Abstract: Method for treating iron-contaminated water using a treatment approach identified herein as the Activated Iron Solids (AIS) Process. The AIS process is capable of oxidizing and removing iron as iron oxides from iron-contaminated waters producing a clean effluent. The AIS process is performed in a single or multiple tank system in which high concentrations of AIS are suspended through mechanical mixing to maintain a catalytic surface chemistry environment that increases iron removal thousands times faster than would naturally occur and hundreds times faster than existing arts (e.g., aerobic pond passive treatment). The AIS process can utilize inexpensive alkaline material (such as, pulverized limestone) where initial mine drainage alkalinity (mg/L as CaCO3) to ferrous iron (mg/L) ratio is less than approximately 1.7.

Abstract: Systems and methods for treating wastewater including a dissolved air flotation operation performed upon a portion of a mixed liquor output from a contact tank prior to the mixed liquor entering a biological treatment tank.

Abstract: Fluorescence in situ hybridizations were used to identify and determine the abundance of nitrifying bacteria and Anammox bacteria (recycling bacteria) in freshly settled sludge of biological nutrient removal (BNR) secondary clarifiers. An uneven distribution was observed for recycling bacteria in two BNR systems. Settling patterns suggest microcolony formation processes are sensitive to the internal recycle rate, which allow for rapid recycling bacteria microcolony growth by increasing circulation of flocs through the aeration and anoxic basins. Sludge containing high levels of recycling bacteria are selectively collected and separated from the remaining sludge, uncoupling the solids retention time (SRT) of the recycling bacteria from the wasting bacteria. Elevated recycling bacteria SRTs increase concentrations of nitrifying bacteria in the aeration basin and Anammox bacteria in the anoxic basin, improving nitrification and anaerobic ammonium oxidation.

Abstract: The wastewater treatment method includes, when raw water is subjected to an activated sludge treatment, performing a first sludge returning step: a step of returning sludge, which was previously aerated and stirred in a first excess sludge tank or sludge retention tank equipped with an aerator and a stirrer, to an treatment tank, a sequencing batch reactor or an anaerobic tank; an optional step of returning sludge, which was previously aerated and stirred in a second excess sludge tank or thickened sludge retention tank equipped with an aerator and a stirrer, to a treatment tank, a sequencing batch reactor or an anaerobic tank; and maintaining genus Bacillus bacteria in the treatment tank, the sequencing batch reactor or the anaerobic tank, to which the sludge has been returned, at 2.0×105 to 22.5×105 cfu/mL.

Abstract: A fine bubble generating apparatus that efficiently generates fine bubbles on the nanometer level. A cylindrical member has a cylindrical inner peripheral surface, a first end wall member closing one end of the cylindrical member, and a second end wall member closing the other end of the cylindrical member. The cylindrical member and the first and second end wall members define a fluid swirling chamber. The cylindrical member has a fluid inlet hole at a position close to the second end wall member to supply a gas-liquid mixed fluid in the tangential direction of the peripheral surface of the fluid swirling chamber. The second end wall member has a fluid outlet hole extending therethrough along the center axis of the inner peripheral surface of the fluid swirling chamber. The gas-liquid mixed fluid is introduced into the fluid swirling chamber at a position close to the second end wall member.

Abstract: A modularizable system for residential water treatment having a low energy requirement to process water for reuse at the residence which results in a reduction in the amount of fossil fuels required to power large water processing stations and transfer water from water plants to individual residences is disclosed. The system increases availability of water at the residential level in areas where water is a limited or limiting resource (e.g., in arid climates). Furthermore, the amount of water a residence uses in a given cycle is more efficient.

Abstract: A wastewater treatment system having a tank, a rotatable surface aerator and an elongate draft tube is presented. The elongate draft tube is at least partially submerged beneath the liquid and is rotated about its longitudinal axis for orbitally moving the liquid through the tank in a fixed direction. The rotatable surface aerator is coupled to the proximal end of the draft tube and is at least partially immersible into the liquid. The system further can provide an anoxic zone. A process for treating wastewater is also provided.

