Plasma Technology For Cold Cleanups

June 10, 1996


LOS ALAMOS, N.M., June 10, 1996 - Los Alamos National Laboratory scientists have successfully demonstrated at two Air Force bases a novel cleanup technology that efficiently destroys a number of organic contaminants and shows commercial promise.

The new system destroyed volatile organic compounds extracted from soil at McClellan Air Force Base, Calif., and from ground water at Tinker Air Force Base, Okla., using a nonthermal plasma that creates highly reactive molecules called free radicals to break down the contaminants.

The plasma technology is likened to cold combustion; instead of using heat to break up contaminants, the plasma cells destroy molecules using highly reactive free radicals - atoms or molecules that have unpaired electrons.

McClellan and Tinker Air Force Base officials were looking for innovative technologies to treat legacy waste problems. McClellan searched for technologies to treat VOCs from a 40-year-old hazardous waste disposal site and recruited two subcontractors to demonstrate new remediation methods under industrial conditions.

VOCs are common contaminants that come from paints, thinners, cleaning solvents and industrial fuels. The contaminants include benzene, tolulene, acetone, freon, xylene, trichloroethelyne, trichloroethane and perchloroethylene, some of which react in the atmosphere and contribute to the depletion of high-altitude ozone, the formation of ground-level ozone and, to a lesser extent, acid rain.

Conventional waste treatment methods such as incineration or carbon filtration create secondary waste streams that are often as difficult to treat as the original contamination, according to researchers.

An environmental contractor for McClellan vacuum extracted the compounds from the ground and directed a portion of the vapor-laden air stream to the different technologies being tested, including the 20-kilowatt plasma system that Los Alamos researchers and the industrial partner, High Mesa Technologies located in Santa Fe, N.M., delivered to the site.

The Los Alamos technology treated a maximum of 10 cubic feet of air per minute and operated for 300 hours over a two-month period. Researchers monitored gas flows, temperature, pressures and electrical power and stored the data on a computer.

The degree of destruction reached 99.9 percent for TCE and nearly 98 percent for PCE, and averaged nearly 95 percent for all other VOCs.

After using the technology at McClellan, High Mesa Technologies is planning to build a larger model and commercialize the system.

At Tinker Air Force Base, ground water was pumped through an air stripper that cascades the water within the stripping tower causing the highly evaporative contaminants to become airborne. The Los Alamos technology treated the airborne compounds to demonstrate that the system works even on low-level contaminants.

Researchers pumped the air that came off the water stripper through the plasma cells, where it is treated. Clean air exits the system, while the leftover, less-hazardous compounds are recovered in small, stainless steel tanks that contain a dry scrubber material. The preliminary results from Tinker indicate destruction fractions of up to 99.9 percent.

The new portable plasma system consists of a 20-foot trailer filled with specialized equipment. The chemical reactions occur in an aluminum tank that houses 20 non-thermal plasma cells. The non-thermal plasma cells use high voltage electrical energy to create large quantities of highly reactive free radicals. The free radicals subsequently react with and break up hazardous organic chemicals, converting them to non-hazardous substances such as carbon dioxide, water, and acids that can be neutralized. Most of the free radicals are oxygen atoms and hydroxyl molecules that react with and oxidize the larger molecules, thereby functioning much the same as incineration, but without the heat and added fuel exhaust.

Los Alamos is developing the nonthermal plasma air pollution control equipment together with the Electric Power Research Institute and High Mesa Technologies. EPRI is the research and development arm of the electric power industry based in Palo Alto, Calif.

Los Alamos National Laboratory is operated by the University of California for the Department of Energy.

Contact Information:
Kathy DeLucas
Los Alamos Nat'l Laboratory
Public Affairs, Media Relations
MS C177
Los Alamos, NM 87545
(505) 665-9201
Fax: 665-3910

DOE/Los Alamos National Laboratory

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