Performance of StyDex Beads for Removal of PFAS and Pharmaceuticals at a Municipal Wastewater Treatment Plant

Abstract We evaluated the performance of a new styrene-functionalized β-cyclodextrin (StyDex) bead formulation for removing a mixture of per- and polyfluoroalkyl substances (PFAS) and pharmaceuticals from municipal wastewater effluent using rapid small-scale column tests (RSSCTs) and a four month pilot study at a municipal wastewater treatment plant (WWTP). RSSCTs at five contact times (CTs) guided pilot operation using larger StyDex beads at CTs of 2.4, 3.3, and 4.2 min. StyDex beads successfully removed PFOA, PFHxA, PFHxS, bezafibrate (BEZ), and diclofenac (DCF) but showed limited removal of PFBA. Competitive sorption favored higher-affinity contaminants (PFOA, PFHxS, and DCF) at the longest CT (4.2 min), while lower-affinity contaminants (PFHxA, PFBA, and BEZ) were best removed at 3.3 min. Mass balance indicated that StyDex beads reached sorption capacity after ∼60k bed volumes (BV) during the pilot study. Columns were successfully regenerated, with 97% of sorbed contaminants desorbed in the first 135 BV and complete desorption after 231 BV. The constant diffusivity (CD) model reliably captured pilot breakthrough behavior, consistent with intraparticle diffusion as the rate-limiting step for contaminant uptake. Overall, StyDex beads achieved sustained removal of PFAS and pharmaceuticals from municipal wastewater over four months and were effectively regenerated, demonstrating their potential for long-term wastewater treatment.