How to prevent needle roller bearings from rusting

Before we introduce the anti-rust method of needle roller bearings, we should first understand what causes the bearing to rust. What are the main factors that affect corrosion of needle roller bearings? Then prescribe the right medicine
The corrosion of needle roller bearings is caused by various internal and external factors, which can be summarized as follows:
(1) The material of the needle roller bearing itself is made of bearing steel, and the chemical composition and structure of the bearing steel itself may be oxidized by air into embroidery.

(2) The surface finish of the needle roller bearing (battery corrosion with poor oxygen concentration);

(3) The composition and pH of the solution in contact with the surface of the bearing;

(4) The ambient temperature and humidity of the stored bearings;

(5) Various environmental media in contact with the bearing surface.
So what is the method of anti-rust of ring needle roller bearings?
1. First of all, the bearing surface cleaning: the cleaning must be based on the nature of the surface of the rust and the conditions at that time, and the appropriate method must be selected. Generally, it is more washed with solvents, chemical treatment cleaning method and mechanical cleaning method.

2. The surface of the bearing can be dried and cleaned with filtered dry compressed air, or dried with a dryer of 120 to 170 degrees Celsius, or dried with clean gauze.

Method of applying anti-rust oil to the surface of the bearing:

3. Soaking method: Needle roller bearings are soaked in anti-rust grease and let their surface adhere to a layer of anti-rust grease. The thickness of the oil film can be achieved by controlling the temperature or viscosity of the anti-rust grease.

4. There is also human hand sweat will cause rust of needle roller bearings, human sweat is a colorless transparent or light yellow with a salty taste of weak acidity of the liquid, its pH value of 5 ~ 6. In addition to containing sodium, potassium, calcium, magnesium salts, it also contains a small amount of organic acids such as urea, lactic acid, and citric acid. When sweat comes into contact with the bearing surface, a sweat film is formed on the bearing surface, which causes electrochemical effects on the bearing, corrodes the bearing, and thus produces embroidery. People sweating is inevitable, to prevent hand sweat caused by rust, that is, production personnel in the assembly of bearings should wear gloves, finger sleeves, or use special tools to take the bearing, do not casually touch the surface of the bearing with their hands.

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What are the scope of application of stamped outer ring bearings?

1. Stamped outer ring needle roller bearing split hole type and sealing type, stamped outer ring needle roller bearing without inner ring, direct contact with the surface, so that the processing accuracy and heat treatment hardness of the bearing should be the same. Scope of application: Cage stamped outer ring needle roller bearings are suitable for high speed, heavy duty, gearbox or textile machinery for machine tools, automobiles, motorcycles. The ring frame of the needle roller bearing without holding the needle roller, if filled with needle roller, is suitable for heavy duty operating conditions. For the flat frame of the shaft, the wing end, etc.

2, solid ferrule needle roller bearing, solid ferrule needle roller bearing is the use of Na type and RNA type. Scope of application: solid ring needle roller bearings, machine tools, automotive transmissions. It has the advantage of a small cross-sectional size for radial bearing radial loads. Standard solid ferrule needle roller housing, such a high speed, adapted to the requirements of the machine tool, automotive gearbox.

3. Scope of application of needle roller bearings: printing machinery, forage machinery, agricultural machinery, roller CNC equipment track, conveyor line.

4. Assemble needle roller and cage. Needle roller and cage assemblies are actually needle roller bearings without an inner ring, and are suitable for use: this type of bearing, transmission, motorcycle, car connecting rod big and small end. Due to the increase in cylinder temperature, the bearing temperature is high.

We are a company specializing in the production and operation of stamped outer ring needle roller bearings, if you have any needs please contact my [email protected]

Manufacturing process of industrial pure water equipment

Manufacturing process of pure water equipment


Pure water equipment process flow: primary reverse osmosis pure water process flow: raw water – > multi-media filter – > activated carbon filter – > softened filter – > softened water tank – > security filter – > RO reverse osmosis system – > pure water tank – > water supply point secondary reverse osmosis pure water process flow: raw water – > multi-media filter – > activated carbon filter – > softened filter – > softened water tank – > security filter – > primary reverse osmosis device – > Secondary reverse osmosis device – > pure water tank – > water use point

Product application fields:


1. Ultra pure water equipment for electronic industry, microelectronic products, semiconductors, picture tubes and other high-purity water equipment for manufacturing, computer circuit boards and other integrated circuit boards, high-purity water equipment for production of batteries, lithium batteries, solar cells, dry-type batteries and other pure water

