Liquid-Liquid Separations in Biotechnology

Separation of biochemical products from dilute aqueous solutions is often difficult and expensive. The final unit cost of production is closely related to the concentration of the starting materials. There is a large repertoire of unit processes for separation and purification, and the most suitable steps must be chosen from these options. Sedimentation, precipitation and absorption processes are most common on an industrial scale. Liquid-liquid extractions can be especially useful for the extraction of biochemicals and have been an essential aspect of antibiotic purification procedures for many years. The two classes of liquid-liquid separations, immiscible solvent and coacervate systems, offer a wide range of interesting and useful separation steps. Immiscible solvent systems are most suitable for the separation of low molecular weight biochemicals while the coacervate systems are most suitable for the separation of high molecular weight biochemicals and proteins. Both types of liquid-liquid extraction technologies can be implemented at lab, pilot and manufacturing scales.