JP5952132B2 - Phosphorus removal and collection apparatus and phosphorus removal and collection method - Google Patents

Description

  The present invention relates to a phosphorus removal / recovery device for reacting an object to be processed such as phosphate ion and ammonium ion waste water or sludge with a magnesium compound and recovering phosphorus of the object to be processed as magnesium ammonium phosphate (MAP) solid particles. And a phosphorus removal and recovery method.

  In recent years, the discharge of phosphate ions, which is a factor of eutrophication in closed waters, has become a problem. In particular, wastewater containing high concentrations of phosphate ions and ammonium ions, such as wastewater discharged from digested sludge at the sewage treatment plant and digested sludge dehydrated filtrate, is returned to the water treatment system as return water. Phosphorus will flow out into the sewage effluent from the limit of the amount of phosphorus biologically removed in the aeration tank, causing eutrophication of the water area.

  In addition, such waste water also has problems such as blockage of equipment such as piping because phosphate ions and ammonium ions react with magnesium ions to generate MAP scale.

  On the other hand, phosphorus, one of the depleted resources, is mostly refined from phosphorus ore, but in recent years the price of phosphorus ore has been rising due to the decrease in high-quality phosphorus ore and the inclusion policy of phosphorus ore exporting countries. Therefore, techniques for recovering phosphorus contained in sewage and domestic wastewater with high efficiency are being studied.

  Here, conventionally, as a method for removing phosphorus from wastewater containing high concentrations of phosphate ions and ammonium ions, a coagulation separation method in which a metal salt such as an aluminum salt or an iron salt is reacted with phosphorus, a species such as phosphate ore or bone charcoal Crystallization method (catalytic dephosphorization method) in which phosphorus is precipitated in the form of hydroxyapatite on crystals, biological dephosphorization method utilizing the excessive intake of microorganisms by phosphorus, and phosphorus using a phosphorus adsorbent such as activated alumina For example, there is a method of adsorbing and removing.

  However, these phosphorus removal methods cannot effectively use the removed phosphorus. Therefore, as a method for effectively using the removed phosphorus, there is known a granulation dephosphorization method (MAP method) in which magnesium is added to target waste water or sludge, and phosphorus is precipitated as magnesium ammonium phosphate (MAP method). For example, see Patent Document 1 and Patent Document 2.)

  Moreover, as a granulation dephosphorization apparatus for granulating magnesium ammonium phosphate by the granulation dephosphorization method, a gas blowing tube for stirring is used at the bottom of the granulation tower, and the solid particles and waste water are granulated to the granulation tower. There is known a structure in which a solid particle discharge pipe for extraction is provided outside and a cylinder for airlift is provided inside the granulation tower (see, for example, Patent Document 3).

Japanese Patent No. 3537495 Japanese Patent No. 3649471 JP-A-8-24875

  However, in the granulation dephosphorization method and the granulation dephosphorization apparatus described above, since the stirring gas blowing tube is connected to the bottom of the reaction tower, a part of the gas supplied from the stirring gas blowing tube is There is a possibility that the outside of the air lift cylinder inside the granulation tower is raised and the stirring effect by the gas is lowered.

  And if the stirring effect falls, the solid particle of magnesium ammonium phosphate will be hard to grow, and the recovery rate of a solid particle will fall.

  In addition, the gas rising above the outside of the cylindrical body disturbs the gravity precipitation of the magnesium ammonium phosphate solid particles at the top of the reaction tower, so that the precipitation separation is difficult to proceed and the solid particle recovery rate is reduced. There is a possibility of doing.

  This invention is made | formed in view of such a point, and it aims at providing the phosphorus removal collection | recovery apparatus and phosphorus removal collection | recovery method which can collect | recover the solid particles of a magnesium ammonium phosphate crystal efficiently.

