The brighter side of e-waste-a rich secondary source of metal.

This article details the electronic waste (e-waste) generation, their composition, health, and environment hazards, and legal rules for disposal as well as their significance as a potential secondary source of metals and other components. Moreover, valuable metal extraction technologies from the e-waste are reviewed in general and waste cell phones in particular. E-waste is nowadays preferentially used for recovery of metals mainly from printed circuit boards (PCBs). Different techniques, namely pyrometallurgy, hydrometallurgy, and biohydrometallurgy used for metal extraction from e-waste are swotted. The economic and environmental valuation features of these technologies are also included. Compared to other methods, biohydrometallurgy is the method of choice, as in it natural components like air and water are used, has low operating and maintenance cost, and operate at ambient temperature and pressure. Microbial aspects of metal extraction from e-waste are summarized.