Abstract
This project developed a small methane fermentation system. To decrease the energy consumed running the reactor, a hot spring was used to heat the reactor, which used Leftover food brought by tourists. To construct this system, we determined how much Leftover food the tourists produced, whether tourists would put their Leftover food in the reactor, and the optimum conditions for producing gas via methane fermentation without pretreating the materials. The amount of food garbage per capita per day was about 300 g, of which 50% was rice. There were 24 - 48% more Leftovers from party type dinners, females, and those older than 70 years. Of the tourists, 72% would carry Leftover food from the ryokan to the reactor, which was a 10-minute walk away. The model tests indicated that the best hydraulic retention time (HRT) was around 10 days, and it performed the same as the standard methane fermentation treatment, which included pretreatment. Using Leftover food from 20 - 30 people per day would produce >1.4 m3⁄d of methane gas, whichwould Light the gas Lamp for about 8.5 hours. This system would reduce 669 MJ of energy and CO2 in waste by 100 kg per ton.
