JP3444021B2 - Control method and control device for oxidation ditch type water treatment apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for efficiently removing nitrogen components in sewage in an oxidation ditch type water treatment device.

[0002]

[Prior Art] "Small Sewer Planning / Design Guidelines (Draft)"
As described in (Japan Sewer Association, March 1984), the Oxidation Ditch method is used at depths of 1 to
This is a method in which sewage and activated sludge are mixed and aerated in a 3 m endless water channel (ditch).

In recent years, the closed water area, which is the source of water supply, is eutrophied and the red tide and musty odorous microorganisms are frequently propagated. Therefore, it is required to remove nitrogen, which is the causative agent, of sewage.

Most nitrogen in sewage is ammoniacal nitrogen. Organic nitrogen is also included, but it is easily decomposed into ammoniacal nitrogen by activated sludge microorganisms. Ammoniacal nitrogen is oxidized to nitrite nitrogen by ammonia-oxidizing bacteria in activated sludge microorganisms under conditions in which oxygen is sufficiently dissolved. Furthermore, nitrite nitrogen is oxidized to nitrate nitrogen by nitrite-oxidizing bacteria in activated sludge microorganisms. This reaction is called nitrification reaction.

On the other hand, nitrate nitrogen is reduced to nitrogen gas by denitrifying bacteria in activated sludge microorganisms under the condition that oxygen is not dissolved. This reaction is called a denitrification reaction. Nitrogen in sewage is removed by being released into the atmosphere through a nitrification reaction, a denitrification reaction, and the like.

In the oxidation ditch method, an aerobic state in which oxygen is dissolved and an anaerobic state in which oxygen is not dissolved are formed in the ditch by adjusting the aeration strength and operating time of the aeration device. Nitrogen in sewage can be removed by combining the progressing nitrification reaction and the anaerobic denitrification reaction.

FIG. 20 is a block diagram showing an example of a conventional oxidation ditch type water treatment device. In FIG. 20, 1 is a ditch and 2 is an aeration device.
Also, a is a pipe for introducing sewage into the ditch 1, b
Is a pipe for sending the treated water from the ditch 1 to the final settling tank.

Next, the operation will be described. Sewage is introduced into the ditch 1 via the pipe a. In Ditch 1,
Oxygen required for the treatment is supplied by the aeration device 2, and the inflowing sewage and the activated sludge in the ditch 1 are mixed and stirred, and the mixed liquid is circulated in the ditch 1 by providing a flow velocity. The mixed solution in the ditch is sent to the final settling basin through the pipe b, and the supernatant water and the sludge are separated by sedimentation, and then the supernatant water is discharged to the outside of the system.

The operation manager of the water treatment device appropriately operates the aeration device 2 while referring to the treated water quality or the dissolved oxygen concentration value in the ditch.

[0010]

As described above, in the past, the operation manager operated the aeration device by relying on his or her own experience and can. However, since the flow rate and properties of general sewage, mainly domestic sewage, fluctuate significantly, it is difficult to form an aerobic condition and an anaerobic condition appropriately in the ditch according to the fluctuations and always obtain good water quality. There was a problem.

The present invention has been made to solve the above problems, and nitrogen components in sewage are always satisfactorily removed by appropriately controlling the operating time of the aeration device of the oxidation ditch type water treatment device. However, it is an object of the present invention to obtain a control method and a control device for an oxidation ditch type water treatment device that can secure good water quality.

[0012]

A method for controlling an oxidation ditch type water treatment device according to claim 1 of the present invention is
In a predetermined time range, the aerobic region length integrated value obtained by integrating the length of the region where the dissolved oxygen concentration in the oxidation ditch is higher than the standard value, and the length of the region where the dissolved oxygen concentration is lower than the standard value are integrated. The ratio with the integrated value of the anaerobic region length is calculated, and the aeration device of the Ditch is controlled so that the ratio falls within a predetermined management target range.

According to a second aspect of the present invention, there is provided a method of controlling an oxidation ditch type water treatment device, wherein the control target range of the ratio between the integrated value of aerobic region length and the integrated value of anaerobic region is 0.1 to 0.1.
It is set in the range of 10.

According to a third aspect of the present invention, there is provided a method for controlling an oxidation ditch type water treatment device, wherein the length of a region in which the dissolved oxygen concentration in the oxidation ditch is higher than a reference value is integrated within a predetermined time range. Calculate the difference between the integrated value of the air area length and the integrated value of the anaerobic area length obtained by integrating the length of the area where the dissolved oxygen concentration is lower than the reference value, and adjust the difference so that the difference is within the predetermined management target range. It controls an aeration device.

According to a fourth aspect of the present invention, there is provided a method of controlling an oxidation ditch type water treatment device, wherein a management target range of a difference between an aerobic region length integrated value and an anaerobic region length integrated value is set as a ditch per integration time of one hour. It is set in the range of -0.8 to 0.8 times the total length.

In the method for controlling an oxidation ditch type water treatment device according to a fifth aspect of the present invention, the dissolved oxygen concentration in the ditch is set to a reference value by moving the dissolved oxygen concentration meter along the flow direction of the ditch. The length of a high region or the length of a region lower than the reference value is measured.

A method for controlling an oxidation ditch type water treatment device according to claim 6 of the present invention uses the plant data of the oxidation ditch such as dissolved oxygen concentration and aeration strength at an arbitrary point in the oxidation ditch, length higher than the reference value of dissolved oxygen concentration in the ditch region, or Ru der to estimate the length of lower than the reference value region.

According to a seventh aspect of the present invention, there is provided a method of controlling an oxidation ditch type water treatment device, wherein the dissolved oxygen concentration reference value in the oxidation ditch is 0 to 2 [mg / L].
The range is set to.

The control method of the oxidation ditch type water treatment device according to the eighth aspect of the present invention uses at least one of the water temperature, pH and oxidation-reduction potential at any point in the oxidation ditch to control the target range. Is to correct.

The control method of the oxidation ditch type water treatment apparatus according to claim 9 of the present invention calculates the ratio or difference in the range of 1 to 48 hours, Ru der controls the aeration device.

According to a tenth aspect of the present invention, there is provided a control device for an oxidation ditch type water treatment device, wherein a measuring means for measuring the dissolved oxygen concentration in the ditch, and a predetermined length of a region where the dissolved oxygen concentration is higher than a reference value. A calculation means for calculating a ratio or a difference between a value integrated by time and a value obtained by integrating a length of a region where the dissolved oxygen concentration is lower than the reference value for a predetermined time, and a value calculated by the calculation means is a predetermined value. It is provided with a control means for controlling the aeration device so as to be within the management target range.

[0022]

The control method and the control device for the oxidation ditch water treatment device according to claims 1 to 6 and claim 10 are values obtained by integrating the lengths of regions in which the dissolved oxygen concentration is higher than the reference value within a predetermined time. By controlling the aeration device so that the ratio or difference between the value obtained by integrating the length of the region lower than the reference value is within the control target range, the aerobic region and the anaerobic region are appropriately formed in the ditch. , you always good to remove the nitrogen component in the sewage.

The oxidation ditch water treatment apparatus control method according to any one of claims 7 to 9 is the same as the above control methods except that the optimum value of the reference value, the correction method of the management target range, and the optimum value of the time interval for executing the calculation. shows the like.

[0024]

[Examples] For many years, the inventors have conducted a computer simulation based on a dynamic model on an operation control method for efficiently removing nitrogen and the like and stably performing advanced treatment in an oxyday-ditch type water treatment device. Repeat
I have been considering. As a result, they discovered several laws useful for controlling aeration devices of oxidation ditch type water treatment devices, and arrived at the present invention. First,
The dynamic model used in the computer simulation will be described below.

The kinetic model of the organic substance removal reaction is represented by the equation (1).
It is represented by. This can be found in the literature ("Real-Time Con
control of Activated Sludge
Process "(ASCE (EE), 1979)).
It is constructed based on the model of.

[0026]

[Equation 1]

Here, r _XS , r _XA , r _XI : production rate [mg / L · h] Y ₁ , Y ₂ : yield K _S : half-saturation constant [mg / L] K _fS : half-saturation constant XT : MLVSS (active sludge microorganism) concentration [mg / L] XS: Accumulation partial concentration of MLVSS [mg / L] XA: Active partial concentration of MLVSS [mg / L] XI: Inactive partial concentration of MLVSS [mg / L] fs: XS / XT fs ^M : Maximum value of fs S: Organic matter concentration [mg / L] R _T : Transfer coefficient [h ^-1 ] R _XA : Maximum specific growth rate [h ^-1 ] R _XI : Maximum specific mortality rate [H ^-1 ]. However, L represents liter.

Further, the kinetic model of the nitrification reaction is expressed by the equation (2).
It is represented by. This is also constructed based on the Stenstrom model described in the above document.

[0029]

[Equation 2]

Here, r _XNS , r _XNB : production rate [mg / L · h] r _SNO3 , r _SNO2 , r _SNH4 : substrate production rate by nitrification reaction [mg / L · h] XNS: nitrosomonas (Nitrosomonas) Concentration [mg / L] XNB: Nitrobacter concentration [mg / L] DO: Dissolved oxygen concentration [mg / L] μ _NS (DO), μ _NB (DO): Specific growth rate by mono (Monod) function ^{_{[h -1] μ NS M,}} μ NB M: maximum specific growth rate _{^{[h -1] D XNS, D}} XNB: specific mortality rate [h ^-1] r _HNH4: matrix production speed by organic removal reaction [mg / L · h] K _DO : Half-saturation constant [mg / L].

Further, the kinetic model of the denitrification reaction is expressed by the equation (3).
It is represented by. This is "water treatment engineering" (Gihodo Publishing, 197
6) and literature (“Biological Denit
Rification ”(Dep. of Sanit
ary Engineering Technical
Univ. of Denmark, 1972)).

R _DNO3 =-(R _HN + R _SN ) XA r _DNH4 = (0.25R _SN + 0.02R _HN Y ₃ ) XA r _DXS = -2.21R _HN XA r _DXA = (R _HN Y ₃ -2.0R _SN ) XA ・ ・ ・ ・ (3)

Here, r _DNO3 , r _DNH4 , r _DXS , r _DXA : production rate by denitrification reaction [mg / L · h] R _HN : biosynthetic denitrification rate constant [h ^-1 ] R _SN : within Raw Denitrification Rate Constant [h ^-1 ] Y ₃ : Yield.

The balance of the dissolved oxygen concentration is expressed by the equation (4).

[0035]

[Equation 3]

Here, r _HDO : oxygen consumption rate by removal of organic substances [mg / L · h] r _NDO : oxygen consumption rate by nitrification [mg / L · h] r _DO : oxygen transfer rate [mg / L · h] Y _NS , Y _NB : Yield K _L a: Overall oxygen transfer capacity coefficient [h ^-1 ] DO _s : Saturated dissolved oxygen concentration [mg / L].

