Effectiveness of Solar Disinfection (SODIS) in Removing Pathogenic Microorganisms

Abstract

Water is the most important natural resource in the world and availability of safe drinking water is a high priority issue for human existence and quality of life. Unfortunately water resources are coming under increasing pressure due to population growth, over-use and wastage. The World Health Organization (WHO) estimates that 884 million lack access to improved water supplies. Many more are forced to rely on sources that are microbiologically unsafe, resulting in a higher risk of waterborne disease transmission including typhoid, hepatitis and cholera. As ever, the poor are the worst affected from waterborne disease. In n developing countries, 50% of the population are exposed to polluted water sources and these peoples are the main contributors to an estimated 4 billion case of diarrhea each year. These factors result in an estimated 2.2 million deaths each year, the majority of which are children under the age of five. Solar disinfection (SODIS) of drinking water is one of the WHO approved point-of-use household water treatment technologies for drinking water (WHO/UNICEF 2011). It requires that water in transparent containers (usually poly-ethylene terephalate (PET) bottles) be exposed to direct sunlight for minimum period of 6 hours under clear sky conditions in which waterborne pathogens are inactivated thus making the water safe to drink. Pathogenic inactivation is due to the synergistic effect of ultraviolet (UV) light and heat produced by solar radiation. SODIS is very cost effective and user friendly water treatment technology comparing to the existing systems. To reduce childhood mortality, SODIS would be a realistic and cheap opinion for provision of safe drinking water in Bangladesh since ample sunlight is available throughout the year.