The English name of immersed ultrafiltration is: Flow Split, Flow Split SMF (Patent No.: ZL 2007 2 0007883.4) is an immersed ultrafiltration system developed based on the Flow Split ultrafiltration membrane module. SMF is an improved process of MBR (membrane bioreactor). It uses membrane components to replace the secondary sedimentation tank in the traditional process for solid phase and liquid phase separation.