Desalination can turn seawater into potable water.
What is Desalination?
Few would disagree that the planet is running out of sources
of vitally important freshwater. And - as the worldwide
population continues to rapidly increase, and as droughts
continue to plague the planet - most would agree that
something needs to be done quickly to alleviate this growing
concern. Otherwise, by 2025, two-thirds of the world’s
population could live in countries with severe water
shortages.
97% - What About Sea Water Treatment?
With 97% of the planets water found in the oceans, one possible solution is desalination. This term refers to any of several processes that remove salt and other fine particulates from ocean water, treated wastewater and brackish water (a mixture of fresh- and saltwater). More than 100 countries desalinize water; Saudi Arabia leads the way, accounting for 24% of the worlds capacity.
Reverse Osmosis - To Treat Sea Water!
Of the many desalination methods that exist, reverse osmosis is the most common, constituting 49.2% of installed desalination capacity worldwide, as of July 2006.
Reverse osmosis is accomplished by pumping seawater at high pressure through a permeable material that allows the water to pass through, but not the salt and other minerals. This is often done in multiple stages. The end result of the entire procedure is usable freshwater. Close to 50% of the supplied water is recovered, with the other half rendered unusable due to the high mineral content. Israel is home to the planets largest reverse osmosis plant, capable of producing 100 million cubic meters of water per year.
Distillation
Another popular method of desalination is known as
distillation. This process uses evaporation to separate salt and other impurities from saltwater. As the water is heated,
it evaporates and leaves behind the unwanted materials.
The steam is collected and condensed in a container, while
the waste product is ejected. An advantage of distillation is
that it uses thermal energy (sunlight) rather than
conventional fossil fuels as its source of power, resulting in a
more environmentally friendly solution. The drawback is that
it yields less freshwater than does reverse osmosis.
No matter the method of desalination used, an extremely
concentrated - and potentially harmful - waste product is
always produced. (The U.S. Environmental Protection
Agency has classified it as industrial waste, thus requiring
proper disposal.)
50% of the supply water is recovered
In the case of reverse osmosis, since 50% of the supply
water is recovered, it means that the other 50% is now
twice as saline as it was originally. If a desalination facility is
located along a coastline, it is possible under certain
circumstances to return this waste water to the ocean, but
only if it does not exceed a safe level of salinity. If the
facility is located inland, the challenges of proper waste
product disposal increase, as one cannot simply release it
into freshwater streams, ponds, lakes, etc.
Similar to many solutions discovered by mankind,
desalination produces a useless by-product in the process of
creating a useful product. Will it come to be recognized as a
viable solution? Time will tell.
Treatment Technology Options
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