Downstream processing and analytical bioseparation both refer to the separation or purification of biological products, but at different scales of operation and for different purposes. Downstream processing implies manufactures of a purified product fit for a specific use, generally in marketable quantities, while analytical biosepation refers to purification for the sole purpose of measuring a component or components of a mixture, and may deal with sample sizes as a small as a single cell. Development of novel mechanical systems for selective separation of solid and liquid mixtures must become a top priority for current research investment to reduse the reliance on expensive chromatographic and themal separation methods. Downstream processing may also incude farmulation activities. signifying the transition from drug substance to drug substance to drug product. Furthermore, downstream processing considerations include resource management and management of multiple waste streams and biohazards. the succes of biotechnology for bulk product manufacturing will heavily depend on engineering solutions in the down stream processes in which separation and purification have a crucial role with respect to commercial development. Downstream prcesssing in biotechnology concerns the separation and purification of the bioproduct down stream of the fermenter as the name implies and this is the focus of this book.