Abstract: In the submerged diffuser arrangement described in the specification, a plurality of submerged air diffuser arrangements are disposed adjacent to the bottom of in a body of wastewater to be aerated and connected an air supply pipe extending along the surface of the wastewater. Air is supplied from the air supply pipe through downcomers leading to the diffuser arrangements. The diffusers may be suspended from the air pipe above the bottom or they may rest on the bottom. In order to raise the diffuser arrangements to the surface of the wastewater for servicing, inflatable buoyant members are affixed to each diffuser arrangement or to the lower ends of the associated downcomers. The inflatable buoyant members are connected through tubing to valves from which air may be supplied under pressure, either from the air supply pipe or form a portable air compressor or a compressed air container or through an air pressure line leading from a remote air supply located on the shore of the basin.

Abstract: In the embodiments of the invention described in the specification, an arrangement for biological treatment of wastewater includes a basin with an aeration region and a clarification region separated by a movable wall having a passage between the bottom of the wall and the bottom of the basin. The aeration region includes a plurality of diffuser arrangements for aerating the wastewater and the clarification region includes a sludge removal duct and at least one turbulence generator for periodically stirring up sludge particles which have been deposited on surfaces of the clarification region remote from the sludge removal duct and recirculating sludge through the wall passage to the aeration region and permitting sludge to resettle on surfaces closer to the sludge removal duct. The movable wall may be positioned to include one or more diffuser arrangements from the aeration region within the clarification region.

Abstract: In the aeration reactor described in the specification, an aeration basin has two aeration cells separated by a dividing curtain and connected in series so as to normally receive wastewater in the first aeration cell and then pass the wastewater to the second aeration cell which is followed by a clarifier to separate sludge from the treated wastewater. A liquid level detector in the reactor responds to surges in the rate of flow of the wastewater through the reactor to redirect incoming wastewater and return sludge from the first aeration cell into the second aeration cell and isolate the first aeration cell to preserve active sludge in that cell.