Browsing by Author "Mbwette, T. S. A"

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    Horizontal flow roughing filters for rural water treatment in Tanzania
    (University of Dar es Salaam, 1983) Mbwette, T. S. A
    The failure of introduction of Slow Sand Filters (SSF) in drinking water treatment in Tanzania was attributed to the practice of designing them to filter raw waters containing high suspended solids loads directly. The subsequent operational difficulties usually resulted in abandoning them. The assessment of suitability of application of Horizontal Flow Roughing Filters (HRF) as an appropriate pretreatment prior to SSF has been done after investigation of the working conditions of a number of SSF at present, execution of field tests and making economic comparisons with chemically assisted sedimentation. Results proved that HRF can bring about considerable improvements of physical and bacteriological quality of water. Although its investment costs are a bit higher than for chemically assisted sedimentation, its annual operational and discounted costs are much less than the latter. HRF are technically and economically suitable for application in rural water supply schemes of Tanzania since they involve the use of only locally available skills and materials. Besides applying them as pretreatment prior to SSF, they can be used as sole treatment units of raw water in conjunction with plain sedimentation or on their own depending on the nature of the raw water sources. Further research is proposed to be done for the sake of increasing the knowledge of treatment processes involved in HRF.