Monday, April 30, 2007 - 3:40 PM
3-09

Continuous production of ethanol from starch using glucoamylase and yeast co-immobilized in pectin gel

Raquel de Lima Camargo Giordano, Chemical Engineering Department, Universidade Federal de São Carlos, Washington Luiz, Km 235, Monjolinho, São Carlos, SP, Brazil, Joubert Trovati, PPGEQ, Universidade Federal de São Carlos - UFSCar, Washington Luiz, Km 235, Monjolinho, São Carlos, Brazil, and Willibaldo Schmidell Netto, Chemical Engineering Department, Universidade Federal de Santa Catarina - UFSC, Trindade, Florianópolis, Brazil.

This work presents a continuous process to produce ethanol from starch using glucoamylase and Saccharomyces cerevisiae co-immobilized in pectin gel. Enzyme was immobilized on macroporous silica, after silanization and activation of the support with glutaraldehyde. The silica-enzyme derivative was co-immobilized with yeast in pectin gel. This bio-catalyst was used to produce ethanol from liquified manioc root flour syrup, in three fixed bed reactors. An adequate reactor yeast load was previously determined: 0,05g wet yeast/mL of reactor (0,1g wet yeast/g gel ), and kept constant in all the experiments. The enzyme concentration in the reactor was defined by running batch experiments, using different amount of silica-enzyme derivative coimmobilized with yeast in pectin gel to produce ethanol from starch. The chosen reactor enzyme concentration, 3,77U/mL, allowed the fermentation to be the limiting step in the batch experiment, keeping the glucose concentration vey low.  In this condition, using initial substrate concentration of 332,0 g/L of total reducing sugars, 1g gel/1mLmedium, it was achieved ethanol productivity of 8,3 g/L/h, for total conversion of the substrate and 92.7% of yield. In the continuous runs, using the same batch operational conditions, it was achieved ethanol productivity of 5,8g ethanol/L/h, with 94% of substrate conversion and 83% of ethanol yield. External diffusion effects in the process seemed to be prevented when operating at superficial velocities above 3.7 x10 –4 cm/s.

See more of Session 3b
See more of General Submissions

See more of The 29th Symposium on Biotechnology for Fuels and Chemicals (April 29 - May 2, 2007)