Treatment of Mine Water by a Microbial Mat: Bench-scale Experiments

Abstract.   We investigated the treatment of acid mine drainage (AMD) by a blue-green algae-microbial consortium and substrate (containing powdered goat manure, wood chips, and soil) in 1 m³ bench scale biological treatment test cells. The microbial mat resulted from the interaction of bacteria and filamentous blue-green algae (predominantly Oscillatoria spp). The experiments were carried out for different water column heights, and were evaluated for 24, 48, 72, 96, and 168 hours of retention. Within 24 hours of retention, the pH increased from 2.93 to 6.78 as net alkalinity went from -125 mg/L to 197 mg/L as CaCO₃. Turbidity decreased by 33–54%, sulphate decreased by 23–29%, and hardness decreased by 19 to 26%. We also observed that: 95% of the Fe, 79–97% of the Cu, 84–86% of the Zn, 88% of the Pb, 59–83% of the Co, 22–62% of the Ni, and 28–45% of the Mn were removed. A blue-green algae/microbial mat consortium may be a cost–effective treatment technique for removing metals from AMD.