An investigation of plasma-driven decomposition of per- and polyfluoroalkyl substances (PFAS) in raw contaminated ground water

Per- and polyfluoroalkyl substances (PFAS) are contaminants of emerging concern owing to their ability to bioaccumulate in the body and subsequently cause cancer. PFAS, while recalcitrant to advanced oxidation, can be degraded by plasma action. In this work, we investigate the efficacy of two plasma reactors on degrading PFAS in ground water derived from two different contaminated sites. The reactors included an array of underwater plasma jets and a dielectric barrier discharge (DBD) with water dielectric barriers. While both reactors showed effectiveness in removing PFAS, the DBD with water barriers was most efficient with regard to the rate of degradation and power consumed. This better performance was attributed to the increased plasma–liquid contact area. Experiments indicate that air is a suitable working gas alternative to argon, and both AC and ns-pulsed power sources can generate the plasmas for these reactors. Furthermore, it was found that for both reactors, the removal rate for low and high PFAS concentration in ground water was the same, suggesting that the reactors are most efficient at treating heavily contaminated water. In this respect, a concentration step followed by plasma treatment may be a cost-effective means to treat the PFAS-contaminated water.