The kinetic parameters were set as shown in the following table.

[0038]

[Table 1]

Further, the mixing in the ditch was approximated by a tank row model in the flow-down direction in consideration of the circulation flow as shown in FIG. 1, and the material balance between the tanks was taken.

The simulation conditions were set as shown in the following table with reference to "Development of mechanical aeration device used for oxidation ditch method (Ministry of Construction Technical Evaluation Report No. 82402)".

[0041]

[Table 2]

The characteristics of the aeration device (horizontal axis type rotor) were set as in equation (5).

[0043]

[Equation 4]

Here, OC: Oxygen supply rate per rotor 1 [m] [kg-O ₂ / m · h] NN: Oxygen supply efficiency (shaft power) [kg-O ₂ / kWh] K _L a: General Oxygen transfer capacity coefficient [h ^-1 ] q: Power consumption [kW] V _m : Average flow velocity in the pond [m / s] L: Channel length [m] φ: Ratio of input power used for propulsion power P _r : Power input Density [W / m ³ ] V _u : Rotor peripheral speed [m / s] ζ: Channel loss coefficient

First, a simulation was carried out in the case where the aeration apparatus installed in A of FIG. 1 was operated intermittently.
Combination of operating time and stop time of aeration device (horizontal axis type rotor) is 30 minutes, 30 minutes, 40 minutes, 20 minutes,
The immersion depth of the rotor blade is set to 1 in 3 ways of 50 minutes and 10 minutes.
Three types of 5 [cm], 20 [cm], and 24 [cm], and rotation speeds of 48 [rpm], 60 [rpm], and 71 [rp]
m], and a total of 27 simulations were performed.

Before explaining the results of this simulation, the concept leading to the determination of the index showing the balance between the aerobic state and the anaerobic state when one aeration apparatus is intermittently operated will be described.

FIG. 2 is a schematic diagram showing how the ratio of the aerobic region and the anaerobic region in the ditch fluctuates with time, in order to facilitate understanding. It is assumed that the combination of the operation time and the stop time of the aeration device is 30 minutes and 30 minutes. The white part in the figure shows the aerobic region and the shaded part shows the anaerobic region. As shown in FIG. 2, the aerobic region in the ditch extends from the vicinity of the aeration device along the direction of the ditch as the aeration starts, and becomes shorter as the aeration stops.

As an index for quantifying the balance of the length of the aerobic region and the length of the anaerobic region in the ditch in consideration of the time variation, the aerobic region length and the anaerobic region are set in a predetermined time range. The ratio of the integrated values of the region lengths (hereinafter referred to as aerobic / anaerobic region length integrated ratio) was determined. This index can be expressed as the following equation. Aerobic / anaerobic region length integration ratio = ∫L _aer dt / ∫L _ana dt (6) Here, La _aer : aerobic region length L _ana : anaerobic region length, and ∫ is t ₀ (integration Integration from the start time) to T _S (predetermined time range) is performed.

Although it can be said that the treated water quality can be controlled more precisely if the integrated time range is short, the "Small-scale sewer plan / design guidelines (draft)" (Japan Sewer Association, March 1984)
As described in (Mon.), the aeration time of the oxidation ditch method, that is, the hydraulic residence time is 24 to 36 hours, and the fluctuation of inflow load during the day is almost leveled in the ditch. Therefore, the operating conditions of the aeration apparatus are usually changed once a day. Taking these into consideration, the above integrated time range is 1 to
It is reasonable to set it to 48 hours.

Further, the literature value of the half-saturation constant of the dissolved oxygen concentration with respect to the nitrification rate or the denitrification rate (dissolved oxygen concentration at which 1/2 of the maximum rate is obtained) is approximately 0 to 2 [mg /
L]. Therefore, it is appropriate to select the reference value of the dissolved oxygen concentration for discriminating whether the arbitrary point of the ditch is aerobic or anaerobic from the range of 0 to 2 [mg / L].

The aerobic / anaerobic region length cumulative ratio can be simply calculated as follows. For example, in FIG. 2, the aerobic region length and the anaerobic region length are integrated every 10 minutes.

[0052]   Aerobic region length integrated value = 50 [m] x 10 [min]                     +60 [m] x 10 [min]                     +60 [m] x 10 [min]                     +20 [m] x 10 [min]                   = 1900 [m · min] ... (7)   Anaerobic region length integrated value = 10 [m] x 10 [min]                     +40 [m] x 10 [min]                     +60 [m] x 10 [min]                     +60 [m] x 10 [min]                   = 1700 [m · min] ... (8) Therefore, the aerobic / anaerobic region length integration ratio is as follows.   Aerobic / anaerobic region length integration ratio = 1900 [m · min] / 1700 [m · min]                         = 1.12 ... (9)

FIG. 3 is a graph summarizing the above simulation results using such an aerobic / anaerobic region length integration ratio. The abscissa of FIG. 3 shows the aerobic / anaerobic region length integrated ratio, and the ordinate shows the ratio of the total nitrogen concentration in the inflowing sewage to the total nitrogen concentration in the treated water, that is, the nitrogen removal rate. The integrated time range was 1 hour, and the dissolved oxygen concentration reference value was 0 [mg / L]. It can be seen from FIG. 3 that when the aerobic / anaerobic region length cumulative ratio is near 1, the nitrification treatment and the denitrification treatment proceed in a well-balanced manner, and the nitrogen removal rate becomes the maximum.

However, in detail, when the nitrification rate and denitrification rate of the activated sludge microorganisms in the ditch 1 change, the optimum value of the aerobic / anaerobic region length integration ratio changes. It is known that the nitrification rate and denitrification rate of activated sludge microorganisms change depending on various conditions such as water temperature, sewage composition, and concentration. For example, when the water temperature decreases by 10 ° C., the nitrification rate and the denitrification rate become about 1/2. Even in an actual sewage treatment facility, the nitrification rate and denitrification rate may suddenly change due to a sudden drop in water temperature due to rainfall or the inclusion of poisonous substances.

In this way, considering that the operation is carried out under changing environmental conditions and changing states of activated sludge microorganisms,
Management target range of aerobic / anaerobic region length integration ratio is 0.1-10
It is reasonable to set within the range of.

From the above, the present inventors have stated that "in order to obtain a good nitrogen removal rate in the oxidation ditch type water treatment device, the aerobic / anaerobic region length integration ratio is in the range of 0.1 to 10, preferably 1. The first law was found that "the aeration device should be operated intermittently so that it is near."

Further, instead of the aerobic / anaerobic region length integrated ratio, the difference between the integrated value of the aerobic region length and the integrated value of the anaerobic region length can be used as an index. The management target range of this indicator is defined as follows.

If the aerobic / anaerobic region length integration ratio shown in the equation (6) is R _L , then ∫L _aer dt / (∫L _aer dt + ∫L _ana dt) = R _L / (R _L +1) ∫L _ana dt / (∫L _aer dt + ∫L _ana dt) = 1 / (R _L +1) ··· (10) (∫L _aer dt + ∫L _ana dt) in the equation (10) is calculated as follows. To be ∫L _aer dt + ∫L _ana dt = ∫ (L _aer + L _ana ) dt = L _D T _S ··· (11) where L _{D is} the integrated value of the aerobic region length and the anaerobic region length depending on the total length of the ditch. The difference from the integrated value of can be expressed as follows. ∫L _aer dt−∫L _ana dt = R _L / (R _L +1) × L _D T _S −1 / (R _L +1) × L _D T _S = (R _L −1) / (R _L +1) × L _D T _S ... (12)

Therefore, assuming that the integrated time range is 1 hour,
∫L _aer dt−∫L _ana dt is about − when R _L = 0.1.
When 0.8 _{L D} and R _L = 10, it becomes about 0.8 _{L D.} That is, the first law is that “to obtain a good nitrogen removal rate in the oxidation ditch type water treatment device, the difference between the integrated value of the aerobic region length and the integrated value of the anaerobic region length is 1 hour. It is also possible to intermittently operate the aeration device so that it is in the range of -0.8 to 0.8 times the total length of the ditch, preferably around 0. "

FIG. 8 shows a conceptual diagram of an apparatus for realizing operation control reflecting this law. Note that, in FIG. 8, the same reference numerals as those in FIG. 20 denote the same or corresponding portions. Reference numeral 3 is a dissolved oxygen concentration meter, and 30 is a calculation means for calculating the ratio or difference between the integrated value of the aerobic region length and the integrated value of the anaerobic region length in the ditch.

The aerobic region length and the anaerobic region length necessary for this calculation are obtained by moving the dissolved oxygen concentration meter 3 in the dich flow direction, or by providing a plurality of dissolved oxygen concentration meters 3, or by measuring the dissolved oxygen concentration 3. It can be detected by various methods, such as estimation using plant data such as and aeration intensity. In FIG. 8, calculation is performed using the measurement value of the dissolved oxygen concentration meter 3 obtained via the signal line 3a.

Reference numeral 31 is a comparison calculation means for judging whether the calculated value of the ratio or difference between the integrated value of the aerobic region length and the integrated value of the anaerobic region length is within the control target range. The calculated value of the management index required for this comparison calculation is calculated by the calculation means 30 via the signal line 30a, and the management target range is the signal line 32.
It is obtained from the setting means 32 via a. When the management index is larger than the upper limit value of the management target range, the operating time of the aeration device 2 is shortened. Conversely, when the management index is smaller than the lower limit value of the management target range, the aeration device 2
Increase the operating time of. The above instructions are supplied from the comparison calculation means 31 to the controller 33 of the aeration apparatus 2 via the signal line 33a.

As a result, the aeration device 2 is intermittently operated so that the ratio or difference between the integrated value of the aerobic region length and the integrated value of the anaerobic region length falls within the predetermined management target range, and the first law is applied. As described above, the nitrogen component in the sewage can be satisfactorily removed.

Next, a simulation was carried out in the case where the aeration devices installed in A and D of FIG. 1 were simultaneously operated intermittently. Aeration device (horizontal axis type rotor)
Immersion depth of the rotor is 24 [cm], and rotation speed is 71 [r
pm] and set the combination of operating time and stop time to 2
5 minutes ・ 45 minutes 、 30 minutes ・ 30 minutes 、 33 minutes ・ 37 minutes 、 35
The simulation was performed as 7 minutes, 25 minutes, 40 minutes, 20 minutes, 45 minutes, 15 minutes, 50 minutes, and 10 minutes.

Before explaining the results of this simulation, the concept leading to the determination of the index showing the balance between the aerobic state and the anaerobic state when two aeration units are intermittently operated simultaneously will be described.

