A Synergistic Platform for Defluorination of Perfluoroalkyl Acids (PFAAs) through Catalytic Reduction Followed by Microbial Oxidation

Dr. Bruce Rittmann | Arizona State University

ER20-1286

Objective

The objective of this proof-of-concept project is to demonstrate a novel synergistic platform for efficient defluorination of per- and polyfluoroalkyl substances (PFAS), mostly perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), and to explore strategies to optimize the catalytic-biological synergy. The concept begins with a H2-based membrane precious-metal-film reactor (H2-MPfR) to reductively defluorinate PFOA and PFOS to less-fluorinated octanoic and octanesulfonic acids. These less-fluorinated compounds are then oxidatively defluorinated and mineralized by microorganisms in a O2-based membrane biofilm reactor (O2-MBfR). Although the effort is strongly application-driven, it also will contribute to understanding of the fundamental factors controlling reductive and oxidative defluorination of PFOA and PFOS, processes that occur in groundwater and wastewater treatment settings. In addition, results of this research will provide scientific guidance to research that extends to treating other perfluoralkyl acids (PFAAs).

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Technical Approach

Bench-scale experiments will be conducted to maximize PFOA and PFOS removal via reductive defluorination in the H2-MPfR and the cometabolism of partially fluorinated octanoic and octanesulfonic acids via oxidative defluorination and mineralization in the O2-MBfR. The experiments will focus on strategies to optimize the efficiency and selectivity of PFOA/PFOS defluorination in the H2-MPfR and to stimulate the growth of PFAA-degrading bacteria. The best strategies will be revealed by exploring changes in the catalyst characteristics in H2-MPfR and the microbial community structure in the O2-MBfR. A cost analysis will be conducted to provide data for end users to consider this novel synergistic platform. The experimental and cost data can then be used to guide pilot-scale or field-scale study in a next step.

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Benefits

This synergistic platform is for ex situ treatment, but the principles can be adapted for synergistic in situ treatment of groundwater contaminated by PFAAs, of which the degradation product could be less- or non-fluorinated counterparts. This project also will contribute to understanding of the fundamental factors controlling cometabolic biodegradation of fluoroalkyl compounds, processes that occur during in situ and ex situ groundwater treatment settings.

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Points of Contact

Principal Investigator

Dr. Bruce Rittmann

Arizona State University

Phone: 480-727-0434

Fax: 480-727-0889

Program Manager

Environmental Restoration

SERDP and ESTCP

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