Microbes, Metal(Loid)s and Microbe–Metal(Loid) Interactions in the Context of Mining Industry

Mining activities generate large quantities of wastes which pose threat to aquatic life, environment and human health, if left untreated. The generation of large quantities of wastewater with low concentrations of metals (for example: 10 mg/L Te(IV) in used solar cell leachate; 5–30 mg/L Cr, 0.14–21 mg/L Cu, 0.2–30 mg/L Ni, and 0.2–28 mg/L Zn in electroplating wastewater) makes the biological treatment processes more attractive, over physicochemical processes. Often, these wastes are laden with critical, scarce metals and are considered as resource due to their limited availability, cost and intended applications. Metal–microbe interactions through various redox reactions and acid-producing metabolism allow the extraction of base metals from ores. In the industrial biomining and bioleaching processes, microbes are employed for metal extraction from ores and the same can be applied for extraction of precious metals from low-grade ores, solid wastes and mine tailings. This book chapter presents an overview of metal–microbe interactions for potential biotechnological applications in the treatment of metal laden wastes generated in mining activities. These metal-microbe interactions include mobilisation (biomining) and immobilisation (biosorption, bioaccumulation, bioreduction and bioprecipitation) of metal ions present in different forms of wastes. Up to date studies on different microorganisms and biofilm systems employed for successful treatment and recovery of metals from wastes have been included along with underlying biochemical process. The chapter ends with a discussion on sustainable technological platforms such as bioelectrochemical systems, wherein the oxidation of organic contaminants in wastewater is coupled to the removal and recovery of metal ions from metal-bearing wastewater. Important studies on bioelectrochemical systems for the recovery of metal ions and associated removal mechanisms are provided.