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Solar Disinfection

SODIS - indonesia sodis eawag

SODIS water disinfection in Indonesia. (Photo: SODIS Eawag)

Solar disinfection (SODIS) uses solar energy in the form of ultraviolet radiation and infrared heat to disinfect contaminated drinking water.

Poor water quality poses a major threat to human health in developing countries and water-borne illnesses are often a leading cause of childhood mortality. According to a 2004 World Health Organization (WHO) study, diarrheal diseases alone are responsible for the deaths of 1.8 million people every year, with 88% of the cases attributed to unsafe water supply, sanitation and hygiene (see reference 1). Improvements in water supply, sanitation facilities, and hygiene practices can result in a 65% reduction in deaths from diarrhea. Solar disinfection can be used for the treatment of household water is used in different parts of the world.

Water to be treated for drinking is placed horizontally in transparent glass or plastic containers and exposed to full sunlight for about six hours.

Field investigations of the effectiveness of SODIS have been carried out on three continents. Bacteria are consistently destroyed upon exposure to sunlight for an adequate amount of time, but the duration of exposure required depends on the intensity of sunlight (which in turn depends on altitude, latitude, season, time of day, and cloud and/or pollution cover), the type of bacteria, the characteristics of the container (color, size, shape, thickness, transparency to sunlight, and orientation to sun), and depth and clarity of the water.

SODIS is simple, inexpensive, and provides good quality water and does not lead to the destruction of trees or other natural resources. SODIS is not without its limitations, however. SODIS does not remove chemical contaminants in drinking water, if any exist, and it does not change the taste or the odor of source water. So if these qualities are unacceptable in the source water, exposure to sunlight will not improve them.


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