Seawater Desalination Projects

The Earth has a limited supply of fresh water sources, which becomes problematic as the planet's population increases. Still, humans have discovered inventive ways to make use of the Earth's other bodies of water. Water desalination, or the process of changing saline seawater into freshwater usable by humans, has a lengthy history, though there are both pros and cons to this kind of water treatment.

History

• Despite many recent advances in how humans desalinate water, it is not a new idea. In fact, water desalination is one of the earliest kinds of water treatment, with roots reaching back to ancient civilizations. In the 1600s, Sir Francis Bacon experimented with removing salt from seawater by filtering it through sand. His method did not really work, but it laid the groundwork for modern water desalination projects. Since that time, water desalination has evolved drastically.

Distillation

• One method for water desalination projects is that of distillation. This process involves heating water to the point where it becomes steam. As the water evaporates, it leaves behind salt and other contaminants. The steam is then cooled in another location; the steam becomes water once more, and cool, clean, freshwater is left behind. This type of method needs large amounts of heat, and is typically impractical for large-scale desalination projects.

Reverse Osmosis

• Reverse osmosis is the technique most often used in professional seawater desalination projects in 2011; it removes salt from seawater. During this method seawater is placed under very high pressure against a filter called a semi-permeable membrane. The holes on this filter are so small that water molecules can just squeeze through, while salt and other dissolved contaminants are too large and are left behind.

Benefits

• One of the most obvious benefits of wide-scale water desalination projects is the fact that more drinking water is available to people that need it. This is particularly beneficial in parts of the world where fresh water sources are scarce, including parts of California and the Middle East. Water desalination also has a few environmental benefits, as less fresh water needs to be transported to these areas, saving on container costs and energy wasted during transportation.

Drawbacks

• Like most kinds of environmental projects, water desalination is not without its drawbacks. First, water desalination plants tend to pollute the surrounding environment. Not only are the plants using some kind of energy to run, which often results in greenhouse gases or other emissions, but the process of desalination can pollute water. After the process, excess seawater is usually returned to the ocean, though it now has a much higher concentration of salt and other contaminants than normal. This can mess up the local ocean ecosystem by changing the salt in seawater to unnatural levels.

  Additionally, water intakes at the plants can cause damage to nearby plants and aquatic life. Finally, water desalination plants are quite costly and may not always be worth it in terms of profits and economic gains.