Epsilon Archive for Student Projects

Abstract

Worldwide use of per- and polyfluoroalkyl substances (PFASs), both legacy and past, are problematic due to their persistent nature. To date, PFASs are of high concern since they have been found not only in the environment but also in animals, plants and humans. Therefore, the Swedish Food Agency has set a limit of 90 ng/L for ∑11PFASs in drinking water. This study has assessed 47 drinking water plants (DWTP) in Sweden, where both in- and outgoing water was analyzed for 26 different PFASs during two different seasons (mid summer and late fall). The aim of this study was to assess the PFAS concentrations, removal efficiencies in DWTPs and seasonal trends. The maximum ∑26PFAS concentrations were close or slightly over the limit of 90 ng/L in raw water at a few DWTPs during both seasons but the drinking water concentrations from both seasons were well below 90 ng/L. Most detected PFASs were included in the Swedish drinking water guidelines, except for FOSA. In early summer, the dominant PFASs in drinking water were PFOA (74%), FOSA (74%), PFHxS (48%), PFNA (48%) and PFBS (24%), while in the fall the dominant PFASs were that 6:2 FTSA (62%), FOSA (48%), PFBS (33%), PFHxS (31%) and PFOA (26%). Removal efficiencies showed efficient removal in the early summer for PFOA, PFBS, PFHxS, PFOS, and in fall the highest removal was observed for PFPeA, PFHpA, PFNA, PFBS, PFHxS, PFOS, 6:2 FTSA and FOSA, although the variations between the individual DWTPs was high. DWTPs which used granulated activated carbon (GAC) showed high removal of PFOA, PFNA and PFHxS in early summer and PFOA, PFNA, PFHxS and 6:2 FTSA in fall. Branched PFOS and PFHxS was detected only at a few DWTPs. Allthough the PFAS concentrations were slightly higher in early summer, there were no significant difference in the PFAS concentrations in raw water between summer and fall (Wilcoxon paired rank test, p = 0.15). Overall, the concentrations of PFAS at the investigated DWTPs were below the Swedish drinking water guidelines.