Reverse Osmosis 4 marks important question

Reverse Osmosis



Write short note on “Reverse Osmosis”.

Reverse Osmosis


    • Reverse Osmosis is a process in which dissolved inorganic solids (such as salts) are removed from a solution (such as water).
    • This is accomplished by water pressure pushing the water through a semipermeable membrane.
    • The RO process works depending on the salt content levels in the water.
    • The pressure is applied accordingly and with the help of membrane that is semi-permeable and a 0.0001 micron, the water is forced to cross it.
    • All the contaminates that are present in the water get caught into the membrane.
    • When this is happening the pure water goes in a separate ways and the impure one goes into another way.



  • Due to the cross filtration, the water that is impure and contains the contaminants is swept away.
  • This method of water production does not use waste heat source, unlike fresh water generator, to desalinate the sea water to convert it into fresh water with low salt ppm.
  • The osmotic pressure of sea water is 28 bars but to overcome system losses and the fact that the sea water concentration increases as it passes through the length of the membrane, much higher pressure around 40-70 bar, depending upon the plant size, is required.
  • A triplex plunger pump is popularly used to produce high pressure across the membrane.
  • The membrane used has a very fine barrier of dense holes which only allows water and gases to pass through, while preventing the passage of solutes such as salt and other impurities.
  • The fresh water produced after this stage is treated with chemicals and ultraviolet treatment to make it drinkable and useful for other purpose.




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