IN-SITU CHEMICAL OXIDATION OF TRICHLOROETHYLENE USING HYDROGEN-PEROXIDE

Laboratory studies were conducted to determine the feasibility of injecting and mixing hydrogen peroxide (H2O2) solutions into clay soils contaminated with trichloroethylene (TCE) to achieve in-situ chemical oxidation. Bench-scale slurry studies were conducted first using 0.3 L slurry reactors and TCE concentrations in the 1.9 to 34 mg/kg range. TCE reductions as high as 98% of the initial concentration were achieved with a H2O2 dose of 28 g H2O2/kg soil. TCE degradation increased with increasing hydrogen peroxide strength and appeared independent of the initial TCE concentration. Column studies were conducted with an apparatus fabricated to simulate in-situ mixing and chemical oxidant injection. Stainless steel columns 20 cm in diameter and 23 cm long, which were packed with clay soil, were mixed with an auger blade while H2O2 solutions were injected through orifices at the back of the mixing blade. The H2O2 doses for the column studies were 1.2 and 2.5 g H2O2/kg soil, based on an injection concentration of 5% weight H2O2 at volumetric additions of 5% and 10% of the soil volume treated. TCE reductions of 88% and 75% were achieved at the two dosing rates. Based on the results of these laboratory studies, in-situ chemical oxidation of contaminated soils appears to be a viable soil remediation technique that is dependent on the efficient delivery and distribution of H2O2 throughout the region to be treated.