Unveiling the hidden threat: spatiotemporal trends and source apportionments of per-and polyfluorinated alkyl substances in wastewater treatment plants in South Africa.

At least 11 per-and polyfluorinated alkyl substances (PFASs) were more prevalent during the dry season, whereas only PFBA, L-PFBS, L-PFOS, and PFOA were prevalent during the wet season in 11 WWTPs. The ∑ PFAS levels in the influent and the effluent ranged from 137 to 3327 ng/L and 265-7,699 ng/L in the dry season and 61-2,953 ng/L and 171-3,458 ng/L in the wet season, respectively. The highest mean concentrations were observed in the influent and effluent for PFOA (586 ng/L) and L-PFBS (552 ng/L); and FOET (1,399 ng/L) and PFNA (811 ng/L) during dry and wet seasons, respectively. During the wet season, 6:2 FTS was observed at the highest concentrations, exhibiting 4,900 ng/L (66%) and 2,351 ng/L (39%), 1,950 ng/L (53%) in SST and BNR, respectively. Principal component analysis (PCA), hierarchical clustering (HCA), and PFHpA/PFOA, PFBA/PFOA, and PFNA/PFOA ratios revealed mixtures of PFAS sources into WWTPs.