Comparison of nanofiltration membrane, reverse osmosis membrane and ultrafiltration membrane

Nanofiltration membrane: capable of intercepting substances of nanometer scale (0.001 μ m). The operating range of nanofiltration membrane is between ultrafiltration and reverse osmosis. Its molecular weight of organic matter is about 200-800, and its ability to retain dissolved salts is between 20% and 98%. The removal rate of soluble monovalent ions is lower than that of high-valent ions. Nanofiltration is generally used to remove organic substances and pigments in surface water, hardness and radium in groundwater, and partially remove dissolved salts. It is used to extract and concentrate useful substances in food and medicine production. The operating pressure of nanofiltration membrane is generally 3.5-30bar.

Reverse osmosis membrane: It is the most refined membrane separation product, which can effectively intercept all dissolved salts and organic substances with molecular weight greater than 100, and allow water molecules to pass through. Reverse osmosis membrane is widely used in seawater and brackish water desalination, boiler make-up water, industrial pure water and electronic high purity water preparation, drinking pure water production, wastewater treatment and special separation processes.

Ultrafiltration membrane: it can intercept macromolecular substances and proteins between 1-20nm. The ultrafiltration membrane allows the passage of small molecular substances and soluble solids (inorganic salts), and will retain colloid, protein, microorganism and macromolecular organic matter. The operating pressure of the ultrafiltration membrane is generally 1-5bar.

Ultrafiltration membrane and difference between nanofiltration and reverse osmosis

Ultrafiltration membrane: Ultrafiltration membrane is a kind of pressurized membrane separation technology, that is, under a certain pressure, make small molecular solute and solvent pass through a special membrane with a certain aperture, but make macromolecular solute cannot pass through, and stay on one side of the membrane, so that macromolecular substances are partially purified.

Nanofiltration: nanofiltration, between ultrafiltration and reverse osmosis. Now it is mainly used for water plants or industrial desalination. The desalting rate is more than 90%. The desalination rate of reverse osmosis is more than 99%, but if the requirements for water quality are not particularly high, the use of nanofiltration can save a lot of costs.

Reverse osmosis: reverse osmosis is a membrane separation and filtration technology powered by pressure gauge difference, which has been widely used in scientific research, medicine, food, beverage, seawater desalination and other fields. Used for preparation of space water, purified water, distilled water, etc; Water for alcohol manufacturing and degreasing; Pre-preparation of water for medicine, electronics and other industries; Concentration, separation, purification and water preparation of chemical process; Demineralized soft water for boiler make-up water; Desalination of seawater and brackish water; Water and wastewater treatment in papermaking, electroplating, printing and dyeing industries.

Comparison of advantages and disadvantages of reverse osmosis membrane and ultrafiltration membrane

The pore size of the reverse osmosis membrane is only 1/100 of that of the ultrafiltration membrane, so the reverse osmosis water treatment equipment can effectively remove heavy metals, pesticides, chloroform and other chemical pollutants in the water quality, and the ultrafiltration water purifier can't do anything about it. The particle pollutants and bacteria that can be removed by ultrafiltration water purifier can be completely removed by reverse osmosis.

The core components of reverse osmosis and ultrafiltration are membrane elements, with two main differences:

1. The effluent quality is different from the detection standard of the health department. Let me give you an example to illustrate that the effluent bacterial index, ultrafiltration according to the "general water quality processor", the total number of bacterial colonies is 100/ml; The reverse osmosis water treatment equipment is 20 pieces/ml, which is relatively strict. Of course, the water quality of the reverse osmosis water treatment equipment is also much better than ultrafiltration.

2. The reverse osmosis water treatment equipment supplies water by quality, pure water for drinking, and concentrated water for washing; Ultrafiltration is generally used as washing water; When the water quality of tap water is relatively high, it can also be used as ultra-pure drinking water equipment.

Advantages of ultrafiltration: generally no pump, no power consumption, no electrical safety problems; Few joints, low water pressure, relatively low failure rate and water leakage probability; Simple structure and low price; The operation is simple, the cost is low, and there is no need to add any chemical reagent. Especially, the experimental conditions of ultrafiltration technology are mild. Compared with evaporation and freeze-drying, there is no phase change, and it does not cause changes in temperature and pH, so it can prevent the denaturation, inactivation and autolysis of biological macromolecules. In the preparation technology of biological macromolecules, ultrafiltration is mainly used for desalting, dehydration and concentration of biological macromolecules.

Advantages of reverse osmosis water treatment equipment: water quality is safe and can effectively remove various harmful impurities in water quality; The effect is good for water supply emergencies; The taste of effluent is good; It can effectively reduce the hardness of water quality, and the boiling water container is not easy to scale

Application of different membranes in water treatment

Nanofiltration membrane is the preparation and deep purification of drinking water, application in wastewater treatment A, domestic sewage B, textile, printing and dyeing wastewater C, tannery wastewater D, electroplating wastewater E, papermaking wastewater.

Application of forward osmosis (FO): seawater desalination, industrial wastewater treatment, landfill leachate treatment

Reverse osmosis membrane: conventional application of water purification, application of urban sewage, application of heavy metal wastewater treatment, application of oily wastewater, etc.