Abstract: A method for treating waste-activated sludge comprises adding (1) a pozzolanic material to waste-activated sludge to form a mixture. The mixture is homogenized and aerated (2). The pozzolanic material reacts with the waste-activated sludge. The mixture is allowed to settle (3). A portion of the mixture is recirculated (4) from a downstream location to an upstream location. The recycled mixture includes pozzolanic material. Some embodiments provide advantages over existing wastewater treatment methods which may include: reduction or elimination of unpleasant odours, reduction of overall costs, conversion of waste into useful products, and/or reduction or elimination of discharged bacteria or other undesirable materials.

Abstract: A method and system for purifying production water obtained from oil and gas operations so that the purified water need not be disposed of by forced injection back into the geological formation but can be put to a beneficial use such as agriculture, irrigation, industrial or municipal or potable applications. The production water is treated in a ceramic microfilter after it has been pretreated (preferably by aeration and with a walnut shell filter) to remove volatile hydrocarbons and heavier oils, such as paraffins and asphaltenes, that could foul the ceramic filter. The permeate from the ceramic microfiltration can then be treated with activated charcoal or otherwise treated to meet the specific requirements for the intended beneficial use.

Abstract: An aspirator includes a plurality aspirator tubes, each preferably extending at approximately 70 degrees from a central axis and including a fin extending a limited distance below the aspirator tube outlet. The design improves mixing and gas contact, yet has reduced power requirements, by using a plurality of debris-shedding, finned aspirator tubes to inject approximately 35% more air than the best prior art designs at the same rotational speed. Further, the aspirator of the present invention improves motor life by reducing the average current draw on the motor. The aspirator is useful in many applications, including sewage and wastewater treatment, oxygenation, fermentation, aeration, hydrogenation, oxidation, and oil-sand separation.

Abstract: The present invention relates to a process for treating wastewater. The process includes the steps of (a) mixing different constituents of said wastewater inside a container, (b) withdrawing said wastewater from container, (c) feeding said wastewater to a bioreactor, (d) contacting said wastewater with an isolated microorganism or an isolated microorganism consortium, (e) aerating a suspension of said wastewater with said isolated microorganism or said isolated microorganism consortium, (f) withdrawing said suspension of said wastewater with said isolated microorganism or said isolated microorganism consortium from said bioreactor, (g) filtering receiving flow from step (f) to separate a concentrate stream from a permeate stream, (h) returning said concentrate stream to said bioreactor and (i) removing permeate stream.

Abstract: A method for removing contaminant from feedwater by forming a dispersion comprising bubbles of a treatment gas in a continuous phase comprising feedwater, wherein the bubbles have a mean diameter of less than about 5 ?m and wherein the treatment gas is selected from the group consisting of air, oxygen, and chlorine. A method for removing contaminants from a feedwater by subjecting a fluid mixture comprising feedwater and a treatment gas to a shear rate greater than 20,000 s?1 in a high shear device to produce a dispersion of treatment gas in a continuous phase of the feedwater. A system for treating feedwater to remove contaminants therefrom is also presented, the system comprising at least one high shear mixing device comprising at least one generator comprising a rotor and a stator separated by a shear gap; and a pump configured for delivering feedwater and treatment gas to the high shear mixing device.

Abstract: Waste treatment systems and methods of using them to treat septage, domestic sludge or both are disclosed. Certain examples provided herein relate to waste treatment systems that include a plurality of stages, such as, for example, a plurality of ecosystems, configured to treat domestic sludge, septage or both.

Abstract: An activated sludge wastewater treatment method is provided. The disclosed method includes: receiving a stream of wastewater into a mixed liquor in an uncovered activated sludge basin; introducing high purity oxygen to the mixed liquor in the activated sludge basin to produce euoxic conditions (i.e. a dissolved oxygen level in the range of between about 5 mg to 15 mg) in the activated sludge basin; passing a portion of the mixed liquor in the activated sludge basin through a clarifier to separate activated sludge and produce an effluent stream and an activated sludge stream; and recycling a portion of the activated sludge stream to the activated sludge basin to produce a mixed liquor having a solids loading of between about 3000 mg and about 10000 mg of suspended solids per liter of mixed liquor and a solids retention time of between about 7 days and 40 days.

Abstract: The present invention is directed to a substantially odorless biologically mediated treatment process for solid and liquid organic wastes. The present invention also provides for a novel nutrient rich humus material produced from the biologically mediated treatment process. The bioconversion process of the present invention results from low electron acceptor concentrations and high quantities of microorganisms in a diverse microbial community.

