PROSES PRODUKSI ETANOL OLEH Saccharomyces Cerivisiae DENGAN OPERASI KONTINYU PADA KONDISI VAKUM

Abstract

Fermentation is one of method for ethanol production. The problem occurring in fermentation process is ethanol inhibition. The influences of ethanol inhibition are membrane stucture destruction of the yeast cell and protein denaturation that makes the microbes growth inhibited and decrease its productivity. To solve the problem, fermentation performed in vacuum condition. In vacuum condition, etanol boiling point will decrease, therefore some ethanol as fermentation product will be vaporized The aims of this research are to study the effects of pressure to ethanol and yeast cell productivities. The substrate used in this research was molasses with 50-150 gram/L of sugar concentrations. The operation pressure were 0.098 and 0.49 atm. The experiment started with molasses pretreatment, Saccaromyces Cereviseae cultivation and starter production. Fermentation was carried out in 3 L fermentor contains of mixed substrat and starter (10% v/v) using continuous operation with substrate flow rate of 62.5 ml/. The highest productivity of ethanol was 0.767 gram/L/h obtained at substrate concentration 125 gram/L with pressure 0.098 atm. This research shows that the increase of sugar concentration could improve productivity of ethanol and biomass. In vacuum condition, ethanol productivity was more constant and the yeast growth was improved.