JP2007244995A - Treatment equipment of digestion sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide treatment equipment of digestion sludge capable of preventing scale deposition in a sludge-feeding pipe for feeding digestion sludge to a sludge treatment installation such as sludge fusion equipment by efficiently recovering soluble phosphate ions of high concentration, serving as a factor component for causing scaling, from the digestion sludge in a short time as solid particles of ammonium magnesium phosphate (MAP). <P>SOLUTION: The treatment equipment of digestion sludge comprises: a MAP reaction tower 3 provided with a digestion sludge injection pipe 4 for injecting the digestion sludge, a magnesium compound injection pipe 5, a gas blow pipe 6 for aeration, a MAP draw pipe 7 for drawing out the digestion sludge containing MAP particles and a treated sludge pipe 8 for discharging the treated digestion sludge; a MAP recovery device 9 which is connected to the treated sludge pipe 8, recovers fine MAP particles included in treated sludge and returns the recovered fine MAP particles to the MAP reaction tower 3; a liquid cyclone which is connected to the MAP draw pipe 7 of the MAP reaction tower 3 and concentrates the digestion sludge; and a screen which separates and removes the MAP particles from condensate fed from the liquid cyclone. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention removes soluble phosphate phosphorus from anaerobic digested sludge, recovers it as solid magnesium ammonium phosphate particles, and attaches the digested sludge to a sludge treatment facility such as a sludge melting facility. The present invention relates to an apparatus for treating digested sludge that can be prevented.

Conventionally, when sludge generated from a sewage treatment facility is sent to a sludge treatment facility such as a sludge melting facility, phosphate ions (PO ₄ ³⁻ ), magnesium ions (Mg ²⁺ ), ammonium ions contained in the sludge (NH ₄ ⁺ ) produces magnesium ammonium phosphate (MgNH ₄ PO ₄ .6H ₂ O; hereinafter referred to as MAP) in the pipe, phosphate ion (PO ₄ ³⁻ ), calcium ion (Ca ²⁺ ). Reacts to form calcium phosphate compounds and precipitates on the inner wall of the pipe to form a scale, gradually reducing the diameter of the mud pipe, and in the worst case, the mud pipe may eventually be blocked. there were.

  When the mud is sent after the volume of sludge is reduced by the anaerobic digester, the concentration of each ion forming MAP is high, and the above tendency increases. In particular, along with the advanced treatment of sewage treatment facilities in recent years, sludge to which biological dephosphorization is applied has a high phosphate ion concentration discharged by anaerobic digestion, and there is a possibility that clogging of the mud pipe may be accelerated. It was.

  As a method to prevent clogging of the mud pipe, conventionally, a large amount of iron or aluminum inorganic flocculant is added, and the phosphate ion concentration in the digested sludge is reduced below the saturation concentration of MAP production, and MAP production reaction However, this method requires a large amount of flocculant, and the addition of a large amount of metal salt can lead to the use of refractory materials in the subsequent sludge treatment facility, particularly the sludge melting facility. The impact was a concern.

  As a method for solving such a problem, an aeration apparatus is provided upstream of a pipeline for transporting sludge, the sludge is aerated in advance with this aeration apparatus, the pH is increased by decarboxylation, and components that cause MAP are generated. A removal method (for example, see Patent Document 1) is known. However, in the method described here, usually, the digested sludge contains moles of phosphate ions greater than the number of moles of magnesium ions, and the MAP reaction is an equivalent reaction of magnesium ions and phosphate ions. A considerable amount of acid ions are expected to remain, and since MAP is not collected, there is a possibility that MAP is re-dissolved in the piping and MAP is generated.

