Quantitative and qualitative management of water resources with the use of treated wastewater in agriculture.

The principled utilization of treated wastewater can reduce the pollution load on the environment. Because on the one hand, treated wastewater can be a suitable fertilizer substitute, and on the other hand, using treated wastewater in irrigation prevents the discharge of polluted surface water into water sources. In the south of Tehran province, polluted surface water is used for irrigation in the agricultural sector, and this has led to environmental problems. To solve this problem, it has been decided to implement a plan to build surface water treatment plants and an irrigation and drainage network to transfer treated wastewater to farms. Therefore, the present study aimed to investigate the economic and environmental effects of this project in the region. A hydro-economic model has been used to achieve this goal. According to the results, in the case of the application of environmental constraints in the optimization model, the cultivation area and the farmers' profit will be reduced by about 5% and 36%, respectively, compared with the noncompliance of environmental constraints. However, this decline in profit can be compensated by adopting solutions such as improving the irrigation system, the application of treated wastewater, or using the fertilizer potential of water sources in the agricultural sector. PRACTITIONER POINTS: In the optimal economic-environmental situation, farmers' profit is reduced compared with the optimal economic situation. In the case of implementing the treated wastewater application, the farmers' profit will increase despite environmental constraints. In the optimal economic-environmental situation, fewer lands are cultivated with diverse crops than in optimal economic conditions.