JP2002320989A - Biological water treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological water treatment equipment capable of efficiently controlling contaminant concentration after discharging treatment as a target value by setting a proper amount of air supply to mix water to be treated with the air so as to be cleaned even when a quantity of contaminant fluctuates in the water to be treated. SOLUTION: Air diffusers 41-44 are provided in the direction of flowing down the water to be treated in a biological reaction layer 1, and air supply devices 51-54 for supplying air are connected to each air diffuser 41-44, respectively. Furthermore, controllers 91-94 are connected to air supply device 51-54, respectively, and respective air supply amounts supplied from the air diffusers 41-44 connected to the controllers, respectively, are calculated by using an operation expression on the basis of values measured with a BOD concentration meter 2, a flowmeter 2 and a BOD concentration meter 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological water treatment apparatus for purifying municipal sewage and organic wastewater by a biological reaction.

[0002]

2. Description of the Related Art As described in "Water treatment engineering (edited by Tetsuo Ide, Technical Hall)", there is an activated sludge method as a general method for treating municipal sewage and organic wastewater.
The activated sludge method is a group of microorganisms that have a purification function (activated sludge).
Is stored in a biological reactor, and aerated while mixing and contacting the wastewater with the sewage to oxidize and decompose pollutants in the sewage. In order to sufficiently purify the contaminants, it is necessary to supply an appropriate amount of air to the biological reaction tank. FIG. 4 is a cross-sectional view of a conventional biological water treatment apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 11-141566. In the figure, 1 is a biological reaction tank storing activated sludge, and a pipe a
The sewage as treated water (pre-treatment water) flowing through is purified by a biological reaction, and the treated water (treated water) after the purification treatment is discharged to a pipe b. 2 measures the flow rate of sewage by a flow meter attached to the pipe a. Reference numeral 3 denotes a sedimentation tank for sedimenting a mixed liquid of the activated sludge and the water to be treated discharged from the biological reaction tank 1 via the pipe b, and the supernatant water after the sedimentation treatment is discharged via the pipe c. Is done. The activated sludge separated by the sedimentation treatment is returned to the biological reaction tank 1 via the pipe d, but the surplus is discharged to the outside via the pipe e. Reference numeral 4 denotes an air diffuser provided in the biological reaction tank 1 for supplying air sent from the air supply device 5 through the pipe 5a into the biological reaction tank 1. Reference numeral 6 denotes a flow meter for measuring an air supply amount. Reference numeral 7 denotes a BOD concentration meter for measuring the BOD concentration of sewage (index of biological oxygen demand, amount of organic pollutants), which is attached to the pipe a. Reference numeral 8 denotes a biological reaction tank 1 based on the BOD concentration measured by the BOD concentration meter 7 and the flow rate measured by the flow meter 2.
Calculation device for calculating the amount of air supply to the
The OD concentration is via signal line 7a and the flow rate is via signal line 2a.
Input via a. Reference numeral 9 denotes a controller for inputting the set value of the air supply amount calculated by the arithmetic unit 8 via the signal line 8a and controlling the air supply amount to the air supply unit 5. The controller 9 is connected to the air supply device 5 via a signal line 9a, and to the flow meter 6 via a signal line 9b.

The operation of such a conventional biological water treatment apparatus will be described. The sewage is introduced into the biological reaction tank 1 via the pipe a. The biological reaction tank 1 is supplied with air from an air supply device 5 via a pipe 5 a and a diffuser 4. By mixing and stirring this air, sewage and activated sludge, pollutants in the sewage are biologically oxidatively decomposed. If the amount of incoming sewage is large, it is necessary to increase the air supply for biological oxidative degradation. Conversely, when the amount of sewage flowing in is small, the air supply amount may be small. In the sedimentation tank 3, after the activated sludge is separated from the mixed solution, the supernatant water is discharged via the pipe c. Part of the separated activated sludge is returned to the biological reaction tank 1 via the pipe d. Other surplus sludge is discharged out of the system via the pipe e. The arithmetic unit 8 inputs the flow rate of the sewage through the signal line 2a, and inputs the BOD concentration of the sewage through the signal line 7a. Further, the BO in the preset treated water is
The D density target value is held. Then, the set value G [Nm ³ / h] of the air supply amount is calculated according to the following equation. G = a (S−S ₀ ) Q + bQ + c S; BOD concentration in sewage [mg / l] S ₀ ; BOD concentration target value [mg / l] Q; sewage flow rate [m ³ / h] a, b, c The coefficient controller 9 inputs the calculated set value G via the signal line 8a, and controls the amount of air supplied from the air supply device 5 according to the value. Then, the air whose supply amount is controlled is supplied from the air diffuser 4 into the biological reaction tank 1.
As described above, the air supply amount is set according to the amount of sewage contaminants before purification obtained by the product of the sewage flow rate and the BOD concentration, and a predetermined amount of air is supplied into the biological reaction tank 1.

