What are the classifications of water purifiers according to treatment methods?
At present, water purifiers can be divided into the following 11 categories according to treatment methods:
1. Mineralization method: refers to adding mineral elements beneficial to the human body (such as calcium, zinc, strontium, etc.) into the water on the basis of purification. The purpose is to play the health effect of mineral water. Commercial water purifiers generally achieve the purpose of mineralization by adding medical stone to the water purifier, but how good is the artificial mineralization effect? It is still a controversial issue.
2. Softening method: refers to the water that removes or reduces the hardness of the water (mainly refers to the calcium and magnesium ions in the water) to a certain extent. In the process of water softening, it only softens the water quality, but cannot improve the water quality.
3. Distillation: refers to boiling water, and then collecting steam, cooling and condensing it into a liquid. Distilled water is extremely safe drinking water, but there are some issues that need to be further explored. Since distilled water does not contain minerals, this has become the reason why opponents propose that human life is prone to aging. In addition, the use of distillation is costly, consumes energy, and cannot remove volatile substances in water.
4. Reverse osmosis water purifier (permeable membrane method): A type of membrane separation technology. This method uses pressure to pass water through a synthetic membrane. The membrane only allows pure water to pass through, while pollutants are eliminated. The operation of the system depends on several factors, such as fluctuating water pressure, the life of the membrane, and the blockage of the membrane pores will affect the quality of the effluent. In addition, bacterial growth on the membrane is also a problem. The reverse osmosis system consumes a large amount of water, generally one gallon of treated water is made from 10-20 gallons. This kind of system is very expensive, and it is doing daily service, monitoring and film replacement. The advantage of this technology is the high precision of water output (for this technology, except for desalination, brackish water desalination and special industrial and engineering needs, it is generally not recommended for drinking water purification). The disadvantage is that the purified water is too pure and lacks For trace elements that are beneficial to the human body, an average of one cup of pure water will produce three cups of waste water, and electricity must be used at the same time.
5. Microfiltration and ultrafiltration: Microfiltration is a microporous filter membrane made of cellulose or polymer materials, which uses its uniform pore size to trap particles, bacteria, colloids, etc. in the water, so that they can be removed without passing through the filter membrane. This kind of microporous membrane filtration technology, also known as granular filtration technology, can filter micron or nanometer particles and bacteria. Both ultrafiltration and microfiltration are membrane separation technologies, and there is no obvious boundary between the two. The working pressure of ultrafiltration is generally about 0.3 MPa, which can remove macromolecular substances, bacteria, viruses, etc. from the water, but the flux is low.
6. Magnetization method: refers to the use of magnetic field effect to treat water, which is called water magnetization treatment. The magnetization process is the process of completing the magnetization process after the water passes through the magnet in the direction perpendicular to the magnetic line of force. The magnetization treatment of water in our country is still in the preliminary stage of practice and research so far. Foreign water purifiers do not have the requirement of magnetization function, because magnetized water does not belong to the scope of water purification, but is a medical problem.
7. Ozone and ultraviolet sterilization: These aspects can only sterilize, and can not remove heavy metals and chemical substances in the water. The dead bacteria remain in the water and become pyrogens.
8. Electrolyzer (water conditioner): The water conditioner is a newly invented product in Japan. It first purifies the water (ultrafiltration) and then electrolyzes it. The alkaline activated water corresponds to the PH value of the human body environment. , It has a health care effect on the human body and is suitable for drinking; the acidic activated water can be used for washing the face and bathing, and has a cosmetic effect. However, there are different opinions on the principle of water treatment, the water quality of the water treatment device, and the impact on the human body after use, which needs to be further explored. The disadvantage of this machine is the high cost, and the pH value of the water also depends on the electrolytic version, which requires electricity.
9. Activated carbon adsorption: can be divided into the following three forms:
- Granular activated carbon: more commonly used, it is made by chemical method or physical activation method with carbonaceous materials such as essence, coal quality, fruit shell (core) and so on. It has a lot of micropores and specific surface area, so it has a strong adsorption capacity and can effectively adsorb organic pollutants in water. In addition, during the activation process, some oxygen-containing functional groups are formed on the non-crystalline parts of the activated carbon surface. These groups make the activated carbon have chemical adsorption and catalytic oxidation and reduction properties, and can effectively remove some metal ions in the water.
- Silver-infiltrated activated carbon: Combining activated carbon and silver, not only has an adsorption effect on organic pollutants in the water, but also has a sterilization effect, and no bacteria grow in the activated carbon, which solves the problem of nitrous acid sometimes appearing in the water outlet The problem of high salt content. When the water passes through the silver-infiltrated activated carbon, the silver ions will be slowly released to play a role in disinfection and sterilization. Because activated carbon has a good effect on removing color, smell, chlorine, iron, arsenic, mercury, cyanide, phenol, etc., the sterilization effect is more than 90%, so it is used in small water purifiers.
- Fibre activated carbon: a new type of adsorption material formed by organic carbon fiber after activation treatment, with a developed microporous structure, huge specific surface area, and numerous functional groups. Foreign countries have made remarkable achievements in the use of fiber activated carbon for solvent recovery and gas purification; a lot of research work has also been done in water treatment applications.
10. Compound type: When one process is difficult to remove harmful substances in water, two or more processes are used as compound type. Such as activated carbon adsorption + ultraviolet sterilization, activated carbon adsorption + reverse osmosis, activated carbon adsorption + microfiltration (ultrafiltration), polypropylene ultrafine fiber + activated carbon + microfiltration (ultrafiltration), etc. Among the composite water purifiers, the membrane technology composite water purifier has excellent water purification performance, especially in removing microorganisms (bacteria, algae, etc.). Some of the high-quality water purifiers can directly drink the water. It has been welcomed by consumers and has become a hot spot in the current development of water purifiers.
11. Boiling method: refers to drinking tap water after boiling. This is an ancient method and is widely used in China. Boiled water can kill bacteria, but the dead body of the bacteria is still in the water and finally drunk into the stomach, and the boiling method cannot remove some chemicals and heavy metals. Even if its content is extremely low, long-term drinking is still unsafe.
From the above classification methods of water purifiers, it is not difficult to see that household water purifiers are essentially miniaturization of advanced water treatment, and their main processing objects are turbidity, chroma, odor and organic matter in tap water. It is generally composed of three parts: prefiltration (coarse filtration), adsorption, and fine filtration (microfiltration, ultrafiltration, reverse osmosis). Among them, adsorption (usually using activated carbon adsorption) and fine filtration are the main means to remove organic matter, odor and chroma in the water. The objective operating conditions directly affect the effluent quality of the water purifier. Household water purifiers serve thousands of households, but due to the large differences in water quality and water pressure conditions in the areas where they are used, users lack the necessary operating knowledge, and current product designs cannot cope with the ever-changing conditions, so water purifiers The manufacturer should consider allowing users to master certain professional knowledge, standardized installation and operation of the water purifier, so that the water quality of the effluent can achieve the desired effect, so that users can rest assured.