Abstract
AbstractSolute transport through the clay liner is a significant process in many waste landfills or unmanaged landfills. At present, researchers mainly focus on the test study about semi-membrane property of clay material, however, the influence of chemical osmosis caused by membrane effect on solute transport and fluid velocity is insufficient. In this investigation, based on the classical advection-diffusion equation, a one-dimensional solute transport model for low-permeable clay material has been proposed, in which the coupled fluid velocity related with hydraulic gradient and concentration gradient is introduced, and the semi-membrane effect is embodied in the diffusion mechanism. The influence of chemical osmosis on fluid velocity and solute transport has been analyzed using COMSOL Multiphysics software. The simulated results show that chemical osmosis has a significant retarded action on fluid velocity and pollutant transport. The proposed model can effectively reveal the change in process of coupled fluid velocity under dual gradient and solute transport, which can provide a theoretical guidance for similar fluid movement in engineering.
Highlights
It is well known that clay materials can exhibit semipermeable membrane behavior, which has been proven by large amount of indoor and on-site experiments [1,2,3,4,5,6,7,8,9,10,11]Technical researchers typically pay more attention to the influence of clay membrane behavior on practical engineering, i.e. solid waste landfill, geothermal exploitation, nuclear waste disposal, intrusion of saltwater, and so on
Influence of Chemical Osmosis on Solute Transport and Fluid Velocity in Clay Soils 233 dynamic model of solute transport, considering the effect of membrane behavior and cation exchange, the results indicated that the chemiosmosis in geo-synthetic clay liner (GCL) could effectively delay the solute transport velocity
In order to study the influence of chemical osmosis on contaminant transport, the proposed convection-diffusion equation is solved by COMSOL Multiphysics software
Summary
It is well known that clay materials can exhibit semipermeable membrane behavior, which has been proven by large amount of indoor and on-site experiments [1,2,3,4,5,6,7,8,9,10,11]. Some researchers focussed on the influence of the osmotic efficiency coefficient on contaminant transport [17,18,19,20]. Their results indicated that chemical movement was hindered when ω value increased. The COMSOL Multiphysics software is used to conduct a numerical simulation to investigate the chemical osmosis on pore fluid flow and solute transport. Because the pore channels of clay are different in shape, the diffusion coefficient of contaminant is generally less than that in free water. Eq(10) is the convection-diffusion equation of 1D contaminant transport considering chemical osmosis effect under the combined action of a hydraulic gradient and concentration gradient
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