JP2017113677A - Wastewater treatment system, air supply amount control device and air supply amount control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress energy consumption required for blowing.SOLUTION: A wastewater treatment system 1 comprises: plural reaction tanks 10; blowing ducts 30; blowing units 20; and an air supply amount control part 40 for controlling an air supply amount to the reaction tanks 10. The air supply amount control part 40 comprises: a water quality measurement part for measuring a state of wastewater in the reaction tanks 10; a required air amount acquisition part for acquiring a total required air amount which is a total amount of a required air amount on the all reaction tanks 10 for making quality of the wastewater in the respective reaction tanks 10 a prescribed target water quality based on the measurement result of the water quality measurement part; a target inside-of-duct pressure calculation part for calculating target inside-of-duct pressure on the blowing ducts 30 required for supplying the total required air amount; and a blowing control part for controlling air supply from the blowing units 20 so that pressure in the respective blowing ducts 30 becomes the target inside-of-duct pressure. The target inside-of-duct pressure is changed according to the state of the wastewater in the reaction tanks 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wastewater treatment system, an air supply amount control device for a wastewater treatment device, and an air supply amount control method for a wastewater treatment device.

  As a wastewater treatment system for treating wastewater such as domestic wastewater or factory wastewater, various treatment methods including a standard activated sludge method have been put into practical use. In the wastewater treatment system, an aeration process is performed in which air is supplied to aerobic microorganisms existing in the reaction tank while the wastewater to be treated flows into the reaction tank. As a result, the organic matter contained in the waste water in the reaction tank is decomposed by the biological treatment of the aerobic microorganism, and a stable treated water quality is obtained.

  Air for aeration treatment in the reaction tank is supplied from a blower through a blower pipe. For example, as shown in Patent Document 1, the blower controls the amount of air to be supplied so that the amount of air necessary for biological treatment in the reaction tank is obtained. The blower may supply air so that the pressure in the blower pipe is constant. When the pressure in the blow pipe is made constant, the pressure in the blow pipe is set to such a value that a necessary amount of air can be supplied in order to reliably perform biological treatment in the reaction tank. Therefore, the pressure in the blast pipe is assumed to have the largest load of wastewater that has flowed into the reaction tank (for example, the concentration of ammoniacal nitrogen and BOD that are biological treatment targets), and biological treatment is possible even at the assumed maximum load. It is set to a value that is sufficient.

Japanese Patent Laid-Open No. 9-47780

  However, when the pressure in the blast pipe is set assuming the maximum load, if the load in the reaction tank is lower than the maximum load, more air than necessary is supplied. In this case, although the amount of air into the reaction vessel is limited by a valve provided in the blower pipe, the blower itself supplies air so as to have a pressure assuming a maximum load. It becomes useless. That is, when the pressure in the blower pipe is controlled to be constant, the energy consumption required for blowing air is higher than the energy required for actually blowing.

  This invention is made | formed in view of the above, Comprising: It aims at providing the wastewater treatment system, the air supply amount control apparatus, and the air supply amount control method which suppress the energy consumption required for ventilation.

  In order to solve the above-described problems and achieve the object, a wastewater treatment system of the present disclosure includes a plurality of reaction tanks that perform biological treatment on wastewater, and a blower pipe that is a pipe connected to the plurality of reaction tanks, A blower unit that supplies air for performing the biological treatment to a plurality of the reaction tanks via the blower pipe, and an air supply amount control unit that controls an air supply amount to the reaction tanks, The air supply amount control unit is provided in the reaction tank, measures a state of waste water in the reaction tank, and determines the waste water in the reaction tank based on a measurement result of the water quality measurement unit. Required air quantity acquisition unit for acquiring the total required air quantity that is the total quantity in all the reaction tanks, and the air in the blast pipe required to supply the total required air quantity Target pipe that calculates the target pipe internal pressure A pressure calculating unit, and a ventilation control unit that controls air supply from the blowing unit so that the pressure in the blowing pipe becomes the target pipe internal pressure, and the target pipe internal pressure is within the reaction tank. It changes according to the state of waste water.

  In the wastewater treatment system, the target pipe internal pressure calculation unit increases the target pipe internal pressure when the total required air amount increases, and decreases the target pipe internal pressure when the total required air amount decreases. Is preferred.

  In the wastewater treatment system, the blower pipe is provided in the branch pipe, a mother pipe connected to the blower unit, a plurality of branch pipes branched from the mother pipe and connected to the plurality of reaction vessels, respectively. An air supply amount control unit, based on the required air amount and the air supply amount to the branch pipe, so that the air supply amount to the reaction tank becomes the required air amount, It is preferable to have an introduction air control unit that adjusts the opening degree of the introduction valve.

  In the wastewater treatment system, the blower unit includes a plurality of blowers that sucks air through an inlet vane and exhausts by rotation of blades, and the blower control unit includes the number of operating blowers and the inlet vanes. It is preferable to control at least one of the opening degree and the rotational speed of the blade portion.

  In the wastewater treatment system, the water quality measurement unit, as the state of the wastewater in the reaction tank, nitrate nitrogen concentration, ammonia nitrogen concentration, dissolved oxygen amount, and the amount of dissolved oxygen in the reaction tank It is preferable to measure at least one of the inflows of wastewater.

  In the wastewater treatment system, the water quality measurement unit measures at least one of nitrate nitrogen concentration, ammoniacal nitrogen concentration, and dissolved oxygen content of the wastewater as the quality of wastewater in the reaction tank, It is preferable that the air amount acquisition unit calculates the required air amount so that the quality of the wastewater becomes the target water quality.

  In the wastewater treatment system, the required air amount acquisition unit is a water quality air amount relationship that is a relationship between the amount of air supplied to the reaction tank and the amount of change in the quality of the wastewater when that amount of air is supplied. Based on the relationship storage unit, the water quality air quantity relationship, the water quality measurement result by the water quality measurement unit and the target water quality, the amount of air necessary to change the waste water quality to the target water quality, It is preferable to have a required air amount calculation unit that calculates the required air amount.

  In the wastewater treatment system, the relationship storage unit stores the water quality air amount relationship as a first-order lag system in which a change in the quality of the wastewater is delayed with respect to a change in the amount of air supplied to the reaction tank, It is preferable that the required air amount calculation unit updates the required air amount based on the water quality measurement result at every elapse of a predetermined time by the water quality measurement unit.

  In order to solve the above-described problems and achieve the object, an air supply amount control device of the present disclosure includes a plurality of reaction vessels that perform biological treatment on wastewater, and a blower tube that is a tube connected to the plurality of reaction vessels. And an air supply amount control device that controls an air supply amount of a wastewater treatment device having a blower unit that supplies air for performing the biological treatment to a plurality of the reaction tanks via the blower pipe. The air supply amount control device is provided in the reaction tank and measures the state of waste water in the reaction tank, and based on the measurement result of the water quality measurement part, the waste water in the reaction tank has a predetermined target. The required air amount acquisition unit for acquiring the total required air amount, which is the total amount of the required air amount for achieving water quality, in the entire reaction tank, and the pressure of the air in the blower pipe required for supplying the total required air amount A target pipe internal pressure calculation unit that calculates a target pipe internal pressure, and a blow control unit that controls air supply from the blow unit so that the pressure in the blow pipe becomes the target pipe internal pressure. The target pipe internal pressure changes according to the state of the waste water in the reaction tank.

