ABSTRACT
Bioethanol is potentially a green alternative to gasoline for the transportation industry. With the interest in lignocellulosic biomass as feedstock for bioethanol production, an increase is expected in the energy requirements for the purification step by distillation. Among alternative purification technologies, pervaporation possesses advantages due to simplicity of operation, low energy requirements, an absence of chemicals and consequently, a low operational cost. Moreover, a pervaporation unit coupled with a fermenter enables working in continuous mode, enhanced productivity of yeast, enhanced ethanol yield, reduced liquid effluent and minimized water consumption. In our study, during fermentation coupled with pervaporation, a feed flow rate of 15 L/h was found to be most suitable. At an initial sugar concentration of 13% (w/v), the time taken for 100% conversion reduced to 6 h, compared to 8 h in the case of conventional fermentation without PVMBR. The specific productivity increased by 60%, and the yield enhanced by 7%. Total flux and the ethanol flux through the pervaporation unit were 257.4 g/m2.h and 36.9 g/m2.h, respectively. Separation factor and enrichment factor of the PDMS membrane were found to be 2.7 and 2.5, respectively. This study suggests that an integrated process of fermentation and pervaporation can be employed in a continuous operational mode as energy efficient technology with higher productivity and yield in the biorefinery industry.
