Occurrence and Ecotoxicological Risk Assessment of Emerging Contaminants in Urban Wastewater Treatment Plant

Abstract

This is the first study of a broad range of chemical classes of emerging contaminants conducted by analyzing influent and effluent samples from the wastewater treatment plant of the city Topola, in Serbia. The list of compounds is extensive and this paper provides a better understanding of the environmental burden from different classes of emerging contaminants. The samples were prepared using an optimized solid-phase extraction method and analyzed by liquid chromatography-tandem mass spectrometry. Removal patterns of selected compounds are discussed based on their physico-chemical properties and detected concentrations. Significant removal efficiencies, exceeding 70%, were found for the majority of investigated pharmaceuticals, pesticides, steroids, and sweeteners. Ecotoxicological risk assessment was performed by using two complementary methods: (1) an individual substance approach, based on the calculation of risk quotients (RQs) for each substance as the ratio of Predicted Environmental Concentration (PEC) and Predicted No Effect Concentration (PNEC), and (2) mixture risk assessment ("the cocktail effect") based on the summation of individual RQs. The classical approach (ERA method with individual substances) identified amlodipine as the riskiest substance in WWTP effluent. The mixture ERA approach revealed new risks, which were not recognized by the classical ERA method, indicating that individually "safe" emerging compounds can contribute to a significant risk of the whole effluents.