Abstract: In a vertical shaft bioreactor, improved devices and methods are provided for enhanced secondary and/or tertiary treatment of wastewater, including residential, municipal and industrial wastewater. The devices and methods of the invention are useful for enhanced secondary wastewater treatment, including BOD and TSS removal. Tertiary treatment can alternately or additionally be achieved in the bioreactor with nitrification of ammonia, with nitrification and denitrification, and with nitrification, denitrification, and chemical phosphorus removal. A vertical shaft bioreactor is also provided which achieves thermophilic aerobic digestion and pasteurization of sewage sludges, optionally to produce class A biosolids.

Abstract: Treatment apparatus comprising a chamber (11) for treatment of a process fluid and having at least two regions in each of which the process fluid is caused to follow a circulating path, in which the location of openings (13, 14) for introduction and removal of process fluid to and from the chamber and the shape of means defining the paths followed by the components of the process fluid through the chamber is such that the circulating paths followed by the process fluid in the two regions have oppositely directed radial components and the two regions communicate with one another such that process fluid introduced into one region is constrained to flow into the other region before leaving the vessel, at least part of the chamber wall (12′) being formed as a semi-permeable membrane.

Abstract: An improved method for the aerobic thermophilic treatment of organic material of the type in which air is passed through organic matter contained in a reactor, in which at least a portion of the air that has passed through the organic matter in the reactor being captured and again passed through the organic matter.

Abstract: A system and method for treating wastewater including: delivering untreated wastewater into a permeable container disposed in an impoundment. A wastewater input moves untreated wastewater to the interior of the permeable container. Treated wastewater is flowed through the permeable container and is removed via a wastewater output. A method of practicing wastewater treatment, comprising the steps of delivering untreated wastewater into a permeable container contained within an impoundment; treating the wastewater in the permeable container; moving treated wastewater from the interior of the permeable container to a position between the interior of the permeable container and the exterior of the impoundment; and removing the treated wastewater from the impoundment.

Abstract: An apparatus to transfer gas to or from a liquid has a flexible and oxygen permeable but liquid water impermeable membrane, a flexible and gas permeable spacer, an inlet conduit, an outlet conduit and a non-rigid restraint system. When used for treating wastewater, an aerobic biofilm is cultured adjacent the planar elements, an anoxic biofilm is cultivated adjacent the aerobic biofilm and the wastewater is maintained in an anaerobic state. A first reactor for treating wastewater has an anaerobic section, a plurality of gas transfer membrane modules, and an aerobic section. A biofilm is cultivated on the surface of the gas transfer membranes in fluid communication with the anaerobic section. Biological reduction of COD, BOD, nitrogen and phosphorous are achieved. In a second reactor, phosphorous is also removed chemically in a precipitation branch.

Abstract: A standard 20 ft or 40 ft sea-freight shipping container is configured as a septic tank, or as an aerobic trickle filter station. The shipping-container is lined with a watertight shell or liner. The liner may be a preferabricated separate structure inserted into the container, and supported from the container walls. Or, the liner may be actually constructed inside the container, again taking mechanical support from the container walls. The openable doors at the end of the standard container are retained, a wall being added to the shipping-container a foot or two inside the doors to form the tank, leaving a utility room for pipework, valves, pumps, etc.

Abstract: A biofilm support including a plastic biofilm support element having a maximum dimension which does not exceed 50 mm and having a specific gravity of between approximately 0.70-0.91. A method of manufacture of a biofilm support and a waste water treatment system employing the biofilm support are also disclosed.

Abstract: A vertical membrane storage system including a flexible membrane housing having an upper enclosed portion capable of storing a fluid and a lower open portion for receiving the fluid is disclosed. The storage system also includes a flotation tube disposed above and connected to the upper enclosed portion, and an anchor having receiving means for receiving a fluid disposed concentrically therein, whereby the anchor is connected to and encloses the lower open portion of the flexible membrane. The vertical membrane storage system can be used for storing a variety of fluids including, but not limited to, overflow sewage, oil-contaminated water, and the like.

Abstract: Treatment apparatus comprising a treatment chamber (10), for receiving a process fluid, in which there are provided means for introducing gas (19, 20) at a low level within the chamber to create bubbles which drive the process fluid to circulate within the chamber as they rise, in which there are provided means associated with the gas inlet openings for collecting solid particles entrained with the process fluid which sink as a consequence of contact with the bubbles.

