The presentation discusses desalination, a process used to convert seawater into potable water, highlighting methods such as reverse osmosis, multistage flash, electrodialysis, and vacuum freezing. While desalination addresses water scarcity, especially in dry regions, it is noted to be expensive, with some areas experiencing higher costs than gasoline. The Shoaiba desalination plant is mentioned as the world's largest, producing 450,000 m3/day at a total cost of $1.06 billion.

1. Presentation
on
Desalination
School Of Architecture And Planning
Graphic Era Hill University
By
Sonali Jain I Anmol Taneja I Hatim Ali I Atul Tiwari

2. Contents
•Introduction
•Why desalination
•What is desalination?
•Natural desalination ( water cycle )
•Artificial desalination
• Reverse osmosis
• Multistage flash
• Electrodialysis
• Vacuum freezing
•System diagram
•Shioba desalination plant

3. Introduction
•Many regions in the world do not have easy access to fresh
drinking water
•Desalination process helps remove salts from sea water to
make it drinkable
•Pros: Brings drinking water to many dry regions
•Cons: Expensive
•In some parts of Middle East, a liter of water is more
expensive than a liter of gasoline

4. 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
Image source: Microsoft
clip art

5. What is
desalination?
•The process of removing salt from sea water.
•It extracts mineral components from saline water.
•The chemical process of changing seawater into potable or
freshwater is called desalination.

6. Natural Desalination:
Water Cycle!• Major Stages
• 1. Evaporation
• 2.Condensation
• 3.Precipitation
• 4. Collection

7. Image source: http://ga.water.usgs.gov/edu/drinkseawater.html

8. Artificial Desalination
Methods
•Reverse Osmosis
•Distillation
• Multistage flash (MSF)
• Vapor compression
•Electro dialysis
•Vacuum freezing Image source:
http://ga.water.usgs.gov/edu/drinkseawater.

9. Reverse Osmosis
•Water pressure increased
•Pumped through permeable membranes
•Salts separated from water due to membranes
•Most Desalination plants utilize this technology

10. Image source:
http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageServ
ice.svc/ImageService/Articleimage/2007/EM/b708455m/b708455m-f1.gif
Reverse Osmosis

11. Reverse
Osmosis
Image source: http://puretecwater.com/images/Reverse-Osmosis-Color.png

12. Multi Stage flash
•Steam is used to heat tubes of saline water
•Heated water flows into “stages” that are at lower pressure
•Water boils rapidly and “flashes” into steam

13. Multi Stage flash
Image source:
https://danangnugroho.com/wp-content/uploads/blogger/-
MKfu_21nRfs/Ur06DEKsihI/AAAAAAAAAjM/i0A-lRad2Iw/s1600/MED.png

14. Multi Stage flash (cont…)
•Generally, only a small amount
converts to steam since rapid
vaporization results in cooling of
water
•Thus water is flashed multiple
times in different stages at lower
pressures, requiring no extra
heat
•But, multi stage flashing reduces
thermal efficiency
•85% of world’s desalinated
water is generated through MSF
Image source:
http://ga.water.usgs.gov/edu/drink
seawater.html

15. Electrodialysis
•It is used to transport salt ions from one solution through
ion exchange membranes to another solutions under the
influence of an applied electrical potential difference.
•The cell consists of dilute compartment formed by an anion
exchange membrane and a cation exchange membrane
placed between two electrodes.

16. Electrodialysis
Image source: http://puretecwater.com/images/Electrodialysis.png

17. Vacuum freezing
•In physical chemistry , ice crystals are formed are made up
of essentially pure water when the temperature of saline
water is lowered to its freezing point and further heat is
removed.
•It is the nature of all the crystals that impurities are excluded
from the structures of the crystals as they grow.
•It requires the separation of ice crystals from the brine ,
cleaning of ice crystals to remove the adhering salts , and
then melting of the crystal to form pure water.

18. Vacuum freezing
Image source: http://puretecwater.com/images/Vacuum-freezing.png

19. System diagram
evaporator
condenser
membrane
evaporator
condenser
saltwater
vapor
brine
vapor
waste tank
clean water
water
water
drinking
water
brine
brine
Image source: flow chart created by Juan Ramirez jr ., ITL program , college of engineering
University of Colorado at Boulder, 2009

20. Systems and System
Diagram
• System: An object that receives inputs and transforms
them into outputs
System diagram: A block diagram that describes operation of
a system
Example: This plant uses two evaporators and
condensers along with a membrane filter to clean
saltwater (follow the arrows though the diagram)

21. Shoaiba Desalination Plant
•Largest desalination plant in the world
•Produces 450,000 m³/day
•Per year
• 150 million m³ of water is
desalinated
• Total cost is $1.06 billion
•To increase the thermal efficiency of this plant, the
maximum number of stages is set to 25 (MSF)
•Research in the field is resulting in more plants coming up in
Florida and California

22. Shoaiba Desalination Plant
Image source:
http://www.water-technology.net/uploads/project/shoaiba-desalination/images/shoaiba1.jpg

23. Thank
You