Factors affecting bioleaching of metal contaminated sediment with sulfur-oxidizing bacteria

Bioleaching is one of the feasible methods for the treatment of sediments contaminated with heavy metals. Effects of solid content, substrate (sulfur) concentration and pH on the performance of bioleaching process were investigated in this study. It was found that rates of sediment acidification and metal solubilization decreased with increasing solid content. Besides, sulfur concentration greater than 5 g/l was found to be inhibitory to bacterial activity and metal solubilization from sediment. It was concluded that a substrate concentration of 5 g/l in reactor was the optimum concentration for bioleaching process. It was also observed that solubilization of heavy metal from the sediment was highly pH-dependent. For all values of solid content and sulfur concentration tested, the efficiency of metal solubilization from sediment followed the order Cu>Zn>Pb>Cr.