Perfluoroalkyl substances in Romanian wastewater treatment plants: Transfer to surface waters, environmental and human risk assessment

Abstract

The current study aimed to determine the concentration levels of nine perfluoroalkyl substances (PFAS) in the five most significant Romanian wastewater treatment plants (WWTPs) and their transfer to natural receivers. The analytes were concentrated using a solid-phase extraction/ultrasonic-assisted extraction procedures and then selectively quantified by liquid chromatography–tandem mass spectrometry (LC–MS/MS) using electrospray ionization. In most of the wastewater samples investigated, the dominant compounds were perfluoropentanoic acid (PFPeA), perfluorooctanoic acid (PFOA), and perfluorooctansulfonate acid (PFOS), with the maximum concentration range between 105 and 316 ng/L in influents, 14.8–31.3 ng/L in effluents and removal efficiencies higher than 80 % for all selected PFAS compounds. In sewage sludge samples, PFOA and PFOS were the majority substances, with values up to 35.8 ng/g dw for PFOA and 27.8 ng/g dw for PFOS. PFOA and PFOS achieved the maximum levels by estimating mass loading and emission levels. As a result, 237 mg/day/1000 people of PFOA and 95.5 mg/day/1000 people of PFOS are entering daily in the WWTPs, while up to 31 mg/day/1000 people of PFOA and up to 13.6 mg/day/1000 people of PFOS are discharged daily into the natural emissaries. Human risk assessment shows that PFOA and PFOS are low to high risk for all age and gender categories. Children are the most exposed to PFOA and PFOS contamination in drinking water. Environmental risk assessment reveals that PFOA exhibits a low risk for some insect species, PFOS - a low risk for freshwater shrimps and a medium risk for midges, while perfluoroundecanoic acid (PFNuDA) could have a low to medium risk for midges. No assessment studies regarding the environmental and human risk of PFAS have been performed in Romania.