Modelling of biofilm growth for photosynthetic biomass production in a pipe-overflow recirculation bioreactor

Abstract

A mathematical model was proposed to evaluate organic utilisation and biofilm thickness in a recently developed photo-bioreactor with pipe-overflow recirculation. The model was applied to describe organic uptake by biofilms under light starvation conditions and to determine biofilm growth during simultaneous occurrence of biofilm detachment in response to the development of shear force on the biofilm surface while mixed liquor trickled down the pipe. The proposed model, consisting of a one-dimensional bulk liquid model and a two-dimensional biofilm model, was used to describe purple non-sulfur bacteria (PNSB) activities in biofilms that developed on the pipes. The model was simulated at high recirculation to predict simultaneous substrate removal and biofilm growth. A good correlation was observed between the model prediction and experimental results for substrate removal and biofilm thickness for thin and fully active biofilms.