Abstract: The invention encompasses polishing systems for polishing semiconductive material substrates, and encompasses methods of cleaning polishing slurry from semiconductive substrate surfaces. In one aspect, the invention includes a method of cleaning a polishing slurry from a substrate surface comprising: a) providing a substrate surface having a polishing slurry in contact therewith; b) providing a liquid; c) injecting a gas into the liquid to increase a total dissolved gas concentration in the liquid; and d) after the injecting, providing the liquid against the substrate surface to displace the polishing slurry from the substrate surface.

Abstract: The present invention relates to a directional aerator having a float, an uptake pipe extending through the float, and a means for pulling a flow of wastewater into the uptake pipe. The wastewater flow is vertically displaced upwardly through the uptake pipe. At least one pair of baffles deflects the flow of wastewater upon discharge. A method of aerating a fluid is also disclosed.

Abstract: A wastewater aeration system that can be pivoted upwardly to expose the treatment basin floor for removal of accumulated grit or other solids. The aeration system includes a blower and a rigid or flexible supply conduit extending into the basin to supply lateral pipes with air. The laterals normally extend horizontally along the basin floor and carry air diffusers which discharge air into the basin. A winch and cable system or other mechanism can be operated to pivot the lateral pipes and diffusers upwardly away from the basin floor so that they are out of the way of equipment used to remove grit from the floor. A vertical track may be provided along a wall of the basin to accommodate raising of the lateral pipes and diffusers out of the basin.

Abstract: A method of treating a site containing contaminants and apparatus are described The method and apparatus sparges the site with an air/ozone gas stream delivered with a hydroperoxide, which is a substantial byproduct of a reaction of a contaminant present in the aquifer or soil formation with the ozone.

Abstract: A collapsible water treatment digester includes a flexible bladder, a frame, and a plurality of filter plates. The flexible bladder is movable from a collapsed position wherein the bladder is folded into a substantially flattened state to an expanded position wherein the bladder forms a water treatment chamber. The frame is connected to the bladder so as to support the bladder in the expanded position. The filter plates are disposed within the water treatment chamber of the bladder so as to cause a substantial portion of the solids from a wastewater stream introduced into the water treatment chamber to produce a reconditioned water stream dischargeable from the bladder.

Abstract: An odor reducing assembly for use in a marine vessel or RV waste holding tank including an aeration tube and an aeration pump. The aeration tube is disposed in a bottom portion of the holding tank. The aeration tube may be provided by a separate aeration tube or may be incorporated into the macerator/discharge pump. The aeration pump is in fluid communication with the aeration tube and supplies pressurized air to the aeration tube during operation of the marine vessel or RV. The aeration tube is disposed in a bottom-most portion of the holding tank and is submerged in sewage. Pressurized air from the aeration pump is injected into the sewage via the aeration tube and creates an oxygen-enriched aerobic environment therein. Air from the holding tank is continuously vented to atmosphere during operation of the aeration pump via a vent in the tank.

Abstract: A filtration apparatus includes a laundry waste sump, a primary 50 micron static screen filter, a 9,000 gallon equalization tank, at least one secondary media/carbon filter, a sludge holding tank with a pump to return excess water to the equalization tank, a backwash pump, an air blower, and a clear well tank water source for backwash. An exemplary embodiment of the invention also includes a surge tank between the primary and secondary filters and a surge tank between the secondary filter and the clear well tank.

Abstract: A self-adjusting fluid surface skimmer and a wastewater treatment system incorporating the same are provided. In one embodiment, the skimmer includes an intake passage and an outlet passage. The intake passage comprises first and second passageways connected by a flexible coupling. A collar is positioned around the first passageway near an intake opening. At least one buoyant member is attached to the collar and facilitates self-adjustment of the skimmer. A gas inlet is disposed in the outlet passage and allows for the movement of gas through the outlet passage, which creates a suction effect in the intake passage. The wastewater treatment system comprises an aeration tank disposed in a settling tank such that a clearance is created between the two tanks. A skimmer according to the present invention is disposed within the clearance. The skimmer enables further removal of solids from treated fluid within the settling tank prior to leaving the treatment system.

