Abstract: A container is supported floating in a liquid by floats; an inflow gate is loosely fitted about the container. The inflow gate has a sloping face for introducing liquid into the container. A discharge is provided for discharging the liquid accumulated in the main body bath. Floating substances collected on the sloping face of the inflow gate are raked and pushed into the main container by a raking machine arranged on the sloping face of the inflow gate and a pressure screw arranged on the sloping face of the inflow gate and a pressure screw arranged in the main container.