Abstract: A system for recovering fat, oil and grease (FOG) from wastewater has multiple annular flotation zones in a concentric configuration surrounding a central column to create progressively increasing surface areas for FOG and solid particles flotation, and thereby enhance FOG recovery and removal. Each flotation zone is equipped with an independent pressurized micro air and ozone bubbles distribution system. A controlled amount of ozone can be injected into the wastewater along with recirculated effluent and micro-size air bubbles. Upon the release of pressurized air-ozone-water mixture, micro-size bubbles are generated and distributed in each flotation zone to effectively float up FOG and solid particles in the wastewater stream.

Abstract: Disclosed are methods, materials and devices for approximation of blood volume in a fluid, such as in a biological fluid collected during a surgical procedure. The method and devices include the use of a RBC flocculant, such as polyDADMAC, and an approximate blood hematocrit for the type of animal, as well as a calculated RBC packing ratio corresponding to the collection device being used. Also provided is a Blood Indicator Panel (BIP), comprising a series of markings calculated from an observed red blood settlement volume, the average animal type hematocrit, and a calculated RBC packing ratio “?” value for the collection device. Pediatric (about 200 ml or 250 ml size container), adult human (about 1,000 ml-1,500 ml) and veterinary (about 500 ml-2,500 ml) collection containers are also disclosed, that include a RBC flocculant, for use in approximating blood volume in a fluid.

Abstract: A system for effectively removing biochemical oxygen demand (BOD), total suspended solids (TSS), ammonia, total nitrogen (TN), and total phosphorus (TP) from wastewater has integrated multiple physiochemical and biological treatment processes into one unit. This system includes a primary DAF unit, anoxic bio-media treatment zone, and a secondary DAF unit. The bio-media treatment zones may be used to remove BOD and TN and may be divided into a number of functional zones. Each functional zone can develop and accumulate optimized bacteria species and microorganisms based on incoming wastewater BOD and nutrient levels.

Abstract: A horizontal flow water treatment method and wetland biofilter apparatus provides a chamber with impermeable outer walls spaced away from permeable interior walls of a media filtration bed such that a catch basin is formed between the outer walls and the interior walls. The catch basin creates an open area around the perimeter of the interior walls for influent water to fill within the open area before penetrating the filtration media, providing a large surface area for influent water to interact with the media filtration bed. The influent water enters the catch basin in a horizontal flow path to provide for pre-settling of particulates before making contact with the filtration media. The biofilter design increases the available surface area of the media filtration bed by up to four times for a given volume of water, and thereby minimizes the loading or infiltration rate on the media filtration bed.

Abstract: Organic matter digesting apparatus and methods are provided that can include a digestion tank operatively coupled to a vertically aligned gas collection tower and methods that can include providing a biodigesting apparatus; inputting organic matter into the biodigesting apparatus; initiating the biodigesting apparatus; and outputting water, methane gas, and solid carbon-based material.

Abstract: A method to remove oil from an oily water stream includes the step of pressure controlling a release of dissolved gases from the stream as the stream passes through two or more stages of gas flotation treatment. The operating pressure of the first stage of flotation treatment is purposefully reduced relative to that of an upstream unit so that a certain controlled percent volume of dissolved gases is released. The operating pressure of the second stage of flotation treatment is then purposefully reduced relative to that of the first stage so that another controlled percent volume of dissolved gases is released. Any subsequent flotation treatment stage is at a lower operating pressure than that of the previous stage so that the subsequent treatment stage releases a controlled percent volume of dissolved gases. By controlling the operating pressure in this way, overall separation performance is improved.

Abstract: A wastewater treatment system includes independent wastewater treatment facilities. Each of the facilities has a number of wastewater treatment subsystems. A wastewater collection subsystem holds wastewater to be treated. A pump subsystem moves wastewater from a wastewater collector to a filtration subsystem having a bioreacting filter. The filter has a sump and a fluidized-bed filter therein and supports the filter upright. The filter has an upwardly expanding, hollow, conical filter body with filter media. A monitoring subsystem measures wastewater process parameters. Control devices receive control commands and, dependent upon the command received, alter parameters of the wastewater treatment subsystems.

