JP6375257B2 - Water treatment equipment - Google Patents

Description

The present invention relates to a water treatment apparatus using activated sludge.

  In water treatment plants such as sewage treatment plants, various water treatment processes for removing environmental pollutants are introduced. For example, in the standard activated sludge method in which organic substances are to be removed, all the biological reaction tanks are aerobic tanks, and air is supplied by aeration. In the aerobic tank, aerobic heterotrophic bacteria oxidize organic matter and remove organic matter in sewage.

  On the other hand, in order to preserve the environment of closed water areas, the need for nitrogen removal in addition to organic matter removal is increasing. General nitrogen removal is realized by nitrification in an aerobic state and denitrification in an oxygen-free state. Nitrification is a reaction in which nitrifying bacteria use oxygen to oxidize ammonia nitrogen (NH4-N) in sewage to nitrate nitrogen (NO3-N) in an aerobic state. Denitrification is a reaction in which denitrifying bacteria use organic matter to reduce NO3-N to N2 gas in the absence of oxygen. Since N2 gas generated by denitrification is released into the atmosphere, nitrogen is removed from the liquid phase.

  In a general sewage treatment process, the reaction tank is fixed in a state such as an aerobic tank or an oxygen-free tank. Therefore, depending on the inflow load, the processing may become excessive or insufficient. Taking the nitrification endogenous denitrification method with an aerobic, anoxic, and aerobic tank as an example, if the inflow nitrogen load is low relative to the volume of the aerobic tank, the NH4-N concentration is targeted in the middle of the aerobic tank. The value may be met and subsequent aeration may be excessive. On the other hand, when the inflow nitrogen load is high, the nitrification ability in the aerobic tank becomes insufficient, and the NH4-N concentration may not satisfy the target water quality.

Therefore, a method of providing a switching tank capable of switching between an aerobic state and an anoxic state in accordance with the progress of nitrification has been proposed in order to suppress excessive aeration and improve nitrogen removal. For example, in patent document 1, the switching tank is installed downstream of the aerobic tank, the progress of nitrification in the aerobic tank is evaluated using an oxygen consumption rate meter, and the state of the switching tank is controlled. In Patent Document 2, a switching tank is installed upstream of the aerobic tank, and when the ammoniacal nitrogen concentration in the aerobic tank measured by measuring means such as an ammonia meter is equal to or less than a threshold value, the switching tank is in an oxygen-free state.

JP-A-8-117789 JP 2013-212490 A

  It is necessary to install measuring instruments that are not widely used in conventional sewage treatment plants, such as ammonia meters and oxygen consumption rate meters in the prior art, and purchase and purchase of measuring instruments, replacement costs for consumables, etc., and maintenance management of calibration, etc. Work occurs.

  In the prior art, the state of the switching tank is controlled based on the measured value of the aerobic tank, and the progress of nitrification in the switching tank is not taken into consideration. Therefore, the state in the switching tank is a single one, and when there are a plurality of switching tanks, the upstream switching tank in which NH4-N remains is in the aerobic state, the downstream side that has achieved the target ammonia concentration Such a switching tank is difficult to control such as anoxic state. In the configuration in which the switching tank is installed downstream of the aerobic tank as in Patent Literature 1, depending on the position of the aerobic tank in which the measuring device is installed, there may be a case where the target ammonia concentration is achieved upstream, and further air volume There seems to be room for reduction and nitrogen removal. Moreover, in patent document 1 and patent document 2, in addition to a blower, control of a stirrer and a draft tube aerator is required for the state control of a switching tank.

