Study on the safety of recycled water irrigation in arid, semiarid and underdeveloped areas: a case study in Qinghai Province

Sewage recycling is an important initiative for alleviating the gap between water supply and demand in arid areas, promoting water conservation and reducing discharge, and it is also a key factor in promoting the sustainable development of human society. Irrigation is the main route for recycled water use; however, the safety of recycled water for irrigation has been a concern for experts and policy-makers, and further research is needed to ensure the safety of recycled water for irrigation. As an example, a study on the safety of recycled water sources in arid, semiarid and underdeveloped areas was conducted in Qinghai Province, China. Based on fieldwork and monitoring data collected from 30 sewage treatment plants by a third party in Qinghai Province and a comparison of relevant standards and regulations on sewage discharge and recycled water use, similarities and differences in water quality indices were identified. Indices of common concern and discrepancy indices were analyzed for different levels of compliance based on different standards to assess whether the quality of effluent from sewage treatment plants meets the standard requirements for recycled water irrigation. The results showed that the quality of sewage treatment plant effluent in Qinghai Province was very high, achieving much higher than the national requirement of 80% standard compliance, and that the effluent quality was stable and safe, fully meeting the requirements for recycled water irrigation. This study highlights the safety of recycled water sources in arid, semiarid and underdeveloped areas and lays the foundation for the intensive development of recycled water irrigation in these areas.