Ecological Engineering & Environmental Technology (Nov 2021)
Metal Mobilisation from Obsolete PCB of Mobile Phones Using Chemolithotrophs
Abstract
Tech is ubiquitous and a major mushrooming stream of hazardous material into the environment produced from the obsolescence of electronic equipment. The successful commercial operations of bioleaching processes from ores are now finding urban mines to be its potential source of base metals and precious metals. Among the six categories of e-waste, mobile phones pose a significant challenge due to the technological up-gradation and short life span of these gadgets. Thus, this study has precisely projected towards e-waste generated by mobile phones. The ICP-OES analysis of 0.5mm particle size of e-waste revealed, the presence of base metals Co < Mg < Pb < Zn < Ni < Al < Cu and precious metals Pt < Au. The analysis showed among base metals Cu to be present in highest concentration i.e., 244.303 g/ Kg and gold to be present as 1106.6 mg/Kg. In the current study, the plausibility of bioleaching processes using chemolithotrophs (Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans) for mobilization of metals from e- waste was experimented at variable pulp densities (0.5%, 1%, 1.5% and 2%). Results from the study indicated that the pure cultures of Acidithiobacillus ferroxidans and Acidithiobacillus thiooxidans were able to abundantly leach out base and precious metals at 0.5% and 1% pulp densities of powdered e-waste. At 1% pulp density, Acidithiobacillus ferroxidans leached 79% of Cu and at 0.5% Ni and Al were leached as 80% and 70% respectively. Acidithiobacillus thiooxidans at 0.5% pulp density leached out Co, Zn and Pb as 61.7%, 60.9%, and 49.8% respectively. Among precious metals at 1% pulp density Acidithiobacillus ferrooxidans leached out Au as 55% and Acidithiobacillus thiooxidans as 67%. These findings highlight the potential application of biomining for mobilization and extraction of metals from electronic waste.
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