OCCURRENCE OF EMERGING ORGANIC CONTAMINANTS RELEASED FROM WASTEWATER TREATMENT PLANTS IN THE AQUATIC ENVIRONMENT AND EFFECTS ON AQUATIC LIFE: THE CASE OF GREECE

摘要

Emerging organic contaminants (EOCs) are widely used compounds that have gained scientific interest during the last decade. Despite the frequent detection of these compounds in treated wastewater and surface water, there is a lack of data relevant to the hazard they exhibit to aquatic organisms.The main objective of this study was to estimate the risk associated with the occurrence of the EOCs released from municipal wastewater in the aquatic environment. For this reason Greece was chosen as a case study. Treated wastewater was analyzed for 105 pharmaceuticals and illicit drugs; whereas a literature review was held to record the concentration levels of all emerging micropollutants determined in Greek Wastewater Treatment Plants (WWTPs). An extensive literature review was also conducted in order to record the experimental acute toxicity data of these compounds (EC_(50) or LC_(50) values) for 3 different aquatic organisms (fish, daphnia magna and algae). In cases that no experimental toxicity data was available, ECOSAR model (U.S. EPA) was used. The risk quotients (RQ) were calculated for treated wastewater and 25 Greek rivers, taking into account the Measured Environmental Concentration (MEC), the Predicted No Effect Concentration (PNEC) and the dilution the wastewater undergoes when it is released in rivers. The possible risk due to the mixture of the target compounds was estimated as well, using the baseline toxicity values calculated by the ECOSAR model.According to the literature and experimental data, 207 EOCs have been detected in treated wastewater originated from Greek WWTPs, belonging to 8 different groups: pharmaceuticals, illicit drugs, phenolic endocrine disruptors (EDCs), perfluorinated compounds, benzotriazoles, benzothiazoles, artificial sweeteners and siloxanes. Their concentration levels ranged from less than 1 ng L~(-1) (pharmaceuticals) to some tens of ug L~(-1) (artificial sweeteners). EDCs seem to be the most dangerous class of the emerging pollutants, since 4 compounds (nonylphenol, nonylphenol diethoxylate, nonylphenol monoethoxylate and triclosan) presented high RQ values even after significant wastewater dilution to river water. Specifically, triclosan presented RQ > 1 (in algae) for all studied rivers (dilution factor up to 2388), while decamethylcyclopentasilane (in daphnia magna), caffeine (in algae) and nonylphenol (in fish) presented RQ values higher than 1, for 23 (dilution factor < 1910), 22 (dilution factor < 913) and 20 rivers (dilution factor < 824), respectively. The mixture of the micropollutants presents a serious hazard for aquatic organisms, as its RQ remains high (98 for fish, 123 for daphnia magna and 42 for algae), even in river with the highest dilution factor. The group of micropollutants that contribute the most in the mixture's RQ is EDCs, as its contribution came up to 99 % in fish and daphnia magna and 98 % in algae.