Reverse Osmosis~ Concept of Reverse Osmosis

What exactly is Osmosis, Osmotic and Reverse Osmosis

Osmosis process was first discovered in 1748 by a French Scientist whom observed water diffuse spontaneously through a pig bladder. In nature, contaminant which dissolved into water normally exists in the form of ions, such materials is commonly refer to as salt in Chemistry. In pig bladder which is lined with membrane that has fine enough pore sizes that will not permit the transfer of salt ions, but large enough to still allow the water ions and molecules to pass through, is used as a separation medium between water having two different concentration of salt, water will generally transfer from the least concentration side to the higher contamination side as equal concentration will gives equal energy potential state. The flow will stop when either the two side has equal concentration of contaminant or when the water level difference cause a pressure difference large enough to stop the process. This apparent water pressure is known as osmotic pressure and this process is known as osmosis. (fig.1)

Reverse Osmosis, as its name implies, when apply a pressure that is higher than the osmotic threshold pressure on the higher concentrated contaminant side, the water molecules will migrate back into the lower concentration side, thus generation of cleaner water.(fig.2)

Reverse Osmosis membrane typically employs membrane with less than 5 angstrom (1 angstrom = 1/10,000,000th Meter compare with human hair which is 750,000 angstrom diameter on average), the synthetic semi-permeable membrane this days often used materials which has charge particles on its surface and will even reject more than 85% of the metallic and other polar molecules smaller than its opening. Compare with size of virus which has size in the range of 90 to 1000 angstrom, size of bacteria, which has size in the range of 2000 to 2,000,000 Angstrom, the reverse osmosis membrane technology when installed properly and used with check valve can effectively sterilized the water.

Reverse osmosis process has the following added advantage:

1.      Disinfection of water

2.      The process is entirely environmental friendly as it does not produce any chemicals or contaminants to the environments.

3.      The process is reliable and proven over time. It is very stable and the water quality is consistent over time.

4.      The unit uses very little power, only requirement is adequate static water pressure. For most residential situation, the system may be install in-line without any added equipments.

5.      Small size and has a lot of flexibility in where to install the unit.

Fig.1(Click to enlarge)

Fig.2(Click to enlarge)