底物优化酸性矿山废水生物修复系统的抗冲击性能及微生物响应机制

Acid mine drainage (AMD), characterized by low pH, high concentrations of sulfate and dissolved metals, has been recognized as a primary pollution source for receiving watersheds and eco-systems in mining areas. The choice of organic substrate and activity of key functional microorganisms under different shock loads are crucial for efficient and stable remediation of AMD. By monitoring the performance of sulfate-reducing continuous flow columns featuring different substrate combinations of spent mushroom compost and crab shell, co-efficiency and remediation capacity of the organic substrates will be calculated and the optimal substrate combination will be selected. Mechanism for acidity neutralization, sulfate reduction and metal removal will be analyzed so as to demonstrate effects of different shock loads on system stability. By applying metagenomics and real-time quantitative PCR techniques, both structural and quantitative analyses of microbial community under shock loads will be carried out to investigate microbial dynamic variations. Moreover, through the sequencing of overall transcriptomes, differential gene expression levels will be evaluated, and microbial response under different environmental loads are to be speculated. The proposed study aims to find out key factors affecting system performance and corresponding microbial control mode, and finally, to decontaminate AMD economically and efficiently and reduce its negative ecological effects.

酸性矿山废水（AMD）因其低pH、高硫酸盐和高溶解态金属浓度等特性，成为矿区水体污染和生态破坏的首要因素。利用被动式生物修复系统处理AMD的过程中，有机底物的选择与冲击负荷下微生物种群的代谢活性是系统高效、稳定运行的关键。本项目以硫酸盐还原连续流柱反应器为载体，考察不同质量配比的蘑菇渣堆肥与虾蟹壳底物组分的处理效率、容量与经济成本，筛选最优底物；监测不同冲击负荷对系统稳定性影响，分析酸度中和、硫酸盐还原与金属迁移转化作用机理；利用宏基因组与荧光定量PCR技术对不同冲击负荷下微生物群落进行定性与定量分析，探索其动态变化规律；通过转录组测序，分析基因差异表达，解析微生物在环境胁迫下的响应机制；最终找出影响系统处理效果的关键环境因素和与之对应的微生物调控模式，从而为经济有效地解决AMD污染问题提供一种科学思路，以削减矿区生态负效应。

针对酸性矿山废水（AMD）生物修复中提高处理效能与降低经济成本的实际需求，本项目首先实地考察了矿区AMD的污染特性及其对流域微生物生态的影响。基于矿区AMD的平均污染水平，以不同质量配比的虾蟹壳（CS）和秸秆堆肥（SCP）为有机填料，成功构建了九组连续流柱反应器，全面、系统考察了不同底物组合对AMD的净化效果和处理容量，核算了其经济成本，筛选出了最优底物组合；探明了AMD处理系统的金属去除机制，通过高通量测序分析揭示了其微生物驱动与调控机制；最后阐释了反应器有机填料组分、功能菌群和处理效能的关联性，明确了影响AMD生物修复效果的关键瓶颈因素。主要研究结果表明，所选矿区AMD流域表层水的锰污染程度最高，而铜和镉在底泥中的污染累积效应最强，需要在AMD修复实践中重点关注；此外，AMD污染降低了流域底泥的微生物种群多样性，从而使微生物生态系统更加脆弱。连续流柱反应器填料层中CS含量越高，其处理效能越佳，本实验条件下的最佳有机填料组合初步确定为90%CS + 10%SCP。系统中溶解态金属的去除主要通过（共）沉淀和/或有机填料的吸附作用，以硫化物和氢氧化物沉淀为主，具体机制与金属种类流域、系统碱度和底物组分相关。AMD生物修复系统中CS含量越高，对微生物菌种的选择性富集效应越强，关键功能菌属的相对丰度越高；而进水酸度是影响系统出水水质的重要因素之一。从本质上说，Cellulomonas、Acetobacteroides和硫酸盐还原三大优势菌属分别占据了微观功能生态位的上、中、下游，对AMD处理效能起着调控作用，而虾蟹壳材料的投加为该类优势功能菌属提供了充足碱度与缓释碳氮源，创造了最适于其生长代谢的微观环境，从而提升了AMD处理系统的净化效果与处理容量，降低了系统运行成本。所获结果可为AMD原位生物修复工艺的进一步优化和应用提供指导方向与理论基础，从源头上防控矿区水体生态失衡。