The impact of sample line biofilms on drinking water quality and microbial compliance

设想了使用定制的全尺寸样品线测试台(重建操作系统的物理、化学和生物条件)的实验室测试和现场工作相结合的方式，以确保理解是可转移的。在不同的设计、运行和采样水力制度下，将监测样品线生物膜的形成、特性(微生物群、EPS、物理结构)和移动性(通过分析可拆卸表面)，以及总体水质和浮游微生物群。在谢菲尔德大学(UoS)温控管路设施中安装样品线钻机将提供实验室级别的控制，以确定诸如样品线材料/连接、水龙头清洗策略、液压操作(停滞/流动)和样品采集过程中的剪应力(冲洗制度)等变量的影响。UOS设置还将促进非致病性大肠菌群的尖峰测试，并将样品线生物膜与网络管道中形成的生物膜进行比较。了解和量化最终水的特性，如杀菌剂浓度和营养负荷(结合水力学)对样品线生物膜生长速度和稳定性的影响，将是指导最佳样品线设计和管理的关键。因此，除了实验室工作外，还将在水处理厂安装样机，由一家(或多家)自来水公司赞助。水力方案的子集将在广泛的处理水类型和水质上进行测试；季节性和/或位置(售货亭与房间)可以通过纵向研究来探索。一个典型的实验预计涉及在特定环境条件下形成生物膜，将生物膜暴露在采样过程中发生的不同水力干扰(冲洗)中，允许生物膜重新生长，然后重复冲洗制度。将定期收集生物膜和散装水样(在线和离散)，以确定细胞浓度、细胞活力、微生物群组成(特别是细菌和大肠菌群)和有针对性的生物膜物理结构分析(EPS)。从实验方案中获得的理解将通过分析历史上的细菌学超越数据集来探索所确定的重要环境因素与细菌学超越之间的相关性来验证。

A combination of laboratory tests and fieldwork using bespoke full-scale sample line testing rigs (recreating physical, chemical, and biological conditions of operational systems) is envisioned to ensure understanding is transferable. Sample line biofilm formation, characteristics (microbiome, EPS, physical structure) and mobilisation will be monitored (via the analysis of removable surfaces), alongside bulk-water quality and planktonic microbiome, under different design, operational and sampling hydraulic regimes. Installation of sample line rigs in The University of Sheffield (UoS) temperature-controlled pipe loop facility will provide laboratory level control to determine the impact of variables such as sample line material/connections, tap cleaning strategies, hydraulic operation (stagnation/flowing) and shear stress during sample collection (flushing regimes). The UoS setup would also facilitate spike tests with non-pathogenic coliforms and comparison of sample line biofilms to those forming in network pipes. Understanding and quantifying the impact of final water characteristics such as biocide concentration and nutrient loads (in combination with hydraulics) on sample line biofilm growth rate and stability will be key to informing optimal sample line design and management. Thus, lab work will be complemented by installation of sample line rigs at water treatment works, with one (or more) water company sponsors. A subset of hydraulic regimes will be tested across a wide range of treated water types and qualities; seasonality and/or location (kiosk vs. room) could be explored via a longitudinal study. A typical experiment is anticipated to involve developing biofilms under a particular environmental condition, exposing the biofilms to different hydraulic disturbances (flushing) as occurs during sampling, allowing the biofilms to regrow and then repeating the flushing regime. Regular biofilm and bulk-water samples (online and discrete) will be collected to characterise cell concentrations, cell viability, microbiome composition (particularly bacteria and coliforms) and targeted analysis of biofilm physical structure (EPS). The understanding gained from the experimental programme will be validated by exploration of the correlation between the identified important environmental factors and bacteriological exceedance through analysis of historic bacteriological exceedance datasets.