Abstract: This invention refers to a single household waste water treatment plant, based on the SBR principle that uses two tanks, one storage tank (1) and one SBR (2), allowing the significant reduction of size, and in consequence, a low consumption of power, as well as the reduction of transportation volume when several units are transferred, wherein said storage tank (1) and said SBR (2) consist of one truncated cone shape external tank and one internal tank, also with truncated cone shape, wherein the internal tank has lower diameters than the external tank, wherein bases of both tanks are concentric, upon which both tanks generate two volumes, an internal volume that corresponds to the SBR (2), and one external volumetric ring, that will correspond to the storage tank (1); wherein the SBR has in its aeration zone duct (7) supported on legs (12), wherein such duct (7) consists of a truncated cone shaped base (13), in which upper part protrudes a cylinder (14), that will extend to the minimum level and that contains

Abstract: The present invention relates to a method and apparatus for removing organic substances, nitrogen, and phosphorus from highly concentrated waste water, which includes the steps of: stirring organic waste water; mixing the waste water with an added neutralizer; supplying a flocculant to the mixture to flocculate sludge; and separating sludge and water by pneumatic dehydration, thereby continuously removing organic substances, nitrogen, and phosphorus from waste water.

Abstract: Feed water is processed in an anaerobic digester. A solid-liquid separation device, for example a sludge screw thickener, treats a stream drawn from the digester in a recirculation loop. The solids portion is returned to the digester to increase the solids retention time and the TSS concentration in the digester. A liquid portion with less than 5% of the solids in the stream is removed and optionally treated further. The flow rate to the solid-liquid separation device is preferably greater than the influent flow rate. The solid-liquid separation device may receive digestate at a TSS concentration of 4% or more and return a solids portion having a TSS concentration of over 10%. The feed water is preferably one or more industrial waste streams having a COD concentration of 20,000 to 50,000 mg/L and a TSS concentration from 1-5%. The organic loading rate may be 10-12 kg/COD/m3/day.

Abstract: A wastewater treatment apparatus performs both initial rainwater overflow treatment and primary treatment. A wastewater treatment method according to the apparatus, the apparatus modifying an existing primary depositing reservoir to an up-flow high-speed filtration facility, the apparatus using a floating filter and biological filter paper applied to an existing depositing reservoir to perform an initial rainwater treatment. The apparatus can be applied to an existing wastewater treatment facility to eliminate the necessity of installing an additional facility for an initial rainwater treatment facility. The apparatus is further capable of adjusting the flow rate into a biological treatment facility to achieve a target water quality.

Abstract: A flash flocculation tank system having a plurality of tanks and a plurality of settling spheres that are magnetic and treat wastewater and/or landfill leachate and a process for decreasing the amount of time for settling solids in biologically and/or chemically treated wastewater and/or landfill leachate. The plurality of settling spheres each have a rare earth magnet and are calibrated by weight to float, sink, and to be suspending in the treated water or leachate. Insoluble waste solids gain a ferromagnetic quality after attaching to the settling spheres. The flash flocculation tank system with the settling spheres and process improve the settleability rate of the insoluble solids of the treated leachate and also allow for a smaller settling tank.

Abstract: Method for treating a fluid aqueous waste stream comprising a biodegradable organic substance, comprising—feeding said stream into a bioreactor containing a fluid which contains biomass;—reacting the biodegradable organic substance with the biomass in the bioreactor under essentially anaerobic conditions;—taking a first flow from the bioreactor and using the first flow as a feed to a membrane filtration unit, in which said feed is subjected to filtration, thereby forming a permeate stream and a retentate stream;—returning the retentate stream to the bioreactor;—taking a second flow from the bioreactor as feed to a sludge treatment unit, in which sludge treatment unit the second flow is separated into a third flow, having an increased organic substance content compared to the second flow, and a fourth flow, having a decreased organic substance content compared to the second flow.

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: In one embodiment, a bioremediation agent and method of bioremediation of an oil spill are disclosed. The bioremediation agent contains oil-digesting bacteria and bacterial nutrients in a buoyant water semi-insoluble and biodegradable casein product. The bioremediation agent may be distributed by boats or seeded by aircraft to remediate oil from coastlines after an oil spill.

Abstract: A reactor and control method for maximizing nitrogen removal and minimizing aeration requirements through control of transient anoxia and aerobic SRT, repression of NOB, and control of dynamic DO concentrations or aeration interval by keeping the reactor NH4 and NOx concentrations approximately equal. Controls are provided for maximizing the potential for TIN removal through nitrification, limited nitritation, nitritation, denitrification, limited denitritation, denitritation making use of 1) real time measurement of ammonia, nitrite, nitrate, 2) operational DO and the proper use of DO setpoints, and 3) proper implementation of transient anoxia within a wide range of reactor configurations and operating conditions.

