JP4920017B2 - Control device and control method of phosphorus recovery device by crystallization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control apparatus and a control method in a phosphorous recovery device by crystallization, with which the improvement of efficiency of recovering phosphoric acid is made possible by calculating a phosphoric acid content in surplus sludge, finding a phosphoric acid release rate from the phosphoric acid content and controlling an organic matter injection amount so that phosphoric acid release can be made the maximum. <P>SOLUTION: The control apparatus comprises: a phosphoric acid content calculating means 200 where a phosphoric acid content in surplus sludge is calculated from data measured by a water quality measuring instrument installed in an activated sludge process; a phosphoric acid release rate calculating means 11 where a phosphoric acid release rate in a precipitation tank is calculated from measured data including the phosphoric acid content calculated by the phosphoric acid calculating means 200 and surplus sludge concentration measured by a surplus sludge densitometer, and concentration of organic matter necessary for the release of phosphoric acid is calculated from the calculated phosphoric acid release rate; and an organic matter injection controlling means 13 controlling the injection amount of an organic matter injection machine 12 injecting organic matter into the precipitation tank so as to attain the concentration of organic matter calculated by the phosphoric acid release rate calculating means 11. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  In the present invention, an organic substance is injected into surplus sludge of an activated sludge process and allowed to settle and settle in a sedimentation tank. The present invention relates to a control apparatus and control method for a recovery apparatus.

  Phosphorus is an essential nutrient for animals and plants, but the reserves of phosphate ore on the earth are limited and are expected to be depleted in 100 years. Therefore, the recovery and reuse of phosphorus has become an important issue.

  Since sewage through which animal and vegetable domestic wastewater flows contains low concentrations of phosphorus, research and experiments on technology to recover phosphorus from excess sludge and wastewater discharged from the activated sludge process at sewage treatment plants are underway. It has been.

  Since the recovered calcium phosphate can be used in various industries besides fertilizers, food additives, and reagents, it is insoluble by adding calcium (Ca) to soluble phosphoric acid (PO4-P). Various attempts have been made with respect to a method for recovering calcium phosphate (hereinafter, crystallization phosphorus recovery method).

  For example, in the anaerobic aerobic method, which is one of the activated sludge processes, soluble phosphorus contained in the inflowing sewage is stored as polyphosphoric acid in a microorganism group called activated sludge and removed from the sewage. . Therefore, the excess sludge extracted from the activated sludge process is settled in a sedimentation tank and separated into solid and liquid, and calcium phosphate is recovered by adding calcium to the supernatant of the sedimentation tank from which the excess sludge has been released. be able to. In such a crystallization phosphorus recovery method using surplus sludge, an appropriate operation of a process of sufficiently releasing phosphoric acid from the surplus sludge and a process of adding calcium corresponding to the amount of phosphoric acid is indispensable.

  Conventional techniques for recovering calcium phosphate from surplus sludge include biological digestion of at least a portion of surplus sludge discharged from a biological treatment apparatus for organic waste liquid as described in [Patent Document 1]. A surplus sludge treatment means for solubilizing digested sludge, a solid-liquid separation means for separating the liquid content of the surplus sludge treatment means, and a dephosphorization means for dephosphorizing the separated water from the solid-liquid separation means. An organic waste liquid treatment apparatus having a return means for returning a part of the treated water from the phosphorus means to the surplus sludge treatment means has been proposed.

  In addition, as described in [Patent Document 2], a conventional technique for controlling calcium injected into phosphorus-containing wastewater introduces phosphorus-containing wastewater into a reaction crystallization tank, and at least one of a calcium compound and an alkali agent is introduced. The phosphorus in the phosphate-containing wastewater is brought into contact with the crystal seeds while forming a fluidized bed of crystal seeds containing calcium phosphate, and the phosphorus in the phosphate-containing wastewater is separated as a calcium phosphate compound. Then, a crystallization dephosphorization method is proposed in which feedforward control is performed on at least one of a calcium compound and an alkali agent injected into the reaction crystallization tank in accordance with the flow rate of the phosphorus-containing wastewater introduced into the reaction crystallization tank. ing.