[0004]

In such a conventional biological water treatment apparatus, the amount of pollutants (BOD) in the sewage is reduced.
The air supply to the biological reaction tank was controlled according to the product of the concentration and the flow rate. However, while urban sewage, whose main source is ordinary households, varies significantly in flow rate and properties depending on the time of day, the residence time in biological reactors is
It is often designed to be 6 to 8 hours in consideration of the time required for activated sludge microorganisms to decompose pollutants (sewerage facility planning and design guidelines). Therefore, even during the residence in the biological reaction tank, the flow rate of the flowing sewage and the BOD concentration vary greatly. However, in the conventional biological water treatment apparatus, the amount of air supplied to the entire biological reaction tank is controlled only by the amount of contaminants at the entrance of the biological reaction tank, and no consideration is given to the contaminants at the exit of the biological reaction tank. Therefore, the amount of air supplied into the biological reaction tank may be inappropriate. That is, BO at the outlet of the reaction tank
Even if the D concentration is high, if the amount of contaminants at the inlet of the reaction tank is small, the amount of air supply will decrease. As a result, as a result, B
There was a problem that the OD concentration or the amount of pollutants could not be controlled to the target value.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to set an appropriate air supply amount to the water to be treated, carry out a biological reaction treatment, and carry out the treatment. It is an object of the present invention to obtain a biological water treatment apparatus capable of controlling the concentration of pollutants in sewage water to a target value.

[0006]

In the biological water treatment apparatus according to the present invention, means for measuring the concentration of contaminants S _IN of the pre-treatment water before the purification treatment, and the flow rate Q of the pre-treatment water
Means for measuring _IN , means for measuring the concentration of contaminants S _OUT of the treated water, air supply means for diffusing air into the water to be treated in the reaction tank, and contaminants for the treated water before treatment Dispersion from the air supply means according to the amount of contaminants of the pre-treatment water obtained by the product of the concentration S _IN and the flow rate Q _IN of the pre-treatment water, and the measured contaminant concentration S _{OUT of the} post-treatment water. It is provided with a means for adjusting the air supply amount to be considered.

A plurality of (n) air supply means are provided along the direction in which the water to be treated flows down, and the means for adjusting the air supply amount includes a target value S ₀ of the concentration of contaminants in the treated water and each of the air supply means. A first coefficient k _i1 , a second coefficient
Coefficient _{k i2} and constants _k and _i holds, the following equation air supply amount _{G i} to air diffusion from the air supply means _{G i = k i1 · S IN} · Q IN + k i2 · (S OUT of the -
S ₀ ) + k _i (i = 1,..., N).

Further, the first coefficient k _i1 defined for each air supply means is larger as the air supply means close to the inlet portion of the reaction vessel, a smaller value as the air supply means close to the discharge unit (k ₁₁ > K ₂₁ >...> k _n1 ), the second coefficient k
_i2, the more air supply means close to the inlet of the reactor reduced, and larger value air supply means close to the discharge unit _{(k 12 <k 22 <···} <k n2) is intended.

[0009] Contamination of the pre-treatment water before the purification treatment
Concentration S_INFor measuring the flow rate of the pre-treatment water_INTo
Means of measurement, pollutant concentration S of treated water_OUTMeasure
Means are provided along the direction in which the water to be treated flows down.
Multiple (n) air supplies for diffusing air into the treated water
Supply means and the measured contaminant concentration S of the treated water
_OUTAnd the measured contaminant concentration S of the pre-treatment water._IN
And the flow rate Q of the pre-treatment water _INAnd the pre-treatment water obtained by multiplying
And the amount of pollutants from the air supply means on the upstream side
Air from each of the above air supply means according to the air supply amount
Means for adjusting the amount of supplied air.

The means for adjusting the amount of air supply comprises a target value S ₀ of the concentration of contaminants in the treated water and a first coefficient k _i1 and a second coefficient k _{i2 which} are predetermined for each air supply means. , And a constant k _i , and the air supply amount G _i diffused from each air supply means is expressed by the following equation: G _i = G _i1 + G _i2 + k _i where i = 1 G ₁₁ = k ₁₁ · S _IN G _{12 = k 12 · (S OUT} -S 0) i = 2, ···, by _{G i1 = k i1 · G (} i1) 1 G i2 = k i2 · G (i1) 2 when n It is to be calculated.

