Desalination Lecture Notes PDF

The Institution of Excellence in Technical and Vocational Education and Training www.udst.edu.qa Prepared by: Dr. Kishwar Ali, Version 3 Science & the Environment (SCIE 1002) Week 13: Environmental Issue: Desalination Human Population Growth Lecture: 12 This Photo by Unknown Author is license...

The Institution of Excellence in Technical and Vocational Education and Training www.udst.edu.qa Prepared by: Dr. Kishwar Ali, Version 3 Science & the Environment (SCIE 1002) Week 13: Environmental Issue: Desalination Human Population Growth Lecture: 12 This Photo by Unknown Author is licensed under CC BY-NC This Photo by Unknown Author is licensed under CC BY Prepared by: Dr. Kishwar Ali, Version 3 Understand what is Desalination; • What is the need of it? • Introduction to the process of desalination and different types of plants; • Global distribution of desalination plants and issues with desalination • Cost of desalination and possible solutions or alternatives APPROACH TO WATER ISSUES •Water is needed for a number of end-uses: • drinking water • agriculture • power plants • industrial processes • sanitation •Optimal solutions can be obtained through a systems approach that integrates consideration of various enduses, their energy requirements, and their associated economic and environmental costs SOME INTERESTING PERSPECTIVES • “Many of the wars in this century were about oil, but wars of the next century will be about water.” (Ismail Serageldin, Vice President, World Bank, 1996) • “The next war in the Middle East will be over water, not politics.” (Boutros Boutros-Ghali, Secretary General, United Nations, 1991) BASIC FACTS: HEALTH ISSUES • More than a billion people lack access to safe drinking water • About 4 million children below age 5 die each year from waterborne diarrheal diseases (400 per hour) • About 60 million children annually reach maturity stunted due to severe nutrient loss/complications from multiple diarrheal episodes • About 1 billion people boil their drinking water at home A SIMPLE MESSAGE • How to deal with water issues will be a major global concern in the 21st century • An important part of addressing water issues is having the energy needed to transport, treat or desalinate water resources • A systems approach (e.g., addressing water needs on a regional basis) can produce optimal solutions • Water and energy are key components of sustainable economic development, and are inextricably linked Water Desalination Obtaining reliable fresh water supplies from challenging water sources Fresh Water Needs Economic expansion Agriculture and food Public health Quality of life Why Desalination? 75% of the Earth’s surface is covered by water 97.5% of that water is oceans Only 1% is available for drinking 80 countries suffered from water scarcity by the mid-1990s 1.5 billion people lack ready access to drinking water Show video at: http://www.gewater.com/images/multimedia/desal/index_flash.html Can we drink salt water? The Rime of the Ancient Mariner Water, water, everywhere And all the boards did shrink Water, water, everywhere Nor any drop to drink -Samuel Taylor Coleridge Small quantities are not harmful, but it is counterproductive (it just makes you more thirsty!) Eventually, it can be dangerous, ultimately producing fatal seizures, heart arrhythmias and kidney failure Natural Desalination: Water Cycle! Major Stages 1. Evaporation 2. Condensation 3. Precipitation 4. Collection Desalination Technologies 1. Thermal Desalination Processes Similar to the Earth’s natural water cycle Water is heated, evaporated and collected Produces clean water and brine Example: Multi-Stage Flash Desalination  Process uses multiple boiling chambers kept at different atmospheric pressures  Saltwater enters the system and is boiled and evaporated in each chamber  Process produces clean water and brine Desalination Technologies 2. Membrane Desalination Processes  Saltwater is forced through membrane sheets at high pressures  Membrane sheets are designed to catch salt ions  Process produces clean water and brine Example: Reverse Osmosis  Saltwater is forced through a membrane at 600 to 1000 psi  Multiple layers of membranes remove as many of the salt ions as possible Desalination Plants around the World Jabel Ali Desalination Station in Dubai  Capacity: 140 million gallons per day  Opened June 2010 More Desalination Plants Abu Dhabi, United Arab Emirates (3) Aruba (1) Australia (3 in use, 3 under construction, 1 planned) Cyprus (1) Israel (3 in use, 2 under construction) USA  Yuma (Arizona), opened 1992  El Paso (Texas) opened 2004  Tampa Bay (Florida) opened 2007  Monterey (California), in the planning stages Republic of Trinidad and Tobago (1) Systems and System Diagrams System: An object that receives inputs and transforms them into outputs  System diagram: A block diagram that describes operation of a system water vapor membrane condenser drinking water clean water saltwater vapor evaporator brine condenser water evaporator brine brine waste tank Example: This plant uses two evaporators and condensers along with a membrane filter to clean saltwater (follow the arrows though the diagram) Desalination Argument Outline 1. Global Water Crisis 2. Success so far 3. Economics 4. Marketable byproduct Global Water Crisis: Demand for Desalination http://www.toonpool.com/cartoons/World%20fresh%20water%20supply_31345 Availability of Freshwater • 97.5% of the water on earth is in the ocean. • Only 2.5% freshwater • 70% is permanently frozen in glaciers • 30% is groundwater • 0.3% is in rivers and lakes UN Water, 2011 http://www.unwater.org/statistics.html Freshwater Demand by 2025 Scientific American, August 2008 By 2025… Freshwater demand will rise by 2/3 1.8 billion people will be living in countries or regions with absolute water scarcity, and 2/3 of the world population could be under stress conditions. Water withdrawals are predicted to increase by 50% in developing countries, and 18% in developed countries. Science, Aug. 2011 United Nations Water Statistics, 2011 http://www.munnaontherun.com/2008/06/water-crisis.html Desalination  Unlimited, steady supply of high-quality water, without impairing natural freshwater ecosystems. Image: http://www.good.is/post/seawater-our-only-hope-for-a-drink/ Desalination Today • Nearly 15,000 desalination plants today • Provide some 300 million people with water • Still less that 2% of total planetary water consumption Explosion of demand in the Middle East and North Africa region Also widely employed in Spain, the Caribbean, and Australia New markets are growing in China, India, Singapore, Chile, and the USA Case Studies • There are already 14,451 desalination plants in use world wide • These plants produce 59.9 million cubic meters of water per day (15.8 billion gallons of water) • Information: the International Desalination Association as of 2009 Co-generation • Co-generation uses “duel purpose facilities to produce both electricity and water” • Also called CHP for Combined Heat and Power • Excess heat from power production is incorporated into the process of thermal water desalination • Fossil fuels or nuclear power are often used with desalination plants in the Middle East and North Africa Source: New World Encyclopedia Thermal/Multi Stage Flash • Thermal: heated water to boiling point, condensation (pure water) is collected at the top and impurities left behind Reverse Osmosis/Membrane • Intake system  Membrane Process  Pre-treat water  Reverse Osmosis membrane  Post Treatment  Pictures from International Desalination Association video Nuclear Desalination • There have been over 15 years of experience with nuclear desalination, mainly in India, Japan, and Kazakhstan • In Japan, 8 nuclear reactors are linked to 10 desalination plants • India: hybrid Nuclear Desalination Demonstration Project (NDDP) Source: World Nuclear Association World Desalination Plants Economics • Increase in technology such as improvements in the use of membranes are increasing efficiency and reducing cost http://hbfreshwater.com/desalination-101/desalination-worldwide • Decreasing the use of energy consumption over time is reducing the cost of operation http://hbfreshwater.com/desalination-101/desalination-worldwide • Decrease in cost leads to a decrease in price making freshwater more affordable www.tandfonline.com/loi/venv20 • Outstanding career opportunities for professionals engaged in water industry, science or engineering. • IDA’s Young Leaders Program • Provide a forum for communication, networking and exchange of ideas among these emerging leaders and the industry at large. Example: Australia • Desalination will provide a secure and predictable supply of freshwater to places such as Australia, who's other source of freshwater is capturing rain water which is highly variable and infrastructure intensive • Australia has already implemented this technology successfully, utilizing 3 in-use plants, 3 in progress plants and 1 planned plant By-Product A Marketable By-Product Seawater Intake Precautions • The impact on a population level is not clear given the naturally high mortality of larval organisms in marine ecosystems. • Appropriate screens