人口增长导致了水需求的增加和长期干旱 上游废水污染水源的条件 污水处理厂（WWTPs）促使许多供水商重新思考当前的问题 以及未来的水管理实践。现在，水供应商的数量超过了 面对日益减少的水资源供应和更大的 处理后的废水中有一小部分现在正被用于饮用水供应。 许多废水处理设施正在实践或探索各种技术 （例如，高级生物处理、膜、土壤含水层处理）作为 回收、再充电、回收和再利用（即直接使用）计划。 人们的注意力集中在药物和内分泌干扰物上，但WWTPs 如果需要氯消毒，也可能是消毒副产物（DBP）的来源 实践，和DBP先驱。运行条件、处理后的废水质量、命运和运输 接收体内的现象，以及污水处理厂排放的相对流量 对接收流的影响将决定废水产生的总体影响 饮用水供应的DBP。此外，人们对这一点知之甚少 如何最好地在WWTPs和DWTPs之间投资公共资金，以便 最大限度地提高社会效益，同时最大限度地降低 废水衍生的DBPs。 为了理解这些重要问题，进行了一项全面的研究。 来自世界各地的20多个污水处理厂和污水处理厂 美国参加了AWWA研究基金会赞助的一项研究 （AwwaRF）和美国环境保护局（USEPA）。成本效益 分析（CBA）是本研究的一部分。本文分阶段进行讨论 第二步，CBA的预测方法已经完成 DWTPs处的水DBPs水平，其水源受到处理过的污水的影响 废水。该方法包括按处理类型对废水进行详细描述，然后是命运和运输（以及 在DWTP处理之前，在接收体内进行稀释 评估DWTP和分布中形成的DBP数量 系统 为了预测废水处理后接收体内DBP前体水平， 开发并使用了几种命运和运输模型。这些模型 预测了生物降解对河流中DBP前体水平的影响。 这个 预测的DWTP进水水质随后与美国环保局的 水处理厂（WTP）模型，用于预测 受监管的DBPs（即三卤甲烷[THMs]和卤乙酸[HAAs]）在 工厂废水和分配系统中的废水。成本曲线也为 DWTPs和WWTPs在分配与不同 治疗类型。污水处理厂改善处理的成本与 DWTP或两者的组合，以确保DWTP的合规性 随着饮用水最大污染物水平（MCL）的不同 对上游污水处理厂的情况进行了评估。进行了CBA，包括 两种卤化DBP（即THMs、HAAs）以及非卤化DBP的控制 DBP（即N-亚硝二甲胺[NDMA]）。CBA模型旨在解决以下问题: 废水处理水平及其对出水水质的影响 （即污水处理厂的废水有机物[EfOM]）； 从污水处理厂向污水处理厂输送DBP前体（即:。， 排放到接收体及其稀释系数）以及 DBP前体的归宿和迁移（如生物降解）；DWTP使用的处理类型（例如，常规或高级 处理）及其去除DBP前体（即总 有机碳[TOC]、紫外线吸收[UVA]、溶解有机物 在污水处理厂消毒前的氮气[DON]；以及DWTP的消毒实践（即氯气和/或替代品） 消毒剂）及其对环境中形成的DBP类型和数量的影响 DWTP和

Population-growth-driven increased water demands and prolonged drought conditions along with source water contamination by upstream wastewater treatment plants (WWTPs) is prompting many water purveyors to rethink current and future water management practices. Water purveyors are now, more than ever, faced with the challenges of a dwindling water supply, and a greater fraction of treated wastewater is now finding its way to drinking water supplies. Many wastewater facilities are now practicing or exploring various technologies (e.g., advanced biological treatment, membranes, soil aquifer treatment) as part of reclamation, recharge, recycling, and reuse (i.e., direct use) programs. Attention has focused on pharmaceuticals and endocrine disruptors, but WWTPs are also sources of disinfection byproducts (DBPs), if chlorine disinfection is practiced, and DBP precursors. Operational conditions, treated wastewater quality, fate-and-transport phenomenon in the receiving body, and the relative flow of the WWTP discharge to that of the receiving stream will determine the overall impact of wastewater-derived DBPs on drinking water supplies. Moreover, very little is known about how best to invest public money between WWTPs and DWTPs in order to maximize societal benefits while minimizing the health risks posed by wastewater-derived DBPs. To understand these important issues, a comprehensive study was undertaken. More than 20 WWTPs and DWTPs from various geographical locations in the U.S. participated in a study sponsored by the Awwa Research Foundation (AwwaRF) and U.S. Environmental Protection Agency (USEPA). A cost benefit analyses (CBA) was performed as part of this study. This paper discusses, step by step, the approach to CBA in predicting finished water DBPs level at DWTPs whose source water is impacted by treated wastewater. The approach included a detailed characterization of the wastewater effluent by treatment type, followed by fate-and-transport (and dilution) in the receiving body prior to its treatment at the DWTP, and ultimately assessing the amount of DBPs to form at the DWTP and in the distribution system. To predict DBP precursor levels in receiving bodies after wastewater treatment, several fate-and-transport models were developed and used. These models predicted the impact of biodegradation on DBP precursor levels in a river. The predicted influent water quality to the DWTP was then used with the USEPA's Water Treatment Plant (WTP) model to predict finished water concentrations for regulated DBPs (i.e., trihalomethanes [THMs] and haloacetic acids [HAAs]) in the plant effluent and in the distribution system. Cost curves were also developed for both DWTPs and WWTPs in ascribing the costs associated with different treatment types. The cost of improved treatment at the WWTP versus at the DWTP or a combination of the two in order to ensure compliance at the DWTP with the drinking water maximum contaminant levels (MCLs) with various upstream WWTP scenarios was evaluated. A CBA was performed that included the control of both halogenated DBPs (i.e., THMs, HAAs) as well a nonhalogenated DBP (i.e., N-nitrosodimethylamine [NDMA]). The CBA model was developed to address the following issues: level of wastewater treatment and its impact on the effluent water quality (i.e., effluent organic matter [EfOM]) of the WWTP; conveyance of DBP precursors from the WWTP to the DWTP (i.e., discharge into a receiving body and its dilution factor) and the impact of fate and transport (e.g., biodegradation) on the DBP precursors; type of treatment used at the DWTP (e.g., conventional or advanced treatment) and its effectiveness in removing DBP precursor (i.e., total organic carbon [TOC], ultraviolet absorbance [UVA], dissolved organic nitrogen [DON]) prior to disinfection at the DWTP; and, disinfection practices at the DWTP (i.e., chlorine and/or alternative disinfectants) and its impact on the type and quantity of DBPs formed at the DWTP and in th