When i = 2,..., N, the first coefficient k _i1 defined for each air supply means is set to a value smaller than 1, and the second coefficient k _i2 is larger than 1. Value.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram showing a biological water treatment apparatus according to an embodiment of the present invention. In the drawings, the same reference numerals as those in other drawings indicate the same or corresponding parts. In FIG. 1, reference numeral 1 denotes a biological reaction tank storing activated sludge, which purifies water before treatment as water to be treated flowing through a pipe a by a biological reaction, and supplies treated water after the purification treatment to a pipe b. Discharge. Reference numeral 2 denotes a flow meter attached to the pipe a for measuring the flow rate of the pre-treatment water flowing into the biological reaction tank 1. Reference numeral 3 denotes a sedimentation tank for sedimenting activated sludge contained in the post-treatment water discharged from the biological reaction tank 1 via the pipe b, and the supernatant water after the sedimentation treatment is discharged via the pipe c. The activated sludge separated by the sedimentation treatment is supplied to the biological reaction tank 1 via a pipe d.
The excess is discharged to the outside through the pipe e. Reference numerals 41 to 44 denote diffusers provided in the biological reaction tank 1 in the direction in which the water to be treated flows down.
The air sent from 1 to 54 via the pipes 51 a to 54 a is supplied into the biological reaction tank 1. Reference numeral 7 denotes a BOD concentration meter for measuring the BOD concentration (indicator of the amount of biological oxygen required and the amount of organic pollutants) of the pre-treatment water, and is attached to the pipe a. Reference numeral 10 denotes a BOD concentration meter for measuring the BOD concentration of the treated water discharged from the biological reaction tank 1, and is attached to the pipe b. Reference numerals 91 to 94 denote controllers for controlling the amount of air supplied to the air supply devices 51 to 54 via signal lines 91a to 94a, respectively.
B of the treated water input via the concentration and signal line 10a
A set value of the air supply amount is calculated based on the OD concentration and the flow rate input via the signal line 2a. Note that the positional relationship between the flow meter 2 and the BOD concentration meter 7 is not limited to this figure, and either one may be upstream.

[0013] In the biological water treatment apparatus configured as described above, as before, the pre-treatment water flowing through the pipe a is mixed and stirred with the activated sludge and the air in the biological reaction tank 1, as in the prior art. Purification treatment by biologically oxidatively decomposing the pollutants. The flow rate of the pre-treatment water flowing into the biological reaction tank 1 is measured by the flow meter 2 and transmitted to the controllers 91 to 94 via the signal line 2a. At the same time, the BOD concentration of the pre-treatment water is measured by the BOD concentration meter 7, and the signal line 7a
Are transmitted to the controllers 91 to 94 via the. Similarly, the BOD concentration of the treated water discharged from the biological reaction tank 2 is measured by the BOD concentration meter 10 and transmitted to the controllers 91 to 94 via the signal line 10a. Controller 9
1 to 94, based on the measured values, the air diffusers 41 to 94
The set value of the air supply amount supplied from 44 is obtained by calculation.

Each controller holds a first coefficient, a second coefficient, and a constant which are predetermined in the air supply means connected to each controller.
The sum of the following (a), (b), and (c) is calculated based on a and each measurement value transmitted via the signal line 10a. (A) An amount obtained by multiplying the product of the BOD concentration of the pre-treatment water measured by the BOD concentration meter 7 and the flow rate of the pre-treatment water measured by the flow meter 2 by a first coefficient. (B) BOD concentration meter 10 BOD of treated water measured at
An amount obtained by multiplying the difference between the concentration and a predetermined target value of the BOD concentration by a second coefficient. (C) Constant The amount calculated in this way is transmitted to the air supply means connected to each controller. As a result, that amount of air is supplied from each of the aeration devices from the biological reaction tank. Note that the first coefficient, the second coefficient, and the constant are optimal air supply amounts for the BOD concentration of the treated water discharged from the biological reaction tank 1 to be closer to a predetermined BOD concentration target value. , Which are set in advance so as to be obtained in the above calculation, and different values are set depending on the position or the number of the air diffusers.