  In order to solve the above-described problems and achieve the object, an air supply amount control method of the present disclosure includes a plurality of reaction tanks that perform biological treatment on wastewater, and a blower pipe that is a pipe connected to the plurality of reaction tanks. And an air supply amount control method for controlling an air supply amount of a wastewater treatment apparatus having a blower unit that supplies air for performing the biological treatment to a plurality of the reaction tanks via the blower pipe. The air supply amount control method is a measurement step for measuring the state of waste water in the reaction tank, and the amount of air necessary for the waste water in the reaction tank to have a predetermined target water quality based on the measurement result of the state of the waste water. A required air amount acquiring step for acquiring a total required air amount that is a total amount in all reaction tanks, and a target for calculating a target pipe pressure that is a pressure of air in the blower pipe necessary for supplying the total required air amount A pipe internal pressure calculating step, and a ventilation control step for controlling the air supply from the blower unit so that the pressure in the blow pipe becomes the target pipe internal pressure, and the target pipe internal pressure is set in the reaction tank. It changes according to the state of wastewater.

  According to the present invention, energy consumption required for blowing can be suppressed.

FIG. 1 is a schematic diagram of a wastewater treatment system according to this embodiment. FIG. 2 is a block diagram illustrating a configuration of the control unit according to the present embodiment. FIG. 3 is a graph for explaining the water quality air quantity relationship. FIG. 4 is a graph showing an example of the relationship between the total required air amount and the target pipe pressure. FIG. 5 is a flowchart for explaining the control of the air supply amount to the reaction tank by the air supply amount control unit. FIG. 6 is a flowchart for explaining control of the blower by the blower control unit. FIG. 7 is a graph for explaining the control of the blower by the blower.

  Hereinafter, preferred embodiments of a wastewater treatment system according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Configuration of wastewater treatment system)
FIG. 1 is a schematic diagram of a wastewater treatment system according to this embodiment. As shown in FIG. 1, the wastewater treatment system 1 according to this embodiment includes reaction tanks 10A, 10B, and 10C, a blower unit 20, a blower pipe 30, and an air supply amount control unit 40. The wastewater treatment system 1 supplies the air from the blower unit 20 into the reaction tank 10 through the blower pipe 30 while controlling the amount of air supplied into the reaction tank 10 with the air supply amount control unit 40. The internal wastewater W is biologically treated with the activated sludge.

  Reaction tank 10A, 10B, 10C is a tank which has the aeration part 12 inside, and stores activated sludge. In the reaction tanks 10A, 10B, and 10C, waste water W flows from a sedimentation basin (not shown). The waste water W is water after a part of solid matter is separated from raw water by a sedimentation basin (not shown). Raw water here refers to waste water and sewage discharged from homes and factories. The air diffuser 12 aerates the stored activated sludge with the air supplied from the blower unit 20. The reaction tanks 10A, 10B, and 10C perform biological treatment on the waste water W using the aerated activated sludge, and discharge the treated water, which is the waste water W after the biological treatment, to a solid-liquid separation tank (not shown). In this solid-liquid separation tank (not shown), the treated water is further subjected to solid-liquid separation processing, and the water after the solid-liquid separation processing is discharged to the external environment, for example, after disinfection processing.

  The reaction vessels 10A, 10B, and 10C are provided in parallel. That is, the waste water W is supplied to the reaction tanks 10A, 10B, and 10C in parallel from the settling basin. However, the reaction vessels 10A, 10B, and 10C may be arranged in series with each other. That is, the reaction tank 10A may be connected to the reaction tank 10A, the waste water W after biological treatment in the reaction tank 10A may be introduced into the reaction tank 10B, and the biological treatment may be performed again in the reaction tank 10B. Moreover, although reaction tank 10A, 10B, 10C is a total of three aerobic tanks, the number is also arbitrary. Moreover, an anaerobic tank and an oxygen-free tank may be connected in series with the reaction tanks 10A, 10B, and 10C. Hereinafter, when the reaction vessels 10A, 10B, and 10C are not distinguished from each other, they are referred to as the reaction vessel 10.

  As shown in FIG. 1, the blower unit 20 has a plurality of blowers 22A, 22B, 22C, and 22D. The blowers 22A, 22B, 22C, and 22D are blowers having functions similar to each other. The blowers 22A, 22B, 22C, and 22D introduce air from the outside through the inlet vane, and exhaust the air introduced by the rotating blade portion. In the blowers 22A, 22B, 22C, and 22D, the opening degree of the inlet vane can be adjusted, and the rotation speed of the blade portion can also be adjusted. The blowers 22 </ b> A, 22 </ b> B, 22 </ b> C, and 22 </ b> D are connected to the blower pipe 30 in parallel with each other, and discharge air to the blower pipe 30. Hereinafter, the blowers 22 </ b> A, 22 </ b> B, 22 </ b> C, and 22 </ b> D are referred to as the blower 22 when not distinguished from each other. In addition, the number of the air blowers 22 which the air blow unit 20 has is arbitrary.

  The blower pipe 30 is a pipe that conducts air inside. The blower pipe 30 includes an introduction pipe 31, a mother pipe 32, branch pipes 34 </ b> A, 34 </ b> B, 34 </ b> C, and an introduction valve 36. One end of the introduction pipe 31 is branched and connected to the blower 22, and air is supplied from the blower 22. The other end of the introduction pipe 31 is connected to the mother pipe 32, and the air from each blower 22 is merged and the merged air A is conducted to the mother pipe 32. The mother pipe 32 is a single pipe. The branch pipes 34C, 34B, and 34A are connected in this order from the upstream side of the flow of the air A, that is, the blower 22 side.

  The branch pipe 34A is connected to the diffuser 12 of the reaction tank 10A on the side opposite to the connection part of the mother pipe 32, and supplies a part of the air A from the mother pipe 32 to the reaction tank 10A. The branch pipe 34B is connected to the diffuser 12 of the reaction tank 10B on the side opposite to the connection part of the mother pipe 32, and supplies a part of the air A from the mother pipe 32 to the reaction tank 10B. The branch pipe 34C is connected to the diffuser 12 of the reaction tank 10C on the side opposite to the connection part of the mother pipe 32, and supplies a part of the air A from the mother pipe 32 to the reaction tank 10C. The introduction valve 36 is attached to the branch pipes 34A, 34B, and 34C. The introduction valve 36 is a valve that is opened and closed by the air supply amount control unit 40, and adjusts the air supply amount to each reaction tank 10 by adjusting the opening thereof. Hereinafter, the branch pipes 34 </ b> A, 34 </ b> B, and 34 </ b> C will be referred to as branch pipes 34 when not distinguished from each other.

  The air supply amount control unit 40 as an air supply amount control device includes a control unit 42, a nitric acid meter 43 and an ammonia meter 44 as water quality measurement units, an intake air measurement unit 46, a mother pipe internal pressure measurement unit 47, and branch pipe air. A quantity measuring unit 48. The control unit 42 controls the amount of air supplied into each reaction tank 10 based on the measurement results of the nitric acid meter 43, the ammonia meter 44, the intake air measurement unit 46, the mother pipe internal pressure measurement unit 47, and the branch pipe air amount measurement unit 48. It is a control device. Details of the control unit 42 will be described later. Note that the air supply amount control unit 40 controls the air supply amount to the plurality of reaction tanks 10, but one air supply amount control unit 40 is provided for each reaction tank 10. The air supply amount may be controlled.

