Abstract: A wastewater orbital treatment system includes an elongated racetrack-like tank containing a central partition wall. A surface aerator is mounted adjacent to at least one end of the partition wall to both aerate and propel the mixed liquor including biomass around the orbital tank. An aerobic zone for BOD and ammonia oxidation is provided in an upper layer of the moving volume of mixed liquor and an anoxic zone for reduction of NO.sub.x from the aerobic zone, by anoxic respiration by the biomass, is provided in a lower layer of the moving volume of mixed liquor. An imperforate horizontal baffle is provided under the surface aerator so as to prevent dissolved oxygen in the aerobic zone from entering the anoxic zone. The NO.sub.x from the aerobic zone is introduced through a free interface of the two vertically displaced zones downstream of the baffle.

Abstract: The apparatus of the present invention is a cleaning system to be employed in the clarifier. A track is mounted to opposing sides of the clarifier. A scraping blade spans the two rails. A mechanism connects the two ends of the blade to the tracks and provides for stepwise movement of the blade bidirectionally within the clarifier. Movement of the blade over slots found in the clarifier bottom results in displacement of sludge from the clarifier back into the orbital ditch. The moving mechanisms are preferably located adjacent the clarifier floor. The scraping blade moves in stepwise motion over each of the slots, displacing sludge through such slots. At the same time a suction header, with inlets on both sides of the blade, allows some of the sludge to be suctioned from the bottom of the clarifier and removed from the orbital ditch system.

Abstract: A thickener well is provided in one end of a digester orbital ditch having a pair of channels and an elongated center partition spaced from a pair of ditch endwalls, the overall ditch forming a basin for digestion of wasted sludge. A curved endwall of the ditch provides a common curved top outer peripheral wall of the thickener well. The remainder of the well has a cylindrical configuration integral with the orbital ditch bottom and extending downwardly therefrom to a position below the horizontal plane of the ditch bottom. A sludge raking structure is positioned at the bottom of the well for periodically raking settled sludge into a sludge outlet at the bottom of the well. A surface aerator is provided between and spaced from the other ditch endwall and a juxtaposed end of the partition or other aeration apparatus mounted in a channel(s) to aerate and propel a liquid-solids sludge mixture wasted from a secondary treatment apparatus and fed into the orbital ditch.

Abstract: A combined oxidation orbital ditch and intraclarifier has the intraclarifier in the form of an elongated clarifier vessel positioned on the top of a section of the center partition between the ditch sidewalls so that the overall clarifier vessel extends laterally into both of a pair of flow channels formed between the ditch sidewalls and the center partition but is spaced from the ditch sidewalls so as to minimize impediment of the mixed liquor flow being treated in the channels. A gated inlet below the flow surface is provided in the one half of the bow of the vessel facing into the mixed liquor flow for diverting a portion of the flow into the clarifier. That flow portion is distributed over the entire width of the vessel and arrested in flow velocity so that settling of sludge can be performed downstream in the vessel.

Abstract: An improved wastewater aeration and mixed liquor pumping arrangement for an orbital-type actuated sludge purification method includes the addition of a radial flow impeller on a shaft extension below the normal surface aerator. Both the combined radial flow impeller and surface aerator are positioned with respect to an end of a partition wall forming the flow channels of the orbital system such that both the impeller and the aerator pump the mixed liquor in the same direction, so that the mixed liquor is moved at a sufficient velocity through and around the various channels and returned. The radial flow impeller is positioned adjacent to the bottom of the orbital channel and enhances the propulsion of the mixed liquor along the bottom of the channel thus permitting deeper channels with attendant concrete and land area savings in constructing the system.

Abstract: A dissolving tank for dissolving a large amount of gas in a liquid and including a generally horizontally disposed tray (28) (29) mounted within the tank (2) (21) to divide the tank (2) (21) into an upper reaction zone (36) and a lower discharge zone (38). The tray (28) (29) has formed therein both a central opening (34) (35) for fluid communication between the discharge zone (38) and the reaction zone (36) and peripheral openings (32) (33) which allow any liquid which collects on the tray (28) (29) to flow from reaction zone (36) to discharge zone (38). The dissolving tank further includes liquid feed means (10) positioned within the tank (2) (21) below the tray (28) (29) to discharge liquid upwardly through the central opening (34) (35) of the tray (28) (29) and into the reaction zone (36). The dissolving tank further includes liquid distribution means (14) mounted within the tank (2) (21) above the tray (28) (29) and having flared sidewalls (15) and a vertically-oriented distribution orifice (16).