Assefa, Berhanu (PhD)Tefera, Nurelegne (PhD)Hassen, Ahmedin2018-07-112023-11-102018-07-112023-11-102007-01http://etd.aau.edu.et/handle/12345678/8064People in several regions of the Rift Valley of Ethiopia are suffering from skeletal and non-skeletal fluorosis as result of consuming water containing excessive fluoride. Defluoridation of drinking water using variety of material has been suggested by different researchers. This study assesses the fluoride adsorption characteristics of clays collected from different areas in Ethiopia. Bombawoha clay, Combolcha clay and Muger clay 2 were found to have the better potential as fluoride adsorbents. The effect of contact time, amount of adsorbent dose, pH, particle size, heat treatment of adsorbent and initial concentration of fluoride was investigated. The adsorption was rapid during the first one hour. The adsorption efficiency of fluoride was increased with adsorbent dosage. The defluoridation capacity was appreciable with in acidic pH range. Clay adsorbents treated in the range between 400 to 600oC gave better fluoride removal. The fluoride adsorption efficiency depends directly with initial fluoride concentration. The adsorption data were well fitted to the Langmuir isotherm model with adsorption capacity of 0.136, 0.168, and 0.191 for Bombawoha clay, Combolcha clay and Muger clay 2 respectively. Laboratory scale column were conducted and showed good removal of fluoride. At breakthrough the three clay samples Bombawoha clay, Combolcha clay and Muger clay 2 showed 0.1248, 0.235, 0.239 mg/g of adsorption capacity, 1.64, 1.1, 1.02 mg/L of residual fluoride and 300, 500, 500 mL of breakthrough volume respectively.enProcess Engineering StreamThesis