Is combination of UVC and H2O2 effective to remove estrogens from water?

International audienceWater pollution is of major concern in France. Half of water resources was still not meeting the European quality requirement in 2012. Moreover, recent progresses in analytical chemistry have identified numerous micropollutants in Wastewater Treatment Plant (WTP) discharge coming from urban, agricultural or industrial activities. Amongst hundreds of micropollutants, estrogenic compounds were shown to cause endocrine disruption in fish at very low doses [3] and suspected to impact human fertility [4]. Therefore, WTP upgrade is needed to eliminate these endocrine disruptors. Advanced oxidation processes were shown to eliminate up to 80% of targeted micropollutants [6]. However small and middle sized WTP (< 10000 equivalent inhabitants) are poorly equipped despite representing 90% of the overall French WTP [7]. Advanced Oxidation Processes (AOPs), based on the generation of highly reactive hydroxyl radicals for the unselective oxidation of chemical pollutants can be an adequate solution. This study aims at developing a cost-effective UV/H₂O₂ advance oxidation process (AOP) in order to reduce estrogenic activity in small and middle sized WTP discharge. Experiments were conducted at 20°C with a commercial UV reactor (COMAP WT) and a 55W low pressure lamp (Phillips) emitting at 254nm. Local tap water (Lyon, France) was added in a 50L glass tank and circulated at a flow rate of 40L/min in a closed system. A mixture of Estrone (E1), β-Estradiol (E2), and α-ethynyl estradiol (EE2) was added at 5µM and degradation rates were measured during either UV (photolysis) or UV + H₂O₂ treatments over 60min. Samples were taken every 10 minutes and analyzed by HPLC. Three different concentrations of H₂O₂ were tested: 10, 50 or 100mg/L. First results showed a low degradation of E2 and EE2 by photolysis after 60 min exposure (< 20%) in tap water but E1 was well degraded (up to 80%). When adding H₂O₂, every hormones degradation rate were significantly improved. Degradation rate reached 80% for E1 and 90% for E2 and EE2 at 10mg/L H₂0₂. Total degradation was both reached with 50mg/L and 100mg/L H₂0₂. These results pointed out that estrogens removal can be highly enhanced by combining UV and H₂O₂. Further investigations are needed to test this process on treated water at environmental concentrations