  The phosphorus removal / recovery device according to claim 1 is made to react with an object to be processed containing phosphate ions and ammonium ions and a magnesium compound to recover the phosphorus of the object to be processed as solid particles of magnesium ammonium phosphate crystals. A phosphorus removal and recovery apparatus, a reaction tower, a cylindrical reaction cylinder provided inside the reaction tower, a workpiece supply means for supplying a workpiece into the reaction cylinder, and the reaction cylinder Magnesium compound supply means for supplying a magnesium compound into the body, aeration gas supply means for supplying an aeration gas upward into the reaction cylinder, and consolidation for supplying an anti-consolidation gas into the reaction tower A gas supply means for prevention and connected to the bottom of the reaction tower for recovering solid particles of magnesium ammonium phosphate crystals produced in the reaction tower Body particle recovery means, and an outflow means for flowing out the processed product from which phosphorus has been removed, located above the reaction tower, the reaction tower comprising a cylindrical reaction tower straight body section, A cylindrical reaction tower conical part disposed at the lower part of the reaction tower straight body and having a bottom diameter reduced toward the bottom, and an upper part of the reaction tower straight body part. A cylindrical reaction tower precipitation cone reduced in diameter toward the cylinder, and a cylindrical reaction tower precipitation cylinder arranged at the top of the reaction tower precipitation cone to separate the treated product and magnesium ammonium phosphate crystals by precipitation And at least one inclined plate is provided inside the reaction tower precipitation straight body, and a cylindrical first cylinder is provided in the reaction tower precipitation cone. A cylindrical second cylindrical body is provided above the cylindrical body, and the first cylindrical body and the second cylindrical body are provided. A cylindrical main body and a tapered portion connected to the lower end of the cylindrical main body and having a diameter increasing downward, between the tapered portion of the first cylindrical body and the side surface of the reaction tower precipitation conical portion. A slit is formed, and an upper slit is formed between the tapered portion of the second cylinder and the cylinder main body of the first cylinder, and the upper slit is positioned below the reaction column precipitation straight body. The reaction cylinder is arranged from the inside of the reaction tower cone to the second cylinder, the upper end is located above the upper slit, and the lower end is from the reaction tower straight body. The aeration gas supply means is located at a lower end, and has an aeration gas supply pipe whose tip is disposed below the reaction cylinder in the reaction tower, and the anti-consolidation gas supply means includes the It has an anti-consolidation gas supply pipe connected to the bottom of the reaction tower .

  The phosphorus removal and recovery method according to claim 2 is a process in which phosphate ions and ammonium ions are treated with a magnesium compound and the phosphate ions of the workpiece are recovered as magnesium ammonium phosphate solid particles. A method for removing and collecting phosphorus, wherein the phosphorus removing and collecting apparatus according to claim 1 is used.

  According to the present invention, since the inclined plate is provided in the reaction tower precipitation straight body part, it is possible to improve the precipitation separation effect in the reaction tower precipitation straight body part. In addition, since the first cylinder and the second cylinder have the tapered portion, even if the gas supplied from the aeration gas supply means rises outside the reaction cylinder, the gas is caused to flow at the tapered portion. It can guide to the 1st cylinder and the 2nd cylinder, and can prevent the inhibition of the precipitation separation in the reaction tower precipitation straight body part. Therefore, solid particles of magnesium ammonium phosphate crystals can be efficiently recovered.

It is a block diagram of the phosphorus removal collection | recovery apparatus which concerns on one embodiment of this invention.

  Hereinafter, the configuration of an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, reference numeral 1 denotes a phosphorus removal / recovery device. The phosphorus removal / recovery device 1 separates and recovers phosphorus from an object to be treated such as waste water or sludge containing phosphate ions and ammonium ions. Specifically, the phosphorus removal / recovery device 1 recovers phosphorus of the object to be processed as solid particles of magnesium ammonium phosphate crystals by reacting the object to be processed with the magnesium compound.

  The phosphorus removal and recovery apparatus 1 includes a reaction tower 2 that generates solid particles of magnesium ammonium phosphate crystals.

  Inside the reaction tower 2, for example, a cylinder such as a cylinder, and a reaction cylinder 3 for reacting an object to be processed and a magnesium compound are provided along the axial direction of the reaction tower 2.

  Further, the reaction column 2 is provided with an object supply means 4 for supplying an object to be processed into the reaction cylinder 3 from the lower side which is one side in the axial direction of the reaction cylinder 3.

  Further, the reaction tower 2 is provided with a magnesium compound supply means 5 for supplying a magnesium compound into the reaction cylinder 3 from the upper side which is the other side in the axial direction of the reaction cylinder 3.

  The reaction tower 2 is provided with an alkaline agent supply means 6 for supplying an alkaline agent into the reaction cylinder 3 from the upper side of the reaction cylinder 3.

  Further, the reaction tower 2 is provided with an aeration gas supply means 7 for supplying an aeration gas upward from the lower side of the reaction cylinder 3 into the reaction cylinder 3.

  Further, a solid particle recovery means 8 for recovering solid particles of magnesium ammonium phosphate crystals generated and precipitated in the reaction tower 2 is provided at the bottom of the reaction tower 2.

