Effects of Alkali and Steam Coupling Pretreatment on L-lactic Acid Yield in Vinasse Fermentation

Vinasse has large components in lignin and cellulose, in order to make cellulase utilize them efficiently and increase efficiency of complex use of wastes, three kinds of pretreatment were experimented to vinasse, containing simple alkali, simple steam and alkali and steam coupling. The results show that after simple alkali and simple steam pretreatment, L-lactic acid yield of vinasse fermentation are 7.25g/L and 10g/L respectively, but after alkali and steam coupling pretreatment, the L-lactic acid yield increases significantly, reaching 26.25g/L. It means that alkali and steam cooperated with each other well. The vinasse fermentation with alkali and steam coupling pretreatment to produce L-lactic acid could minimize vinasse wastes, which has great benefits to circular economy and environmental sustainability.