REVERSE OSMOSIS DESALINATION

Osmosis:

When fluid of different concentration in a vessel are separated by a membrane, the dilute solution will flow through the membrane into the concentrated solution.

Osmotic pressure:

The level of dilute solution drops and the level of concentrated solution rises until an equilibrium is reached. The pressure difference between the two levels is called osmotic pressure.

Reverse osmosis:

If a pressure excess to a osmotic pressure is applied to the concentrated solution, the flow is reversed from the concentrated solution to  the diluted solution.

Membranes used:

• Hollow fine fibre
• Spirally wound

For sea water application membranes used:

• Polyamide
• Polysulphonate

In reverse osmosis desalination:

Pic: Reverse osmosis desalination

• Sea water feed is pressurized using high pressure pump.
• The high pressure sea water is passed through a chamber containing a permeable membrane.
• The membrane stops the passage for salt and allows pure water to pass.
• The clean water is then sent to a potable water tank.