JP 2007-50387 A JP 2003-190967 A

  The amount of phosphoric acid in the influent sewage is affected by human social activities and industrial activities, and also fluctuates greatly under the influence of the natural world such as time, weather, season, etc., so excess sludge discharged from the activated sludge process The phosphoric acid content in it also varies. For this reason, the amount of phosphoric acid released when the excess sludge stays in the settling tank is not constant, and the rate of phosphoric acid released from the settling tank depends on the phosphoric acid content in the excess sludge, the excess sludge concentration, and the organic matter concentration in the liquid. It depends heavily.

  Therefore, in order to recover phosphoric acid from surplus sludge with high efficiency by the crystallization method, as described above, the phosphoric acid content in the surplus sludge that flows in is grasped, and organic substances are injected appropriately to appropriately add phosphoric acid. It is necessary to carry out the operation to be discharged.

  In the organic waste liquid treatment apparatus described in [Patent Document 1], there is no description about means for releasing phosphoric acid from excess sludge, and it cannot be applied to operation management of an apparatus for recovering phosphoric acid from excess sludge. Further, there is no description about a calcium injection method for phosphate fluctuation.

  On the other hand, [Patent Document 2] proposes a method for feedforward control of the amount of calcium injected according to the flow rate of phosphorus-containing waste water. However, in the crystallization and dephosphorization method described in [Patent Document 2], since control is performed according to the flow rate of the phosphorus-containing wastewater, when the amount of phosphoric acid varies, an appropriate calcium commensurate with the amount of phosphoric acid. There is a problem that can not be injected.

  For this reason, the phosphorus recovery rate decreases due to insufficient calcium injection, and conversely, residual calcium drainage due to excessive calcium injection is unavoidable. In particular, the calcium remaining in the wastewater not only has an adverse effect on the phosphorus recovery device, valve, and piping, but also has a significant adverse effect on the water environment.

  Thus, in the conventional techniques described in [Patent Document 1] and [Patent Document 2], in order to recover phosphorus from excess sludge, despite the importance of phosphoric acid release and calcium injection optimization, Since nothing is supported, there is a problem that an apparatus for recovering phosphoric acid from excess sludge cannot be properly operated.

  With respect to phosphoric acid measurement, a sensor that has automated a method of measuring sludge after membrane separation is being put into practical use for soluble phosphoric acid. However, the amount of phosphoric acid contained in excess sludge must be measured manually by measuring the phosphorus component using an element analyzer after drying the excess sludge. It was impossible to reflect the operation of the operating phosphorus recovery system.

  Thus, in order to stabilize the phosphorus recovery efficiency at a high level, it is necessary to inject an appropriate organic substance so as to maximize the phosphoric acid released from the excess sludge and to inject an appropriate calcium corresponding to the released phosphoric acid. However, there is a problem that it cannot be realized by the conventional technology.

  The object of the present invention is to calculate the phosphoric acid content of excess sludge, obtain the phosphoric acid release rate from the phosphoric acid content, and control the amount of organic matter injected so that the phosphoric acid release is maximized. It is an object of the present invention to provide a control device and a control method for a phosphorus recovery device by crystallization that can improve recovery efficiency.

  In order to achieve the above object, the present invention provides a phosphorus recovery apparatus in which surplus sludge from an activated sludge process is settled and retained in a settling tank, the supernatant liquid is guided to a crystallization tank, and calcium is added and recovered as calcium phosphate. In order to control the amount of phosphoric acid in the excess sludge, the phosphoric acid content calculating means for calculating the phosphoric acid content, the phosphoric acid releasing speed calculating means for calculating the phosphoric acid releasing speed, and the amount of organic substances injected into the precipitation tank are controlled. An organic substance injection control means and a calcium injection control means for controlling the amount of calcium injected into the crystallization tank, and the phosphoric acid release rate calculating means is based on the phosphoric acid content calculated by the phosphoric acid content calculating means. An organic material injection amount set value is calculated, and the organic material amount injected into the precipitation tank is controlled by the organic material injection control means based on the calculation result.

