title: Anaerobic mixed-culture fermentation of aqueous ammonia-treated sugarcane bagasse in consolidated bioprocessing.
abstract: The MixAlco process is an example of consolidated bioprocessing (CBP) in which anaerobic mixed-culture fermentation biochemically converts any biodegradable feedstock into carboxylate salts. Downstream processing thermochemically transforms the resulting salts into mixed alcohol fuels or gasoline. To enhance digestibility, sugarcane bagasse was treated under mild conditions (55 degrees C, 24 h, and 30% aqueous ammonia solution with a loading of 10 mL/g dry biomass). Using NH(4)HCO(3) buffer, the feedstock (80% ammonia-treated sugarcane bagasse/20% chicken manure) was anaerobically fermented by a mixed culture of marine microorganisms at 55 degrees C. Four-stage countercurrent fermentations were performed at various volatile solids loading rates (VSLRs) and liquid residence times (LRTs). The highest acid productivity (1.14 g/(L day)) occurred at a total acid concentration of 29.8 g/L. The highest conversion (65%) occurred at a total acid concentration of 27.6 g/L. The continuum particle distribution model (CPDM) predicted the experimental total acid concentrations and conversions within 4.98% and 10.41%, respectively. When using NH(4)HCO(3) buffer, ammonia pretreatment is an attractive option. The CPDM "map" shows that both high volatile solid conversions (78.8%) and high acid concentrations (32.6 g/L) are possible with 300 g/(L liquid) substrate concentration, 30 days LRT, 2 g/(L day) solid loading rate and NH(4)HCO(3) buffer.
authors.affiliation: Department of Microbiology and Cell Science, Florida Center for Renewable Chemicals and Fuels, University of Florida, PO Box 110700, Gainesville, Florida 32611-0700, USA. zhihongfu@hotmail.com
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Fu
authors.forename: Mark T
authors.initials: MT
authors.lastname: Holtzapple
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D001421:Bacteria, Anaerobic / Q000502:physiology*; D019149:Bioreactors / Q000382:microbiology*; D002482:Cellulose / Q000737:chemistry / Q000378:metabolism*; D031786:Saccharum / Q000737:chemistry* / Q000382:microbiology*; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D000641:Ammonia; D002482:Cellulose; C027433:bagasse