Biohydrometallurgical Recovery of Critical Metals from E-Waste: Recent Advances, Technology Readiness, and Future Perspectives

The rapid increase in the production and consumption of electronic and electrical equipment has resulted in a significant global increase in electronic waste (e-waste). This complex waste stream has valuable rare earth elements, precious metals, and base metals, positioning it as an important secondary resource for the recovery of critical metals. With proper extraction and recovery technologies, e-waste presents a strategic opportunity to supplement primary mineral resources and support supply chain security. However, as demand for critical metals continues to rise, conventional extraction methods often face limitations related to environmental impact, energy intensity, and chemical consumption. This review examines innovative and sustainable extraction techniques for recovering critical metals from e-waste, with particular emphasis on advancements in biohydrometallurgy. It explores the integration of biological processes, including the use of microorganisms and bioleaching, to enhance metal recovery while reducing ecological footprints. In addition, this review considers the role of advanced hydrometallurgical processing in improving efficiency and selectivity. Although substantial research has proved the technical feasibility of biomining for base metals, precious metals, and rare earth elements at laboratory scale, key challenges remain. Therefore, this paper moves beyond the question of whether metals can be bioprocessed and instead critically evaluates issues related to scalability, process integration, techno-economic viability, and sustainability.