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 three phase separator or settling device (2) or a digester (1) including the settling device. The settling device can receive a fluid containing liquid, gas and particulate material. The settling device includes a settling chamber to be filled with this fluid. The device can also include a liquid-discharge (5) for discharging liquid from the settling chamber and fitted close to the liquid level (30), a fluid inlet (6) for supplying the fluid into the settling chamber (3), a particulate material separation device (7) and a sludge outlet (8). A flow of fluid is provided into and out of the settling device and settling chamber. The inlet includes a gas separation device (4) for separating gas from the fluid including channels, the inlet positioned close to the fluid level. The inlet and transition (75) into the settling chamber is arranged to create a pre-separated flow pattern including a generally laminar liquid flow.

Abstract: Feed water is processed in an anaerobic digester. A solid-liquid separation device, for example a sludge screw thickener, treats a stream drawn from the digester in a recirculation loop. The solids portion is returned to the digester to increase the solids retention time and the TSS concentration in the digester. A liquid portion with less than 5% of the solids in the stream is removed and optionally treated further. The flow rate to the solid-liquid separation device is preferably greater than the influent flow rate. The solid-liquid separation device may receive digestate at a TSS concentration of 4% or more and return a solids portion having a TSS concentration of over 10%. The feed water is preferably one or more industrial waste streams having a COD concentration of 20,000 to 50,000 mg/L and a TSS concentration from 1-5%. The organic loading rate may be 10-12 kg/COD/m3/day.

Abstract: A ballasted anaerobic system for treating wastewater including at least one anaerobic treatment reactor. A weighting agent impregnation subsystem is configured to mix weighting agent with the biological flocs to form weighted biological flocs to create a weighted anaerobic sludge blanket in the at least one anaerobic treatment reactor. A weighting agent recovery subsystem is configured to recover the weighting agent from excess sludge and reintroduce the weighting agent to the weighting agent impregnation subsystem.

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: 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 printing and dyeing wastewater treatment and reuse apparatus includes a coarse filter, a regulation pool, a hydraulic sieve, a desulfurization pool, a nanocatalytic electrolyzer, a flocculation pool, a flocculation tank, a settling pool, a flotation device, a biochemical pool, a secondary settling pool, a secondary nanocatalytic electrolyzer, a fine filter, a compressor, a nanomembrane assembly, and a recycling pool. Also provided is a printing and dyeing wastewater treatment and reuse method including steps of desulfurization, nanocatalytic electrolysis, flocculation, biochemical treatment, secondary catalytic electrolysis, filtration, and separation by membrane. The invention allows high CODCr removal rate, reduced chemical agent consumption, reduced sludge formation, thorough treatment, and high water reuse rate.

Abstract: The invention relates to a purifier (100) for the purification of a fluid such as wastewater, the purifier comprising:—a reaction vessel (10) for a fluid, the reaction vessel having a reaction chamber (11) and a bottom (12);—a downer (14) having a top end (91) and a bottom end (92), wherein the top end of the downer is connected to a fluid collector (13) to collect fluid from the reaction vessel (10), and the downer is arranged to transport the fluid towards the bottom (12) of the reaction vessel;—a solids separation device (20) arranged to separate solids from liquid, the solids separation device comprising a fluid inlet (72) arranged to introduce fluid into the solids separation device and a liquid discharge (56) arranged to remove separated liquid from the solids separation device; wherein the fluid inlet of the solids separation device (20) is connected to the bottom end (92) of the downer and the solids separation device is located on or near the bottom (12) of the reaction vessel.

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

Abstract: The present invention provides a process for reducing the start-up time of an aerobic granular sludge reactor, said process comprising starting said reactor with an active biomass comprising fragmented aerobic sludge granules.

Abstract: A ballasted anaerobic system for treating wastewater including at least one anaerobic treatment reactor. A weighting agent impregnation subsystem is configured to mix weighting agent with the biological flocs to form weighted biological flocs to create a weighted anaerobic sludge blanket in the at least one anaerobic treatment reactor. A weighting agent recovery subsystem is configured to recover the weighting agent from excess sludge and reintroduce the weighting agent to the weighting agent impregnation subsystem.

Abstract: A method or process is provided for treating wastewater and producing a polyhydroxyalkanote (PHA)-storing biomass. The method or process entails biologically treating wastewater and in one process a filamentous biomass is selected and caused to proliferate so as to dominate an activated sludge. The filamentous biomass is utilized to treat the wastewater and to remove contaminants therefrom. As a part of this process, there is provided an enhancement for PHA production potential in the said biomass. This entails enhancing the PHA production potential of the filamentous biomass by subjecting the biomass to alternating feast and famine conditions where under feast conditions more biodegradable organic substrate is available to the filamentous biomass than under famine conditions. In another process, wastewater is treated with an activated sludge.

