Abstract
<jats:p>The Department of Defense (DoD) faces significant environmental challenges regarding the disposal of legacy aqueous film-forming foam (AFFF) containing persistent PFAS. This project, led by the US Army Engineer Re-search and Development Center (ERDC), evaluates the performance of the 374Water AirSCWO™ 6 system in destroying PFAS within AFFF. During the demonstration, 100 gal. of AFFF were treated, successfully meeting US EPA maximum contaminant levels (MCLs) for PFAS in the liquid effluent. The system achieved a destruction removal efficiency of 99.9993% for total PFAS as analyzed via the total oxidizable precursor (TOP) Assay (42 PFAS). Stack emissions remained below 500 g/h for vola-tile fluorinated compounds as measured by Other Test Method (OTM)–50. While the demister condensate exceeded US EPA PFAS MCLs, the total volume was negligible at less than 0.5 L. Energy efficiency analysis showed a consumption of 1.15 MWh per cubic meter of AFFF per order of magnitude of 42 PFAS destroyed and 12.9 kWh per gram of PFAS destroyed. Treatment costs varied and may range from $47 to $238 per gallon of AFFF. These results demonstrate the effectiveness of super-critical water oxidation technology for a safer disposal of legacy AFFF concentrates.</jats:p>