Membrane Biological Reactor (MBR) is a new type of wastewater treatment system which combines membrane separation technology with biological treatment technology. The membrane module is used to replace the secondary sedimentation tank at the end of traditional biological treatment technology to maintain high activated sludge concentration in the bioreactor and improve the organic load of biological treatment, so as to reduce the floor area of sewage treatment facilities and reduce the amount of excess sludge by maintaining low sludge load. Membrane separation equipment is mainly used to intercept activated sludge and macromolecular organic matter in water. The concentration of activated sludge (MLSS) in MBR system can be increased to 8000 ~ 10000mg / L or even higher, and the sludge age (SRT) can be extended to more than 30 days.