Manganese removal and characterization of manganese oxides induced by biologically and chemically on the matured sand.

Manganese pollution particularly in the form of dissolved Mn²⁺ is an important problem in groundwater treatment. The main approaches for Mn²⁺ removal from groundwater are chemical catalytic oxidation and biological oxidation. Their relative attribution to Mn²⁺ removal and relationship has not been clarified at the matured stage. An influent of water containing 2.0 and 4.0 mg/L Mn²⁺ was filtered through columns filled with manganese sand that had either been inoculated with a manganese-adapted microbial community or had been pre-oxidized with potassium permanganate. Either treatment resulted in good manganese removal capacities that maintained a final concentration in the effluent below 0.05 mg Mn²⁺/L at two concentrations for a period of 130 d. Among the matured period, the direct contribution rate of biological manganese removal was less than 20%. During operation, biological induction and chemical induction were both responsible for the formation of hexagonal Birnessite-type manganese oxide, whose physical characteristics were characterized and determined. Biological oxidation and chemical catalytic oxidation in the maturation of filter media were interlinked through the formation of Birnessite-type manganese oxide. Manganese removal during maturation was mainly attributed to cyclic autocatalysis rather than biological factors. [ABSTRACT FROM AUTHOR]