The Effects of Physicochemical Factors on Chlorine Decay in A Distribution Network

Abstract

In Korea, chlorine is used as a major disinfectant to control the microbial quality of drinking water and also as an indicator of water quality in a distribution network. It is generally accepted that a minimum chlorine concentration of 0.2 mg/L is required in the network to ensure the minimum safety of water. However, it is known that chlorine does not last long in the network because the water contains various chlorine-consuming materials. To effectively maintain the chlorine concentration above the required level, it is necessary to have a more detailed and comprehensive understanding of the physicochemical behavior of chlorine in a distribution network. In this work, we attempted to correlate chlorine decay to various chlorine consuming parameters in a network by means of several simulated distribution system (SDS) experiments and found that the initial chlorine concentration, temperature, total organic carbon (TOC) , velocity of flow, and contact time in drinking water are the physico-chemical factors affecting chlorine decay. The initial concentration of chlorine was positively related to the residual free chlorine, whereas other parameters, including the iron concentration, TOC, temperature, and retention time, were negatively related.