Treatment of PFAS-laden solids via fluidized bed gliding arc plasmatron

The extensive use and recalcitrance of per- and polyfluoroalkyl substances (PFAS) have caused soil and water contamination across the globe. Most PFAS destruction technologies are applied to aqueous matrices; there is a need for technologies that can effectively treat PFAS-contaminated solids. In this study, a fluidized bed gliding arc (non-thermal) plasma reactor (FB-GAP) was used to treat PFAS-laden sand under different gas discharges. Argon plasma did not degrade PFAS, suggesting there is no dissociative electron attachment in dry gas. Similar parent compound degradation and defluorination extents were observed under air- and nitrogen-discharges, implying that thermolysis was the main PFAS degradation process. The use of methane as an auxiliary gas increased maximum temperatures and reduced treatment costs through plasma-assisted combustion of a lean fuel mix. The fluorine mass balance was ∼20 % after accounting for fluoride and targeted PFAS in treated solids and aqueous base traps for the effluent gas. The difference (∼80 %) likely resulted from irreversible reactions with SiO₂ or formation of volatile organofluorine compounds. Further treatment of the effluent gas through the plasmatron is proposed as an alternative to fully mineralize PFAS. The results from this study demonstrate that non-equilibrium plasma technologies are a promising treatment option for PFAS-laden solids.