Abstract
Enegy recovery from small amount of food residue using methane fermentation technology was studied for on-site energy use with a high efficiency. Amount of food residue from one establishment by business activities was estimated to be less than 1 wet-ton per day. In a conventional methane fermentaion system, it was estimated that a required electricity to operate methane fermentation system is larger than an obtained electricity converted from biogas due to the small amount of food residue. It was suggested that new type of mthane fermentation system, whose digester tank has agitation without driving power and tanks are integrated by removing pumps, was necessary to decrease a required electricity to operate the system. In addition, it was more effective to apply co-digestion of food residue, oil and fats to new type of methane fermentation system in order to increase an obtained electiricity. Greenhouse gas emission per food residue weight for the case of energy recovery with new type of methane fermentation system was evaluated by comparing with the case of incineration or composting food residue.