Use of oxidation-reduction potential to monitor iron release from corroded iron pipes in drinking water distribution system
JIANG Wei1, LIU Jing-qing1, YE Ping2, LI Hang-jia2
1. Municipal Engineering Research Institute, Zhejiang University, Hangzhou 310058, China; 2. Jiaxing Jiayuan Water Supply Company, Jiaxing 314000, China
Pipe scale samples were obtained from two pilot-scale drinking water distribution systems in an eastern city, and analyzed with SEM, EDS and XRD. Results indicate that physicochemical characteristics of two pipe scale are similar; Pipe scale surface is covered with shell-like layer; Major elements are Fe, O and C, and main substances are Fe3O4 and FeOOH. By pilot study, correlation between oxidation-reduction potential (ORP) and iron release in stagnant water was investigated in different seasons, and was compared with iron release correlations of dissolved oxygen (DO) and turbidity. Results show that although pipe scales characteristics are similar, changes in water quality during transmission can cause significant differences in iron release. Iron release from the same pipe was various in different seasons. ORP can be an indicator in predicting iron release. When ORP＞200 mV, iron release is governed and there is no dissolved iron release. When ORP＜200 mV, iron release severely and dissolved iron can release. ORP correlates iron release better than DO.
JIANG Wei, LIU Jing-qing, YE Ping, LI Hang-jia. Use of oxidation-reduction potential to monitor iron release from corroded iron pipes in drinking water distribution system. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2015, 49(4): 769-775.
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