JP2010269276A - Method and apparatus for controlling water treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust an aeration airflow rate and a flocculant injection ratio so as to minimize energy consumption while satisfying the target value of a phosphorus concentration in treated water, from the water quality of water to be treated and the state of a bioreactor. <P>SOLUTION: An apparatus for controlling water treatment includes the bioreactor having an anaerobic tank 4 and an aerobic tank 5, a stirring tank 7 provided with equipment for injecting a flocculant; a final sedimentation basin 8 connected to the stirring tank 7, and a computer 1. The computer 1 includes: a computing part 2 for computing the aeration airflow rate and the flocculant injection ratio so as to minimize energy consumption upon satisfying the target value of the phosphorus concentration in the treated water, from the deviation of water quality between the water to be treated and the treated water, and from the state of the bioreactor; and a control part 3 for controlling aeration equipment and the equipment 14 for injecting the flocculant on the basis of the computing results. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes an aeration facility and a flocculant injection facility, which satisfies the target value of phosphorus concentration in treated water and adjusts the amount of aeration air and the amount of flocculant injected to minimize energy consumption. The present invention relates to a water treatment control method and apparatus.

  For example, in closed waters such as lakes and inner bays where there is not much inflow and outflow of water, eutrophication has not been resolved since the high growth period, which is a serious problem. The main factor of this eutrophication is inflow of so-called nutrient salts such as nitrogen and phosphorus, and it is important for water quality conservation to reduce the inflow load of nutrient salts.

  In sewage treatment plants, organic substances are mainly removed by biological treatment using activated sludge called activated sludge method (a general term for floating organic sludge mainly composed of microorganisms). However, since sewage contains organic substances such as nitrogen and phosphorus, the removal of them is also required.

  As measures to meet such demands, several methods are known, such as dividing a microbial reaction tank, which is one facility of the activated sludge method described above, into an aerobic region and an anaerobic region.

  For example, in the activated sludge circulation method, after performing BOD oxidation and nitrification reaction in an aerobic region, the nitrification solution is sent to the anaerobic region using a circulation pump or the like to perform denitrification. Methods for improving the phosphorus removal rate include an anaerobic-aerobic method (AO method) and anaerobic-anoxic-aerobic method (A2O method). Of these, the A2O method includes not only phosphorus but also nitrogen. Improvement in removal rate is also expected.

  These methods utilize the phenomenon of excessive phosphorus intake. In the anaerobic region located in the front stage, activated sludge releases phosphorus, but in the rear stage aerobic area, it consumes more phosphorus than released. This is called an overdose phenomenon, and the concentration of phosphorus in water is reduced throughout the process.

  The phenomenon of excessive intake of activated sludge by phosphorus is likely to depend on the quality of the water to be treated and the state of the activated sludge itself, and the phosphorus concentration may not be reduced or increased due to poor release or poor intake. Therefore, a countermeasure is generally taken to adjust the phosphorus concentration in the treated water by injecting a flocculant such as a metal salt in accordance with the removal status of phosphorus.

  Conventionally, the physicochemical treatment method in the aerobic region and the subsequent stage of such a bioreactor has been used for the purpose of complementing the biological treatment utilizing the above-described phosphorus excess intake phenomenon. For this reason, it is considered desirable to minimize the usage amount, and methods for minimizing the usage amount have been considered.

  For example, in the conventional technique described in [Patent Document 1], when the phosphorus removal ability of a biological reaction tank is determined and it is predicted that the phosphorus concentration of the treated water cannot be maintained below the target value, the treated water or the treated water It has been proposed to obtain the coagulant injection rate based on the logarithmic ratio between the measured value of phosphorus concentration in water and the target value, and to control the coagulant injection facility. In the conventional technique described in [Patent Document 2], the amount of aeration air is optimally controlled in order to adjust the injection amount of the flocculant to an optimal amount.

Japanese Patent Application Laid-Open No. 11-169885 JP 2006-315004 A

  The background of the conventional water treatment control device that controls the amount of flocculant to be injected to the minimum after aeration and biological phosphorus removal is the background. And the increase in the amount of sludge associated therewith is directly linked to the cost of chemicals and sludge treatment.

  Recently, greenhouse gases and their emissions have attracted attention, and reduction of energy consumption has become an important issue. Along with this, a bold review of the prior art is required.

