Two-stage fermentation process and assembly to generate hydrogen and methane from biological residues

摘要

In a two-stage fermentation process to generate hydrogen and methane from biological residues, the first stage generates gases from which hydrogen is removed, and a second fermentation stage in which methane is generated from first-stage biological residues. The first-stage reaction takes place at a temperature from 50 to 100[deg]C in the presence of a natural or selected micro-organism culture. The biological inputs contain a high proportion of starch, but a low proportion of nitrates and sulfur compounds arising from agricultural or industrial wastes and residues. Thy hydrogen generated from the first stage is continually drawn off from the reactor with carbon dioxide, from which it is then either separated by membrane or cryogenic process, or used in a high-temperature fuel cell. The fermentation process operates at pH 5-6. A proportion of the hydrogen stage residues is tapped and fed to the liquid de-watering phase. The process water is essentially used in a closed-circuit operation. Also claimed is a commensurate assembly.