Abstract: A water treatment device, method and system with the water treatment device having a container for holding a water treatment material therein with the water treatment device including a shroud extending in a direction generally normal to a flow of debris laden water with the shroud inhibiting direct flow of debris into a water inlet in the water treatment device by directing water and debris over the shroud and around the water treatment device while a portion of the water can be directed laterally into the water treatment material within the water treatment device to thereby purify the water that flows over the water treatment materials with the water treatment device including multiple spaced and positioned water inlets so that the likelihood of the water inlet being completely obstructed is remote.

Abstract: An aerated grit chamber includes an aeration zone in which influent is vigorously aerated and a settling zone separated from the aeration zone by a baffle beneath which wastewater flows from the aeration zone into the settling zone. The aeration causes swirling motion and causes larger grit particles to settle and accumulate in a grit trough on the floor. An inclined plate settler in the upper part of the settling zone causes smaller grit to settle and fall into the grit trough. In order to prevent overly efficient operation at low flow rates and settling of organics with the grit, internal recycling of the wastewater from the settling zone back into the aeration zone is effected, preferably with air lift to induce recycling but also using alternative techniques such as direct pumping.

Abstract: An apparatus for preventing formation of a solid or semi-solid surface layer in liquid waste contained in a wet-well includes an air pump adapted to pump air into the wet-well and an air pump controller configured to activate and deactivate the air pump at selected times. Also included are a plurality of air injectors disposed in the wet-well and operatively coupled to the air pump. The air injectors inject the air into the liquid waste causing a stream of air bubbles to rise in the liquid waste. The air pump controller activates the air pump for a predetermined period of time so that the stream of air bubbles produced within the liquid waste causes turbulence within the liquid waste so as to disrupt and break up solids or semi-solids on a surface of the liquid waste to prevent the formation of the solid or semi-solid surface layer.

Abstract: The present invention is a solar powered aeration system that incorporates a battery. The device can be used for improvement of water bodies for use in aquaculture systems, reservoirs, water storage tanks, fish tanks, artificial ponds and lakes, and the like. The device does not require connection to the electrical power grid and may be used in any location. Further, the device can be used during periods of low oxygen content, which is typically the period of day just before sunrise. Additionally, the device uses a laminar column of water to enhance circulation of the water body. Increased efficiency can be obtained by matching the diffuser to the pump size, which is important in solar powered applications.

Abstract: An apparatus is provided for separation of suspended solid particles from fluids, for separation and mixing of fluids, and for dissolving gases in aqueous fluids. The apparatus employs a grooved ring to divide the fluid stream and impart a high velocity on each of the divided or sub-streams. A grooved ring with any number of grooves that may be spiral in shape is used to create a high velocity circular motion on a divided stream for separation of suspended solid particles by centrifugal force in a cyclone filter and for saturation of liquid with gases in a fluid mixer where gases are introduced through a diffuser. A grooved ring with any number of grooves that may be radial is used in a fluid mixer to divide a stream of fluid, produce a high velocity flow through each groove, introduce a second fluid through an orifice into the first fluid flowing through each groove, and direct the fluid mixture to a center impact zone where the various streams collide to complete the mixing.

Abstract: An object of the present invention is to efficiently remove foam produced in water by the aeration. Further, another object of the present invention is to improve water and air. Said objects can be attained by providing a foam removing apparatus consisting of a core having a spiral groove on its surface and a cylinder in which said core is inserted, and an air-water treating apparatus consisting of an outer cylinder, an inner cylinder inserted in said outer cylinder, a block having gas permeability inserted in said inner cylinder, and a core inserted in said inner cylinder and disposed above said permeable block, to which block an air introducing pipe connecting from the outside, and on the surface of said core a spiral groove being formed.

Abstract: The present invention is a method and system for treating iron-contaminated fluids. The system and method facilitates and uses an approach described herein as an activated iron sludge sequencing batch reactor (“AIS/SBR”) process. The AIS/SBR method oxidizes and removes ferrous iron as iron oxides from iron-contaminated fluids (such as mining-related discharge water, groundwater, surface water and industrial waste streams) and produces an effluent that is substantially devoid of iron and meets standards appropriate for natural discharge or further treatment. The AIS/SBR method of the present invention can be conducted in a single container assembly unit of the present invention, with time-controlled processing, to perform oxidation, precipitation and settling of iron from fluids. The method optionally includes the addition of alkaline material (e.g., limestone) when the initial liquid alkalinity (mg/L as CaCO3) to ferrous iron (mg/L) ratio of the fluid to be treated is less than approximately 1.7.

