Electrochemical remediation of acid mine drainage

Acid mine drainage (AMD), which has long been a significant environmental problem, results from the microbial oxidation of iron pyrite in the presence of water and air, affording an acidic solution that contains toxic metal ions. Electrochemical treatment of AMD offers possible advantages in terms of operating costs and the opportunity to recover metals, along with cathodic reduction of protons to elemental hydrogen. This work describes the electrolysis of synthetic AMD solutions containing iron, copper and nickel and mixtures of these metals using a flow-through cell divided with an ion exchange membrane. Iron was successfully removed from a synthetic AMD solution composed of FeSO4/H2SO4 via Fe(OH)(3) precipitation outside the electrochemical cell by sparging the electrolysed catholyte with air. The work was extended to acidic solutions of Fe2+, Cu2+, and Ni2+, both singly and in combination, and to an authentic AMD sample containing principally iron and nickel.