Hill Tyler, Wang Phillip, Olivieri Adam, Batista Jacimaria, Gerrity Daniel
Southern Nevada Water Authority, P.O. Box 99954, Las Vegas, NV 89193, United States; University of Nevada Las Vegas, Department of Civil & Environmental Engineering and Construction, 4505 S. Maryland Parkway, Las Vegas, NV 89154, United States.
Southern Nevada Water Authority, P.O. Box 99954, Las Vegas, NV 89193, United States.
Water Res. 2025 Mar 1;271:122886. doi: 10.1016/j.watres.2024.122886. Epub 2024 Nov 29.
Regulatory frameworks for potable reuse often include stringent log reduction value (LRV) targets to ensure public health protection against exposure to viruses and protozoa. To achieve overall LRV targets and reduce associated capital and operational costs, it is important to maximize LRV credits awarded to each unit process in a potable reuse treatment train. This may include processes that are historically uncredited or undercredited, such as secondary biological wastewater treatment incorporating activated sludge and secondary clarification. To identify gaps in knowledge and inform future efforts to justify virus crediting, this systematic literature review and meta-analysis focused on characterizing virus attenuation during secondary treatment and identifying any virus characteristics, operational conditions, or water quality parameters that could serve as predictors of virus LRVs. Out of a total of 1,341 search results from three databases, this review considered 44 peer-reviewed studies that met the criteria for inclusion. LRVs as high as 5.3 log were reported for F-specific coliphages, but some studies reported increases in rotavirus and norovirus GI concentrations across secondary treatment. Median LRVs ranged from 0.8 log for rotavirus and norovirus GI (both based on molecular methods) to 2.4 to 3.4 log for poliovirus (culture) and polyomavirus (molecular), respectively. 5 percentile LRVs were <1.0 log for multiple viruses. Study publication date was shown to have a significant impact, pooled virus LRVs exhibited a moderately strong correlation with reduction in biochemical oxygen demand (BOD), and mixed liquor suspended solids (MLSS) concentration demonstrated a threshold (∼1000 mg/L) beyond which there was no discernible relationship with virus LRV. In general, the lack of reported background data hindered identification of critical parameters that could inform model development or serve as surrogates for estimating virus LRV. More robust datasets that simultaneously evaluate a range of viruses and operational/water quality parameters are needed before LRV credits can be broadly and confidently awarded to conventional secondary biological wastewater treatment systems.
饮用水回用的监管框架通常包括严格的对数去除率（LRV）目标，以确保公众健康免受病毒和原生动物暴露的影响。为了实现总体LRV目标并降低相关的资本和运营成本，重要的是在饮用水回用处理流程中最大化分配给每个单元过程的LRV信用。这可能包括历史上未获信用或信用不足的过程，例如包含活性污泥和二次澄清的二级生物废水处理。为了识别知识空白并为未来证明病毒信用的努力提供信息，本系统文献综述和荟萃分析专注于表征二级处理过程中的病毒衰减，并识别任何可作为病毒LRV预测指标的病毒特征、运行条件或水质参数。在来自三个数据库的总共1341条搜索结果中，本综述考虑了44项符合纳入标准的同行评审研究。F特异性大肠杆菌噬菌体的LRV高达5.3个对数，但一些研究报告称，在二级处理过程中轮状病毒和诺如病毒GI浓度有所增加。轮状病毒和诺如病毒GI的中位数LRV（均基于分子方法）为0.8个对数，脊髓灰质炎病毒（培养法）和多瘤病毒（分子法）的中位数LRV分别为2.4至3.4个对数。多种病毒的第5百分位数LRV小于1.0个对数。研究发表日期显示有显著影响，汇总的病毒LRV与生化需氧量（BOD）的降低呈现中等强度的相关性，混合液悬浮固体（MLSS）浓度显示出一个阈值（约1000mg/L），超过该阈值后与病毒LRV没有明显关系。总体而言，缺乏报告的背景数据阻碍了对关键参数的识别，这些参数可为模型开发提供信息或作为估计病毒LRV的替代指标。在能够广泛且自信地将LRV信用授予传统二级生物废水处理系统之前，需要更强大的数据集同时评估一系列病毒以及运行/水质参数。
