12 Dec 2024
Why should antiscalant be added to reverse osmosis equipment?
Reverse osmosis water treatment equipment passes raw water through precision filters, granular activated carbon filters, compressed activated carbon filters, etc., and then pressurizes it through a pump. It uses a reverse osmosis membrane (RO membrane) with a pore size of 1/10000μm (equivalent to 1/6000 of the size of E. coli and 1/300 of the size of a virus) to convert high-concentration water into low-concentration water. At the same time, all impurities such as industrial pollutants, heavy metals, bacteria, viruses, etc. that are mixed into the water are completely isolated. The water treatment equipment thus meets the physical and chemical indicators and hygiene standards required for drinking, and produces the clearest and purest water, which is the best choice for the human body to replenish high-quality water in a timely manner. Because the water produced by RO reverse osmosis technology has the highest purity among all water production technologies currently mastered by humans, the cleanliness is almost 100%.
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The reverse osmosis membrane is the key equipment of the reverse osmosis system. When the system is running continuously for a long time, calcium and magnesium ions in the water will continue to precipitate and attach to the surface of the reverse osmosis membrane, forming scale to block the membrane pores, which will affect the water output efficiency of the reverse osmosis system and damage the reverse osmosis membrane. Since the reverse osmosis membrane is relatively expensive, a dosing system should be added during the operation of the system. The water treatment equipment adds reverse osmosis scale inhibitors to the water to delay the precipitation of calcium and magnesium ions and scaling on the membrane surface.
Aitel reverse osmosis scale inhibitor is a scale inhibitor specially used for reverse osmosis (RO) systems and nanofiltration (NF) and ultrafiltration (UF) systems. It can prevent scaling on the membrane surface, increase water production and quality, and reduce operating costs.
Features:
① Effectively control inorganic scaling in a wide concentration range
② Does not condense with iron, aluminum oxides and silicon compounds to form insoluble substances
③ Effectively inhibit silicon polymerization and deposition, SiO2 concentration on the concentrated water side can reach 290 ppm
④ Can be used for reverse osmosis CA and TFC membranes, nanofiltration membranes and ultrafiltration membranes
⑤ Excellent solubility and stability
⑥ Effective in the range of 5-10 pH value of feed water
Basic functions of reverse osmosis scale inhibitors:
① Complexation and solubilization: After reverse osmosis scale inhibitors are dissolved in water, they are ionized to generate negatively charged molecular chains, which form water-soluble complexes or chelates with Ca2, thereby increasing the solubility of inorganic salts and playing a scale inhibition role.
② Lattice distortion: Some functional groups in the molecules of reverse osmosis scale inhibitors occupy a certain position on the inorganic salt nucleus or microcrystals, hindering and destroying the normal growth of inorganic salt crystals, slowing down the growth rate of crystals, and thus reducing the formation of salt scale;
③ Electrostatic repulsion: After reverse osmosis scale inhibitors are dissolved in water, they are adsorbed on the microcrystals of inorganic salts, increasing the repulsion between particles, hindering their aggregation, and putting them in a good dispersed state, thereby preventing or reducing the formation of scale.
④ Functional types and applications of reverse osmosis scale inhibitors Reverse osmosis scale inhibitors are used to improve the performance of reverse osmosis and nanofiltration systems
⑤ Scale inhibitors and dispersants are a series of chemical agents used to prevent the precipitation and scaling of crystalline mineral salts.
Functions of scale inhibitors
1. Inhibition of precipitation function: In the system with scale inhibitors, the ion product value of the anions and cations of the easy structural components and the anions when they begin to precipitate is much larger than the critical precipitation ion product value when there is no scale inhibitor.
2. Dispersion function: When there is a scale inhibitor, the precipitated particles are small and difficult to condense, which is more difficult to settle than the precipitated particles without scale inhibitors.
3. Lattice deformation effect: In the system with scale inhibitors, the crystals precipitated
are amorphous states such as spheres, polyhedrons, and snowflakes. It is generally believed that amorphous crystals are crystals that grow in a different shape from the original shape of the crystal when the scale inhibitor is adsorbed on the crystal growth point during the crystal growth process.
4. Low limit effect: The dosage of scale inhibitor is equivalent to a much lower scaling component in the water, and it can also show the scale inhibition effect.
