REVERSE OSMOSIS

Principle: 

Osmosis is a natural process that when a pure water and saline water are separated by a membrane which can permit only water molecules to pass through. Pure water will flow into the saline water due to a tendency called osmosis. This natural tendency can be reversed by applying an opposite pressure to the saline water so that water molecules from saline water tend flow out as pure water. This is called reverse osmosis.

Process:

·         It consists of several horizontal compartments separated by semi-permeable membranes.

·          A pressure of 15-40 kg/cm² is applied to the saline water to force its pure water to pass through the semi-permeable membrane leaving behind the dissolved salts.

·         The pure water from different compartments are collected and the concentrated saline water left out is discarded.

·         The membrane is generally a thin film of cellulose acetate or polymethyl methacrylate.

Advantages:

1. This method is economical, compact and very simple.

2. Life time of the membrane is high about 2 years.

3. Easy to replace the membrane within two minutes.

4. Ionic, non ionic, colloidal and high molecular weight organic matters are easily removed.