In order to achieve the above object, the present invention provides a water treatment apparatus for treating sewage with microorganisms,
A reaction tank including a plurality of switching tanks that can be switched between an aerobic state and an oxygen-free state, an air diffuser installed in at least the switch tank, a blower that supplies air to the air diffuser, and the reaction tank An inflow flow rate estimation unit for estimating the flow rate of the inflow water, an inflow ammonia concentration estimation unit for estimating the ammonia concentration of the inflow water to the reaction tank, a first air volume estimation unit for estimating the air volume to the switching tank,
An air volume control unit that controls the air volume to the switching tank; and a switching tank ammonia concentration estimation unit that estimates an ammonia concentration in the switching tank, wherein the switching tank ammonia concentration estimation unit includes: A first ammonia decrease amount calculating function for calculating an ammonia concentration decrease amount in the switching tank from an output value and an output value of the inflow flow rate estimating section, wherein the switching tank ammonia concentration estimating section includes the inflow ammonia concentration From the output value of the estimation unit and the ammonia concentration decrease amount in the switching tank calculated by the first ammonia decrease amount calculation function, the ammonia concentration in the switching tank is estimated, and among the plurality of switching tanks, In the switching tank in which the output value of the switching tank ammonia concentration estimation unit is equal to or lower than the target ammonia concentration with respect to the set target ammonia concentration, the air volume control unit Control is performed in an oxygen state, and the other switching tanks are controlled in an aerobic state.

  Further, in the water treatment apparatus according to the present invention, in the air volume control unit, the fine aeration air volume setting value in which the air volume to the switching tank is set in advance, or the air volume is reduced to zero, and the switching tank is in a pseudo anoxic state, or It is characterized by controlling to an anoxic state.

  Furthermore, the present invention is characterized in that, in the water treatment apparatus, the switching tank is installed on the most downstream side of the reaction tank.

  Furthermore, in the water treatment apparatus according to the present invention, the switching tank is installed on the downstream side of the aerobic tank, and includes a second air volume estimating unit that estimates an air volume to the aerobic tank, and the switching tank ammonia The concentration estimation unit has a second ammonia decrease amount calculation function for calculating an ammonia concentration decrease amount in the aerobic tank from the output value of the second air volume estimation unit and the output value of the inflow rate estimation unit, The switching tank ammonia concentration estimation unit uses the output value of the inflow ammonia concentration estimation unit, the ammonia concentration decrease amount in the aerobic tank calculated by the second ammonia decrease amount calculation function, and the first ammonia decrease amount calculation function. The ammonia concentration in the switching tank is estimated from the calculated ammonia concentration decrease amount in the switching tank.

Furthermore, the present invention provides a water treatment apparatus,
The inflow flow rate estimation unit estimates the flow rate of inflow water to the reaction tank using at least one of the date, day of the week, and precipitation, or to the reaction tank using inflow rate measurement means. The flow rate of inflow water is measured.

  Further, in the water treatment apparatus according to the present invention, the inflow ammonia concentration estimation unit uses the at least one item among date and time, day of the week, precipitation, and flow rate of inflow water to the reaction tank, It is characterized by estimating the ammonia concentration of the inflow water to the tank.

Furthermore, the present invention provides a water treatment apparatus,
An organic substance concentration measuring means for measuring the organic substance concentration of the sewage is installed upstream of the reaction tank, and the inflow ammonia concentration estimation unit is configured to include a date, a day of the week, precipitation, and a flow rate of inflow water to the reaction tank. And the ammonia concentration of the inflow water to the reaction tank is estimated using at least one item of the output value of the organic substance concentration measuring means.

According to the present invention, in a sewage treatment apparatus having an aerobic tank, a NH4-N concentration in each reaction tank is estimated and a switching tank state is controlled without using a new measuring instrument. Thereby, the expense concerning a new measuring device and maintenance work can be reduced. Moreover, since it is not restrict | limited to the installation position of a measuring device and the state of a switching tank can be controlled, air volume reduction and nitrogen removal improvement can be made compatible. Furthermore, since it is possible to control the state of the switching tank only by air volume control, it is not necessary to introduce a stirrer or the like.

It is a block diagram which shows the structure of the water treatment apparatus S which concerns on Example 1. FIG. Control flow diagram according to embodiment 1 Relationship between air volume on simulator and decrease in NH4-N concentration NH4-N concentration in sewage and each reaction tank for each state of switching tank 2-a, 2-b

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram illustrating a configuration of a water treatment device S according to the first embodiment. This water treatment device S removes organic matter and nitrogen using activated sludge.

