EFFECTIVENESS OF CHLORINE AS DISINFECTANT FOR WASTEWATER

An investigation into the effectiveness of chlorine as disinfectant was conducted due to the problems experienced at the two Wastewater Treatment Plants operated by Sedibeng Water. Following the literature review, including research by Momba and co-workers (WISA, 2006), the investigation was structured to focus on the following aspects: • The effectiveness of chlorine as disinfectant • Factors affecting the efficiency of chlorine as disinfectant • Cost effective alternatives for chlorine The effect of Nitrogen, Chemical Oxygen Demand and Bacterial counts on dosing requirements and contact time, when using chlorine, were investigated. The results obtained from full scale monitoring were used as baseline information and reference for the rest of the study. Except for ozone, which could not be evaluated due to problems with instrumentation, all other disinfectants evaluated were found to be effective alternatives for chlorine. Cost finally remains the determining factor when deciding on any treatment option and such a decision will be enhanced by the knowledge and understanding of the process applied the environment and the quality of the final effluent from the plant. Although various options are available, some of which have been evaluated in this study, it could be concluded that chlorine remains a cost effective option for the disinfection of wastewater