Abstract: Fruit and vegetable wastes can be used as substrates for ethanol production by anaerobic fermentation, and the fermentation effect is affected by various factors. The pattern of ethanol production by anaerobic fermentation of mixed fruit and vegetable wastes under different conditions was analyzed, including hydrothermal pretreatment and sterilization, addition of cellulase, and inoculation of yeast. The results showed that the addition of cellulase and yeast were both beneficial to improve the hydrolysis effect of the system. The addition of yeast could effectively improve the ethanol production rate, while the addition of cellulase had a limited effect on the promotion of ethanol production in the system. The ethanol production rate of adding yeast and yeast with cellulase reached (0.164±0.040) g/g and (0.161±0.039) g/g per unit of fruit and vegetable waste organic matter, respectively, which was 34.23 times and 33.45 times higher than the control group. The fermentation pattern of fruit and vegetable wastes before and after hydrothermal pretreatment was similar, but hydrothermal pretreatment promoted the hydrolysis of the substrate and increased the yield of each product. The highest ethanol yield was obtained under the conditions of combined hydrothermal pretreatment and inoculation of yeast. Under this condition, the final concentration of ethanol could reach (16 672.09±2 304.85) mg/L with a yield of (0.233±0.032) g/g. Therefore, the addition of 0.5% mass of yeast could change the type of fermentation of the system, which made ethanol become the main product. The combined application of hydrothermal pretreatment and addition of yeast resulted in the highest ethanol yield.

Key words: fruit and vegetable wastes, anaerobic fermentation, ethanol, inoculation, cellulase