On the Drying Dynamics in Biofilters

F. Schönfeld
Hochschule RheinMain
University of Applied Sciences
Wiesbaden, Germany

The performance of biofilters relies on the presence of a sufficient amount of water in the biofilter material. And breakdown of filtration performance is often caused by inappropriate water content.

The present study focuses on the drying dynamics within such filter, which are modelled as wetted porous media. Analyzing gas flow and water content we find that such systems exhibit instable behaviour. Small variations in the initial conditions such as slight inhomogneities in moisture or porosity can be amplified during operation. The time constants for such coupled drying processes are analyzed within an 1-D modelling approach.

Furthermore, details of flow heterogeneity and drying are investigated by means of 2-D and 3-D models, which are solved by means of COMSOL Multiphysics.