Making Seawater Potable with RO

The dilemma of making seawater drinkable has been expressed by Samuel Taylor Coleridge in The Rime of the Ancient Mariner, which goes: “Water, water, everywhere, nor any drop to drink”. One has to admit that it’s quite ironic to live in a planet that’s teeming with water that isn’t all drinkable.

Or is it? As technology progressed, so did the possibility of making seawater drinkable: enter the scientific process of desalination, which removes dissolved minerals from seawater (including the salt). Different processes have been developed to perform desalination, and one profound candidate for it is known as reverse osmosis or RO.

Reverse osmosis is more commonly used by desalinization plants all over the world. The system relies on high-tech membranes through which water can pass through, but dissolved salts couldn’t. RO works like this: a saline (salty) solution sits on one side of the permeable membrane, and a less-salty solution sits on the other. In this setup, water from the less-saline solution automatically moves to the more saline side, causing the salinity of the two solutions to equalize.

Why would we want to desalinize seawater in the first place? For one, seawater provides an unlimited water supply that’s practically drought-proof. The sheer amount of seawater is grounds alone: 97 percent of the Earth’s water is seawater, while only 1 percent is fresh and 2 percent is frozen. There are currently 7,500 desalination plants worldwide delivering potable water to people, and it’s just the beginning.


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