Characterization of disinfection byproduct formation and associated changes to dissolved organic matter during solar photolysis of free available chlorine

WATER RESEARCH

卷:146

Article

Young, Tessora R.¹  Li, Wentao²  Guo, Alan¹  Korshin, Gregory V.¹  Dodd, Michael C.¹ 

[1] Univ Washington, Dept Civil & Environm Engn, Seattle, WA 98195 USA

[2] Nanjing Univ, Sch Environm, State Key Lab Pollut Control & Resources Reuse, Nanjing 210023, Jiangsu, Peoples R China

关键词: Chlorine;    Solar irradiation;    Ozone;    Hydroxyl radical;    Disinfection byproducts;    Dissolved organic matter;   

DOI  :  10.1016/j.watres.2018.09.022

来源: Elsevier

【 摘 要 】

Solar irradiation of chlorine-containing waters enhances inactivation of chlorine-resistant pathogens (e.g., Cryptosporidium oocysts), through in situ formation of ozone, hydroxyl radical, and other reactive species during photolysis of free available chlorine (FAC) at UVB-UVA wavelengths of solar light (290-400 nm). However, corresponding effects on regulated disinfection byproduct (DBP) formation and associated dissolved organic matter (DOM) properties remain unclear. In this work, when compared to dark chlorination, sunlight-driven FAC photolysis over a range of conditions was found to yield higher DBP levels, depletion of DOM chromophores and fluorophores, preferential removal of phenolic groups versus carboxylic acid groups, and degradation of larger humic substances to smaller molecular weight compounds. Control experiments showed that increased DBP levels were not due to direct DOM photolysis and subsequent dark reactions with FAC, but to co-exposure of DOM to FAC and reactive species (e.g., O-3, HO center dot, Cl-center dot, Cl-2(center dot-), ClO center dot) generated by FAC photolysis. Because solar chlorine photolysis can enable inactivation of chlorine-resistant pathogens at far lower CTFAC values than chlorination alone, the increases in DBP formation inherent to this approach can likely be offset to some extent by the ability to operate at significantly decreased CTFAC. Nonetheless, these findings demonstrate that applications of solar chlorine photolysis will require careful attention to potential impacts on DBP formation. (C) 2018 Elsevier Ltd. All rights reserved.

【 授权许可】

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