The nitric acid meter 43 is a sensor that is provided in each reaction tank 10 and measures the nitric acid concentration of the waste water W in the reaction tank 10. In this embodiment, the nitric acid of the waste water W is nitric acid (HNO ₃ ), nitrous acid (HNO ₂ ), nitrate nitrogen (NO ₃ —N), nitrite nitrogen (NO ₂ —N), nitrate nitrogen. This is a concept including NO _x that indicates both an assembly of nitrous acid and nitrite nitrogen, and nitric acid and nitrous acid. That is, the nitric acid concentration in the present embodiment is any one of nitric acid, nitrous acid, nitrate nitrogen, nitrite nitrogen, aggregation of nitrate nitrogen and nitrite nitrogen, and NO _x indicating both nitric acid and nitrite. May be the concentration.

The ammonia meter 44 is a sensor that is provided in each reaction tank 10 and measures the ammonia concentration of the waste water W in the reaction tank 10. The ammonia concentration of the waste water W is a concept including ammonia and ammoniacal nitrogen in the present embodiment. That is, the ammonia concentration in this embodiment may be any concentration of ammonia (NH ₃ ) and ammoniacal nitrogen (NH ₄ —N). That is, it can be said that the nitric acid meter 43 and the ammonia meter 44 measure the state of the waste water W in the reaction tank 10. In addition, although the water quality measurement part, ie, the nitric acid meter 43 and the ammonia meter 44, are provided for each reaction tank 10, one water quality measurement part is provided in the plurality of reaction tanks 10. Also good.

  The intake air measurement unit 46 is provided on the intake side of each blower 22 and measures the amount of air taken in by the blower 22. The mother pipe internal pressure measurement unit 47 is attached to the mother pipe 32 and measures the pressure in the mother pipe 32, that is, the pressure of the air supplied by each blower 22. More specifically, the mother pipe internal pressure measurement unit 47 is provided on the upstream side of the air A flow with respect to the branch pipe 34C, that is, on the upstream side of the air A flow with respect to the connection parts with all the branch pipes 34. The branch air amount measuring unit 48 is provided in each branch pipe 34 and measures the amount of air supplied to each branch pipe 34. More specifically, the branch pipe air amount measurement unit 48 is provided on the upstream side of the air flow from the introduction valve 36 and measures the amount of air supplied toward the introduction valve 36.

(Water treatment in reaction tank)
Next, biological treatment of the waste water W in the reaction tank 10 will be described. In the reaction tank 10, nitrification reaction, that is, ammonia nitrogen (NH ₄ -N) in the water to be treated is expressed by the following reaction formula (1) by nitrifying bacteria that are aerobic microorganisms in activated sludge under aerobic conditions. As in (3) to (3), it is nitrified to nitrite nitrogen (NO ₂ —N) or nitrate nitrogen (NO ₃ —N).

NH ₃ + O ₂ + 2e ⁻ + 2H ⁺ → NH ₂ OH + H ₂ O (1)
NH ₂ OH + H ₂ O → NO ₂ ⁻ + 5H ⁺ + 4e ⁻ (2)
NO ₂ ⁻ + 0.5O ₂ → NO ₃ ⁻ (3)

On the other hand, in a region where the amount of oxygen in the water to be treated in the reaction tank 10 is small, a denitrification reaction (anaerobic reaction) due to denitrifying bacteria occurs because the amount of oxygen is small. If a sufficient carbon source is supplied to a region where the denitrification reaction occurs (denitrification reaction region), the denitrification reaction can sufficiently proceed. As a result, a region where the denitrification reaction is performed partially occurs in the reaction tank 10. As a result, as shown in the following reaction formulas (4) to (10), nitrous oxide (N ₂ O) gas generated due to insufficient nitrification is not decomposed or nitrous oxide is not generated. Nitrous acid can be reduced or decomposed into nitrogen and carbon dioxide to remove nitrogen.

NO ₂ ⁻ + 3H ⁺ + 2e ⁻ → 0.5N ₂ O + 1.5H ₂ O (4)
NO ₂ ⁻ + H ⁺ +2 (H) → 0.5N ₂ O + 1.5H ₂ O (5)
NO ₃ ⁻ + H ⁺ +5 (H) → 0.5N ₂ + 3H ₂ O (6)
NO ₃ ⁻ + 2H → NO ₂ ⁻ + H ₂ O (7)
NO ₂ ⁻ + H ⁺ + (H) → NO + H ₂ O (8)
NO + (H) → 0.5N ₂ O + 0.5H ₂ O (9)
N ₂ O + 2 (H) → N ₂ + H ₂ O (10)

  The nitric acid meter 43 detects the degree of progress of the denitrification reaction, that is, the degree of decomposition of nitric acid, by measuring the nitric acid concentration of the wastewater W in the reaction tank 10. The ammonia meter 44 detects the degree of progress of the nitrification reaction, that is, the degree of decomposition of ammonia, by measuring the ammonia concentration of the waste water W in the reaction tank 10. The air supply amount control unit 40 controls the amount of air supplied to the reaction tank 10 based on the measurement results of the nitric acid meter 43 and the ammonia meter 44. For example, when the nitric acid concentration is higher than a predetermined numerical range, the air supply amount control unit 40 determines that the denitrification reaction is insufficient and reduces the amount of air supplied to the reaction tank 10 so that the nitric acid concentration is a predetermined numerical value. When the temperature is lower than the range, the amount of air supplied to the reaction tank 10 is increased on the assumption that the denitrification reaction proceeds so much that the nitrification reaction is insufficient. Similarly, when the ammonia concentration is higher than the predetermined numerical range, the air supply amount control unit 40 determines that the nitrification reaction is insufficient and increases the amount of air supplied to the reaction tank 10 so that the ammonia concentration is a predetermined numerical value. When the temperature is lower than the range, the amount of air supplied to the reaction tank 10 is decreased because the nitrification reaction proceeds too much and the denitrification reaction is insufficient.

  The nitric acid meter 43 is arranged on the upstream side of the waste water W in the reaction tank 10, that is, on the side where the waste water is supplied (the sedimentation basin side not shown) than the ammonia meter 44. The inside of the reaction tank 10 is from the upstream side to the downstream side of the waste water W, that is, the side from which the treated water is discharged from the side where the waste water W is supplied (the sedimentation pond side not shown) (the solid separation not shown). The tank is divided into an upstream processing area and a downstream processing area. The upstream region and the downstream region are regions in which progress degrees of the nitrification treatment and the denitrification treatment are different from each other. The upstream region is a region on the upstream side of the waste water W, and is a region where the nitrification process and the denitrification process proceed at substantially the same predetermined ratio, for example. The downstream region is a region on the downstream side of the waste water W from the upstream region, and nitrification treatment and denitrification treatment are performed as in the upstream region. However, the progress speed of the nitrification process in the downstream area is higher than the progress speed of the nitrification process in the upstream area and the progress speed of the denitrification process in the downstream area. The nitric acid meter 43 is provided between the upstream region and the downstream region (for example, the central position when the waste water W extends from the upstream side to the downstream side), and the ammonia meter 44 is located downstream of the nitric acid meter 43. Arranged in the downstream region.