  A method of separating MAP particles generated in the above method with a centrifuge (for example, see Patent Document 2) is known. However, in this method as well, as described above, it is expected that a considerable amount of phosphate ions will remain because the magnesium ions previously contained in the digested sludge are used in the MAP reaction. In addition, although there is a description of a method for separating MAP particles before sending the mud, it is naturally expected that the digested sludge is mixed in a large amount from the centrifugal concentrate, and the purity of the MAP particles is further increased. There is no description of the separation method for improving

  Furthermore, a processing method and a processing apparatus (see, for example, Patent Document 3) are known in which a magnesium source is added to a digester and the generated MAP crystals are separated. However, in the method and apparatus described herein, adding a magnesium source directly into the digester may cause a MAP reaction in the digester and facilitate scaling of the MAP in the digester. . Once a failure due to scaling in the digester occurred, there was a major problem that the operation of the entire treatment facility was stopped.

  Furthermore, a processing method and a processing apparatus (for example, refer to Patent Document 4) including a digestion tank and a MAP ripening tank capable of adding a magnesium source at a subsequent stage are known. However, since the method and apparatus described here are a method and apparatus for returning a liquid containing fine MAP to the digester, there is a risk of causing MAP accumulation or scaling in the digester. It was.

  On the other hand, conventionally, a method and an apparatus (for example, refer to Patent Document 5) are known in which a magnesium compound is added to wastewater containing ammonium ions and phosphate ions, and the wastewater is stirred by aeration to generate MAP solid particles. Yes.

Furthermore, an apparatus that collects fine MAP particles with a liquid cyclone (for example, see Patent Document 6) and an apparatus that efficiently collects generated MAP solid particles with a screen (for example, see Patent Document 7) are known. However, the devices described in these documents are intended for wastewater having a sludge concentration of several thousand mg / L or less, such as digested sludge dehydrated filtrate and human urine effluent, and sludge having a sludge concentration of about tens of thousands mg / L. There was no knowledge about the collection and separation of MAP at high sludge concentration.
JP 2000-271595 A JP 2001-162300 A Japanese Patent Laid-Open No. 2004-941 JP 2004-160300 A Japanese Patent No. 2578136 Japanese Patent No. 3681073 JP-A-9-117774

  The present invention recovers digested sludge from sludge treatment equipment such as sludge melting equipment by efficiently recovering high-concentration soluble phosphate ions, which are components that cause scaling, as solid particles of MAP in a short time. It is intended to provide a technology that can prevent the scale from adhering to the mud pipe sent to the facility.

  As a result of intensive studies to solve such problems, the present inventor can efficiently remove phosphate ions contained in the digested sludge in a short time by using the digested sludge treatment apparatus constituted by a specific apparatus. The present inventors have found the fact that they can be recovered as MAP solid particles with little sludge contamination, and have reached the present invention.

  That is, the present invention is a digested sludge injection tube for injecting digested sludge, a magnesium compound injection tube, a gas blowing tube for aeration, a extraction tube for extracting digested sludge containing magnesium ammonium phosphate particles, and a treatment A reaction tower equipped with a treated sludge pipe for discharging digested sludge, and a collection connected to the treated sludge pipe for collecting fine magnesium ammonium phosphate particles contained in the treated sludge and returning them to the reaction tower Connected to the apparatus and the extraction tube of the reaction tower, liquid cyclone for concentrating digested sludge containing magnesium ammonium phosphate particles, and separation and removal of magnesium ammonium phosphate particles from the concentrated solution from this liquid cyclone A digested sludge treatment apparatus characterized by comprising a screen that performs the above process.

  As described above, according to the present invention, high-concentration phosphate ions, which are scaling factors such as MAP, can be efficiently and quickly recovered from the digested sludge as MAP solid particles. It is possible to prevent the scale from adhering to the sludge pipe sent to the sludge treatment facility. Furthermore, phosphorus resources that are depleted resources can be recovered, and can be effectively used as a slow-acting chemical fertilizer that maintains the fertilization effect.

