Removal of 48 per- and polyfluoroalkyl substances (PFAS) throughout processes in domestic and general industrial wastewater treatment plants: Implications for emerging alternatives risk control.

Wastewater acts as a significant sink and source of per- and polyfluoroalkyl substances (PFAS). This study investigated the occurrence, removal and mass flow of 48 emerging and legacy PFAS in 8 domestic and general industrial wastewater treatment plants (WWTPs) throughout entire treatment processes. In wastewater and sludge, 24 and 26 PFAS were detected, with concentrations of 246-27,100 ng/L and 91.6-214 ng/g, respectively. Predominant substances included 2H,2H-perfluorooctanoic acid (6:2 FTCA), 2H,2H-perfluorododecanoic acid (10:2 FTCA), and perfluorooctanoic acid (PFOA). Novel alternatives such as hexafluoropropylene oxide dimer acid (GenX) were not detected. Removal efficiency of total PFAS was 1-46 % in domestic WWTPs but negative in industrial WWTPs, with one industrial WWTP showing a 27-fold increase due to 6:2 FTCA generation. Median removal efficiency revealed that 9 out of 13 major PFAS decreased after treatment, while 4 increased. PFAS with -CH- group showed weaker sludge sorption compared to those with perfluorinated carbon chains. Mass flow analysis revealed wastewater is the major fate rather than sludge for emerging PFAS. Increased mass flows of fluorotelomer carboxylic acids (FTCAs) and perfluorobutanesulfonic acid (PFBS) were observed at biochemical treatment and disinfection. The ecological risk assessment using a relative risk ranking model identified higher risks from PFBS, polyfluoroalkyl phosphate mono-esters, and FTCAs. Emerging PFAS pose challenges in removal and greater hazards to ecosystems, necessitating careful evaluation and restriction to address their risk.