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TRANSPORT OF TRICHLOROETHYLENE (TCE) IN NATURAL SOIL BY ELECTROOSMOSIS
Citation:
AlAbed*, S R. AND J. L. Chen**. TRANSPORT OF TRICHLOROETHYLENE (TCE) IN NATURAL SOIL BY ELECTROOSMOSIS. Chapter 5, Smith and Burns (ed.), Physiochemical Groundwater Remediation. Kluwer Academic/Plenum Publishers, New York, NY, (2001).
Description:
Contamination in low permeability soils poses a significant technical challenge to in-situ remediation, primarily due to low mobilization of the contaminants and difficulty in uniform delivery of treatment reagents. An alternative approach using electroosmosis (EO) is used to mobilize Trichloroethylene (TCE) in soil. However, the EO approach causes significant chemical changes in the soil which may affect transport and/or chemical transformation of TCE. Laboratory experiments and mathematical modeling were used to characterize the transport and chemical transformation of TCE in undisturbed soil cores during EO. A contamination zone (CZ) were located 1 cm below the anode. Electroosmotic fluid flow was vertically downwards from anode to cathode. A voltage gradient of 1.4 V/cm was applied to the soil for 4 weeks. More than 95% of the TCE was mobilized toward the cathode in the soil over a period of 672 hrs. The advective velocity of TCE was approximately 1.3x10(-5) cm/sec and the dispersion coefficient is two times the diffusion coefficient of 6.9x10(-6) cm2/sec. We observed dichloroethylene (cis-1,2-DCE) indicating dechlorination of TCE. Dechlorination occurred in parts of the soil column where reducing conditions (Eh-pH conditions) are dominant. The most significant reductive dechlorination of TCE occurred near the cathode, a source of elecrons during electroosmosis. Results show the need to include a decay term in the transport equations. The results show that potential chemical transformation of chlorinated organic compounds cold enhance the remediation efficiency during EO.