  Further, a gas supply means 9 for preventing consolidation is provided at the bottom of the reaction tower 2 to prevent the accumulated solid particles of magnesium ammonium phosphate crystals from being consolidated.

  In addition, on the upper part of the reaction tower 2, there is provided an outflow means 10 for outflowing a treatment product such as a treatment liquid and treated sludge from which phosphorus has been removed to the outside of the reaction tower 2.

  The workpiece supply means 4 has a workpiece supply pipe 11 whose tip is positioned below the reaction cylinder 3 in the reaction tower 2. In addition, especially as a to-be-processed object, the waste water or sludge etc. which contained the phosphate ion of high concentration can be processed suitably. In addition, as such wastewater or sludge, for example, digested sludge in a sewage treatment plant, desorbed liquid or dehydrated filtrate of this digested sludge, methane fermentation desorbed liquid, solid-liquid separation liquid of human waste or septic tank sludge, and Livestock sewage, which is waste water discharged from livestock houses, is assumed.

  The magnesium compound supply means 5 has a magnesium compound supply pipe 12 whose tip is positioned above the reaction cylinder 3 in the reaction tower 2. The magnesium compound is preferably a magnesium agent such as magnesium chloride, magnesium hydroxide, magnesium oxide, magnesium sulfate, and magnesium carbonate. Magnesium hydroxide is preferable in view of cost, but magnesium ions such as seawater are preferred. It may be contained.

  The alkaline agent supply means 6 has an alkaline agent supply pipe 13 whose tip is positioned above the reaction cylinder 3 in the reaction tower 2 and is alkali-free as required when the workpiece and the magnesium compound are reacted. The agent is supplied. For example, caustic soda is used as the alkaline agent.

  The aeration gas supply means 7 has an aeration gas supply pipe 14 whose tip is located below the reaction cylinder 3 in the reaction tower 2. The tip of the aeration gas supply pipe 14 is positioned below the tip of the workpiece supply pipe 11 below the reaction cylinder 3, and the aeration gas supplied from the aeration gas supply means 7. As the inside of the reaction cylinder 3 rises, the object to be processed rises inside the reaction cylinder 3 by the air lift action. The gas for aeration is not particularly limited, but for example, a gas having a low carbon dioxide content such as air is preferable.

  The solid particle recovery means 8 has a recovery pipe 15 and an opening / closing means 16 such as a valve or a valve body for operating the opening / closing of the recovery pipe 15, and the recovery pipe 15 is opened by the opening / closing means 16. Thus, solid particles of magnesium ammonium phosphate crystals are recovered.

  The consolidation prevention gas supply means 9 has a consolidation prevention gas supply pipe 17 branched from the aeration gas supply pipe 14 and connected to the reaction tower 2 side from the opening / closing means 16 of the recovery pipe 15. The consolidation prevention gas supply means 9 supplies the gas from the consolidation prevention gas supply pipe 17 into the reaction tower 2 through the collection pipe 15 in a state where the collection pipe 15 is closed by the opening / closing means 16. To do. Further, by supplying the gas from the gas supply means 9 for preventing consolidation, the gas flows between the solid particles of magnesium ammonium phosphate accumulated at the bottom of the reaction tower 2, thereby preventing the solid particles from being consolidated.

  The outflow means 10 has an outflow trough 18 installed on the side surface of the reaction tower 2, and an outflow portion 20 connected to the outflow trough 18 and the outflow pipe 19. Then, the processed product from the reaction tower 2 passes through an overflow dam (not shown) provided in the outflow trough 18 and flows out of the reaction tower 2 from the outflow pipe 19 via the outflow portion 20.

  The reaction tower 2 has a cylindrical reaction tower straight body section 21, and a cylindrical reaction tower cone section 22 whose diameter is reduced downward is integrally connected to a lower portion of the reaction tower straight body section 21. ing. In addition, a cylindrical reaction tower precipitation cone portion 23 whose diameter is reduced toward the reaction tower straight body portion 21 is integrally connected to the upper portion of the reaction tower straight body portion 21. Further, a cylindrical reaction tower precipitation straight body portion 24 having an open top is integrally connected to the upper portion of the reaction tower precipitation cone portion 23.

  Such a reaction tower 2 includes the height of the reaction tower 2 (the total height of the reaction tower straight body 21, the reaction tower precipitation cone 23 and the reaction tower precipitation straight body 24) and the reaction tower straight body 21. It is preferable that the ratio to the diameter (height of the reaction tower 2 / diameter of the reaction tower straight body portion 21) is designed to be in the range of 2 to 7, more preferably in the range of 2.5 to 6. More preferably, it is in the range of 3 to 5.