  As described above, the air supply amount control unit 40 controls the amount of air in the reaction tank 10 based on the detection results of the nitric acid meter 43 and the ammonia meter 44, and performs nitrification treatment and denitrification in the reaction tank 10. Perform simultaneous nitrification and denitrification control including both biological treatment and treatment. However, the air supply amount control unit 40 may not perform the simultaneous nitrification denitrification process in the reaction tank 10. For example, the air supply amount control unit 40 may have one of the nitric acid meter 43 and the ammonia meter 44, and may control the air amount in the reaction tank 10 based on the measurement result. In addition, for example, the air supply amount control unit 40 has a dissolved oxygen concentration meter that measures the amount of dissolved oxygen in the waste water W in the reaction tank 10 as a water quality measurement unit instead of the nitric acid meter 43 and the ammonia meter 44. May be. In this case, the air supply amount control unit 40 controls the amount of air supplied to the reaction tank 10 based on the amount of dissolved oxygen in the waste water W measured by the dissolved oxygen meter so that the amount of dissolved oxygen becomes a constant value ( Control of dissolved oxygen amount). In the case of this dissolved oxygen amount control, an anaerobic tank or an oxygen-free tank may be connected in series with the reaction tank 10, and the waste water W after nitrification in the reaction tank 10 may be denitrified.

  The air supply amount control unit 40 may have a flow meter that measures the inflow amount of the waste water W in the reaction tank 10 as a water quality measurement unit instead of the nitric acid meter 43 and the ammonia meter 44. In this case, the air supply amount control unit 40 is based on the inflow amount of the waste water W into the reaction tank 10 measured by the flow meter, and supplies air to the reaction tank 10 to set the amount of waste water W to the target concentration. The amount is controlled (inflow water amount control). In the case of this inflow control, an anaerobic tank or an oxygen-free tank may be connected in series to the reaction tank 10, and the waste water W after nitrification in the reaction tank 10 may be denitrified. Thus, if the wastewater treatment system 1 controls the amount of air supplied to the reaction tank 10 based on the measurement result of the water quality measurement unit, the simultaneous nitrification denitrification control, dissolved oxygen amount control, inflow water amount described above Arbitrary air amount control other than control may be performed. In addition, the wastewater treatment system 1 divides a series for performing different treatments (for example, a series for performing simultaneous nitrification denitrification control and a series for performing dissolved oxygen amount control), and performs any one of the respective treatments (for example, Any one of the simultaneous nitrification denitrification control and the dissolved oxygen amount control system) may be performed.

(Configuration of control unit)
Next, the control unit 42 included in the air supply amount control unit 40 will be described. FIG. 2 is a block diagram illustrating a configuration of the control unit according to the present embodiment. The control unit 42 is an arithmetic device such as a computer. As shown in FIG. 2, the control unit 42 includes a water quality measurement result acquisition unit 70, a necessary air amount acquisition unit 72, a target pipe pressure calculation unit 74, a ventilation control unit 76, and an introduction air control unit 78. .

  The water quality measurement result acquisition unit 70 acquires the state of the waste water W in the reaction tank 10 from the nitric acid meter 43 and the ammonia meter 44, that is, the measurement results of the nitric acid concentration and ammonia concentration of the waste water W. When the water quality measurement unit is a dissolved oxygen meter, the water quality measurement result acquisition unit 70 acquires the amount of dissolved oxygen in the reaction tank 10 as the state of the waste water W. When the water quality measurement unit is a flow meter, the water quality measurement result acquisition unit 70 acquires the amount of waste water W that has flowed into the reaction tank 10 as the state of the waste water W. That is, the state of the waste water W in the reaction tank 10 is a measurement target measured by the water quality measurement unit. In other words, the water quality measurement unit can measure at least one of the nitric acid concentration, the ammonia concentration, the dissolved oxygen amount, and the inflow amount of the waste water W in the reaction tank 10 as the state of the waste water W.

  Based on the measurement result of the state of the waste water W acquired by the water quality measurement result acquisition unit 70, the necessary air amount acquisition unit 72 is configured to have a required air amount for making the water quality of the waste water W in the reaction tank 10 a predetermined target water quality. The total required air amount that is the total amount in all the reaction vessels 10 is acquired. Specifically, the required air amount acquisition unit 72 includes a relationship storage unit 82 and a required air amount calculation unit 84. In addition, the water quality here means the concentration or amount of a predetermined component contained in the wastewater W, and in the example of this embodiment, the concentration of nitric acid and the ammonia concentration of the wastewater W. Further, the water quality may be, for example, the amount of dissolved oxygen in the wastewater W.

  The relationship storage unit 82 stores the water quality air amount relationship. The water quality air amount relationship is a relationship between the amount of air supplied to the reaction vessel 10 and the amount of change in water quality in the reaction vessel 10 when that amount of air is supplied. The relationship storage unit 82 stores the water / air relationship as a primary delay system in which a change in the water quality in the reaction tank 10 is delayed with respect to a change in the amount of air supplied to the reaction tank 10. This will be specifically described below.

  FIG. 3 is a graph for explaining the water quality air quantity relationship. FIG. 3 is a graph showing an example of the amount of change in the ammonia concentration when air is supplied to the reaction vessel 10. The horizontal axis of FIG. 3 indicates time, the left side of the vertical axis indicates the amount of supply air supplied to the reaction tank 10, and the right side of the vertical axis indicates the ammonia concentration of the waste water W in the reaction tank 10. A line segment L1 in FIG. 3 indicates the amount of supplied air for each hour. A line segment L2 indicates the ammonia concentration for each time when the ammonia concentration changes according to the water quality air amount relationship when the supply air amount changes as in the line segment L1.

As shown in the line segment L1, in the example of FIG. 3, the supply air amount is increased from M ₁ to M ₂ at time t ₁ . As shown in line L2, when in accordance with the water quality air volume relationship, ammonia concentration is from time t ₁ to time t ₂ delayed remain concentration P _1, it starts to decrease the ammonia concentration from time t ₂ , the ammonia concentration lowered at a constant speed until time t _3, the rate of decrease in ammonia concentration decreases from time t _3, reaches the concentration P ₂ at time t _4, converges remain concentration P _2. Here, the change value of the supply air amount when the supply air amount is changed from M ₁ to M ₂ is defined as the change amount of the supply air per unit (for example, the change amount of air is 1 m ³ ). Then, the variation in the concentration of the ammonia concentration P ₁ in this case to P _2, ie the variation in water quality after the convergence in the case of varying only the unit amount supplied air quantity, and K. The time between the time _{t 1} to _{t 2,} i.e. the dead time and Ls. The time from time t ₂ to t _3, i.e. the first-order lag time is Ts. When the transfer function of the ammonia concentration related to the supply air amount and time is y, the water quality air amount relationship is as shown in the following equation (11).

y = (K · e ^−Ls ) / (1 + Ts) (11)

The relationship storage unit 82 stores a water quality air amount relationship in which the values of K, Ls, and Ts measured in advance are applied to the above equation (11). For example, based on the detection result of the time from time t ₂ to t ₄ , the relationship storage unit 82 calculates a predetermined ratio (here 63%) of the detected time from time t ₂ to t _3. Is stored as Ts which is the time of. In this example, the relationship between the ammonia concentration and the supply air amount has been described. However, if the values of K, Ls, and Ts are measured in advance, the water quality air amount relationship is the relationship between the nitric acid concentration and the supply air amount. The present invention can also be applied to the relationship between each water quality and the supply air amount such as the relationship between the oxygen amount and the supply air amount. The relationship storage unit 82 in the present embodiment stores different water quality air amount relationships for the relationship between the ammonia concentration and the supply air amount and the relationship between the nitric acid concentration and the supply air amount.

