Comparing PFAS removal across multiple groundwaters for eight GACs and alternative adsorbent

Eight granular activated carbons (GACs) and one alternative adsorbent (AA) were evaluated using rapid small-scale column tests (RSSCTs) to remove low level per- and polyfluoroalkyl substances (PFAS) from several groundwaters. Results suggested variability among waters for adsorbents to reach breakthrough. Time to reach breakthrough appeared to be inversely proportional to the background dissolved organic carbon (DOC). Bituminous GACs (particularly F400 and UC1240LD) were more effective than non-bituminous. The elution order for PFAS was PFHxA (C6) > PFBS (C4) > PFOA (C8) > PFHxS (C6) > PFOS (C8). Multivariate regression predicted bed volumes at which F400 reached significant exhaustion (defined here as 60%) for PFOA using only two parameters (humic acid, DOC). This merits further study as these parameters could potentially be incorporated into models for predicting PFAS breakthrough. VOCs presence negatively impacted PFAS adsorption on GAC. Relative to GACs, the AA was not nearly as impacted by DOC and showed superior performance.