Abstract End-of-life vehicles are usually crushed in large scaled shredders in order to increase the surface area for further processing. During the shredding process, the so-called shredder-light-fraction (SLF), containing mainly plastics and other synthetic polymers, is discharged. However, this fraction still contains up to 20% metals such as iron (Fe), copper (Cu), nickel (Ni) and zinc (Zn), making them an interesting substrate for bioleaching and source of high-value metal traces. To develop a bioleaching process for metal recovery from shredded fractions, two experimental approaches including a heap- and a stirred-tank reactor were tested. The acidophilic, iron- and sulfur-oxidizing bacteria Acidithiobacillus ferrooxidans and the iron-oxidizing bacteria Leptospirillum ferrooxidans were investigated as pure and co-culture for their ability to solubilize trace metals. A. ferrooxidans proofed to be the more suitable bioleaching organism resulting in leaching efficiencies of up to 100% for Zn and Ni in batch experiments. Furthermore, in the stirred-tank reactor using A. ferrooxidans about 100, 80 and 55% of Cu, Zn and Ni have been recovered from 50 g l−1 of the SLF, respectively. Bioleaching of 3000 g SLF in the heap-reactor resulted in a recovery of about 100% Zn, 60% Cu and ~ 55% Ni after 33 days without the need of external sulfuric acid addition for pH regulation. The high leaching efficiencies in both experimental setups confirmed the potential of bioleaching for a sustainable metal recovery from shredder residues (i.e. SLF) making it a profitable, eco-friendly alternative to conventional chemical leaching processes.

中文翻译：

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嗜酸细菌对粉碎轻馏分 (SLF) 的搅拌槽和堆生物浸出

摘要 报废车辆通常在大型粉碎机中粉碎，以增加表面积以进行进一步加工。在粉碎过程中，会排出所谓的粉碎机轻馏分 (SLF)，主要包含塑料和其他合成聚合物。然而，这一部分仍然含有高达 20% 的金属，如铁 (Fe)、铜 (Cu)、镍 (Ni) 和锌 (Zn)，使它们成为生物浸出的有趣基质和高价值金属痕量的来源。为了开发从碎屑中回收金属的生物浸出工艺，测试了两种实验方法，包括堆和搅拌罐反应器。嗜酸性，铁和硫氧化细菌亚铁氧化酸硫杆菌和铁氧化细菌钩端螺旋体亚铁氧化细菌被研究为纯的和共培养的，因为它们具有溶解痕量金属的能力。A. ferrooxidans 被证明是更合适的生物浸出生物，在批量实验中，锌和镍的浸出效率高达 100%。此外，在使用 A. ferrooxidans 的搅拌釜反应器中，分别从 50 g l-1 的 SLF 中回收了大约 100%、80% 和 55% 的 Cu、Zn 和 Ni。在堆反应器中对 3000 克 SLF 进行生物浸出，33 天后回收了约 100% 的锌、60% 的铜和约 55% 的镍，而无需添加外部硫酸来调节 pH 值。