Effect of Fe(III) on the biotreatment of bioleaching solutions using sulfate-reducing bacteria

The selective precipitation of metals using H2S produced biologically by sulfate-reducing bacteria (SRB) was put forward to dispose bioleaching solutions. Fe(III) is a common ion in the bioleaching solutions, and Fe(III) could inhibit the growth of SRB. The purpose of this paper is to investigate the influence of Fe(III) on the growth/activity of a mixed culture of SRB. Batch tests were carried out in flasks with Fe(III) concentrations at 0.2, 1, 5 and 10 g/L respectively. To avoid the impact of precipitation, addition of sodium citrate to the medium was also studied. Sulfate removal rates were greater than those in samples without iron, except in the system with a high iron concentration of 10 g/L. It is found that the mixed culture of SRB can tolerate high concentrations of Fe(III) up to 10 g/L. After adding sodium citrate, SRB can tolerate higher concentrations of Fe(III), and the sulfate removal rate was the highest in the system with 5 g/L Fe(III).