Production of pure water
It is easy to obtain 20-100 ml or 0.68 – 3.38 FL OZ of distilled water at home without water distiller. By using the water distiller at home or in the laboratory during the day you can produce tens of liters of pure water. But what to do when hundreds of liters are needed every day?
In the industrial production of pure water the following different methods of water purification are competing against each other: Deionization, Reverse Osmosis (RO water) and Distillation. Following is a brief overview of these methods.
Reverse Osmosis water purification
For the Reverse Osmosis water purification the semi-permeable membrane is used. The membrane allows passing through the clean water, but retains the dissolved salts. The speed of water treatment is limited to the rate of diffusion. Water with low solute concentration naturally flows through the membrane to the area of high solute concentration. This is known as an osmotic pressure. By applying the pressure to reverse the natural flow of solvent, we can get Reverse Osmosis (RO). The Reverse Osmosis (RO) technology of water purification nowadays is commonly used for drinking water purification and sea water desalination.
Deionization of water
A typical installation of water deionizer consists of two columns, filled with grains of ion-exchange resins. In the first column the hydrogen ions are trapped or more precisely exchanged against the cations of salts presented in the solution. In the second column the same thing is happening with the anions, only they are exchanged against the hydroxyl group. This water is called deionized water because it’s free of any ions.
Recently, solar distillers for water desalination have become more and more popular. They work in the deserts and dry areas where the sun is much more than the fresh water. Solar desalination plant consists of a large tray-pool with salt water, pockets for collecting of the distillate, and a transparent roof made of glass or plastic film. Salt water flows slowly through a channel, and the hot desert sun slowly evaporates it. The roof on top of it is the coolest because it is irrigated by the cold saline water. The condensed water flows down on the inner surface of the roof where it is collected in pockets.
Putting the salt back into the distillate water
Well, you can try to wash in distillate water, no problem; it’s a soft water. You can even drink it. A very strong and flavor rich coffee and tea are available only with distillate water. In the desalinated water, the extraction is better, and colloids, including coffee, in the distilled water are more stable. However, drinking just the distilled water is not recommended, because the water should contain some trace elements in order not to harm the body in a long term run. Therefore, if you want to use the distilled water or reverse osmosis (RO) water for drinking it’s recommended to put the salts back. For your RO water purification equipment at home you can install an extra mineral cartridge for water mineralization. The quality and taste of this water is almost the same as that of natural spring water.