Sewage treatment system utilizing primary sludge fermentation

The invention provides a sewage treatment system utilizing primary sludge for fermentation. The system comprises: an anaerobic reactor comprising anaerobic zones and aerobic zones, wherein the aerobic zone is internally provided with an aeration system, and a water inlet zone beside the anaerobic zone is provided with a stirrer; a post-settling tank connected with compartments, wherein a supernatant overflowing from the top of the compartment is discharged into the post-settling tank as effluent, and settled concentrated sludge returns to the inlet of an anti-anaerobic reactor through a sludge reflux pipe to be subjected to backmixing; and a denitrification reactor, wherein the upper portion of a fermentation reaction area is connected with a water storage tank, water flow and primary sludge are subjected to fermentation and denitrification reaction so as to remove nitrate nitrogen in influent, and water in a water outlet tank flows back to the anaerobic reactor through a reflux pipe. The system has the advan