| Summary: | 碩士 === 東海大學 === 化學工程與材料工程學系 === 99 === The ABE (acetone, butanol, ethanol) fermentation is characterized by its low productivity. In this paper, this issue is overcome with an innovative separation process that employs the adsorption and pervaporation technology. A control ABE fermentation experiment was characterized by incomplete glucose utilization due to butanol toxicity to Clostridium acetobutylicum, while fermentation coupled with in situ recovery by pervaporation and adsorption resulted in complete utilization of glucose, greater productivity, improved cell growth, and concentrated recovered ABE stream.
In adsorption process, use of activated carbon appears to be the more attractive as it can be used to concentrate butanol from model solutions and results in complete desorption of butanol. The butanol adsorption capacity of activated charcoal is 42 mg/g in model solution. Direct use of adsorbents without removing cells from the fermentation broth may foul the adsorbents. In order to overcome this problem, either a microfiltration or an ultrafiltration membrane can be placed between the adsorption column and bioreactor or cells can be centrifuged and returned to the reactor.Problems such as interactions between adsorbents and nutrients, sugars, biomass, toxicity of adsorbents, and the ease of desorption still remain to be addressed.
Acetone butanol ethanol (ABE) were produced in an integrated fermentation-product recovery system using Clostridium acetobutylicum, a PEBA(polyether-block-amide) membrane and a 5-Lfermentor containing initial substrate (glucose) concentration of 80 g/L. Cells of C. acetobutylicum were removed from the cell culture using a ceramic filtration and returned to the 5-L fermentor. The ABE was removed from the filtration permeate using a PEBA pervaporation membrane.
A PEBA pervapoaration membrane was synthesized to recover acetone, butanol, and ethanol from model solutions and the Clostridium acetobutylicum (ABE) fermentation broth. At the effects of beginning concentration of butanol to the performance of ABE fermentation incorporating with pervaporation. At 7±1 g/L butanol concentration to operate pervaporation have the higher butanol productivity and yield is 0.277 g /l/ h and 0.207 g/g. A continuous operation with pervaporation and feeding 150 g/L glucose at the rate of 15 ml/hr for 24 h. It have the butanol productivity and yield is 0.270 g /l/ h and 0.169 g/g for 84 hours.
In situ removal of ABE by pervaporation has been reported to be one of the most important techniques of solvent removal. During these studies we were able to maintain the ABE concentration in the fermentation broth below toxic levels.
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