Field Demonstration of PFAS Destruction in Various Alcohol-Resistant AFFFs Using Supercritical Water Oxidation (SCWO)

Aqueous film-forming foams (AFFFs) have been used for over 60 years to control dangerous Class B fires, but their firefighting efficacy is owed to per- and poly fluoroalkyl substances (PFAS), which have emerged as concerning persistent contaminants for the environment and human health. Battelle’s PFAS Annihilator, a supercritical water oxidation (SCWO) technology, demonstrated ≥3 log destruction of PFAS in each of the three alcohol-resistant AFFF formulations from different manufacturers. A comparison between dilutions (6–16%) ranging from 1.9 to 64 ppm PFAS similarly demonstrated >99.9% destruction for all AFFF dilutions. Minimal reactor corrosion is indicated based on the reactor metals’ concentrations measured in the effluent, amounting to just 0.0004% (∼83 mg) wall loss per hour of operation. A similar approach estimates the formation of ∼3.1 g of precipitated salts in the reactor per hour of operation. A fluorine mass balance yielded 40% excess fluorine in the effluent compared to the influent, indicating a lot of unquantifiable nontarget PFAS precursors in the AFFF formulations. SCWO’s economic efficiency is demonstrated to be dependent on the volume of fluid processed, not upon the PFAS concentration or formulation chemistries, suggesting that the SCWO technology would be even more economical for highly contaminated streams.