低压瞬变可能是侵入管道的机制 微生物污染物进入分配系统。先前的研究 已经证明在饮酒时会出现负压（-16磅/平方英寸） 计划内或计划外停泵后的水系统。 这张海报纸模拟了感染病毒的风险 这些负压事件并评估缓解方案。A. 开发了定量微生物风险评估（QMRA）模型 未经治疗人群中诺沃克病毒和轮状病毒浓度的估计 污水排放基于对审查后公布值的蒙特卡罗分析。 可能侵入系统的污水量是基于 关于负压持续时间的对数分布 瞬变和配电泄漏的估计。 稀释 根据入侵量的分布计算入侵量 并导致对最终病毒的估计 浓度诺沃克病毒和轮状病毒的剂量反应数据 使用已知的耗水量估算值进行估算 基于客户分布的感染风险（需求） 在系统内部。敏感性分析表明，该方法的一致性 消耗量（消耗受污染液体的可能性） 水）对风险的影响最大，且与 负压事件的持续时间。消毒剂的估计 因侵入稀释污水和病毒灭活而产生的需求， 结果表明，游离氯残留的维持几乎消除 尽管存在风险，但病毒在人体内持续了24小时以上 氯胺化系统。未受影响系统中的单个事件 可能造成重大风险（>1/10000年感染风险），但 电力中断的数据显示，水泵停止运行 可能每月发生一次。总体而言，QMRA 该模型有助于组织已知数据，估计数据差距， 并为未来的研究检验假设。

Low pressure transients can be mechanisms for intrusion of microbial contaminants into the distribution system. Prior research has demonstrated episodes of negative pressure (-16 psi) in drinking water systems following planned or unplanned pump shutdowns. This poster paper models the risk of infection from these negative pressure events and evaluates mitigation options. A quantitative microbial risk assessment (QMRA) model developed estimates of norovirus and rotavirus concentrations in untreated sewage based on a Monte Carlo analysis of censored published values. The volume of sewage that could intrude into the system was based on a logarithmic distribution of the duration of negative pressure transients and an estimate of the distribution leakage. The dilution of the intrusion volume was calculated based on the distribution of flow in the system and resulted in an estimation of the final virus concentration. Dose response data for norovirus and rotavirus along with known estimates of water consumption were used to estimate the risk of infection based on the distribution of customers (demand) within the system. Sensitivity analysis showed that the coincidence of consumption (the probability of consuming the slug of contaminated water) has the strongest influence on risk and was related to the duration of the negative pressure event. Estimates of the disinfectant demand due to the intruded diluted sewage, and virus inactivation, showed that maintenance of free chlorine residuals nearly eliminated the risk, but viruses persisted for more than 24 hours in chloraminated systems. A single event in an undisinfected system could pose significant risk (>1/10,000 annual risk of infection), but data on electrical power interruptions showed that pump shutdowns could happen as frequently as once per month. Overall the QMRA model was useful for organizing known data, estimating data gaps, and testing hypotheses for future research.