Theoretical Analysis of a Packed-bed Biological Reactor for Various Reaction Kinetics

The performance characteristics of a packed-bed biological reactor have been analysed taking into consideration the diffusional resistance of the biofilm. The model equations are solved by the method of orthogonal collocation from the transient to the steady state condition for various reaction kinetics of practical significance, namely Michaelis-Menten kinetics with and without substrate inhibition. The effect of various process variables of physical importance are investigated parametrically. It is found that the substrate conversion increases with increase in the Peclet number, the mass transfer coefficient, the surface area of biofilm and the film thickness. However, the substrate conversion is not affected by the film thickness after it has exceeded a certain value. Furthermore, analyses for individual kinetics corresponding to the three classic modes of non-competitive, competitive and anti-competitive inhibition have been presented. The results show that inhibitor concentration decreases the substrate conversion and that the extent of the effect is a maximum for the non- competitive case and a minimum for the anti-competitive case.