Solar Disinfection of Water Using Transparent Plastic Bags

T.A. Lawand, J. Ayoub, H. Gichenje


A series of tests exposing contaminated river water in transparent polyethylene bags to solar radiation has indicated that there is a distinct disinfection effect. Generally, for bags of shallow water depths of less than 10 cm, pathogenic bacteria are inactivated after exposures varying from 4 to 6 hours under bright solar radiation conditions. There appears to be a synergetic effect of solar radiation and heat when water temperatures rise above 40 . Faecal coliforms are the indicator organisms in this experiment. Tests show total bacterial inactivation when water samples are exposed to direct sunlight for at least 5 hours. Faecal coliforms enumeration was carried out by the Membrane-filtration method using prepared 2 ml ampoules of nutrient agar as the growth medium and at an incubating temperature rang of 44.3 to 44.7 for 24 hours.

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