Abstract: A plasma-generating apparatus includes a first electrode of which at least a part is positioned within a treatment vessel that is to contain liquid, a second electrode of which at least a part is positioned within the treatment vessel, a bubble-generating part which generate a bubble when the liquid is contained in the treatment vessel, such that a surface where conductor is exposed, of a surface of the first electrode which surface is positioned within the treatment vessel, is positioned within the bubble, a gas-supplying apparatus, a power supply for applying voltage between the first electrode and the second electrode.

Abstract: A method for removing a target compound from a liquid can include arranging two active surfaces so as to be separated by a distance. The active surfaces can be placed within a flow of the liquid and can be capable of supporting an electrical charge, biological growth, and/or enzymes and proteins. The method can further include developing a population of microorganisms concentrated on the active surfaces where the population of microorganisms is configured to or capable of transformation of the target compounds. The method can further include developing enzymes or proteins concentrated on the active surfaces where the enzymes or proteins are configured to or capable of transformation of the target compounds. The method can further include applying a potential difference between the two active surfaces. The microorganisms and the potential difference can be sufficient in combination and/or with specific nutrients to remove the target compound from the liquid and maintain the population of microorganisms.

Abstract: A fluid purifying apparatus that purifies fluid containing organic matter has a reactor including a first transfer part that receives the fluid from outside and transfers the fluid in a vertical direction from an upper side to a lower side while heating and pressurizing the fluid and mixing the fluid with an oxidant, a second transfer part that receives the fluid that has passed through the first transfer part and transfers the fluid in the vertical direction from the lower side to the upper side, and a partition member that partitions an upper part of the reactor into the first transfer part and the second transfer part, and a solid storage part that communicates with the first transfer part and the second transfer part below the partition member and receives solid matter contained in the fluid that settles while the fluid is transferred.

Abstract: The present invention describes an apparatus and method for creating dense nano-multi molecular packing of gaseous molecules concentrated in liquid solutions and the ionization of the resultant dense gaseous nano-multi-molecular molecules forming a concentration of free-radicals saturating liquid solutions without cavitation of nuclei and without bubbles for the dissolution, destruction, disinfection and remediation of biological, chemical and electrochemical threats and contaminants.

Abstract: Systems and methods for aerobically processing waste, in which an aerobic bioreactor is in selective fluid communication with a source of oxygen-rich liquid medium. The aerobic bioreactor is configured for aerobically processing waste via bacteria fixed on media to provide processed effluent from the waste. The source of oxygen-rich liquid medium is different from the aerobic bioreactor.

Abstract: Volatile organic compounds (VOCs), such as benzene, toluene, ethylbenzene, xylene and methanol may be removed from wastewater obtained from oil or gas exploration or production operations by way of a bioreactor. The bioreactor may employ anaerobic microorganisms that metabolize various VOCs. In some embodiments, such a bioreactor may be configured to selectively change the temperature of the conditions of wastewater placed in the bioreactor, or of wastewater re-circulated through the bioreactor. A centralized valving or control station may optionally control heating or other conditioning elements for both feed and re-circulation systems.

Abstract: A biofilm carrier screen is adapted for use with a moving bed bioreactor (MBBR). The screen has a screening body connected to an effluent pipe. The effluent pipe optionally has two parts separated by a union, preferably a pitless adapter. The screening body can be lifted from a bioreactor tank for maintenance after disconnecting the union. The screening body may have an aerator to provide bubbles to disperse biofilm carriers from the screening body. The screening bod may extend downwards from a mount near the top of the tank. In the case of an anaerobic MBBR, the screening body may extend downwards from a service box through a cover over the tank.

Abstract: In a waste treatment system and process, relatively low and high solids concentration streams are treated in generally parallel anaerobic reactors. The reactors may share a common wall or gas collecting cover. The reactors may also share a common downstream aerobic treatment unit. Solids produced during downstream treatment of effluent from one or both anaerobic reactors may be returned to the high solids concentration stream. The low solids concentration stream may be treated in an attached growth anaerobic digester.

Abstract: Volatile organic compounds (VOCs), such as BTEX methanol and other non-phase separable hydrocarbons may be removed from wastewater obtained from oil or gas exploration or production operations by way of a bioreactor. The bioreactor may employ anaerobic microorganisms that metabolize various VOCs. In some embodiments, such a bioreactor may be configured to treat process flow rates of thousands of barrels of wastewater per hour. Such a bioreactor may comprise a large vessel at a larger water treatment site.