  In general, aeration in an aerobic tank has the largest energy consumption in the sewage treatment process, and a reduction in the amount of aeration air directly leads to a reduction in energy consumption in the entire sewage treatment process. However, it is thought that the amount of biological removal of phosphorus decreases as the aeration volume decreases, and the decrease in the amount of biological phosphorus removal is compensated by physicochemical removal, that is, the coagulant injection rate is increased. It is possible to keep the phosphorus concentration in the treated water at the same level. However, as described above, the cost of chemicals and sludge treatment increase, and the energy consumption associated with this increases.

  Such a control method and apparatus in consideration of the energy efficiency of biological treatment and physicochemical treatment in removing phosphorus has not been developed so far.

  It is an object of the present invention to calculate and control an appropriate distribution of biological treatment and physicochemical treatment so as to minimize energy consumption after satisfying the target value of phosphorus concentration in treated water. The object is to provide a processing control method and apparatus.

  In order to achieve the above object, the water treatment facility of the present invention comprises a biological reaction tank having an anaerobic tank and an aerobic tank, a stirring tank having a flocculant injection facility, a sedimentation basin, and a calculator. A calculation unit that calculates the amount of aeration air and the coagulant injection rate so that the energy consumption is minimized while satisfying the target value for the phosphorus concentration in the treated water, based on the quality of the treated water and the state of the biological reaction tank. It has a control part which controls aeration equipment and flocculant injection equipment based on a result.

  According to the present invention, it is possible to control the energy consumption to be minimized by satisfying the target value of the phosphorus concentration of the treated water and adjusting the correlation between the aeration air volume and the coagulant injection quantity.

The block diagram of the water treatment control apparatus which is one Example of this invention. The block diagram of the water treatment control apparatus using the A2O method. The block diagram of the water treatment control apparatus which does not use a stirring tank.

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram of a water treatment apparatus based on an anaerobic-aerobic method (AO method), which is provided with a control device that calculates an aeration air volume and a coagulant injection rate.

  The water treatment apparatus of this embodiment is connected to the anaerobic tank 4 into which the water to be treated flows through the water distribution pipe 20, the aerobic tank 5 connected to the anaerobic tank 4, and the aerobic tank 5 through the water distribution pipe 21. And a final sedimentation basin 8 connected to the agitation tank 7 via a water distribution pipe 22, and a computer 1 connected to a water quality meter and a control device via a signal line.

  A flow meter 15 that measures the flow rate of the water to be treated and a pre-stage water quality meter 16 that measures the phosphorus component concentration in the water to be treated are attached to the water distribution pipe 20. Here, depending on the treated water and the purification plan, a pre-stage water quality meter may be additionally attached for other water quality items such as ammonia concentration and nitrogen component concentration.

  An anaerobic tank water quality meter 18 for measuring a specific index in the anaerobic tank 4 is attached to the anaerobic tank 4. In this embodiment, ORP is used as an index, but other indexes and concentrations having a correlation with the amount of biological phosphorus removal may be used. The anaerobic tank 4 is provided with an anaerobic tank stirrer 19 for stirring the inside of the anaerobic tank 4. The aerobic tank 5 is provided with aeration equipment for aerating the inside of the aerobic tank 5. The aeration equipment includes a blower 10 (also referred to as a blower) and a diffuser tube 9.

  The agitation tank 7 is provided with a flocculant injection facility 14 for injecting a flocculant into the agitation tank 7 and an agitation tank agitator 11 for agitating the inside of the agitation tank 7. The final settling basin 8 and the anaerobic tank 4 are connected by a water pipe 24 to which a return pump 12 is attached. The final settling basin 8 is connected to a drawing pump 13 that draws excess sludge through a water distribution pipe 25. A distribution pipe 23 for discharging treated water is connected to the final sedimentation basin 8.

  In the flow meter 15, the pre-stage water quality meter 16, the anaerobic tank water quality meter 18, and the target value input unit 17, the calculation unit 2 of the computer 1 that calculates the aeration air volume and the coagulant injection rate based on the respective information includes the signal line 31, 32, 33, and 34 are connected. The control unit 3 of the computer 1 that controls the aeration air amount of the blower 10 and the coagulant injection amount of the coagulant injection facility 14 based on the calculation result of the calculation unit 2 of the computer 1 is sent to the blower 10 and the coagulant injection facility 14. The line 35 and the signal line 36 are connected.

