21, nanofiltration, reverse osmosis technology
Nanofiltration: also known as loose reverse osmosis, it is the same as the basic principle of reverse osmosis only desalination rate is slightly lower than the reverse osmosis. "Penetration" is a physical phenomenon, when two different concentrations of salt water, such as with a semi-permeable membrane separation will be found, less salt on the side of the water will be the first state membrane infiltration of salt High water side, try to add a pressure, the results can also make the infiltration stop, then the pressure is called the osmotic pressure. If the pressure increases, the water can penetrate in the opposite direction, and the salt is left. Therefore, the membrane osmosis desalination principle, that is, in salt water (such as raw water), the pressure applied to the greater than the natural osmotic pressure, so that the infiltration in the opposite direction, the water molecules in the raw water pressure to the other side of the film, into Clean water, so as to achieve the purpose of removing salt in the water, which is nanofiltration, reverse osmosis desalination principle.
22, ion exchange: the so-called ion exchange, that is, ions in water and ion exchange resin on the ions, carried out by isoelectric reaction. The ion exchange reaction process can be used as an example of the H + cation exchange resin HR and the Na + exchange reaction process in water. HR + Na + = Na ++ H + From the above equation, the cation in the ion exchange reaction (such as Na) To the resin up, and an exchangeable H on the ion exchange resin into the water. Na is transferred from the water to the resin on the process of ion exchange process. While the resin on the H exchange process into the water called the free process. Thus, due to the results of the free and permutation processes, the Na and H interchange positions, this change, is called ion exchange.
23, sterilization, disinfection
Water disinfection methods can be divided into two kinds of chemical and physical. Physical disinfection methods are heating, UV, ultrasonic and other methods; chemical methods are chlorine, ozone, heavy metal ions and other oxidants and so on. Here only on the physical disinfection method in the ultraviolet (uv) method and chemical disinfection methods in the ozone (O3) method to do a brief introduction:
UV: mercury lamp in the light, can emit ultraviolet light, this light can penetrate the bacterial cell wall, kill the micro-organisms, to achieve the purpose of disinfection and sterilization. UV disinfection is mainly used in the treatment of small drinking water. It is characterized by: strong ability to kill, contact time is short; equipment is simple, easy operation and management, water treatment after the colorless, tasteless, no poisoning hazards; will not increase the oxygen as soon as possible to kill the chloride ion. However, there is no residual chlorine as a result of the continued killing effect of mercury, and mercury lamp life is short, expensive, small amount of water treatment.
Ozone is a kind of blue at room temperature, a special fish smell of the gas, the formula for the O3. Ozone is an allotrope of oxygen, it can be decomposed into a single oxygen atom at room temperature, while a single oxygen atom is highly oxidizable. Ozone can be bacteria, fungi and other bacteria in the protein oxidation, denaturation, so that the electrolyte can not kill the role of bacteria can kill bacteria and spores, viruses, fungi, etc., and can damage the botulinum toxin, you can clear and kill the air, Water, food in the toxic substances and bacteria, in addition to odor, widely used in food production disinfection, sterilization and other processes. Ozone in the process of sterilization, sterilization process only produce non-toxic oxides, the excess ozone eventually reduced to oxygen, in the disinfection of goods on the absence of residues can be directly used for food disinfection and sterilization.