Simulation of competition between two microorganisms in a biofilm reactor based on different growth models

A simple biofilm model based on a model suggested by Soda et al. [S. Soda, E. Heinzle, M. Fujita, Modeling and simulation of competition between two microorganisms for a single inhibitory substrate in a biofilm reactor, Biotechnol. Bioeng. 66 (1999) 258-264] was used to simulate the competition between two microorganisms for space and a single inhibitory substrate in a biofilm reactor. Different growth kinetics were used to describe the growth of two microorganisms A and B which utilize the inhibitory substrate and the effect of biofilm thickness on microorganism concentration in biofilm was discussed. It was assumed that the biofilm has a uniform thickness and is composed of N segments (N = 4-10). The qualitative behavior of the biofilm reactor is characterized by four regions, I-IV, depending on the substrate concentration in feed, dilution rate, and growth kinetics. In region I, both microorganisms are washed out of the biofilm reactor. In region II, microorganism B is washed out of the biofilm and in region III microorganism A is washed out. In region IV both microorganism coexist with one another.