  The required air amount calculation unit 84 illustrated in FIG. 2 reads the water quality air amount relationship from the relationship storage unit 82. The required air amount calculation unit 84 acquires a predetermined target water quality of the waste water W in the reaction tank 10, here a target concentration that is a value of the target ammonia concentration and the target nitric acid concentration. This target density is a predetermined numerical range set in advance. For example, the target concentration in the nitric acid concentration is a predetermined numerical range of 5.0 mg or less. For example, the target concentration in the ammonia concentration is 1.0 mg / L or more and 5.0 mg / L or less, and more preferably 1.0 mg / L or more and 2.0 mg / L or less. The required air amount calculation unit 84 calculates the required air amount of the reaction tank 10 based on the water quality air amount relationship, the target concentration, and the current nitric acid concentration and ammonia concentration of the waste water W acquired by the water quality measurement result acquisition unit 70. To do. The required air amount calculation unit 84 calculates the required air amount in the reaction tank 10 so that the nitric acid concentration of the waste water W becomes the target concentration and the ammonia concentration of the waste water W becomes the target concentration. The required amount of air is the amount of air necessary for setting the water quality of the reaction tank to a predetermined target water quality, that is, for setting both the ammonia concentration and the nitric acid concentration of the waste water W in the reaction tank to the target concentration. Are calculated as absolute values.

  Specifically, the required air amount calculation unit 84 calculates a difference concentration that is a difference between the target concentration and the concentration calculated by the water quality measurement result acquisition unit 70, and the ammonia concentration of the wastewater W is set to the difference concentration on the target concentration side. The required air amount is calculated so that the nitric acid concentration of the wastewater W changes by the difference concentration toward the target concentration side. Therefore, it can be said that the required air amount changes according to the value of the differential concentration. For example, when the ammonia concentration is taken into account, the required air amount calculation unit 84, when the calculated ammonia concentration is lower than the target concentration, the nitrification process proceeds too much as the differential concentration increases, that is, as the current ammonia concentration decreases. As a result, the required air amount is lowered. When the calculated ammonia concentration is higher than the target concentration, the required air amount calculation unit 84 increases the required air amount, assuming that the nitrification is not sufficient as the differential concentration increases, that is, the current ammonia concentration increases. Further, when considering the nitric acid concentration, the required air amount calculation unit 84 assumes that the nitrification treatment is not sufficient as the difference concentration increases, that is, the current nitric acid concentration decreases when the calculated nitric acid concentration is lower than the target concentration. Increase the required air volume. When the calculated concentration of nitric acid is higher than the target concentration, the required air amount calculation unit 84 decreases the required air amount because the denitrification process is not sufficient as the differential concentration increases, that is, the current nitric acid concentration increases.

  The required air amount calculation unit 84 calculates the required air amount for all the reaction tanks 10 and calculates the total value as the total required air amount. Since the required air amount changes based on the current state of the waste water W in the reaction tank 10, that is, the nitric acid concentration and the ammonia concentration, the total required air amount is similarly based on the current state of the waste water W in the reaction tank 10. Change.

  In addition, when performing the above-mentioned dissolved oxygen amount control, the required air amount calculation unit 84 reads the water quality air amount relationship indicating the relationship between the dissolved oxygen amount and the supply air amount, and the current quality acquired by the water quality measurement result acquisition unit 70 Based on the amount of dissolved oxygen in the wastewater W, the required amount of air in the reaction tank 10 is calculated so that the wastewater W has a predetermined target water quality (target dissolved oxygen amount). Moreover, when performing the above-mentioned inflow water amount control, the required air amount calculation part 84 calculates the required air amount for setting it as target water quality according to the inflow amount of the waste water W to the reaction tank 10. FIG. The required air amount calculation unit 84 stores the relationship, assuming that the required air amount for achieving the target water quality has a relationship according to the inflow amount of the waste water W into the reaction tank 10, and obtains a water quality measurement result acquisition unit. Based on the inflow amount of the wastewater W acquired by 70, the required air amount is calculated.

  The target pipe pressure calculation unit 74 shown in FIG. 2 calculates the target pipe pressure based on the value of the total required air amount. The target pipe internal pressure is the pressure of air in the blow pipe necessary for supplying the total necessary air amount. A relational expression such as the following expression (12) is established between the pressure P and the flow rate Q.

Q = C · A · (2 · P / ρ) ^0.5 (12)

  In Expression (12), C is a coefficient, A is a flow path area, and ρ is a fluid density.

  The target pipe pressure calculation unit 74 calculates the target pipe pressure (pressure P) when the flow rate Q is the total required air amount based on the equation (12).

  FIG. 4 is a graph showing an example of the relationship between the total required air amount and the target pipe pressure. The horizontal axis in FIG. 4 is the total required air amount, and the vertical axis is the target pipe pressure. As shown in FIG. 4, the target pipe pressure decreases as the total required air amount decreases, and increases as the total required air amount increases. Thus, the target pipe pressure changes in accordance with the change in the total required air amount, that is, the current state of the waste water W in the reaction tank 10. That is, the target pipe pressure becomes low when the total required air amount is small, for example, when the load is small or the nitrification process is too advanced. Furthermore, as shown in FIG. 4, the reduction rate of the target pipe pressure increases as the total required air amount increases.

  The air blow control unit 76 shown in FIG. 2 controls the air supply from the air blow unit 20 so that the pressure in the air blow pipe becomes the target pipe internal pressure. Specifically, the air blowing control unit 76 obtains the value of the air pressure in the mother pipe 32 measured by the mother pipe internal pressure measuring unit 47, and the air blowing unit so that the air pressure in the mother pipe 32 becomes the target pipe internal pressure. The air supply amount from 20 is controlled.

  The air blow control unit 76 adjusts the amount of air discharged from the air blower 22 by controlling the number of the air blowers 22 to be operated, the opening degree of the inlet vanes of the air blower 22, and the number of rotations of the blades, and the air pressure in the mother pipe 32. Is the target pipe pressure. When the target pipe internal pressure is higher than the current pipe internal pressure, the blower control unit 76 increases the opening degree of the inlet vane, increases the rotational speed of the blades, or increases the number of operating units to increase the discharge air amount. Increase. When the target pipe internal pressure is lower than the current pipe internal pressure, the air blow control unit 76 reduces the inlet vane opening, lowers the rotational speed of the blades, or reduces the number of operating units to reduce the discharge air amount. Decrease. The blower control unit 76 may control at least one of the number of the blower 22 that is operated, the opening degree of the inlet vane of the blower 22, and the rotational speed of the blade part.

