REDUCTION OF STILLAGE's VOLUME IN THE PRODUCTION OF ETHANOL BY RECIRCULATION.
Sustainable process-product development & green chemistry
Sustainable & Clean Technologies-II: Energy Production (T1-5P)
Keywords: stillage, recirculation, L/L extraction, ethanol production, clean technology
The production of energy from biomass has been object of wide research in the last years, especially the production of fuel alcohol, in Colombia, has increased thanks to laws promulgated by the government; parallel to this the generation of residues increases also, in this case called stillage or vinasse, for a conventional process 13 to 15 liters are obtained of stillage by liter of ethanol, which for the quantity of ethanol projected, of 750 million liters/ year of alcohol, would be generated between 9750 and 11250 million liters of stillage/year, a so big quantity.
As alternative to reduce the volume of stillage, has been proposed the recirculation of the same ones to the fermentation, like dilution water, nevertheless the inhibitor presence in the effluent, like acetic acid, limits its application. The present work evaluated the effect of the acetic acid concentration on the alcoholic yield in the fermentation, a negative effect was observed for concentrations higher than 2.5 g/L, for 7.5 g/L the ethanol productivity diminished 66% and biomass 50%; the use of extractants agents of acid also studied to improve the recirculation possibilities, palm oil methyl ester was defined like the best extractant of those proven, in addition to its almost null toxicity on the yeast and low cost.
Five successive recycles were carried out, the percentage of stillage recirculated was 70% of the water of dilution of the molasses, parallely were developed the processes with and without extraction, for the first case the ethanol productivity was not affected, whereas for the second a diminution of 30% was observed.
In addition to acetic acid, the solid concentration also inhibits the biomass from 15% w/w and it affects the ethanol productivity in values near 26% w/w.
During the five fermentations a water saving was obtained of 56% and one reduction of the volume of stillage of 44%.
See the full pdf manuscript of the abstract.
Presented Monday 17, 13:30 to 15:00, in session Sustainable & Clean technologies - II: Energy Production (T1-5P).
