Life cycle assessment of bioleaching for metal recovery from waste PCBs: A sustainable approach using openLCA

The rapid expansion of electronic waste (e-waste) has intensified the need for sustainable metal recovery methods which can replace energy-intensive pyrometallurgical and hydrometallurgical routes. This study presents a cradle-to-gate Life Cycle Assessment (LCA) of a bioleaching-based Printed Circuit Board (PCB) recycling system using experiment-derived inventory data for realistic environmental attribution. The process integrates mechanical pre-treatment, bioleaching by Exiguobacterium himgiriensis and Enterobacter quasihormaechei , selective precipitation, solvent extraction, and final metal refining, modelled in openLCA 2.4.1 with Ecoinvent 3.11 database. For the treatment of 1 kg of waste PCB the bioleaching-based recovery process resulted in a global warming potential of 0.03511 kg CO 2 -eq, freshwater ecotoxicity impact of 0.02804 CTUe, and marine eutrophication potential of 8.96 × 10 − 5 kg N-eq. Contribution analysis and Monte Carlo uncertainty propagation (5000 iterations, 95% confidence intervals) indicated that energy consumption, downstream metal recovery, and trace metal emissions were the main factors influencing environmental performance. Process hotspot rankings remained invariant across all uncertainty scenarios, validating the robustness of optimization strategies. Metal recovery efficiencies of Cu, Fe, Zn, and Ag were 90%, 82%, 58%, and 92%, respectively. Sensitivity analysis showed that renewable electricity substitution and effluent metal recovery could cut impacts by over 60%. The findings highlight bioleaching as a scalable, environmentally superior route for PCB metal recovery within circular economy frameworks.