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源性疾病，但这些消毒剂形成的致癌化学副产物浓度较低。这些副产品往往在消毒废水中形成较高水平的副产品，这种并发症通常会随着时间的推移而在河流、湖泊和含水层中得到缓解，从而允许这些致癌化学物质的降解。然而，在饮用水再利用的情况下，这一降解时间减少了，将饮用水再利用技术的未来置于危险之中。该项目将调查在针对饮用水重复使用的废水的深度处理过程中形成致癌化学物质N-亚硝基二甲胺(NDMA)的机理和可能的解决方案。该项目还将增加大学生和中学生的教育机会，并在两个行业合作伙伴和一所大学之间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，这是一项可以支持我国水安全的有价值的技术。N-亚硝基二甲胺(NDMA)是氯胺消毒过程中形成的一种致癌化合物。进入饮用水处理厂的NDMA前体被认为来自废水。根据正在进行的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)，它物理地去除前体，以及强紫外线(UV)，它将NDMA光解为亚硝酸盐和二甲胺。虽然这些系统有效地将NDMA的形成减少了90%，但在消毒后的水中，NDMA的形成仍然在生理相关的浓度(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新的NDMA前体释放到水中。本研究的主要假设是：饮用水回用的深度处理通过从反渗透中淋洗NDMA前体和/或在UV、过氧化氢(UV/POPO)处理期间将非活性有机物转化为NDMA前体，从而将NDMA前体贡献到成品水中。这项研究的基本原理是，NDMA是高度致癌的，虽然RO和UV/POVER去除了大部分NDMA前体，但它们也改变了水化学，这可能会导致新的NDMA前体的出现。这一假设将通过追求4个具体目标来验证：1)确定已知前体和化学添加剂在形成NDMA过程中的反应性；2)确定UV/过氧化氢转化产物和动力学，将非反应性有机N“上转化”为活性的NDMA前体；3)表征深度水处理期间NDMA前体池的整体化学特征的变化；以及4)确定在中试规模上最大限度地减少NDMA形成的操作变化。这些目标将使用研究团队成员首创的新型质谱学和分离技术进行研究。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。

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.