Abstract: Treating and conditioning liquid sludge and a solidified sludge cake obtained thereby are disclosed. A first emulsion of sludge is formed in an in-line container fed at a first flow rate Q owing to the impact of the sludge with air injected into the container at a rate Q?, where Q?>5Q, in a first region which has a small volume of less than 0.05 m3. The first emulsion is then transferred into a second region of the container extending over a first length, and is then discharged via a component which generates a head loss in a chamber extending over a second length. A flocculant is injected in order to obtain a second coagulated emulsion, which is at least partially degasified. The matter in suspension in the second emulsion obtained in this way is then filtered or decanted.

Abstract: A sparger device for sparging fluid into a slurry tank includes a hollow elongated body having a nozzle opening for sparging a sparging fluid flow to a slurry tank. The device further includes a needle for opening and closing the nozzle opening, and a control device being arranged to actuate the needle. The control device includes a control chamber partitioned into a first portion and second portion such that a pressure differential between the first portion and the second portion, closes or opens the nozzle opening and prevents slurry backflow from the slurry tank. The second portion may be provided with a control fluid pressure preventing slurry. A flotation apparatus and a flotation system in with such a sparger device are also discussed.

Abstract: Described herein are methods of separating phase separated, neutrally buoyant materials from liquids and apparatuses for carrying out the methods. The methods and apparatuses employ nanobubbles. In certain embodiments, the nanobubbles may be formed in solutions of hydrophobically modified water soluble polymers. The methods result in removal of 90% by weight or more of neutrally buoyant materials from liquids. The methods are useful in certain embodiments for separating neutrally buoyant oily mixtures from water produced by mining operations.

Abstract: The invention relates to a double-layered compacted solid water-purification product, comprising at least one first layer and at least one second layer, characterized in that the first layer comprises at least one flocculating system and at least one dispersion system, the second layer comprises at least one disinfectant which liberates free chlorine on contact with water and at least one excipient for the disinfectant, whereby said excipient releases the disinfectant into the water at a controlled rate such that the combination of excipient and disinfectant releases 0.1 to 100 mg/l of free chlorine per hour. The invention further relates to the method for production of such a product.

Abstract: A multistage dissolved air flotation and advanced oxidation (MDAF-AO) system/method with multi-functions in oil recovery, solids removal, emulsion breaking, and advanced oxidation. Influent, with oil and suspended solids, enters a first stage for oil recovery includes a gas ionizer and an air dissolving pump. A second stage includes of two coagulation/flotation compartments connected in serial to enhance solids removal efficiencies. Micro air bubbles are created by air dissolving pumps in each compartment. A third stage is for the emulsion breaking unit to further remove or recover the emulsified oils. A fourth stage includes advanced oxidation by using ultraviolet (UV) and hydrogen peroxide to oxidize and disinfect the bacteria and microorganisms.

Abstract: A mechanical vessel may effectively and simultaneously displace a first undesired gas from within water with a second desired gas, and remove at least one alkaline species and oily matter from the water. The vessel raises the pH of the water and reduces the lime requirement for subsequent lime softening. The vessel receives the water containing the first gas and passes the water through a series of gasification chambers. Each gasification chamber may have a mechanism that ingests and mixes a second gas into the water thereby physically displacing at least a portion of the first gas into a vapor space at the top of each gasification chamber from which it is subsequently removed. There is an absence of communication between the vapor spaces of adjacent chambers. An acid is added to remove the alkaline species, where the first gas is an optional by-product that is also removed.

Abstract: The present invention relates to a compacted solid product for water purification comprising:—at least a first layer comprising at least a coagulant/flocculant system comprising at least one polyvalent inorganic salt, at least one water-soluble cationic polymer and at least one high-molecular-weight anionic polymer,—at least a second layer comprising at least one disinfectant that releases active chlorine on contact with water, characterized in that said coagulant/flocculant system moreover comprises a sodium alginate. The invention also relates to the method for preparing such a product.

Abstract: A dishwasher is provided having a dishwashing container and a filter system for cleaning dishwashing liquid. The filter system includes a foam volume and the filter system and the dishwashing container are communicated with one another such that at least some of the dishwashing liquid can be discharged from the dishwashing container in association with a washing cycle of the dishwashing machine to the foam volume for passage of the discharged dishwashing liquid through the foam volume. Dishwashing residue contained in the dishwashing liquid is at least partially absorbed or retained by the foam volume such that the fine-grained dirt particles can be filtered out of the dishwashing fluid, a resoiling of the dishwashing fluid or the items to be cleaned can be minimized and the dishwashing result can be improved.