2. Deionized water equipment for surface treatment, deionized water for glass coating, high-purity water equipment, pure water and ultra pure water equipment for ultrasonic cleaning

3. Boiler make-up water, cooling water equipment, softened water for high, medium and low pressure boilers in power plants, pure water equipment, air conditioning, cold storage and other circulating cooling circulating water and other industrial circulating water treatment equipment

4. Purified and separated pure water for raw material intermediates, non heat source water, pure water for pharmaceutical, injection, high-purity water, sterile water and other products, pure water for oral liquid production, engineering hemodialysis, biochemical analysis pure water

5. Ultra pure water equipment for metallurgy and chemical industry tungsten molybdenum vanadium metallurgical pure water machine, ultra pure water equipment for chemical reagent production, pure water machine for chemical agents, ultra pure water equipment

Tianjin Decho is a professional supplier on submerged membrane filtration, if you need any for your projects, pls do not hesitate to contact us by email [email protected]

Introduction to submerged ultrafiltration process

SMF submerged membrane filtration technology is a new type of membrane filtration separation technology. It is a new type of membrane filtration process derived from the combination of low-pressure hollow fiber membrane technology and continuous membrane filtration technology. It uses the hollow fiber ultrafiltration membrane module to place the membrane directly in the membrane pool filled with water to be treated. Through the negative pressure suction of the self-priming pump, the water passes through the membrane surface and is extracted from the inner side of the hollow fiber membrane, while the pollutants are retained on the membrane surface. Through regular air washing, backwashing, sewage discharge, on-line dosing cleaning and off-line chemical enhanced cleaning, the combined process can eliminate membrane pollution and effectively restore the membrane flux to ensure the normal operation of the system. Submerged membrane filtration technology can replace the filtration process in the traditional water treatment process, and is widely used in wastewater treatment, water purification, reclaimed water reuse, seawater desalination and other fields. Its characteristics mainly include the following aspects:

① High solid-liquid separation efficiency. Due to the high efficiency of the membrane, the particles, colloids, macromolecular organics and bacteria in the sewage are intercepted at the inlet side of the membrane;

② The membrane pressure difference is evenly distributed along the length of the hollow fiber membrane, and there is no pressure drop loss on the water inlet side of the membrane;

③ Simple pretreatment requirements and strong anti pollution ability;

④ Compact equipment and small floor space;

⑤ It is suitable for large-scale water plant applications, and the output of a single system can reach more than 40000 m3/d;

⑥ Low energy consumption and operation cost.

In the 1980s, foreign countries have begun to study and apply submerged ultrafiltration in various fields of water treatment industry. In the early 1990s, a large water plant in Singapore chose the submerged ultrafiltration membrane system to upgrade the V-shaped filter in phase I. on the premise of maintaining the treatment scale, the quality of produced water was improved, and an engineering basis was provided for the phase II project to improve the treatment volume and quality. Subsequently, the submerged membrane filtration system has also been applied in the new construction and upgrading of the water supply plant.

Submerged element

The common polymer materials for submerged membrane components are polyvinylidene fluoride (PVDF), polyethylene (PE) and polypropylene (PP). PVDF has a wide range of applications at home and abroad because of its excellent physical and chemical properties (strength and corrosion resistance). There are also porous ceramic films prepared from inorganic materials such as Al2O3, ZrO2, TiO2 and SiO2. Comparatively speaking, the ceramic membrane has good chemical stability, acid, alkali and organic solvent resistance, and high mechanical strength, but it is expensive.

Submerged ultrafiltration has low energy consumption and is suitable for the transformation of sand filter station. The larger the project scale, the more obvious the advantages. For large projects, if one ton of water is treated, 0.1 kilowatt hour of electricity can be saved, which can save considerable operating costs. Moreover, the submerged process has small floor area, relatively loose requirements for inlet water quality, stable and excellent outlet water quality, and can make full use of the remaining site of the sewage plant. It is one of the options for the transformation of large-scale waterworks and municipal sewage plants in the future.

Tianjin Decho is a professional supplier on submerged membrane filtration, if you need any for your projects, pls do not hesitate to contact us by email [email protected]

Basic knowledge of water treatment

1. What is the hardness of water?

Some metal cations in water are combined with some anions. During the heating process of water, due to evaporation and concentration, scale is easy to form, which is attached to the heating surface and affects the heat conduction. We call the total concentration of these metal ions in water as the hardness of water. For example, the common metal ions in natural water are calcium ion (Ca +) and magnesium ion (Mg +), which are combined with anions in water such as carbonate ion (CO3 -), bicarbonate ion (HCO3 -), sulfate ion (SO4 -), chloride ion (Cl -) and nitrate ion (NO3 -) to form the hardness of carbonate, bicarbonate, sulfate, chloride and nitrate of calcium and magnesium. Iron, manganese, zinc and other metal ions in water will also form hardness, but they can be omitted due to their small content in natural water. Therefore, the total concentration of Ca + and Mg + is usually regarded as the hardness of water. The hardness of water has a great impact on boiler water. Therefore, the water should be softened or demineralized according to the requirements of boiler water quality with different parameters.

