Review: Biorecovery of precious metals from waste printed circuit boards

Presently, as electronic waste continues to surge, waste printed circuit boards (WPCBs) have emerged as one of the fastest-growing waste category. This causes severe environmental pollution and threats to human health. However, there are many precious metals in WPCBs. To achieve environmental conservation and sustainable development , adopting biorecovery techniques for the extraction/reuse of WPCBs has become a promising approach. Firstly, this review provided an overview of e-waste material categorization, pretreatment methods, and screening methods. Secondly, biorecovery was decomposed into two primary domains: bioleaching and biosorption , with detailed reviews conducted on the mechanisms and leaching yields of these two processes. Thirdly, a review of purification techniques for bioleaching solutions was conducted. Finally, a comprehensive comparison was conducted on the similarities and differences between bioleaching and biosorption. The maximum bioleaching leaching yields for Au, Ag, and Pt were approximately 76.6%, 90%, and 60%, respectively, while the maximum biosorption leaching yields for Au was approximately 100%. This review aims to establish a foundation for the application of biorecovery at an industrial scale.