Eight granular activated carbons (GAC), four anion exchange (IX) resins, and two alternative adsorbents (AAs) were tested for the removal of per-and polyfluoroalkyl substances (PFAS) from a groundwater source used for drinking water. The study was conducted using pilot(meter)-scale columns operated in continuous-flow mode for 16-26 months. Comparison between GAC adsorbents showed that bituminous GACs exhibited higher adsorption than non-/sub-bituminous GACs. Testing of a reactivated and new GAC showed no significant differences with respect to PFAS adsorption. Of the four IX resins tested, one resin showed superior adsorption when compared with all three IX resins. A surface-modified bentonite adsorbent showed superior removal efficiencies over all adsorbent types tested here. These results provide benchmark performance and adsorption capacities at pilot-scale for various adsorbents and highlight the promise of AAs to remove PFAS from water sources with low (ng/L) concentrations.

An expanding list of states have established enforceable drinking water regulations and/or advisories for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid. Additionally, many state regulations extend to shorter chain per-and polyfluoroalkyl substances (PFAS) compounds not currently addressed by the United States Environmental Protection Agency (USEPA). This current work presents batch equilibrium and continuous column (rapid small-scale column test) bench-scale experiments conducted on drinking water sources with similar PFAS composition but varying background water quality (namely dissolved organic carbon). Adsorption of PFOA was evaluated using activated carbon and an emerging modified clay as adsorbents. Both batch equilibrium and continuous column experiments demonstrated that modified clay has a greater adsorptive capacity and faster adsorption kinetics compared to activated carbon for both long-and short-chain compounds studied, as represented by PFOA and perfluorobutanesulfonic acid, respectively.

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