  The introduction air control unit 78 acquires the value of the amount of air supplied to each branch pipe 34 measured by each branch pipe air amount measurement unit 48. The introduction air control unit 78 controls the opening degree of the introduction valve 36 based on the necessary air amount and the acquired air amount in the branch pipe 34 so that the air supply amount from the branch pipe 34 to the reaction tank 10 becomes the necessary air amount. adjust. When the amount of air in the branch pipe 34 is larger than the required amount of air, the introduction air control unit 78 reduces the opening of the introduction valve 36 (decreases the opening area), and the amount of air flowing into the reaction tank 10 becomes too large. Do not. The introduction air control unit 78 increases the opening degree of the introduction valve 36 (increases the opening area) when the necessary air amount fluctuates and increases, and when the necessary air amount decreases, the introduction air control unit 78 introduces the air. Reduce the valve opening. In the present embodiment, the air blowing control unit 76 changes the pipe internal pressure in the air blowing pipe 30 according to the required air amount, and supplies air so that the air amount follows the required air amount. Therefore, the amount of adjustment of the opening degree of the introduction valve 36 is lower in the introduction air control unit 78 than in the case where the target pipe pressure is kept constant. In other words, since the amount of air is always supplied to the blower pipe 30 as much as necessary, the introduction air control unit 78 introduces the air within a range in which the opening degree of the introduction valve 36 does not become too low. The opening degree of the valve 36 can be controlled.

(Control processing of air supply control unit)
Next, control processing of the air supply amount control unit 40 will be described using a flowchart. FIG. 5 is a flowchart for explaining the control of the air supply amount to the reaction tank by the air supply amount control unit. As shown in FIG. 5, the air supply amount control unit 40 first measures the nitric acid concentration and the ammonia concentration of the waste water W in each reaction tank 10 using the nitric acid meter 43 and the ammonia meter 44 (step S10).

  After measuring the nitric acid concentration and the ammonia concentration, the air supply amount control unit 40 uses the required air amount calculation unit 84 to calculate the required air amount of each reaction tank 10 based on the water quality air amount relationship and the measured concentration and target concentration. The total required air amount is calculated by calculating (step S12) and summing the required air amount of each reaction tank 10 (step S14). Specifically, the required air amount calculation unit 84 reads the water quality air amount relationship for each of the relationship between the ammonia concentration and the supply air amount and the relationship between the nitric acid concentration and the supply air amount from the relationship storage unit 82. The required air amount calculation unit 84 acquires a target concentration value for each of the ammonia concentration and the nitric acid concentration. The required amount of air in the reaction tank 10 is calculated so that the nitric acid concentration of the waste water W becomes the target concentration and the ammonia concentration of the waste water W becomes the target concentration. The required air amount calculation unit 84 calculates the required air amount for all the reaction tanks 10 and calculates the total required air amount by adding the required air amounts.

  After calculating the required air amount, the air supply amount control unit 40 calculates the target pipe internal pressure from the total required air amount by the target pipe internal pressure calculation unit 74 (step S16), and the air supply control unit 76 calculates the target pipe internal pressure. The air supply of the blower 22 is controlled so as to become (step S18). The target pipe internal pressure is the pressure of air in the blow pipe necessary for supplying the total necessary air amount. The air blow control unit 76 controls the number of air blowers 22 to be operated, the opening degree of the inlet vane of the air blower 22, and the number of rotations of the blades, and adjusts the amount of air discharged from the air blower 22 to adjust the air pressure in the mother pipe 32. Is the target pipe pressure. A specific control flow of the air blowing control unit 76 will be described later.

  In addition, after calculating the required air amount, the air supply amount control unit 40 sets the opening degree of the introduction valve 36 so that the introduction air control unit 78 supplies the necessary amount of air to each reaction tank 10. Adjust (step S20). After step S18 and step S20, the process proceeds to step S22, and when the process is not terminated (step S22: No), the process returns to step S10 and the same process is repeated. That is, the air supply amount control unit 40 measures the nitric acid concentration and the ammonia concentration of the wastewater W in each reaction tank 10 every predetermined time, updates the necessary air amount and the target pipe pressure based on the measurement results, The amount of air discharged from the blower 22 is sequentially controlled so as to achieve the updated target pipe pressure. Further, the air supply amount control unit 40 sequentially controls the opening degree of the introduction valve 36 so that the renewed required amount of air is supplied to the reaction tank 10. In addition, when the process ends in step S22 (step S22; Yes), this process ends.

  In the case of the above-described dissolved oxygen amount control, the dissolved oxygen amount in the reaction vessel 10 is calculated in step S10, and the necessary air amount is calculated in step S12 so that the dissolved oxygen amount becomes the target amount (target water quality). Other processes are the same as described above.

  Next, the control of the blower 22 by the blow control unit 76 will be described. FIG. 6 is a flowchart for explaining control of the blower by the blower control unit. FIG. 7 is a graph for explaining the control of the blower by the blower. As shown in FIG. 6, the blower control unit 76 first acquires the value of the target pipe pressure from the target pipe pressure calculation unit 74 (step S30).

The air blow control unit 76 determines whether the pipe internal pressure at the maximum output of the blower 22 is equal to or higher than the target pipe internal pressure (step S32). The maximum output of the blower 22 is an output when the outputs of all the blowers 22 are maximized in the current number of operating fans 22. Furthermore, the output when the opening degree of the inlet vane of the blower 22 is maximized and the rotation speed of the blade portion is maximized becomes the maximum output. The horizontal axis in FIG. 7 is the output value of the blower 22, and the vertical axis is the pipe internal pressure of the blower pipe 30. As shown in FIG. 7, the pipe pressure when one blower 22 is operating is the pipe pressure Pr ₁ at the maximum output. The pipe internal pressure when two blowers 22 are operating, for example, increases to the pipe internal pressure Pr ₂ at the rated output, and further increases to the pipe internal pressure Pr _{3 as the} maximum output is increased. The pipe internal pressure when three blowers 22 are operating increases, for example, to the pipe internal pressure Pr ₄ at the rated output, and further increases to the pipe internal pressure Pr _{5 as the} maximum output is increased. When the four blowers 22 are operating, the pipe internal pressure increases, for example, to the pipe internal pressure Pr ₆ at the rated output, and further increases as the maximum output is increased. In the example of FIG. 7, a case where the target pipe pressure is a value between the pipe pressure Pr ₃ and the pipe pressure Pr ₄ is described. Further, the marginal pipe internal pressure is a value larger than the target pipe internal pressure, and in the example of FIG. 7, a case where the margin pipe internal pressure is a value between the pipe internal pressure Pr ₅ and the pipe internal pressure Pr ₆ is described.

  When the pipe internal pressure at the maximum output is not equal to or higher than the target pipe internal pressure (step S32; No), that is, lower than the target pipe internal pressure, the blower control unit 76 increases the number of operating blowers 22 (step S34). In the example of FIG. 7, the pipe pressure at the maximum output when two blowers 22 are operating is lower than the target pipe pressure, and in this case, the blow control unit 76 sets the number of operating units to three. When the operating number is increased, the process returns to step S32, and it is determined whether the maximum output of the blower 22 in the increased operating number is equal to or higher than the target pipe pressure.

