Abstract: A method and apparatus for the treatment of waste water. The method comprises a primary sedimentation stage, an activation stage comprising high, medium and then low loading rate oxidation stages, a filtering stage and a clarification stage. All of these stages are performed in a single flat-bottomed parallelepipedal basin. The water treatment apparatus comprises a sludge recirculator (23, 24), an aerator (22, 25), a skirt (26), a filter (29) and a horizontal laminar flow clarifier (27). The clarifier is made up of a succession of inclined baffles (27a) joined together in pairs at their upper and lower edges. Sludge aspirator pipes (28) are provided adjacent the bottoms of the inclined baffles.

Abstract: The invention provides an aerator device for dispensing liquid in a gas phase by producing an upwardly-directed spray of the liquid from a tank. The device, which is intended to be submerged in a tank, comprises a motor-pump unit in the vicinity of the tank floor and a primary flared tube and a secondary flared tube coaxial therewith. The secondary flared tube is connected to a delivery nozzle by an intermediate duct, and the delivery nozzle is surmounted by an adjustable needle. The buoyancy of the whole assembly is ensured by a set of variably ballasted buoys which pivot at the end of support arms, and by an upper buoy concentric with the nozzle.