title: Anaerobic thermophilic fermentation for carboxylic acid production from in-storage air-lime-treated sugarcane bagasse.
abstract: Wet storage and in situ lime pretreatment (50 °C, 1-atm air, 56 days, excess lime loading of 0.3 g Ca(OH)(2)/g dry biomass) of sugarcane bagasse (4,000 g dry weight) was performed in a bench-scale pile pretreatment system. Under thermophilic conditions (55 °C, NH(4)HCO(3) buffer, methane inhibitors), air-lime-treated bagasse (80 wt.%) and chicken manure (20 wt.%) were anaerobically co-digested in 1-L rotary fermentors by a mixed culture of marine microorganisms (Galveston, TX). During four-stage countercurrent fermentation, the resulting carboxylic acids consisted of primarily acetate (average 87.7 wt.%) and butyrate (average 9.0 wt.%). The experimental fermentation trains had the highest yield (0.47 g total acids/g volatile solids (VS) fed) and highest selectivity (0.79 g total acids/g VS digested) at a total acid concentration of 28.3 g/L, which is equivalent to an ethanol yield of 105.2 gal/(tonne VS fed). Both high total acid concentrations (>44.7 g/L) and high substrate conversions (>77.5%) are predicted for countercurrent fermentations of bagasse at commercial scale, allowing for an efficient conversion of air-lime-treated biomass to liquid transportation fuels and chemicals via the carboxylate platform.
authors.affiliation: Florida Center for Renewable Chemicals and Fuels, Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 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: D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism*; D001709:Biotechnology / Q000379:methods*; D017610:Calcium Compounds / Q000737:chemistry; D002264:Carboxylic Acids / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D005285:Fermentation; D006358:Hot Temperature; D010087:Oxides / Q000737:chemistry; D031786:Saccharum / Q000378:metabolism / Q000382:microbiology*; D012623:Seawater / Q000382:microbiology
chemical_list: D017610:Calcium Compounds; D002264:Carboxylic Acids; D010087:Oxides; D002482:Cellulose; C027433:bagasse; C016538:lime