Modeling of multifield coupling interactions in an aerobic landfill based on the finite volume method

Abstract

Aeration, which creates an aerobic environment by air injection, has been proven to be an effective method to accelerate waste stabilization and reduce pollution load in landfills. To reveal the multi-field coupling interactions in an aerobic landfill, this study developed a three-dimensional multifield coupled model involving anaerobic–aerobic biodegradation, gas–liquid flow, methane oxidation, water evaporation, multicomponent gas diffusion (CO2, CH4, O2, N2 and H2O) and heat transfer. The model with spaced aeration wells and recovery wells is solved by OpenFOAM based on the finite volume method. The results show that a certain amount of oxygen is distributed around the aeration well, while the methane volume fraction decreases to approximately zero in most regions except around the recovery well. In the aerobic reaction area, the temperature increased up to 60 ℃, accelerated water evaporation and inhibited the reaction. The maximum vapor volume fraction occurs at the aerobic front due to the injection of dry air at the aeration well and liquefaction outside the aerobic zone. To achieve high-efficiency aerobic remediation, aeration well screens should be buried at a depth of 43% of waste thickness (from the longitudinal midpoint of the well) with a length accounting for 40–53% of waste thickness.