  The reaction column body 21 has a larger diameter than the reaction tube 3, and the reaction tube 3 and the reaction column body 21 have a ratio between the diameter of the reaction tube 3 and the diameter of the reaction column body 21 ( The diameter of the reaction cylinder 3 / the diameter of the reaction tower straight body portion 21) is preferably designed to be in the range of 0.2 to 0.8, more preferably 0.3 to 0.7. It is a range, More preferably, it is the range of 0.4-0.6.

  The bottom of the reaction tower cone 22 is formed so that the side surface is reduced in diameter downward and the lower end, which is the tip, is closed. In the reaction tower cone 22, the solid particles of magnesium ammonium phosphate crystals are accumulated so as to descend along the side surface and gather at the bottom.

  The reaction tower precipitation cone 23 lowers the magnesium ammonium phosphate crystal that has been precipitated and separated from the reaction tower precipitation straight body 24 so as to rectify along the side surface.

  The inclination angle of the side surfaces of the reaction tower cone portion 22 and the reaction tower precipitation cone portion 23 may be any angle as long as the magnesium ammonium phosphate crystal is likely to descend along the side surface, and is preferably 45 degrees or more, for example, 60 degrees or more. Is more preferable.

  Here, a cylindrical first cylinder 31 such as a cylinder is provided in the reaction tower precipitation cone 23.

  The first cylinder 31 has a cylindrical cylinder body 32 having a diameter larger than that of the reaction cylinder 3 and substantially the same diameter as the reaction tower straight body portion 21. Further, a tapered portion 33 whose diameter is increased downward is integrally connected to the lower end of the cylindrical main body 32.

  The first cylindrical body 31 is arranged such that the lower end, that is, the tip of the tapered portion 33, is spaced apart from the reaction tower precipitation cone portion 23. A lower slit 34 is formed between the tapered portion 33 of the first cylindrical body 31 and the reaction tower precipitation cone portion 23 through which the workpiece and the magnesium ammonium phosphate crystal can pass.

  Above the first cylinder 31, a cylindrical second cylinder 35 such as a cylinder is provided apart from the first cylinder 31.

  The second cylinder 35 has a diameter larger than that of the reaction cylinder 3 and substantially the same diameter as the cylinder main body 32. The second cylinder 35 is connected to the lower end of the cylinder main body 36 and expands in diameter downward. A tapered portion 37 having a diameter larger than 32 and an upper surface portion 38 provided at the upper end of the cylinder main body 36 are provided.

  An upper slit 39 through which the workpiece and the magnesium ammonium phosphate crystal can pass is formed between the tapered portion 37 of the second cylinder 35 and the cylinder body 32 of the first cylinder 31. . The upper slit 39 is located below the reaction tower precipitation straight body portion 24.

  The angle of inclination of the tapered portion 33 and the tapered portion 37 is such that the angle of repose between the cylindrical main body 32 and the cylindrical main body 36 is such that the precipitated magnesium ammonium phosphate crystals are likely to fall along the tapered portion 33 and the tapered portion 37. It is preferably 45 degrees or less, and more preferably 30 degrees or less.

  The reaction tower precipitation straight body portion 24 has a gravity precipitation portion 41 formed between the inside of the reaction tower precipitation straight body portion 24 and the outside of the second cylinder 35. The gravity precipitation portion 41 is a portion that separates the processed product from which phosphorus has been removed and magnesium ammonium phosphate by the difference in specific gravity, and has at least one (for example, four) slopes that promote the precipitation separation effect. The plate 42 is provided so as to be positioned above the upper slit 39.

  The inclined plate 42 is inclined so that the lower side is located on the outer side, and the inclination angle is preferably 45 degrees or more and 70 degrees or less considering the ease of flow of the magnesium ammonium phosphate crystals and the effect of promoting precipitation separation. More preferably, it is 55 degrees or more and 65 degrees or less. Further, the installation interval of the inclined plates 42 is preferably 30 mm or more so as not to be blocked by sludge or the like as an object to be processed. Further, the inclined plate 42 is a height in which the axial height of the reaction tower precipitation straight body portion 24 is constituted by the adjacent inclined plates 42 (the installation interval of the inclined plates 42 is B, and the inclination angle is θ In this case, it is preferable to be at least twice B × tan θ).

