RO. System

Understanding Reverse Osmosis:-     Reverse osmosis, commonly referred to as RO, is a process where you demineralize or demonize water by pushing it under pressure through a semi permeable reverse osmosis membrane.
Osmosis:-
Osmosis:- To understand the purpose and process of Reverse Osmosis you must first understand the naturally occurring process of Osmosis.
Osmosis is a naturally occurring phenomenon and one of the most important processes in nature. It is a process where a weaker saline solution will tend to migrate to a strong saline solution. Examples of osmosis are when plant roots absorb water from the soil and our kidneys absorb water from our blood.
Below is a diagram which shows how osmosis works. A solution that is less concentrated will have a natural
tendency to migrate to a solution with a higher concentration. For example, if you had a container full of water with a low salt concentration and another container full of water with a high salt concentration and they were separated by a semi--‐permeable membrane, then the water with the lower salt concentration would begin to migrate towards the water container with the higher salt concentration.

How does Reverse Osmosis work?

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.
In very simple terms, feed water is pumped into a Reverse Osmosis (RO) system and you end up with two types of water coming out of the RO system: good water and bad water. The good water that comes out of an RO system has the majority of contaminants removed and is called permeate. Another term for permeate water is product water – they mean the same thing. Permeate is the water that was pushed through the RO membrane and contains very little contaminants.
The ‘bad’ water is the water that contains all of the contaminants that were unable to pass through the RO membrane and is known as the concentrate, reject, or brine. All three terms (concentrate, reject, and brine) are used interchangeably and mean the same thing.
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 concentrate 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 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 a different route. To avoid build up 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 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. 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 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.