Conversion of paper sludge to ethanol by separate hydrolysis and fermentation (SHF) using Saccharomyces cerevisiae

• Published in: Biomass & bioenergy Vol. 35; no. 4; pp. 1600 - 1606
• Main Authors: Peng, Lincai, Chen, Yuancai
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2011; Elsevier
• Subjects: Alcohols: methanol, ethanol, etc; Alternative fuels. Production and utilization; Applied sciences; Cellulase; Combinatorial analysis; endo-1,4-beta-glucanase; Energy; enzymatic hydrolysis; Ethanol; Ethyl alcohol; Exact sciences and technology; experimental design; Fermentation; Fuels; Hydrolysis; mathematical models; Optimization; Paper sludge; pulp and paper sludge; Response surface methodology; Saccharification; Saccharomyces cerevisiae; Sludge; sugars; Hydrolysis; Paper sludge; Response surface methodology; Fermentation; Cellulase; Saccharomyces cerevisiae
• ISSN: 0961-9534; 1873-2909
• DOI: 10.1016/j.biombioe.2011.01.059

The conversion of ethanol from paper sludge using the separate hydrolysis and fermentation (SHF) process with cellulase and Saccharomyces cerevisiae GIM-2 were investigated in this paper. Optimization strategy based on statistical experimental designs was employed to enhance degree of saccharification by enzymatic hydrolysis of paper sludge. Based on the Plackett–Burman design, hydrolysis time, substrate concentration and cellulase dosage were selected as the most significant variable on the degree of saccharification. Subsequently, the optimum combination of the selected factors was investigated by a Box-Behnken approach. A mathematical model was developed to show the effects of each factor and their combinatorial interactions on the degree of saccharification. The optimal conditions were hydrolysis time 82.7 h, substrate concentration 40.8 g L−1 and cellulase dosage 18.1 FPU g−1 substrate, and a degree of saccharification of 82.1% can be achieved. When hydrolysate was further fermented with S. cerevisiae GIM-2, the conversion rate of sugar to ethanol was 34.2% and the ethanol yield was 190 g kg−1 of dry paper sludge, corresponding to an overall conversion yield of 56.3% of the available carbohydrates on the initial substrate. The results derived from this study indicate that the response surface methodology is a useful tool for optimizing the hydrolysis conditions to converse paper sludge to ethanol. : ► Bio-ethanol production from paper sludge is feasible without complex pre-treatment. ► Cellulase dosage and time had obvious effects on the degree of saccharification. ► The optimal degree of saccharification of 82.1% can be achieved using the RSM. ► The highest ethanol yield reached to 190 g kg−1 of dry paper sludge by the SHF.