Per- and polyfluoroalkyl substances (PFAS) are present in aqueous film forming foam (AFFF) used by the Department of Defense (DoD) and other organizations to extinguish fires. SERDP and ESTCP have been funding research and demonstrations on a number of fronts to improve our ability to manage sites impacted by these chemicals. In 2020, SERDP began funding a group of projects to improve the understanding of biodegradation processes and biological treatment strategies for PFAS in the subsurface. Described below are the five projects that were selected for funding, which includes three projects that are one-year, proof-of-concept approaches.

• At Princeton University, Dr. Peter Jaffe and his team will improve the understanding of biodegradation processes carried out by an autotrophic bacterium (Acidimicrobiaceae sp. A6) in an anoxic environment and propose pathways for the biotransformation / mineralization process. By demonstrating that there is microbial process that can mineralize PFAS, and under specific circumstances, the process can be stimulated or bioaugmented in soil / aquifer environments, these results will lead to novel methods for in situ PFAS bioremediation. (Project Overview)

• Dr. Jinxia Liu from McGill University and her team are investigating the microbial desulfonation process and “one-carbon removal pathways” that are common to fluorotelomers in order to work towards complete defluorination. The results of this project will provide an understanding of the microorganisms, genetics, and biochemistry involved in biological C-S and C-F cleavage. (Project Overview)

• Dr. Yujie Men from the University of California, Riverside and her team will obtain a thorough mechanistic understanding of microorganisms carrying out reductive defluorination of perfluorinated alkyl acids (PFAAs), the defluorination pathways, and the feasibility of use of microbial defluorination for cost-effective treatment strategies of AFFF-impacted water at DoD installations. (Project Overview)

• At Rice University, Dr. Pedro Alvarez and his team are identifying bacterial strains that are capable of producing superoxide at high rates and assessing their capacity to degrade model PFAS. The results of this proof-of-concept project will facilitate the development of both in situ and ex situ bioremediation strategies and lead to reduced treatment costs at DoD sites. (Project Overview)

• Dr. Bruce Rittman and his team will demonstrate a novel synergistic platform for efficient defluorination of PFAS, mostly perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) and explore strategies to optimize the catalytic-biological synergy. The results of this research will contribute to the understanding of the fundamental factors controlling reductive and oxidative defluorination of PFOA and PFOS, processes that occur in groundwater and wastewater treatment settings, and provide scientific guidance to research that extends to treating other PFAAs. (Project Overview)

Summaries of these research projects are available on the SERDP and ESTCP website and all reports originating from these efforts will be available from the project webpages.