The bulk chlorine decay rate in drinking water supply systems depend on many factors, including temperature. In this document, the method to determine the order of reaction of chlorine with water is reported, as well as the method to estimate Kb (Bulk reaction rate constant). Experiments were carried out to determine the bulk chlorine decay, for which a set of water samples to determine the free residual chlorine every hour were analyzed. Chlorine concentrations were graphed against time and adjusted appropriately to the developed model. The experimental results showed that the average value of the mass decomposition rate was 0.15 h −1 . It was shown that temperature affects the variation of the reaction rate of chlorine with water, Kb increases as temperature increases. In this manuscript it is reported: The method that allows determining the reaction kinetic order of chlorine with drinking water. The method that can help residual chlorine modelers in the correct definition of the bulk reaction rate constant. The effectiveness of the method for evaluating the decomposition of residual chlorine in drinking water distribution networks as a function of temperature.

The quality of drinking water flowing in a distribution network can possess corrosive characteristics that may cause the material degradation of pipes and accessories. This problem can result in reduction of the service life of pipes and create a major public health problem. The agreement between the physical-chemical water quality analysis and national standards are not enough to confirm the balance of the water quality in terms of corrosion. In order to predict pipe corrosion in water distribution system networks, the corrosive trend was evaluated using the Langelier (LSI), Ryznar (RSI), and Larson-Skold (LRI) indexes based on measurements of pH, temperature, total dissolved solids, alkalinity, calcium hardness, sulfate and chloride. This study was setup with 180 samples collected in six zones of the distribution network, from July to December of 2017, according to the standard methods for the analysis of drinking water.  The results indicate a variation of the LSI from -1.22 to -1.68; RSI from 9.75 to 10.52 and LRI from 0.46 to 0.77. A linear model was fitted for each index to predict the corrosion with the water quality conditions of this study case. Therefore, the drinking water of the city of Azogues, Ecuador has a corrosive tendency from significant to severe. Corrosion indices were calculated to provide useful information on the water's corrosiveness. These results indicate the need to constantly monitor the corrosion rate in the distribution network and conduct a laboratory study to adjust effective parameters such as pH, in order to control corrosion.

No abstract

Copper pipes corrosion that transport potable water can deteriorate water quality within a distribution system, releasing high copper amounts, exceeding the maximum concentration copper for potable water standards. This study examines the influence of free chlorine on the leaching of copper in the pipes used for the distribution of drinking water. A series of tests was carried out using corrosion test coupons extractable constructed of copper material. The coupons were installed in units containing filtered water (without chlorine, 0 mg/L) and water treated with an average residual chlorine concentration of 0.85 mg/L in the water treatment plant in Azogues city, Ecuador. A corrosion test rack was also installed in a house with an average residual chlorine concentration of 0.37 mg/L. Coupons in these sites were exposed in duplicate for one, two, three and six months. The corrosion coupons were then extracted and weighed to establish the corrosion rate by gravimetric technique. Additional tests were performed in static immersion laboratory tests using drinking water with chlorine concentrations ranging from 0.25 to 5 mg/L for one month. The weight loss tests indicated that an increase in free chlorine concentration, the greater release of copper and therefore a higher corrosion rate.

No abstract