Novel Treatments for Per- and Polyfluoroalkyl Substance (PFAS)-Impacted Matrices
Aqueous film-forming foam (AFFF) formulations have been used to suppress liquid fuel fires, resulting in many sites impacted by per- and polyfluoroalkyl substances (PFAS). Due to their chemical structure, PFAS are very stable in the environment and relatively resistant to biodegradation, photo-oxidation, direct photolysis, and hydrolysis, making treatment difficult and costly.
In 2022, SERDP selected projects to develop cost-effective remedial technologies for matrices impacted by PFAS resulting from the use of AFFF formulations. These SERDP projects address the following research goals: developing cost effective treatment approaches for PFAS-impacted matrices, developing cost effective approaches for complete destruction of PFAS bound onto spent media, evaluating treatment technologies using field-impacted media containing PFAS mixtures and common environmental treatment complications, and developing treatment train approaches to cost-effectively treat PFAS and facilitate treatment of co-occurring chemicals.
Dr. Kung-Hui (Bella) Chu at Texas A&M University will develop an integrated treatment system for the effective treatment of PFAS-laden soils in source zones based on the “Release-Capture-Destruction” concept in a proof-of-concept project. These results will fill knowledge gaps about the poorly understood effect of co-occurring hydrocarbon surfactants on the fate and biotransformation of PFAS and decipher the factors controlling the biodegradation of the soil-bound precursors into more mobile perfluoroalkyl acids (PFAA) for subsequent treatment ( Project Overview).
At Auburn University, Dr. Dengjun Wang’s proof-of-concept project will engineer a cost-effective, sustainable biochar-surfactant system (BSS) to treat PFAS-impacted groundwater via enhanced sorption and destruction by advanced reduction processes using hydrated electrons. This project will develop a cost-effective “all-in-one” system to contribute to DoD efforts to sustainably remediate PFAS-impacted groundwater ( Project Overview).
Dr. Jon Chorover and his team at the University of Arizona will explore the capability of synthetic colloidal polymers to serve as injectable adsorbents in saturated sand and gravel aquifer systems impacted by PFAS in a proof-of-concept project. This technology will address the urgent need for in situ remediation of groundwater impacted by PFAS ( Project Overview).
Dr. Tingting Wu from the University of Alabama in Huntsville will demonstrate that efficient destruction of PFAS can be achieved using plasmonic catalysts in a proof-of-concept project. Results from this project will verify the feasibility of utilizing localized surface plasmon resonance (LSPR) of plasmonic nanostructures to generate reactive redox species for efficient PFAS destruction and lay a solid groundwork for further development of integrated oxidation-reduction PFAS treatment processes ( Project Overview).
At GSI Environmental, Dr. Charles Newell and his team will explore the use of gas sparging as an effective and efficient first stage of a treatment train solution where PFAS are first concentrated, extracted, and destroyed. This research will provide a novel way to avoid expensive treatment of PFAS-impacted subsurface media by allowing for long-term retention of PFAS in the subsurface under an enhanced-monitored natural attenuation (MNA) type framework (Project Overview available soon).
Additionally, Dr. Charles Newell at GSI Environmental will determine whether PFAS-impacted groundwater plumes that mix with saline groundwater near marine shorelines significantly increase PFAS sorption via “salting out” in this proof-of-concept project. “Salting out” with the addition of tidal pumping may reduce nearshore PFAS concentrations in groundwater naturally by sequestering PFAS via sorption before the PFAS enter sensitive bays, estuaries, or open oceans, which could preclude the need for expensive groundwater control systems at every shoreline site ( Project Overview).
Dr. Michael Wong at Rice University will further develop boron nitride (BN)-based materials to treat PFAS-impacted sites economically and efficiently via chemical-free PFAS photocatalytic degradation. This proof-of-concept project will determine the field applicability of the BN photocatalytic approach for PFAS-impacted sites by testing simulated and natural waters as well as wash streams ( Project Overview).