  When the pipe internal pressure at the maximum output is equal to or higher than the target pipe internal pressure (step S32; Yes), the blower control unit 76 determines whether the pipe internal pressure at the maximum output of the blower 22 is equal to or less than the margin pipe internal pressure (step S36). ). When the pipe internal pressure at the maximum output is equal to or less than the margin pipe internal pressure (step S36; Yes), the air blowing control unit 76 outputs the output of the operating blower 22 so as to reach the target pipe internal pressure without changing the number of operating units. Control is performed (step S38). In the example of FIG. 7, the pipe internal pressure at the maximum output when three blowers 22 are operating is equal to or higher than the target pipe internal pressure and equal to or less than the marginal pipe internal pressure. In the example of FIG. 7, when three blowers 22 are operating, the output is made smaller than the rated output by controlling the opening degree of the inlet vane and the rotational speed of the blade portion, and the pipe internal pressure becomes the target pipe internal pressure. Like that.

  If the pipe internal pressure at the maximum output is not less than or equal to the extra pipe internal pressure (step S36; No), that is, if the pipe internal pressure is higher than the extra pipe internal pressure, the number of operating fans 22 is decreased (step S40). In the example of FIG. 7, the pipe internal pressure at the maximum output when four blowers 22 are operating is lower than the surplus pipe internal pressure, and in this case, the air blow control unit 76 sets the number of operating units to three. When the number of operating units is decreased, the process proceeds to step S38, and the output of the operating blower 22 is controlled so that the target pipe pressure is reached. After step S38, the process proceeds to step S42, and when the process is not terminated (step S42; No), the process returns to step S30, and the updated target pipe pressure information is acquired and the same target pipe pressure is obtained. Repeat the process. When the process is to be ended (step S42; Yes), this process is ended.

  The wastewater treatment system 1 described above includes a plurality of reaction tanks 10 that perform biological treatment on the wastewater W, a blower pipe 30 that is a pipe connected to the plurality of reaction tanks 10, and a plurality of reactions via the blower pipes 30. It has the ventilation unit 20 which supplies the air for performing biological treatment to the tank 10, and the air supply amount control part 40 which controls the air supply amount to the reaction tank 10. FIG. The air supply amount control unit 40 includes a water quality measurement unit (in this embodiment, a nitric acid meter 43 and an ammonia meter 44), a necessary air amount acquisition unit 72, a target pipe pressure calculation unit 74, and a ventilation control unit 76. The nitric acid meter 43 and the ammonia meter 44 are provided in the reaction tank 10 and measure the state of the waste water W in the reaction tank 10 (in this embodiment, the nitric acid concentration and the ammonia concentration of the waste water W). The required air amount acquisition unit 72 is based on the measurement results of the nitric acid meter 43 and the ammonia meter 44, and the required air amount for making the waste water W in the reaction tank 10 have a predetermined target water quality (target concentration in the present embodiment) The total required air amount that is the total amount in all the reaction vessels 10 is acquired. The target pipe pressure calculation unit 74 calculates a target pipe pressure, which is the pressure of air in the blower pipe 30 necessary for supplying the total necessary air amount. The air blowing control unit 76 controls the air supply from the air blowing unit 20 so that the pressure in the air blowing pipe 30 becomes the target pipe internal pressure. This target pipe internal pressure changes according to the state of the waste water W in the reaction tank 10.

  The wastewater treatment system 1 measures the current state of the wastewater W, calculates the total necessary air amount necessary for making the wastewater W the target water quality, and the target pipe pressure necessary for supplying the necessary air amount. The blower unit 20 is controlled so that That is, the wastewater treatment system 1 controls the air supply unit 20 to supply a minimum amount of air necessary for biological treatment based on the current water quality. Therefore, the wastewater treatment system 1 can suppress supply of air unnecessary for biological treatment and suppress energy consumption required for blowing. In the wastewater treatment system 1, air blowing by the blower unit 20 occupies most of the power consumption. Therefore, by reducing the amount of air blown, the power consumption can be effectively reduced.

  Further, the target pipe pressure calculation unit 74 increases the target pipe pressure when the total required air amount increases, and decreases the target pipe pressure when the total required air amount decreases. When the total required air amount increases, for example, when the load increases, the wastewater treatment system 1 increases the target pipe pressure and reliably supplies the required amount of air, while the total required air amount decreases. For example, when the load decreases, the target pipe pressure is lowered, so that energy consumption can be reliably suppressed.

  The blower pipe 30 includes a mother pipe 32 connected to the blower unit 20, a plurality of branch pipes 34 branched from the mother pipe 32 and connected to the plurality of reaction vessels 10, and an introduction valve provided in the branch pipe 34. 36. Then, the air supply amount control unit 40 adjusts the opening degree of the introduction valve 36 based on the required air amount and the air supply amount to the branch pipe 34 so that the air supply amount to the reaction tank 10 becomes the required air amount. The introduction air control unit 78 is provided. The wastewater treatment system 1 can appropriately supply a necessary amount of air to the reaction tank 10 by the introduction air control unit 78 while suppressing supply of air unnecessary for biological treatment by the air blowing control unit 76. .

  The air blow control unit 76 controls at least one of the number of operating blowers 22, the opening degree of the inlet vane, and the rotational speed of the blade part. Therefore, the wastewater treatment system 1 can appropriately set the pipe internal pressure of the blower pipe 30 to the target pipe internal pressure.

  In addition, the water quality measurement unit, as the state of the waste water W in the reaction tank 10, the nitrate nitrogen concentration, the ammonia nitrogen concentration, the dissolved oxygen amount of the waste water W in the reaction tank 10, and the inflow of waste water into the reaction tank Measure at least one of the quantities. Therefore, the wastewater treatment system 1 can appropriately calculate the required air amount.

  The water quality measurement unit measures at least one of the nitrate nitrogen concentration, the ammonia nitrogen concentration, and the dissolved oxygen amount of the waste water W as the water quality of the waste water W in the reaction tank 10, and the necessary air amount acquisition unit 72. Calculates the required air amount so that the water quality of the waste water W becomes the target water quality. Since the wastewater treatment system 1 measures the water quality and calculates the required air amount so that the water quality becomes a target value, the required air amount can be calculated more accurately. In addition, the waste water treatment system 1 may perform simultaneous nitrification denitrification treatment. In the simultaneous nitrification / denitrification treatment, the nitrification treatment, which is an aerobic treatment, and the denitrification treatment, which is an anaerobic treatment, are performed in the same tank. The fact that the fluctuation of the required air amount becomes large means that the required air amount often decreases, so that the energy consumption can be further suppressed.

  The required air amount acquisition unit 72 includes a relationship storage unit 82 and a required air amount calculation unit 84. The relationship storage unit 82 is a relationship between the amount of air supplied to the reaction tank 10 and the amount of change in the quality of the waste water W (here, nitric acid concentration and ammonia concentration) when that amount of air is supplied. Remember the relationship. The required air amount calculation unit 84 is an air amount necessary for changing the water quality of the wastewater W to the target water quality based on the water quality air quantity relationship, the water quality measurement result by the water quality measurement unit, and the target water quality (here, the target concentration). Is calculated as the required air amount. Since the required air amount calculation unit 84 calculates the required air amount based on the water quality air amount relationship, the required air amount can be calculated more accurately.

