A study of the migration characteristics of the Xanthan gum fluid in an aquifer and its effect on the migration of KMnO4
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摘要: 向地下水注入化学药剂进行修复时，药剂迁移主要集中在渗透性相对较高的区域，致使低渗透区内的污染物无法有效去除。通过注入聚合物（黄原胶）对地下水进行黏度控制，可以有效提高修复药剂在低渗透区的迁移能力，从而提高修复效果。黏性流体在地层中的迁移特性是该技术应用的理论基础，因此本研究运用一维模拟柱实验分析了含水层介质对黄原胶流体的阻滞作用，黄原胶注入前后介质的压力及渗透系数的变化以及黄原胶与修复药剂KMnO4迁移同步性。实验结果表明：当黄原胶溶液注入到介质后，介质对黄原胶的阻滞导致其有效孔隙度减小，因此会在一定程度上加速后续注入溶液溶质的运移，且介质渗透系数越小，对黄原胶阻滞作用越明显；黄原胶注入导致含水层渗透性降低，流体运移阻力增加，特别是在细砂和粉砂介质中，渗透系数都降低了一个数量级；虽然黄原胶和KMnO4在迁移锋面存在一定差异，但经过2 h后迁移速率基本相同，具有较好的同步性。Abstract: In the remediation injection of remedial amendment into groundwater, the amendment migration occurs mainly in the high permeability and hydraulically accessible zones, which results in the invalid contaminants removal in the low permeability zones. Using polymer (Xanthan gum fluid) to control the viscosity of groundwater can enhance the remedial amendments migration into low permeability zones, and improve the remediation efficiency. The migration of viscous fluid in the formation is the theoretical basis for the application of this technique. Therefore, in this study the sand-column one-dimensional simulations are used to analyze the characteristics of retention of the Xanthan gum fluid in the aquifer medium, the change in pressure and hydraulic conductivity before and after injection of Xanthan gum, and the synchronization migration of the Xanthan gum and KMnO4.The results indicate that when The Xanthan gum fluid was injected into the medium, the residual of The Xanthan gum led to the decrease in effective porosity, thus accelerating the solute transport in the subsequent solution to a certain extent. The greater the retention contributions are, the smaller the medium permeability conductivity is. The injection of the Xanthan gum fluid resulted in the decrease in the aquifer permeability, and increased the resistance of fluid migration. Especially, the hydraulic conductivity of fine sand and silt sand was reduced by an order of magnitude. There are some differences in the cover of migration of the KMnO4 and the Xanthan gum. After 2 h, the migration rate is basically the same with good synchronization.
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Key words:
- Xanthan gum fluid /
- migration /
- retention /
- hydraulic conductivity /
- potassium permanganate
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