Effect of contaminated filtration sand on performance of household biosand filters

Household biosand filters are one point-of-use water treatment technology that can be used to provide clean drinking water to people living in communities without access to improved water supplies. There have been several studies investigating the importance of design variables on biosand filter performance, and biosand filters have been demonstrated to improve health outcomes in communities were they have been deployed. In constructing the biosand filter, it is recommended that sand from a rock quarry or gravel pit be used as filtration sand, as it is likely to be uncontaminated by waterborne pathogens. However, due to the cost or availability of sand from these sources, river sand may be used for filtration sand in a biosand filter. If the river water is contaminated with pathogens, it is likely that the sand will also be contaminated. In this study, we investigated the use of contaminated river sand on removal efficiencies of E. Coli and total coliforms from a biosand filter in the laboratory and installed in a community in Madagascar. We found that in the laboratory, the biosand filter constructed with contaminated sand had lower removal efficiencies than a filter constructed with clean sand over a 26 day period. In the field, we found that a biosand filter loaded with filtration sand obtained from a contaminated river performed well with removal efficiencies greater than 95%.