Abstract: A wastewater treatment system includes wastewater having nitrogen-containing compounds, an anoxic zone having denitrifying bacteria, and an aerobic zone having nitrifying bacteria. The anoxic zone is coupled to the aerobic zone, and wastewater flows from the anoxic to the aerobic zone or vice versa. A fluidized bed heat exchanger configured to accept heat from a heat engine and to transfer the heat from the heat engine to the wastewater is positioned in the aerobic zone or the anoxic zone. The fluidized bed heat exchanger includes particulate media, and fluidization of the particulate media scrubs bacterial growth from portions of the fluidized bed heat exchanger. Treating wastewater can include flowing wastewater having nitrogen-containing compounds into a biological reactor having an anoxic zone and an aerobic zone, and heating the wastewater with heat from a heat engine to facilitate denitrification reactions in the anoxic zone and nitrification reactions in the aerobic zone.

Abstract: The present invention provides, in at least one embodiment, a system and method for producing cleaner water and air without using additional power. The system produces cleaner water by heating the sucked air, which improves the efficiency of the air stripping. The system produces cleaner air by fanning the contaminated air through a thermal oxidizer and/or a carbon filterator. The fanning is powered by a belt pulley powered by the gravitational force from the contaminated water.

Abstract: A ballasted sequencing batch reactor system for treating wastewater including one or more sequencing batch reactors. A weighting agent impregnation subsystem is configured to mix biological flocs and weighting agent to form weighted biological flocs. A weighting agent recovery subsystem is configured to recover weighting agent from the weighted biological flocs and reintroduce the recovered weighting agent to the weighting agent impregnation subsystem.

Abstract: The invention relates to a method for desulphuration of the digestate and biogas in a digester (1) of urban and/or agricultural and/or industrial effluent, by biochemical and/or thermochemical processes, the digester consisting of an enclosure (2) which is closed at the top, in which anaerobic digestion of a mass of products to be treated making up the digestate (4) takes place, the digester comprising at least one loop (10) for external recirculation of the digestate; an oxidant is injected at least at one point (13, 14) of the loop (10), the injection conditions being as follows: the speed of circulation of the digestate in the loop (10) must be high enough to prevent the deposition of sulphur on the walls of the pipes; the contact time between the injected oxidant and the recirculated digestate recirculated from the injection point (13, 14) of the oxidant until the reinjection point (11 b) of the digestate must be long enough for all the oxidant to be dissolved in the liquid phase of the digestate; the amo

Abstract: The invention discloses systems and methods for producing a gas stream containing ozone and a “carrier” or sweep gas that has an oxygen concentration that is below a predetermined percentage for treatment of organic waste feed stocks in an anaerobic digester. In one embodiment, ozone and unreacted oxygen from an ozone generator are delivered to a pressure swing adsorption cycle, wherein the ozone is adsorbed onto a sieve and the excess oxygen is removed from the cycle. The sweep gas, which has a limited oxygen concentration, is then used to desorb the ozone from the pressure swing adsorption cycle and deliver the ozone to an anaerobic digester, where the ozone is used to treat the feed stock.

Abstract: An anaerobic lagoon wastewater treatment system, which includes a plurality of wastewater treatment zones. The treatment zones are either formed by providing a plurality of separate lagoons or by providing one or more partitioning elements within one lagoon. One or more treatment zones may also be provided in the form of a tank. The first wastewater treatment zone in the direction of wastewater flow has a smaller volume than the second wastewater treatment zone. Further, the first wastewater treatment zone achieves a significant reduction in fat, oil and grease removal, as well as in total suspended solids removal, but only a modest reduction in biological oxygen demand. An effluent from the first wastewater treatment zone is mixed with an effluent from the second wastewater treatment zone such that a predetermined ratio of carbon to nitrogen is maintained within the mixture of first and second effluents.

Abstract: A mixer for anaerobic decomposition of sludge in a digester, captures and compresses biogas emitted by the decomposing sludge. The compressed biogas proceeds through supply lines to gas accumulating apparatus mounted in the lower portion of the digester, close to or on the digester floor. Biogas accumulates in the gas accumulating apparatus to emerge as large mixing bubbles from 6 inches to 10 feet in diameter along their largest dimension. The mixing bubbles are large enough to generate a strong mixing current in the sludge that moves sludge as the bubbles rise to the surface. The mixing current mixes the sludge containing dissolved and suspended pollutants to promote the conversion of the pollutants by microorganisms contained in the sludge.

