PREDICTION OF AXIAL CONCENTRATION PROFILES IN AN EXTRACTIVE MEMBRANE BIOREACTOR AND EXPERIMENTAL-VERIFICATION

A steady-state mathematical model has been developed to predict axial- concentration profiles of a pollutant in an extractive-membrane biorea ctor (EMB). Typically, the previous models describe the pollutant conc entration profiles in the membrane-attached biofilms in a direction pe rpendicular to the membrane. In contrast, the model presented in this work describes not only the radial profiles, but also the axial profil es along the membrane length. Biofilms of Xanthobacter autotrophicus G J10 were grown on the surface of silicone rubber tubes. A diffusion-re action model was employed to describe the diffusion and reaction in th e biofilm in the radial direction. Membrane tubes were modelled as a s eries of mixed tanks to allow the prediction of axial concentrations. The model predictions were verified by experimental data from a range of operating conditions. These included different dissolved oxygen con centrations in biomedium and different wastewater flowrates. Finally, the rate-limiting step in the reactor was determined to be the mass-tr ansfer resistance of the pollutant in the biofilm.