Membrane separation technology is a process of component separation by using the difference of the penetration rate of each component in the fluid to the membrane. Depending on the characteristics of selective permeability of the membrane, small molecular substances can freely pass through the semi-permeable membrane. For large molecular substances, the selective membrane does not have permeability and is intercepted, so as to complete the purpose of separation, purification and concentration of materials in multiple components. According to the different driving force of mass transfer, membrane separation can be divided into microfiltration, ultrafiltration, nanofiltration, reverse osmosis, electrodialysis, dialysis and osmosis. Among them, the driving force of microfiltration, ultrafiltration, nanofiltration and reverse osmosis is pressure difference, but the pressure difference is different. The pressure difference required by reverse osmosis is the largest, followed by nanofiltration and ultrafiltration, and the pressure difference required by microfiltration is the smallest. The driving forces of electrodialysis, dialysis and osmosis are potential difference, concentration difference and chemical potential difference in turn. At present, the most commonly used membrane separation technologies in the industrial field are microfiltration, ultrafiltration, nanofiltration, reverse osmosis and electrodialysis.