Embodiments of the present invention will be specifically described below with reference to the drawings.
The digested sludge to be used in the present invention contains phosphate ions and ammonium ions, and those containing a high concentration of phosphate ions are particularly suitable. A typical example of such digested sludge is applied to reduce and stabilize the initial sedimentation basin sludge (raw sludge) and / or final sedimentation basin sludge (excess sludge) generated from a sewage treatment facility. Examples include digested sludge (anaerobic digested sludge) extracted from an anaerobic digester.

Next, the digested sludge treatment apparatus of the present invention will be described with reference to the flow sheet of FIG.
Digested sludge extracted from the anaerobic digester 1 is supplied to the treatment apparatus 2 of the present invention. The processing apparatus 2 has a MAP reaction tower 3 for generating MAP. In the MAP reaction tower 3, a digested sludge injection pipe 4 for injecting digested sludge, and a magnesium compound injection for supplying a magnesium compound are provided. A pipe 5, a gas blowing pipe 6 for aeration, a MAP extraction pipe 7 for extracting MAP solid particles and digested sludge, and a treated sludge pipe 8 are provided. Furthermore, it has a MAP recovery device 9 for recovering fine MAP solid particles flowing out from the MAP reaction tower 3, and the fine MAP solid particles recovered by the MAP recovery device 9 are recovered in the MAP reaction tower 3. It is returned by the MAP return pipe 10. Further, a separation device 11 for separating the MAP solid particles from the mixture of the MAP solid particles and the digested sludge drawn from the MAP reaction tower 3 through the MAP drawing tube 7 is provided. The digested sludge and fine MAP solid particles are returned to the MAP reaction tower 3 via the separated sludge return pipe 12. In the present invention, the separation device 11 includes a liquid cyclone for concentrating the mixture and a screen for separating MAP from the concentrated mixture. In FIG. 1, reference numeral 13 denotes a hydrocyclone-treated sludge pipe connecting the MAP recovery device 9 and the next sludge treatment step 14, and 15 denotes separated MAP particles removed from the separation device 11.

Next, details of the MAP reaction tower 3, the MAP recovery device 9, and the separation device 11 constituting the processing device 2 will be described.
In the MAP reaction tower 3, by adding a magnesium compound that is deficient in an amount equivalent to phosphate ions to phosphate ions and ammonium ions contained in a large amount in the digested sludge, the MAP reaction formula (1) is used to express MAP. To grow into solid particles.
PO ₄ ³⁻ + NH ₄ ⁺ + Mg ²⁺ + 6H ₂ O → MgNH ₄ PO ₄ .6H ₂ O ↓ (MAP) (1)
In the reaction of formula (1), the higher the pH, the more the chemical equilibrium reaction moves to the right side, and the phosphorous phosphorus concentration in the digested sludge decreases, so the pH in the MAP reaction tower 3 can be adjusted with an alkaline agent such as caustic soda. Although it may be performed, usually, carbonation in the digested sludge is expelled by aeration, and as a result the pH rises, so pH adjustment is not necessarily required. The optimum pH of the formula (1) is usually preferably in the range of 7.0 to 9.5, more preferably in the range of 7.5 to 9.0, and 8.0 to 8.5. The range of is most preferable.

  The magnesium compound to be added is not particularly limited as long as it is a compound containing magnesium such as magnesium chloride and magnesium hydroxide, but it is an alkali agent itself, and inexpensive magnesium hydroxide is preferably used. The rate of addition depends on the concentration of magnesium ions contained in the digested sludge, but usually, the number of moles of magnesium is 0.8-2 with respect to the number of soluble phosphate phosphorus in the digested sludge. It is preferable to add the magnesium compound so as to be 5 times, more preferably 0.9 to 2.0 times, and most preferably 1.0 to 1.5 times.

  In the MAP reaction tower 3, the inside of the MAP reaction tower 3 needs to be stirred and mixed in order to advance the chemical reaction of the formula (1). The stirring method is not particularly limited, such as a mechanical stirring method by rotation of a stirring blade or a circulating mixing method by a pump in the MAP reaction tower 3, but as described above, considering the decarboxylation effect and reaction efficiency. An air stirred vertical double cylindrical reactor is most suitable.

