In the pharmaceutical industry, ultrafiltration (UF) membranes are used extensively in the downstream purification of recombinant proteins or monoclonal antibodies. However, the fouling of membranes after a unit operation?especially when recombinant proteins or monoclonal antibodies are highly concentrated?is a common problem. Typically, normalized water permeability (NWP) of a membrane can be reduced to about 20 percent of its original permeability at the end of an ultrafiltration-diafiltration (UF-DF) operation.
