Method for recycling ethanol pulping waste liquor

The invention discloses a method for recycling ethanol pulping waste liquor. Efficient recycle of the ethanol pulping waste liquor is realized by using wheat straw ethanol pulping waste liquor as a raw material, using acetic acid as a pH regulator and using a combination method of reclaiming ethanol lignin by adjusting the solubility parameter of the ethanol lignin in the waste liquor and reclaiming ethanol and acetic acid by reduced pressure distillation. The method realizes zero discharge of the waste liquor, simple process, convenience in operation, low running cost, and low energy consumption. The reclaimed ethanol and acetic acid solution consists of about 61 volume percent of ethanol and about 5 volume percent of acetic acid, and the purity of the reclaimed ethanol lignin is 91 percent. When the reclaimed ethanol and acetic acid solution is recycled for digesting, the yield of the obtained washing ethanol pulp is about 51 percent, the Kappa value is about 33 percent, the crystallinity is about 61 percent, and the content of alpha-cellulose is 83.5 percent.