Grantee Research Project Results
Final Report: Electrochemical Pretreatment of PFAS-Contaminated Aqueous Effluents
EPA Contract Number: 68HERD19C0011Title: Electrochemical Pretreatment of PFAS-Contaminated Aqueous Effluents
Investigators: Lee, Katherine
Small Business: Faraday Technology, Inc.
EPA Contact: Richards, April
Phase: I
Project Period: May 1, 2019 through October 31, 2019
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2019) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR): Phase 1 (2019) , Small Business Innovation Research (SBIR) , SBIR - Water Quality
Description:
The purpose of the research conducted in this program was to demonstrate the feasibility of pulsed-waveform FARADAYIC® ElectroCatalysis for efficient, cost-effective pretreatment of waste streams for removal of per-/polyfluorinated alkyl species (PFAS). PFAS are used across a broad range of industries for a wide variety of applications, including carpeting, apparel, upholstery, metal plating and firefighting foams. However, research has demonstrated that these compounds are highly refractory and bio-accumulative when released to the environment, and have the potential to cause adverse health effects, such as low birth weight, accelerated puberty, cancer, and skeletal, liver, kidney and other problems. The technology at the focus of this program is needed due the presence of PFAS in various industrial waste streams and landfill leachates, and their resistance to traditional methods for remediation of chemical contaminants. While direct-current electrocatalysis has been shown to be somewhat effective for PFAS remediation, a key goal of this program was to demonstrate significant techno-economic improvements in PFAS destruction processes via introduction of FARADAYIC® ElectroCatalysis.
In this Phase I SBIR program, Faraday Technology implemented FARADAYIC® ElectroCatalysis in two electroreactor form factors, a custom beaker-scale stirred configuration and a commercial flow-through configuration. Multiple anode electrocatalyst materials were tested in the beaker apparatus, including bare and polymer-coated metallic (nickel or titanium) electrodes and boron-doped diamond electrodes. The commercial reactor, procured from vendor Element Six Technologies (Santa Clara, CA), a potential commercialization partner, was equipped with a four-cell stack of monolithic boron-doped diamond electrodes. In order to reduce the complexity of the experimental work in this Phase I program, a single representative chemical from the PFAS family, perfluorooctanesulfonate (PFOS), was selected as a model compound for study.
FARADAYIC® ElectroCatalysis destruction of PFOS was examined in these two electroreactor form factors in the presence of two supporting electrolyte compositions, (i) 100 mM sodium sulfate and (ii) 100 mM monopotassium phosphate. While these compositions are simpler than are likely to be observed in industrially-relevant streams, they did still allow a measure of investigation of the dependence of PFOS destruction performance by FARADAYIC® ElectroCatalysis on the background liquid composition. The extent of FARADAYIC® ElectroCatalysis destruction of PFOS was evaluated by two methods, (i) accumulation of the fluoride ion byproduct via ion-specific electrode (ISE) and (ii) standardized LC-MS analysis, via a Modified EPA 537 method. The fluoride ISE provides a semi-quantitative but extremely rapid analytical method, which was used for initial screening of anode electrocatalysts and FARADAYIC® ElectroCatalysis operating parameters. Results from selected FARADAYIC® ElectroCatalysis tests were confirmed via subcontracting the fully quantitative LC-MS method to a third-party vendor.
The experimental data were used to develop capital and operating expense estimates for two model applications, one for treatment of rinse waters from hexavalent chromium plating and one for treatment of landfill leachate. The scales of these two industrially-representative cases were selected based upon literature reports of installations exhibiting PFAS contamination at levels requiring pretreatment/remediation.
Summary/Accomplishments (Outputs/Outcomes):
The FARADAYIC® ElectroCatalysis tests revealed that, of the materials tested, the boron-doped-diamond (BDD) catalyst yielded markedly superior performance. Both BDD-equipped reactors demonstrated PFOS destruction of 97%+ within one hour of processing in multiple tests, as observed by fluoride ISE and as confirmed in select experiments by the quantitative LC-MS analysis. Interestingly, the performance of FARADAYIC® ElectroCatalysis for PFOS destruction was found to be significantly influenced by the composition of the supporting electrolyte: in particular, destruction appeared more facile in the monopotassium phosphate matrix as compared to the sodium sulfate matrix. This composition dependence of FARADAYIC® ElectroCatalysis performance is an important factor to consider, in that some measure of "calibration study" may be required as part of the process of applying the technology to new waste streams requiring pretreatment in a consistent and reliable way.
The pulsed-waveform FARADAYIC® ElectroCatalysis destruction process exhibited favorable technoeconomic performance when operated with waveform parameters identified as preliminarily optimal, with specific energy inputs per log-reduction in PFOS of 3-11 kWh/m3-log (competitive with best-performing catalysts from literature) and area-normalized heterogeneous first-order destruction rate constants of 1.4-5.4 × 10-3 m/s (superior to best-performing catalyst/reactor configurations by approximately one order of magnitude). Depending on the specifics of a particular application of the technology, inclusion of an upstream PFAS pre-concentration and/or PFAS isolation process unit may be desirable in order to avoid complicating factors arising from the background composition of the stream to be pre-treated.
Conclusions:
Based on the Phase I data and analysis, Faraday anticipates that pulsed FARADAYIC® ElectroCatalysis embodies a revolutionary, novel capability for destruction of PFAS in industrial/landfill wastewater/leachate streams. The FARADAYIC® ElectroCatalysis reactors are compact, are significantly more energy- and cost-efficient than the majority of competitor technologies, and can be adapted to a wide variety of streams of industrial relevance. More work is required in order to establish specific operating parameters for waste stream(s) of interest to Phase II/III commercialization partner(s), as part of a larger-scale demonstration of the technology.
The economic analysis performed as part of this Phase I SBIR program strongly supports the relevance of the FARADAYIC® ElectroCatalysis approach for PFAS destruction to various applications of commercial interest. For both the hexavalent chromium plating and landfill leachate model cases studied, the 20-year annualized costs to reduce PFAS levels to below the 70-ppt EPA Lifetime Health Advisory limit ($1680/yr for treatment of 200 gal/day of rinse water and $23,900/yr for treatment of 5500 gal/day of leachate from a 250-acre landfill) seem eminently reasonable for typical operations. The intrinsically scalable nature of electrochemical hardware makes it highly likely that larger-scale applications would also find the technology economically appealing. Discussions with our commercialization partners [Fraunhofer USA Center for Coatings and Diamond Technologies (East Lansing, MI), U.S. Ecology (Livonia, MI), Jacobs Engineering (Dallas, TX), Coventya (Brooklyn Heights, OH), and CONDIAS (Itzehoe, Germany)] all support the appeal of the FARADAYIC® ElectroCatalysis technology as a cost-effective, efficient, scalable technology for the pretreatment of industrial and landfill waste streams for PFAS destruction.
SBIR Phase II:
Electrochemical Pretreatment of PFAS-Contaminated Aqueous Effluents | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.