Bioreactor (MBR) is a new wastewater treatment system which combines membrane separation technology and biological treatment technology. The membrane module is used to replace the terminal secondary sedimentation tank of the traditional biological treatment technology, so as to maintain the high activated sludge concentration in the bioreactor and increase the organic load of biological treatment, thereby reducing the occupied area of sewage treatment facilities, and reducing the excess sludge by keeping the sludge load low. Membrane separation equipment is mainly used to intercept activated sludge and macromolecular organic matter in water. The concentration of activated sludge (MLSS) in membrane bioreactor system can be increased to 8000 ~ 10000 mg/L or even higher. Sludge age (SRT) can be extended to more than 30 days.

Because of its effective interception, membrane bioreactor can intercept microorganisms with long generation cycle and realize deep purification of sewage. At the same time, nitrifying bacteria can fully propagate in the system, and its nitrification effect is obvious, which provides the possibility for deep phosphorus and nitrogen removal.