[Integrated Three-steps Method for Identifying Priority Pollutants in Reclaimed Water]

Trace organic contaminants （TrOCs） in reclaimed water can pose potential ecological and health risks during long-term reuse, but the current water quality standards have not restricted their limits. For preventing and controlling the potential risks from TrOCs, an integrated method EHL for identifying priority pollutants in reclaimed water was proposed. This method followed three steps： First, a meta-analysis was performed to assess the exposure of TrOCs in reclaimed water, and a database of TrOCs exposure （E） was established. Then, those hazardous pollutants of particular concern were selected from the E database based on the consensus mechanism, and a dataset of hazardous TrOCs （H） in reclaimed water was established. Finally, the risk quotient of candidates in the H dataset was calculated, and according to the risk-based prioritizing, a final list of priority TrOCs （L） in reclaimed water was recommended. To determine the procedure of EHL, the priority pollutants for reclaimed water in China were identified. Based on literature data from the past 30 years, a total of 32 TrOCs of high concern were selected. Six TrOCs with the highest risk were recommended as an executive priority list for reclaimed water management, including formaldehyde, bis（2-ethylhexyl） phthalate （DEHP）, 17β-estradiol, erythromycin, sulfamethoxazole, and ibuprofen. The EHL method could effectively identify the priority pollutants in reclaimed water and other water environments, and it is expected to play a crucial role in water quality safety evaluation and management.