Reverse Osmosis Filtration
Ro water purification is basically when water from a saline solution is separated from the dissolved salts or solids. The water saline solution is separated by the reverse osmosis membrane. The membrane filters out all the dissolved chemicals and solids by using the feed water to pressurized the product water through the membrane. As the clean water passes through the membrane, the remaining feed water inside the tanks becomes more concentrated and brackish. In order for the feed water to continue pumping, some of the water needs to be discharged out so that it doesn’t continue creating brackish water inside of the tank. Not only that but by removing the brackish water this will also cost less energy and money.
Ro water purification has five main stages or components and these includes:
Pretreatment/pre-filter: The water is pretreated by removing suspended solids and other chemicals that would interfere when passing through the membrane. Some of the things it screens out are dirt, sand, and chlorine. This is also known as water softening.
Pressurization/Activated Carbon – The pump increases the pressure on the pretreated water to be compatible with the semi-preamble membrane. There is also a carbon pre-filter in this stage. It is a carbon block cartridge with a .5 or 10 micron filtration. This means it usually is able to remove chlorine, taste, odor, and any other chemicals inside the water. But it’s main job is to remove chlorine and oils away from the membrane so that the membrane does not become plugged or damaged. There are usually multiple carbon pre-filters in a single reverse osmosis system. The reason being is that this will enable the membrane to have better sanitation and sustain a longer life.
Membrane separation: The membrane then helps move along the water and blocks all the other dissolved salts and minerals from coming through. The brine with all the dissolved salts and chemical is discharged out while the clean water is carried along to a storage tank. The membrane is the most important element in a Ro system because it is the membrane that actually filters and purifies the water.
Storage tank/storage bladder: The tank for the purified water to be stored after it is discharged from the semipermeable membrane. The storage tanks all vary from different sizes depending on how much water a household uses or needs.
Post-treatment stabilization: Before the clean, purified water can be ready to be used, it needs some adjustments.. These adjustments includes ph changes and the removal of dissolved gases. It also rids of contaminants that causes odor and bad taste due to the plastic tank or tubing of the reverse osmosis storage bladder. This is usually accomplished by the carbon post-filter cartridge. This stage filters out any chlorine or contaminants that were missed by the other cartridges. This filtering is also to prevent corrosion as well.
In many ro water purifier, the filtration actually has as many as six or seven stages. These stages are mainly added carbon filters or water softening steps that can better enhance the membrane. Click to see RO stages.
Reverse Osmosis Systems – RO systems