Process Simulation of Continuous Bioconversions in Aqueous Two-Phase Systems

Progress in biotechnology largely depends on fermentation optimisation and improvement in downstream processing. These improvements get strongly supported if an integration of fermentation and product extraction can be verified in one processing unit. Continuous bioconversions in aqueous two-phase systems show a great potential of combining these two unit operations. General requirements are the capability of cells and substrates to enrich in one of the phases and the tendency of products to diffuse in the opposite phase. This integrated process is most promising for reaction systems, which exhibit kinetics characterised by product inhibition and, in addition, the process facilitates cell recycling and supports an increase in cell concentration. However, the industrial realisation of this technique is still not fully developed mainly due to difficulties in measurement and control, and to a lack of profitable products. In this work the conversion of glucose to ethanol is used as a model study to develop mathematical optimisation criteria and to create a “feasibility window” for the ongoing search for products.