Patent ID: 8802406

Claim:
A process for the production of methane, ethanol and butanol using three separate fermentation steps comprising: a) first fermentation step comprising fermenting initial feedstock to anaerobic fermentation in the presence of acetogenic bacteria, further comprising a mixture of bacterial strains, at a pH below 6.0, at a temperature in the range 20 to 70 degree C., converting said initial feedstock to a product predominantly comprising acetic acid and butyric acid; wherein ratio of acetic acid to butyric acid is at least 2:1; treating said product predominantly comprising acetic acid and butyric acid to separate a solution comprising the acetic acid and butyric acid by: (i) separating residual solids; and (ii) separating bacteria; optionally pasteurizing; optionally sterilizing said solution comprising the acetic acid and butyric acid; b) second fermentation step comprising fermenting in the presence of solventogenic bacteria said solution comprising the acetic acid and butyric acid from step a) to form ethanol and butanol; c) third fermentation step comprising a portion of said feedstock to said first fermentation step is anaerobically digested by a methanogenic bacteria to produce methane; optionally a portion of said solution comprising the acetic acid and butyric acid is anaerobically digested by a methanogenic bacteria in said third fermentation step to produce methane.