Modeling biological air treatment processes

Biotechnologies for cleaning up gaseous emissions are becoming increasingly well-developed. They are classified as destructive technologies because they convert polluting organic compounds into carbon dioxide and water (see articles [G 1 700] and [G 2 971] ).

The operating characteristics of the different types of biological processes used to control the quality of gaseous emissions: biofilters, filter percolators and bioscrubbers, have been described at length in the article [G 1 780] "Bioprocesses in air treatment. Implementation". However, in order to better design, size and manage these units, it is necessary to account for all the physical, chemical and biological phenomena involved. Based on a detailed understanding of the processes involved, systems can be modeled to predict their purification performance under specified conditions.

This article describes the theoretical foundations on which the models classically developed in the literature are based, making it possible to represent the different types of bioreactors applied to the treatment of gaseous effluents.

These models are based on a deterministic approach coupled with a stochastic one, allowing the complexity of the mechanisms to be understood. They are based on the formulation and resolution of material balance equations, to which empirical relationships derived from statistical studies of experimental data are added. The basic principles of process engineering are applied, taking into account the specific features of biological systems.

Examples of applications of these models demonstrate their value in improving process performance and operational management. These examples also illustrate the gap between the simplicity of the representations adopted today and the complexity of the phenomena governing processes under real operating conditions, resulting in particular from their variability...