The research of applying multi-scale calculation to simulate concentration difference polarization appeared during MBR membrane separation process

The membrane module occupies only a small part in the membrane bioreactor(MBR), which results the contradiction on calculation scale between the micro-simulation on membrane separation process and the macro-simulation on MBR wastewater treatment process. This paper uses multi-scale calculation to solve the above contradiction. Solutions are as follows: use large-scale grids to simulate velocity field and concentration field in the MBR membrane pool macroscopically; while use fine grids to simulate each hollow fiber membrane in membrane modules, which can achieve the accurate simulation on concentration difference polarization under micro-scale. Two simulations with different scale are calculated respectively, and they obtain boundary conditions with each other by exchanging data. This paper not only achieves the macro-simulation on MBR wastewater treatment process, but also achieves the accurate simulation on concentration difference polarization appeared on the membrane surface. Finally, the factory's real data are substituted to the simulation module and use the software of Tecplot to visualize the experiment result. According to the simulation result on concentration difference polarization in this paper, the actual MBR system can be optimized, which can reduce the degree of membrane fouling effectively.