Use Computational Fluid Dynamics (CFD) to Optimize the Hydrodynamic in Large Scale Membrane Tanks

An integrated numerical approach, incorporating Eulerian multiphase model with porous medium scheme, was developed and implemented to study the hydrodynamic characteristics of large scale membrane bioreactor (MBR) systems. The numerical approach also successfully took into account the vertically dependent filtration flux and the effects of mixed liquor suspended solids (MLSS) concentration on mixed liquor viscosity.One example of optimization presented in this paper was for Cape Coral MBR plant. After optimization, the average mixed liquor and air velocities within membrane modules were improved by 44% and 22% respectively, and noticeable up-flow and down-flow circulations were achieved.The mixed liquor concentration within membrane modules was also calculated. Two scenarios of with mixed liquor pipes/jets and without mixed liquor pipes/jets were compared. The mixed liquor concentration in module 16 is about 20% higher than mixed liquor concentration in module 1, if mixed liquor distribution pipes/jets are removed.