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Innovations
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TCETreatment Pasta-bilities W. Conard Holton Abstract
Monsanto's "Lasagna" process uses layers of treatment zones spaced between buried electrodes to remove trichloroethylene (TCE) from contaminated soil and groundwater. TCE is used primarily as a metal degreaser as well as in products such as dyes, printing ink, and paint. TCE can eventually make its way into the environment and is prevalent in the water and soil of industrialized nations. Although TCE breaks down in a few days when released into the atmosphere, it degrades much more slowly in soil, taking months or years. Moreover, it is often broken down by microbes into toxic substances such as vinylidene chloride (a suspected human carcinogen) and vinyl chloride (a known human carcinogen) . The Lasagna process is based on the principle of electro-osmosis, in which an electric current draws water from low-permeability soils such as clays, silts, and fine sands. To remove TCE from contaminated soils, Monsanto scientists added layers of filtering media, which attack the contaminant as it is pulled from electrode to electrode. The technology has been tested at the Paducah Gaseous Diffusion Plant in western Kentucky, where it removed over 98% of TCE from contaminated soil.
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