Presence of Per- and Polyfluoroalkyl Substances (PFAS) in Domestic Wastewater from Community Septic Systems in New Hampshire

Abstract

Domestic wastewater has the potential to contain per- and polyfluoroalkyl substances (PFAS) and may impact groundwater when discharged to on-site septic systems. This study quantified and characterized PFAS in domestic wastewater effluent discharging to leach fields from four community septic systems in New Hampshire. Median monthly PFAS concentrations in wastewater effluent (sum of 40 PFAS) ranged from 7 to 88 ng/L, corresponding to a PFAS mass loading of 3–14 μg/person/day. Perfluorocarboxylic acids constituted 70% of PFAS molar mass overall, largely attributed to perfluoropentanoic acid, perfluorohexanoic acid, and perfluorooctanoic acid. More comprehensive PFAS analysis (extended targeted list of 84 PFAS, total oxidizable precursor assay, and adsorbable organic fluorine) indicated that precursors, and potentially fluorinated pharmaceuticals, were present in domestic wastewater effluent that were unaccounted for in standard PFAS methods, especially for conventional septic systems without an innovative/alternative onsite wastewater treatment system (I/A OWTS). Where I/A OWTSs are present, microbially mediated precursor transformations may alter PFAS signals in wastewater effluent discharged to leach fields. While challenges remain in characterizing a typical domestic wastewater PFAS signature, this study demonstrates that community septic systems that aggregate wastewater from individual households can aid in understanding community-level contributions of PFAS to the environment.