Per- and polyfluoroalkyl substances (PFASs) are persistent organic pollutants of emerging concern. Long-chain PFASs are being replaced by short-chain PFASs and fluorinated alternatives. For ten legacy PFASs and seven recently discovered perfluoroalkyl ether carboxylic acids (PFECAs), we investigated (1) their occurrence in the Cape Fear River (CFR) watershed of North Carolina (NC) and (2) their fate in water treatment processes. In the headwater region of the CFR basin, PFECAs were not detected in raw water of a drinking water treatment plant (DWTP), but concentrations of legacy PFASs were high. The US Environmental Protection Agency’s lifetime health advisory level (70 ng/L) for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) was exceeded on 57 of 127 sampling days. PFOS and PFOA concentrations were similar to results observed in the same area in 2006, but the speciation of perfluoroalkyl carboxylic acids shifted from longer-chain in 2006 to shorter-chain in 2013. In raw water of a DWTP downstream of a PFAS manufacturer, the mean concentration of perfluoro-2-propoxypropanoic acid, a replacement for PFOA with the trade name of GenX, was 631 ng/L (n=37). Six other PFECAs were detected with three exhibiting chromatographic peak areas up to 15 times that of GenX. At this DWTP, PFAS removal by coagulation, ozonation, biofiltration, and disinfection was negligible. At another affected DWTP, post-filter granular activated carbon adsorption led to partial removal of GenX. Our research results received attention from many stakeholders, including state regulators, local utilities, local officials, and the public. The chemical manufacturer has agreed to stop discharging GenX into the river, and state regulators have required the fluorochemical manufacturer to stop discharging additional PFASs. Current monitoring results illustrate that fluorochemical levels have decreased dramatically.

Update on occurrence and control of legacy and emerging perfluoroalkyl substances in North Carolina

255th National Meeting (2018)

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