Abstract: The invention provides a system for treatment of wastewater. A pumping system pumps wastewater from a source basin to a recipient basin, while a conduit allows gravitational flow of water from a source basin to a recipient basin when the pumping system is inactive. A controller activates the pumping system to pump wastewater from the source basin to a recipient basin when a wastewater level in the source basin is at a first predetermined height or when a rate of gravitational flow wastewater from the source basin to the recipient basin is below a first predetermined flow rate. The controller also turns off the pumping system when the water level in the source basin is at a source basin minimal level and the water level in the recipient basin is at a recipient basin maximal level. The invention also provides a method for operating a wastewater treatment of the invention, and a pumping system for use in the system of the invention.

Abstract: Introducing a high surface area media into a sewage treatment process to improve and increase capacity of a given process. The high surface area media can be dispersed at strategic locations in a new or existing attached growth wastewater treatment plant so as to provide additional sites for biological growth and improved wastewater renovation.

Abstract: A process and system for treating wastewater is described. The invention degrades sludge produced by treatment of the wastewater to reduce or eliminate the need for sludge dewatering and disposal. The invention also reduces the amount of nutrient additives required to sustain the aerobic wastewater treatment process. In one embodiment the invention includes the steps of (a) providing an aerobic treatment system receiving a supply of the wastewater; (b) treating a supply of the sludge to rupture microbial cells present therein to produce treated sludge having an increased liquid:solid ratio and an increased degradation potential in comparison to untreated sludge; (c) conveying a supply of the treated sludge to the aerobic treatment system; and (d) substantially degrading the supply of treated sludge in the aerobic treatment system. The treated sludge may optionally be subjected to anaerobic digestion prior to delivery to the aerobic treatment system.

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 wastewater treatment facility with a rotating biological contactor (“RBC”) system. The RBC sits in a tank that receives wastewater to be purified. The tank supports a rotatable shaft. One or more stages of rotating disk assembles progressively purify incoming wastewater. Each stage is oriented transversely to the shaft and has a plurality of disk assemblies. Each disk assembly has a number of disks. Each of the disks comprises multiple concentric arcuate segments. The segments are provided with two generally radially extending edges, two circumferential edges that extend between the two radially extending legs, and a front face and a back face. Posts extend from the front and back faces of the disks for stirring wastewater and for offering a site for adherence of biomass suspended in the wastewater. Connecting members interconnect adjacent disks and optionally define a flow channel therebetween.

Abstract: A method for treating wastewater comprises biologically treating the wastewater in a fixed-biomass biological reactor and then treating the wastewater in a ballasted flocculation system. The ballasted flocculation system produces a clarified effluent and sludge containing inert granular material having biomass accumulated thereon and suspended solids. The inert granular material having biomass accumulated thereon is separated from the suspended solids and then cleaned with a cleaning solution. After separating the biomass from the cleaned inert granular material, the cleaned inert granular material is recycled for use in the ballasted flocculation system.

Abstract: The present invention provides an apparatus and method for biologically treating fluids, in particular municipal or industrial wastewater or the like, the apparatus comprising a pair of reservoirs each containing growth medium having a biofilm thereon, the apparatus being arranged to pump the wastewater from one reservoir to another such as to alternatively expose the biofilms within the reservoirs to air and wastewater, thus making it possible to achieve sequential aerobic, anoxic and anaerobic conditions in the biofilms.

Abstract: Installation for the treatment of municipal and/or industrial wastewaters comprising a basin that receives the water to be treated and a series of discs (4) having a packing (G) that are parallel and vertical, mounted on a horizontal shaft (5), partially submerged in the water to be treated, and rotated so that the biomass which grows on the surface of the packing of the discs is alternately brought into contact with the water to be treated and oxygen from the air. The configuration of the packing (G) of the discs (4) is chosen so that the developed surface area of the packing in one zone of the disc increases with the distance from this zone to the axis of rotation (X-X).

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 compact biological treatment assembly, apparatus and methods are disclosed, the apparatus including a movable belt biological contactor having selected microbial cultures established thereon. The apparatus further includes a tank having a volume for receipt of wastewater to be treated, first and second drums positioned at the tank each connected to an end of the belt contactor, and a motor or motors together with a controller for rotating the drums cooperatively to move the belt contactor between the drums thereby coiling and uncoiling the belt contactor on the drums.

