The Soil as Bioreactor: Reaction-diffusion Processes and Biofilms

M. Richter[1], S. Moenickes[2], O. Richter[2], T. Schröder[1]
[1]BASF SE, Agricultural Center, Limburgerhof, Germany
[2]Institute of Geoecology, TU Braunschweig, Braunschweig, Germany

In a soil pore, water flows through the biofilm, where the density of the latter was assumed to represent a flow resistance. This mechanism was implemented as a local change of fluid viscosity proportional to local biofilm density. It was assumed that diffusive substrate transport is possible through the biofilm region such that the biofilm was able to degrade the substance. Maximum flow velocities decreased while biofilm was spreading.

The substrate concentration within the biofilm was very low because of degradation and smaller transport velocities. Where biofilm density was low, substrate could be adsorbed, respectively desorbed. The latter was bioavailable again and could be degraded.