Mathematical Description of the Initial Stages of a Composting Process in a Batch Bioreactor Article uri icon


  • A mathematical model to describe a composting process in a tubular bioreactor is proposed in this work. This model considers the bioreactor as a biphasic system in which the gas phase provides the oxygen, whereas in the solid-liquid phase, the microorganisms grow by consuming the substrate and dissolved oxygen. The mathematical model describes temperature and oxygen and water concentration changes in both phases, as well as microorganisms, substrates, and Salmonella concentrations in the solid-liquid phase as a function of time and position in the bioreactor. The composting model proposed was sensitive to changes in the maximum growth rate, substrate to biomass yield, ambient temperature, and initial concentration of water in the solid-liquid phase. A design analysis of the bioreactor was performed, keeping the total bioreactor volume constant. The study consisted of changing (i) the interstitial gas velocity, (ii) the initial mass fraction of water in the solid-liquid phase, and (iii) the global heat transfer coefficient. It was found that an increase in the bioreactor insulation was the most proper alternative to achieve an adequate sanitization of the composting system followed by the initial water concentration in the solid-liquid phase. Overall, the mathematical model could be used to design nonexistent composting tubular bioreactors or describe existent bioreactors to help achieving sanitizing conditions. © 2022 American Chemical Society.

publication date

  • 2022-01-01