Dfds

What is Reverse Osmosis?
Home /Reverse Osmosis / What is Reverse Osmosis?
Reverse Osmosis is a technology that is used to remove a large majority of contaminants from water by pushing the water under pressure through a semi-permeable membrane.
This article is aimed towards an audience that has little or no experience with Reverse Osmosis and will attempt to explain the basics in simple termsthat should leave the reader with a better overall understanding of Reverse Osmosis technology and its applications.
This article covers the following topics:
1. Understanding Osmosis and Reverse Osmosis
2. How does Reverse Osmosis (RO) work?
3. What contaminants does Reverse Osmosis (RO) remove?
4. Performance and design calculations for Reverse Osmosis (RO) systems
1.Salt Rejection %
2. Salt Passage %
3. Recovery %
4. Concentration Factor
5. Flux Rate
6. Mass Balance
1. Understanding the difference between passes and stages in a Reverse Osmosis (RO) system
1. 1 stage vs 2 stage Reverse Osmosis (RO) system
2. Array
3. Reverse Osmosis (RO) system with a concentrate recycle
4. Single Pass vs DoublePass Reverse Osmosis (RO) systems
1. Pre-treatment for Reverse Osmosis (RO)
1. Fouling
2. Scaling
3. Chemical Attack
4. Mechanical Damage
1. Pre-treatment Solutions for Reverse Osmosis (RO)
1. Multi Media Filtration
2. Microfiltration
3. Antiscalants and scale inhibitors
4. Softening by ion exchange
5. Sodium Bisulfite (SBS)injection
6. Granular Activated Carbon (GAC)
1. Reverse Osmosis (RO) performance trending and data normalization
2. Reverse Osmosis (RO) membrane cleaning
3. Summary
↑
Understanding Reverse Osmosis
Reverse Osmosis, commonly referred to as RO, is a process where you demineralize or deionize water by pushing it under pressure through a semi-permeable Reverse Osmosis Membrane.↑
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 soiland 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 asemi-permeable membrane, then the water with the lower salt concentration would begin to migrate towards the water container with the higher salt concentration.
A semi-permeable membrane is a membrane that will allow some atoms or molecules to pass but not others. A simple example is a screen door. It allows air molecules to pass through but not pests or anything larger than the holes in the screen door.Another example is Gore-tex clothing fabric that contains an extremely thin plastic film into which billions of small pores have been cut. The pores are big enough to let water vapor through, but small enough to prevent liquid water from passing.
Reverse Osmosis is the process of Osmosis in reverse. Whereas Osmosis occurs naturally without energy required, to reverse the process of osmosis youneed to apply energy to the more saline solution. A reverse osmosis membrane is a semi-permeable membrane that allows the passage of water molecules but not the majority of dissolved salts, organics, bacteria and pyrogens. However, you need to 'push' the water through the reverse osmosis membrane by applying pressure that is greater than the naturally occurring osmotic pressure in order to...