Assessment of scale formation and corrosion of drinking water supplies in Ilam city (Iran)

Abstract

Background: Scaling and corrosion are the two most important indexes in water quality evaluation. Pollutants are released in water due to corrosion of pipelines. The aim of this study is to assess the scale formation and corrosion of drinking water supplies in Ilam city (Iran). Methods: This research is a descriptive and cross-sectional study which is based on the 20 drinking water sources in Ilam city. Experiments were carried out in accordance with the Water and Wastewater Co. standard methods for water and wastewater experiment. The data were analyzed by using Microsoft Excel and GraphPad Prism 5. The results were compared with national and international standards. Results: The mean and standard deviation (SD) values of Ryznar, Langelier, Aggressive, Puckorius and Larson-Skold indices in year 2009 were equal to 7.833 (±0.28),-0.102 (±0.35), 11.88 (±0.34), 7.481 (±0.22) and 0.801 (±0.44), respectively, and were 7.861 (±0.28),-0.175 (±0.34), 11.84 (±0.37), 7.298(±0.32) and 0.633 (±0.47), for year 2013 respectively. The average of Langelier, Ryznar, Aggression, and Puckorius indices indicate that potable water resources in Ilam city have the tendency to be corrosive. Statistical analysis and figures carried out by GraphPad Prism version 5.04. Conclusion: The results of different indices for water resources of Ilam city revealed that water supplies of Ilam city were corrosive. Water quality control and replacement of distribution pipes in development of water network should be carried out. Moreover, water pipelines should be preserved with several modes of corrosion inhibition. Introduction Corrosion is the physical-chemical interaction between the metal and its surroundings which is usually electro-chemical in nature and can lead to a change in the metal properties (1,2). The corrosion tends to release the metal pipe particles into the fluids. If the corrosion occurs quickly , it forms a hole and then perforation of pipes which is considered as a path for water contamination in a state of negative suction; but if the water has a tendency to scaling , the diameter of pipe will reduce over the time due to the formation of sediments layers in the inner part of the pipes which ultimately results to the reduction of flow rate (2-4). Unfortunately, there are no precise figures of corrosion and scaling damages in the Iran; nevertheless, the surveys indicate that 30% of treated water losses is related to decays of pipelines caused by the corrosion which also reduce the shelf life of sanitary equipment (4,5). So far,