Feasibility of Solar Energy in Disinfection of Drinking Water in Iran

The solar disinfection of water (SODIS) is a simple technique used to destroy pathogenic microorganisms and so it can improve microbiological quality of drinking water. Many countries are in good positions with respect to receiving solar radiation and Iran ranks first in this regard. Thus, it is important for health authorities to prefer this simple method for use in rural areas of the Country and at abnormal conditions instead of other complicated techniques. The main objective of this study was to determine the efficiency of locally available bottles (not transparent to UVC and semi-transparent to UVA) for use in solar disinfection of water in non-urban areas of Iran. For this purpose normal plastic bottles were used and the solar disinfection efficiency was evaluated in terms of fecal coliform reduction of contaminated surface water samples. Two types of locally available normal plastic bottles with UV transmittance values of 0.1 and 0.8 percent were selected and used according to WHO guidelines about SODIS in the disinfection process of water samples from a surface water resource. Examinations of microbiological quality of all water samples have been performed by determination of fecal coliform group (5 tube fermentation technique) according to the procedure outlined in Standard Methods. Water sampling had been accomplished in the fall of 2006. Results indicate that SODIS is also possible even if available plastic bottles with less transparency are used instead of standard bottles. According to the results obtained by use of these bottles, about 99.9% disinfection of water (up to 3 log reduction in fecal coliforms) is possible at the temperature of 39.6 degree centigrade. Also, it should be noted that by substituting the bottle with less UVT with the more transparent one, it would be possible to decrease the required contact time for 3 log reduction of microbial indicator from 8 to about 6 hours. Results of this 10 study clearly indicate that utilizing of both locally available bottles used in this study may have enough justification for SODIS process in non-urban areas and communities of Iran which mostly have warm climates.