2. What are the hardness of water ?

The hardness of water is divided into carbonate hardness and non carbonate hardness.

3. Carbonate hardness

It is mainly the hardness formed by bicarbonate of calcium and magnesium, and a small amount of carbonate hardness. Bicarbonate hardness is decomposed into sediment after heating and removed from water, so it is also called temporary hardness.

4. Non carbonate hardness

It is mainly the hardness formed by sulfate, chloride and nitrate of calcium and magnesium. This kind of hardness cannot be removed by heating decomposition, so it is also called permanent hardness, such as CaSO4, MgSO4, CaCl2, MgCl2, Ca (NO3) 2, Mg (NO3) 2, etc.

The sum of carbonate hardness and non carbonate hardness is called total hardness. The content of Ca + in water is called calcium hardness, and the content of Mg + in water is called magnesium hardness. When the total hardness of water is less than the total alkalinity, the difference between them is called negative hardness.

5. What is colloidal substance in water?

Colloidal substances in water refer to particles with a diameter of 0.1-0.001 microns. Colloids are collections of many molecules and ions. The inorganic mineral colloid in natural water is mainly iron A compound of aluminum and silicon. The organic colloidal substances in natural water are mainly humic substances produced by the decay and decomposition of the limbs of plants and animals. Among them, the humus content in lake water is the most, so it often makes the water yellow green and brown. Due to the small particles, light weight and large surface area per unit volume of colloidal material, its surface has great adsorption capacity, often adsorbing a large amount of ions and electricity. Similar colloids repel each other because they have the same charge. They can’t adhere to each other in water and are in a stable state. Therefore, colloidal particles cannot be removed by gravity. Generally, agents are added to water to destroy its stability, so that colloidal particles increase and settle for removal.

6. What is the total solids of water Dissolved and suspended solids?

All impurities in water except dissolved gases are called solids, and the solids in water are dissolved solids and suspended solids. The sum of the two is called the total solid of water.

Dissolved solids refer to various inorganic salts that are still dissolved in water after filtration organic compound. Suspended substances such as microorganisms.

The determination of total solids is obtained by steaming dry water and then weighing. Generally, the steaming dry temperature is controlled at 105-110 degrees.

7. What is the salt content of water?

The salt content of water (also known as salinity) is the amount of salt in water. Since various salts in water generally exist in the form of ions, the salt content can also be expressed as the sum of various cations and anions in water.

The salt content of water is different from that of dissolved solids, because dissolved solids include not only dissolved salts in water, but also organic substances. At the same time, the meaning of salt content of water is different from that of total solids, because total solids include not only dissolved solids, but also suspended solids that do not dissolve water, so the quantity of dissolved solids and total solids is higher than that of salt content.

8. What is the turbidity of water?

Because the water contains suspended and colloidal particles, the original colorless and transparent water produces turbidity. The degree of turbidity is called turbidity. Turbidity is the expression of different sizes of water Different relative densities Suspended solids of different shapes Colloidal substance The effects of plankton and microorganisms on light. It does not directly indicate the content of impurities, but is related to the amount of impurities.

Turbidity is an optical effect. It is the degree to which light is blocked when passing through the water layer. It indicates the ability of the water layer to scatter and absorb light.

Controlling turbidity is not only an important content of industrial water treatment, but also an important water quality index. According to different uses of water, the requirements for turbidity are different. The turbidity of domestic drinking water shall not exceed 1 NTU; The turbidity of circulating cooling water make-up water is less than 2-5 NTU, and the reverse osmosis demineralized water inlet is required to be less than 0.5 NTU

9. What is the chromaticity of water?

The chromaticity of water is an index for quantitative color test of natural water or treated water. Natural water often shows light yellow Different colors such as light brown or yellow green. The reason for the color is due to the humus dissolved in water Caused by organic or inorganic substances. In addition, when the water body is polluted by industrial wastewater, it will also show different colors. These colors are divided into true colors and surface colors. True color is caused by dissolved substances in water, that is, the color after removing suspended substances in water. The surface color is the color when the suspended solids in the water are not removed. The quantitative degree of these colors is chromaticity.

