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: Rammed building walls having an earth core and integral cement jackets are formed by placing a rectangular earth hopper within a rectangular wall moulding cavity that is defined by formwork members which are aligned with an underlying foundation. The hopper is filled with earth while outside of the moulding cavity and has a trapdoor as its bottom. The moulding cavity has a substantially greater width than the width of the hopper so that jacket cavities are formed on either side of the hopper. A pair of tiltable cement hoppers, filled with concrete or a sand and cement mix, are mounted on the earth hopper and are tiltably unloaded into the jacket cavities. The trapdoor is then released so that the earth slides downwardly and laterally, and the hoppers are lifted as a unit out of the moulding cavity while the earth fills a core cavity between the mix-filled jacket cavities. Both the earth and mix are then rammed simultaneously.

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: A nitrification-denitrification process is disclosed wherein a single flow-through and cyclically operated complete mix activated sludge basin, containing mixed liquor having a mean cell residence time of at least 15 days, is fed with wastewater and discharges treated wastewater to a clarifier while its contents are continuously agitated and cyclically aerated for approximately 3-9 minutes to form an oxic stage and then not aerated for approximately 3-9 minutes to form an anoxic stage. The treated and clarified liquor has ammonia contents no higher than 2.0 mg/l, nitrite contents no higher than 1.0 mg/l, and nitrate contents no higher than 2.0 mg/l. Approximately 99.9% by weight of the discharged sludge from the clarifier is returned to the complete mix basin, the remainder being waste activated 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: A process is described for treating a feed wastewater from a food preparation plant to recover substantially all of its fats and up to 50% of its proteins in a chemical float sludge which is selectively admixed with an absorptive bulking agent, such as sawdust, at a dry-basis weight ratio of 3-4 pounds of bulking agent to one pound of total sludge solids to produce a biomass mixture which is selectively dried and regulated in size to a maximum of 1/8-inch to produce a biomass fuel, characterized by a fuel value of approximately 11,000 Btu per pound, which is highly suitable for self-sustained burning in a gasifier-type suspension burner. After removal of the float sludge, the partially purified wastewater is aerobically treated with microorganisms to produce activated sludge, a selected portion thereof being recycled to the feed wastewater before admixing coagulation and flocculation chemicals therewith.

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: A process is described for producing an animal feed, comparable to feathermeal in properties and appearance, from two waste products: float sludge and activated sludge. The process uses a bulking agent for extracting excess fat from the sludges, particularly the float sludge, while a mixture of the sludges and the bulking agent is being stirred, heated, and dried. Blood, chicken litter, meat scrap, and the like can be substituted for activated sludge to provide protein. The bulking agent can be any material that can expose the sludges to air, that is capable of absorbing fat, and that can be separated from the dried and partially de-fatted sludges. Wood chips are the preferred bulking agent. Wood shavings, shredded cardboard, shredded newspaper, paunch manure, and the like can be substituted for wood chips as the bulking agent.

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: An improved barrier oxidation ditch is provided which has an inclined duct for the induced flow, whereby energy in the dammed-up momentum is more efficiently released. This induced-flow duct is inclined at 30.degree. to 60.degree. to the horizontal, preferably 45.degree., and is disposed upstream of, downstream of, or alongside of the circular/aerator in the intake channel. The induced-flow duct is preferably rectangular in cross-section and may have its downstream wall formed by the barrier if it is downstream of the circulator/aerator. It is connected at its lower end to the discharge duct to initiate a combined-flow portion thereof. An in-channel clarifier, disposed in the discharge channel so that its upstream wall is the barrier and its solid bottom is the ceiling of the combined-flow portion of the discharge duct, provides prolonged bubble retention time at maximum hydraulic pressure, whereby the efficiency of oxygen transfer is increased.

Abstract: A process is described for pumping and aerating the mixed liquor within the endless channel of an oxidation ditch by using a pump/aerator to form an aerobic zone which has a selectively located planar end, where an anoxic zone begins, and within which biological nitrification of NH.sub.3 -N occurs. A pump/circulator, to which inflowing raw wastewater and return sludge are fed, is located approximately at this planar end to provide point-source mixing of the wastewater and return sludge, whereby the five-day biological oxygen demand of the wastewater is oxidized within both the aerobic and the anoxic zones and the nitrate ions formed within the aerobic zone are denitrified within the anoxic zone. Finally, an oxygen-deficient zone, wherein the mixed liquor is deficient in both dissolved oxygen and NO.sub.3.sup.- and NO.sub.2.sup.- anions and is ready for luxury uptake of oxygen within the pump/aerator, is dependably provided at the end of the anoxic zone.