Abstract: A trumpet-shaped slinger atomizes or aerosolizes liquid by lifting liquid from adjacent the surface of the liquid using helically oriented fins rotated by spinning the slinger on a shaft. The lifted liquid is centrifugally forced over an increasing surface area and ejected from an upper edge as droplets. When used in wastewater aeration, radial fan blades on top of the slinger break up foam and increase air circulation while the increased surface area of the droplets increases diffusion of dissolved gasses from the wastewater.

Abstract: A method for removing contaminant from feedwater by forming a dispersion comprising bubbles of a treatment gas in a continuous phase comprising feedwater, wherein the bubbles have a mean diameter of less than about 5 ?m and wherein the treatment gas is selected from air, oxygen, and chlorine. A method for removing contaminants from a feedwater by subjecting a fluid mixture comprising feedwater and a treatment gas to a shear rate greater than 20,000 s?1 in a high shear device to produce a dispersion of treatment gas in a continuous phase of the feedwater. A system for treating feedwater to remove contaminants therefrom is also presented, the system comprising at least one high shear mixing device comprising at least one generator comprising a rotor and a stator separated by a shear gap; and a pump configured for delivering feedwater and treatment gas to the high shear mixing device.

Abstract: The invention relates to a method for purifying wastewaters, particularly wastewaters produced in the paper industry, involving the following steps: a) aerobic clarification of the wastewater using activated sludge in an activation stage; b) carrying out, in a secondary settling tank, a subsequent clarification of a portion of the wastewater/activated sludge mixture leaving the activation stage; c) desiccating, in a desiccation unit, another portion of the wastewater/activated sludge mixture leaving the activation stage; d) returning at least a portion of the activated sludge removed in steps b) and c) into the activated sludge tank.

Abstract: The present invention relates to a method for the aerobic digestion of a fluid waste material, notably an aqueous sewage, in which at least part of the waste material and/or of the digestion mixture is comminuted to reduce the median particle size of biomass and other solid particles in the digestion mixture to less than 10 micrometres, for example using destructive cavitation with a pressure drop of from 2 to 7.5 Bar. The comminution produces particles which are preferentially ingested by predator organisms in the digestion stage so that they graze on the bacteria and biomass particles and thus reduce the amount of biomass and suspended solids produced in the digestion stage. The invention also relates to apparatus for use in the method of the invention.

Abstract: According to this wastewater treatment apparatus, wastewater can be treated by novel action by a foaming tank 7 in comparison with a treatment method solely using a biological treatment tank 1 constituting an aeration tank. That is, wastewater can be treated by action achieved by combining (1) action solely of a biological treatment tank 1 and (2) action of a foaming tank 7. Specific action in this foaming tank 7 includes supply of dissolved oxygen to wastewater and oxidation by bubbled air (micro air) under a favorable condition with a shallow water depth. According to this wastewater treatment apparatus, energy to be consumed can be saved and toxic chemical substances such as dimethylformamide as a toxic chemical substance can be completely decomposed by unlimited microorganisms.

Abstract: A method and apparatus for retrofitting existing waste water treatment facilities having at least one existing basin including installing generally vertical partitions at spaced locations in the at least one existing basin in order to divide the at least one existing basin into a plurality of treatment stage regions, installing at least one air lift in each of the plurality of treatment stage regions, loading each treatment stage regions with a quantity of floatable porous particles, supplying waste water to at least one of the plurality of treatment stage regions and allowing the waste water, but generally not the particles, to flow from at least one of the plurality of treatment stage regions to at least another of the plurality of treatment stage regions and operating the at least one air lift in each of the plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with the floatable porous particles.

Abstract: Method for purifying waste water, whereby the waste water is subjected to a biological treatment producing sludge, part of this sludge being recycled towards the biological treatment while being subjected to ozonation combined with mechanical stirring. A mechanical stirring energy is brought in to attack the walls of the microorganisms.

