Martinez Paz Ernesto F, Raskin Lutgarde, Wigginton Krista R, Kerkez Branko
Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Ave., 2044 GG Brown, Ann Arbor, MI 48109, USA.
Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Ave., 2044 GG Brown, Ann Arbor, MI 48109, USA.
Water Res. 2024 Mar 1;251:121098. doi: 10.1016/j.watres.2023.121098. Epub 2023 Dec 31.
Manual flushing of building plumbing is commonly used to address water quality issues that arise from water stagnation. Autonomous flushing informed by sensors has the potential to aid in the management of building plumbing, but a number of knowledge gaps hinder its application. This study evaluates autonomous flushing of building plumbing with online sensor and actuator nodes deployed under kitchen sinks in five residential houses. Online oxidation-reduction potential (ORP) and temperature data were collected for nine weeks during the winter and summer in houses with both free chlorine and chloramine. ORP levels in houses with free chlorine residuals decreased after overnight stagnation. The overnight decrease in ORP was not observed when tap water was automatically flushed for five minutes at 6:00 h every morning. ORP levels in houses with chloramine residuals did not decrease consistently after overnight stagnation, and daily automated flushes did not have an observable effect on the ORP signals. Additional laboratory experiments were carried out to evaluate ORP signals during chlorine decay and after incremental changes in chlorine, as would be expected in building plumbing conditions. Results from the lab and field deployments suggest on-line ORP sensors may be used to detect free chlorine decay due to stagnating water, but are not as effective in detecting chloramine decay. However, field results also suggest ORP may not respond as expected on a timely manner after free chlorine or chloramine have been restored, hindering their applicability in developing control algorithms. In this paper we tested twice-daily five-minute automatic flushing and found that it counteracts water quality degradation associated with overnight stagnation in free chlorine systems. An automatic sensor-based flushing is proposed using online temperature sensor data to determine when flushing has reached water from the main. The results suggest that flushing informed by temperature sensors can reduce the flushing time by 46 % compared to the preset five-minute static flush.
手动冲洗建筑物管道系统通常用于解决因水停滞而产生的水质问题。基于传感器的自动冲洗有潜力辅助建筑物管道系统的管理，但一些知识空白阻碍了其应用。本研究评估了在五所住宅的厨房水槽下方部署在线传感器和执行器节点对建筑物管道系统进行的自动冲洗。在冬季和夏季，对同时使用游离氯和氯胺的房屋收集了九周的在线氧化还原电位（ORP）和温度数据。有游离氯残留的房屋中，过夜停滞后ORP水平下降。当每天早上6点自动冲洗自来水5分钟时，未观察到ORP的过夜下降。有氯胺残留的房屋中，过夜停滞后ORP水平并非持续下降，每日自动冲洗对ORP信号没有明显影响。还进行了额外的实验室实验，以评估建筑物管道条件下氯衰减期间和氯增量变化后的ORP信号。实验室和现场部署的结果表明，在线ORP传感器可用于检测因水停滞导致的游离氯衰减，但在检测氯胺衰减方面效果不佳。然而，现场结果还表明，在游离氯或氯胺恢复后，ORP可能无法及时按预期响应，这阻碍了它们在开发控制算法中的应用。在本文中，我们测试了每天两次、每次5分钟的自动冲洗，发现它可以抵消游离氯系统中与过夜停滞相关的水质恶化。提出了一种基于自动传感器的冲洗方法，利用在线温度传感器数据来确定冲洗何时到达主管道的水。结果表明，与预设的5分钟静态冲洗相比，基于温度传感器的冲洗可将冲洗时间减少46%。
