石油污染场地电动修复的干湿交替调控与污染物净化耦合机制

Wet/dry cycle is a kind of common phenomenon in contaminated site soil. Removal of pollutants was significantly influenced by the content of water. Electrokinetic remediation has been shown to be a promising method to remove organic pollutants in contaminated soils, as it offers a high degree of efficiency and time-effectiveness in soils with low permeability. However, the change of moisture, which is caused by the process of the natural flooding and drying, restricts its application for contaminated sites. In this study, petroleum contaminated soil is considered as the research object. Major research task is the coupling mechanism of drying-wetting cycles and pollution purifying during electrokinetic remediation of petroleum-contaminated soil. For this aim we will investigate the following contents: effect of different content of water on the removal of petroleum hydrocarbon during electrokinetic remediation, microbial ecology and petroleum hydrocarbon pollutants, migration, transformation and degradation by electrokinetic remediation in optimum moisture conditions, and the effect of electrokinetic remediation on removal of petroleum hydrocarbon based on condition of Soil drying-wetting cycles alternation. The aim of this project is to reveal changes of soil physical-chemical properties and microbial ecology, and the petroleum pollutants. The results are used to illustrate the effect of electrokinetic remediation with drying and wetting cycles controlling on migration, transformation and degradation of petroleum hydrocarbon. This will reveal coupling mechanism of drying-wetting cycles controlling and pollutant purification in petroleum contaminated site. It may enhance the effect and reduce energy consumption and provide scientific criterion for electrokinetic remediation of contaminated site soils.

污染场地存在干湿交替变化过程，不同水分条件影响土壤氧化还原电位、颗粒粒径及pH，最终影响污染物的净化。电动修复是去除土壤中有机污染物的有效手段，但自然淹水及落干过程所导致的场地水分差异制约了该技术的应用。本项目以石油污染场地为研究对象，对石油污染场地电动修复的干湿交替调控进行研究。具体内容包括，石油污染场地土壤不同含水条件的电动修复过程，最佳含水条件下电动修复对场地微生物生态、石油烃污染物迁移、转化及降解影响，石油污染场地电动修复的干湿调控机制与方法等三个方面。本项目旨在揭示污染场地电动修复的淹水-落干过程中土壤理化性质、微生物生态的变化，并由此导致的石油污染物变化规律，阐明电动修复的干湿交替调控下对石油烃的迁移、转化及降解作用，揭示干湿交替调控和污染物净化耦合机制，为提高石油污染场地修复效率及降低能耗提供科学判据。

电动修复技术在石油污染场地土壤修复方面已被证明具有一定应用前景。石油污染物的脱附和去除一定程度上受土壤水分条件制约。因此，研究电场条件下烃类污染物降解规律、土壤电动过程中微生物变化以及干湿调控措施等具有理论和工程实践意义。本课题开展了干湿交替对土壤性质的影响研究，探讨正常土壤含水条件的烃类降解修复机理，研究电动修复中不同含水土壤的增效调控方法，包括介于淹水和落水之间的泥浆化土壤电化学作用、高含水条件的表面活性剂的脱附作用等，这些将有助于将氧化和清洗与电动修复相结合提高石油烃的去除。结果表明，石油烃类有机物在土壤中去除主要是由电化学氧化和生物降解的叠加及协同作用。在二维对称电场中，电极附近TPH的降解率最高，而四电极对角线中心降解率最低。在高含水条件下，人工补充氧含量，可形成泥浆化土壤的电化学氧化；此外，在高含水的石油污染土壤中，脱附制剂的补充尤为重要，针对土壤中高岭土和蒙脱土的清洗药剂选择决定石油烃脱附的作用。综上，本研究对石油污染场地电动修复技术的应用具有重要作用。