Biotechnology and Bioengineering · 1997 · 37 citations · 0 references
Life SciencesBiotechnologyChemical EngineeringBiochemical EngineeringBioprocess EngineeringFermentation EngineeringAcetic Acid FermentationAlcoholic FermentationFermentation KineticsIndustrial FermentationMicrobial FermentationOrganic Acid ProductionAcetic Acid ProductionContinuous FlowContinuous Flow OperationEthanol FermentationEthanol ProductionOrganic Loading RatePh Effects On Fermentation KineticsPropionic Acid Production
It has been found, in this study, that a new ethanol-type fermentation can be obtained in a continuous flow, high-rate acidogenic reactor receiving molasses as the feed. The operating pH must be maintained at about 4.5 to avoid onset of propionic fermentation. The acidogenic reactor had a VSS level of 20 g/L and its organic loading was as high as 80 to 90 kg COD/m3 d. The operating ORP was around -250 mV. The ethanol-type fermentation was characterized by a simultaneous production of acetic acid and ethanol, while the yield of propionic was minimal even at a high organic loading rate of 80 to 90 kg COD/m3 d, and also, the hydrogen partial pressure was as high as 50 kPa. Thus, this study has shown that the production of propionic acid is not always related to high hydrogen partial pressure. When the operating pH was increased to 5.5, the yield of propionic acid became significant. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 428–433, 1997.