Abstract: An orbital wastewater treatment system generally including a tank assembly and at least one impeller in the tank assembly for moving mixed liquor under process about the tank assembly is provided with an wastewater inflow sensor, an impeller power meter, and a control unit for periodically and incrementally varying impeller speed and weir height in order to reduce energy consumption. Operating such a wastewater treatment system comprises flowing mixed liquor or wastewater into a treatment pool in the tank assembly, rotating the impeller within the pool to move the mixed liquor or wastewater, and adjusting, in concert, a rate of rotation of the impeller and a level or depth of the pool to reduce a rate of energy usage per unit inflow volume while maintaining at least one process parameter such as dissolved oxygen content substantially constant at a given level in the pool.

Abstract: A system and method are provided for removal of undesirable substances from a body of liquid. The system can include an aeration structure having a continuously inclined surface configured to provide an interaction of air bubbles against substantially an entire length of the continuously inclined surface while the air bubbles are moving toward a top of the body of liquid. The continuously inclined surface can be substantially submerged in the body of liquid. A bio-film of diverse bacteria colonies is disposed on the continuously inclined surface, and a high surface area-to-volume structure is located in proximity to the aeration structure, upon which a bio-film of bacteria colonies can be formed.

Abstract: An orbital wastewater treatment system includes a tank assembly, at least one impeller, a flow-diversion mechanism, an actuator, optionally at least one sensor disposed in the tank assembly, and a control unit. The tank assembly has an anoxic zone and an aerobic zone and passages between the two zones. The impeller is disposed in the tank assembly for aeration and for moving mixed liquor under process about the tank assembly. The flow-diversion mechanism is disposed at at least one of the passages between the aerobic and the anoxic zone. The actuator is operatively connected to the gate for regulating the flow state or configuration thereof in response to a signal generated by the control unit at least partially pursuant to a predetermined schedule and/or at least partially in accordance with input from the sensor.

Abstract: Disclosed is a system for treating wastewater. The system includes a microorganism clad structure positioned in a body of wastewater such that the microorganism clad structure is at least partially submerged in the body of wastewater. The apparatus also includes an aeration device, such as a propeller-type, surface mounted aeration device, supplying a horizontal flow of oxygenated water to the microorganisms attached to the microorganism clad structure such that the microorganisms may carry out a biological process.

Abstract: Disclosed is a system for treating wastewater. The system includes a microorganism clad structure positioned in a body of wastewater such that the microorganism clad structure is at least partially submerged in the body of wastewater. The apparatus also includes an aeration device, such as a propeller-type, surface mounted aeration device, supplying a horizontal flow of oxygenated water to the microorganisms attached to the microorganism clad structure such that the microorganisms may carry out a biological process.

Abstract: An integrated oxidation ditch comprises a number of oval channels. There are two or more circular zones in the central island of the oxidation ditch, wherein, the two circular zones are tangential to the inner wall or share the inner wall with an adjacent channel. Wastewater of different zones is connected with others. The center island is used sufficiently in the oxidation ditch and all the channels and the deposition zone or the deposition zone and an anaerobic zone, inner/outer re-circulation zone are integrated together. So the oxidation ditch improves space utilization efficiency and reduces the land and cost.

Abstract: An orbital wastewater treatment system includes a tank assembly, at least one impeller, a flow-diversion mechanism, an actuator, optionally at least one sensor disposed in the tank assembly, and a control unit. The tank assembly has an anoxic zone and an aerobic zone and passages between the two zones. The impeller is disposed in the tank assembly for aeration and for moving mixed liquor under process about the tank assembly. The flow-diversion mechanism is disposed at least one of the passages between the aerobic and the anoxic zone. The actuator is operatively connected to the gate for regulating the flow state or configuration thereof in response to a signal generated by the control unit at least partially pursuant to a predetermined schedule and/or at least partially in accordance with input from the sensor.

Abstract: Disclosed is a system for treating wastewater. The system includes a microorganism clad structure positioned in a body of wastewater such that the microorganism clad structure is at least partially submerged in the body of wastewater. The apparatus also includes an aeration device, such as a propeller-type, surface mounted aeration device, supplying a horizontal flow of oxygenated water to the microorganisms attached to the microorganism clad structure such that the microorganisms may carry out a biological process.

