Leifels Mats, Cheng Dan, Cai Jiawei, Nadhirah Nasha, Mohidin Abeed Fatima, Santillan Ezequiel, Woo Yissue, Hill Eric, Wu Sophia W, Boon Nico, Favere Jorien, Whittle Andrew J, Wuertz Stefan
Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.
Division of Water Quality and Health, Department of Pharmacology, Physiology and Microbiology, Karl Landsteiner University, Krems, 3500, Austria.
Sci Rep. 2025 Jul 1;15(1):22408. doi: 10.1038/s41598-025-03535-1.
Intermittent service provision (IWS) in piped drinking water distribution systems is practiced in countries with limited water resources; it leads to stagnant periods during which water drains completely from de-pressurized pipes, increasing the likelihood of biofilm detachment upon reconnection when water is supplied to the consumer and thus affecting water quality. Our study examines the impact of uninterrupted or continuous water supply (CWS) and IWS on microbial communities and biofilm detachment, using data from three 30-day experiments conducted in an above-ground drinking water testbed with 90-m long PVC pipes containing residual monochloramine. Flow cytometry (FCM) revealed a significant increase in total and intact cell concentrations when water was supplied intermittently compared to CWS, and the microbial alpha-diversity was significantly higher in CWS sections by both 16S rRNA gene metabarcoding and phenotypic fingerprinting of flow cytometry data. Nitrate levels in the water were significantly higher during initial intermittent flow due to the activity of nitrifying bacteria in biofilms exposed to stagnant water in pipes. Overall, biofilm detachment significantly affects the biological stability of drinking water delivered through IWS compared to CWS. We developed a novel biofilm detachment potential index derived from FCM data to estimate the minimum amount of water needed to be discarded before microbial cell counts and community composition return to baseline levels.
水资源有限的国家在管道饮用水分配系统中采用间歇性供水（IWS）；这会导致停滞期，在此期间水会从减压管道中完全排空，增加了重新供水给消费者时生物膜脱落的可能性，从而影响水质。我们的研究利用在一个地上饮用水试验台上进行的三项为期30天的实验数据，研究了不间断或连续供水（CWS）和间歇性供水对微生物群落和生物膜脱落的影响，该试验台有90米长的含残余一氯胺的PVC管道。流式细胞仪（FCM）显示，与连续供水相比，间歇性供水时总细胞浓度和完整细胞浓度显著增加，并且通过16S rRNA基因宏条形码分析和流式细胞仪数据的表型指纹分析，连续供水部分的微生物α多样性显著更高。由于管道中停滞水接触的生物膜中硝化细菌的活动，初始间歇流动期间水中的硝酸盐水平显著更高。总体而言，与连续供水相比，生物膜脱落显著影响通过间歇性供水输送的饮用水的生物稳定性。我们从流式细胞仪数据中开发了一种新的生物膜脱落潜力指数，以估计在微生物细胞计数和群落组成恢复到基线水平之前需要丢弃的最小水量。
