Process simulation of an integrated green protein biorefinery using nanofiltration membrane and ethanol fermentation.

• Integration of a green biorefinery with ethanol fermentation was evaluated. • 90% of the green juice crude protein was recovered in the protein concentrate. • Nanofiltration raised the sugar composition in the brown juice from 2.4 to 13.6 %. • Purification of ethanol from concentrated brown juice used up to 45% less energy. • DWC was the best choice to purify ethanol among the tested extractive distillations. The objective of this study is to propose the integration of a green protein biorefinery with ethanol production and to highlight the potential of nanofiltration membrane technologies and extractive distillation in the separation and purification of valuable substances. Depending on the product and its purity, the nanofiltration membrane can help in decreasing energy expenditure and greenhouse gas emissions while extractive distillation overcomes the water–ethanol azeotrope formation. The aim is to enhance the sustainability of biorefinery processes by integrating new separation techniques and adopting process intensification. The concentration of the residual brown juice using nanofiltration reduced its water content and favored the sugar conversion into ethanol while concomitantly decreasing the formation of byproducts. It has been shown that these configurations (with the presence of nanofiltration and intensified) have lower energy consumption compared to the proposed classical sequence. The results of the simulations indicate that better results are obtained with the extractive distillation using a dividing-wall column, achieving around a 50 % reduction in energy consumption and a 58 % reduction in CO 2 emissions. [ABSTRACT FROM AUTHOR]