How is the Reverse Osmosis Process Carried Out?

Reverse Osmosis, also commonly termed as RO, is the process of demineralization or deionizing by pushing the water through a semipermeable Reverse Osmosis Membrane.

To understand the purpose, process, and linkage of RO to the industrial water treatment systems, you must first understand the naturally occurring process of Osmosis.

Read on to get a clear picture of the process.


Osmosis is one of the most significant naturally occurring phenomena of nature. It is the cycle where a weaker saline solution tends to migrate to a robust solution. The most common example of Osmosis is ‘roots absorbing water from the soil’ or ‘nephrons absorbing water from our blood’.

For instance, imagine you have a container that has two moulds separated by a semipermeable membrane. You have poured water with a low salt concentration on one mould, while the other is full of water with a high salt concentration.

Next, the water with a lower salt concentration would begin to migrate towards the water with the higher salt concentration.

Reverse Osmosis

Reverse Osmosis is precisely the reverse of the whole osmosis process. While Osmosis occurs naturally, reverse Osmosis requires applying energy to the more saline solution.

In this case, the semi-permeable membrane that allows the passing of only water molecules and not dissolved salts, organic, etc., requires a push by applying pressure to desalinate water in the process.

How does Reverse Osmosis work?

Reverse Osmosis functions by using pressure pumps. This increases the pressure on the salt side of the RO and gorges the water through the semipermeable membrane. The process vacates almost all of the dissolved salts behind in the rejected cascade.

The amount of pressure required here depends on the same concentration of the water. The more the salt concentration, the more the pressure needed to overcome the osmotic pressure.

The desalinated water is called permeated water, or the final product. At the same time, the stream carrying the concentrated contaminated water that didn’t pass through the RO membrane is called the reject stream or concentrate stream.

As the feedwater enters the RO membrane through pressure, the water molecules are pressured to pass through the semipermeable membrane. This membrane refrains the salts and other contaminants to pass through. This refrained water is discharged through the reject or concentrated stream, which, in some circumstances, are feedback to the water supply to be recycled through the RO system to save water.

After the whole process, the water that makes it through the RO membrane is called permeate or product water. This usually has 95% to 99% of dissolved salts removed from it.

This is one of the most used techniques of Membrane Systems Australia.


It is significant to comprehend that the RO system employs cross filtration rather than standard filtration. With cross filtration, the process is carried out using two outlets, where the filtered water passes through one way while the contaminated remains are passed through the other way.

To overcome the rising issue of contaminated water, RO is the best strategy to include in the industrial water treatment systems.

Christophe Rude
Christophe Rude
Articles: 15839