Desalination is the process used to remove salt from sea water, making it suitable for human consumption, animal consumption and for use in agriculture. Various nations around the world, and in particular the United Arab Emirates, are currently using the desalination process on a huge scale to supply drinkable water to millions of people on a daily basis, and as a result governments in the developing world are taking notice.
How does the desalination process work?
There are various ways in which salt can be removed from sea water however in large scale plants it is done with a method called reverse osmosis. This process involves forcing sea water, under tremendous pressure, through a specialised polyamide membrane. This membrane stops salt from passing through so that the water produced at the other end is clean and drinkable.
Unfortunately, sea water contains numerous species’ of microorganism which degrade the expensive membrane if they make contact. For obvious reasons these microorganism need to be removed from the water before the ‘filtration’ stage and are done so by adding chlorine to the water. Chlorine also has a tendency to break down the fragile membrane though and so this also needs to be removed prior to filtration.
As you can probably guess the desalination process isn’t cheap, mainly because of the huge amount of energy needed to force the sea water through the membrane in the filtration stage. Thankfully scientists around the world are looking at developing new technologies though, many of which aim to reduce the amount of energy needed to actually separate salt from sea water.
One such technology is being developed at the University of Texas. Here they are experimenting with passing an electrical current through sea water as it passes through a tiny chip. The electrical current has the same effect as the polyamide membrane in the current desalination process and separates the salt from the water. Unfortunately this technology is still in the very early stages of development and at present only removes around one quarter of the salt but it certainly has potential for the future.
Desalination and the developing world
It’s no secret that there is a huge shortage of drinkable water in numerous parts of the developing world. Millions of people go without clean water on a daily basis and as populations continue to increase this will only get worse.
The oceans of the world are inexhaustible though and with the help of the desalination process drinkable water is potentially there for the taking. It would entail huge costs building desalination plants and laying pipelines around entire countries though; and this is the only factor stopping many areas of the developing world from taking advantage of the process.
Saying that, the same technology used in large scale plants is currently being used on a smaller scale to equip villages and towns with solar powered desalination units. Obviously the units have to be within travelling distance of an ocean or salt water area but it’s certainly a step in the right direction…and one that can be used as a basis for developments in the future.