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Acetone–butanol–ethanol production using pH control strategy and immobilized cells in an integrated fermentation–pervaporation process

Wu, Hao, He, Ai-yong, Kong, Xiang-ping, Jiang, Min, Chen, Xiao-peng, Zhu, Da-wei, Liu, Gong-ping, Jin, Wan-qin
Process Biochemistry 2015 v.50 pp. 614-622
Clostridium acetobutylicum, butanol, fermenters, fouling, immobilized cells, pH, pervaporation, solvents, sugarcane bagasse
The effects of pH and cell immobilization on acetone–butanol–ethanol (ABE) production coupled with a pervaporation membrane have been investigated using Clostridium acetobutylicum XY16. The solvent productivity of 0.29g/L/h was obtained using a two-stage controlled-pH in the coupled process, which was 11% higher than a previous process without pH control, nevertheless, membrane was still fouled. Furthermore, butanol in the fermenter remained below the critical concentration using a larger membrane, solvent productivity achieved 0.38g/L/h. However, these methods could not prevent membrane fouling, the average permeation flux and butanol separation factor decreased by 41.6% and 31.3%. Then, sugarcane bagasse was used as a cell immobilization carrier and applied to the coupled process; many cells aggregated and adsorbed on sugarcane bagasse surface, the dry cell weight (DCW) in broth was maintained at 1.1g/L. Membrane fouling was relieved, the pervaporation maintained a steady state for more than 90h, the average permeation flux was 0.676kg/m2/h, which only decreased by 13.9% compared to that in the initial stage, and the butanol separation factor remained stable. A maximum solvent productivity of 0.62g/L/h was also obtained. Thus, the pH control and cell immobilization are efficient methods for high-intensity ABE production with in situ recovery.