Abstract: A wastewater treatment facility with a rotating biological contactor (“RBC”) system. The RBC sits in a tank that receives wastewater to be purified. The tank supports a rotatable shaft. One or more stages of rotating disk assembles progressively purify incoming wastewater. Each stage is oriented transversely to the shaft and has a plurality of disk assemblies. Each disk assembly has a number of disks. Each of the disks comprises multiple concentric arcuate segments. The segments are provided with two generally radially extending edges, two circumferential edges that extend between the two radially extending legs, and a front face and a back face. Posts extend from the front and back faces of the disks for stirring wastewater and for offering a site for adherence of biomass suspended in the wastewater. Connecting members interconnect adjacent disks and optionally define a flow channel therebetween.

Abstract: A wastewater treatment facility with a rotating biological contactor (“RBC”) that has a control system. The RBC sits in a tank that receives wastewater to be purified over which a reversible rotatable shaft is supported. One or more stages of rotating disk assembles progressively purify incoming wastewater. Each stage is oriented transversely to the shaft and has a plurality of disk assemblies. Each disk assembly has a number of disks that are sandwiched between end plates. Each of the disks comprises multiple concentric truncated pie-shaped segments.

Abstract: A method for facilitating growth of microbial communities for in-situ bodies of flowing water for the sake of bio-remediating contaminated water and/or producing useful biomass.

Abstract: Disclosed are bioreactor systems and methods to transfer a gaseous composition into a liquid composition in a closed environment. Also disclosed are bioreactor systems and methods for high-density culture of microorganisms and stably culture of activated sludge.

Abstract: Systems, apparatuses, and methods of treating wastewater are provided. In some aspects, a container may be provided and may include a first member, a second member spaced apart from the first member, and media supported by and extending between the first and second members. An organism may be introduced into the container and wastewater may be introduced into the container for treatment. The media may be loop cord media. In other aspects, two containers may be provided and wastewater may be initially introduced into a first container for treatment, removed from the first container, and subsequently introduced into the second container for further treatment. A first species of organism may be present in the first container and a second species of organism may be present in the second container. Methods of using these containers are also provided.

Abstract: An apparatus for aerobic biological treatment of waste water and the like includes a tank configured to retain waste water therein, and a wheel rotatably mounted in the tank. The wheel includes a plurality of chambers arranged in axial succession about the circumference of the wheel. The chambers include openings which are oriented generally upwardly and emerge from the waste water adjacent a top dead center position of the wheel and are oriented generally downwardly and submerged in the waste water adjacent a bottom dead center position of the wheel. An air drive mechanism rotates the wheel, and an air pipe communicates with the air drive mechanism, and is disposed generally below the wheel, and is configured to release air bubbles therefrom after the bottom dead center position. A plurality of bubble connectors are connected with and protrude radially outwardly from the wheel at locations preceding the openings, and are shaped to guide the bubbles from the air pipe through the openings into the chambers.

Abstract: The invention relates to a method for the purification of effluent, in particular, effluent from the paper industry, comprising the following method steps: a) aerobic purification of the effluent using activated sludge in an activated sludge tank (1), b) settling of at least a part of the effluent/activated sludge mixture exiting the activated sludge tank (1) in a settling tank (2), c) separation of a part of the effluent/activated sludge mixture exiting the settling tank in a separating device (3) and d) recycling of at least a part of the activated sludge separated off in steps b) and/or c) into the activated sludge tank (1).

Abstract: A filtering apparatus is provided for filtering raw water containing various impurities and mixtures into purified water, and more particularly, a multistage filtering apparatus is provided in which a rotor for generating vortex are installed in each of multiple layers of filtration membrane stacked within a closed barrel and the rotors are formed in multistage by having different diameter of each rotor so that the power for generating vortex can be remarkably minimized by generating the vertical vortex from top and bottom of the rotary rotor and the horizontal vortex from the outer side of circumference plate of the rotary rotor to be crossed over between membranes to prevent from blocking the pores or remove the deposited pollutants, and the closed-type barrel having multistage of membranes, rotary shaft, and rotary rotors for vortex generation within are constructed as a single module of filter pack, and the filter pack is connected and extended in accordance with required purified capacity so that large s

