Reverse osmosis
The reverse osmosis or reverse osmosis is a physical process for the concentration of dissolved substances in liquids, the pressure inversely with the natural osmosis process.
Working principle:
The medium in which the concentration of a particular substance is to be reduced is through a semi-permeable (semipermeable) membrane separated from the medium in which the concentration should be increased. This is exposed to a pressure that must be higher than the pressure created by the osmotic concentration of the request for compensation. This allows the molecules of the solvent against their "natural" osmotic propagation direction in the area, hiking in the already concentrated the solutes are lower.
Drinking bar has an osmotic pressure of less than 2, the applied pressure for the reverse osmosis drinking water is 3 to 30 bar, depending on the membrane and system configuration. For seawater desalination is a print from 60 to 80 bar required because sea water bar with about 30 exhibits a much higher osmotic pressure than water. The Dead Sea is actually an osmotic pressure bar front of 350. In some applications, eg for the concentration of landfill leachate, are still used higher pressures.
The osmotic membrane that allows only the carrier liquid (solvent) and dissolved substances (solutes) holds back, must withstand these high pressures. If the pressure difference, the osmotic gradient more than compensates for the solvent molecules fit like a filter through the membrane, while the "impurity" molecules are retained. Unlike a conventional membrane filter osmosis membranes have non-through pores. Rather, the ions and molecules through the membrane wander through it, by diffusing through the membrane material. The solution-diffusion model describes this process.
The osmotic pressure increases with increasing concentration difference. If the osmotic pressure equal to the applied pressure, the process comes to a halt. It is then in an osmotic balance. A steady flow of the concentrate can prevent this. Concentrate outlet when the pressure is controlled either via a pressure regulator or a pressure exchanger used to build the required pressure in the inlet of the system. Pressure Exchanger energy recovery by reducing the operating costs very effectively a reverse osmosis plant. The energy consumption per cubic meter of water is 4 to 9 kWh.
The crystallization (precipitation) of the solutes must be prevented in the membranes. This can be through the addition of anti-scaling agents (English Antiscaling) or acids can be achieved. Anti-deposition agents are here to polymeric compounds or phosphate Maleinsäurebasis enclosing the forming crystallites and thus prevent crystal precipitation may occur on the membrane. A cleaning of the membrane may still be necessary.
To prevent damage to the membrane filter can be installed. A fine mechanical filter can prevent an activated carbon filter chemical damage (eg chlorine).
Also, it may be necessary to rid the system of biological contamination, especially in sea water treatment. Here are eliminated using biocides (usually bromine) discontinuous forming biofilms. Chlorine is used mainly in southern countries for disinfection. Because of the chlorine sensitivity of the membranes must be removed consuming.
Applications:
- The reverse osmosis was developed in the late 1950s on behalf of the U.S. government and NASA, among other things for the manned space flight. It was / is this technology applied to their own urine for long space stays.
- Reducing the concentration of dissolved substances: treatment of water for cleaning rinsing effluent or process water or for the production of drinking water, ultrapure water or aquarium water. To be treated waters may be, for example, process water, wastewater, seawater.
- Increasing the concentration of dissolved substances: concentration of the carrier substance, eg for the production of fruit juice concentrates or compression of must in wine making.
- Manufacture of non-alcoholic beer.
Working principle:
The medium in which the concentration of a particular substance is to be reduced is through a semi-permeable (semipermeable) membrane separated from the medium in which the concentration should be increased. This is exposed to a pressure that must be higher than the pressure created by the osmotic concentration of the request for compensation. This allows the molecules of the solvent against their "natural" osmotic propagation direction in the area, hiking in the already concentrated the solutes are lower.
Drinking bar has an osmotic pressure of less than 2, the applied pressure for the reverse osmosis drinking water is 3 to 30 bar, depending on the membrane and system configuration. For seawater desalination is a print from 60 to 80 bar required because sea water bar with about 30 exhibits a much higher osmotic pressure than water. The Dead Sea is actually an osmotic pressure bar front of 350. In some applications, eg for the concentration of landfill leachate, are still used higher pressures.
The osmotic membrane that allows only the carrier liquid (solvent) and dissolved substances (solutes) holds back, must withstand these high pressures. If the pressure difference, the osmotic gradient more than compensates for the solvent molecules fit like a filter through the membrane, while the "impurity" molecules are retained. Unlike a conventional membrane filter osmosis membranes have non-through pores. Rather, the ions and molecules through the membrane wander through it, by diffusing through the membrane material. The solution-diffusion model describes this process.
The osmotic pressure increases with increasing concentration difference. If the osmotic pressure equal to the applied pressure, the process comes to a halt. It is then in an osmotic balance. A steady flow of the concentrate can prevent this. Concentrate outlet when the pressure is controlled either via a pressure regulator or a pressure exchanger used to build the required pressure in the inlet of the system. Pressure Exchanger energy recovery by reducing the operating costs very effectively a reverse osmosis plant. The energy consumption per cubic meter of water is 4 to 9 kWh.
The crystallization (precipitation) of the solutes must be prevented in the membranes. This can be through the addition of anti-scaling agents (English Antiscaling) or acids can be achieved. Anti-deposition agents are here to polymeric compounds or phosphate Maleinsäurebasis enclosing the forming crystallites and thus prevent crystal precipitation may occur on the membrane. A cleaning of the membrane may still be necessary.
To prevent damage to the membrane filter can be installed. A fine mechanical filter can prevent an activated carbon filter chemical damage (eg chlorine).
Also, it may be necessary to rid the system of biological contamination, especially in sea water treatment. Here are eliminated using biocides (usually bromine) discontinuous forming biofilms. Chlorine is used mainly in southern countries for disinfection. Because of the chlorine sensitivity of the membranes must be removed consuming.
Applications:
- The reverse osmosis was developed in the late 1950s on behalf of the U.S. government and NASA, among other things for the manned space flight. It was / is this technology applied to their own urine for long space stays.
- Reducing the concentration of dissolved substances: treatment of water for cleaning rinsing effluent or process water or for the production of drinking water, ultrapure water or aquarium water. To be treated waters may be, for example, process water, wastewater, seawater.
- Increasing the concentration of dissolved substances: concentration of the carrier substance, eg for the production of fruit juice concentrates or compression of must in wine making.
- Manufacture of non-alcoholic beer.
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