Abstract: A system and method for removing pollutants from wastewater. The system includes a constructed wetland cell in which the filtered wastewater is flowed generally vertically. The flow of wastewater is unsaturated through the wetland cell to aerate the wastewater. The wastewater may be further aerated by a blower or injector. The treated wastewater from the wetland cell is blended with untreated wastewater, then either recirculated through the wetland cell or conveyed to a disposal system.

Abstract: The invention relates to a device and a method for chemically and physically separating solid materials from a suspension using flotation. A rotationally symmetrical flocculation/flow reactor is provided with outlets in the lower part thereof and is arranged in a separating tank. At least one suspension inlet extends eccentrically into said reactor. The supplied suspension is guided into said reactor. The supplied suspension is guided into the upper area of the flocculation reactor via the suspension inlet. A circular flow is thus created which drains off from the flocculation reactor downwards in a tangential and radial manner over the outer circumference into circularly arranged distribution cells which reinforce the tangential component of the suspension flow when said flow is delivered into the separating tank. In prior art, the flow of the mixture consisting of the suspension and air-sacs extends radially outwards.

Abstract: Apparatus for treatment of sewage on vessels. The apparatus includes at least a first aeration chamber, a settling chamber, a disinfection chamber, and a storage container. In order to provide a multifunctional and efficient apparatus, the aeration chamber, the settling chamber, the disinfection chamber, and the storage container are integrated into the same structure.

Abstract: The Quick Connect Diffuser Assembly of the present invention includes a special saddle in fluid communication with an air distribution header pipe and a diffuser body connected to the special saddle. The saddle is connected to the air distribution header pipe with a two interlocking sections joined on one side with a hinge, and on the other with flanges. The flanges are connected with a wedge piece. The diffuser connects to the upper saddle section with a bayonet type Quick connection. Gas is forced from the air distribution header pipe through an orifice hole in the pipe, then through the saddle and exits the diffuser body through a diffusion membrane. The membrane forms the gas into fine bubbles that aerate liquid contained in a basin. A single saddle assembly is adaptable to mount on either US or Metric pipe, which have different outside diameters, by changing gaskets and an O-ring.

Abstract: A gasification device is described for the introduction of a gas into a liquid, in particular of air into waste water. The gasification device has a blower body element, which carries a membrane made of an elastic material with perforation slits. The gasification device also has a longitudinal ridge arranged in an area located at the top, related to the installation location. When the gas feed is switched off and the hydrostatic pressure of the waste water is imposed, an axial fold of the membrane is formed in this upper area. This area is, at the same time, free of perforation slits.

Abstract: Methods and apparatus employing membrane filtration in biodegradation processes for treatment of wastewater are described. A bioreactor system is described having an equalization system, a membrane bioreactor system, and a controller. Aeration systems for a membrane bioreactor, such as a mixer, and an ultrafilter subsystem are also described, as is a rotary membrane ultrafilter.

Abstract: A method and apparatus for supplying dissolved gases (such as oxygen, ozone, chlorine etc.) for chemical and biological processes is described. The methods and apparatus described are particularly suitable for use in the biodegradation of organic matter (such as in municipal and industrial wastewater treatment), and other uses. The apparatus may comprise a dissolved gas supply system.

Abstract: The present invention is related to a method for treating high-concentrated organic wastewater, such as night soil or livestock wastewater, which has high levels of nitrogen and phosphorous. In particular, it is related to a method for treating night soil or livestock wastewater having high levels of nitrogen and phosphorous, comprising an anaerobic ammonium oxidizing (Anammox) step and a biopond step. The process for treating wastewater according to the present invention provides good efficiency in removing organic material and nutrients.

Abstract: Mineral contaminants are removed from water in a system in which water is sprayed into an air head at the top of a tank through a diffuser and withdrawn through a pick-up tube. A solenoid valve operates to allows air from a compressor to flow into the top of the tank through a shuttle valve which is opened by the air pressure. Simultaneously a drain valve connected to the shuttle valve opens a drain, venting water and air from the tank. The shuttle valve, closed by the solenoid valve, closes the air supply line and connecting the shuttle valve to atmosphere, and pressure within the aeration tank can close the shuttle valve, which causes closing of the drain valve. The part of the valve which opens the drain is made responsive to excess pressure within the air tank to open the drain and so acts as a pressure relief valve.

