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: 68HERC20C0008Title: 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: II
Project Period: November 1, 2019 through October 31, 2021 (Extended to October 31, 2022)
RFA: Small Business Innovation Research (SBIR) - Phase II (2019) Recipients Lists
Research Category: SBIR - Water Quality , Small Business Innovation Research (SBIR)
Description:
Manufacture and disposal of poly- and perfluoroalkyl substance (PFAS) containing-products including the historical use of aqueous film forming foam (AFFF) formulations containing PFAS 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. To help address this issue our SBIR Phase II work was aimed at developing a commercially viable plasma-based PFAS treatment system based on the generation of electrical discharge plasma, the most effective and efficient destructive technology available for degrading PFAS. The specific goal of the project was to increase the treatment capacity of the current plasma system that was optimized as part of our Phase I SBIR work from 2 to 10 gpm in an easily reproducible modular design. Expanded R&D activity performed under the Commercialization Option included the integration of our scaled-up 10 gpm system into a mobile trailer and its field demonstration.
Summary/Accomplishments (Outputs/Outcomes):
We have successfully developed a scale-up treatment system and integrated it into mobile treatment trailers that have been demonstrated at several field sites. For low concentration streams like contaminated groundwater the system consists of modular, flow-through enhanced contact (EC) reactors that hold approximately 100 gallons and contain baffles to direct the water flow on a circuitous path through the reactors. For high concentration streams the system consists of three reactors, a high concentration reactor, low concentration reactor and polishing reactor used in sequence. In both systems bubbles generated by diffusers at the bottom of the reactor chambers are used to transport the PFAS to the interface where plasma is being generated. The treatment system also contains a commercially viable plasma generating unit, The final component of the system is a gas recirculation pump and related components that was scaled-up to accommodate the larger gas flowrate needed for the system.
Conclusions:
DMAX Plasma has successfully developed a commercially viable mobile PFAS treatment system. The system is built around an enhanced contact (EC) plasma reactor that is effective at degrading PFAS in groundwater, in investigation derived waste (IDW) and concentrated waste streams like regenerable ion exchange still bottoms and membrane concentrate. In this reactor, PFAS compounds are transported to the (plasma) gas-liquid interphase using argon gas bubbles, where they are effectively degraded by plasma. Plasma produces numerous oxidative (e.g., OH, O, HO2, O2‒, O2, H2O2) and reductive species (e.g., free and aqueous electrons eaq-, H), of which the latter play a key role in degrading PFAS.
The EC plasma reactor system is one of the only PFAS destructive technologies that has been demonstrated in the field. It has repeatedly been shown to be effective at destroying a wide range of PFAS over a very broad concentration range, is easily and safely deployed, and requires a small amount of process energy. The plasma process can be effectively used in many locations within a PFAS treatment train, for example it can be used directly on aqueous streams as a destructive technology or after pre-concentration by IX resin or membrane processes. It can also be used upstream of other treatment technologies that would benefit from the removal of long-chain PFAS in particular. For example it could extend breakthrough times of short-chain PFAS compounds in sorptive technologies where the long-chain compounds can outcompete short-chain compounds for sorption sites.
There have been significant advancements in our plasma technology over the last several years and it is proven to be a very effective, robust technology for the destruction of PFAS compounds. With the addition of a surfactant, current configurations are most effective for PFAS compounds containing greater than four carbon atoms in their tails, although removal of even shorter compounds does occur but at a slower rate. Ongoing research is aimed at optimizing reactor conditions, exploring other surfactants to bring PFAS to the interface, and investigating other plasma reactor configurations for even higher capacity throughput.
SBIR Phase I:
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.