Abstract: Ozone/oxygen gas is mixed with treated seawater at 30% quality foam and injected to the wellhead at the sea floor. At the seafloor, a tank mixing eductor would be used to mix high pressure oxygen bubbles with the oil contaminated seawater by shearing the oil globs into small oil droplets allowing the new surface area to immediately react with the dissolved ozone/oxygen in the seawater. The ozone/oxygen admixture creating an attraction force between the droplets and the oxygen bubbles. As the droplets and bubble rise, they form larger spherical top-hat bubbles that rise faster in the seawater. In the preferred embodiment, the eductor employs a cone shape flow to direct a significant amount of the oil plume into a predictable area that can then be skimmed mechanically for harvesting or destruction.

Abstract: The invention provides a method of improving a flotation separation process. The method involves PAPEMP, a material previously thought to only be of use in controlling scale deposit on surfaces of equipment used in cyanide leaching. In the invention the PAPEMP is added to the flotation separation process for improved sulfide mineral separation. Not only does the addition of PAPEMP improve the overall recovery of sulfide complexed metals in flotation, but by doing so it also reduces the energy requirements and adds other efficiencies to other downstream ore processing and refining steps. This has the added benefit of helping to preserve the environment.

Abstract: A clarification system may comprise a channel having an inlet and an outlet, a length, bottom, and a height sufficient to contain a liquid having a depth. The clarification system may include one or more gas injectors disposed within the channel, configured to inject gas bubbles into a suspension flowing in the channel. In some embodiments, at least one gas injector injects gas bubbles having average or median size that does not exceed 100 microns in diameter. Some gas injectors inject bubbles having mean size below 50 microns. Some gas injectors inject gas via the precipitation of gas bubbles from a supersaturated liquid including a dissolved gas. Certain embodiments may be configured to form a quiet zone, typically near the top of the flowing suspension, in which turbulence may be minimized or substantially eliminated. Certain systems include a plurality of gas injectors disposed at different lengths along the channel.

Abstract: The invention relates to an apparatus and method for more effectively dissolving a gas into a liquid stream. A gas is introduced into a liquid stream, at atmospheric pressure, to create a mixed/dissolved stream. The mixed/dissolved stream is then pressurized to an elevated pressure and directed into a hydrocyclone where the gas is further dissolved and more thoroughly distributed in the liquid thereby creating a more intimately mixed/dissolved stream. The intimately mixed/dissolved stream is then directed to a pressure retention vessel where the liquid is held at a predetermined pressure for a predetermined time period for effectively treating, disinfecting and/or clarifying said intimately mixed/dissolved stream. The treated intimately mixed/dissolved stream can then be directed to further processing steps.

Abstract: Various methods and systems are provided below for the treatment of wastewater. According to various embodiments, treatment of wastewater is accomplished using the oxidative power of ozone gas and the interaction between ozone gas, FOGS, and large amounts of surfactants already present in wastewaters to be treated. According to various embodiments of the invention, a combination of oxidation and UV disinfection is used to provide a fact acting treatment for wastewater. These methods and systems generally enable reduced footprint in relation to the volumes treated, reduced cost, and increased efficiency. Various alternative embodiments are also disclosed.

Abstract: A device for treatment of solids and liquid waste comprising a storage container a comminution unit at least one separation unit, and an electroflotation unit.

Abstract: Recycled waste water is treated to remove contaminants and produce a sludge cake with a high percentage of solids and to produce a treated recycled waste water that can be discharged into a municipal sewer system.

Abstract: A wastewater treatment system for use on marine vessels or land-based applications treats wastewater by solids separation and oxidation. The system includes a solids separation tank, an oxidation tank having a plurality of chambers and a fluid circuit for re-circulating treated wastewater into the solids separation tank and oxidation tank for further treatment. An ozone generator produces ozone which is dissolved in the treated wastewater in the re-circulating fluid conduit and is used for the solids separation and oxidation processes. The treated wastewater is periodically discharged into the environment.

