Quantification of Unintentional Water Recycling in Surface Waters

[0303627]赛德拉克分析化学的最新进展已经导致在城市污水排放中检测到许多以前被忽视的化学污染物。虽然这些废水产生的污染物的存在导致对使用经过高度处理的废水来增加供水的项目进行相当严格的审查，但对无意中回收废水的问题却很少注意。20世纪70年代进行的一项调查结果表明，在一年中的某些时候，超过770万美国居民的水源含有超过50%的废水排放。由于人口持续增长，特别是在干旱地区，目前接受受废水影响的水的人数可能会更高。由于许多废水产生的污染物在水处理过程中没有被去除，这一途径可能导致大量人口暴露于致癌物质或内分泌干扰物的化学物质中。本项目的目标是评估目前无意中回收废水的程度，并开发可用于评估供水中废水衍生污染物潜在存在的工具。这些目标将通过水文模拟和实地测量相结合来实现。在项目的第一阶段，将确定可能发生意外回收的地点，并在地表水的条件下评估一套保守和反应性示踪剂。水文分析将包括估计在平均和低流量条件下在饮用水进水口流出的废水的比例，以及水在抽取之前在河流中度过的时间。在此初步分析的基础上，将在项目的第二阶段选择三个地点进行进一步分析。在每个站点，水文模型将使用特定站点的数据进行改进，包括河流形态、降水和污染物衰减率。该模型的预测结果将与在整个流域贡献地区的各个地点进行的保守示踪剂和反应示踪剂的测量结果进行比较。模型预测和测量之间的差异将用于改进模型并获得对污染物衰减率的更好估计。更广泛的影响除了对无意中回收废水所带来的风险提供新的见解外，该项目还将为来自代表性不足群体的学生提供新的研究机会，从而对科学和工程产生广泛的影响。在研究的第一阶段，来自表现不佳的当地学校的高中生将协助收集所需的数据，以确定无意回收的重要地点。在项目的第二阶段，来自代表性不足群体的本科生将协助实地工作和数据分析。

0303627 Sedlak Recent advances in analytical chemistry have led to the detection of numerous previously ignored chemical contaminants in municipal wastewater effluent. While the presence of these wastewater-derived contaminants has led to considerable scrutiny of projects in which highly treated wastewater is used to augment water supplies, little attention has been paid to the unintentional recycling of wastewater effluent. Results of a survey conducted during the 1970s suggested that over 7.7 million U.S. residents receive water from sources that consist of more than 50% wastewater effluent during some portion of the year. As a result of continued population growth, especially in arid regions, it is likely that the current number of people receiving wastewater-impacted water is even higher. Because many wastewater-derived contaminants are not removed during water treatment, this pathway could result in exposure of large populations to chemicals that are carcinogens or endocrine disrupters.Intellectual MeritThe objective of this project is to assess the current extent of unintentional recycling ofwastewater effluent and to develop tools that can be used to assess the potential presence of wastewater-derived contaminants in water supplies. These objectives will be accomplished through a combination of hydrologic modeling and field measurements. In the first phase of the project, locations where unintentional recycling is likely to be significant will be identified and a suite of conservative and reactive tracers will be evaluated under conditions found in surface waters. The hydrologic analysis will include estimation the fraction of wastewater effluent at drinking water intakes during average and low-flow conditions and the amount of time the water has spent in the river prior to abstraction. On the basis of this preliminary analysis, three sites will be chosen for further analysis during the second phase of the project. At each site, the hydrologic model will be refined using site-specific data including river morphology, precipitation and contaminant attenuation rates. Predictions from the model will be compared with measurements of conservative and reactive tracers made at locations throughout the contributing areas of the watershed. Discrepancies between model predictions and measurements will be used to refine the models and to obtain a better estimate of contaminant attenuation rates.Broader ImpactsIn addition to providing new insight into the risks posed by the unintentional recycling ofwastewater effluent, the project will have a broad impact on science and engineering byproviding new research opportunities for students from underrepresented groups. During the first phase of the research, high school students from low-performing local schools will assist in the collection of data needed to identify sites where unintentional recycling is significant. During the second phase of the project, undergraduate students from underrepresented groups will assist in field work and analysis of data.