title: Effects of enzyme loading, densification, and storage on AFEX-pretreated biomass for ethanol production.
abstract: Corn stover, switchgrass, and prairie cordgrass were treated with an ammonia fiber expansion (AFEX) process and a novel densification method (ComPAKco). Separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) were used to evaluate impacts of densification. ComPAKco densification is characterized by low-temperature and low-energy requirements, resulting in compacted biomass briquettes (CBB) 1-2 cm square, with a bulk density of 380-460 kg/m(3). Feedstocks were evaluated before and following AFEX pretreatment, after densification, and after storage. Two enzyme doses were tested. The low rate used 5 filter paper units (FPU) of Spezyme CP (cellulase) and 21.3 cellobiase units (CBU) of Novozyme 188 (aka NS50010 [β-glucosidase]) per gram of glucan. The high dosage rate was three times higher and resulted in 40-56 % and 33-82 % higher ethanol yields with SHF and SSF, respectively. Trials revealed no adverse effect on ethanol yield following densification or 6-month storage of densified, AFEX-pretreated feedstocks.
authors.affiliation: Department of Biology and Microbiology, South Dakota State University, Alfred Dairy Science Hall 213, P.O. Box 2104A, Brookings, SD, 57007, USA.
authors.forename: Gwen
authors.initials: G
authors.lastname: Biersbach
authors.affiliation: Department of Agricultural and Biosystems Engineering, North Dakota State University, 1221 Albrecht Blvd., Fargo, ND, 58102, USA.
authors.forename: Binod
authors.initials: B
authors.lastname: Rijal
authors.affiliation: Department of Agricultural and Biosystems Engineering, North Dakota State University, 1221 Albrecht Blvd., Fargo, ND, 58102, USA.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Pryor
authors.affiliation: Department of Biology and Microbiology, South Dakota State University, Alfred Dairy Science Hall 213, P.O. Box 2104A, Brookings, SD, 57007, USA. william.gibbons@sdstate.edu.
authors.forename: William R
authors.initials: WR
authors.lastname: Gibbons
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D044602:Cellulases / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D011312:Pressure; D013696:Temperature
chemical_list: D000431:Ethanol; D000641:Ammonia; D044602:Cellulases
keywords: AFEX; Biomass densification; Corn stover; Ethanol; Prairie cordgrass; Switchgrass