Water Treatment System | Reverse Osmosis Systems
Reverse Osmosis (RO) is the finest level of filtration available. Reverse Osmosis is a membrane process that acts as a molecular filter to remove 95 to 99% of dissolved salts and inorganic molecules, as well as organic molecules with a molecular weight greater than 100. The Reverse Osmosis membrane also removes more than 98% of residual biological and colloidal matter from the feed water, resulting in a highly purified product stream.
Osmosis is the natural process which occurs when water spontaneously flows from a purer solution, through a semi-permeable membrane into a more concentrated solution.
A semi-permeable membrane is placed between two compartments. Salt water is placed in one compartment and fresh water in the other The semi-permeable membrane will allow water to pass through it but not salt.
In order for the system to reach equilibrium, that is for the concentration on both sides of the membrane to be the same, water will flow from the fresh water compartment into the salt water compartment. This water flow will dilute the salt water and concentrate the fresh water.This will lead to an increase in the water height on the salt water side and a decrease on the fresh water side.
The height will increase until the pressure of the column of salt water is so high that it causes the water flow to stop. The difference in the water levels on the two sides is the “Osmotic Pressure”
In Reverse Osmosis the natural osmosis forces are overcome by applying an external pressure to the concentrated solution. Thus the flow of water is reversed and pure water is removed from the feed solution, leaving a more concentrated salt solution. The process water flow in reverse osmosis desalination systems can be divided into three basic streams.
1. Feed - the filtered raw water supplied to the machine.
2. Permeate - the purified water produced by forcing the feed through the semi-permeable membranes.
3. Reject - the discarded waste water containing the concentrated salts removed from the feed water
The applications for Reverse Osmosis include desalination of seawater or brackish water for potable water, industrial water and wastewater/sewage recycling.