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/m(3) (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 inclium(III) solutions significantly affected the recovery fraction of soluble indium(III). After drying the indium-adsorbed bacterium at 50 C for 12h. 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/m(3)). 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 inclium(III) in the initial solution. These methods represent an efficient and cost-effective method for recovery of inclium(III) from wastewaters. (C) 2011 Elsevier B.V. All rights reserved.