Bioleaching offers a green and sustainable alternative for recovering valuable metals from waste printed circuit boards (WPCBs). This study is the first to use Bacillus thuringiensis, Macrococcus caseolyticus, and Cellulosimicrobium funkei for extracting copper and gold from WPCBs. Two-step bioleaching with C. funkei (with cells) achieved 40 % copper recovery within 3 days, while spent medium bioleaching with B. thuringiensis (cell-free) extracted up to 35 % gold over the same period. To improve gold bioleaching yield, a novel stepwise bioleaching process was developed. In the first step, base metals such as copper were removed using two-step bioleaching with C. funkei for 3 days. The residue was then treated in the second step using spent medium bioleaching with B. thuringiensis, resulting in significantly higher gold bioleaching yield. Pretreatment of WPCBs using ball milling and ozonation further enhanced gold extraction. Metabolomics analysis identified N8-acetylspermidine, a metabolite produced by all tested bacteria, for the first time. However, validation with a commercial N8-acetylspermidine showed this metabolite reduced gold leaching yield by the reduction of gold ions. These findings provide valuable knowledge for advancing bioleaching processes for metal recovery from WPCBs, particularly the negative effect of N8-acetylspermidine on elemental leaching, which has not been reported previously.

中文翻译：

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废印刷电路板中铜和金的强化生物浸出：逐步过程、预处理策略、代谢组学分析和 N8-乙酰亚精胺的作用


生物浸出为从废弃印刷电路板 （WPCB） 中回收有价金属提供了一种绿色和可持续的替代方案。这项研究是首次使用苏云金芽孢杆菌、溶酪芽球菌和丰景纤维素微球菌从WPCBs中提取铜和金。使用C. funkei（含细胞）的两步生物浸出在3天内实现了40%的铜回收率，而使用苏云金芽孢杆菌（无细胞）的用过培养基生物浸出在同一时期提取了高达35%的金。为了提高金生物浸出率，开发了一种新的逐步生物浸出工艺。第一步，使用 C. funkei 的两步生物浸出 3 天去除铜等贱金属。然后在第二步中使用用过的培养基对苏云金芽孢杆菌进行生物浸出处理残留物，从而显著提高金生物浸出率。使用球磨和臭氧化对 WPCB 进行预处理进一步增强了黄金提取。代谢组学分析首次确定了 N8-乙酰亚精胺，这是所有测试细菌产生的代谢物。然而，用市售 N8-乙酰亚精胺进行的验证表明，这种代谢物通过减少金离子来降低金浸出率。这些发现为推进从 WPCBs 中回收金属的生物浸出工艺提供了宝贵的知识，特别是 N8-乙酰亚精胺对元素浸出的负面影响，这在以前没有报道过。