There are a lot of processes used to obtain pure water from contaminated water sources such as distillation, ion exchange, electrodialysis, reverse osmosis etc. This article will examine the technology of reverse osmosis.
Reverse Osmosis(RO) can used for :
- desalination of sea water and brackish water
- purifying water contaminated with heavy metals, pesticides
- recycling waste water and reclaiming useful material from waste stream
A semi permeable membran (RO membrane) is place between two compartments. The phenomenon of osmosis occurs when pure water flows a dilute solution in one compartment through the RO membrane into a hinger concentrated saline solutionin the other causing a rise in the height of the salt solution in the compartmen of the higher concentrated solution.
The water flow will stop when the pressure of the column of the salt solution equal to the difference in chemical potential between the two aqueous solution. The equilibrium point of the water column height in term of water pressure againts the membrane is called osmotic pressure
If a force is applied to this column of water , the direction of water flow through the membrane can be reversed. This phenomenon is called reverse osmosis. This reversed flow produce pure water from the salt solution, since the membrane is not permeable to salt.
- Asymmetric Membrane - Cellulose Acetate (CA) membrane
- Thin Film Composite Membrane- Polyamide (PA) membrane
.... to be continued...insya Allah