(Configuration of water treatment equipment)
As shown in FIG. 1, the water treatment device S includes an aerobic tank 1, a switching tank 2 (2 a and 2 b), and a final sedimentation tank 3 as main components. The function of these components will be described below.
(Aerobic tank)
The sewage 100 and the return sludge 102 flow into the aerobic tank 1, and nitrification is performed to oxidize NH4-N to NO3-N by nitrifying bacteria in the activated sludge. In addition, organic matter oxidation by aerobic heterotrophic bacteria is performed.
(Switching tank)
The switching tank 2 (2-a and 2-b) is a tank that can switch the state in the tank between an aerobic state and an oxygen-free state. When the switching tank 2 is in an aerobic state, the remaining NH4-N is nitrified to NO3-N, and organic matter oxidation by aerobic heterotrophic bacteria is also performed. When the switching tank 2 is in an oxygen-free state, the remaining NO3-N is denitrified into N2 gas by denitrifying bacteria in the activated sludge.
(Final sedimentation basin)
The final settling basin 3 is a facility that separates and separates the supernatant liquid and activated sludge. The supernatant liquid that has settled and separated is discharged out of the system as treated water 101. Moreover, the activated sludge separated and separated is returned to the aerobic tank 1 as the return sludge 102 and used again for a series of biological treatments.

Hereinafter, the water treatment apparatus S will be described in more detail.

As shown in FIG. 1, sewage 100 and return sludge 102 from the final sedimentation tank 3 flow into the aerobic tank 1. The aerobic tank 1 is provided with an aerobic tank aeration unit 4. Switching tanks 2-a and 2-b are installed on the downstream side of the aerobic tank 1, and effluent water from the aerobic tank 1 flows into the switching tank 2-a, and enters the switching tank 2-b. Flows out from the switching tank 2-a. Moreover, switching tank aeration parts 5-a and 5-b are installed in the switching tanks 2-a and 2-b, respectively. The blower 6 is installed in the aerobic tank air diffuser 4, the switching tank air diffuser 5-a, and the switch tank air diffuser 5-b, and air is supplied thereto. Air flow valves 7-a and 7-b are connected to the switching tank air diffusers 5-a and 5-b, respectively. A final sedimentation tank 3 is installed on the downstream side of the switching tank 2-b, and communicates with the aerobic tank 1 through the flow path 800 and the return pump 8.

  A flow meter 9 and a return sludge flow meter 10 which are inflow flow rate measuring means are installed in the upstream of the aerobic tank 1 and the flow path 800, respectively. The flow rate of the sewage 100 is measured by the flow meter 9. Similarly, the flow rate of the return sludge 102 is measured by the return sludge flow meter 10. The flow meter 9 and the return sludge flow meter 10 are connected to the inflow flow rate estimation unit 11. The inflow flow rate estimation unit 11 calculates the flow rate of the inflow water to the aerobic tank 1 by adding the measurement value of the flow meter 9 and the measurement value of the return sludge flow meter 10.

  An inflow ammonia concentration estimation unit 12 equipped with a database that records the relationship between the date and time, the day of the week, precipitation, the flow rate of inflow water to the aerobic tank 1 and the NH4-N concentration of inflow water to the aerobic tank 1 Install. The inflow ammonia concentration estimation unit 12 considers the date, day of the week, and precipitation amount based on the flow rate of the inflow water to the aerobic tank 1 calculated by the inflow rate estimation unit 11, and NH4 of the inflow water to the aerobic tank 1. -Estimate N concentration.

  An air flow meter 13 is installed from the blower 6 to the branch pipe to each reaction tank, and the air flow supplied from the blower 6 is measured. The air flow meter 12 is connected to an air flow estimation unit 14 that is a first air flow estimation unit and a second air flow estimation unit. The air volume estimation unit 14 estimates the air volume to the aerobic tank 1 and the switching tanks 2-a and 2-b from the air volume of the blower 6 measured by the anemometer 13.

