The filtration precision is 0.001-0.1 μ m, which is one of the high-tech in the 21st century. It is a membrane separation technology which can filter out rust, sediment, suspended matter, colloid, bacteria, macromolecule organic matter and other harmful substances in water, and can retain some mineral elements beneficial to human body. It is the core component of the production technology of mineral water and mountain spring water. The recovery rate of water in ultrafiltration process is up to 95%, and it can be easily washed and backwashed, which is not easy to block and has a relatively long service life. Ultrafiltration does not need to be charged and pressurized. It can be filtered only by tap water pressure. It has large flow and low cost. It is more suitable for the comprehensive purification of domestic drinking water. Therefore, in the future, the purification of drinking water will be mainly ultrafiltration technology, combined with other filtering materials, to achieve a wider treatment range and to eliminate the pollution in water more comprehensively.
The filtration precision is between ultrafiltration and reverse osmosis, and the desalination rate is lower than reverse osmosis. It is also a membrane separation technology which needs to be electrified and pressurized, and the water recovery is low. That is to say, in the process of making water with nanofiltration membrane, nearly 30% of tap water will be wasted. This is unacceptable to the general family. It is generally used in the manufacture of industrial pure water.
The filtration accuracy is generally 0.1-50 μ M. common PP filter elements, active carbon filter elements, ceramic filter elements are all micro filtration categories, which are used for simple coarse filtration, filtering of sediment, rust and other large particles impurities in the water, but can not remove harmful substances such as bacteria in water. Filter element can not be cleaned normally. It is disposable filter material and needs to be replaced frequently. ① Ppcotton core: generally only used for coarse filtration with low requirements, removing sediment, rust and other large particles in water. ② Active carbon: it can eliminate the color and odor in water, but it can not remove bacteria in water, and the removal effect of sediment and rust is also very poor. ③ Ceramic filter element: the minimum filtration accuracy is only 0.1 μ m, usually the flow rate is small and it is not easy to clean.
Ro is the abbreviation of reverse osmois membrane, which means (reverse osmosis). Generally, water flows from low concentration to high concentration. Once pressurized, water will flow from high concentration to low concentration, that is, the so-called reverse osmosis principle: since the pore diameter of RO membrane is 5 / 1 million (0.0001 μ m) of hair silk, Generally, the naked eye can not see that bacteria and viruses are 5000 times of it. Therefore, only water molecules and some mineral ions beneficial to human body can pass through, and other impurities and heavy metals are discharged from waste water pipes. All desalination processes and space man wastewater recovery and treatment are all adopted by this method. Therefore, RO membrane is also called high-tech artificial kidney in vitro.
What is reverse osmosis?
Reverse osmosis is a new membrane separation technology developed in 1960s. It is a process of separation of solvent and solute in solution by reverse osmosis membrane under pressure. Reverse osmosis is the full name of reverse osmosis, abbreviated as "ro".
Principle of reverse osmosis:
First, we should understand the concept of "penetration". Permeability is a physical phenomenon. When two kinds of water containing different salts, such as separating with a semi permeable film, it is found that the water on the side with less salt content will penetrate into the water with high salt content through the membrane, and the salt content is not permeable. In this way, the salt concentration on both sides will be gradually integrated to the same level. However, to complete this, this is to be completed The process takes a long time, which is also known as the osmotic pressure. But if a pressure is added on the water side with high salt content, the result can also stop the above-mentioned infiltration, and the pressure is called the osmotic pressure. If the pressure increases again, it can penetrate in the opposite direction, while the salt is left. Therefore, the principle of reverse osmosis desalination is to apply pressure greater than natural osmosis pressure in water with salt (such as raw water), so that the permeation will be carried out in the opposite direction, and the molecular pressure of water in raw water is pressed to the other side of membrane, and then it will be clean water, so as to remove impurities and salts in water.
Origin of RO ro ro:
In 1950, dr.s.sourirajan, an American scientist, once accidentally discovered that gulls sip a large sea water from the sea when they fly at sea. After a few seconds, they spit out a small mouth of sea water, and have doubts because animals breathing by lungs on land can never drink high salt water. It was found that there was a film in gulls, which was very precise. The seawater was inhaled into the body and pressurized. Then, the water molecules were penetrated through the membrane to fresh water by pressure action. The seawater containing impurities and high concentrated salt was spewed out of the mouth, which was the basic theoretical framework of the reverse osmosis method. In 1953, the basic theoretical framework of the reverse osmosis method was established by University of Florida was applied to desalination and salt removal equipment. Dr.s.sidney, Professor of Medical College of U.C.L.A University, was supported by the federal government in 1960 Lode, in cooperation with dr.s.soirarajan, started to study the reverse osmosis membrane, and invested about 400 million dollars a year to study it to be used by space people, so that the spacecraft would not carry a large amount of drinking water to lift off the air. Until 1960, more and more scholars and experts were put into research work, which made the quality and quantity more refined, thus solving the problem of human drinking water.