FIG. 4 is a graph showing the dissolved oxygen concentration distribution in the ditch when the combination of the operating time and the stopping time of the aeration device (horizontal axis type rotor) among the above seven cases is 40 minutes and 20 minutes. Is. The horizontal axis of FIG. 4 is shown in FIG.
Corresponding to A to F, and the vertical axis represents the dissolved oxygen concentration. The dissolved oxygen concentration distribution (solid line) is more uniform than the simulation result (dotted line) when one aeration device is used, which is also shown for comparison. This tendency was also observed in other cases.

Therefore, the aerobic state and the anaerobic state of the entire ditch are distinguished by the dissolved oxygen concentration at any point in the ditch,
The ratio of the total retention time of both of them in a predetermined time range (hereinafter referred to as aerobic / anaerobic retention time ratio) was set as an index showing the balance between the aerobic state and the anaerobic state.

Here, the time range for calculating the total holding time is the same as the integration time range of the aerobic / anaerobic region length integration ratio.
It is appropriate to select from the range of 1 to 48 hours. In addition, the dissolved oxygen concentration standard value for distinguishing between aerobic and anaerobic is 0-2 [mg
/ L] is appropriate.

FIG. 5 is a graph summarizing the above simulation results using such an aerobic / anaerobic retention time ratio. In FIG. 5, the horizontal axis represents the aerobic / anaerobic retention time ratio, and the vertical axis represents the nitrogen removal rate. The time range was 1 hour, and the dissolved oxygen concentration reference value was 0 [mg / L]. From FIG. 5, it is understood that when the aerobic / anaerobic retention time ratio is close to 1, the nitrification treatment and the denitrification treatment proceed in a well-balanced manner and the nitrogen removal rate becomes the maximum.

However, in detail, as described in the explanation of the first law, the optimum value of the aerobic / anaerobic retention time ratio changes when the nitrification rate and denitrification rate of the activated sludge microorganisms in the ditch 1 change. To do. Therefore, it is appropriate to set the management target range of this index within the range of 0.1 to 10.

From the above, the present inventors have stated that in order to obtain a good nitrogen removal rate in the oxidation ditch type water treatment device, the aerobic / anaerobic retention time ratio is in the range of 0.1 to 10, preferably in the vicinity of 1. It is sufficient to operate the aeration device intermittently so that

Further, as in the first law, "To obtain a good nitrogen removal rate in the oxidation ditch type water treatment device, the difference between the total aerobic retention time and the total anaerobic retention time is the operating value. -50 [minutes] to 50 [minutes] per hour
The aeration device may be intermittently operated so as to be in the range of 0, preferably near 0. Can also be said. The management target range was obtained by the same method as in formulas (10) to (12), with the time range being one hour.

FIG. 9 shows a conceptual diagram of an apparatus for realizing operation control that reflects this law. In FIG. 9, 2 and 200 are aeration devices, and 34 is a calculation means for calculating the ratio or difference between the total aerobic retention time and the total anaerobic retention time in the ditch. The aerobic retention time and anaerobic retention time required for this calculation are determined by the dissolved oxygen concentration at any point in the ditch and integrated. In FIG. 9, the measured value of the dissolved oxygen concentration meter 3 obtained via the signal line 3a is used. Reference numeral 35 is a comparison calculation means for determining whether the calculated value of the ratio or difference between the total aerobic retention time and the total anaerobic retention time is within the management target range. The calculated value of the management index required for this comparison calculation is obtained from the calculation means 34 via the signal line 34a, and the management target range is obtained from the setting means 36 via the signal line 36a. Further, the aeration devices 2 and 200 are connected to the controller 33 via the signal line 33a and the signal line 333a. Others are the same as in FIG.

As a result, the aeration devices 2 and 200 are intermittently operated so that the ratio or difference between the total aerobic retention time and the total anaerobic retention time falls within the predetermined control target range, and the second law is applied. As described above, the nitrogen component in the sewage can be satisfactorily removed. Although the number of aeration devices is two in the conceptual diagram of FIG. 9, the same effect can be obtained when three or more aeration devices are installed. Even if the number of aeration devices is one, if the dissolved oxygen concentration can be made substantially uniform in the ditch, it is possible to apply the second law and obtain the same effect. On the contrary, it is of course possible to apply the first law when the number of aeration devices is two or more.

Next, the third law will be described. 6 and 7 are graphs in which the data in FIGS. 3 and 5 are rearranged with the ratio of the concentration of ammonia nitrogen and the concentration of nitrate nitrogen in the treated water as the horizontal axis. The vertical axis represents the nitrogen removal rate.

From these figures, the nitrogen removal rate is good when the ratio of the concentration of nitrate nitrogen to the concentration of ammonia nitrogen in the treated water is 0.1 to 10, and it is maximum when the ratio is close to 1. Recognize. From this, the inventors have stated that in order to obtain a good nitrogen removal rate in the oxidation ditch type water treatment device, the ratio of the concentration of nitrate nitrogen to the concentration of ammonia nitrogen in the treated water is 0.1 to 10. Range, preferably 1
It suffices to intermittently operate the aeration device so as to be close to it. I found a third law.

Further, similar to the first law and the second law, "to obtain a good nitrogen removal rate in the oxidation ditch type water treatment device, the concentration of nitrate nitrogen and the concentration of ammonia nitrogen in the treated water are -25 [mg / L]
The aeration device may be intermittently operated in a range of 25 to 25 [mg / L], preferably near 0. Can also be said. Note that the above management target range is calculated by taking into account that the sum of the inflowing ammoniacal nitrogen concentration and the nitrate nitrogen concentration, that is, the average value of the total nitrogen concentration is 30 [mg / L], It is determined by the same method as 10) to 12).

Further, the ratio between the concentration of nitrate nitrogen and the concentration of total nitrogen in the treated water can be used as an index. The management target range of this indicator is defined as follows. When the ratio of the nitrate nitrogen concentration, ammonia nitrogen concentration in the treated water to ^{_{R N, NO 3 - -N /}} (NO 3 - -N + NH 4 + -N) = R N / (R N +1) ·· ( 13) here, NO ₃ ^- -N: nitrate nitrogen concentration NH ₄ ⁺ -N: ammonium nitrogen concentration

Therefore, the ratio of the concentration of nitrate nitrogen to the concentration of total nitrogen in the treated water is about 0.09 when R _N = 0.1, and R _N =
When it is 10, it becomes about 0.9.

By the way, when comparing the toxicity to fish and shellfish in the effluent area, ammonia nitrogen is stronger than nitrate nitrogen, and it may be considered that only the treatment for converting ammonia nitrogen in the inflow water into nitrate nitrogen is performed. To be Therefore, it is appropriate to set the control target range of the ratio between the nitrate nitrogen concentration and the total nitrogen concentration in the treated water within the range of 0.09 to 1.

Similarly, the ratio of the concentration of ammoniacal nitrogen in the treated water to the concentration of total nitrogen can be used as an index, and the management target range of this index is given by the formula (13) and the toxicity of ammoniacal nitrogen. , 0 to 0.9 is appropriate.

Example 1. An embodiment of the present invention will be described below with reference to the drawings. Figure 10
FIG. 3 is a configuration diagram showing an oxidation ditch type water treatment device according to a first embodiment using the first law. In this embodiment, the dissolved oxygen concentration distribution in the oxidation ditch is measured by a movable type dissolved oxygen concentration meter.

In FIG. 10, 3 is a dissolved oxygen concentration meter, 4 is
Is a controller for moving the dissolved oxygen concentration meter 3 along the Ditch flow direction to a point where the measured value of the dissolved oxygen concentration meter 3 matches a predetermined dissolved oxygen reference value,
The dissolved oxygen concentration meter 3 is connected via a signal line 3a, and the driving means 41 of the dissolved oxygen concentration meter 3 is connected via a signal line 4a. The driving means 41 is connected to the dissolved oxygen concentration meter 3 via the driving force transmitting means 41a. Reference numeral 42 is a track for the dissolved oxygen concentration meter 3, which is laid along the Ditch flow direction. Reference numeral 5 denotes a setting device for setting the above-mentioned dissolved oxygen concentration reference value, which is set in the range of 0 to 2 [mg / L], for example. The setting device 5 is connected to the controller 4 via a signal line 5a. Reference numeral 6 detects the distance from the rotor installation point of the dissolved oxygen concentration meter 3, that is, the length of a region where the dissolved oxygen concentration in the ditch 1 is higher than the dissolved oxygen concentration reference value (hereinafter referred to as aerobic region length). Is a detector for. The sensor unit 600 of the detector 6 is connected to the driving unit 41 via the driving force transmitting unit 41a like the dissolved oxygen concentration meter 3 and moves on the track 42. Sensor section 600
And the detector 6 are connected by a signal line 600a. Reference numeral 7 is an integrator for temporally integrating the length of the aerobic region in the ditch 1, which is connected to the detector 6 via a signal line 6a.
Reference numeral 8 denotes a calculator for calculating the length of the region where the dissolved oxygen concentration in the ditch 1 is lower than the dissolved oxygen concentration reference value (hereinafter referred to as the anaerobic region length), which is connected to the detector 6 by the signal line 6b. Has been done. Reference numeral 9 denotes an integrator for temporally integrating the length of the anaerobic region in the ditch 1, which is connected by the signal line 8a to the calculator 8
Connected with. Reference numeral 10 is a calculator for calculating the ratio of the integrated value of the aerobic region length and the integrated value of the anaerobic region length in the ditch 1, that is, the aerobic / anaerobic region length integrated ratio. And the signal line 9a is connected to the integrator 9. Reference numeral 11 denotes a setting device for setting a management target range of the aerobic / anaerobic region length integration ratio, which sets the management target range to, for example, 0.1 to 10. Reference numeral 12 denotes a comparison calculator for determining whether or not the calculated value of the aerobic / anaerobic region length integration ratio is within the control target range.
a, the setting device 11 and the signal line 11a are connected. 1
Reference numeral 3 denotes a memory circuit in which at least two or more intermittent operation schedules that define the operating time and the stopping time of the aeration apparatus 2 are ranked and stored in descending order of the operating time. It is connected. Reference numeral 14 denotes a controller for operating the aeration apparatus 2 according to the schedule selected by the comparison calculator 12 among the intermittent operation schedules stored in the storage circuit 13, and the storage circuit 13 is connected by the signal line 13a.
And the signal line 14a is connected to the aeration apparatus 2. The other parts are the same as or equivalent to those in FIG.

