IN-SITU CHEMICAL OXIDATION OF TRICHLOROETHYLENE USING HYDROGEN-PEROXIDE

Laboratory studies were conducted to determine the feasibility of inje cting and mixing hydrogen peroxide (H2O2) solutions into clay soils co ntaminated with trichloroethylene (TCE) to achieve in-situ chemical ox idation. Bench-scale slurry studies were conducted first using 0.3 L s lurry reactors and TCE concentrations in the 1.9 to 34 mg/kg range. TC E 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 appa ratus fabricated to simulate in-situ mixing and chemical oxidant injec tion. 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 bla de. The H2O2 doses for the column studies were 1.2 and 2.5 g H2O2/kg s oil, based on an injection concentration of 5% weight H2O2 at volumetr ic 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 res ults of these laboratory studies, in-situ chemical oxidation of contam inated soils appears to be a viable soil remediation technique that is dependent on the efficient delivery and distribution of H2O2 througho ut the region to be treated.