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


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.

Download full-text


Available from: James R Bolton,
211 Reads
    • "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 ) ."
    [Show abstract] [Hide abstract]
    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 · 5.53 Impact Factor
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Graphene oxide (GO) and nano-sized zero-valent iron-reduced graphene oxide (nZVI-rGO) composite were prepared. The GO and nZVI-rGO composite were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. The size of nZVI was about 6 nm as observed by TEM. The system of nZVI-rGO and persulfate (PS) was used for the degradation of trichloroethylene (TCE) in water, and showed 26.5 % more efficiency as compared to nZVI/PS system. The different parameters were studied to determine the efficiency of nZVI-rGO to activate the PS system for the TCE degradation. By increasing the PS amount, TCE removal was also improved while no obvious effect was observed by varying the catalyst loading. Degradation was decreased as the TCE initial concentration was increased from 20 to 100 mg/L. Moreover, when initial solution pH was increased, efficiency deteriorated to 80 %. Bicarbonate showed more negative effect on TCE removal among the solution matrix. To better understand the effects of radical species in the system, the scavenger tests were performed. The •SO4 (-) and •O2 (-) were predominant species responsible for TCE removal. The nZVI-rGO-activated PS process shows potential applications in remediation of highly toxic organic contaminants such as TCE present in the groundwater. Graphical abstract Persulfate activated by reduced graphene oxide and nano-sized zero-valent iron composite can be used for efficient degradation of trichloroethylene (TCE) in water.
    Environmental Science and Pollution Research 07/2015; DOI:10.1007/s11356-015-5034-1 · 2.83 Impact Factor
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Disinfection by-product (DBP) formation may be a concern when applying ultraviolet light and free chlorine (UV/chlorine) as an advanced oxidation process (AOP) for drinking water treatment, due to typically large chlorine doses (e.g. 5-10mgL(-1) as free chlorine). A potential mitigating factor is the low chlorine contact times for this AOP treatment (e.g. seconds). Full-scale and pilot-scale test results showed minimal trihalomethane (THM) and haloacetic acid (HAA) formation during UV/chlorine treatment, while dichloroacetonitrile (DCAN) and bromochloroacetonitrile (BCAN) were produced rapidly. Adsorbable organic halide (AOX) formation was significant when applying the UV/chlorine process in water that had not been previously chlorinated, while little additional formation was observed in prechlorinated water. Chlorine photolysis led to chlorate and bromate formation, equivalent to approximately 2-17% and 0.01-0.05% of the photolyzed chlorine, respectively. No perchlorate or chlorite formation was observed. During simulated secondary disinfection of AOP-treated water, DBP formation potential for THMs, HAAs, HANs, and AOX was observed to increase approximately to the same extent as was observed for pretreatment using the more common AOP of UV combined with hydrogen peroxide (UV/H2O2). Copyright © 2015 Elsevier B.V. All rights reserved.
    Science of The Total Environment 03/2015; 518-519:49-57. DOI:10.1016/j.scitotenv.2015.02.094 · 4.10 Impact Factor
Show more