  In the reaction tower 2, the reaction cylinder 3 is disposed from the reaction tower cone 22 through the first cylinder 31 to the second cylinder 35, and the upper end is located above the upper slit 39. The lower end portion is located below the reaction tower straight body portion 21.

  The reaction tower 2 and the reaction cylinder 3 have a length from the lower end portion of the reaction cylinder 3 to the boundary portion 43 between the reaction tower straight body portion 21 and the reaction tower cone portion 22, and from the boundary portion 43 to the reaction tower cone portion. The ratio of the length to the bottom of 22 (the length from the lower end of the reaction cylinder 3 to the boundary 43 / the length from the boundary 43 to the bottom of the reaction tower cone 22) is greater than 0 and 0.4 It is preferable to design so as to be in the following range, more preferably in the range of 0.05 to 0.3, and still more preferably in the range of 0.07 to 0.25.

In the reaction tower 2, the water area load of the gravity precipitation portion 41 is preferably in the range of 5 m ³ / m ² / day or more and 60 m ³ / m ² / day or less with respect to the supply amount of the object to be treated. Is in the range of 6 m ³ / m ² / day to 50 m ³ / m ² / day, more preferably in the range of 8 m ³ / m ² / day to 40 m ³ / m ² / day.

  Next, a method for removing and collecting phosphorus from the object to be processed by the phosphorus removing and collecting apparatus 1 will be described.

  When removing and recovering phosphorus from the object to be processed by the phosphorus removal and collection apparatus 1, first, the object to be processed is supplied from the object supply means 4 into the reaction cylinder 3, and the aeration gas supply means 7 and Gas is supplied from the gas supply means 9 for preventing consolidation into the reaction cylinder 3.

  Further, the magnesium compound is supplied from the magnesium compound supply means 5 into the reaction cylinder 3 while supplying the workpiece and the gas in this way.

  The supply amount of the object to be processed is a portion formed in the reaction tower straight body portion 21, a portion formed in the first cylindrical body 31, and a portion formed in the second cylindrical body 35. It is preferable to adjust the water retention time to be in the range of 5 minutes to 90 minutes, more preferably 10 minutes to 60 minutes, and still more preferably 15 minutes to 40 minutes.

The supply amount of the gas from the aeration gas supply means 7 and consolidation preventing gas supplying means 9, the horizontal direction of the cross-sectional area of the reaction tower straight barrel section 21, 5m 3 ^{/ m} 2 / Time least 100 m 3 ^/ m It is preferably adjusted to be in the range of ² / hr or less, more preferably in the range of less ^8m 3 / ^{m 2} / hour or more ^70m 3 / ^{m 2} / hour, more preferably ^{10 m} 3 / ^{m 2} / hr It is the range of 50 m ³ / m ² / hour or less. Note that the air volume ratio (aeration gas / anti-condensation gas) of the aeration gas supply means 7 and the anti-consolidation gas supply means 9 is preferably adjusted to be in the range of 3 to 20.

The magnesium compound to be added has a molar ratio ([Mg] / [PO ₄ -P]) of magnesium to a molar ratio of phosphate ions contained in the object to be processed in a range of 0.5 to 2.0. It is preferable to adjust, More preferably, it is the range of 0.7-1.5.

  When the magnesium compound is supplied into the reaction cylinder 3 to which the object to be processed is supplied in this way, the pH rises and becomes alkaline, resulting in an atmosphere in which the object to be processed and the magnesium compound easily react. In addition, when the alkalinity of the object to be processed is low and the pH does not increase sufficiently even when a magnesium compound is added, an alkaline agent is appropriately supplied from the alkaline agent supply means 6 to adjust the pH so that the reaction is easy. You may adjust.

  Further, by supplying the aeration gas into the reaction cylinder 3, an ascending airflow is generated in the reaction cylinder 3 and the object to be processed and the magnesium compound are aerated and agitated to promote the reaction.

  Here, even if the gas supplied from the aeration gas supply means 7 leaks to the outside of the reaction cylinder 3 and rises, for example, it is collected in the taper part 33 or the taper part 37, and the first cylinder 31 or Guided into the second cylinder 35.

  And in the reaction cylinder 3, a to-be-processed object and a magnesium compound react, stirring with the gas for aeration, and a magnesium ammonium phosphate crystal | crystallization is produced | generated.

  As described above, the magnesium ammonium phosphate crystal generated in the reaction cylinder 3 and the object to be processed in the reaction cylinder 3 are supplied from the lower end of the reaction cylinder 3 to the second cylinder by the ascending airflow due to the gas for aeration. Move to body 35.