At Oregon Health & Science University, Dr. Paul Tratnyek and his team will explore combining dissolving metal reduction (DMR) with zerovalent magnesium and mechanochemical mixing (MCM) by ball milling as a strategy to produce rapid, deep, and sustained defluorination of PFAS via solvated electrons. This proof-of-concept effort will ascertain whether the DMR-MCM process will nearly completely degrade PFAS in both liquid matrices and soil matrices ( Project Overview).
Dr. Yida Fang from CDM Smith will develop a modified ultraviolet (UV)-reductive treatment system via hydrated electrons that utilizes the amphipathic properties of PFAS at the gas-water interface to enhance PFAS reductive defluorination and significantly reduce treatment energy consumption. This proof-of-concept project will provide the DoD with the basis for designing a high-performance PFAS removal and energy-efficient UV-reductive treatment system that can be applied to improve the remediation of AFFF-impacted source waters and reduce the total energy cost during treatment ( Project Overview).
At Aptim Federal Services, Dr. Paul Hatzinger and his team’s proof-of-concept project will improve the understanding of potential cometabolic transformation reactions of polyfluoroalkyl precursor compounds, and the extent to which these reactions lead to the formation of extractable PFAAs. This project should lead to a better understanding of these biological conversions, as well as potential field approaches to convert strongly sorbed precursors to more treatable PFAAs in AFFF source areas ( Project Overview).
Dr. Selma Mededovic from Clarkson University will demonstrate the technical feasibility of using a novel plasma spinning disc reactor for the complete destruction of PFAS in undiluted AFFF in this proof-of-concept project. This effort will expand upon the proven plasma-based processes to treat undiluted AFFF with the aim of ultimately destroying PFAS on site ( Project Overview).
Also at Clarkson University, Dr. Yang Yang will build a novel treatment train by integrating electrochemical oxidation (EO) and ultraviolet/sulfite (UV/S) reduction modules to destroy all PFAS in complicated water matrices, which often includes organic compounds and salts. This proof-of-concept project will improve understanding of the destruction and defluorination of short-chain PFAS by oxidation and reduction pathways, demonstrating that PFAS can be readily decomposed in a rationally designed treatment train ( Project Overview).
Dr. Arjunkrishna Venkatesan at Stony Brook University will explore the uses of air bubbles to extract and remove PFAS from impacted water and soil in this proof-of-concept project. An important advantage of this approach is that the air bubbles can serve as a pre-concentration step to be coupled with other destructive treatment technologies to make the overall PFAS destruction process more efficient ( Project Overview).
At Battelle Memorial Institute, Dr. Kavitha Dasu’s proof-of-concept project will explore the feasibility of the application of supercritical water oxidation (SWCO) technology to destroy PFAS-impacted solid matrices in the form of a soil or sludge slurry. This in situ treatment technology will effectively address PFAS-impacted groundwater and thereby address issues such as off-site migration from source areas ( Project Overview).
Dr. Deepak Kirpalani from the National Research Council of Canada will develop a synergistic approach for applying a hybrid pulsed electrosorptive cavitation process train to degrade high-priority PFAS toward mineralization in aqueous systems. This proof-of-concept project will provide further understanding of increased gas-liquid interfaces other than liquid surface effects in plasma treatment ( Project Overview).
At the Science, Technology, & Research Institute of Delaware, Dr. Seetha Coleman-Kammula will determine whether swellable ionomers outperform conventional sorbents in removing a broad range of PFAS from water in this proof-of-concept project. These ionomers may replace granular activated carbon (GAC) and single-use ion exchange (IX) resins as faster and higher capacity sorbents that can be quickly regenerated on-site without creating co-solvent or brine waste streams ( Project Overview).
More information and reports from these projects will be provided on the individual project webpages as they become available. To learn more about PFAS research and initiatives, browse the SERDP and ESTCP website for related program overviews and updates.