Grantee Research Project Results
Final Report: Removing PFAS in Investigation Derived Wastes (IDW) with Electrocoagulation and Electrochemically Activated Persulfate
EPA Contract Number: 68HERC20C0033Title: Removing PFAS in Investigation Derived Wastes (IDW) with Electrocoagulation and Electrochemically Activated Persulfate
Investigators: Christenson, Mark
Small Business: AirLift Environmental, LLC
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2020 through August 31, 2020
Project Amount: $99,004
RFA: Small Business Innovation Research (SBIR) - Phase I (2020) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Mining , SBIR - Mining and Mine Waste Management
Description:
Per- and Polyfluoroalkyl substances (PFAS) have been used since the mid-1970s as components of aqueous film forming foams (AFFFs). Because of their unique ability to resist heat and block oxygen, PFAS-containing firefighting foams were used at aircraft service centers where fire-fighting training operations were routinely performed. With more than 3 decades of repeated use at hundreds of military facilities across the USA, PFAS have been detected in 61% of the groundwater samples taken around Department of Defense (DoD) facilities with concentrations ranging from low ppb to low ppm concentrations.
Now that toxicological studies have linked PFAS with a host of health problems, including kidney, testicular, bladder, and prostate cancer, as well as immune, reproductive, and hormonal dysfunction, the DoD has an environmental liability to delineate the extent of contamination at sites where firefighting foams were routinely used. To delineate the extent of contamination, many of these sites are undergoing intensive site investigations and generating large quantities of investigation derived wastes (IDW). Current IDW disposal practices of landfilling or incineration are costly and burdensome. The goal of this proposal was to develop an ex situ remedial treatment for the PFAS-contaminated IDW. We initially proposed using electrocoagulation (EC) combined with chemical oxidation and electrochemically activated persulfate (EAP) to remove PFAS and associated co-contaminants. As research progressed during this Phase I project, our focus shifted to using electrocoagulation and electrochemical oxidation with boron-doped diamond electrodes as the main remediation technologies. Laboratory studies identified the treatment parameters most useful in achieving optimum efficacy in removing PFAS while pilot-scale experiments developed the technology prototypes that could be scaled up for commercialization.
Summary/Accomplishments (Outputs/Outcomes):
To contribute to the overall goal of removing PFAS from IDW, AirLift and the University of Nebraska (UNL) conducted a series of laboratory batch experiments using a boron-doped diamond (BDD) anode to electrochemically oxidize PFAS compounds. An advantage electrochemical oxidation has over other technologies, is that BDD anodes can initiate an electron removal from both the ionic heads of PFOA and PFOS-like structures.
We used three different methodologies to generate results. The first approach used 14C-PFOA and tracked changes in 14C in solution. By using 14C-PFOA alone, starting concentrations were in the parts per billion range (µg/L). We also combined 14C-PFOA with unlabeled PFOA (10 or 100 mg/L). This allowed us to measure the PFOA removal and the generation of fluoride (our second measurement) by ion chromatography. The third methodology used LC/MS/MS to measure PFOA and PFOS with starting concentrations in the parts per billion range. All three methodologies provided direct evidence that electrochemical oxidation via BDD electrodes is effective in degrading PFAS within hours.
Airlift's current prototypes for IDW have the capacity to recycle and treat multiple pore volumes of IDW per day (20-27 times per day), are highly mobile and can be setup to treat soil or groundwater in numerous 55-gallon drums or larger roll-off dumpsters. Prototypes that use electrochemical oxidation and electrochemical coagulation were both developed and are currently being tested. Treatment costs are conservatively estimated to be 50% less than incineration.
Conclusions:
· AirLift has created two prototype PFAS IDW Treatment Kits.
· Prototypes for treating IDW via electrochemical oxidation or electrocoagulation are effective in decreasing PFAS concentrations.
· Shorter chain degradation products formed during the destruction of the parent contaminant are also mineralized by our electrochemical oxidation treatment method.
· LC/MS/MS analysis indicates parts per billion (µg/L) PFAS concentrations can easily be degraded by electrochemical oxidation using BDD anodes.
· Changing electrolyte formulation (Na2SO4 versus KH2PO4) did not affect degradation rates, whereas, changing electrolyte concentration did affect degradation rates.
· By increasing amperage, observed kinetics change from current-controlled (zero-order) to mass-transfer controlled (first-order).
· Combining a BDD anode with a Platinum/Titanium cathode was most effective in increasing PFOA degradation
· Lowering pH of solution treated with BDD anode was inconsistent in improving PFAS degradation kinetics. Results likely dependent on initial bulk solution pH.
· Care must be taken when submerging electrodes to avoid short-circuiting (DC current passes between the wire leads instead of passing through the BDD anode).
Commercialization: AirLift currently provides services to treat contaminated groundwater. AirLift Environmental is modifying their existing patented commercial system (a Modular Oxidant Delivery System used to clean up groundwater plumes) to create a Modular Electrode Delivery System to treat PFAS-contaminated water and saturated soil in investigation derived waste (IDW). Upon completion of their Phase I research, AirLift has completed a PFAS IDW Treatment Kit that is ready for pilot testing in the field and the commercial market thereafter.
While AirLift's immediate focus is treating containerized wastes, AirLift also plans to incorporate electrochemical oxidation into its patented groundwater modular delivery system so that it can eventually be used in situ to treat PFAS-contaminated groundwater.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 2 publications | 2 publications in selected types | All 2 journal articles |
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Yanagida A, Webb E, Harris CE, Christenson M, Comfort S. Using Electrochemical Oxidation to Remove PFAS in Simulated Investigation-Derived Waste (IDW). Laboratory and Pilot-Scale Experiments. Water.2022;14(17):2708. |
68HERC20C0033 (Final) |
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McCarville B. Airlife Environmental's field research leads to innovative groundwater treatment methods. Midlands Business Journal2020;46(36):1. |
68HERC20C0033 (Final) |
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The 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.