Microbiological leaching of metals and its recovery from waste electrical and electronic equipment: A review

Abstract

Electronic waste or waste electrical and electronic equipment (WEEEs) is an emerging and fast-growing waste stream with complex characteristics. As per United Nations 'Global E-waste Monitor report, 2015' (Baldé et al., 2014), the global quantity of total e-waste generated in 2014 was around 41.8 million metric tonnes (MT). The presence of metals like copper, aluminium, iron and various precious metals like gold, silver, palladium, platinum, etc., in high concentrations, made e-waste an 'urban mine'. Bioleaching is one of the successful bio-hydrometallurgical method, which can be employed for metal recovery from different WEEEs. Recovery of precious metals like copper, gold and silver is possible at high concentrations from WEEEs using acidophilic mesophiles and thermophiles and some fungal species. The current paper mainly aims to reflect on e-waste generation, mechanisms of bioleaching and various microorganisms employed for the extraction of metals from the electronic waste.