地下水PAHs在生物炭-降解菌耦合PRB中的传质降解及微生物响应研究

Remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated groundwater is a major environmental concern worldwide. Bioaugmented permeable reactive barrier (Bio-PRB) has received more attention because it is very cost-effectiveness and environmentally friendly. In a Bio-PRB system, the attenuation of contaminants is affected by different processes, including contaminant sequestration (sorption), biodegradation to less hazardous form, mass transfer in porous media. Therefore, it is of practical significance to study the interactions among these processes, to maintain the sustainability and stability of a Bio-PRB groundwater remediation system. The objective of this research is to study the effect of microbial community on the transfer and degradation of phenanthrene in a bench-scale Bio-PRB system. The degradation characteristics of phenanthrene using biochar immobilized dominant microorganism will be studied in batch experiment to establish its biodegradation kinetics model. The response mechanism of microbial communities to environmental factors in the remediation process will also be investigated. Furthermore, the interrelation between mass transfer of phenanthrene and microbial communities will be explored. Coupling the decay coefficient obtained with equations of diffusion, adsorption and desorption, and biodegradation, a mass transfer and degradation dynamic model of phenanthrene in Bio-PRBs will be established. The results could provide fundamental scientific basis and technical support for the remediation of PAHs in groundwater.

多环芳烃（PAHs）污染地下水是迫切需要解决的重要环境问题之一，其中原位渗透性反应墙联合微生物强化修复技术（生物PRB）由于经济、有效而被广泛采用。污染物在生物PRB修复过程主要受到生物降解、填充介质吸附以及在多孔介质中传质等多方面因素影响，因此，研究和掌握这些过程之间的相互作用，对保证修复效果的稳定性和持续性具有非常重要的实际意义。本课题拟以PAHs典型代表菲为研究对象，采用生物炭作为菲降解菌的固定化载体，探讨生物炭-降解菌的构效关系对菲吸附-降解协同作用机理；研究生物炭吸附-微生物降解多功能耦合PRB中微生物群落对环境因子的综合响应机制；阐明菲传质降解和微生物群落之间的相互关系，建立水力扩散、生物炭吸附和微生物降解多机制综合作用下菲在耦合PRB中的传质降解模型，为PAHs污染地下水的原位修复提供理论基础和技术支撑。

本项目针对多环芳烃和氯代烃污染地下水，富集驯化了多环芳烃和氯代烃降解菌群，研究了其对菲和四氯乙烯（PCE）污染地下水的微生物降解特性，解析了强化生物修复过程中微生物群落多样性的变化。研制了不同PRB高效填充材料空心莲子草生物炭和改性纳米零价铁（nZVI-LDH），阐明了其对菲和PCE的吸附/还原特性，建立了吸附/降解动力学模型，明确了填充材料耦合微生物体系对污染物的修复效果。构建了PRB柱体模拟反应装置并成功开展了模拟修复研究，采用MODFLOW-MT3D数值模拟建立了PRB修复运行过程中污染物迁移转化数学模型。通过分析实际污染场地PRB原位修复过程PRB上游、墙体以及下游污染地下水中微生物群落结构和组成，阐明了污染地下水微生物群落多样性指标与环境因子的关系，探索了微生物群落对环境因素的综合响应机制，为构建长效的原位PRB修复技术提供了一定的理论基础和技术支撑。