  Further, the relationship storage unit 82 stores the water quality air quantity relationship as a first-order lag system in which the change in the quality of the waste water W is delayed with respect to the change in the amount of air supplied into the reaction tank 10. The required air amount calculation unit 84 updates the required air amount based on the water quality measurement results for each elapse of a predetermined time. Since this wastewater treatment system 1 calculates the required air amount as a first-order lag system, it can predict the amount of water quality change for each hour. Furthermore, since the wastewater treatment system 1 repeats the calculation of the required air amount and updates the calculation result, the air supply amount can be more accurately controlled based on the latest measurement result. That is, the wastewater treatment system 1 can more accurately control the air supply amount by performing feedforward control.

  As mentioned above, although embodiment and the modification of this invention were demonstrated, embodiment is not limited by the content of these embodiment etc. In addition, the above-described constituent elements include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the above-described components can be appropriately combined. Furthermore, various omissions, substitutions, or changes of the constituent elements can be made without departing from the spirit of the above-described embodiments and the like.

DESCRIPTION OF SYMBOLS 1 Wastewater treatment system 10 Reaction tank 12 Aeration part 20 Blower unit 22 Blower 30 Blower pipe 31 Introduction pipe 32 Mother pipe 34 Branch pipe 40 Air supply amount control part 42 Control part 43 Nitric acid meter 44 Ammonia meter 46 Intake measurement part 47 Mother pipe internal pressure Measurement unit 48 Branch air amount measurement unit 70 Water quality measurement result acquisition unit 72 Required air amount acquisition unit 74 Target pipe pressure calculation unit 76 Air blow control unit 78 Introduced air control unit 82 Relation storage unit 84 Required air amount calculation unit W Wastewater

Claims (10)

Multiple reactors for biological treatment of wastewater;
A blower pipe which is a pipe connected to the plurality of reaction vessels;
A blower unit that supplies air for performing the biological treatment to a plurality of the reaction tanks via the blower pipes;
An air supply amount control unit for controlling the air supply amount to the reaction tank,
The air supply amount controller
A water quality measuring unit that is provided in the reaction tank and measures the state of waste water in the reaction tank;
Based on the measurement result of the water quality measurement unit, a required air amount acquisition unit that acquires the total required air amount, which is the total amount in all reaction tanks, of the required air amount for making the wastewater in the reaction tank a predetermined target water quality; ,
A target pipe pressure calculation unit that calculates a target pipe pressure that is a pressure of air in the blow pipe necessary to supply the total required air amount;
A blower control unit that controls air supply from the blower unit such that the pressure in the blower pipe becomes the target pipe internal pressure;
Have
The target pipe internal pressure is a wastewater treatment system that changes according to the state of wastewater in the reaction tank.   2. The target pipe pressure calculation unit according to claim 1, wherein the target pipe pressure calculation unit increases the target pipe pressure when the total required air amount increases, and decreases the target pipe pressure when the total required air amount decreases. Wastewater treatment system. The blower pipe includes a mother pipe connected to the blower unit, a plurality of branch pipes branched from the mother pipe and respectively connected to the plurality of reaction vessels, and an introduction valve provided in the branch pipe. And
The air supply amount control unit adjusts the opening of the introduction valve based on the required air amount and the air supply amount to the branch pipe so that the air supply amount to the reaction tank becomes the required air amount. The wastewater treatment system according to claim 2, further comprising an introduction air control unit. The blower unit has a plurality of blowers that sucks air through inlet vanes and exhausts by rotation of blade portions,
4. The air blowing control unit according to claim 1, wherein the air blowing control unit controls at least one of an operating number of the blowers, an opening degree of the inlet vane, and a rotation speed of the blade part. 5. Wastewater treatment system.   The water quality measurement unit includes at least a nitrate nitrogen concentration, an ammonia nitrogen concentration, a dissolved oxygen amount, and an inflow amount of waste water into the reaction tank as a state of waste water in the reaction tank. The wastewater treatment system according to any one of claims 1 to 4, wherein any one of them is measured.   The water quality measurement unit measures at least one of nitrate nitrogen concentration, ammonia nitrogen concentration, and dissolved oxygen content of the waste water as water quality of the waste water in the reaction tank, and the necessary air amount acquisition unit, The wastewater treatment system according to claim 5, wherein the required amount of air is calculated so that the quality of the wastewater becomes the target water quality. The required air amount acquisition unit
A relationship storage unit that stores a relationship between the amount of air supplied to the reaction tank and the amount of change in water quality in the reaction tank when the amount of air is supplied;
Based on the water quality air quantity relationship, the water quality measurement result by the water quality measurement unit, and the target water quality, the air quantity necessary for changing the waste water quality to the target water quality is calculated as the required air quantity. The wastewater treatment system according to claim 6, further comprising: a required air amount calculation unit. The relationship storage unit stores the water / air amount relationship as a first-order lag system in which a change in the quality of the wastewater is delayed with respect to a change in the amount of air supplied into the reaction tank,
The wastewater treatment system according to claim 7, wherein the required air amount calculation unit updates the required air amount based on the water quality measurement result for each elapse of a predetermined time by the water quality measurement unit. A plurality of reaction vessels that perform biological treatment on waste water, a blower pipe that is a pipe connected to the plurality of reaction vessels, and air for performing the biological treatment on the plurality of reaction vessels via the blower tubes. An air supply amount control device for controlling an air supply amount of a wastewater treatment device having a blower unit to supply,
A water quality measuring unit that is provided in the reaction tank and measures the state of waste water in the reaction tank;
Based on the measurement result of the water quality measurement unit, a required air amount acquisition unit that acquires a total required air amount that is a total amount in all reaction tanks of a required air amount for the wastewater of the reaction tank to have a predetermined target water quality;
A target pipe pressure calculation unit that calculates a target pipe pressure that is a pressure of air in the blow pipe necessary to supply the total required air amount;
A blower control unit that controls air supply from the blower unit such that the pressure in the blower pipe becomes the target pipe internal pressure;
Have
The target pipe internal pressure changes depending on the state of waste water in the reaction tank.
Air supply control device. A plurality of reaction vessels that perform biological treatment on waste water, a blower pipe that is a pipe connected to the plurality of reaction vessels, and air for performing the biological treatment on the plurality of reaction vessels via the blower tubes. An air supply amount control method for controlling an air supply amount of a wastewater treatment device having a blowing unit to be supplied,
A measuring step for measuring the state of waste water in the reaction vessel;
Based on the measurement result of the state of the waste water, a necessary air amount acquisition step for acquiring a total required air amount that is a total amount in all the reaction tanks of a required air amount for the waste water of the reaction tank to have a predetermined target water quality;
A target pipe pressure calculating step for calculating a target pipe pressure that is a pressure of air in the blow pipe necessary to supply the total required air amount;
A ventilation control step for controlling the air supply from the blowing unit so that the pressure in the blowing pipe becomes the target pipe internal pressure;
Have
The target pipe internal pressure changes depending on the state of waste water in the reaction tank.
Air supply amount control method.

Images