电场强化高分子量多环芳烃污染土壤修复机理及过程调控

High molecular weight polycyclic aromatic hydrocarbons (HMW PAHs) are a class of persistent organic pollutants ubiquitously occurring in soil, which have complex structure and high hydrophobicity. Electrokinetic-enhanced remediation is an effective technology to remove HMW PAHs from soil. But, it is difficult to achieve synergistic effect of electric and microbial degradation during remediation. In the project, temporal and spatial variation of benzo(a)pyrene, microorganism and soil properties will be analysed using chemical analysis and molecular biotechnology in simulation experiments of electrokinetic-enhanced remediation of soil contaminated with benzo(a)pyrene. The relationship between electric and microbial degradation will be elucidated according to the above analysis, and the mechanism of electrokinetic-enhanced remediation of soil contaminated with HMW PAHs will be clarify on the basis of the relationship benzo(a)pyrene and microorganism in the same sampling and under the same voltage. At the same time, the controlling methods of enhancing the synergistic effect of electric and microbial degradation will be put forward based on the critical factors affecting the structure and function of microbial community.These studies will not only offer theoretical support for increasing the efficiency for electrokinetic remediation of soil contaminated with HMW PAHs, they will also provide references and scientific basis for the research of electrokinetic remediation of soil contaminated other persistent organic pollutants .

高分子量PAHs结构复杂，疏水性强，是土壤中广泛存在的难降解有机污染物。电场强化修复技术是一种有效去除土壤中高分子量PAHs的途径，实现电场直接降解作用和微生物降解作用的协同是该技术难点。本项目以高分子量PAHs苯并[a]芘污染土壤为修复对象，通过室内模拟实验，采用化学分析和分子生物学方法研究不同电场强度下土壤中苯并[a]芘、微生物和土壤理化性质的空间和时间变化规律，依据电场、苯并[a]芘、微生物和土壤理化性质之间的对应关系，探明电场直接降解和微生物降解之间关系及影响两者协同作用的因素，阐明电场强化高分子量PAHs污染土壤修复机理，建立促进电场强化降解的调控方法，实现电场强化过程中电场和微生物作用的协同，提高高分子量PAHs污染土壤修复效率。该研究成果不仅可为高分子量PAHs污染土壤修复效率的提高提供详实理论基础，同时也可为开展其它持久性有机污染土壤电场强化修复研究提供借鉴方法和科学依据。

实现电场直接降解和微生物降解作用协同是电场强化高分子量PAHs污染土壤修复技术难点。本项目以高分子量PAHs苯并[a]芘污染土壤为修复对象，系统分析了修复过程中苯并[a]芘、微生物和土壤理化性质的空间和时间变化。通过研究发现：（1）电场强化修复高分子量PAHs污染土壤包括电化学氧化和微生物降解作用，电化学氧化主要发生在阳极端，微生物降解作用主要发生在中间及阴极端；（2）电化学氧化作用与电场强度存在正相关，而微生物降解作用在一定电场范围内与电场存在正相关关系，但超过一定的电场强度，微生物的降解作用会减弱；（3）在适宜电场条件下电化学氧化和微生物降解作用存在协同效应，叠加电场可实现两者高效协同，而且通过对土壤中营养、水分、pH、施加微生物的优化调控，可有效增强电场条件下微生物的降解功能。该研究成果可为持久性有机污染土壤修复提供理论依据和借鉴。