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How does reverse osmosis work as a filter technology?

Reverse osmosis, also called hyperfiltration, is a widely used filter technology in the horticulture for the removal of salts, minerals, fertilizers and crop protection agents. The advantage of reverse osmosis is that this technology does not make us of chemicals, but uses filtering by means of a membrane. In this article, our specialists provide more information about reverse osmosis.
Joshua Reijnen
Technical specialist Water engineering | February 12, 2021 | 3 min. reading time

Osmosis

Osmosis is a natural process in which two liquids are mixed by use of a semi-permeable membrane. A semi-permeable membrane does let certain atoms and molecules through (like water molecules), but other (like salt molecules). In osmosis the polluted water flows through this semi-permeable membrane towards the liquid with the lower concentration. This is repeated until a balance is created in the percentage of dissolved substance on both sides of the membrane. This percentage will never be totally equal, because the water volume will increase on the side that the water flows towards. This ensures that the pressure on that side is increased. If that pressure is high enough to stop the water current that is coming through the membrane, then the process will cease. This pressure is called the osmotic pressure.
Reverse osmosis

Functioning of reverse osmosis

The operational principle of reverse osmosis is – as the name suggests – is opposite to that of osmosis. Here, the membrane is used as an extremely fine filter, that the dissolved substances can be filtered from the water with. By reversing the osmotic pressure and thus press the water through the membrane, under pressure, small water molecules are able to go through the membrane, but the larger molecules or chemical molecules are not. These will remain in the area in front of the membrane and are discharged from here as waste water. This makes reverse osmosis very suitable for the removal of crop protection agents and fertilizers from waste water. 

The pure water on the other side of the membrane can then be used again as irrigation water (but do note: this may not be discharged!). This water is called osmosis water.
Reversed osmosis

Cross flows

Reverse osmosis makes use of cross flows. This technology sees to it that the membrane rinses itself clean and does not get blocked. The liquid remaining in the area in front of the membrane, will flow past the membrane, so that the particles remaining in the membrane are eroded.

Remnant values

Purified osmosis water always contains minor remnant values. For most membranes a minimum value of 95 to 97% purified water applies (these are minimum test values; in practice, these values are usually higher). 
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How does reverse osmosis work as a filter technology?

Reverse osmosis, also called hyperfiltration, is a widely used filter technology in the horticulture for the removal of salts, minerals, fertilizers and crop protection agents. The advantage of reverse osmosis is that this technology does not make us of chemicals, but uses filtering by means of a membrane. In this article, our specialists provide more information about reverse osmosis.
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Joshua Reijnen
Joshua Reijnen
Technical specialist Water engineering | February 12, 2021 | 3 min. reading time
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Osmosis

Osmosis is a natural process in which two liquids are mixed by use of a semi-permeable membrane. A semi-permeable membrane does let certain atoms and molecules through (like water molecules), but other (like salt molecules). In osmosis the polluted water flows through this semi-permeable membrane towards the liquid with the lower concentration. This is repeated until a balance is created in the percentage of dissolved substance on both sides of the membrane. This percentage will never be totally equal, because the water volume will increase on the side that the water flows towards. This ensures that the pressure on that side is increased. If that pressure is high enough to stop the water current that is coming through the membrane, then the process will cease. This pressure is called the osmotic pressure.
Reverse osmosis

Functioning of reverse osmosis

The operational principle of reverse osmosis is – as the name suggests – is opposite to that of osmosis. Here, the membrane is used as an extremely fine filter, that the dissolved substances can be filtered from the water with. By reversing the osmotic pressure and thus press the water through the membrane, under pressure, small water molecules are able to go through the membrane, but the larger molecules or chemical molecules are not. These will remain in the area in front of the membrane and are discharged from here as waste water. This makes reverse osmosis very suitable for the removal of crop protection agents and fertilizers from waste water. 

The pure water on the other side of the membrane can then be used again as irrigation water (but do note: this may not be discharged!). This water is called osmosis water.
Reversed osmosis

Cross flows

Reverse osmosis makes use of cross flows. This technology sees to it that the membrane rinses itself clean and does not get blocked. The liquid remaining in the area in front of the membrane, will flow past the membrane, so that the particles remaining in the membrane are eroded.

Remnant values

Purified osmosis water always contains minor remnant values. For most membranes a minimum value of 95 to 97% purified water applies (these are minimum test values; in practice, these values are usually higher). 
Contact form
Can't find your answer? Fill out the contact form and our specialist Joshua Reijnen will get back to you. On weekdays, even within 24 hours.
Joshua Reijnen
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