GOALI: WERF, WRF: Collaborative Research: Quantifying the Contribution of DBPs to the Toxicity of Wastewaters Purified for Potable Reuse: Which Byproduct Classes Matter?

合作提案编号：1706154/1706575PI名称：William Mitch/Michael Plewa美国干旱地区的人口不断增加，以及德克萨斯州和加利福尼亚州最近的干旱，人们对净化城市污水作为当地安全饮用水的兴趣日益浓厚。饮用水再利用项目的一个关键障碍是，公用事业公司、监管机构和公众对净化废水中化学物质对人类健康的影响始终存在不确定性。国家研究委员会指出，水和净化废水消毒的副产品（消毒副产品或DBPs）是人类健康风险的主要驱动因素；然而，DBP对整体毒性的贡献以及不同DBP类别的相对重要性尚未被量化。在本项目中，pi将量化不同DBP类别对消毒净化废水毒性的贡献，以确定哪些类别是毒性的最重要驱动因素。该项目的结果将提供关键数据，使监管机构能够评估饮用水再利用项目，并优先考虑化学污染物类别（特别是dbp）进行监管。本项目的主要假设是，经过高级处理的城市废水的总体毒性低于采用受废水影响（即事实上的再使用）的传统饮用水，甚至低于原始水源。为了验证这一假设，pi将从数量上比较一系列具有代表性的传统饮用水的毒性，这些饮用水要么使用原始水源，要么使用受废水影响的水源，要么使用与饮用水再利用操作相关的水源。比较将采用针对一系列相关终点（细胞毒性、遗传毒性和氧化应激）的体外定量生物测定。为了量化不同DBP类别对消毒饮用水的毒性的贡献，pi将比较消毒饮用水的体外生物测定反应与去离子水的体外生物测定反应，这些去离子水的浓度要么是在这些水中测量的所有DBP，要么是特定DBP类别的所有成员。DBP的研究集中于个别化学类别（例如亚硝胺），化学家和毒理学家通常分开工作。通过将广泛的DBP类别的化学分析与定量毒理学相结合，以确定驱动毒性反应的类别，pi期望这项工作的结果可以改变DBP研究的方法。这项工作还将解决DBP研究中两个长期存在的问题。首先，DBP混合物的毒性是否与添加剂有关，还是有协同作用或拮抗作用？这个问题将通过比较单个DBP类别与其混合物的生物测定反应来回答。其次，DBP的研究主要集中在低分子量物种上，一般只占有机卤素总量的~30-40%。高分子量dbp在多大程度上导致毒性？随着消毒剂应用于反渗透（RO）单元的上游，饮用水再利用列车是回答这个问题的理想选择。除了为研究生和本科生提供研究机会外，一名高中科学教师和一名未被充分代表的高中生将协助暑期研究，目的是在接下来的一年将这些材料纳入高中课程。

Collaborative Proposal Numbers: 1706154/1706575PI Names: William Mitch/Michael Plewa Increasing populations in arid regions of the US and recent droughts in Texas and California are increasing interest in purifying municipal wastewater as a local, secure supply for drinking water. A critical roadblock for potable reuse projects is lingering uncertainty among utilities, regulators, and the public regarding the human health impacts of chemicals in the purified wastewater. The National Research Council has indicated that byproducts of water and purified wastewater disinfection (disinfection byproducts or DBPs) are the predominant drivers of human health risks; however, the contribution to toxicity of DBPs as a whole and the relative importance of different DBP classes has not been quantified. In this project the PIs will quantify the contributions of different DBP classes to the toxicity of disinfected purified wastewaters to determine which classes are the most significant drivers of toxicity. Results from this project will provide critical data to enable regulators to evaluate potable reuse projects and to prioritize chemical contaminant classes (particularly DBPs) for regulatory oversight.In this project the main hypothesis is that advanced treated municipal wastewaters exhibit lower overall toxicity than conventional drinking waters employing wastewater-impacted (i.e., de facto reuse), or even pristine source waters. To test this hypothesis, the PIs will quantitatively compare the toxicity of a series of representative conventional drinking waters using either pristine or wastewater-impacted source waters with waters associated with potable reuse operations. The comparison will employ quantitative in vitro bioassays targeting a range of relevant endpoints (cytotoxicity, genotoxicity, and oxidative stress).To quantify the contributions of different DBP classes to the toxicity of disinfected potable reuse waters, the PIs will compare the in vitro bioassay responses of disinfected potable reuse waters to those of deionized water spiked with the concentrations of either all the DBPs measured in these waters, or all of the members of specific DBP classes. DBP research has focused on individual chemical classes (e.g., nitrosamines), with chemists and toxicologists often working separately. By integrating chemical analysis of a broad range of DBP classes with quantitative toxicology to identify the classes driving toxic responses, the PIs expect that results from this work could transform the approach to DBP research. This work will also address two long-standing questions for DBP research. First, is the toxicity associated with DBP mixtures additive or is there synergism or antagonism? This question will be answered by comparing the bioassay responses for individual DBP classes against their mixtures. Second, DBP research has focused on low molecular weight species, generally accounting for only ~30-40% of total organic halogen (TOX). To what extent do high molecular weight DBPs contribute to toxicity? With disinfectants applied upstream of reverse osmosis (RO) units, potable reuse trains are ideal for answering this question. In addition to the research opportunities afforded to graduate and undergraduate students, a high school science teacher and underrepresented high school student will assist in summer research, with an eye to incorporating this material into the high school curriculum over the following year.