llecture(5&6)

An Introduction to Bio separations
Bio separation is the name given to the practice of purifying biological products on large-scale, using fundamental aspects of engineering and scientific principles. The end goal of bio separation is to refine molecules, cells and parts of cells into purified fractions.
Bio separation study the processes used to recover, isolate, predicate and polish products made by/of biological materials
Biological products can be separated and purified depending upon the following characteristics: density, diffusivity, electrostatic charge, polarity, shape, size, solubility and volatility.
Bio separation or downstream processing: - refers to the recovery, isolation, purification and polishing of products synthesized by biotechnological processes (e.g. r-DNA technology, conventional microbial fermentation, enzyme technology, and hybridism technology).
Differences between Bio separation and Chemical Separation
Although bio separation is based on traditional chemical separation processes, they do differ in significant ways. This is because the materials being purified and separated in bio separation are biological substances rather than the synthetic chemicals used in traditional techniques. As such, substances such as proteins, carbohydrates and nucleic acids are not suitable for the rigors of traditional techniques like packed-bed adsorption and evaporation.
Often, the desired final product is only found in very minute quantities in the starting substance from which they are refined. Because of this, vast quantities of dilute product streams must undergo processing in order to obtain a small amount of pure product. Meanwhile, there are often unwanted impurities in the starting substance, which have similar genetic makeup to the desired product, thus making separation very difficult.
Because biological products are more apt to degradation than chemical ones, this rules out the use of many common organic solvents in bio separation, since they have a tendency to act as a catalyst for degradation. Furthermore, many biological substances are unstable when heated and as such have to be handled in sub-ambient temperatures.