Fresh water is, of course, one of the most crucial resources humans need to survive. Just 2.5 percent of the water on the Earth is fresh, and only 1 percent of freshwater is accessible. This means that only 0.007 percent of the Earth’s water can be used by people without altering it in some way.
Luckily, there are ways to take some of that non-drinkable water and make it usable. The United Nations expects that by 2025, 14 percent of the global population will need to use desalination, a process that removes the salt from saltwater, to get enough water.
So far, countries in the Middle East are the biggest users of desalination. In fact, Israel gets 40 percent of its water supply via desalination. Israel and other nearby countries have almost no groundwater, so desalination came about out of necessity.
Other areas, too, are beginning to look into the technology. California, which recently experienced severe drought, has started to use it to meet its water needs. As more areas need to use new methods to meet the water needs of their growing populations, many will likely turn to desalination. Here are three methods cities can use to solve the fresh water crisis.
Distillation is one of the most common ways saltwater is desalinized. Multi-stage flash distillation involves using heat to cause saltwater to evaporate, which then leaves the salt behind. Basically, the water needs to be boiled on a very large scale.
While effective, this method of desalinization is very energy intensive and expensive. In addition to using a lot of energy to heat the water, it must also be pulled out of the ocean into a treatment plant. This can be complex and expensive, and can also cause damage to marine ecosystems.
These are the main reasons distillation hasn’t been more widely adopted. In some areas, though, people have little choice, and, as more populations grow, the need to rely on distillation increases as well. Making distillation technologies more efficient may help make it more manageable for large-scale use.
Reverse osmosis is a desalination process that has been around since the 1960s and uses principles of both membrane and thermal purification. In this process, water is passed through an osmotic membrane, also known as a semipermeable membrane. This membrane allows water to process through at a rate much higher than the dissolved salt.
Yale has developed a mix of carbon dioxide and ammonia gasses that it uses in a process called forward osmosis. The gases are dissolved in the water and pull water from saline feeds. The salts are then heated, leaving behind drinkable water.
Reverse osmosis still requires a lot of energy, but the need is less than that of distillation. This enables it to be more affordable, which may make it possible to use desalination in more communities around the world, including rural areas.
Solar-powered water purifiers
Using solar stills is a water purification method that has been around for a long time. They use the power of the sun to make saltwater potable.
Simple solar stills are comprised of black containers filled with water and have a clear glass or plastic top to speed up evaporation. Researchers at the State University of New York (SUNY) in Buffalo recently developed a new solar still they say is more efficient and cost-effective.
This new technology, the researchers say, can purify water as much as four times faster than a standard commercial still. It also only costs about $2 per square meter. The use of nanomaterials has allowed modern solar stills to capture more sunlight, and improvements in design have made them more efficient than older versions.
The fact that solar-powered water purifiers are cheap and efficient makes them potentially the best choice for low-income and rural communities. They also give people control over purifying their own water. One potential disadvantage is that they may be hard to implement on a large scale.
Everyone needs fresh water, but as the population grows, it’s getting harder to come by. Some areas have already started using various desalination techniques to meet their water needs. More may find they need to do that in the future. Fortunately, there are options for both cities and rural areas alike.
This article was written by Megan Ray Nichols. If you enjoyed this article, please visit her page Schooled by Science.