Effects of distillery waste recycling on open ethanol fermentation from kitchen garbage and technological enhancement

Based on the previous studies, in order to reduce the distillery waste form ethanol fermentation, the distillery wastewater of ethanol production from kitchen garbage was recycled in this study. Particularly, the accumulation of the by-product during the fermentation and their effects were investigated. The results indicated that ethanol fermentation was inhibited obviously by full-recycling distillery wastewater without treatment. After 4times full-recycling, ethanol production was decreased from 28.4 g/L to 2.56 g/L. With the increasing recycling times, lactic acid, SS, DS and salinity were accumulated to 5.45, 64.7, 99.5 and 12.3 g/L, respectively. In order to improve the recycle times, 2/3 partial-recycling mode and flocculation full-recycling mode were utilized. During 7times of distillery wastewater recycling, the ethanol productions maintained at the range of 25.5~35.5 g/L for 2/3 partial-recycling mode. While for flocculation full-recycling mode, the ethanol production maintained at the range of 12.2~32.4 g/L. 2/3 partial-recycling mode was superior to flocculation full-recycling mode. In future, the combination of the two recycling methods should be considered for further improving the distillery wastewater recycling system.