Abstract: A sealed tank includes a concrete footing, a steel or concrete shell ring and a sealed and corrosion-resistant dome having a double membrane. There is an inner membrane delimiting, with the surface of the liquid effluent contained in the shell ring, a sealed chamber intended to receive biogas that results from the methane fermentation or from a corrosive environment. An outer membrane envelopes the inner membrane and which, when pressurized, applies a given pressure to the volume of biogas or of corrosive environment contained in the chamber.

Abstract: The invention concerns a device for recuperating floating materials in sedimentation tanks in installations treating effluent water. The invention is characterized in that it is in the form of a rotary syphon implanted above the tank at the end thereof and comprising an immersed discharge pipe, including a longitudinal slot and closed at one end and open at the other, an immersed bucket welded on said discharge pipe, over the whole length thereof, and a gear motor periodically driving in rotation over 360° the discharge pipe bucket assembly such that the floating materials are recuperated at each rotation by said bucket whereof the position relative to the immersed pipe is determined so that the floating materials are discharged into said pipe through its longitudinal slot then evacuated by gravity through said immersed pipe open end.