Application of Computational Fluid Dynamics to Optimisation of Membrane Module Configurations in Submerged Membrane Bioreactors

A three-dimensional Computational Fluid Dynamics model, coupled with sludge rheology models to account for the behaviour of mixed liquor and porous media models to represent the resistance of membranes to the fluid field, was developed and used in estimating shear stress in the filtration zone of membrane bioreactors. The influence of a suite of factors on shear stress including aerator position, nozzle direction, bubble size, membrane orientation, packing density and the geometry of the filtration chamber was examined using the CFD model. The highest shear stress was predicted to occur for vertically oriented membranes aligned in parallel with air diffuser nozzles generating 10 mm diameter bubbles constrained to travel in the filtration zone by solid baffles encasing the membrane unit.