Lactic acid production from sugarcane bagasse by an integrated system of lignocellulose fractionation, saccharification, fermentation, and ex-situ nanofiltration

Selective sugarcane bagasse (SCB) fractionation was conducted to produce cellulose-rich material for separate saccharification and fermentation to lactic acid. The highest glucose yield of 87.1% based on the polysaccharides in treated SCB was from a 2-step acid ethanolysis/alkaline peroxide pretreatment. The yield of lactic acid due to fermentation by Lactobacillus casei from SCB hydrolysate in a 3-L bioreactor was about 21.3 g/L after 120 h with the productivity of about 0.63 g/L h. For lactic acid separation, the low flux nanofiltration membrane showed higher performance in comparison with the high flux membrane. Using nanofiltration with low flux membrane, lactic acid was efficiently separated from the fermentation broth with glucose rejection of about 93.28%. The selectivity of the low flux membrane for separation of lactic acid and glucose in fermentation broth at 6 bar was found to be 82.48.