classic air pollutants in industrialized countries as nitrogen oxides (NOx), sulfur dioxide (SO2), carbon monoxide (CO),

*Rabia Munsif, Muhammad Zubair, Ayesha Aziz* 

#### **Chapter 4**

## Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation

*Rabia Munsif, Muhammad Zubair, Ayesha Aziz and Muhammad Nadeem Zafar*

#### **Abstract**

Air of cities especially in the developing parts of the world is turning into a serious environmental interest. The air pollution is because of a complex interaction of dispersion and emission of toxic pollutants from manufactories. Air pollution caused due to the introduction of dust particles, gases, and smoke into the atmosphere exceeds the air quality levels. Air pollutants are the precursor of photochemical smog and acid rain that causes the asthmatic problems leading into serious illness of lung cancer, depletes the stratospheric ozone, and contributes in global warming. In the present industrial economy era, air pollution is an unavoidable product that cannot be completely removed but stern actions can reduce it. Pollution can be reduced through collective as well as individual contributions. There are multiple sources of air pollution, which are industries, fossil fuels, agro waste, and vehicular emissions. Industrial processes upgradation, energy efficiency, agricultural waste burning control, and fuel conversion are important aspects to reducing pollutants which create the industrial air pollution. Mitigations are necessary to reduce the threat of air pollution using the various applicable technologies like CO2 sequestering, industrial energy efficiency, improving the combustion processes of the vehicular engines, and reducing the gas production from agriculture cultivations.

**Keywords:** environmental, pollution, industrial, emission, global warming

#### **1. Introduction**

A unique chemical wrapping that promotes life on glob and support numerous activities often referred to as air. Rapid industrialization is becoming serious concern for fresh air and healthy life [1–3]. Abundant discharge of industrial toxin making natural environment harmful, unstable, and uncomfortable for physical and also for biological environment and it leads to pollution by energy sources and chemical substances. Physical and biological environment are damage by the heat and pollutants in the air. These pollutants including vapors, aerosols, solid particles, toxic gases and smoke drive from industrial processes. Emission of air pollutants is also because of many human actions. List of six air pollutants presented by World health organization (WHO) which known as classic air pollutants in industrialized countries as nitrogen oxides (NOx), sulfur dioxide (SO2), carbon monoxide (CO),

and suspended particulate matter [4]. A number of industrial sources are responsible for the emission of carbon monoxide along with, fuel-fired boilers, internal combustion gas boilers and gas stoves [5]. The quality of the combustion process is primary indicated by carbon dioxide. Emissions of CO2, as a result of combustion of fuels, are creating consequences on environment [6]. For the industrial combustion system carbon dioxide was also examined a major greenhouse gas [7]. For the emission of carbon dioxide from any type of combustion source a prescribed national standard was present but it is important to check that carbon dioxide emission enter into air at steep rate. Oxides of nitrogen as nitrogen dioxide (NO2) and nitric oxide (NO) produce from thermal power plants, vehicles, industrial process and, coal burning processes [8]. Oxides of nitrogen are produced by the reaction of free oxygen and nitrogen of air which achieved at high temperature during combustion process. Fuels, rich in sulfur contents produce sulfur dioxide (SO2) gas when used for the energy. Bennett [9] reported sulfur dioxide lifetime is about 10 days in air. Industrial stacks emitting sulfur dioxide because fuels contain a standards higher concentration of sulfur. Generally, in Pakistan the electric power supply is not adequate and consistent for supporting employments; consequently, to overcome electric energy shortage all business sectors still extensively use their private generator (**Figure 1**).

These generators mostly installed next to their services or along the road which is not an appropriate location. Therefore, by importing exhaust gases into the air they create many complications to the people who are traveling on the roads and the resident. Smoke opacity of industrial gas is also a parameter which has considerable potential to enhance environmental air pollution by smoke particles emission. Industrial stack points were also analyzed with reference to clean air for smoke opacity (%). It was noticed that boilers operating on furnace oil have larger value of smoke than on natural gas. According to an estimate, at least 3000 different chemicals have been identified in air through sampling of various nature. A term commonly used to describe any harmful chemical or other substance that pollutes

#### **Figure 1.**

*Presentation of energy sources based upon hydrocarbon fuels: (A) domestic generator; (B) power houses; (C) industrial generators; and (D) energy production.*

**55**

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation*

the air we breathe, thereby reducing its life-sustaining quality is called air pollutant. In principle, air pollutants refer to any chemical substance that exceeds the concentration or characteristics identified as safe for the natural ingredients in the air both by nature or anthropogenically. More strictly, pollutants can be defined a substance which is potentially unsafe to the well-being or health of humans, plant and animal life, or ecosystems. Air pollution is characterized as "the presence of substances in the atmosphere that may adversely affect humans and the environment." It may be a single chemical that is initially produced, or chemicals that are formed by subsequent reactions. According to the World Health Organization (WHO), poor outdoor air caused 4.2 million premature deaths in 2016, of which about 90% were in third world countries. Indoor smoke poses a health threat to 3.0 billion people through heating system and burning biomass, kerosene and coal [10, 11]. Air pollution is linked to a high incidence of respiratory diseases such as cancer, heart disease, stroke and asthma [12]. According to estimates from the American Lung Association, nearly 134 million people are at risk due to air pollution [13]. Although these effects come from long-term exposure, air pollution can also cause acute problems such as sneezing and coughing, eye discomfort, headache, and dizziness [14]. Particles smaller than 10 microns (classified as PM10 or PM2.5 even smaller) pose higher health risks because they can be breathed deeply into the lungs and can enter the bloodstream where air pollutants and nanoparticles have the direct impact

Pollutants are commonly classified into solid, liquid, or gaseous substances that are discharged into the air from a fixed or mobile source, then transmit through air, and contribute in chemo physical transformation, and eventually return to the ground. It is impossible to describe the full range of potential sources and actual damage caused by various sources of air pollution but few which are more vulner-

Fossil fuels as coal and oil for electricity production and road transportation, add huge amount of air pollutants like carbon dioxide, nitrogen and sulfur dioxide. Sulfur dioxide, oxides of nitrogen and fly ash are produced as main pollutants if coal is used as a fuel. Major pollutants during combustion of oil are oxides of nitrogen and sulfur dioxide, whereas coal emits particulate air pollution to the atmosphere. Similarly, important air pollutants emitted from power station are particulate matter (fly ash and soot) oxides of nitrogen (NO2 and NO) and sulfur oxides (SO3 and SO2) [16, 17]. These pollutants and other closely related chemicals are primarily source for acid rain. When PM is released into the atmosphere due to traffic and industries, these PM scatter the visible part of the sunlight radiation, but the other part of the spectrum particularly inferred and far-infrared, cause the internal heating effect of the air atmosphere below the PM surface. The Sun radiation is heating our air from outside and the traffic and industries from inside. And the PM surface is like a shield or barrier, through the heat diffusion cannot

Volcanic eruption disperses an enormous amount of sulfur dioxide into the atmosphere along with ash and smoke particle sometimes causes the temperature to rise up over the years. Particles in the air, based on their chemical composition, can also have a direct impact of being separated from climate change. They either

*DOI: http://dx.doi.org/10.5772/intechopen.93104*

on our health [15].

**2. Sources of air pollution**

able are discussed below:

**2.1 Combustion of fossil fuels**

penetrate bidirectional ways.

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation DOI: http://dx.doi.org/10.5772/intechopen.93104*

the air we breathe, thereby reducing its life-sustaining quality is called air pollutant. In principle, air pollutants refer to any chemical substance that exceeds the concentration or characteristics identified as safe for the natural ingredients in the air both by nature or anthropogenically. More strictly, pollutants can be defined a substance which is potentially unsafe to the well-being or health of humans, plant and animal life, or ecosystems. Air pollution is characterized as "the presence of substances in the atmosphere that may adversely affect humans and the environment." It may be a single chemical that is initially produced, or chemicals that are formed by subsequent reactions. According to the World Health Organization (WHO), poor outdoor air caused 4.2 million premature deaths in 2016, of which about 90% were in third world countries. Indoor smoke poses a health threat to 3.0 billion people through heating system and burning biomass, kerosene and coal [10, 11]. Air pollution is linked to a high incidence of respiratory diseases such as cancer, heart disease, stroke and asthma [12]. According to estimates from the American Lung Association, nearly 134 million people are at risk due to air pollution [13]. Although these effects come from long-term exposure, air pollution can also cause acute problems such as sneezing and coughing, eye discomfort, headache, and dizziness [14]. Particles smaller than 10 microns (classified as PM10 or PM2.5 even smaller) pose higher health risks because they can be breathed deeply into the lungs and can enter the bloodstream where air pollutants and nanoparticles have the direct impact on our health [15].

#### **2. Sources of air pollution**

*Environmental Emissions*

and suspended particulate matter [4]. A number of industrial sources are responsible for the emission of carbon monoxide along with, fuel-fired boilers, internal combustion gas boilers and gas stoves [5]. The quality of the combustion process is primary indicated by carbon dioxide. Emissions of CO2, as a result of combustion of fuels, are creating consequences on environment [6]. For the industrial combustion system carbon dioxide was also examined a major greenhouse gas [7]. For the emission of carbon dioxide from any type of combustion source a prescribed national standard was present but it is important to check that carbon dioxide emission enter into air at steep rate. Oxides of nitrogen as nitrogen dioxide (NO2) and nitric oxide (NO) produce from thermal power plants, vehicles, industrial process and, coal burning processes [8]. Oxides of nitrogen are produced by the reaction of free oxygen and nitrogen of air which achieved at high temperature during combustion process. Fuels, rich in sulfur contents produce sulfur dioxide (SO2) gas when used for the energy. Bennett [9] reported sulfur dioxide lifetime is about 10 days in air. Industrial stacks emitting sulfur dioxide because fuels contain a standards higher concentration of sulfur. Generally, in Pakistan the electric power supply is not adequate and consistent for supporting employments; consequently, to overcome electric energy shortage all business sectors still extensively use their private generator (**Figure 1**). These generators mostly installed next to their services or along the road which is not an appropriate location. Therefore, by importing exhaust gases into the air they create many complications to the people who are traveling on the roads and the resident. Smoke opacity of industrial gas is also a parameter which has considerable potential to enhance environmental air pollution by smoke particles emission. Industrial stack points were also analyzed with reference to clean air for smoke opacity (%). It was noticed that boilers operating on furnace oil have larger value of smoke than on natural gas. According to an estimate, at least 3000 different chemicals have been identified in air through sampling of various nature. A term commonly used to describe any harmful chemical or other substance that pollutes

*Presentation of energy sources based upon hydrocarbon fuels: (A) domestic generator; (B) power houses;* 

**54**

**Figure 1.**

*(C) industrial generators; and (D) energy production.*

Pollutants are commonly classified into solid, liquid, or gaseous substances that are discharged into the air from a fixed or mobile source, then transmit through air, and contribute in chemo physical transformation, and eventually return to the ground. It is impossible to describe the full range of potential sources and actual damage caused by various sources of air pollution but few which are more vulnerable are discussed below:

#### **2.1 Combustion of fossil fuels**

Fossil fuels as coal and oil for electricity production and road transportation, add huge amount of air pollutants like carbon dioxide, nitrogen and sulfur dioxide. Sulfur dioxide, oxides of nitrogen and fly ash are produced as main pollutants if coal is used as a fuel. Major pollutants during combustion of oil are oxides of nitrogen and sulfur dioxide, whereas coal emits particulate air pollution to the atmosphere. Similarly, important air pollutants emitted from power station are particulate matter (fly ash and soot) oxides of nitrogen (NO2 and NO) and sulfur oxides (SO3 and SO2) [16, 17]. These pollutants and other closely related chemicals are primarily source for acid rain. When PM is released into the atmosphere due to traffic and industries, these PM scatter the visible part of the sunlight radiation, but the other part of the spectrum particularly inferred and far-infrared, cause the internal heating effect of the air atmosphere below the PM surface. The Sun radiation is heating our air from outside and the traffic and industries from inside. And the PM surface is like a shield or barrier, through the heat diffusion cannot penetrate bidirectional ways.

Volcanic eruption disperses an enormous amount of sulfur dioxide into the atmosphere along with ash and smoke particle sometimes causes the temperature to rise up over the years. Particles in the air, based on their chemical composition, can also have a direct impact of being separated from climate change. They either

change the composition or size and may deplete the nutrients biosphere, damage crops, and forests and destroy cultural monuments such as monuments and statues. Many living and non-living sources emit carbon dioxide that contribute largely as pollutant. Carbon dioxide is the most common greenhouse gas, among many others which traps heat into the atmosphere via infrared radiation matching vibrations and causes climate change through global warming. Over the past 150 years, humans have driven enough CO2 into the atmosphere to make its levels higher than they have been for hundreds of thousands of years. Air pollution in many cases prevents photosynthesis, which has a significant impact on the plants evolution, which has serious consequences for purifying the air we breathe. It also results to form acid rain, atmospheric precipitation in the form of rain, snow or fog, frost, which is released at the time of fossil fuels burning and converted by contact with water vapor in the atmosphere.

#### **2.2 Industrial emissions**

Industrial process emits huge amounts of organic compounds carbon monoxide, hydrocarbons, and chemicals into the air. A high quantity of carbon dioxide is the reasons for the greenhouse effect in the air. As the greenhouse gases absorbs infrared radiation from the surface of the planet so its presence is good for the planet. The recent climate change is due to excessive quantity of these gases as well as PM into the atmosphere [18, 19]. Different greenhouse gases contribute differently in global warming due to their unique physical and chemical properties, molecular weight and the lifetime in the atmosphere. A simple working method can calculate the relative contribution of the unit emissions of each gas relative to the cumulative CO2 unit emissions over a fixed period of time [20, 21]. Therefore, global warming potential (GWP) can be defined as the warming effect of any greenhouse gas relative to CO2 over a certain period of time. Greenhouse gas emissions from various sources have led to climate change, which has been accompanied by an increase in greenhouse gases [22, 23]. Greenhouse gas emissions change the Climate that is a global issue having significantly negative impacts on economic growth humans, and natural resources [24–26]. The main greenhouse gases (GHGs) and their relative quantities are carbon dioxide, (9–26%), water vapor, H2O (36–70%), nitrous oxide (3–7%), methane, (4–9%), and other trace gases [27]. Among all the greenhouse gases, CO2 and CH4 cause major global surface temperature increase [28]. These gases are emitted by natural and anthropogenically. After carbon dioxide, methane is the second gas that contributes to global warming. Methane has larger impacts as a greenhouse gas than carbon dioxide, with global warming potential (GWP)s 21–25 times higher than CO2 [29–32].

#### **2.3 Agricultural sources**

Agriculture activities often release harmful chemicals like pesticides and fertilizers [33]. Organic matter gradually reduces the water and oxygen in soil during flooding of rice fields; as a result, methane is produce by anaerobic decomposition [34, 35]. Globally methane emission is much lower than CO2 emissions annually. The concentration of CH4 in the air is 200 times lesser than carbon dioxide [36] but approximately 20% effects of global warming, because of methane [37, 38]. Naturally it is emitted by marshland [39], termites, wildfires [36], grasslands [36], coal seams [40] and lakes [41]. Human sources of methane include public solid waste landfills coal mine paddy fields oil and gas drilling, pastures rising main sewers, wastewater treatment plants, manure management and agricultural

**57**

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation*

products. Its emission through agriculture sector increased by 11–24% from 2000

Natural sources are particulate matter (PM) includes dust produced from the earth's crustal surface, coastal sea salt, form pollens of plant and animal debris [51]. Volcanic eruptions also contribute huge quantities of particles into the environment. Majorly an amount of 3.0 thousand tons of sulfur dioxide emits every day while episodes of great activity. Forest fires of rural areas produce large amounts of all kind of particulate matter including carbon black. Among other sources of natural pollution of air includes lighting in the sky that generate significant quantities of oxides of nitrogen (NOx); hydrogen sulphide produced from oceans algae and marshy methane. Additionally, concentrations of ozone at ground level, formed because of reaction of nitrogen gases and volatile organic compounds in the presence of sunlight. As far as the human sources are concerned in urban areas, air pollutants come from human-activities, such as cars, trucks, air planes, marine engines, etc. and factories, electric power plants, etc. Nowadays, vehicles on the road constitute the major source of air pollution in the populated areas of countries. Carbon constituted fossil fuels produces carbon monoxide and hydrocarbons whereas NOx a combination of nitrogen and oxygen gases produced at high temperature. Another very significant thing that road transport accounts a major source of air pollution [52]. It is specified that road transport is the second source of air

emissions up to 28.6% after the industrial use of solvents which is 41.4%.

Countries, departments and researchers all over the world are dealing for several

forms of mitigations for air pollution. In order to restrict global warming, there is a need to take different measures. Important is the addition of more renewable energy sources, substituting gasoline vehicles with zero-emission vehicles as electric vehicles. As an example rapid industrial expansion is China. In china the government is supporting coal-fired power plant. Similarly, in the United States, emission standards setting has improved the air quality, especially in places of worth importance. Contrarily by adding ventilation, using air purifiers, purifying radon gas, running exhaust fans in bathrooms and kitchens and avoiding smoking people can avoid indoor air pollution. While working on a home project, use paint and other products with less volatile compounds. Countries all over the globe have commitments to limit carbon dioxide emissions and other greenhouse gases in the light of Paris Agreement [53, 54] banning hydrophobic hydrocarbons (HFCs) other than

In this method carbon dioxide is extracted from the air using a solid or liquid adsorbent. Examples of mostly used solid adsorbents include, activated carbon, zeolite, or activated alumina whereas liquid sorbents include, high pH solutions of sodium hydroxide, potassium hydroxide some organic solvents such as monoethanolamine [56, 57]. A method for capturing carbon dioxide from the air includes a number of steps including exposing CO2 in air to a solution containing an alkali to

obtain an alkaline solution that absorbs the carbon dioxide [56].

*DOI: http://dx.doi.org/10.5772/intechopen.93104*

**2.4 Other natural and anthropogenic sources**

to 2010 [33, 42–50].

**3. Mitigation**

chlorofluorocarbon CFCs [55].

**3.1 CO2 sequestering**

products. Its emission through agriculture sector increased by 11–24% from 2000 to 2010 [33, 42–50].

