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High Temperature Thermal Treatment of PFAS
Citation:
Krug, Jonathan D. High Temperature Thermal Treatment of PFAS. Board of Scientific Counselors, RTP, NC, October 12 - 14, 2021.
Impact/Purpose:
PFAS are a unique and stable class of compounds that are useful in a large number of applications. These traits have led to PFAS being present in numerous waste streams and products, like aqueous film forming foams (AFFF). It has been found that PFAS can bioaccumulate and can have harmful effects in humans and other animals. PFAS in the gas phase also can contribute to global warming. It is important to find methods to destroy PFAS without emitting harmful PFAS or products of incomplete destruction. Investigations into the incineration of PFAS and the development of a method to help determine incinerators' efficacies for PFAS destruction are outlined here, and some preliminary results are shown. Determining the temperatures and residence times needed to completely destroy PFAS is vital to ensure PFAS and PFAS by-products are not released into the environment. This information is important for the Department of Defense, local communites, and the general public.
Description:
EPA’s Office of Research and Development is performing a combined experimental and theoretical study to examine thermal destruction of per and poly-fluorinated alkyl substances (PFAS) in a pilot-scale vertical tunnel combustor that is firing natural gas as its primary fuel. Testing has so far been performed on three C1 and C2 PFAS compounds (CF4, CHF3, and C2F6) and initial tests of Aqueous Film Forming Foam (AFFF) have commenced. These tests 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, including through the flame as well as various locations 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) evaluation of a 3-D reacting flow model based on C1-C3 fluorinated organic chemical reactions and kinetics compiled by the National Institute of Standards and Technology (NIST) and available from the literature, and how it predicts destruction efficiencies of the injected 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., HF). This presentation will discuss the current experimental program, experimental results, future plans, and potential enhancements to the modeling effort to more completely encompass likely operational scenarios both in the laboratory and in the field.