According to the classification of operation mode, ultrafiltration membranes can be divided into three types: internal pressure membranes, external pressure membranes and submerged ultrafiltration membranes.
The water inlet channel of the external pressure membrane is between the membrane filaments, and there is a certain free space for the membrane filaments, so it is more suitable for the situation of poor raw water quality and high suspended solids content;
The inlet water channel of the internal pressure membrane is the inner cavity of the hollow fiber. In order to prevent clogging, the particle size and content of the inlet water are strictly limited, so it is suitable for the working conditions of good raw water quality.
The driving force of the filtration of the immersed ultrafiltration membrane is the pressure difference between the vacuum inside the membrane tube and the atmospheric pressure. For ultrafiltration membranes with high filtration precision requirements, this pressure difference is usually not easy to meet the requirements of the required filtration driving force. Therefore, Submerged ultrafiltration is suitable for conditions with low filtration accuracy requirements, such as advanced sewage treatment.