#### **2.4 Other natural and anthropogenic sources**

Natural sources are particulate matter (PM) includes dust produced from the earth's crustal surface, coastal sea salt, form pollens of plant and animal debris [51]. Volcanic eruptions also contribute huge quantities of particles into the environment. Majorly an amount of 3.0 thousand tons of sulfur dioxide emits every day while episodes of great activity. Forest fires of rural areas produce large amounts of all kind of particulate matter including carbon black. Among other sources of natural pollution of air includes lighting in the sky that generate significant quantities of oxides of nitrogen (NOx); hydrogen sulphide produced from oceans algae and marshy methane. Additionally, concentrations of ozone at ground level, formed because of reaction of nitrogen gases and volatile organic compounds in the presence of sunlight. As far as the human sources are concerned in urban areas, air pollutants come from human-activities, such as cars, trucks, air planes, marine engines, etc. and factories, electric power plants, etc. Nowadays, vehicles on the road constitute the major source of air pollution in the populated areas of countries. Carbon constituted fossil fuels produces carbon monoxide and hydrocarbons whereas NOx a combination of nitrogen and oxygen gases produced at high temperature. Another very significant thing that road transport accounts a major source of air pollution [52]. It is specified that road transport is the second source of air emissions up to 28.6% after the industrial use of solvents which is 41.4%.

#### **3. Mitigation**

*Environmental Emissions*

vapor in the atmosphere.

**2.2 Industrial emissions**

21–25 times higher than CO2 [29–32].

**2.3 Agricultural sources**

change the composition or size and may deplete the nutrients biosphere, damage crops, and forests and destroy cultural monuments such as monuments and statues. Many living and non-living sources emit carbon dioxide that contribute largely as pollutant. Carbon dioxide is the most common greenhouse gas, among many others which traps heat into the atmosphere via infrared radiation matching vibrations and causes climate change through global warming. Over the past 150 years, humans have driven enough CO2 into the atmosphere to make its levels higher than they have been for hundreds of thousands of years. Air pollution in many cases prevents photosynthesis, which has a significant impact on the plants evolution, which has serious consequences for purifying the air we breathe. It also results to form acid rain, atmospheric precipitation in the form of rain, snow or fog, frost, which is released at the time of fossil fuels burning and converted by contact with water

Industrial process emits huge amounts of organic compounds carbon monoxide, hydrocarbons, and chemicals into the air. A high quantity of carbon dioxide is the reasons for the greenhouse effect in the air. As the greenhouse gases absorbs infrared radiation from the surface of the planet so its presence is good for the planet. The recent climate change is due to excessive quantity of these gases as well as PM into the atmosphere [18, 19]. Different greenhouse gases contribute differently in global warming due to their unique physical and chemical properties, molecular weight and the lifetime in the atmosphere. A simple working method can calculate the relative contribution of the unit emissions of each gas relative to the cumulative CO2 unit emissions over a fixed period of time [20, 21]. Therefore, global warming potential (GWP) can be defined as the warming effect of any greenhouse gas relative to CO2 over a certain period of time. Greenhouse gas emissions from various sources have led to climate change, which has been accompanied by an increase in greenhouse gases [22, 23]. Greenhouse gas emissions change the Climate that is a global issue having significantly negative impacts on economic growth humans, and natural resources [24–26]. The main greenhouse gases (GHGs) and their relative quantities are carbon dioxide, (9–26%), water vapor, H2O (36–70%), nitrous oxide (3–7%), methane, (4–9%), and other trace gases [27]. Among all the greenhouse gases, CO2 and CH4 cause major global surface temperature increase [28]. These gases are emitted by natural and anthropogenically. After carbon dioxide, methane is the second gas that contributes to global warming. Methane has larger impacts as a greenhouse gas than carbon dioxide, with global warming potential (GWP)s

Agriculture activities often release harmful chemicals like pesticides and fertilizers [33]. Organic matter gradually reduces the water and oxygen in soil during flooding of rice fields; as a result, methane is produce by anaerobic decomposition [34, 35]. Globally methane emission is much lower than CO2 emissions annually. The concentration of CH4 in the air is 200 times lesser than carbon dioxide [36] but approximately 20% effects of global warming, because of methane [37, 38]. Naturally it is emitted by marshland [39], termites, wildfires [36], grasslands [36], coal seams [40] and lakes [41]. Human sources of methane include public solid waste landfills coal mine paddy fields oil and gas drilling, pastures rising main sewers, wastewater treatment plants, manure management and agricultural

**56**

Countries, departments and researchers all over the world are dealing for several forms of mitigations for air pollution. In order to restrict global warming, there is a need to take different measures. Important is the addition of more renewable energy sources, substituting gasoline vehicles with zero-emission vehicles as electric vehicles. As an example rapid industrial expansion is China. In china the government is supporting coal-fired power plant. Similarly, in the United States, emission standards setting has improved the air quality, especially in places of worth importance. Contrarily by adding ventilation, using air purifiers, purifying radon gas, running exhaust fans in bathrooms and kitchens and avoiding smoking people can avoid indoor air pollution. While working on a home project, use paint and other products with less volatile compounds. Countries all over the globe have commitments to limit carbon dioxide emissions and other greenhouse gases in the light of Paris Agreement [53, 54] banning hydrophobic hydrocarbons (HFCs) other than chlorofluorocarbon CFCs [55].

#### **3.1 CO2 sequestering**

In this method carbon dioxide is extracted from the air using a solid or liquid adsorbent. Examples of mostly used solid adsorbents include, activated carbon, zeolite, or activated alumina whereas liquid sorbents include, high pH solutions of sodium hydroxide, potassium hydroxide some organic solvents such as monoethanolamine [56, 57]. A method for capturing carbon dioxide from the air includes a number of steps including exposing CO2 in air to a solution containing an alkali to obtain an alkaline solution that absorbs the carbon dioxide [56].

#### **3.2 Biomass burning**

Incomplete combustion of biomass results into production of hazardous gases. The main sources of such emissions are burning of wood, domestic waste, agricultural residues, waste, and charcoal. In developing economies combustion of biomass generally refers to the biofuels combustion for heating, lighting purposes and cooking in small combustion equipment. Because the conditions of burning and types of these fuels vary widely, measures for this category are highly difficult and uncertain to predict.

#### **3.3 Coal mining**

Produced of methane by coalification process, and vegetation is transformed into coal by many environmental conditions [58]. The amount of methane gas evolved by mining operations is a function of two main factors: coal depth and coal level [59]. From coal mining, there are four main sources of methane emissions, which are underground coal mines and surface coal mines. These processes account for most of the global emissions of methane from mining. Surface coal mines emit much lower methane as compare to underground coal mines because generally coal mines are at lower rank and capture methane into methane during post-mining operations. Activities of coal mining and processing, continues after operations which emit the methane [60].

#### **3.4 Rice cultivation**

Methane emissions through rice production and cultivation can be decreased by selecting proper rice varieties, fertilizers, and water systems. It has been proved that larger total weight rice varieties emit less methane [61, 62]. Fresh straw in the 3 months before transplantation and combined with straw fertilizers before transplantation, plus methane emissions, intermittent irrigation were reduced by 23 and 49%, respectively [63]. Application of potassium fertilizer during flowering period drainage reduce methane emissions.

#### **3.5 Direct utilization of gas**

For the production of liquid natural gas and to run leachate evaporators landfill gas can be directly used as fuel. In industrial processes such as kiln operations, boilers, drying operations, and asphalt and cement production landfill methane gas can be used and transported. Natural gas collected from landfills can be transported to local industries directly and use as an alternative or supplementary fuel [64].

#### **3.6 Fuel conversion**

Shifting to low-carbon fuels from high-carbon can be comparatively cost-effective principle to reduce the emissions of gaseous because this enhance the efficiency of combustion and reduce the amount of pollutants. In addition, briquette coal and carbon burnout techniques are used in fuel based power plants to minimize the production of pollutants. This pre-combustion method requires almost no hardware changes to the facility and therefore has a lower investment cost. Fuel conversion application to industrial sectors such as the steel, cement and chemical CO2 emissions can be reduced by 10–20%. There are some essential interrogations about

**59**

manufacturing [68].

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation*

the opportunities that exist for converting fuels in a cost-effective manner. Fuel choices are usually industry dependent, so cost-effective alternatives are limited however, some special opportunities to replace coal-fired boilers with natural gas fired gas-driven steam production; and use natural gas instead of coal to burn blast furnaces [65]. For example, briquette alternative fuels result in a 9–16% increase in fuel costs, although an estimated 26% CO2 emissions are reduced. Improved fuel efficiency and reduced standard pollutant emissions depends on variable fuel costs which cannot be completely estimated. According to an estimate carbon depletion can save 1.5% of fuel costs. Carbon reductions achieved from ash, by replacing the production of Portland cement is estimated to reduce 144,000 tons of carbon

Improvement in the current combustion systems have the potential to gear up the energy efficiency. The average thermal performance of current combustion is 32–33% [67]. Control of wasted heat into electricity may result into efficiencies of 45–55%. According to the Department of Energy, the combined energy projects are the main source of greenhouse gases reduction. Technologies like the natural gas combined cycle and combined cycle gas turbine proved for the improving of combustion efficiency and proportionally reduced greenhouse gas emissions and standard pollutant emissions. Additionally, integrated gasification combined cycle system is a step forward to reduce the costs associated with capturing and separating CO2 from the exhaust stream. Increased operating and fuel costs may be offset by the combined benefits of increased efficiency, reduced pollutants, and credits for emission reductions. An ample evidence that industrial upgradation can reduce greenhouse gas emission, pollutants, and lower operating costs, and current environmental regulations have hindered the adoption of this technology [68]. Air quality regulations determine the operational fuel input rather than power output emission to upgrade of thermal efficiency. However, the environmental agencies provide a guidance document on energy efficiency which begun to address regulatory barriers to improving thermal efficiency [69]. Another source of energy efficiency that can be achieved in the industrial sector is the use of direct fossil fuels. Manufacturing is a major candidate for improving energy efficiency, both of which are achieved through many technological upgrades. Overall, process control and energy management systems for all industries can better control combustion efficiency and fuel use; combined heat and power systems can use waste heat as additional energy; high-efficiency, low-friction motors and drive systems improved the overall efficiency of successfully generating power. In addition to these general categories, various manufacturing industries also have opportunities to improve energy efficiency. Specific industrial sectors with greenhouse gas mitigation potential include cement manufacturing, metal production, refineries, pulp and paper mills, and chemical

Combustion efficiency of combustion systems depends on the factors such as type of combustion system, fuel, burner and air fuel ratio for combustion. Significant amount of air pollutants depending on nature of fuel enter into the environment. World health organization (WHO) has provided six listed air pollutants known as classic air pollutants [4]. If coal is used as a fuel, fly ash, sulfur dioxide and oxides of nitrogen are the major pollutant. Combustion of coal produces particulate air pollution whereas in case of oil, sulfur dioxide and oxides of nitrogen are major pollutants emitted to the atmosphere. Similarly, three major air

*DOI: http://dx.doi.org/10.5772/intechopen.93104*

dioxide annually [66].

**3.7 Combustion efficiency**

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation DOI: http://dx.doi.org/10.5772/intechopen.93104*

the opportunities that exist for converting fuels in a cost-effective manner. Fuel choices are usually industry dependent, so cost-effective alternatives are limited however, some special opportunities to replace coal-fired boilers with natural gas fired gas-driven steam production; and use natural gas instead of coal to burn blast furnaces [65]. For example, briquette alternative fuels result in a 9–16% increase in fuel costs, although an estimated 26% CO2 emissions are reduced. Improved fuel efficiency and reduced standard pollutant emissions depends on variable fuel costs which cannot be completely estimated. According to an estimate carbon depletion can save 1.5% of fuel costs. Carbon reductions achieved from ash, by replacing the production of Portland cement is estimated to reduce 144,000 tons of carbon dioxide annually [66].

#### **3.7 Combustion efficiency**

*Environmental Emissions*

**3.2 Biomass burning**

**3.3 Coal mining**

difficult and uncertain to predict.

which emit the methane [60].

drainage reduce methane emissions.

**3.5 Direct utilization of gas**

**3.4 Rice cultivation**

Incomplete combustion of biomass results into production of hazardous gases. The main sources of such emissions are burning of wood, domestic waste, agricultural residues, waste, and charcoal. In developing economies combustion of biomass generally refers to the biofuels combustion for heating, lighting purposes and cooking in small combustion equipment. Because the conditions of burning and types of these fuels vary widely, measures for this category are highly

Produced of methane by coalification process, and vegetation is transformed into coal by many environmental conditions [58]. The amount of methane gas evolved by mining operations is a function of two main factors: coal depth and coal level [59]. From coal mining, there are four main sources of methane emissions, which are underground coal mines and surface coal mines. These processes account for most of the global emissions of methane from mining. Surface coal mines emit much lower methane as compare to underground coal mines because generally coal mines are at lower rank and capture methane into methane during post-mining operations. Activities of coal mining and processing, continues after operations

Methane emissions through rice production and cultivation can be decreased by selecting proper rice varieties, fertilizers, and water systems. It has been proved that larger total weight rice varieties emit less methane [61, 62]. Fresh straw in the 3 months before transplantation and combined with straw fertilizers before transplantation, plus methane emissions, intermittent irrigation were reduced by 23 and 49%, respectively [63]. Application of potassium fertilizer during flowering period

For the production of liquid natural gas and to run leachate evaporators landfill

Shifting to low-carbon fuels from high-carbon can be comparatively cost-effective principle to reduce the emissions of gaseous because this enhance the efficiency of combustion and reduce the amount of pollutants. In addition, briquette coal and carbon burnout techniques are used in fuel based power plants to minimize the production of pollutants. This pre-combustion method requires almost no hardware changes to the facility and therefore has a lower investment cost. Fuel conversion application to industrial sectors such as the steel, cement and chemical CO2 emissions can be reduced by 10–20%. There are some essential interrogations about

gas can be directly used as fuel. In industrial processes such as kiln operations, boilers, drying operations, and asphalt and cement production landfill methane gas can be used and transported. Natural gas collected from landfills can be transported to local industries directly and use as an alternative or supplementary

**58**

fuel [64].

**3.6 Fuel conversion**

Improvement in the current combustion systems have the potential to gear up the energy efficiency. The average thermal performance of current combustion is 32–33% [67]. Control of wasted heat into electricity may result into efficiencies of 45–55%. According to the Department of Energy, the combined energy projects are the main source of greenhouse gases reduction. Technologies like the natural gas combined cycle and combined cycle gas turbine proved for the improving of combustion efficiency and proportionally reduced greenhouse gas emissions and standard pollutant emissions. Additionally, integrated gasification combined cycle system is a step forward to reduce the costs associated with capturing and separating CO2 from the exhaust stream. Increased operating and fuel costs may be offset by the combined benefits of increased efficiency, reduced pollutants, and credits for emission reductions. An ample evidence that industrial upgradation can reduce greenhouse gas emission, pollutants, and lower operating costs, and current environmental regulations have hindered the adoption of this technology [68]. Air quality regulations determine the operational fuel input rather than power output emission to upgrade of thermal efficiency. However, the environmental agencies provide a guidance document on energy efficiency which begun to address regulatory barriers to improving thermal efficiency [69]. Another source of energy efficiency that can be achieved in the industrial sector is the use of direct fossil fuels. Manufacturing is a major candidate for improving energy efficiency, both of which are achieved through many technological upgrades. Overall, process control and energy management systems for all industries can better control combustion efficiency and fuel use; combined heat and power systems can use waste heat as additional energy; high-efficiency, low-friction motors and drive systems improved the overall efficiency of successfully generating power. In addition to these general categories, various manufacturing industries also have opportunities to improve energy efficiency. Specific industrial sectors with greenhouse gas mitigation potential include cement manufacturing, metal production, refineries, pulp and paper mills, and chemical manufacturing [68].

Combustion efficiency of combustion systems depends on the factors such as type of combustion system, fuel, burner and air fuel ratio for combustion. Significant amount of air pollutants depending on nature of fuel enter into the environment. World health organization (WHO) has provided six listed air pollutants known as classic air pollutants [4]. If coal is used as a fuel, fly ash, sulfur dioxide and oxides of nitrogen are the major pollutant. Combustion of coal produces particulate air pollution whereas in case of oil, sulfur dioxide and oxides of nitrogen are major pollutants emitted to the atmosphere. Similarly, three major air pollutants, particulate matter (fly ash and soot) sulfur oxides (SO2 and SO3) and oxides of nitrogen (NO and NO2) emitted from power station.

Method for calculating efficiency:

$$\text{Efficiency (\% E)} = \text{100} - \Sigma \text{ losses} \tag{1}$$

Losses are as:


In one of our research work different textile units were examined for stack emissions from boilers and generators. **Table 1** illustrates the results of emissions from boilers. Values of carbon monoxide (CO) were in the range of 0 mg/Nm3 in CT-Tex to 4903 mg/Nm3 in HS-Tex. Most of the industries were in compliance of national quality standards of Pakistan, i.e., 800 mg/Nm3 . HS-Tex was exceeding the limit of standards for CO emission. Similarly, **Table 2** represents the gaseous emission of diesel generators. A massive amount of gaseous emissions are produced from generators along with heating which affect the climatic condition at the large scale [4].


**Table 1.**

*Gaseous emissions of boilers of textile industries operating with different fuels [70].*


**61**

**Author details**

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation*

Quality of life (air) in cities is getting worse as the industrialization, population, energy use and traffic increase. Some air pollutants in larger amount crossing WHO standards, mainly in cities of industrialized countries permitting meaningful statistical trends to air pollutants. The complexity of air pollutants, particularly related to the health impacts in cities, has improved indicators to analyze the accessible monitoring data sufficient for decision making and reporting. Our assessment illustrates that the economic costs of the environmental clash proceeding from sources of combustion in industries tested is potentially excessive. Regarding to the living quality it will be serious concern if no additional control measures were implemented in future. For industrial air pollution there is an immediate need to improve the evaluation and monitoring systems. In cities where strategic planning is not-existing or weak, to improve the quality of air there should be an implemen-

Authors are highly thankful to the IntechOpen publishing organization for open invitation to publish a chapter regarding the serious concern of the human atmosphere. Moreover, our especial thanks to Sara Debeuc, who sincerely coordinated to accomplish this chapter. Authors are obliged to Department of Chemistry, University of Gujrat, Pakistan, for providing support of facilities for completing

Rabia Munsif, Muhammad Zubair\*, Ayesha Aziz and Muhammad Nadeem Zafar

© 2020 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,

Department of Chemistry, University of Gujrat, Gujrat, Pakistan

\*Address all correspondence to: muhammad.zubair@uog.rdu.pk

provided the original work is properly cited.

*DOI: http://dx.doi.org/10.5772/intechopen.93104*

tation of environmental management system.

The authors declare no conflict of interest.

**Acknowledgements**

this manuscript.