Abstract: A pre-filtration apparatus and system using dissolved oxygen ozone-treated water processed through an oxygen saturator having a flow distributor for even distribution of the water. Fully saturating the water with excess oxygen and injecting this high-pressure mixture into a blender have a lower pressure atmosphere to produce a plurality of micro-bubbles known as white-water. Influent water enter the blender through nozzles aligned with the injection of the high-pressure water to blend with the white-water. The blend passes into a hydrocyclone separator from the bottom, spirals up separating waste water from the clean water. Clean water is discharged; waste water is passed to a recovery unit for further processing and recycled. Volatile gas from dissolved toxic chemicals adsorbed by the micro-bubbles is discharged through a carbon filter recovery process.

Abstract: A flotation plant comprises air supply means with which air bubbles can be supplied to a basin to which untreated water is supplied so as to cause flakes suspended in the untreated water to float by aid of the air bubbles; the air supply means includes strip- or plate-shaped aeration means having perforated membranes and to be installed in the bottom region of said basin.

Abstract: A process for dewatering lime mud in a kraft pulping process is described. The process includes an improvement which comprises adding an effective amount of an alkyleneamine to the lime mud prior to filtration. The preferred alkyleneamine is ethyleneamine, that is, an amine having at least one —(CR2—CR2—NH—)— unit wherein each R independently is H or an alkyl (straight, branched or cyclic) group of from about 1 to about 10 carbon atoms. Ethyleneamines include ethylenediamine, diethylenetriamine, triethylenediamine, triethylenetetramine, tetraethylenepentamine, piperazine, aminoethylpiperazine, and ethyleneamine mixtures such as mixtures of ethyleneamine oligomers having an average molecular weight of about 200-500.

Abstract: Copolymers of polyaspartic acid which are suitable for the inhibition of scale deposition were obtained by reacting maleic acid, an additional polycarboxylic acid and ammonia in a stoichiometric excess, at 120.degree.-350.degree. C., preferably 180.degree.-300.degree. C., to provide copolymers of polysuccinimide. In a second embodiment, a polyamine was added to the reaction mix. These intermediate polysuccinimide copolymers could then be converted to the salts of copolymers of polyaspartic acid by hydrolysis with a hydroxide.Such copolymers are useful in preventing deposition of scale from water and find applications in treating water. Other applications include scale prevention additives for detergents. In addition, such copolymers inhibit dental tartar and plaque formation.

Abstract: A method for recuperating crude oil from the body of a spill. First, the body of the spill is sprayed at low pressure then the same operation is done at a relatively higher pressure of at least 100 p.s.i. After the dispersant is allowed to penetrate the body of the spill for several hours, physical agitation of the body of the spill is induced the use of air compressors operating in the range between 500 and 700 psi causing the crude oil to disperse and come to the surface. The crude oil is then extracted from the spill through the use of skimmers and vacuum suction means and subsequently processed.

Abstract: A method for clarifying a contaminated fluid in a main separator vessel having therein a cyclonic flow chamber. A spiral preliminary spinner introduces the contaminated fluid to be separated in a stratified condition into the cyclonic flow chamber by a tangential inlet so as to establish a swirling body of fluid; the cyclonic flow chamber has concentric shells positioned below the tangential inlet for discharging separated solids to a collection area and separating an oil and water mixture into a fluid flow zone formed by the cyclonic flow chamber and the wall of the separator vessel wherein water and oil are separated by aeration provided by eductors; a vertical outlet port discharges separated oil and gas from the upper portion of the cyclonic flow chamber to a fluid flow zone wherein oil and gas are separated. The separated water, oil, gas and solids are removed through discharge ports.

Abstract: A method of separating desired material from undesired material is provided. The method is performed by forming a slurry of material and introducing it into a specially designed flotation reactor chamber. A foam is generated and introduced into the reactor chamber and dispersed into the slurry. A stream of water is provided to separate the undesired portion of the material from the desired portion of the material that has adhered to the bubbles in the foam.

Abstract: A process for gas entrainment of wastewater in an anaerobic wastewater treatment system includes the steps of withdrawing wastewater from an anaerobic digester and piping it into a flotation container. Thereafter the wastewater is pumped into a free standing tank having pressure in the tank maintained at a predetermined level through the injection into the tank of compressed gas generated by anaerobic digestion occurring in the treatment system. The wastewater is removed from the tank and pumped through a multiple jet configuration wherein gas from the tank is entrained in the wastewater as the water is injected back into the tank. The gas entrained water is then discharged from the tank back into the flotation container where the gas bubbles particles to the surface of the water to form a sludge layer.

