JP2010024773A - Water purifying apparatus for sewer pipeline, and water purifying method for sewer pipeline - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water purifying technology in a sewer pipeline for optimizing sewage supplied to a sewage treatment plant so that it may be suitable for biological treatment in the sewage treatment plant. <P>SOLUTION: Water purifying apparatus 1, 20 for a sewer pipeline have water flowing fixed beds 5, 21 arranged at the bottom part in the sewer pipeline so as to be submerged in sewage and allowing nitrifying bacteria to be settled, and oxygen supply means 9, 23 for supplying oxygen into the fixed beds. The water flowing fixed beds on which the nitrifying bacteria can be settled are arranged at the bottom part in the sewer pipeline and submerged in sewage, and oxygen is supplied into the fixed beds to promote breeding of nitrifying bacteria in the fixed beds. Ammonia nitrogen contained in the sewage in the sewer pipeline is thereby oxidized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water purification device for a sewage pipeline and a water purification method for a sewage pipeline that purifies sewage in a sewage pipeline that feeds sewage to a sewage treatment plant, and in particular, sewage treatment by decomposition of organic matter in the sewage pipeline. The present invention relates to a sewage pipe water purification apparatus and a sewage pipe water purification method that are effective in suppressing the quality of sewage that reaches a place from deviating from a range suitable for purification treatment at a sewage treatment plant.

  If sewage discharged from households is discharged into public waters as it is, it will have various adverse effects such as the spread of infectious diseases, lack of oxygen at the discharge destination, deterioration of water quality, and decline in the value of water resources. For this reason, in modern cities, wastewater is designed to be collected in a sewage treatment plant through a sewage pipe and purified before being discharged into a public water area.

  In conventional sewage purification, pathogenic bacteria and organic pollutants were treated. So, separation and removal of suspended solids, biodegradation and disinfection of soluble organic matter were performed at the sewage treatment plant, and sewage treatment was conducted for the sewage pipelines. The main role was to distribute water quickly and smoothly to the site.

  However, in recent years, eutrophication of water areas with nitrogen compounds and phosphorus compounds has become a problem, and removal of nitrogen and phosphorus has also been required as a function of sewage treatment plants. For this reason, as a result of technological development and practical application, nitrogen removal mainly by biological treatment with nitrifying bacteria and denitrifying bacteria and phosphorus removal by biological treatment using aggregated precipitation or phosphorus accumulating bacteria have been implemented. Yes.

  More specifically, as shown in FIG. 1, in the sewage treatment plant A, the sewage S from which the suspended solids have been removed in the first settling basin C through the sand basin B flows into the denitrification tank D and enters the subsequent nitrification tank. The nitrate ions contained in the water refluxed are mixed, and the nitrate ions are converted into nitrogen gas by the reduction reaction of the nitrate ions by the microorganisms that have taken in the organic matter in the sewage, and are removed from the water. On the other hand, nitrogen compounds (mainly ammonia) contained in the sewage S are oxidized in the nitrification tank E to nitrate ions by nitrifying bacteria, and the nitrate ions in the reflux water returned to the previous denitrification tank D are converted into nitrogen gas. Released into the atmosphere. In this way, most of the nitrogen compounds in the sewage are removed from the nitrification tank E (70 to 90%) except for being discharged without being refluxed, and discharged through the second sedimentation tank F and the disinfection tank G. The Here, when the organic substance density | concentration in sewage is low, the organic substance required for the reduction | restoration of nitrate ion will run short, and the nitrogen removal rate in the denitrification tank D will fall. In order to compensate for this, there is a method of artificially adding an organic matter source such as methanol, but the cost naturally increases. The ratio of organic matter of sewage suitable for sewage treatment (expressed in BOD) / nitrogen is theoretically 2.8 or higher, and actually needs to be a ratio of 3-4 or higher (see Non-Patent Document 1). ). Phosphorus removal also does not proceed well unless the concentration of organic matter is high (see Non-Patent Document 1). In other words, for removing nitrogen and removing phosphorus, it is desirable that the organic matter concentration in the sewage flowing into the sewage treatment plant is as high as possible.

