The ultrafiltration process falls between reverse osmosis and microfiltration in terms of the size of particles removed, with ultrafiltration removing particles in the 0.002-to-0.1-micron range and typically removing organics over 1,000 molecular weight while allowing ions and smaller organic materials to pass through.
How does it work?
Untreated water is forced against a semipermeable membrane. The membrane allows the water molecules to pass through and screens out the colloids, much like a sieve. Excess water is used to wash the colloids off the surface and to a drain. Unlike in most filtration, the sieve does not fill up with trapped material because the colloids are too large to fit into the opening of the sieve. A good analogy would be dumping a mixture of water and marbles (the colloids) over a window screen (the membrane). Most of the water would pass through the screen. The remaining water would help wash the marbles off the screen and would be sent to waste with the marbles. The screen would not become plugged because the marbles are too large to fit into the openings.
What can this be used for?
Ultrafiltration systems are commonly used by Trucent to remove contaminants from washer baths and for various waste treatment applications.