Abstract: A method for removing ammonia, or ammonia and phosphates from industrial agricultural or household effluents by causing precipitation as magnesium ammonium phosphate by means of a liquid reagent containing magnesium and phosphate ions and an acid. The effluents have more than 1 gle of ammoniacal nitrogen and the pH is adjusted to between 9 and 11 after addition of the liquid reagent.

Abstract: The present invention relates to a two stage, multi-phase process for the rapid and economical purification of waste water which may contain solid wastes, and which does contain chemical and bacterial wastes wherein the waste water is first intimately intermixed with a gaseous oxidant comprising ozone and oxygen to remove solids, then resaturated with oxidant for the breakdown and destruction for chemical and bacterial wastes, and thereafter a predetermined portion of the treated water is recirculated through the system for retreatment while the remainder is first treated with ultraviolet light and then degassified prior to discharge from the system in its purified state.

Abstract: A unique bubble production system and method for sampling and cleaning la regions of "dirty" or polluted bodies of water, or for otherwise sampling them for other biological activity. This is achieved by the use of millions to trillions of tiny chemical coated particles which are usually dispersed in air by suitable means to effect predetermined patterns of the particles and resultant bubble region as they descend in the water. The particular character of the particles and their selected dispersal mode assure the homogeneous generation of large concentrations of millions to trillions of bubbles throughout a predetermined volume of the water body so as to generate a planned and controlled bubble spectra for a selected applicational purpose. A bubble spectrum is a plot of the number of bubbles per volume as a function of bubble diameter.

Abstract: This invention consists of a method of operation of a Self-Propelled Barge that is capable of supporting six integrated process systems for the continuous recovery of surface and sub-surface Oil or Oil Products spilled into Fresh, Brackish or Sea Water. The six major process systems provided by the invention are as follows: (1) A wave following positioning system that will provide the correct distance below the surface of the Water in order to allow the introduction of a process for the flotation and compaction of surface and sub-surface of Oil by entrained and super saturated dissolved Air. (2) A process system that provides maximum efficiency of flotation and compaction of Oil by providing a recirculated water supply with entrained and super saturated dissolved Air. (3) A process system that provides a Wave following adjustable positioning vacuum collection system for the compacted Oil film on the surface of the Water.

Abstract: A system for separating phases of a liquid stream, comprising a plurality of members each member having an inlet and an outlet such that the outlet of one member is connected to the inlet of another with members being horizontally or vertically stacked in relation to each other.

Abstract: A process and apparatus for separating a liquid phase dispersed in a heavier continuous liquid phase, such as a hydrocarbon dispersion in an aqueous phase, of the floatation type, wherein gas bubbles are generated in the continuous phase to assure ascending entrainment of the dispersed phase, the gas bubbles being formed from a mixture of at least one base gas which is only slightly soluble in the continuous phase, and at least one transfer gas with a higher solubility in the continuous phase, such as instance ammonia, thereby significantly improving the separation yield and efficiency.

Abstract: A method of, and apparatus for, separating phases in a polyphase system is described and particularly in separating oil from produced water by the contact of gas bubbles and oil droplets by a dispersed gas flotation technique. A polyphase system is divided into at least two portions. The pressure of one portion is reduced to form bubbles of a gas, and the two portions are then recombined whereby the bubbles in the mixture enhances flotation, and hence separation of the dispensed phase, e.g. oil, from the continuous phase, e.g. water. The invention has particular application in the oil industry and in other fields where efficient separation is required.

Abstract: In the improved system and method of the present invention, a batch of contaminated oil is deposited into a tank, with the oil preferably being passed through a filter during the depositing step to assist in removal of solids. Once the contaminated coolant has been deposited into the tank, the oil is agitated by injecting several streams of air into the bottom of the tank. This creates several bubble streams which pass upwardly through the coolant toward the surface and, during this passage, agitate the coolant and effect separation of the oil so that it rapidly rises to the coolant surface. The bubble streams are created by different sized orifice member whereby the bubbles of one stream are smaller than the bubbles in another stream.

