Computer circuit boards are a major electronic waste containing higher concentrations of copper, gold and silver. These metals may be recovered by bioleaching, an eco-friendly process to recover metals from natural ores. However, the application of the bioleaching to electronic waste is still in the infancy stage. Here, the bioleaching capability of Acidithiobacillus ferrooxidans to extract copper from printed circuit boards was investigated at laboratory scale using shake flasks. The effect of initial pH, amount and size of printed circuit boards, and volume of inoculum on copper dissolution rates were evaluated. Results show that the highest dissolution rate of 32.44% was achieved after 7 days of leaching at initial pH 2.0, 10 g/L of waste printed circuit board, 40% v/v of inoculum for 1 mm size of circuit board. The smallest size of 1 mm induces the higher dissolution rates, which is explained by higher surface area and thus better bacterial adhesion. Also, the copper dissolution rates increase with the inoculum volume. Overall, bioleaching of copper from waste printed circuit boards using Acidithiobacillus ferrooxidans is achievable.

中文翻译：

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铁氧化酸性硫杆菌增强了计算机废物电路板上铜的生物浸出

计算机电路板是一种主要的电子废物，其中含有较高浓度的铜，金和银。这些金属可以通过生物浸提法回收，这是一种从天然矿石中回收金属的环保工艺。但是，将生物浸出技术应用于电子废物仍处于起步阶段。在这里，酸性氧化硫硫杆菌的生物浸出能力实验室规模的摇瓶研究了从印刷电路板上提取铜的方法。评估了初始pH，印刷电路板的数量和大小以及接种量对铜溶解速率的影响。结果表明，对于初始尺寸为1 mm的电路板，在初始pH 2.0浸出7天，10 g / L的废印刷电路板，40％v / v的接种物后，浸出7天可获得最高的溶解度。1 mm的最小尺寸会导致较高的溶出速率，这可以通过较高的表面积和更好的细菌附着力来解释。而且，铜的溶解速度随着接种量的增加而增加。总体而言，使用酸性氧化铁硫杆菌从废印刷电路板中进行铜的生物浸出是可以实现的。