An electrocoagulation and electrooxidation treatment train to remove and degrade per- and polyfluoroalkyl substances in aqueous solution

Abstract This study examined the feasibility of a novel treatment train that combines electrocoagulation (EC) with electrooxidation (EO) treatment to remove and degrade per- and polyfluoroalkyl substances (PFASs) from water. Electrocoagulation with a zinc anode could effectively remove PFASs from water, and long-chain PFASs (C7 - C10) tended to have a higher removal rate. Foam was generated when a relatively high current density (> 1 mA cm-2) was applied to a relatively high PFAS concentration (each PFAS > 0.1 μM) during EC, which promoted the separation of PFASs from the bulk solution, especially for long-chain PFASs. Isotherm-like adsorption results indicated that competitive adsorption on floc occurred between PFASs when no foam was produced in a solution containing 10 different PFASs. Acid dissolution methods could recover and concentrate 10 PFASs in controlled volumes from both the floc and the foam, and it was also successfully applied in groundwater collected from a contaminated site. The concentrated PFASs in the acid solutions were efficiently destructed using EO treatment with a Ti4O7 anode at 10 mA cm-2, and no supplement of electrolyte was needed for the floc dissolved solution. This electrochemical-based process can economically separate, concentrate and destroy PFASs in groundwater and wastewater.