College of Engineering and Technology

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Browsing College of Engineering and Technology by Author "Abdi, Khamis Chome"

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    Removal of excess fluoride from drinking water for household units in Tanzania with emphasis on regenerated filter media
    (University of Dar es salaam, 1990) Abdi, Khamis Chome
    Excess fluoride in drinking water is a problem in some parts of Tanzania, especially the northern regions and a few districts covering the southern highlands. Therefore fluorosis still remains a public health problem in these areas manifesting itself in the form of crippling fluorosis in extreme cases, like in Arusha Region. The prevention of fluorosis by developing simple and inexpensive methods of fluoride removal should be encouraged. The primary objective of this study is to investigate methods of fluoride removal incorporating the regeneration of the filter medium at the household level, with a view to recommending a suitable method. Several methods of fluoride removal were reviewed and the use of bone was selected for investigation. Bone was used both as bone char and granulated bone in the ICOH defluoridator, which is a household defluoridation device. 1250 grammes of bone char of 2.0 mm particle size with a flow rate of 15 litres per hour was used. For granulated bone, 1000 grammes of 0.5 mm particle size with a flow rate of 13.2 litres per hour was used. Two sources of water were used with 3.2 mg/1 and 22.0 mg/1 fluoride concentration. A mixture of calcium chloride and sodium dihydrogen sulphate solution was used for the regeneration of the filter medium. Both bone char and granulated bone gave good and encouraging results at all levels of regeneration. Maximum efficiencies of 96.9% and 99.5% were reached for bone char and granulated bone respectively. However the performance of both media decreased with the increase in the fluoride concentration of the raw water, the volume of water treated and the level of regeneration. In most cases granulated bone gave better fluoride removal results compared to bone char.Generally granulated bone is more preferable than bone char in fluoride removal at the household level.