Bacteria speed recovery of precious metals from automotive catalysts

Clean, cheap way to recover valuable metals from industrial wastes is a world first for Birmingham, UK research team



Bacteria could soon have a major role to play in recycling precious metals from spent automotive catalysts and other industrial wastes. Scientists at the University of Birmingham have made a patent application for a new process in which the tiny organisms get to work recovering the valuable materials more quickly and cheaply than conventional methods.



In the automotive industry, the technology could help to overcome future shortages and increased prices of platinum group metals (PGMs) as demand outstrips supply. The technology integrates metal removal from spent automotive catalysts and PGM recovery in a simple process.



Research was carried out as part of a major waste minimisation initiative backed by government and industry. The WMR3 programme (Waste Minimisation through Recycling, Re-Use and Recovery in Industry) is spearheading new ways to clean up the environment and make better use of resources. The research project tested a novel reactor in which bacterial action speeds up metal recovery by up to 50%.



‘This new technology is a world first and it represents a very significant advance in recovery of platinum group metals,’ says Professor Lynne Macaskie, leading investigator at the University of Birmingham School of Biosciences. ‘Bacteria make the process quicker and faster, and that gives us a real edge when it comes to recovering these valuable, strategic metals.’



Today’s catalysts last for around 50,000 miles. Increasing numbers are now being scrapped but recovering the tiny content of PGMs is difficult and expensive using conventional recycling technology. In the UK, most spent catalysts are treated in furnaces with other scrap material or shipped overseas for recycling.



To find a better solution, three departments at Birmingham collaborated with industrial partners in the three-year project. Specialists from the schools of Biosciences, Chemical Engineering and Metallurgy & Materials Science received support from EA Technology (now called C-Tech Innovation Ltd) and test samples from Degussa. An initial grant of £192,000 and an additional £252,000 for follow-up studies were awarded by the Engineering and Physical Sciences Research Council.



A key advance is a type of electrochemical cell, known as an electrobioreactor, for which patent application has been made. It resembles a hollow pencil, whose outer casing supports the bacteria. When the ‘pencil’ is immersed in a continuous flow of waste, metal is deposited onto the cell walls of the bacteria. If left to build up, the deposit will drop off to the bottom of the vessel from where it can be recovered.



Follow-up studies showed that palladium that has been ‘biorecovered’ in this way performs better as a catalyst than its chemical counterpart. It can even treat pcbs (polychlorinated biphenyls), a major environmental pollutant, which chemically prepared palladium is unable to do.



Further research is now being carried out by two EU-funded research projects and a Faraday partnership between Birmingham, Imperial College and Cambridge Universities, together with C-Tech Innovation, working with a network of companies with waste problems.



Applying ISWM to the electronic waste material stream – in Latin America



The Urban Waste Expertise Programme (UWEP), an eight-year Dutch research and pilot project programme (1995-2003) on urban waste in the South is coordinated by WASTE and funded by the Netherlands Agency for International Cooperation (DGIS), Ministry of Foreign Affairs.



In February 2003, WASTE together with its Costa Rican counterpart, ACEPESA, started a one year project, which applies the ISWM methodology to the Waste Materials Stream from Electronic and Electric Equipment (WEEE) in Costa Rica and The Netherlands.



This project “Design of an ISWM