Methane Fermentation of Bean Curd Refuse

The methane fermentation of bean curd refuse was studied in a 1 I reactor operated in a fed-batch mode with daily feeding using two kinds of methanogens. The objective was to examine the effects of substrate loading rate on methane yield and behavior of the product species. A unified approach was employed for the material balance between the substrate and product species based on elemental carbon content. The categorized product species included methane and carbon dioxide in the gas phase, soluble total organic carbons excluding volatile fatty acids, volatile acids, and the unconverted substrate in solid phase. Results indicated that the methane yield increased with substrate loading rate, reaching a maximum of 53.7%, which closely approached the theoretical yield of 55%. However, it was discovered that a critical substrate loading rate existed beyond which operation became unfeasible due to excessive accumulation of unconverted solids. The study underscores the potential of effectively utilizing bean curd refuse through methane fermentation to address environmental concerns associated with waste disposal.