Bioleaching of metal concentrates of waste printed circuit boards by mixed culture of acidophilic bacteria

► Metal concentrates of waste PCBs were used as the substrate instead of scraps or PCBs powder. ► A two-step bioleaching process achieved 96.8% copper leaching efficiency in 45 h, and around 90% aluminum and zinc in 98 h. ► Bioleaching period was shorten from about 8 days to 45 h in a two-step process under the optimum conditions.