Biological Driven Phase Transitions in Fully or Partly Saturated Porous Media: A Multi-Component FEM Simulation Based on the Theory of Porous Media

Abstract

AbstractBacterial methane oxidation in landfill cover soils, which turns the emitting methane caused by waste degradation into carbon dioxide, reduces the climate impact of landfill gas emissions significantly, since methane is estimated to have a global warming potential (GWP) of 25 over 100 years (GWP of CO2 = 1). To understand and forecast the biological processes, a Finite-Element Model (FEM) is developed to simulate the behavior of methanotrophic layers. A multiphasic continuum mechanical approach based on the extended Theory of Porous Media (eTPM) is chosen, providing a macroscopic, multi-component view on the bacterial progress including the relevant gas transport processes of diffusion and advection in porous media as well as bacterial driven conversion processes. The presented thermodynamically consistent model also considers energy production within the gas phase resulting from exothermic reactions. An experimental setup was developed to validate the model also in terms of temperature development via the thermal imaging technique.KeywordsBacterial methane oxidationExtended Theory of Porous Media (eTPM)Mixture theoryMulti-Component approachMultiphysicsThermodynamicsModel couplingFinite-Element Method