Abstract: A dual baffle pump/aerator assembly comprising a concave intake baffle which is disposed upon the floor of an endless channel of an oxidation ditch to intercept the flow of mixed liquor within the channel. A horizontal barrier having aeration means associated therewith is disposed above and attached to the intake baffle. A concave discharge baffle is disposed above and attached to the horizontal barrier.

Abstract: A mixing-control apparatus for continuously moving mixed liquor having translational-flow momentum within an endless channel of a closed-circuit oxidation ditch, conserves at least of the portion of the momentum by enabling induced flow of the mixed liquor through adjustable openings in the barrier.

Abstract: In aerobic wastewater treatment systems, such as sewage treatment, liquid in a channel spanned by a liquid-tight barrier is moved past the barrier by a liquid-gas contact pump, thus dissolving a gas in the liquid and creating a differential head that provides flow energy for moving the liquid in plug-type flow through the channel, which is preferably a continuous-flow pipeline or a circuit-flow oxidation ditch, without energy-wasteful vertical circulation. The barrier further provides a structure for mounting submerged static aerators or a draft tube, in combination with a surface aerator, such as a submerged turbine or surface-disposed impeller aerator, as the liquid-gas contact pump. The barrier is disposed at sufficient depth, when combined with static aerators or when telescopically attached to the draft tube of a floating surface aerator, to enable the liquid level to be selectively varied so that flow equalization to an oxidation ditch and wastewater storage therewithin are provided.

Abstract: This flow-control apparatus for an oxidation ditch comprises a barrier which divides a channel of an oxidation ditch into an intake channel and a discharge channel, at least one submerged turbine which pumps mixed liquor from the intake channel, and at least one discharge duct which connects each turbine to the discharge channel and passes beneath the barrier. Compressed air is supplied to each turbine and/or to each discharge duct. Activated sludge is fed to the anoxic portion of the ditch and/or to each turbine which provides complete mix and propels the mixed liquor in plug-type flow through the channels of the oxidation ditch. By selectively and independently controlling turbine speed and amount and/or feed location of compressed air, the timed aerobic/anoxic ratio for the ditch can be controlled in accordance with independent parameters, such as seasonal temperatures.

Abstract: A barriered circulator/aerator in the endless channel of a barrier oxidation ditch provides a directly pumped flow of mixed liquor into a central liquor inlet zone and an energy-release induced flow of mixed liquor into a surrounding liquor inlet zone at the inlet of a deep oxygen contact duct which passes beneath the barrier to the discharge channel on the downstream side thereof. It further provides mixing of diffused air with the directly pumped flow and/or the induced flow and then moving the combined air-liquor flows into the deepest portion of the contact duct where point-source pressurized aeration of both flows occurs. Eddy jet diffusers are preferably used for aerating the induced flow. Oxygen transfer efficiencies are obtained that are 1.6-2.2 times as great per brake horsepower per hour as that attainable by 100% pumping of the mixed liquor in a total barrier oxidation ditch, as disclosed in U.S. Pat. No. 4,260,278.

Abstract: Methods are provided for converting both plug flow and complete mix basins of the prior art into barrier oxidation ditches. Circulator/aerators are described that can be prefabricated and dropped onto the floor of an existing basin so that, in combination with at least one partition, if needed, an endless channel is created with minimum disruption of the activated sludge process.

Abstract: Methods are provided for converting both plug flow and complete mix basins of the prior art into barrier oxidation ditches. Circulator/aerators are described that can be prefabricated and dropped onto the floor of an existing basin so that, in combination with at least one partition, if needed, an endless channel is created with minimum disruption of the activated sludge process.

Abstract: Dual baffle aerators 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) can also be combined with dual-baffle aerators.An adjustably apertured barriered pump assembly is opened sufficiently to conserve momentum in the translationally flowing liquor while preventing back-mixing of aerated liquor.Processes for providing point-source or multi-source aeration, by using two or more barriered pump assemblies, can be provided at one barrier and the advantages of point-source homogeneous aeration can be provided at another barrier, at least one barrier being adjustably apertured.