Improving the economical efficiency of a simulated-moving-bed process for biofuel production from agarose in red algae

Abstract

A four-zone simulated-moving-bed (SMB) process has recently been applied to the recovery of galactose (biofuel-convertible monosugar) from agarose-hydrolysis output, which is part of agarose-based biofuel production process. To substantially improve the economical efficiency of the aforementioned biofuel production process, a new SMB process based on a three-zone advanced mode using fewer columns, pumps, and port-switching valves was proposed in this study. Its configuration and operation strategy were devised in a way to facilitate the complete regeneration of SMB solid phase against highly adsorbed impurities in the agarose-hydrolysis output while enhancing the separation margin between a key-impurity band front and a galactose product port in a feed-loaded separation zone. To investigate the advantages of such proposed SMB over the previous SMB, the two processes were optimized under equal conditions. It was found that the proposed process could significantly outperform the previous process in terms of processing rate, solvent usage, and galactose product yield while being in an advantageous position in the aspects of the equipment and maintenance costs and the potential for further acquisition of an industrially useful side-product. Furthermore, such advantage of the proposed process became greater as the required level of purity or processing rate increased.