生物淋洗修复钒污染土壤的性能与机理研究

Performance and mechanism of bioleaching remediation of vanadium contaminated soil

摘要:

【目的】土壤重金属污染问题日益受到关注，其中钒污染逐渐成为研究热点。淋洗是土壤修复的重要手段，但存在污染大、成本高的缺点。生物淋洗技术因其经济高效且环保的特点能够应用于土壤的修复，但其对钒污染土壤的修复，认识仍非常有限。【方法】本研究采用嗜酸性氧化亚铁硫杆菌对钒污染土壤进行了生物淋洗试验，通过影响因素试验探究了钒的最佳浸出条件，并应用扫描电子显微镜-能量色散X射线谱分析了钒在淋洗过程中的变化，最后对代谢产物进行了解析。【结果】微生物次生代谢产物能促进土壤中钒的溶出。氧化亚铁硫杆菌对土壤钒的浸出效率较高，生物淋洗20 d后土壤中钒的浸出率达到27.4%，进一步的影响因素试验表明，在固体浓度为3%、接种体积为10%、初始pH值为1.8、初始Fe²⁺的浓度为3.0 g/L的条件下，土壤中钒的浸出效果最佳。SEM-EDS分析证实生物淋洗后土壤中钒含量减少，其中以非残渣态形式存在的钒更容易被浸出。代谢组学分析显示氧化亚铁硫杆菌在浸出过程中产生了大量代谢产物来应对重金属胁迫。【结论】生物淋洗技术能够有效地实现土壤钒污染的修复，本研究为钒污染土壤提供了一种环境友好的修复方式。

Abstract:

[Objective] Soil contamination by heavy metal is a growing concern, of which vanadium is gradually becoming a research hotspot. Although leaching is an important tool for soil remediation, it can cause severe pollution and incur high cost. Bioleaching can be applied as an efficient soil remediation process because of its cost-effective and environmental- friendliness. However, current understanding of remediation of vanadium-contaminated soil is still limited. [Methods] In this study, we applied Acidithiobacillus ferrooxidans in the bioleaching of vanadium-contaminated soil. The optimal leaching conditions were investigated by changing the influencing factors. The scanning electron microscopy and energy dispersive X-ray spectroscopy were applied to analyze the changes of vanadium during the bioleaching process. The microbial metabolites were characterized. [Results] The microbial secondary metabolites could promote the leaching of vanadium from the soil. The leaching efficiency of vanadium from soil by Acidithiobacillus ferrooxidans was high, and the leaching rate of vanadium from soil reached 27.4% after 20 days. Further experiments on the influencing factors showed that the best leaching of vanadium from soil was achieved at a solid concentration of 3%, an inoculum volume of 10%, an initial pH of 1.8 and an initial Fe²⁺ concentration of 3.0 g/L. SEM-EDS analysis confirmed the reduction of vanadium content in the soil after leaching, and analysis of the vanadium morphology in the soil indicated that the vanadium present in the non-residue form in the soil was more easily leached. Metabolomic analyses showed that Acidithiobacillus ferrooxidans produced a large number of metabolites during the leaching process to cope with the high concentration of heavy metals in the environment. [Conclusion] The bioleaching technology can effectively remediate vanadium-contaminated soil. This study provides an environmentally friendly remediation approach for the restoration of vanadium-contaminated soil.