A hybrid equilibrium model of solute transport in porous media in the presence of colloids

Jiang, Shiyan; Çorapçıoğlu, M. Yavuz

doi:10.1016/0927-7757(93)80021-6

Cited by 26 publications

(14 citation statements)

References 25 publications

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“…Our colloid-facilitated transport model closely follows development of many similar models (e.g., Corapcioglu and Jiang, 1993;Jiang and Corapcioglu, 1993;Saiers and Hornberger, 1996;van de Weerd and Leijnse, 1997;Bekhit and Hassan, 2005). Major differences in our model include consideration of water contents, water fluxes, and air-water interfacial areas that may change in time and space (i.e., transient variably-saturated water flow), the presence of colloids on the air-water interface, and adjustment of all kinetic rates to the number of colloids present in the system.…”

Section: Colloid-facilitated Solute Transportmentioning

confidence: 99%

Colloid‐Facilitated Solute Transport in Variably Saturated Porous Media: Numerical Model and Experimental Verification

Šimůnek

Pang

et al. 2006

Vadose Zone Journal

155

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Strongly sorbing chemicals (e.g., heavy metals, radionuclides, pharmaceuticals, and explosives) in porous media are associated predominantly with the solid phase, which is commonly assumed to be stationary. However, recent field‐ and laboratory‐scale observations have shown that in the presence of mobile colloidal particles (e.g., microbes, humic substances, clays, and metal oxides), colloids can act as pollutant carriers and thus provide a rapid transport pathway for strongly sorbing contaminants. To address this problem, we developed a one‐dimensional numerical model based on the HYDRUS‐1D software package that incorporates mechanisms associated with colloid and colloid‐facilitated solute transport in variably saturated porous media. The model accounts for transient variably saturated water flow, and for both colloid and solute movement due to advection, diffusion, and dispersion, as well as for solute movement facilitated by colloid transport. The colloid transport module additionally considers the processes of attachment/detachment to/from the solid phase and/or the air–water interface, straining, and/or size exclusion. Various blocking and depth dependent functions can be used to modify the attachment and straining coefficients. The solute transport module uses the concept of two‐site sorption to describe nonequilibrium adsorption–desorption reactions to the solid phase. The module further assumes that contaminants can be sorbed onto surfaces of both deposited and mobile colloids, fully accounting for the dynamics of colloid movement between different phases. Application of the model is demonstrated using selected experimental data from published saturated column experiments, conducted to investigate the transport of Cd in the presence of Bacillus subtilis spores in alluvial gravel aquifer media. Numerical results simulating bacteria transport, as well as the bacteria‐facilitated Cd transport, are compared with experimental results. A sensitivity analysis of the model to various parameters is also presented.

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Section: Colloid-facilitated Solute Transportmentioning

confidence: 99%

Colloid‐Facilitated Solute Transport in Variably Saturated Porous Media: Numerical Model and Experimental Verification

Šimůnek

Pang

et al. 2006

Vadose Zone Journal

155

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“…Pq•H Thus locally at (x, t) there is no reduction in sorption of C nf = C• to soil, and there is no sorption of C•, to soil, as Cm, = 0. This discussion also holds true if the effective isotherm has the form of (35) in part i related to the modeling assumption of Jiang and Corapcioglu [1993], and the sorption of the carrier is in equilibrium, that is, So = •o (Co). For Co (x, t) --> o• (for fixed (x, t)), we find (part 1, equation (10))…”

Section: *[X T C(x T)] --> P*•f *•F[c(x T)] (6)mentioning

confidence: 66%

“…new terms on the right-hand side, the first is only present for space-dependent 02/0•. Together they can be interpreted as an additional transport term owing to convective transport acting on the carrier-bound HOC mass concentrapore-space reduction due to the sorption of carrier to the soil, as it has also been proposed byCorapcioglu and Jiang [ 1993] andJiang and Corapcioglu [ 1993], leads to the following modifications: In(3)and (4) of part 1, 0 has to be substituted by 0 -[p,•oSo + P,vo •o (Co)]/po, where Po [M L-3] is the density of the carrier DOC. As this may be interpreted as a new, diminished, and (x, !…”

mentioning

confidence: 99%

The modeling of reactive solute transport with sorption to mobile and immobile sorbents: 2. Model discussion and numerical simulation

Totsche¹,

Knabner²,

Kögel‐Knabner³

1996

Water Resources Research

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We analyze mathematically and numerically a model derived in part 1 of this paper [Knabner et al., this issue]. The model deals with carrier‐influenced transport and besides advective and dispersive transport and equilibrium and nonequilibrium sorption takes into account both carrier facilitation and cosorption. Guidelines are derived, whether the overall mobility is enhanced or reduced and various other properties of the model elucidated, in particular for varying carrier concentrations. We indicate how to modify existing numerical codes for the usual adsorption model and discuss simulations for experimental data sets.

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“…We will discuss the conse-REACTIVE SOLUTE TRANSPORT, 1 quence for the general model in the section "Extensions," in part 2. The model developed by Corapcioglu and Jiang [1993] and Jiang and Corapcioglu [1993] is similar to our model but has various differences. We concentrate on the latter paper, since as an essential difference the first paper considers a kinetic description of the formation of carrier-bound HOC by a linear first-order rate function, that is, instead of (9).…”

Section: Linear Sorption Of Hoc Tomentioning

confidence: 99%

The modeling of reactive solute transport with sorption to mobile and immobile sorbents: 1. Experimental evidence and model development

Knabner¹,

Totsche²,

Kögel‐Knabner³

1996

Water Resources Research

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Modeling carrier‐influenced transport needs to take into account the reactivity of the carrier itself. This paper presents a mathematical model of reactive solute transport with sorption to mobile and immobile sorbents. The mobile sorbent is also considered to be reactive. To justify the assumptions and generality of our modeling approach, experimental findings are reviewed and analyzed. A transformation of the model in terms of total concentrations of solute and mobile sorbents is presented which simplifies the mathematical formulations. Breakthrough data on dissolved organic carbon are presented to exemplify the need to take into account the reactivity of the mobile sorbent. Data on hexachlorobiphenyl and cadmium are presented to demonstrate carrier‐introduced increased mobility, whereas data on anthracene and pyrene are presented to demonstrate carrier‐introduced reduced mobility. The experimental conditions leading to the different findings are pointed out. The sorption processes considered in the model are both equilibrium and nonequilibrium processes, allowing for different sorption sites and nonlinear isotherms and rate functions. Effective isotherms, which describe the sorption to the immobile sorbent in the presence of a mobile sorbent and rate functions, are introduced and their properties are discussed.

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A hybrid equilibrium model of solute transport in porous media in the presence of colloids

Cited by 26 publications

References 25 publications

Colloid‐Facilitated Solute Transport in Variably Saturated Porous Media: Numerical Model and Experimental Verification

Colloid‐Facilitated Solute Transport in Variably Saturated Porous Media: Numerical Model and Experimental Verification

The modeling of reactive solute transport with sorption to mobile and immobile sorbents: 2. Model discussion and numerical simulation

The modeling of reactive solute transport with sorption to mobile and immobile sorbents: 1. Experimental evidence and model development

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