Abstract: Disclosed is a system for treating wastewater. The system includes a microorganism clad structure positioned in a body of wastewater such that the microorganism clad structure is at least partially submerged in the body of wastewater. The apparatus also includes an aeration device, such as a propeller-type, surface mounted aeration device, supplying a horizontal flow of oxygenated water to the microorganisms attached to the microorganism clad structure such that the microorganisms may carry out a biological process.

Abstract: Disclosed is a system for treating wastewater. The system includes a microorganism clad structure positioned in a body of wastewater such that the microorganism clad structure is at least partially submerged in the body of wastewater. The apparatus also includes an aeration device, such as a propeller-type, surface mounted aeration device, supplying a horizontal flow of oxygenated water to the microorganisms attached to the microorganism clad structure such that the microorganisms may carry out a biological process.

Abstract: A high denitrification shared type Orbal oxidation ditch, pertaining to water treatment technical field, comprises an outer channel, a median channel, an inner channel, all of ellipse, and a secondary deposition tank. Wherein, the length of the outer channel is prolonged in the ellipse's major axis direction and the secondary deposition tank that is tangential to the inner wall or shares the wall with the outer channel is arranged between the outer and median channels. All the channels (the outer channel, the median channel and the inner channel) and the secondary deposition tank are integrated in the Orbal oxidation ditch, all of the anaerobic zone, regulation zone, hydrolysis acidifying zone, primary deposition zone, sludge outer re-circulation zone and wastewater inner re-circulation zone etc.

Abstract: A high denitrification shared type Orbal oxidation ditch, pertaining to water treatment technical field, comprises an outer channel, a median channel, an inner channel, all of ellipse, and a secondary deposition tank. Wherein, the length of the outer channel is prolonged in the ellipse's major axis direction and the secondary deposition tank that is tangential to the inner wall or shares the wall with the outer channel is arranged between the outer and median channels. All the channels (the outer channel, the median channel and the inner channel) and the secondary deposition tank are integrated in the Orbal oxidation ditch, all of the anaerobic zone, regulation zone, hydrolysis acidifying zone, primary deposition zone, sludge outer re-circulation zone and wastewater inner re-circulation zone etc.

Abstract: An aquaculture wastewater treatment system is provided including three wastewater treatment subsystems. The first subsystem is comprised of a fish raceway solids removal channel populated with relatively high densities of a detritivorous fish such as tilapia and/or carp, that have high potential as an efficient means of feeding on, and thereby, removing suspended solids and particulate matter that are present in the primary fish production effluent. The second wastewater treatment subsystem is comprised of an enhanced form of nitrifying reactor termed the Suspended Media Ammonia Removal Technology (SMART) biofilter reactor subsystem. This water treatment component consists of an open ditch bioreactor oxidation vessel in which water is circulated by means of one or more powered paddlewheels.

Abstract: Polluted waste waters are introduced into a tank (1, 100) in which a number of cavitation oxygenizers (5, 6, 11) are installed close and parallel to the bottom of the tank and divided into three types, one (5) that expels re-circulated water and air, a second (6) that expels water, air and sludge and foam sucked in from the upper region of the tank, both these two types suited to causing turbulence (F1, F2-F3, F4) of the polluted water within the tank, and a third (11) suited to cause a further turbulent motion of the polluted water.

Abstract: A water treating apparatus consisting of a water path having entrance(s) and exit(s) and ceramic grain(s) movably inserted in said water path is provided in the present invention. When water is put in said water path of said water treating apparatus, said ceramic grains may be moved and rolled by the pressure of said water flowing in said water path and said moving and rolling ceramic grains may disturb the flow of said water to intensify the effectiveness of water treatment by said ceramic grains.

Abstract: An apparatus for cultivating macrophytes grown on the water surface in a circular basin structure containing a channel of plant growth nutrients water spiraling from the basin structure periphery into the center of the basin structure and then back out again to the periphery. Two spiraling berms, constructed in parallel, define the single, continuous channel of water. A conveyor means is mounted on a rotatable arm that extends from the basin structure center to the basin structure periphery and rotates about the central support. The conveyor means moves laterally along the rotatable arm so as to remain in the center of the channel of water as that arm rotates. A portion of the floating macrophytes on the water surface is harvested one or more times each day and transported to beyond the periphery of the basin structure where the floating macrophytes are available for subsequent processing.

