A method for preparing methane from pineapple dregs or mango dregs through anaerobic fermentation

A method for preparing methane from pineapple dregs or mango dregs through anaerobic fermentation is provided. The method includes (1) weighing biogas liquid of a biogas project adopting kitchen waste as a raw material, adding the pineapple dregs or mango dregs into the biogas liquid, with the solid-liquid mass ratio being controlled to be 6:100, and the ammonia nitrogen concentration being controlled to be about 2000 mg/L, adjusting a pH value with ammonia water to 8.5-9.0, and performing anaerobic fermentation at a maintained fermentation temperature of 35 DEG C for 60 days to obtain an inoculum; (2) subjecting the product of the step (1) to solid liquid separation to obtain a liquid supernatant and a precipitate, controlling the ammonia nitrogen concentration of the liquid supernatant to be 1500-3300 mg/L, blowing the precipitate with a small amount of the liquid supernatant to fully disperse the precipitate, and mixing the liquid supernatant the ammonia nitrogen concentration of which is adjusted and the dispersed precipitate; and (3) adding the pineapple dregs or mango dregs into the mixture with the TS% being controlled to be 1-4%, and performing fermentation. The method does not need independent acidification pretreatment, and can ensure successful biogas fermentation under conditions of enough volume loads and no increase of the volume of a fermentation tank. The method does not need a special additive.