PURPOSE: To reduce cost for daily work by allowing a hollow central shaft of a sludge scraper to have a function of an air-lift pump.

CONSTITUTION: A central shaft 11 of a sludge scraper is made hollow and an air blowing pipe 16 is provided to the bottom of the central shaft 11. When the central shaft 11 is driven, sludge is discharged from an air/sludge discharging port 7 provided in the radial direction of the central shaft. The sludge is conducted through guides 8, 12 to a sludge receiver 9 and then transported to a predetermined part through a sludge discharging pipe 10. The device serves as a sludge collecting device and also as a sludge lifting pump, therefore, installation of conventional sludge transporting pump is no more necessary, and the cost is reduced as compared to conventional system.