Application of Rapid Small-Scale Column Tests for Treatment of Perfluoroalkyl Acids Using Anion-Exchange Resins and Granular Activated Carbon in Groundwater with Elevated Organic Carbon
Charles E. Schaefer, Dung Nguyen, Veronika Culina, Jennifer L. Guelfo, Naveen Kumar
Abstract
Rapid small-scale column tests (RSSCTs) are often employed in laboratory testing to determine contaminant treatment effectiveness by anion-exchange resins (AERs) or granular activated carbons (GACs) in a short timeframe compared to pilot testing. RSSCTs are performed by reducing the AER or GAC particle size via grinding, allowing for increased mass transfer and water throughput. However, the scaling factors between ground and unground resins for perfluoroalkyl acids (PFAAs), specifically for waters with elevated natural organic carbon levels, remain uncertain. Bench-scale column experiments were performed to evaluate the applicability of employing RSSCTs for removal of PFAAs from groundwater with elevated naturally occurring organic carbon using ground and unground AERs and GACs. For both the AERs and the GAC, PFAA migration through the columns was well-described by the Thomas model. A constant diffusivity model was appropriate for describing transport. For GAC and one of the AERs tested, the inclusion of near-surface adsorption was accounted for by scaling the equilibrium sorption capacity to r–0.5.