  The inflow flow rate estimation unit 11, the inflow ammonia concentration estimation unit 12, and the air volume estimation unit 14 are connected to a switching tank ammonia concentration estimation unit 15. The switching tank ammonia concentration estimation unit 15 is equipped with a first ammonia decrease amount calculation function and a second ammonia concentration decrease amount calculation function, and the flow rate of inflow water to the aerobic tank 1 estimated by the inflow rate estimation unit 11 From the air volume to the aerobic tank 1 and the switching tanks 2-a and 2-b estimated by the air volume estimation unit 14, the amount of decrease in the ammonia concentration in the aerobic tank 1 and the switching tanks 2-a and 2-b is calculated. Calculate. Further, the switching tank ammonia concentration estimation unit 15 calculates the ammonia concentration decrease amount in each reaction tank and the NH 4 -N concentration of the inflow water to the aerobic tank 1 estimated by the inflow ammonia concentration estimation unit 12. The NH4-N concentration in the air tank 1 and the switching tanks 2-a and 2-b is estimated.

The switching tank ammonia concentration estimation unit 15 is connected to the air volume control unit 16. The air volume control unit 16 is connected to the air volume valves 7-a and 7-b, and is based on the NH 4 -N concentration of the switching tanks 2-a and 2-b estimated by the switching tank ammonia concentration estimation unit 15. The opening degree of 7-a, 7-b is controlled. For example, if the NH4-N concentration in the aerobic tank 1 is less than or equal to the target ammonia concentration, the opening degree of the air volume valves 7-a and 7-b is reduced to the minimum air volume that can maintain stirring in the tank, and the switching tank 2-a and 2-b are controlled to a pseudo anoxic state (pseudo anoxic state) by fine aeration stirring.

FIG. 2 shows an air flow control flow to the switching tank according to the first embodiment. Hereinafter, the control flow of the air volume to the switching tank in the present embodiment will be described in detail.

First, in step 101 (hereinafter referred to as S101), a target ammonia concentration (C _{NH — 0} ) is set.

Next, in S102, the flow rate (Q _w (t)) of the sewage 100 is measured by the flow meter 9, and the flow rate (Q _r (t)) of the return sludge 102 is measured by the return sludge flow meter 10. In S103, the inflow rate estimation unit 11 calculates the inflow rate (Q _in (Q _in ()) into the aerobic tank 1 as the sum of the sewage 100 flow rate (Q _w (t)) and the return sludge 102 flow rate (Q _r (t)). t)) is calculated.

In S <b> 104, the NH 4 -N concentration (C _{N_in} (t)) of the inflow water to the aerobic tank 1 is estimated by the inflow ammonia concentration estimation unit 12. In general sewage treatment plants, there are fluctuation patterns in the flow rate and quality of influent sewage, and the fluctuation pattern varies depending on the day of the week and the weather conditions such as precipitation. In S104, the date and time, the day of the week, the amount of precipitation, the flow rate of the inflow water to the aerobic tank 1, and the database recording the relationship between the NH4-N concentration of the inflow water to the aerobic tank 1 are used. The NH4-N concentration (C _{N_in} (t)) of the inflow water to the aerobic tank 1 from the day of the week, the precipitation, and the flow rate of the inflow water to the aerobic tank 1 calculated by the inflow amount estimation unit 11 Is estimated.

  In S105, based on the air volume of the blower 6 measured by the air volume meter 13, the air volume estimating unit 14 estimates the air volume to the aerobic tank 1, the switching tanks 2-a and 2-b from the air volume distribution ratio to each tank. To do. The air volume distribution ratio to each tank is a function of the opening degree of the air volume valves 7-a and 7-b. For example, the air volume distribution ratio to each tank is calculated by the calculation formula (1).

Here, Q _B [m ³ / min]: the air volume of the blower 6, Q _{B (reaction tank)} [m ³ / min]: the air volume of any one of the aerobic tank 1 and the switching tanks 2-a and 2-b, VO _{reaction tank} [-]: Set the valve opening of either the aerobic tank 1 or the switching tanks 2-a and 2-b. Further, the valve opening degree (VO _{aerobic tank} ) of the aerobic tank 1 is set to 1.0. However, when an air flow valve is installed in the piping from the blower 6 to the aerobic tank 1, the valve opening degree is set. Follow.

