Schoen Mary E, Jahne Michael A, Garland Jay
Soller Environmental, LLC, 3022 King St., Berkeley, CA 94703, USA.
U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
Microb Risk Anal. 2018 Aug;9:72-81. doi: 10.1016/j.mran.2018.01.003.
We assessed the annual probability of infection resulting from non-potable exposures to distributed greywater and domestic wastewater treated by an aerobic membrane bioreactor (MBR) followed by chlorination. A probabilistic quantitative microbial risk assessment was conducted for both residential and office buildings and a residential district using , and spp. as reference pathogens. A Monte Carlo approach captured variation in pathogen concentration in the collected water and pathogen (or microbial surrogate) treatment performance, when available, for various source water and collection scale combinations. Uncertain inputs such as dose-response relationships and the volume ingested were treated deterministically and explored through sensitivity analysis. The predicted 95th percentile annual risks for non-potable indoor reuse of distributed greywater and domestic wastewater at district and building scales were less than the selected health benchmark of 10 infections per person per year (ppy) for all pathogens except spp., given the selected exposure (which included occasional, accidental ingestion), dose-response, and treatment performance assumptions. For spp., the 95th percentile annual risks for reuse of domestic wastewater (for all selected collection scenarios) and district-collected greywater were greater than the selected health benchmark when using the limited, available MBR treatment performance data; this finding is counterintuitive given the large size of spp. relative to the MBR pores. Therefore, additional data on MBR removal of protozoa is required to evaluate the proposed MBR treatment process for non-potable reuse. Although the predicted annual risks were small across scenarios (less than 10 infections ppy), the risks for remain uncertain, in part because the treatment performance is difficult to interpret given that the ratio of total to infectious viruses in the raw and treated effluents remains unknown. Overall, the differences in pathogen characterization between collection type (i.e., office vs. residential) and scale (i.e., district vs. building) drove the differences in predicted risk; and, the accidental ingestion event (although modeled as rare) determined the annual probability of infection. The predicted risks resulting from treatment malfunction scenarios indicated that online, real-time monitoring of both the MBR and disinfection processes remains important for non-potable reuse at distributed scales. The resulting predicted health risks provide insight on the suitability of MBR treatment for distributed, non-potable reuse at different collection scales and the potential to reduce health risks for non-potable reuse.
我们评估了因接触经好氧膜生物反应器（MBR）处理后再氯化的分散式中水和生活污水而导致感染的年概率。针对住宅和办公楼以及一个住宅区，以 、 和 属作为参考病原体进行了概率性定量微生物风险评估。对于各种水源和收集规模组合，蒙特卡罗方法捕捉了收集水中病原体浓度的变化以及病原体（或微生物替代物）的处理性能（若有）。剂量 - 反应关系和摄入量等不确定输入进行了确定性处理，并通过敏感性分析进行了探讨。在给定选定暴露（包括偶尔的意外摄入）、剂量 - 反应和处理性能假设的情况下，对于除 属之外的所有病原体，在区域和建筑规模上分散式中水和生活污水非饮用水室内再利用的预测第95百分位数年风险低于选定的每人每年10次感染（ppy）的健康基准。对于 属，在使用有限的可用MBR处理性能数据时，生活污水再利用（所有选定收集场景）和区域收集的中水的第95百分位数年风险大于选定的健康基准；鉴于 属相对于MBR孔隙的尺寸较大，这一发现有违直觉。因此，需要更多关于MBR去除原生动物的数据来评估提议的MBR非饮用水再利用处理工艺。尽管跨场景预测的 年风险较小（低于10次感染ppy），但 的风险仍然不确定，部分原因是由于原水和处理后废水中总病毒与感染性病毒的比例仍然未知，处理性能难以解释。总体而言，收集类型（即办公楼与住宅）和规模（即区域与建筑）之间病原体特征的差异导致了预测风险的差异；并且，意外摄入事件（尽管建模为罕见）决定了年感染概率。处理故障场景导致的预测风险表明，对于分散规模的非饮用水再利用，对MBR和消毒过程进行在线实时监测仍然很重要。由此产生的预测健康风险为MBR处理在不同收集规模下用于分散式非饮用水再利用的适用性以及降低非饮用水再利用健康风险的潜力提供了见解。
