Purifying water has become a trend in reducing water borne diseases and to limit the water pollution that we now have. Among various water purification techniques, reverse osmosis has become one of the most popular and safest ways to maintain clean drinking water.

Reverse osmosis is the process wherein water move from an area of high solute concentration to an area of low solute concentration. It is known as reverse osmosis because simple osmosis involves the movement of water from an area of low solute concentration to an area of high solute concentration through a semi permeable membrane.

Osmosis can be illustrated through imagining a semi permeable membrane with salt water on the other side and tap water on the other side. Through osmosis, water moves from the side of the tap water to the side of salt water through the semi permeable membrane. This is because the water becomes attracted with the high salt concentration on the other side. In reverse osmosis, the water on the salty side will move to the tap water side leaving impurities behind. In water purification process, the water leaves an area with higher concentration of impurities to an area of lesser impurities rendering the water to be clean and safe to drink.

In reverse osmosis, the semi-permeable membrane only allows the movement of water from one side to another and does not allow the movement of bacteria, urea, glucose, sodium, chloride and calcium leaving the impurities on one side and allowing clean water to go to another side.

How Does Reverse Osmosis Happen?

Since reverse osmosis is the exact opposite of the normal osmosis process, a pressure is applied to overcome the osmotic pressure in a normal osmosis process. When the pressure is applied, the solute is retained on the pressurized side of the membrane and the water is allowed to pass through the other side. The membrane is semi-permeable, which means it is selective. It does not allow larger molecules to pass trough making the water more purified. The membrane used in reverse osmosis has a dense polymerized layer allowing the separation of the solvent from the solute.

Drinking Water Purification

Various countries use reverse osmosis mechanism to purify water for cooking and drinking purposes. Purification machines usually involve the water to pass through various steps and various compartments including:

  • Sediment filter- The first compartment allows trapping of large particles such as calcium carbonate and rust.
  • Second sediment filter- Some equipment have a second filter with smaller pores to trap smaller insoluble particles.
  • Carbon filter- The third layer is the activated charcoal filter used to attract organic materials such as chlorine. These materials need to be trapped as they can destroy the semi permeable membrane.
  • Reverse Osmosis Membrane- The main layer is a thin film of composite membrane for the reverse osmosis to occur. After which, some may have a second carbon filter to remover remaining organic compounds not removed in this membrane.
  • Ultraviolet light- Some machines also have UV lamp to help destroy microscopic organisms that may have passed through.

After the rigid process, water that is purified through reverse osmosis is very safe for drinking and used for cooking purposes. If you are interested in this water filtration system, there are household filtration systems that you can get.