The membrane is a material with selective separation function. The process of separating, purifying, and concentrating different components of a feed liquid by selective separation of membranes is referred to as membrane separation. It differs from conventional filtration in that the membrane can be separated in the molecular range, and the process is a physical process that does not require phase changes and additives. The pore size of the membrane is generally on the order of micrometers. According to the difference in pore diameter (or the amount of interception separation), the membrane can be divided into a power membrane, an ultrafiltration membrane, a nanofiltration membrane and a reverse osmosis membrane, which can be classified into inorganic according to different materials. Membranes and organic membranes, inorganic membranes mainly have only microfiltration grade membranes, mainly ceramic membranes and metal membranes. The organic film is made of a polymer material such as cellulose acetate, aromatic polyamide, polyether sulfone, polyfluoropolymer or the like.