A numerical investigation of the hydrodynamic and mass transfer behavior of a liquid-liquid semi-partition bioreactor (SPB) designed for in-situ extractive fermentation

Organisms used in fermentation processes are sometimes inhibited by accumulation of products or by-products. One route to circumvent this is via extractive fermentation. To facilitate this, novel bioreactor designs are required, such as the semi-partition bioreactor (SPB) which has been designed for in-situ extractive fermentation. This study reports on the numerical investigation of an SPB, considering phase separation, hydrodynamics and mass transfer behaviour. Key findings illustrate that a minimum agitation speed is necessary to attain system homogeneity in the mixer section. Furthermore, the results indicate that the working principle of the bioreactor will be effective for liquid-liquid partitioning and mass transfer followed by flux exchange between the mixer and settler sections and subsequent phase separation in the settler section. This mechanism has a shorter characteristic time than the replenishment of the bioreactor with recycled (and back-extracted) extractant. The reactor thus shows promise as a route for fermentations susceptible to product inhibition.