For example, in the controller 91, the set value G ₁ [Nm ³ / h] of the air supply amount supplied from the air diffuser 41.
Is calculated by the following equation (1). _{G 1 = k 11 · S IN} · Q IN + k 12 · (S OUT -S 0) + k 13 ... (1) S IN; processing BOD concentration measuring value before water [mg / _{l] Q IN;} flow rate measurement value [ m ³ / h] S _OUT ; measured value of BOD concentration of treated water [mg / l] S ₀ ; target value of BOD concentration of treated water [mg / l] k ₁₁ , k ₁₂ , k ₁₃ ; constant Then, the controllers 92 to 94 calculate the set values G _{2 to} G ₄ [Nm ³ / h] of the air supply amount according to the following equations (2) to (4), respectively. G ₂ = k ₂₁ · S _IN · Q _IN + k ₂₂ · (S _OUT -S ₀ ) + k ₂₃ (2) k ₂₁ , k ₂₂ , k ₂₃ ; first coefficient, second coefficient, constant G ₃ = _{k 31 · S iN · Q iN} + k 32 · (S OUT -S 0) + k 33 ... (3) k 31, k 32, k 33; first coefficient, the second coefficient, the constant G ₄ = _{k 41} · S _IN · Q _IN + k ₄₂ · (S _OUT −S ₀ ) + k ₄₃ (4) k ₄₁ , k ₄₂ , k ₄₃ ; first coefficient, second coefficient, constant

Here, in the above equations (1) to (4), the first coefficient and the second coefficient which are predetermined for each air diffuser are, as described above, the BOD concentration of the treated water. This is a value that is set in advance so that an optimal air supply amount for approaching the predetermined target value of the BOD concentration can be obtained in the above calculation.
₁₁ , k ₂₁ , k ₃₁ , and k ₄₁ are k ₁₁ ≧ k ₂₁ ≧ k
₃₁ ≧ such relationship holds for _{k 41,} while the second coefficient _{k 12, k 22, k 32} , k 42 _{is, k 12 ≦ k 2 2 ≦} k
Relationship ₃₂ ≦ _{k 42} sets the value so established. As a result, as the amount of air supplied from the air diffuser closer to the upstream (inlet) of the biological reaction tank 1, the amount of contaminants (BOD) in the pre-treatment water becomes larger than the difference between the BOD concentration of the treated water and the target value. (Product of the concentration and the flow rate), and conversely, the air supply amount supplied from the air diffuser closer to the downstream (outlet) of the biological reaction tank 1 is mainly after the treatment, rather than the contaminant amount of the pre-treatment water. It is determined according to the difference between the BOD concentration of water and its target value. The above manner set value G ₁ of the air supply amount calculated by ~G ₄ each signal line 91a~
The air is transmitted to the air supply devices 51 to 54 via the 94a.
In each of the air supply devices 51 to 54, the pipes 51a to 51a are respectively provided.
A set amount of air is supplied into the biological reaction tank 1 via the air passage 54a and the air diffusers 41 to 44. In the above description, four air diffusers are used. However, for example, even when only one air diffuser 41 is provided, the first coefficient k ₁₁ , the second coefficient k ₁₂ , and the constant k ₁₃ are used as the air diffusers. air but separately predetermined optimal value when the one air supply amount G ₁ is calculated by the above equation (1), not only the contamination quantity of the pretreatment water, BOD concentration of the processed water is also taken into consideration Amount can be supplied. Furthermore, even if there are five or more air diffusers, it goes without saying that the optimum amount of air supplied from each air diffuser can be easily calculated.

As described above, not only the amount of the contaminants of the pre-treatment water flowing into the biological reaction tank 1 but also the difference between the concentration of the contaminants of the post-treatment water currently discharged from the biological reaction tank 1 and its target value. Since the amount of air to be supplied into the biological reaction tank 1 is set while taking into account, the concentration of contaminants in the treated water discharged after the treatment can be made closer to the target value, and the water quality can be controlled more precisely. Further, in the calculation for obtaining the air supply amount, by assigning a magnitude relationship to the coefficients determined according to the positions in the biological reaction tank 1 of the air diffusers 41 to 44 connected to the air supply means 51 to 54, respectively. From the diffuser near the inflow portion of the biological reaction tank 1 depending on the amount of contaminants of the pre-treatment water flowing in, and from the diffuser near the discharge portion of the biological reaction tank 1 mainly the pollutants of the treated water. Since air is supplied according to the difference between the concentration and the target value, an appropriate air supply can be realized at each point of the biological reaction tank 1 even if the amount of contaminants flowing in varies.
The pollutant concentration of the discharged post-treatment water can be made closer to the target value. Further, efficient water quality control can be performed with an adequate amount of air supply.

