Development of a Simplified Model for Completely Mixed Biofilm Reactor

A simplified model for the completely mixed biofilm process formulated correlations between entering and exiting substrate concentrations, average substrate flux in the biofilm and effective biofilm thickness. The model essentially considered the substrate mass transport into the biofilm as per Fick's second law and steady state substrate as well as biomass balance for biofilm. The numerical solution of the biofilm model involved evaluation of the average flux along with exiting substrate concentration and application of the Runge-Kutta method for determining the effective biofilm thickness. Accordingly, two computer programs were developed for the sake of quick solution. The solution model was successfully applied in several cases with varying range of representative input variables. The model performance was compared with available existing methods and validated with the experimental results. It was found as an easy, accurate and fast method that can be used for process design.