Industrial wastewater may make the water body produce various colors, but the humus in the water The presence of suspended sediment and insoluble minerals will also make the water color. For example, clay can make the water yellow, iron oxide can make the water brown, sulfide can make the water yellow, algae can make the water green, rotten organic matter can make the water black brown and so on.

10. What is the resistivity of water?

When measuring the conductivity of water, it is related to the resistance value of water. If the resistance value is large, the conductivity is poor, and if the resistance value is small, the conductivity is good.

The resistivity of water is related to the amount of salt in water Ion content in water The charge number of ions is related to the movement speed of ions. Therefore, the pure hydraulic resistivity is large, and the ultra pure hydraulic resistivity is even greater. The purer the water, the greater the resistivity.

16. What is the conductivity of water?

The conductivity of water is commonly called conductivity; Conductivity reflects the amount of salt in water and is an important indicator of the purity of water. The purer the water, the less salt content, the greater the resistance and the smaller the conductivity. Ultrapure water can hardly conduct electricity. The conductance is equal to the reciprocal of the resistance.

Since the dissolved salts in aqueous solution exist in ionic state, they have conductivity, so the conductivity can also indirectly represent the content of dissolved salts (salt content)

11. What is the pH value of water?

Negative logarithm of hydrogen ion concentration in water.

12. What is electrolyte?

Electrolytes are substances that can conduct electricity in aqueous solution, while non electrolytes do not have this ability. All acids Alkali Salt is an electrolyte. The reason why electrolyte has conductivity in water is that it dissociates or ionizes in water to produce positively charged cations and negatively charged anions.

13. What is chemical oxygen demand (COD)?

The amount of oxidation consumed when a certain strong oxidant is used to treat water samples under certain conditions. It is an indicator of the amount of reducing substances in water. The reducing substances in water are mainly organic substances. Therefore, cod is often used as an indicator to measure the content of organic matter in water. The higher the COD, the more serious the water is polluted by organic matter.

14. What is biochemical oxygen demand (BOD)?

Under aerobic conditions, due to the action of microorganisms, the amount of oxygen consumed when the organic substances that can be decomposed in water are completely oxidized and decomposed is called biochemical oxygen demand, which is referred to as biochemical oxygen demand for short. The amount of BOD indicates the degree of organic pollution of water body and reflects the quality of water quality.

15. What is total oxygen demand (TOD)?

The measurement of total oxygen demand is the amount of oxygen consumed by burning and oxidizing organic matter at 900 ℃ in a special burner with platinum as catalyst. The measurement result is closer to the theoretical oxygen demand than cod.

16. What is total organic carbon (TOC)?

The content of organic matter in water is expressed by the amount of carbon, the main element in organic matter, which is called total organic carbon.

TOC is determined by gasification and combustion of organic matter in water samples at high temperature to generate CO2. The total organic carbon can be known by measuring the amount of CO2 generated.

If the water sample is filtered through 0.2um microporous membrane, the measured carbon is dissolved organic carbon (DOC).

TOC and DOC are commonly used water quality indicators.

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What are the reasons for the decline of resistivity during the operation of EDI ultrapure water equipment?

The reasons for the decline of resistivity during the operation of EDI ultrapure water equipment are related to the pollution of inlet water quality, pressure, flow, voltage and inlet water quality. The following is a brief introduction to the reasons for the decline of resistivity of EDI ultrapure water equipment.

1. The effluent of reverse osmosis equipment is unqualified (including conductivity, hardness, variable metal, etc.)

If the salt content of raw water is high, it is recommended to use bipolar RO reverse osmosis equipment as pre desalting, and its conductivity shall be maintained at 1 ~ 3 μ S / cm is preferred; The influent has high CO2 content, so it is recommended to use degassing membrane or degassing tower to remove CO2. If the pH deviates too much from neutral, adjust the pH to make the pH value of EDI influent at 7 ~ 8.

2. There is a problem with the current control of EDI system

The working current increases and the quality of produced water keeps getting better. However, if the current is increased after increasing to the high point, due to the excessive amount of H + and oh – ions produced by water ionization, a large number of surplus ions act as current carrying ions for conduction, in addition to being used for regenerating resin. At the same time, due to the accumulation, blockage and even reverse diffusion of a large number of current carrying ions during their movement, the quality of produced water is reduced.

3. PH change

The influent CO2 content of EDI system is high. If the CO2 content is greater than 10ppm, EDI system cannot prepare high-purity water.