  Here, in the vicinity of the lower end portion of the reaction cylinder 3, a negative pressure is generated because the object to be processed and the gas for aeration are blown up, and a downward flow is generated between the reaction cylinder 3 and the reaction tower cylinder 21. As a result, a circulating flow is generated in which the air is blown up by an ascending air flow due to the aeration gas.

  The gas for aeration from the reaction cylinder 3 is collected in the second cylinder 35 and discharged to the outside as it is, and the object to be treated and the magnesium ammonium phosphate crystals from the reaction cylinder 3 are circulated. Is returned to the lower end of the reaction cylinder 3.

  In addition, since the object to be processed is continuously supplied from the object supply means 4, an outflow destination is required, and the outflow destination in the reaction tower 2 is an outflow installed in the upper part of the reaction tower precipitation straight body portion 24. Mean 10 only. Therefore, a part of the workpiece and the magnesium ammonium phosphate crystal moving along the circulating flow flows out from the upper slit 39 which is an opening having a shallow water depth and rises toward the outflow means 10.

  The magnesium ammonium phosphate crystal and the material to be processed that have passed through the upper slit 39 and flowed into the reaction tower precipitation cone portion 23 are about to flow out toward the outflow means 10 corresponding to the flow rate of the supplied material to be processed. It flows to the gravity precipitation part 41 by the upward flow.

  Magnesium ammonium phosphate has a true specific gravity of 1.72, and in the gravity precipitation portion 41, magnesium ammonium phosphate crystals having a high specific gravity and an object to be processed pass through the inclined plate. When passing, the magnesium ammonium phosphate crystals are precipitated and separated through the inclined plate 42 due to the difference in specific gravity.

  The water retention time with respect to the supply amount of the object to be processed in the gravity precipitation portion 41 is preferably in the range of 5 minutes to 120 minutes, more preferably in the range of 10 minutes to 90 minutes, and still more preferably. It is 15 minutes or more and 60 minutes or less.

  The precipitated and separated magnesium ammonium phosphate crystal descends along the side surface of the reaction tower precipitation cone 23 and flows out to the reaction tower straight body 21 while being rectified through the lower slit 34.

  In addition, the magnesium ammonium phosphate crystal that has flowed into the reaction tower straight body 21 in this way is blown up again through the reaction cylinder 3 along the circulating flow toward the lower end of the reaction cylinder 3 and supplied. Reacting with the magnesium compound, magnesium ammonium phosphate is further precipitated on the crystal surface and granulated.

  The magnesium ammonium phosphate crystals that have been granulated in this way and flowed into the reaction tower cylinder 21 flow from the reaction tower cylinder 21 to the reaction tower cone 22, and descend along the side surface of the reaction tower cone 22. Then, it accumulates at the bottom of the reaction tower cone 22.

  Further, among the magnesium ammonium phosphate crystals that have flowed into the second cylinder 35 from the reaction cylinder 3, the crystals that have not passed through the upper slit 39 are directly between the reaction cylinder 3 and the first cylinder 31. And the reaction tower straight body part 21 is lowered and accumulated at the bottom of the reaction tower cone part 22.

  As described above, the magnesium ammonium phosphate crystal flows into the reaction tower 2 by aeration to grow into solid particles, and is finally accumulated at the bottom of the reaction tower cone portion 22.

  Then, in a predetermined cycle such as 2 days or more and 2 weeks or less, the collection tube 15 is opened by the opening / closing means 16, and the solid particles of magnesium ammonium phosphate crystals are discharged out of the reaction tower 2 and collected.

  The solid particles of magnesium ammonium phosphate crystals collected in this way can be effectively used as phosphate compounds such as fertilizer raw materials, culture soil, and auxiliary materials for soil improvement materials.

  On the other hand, the magnesium ammonium phosphate crystals are separated in the reaction tower precipitation straight body section 24, and the treated product after the phosphorus is removed flows out from the reaction tower precipitation straight body section 24 to the outflow section 20 through the outflow trough 18. Then, it is discharged out of the reaction tower 2 from the outflow pipe 19.

  Further, the processed product discharged from the reaction tower 2 is sent to a liquid cyclone or a gravity sedimentation tank to further improve the recovery rate of the solid particles of magnesium ammonium phosphate crystals, and then returned to the reaction tower 2 after collecting the fine particles. You may make it the structure to carry out.

  Next, the operation and effect of the one embodiment will be described.

