Bioleaching of copper from waste printed circuit boards by bacterial consortium enriched from acid mine drainage

• Published in: Journal of hazardous materials Vol. 184; no. 1-3; pp. 812 - 818
• Main Authors: Xiang, Yun, Wu, Pingxiao, Zhu, Nengwu, Zhang, Ting, Liu, Wen, Wu, Jinhua, Li, Ping
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.12.2010; Elsevier
• Subjects: Acid mine drainage; Acids; Applied sciences; Bacteria; Bacteria - growth & development; Bacteria - metabolism; Bacterial consortium; Bacterial leaching; Bioleaching; Boards; Chemical engineering; CIRCUIT BOARDS; Copper; Copper - metabolism; Enrichment; Exact sciences and technology; EXTRACTIVE METALLURGY; Ferrous Compounds - chemistry; Hydrogen-Ion Concentration; Leaching; MICRO ORGANISMS; MINE WASTES; Mining; POLLUTION; PRINTED CIRCUITS; Reactors; Waste printed circuit boards; Wastes; Water Microbiology; Waste printed circuit boards; Bioleaching; Bacterial consortium; Copper; Acid mine drainage; Iron II; Solubility; Polychlorobiphenyls; Bacterial leaching; Powder; Iron III; pH; Bacteria; Oxidation
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2010.08.113

The objectives of this study were to evaluate the solubility of copper in waste printed circuit boards (PCBs) by bacterial consortium enriched from natural acid mine drainage, and to determine optimum conditions of bioleaching copper from PCBs. The results indicated that the extraction of copper was mainly accomplished indirectly through oxidation by ferric ions generated from ferrous ion oxidation bacteria. The initial pH and Fe2+ concentration played an important role in copper extraction and precipitate formation. The leaching rate of copper was generally higher at lower PCB powder dosage. Moreover, a two-step process was extremely necessary for bacterial growth and obtaining an appropriate Fe2+ oxidation rate; a suitable time when 6.25g/L of Fe2+ remained in the solution was suggested for adding PCB powder. The maximum leaching rate of copper was achieved 95% after 5 days under the conditions of initial pH 1.5, 9g/L of initial Fe2+, and 20g/L of PCB powder. All findings demonstrated that copper could be efficiently solubilized from waste PCBs by using bacterial consortium, and the leaching period was shortened remarkably from about 12 days to 5 days.