Collaborative Research: WRF: GOALI: Securing the Future of Direct and Indirect Potable Reuse: N-nitrosodimethylamine (NDMA) Formation Pathways and Precursors

在水处理过程中使用消毒剂有效地根除了水传播疾病，但这些消毒剂会形成低浓度的致癌化学副产品。这些副产物往往在消毒废水中以较高的水平形成，这一并发症通常会随着河流、湖泊和含水层的时间推移而减轻，因为这些致癌化学物质可以降解。然而，在饮用水回用情况下，这种降解时间减少了，使饮用水回用技术的未来面临风险。该项目将研究致癌化学物质n -亚硝基二甲胺（NDMA）在饮用水回用废水深度处理过程中形成的机制和潜在解决方案。该项目还将增加大学生和中学生的教育机会，并在两个工业伙伴和一所大学的合作下提供新的教育和研究基础设施。如果成功，这项研究可以进一步实现饮用水的再利用，这是一项有价值的技术，可以支持我们国家的水安全。n -亚硝基二甲胺（NDMA）是氯胺消毒过程中形成的致癌化合物。进入饮用水处理厂的NDMA前体被认为起源于废水。基于正在进行的NDMA前体研究，饮用水再利用系统中使用的一些技术已被确定为减少NDMA发生和形成的技术：反渗透（RO），物理去除前体，强紫外线（UV）光分解NDMA为亚硝酸盐和二甲胺。虽然这些系统有效地减少了90%的NDMA的形成，但在消毒水中，NDMA的形成仍然会在生理相关浓度（5 ng/L）下发生。这些前体的来源尚不清楚，但初步研究表明，处理过程本身可能会将NDMA前体的新子集释放到水中。本研究的总体假设是：饮用水回用的高级处理通过从RO中浸出NDMA前体和/或在UV，过氧化氢（UV/过氧化氢）处理过程中将非活性有机物转化为NDMA前体，从而为成品水贡献NDMA前体。这项研究的基本原理是NDMA具有高度致癌性，虽然RO和UV/过氧化物可以去除大多数NDMA前体，但它们也会改变水的化学性质，从而可能导致新的NDMA前体的产生。该假设将通过追求4个具体目标来验证：1)确定形成NDMA的已知前体和化学添加剂的反应性；2)确定紫外/过氧化转化产物和动力学，将非活性有机N“上转化”为活性NDMA前体；3)表征NDMA前驱体池在深度水处理过程中整体化学特性的变化；4)确定在中试规模上最小化NDMA形成的操作变化。这些目标将使用由研究小组成员开创的新型质谱和分离技术进行研究。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The use of disinfectants during water treatment has effectively eradicated waterborne illness, but these disinfectants form low concentrations of carcinogenic chemical by-products. These by-products tend to form at higher levels in disinfected wastewater, a complication that is usually alleviated by time in rivers, lakes, and aquifers that allows for the degradation of these carcinogenic chemicals. However, this time for degradation is reduced in potable water reuse scenarios, putting the future of potable water reuse technologies at risk. This project will investigate the mechanisms of and potential solutions to the formation of a carcinogenic chemical, N-nitrosodimethylamine (NDMA), during advanced treatment of wastewater targeted for potable reuse. The project will also enhance educational opportunities for students at the college and middle school level, and provide new educational and research infrastructure in a partnership between two industrial partners and a university. If successful, this research can further enable the use of potable water reuse, a valuable technology that could support our nation's water security. N-nitrosodimethylamine (NDMA) is a carcinogenic compound that forms during chloramine disinfection. NDMA precursors that enter drinking water treatment plants are thought to originate in wastewater. Based on ongoing NDMA precursor research, some technologies used in potable reuse systems have been identified as technologies that reduce NDMA occurrence and formation: reverse osmosis (RO), which physically removes precursors, and strong ultraviolet (UV) light, which photolyzes NDMA to nitrite and dimethylamine. While these systems effectively reduce NDMA formation by 90%, NDMA formation still occurs at physiologically relevant concentrations (5 ng/L) in the disinfected water. The sources of these precursors are unknown, but preliminary research indicated that the treatment processes themselves may release a new subset of NDMA precursors into the water. The overarching hypothesis of this research is: Advanced treatment for potable reuse contributes NDMA precursors to the finished water via leaching NDMA precursors from RO and/or transforming unreactive organic matter to NDMA precursors during UV, hydrogen peroxide (UV/peroxide) treatment. The rationale that underlies the research is that NDMA is highly carcinogenic, and while RO and UV/peroxide remove most NDMA precursors, they also change the water chemistry which may cause occurrence of new NDMA precursors. The hypothesis will be tested by pursuing 4 specific aims: 1) Determine the reactivity of known precursors and chemical additions in forming NDMA; 2) Identify UV/peroxide transformation products and kinetics that "up-convert" unreactive organic N to reactive, NDMA precursors; 3) Characterize changes in bulk chemical characteristics of the NDMA precursor pool during advanced water treatment; and 4) Identify operational changes that minimize NDMA formation at pilot-scale. These aims will be investigated using novel mass spectrometric and separations techniques pioneered by members of the research team.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.