title: Improving ethanol production from alfalfa stems via ambient-temperature acid pretreatment and washing.
abstract: The concept of co-production of liquid fuel (ethanol) along with animal feed on farm was proposed, and the strategy of using ambient-temperature acid pretreatment, ensiling and washing to improve ethanol production from alfalfa stems was investigated. Alfalfa stems were separated and pretreated with sulfuric acid at ambient-temperature after harvest, and following ensiling, after which the ensiled stems were subjected to simultaneous saccharification and fermentation (SSF) for ethanol production. Ethanol yield was improved by ambient-temperature sulfuric acid pretreatment before ensiling, and by washing before SSF. It was theorized that the acid pretreatment at ambient temperature partially degraded hemicellulose, and altered cell wall structure, resulted in improved cellulose accessibility, whereas washing removed soluble ash in substrates which could inhibit the SSF. The pH of stored alfalfa stems can be used to predict the ethanol yield, with a correlation coefficient of +0.83 for washed alfalfa stems.
authors.affiliation: Department of Biological System Engineering, University of Wisconsin, Agricultural Engineering Building, Madison, WI 53706, USA. Electronic address: szhou34@wisc.edu.
authors.forename: Shengfei
authors.initials: S
authors.lastname: Zhou
authors.affiliation: USDA-ARS, U.S. Dairy Forage Research Center, Madison, WI 53706, USA. Electronic address: Paul.Weimer@ars.usda.gov.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Weimer
authors.affiliation: USDA-ARS, U.S. Dairy Forage Research Center, Madison, WI 53706, USA. Electronic address: Ronald.Hatfield@ars.usda.gov.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Hatfield
authors.affiliation: Department of Biological System Engineering, University of Wisconsin, Agricultural Engineering Building, Madison, WI 53706, USA. Electronic address: trunge@wbi.wisc.edu.
authors.forename: Troy M
authors.initials: TM
authors.lastname: Runge
authors.affiliation: KUHN North America, 1501 West Seventh Avenue, Brodhead, WI 53520, USA. Electronic address: matthew.digman@kuhn.com.
authors.forename: Matthew
authors.initials: M
authors.lastname: Digman
mesh_terms: D000383:Agriculture / Q000379:methods; D000431:Ethanol / Q000138:chemical synthesis*; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D000455:Medicago sativa / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry; D012820:Silage; D013464:Sulfuric Acids / Q000737:chemistry; D013696:Temperature
chemical_list: D011134:Polysaccharides; D013464:Sulfuric Acids; D000431:Ethanol; C033158:sulfuric acid
keywords: Ambient-temperature sulfuric acid pretreatment; Ash; Ensiling; Ethanol production; Washing