Relationship between chlorine decay and temperature in the drinking water

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.