Embodiment 2 FIG. FIG. 2 is a configuration diagram showing a biological water treatment apparatus according to Embodiment 2 of the present invention.
In FIG. 2, 1-3, 41-44, 51a-54
Reference numerals a, 7, and 10 denote the same or corresponding parts as those of the first embodiment shown in FIG. Reference numeral 50 denotes an air supply device which sends air to the valves 71 to 74 via the pipe 50a. Valves 71 to
Numeral 74 is a valve for controlling the amount of air supplied from the air diffusers 41 to 44 connected thereto. 90
Is a controller that calculates a set value of the amount of air supplied from each of the air diffusers 41 to 44 based on each measured value transmitted through the signal lines 2a, 7a, and 10a, and transfers the set value to the signal line 7
The signal is transmitted to valves 71 to 74 via 1a to 74a.

In the second embodiment thus configured, the flow rate of the pre-treatment water flowing into the biological reaction tank 2 measured by the flow meter 2 and the BOD concentration of the pre-treatment water measured by the BOD concentration meter 7 , And the BOD concentration of the treated water discharged from the biological reaction tank 1 measured by the BOD concentration meter 10 are transmitted to the controller 90 via the signal line 2a, the signal line 7a, and the signal line 10a, respectively. Controller 90
In formulas (1) to (3) described in the first embodiment,
Using (4), set values G ₁ [Nm ³ / h], G ₂ [Nm ³ / h], G _{3 of the} air supply amount supplied from each of the air diffusers 41 to 44
[Nm ³ / h] and G ₄ [Nm ³ / h] are calculated. Again, as in the first embodiment, the coefficient _{k 11} of predetermined corresponding to each air diffuser in the above equation (1) ~ (4), k 21, k 31,
k _41, the relationship between _{k 11 ≧ k 21 ≧ k 3} 1 ≧ k 41 sets the value so established. Also, k ₁₂ , k ₂₂ , k
_{32, k 42,} the relationship between _{k 12 ≦ k 22 ≦ k 32} ≦ k 42 sets the value so established.

The set values G _{1 to} G ₄ of the air supply amount calculated by the controller 90 are signal lines 71 a to 74 a, respectively.
To valves 71-74. The valves 71 to 74 are used for controlling the amount of air transmitted from the air diffusers 41 to 44 to the biological reaction tank 1.
As it supplied within, adjusting the opening in accordance with the respective set value G ₁ ~G _4. Thus, from the air supply device 50, the pipe 50a, the valves 71 to 74, and the pipes 51a to 51
A predetermined amount of air can be sent through 4a and the air diffusers 41 to 44. As described above, the calculation of the amount of air supplied from each diffuser is performed collectively by one controller, and the adjustment of the amount of air sent to each diffuser is performed using the valve. Even if the number of devices increases, the number of controllers and air supply devices does not increase, and it can be realized with a simple configuration.

Embodiment 3 FIG. 3 is a configuration diagram illustrating a biological water treatment apparatus according to Embodiment 3 of the present invention.
3 are the same as or correspond to those of the first embodiment shown in FIG.
The BOD concentration of the pre-treatment water measured by the OD densitometer 7, the flow rate of the pre-treatment water measured by the flow meter 2, and the BOD concentration of the post-treatment water measured by the BOD densitometer 10 are represented by signal lines 7a and 7a, respectively. Controller 91 via 2a and 10a
Only conveyed to. Further, the controller 91 calculates a set value of the amount of air supplied from the air diffuser 41, and transmits the calculation formula to the controller 92 one downstream via the signal line 91b. Similarly, from the controller 92 to the controller 93, the controller 93 is connected via a signal line 92b.
To the controller 94 via the signal line 93b.

In the third embodiment configured as described above, first, in the controller 91, the signal lines 7a,
BO before treatment water transmitted through 2a, and 10a
Based on the D concentration and its flow rate, the BOD concentration of the treated water, and the third coefficient k ₁₁ , fourth coefficient k ₁₂ , and constant k ₁ predetermined for the air supply device 51, Set value G ₁ [Nm ³
/ h] is calculated according to the following equation (5). G ₁ = G ₁₁ + G ₁₂ + k ₁ (5) G ₁₁ = k ₁₁ · S _IN · Q _{ING 12} = k ₁₂ · (S _OUT −S ₀ ) where S _IN ; BOD concentration measurement value of pre-treatment water [ mg / l] Q _IN ; flow rate measurement value [m ³ / h] S _OUT ; BOD concentration measurement value of treated water [mg / l] S ₀ ; target value of BOD concentration of treated water [mg / l] k ₁₁ , k ₁₂ , k ₁ ; third coefficient, fourth coefficient, constant Note that the third coefficient and the fourth coefficient are BOD concentrations in which the BOD concentration of the treated water is predetermined as described above. Is a value that is set in advance so that an optimal air supply amount for approaching the target value can be obtained in the above calculation.

