Ultrafiltration (UF)
Ultrafiltration (UF) is similar to RO and NF, but is defined as a crossflow process that does not reject ions. UF rejects solutes above 1000 daltons (molecular weight). Because of the larger pore size in the membrane, UF requires a much lower differential operating pressure: 10 to 100 psig (0.7 to 6.9 bar).
The Ultrafiltration process is a separation process using membrane filtration, where membrane modules of the filters are available in plate-and-frame, spiral-wound, and tubular configurations with pore sizes in the range of 0.1 to 0.001 micron.
How It Works:
Ultrafiltration uses hollow fibers of membrane material and the feed water flows either inside the shell, or in the lumen of the fibers. Suspended solids and solutes of high molecular weight are retained, while water and low molecular weight solutes pass through the membrane. Ultrafiltration is not fundamentally different from reverse osmosis, microfiltration or nanofiltration, except in terms of the size of the molecules it retains. When strategically combined with other purification technologies in a complete water system, UF is ideal for the removal of colloids, proteins, bacteria, pyrogens, proteins, and macromolecules larger than the membrane pore size from water.