Next, an air stirring type vertical double cylindrical reactor will be described with reference to FIG.
The MAP reaction tower 3 includes a MAP reaction tower straight body section 16, a MAP reaction tower cone section 17 positioned below the MAP reaction tower straight section 16, and a diameter larger than the MAP reaction tower straight body section 16 located above the MAP reaction tower straight body section 16. The MAP reaction column cylindrical body 19 is formed so that a slit is formed in the MAP reaction column precipitation unit 18 at the intersection of the inclined portion and the MAP reaction column straight body 16. Further, the MAP reaction tower second cylindrical body 20 is erected inside.

  The inclination angle of the MAP reaction tower sedimentation section 18 and the inclination angle of the MAP reaction tower cone section 17 are not particularly limited, but in consideration of smooth sliding of solid particles, an inclination angle of 45 degrees or more is preferable. 60 degrees or more is preferable.

  The ratio of the diameter of the MAP reaction tower second cylinder 20 to the diameter of the MAP reaction tower straight body 16 (second cylinder diameter / MAP reaction tower straight body diameter) is usually 0.2 to 0. 0. It is preferably designed to be in the range of 8, more preferably in the range of 0.3 to 0.7, and most preferably in the range of 0.4 to 0.6.

  The ratio of the height of the MAP reaction tower 3 (the height of the MAP reaction tower straight body section 16 + the height of the MAP reaction tower sedimentation section 18) and the diameter of the MAP reaction tower straight body section 16 (MAP reaction tower height / MAP reaction tower) The diameter of the straight body part) is usually preferably designed to be in the range of 2-7, more preferably in the range of 2.5-6, and most preferably in the range of 3-5.

  In the present invention, the digested sludge is supplied to the inside of the second cylindrical body 20 of the MAP reaction tower through the digested sludge injection pipe 4. As the digested sludge supply amount, the sludge residence time in the MAP reaction tower reaction part volume (volume of the part formed by the MAP reaction tower straight body part 16 + volume of the part formed by the MAP reaction tower cylindrical body 19) is usually It is preferably set in the range of 5 to 90 minutes, more preferably in the range of 10 to 60 minutes, and most preferably in the range of 15 to 40 minutes.

The water area load of the gravity sedimentation portion of the solid particles formed inside the MAP reaction tower sedimentation section 18 and outside the MAP reaction tower cylinder 19 is usually 5 to 60 m ³ / m ² / day with respect to the digested sludge injection amount. , Preferably 6 to 50 m ³ / m ² / day, and more preferably 8 to 40 m ³ / m ² / day.

The aeration gas is blown into the MAP reaction tower 3 from the gas blowing pipe 6. The aeration gas is not particularly limited as long as it has a low carbon dioxide content, but air is usually used. The amount of air supplied from the gas blowing pipe 6 is usually in the range of 5 to 100 m ³ / m ² / hour, preferably 8 to 70 m ³ / m ² / hour, with respect to the cross-sectional area of the MAP reaction tower straight body portion 16. More preferably, the range is 10 to 50 m ³ / m ² / hour.

  In the MAP reaction tower 3, MAP crystals are generated and grown to form solid particles. The MAP solid particles are settled and separated by the MAP reaction tower sedimentation section 18, and the separated and separated MAP is formed by the intersection of the inclined portion of the MAP reaction tower sedimentation section 18 and the MAP reaction tower straight body section 16 and the MAP reaction tower cylinder 19. Slide into the MAP reaction tower 3 through the slit formed between them.

  On the other hand, MAP that did not settle and digested sludge with reduced phosphoric phosphorus concentration overflow the V-notch installed in the outflow trough surrounding the outside of the MAP reaction tower sedimentation section 18, and the MAP recovery device from the treated sludge pipe 8 9 is supplied.

