WHAT IS REVERSE OSMOSIS?

Posted by Filter For Fridge on May 21st, 2019

Reverse Osmosis : In this article we will explain what is and how reverse osmosis works. Before we explain what reverse osmosis is, we need to explain what osmosis is . In a nutshell, osmosis is called the passage of solvent molecules (eg water), through a semi-permeable membrane, from the solvent to the solution, or from a lower concentration solution (less) to a higher concentration (denser) solution.

Semi-permeable membrane (or osmosis membrane) is a membrane that allows solvent molecules (eg water) to pass through its pores and prevents the solute molecules from penetrating it. The semipermeable membranes may be natural (e.g., cell membrane) or synthetic (e.g., cellophane). Such films have all of themdomestic reverse osmosis water filters .

In order to better explain the phenomenon of osmosis we will need the help of the following picture, where two cases of solutions separated by semipermeable membrane are distinguished.

What is Reverse Osmosis?Suppose the solution (blue in the image) is sugar and has a C concentration (remember that sugar is dissolved in a clean solvent, ie water). On the left side (Side A) there is a clear solvent (water) with a clear concentration of C = 0 dissolved.

Remember that membranes allow only solvent molecules to penetrate it, so only pure water can penetrate the membrane. In the beginning, water runs faster from left to right, rather than from right to left. After a while, however, the concentrations will be equalized, ie the water going from left to right will run at the same speed as the water that goes from right to left.

The above procedure is called osmosis. Let's look at what is reverse osmosis now . If the right side (Side B) of the above picture exerts an external pressure greater than the osmotic pressure of the solution (ie Phex), then the phenomenon is reversed and solvent molecules will leave the solution to the pure solvent (or the denser to the most dilute solution, ie from right to left). This is reverse osmosis.

In essence, we push the dirty water to pass through the reverse osmosis membrane. Because, however, only clean water can penetrate the membrane, the rest of the water is thrown into the kitchen drain and we only drink the pure water that penetrated the membrane.

Until now, reverse osmosis has been the best technology for filtering water and desalinating seawater to tackle reedbeds. Several islands in the world use this technology to feed people. 

Press the sea water (right) to pass the semipermeable membrane of osmosis. So only clean water penetrates the membrane and goes to the citizens. The rest remains in the sea or reworks to take advantage of other elements such as salt.

In Saudi Arabia, the world's largest desalination plant with reverse osmosis technology is produced, where 50% of the water consumed by citizens is produced. In Santa Barbara of the United States of America, a reverse osmosis plant has been in place since 1992, capable of producing 30,400 m3 of drinking water per day. Smaller appliances are used on ships or even camping sites.

In Greece, reverse osmosis is a favorite option for those who live permanently on islands where the water is brackish, but also those who get water through drilling. Of course, it is the best choice for waters where water is of good quality, dangerous or microbiologically unsafe.

In recent years, we have seen an increase in sales of reverse osmosis systems to urban dwellers where traditionally water is not as bad but worsens year after year.

Domestic reverse osmosis works as follows: Water passes through three stages of water filtration to remove as many harmful elements as possible, chlorine, soil, rust, etc. We try to reach the osmosis membrane as clean as possible. This will drain less water into the drain.

After these three filtration stages have passed, the water passes through the semipermeable membrane of osmosis. Here the dirty water is drained into the drain and the clean water is stored in the tank so we can drink it.

As soon as we open the tap, the system sends water from the tank after it has passed through a flavor filter. At this stage you can add several filters such as ultraviolet radiation, alkaline filter, metal enrichment filter, etc.