Desalination
Reverse Osmosis System / Desalination RO SystemWe are offering Desalination R O Plant and Water Reverse Osmosis Systems, these Desalination is a separation process used to reduce the dissolved salt content of saline water to a usable level. In reverse osmosis water purification systems and all desalination processes involve three liquid streams: the saline feed water (brackish water or seawater), low-salinity product water, and very saline concentrate (brine or reject water).
The saline feed water is drawn from open sea or underground beach
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 use of desalination overcomes the paradox
faced by mankind, that of having access to a practically
inexhaustible supply of saline water but having no way to use it. 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 of 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.
Technical Description
In the water reverse osmosis systems and 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 System consists of four major components/processes: (1) Pretreatment, (2) Pressure Boosting, (3)
Membrane separation, and (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.
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