Membrane technology covers all engineering approaches for the transport of substances between two fractions with the help of permeable membranes. In general, mechanical separation processes for separating gaseous or liquid streams use membrane technology. Membrane separation consists of different process operating on a variety of physical principles and applicable to a wide range of separations of miscible components • These methods yield only a more concentrated liquid stream than feed. Membrane separation processes have several advantages. These include : 1) Low energy alternative to evaporation in concentrating a dilute feed, particularly when the desired material is thermally labile or when the desired component is a clear liquid 2) The chemical and mechanical stresses on the product are minimal and since no phase change is involve the energy requirement is modest 3) Product concentration and purification can be achieved in a single step and the selectivity towards the desired product is good 4) The method can easily be scaled up In bioprocess industry, membrane separation is widely used because of the mild operating conditions