钙镁离子对酸性煤矿废水中次生铁矿物形成的影响机制及其环境意义

The formation of acidic coal mine drainage, one of the main pollutants in coal mining process, is controlled by the hydrologic aspects of the linked groundwater environment. Acidithiobacillus ferrooxidans adsorbs on coal-pyrite through extracellular polymeric substance (EPS) and bio-oxidation of it is recognized as the main precursor to acidic coal mine drainage generation. On the basis of understanding the seed role of EPS from Acidithiobacillus ferrooxidans on the formation of secondary iron minerals and calcium or magnesium ions can significantly affect the secondary iron minerals synthesis in acidic, sulfate-rich environment, their effects on the secretion of Acidithiobacillus ferrooxidans EPS, EPS molecular weight distribution, and the component constitutes in EPS will be studied in groundwater environment. The influence of EPS characteristics on its adsorption behavior on pyrite will be revealed. The effect of EPS absorbed on the surface of pyrite on secondary iron minerals covers pyrite and reduction acidic coal mine drainage generation will also be investigated. Effects of calcium and magnesium ions on formation of secondary iron minerals in acidic coal mine drainage system and its environmental implications will be clarified from the above data. The results of this study are expected to provide necessary theoretical support for in-depth understanding the actual formation process of acidic coal mine drainage and prevent it at source.

酸性煤矿废水是煤炭开采过程基于地下水环境而形成的主要污染物之一。氧化亚铁硫杆菌通过胞外多聚物吸附于煤系硫铁矿并对其进行生物氧化是酸性煤矿废水产生的主要原因。本项目在认识氧化亚铁硫杆菌胞外多聚物在次生铁矿物形成过程所起晶种作用的基础上，结合钙镁离子能够显著影响酸性硫酸盐体系次生铁矿物形成等相关现象，在地下水环境介质中，分析钙镁离子对氧化亚铁硫杆菌胞外多聚物分泌量、分子量及组分构成等性质的影响规律，探究胞外多聚物性质对其在硫铁矿表面吸附行为的调控作用，揭示吸附于硫铁矿表面不同性质的胞外多聚物对次生铁矿物“包裹”硫铁矿进而抑制酸性煤矿废水产生的作用机理。以期逐步阐明钙镁离子对酸性煤矿废水中次生铁矿物形成的影响机制及其环境意义。研究结果可为深入揭示酸性煤矿废水实际产生过程及对其进行有效源头预防提供必要的理论依据。

本项目在认识Ca2+促进酸性矿山废水Fe2+生物氧化成矿现象的基础上，进一步深入研究了KOH、酸性矿山废水中和残渣，酸性矿山废水中和剂、附着氧化亚铁硫杆菌黄铁矾等物质对酸性矿山废水体系生物成矿的影响。再者，针对次生铁矿物施氏矿物是一种良好的重（类）金属（尤其是砷）吸附材料，探讨了Fe2+生物氧化率、高温改性、施氏矿物合成形态（悬浮态或粘附态）等合成和改性条件对施氏矿物结构特征及除砷能力的影响。此外，针对酸性矿山废水产生本质机理，进一步探究了氧化亚铁硫杆菌密度与养分供给、次生铁矿物包裹硫铁矿对酸性矿山废水产生的影响。给出了次生铁矿物包裹硫铁矿进而抑制酸性矿山废水产生的直接证据。相关研究成果基本揭示出酸性矿山废水体系次生铁矿物的合成行为及其环境意义。