Economic and Environmental Effects of Treated Wastewater Use in Agriculture in the South of Tehran City with SWAT model

The location of Tehran as the largest consumer of urban water in the country and also the different uses of water in this city, has led to the flow a significant volume of surface water resources in streams and canals in the southern regions of Tehran. These polluted surface runoffs are currently used in combination with underground water sources in agriculture in south of Tehran, which has adverse environmental consequences. The Surface water organization project in the south of Tehran in the Regional Water Company of Tehran has been explored to tackle the problem. Hence in this study, the economic and environmental effects of treated wastewater use in agriculture in the South of Tehran have been surveied in terms of project implementation and comparing the results with existing conditions in the region that uses polluted water for agricultural lands irrigation. According to the results, if the plan is implemented, the average amount of runoff has decreased from 201 to 84 cubic meters per hectare, and the amount of nitrates in the runoff has decreased from 14 to 0.1 kg per hectare. Also, by entering the wastewater into the plan area and using the fertilizer potential of the wastewater, the amount of nitrogen fertilizer consumption can be reduced by 5039 tons, which will reduce the costs of the farmers in the area by 55431 million Rials. As a result, the implementing the Surface water organization project in the south of Tehran will bring positive environmental effects.