  On the other hand, the sewage S in the sewage pipe H naturally flows down in the downflow pipe Ha that occupies most of the pipe, and oxygen is dissolved from the water surface into the sewage in the pipe. Accordingly, microorganisms that breathe oxygen easily grow in the sewage pipe, and the organic matter in the sewage S is oxidatively decomposed by the microorganisms, so that the organic matter concentration in the sewage S decreases. Further, in some of the pumping pipes Hb, sulfate-reducing bacteria that oxidize organic substances using sulfate ions instead of oxygen propagate, and the organic substance concentration is also lowered.

What has been proposed as an attempt to assist purification by adding any operation to the sewage pipe H includes measures for sterilization of the combined sewer (see Patent Document 1 below) and measures for generated hydrogen sulfide. In particular, many patents have been proposed as countermeasures against corrosion and odor caused by hydrogen sulfide generated by sulfate-reducing bacteria in the pumping pipe from the pump station P (see, for example, Patent Documents 2 to 6 below). These are all chemical treatments in which a drug is injected into a sewer line.
Fifth Amendment / Pollution Prevention Technology and Regulations (Water Quality), Pollution Prevention Technology and Regulations Compilation Committee, Supervised by Ministry of International Trade and Industry, Environment Location Bureau JP 2004-122098 A Japanese Patent Publication No. 08-01018 Japanese Patent No. 3395576 JP 2004-027682 A Japanese Patent Laid-Open No. 11-156373 JP 2000-229291 A

  As described above, in order for the biological treatment technology in the sewage treatment plant to be suitably implemented, it is necessary that the organic matter concentration in the sewage is sufficiently higher than the concentration of nitrogen and phosphorus, and biological treatment is economical. Therefore, it is desirable that the sewage reaching the sewage treatment plant can be treated as it is without adding an organic substance such as methanol. However, if eutrophication of sewage treated water is allowed for this purpose, this is a contradiction in promoting prevention of eutrophication in public water bodies and is inappropriate.

  The present invention provides a sewage pipe that can treat sewage in the sewage pipe so that the organic / nitrogen ratio of sewage supplied to the sewage treatment plant through the sewage pipe is suitable for biological treatment in the sewage treatment plant. An object of the present invention is to provide a water purification device for water and a water purification method for a sewage pipe.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and as a result, by providing an environment in which the action of nitrifying bacteria can be used in the sewage in the sewage pipeline, the sewage water quality can be optimized. The inventors have found that this is possible and have completed the present invention.

  According to one aspect of the present invention, a water purifier for a sewage pipe is disposed at the bottom of the sewage pipe so as to be immersed in sewage, and has a water-permeable fixed bed capable of fixing nitrifying bacteria, And an oxygen supply means for supplying oxygen.

  Further, according to one aspect of the present invention, the water purification method for a sewage pipe line is provided with a water-permeable fixed bed capable of fixing nitrifying bacteria at the bottom of the sewage pipe line and immersed in sewage, The gist is to oxidize ammonia nitrogen contained in the sewage of the sewage pipeline by supplying oxygen to promote the growth of nitrifying bacteria in the fixed bed.

  According to the present invention, the oxidation of ammonia by nitrifying bacteria, that is, nitrification proceeds, so that the biological reaction that consumes organic matter is switched from an aerobic reaction that consumes oxygen to an anaerobic reaction that uses nitrate ions, Since nitrogen can be removed as nitrogen gas, it is possible to suppress a decrease in the organic matter / nitrogen ratio of sewage, and sewage suitable for biological reactions in the sewage treatment plant can be supplied from the sewage pipe. Gas generation can also be suppressed.

  Microorganisms that consume organic matter in sewage include aerobic heterotrophic bacteria that take up organic matter and oxygen and release carbon dioxide, and denitrifying bacteria that take up organic matter and nitrate ions and release nitrogen gas and carbon dioxide. is there. Microorganisms that consume nitrogen compounds in sewage include nitrifying bacteria that take in ammonia and oxygen and release nitrate ions, and the aforementioned denitrifying bacteria. Sewage rich in organic matter and capable of absorbing oxygen from the water surface is likely to exist for aerobic heterotrophic bacteria and denitrifying bacteria, but slow-growing nitrifying bacteria are difficult to propagate in running water. Further, under aerobic conditions where supply of nitrate ions is poor, denitrifying bacteria grow in a form using oxygen, and denitrification using nitrate ions does not proceed.

