Formation of Halonitromethanes and Nitrosamines During Ozonation in Drinking Water Treatment

项目负责人：Tanju karanfil提案编号：cbet -1066567机构：Clemson university标题：饮用水处理臭氧化过程中硝基甲烷和亚硝胺的形成硝基甲烷（HNMs）和亚硝胺构成了水处理过程中可以形成的两类重要的消毒副产物（DBPs）。HNMs的细胞毒性和遗传毒性比任何受调节的有机dbp高几个数量级，而亚硝胺的致癌风险水平非常低（即ng/L）。π吗?最近的研究表明，与饮用水处理中使用的其他典型消毒方案相比，臭氧氯化过程中HNM的形成明显更高。研究还表明，随着水中溶解有机氮（DON）含量的增加，HNM的形成也随之增加。然而，人们对DON成分的作用和导致HNM形成的前体的身份知之甚少。此外，在臭氧化过程中亚硝胺的形成是有争议的。虽然以前的研究表明，臭氧化减少了n -亚硝基二甲胺（NDMA）的形成，但最近的研究报道，在实验室研究和全规模臭氧化工厂中，臭氧化后NDMA的形成都相当可观。因此，研究臭氧化过程中hnm和亚硝胺的形成，了解其形成和物种形成的控制因素具有重要意义。该项目旨在系统地研究臭氧化过程中hnm和亚硝胺的形成，并深入了解它们的潜在前体和形成机制。我们假设N-DBPs的形成是前体特异性的，不同的前体/机制会参与HNM或亚硝胺的形成。因此，在本研究中，我们假设了各种形成机制，并提出了实验计划来研究这些机制。PI和同事们将首先用一组精心挑选的含氮有机化合物模型进行实验（任务1）。将分析反应中间体，以检查提出的形成机制，并深入了解hnm和亚硝胺的形成（任务2）。还计划在选定的自然水域进行监测研究（任务3），以检查前体（基于任务2和3）与dbp （HNM或亚硝胺）之间的关系。提出的工作是新颖的，因为它将是第一次提出的机制将被调查。这些发现有望为研究天然水体中不同有机氮组分在臭氧化过程中形成hnm和亚硝胺中的潜在作用提供重要信息。了解hnm和亚硝胺的形成对于找到控制这些化合物的策略至关重要。在美国大约有250个臭氧化工厂，其中一些非常大（500-800 MGD），服务于非常大的人口。研究结果将为世界各地的臭氧化工厂提供重要信息（例如，臭氧化在欧洲广泛实施）。美国相当多的公用事业公司一直在探索其他方法，以遵守第二阶段D/DBP规则的严格要求。臭氧化是一种可用的替代方法。因此，研究结果将是重要的公用事业考虑臭氧化。从这项工作中获得的知识将提高我们对HNM和亚硝胺形成性质的理解，并直接影响从业者。在处理设施中控制这些化合物形成的能力。美国环保署和各州监管机构可以从开发当前和未来管理这些化合物的程序的结果中受益。实施这一项目还将促进不同背景和水平的广泛学生的培训和教育。PI将通过这个项目提供创造性探究研究课程，这是克莱姆森大学的一个独特项目，让来自不同院系的不同学科的本科生在小型团队项目中工作，并获得大学学分。参与的学生将学习水处理过程、应用化学（即DPB的形成）以及如何进行科学研究。该项目还将为高中生和本科生提供机会，特别是来自代表性不足群体的学生。

PI: Tanju KaranfilProposal Number: CBET-1066567Institution: Clemson UniversityTitle: Formation of Halonitromethanes and Nitrosamines During Ozonation in Drinking Water TreatmentHalonitromethanes (HNMs) and nitrosamines constitute two important classes of disinfection byproducts (DBPs) that can form during water treatment. HNMs have orders of magnitude higher cytotoxicity and genotoxicity than any of the regulated organic DBPs, while nitrosamines pose cancer risk at very low levels (i.e., ng/L). The PI?s recent research has shown that HNM formation was significantly higher during ozonation-chlorination as compared with other typical disinfection scenarios used in drinking water treatment. It was also demonstrated that the HNM formation increased with an increase in dissolved organic nitrogen (DON) content in water. However, little is known about the role of DON components and the identity of precursors causing HNM formation. Furthermore, the formation of nitrosamines during ozonation is controversial. Though previous studies have shown that ozonation decreased N-nitrosodimethylamine (NDMA) formation, recent works have reported an appreciable amount of NDMA formation after ozonation in both lab studies and full scale ozonation plants. Therefore, it will be critically important to investigate the formation of HNMs and nitrosamines during ozonation, and to understand the factors controlling their formation and speciation.The PI seeks to systematically investigate formation of HNMs and nitrosamines during ozonation, and to gain insight to their potential precursors and formation mechanisms. We hypothesize that the formation of N-DBPs is precursor specific, and different precursors/ mechanisms will involve in the formation of HNM or nitrosamines. Therefore, in this study, various formation mechanisms have been postulated and experimental plans are proposed to investigate the proposed mechanisms. The PI and coworkers will initially perform experiments with a set of carefully selected model nitrogenous organic compounds (Task 1). Reaction intermediates will be analyzed to examine the proposed formation mechanisms and to gain insight to the formation of HNMs and nitrosamines (Task 2). A monitoring study (Task 3) in selected natural waters is also planned to examine the relationship(s) between the precursors(based on Task 2 and 3) and the DBPs (HNM or Nitrosamines). The proposed work is novel because it will be the first time that the proposed mechanisms will be investigated. The findings are expected to provide important information about the potential role(s) of different organic nitrogen components in natural waters in the formation of HNMs and nitrosamines during ozonation.Understanding the formation of HNMs and nitrosamines is vital for finding strategies to control these compounds. There are approximately 250 ozonation plants in the US, and some of them are quiet large (500-800 MGD), serving very large populations. Research results will provide important information for ozonation plants worldwide (e.g., ozonation is widely implemented in Europe). An appreciable number of utilities in the US have been exploring alternative approaches to comply with the stringent requirements of the Stage 2 D/DBP Rule. Ozonation is one of the available alternatives. Therefore, the findings will be important for utilities considering ozonation. The knowledge from this work will improve our understanding of the nature of HNM and nitrosamine formation and directly impact practitioner?s ability to control the formation of these compounds in treatment facilities. The USEPA and state regulatory agencies can benefit from the results in developing both present and future procedures for managing these compounds. Implementing this project will also promote training and education of a wide range of students with diverse backgrounds and levels. The PI will offer a Creative Inquiry research course through this project, a unique program of Clemson University bringing undergraduate students from different departments studying various disciplines to work in small team-projects and earn college credits. Participating students will learn about water treatment processes, applied chemistry (i.e., DPB formation) and how to conduct scientific research. The project will also allow opportunities for high school and undergraduate students, particularly from underrepresented groups.