Israel is another instance of desalination in action. Among the many nations in the Middle East attempting to ward off water shortages, Israel is counting on desalination plants.
The third of five major plants planned off the coast of Israel went into operation in January , and, for now, it's the largest reverse osmosis desalination plant on Earth. Once all the facilities are complete, they're expected to provide about two thirds of the country's drinking water [source: Associated Press ].
Desalination techniques are also being developed on a much smaller scale. Portable desalination kits are a prime example. Researchers at MIT are working to bring desalination down to the nano level, harnessing electrostatic ion-selective membranes to avoid requirements and disadvantages often associated with the reverse osmosis method, like the need for high levels of pressure and the occurrence of inadvertent clogs and foulings. They call the process ion concentration polarization , and they envision it helping in disaster zones.
The units wouldn't produce the vast amounts of freshwater rendered by plants, but they would be self-contained, portable and powered by solar cells or batteries.
Many units could be distributed during relief efforts and provide drinkable water until infrastructure functionality was reestablished [source: MIT News ]. It seems the future of desalination is wide open with different research institutions continually looking for ways to make the process more efficient and more cost effective.
Sooner or later, we might enjoy the occasional long, cool sip of water that, left untreated, would have been a deadly cocktail. Sign up for our Newsletter! But as populations grow elsewhere around the world, and climate change drives droughts, desal has become an increasingly attractive option. Analysts forecast an annual growth rate for the industry of close to 9 percent for at least the next four years.
You can see just how much desal has boomed recently in the graph below. The boom in desal brings with it a tidal wave of brine. Because this stuff is denser than typical seawater, it sinks to the seafloor and disrupts vibrant communities of life, which find themselves wanting far less salt and far more oxygen.
Facilities can mitigate the environmental impact by, for example, mixing the brine with seawater before pumping it out, to dilute it. They might also take care to expel the byproduct where currents are strongest, thus dissipating the brine quicker. Inland, a plant might evaporate the water in pools and cart away the remaining salt.
But brine is more than just hypersaline water—it can be loaded with heavy metals and chemicals that keep the feedwater from gunking up the complicated and expensive facility. Dilution may help with the hypersalinity problem, but it doesn't get rid of the chemical toxins. The most common type of membrane separation is called reverse osmosis. It involves pushing the water through a series of microscopic sieves rolled up into larger cylindrical filters.
The energy-intensive process separates pure water from both salt molecules and impurities. All desalination methods produce a concentrated waste product composed of the salts found in seawater and chemicals used in the process.
Disposal methods for the concentrate include dumping it back in the ocean, injecting it into deep underground wells, storing it in above-ground evaporation ponds, and zero-liquid discharge procedures that produce a solid waste product. Seawater desalination is one of the most expensive sources of fresh water.
The total costs of desalination, including the costs of planning, permitting, and concentrate management, are high, both in absolute terms and in comparison with the costs of other alternatives.
Because desalination requires a lot of energy the plants are also very expensive to maintain. Energy is reported to be the largest single expense for desalination plants , accounting for as much as half of the costs to make drinking water from the sea viable. There costs of desalination are not just monetary but environmental as well. Sea life can get sucked into desalination plants, killing small ocean creatures like baby fish and plankton, upsetting the food chain.
Also, there is concern of what happens to the separated salt, which is left over as a very concentrated brine. However, the energy used to provide enough desalinated water for the daily use for a family of 4 is the same amount of energy needed to run an air conditioner for just 1 hour. Our desalination plants meet stringent environmental protection criteria and are designed to have minimal impact on the surrounding environment. Our 2 desalination plants are located near the open ocean.
Due to the high energy swell, the concentrated seawater discharged during the process mixes very quickly with the surrounding seawater. The offshore discharge and intake pipelines are designed and located to minimise any effects on sensitive marine habitats, such as seagrasses and reef systems.
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