Search

The production of acetone, butanol, and ethanol (ABE) by fermentation is a process that had been used by industries for decades. Two stage immobilized column reactor system integrated with liquid-liquid extraction was used with immobilized Clostridium acetobutylicum DSM 792, to enhance the ABE productivity and yield. The sugar mixture (glucose, mannose, galactose, arabinose, and xylose) representative to the lignocellulose hydrolysates was used as a substrate for continuous ABE production. Maximum total ABE solvent concentration of 20.30 g L(-1) was achieved at a dilution rate (D) of 0.2h(-1), with the sugar mixture as a substrate. The maximum solvent productivity (10.85 g L(-1)h(-1)) and the solvent yield (0.38 g g(-1)) were obtained at a dilution rate of 1.0 h(-1). The maximum sugar mixture utilization rate was achieved with the present set up which is difficult to reach in a single stage chemostat. The system was operated for 48 days without any technical problems., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The objective of this study was to optimize continuous acetone-butanol-ethanol (ABE) fermentation using a two stage chemostat system integrated with liquid-liquid extraction of solvents produced in the first stage. This minimized end product inhibition by butanol and subsequently enhanced glucose utilization and solvent production in continuous cultures of Clostridium acetobutylicum B 5313. During continuous two-stage ABE fermentation, sugarcane bagasse was used as the cell holding material for the both stages and liquid-liquid extraction was performed using an oleyl alcohol and decanol mixture. An overall solvent production of 25.32g/L (acetone 5.93g/L, butanol 16.90g/L and ethanol 2.48g/L) was observed as compared to 15.98g/L in the single stage chemostat with highest solvent productivity and solvent yield of 2.5g/Lh and of 0.35g/g, respectively. Maximum glucose utilization (83.21%) at a dilution rate of 0.051/h was observed as compared to 54.38% in the single stage chemostat., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Highlights: [•] Study suggests the preference of biomass feedstocks appropriate for ABE-fermentation. [•] Effect of varying lignocellulosic sugar concentrations in continuous column reactor. [•] Multi linear regression (MLR) modeling successfully used for continuous production of solvents. [•] Scale up of column reactor is successfully demonstrated. [Copyright &y& Elsevier]

Abstract: SO2–ethanol–water (SEW) spent liquor from spruce chips was successfully used for batch and continuous production of acetone, butanol and ethanol (ABE). Initially, batch experiments were performed using spent liquor to check the suitability for production of ABE. Maximum concentration of total ABE was found to be 8.79g/l using 4-fold diluted SEW liquor supplemented with 35g/l of glucose. The effect of dilution rate on solvent production, productivity and yield was studied in column reactor consisting of immobilized Clostridium acetobutylicum DSM 792 on wood pulp. Total solvent concentration of 12g/l was obtained at a dilution rate of 0.21h−1. The maximum solvent productivity (4.86g/lh) with yield of 0.27g/g was obtained at dilution rate of 0.64h−1. Further, to increase the solvent yield, the unutilized sugars were subjected to batch fermentation. [Copyright &y& Elsevier]