氧化亚铁硫杆菌浸出污染土中镉的试验研究

Experimental study on removal of cadmium from contaminated soil by Acidithiobacillus ferrooxidans via microbial leaching

微生物浸出法是一种资源节约、低碳环保的土壤修复方法,在重金属污染土壤修复领域颇具前景.通过一系列室内试验研究了氧化亚铁硫杆菌浸出污染土中重金属镉的特性,以期为重金属污染土的修复提供理论依据.通过振荡浸出试验,考虑镉的浓度、能源物质Fe^(2+)的投加量、氧化亚铁硫杆菌的接种量及浸出时间等影响因素,研究了氧化亚铁硫杆菌浸出污染土中镉的特性.结果表明:镉的初始浓度越低,氧化亚铁硫杆菌对镉的浸出率越高.随着浸出时间增加,溶液pH值以及镉的浸出率整体都呈现逐渐升高的趋势.随着Fe^(2+)质量浓度提高,污染土中镉的浸出率呈现先增高后降低的趋势,当Fe^(2+)质量浓度为9 g·L^(−1)时,浸出效果最好.随着氧化亚铁硫杆菌接种量增加,镉浸出效果也随之提高.当营养物质Fe^(2+)的投加量为9 g·L^(−1),氧化亚铁硫杆菌的接种量为25%时,镉的浸出效果最佳,镉初始质量分数100 mg·kg^(−1)的污染土中浸出率可达96.6%.微观测试表明,浸出后土样表面出现新的长条状矿物,土中残留的镉主要为弱酸可提取态与残渣态,可还原态、可氧化态均有所降低.

Microbial leaching is a resource-saving,low-carbon and environment-friendly soil remediation method,and is a promising technique for remediating contaminated soil.The characteristics and leaching mechanism of cadmium leaching from contaminated soil by Acidithiobacillus ferrooxidans were studied through a series of laboratory tests in order to provide theoretical basis for remediation of heavy metal contaminated soil.The characteristics of cadmium leaching from contaminated soil by Acidithiobacillus ferrooxidans were studied by means of oscillatory leaching test,considering the concentration of cadmium,the dosage of energy material Fe^(2+),the inoculation amount of Acidithiobacillus ferrooxidans and the leaching time.The results show that the lower the initial concentration of cadmium in the contaminated soil,the higher the leaching ratio of cadmium.With the increase of leaching time,the pH of solution and the leaching ratio of cadmium in contaminated soil showes a gradually increasing trend.With the increase of Fe^(2+)concentration,the leaching ratio of cadmium in contaminated soil increases first and then decreases.The best leaching effect is achieved when the concentration of Fe^(2+)is 9 g·L^(−1).With the increase of Acidithiobacillus ferrooxidans dosage,the leaching effect increases as well.When the nutrient Fe^(2+)dosage is 9 g·L^(−1),the inoculation amount of Acidithiobacillus ferrooxidans is 25%,the leaching ratio can reach 96.6%when the initial concentration of cadmium is 100 mg·kg^(−1).Microscopic test showed that the new elongated minerals appeared on the surface of the soil sample after leaching,and the residual cadmium in soil were mainly in weak acid extractable and residual state,with much reduced reducible and oxidizable state.