Corrosion and Scaling Potential in drinking water distribution system: a case study of Mashhad, 2017

Corrosion and Scaling in distribution network pipes is one of the most important indices in water quality evaluation and one of the most common environmental phenomena that deteriorate water quality, color, odor, taste and also increases the concentration of heavy metals in water. Corrosion causes entry of bye-products to water and decreases pipe life and sedimentation, reduces the flow rate and the efficiency of valves and fittings. The purpose of this study was to determine the corrosion or Scaling state of drinking water in Mashhad in 2017.
Material and In this study, 72 samples were taken during 2017 to evaluate water quality characteristics, and analyzed based on the standard methods. Then, three indices including Langlier, Ryznar and Aggressiveness Indices were programmed in Excel software and based on this, Corrosion and scaling potential of drinking water were determined. Results showed that the averages of Langlier, Ryznar and Aggressiveness Indices for water were 0.14±0.48, 6.67±0.38 and 12.23±0.23, respectively. According to the Langlier and Ryznar indices, 86.1% of total samples had low scaling potential and according to Aggressive index 97.2% of total samples had scaling. Also, the results showed that 58.33% of the samples were low scaling in spring and other samples were high scaling. In addition, in the summer, 33.3% of the total samples were high scaling and other samples were low scaling. The results showed that drinking water of Mashhad city was Scaling. Therefore, it is necessary to take measures to control scaling in distribution network pipes, especially in areas located in high scaling zones.