Desalination of Water Using Distillation

Desalination is a process that involves the extraction of salt from sea-water. It is a great resource to get fresh and clean water. Unfortunately, desalination plants are expensive to build, costs high energy, suitable for seaside cities, and limited value for the cities that needed it most. As world necessity for water is getting increased day by day. There is more death caused by unhygienic water than the death caused by war. Therefore, it has now become one of the engineering grand challenges to provide access to the clean water. Distillation is an oldest method that has been used for the desalination of water. It is a phase-separation method and involves two steps – water vapors are produced by heating the sea water, and then the vapors are condensed to produce fresh water. There are various distillation process (techniques) are being used to produce the fresh water like Multistage Flash(MSF), multi-effect distillation(MED), vapor-compression (VC), and waste-heat evaporator technique. These all work on the same principle of reducing the vapor pressure of water within the unit to allow boiling at low temperature and thus reducing the need of additional energy/heat. They are designed in a way so that they can conserve the heat energy produced within unit by exchanging the heat of compression and heat of vaporization. MSF technique is very effective among all. It produces high quality of water and there are fewer chances of getting bacterial or contaminated water as the water is boiled in the process. To make the process more cost and energy efficient, improvements are being made to the existing process. Moreover, there is also the new process technique that has been introduced. It includes membrane distillation and solar distillation. Additionally, to lessen the cost, the renewable energy resources can be used to power the desalination plant.