Simulation of Chlorine Decay in Drinking-Water Distribution Systems

Abstract

In many water quality model applications to real networks, it has been observed that the chlorine concentrations at nodes on the secondary pipes with long residence times do not compare well with the model predictions. Therefore, it is important to better estimate the correct chlorine contents of outer nodes in order to determine the dosing time and the amount of chlorine during secondary chlorination. A model is developed for evaluating chlorine decay in drinking-water distribution networks. The model uses a simplified two-dimensional expression of a chlorine transport and decay equation within a single pipe that includes the bulk-flow reaction, radial diffusion, and pipe-wall reaction of chlorine. The computer program DYNAQ developed in this study, which tracks chlorine transport and decay using a time-driven approach, is also applied to the chlorine measurements taken from a portion of the South Central Connecticut Regional Water Authority’s service area. A comparison of the results of the model with those of a previously developed model is also included in this paper.