Abstract: A sludge digesting method uses a mixing tank providing an integral ceiling, interior wall surface and a floor surface. A vertical beam supports a mixing device engaged for movement along the vertical beam. A plurality of sparger jets protrudes from the wall surface for delivering an oxygen gas flow directly into the interior of the sludge. A second plurality of sparger jets terminates at the mixing tank floor surface for delivering oxygen gas into the mixing tank and a plurality of bubbling diffusers in a circle ⅔ of the diameter of the tank protrudes upwardly from the floor surface for delivering further oxygen gas flow into the mixing tank. The method provides for mixing and entraining oxygen into a process sludge, in an amount of between 4-45 ppm, to accelerate digestion as a batch or continuous process.

Abstract: An integrated biological treatment process and bioreactor system provides means for simultaneous removal of biodegradable solids (TSS), nitrogen (N) and phosphate (P) from water and wastewater. The system comprises microbial consortia immobilized in separate bioreactors for anaerobic processes, P removal, denitrification and, optionally, BOD removal and polishing.

Abstract: The method, in which the water to be treated is partly oxygenated by a specific aeration carried out before percolation through a biofilter having a bacteria-supporting bed of filtering material, has a measurement stage of at least one parameter constituted by the oxidation-reduction potential of the aerated water before passage into the biofilter, a transmission stage of measurement signals to a computer and comparison of the signal representative of the value of the measured parameter with at least one lower limit set in function of the measurement carried out in a second stage for measuring a parameter representative of the pH and a stage for correcting the air flow by a signal determined by the computer in function of the two preceding stages.

Abstract: A water filtering system includes: a water intake system including a plurality of inlets in fluid communication with a water intake pump; and a containment/exclusion boom including (i) a support system positioned in a body of water, (ii) a curtain including a sheet of flexible fabric material that allows movement of water therethrough, the curtain having upper and lower ends with the upper end being connected to the support system, and (iii) means for maintaining the lower end of the curtain substantially against the floor of a body of water; wherein the curtain surrounds substantially all of the plurality of inlets and wherein, upon operation of the water intake pump, water is drawn through the curtain at which time the water is filtered, and subsequently filtered water is drawn through the plurality of inlets for delivery into the water intake system.

Abstract: An apparatus for dispersing a gas in a liquid or slurry has a reaction vessel with an inner zone for the downward flow of liquid, an outer zone for the upward flow of liquid, a plurality of aerators in the outer zone and a propeller to induce downward flow in the inner zone and promote mixing and circulation of the liquid/slurry. The apparatus is particularly suitable for use in the bacterial decomposition of organic waste matter, for efficiently aerating large volumes of waste/water slurries.

Abstract: An odor reducing assembly for use in a marine vessel or RV waste holding tank including an aeration tube and an aeration pump. The aeration tube is disposed in a bottom portion of the holding tank. The aeration tube may be provided by a separate aeration tube or may be incorporated into the macerator/discharge pump. The aeration pump is in fluid communication with the aeration tube and supplies pressurized air to the aeration tube during operation of the marine vessel or RV. The aeration tube is disposed in a bottom-most portion of the holding tank and is submerged in sewage. Pressurized air from the aeration pump is injected into the sewage via the aeration tube and creates an oxygen-enriched aerobic environment therein. Air from the holding tank is continuously vented to atmosphere during operation of the aeration pump via a vent in the tank.

Abstract: A sludge digester comprises a mixing tank providing an integral ceiling, interior wall surface and a floor surface. A vertical beam supports a mixing device engaged for movement along the vertical beam. A plurality of sparger jets protrudes from the wall surface for delivering an oxygen gas flow directly into the interior of the sludge. A second plurality of sparger jets terminates at the mixing tank floor surface for delivering oxygen gas into the mixing tank and a plurality of bubbling diffusers protrudes upwardly from the floor surface for delivering further oxygen gas flow into the mixing tank.

Abstract: A fine bubble diffuser membrane used in the aeration of wastewater is treated with biocide to inhibit growth and accumulation of biological materials on the membrane. The membrane may be constructed of EPDM rubber or urethane. The biocide may be carbolic acid either dispersed throughout the membrane or applied as a coating on the surface of the membrane exposed to the wastewater. The membrane is a flexible and elastic structure impervious to liquid and provided with slits that close to prevent wastewater inflow in the absence of aeration and open in response to aeration pressure to discharge air into the wastewater.

