Abstract：
In this study, the photodegradation of 33 different DBPs (trihalomethanes, haloacetic acids, haloacetaldehydes, and haloacetonitriles) and TOX with low pressure UV light and the subsequent reformation of DBPs with chlorine and monochloramine were investigated. Results indicated that photodegradation followed the order of TOI > TOBr > TOCl, and treated surface water with low SUVA254 background did not impact the photodegradation of highly UV susceptible DBPs such as triiodomethane (TIM), diiodobromomethane (DIBM), tribromomethane (TBM). The mass balance results of chloride, bromide and iodide showed that the main photodegradation mechanism of TOBr and TOI was dehalogenation supported by halide releases (i.e., Cl-, Br- and/or I- ion). In addition, the photodegradation removal effect was higher, when brominated DBPs formation was high. Although low pressure UV light effectively removed halogenated organic DBPs, subsequent use of disinfectants (Cl2 and NH2Cl) reformed photodegraded DBPs, and the overall DBPs concentrations were increased, which suggested that the released Br- and I- ions will reform DBPs in distribution systems, with oxidants present or added (e.g., booster chlorination) in distribution systems. This study showed that although UV photodegradation will reduce halogenated organic DBPs in distribution systems, especially more toxic iodinated and brominated DBPs, it will be a more effective technology towards the end of the distribution system or a point of entry solution rather than in distribution system with post-disinfection and residence time.
摘要：
在这项研究中,33种不同的DBPs(三卤甲烷，卤代乙酸,卤代乙醛，和卤代乙腈）和TOX在低压紫外线下，以及随后用氯和一氯胺对DBPs的重整进行了研究。结果表明，光降解遵循TOI>TOBr>TOCl的顺序，和处理过的地表水与低SUVA254背景不影响高度紫外线敏感的DBPs，如三碘甲烷（TIM）的光降解，二碘溴甲烷（DIBM），三溴甲烷（TBM）。氯化物的质量平衡结果，溴化物和碘化物表明，TOBr和TOI的主要光降解机理是卤化物释放支持的脱卤(即，Cl-,Br-和/或I-离子)。此外,光降解去除效果较高，当溴化DBPs形成高时。虽然低压紫外光有效去除卤化有机DBPs，随后使用消毒剂(Cl2和NH2Cl)改造的光降解DBPs，总DBPs浓度增加，这表明释放的Br-和I-离子将改革分配系统中的DBPs，存在或添加氧化剂(例如，增压氯化）在分配系统中。这项研究表明，尽管紫外光降解会减少分配系统中的卤化有机DBPs，尤其是更有毒的碘化和溴化DBPs，这将是一种更有效的技术，朝向分配系统或入口解决方案的终点，而不是在具有消毒后和停留时间的分配系统中。
