Reverse osmosis is a new membrane separation technology developed
in 60s. It is a membrane separation technology which uses pressure
difference as its motive force. Originally it develops from
American space navigation in 1960s and it is for civil use in
various fields, such as scientific research, pharmaceutical
industry, food industry, beverage industry, desalination of sea
water, etc.. However, ultrapure water for industrial use, such as
fields of electron, electric power, chemical, electroplating and
boiler, is usually used as primary treatment of deionization or
EDI. Compared with traditional technology using ion exchange resin
as primary treatment, reverse osmosis has advantages of low cost,
energy saving, steady operation and purer water outflow and it
greatly extends the regeneration period of post-stage ion exchange
resin and cleaning period of EDI.
Osmosis is a physical phenomenon. When two kinds of salty water
with different concentration is separated by a semi-permeable
membrane, it is easy to find that water with low level of salinity
will permeate membrane into water with high level of salinity, but
the salt is remained. Therefore, it gradually makes the
concentration of two kinds of water blend evenly. This process is
called natural osmosis. Reverse osmosis is a separation method
which separates solute and solvent of solution under pressure drive
by the selection and trapping effect of semi-permeable membrane.
Reverse osmosis equipment is a set of water treatment system based
on reverse osmosis membrane. A complete set of reverse osmosis
system is composed by pretreatment part, reverse osmosis host
machine(membrane filtration part), after treatment part and
1. Pretreatment system is consisted of quartz sand filtration
device, activated carbon filtration device and precise filtration
device with the main purpose of removing sand, rust, colloidal
substance, suspended solids, pigment, smell and biological organic
matter in raw water and decreasing remaining ammonia value and
harmful substance, like pesticide pollution. If the quantity of
calcium and magnesium in raw water is high, soft water device is
needed, so as to protect post-stage reverse osmosis membrane from
damage by large particles and extend service life of reverse
2. Reverse osmosis host machine, as core of whole water treatment
system, is composed by blower pump, putamen, reverse osmosis
membrane and controlling circuit, which decides the quality of
outflow water. As long as proper model of membrane and blower pump
is used, the salinity filtering capacity of reverse osmosis host
machine can be up to and over 99% and conductivity of outflow water
can be within 10us/cm(25°).
3. After treatment mainly processes on pure water made by reverse
osmosis host machine. If connected with ion exchange or EDI
equipment, after treatment can produce industrial ultrapure water;
if used on civil direct-drinking water craft, it is connected with
sterilization device, such as ultraviolet germicidal lamp or ozone
generator, so as to make direct-drinking water.
4. In order to make sure reverse osmosis equipment operates
normally and to extend service life of reverse osmosis membrane
unit, it needs cleaning after certain period of operation to remove
dirt, such as calcium carbonate, metallic oxide, biological growth
(germ, fungus, mould), etc.
ⅣFeatures and Application
Reverse osmosis membrane separation technology applies principle of
reverse osmosis membrane to realize separation and it has following
Under circumstance of normal temperature and no phase change, it
can process separation of solute and water. It is applicable for
separation and concentration of heat-sensitive substance. Compared
with separation method of phase change, it is lower energy
Reverse osmosis membrane separation technology can remove a wide
range of impurities.
With high desalination rate and water reuse rate, it can trap
solute of several nanometers.
It applies low pressure as its membrane separation driving force,
therefore the separation device is easy and safe to operate,
maintain and control.
As a result, reverse osmosis water treatment technology is widely
used in fields of boiler water supply, ultrapure water treatment of
electron and semiconductor, pure water treatment of chemical and
pharmaceuticals, food, drinks, drinking water, sea water,
metallurgy, light industry, electroplating and leather industry.