As many regions seek to supplement traditional water sources with reclaimed water, an increasing number of risk assessments are conducted for these types of applications. The most comprehensive approach is to conduct a quantitative microbial risk assessment (QMRA) combining empirical and literature data, point value estimates, and probability distribution functions (PDFs) to estimate the final risk for human health from a treatment train in quantitative terms. The variability and uncertainty of reuse systems can be more adequately assessed by probabilistic methods instead of deterministic, point value estimates. This review summarizes common assumptions in PDF selection for source water and treatment steps and dose-response models for risk assessments applied to potable and non-potable reuse scenarios. The review revealed that source water pathogen concentrations were mainly modeled using PDFs, while log reduction values (LRVs) were often derived as point estimates to describe removal efficacy of individual treatment steps. When enough point value LRVs are known, a triangular distribution is recommended to retain the stochastic characteristics of the variable being modeled. Treatment steps with the least amount of experimental data included biological activated carbonand membrane bioreactors, among others. To circumvent such lack of experimental data, an open-source, anonymized database of concentrations and LRVs could be made available for future assessments. Numerous studies mentioned that testing multiple dose-response models can help determine how the dose-response choice affects final risk. Although sensitivity analyses to determine how variables in the assessment influence final risk were performed in most studies, how PDF selection affects the final risk was not consistently evaluated. Such a discussion could help to establish more informative and comprehensive risk assessment models in future studies as the water reuse field continues to grow.

随着许多地区寻求用再生水补充传统水源，针对这些类型的应用进行了越来越多的风险评估。最全面的方法是结合经验数据和文献数据，点值估计值和概率分布函数（PDF）进行定量微生物风险评估（QMRA），以量化的方式评估治疗方案对人类健康的最终风险。重用系统的可变性和不确定性可以通过概率方法而不是确定性的点值估计来更充分地评估。这篇综述总结了用于饮用水和非饮用水回用方案的水源和处理步骤的PDF选择中的常见假设以及用于风险评估的剂量响应模型。审查表明，水源病原体浓度主要使用PDF建模，而对数减少值（LRV）通常作为点估计值来描述单个处理步骤的去除效果。当已知足够的点值LRV时，建议采用三角分布以保留要建模的变量的随机特征。实验数据最少的处理步骤包括生物活性炭和膜生物反应器等。为了避免缺乏实验数据，可以提供一个开源的浓度和LRV匿名数据库，以供将来评估。许多研究提到测试多个剂量反应模型可以帮助确定剂量反应选择如何影响最终风险。尽管在大多数研究中都进行了敏感性分析来确定评估中的变量如何影响最终风险，但是并没有一致地评估PDF选择如何影响最终风险。随着中水回用领域的不断发展，这种讨论将有助于在未来的研究中建立更多信息丰富且全面的风险评估模型。