**Conflict of interest**

**4. Conclusion**

#### **Table 2.**

*Gaseous emissions diesel generators operation in different industries [70].*

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation DOI: http://dx.doi.org/10.5772/intechopen.93104*

#### **4. Conclusion**

*Environmental Emissions*

Losses are as:

1.Temperature flue gas.

3.Combustion of hydrogen.

4.Un-measured losses.

CT-Tex to 4903 mg/Nm3

scale [4].

2.Moisture in fuel.

pollutants, particulate matter (fly ash and soot) sulfur oxides (SO2 and SO3) and

In one of our research work different textile units were examined for stack emissions from boilers and generators. **Table 1** illustrates the results of emissions from boilers. Values of carbon monoxide (CO) were in the range of 0 mg/Nm3

the limit of standards for CO emission. Similarly, **Table 2** represents the gaseous emission of diesel generators. A massive amount of gaseous emissions are produced from generators along with heating which affect the climatic condition at the large

**Industries Fuel CO CO2 NO + NO2 SO2 H2**

IP-Tex Furnace oil 12 221,964 437 3363 0.09 CT-Tex Natural gas 0 125,321 227 0 0.18 BR-Tex Natural gas 20 139,857 213 0 1.34 KH-Tex Natural gas 35 207,428 256 0 1.07 NF-Tex Natural gas 20 207,625 187 0 1.52 HS-Tex Natural gas 4903 58,732 121 0 174.2

**Industries CO CO2 NO + NO2 SO2 H2**

IP-Tex 975 21,714 542 80 3 CT-Tex 655 90,000 1342 175 2 BR-Tex 874 131,429 2297 211 2 KH-Tex 572 94,286 2445 265 0.7 NF-Tex 981 86,000 2144 145 3 HS-Tex 1927 76,143 315 65 4

**mg/Nm3 mg/Nm3 mg/Nm3 mg/Nm3 mg/Nm3**

Efficiency (% *E*) = 100 − Σ losses (1)

in HS-Tex. Most of the industries were in compliance of

**mg/Nm3 mg/Nm3 NOx g/Nm3 mg/Nm3 mg/Nm3**

in

. HS-Tex was exceeding

oxides of nitrogen (NO and NO2) emitted from power station.

national quality standards of Pakistan, i.e., 800 mg/Nm3

*Gaseous emissions diesel generators operation in different industries [70].*

*Gaseous emissions of boilers of textile industries operating with different fuels [70].*

Method for calculating efficiency:

**60**

**Table 2.**

**Table 1.**

Quality of life (air) in cities is getting worse as the industrialization, population, energy use and traffic increase. Some air pollutants in larger amount crossing WHO standards, mainly in cities of industrialized countries permitting meaningful statistical trends to air pollutants. The complexity of air pollutants, particularly related to the health impacts in cities, has improved indicators to analyze the accessible monitoring data sufficient for decision making and reporting. Our assessment illustrates that the economic costs of the environmental clash proceeding from sources of combustion in industries tested is potentially excessive. Regarding to the living quality it will be serious concern if no additional control measures were implemented in future. For industrial air pollution there is an immediate need to improve the evaluation and monitoring systems. In cities where strategic planning is not-existing or weak, to improve the quality of air there should be an implementation of environmental management system.

#### **Acknowledgements**

Authors are highly thankful to the IntechOpen publishing organization for open invitation to publish a chapter regarding the serious concern of the human atmosphere. Moreover, our especial thanks to Sara Debeuc, who sincerely coordinated to accomplish this chapter. Authors are obliged to Department of Chemistry, University of Gujrat, Pakistan, for providing support of facilities for completing this manuscript.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Author details**

Rabia Munsif, Muhammad Zubair\*, Ayesha Aziz and Muhammad Nadeem Zafar Department of Chemistry, University of Gujrat, Gujrat, Pakistan

\*Address all correspondence to: muhammad.zubair@uog.rdu.pk

© 2020 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.

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[28] Hansen J et al. Climate change and trace gases. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2007;**365**(1856):1925-1954

[29] Xiaoli C et al. Characteristics of environmental factors and their effects on CH4 and CO2 emissions from a closed landfill: An ecological case study of Shanghai. Waste Management. 2010;**30**(3):446-451

[30] Change I.P.O.C. 2006 IPCC Guidelines for National Greenhouse Gas Inventories. 2006

[31] Todd RW et al. Daily, monthly, seasonal, and annual ammonia emissions from southern high plains cattle feedyards. Journal of Environmental Quality. 2011;**40**(4):1090-1095

[32] Talyan V et al. Quantification of methane emission from municipal solid waste disposal in Delhi. Resources, Conservation and Recycling. 2007;**50**(3):240-259

[33] Dong H et al. Greenhouse gas emissions from swine manure stored at different stack heights. Animal Feed Science and Technology. 2011;**166**:557-561

[34] Huang Y, He Q. Study on the status of output and utilization of landfill gas in China. Journal of Sichuan

**62**

*Environmental Emissions*

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(EEMJ). 2015;**14**:1583-1593

[3] Kwun SK, Shin YK, Eom K.

[4] Tabaku A et al. Effects of air pollution on children's pulmonary health. Atmospheric Environment.

[5] Weng Z, Mudd GM, Martin T, Boyle CA. Pollutant loads from coal mining in Australia: Discerning trends from the National Pollutant Inventory (NPI). Environmental Science & Policy.

[6] Chungsangunsit T, Gheewala SH, Patumsawad S. Emission assessment of rice husk combustion for power production. World Academy of Science, Engineering and Technology.

[7] Aaheim A, Amundsen H, Dokken T, Wei T. Impacts and adaptation to climate

change in European economies. Global Environmental Change.

[8] Vaz AIF, Ferreira EC. Air

Modelling. 2009;**33**:1957-1969

pollution control with semi-infinite programming. Applied Mathematical

2003;**38**:2549-2563

2011;**45**(40):7540-7545

2012;**19**:78-89

2009;**53**:1070

2012;**22**:959-968

Estimation of methane emission from rice cultivation in Korea. Journal of Environmental Science and Health. Part A, Toxic/Hazardous Substances & Environmental Engineering.

[1] Fanizza C, Baiguera S, Incoronato F, Ferrari C, Inglessis M, Ferdinandi M, et al. Aromatic hydrocarbon levels and PM 2.5 characterization in rome urban area: Preliminary results. Environmental Engineering & Management Journal

[9] Bennett G. 1994. Occupational exposures to mists and vapours from strong organic acids and other industrial chemicals. International Agency for Research on Cancer (IARC). Vol. 54. Geneva, Switzerland: World Health Organization; 1992. p. 336. ISBN: 92-832-1254-1. SWF 65, US \$58.50.

[10] Karthik S, Sriram A, Vinoth B. Automatic health management system in Urbanized hospitals. Research and Applications: Embedded System.

[11] Organization, W.H. World Health Statistics 2016: Monitoring Health for the SDGs Sustainable Development Goals. World Health

[12] To T et al. Progression from asthma to chronic obstructive pulmonary disease. Is air pollution a risk factor? American Journal of Respiratory and Critical Care Medicine.

[13] Park YM, Kwan M-P. Individual exposure estimates may be erroneous when spatiotemporal variability of air pollution and human mobility are ignored. Health & Place. 2017;**43**:85-94

[14] Lawrence A, Khan T, Azad I. Indoor air quality assessment and its impact on health in context to the household conditions in Lucknow. Global NEST

[15] Idarraga MA et al. Relationships between short-term exposure to an indoor environment and dry eye (DE) symptoms. Journal of Clinical Medicine.

[16] Kim IS, Lee JY, Kim YP. Impact of polycyclic aromatic hydrocarbon (PAH) emissions from North Korea to the air quality in the Seoul Metropolitan

Elsevier

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[36] Mackie K, Cooper C. Landfill gas emission prediction using Voronoi diagrams and importance sampling. Environmental Modelling & Software. 2009;**24**(10):1223-1232

[37] Lelieveld J, Hoor P, Jöckel P, Pozzer A, Hadjinicolaou P, Cammas JP, et al. Severe ozone air pollution in the Persian Gulf region. Atmospheric Chemistry and Physics. 2009;**9**:1393-1406

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[39] Yusuf RO. Methane Emission Inventory and Forecasting in Malaysia. Universiti Teknologi Malaysia; 2013

[40] Cai Y et al. Geological controls on prediction of coalbed methane of No. 3 coal seam in southern Qinshui Basin, North China. International Journal of Coal Geology. 2011;**88**(2-3):101-112

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[44] Karacan CÖ et al. Coal mine methane: A review of capture and utilization practices with benefits to mining safety and to greenhouse gas reduction. International Journal of Coal Geology. 2011;**86**(2-3):121-156

[45] Su S et al. Fugitive coal mine methane emissions at five mining areas in China. Atmospheric Environment. 2011;**45**(13):2220-2232

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[47] Wang S et al. Methane emission by plant communities in an alpine meadow on the Qinghai-Tibetan plateau: A new experimental study of alpine meadows and oat pasture. Biology Letters. 2009;**5**(4):535-538

[48] Shahabadi MB, Yerushalmi L, Haghighat F. Estimation of greenhouse gas generation in wastewater treatment plants–model development and application. Chemosphere. 2010;**78**(9):1085-1092

[49] Guisasola A et al. Development of a model for assessing methane formation in rising main sewers. Water Research. 2009;**43**(11):2874-2884

[50] Etheridge D et al. Historic CH4 Records from Antarctic and Greenland Ice Cores, Antarctic Firn Data, and Archived Air Samples from Cape Grim, Tasmania. Trends: A Compendium of Data on Global Change. Oak Ridge, Tenn., USA: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy; 2002

**65**

2006

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation*

[61] Xiaohong Z, Jia H, Junxin C. Study on mitigation strategies of methane emission from rice paddies in the implementation of ecological agriculture. Energy Procedia.

[62] Wassmann R, Hosen Y, Sumfleth K. Reducing Methane Emissions from Irrigated Rice. International Food Policy

Research Institute (IFPRI). 2009

Korea. Ambio. 1996:289-291

Small Municipal Utilities

[66] Wilkinson P et al. Public health benefits of strategies to reduce greenhouse-gas emissions: Household energy. The Lancet. 2009;**374**(9705):1917-1929

[67] DOE-ITP. Improving process heating system performance: A sourcebook for industry. In: US

Department of Energy, Office of Energy Efficiency and Renewable Energy; 2007

[68] Prindle W et al. Energy efficiency's Next Generation: Innovation at the State Level. Report 2003 (E031). Washington, DC: American Council for an Energy-

Efficient Economy; 2003

Google Patents. 2003

[69] Prindle J. Videophone and Videoconferencing Apparatus and Method for a Video Game Console.

[70] Zubair M et al. Evaluation of air pollution sources in selected zone of textile industries in Pakistan. Environmental Engineering and Management Journal. 2017;**16**(2)

[63] Shin Y-K et al. Mitigation options for methane emission from rice fields in

[64] Yusuf RO et al. Methane emission by sectors: A comprehensive review of emission sources and mitigation methods. Renewable and Sustainable Energy Reviews. 2012;**16**(7):5059-5070

[65] Fernandez CZ, Kulkarni K, Polgar S, Schneider M, Webster SS. A Guide for

2011;**5**:2474-2480

*DOI: http://dx.doi.org/10.5772/intechopen.93104*

Annesi-Maesano I. Air pollution: From sources of emissions to health effects.

[52] Festy B. La pollution atmosphérique

[53] Fuglestvedt J et al. Implications of possible interpretations of 'greenhouse gas balance' in the Paris agreement. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[54] Michaelowa A et al. Interaction between Art. 6 of the Paris Agreement and the Montreal Protocol/Kigali

[55] Petrescu RV et al. NASA sees first in 2018 the direct proof of ozone hole recovery. Journal of Aircraft and Spacecraft Technology. 2018;**2**(1):53-64

[56] Lackner KS et al. Carbon dioxide capture and mitigation of carbon dioxide emissions. Google Patents. 2011

[57] Dietz T, Stern PC, Dan A. How deliberation affects stated willingness to pay for mitigation of carbon dioxide emissions: An experiment. Land Economics. 2009;**85**(2):329-347

[58] Warmuzinski K. Harnessing methane emissions from coal mining. Process Safety and Environmental Protection. 2008;**86**(5):315-320

[59] Gas GAN-CG. Emissions: 1990- 2020. Office of Atmospheric Programs Climate Change Division. Washington: US Environmental Protection Agency;

[60] Initiative GGM. Underground Coal Mine Methane Recovery and Use

Opportunities. 2008

[51] Pénard-Morand C,

1997;**8**(2):231-241

Breathe. 2004;**1**(2):108-119

urbaine: Sources, polluants et évolution. Energies Santé (Paris).

2018;**376**(2119):20160445

Amendment. 2019

*Industrial Air Emission Pollution: Potential Sources and Sustainable Mitigation DOI: http://dx.doi.org/10.5772/intechopen.93104*

[51] Pénard-Morand C, Annesi-Maesano I. Air pollution: From sources of emissions to health effects. Breathe. 2004;**1**(2):108-119

*Environmental Emissions*

2008;**1**:117-120

2010;**25**(4):456-468

2009;**24**(10):1223-1232

2009;**9**:1393-1406

2002;**57**(3-4):177-210

1999;**38**(6):1453-1459

2011;**89**(1):81-91

[37] Lelieveld J, Hoor P, Jöckel P, Pozzer A, Hadjinicolaou P, Cammas JP, et al. Severe ozone air pollution in the Persian Gulf region. Atmospheric Chemistry and Physics.

[38] Wuebbles DJ, Hayhoe K. Atmospheric methane and global change. Earth-Science Reviews.

[39] Yusuf RO. Methane Emission Inventory and Forecasting in Malaysia. Universiti Teknologi Malaysia; 2013

[40] Cai Y et al. Geological controls on prediction of coalbed methane of No. 3 coal seam in southern Qinshui Basin, North China. International Journal of Coal Geology. 2011;**88**(2-3):101-112

[41] Makhov G, Bazhin N. Methane emission from lakes. Chemosphere.

[42] Zhang G et al. Effect of drainage in the fallow season on reduction of CH4 production and emission from permanently flooded rice fields. Nutrient Cycling in Agroecosystems.

[43] Lin H-C, Fukushima Y. Rice cultivation methods and their sustainability aspects: Organic and

University of Science & Engineering.

conventional rice production in industrialized tropical monsoon Asia with a dual cropping system. Sustainability. 2016;**8**(6):529

[44] Karacan CÖ et al. Coal mine methane: A review of capture and utilization practices with benefits to mining safety and to greenhouse gas reduction. International Journal of Coal

Geology. 2011;**86**(2-3):121-156

[45] Su S et al. Fugitive coal mine methane emissions at five mining areas in China. Atmospheric Environment.

[46] Wales AD, Allen VM, Davies RH. Chemical treatment of animal feed and water for the control of salmonella. Foodborne Pathogens and Disease.

[47] Wang S et al. Methane emission by plant communities in an alpine meadow on the Qinghai-Tibetan plateau: A new experimental study of alpine meadows and oat pasture. Biology Letters.

[48] Shahabadi MB, Yerushalmi L, Haghighat F. Estimation of greenhouse

treatment plants–model development and application. Chemosphere.

[49] Guisasola A et al. Development of a model for assessing methane formation in rising main sewers. Water Research.

[50] Etheridge D et al. Historic CH4 Records from Antarctic and Greenland Ice Cores, Antarctic Firn Data, and Archived Air Samples from Cape Grim, Tasmania. Trends: A Compendium of Data on Global Change. Oak Ridge, Tenn., USA: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of

gas generation in wastewater

2010;**78**(9):1085-1092

2009;**43**(11):2874-2884

Energy; 2002

2011;**45**(13):2220-2232

2010;**7**(1):3-15

2009;**5**(4):535-538

[35] Rodríguez R, Lombardía C. Analysis of methane emissions in a tunnel excavated through carboniferous strata based on underground coal mining experience. Tunnelling and Underground Space Technology.

[36] Mackie K, Cooper C. Landfill gas emission prediction using Voronoi diagrams and importance sampling. Environmental Modelling & Software.

**64**

[52] Festy B. La pollution atmosphérique urbaine: Sources, polluants et évolution. Energies Santé (Paris). 1997;**8**(2):231-241

[53] Fuglestvedt J et al. Implications of possible interpretations of 'greenhouse gas balance' in the Paris agreement. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2018;**376**(2119):20160445

[54] Michaelowa A et al. Interaction between Art. 6 of the Paris Agreement and the Montreal Protocol/Kigali Amendment. 2019

[55] Petrescu RV et al. NASA sees first in 2018 the direct proof of ozone hole recovery. Journal of Aircraft and Spacecraft Technology. 2018;**2**(1):53-64

[56] Lackner KS et al. Carbon dioxide capture and mitigation of carbon dioxide emissions. Google Patents. 2011

[57] Dietz T, Stern PC, Dan A. How deliberation affects stated willingness to pay for mitigation of carbon dioxide emissions: An experiment. Land Economics. 2009;**85**(2):329-347

[58] Warmuzinski K. Harnessing methane emissions from coal mining. Process Safety and Environmental Protection. 2008;**86**(5):315-320

[59] Gas GAN-CG. Emissions: 1990- 2020. Office of Atmospheric Programs Climate Change Division. Washington: US Environmental Protection Agency; 2006

[60] Initiative GGM. Underground Coal Mine Methane Recovery and Use Opportunities. 2008

[61] Xiaohong Z, Jia H, Junxin C. Study on mitigation strategies of methane emission from rice paddies in the implementation of ecological agriculture. Energy Procedia. 2011;**5**:2474-2480

[62] Wassmann R, Hosen Y, Sumfleth K. Reducing Methane Emissions from Irrigated Rice. International Food Policy Research Institute (IFPRI). 2009

[63] Shin Y-K et al. Mitigation options for methane emission from rice fields in Korea. Ambio. 1996:289-291

[64] Yusuf RO et al. Methane emission by sectors: A comprehensive review of emission sources and mitigation methods. Renewable and Sustainable Energy Reviews. 2012;**16**(7):5059-5070

[65] Fernandez CZ, Kulkarni K, Polgar S, Schneider M, Webster SS. A Guide for Small Municipal Utilities

[66] Wilkinson P et al. Public health benefits of strategies to reduce greenhouse-gas emissions: Household energy. The Lancet. 2009;**374**(9705):1917-1929

[67] DOE-ITP. Improving process heating system performance: A sourcebook for industry. In: US Department of Energy, Office of Energy Efficiency and Renewable Energy; 2007

[68] Prindle W et al. Energy efficiency's Next Generation: Innovation at the State Level. Report 2003 (E031). Washington, DC: American Council for an Energy-Efficient Economy; 2003

[69] Prindle J. Videophone and Videoconferencing Apparatus and Method for a Video Game Console. Google Patents. 2003

[70] Zubair M et al. Evaluation of air pollution sources in selected zone of textile industries in Pakistan. Environmental Engineering and Management Journal. 2017;**16**(2)

**67**

**Chapter 5**

**Abstract**

Methods to Reduce Mercury and

Nitrogen Oxides Emissions from

The chapter presents the issue of reducing mercury and nitrogen oxides emissions

from the flue gas of coal-fired boilers. The issue is particularly relevant due to the stricter regulations regarding exhaust gas purity. A brief review of the methods for reducing Hg and NOx emissions has been made, pointing out their pros and cons. Against this background, the results of the authors' own research on the injection of selected oxidants into flue gases to remove both of these pollutants are presented. The injection of sodium chlorite solution into the flue gas (400 MWe lignite fired unit) upstream the wet flue gas desulphurization (WFGD) absorber contributed to the oxidation of both metallic mercury and nitric oxide and enhanced their removal efficiency. The results of tests on lignite and hard coal flue gases indicate that in order to reduce the unfavorable phenomenon of mercury re-emission from WFGD absorbers, in some cases, it is necessary to add selected chemical compounds (e.g., sulfides) to the desulfurization system. The results of field tests for flue gas from lignite (400 MWe unit) and hard coal-fired boilers (195 and 220 MWe units) confirmed the usefulness of oxidizer injection technology to reduce mercury emissions below the

**Keywords:** Hg emissions, NOx emissions, combustion, industrial pollution,

In nature mercury is present in trace amounts only; due to its toxicity and the ability to join various natural cycles, it poses a threat to human health and life. Mercury exposure, even in small amounts, poses a threat to both people and the environment. A global study commissioned by United Nations Environment

Programme (UNEP) confirmed the high environmental impact of mercury, entirely justifying the actions implemented to combat its spread on the international level. In recent years, the European Union has been systematically tightening standards

According to UNEP data, in 2015 the global emissions from anthropogenic sources amounted to 2220 tons of mercury, accounting for almost 30% of the total atmospheric emissions of mercury. The remaining 70% comes from environmental processes and contemporary natural sources [1]. The technological processes with

for permissible mercury concentrations in atmospheric air.