Abstract: A water clarification process wherein solids are separated by filtration through a porous septum utilizes as a filter precoat a coating of keratin-composition in the form of particles wherein at least 75 weight percent of the particles have a particle size no greater than 2.0 mm. In preferred embodiment, the material to be filtered is first treated with a combination of an organic polymeric flocculant and an organic polymer coagulant.

Abstract: Apparatus for treating water by gaseous diffusion and flotation comprising a single reactor which is separated into at least two compartments. One compartment is used for gas transfer with a pressurized gas diffuser flushed by a liquid current wherein water to be treated is introduced downwardly. The other compartment is in communication with the first compartment by means of an orifice whose opening diameter and orientation are controlled.

Abstract: A process for the separation of foreign matter from a liquid, which process comprises mixing a stream of contaminated liquid containing dissolved gas with a stream of induced gas to provide a multi-phase flow, subjecting the multi-phase flow to turbulence and shearing thereby to produce a well dispersed bubbly liquid stream, passing the bubbly liquid stream into a vessel which contains the liquid contaminated with foreign matter, below the free surface of the liquid, and allowing the bubbles of gas to rise to the surface of the liquid, the surface adherence between the gas bubbles and the particles of foreign matter causing the particles of foreign matter to float to the surface of the liquid.

Abstract: An improvement is provided to the known hot water process for extracting bitumen from mined oil sand. More particularly, a methodology is provided for the production of microbubbles of air, and it has been found that the so-produced microbubbles can be used in the primary flotation/settling step of the hot water process to yield increased bitumen recovery. More particularly, a steam stream and an air stream in admixture are injected via a submerged nozzle into a flowing aqueous stream. A plurality of finely dispersed microbubbles are formed. These microbubbles have a diameter less than about 100 microns. The stream of microbubbles is injected into the diluted aqueous tar sand slurry formed in the hot water process. The injection is practiced following the conditioning step and prior to the introduction of the slurry into the flotation/settling step.

Abstract: Apparatus and method for effecting a chemical reaction, including a mixer/charger for simultaneously mixing and electrically charging a fluid input to produce a charged fluid output, chemical reaction containment vessel for containing ingredients undergoing a chemical reaction separately from the mixer/charger, and a coupling for fluidically coupling the charged fluid output from the mixer/charger to the containment vessel to influence the chemical reaction. The method includes simultaneously mixing and electrically charging a fluid input to produce an electrically charged fluid output, and delivering the electrically charged fluid to a medium undergoing a chemical reaction to influence the chemical reaction thereof.

Abstract: A process for removing dissolved and undissolved oil and chemical additives from waste and/or produced water streams involves contacting a first gas with the produced water stream, the first gas utilizing hydrogen bonding and dipole interactions with the contaminants to remove them from the water. The rise rate of the first gas is accelerated by mixing a second, more buoyant gas with the first gas. The first gas and second gas are recovered by the application of a vacuum to the waste stream after treatment. The first gas is separated from the second gas by compressing and cooling the combined gas stream, venting the majority of the second gas stream while the first gas is liquified, then expanding the first gas before returning it to the flotation vessel. The first and second gases are mixed with the contaminated water stream at line pressure so that mixing is intimate and flotation is accelerated.

Abstract: For water-treatment in swimming pools, cooling towers, hot tubs, and other systems, it is desired to feed various chemicals in small quantities but at optimum rates into the system. In several embodiments of the invention the water is recirculated through the system which usually includes a filter. It has been discovered that the chemicals can be fed by enclosing them in generally spherical plastic capsules suggestive of table tennis balls, but about the size of a base ball. The rate of feeding depends upon the size and number of small holes which are provided, or the user pokes through the shell of the capsule, upon the solubility of the chemical, and upon the flow rate of the water through a strainer, skimmer, or other chamber in the system into which the capsule is introduced. The random orientation of the capsule tends to average out variations.

Abstract: This invention involves a process and apparatus for removing dissolved and undissolved oil and chemical additives from waste and/or produced water streams. The process involves contacting a selected gas with the produced water stream, the selected gas utilizing hydrogen bonding and dipole interactions with the contaminants to remove them from the water. The rise rate of the selected gas is accelerated by mixing natural gas with the selected attractive gas. The selected gas and natural gas are recovered by the application of vacuum to the waste stream after treatment. The selected gas is separated from the natural gas by compressing and cooling the combined gas stream, venting the majority of the natural gas stream while the selected gas is liquified, then expanding the selected gas before returning it to the flotation vessel. Means are also provided for mixing the selected and natural gases with the contaminated water stream at line pressure so that mixing is intimate and flotation is accelerated.

