ULTRAFILTRATION uses a membrane very similar in design to reverse osmosis systems except that the ultrafilter’s pores are slightly larger. The ultrafilter is used to remove pyrogens and other long chain organic molecules such as RNase from the purified water.

Since a high percentage of the water brought to the ultrafilter passes through it, it will eventually plug if not maintained. In a properly designed system, the ultrafilter is regularly and tangentially washed free of contaminants. With this type of design, ultrafiltration is an outstanding technology for ensuring very consistent ultrapure water quality.

Crossflow filtrat ion in an ultrafilter showing pyrogens and particles larger than 0.002 micron being retained, while only pure water molecules pass through the pores.