The working principle and advantages of reverse osmosis water treatment

Permeation technology is the most advanced and energy efficient membrane separation technology available today. The principle is that under the action of higher than the osmotic pressure of the solution, these substances and water are separated according to the fact that other substances cannot pass through the semi-permeable membrane. Since the pore size of the reverse osmosis membrane is very small (only about 10A), it can effectively remove dissolved salts, colloids, microorganisms, organic matter, etc. in the water (the removal rate is as high as 97-98%). The system has the advantages of good water quality, low energy consumption, no pollution, simple process and easy operation.

Reverse osmosis technology is usually used for fresh water of sea water and brackish water; softening treatment of water; wastewater treatment and purification, concentration and separation of food, pharmaceutical industry and chemical industry. In addition, the application of reverse osmosis technology to pre-salting treatment has also achieved good results, which can reduce the load of ion exchange resin by more than 90%, and the amount of regenerant of resin can also be reduced by 90%. Therefore, not only cost savings, but also environmental protection. Reverse osmosis technology can also be used to remove particles, organic substances and colloids in water, which has a good effect on reducing the pollution of ion exchange resin and prolonging the service life.

Reverse osmosis is the most widely used desalination technology in the preparation of high-purity water. MF) and electrodialysis (ED) technologies are both membrane separation technologies. In the past 30 years, reverse osmosis, electrodialysis, ultrafiltration and membrane filtration have entered industrial applications and developed rapidly. In semiconductor, integrated circuit manufacturing processes, food, and pharmaceutical industries, reverse osmosis is usually used as desalination in the preparation of high-purity water. Ultrafiltration is mostly used as post-treatment of water production systems, while membrane filtration is used for pre-treatment and post-treatment of water treatment to filter particles and bacteria.

working principle:

The system salt removal rate of reverse osmosis equipment is generally 98-99%. This salt removal rate can meet the requirements in most cases. In the electronics industry, ultra-high pressure boiler make-up water, and individual pharmaceutical industries for pure water requirements Possibly higher. At this time, the single-stage reverse osmosis equipment cannot meet the requirements.

Osmosis is common in nature. For example, when a cucumber is placed in salt water, the cucumber will become smaller due to water loss. The process by which the water molecules in the cucumber enter the brine solution is the osmosis process. If a pool is divided into two parts with a membrane that only water molecules can pass through, pure water and salt water are injected to the same height on both sides of the membrane. After a period of time, it can be found that the level of pure water decreases, while the level of salt water increases. We call the phenomenon of water molecules migrating into the brine through this membrane as osmosis. The rise of the salt water level is not endless, and it will reach an equilibrium point at a certain height. At this time, the pressure represented by the liquid level difference at both ends of the diaphragm is called osmotic pressure. The magnitude of osmotic pressure is directly related to the concentration of saline.

After the above device reaches equilibrium, if a certain pressure is exerted on the liquid surface of the brine end, the water molecules will migrate from the brine end to the pure water end. The phenomenon that liquid agent molecules migrate from dilute solution to concentrated solution under the action of pressure is called reverse osmosis phenomenon. If brine is added to one end of the above facility and a pressure is applied at that end that exceeds the osmotic pressure of that brine, we can get pure water at the other end. This is the principle of reverse osmosis water purification. There are two keys to the production of pure water in reverse osmosis facilities, one is a selective membrane, which we call a semi-permeable membrane, and the other is a certain pressure. Simply put, there are numerous pores on the reverse osmosis semipermeable membrane, and the size of these pores is comparable to the size of water molecules. Since bacteria, viruses, most organic pollutants and hydrated ions are much larger than water molecules, they cannot penetrate. It is separated from the water phase passing through the reverse osmosis membrane through the reverse osmosis semi-permeable membrane. Among the many impurities in water, soluble salts are the most difficult to remove. Therefore, the water purification effect of reverse osmosis is often determined according to the salt removal rate. The salt removal rate of reverse osmosis is mainly determined by the reverse osmosis semipermeable membrane. of selectivity. At present, the salt removal rate of highly selective reverse osmosis membrane elements can be as high as 99.7%.

Advantages of reverse osmosis:

  • Continuous operation, stable product water quality
  • No need for acid-base regeneration
  • No downtime due to regeneration
  • Saves water for backflushing and cleaning
  • Produces ultrapure water in high yield (up to 95% yield)
  • No recycled sewage, no need for sewage treatment facilities
  • No need for acid-base storage and acid-base dilution delivery facilities
  • Reduce workshop floor area
  • Safe and reliable use, avoid workers’ contact with acid and alkali
  • Reduce operating and maintenance costs
  • Simple installation and low installation cost

Xi’an CHIWATEC Water Treatment Technology is a high-tech enterprise specialized in various water processing devices. Aside from these individual products, which cover a number of types and series, we can also help with related comprehensive engineering projects. Thanks to our hard work and dedication upon our founding, we are now one of the fastest-developing water treatment equipment manufacturers in Western China.

Further reading:

Underground Reverse Osmosis Plant

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