International Science and Technology Journal

Quality of water is often measured by the residual amount of chlorine in a distribution system. Therefore, it is necessary to define the decay process of the disinfectant agent to come up with initial dose of chlorine. The big challenge is how to maintain concentration of chlorine within recommended range (0.2 – 0.5 mg/l) in whole system and all time. Therefore, determining a required initial concentration of chlorine that should be given to a system to maintain chlorine concentration within allowable limits throughout whole system is not an easy task. This paper aimed to determine the initial concentration of chlorine that must be pumped into the Benghazi water network in order to maintain its quality. To achieve this goal, a hydraulic model was constructed using the EPANT simulator. Where all elements of the network were represented, including the age of the pipes. Accordingly the optimal initial concentration of chlorine was determined (4 mg/l), which gives residual values of chlorine close to the values obtained from the laboratory, and by plotting the logarithm of these values with the logarithm of the optimal initial concentration, the decay rate was found equal to -0.055 1/day.