Comparison of UF、NF、MF、RO Membranes

Ultrafiltration (UF).

      The filtration precision is 0.001-0.1 micron, which belongs to one of the high-tech in the 21st century. It is a kind of membrane separation technology using pressure difference, which can filter out rust, sediment, suspended matter, colloid, bacteria, macromolecular organic matter and other harmful substances in water, and can retain some mineral elements that are beneficial to human body. It is the core component in the production process of mineral water and mountain water. The recovery rate of water in the ultrafiltration process is up to 95% or more, and it can be easily flushed and backwashed, not easy to clog, and has a relatively long service life. Ultra-filtration does not need to add electricity and pressure, relying only on the tap water pressure can be filtered, the flow rate is large, the use of low cost, more suitable for the comprehensive purification of household drinking water. Therefore, the future of drinking water purification will be based on ultrafiltration technology, and combined with other filtration materials to achieve a wider range of treatment, more comprehensive elimination of pollutants in the water.

Nanofiltration (NF).

      The filtration accuracy is between ultrafiltration and reverse osmosis, the desalination rate is lower than reverse osmosis, and it is also a membrane separation technology that requires electricity and pressure, and the water recovery rate is lower. This means that the process of making water with nanofiltration membrane must waste nearly 30% of tap water. This is not acceptable for the average household. It is generally used for industrial pure water manufacturing.

Microfiltration (MF).

      Filtration accuracy is generally in 0.1-50 microns, common various PP cartridge, activated carbon cartridge, ceramic cartridge, etc. belong to the category of microfiltration, used for simple coarse filtration, filtering water sediment, rust and other large particles of impurities, but can not remove bacteria and other harmful substances in the water. Cartridge usually can not be cleaned, for disposable filter materials, need to be replaced frequently. ① PP cotton core: generally used only for coarse filtration with low requirements to remove large particles such as silt and rust in water. ② Activated carbon: It can eliminate the color and odor in the water, but cannot remove the bacteria in the water, and the removal effect of sediment and rust is also very poor. ③ Ceramic cartridge: the minimum filtration accuracy is only 0.1 micron, usually with small flow and not easy to clean.

Reverse osmosis membrane (RO membrane).

        RO is the abbreviation of English Reverse Osmosis membrane, meaning (reverse osmosis), the general flow of water is from low concentration to high concentration, once the water is pressurized, it will flow from high concentration to low concentration, which is also known as the principle of reverse osmosis: because the pore size of RO membrane is five parts per million of a hair (0.0001 micron) , Therefore, only water molecules and some beneficial mineral ions can pass through, while other impurities and heavy metals are discharged from the waste pipe. All seawater desalination processes and astronaut wastewater recycling treatment use this method, so the RO membrane is also known as a high-tech artificial kidney outside the body.

The origin of RO reverse osmosis.

      In 1950, the American scientist DR.S.Sourirajan once unintentionally found that a seagull flying at sea took a big mouthful of seawater from the surface and spit out a small mouthful of seawater after a few seconds, and had doubts because animals breathing from lungs on land can never drink high-salt seawater. After dissection, it was found that there was a membrane in the gull's body, and the membrane was very precise, and the seawater was pressurized after being inhaled by the gull, and then the water molecules were transformed into fresh water through the membrane by pressure, while the seawater containing impurities and highly concentrated salt was spit out of the mouth, which was the basic theoretical structure of the reverse osmosis method; and was applied by the University of Florida in 1953. In 1960, the U.S. federal government supported the U.S. U.C.L.A. University School of Medicine Professor Dr. Sidney Lode with Dr. DR.S. Soirirajan began to research reverse osmosis membrane, about $400 million a year to invest in research, in order to apply to the use of astronauts, so that spacecraft do not have to carry a lot of drinking water into space. Until 1960 into the research work of more and more scholars, experts, so that the quality and quantity of more sophisticated, thus solving the problem of human drinking water.

What is reverse osmosis?