A Microbial System for Recovering Noble Metals in Urban Mining

钯的微生物减少和恢复在25 ° C和pH值7中使用了在批处理和连续流动的粘性罐反应器中使用金属离子减少细菌的谢瓦内拉藻类的静止细胞。对钯进行的生物教育恢复是一个快速的过程：在批处理反应器的60分钟操作中， 1-10 mol/m^3相对钯（II）完全减少到小于10纳米的晶体纳米颗粒。10摩尔/m^3 （1060 ppm）的微恢复容量演示了与细菌细胞中的微沉积的570-折叠的PdCl 2解决方案。在一个连续的流动反应堆中，钯恢复的速率达到最大95公斤/（h·m^3）当空间时间非常短，说，20年代。黄金的快速生物教育沉积（三）也在酸性条件下得到了证实。pH值为2.0，较大的黄金颗粒大约在350纳米，尺寸是沉积的提取物。该概念已成功地应用于恢复从电子碎片中选择性的酸性皮革（百万分之200的黄金（III））的黄金。我们进一步提出了一个概念性的流程表，用于从电子废物中进行贵族金属的微回收。我们坚信，微生物恢复是一个非常有吸引力的系统，可以在城市采矿中回收高贵的金属。

Microbial reduction and recovery of palladium was achieved at 25℃ and pH 7 using resting cells of the metal ion-reducing bacterium Shewanella algae in batch and continuous-flow stirred tank reactors. The bioreductive recovery of palladium with formate was a fast process : Within 60 min operation of batch reactor, 1-10 mol/m^3 aqueous palladium(II) ions were completely reduced to crystalline nanoparticles of less than 10 nm in size. The microbial recovery capacity demonstrated that the 10 mol/m^3 (1060 ppm) aqueous PdCl2 solution was concentrated up to 570-fold by the microbial deposition in the bacterial cells. In a continuous-flow reactor, the rate of palladium recovery reached a maximum of 95 kg/(h・m^3) when the space time was very short, say, 20s. Fast bioreductive deposition of gold(III) was also achieved even under acidic conditions. At pH 2.0, larger gold particles approximately 350 nm in size were deposited extracellularly. The concept was successfully applied to recover selectively gold from acidic leachate (200 ppm of gold(III)) from electronic scraps. We furthermore proposed a conceptual flow sheet for the microbial recycling of noble metal from electronic waste. We strongly believe that the microbial recovery is extremely attractive system for recycling noble metals in urban mining.