The controller 91 calculates G _{11 in the} above equation (5).
It passes the value of the value and _{G 12} to the controller 92 via a signal line 91b. The controller 92 holds a predetermined third coefficient k ₂₁ , fourth coefficient k ₂₂ , and constant k ₂ for the air supply device 52, and sets the air supply amount to be supplied from the air diffuser 42. value _{G 2} [Nm ³
/ h] is calculated according to the following equation (6). G ₂ = G ₂₁ + G ₂₂ + k ₂ (6) G ₂₁ = k ₂₁ · G ₁₁ G ₂₂ = k ₂₂ · G ₁₂ where 0 <k ₂₁ <1, 1 <k ₂₂ . Similarly, the controller 92, the value of _{G 21} of the above equation (6) and G
The value of ₂₂ is transmitted to the controller 93 via the signal line 92b. In the controller 93, the air supply device 53
Holds a _third coefficient k ₃₁ , a fourth coefficient k ₃₂ , and a constant k ₃ , and sets a set value G ₃ [Nm ³ / h] of the air supply amount supplied from the air diffuser 43. Is given by the following equation (7).
Calculated according to G ₃ = G ₃₁ + G ₃₂ + k ₃ (7) G ₃₁ = k ₃₁ · G ₂₁ G ₃₂ = k ₃₂ · G ₂₂ provided that 0 <k ₃₁ <1,1 <k ₃₂ . Furthermore, the controller 93, the value of _{G 31} of the above equation (7) and G
The value of ₃₂ is transmitted to the controller 94 via the signal line 93b. In the controller 94, the air supply device 54
Holds a third coefficient k ₄₁ , a fourth coefficient k ₄₂ , and a constant k ₄ , and sets a set value G ₄ [Nm ³ / h] of the amount of air supplied from the air diffuser 44. Is given by the following equation (8).
Calculated according to G ₄ = G ₄₁ + G ₄₂ + k ₄ (8) G ₄₁ = k ₄₁ · G ₃₁ G ₄₂ = k ₄₂ · G ₃₂ where 0 <k ₄₁ <1, 1 <k ₄₂ .

As described above, the set value of the amount of air supplied from the air diffuser provided in the direction in which the water to be treated flows in the biological reaction tank 1 is changed to the air supplied from the air diffuser on one upstream side. Since the calculation is performed in consideration of the amount, a more precise air supply amount can be set. The third coefficient weighted to the upstream BOD concentration is set to a value smaller than 1, and the fourth coefficient weighted to the difference between the concentration of the treated water to be discharged and the target value is set to a value larger than 1. Thereby, the air diffuser near the inflow portion of the biological reaction tank 1 mainly depends on the amount of contaminants of the inflowing pre-treatment water, and the air diffuser near the discharge portion of the biological reaction tank 1 mainly emits post-treatment water. A predetermined amount of air is supplied according to the difference between the concentration of pollutants and its target value, so even if the amount of contaminants in the incoming pre-treatment water fluctuates, appropriate air supply is achieved at each point in the biological reaction tank. It is possible to precisely control the concentration of pollutants discharged after treatment.

In the first to third embodiments, the case where the BOD concentration is used as an index as the pollutant concentration of the water to be treated has been described. However, the same effect can be obtained when the nitrogen concentration or the phosphorus concentration is targeted. Play. In addition, although an example is shown in which the BOD concentration of the inflowing pre-treatment water and the BOD concentration of the post-treatment water are measured by separate BOD concentration meters, it is also possible to measure with a single sensor. In that case, the measurement periods of both may be shifted. Further, these BOD densitometers do not necessarily need to be attached to pipes, and may be installed in any location as long as they can sample and measure water before or after treatment. Also,
In order to measure the BOD concentration of the water after treatment, an example was shown in which the water was attached to the pipe b for discharging the water after treatment from the biological reaction tank or sampling was performed from the pipe b. The same effect can be obtained by attaching to the pipe c for sampling or sampling from the pipe c. Furthermore, the case where four diffusers are provided has been described. However, this is merely an example, and the number of diffusers is arbitrary. Coefficients and constants to be held in advance corresponding to each diffuser are The optimum value is set in accordance with the number of air diffusers. Note that the device configuration is the same even if the number of air diffusers changes.

