Water

Desalination of Sea Water

Desalination is a process that separates salt from sea water. It is also known as desalinization or desalinisation. This process does not only remove salt from sea water but also removes other minerals.  This process produces two types of end products that result from this process, one is salt and the other one is fresh water.

How does it work?

There are three types of distillation process that are being used now.

  • Vacuum distillation
  • Multi-stage flash distillation
  • Reverse osmosis

Vacuum distillation:

This is the traditional method to make fresh water from sea water. How does it work? During this process the pressure above the sea water is reduced to a pressure lower than its vapor pressure,

Vacuum distillation:

This is conducted at a reduced pressure. The boiling point of liquid becomes lower at a reduced pressure. In other words, the compound would not have to be heated to its normal boiling point for it to boil. This technique is particularly used for compounds that have higher boiling point. Thus, it might decompose if boiled at the regular atmospheric pressure. A mechanical pump or water aspirator could be used to provide vacuum.

Multi-stage flash distillation

This process takes place in vacuum at relatively low temperatures. The vapor that is produced is then condensed to get fresh water. Since the process takes place in vacuum, the boiling point of water is low. Therefore, it requires less energy to reach its boiling point.

Before sending the cold sea water into the brine heaters, it is passed through condensing coils where preheating takes place. Then the steam is flashed into to the chambers to form fresh water.

Reverse Osmosis:

This is a process where pressure is applied to the water at one side of the membrane through which large molecules and ions are filtered.

Above are the main three types of processes that are popularly being used today to remove salt from sea water.

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