Coal Combustion Processes

*Maria Jędrusik, Dariusz Łuszkiewicz* 

*and Arkadiusz Świerczok*

level required by BAT conclusions.

heavy metals

**1. Introduction**

#### **Chapter 5**

## Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes

*Maria Jędrusik, Dariusz Łuszkiewicz and Arkadiusz Świerczok*

#### **Abstract**

The chapter presents the issue of reducing mercury and nitrogen oxides emissions from the flue gas of coal-fired boilers. The issue is particularly relevant due to the stricter regulations regarding exhaust gas purity. A brief review of the methods for reducing Hg and NOx emissions has been made, pointing out their pros and cons. Against this background, the results of the authors' own research on the injection of selected oxidants into flue gases to remove both of these pollutants are presented. The injection of sodium chlorite solution into the flue gas (400 MWe lignite fired unit) upstream the wet flue gas desulphurization (WFGD) absorber contributed to the oxidation of both metallic mercury and nitric oxide and enhanced their removal efficiency. The results of tests on lignite and hard coal flue gases indicate that in order to reduce the unfavorable phenomenon of mercury re-emission from WFGD absorbers, in some cases, it is necessary to add selected chemical compounds (e.g., sulfides) to the desulfurization system. The results of field tests for flue gas from lignite (400 MWe unit) and hard coal-fired boilers (195 and 220 MWe units) confirmed the usefulness of oxidizer injection technology to reduce mercury emissions below the level required by BAT conclusions.

**Keywords:** Hg emissions, NOx emissions, combustion, industrial pollution, heavy metals

#### **1. Introduction**

In nature mercury is present in trace amounts only; due to its toxicity and the ability to join various natural cycles, it poses a threat to human health and life. Mercury exposure, even in small amounts, poses a threat to both people and the environment. A global study commissioned by United Nations Environment Programme (UNEP) confirmed the high environmental impact of mercury, entirely justifying the actions implemented to combat its spread on the international level. In recent years, the European Union has been systematically tightening standards for permissible mercury concentrations in atmospheric air.

According to UNEP data, in 2015 the global emissions from anthropogenic sources amounted to 2220 tons of mercury, accounting for almost 30% of the total atmospheric emissions of mercury. The remaining 70% comes from environmental processes and contemporary natural sources [1]. The technological processes with

the largest share in mercury emissions are gold production, 38%; coal combustion, 21%; nonferrous metallurgy, 15%; cement plants, 11%; waste incineration plants processing mercury-containing waste, 7%; and combustion of other fuels, including biomass, 3%. Analyzing data on mercury emissions in the respective continents, it can be stated that we find the highest ones in Asia, with about 1084 tons p.a.; in South America, about 409 tons p.a.; Sub-Saharan Africa, 360 tons p.a.; and in the European Union, with 77.2 tons p.a. [1]. Therefore, we can see that the processes of burning fossil fuels form one of the most significant sources of global atmospheric emissions of mercury.

Research on Polish coals [2] demonstrates that the average mercury content in hard coal ranges from 50 to 150 ppb and 120 to 370 ppb in the case of lignite. For comparison, the mercury content of American coals is about 30–670 ppb, with the average content for hard coal of 70 and 118 ppb for lignite. The mercury content in furnace waste indicates that it is mainly found in fly ash and only a small part of it in slag. Literature data indicates that in the result of burning coal, approximately 30–75% of the mercury, contained in the fuel, will be released into the atmosphere [3].

In the process of coal combustion, a number of chemical reactions occur that lead to the decomposition of all chemical compounds containing mercury. In the result of these processes, at a temperature above 600°C, only the metallic mercury Hg<sup>0</sup> in the form of vapor will be present in the exhaust gas [4]. As the exhaust gas is cooled below 540°C [5], this mercury can be oxidized by gas phase components such as NO2, HCl, SO2, H2O, and fly ash, producing various compounds of mercury (**Table 1**).

It was noticed that when burning coals containing significant amounts of chlorine, bromine, or iodine, the concentration of oxidized mercury increases with simultaneous decrease in concentration of metallic mercury. In the process of burning carbons containing chlorine, bromine, or iodine, the process of mercury oxidation is such that during this combustion salts containing chlorine, iodine or bromine is decomposed into HCl, HI, and HBr, whereby 0.5 ÷ 9% of these compounds are further decomposed to CL2, I2, and Br2. These react with metallic mercury to form HgCl2, HgBr2, and HgI2 salts, respectively, which are stable at high temperatures in vapor form. Oxidized mercury is removed from the flue gas both in dust collectors and in wet and semidry flue gas desulfurization units [6]. However, the efficiency of removal of metallic Hg<sup>0</sup> in the aforementioned devices is low.


**69**

**Table 2.**

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

The degree of the removal of mercury and its compounds depends mainly on the degree of transition of metallic mercury to oxidized mercury, with HgCl2 accounting for the main part of oxidized mercury. The value of Hg emissions depends on the combustion process and the method of exhaust gas purification; the mercury removal efficiency in an electrostatic precipitator is 30–40%, while in a wet desulfurization plant, as much as 80–90% of Hg2+ (divalent) mercury and mercury adsorbed by the solid phase will be removed, but in the case of

The proportions between individual forms of mercury in the exhaust gas downstream the boiler depend mainly on the type of furnace and fuel characteristics (mercury, halides, and ash content of coal). The content of halides (fluorine, bromine, iodine, and chlorine) and mercury in fuel has the greatest impact on the amount of Hg2+, while the ash content determines the amount of Hg(p) [7]. For example, the proportions between elemental mercury, oxidized mercury, and ash-bound mercury in flue gas downstream of a pulverized coal boiler are on average 56% (8–94%), 34% (5–82%), and 10% (1–28%), respectively [7]. The type of furnace is not without significance for the mercury speciation in the exhaust gas. Circulating fluidized bed boilers generate the highest amount of Hg(p) (up to 65%

defined as HgT

The European Commission (on July 31, 2017) established conclusions on the best

extended contact time between gaseous mercury and fly ash and the low tempera-

available techniques (BAT) for large combustion plants (LCP). BAT conclusions tighten the regulations related to the emissions from combustion processes, including nitrogen and sulfur oxides, and introduce mercury emission limits (that were not present in the EU till that date). **Table 2** contains the permissible concentrations of mercury and nitrogen oxides in the exhaust gas, resulting from the BAT conclusions. BAT conclusions include ranges of emission limit values for mercury and nitrogen oxides in exhaust gases, with maximum concentration values that will apply from 2021 onwards. Permissible mercury concentrations in exhaust gases resulting from

ing on the status of the source. For existing sources with a capacity of >300 MWt,

lignite. Concentrations are converted to standard USR means conditions: (dry gas at a temperature of 273.15 K and a pressure of 101.3 kPa, calculated for oxygen content in

**Oxidant Oxidizing potential, V Oxidizing potential relative to oxygen**

<sup>−</sup> 0.786 1.13

Oxygen, O2 0.695 1.00 Oxygen radical, O 1.229 1.77 Chlorine, Cl2 1.360 1.96 Hydrogen peroxide, H2O2 1.760 2.53 Ozone, O3 2.080 2.99 Chlorine (I) anion, ClO<sup>−</sup> 0.890 1.28

Hypochlorous acid, HClO 1.630 2.35

= Hg0

+ Hg2+ + Hg(p)) due to the

. These values vary depend-

USR for

USR for lignite. For new sources with

USR for hard coal and 1–4 μg/m3

mercury, far less is removed, with a removal efficiency of just

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

of the so-called total mercury Hg<sup>T</sup>

they are 1–4 μg/m3

the flue gas O2 = 6 %).

Chlorate (III) anion, ClO2

*Oxidation potentials of oxidants used [31].*

ture of the exhaust gas downstream of the boiler [7].

BAT conclusions [8] are referred to as total mercury HgT

a capacity of >300 MWt, they are 1–2 μg/m3

USR for hard coal and 1–7 μg/m3

elemental Hg<sup>0</sup>

26.6% [3].

**Table 1.**

*Mercury compounds in flue gases from coal combustion processes.*

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

The degree of the removal of mercury and its compounds depends mainly on the degree of transition of metallic mercury to oxidized mercury, with HgCl2 accounting for the main part of oxidized mercury. The value of Hg emissions depends on the combustion process and the method of exhaust gas purification; the mercury removal efficiency in an electrostatic precipitator is 30–40%, while in a wet desulfurization plant, as much as 80–90% of Hg2+ (divalent) mercury and mercury adsorbed by the solid phase will be removed, but in the case of elemental Hg<sup>0</sup> mercury, far less is removed, with a removal efficiency of just 26.6% [3].

The proportions between individual forms of mercury in the exhaust gas downstream the boiler depend mainly on the type of furnace and fuel characteristics (mercury, halides, and ash content of coal). The content of halides (fluorine, bromine, iodine, and chlorine) and mercury in fuel has the greatest impact on the amount of Hg2+, while the ash content determines the amount of Hg(p) [7]. For example, the proportions between elemental mercury, oxidized mercury, and ash-bound mercury in flue gas downstream of a pulverized coal boiler are on average 56% (8–94%), 34% (5–82%), and 10% (1–28%), respectively [7]. The type of furnace is not without significance for the mercury speciation in the exhaust gas. Circulating fluidized bed boilers generate the highest amount of Hg(p) (up to 65% of the so-called total mercury Hg<sup>T</sup> defined as HgT = Hg0 + Hg2+ + Hg(p)) due to the extended contact time between gaseous mercury and fly ash and the low temperature of the exhaust gas downstream of the boiler [7].

The European Commission (on July 31, 2017) established conclusions on the best available techniques (BAT) for large combustion plants (LCP). BAT conclusions tighten the regulations related to the emissions from combustion processes, including nitrogen and sulfur oxides, and introduce mercury emission limits (that were not present in the EU till that date). **Table 2** contains the permissible concentrations of mercury and nitrogen oxides in the exhaust gas, resulting from the BAT conclusions. BAT conclusions include ranges of emission limit values for mercury and nitrogen oxides in exhaust gases, with maximum concentration values that will apply from 2021 onwards. Permissible mercury concentrations in exhaust gases resulting from BAT conclusions [8] are referred to as total mercury HgT . These values vary depending on the status of the source. For existing sources with a capacity of >300 MWt, they are 1–4 μg/m3 USR for hard coal and 1–7 μg/m3 USR for lignite. For new sources with a capacity of >300 MWt, they are 1–2 μg/m3 USR for hard coal and 1–4 μg/m3 USR for lignite. Concentrations are converted to standard USR means conditions: (dry gas at a temperature of 273.15 K and a pressure of 101.3 kPa, calculated for oxygen content in the flue gas O2 = 6 %).


#### **Table 2.**

*Oxidation potentials of oxidants used [31].*

*Environmental Emissions*

emissions of mercury.

the atmosphere [3].

pounds of mercury (**Table 1**).

[6]. However, the efficiency of removal of metallic Hg<sup>0</sup>

*Mercury compounds in flue gases from coal combustion processes.*

**No. Name Symbol Boiling point** 1. Mercury Hg 356.6°C 2. Mercuric chloride HgCl2 302.0°C 3. Mercuric bromide HgBr2 322.0°C 4. Mercury(II) iodide HgI2 354.0°C 5. Mercurous oxide Hg2O Decomposes at >100°C 6. Mercuric oxide HgO Decomposes at >500°C 7. Mercury(I) carbonate Hg2CO3 Decomposes at >130°C 8. Mercury(II) nitrate Hg(NO3)2 Melting point 79°C

9. Mercury(II) sulfate HgSO4 Decomposes before reaching liquid phase

mercury Hg<sup>0</sup>

devices is low.

the largest share in mercury emissions are gold production, 38%; coal combustion, 21%; nonferrous metallurgy, 15%; cement plants, 11%; waste incineration plants processing mercury-containing waste, 7%; and combustion of other fuels, including biomass, 3%. Analyzing data on mercury emissions in the respective continents, it can be stated that we find the highest ones in Asia, with about 1084 tons p.a.; in South America, about 409 tons p.a.; Sub-Saharan Africa, 360 tons p.a.; and in the European Union, with 77.2 tons p.a. [1]. Therefore, we can see that the processes of burning fossil fuels form one of the most significant sources of global atmospheric

Research on Polish coals [2] demonstrates that the average mercury content in hard coal ranges from 50 to 150 ppb and 120 to 370 ppb in the case of lignite. For comparison, the mercury content of American coals is about 30–670 ppb, with the average content for hard coal of 70 and 118 ppb for lignite. The mercury content in furnace waste indicates that it is mainly found in fly ash and only a small part of it in slag. Literature data indicates that in the result of burning coal, approximately 30–75% of the mercury, contained in the fuel, will be released into

In the process of coal combustion, a number of chemical reactions occur that lead to the decomposition of all chemical compounds containing mercury. In the result of these processes, at a temperature above 600°C, only the metallic

exhaust gas is cooled below 540°C [5], this mercury can be oxidized by gas phase components such as NO2, HCl, SO2, H2O, and fly ash, producing various com-

It was noticed that when burning coals containing significant amounts of chlorine, bromine, or iodine, the concentration of oxidized mercury increases with simultaneous decrease in concentration of metallic mercury. In the process of burning carbons containing chlorine, bromine, or iodine, the process of mercury oxidation is such that during this combustion salts containing chlorine, iodine or bromine is decomposed into HCl, HI, and HBr, whereby 0.5 ÷ 9% of these compounds are further decomposed to CL2, I2, and Br2. These react with metallic mercury to form HgCl2, HgBr2, and HgI2 salts, respectively, which are stable at high temperatures in vapor form. Oxidized mercury is removed from the flue gas both in dust collectors and in wet and semidry flue gas desulfurization units

in the form of vapor will be present in the exhaust gas [4]. As the

in the aforementioned

**68**

**Table 1.**

BAT conclusions include the range of mercury emission limit values for exhaust gases while specifying maximum concentration values that will apply from August 18, 2021 onwards. The lower values indicate levels that can be obtained using best available techniques, and as long as these values are not required now, it can be expected that existing and new coal units will have to achieve them in near future [8]. This means that users of combustion plants should seek for methods to achieve lower emission levels resulting from the BAT conclusions. The implementation of BAT conclusions thus forms a significant challenge for coal energy in Europe and in particular for the Polish energy sector. The introduction of emission limits also necessitates the addition of HgT measurement devices to the pollution monitoring system [8].

BAT conclusions also reduce the permissible levels of nitrogen oxides (NOx) emissions. For existing sources, fired with hard coal and lignite, with a capacity of >300 MWt, these amount to 85 (65)–150 mg/m3 , and for new sources with a capacity of >300 MWt to 50 (65)–85 mg/m3 in standard conditions.

The above provisions are associated with the need to implement *selective catalytic reduction* (SCR) and *selective non-catalytic reduction* (SNCR) techniques as well as other techniques, including integrated exhaust gas treatment (*multipollutant technologies*), in which a single device is applied to remove at least two pollutants. In this study, we would like to point to the possibility of such integrated flue gas treatment in absorbers of the wet flue gas desulfurization method. The wet limestone method is a common SO2 removal technology used in power plants both in Europe and worldwide. The desulfurization efficiency of this method ranges from 90 to 95%. This technology is also very popular in Polish conditions, accounting for some 90% of the desulfurization installations.

#### **2. Methods for reducing mercury emissions**

#### **2.1 Primary methods**

Enrichment of coal prior to the combustion process, e.g., by removing pyrite, can significantly reduce mercury emissions. It is estimated that 65–70% of mercury in Polish coals occurs in combination with pyrite.

Coal enrichment methods are mainly based on physical separation of the mineral substance and involve the use of density differences (gravitational separation) or differences in the wettability of the components (flotation).

One of the methods that do apply dry gravitational separation is the removal of pyrite in purpose-modernized coal mills. The technology is offered by Hansom [9].

Primary methods also include changing the combustion process. For example fluidized bed furnaces to lower the exhaust gas temperature and ash grain composition or using of low emissions burners to lower exhaust gas temperature. Another solution is to replace the coal used for combustion and mixing high Hg and S content coals with those with lower contents of these elements [10]. What is also applied is the addition of halides, in the form of bromine, iodine, and chlorine salts, to the burning coal [11]. The oxidizing properties of these compounds contribute to the increase in the proportion of oxidized mercury in the exhaust gases, which in turn contributes to its more effective retention in existing aftertreatment devices. Unfortunately, these methods cannot guarantee the reduction of mercury to the level required by BAT conclusions.

