Chebude YonasFidel KessyJackson Magori2021-09-162023-11-182021-09-162023-11-182021-06-26http://etd.aau.edu.et/handle/12345678/27918The coexisting fluoride and arsenic in the groundwater sources of drinking water has been threat to thegeneral public health worldwide and in particular to the East African Rift Valley (EARV). The use of bone char and Nalgonda technique for defluoridation face rejection by the users in the area due to culturalbeliefs and foul smell they produce. New, cost-effective method for removal of fluoride and/ or arsenic istherefore required. In this study the electrocoagulation process using hybrid aluminum-iron electrode wasoptimized and evaluated for the removal of arsenic and fluoride from water. At the optimized operationparameter of 9.90 mAcm-2, pH 7.5; the hybrid Al-Fe EC reduced 16 mg/L fluoride and 200 μg/L arsenicto 1.12 mg/L and 9.60 μg/L, respectively in 50 minutes with an operation cost estimated to 0.99 $/m3.Moreover, the study investigated the effects of co-existing ions in water on the performance of Al-Fe ECand found that Ca2+ (0.5-100 mg/L) enhanced F- removal, while SO42- (> 80 mg/L) and NO3- (> 75 mg/L)suppressed F- removal. On the other hand, NO3- (0.5-100 mg/L), SO42- (> 50 mg/L), Mg2+ (> 50 mg/L),and Ca2+ (> 50 mg/L) reduced As3+ removal. The combination of Mg2+ (˂ 70 mg/L) and Ca2+ appears toincrease the fluoride removal, while the combination of other ions had antagonistic effects on the removalof both F- and As3+. Carbonates showed an insignificant influence on the removal of both pollutants. Theeffect of co-existing ions on the performance of hybrid Al-Fe EC was found to depend on the type andconcentration of individual co-ion. The last objective reports on the adsorption isotherm and kinetic ofarsenic and/or fluoride. Adsorption of fluoride and arsenic followed both Freundlich and Langmuirmodels. The adsorption processes for fluoride and arsenic were spontaneous and physical in nature withmonolayer maximum adsorption capacities of 76.36 mg/g and 1.14 mg/g, respectively in single systems.In a binary mixture adsorption capacity of arsenic was 0.40 mg/g while that of fluoride was 75.60 mg/g.Moreover, the kinetic of fluoride and or arsenic removal followed pseudo second order model. Theremoval of fluoride and arsenic were through ionic exchange and electrostatic attraction, respectively.Meanwhile, a real groundwater (F- = 22 mg/L) and simulated groundwater (As3+ = 0.22 mg/L and F- = 7.6mg/L), have also been treated successfully. The optimized Al-Fe EC upon scale up can be used for theremediation of fluoride and/or arsenic from contaminated groundwater in EARV.enSimultaneous Removal Fluoride Arsenic In Drinking Water Electrocoagulation Technology Using Hybrid Al-Fe ElectrodesThesis