Discharge of Per- and Polyfluoroalkyl Substances in Reclaimed Wastewater: Temporal Water Quality Implications for Effluent-Dominated Systems

Abstract

Because effluent-dominated and dependent systems may reflect exceedance of an earth system boundary for per- and polyfluoroalkyl substances (PFAS), we examined municipal effluents over 2 years from two semiarid cities of similar size that contribute to downstream de facto water reuse. We also quantitated sucralose as an effluent tracer but did not observe a significant relationship with sum PFAS as previously reported at the watershed scale. Sum PFAS significantly (p < 0.05) differed between study years (126 vs 85 ng/L), but did not significantly differ among seasons between discharges, although significant (p < 0.05) differences among seasons were observed for sum of long-chain PFAS and sum of precursor PFAS in effluents A and B, respectively. We identified that perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) levels did not exceed recent water quality criteria for aquatic life on any sampling event. Using recent finished drinking water values, we observed PFOS and PFOA concentrations to exceed a potable water limit (4 ng/L) for most effluent samples. However, no effluent samples exceeded World Health Organization drinking water levels for these contaminants. These results identify the need for further understanding PFAS environmental introduction concentrations and exposure scenarios when instream dilution is limited and earth system boundaries may be exceeded.