03-01 Desalination - John Bulloch

If there is a guaranteed growth industry, it is water desalination. All of the water stressed nations are engaged in some kind of desalination research and development. The big issue is the use of filtration systems to remove salt rather than distillation because of the reduced needs for power. Look to solar powered desalination systems in the future.

We have about 38% of the land mass of the world that is either arid or semi-arid facing a future of desertification. The big issue now and in the future is water for agriculture and drinking. The problem is that 97% of the world’s water is salty.
There are two basic technologies for removing salt. It is either distillation or filtration. The technology is not complex in theory, and yet most of the water stressed nations are engaged in new technologies, mostly linked to filtration because of the lower power costs.
The schematic shows the concept behind distillation. Boil salt water and the water vapor is free of salt.
I remember my days as an engineering student examining various industrial processes and learning how industry often engages in some form of water purification through distillation to remove salts and other impurities in the water.
The photo shows distillation being used to produce pure distilled water for making whisky.
An early desalination process based on sending salt water through membranes that removed the salt was developed by Israel. Most of 18,000 desalination plants in service today use some form of membrane filtration.
The photo shows a large desalination plant in Israel based on filtration. Israel uses desalinated water not just for agriculture and drinking, but for refurbishing water levels in the Sea of Galilee.
Again when you get to a range of applications for desalination, like cruise ships or industry, you have thousands of small-scale filtration facilities. Often it is much more than removing salt, but a range of other chemical impurities.
I did one of those cruise ship tours and was told to my surprise that the ships not only desalinate sea water, but add minerals to the water that our body needs. And to my surprise those big ships can store 500,000 gallons of fresh water.
If I could look to the future I would see large applications of solar power and sea water filtration combined. How about Morocco? How about the USA? Exciting.