  The phosphoric acid release rate calculating means calculates the phosphoric acid release concentration based on the phosphoric acid content calculated by the phosphoric acid content calculating means, and based on the calculated phosphoric acid concentration, the calcium injection control means calculates calcium. The amount to be injected is controlled.

  According to the present invention, even if fluctuations in phosphoric acid stored in excess sludge and fluctuations in phosphoric acid flowing into the crystallization tank occur, it is appropriate to maximize the phosphoric acid released from the excess sludge. Organic matter can be injected, phosphorus recovery efficiency is stable and phosphorus can be recovered with high efficiency.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a phosphorus recovery apparatus using crystallization according to the present embodiment.

  An excess sludge concentration meter 2, a flow meter 20, and an inflow adjustment gate 3 are sequentially connected to the flow path 1 into which surplus sludge discharged from the activated sludge process shown as an example in FIG. A sedimentation tank 4 is connected by a path 6. A flow path 7 for extracting concentrated sludge is connected to the settling tank 4. The sedimentation tank 4 is connected to the crystallization tank 5 by a flow path 15 provided with a flow meter 9. The crystallization tank 5 is connected with a flow path 16 for draining and a flow path 8 for collecting calcium phosphate.

  The surplus sludge concentration meter 2 is connected to the phosphoric acid release rate calculating means 11 connected to the phosphoric acid content calculating means 200, and the phosphoric acid release rate calculating means 11 receives a signal from the flow meter 20 and inputs an organic substance injection machine. 12 is connected to organic injection control means 13 for outputting a control signal to 12 and calcium injection control means 14 for inputting a signal from the flow meter 9 and outputting a control signal to the calcium injector 10. The calcium injector 10 injects calcium into the crystallization tank 5.

  Excess sludge discharged from the activated sludge process and flowing through the flow path 1 flows into the settling tank 4. The surplus sludge flows into the settling tank 4 and settles, and is separated into concentrated surplus sludge and a supernatant liquid that does not contain sludge. When an organic substance is added to the precipitation tank 4 by the organic substance injection machine 12 and the inside of the precipitation tank 4 is maintained in an anaerobic state without oxygen, phosphoric acid stored by microorganisms in excess sludge is released into the liquid. The released phosphoric acid is dissolved in the supernatant liquid that is solid-liquid separated by retaining the excess sludge in the settling tank 4.

  The excess sludge that has settled in the settling tank 4 is drawn out from the settling tank 4 as a concentrated sludge by the flow path 7 and disposed. Extraction of the concentrated sludge may be performed continuously in a constant amount or intermittently. The amount of excess sludge that has flowed in is calculated, and the amount of concentrated sludge withdrawn is determined based on the calculated amount of solid matter.

  The supernatant liquid flowing out of the precipitation tank 4 is sent to the crystallization tank 5 through the flow path 15 and mixed with calcium injected from the calcium injector 10 to generate calcium phosphate. The calcium phosphate produced in the crystallization tank 5 is collected from the crystallization tank 5 continuously or intermittently by the flow path 8.

  The phosphoric acid content calculating means 200 calculates the phosphoric acid content stored in the surplus sludge from the data measured by the water quality measuring instrument installed in the activated sludge process of the sewage treatment plant, It transmits to the acid release rate calculation means 11.

  The phosphoric acid release rate calculating means 11 is used to calculate measurement data such as the excess sludge concentration measured by the excess sludge concentration meter 2, the excess sludge flow rate measured by the excess sludge flow meter 20, the calculation result of the phosphoric acid content, etc. Using the setting data, the phosphoric acid release rate in the settling tank 4 is calculated by Equation 3 described later. Based on the calculation result, an organic material injection amount set value for the settling tank 4 is calculated and transmitted to the organic material injection control means 13. The organic substance injection control means 13 controls the organic substance injector 12 according to the received organic substance injection amount setting value to adjust the amount of organic substance flowing into the settling tank 4.

  On the other hand, the phosphoric acid release rate calculating means 11 uses the data such as the excess sludge concentration and the phosphoric acid content measured by the excess sludge concentration meter 2 and the initial setting data such as the precipitation tank volume and the calculation coefficient. The amount of phosphoric acid contained in the supernatant liquid separated in 4 is calculated and transmitted to the calcium injection control means 14.

