Journal of Water, Sanitation and Hygiene for Development | 01.1 | 2011
Impact of a natural coagulant pretreatment for colour removal on solar water disinfection (SODIS)
Sarah A. Wilson and Susan A. Andrews
Solar water disinfection (SODIS) is the process of treating microbiologically contaminated water inclear plastic bottles through exposure to sunlight. One of the major limiting factors of this treatmentis source water quality. This work investigates the impact of source water colour on SODIS efficiencyand evaluates a natural coagulant for colour removal. The ability of Moringa oleifera seed emulsion toboth clarify and decolourize source waters was investigated as a coagulation pretreatment for SODIS.
This coagulant reduced the colour by more than two-thirds and achieved up to 1-log10 bacterialremoval (90%). The combined Moringa oleifera coagulation-SODIS treatment sequence was tested inhighly coloured natural source water and was found to reduce the sunlight exposure time requiredby up to 2 hours. However, despite being an effective clarification and decolouring process, thepretreatment may not shorten the overall treatment time because of its own labour and timerequirements, potentially decreasing the treatment compliance rates. In addition, while total coliformand heterotrophic bacteria regrowth was observed during overnight storage of the treated water, noEscherichia coli regrowth was found to occur.
