DYNAMICS OF CHEMICAL-ELEMENTS IN THE FERMENTATION PROCESS OF ETHANOL-PRODUCTION

Brazil has become the largest producer of biomass ethanol derived from sugar cane. The industrial production is based on the fermentation of sugar cane juice by yeast, inside of large volume vats, in a fed-batc h process that recycles yeast cells. To study the dynamics of chemical elements in each operating cycle, five stages of the fermentation pro cess were considered: must, yeast suspension, wine, non-yeast wine and yeast cream. For this, a mass balance of the terrigenous elements, Ce , Co, Cs, Eu, Fe, Hf, La, Na, Sc, Sm, and Th, and the sugar cane plant elements, Br, K, Rb, and Zn, were established in fermentation vats of an industrial scale unit, with sampling undertaken during different c limatic conditions (dry and rainy periods). A similar distribution of the sugar cane characteristics elements was found for the stages analy sed, while for the terrigenous elements a trend of accumulation in the yeast cream was observed. Preferential absorption of Br, K, Rb, and Z n by yeast cells was indicated by the smaller concentrations observed in yeast suspension than in yeast cream.