A Three-Phase Fluidized Bed Anaerobic Biofilm Reactor Model for Treating Complex Substrates

The main purpose of this paper is to present a model of a three-phase solid-liquid-gas system to investigate the hydrodynamic and biological behavior and performance of fluidized bed anaerobic biofilm reactors (FBABRs). A general one-dimensional axial dispersive dynamic model is proposed for computing the variation of the properties such as hold-ups and superficial velocities of all phases, biofilm thickness and biological and chemical specie concentrations. Biochemical transformations are assumed occurring only in the fluidized bed zone but not in the free-support material zone. The biofilm process model is coupled to the hydrodynamic model of the system through the biofilm detachment rate, which is assumed as a first-order function of the energy dissipation parameter. Non-active biomass is considered as particulate material subject to hydrolysis. A scheme of carbohydrate degradation, kinetic parameters accepted in the literature and design characteristics of a hypothetical FBABR are taken into account to show the model predictions. The performance of the FBABR is analyzed for different flow patterns through different dispersion coefficients for the phases.