Liquid mixing and mass transfer in a modified bubble column with suspended particles

Immobilized enzyme and immobilized whole cell as biocatalysts were commonly applied in bioprocess engineering. The biocatalysts which were suspended in a reactor had a substantial effect on the reactor performance. This work provided a modified bubble column with double net draft tubes to improve the performance of liquid mixing and mass transfer in the column with suspended particles. Mixing time and volumetric mass transfer coefficient were employed as indications for liquid mixing and mass transfer, respectively. A novel method for determining the mixing time was developed by using the pulse test with hot water. Two thermocouples were employed. The suspended particles were calcium alginate beads with 7% (w/w) and 8.7% (w/w) in the column. The mixing time of the proposed column could be 26% lower than that of the conventional bubble column. The mass transfer coefficient could be up to 50% higher than that of the bubble column.