Reasons for High Chlorine Consumption under High Concentration of Ammonia Nitrogen in Raw Water and the Control Measures

A high concentration of ammonia nitrogen in raw water of Yuepu Water Treatment Plant, Shantou was observed for more than 10 days in the period of March to May in recent years. As a result, the chlorine consumption increased significantly. Factors affecting the high chlorine consumption were evaluated, including raw water quality, water treatment units, chlorine dosing methods and analysis methods of residual chlorine. Test results suggest that adding some calcium hypochlorite to each treatment unit periodically, using total chlorine instead of free chlorine to control the residual chlorine concentration, using the DPD method for residual chlorine detection can solve the problem of high chlorine consumption effectively.