Optimization of a model for denitrification with batch and porous media experiments

Abstract

Denitrification, the microbial process (and its subprocesses) of reducing nitrogenous oxides to gaseous nitrogen, is usually modelled using the relevant scale, i.e. microscopic, laboratory, field, or landscape scale. It is shown that a newly developed model can simulate several experiments with a denitrifying strain of bacteria at the microscopic scale with different initial oxygen and nitrate concentrations all at once. It is shown that for this, a new approach for the onset of denitrification is needed. It will then be investigated whether the model can be transferred from the microscopic scale to the laboratory scale to simulate an experimental setup with sintered glass beads that mimic hot spots in the soil. For this, the reaction from the batch experiment model is not changed, but diffusion of the components is added. While the spatially resolved model seems to incorporate the spatial structure correctly, shown by the good agreement between simulation and experiment under purely oxic conditions, there is a structural mismatch between the simulation and the experiments with denitrification.