Soils’ Pollutions by Petroleum Products Accounting for Biodegradation and Concentration-Dependent Diffusivity

We have developed a model of the migration of hydrocarbon compounds in soils using diffusive formalism. Biodegradation of pollutant by microbial organisms have been considered. We have adopted a configuration of concentration-dependent diffusivity. The nonlinear diffusion equation governing the system was solved numerically using the DOPRI5 fourth-and-fifth-order Runge-Kutta variable step integrator. The highest depth attainable in the ground depends on the type of contaminant considered and on its initial concentration at the ground surface. We obtained that, the maximum depth reached by the contaminant increases with the increasing value of the initial concentration. This maximum depth also declined with increasing coefficient of biodegradation. The distribution profiles of the pollutant shown that the degree of penetrating of the pollutant increases with the time period. We have found a good agreement between the results derived here and those of Zygadlo and Gawdzyk. at low concentrations. While important discrepancies appear at high concentrations.