The Effect of Operating Parameters and Matrix Properties on the Productivity of an Expanded Bed Adsorption Column

Expanded bed adsorption (EBA) combines clarification, concentration and purification into a single processing step reducing processing time and increasing productivity. Much work has been conducted on model proteins but little attention has been paid to the emerging issues of tailoring the operational variables of matrix size, operating flowrate and ligand type so as to maximise process outputs. The aims of this study were to investigate the effects of matrix properties and operating parameters on breakthrough behaviour and productivity. Second generation matrices designed to operate at high flowrates were also examined. Operating at low velocities, beds formed from smaller particles had a shallower breakthrough than beds formed from large particles but the latter were more productive. At the higher velocities typically utilised in EBA, the behaviour of beds formed from either small or large particles was comparable in terms of breakthrough with the beds made up of small particles being slightly more productive than those containing large particles. A prototype 2nd generation EBA matrix consisting of a multi-modal ligand that could operate at high conductivity levels typical of fermentation broths was also examined. It was found that the productivity could be increased 5-fold as compared with commercially available matrices, with no loss of yield or purity. Conventional breakthrough curve analysis is not applicable in situations of variable particle size and operating velocity. Results using a novel dimensionless group to facilitate comparison between unlike systems is presented.