Ultrafiltration (UF) involves pressure-driven separation of particulate matter from a liquid solution. The technology is used to remove particulate and microbial contaminants, but it does not remove ions and small molecules. In many power plants Ultrafiltration plants are used for removal of colloidal silica from boiler feed water. Pressure generated by a centrifugal pump ensures separation of solids from the liquid. UF plants are automated and have low operational labor requirements. UF plants do require cleaning of membranes. UF membranes reject solutes ranging in size from 0.03 microns and larger.