Abstract: An aerobic treatment system for wastewater is disclosed herein. The aerobic treatment system is comprised of a basin, which receives wastewater through an inlet pipe, the inlet pipe depositing the untreated wastewater to the lower portion of the basin. The wastewater must then flow from the lower portion of the interior of the basin through a fibrous filter and through an outlet filter to the outlet section of the aerobic treatment system. While resident within the lower portion of the basin, the wastewater is treated through aeration by an insertion of air through an air inlet pipe and diffusing the air within the untreated wastewater below the fibrous filter. The entire aerobic treatment system of the present invention is designed such that the filtering mechanisms may be readily removed or cleaned on a routine basis by the user.

Abstract: The Diffusion Bar Aerobic Treatment Plant (“DBATP”) is a device which processes sewage for buildings which are not connected to municipal sewer lines. It is comprised of a pre-tank which captures trash and allows anaerobic microorganisms to begin breaking down the sewage, an aerobic tank where aerobic microorganisms digest the sewage, and a post-tank which acts as a gravity separating clarifier in which solid particulate contaminants settle downward, leaving a clean effluent for discharge to the environment. The aerobic tank encompasses a diffusion bar, which emits air bubbles that activate and stimulate the aerobic microorganisms.

Abstract: An embodiment of the present invention relates to a biological process for continues purification of wastewater by converting its constituents to a solid form that can be easily separated using retainable biological catalysts and a novel reactor hereafter referred to as “Reverse Fluidised Loop Reactor” (RFLR) for performing the above said process.

Abstract: Method and process for dramatically increasing mixing, energy and operating efficiency of wastewater treatment plants at reduced capital and operating cost per unit volume.

Abstract: The invention relates to the use of special plastic panels comprising integrated cavities as what are termed separator plates for plate separators in sewage treatment.

Abstract: An odor control apparatus for a facultative lagoon, and a facultative lagoon created and maintained thereby. The apparatus includes an aerator and a cover. The aerator can include a body with an inlet and an outlet and a support such as a float. The inlet and outlet are submerged slightly beneath the surface of the material in the lagoon. Air supplied under pressure to the aerator diffuses oxygen into the aerobic layer of the lagoon. The dissolved oxygen is used in the biodegradation of the hazardous and odorous gases of the waste material that would otherwise be emitted into the atmosphere. The cover is either porous or non-porous and covers some or substantially all of the lagoon surface. The cover promotes accumulation and concentration of desirable odor degrading bacteria in the lagoon.

Abstract: The invention relates generally to a process and apparatus for treating biosolids resulting from the treatment of biological wastewater streams. The invention relates to autothermal aerobic treatment of biosolids where temperature is controlled by adjusting the amount of shear generated through jet aeration devices. The invention provides for a truly aerobic environment under which thermophilic microorganisms will thrive. The invention also relates to a method and apparatus for controlling foam generated in a treatment reactor.

Abstract: The present invention is generally directed to a process and system for treating animal waste. More particularly, the present invention is directed to a process and system for treating animal waste effluent with ozone to decompose the organic material within and improve the odor of the animal waste. The process of the present invention also reduces biochemical oxygen demand, chemical oxygen demand, total bacterial content and coliform bacterial count of the animal waste. The process of this present invention comprises collecting an animal waste solution, containing a mixture of water and animal fecal material; contacting the waste solution with ozone in an amount sufficient to oxidize at least a portion of the organic material contained within; and feeding the ozone treated waste solution to a solids separating device prior to collecting the waste solution in a biobasin or, alternatively, recycling the ozone treated waste solution for use as a source of irrigation or flushwater.

Abstract: A method for treating waste water and a plant designed for preventing the precipitation of carriers under the air blower installed for reaction tank or aeration tank, wherein the plant comprises an aeration tank 1 containing the carriers 2 for growing microorganism for biological treatment of waste water or the subunit 1a joined with the aeration tank through a partition wall 4 including the screen capable of separating the carriers 2, air blower 3 provided for the aeration tank or the subunit of the aeration tank, air bubble generator 5 or submerged stirrer provided under the air blower 3 for creating the flow of water so that the carriers 2 under the blower 3 can be liquidized by the flow of water created by the air bubble generator or the submerged stirrer to prevent the precipitation of the carriers 2 under the air blower 3, whereby not only the precipitation of the carriers under the air blower 3 can be prevented but also the water treatment efficiency and capacity meeting the designed numerical requirem