Next, the operation of the first embodiment will be described.
When the previous calculation of the aerobic / anaerobic region length integration ratio is completed, the driving means 41 and the driving force transmitting means 41a move the dissolved oxygen concentration meter 3 and the position sensor 600 on the track 42 along the Ditch flow direction. The controller 4 stops the driving means 41 at the point where the measured value of the dissolved oxygen concentration meter 3 matches the dissolved oxygen concentration reference value. The measured value of the dissolved oxygen concentration 3 necessary for this operation is obtained from the dissolved oxygen concentration meter 3 via the signal line 3a, and the dissolved oxygen concentration reference value is obtained from the setter 5 via the signal line 5a. Dissolved oxygen concentration meter 3
The stop position, that is, the distance from the rotor installation point is measured by the position sensor 600 and transmitted to the detector 6 via the signal line 600a. The detector 6 transmits this distance as the length of the aerobic region in the ditch 1 to the integrator 7 via the signal line 6a. The integrator 7 integrates the aerobic region length. The anaerobic region length in the ditch 1 is obtained by subtracting the aerobic region length in the ditch 1 from the total length of the ditch 1 in the arithmetic unit 8. The aerobic region length in the ditch 1 required for this calculation is obtained from the detector 6 via the signal line 6b. The length of the anaerobic region in the ditch 1 calculated by the calculator 8 is transmitted to the integrator 9 via the signal line 8a and is integrated there. The above operation is repeated until a predetermined time range (integrated time range) elapses. The integrated time range is preferably 1 hour to 48 hours as described above.

When a predetermined time range has elapsed, the calculator 10 calculates the ratio of the integrated value of the aerobic region length and the integrated value of the anaerobic region length in the ditch 1, that is, the aerobic / anaerobic region length integrated ratio. . The integrated value of the aerobic region length and the integrated value of the anaerobic region length in the ditch 1 necessary for this calculation are respectively obtained from the integrator 7 and the integrator 9 via the signal line 7a and the signal line 9a. The comparison calculator 12 determines whether or not the calculated value of the aerobic / anaerobic region length integration ratio is within the management target range.
Done in. The calculated value of the aerobic / anaerobic region length integration ratio and the management target range required for this comparison are calculated via the signal line 10a and the signal line 11a.
Each is obtained from 1.

When the calculated value of the aerobic / anaerobic region length integration ratio is larger than the upper limit value of the management target range, the schedule in which the operating time is currently operated is selected from the intermittent operation schedules stored in the memory circuit 13. Select the next shortest one. On the contrary, when the calculated value is smaller than the lower limit value of the management target range, the one with the next longest operating time is selected. If the calculated value is within the management target range, the intermittent operation schedule is not changed.

The above instructions are supplied from the comparison operation unit 12 to the controller 14 via the memory circuit 13 via the signal line 12a and the signal line 13a. Controller 14
Is signal line 1 based on the selected intermittent operation schedule.
The aeration device 2 is intermittently operated via 4a.

As a result, if the aerobic / anaerobic region length integration ratio is larger than the upper limit value of the management target range, the one having the shorter operating time than the intermittent operation schedule currently in operation is selected to set the aerobic region. Shorten it. On the contrary, if it is smaller than the lower limit value of the management target range, the schedule having the next longest operating time is selected and the aerobic region is extended. That is, even if the inflow load to the ditch 1 changes, the aeration device 2 is intermittently operated so that the aerobic / anaerobic region length integration ratio is close to 1, so as described in the first law. The nitrogen component in the inside can be always removed well.

Example 2. Another embodiment using the first law will be described with reference to the drawings.
FIG. 11 is a configuration diagram showing an oxidation ditch type water treatment device according to the second embodiment. In this embodiment, the dissolved oxygen concentration distribution in the oxidation ditch is measured with a plurality of dissolved oxygen concentration meters.

In FIG. 11, reference numerals 301 to 306 denote dissolved oxygen concentration meters, which are connected to the aerobic region length detector 6 via signal lines 301a to 306a. Others are shown in FIG.
Is the same as.

Next, the operation will be described. When the previous calculation of the aerobic / anaerobic region length integration ratio is completed, the dissolved oxygen concentration at each point of the ditch 1 is measured by the dissolved oxygen concentration meters 301 to 3
It measures by 06. These measured values are sent to the signal line 301a.
It supplies to the detector 6 through-306a, and detects the aerobic region length in the ditch 1. That is, each dissolved oxygen concentration meter 301-
The position where 306 is installed is input to the detector 6 in advance, and the aerobic region length in the ditch 1 is determined based on the position of the dissolved oxygen concentration meter that matches or is closest to the dissolved oxygen concentration reference value. To detect. Others are the same as in the first embodiment.

As a result, in addition to the effect of the first embodiment, there is an effect that the device structure of the ditch 1 is simplified because the carrying means of the dissolved oxygen concentration meter is unnecessary.

Example 3. FIG. 12: is a block diagram which shows the oxidation ditch type water treatment apparatus which concerns on Example 3 using the 1st law. In this example, the dissolved oxygen concentration distribution in the oxidation ditch is estimated by the dissolved oxygen concentration meters installed at two locations in the ditch.

In FIG. 12, 301 and 302 are dissolved oxygen concentration meters, which are connected via signal lines 301a and 302a to a computing unit 60 for estimating the aerobic region length. Others are the same as in FIG.

Next, the operation of the third embodiment will be described.
When the previous calculation of the aerobic / anaerobic region length integration ratio is completed, the dissolved oxygen concentration at each point of the ditch 1 is measured by the dissolved oxygen concentration meters 301 and 302. These measured values are supplied to the computing unit 60 via the signal lines 301a and 302a. The calculator 60 estimates the aerobic region length in the ditch 1 according to the following equation, for example.

L _aer = (DO ₁ −DO _thr ) / (DO ₁ −DO ₂ ) × L ₁₂ + L ₀ (14) Here, La _{aer is the} length of the aerobic region in the ditch 1, L _{12 is} dissolved. Oxygen concentration meter 301 and dissolved oxygen concentration meter 30
Distance between the two DO ₁ : measured value of the dissolved oxygen concentration meter 301 DO ₂ : measured value of the dissolved oxygen concentration meter 302 DO _thr : dissolved oxygen concentration reference value L ₀ : distance from the rotor installation position to the dissolved oxygen concentration meter 301 Is. Hereinafter, the operation is similar to that of the first embodiment.

As a result, in addition to the effect of the second embodiment, it is sufficient to install the dissolved oxygen concentration meter at two places, and therefore, there is an effect that the apparatus structure is simplified.

Example 4. FIG. 13: is a block diagram which shows the oxidation ditch type water treatment apparatus which concerns on Example 4 using the 1st law. In this example, the dissolved oxygen concentration distribution in the oxidation ditch is estimated from the measured value of a dissolved oxygen concentration meter installed at one location in the ditch and other plant data, for example, aeration intensity (oxygen supply rate).

In FIG. 13, reference numeral 61 is an arithmetic unit for estimating the length of the aerobic region in the ditch 1 from the measured value of the dissolved oxygen concentration and the aeration intensity, and via the dissolved oxygen concentration meter 3 and the signal line 3a, It is also connected to the aeration device 2 via a signal line 2a. Others are the same as in FIG.

Next, the operation will be described. When the previous calculation of the aerobic / anaerobic region length integration ratio is completed, the dissolved oxygen concentration in the ditch 1 is measured by the dissolved oxygen concentration meter 3. The aerobic region length in the ditch 1 is estimated using this measured value and the aeration intensity. Such estimation is performed by applying a state estimation method such as a Kalman filter,
It can be done easily. The subsequent operation is similar to that of the third embodiment.

As a result, in addition to the effects of the third embodiment, it suffices to install a dissolved oxygen concentration meter in only one place, so that the device structure can be further simplified.

Example 5. FIG. 14: is a block diagram which shows the oxidation ditch type water treatment apparatus which concerns on Example 5 using the 1st law. In this embodiment, the control target range of the aerobic / anaerobic region length integration ratio is corrected by the water temperature in the ditch 1.

In FIG. 14, reference numeral 15 is a thermometer for measuring the water temperature in the ditch 1. Reference numeral 16 denotes a correction circuit for correcting the management target range of the aerobic / anaerobic region length integration ratio, which includes the thermometer 15 and the signal line 11 via the signal line 15a.
A setter 11 for setting the control target range of the aerobic / anaerobic region length integration ratio via a, and the calculated value of the aerobic / anaerobic region length integration ratio within the management target range via the signal line 16a. It is connected to the comparison calculator 12 for determining whether or not there is any. Others are the same as in FIG.

Next, the operation of the fifth embodiment will be described. As described in the explanation of the first law, the nitrogen removal rate can be maximized by intermittently operating the aeration device so that the aerobic / anaerobic region length integration ratio is close to 1, but in detail, If the nitrification rate and denitrification rate of the activated sludge microorganisms in the ditch 1 change, the optimum value of the aerobic / anaerobic region length integration ratio changes. That is, when the nitrification rate is higher than the denitrification rate, more anaerobic region length is required, and conversely, when the nitrification rate is less than the denitrification rate, more aerobic region length is required. Therefore, the correction circuit 16 corrects the upper limit value and the lower limit value of the management target range of the aerobic / anaerobic region length integration ratio, for example, according to the equation (15). X _UT = X _U20 × K _D θ _D ^T-20 / K _N θ _N ^T-20 X _LT = X _L20 × K _D θ _D ^T-20 / K _N θ _N ^T-20 ··· (15) Here X _UT : Upper limit of control target range of aerobic / anaerobic region length integration ratio at water temperature T ° C X _LT : Lower limit of management target range of aerobic / anaerobic region length integration ratio at water temperature T ° C X _U20: the upper limit value of the management target range of aerobic / anaerobic region length integration ratio at a temperature 20 ° C. X _L20: lower limit K _D of the management target range of aerobic / anaerobic region length integration ratio at a temperature 20 ° C. : Denitrification rate at a water temperature of 20 ° C. θ _D : Constant K _N : Nitrification rate at a water temperature of 20 ° C. θ _N : Constant T: Temperature.

The water temperature in the ditch 1 required for this calculation is measured by the thermometer 15 and supplied to the correction circuit 16 via the signal line 15a. The upper and lower limits of the management target range of the corrected aerobic / anaerobic region length integration ratio are the signal line 1
It is supplied to the comparison calculator 12 via 6a. The subsequent operation is similar to that of the first embodiment.

Thus, when the nitrification rate is higher than the denitrification rate, the upper and lower limits of the control target range of the aerobic / anaerobic region length integration ratio are corrected to be small, and a larger anaerobic region length is secured. You can On the contrary, when the nitrification rate is smaller than the denitrification rate, the upper and lower limits of the management target range of the aerobic / anaerobic region length integration ratio are largely corrected,
More aerobic region length can be secured. That is, in addition to the effect of the first embodiment, there is an effect that the intermittent operation schedule of the aeration device 2 can be controlled more precisely.

