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: 5.32). 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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    • "where k OH , TOrCs is the second order rate constant for the reaction between OH and TOrCs ; and [ OH ] is the steady - state concentra - tion of OH radicals ( Wang et al . , 2012 ; Kim et al . , 2009 ; Lopez et al . , 2003 ; Tian et al . , 2014 ) ."
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    ABSTRACT: A combination of surrogate parameters and indicator compounds were measured to predict the removal efficiency of trace organic compounds (TOrCs) using low pressure (LP)-UV/H2O2 advanced oxidation process (AOP), engaged with online sensor-based monitoring system. Thirty-nine TOrCs were evaluated in two distinct secondary wastewater effluents in terms of estimated photochemical reactivity, as a function of the rate constants of UV direct photolysis (kUV) and hydroxyl radical (OH) oxidation (kOH). The selected eighteen TOrCs were classified into three groups that served as indicator compounds: Group 1 for photo-susceptible TOrCs but with minor degradation by OH oxidation (diclofenac, fluoxetine, iohexol, iopamidol, iopromide, simazine and sulfamethoxazole); Group 2 for TOrCs susceptible to both direct photolysis and OH oxidation (benzotriazole, diphenhydramine, ibuprofen, naproxen and sucralose); and Group 3 for photo-resistant TOrCs showing dominant degradation by OH oxidation (atenolol, carbamazepine, DEET, gemfibrozil, primidone and trimethoprim). The results indicate that TOC (optical-based measurement), UVA254 or UVT254 (UV absorbance or transmittance at 254 nm), and total fluorescence can all be used as suitable on-line organic surrogate parameters to predict the attenuation of TOrCs. Furthermore, the automated real-time monitoring via on-line surrogate sensors and equipped with the developed degradation profiles between sensor response and a group of TOrCs removal can provide a diagnostic tool for process control during advanced treatment of reclaimed waters. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Water Research 09/2015; 81. DOI:10.1016/j.watres.2015.05.064 · 5.32 Impact Factor
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    • "TCE, due to its carcinogenic effect to humans, poses a potential health hazard for liver, immune system, male reproductive system, kidney, central nervous system, and developing embryo/fetus (Chiu et al. 2013). Advanced oxidation processes are widely used for the treatment of these chlorinated compounds because these are considered to be fast and cost-effective compared with conventional treatment processes due to pumpand-treat and bioremediation (Andreozzi et al. 1999; Ko et al. 2012; Wang et al. 2012). Hydroxyl radicals (@BULLETOH) were widely employed to treat the water contaminants, but persulfate (PS) recently has gained considerable attention among these oxidation reduction processes (Gao et al. 2012; Liang et al. 2008a). "
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    • "except at pH 6.5 where UV/chlorine led to more THMs than UV/H 2 O 2 (increased by 90–110%, compared to the controls). Previous modeling by the authors suggests that UV/chlorine at pH 6.5 is more effective at producing @BULLETOH than UV/H 2 O 2 in a similar water matrix at that pH (Wang et al., 2012). "
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