Effect of Radiation Intensity, Water Temperature and Support-Base Materials on the Inactivation Efficiency of Solar Water Disinfection (SODIS)

Abstract

Solar water disinfection (SODIS) harnesses energy from the sun to kill pathogenic microorganism in drinking water, thus making it safe for consumption. The effects of local conditions and materials on the efficiency of SODIS were investigated in this study for a period of five months. Waste polyethylene terephthalate (PET) bottles with varying optical properties were used as SODIS reactors. Water samples from deep well, shallow well, rainfall and spring were used for the study. SODIS reactors were exposed to sunlight for a period of 8 h under varying conditions of temperature and solar radiation. The study revealed that solar radiation intensity of 500–650 W/m2 and water temperature of 45–55 °C, were effective in destroying pathogens. Analysis of variance (ANOVA) confirmed statistically significant difference (p < 0.000) in water temperature of the reactors and support base materials used. However, this did not translate to significant difference in microbial population after 8 h of exposure to sunlight. Over 3 Log reduction in faecal coliform was recorded at a temperature of 55.5 °C within 3 h of exposure. At temperatures below 45 °C, 3 log inactivation of bacteria was not attained even after 8 h of exposure to sunlight. Hence, SODIS can be employed to address the immediate water quality needs of the most disadvantaged communities of Nigeria.