In the fifth embodiment, the dissolved oxygen concentration distribution in the ditch 1 is measured by the movable dissolved oxygen concentration meter to calculate the aerobic / anaerobic region length integration ratio, whereas the water temperature in the ditch 1 is calculated. Although the example of correcting the management target range of the aerobic / anaerobic region length integration ratio by the above is shown, the dissolved oxygen concentration in the ditch 1 is measured by a plurality of dissolved oxygen concentration meters as in the second embodiment, and the aerobic / anaerobic condition is obtained. One for calculating the region length integration ratio, or one for calculating the aerobic / anaerobic region length integration ratio by estimating the dissolved oxygen concentration distribution in the ditch 1 with two dissolved oxygen concentration meters as in Example 3, or implementing As in Example 4, the dissolved oxygen concentration distribution in Ditch1 is estimated from the measured value of the dissolved oxygen concentration meter installed at one location in the ditch and other plant data, and the aerobic / anaerobic region length integration ratio is calculated. , In Ditch 1 Be corrected management target range of aerobic / anaerobic region length accumulation ratio by the water temperature, the same effects as in Example 5. In these device configurations, as in FIG. 14, the thermometer 15 for measuring the water temperature in the ditch 1 is connected to the correction circuit 16 via the signal line 15a, and the correction circuit 16 is connected to the comparison arithmetic unit via the signal line 16a. You can connect to 12.

As a result, in addition to the effects of the respective embodiments, there is an effect that the intermittent operation schedule of the aeration device 2 can be controlled more precisely.

In the above embodiment, the example in which the control target range of the aerobic / anaerobic region length integration ratio is corrected by the water temperature in the ditch 1 has been shown. Even if the management target range of the aerobic / anaerobic region length integration ratio is corrected by the combination of the measured values of 1, the same effect is obtained. That is, as shown in equation (15), the redox potential that affects the nitrification rate and the denitrification rate, or p
It suffices to formulate the dependency of H into a mathematical expression and incorporate it into the correction circuit 16.

Example 6. In Example 5, an example was shown in which the control target range of the aerobic / anaerobic region length integration ratio was corrected using the water temperature, redox potential, pH, etc. in Ditch 1, but nitrification of the activated sludge microorganisms in Ditch 1 was shown. The speed and the denitrification speed may be measured or estimated and supplied to the correction circuit 16. In this case, the device configuration is the same as that in FIG. 14, but the correction circuit 16 corrects the upper limit value and the lower limit value of the management target range of the aerobic / anaerobic region length integration ratio according to, for example, equation (16). The _{X U = X U0 × K D} / K N X L = X L0 × K D / K N ···· (16) wherein, X _U: management target range aerobic / anaerobic region length accumulation ratio after correction Upper limit value X _L : Lower limit value of management target range of corrected aerobic / anaerobic region length integration ratio X _U0 : Reference value of management target range upper limit value X _L0 : Reference value of management target range lower limit value K _D : Deletion Nitrification rate K _N : Nitrification rate.

As a result, when the nitrification rate is higher than the denitrification rate, the upper and lower limits of the control target range of the aerobic / anaerobic region length integration ratio are corrected to be small, and a larger anaerobic region length is secured. You can On the contrary, when the nitrification rate is smaller than the denitrification rate, the upper and lower limits of the management target range of the aerobic / anaerobic region length integration ratio are largely corrected,
More aerobic region length can be secured. That is, the same effect as that of the fifth embodiment is obtained.

Example 7. In addition, in the above-mentioned Examples 1 to 6, an example in which the intermittent operation schedule is changed using the value obtained by dividing the integrated value of the aerobic region length by the integrated value of the anaerobic region length as an index is shown. That is, even if the intermittent operation schedule of the aeration device 2 is changed using the value obtained by dividing the integrated value of the anaerobic region length by the integrated value of the aerobic region length as an index, the same effect can be obtained.

Example 8. In Examples 1 to 7, an example was shown in which the intermittent operation schedule was changed using a value obtained by dividing the integrated value of the aerobic region length by the integrated value of the anaerobic region length or its reciprocal as an index. Even if the intermittent operation schedule of the aeration apparatus 2 is changed using the difference between the integrated value of the air region length and the integrated value of the anaerobic region length as an index, the same effect is obtained.

The device configuration is the same as that of each embodiment. The difference between the integrated value of the aerobic region length and the integrated value of the anaerobic region length is calculated in the calculator 10, and this value and the management target range set in the setter 11 (in this case, the total length of the ditch per one hour of the integration time). (Set in the range of -0.8 to 0.8 times) is compared by the comparison calculator 12. When the calculated difference value is larger than the upper limit value of the management target range, the intermittent operation schedule stored in the storage circuit 13 is selected to have the shortest operating time next to the schedule currently in operation. On the contrary, when the calculated value is smaller than the lower limit value of the management target range, the one with the next longest operating time is selected. If the calculated value is within the management target range of, the intermittent operation schedule is not changed.

As a result, the integrated value of the aerobic region length and the integrated value of the anaerobic region length become equal, that is, the aerobic / anaerobic region length integrated ratio is 1 even if the inflow load to the ditch 1 changes. Since the aeration device 2 is intermittently operated so as to be in the vicinity, the same effects as those of the first to eighth embodiments are obtained.

Note that, instead of the value obtained by subtracting the integrated value of the anaerobic region length from the integrated value of the aerobic region length, the value obtained by subtracting the integrated value of the aerobic region length from the integrated value of the anaerobic region length is used as an index. Even if the intermittent operation schedule of 2 is changed, the same effect can be obtained.

Example 9. In Examples 1 to 8, the example in which the anaerobic region length is calculated after detecting or estimating the aerobic region length is shown, but the aerobic region length is calculated after detecting or estimating the anaerobic region length, Alternatively, a method of detecting or estimating the aerobic region length and the anaerobic region length at the same time has the same effect.

Further, in the above-mentioned Examples 1 to 9, the case where one aeration device was installed was described, but the number of aeration devices is not limited to this.
The same effect is obtained when two or more units are installed.

Reference Example 1 Next, a reference example using the second law will be described with reference to the drawings. 15: is a block diagram which shows the oxidation ditch type water treatment apparatus which concerns on the reference example 1. FIG. In FIG. 15, 6
2 is a dissolved oxygen concentration reference value in which the dissolved oxygen concentration at an arbitrary point in the ditch 1 is predetermined (as in Example 1, 0 to 2 [m
g / L] range) and an integrated time meter for measuring a total time (hereinafter referred to as aerobic retention time) higher than the range of [g / L]. Line 5a
Connected by. Reference numeral 80 denotes an arithmetic unit for calculating the total time (hereinafter, referred to as anaerobic retention time) when the dissolved oxygen concentration in the ditch 1 is lower than the predetermined dissolved oxygen concentration reference value, and an integrated time meter 62 and a signal It is connected by the line 62b. 100 is the ratio of aerobic retention time and anaerobic retention time,
That is, it is a computing unit for computing the aerobic / anaerobic holding time ratio, and the signal line 62a is used for the integration time meter 62 and the signal line 80.
It is connected to the calculator 80 at a. Reference numeral 110 denotes a setting device for setting a management target range of the aerobic / anaerobic retention time ratio, and the management target range is set to a range of 0.1-10. Reference numeral 120 denotes a comparison calculator for determining whether or not the calculated value of the aerobic / anaerobic retention time ratio is within the control target range. The comparator 100 is the signal line 100a, and the setter 110 is the signal line 110a. , Intermittent operation schedule memory circuit 1
3 and the signal line 120a. The storage circuit 13 is connected to the controller 14 via a signal line 13a, and further connected to the aeration apparatus 2 via a signal line 14a. Further, it is connected to the controller 140 via the signal line 13b, and further connected to the aeration apparatus 200 via the signal line 140a. Others are the same as in FIG.

Next, the operation of Reference Example 1 will be described. When the previous calculation of the aerobic / anaerobic retention time ratio is completed, the dissolved oxygen concentration in the ditch 1 is measured by the dissolved oxygen concentration meter 3. The measured value of the dissolved oxygen concentration meter 3 is compared with a predetermined dissolved oxygen concentration reference value, and if the measured value is larger, it is regarded as aerobic retention time, and this is integrated by the integration time meter 62. The dissolved oxygen concentration of the ditch 1 necessary for this integration is obtained from the dissolved oxygen concentration meter 3 via the signal line 3a, and the dissolved oxygen concentration reference value is obtained from the setter 5 via the signal line 5a.
When the predetermined time range within the range of 1 to 48 hours is completed, the anaerobic retention time in the ditch 1 is calculated by the calculator 80, for example, by subtracting the aerobic retention time from the time range. The aerobic retention time in the ditch 1 required for this calculation is obtained from the integration time meter 62 via the signal line 62b. The aerobic / anaerobic retention time ratio is calculated by the calculator 100. The aerobic retention time and anaerobic retention time in the ditch 1 necessary for this calculation are the signal line 62a and the signal line 80.
It is obtained from the integrated time meter 62 and the calculator 80 via a. The comparison calculator 120 determines whether the calculated value of the aerobic / anaerobic retention time ratio is within the management target range.
Done in. The calculated value of the aerobic / holding time ratio and the management target range necessary for this comparison are calculated via the signal line 100a and the signal line 110a.
Each is obtained from 10. When the calculated value of the aerobic / anaerobic retention time ratio is larger than the upper limit value of the management target range, the operating time is the shortest next to the currently operated schedule from the intermittent operation schedules stored in the storage circuit 13. Select one. On the contrary, when the calculated value is smaller than the lower limit value of the management target range, the one with the next longest operating time is selected. If the calculated value is within the management target range, the intermittent operation schedule is not changed.

The above instructions are supplied to the controller 14 and the controller 140 via the memory circuit 13 and the signal lines 13a and 13b. Controller 1
4 and controller 140 through the signal lines 14a and 140a based on the selected intermittent operation schedule.
Run 0 intermittently.

As a result, if the aerobic / anaerobic retention time ratio is larger than the upper limit value of the management target range, the one having the shortest operating time next to the intermittent operation schedule currently in operation is selected to set the aerobic retention time. Shorten it. Conversely, the lower limit value is 0.1
If it is smaller than the above, the schedule having the next longest operating time is selected to extend the aerobic retention time. That is, since the aeration device 2 and the aeration device 200 are intermittently operated so that the aerobic / anaerobic retention time ratio is close to 1 even if the load on the ditch 1 changes, etc., the second law is described. Thus, the nitrogen component in the sewage can always be removed well.

Reference Example 2 FIG. 16: is a block diagram which shows the oxidation ditch type water treatment apparatus which concerns on the reference example 2 using the 2nd law. this
In the reference example , the management target range of the aerobic / anaerobic retention time ratio is corrected by the water temperature in the ditch 1.

In FIG. 16, reference numeral 15 is a thermometer for measuring the water temperature in the ditch 1. Reference numeral 160 denotes a correction circuit for correcting the management target range of the aerobic / anaerobic retention time ratio, which includes the thermometer 15 and the signal line 11 via the signal line 15a.
A setting device 110 for setting a control target range of the aerobic / anaerobic region length integration ratio via 0a, and a signal line 160a.
Is connected to the comparison calculator 120 for determining whether the calculated value of the aerobic / anaerobic retention time ratio is within the control target range. Others are the same as in FIG.

