Electrokinetic Remediation of Heterogeneous and Low Permeability Soils Contaminated by Hydrophobic Organic Compounds

在整个美国，疏水性有机化合物(HOC)污染已经成为一个普遍而普遍的问题。HOC包括焦油、杂酚油、石油残渣和氯化溶剂，通常用于各种不同的行业。它们通常被归类为刺激物和/或毒素，许多已被确定为致命的致癌物。因此，为了保护公众健康和环境，现有污染场地迫切需要修复。不幸的是，消除临时污染已被证明是非常困难的。这些化合物由于其低的水溶解度而具有极高的持久性，并且它们在次表面内的分布高度依赖于颗粒和宏观尺度的非均质性。尽管人们试图开发有效的特别补救技术，但很少有成功的。然而，用表面活性剂/助溶剂进行原位冲洗已被证明是有前景的。表面活性剂/助溶剂被泵入地下，通过降低界面张力来增加HOC的解吸/增溶作用。一旦进入溶液，污染物就被动员到油井中，在那里通常将溶液抽出来并进行处理。然而，冲洗过程的有效性在很大程度上取决于污染物的解吸和增溶程度，以及溶液、污染物和土壤之间的相互作用程度。因此，本研究的目的是表征HOCs在非均质土壤环境中的分布，并开发和评估在困难的非均质地下条件下修复HOCs的电动强化技术。虽然电动强化冲洗具有很大的潜力，但其物理化学反应和传输机制是复杂的。对这一进程的各个组成部分有一个完整的、基本的和概念性的了解是至关重要的。为了实现这一目标，将完成以下任务：(1)非均质土壤中HOCs的表征，(2)用于增强HOC解吸和增溶的表面活性剂/助溶剂的评估，(3)从颗粒尺度非均质土壤中HOC去除的评估，(4)从宏观尺度非均质土壤中HOC去除的评估，以及(5)修复HOC污染土壤的设计指南的制定。结合研究目标，该项目将为研究生和本科生水平的岩土工程和地质环境教育提供教育机会和基础设施改进。研究设备，特别是物理二维模拟模型，将作为课堂教学的重要演示工具。

Throughout the United States, hydrophobic organic compound (HOC) contamination has become a widespread and pervasive problem. HOCs, which include tars, creosotes, petroleum residues, and chlorinated solvents, are commonly used in a myriad of different industries. They are generally classified as irritants and/or toxins, and many have been identified as lethal carcinogens. Therefore, in order to protect public health and the environment, sites with existing contamination urgently need remediation. Unfortunately, removing HOC contamination has proved to be very difficult. These compounds are extremely persistent due to their low aqueous solubilities, and their distribution within the subsurface is highly dependent on particle and macro-scale heterogeneities. In spite of attempts to develop efficient HOC remediation technologies, very few have been successful. In-situ flushing with surfactants/cosolvents, though, has been shown to be promising. Surfactants/cosolvents are pumped into the subsurface to increase HOC desorption/solubilization by lowering interfacial tension. Once in solution, the contaminants are mobilized towards wells where the solution is commonly pumped out and treated. The effectiveness of the flushing process, however, depends largely on the extent of contaminant desorption and solubilization, and the degree of interaction between the solution, contaminant, and soil.The objective of this research is therefore to characterize the distribution of HOCs in heterogeneous soil environments and develop and evaluate the electrokinetic enhancement technique for the remediation of HOCs under difficult heterogeneous subsurface conditions. Though electrokinetically enhanced flushing has great potential, the physicochemical reactions and transport mechanisms are complex. A complete fundamental and conceptual understanding of the various components of the process is essential. To achieve this goal, the following tasks will be performed: (1) characterization of the HOCs in heterogeneous soils, (2) evaluation of surfactants/cosolvents for enhanced HOC desorption and solubilization, (3) assessment of HOC removal from particle-scale heterogeneous soils, (4) assessment of HOC removal from macro-scale heterogeneous soils, and (5) development of design guidelines for remediating HOC-contaminated soils.In conjunction with the research objectives, the project will offer educational opportunities and infrastructure improvements for geotechnical and geoenvironmental education at both the graduate and undergraduate student levels. Equipment for the research, especially the physical two-dimensional simulation models, will serve as important demonstration tools for classroom instruction.