Method for producing ethanol

1. A method for producing ethanol with a saccharide obtained from a biomass, comprising:

(a) performing a pretreatment process to the biomass;

(b) removing a solution comprising acetic acid, formic acid, furfural, and hydroxymethylfurfural from the pretreated biomass;

(c) dispersing the pretreated biomass in water to form a biomass slurry;

(d) obtaining the saccharide by degrading cellulose and/or hemicellulose contained in the biomass slurry using a cellulase and/or a hemicellulase;

(e) adding the solution comprising acetic acid, formic acid, furfural, and hydroxymethylfurfural to the saccharide;

(f) preparing a mixed solution comprising the saccharide and the solution of (e), wherein a total concentration of the acetic acid, the formic acid, the furfural, and the hydroxymethylfurfural contained in the mixed solution is 1000 ppm to 4500 ppm; and

(g) adding a microorganism to the mixed solution to ferment the saccharide with the microorganism, thereby producing ethanol, wherein the microorganism is yeast, and wherein the biomass is selected from the group consisting of wood, grass, and agricultural residues.

2. The method for producing ethanol of claim 1 , wherein the solution of (e) is a liquid waste produced by performing a steam explosion treatment or a dilute sulfuric acid treatment on the biomass.