Sprocati Riccardo, Rolle Massimo
Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet Building 115, 2800 Kgs, Lyngby, Denmark.
Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet Building 115, 2800 Kgs, Lyngby, Denmark.
Water Res. 2022 Apr 15;213:118161. doi: 10.1016/j.watres.2022.118161. Epub 2022 Feb 3.
Electrokinetic techniques represent a valuable approach to enhance solute transport, reactant delivery and contaminant degradation in complex environmental matrices, such as contaminated soil and groundwater, and have a great potential for the remediation of many organic and inorganic pollutants. This study investigates the complex interplay between the key electrokinetic transport mechanisms, electromigration and electroosmosis, in physically heterogeneous porous media and its impact on tracer distribution, reactant mixing and degradation efficiency. We perform experiments in a multidimensional setup, considering different types of heterogeneities, injected tracers and reactants, as well as background electrolyte pore water with different chemical composition and pH. We show that EK transport is significantly affected by the physical heterogeneities, due to the interaction between electrokinetic and hydraulic processes, and by the pore water chemistry that plays a key role on the magnitude and spatial distribution of electroosmotic fluxes. The latter affect the overall transport of charged and non-charged species, including the migration velocity of injected plumes, their spatial patterns, spreading and mixing with the background groundwater, and the extent of degradation and the spatio-temporal evolution of reactive zones in the heterogeneous porous media. Process-based numerical modeling allowed us to interpret the experimental observations and to disentangle the coupled effects of physical, chemical and electrostatic processes in the multidimensional, heterogeneous setups. Besides elucidating the mechanisms controlling electrokinetic transport, the results of this study have also important implications for practical field implementation of EK approaches in intrinsically heterogeneous subsurface systems.
电动技术是一种在复杂环境基质（如受污染的土壤和地下水）中增强溶质传输、反应物输送和污染物降解的有效方法，在修复多种有机和无机污染物方面具有巨大潜力。本研究调查了物理非均质多孔介质中关键电动传输机制——电迁移和电渗之间的复杂相互作用及其对示踪剂分布、反应物混合和降解效率的影响。我们在多维实验装置中进行实验，考虑不同类型的非均质性、注入的示踪剂和反应物，以及具有不同化学成分和pH值的背景电解质孔隙水。我们表明，由于电动过程与水力过程之间的相互作用，EK传输受到物理非均质性的显著影响，并且孔隙水化学对电渗流的大小和空间分布起着关键作用。后者影响带电和不带电物质的整体传输，包括注入羽流的迁移速度、其空间模式、与背景地下水的扩散和混合，以及非均质多孔介质中降解程度和反应区的时空演变。基于过程的数值模拟使我们能够解释实验观测结果，并厘清多维非均质实验装置中物理、化学和静电过程的耦合效应。除了阐明控制电动传输的机制外，本研究结果对在本质非均质地下系统中实际现场实施EK方法也具有重要意义。