Abstract: A denitrification apparatus, for use in a wastewater treatment system having a mixed liquor source, is disclosed. The apparatus has at least two non-aerated continuous channels, connected in series. Wastewater flows from the mixed liquor source into the series of channels and then flows back into the mixed liquor source. In a preferred embodiment the inlets and outlets for each channel are arranged so that the flow into the channel is into the lower portion of the channel, and the flow from the channel is from the upper portion.

Abstract: The present invention relates to a novel apparatus for enhancing the nitrification of wastewater, and a method of its use. The present apparatus comprises the addition of a plurality of submerged, fixed support means to an activated sludge system. These support means act as supports for autotrophic nitrification bacteria and are disposed in the activated sludge system so that the wastewater is substantially free of carbonaceous waste by the time it reaches the support media. A circulation system is used to bring the wastewater into contact with the support media so that nitrification can occur.

Abstract: In an extended aeration wastewater treatment system having wastewater flowing into a retention basin so as to form mixed liquor within the retention basin, the treated mixed liquor flowing out of retention basin through a retention basin exit line to an external clarifier, a mixed liquor wasting system is provided, comprising a thickener tank, having a sidewall and a bottom; a waste line having a first end and a second end, the first end fluidly connected to the retention basin by connection to the retention basin exit line, and the second end fluidly connected to the thickener tank; a first flow control device, such as a pump, for continuously removing a portion of the mixed liquor from the basin at a desired constant flow rate through the waste line, positioned in the waste line; a sludge removal line having a first end and a second end, the first end fluidly connected to the bottom of the thickener tank, and the second end fluidly connected to a sludge disposal system; a second flow control device, such as

Abstract: In an extended aeration wastewater treatment system having wastewater flowing into a retention basin so as to form mixed liquor within the retention basin, a mixed liquor wasting system is provided, comprising a thickener tank, having a sidewall and a bottom; a waste line having a first end and a second end, the first end fluidly connected to the retention basin, and the second end fluidly connected to the thickener tank; a first flow control device, such as a pump, for continuously removing a portion of the mixed liquor from the basin at a desired constant flow rate through the waste line, positioned in the waste line; a sludge removal line having a first end and a second end, the first end fluidly connected to the bottom of the thickener tank, and the second end fluidly connected to a sludge disposal system; a second flow control device, such as a pump, for removing a concentrated portion of the mixed liquor from the thickener tank, positioned in the sludge removal line; and a return line having a first end

Abstract: A complete mix activated sludge basin is operated as a Sequence Continuous Reactor by cyclically aerating the mixed liquor to form an aerobic cycle at selected high dissolved oxygen levels, during which nitrification takes place, and cyclically mixing the liquor without aerating to form anoxic cycles at selected low dissolved oxygen levels, during which denitrification takes place. Field adjustments can be made by the operator in the dissolved oxygen levels and in the duration of the aerobic and anoxic cycles, whereby ammonia removal, nitrification, and denitrification can continue to be done efficiently during both summer and winter temperature conditions, during conditions varying from warm to cold inlet wastewater temperatures, during extreme variations in food supply, and during pronounced variations in biomass concentration and activity.

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: An oxidation ditch for biological aerobic treatment of wastewater having a velocity control system to establish an increased and more uniform cross-sectional velocity throughout the flow channel. The system includes a turning baffle member positioned in at least one of the end sections of the flow channel. The turning baffle member is provided with an end portion that has an upper edge that extends under a brush aerator located across an elongated section of the flow channel. The upper edge of the other portion of the turning baffle member extends above the surface of the flowing mixed liquor stream. The flow of the mixed liquor downstream of the brush aerator is unrestricted by flow baffles located in the flow channel.

Abstract: A compact waste treatment facility comprises an optional surge basin, an aeration basin, a settling basin, and a digester basin. The basins are interconnected in the order named for therewith providing a sequentially arranged waste treatment facility. Each of the basins is comprised of six integral walls which are substantially equiangularly disposed one to the other so that each basin is hexagonally shaped in plan. Each basin has a wall common with the basin interconnected therewith. Each basin has an assembly for supplying fluid treated therein to the next interconnected basin. An aerator is provided in the aeration basin for causing fluid flow thereabout.

