Manganese amended activated alumina for adsorption/oxidation of arsenic

In a laboratory study, manganese amended activated alumina (MAA), prepared by calcining (400 degrees C) manganese. acetate-impregnated activated alumina, showed promise as a more. effective medium than activated alumina (AA) for use in small municipal drinking water systems or point-of-use treatment, for removing arsenic [As(III) and As(V)] from groundwater. Batch adsorption/oxidation kinetic tests indicated that in fixed-bed operation, with a bed flowthrough time of 10-20 min, MAA would be a more effective medium than AA in removing arsenic [As(V), As(III), and As(III) and As(V) (present together)] from groundwater. In three cycles of downflow column test [bed depth 200 mm; bed flowthrough time 20 min; influent arsenic 1.0-0.6 mg/L As(III) and 0.4 mg/L As(V)], breakthrough bed volumes at the World Health Organization guideline value of 0.01 mg/L for arsenic, in drinking water were 580, 550, and 485, and 825, 770, and 695, respectively, for AA and MAA. During regeneration (backwashing with a sodium hydroxide solution), 84-88% (for AA) and 86-89% (for MAA) of the removed arsenic was recovered. Manganese concentration in the MAA column effluent was low (below 0.02 mg/L). A detailed study addressing the effects-of some important factors (water pH, concentration and type of competing ions, and fouling by organics) on the process is needed.