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Water Systems Science Project

Desalination
by

Adela Lin

on 7 March 2013

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Transcript of Water Systems Science Project

By: Adela, Anna, and Kassandra Science Project: Water Systems Desalination is any process that removes salt from water, producing pure, fresh drinking water. What is Desalination? The "Pros" The "Cons" 1. Seawater Intake
2. Filtration
3. Reverse Osmosis
4. Storage
5. Water Outlet Most Common Ways of Desalination Different Types of Desalination There are many ways of desalinating salt water. But even though all can successfully desalinize ocean water and make pure, fresh water, they’re all costly, and they all need high amounts of energy to make the process. Reverse Osmosis Reverse osmosis is when salt water is forced against membranes which only allow liquids, not solids, to pass through. It is also the most common way of desalinating water. The water flows against the membrane and leaves about 99.5% of the salt behind, leaving the water drinkable. So, it's very effective! Reverse osmosis have problems too though; when too much bacteria stays in the membrane, they have been known to clog up. Fortunately, this has improved from when it first started, so the membranes are more reliable. The saltwater moves past semi-permeable membranes to an area of high concentration ammonia salts, and leaves the sea salts on the other side of the membrane. After that, the ammonia salts are heated to evaporate and the salts are reused. The opposite of reverse osmosis? The next type of water desalination is...forward osmosis! This system is less costly than reverse osmosis because it uses up less energy. But the system is still fairly new and it needs more research and development before it is able to be put into full use. Forward osmosis is a process that does not force the water to desalinize, but allows it to naturally occur. It happens by moving the substance from a low area of concentration to a high area of concentration. And lastly, electrodialysis. Electrodialysis reversal is used to desalinize water by putting it though a membrane and creating an electric charge to separate the different ions in the water. The main drawbacks to using electrodialysis are the expensive costs to build the facility and the energy costs of using it. However, it is the most modern technology and is slowly improving as time goes by. Metal ions are on the positive side of the plate, and other ions, such as salt, are on the negative side. The ions on each plate can be removed, leaving fresh, pure water behind. This process may seem absolutely and amazingly perfect but as things always turn out, it is not. Waste Disposal Desalination uses pretreatment/cleaning chemicals, which need to be added to the water before it is desalinated. The cleaning chemicals include chlorine, hydrogen peroxide and hydrochloric acid. These chemicals can be used only for a specific amount of time, so when they are done with they have to be dumped which becomes a big environmental concern. Brine Brine is the left over salted water after desalination. This left over water has to some how be disposed, and what do you think most desalination plants do? This presents another environmental impact on our oceans. The very salted water causes a decrease of oxygen levels which causes animals and plants to suffocate. Ocean Pollutions On top of all the pollution of the water, the plants themselves suck up water which has animals, plants and eggs. This results in the plants being traps as it kills many organisms, many of which belong to endangered species. So the plants negatively effect the population of animals and other plants. THEY PUMP IT BACK INTO THE WATER. And that's not good. OTHER CONS: Energy consumption

Health Concerns Consider these statistics. 97% of Earth's water is sear water; the remaining 3% is fresh water, and less than 1% of this is accessible, the rest being trapped in the glaciers. The ocean is a reliable source of water, unlike rainfall, which sometimes falls and sometimes doesn't. The ocean is always there (at least, it will be for the next 50 years at least, according to scientists). And that is a good thing about desalination. It offers a secure source of water, the necessity for life. Desalination water is safe, free of chemicals and salt. It is not a radical new invention; there are more than 170, 000 plants in operation today. Also, desalination is environmentally friendly; it doesn't require chemicals, and does not spew out toxic waste. In fact, a UN environmental board conducted a study which revealed that the environmental impact of desalination is minimal if the process is used correctly. Others: Desalination plants serve as a very flexible means of water output, allowing for differing quantities of seawater to be processed according to the level of demand. The by-products of desalination can be used in salts, and can be marketed (this is a small market, yet it can create some profit). Geography of Desalination Desalination is currently used by countries that have an extreme need for fresh water, have enough money to fund it, and posses the amount of energy required to produce it. The Middle East holds the top spot for desalinated water, due to several countries’ large facilities, including Saudi Arabia, the United Arab Emirates, and Israel. Also large producers of desalinated water are: Spain, the United States, Algeria, China, India, Australia, and Aruba. The technology is expected to spread increasingly, particularly in the United States, Libya, China, and India. = Desalination Areas Saudi Arabia is currently the world's number one producer of desalinated water. They use multi-flash distillation (a type of desalination) in several large plants, providing water for many large cities, including the larges city, Riyadh. Future Options of Desalination Desalination is a process primarily done in developed countries with enough money and resources. If technology continues to produce new methods and better solutions to the issues that exist today, there would be a whole new water resource for more and more countries that are facing drought, competition for water, and overpopulation. Though there are concerns in the scientific world about replacing our current overuse of water with complete reliance on sea water, it would undoubtedly be at least an option for many people struggling to survive or maintain their standard of living. How is the technology currently being used? - In recent years, people have been trying to use nuclear water desalination plants
- These are very cost competitive with fossil fuels
- Due to efficiency, we mostly rely on fossil fuels today YouTube Desalination Animation What kind of impact is the technology having on our water systems? A positive impact would be that desalination helps fish living in saline water, by cleaning it and then putting it back into the water. Negative impacts? Desalination costs a lot of money to process, which can impact the economy. Another negative impact: some desalination plants use nuclear energy, which send low levels of radiation that affect the environment tremendously over time, including everyone and everything in it. How might the technology be used in the future? The U.S. wants to make the future of desalination to be used further to better meet the growing fresh water needs. In order not to put too much of an economical strain on the desalination area, we just need to find a cheaper, more effective way to desalinate water. Discoveries and technologies available or in development that can help improve desalination as it is now: In order to make desalination a better option, some improvements to this new technology can be made... 1. Make a desalination plant capable of running off of renewable energy. Solar energy is particularly clean and would be a reasonable solution to limit the plant's use of fuel. 2. Run desalinated water through a secondary filtering process, whereby boron (an element) and any other harmful materials can be removed. Lastly, in order for desalination to be a practical solution to the water shortage problem, the bring by-product (as discussed earlier in the presentation) must be disposed of in a way that is less damaging to the surrounding environment. If the brine could somehow be used for an alternate purpose, the desalination process would improve drastically. Works Cited "Water Desalination." About.com Geography. N.p., n.d. Web. 26 Feb. 2013. <http://geography.about.com/od/waterandice/a/Water-Desalination.htm>. Terry, Carrie. "The Disadvantages of Desalination." EHow. Demand Media, 05 Feb. 2010. Web. 26 Feb. 2013. <http://www.ehow.com/list_5961767_disadvantages-desalination.html>. YouTube. YouTube, n.d. Web. 26 Feb. 2013. <http://www.youtube.com/>. Thank you for for your attention! We hope you enjoyed our presentation! WARNING: Short electricity lesson coming up! Experiment pictures taken by Anna Lomonosova Collier, E. P., and J. F. Fulton. Water Desalination. Ottawa: Inland Waters Branch, Dept. of Energy, Mines and Resources, 1967. Print. Water Desalination: Proposals for a Costing Procedure and Related Technical and Economic Considerations. New York.: n.p., 1965. Print. "Thirsty? How 'bout a Cool, Refreshing Cup of Seawater?" Desalination: Drink a Cup of Seawater? N.p., n.d. Web. 06 Mar. 2013. <http://ga.water.usgs.gov/edu/drinkseawater.html>. Experiment Time! 1 3 2 4 5 6 Very clean!
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