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HORIZONTAL LASAGNA TO BIOREMEDIATE TCE
Citation:
DavisHoover*, W J., M H. Roulier*, T. Bryndzia, L. C. Murdoch, M Kemper*, AND et al. HORIZONTAL LASAGNA TO BIOREMEDIATE TCE. 2nd Symposium; Heavy Metals in the Environment and Electromigration Applied to Soil Remediation, Lyngby, Denmark, 7/7-9/1999.
Description:
Removal of TCE from these tight clay soils has been technically difficult and expensive. However, the LASAGNATM technique allows movement of the TCE into treatment zones for biodegradation or dechlorination in place, lessening the costs and exposure to TCE. Electroosmosis was conducted between an anode of titanium mesh placed upon the ground surface and a cathode composed of a horizontal graphite-gilled fracture created at a depth of 4 m below the ground surface. Liquids were also pumped out of the cathode to maintain a downward hydraulic head gradient and liquid flow. Two types of remediation zones between the electrodes were created by horizontal fracturing methods, this paper will discuss the bioremediation treatment zone.
For bioremediation of the TCE, a single fracture consisting of granular activated carbon (GAC) inoculated with a consortium of methanotrophic TCE degrading soil bacteria was created by hydraulic fracture between the electrodes within the contaminated clay material at 240 cm depth. After 116 days of electroosmosis to transport TCE into the remediation zone, biodegradation within the zone was stimulated for 70 days by the continuous injection of 3 % methane in air into the treatment zone. Then both electroosmosis and methanotrophic biodegradation were practiced simultaneously. Between January 15, 1997 and November 23, 1998, the concentration of TCE in the Biocell soil was reduced to a median of zero ppm. During the same time period, in the untreated natural attenuation area, little change in TCE concentration was observed.