HYDRAULIC MODEL OF A GAS-LIFT BIOREACTOR WITH FLOCCULATING YEAST

The hydraulic model of a gas lift bioreactor, during a continuous alco holic fermentation by using a strongly flocculating yeast, is analysed . Sucrose at two different concentrations (50 and 100 g/l) was used as substrate and the dilution rate for all the experiments was 1 h(-1). The biomass concentrations were between 85 and 110 g dry weight/l. A s timulus response technique was used to obtain the Residence Time Distr ibution curves, a pulse of a lactose solution being used as the tracer . Mixing time was determined by means of the response to a pulse of an acid tracer. These experiments were carried out by using an on-line d ata-acquisition system. The bioreactor behaviour is completely homogen eous, except for high substrate and biomass concentrations. A two para meters combined model is necessary, in this case, to fit the experimen tal data. Mixing times are very low, in the order of 10 seconds.