4. Iron pollution

Iron pollution in the operation of EDI system is the main reason for the progressive decline of water production resistance. If ordinary steel pipes are used in the raw water and pretreatment system without internal anti-corrosion treatment, the iron content in the system will increase. After the iron is corroded, it will be dissolved in the water in the form of Fe (OH) 2 and further oxidized to Fe (OH) 3. Fe (OH) 2 is colloidal and Fe (OH) 3 is suspended. The resin has strong affinity for iron, which will cause irreversible reaction after being adsorbed by the resin. In the treatment of anion and cation exchange water, the anion and cation beds will be regenerated or cleaned to remove most of the iron in the resin. However, in the operation of EDI equipment, there is no regeneration and cleaning, and the trace iron in the water will adhere to the anion and cation resin and anion and cation film. Iron has strong conductivity. Before it can react with the cationic resin, it is close to the negative membrane water in the EDI module and migrates to the positive membrane under the action of high current. Pure iron ions are easy to penetrate, while colloidal iron compounds are not easy to penetrate the positive membrane. They are adsorbed on the surface of the positive membrane and pollute the negative and positive membranes, which leads to the decline of the working performance of EDI components, poor water production quality and progressive reduction of resistance value.

5. Organic pollution

The organic colloid in the water inlet of EDI pure water equipment is polluted, and reverse osmosis can only remove the organic colloid with relative molecular weight greater than 200. If the molecular weight is lower than 200, it will enter the EDI system. This part of low molecular weight material is adsorbed on the mesh of the skeleton and the surface of the anion and cation membrane by the anion and cation exchange resin in the module, which hinders the replacement reaction of anion and cation and the speed of water ions penetrating the anion and cation membrane, resulting in the decline of EDI working performance and the decline of water resistivity.

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Treatment methods for different kinds of water

In the environmental protection water treatment industry, the commonly used water treatment methods generally include:

(1) Sediment filtration method

(2) hard water softening method

(3) Activated carbon adsorption method

(4) deionization method

(5) Reverse osmosis method

(6) excess filtration method

(7) Distillation method,

(8) ultraviolet disinfection method

(9) Biochemical method, etc

Now, the principles and functions of these water treatment methods are introduced here. According to different water quality, the commonly used water treatment methods are summarized as follows:

1、 Sediment filtration

The purpose of sediment filtration method is to remove suspended particulate matter or colloidal matter from the water source. If these particles are not removed, they will damage other precision filtration membranes of dialysis water or even block the waterway. This is an ancient and simple water purification method, so this step is often used in the preliminary treatment of water purification, or if necessary, several filters will be added to the pipeline to remove large impurities.

There are many kinds of filters used to filter suspended particulate matter, such as mesh filter, sand filter (such as quartz sand) or membrane filter. As long as the particle size is larger than the size of these holes, it will be blocked.

There is another problem worth noting in the sediment filtration method, because the particulate matter is constantly blocked and accumulated. There may be bacteria on the surface of these substances to reproduce here and release toxic substances through the filter, resulting in pyrogen reaction. Therefore, the filter should be replaced frequently. In principle, when the pressure drop between inlet and outlet increases to five times of the original, the filter needs to be replaced.

2、 Hard water softening method (softened water equipment)


The softening of hard water needs to use ion exchange method. Its purpose is to use cation exchange resin to exchange calcium and magnesium ions in hard water with sodium ions, so as to reduce the concentration of calcium and magnesium ions in water source.

If there is no softening of cations in the process of water treatment, it is not only the deposition of calcium and magnesium on the reverse osmosis membrane, which will reduce the efficiency and even destroy the reverse osmosis membrane. At the same time, patients are also easy to get hard water syndrome. The hard water softener will also cause the problem of bacterial reproduction, so the equipment needs to have the function of back flushing. After a period of time, it needs to be back flushed once to prevent too many impurities from adsorbing it.

3、 Activated carbon filter

Activated carbon is made of wood, sawdust, fruit core, coconut shell, coal or oil residue, which is carbonized by dry distillation at high temperature. After being made, it needs to be activated by hot air or steam. Its main function is to remove chlorine, ammonia chloride and other dissolved organic substances with molecular weight of 60 to 300 daltons. The surface of activated carbon is granular and the interior is porous. There are many capillaries about 1onm ~ La in the pores. The internal surface area of 1G activated carbon is as high as 700-1400m2, and the inner surface of these capillaries and particle surface are the place of adsorption.