Abstract: A developing or peeling solution for developing or imagewisely peeling an alkali-type photosensitive film containing a suspension of released photosensitive film is regenerated by introducing one or more reagents and a gas for depositing the suspension in floating state and removing the floated deposit by a skimmer from the developing or peeling solution. The regenerated developing or peeling solution can be used again and again for the development or peeling.

Abstract: Disclosed is a process for removing foreign matter and tramp oil from a continuously recirculating metal working fluid. The process includes the use of saturated dissolved air flotation which, contrary to prior belief, is able to effectively remove the foreign matter and tramp oil in a quiescent manner with little or no foaming and without removing or harming any emulsions present in the metal working fluid. The process further includes the use of water soluble organic cationic and anionic polyelectrolytes where desired to flocculate the foreign matter and tramp oil to enhance their removal from the metal working fluid and a process by which the formation of foam at or near the surface of the metal working fluid being clarified is able to be suppressed.

Abstract: The invention relates to a process for removing carbon black from an aqueous suspension obtained by washing a gas containing carbon black with water. To this end, a gas stream comprising hydrocarbons and at least one inert gas is introduced into a suspension having a solids content of from 0.5 to 4% by weight, at a temperature of from 10.degree. to 80.degree. C. In so doing, the carbon black agglomerates and collects on the surface of the suspension water from which it is separated, for example by skimming it off. The gas stream is produced by passing inert gas over the separated carbon black containing the hydrocarbons and heated to 200.degree. to 400.degree. C., the carbon black being converted into a dry, free-flowing material.

Abstract: The method according to the present invention ensures a thermal decontamination of waste waters. The method comprises passing a combustible gas through said waste waters in the presence of surfactants. Said combustible gas is passed in an amount sufficient to convert said waste waters to a combustible foam; the surfactants are added to convert the entire volume of said waste waters to the combustible foam. Then the resulting foam is subjected to combustion.

Abstract: A contaminated carrier liquid in a chamber is cleaned by adding thereto oil particles having a charge and a composition that induces the formation of an hydroxide floc to form an intermediate filtering layer in the chamber. A top clean oil layer is recovered and a bottom clean aqueous layer is recovered. The intermediate layer can be treated to form a composition that can be recycled to form an hydroxide floc.

Abstract: An improved method and apparatus for froth flotation separation of the components of a slurry, having particular utility for the beneficiation of coal by the flotation separation of coal particles from impurities associated therewith such as ash and sulfur. In this arrangement, a spray nozzle is positioned above a flotation tank having a water bath therein, and sprays an input slurry through an aeration zone into the surface of the water. The spraying operation creates a froth on the water surface in which a substantial quantity of particulate matter is floating, while other components of the slurry sink into the water bath. A skimming arrangement skims the froth from the water surface as a cleaned or beneficiated product.

Abstract: An improved method and apparatus for froth flotation separation of the components of a slurry, having particular utility for the beneficiation of coal by the flotation separation of coal particles from impurities associated therewith such as ash and sulfur. In this arrangement, a primary spray nozzle is positioned above a flotation tank having a water bath therein, and sprays an input slurry through an aeration zone into the surface of the water. The spraying operation creates a froth on the water surface in which a substantial quantity of particulate matter is floating, while other components of the slurry sink into the water bath. A skimming arrangement skims the froth from the water surface as a cleaned or beneficiated product. Moreover, a recycling operation is provided wherein particulate materials which do not float after being sprayed through the primary spray nozzle are recycled to a further recycle spray nozzle to provide a second opportunity for recovery of the recycled particles.

Abstract: The present invention relates to a method for removing suspended matter, organic matter, foaming matter and nitrogen compounds in sewage and to an apparatus for the method.The suspended matter and the organic matter are removed by means of first fine bubbles and the foaming matter is removed by means of second bubbles having a larger bubble average diameter. The sewage treated by the first and second bubbles passes through a bed of porous adsorbent polarized by the feed of current, so that nitrogen compounds and the organic matter remained in the sewage are adsorbed and removed. It is also provided with a step for removing the suspended matter and the organic matter remained in the sewage by means of third fine bubbles before transferring the sewage to the bed of adsorbent.