Bioelectrochemical treatment of acid mine drainage dominated with iron

Treatment of acid mine drainage (AMD) dominated with iron (Fe), the most common metal, is a longterm expensive commitment, the goal of which is to increase the pH and remove Fe. In the present study, a proton exchange membrane microbial fuel cell (MFC) showed promise for the efficient treatment of an AMD dominated with ferric iron (pH 2.4 +/- 0.1; 500 mg L-1 Fe3+). Briefly, Fe3+ was reduced to Fe2+ at the cathode of the MFC, followed by Fe2+ re-oxidation and precipitation as oxy(hydroxi)des. Oxygen reduction and cation transfer to the cathode of the MFC further caused a rise in pH. A linear relationship was observed between the charge transferred in the MFC and the performance of the system up to 880 C. Optimal conditions were found at a charge of 662 C, achieved within 7 d at an acetate concentration of 1.6 g L-1 in a membrane MFC. This caused the pH to rise to 7.9 and resulted in a Fe removal of 99%. Treated effluent met the pH discharge limits of 6.5-9. The maximum power generation achieved under these conditions averaged 8.6 +/- 2.3W m(-3), which could help reduce the costs of full-scale bioelectrochemical treatment of AMD dominated with Fe. (C) 2012 Elsevier B.V. All rights reserved.