Return sludge flow clarifying basin

The utility model discloses a sludge return sedimentation tank. The sludge return sedimentation tank is characterized in that a mixing area and a flocculation elevating area are arranged in an upper reaction area, a mixing and blending machine is arranged in the mixing area, an elevating mixer and an accessorial stainless-steel barrel body thereof are arranged in the flocculation elevating zone, a baffle plate system is arranged between a filtering area and an inclined-tube water outlet area, a plug-flow type concentrated sludge scraper is arranged in a sludge discharging area, a sludge return pipe is externally connected with the sludge discharging pipe and to a water inlet pipe, the sludge return pipe is provided with a return sludge pump, the sludge return pipe is also communicated with the external world, and medicament adding points are respectively arranged in the water inlet pipe and the main tank body. The sludge return sedimentation tank has the advantages that the indicating role of the biodegradati