Method for acquiring denitrified carbon source by fermenting surplus sludge

The invention relates to a method for acquiring a denitrified carbon source, particularly a method for acquiring a denitrified carbon source by fermenting surplus sludge. The method comprises the following steps: 1. carrying out ultrasonic pretreatment on surplus sludge, and fermenting; and 2. aerating the supernatant generated after fermentation, and treating the supernatant by a guano process, wherein effluent water of a reaction tank is the denitrified carbon source acquired by fermenting surplus sludge. The raw material adopted by the method is waste in municipal sewage plants, and therefore, the invention achieves the purpose of changing waste into resources; sludge generated in the sewage plants is treated on the spot to produce a carbon source, thereby saving the transportation expenses; surplus sludge after fermentation is converted into harmless substances, the amount of the sludge is reduced, and the surplus sludge can be further composted or fermented to produce methane or can be landfilled, thereby facilitating the subsequent treatment and lowering the cost; when being used as a carbon source, the generated sludge supernatant has the advantages of high content of short chain fatty acids and high C/N ratio; and the effluent water of the reaction tank can be directly transmitted into a denitrification reaction tank and used as a carbon source.