不同消毒方式供水管网中消毒副产物的分布特征

Distribution Characteristics of Disinfection Byproducts in Drinking Water Distribution Systems of Different Disinfection Methods

摘要:

针对我国东南沿海地区4个使用不同类型二次消毒剂（氯、氯胺、二氧化氯）的局部管网水样的中三卤甲烷（THMs）、卤乙酸（HAAs）、卤乙腈（HANs）的分布特征及影响因素进行了分析。结果表明，3座城市DBPs的超标风险整体较低，采集的117份水样中有10份水样THMs超过国标限值，其余DBPs均符合标准。以氯为消毒剂的管网水样中THMs浓度和HANs浓度远高于其他管网，以二氧化氯为消毒剂可以减少消毒副产物THMs的生成，但以氯胺为消毒剂的上海地区HAAs浓度较高，是其他3个系统的5~19倍，可能与原水中HAAs前体物含量较高有关。在SH-NH?Cl系统中，消毒剂浓度与输配距离成反比（r = -0.57），同时该系统中硝酸盐、亚硝酸盐及氨氮浓度也随距离变化，说明饮用水在管网输送过程中余氯被逐渐消耗，同时管网中发生了硝化反应，氨氮被氧化为亚硝酸盐和硝酸盐。WJ-Cl₂系统中DBPs与输配距离相关，HANs浓度沿程减少（r = -0.49），HAAs浓度沿程增加（r = 0.45）。此外，建筑管网中长停滞时间也会影响水样理化指标。该研究揭示了不同类型二次消毒剂的管网水中DBPs浓度水平和变化规律，研究结果可为不同地区水质安全评价和风险控制提供依据。

Abstract:

This study analyzes the distribution characteristics and influencing factors of three types of disinfection by-products（DBPs）—trihalomethanes （THMs）， haloacetic acids （HAAs）， and halonitriles （HANs）—in water samples from drinking water distribution systems in the southeastern coastal region of China. These distribution systems utilize three different secondary disinfectants： chlorine， chloramine and chlorine dioxide. The results indicate a relatively low risk for exceeding DBPs limits in the three cities studied. Among the collected 117 water samples， 10 exceeded the standard limit for THMs， while other DBPs were within compliance. Water distribution systems using chlorine as a disinfectant showed significantly higher concentrations of THMs and HANs in comparison with other water distribution systems. Chlorine dioxide effectively reduced the formation of THMs in comparison with the chlorine. Chloramines were used in Shanghai， however， the concentration of HAAs was 5 to 19 times higher than that in the other three systems， potentially due to higher levels of HAA precursors in the source water. Concentration of disinfectants and DBPs in drinking water varied with distances. In the SH-NH₂Cl system， disinfectant concentration showed an negative correlation with distance （r = -0.57）. This system also changed in nitrate， nitrite， and ammonia nitrogen concentrations along the distance， suggesting gradual chlorine decrease and nitrification in the distribution systems， leading to the oxidation of ammonia to nitrite and nitrate. In the WJ-Cl₂ system， a significant correlation was found between DBPs and distance. The concentration of HANs decreased with distance （r =-0.49）， while HAAs concentration displayed an increase along the path （r = 0.45）. Moreover， long stagnation time within premise plumbings can also impact water physicochemical qualities. This study reveals the concentration and variation of DBPs in distribution systems water using different types of secondary disinfectants. The findings provide a basis for water quality assessment and risk control in various regions.