Collaborative Research: Advanced Oxidation Processes for the Control of Iodinated Disinfection Byproducts in Drinking Water

在常规的水处理工艺中，氯等化学氧化剂被广泛用作消毒剂来灭活水中的病原体。然而，氯可与饮用水水源中的各种本底成分(如天然有机物、溴和碘)反应，形成不良和有毒的消毒副产物(DBPs)。目前，美国环保局对饮用水中11种DBPs的最高污染物水平(MCL)进行了监管，其中包括4种三卤代甲烷(THMs)、5种卤代乙酸(HAAs)、溴酸盐(Bro-3)和亚氯酸盐(ClO2-)。不受管制的碘化DBPs(i-DBPs)正受到越来越多的关注，因为它们比受管制的DBPs毒性大得多，并能损伤细胞和DNA。在饮用水水源消毒过程中，氯等化学氧化剂与碘和碘化化合物(例如，碘化X射线造影剂)反应时，会形成I-DBPs。因此，将碘和碘化合物氧化转化为碘酸盐(IO3-)，这是一种无毒的碘营养微量元素来源，已成为控制和减缓水处理系统中I-DBPs形成的一种很有前途的单元工艺。然而，当前水处理工艺有效地将碘和ICs转化为碘酸盐的能力面临着几个挑战，包括溴化物同时氧化成溴酸盐和有毒的溴化DBPs，以及碘/ICs不完全转化为碘酸盐，这也可能导致最终产品水中形成I-DBPs和其他受监管的DBPs。该合作项目的目标是探索高级氧化工艺(AOPS)和综合处理系统的开发，这些工艺可以有效地将碘和IC氧化并转化为碘酸盐，同时最大限度地减少和防止产品饮用水中有毒的I-DBPs和受监管的DBPs的形成。该项目的成功完成将使社会受益，因为它将发展新的基础知识，指导设计和部署更有效的水处理工艺和系统，以减轻和消除水消毒过程中的i-DBPs的形成。还将通过学生教育和培训为社会带来更多好处，包括指导南达科他州矿业和技术学院的一名研究生和一名本科生以及南达科他州州立大学的一名研究生。饮用水处理过程中产生的碘化消毒副产物(I-DBPs)在低浓度下具有高度毒性，并被发现具有细胞毒性和遗传毒性。在饮用水处理过程中，碘(I-)和碘化X射线造影剂(ICM)是两种最常见的碘源，它们可以与消毒剂(如氯和氯胺)反应生成I-DBPs。在水处理系统中，将碘和碘化合物(如ICM)氧化和转化为碘(IO3-)，这是一种无毒的碘营养微量元素来源，已成为控制和减少I-DBPs形成的有希望的单元工艺。该项目的总体目标是通过仔细选择和优化高级氧化工艺(AOPS)并将AOPS与常规工艺相结合，促进控制饮用水处理中新出现的间歇二溴联苯和受管制的二溴联苯并苯二酚所需的基础科学和工程知识。拟议研究的核心指导假设是，要成功控制饮用水处理系统中新出现的I-DBPs和受管制的DBPs，需要有效地氧化碘物种和碘化合物并将其转化为碘酸盐，仔细管理溴的形成，以及在消毒前部分(体面)去除DBP前体NOM(天然有机物)。该研究的具体目标是1)研究AOPS的利用，包括高铁酸盐(Fe[VI])、臭氧(O3)、紫外光分解和紫外光分解臭氧，以优化碘和ICM氧化成碘酸盐；2)研究AOPS与常规工艺的集成，包括氯化和活性碳吸附，以最大限度地减少I-DBPs和受监管的DBPs的形成；以及3)建立测量碘物种和I-DBPs的分析方法，以揭示和量化碘和ICM向I-DBPs和总有机碘的转化途径。该项目的成功完成有可能促进AOPS对无机和有机碘物种/化合物的反应性和转化的基本了解，以指导针对碘源的处理工艺的设计和开发，以有效缓解水处理系统中的I-DBPs和受监管的DBPs。为落实该项目的教育和培训目标，首席调查员(PI)建议利用南达科他州矿业与技术学院(SDSMT)和南达科他州州立大学的现有计划，招募和指导女学生参与该项目。此外，PIS计划与饮用水处理专业人员互动和合作，以应对南达科他州的水质挑战，参与当地社区外展活动，并与SDSMT艾芬豪国际中心合作，吸引和指导来自非洲大陆的国际学生。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Chemical oxidants such as chlorine are widely utilized as disinfectants to inactivate waterborne pathogens in conventional water treatment processes. However, chlorine can react with various background constituents in drinking water sources (e.g., natural organic matter, bromide, and iodide) to form undesirable and toxic disinfection byproducts (DBPs). Currently, the US EPA regulates the maximum contaminant levels (MCLs) of 11 DBPs in drinking water including 4 trihalomethanes (THMs), 5 haloacetic acids (HAAs), bromate (BrO-3), and chlorite (ClO2-). Unregulated iodinated DBPs (I-DBPs) are receiving increased attention as they are significantly more toxic than the regulated DBPs and can damage cells and DNA. I-DBPs are formed when chemical oxidants such as chlorine react with iodine and iodinated compounds (e.g., iodinated X-ray contrast media) during the disinfection of drinking water sources. Thus, the oxidation and conversion of iodine and iodinated compounds (ICs) to iodate (IO3–), a nontoxic source of iodine nutritional trace element, has emerged as a promising unit process to control and mitigate the formation of I-DBPs in water treatment systems. However, the ability of current water treatment processes to efficiently convert iodine and ICs to iodate suffer from several challenges including the concurrent oxidation of bromide to bromate and toxic brominated DBPs, and the incomplete transformation of iodine/ICs to iodate which can also lead to the formation of I-DBPs and other regulated DBPs in the final product water. The goal of this collaborative project is to explore the development of advanced oxidation processes (AOPs) and integrated treatment trains that can efficiently oxidize and convert iodine and ICs to iodate while minimizing and preventing the formation of toxic I-DBPs and regulated DBPs in the product drinking