Sucrose conversion by immobilized invertase in a multiple air-lift loop bioreactor.

A new bioreactor series within one vessel, the multiple air-lift loop reactor (MAL), is introduced. In the MAL, a series of air-lift loop reactors is incorporated into one vessel. From residence time distribution studies, it was shown that the three-compartment MAL behaves as a series of three ideal mixers. A continuously operated MAL, containing immobilized invertase as a model biocatalyst, was evaluated. The advantage of approaching plug flow by using a bioreactor cascade could be shown by comparing substrate conversion in the three-compartment MAL to that in a single vessel at the same overall dilution rate. This was done for two sets of experimental conditions, which were chosen by using a previously developed model. Intrinsic kinetic parameters of the immobilized enzyme, needed for the model calculations, were determined experimentally. Model calculations gave good approximations of the results. The model incorporates external mass-transfer resistance and diffusion and reaction in the biocatalyst beads.