Abstract: An oxidation ditch for circulating a waste water stream and having a channel formed by a continuous vertical outside wall extending upward from a bottom and having at least one section shaped to form a curved area into which a vertical turbine is operatively positioned and by a partition wall also extending upward from the bottom and positioned inside the outside wall with one of its ends adjacent the vertical turbine, the improvement of which comprises a baffle positioned in the channel upstream of the vertical turbine to minimize the mixing of the upstream waste water with the backwash created by the vertical turbine.

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 process and any of several pump/circulators provide selective rapid mixing of influent wastewater with the mixed liquor in the channel of an oxidation ditch and thereby provide maximized use of the entire volume of the channel. The pump/circulator is disposed at the beginning of the anoxic zone and preferably receives the influent wastewater. The oxidation ditch is preferably a barrier oxidation ditch or at least a baffle oxidation ditch in order to prevent backmixing.

Abstract: In an orbal wastewater treatment process including a plurality of concentric, annular basins or channels having surface aeration means, wastewater and recycled activated sludge are mixed in a first channel by a combination of the surface aeration means and introducing an oxygen-containing gas such as air into the lower portion of the zone under conditions which produce a complete mix reaction and sufficient oxygen is supplied to meet the biological oxygen demands of the mixed liquor. The gas is introduced, preferably by a plurality of fine bubble membrane diffusers, in the form of fine bubbles having a diameter of less than about 4 mm. The mixed liquor is sequentially oxidized in second and third channels by a combination of surface aeration means and introducing an oxygen-containing gas into the lower portions of the channels, preferably by fine bubble membrane diffusers.

Abstract: An apparatus for aerating fish ponds utilizes a cylindrical brush mounted for rotary motion below the top of a dam or headwall. Water passing over the dam and falling into a fish pond below the dam falls onto and over the cylindrical brush causing the brush to rotate. The rotating brush breaks up the falling water into droplets as the water passes through the brush bristles. Below the rotating brush, the water droplets fall through an air-water mixing zone where atmospheric oxygen is dissolved by the water droplets thus increasing the dissolved oxygen concentration of the water.

Abstract: An intrachannel clarifier for an oxidation ditch includes an enclosure positioned in the flow path of the oxidation ditch. This enclosure defines a perimeter wall which surrounds an internal volume made up of an upper zone, a middle zone and a lower zone. The cross-sectional area of the internal volume increases progressively from the lower zone to the upper zone. A water inlet port introduces waste water from the flow path into the lower zone, a submerged pipe in the upper zone removes clarified water from the upper zone, and sludge is actively removed from the middle zone via a sludge removal manifold disposed in the middle zone to reduce the residence time of sludge in the middle zone while maintaining a filter blanket of sludge in the middle zone.

Abstract: Operation of an intra-channel clarifier within a circulating sewage stream can be enhanced by flow adjusting vanes positioned within the sewage stream between the clarifier and channel wall, proximate to the clarifier sludge ports. In a preferred embodiment, the vanes are aligned perpendicular to the flow of the stream, on a vertical axis. The vanes are divided into an independently adjustable upper and lower portion which can be used to direct the sewage flow and alter the cross sectional area of the sewage stream in the vicinity of the clarifier. The rate at which sludge is removed from the clarifier is affected by the velocity of the sewage stream beneath the sludge ports as well as any turbulence or eddy currents which are produced.

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: A process is disclosed for treating food wastewaters by acidifying to a low pH, adding an alginate, and, preferably, adding lime to a pH of at least 7.0, without adding iron or aluminum to assist in coagulation and flocculation of the wastewater. A floc is formed at acid pH in some wastewaters and at neutral to alkaline pH in other wastewaters treated with lime. After recovery of the floc as a sludge, the process provides at least about 70% removals of Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD) at reasonable costs and with negligible formation of free fatty acids in the resulting sludge.