Abstract: A device for the treatment of waste material in a waste water collection system includes an inner core and an outer portion partially surrounding the inner core such that at least one surface of the inner core is exposed. The inner core has a greater water solubility than the outer portion.

Abstract: Disclosed is a method for biological treatment of wastewater in a non-woven membrane bioreactor (MBR) system. The mixed liquor contained in the bioreactor is filtered with a non-woven fabric membrane having a pore size in the range of 0.1 ?m to 5.0 ?m. Membrane fouling is controlled and flux is improved in the non-woven MBR system by adding an effective amount of a water soluble sludge filterability improvement chemical to the mixed liquor.

Abstract: A method of controlling filamentous bacteria responsible for foaming and bulking in wastewater systems with virulent bacteriophage. The method includes, optionally, identification of problematic filamentous bacteria and matching virulent bacteriophage, use of bacteriophage from phage libraries and concentration of filamentous bacteria and bacteriophage from the wastewater to be treated.

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

Abstract: A method and system for treating domestic sewage and organic garbage are provided. The method comprises the steps of: multi-phase separation, retting, generating sewage gas, and optional biological denitrification and dephosphorization, which can convert the domestic sewage and organic garbage into clear water, sewage gas, organic manure and sludge. The system comprises a multi-phase separation device, a retting device, a sewage gas generating device and a biological denitrification and dephosphorization device, which can treat the domestic sewage and organic garbage effectively and environmental friendly to achieve a reduction in pollution emission.

Abstract: A method of controlling filamentous bacteria responsible for foaming and bulking in wastewater systems with virulent bacteriophage. The method includes, optionally, identification of problematic filamentous bacteria and matching virulent bacteriophage, use of bacteriophage from phage libraries and concentration of filamentous bacteria and bacteriophage from the wastewater to be treated.

Abstract: A plant for generating biogas from organic biodegradable material containing liquid and solid components, such as waste products, in particular liquid manure from agricultural enterprises, comprises a biogas generation container (9) having a feed for the degradable material and a biogas collection zone (6) having a biogas outlet, and a flotation separation unit having a microbubble generation unit (15) for separating off the solid components from the liquid components of the degradable material. The flotation separation unit comprises a chamber region (14) which is delimited in the interior of the biogas generation container and essentially active in the direction of gravity and having a closed bottom and an open upper end arranged below the liquid level of the biogas generation container. Clarified liquid form the chamber region and a gas, in particular the biogas from the biogas collection region, can be fed to the microbubble generation unit for charging the liquid with gas.

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: Provided are an apparatus and a method for river water purification using a treatment soil layer and a permeable filtering medium layer. The river water purification apparatus includes a treatment soil layer and a permeable filtering medium layer which are sequentially and alternately stacked. The treatment soil layer includes a plurality of unit soil layers which are arranged at intervals. A reservoir part which stores a predetermined amount of river water and supplies the river water to an inside of the unit soil layer is provided in an upper end part of the unit soil layer. The permeable filtering medium layer has a higher hydraulic conductivity than that of the treatment soil layer. The river water purification apparatus increases a treatment flux of river water regardless of a coefficient of water permeability of soil and effectively removes nitrogen, phosphorus and nutrient salts by stably forming an anaerobic condition.

Abstract: Provided is a filter assembly for a bioremediating catch basin. The filter assembly comprises a container having at least one inlet and at least one outlet; a carrier substance, such as a foam, which carries a microorganism capable of digesting hydrocarbons; and optionally an adsorbent material. The filter assembly also optionally has structures for overflow conditions which allow the exit of water, but not floating contaminants from the catch basin. Also provided is a replaceable cartridge for the filter assembly. Also provided is a method for bioremediation of polluted water.

Abstract: A ballasted anaerobic system for treating wastewater including at least one anaerobic treatment reactor. A weighting agent impregnation subsystem is configured to mix weighting agent with the biological flocs to form weighted biological flocs to create a weighted anaerobic sludge blanket in the at least one anaerobic treatment reactor. A weighting agent recovery subsystem is configured to recover the weighting agent from excess sludge and reintroduce the weighting agent to the weighting agent impregnation subsystem.

Abstract: The present invention provides a water purification apparatus and method using a pressurized micro-filter preprocessed with a coagulation inclined-plate sedimentation reservoir and a pore-control fiber filter for improvement of a recovery rate, which removes the dissolved organic materials and the turbidity of raw water through a preprocess by a flash mixer, a two-stage coagulation reservoir and an inclined-plate sedimentation reservoir, thereby making it possible to reduce the use of coagulants, the generation of sludge by-products, the inflow load of membranes, and the facility size in comparison with the conventional standard water purification processes.