4、 Deionization method

The purpose of deionization method is to eliminate inorganic ions dissolved in water. Like hard water softener, it also uses the principle of ion exchange resin. In this, two resins are used – cation exchange resin and anion exchange resin. Cation exchange resin uses hydrogen ion (H +) to exchange cations; Anion exchange resin uses hydroxyl ions (OH -) to exchange anions.

After the adsorption capacity of these resins is exhausted, they also need to be reduced, and cation exchange resins need strong acid to be reduced; On the contrary, anions need strong bases to reduce. If the anion exchange resin is exhausted without reduction, fluorine with weak adsorption will gradually appear in the dialysis water, resulting in chondropathy, osteoporosis and other bone diseases; If the cation exchange resin is exhausted, hydrogen ions will also appear in the dialysis water, resulting in the increase of water acidity. Therefore, whether the deionization function is effective needs to be monitored from time to time.

It is generally judged by the resistance coefficient or conductivity of water quality. The ion exchange resin used in deionization method will also cause bacterial reproduction and bacteremia, which is worthy of attention.

5、 Reverse osmosis

Reverse osmosis can effectively remove inorganic matter, organic matter, bacteria, pyrogen and other particles dissolved in water. It is an important link in the treatment of dialysis water.

The purification effect of reverse osmosis can reach the level of ions. The commonly used semi permeable membrane materials for reverse osmosis water treatment include fibrous membrane, aromatic polyamides, polyimide or polyfuranes, and its structural shapes include spiral wound, hollow fiber and tubular.

If no pretreatment is done before reverse osmosis, dirt is easy to accumulate on the osmosis membrane, such as calcium, magnesium and iron plasma, resulting in the decline of reverse osmosis function; Some membranes (such as polyamide) are easy to be damaged by chlorine and ammonia chloride. Therefore, activated carbon and softener should be pretreated before reverse osmosis membrane. Therefore, the preparation of water for hemodialysis analysis and release is a step.

6、 Excess filtration

Similar to reverse osmosis, ultrafiltration uses semi permeable membrane, but it cannot control the removal of ions because the pore size of the membrane is large, about 10-200a. Only bacteria, viruses, pyrogens and particles can be excluded, while water-soluble ions cannot be filtered.

The main function of ultrafiltration method is to act as the pretreatment of reverse osmosis method to prevent the reverse osmosis membrane from being polluted by bacteria. It can also be used in the next step of water treatment to prevent the upstream water from being polluted by bacteria in the pipeline. Generally, the difference between inlet pressure and outlet pressure is used to judge whether the excess filter membrane is effective. Similar to activated carbon, it usually uses the back flushing method to remove the impurities attached to it.

7、 Distillation method

Distillation is an ancient but effective water treatment method. It can remove any nonvolatile impurities, but it can not eliminate volatile pollutants. It needs a large water storage tank to store. This water storage tank and delivery pipe are an important cause of pollution. At present, the water for hemodialysis is not treated in this way.

8、 Ultraviolet disinfection


Ultraviolet disinfection is one of the commonly used methods at present. Its sterilization mechanism is to destroy the life genetic material of bacterial nucleic acid and make it unable to reproduce. The major reaction is that the pyrimidine base in the nucleic acid molecule becomes a dimer. Generally, the artificial ultraviolet energy of 253.7 nm wavelength of low-pressure mercury discharge lamp (sterilization lamp) is used. The principle of ultraviolet sterilization lamp is the same as that of fluorescent lamp, except that the interior of the lamp tube is not coated with fluorescent substances. The material of the lamp tube is quartz glass with high ultraviolet penetration rate. General ultraviolet devices can be divided into irradiation type, immersion type and running water type according to their purposes.

9、 Biochemical method

Biochemical water treatment method uses various bacteria and microorganisms existing in nature to decompose the organic matter in the wastewater into harmless substances, so that the wastewater can be purified. Biochemical water treatment methods can be divided into activated sludge method, biofilm method, biological oxidation tower, land treatment system and anaerobic biological water treatment method.

Biochemical water treatment process:

Raw water → grid → regulating tank → contact oxidation tank → sedimentation area → filtration → disinfection → effluent.

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Knowledge of softening resin

Water treatment resin is divided into cationic resin and anionic resin. Cationic resin is subdivided into sodium type and hydrogen type. Sodium type resin exchanges calcium and magnesium ions in water into sodium ions to soften water. Hydrogen resin is used to exchange calcium and magnesium ions in water into hydrogen ions to soften water Anionic resin contains replaceable hydroxyl ions, which can replace acid ions in effluent. At the same time, anionic resin and hydrogen cationic resin can change water into purified water.