  According to the one embodiment, since the inclined plate 42 is provided in the reaction tower precipitation straight body portion 24, the precipitation separation effect due to the difference in specific gravity in the gravity precipitation portion 41 can be improved, for example, relatively Even magnesium ammonium phosphate crystals having a small particle size can be separated by precipitation. Therefore, solid particles of magnesium ammonium phosphate crystals can be efficiently recovered.

  In particular, by setting the inclination angle of the inclined plate 42 to 45 degrees or more and 70 degrees or less, the precipitation separation effect in the gravity precipitation portion 41 can be improved.

  Further, since the first cylinder 31 has the taper portion 33 and the second cylinder 35 has the taper portion 37, the gas supplied from the aeration gas supply means leaks from the reaction cylinder 3 and the reaction cylinder. Even if the outside of the body 3 is raised, the gas can be collected by the taper portion 33 or the taper portion 37 and guided into the first cylinder body 31 and the second cylinder body 35, and above the taper section 37. The rise of gas to the can be prevented. Therefore, inhibition of precipitation separation in the reaction tower precipitation straight body portion 24 due to gas can be prevented, and solid particles of magnesium ammonium phosphate crystals can be efficiently recovered.

  In addition, since the upper end portion of the reaction cylinder 3 is located above the upper slit 39, the gas rising in the reaction cylinder 3 does not flow out of the upper slit 39, and is appropriately precipitated in the reaction tower precipitation straight body 24. Can be separated.

  Further, a gas supply means 9 for preventing consolidation is provided, and the aeration gas supply pipe 14 and the gas supply pipe 17 for consolidation prevention are separately provided, so that the tip of the gas supply pipe 14 for aeration is brought to a desired position. Since it can be installed, the aeration gas supply pipe 14 can be installed at an appropriate position so that the aeration gas can be easily supplied into the reaction cylinder 3 and the air lift action can be easily obtained. Therefore, the air lift action by the aeration gas can be improved, and the aeration gas is unlikely to leak to the outside of the reaction cylinder 3, and the precipitation separation can be prevented from being inhibited by the leaked gas.

  The aeration gas leaks from the reaction cylinder 3 by making the reaction tower straight body 21 and the cylinder body 32 of the first cylinder 31 and the cylinder body 36 of the second cylinder 35 substantially the same diameter. Even if it rises, the range of this gas diffusion can be controlled on the extension line of the reaction tower straight body part 21, and the taper part 33 and the taper part 37 can collect more reliably.

  In addition, when the sludge density | concentration of a to-be-processed object is about 1000 mg / L or lower than 1000 mg / L, even if it is the precipitation separation method in the conventional reaction tower, solid particles of a magnesium ammonium phosphate crystal | crystallization can be collect | recovered, but digested sludge When the sludge concentration exceeds about 10000 mg / L or 10000 mg / L, the viscosity increases, so that the gravity separation effect of solid particles of magnesium ammonium phosphate crystals is obtained by the precipitation separation method in the conventional reaction tower. Decreases. On the other hand, the digested sludge itself has a slow sedimentation rate, so there is no risk of accumulation due to sedimentation in the reaction tower 2. Therefore, in order to increase the precipitation effect in the reaction tower precipitation straight body part 24 which is the precipitation separation part, it is possible to prevent leakage of aeration gas, improve the rectification effect, and improve the precipitation effect by the inclined plate 42. This is effective in improving the recovery rate of magnesium ammonium.

  In the above embodiment, the reaction column 2 is provided with the alkali agent supply means 6. However, the alkali agent is added as necessary, and the alkali agent supply means 6 is not provided. May be.

  Further, the configuration is not limited to the configuration in which the four inclined plates 42 are provided, and the number of the inclined plates 42 can be appropriately selected.

  Hereinafter, this embodiment will be described.

  The diameter of the reaction tower straight body 21 is 300 mm, the diameter of the reaction tower precipitation straight body 24 is 600 mm, the reaction tower straight body 21, the reaction tower cone 22, the reaction tower precipitation cone 23, and the reaction tower precipitation straight The reaction tower 2 having a total height of 1500 mm including the body 24 and a total volume of 156 liters (L) is used, and a reaction cylinder 3 having a diameter of 150 mm is installed in the reaction tower 2 to constitute a phosphorus removal and recovery apparatus 1 did.

