New Technologies for the Remediation of Halogenated Organics

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The "Halogenated Organics" project is proposing three Study Areas, each of which is related to the central theme of treating contaminated soil vapor and ground water with an emphasis on destruction of the target pollutant, rather than capture and disposal. We will focus mainly, although not exclusively, on methods for the destruction of perchloroethylene (PCE) and trichloroethylene (TCE), which have been the subject of extensive study in our laboratories, and which dominate the list of VOC contaminants at the nearby Park-Euclid State Superfund site, where we have worked for the past four years. This work is motivated by difficulties associated with destruction or final disposal of chlorinated solvents that are traditionally recovered from contaminated sites via pump-and-treat or soil-vapor-extraction (SVE) methods, which, in themselves, merely transfer contaminants from one medium to another. For example, when activated carbon absorption units become loaded with PCE the spent carbon itself becomes a hazardous waste and must be handled as such. Subsequent high-temperature incineration of the carbon may produce much more toxic contaminants such as dioxins and furans whose release to the atmosphere might pose an even greater health risk. With this in mind, the three Study Areas focus on chemically reducing or oxidizing gaseous or aqueous chlorinated organics using catalytic thermochemical or electrochemical techniques: 1) Catalyzed thermochemical destruction of gas phase VOCs, 2) electrolysis by advanced aqueous-phase and novel three-phase electrochemical reactors, and 3) fuel-cells for gas-phase contaminants. Each of the Study Areas will yield effluent streams with unknown, but hopefully lower, toxicity. In all cases, we intend capturing the effluent, even if it appears clean by chemical analysis (GC/ECD, FID, or MS), and subjecting it to toxicological analysis in the Biological Response Section of the Hazard Identification Core. Since all out pilot-scale work will continue to be done at the Park-Euclid field site there is a strong, and pervasive link to the Research Translation Core. This work is responsive to the call from a 1997 National Academies blue ribbon panel for the development of new destructive treatment technologies to help clean up the nation's long list of Superfund sites.