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| Fig. 1: Aerial view of the Zarchin Desalination Plant on the Red Sea in Eilat, Israel (Source: Wikimeda Commons) |
People across the globe face water scarcity on the daily basis. Spending hours each day attempting to get enough water for their family or community has become their reality. Arid regions in Central and West Asia, and North Africa have less than 1000 m3/capita/year water availability. [1] There are noticeable discrepancies between the accessibility to fresh water in regions across the world. Some populations are suffering due to shortages of rainfall and year to year variability, while other communities are faced with greater percentages of categorized brackish water. Regardless of the specific circumstances, one theme can be traced throughout. Earth's resources are being utilized and becoming further scarce; however, Earth's population continues to grow and develop and needs adequate freshwater to support certain levels of life and development. There is a scarcity of current resources and a need for accessible water supplies. A current demand therefore exists for large scale solutions to provide fresh water to growing communities.
The water desalination process in simplification separates salts and other minerals from water. Water from sources including seawater, wells, surface water, and wastewater can be collected and converted into freshwater by the removal of dissolved salt and particles. A common technique utilized to achieve this fresh water result is reverse osmosis. Through this technique, concentrated saltwater solution is pressurized and filtered. Applied pressure forces water molecules to pass from salty seawater solution through a porous membrane to fresh water. In a typical desalination plant utilizing the reverse osmosis process, it is reported that 3-10 kWh of electricity would be required to produce one cubic meter of freshwater from seawater. [2]
The desalination process is not a new concept. It is based on nature's water cycle and has been a form of water treatment consistent throughout the years in smaller scales. Traveling populations utilized this process to a lesser degree on ships to convert the seawater they had available into potable water. However, while this process has been present and boasts a long history, the process as adapted for large-scale populations has been largely criticized in the past. Concerns focus around the process as energy intensive and costly, requiring large-scale facilities. These arguments have limited the capacity and use of this process globally.
However, due to dedicated funding and research presenting new advancements, the conversation surrounding this process has in turn shifted within the last decade. Edo Bar-Zeev, expert on biofouling, and colleagues developed a chemical-free system to capture microorganisms originating from the collected seawater that tend to block the membrane pores between the saltwater and freshwater. [3] This development diminishes the significant challenge and cost that cleaning those pores posed, and aids in making the water desalination process more cost-effective. The IDE company, responsible for Israel's adaptations, in addition to maintaining clean membranes for the reverse osmosis process (so less pressure is ultimately needed to push saltwater through the membranes) reduces energy consumption of the process by reusing waste heat. These and other technological adaptations have combined to make the desalination process more efficient and alter the narrative surrounding the implementation of this process.
Reports convey that Israel now receives 55% of its domestic water from the desalination process (see Fig. 1). [3] Furthermore, the International Desalination Association claims that 300 million people get water from desalination and this number continues to climb.The Carlsbad Desalination Plant was built in 2015 by IDE in San Diego, California. [3] IDE's efforts working to continue lowering the cost and further the environmental footprint of its water desalination plants are good news for the millions of people who have already been affected and for those populations who still need a viable process to fill the water gap. As technology continues to advance, the harvest of water from the ocean becomes more and more practical and a possible solution in helping the water scarcity that is a daily reality for many populating the Earth.
© Audriana Fitzmorris. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] F. R. Rijsberman, "Water Scarcity: Fact or Fiction?" Agr. Water Manage. 80, 5 (2006).
[2] M. S. Atab, A. J. Smallbone, and R. P. Roskilly, "An Operational and Economic Study of a Reverse Osmosis Desalination System For Potable Water and Land Irrigation," Desalination 397, 174 (2016).
[3] R. Jacobsen, "Israel Proves the Desalination Era Is Here," Scientific American, 29 Jul 16.