  There are two actions of microorganisms that can reduce the concentration of nitrogen compounds in sewage: 1) uptake by microbial cells, and 2) release of nitrogen gas by denitrification of nitrate ions after nitrification. Oxidizing nitrifying bacteria are slow to grow and do not normally propagate in sewage in sewage pipes that naturally flow down, so the above 2) does not proceed. In addition, the nitrogen compound taken up by the microbial cells of 1) also flows into the sewage treatment plant as it is, and thus does not lead to substantial nitrogen removal. Therefore, neither of the above 1) and 2) usually serves to reduce nitrogen compounds in the sewage in the sewage pipeline. There are no reports of phosphorus-accumulating bacteria that have propagated in sewage pipelines. In comparison, microorganisms that grow faster than nitrifying bacteria (aerobic heterotrophic bacteria group) can propagate while flowing down, and consume and decompose organic matter in sewage using oxygen taken in through the water surface. As a result, the organic substance concentration easily decreases. In order for sewage to be suitable for biological reaction treatment in a sewage treatment plant, the organic matter / nitrogen ratio of the sewage needs to be 3 or more, preferably 4 or more. Even if it decreases, the organic substance / nitrogen ratio does not decrease. That is, it is important to promote the removal of nitrogen compounds in order to optimize sewage. The biggest reason that nitrogen compound concentration does not decrease is that nitrifying bacteria do not propagate. In other words, in order to optimize sewage, it is important to promote the growth of nitrifying bacteria. Once the nitrifying bacteria are propagated, the nitrate ions produced are taken into the nitrogen gas by the denitrifying bacteria in the sewage along with organic matter. Can be converted to

  Therefore, in the water purification method for sewage pipelines of the present invention, in order to promote the growth of nitrifying bacteria having a slow growth rate, a water-permeable fixed bed capable of colonizing microorganisms is installed at the bottom of the sewage pipelines to sewage water. Immerse and supply oxygen in the fixed bed to promote the growth of nitrifying bacteria in the fixed bed. When oxygen is supplied into the fixed bed, the concentration of oxygen in the sewage in the fixed bed is higher than that in the surrounding sewage, making it easier for nitrifying bacteria to propagate. Since nitrifying bacteria are prevented from flowing down to the sewage treatment plant before they grow, even nitrifying bacteria having a slow growth rate settle in the bed and grow. When the growth of nitrifying bacteria in the fixed bed is promoted, ammonia nitrogen contained in the sewage is oxidized to nitrate ions, and nitrate ions are diffused from the fixed bed to the surrounding sewage. Around the fixed bed, the sewage oxygen concentration is lower than in the fixed bed, and microorganisms that can use nitrate ions including denitrifying bacteria take the nitrate ions released from the fixed bed and convert them into nitrogen gas. Is released out of the sewage. Therefore, the nitrogen compound concentration of sewage is reduced. As a result, even if the organic substance concentration is reduced by uptake of denitrifying bacteria or the like, the reduction in the organic substance / nitrogen ratio is relatively suppressed.

