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

Abhilash Abhilash,Pratima Meshram,Anirban Ghosh,Eric D Van Hullebusch,Shirin Tabassum

doi:10.3390/met11020317

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.

Highlights

In the modern-day, printed circuit boards (PCBs) are the key component for all electronic companies
India has 178 formal e-waste recycling/dismantling units recognized by Central Pollution Control Board (CPCB), using automated, semi-automated, or manual operations; these are located in different states
The ability of acidophilic chemo-lithoautotroph bacteria, A. ferrooxidans, and A. thiooxidans were tested for the extraction of metals from waste shredded printed circuit boards

Summary

Introduction

In the modern-day, printed circuit boards (PCBs) are the key component for all electronic companies. World demand for copper is projected as 765 Mt until 2044 at 1.9% annually. India generates nearly 7.17 Mt of hazardous waste annually, with waste electrical and electronic equipment (WEEE) contributing 10–15%, and currently, nearly 2.0 Mt of accumulated EWastes in India (fourth globally). India has 178 formal e-waste recycling/dismantling units recognized by Central Pollution Control Board (CPCB), using automated, semi-automated, or manual operations; these are located in different states. These units are not engaged in the extraction of metals and function as dismantlers for manual separation of components and selling to recyclers outside the country [5,6]

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