... periphery. Configuration and Principle: 1. This kind of sludge scraper consists of drive, scum launder, accessory bridge, rake skimmer, ... scum scraper, scum baffles, sludge scraper, effluent weir, central bearing seat and influent well. ... 2. As the accessory bridge rotates, the scraper thereunder scrapes the sludge along the inclined tank bottom to ...