#### **2.2 Secondary methods**

The degree of the removal of mercury and its compounds depends mainly on the degree of transition of metallic mercury to oxidized mercury. Secondary methods

**71**

**Figure 1.**

*desulfurization installation.*

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

consist mainly of removing oxidized mercury adsorbed on ash particles or other adsorbent, e.g., activated carbon, in its form bound with particulates—Hg(p).

methods. They rely on binding of oxidized forms of mercury on the surface of adsorbents. What they use is the affinity of mercury vapors to various adsorbents. The most common adsorber is activated carbon in powdered form (powdered

typical form of carbon, it is necessary to impregnate this medium with sulfur, iodine, chlorine, or bromine to improve the efficiency of mercury vapor retention. This increases the efficiency of mercury oxidation and its adsorption on PAC particles. Studies demonstrated that ordinary activated carbon can retain up to 80% of mercury in a higher oxidation state but only some 40–50% of elemental mercury. In contrast, carbon impregnated with sulfur, for example, adsorbs over 80% Hg0

activated carbon). However, due to the limited efficiency of Hg0

and the iodine impregnated carbon virtually 100% [12].

*2.2.1 Injection of activated carbon (PAC) in exhaust gases*

makes it necessary to dispose ash from two different locations [13].

*oxidation of mercury*

Another solution for the injection of activated carbon into exhaust gases is the sorbent injection upstream the air preheater into the zone with a much higher temperature than in the solutions used so far downstream the air preheater or the electrostatic precipitator, i.e., the Alstom Mer-Cure™ technology [14] (**Figure 3**).

It was found, based on the research, that in flue gas denitrification installations

*Diagram of activated carbon injection technology upstream of the ESP; APH—air heater and FGD—flue gas* 

*2.2.2 The use of systems for catalytic reduction of nitrogen oxides (SCR) for the* 

based on the selective catalytic reduction method, the oxidation of Hg0

An important group of secondary methods are the adsorptive mercury removal

Activated carbon is usually injected into the exhaust gas duct before the ESP or fabric filter (**Figure 1**). This technology is used in waste incineration facilities and coal-fired power plants. The effectiveness of this method depends primarily on the type and structure of PAC, the chemical properties of the sorbent surface, the amount of injected coal, and the temperature of the exhaust gas. The main disadvantage of this technology is the increase in the carbon content of ash, which significantly limits the possibilities of ash utilization. Sometimes it can also reduce dust collection efficiency, especially when particles of submicron scale are considered. To tackle this issue, activated carbon injection downstream the ESP and further exhaust gas purification in the fabric filter are applied (**Figure 2**). However, this

reduction of this

mercury

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

#### *Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

consist mainly of removing oxidized mercury adsorbed on ash particles or other adsorbent, e.g., activated carbon, in its form bound with particulates—Hg(p).

An important group of secondary methods are the adsorptive mercury removal methods. They rely on binding of oxidized forms of mercury on the surface of adsorbents. What they use is the affinity of mercury vapors to various adsorbents. The most common adsorber is activated carbon in powdered form (powdered activated carbon). However, due to the limited efficiency of Hg0 reduction of this typical form of carbon, it is necessary to impregnate this medium with sulfur, iodine, chlorine, or bromine to improve the efficiency of mercury vapor retention. This increases the efficiency of mercury oxidation and its adsorption on PAC particles. Studies demonstrated that ordinary activated carbon can retain up to 80% of mercury in a higher oxidation state but only some 40–50% of elemental mercury. In contrast, carbon impregnated with sulfur, for example, adsorbs over 80% Hg0 and the iodine impregnated carbon virtually 100% [12].

#### *2.2.1 Injection of activated carbon (PAC) in exhaust gases*

Activated carbon is usually injected into the exhaust gas duct before the ESP or fabric filter (**Figure 1**). This technology is used in waste incineration facilities and coal-fired power plants. The effectiveness of this method depends primarily on the type and structure of PAC, the chemical properties of the sorbent surface, the amount of injected coal, and the temperature of the exhaust gas. The main disadvantage of this technology is the increase in the carbon content of ash, which significantly limits the possibilities of ash utilization. Sometimes it can also reduce dust collection efficiency, especially when particles of submicron scale are considered.

To tackle this issue, activated carbon injection downstream the ESP and further exhaust gas purification in the fabric filter are applied (**Figure 2**). However, this makes it necessary to dispose ash from two different locations [13].

Another solution for the injection of activated carbon into exhaust gases is the sorbent injection upstream the air preheater into the zone with a much higher temperature than in the solutions used so far downstream the air preheater or the electrostatic precipitator, i.e., the Alstom Mer-Cure™ technology [14] (**Figure 3**).

#### *2.2.2 The use of systems for catalytic reduction of nitrogen oxides (SCR) for the oxidation of mercury*

It was found, based on the research, that in flue gas denitrification installations based on the selective catalytic reduction method, the oxidation of Hg0 mercury

#### **Figure 1.**

*Diagram of activated carbon injection technology upstream of the ESP; APH—air heater and FGD—flue gas desulfurization installation.*

*Environmental Emissions*

addition of HgT

>300 MWt, these amount to 85 (65)–150 mg/m3

**2. Methods for reducing mercury emissions**

in Polish coals occurs in combination with pyrite.

or differences in the wettability of the components (flotation).

ity of >300 MWt to 50 (65)–85 mg/m3

of the desulfurization installations.

**2.1 Primary methods**

**2.2 Secondary methods**

BAT conclusions include the range of mercury emission limit values for exhaust gases while specifying maximum concentration values that will apply from August 18, 2021 onwards. The lower values indicate levels that can be obtained using best available techniques, and as long as these values are not required now, it can be expected that existing and new coal units will have to achieve them in near future [8]. This means that users of combustion plants should seek for methods to achieve lower emission levels resulting from the BAT conclusions. The implementation of BAT conclusions thus forms a significant challenge for coal energy in Europe and in particular for the Polish energy sector. The introduction of emission limits also necessitates the

measurement devices to the pollution monitoring system [8].

The above provisions are associated with the need to implement *selective catalytic reduction* (SCR) and *selective non-catalytic reduction* (SNCR) techniques as well as other techniques, including integrated exhaust gas treatment (*multipollutant technologies*), in which a single device is applied to remove at least two pollutants. In this study, we would like to point to the possibility of such integrated flue gas treatment in absorbers of the wet flue gas desulfurization method. The wet limestone method is a common SO2 removal technology used in power plants both in Europe and worldwide. The desulfurization efficiency of this method ranges from 90 to 95%. This technology is also very popular in Polish conditions, accounting for some 90%

Enrichment of coal prior to the combustion process, e.g., by removing pyrite, can significantly reduce mercury emissions. It is estimated that 65–70% of mercury

Coal enrichment methods are mainly based on physical separation of the mineral substance and involve the use of density differences (gravitational separation)

One of the methods that do apply dry gravitational separation is the removal of pyrite in purpose-modernized coal mills. The technology is offered by Hansom [9]. Primary methods also include changing the combustion process. For example fluidized bed furnaces to lower the exhaust gas temperature and ash grain composition or using of low emissions burners to lower exhaust gas temperature. Another solution is to replace the coal used for combustion and mixing high Hg and S content coals with those with lower contents of these elements [10]. What is also applied is the addition of halides, in the form of bromine, iodine, and chlorine salts, to the burning coal [11]. The oxidizing properties of these compounds contribute to the increase in the proportion of oxidized mercury in the exhaust gases, which in turn contributes to its more effective retention in existing aftertreatment devices. Unfortunately, these methods cannot guarantee the reduction of mercury to the level required by BAT conclusions.

The degree of the removal of mercury and its compounds depends mainly on the degree of transition of metallic mercury to oxidized mercury. Secondary methods

in standard conditions.

, and for new sources with a capac-

BAT conclusions also reduce the permissible levels of nitrogen oxides (NOx) emissions. For existing sources, fired with hard coal and lignite, with a capacity of

**70**

**Figure 2.**

*Diagram of activated carbon injection technology downstream of the ESP; APH—air heater and FGD—flue gas desulfurization installation.*

**Figure 3.** *Diagram of the Mer-Cure™ technology for activated carbon injection; APH—air heater and FGD—flue gas desulphurization installation.*

to Hg2+ form occurs. The condition for this process, however, is the appropriate chlorine content in the flue gas. Typically, for hard coal, this content proves sufficient to trigger the oxidation process. Important for this process is the fact that the denitrification and oxidation reactions of mercury cannot occur simultaneously, because they depend on the same active centers. Research in industrial conditions indicates that the achievable degree of mercury oxidation is up to 78% [15].

When lignite is burned, the absence of chlorine in the flue gas causes oxidation reactions not to occur. In this case, NH4Cl injection upstream of the SCR catalyst is proposed to allow mercury oxidation in the catalyst (**Figure 4**). NH4Cl or NH4OH injection takes place in a zone with a temperature of about 370–420°C, and then activated carbon is added to the exhaust gas, after which the exhaust gas is directed

**73**

**Figure 5.**

*desulphurization installation.*

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

to a dust collector (ESP or fabric filter), and finally to the absorber of the wet

Based on numerous studies [17–23], it was found that with use of chloride additives, it is possible to achieve high efficiency of mercury vapor adsorption on

on chlorite and/or potassium permanganate into the exhaust duct upstream the

The degree of mercury oxidation in this technology depends on numerous parameters; the most important of them are flue gas temperature; flue gas composition, including the SO2, SO3, and NO concentrations; pH; and the chemical composition of fly ash. The main oxidized mercury compounds are HgO and Hg (NO3)2. Part of the oxidized mercury is adsorbed on fly ash particles and as Hg(p) is removed with dust in the ESP unit. The remaining Hg2+ mercury in gaseous form is retained in the WFGD absorber and is removed along with the wastewater.

Tests of mercury content in fly ash upstream of the electrostatic precipitator demonstrate that it is several times higher than the mercury content of coal, which indicates a high sorption capacity of fly ash [26, 27]. The mechanism of mercury adsorption is as follows: in the boiler (temperature of above 1400°C), mercury is in the form of metallic mercury vapors, while the chlorine (HCl) contained in the flue gas activates carbon particles in the ash, and as the flue gas cools down, Hg0 adsorbs in the chlorinated carbon pores and undergoes oxidation. If there is no HCl

Research on mercury content in fly ash from hard coal combustion in both pulverized coal and grate boilers indicates a higher Hg content in fine grains. In **Figure 6** we present the results of mercury content testing in individual fractions of

The sorption of mercury and its compounds depends significantly on the flue gas temperature and the content of unburned carbon in fly ash particles. Thus,

*Diagram of liquid additive injection technology upstream of the ESP: APH—air heater and FGD—flue gas* 

sorption on the ash particles, and the

The proposed method involves the injection of aqueous additive solutions based

*2.2.3 Injection of oxidizing additives and the use of fly ash as the adsorbent*

ordinary activated carbon or other sorbents (fly ash) [12, 24].

**2.3 Removal of oxidized mercury in flue gas purification devices**

*2.3.1 Removal of mercury in electrostatic precipitators*

(HBr, HI) in the flue gas, there is also no Hg0

fly ash grains from a pulverized coal boiler.

sorption of oxidized HgCl2 mercury is also low.

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

electrostatic precipitator [25] (**Figure 5**).

desulfurization method [16].

#### **Figure 4.**

*Diagram of mercury emission reduction technology for lignite-fired boilers: SCR—catalytic flue gas denitrification reactor; APH—air heater; and FGD—flue gas desulphurization installation.*

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

to a dust collector (ESP or fabric filter), and finally to the absorber of the wet desulfurization method [16].

#### *2.2.3 Injection of oxidizing additives and the use of fly ash as the adsorbent*

Based on numerous studies [17–23], it was found that with use of chloride additives, it is possible to achieve high efficiency of mercury vapor adsorption on ordinary activated carbon or other sorbents (fly ash) [12, 24].

The proposed method involves the injection of aqueous additive solutions based on chlorite and/or potassium permanganate into the exhaust duct upstream the electrostatic precipitator [25] (**Figure 5**).

The degree of mercury oxidation in this technology depends on numerous parameters; the most important of them are flue gas temperature; flue gas composition, including the SO2, SO3, and NO concentrations; pH; and the chemical composition of fly ash. The main oxidized mercury compounds are HgO and Hg (NO3)2. Part of the oxidized mercury is adsorbed on fly ash particles and as Hg(p) is removed with dust in the ESP unit. The remaining Hg2+ mercury in gaseous form is retained in the WFGD absorber and is removed along with the wastewater.

#### **2.3 Removal of oxidized mercury in flue gas purification devices**

#### *2.3.1 Removal of mercury in electrostatic precipitators*

Tests of mercury content in fly ash upstream of the electrostatic precipitator demonstrate that it is several times higher than the mercury content of coal, which indicates a high sorption capacity of fly ash [26, 27]. The mechanism of mercury adsorption is as follows: in the boiler (temperature of above 1400°C), mercury is in the form of metallic mercury vapors, while the chlorine (HCl) contained in the flue gas activates carbon particles in the ash, and as the flue gas cools down, Hg0 adsorbs in the chlorinated carbon pores and undergoes oxidation. If there is no HCl (HBr, HI) in the flue gas, there is also no Hg0 sorption on the ash particles, and the sorption of oxidized HgCl2 mercury is also low.

Research on mercury content in fly ash from hard coal combustion in both pulverized coal and grate boilers indicates a higher Hg content in fine grains. In **Figure 6** we present the results of mercury content testing in individual fractions of fly ash grains from a pulverized coal boiler.

The sorption of mercury and its compounds depends significantly on the flue gas temperature and the content of unburned carbon in fly ash particles. Thus,

#### **Figure 5.**

*Diagram of liquid additive injection technology upstream of the ESP: APH—air heater and FGD—flue gas desulphurization installation.*

*Environmental Emissions*

**Figure 2.**

**Figure 3.**

*desulphurization installation.*

*gas desulfurization installation.*

to Hg2+ form occurs. The condition for this process, however, is the appropriate chlorine content in the flue gas. Typically, for hard coal, this content proves sufficient to trigger the oxidation process. Important for this process is the fact that the denitrification and oxidation reactions of mercury cannot occur simultaneously, because they depend on the same active centers. Research in industrial conditions indicates that the achievable degree of mercury oxidation is up to 78% [15].

*Diagram of the Mer-Cure™ technology for activated carbon injection; APH—air heater and FGD—flue gas* 

*Diagram of activated carbon injection technology downstream of the ESP; APH—air heater and FGD—flue* 

When lignite is burned, the absence of chlorine in the flue gas causes oxidation reactions not to occur. In this case, NH4Cl injection upstream of the SCR catalyst is proposed to allow mercury oxidation in the catalyst (**Figure 4**). NH4Cl or NH4OH injection takes place in a zone with a temperature of about 370–420°C, and then activated carbon is added to the exhaust gas, after which the exhaust gas is directed

*Diagram of mercury emission reduction technology for lignite-fired boilers: SCR—catalytic flue gas denitrification reactor; APH—air heater; and FGD—flue gas desulphurization installation.*

**72**

**Figure 4.**

**Figure 6.** *Mercury content in individual fractions of fly ash from an OP-230 pulverized coal boiler.*

the removal efficiency of mercury and its compounds increases with the mercury oxidation efficiency and the increased dust removal efficiency, especially of fine particles.

#### *2.3.2 Removal of mercury in desulphurization installations*

#### *2.3.2.1 Mercury removal in absorbers of wet flue gas desulfurization installations*

Oxidized mercury compounds contained in the flue gas (mainly the HgCl2) are removed in FGD absorbers, whereas the Hg2+ reacts with the sulfides in the exhaust gas, e.g., with H2S, to form mercury sulfide HgS, which is then precipitated. We also know the phenomenon of mercury re-emission from flue gas desulfurization absorbers. If the sulfide content in the suspension is too low, a chemical reduction of Hg2+ to Hg0 may occur, resulting in higher concentration of metallic mercury downstream the absorber than upstream of it.

It is assumed that the efficiency of removing oxidized mercury in FGD absorbers reaches a value of up to 70%, while it can happen that almost all the oxidized mercury is removed in a dust collector, with only the metallic mercury reaching the absorber [6]. In this case, it is recommended to directly introduce oxidizing additive to the main FGD cycle [28].

#### *2.3.2.2 Removal of mercury in semidry flue gas desulfurization installations*

In semidry installations, the desulfurization process of the desulfurization reaction products (waste) remains dry. This process is implemented either by spraying lime milk in the upper part of the reactor (spray dryer) or using the so-called pneumatic reactor, where the sorbent and water are separately fed in its lower part. The resulting dry waste is most often recirculated, and the exhaust gases are dedusted in a fabric filter. The long residence time of sorbent particles in the reactor and the flow of exhaust gas through the filter cake in the bag filter allow for the additional benefit of removing quite a number of impurities, including mercury, provided that an appropriate sorbent is selected.

**75**

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

The semidry method using a pneumatic reactor integrated with a fabric filter for desulfurization of flue gas demonstrated a significant mercury removal efficiency of about 96%, when feeding additional activated carbon together with the primary

Methods for reducing nitrogen oxides from coal combustion in power plants can be divided into two main groups, i.e., the primary and secondary methods. Primary methods rely on the organization of the combustion process in the chamber, primarily through the use of low-emission burners, air staging, exhaust gas recirculation, or reduction of the combustion temperature (fluidized bed boilers). The second group of methods is the secondary method, i.e., the selective catalytic and

The latter group of secondary methods is applied in the integrated flue gas cleaning process. The basis for the operation of oxidative methods is the oxidation of sparingly soluble impurities in exhaust gases, i.e., nitric oxide and mercury to soluble forms, and their removal together with SO2 by means of absorption or condensation [30]. There are many oxidants that are applied in oxidative methods. The most recommended oxidizing agents are ozone (O3), hydrogen peroxide (H2O2), and numerous compounds of chlorine (NaClO, NaClO2, Ca(ClO)2, ClO2) [31]. Whenever a gaseous oxidant is used, it may be fed directly to the flue gas duct; in the case of liquid oxidants, the conditions necessary for their evaporation should be provided, or, alternatively, they can be used as an additive to the sorption liquid in the absorber [18]. Comparison of the oxidizing potential of individual oxidants

As you can see, ozone has the highest oxidation potential, and it has the valuable

advantage in that it enables oxidation of NO and NO2 to higher nitrogen oxides, while other oxidants oxidize it predominantly to NO2 only [31]. The fact that oxidation occurs in the gas phase, which affects the increase in reaction rate, is also significant. Oxidation methods allow for the simultaneous removal of nitrogen oxides, sulfur dioxide, and mercury from flue gases in a single installation, with an efficiency exceeding 90%. Due to the lower operating and investment costs, they form an alternative to the commonly used combination of SCR and FGD. The presence of dust in the flue gas affects the amount of oxidizer used, and therefore a high-performance dust collector should be used upstream of the installation. In the case of commercial pollutant removal installations, ozone is the main oxidizer used for nitrogen oxides. Removal of the reaction products of nitrogen oxides with ozone takes place by means of absorption, for example, by the Lextran [32, 33] and LoTOx methods [34–36]. In Lextran method ozone is added to the flue gas before the absorber feed by mixture of water and catalyst. In LoTOx method, ozone is

Another solution is to reduce pollution from flue gas with liquid oxidants. It involves their introduction into flue gas upstream of the wet or semidry flue gas desulphurization installations. Their task is to oxidize both the nitrogen oxide to NO2 and the metallic mercury to Hg2+. In the case of wet flue gas desulfurization installations, liquid oxidants may also be added to the sorption liquid tank. Hydrogen peroxide [37] is a very popular oxidant used in industry, having the valuable advantage in that it is not as harmful to the environment as chlorine compounds and, at the same time, it is relatively cheap. Exhaust gas treatment with hydrogen peroxide is an extremely promising process. Many researchers around the world are working to improve its effectiveness in relation to the oxidation of nitrogen oxides. Works are carried out

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

**3. Methods for reducing nitrogen oxides (NOx)**

non-catalytic reduction and oxidative methods.

with respect to oxygen is presented in **Table 2**.

introduced before FGD absorber.

sorbent (hydrated lime) [29].

