In process engineering, purification or downstream processing refers to all processes that are used to separate and purify fermentation products from a fermentation broth in a biotechnological process. This term includes mechanical , thermal , electrical and physico-chemical processes.
Product purification comprises a number of processing steps that are intended to increase and guarantee the purity of the end products. Depending on the product, more or fewer processing steps are necessary. One of the first steps of the separation of the microorganism (cell separation) from the product material, which is obtained outside of the organisms, or after completion of cell lysis to be carried out separation of products from the cell interior. This is followed by the isolation (capture) of the product from the fermentation broth and finally the product is enriched in several purification steps (polishing). The final step is the formulation of the end product in the desired purity. In the biotechnological process, cleaning represents the highest proportion of the process costs; these are normally 40 to 60% of the total costs, but can make up over 80% of the costs for products that are very laborious to clean, such as recombinant proteins or monoclonal antibodies for medical use .
The number of purification steps depends on the desired purity of the end product and the initial concentration in the fermentation broth. With an increasing number of cleaning steps, the increase in purity per cleaning step decreases, and there is also a loss of product in all cleaning steps, which means that the product yield decreases with the number of cleaning steps.
- Mechanical separation ( e.g. centrifugation , sedimentation , filtration , flotation )
- Thermal processes (e.g. crystallization , evaporation , rectification , distillation , chromatography , dialysis (chemistry) )
- Electrical processes ( e.g. magnetic separation , electrolysis )
- Physico-chemical processes ( e.g. reactive precipitation , polymerisation , depolymerisation , derivatisation )
- Wilhelm RA Vauck, Hermann A. Müller: Basic operations of chemical process engineering . 11. revised u. exp. Edition, Wiley-Vch, Weinheim 2001, ISBN 3-342-00687-0
- O.-W. Reif, Thomas Scheper: Purification. In: Garabed Antranikian: Applied Microbiology. Springer-Verlag Berlin, Heidelberg 2006, ISBN 978-3-540-24083-9 , pp. 427-443