Efficiency of pre-oxidation of natural organic matter for the mitigation of disinfection byproducts: Electron donating capacity and UV absorbance as surrogate parameters

WATER RESEARCH

卷:187

Article

Rouge, Valentin^1,2  von Gunten, Urs^3,4,5  Allard, Sebastien¹ 

[1] Curtin Univ, Dept Chem, Curtin Water Qual Res Ctr, GPO Box U1987, Perth, WA 6845, Australia

[2] Gwangju Inst Sci & Technol GIST, Sch Earth Sci & Environm Engn, Gwangju 61005, South Korea

[3] Eawag, Swiss Fed Inst Aquat Sci & Technol, CH-8600 Dubendorf, Switzerland

[4] Ecole Polytech Fed Lausanne EPFL, Sch Architecture Civil & Environm Engn ENAC, CH-1015 Lausanne, Switzerland

[5] Swiss Fed Inst Technol, Swiss Fed Inst Technol, Inst Biogeochem & Pollutant Dynam IBP, Dept Environm Syst D USYS, Univ Str 16, CH-8092 Zurich, Switzerland

关键词: Electron donating capacity (EDC);    Chemical pre-oxidation;    Natural organic matter (NOM);    Disinfection byproduct (DBP);    UV absorbance (UV254);    Chlorine disinfection;   

DOI  :  10.1016/j.watres.2020.116418

来源: Elsevier

【 摘 要 】

Pre-oxidation is often used before disinfection with chlorine to decrease the reactivity of the water matrix and mitigate the formation of regulated disinfection byproducts (DBPs). This study provides insights on the impact of oxidative pre-treatment with chlorine dioxide (ClO2), ozone (O-3), ferrate (Fe(VI)) and permanganate (Mn(VII)) on Suwannee River Natural Organic Matter (SRNOM) properties characterized by the UV absorbance at 254 nm (UV254) and the electron donating capacity (EDC). Changes in NOM reactivity and abatement of DBP precursors are also assessed. The impact of pre-oxidants (based on molar concentration) on UV254 abatement ranked in the order O-3 > Mn(VII) > Fe(VI)/ClO2, while the efficiency of pre-oxidation on EDC abatement followed the order Mn(VII) > ClO2 > Fe(VI) > O-3 and two phases were observed. At low specific ClO2, Fe(VI) and Mn(VII) doses corresponding to < 50% EDC abatement, a limited relative abatement of UV254 compared to the EDC was observed (similar to 8% EDC abatement per 1% UV254 abatement). This suggests the oxidation of phenolic-type moieties to quinone-type moieties which absorb UV254 and don't contribute to EDC. At higher oxidant doses (> 50% EDC abatement), a similar abatement of EDC and UV254 (similar to 0.9-1.2% EDC abatement per 1% UV254 abatement) suggested aromatic ring cleavage. In comparison to the other oxidants, O-3 abated the relative UV254 more effectively, due to a more efficient cleavage of aromatic rings. For a pre-oxidation with Mn(VII), ClO2 and Fe(VI), similar correlations between the EDC abatement and the chlorine demand or the adsorbable organic halide (AOX) formation were obtained. In contrast, O-3 pre-treatment led to a lower chlorine demand and AOX formation for equivalent EDC abatement. For all oxidants, trihalomethane formation was poorly correlated with both EDC and UV254. The EDC abatement was found to be a pre-oxidant-independent surrogate for haloacetonitrile formation. These results emphasize the benefits of combining EDC and UV254 measurement to understand and monitor oxidant-induced changes of NOM and assessing DBP formation. (C) 2020 Elsevier Ltd. All rights reserved.

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