Contactors for Aqueous Two-Phase Extraction: A Review

Improved bioseparation techniques are increasingly important for biotechnology because downstream processing accounts for a major share of the production cost. Several processes do not become commercially feasible for this reason involved in the purification protocols (50-90% of the final product cost). Downstream processing poses several problems mainly because of two reasons (1). Target biomolecule or compound is generally present in dilute form and (2). It is present along with several other undesired compounds, needing a chain of purification steps to obtain the desired product in the required purity as well as concentration. Hence there is a need for efficient and economically feasible downstream processing methods. Aqueous Two Phase Extraction is one such method which offers several advantages such as biocompatibility (due to presence of high water content), ease of scale-up and scope for continuous operation. In ATPE, equipment used in the conventional organic extraction in the chemical industry (e.g., spray, packed column, etc.) can be adapted easily when multistage procedure is needed and the phase separation is achieved in these contactors by gravity separation, thereby eliminating the need of expensive equipments. In spite of having so many advantages, ATPE method did not realize the wide commercial adoption that it richly deserves, due to several factors. In the present review, special emphasis is given to different equipments employed for ATPE both at large and lab scales, besides attempting analysis of equipment design parameters of these equipments along with operational conditions that affect their performance. This review also attempts to present major advantages and challenges faced for the industrial adoption of the technique.