Effect of the microorganisms dynamics on the base subsidence of the solid household waste storage during consolidation

Abstract

The effect of the dynamics of the development of the microorganism biomass on the subsidence of the surface of the mass of the porous medium at the base of the storage of solid household waste was studied using mathematical and computer modeling methods. The repository of solid household waste is considered a source of the spread of organic pollutants that contribute to the development of the biomass of microorganisms. The subsidence model is considered from the theory of filtration consolidation of porous media. For this purpose, a corresponding boundary value problem in the domain with a free-moving boundary is formed. The classical equation of filtration consolidation is modified for the case of variable porosity due to biomass change. The finite element method allowed for solving the resulting mathematical model numerically in the form of a boundary value problem for the system of parabolic equations in the variable domain. Based on the developed algorithms, a software package for numerical experiments was created where the effect of microorganisms on the subsidence dynamics of a porous medium was investigated. Numerical experiments on a model example showed that the presence of microorganisms in soil pores slows the dissipation of excess pressure. However, this does not lead to a slowdown in subsidence but, on the contrary, to a particular increase of up to 18 % compared to the case of neglecting bioprocesses. From the point of view of the physics of the processes, this is explained by the increase in biomass, which leads to an increase in pressure, thus increasing the volume of filtered pore fluid and, hence, increasing subsidence.