Immobilization of Acidithiobacillus ferrooxidans on monolithic packing for biooxidation of ferrous iron

The oxidation of ferrous iron (Fe2+) in solution using Acidithiobacillus ferrooxidans has industrial applications exclusively in the regeneration of ferric iron (Fe3+) as an oxidizing agent for the removal of hydrogen sulfide from waste gases, desulfurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this investigation was to increase the bio-oxidation rate of ferrous sulfate by using immobilized cells. Rate of Fe2+ oxidation was determined in a packed-bed bioreactor configuration with monolithic particles being used as support material.Biooxidation of ferrous iron by immobilized cells was investigated in repeated batch culture and continuous operation using a laboratory scale packed-bed bioreactor. On this account, effects of process variables such as dilution rate and initial concentrations of Fe2+ on oxidation of ferrous sulfate were consequently investigated. During repeated batch culture, the immobilized-cells were stable and showed high constant iron-oxidizing activities. A maximum Fe2+ oxidation rate of 6.7 g/l/h was achieved at the dilution rate of 2 h-1, while no obvious precipitate was detected in the bioreactor.