The semidry method using a pneumatic reactor integrated with a fabric filter for desulfurization of flue gas demonstrated a significant mercury removal efficiency of about 96%, when feeding additional activated carbon together with the primary sorbent (hydrated lime) [29].

#### **3. Methods for reducing nitrogen oxides (NOx)**

*Environmental Emissions*

particles.

**Figure 6.**

of Hg2+ to Hg0

the removal efficiency of mercury and its compounds increases with the mercury oxidation efficiency and the increased dust removal efficiency, especially of fine

*Mercury content in individual fractions of fly ash from an OP-230 pulverized coal boiler.*

*2.3.2.1 Mercury removal in absorbers of wet flue gas desulfurization installations*

It is assumed that the efficiency of removing oxidized mercury in FGD absorbers reaches a value of up to 70%, while it can happen that almost all the oxidized mercury is removed in a dust collector, with only the metallic mercury reaching the absorber [6]. In this case, it is recommended to directly introduce

In semidry installations, the desulfurization process of the desulfurization reaction products (waste) remains dry. This process is implemented either by spraying lime milk in the upper part of the reactor (spray dryer) or using the so-called pneumatic reactor, where the sorbent and water are separately fed in its lower part. The resulting dry waste is most often recirculated, and the exhaust gases are dedusted in a fabric filter. The long residence time of sorbent particles in the reactor and the flow of exhaust gas through the filter cake in the bag filter allow for the additional benefit of removing quite a number of impurities, including mercury, provided that

*2.3.2.2 Removal of mercury in semidry flue gas desulfurization installations*

Oxidized mercury compounds contained in the flue gas (mainly the HgCl2) are removed in FGD absorbers, whereas the Hg2+ reacts with the sulfides in the exhaust gas, e.g., with H2S, to form mercury sulfide HgS, which is then precipitated. We also know the phenomenon of mercury re-emission from flue gas desulfurization absorbers. If the sulfide content in the suspension is too low, a chemical reduction

may occur, resulting in higher concentration of metallic mercury

*2.3.2 Removal of mercury in desulphurization installations*

downstream the absorber than upstream of it.

oxidizing additive to the main FGD cycle [28].

an appropriate sorbent is selected.

**74**

Methods for reducing nitrogen oxides from coal combustion in power plants can be divided into two main groups, i.e., the primary and secondary methods. Primary methods rely on the organization of the combustion process in the chamber, primarily through the use of low-emission burners, air staging, exhaust gas recirculation, or reduction of the combustion temperature (fluidized bed boilers). The second group of methods is the secondary method, i.e., the selective catalytic and non-catalytic reduction and oxidative methods.

The latter group of secondary methods is applied in the integrated flue gas cleaning process. The basis for the operation of oxidative methods is the oxidation of sparingly soluble impurities in exhaust gases, i.e., nitric oxide and mercury to soluble forms, and their removal together with SO2 by means of absorption or condensation [30]. There are many oxidants that are applied in oxidative methods. The most recommended oxidizing agents are ozone (O3), hydrogen peroxide (H2O2), and numerous compounds of chlorine (NaClO, NaClO2, Ca(ClO)2, ClO2) [31]. Whenever a gaseous oxidant is used, it may be fed directly to the flue gas duct; in the case of liquid oxidants, the conditions necessary for their evaporation should be provided, or, alternatively, they can be used as an additive to the sorption liquid in the absorber [18]. Comparison of the oxidizing potential of individual oxidants with respect to oxygen is presented in **Table 2**.

As you can see, ozone has the highest oxidation potential, and it has the valuable advantage in that it enables oxidation of NO and NO2 to higher nitrogen oxides, while other oxidants oxidize it predominantly to NO2 only [31]. The fact that oxidation occurs in the gas phase, which affects the increase in reaction rate, is also significant. Oxidation methods allow for the simultaneous removal of nitrogen oxides, sulfur dioxide, and mercury from flue gases in a single installation, with an efficiency exceeding 90%. Due to the lower operating and investment costs, they form an alternative to the commonly used combination of SCR and FGD. The presence of dust in the flue gas affects the amount of oxidizer used, and therefore a high-performance dust collector should be used upstream of the installation. In the case of commercial pollutant removal installations, ozone is the main oxidizer used for nitrogen oxides. Removal of the reaction products of nitrogen oxides with ozone takes place by means of absorption, for example, by the Lextran [32, 33] and LoTOx methods [34–36]. In Lextran method ozone is added to the flue gas before the absorber feed by mixture of water and catalyst. In LoTOx method, ozone is introduced before FGD absorber.

Another solution is to reduce pollution from flue gas with liquid oxidants. It involves their introduction into flue gas upstream of the wet or semidry flue gas desulphurization installations. Their task is to oxidize both the nitrogen oxide to NO2 and the metallic mercury to Hg2+. In the case of wet flue gas desulfurization installations, liquid oxidants may also be added to the sorption liquid tank. Hydrogen peroxide [37] is a very popular oxidant used in industry, having the valuable advantage in that it is not as harmful to the environment as chlorine compounds and, at the same time, it is relatively cheap. Exhaust gas treatment with hydrogen peroxide is an extremely promising process. Many researchers around the world are working to improve its effectiveness in relation to the oxidation of nitrogen oxides. Works are carried out

on combining the dosing of hydrogen peroxide with metal oxides [38], activating hydrogen peroxide using ultraviolet rays [39], combining H2O2 injection with catalysts (Fe-Al, Fe2O3, Fe-Ti) promoting the formation of OH\* radicals [40], and using a combination of two oxidants, e.g., H2O2/NaClO2 [41]. The results of these experiments are all very promising, and we can expect that future industrial flue gas cleaning installations will apply the presented processes. The achieved efficiency of NOx and Hg removal from the carrier gas, at least in lab scale tests, is at the level of 90% [42]. Work on the use of sodium chlorite was also carried out on a laboratory and pilot scale [43]. It achieved a removal efficiency of 99% for SO2 and Hg and 90% for NOx.

#### **4. Technologies for simultaneous removal of HgT and NOx: authors' own research**

As already mentioned, the efficiency of mercury removal in flue gas cleaning installations depends on the speciation of mercury, and the mercury present in the flue gas occurs in both the Hg0 and the Hg2+ forms. Hg2+ oxidation increases with the increase in the content of halides (chlorides, bromides, and iodides) in carbon. In the absence of a natural oxidant, as is the case with lignite, liquid oxidative additive can be used for Hg0 oxidation. Absorbers of the wet flue gas desulfurization plant capture mercury in the Hg2+ gas form. In the result of cooperation between the Wrocław University of Technology and Rafako S.A., we developed an Hg emission reduction technology dedicated for hard coal and lignite-fired units. The method involves the injection of sodium chlorite into the exhaust duct upstream the WFGD absorber. In the result of injection of the oxidant, Hg0 is oxidized to Hg2+ and NO to NO2, and these oxidation products are captured from the flue gas together with SO2 in the WFGD absorber. The technology has been tested on an industrial scale in a 400 MWe lignite-fired unit.

#### **4.1 Research on the impact of injection of oxidizer in exhaust gases on the efficiency of Hg and NOx reduction**

The tests were carried out using exhaust gases from a lignite-fired dust boiler (400 MWe) equipped with a selective non-catalytic NOx reduction installation, an electrostatic precipitator, and a wet flue gas desulfurization installation. The WFGD absorber is equipped with four levels of sprinkling and a system for feeding adipic acid into the suspension in order to increase the desulfurization efficiency. The test installation for injection of oxidizer (sodium chlorite) was built between the exhaust fan and the fan supporting the WFGD installation. The choice of the additive injection site upstream the booster fan guaranteed very good mixing of the additive with exhaust gases. The mercury content of the fuel during the tests varied between 0.215 and 0.701 mg/kg. A diagram of the installation, along with the location of the measuring points, is shown in **Figure 7** [44].

As part of the research, we performed continuous measurements of mercury concentration in exhaust gases (using two Gasmet mercury emission monitoring systems) in measuring cross sections located upstream the injection site (A) and in the chimney (C); we carried additional measurements of mercury speciation by the manual method (Ontario-Hydro) at the chimney (C), upstream the WFGD absorber (B), and upstream the oxidative additive injection site (A). Based on the continuous measurements of mercury concentration in the exhaust gas upstream of the absorber and in the chimney, the efficiency of removing mercury from the exhaust gas in the WFGD absorber was calculated with the following formula:

**77**

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

ηHg = (1 − (Hg<sup>T</sup>

NO→NO2 = (NO2

ηNOx = (1 − (NOx

moles of nitrogen oxide in the flue gas, a molar ratio X was introduced:

C/ Hg<sup>T</sup>

B/ NOx B

C/ NOx A

A is the average NOx concentration in the flue gas upstream the

To specify the number of moles of the oxidant to be applied in relation to the

Calculation of the molar ratio X was made for the concentration of NO in the flue gas measured in the chimney (C) in the period immediately prior to the oxidant injection.

is the NO2 concentration in the flue gas in the measurement cross

USR. To determine the NO to NO2 oxidation degree in a given measurement cross section, the volumetric share of NO2 in the flue gas in relation to the sum of nitric oxide and nitrogen dioxide (NOx) was determined. The NO to NO2 oxidation degree was

*Diagram of the research installation during tests on lignite flue gas. (A) Measuring cross section before oxidant injection. (B) Measuring cross section downstream the injection site. (C) Measuring cross section in the chimney.*

The effectiveness of NOx removal from the flue gas in the FGD absorber was determined based on the measurement of NOx concentration (sum of NO and NO2 calculated as NO2 [45]) in the cross section located in the chimney (C) and upstream the FGD absorber (A). The NOx removal efficiency was determined by

C is the mean total mercury concentration in the flue gas in the chim-

A is the mean total mercury concentration in the exhaust

is the NOx concentration in the flue gas in the measure-

C is the average NOx concentration in flue gas in

X = NaClO2/NO, molNaClO2/ molNO (4)

<sup>A</sup>)) · 100% (1)

) · 100,% (2)

)) · 100% (3)

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

where HgT

where NO2

USR; and HgT

ηB

B

USR; and NOx

USR.

gas upstream of the absorber (A), μg/m3

calculated by means of the relations:

B

ment cross section (B), ppm.

section (B), ppm; and NOx

means of the relation:

where NOx

absorber (A), mg/m3

the chimney (C), mg/m3

ney (C), μg/m3

**Figure 7.**

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

#### **Figure 7.**

*Environmental Emissions*

**research**

flue gas occurs in both the Hg0

tive can be used for Hg0

400 MWe lignite-fired unit.

on combining the dosing of hydrogen peroxide with metal oxides [38], activating hydrogen peroxide using ultraviolet rays [39], combining H2O2 injection with catalysts

bination of two oxidants, e.g., H2O2/NaClO2 [41]. The results of these experiments are all very promising, and we can expect that future industrial flue gas cleaning installations will apply the presented processes. The achieved efficiency of NOx and Hg removal from the carrier gas, at least in lab scale tests, is at the level of 90% [42]. Work on the use of sodium chlorite was also carried out on a laboratory and pilot scale

[43]. It achieved a removal efficiency of 99% for SO2 and Hg and 90% for NOx.

**4. Technologies for simultaneous removal of HgT and NOx: authors' own** 

As already mentioned, the efficiency of mercury removal in flue gas cleaning installations depends on the speciation of mercury, and the mercury present in the

the increase in the content of halides (chlorides, bromides, and iodides) in carbon. In the absence of a natural oxidant, as is the case with lignite, liquid oxidative addi-

plant capture mercury in the Hg2+ gas form. In the result of cooperation between the Wrocław University of Technology and Rafako S.A., we developed an Hg emission reduction technology dedicated for hard coal and lignite-fired units. The method involves the injection of sodium chlorite into the exhaust duct upstream the WFGD

NO2, and these oxidation products are captured from the flue gas together with SO2 in the WFGD absorber. The technology has been tested on an industrial scale in a

The tests were carried out using exhaust gases from a lignite-fired dust boiler (400 MWe) equipped with a selective non-catalytic NOx reduction installation, an electrostatic precipitator, and a wet flue gas desulfurization installation. The WFGD absorber is equipped with four levels of sprinkling and a system for feeding adipic acid into the suspension in order to increase the desulfurization efficiency. The test installation for injection of oxidizer (sodium chlorite) was built between the exhaust fan and the fan supporting the WFGD installation. The choice of the additive injection site upstream the booster fan guaranteed very good mixing of the additive with exhaust gases. The mercury content of the fuel during the tests varied between 0.215 and 0.701 mg/kg. A diagram of the installation, along with the loca-

As part of the research, we performed continuous measurements of mercury concentration in exhaust gases (using two Gasmet mercury emission monitoring systems) in measuring cross sections located upstream the injection site (A) and in the chimney (C); we carried additional measurements of mercury speciation by the manual method (Ontario-Hydro) at the chimney (C), upstream the WFGD absorber (B), and upstream the oxidative additive injection site (A). Based on the continuous measurements of mercury concentration in the exhaust gas upstream of the absorber and in the chimney, the efficiency of removing mercury from the exhaust gas in the WFGD absorber was calculated with the

**4.1 Research on the impact of injection of oxidizer in exhaust gases on the** 

and the Hg2+ forms. Hg2+ oxidation increases with

oxidation. Absorbers of the wet flue gas desulfurization

radicals [40], and using a com-

is oxidized to Hg2+ and NO to

(Fe-Al, Fe2O3, Fe-Ti) promoting the formation of OH\*

absorber. In the result of injection of the oxidant, Hg0

tion of the measuring points, is shown in **Figure 7** [44].

**efficiency of Hg and NOx reduction**

**76**

following formula:

*Diagram of the research installation during tests on lignite flue gas. (A) Measuring cross section before oxidant injection. (B) Measuring cross section downstream the injection site. (C) Measuring cross section in the chimney.*

$$
\eta\_{\rm Hg} = \left(\mathbf{1} - \left(\mathbf{H} \mathbf{g}^{\rm T} \rm C/Hg^{\rm T} \rm A\right)\right) \cdot \mathbf{100\%} \tag{1}
$$

where HgT C is the mean total mercury concentration in the flue gas in the chimney (C), μg/m3 USR; and HgT A is the mean total mercury concentration in the exhaust gas upstream of the absorber (A), μg/m3 USR.

To determine the NO to NO2 oxidation degree in a given measurement cross section, the volumetric share of NO2 in the flue gas in relation to the sum of nitric oxide and nitrogen dioxide (NOx) was determined. The NO to NO2 oxidation degree was calculated by means of the relations:

$$\boldsymbol{\eta}^{\rm B}|\_{\rm NO \to NO2} = \left(\rm NO\_2^{\rm B}/NO\_x^{\rm B}\right) \cdot 100,\% \tag{2}$$

where NO2 B is the NO2 concentration in the flue gas in the measurement cross section (B), ppm; and NOx B is the NOx concentration in the flue gas in the measurement cross section (B), ppm.

The effectiveness of NOx removal from the flue gas in the FGD absorber was determined based on the measurement of NOx concentration (sum of NO and NO2 calculated as NO2 [45]) in the cross section located in the chimney (C) and upstream the FGD absorber (A). The NOx removal efficiency was determined by means of the relation:

$$
\eta\_{\text{NOx}} = \left(1 - \left(\text{NO}\_{\text{x}}^{\text{C}} / \text{NO}\_{\text{x}}^{\text{A}}\right)\right) \cdot \mathbf{100\%} \tag{3}
$$

where NOx A is the average NOx concentration in the flue gas upstream the absorber (A), mg/m3 USR; and NOx C is the average NOx concentration in flue gas in the chimney (C), mg/m3 USR.

To specify the number of moles of the oxidant to be applied in relation to the moles of nitrogen oxide in the flue gas, a molar ratio X was introduced:

$$\text{XX} = \text{NaClO}\_2 / \text{NO}, \text{mol}\_{\text{NaCl}2} / \text{mol}\_{\text{NO}} \tag{4}$$

Calculation of the molar ratio X was made for the concentration of NO in the flue gas measured in the chimney (C) in the period immediately prior to the oxidant injection.

