Bioleaching for environmental remediation of toxic metals and metalloids: A review on soils, sediments, and mine tailings

Owing to industrial evolution, a huge mass of toxic metals, including Co, Cu, Cr, Mn, Ni, Pb, and Zn, and metalloids, such as As and Sb, has inevitably been released into the natural environment and accumulated in soils or sediments. Along with modern industrialization, many mineral mines have been explored and exploited to provide materials for industries. Mining industries also generate a vast amount of waste, such as mine tailings, which contain a high concentration of toxic metals and metalloids. Due to the low economic status, a majority of mine tailings are simply disposed into the surrounding environments, without any treatment. The mobilization and migration of toxic metals and metalloids from soils, sediments, and mining wastes to water systems via natural weathering processes put both the ecological system and human health at high risk. Considering both economic and environmental aspects, bioleaching is a preferable option for removing the toxic metals and metalloids because of its low cost and environmental safety. This chapter reviews the recent approaches of bioleaching for removing toxic metals and metalloids from soils, sediments, and mining wastes. The comparison between bioleaching and chemical leaching of various waste sources is also discussed in terms of efficiency and environmental safety. Additionally, the advanced perspectives of bioleaching for environmental remediation with consideration of other influencing factors are reviewed for future studies and applications.