Ferrous Iron Oxidation in Packed-Bed Reactors at Elevated Temperatures

Abstract

The ferrous iron oxidation by mixed culture of moderately thermophilic microorganisms (Sulfobacillus thermosulfidooxidansSh 10-1 andAcidiplasmaMBA-1) was investigated in continuous experiments in three packed-bed reactors connected in series at temperature 55°C, and a pH of 1.0. Two solutions were used in the experiments. The first one contained (g L-1) 59 Fe2+, the second one contained (g L-1) 59 Fe2+, 16 Fe3+, 2 Cu2+, 2 Zn2+. The hydraulic retention time was 120 hours. Iron oxidation rates in the experiment with the first solution were 0.5, 0.35, and 0.2 g L-1h-1in first, second and third reactor, respectively. The oxidation rates in the experiment with the second solution were 0.3, 0.2, and 0.185 g L-1h-1in first, second and third reactor, respectively. Iron oxidation efficiencies in the experiments with the first and second solutions were 77% and 47%. Stable continuous iron oxidation at high temperature was successfully demonstrated, but further investigations are required for improving the rate and efficiencies of oxidation.