When the aqueous solution of sodium chlorite is sprayed in the flue gas upstream the absorber, first it evaporates (the temperature of the flue gas during the tests at the oxidant injection site (A) varies from 165 to 170°C) as a result of the reaction of gaseous sodium chlorite (initial pH of sodium chlorite solution was 11.5) with nitric oxide, nitrogen dioxide, and sodium chloride being formed [46]:

$$\text{NaClO}\_2\text{(l)} \rightarrow \text{NaCl}\_2\text{(g)}\tag{5}$$

$$\text{2NO}(\text{g}) + \text{NaCl}\_2(\text{g}) \rightarrow \text{2NO}\_2(\text{g}) + \text{NaCl} \tag{6}$$

Due to the significant share of moisture in the flue gas (from 28 to 29%), there were very good conditions for the formation of nitric and nitrous acids [47]:

$$2\text{NO}\_2\text{(g)} + \text{NaCl}\_2\text{(g)} \rightarrow 2\text{NO}\_2\text{(g)} + \text{NaCl} \tag{7}$$

The nitric acid formed in the flue gas reacted with the metallic mercury and oxidized it to the form Hg2+ (mercury(II) nitrate), which increases HgT removal efficiency from flue gas [43, 46]:

$$\text{Hg}^{0}\text{(g)} + \text{4HNO}\_{3}\text{(g)} \rightarrow \text{Hg}\text{(NO}\_{3}\text{)}\_{2} + 2\text{NO}\_{2}\text{(g)} + 2\text{H}\_{2}\text{O}\_{\text{(g)}}\tag{8}$$

Because flue gas contains acidic gases such as SO2, HCl, and HF, they can be absorbed by oxidant droplet and drop its pH before evaporation which caused the release of ClO2 [48]. Chlorine dioxide can directly oxidized NO and Hg0 ; additionally emission of chlorine radical is possible, which enhanced Hg0 oxidation [15, 19]:

$$\rm{SCIO}\_2^- + 4H^+ \rightarrow 4ClO\_2(g) + 2H\_2O \text{ (l)} + Cl^- \tag{9}$$

$$\text{2ClO}\_{2}(\text{g}) + \text{NO}\_{2}(\text{g}) \rightarrow \text{NO}\_{2}(\text{g}) + \text{Cl}^{\*} \tag{10}$$

$$\text{Cl}^\* + \text{Hg}^0 \to \text{HgCl} \tag{11}$$

**79**

HgT

**Figure 9.**

*the chimney (C).*

**Figure 8.**

*Oxidation NO to NO2, NOx, SO2, and HgT*

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

concentration in the chimney during the presented tests was below the level

Sodium chlorite injection into flue gas upstream of the WFGD absorber caused an increase in Hg2+ concentration in the flue gas, which translated into the efficiency of mercury removal. Unfortunately, in some cases, the increase in Hg2+ concentration in the exhaust gas intensified the phenomenon of re-emission [44].

*NO, NO2, and NOx concentrations in the flue gas downstream the injection site (B) and HgT*

The phenomenon of re-emission consists in chemical reduction of the Hg2+

**4.2 Increased Hg removal efficiency by limiting re-emissions**

USR.

 *removal efficiency in function of molar ratio X.*

mercury emitted back into the

 *concentration in* 

required by the BAT conclusions, i.e., <7 μg/m3

absorbed in the suspension to the elemental Hg0

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

$$\text{Hg}^{0}\text{ (g)} + \text{ClO}\_{2}\text{ (g)} \rightarrow \text{HgCl}\text{ (g)} + \text{O}\_{2}\text{ (g)}\tag{12}$$

In such a complicated gas mixture as flue gases from lignite combustion, the presented mechanism can occur simultaneously. For example, the efficiency of NO to NO2 oxidation and the removal of HgT and SO2 during the tests carried out in a lignite-fired power plant (sodium chlorite fed to the exhaust gas prior to the FGD absorber) are shown in **Figure 8**.

The efficiency of HgT removal and oxidation of nitrogen oxides in exhaust gases depend on the stream of injected sodium chlorite to exhaust gases, which is illustrated by the molar ratio X. Changes in total mercury concentration in exhaust gases in the chimney (C) and NO, NO2, and NOx downstream the sodium chlorite injection site (B) are illustrated in **Figure 9**. The undoubted advantage of the presented method is the almost immediate reaction of the entire system to the injected sodium chlorite. An increase in the amount of injected additive (series I < series II) causes an immediate decrease in the HgT concentration in the chimney and an increase in the NO2 concentration in the exhaust gas downstream the injection site. The

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

#### **Figure 8.**

*Environmental Emissions*

formed [46]:

efficiency from flue gas [43, 46]:

Hg<sup>0</sup>

When the aqueous solution of sodium chlorite is sprayed in the flue gas upstream the absorber, first it evaporates (the temperature of the flue gas during the tests at the oxidant injection site (A) varies from 165 to 170°C) as a result of the reaction of gaseous sodium chlorite (initial pH of sodium chlorite solution was 11.5) with nitric oxide, nitrogen dioxide, and sodium chloride being

Due to the significant share of moisture in the flue gas (from 28 to 29%), there

The nitric acid formed in the flue gas reacted with the metallic mercury and

Because flue gas contains acidic gases such as SO2, HCl, and HF, they can be absorbed by oxidant droplet and drop its pH before evaporation which caused the

were very good conditions for the formation of nitric and nitrous acids [47]:

oxidized it to the form Hg2+ (mercury(II) nitrate), which increases HgT

release of ClO2 [48]. Chlorine dioxide can directly oxidized NO and Hg0

Cl<sup>∗</sup> + Hg<sup>0</sup>

In such a complicated gas mixture as flue gases from lignite combustion, the presented mechanism can occur simultaneously. For example, the efficiency of NO

lignite-fired power plant (sodium chlorite fed to the exhaust gas prior to the FGD

depend on the stream of injected sodium chlorite to exhaust gases, which is illustrated by the molar ratio X. Changes in total mercury concentration in exhaust gases in the chimney (C) and NO, NO2, and NOx downstream the sodium chlorite injection site (B) are illustrated in **Figure 9**. The undoubted advantage of the presented method is the almost immediate reaction of the entire system to the injected sodium chlorite. An increase in the amount of injected additive (series I < series II) causes

in the NO2 concentration in the exhaust gas downstream the injection site. The

ally emission of chlorine radical is possible, which enhanced Hg0

<sup>−</sup> + 4H<sup>+</sup>

5ClO2

Hg<sup>0</sup>

to NO2 oxidation and the removal of HgT

absorber) are shown in **Figure 8**. The efficiency of HgT

an immediate decrease in the HgT

NaClO2(l) → NaClO2(g) (5)

2NO(g) + NaClO2(g) → 2NO2(g) + NaCl (6)

2NO(g) + NaClO2(g) → 2NO2(g) + NaCl (7)

(g) + 4HNO3(g) → Hg (NO3)2 + 2NO2(g) + 2H2O(g) (8)

→ 4ClO2(g) + 2H2O (l) + Cl<sup>−</sup> (9)

→ HgCl (11)

and SO2 during the tests carried out in a

2ClO2(g) + NO(g) → NO2(g) + Cl<sup>∗</sup> (10)

(g) + ClO2 (g) → HgCl (g) + O2 (g) (12)

removal and oxidation of nitrogen oxides in exhaust gases

concentration in the chimney and an increase

removal

; addition-

oxidation [15, 19]:

**78**

*Oxidation NO to NO2, NOx, SO2, and HgT removal efficiency in function of molar ratio X.*

#### **Figure 9.**

*NO, NO2, and NOx concentrations in the flue gas downstream the injection site (B) and HgT concentration in the chimney (C).*

HgT concentration in the chimney during the presented tests was below the level required by the BAT conclusions, i.e., <7 μg/m3 USR.

Sodium chlorite injection into flue gas upstream of the WFGD absorber caused an increase in Hg2+ concentration in the flue gas, which translated into the efficiency of mercury removal. Unfortunately, in some cases, the increase in Hg2+ concentration in the exhaust gas intensified the phenomenon of re-emission [44].

#### **4.2 Increased Hg removal efficiency by limiting re-emissions**

The phenomenon of re-emission consists in chemical reduction of the Hg2+ absorbed in the suspension to the elemental Hg0 mercury emitted back into the atmosphere [49]. Sulfite ions (SO3 <sup>2</sup><sup>−</sup>), acting as a reducing agent, are responsible for this phenomenon [50]:

$$\text{Hg}^{2+} + \text{SO}\_3^{2-} + \text{3H}\_2\text{O} \rightarrow \text{Hg}^0 + \text{SO}\_4^{2-} + 2\text{H}\_3\text{O}^+\tag{13}$$

$$\text{Hg}^{2+} + \text{HCOOH} + 4\text{H}\_2\text{O} \rightarrow \text{Hg}^0 + \text{HCO}\_3 + \text{3H}\_3\text{O}^+\tag{14}$$

In FGD installations, where the addition of organic acids (formic, adipic and other) serves increasing the SO2 removal efficiency, the following reaction takes place (14) [50]. Dosing organic acids increases the concentration of Ca2+, which improves the efficiency of SO2 removal from the exhaust gases. Many researchers also reported the clear effect of sulfite concentration in the suspension on Hg0 re-emission. Generally, an increase in SO3 <sup>2</sup><sup>−</sup> concentration increases the re-emission [51–53].

The re-emission phenomenon is assessed on the basis of measurements of mercury concentration in exhaust gas both upstream and downstream the WFGD absorber. In order to find out the nature of the re-emission phenomenon, research was carried out on a lignite-fired unit. We assumed that the concentration of total mercury in the cross section (C) was higher than in the cross section (B) the phenomenon of mercury re-emission from the FGD absorber was present, and the intensity of this phenomenon was described using re-emission rate:

$$\eta\_{\text{re-emission}} = \left( \left( \text{Hg}^{\text{T}} \text{g} - \text{Hg}^{\text{T}} \text{\_{B}} \right) / \text{Hg}^{\text{T}} \text{\_{B}} \right) \cdot 100\% \tag{15}$$

An example of variations in total mercury concentration in exhaust gases in the period when re-emission occurred is presented in **Figure 10**.

The observed phenomenon of mercury re-emission from the absorber lasted for approx. 4 h. Based on the analysis of the presented graphs, we calculated the degree of mercury re-emission according to Eq. (5); the calculation results are presented in **Figure 11**.

**Figure 10.** *Total mercury concentrations in flue gas upstream the WFGD absorber (B) and in the chimney (C).*

**81**

**Figure 12.**

**Figure 11.**

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

In order to explain the mechanisms of this phenomenon, the results of the re-emission degree were compared with the operating parameters of the unit and the WFGD (**Figure 12**). Mercury re-emission occurred when the absorber operating parameters changed, and the pH and ORP proved to be the most significant of them. A detailed description of the parameters affecting the intensity of the phenomenon of re-emission from the WFGD absorber is presented in the

*The degree of mercury re-emission from the WFGD absorber during measurements for a lignite-fired unit.*

*Parameters of unit and WFGD absorber operation during measurements for a lignite-fired unit.*

The observed degree of re-emission from the WFGD absorber reached 220%.

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

publication [44].

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

The observed degree of re-emission from the WFGD absorber reached 220%. In order to explain the mechanisms of this phenomenon, the results of the re-emission degree were compared with the operating parameters of the unit and the WFGD (**Figure 12**). Mercury re-emission occurred when the absorber operating parameters changed, and the pH and ORP proved to be the most significant of them. A detailed description of the parameters affecting the intensity of the phenomenon of re-emission from the WFGD absorber is presented in the publication [44].

**Figure 11.** *The degree of mercury re-emission from the WFGD absorber during measurements for a lignite-fired unit.*

**Figure 12.**

*Parameters of unit and WFGD absorber operation during measurements for a lignite-fired unit.*

*Environmental Emissions*

this phenomenon [50]:

Generally, an increase in SO3

re-emission rate:

presented in **Figure 11**.

atmosphere [49]. Sulfite ions (SO3

Hg2+ + SO3

the clear effect of sulfite concentration in the suspension on Hg0

ηre−emission = ((Hg<sup>T</sup>

period when re-emission occurred is presented in **Figure 10**.

2− + 3H2O → Hg<sup>0</sup> + SO4

In FGD installations, where the addition of organic acids (formic, adipic and other) serves increasing the SO2 removal efficiency, the following reaction takes place (14) [50]. Dosing organic acids increases the concentration of Ca2+, which improves the efficiency of SO2 removal from the exhaust gases. Many researchers also reported

The re-emission phenomenon is assessed on the basis of measurements of mercury concentration in exhaust gas both upstream and downstream the WFGD absorber. In order to find out the nature of the re-emission phenomenon, research was carried out on a lignite-fired unit. We assumed that the concentration of total mercury in the cross section (C) was higher than in the cross section (B) the phenomenon of mercury re-emission from the FGD absorber was present, and the intensity of this phenomenon was described using

<sup>C</sup> − Hg<sup>T</sup>

An example of variations in total mercury concentration in exhaust gases in the

The observed phenomenon of mercury re-emission from the absorber lasted for approx. 4 h. Based on the analysis of the presented graphs, we calculated the degree of mercury re-emission according to Eq. (5); the calculation results are

*Total mercury concentrations in flue gas upstream the WFGD absorber (B) and in the chimney (C).*

B)/ Hg<sup>T</sup>

Hg2+ + HCOOH + 4H2O → Hg<sup>0</sup> + HCO3 + 3H3 O<sup>+</sup> (14)

<sup>2</sup><sup>−</sup> concentration increases the re-emission [51–53].

<sup>2</sup><sup>−</sup>), acting as a reducing agent, are responsible for

2− + 2H3 O<sup>+</sup> (13)

re-emission.

<sup>B</sup>) · 100% (15)

**80**

**Figure 10.**

Research demonstrated that re-emission can be reduced by changing the absorber's operating parameters. We noticed that an increase in suspension temperature and pH increased re-emission, while the increase in chloride concentration in the suspension and the intensity of air flow through the suspension reduced it [54]. At the same time, numerous studies indicate that significant reductions of Hg0 re-emission can be obtained by adding various additives [53–55]. The most common are simple additions of NaHS and Na2S organic sulfides with a more complex structure. The goal is always the same, i.e., to remove from the solution (suspension) Hg2+ by formation HgS, which prevents re-emission. The effect of adding sodium sulfide (Na2S) to the suspension circulation in the WFGD absorber was studied for a lignite-fired unit, and the results are presented in **Figure 13**. 4 m3 of 10% solution of sodium sulfide were pumped directly into the tank under the absorber. In this way, the mercury concentration in the exhaust gas was reduced below the level required by the BAT conclusions (7 μg/m3 USR) for a period of approx. 4 h.

The phenomenon of mercury re-emission from the WFGD absorber is not always identifiable on the basis of measurements of total mercury concentration in exhaust gases. Hard coal tests were carried out for the WFGD absorber, purifying flue gas from two units with a capacity of 195 and 220 MWe. During the tests, both boilers operated at maximum power. Prior to the tests, measurements were performed with the Ontario-Hydro method revealing that the absorber is experiencing metallic mercury re-emission. The results of these measurements are presented in **Figure 14**.

The total mercury removal efficiency in the flue gas treatment installation (electrostatic precipitator and WFGD) was 72.4%. Mercury bound with the ash was virtually completely removed in the ESP. The flue gas downstream of the boiler contained a small amount of metallic mercury only (1.73 μg/m3 USR), which was a result of the high concentrations of halides in the fuel (Cl (0.110 ÷ 0.211%), Br (0.008 ÷ 0.011%), F (0.002 ÷ 0.004%)). The concentration of metallic mercury in the exhaust gas upstream of the absorber was lower than downstream the absorber, which meant that the absorber was the source of mercury re-emission. The total mercury removal efficiency in the ESP was 56.2% and another 36.9% in the WFGD absorber. Due to

#### **Figure 13.**

*Total mercury concentration in the chimney and upstream the WFGD absorber after a one-time injection of 4m3 of sodium sulfide (10%).*

**83**

**Figure 15.**

**Figure 14.**

of sodium sulfide was 4.3 μg/m3

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

the fact that the proportion of oxidized mercury upstream the WFGD absorber is significant, sodium sulfide was fed to the absorber to reduce mercury emissions in the flue gas in the chimney. In **Figure 15**, we present the results of measurements of mercury concentration in exhaust gas upstream and downstream the WFGD absorber, during dosing of sodium sulfide. Measurements were carried out with two

*Measurement results of mercury concentration in flue gas upstream and downstream the WFGD absorber* 

The total mercury concentration in the exhaust gas before the administration

USR, and after the addition of sodium sulfide, the

continuous emission monitoring systems and the Ontario-Hydro method.

*(continuous and Ontario-Hydro measurements) during the addition of Na2S.*

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

*Comparison of mercury concentration in flue gas for hard coal tests.*

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

#### **Figure 14.**

*Environmental Emissions*

Research demonstrated that re-emission can be reduced by changing the absorber's operating parameters. We noticed that an increase in suspension temperature and pH increased re-emission, while the increase in chloride concentration in the suspension and the intensity of air flow through the suspension reduced it [54]. At the same time, numerous studies indicate that significant reductions of Hg0 re-emission can be obtained by adding various additives [53–55]. The most common are simple additions of NaHS and Na2S organic sulfides with a more complex structure. The goal is always the same, i.e., to remove from the solution (suspension) Hg2+ by formation HgS, which prevents re-emission. The effect of adding sodium sulfide (Na2S) to the suspension circulation in the WFGD absorber was studied for

of sodium sulfide were pumped directly into the tank under the absorber. In this way, the mercury concentration in the exhaust gas was reduced below the level

The phenomenon of mercury re-emission from the WFGD absorber is not always identifiable on the basis of measurements of total mercury concentration in exhaust gases. Hard coal tests were carried out for the WFGD absorber, purifying flue gas from two units with a capacity of 195 and 220 MWe. During the tests, both boilers operated at maximum power. Prior to the tests, measurements were performed with the Ontario-Hydro method revealing that the absorber is experiencing metallic mercury re-emission. The results of these measurements are

The total mercury removal efficiency in the flue gas treatment installation (electrostatic precipitator and WFGD) was 72.4%. Mercury bound with the ash was virtually completely removed in the ESP. The flue gas downstream of the boiler contained

high concentrations of halides in the fuel (Cl (0.110 ÷ 0.211%), Br (0.008 ÷ 0.011%), F (0.002 ÷ 0.004%)). The concentration of metallic mercury in the exhaust gas upstream of the absorber was lower than downstream the absorber, which meant that the absorber was the source of mercury re-emission. The total mercury removal efficiency in the ESP was 56.2% and another 36.9% in the WFGD absorber. Due to

*Total mercury concentration in the chimney and upstream the WFGD absorber after a one-time injection of* 

USR) for a period of approx. 4 h.

USR), which was a result of the

of 10% solution

a lignite-fired unit, and the results are presented in **Figure 13**. 4 m3

required by the BAT conclusions (7 μg/m3

a small amount of metallic mercury only (1.73 μg/m3

presented in **Figure 14**.

**82**

*4m3*

**Figure 13.**

 *of sodium sulfide (10%).*

*Comparison of mercury concentration in flue gas for hard coal tests.*

#### **Figure 15.**

*Measurement results of mercury concentration in flue gas upstream and downstream the WFGD absorber (continuous and Ontario-Hydro measurements) during the addition of Na2S.*

the fact that the proportion of oxidized mercury upstream the WFGD absorber is significant, sodium sulfide was fed to the absorber to reduce mercury emissions in the flue gas in the chimney. In **Figure 15**, we present the results of measurements of mercury concentration in exhaust gas upstream and downstream the WFGD absorber, during dosing of sodium sulfide. Measurements were carried out with two continuous emission monitoring systems and the Ontario-Hydro method.

