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2019 Published Online.
《Waste and Biomass Valorization》
页码:1-11

Fermentative Production of Ethanol from Acid Hydrolyzate of Rice Water Waste Using Saccharomyces cerevisiae: Experimental and Kinetic Studies

Masoud Hatami-manesh,Habibollah Younesi,Nader Bahramifar,Maedeh Mohammadi,Hossein Khakpour

Department of Environmental Science, Faculty of Natural Resources, Tarbiat Modares University, Noor, Mazandaran 64414-356, Iran

Abstract: Rice water waste, a starch-bearing effluent waste stream, was utilized as an abundant and low-cost substrate for ethanol production. Prior to the fermentation process, rice water waste was hydrolyzed using dilute H2SO4 solution. To attain the highest concentration of sugars with a minimum amount of inhibitory by-products during the acid hydrolysis, different acid concentrations (2-6 v/v %), hydrolysis temperatures (60-100 ℃) and reaction times (0-200 min) were examined. The maximum catalytic efficiency (ηE =27.36) was obtained using 4% H2SO4 at 80 ℃ for 100 min; wherein, the concentration of reducing sugars, furfural and 5- hydroxymethylfurfural (HMF) in the hydrolyzate was 43.32, 0.29 and 0.17 g L-1, respectively. This hydrolyzate was utilized as a substrate for ethanol fermentation using Saccharomyces cerevisiae; the maximum ethanol concentration, yield, and cell density were 18.65 g L-1, 0.41 g ethanol g-1 sugar and 3.68 g L-1, respectively. The kinetics of the acid hydrolysis process was studied using “two-fraction” model. The kinetic constants indicated that the rate of release of reducing sugars from starch was high; while, the degradation rate of reducing sugar to furfural and HMF was negligible. Moreover, multi-response nonlinear regression analysis was performed on the experimental data to determine the kinetic parameters regarding cell growth, substrate utilization, and ethanol production.

Keywords: Ethanol;Rice water waste;Kinetics;Acid hydrolysis;Furfural

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