Abstract: Liquid clarifier and method for clarifying liquid, comprising a liquid reactor which comprises an cylindrical tank having an upper vertical section and a lower tapered section, an inner cylinder extending along at least part of the upper section of the tank and an outlet for clarified liquid at the top of the tank, where the liquid clarifier further comprises a gas compressor adapted to inject compressed gas into the lower region of the cylinder and an inlet for an unclear liquid at the upper region of the cylinder, and at least one partition wall inside the cylinder, where the at least one partition wall create flow channels in the lower region of the inner chamber, where the compressed gas is adapted to be injected through gas inlets in flow channel/s in order to create an upward flow in the flow channel/s having gas inlets, which will create a downward flow in the flow channel/s without gas inlets, where the at least one partition wall extends out of the lower region of the cylinder.

Abstract: An anaerobic lagoon wastewater treatment system has a flow-splitter tank for accurately dividing a flow of raw, untreated wastewater. The system is designed as an earthen basin or as a tank and includes at least one partitioning element for providing two connected wastewater treatment zones. The first wastewater treatment zone in the direction of wastewater flow has a larger volume and is more efficient in the removal of biological oxygen demand (BOD) than the second wastewater treatment zone. The flow-splitter tank divides the incoming wastewater flow into two streams, which are conducted to the first and second wastewater treatment zones, respectively. A predetermined ratio of carbon to nitrogen is maintained within an effluent pumped from the second wastewater treatment zone by adjusting the relative amount of raw wastewater added directly to the second wastewater treatment zone.

Abstract: A wastewater treatment apparatus of the present invention is configured to biologically filter wastewater through multimedia by consecutively performing two stages (the first and second stages) for a multimedia biological filtration process. A carbon source and coagulant are respectively injected during the first and second multimedia biological filtration processes. The first stage multimedia biological filtration process is carried out in anoxic conditions and the second stage multimedia biological filtration process is carried out in aerobic conditions. The media for the first and second stage biological filtration processes are arranged in large-middle-middle large-small size. Thus, the present invention can secure excellent treated water while minimizing loss of water-head by maximizing reflux capability of solids.

Abstract: A modular system for reclamation of a fluid includes a cavitation reactor operative to mechanically oxide the fluid and an ion precipitation system that receives the oxidized fluid from the cavitation reactor and thereafter introduces one or more ions at various locations to initiate precipitation of select materials. The system and associated methodology further includes injecting dissolved air and emulsion breaking chemistry into the fluid before cavitation, coalescing emulsified particulates from the fluid and saturating the fluid in an air saturation chamber that is operable to form a microbial filter.

Abstract: A water treatment unit includes a mixing chamber surrounding the upper end of a riser containing an impeller. Water can be moved from a body of water up through the riser, and out through laterally directed openings into the chamber adjacent to an air inlet. The water moving out the laterally directed openings of the stand pipe, mixes with air drawn in through the air inlet to oxygenate the water, and the oxygenated water exits the chamber into the body of water through one or more water outlets in the lower portion of the chamber due to the head developed by the inflow of water into the chamber. The outward flow of water from the chamber can cause a toroidal or other desired flow of water within the body of water surrounding the water treatment apparatus.

Abstract: The invention, belongs to the field of wastewater treatment technology, is a two-phase anaerobic reactor enhanced by addition of zero valent iron (ZVI). In the reactor, 2˜4 ZVI-filling layers are settled in the middle of the anaerobic hydrolysis-acidification tank, the effluent of which is fed into the rear anaerobic methanogenic tank. The degradation of organics is effectively enhanced in the anaerobic hydrolysis-acidification tank with dosing of ZVI, which may produce more acetic acid that is a desired substrate for the subsequent methanogenesis. Meanwhile, the acidic environment of the hydrolysis-acidification tank is helpful for the dissolution of ZVI to maintain its activity. The reactor is reasonably designed with high performance and strong shock resistance in anaerobic treatment of various wastewaters. Tests in lab-scale showed that hydrolysis-acidification and methanogenesis in this combined system were significantly improved compared with a reference reactor without addition of ZVI.

Abstract: A system for enhancing an activated sludge process including at least one biological reactor. A weighting agent impregnation subsystem is coupled to the biological reactor for mixing biological flocs and weighting agent to impregnate the weighting agent into the biological flocs to form weighted biological flocs. A weighting agent recovery subsystem is configured to recover the weighting agent from the weighted biological flocs and reintroducing the recovered weighting agent to the weighting agent impregnation subsystem.

