Electrochemical Mineralization of Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) are fluorinated organic compounds with broad applications in aqueous film-forming foams (AFFF) for firefighting, lubricants, waterproof and stain-resistant products. Perfluorooctanoic acid (PFOA), a legacy PFAS, is toxic and carcinogenic. Currently, PFOA is replaced by the ammonium salt of a perfluoroalkyl ether carboxylic acid known as GenX. Nevertheless, PFOA is expected to be present in the environment for an extended period after its phasing out due to its recalcitrant nature. In addition, GenX is predicted to have similar toxicity as PFOA. Various PFAS, including PFOA and GenX, have been widely detected in surface water and groundwater in the United States and worldwide. The current treatment practice for PFAS fails to provide a permanent solution and is likely to increase the risk of recontamination of surface water and groundwater.
Among various destructive methods, electrochemical mineralization, which uses electric power to transform PFAS into bicarbonate and fluoride, is a promising option. However, past studies on electrochemical mineralization of PFAS have limitations such as low PFAS mineralization and incomplete fluorine mass balance. Hence, this study proposes a sequential treatment with ion exchange to capture and concentrate PFAS in surface water and groundwater into a low volume of brine, followed by electrochemical treatment of the PFAS-containing brine. This study will focus on the electrochemical oxidation part of the treatment train and examine the treatment performance using PFOA, GenX, and AFFF waste streams as examples.