  When the dissolved oxygen concentration falls below 0.5 mg-O / L, the nitrification rate of nitrifying bacteria decreases to less than half of the maximum activity, so the dissolved oxygen concentration of sewage in the fixed bed is 0.5 mg-O / L. The oxygen supply into the fixed bed is preferably adjusted so as to be preferably 1 mg-O / L or more. On the other hand, in the sewage outside the fixed bed, it is necessary to suppress the dissolved oxygen concentration in order to suppress aerobic heterotrophic bacteria and increase the activity of denitrifying bacteria as much as possible. The activity of denitrifying bacteria is less than half of the maximum activity when dissolved oxygen is 1.0 mg / L or more (see: Elisabeth VM et al., "SIMULTANEOUS NITRIFICATION AND DENITRIFICATION IN BENCH-SALE SEQUENCING BATCH REACTORS", Wat. Res. vol.30, No.2, pp.277-284, 1996), the dissolved oxygen of sewage outside the fixed bed is 1.0 mg-O / L or less, preferably 0.1 mg-O / L or less. (Ref: Fukunaga and Motegi, “Nitrogen removal in oxidation ditch”, Journal of Sewerage Society, Vol. 21, No. 238, pp. 1-9, 1984). From these points, the dissolved oxygen in the fixed bed is 0.5 mg / L or more, preferably 1 mg-O / L or more, and the outer dissolved oxygen is 1.0 mg-O / L or less, preferably 0.1 mg-O / L. By adjusting the amount of oxygen (air) supplied to the fixed bed so that it is less than or equal to L, the activity of nitrifying bacteria in the fixed bed and the activity of denitrifying bacteria in the outside are each maintained at half or more of the maximum activity The denitrification of nitrate nitrogen by the action of denitrifying bacteria or the like can proceed. As a practical oxygen supply setting so that the dissolved oxygen concentration of the external sewage is 1.0 mg-O / L or less, the dissolved oxygen concentration of the sewage in the fixed bed is 0.5 to 3.0 mg-O / L. It is effective to adjust the supply of oxygen into the fixed bed so that it is in the range of L, and the dissolved oxygen concentration outside the fixed bed is reduced to 1.0 mg-O / L or less by the concentration gradient and nitrifying bacteria uptake. Can be suppressed.

  By the supply of nitrate ions, at least a part of the reaction of microorganisms that take up organic substances in sewage is converted from a reaction using oxygen to a reaction using nitrate. This conversion is important in suppressing the decrease in the organic matter / nitrogen ratio.

  As a trial calculation in conventional sewage, it is assumed that organic matter with an organic matter concentration of 200 mg / L in terms of BOD and nitrogen compound concentration with 50 mg / L in terms of N has been oxidatively decomposed with 50 mg / L of organic matter flowing down the sewer line. Then, the BOD / N ratio of the sewage decreases from 4.0 to 3.0 while flowing through the sewage pipe, and changes to a poor condition for removing nitrogen and phosphorus. On the other hand, by using the water purifier for the sewage pipe of the present invention, 15 mg / L of the nitrogen compound in the sewage pipe is nitrified into nitrate ions, and this uses BOD 45 mg / L organic matter. When it is removed as nitrogen gas by denitrification, when the total amount of organic matter disappeared by oxidative decomposition in the sewage pipe is BOD 50 mg / L, the final BOD / N ratio of sewage is 150/35 = 4 .3. This value is a value suitable for at least nitrogen removal by biological treatment, and it is possible to improve the nitrogen removal efficiency in the sewage treatment plant as compared with the prior art and eliminate the need for artificial addition of organic substances such as methanol. The point to be noted about this trial calculation is that when the total amount of organic matter disappeared by oxidative decomposition with oxygen in the sewage pipe, the effect of suppressing the final decrease in the BOD / N ratio of the sewage is weakened. Suppressing aerobic heterotrophic bacteria by preferential growth of bacteria, and nitrification-denitrification progresses without increasing the total amount of organic matter lost by oxidative degradation by converting microbial activity from oxygen-utilizing to nitric acid-using And can effectively increase the final BOD / N ratio of sewage.

  Below, the sewage-pipe water purification apparatus suitable for implementation of the sewage-pipe purification method mentioned above is demonstrated concretely.

