Polymer solutions aid DNAPL (Dense Non Aqueous Phase Liquid)-contaminated soil remediation but are impacted by gravity and viscous forces. This study assesses the interplay between buoyancy and viscous forces in influencing the distribution of DNAPL and the invading phase, by introducing a densified brine (NaI) biopolymer (xanthan) solution as remediation fluid. A matrix of experiments was conducted, encompassing rheological measurements, multiphase flow tests in 1D-columns and 2D-tanks. Numerical modeling was used to assess polymer and DNAPL propagation under different conditions. NaI addition maintains xanthan's shear-thinning yet lowers mid-range shear viscosity 2.6 times. Confined column tests show similar 89% performance for viscous polymer solutions regardless of density. Unconfined tests mimicking real sites reveal non-densified viscous polymer solution yield mere 0.09 recovery due to density-driven flow. Densified polymer attains radial invasion, boosting recovery to 0.46 with 1.21 aspect ratio. Numerical simulations aligned with experiments, suggesting a near-zero gravity number is necessary to prevent density-driven flow problems. The multiphase flow experiments in confined multilayer system are performed and using the numerical modeling the effects of the permeability contrast and dimensions of the layers on the shape of front are analyzed.

中文翻译：

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使用致密生物聚合物盐水溶液对 DNAPL 污染的含水层进行重力驱动修复

聚合物溶液有助于修复 DNAPL（致密非水相液体）污染的土壤，但会受到重力和粘性力的影响。本研究通过引入致密盐水 (NaI) 生物聚合物（黄原胶）溶液作为修复液，评估了浮力和粘性力之间的相互作用对 DNAPL 分布和侵入相的影响。进行了一系列实验，包括流变测量、一维柱和二维罐中的多相流测试。数值模型用于评估不同条件下聚合物和 DNAPL 的传播。添加 NaI 可保持黄原胶的剪切稀化性，同时将中程剪切粘度降低 2.6 倍。密闭柱测试显示，无论密度如何，粘性聚合物溶液的性能均达到 89%。模拟真实地点的无侧限测试表明，由于密度驱动的流动，非致密化粘性聚合物溶液的回收率仅为 0.09。致密聚合物实现径向侵入，将回收率提高至 0.46，纵横比为 1.21。数值模拟与实验一致，表明接近零的重力数对于防止密度驱动的流动问题是必要的。进行了约束多层系统中的多相流实验，并利用数值模拟分析了渗透率对比和各层尺寸对前沿形状的影响。