Abstract: Disclosed is an apparatus for the intermittent aeration of sewage or sewage-activated sludge mixtures. The apparatus is adapted to be disposed below water level and consists of a horizontal air distributor in the form of a pipe jacket closed tightly at both ends except for an aperture for the air supply, and which, in the area of its two opposite lateral longitudinal edges, includes apertures for the passage of air. The apparatus further includes an elastic air distributing foil covering the apertures for the passage of air and the upper portion of the pipe jacket located between the apertures. The foil is provided with air escape openings which are opened by the air supply to the pipe jacket and closed in case of interruption of the air supply by being sealed against the pipe jacket outside the area of the air passage openings.

Abstract: A device for cleaning of a screen located in a water conduit is provided h a screen rake which has a screen comb at one end thereof, the screen rake being mounted and driven by a chain to be guided in a path such that the screen comb cleans the screen, deposits the screenings in a bin and returns to clean the screen again in a continuous and non-interrupted fashion. The path is formed by a number of connected angle bars which are curved in shape and which are placed between a number of chain wheels around which the chain is wrapped for movement thereover. The screen rake is pivotably connected at the end opposite to the screen comb to the end of a hinged support, the hinged support being pivoted around a stationary bearing and having a counterweight at the other end thereof.

Abstract: A device in the form of an air distributor container is provided for effecting intermittent aeration of waste water, with several of such containers being arranged beneath the water level and connected with an air intake. Each container comprises a tube-like support and an air distributor foil covering such support and having fine air exit openings therein which are opened during the aeration process by the air introduced through the intake, and which close once the air intake is discontinued. Each container comprises an oval barrel jacket, serving as the support and having upper and lower outwardly arched walls. A plurality of lateral air passage openings are located in the upper wall of the barrel jacket and extend along opposite longitudinal edges thereof. Cover plates air-tightly close opposite ends of the barrel jacket, and one of the plates contains an air intake opening.

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.