Abstract: A process for biological purification of waste water by the activated sludge method wherein the waste water is continuously passed through one or more treatment zones and a clarification zone, wherein the waste water treated in the last treatment zone at the outlet from the zone under suitable control of aeration and stirring is continuously divided into a predominantly aqueous fraction and a sludge-containing fraction, and wherein a portion of the sludge fraction is recirculated and mixed with non-treated waste water, of which the former is subjected to clarification, and the latter is recirculated to the same or a preceding treatment zone.

Abstract: The aspirator is utilized to introduce air, oxygen, or other gases into a liquid. The advantages of the present design include the ability to inject approximately 30% more air than a conventional current design at 50% of the rotational speed. This reduces the power requirements. Additionally, the 45 degree angle of the aspirator tubes helps to shed debris that might otherwise collect on the aspirator. The aspirator design includes a fin along the aspirator tube, which is formed at a 45 degree angle relative to the aspirator shaft. Superior mixing is provided by the larger profile of the aspirator. The fins along the bottom of the aspirator tubes help to create larger voids in the liquid. This increases the aspirator's capacity to inject air, while minimizing the material requirements of the part.

Abstract: A biochemical oxidation system and process is disclosed for the removal of insoluble sulfides from metal ores. A liquid mixture of an ore slurry and of a liquid biochemical oxidation medium is flowed through a plurality of covered overflow tanks connected in series. The liquid mixture is continuously aerated in an aeration chamber formed in the tanks with a mixture of a purified oxygen gas and a purified carbon dioxide gas as introduced into the aeration chamber. A substantially sulfide-free liquid mixture is discharged from a last tank into a clarifier in which at least a portion of the biochemical oxidation medium is separated from the liquid mixture for recirculation into the tanks.

Abstract: The invention is a biological process for purifying waste water in order to produce an effluent with a low content of carbon and of oxygenated nitrogen compounds. The process includes an initial step of mixing the waste water in a biological reactor with activated sludge to denitrify the resulting mixture. Then, air is introduced into the mixture to form an anoxic sludge thereby directly oxidizing carbon present in the anoxic sludge and removing carbon therefrom, simultaneous with the denitrification. The anoxic sludge is clarified to separate it from a denitrified intermediate effluent. The clarified anoxic sludge is recycled to the biological reactor.

Abstract: Liquid in which oxygen-containing gas is to be dissolved is pumped through a main and distributed into faster-moving subsidiary streams. Each subsidiary stream passes through a turbulence-inducing means and air or oxygen is introduced into the turbulent region of alternate streams. The relative proportions of air to oxygen introduction are varied so as economically and efficiently to oxygenate the liquid. The gas-containing liquid passes through nozzles back into the volume of the liquid at sufficient velocity to cause further turbulence, making gas bubbles shear into smaller bubbles and also agitating the body of liquid.

Abstract: Methods and apparatus for treating waste streams utilize controlled introduction of microscopic gaseous bubbles to create, in a single vessel, as many as three separate biological environments in discrete, stratified zones. In preferred embodiments, bubbles of air are introduced at the bottom of the vessel, creating an aerobic zone in this vicinity. Depletion of oxygen by microorganisms resident in this layer creates an anoxic zone that drifts upward, establishing itself above the aerobic layer. The two layers remain segregated due to the intolerance of aerobic microorganisms for the overlying anoxic environment, the sharpness of the interface depending on the degree of intolerance.

Abstract: A wastewater treatment plant for removal of organic matter, suspended solids and other pollutants comprising a pre-treatment chamber, a biofilm-aeration chamber and a settling chamber. Biofilm grows on biofilm support structure which is stationary and submerged in the mixed liquor of the biofilm aeration chamber. The combination of submerged or surface aeration and suspended solids particle size reduction occurs thereby creating a sufficient fluid flow within the biofilm aeration chamber. This combination of sufficient fluid flow, and reduced size suspended organic particles results in the efficient digestion of organic matter and pollutants by the biofilm growing on the biofilm support structure submerged in the biofilm aeration chamber. This results in a vastly more effective digestive process than conventional processes producing no sludge. Further, resulting treated effluent has a high dissolved oxygen content and low BOD and SS.

