PURPOSE: To produce hydrogen while suppressing the generation of CO2 by a method wherein a methane fermentation blocking agent is preliminarily added to a methane fermentation tank and org. sewage or sludge is subjected to vacuum fermentation treatment to produce hydrogen and the culture treatment of photosynthetic bacteria is performed under a bright anaerobic condition using purple bacteria while CO2 is supplied.

CONSTITUTION: In treating org. sewage or sludge in a methane fermentation tank 2, a methane fermentation blocking agent 1' is preliminarily added to the tank 2 and org. sewage or sludge is subjected to vacuum fermentation treatment in the tank 2 to produce hydrogen, and further subjected to the culture treatment of photosynthetic bacteria under a bright anaerobic condition using purple bacteria while CO2 is supplied to further produce hydrogen. By this method, pollutants are decomposed to be converted to hydrogen being clean energy. Further, the excessive bacterial cells propagated in a photosynthetic bacterial culture tank can be converted to feed of livestock and poultry and/or valuables, thus a regional mass circulating system can be constituted.