  The MAP particles and digested sludge accumulated inside the MAP reaction tower 3 open the MAP extraction valve 21 connected to the bottom of the MAP reaction tower cone 17 via the gas blowing pipe 6 at intervals of 3 days to 2 weeks, It is supplied from the drawing tube 7 to the separation device 11.

The MAP reaction tower 3 may be filled with MAP seed crystals, and in that case, MAP particles having a large particle size can be obtained within a few days.
The MAP recovery device 9 recovers MAP particles from a mixture of digested sludge and fine MAP particles, and is not particularly limited, such as a screen separation method or a centrifugal separation method, but digested sludge and MAP particles ( A hydrocyclone utilizing a specific gravity difference of true specific gravity 1.72) is most suitable.

  The treated sludge pipe 8 is connected to the hydrocyclone relay tank 22, temporarily stored, and supplied by the hydrocyclone raw sludge supply pump 23 in the direction of the straight body portion of the hydrocyclone 24A. When the pressure on the upstream side of the hydrocyclone 24A is sufficiently high, the hydrocyclone relay tank 22 and the liquid cyclone raw sludge supply pump 23 are not necessary, but in order to obtain a sufficient supply speed, the hydrocyclone 24A is usually used. Considering the pressure loss, pumping by a pump is required.

  The supply amount to the liquid cyclone 24A is such that the liquid cyclone inlet flow velocity is usually in the range of 1 to 20 m / sec, preferably 2 to 10 m / sec, more preferably 3 to 8 m / sec. The mixture of digested sludge and fine MAP particles supplied to the hydrocyclone 24A becomes a rotational flow along the peripheral wall of the straight body portion of the hydrocyclone 24A and is given a shearing force accompanying a velocity gradient, and the cone at the bottom of the hydrocyclone 24A. The MAP particles having a large specific gravity reach the bottom and are returned to the MAP reaction tower 3 by the recovery MAP return pump 25 via the recovery MAP return pipe 26. The return amount is usually in the range of 1 to 30%, preferably 2 to 20%, more preferably 3 to 10% with respect to the supply amount to the hydrocyclone 24A. On the other hand, the digested sludge from which most of the MAP particles have been recovered rises in a vortex state near the center of the liquid cyclone 24A, and the next process of sludge treatment from the liquid cyclone-treated sludge pipe 13 connected to the upper part of the liquid cyclone 24A. 14 is transferred.

  Separation apparatus 11 separates MAP particles from a mixture of digested sludge and MAP particles extracted from the inside of MAP reaction tower 3, and includes a gravity sedimentation method and a centrifugal separation method using a specific gravity difference. The method of separating with a screen having a mesh width is most suitable.

  The MAP particles and the digested sludge accumulated in the MAP reaction tower 3 are supplied to the MAP separator 28 by the MAP extraction pump 27 connected to the MAP extraction pipe 7. The MAP separator 28 is composed of a screen, and the specified mesh width is usually in the range of 0.1 to 2 mm, preferably 0.15 to 1.5 mm, more preferably 0.2 to 1.0 mm. . A screen composed of a wedge wire having a trapezoidal cross section is effective in preventing clogging, and the screen may be either flat or cylindrical. A so-called trommel-shaped one in which the mixture to be separated is further supplied, the cylindrical body is rotated about 10 to 60 revolutions per minute, and washed with washing water is most suitable.

  The separated MAP particles 15 separated by the separation device 11 are discharged from one end of the MAP separator 28. On the other hand, the digested sludge and fine MAP particles that have passed through the screen are returned to the MAP reaction tower 3 by the separated sludge transfer pump 29.

  By supplying the MAP separator 28 after concentrating in advance as the separator 11, it is possible to prevent contamination with relatively small specific gravity in the separated MAP particles 15, and to reduce the amount of washing water. Separation is possible. As a method of concentration, there are a gravity sedimentation method, a centrifugal separation method, and the like, but the method of concentrating with the liquid cyclone 24B similar to the liquid cyclone 24A and supplying to the MAP separator 28 with the concentrated MAP supply pump 30 is the most. Suitable.