Abstract: A method for treating liquid waste water sludge after its generation and separation from the waste liquid involves forcibly impacting sludge particles and microbial cells against a contact surface to thereby fragment the particles into smaller-sized particles and break apart the organic cells. As a result of such a fragmentation process, water located in the pores of the sludge particles is released, thereby enhancing a subsequent dewatering process performed on the sludge. The destruction of the cells permits a subsequent solids digestion process to work more efficiently, while also permitting a more complete conversion to dissolved sugars, proteins and carbon dioxide.

Abstract: A method and the apparatus for the dissolving gas in liquid, in particular, dissolving oxygen and elimination of variable flow rates in wastewater collection and transmission systems that provides the means to stop the generation of toxic chemicals, allows existing pipeline capacities to be doubled, provides twice the capacity from existing wastewater treatment plants and improves the quality of the discharge of the wastewater treatment plant.

Abstract: A waste liquid treatment system (10) includes an aeration chamber (10A) and a settling chamber (13). An aerator (11) is disposed within the aeration chamber (10A). A conduit (12) delivers liquid from the aeration chamber (10A) to the settling chamber (13). A gas pocket (P) is provided in the aerating chamber (10A), with at least a portion of the gas pocket (P) being situated beneath the liquid level line (L.sub.13) of the settling chamber (13). Conduits (18 and 19) are provided for delivering liquid from the settling chamber (13) to the aeration chamber (10A). The conduits (18 and 19) have respective outlets (24, 26) which empty into the gas pocket (P) at an elevation below the settling chamber liquid level line (L.sub.13). In one embodiment, a gas pocket (P) is provided in the interior of a tubular component (23) of the aerator (11). In another embodiment, a gas pocket (P') is provided beneath a concave hood (32) which traps gas bubbles (30) introduced into an aeration chamber (110A).

Abstract: Apparatus and system 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 centrifugal pump as back pressure is provided in the collector. The collector is mismatched relative to the impeller to increase the retention and mixing time of the air and waste in the collector. The collector within the impeller forms a pump designed to operate close to its shut-off condition for increased retention time in the collector.

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: The invention relates to an installation for aerobic biological purification of pollutant-containing water, which installation consists of an axial-flow submerged reactor and a sedimentation tank for separation of the biosludge from the purified water. The reactor is a pipe containing a two-stage activated-sludge chamber, which pipe contains (a) a first activated-sludge stage in which a driving-jet nozzle is disposed at the downstream end for the dispersion of the air and the microorganisms in the waste water to be purified, and (b) a second activated-sludge stage in which internals are disposed for homogeneous dispersion of the gas bubbles and the microorganisms as well as for immobilization thereof.

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 two-stage, batch process for purifying wastewater containing organic and adsorbable pollutants includes the steps of introducing a predetermined quantity of the wastewater into an aeration and settling zone of a primary treatment zone and aerating therein in the presence of a powered absorbent, such as activated carbon, and biologically active solids, terminating aeration and retaining the thus-treated wastewater in the aeration and settling zone a sufficient time for a substantial portion of the suspended solids to settle by gravity. A predetermined amount of the partialy-treated wastewater is withdrawn from the aeration and settling zone and introduced into a contact zone wherein it is agitated, preferably by aeration, in the presence of a powered adsorbent, agitation is terminated and the solids are allowed to settle by gravity. After completion of settling, clarified, substantially solids-free water is withdrawn from the contact zone.

Abstract: A two-stage process for purifying wastewater containing organic and adsorbable pollutants includes the steps of first aerating the wastewater in the presence of a powdered adsorbent, such as activated carbon, and biologically active solids in the aeration zone of a primary treatment zone which also includes a quiescent zone. The thus-treated water passes from the aeration zone to the quiescent zone where it is retained a sufficient time for a substantial portion of the suspended solids to settle by gravity. The partially-treated wastewater overflowing from the quiescent zone is introduced into one or more contact zones wherein it is agitated, preferably by aeration, in the presence of a powdered adsorbent, agitation is terminated and the solids are allowed to settle by gravity and, after completion of settling, clarified, substantially solids-free water is withdrawn from each contact zone.

Abstract: In the particular embodiments of the waste water treatment system described in the specification, a waste water treatment basin has spaced-apart, moving aerator chains extending across the basin in a direction transverse to the flow of waste water through the basin. When an aerator chain is provided with air, bottom aerators suspended from the chain adjacent to the bottom of the basin move with respect to the basin to mix sludge collected on the basin with the waste water and to supply air to the waste water. A control system supplies air selectively to the aerator chains to provide zones of full aeration and intermediate zones with little or no aeration and the selection of the aerator chains is changed periodically in a progressive manner along the basin so that the zones move progressively through the basin.

