Microbial Processing of Waste Shredded PCBs for Copper Extraction Cum Separation—Comparing the Efficacy of Bacterial and Fungal Leaching Kinetics and Yields

The recycling of electronic scrap is an important subject not only from an environmental
aspect but also for recovering metal resources such as copper. In this work, the microbial extraction
of copper and other metals (Cu, Ni, Co, Fe and Al) present in the depopulated and shredded printed
circuit board (PCB) is elaborated. Bacterial strains of A. ferrooxidans, A. thiooxidans and a fungal
strain, A. niger are used for copper extraction along with other metals from shredded PCBs. An
optimum metal recovery of 93% Cu was obtained at 308 K, pH 2 using 8% pulp density in 10 days
by a mixed culture of A. ferrooxidans and A. thiooxidans. Whereas using A. niger, a metal recovery of
66% Cu was reported using similar experimental conditions. The results show the higher potential
ability of bacteria as compared to fungus to bioleach copper. Additionally, the kinetics and mechanism of copper bioleaching from this e-waste by the chemolithotrophs and heterotrophs were evaluated. The leach liquor obtained from the optimized leaching process was subjected to separation
and purification of copper as >99% pure copper sulfate using Acorga M5640 by solvent extraction.