Next, the operation of the reference example 2 will be described.
In the correction circuit 160, the aerobic /
Correct the upper and lower limits of the anaerobic retention time ratio. Y _UT = Y _U20 × K _D θ _D ^T-20 / K _N θ _N ^T-20 Y _LT = Y _L20 × K _D θ _D ^T-20 / K _N θ _N ^T-20 ··· (17) Here In addition, Y _UT : Upper limit value of control target range of aerobic / anaerobic retention time ratio at water temperature T ° C. Y _LT : Lower limit value of control target range of aerobic / anaerobic retention time ratio at water temperature T ° C. Y _U20 : the upper limit value Y of the management target range of aerobic / anaerobic retention time ratio when the water temperature 20 ° C. _L20: lower limit K _D of the management target range of aerobic / anaerobic retention time ratio when the water temperature 20 ° C. - water temperature 20 ° C. Denitrification rate θ _D : constant K _N : nitrification rate at a water temperature of 20 ° C. θ _N : constant T: temperature.

The water temperature in the ditch 1 necessary for this calculation is measured by the thermometer 15 and supplied to the correction circuit 160 via the signal line 15a. The upper and lower limits of the management target range of the corrected aerobic / anaerobic retention time ratio are the signal line 1
It is set in the comparison calculator 120 via 60a. The following operation is the same as that of the reference example 1 .

As a result, when the nitrification rate is higher than the denitrification rate, the upper and lower limits of the control target range of the aerobic / anaerobic retention time ratio are corrected to be small, and a longer anaerobic retention time can be secured. it can. On the contrary, when the nitrification rate is smaller than the denitrification rate, the upper limit value and the lower limit value of the management target range of the aerobic / anaerobic retention time ratio are largely corrected, and more aerobic retention time can be secured. That is, in addition to the effect of the reference example 1 , there is an effect that the intermittent operation schedule of the aeration devices 2 and 200 can be controlled more precisely.

In the above reference example , the control target range of the aerobic / anaerobic retention time ratio is corrected by the water temperature in the ditch 1, but the redox potential in the ditch 1 or p
H or aerobic due to the combination of these measured values
Even if the management target range of the anaerobic retention time ratio is corrected, the same effect can be obtained.

Reference Example 3 In Reference Example 2 , water temperature in the ditch 1, redox potential, p
Although an example in which the control target range of the aerobic / anaerobic retention time ratio is corrected using H etc. is shown, the nitrification rate and denitrification rate of the activated sludge microorganisms in the ditch 1 are measured or estimated,
It may be supplied to the correction circuit 160. In this case, the device configuration is the same as in FIG. 16, but the correction circuit 160
Then, for example, the upper limit value and the lower limit value of the management target range of the aerobic / anaerobic retention time ratio are corrected according to Expression (18). Y _U = Y _U0 × K _D / K _N Y _L = Y _L0 × K _D / K _N ... (18) Here, Y _U : Corrected aerobic / anaerobic retention time ratio management target range Upper limit value Y _L : Lower limit value of control target range of corrected aerobic / anaerobic retention time ratio Y _U0 : Reference value of upper limit value of management target range Y _L0 : Reference value of lower limit value of management target range K _D : Denitrification speed K _N : Nitrification rate.

As a result, when the nitrification rate is higher than the denitrification rate, the upper limit value and the lower limit value of the control target range of the aerobic / anaerobic retention time ratio are corrected to be small, and a longer anaerobic retention time can be secured. it can. On the contrary, when the nitrification rate is smaller than the denitrification rate, the upper limit value and the lower limit value of the management target range of the aerobic / anaerobic retention time ratio are largely corrected, and more aerobic retention time can be secured. That is, the same effect as in Reference Example 2 is obtained.

Reference Example 4 Reference Examples 1 to 3 show examples in which the intermittent operation schedule of the aeration device 2 and the aeration device 200 is changed using the value obtained by dividing the aerobic retention time by the anaerobic retention time as an index. Even if the intermittent operation schedule of the aeration device is changed using the value obtained by dividing by as the index, the same effect can be obtained.

Reference Example 5 : Reference Examples 1 to 4 show examples in which the intermittent operation schedule of the aeration device is changed using the value obtained by dividing the aerobic retention time by the anaerobic retention time or the reciprocal thereof as an index, but the aerobic retention time and the anaerobic retention time are shown. Even if the intermittent operation schedule of the aeration device is changed by using the difference between and as an index, the same effect is obtained.

The device configuration is the same as that of each reference example . The difference between the aerobic retention time and the anaerobic retention time is calculated in the calculator 100, and this value and the management target range set in the setter 110 (in this case, −50 per hour of operation time).
The range of [minute] to 50 [minute] is compared by the comparison calculator 120. When the calculated difference value is larger than the upper limit value of the management target range, the intermittent operation schedule stored in the storage circuit 13 is selected to have the shortest operating time next to the schedule currently in operation. On the contrary, when the calculated value is smaller than the lower limit value of the management target range, the one having the next longest operating time is selected. If the calculated value is within the management target range, the intermittent operation schedule is not changed.

As a result, even if the inflow load into the ditch 1 changes, the aerobic holding time and the anaerobic holding time become equal, that is, the aerobic / anaerobic holding time ratio becomes close to 1. because 2 is intermittently operated, ginseng
The same effects as those of Consideration 1 to Reference 4 are obtained.

Even if the intermittent operation schedule of the aeration device is changed using the value obtained by subtracting the aerobic retention time from the anaerobic retention time as an index instead of the value obtained by subtracting the anaerobic retention time from the aerobic retention time, the same is true Produce the effect of.

Reference Example 6 In Reference Example 1 to Reference Example 5 , an example is shown in which the anaerobic retention time is calculated after integrating the aerobic retention time. However, the aerobic retention time is calculated after integrating the anaerobic retention time, or the aerobic retention time is calculated. The same effect can be obtained by the method of integrating the time and the anaerobic retention time at the same time.

Further, in Reference Examples 1 to 5 , the case where two aeration devices were installed was described, but the number of aeration devices is not limited to this, and when one to three or more devices are installed. Also has the same effect.

Reference Example 7 : Next, a reference example using the third law will be described with reference to the drawings.
FIG. 17 is a configuration diagram showing an oxidation ditch type water treatment device according to Reference Example 7 . In this reference example , the intermittent operation schedule of the aeration apparatus is changed using the ratio of the nitrate nitrogen concentration and the ammonia nitrogen concentration as an index.

In FIG. 17, 17 is a nitrate nitrogen concentration meter for measuring the concentration of nitrate nitrogen in the treated water from the ditch 1, and 18 is also a meter for measuring the concentration of ammonia nitrogen in the treated water from the ditch 1. Ammonia nitrogen concentration meters, each of which is installed in a pipe b for sending the treated water from the ditch 1 to the final settling tank. Reference numeral 101 is a calculator for calculating the ratio between the nitrate nitrogen concentration and the ammonia nitrogen concentration. The signal line 18a is an ammonia nitrogen concentration meter 18 and the signal line 17a is a nitrate nitrogen concentration meter 17.
Connected with. Reference numeral 111 denotes a setting device for setting a control target range of the concentration ratio, and the control target range is 0.1 to 1
It is set to the range of 0. Reference numeral 121 denotes a comparison arithmetic unit for determining whether or not the calculated value of the concentration ratio is within the management target range. The arithmetic unit 101 and the signal line 101a, the setter 111 and the signal line 111a are used for the intermittent operation schedule. And the memory circuit 13 of FIG. Others are the same as in FIG.

Next, the operation of the reference example 7 will be described.
The nitrate nitrogen concentration in the treated water from the ditch 1 is measured by the nitrate nitrogen concentration meter 17, and the ammonia nitrogen concentration is measured by the ammonia nitrogen concentration meter 18. Next, the calculator 101 calculates the ratio between the nitrate nitrogen concentration and the ammonia nitrogen concentration.
Calculate by The nitrate nitrogen concentration and the ammonia nitrogen concentration in the treated water from the ditch 1 necessary for this calculation are obtained from the nitrate nitrogen concentration meter 17 and the ammonia nitrogen concentration meter 18 via the signal line 17a and the signal line 18a, respectively. . The comparison calculator 121 determines whether the calculated value of the concentration ratio is within the management target range. The calculated value of the concentration ratio and the management target range necessary for this comparison are obtained from the arithmetic unit 101 and the setting unit 111 via the signal line 101a and the signal line 111a, respectively.

When the calculated value of the concentration ratio is larger than the upper limit value of the management target range, the one having the shortest operating time out of the intermittent operation schedules stored in the memory circuit 13 is the schedule currently in operation. Select. vice versa,
When the calculated value is smaller than the lower limit of the management target range, the one with the next longest operating time is selected. If the calculated value is within the management target range, the intermittent operation schedule is not changed. Others are the same as in the first embodiment.

As a result, if the ratio of the concentration of nitrate nitrogen to the concentration of ammonia nitrogen is larger than the upper limit value of the management target range, the one having the shortest operating time next to the intermittent operation schedule currently in operation is selected, Suppress nitrification and promote denitrification. On the contrary, if it is smaller than the lower limit of the management target range, the schedule with the next longest operating time is selected to promote the nitrification treatment and suppress the denitrification treatment. That is, since the aeration device 2 is intermittently operated so that the ratio of the nitrate nitrogen concentration to the ammonia nitrogen concentration is close to 1 even if the inflow load to the ditch 1 changes, the third law is used. As described above, the nitrogen component in the sewage can always be removed well.

In the above-mentioned reference example , the intermittent operation schedule was changed by using the value obtained by dividing the nitrate nitrogen concentration by the ammonia nitrogen concentration as an index. Aeration device 2 with the value divided by the nitrogen concentration as an index
The same effect can be obtained even if the intermittent operation schedule is changed.

Reference Example 8 : In Reference Example 7 , an example was shown in which the intermittent operation schedule was changed using the value obtained by dividing the nitrate nitrogen concentration by the ammonia nitrogen concentration, or the reciprocal thereof as an index. However, the nitrate nitrogen concentration and the ammonia nitrogen concentration were changed. Even if the intermittent operation schedule of the aeration device 2 is changed using the difference between the above and the index as an index, the same effect can be obtained.

The device configuration is the same as in Reference Example 7 . The calculator 101 calculates the difference between the nitrate nitrogen concentration and the ammonia nitrogen concentration, and the comparison calculator 121 compares this value with the management target range set in the setter 111. The calculated value of the difference is the management target range (in this case, -25 [mg / L]
When the value is larger than the upper limit value of the range (~ 25 [mg / L]), the intermittent operation schedule stored in the memory circuit 13 is selected to have the next shorter operating time than the currently operating schedule. To do. On the contrary, when the calculated value is smaller than the lower limit value of the management target range, the one with the next longest operating time is selected. If the calculated value is within the management target range, the intermittent operation schedule is not changed.

