Assessing the efficacy of the Plasma Spinning Disc Reactor (PSDR) in treating undiluted Aqueous Film Forming Foams (AFFFs).

This work used pulsed electrical discharge plasma to treat undiluted Aqueous Film Forming Foam (AFFF) solution that contained significant quantities of per- and polyfluoroalkyl substances (PFAS). The plasma was generated within a plasma spinning disc reactor (PSDR), which utilizes the electric breakdown of argon gas to create plasma over a thin liquid film generated on a spinning disc. The PSDR performance toward degradation of AFFF constituents such as fluorotelomers, perfluorinated C-C alkyl acids, and unidentified precursors was investigated. The PSDR performance sensitivity to the process parameters, such as reactor electrode design, disc rotational speed, liquid flowrate across the disc, and discharge voltage, was explored. The results indicate degradation of all quantified PFAS with chain length ≥ 4 to below detection limit within a 250 mL sample after 86 h of treatment on a 6.5 cm disc rotating at 200 rpm. The overall PSDR performance was insensitive to the tested process parameters. A direct comparison with a UV/HO process revealed the superior performance of the plasma-based treatment toward degradation of perfluorinated compounds, evidenced by higher precursor removal rates and lower energy consumption. The energy efficiency of the UV/HO system was approximately 100 times lower than that of the plasma process under all conditions. This study confirms that PSDR is a promising technology for effectively remediating PFAS in undiluted AFFF.