Browsing by Author "Shewangizaw, Derib"

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    Investigation of Media for Removing Fluoride from the Ethiopian Rift Valley Ground Water
    (Addis Ababa Universty, 1998-06) Shewangizaw, Derib; Moges, Ghirma (PhD)
    The chemical properties of fluorine, fluoride in the human environment; the fluoride absorption, distribution, and excretion in the human system are briefly reviewed. The beneficial and toxic effects of fluoride to human, plants, and animals; and several defluoridation methods have also been briefly reviewed. Aluminium oxide, alumina, was prepared from aluminium sulphate (hydrate), produced locally in Awash Melkasa. The defluoridation capacity of 2% HCI treated laboratory product alumina was compared with commercial acidic alumina. The amounts of acidic alumina required to bring the fluoride concentration to less than the recommended value by WHO (1.5 mgIL F) were determined for different concentrations of fluoride. Studies were also made for local kaolin (beneficiated kaolin), commercial kaolin, and diatomaceous earth. Local kaolin was found to be a promising defluoridating material. The parameters investigated were contact time, mass, and volume effect. To some extent the pH effect was also considered. The overall result shows that acidic alumina and local kaolin are very efficient defluoridating material.