Bioleaching of metals from electronic scrap and its potential for commercial exploitation

In this study, ability of moderately thermophilic bacterial consortium to extract metals from electronic scrap was evaluated using shake flasks and lab-scale column reactor. We investigated the effects of having additional energy source (FeS2, S0, FeS2 + S0), using different consortia of moderately thermophilic bacteria and washing charge material as a pretreatment. At scrap concentrations of 10%, an adapted consortium of Sulfobacillus thermosulfidooxidans and Thermoplasma acidophilum extracted approximately 85% of Cu, 75% of Al, 80% of Ni and 80% of Zn from pretreated electronic scrap with FeS2 + S0 (1%). However, a consortium of S. thermosulfidooxidans and Sulfobacilllus acidophilus, containing FeS2 + S0, extracted 90% of Cu, 80% of Al, 82% of Ni and 85% of Zn.During column bioleaching studies of 165 days, approximately 74% Zn, 68% Al, 85% Cu, 78% Ni was leached out. The results of the leaching process are significant for understanding how to implement these processes on an industrial scale.

► Consortium of autotrophs has greater bioleachability than autotroph + heterotroph.
► Bioleaching efficiency can be improved by additional energy source.
► Compensation of acid demand contributes significantly for maximum metal extraction.
► Current work provides theoretical basis for designing practical bioleaching system.