Article

Medium pressure UV combined with chlorine advanced oxidation for trichloroethylene destruction in a model water

Department of Civil Engineering, University of Toronto, 35 St. George St., Toronto, Ontario M5S 1A4, Canada.
Water Research (Impact Factor: 5.53). 06/2012; 46(15):4677-86. DOI: 10.1016/j.watres.2012.06.007
Source: PubMed

ABSTRACT

The effectiveness of ultraviolet (UV) combined with chlorine as a novel advanced oxidation process (AOP) for drinking water treatment was evaluated in a bench scale study by comparing the rate of trichloroethylene (TCE) decay when using UV/chlorine to the rates of decay by UV alone and UV/hydrogen peroxide (H₂O₂) at various pH values. A medium pressure mercury UV lamp was used. The UV/chlorine process was more efficient than the UV/H₂O₂ process at pH 5, but in the neutral and alkaline pH range, the UV/H₂O₂ process became more efficient. The pH effect was probably controlled by the increasing concentration of OCl⁻ at higher pH values. A mechanistic kinetic model of the UV/chlorine treatment of TCE showed good agreement with the experimental data.

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    • "In the combined UV/chlorine process, absorption of UV photons causes the free chlorine species (i.e., HOCl and OCl À ) to generate several radicals such as OH and Cl. Meanwhile, HOCl and OCl À can also react with OH with reaction rate constants of 8.46 Â 10 4 and 9.0 Â 10 9 M À1 s À1 , respectively (Wang et al., 2012). "
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    • "Wang et al. [15] reported that HOCl and OCl − could efficiently absorb UV light 2.3 and 10.7 times more than H 2 O 2 as irradiated by medium pressure UV lamps under equal molar conditions. But the quantum yields of @BULLETOH were 0.46 and 0.28 for HOCl and OCl − , respectively, which were much lower than 0.85 of UV/H 2 O 2 process [16] [17]. "
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    • "To minimize exposure of humans and aquatic ecosystems to wastewater-derived chemical contaminants, advanced oxidation processes (AOPs) have been employed to attenuate these contaminants that are not readily oxidized during conventional treatment (Wang et al., 2012; Wols and Hofman-Caris, 2012). Ultraviolet (UV)based AOPs are becoming increasingly popular in potable reuse applications , along with ozonation and reverse osmosis membrane filtration (Gerrity et al., 2012). "
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