Wide-scope target analysis of emerging contaminants in landfill leachates and risk assessment using Risk Quotient methodology

[Display omitted] •58 emerging contaminants were detected in raw and treated landfill leachates.•Pharmaceuticals, industrial chemicals, and plant protection products were mainly found.•The number of compounds and their concentrations were reduced during treatment.•Possible threat from the occurrence of several compounds even in treated leachates.•2-OH-BTH and bisphenol A seem to pose the highest risk. Raw and treated leachate samples were collected from different landfills in Greece and analyzed for several groups of emerging contaminants using high resolution mass spectrometric workflows to investigate the possible threat from their discharge to the aquatic environment. Fifty-eight compounds were detected; 2−OH-benzothiazole was found at 84 % of the samples and perfluorooctanoic acid at 68 %. Bisphenol A, valsartan and 2−OH-benzothiazole had the highest average concentrations in raw leachates, after biological treatment and after reverse osmosis, respectively. In untreated leachates, Risk Quotients > 1 were calculated for 35 and 18 compounds when maximum and average concentrations were used, indicating an ecological threat for the aquatic environment. Leachates’ biological treatment partially removed COD and NH4+-N, as well as 52.3 % of total emerging contaminants. The application of reverse osmosis resulted in a 98 % removal of major pollutants, 99 % removal of total emerging contaminants and a significant decrease of ecotoxicity to Lemna minor. Beside the decrease of the detected micropollutants during treatment, RQs > 1 were still calculated for 13 and 3 compounds after biological treatment and reverse osmosis, respectively. Among these, special attention should be given to 2−OH-benzothiazole and bisphenol A that had RQ values much higher than 1 for all tested organisms.