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.
Highlights
The presence of organic pollutants in the subsurface indicates a serious threat to groundwater sources and has gained considerable attention over the last two decades (Sabatini et al, 1994; Ponza et al, 2010)
Samples were analyzed with a Varian CP–3800 (Australia) gas chromatograph (GC), equipped with flame ionization detector (FID)
Ion chromatography (Metrohm 883 basic IC equipped with ion separation and conductivity detector, 1.7 mM NHCO3 and 1.8 mM Na3CO3 as eleunts) and an Agilent 1100 HPLC/UV system, were used to detection of potential intermediates formed during process
Summary
The presence of organic pollutants in the subsurface indicates a serious threat to groundwater sources and has gained considerable attention over the last two decades (Sabatini et al, 1994; Ponza et al, 2010). Trichloroethylene (TCE) is possibly a carcinogenic compound to human and is one of the most common contaminant in groundwater. Due to its serious health effects, U.S Environmental Protection Agency (EPA) has set the maximum contaminant level (MCL) and maximum contaminant level goal (MCLG) for TCE as 0.005 mg L-1 and zero, respectively. Treatment technologies such as adsorption by activated carbon and air stripping are effective in removing TCE from contaminated waters, but these processes.
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