Study on Electrokinetic Soil Remediation Method

电动修复是一项新兴的技术，可用于原位去除非均质细粒土壤中的污染物。通过在被污染的土壤上施加一个低电平的直流电场来去除地下的污染物。污染物的迁移和去除机制主要是电势平流和离子迁移。然而，在这一过程中，同时发生了许多复杂的物理化学反应，这些反应可能会增强或减缓清除过程。然而，通过在不同土壤上进行的大量小试、大型实验室和中试现场试验，证明了该工艺的可行性。此外，还考虑了增强技术和混合过程，并对结果进行了描述。恒加V-…条件下高岭石的电动过程研究更长的时间，镉在阴极附近积累，但不会减少氢氧化物离子向土壤中的扩散。在保持阴极液pH为中性的情况下，镉向阴极迁移，而不会在阴极附近积累任何镉，并在阴极库中成功地被清除。还发现，通过监测局部电压和电流密度，可以在一定程度上掌握镉的电动处理过程。还考察了在中性pH区引入络合剂，通过离子迁移强化高岭石中镉的去除效果。选用的络合剂为乙二胺四乙酸(EDTA)。调查是在实验室规模的柱中进行的，其中包含被镉污染的高岭石。研究结果表明，镉向阳极迁移，没有镉的积累，并在阳极库中成功地被清除。同时，利用理论模型对电水力耦合梯度去除低渗透土壤中的污染物进行了研究，结果表明：与粘土/粉质土相比，电-水力耦合梯度能有效地去除导水率较高的土壤中的镉，但不能有效地去除粘土/粉质土中的镉。同时，在去除粘性/粉质土壤中的三氯乙烯时，可以有效地利用电-水力耦合梯度。麦克米伦数和电渗系数对镉的去除效率有影响，但在去除三氯乙烯时，麦克马林数的影响不大，而电渗系数的影响较大。较少

Electrokinetic remediation is an emerging technology that can be used to remove contaminants from heterogeneous fine-grained soils in situ. Contarninants in the subsurface are removed by the application of a low level direct current electric field across the contaminated soil. The primary contaminant transport and removal mechanisms are electrosmotic advection and ionic migration. However, there are many complex physicochemical reactions occurring simultaneously during the process that may enhance or retard the cleanup process. Nevertheless, the feasibility of the process has been demonstrated by results obtained from many bench scale and large scale laboratory and pilot scale field experiments performed on various soils.In the present study, major factors affection the removal process are examined. Also, enhancement techniques and hybrid process are considered and the results are described. In the study of elecrokinetic processing of kaolinite under the condition of constant applied v … More oltage, cadmium accumulation near the cathode without reducing the diffusion of hydroxide ion into the soil. In keeping the catholyte pH at neutrality, cadmium migrates toward the cathode without any accumulation of cadmium near the cathode and is successfully removed at the cathode reservoir. It was also found that the progress of electrokinetic processing of cadmium could be grasped to a certain extent by monitoring the local voltage and the current density. The effectiveness of introducing a complexing agent to enhance the removal of cadmium from kaolinite in the region of neutral pH by ionic migration is also examined. The complexing agent selected was ethylenediamineteraacetic acid(EDTA). The investigation was carried out in a laboratory-scale column containing kaolinite contaminated with cadmium. As the results of the study, cadmium migrates toward the anode without accumulation of cadmium and successfully removed at the anode reservoir. Also, in the study of the contaminant removal from Low permeability soils by coupled electric-hydraulic gradient using theoretical model, the following results are obtained: The coupled clcctric-hydraulic gradient can be effectively utilized to remove cadmium from soil with relatively high hydraulic conductivity compared with clayey/silty soils, but can not be effectively utilized in remove cadmium from clayey/silty soils. Meanwhile, in the removal of TCE from clayey/silty soils, the coupled electric-hydraulic gradient can be effectively utilized. Macmillan number and coefficient of clectroosmotic permeability affect the cleanup efficiency of cadmium Meanwhile, in the removal of TCE, the effect of Macmullin number is negligible, but the effect of coefficient of electrosmotic permeability is significant. Less