Conventionally, disposal of food waste such as garbage and of agricultural and livestock waste has become a serious social issue. To this point, the development of biomass treatment technology is wanted.
Responding to the movement, there is promoted the development of technology to treat organic waste using anaerobic fermentation. Conventional anaerobic fermentation is governed by the one aiming at the methane formation through the decomposition of organic matter. That type of anaerobic fermentation consists of two steps: the acid-forming step which conducts hydrolysis of organic matter such as carbohydrate, protein, and lipid to generate organic acid; and the methane fermentation step which decomposes the organic acid into methane, carbon dioxide, and water, (for example, refer to Patent Documents 1 to 3.)
The above acid-forming step is also called a hydrogen fermentation step because hydrogen is generated on decomposing the organic matter. The conventional anaerobic fermentation did not focus on the hydrogen, and the generated hydrogen has been consumed for use by the methane bacillus, reduction of electron acceptor and acquisition of energy by other bacteria, and so on.
In recent years, the hydrogen fermentation aiming at the hydrogen-generation through the decomposition of organic matter has drawn attention from the viewpoint of effective use of hydrogen as a clean energy, (for example, refer to Patent Documents 4 to 6.).    Patent Document 1: JP-A-2001-149983 (the term “JP-A” referred to herein signifies the “Unexamined Japanese Patent Publication.)    Patent Document 2: JP-A-2005-66420    Patent Document 3: JP-A-2005-125149    Patent Document 4: JP-A-2003-251312    Patent Document 5: JP-A-2005-13045    Patent Document 6: JP-A-2005-193122