Abstract: The invention relates to bio-electrochemical systems for treating wastewater, and sour gas produced by anaerobic digestion of organic material. The invention further relates to novel anode/cathode pairing schemes, and electric and hydraulic architectures for use in bio-electrochemical systems.

Abstract: A method of cleaning filtration modules for the treatment of raw water, or wastewater, or activated sludge, is provided by circulating particles in untreated water. The deposits located on the filter membrane outer surfaces are removed by the mechanical action of the particles, without significantly damaging the membrane. Initially, untreated water, wastewater, or activated sludge is chemically-mechanically pretreated. Then the untreated water or wastewater polluted with biologically active material is discharged into a membrane bioreactor system having a filtration unit including at least one filtration tank. At least one submerged filtration membrane module is present in the filtration tank. The untreated water or wastewater in this filtration tank is filled with particles and circulates inside the filtration tank. The particles are non-porous, biologically resistant polymer particles.

Abstract: A treatment system for removing a plurality of pollutants from wastewater includes a removal device for removing a plurality of gross solids from the wastewater, an aeration device for reducing a biochemical oxygen demand (BOD) and a chemical oxygen demand (COD) of the wastewater and a bioreactor containing a bacterial biofilm, said bioreactor including a plurality of cells configured for operation on a predetermined drain fill cycle.

Abstract: A method and apparatus for sanitizing a water dispenser that dispenses water for human consumption is disclosed. The dispenser can be in the form of any dispenser that dispenses water for human consumption employing a reservoir that dispenses water through one or more spigots. Water in the reservoir is sanitized with an air/ozone gas mixture that is transmitted to a porous polymeric diffuser having a central bore and a porous wall. The porosity of the porous wall defines bubble size.

Abstract: A wastewater treatment system is provided having a reactor, first and second bio media and an aeration system. The first bio medium is located proximate an inlet end of the reactor and extends vertically between a top water level and the reactor's floor. The second bio medium is located proximate an outlet end of the reactor and extends vertically between a bottom water level and the reactor's floor. The media are adapted for retaining solids within the reactor as clarified water is withdrawn after treatment. The first bio media is further adapted to act as a baffle thereby causing wastewater to flow generally uniformly into a primary reactor zone. The aeration system includes a plurality of diffusers, some of which may be located adjacent or underneath the bio media and are adapted for promoting the shaking the bio media when activated in order dislodge excessive biomass therefrom.

Abstract: The present invention relates to an anaerobic reactor (10) for the treatment of industrial and other wastewaters at psychrophilic temperatures, the reactor comprising a mixing chamber (12) in which is located, during use, a granular sludge fluidised bed, the reactor further comprising a biofilm chamber (16) fed from the mixing chamber and housing a biofilm colonised pumice-based carrier material, and a separation chamber (18) in fluid communication with the biofilm chamber and in which treated effluent and biogas produced within the reactor are separated.

Abstract: A carbon adsorption vessel for use in a CIP (carbon in pulp) or CIL (carbon in leach) process may be constructed. A slurry is obtained having dissolved (leached) precious metals. The slurry is brought into contact with carbon particles and is passed through a retention screen in the vessel. The dissolved precious metals adhere onto the carbon particles. An air lift pump provides the pressure differential necessary to drive the slurry through the retention screen, wherein the carbon particles are retained by the retention screen and the slurry passes through the retention screen. After passing through the retention screen, the slurry is received in to a receiving vessel that may be situated at, below or above the level of source vessel.

Abstract: An apparatus, system, and process for wastewater treatment. The apparatus can include a basin for receiving a liquid to be treated, the liquid having a direction of flow, and a plurality of pendant sheets for supporting the growth of microorganisms, disposed within the basin and in contact with the liquid, wherein the pendant sheets are oriented parallel to the direction of flow of the liquid.

Abstract: A device for purifying water includes: a reactor housing having an inlet opening for supplying polluted water and an outlet opening for draining the purified water from the reactor housing; hydrodynamic cavitation means arranged in the reactor housing for causing cavitation in the polluted water; main light means for irradiating the polluted water with ultraviolet light, wherein the main light means provide a polychromatic and/or monochromatic pulsed ultraviolet light, which is synchronized selectively with the specific cavitation event(s) in the polluted water.

