Effects of microarrangement of solid particles on PCE migration and its remediation in porous media

Abstract. Groundwater can be stored abundantly in granula-composed aquifers with high permeability. The microstructure of granular materials has important effect on the permeability of aquifers and the contaminant migration and remediation in aquifers is also influenced by the characteristics of porous media. In this study, two different microscale arrangements of sand particles are compared to reveal the effects of microstructure on the contaminant migration and remediation. With the help of fractal theory, the mathematical expressions of permeability and entry pressure are conducted to delineate granular materials with regular triangle arrangement (RTA) and square pitch arrangement (SPA) at microscale. Using a sequential Gaussian simulation (SGS) method, a synthetic heterogeneous site contaminated by perchloroethylene (PCE) is then used to investigate the migration and remediation affected by the two different microscale arrangements. PCE is released from an underground storage tank into the aquifer and the surfactant is used to clean up the subsurface contamination. Results suggest that RTA can not only cause more groundwater contamination, but also make remediation become more difficult. The PCE remediation efficiency of 60.01–99.78 % with a mean of 92.52 and 65.53–99.74 % with a mean of 95.83 % is achieved for 200 individual heterogeneous realizations based on the RTA and SPA, respectively, indicating that the cleanup of PCE in aquifer with SPA is significantly easier. This study leads to a new understanding of the microstructures of porous media and demonstrates how microscale arrangements control contaminant migration in aquifers, which is helpful to design successful remediation scheme for underground storage tank spill.

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Effects of Micro-Arrangement of Solid Particles on PCE Migration and Its Remediation in Porous Media

10.5194/hess-2017-493 ◽

2017 ◽

Author(s):

Ming Wu ◽

Jianfeng Wu ◽

Jichun Wu ◽

Bill X. Hu

Keyword(s):

Porous Media ◽

Granular Materials ◽

Storage Tank ◽

Sequential Gaussian Simulation ◽

Underground Storage ◽

Contaminant Migration ◽

Micro Structure ◽

Micro Scale ◽

Underground Storage Tank ◽

Regular Triangle

Abstract. Groundwater can be stored abundantly in granula-composed aquifers with high permeability. The micro-structure of granular materials has important effect on aquifer permeability; and the contaminant migration and remediation in aquifers is also influenced by the characteristics of porous media. In this study, two different microscale arrangements of sand particles are examined to reveal the effects of micro-structure on the contaminant migration and remediation. With the help of fractal theory, the mathematical expressions of permeability and entry pressure are conducted to delineate granular materials with regular triangle arrangement (RTA) and square pitch arrangement (SPA) at microscale. Using Sequential Gaussian Simulation (SGS) method, a synthetic heterogeneous site contaminated by Perchloroethylene (PCE) is then used to investigate the migration and remediation affected by the two different micro-scale arrangements. PCE is released from an underground storage tank into the aquifer and the surfactant is used to clean up the subsurface environment. Results suggest that RTA not only can cause larger range of groundwater contamination, but also can cause harder remediation for contaminated aquifer. The PCE remediation efficiency of 60.01 %–99.78 % with a mean of 92.52 % and 65.53 %–99.74 % with a mean of 95.83 % are achieved for 200 individual heterogeneous realizations based on the RTA and SPA, respectively, indicating that the cleanup of PCE in aquifer with SPA is significantly easier. This study leads to a new understanding of the microstructures of porous media and demonstrates how micro-scale arrangements control contaminant migration in aquifers, which is helpful to design successful remediation scheme for underground storage tank spill.

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A Multiphase Mixture Flow Model and Numerical Simulation for the Release of LPG Underground Storage Tank in Porous Environment

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2007-26415 ◽

2007 ◽

Cited By ~ 1

Author(s):

Ruihua Zhang ◽

Guohua Chen ◽

Si Huang

Keyword(s):

Porous Media ◽

Storage Tank ◽

Water Infiltration ◽

Viscous Force ◽

Underground Storage ◽

Liquid Region ◽

Flow State ◽

Liquefied Petroleum Gas ◽

Mixture Flow ◽

Underground Storage Tank

A physical process and mechanism of liquefied petroleum gas (LPG) flow dispersion in porous media for the releases at vapor and liquid region of Underground Storage Tank (UST) was analyzed. On the basis of the mixture model principle, a mathematical model was developed to simulate LPG flow dispersion in porous media. The gravity, capillary force, viscous force, interior resistance of porous media and gas-liquid interaction were incorporated into this model. And the non-Darcy coefficient of multiphase flow which is variable with Reynolds number was taken into account in the model, which was according with actual flow state. For LPG is insoluble in water, the formulation of LPG volumetric concentration was deduced, which simplifies computation process. The model was carried out to simulate a propane gas migration process in sand pond for UST release. From the simulation results, a detailed analysis was performed to investigate the effect of various influencing factors on infiltration flow: the direction of gas infiltration diffusion is influenced distinctly by gravity, release direction and the position of outlet in tank pond; the flow about release site and outlet is more active where the non-Darcy effect is obvious; the pressure drive is crucial for LPG infiltration; the gravity is a main factor to water infiltration; the saturation and viscous force of water can restrain the infiltration speed of propane. The model can lead to a good understanding of flow development and field effects of LPG in unsaturated porous media and can offer boundary conditions for modeling the subsequent fire explosion accidents.

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