and low intake velocity on open surface intakes can minimize impingement. • Locating intakes away from biologically productive areas can substantially reduce or eliminate entrainment of small planktonic organisms. • Underground beach wells Menachem Elimelech, et al. Science Aug. 2011 Brine Impact • In the planning phase for Israel’s Ashkelon desalination facility there were concerns about the impact of the brine that the desalination process produces • Discharged 1km into the sea • Residual dilution • Diffuser above seabed • Effects: • Minimal salinity change • Creation of a positive “mini-fishery” microenvironment Tal, Alon. Environmet: Science and Policy for Sustainable Development Precipitation http://www.scientificamerican.com/article.cfm?id=freshwater-crisis-current-situation UNEP: United Nations Environment Program http://www.theglobaleducationproject.org/earth/fresh-water.php?format=print Cost • It is true that desalination may be expensive today, but it is a long term solution to the water crisis and as shown, over time the cost will decrease • It is possible for the desalination plant to run of renewable energy such as solar or wind for example in Perth, Australia, the plant runs on renewable energy from a nearby wind farm. The increased use of renewable energy will reduce the carbon foot print in Australia Cost • It is hard to actually predict the cost of a desalination plant because there is little available information • Cost is determined by a lot of different factors such as the capital and operating costs, type of facility, location, feed water, labor, energy, financing, and concentrate disposal which also makes the cost hard to predict Cost • Much of the energy use associated with desalination can ultimately be recovered and recycled further lower the cost Solutions or alternatives to desalination • Water conservation, conserving the currently available fresh water resources. • Water use efficiency, use the available water efficiently. • Storm water capture and reuse, Storm waters and fresh waters could be captured and reused, • Recycling water is proven to be an effective strategy to increase regional water supplies and often cost less than desalination. • In addition, these alternatives provide pollution abatement, habitat restoration, and flood control benefits, which are commonly overlooked during cost/benefit assessments. • For desalination practices, clean energy sources should be utilized, like solar, wind or tidal energy which will reduce the impact of carbon emission in the process. • If desalination is pursued as a freshwater source, it must use the best available technology to minimize marine life impacts. References • Thirsty? How ‘bout a cool, refreshing cup of seawater?, USGS Water Science for Schools, Updated March 29, 2010. U. S. Geological Survey, U.S. Department of the Interior. Accessed May 1, 2010. http://ga.water.usgs.gov/edu/drinkseawater.html • Texas A&M AgriLife: Texas Water. Texas A&M University. Water Resources Education. Accessed May 1, 2010. http://texaswater.tamu.edu/ • Wikipedia.org, Wikipedia Foundation Inc., Accessed May 1, 2010. (Source of vocabulary definitions with some adaptation.) http://wikipedia.org • Desalination, Existing facilities and facilities under construction. Wikipedia: the free encyclopedia. Accessed May 29, 2010. http://en.wikipedia.org/wiki/Desalination Image sources Cow: http://www.ars.usda.gov/is/graphics/photos/dec04/k11662-1.htm Wheat: http://en.wikipedia.org/wiki/Wheat Farm: http://www.ars.usda.gov/is/graphics/photos/sep09/k5052-5.htm City : http://www.ars.usda.gov/is/graphics/photos/may02/k5369-5.htm Boat: http://en.wikipedia.org/wiki/File:Amerigo_vespucci_1976_nyc_aufgetakelt.jpg Sonoran desert soil: http://en.wikipedia.org/wiki/File:Drought.jpg Girl with hose: Microsoft clipart  Ocean: Microsoft clipart Image sources Thermal desalination process animation: http://ga.water.usgs.gov/edu/drinkseawater.html Desalination plant photo: http://ga.water.usgs.gov/edu/drinkseawater.html Water cycle diagram: http://ga.water.usgs.gov/edu/watercycle.html Membrane diagram created by Juan Ramirez Jr., ITL Program, College of Engineering, University of Colorado at Boulder, 2009 Flow chart created by Juan Ramirez Jr., ITL Program, College of Engineering, University of Colorado at Boulder, 2009 Byproduct references • http://www.water-technology.net/projects/tampa/ • http://www.desalination.biz/ • http://www.desware.net/ Any Questions ? Thank you +974 4495 2222 [email protected] Location University of Doha for Science & Technology 68 Al Tarfa, Duhail North P.O. Box 24449 Doha, Qatar