Abstract: Double-sided, self-cleansing media, and systems incorporating the same for a rotating biological contactor, are described. The media include a disk having cone-shaped members extending perpendicularly from both major faces thereof. Two or more disks lock together, axially about a rotating central shaft, by connecting cone-shaped members spaced throughout the disk surface having a socket at their base to receive the top of the corresponding connecting cone-shaped member on the adjacent disk. The cone-shaped members, by virtue of their length, space the disks a desired distance. Disk segments can link to one another along either straight and/or curved connection portions thereof. The geometry of the media provides free passage of the air and water during each revolution, and while the base disk slices through the air and water, the projecting cone-shaped members enter the air and water perpendicular to the direction of rotation and are washed clear of excess biomass during each rotation.

Abstract: A wastewater treatment system including a biological reactor is disclosed. At least one controlled-reaction-volume module is provided to the biological reactor. The at least one controlled-reaction-volume module includes a fixed-film media for supporting a biological growth. At least one mixer, such as, for example, a high momentum mixer, for communicate a fluid to the at least one controlled-reaction-volume module so that wastewater and the biological growth communicate to thereby treat the wastewater.

Abstract: Various embodiments described herein provide methods and apparatus for releasing treated wastewater into the environment by combining the treated wastewater with a concentrated salty water before discharging the combined water into the environment. The treated wastewater and concentrated salty water may be combined in a ratio that will be less toxic to at least some resident marine life than the treated wastewater alone.

Abstract: A method and system for treating organically contaminated waste water for reuse, by: introducing the waste water into a sedimentation tank to remove a significant portion of the organic contaminants; circulating the waste water from the sedimentation tank to an anoxic mixing chamber for denitrifying the waste water; circulating the waste water from the anoxic mixing chamber to a rotary biological contactor to nitrify the waste water by aeration, and to assimilate organic materials therein by bringing the waste water into contact with a biological medium, to thereby output nitrified waste water; and recirculating a portion of the nitrified waste water outputted from the rotary biological contactor back to the anoxic mixing chamber to enhance the nitrifying and denitrifying of the waste water.

Abstract: A wastewater treatment system is provided that utilizes an equalization tank that stores hydraulic surge flows from the collection system and uses a waterwheel to transfer a maximum flow equal to plant design flow to the downstream treatment systems. The waterwheel aerates the raw wastewater in the equalization tank and prevents it from going septic and causing unacceptable odors. Because the waterwheel cannot transfer more than plant design flow to the downstream treatment elements, these elements will never experience a hydraulic overload.

Abstract: A compact biological treatment assembly, apparatus and methods are disclosed, the apparatus including a movable belt biological contactor having selected microbial cultures established thereon. The apparatus further includes a tank having a volume for receipt of wastewater to be treated, first and second drums positioned at the tank each connected to an end of the belt contactor, and a motor or motors together with a controller for rotating the drums cooperatively to move the belt contactor between the drums thereby coiling and uncoiling the belt contactor on the drums.

Abstract: The invention relates to a method for the purification of effluent, in particular, effluent from the paper industry, comprising the following method steps: a) aerobic purification of the effluent using activated sludge in an activated sludge tank (1), b) settling of at least a part of the effluent/activated sludge mixture exiting the activated sludge tank (1) in a settling tank (2), c) separation of a part of the effluent/activated sludge mixture exiting the settling tank in a separating device (3) and d) recycling of at least a part of the activated sludge separated off in steps b) and/or c) into the activated sludge tank (1).

Abstract: A device is provided for fluid treatment, in particular for waste water treatment. The fluid is led along a surface (3) coated with biological material. A wiper element (5) is provided, which brushes the surface (3) not as a whole, but in paths. The path course is selected such that the coated surface (3) is successively brushed in sections.

Abstract: Processes, methods and systems are provided herein for lowering the concentration of phosphorus in wastewater. The process includes adding a suitable amount of an aluminum-based coagulant/flocculent, for example, an aluminum-silicate coagulant/flocculent product to the wastewater while maintaining the pH of the wastewater at between about 4.5 and about 6.65. This step provides an eventual effluent stream of precipitated aluminum-based, phosphorus-containing flocs dispersed in the wastewater. The next step involves physically removing, as by filtering, the precipitated aluminum-based, phosphorus-containing flocs which is dispersed in the wastewater. These steps are able to provide a wastewater effluent containing less than about 0.03 mg total phosphorus per liter of wastewater. The disclosure also teaches novel methods and systems for carrying out the novel process.