  Since it is configured in this way, as shown in FIG. 1, the treated water is first settled and removed in a sedimentation basin (not shown), and then passed through the water distribution pipe 20 to the biological reaction tank. Inflow. Return sludge is supplied from the final sedimentation basin 8 through the water distribution pipe 24 to the anaerobic tank 4 to which the water to be treated is guided, and the water to be treated and the returned sludge are stirred and mixed by the stirring tank agitator 19.

  Since the anaerobic tank 4 is in an anaerobic state, the activated sludge hydrolyzes the polyphosphoric acid accumulated in the cells to release orthophosphoric acid (PO4-P) into the liquid, while adsorbing organic matter. Accumulate in cells. For this reason, in the anaerobic tank 4, the phosphorus concentration increases and the organic matter decreases.

  The liquid mixture in the anaerobic tank 4 is guided to the aerobic tank 5 through the partition wall. A diffuser tube 9 is installed at the bottom of the aerobic tank 5, and the mixed solution is stirred by supplying air from the blower 10 to supply oxygen to the activated sludge. Since the aerobic tank 5 is in an aerobic state, the activated sludge decomposes the adsorbed organic matter into water and carbon dioxide, and oxidizes ammonia nitrogen to nitrate or nitrite nitrogen. In addition, orthophosphoric acid in the liquid is taken into the cell as polyphosphoric acid. As described above, this phenomenon is called phosphorus excessive intake, and the intake amount in the aerobic tank 5 is usually higher than the release amount in the anaerobic tank 4. Accordingly, the phosphorous concentration in the liquid is reduced in the whole process.

  Incoming water from the aerobic tank 5 is guided to the agitation tank 7 through the water distribution pipe 21. In the agitation tank 7, the aggregating agent is injected by the aggregating agent injection facility 14, and the aggregating agent and the incoming water are mixed and agitated by the agitation tank agitator 11. The liquid mixture in the stirring tank 7 is guided to the final sedimentation tank 8 through the water distribution pipe 22. Here, solid-liquid separation is performed by gravity sedimentation of the activated sludge in the mixed liquid.

  The supernatant liquid is discharged into the river or ocean after chlorination as treated water through the water distribution pipe 23. The precipitated activated sludge is returned to the biological reaction tank by the return pump 12 via the water distribution pipe 24 as return sludge, and the surplus is discharged out of the system via the extraction pump 13 as excess sludge.

  During this time, the flow meter 15 attached to the water distribution pipe 20 measures the flow rate of the water to be treated flowing through the water distribution pipe 20 and transmits the measurement signal to the calculation unit 2 via the signal line 31. The pre-stage water quality meter 16 attached to the water distribution pipe 20 measures the phosphorus component concentration of the water to be treated flowing through the water distribution pipe 20 and transmits the measurement signal to the calculation unit 2 via the signal line 32. The anaerobic tank water quality meter 18 attached to the anaerobic tank 4 measures the ORP value in the anaerobic tank 4 and transmits the measurement signal to the calculation unit 2 via the signal line 33. The target value input unit 17 transmits the input target value to the calculation unit 2 via the signal line 34. The calculation unit 2 performs the calculation of Formula 1 based on the measurement signal from the flow meter 15 and the previous water quality meter 16 and the target value from the target value input unit 17 to calculate the phosphorus removal amount target value.

(Equation 1)
Prem = (Pqua-Ptar) · Wvol (1)
Here, Prem is the target phosphorus removal amount, Pqua is the phosphorus component concentration of the treated water, Ptar is the target phosphorus component concentration of the treated water, and Wvol is the amount of treated water.

  The calculation unit 2 calculates the aeration air amount of the blower 10 and the coagulant injection amount of the coagulant injection equipment 14 when the phosphorus removal amount target value calculated by Equation 1 is achieved, using Equations 2 to 12.

  As shown in Equation 2, the phosphorus removal amount calculation value is obtained by the sum of the removal amount by biological treatment and the removal amount by physicochemical.

(Equation 2)
Prema = Prbio + Prche (2)
Here, Prema is a calculated phosphorus removal amount, Prbio is a biological treatment amount of phosphorus, and Prche is a physicochemical treatment amount of phosphorus.

  As shown in Equation 3, the phosphorus removal amount by biological treatment is obtained by multiplying the ORP value and ORP coefficient in the anaerobic tank 4 and the aeration air volume and aeration air volume coefficient in the aerobic tank 5.

