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Supercritical Water Oxidation for Aqueous Phase Treatment of Concentrated PFAS Aqueous Foam Forming Fluid
Citation:
Sahle-Demessie, Endalkac, K. Liberty, E. Shields, C. Berg, S. Jackson, I. George, AND J. Follin. Supercritical Water Oxidation for Aqueous Phase Treatment of Concentrated PFAS Aqueous Foam Forming Fluid. American Chemical Society Annual Meeting, Indianapolis, IN, March 26 - 30, 2023.
Impact/Purpose:
The presentation includes performance of industrial scale Supercritical water oxidation of AFFF. The results show high destruction efficiencies and no measurable gas and liquid emissions of HF or organofluorine compounds.
Description:
Supercritical Water Oxidation (SCWO) process for hazardous waste destruction uses the temperature and pressure of water above the critical point (374 oC, and 22.1 MPa) to degrade hazardous organic pollutants into CO2, water, SO2, and other benign compounds. Using SCWO technology currently available on the market, we have conducted tests on the removal efficacy and destruction of per- and polyfluoroalkyl substances (PFAS) within aqueous film-forming foam (AFFF). The complete miscibility of hazardous pollutants with oxidizing gases in a single phase at moderate temperature and molecular densities affords high destruction efficiencies with a residence time of less than one minute. Aqueous film-forming foam mixed with water at ratios (of 34 to 212) was fed to the SCWO reactor at an average rate of 9.1 L/min. Samples were collected from both influent and effluent streams – including gaseous emissions. In all tests, PFAS and total organic carbon (TOC) destruction efficiencies were > 99.99%. PFAS target compounds were not detected above the background level in the gas analyses. The effluent from the process is water, with dissolved NaF and gas consisting of CO2, O2, and oxidation products of the diesel used for energy generation with less than 10 ppm of CO. There was no fluorine-containing compounds in the gaseous emissions and particulates.