Ultrafiltration membrane is a microporous filtration membrane with the same pore size specification and rated pore size range of 0.001-0.02 microns.
In the field of sewage treatment and water resource reuse, MBR, also known as Membrane Bio-Reactor, is a new type of water treatment technology that combines membrane separation unit and biological treatment unit. The membrane structure used is mainly flat membrane and hollow fiber membrane, which can be divided into ultrafiltration technology according to the membrane pore size.
Ultrafiltration membrane is a microporous filtration membrane with the same pore size specification and rated pore size range of 0.001-0.02 microns. Appropriate pressure is applied on one side of the membrane, solute molecules smaller than the pore size can be screened out to separate particles with a molecular weight greater than 500 Daltons and a particle size greater than 2-20 nanometers. Ultrafiltration membrane is one of the early developed polymer separation membranes, and ultrafiltration devices were industrialized in the 1960s.
Ultrafiltration membrane is the core element of ultrafiltration equipment. One of the polymer separation membranes developed in the early stage is used in the mid-end treatment device in the preparation of ultrapure water. Since the ultrafiltration membrane is a porous material, it removes impurities in the water by physical retention, so the ultrafiltration membrane should be cleaned regularly to ensure the throughput of the ultrafiltration membrane and prolong the service life of the ultrafiltration membrane.
The cleaning method of the ultrafiltration membrane is generally determined according to the properties of the membrane and the properties of the treatment liquid. It is usually similar to reverse osmosis, that is, it is first cleaned with water, and then cleaned with different chemical detergents according to the situation. For example, an ionic solubilizer can be used for electrocoating materials, and a "bridge" type can be used for water-soluble organic coatings. solvent. Protein precipitation in the food industry can be done with prion solvents or phosphate- and silicate-based alkaline detergents. The precipitate formed on the surface of the membrane by inorganic salts can be dissolved with chelating agents such as EDTA or acids and bases. The cleaning method of ultrafiltration membrane is divided into seven steps
In the rinsing and soaking steps of a multi-stage system, all stages of the whole system can be carried out at the same time, but for high-flow circulation, it should be carried out in stages to ensure that the circulation flow is not too low or too high for the first and last stages. This can be achieved by cleaning each section with one pump each time or setting up different cleaning pumps for the flow requirements of each section.
Timely cleaning of the ultrafiltration membrane can maintain the permeation capacity and life of the membrane, and the correct cleaning method can save time and reduce the damage to the membrane element during the cleaning process. For different membrane modules, different cleaning methods can be used. For example, sponge balls can be used for mechanical cleaning of tubular modules, and backwashing can be used for hollow fiber modules. For the film used in the food industry, disinfection treatment (with NaOH and H2O2, etc.) is also required.
