微生物产电型渗透反应墙的构建及其对石油污染地下水的修复机制研究

Remediation for the groundwater contaminated by petroleum-hydrocarbons has elicited extensive concerns from petroleum environmental engineering fields in spite of complicated contaminants, high venture environment, great treated difficulty and high remediation cost. Here, microbial electricity permeable reactive barrier (ME-PRB) is designed according to the advantages arising from the cooperation between PRB and microbial fuel cell (MFC). As such, a new groundwater remediation system is formed, where porous medium adsorption, catalytic oxidation-reduction, microbial anaerobic and quasi aerobic degradation, and microbial anode electricity harmoniously function. In particularly, the influence of reactive barrier medium materials, petroleum-hydrocarbon contaminants characteristics, electrode materials and microbial character on degradation efficiency and electro-genesis performance of ME-PRB system has been investigated. The possible mechanism of microbial electro-genesis and degradation collaboration, microbial and medium materials cooperation and electron transfer in the groundwater multiphase conditions is studied and proposed. The investigation can favor for completion of theory foundation of ME-PRB remediation technology and especially provide valuable instructions for groundwater remediation of petroleum-hydrocarbon contaminants.

石油污染地下水具有生态风险强、治理难度大、修复成本高等特点，新型高效修复方法开发已成为研究热点。本项目基于微生物渗透反应墙（Permeable Reactive Barrier, PRB）与双室填料型微生物燃料电池（Microbial Fuel Cell , MFC）的优点与共性，构建具有类似双室填料MFC结构的微生物产能型PRB（Microbial Electricity PRB, ME-PRB）。形成一套复合多孔介质吸附、催化氧化还原、微生物厌氧降解、类好氧降解、微生物阳极产电等多种功能的石油污染地下水修复新体系。重点考察墙体介质材料、石油污染物特征、电极材料、微生物特征等因素对ME-PRB修复效果与产电性能的影响。同时开展微生物菌群协同产电与降解机制、微生物/介质材料协同作用机制、地下多相介质环境电子传递机制等研究，完善ME-PRB基础理论以指导石油烃及其衍生有机物污染地下水的修复。

石油污染地下水体的生态风险强、治理难度大、修复成本高，新型高效修复方法开发越来越重要。本项目基于微生物渗透反应墙（PRB）与填料型微生物燃料电池（MFC）的优点与共性，构建出具有填料型MFC结构的微生物产能型PRB（ME-PRB）。单室及双室ME-PRB均可利用石油污染水体为底物，但双室ME-PRB具有更优的产电及修复性能，输出电压高达268mV，石油类去除率在80%以上。墙体介质材料性质对ME-PRB性能及降解规律的影响极大，高吸附性活性炭介质促进微生物菌群衍生纳米导线，并形成网状结构促进电子传递及能量分配，使ME-PRB保持长期高效的产电性能，并使芳烃类及酚类污染物优先降解。阳极的外接电阻为2000Ω、电导率为7.64mS/cm、pH值为9、底物COD为400mg/L、磷酸盐缓冲液为200mmol/L；以及阴极为高浓度Fe(III)-EDTA溶液等工艺参数下，ME-PRB可以获得最优的修复与产电性能。在ME-PRB内，异常球菌促进类芽孢杆菌衍生纳米导线，降低电子传输阻碍；而微杆菌会拮抗异常球菌及类芽孢杆菌，抑制纳米导线衍生，阻碍电子有效传输。异常球菌不会抑制微杆菌代谢产生醋酸/棕榈酸，但微杆菌及类芽孢杆菌会抑制异常球菌代谢产生月桂酸，微杆菌及异常球菌会抑制类芽孢杆菌代谢分解醋酸。利用ME-PRB修复石油污染水体时，应考虑菌株间相互影响及污染物代谢特征，选用具有协同作用的类芽孢杆菌及异常球菌构建产电及降解菌群。