Theme: 07. Per- and Polyfluorinated Alkyl Substances (PFAS)

Topic Area: 7c. Ex Situ PFAS Destruction Technologies

Formatted Title:

Pulse Electrochemical Oxidative Destruction of PFAS: A Simple Method for Improving Water Treatment Efficiency

Background/Objectives:

Growing regulation of per-/polyfluorinated species (PFAS) has prompted significant research into methods to remove and destroy PFAS in aqueous solutions. One promising treatment strategy uses electrochemical oxidation to completely mineralize PFAS. Traditional electrochemical oxidation systems rely on direct current waveforms to drive PFAS destruction. However, the high cost, low energy efficiency, and poor selectivity of traditional direct current electrochemical oxidation has limited the commercial uptake of this approach. This presentation will discuss a simple approach to improve the performance of commercial electrochemical reactors for the electrochemical oxidative PFAS destruction through the use of pulse waveforms.

Approach/Activities:

To validate the ability to enhance the performance of commercially electrochemical reactors for PFAS destruction via pulse waveforms, Faraday rigorously characterized the PFAS destruction performance of a boron doped diamond reactor (CONDIACELL^®) using direct current and pulse waveforms on the laboratory scale. Using the CONDIACELL^® as a case study, Faraday compared the PFAS destruction performance of direct current and pulse waveforms in landfill leachate surrogates, highly saline brine solutions, and foam fractionate derived from landfill leachate. PFAS destruction performance was evaluated based on the kinetics and energy efficiency of PFAS destruction as well as the robustness of reactor performance over time.

Results/Lessons Learned:

In these studies, Faraday demonstrated that pulse waveforms can improve both the rate and energy efficiency of PFAS destruction (relative to traditional direct current electrochemical oxidation) in the CONDIACELLL^® reactor. The use of pulse waveforms was also found to enable more stable PFAS destruction performance over longer timescales. Additional benefits of pulse waveforms identified through this case study include the ability to mitigate changes in solution pH, precipitate formation/electrode fouling, and hazardous foaming in highly concentrated foam fractionate. The improved performance of pulse waveforms (relative to traditional direct current treatment) is attributed to the mitigation of parasitic and energy intensive side reactions (e.g., oxygen evaluation).

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Maria Inman