Challenges in scale-up of bio‑hydrometallurgical treatment of electronic waste: from laboratory-based research to practical industrial applications

E-waste is rapidly growing in volume as a result of increasing consumption and reduced life expectancy of electronic products. Energy-intensive and cost-inefficient methods like pyrometallurgy and hydrometallurgy following chemical and/or physical separation steps are generally implemented for metal recovery from e-waste. As an environmentally sounder option, biohydrometallurgy was developed using microorganisms and their metabolic products to solubilize and recover metals from insoluble matrices like e-waste. Bioleaching applications to e-waste are still at the early stages of development and a techno-economic analysis indicates it is not yet viable. This review assesses peer-reviewed data gathered to establish the Technology Readiness Level of biohydrometallurgy for material recovery from e-waste at a pilot scale allowing the conclusion that bioleaching at the commercial scale currently faces diverse operational challenges that hamper its scale-up and industrial implementation.