Removal of Cadmium, Iron and Sulfate from Synthetic Acid Rock Drainage Using Metal-Tolerant Sulfate Reducing Bacterial Sludge

In the present study, sulfate reducing bacteria (SRB) granular sludge was made to remove cadmium, iron and sulfate from synthetic acid rock drainage (ARD) using upflow anaerobic bioreactor in the laboratory scale. The robustness of the process was tested by increasing stepwise metal and sulfate concentrations and decreasing influent pH. The result showed the bioreactor effectively treated synthetic ARD with high concentrations of cadmium, iron and sulfate. Sulfide precipitation was found to be the main mechanism of iron and cadmium removal. The dominate sulfate reducer in the bioreactor was Desulfovibrio which resulted in effective sulfate reduction and metals removal. The result suggested the SRB granular sludge could have a good potential for ARD treatment with high concentration of metals and low pH.