  The MAP extraction pipe 7 is connected to the MAP extraction pump 27 and supplied in the direction of the straight barrel section of the hydrocyclone 24B. The supply amount to the hydrocyclone 24B is such that the liquid cyclone inlet flow velocity is usually in the range of 1 to 20 m / sec, preferably 2 to 10 m / sec, more preferably 3 to 8 m / sec. The mixture of digested sludge and MAP particles supplied to the hydrocyclone 24B becomes a rotational flow along the peripheral wall of the straight cylinder portion of the hydrocyclone 24B, and is given a shearing force accompanying a velocity gradient, to the lower cone of the hydrocyclone 24B. The MAP particles having a large specific gravity reach the bottom and are supplied to the MAP separator 28 by the concentrated MAP supply pump 30. The supply amount is usually in the range of 1 to 30%, preferably 2 to 20%, more preferably 3 to 10% with respect to the supply amount to the hydrocyclone 24B. On the other hand, the digested sludge from which most of the MAP particles have been recovered rises in a vortex state near the center of the cyclone and is returned to the MAP reaction tower 3 from the digested sludge return pipe 31 connected to the upper part of the liquid cyclone 24B.

The MAP separator 28 uses the screen described above, and the digested sludge and fine MAP particles that have passed through the screen are returned to the MAP reaction tower 3 by the separated sludge transfer pump 29.
With the above equipment, without adding a magnesium source to the digestion tank, scaling failure in the digestion tank is prevented, and phosphate ions in the digested sludge are removed sufficiently, and at the same time, it is effectively used as a slow-release chemical fertilizer It can be recovered as a possible form of MAP solid particles.

Next, the present invention will be specifically described with reference to examples.
Example 1
The diameter of the straight body part of the MAP reaction tower is 300 mm, the diameter of the sedimentation part is 600 mm, the total height of the straight body part, the sedimentation part and the lower cone part is 1510 mm, and the total volume is 160 liters. PH 7.8 is installed in a MAP reaction tower in which a cylindrical body is installed so as to form a slit at the intersection with the inclined portion of the precipitation section, and a second cylindrical body having a diameter of 155 mm is installed so that the upper end is located above the slit. Digested sludge containing phosphate phosphorus concentration of 150 mg / liter, sludge concentration of 26000 mg / liter and ammoniacal nitrogen concentration of 1000 mg / liter is continuously supplied at a flow rate of 5 m ³ / day, and 40 liter / min from the bottom of the MAP reaction tower. And 5% magnesium hydroxide so that the molar ratio is 1.5 with respect to the phosphate phosphorus concentration of 150 mg / liter. It was continuously fed the rally.

A mixture of digested sludge and fine MAP particles overflowed from the precipitation part of the MAP reaction tower was stored in a liquid cyclone relay tank having an effective capacity of 520 liters, and constantly stirred at a speed of 120 revolutions per minute by this liquid cyclone relay tank. The hydrocyclone raw sludge supply pump is activated by a level switch installed in the hydrocyclone relay tank, and the cutting speed is 6 at a flow rate of 120 m ³ / day at a recovery hydrocyclone with a straight body diameter of 115 mm and a conical part total height of 550 mm. Supplied at 8 m / sec. The digested sludge containing a large amount of fine MAP particles recovered by the liquid cyclone was continuously returned to the MAP reaction tower at a flow rate of 6 m ³ / day by a MAP return pump.

The above operation is continued for one week, and the MAP particles and digested sludge inside the reaction tower are flown from the lower part of the MAP reaction tower at a flow rate of 120 m ³ / day with a flow rate of 120 m ³ / day, the straight body diameter is 115 mm, and the total height is 550 mm. The liquid cyclone for concentration was supplied at a cutting speed of 6.8 m / sec. Digested sludge containing a large amount of MAP particles concentrated by a hydrocyclone is continuously connected to a drum type wedge wire screen with an inner diameter of 200 mm, a length of 600 mm, and an opening of 0.3 mm at a flow rate of 2 m ³ / day by a concentrated MAP supply pump. , Rotating at a speed of 10 revolutions per minute, and continuously washing with 4 m ³ / day of washing water. Fine MAP particles passing through the screen, digested sludge and washing water are separated by a separated sludge transfer pump. Returned to the MAP reaction tower. On the other hand, the digested sludge that flowed out from the top of the liquid cyclone was returned to the MAP reaction tower.