Abstract: A biofilter is provided. The biofilter comprises a housing; an inlet defining an upstream end of the housing; an outlet defining a downstream end of the housing; a chamber comprising an upstream opening and a downstream opening, the chamber configured to contain a filtration medium; and a counter flow generator for generating a counter flow of water in an upstream direction in the chamber. Related methods and systems are also provided.

Abstract: A method of wastewater treatment is described. The method includes: (i) receiving wastewater produced after anaerobic digestion; (ii) performing a first type of treatment on wastewater to produce wastewater having a first property which is capable of changing; (iii) preventing the first property from changing; (iv) performing a second type of treatment on wastewater; and wherein the first property includes at least one property selected from a group consisting of biochemical oxygen demand (“BOD”) level, dissolved oxygen level, solid content and nutrient level.

Abstract: Anaerobic treatment of water is performed under anaerobic conditions with a biofilm formed on a surface of a fluid non-biological carrier in a reaction vessel. Stable high-load treatment is performed by preventing the blockage of the reaction vessel caused by the flotation and adhesion of the non-biological carrier in the reaction vessel and effectively recovering the settleability of the carrier floating owing to adhering air bubbles by simple means. A reaction vessel is charged with a fluid non-biological carrier having a size in the range of 1.0 to 5.0 mm and a settling velocity in the range of 200 to 500 m/h. Part of the carrier that has floated and flowed out of the reaction vessel is fed downward through a pipe having a vertical height of 50 cm or more so as to remove air bubbles adhering to the carrier and is returned to the reaction vessel.

Abstract: An apparatus for water filtration, that includes a macroalgal attachment means defining a first macroalgal attachment surface and a bubbling means including, a housing defining a gas inlet and a set of gas bubble ports, and a coupling means. The coupling means secures the macroalgal attachment means to the bubbling means and aligns the first macroalgal attachment surface with the set of gas bubble ports such that a first portion of the gas bubbles to be produced by the gas bubble ports are directed to travel along the first macroalgal attachment surface in contact with the first macroalgal attachment surface.

Abstract: A wastewater treatment system includes wastewater having nitrogen-containing compounds, an anoxic zone having denitrifying bacteria, and an aerobic zone having nitrifying bacteria. The anoxic zone is coupled to the aerobic zone, and wastewater flows from the anoxic to the aerobic zone or vice versa. A fluidized bed heat exchanger configured to accept heat from a heat engine and to transfer the heat from the heat engine to the wastewater is positioned in the aerobic zone or the anoxic zone. The fluidized bed heat exchanger includes particulate media, and fluidization of the particulate media scrubs bacterial growth from portions of the fluidized bed heat exchanger. Treating wastewater can include flowing wastewater having nitrogen-containing compounds into a biological reactor having an anoxic zone and an aerobic zone, and heating the wastewater with heat from a heat engine to facilitate denitrification reactions in the anoxic zone and nitrification reactions in the aerobic zone.

Abstract: A fluid purification unit includes a case including a hollow and a plurality of openings communicating with the hollow to flow a fluid inside into the hollow and outside from the hollow, the case including combining protrusions formed on a first face and concave portions formed on a second face opposite to the first face, each of the combining protrusions having a first cross sectional area and being regularly arranged in a first direction and at a first interval and each of the concave portions having a second area corresponding to the first cross sectional area and being arranged at a second interval corresponding to the first interval.

Abstract: A biological wastewater treatment system is provided which is adaptable to small, shop fabricated package plants and large, assembled in place plants, and which can be operated as a secondary treatment, activated sludge process, for suspended solids and BOD removal, or a tertiary treatment, activated sludge process, for suspended solids, BOD, nitrogen and phosphorus removal. The system includes a wastewater pump and an air aspirator-mixer to provide aeration, sludge recirculation and waste, and wastewater recirculation for the secondary and tertiary treatment processes. The aeration system with the air aspirator-mixer transfers oxygen to the wastewater, and is located outside aeration tanks. The wastewater pump and air aspirator-mixer system lends itself to continuous and cyclic aeration and oxic and anoxic treatment processes. The multiple use of the wastewater pump for aeration, recirculation and sludge waste minimizes the number of pumping systems required and eliminates air blowers.

Abstract: This invention relates to the field of human waste handling, treatment and disposal in mobile public carriers. In particular the invention is directed to a self- sustained bio-digester for onboard degradation of human waste.

Abstract: A system for enhancing an activated sludge process including at least one biological reactor. A weighting agent impregnation subsystem is coupled to the biological reactor for mixing biological flocs and weighting agent to impregnate the weighting agent into the biological flocs to form weighted biological flocs. A weighting agent recovery subsystem is configured to recover the weighting agent from the weighted biological flocs and reintroducing the recovered weighting agent to the weighting agent impregnation subsystem.

