Tuesday, April 20, 2010
11-65

Ethanol fermentation in a tower reactor with flocculant yeast

Thályta Fraga Pacheco, Hávala Barbosa Reis, Miriam Maria de Resende, Vicelma Luiz Cardoso, and Eloízio Júlio Ribeiro. Faculty of Chemical Engineering, Uberlândia Federal University, P.O. Box 593, Uberlândia, 38400-902, Brazil

In this work was to studied the alcoholic fermentation with a strain of flocculant yeast in a batch tower recirculation reactor with ascending flow, two technological innovations for ethanol industry.  The use of a tubular reactor of ascending flow guarantees larger production efficiency with smaller fermentation time. The fermentation technology with flocculants yeasts could dispense the centrifugation step to separate the yeast of fermented wine for reuse. A central composite design (CCD) was employed to evaluate the influence of initial substrate and inoculum concentration and flow recirculation in the reactor on the responses yield, ethanol productivity and the residual sucrose concentration. In the culture medium the initial inoculum concentration varied from 4,7 to 45,3%, the range of initial sucrose concentration was varied from 100 to 220 g/L, and the recirculation flow of 2,6 at 17,1 cm³/s. All fermentations assays were conduced during seven hours. The optimized experimental conditions were: initial sucrose concentration 180 g/L, recirculation flow 13 cm³/s and high cellular inocullum concentrations. In this point the responses presented an yield of practically 100%, a productivity around 14 getanol/L.h and a residual sucrose concentration of approximately 7,5 g/L after seven hour of fermentation time. Therefore, it was obtained a productivity 50% larger than the usually found in the industry, with excellent yield and residual level of sucrose smaller than the industrial. This technology still requests studies to guarantee your applicability, because unknown particularities existents in the flocculation process, but it presents a great potential and technical viability.