Abstract: In a water distributor device for aquariums, ponds and the like, comprising a main body (30) wherein an impeller (70) is inserted, the impeller (70) is rotated by entering water and is kinematically connected by gears to a nozzle (50) rotatably mounted on the main body (30) and the gears continuously rotates said nozzle (50).

Abstract: Described herein are novel ammonia-oxidizing bacteria as well as isolated nucleotide sequences representative of 16S rDNA of these ammonia-oxidizing bacteria. Particular bacteria of the present invention are tolerant of freshwater environments, saltwater environments or both. Furthermore, in various embodiments, various bacteria of the present invention are capable of surviving a freeze-drying process, and may remain viable thereafter. Methods for preventing or alleviating the accumulation of ammonia in aqueous environments, such as aquaria and wastewater are also provided, using the ammonia-oxidizing bacteria of the present invention.

Abstract: Disclosed herein is an apparatus for purifying sewage and wastewater, including a general automatic impurity treating apparatus; a equalization tank; a distribution tank; a microbe contact tank provided with a rotary activated bacillus contactor comprising a reticular rotator comprising a flat fan-shaped body composed of a synthetic fiber, a first solidification portion 28 formed of Saran latex, which is placed on the body, a spacer insert hole, formed between the body and the first solidification portion and bored such that the hole is integrated with the body and the first solidification portion, and a second solidification portion, formed of Saran latex, which is provided in the spacer insert hole; a measuring tank; a bioreaction tank; a settling tank; a sludge thickener; an aerated liquid circulation pump connected to the bioreaction tank and circulating part of the sewage and wastewater discharged into the settling tank to the distribution tank and the measuring tank; and a sludge returning pump connecte

Abstract: A method and system for wastewater treatment includes flowing a quantity of a wastewater into a first microbubble chamber having a plurality of diffusers for injecting microbubbles into the wastewater to promote oxygenation. The microbubble includes activated sludge for treating the wastewater. The wastewater is then flowed from the first microbubble chamber through a plurality of rotating discs having a biofilm of microorganisms mounted thereon. The discs rotate about a shaft such that a portion of each disc is exposed to air during rotation. The wastewater is the flowed into a second microbubble chamber having a plurality of diffusers for injecting microbubbles into the wastewater. The treated wastewater is then recovered.

Abstract: A membrane supported biofilm reactor uses modules having fine, hollow fibres, for example, made from melt spun thermoplastic polymers treated after spinning to increase their permeability to oxygen, used, for example, in tows or formed into a fabric. In one module, one or more sheets of the fabric are potted into a module to enable oxygen containing gas to be supplied to the lumens of the hollow fibres. Various reactors and processes, for example to treat wastewater, using such modules are described. In one process, oxygen travels through fibers, optionally through an attached biofilm, to oxygenate surrounding water. Mechanical, chemical and biological methods, for example endogenous respiration, are used to control the thickness of the biofilm.

Abstract: A membrane supported biofilm reactor uses modules having fine, hollow fibres, for example, made from melt spun thermoplastic polymers treated after spinning to increase their permeability to oxygen, used, for example, in tows or formed into a fabric. In one module, one or more sheets of the fabric are potted into a module to enable oxygen containing gas to be supplied to the lumens of the hollow fibres. Various reactors and processes, for example to treat wastewater, using such modules are described. Mechanical, chemical and biological methods, for example endogenous respiration, are used to control the thickness of the biofilm.

Abstract: In a device for biological fluid treatment, fluid is led along surfaces coated with microorganisms, which form parts of disks drivable about a rotation axis. The surfaces are formed by recesses lying in the disks and the disks are arranged to one another such that the leading of the fluid is effected through the recesses, and a recess of one disk is delimited in a channel-forming manner by the adjacent other disk movable relative to this.

