Non-target screening and laboratory experiments reveal the transformation products and negligible trifluoroacetic acid formation potential of PFAS pesticides and pharmaceuticals in wastewater treatment plants

• PFAS pesticides and pharmaceuticals (PPs) were the dominant PFAS in WWTPs. • Fipronil’s negative removal is attributed to reconversion of human metabolites. • Seven transformation products (TPs) of PFAS PPs were identified for the first time • PFAS PPs could form trifluoroacetic acid during total oxidation precursor assays. • PFAS PPs are unlikely to be biodegraded into trifluoroacetic acid in real WWTPs. The increasing use of fluorinated pesticides and pharmaceuticals has raised global concerns. Among them, substances containing –CF 3 group are referred to as PFAS pesticides and pharmaceuticals (PFAS PPs) in this study and exhibit higher bioaccumulation and persistence. Moreover, their transformation products (TPs) may enhance their hazards. In this study, actual field monitoring and laboratory simulation experiments were conducted to reveal the occurrence, removal, risk, and trifluoroacetic acid (TFA) formation potential of PFAS PPs and TPs in wastewater treatment plants (WWTPs). Five PFAS PPs and twelve TPs were identified in wastewater, among which 7 TPs were detected for the first time in the environment. PFAS pharmaceuticals showed the highest average concentrations (127 ng/L) among 33 classes of PFAS detected in influent. Average removal rates of 17 PFAS PPs and TPs ranged from −76.6% to 81.5%. Activated sludge assays revealed that the negative removal of PFAS PPs was attributed to reconversion of their human metabolites. TPs of PFAS pesticides and PFAS pharmaceuticals exhibited higher bioaccumulation and mobility, respectively. TFA molar yields of the seven PFAS PPs and TPs ranged from 4.7% to 19.8% in the total oxidation precursor assays. However, no TFA formation was observed after biodegradation of the seven PFAS PPs and TPs by activated sludge simulating real conditions, indicating that they are unlikely to be transformed into TFA in real WWTPs. These results reveal the significance of unconventional PFAS PPs and TPs for overall PFAS in wastewater, highlighting the need to move beyond conventional PFAS toward the fast-growing PFAS PPs.