Robert Thomas, Martel Richard, Conrad Stephen H, Lefebvre René, Gabriel Uta
Institut National de la Recherche Scientifique, INRS-Eau, Terre et Environnement, Québec, Canada.
J Contam Hydrol. 2006 Jun 30;86(1-2):3-31. doi: 10.1016/j.jconhyd.2006.02.013. Epub 2006 Apr 19.
This research focused on the optimization of TCE dissolution in a physical two-dimensional model providing a realistic representation of a heterogeneous granular aquifer. TCE was infiltrated in the sand pack where it resided both in pools and in zones of residual saturation. Surfactant was initially injected at low concentration to minimize TCE remobilization at first contact but was incrementally increased later during the experiment. Xanthan gum was added to the injected surfactant solution to optimize the sweep efficiency through the heterogeneous medium. Photographs and digital image analysis illustrated the interactions between TCE and the injected fluids. During the polymer flood, the effects of heterogeneities inside the sand pack were greatly reduced by the increased fluid viscosity and the shear-thinning effects of the polymer. The polymer also improved the contact between the TCE ganglia and the surfactant-polymer solution, thereby promoting dissolution. Surfactants interacted with the polymer reducing the overall viscosity of the solution. At first contact with a 0.5%(mass) surfactant solution, the TCE pools drained and some remobilization occurred. However, no TCE bank was formed and TCE did not penetrate into any previously uncontaminated areas. As a result, TCE surface area was increased. Subsequent surfactant floods at higher surfactant concentrations did not trigger more remobilization. TCE was mainly dissolved by the solution with the highest surfactant concentration. Plugging from bacterial growth or microgel formation associated to the polymer at the inflow screen prevented the full completion of the experiment. However, more than 90% of TCE was recovered with the circulation of less than 6 pore volumes of surfactant-polymer solution.
本研究聚焦于在一个物理二维模型中优化三氯乙烯（TCE）的溶解，该模型逼真地呈现了非均质粒状含水层。TCE被注入砂柱中，它既存在于水洼中，也存在于残余饱和度区域。表面活性剂最初以低浓度注入，以在初次接触时尽量减少TCE的再迁移，但在实验后期逐渐增加浓度。黄原胶被添加到注入的表面活性剂溶液中，以优化通过非均质介质的波及效率。照片和数字图像分析展示了TCE与注入流体之间的相互作用。在聚合物驱过程中，砂柱内部非均质性的影响因流体粘度增加和聚合物的剪切变稀效应而大大降低。聚合物还改善了TCE液滴与表面活性剂 - 聚合物溶液之间的接触，从而促进溶解。表面活性剂与聚合物相互作用，降低了溶液的总体粘度。在与0.5%（质量）的表面活性剂溶液初次接触时，TCE水洼排空，发生了一些再迁移。然而，没有形成TCE堤岸，TCE也没有渗透到任何先前未受污染的区域。结果，TCE的表面积增加了。随后在更高表面活性剂浓度下的表面活性剂驱没有引发更多的再迁移。TCE主要被具有最高表面活性剂浓度的溶液溶解。在进水筛管处，细菌生长或与聚合物相关的微凝胶形成导致的堵塞妨碍了实验的完整完成。然而，在循环不到6孔隙体积的表面活性剂 - 聚合物溶液的情况下，回收了超过90%的TCE。
