Center water inlet type auxiliary flow sedimentation tank

A center water inlet type auxiliary flow sedimentation tank comprises a round tank body and a center water inlet pipe, a sludge tank is arranged in the center of the tank bottom of the round tank body, the center water inlet pipe is vertically arranged in the center of the bottom face of the sludge tank, a water outlet is formed in the side wall of the upper end of the center water inlet pipe, and a water inlet communicated with the center water inlet pipe is formed in the center of the tank bottom of the sludge tank. A sludge discharge port is formed in the tank bottom between the side wall of the sludge tank and the central water inlet pipe; an annular overflow groove is formed in the upper end part of the inner side surface of the circular pool body; an overflow outlet is formed in the side wall of the annular overflow groove; sewage in the sedimentation tank enters from the lower end of the central water inlet pipe and slowly flows into the sedimentation tank along the radial direction of the central wate