1. By Seong Taek Bpang Mar/07/2011
Desalination A part of an alternative solution to meet the water in demand?
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By Seong Taek Bpang
Mar/07/2011

2. Table of Contents Definition/Back ground Operating process
Types of desalination
World trend
Issue of desalination
* Note that this slide is not necessary for weekly status meetings

3. Current Status of water
According to IDA
Fresh water is app 3% of world water deposit
Less than 30 % of the water, ground and surface water, are available for daily use within the 3 percent

4. Increasing demand and unreliable supply
Increasing population and water demand
The expected population growth is about 2.6 billion in next 45 years, and it would mostly be from developing countries according to the U.S. Census Bureau.
Unreliable supply
Due to the climate change and pollution, traditional method of collecting water is becoming unreliable.
Ex- Australia, a country relied on collecting rain fall water is now looking for alternatives such as desalination due to the drought and low rain fall
Ex- Southern California dependence of Colorado river.

5. Christopher Gasson of Global Water Intelligence (GWI)
“People do desalination when they run out of opportunities, and the problem is the world overall is running out of opportunities: groundwater is overexploited to the extent it’s becoming saline and unusable; rivers are being drained; new dams are becoming less and less viable [and] long-distance transfer is expensive and controversial.”

6. What is Desalination?
Desalination is the process of removing dissolved salt and other minerals from seawater to create freshwater
The fact that desalination requires sea water the construction of a plant is limited by location
Majority of desalination plants are operating and being built in middle eastern country and Pacific island

7. General Process diagram of Desalination Pant
Water feed
Pre treatment
Desalination Unit
Post treatment
Fresh water
brine
Filtering Large particles
Screening
Floatation
Sedimentation
coagulation
Chlorination
UV treatment
pH adjustment
CO2 absorption
Limestone (CaCO3)
pH adjustment
Chlorination
Re-mineralization

8. Varying post treatment according to application
Drinking water
Irrigation water
Process water
Sodium chloride
< 450 mg/L
SAR optimization
minimized
Calcium, Magnesium
Hardness 6-10oD pH
Boron
<0.5 mg/L (WHO) <1 mg/L (EU)
Crop dependent
Disinfection
Required
Not required

9. Different Types of desalination technology
Thermal desalination
Multi-stage flash (MSF)
Multiple-effect distillation (MED)
vapor-compression (VC)
Membrane desalination
Reverse Osmosis (RO)
Electro dialysis reversal (EDR)
Nano filtration
Membrane distillation
Others include Solar , and Geothermal desalination

10. Thermal desalination (Conventional)
Usually requires large amount of energy
Good combination with Power plant (Dual purpose)
Thermal Desalination plant can use thermal energy (Low grade energy) that has been exhausted from the power plant.
For MSF distillation process distillers are coupled with extraction condensing or back pressure steam turbine
Most of the desalination plant in middle eastern is dual purpose desalination plant to achieve low operating cost.

11. Multi stage flash desalination

12. Shoaiba MSF desalination plant in Saudi Arabia

13. Membrane desalination
Semi permeable membrane is used for processing water
Relatively lower energy consumption of Energy compared to thermal desalination
Driving force is supplied by a pump (Electricity)
Typical operating pressure of sea water reverse osmosis is 600~1000 psi
Typical operating pressure of brackish water is psi

14. Reverse Osmosis Osmosis Reverse Osmosis
What are the dependencies that affect the timeline, cost, and output of this project?

15. Spiral construction of membrane

17. World largest RO desalination plant in Saudi Arabia

18. Trend of desalination Plant
Membrane desalination is being favored over thermal desalination
Development of membrane technology
Increased durability of membrane
During 1980 and 1990 the life time of membrane was 2~3 y; life time of membrane these days are 7~7.5 y
Capacity of processing water per membrane
Increased efficiency of membrane
Typical efficiency of a membrane is reported to be 48%
Reduced cost of membrane production

20. Economic side of desalinated of water
Typical cost of desalinated water (1 m3 =264 gallon)
sea water desalting US $ /m3
brackish water desalting US $ / m3
Cost of traditional supply of water
US $ /m3
Desalinated water cost component
capital costs (%)
energy costs (%) other costs
(labor, chemicals, etc) (%)
Depending on the location desalinated water can be competitive with other sources of water

22. Comparison of the two type
MSF desalination
Benefits:
low operating cost when it is co-located with power plant
Relatively low quality of feed water compared to RO.
Cons:
High operating cost when sources of heat is not available
High rates of corrosion and scale formation
RO desalination
Benefits:
Low energy intense
(Reduced energy consumption)
High quality process water
Compact plant design
Cons:
Higher capital cost
Re-mineralization is needed
Comparison in terms of energy usage
Average thermal desalination produce 23.41kgCO2/m3
Average reverse osmosis would produce 1.78kgCO2/m3

23. Issues and Misconception of Desalination
Major concerns:
Effects of open water intake to marine life
Fish eggs
Fish larvae
Plankton
Pollution due to the brine
Highly concentrated brine water is denser than sea water
Increase in CO2 emission
Duplicate this slide as necessary if there is more than one issue.
This and related slides can be moved to the appendix or hidden if necessary.

24. Efforts in conserving environment
Redesigning intake pipe and discharge pipe
Offshore intake
Sub sea bed intake
Passive intakes
Use of an alternative energy sources for desalination plant
Majority of the desalination plant in Australia is Wind powered
Saudi Arabia, a world’s largest producing country is investigating use of solar powered desalination plant.
More energy efficient design
Combining technology's of both thermal and Membrane
Outfall pipe
Multi port diffusor
Blending with cooling tower water

25. Growing industry
As of year 2007, approximately 7,500 desalination plants are operating world wide.
60 % of the plants are located in Middle East
Desalination industry is growing 10 to 15 % on average per year

26. World wide desalination water production

27. Questions?

28. References