  The calcium injection control means 14 calculates the calcium injection amount from the received phosphoric acid amount and the inflow flow rate of the supernatant liquid flowing into the crystallization tank 5 measured by the flow meter 9, and the calculation result is calculated as the calcium injection machine 10. Send to. The calcium injector 10 injects the set calcium injection amount into the crystallization tank 5 by controlling the valve opening degree of the injection valve and the like.

  FIG. 2 is a block diagram of the phosphoric acid release rate calculating means 11 of this embodiment. As shown in FIG. 2, the phosphoric acid release rate calculating means 11 is mainly composed of a CPU 111, an input / output unit 100, and a memory 112.

  The memory 112 stores a program group such as a residence time calculation 114, a target phosphoric acid release rate calculation 115, an organic substance amount calculation 116 necessary for phosphoric acid release, a phosphoric acid release amount calculation 118, and a database 113. .

  The input / output unit 100 is a communication interface, and via a network 120, a terminal 119, a phosphoric acid content calculation unit 200, a surplus sludge concentration meter 2, a surplus sludge flow meter 20, an organic substance injection control unit 13, a calcium injection control unit 14 Connected. Data is transmitted / received to / from each other via the input / output unit 100 and the data in the database 113 is updated.

  The CPU 111 executes the program group stored in the memory 112 at regular intervals or occurrence of an event, and the phosphoric acid content data calculated by the phosphoric acid content calculating means 200 and the excess sludge measured by the excess sludge concentration meter 2. Concentration data, surplus sludge flow rate data measured by the surplus sludge flow meter 20 and the like are input, and the amount of organic matter injected and the amount of phosphoric acid released in the settling tank 4 are calculated. It transmits to the control means 14.

  FIG. 3 is a flowchart showing a calculation flow of the phosphoric acid release rate calculation means 11. The CPU 111 of the phosphoric acid release rate calculating means 11 executes the program in the memory 112 in the following steps, for example.

  In step S1, the measured values, the apparatus structure such as the sedimentation tank volume and the crystallization tank volume, and the constants of the arithmetic expression are read out from the database 113. In step S2, the time for which the excess sludge that has flowed into the settling tank 4 stays is calculated by, for example, Equation 1, using the program for the stay time calculation 114.

Here, T is the residence time (h), F is the excess sludge flow rate (m ³ / h), and C is the sedimentation tank volume (m ³ ).

  In step S3, the target value of the release rate required to release the phosphoric acid stored in the excess sludge is calculated by the program of the target phosphate release rate calculation 115, for example, using Equation 2. SS (Susupended Solid) is the amount of suspended solids in water and represents the amount of excess sludge.

Here, V1 is the target phosphoric acid release rate (gP / m ³ / h), R is the phosphoric acid content (gP / gSS), X is the excess sludge concentration (gSS / m ³ ), and T is the residence time ( h).

  In step S4, the target phosphoric acid release rate obtained in Equation 2 is substituted by using the phosphoric acid release rate equation (3), for example, according to the program of the organic substance amount calculation 116 necessary for phosphoric acid release, and phosphoric acid is obtained. The organic substance concentration A required for release is calculated. COD (Chemical Oxygen Demand) is a chemical oxygen demand and represents the amount of organic matter.

Where V is the phosphate release rate (gP / m ³ / h), q is the maximum specific phosphorus release rate (gP / gSS / h), A is the organic substance concentration (gCOD / m ³ ), and R is the phosphate content. (GP / gSS), X is the excess sludge concentration (microorganism concentration) (gSS / m ³ ), Ks is the organic matter saturation constant (gCOD / m ³ ), and Kpp is the polyphosphoric acid content saturation constant (gP / gSS). The constant Ks and the constant Kpp can be obtained experimentally.

