Enhanced Bioethanol Production in Batch Fermentation by Pervaporation Using a PDMS Membrane Bioreactor

The integration of batch fermentation and membrane-based pervaporation process in a membrane bioreactor (MBR) was studied to enhance bioethanol production compared to conventional batchfermentation operated at optimum condition. For this purpose, a laboratory-scale MBR system wasdesigned and fabricated. Dense hydrophobic polydimethylsiloxane (PDMS) membrane was used for pervaporation. For fermentation, pure stock culture of Saccharomyces cerevisiae as microorganism andglucose as substrate were used. In conventional batch fermentation, the yields of cell and ethanolconcentration based on substrate consumption were 0.32 and 0.54 g/g, respectively. But in MBR, these values improved to o.41 and 0.59 g/g, respectively. In addition, the ethanol productivity increased by at least 26.83% over conventional bioreactor. Furthermore, ethanol concentration in permeated side wasapproximately 6 to 7 times higher than that of the broth. Based on Monod biological kinetic model,maximum specific growth rate was 0.966 h-1, more than 0.864 h-1 in conventional system. Compared to conventional batch fermentation, the MBR resulted in increase of cell density, decreasing ethanol inhibition, improved productivity and yield, and resumption of clean and concentrated ethanol. These effects can be attributed to the presence of membrane as a selective separation barrier for removal of ethanol from fermentation broth

Keywords:

Batch Fermentation , Ethanol Inhibition , Membrane Bioreactor , Pervaporation , Polydimethylsiloxane