The combination of ultrafiltration membrane and RO (reverse osmosis) can prolong the water production life of RO, which is 3 times longer than the previous pure water system and saves water. The water filtered from the pure water system can be 65,438+000% sterile, salt-free, and free of minerals and other harmful substances. Pure water system is mainly used in areas where hard water and heavy metals exceed the standard, medical water, boiler water supplement, pure water production and other fields, and the filtered water quality is not suitable for long-term drinking by people and livestock.
RO(Reverse Osmosis) reverse osmosis technology is a membrane separation and filtration technology driven by pressure difference. It originated from the aerospace science and technology research in the United States in the 1960s, and then gradually turned to civilian use. At present, it has been widely used in scientific research, medicine, food, beverage, seawater desalination and other fields.
The pore size of RO reverse osmosis membrane is as small as nanometer (1 nm = 10-9 m). Under a certain pressure, H2O molecules can pass through RO membrane, while impurities such as inorganic salts, heavy metal ions, organic substances, colloids, bacteria and viruses in source water cannot pass through RO membrane, thus strictly distinguishing permeable pure water from impermeable concentrated water.
The pure water conductivity of ordinary tap water filtered by RO membrane is 5 μ s/cm (after RO membrane filtration, the outlet conductance = inlet conductance × desalination rate, and the desalination rate of imported reverse osmosis membrane can reach above 99%, which can be guaranteed to be above 97% in five years. Two-stage reverse osmosis can be used if the effluent conductivity is high. After simple treatment, the hydraulic conductivity is less than 1μs/cm), which meets the third-class water use standard of national laboratory. After circulating filtration by atomic ion exchange column, the effluent resistivity can reach18.2m. Cm, exceeding the national first-class laboratory water standard (GB 6682-92).
At present, the main difficulty is to develop a cheap, stable and long-term pressure-free reverse osmosis membrane. 265438+At the beginning of the 20th century, China has mastered the production technology of independent reverse osmosis membrane. With the strong support of the state, this plan was included in the special plan for the key development of high-tech industrialization of the State Planning Commission, and was undertaken and successfully developed by Hangzhou Big Dipper Membrane Products Co., Ltd., a subsidiary of Hangzhou Water Treatment Research and Development Center of the State Oceanic Administration. At present, 95% of the reverse osmosis membrane market is imported membrane, and domestic membrane only occupies about 5% of the market. The reverse osmosis technology in China still has a long way to go.
Drinking range
Preparation of space water, purified water and distilled water; Water for alcohol production and alcohol reduction; Preparation of water for pharmaceutical, electronic and other industries; Concentration, separation, purification and water production of chemical processes; Boiler make-up water softened water; Desalination of seawater and brackish water; Water and wastewater treatment in papermaking, electroplating, printing and dyeing industries.
As a new and efficient operation technology of fluid separation unit, membrane separation technology represented by polymer separation membrane has made remarkable rapid development in the past 30 years and has been widely used in various fields of national economy.