Sunday, March 29, 2009

Types of Water Filtration

Water filtration is the process of purifying water in order to remove unwanted solids, microorganisms, gases and chemical substances. The water is passed through a medium which retains the solids and allows only water to pass through. It is important that one gets clean, purified water to avoid waterborne diseases. There are various types of water filtration. They include; ion exchange, distillation, filtration, ultra-filtration and reverse osmosis.


In this method of water filtration, the water is heated to boiling point where it vaporizes. The vapor is then condensed and stored after it has been collected. It is beneficial since it takes away a wide range of pollutants. The main disadvantage of this type of filtration is that there could be other harmful chemicals that vaporize together with the water and these could be ingested assuming that the water is purified. These are substances that could be having the same boiling point as water. Distillation also uses too much energy.

Ion Exchange

This process involves the exchange of ions. Water is passed through bead-like spherical resin materials. The water ions are exchanged with the ions attached to the beads. This method is usually used for deionization and softening of water. However, this method of filtration works best when used together with other types of filtration such as carbon filtration. This is because it does not take away many of the microorganisms found in water.

Carbon Absorption

In this method, water passed through carbon filters gets rid of unpleasant tastes, smells, chlorine, gases, and many chemicals. Occasionally, this method gets rid of microorganisms. This type of water filtration will not have an effect on hardness of water, heavy metals and solids absorbed in water. The water collected after this method of filtration can be bettered by filtration using another method.


In this method of filtration, water is passed through an ultrafilter which acts like a molecular sieve. It takes away dissolved molecules according to their size. It is beneficial in that it efficiently takes away many particles, microorganisms, pyroids and colloids exceeding their rated size. It also gives very high quality water and uses less energy.

Reverse Osmosis

Reverse osmosis as the name suggests, is the opposite of natural osmosis. Here hydraulic pressure is put on the concentrated solution to act against the osmotic pressure. Purified water is then collected on the lower part of the membrane. This type of filtration produces water that is purified. The water collected does not contain any salts, sugars, ions and molecules that had been dissolved before filtration. Water filtered using this method, will not have the pleasant tastes that carbon filtered water has. This method is advantageous as it needs minimal maintenance.

Ultraviolet Radiation

This method of water filtration is mainly used to kill germs. Mercury lamps producing 254nm UV light are used. The microorganisms in the water are inactivated when the DNA and proteins of their cells absorb Ultra Violet radiation.

It is advisable that one should combine two or more filtration methods to get better quality water.

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