초록
<P><B>Abstract</B></P> <P>The objective of the present investigation is to develop and evaluate economic production of biofuels (ethanol) using immobilized yeast cells (<I>Saccharomyces cerevisiae</I> NCIM 3095) from renewable carbon source <I>Madhuca indica</I> (Mahua flowers). The entrapment of yeast cells in calcium alginate-polyvinyl alcohol (CA-PVA) film were found most suitable immobilizing matrix as a protective carrier to increase the stability and tolerance limit during continuous fermentation. Under similar fermentation conditions, immobilized yeast cells produced higher ethanol yield (∼0.48 g/g) and productivity (∼28 g/L/h) as compared to traditional suspended free cells system in continuous fermentation with dilution rate of 0.4/h. Further, the fermenter was coupled with solar driven membrane distillation (SDMD) process for separation and concentration of ethanol after fermentation. The new system does not require centrifugation/microfiltration for separation and/or recycle of biomass as the cells were immobilized and could be easily separated by simple filtration. The SDMD with cross flow module in rectangular shape and counter-current flow of streams (hot and cold) ensured higher ethanol flux (23 kg EtOH/m<SUP>2</SUP>/24 h) in comparison to existing literature. The new process design is compact yet flexible, eco-friendly, energy intensive and sustainable process for the development of economic biofuel production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Immobilized yeast cells in CA-PVA gel ensured higher yield and productivity vis-à-vis existing literature. </LI> <LI> Ethanol produced from Mahua flowers in a fermenter integrated with SDMD. </LI> <LI> DCMD using PTFE/PP membrane yielded high ethanol flux. </LI> <LI> The novel system represents eco-friendly and energy efficient process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>