Park Hyun-Sung, Lee Jong-Un, Ahn Jae-Woo
Microbial Geochemistry Lab, Department of Geosystem Engineering, Chonnam National University, Gwangju, 500-757, Korea.
Environ Geochem Health. 2007 Aug;29(4):303-12. doi: 10.1007/s10653-007-9095-z.
Bioleaching from soil artificially contaminated with analogues of radionuclides, Co and Sr, was carried out using a Fe-oxidizing bacterium, Acidithiobacillus ferrooxidans. Due to bacterial metabolism, the pH and dissolved Fe(3+) concentration in a biotic slurry decreased and increased respectively, over time, but the concentrations of Co and Sr extracted from the soil showed no significant enhancement compared with those under abiotic control. In both cases, Co and Sr were leached from the soil during the initial period of the experiment, due to the initially low solution pH of 2.0, and the dissolved concentrations remained almost constant for the duration of the experiment (300 h). Since oxidation of Fe(2+) by A. ferrooxidans led to the production of Fe precipitates and colloidal suspensions, the Co and Sr extracted into solution were most likely re-adsorbed onto the Fe solids. Also, A. ferrooxidans, without an external supply of Fe(2+), extracted almost equal or greater amounts of Co and Sr from the soil than when Fe(2+) was supplied. Under the same leaching conditions, the extent of Sr removal was much lower than that of Co. On the contrary to the high efficiency of microbial metal leaching in biohydrometallurgy for low-graded sulfide ores, which has been widely documented, conventional bioleaching techniques with A. ferrooxidans supplied with enough Fe(2+) showed low efficiency for the removal of radionuclides loosely bound onto soil particle surfaces.
利用铁氧化细菌氧化亚铁硫杆菌对人工受放射性核素类似物钴和锶污染的土壤进行生物浸出。由于细菌代谢，随着时间的推移，生物泥浆中的pH值和溶解的Fe(3+)浓度分别降低和升高，但与非生物对照相比，从土壤中提取的钴和锶的浓度没有显著提高。在这两种情况下，由于实验初始阶段溶液pH值较低（2.0），钴和锶在实验初期从土壤中浸出，并且在实验持续时间（300小时）内溶解浓度几乎保持不变。由于氧化亚铁硫杆菌将Fe(2+)氧化导致产生铁沉淀物和胶体悬浮液，因此提取到溶液中的钴和锶很可能重新吸附到铁固体上。此外，在没有外部供应Fe(2+)的情况下，氧化亚铁硫杆菌从土壤中提取的钴和锶几乎与供应Fe(2+)时相等或更多。在相同的浸出条件下，锶的去除程度远低于钴。与生物湿法冶金中低品位硫化矿微生物金属浸出的高效率（已被广泛记录）相反，向氧化亚铁硫杆菌供应足够Fe(2+)的传统生物浸出技术对去除松散结合在土壤颗粒表面的放射性核素效率较低。
