Abstract
A new reactor combined with a self-agitation baffled reactor and a fixed bed was designed in order to develop a compact and high efficient methane fermentation system for food waste disposer. The performance of the reactor was evaluated through a long-term experiment with a mixture of food materials under a thermophilic condition (55°C). Influent total solid (TS) level of the substrate was controlled at approximately 4% assuming that a highly diluted food residue was provided to the reactor; the food waste was condensed after a disposer. Stable fermentation was successfully achieved at a volumetric CODCr loading rate from 2.3 to 12 kg/m3/day. It was confirmed that removal rate of organic matter in the influent was larger than that using a completely mixed reactor with semi-continuous flow because of a filtration effect by the fixed bed between the sludge in the reactor and effluent. More methane gas per input TS was produced under the thermophilic condition than mesophilic condition at a volumetric CODCr loading rate over 6 kg/m3/day. It was concluded that the new reactor was applicable to methane fermentation of food residue that has been subjected to a disposer and condensed system.
