What is Water Desalination and Should It Come With a Health Warning?
With so many countries currently investing millions into desalination plants, is it totally beneficial or does drinking water from the sea have its downsides as well?
What is Desalination?
Desalination (also spelled desalinization) is the process of creating fresh water by removing saline (salt) from bodies of salt water. There are varying degrees of salinity in water, which affects the difficulty and expense of treatment, and the level of saline is typically measured in parts per million (ppm). The US Geological Survey provides an outline of what constitutes saline water: 1,000 ppm - 3,000 ppm is low salinity, 3,000 - 10,000 ppm is moderate salinity, and 10,000 ppm - 35,000 ppm is high salinity.
Water that contains saline levels less than 1,000 ppm is generally considered fresh water, and is safe to drink and use for household and agricultural purposes.
Desalination Processes:
There are numerous methods of desalination. Reverse osmosis is currently the most commonly found type of desalination and multistage flash distillation is the method that currently produces the most amount of desalinated water.
Reverse Osmosis:
Reverse osmosis is a process where pressure is used to push the water solution through a membrane, with the membrane preventing the large solutes (the salt) to pass through. Reverse osmosis is generally considered to be the least energy consuming of all the large-scale processes.
There are several setbacks of reverse osmosis. The membranes are currently prone to gather too much bacteria and 'clog-up', although they have improved since they were first used. The membranes deteriorate when chlorine is used to treat the bacteria.
water qualities that reverse osmosis produces, along with the considerable pre-treatment that the salt water requires. Dumping the wasted salt solution back into the ocean makes the process more difficult and has the potential to harm ocean life.
While reverse osmosis is effective for removing a variety of contaminants in water, it does NOT remove volatile organic chemical (VOC's), chlorine and chloramines, pharmaceuticals and a host of other sythetic chemicals found in municipal water.
In general, if the contaminants are larger in size than water molecules, those contaminants will be filtered out. If the contaminants are a smaller size, they will remain in the drinking water.
Thermal Desalination:
Thermal desalination is a method of cleaning water that can occur through many different processes and includes removing salt as well as other contaminants. All thermal desalination is the process of heating the water solution and gathering water when the vapour cools and condensation occurs.
The energy required for start-up and power desalination plants is a huge expense and because most current power sources are derived from burning fossil fuels, it is generally looked upon as just a matter of choosing one environmental crisis over another. If regions situated away from the coast or in a high altitude try to use desalinated water, it is even more expensive process.
Arctic Blue Waters:
Arctic Blue water is supplied from a natural water source water, which has not been contaminated by humans. Arctic Blue water has not been de-mineralized, therefore considered to have health advantages over de-mineralized water. The naturally occurring minerals leave the water with a satisfying taste.
Other setbacks are arguable
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Posted on 25th February 2013 .