(Equation 3)
Prbio = ORP / Corp / AirC / Cairq (3)
Here, ORP is an ORP value in the anaerobic tank 4, Corp is an ORP coefficient, AirC is an aeration air volume in the anaerobic tank 4, and Cairq is an aeration air volume coefficient.

  As shown in Equation 4, the phosphorus removal amount by the physicochemical treatment is obtained by multiplying the flocculant injection amount in the stirring tank 7 by the flocculant injection coefficient.

(Equation 4)
Prche = PacC ・ Cpacq (4)
Here, PacC is a flocculant injection amount in the stirring tank 7, and Cpacq is a flocculant injection amount coefficient.

  As shown in Equation 5, the total energy consumption increase / decrease value associated with phosphorus removal is determined by the sum of the energy consumption increase / decrease value associated with biological treatment and the energy consumption increase / decrease value associated with physicochemical treatment.

(Equation 5)
ΔEtotal = ΔEbio + ΔEche (5)
Here, ΔEtotal is the total energy consumption increase / decrease value, ΔEbio is the energy consumption increase / decrease value associated with the biological treatment, and ΔEche is the energy consumption increase / decrease value associated with the physicochemical treatment.

  As shown in Equation 6, the increase / decrease value of the energy consumption accompanying the biological treatment is obtained by multiplying the difference between the control value of the aeration air volume and the standard value by the aeration energy coefficient.

(Equation 6)
ΔEbio = Caire (AirC-AirS) (6)
Here, Caire is an aeration energy coefficient, AirC is an aeration air volume control value, and AirS is an aeration air volume standard value.

  As shown in Equation 7, the energy consumption increase / decrease value associated with the physicochemical treatment is obtained by multiplying the difference between the control value of the coagulant injection amount and the standard value by the coagulant injection energy coefficient.

(Equation 7)
ΔEche = Cpace (PacC-PacS) (7)
Here, Cpace is the coagulant injection energy coefficient, PacC is the coagulant injection amount control value, and PacS is the coagulant injection amount standard value.

  The calculation unit 2 changes the aeration air amount AirC in the anaerobic tank 4 and the coagulant injection amount PacC in the agitation tank 7 to satisfy the phosphorus removal amount target value Prem obtained in Equation 1, and the total energy consumption increase / decrease value ΔEtotal is the minimum The aeration air amount AirC and the flocculant injection amount PacC are obtained. Here, the total energy consumption increase / decrease value ΔEtotal does not necessarily need to be minimized, and may be less than or equal to a preset value from the minimum value.

  As shown in Equation 8, the total cost increase / decrease value associated with phosphorus removal is determined by the sum of the cost increase / decrease value associated with biological treatment and the cost increase / decrease value associated with physicochemical treatment.

(Equation 8)
ΔCOSTtotal = ΔCOSTbio + ΔCOSTche (8)
Here, ΔCOSTtotal is a total cost increase / decrease value, ΔCOSTbio is a cost increase / decrease value associated with biological treatment, and ΔCOSTche is a cost increase / decrease value associated with physicochemical treatment.

  As shown in Equation 9, the cost increase / decrease value associated with the biological treatment is obtained by multiplying the difference between the control value of the aeration air volume and the standard value by the aeration cost coefficient.

(Equation 9)
ΔCOSTbio = Cairc (AirC-AirS) (9)
Here, Cairc is an aeration cost coefficient.

  As shown in Expression 10, the cost increase / decrease value associated with the physicochemical treatment is obtained by multiplying the difference between the control value of the coagulant injection amount and the standard value by the coagulant injection cost coefficient.

(Equation 10)
ΔCOSTche = Cpacc (PacC−PacS) (10)
Here, Cpacc is a coagulant injection energy coefficient.

  As shown in Equation 11, the energy increase / decrease value is minimized. As a result, a condition that minimizes the energy consumption is obtained.

(Equation 11)
minimize ΔEtotale (11)
At that time, as shown in Equation 12, the phosphorus removal amount calculation value must satisfy the phosphorus removal amount target value. Moreover, you may provide restrictions, such as cost, as needed.

