Abstract: Apparatus for treating and dewatering of sludge taken from small-scale sewage treatment plants. The apparatus, which preferably is mounted on a vehicle, incorporates chamber-type units for dewatering, which can be connected by way of feed and return pipes, controllable valves, and pumps that can be switched on and off. A dewatering vessel with filter walls and separate sludge and filtrate chambers is connectable with a sludge chamber and a filtrate chamber, respectively, of a second dewatering vessel by way of joining pipes comprising at least one feeding pump and one controllable valve each, a radiation chamber arranged in the filtrate return pipe of one of the dewatering vessels, and a stone trap arranged in one other sludge feed pipe.