The total mercury concentration in the exhaust gas before the administration of sodium sulfide was 4.3 μg/m3 USR, and after the addition of sodium sulfide, the

concentration of total mercury in the exhaust gas dropped to 0.45 μg/m3 USR. The mercury removal efficiency for the exhaust gas in the WFGD absorber amounted to 25.5% without the addition of sulfide and increased to 90.5% after applying the additive. To sum up, due to the content of halides in coal, a considerable amount of Hg2+ is present in hard coal exhaust gas, which can be effectively removed in WFGD, as long as the phenomenon of re-emission is controlled.

#### **5. Summary**

The chapter presents selected issues related to Hg and NOx emissions from coal combustion processes, in the aspect of regulations related to limiting permissible emissions of pollutants, as contained in the BAT conclusions. The review of methods applied to reduce mercury emissions demonstrates that the specific technology should be selected individually for each facility considered. There is no single, universal, cost-effective solution. In order to choose an effective method for reducing mercury emissions, it is first and foremost necessary to hold the knowledge of the speciation of mercury in the exhaust gas downstream the boiler. In the case of low concentration of oxidized mercury, there are no devices that can be installed in order to secure sufficient limiting of mercury emissions. In such a case, one should first consider the solutions that consist in supplementing the exhaust gas with additives to oxidize the metallic mercury first.

Among the methods used for denitrification of exhaust gases, attention has been given to oxidative methods, which form an opportunity to simultaneously reduce NOx and Hg emissions. The results of the author's own research in industrial conditions confirmed the usefulness of injection of the oxidant (sodium chlorite) to the exhaust gas upstream the WFGD absorber to reduce mercury emission. Under favorable conditions for lignite flue gases, up to 70% Hg removal efficiency was achieved, coupled with 17% NOx removal efficiency and an unchanged SO2 removal efficiency. Whenever there is the phenomenon of re-emission of mercury from the WFGD absorber, appropriate measures must be undertaken to limit it. Again, test results on lignite and hard coal exhaust gas indicate that it is possible to reduce re-emissions to such an extent, as to ensure compliance with emission standards in line with BAT conclusions.

By using mercury oxidation technologies with simultaneous application of flue gas purification devices (DeNOx, DeSOx, and dedusting) and effectively combating re-emissions, we can achieve total mercury concentrations at the level required by BAT conclusions, i.e., in the order of 1–7 (4) μg/m3 USR.

**85**

**Author details**

Technology, Wrocław, Poland

provided the original work is properly cited.

Maria Jędrusik\*, Dariusz Łuszkiewicz and Arkadiusz Świerczok

\*Address all correspondence to: maria.jedrusik@pwr.edu.pl

Faculty of Mechanical and Power Engineering, Wrocław University of Science and

© 2020 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,

*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

*DOI: http://dx.doi.org/10.5772/intechopen.92342*

#### **List of abbreviations**


*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes DOI: http://dx.doi.org/10.5772/intechopen.92342*

#### **Author details**

*Environmental Emissions*

**5. Summary**

concentration of total mercury in the exhaust gas dropped to 0.45 μg/m3

WFGD, as long as the phenomenon of re-emission is controlled.

tives to oxidize the metallic mercury first.

mercury removal efficiency for the exhaust gas in the WFGD absorber amounted to 25.5% without the addition of sulfide and increased to 90.5% after applying the additive. To sum up, due to the content of halides in coal, a considerable amount of Hg2+ is present in hard coal exhaust gas, which can be effectively removed in

The chapter presents selected issues related to Hg and NOx emissions from coal combustion processes, in the aspect of regulations related to limiting permissible emissions of pollutants, as contained in the BAT conclusions. The review of methods applied to reduce mercury emissions demonstrates that the specific technology should be selected individually for each facility considered. There is no single, universal, cost-effective solution. In order to choose an effective method for reducing mercury emissions, it is first and foremost necessary to hold the knowledge of the speciation of mercury in the exhaust gas downstream the boiler. In the case of low concentration of oxidized mercury, there are no devices that can be installed in order to secure sufficient limiting of mercury emissions. In such a case, one should first consider the solutions that consist in supplementing the exhaust gas with addi-

Among the methods used for denitrification of exhaust gases, attention has been given to oxidative methods, which form an opportunity to simultaneously reduce NOx and Hg emissions. The results of the author's own research in industrial conditions confirmed the usefulness of injection of the oxidant (sodium chlorite) to the exhaust gas upstream the WFGD absorber to reduce mercury emission. Under favorable conditions for lignite flue gases, up to 70% Hg removal efficiency was achieved, coupled with 17% NOx removal efficiency and an unchanged SO2 removal efficiency. Whenever there is the phenomenon of re-emission of mercury from the WFGD absorber, appropriate measures must be undertaken to limit it. Again, test results on lignite and hard coal exhaust gas indicate that it is possible to reduce re-emissions to such an extent, as to

By using mercury oxidation technologies with simultaneous application of flue gas purification devices (DeNOx, DeSOx, and dedusting) and effectively combating re-emissions, we can achieve total mercury concentrations at the level required by

USR.

ensure compliance with emission standards in line with BAT conclusions.

BAT conclusions, i.e., in the order of 1–7 (4) μg/m3

**List of abbreviations**

APH air (pre)heater

BAT best available techniques ESP electrostatic precipitator FGD flue gas desulphurization PAC powdered activated carbon SCR selective catalytic reduction WFGD wet flue gas desulphurization USR. The

**84**

Maria Jędrusik\*, Dariusz Łuszkiewicz and Arkadiusz Świerczok Faculty of Mechanical and Power Engineering, Wrocław University of Science and Technology, Wrocław, Poland

\*Address all correspondence to: maria.jedrusik@pwr.edu.pl

© 2020 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.

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[23] Cauch B, Silcox GD, Lighty JAS, JOL W, Fry A, Senior CL. Confounding effects of aqueous-phase impinger chemistry on apparent oxidation of mercury in flue gases. Environmental Science & Technology. 2008;**42**(7):2594-2599

[24] Gostomczyk MA, Jędrusik M. Doświadczalna instalacja do redukcji emisji SO2, NOx i rtęci ze spalin kotłowych. Archiwum Energetyki. 2008;**38**(2):97-104. (in Polish)

[25] Jędrusik M, Świerczok A, Krzyżyńska R. Usuwanie rtęci w elektrofiltrach. Przemysl Chemiczny. 2014;**93**(11):1885-1888 (in Polish)

[26] Lee SJ et al. Speciation and mass distribution of mercury in a bituminous coal-fired power plant. Atmospheric Environment. 2006;**40**:2215-2224

[27] Zhang L et al. Mercury emission from six coal-fired power plants in China. Fuel Processing Technology. 2008;**89**:1033-1040

[28] US 2002/0068030A1. Method for Controlling Elemental Mercury Emission. Patent US 2002/0068030A1, June 6, 2002

[29] Knura P. Półsucha metoda odsiarczania spalin z zastosowaniem reaktora pneumatycznego zintegrowanego z filtrem tkaninowym (metoda RP + FT)—Kierunki rozwoju technologii, potencjał i możliwości. In: VI Forum dyskusyjne ENERGOPOMIAR, Tatrzańska Łomnica, 16-19 kwietnia 2013 (in Polish)

[30] Carpenter AM. Advances in Multi-Pollutant Control. IEA Clean Coal Centre; 2013. Available from: https:// www.usea.org/sites/default/files/112013\_ Advances%20in%20multi-pollutant%20 control\_ccc227.pdf

[31] Ozonek J. Analiza procesów wytwarzania ozonu dla potrzeb ochrony środowiska. Lublin: Państwowa Akademia Nauk; 2003 (in Polish)

[32] Udasin S. Firm to test out technology for purifying emissions. The Jerusalem Post. 2012. Available from: www.jpost.com/Sci-Tech/Article. aspx?id=269347

[33] Lextran. Lextran Retrofit/Upgrade Solution: Effectively Controlling the Emissions and the Expenses. Israel: Lextran; 2012. Available from: www.lextran.co.il/objects/Retrofitupgrade20-9-12.pdf

[34] Omar K. Evaluation of BOC's Lotox process for the oxidation of elemental mercury in flue gas from a coal-fired boiler. United States; 2008. DOI: 10.2172/993830

[35] Jarvis JB, Day AT, Suchak NJ. LoTOx™ process flexibility and multipollutant control capability. In: Combined Power Plant Air Pollutant Control Mega Symposium, Washington, DC, USA, 19-22 May 2003. Pittsburgh, PA, USA, Air and Waste Management Association, Paper 147. 2003

**86**

*Environmental Emissions*

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(in Polish)

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[11] Vosteen B et al. Hg-Oxidation durch Chlor, Brom und Iod in Braunkohle-Kesseln. In: 51. Kraftwerkstechnisches Kolloquium—Annual Conference of the Energy Industry and Power Plant Industry, 22-23 October 2019. Dresden: International Congress Center; 2019

[12] Oleniacz R. Oczyszczanie gazów odlotowych ze spalania odpadów niebezpiecznych. Inżynieria

[13] Lindau L, Durham M, Bustard J, Cameron M. Mercury: Myths and realities. Modern Power Systems.

[14] Available from: www.alstom.com/ mercury-emissions-technology

[15] Krotla K. Wykorzystanie systemów katalitycznego oczyszczania spalin do redukcji emisji rtęci—Podstawy teoretyczne i przykłady z praktyki. In: VI Forum dyskusyjne ENERGOPOMIAR, Tatrzańska Łomnica, 16-19 kwietnia.

[16] Nakamoto T, Kato Y, Nagai Y, Neidig K. SCR Catalyst, A Low Cost Technology for Mercury Mitigation, Hitachi Paper\_Neidig\_100213, Library: Mitsubishi Hitachi, Technical Papers

[17] Jak W. EPA, No. ICR: Information Collection Request for Electric Utility Steam Generating Unit Hg Emissions, Information Collection Effort. 1858; 1999

[18] Krzyżyńska R, Hutson ND. Effect

of solution pH on SO2, NOx, and Hg removal from simulated coal combustion flue gas in an

2003;**3**:30-32

2013 (in Polish)

Środowiska. 2000;**5**(2):85-94 (in Polish)

semanticscholar.org

[2] Wojnar K, Wisz J. Rtęć w polskiej energetyce. Energetyka. 2006;**4**:280-283

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[4] Niksa S, Fujiwara N. The impact of wet flue gas desulfurization scrubbing on mercury emissions from coal-fired power stations. Air & Waste Management Association. 2005;**55**:970-977

[5] Gale T, Lani B, Offen G. Mechanisms governing the fate of mercury in coalfired power systems. Fuel Processing

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Available Techniques (BAT) Conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for large combustion plants (notified under document C(2017) 5225)7

[9] Available from: http://www.hepaus. com/images/PDFs/hep\_FPCS\_MAPS\_

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[39] Huang XM, Ding J, Zhong Q. Catalytic decomposition of H2O2 over Fe-based catalysts for simultaneous removal of NOx and SO2. Applied Surface Science. 2015;**326**:66-72

[40] Ding J, Zhong Q, Zhang S. Catalytic efficiency of iron oxides in decomposition of H2O2 for simultaneous NOx and SO2 removal: Effect of calcination temperature. Journal of Molecular Catalysis A: Chemical. 2014;**393**:222-231

[41] Zhao Y, Hao RL, Guo Q, Feng YN. Simultaneous removal of SO2 and NO by a vaporized enhanced-Fenton reagent. Fuel Processing Technology. 2015;**137**:8-15

[42] Hao R, Zhao Y, Yuan B, Zhou S, Yang S. Establishment of a novel advanced oxidation process for economical and effective removal of SO2 and NO. Journal of Hazardous Materials. 2016;**318**:224-232

[43] Krzyżynska R, Hutson ND. The importance of the location of sodium chlorite application in a multi pollutant flue gas cleaning system. Journal of the Air and Waste Management Association. 2012;**62**(6):707-716

[44] Jędrusik M, Gostomczyk MA, Świerczok A, Łuszkiewicz D, Kobylańska M, et al. Fuel. 2019;**238**: 507-531. DOI: 10.1016/j.fuel.2018.10.131

[45] Polish Standard PN93/Z-04009/06. Air Purity Protection. Examination of the Content of Nitrogen and Its Compounds. 1993 (in Polish)

[46] Lee HK, Deshwal BR, Yoo KS. Simultaneous removal of SO2 and NO by sodium chlorite solution in wetted-wall column. Korean Journal of Chemical Engineering. 2005;**22**:208-213. DOI: 10.1007/BF02701486

[47] Sun Y, Hong X, Zhu T, Guo X, Xie D. The chemical behaviors of nitrogen dioxide absorption in sulfite solution. Applied Sciences. 2017;**7**(4):377. DOI: 10.3390/app7040377

[48] Hao R, Wang X, Liang Y, Lu Y, Cai Y, Mao X, et al. Reactivity of NaClO2 and HA-Na in air pollutants removal: Active species identification and cooperative effect revelation. Chemical Engineering Journal. 2017;**330**:1279- 1288. DOI: 10.1016/j.cej.2017.08.085

[49] Ochoa-Gonzales R et al. Control of Hg0 re-emission from gypsum slurries by means of additives in typical wet scrubber conditions. Fuel. 2013;**105**:112-118

[50] Heidel B, Hilber M, Scheffknecht G. Impact of additives for enhanced sulfur dioxide removal on re-emissions of mercury in wet flue gas desulfurization. Applied Energy. 2014;**114**:485-491

[51] Keiser B, et al. Improving Capture of Mercury Efficiency of WFGDs by Reducing Mercury Re-Emission. US8110163B2. 2012

[52] Wo J et al. Hg2+ reduction and re-emission from simulated wet flue gas desulfurization liquors. Journal of Hazardous Materials. 2009;**165**(2-3):1106-1110

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*Methods to Reduce Mercury and Nitrogen Oxides Emissions from Coal Combustion Processes*

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[53] Omine N et al. Study of elemental mercury re-emission in simulated wet

[54] Wang Y, Liu Y, et al. Experimental study on the absorption behaviors of gas phase bivalent mercury in Ca-based wet flue gas desulfurization slurry system. Journal of Hazardous Materials.

[55] Tang T, Xu J, Lu R, Wo J, Xu X. Enhanced Hg2+ removal and Hg0 re-emission control from wet flue gas desulfurization liquors with additives.

Fuel. 2010;**89**(12):3613-3617

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[53] Omine N et al. Study of elemental mercury re-emission in simulated wet scrubber. Fuel. 2012;**91**:93-101

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Solutions%208-17-12.pdf

Design. 2014;**92**:1907-1914

[39] Huang XM, Ding J, Zhong Q. Catalytic decomposition of H2O2 over Fe-based catalysts for simultaneous removal of NOx and SO2. Applied Surface Science. 2015;**326**:66-72

[40] Ding J, Zhong Q, Zhang S. Catalytic efficiency of iron oxides in decomposition

[41] Zhao Y, Hao RL, Guo Q, Feng YN. Simultaneous removal of SO2 and NO by a vaporized enhanced-Fenton reagent. Fuel Processing Technology.

[42] Hao R, Zhao Y, Yuan B, Zhou S, Yang S. Establishment of a novel advanced oxidation process for economical and effective removal of SO2 and NO. Journal of Hazardous Materials. 2016;**318**:224-232

[43] Krzyżynska R, Hutson ND. The importance of the location of sodium chlorite application in a multi pollutant flue gas cleaning system. Journal of the Air and Waste Management Association. 2012;**62**(6):707-716

2015;**137**:8-15

of H2O2 for simultaneous NOx and SO2 removal: Effect of calcination temperature. Journal of Molecular Catalysis A: Chemical. 2014;**393**:222-231

[37] Crapsey K. Eco Power Solutions Multi-Pollutant Emissions Control Systems. Northfield, IL, USA: The Mcllvaine Company; 2012. Available from: www.mcilvainecompany. com/Universal\_Power/Subscriber/ PowerDescriptionLinks/Kevin%20 Craspey%20-%20Eco%20Power%20 [44] Jędrusik M, Gostomczyk MA, Świerczok A, Łuszkiewicz D, Kobylańska M, et al. Fuel. 2019;**238**: 507-531. DOI: 10.1016/j.fuel.2018.10.131

[45] Polish Standard PN93/Z-04009/06. Air Purity Protection. Examination of the Content of Nitrogen and Its Compounds. 1993 (in Polish)

[46] Lee HK, Deshwal BR, Yoo KS. Simultaneous removal of SO2 and NO by sodium chlorite solution in wetted-wall column. Korean Journal of Chemical Engineering. 2005;**22**:208-213. DOI:

[47] Sun Y, Hong X, Zhu T, Guo X, Xie D. The chemical behaviors of nitrogen dioxide absorption in sulfite solution. Applied Sciences. 2017;**7**(4):377. DOI: 10.3390/app7040377

[48] Hao R, Wang X, Liang Y, Lu Y, Cai Y, Mao X, et al. Reactivity of NaClO2 and HA-Na in air pollutants removal: Active species identification and cooperative effect revelation. Chemical Engineering Journal. 2017;**330**:1279- 1288. DOI: 10.1016/j.cej.2017.08.085

[49] Ochoa-Gonzales R et al. Control

 re-emission from gypsum slurries by means of additives in typical wet scrubber conditions. Fuel.

[50] Heidel B, Hilber M, Scheffknecht G. Impact of additives for enhanced sulfur dioxide removal on re-emissions of mercury in wet flue gas desulfurization. Applied Energy. 2014;**114**:485-491

[51] Keiser B, et al. Improving Capture of Mercury Efficiency of WFGDs by Reducing Mercury Re-Emission.

[52] Wo J et al. Hg2+ reduction and re-emission from simulated wet flue gas desulfurization liquors. Journal of Hazardous Materials. 2009;**165**(2-3):1106-1110

of Hg0

2013;**105**:112-118

US8110163B2. 2012

10.1007/BF02701486

[38] Liu YX, Wang Q, Yin YS, Pan JF, Zhang J. Advanced oxidation removal of NO and SO2 from flue gas by using ultraviolet/H2O2/NaOH process. Chemical Engineering Research and

**88**

[54] Wang Y, Liu Y, et al. Experimental study on the absorption behaviors of gas phase bivalent mercury in Ca-based wet flue gas desulfurization slurry system. Journal of Hazardous Materials. 2010;**183**:902-907

[55] Tang T, Xu J, Lu R, Wo J, Xu X. Enhanced Hg2+ removal and Hg0 re-emission control from wet flue gas desulfurization liquors with additives. Fuel. 2010;**89**(12):3613-3617

**91**

Section 3

Composition and

Measurement of Emissions

Section 3
