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What is Reverse Osmosis and Benefits of Reverse Osmosis

what is Reverse Osmosis

Introduction

One of the first and most widely utilised separation methods, reverse osmosis is primarily employed in the water treatment industry. In 1950, while the technique was still rather slow and confined to a few facilities, it became widely used for desalinating seawater. Polymers and the construction of effective membranes are two areas where great progress has been made as a result of study and technological development.

This method of water purification is now widely employed for a wide variety of applications, including but not limited to industrial, domestic, commercial, and scientific. Reverse osmosis is a fascinating scientific process, and we'll learn the fundamentals of how it works right now.

WHAT IS REVERSE OSMOSIS

The process of reverse osmosis (RO), also known as ion exchange (IE), is a filtration technique used to remove molecules and ions from a solution. When a semipermeable membrane is placed between two solutions, reverse osmosis occurs when pressure is applied to one side of the membrane at a higher level than the osmotic pressure of the solution. With this barrier, even the tiniest particles of dirt and grime are trapped and filtered out. The waste product is commonly known as RO concentrate but contains many contaminants.

Reverse Osmosis Principle

To further dissect the process, let's say that a membrane prevents the solute's big molecules from passing through to the non-pressurized side. In contrast, only the pure solvent can cross the membrane. As a result, molecules of the solute begin to concentrate on one side of the membrane, while those on the other side begin to dilute. To add more complexity, the tiers of solutions shift as well. As its name implies, reverse osmosis occurs when a solvent moves in the opposite direction of the concentration gradient through a membrane. The concentration gradually decreases from high to low.

Reverse Osmosis process

There are four steps to the reverse osmosis process. Among these are: -

  • The use of a preliminary filter to remove silt
  • A pre-filter made of carbon blocks (optional)
  • An osmosis-reverse membrane
  • One more filter, this one made of carbon blocks

Stage 1

The success of the subsequent steps depends on the initial phase being completed successfully. The subsequent steps can be built upon this foundation. Therefore, a pre-filter is used at this stage to remove sediments and dirt that are larger in size from the water.

Stage 2

Once the larger contaminants have been eliminated, stage 2 contains the carbon filter, whose use is crucial. After the first stage of purification, the carbon filter gets rid of any remaining chlorine, odors, sediments, and VOCs in the water. Even though the system may come into contact with other contaminants, such as household waste and pipe waste, the carbon filter still removes them and provides us with drinkable water.

Stage 3

Because it involves purification, this is the most crucial step in the entire Reverse Osmosis process. Water is forced through tiny membranes at high pressure in order to extract the purified liquid underneath. Total dissolved solids and other impurities are removed at this stage (TDS). This system has a tube with a cross-section, a semi-permeable membrane, and porous layers. Each one filters water by forcing it across a membrane at high pressure. The germs are continuously flushed out of the system as water molecules move through it.

Stage 4

In this phase, we perform the final filtration. After the RO process, it is common to use chemical dosing or disinfection. The final step is for the purified water to be stored in a water tank or piped into the system for consumption. The total effect of this method is a 97% reduction in microbial and chemical contaminants in the water. Calcium and magnesium, which can be harmful if left in the body, are also eliminated.

Experiment of Reverse Osmosis 

In the following, an experiment is used to demonstrate the process of reverse osmosis.

How does Reverse Osmosis work?

You just need some clean water and a highly concentrated aqueous solution to conduct a simple experiment. A semipermeable membrane should be used to separate the two solutions and keep them on opposite sides. The side of the solution that has been concentrated upon should be the side that is being pressed upon. Now, water molecules can pass through the membrane and enter the freshwater side. Simply put, this is how reverse osmosis works.

Benefits of Reverse Osmosis

The following are a few of the many advantages of reverse osmosis:

  1. This method can be used to clean water of a wide range of harmful substances, such as chemicals and biological particles (like bacteria) that have been dissolved or suspended in it.
  2. This method can be used for a variety of liquid discharges and pollutants.
  3. It is used to disinfect water and keep illnesses at bay.
  4. It is useful in the process of desalinizing ocean water.
  5. It has practical applications in the medical field.

Advantages of Reverse Osmosis

The following are some of the benefits that can be gained from using reverse osmosis:

  • The membrane's integrity prevents the passage of bacteria, viruses, and pyrogens. In this regard, RO water is very similar to distilled water.
  • The readily available units are small in stature and demand minimal floor area. Home hemodialysis is an ideal treatment option for them.
  • The membrane needs to be replaced every one to two years under normal conditions of use.
  • It is feasible to completely sterilise the RO system on a regular basis using formalin or another sterilant.

Disadvantages of Reverse Osmosis

There are a few problems with RO systems, and they are as follows.

  • Membranes made of cellulose acetate are sensitive to changes in pH. When heated above 35 degrees Celsius, their quality begins to decline. They're susceptible to infections caused by bacteria. Hydrolysis occurs over time.
  • For temperatures above 35 degrees Celsius, polyamide membranes begin to fail. There is a low threshold for free chlorine in their bodies.
  • Chlorine is harmful to thin-film composites. The feed water for high flux polysulfones must be softened or deionized for the materials to function properly.

Conclusion

Despite its flaws, RO is often regarded as the gold standard in water filtration in many nations throughout the world. However, the advantages of clean and contaminant-free water make the drawbacks of this method worthwhile.

Pooja
Pooja

Founder at gcelab.com, Pooja is an Entrepreneur unlocking human potential. Working in the Principles of Lean Start-up, Pooja believes in Transparency and User Happiness the most. Pooja’s background in teaching gives her a sophisticated grasp on even the most tedious aspect of course building. She is passionate about people who believe that good is not enough.

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