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  Nasratun Masngut

Postgraduate Student

Intensification of Biobutanol Production


Biobutanol is a high value biofuel and potentially a better fuel extender than ethanol. The market demand is expected to increase dramatically, if biobutanol can be produced economically via the ABE (acetone, butation, ethanol) fermentation. ABE fermentation performed by Clostridium species can be divided into two distinct phases, acidogenic and solventogenic phases. Acetic acid and butyric acid were produced during the acidogenic phase, and after that acetone, butanol and ethanol were produced during solventogenic phase. In general, the biphasic metabolism of Clostridium species is directly associated with cell growth status. Exponentially growing cells mainly produce acids, while solvent is usually produced when cells enter the late exponential phase. If solvent production could be initiated in early exponential phase, the solvent productivity might be increased as the fermentation time would be shortened. In industry, established fermentation technologies are using several parallel static vessels in staggered sequence to provide a steady flow of fermentation broth and to overcome inhibition. This requires a huge floor space to accommodate multiple process equipment which leads to increase in capital cost. In addition, several intrinsic problems (such as low solvent yield, expensive raw material and costly recovery process) also contribute to the incompetence of this fermentation compared to the chemical route.


One way to develop an economic production route of this ABE fermentation is through intensification of the fermentation process to improve solvent yield and productivity. In this work, a novel intensified bioreactor called the oscillatory baffled bioreactor (OBB) was evaluate for this process (Figure 1).


Fig. 1 - A 2 L Batch oscillatory baffled bioreactor


This novel bioreactor works by oscillating the fluid in a baffled column, thereby producing uniform efficient mixing throughout the bioreactor via eddy generation due to the interaction between the orifice-type baffles and the periodically reversing flow. The resultant radial and axial velocities are of the same magnitude; resulting in uniform mixing in each inter-baffle region, along the length of the column. One particular advantage of the OBB is for performing ‘long’ reactions (such as fermentations) in a more compact design than conventional tubular plug flow reactors. A further advantage for the ABE fermentation could be that the OBB provides relatively low shear, uniform mixing, thereby achieving homogenous conditions, with less cell damage than comparable stirred tank reactors.



For more information please contact Prof Adam Harvey.




 Last modified: 02-Jun-2017