Abstract: For use in an activated sludge process, dual-baffle aerators for both vertically mounted surface aerators and static mixer-aerators are disclosed. These devices substantially prevent back-mixing of freshly aerated liquor into aerator intakes and provide directional propulsion. By connecting two or more such devices to form a barrier across the channel of an oxidation ditch, homogeneous aeration is provided to the mixed liquor. Barriered pump/aerator assemblies utilizing directional mix jet aerators (eddy jet) are also described. These devices can also be combined with dual-baffle aerators to furnish both propulsion and a selected degree of homogeneous aeration in a barrier oxidation ditch. An adjustably apertured barriered pump assembly is additionally disclosed for providing a selected balance between homogeneous aeration and/or mixing and heterogeneous aeration and/or mixing.

Abstract: Apparatus for increasing the efficiency of absorption of oxygen by biodegradable waste and particle break-up thereof, by introducing waste and gas, which may be air, into a collector under a highly agitated state, and agitating the air and waste under pressure in the collector by the impeller of a vortex type centrifugal pump as back pressure is provided to the collector. The collector is mis-matched relative to the impeller to increase the retention and mixing time of the air and waste in the collector.

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: An apparatus for aerating waste water comprising a surface aerator adapted to rotate about a vertical axis. A cap is disposed over the aerator and is modified to improve the operation of the apparatus. The waste water flows in a closed circuit and a partition is provided separating the parts of the circuit lying upstream and downstream of an aeration zone. The surface aerator is arranged in an aeration zone in the neighborhood of an end of the partition.

Abstract: A skimmer system is provided for structures having a floor, two side walls and at least one open end, the structure being semi-submersibly positionable in a moving liquid stream. The skimmer system comprises at least one side trough having a bottom, an interior trough wall and an exterior trough wall. The exterior trough wall is coincident with the interior side of one side wall of the structure and is provided with at least one opening communicating betweeen the interior of the trough and the exterior of the structure. The interior trough wall is provided with at least one opening communicating between the interior of the trough and the interior of the structure.

Abstract: Apparatus for treating waste water by the solids contact aerobic biological treatment process comprises a clarifier and a reaction basin in liquid communication with one another. In one embodiment, the reaction basin has an aerator which also circulates liquid through the clarifier by way of pipes arranged to collect liquid from the surface of the reaction basin and deliver it to a location adjacent a back wall of the clarifier. The clarifier has a bottom wall which slopes towards the reaction basin. Sludge particles in the liquid settle out in the clarifier and liquid discharged from the pipes flushes the settled biological sludge back into the aeration section of the reaction basin. In another embodiment the clarifier and reaction basin together form an oxidation ditch defining a closed loop. An aeration device continuously circulates liquid around the loop and through the clarifier.

Abstract: A submersible mixer support system for use in sewage treatment systems and the like has parallel tubular guide bars supporting at least one mixer stand unit having a slow rotation, large propellered mixer thereon. The mixer stand unit is releasably clamped to the parallel guide bars by clamping units each having a horseshoe-shaped resilient clamping block deformable when a clamping pressure is applied thereto by a preload assembly located remotely therefrom. The mixer support system facilitates removal and servicing of the various subassemblies located thereon.

Abstract: A submersible mixer support system for use in sewage treatment systems and the like has parallel tubular guide bars supporting at least one mixer stand unit having a slow rotation, large propellered mixer thereon. The mixer stand unit is releasably clamped to the parallel guide bars by clamping units each having a horseshoe-shaped resilient clamping block deformable when a clamping pressure is applied thereto by a preload assembly located remotely therefrom. The mixer support system facilitates removal and servicing of the various subassemblies located thereon. A guide system is provided in order to remove, inspect and reinstall the tubular guide bars.

Abstract: A reactor for waste water including a vessel 10 having two elongated outer channels 26, 28 sandwiching an elongated inner channel 30 with all the channels 26, 28 and 30 being connected to each other at both opposed ends thereof, a gate 64 at one of the ends 18 and movable between a first position isolating the channel 26 from the channels 28 and 30 and a second position isolating the channel 28 from the channels 26 and 30, rotors 32, 34 for each of the channels 26, 28 for aerating waste water in the vessel 10 and for causing the waste water to flow in the corresponding channels 26, 28 as well as the inner channel 30, and a pair of effluent outlets 98, 100, located at the end 18 and spaced to be on opposite sides of the gate 64, each selectively operable to withdraw effluent from the the outer channels 26, 28 on the associated side of the gate 64.

