Dynamic in-series resistance modeling and analysis of a submerged membrane bioreactor using a novel filtration mode

This study is focused on the physical filtration characteristics of a flatsheet membrane bioreactor (MBR) operated under a novel filtration mode. The objective of this research was to demonstrate the possibility of running an MBR with high MLSS concentration for prolonged periods without frequent blocking of the membranes. Current MBR designs, mostly dictated by the manufacturers, have restrictions on the level of MLSS due to fouling. It has been observed that this restraint can be eliminated by applying high shear rates for better removal of cake layer from membrane surface. A pilot scale MBR was setup at the inlet works of a domestic sewage treatment plant. The system was dynamically modeled and calibrated for flux, hydraulic permeability, transmembrane pressure using the in-series resistance model. Resistance components were experimentally determined and compared against the results of dynamic simulations. Intrinsic membrane resistance (Rm) and fouling resistance (Rf) were the major components contributing to total resistance with fractions of 69% (Rm/Rt) and 30% (Rf/Rt) respectively. It was found that cake resistance did not have major impact on the total resistance which was linked to the high aeration intensity. Proposed model was validated by experiments which indicated its potential use on other MBR systems.

► In-series resistance model dynamically calibrated to match the experimental data.
► High aeration intensities resulted in low cake resistance throughout the study.
► High shear stress changed the longterm filtration and fouling characteristics.
► MBR plant was operable with less relaxation periods under high aeration intensity.
► Novel filtration mode enabled longterm operation at high MLSS with low viscosity.