Abstract: Improved fabricated subcomponents, components and rotating biological contactor embodiments that are assembled from, and that incorporate, such subcomponents and components are achieved. The components comprise tank sections, bulkheads, contactor drums, paddle wheels, shaft assemblies including associated bearings and supports, each of which may be assembled from preformed subcomponents if desired. Rotating biological contactors are assemblable at an installation site, which may be a confined space if desired, by two men with simple tools. In an assembled rotating biological contactor, the shaft assemblies can rotated by an electric motor, by fluidic pressure exerted upon paddle wheel blades, or by both in combination.

Abstract: A packaged wastewater treatment unit has a compact configuration into which all subcomponents may be integrally molded. The compactness of the unit results from the arrangement of the subcomponents within the unit. In one embodiment, a clarifying unit and a basin into which a biological digester is mounted are formed within the top surface of a tank. The interior of the tank contains a collecting compartment separated from a secondary compartment by a baffle. In another embodiment, the housing of a disinfecting unit, such as an ultraviolet or chlorination unit, is also formed within the top surface of the packaged system. A method for treating wastewater includes using a single integrated unit to feed an effluent stream to a collection tank and then transport it to a biological digester, clarifying unit, and disinfecting unit. The effluent stream may be transported through the unit by a series of pumps and spillways. Optionally, the output stream may also be subjected to a sand filtration unit.

Abstract: The invention at hand relates to an improved wastewater treatment plant consisting of a reactor and a filter device, such as for gaining drinking water or wastewater treatment.

Abstract: A packaged wastewater treatment unit has a compact configuration into which all subcomponents may be integrally molded. The compactness of the unit results from the arrangement of the subcomponents within the unit. In one embodiment, a clarifying unit and a basin into which a biological digester is mounted are formed within the top surface of a tank. The interior of the tank contains a collecting compartment separated from a secondary compartment by a baffle. In another embodiment, the housing of a disinfecting unit, such as an ultraviolet or chlorination unit, is also formed within the top surface of the packaged system. A method for treating wastewater includes using a single integrated unit to feed an effluent stream to a collection tank and then transport it to a biological digester, clarifying unit, and disinfecting unit. The effluent stream may be transported through the unit by a series of pumps and spillways. Optionally, the output stream may also be subjected to a sand filtration unit.

Abstract: A flow-through medium for use in a biological digester has a truncated conical shape, a plurality of internal ribs, and optional external ribs. The conical shape of the media creates a venturi-like action for fluid flowing through the media, which increases the tumbling of the media elements against each other and against the wall of the enclosure in which they are contained. Moreover, the conical shape and venturi-like action prevents slough from accumulating within the media elements, allowing it to be washed through the media. A method of treating sewage effluent includes placing the media elements in an enclosure partially submersed in the effluent and rotating the enclosure to expose the media to the effluent and to a source of oxygen.

Abstract: An improved algae scrubber system having a partially submerged rotatable drum (16) wrapped in plastic mesh or algae screen (18). The rotatable drum (16) is supported by a water treatment tank (24). The water treatment tank (24) is in fluid communication with a second tank (32) by way of an influent pipe (28) and an effluent pipe (10). The unique shape and placement of the effluent pipe (10) forces virtually all of the water to pass directly through the algae screen (18). This configuration also allows for an increase in stimulating turbulence for the algae while creating very intimate contact between the algae and waste laden water (34). The water flowing directly through the algae screen (18) discourages over population of herbivorous invertebrates by dislodging them.

Abstract: A process for treating organically contaminated waste water is provided comprising an initial treatment step whereby microorganisms are replicated and either attach to support media or remain suspended in the waste water. The microorganisms reduce the incoming biochemical oxygen demand (BOD) level by consuming the organic contaminants. At least a part of the suspended portion of microorganisms are subsequently removed from the initially treated waste water, and the waste water under goes a further treatment step to further reduce the level of organic contaminants.

Abstract: The device serves for the biological fluid treatment. Fluid is led along surfaces coated with microorganisms, which form parts of disks (19) drivable about their rotation axis, wherein the surfaces are formed by recesses lying in the disks (18, 19), and the disks (18, 19) are arranged to one another such that the leading of the fluid is effected through the recesses, and a recess of one disk (18) is delimited in a channel-forming manner by the adjacent other disk (19) movable relative to this.

