(35e) Bioleaching of Metals from Electronic Waste

Estimates suggest that electronic waste is being generated two to three times faster than other waste streams. Estimates also suggest that between 2000 and 2007 about 500 million computers became obsolete and were discarded. Printed circuit boards are the essential components of most electronic waste, and metals in printed circuit boards are potentially toxic; when not disposed of properly, these metals can leach into soil and water and seep into watersheds. Chemical leaching has been the most commonly used method to extract these metals from waste.

Bioleaching is the extraction (mobilization) of metals from materials by microorganisms. In this study we have investigated the bioleaching of metals from computer circuit boards using Acidiphilium acidophilum. Batch cultures of A. acidophilum were exposed to different concentrations of shredded printed circuit boards; the amounts of copper, zinc, aluminum and nickel released into the culture medium were measured by inductively coupled plasma mass spectrometry. Our preliminary results indicate that A. acidophilum bioleach copper and aluminum from printed circuit boards, thus offering an alternative approach to chemical leaching; the results for zinc and nickel are inconclusive at this point.