Effectiveness of in-line chlorination in a developing world gravity-flow water supply

Abstract

An in-line PVC chlorinator can be an appropriate water disinfection technology to inactivate pathogens and improve water quality in community-managed water supply systems. Free chlorine residual was measured at five locations after the insertion of one chlorine tablet into an in-line PVC chlorinator and, in a second experiment, after the insertion of three chlorine tablets. The Ct (concentration × time) method for disinfection was used to compare the measured free chlorine residual with the residual required to inactivate a recommended percentage of common pathogens found in gravity-flow water systems in the developing world. The two operating conditions, each with a contact time of 56.6 minutes, had a free chlorine residual required to disinfect all viruses and bacteria considered in this study but not above the 0.27 mg/L needed to inactivate the protozoa Giardia lamblia, a common pathogen in developing countries that causes diarrhoea. The research suggests that an in-line PVC chlorinator can be a simple, effective technology that utilizes local materials to provide safe drinking water for rural communities; however, water committees need to iteratively test free chlorine residual in the system until sufficient residual is reached.