Abstract: Rotating biological contactor-type sewage treatment equipment of the present invention comprises a treatment tank 4 for storing sewage to be treated, a rotation shaft 3 which extends across opposed side walls 4a, 4b of the treatment tank 4, a plurality of rotating discs 1 mounted at a predetermined interval on the rotation shaft 3 in such a manner that each disc is partly submerged in the sewage stored in the treatment tank 4, and a driving means for supplying a driving force to the rotation shaft 3 in order to rotate the rotating discs 1. This equipment treats sewage by rotating the rotating discs 1 on which aerobic bacteria are attached, thereby allowing the aerobic bacteria to contact the sewage and aerobically decompose pollutants in the sewage. Each of the rotating discs 1 is composed of n portions of sector-shaped segments 11, wherein n is an integer not less than 1, and each of the sector-shaped segments 11 is composed of two equally divided sector-shaped pieces 11a, 11b.

Abstract: A waste treatment method and apparatus including an aeration basin for holding waste, an aerating device for aerating the waste and an integral clarifier in which sludge particles separate out of the waste, leaving discharge water and recycled sludge. Between the clarifier and the aeration basin there is at least one opening or conduit through which either or both waste from the aeration basin may flow into the clarifier or recycled sludge from the clarifier may flow into the aeration basin. Preferably, the apparatus facilitates both activated sludge and fixed film processes in a single main tank.

Abstract: A biological process is enhanced by a method and apparatus used to contact a biomass with a gas and with a nutrient liquid. A resiliently compressible porous matrix system containing the biomass is mounted in a reaction vessel containing a body of the nutrient liquid and a body of the gas above the body of the liquid. The body of liquid having an upper surface exposed to the body of gas and defining a liquid-gas interface. The resiliently compressible porous matrix system is located in a position in the reaction vessel so that compressible porous matrix system is partly immersed in the nutrient liquid and partly extends above the upper surface of the liquid into the body of gas.

Abstract: The present invention provides an isolated bacterial strain capable of oxidizing nitrite to nitrate and a method of use thereof for preventing or alleviating the accumulation of nitrite in an aqueous medium.

Abstract: A biological filter for filtering a stream of falling liquid, the filter comprising a body movable between a first and a second position, and a first filter portion coupled to the body such that the first filter portion is positioned under the stream when the body is in the first position. The filter further comprises a second filter portion coupled to the body such that the second filter portion is positioned under the stream when the body is in the second position, wherein the body reciprocates between the first and the second positions when located below the stream of liquid.

Abstract: Soil and mud of any kind may be decontaminated of its hazardous substances and petroleum products. The materials are mixed with water for soil and mud washing in a wet-type mixing and grinding mill. The washed out material is separated from the eluate which carries away the pollutants extracted from the soil and mud. The cleaned material can be safely returned to nature. The contaminated eluate is exposed to sorption media, such as lignite (brown coal, wood coal) ground to a particle size of a few microns. The sorption media adsorb the pollutants in the eluate fully. After removing the (solid) sorbens from the (liquid) eluate, they can be disposed of or treated for recycling. The eluate, now practically free of hazardous substances, may be released into surface or ground water, or may be pumped back into the industrial water recirculation system. The apparatus includes a wet-type mill which is fed from a soil and mud staging area and from the water recirculation system.

Abstract: A method for biological purification of wastewater in which nitrogen phosphorous compounds are biologically degraded in a biotank. The biotank is operated with suspended activated sludge and with fixed film biomass for producing purified water that is directly removable from the tank. Oxygen input to the biotank is controlled and regulated for operating the tank under different oxygen environmental conditions. An aerobic zone is formed near the water surface of the tank, and an anoxic zone is formed near the bottom of the tank. At least one transition zone connects the aerobic zone and the anoxic zone. The method produces a total concentration exceeding 3 kilograms of dry solids per cubic meter of suspended activated sludge and fixed film biomass in the tank volume that is used.

Abstract: An apparatus for aerobic biological treatment of waste water is described, in which a great number of carrier members having a large surface area to which microorganisms adhere are movably set in a cylindrical reactor within a given range of height, and the carrier is horizontally moved substantially continuously so that a part of the carrier is cleaned with cleaning air. The partial cleaning system eliminates the disadvantages associated with intermittent cleaning of the whole carrier.