ABSTRACT
Filtration is defined as the process of separation of two or more substances. This is
achieved by a variety of interactions between the substance or objects to be removed and
the filter. In addition the substance that is to pass through the filter must be a fluid, that is,
a liquid or gas. The simplest method of filtration is to pass a solution of a solid and fluid
through a porous interface so that the solid is trapped or retained, while the fluid passes
through. This principle relies upon the size difference between the particles making up
the fluid, and the particles making up the solid. Filtration is widely used within the
biopharmaceutical industry to remove these contaminants. Microorganism removal is
either required to achieve a sterile filtrate or if the pharmaceutical product is thermally
sterilized to reduce the bioburden and therefore avoid elevated levels of endotoxins which
is an indirect indicator of the presence of cell-debris from Gram negative organisms
(ASTM F838-05).
