Two-step bioleaching of copper and gold from discarded printed circuit boards (PCB).

Waste management (New York, N.Y.)

PubMedID: 26704063

Isildar A, van de Vossenberg J, Rene ER, van Hullebusch ED, Lens PN. Two-step bioleaching of copper and gold from discarded printed circuit boards (PCB). Waste Manag. 2015;.
An effective strategy for environmentally sound biological recovery of copper and gold from discarded printed circuit boards (PCB) in a two-step bioleaching process was experimented. In the first step, chemolithotrophic acidophilic Acidithiobacillus ferrivorans and Acidithiobacillus thiooxidans were used. In the second step, cyanide-producing heterotrophic Pseudomonas fluorescens and Pseudomonas putida were used. RESULTS
showed that at a 1% pulp density (10g/L PCB concentration), 98.4% of the copper was bioleached by a mixture of A. ferrivorans and A. thiooxidans at pH 1. 0-1. 6 and ambient temperature (23±2°C) in 7days. A pure culture of P. putida (strain WCS361) produced 21. 5 (±1. 5)mg/L cyanide with 10g/L glycine as the substrate. This gold complexing agent was used in the subsequent bioleaching step using the Cu-leached (by A. ferrivorans and A. thiooxidans) PCB material, 44. 0% of the gold was mobilized in alkaline conditions at pH 7. 3-8. 6, and 30°C in 2days. This study provided a proof-of-concept of a two-step approach in metal bioleaching from PCB, by bacterially produced lixiviants.