reverse-osmosis

Reverse Osmosis - What can it do for you

Reverse osmosis is an older technology that was developed in the 1950s. The purpose of the technology is, unlike a carbon filter, to more or less eradicate all components in the water. This means that when the water has been treated in the system it "comes out on the other side" so pure that it does not actually contain anything other than its own molecules. Originally the idea was to extract drinking water from seawater, which to this day is still relevant.
We sell reverse osmosis systems both for the private household and for the industry.

Diffusion and osmotic pressure

A reverse osmosis system consists of a semipermeable membrane. This means that it is permeable to certain types of substances. The same membrane is found in plants. This makes it usable for reverse osmosis, where the desired result is to leave contaminants behind and let the clean water seep through. Membranes used for reverse osmosis are often made of polyamide, as this material has a high permeability to water and on the other hand it is impermeable to other substances such as salts and minerals, hence the name "semipermeable". 

To understand reverse osmosis, we need to explain the concept of diffusion. Diffusion is the movement of a substance from an area of high concentration to an area of low concentration; or in other words: they go from being assembled to being scattered so that the concentration is evenly distributed. A good example of this is having a jug of water, to which you add a quantity of red juice. After a while, you will see that the juice has distributed in the water, so that the particles of the juice are evenly represented in the entire amount of water.

In osmosis, as previously mentioned, we add a semipermeable membrane. Let us again imagine a jug of water in which we have added our membrane. In both sides of the jug we have a concentration of 10 water molecules. In this case, water will not flow through the membrane, as the concentration of water is the same on both sides.

Let us then assume that we have the same jug of water, where this time we have added 10 salt molecules in one side of the jug, so we have 10 water molecules in side 1 and 10 water and salt molecules, i.e. 20 molecules in total, in side 2. With the rule from diffusion, where we saw that the concentration goes from high to low, the water will thus increase in side 2, so that side 1 and side 2 will contain an equal distribution of water molecules. 

We have now explained osmotic pressure. When the water level rises in side 2 from the aforementioned example, the pressure also rises, which is what causes the water to rise, and thus we see that an osmotic pressure goes from a high to a low concentration of water; or that water will always seek to equalise its concentration by means of osmotic pressure, so that there are equal numbers of water molecules present on both sides.

Reverse osmosis - how the system works

In reverse osmosis, we want the water that passes the membrane to be 100% purified of various components. This is done by turning the rule of concentration upside down so that the water will change from a high concentration to a low concentration. Or put another way: We leave one side of the jug empty and fill it with water from the other side. In order for this to be possible, we must add a pressure that is higher than the osmotic pressure, because otherwise the water to be purified and which must end up on side 2 of the jug will run back through the membrane to equalise the number of water molecules. It is very common to use reverse osmosis for desalination of water, where a pressure higher than the osmotic pressure causes the water to seep through the membrane so that on the one side there is pure drinking water and on the other side there are various minerals, salt ions, etc.

What can the system be used for?

A reverse osmosis system can be used both in private homes but is also widespread in the industry, where clean water is a necessity. In industrial contexts, these systems are often needed in laboratories, nursery gardens, car washes, refrigeration systems, etc., where after using the water there must be no residues on the surfaces, which over time reduces the life of various devices.

In the private home, the system may, as mentioned previously in the article, be used to purify water, which can then be used as drinking water. If you are in doubt about whether you will benefit from an osmosis system in your home, please give us a call and we can discuss your needs.