Fungal leaching of metals from electronic scrap

The present study was carried out to develop an economically feasible and environmentally friendly technique to extract metals such as Al, Fe, Cu, Zn and Ni from electronic scrap by employing Penicillium chrysogenum strain KBS3. Studies were carried out in various leaching modes, including one-step leaching with combined growth and leaching phases, two-step leaching with alternative growth and leaching phases, spent medium leaching with separated growth and leaching phases, leaching with fresh growth medium without fungal culture, leaching with deionized water, and leaching with commercial organic acids. The main lixiviants produced in leaching Mode 1 were citric, tartaric, oxalic and gluconic acids in notable concentrations, showcasing various efficiencies across leaching methods. At 5% pulp density, both leaching Modes 1 and 2 showed similar metal extraction yields from the electronic scrap at 35º C. Approximately 96% Al, 98% Zn, 48% Cu, 25% Fe, 66% Pb and 73% Ni were extracted in leaching Mode 1 in 14 days. In comparison, leaching Mode 3 exhibited even higher Cu extraction, emphasizing the significance of the chosen leaching method. This research indicates that fungal leaching is a viable alternative for recovering valuable metals from electronic waste.