Ultrafiltration

Ultrafiltration is a low-pressure membrane process used to separate high molecular weight compounds from a feed stream. Ultrafiltration has larger pores than nanofiltration and reverse osmosis and is therefore the least costly of the three to operate. As Separation by ultrafiltration [1] a result ultrafiltration requires fewer membrane elements and lower pressures for operation. Ultrafiltration is useful for the separation of delicate materials since it is a non-denaturing method of separation.

Ultrafiltration is widely used in industry. It is used when fine filtration or removal of organic contaminants is needed. Examples of particles in the size for separation by ultrafiltration are: paint pigments, ink, asbestos, tobacco smoke, gelatin, colloidal silica, tannins, and lignins. In general salts and low Ultrafiltration Unit [3] molecular weight species can pass through the membrane while suspended solids become concentrated on the other side of the membrane. Uses in industry where this form of separation is most useful are: pretreatment for other forms of purification such as ion exchange, gelatin and protein concentration in the pharmaceutical industry, sugar clarification in the food and beverage industry, cheese and whey concentration, oily waste concentration in waste water, and electronic deposition for paint applications. Cross flow membrane filtration is commonly used for the concentration and purification of proteins and other biological particles from suspensions. Other uses include production of ultra pure water, egg and animal blood processing, clarification of juice, downstream processing, membrane bioreactors, treatment of bleach plant effluents, and recovery of lignin compounds in the pulp and paper industry. Ultrafiltration can be used to reject virus, bacteria, pyrogens, endotoxins, and particulates but not ionic species.