As a result, even if the inflow load to the ditch 1 changes, the nitrate nitrogen concentration and the ammonia nitrogen concentration become equal, that is, the difference between the nitrate nitrogen concentration and the ammonia nitrogen concentration is near zero. Since the aeration device 2 is intermittently operated so that the same effect as in Reference Example 7 is obtained.

Reference Example 9 : In Reference Example 7 and Reference Example 8 , the positional relationship between the nitrate nitrogen concentration meter 17 and the ammonia nitrogen concentration meter 18 is shown in FIG.
The number is not limited to 7, and may be set at any point on the pipe b. Also, the same effect can be obtained by installing it at any point in the ditch 1, any point in the final settling tank, or a pipe for discharging the treated water from the final settling value.

Further, in Reference Examples 7 and 8 ,
An example using the nitrate nitrogen concentration meter 17 and the ammonia nitrogen concentration meter 18 was shown, but the nitrate nitrogen concentration and the ammonia nitrogen concentration were obtained by measurement by manual analysis or estimation from plant data, and calculated directly. Even if it is supplied to the container 101, the same effect can be obtained.

Reference Example 10 FIG. 18: is a block diagram which shows the oxidation ditch type water treatment apparatus which concerns on the reference example 10 using the 3rd law. In this reference example , the intermittent operation schedule of the aeration device is changed using the ratio of the nitrate nitrogen concentration and the total nitrogen concentration as an index.

In FIG. 18, 17 is a nitrate nitrogen concentration meter for measuring the nitrate nitrogen concentration in the treated water from the ditch 1, and 19 is the total nitrogen concentration in the treated water from the ditch 1, that is, the nitrate nitrogen concentration. And a total nitrogen concentration meter for measuring the sum of ammonia nitrogen concentrations, each of which is installed in a pipe b for sending the treated water from the ditch 1 to the final settling tank. Reference numeral 102 denotes a calculator for calculating the ratio of the nitrate nitrogen concentration and the total nitrogen concentration, and the signal line 1
9a is connected to the total nitrogen concentration meter 19 and the signal line 17a is connected to the nitrate nitrogen concentration meter 17. Reference numeral 112 denotes a setter for setting the management target range of the density ratio, and the management target range is set to the range of 0.09 to 1.0. Reference numeral 122 denotes a comparison calculator for determining whether or not the calculated value of the concentration ratio is within the management target range, and the calculator 102 and the signal line 1
02a, the setting device 112 is connected to the signal line 112a, and the intermittent operation schedule storage circuit 13 is connected to the signal line 122a. Others are the same as in FIG.

Next, the operation of the reference example 10 will be described. The nitrate nitrogen concentration in the treated water from the ditch 1 is measured by the nitrate nitrogen concentration meter 17, and the total nitrogen concentration is measured by the total nitrogen concentration meter 19. Next, the calculator 102 calculates the ratio between the nitrate nitrogen concentration and the total nitrogen concentration. The nitrate nitrogen concentration and the total nitrogen concentration in the treated water from the ditch 1 necessary for this calculation are the signal line 17a and the signal line 19a.
Nitrate nitrogen concentration meter 17 and total nitrogen concentration meter 1 via
Each is obtained from 9. The comparison calculator 122 determines whether the calculated value of the concentration ratio is within the management target range. The calculated value of the concentration ratio and the management target range necessary for this comparison are obtained from the calculator 102 and the setter 112 via the signal line 102a and the signal line 112a, respectively.

When the calculated value of the concentration ratio is larger than the upper limit value of the management target range, the intermittent operation schedule stored in the memory circuit 13 is selected to have the shortest operating time next to the currently operating schedule. select. On the contrary, when the calculated value is smaller than the lower limit value of the management target range, the one with the next longest operating time is selected. If the calculated value is within the management target range, the intermittent operation schedule is not changed. Others are the same as in the first embodiment.

As a result, if the ratio of the concentration of nitrate nitrogen to the concentration of total nitrogen is larger than the upper limit value of the management target range, the one having the shortest operating time next to the intermittent operation schedule currently in operation is selected and nitrification is performed. Suppress treatment and promote denitrification treatment. On the contrary, if it is smaller than the lower limit of the management target range, the schedule with the next longest operating time is selected to promote the nitrification treatment and suppress the denitrification treatment. That is, since the aeration device 2 is intermittently operated so that the ratio of the nitrate nitrogen concentration to the total nitrogen concentration is close to 1/2 even if the inflow load to the ditch 1 is changed, the third law is used. As described above, the nitrogen component in the sewage can always be removed well.

In the above reference example , the value obtained by dividing the nitrate nitrogen concentration by the total nitrogen concentration was used as an index and the aeration device 2 was used.
Although the example of changing the intermittent operation schedule is shown, the same effect can be obtained even if the intermittent operation schedule of the aeration apparatus 2 is changed using the reciprocal number, that is, the value obtained by dividing the total nitrogen concentration by the nitrate nitrogen concentration as an index.

The positional relationship between the nitrate nitrogen concentration meter 17 and the total nitrogen concentration meter 19 is not limited to that shown in FIG.
It may be installed at any point on the pipe b. Further, the same effect can be obtained even if it is installed at any point in the ditch 1, any point in the final settling basin, or any pipe for discharging the treated water from the final settling basin.

Furthermore, in the above-mentioned reference example , an example using the nitrate nitrogen concentration meter 17 and the total nitrogen concentration meter 19 was shown, but the nitrate nitrogen concentration and the total nitrogen concentration were calculated by manual analysis or estimated from plant data. Then, even if these are directly supplied to the arithmetic unit 102, the same effect can be obtained.

Reference Example 11 FIG. 19: is a block diagram which shows the oxidation ditch type water treatment apparatus which concerns on the reference example 11 using the 3rd law. In this reference example , the intermittent operation schedule of the aeration device is changed using the ratio of the ammonia nitrogen concentration and the total nitrogen concentration as an index.

In FIG. 19, 18 is an ammonia nitrogen concentration meter for measuring the ammonia nitrogen concentration in the treated water from the ditch 1, and 19 is the total nitrogen concentration in the treated water from the ditch 1, that is, the nitrate nitrogen concentration. And a total nitrogen concentration meter for measuring the sum of ammonia nitrogen concentrations, each of which is installed in a pipe b for sending the treated water from the ditch 1 to the final settling tank. Reference numeral 103 denotes a calculator for calculating the ratio of the concentration of ammonia nitrogen and the concentration of total nitrogen, which is connected to the total nitrogen concentration meter 19 via a signal line 19a and to the ammonia nitrogen concentration meter 18 via a signal line 18a. Reference numeral 113 is a setter for setting a management target range of the density ratio, and the management target range is set to a range of 0 to 0.9. Reference numeral 123 denotes a comparison calculator for determining whether or not the calculated value of the concentration ratio is within the management target range. The comparison calculator 123 is the calculator 103 and the signal line 103a, and the setter 113 and the signal line 113a. Of the memory circuit 13 and the signal line 123a. Others are the same as in FIG.

Next, the operation of the reference example 11 will be described. The ammonia nitrogen concentration in the treated water from the ditch 1 is measured by the ammonia nitrogen concentration meter 18, and the total nitrogen concentration is measured by the total nitrogen concentration meter 19. Next, the calculator 103 calculates the ratio between the ammonia nitrogen concentration and the total nitrogen concentration. The ammonia nitrogen concentration and total nitrogen concentration in the treated water from the ditch 1 necessary for this calculation are calculated by the signal line 1
8a and a signal line 19a to obtain from an ammonia nitrogen concentration meter 18 and a total nitrogen concentration meter 19, respectively. The comparison calculator 123 determines whether or not the calculated value of the concentration ratio is within the control target range. The calculated value of the concentration ratio and the management target range necessary for this comparison are the signal line 103.
It is obtained from the arithmetic unit 103 and the setting unit 113 via a and the signal line 113a, respectively.

When the calculated value of the concentration ratio is larger than the upper limit value of the management target range, the intermittent operation schedule stored in the storage circuit 13 is selected to have the shortest operating time next to the currently operating schedule. select. Conversely, when the calculated value is smaller than the lower limit value 0.1 of the management target range,
Select the one with the next longest operating time. If the calculated value is within the management target range, the intermittent operation schedule is not changed.
Others are the same as in the first embodiment.

As a result, if the ratio of the ammonia nitrogen concentration to the total nitrogen concentration is smaller than the lower limit value of the management target range, the one having the shortest operating time next to the intermittent operation schedule currently in operation is selected and nitrification is performed. Suppress treatment and promote denitrification treatment. On the contrary, if the upper limit value is less than 0.9, the schedule having the next longest operating time is selected to accelerate the nitrification treatment and suppress the denitrification treatment. That is, even if the inflow load to the ditch 1 changes, the aeration device 2 is intermittently operated so that the ratio of the ammonia nitrogen concentration to the total nitrogen concentration is close to 1/2, and therefore the third law is used. As described above, the nitrogen component in the sewage can always be removed well.

In the above reference example , the intermittent operation schedule is changed by using the value obtained by dividing the ammoniacal nitrogen concentration by the total nitrogen concentration as an index. Even if the intermittent operation schedule of the aeration device 2 is changed using the value divided by the nitrogen concentration as an index, the same effect can be obtained.

Further, the positional relationship between the ammonia nitrogen concentration meter 18 and the total nitrogen concentration meter 19 is not limited to that shown in FIG. 19, but may be installed at any point on the pipe b. Also, the same effect can be obtained by installing both of them at any point in the ditch 1, any point in the final settling basin, or a pipe for discharging the treated water from the final settling value.

Furthermore, in the above-mentioned reference example , an example in which the ammonia nitrogen concentration meter 18 and the total nitrogen concentration meter 19 are used is shown, but the ammonia nitrogen concentration and the total nitrogen concentration are obtained by measurement by manual analysis or estimation from plant data. Then, even if these are directly set in the arithmetic unit 103, the same effect is obtained.

In the above-mentioned Reference Examples 7 to 11 , the case where one aeration device was installed was described, but the number of aeration devices is not limited to this, and the case where two or more aeration devices are installed is also mentioned. Has the same effect.

Further, in each of the above embodiments and each reference example ,
Although the example in which the intermittent operation schedule of the aeration device is changed has been shown, even if the aeration strength of the aeration device is adjusted, the same effect as that of the above-mentioned reference example is obtained.

The nitrate nitrogen concentration used in each of the above reference examples may be considered including the concentration of nitrite nitrogen which is a product in the middle of the oxidation reaction from ammoniacal nitrogen to nitrate nitrogen.

