Research on the Recycling of Distillation Waste in Ethanol Fermentation from Food Waste and Its Influence

Ethanol fermentation from food waste could reduce the solid waste pollution and realize energy utilization. In order to decrease distillation waste, the recycle of such waste was adopted in ethanol fermentation. It demonstrated that such treatment could only last for four times due to the existence of side products. The distillation waste would gradually reduce ethanol concentration and sugar utilization ratio, lactic acid would be accumulated to 8 g/L, and salinity would be accumulated to 10 g/L, pH decreased to less than 3.5. Three-dimensional fluorescence analysis showed protein-type substances, microbial metabolism type substances, and humic substances were accumulated during the recycling. In order to resolve such problems, addition of protease was chosen in this research. The recycling time could enhance to seven times and the highest ethanol concentration was 35 g/L, the lowest ethanol concentration was 20 g/L. The recycling of distillation waste could save water resource, reduce wastewater discharges with high COD lees and reduce the cost. Which provided a new way for the clean production of bioethanol production from food waste.