Bioleaching Copper From E-waste With Shewanella Oneidensis
Electronic waste (e-waste) contains many valuable metals in abundance, especially copper. Traditional methods of metals extraction present environmental and human health hazards, including high energy consumption, heavy metal pollution, and production of dangerous fumes. However, certain bacteria can remove metals from ores as complex as e-waste just by breathing. Shewanella oneidensis is an iron-reducing bacterium that has potential applications to metals extraction, as it is capable of leaching metals by using them as terminal electron acceptors during anaerobic respiration. This project investigates the application of S. oneidensis to copper extraction from e-waste. Printed circuit boards (PCBs) were shredded for experimental use and the metals content was determined using nitric acid digestion and ICP-OES analysis. S. oneidensis’ ability to survive in contact with potentially toxic e-waste, as well as its leaching potential was determined using bioleaching experiments. This was done by inoculating liquid LB medium with both S. oneidensis and shredded circuit boards. Leaching experiments with pure copper (as CuSO4) were performed to compare results. ICP-OES and flame AAS analysis of all experiments found a significant decrease in the aqueous copper concentration in the biotic sample, indicating possible bioaccumulation of copper in the cells. In addition, the cells were found to be viable despite extended contact with e-waste. While the overall mass of copper removed was very small, this shows that S. oneidensis is capable of reducing copper from e-waste and could be used to remove that copper for e-waste mining purposes with further process optimization.