Risk assessment of treated urban wastewater for agricultural irrigation

The increase in the demand for resources and raw materials has led to the depletion and pollution of existing resources. The most important resource facing the danger of extinction is water. Only 2.5% of the world's water is freshwater and only 0.3% is suitable for human consumption. There are some problems that may arise when water use is not managed properly; the most important ones are water and food shortages, countries' inability to complete their economic development, health problems and migration problems. For this reason, most of the world's countries have turned to the reuse of treated wastewater for the sustainability and reuse of water. There are various uses of treated wastewater, the most important one is reuse for agricultural purposes, since 70% of the water in the world is used for agricultural irrigation, this rate is 74% in our country. Since the share of this water used for the agricultural sector in the consumption is quite large, recycling and reuse of treated wastewater seems important. The use of treated wastewater is generally evaluated according to related irrigation water quality criteria. However, impacts and risks from continuous use of treated wastewater can not be totally understood with these criteria. There are some risks in long term use of treated wastewater in agricultural irrigation with respect to the composition of wastewater. Identifying potential risks using quantitative and qualitative risk analysis methods seems necessary to prevent potential risks during implementation. In this thesis study, Samsun East Wastewater Treatment Plant (DAAT) wastewater's potential use in agricultural irrigation was evaluated using criteria defined by Wastewater Treatment Plant Technical Procedures Communiqué (Official Gazette date: 20 March 2010 and No: 27527), Draft Regulation on the Quality of Irrigation Water and Reuse of Used Water (Forest and Ministry of Water Affairs, 2015) and Food and Agriculture Organization (FAO). A different holistic evaluation and interpretation was made by applying a water quality index approach on certain wastewater parameters. Potential risks on the environment and human health were examined using the L-type and Fine-Kinney matrix methods. The risks were listed in order of importance and potential preventive measure were suggested.