POTSDAM -- Two researchers are getting $1 million from the U.S. Air Force to develop a method that cleans contaminated groundwater using an electric discharge of plasma.
Thomas Holsen and Selma Mededovic Thagard, faculty at Clarkson University’s Wallace H. Coulter School of Engineering, along with Stephen Richardson, principal engineer at GSI Environmental Inc., are working with rhe grant.
They have built a device called an enhanced contact electrical discharge plasma reactor, which contains metal electrodes that transmit electricity through a gaseous (argon) layer. The electricity flow forms a high-energy plasma at the electrode tips.
“The plasma acts like fire. When spread across the water surface, it destroys contaminants that linger at the interface of the gas and water,” Thagard said in a news release from the school. The reactor uses only electricity to create plasma. It requires no chemical addition and produces no waste.
The contaminants of interest are poly- and perfluoroalkyl substances (PFASs), a group of manmade chemicals used historically for a wide variety of residential, commercial and industrial purposes, including nonstick cookware, stain-resistant fabric and carpet, some food packaging and commercial and military firefighting foam. PFASs are of growing concern because of their persistence in the environment.
Measurements of groundwater at numerous military firefighting foam release sites reveal PFAS levels significantly higher than would be allowed in drinking water based on current health advisory levels. The most common approach for eliminating these contaminants from the water is to use granular activated carbon (GAC) filters. The downside of using this approach is that it only transfers PFAS from one medium (water) to another (GAC). One of the Air Force’s goals is to find a technology that completely destroys PFASs or at least breaks them down to compounds that are less toxic. The plasma reactor can potentially solve these problems.
The argon plasma in the reactor is responsible for creating a wide range of oxidative and reductive species. The reductive species destroy and break PFASs down into less toxic products that either remain in the water, or are released into the atmosphere as harmless gases.
The researchers also predict that their plasma technology will reduce cleaning costs by 50 to 80 percent.
Mededovic Thagard and Holsen are also working on modifying the system so that it can eliminate a wider range of contaminates in smaller volumes of water, thereby increasing efficiency and reducing costs even further.
“We are excited to be able to work with the Air Force to test our process at one of their sites,” Holsen said in the release. “With many sites containing PFASs needing remediation, we hope our process can be a game changer in terms of lower treatment costs and better treatment efficiency.”