Membrane filters act as a barrier to separate contaminants from water, or they remove the particles contaminating the water. Reverse osmosis, ultrafiltration, and nanofiltration all use a membrane in their different filtration processes.
What is membrane filtration?
Filter membranes have different configurations. There are reverse osmosis (RO) membranes, ultrafiltration (UF) membranes, and nanofiltration (NF) membranes. They all approach the membrane filtration process a little bit differently.
How does a membrane filter work?
Reverse osmosis applies pressure to a semipermeable membrane that allows the water molecules to pass through while flushing the dissolved inorganic compounds to the drain. So it separates the water into two pathways.
Ultrafiltration doesn't separate the water like a reverse osmosis membrane. It actually is just an ultra-fine particulate or sediment filter. With mechanical filtration particulate down to 0.025 microns cannot pass through the ultrafiltration membrane.
Nanofiltration membrane technology works very similar to reverse osmosis, except the filtration is not quite as fine.
What's the difference between a reverse osmosis and an ultrafiltration membrane?
Reverse osmosis and ultrafiltration differ quite a bit. Reverse osmosis is able to reject dissolved minerals from the water, whereas UF only filters solids or particulate. Reverse osmosis is able to get out dissolved inorganic minerals that will pass through the UF membrane.