Abstract
This paper presented the first part of the studies about the development of a tool for groundwater contamination prediction, conducted by the Laboratory of Sciences and Technology of Water (UAC/Benin). The investigation made consisted in estimating the combined effect of retardation factor and biodegradation on migration processes of leachate, in the underlying soils of household waste dumpsites, without active safety barrier. Leachate infiltration tests for different initial conditions were made on soil columns and the breakthrough curves were traced for electrical conductivity, the 5 day biochemical oxygen demand (BOD5) and total kjeldahl nitrogen TKN. A mathematical migration model was developed and solved numerically by finite difference method and implemented with Matlab R2013a. Thus, the calibration of the model was made with electric conductivity data by determining the dispersion coefficient of the studied soils (D = 0.96 cm2/min). Simulations for model verification showed that the established model can perfectly predict the migration of biodegradable organic pollution (BOD5) but did not give conclusive results for the monitoring of nitrogenous organic matter (TKN). The influence of the retardation factor on the migration of biodegradable organic pollutants in soils was linear, while the biodegradation rate of the organic material on migration showed an exponential pattern.
Highlights
The migration of solutes in a porous medium is usually controlled by three mechanisms: Convection, molecular diffusion and mechanical dispersion [1] [2]
Leachate infiltration tests for different initial conditions were made on soil columns and the breakthrough curves were traced for electrical conductivity, the 5 day biochemical oxygen demand (BOD5) and total kjeldahl nitrogen TKN
To effectively prevent contamination of groundwater by leachate, it is important to define models which can combine the mechanisms of the fluid flow and transport in soils to the mechanisms related to the pollutants nature
Summary
The migration of solutes in a porous medium is usually controlled by three mechanisms: Convection, molecular diffusion and mechanical dispersion [1] [2]. It is well known that the dispersion of a pollutant in a soil, saturated or not, is influenced both by the intrinsic properties of the soil (such as its nature, porosity, tortuosity and grain size distribution), and by the properties of the fluid flow and transportation (such as viscosity, density and velocity of the fluid) [4] [5]. The change in concentration of a passive pollutant A between two points of a soil column is considered as a one-dimensional transport problem, which is simultaneously subjected to the phenomena of convection and dispersion [15] [16] This gives: ∂cA = ∂t Dz ∂2cA ∂z 2 − qz ∂cA ∂z + S (cA ) (2.1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
