Optimization of the Medium and Process Parameters for Ethanol Production from Kitchen Garbage by Zymomonas Mobilis

Plackett-Burman design was employed to screen 13 parameters for ethanol production from kitchen garbage by Zymomonas mobilis in simultaneous saccharification and fermentation. The parameters were seven enzymes for the fermentation, four kinds of nutrition salts, and two physical-chemical parameters. Only the protease and glucoamylase were determined to be significantly affecting factors for ethanol production. As a follow-up, a single factor experiment was carried out to determine the optimum usage of these two enzymes. They both showed the optimum effect at the usage of 100 U/g. Then the optimization for physical-chemical parameters during the fermentation were determined as follows: the solid to liquid ratio was 1:0.5, the initial pH 5, the incubation temperature 35C, the inoculum size 10%, the culture time 40 h, and the corresponding ethanol yield was 53.40 g/L.