[0026]

The present invention is configured as described above, and has the following effects.

Contaminant concentration S of pre-treatment water before purification treatment
Means for measuring _IN , means for measuring the flow rate Q _{IN of the} pre-treatment water, means for measuring the contaminant concentration S _OUT of the post-treatment water discharged, and for diffusing air into the water to be treated in the reaction tank. Air supply means, and the amount of contaminants in the pre-treatment water obtained by the product of the measured contaminant concentration S _IN of the pre-treatment water and the flow rate Q _IN of the pre-treatment water and the measured post-treatment water Since there is provided a means for adjusting the amount of air diffused from the air supply means in accordance with the concentration S _OUT of the contaminants, the concentration of contaminants in the post-treatment water discharged can be precisely controlled. Also,
The quality of the treated water can be controlled efficiently with an adequate amount of air supply.

A plurality (n) of air supply means are provided along the direction in which the water to be treated flows down, and the means for adjusting the air supply amount includes a target value S ₀ of the concentration of contaminants in the treated water and each of the air supply means. A first coefficient k _i1 , a second coefficient
Coefficient _{k i2} and constants _k and _i holds, the following equation air supply amount _{G i} to air diffusion from the air supply means _{G i = k i1 · S IN} · Q IN + k i2 · (S OUT of the -
Since _{S 0) + k i (i} = 1, ··, calculated by n), according to the position in the reaction vessel of the air supply means, to set the appropriate air supply amount, can be performed better water quality control efficiency.

The first coefficient k _i1 determined for each air supply means is larger as the air supply means is closer to the inflow portion of the reaction tank, and smaller as the air supply means is closer to the discharge portion (k _11). > K ₂₁ >...> k _n1 ), the second coefficient k
_i2, the more air supply means close to the inlet of the reactor reduced, since the larger value air supply means close to the discharge unit _{(k 12 <k 22 <···} <k n2), the inflow of the reaction vessel From the air supply means close to the reactor mainly depends on the amount of contaminants in the pre-treatment water, and from the air supply means close to the outlet of the reaction tank mainly depends on the difference between the concentration of the contaminants in the post-treatment water and its target value. Respectively, so that even if the amount of pollutants in the incoming treated water fluctuates, an appropriate amount of air can be supplied from each air supply means of the reaction tank, and the concentration of Can be brought closer to the target value.

Means for measuring the contaminant concentration S _IN of the pre-treatment water before the purification treatment; means for measuring the flow rate Q _{IN of the} pre-treatment water;
_OUT measuring means, a plurality of (n) air supply means provided along the direction in which the water to be treated flows down to diffuse air into the water to be treated, and the measured water after treatment The concentration of contaminants S _OUT , the amount of contaminants of the pre-treatment water obtained by the product of the measured contaminant concentration S _IN of the pre-treatment water and the flow rate Q _IN of the pre-treatment water; In accordance with the air supply amount diffused from the supply unit, the air supply amount is diffused from each of the air supply units, and the air supply amount is adjusted. Air volume can be supplied.

The means for adjusting the amount of air supply comprises a target value S ₀ of the concentration of contaminants in the treated water and a first coefficient k _i1 and a second coefficient k _i2 predetermined for each air supply means. , And a constant k _i , and the air supply amount G _i diffused from each air supply means is expressed by the following equation: G _i = G _i1 + G _i2 + k _i where i = 1 G ₁₁ = k ₁₁ · S _IN G _{12 = k 12 · (S OUT} -S 0) i = 2, ···, by _{G i1 = k i1 · G (} i1) 1 G i2 = k i2 · G (i1) 2 when n Since the calculation is performed, an appropriate air supply amount can be set according to the position of each air supply unit in the biological reaction tank, and efficient water quality control can be performed.

When i = 2,..., N, the first coefficient k _i1 defined for each air supply means is set to a value smaller than 1, and the second coefficient k _i2 is larger than 1. Value.
Depending on the amount of contaminants of the pre-treatment water flowing in from the air supply means near the inlet of the reaction tank, and the concentration of the contaminants in the water after treatment mainly from the air supply means near the discharge part of the reaction tank and the target value Air is supplied according to the above, so that even if the amount of pollutants in the inflowing treated water fluctuates, an appropriate amount of air can be supplied from each air supply means, and the discharged treated water is discharged. Can be brought closer to the target value.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a biological water treatment apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a biological water treatment apparatus according to Embodiment 2 of the present invention.

