The machine is suitable for large and medium-sized radial flow the secondary sedimentation tank sludge and slag removal. The machine is the center buttress the double (single) peripheral drive, the drive torque, energy saving. The water and mud of the center, surrounding drainage, to ensure uniform flow, the use of the level difference between self-priming mud. With overload protection devices, control and computer networking. Work, the sewage by the center buttress spread through the draft tube, a mixture of coarse particles by sedimentation after the formation of sludge in the bottom layer, the proportion of light floating on the surface, working bridge in the peripheral drive machinery, driven by along the center bearing slow rotation, driven by scraping arm scraper sludge layer sewage weeks scraping mud hole to the center set to discharge pool scum scraper along the draft tube will float on the liquid surface scum thrown pool slag bucket within the week, and discharged outside the pool.