In the water treatment industry, ion exchange is the equal charge molar reaction between ions in water and ions on ion exchange resin.

Physical property

The particle size and related physical properties of ion exchange resin have a great influence on its work and performance.

Resin particle size

Ion exchange resins are usually made into bead shaped small particles, and its size is also important. When the resin particles are finer, the reaction speed is higher, but the fine particles have greater resistance to the passage of liquid and need higher working pressure; In particular, the viscosity of concentrated sugar solution is high, which has a more significant effect. Therefore, the size of resin particles should be selected appropriately. If the resin particle size is less than 0.2mm (about 70 mesh), it will significantly increase the resistance of fluid passage and reduce the flow and production capacity. The size of resin particles is usually measured by wet sieving method. The resin is sieved after full water absorption and expansion, and its retention on the 20, 30, 40, 50 mesh screen is accumulated. 90% of the particles can pass through the corresponding screen hole diameter, which is called the “effective particle size” of the resin. The effective particle size of most general resin products is between 0.4 ~ 0.6mm. Whether the resin particles are uniform is expressed by the uniformity coefficient. It is to measure the “effective particle size” of the resin, take the cumulative retention of 40% particles, and the ratio of the corresponding sieve diameter to the effective particle size. If the effective particle size of a resin (IR-120) is 0.4 ~ 0.6mm, and its retained particles on 20 mesh sieve, 30 mesh sieve and 40 mesh sieve are 18.3%, 41.1%, and 31.3% respectively, the calculated uniformity coefficient is 2.

Density of resin

The density of resin when dry is called true density. The weight of wet resin per unit volume (including the gap between particles) is called apparent density. The density of resin is related to its crosslinking degree and the properties of exchange groups. Generally, the density of resin with high crosslinking degree is higher, the density of strong acid or strong alkaline resin is higher than that of weak acid or weak alkali, while the density of macroporous resin is lower.

Solubility of resin

The ion exchange resin shall be insoluble. However, substances with low degree of polymerization mixed in the process of resin synthesis and substances generated by resin decomposition will be dissolved during operation. The resin with low crosslinking degree and more active groups has a greater dissolution tendency.

Expansion degree of resin

Ion exchange resin contains a large number of hydrophilic groups, which absorb water and expand when contacting with water. When the ions in the resin change, such as the cation resin from H + to Na +, and the anion resin from Cl – to OH -, they expand due to the increase of ion diameter and increase the volume of the resin. Generally, resins with low degree of crosslinking have a high degree of expansion. When designing the ion exchange device, the expansion degree of the resin must be considered to adapt to the resin volume change caused by the ion conversion in the resin during production and operation.

Durability of resin

The resin particles have changes such as transfer, friction, expansion and contraction during use, and there will be a small amount of loss and fragmentation after long-term use. Therefore, the resin should have high mechanical strength and wear resistance. Generally, the resin with low crosslinking degree is easy to break, but the durability of the resin mainly depends on the uniformity and strength of the crosslinking structure. The resin with high repeated crosslinking structure and high crosslinking resistance.

Cationic resin

This kind of resin contains a large number of strong acidic groups, such as sulfonate-so3h, which is easy to dissociate H + in solution, so it is strongly acidic After the resin dissociates, the negative groups contained in the body, such as SO3 -, can adsorb other cations in the binding solution These two reactions exchange H + in the resin with cations in the solution Strong acid resin has strong dissociation ability and can dissociate and produce ion exchange in acidic or alkaline solution After the resin is used for a period of time, regeneration treatment shall be carried out, that is, the ion exchange reaction shall be carried out in the opposite direction with chemicals to restore the functional groups of the resin to the original state for reuse For example, the above cationic resin is regenerated with strong acid. At this time, the resin releases the adsorbed cation and combines with H + to restore the original composition.


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How to choose a water purifier at home

Abstr: water purifier is used to purify water, and in order to ensure the safety of drinking water, many families will choose to be equipped with a water purifier, so how should they choose a water purifier?

1. The water softener mainly replaces calcium and magnesium ions in the effluent through resin substances to soften the water quality, reduce the hardness of the water, reduce the wear of minerals in the water on clothes and skin, and protect the skin and clothing materials. It can also avoid the formation of yellow spots caused by minerals in water in sanitary ware and tableware, and avoid the scale caused by water pipes and water heater showers.

2. As the core component of water purifier, filter element is very key, which directly affects the quality of effluent. Consumers should carefully read the instructions, pay attention to the parameters such as water purification flow, rated total water purification volume, applicable water pressure and main filtered substances, and then select the products with good brand and high cost performance in combination with the service life and sales price, considering the cost of replacing the filter element and other factors.

