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）污染已经成为一个广泛和普遍的问题。 HOCs包括焦油、杂酚油、石油残留物和氯化溶剂，通常用于无数不同的行业。 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质。 因此，为了保护公众健康和环境，存在污染的场地迫切需要修复。 不幸的是，去除HOC污染已被证明是非常困难的。 这些化合物是非常持久的，由于其低的水溶性，其分布在地下是高度依赖于颗粒和宏观尺度的异质性。 尽管试图开发有效的HOC补救技术，但很少成功。 然而，用表面活性剂/助溶剂原位冲洗已被证明是有前途的。 将表面活性剂/助溶剂泵入表面下以通过降低界面张力来增加HOC解吸/增溶。 一旦在溶液中，污染物被移动到威尔斯井中，在那里溶液通常被泵出和处理。 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溶解的程度，以及溶液，污染物和土壤之间的相互作用的程度，因此，本研究的目的是表征HOCs在异质土壤环境中的分布，并开发和评估电动增强技术修复HOCs在困难的异质地下条件下。 虽然电动强化冲洗具有巨大的潜力，但其物理化学反应和传输机制复杂。 对这一过程的各个组成部分有一个完整的基本和概念性的理解是必不可少的。 为实现这一目标，将执行以下任务：（1）非均质土壤中HOC的表征，（2）用于增强HOC解吸和增溶的表面活性剂/共溶剂的评价，（3）从颗粒尺度非均质土壤中去除HOC的评估，（4）从宏观尺度非均质土壤中去除HOC的评估，及（5）发展修复受HOC污染土壤的设计指引。结合研究目标，该项目将为研究生和本科生的岩土工程和地质环境教育提供教育机会和基础设施改善程度. 研究设备，特别是物理二维仿真模型，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.