Remediation of per- and polyfluoroalkyl substances in simulated groundwater combining an iron coated reactive barrier with electro-assisted regeneration

Per- and polyfluoroalkyl substances (PFAS) are persistent and mobile contaminants that are increasingly detected in groundwater. Their strong resistance to degradation and continuous release from contaminated source zones necessitate effective remediation strategies. Sorptive reactive barriers represent a promising approach for PFAS retention in groundwater. However, the accumulation of PFAS within the barrier poses challenges related to sorption capacity exhaustion and long-term material management. Therefore, sustainable strategies are needed to enhance long-term PFAS remediation performance. In the present study, a reactive barrier composed of powdered peat coated with iron oxyhydroxides (Fe-P) was evaluated for PFAS retention under conditions simulating groundwater flow. Experiments were conducted using horizontal flow-through reactors operated at different seepage velocities to represent groundwater flow across varying soil structures. At the lowest seepage velocity, the Fe-P barrier effectively retained long-chain PFAS, including perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluoroheptanesulfonic acid (PFHpS), as well as perfluorohexanesulfonamide (FHxSA), achieving retention exceeding C/C 0 = 0.3 at a bed volume of 280. Following PFAS loading, electrokinetic treatment was applied to assess the potential for the regeneration of the spent reactive barrier. Electro-assisted regeneration promoted the displacement of sorbed PFAS toward the anode, resulting in the relocation of approximately 80% of PFAS into the first 40% of the reactive barrier. The process required an energy consumption of about 2.1 kWh kg −1 , indicating its potential for scaling up for regeneration. However, PFOS and PFHxSA exhibited limited migration under the applied electrical conditions, indicating that optimized electrokinetic parameters may be required to effectively address all PFAS classes.