A theoretical and experimental analysis of membrane bioreactors behavior in unsteady-state conditions

Curcio, S.
Department of Chemical Engineering and Materials University of Calabria, Rende (CS), ITALY

The behavior of hollow fiber membrane bioreactors operating in recycle configuration is characterized from both theoretical and experimental point of view. The theoretical model is based on the unsteady-state balance equations governing momentum and mass transfer within the regions that can be identified in a hollow fiber reacting system with immobilized enzyme, coupled to the unsteady-state mass balance on the species in feed tank.

The resulting equation system has been solved by means of Finite Elements Method (FEM), implemented by FEMLAB 3.1 Chemical Engineering Module. The individuation of the most significant transport mechanisms affecting reactor performance has been carried out analyzing the dynamic evolution of three representative parameters, i.e. the effectiveness factor, the substrate conversion within the membrane and the bioreactor performance index, as functions of the operating conditions.

An experimental analysis of system behavior has validated the theoretical predictions. ß-galactosidase from Aspergillus oryzae has been immobilized, by physical adsorption, ultrafiltering through the membrane very diluted enzymatic solutions. Lactose and glucose concentrations, both in permeate and in feed tank, have been monitored thus showing a good agreement between experimental and theoretical results.