Fermentation of sugarcane bagasse and chicken manure to calcium carboxylates under thermophilic conditions.
Sugarcane bagasse and chicken manure were anaerobically fermented to carboxylic acids using a mixed culture of marine microorganisms at 55 degrees C. Using the MixAlco process--an example of consolidated bioprocessing--the resulting carboxylate salts can be converted to mixed alcohol fuels or gasoline. To enhance digestibility, sugarcane bagasse was lime pretreated with 0.1 g Ca(OH)(2)/g dry biomass at 100 degrees C for 2 h. Four-stage countercurrent fermentation of 80% sugarcane bagasse/20% chicken manure was performed at various volatile solids (VS) loading rates and liquid residence times. Calcium carbonate was used as a buffer during fermentation. The highest acid productivity of 0.79 g/(L day) occurred at a total acid concentration of 21.5 g/L. The highest conversion (0.59 g VS digested/g VS fed) and yield (0.18 g total acids/g VS fed) occurred at a total acid concentration of 15.5 g/L. The continuum particle distribution model (CPDM) predicted the experimental total acid concentrations and conversions at an average error of 10.14% and 12.68%, respectively. CPDM optimizations show that high conversion (>80%) and total acid concentration of 21.3 g/L are possible with 300 g substrate/(L liquid), 30 days liquid residence time, and 3 g/(L day) solid loading rate. Thermophilic fermentation has a higher acetate content (approximately 63 wt%) than mesophilic fermentation (approximately 39 wt%).
Fu
Zhihong
Z
Department of Microbiology and Cell Science, Florida Center for Renewable Chemicals and Fuels, University of Florida, PO Box 110700, Gainesville, FL 32611-0700, USA. zhihongfu@ufl.edu
Holtzapple
Mark T
MT
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002264:Carboxylic Acids / Q000032:analysis* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D002645:Chickens; D005285:Fermentation; D008372:Manure; D031786:Saccharum / Q000201:enzymology*; D013696:Temperature
D002264:Carboxylic Acids; D008372:Manure; D002482:Cellulose; C027433:bagasse; D002118:Calcium