title: Efficient production of ethanol from waste paper and the biochemical methane potential of stillage eluted from ethanol fermentation.
abstract: Waste paper can serve as a feedstock for ethanol production due to being rich in cellulose and not requiring energy-intensive thermophysical pretreatment. In this study, an efficient process was developed to convert waste paper to ethanol. To accelerate enzymatic saccharification, pH of waste paper slurry was adjusted to 4.5-5.0 with H2SO4. Presaccharification and simultaneous saccharification and fermentation (PSSF) with enzyme loading of 40 FPU/g waste paper achieved an ethanol yield of 91.8% and productivity of 0.53g/(Lh) with an ethanol concentration of 32g/L. Fed-batch PSSF was used to decrease enzyme loading to 13 FPU/g waste paper by feeding two separate batches of waste paper slurry. Feeding with 20% w/w waste paper slurry increased ethanol concentration to 41.8g/L while ethanol yield decreased to 83.8%. To improve the ethanol yield, presaccharification was done prior to feeding and resulted in a higher ethanol concentration of 45.3g/L, a yield of 90.8%, and productivity of 0.54g/(Lh). Ethanol fermentation recovered 33.2% of the energy in waste paper as ethanol. The biochemical methane potential of the stillage eluted from ethanol fermentation was 270.5mL/g VTS and 73.0% of the energy in the stillage was recovered as methane. Integrating ethanol fermentation with methane fermentation, recovered a total of 80.4% of the energy in waste paper as ethanol and methane.
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Nishimura
authors.affiliation: College of Architecture and Environment, Sichuan University, No. 24 South Section 1, First Ring Road, Chengdu 610065, China. Electronic address: tanli212002@foxmail.com.
authors.forename: Li
authors.initials: L
authors.lastname: Tan
authors.affiliation: College of Architecture and Environment, Sichuan University, No. 24 South Section 1, First Ring Road, Chengdu 610065, China.
authors.forename: Zhao-Yong
authors.initials: ZY
authors.lastname: Sun
authors.affiliation: College of Architecture and Environment, Sichuan University, No. 24 South Section 1, First Ring Road, Chengdu 610065, China.
authors.forename: Yue-Qin
authors.initials: YQ
authors.lastname: Tang
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan; College of Architecture and Environment, Sichuan University, No. 24 South Section 1, First Ring Road, Chengdu 610065, China.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kida
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Morimura
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry; D056804:Biofuels; D002480:Cellulase / Q000737:chemistry; D002482:Cellulose / Q000378:metabolism; D003247:Conservation of Natural Resources; D000431:Ethanol / Q000737:chemistry*; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007218:Industrial Microbiology; D008697:Methane / Q000737:chemistry*; D010209:Paper; D059027:Recycling / Q000379:methods*; D012037:Refuse Disposal / Q000379:methods*; D012441:Saccharomyces cerevisiae; D013696:Temperature; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D056804:Biofuels; D000431:Ethanol; D002482:Cellulose; D001617:beta-Glucosidase; D002480:Cellulase; D008697:Methane
keywords: Ethanol; Methane fermentation; Presaccharification; Simultaneous saccharification and fermentation (SSF)