APPLICABILITY OF SAND FILTERS FOR HOUSEHOLD WATER PURIFICATION

ABSTRACT

Small-scale water treatment processes seem to be the most suitable methods to provide relatively clean water for those who draw their water supplies from unprotected streams, wells and ponds. In this research, a household sand filter that can be made from locally available materials, and that can be operated and maintained by the householder has been designed. The unit was designed to work under declining rate taking into account economic factors and the intermittent trend of collecting water in rural areas. The filter unit has a capacity sufficient to treat the quantity of water required for a typical household of 7 persons at 15 lpcd. The cost of materials and labour required for a single tank is Birr 215.00 but mass production will result in a considerable offset in the cost. The household sand filter produces an effluent that satisfies the WHO recommendations for turbidity, color, odor, taste, pH and TDS. The filter is also capable of removing most of the bacterial load, thus reducing the probability of contracting water-related diseases. The filter can accommodate raw water turbidity of 100 NTU for three weeks without losing its capacity and efficiency but for higher turbidities, simple pretreatment methods such as plain jar sedimentation, straining or coagulation with natural seeds have been recommended. At lesser raw water turbidity levels the filter can be run for several weeks or months. The household filter can be used in emergency water supplies, temporary lodgings, concentration camps and isolated households and/or localities where it is not feasible to provide relatively clean water for domestic use by other means.

Note: The report is available at the Central Technical Library of the ESTC.

(Report 1999)

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