PURPOSE: To permit scum to be accurately scraped and collected at a predetermined place by a method wherein sludge scraping plates are securely provided at predetermined intervals along and between a pair of bendable endless means passed around a pulley set.

CONSTITUTION: When a sewage treating equipment is placed in operation, a sludge scraping device 30 is driven in the settling pond 20 and a scum scraping device 50 is then driven by the power elicited from the endless chains 35 of the sludge scraping device 30. Since the sewage runs into the settling pond 20 from the entrance opening of the front wall 22 thereof, flows from upstream to downstream and is discharged from an exit opening of the rear wall 23 thereof, the sediment is collected in a sludge collecting pit 24 by a sludge scraping plate 36 of the sludge scraping device 30. On the other hand, the scum 27 floating on the water surface 26 is carried to a scum gutter 25 by a scum scraping plate 57 of the scum scraping device 50 and discharged therefrom.