Ultrafiltration is dependent on size of the particle. The driving force for transport across the membrane is a pressure differential. UF processes operate at 2-10 bars. Typical rejected species include Proteins and other biomolecules, polymers and colloidal particles. Ultrafiltration processes perform feed clarification, concentration of rejected solutes and fractionation of solutes. Ultrafiltration is typically not effective at separating organic streams. Ultrafiltration membranes are capable of retaining species in the range of 10,000-500,000 daltons of molecular weight, with pore sizes ranging from 10-1000 Angstroms (103-0.1 microns). These are mostly described by their nominal molecular weight cutoff (10,000-100,000 MWCO). UF is available in Organic and Ceramic Material of construction.