  FIG. 2 shows an example of the sewage pipe water purifier of the present invention set in the sewage pipe, wherein (a) shows a cross section in the sewage pipe radial direction and (b) shows a cross section in the sewage pipe axial direction. Each figure is shown. The sewage pipe water purifier 1 includes a mesh-shaped covering structure 3, a granular filler 5 filled and accommodated in the covering structure 3, an air supply pipe 7 fitted in the filler 5, The air supply pipe 7 is connected to the blower 9. The granular filler 5 is held in a cylindrical shape by the covering structure 3 and constitutes a water-permeable fixed bed provided with a gap between the grains for propagation of microorganisms. The size of the fixed floor is appropriately set to an outer diameter of about 0.2 to 2 m and a length of about 1 to 100 m according to the scale and depth of the sewer pipe, and a fixture (not shown) is attached so as not to move due to water increase. Used to fix to the bottom of the sewer pipe. The particle shape and size of the filler 5, the filling rate, and the mesh shape of the covering structure 3 are such that the gap of the filler 5 and the mesh opening of the covering structure 3 are in the range of 1 to 50 mm, preferably in the range of 5 to 20 mm. In addition, it is appropriately selected so that the porosity is about 50% or more, so that the infiltration of organic solids is prevented and a gap for growing microorganisms is secured. A hollow path is formed below the central axis of the fixed bed by the air supply pipe 7 extending parallel to the axial direction. The air supply pipe 7 has an air diffuser 11 provided with a large number of holes, and the air supplied from the blower 9 installed under the manhole M through the air supply pipe 7 passes through the holes of the air diffuser 11 to fill the filler 5. It is blown into the gap. The number and arrangement of the air diffusers 11 are appropriately set in consideration so that air is evenly supplied to the entire fixed floor. On the other hand, the sewage flowing along the sewage pipeline slightly inclined from the horizontal passes through the mesh-like covering structure 3 and enters the gap between the internal fillers 5 and is dissolved by the air blown from the air diffuser 11. The concentration increases and the sewage between the fillers 5 becomes an aerobic condition. At this time, the soluble organic substance and ammonia are supplied between the fillers 5 through the covering structure 3, but the mesh-like covering structure 3 functions as a filter and is insoluble in sewage (that is, solids). The matter or suspension) is filtered to prevent entry between the fillers 5. In the gap of the filler 5, nitrifying bacteria grow in sewage that is slow due to the flow resistance due to the filler, adheres to the surface of the filler 5, precipitates and holds in the gap of the filler, and is aerobic under ammonia conditions. Is oxidized to nitrate ions. On the other hand, microorganisms that oxidize and decompose organic substances do not propagate as well as conventional sewage pipes because organic solids are difficult to enter the gaps in the filler. For this reason, the competitiveness of nitrifying bacteria is relatively improved, and the nitrifying action is likely to proceed. As nitrification progresses, the generated nitrate ions pass through the mesh of the coating structure 3 and diffuse into the surrounding sewage. In the surrounding sewage, denitrifying bacteria take up nitrate ions in the presence of abundant organic matter. Reduces to nitrogen gas and releases it, then leaves the sewage.

  Accordingly, at least a part of the organic matter that has been conventionally oxidized and decomposed using oxygen or sulfate ions without lowering the concentration of the nitrogen compound is obtained using nitrate ions supplied from the sewage pipe water purification device. It is used by bacteria that oxidize and comes with a decrease in the concentration of nitrogen compounds.

  Since the fixed floor of the water purifier 1 for the sewage pipe in FIG. 2 is a bendable axial body composed of a granular filler loaded in a cylindrical shape in a mesh bag with both ends closed, the sewage pipe It can be installed corresponding to the bending of the road. The shape of the fixed floor is not limited to a cylinder, and may be another axial shape having a different cross-sectional shape such as an elliptical column, a polygonal column, or a partial column such as a semi-column. Since it will occupy only a part of the bottom part of a sewer pipe, if it comprises in such an axial shape, the flow of the sewage at the time of water increase will be hardly inhibited. The material constituting the filler is not particularly limited as long as microorganisms can be fixed, and may be appropriately selected from natural materials such as plant fibers, woody materials, minerals, and synthetic materials such as plastics. The plastic material is easily attached to microorganisms, and is also useful in terms of processing and handling.

  FIG. 3: shows the other example of the water purifier for sewer pipes of this invention, (a) shows the cross section of a sewer pipe radial direction, (b) shows sectional drawing of a sewer pipe axial direction, respectively. The fixed floor of the sewage pipe water purification apparatus 20 is a cylindrical bendable porous body 21 formed of a material having a self-retaining property, and does not require shape retention by a covering structure. Such a fixed bed of the porous body 21 can be composed of an open-cell plastic material such as foamed polyurethane, or a fiber assembly such as a woven or non-woven fabric. When a woven or non-woven fabric is used, For example, it is formed by winding a cloth in a cylindrical shape and closing one end with the cloth. A material in which the pore (gap) size of the porous body 21 is in the range of 1 to 50 mm, preferably in the range of 5 to 20 mm, and the porosity is about 50% or more is appropriately selected. As in the example of FIG. 2, the dimensions of the fixed floor are appropriately set to an outer diameter of about 0.2 to 2 m and a length of about 1 to 100 m according to the scale and depth of the sewage pipe, so as not to move due to water increase. It is fixed to the bottom of the sewer pipe using a fixture (not shown). By configuring in such an axial shape, the fixed floor occupies only a part of the bottom of the sewer pipe, and hardly impedes the flow during water increase. A hollow path extending parallel to the axial direction is provided below the central axis of the porous body 21, and the hollow path is opened at one end and the other end is closed. In the example of FIG. 3, instead of the blower of FIG. 2, a microbubble device 23 that mixes fine bubbles of 1 mm or less into sewage or externally supplied water is used. The microbubble device 23 has a bubble supply pipe 25 provided with a large number of holes (not shown) on the entire circumferential surface, and the bubble supply pipe 25 is fitted into a hollow passage opening at one end of the porous body 21 to form a microbubble. The device 23 and the hollow path of the porous body 21 are connected. The microbubble device 23 is provided with an air intake pipe 26 for taking in air.

