Because of their persistence, bioaccumulation potential, and (eco)toxicity, long-chain perfluoroalkyl substances (PFASs) are being replaced with short-chain PFASs and fluorinated alternatives. Perfluoroalkyl ether carboxylic acids (PFECAs) are one important class of fluorinated alternatives. However, almost no information exists about the occurrence of PFECAs and their behavior during drinking water treatment. The objectives of this research were determine (1) occurrence of PFECAs and traditionally studied PFASs in the Cape Fear River (CFR) watershed, which serves as a source of drinking water for ~1.5 million North Carolina residents, (2) fate of PFECAs in drinking water treatment processes, and (3) PFECA adsorbability on powdered activated carbon (PAC). In the headwater region of the CFR basin, PFECAs were not detected in the raw water of a drinking water treatment plant (DWTP), but concentrations of traditionally studied PFASs were high. The US Environmental Protection Agency’s lifetime health advisory level (70 ng/L) for perfluorooctane sulfonic acid and perfluorooctanoic acid (PFOA) was exceeded on 57 of 127 sampling days. In raw water of a DWTP downstream of a PFAS manufacturer, the mean concentration of perfluoro-2-propoxypropanoic acid (PFPrOPrA), a replacement for PFOA, was 631 ng/L (n=37). Six other PFECAs were detected with three exhibiting chromatographic peak areas up to 15 times that of PFPrOPrA. At this DWTP, PFECA removal by coagulation, ozonation, biofiltration, and disinfection was negligible. PFAS adsorbability on PAC increased with increasing chain length. Replacing one CF2 group with an ether oxygen decreased PFAS affinity for PAC, while replacement of additional CF2 groups with ether oxygens did not lead to further affinity changes.

Perfluoroalkyl ether carboxylic acids: Occurrence in the Cape Fear river watershed and fate in drinking water treatment processes

253rd National Meeting (2017)

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