The Process of Desalination

November 25th, 2013

Japan’s Fukuoka Water Plant desalinates seawater for 150,000 citizens.

Desalination plant

Image via Arun Katiyar (Flickr)

The Process of Desalination

If there is one cruel fact none of us can deny, it is that water is becoming a scarce commodity for many people on the planet. Some people blame global warming, others blame climate change; I tend to think one directly affects the other, so it’s both in my opinion. But, whatever the cause, we need to keep America, and the rest of the world, afloat with plenty of safe water. Water desalination is not something new. It is, however, an uncommon form of water treatment. As our water supplies continue to dissipate, we need to consider the desalination process, and how it will help us and the rest of the world ensure that we have enough safe drinking water.

What Is It?

Let’s begin by discussing what water desalination actually is. The process of desalinating water means that we are removing primarily salt, but also other minerals, from saline water. The desalination process is commonly used on sea vessels, particularly those with long-term water-bound missions such as submarines. Desalination allows those on board the vessel access to plenty of “fresh” water without the necessity of storing gallons of H2O, which would account for too much weight and take up too much space.

How We Desalinate

One of the oldest forms of purifying water is distillation, and that is how we desalinate saltwater. On ships, and in emergencies, the sun can be used to desalinate water. Desalination plants also use heat in water desalination. The desalination process uses the basic water cycle you learned about in science class to our advantage. The sun, or other heat source, evaporates the saltwater. As the salt water rises and reaches cooler temperatures, it turns into rain or dew and “falls” back down into a catching container salt free.

Other Uses for Desalinated Water

Aside from converting salt water into consumable water, another primary use for water desalination is irrigation. Deserts and other regions in the world riddled by drought are faced with the nearly impossible task of growing food. You cannot plant a field of anything if you cannot water it. Desalinating seawater gives food growers the ability to irrigate their crops and provide necessary sustenance to the water barren region. This is an important consideration if other viable options are not available for the region in need of fresh water.

The Cost of Desalination

Desalinating water does come with some costs, however, not only in terms of actual expense, but also in terms of environmental concerns. The actual cost comparison between using desalination as a form of water treatment over other methods varies so drastically, and depends so much upon the individual plant’s process, that it’s almost impossible to quantify which method is more economical. In some cases, desalinating water can beat the cost of treated bottled water; in other cases, it cannot. It truly depends on numerous variables.

Perhaps another gauge in determining whether desalinating water is good for a specific area is the environmental cost. During the desalination process, brine composed of salt, other minerals, and the chemicals used to treat the desalinating plant is left behind. This brine must be disposed of, and is often returned into the ocean via the wastewater route from other water treatment plants. Another concern is the intake of the salt water in the first place. We simply cannot just take in as much seawater as we feel like. This destroys critical ocean ecosystems and the sea life they support.

This being said, there are certain areas in the world that simply must desalinate, and if done properly, the process can return fresh water with minimal environmental impact. Not to mention the benefits of evaporation desalination if you are stranded without fresh water yet have access to salt water. It will save your life.

Who Desalinates

Whom throughout the world that desalinates can serve as proof that this water treatment method is an effective way to get fresh water to the masses? The primary desalinating region on our planet is the Middle East, which makes perfect sense if you think about it. The countries that make up this region all have one thing in common: they all have dry, arid climates with little to no rainfall. They also have plenty of access to ocean water. It is no wonder that these countries use a water desalinating process to gain access to the fresh water they so desperately need.

On our soil, Arizona, California, Florida, and Texas all have operating desalination plants or are constructing desalination plants for future use. Again, in these areas, the necessity for desalinated water is becoming prevalent to support agricultural growth and human consumption.

Desalinating water is also a viable solution to many third world countries in desperate need of clean water. The solar treatment process is also quite effective in killing bacteria, protozoa, and viruses in water supplies. This is why although some view desalination as a costly water treatment process to both the economy and the environment, we must consider it as a viable option to those in need of usable water where the water and the solar energy can work together to desalinate salt water. Emerging technology is also finding ways to desalinate water with far less cost, which is great news for all of us!

 

Written By: Lynn Taylor


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