Abstract: An activation plant for the treatment of waste water by the activated sludge method is disclosed wherein the plant has an outer, annular activation tank, a concentric, inner, funnel shaped secondary sedimentation tank, and a rotating aeration bridge rotating about the central axis. The return sludge, excess sludge, and floating sludge chambers, and the associated pumps, are provided in a central shaft that is the central axis for the concentric tanks. The floating sludge chamber is supplied by an annular trough circumscribing the central shaft. Clean water is removed through a conduit in the central shaft. The central shaft, chambers, and aeration bridge are supported by at least three rectangular tubes that are mounted on the wall of the secondary sedimentation tank and extend radially from the conduit for clean water in the central shaft. The rectangular tubes provide a flow space for clean water from the activation plant and are connected to outlet troughs for collecting the clean water.

Abstract: A method for the treatment of wastewater wherein the turbidity level of the wastewater is monitored to control the operation of the aerating units, while simultaneously, the oxygen concentration in the aerating tank is monitored to control the staging of the aaerating units between the maximum and minimum turbidity levels.

Abstract: An apparatus for introducing gases in the form of fine bubbles into a fluid is described, in which a diffuser pipe for a perforated distributor hose is mounted on a gas supply pipe. The diffuser pipe is constructed in one piece, extends transversely across the gas supply pipe, and is attached to the same by means of clamping elements. An opening for the passage of the gas is provided between the diffuser pipe and gas supply pipe. A pair of plugs positioned in the diffuser pipe define a flooding chamber at each end of the pipe and a gas-carrying chamber positioned medially therebetween. The apparatus is particularly suitable for the aeration of activation tanks for waste water.

Abstract: Apparatus for biologically treating sewage in an elongated circulation tank having a central partition extending along the longitudinal axis thereof thereby dividing the tank into two parallel flow channels connected together at opposite ends, aerators rotating about a perpendicular axis located along said longitudinal axis so that the sewage may be forced into a circulating flow about the perpendicular axis and about the partition. The circulating flow about said perpendicular axis thereby being decelerated and the sewage circulating about the partition being guided to and away from the rotating aerators with the full cross-section of the flow channels.

Abstract: A process for physically and biologically purifying sewage. A combination filter-biofilter containing a bed of artificially aerated filler material is used. The sewage is preliminarily clarified and distributed evenly over the filler material and is caused to flow through the latter for a limited time until the sewage has coated the surfaces of the filler material with sludge and microorganisms to an extent that the passage of air through the filler bed is substantially decreased because of encrustation of the interstices of the filler material. At this point the flow of sewage through the filler material is halted and the bulk of the sludge is removed from the filler material by turning the same over with air. Then, the flow of sewage through the filler material is reinstituted.