DOI: 10.5176/2251-189X_SEES13.26

Authors: Han-Sol Kim, Si-Hyun Do, Young-Hoon Jo, Sung-Ho Kong

Abstract:

A treatment process, which was a series of two continuous stirred-tank reactors (CSTRs), was evaluated for the clean-up of mixed chlorinated compounds (i.e. tetrachloroethylene (PCE), trichloroethylene (TCE), carbon tetrachloride (CT) and chloroform (CF)) in groundwater. The first reactor was designed to perform oxidation derived by persulfate (PS) activated with UV radiation (UV/PS), and the second reactor was for reduction, which was the mixing of effluents from the first reactor and the additional injection of ethanol at the presence of UV radiation. Concentrations of each contaminant (i.e. PCE, TCE, CT and CF) in groundwater from the actual contaminated site were 1, 2.4, 0.4 and 1 mg/L,
respectively. The results showed that degradation efficiencies in 1st reactor (i.e. UV/PS system) were 99{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} for PCE, 99{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} for TCE, 43{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} for CT, and 59{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} for CF, respectively indicating PCE and TCE were effectively degraded. This also means possible dominant reactive species in 1st reactor could be sulfate radicals possibly with hydroxyl radicals. In 2nd reactor, CT was dramatically degraded, suggesting that organic radicals including superoxide anion were
produced. Through this process, the level of contaminants in effluent was satisfied the drinking water regulation in Korea (i.e. PCE 0.01mg/L, TCE 0.03mg/L, CT 0.04mg/L, and CF 0.8mg/L). Presently, modification of the process is evaluated to obtain not only treatability for higher contaminant concentrations but also economically effective conditions.

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