Evaluation of Chlorine Gas and Sodium Hypochlorite Injection Disinfection Methods Utilized by the Misamis Occidental Water District

Chlorination has been used by the Misamis Occidental Water District (MOWD) in Ozamiz City as a method of water disinfection to ensure public health safety. This study was conducted to evaluate the chlorination systems (gas chlorination and sodium hypochlorite injection) of MOWD. Specifically, this study determined the relationship between chlorine residual in water and the distance of flow. The study also determined if chlorine residual in the water system passed the minimum standard set by the Philippine National Standards for Drinking Water and the Local Water Utilities Administration. This study further evaluated which of the two chlorination systems is economical, more effective disinfectant, and at the same time safer to use. This is a correlational- survey type of research. Using the SMART LaMotte Colorimeter, chlorine residual determination was conducted at several locations in the water system served by the Bacolod and Carangan pumping stations. A site investigation was conducted and the operation of chlorination facilities was assessed. Results showed that chlorine gas and sodium hypochlorite are equally effective as disinfectant. Gas chlorination is more cost-effective than sodium hypochlorite injection but it requires regulations for safe handling, storage and operation. Free chlorine is decreasing as it traveled farther from the injection point of chlorine, thus, there were some locations in the water system in which the free chlorine was below the minimum standard of 0.20 ppm. Although the free chlorine was below the standard but the water system was free of pathogens based on the information from MOWD.