Abstract: A method of removing nitrogen and phosphorus from waste water by using an activated sludge including aerobic bacteria is disclosed. The waste water is fed continuously and gradually into a treatment basin in which the sludge is contained so that a mixed liquor consisting of the waste water and the sludge is formed therein. A cycle consisting of an agitating step and an aerating step is repeated at least two times and each cycle is finished within two hours, with the ratio of the agitating time to the aerating time being between one to one and to one. In the agitating step, the mixed liquor presents an anoxic condition and a succeeding anaerobic condition. Denitrification occurs in the anoxic condition and the aerobic bacteria release phosphorus in the anaerobic condition. During the aerating step, nitrification is caused while the bacteria excessively ingest phosphorus from the mixed liquor.

Abstract: A method and apparatus for biological aerobic treatment of wastewater wherein oxygen is induced into a mixed liquor flow path and a method and apparatus for separating the liquid withdrawn from the mixed liquor flow path into a clear liquid stream and a flock laden stream. A streaming specific gravity separator of unique construction and operation separates the mixed liquor into a clear liquid stream and a flock laden stream, withdrawing the clear liquid stream from the system and directing the flock laden stream back into the mixed liquor flow path. The separator functions within the system to be self-controlling for load increases or decreases.In accordance with preferred embodiments of the system, the separator may be positioned inside or outside of an oxidation ditch. The separator may also be utilized in combination with an aeration basin.

Abstract: Method for cleaning waste water, wherein the waste water (19) and oxygen gas (31) are flowing in opposite directions through a cylindrical multireactor (20) having a central rotatable pipe (24), the multireactor comprising a number of bioreactors and at least one separation chamber (75). The average pressure difference between two successive bioreactors is at most seven meter water column. The bioreactors are separated from each other by stationary walls (40, 41, 48, 55, 60), and each bioreactor has its own mixing device (50) for mixing waste water and oxygen gas.

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: An apparatus and a method for biological treatment of waste waters achieving biological oxidation of organic matter, biological nitrification and denitrification of nitrogenous compounds and biological removal of phosphorus and clarification of the treated waste water in a single reaction tank in a single suspended growth sludge system without the use of traditional compressors, mixers, recirculation pumps, piping and valving and without the use of the traditional clarifier.

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: A waste water treatment plant providing biological oxidation, biological nitrification and denitrification and biological removal of phosphorus and clarification of the treated waste water in a single reaction tank in a single suspended growth sludge system without the use of the traditional compressors, surface aerators, mixers, recirculation pumps, sludge scrapers, sludge return pumps, piping and valving.

Abstract: Means and method for controlling submergence of surface aeration apparatus in enclosed covered aeration zones wherein liquid level is dependent on pressure of the overlying gas volume. Power consumption of the surface aeration device is sensed by a transducer coupled in controlling relationship with means for regulating the flow of aeration gas passed through the aeration zone. Changes in power consumption caused by liquid level variation are employed to adjust the flow rate of gas passed through the aeration zone, thereby adjusting the gas pressure in the zone to maintain liquid level therein relatively constant.

Abstract: A process and apparatus for the purification of effluent waters containing organic pollutants by a rapid biological oxidation (activated sludge) process characterized in that the liquid to be purified is introduced into a tank containing a liquid having a high biomass concentration. Liquid is drawn from the tank and reintroduced through an aerating device in such a way as to produce rotation of the liquid in the tank to the extent that a vortex is produced on the surface. A part of the liquid taken from the tank is strayed on to the vortex and a proportion passed to a mechanical separating means that separates sludge from the liquid and a proportion of the separated sludge is reintroduced directly in to the tank. The liquid from which the sludge has been removed constitutes the purified effluent.

Abstract: Method for purifying waste water, whereby the waste water is subjected to a biological treatment producing sludge, part of this sludge being recycled towards the biological treatment while being subjected to ozonation combined with mechanical stirring. A mechanical stirring energy is brought in to attack the walls of the microorganisms.