Abstract: A method and device are provided for improving the reoxygenation of water in line with dams. At the crown of the dam a plurality of studs are disposed which form a comb and cause thorough division of the overflowing sheet of water. This sheet of water undergoes a veritable disintegration which increases the air-water interface and causes an increase in the oxygenation of the overflowing flow.

Abstract: A turbulence control system is provided comprising a first baffle, fixedly connected across the interior of an intra-channel clarifier having side walls between the side walls near the point of entry of wastewater into the clarifier, the first baffle covering a desired portion of the cross-sectional flow area within the clairifier; and a second baffle, fixedly connected across the interior of the clarifier between the side walls downstream of the first baffle and covering a desired portion of the cross-sectional flow area left uncovered by the first baffle. The turbulence control system may also comprise at least one accumulation baffle, connected between the side walls and near the bottom of the clarifier, the accumulation baffle extending upward to a desired height within the clarifier, but not so high as to produce a flow velocity which would impede settlement of sludge within the clarifier.

Abstract: A jet aerator header assembly is provided for the deep oxygen contact duct of a partial, total, or non-barriered oxidation ditch having an endless channel. The header assembly may be vertically installed in the bottom of the contact duct or at an angle in the intake portion thereof as a mid-duct header assembly; it can additionally be installed in a horizontal position at the inlet of the contact duct as an inlet header assembly. Each header assembly comprises a liquid header, an air header, a plurality of jet aerators which are flow connected to both headers, stiffener plates which rigidly attach the headers to each other and to the jet aerators, and pipes connecting the headers to respective liquid and air supply lines. The mid-duct header assembly is slideably mounted within an access duct which is accessible from the surface.

Abstract: An improved barrier oxidation ditch is provided which has a channel portion for unaerated induced-flow and an inclined duct for aerated induced flow, whereby energy in the dammed-up momentum is more efficiently released. This induced-flow duct is inclided at 30.degree. to 60.degree. to the horizontal, preferably 45.degree., and is disposed upstream of, downstream of, or alongside of the circulator/aerator in the intake channel. The induced-flow duct is preferably rectangular in cross-section and may have its downstream wall formed by the baffle if it is downstream of the circulator/aerator. The induced-flow duct is connected at its lower end to the discharge duct to initiate a combined-flow portion thereof. This combined-flow portion has an upper side which may be a thin wall or may be a much thicker aerator bridge. A baffle may be mounted downstream of the inlet of the induced flow duct for selectively restricting the amount of unaerated induced flow.

Abstract: A side channel clarifier for use in wastewater treatment devices employing the circulation of water in a tank having a circuitous path for the purposes of aeration and biological digestion of wastes, wherein the clarifier is mounted in the wall of the channel so that the main flow of water in the tank is undisturbed, and that a portion of that flow is diverted into as quiescent clarification zone, where an inclined baffle collects settled sludge and returns that sludge to the main flow for further decomposition. Siphoning means are provided to ensure the return of a substantial portion of the sludge to the main flow before stagnation occurs and without disrupting the inflow of wastewater into said clarifier. Means are also provided to separate the clarified effluent for further treatment.

Abstract: Method and apparatus for aerating flowing water which includes a plurality of successive aerating chambers having divider baffles therein to direct the flowing water downwardly while introducing a flow of oxygen and water thereto and permit the oxygen level in the flowing water to be maximized.

Abstract: Apparatus for treating waste water by the solids contact aerobic biological treatment process comprises a clarifier and a reaction basin in liquid communication with one another. In one embodiment, the reaction basin has an aerator which also circulates liquid through the clarifier by way of pipes arranged to collect liquid from the surface of the reaction basin and deliver it to a location adjacent a back wall of the clarifier. The clarifier has a bottom wall which slopes towards the reaction basin. Sludge particles in the liquid settle out in the clarifier and liquid discharged from the pipes flushes the settled biological sludge back into the aeration section of the reaction basin. In another embodiment the clarifier and reaction basin together form an oxidation ditch defining a closed loop. An aeration device continuously circulates liquid around the loop and through the clarifier.