VATIS UPDATE Article

A team of researchers led by Antonio David Dorado, Montserrat Solé and Xavier Gamisans at the Department of Mining, Industrial and ICT Engineering (EMIT) of the Universitat Politècnica de Catalunya (UPC), Spain, are exploring the potential of bioleaching as a technique for recovering metals from electronic waste from mobile phones. The technique could easily be adapted for use with other kinds of electronic waste, such as televisions, computers and refrigerators. ‘Bioleaching’, a process in which microorganisms feed on the metal in the circuit boards of mobile phones to eliminate what has no value and recycle recoverable metals.

The process involves putting electronic waste containing metals of interest – copper, gold, chromium, zinc, nickel and aluminium, among others – in contact with iron-oxidising bacteria to extract the metals for reuse. Instead of chemically attacking the waste, the process harnesses the oxidising ability of some microorganisms. The extraction agents used are regenerated, and use of reagents and high temperatures is reduced. The process is starting to be used with printed circuit boards from mobile phones, but experts say it could easily be adapted for use with other kinds of electronic waste, such as televisions, computers and refrigerators.

The most commonly used bacterial species, Acidithiobacillus ferrooxidans, grows in very adverse (and uncommon) conditions. It is found in nature in environments such as urban waste water. The researchers collected samples from such environments and treated them in a laboratory under conditions designed to ensure that only this species would survive and reproduce. Other microorganisms and communities that are generating good results within a reasonable time frame are also being investigated. At this point, the researchers are trying to work out how the extraction process can be improved to make it viable for industrial use.