Denitrification in a Homogeneous, Closed System

A simulation model describing microbial respiration and denitrification was developed for a homogeneous (i.e., spatially uniform in all phases) soil layer, in which no transport processes occurred. Major processes included were growth and maintenance of biomass at the expense of glucose carbon and the concomitant reduction of nitrate to molecular nitrogen, via the intermediates nitrite and nitrous oxide. Growth of biomass was calculated by a first-order rate equation in which the relative growth rate was described by a double Monod equation consisting of rate-limiting factors for carbon and nitrogenous substrates. The Pirt equation was used to calculate the consumption rates of substrates. As a starting point to parameterize the model, we compiled a data set from various literature sources and investigated the possibility of simulating experimental observations of the sequence of denitrification products by modifying some of these literature data within reasonable limits. We concluded that the model gives a reasonable description of the denitrification process, because the experiments reported in this paper and one from the literature could be simulated rather well. The objective of this paper is to describe the model with the underlying assumptions and to compare some of its results with experimental data.