  In the sewage water purification apparatus 20 for the sewage pipe in FIG. 3, the porous body 21 prevents the solid organic matter in the sewage from entering the inside, as in the case of the water purification apparatus in FIG. Sewage containing organic matter infiltrates into the porous body 21. In the sewage mixed with microbubbles of air prepared by the microbubble device 23, oxygen easily dissolves in the sewage and the dissolved oxygen concentration increases. This is diffused from the bubble supply pipe 25 to the porous body 21 through the hollow path. When supplied, the dissolved oxygen of the sewage in the porous body 21 increases, and it becomes an aerobic condition and facilitates the growth of nitrifying bacteria. Nitrifying bacteria adhere to the porous body 21 or are precipitated and retained in the pores or gaps, and oxidize ammonia, that is, nitrify. By eliminating solid organic matter, the growth of aerobic heterotrophic bacteria is suppressed as compared with the conventional one, and the activity of nitrifying bacteria is easily improved. The nitrate ions generated by nitrification in the fixed bed composed of the porous body 21 are diffused from the fixed bed composed of the porous body 21 into the sewage around the organic matter, and are removed using the nitrate ions. The action of nitrogen bacteria is promoted and released as nitrogen gas. By the progress of the denitrification reaction by the denitrifying bacteria, the activity of at least a part of the bacteria is converted from the oxygen utilization type to the nitric acid utilization type, and the decrease in the BOD / N ratio of the sewage is suppressed.

  A water tank having a bottom surface of 180 mm × 180 mm was prepared as a sewage pipe simulation facility. A 1 mm mesh netted cylindrical bag is filled with a plastic filler (outer diameter 30φ) molded into a woven fabric, and an air supply pipe connected with a multi-hole diffuser pipe is inserted into the filler along the axial direction. A sensor of a dissolved oxygen meter was attached to the filler, and the mouth of the bag was fastened to the air supply tube to create a cylindrical fixed bed having an outer diameter of 40 mmΦ and a length of 150 mm. A blower was connected to the air supply pipe to form a water purifier for the sewage pipe, and the fixed bed was placed horizontally in the water tank. Water was poured into the water tank so that the water depth was 60 mm and the fixed bed was immersed, and the sensor of the dissolved oxygen meter was also fixed in water at a distance of 70 mm from the fixed bed.

  Air was blown into the fixed bed from the blower at a supply rate of 40 mL / min for 10 minutes, and the dissolved oxygen concentration in the fixed bed and outside was measured to be 3.73 mg-O / L inside the fixed bed and 0.70 mg-- outside. O / L. This is a result in the absence of microorganisms and no water flow, but the dissolved oxygen concentration inside and outside the fixed bed clearly shows that the dissolved oxygen concentration can be adjusted appropriately even in actual sewage.

The schematic block diagram for demonstrating a sewage treatment system. The sewage pipe radial direction sectional drawing (a) and axial direction sectional drawing (b) which show one Embodiment of the water purifier for sewage pipe lines of this invention. The sewage pipe radial direction sectional drawing (a) and axial direction sectional drawing (b) which show one Embodiment of the water purifier for sewage pipe lines of this invention.

