Scale-up and application of a cyclone reactor for fermentation processes

A cyclone reactor for microbial fermentation processes was developed with high oxygen transfer capabilities. Three geometrically similar cyclone reactors with 0.5 l, 2.5 l and 15 l liquid volume, respectively, were characterized with respect to oxygen mass transfer, mixing time and residence time distribution. Semi-empirically correlations for prediction of oxygen mass transfer and mixing times were identified for scale-up of cyclone reactors. A volumetric oxygen mass transfer coefficient k(L)a of 1.0 s^-1 (available oxygen transfer rate with air: 29 kg m^-3 h^-1) was achieved with the cyclone reactor at a volumetric power input of 40 kW m^-3 and an aeration gas flow rate of 0.2 s^-1. Continuous methanol controlled production of formate dehydrogenase (FDH) with Candida boidinii in a 15 1 cyclone reactor resulted in more than 100% improvement in dry cell mass concentration (64.5 g l^-1) and in about 100% improvement in FDH space-time yield (300 U l^-1 h^-1) compared to steady state results of a continuous stirred tank reactor.