Separate hydrolysis and fermentation (SHF) of pretreated sugar beet pulp (SBP) into ethanol

Environmentally friendly technologies are becoming more popular because of the increase in environmental pollution. One of them is the ethanol production process using renewable resources. One of these renewable resources is Sugar Beet Pulp (SBP) as a renewable, available and inexpensive raw material with high sugar content for ethanol fermentation. The process of converting biomass to ethanol consists mainly of three stages: pretreatment, enzymatic hydrolysis and fermentation. In this study, ethanol production from SBP was achieved through three steps: acid treatment, enzymatic hydrolysis of cellulose content in treated SBP into fermentable sugar and fermentation of fermentable sugar to ethanol. The weight of dried SBP after acid treatment was 34% of the original dried SBP. Two cellulase commercial enzymes named SternEnzymeC21032 and Cellic C Tec2 were used for hydrolysis of cellulose content in 10 and 15% solid load of the treated SBP. The Saccharomyces cerevisiae strains CY3079 and AH15 were used for the fermentation of the reduced sugar. The highest ethanol yields by S. cerevisiae CY3079 and AH15 were 5.61 and 5.58% of reduced sugar in hydrolyzed SBP with a 15% solid load. According to the results reported in this study, each ton of dried SBP gives 100 kg of ethanol. However, this level is relatively low, and more experiments are still needed to increase the productivity of this bioprocess.