Abstract: A method is for the treatment of ballast water, in which the ballast water is carried into a ballast tank via a down pipe and in which an underpressure created at the upper portion of the down pipe induces the formation of gas bubbles in the ballast water. Before flowing into the down pipe, the ballast water is carried via a throttling device into a closed container at the upper portion of the down pipe, the closed container having a flow area larger than the flow area of the down pipe.

Abstract: An apparatus for a programmable self sanitizing water dispenser apparatus with a digital controller as well as a programmable method for generating ozone for cleaning the reservoir and the water contained within it. The apparatus includes an anti-spill receiver that houses the controller and that can contain a ozone generator.

Abstract: A system for mixing a gas in a fluid including an inlet section in fluid communication with a fluid source and a gas source, a nozzle, and a flow reverser. The inlet section has a throughbore in which the fluid and the gas combine to form a treated fluid. The nozzle receives the treated fluid from the inlet section and accelerates the treated fluid. The flow reverser has an open end in fluid communication with the nozzle and a closed end. The nozzle is oriented relative to the flow reverser to direct the treated fluid toward the closed end of the flow reverser. The flow reverser receives the treated fluid from the nozzle and mixes the treated fluid.

Abstract: In some embodiments, a wastewater treatment system may reduce contaminants in water. A system may include one or more basins which include a substrate that supports a biofilm. The bacteria used to form the biofilm may be selected to maximize the reduction of contaminants in water. Various components of the wastewater treatment system may be optimized to improve the efficiency and energy consumption of the wastewater system.

Abstract: A process for affecting reductive conversion reactions in a reactor using the palladized bacterial cellulose immobilized on a support for reductive conversion reactions in a reactor.

Abstract: An energy conserving wastewater treatment system capable of being fueled by alternate fuel sources comprises a synthesis gas generator that produces synthesis gas from a fuel and an organic waste digester that produces biogas. A combined synthesis gas and biogas storage reservoir that is in communication with both the synthesis gas generator and the organic waste digester. At least one boiler is in communication with the combined synthesis gas and biogas storage reservoir.

Abstract: Constructed wetland wastewater treatment equipment under low temperature for continuous operation which includes: three-section substrates filled in a constructed wetland, ventilation pipes being arranged in the substrates, a height of a bed of the constructed wetland being higher than a height of the substrates; a double wall being filled with an organic substance used as a barrier at periphery of the constructed wetland; a water distributing pipe disposed at a top of the three-section substrates and a water collecting pipe disposed at a bottom of the three-section substrates; and a water inlet pipe connected to an upper portion at one end of the three-section substrates and a water outlet pipe connected to a lower portion at the other end of the three-section substrates, a water outlet of the water outlet pipe being higher than the height of the bed of the constructed wetland.

Abstract: A water treatment apparatus includes a plurality of meshed tubes made of synthetic yarn and provided with cilia; a plurality of tube stack cages containing the meshed tubes; and an aeration diffuser positioned between the tube stack cages and configured to provide air so that to-be-treated influent water moves to the tube stack cages. The hollow interior of the filter media, i.e. meshed tubes, enables water to move in any direction, and the high porosity maximizes the area for filtering of suspended solids and attachment of microorganisms. The resulting efficiency of removal of suspended solids and soluble organic material is far greater than conventional methods. Arrangement of diffusers in the middle of the reaction tank and between the tube stack cages and aeration by them result in perfect mixing in the reaction tank. The load of suspended solids and soluble organic materials is evenly distributed over the entire filer media.

Abstract: Aqueous liquid having an oxygen demand flows into a treatment vessel where it is treated by suspended aerobic bacterial solids in the presence of dissolved oxygen. A pressurised flow of the treated liquid passes to a clarifying membrane separator effective to separate the flow into a discharge stream of clear liquid and a pressurised recycle stream concentrated in the aerobic bacterial solids. A first oxic gas is employed to scour the membranes and is conveyed away from the membrane separator in the pressurised recycle stream. The pressurised recycle stream is returned to under the surface of the liquid in the treatment vessel. A second oxic gas is introduced either into the pressurised recycle stream or into a further pressurised stream of aqueous liquid flowing into the same volume. The rate of introduction of the oxic gases is controlled with reference to the pH and dissolved oxygen concentration of the liquid in the vessel.