饮用水净化工艺全流程中的卤乙腈分布特征及其前体物研究

Haloacetonitriles, as a new type of nitrogenous disinfection by-products, has attracted more and more attention because of its higher genetic toxicity than chloroform. There is no country or international organization but WHO putting Haloacetonitriles in the relevant regulations for drinking water.Source water quality is poor in almost part of China, and chlorine or chloramine disinfection is commonly used, which leads to greater damage by haloacetonitriles.Besides, the monitoring data ofhaloacetonitriles is rarely.Thus the effective control of its content is very important for the safety of water. This research aims at the water from the whole process of drinking water production in J city, named fromsource water of a certain tap water plant, water intake, water purification process and effluent water. The haloacetonitriles potentials were measured drinking water fractions from the whole production process isolated by resins, with the purpose of clearly understanding the effect of purification process on haloacetonitriles potentials. Besides, the methods of comprehensive characterization, UV, fluorescence, and Fourier transform infrared spectrum are chosen to investigate the relationship between organic matter and haloacetonitriles potentials, which would be helpful to analyze the functional and molecular structure for haloacetonitriles precursors. Based on the above results, model organic matter during chlorinationdisinfection is investigated to further clarify the behavior and mechanism of haloacetonitriles formation. This research will be of great significance to establish new technology of water quality security with synergistic effects of standards and effects.

卤乙腈作为一类新型含氮消毒副产物，因为具有比三卤甲烷类消毒副产物更高的遗传毒性而引起研究者的广泛关注。除了世界卫生组织，其他国家及国际组织还未将其列入相关规范。我国大部分城市水源水质较差，普遍采用氯或氯胺消毒，卤乙腈产生的危害会更大，然而对卤乙腈的监测数据很少，因此有效控制其含量对饮用水安全具有重要意义。本研究拟针对J市某自来水厂的水源水、取水口、净化水工艺等全流程的水样进行树脂分离成亲水、疏水、酸碱中性等6类有机物，通过考察每类有机物的卤乙腈生成势，明确氯消毒过程中卤乙腈生成情况及自来水净化技术对卤乙腈的影响。与此同时，采用综合特性表征和紫外、荧光和傅里叶红外联合的光谱学表征手段，分析有机物表征参数与卤乙腈生成势的相关性，解析卤乙腈前体物的特征官能团或分子结构，并选择模式前体物进行验证，以进一步明晰卤乙腈的生成行为和机理，对于建立标准与效应协同调控的水质安全保障新工艺具有重要意义。

本文以北方多个地表水源及其实际的处理工艺为研究背景，对处理工艺的延流程的水质基本处理情况、天然有机物变化情况和卤乙腈及其消毒副产物前体物的分布状况进行研究，得出卤乙腈的分布特征及形成规律。.在常规净水工艺流程中可发现，四种卤乙腈仅有三种在出厂水中可被检出，总浓度范围在4.22~6.97 μg/L之间。从树脂分级的角度观察研究得出在全流程中疏水酸组分为全流程中DOM的主要成分，也为卤乙腈的前体物主要组成成分占比为32.07%~43.78%，亲水碱组分与疏水碱组分含量在全流程中占比最低。混凝沉淀处理单元对疏水酸组分、亲水中组分的含量去除效果最好去除率为56%、39%。从前体物的角度观察，净水工艺中的各环节对各种形式的有机物都有去除效果。其中混凝效果对DOC和UV254的去除率分别可达33.35%和28.55%；过滤对DOC和UV254的平均去除率分别为5.44%和0.46%；消毒对DOC平均去除率为8.8%，对UV254的去除率效果较好，平均去除率可达到17.04%。经过全流程工艺之后，CODMn的去除率可达到13.42~35.22%之间。荧光物质中，经历各流程的去除后各种成分所占比例变化较小，但是各工艺环节对各类有机物都有去除效果，其中深度处理工艺和消毒工艺对荧光物质的去除效果优于其他工艺。傅里叶红外光谱可以看出混凝沉淀工艺对于酯醇醚类和腐殖酸、富里酸类物质的去除效果更好，而过滤工艺对于脂肪族化合物的去除效果更佳，而臭氧活性炭工艺会将小分子的羧酸和醛类有机物物质彻底去除，将其氧化成CO2和H2O。预加氯对去除原水中DOM有明显效果。采用预氯化工艺中， TCAN生成势变化不稳定， DBAN生成势在全流程中呈现明显下降趋势。DCAN生成势受预氧化影响较小，DCAN生成势在各个环节占比最高为48%~72%。.本研究明对进一步明晰卤乙腈的生成行为和机理，对于建立标准与效应协同调控的水质安全保障新工艺具有重要意义。