Role of wastewater treatment plant (WWTP) in environmental cycling of poly- and perfluoroalkyl (PFAS) compounds

The role of wastewater treatment plant (WWTP) in environmental cycling of the poly- and perfluoroalkyl compounds (PFASs) through the aqueous effluent, sludge and air emission has been critically reviewed here. Understanding the role WWTPs can provide better understanding of global cycling of persistent PFASs and assist in formulating relevant environmental policies. The review suggested that, the WWTP effluent is a major source of perfluoroalkyl acids (PFAAs) in surface water. Land application of biosolids (treated sludge) have shown preferential bioaccumulation of short chain (<C7) PFAAs in various plant compartment, leading to possible contamination of the food cycle. Elevated air concentration (1.5 to 15 times) of ?PFASs were reported higher on WWTP sites (above aeration tanks), compared to reference sites not contaminated with WWTP emission. The air emission of neutral PFASs has important implication considering the long-range transport and subsequent degradation of the neutral compounds leading to the occurrence of recalcitrant PFAAs in pristine, remote environments. Research gap exist in terms of fate of polyfluroalkyl compounds (neutral PFASs) during wastetwater treatment and in aquatic and terrestrial environemnt. Considering the wide range of commercially available PFASs, measuring only perfluorocarboxylic acid (PFCA) and perfluorosulfonic acid (PFSA) can lead to underestimation total PFAS load derived from WWTPs. Knowledge of the various pathways of PFAS from WWTP to receiving environment, outlined in this study can help to adopt best possible management practices to reduce the release of PFASs from WWTP.