Grantee Research Project Results
Final Report: An Enhanced Contact Plasma Reactor: A Competitive Remediation Technology for Per- and Perfluoroalkyl Substance (PFAS) Contaminated Water
EPA Contract Number: 68HE0D18C0022Title: An Enhanced Contact Plasma Reactor: A Competitive Remediation Technology for Per- and Perfluoroalkyl Substance (PFAS) Contaminated Water
Investigators: Multari, Nicholas
Small Business: DMAX Plasma LLC
EPA Contact: Richards, April
Phase: I
Project Period: October 1, 2018 through March 31, 2019
Project Amount: $98,991
RFA: Small Business Innovation Research (SBIR) - Phase I (2018) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Water , SBIR - Water Quality
Description:
Per- and Polyfluoroalkyl substances (PFAS) have received considerable attention due to their toxicity, ubiquitous presence and recalcitrance. Manufacture and disposal of PFAS-containing products has resulted in PFAS contamination of numerous water supplies. Recent reports indicate the Air Force alone is expecting to spend > $2.25 billion for cleanup for PFAS-contaminated sites. Thus, there is a huge market for technologies that can help remediate sites contaminated by PFAS. DMAX Plasma technology called an enhanced contact electrical discharge plasma reactor generates aqueous electrons which chemically reduce PFAS. Recent experiments on PFAS-impacted groundwater from a Department of Defense site demonstrated that the technology is capable of reducing perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) concentrations to below regulatory limits within minutes of treatment at 1 gallon per minute flowrate. These removal rates are significantly better than those of leading alternative treatment technologies and treatment costs are significantly lower. This proposal is aimed at eliminating the final hurdles towards a commercially viable reactor: improving the design of the plasma producing electrical circuit so it can operate more efficiently and continuously with minimum downtime. The project had three objectives:
(1) Improving the components and design of the spark gap so it can operate continuously with minimum downtime, as the spark gap is the first location in the circuit where plasma is generated,
(2) Shielding and optimally arranging the components of the electrical circuit so they are efficient in terms of space usage and energy consumption and do not impact nearby electrical equipment, and
(3) Determining the relationship between the solution electrical conductivity and the PFAS removal rate as a function of the applied voltage, discharge frequency, capacitance, and treatment time.
Summary/Accomplishments (Outputs/Outcomes):
This project met all three objectives outlined above.
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Improvements in the construction of the spark gap included: (i) incorporating and optimally spacing tungsten spheres and copper-tungsten rods into the spark gap box and (ii) spark gap operation in air without a need to pressurize the box.
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The spark gap has been enclosed in an electromagnetic noise-dampening box made of stainless steel and aluminum. The box, which also houses the plasma reactor(s), effectively absorbs the sound generated by the operation of the spark gap and reactor and provides shielding. Properly ratedhigh voltage cables, conduits, junction boxes, and connectors have been incorporated and individual components optimally spaced and tested over multiple hours of operation.
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The removal rate of PFOS was higher than that of PFOA, regardless of the solution conductivity or discharge frequency. The concentrations of both compounds were removed to below regulatory limits within minutes. Despite the complex dependence of the PFOA and PFOS removal rates on discharge frequency, capacitance, applied voltage and solution conductivity, the circuit operational parameters for achieving maximum removal rates for both compounds have been determined.
We have also successfully tested a modification of the proposed external plasma-generating circuit to include a stationary (i.e., non-rotating) spark gap and an alternating current (AC) capacitor-charging power supply with the purpose of lowering the equipment and operating costs. The modified AC-stationary spark gap charging circuit achieved the same removal rates of PFOA and PFOS as the originally proposed DC-rotating spark gap charging circuit and with the same energy efficiency. The new circuit design is not only simpler but also more economical. In addition, the new circuit will be much more reliable and require much less maintenance since there are no moving parts. As a result, this novel circuit design will replace the rotating spark gap and the DC charging power supply in the final commercial plasma reactor treatment system.
Conclusions:
Plasma-based treatment is a viable technology for the treatment of PFAS-contaminated water. Both PFOA and PFOS are removed at time scales and energy efficiency that are superior to those of other destructive technologies. The removal rates of both PFOA and PFOS can be and were maximized by optimizing the plasma applied voltage, capacitance and discharge frequency. The plasma-generating external electrical circuit has been modified for simplicity and cost. A design for the electrical circuit scale up alongside the plasma reactor scale up has been developed.
Commercialization:
The enhanced contact electrical discharge plasma reactor has been successfully demonstrated on a bench scale and critical hurdles towards a commercially viable reactor eliminated. DMAX Plasma LLC's core business will be to supply plasma reactors to treat PFAS-contaminated water to bring concentrations under regulatory limits. Two different market segment points of application are envisioned for the technology: (1) On-Site Remediation / Cleanup that focuses on addressing the problem at the point of origin (point source contamination) and (2) Point of Use that focuses on addressing the problem at the point of use. These markets are currently being served by a multitude of engineering firms and DMAX Plasma will seek to partner with industry leaders to implement this technology, making use of their network of existing and potential customers. As the next step in gaining market acceptance, we have two pilot project demonstrations scheduled with our environmental consulting partners for this year.
DMAX Plasma will promote its solution by participating in industry conferences as well as by publishing results in peer-reviewed journals. DMAX Plasma will also work with its environmental engineering partners to perform additional case studies and publish case study results in environmental engineering and drinking water treatment publications. As our technology gains acceptance, we envision initial sales to be on a project basis, delivered through partner organizations that are environmental consulting firms. We aim to have a design and implementation focus, procuring off-the-shelf and custom-made components through downstream suppliers and working directly with engineering firms to specify, install, and maintain the systems at contaminated sites.
SBIR Phase II:
An Enhanced Contact Plasma Reactor: A Competitive Remediation Technology for Per- and Perfluoroalkyl Substance (PFAS) Contaminated Water | 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.