Auxiliary analyses in support of performance assessment of a hypothetical low-level waste facility: Two-phase flow and contaminant transport in unsaturated soils with application to low-level radioactive waste disposal. Volume 2

Binning, Philip John; Celia, Michael A.; Johnson, Jeff

doi:10.2172/94557

Cited by 2 publications

(2 citation statements)

References 15 publications

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“…Spatially Distributed Model. The three-dimensional advection-dispersion equation for solute transport in an unsaturated porous medium, including the air-liquid phase partitioning, water infiltration and first-order degradation is given (19,20):…”

Section: Modeling Approachesmentioning

confidence: 99%

“…The three-dimensional advection-dispersion equation for solute transport in an unsaturated porous medium, including the air−liquid phase partitioning, water infiltration and first-order degradation is given , : ∂ ( θ w + K H θ a ) C w ∂ t − ∇ • ( θ w D w + K H θ a D a ) ∇ C w + q w ∂ C w ∂ z + θ w k C w = 0 where C w (M L −3 ) is the solute aqueous concentration, θ w and θ a (L 3 L −3 ) are respectively, the volumetric water and air contents; K H (-) is the dimensionless Henry’s constant; D w (L 2 T −1 ) is the dispersion tensor in water; D a (L 2 T −1 ) is the air diffusion coefficient; q w (L T −1 ) is the water infiltration rate constant and k (T −1 ) is the first-order degradation rate constant. A 3-D model domain is employed which contains spherical subdomain(s) representing beads embedded in the soil matrix.…”

Section: Modeling Approachesmentioning

confidence: 99%

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Evaluation of Bioaugmentation with Entrapped Degrading Cells as a Soil Remediation Technology

Owsianiak

Dechesne

Binning

et al. 2010

Environ. Sci. Technol.

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Soil augmentation with microbial degraders immobilized on carriers is evaluated as a potential remediation technology using a mathematical model that includes degradation within spatially distributed carriers and diffusion or advection-dispersion as contaminant mass transfer mechanisms. The total volume of carriers is a critical parameter affecting biodegradation performance. In the absence of advection, 320 and 20 000 days are required to mineralize 90% of the herbicide linuron by Variovorax sp. SRS16 encapsulated in 2 mm beads with 5 and 20 mm spacings, respectively. Given that many pesticide degraders have low intrinsic degradation rates and that only limited carrier to soil volume ratios are practically feasible, bioaugmented soils are characterized by low effective degradation rates and can be considered fully mixed. A simple exponential model is then sufficient to predict biodegradation as verified by comparisons with published experimental data. By contrast, the full spatially distributed model is needed to adequately model the degradation of faster degrading contaminants such as naphthalene and benzene which can be mass-transfer limited. Dimensionless Damköhler numbers are proposed to determine whether the spatially distributed model is required. Results show that field scale applications of immobilized degraders will be limited by the amount of carriers required to reach acceptable degradation rates.

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Section: Modeling Approachesmentioning

confidence: 99%

Section: Modeling Approachesmentioning

confidence: 99%

Evaluation of Bioaugmentation with Entrapped Degrading Cells as a Soil Remediation Technology

Owsianiak

Dechesne

Binning

et al. 2010

Environ. Sci. Technol.

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A Finite Volume Eulerian‐Lagrangian Localized Adjoint Method for Solution of the Contaminant Transport Equations in Two‐Dimensional Multiphase flow Systems

Binning¹,

Celia

1996

Water Resources Research

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An Eulerian‐Lagrangian localized adjoint method (ELLAM) numerical solution is developed for the multiphase contaminant transport equations in two dimensions. The ELLAM uses finite volume test functions in the space‐time domain defined by the characteristics of the hyperbolic part of the governing equation. The use of the characteristics results in an approximation that allows large time steps while still maintaining accurate solutions. This greatly reduces the computational effort required to find solutions to the advection‐dispersion equation. Combination of the finite volume test functions with the conservative form of the governing equation results in a local conservation of mass property. For problems with a constant saturation such as that of contaminant transport in the saturated zone this property is highly advantageous as the resulting numerical approximation conserves mass both globally and locally. For problems with a variable saturation the requirement of local conservation of mass is too stringent, particularly around first‐type boundaries where oscillations can occur because of errors inherent in the numerical determination of fluid velocities and in the backtracking routine. A combined conservative/nonconservative ELLAM is developed with an ELLAM formulation based on the nonconservative form of the governing equation being applied to subdomains intersecting first‐type boundaries and a conservative ELLAM being used for all other subdomains. The combined conservative/nonconservative ELLAM is compared to a Galerkin finite element scheme and is found to have greatly superior performance, requiring far fewer time steps to obtain a solution of equivalent accuracy.

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Auxiliary analyses in support of performance assessment of a hypothetical low-level waste facility: Two-phase flow and contaminant transport in unsaturated soils with application to low-level radioactive waste disposal. Volume 2

Cited by 2 publications

References 15 publications

Evaluation of Bioaugmentation with Entrapped Degrading Cells as a Soil Remediation Technology

Evaluation of Bioaugmentation with Entrapped Degrading Cells as a Soil Remediation Technology

A Finite Volume Eulerian‐Lagrangian Localized Adjoint Method for Solution of the Contaminant Transport Equations in Two‐Dimensional Multiphase flow Systems

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