Bioleaching of Gold and Silver from Waste Printed Circuit Boards by Pseudomonas balearica SAE1 Isolated from an e-Waste Recycling Facility
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Indigenous bacterial strain Pseudomonas balearica SAE1, tolerant to e-waste toxicity was isolated from an e-waste recycling facility Exigo Recycling Pvt. Ltd., India. Toxicity tolerance of bacterial strain was analyzed using crushed (particle size ≤150 µm) waste computer printed circuit boards (PCBs)/liter (L) of culture medium. The EC50 value for SAE1 was 325.7 g/L of the e-waste pulp density. Two-step bioleaching was then applied to achieve the dissolution of gold (Au) and silver (Ag) from the e-waste. To maximize precious metal dissolution, factors including pulp density, glycine concentration, pH level, and temperature were optimized. The optimization resulted in 68.5 and 33.8% of Au and Ag dissolution, respectively, at a pH of 9.0, a pulp density of 10 g/L, a temperature of 30 °C, and a glycine concentration of 5 g/L. This is the first study of Au and Ag bioleaching using indigenous e-waste bacteria and its analysis to determine e-waste toxicity tolerance.
KeywordsBioleaching Pseudomonas balearica Printed circuit boards EC50 Gold Silver
The authors are grateful to DBT (Department of Biotechnology, Ministry of Science & Technology, Govt. of India, Sanction Order No. BT/PR7478/BCE/8/951/2013) for providing financial support. We are also thankful to Exigo Recycling Pvt. Ltd. for gifting e-waste.
Compliance with Ethical Standards
Conflict of interest
Author declares no conflict of interest.
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