Deaeration/Degassing
Dearation is the process of reducing the level of dissolved air gases in water to levels below the natural level for a specific purpose.

Degassing is the process of reducing a high level of certain gases down to the natural level.

The following are specific types of Deaeration & Degassing:-

Thermal
The water is dispersed to give a large surface area and is heated to temperatures of 105oC to enable a small vent stream to carry away the dissolved gases. Three types of configuration are possible: spray type, packed tower, and tray type tower. Each type has a storage drum.

Vacuum
The water is dispersed in a packed tower under vacuum conditions. This is generally used where the water is required at a lower temperature than for thermal units. Alternately, a packed column can be used where in a counter current flow of an inert gas such as nitrogen or carbon dioxide the oxygen is removed.

Membrane
This is similar to B) but the treated water is separated from the vacuum of inert gas flow by a semi-permeable membrane. These units can be supplied in a very compact form.

Degassing
This consists of a packed tower and sump with a counter current flow of air up the tower as the dispersed water flows down the tower. This allows the removal of high levels of a soluble gas down to a level approximately equal to that of the gas in the atmosphere. The main use is removing carbon dioxide generated in ion exchange processes to lower the anionic load on the anion column to lessen the amount of regenerant chemical used.

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