Numerical optimization of membrane module design and operation for a full-scale submerged MBR by computational fluid dynamics

The hydrodynamics in the membrane module of a full-scale sMBR at 500 m3/d was simulated by computational fluid dynamics (CFD) in this study. Several key indexes, including membrane distance (d), aeration design, height of gas-liquid dispersion hm, and freeboard height hf and operational conditions, including SADp and liquid viscosity, were optimized through investigating their impacts on water velocity distribution and membrane shear stress. The CFD model was validated by comparing the simulated trace element RTD curves with experimental results. The optimal design and operational parameters for the full scale sMBR are as following: membrane distance d = 35 mm, air diffusers parallel located 75–100 mm under the bottom of the membrane module, the free board height hf adjusted to 400 mm, and the SADp recommended as 20 in the full-scale MBR studied.