**Abstract**

The ever-increasing growth of the population and the rapid development of industries are important factors that have caused an increase in water consumption and wastewater production in communities. On the other hand, in countries located in arid and semiarid regions, available water resources are limited. Therefore, the use of non-conventional water resources (sewage) in these countries is becoming more important day by day. The use of wastewater as a permanent source of water in agriculture, in addition to providing a part of water needs, also saves and sustains water resources. In this research, the effluent of the wastewater treatment plant of Arak city in the central province of Iran was studied in order to check its quality and usability in agriculture. The quality of the effluent was compared with the standards. The results of the research showed that the above wastewater has no restrictions for use in agriculture according to the investigated parameters. This text is compiled based on the results of various research studies conducted in different parts of the world. Finally, the challenges and opportunities of using wastewater in agriculture and providing suitable solutions to reduce the problems have been discussed.

**Keywords:** irrigation, sewage, sewage treatment plant, soil pollution, water quality

### **1. Introduction**

#### **1.1 What is sewage?**

Wastewater is water used for specific consumption that cannot be reused. Because this water is often impure and has an unpleasant smell, it is also called sewage.

Wastewater composition: Wastewater consists of approximately 9.99% water and other solid materials, some of which are organic materials and the other part are solid minerals dissolved or suspended in water. The bad smell of sewage is often due to organic substances in it. The source of wastewater may be domestic, industrial, agricultural, or combined. In terms of physical, chemical, biological, and polluting properties, it has four states: weak, medium, strong, and very strong. In this article, emphasis is placed on the most common type of treated wastewater, which originates from urban wastewater. This wastewater is water that contains human body waste

(excrement and urine) and wastewater resulting from sanitary measures such as bathing, washing clothes, cooking, and other kitchen uses.

Today, the problem of water shortage and environmental destruction is considered as one of the biggest problems of human societies. In the last century, due to the increase in population growth and the development of the range of human activities in different sectors, the per capita consumption of water has increased greatly. The increase in per capita consumption as well as indiscriminate use of water resources has caused the quantitative and qualitative crisis of water resources to appear in many regions of the world, especially in places that naturally face unfavorable climate and limited water resources. Effluent from urban sewage treatment plants is a great source of water that can be used in agriculture and green space. In this situation, wastewater treatment and recirculation are the most important solution in the development of water resources management, which can play an important role in water scarcity problems [1]. The use of wastewater in agriculture is common in many countries of the world, including the United States of America, Canada, France, Germany, Mexico, Brazil, Egypt, Morocco, Jordan, Saudi Arabia, Qatar, China, etc. [2–8]. In the country of Iran, in recent years, due to the limitation of water resources, population growth, development of urbanization, industries, and agriculture, as well as the development and implementation of numerous plans for the collection and treatment of wastewater, the use of wastewater in agricultural lands has become particularly important and is in the priorities of the program. A study was conducted to identify the state of sewage treatment and the quality of production effluents in Kish Island. The results of this study showed that the quality of wastewater in Kish Island was consistent with the reuse standards of the Environmental Protection Organization for irrigation in all parameters except the total number of coliforms and fecal coliforms. Compared to the standards of the World Health Organization, the said effluent is suitable for drip irrigation and tree irrigation, and it was not found suitable for watering sports fields and green spaces of hotels. Amjad et al. (2006) by examining the facilities and capabilities of reusing urban wastewater in Yazd showed that the quality of the wastewater compared to the standards of the Environmental Protection Organization for reuse in agriculture and irrigation is suitable for irrigation and agriculture [9]. Alaton et al. (2007) studied the effluents of four selected refineries in Turkey and showed that the results are appropriate in terms of common control parameters and heavy metal concentrations. However, the wastewater of selected treatment plants has not been satisfactory in terms of microbes, especially fecal coliforms [1]. Hong Yong and Abbaspour (2007) analyzed the potential of reuse in Beijing city by applying linear programming model. The results of this study evaluated the effective and key factors of reuse potential and provided the basic foundations of this evaluation in other Chinese cities as well [10]. Almas et al. (2006) investigated the performance of sewage stabilization ponds (WSP) in Aden city with experiments on effluents and showed that it is possible to use effluents for limited irrigation [11]. Due to the differences in climatic, plant, social, cultural conditions, soil quality, and the variability of wastewater characteristics from one region to another and even over time in one place, it is wrong to only rely on the application of the instructions provided in other regions of the world, and in the long term, it causes irreparable damage to soil and water resources [12]. Although the use of wastewater in the agricultural sector has many advantages, it is because such waters contain substances such as salts, sodium, chlorine, boron, pathogenic microorganisms, and in some cases, heavy metals or organic and inorganic compounds. Another disadvantage is that their unplanned use

#### *Investigating Issues and Problems of Using Sewage Effluent in Agriculture DOI: http://dx.doi.org/10.5772/intechopen.108636*

can cause very adverse environmental consequences, many of which will not be possible to compensate for, at least in the short term. Salinization of soils, destruction of soil structure, poisoning of plants, and reduction of their performance, pollution of surface and underground water sources, and spread of diseases are prominent examples of these effects. For this reason, in order to prevent short-term and long-term adverse effects of wastewater use, special plans and provisions should be considered. In this article, mainly the challenges associated with the application of wastewater in agriculture are examined and the points that are necessary to be followed in the planning and management of wastewater application plans are discussed, and not paying attention to them will prevent the achievement of the goals of the sustainable development program of agriculture. It creates ambiguity. The general purpose of reuse of wastewater in agriculture is to optimize and preserve the availability of water resources by returning the wastewater flows to the ground and rational use of freshwater resources. Experience has shown that the presence of significant amounts of substances such as phosphate, potassium, and nitrogen in wastewater, which all play a valuable role in the fertility of agricultural land, has been effective in increasing the amount of crops. On the other hand, due to the provision of water for agriculture, new lands can be cultivated, and this will play a key role in controlling the migration of villagers to cities.

## **2. Location of the area**

The location of Iran in a dry and semiarid climate and severe pressures on renewable water sources as a result of recent droughts and the increasing development of urbanization, today the optimal use of available non-conventional water such as urban sewage and Home has been taken into consideration. The reuse of wastewater in the study area of this research is considered important in order to meet the increasing needs of water. At the time of conducting this research, the effluent of Arak sewage treatment plant was randomly used by downstream farmers after being discharged to Mighan desert. Therefore, in order to prevent threats to public health, soil contamination, the entry of pollutants into water sources, and the contamination of agricultural products, it is necessary to reuse it consciously and with the necessary investigation along with the quality control of the effluent at the source. In this research, the wastewater treatment plant of Arak city was studied in order to check its quality and usability in agriculture. The present research is cross-sectional descriptive and sampling of wastewater and conducting tests to determine the quality of wastewater and compare it with the standards.

Arak is one of the cities of Central Province in Iran. The study area of North Arak is an agricultural pole. The water used and needed by different departments is provided exclusively from underground water. Therefore, the limitation of water resources in agriculture and the increasing need for water in the industrial sector have become the concern of the provincial officials. Arak sewage treatment plant is located 10 kilometers north-east of the city (**Figure 1**). This treatment plant with the capacity to treat the wastewater of 105,000 people and receiving wastewater from a number of industries has about 75,000 cubic meters of treated wastewater per day, which is released into the environment and finally flows into the Meghan desert lake. Many lands in the villages around the refinery are barren, and cultivating them can be an effective help in creating employment.

**Figure 1.** *The location of Markazi Province in Iran.*
