Mathematical Modeling and Simulation of the Composting Process in a Pilot Reactor

Abstract

A mathematical model for the composting process with an engineering approach was presented. The model describes n-th order kinetics of the composting process (mesophilic–thermophilic phase) with mass and heat balances. Verification of the model was performed using experimental data obtained from a pilot reactor. Measured dynamic state variables used for verification were: organic matter mass, water mass in the mixture, amount of oxygen and carbon dioxide, temperature of mixture and temperature of gas phase. The model was implemented in MATLAB. Three kinetic parameters were estimated using the Marquardt method. Global sensitivity analysis and statistical F-test showed that the model is valid for predicting changes in five dynamic state variables. The advantage of the model is that it can be applied to composting processes with mixtures of different compositions in reactors with different volumes.