(Equation 12)
subject to Prema ≧ Prem (12)
Thus, the aeration air amount control value and the coagulant injection amount control value calculated by the calculation unit 2 are sent to the control unit 3. The aeration air volume control value is sent from the control unit 3 to the blower 10 via the signal line 35. The blower 10 performs aeration of the aerobic tank through the aeration tube 9 based on the aeration air volume control value. The control value of the coagulant injection amount is sent from the control unit 3 to the coagulant injection facility 14 via the signal line 36. The flocculant injection facility 14 injects the flocculant into the agitation tank 7 based on the flocculant injection amount control value. As described above, the aeration air volume and the coagulant injection rate are adjusted and controlled so that the energy consumption is minimized while satisfying the target value for the phosphorus concentration in the treated water.

  In this embodiment, the target process has been described by the AO method. In addition, it can be applied to the A2O method (anaerobic-anoxic-aerobic method) as shown in FIG. In the A2O method, an anaerobic tank 6 is provided between the anaerobic tank 4 and the aerobic tank 5, and by providing the anaerobic tank 6, the sludge in the aerobic tank 5 is oxygen-free by a circulation device (not shown). The nitrite nitrogen and nitrate nitrogen returned to the tank 6 and fed into the anoxic tank 6 are reduced to nitrogen gas by nitrate respiration or nitrite respiration by denitrifying bacteria under anoxic conditions. Removed outside the system.

  In addition, as shown in FIG. 3, when stirring and mixing are sufficiently performed, the aerobic tank 5 and the final sedimentation tank 8 are connected by the distribution pipe 21 without using the stirring tank 7, and the flocculant is injected into the distribution pipe 21. The flocculant may be injected from the facility 14.

DESCRIPTION OF SYMBOLS 1 Computer 2 Calculation part 3 Control part 4 Anaerobic tank 5 Aerobic tank 6 Anoxic tank 7 Stirrer tank 8 Final sedimentation tank 9 Aeration pipe 10 Blower 11 Stirrer tank stirrer 12 Return pump 13 Pull-out pump 14 Flocculant injection equipment

Claims (3)

  An anaerobic tank into which treated water flows through the distribution pipe, a flow meter attached to the distribution pipe for measuring the flow rate of the treated water, a pre-stage water quality meter for measuring the phosphorus component concentration of the treated water, and the anaerobic tank An anaerobic tank water quality meter that measures a specific index that has a correlation with the amount of biological phosphorus removed in the anaerobic tank, an aerobic tank that is connected to the anaerobic tank and is equipped with aeration equipment, and is connected to the aerobic tank A stirrer tank in which a flocculant is injected from a flocculant injection facility and a stirrer is attached, a final sedimentation basin connected to a stirrer tank for discharging treated water, and a target value for inputting a phosphorus component concentration target value of the treated water A phosphorus removal amount target value is calculated from the input unit, the phosphorus component concentration target value of the treated water, the measured phosphorus component concentration of the treated water, and the flow rate of the treated water, and the calculated phosphorus removal amount target value Energy consumption using the specific index A calculation unit that calculates an aeration air amount and a coagulant injection amount that minimizes the amount, and controls the aeration equipment and the flocculant injection facility based on the aeration air amount and the coagulant injection amount calculated by the calculation unit. And a water treatment control device for sewage and industrial wastewater.   The said energy consumption is calculated from the energy consumption increase / decrease value accompanying the biological treatment by aeration, and the energy consumption increase / decrease value accompanying the physical treatment by a flocculant, The water treatment of the sewage and industrial wastewater of Claim 1 Control device.   The flow rate of the treated water measured by the flow meter attached to the water pipe into which the treated water flows into the anaerobic tank and the phosphorus component concentration of the treated water measured in the previous water quality system, and the target value input unit, The target phosphorus concentration of treated water discharged from the settling basin is input, and the calculation unit calculates the phosphorus component concentration target value from the treated water, the measured phosphorus concentration of the treated water, and the flow rate of the treated water. A specific index that calculates a removal target value, satisfies the calculated phosphorus removal target value, and has a correlation with the biological phosphorus removal amount in the anaerobic tank measured by the anaerobic tank water quality meter provided in the anaerobic tank Also, the aeration capacity of the aeration equipment attached to the aerobic tank connected to the anaerobic tank that minimizes the energy consumption, and the agglomeration attached to the stirring tank connected to the aerobic tank Calculate the flocculant injection amount of the agent injection equipment And, by the control unit, wherein the aeration equipment and coagulant injection water treatment method of controlling sewage and industrial waste water to control the equipment the aeration amount calculated as based on the coagulant injection amount calculating unit.

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