There are many different types of water purifiers available in market. Water purifiers range from simple water filters to advanced purifiers using membrane technology for water filtration followed by disinfection with UV lamp filters.
Here are the common water purification methods used for filtering domestic water:
Membrane technology purification
Reverse osmosis is the most widely used water purification method. RO uses membrane technology to remove dissolved salts, impurities and germs from water. The semipermeable membrane separates germs and dissolved chemicals from water. The membrane has very fine pores that allows only water to pass through it leaving behind all the harmful chemical, dissolved salts and microbes suspended in water (size of RO membrane pore is approximately .0005 micron which is slightly larger than the size of water molecule).
The drawback of RO is that it alters the taste of water and may remove some essential mineral from water. There are certain brands of RO which claim to retain the essential minerals in water. The semipermeable membrane require regular care and maintenance. To know more about RO process refer to “How does RO water purifiers work” RO technology is advisable in the areas where the quality of water is hard and high in TDS.
UF (Ultra filtration) purification method uses membrane similar to RO membranes but with bigger pores. UF membranes essentially removes all colloidal particles including most pathogenic organisms and turbidity but fails to remove the dissolved solids and salts. Unlike UV purifier, UF water purifier physically removes all the germs and bacteria from the water. Ultra-filtration water purifiers are as good as RO water purifiers when the water supplied to homes is not very hard and has less TDS. RO is only required when the water has too much TDS and hardness.
UV purification or e-boiling
UV water purification is a method of water filtration which uses ultra-violet light to kill all germs, bacteria, microbes, cysts, etc. in water. Ultraviolet water purification is a simple but effective process that destroys around 99.99% of the harmful organisms in water. There is a tiny mercury lamp inside the purifier that produces short wave UV radiations. These radiations irradiate the water and penetrate the cells of bacteria and viruses, destroying their ability to reproduce. The microbes and organisms fail to multiply and eventually die. This purification method only kills the germs but the bodies of the dead germs remain in the water. Separate filters are required to remove the germs physically. UV water purification is usually done in conjunction with other forms of filtration such as reverse osmosis or activated carbon filters.
Candle filter purifier
Water purifiers with candle type filter have a very basic operating mechanism. The candle has very minute pores. Any particle which has the size larger than the pores gets blocked out and cannot pass on to the clean side. It does not require any electricity for operation. But the downside is that it fails to block microbes and so water still needs to be boiled before consumption. Also the candle needs to be cleaned up frequently for effective operations.
Activated carbon filter purifier
This water purifier use activated carbon filters for purification process. The carbon filters can remove chemicals like chlorine, pesticides and impurities to a great extent. The filtration changes the taste and odor of water. It does not require electricity for operation. But it is also not very effective in removing microbes from water.
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