  The relationship between the organic substance concentration A and the phosphoric acid release rate V is indicated by a curve in which the phosphoric acid release rate V increases as the organic substance concentration A increases and eventually becomes saturated. For this reason, when the target phosphoric acid release rate is calculated by Equation 2, the organic substance concentration A corresponding to this can be determined, and the organic substance injector 12 is controlled so as to obtain the obtained organic substance concentration. Here, in many cases, the surplus sludge that flows in contains almost no organic matter, and therefore, the concentration is controlled so as to obtain the required organic matter concentration.

  In step S5, the concentration of phosphoric acid flowing out from the sedimentation tank 4 is calculated by the program of the phosphoric acid release amount calculation 118, for example, using Equation 4.

Here, Pi is the phosphoric acid concentration (gP / m ³ ), R is the phosphoric acid content (gP / gSS), and X is the excess sludge concentration (microorganism concentration) (gSS / m ³ ).

  In step S6, the calculation result is stored in the database 113.

  The amount of organic matter calculated in Equation 3 is sent to the organic matter injection control means 13. The organic substance injection control means 13 controls the organic substance injector 12 to control the amount of organic substance flowing into the settling tank 4.

  Further, the phosphoric acid concentration calculated by the equation 4 is sent to the calcium injection control means 14. The calcium injection control means 14 calculates a calcium injection rate by, for example, Equation 5, and controls the calcium injector 10 to control the calcium injection amount into the crystallization tank 5.

Here, W is calcium infusion rate (gCa / m ^3), Pi is phosphoric acid concentration ^{(gP / m 3), K1} , K2 are coefficients. As the coefficients K1 and K2, a coefficient set from the molar ratio of calcium and phosphorus or a coefficient confirmed by experiments is used.

  FIG. 4 is a block diagram of the phosphoric acid content calculating means 200. FIG. 4 shows an embodiment applied to the anaerobic aerobic method which is one of the activated sludge processes.

  As shown in FIG. 4, the activated sludge process of the present embodiment is a biological reaction tank composed of an anaerobic tank 203 connected to a flow path 210 through which inflow sewage flows, and an aerobic tank 204 adjacent to the anaerobic tank 203, The final sedimentation basin 205 connected to the biological reaction tank, the flow path 206 connected to the final sedimentation basin 205 for flowing effluent water, the flow path 207 for flowing back sludge from the final sedimentation basin 205 to the anaerobic tank 203, and excess sludge are extracted. A water quality meter 201 installed at the outlet of the anaerobic tank 203, a water quality meter 202 installed at the outlet of the aerobic tank 204, and a phosphoric acid content calculating means 200 connected to the water quality meters 201, 202. Composed.

  The anaerobic aerobic method includes an anaerobic tank 203, a biological reaction tank having an aerobic tank 204, and a final sedimentation tank 205. Inflow sewage including municipal sewage, industrial wastewater, and rainwater is first settled and removed in a sedimentation basin (not shown), and a supernatant liquid containing organic matter, phosphorus, ammonia nitrogen, etc. flows to the anaerobic tank 203. It is sent as inflow sewage by the channel 210.

  The anaerobic tank 203 is maintained in an anaerobic state where no dissolved oxygen is present, and the phosphoric acid stored in the cells from the activated sludge is released into the liquid. During the release of phosphoric acid, activated sludge adsorbs organic matter and accumulates in the cells. For this reason, in the anaerobic tank 203, phosphorus increases and organic matter decreases.

  The liquid mixture in the anaerobic tank 203 is guided to the aerobic tank 204. The aerobic tank 204 is sprayed with air supplied from a blower to stir the mixed solution and supply oxygen into the activated sludge. In an aerobic state, the activated sludge oxidizes and decomposes the adsorbed organic matter and the organic matter in the mixed solution into water and carbon dioxide. In addition, the phosphate in the mixed solution is taken into the cells. The amount of phosphoric acid intake is usually excessive in excess of that released in the anaerobic tank 203, so that the phosphoric acid in the liquid decreases and the phosphoric acid in the activated sludge increases throughout the anaerobic aerobic process. The mixed solution flows out from the aerobic tank 204 and is guided to the final sedimentation basin 205, and the activated sludge in the mixed solution is gravity settled. The supernatant liquid is discharged into rivers and oceans after being disinfected and sterilized as treated water.

