Bioleaching of Cu and Pb from printed circuit boards by Rhizopus oligosporus and Aspergillus niger

The purposes of this study was to evaluate the ability of Aspergillus niger and Rhizopus oligosporus for one-step bioleaching of Cu and Pb in printed circuit boards (PCBs) scrap from e-waste recycling shops, compared to acidic extraction with citric and lactic acids. The fungal spore suspension was cultivated in potato dextrose broth with dried PCBs and a shaker for 42 days. Every 7 days the leachates were analyzed for Cu and Pb concentrations using atomic absorption spectroscopy. The Cu and Pb concentrations in PCBs in e-waste recycling shops were 152.81 ± 26.54 and 25.62 ± 8.33 g kg–1 PCBs, respectively. The leaching experiment showed that 0.05 M citric acid was the most efficient leaching pure acid: more than 54.59% of Cu and 79.55% of Pb was released into solution. Heavy metal leaching by the lactic acid was less efficient. The best metal bioleaching efficiency was achieved by A. niger fungus, which extracted approximately 46.92% of Cu, and almost 30.63% of Pb from PCBs. R. oligosporus leached only 8.53 and 19.61% of Cu and Pb, respectively.