Application of RO scale inhibitors
1. Be especially careful when using polyacrylic acid scale inhibitors. When the iron content is high, it may cause membrane fouling. This fouling will increase the operating pressure of the membrane. Acid washing is required to effectively remove this type of fouling.
2. If cationic coagulants or filter aids are used in pretreatment, be especially careful when using anionic scale inhibitors. A viscous, sticky contaminant will be produced. The contamination will increase the operating pressure and is very difficult to clean.
3. Antiscalants hinder the growth of salt crystals in RO feed water and concentrate, thus allowing sparingly soluble salts to exceed saturated solubility in concentrate. Antiscalants can be used instead of acid addition or in combination with acid addition. There are many factors that affect the formation of mineral scale. Lowering temperature will reduce the solubility of scaling minerals, except for calcium carbonate, which is contrary to most substances. Its solubility decreases with increasing temperature. Increasing TDS will increase the solubility of sparingly soluble salts. This is because high ionic strength interferes with the formation of crystal seeds.
4. The ideal addition amount and the maximum saturation of scaling substances and pollutants are best determined by a dedicated software package provided by the chemical supplier. Excessive addition of antiscalants/dispersants will cause deposits to form on the membrane surface, causing new pollution problems. When the equipment is shut down, the antiscalants and dispersants must be thoroughly rinsed out, otherwise they will remain on the membrane and cause pollution problems. Stop injecting antiscalants and dispersants into the system when low-pressure flushing with RO feed water.
5. The design of the antiscalant/dispersant injection system should ensure that the reverse osmosis element can be fully mixed before the static mixer is a very effective mixing method. Most systems have injection points before the RO inlet safety filter. The buffering time in the filter and the stirring action of the RO inlet pump promote mixing. If the system uses acid addition to adjust pH, it is recommended that the acid addition point be far enough upstream to completely mix before reaching the antiscalant/dispersant injection point.
6. The dosing pump for injecting antiscalant/dispersant should be adjusted to the highest injection rate. The recommended injection rate is at least once every 5 seconds. The typical addition amount of antiscalant/dispersant is 2-5ppm. In order to make the dosing pump work at the highest frequency, the agent needs to be diluted. Antiscalant/dispersant products are concentrated liquids and solid powders. The extent to which diluted antiscalant/dispersant will be contaminated by biological contamination in the storage tank depends on the room temperature and the dilution multiple. The recommended retention time of the diluted liquid is about 7-10 days. Under normal circumstances, undiluted antiscalant/dispersant will not be bio-contaminated. Another major issue in selecting antiscalant/dispersant is to ensure full compatibility with the reverse osmosis membrane. Incompatible agents will cause irreversible damage to the membrane.
If you want to know more details about reverse osmosis equipment, please contact me!
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The reverse osmosis membrane is the key equipment of the reverse osmosis system. When the system is running continuously for a long time, calcium and magnesium ions in the water will continue to precipitate and attach to the surface of the reverse osmosis membrane, forming scale to block the membrane pores, which will affect the water output efficiency of the reverse osmosis system and damage the reverse osmosis membrane. Since the reverse osmosis membrane is relatively expensive, a dosing system should be added during the operation of the system. The water treatment equipment adds reverse osmosis scale inhibitors to the water to delay the precipitation of calcium and magnesium ions and scaling on the membrane surface.
Aitel reverse osmosis scale inhibitor is a scale inhibitor specially used for reverse osmosis (RO) systems and nanofiltration (NF) and ultrafiltration (UF) systems. It can prevent scaling on the membrane surface, increase water production and quality, and reduce operating costs.
Features:
① Effectively control inorganic scaling in a wide concentration range
② Does not condense with iron, aluminum oxides and silicon compounds to form insoluble substances
③ Effectively inhibit silicon polymerization and deposition, SiO2 concentration on the concentrated water side can reach 290 ppm
④ Can be used for reverse osmosis CA and TFC membranes, nanofiltration membranes and ultrafiltration membranes
⑤ Excellent solubility and stability
⑥ Effective in the range of 5-10 pH value of feed water
Basic functions of reverse osmosis scale inhibitors:
① Complexation and solubilization: After reverse osmosis scale inhibitors are dissolved in water, they are ionized to generate negatively charged molecular chains, which form water-soluble complexes or chelates with Ca2, thereby increasing the solubility of inorganic salts and playing a scale inhibition role.
