... tank 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 ... the accessory bridge rotates, the scraper thereunder scrapes the sludge along the inclined tank bottom to a central pit. The ...