Recovery of indium from aqueous solutions by the Gram-negative bacterium Shewanella algae

This is the first report of an environmentally friendly microbial method to recover soluble indium(III) from aqueous solutions. Microbial uptake of soluble indium(III) was successfully achieved at room temperature over a pH range of 2.4–3.9 using the Gram-negative bacterium Shewanella algae. The microbial uptake of indium by the resting cells of S. algae was very rapid: 0.1 mol/m3 (11.4 ppm) indium(III) ions were completely collected by bacterial cells within 10 min. The pH value and the concentration of bacterial cells in the aqueous indium(III) solutions significantly affected the recovery fraction of soluble indium(III). After drying the indium-adsorbed bacterium at 50 °C for 12 h, the indium concentration in the dried biomass was approximately 5.4% (w/w), 474-times the concentration of indium(III) in the initial solution (0.94 mol/m3). Heating the bacterial cells at approximately 800 °C for 2 h yielded a solid condensate containing 40% indium (w/w), 4300-times the concentration of indium(III) in the initial solution. These methods represent an efficient and cost-effective method for recovery of indium(III) from wastewaters.

► The bacterium Shewanella algae was able to absorb indium(III) from aqueous solutions.
► The pH of the solution and the bacterial concentration affected the recovery fraction.
► Indium concentrates were prepared by drying or burning the microbial biomass.
► These methods represent an economical and efficient bioprocess for recovery of indium.