Effectiveness of Solar Disinfection for Household Water Treatment

Abstract

Scarcity of water is one of the most important problems worldwide. The lack of freshwater and its dissimilar distribution together with inadequate sanitation and hygiene in low-income areas makes that nowadays millions of people are drinking contaminated water with fecal contamination. As a result, a number of waterborne pathogens present in this water induce serious diseases that, in many cases could be lethal in the most vulnerable population. Solar disinfection (SODIS) is an environmentally sustainable, low cost and simple point-of-use (POU) household water treatment method which can eliminate the pathogen responsible for contaminating water in any remote areas without any careful guidance and recent studies show that they may implemented as an effective method of disinfection of microbiologically contaminated water. In this study, an intensive assessment of effectiveness of solar disinfection under different seasonal variation in Bangladesh along with using different materials and modification are elaborated following the guidelines of WHO household water treatment methods. Escherichia coli (E. coli) spiked into sample water are put in different containers like polyethylene terephthalate (PET) bottles and plastic bag are exposed to solar irradiance by laying on corrugated steel sheet and aluminum foil paper. In summer season, a 5.4 log reduction using PET bottles are observed on corrugated steel sheet from 8hr exposure and regrowth of bacteria occurs after 12hr but in monsoon season since the weather is cloudy, a 4.22 log reduction using plastic bag for 16hr exposure are observed on aluminum foil paper laid on corrugated steel sheet. In Page | 11 winter season, a 4.72 log reduction observed using plastic bag for 8hr exposure on same conditions and the regrowth prevails in all season. The physicochemical parameters of samples assessed did not show any variation with respect to the seasonal variation. Using plastic bag with foil paper laid on corrugated sheet is more effective in the inactivation of bacteria for all seasons. Furthermore, this study illustrates modelling of required time for 4-log inactivation of bacteria by using Weibull distribution model. In summer season, only 3 hours of SODIS could give highly protective water according to WHO guideline of HWT technologies and further in winter and monsoon season it takes less time of treatment by solar irradiance. However, the model also shows the acquired data from required experiments done fits well and the minimum and maximum irradiance of different seasons are shown and recommended the feasible way of solar disinfection.