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

Abstract

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.

Progress in bioleaching: part B, applications of microbial processes by the minerals industries

“…However, this topic was already raised on the first International Biohydrometallurgy Symposium (IBS) 45 years ago (Ebner 1977 ). Especially, biohydrometallurgy for PCB processing has been development in laboratory scale bioreactor experiments over the last years, and, e.g., up to over 90% of copper recovery has been achieved (Hubau et al 2020 ; Monneron-Enaud et al 2020 ; Abhilash et al 2021 ; Iglesias-González et al 2022 ). Metal recycling based on biotechnology will raise increasing interest in future including economic and environmental process considerations such as energy consumption and carbon footprint.…”

Preliminary Bioleaching Experiment of E-Waste

“…Bioleaching methods are based on the application of the sulphur compounds oxidizing bacteria and microorganisms. The most commonly used microorganisms in bioleaching are iron-and sulphur-oxidizing chemolithotrophic bacteria (Acidithiobacillus ferrooxidans, A. thiooxidans, Leptospirillum ferrooxidans, Ferrobacillus), cyanogenic bacteria (Chromobacterium violaceum), moderately thermophilic bacteria (Sulfobacilllus thermosulfidooxidans, Thermoplasma acidophilum, S. thermosulfidooxidans), heterotrophic bacteria (Sulfolobus, Bacillus, Pseudomonas) and microscopic fungi (Aspergillus niger, A. ficuum and Penicillium simplicissimum) [13,14,18,21,22,37,38,39,40,41].…”