The overall goal of this project is to develop a regenerable resin sorbent technology that is effective for treating the full diversity of per- and polyfluoroalkyl substances (PFAS) present in groundwater impacted by aqueous film-forming foam (AFFF). Specifically, researchers hypothesize that a combination of commercially available regenerable resin sorbents (ion exchange + non-ionic resins) can be applied to remove the full range of PFAS (including emerging classes of PFAS recently identified through the application of high resolution mass spectrometry methods) and co-occurring chemicals in AFFF-impacted groundwater, and that the sorbents can be regenerated using an innovative approach where destruction of the PFAS can be accomplished efficiently within the waste regenerant concentrates. The preliminary data show successful removal of all PFAS identified in an AFFF (by LC-QToF-MS screening of ~1500 PFAS structures) following sequential treatment with an anion exchange resin plus a non-ionic resin, indicating that the project framework holds exceptional promise for mitigating current and future liabilities associated with AFFF-impacted groundwater sources at DoD facilities.
Experiments and modeling will be combined to test the hypotheses outlined above and meet the project objective of delivering a cost-effective and sustainable remedial technology capable of addressing the full range of PFAS present in AFFF-impacted groundwater. The project team will apply a unique process systems engineering framework that integrates life cycle cost analysis (LCCA) and life cycle assessment (LCA) modeling throughout the work to guide experimental design decisions and quantify the impacts of experimental results on the overall treatment train costs and life cycle environmental impacts. Experimental work will be aimed at (i) identifying critical resin characteristics that control both adsorption of different classes of PFAS and regenerability, (ii) identifying combinations and sequences of regenerable resins capable of successfully removing the full range of PFAS identified in AFFF, (iii) assessing the influence of co-occurring chemicals and co-occurring chemical pretreatment steps on resin adsorption of PFAS, (iv) identifying mixtures of salt brines and alcohol co-solvents needed to desorb PFAS and regenerate resins, (v) assessing potential for co-solvent recovery from waste regenerant concentrates and reuse, and (vi) evaluating the effectiveness of electrochemical and photochemical treatment processes for destroying PFAS in the waste regenerant solutions. Application of the process systems engineering approach will also enable systems-level quantification of the economic and life cycle environmental impact tradeoffs associated with individual process design decisions like the selection of resins, the resin regeneration protocol, and the strategy for managing and/or recycling the regenerant waste concentrate stream.
Successful completion of this research will provide the DoD with a cost-effective and environmentally sustainable treatment technology that can be applied to improve management of AFFF impacted sites. The process systems engineering models that will be established with integrated LCCA and LCA will also provide for site-specific design modifications tailored to the composition of PFAS, co-occurring chemicals, and natural groundwater constituents at the site. This will serve the DoD by providing a viable path for mitigating significant liabilities and accelerating site closure plans. (Anticipated Project Completion - 2023)
Boyer, T.H., A. Ellis, Y. Fang, C.E. Schaefer, C.P. Higgins, and T.J. Strathmann. 2021. Life Cycle Environmental Impacts of Regeneration Options for Anion Exchange Resin Remediation of PFAS Impacted Groundwater. Water Research, 207:117798. doi.org/10.1016/j.watres.2021.117798.
del Moral, L.L., Y.J. Choi, and T.H. Boyer. 2020. Comparative Removal of Suwanee River Natural Organic Matter and Perfluoroalkyl Acids by Anion Exchange: Impact of Polymer Composition and Mobile Counterion. Water Research, 178:115846. doi.org/10.1016/j.watres.2020.115846.
Dietz R., C. Kassar, and T.H. Boyer. 2021. Regeneration Efficiency of Strong-base Anion Exchange Resin for PFAS. AWWA Water Science, 3(6):e1259. doi.org/10.1002/aws2.1259.
Ellis, A., C.J. Liu, Y. Fang, C. Bellona, T.H. Boyer, C.E. Schaefer, C.P. Higgins, and T.J. Strathmann. 2022. A Pilot Study Comparison of Regenerable and Emerging Single-use Anion exchange Resins for Treatment of Groundwater Contaminated by Per- and Polyfluoroalkyl Substances (PFASs). Water Research, 223:119010. doi.org/10.1016/j.watres.2022.119019.
Fang Y., A. Ellis, Y. Choi, T. Boyer, C.P. Higgins, C.E. Schaefer, and T.J. Strathmann. 2021. Removal of Poly- and Perfluoroalkyl Substance (PFAS) in Aqueous Film-forming Foam (AFFF) Impacted Water Using Ion Exchange and Non-ionic Resins. Environmental Science and Technology, 55(8):5001-5011. doi.org/10.1021/acs.est.1c00769.
Fang, Y., P. Meng, C. Schaefer, and D. Knappe. 2023. Removal and Destruction of Perfluoroalkyl Ether Carboxylic Acids (PFECAs) in an Anion Exchange Resin and Electrochemical Oxidation Treatment Train. Water Research, 230:119522. doi.org/10.1016/j.watres.2022.119522.
Kassar C., C. Graham, and T.H.Boyer. 2022. Removal of Perfluoroalkyl Acids and Common Drinking Water Contaminants by Weak-base Anion Exchange Resins: Impacts of Solution pH and Resin Properties. Water Research X, 17:100159. doi.org/10.1016/j.wroa.2022.100159.
Schaefer, C.E., D. Tran, Y. Fang, Y. Choi, C.P. Higgins, and T.J. Strathmann. 2020. Electrochemical Treatment of Poly- and Perfluoroalkyl Substances in Brines. Environmental Science: Water Research and Technology, 6:2704-2712. doi.org/10.1039/d0ew00377h.