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Consolidated bioprocessing of sugarcane bagasse and chicken manure to ammonium carboxylates by a mixed culture of marine microorganisms

Fu, Zhihong, Holtzapple, Mark T.
Bioresource technology 2010 v.101 no.8 pp. 2825-2836
biomass, renewable energy sources, biorefining, sugarcane bagasse, lignocellulose, cellulose, poultry manure, ammonium bicarbonate, carboxylic acids, calcium carbonate, buffers, batch fermentation
The MixAlco process, an example of consolidated bioprocessing (CBP), was utilized for anaerobic fermentation of 80% lime-treated sugarcane bagasse/20% chicken manure at 55°C by a mixed culture of marine microorganisms. NH₄HCO₃ was recommended by this study to replace CaCO₃ buffer to neutralize the produced carboxylic acids. The resulting ammonium carboxylates can be converted to gasoline or mixed alcohol fuels by downstream processing. Four-stage countercurrent fermentations at various volatile solids loading rates (VSLR) and liquid residence times (LRT) showed the highest acid productivity (1.27g/(L·day)) and highest conversion (76%) occurred at a total acid concentration of 24.4 and 31.3g/L, respectively. The Continuum Particle Distribution Model (CPDM) predicted the experimental total acid concentrations and conversions within 9.05% and 14.39%, respectively. The CPDM “map” indicates that both high acid concentrations (>50g/L) and high conversions (>72%) are possible with 300g substrate/(L liquid) concentration, 30 days liquid residence time, 5.4g/(L·day) solid loading rate, and NH₄HCO₃ buffer. The present study suggests that mixed culture biotechnology in the MixAlco process provides an alternative “carboxylate platform” for biomass conversion.