Rodriguez Manuel J, Serodes Jean, Roy Danielle
Ecole supérieure d'aménagement du territoire, Université Laval, 1624 Pavillon Savard, Quebec City, Que, Canada G1K-7P4.
Water Res. 2007 Oct;41(18):4222-32. doi: 10.1016/j.watres.2007.05.048. Epub 2007 Jun 3.
Most research on the occurrence of chlorinated disinfection by-products (DBPs) in drinking water has focused on trihalomethane (THM) formation and evolution, in particular within distribution systems. In this research, we investigated the variability of the occurrence of haloacetic acids (HAAs) during the treatment process in two facilities where surface water is pre-chlorinated before being treated by conventional physico-chemical processes. The investigation focused on both seasonal and point-to-point fluctuations of HAAs. In both facilities, samples were collected weekly during 1 complete year at four points in order to generate robust data on HAAs and on complementary parameters. The results showed that the initial formation of HAAs was the highest and the most variable in the plant where levels of DBP precursor indicators and the pre-chlorination dose were both higher and more variable. Subsequent formation of HAAs from the pre-chlorination point until the settled water occurred due to remaining levels of residual chlorine and DBP precursors. However, HAA levels and in particular dichloroacetic acid (DCAA) (the preponderant HAA species in the waters under study) decreased dramatically during filtration, very probably because of biodegradation within the filter. The effect of filtration on DCAA fate was season-dependant, with the highest degradation in warm water periods and practically no variation during winter. Statistical modeling was applied to empirically identify the operational factors responsible for HAA formation and fate. Model performance to identify HAA variability in waters following pre-chlorination was much better than for water following filtration, which is due to the lack of information on mechanisms and conditions favoring DCAA degradation.
大多数关于饮用水中氯化消毒副产物（DBPs）生成情况的研究都聚焦于三卤甲烷（THM）的形成与演变，尤其是在配水系统中的情况。在本研究中，我们调查了两座采用地表水的设施在处理过程中卤乙酸（HAAs）生成情况的变异性，这两座设施在采用常规物理化学工艺处理之前先进行预氯化。该调查聚焦于HAAs的季节性波动和逐点波动。在两座设施中，为了获取关于HAAs及补充参数的可靠数据，在一整年的时间里每周在四个点采集样本。结果表明，在DBP前驱物指标水平和预氯化剂量都更高且变化更大的工厂中，HAAs的初始生成量最高且变化最大。从预氯化点到沉淀水阶段，由于残留氯和DBP前驱物的剩余水平，会继续生成HAAs。然而，HAAs水平，尤其是二氯乙酸（DCAA）（在所研究水体中占主导的HAA种类）在过滤过程中显著下降，很可能是因为在滤池中发生了生物降解。过滤对DCAA归宿的影响取决于季节，在温暖水期降解程度最高，而在冬季几乎没有变化。应用统计模型来实证确定导致HAAs生成和归宿的运行因素。识别预氯化后水体中HAAs变异性的模型性能要比识别过滤后水体中HAAs变异性的模型性能好得多，这是由于缺乏关于有利于DCAA降解的机制和条件的信息。
