Bioleaching of heavy metals from metal tailings utilizing bacteria and fungi: Mechanisms, strengthen measures, and development prospect

Recovering key metals from secondary sources is an indispensable strategy for preventing metal shortages and reducing the risk of toxic releases into the environment. Metal mineral resources continue to be depleted and the global supply chain will face metal scarcity. The use of microorganisms for metal transformation plays an important role in the bioremediation of secondary resources. It shows great potential for development due to its compatibility with the environment and possible cost effectiveness. The results of the study show that the influence of bioleaching processes and effects are mainly analyzed from microorganisms, mineral properties and leaching environmental conditions. In this review article, we elucidate light on the role and mechanisms of fungi and bacteria involved in extracting different metals from tailings, including acidolysis, complexolysis, redoxolysis, and bioaccumulation. Key process parameters that affect the efficiency based bioleaching are discussed, providing referenceable pathways to improve leaching efficiency. The investigation concludes that exploitation of the functional genetic role of microorganisms and their optimal growth conditions can achieve efficient leaching of metals. It was found that the improvement of microbial performance was achieved at the level of mutagenesis breeding, mixed culture microorganisms, and genetics. Moreover, control of leaching system parameters and removal of passivation films can be achieved by adding biochar and surfactants in the leaching system as an effective means to improve tailings leaching. Knowledge about cells with minerals and their detailed interactions at the molecular level is still relatively scarce and the field could be deepened and this area needs to be further explored in the future. The challenges and the key issues associated with the bioleaching technology development are elaborated as a green and effective bioremediation strategy for the environment and prospects for imminent are also highlighted.