FIG. 3 is a configuration diagram showing a biological water treatment apparatus according to Embodiment 3 of the present invention.

FIG. 4 is a configuration diagram showing a conventional biological water treatment apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Biological reaction tank, 2 Flow meter, 41-44 Air diffuser as air supply means, 51-54 Air supply apparatus as air supply means, 7 BOD concentration meter as contaminant concentration measurement means of pre-treatment water, 91 -94 Controller as means for adjusting air supply amount, 10 BOD concentration meter as means for measuring contaminant concentration of treated water.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hisao Tanaka 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Mitsubishi Electric Corporation 4D028 CA09 CB03 CB05 CC01 CC02 CC05

Claims (6)

[Claims] 1. A biological water treatment apparatus for purifying water to be treated flowing into a reaction tank by mixing it with activated sludge and air, and discharging the treated water after the purification treatment from the reaction tank. A means for measuring the contaminant concentration S _IN of the water to be treated (hereinafter referred to as pre-treatment water) before the purification treatment, a means for measuring a flow rate Q _IN of the treatment water, (Hereinafter, referred to as post-treatment water) means for measuring the contaminant concentration S _OUT , air supply means for diffusing air into the water to be treated in the reaction tank, and the measured contamination of the pre-treatment water. From the air supply means in accordance with the contaminant amount of the pre-treatment water obtained by multiplying the contaminant concentration S _IN and the flow rate Q _IN of the pre-treatment water and the measured contaminant concentration S _{OUT of the} post-treatment water. It is characterized by having a means for adjusting the air supply amount to diffuse. To biological water treatment equipment. Wherein provided a plurality of air supply means along a direction in which water to be treated flows down (n pieces), means for adjusting the air supply quantity, the target value S ₀ of the pollutant concentration of the processed water each first coefficient k _i1 predetermined for each air supply _means, the second to hold the coefficient k _i2, and constant k _i, the following equation the air supply amount G _i to air diffusion from the air supply means G _i = _{k i1 · S IN · Q IN} + k i2 · (S OUT -
_{S 0) + k i (i} = 1, ··, n) biological water treatment apparatus according to claim 1, wherein the calculating the. 3. The first coefficient k _i1 determined for each air supply means is larger as the air supply means is closer to the inflow portion of the reaction tank, and smaller as the air supply means is closer to the discharge portion (k _11). > K ₂₁ >...> k _n1 ), the second coefficient k _i2
Is smaller as the air supply means is closer to the inflow portion of the reaction tank, and larger as the air supply means is closer to the discharge portion (k
_{12 <k 22 <··· <k} n2) that biological water treatment apparatus according to claim 2, wherein. 4. A biological water treatment apparatus for purifying water to be treated flowing into a reaction tank by mixing it with activated sludge and air, and discharging the water to be treated after the purification treatment from the reaction tank. Means for measuring the pollutant concentration S _IN of the pre-treatment water before the purification treatment, means for measuring the flow rate Q _{IN of the} pre-treatment water,
A means for measuring the concentration of contaminants S _OUT of the discharged treated water, a plurality (n) of air provided along the direction in which the treated water flows, for diffusing air into the treated water; Supply means, and the measured contaminant concentration S of the treated water
_OUT and the measured contaminant concentration S _{IN of the} pre-treatment water.
And the flow rate Q _IN of the pre-treatment water and the amount of contaminants of the pre-treatment water, and the amount of air supply diffused from the air supply means on one upstream side. A biological water treatment apparatus, comprising: means for adjusting a supply amount of air diffused from a biological water treatment apparatus. 5. The means for adjusting the amount of air supply comprises water after treatment.
Target value S of pollutant concentration₀And each air supply means in advance
The first coefficient k determined_i1, The second coefficient k _i2,and
Constant k_iAnd the air diffused from each air supply means
Supply G_iIs given by the following equation G_i= G_i1+ G_i2+ K_i However, when i = 1, G₁₁= K₁₁・ S_IN G₁₂= K₁₂・ (S_OUT-S₀) When i = 2, ..., n, G_i1= K_i1・ G_{(I-1) 1} G_i2= K_i2・ G_{(I-1) 2} The organism according to claim 4, wherein the creature is calculated by:
Water treatment equipment. 6. When i = 2,..., N, the first coefficient k _i1 determined for each air supply means is a value smaller than 1.
The biological water treatment apparatus according to claim 5, wherein the second coefficient _ki2 has a value larger than 1.