Change regularity of water quality parameters in leakage flow conditions and their relationship with iron release. (1st November 2017)

• Record Type: Journal Article
• Authors: Liu, Jingqing; Shentu, Huabin; Chen, Huanyu; Ye, Ping; Xu, Bing; Zhang, Yifu; Bastani, Hamid; Peng, Hongxi; Chen, Lei; Zhang, Tuqiao
• Is Part Of: Water research. Volume 124(2017)
• Page Start: 353
• Page End: 362
• Publication Date: 2017-11-01
• Subjects: Metal pipe -- Leakage flow rate -- Iron release -- Water quality index -- Critical laminar flow velocity; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.07.027
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: The long-term stagnation in metal water supply pipes, usually caused by intermittent consumption patterns, will cause significant iron release and water quality deterioration, especially at the terminus of pipelines. Another common phenomenon at the terminus of pipelines is leakage, which is considered helpful by allowing seepage of low-quality drinking water resulting from long-term stagnation. In this study, the effect of laminar flow on alleviating water quality deterioration under different leakage conditions was investigated, and the potential thresholds of the flow rate, which can affect the iron release process, were discussed. Based on a galvanized pipe and ductile cast iron pipe pilot platform, which was established at the terminus of pipelines, this research was carried out by setting a series of leakage rate gradients to analyze the influence of different leakage flow rates on iron release, as well as the relationship with chemical and biological parameters. The results showed that the water quality parameters were obviously influenced by the change in flow velocity. Water quality was gradually improved with an increase in flow velocity, but its change regularity reflected a diversity under different flow rates ( p < 0.05). The iron release was remarkably correlated to the redox potential, dissolved oxygen, pH, iron-oxidized bacteria and sulfate-reducing bacteria. The cumulative total iron release ( r = 0.587, p < 0.05) and total iron release rate ( r = 0.71, p < 0.022) were significantly influenced by the changes in flow velocity. In short, they tended first to increase and then to decrease with an increasing flow velocity with the threshold as approximately 40% of the critical laminar flow velocity (1.16 × 10 −3 m/s). For the pipes at the terminus of the drinking water distribution system, when the bulk water was at the critical laminar flow velocity, the concentration of total iron, the quantity and rate of total iron release remain relatively in an ideal and safe situation. Graphical abstract: Highlights: Pilot experimental platform was located in a real drinking water distribution system. Flow velocity threshold effecting iron release under laminar flow was investigated. Total iron release and chemical-microbial indicators was investigated. The impact of different leakage flow rates on iron release in metal pipes.