Patent ID: 8669083

Claim:
An integrated process comprising: fermenting sugars from a mixture to produce a beer; distilling the beer into the ethanol and a whole stillage; separating the whole stillage into a thin stillage and wet distillers grains; anaerobically digesting a first portion of the thin stillage comprising non-fermentable solids and organic acids to produce biogas and a biogas effluent; recycling a second portion of the thin stillage comprising fermentable solids as backset into the process and into a pretreatment apparatus prior to the fermentation step; and recycling the biogas effluent into the pretreatment apparatus prior to the fermentation step, wherein the process produces ethanol, biogas, and wet distillers grains and byproducts are recycled into the process at the pretreatment apparatus prior to entering the fermentation step and wherein the recycling results in zero discharge of byproducts.