Explanation of symbols

A: Sewage treatment plant A, B: Sedimentation basin, C: First sedimentation basin, D: Denitrification tank, E: Nitrification tank F: Second sedimentation tank, G: Disinfection tank, H, Ha, Hb: Sewage pipes P : Pump station, S: sewage, M: manhole 1,20: water purifier for sewage pipe, 3: covering structure, 5: filler 7: air supply pipe, 9: blower, 11: air diffuser 21: porous Body, 23: microbubble device, 25: bubble supply pipe

Claims (18)

  Characterized in that it has a water-permeable fixed bed capable of fixing nitrifying bacteria and is disposed at the bottom of the sewage pipe so as to be immersed in sewage, and oxygen supply means for supplying oxygen into the fixed bed. Water purification equipment for sewage pipes.   The fixed bed is a bendable axial body having a hollow channel extending inside, and the oxygen supply means supplies oxygen to the sewage in the fixed bed by supplying oxygen to the hollow channel. Item 1. A water purifier for a sewage pipeline according to item 1.   The oxygen supply means includes an air supply pipe fitted in a hollow passage of the fixed bed and having an air diffuser, and a blowing device for sending air to the air supply pipe and blowing air from the air diffuser into the fixed bed. The sewage-pipe water purification apparatus of Claim 1 or 2 which has these.   The oxygen supply means has a microbubble device that prepares sewage in which dissolved oxygen is increased by mixing microbubbles of air into the sewage, and the microbubble device is connected to the hollow passage of the fixed bed and is The sewage pipe water purifier according to claim 1 or 2, wherein sewage in which dissolved oxygen is increased is supplied to the airway.   The said fixed floor is a water purification apparatus for sewage pipes in any one of Claims 1-4 comprised with many fillers hold | maintained by a mesh-shaped coating | coated member at an axial shape.   The said fixed bed is a porous body comprised with an open-cell material or a fiber assembly, The water purifier for sewage pipes in any one of Claims 1-4.   The said fixed floor is a water purification apparatus for sewage pipes in any one of Claims 1-6 comprised with a plastics material.   The water purification apparatus for a sewage pipeline according to any one of claims 1 to 7, wherein the fixed bed has a porosity of 50% or more.   By placing a water-permeable fixed bed capable of fixing nitrifying bacteria at the bottom of the sewer pipe and immersing it in sewage, supplying oxygen into the fixed bed to promote the growth of nitrifying bacteria in the fixed bed A method for purifying water for a sewage pipe, characterized by oxidizing ammonia nitrogen contained in the sewage of the sewage pipe.   The water purification method for a sewage pipeline according to claim 9, wherein supply of oxygen to the fixed bed is adjusted so that a dissolved oxygen concentration of sewage in the fixed bed is 0.5 mg-O / L or more.   The dissolved oxygen concentration of sewage in the fixed bed is in the range of 0.5 to 3.0 mg-O / L, and the dissolved oxygen concentration of sewage outside the fixed bed is 1.0 mg-O / L or less. The sewage pipe according to claim 9 or 10, wherein denitrification of nitrite nitrogen and nitrate nitrogen by a denitrifying bacterium proceeds in sewage outside the fixed bed by adjusting supply of oxygen into the fixed bed. Road water purification method.   The fixed bed is a bendable axial body having a hollow path extending inside, and oxygen is provided to sewage in the fixed bed by supplying oxygen to the hollow path. The water purification method for sewage pipes as described in Crab.   The water purification method for a sewage pipe according to any one of claims 9 to 12, wherein the oxygen is supplied by blowing air.   The sewage pipe according to any one of claims 9 to 13, wherein the oxygen is supplied by feeding sewage with increased dissolved oxygen prepared by mixing fine air bubbles into the sewage into the hollow passage of the fixed bed. Road water purification method.   The said fixed floor is a water purification method for sewage pipes in any one of Claims 9-14 comprised by hold | maintaining many fillers in an axial shape with a mesh-shaped coating | coated member.   The water purification method for a sewage conduit according to any one of claims 9 to 14, wherein the fixed bed is a porous body made of an open cell material or a fiber assembly.   The water purification method for a sewage pipe line according to any one of claims 9 to 16, wherein the fixed floor is made of a plastic material.   The water purification method for a sewage pipeline according to any one of claims 9 to 17, wherein the fixed bed has a porosity of 50% or more.

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