By the above method, the treatment sludge of the recovery liquid cyclone was raised to about pH 8.3, and the phosphate phosphorus concentration was lowered to 20 mg / liter or less. The MAP separation screen yielded solid particles of 0.3 mm or more, and as a result of X-ray diffraction, it was found to be MAP (magnesium ammonium phosphate; MgNH ₄ PO ₄ .6H ₂ O). As a result of component analysis after vacuum drying, it contains 28% soluble phosphoric acid (P ₂ O ₅ ), 15% soluble bitter earth (MgO), 5.4% ammoniacal nitrogen (NH ₄ -N), It has been found that the content of harmful components such as cadmium, mercury, lead, etc. is far below the allowable values of chemical components for chemical fertilizers stipulated in the Fertilizer Control Law.
Comparative Example 1
The same digested sludge used in Example 1 was treated with a MAP reaction tower similar to the above, and the fine MAP particles that flowed out by the liquid cyclone were recovered, and the mixture of MAP particles and digested sludge extracted from the bottom of the MAP reaction tower. Is continuously supplied to a drum-type wedge wire screen having an inner diameter of 200 mm, a length of 600 mm, and an opening of 0.3 mm at a flow rate of 2 m ³ / day without being concentrated by a hydrocyclone, and rotated at a speed of 10 rotations per minute. When washed continuously with 4 m ³ / day of wash water, the phosphate phosphorus concentration in the sludge treated with the MAP reaction tower decreased to 20 mg / liter or less, but a large amount was present in the MAP particles separated by the screen. Of impurities.

It is a flowchart which shows the processing apparatus of the digested sludge of this invention. It is the schematic which shows an example of the processing apparatus of the digested sludge of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anaerobic digestion tank 2 Processing apparatus 3 MAP reaction tower 4 Digested sludge injection pipe 5 Magnesium compound injection pipe 6 Gas blowing pipe 7 MAP extraction pipe 8 Processed sludge pipe 9 MAP recovery apparatus 10 Recovery MAP return pipe 11 Separation apparatus 12 Separation sludge return Tube 13 Hydrocyclone-treated sludge tube 14 Next step 15 Separated MAP particles 16 MAP reaction tower straight body part 17 MAP reaction tower cone part 18 MAP reaction tower sedimentation part 19 MAP reaction tower cylinder 20 MAP reaction tower second cylinder 21 MAP extraction Valve 22 Hydrocyclone relay tank 23 Liquid cyclone raw sludge supply pump 24A Liquid cyclone 24B Liquid cyclone 25 Recovery MAP return pump 26 Recovery MAP return pipe 27 MAP extraction pump 28 MAP separator 29 Separation sludge transfer pump 30 Concentrated MAP supply pump 31 Digested sludge Return tube

Claims (1)

Digested sludge injection pipe for injecting digested sludge, magnesium compound injection pipe, gas blowing pipe for aeration, extraction pipe for extracting digested sludge containing magnesium ammonium phosphate particles, and for discharging treated digested sludge A reaction tower provided with a treated sludge pipe, a recovery device connected to the treated sludge pipe, for recovering fine magnesium ammonium phosphate particles contained in the treated sludge and returning it to the reaction tower, and the reaction tower A liquid cyclone for concentrating digested sludge containing magnesium ammonium phosphate particles, and a screen for separating and removing magnesium ammonium phosphate particles from the concentrate from this liquid cyclone Digested sludge treatment equipment characterized by

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