② Lattice distortion: Some functional groups in the molecules of reverse osmosis scale inhibitors occupy a certain position on the inorganic salt nucleus or microcrystals, hindering and destroying the normal growth of inorganic salt crystals, slowing down the growth rate of crystals, and thus reducing the formation of salt scale;
③ Electrostatic repulsion: After reverse osmosis scale inhibitors are dissolved in water, they are adsorbed on the microcrystals of inorganic salts, increasing the repulsion between particles, hindering their aggregation, and putting them in a good dispersed state, thereby preventing or reducing the formation of scale.
④ Functional types and applications of reverse osmosis scale inhibitors Reverse osmosis scale inhibitors are used to improve the performance of reverse osmosis and nanofiltration systems
⑤ Scale inhibitors and dispersants are a series of chemical agents used to prevent the precipitation and scaling of crystalline mineral salts.
Functions of scale inhibitors
1. Inhibition of precipitation function: In the system with scale inhibitors, the ion product value of the anions and cations of the easy structural components and the anions when they begin to precipitate is much larger than the critical precipitation ion product value when there is no scale inhibitor.
2. Dispersion function: When there is a scale inhibitor, the precipitated particles are small and difficult to condense, which is more difficult to settle than the precipitated particles without scale inhibitors.
3. Lattice deformation effect: In the system with scale inhibitors, the crystals precipitated
are amorphous states such as spheres, polyhedrons, and snowflakes. It is generally believed that amorphous crystals are crystals that grow in a different shape from the original shape of the crystal when the scale inhibitor is adsorbed on the crystal growth point during the crystal growth process.
4. Low limit effect: The dosage of scale inhibitor is equivalent to a much lower scaling component in the water, and it can also show the scale inhibition effect.
Application of RO scale inhibitors
1. Be especially careful when using polyacrylic acid scale inhibitors. When the iron content is high, it may cause membrane fouling. This fouling will increase the operating pressure of the membrane. Acid washing is required to effectively remove this type of fouling.
2. If cationic coagulants or filter aids are used in pretreatment, be especially careful when using anionic scale inhibitors. A viscous, sticky contaminant will be produced. The contamination will increase the operating pressure and is very difficult to clean.
3. Antiscalants hinder the growth of salt crystals in RO feed water and concentrate, thus allowing sparingly soluble salts to exceed saturated solubility in concentrate. Antiscalants can be used instead of acid addition or in combination with acid addition. There are many factors that affect the formation of mineral scale. Lowering temperature will reduce the solubility of scaling minerals, except for calcium carbonate, which is contrary to most substances. Its solubility decreases with increasing temperature. Increasing TDS will increase the solubility of sparingly soluble salts. This is because high ionic strength interferes with the formation of crystal seeds.
4. The ideal addition amount and the maximum saturation of scaling substances and pollutants are best determined by a dedicated software package provided by the chemical supplier. Excessive addition of antiscalants/dispersants will cause deposits to form on the membrane surface, causing new pollution problems. When the equipment is shut down, the antiscalants and dispersants must be thoroughly rinsed out, otherwise they will remain on the membrane and cause pollution problems. Stop injecting antiscalants and dispersants into the system when low-pressure flushing with RO feed water.
5. The design of the antiscalant/dispersant injection system should ensure that the reverse osmosis element can be fully mixed before the static mixer is a very effective mixing method. Most systems have injection points before the RO inlet safety filter. The buffering time in the filter and the stirring action of the RO inlet pump promote mixing. If the system uses acid addition to adjust pH, it is recommended that the acid addition point be far enough upstream to completely mix before reaching the antiscalant/dispersant injection point.
6. The dosing pump for injecting antiscalant/dispersant should be adjusted to the highest injection rate. The recommended injection rate is at least once every 5 seconds. The typical addition amount of antiscalant/dispersant is 2-5ppm. In order to make the dosing pump work at the highest frequency, the agent needs to be diluted. Antiscalant/dispersant products are concentrated liquids and solid powders. The extent to which diluted antiscalant/dispersant will be contaminated by biological contamination in the storage tank depends on the room temperature and the dilution multiple. The recommended retention time of the diluted liquid is about 7-10 days. Under normal circumstances, undiluted antiscalant/dispersant will not be bio-contaminated. Another major issue in selecting antiscalant/dispersant is to ensure full compatibility with the reverse osmosis membrane. Incompatible agents will cause irreversible damage to the membrane.
If you want to know more details about reverse osmosis equipment, please contact me!