GEOCHEMISTRY AND BIOREMEDIATION OF MINING CONTAMINATED WATER IN THE BLACK WARRIOR COAL BASIN, NORTHERN ALABAMA

We investigated the hydrology and water chemistry of three acid mine drainage (AMD) discharges in Walker (Cane Creek) and Jefferson Counties (New Castle and Five-Mile Creek) of northern Alabama. Elemental and redox chemistry of water samples from the field indicated three different hydrochemical facies of AMD (i.e., iron, aluminous, and sulfate). The acidity and redox chemistry of AMD are primarily controlled by the oxidation of Fe(II) and hydrolysis of Fe(III) (at pH≈3) and Al (at pH≈4.5). Field and laboratory data indicate that mineral precipitates play a major role in (1)the control of Fe and Al solubility and AMD acidity, and (2)the absorption and retention of selected toxic elements (e.g., As) under acidic conditions. We performed laboratory column experiments to study the effects of sulfate-reducing bacteria (SRB) on bioremediation of AMD. The increase in pH and reductions in free-Fe and Al suggest that the successful remediation of contaminated water by SRB is possible.