Bioleaching of Copper from Electronic Waste Using Aspergillus niger

Abstract

The recycling of printed circuit boards (PCBs) causes environmental problems by releasing dioxins and furans. The objective of this study is the recovery of copper from PCBs through the bioleaching process using Aspergillus niger which was isolated from the surface of Abu Tartur phosphate. In the bioleaching process, the optimum conditions were used to modify ammonium medium with inoculum spore size are 2Χ106 SFU/50 ml for 5 days at 30ͦ C in a pulp of 0.5% solid 150 mesh particle size and aeration at 200 rpm. Different carbon and nitrogen sources were used. Glucose (1.5%) and ammonium chloride (0.2%) were the best source of carbon and nitrogen, respectively. Also, the optimum initial medium’s pH was 7. At these conditions, about 100% of Cu was extracted. The mechanism of bioleaching was studied by detecting the production of organic acid through using brome cresol green as an indicator and HPLC analysis. The color change of agar medium of the incubated plate with A. niger from blue to yellow, and HPLC analysis showed detection malic and citric acids in the sample in presence e-waste higher than the sample without e-waste. E-waste before and after the bioleaching process was investigated using SEM. The surface of e-waste becomes more smooth and porous due to the bioleaching process.