饮用水中碘代消毒副产物的生成机制与控制方法研究

Iodinated disinfection by-products (I-DBPs) are newly defined emerging containments in drinking water and shows strong carcinogenic, teratogenic and mutagenic potential. With the present of iodide in the raw water, I-DBPs tend to be formed in the finished water after disinfection especially alterative chloramination, which is widely used drinking water plant for the raw water with high organic contents in China. In order to minimize risk of I-DBPs in drinking water, this project focus on the formation mechanism of I-DBPs and control methods in drinking water treatment and the following main contents will be investigated: (1) to indentify the new formation mechanism of I-DBPs during pre-oxidation in drinking water treatment as well as the effect of impacts; (2) to discover the constitute of I-DBPs precursors in micro-polluted raw water. The relation between fractional of dissolved organics and I-DBPs formation potential will be investigated; (3) to find typical organic iodine precursors in raw water and examine the new formation pathway of I-DBPs in absence of iodide. Kinetics and degradation pathways of these precursors during chlor(am)ination will be investigated as well; (4) to investigate the transformation of I-DBPs and precursors in pre-oxidation, conventional and advanced drinking water treatment. A predict models for I-DBPs formation is expected to be build. Moreover, the effective methods to minimize I-DBPs pollution would be provide. As shown above, the reliable and integrated theory of I-DBPs control in drinking water will be presented in this project.

I-DBPs是目前国际饮用水领域开始关注的新型强"三致"消毒副产物。我国微污染原水有机物含量高，水厂普遍采用氯胺消毒方式，在水中存在碘离子条件下，可导致出厂水中较高浓度I-DBPs的产生。本项目以饮用水净水工艺中I-DBPs的产生机制和控制理论为研究重点，开展预氧化中I-DBPs生成规律研究，阐明饮用水中I-DBPs产生新机制；解析微污染原水DOM组成与I-DBPs生成潜能间联系，揭示I-DBPs前体物的分子组成规律；探索原水中存在的典型有机碘前体物，探明其氯（胺）化反应特征和I-DBPs生成规律，掌握无碘离子条件下I-DBPs形成新途径；通过饮用水净水工艺归趋特性研究，建立水中I-DBPs生成预测经验模型，明晰预处理、常规和深度处理工艺单元中I-DBPs及其生成潜能的变化规律，探究有效的削减方法；最终为我国饮用水处理过程中I-DBPs的有效控制提供理论依据。

I-DBPs是目前国际饮用水领域开始关注的新型强“三致”消毒副产物。当水源水中存在碘离子和有机碘化合物条件下，水厂采用自由氯、氯胺消毒时，出厂水存在较高的I-DBPs生成风险。本项目以饮用水净水工艺中I-DBPs的产生机制和控制理论为研究重点，系统性开展了饮用水中I-DBPs的产生新机制、I-DBPs前体物的识别与辨析、I-DBPs及其前体物在净水工艺中的归趋行为与I-DBPs控制等研究工作。课题在国际上率先报导了饮用水高锰酸钾、二氧化氯预氧化过程中可直接产生I-DBPs的现象，阐明了反应过程中碘形态转变规律和I-DBPs生成新机制，明晰了关键的影响因素和有效的控制途径；通过微污染原水中有机物的分子组成区间切割与多类型DBPs生成潜能关联试验，发现在各分子区间均呈现I-DBPs氯胺化生成潜能原高于氯化生成潜能，I-DBPs的前体物与C-DBPs前体物分子组成规律基本相似，以小分子和疏水性有机物为主；研究发现水中广泛存在的有机碘化合物也可以与氯（胺）发生反应生成I-DBPs，尤其在紫外与氯（胺）联合消毒的条件下，有机碘化合物和碘酸盐均可快速降解并使得I-DBPs产率大幅提升，是导致无碘离子条件下I-DBPs形成的主要原因；通过有机碘的氯（胺）化、紫外降解有机碘和碘酸盐、紫外/氯（胺）联合降解等试验，获得了碘帕醇等有机碘化合物、碘酸盐的反应动力学特征与基元反应速率常数、中间产物、降解机制和I-DBPs变化的规律，掌握了导致I-DBPs生成的新途径与重要影响因素；通过净水工艺中I-DBPs产生特性与生成潜能归趋特性研究，构建了SPME-GC-MS检测水中痕量I-THMs和I-DBPs生成潜能定量的方法体系，建立了出厂水中I-THMs的生成经验模型，探明了饮用水常规和深度处理单元中I-DBPs生成潜能的变化规律，提出工艺中有效控制I-DBPs的技术方法。研究成果可以为我国饮用水处理过程中I-DBPs的有效控制提供可靠的技术理论支持。