To make it possible to dredge lightweight sludge easy to spread around the circumference without contaminating surrounding environment by surrounding the whole circumference other than a grasping side of a sludge collecting wing to make it in a storing state.
A sludge collecting device is constituted of ventilating pipe 1, porous pipe 2 on the circumference thereof, sludge collecting wing 21 mounted to the porous pipe 2, upper semicircular cover 3 and circular arc door 4. Two sets of sludge collecting devices are arranged in parallel. The upper semicircular cover 3 surrounds an upper half of rotational range of the sludge collecting wing 21. Disk-like end face covers having the same diameter as that of the sludge collecting wing 21 are mounted to the end faces on both sides of the upper semicircular cover 3. The circular arc door 4 surrounds approximate 1/4 of the lower part in the rotational range of the sludge collecting wing 21 and, at the same time, it is opened. Screens 5 are arranged to the outside of the circular arc door 4 in a state to make it possible to cover the front thereof when it is opened. Accordingly, when sludge is dredged by toration of the sludge collecting wing 21, sludge is not spread over the circumference.
MAEDA YOSHIAKI
MIYANAKA KATSUNORI
