Scale Formation and Corrosion of Drinking Water Pipes: A Case Study of Drinking Water Distribution System of Shiraz City

Abstract

<p>Due to increased consumption of drinking water in the world, there are attempts to apply new solutions for<br />accessing sufficient amounts of water with proper quality. In addition, efficient usage of energy and finding a<br />solution for reducing the scale-related problems in drinking water pipes are among major concerns of urban<br />water supply. Annually, significant budgets are assigned for removing the scale of pipes as well as home and<br />industrial devices. The present study endeavors to examine the scale-formation and corrosion potential of<br />drinking water in drinking water distribution network of Shiraz City (south of Iran). This study is of descriptive<br />type conducted through Langelier, Puckorius, Ryznar, Larson and aggressive indices and taking 144 samples of<br />different sources and points of distribution network. The results showed that the mean values of LI, RI, LS and<br />AI were 0.07 (slightly scale forming), 7.1 (non-scale forming), 1.2 (corrosive) and 14 (non-corrosive),<br />respectively. The mean of scale formation rate value in Shiraz drinking water pipes was 0.26 mm/y. Accordingly,<br />zones located in east, southeast and south of Shiraz have more problems of scale formation. Scale composition of<br />33 home pipe samples and 8 network pipe samples were analyzed by X-ray diffraction method. Results indicated<br />that main compositions in scale samples were calcium carbonate, calcium sulfate, magnesium carbonate,<br />magnesium sulfate, hematite, maghemite, magnetite, goethite, zinc oxide, gypsum, vivianite, dolomite,<br />hydroxyapatite and troilite. Main elements in scale samples were magnesium, silicon, phosphorus, sulfur, zinc,<br />copper and lead.</p>