EFFECTIVENESS FACTOR FOR A HOLLOW-FIBER BIOFILM REACTOR AT MAXIMUM SUBSTRATE CONSUMPTION

In this work, a model was proposed to evaluate the effectiveness facto r of a hollow-fiber biofilm reactor (HFBR) for optimum biofilm densiti es, to achieve a maximum substrate consumption rate. The effectiveness factor was calculated for selected lumen concentrations using a cell- density-dependent effective diffusion coefficient, Monod biokinetics a dapted for maintenance, and a minimum substrate concentration concept for biofilm activity in the model, a different approach from that in t he literature. The solution of the continuity equation revealed an opt imum biofilm density and active biofilm thickness, corresponding to a maximum substrate consumption rate within the biofilm. The optimum bio film density decreased with increasing lumen substrate concentrations, while the maximum substrate consumption rate and active biofilm thick ness parabolically increased, as experimentally observed in the litera ture. Meanwhile, an interesting descending trend of the effectiveness factor at optimum biofilm density was observed at low lumen substrate concentration and biofilm thickness values for different radial flow r ates.