3. It should be noted that the influent must be municipal tap water. Only when the influent is municipal tap water can the effluent quality meet the requirements of the effluent quality in the health license approval document; At the same time, in the process of use, the filter element shall be replaced in time according to the service life of the filter element of the water purifier, so as to prevent the old filter element from exceeding the filter load during long-term use, resulting in secondary pollution of the effluent quality.

The following aspects are mainly considered:

1. See the qualification: consumers can check it on the public network of health administrative license when purchasing. The relevant data of a water purifier are all verified and recorded on the website. If you are not very confident about that standard, you can go online to find the data and compare it.


2. Look at the material: there are stainless steel, FRP, cast iron, aluminum, food grade resin or PVC and other materials on the market. The first three materials with good compression resistance can be used as pre filter (central machine). The latter two materials have poor compression resistance and can only be used at the back end of the pre filter (central machine) as a direct drinking machine. Stainless steel is the best and the price is relatively high.


3. Fixed function: when choosing a water processor, you should first clarify your purpose. First, from the big concept, whether to purify water or soften water. Purified water is to remove sediment, impurities, bacteria, heavy metals, residual chlorine, organic matter and some minerals. Softened water is the calcium and magnesium ions in the water, and the most direct is scale.


4. Filter material selection: at present, the commonly used water purification materials mainly include ppcotton, activated carbon, KDF, ultrafiltration membrane, RO membrane (reverse osmosis suitable membrane, reverse osmosis induced membrane), quartz sand, Maifan stone, infrared mineralized ball, etc. Different water purification materials will produce different purification effects. Consumers can choose a suitable water purifier according to their desired purification effect.


5. Ratio size: This is the most realistic way. Generally, the model of water purifier is determined according to the instantaneous water output. Those exceeding 20 tons / hour can be called central water purifier, and those less than 10 tons / hour can be called direct drinking water purifier. The water output is related to the volume and the diameter of the inlet and outlet. Usually, the larger the water purifier, the greater the instantaneous water output. More generally speaking, that is, the comparison of water output. Those with large water output must have higher efficiency in water purification.

Dechofilt is professional on supplying both industrial and civil water treatment equipment and parts.

if you need any for your project, pls contact us by e-mail [email protected]

Composition process of water treatment ultrafiltration system

1. Prefilter

A prefilter with certain filtration accuracy must be configured before the ultrafiltration system to prevent large particles from entering the ultrafiltration membrane module and blocking the membrane wire and filtration channel, or even causing scratch and damage to the membrane wire. The internal pressure ultrafiltration membrane is required to be equipped with a prefilter with a filtration accuracy of less than 150um. There are many options for the form of filter.

2. Pre dosing system

Before the ultrafiltration system, flocculant and bactericide can be added according to the specific water source. Generally speaking, the addition of flocculant contributes to the formation of filter cake layer on the membrane surface, prevents deep pollution on the membrane surface and micropores, and it is easy to clean pollutants out of the membrane system during backwashing; The dosing type and dosage are determined according to the parameters such as turbidity and pH of water source. The addition of bactericide can effectively prevent biological pollution and reduce organic pollution. At the same time, it can keep a certain amount of bactericide surplus in ultrafiltration water production, which can inhibit secondary pollution in pipelines and water tanks.

3. Backwashing system and production water tank

The ultrafiltration system must be equipped with a backwashing system to regularly remove the trapped pollutants and restore the filtration performance of the ultrafiltration membrane system. The backwashing system is composed of production water tank, backwashing pump, pipeline, valve and dosing system. The backwashing process is completed by automatic control program. Ultrafiltration backwashing is generally divided into water backwashing and dosing backwashing. Bactericide, acid and alkali can be added for dosing backwashing, and the optimized configuration can be selected according to the different water quality of water source. Backwashing dosing is one of the membrane performance recovery methods that must be used in ultrafiltration system. It can greatly prolong the cycle of shutdown chemical cleaning.

4. Chemical cleaning system

The chemical cleaning system is generally composed of cleaning water tank, cleaning pump, filter and mixing and heating equipment. When the ultrafiltration is seriously polluted or the membrane pressure difference has reached the specified limit, and the dosing backwashing can no longer restore the performance of the ultrafiltration system, shutdown chemical cleaning is required. The chemical cleaning system is generally controlled by manual valves.

Dechofilt is professional on supplying both industrial and civil water treatment equipment and parts.

if you need any for your project, pls contact us by e-mail [email protected]