Water treatment membrane:Nanofiltration membrane, reverse osmosis membrane, ultrafiltration membrane comparison
Nanofiltration Membrane: Capable of retaining nanoscale (0.001 micron) substances. The operating range of the nanofiltration membrane is between ultrafiltration and reverse osmosis, the molecular weight of the intercepted organic matter is about 200-800, the ability to intercept dissolved salts is between 20% and 98%, and the removal rate of soluble monovalent ions Lower than high-valent ions, nanofiltration is generally used to remove organic matter and pigments in surface water, hardness and radium in groundwater, and partially remove dissolved salts, and extract and concentrate useful substances in food and pharmaceutical production. The operating pressure of the nanofiltration membrane is generally 3.5-30bar.
Reverse osmosis membrane: It is the finest membrane separation product, which can effectively intercept all dissolved salts and organic substances with a molecular weight greater than 100, while allowing water molecules to pass through. Reverse osmosis membranes are widely used in seawater and brackish water desalination, boiler feed water, industrial pure water and electronic grade 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 dissolved solids (inorganic salts), while retaining colloids, proteins, microorganisms, and macromolecular organic substances. The operating pressure of the ultrafiltration membrane is generally 1-5bar.
The difference between ultrafiltration membrane and nanofiltration and reverse osmosis
Ultrafiltration membrane: Ultrafiltration membrane is a pressurized membrane separation technology, that is, under a certain pressure, small molecular solutes and solvents pass through a special membrane with a certain pore size, so that macromolecular solutes cannot pass through and remain in the membrane. One side, so that the macromolecular substances have been partially purified.
Nanofiltration: Nanofiltration is between ultrafiltration and reverse osmosis. Now it is mainly used for water plant or industrial desalination. The desalination rate is over 90%. The desalination rate of reverse osmosis is over 99%. However, if the water quality requirements are not particularly high, the use of nanofiltration can save a lot of cost.
Reverse osmosis: Reverse osmosis is a membrane separation and filtration technology powered by pressure gauge difference. It has been widely used in scientific research, medicine, food, beverage, seawater desalination and other fields. Used for the preparation of space water, pure water, distilled water, etc.; alcohol manufacturing and water reduction; pre-preparation of water for medicine, electronics and other industries; concentration, separation, purification and water distribution preparation of chemical processes; desalination and soft water for boiler feed water; seawater , Desalination of brackish water; water and wastewater treatment in papermaking, electroplating, printing and dyeing industries.
Comparison of the advantages and disadvantages of reverse osmosis membrane and ultrafiltration membrane
The pore size of the reverse osmosis membrane is only 1/100 of the size 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, while the ultrafiltration water purifier is powerless of. The particulate pollutants and bacteria that can be removed by ultrafiltration water purifiers can be removed by reverse osmosis.
The core components of reverse osmosis and ultrafiltration are membrane elements, and there are two main differences:
1. The water quality of the effluent is different from the testing standards of the health department. Let me give you an example to illustrate that the bacterial index of the effluent, the ultrafiltration according to the "general water quality processor", the total number of colonies is 100/ml; and the reverse osmosis water treatment equipment It is 20 per milliliter, and the requirements are stricter. Of course, the water quality of the reverse osmosis water treatment equipment is much better than that of ultrafiltration.
2. Reverse osmosis water treatment equipment is water supply by quality, pure water is supplied for drinking, and concentrated water is used for washing; while ultrafiltration is generally used as washing water; when the tap water quality is relatively high quality, it can also be used as ultra-pure water equipment for drinking water .
Advantages of ultrafiltration: generally no pumps, no power consumption, no electrical safety issues; few joints, low water pressure, relatively low failure rate and water leakage probability; simple structure, cheap price; easy operation, low cost, no need to add any chemical Reagents, especially ultrafiltration technology, have mild experimental conditions, no phase changes compared with evaporation and freeze-drying, and do not cause changes in temperature and pH, thus preventing denaturation, inactivation and autolysis of biomacromolecules. In the preparation technology of biomacromolecules, ultrafiltration is mainly used for desalination, dehydration and concentration of biomacromolecules.
The advantages of reverse osmosis water treatment equipment: the water quality is safe and can effectively remove various harmful impurities in the water quality; the effect is better for water supply incidents; the taste of the water is better; it can effectively reduce the hardness of the water quality, and the boiling water container is not easy to scale
Application of different membranes in water treatment
Nanofiltration membrane is used for drinking water preparation and deep purification, application in wastewater treatment A, domestic sewage B, textile, printing and dyeing wastewater C, tanning wastewater D, electroplating wastewater E, papermaking wastewater.
Forward osmosis (FO) applications: seawater desalination, industrial wastewater treatment, landfill leachate treatment
Reverse osmosis membrane: routine application of water purification, application of urban sewage, application of heavy metal wastewater treatment, application of oily wastewater, etc.