Further, in each of the above embodiments and each reference example ,
Although the case of removing nitrogen is shown, it can be applied to the case of removing other pollutants such as organic matter or phosphorus.

Further, in each of the above embodiments and each reference example ,
Although the time continuous analog type is used , the same effect can be obtained even if the time discontinuous analog type (sample value type) or digital type is used.

Further, in each of the above embodiments and each reference example ,
Showed control circuitry, be implemented programmed in a computer it exhibits the similar effect.

Further, in each of the above embodiments and each reference example ,
Although the control circuit is configured as a closed loop, it may be configured as a driving support system that presents the control operation to the driving manager.

[0172]

As described above, according to claim 1 of the present invention, the aerobic region length integration is obtained by integrating the length of the region where the dissolved oxygen concentration in the oxidation ditch is higher than the reference value within a predetermined time range. Calculate the ratio of the value and the anaerobic region length integrated value obtained by integrating the length of the region where the dissolved oxygen concentration is lower than the reference value, and set the aeration device of the Ditch so that the ratio is within a predetermined control target range. Since it is controlled, the nitrogen component in the sewage can always be removed well and good water quality can be secured.

According to the second aspect of the present invention, the management target range of the ratio of the aerobic region length integrated value to the anaerobic region length integrated value is set to 0.
Since the range is set to 1 to 10, the aerobic region and the anaerobic region are appropriately formed in the ditch.

According to claim 3 of the present invention, the aerobic region length integrated value obtained by integrating the length of the region where the dissolved oxygen concentration in the oxidation ditch is higher than the reference value within a predetermined time range, and the dissolved oxygen. Since the difference was calculated with the anaerobic region length integrated value obtained by integrating the length of the region where the concentration is lower than the above reference value, and the ditch aeration device was controlled so that the above difference was within the predetermined control target range, Nitrogen components can always be removed well, and good water quality can be secured.

According to the fourth aspect of the present invention, the management target range of the difference between the aerobic region length integrated value and the anaerobic region length integrated value is set to -0.8 to 0.8 of the total length of the ditch per one hour of integration time. Since the double range is set, the aerobic region and the anaerobic region are appropriately formed in the ditch.

According to the fifth aspect of the present invention, since the dissolved oxygen concentration meter is moved along the dich flow direction, the length of the region where the dissolved oxygen concentration in the ditch is higher than the reference value,
Alternatively, the length of the region lower than the reference value can be easily measured.

According to claim 6 of the present invention, the dissolved oxygen concentration in the above-mentioned ditch is used as a reference value by using the dissolved oxygen concentration at any point in the oxidation ditch and plant data of the oxidation ditch such as aeration strength. higher area length of, or so to estimate the length of lower than the reference value region, configured easily ing.

According to claim 7 of the present invention, the dissolved oxygen concentration reference value in the oxidation ditch is 0 to 2 [mg /
Since it is set in the range of L], it is possible to properly judge the aerobic state and the anaerobic state in the ditch.

According to claim 8 of the present invention, since the management target range is corrected by using at least one of the water temperature, pH, and redox potential at any point in the oxidation ditch, a better water quality is obtained. Can be secured.

According to claim 9 of [0180] the present invention, since the calculation of the ratio or difference in the range of 1 to 48 hours, Ru can more efficiently control the aeration device.

According to a tenth aspect of the present invention, a measuring means for measuring the dissolved oxygen concentration in the ditch, a value obtained by integrating a length of a region where the dissolved oxygen concentration is higher than a reference value for a predetermined time,
A calculating means for calculating a ratio or a difference with a value obtained by integrating a length of a region where the dissolved oxygen concentration is lower than the reference value for a predetermined time, and a value calculated by the calculating means falls within a predetermined management target range. use via the control means for controlling the aeration device, so to constitute a control apparatus for oxidation ditch type water treatment apparatus, the water treatment device can always satisfactorily removing nitrogen components in sewage Ru obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a tank array model used in a computer simulation that has led to the discovery of the first to third laws according to the present invention.

FIG. 2 is a schematic diagram showing how the ratio of an aerobic region and an anaerobic region in a ditch changes with time.

FIG. 3 is a graph showing a relationship between an aerobic / anaerobic region length integration ratio and a nitrogen removal rate obtained by a simulation in the case of one aeration device.

FIG. 4 is a graph showing the difference in the dissolved oxygen concentration distribution when there is one aeration device and when there are two aeration devices.

FIG. 5 is a graph showing the relationship between the aerobic / anaerobic retention time ratio and the nitrogen removal rate obtained by a simulation when two aeration devices are used.

FIG. 6 is a graph showing the relationship between the ratio of nitrate nitrogen concentration and ammonia nitrogen concentration and the nitrogen removal rate obtained by a simulation in the case of one aeration device.

FIG. 7 is a graph showing the relationship between the ratio of nitrate nitrogen concentration and ammonia nitrogen concentration and the nitrogen removal rate obtained by a simulation when two aeration devices are used.

FIG. 8 is a conceptual diagram of an apparatus for realizing operation control that reflects the first law.

FIG. 9 is a conceptual diagram of an apparatus for realizing operation control that reflects a second law.

FIG. 10 is a configuration diagram showing an oxidation ditch type water treatment device according to a first embodiment of the present invention.

FIG. 11 is a configuration diagram showing an oxidation ditch type water treatment device according to a second embodiment of the present invention.

FIG. 12 is a configuration diagram showing an oxidation ditch type water treatment device according to a third embodiment of the present invention.

FIG. 13 is a configuration diagram showing an oxidation ditch type water treatment device according to a fourth embodiment of the present invention.

FIG. 14 is a configuration diagram showing an oxidation ditch type water treatment device according to a fifth embodiment of the present invention.

FIG. 15 is a configuration diagram showing an oxidation ditch type water treatment device according to Reference Example 4 of the present invention.

FIG. 16 is a configuration diagram showing an oxidation ditch type water treatment device according to Reference Example 5 of the present invention.

FIG. 17 is a configuration diagram showing an oxidation ditch type water treatment device according to Reference Example 7 of the present invention.

FIG. 18 is a configuration diagram showing an oxidation ditch type water treatment device according to Reference Example 10 of the present invention.

FIG. 19 is a configuration diagram showing an oxidation ditch type water treatment device according to Reference Example 11 of the present invention.

FIG. 20 is a configuration diagram showing a conventional oxidation ditch type water treatment device.

[Explanation of symbols]

1 ditch, 2,200 aeration device, 3,
301, 302, 303, 304, 305, 306 Dissolved oxygen concentration meter, 4, 14, 33, 140 controller, 5, 11, 110, 111, 112, 113 setter, 6 detector, 7, 9 integrator, 8 , 10, 60, 6
1, 80, 100, 101, 102, 103 arithmetic unit,
12, 120, 121, 122, 123 comparison calculator,
13 memory circuit, 15 thermometer, 16, 160 correction circuit, 17 nitrate nitrogen concentration meter, 18 ammonia nitrogen concentration meter, 19 total nitrogen concentration meter, 30, 34 computing means, 3
1,35 comparison calculation means, 32,36 setting means, 41
Drive device, 42 orbits, 62 integrated time meter, 600
Position sensor

Front page continuation (72) Inventor Koichi Tokimori 1-2-1, Wadasaki-cho, Hyogo-ku, Kobe Mitsubishi Electric Corporation Control Works (72) In-house Masahiro Shimaoka 1-1, Wadasaki-cho, Hyogo-ku, Kobe No. 2 Mitsubishi Electric Co., Ltd. (56) References JP-A-60-28891 (JP, A) JP-A-61-234991 (JP, A) JP-A-4-197497 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 3/12-3/34

Claims (10)

(57) [Claims] 1. An aerobic region length integrated value obtained by integrating the length of a region where the dissolved oxygen concentration is higher than a reference value in an oxidation ditch, and a region where the dissolved oxygen concentration is lower than the reference value, within a predetermined time range. A method of controlling an oxidation ditch type water treatment device, which calculates a ratio with an integrated value of the length of the anaerobic region and calculates the ratio so that the ratio is within a predetermined management target range. 2. The control of the oxidation ditch type water treatment device according to claim 1, wherein the management target range of the ratio of the integrated value of aerobic region length to the integrated value of anaerobic region is set to a range of 0.1 to 10. Method. 3. An aerobic region integrated value obtained by integrating lengths of regions in which the dissolved oxygen concentration is higher than a reference value in the oxidation ditch, and a region in which the dissolved oxygen concentration is lower than the reference value, within a predetermined time range. A method of controlling an oxidation ditch type water treatment device, which calculates a difference from an integrated value of the length of the anaerobic region and calculates the difference so that the difference is within a predetermined management target range. 4. The management target range of the difference between the aerobic region length integrated value and the anaerobic region length integrated value is set to a range of −0.8 to 0.8 times the total length of the ditch per one hour of integration time. 3. A method for controlling an oxidation ditch type water treatment device according to 3. 5. The length of the region where the dissolved oxygen concentration is higher than the reference value or the length of the region where the dissolved oxygen concentration is lower than the reference value is set by moving the dissolved oxygen concentration meter along the Ditch flow direction. The method for controlling an oxidation ditch type water treatment device according to any one of claims 1 to 4, wherein the measurement is performed. 6. The dissolved oxygen concentration at any point in the oxidation ditch or the plant data of the oxidation ditch is used to determine the length of the region where the dissolved oxygen concentration is higher than the standard value or lower than the standard value. The method of controlling an oxidation ditch type water treatment device according to claim 1, wherein the length of the region is estimated. 7. Control of oxidation ditch type water treatment device according to any one of claims 1 was set in a range of the reference value of the dissolved oxygen concentration in the oxidation ditch 0~2 [mg / L] 6 Method. 8. Any point within the oxidation ditch, water temperature, pH, and by using at least one oxidation-reduction potential, claims 1 to correct the management target range 7
5. A method for controlling an oxidation ditch type water treatment device according to any one of 1. 9. calculates the ratio or difference in the range of 1 to 48 hours, the control method of the oxidation ditch type water treatment device according to any one of claims 1 <br/> to 8 for controlling the aeration device . 10. A control device for an oxidation ditch water treatment device, wherein treated water flows into a ditch, activated sludge treatment is performed by an aeration device provided in the ditch, and nitrogen components in the treated water are removed. ,
Measuring means for measuring the dissolved oxygen concentration in the ditch, a value obtained by integrating the length of the region where the dissolved oxygen concentration is higher than a reference value for a predetermined time, and the length of the region where the dissolved oxygen concentration is lower than the reference value is predetermined. The present invention is characterized by further comprising: calculating means for calculating a ratio or difference with respect to the time integrated value; and control means for controlling the aeration device so that the value calculated by the calculating means falls within a predetermined management target range. Control device for oxidation ditch water treatment device.