Natural Osmosis Essay

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[RO-System]

Reverse Osmosis, known as RO system, is a technology that is used to remove a large majority of contaminant from water by pushing the water under pressure through a semi-permeable membrane.
To understand the purpose and the process of Reverse Osmosis, should understand the natural Osmosis operation.
Natural Osmosis:
The phenomenon of osmosis occurs when pure water flows from a dilute saline solution through a membrane into a higher concentrated saline solution. (Example of osmosis is our kidneys absorb water from our blood).
Figure (A): Natural osmosis operation principle. (Zahid amjad)
A semi-permeable membrane is placed between two sides. “Semi-permeable” means that the membrane is permeable to some species, and not permeable
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Ultimate height difference between columns is “osmotic pressure” and this operation called “Natural Osmosis”.
The figure above, shows that natural osmosis can cause a rise in the height of the salt solution. This height will increase until the pressure of the column of water (salt solution) is so high that the force of this water column stops the water flow. The equilibrium point of this water column height in terms of water pressure against 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 is the basic of the term “reverse osmosis”.
Reverse Osmosis is the process of Natural Osmosis in reverse, by which Osmosis naturally occurs without any requirement of energy, but to reverse the process of natural osmosis energy is required. Pressure is used to push the water through the membrane and that pressure should be greater than the nature osmotic pressure in order to desalinate (deionize) water in the process to allow the pure water through holding back majority of
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The movement of a pure solvent to equalize solute concentrations on each side of a membrane generates osmotic pressure. If applied pressure greater than osmotic pressure to higher salt concentration side the pure water will flow in opposite direction to low salt concentration side. Therefore producing pure water from salt solution since semi-permeable membrane does not allow salt to pass through it. This is called “Reverse Osmosis“.
If the applied pressure is equal to osmotic pressure, no flow will occur.
The rate of water transport depends on (membrane properties including thickness, solution temperature, and difference in pressure applied). Efficiency of reverse osmosis system depends on water pressure coming into the system and the temperature of that water. Every change occur, membrane performance will changed as well as higher pressures increase the production.
In very simple terms, feed water is pumped into a Reverse Osmosis (RO) system and end up with two types of water coming out of the RO system: clean water has the majority of contaminants removed and is called permeate of product water. The bad water is the water that contains all of the contaminants that were unable to pass through the system membrane and known as the

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