In-Situ Chemical Oxidation of Trichloroethylene Using Hydrogen Peroxide

Abstract

Laboratory studies were conducted to determine the feasibility of injecting and mixing hydrogen peroxide (H ₂ O ₂ ) 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 H ₂ O ₂ dose of 28 g H ₂ O ₂ /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 H ₂ O ₂ solutions were injected through orifices at the back of the mixing blade. The H ₂ O ₂ doses for the column studies were 1.2 and 2.5 g H ₂ O ₂ /kg soil, based on an injection concentration of 5% weight H ₂ O ₂ 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 H ₂ O ₂ throughout the region to be treated.