Soil heating for remediation of dissolved trichloroethylene in low-permeable soil

Electrical heating of a low-permeable silt layer contaminated with dissolved trichloroethylene (TCE) was simulated in a laboratory tank. Heating to 85 and 100 degrees C led to dramatically increased mass fluxes in the soil vapor extraction system used for capture of the effluent. Within 45 days, soil concentrations were reduced by 99.8%, without significant reduction in the soil moisture content. This study showed that thermal techniques are not only efficient in removing liquid contaminants, also dissolved and adsorbed contaminants are removed rapidly due to in-situ steaming, dramatic increases in the volatility at higher temperatures, and reduced sorption coefficients. Clean-up criteria for groundwater and soil concentrations can be met by ensuring good hydraulic control and capture of all the evolved gases. Thermal In-situ treatment appears economically attractive, since treatment times are in the order of months, low residual contaminant levels can be achieved, and the energy consumption is not cost-prohibitive.