  In such a phosphorus removal and recovery apparatus 1, anaerobic digested sludge containing 290 mg / L of phosphorous phosphorus and 820 mg / L of ammonia nitrogen and having a pH of 7.4 to be treated is continuously supplied at a flow rate of 5000 L / day. Supplied to. Moreover, magnesium hydroxide as a magnesium compound was continuously supplied so that the magnesium addition molar ratio was 0.9 with respect to the number of moles of phosphate phosphorus in the anaerobic digested sludge. Further, air as aeration gas was continuously supplied at 50 L / min for aeration.

  Further, the treated sludge as the treated product flowing out from the outflow means 10 of the reaction tower 2 was passed through a liquid cyclone, and the recovery side was returned to the reaction tower 2.

  As a result of measuring the phosphate phosphorus concentration of the treated sludge flowing out from the outflow means 10, it was reduced to 32 mg / L.

  Further, the solid particles of magnesium ammonium phosphate crystals accumulated in the reaction tower cone 22 were collected once every 2 to 4 days.

  And about the collect | recovered solid particle of magnesium ammonium phosphate crystal, mass was measured, and the amount of phosphorus recovered was calculated, and the recovery rate with respect to the phosphate phosphorus removal amount in the recovery interval was calculated. As a result, the recovery rate was 90% Met.

DESCRIPTION OF SYMBOLS 1 Phosphorus removal collection apparatus 2 Reaction tower 3 Reaction cylinder 4 To-be-processed object supply means 5 Magnesium compound supply means 7 Aeration gas supply means 8 Solid particle collection means 9 Consolidation prevention gas supply means
10 Outflow means
14 Gas supply pipe for aeration
17 Gas supply pipe for preventing consolidation
21 Reaction tower straight body
22 Reaction tower cone
23 Reaction tower precipitation cone
24 Reactor column precipitation straight body
31 First cylinder
32 Tube body
33 Taper
34 Lower slit
35 Second cylinder
36 Tube body
37 Taper
39 Upper slit
42 Inclined plate

Claims (2)

A phosphorus removal and recovery device that reacts a processing object containing phosphate ions and ammonium ions with a magnesium compound and recovers phosphorus of the processing object as solid particles of magnesium ammonium phosphate crystals,
A reaction tower;
A cylindrical reaction cylinder provided inside the reaction tower;
An object supply means for supplying an object to be processed into the reaction cylinder;
A magnesium compound supply means for supplying a magnesium compound into the reaction cylinder;
Aeration gas supply means for supplying the aeration gas upward into the reaction cylinder;
An anti-consolidation gas supply means for supplying the anti-consolidation gas into the reaction tower;
Solid particle recovery means connected to the bottom of the reaction tower for recovering solid particles of magnesium ammonium phosphate crystals produced in the reaction tower;
An outflow means located at the upper part of the reaction tower and for outflowing the treated product from which phosphorus has been removed;
The reaction tower is
A cylindrical reaction tower straight body,
A cylindrical reaction tower conical section disposed at the bottom of the reaction tower straight body and having a bottom diameter reduced toward the bottom;
A cylindrical reaction tower precipitation cone disposed at an upper part of the reaction tower straight body and having a diameter reduced toward the reaction tower straight body;
A cylindrical reaction tower precipitation straight body part that is disposed at the upper part of the reaction tower precipitation cone part and precipitates and separates the treated product and the magnesium ammonium phosphate crystal,
This reaction tower sediment straight body is provided with at least one inclined plate inside,
A cylindrical first cylinder is provided in the reaction tower precipitation cone, and a cylindrical second cylinder is provided above the first cylinder.
The first cylinder and the second cylinder have a cylinder main body and a tapered portion that is connected to the lower end of the cylinder main body and has a diameter that increases downward.
A lower slit is formed between the tapered portion of the first cylindrical body and the side surface of the reaction tower precipitation cone portion, and between the tapered portion of the second cylindrical body and the cylindrical main body of the first cylindrical body. The upper slit is configured with
The upper slit is located below the reaction tower sediment straight body,
The reaction cylinder is arranged from the inside of the reaction tower cone to the second cylinder, the upper end portion is located above the upper slit, and the lower end portion is below the reaction tower straight body portion. Position to,
The aeration gas supply means has an aeration gas supply pipe whose tip is disposed below the reaction cylinder in the reaction tower,
The phosphorus removal and recovery apparatus, wherein the consolidation prevention gas supply means has a consolidation prevention gas supply pipe connected to the bottom of the reaction tower. A phosphorus removal and recovery method for reacting a treatment object containing phosphate ions and ammonium ions with a magnesium compound and recovering the phosphate ions of the treatment object as solid particles of magnesium ammonium phosphate,
The phosphorus removal and recovery apparatus according to claim 1 is used.

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