Methods

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Multi Stage Flash Distillation

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In this process, water is evaporated and separated from sea water through flash distillation.[1] Each subsequent flash process utilizes energy released from the condensation of the water vapor from the previous step.[1]

Multiple Effect Distillation

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MED works through a series of steps called “effects”.[1] Incoming water is sprayed onto horizontally or vertically orientated pipes which is then heated to generate steam; the produced steam is then used to heat the next batch of incoming sea water.[1]. (Horizontally orientated tends to be more common).[1] [2] Steam used to heat the sea water can also be taken from nearby power plants to make it more efficient.[1] Although seen as the most thermodynamically efficient, a few limitations exist such as a max temperature and max number of effects.[2]

Vapor Compression Distillation

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By using one of two methods: a mechanical compressor or a jet stream, vapor is compressed and then used to provide the heat needed for the evaporation of the sea water.[1] Although the system requires only power, it is more efficient if kept at a small scale.[1]

Freezing

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Freezing involves partially freezing the sea water and removing the ice to then clean them and melt them back down into sea water.[1] In the freezing process, water is separated from the salt in order for the water to crystallize properly.[1]

Solar Evaporation

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Solar evaporation mimics the natural water cycle, in which the sun heats the sea water enough for evaporation to occur; after evaporation, the water vapor is condensed onto a cool surface.[1]

Electrodialysis/ Electrodialysis Reversal

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Instead of moving the water through membranes like reverse osmosis, electro dialysis requires the use of electric potential to move the salts through membranes.[3]

Other Issues

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Due to the nature of the process, there is a need to place the plants on approximately 25 acres of land on or near the shoreline.[4] In the case a plant is built inland, pipes will have to be set down to allow for easy intake and outtake.[4] If laid, however, the pipes will also have a probability of leaking into, and contaminating, nearby aquifers.[4] Aside from environmental risks, the noise generated by certain types of desalination plants can be loud.[4]

References

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  1. ^ a b c d e f g h i j k Khawaji, Akili D.; Kutubkhanah, Ibrahim K.; Wie, Jong-Mihn (March 2008). "Advances in seawater desalination technologies". Desalination. pp. 47–69. doi:10.1016/j.desal.2007.01.067. {{cite web}}: Missing or empty |url= (help)
  2. ^ a b Al-Shammiri, M.; Safar, M. (November 1999). "Multi-effect distillation plants: state of the art". Desalination. pp. 45–59. doi:10.1016/S0011-9164(99)00154-X. {{cite web}}: Missing or empty |url= (help)
  3. ^ Van der Bruggen, Bart; Vandecasteele, Carlo (June 2002). "Distillation vs. membrane filtration: overview of process evolutions in seawater desalination". Desalination. pp. 207–218. doi:10.1016/S0011-9164(02)00259-X. {{cite web}}: Missing or empty |url= (help)
  4. ^ a b c d Einav, Rachel; Harussi, Kobi; Perry, Dan (February 2003). "The footprint of the desalination processes on the environment". Desalination. pp. 141–154. doi:10.1016/S0011-9164(02)01057-3. {{cite web}}: Missing or empty |url= (help)