Ultrafiltration: It is a variety of membrane filtration in which forces like pressure or concentration gradients lead to a separation through a semipermeable membrane. Suspended solids and solutes of high molecular weight are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in the permeate (filtrate). This separation process is used in industry and research for purifying and concentrating macromolecular (10³ – 10⁶ Da) solutions, especially protein solutions. Ultrafiltration is not fundamentally different from microfiltration. Both of these separate based on size exclusion or particle capture. It is fundamentally different from membrane gas separation, which separate based on different amounts of absorption and different rates of diffusion. Ultrafiltration membranes are defined by the molecular weight cut-off (MWCO) of the membrane used. Ultrafiltration is applied in cross-flow or dead-end mode.

Applications:

• Industries such as chemical and pharmaceutical manufacturing, food, beverage processing, and waste water treatment, employ ultrafiltration in order to recycle flow or add value to later products.
• Blood dialysis.
• Drinking water
• Protein concentration
• Filtration of effluent from paper pulp mill
• Cheese manufacture
• Removal of pathogens from milk
• Process and waste water treatment
• Enzyme recovery
• Fruit juice concentration and clarification
• Dialysis and other blood treatments
• Desalting and solvent-exchange of proteins (via diafiltrating)
• Laboratory grade manufacturing