Comparison of nanofiltration membrane, reverse osmosis membrane and ultrafiltration membrane

Nanofiltration membrane: capable of intercepting substances of nanometer scale (0.001 μ m). The operating range of nanofiltration membrane is between ultrafiltration and reverse osmosis. Its molecular weight of organic matter is about 200-800, and its ability to retain dissolved salts is between 20% and 98%. The removal rate of soluble monovalent ions is lower than that of high-valent ions. Nanofiltration is generally used to remove organic substances and pigments in surface water, hardness and radium in groundwater, and partially remove dissolved salts. It is used to extract and concentrate useful substances in food and medicine production. The operating pressure of nanofiltration membrane is generally 3.5-30bar.

Reverse osmosis membrane: It is the most refined membrane separation product, which can effectively intercept all dissolved salts and organic substances with molecular weight greater than 100, and allow water molecules to pass through. Reverse osmosis membrane is widely used in seawater and brackish water desalination, boiler make-up water, industrial pure water and electronic high purity water preparation, drinking pure water production, wastewater treatment and special separation processes.

Ultrafiltration membrane: it can intercept macromolecular substances and proteins between 1-20nm. The ultrafiltration membrane allows the passage of small molecular substances and soluble solids (inorganic salts), and will retain colloid, protein, microorganism and macromolecular organic matter. The operating pressure of the ultrafiltration membrane is generally 1-5bar.

Ultrafiltration membrane and difference between nanofiltration and reverse osmosis

Ultrafiltration membrane: Ultrafiltration membrane is a kind of pressurized membrane separation technology, that is, under a certain pressure, make small molecular solute and solvent pass through a special membrane with a certain aperture, but make macromolecular solute cannot pass through, and stay on one side of the membrane, so that macromolecular substances are partially purified.

Nanofiltration: nanofiltration, between ultrafiltration and reverse osmosis. Now it is mainly used for water plants or industrial desalination. The desalting rate is more than 90%. The desalination rate of reverse osmosis is more than 99%, but if the requirements for water quality are not particularly high, the use of nanofiltration can save a lot of costs.

Reverse osmosis: reverse osmosis is a membrane separation and filtration technology powered by pressure gauge difference, which has been widely used in scientific research, medicine, food, beverage, seawater desalination and other fields. Used for preparation of space water, purified water, distilled water, etc; Water for alcohol manufacturing and degreasing; Pre-preparation of water for medicine, electronics and other industries; Concentration, separation, purification and water preparation of chemical process; Demineralized soft water for boiler make-up water; Desalination of seawater and brackish water; Water and wastewater treatment in papermaking, electroplating, printing and dyeing industries.

Comparison of advantages and disadvantages of reverse osmosis membrane and ultrafiltration membrane

The pore size of the reverse osmosis membrane is only 1/100 of that of the ultrafiltration membrane, so the reverse osmosis water treatment equipment can effectively remove heavy metals, pesticides, chloroform and other chemical pollutants in the water quality, and the ultrafiltration water purifier can't do anything about it. The particle pollutants and bacteria that can be removed by ultrafiltration water purifier can be completely removed by reverse osmosis.

The core components of reverse osmosis and ultrafiltration are membrane elements, with two main differences:

1. The effluent quality is different from the detection standard of the health department. Let me give you an example to illustrate that the effluent bacterial index, ultrafiltration according to the "general water quality processor", the total number of bacterial colonies is 100/ml; The reverse osmosis water treatment equipment is 20 pieces/ml, which is relatively strict. Of course, the water quality of the reverse osmosis water treatment equipment is also much better than ultrafiltration.

2. The reverse osmosis water treatment equipment supplies water by quality, pure water for drinking, and concentrated water for washing; Ultrafiltration is generally used as washing water; When the water quality of tap water is relatively high, it can also be used as ultra-pure drinking water equipment.

Advantages of ultrafiltration: generally no pump, no power consumption, no electrical safety problems; Few joints, low water pressure, relatively low failure rate and water leakage probability; Simple structure and low price; The operation is simple, the cost is low, and there is no need to add any chemical reagent. Especially, the experimental conditions of ultrafiltration technology are mild. Compared with evaporation and freeze-drying, there is no phase change, and it does not cause changes in temperature and pH, so it can prevent the denaturation, inactivation and autolysis of biological macromolecules. In the preparation technology of biological macromolecules, ultrafiltration is mainly used for desalting, dehydration and concentration of biological macromolecules.

Advantages of reverse osmosis water treatment equipment: water quality is safe and can effectively remove various harmful impurities in water quality; The effect is good for water supply emergencies; The taste of effluent is good; It can effectively reduce the hardness of water quality, and the boiling water container is not easy to scale

Application of different membranes in water treatment

Nanofiltration membrane is the preparation and deep purification of drinking water, application in wastewater treatment A, domestic sewage B, textile, printing and dyeing wastewater C, tannery wastewater D, electroplating wastewater E, papermaking wastewater.

Application of forward osmosis (FO): seawater desalination, industrial wastewater treatment, landfill leachate treatment

Reverse osmosis membrane: conventional application of water purification, application of urban sewage, application of heavy metal wastewater treatment, application of oily wastewater, etc