Hydrodynamic Intensification of PFAS Adsorption: Comparative Evaluation of Rotating Bed Reactor, Batch, and Column Systems Using Granular Activated Carbon and Ion Exchange Resin

Despite advances in reactor-based process intensification, the influence of hydrodynamic conditions on PFAS removal remains poorly understood. In particular, rotating bed reactors (RBRs), which are designed to enhance mass transfer, have not been systematically evaluated for PFAS removal or compared with conventional batch and fixed-bed column systems. This lack of comparative understanding limits the ability to assess their practical relevance for PFAS remediation. In this study, PFAS removal was investigated under intensified hydrodynamic conditions using an RBR and compared with batch and small-scale column systems with special focus on short-chain PFAS compounds. The RBR significantly enhanced adsorption kinetics, with pseudo-first-order rate constants increasing by 3 to 16-fold across PFAS, particularly for short-chain PFAS. For instance, PFBA exhibited near-complete removal within 12 h in the RBR, whereas only ~50% removal was achieved in batch conditions. However, faster kinetics did not translate into superior long-term breakthrough performance compared to the column treatment system. After 50 treatment cycles using ion exchange resin, PFBA reached approximately 40% C/C0 in the RBR, while the column system maintained C/C0 below 5%; similar trends were observed for PFPeA (15% vs. ~0.5%) and PFHxA (6.2% vs. ~0.2%). These findings reveal a fundamental trade-off between kinetic intensification and long-term treatment performance. The results highlight distinct design roles, with RBR systems enabling rapid and intensified treatment (e.g., staged or parallel configurations), while conventional column systems perform better for continuous operation and compliance control in PFAS remediation.