A MATHEMATICAL-MODEL FOR HOLLOW-FIBER BIOFILM REACTORS

In this work, a model is proposed to evaluate the performance and acti ve biofilm thickness of a hollow fiber biofilm reactor at different ce ll densities. The performance of the hollow fiber bioreactor was calcu lated for selected substrate lumen concentrations using cell density-d ependent effective diffusion coefficients and by introducing a mainten ance factor in the Monod kinetic expression, along with a concept of m inimum substrate concentration for active biofilm. This is a different approach to that normally used in the literature. The effectiveness f actors increased both with substrate and biofilm concentrations and th e effect of lumen concentration on the active biofilm thickness was mo re pronounced at lower biofilm densities. An increase in either lumen concentration or biofilm density caused increasingly pronounced decrea ses in the flux values at the fiber-biofilm interface. Owing to diffus ion limitations within the biofilm, the overall substrate consumption showed a parabolic profile for increasing biofilm density which has no t been reported before.