water. The successful completion of this project will benefit society through the development of new fundamental knowledge that could guide the design and deployment of more effective water treatment processes and systems for mitigating and eliminating and the formation of I-DBPs during water disinfection. Additional benefits to society will be achieved through student education and training including the mentoring of one graduate student and one undergraduate at the South Dakota School of Mines and Technology and one graduate student at South Dakota State University. Iodinated disinfection byproducts (I-DBPs) formed in drinking water treatment are highly toxic at low concentrations and have been found to be cytotoxic and genotoxic. Iodide (I–) and iodinated X-ray contrast media (ICM) are the two most common iodine sources that can react with disinfectants (e.g., chlorine and chloramines) to produce I-DBPs during drinking water treatment. The oxidation and conversion of iodine and iodinated compounds such as ICM to iodate (IO3–), a nontoxic source of iodine nutritional trace element, has emerged as promising unit process to control and mitigate the formation of I-DBPs in water treatment systems. The overarching goal of this project is to advance the fundamental science and engineering knowledge required to control emerging I-DBPs and regulated DBPs in drinking water treatment through careful selection and optimization of advanced oxidation processes (AOPs) and integration of the AOPs with conventional processes. The core guiding hypothesis of the proposed research is that the successful control of emerging I-DBPs and regulated DBPs in drinking water treatment systems would require the efficient oxidation and conversion of iodine species and iodinated compounds to iodate, the careful management of bromide formation, and the partial (decent) removal of NOM (Natural Organic Matter), a DBP precursor, prior to disinfection. The specific objectives of the research are to 1) to investigate the utilization of AOPs, including ferrate (Fe[VI]), ozone (O3), UV photolysis, and UV photolysis with O3, to optimize the oxidation of iodine and ICM to iodate; 2) investigate the integration of AOPs with conventional processes, including chlorination, and activated carbon sorption, to minimize the formation of both I-DBPs and regulated DBPs; and 3) develop analytical methods for measurement of iodine species and I-DBPs to unravel and quantify the transformation pathways of iodine and ICM to I-DBPs and total organic iodine. The successful completion of this project has the potential to advance the fundamental understanding of the reactivity and transformations of inorganic and organic iodine species/compounds by AOPs to guide the design and development of iodine source-specific treatment processes for effective mitigation of both I-DBPs and regulated DBPs in water treatment systems. To implement the education and training goals of this project, the Principal Investigators (PIs) propose to leverage existing programs at the South Dakota School of Mines and Technology (SDSMT) and South Dakota State University to recruit and mentor female students to work on the project. In addition, the PIs plan to interact and collaborate with drinking water treatment professionals to address water quality challenges in South Dakota, engage in local community outreach events, and collaborate with the SDSMT Ivanhoe International Center to engage and mentor international students from the African continent.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.