Working principle: Self-priming sludge discharge using liquid level difference, scum scraper collection and removal device and overload protection device; the control system can be networked with microcomputer according to user requirements. It is mainly composed of drive mechanism, main beam, center rotating bearing, deflector, mud scraping system, slag hopper and flushing mechanism, articulated scraper rake, skimmer plate, skimmer bucket, outlet triangle edge plate, scum baffle, control box and other components. The supernatant is discharged from the outlet tank through the overflow weir plate, and the sludge scraper is scraped from the pool circumference to the central mud collection tank, and the water pressure in the pool is discharged out of the pool through the sludge discharge pipe. Driven by the peripheral drive device, the main beam runs at 2.0m/min linear speed along the top of the pool with the center rotating bearing as the axis. The lower part of the main beam is connected to the bracket, sludge scraper, etc. When the main beam rotates, the scum scraper skips the liquid level scum from the center of the pool to the pool circumference, and is collected in the hinged scraper area, the collected scum moves with the host around the pool to the skimmer bucket, and is scraped into the skimmer through the hinge movement of the scraper rake, and discharged to the outside of the pool.