PURPOSE: A titled apparatus of a relatively small size which is combined with respectively n units (n≥0) of rotary drum type separators and dehydrators and can efficiently make sludge of low water contents by precipitating and separating a large amount of suspended water.

CONSTITUTION: In order to separate mud water and excavation, etc., the 1st, 2nd separators of resembling main construction are combined respectively in, for example, 2, 1, 1 units. Raw water and coagulants are filled from a pipe 4 into the precipitating chambers 119W122 of the 1st separator 1 and the supernatant is discharged through the holes 118 of annular baffle plates 117 and discharge holes 104. The solid particles etc. settle in the grooves between spiral vanes 106. When the drum rotates, the precipitate S is sent toward the end plate 103, ascends by entering the grooves between scraping vanes 108 and falls from above the partition plate 113 onto the guide plate 112 on the outside circumferential surface of a circular cone body 111. Before this, the water W falls from the outside circumferential part of the porous shell cover 110 into the chamber 119 with a blind shell cover 124 for prevention of agitation. The precipitate S is further treated similarly in the 2nd separator 2 and dehydrator having no pipe 4 and plates 117, 124 and of larger discharge hold diameters.