Abstract

Trichloroethylene (TCE) is a common pollutant in groundwater and one of the priority pollutants listed by the U.S. EPA. With regard to concentration ranges in previous studies exceeding environmental levels by far with millimolar concentrations of TCE, this study deals with the degradation of TCE at micromolar concentrations by UV/H₂O₂. The degradation rate of TCE at different dilute solution levels, 30, 300 and 3000 mg L^-1 (0.22, 2.28 and 22.83 micromolar) at different initial pHs was examined. In addition, samples were taken from four contaminated wells to measure the degradation rate of TCE. It was shown that the degradation rate of TCE increased due to the reduction of initial concentration in both aqueous solution and groundwater samples. The TCE degradation constants in groundwater samples increased by a factor of 2.05, while the initial concentration reduced from 1345.7 to 97.7 µg1 L^-1. By increasing the molar ratios of H₂O₂ to TCE from 13 to 129, caused the degradation rates to increase in aqueous solutions. No harmful byproducts such as haloacetic acids (HAAs) were detected at these low levels of initial concentration of TCE during process. This study confirmed that application of UV/H₂O₂ process could be an effective method in treating contaminated groundwater by TCE at low concentrations.

Key words:  Trichloroethylene, UV-radiation, UV/H₂O₂ process, groundwater remediation.