Water quality effects of intermittent water supply in Arraijan, Panama
Water quality effects of intermittent water supply in Arraijan, Panama
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DOI：
10.1016/j.watres.2017.02.009
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发表时间：
2017-05-01
期刊：
影响因子：
12.8
通讯作者：
Nelson, Kara L.
中科院分区：
文献类型：
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作者：
Erickson, John J.;Smith, Charlotte D.;Nelson, Kara L.
间歇性饮用水供应在世界各地的低收入和中等收入国家很常见，可能导致供水系统的水质下降。在这项研究中，我们的特点是水质在一个研究区，连续供应和三个区，间歇性供应的饮用水分配网络在Arraijan，巴拿马。所有区域均出现低压或零压力，连续区域和两个间歇区域出现负压。尽管水力条件造成回流和污染物侵入的风险，但在随机收集的423个（0.9%）抓取样本中，只有4个（0.9%）对总大肠菌群呈阳性，只有1个对E。杆菌496个样品中只有9个（1.8%）浊度>1.0 NTU，所有样品的游离余氯均>0.2 mg/L。相比之下，水质往往在第一次冲洗期间（当供水在停电后第一次恢复时）下降。尽管如此，Arraijan在间歇性供应下的常规和首次冲洗水质比先前在印度进行的一项研究中报告的要好得多。Arraijan的水质更好可能是由于离开处理厂的水质更好，供水中断时间更短，供水压力更高，氯残留量更一致和更高，以及管道附近的污染源更少。结果表明，间歇性供水及其对水质的影响可以有很大的不同之间和内部的分配网络。该研究还表明，专门为间歇性供水设计的监测技术，如连续压力监测和首次冲洗取样，可以检测到水质威胁和退化，这是传统监测不可能检测到的。(C)2017爱思唯尔有限公司版权所有。
Intermittent drinking water supply is common in low- and middle-income countries throughout the world and can cause water quality to degrade in the distribution system. In this study, we characterized water quality in one study zone with continuous supply and three zones with intermittent supply in the drinking water distribution network in Arraijan, Panama. Low or zero pressures occurred in all zones, and negative pressures occurred in the continuous zone and two of the intermittent zones. Despite hydraulic conditions that created risks for backflow and contaminant intrusion, only four of 423 (0.9%) grab samples collected at random times were positive for total coliform bacteria and only one was positive for E. coli. Only nine of 496 (1.8%) samples had turbidity >1.0 NTU and all samples had >0.2 mg/L free chlorine residual. In contrast, water quality was often degraded during the first-flush period (when supply first returned after an outage). Still, routine and first-flush water quality under intermittent supply was much better in Arraijan than that reported in a previous study conducted in India. Better water quality in Arraijan could be due to better water quality leaving the treatment plant, shorter supply outages, higher supply pressures, a more consistent and higher chlorine residual, and fewer contaminant sources near pipes. The results illustrate that intermittent supply and its effects on water quality can vary greatly between and within distribution networks. The study also demonstrated that monitoring techniques designed specifically for intermittent supply, such as continuous pressure monitoring and sampling the first flush, can detect water quality threats and degradation that would not likely be detected with conventional monitoring. (C) 2017 Elsevier Ltd. All rights reserved.