Separation and destruction of PFAS from groundwater using an on-site treatment train

Per- and polyfluoroalkyl substances (PFAS) are persistent and mobile contaminants that pose a considerable risk to groundwater resources. At contaminated sites, such as landfills, PFAS can migrate into groundwater, where their low sorption and high mobility facilitate plume formation and aquifer transport. Addressing this challenge requires an improved understanding of PFAS transport and effective treatment strategies. This thesis investigates PFAS behavior in groundwater systems and evaluated a field-scale integrated treatment train combining foam fractionation (FF), electrochemical oxidation (EO), and a constructed wetland (CW) for remediation of landfill leachate-impacted groundwater. The saturated paste extraction method (SPEM) was evaluated for determining PFAS solid–liquid partitioning coefficients (Kd). SPEM-derived values showed good agreement with field-based estimates and performed better than conventional batch leaching tests (L/S = 1) in low-sorption systems, confirming low Kd values and strong chain-length dependence in sandy, low organic-carbon aquifers. Full-scale FF achieved high separation of long-chain PFAS (>90%). The addition of co-foaming surfactants significantly increased short-chain separation, although separation of ≤C4 perfluoroalkyl carboxylic acids (PFCA) remained limited. The concentrated FF foamate was treated using EO, enabling substantial PFAS degradation, with high fluorine mass balance recovery indicating extensive mineralization. CW, evaluated both as a standalone and polishing step following FF, separated PFAS through substrate sorption and plant uptake, but showed limited effectiveness in reducing aqueous short-chain concentrations. Overall, the results demonstrate that combining FF and EO effectively separated and mineralized long-chain PFAS from groundwater. While co-foaming surfactants improved short-chain separation, additional polishing capable of treating ≤C4 PFCA should be considered. The limited ability of CW to reduce PFAS concentrations, however, limits its suitability for this purpose.