  The precipitated activated sludge has a high concentration, and most of the activated sludge is returned to the anaerobic tank 203 through the flow path 207 as return sludge. In the anaerobic tank 203 and the aerobic tank 204, microorganisms in the activated sludge proliferate in response to the reaction and increase the activated sludge concentration. To discharge. The phosphoric acid retained in the excess sludge corresponds to the amount of phosphorus removed in the entire process.

  The intake and release of phosphoric acid in activated sludge varies depending on the quality and flow rate of influent sewage, plant operating conditions, or activated sludge management conditions, and fluctuates gradually or suddenly.

  A water quality meter 201 is arranged at the outlet of the anaerobic tank 203 and a water quality meter 202 is arranged at the outlet of the aerobic tank 204, and the phosphoric acid concentration and the activated sludge concentration are measured. The phosphoric acid content calculating means 200 calculates the phosphoric acid content stored in the activated sludge based on the data measured by the water quality meters 201 and 202 using, for example, Equation 6.

Here, R is phosphoric acid content (gP / gSS), P1 is anaerobic tank outflow (terminal) phosphorus concentration (gP / m ³ ), S1 is an anaerobic tank outflow (terminal) sludge concentration (gSS / m ³ ), P2 Is the aerobic tank outflow (terminal) phosphorus concentration (gP / m ³ ), S2 is the aerobic tank outflow (terminal) sludge concentration (gSS / m ³ ), and δ is the microbial cell phosphorus content (gP / gSS).

  The phosphoric acid content R stored in the activated sludge is used as the phosphoric acid content contained in the surplus sludge from the change in the phosphorus concentration at the outlet of the anaerobic tank 203 to the outlet of the aerobic tank 204 in the activated sludge process. In the present embodiment, the reaction in the final sedimentation basin 205 is not included, but the activated sludge staying in the final sedimentation basin 205 can be obtained by disposing the water quality meter on the amount of water discharged from the flow path 206 and surplus sludge from the flow path 208. The phosphoric acid content of may be calculated.

  As another example of the calculation by the phosphoric acid content calculating means 200, the phosphoric acid content may be calculated using a program that models the entire activated sludge process. For example, by applying a model such as “activated sludge model” published by the International Water Environment Association (IWA), inflow conditions (water volume, organic matter, phosphorus, nitrogen, water temperature, alkalinity, sludge volume, etc.), facility specifications (Civil engineering dimensions, tank division, piping (circulation, inflow step, etc.)), operation amount (return amount, surplus amount, circulation amount, air flow rate), sludge conditions (sludge concentration, sludge settling rate), chemical addition amount, etc. As a condition, the phosphoric acid content of excess sludge may be calculated.

  In this example, an application example using surplus sludge from the activated sludge process of a sewage treatment plant as a raw material has been explained, but even when applied to an activated sludge process in general office wastewater treatment, individual information content and items are Although different, the basic scheme can be applied in exactly the same way.

  According to this embodiment, even if fluctuations in phosphoric acid stored in excess sludge or fluctuations in phosphoric acid flowing into the crystallization tank occur, phosphorus can be recovered stably and with high efficiency.

  In addition, since excessive calcium injection can be prevented, residual calcium in the wastewater can be reduced, which can greatly contribute to water environment conservation as well as the calcium injection cost control. By reducing the precipitation of residual calcium, the life of the phosphorus recovery device can be extended and the life cycle cost can be reduced.

  In addition, since calcium phosphate can be stably produced, it is possible to establish a system that can be stably supplied to customers, and to build a useful and finite resource recycling network.

The block diagram of the control method of the phosphorus collection | recovery apparatus by crystallization by one Example of this invention. The block diagram of the phosphoric acid release rate calculating means of a present Example. The calculation flow figure of the phosphoric acid release rate calculating means of a present Example. The block diagram of the phosphoric acid content calculating means of a present Example.

