ASSESSMENT OF CELLULOSIC HYDROLYSATE FERMENTATION INTEGRATED TO FIRST GENERATION ETHANOL PRODUCTION

The ethanol fermentation in batch mode with cell recycle using cellulosic hydrolysate (C6 liquor) from sugarcane bagasse, blended with substrate from sugarcane juice and molasses (1G) was assessed in bioreactor of 2 L (New Brunswick, USA). The applied steps of second generation (2G) were hydrothermal pretreatment of sugarcane bagasse at 190°C, 12 min, solid-liquid separation, cellulignin washing with water and enzymatic saccharification using commercial enzyme complex (10 FPU/ g cellulignin). The hydrolysis was carried  at 50°C, 48 h and pH 4.8. The current sugarcane juice treatment with phosphating, liming, and flocculation is used too on C6 liquor to reduce impurities matter from hydrolysis. The material was sterilized at 121°C, 15 min. The 1G substrate was prepared with 21% of TSAI (total sugars as inverted) from molasses and remaining from sugarcane juice, following treatment and sterilization. After, these two carbon sources were blended according to maximum theoretical C6 available to integration, which in this process, corresponds to 12% of C6 from cellulosic hydrolysate. The fermentations were performed at 33°C using industrial strain of Saccharomyces cerevisiae. After each fermentation, the cells were recovered and treated before to start new fermentation.The initial values were S₀: 150 g/ L, X₀: 20 g/ L and P₀: 5 g/ L. A mathematical model was proposed as a complementary approach to evaluate the fermentation of 1G2G. All fermentations showed similar profiles of substrate, ethanol and cells, resulting in an average specific ethanol productivity of 11 g/ L. h, average yield of 85% and cellular viability of 87%.