Nanofiltration membrane, reverse osmosis membrane, ultrafiltration membrane comparison
Nanofiltration Membrane: Capable of retaining nanoscale (0.001 micron) substances. The operating range of the nanofiltration membrane is between ultrafiltration and reverse osmosis, the molecular weight of the intercepted organic matter is about 200-800, the ability to intercept dissolved salts is between 20% and 98%, and the removal rate of soluble monovalent ions Lower than high-valent ions, nanofiltration is generally used to remove organic matter and pigments in surface water, hardness and radium in groundwater, and partially remove dissolved salts, and extract and concentrate useful substances in food and pharmaceutical production. The operating pressure of the nanofiltration membrane is generally 3.5-30bar.
Reverse osmosis membrane: It is the finest membrane separation product, which can effectively intercept all dissolved salts and organic substances with a molecular weight greater than 100, while allowing water molecules to pass through. Reverse osmosis membranes are widely used in seawater and brackish water desalination, boiler feed water, industrial pure water and electronic grade 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 dissolved solids (inorganic salts), while retaining colloids, proteins, microorganisms, and macromolecular organic substances. The operating pressure of the ultrafiltration membrane is generally 1-5bar.
The difference between ultrafiltration membrane and nanofiltration and reverse osmosis
Ultrafiltration membrane: Ultrafiltration membrane is a pressurized membrane separation technology, that is, under a certain pressure, small molecular solutes and solvents pass through a special membrane with a certain pore size, so that macromolecular solutes cannot pass through and remain in the membrane. One side, so that the macromolecular substances have been partially purified.
Nanofiltration: Nanofiltration is between ultrafiltration and reverse osmosis. Now it is mainly used for water plant or industrial desalination. The desalination rate is over 90%. The desalination rate of reverse osmosis is over 99%. However, if the water quality requirements are not particularly high, the use of nanofiltration can save a lot of cost.
Reverse osmosis: Reverse osmosis is a membrane separation and filtration technology powered by pressure gauge difference. It has been widely used in scientific research, medicine, food, beverage, seawater desalination and other fields. Used for the preparation of space water, pure water, distilled water, etc.; alcohol manufacturing and water reduction; pre-preparation of water for medicine, electronics and other industries; concentration, separation, purification and water distribution preparation of chemical processes; desalination and soft water for boiler feed water; seawater , Desalination of brackish water; water and wastewater treatment in papermaking, electroplating, printing and dyeing industries.
Comparison of advantages and disadvantages between reverse osmosis membrane and ultrafiltration membrane
The pore size of the reverse osmosis membrane is only 1/100 of the size 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, while the ultrafiltration water purifier is powerless of. The particulate pollutants and bacteria that can be removed by ultrafiltration water purifiers can be removed by reverse osmosis.
The core components of reverse osmosis and ultrafiltration are membrane elements, and there are two main differences:
1. The water quality of the effluent is different from the testing standards of the health department. Let me give you an example to illustrate that the bacterial index of the effluent, the ultrafiltration according to the "general water quality processor", the total number of colonies is 100/ml; and the reverse osmosis water treatment equipment It is 20 per milliliter, and the requirements are stricter. Of course, the water quality of the reverse osmosis water treatment equipment is much better than that of ultrafiltration.
2. Reverse osmosis water treatment equipment is water supply by quality, pure water is supplied for drinking, and concentrated water is used for washing; while ultrafiltration is generally used as washing water; when the tap water quality is relatively high quality, it can also be used as ultra-pure water equipment for drinking water .
Advantages of ultrafiltration: generally no pumps, no power consumption, no electrical safety issues; few joints, low water pressure, relatively low failure rate and water leakage probability; simple structure, cheap price; easy operation, low cost, no need to add any chemical Reagents, especially ultrafiltration technology, have mild experimental conditions, no phase changes compared with evaporation and freeze-drying, and do not cause changes in temperature and pH, thus preventing denaturation, inactivation and autolysis of biomacromolecules. In the preparation technology of biomacromolecules, ultrafiltration is mainly used for desalination, dehydration and concentration of biomacromolecules.
The advantages of reverse osmosis water treatment equipment: the water quality is safe and can effectively remove various harmful impurities in the water quality; the effect is better for water supply incidents; the taste of the water is better; it can effectively reduce the hardness of the water quality, and the boiling water container is not easy to scale
Application of different membranes in water treatment
Nanofiltration membrane is used for drinking water preparation and deep purification, application in wastewater treatment A, domestic sewage B, textile, printing and dyeing wastewater C, tanning wastewater D, electroplating wastewater E, papermaking wastewater.
Forward osmosis (FO) applications: seawater desalination, industrial wastewater treatment, landfill leachate treatment
Reverse osmosis membrane: routine application of water purification, application of urban sewage, application of heavy metal wastewater treatment, application of oily wastewater, etc.