Explanation of symbols

1, 6, 7, 8, 15, 16, 206, 207, 208, 210 Channel 2 Excess sludge concentration meter 4 Sedimentation tank 5 Crystallization tank 10 Calcium injector 11 Phosphoric acid release rate calculating means 12 Organic substance injector 13 Organic substance Injection control means 14 Calcium injection control means 100 Input / output unit 111 CPU
112 Memory 113 Database 114 Residence time calculation 115 Target phosphoric acid release rate calculation 116 Organic substance amount calculation necessary for phosphoric acid release 118 Phosphoric acid release amount calculation 119 Terminal 120 Network 200 Phosphoric acid content calculation means 201, 202 Water quality meter 203 Anaerobic tank 204 Aerobic tank 205 Final sedimentation basin

Claims (6)

In the control device of the phosphorus recovery device, the surplus sludge from the activated sludge process is settled and retained in a settling tank maintained in an oxygen-free anaerobic state , the supernatant liquid is guided to the crystallization tank, and calcium is added and recovered as calcium phosphate. A phosphoric acid content calculating means for calculating a phosphoric acid content in surplus sludge from data measured by a water quality measuring instrument installed in the activated sludge process, and a phosphoric acid content calculated by the phosphoric acid content calculating means. The phosphoric acid release rate in the settling tank is calculated from the measurement data including the acid content and the excess sludge concentration measured by the excess sludge concentration meter, and the organic substance concentration necessary for the phosphoric acid release is calculated from the calculated phosphate release rate. And controlling the injection amount of the organic substance injection device for injecting the organic substance into the precipitation tank so that the organic substance concentration calculated by the phosphoric acid release speed calculation means is obtained. Controller phosphorus recovery device according to crystallization with an organic substance injection control means.   A calcium injection control means for controlling the calcium injection amount of a calcium injection machine for injecting calcium into the crystallization tank is provided, and the phosphoric acid content calculated by the phosphoric acid content calculation means is measured by a surplus sludge concentration meter. Calculate the phosphoric acid concentration of the supernatant liquid flowing out from the settling tank from the excess sludge concentration, the calcium injection control means calculates the calcium injection amount based on the calculated phosphoric acid concentration, and calculates the calcium of the calcium injector The control device for the phosphorus recovery device by crystallization according to claim 1, which controls the injection amount.   The phosphoric acid content calculating means calculates the phosphoric acid content accumulated in the excess sludge from the phosphoric acid concentration measured in the anaerobic tank of the activated sludge process and the activated sludge concentration measured in the aerobic tank. The control apparatus of the phosphorus collection | recovery apparatus by the crystallization of Claim 1 or 2. The phosphoric acid content calculation means calculates the phosphoric acid content in the surplus sludge that settles and stays in the settling tank maintained in an anaerobic state without oxygen from the data measured by the water quality meter installed in the activated sludge process. The acid release rate calculation means calculates the phosphate release rate in the settling tank from the measurement data including the phosphoric acid content calculated by the phosphoric acid content calculation means and the excess sludge concentration measured by the excess sludge concentration meter. Then, the organic substance concentration required for the phosphoric acid release is calculated from the calculated phosphoric acid release rate, and the organic substance injection control means puts the organic substance concentration in the precipitation tank so as to be the organic substance concentration calculated by the phosphoric acid release speed calculation means. A method for controlling a phosphorus recovery apparatus by crystallization, in which the injection amount of an organic substance injection machine for injecting organic substances is controlled, the supernatant liquid is guided to a crystallization tank, and calcium is added and recovered as calcium phosphate.   The phosphoric acid release rate calculating means calculates the phosphoric acid concentration of the supernatant based on the phosphoric acid content calculated by the phosphoric acid content calculating means, and the calcium injection control means calculates the calculated phosphoric acid. The method for controlling a phosphorus recovery apparatus by crystallization according to claim 4, wherein the calcium injection amount of the calcium injector is controlled by the concentration.   The phosphoric acid content calculating means calculates the phosphoric acid content accumulated in the excess sludge from the phosphoric acid concentration measured in the anaerobic tank of the activated sludge process and the activated sludge concentration measured in the aerobic tank. The control method of the phosphorus collection | recovery apparatus by the crystallization of Claim 4 or 5.

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