Green Water Science Sea water desalination is a process using which dissolved minerals including salts are removed from the seawater. Despite water is a superabundant natural resource on the planet, but still the available clean drinking water is just only 0.3 percent of the world's total amount of water. The source of natural fresh water is limited so sea water can play and is playing important role to meet the drinking water demand. However, the sea water before use must be treated (desalinated) which is not an easy task.  Seawater can be desalinated using various techniques and methods. Distillation is a primary technique used for desalination. However, the process is energy intensive. "One t" of drinking water is obtained by using 620 kWh of evaporation enthalpy.

Reverse Osmosis Technology accounts for 85% of total installed desalination capacities. Though both thermal process (MSF,& MED) and membrane separation process are used worldwide but now trend is shifting towards membrane separation process. 

REVERSE OSMOSIS on the other hand, the energy demand can be reduced to 7 kWh. Other method that can be used is electro dialysis Lot of factors should be considered before choosing an appropriate technology. 

Desalination Capacity by Country
Following is the top five countries where maximum desalination plant is located. It is clear that maximum plant is located in Middle East as there is maximum crisis of water. The maximum desalination capacity is in Saudi Arabia followed by USA. Generally thermal process is followed in these regions however now due to advancement in membrane technologies they are too gaining popularity and their use is growing with a rapid pace.   

Country	Total Capacity (m/day)	% of Global Production	MSF	MEE	MVC	RO	ED
Saudi Arabia	5, 253,200	25.9	67.7	0.3	1.2	31	1.9
United State	3,092,500	15.2	1.7	1.8	4.5	78	11.4
United Arab Emirates	2,164,500	10.7	10.7	0.4	3.0	6.5	0.2
Kuwait	1,538,400	7.6	7.6	0.7	0.0	3.4	0.3
Japan	745,300	3.6	3.7	2.0	0.0	86.4	6.8

We Green Water Science design, supply and install Sea Water Desalination Plant/Brine Water/ Brackish Reverse Osmosis Systems. Our Desalination is a separation process used to reduce the dissolved salt content of saline water to a consumable level. In the current reverse osmosis water purification systems and all desalination processes involve three liquid streams: the saline feed water, low-salinity product water, and very saline concentrate; brine water.

The salty feed water is drawn from open sea or underground shore well sources. It is separated by the desalination process into the two output streams: the low-salinity product water and very saline concentrate streams. The Desalination process will help the world to overcome water scarcity and enhances the quality of their lives. In the past, the difficulty and expense of removing various dissolved salts from water made saline waters an impractical source of potable water. However, starting in the 1950s, desalination began to appear to be economically practical for ordinary use, under certain circumstances.

The product water after the desalination process is generally water with less than 500 mg/1 dissolved solids, which is suitable for most domestic, industrial, and agricultural uses. A by-product of desalination is brine. Brine is a concentrated salt solution (with more than 40,000 mg/1 dissolved solids) that must be disposed of, generally by discharge into deep saline aquifers or surface waters with a higher salt content. Brine can also be diluted with treated effluent and disposed of by spraying on golf courses and/or other open space areas.

Our Technical Description:
In the Reverse Osmosis water purification systems process, water from a pressurized saline solution is separated from the dissolved salts by flowing through a water-permeable membrane. The permeate (the liquid flowing through the membrane) is encouraged to flow through the membrane by the pressure differential created between the pressurized feed water and the product water, which is at near-atmospheric pressure. The remaining feed water continues through the pressurized side of the reactor as brine. The major energy requirement is for the initial pressurization of the feed water. For brackish water desalination the operating pressures range from 250 to 400 psi, and for seawater desalination from 800 to 1000 PSI.

A Desalination R O Systemconsists of four major components/processes:

(1) Pretreatment, (2) Pressure Boosting, (3) Membrane separation (4) Post-treatment stabilization.

Pretreatment : The incoming feed water is pretreated to be compatible with the membranes by removing suspended solids, adjusting the pH, and adding a threshold inhibitor to control scaling caused by constituents such as calcium sulphate.

Pressure Boosting : The pump raises the pressure of the pretreated feed water to an operating pressure appropriate for the membrane and the salinity of the feed water. Now a days, Energy Recovery Devices are used in tandem with Pressure Booster so as to cut down the energy costs.

Separation : The permeable membranes stops the passage of dissolved salts while permitting the desalinated product water to pass through. Applying feed water to the membrane assembly results in a freshwater product stream and a concentrated brine reject stream. Because no membrane is perfect in its rejection of dissolved salts, a small percentage of salt passes through the membrane and remains in the product water. Reverse osmosis membranes come in a variety of configurations. Most common now a days are Thin Film Composite.

Post Treatment : The product water from the membrane assembly usually requires pH adjustment and degasification before being transferred to the distribution system for use as drinking water. The disinfection is also done if the water is being used for drinking purpose.

• Thermal and Membrane Process
• Multiple Effect Distillation (MED)
• Reverse Osmosis (RO)
• Multistage Flash (MSF)
• Hybrid Configurations
• Salt Recovery
• Packaged Plants

 

 

Read More about Thermal Desalination