Reverse Osmosis
works by using a high-pressure pump to increase the pressure on the salty side
of the RO and force the water across the semi-permeable RO membrane, leaving
almost all (around 95% to 99%) of dissolved salts behind in the reject stream.
The amount of pressure required depends on the salt concentration of the feed
water. The more concentrated the feed water, the more pressure is required to
overcome the osmotic pressure.
The desalinated water that is demineralized or
deionized, is called permeate (or product) water. The water stream that carries
the concentrated contaminants that did not pass through the RO membrane is
called the reject (or concentrate) stream.
As the feed water enters the RO membrane under
pressure (enough pressure to overcome osmotic pressure) the water molecules
pass through the semi-permeable membrane and the salts and other contaminants
are not allowed to pass and are discharged through the reject stream (also
known as the concentrate or brine stream), which goes to drain or can be fed
back into the feed water supply in some circumstances to be recycled through
the RO System Installation to
save water. The water that makes it through the RO membrane is called permeate
or product water and usually has around 95% to 99% of the dissolved salts
removed from it.
It is important to understand that an RO system employs
cross filtration rather than standard filtration where the contaminants are
collected within the filter media. With cross filtration, the solution passes
through the filter, or crosses the filter, with two outlets: the filtered water
goes one way and the contaminated water goes another way. To avoid buildup of
contaminants, cross flow filtration allows water to sweep away contaminant
build up and also allow enough turbulence to keep the membrane surface clean.
What contaminants
will Reverse Osmosis remove from water?
Reverse Osmosis is
capable of removing up to 99%+ of the dissolved salts (ions), particles,
colloids, organics, bacteria and pyrogens from the feed water (although an RO
system should not be relied upon to remove 100% of bacteria and viruses). An RO
membrane rejects contaminants based on their size and charge. Any contaminant
that has a molecular weight greater than 200 is likely rejected by a properly
running RO system (for comparison a water molecule has a MW of 18). Likewise,
the greater the ionic charge of the contaminant, the more likely it will be
unable to pass through the RO membrane. For example, a sodium ion has only one
charge (monovalent) and is not rejected by the RO membrane as well as calcium
for example, which has two charges. Likewise, this is why an RO system does not
remove gases such as CO2 very well because they are not highly ionized
(charged) while in solution and have a very low molecular weight. Because an RO
system does not remove gases, the permeate water can have a slightly lower than
normal pH level depending on CO2 levels in the feed water as the CO2 is
converted to carbonic acid. Reverse osmosis system
is very effective in treating brackish, surface and ground water for both large
and small flows applications. Some examples of industries that use RO water
include pharmaceutical, boiler feed water, food and beverage, metal finishing
and semiconductor manufacturing to name a few. Hometechsd Company
has the best service provide to their clients. Call (619) 436 6294 now for free no-obligation estimates.
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