Effective Treatment of Trichloroethylene-Contaminated Soil by Hydrogen Peroxide in Soil Slurries

Trichloroethylene （TCE）, as one of the most common chlorinated organic compounds in soils and aquifers at many industrial sites, is carcinogenic and often recalcitrant in environment. TCE degradation in artificially contaminated soil samples was conducted using Fenton-like processes, i.e., by addition of excess hydrogen peroxide （H2O2）. H2O2 could directly oxidize TCE without addition of ferrous iron in contaminated soil. Under the optimal condition （H2O2 concentration of 300 mg kg^-1, pH at 5.0, and reaction time of 30 rain）, the removal efficiency of TCE in the soil was up to 92.3%. When the initial TCE concentration increased from 30 to 480 mg kg^-1 in soil, the TCE removal rates varied from 89.2% to 86.6%; while the residual TCE in soil ranged from 2.28 to 47.57 mg kg^-1. Results from successive oxidations showed that the TCE removal rate with the TCE concentration of 180 mg kg^-1 increased slightly from 91.6% to 96.2% as the number of successive oxidation cycle increased from one to four. Therefore, increasing the frequency of H2O2 oxidation was perhaps a feasible way to increase TCE removal rate for TCE-contaminated soil.