饮用水氯化消毒有机(伪)氯胺的产生机制与控制方法研究

Organic chloramines, formed during dissolved nitrogen chlorination and chloraminaiton, contribute the major components in the total chlorine residue. Due to poor oxidizing capacity and very weak sterilization ability, organic chloramines are also known as pseudo chloramines. Since organic chloramines cannot be determined separately during the regular total chlorine residue analysis so far. The combined residual chlorine obtained is actually the sum of organic and inorganic chloramines indeed, which results in the overestimated the effective chlorine residue in finished and pipe net waters and thus increasing pathogenic risks of microorganism. Moreover, organic chloramines are also the intermediates for extreme toxic nitrogenous disinfection by-products (N-DBPs) during chlor(am)ination. Organic chloramines became newly defined emerging containments and received great attentions in drinking water, recently. In order to minimize risk of organic chloramines in drinking water, this project focus on the formation mechanism of organic chloramines and control methods in drinking water treatment and the following main contents will be investigated: (1) to invent the effective method by selective quenching method for organic chloramines determination in disinfected waters; (2) to clarify formation mechanism and discover the constitute of organic chloramines precursors in micro-polluted raw water. The relation between water types, fractional of dissolved organics and I-DBPs formation potential will be fully investigated; (3) to illustrate the stability of organic chloramines and thus find the transform mechanism to N-DBPs. (4) to investigate the fate of organic chloramines and precursors in drinking water treatment. A calculated model for chlorine needed during disinfection is expected to be build. Moreover, the effective methods to minimize formation risk of organic chloramines would be provided. As shown above, the basic theory of organic chloramines control in drinking water treatment will be presented in this project.

水中溶解性有机氮（DON）与氯（胺）反应产生的有机氯胺是总余氯的重要组成部分，其氧化性很弱、杀菌能力非常有限，因此也被称为伪氯胺。鉴于总余氯测定中有机和无机氯胺尚无法有效区分，这将导致出厂水和管网水中有效余氯值的高估，使得水质生物风险大大增加。同时，其也是高致毒性N-DBPs生成的前体物。有机氯胺已成为本领域开始关注的重要水质问题。本项目将在前期研究基础上，重点开展有机氯胺的生成控制理论研究。通过原创的选择性淬灭方法研究，获得有效的有机氯胺检测新方法；解析微污染原水DOM类型及组成与有机氯胺生成潜能间联系，揭示其产生及其前体物分子组成规律；探索有机氯胺的稳定性与转化形成N-DBPs的规律，掌握其转变重要途径；通过净水工艺归趋特性研究，建立基于有机氯胺补偿的消毒需氯新模型，揭示净水单元对其生成潜能的作用规律，探究有效的风险削减方法；最终为我国饮用水处理过程中有机氯胺的风险控制提供理论依据。

饮用水消毒后产生的有机氯胺是总余氯的重要组成部分，其氧化性很弱、杀菌能力非常有限，也被称为伪氯胺。有机氯胺存在可导致出厂（管网）水中有效余氯值的高估，使得水质生物风险大大增加，也是高致毒性N-DBPs生成的重要前体物。本课题以饮用水消毒过程中有机氯胺的产生机制与控制理论为研究重点，系统性开展了有机氯胺定量新方法、前体物组成辨析、产生与转化规律、归趋行为与削减理论等研究工作。课题原创性提出并建立了基于NaAsO2选择淬灭性的水中无效氯胺检测新方法，形成规范性测试步骤和计算方法，实现了快速定量识别有机氯胺中氧化杀菌能力最弱的无效组分，直接解决了伪氯胺难直接定量的难题；通过解析微污染原水不同分子区间溶解性有机物、对比不同天然有机物的有机氯胺生成特性，阐明清楚了小分子和亲水性有机物易与氯（胺）反应产生有机氯胺，同时发现藻源有机物为有机氯胺的重要前体物，其产率远高于腐殖质和富里酸等有机物；藻源有机物反应产生的有机氯胺更不稳定，在后续氯（胺）消毒过程中，可进一步与消毒剂反应转化生成多种高致毒性C-DBPs和N-DBPs，其中自由氯消毒明显高于一氯胺消毒方式；通过对典型有机氯胺前体化合物--肌酸酐的氯化降解动力学研究，获得了典型有机氯胺及其前体物的反应动力学特征与基元反应速率常数、中间产物和降解机制，并明确了其在后续氯化消毒中转化产生N-DBPs的详细反应路径，掌握了有机氯胺生成和进一步降解转化的新途径与重要影响因素；系统研究了有机氯胺及其前体物在饮用水处理工艺和输配全流程中的变化规律，建立了有机氯胺生成模型，探明了UV消毒对有机物氯胺生成和转化影响作用规律，获得了预氧化、常规与深度处理以及管网输水过程中有机氯生成与转变特征。本课题相关研究成果可为我国饮用水处理过程中有机氯胺与N-DBPs的有效控制提供理论依据和技术支持。