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Pilot-Scale Thermal Destruction of Perfluorinated Akyl Substance (PFAS) Compounds
Citation:
Krug, Jonathan D., W. Roberson, P. Lemieux, C. Lee, J. Ryan, P. Kariher, E. Shields, S. Jackson, L. Wickersham, Bill Linak, P. Burnette, J. Nash, L. Virtaranta, AND B. Preston. Pilot-Scale Thermal Destruction of Perfluorinated Akyl Substance (PFAS) Compounds. 39th International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors, West Palm Beach, FL, May 05 - 06, 2022.
Impact/Purpose:
This paper reflects work performed on the Rainbow Furnace in EPA’s RTP facilities, where model PFAS refrigerant compounds (CF4, C2F6, and CHF3) and Acqueous Film Forming Foam (AFFF) were fed into the furnace through the flame as well as through several post-flame positions at various firing rates, temperatures and residence times. Various targetted and non-targetted samples were taken with the intention of reporting Destruction Efficiencies and/or Products of Incomplete Combustion. Selected results will be compared to output of kinetic incinerator model (the Configured Fireside Simulator, CFS) originally developed by Reaction Engineering International for the HSRP, with PFAS-specific additions funded from both SHC5.4.4 and the PITT. The presentation's first author is Jonathan Krug (CEMM, AMCD), other authors include several researchers from CEMM, Paul Lemieux (CESER, HSSMD), Jacobs contractor, and the model’s developers at Reaction Engineering International. This work represents several unique applications of applied combustion science, where 1) experiments were performed using model compounds in a real combustion system, real-time measurements were performed of the injected compound, and results are compared to model predictions of those same trace gas-phase constituents; and 2) PFAS containing liquid was injected into an incinerator under controlled conditions, and targetted and non-targetted samples were collected for analysis of destruction and formation of products of incomplete combustion. This represents a significant potential enhancement in knowledge regarding the thermal treatment of PFAS-containing waste and in sampling methodologies. This abstract was internally reviewed by an ORD researcher and will be sent to the Approval Committee for the Internation Conference on Thermal Treatment Technologies & Hazardous Waste Combustors (IT3) for external review. If accepted a subsequent presentation will be created and cleared separately for presentation at the IT3 Conference May 5-6, 2022.
Description:
EPA’s Office of Research and Development is performing a combined experimental and theoretical study to examine the thermal destruction of per and poly-fluorinated alkyl substances (PFAS) in a pilot-scale 85 kW (rated) down-fired natural gas combustor. Testing has been performed on three PFAS compounds (CF4, CHF3, and C2F6) and a legacy formulation Aqueous Film Forming Foam (AFFF). To facilitate testing of AFFF, a custom dual-fluid atomization technique for high-temperature injection of fluorinated liquids was developed. These experimental and modeling efforts are directed towards 4 primary objectives: 1) evaluate effectiveness of the thermal destruction process when these compounds are injected into different parts of the furnace and experience different thermal environments, including through the flame and downstream of the flame; 2) evaluation of products of incomplete combustion (PICs) that may be formed based on injected PFAS compounds and injection locations; 3) development of a 3-D reacting flow model based on methane-air combustion and C1-C3 fluorinated organic chemical kinetics and how it predicts destruction efficiencies of the injected C1-C2 compounds and the trace PICs (compounds and concentrations) that may be subsequently formed; and 4) development of measurement techniques that are effective for quantifying the combustor emissions including the parent compound, relevant trace PICs, and major flue gas species (e.g., hydrofluoric acid). This presentation will discuss the current experimental program, experimental results from EPA’s pilot-scale combustor, comparisons to the evolving 3-D reacting flow model, development of additional PFAS reaction kinetics, and future research plans.