Office of Research and Development, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA.
Soller Environmental, LLC, 3022 King St., Berkeley, CA 94703, USA.
Water Res. 2023 Apr 15;233:119742. doi: 10.1016/j.watres.2023.119742. Epub 2023 Feb 15.
Onsite non-potable water systems (ONWS) collect and treat local source waters for non-potable end uses such as toilet flushing and irrigation. Quantitative microbial risk assessment (QMRA) has been used to set pathogen log-reduction targets (LRTs) for ONWS to achieve the risk benchmark of 10 infections per person per year (ppy) in a series of two efforts completed in 2017 and 2021. In this work, we compare and synthesize the ONWS LRT efforts to inform the selection of pathogen LRTs. For onsite wastewater, greywater, and stormwater, LRTs for human enteric viruses and parasitic protozoa were within 1.5-log units between 2017 and 2021 efforts, despite differences in approaches used to characterize pathogens in these waters. For onsite wastewater and greywater, the 2017 effort used an epidemiology-based model to simulate pathogen concentrations contributed exclusively from onsite waste and selected Norovirus as the viral reference pathogen; the 2021 effort used municipal wastewater pathogen data and cultivable adenoviruses as the reference viral pathogen. Across source waters, the greatest differences occurred for viruses in stormwater, given the newly available municipal wastewater characterizations used for modeling sewage contributions in 2021 and the different selection of reference pathogens (Norovirus vs. adenoviruses). The roof runoff LRTs support the need for protozoa treatment, but these remain difficult to characterize due to the pathogen variability in roof runoff across space and time. The comparison highlights adaptability of the risk-based approach, allowing for updated LRTs as site specific or improved information becomes available. Future research efforts should focus on data collection of onsite water sources.
现场非饮用水系统 (ONWS) 收集和处理当地水源，用于非饮用水用途，如冲洗厕所和灌溉。定量微生物风险评估 (QMRA) 已被用于为 ONWS 设置病原体对数减少目标 (LRT)，以实现 2017 年和 2021 年完成的两项工作中的 10 个人/年感染风险基准 (ppy)。在这项工作中，我们比较和综合了 ONWS LRT 工作，以提供病原体 LRT 选择的信息。对于现场废水、灰水和雨水，2017 年和 2021 年的人类肠道病毒和寄生原生动物 LRT 相差 1.5 个对数单位，尽管这些水中病原体的特征方法不同。对于现场废水和灰水，2017 年的工作使用基于流行病学的模型来模拟仅由现场废物贡献的病原体浓度，并选择诺如病毒作为病毒参考病原体；2021 年的工作使用城市废水病原体数据和可培养腺病毒作为参考病毒病原体。在所有水源中，雨水病毒的差异最大，这是由于 2021 年新可用的城市废水特征化模型用于模拟污水贡献，以及不同的参考病原体选择（诺如病毒与腺病毒）。屋顶径流 LRT 支持原生动物处理的需求，但由于屋顶径流在空间和时间上的病原体变化，这些仍然难以表征。该比较突出了基于风险的方法的适应性，允许在获得更多关于特定地点或改进的信息时更新 LRT。未来的研究工作应侧重于现场水源的数据收集。