Abstract: A method for removing hydrocarbons from a body of water using an agitating, sucking, microbe and expelling boom is described herein. The method can include attaching the boom to a vessel and disposing the boom in the water. The method can include flowing air into a tubular of the boom to agitate material on the bed. A vacuum pressure can be provided to another tubular of the boom to flow the material to a separator. The separator can separate the hydrocarbons from the material. The method can include flowing microbes and air proximate the bed to remove hydrocarbons and to provide oxygen. The method can include attaching hoses to each tubular and to a distribution manifold, forming an ASME conduit. The ASME conduit can be sunk to the bed while the boom floats at a surface of the body of water.

Abstract: To provide an apparatus for treating oil- and fat-containing wastewater for the purpose of degrading and treating oils and fats within a grease trap, which has the advantages from the viewpoint of a high versatility, and also from the viewpoints of cost and maintenance, and a method of treating oil- and fat-containing wastewater, which efficiently degrades and treats oils and fats within the grease trap.

Abstract: A wastewater treatment method includes the steps of supplying a wastewater influent having nutrients for a population of phototactic heterotrophic microorganisms to an aerated bioreactor. At least a portion of the nutrients is converted into the phototactic heterotrophic microorganism population. The wastewater influent and the phototactic heterotrophic microorganism population together form a bioreactor effluent that is transferred to a light clarifier. The bioreactor effluent is concentrated in the light clarifier to form a low-solids effluent and a high-solids effluent. The concentration is performed by inducing the population of phototactic heterotrophic microorganisms to phototactically self concentrate through exposure to a light having at least one of an intensity and a wavelength sufficient to cause the phototactic heterotrophic microorganism population to migrate away from a source of the light. The high-solids effluent is then dewatered to form a concentrated biomass paste.

Abstract: A method for treating water at a water treatment facility is provided. In one aspect, the water has been circulated through a subsurface formation in a shale oil development area. The subsurface formation may comprise shale that has been spent due to pyrolysis of formation hydrocarbons. The method in one embodiment includes receiving the water at the water treatment facility, and treating the water at the water treatment facility in order to (i) substantially separate oil from the water, (ii) substantially remove organic materials from the water, (iii) substantially reduce hardness and alkalinity of the water, (iv) substantially remove dissolved inorganic solids from the water, and/or (v) substantially remove suspended solids from the water. The method may further includes delivering the water that has been treated at the water treatment facility re-injecting the treated water into the subsurface formation to continue leaching out contaminants from the spent shale.

Abstract: A method of hydrolyzing peptide bonds in waste material from dissolved air flotation (DAF float) wastewater treatment systems is disclosed. The method according to the disclosure comprises controlling the pH of said DAF float; adding a lytic agent to said pH controlled DAF float; and incubating the lytic agent/DAF float mixture. The hydrolyzed peptide bonds allow for the cleaving of oil molecules from protein material thereby increasing oil extraction from wastewater streams.

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 present invention relates to apparatus, methods, and applications for treating wastewater, and more particularly to biological processes for removing pollutants from wastewater.

Abstract: Disclosed is a system for renovating process water, especially during the production of paper. Said system comprises at least one process water renovation unit, at least one of which is provided with an anaerobic reactor spiked with anaerobic microorganisms as well as a lime elimination unit. Also disclosed is a method for renovating process water, particularly during the production of paper, which encompasses at least one process water renovation step in which at least some of the process water continuously delivered to the process water renovation step is subjected to a purification step in an anaerobic reactor that is spiked with anaerobic microorganisms and to a deliming step.

Abstract: A bioremediation device for liquid waste includes a medium for forming a microbial film and for exposing the microbial film to an effluent to decompose a first substance in the effluent and to produce a second substance from the decomposition of first substance. An aerator is coupled to the medium to supply the microbial film with oxygen and to accelerate the effluent around the microbial film.

Abstract: The inventive water treating method and arrangement successively combine at least one step consisting in biological treating at least one part of pollution contained in said waters by a fixed biomass, wherein a bio-cleaned flow logically obtainable at the and of said step, prior to the entry thereof to a next step, contains less than 2 g/l of SS, and at least one stage for carrying out a flocculation-decantation by ballasted flocs consisting in transferring biologically treated flow to a mixing area (2), preferentially at a velocity gradient ranging from 10 s?1 to 1000 s?1, wherein at least one type of denser than water insoluble granulated material is injected and suspended matters are aggregated around said granulated material particles, in transferring the flow issued from the mixing area (2) to a decantation area, wherein the clarified flow and decantation sludges mixed with the granulated material are separated, in extracting granulated material from the decantation sludges, in recycling major part there