Sustainable Optimization of Biotechnology for Cu Recovery from Printed Circuit Boards

The increase of waste from electrical and electronic equipment (WEEE), rich in valuable elements, has pushed research toward the development of sustainability treatments for its exploitation. The high Cu concentration within printed circuit boards (PCBs) (around 20-25% w/w) makes them a promising secondary resource. The aim of this work is the optimization of the patented bioleaching process driven by the minimization of the environmental load in the global warming category. The first environmental assessment was carried out considering bioleaching in a stirred tank reactor, also including metal recovery operations, using the best conditions identified in previous works. A mathematical model for bioleaching prediction was integrated inside the LCA methodology and used in Monte Carlo simulations: this assessment highlighted the energy demand as the main criticality. Consequently, a fixed bed column leaching was investigated both experimentally and theoretically through a predictive model, starting with the chemical leaching with Fe3+ and recirculation, as preparatory to our Copper BIOTECH patented technology. The excellent agreement among the predictive model and the experimental data provided a powerful tool for optimization purposes. The mathematical model was applied to patented technology, and simulations allowed us to identify the best operative conditions in bioleaching. The innovative design allows for a decrease of around 70% of energy demand and around 55% of the impact in the global warming category. Our study is fundamental to boost the application of sustainable bioleaching technologies in the world. Moreover, our methodological approach represents a guideline to meet sustainability goals within circular economy approaches for strategic metals.