ÉSAD, Université Laval, Pavillon Félix-Antoine-Savard, 2325, rue des Bibliothèques, Québec G1V 0A6, Canada.
Ville de Québec, 214, avenue Saint-Sacrement, suite 210, Québec G1N 3X6, Canada.
Sci Total Environ. 2019 Nov 25;693:133517. doi: 10.1016/j.scitotenv.2019.07.323. Epub 2019 Jul 22.
As the third largest group of identified disinfection by-products (DBPs) by weight, halogenated acetaldehydes (HALs), were monitored for one year at numerous locations in two full-scale drinking water systems applying an ozone-chlorine sequential disinfection strategy. The HALs that were targeted included four trihalogenated acetaldehydes (THALs): chloral hydrate (CH), bromodichloroacetaldehyde (BDCAL), dibromochloroacetaldehyde (DBCAL) and tribromoacetaldehyde (TBAL). Three dihalogenated acetaldehydes (DHALs) were also included: dichloroacetaldehyde (DCAL), bromochloroacetaldehyde (BCAL) and dibromoacetaldehyde(DBAL). In addition to various sampling points in two distribution networks, this study also investigated the formation of HALs during water treatment and for the first time, reports the formation of DBAL before chlorine is applied. Low bromide levels in source waters from both systems resulted in the rare detection of DBAL and TBAL. CH accounted for >50% of total HALs (HAL7) with DHALs accounting for as little as 10% of HAL7, presumably due to the use of ozone-chlorine instead of ozone-chloramine. In the presence of chlorine residuals and with increasing water residence times, most HALs continued to form, more readily in warm water than in cold water. However, the spatial and temporal patterns for each HAL differed depending on speciation (THAL vs. DHAL) and water temperature. Compared to the relatively stable bromine incorporation factor (BIF) of THMs in the distribution systems, the decreasing BIFs of HALs according to water residence time increases suggested that bromine-containing THMs are more stable than their corresponding HALs. Re-chlorination at the extremities of the distribution networks demonstrated a significant impact on the occurrence and speciation of DBPs. In both full-scale systems, water temperature was shown to be the biggest contributing factor to HAL formation. The strong correlations between THM levels and THAL levels make it possible to predict the occurrence of THALs based on THMs.
作为第三大组被识别的消毒副产物（DBPs），卤代乙醛（HALs），在应用臭氧-氯序贯消毒策略的两个全规模饮用水系统的多个地点进行了为期一年的监测。所针对的 HALs 包括四种三卤代乙醛（THALs）：水合氯醛（CH）、溴二氯乙醛（BDCAL）、二溴氯乙醛（DBCAL）和三溴乙醛（TBAL）。还包括三种二卤代乙醛（DHALs）：二氯乙醛（DCAL）、溴氯乙醛（BCAL）和二溴乙醛（DBAL）。除了两个配水网络中的各种采样点外，本研究还调查了 HALs 在水处理过程中的形成情况，并且首次报告了在施加氯之前 DBAL 的形成情况。两个系统原水中的低溴水平导致 DBAL 和 TBAL 的罕见检测。CH 占总 HALs（HAL7）的>50%，DHALs 仅占 HAL7 的 10%，这可能是由于使用臭氧-氯而不是臭氧-氯胺。在有氯残留和增加水停留时间的情况下，大多数 HALs 继续形成，在热水中比在冷水中更容易形成。然而，每个 HAL 的时空模式取决于形态（THAL 与 DHAL）和水温。与分配系统中三卤甲烷（THMs）相对稳定的溴化系数（BIF）相比，根据水停留时间增加而降低的 HALs 的 BIF 表明，含溴的 THMs 比其相应的 HALs 更稳定。在配水网络的末梢进行再氯化，对 DBPs 的发生和形态产生了重大影响。在两个全规模系统中，水温被证明是 HAL 形成的最大贡献因素。THM 水平与 THAL 水平之间的强相关性使得根据 THMs 预测 THALs 的发生成为可能。