In S106, the switching tank ammonia concentration estimation unit 15 uses the first ammonia decrease amount calculation function and the second ammonia decrease amount calculation function, so that the NH4-N concentrations in the aerobic tank 1, the switching tanks 2-a and 2-b are used. Is estimated. In the first ammonia decrease amount calculation function and the second ammonia decrease amount calculation function, the NH4-N concentration decrease amount is calculated from the supply air volume in each reaction tank.
FIG. 3 shows the result of examining the relationship between the supply air volume in the aerobic tank and the decrease amount of the NH 4 -N concentration on a simulator simulating an actual sewage treatment plant. It can be seen that the amount of decrease in NH4-N concentration can be estimated from the supplied air volume. Since the supplied air volume is an integrated value of the air volume supplied while the sewage 100 stays in each reaction tank, the air volume supplied to each reaction tank and the flow rate (Q _in (t )). The decrease amount of NH4-N concentration in the aerobic tank 1 and the switching tanks 2-a and 2-b calculated by the ammonia decrease amount calculation function is subtracted from the NH4-N concentration of the inflow water to the aerobic tank 1. By this, NH4-N density | concentration of the aerobic tank 1, switching tank 2-a, 2-b is estimated.

  In S107, the estimated value of the NH4-N concentration in the switching tanks 2-a and 2-b is compared with the target ammonia concentration. The conceptual diagram of NH4-N density | concentration in each reaction tank for every state of the aerobic tank 1 and the switching tanks 2-a and 2-b is shown in FIG. When the nitrification sufficiently proceeds in the aerobic tank 1 and the estimated value of the NH4-N concentration in the aerobic tank 1 is equal to or lower than the target ammonia concentration, in S108, the air volume control unit 16 causes the air volume valve 7-a, The opening degree of 7-b is reduced, and the switching tanks 2-a and 2-b are set in a pseudo anoxic state (pseudo anoxic state) by fine aeration and stirring (graph of FIG. 4A). On the other hand, if the estimated value of the NH4-N concentration in the aerobic tank 1 is higher than the target ammonia concentration, the switching tank 2-a maintains the aerobic state. Next, when the nitrification sufficiently proceeds in the switching tank 2-a in an aerobic state and the estimated value of the NH4-N concentration in the switching tank 2-a becomes equal to or lower than the target ammonia concentration, the switching tank 2-b Control to a pseudo anoxic state (graph in FIG. 4). On the other hand, if the nitrification in the switching tank 2-a in the aerobic state is insufficient and the estimated value of the NH4-N concentration in the switching tank 2-a is higher than the target ammonia concentration, the aerobic state is maintained (FIG. 4 o graph).

  Thus, without introducing a new measuring instrument such as an NH4 meter, the NH4-N concentration in each reaction tank is estimated and the state of the switching tank is controlled, so that it is possible to suppress excessive aeration and improve nitrogen removal. . Moreover, even when there are a plurality of switching tanks, the position and number of control to the pseudo-anoxic state can be determined according to the estimated value of the NH4-N concentration in each switching tank.

  In the present embodiment, the flow rate of the sewage 100 is measured by the flow meter 9, but at least the date, the day of the week, and the precipitation amount are recorded using a database that records the relationship between the date, day of the week, and the precipitation amount and the flow rate of the sewage 100. The flow rate of the sewage 100 may be estimated from one item. In this embodiment, the flow rate of the return sludge 102 is measured by the return sludge flow meter 10, but it is not always necessary to install the return sludge flow meter 10. For example, the return sludge flow rate is controlled to a constant flow rate ratio with respect to the sewage 100. If it is, it may be calculated from the flow rate of the sewage 100 and the flow rate ratio to the sewage 100.

In this embodiment, the inflow ammonia concentration estimation unit 12 determines the relationship between the date and time, the day of the week, the amount of precipitation, the flow rate of the inflow water to the aerobic tank 1, and the NH4-N concentration of the inflow water to the aerobic tank 1. Although the recorded database was mounted, the database which recorded the relationship between the date and time, a day of the week, precipitation, the flow volume of the sewage 100, and NH4-N of the sewage 100 may be mounted. In this case, the NH4-N concentration of the inflow water to the aerobic tank 1 is estimated according to the following procedure. First, the date, day of the week, precipitation, and flowmeter 9 were used to measure the date, day of the week, precipitation, the flow rate of sewage 100, and the relationship between NH4-N in sewage 100 and the flow meter 9. From the flow rate of the sewage 100, the NH4-N concentration (C N — _w (t)) of the sewage 100 is estimated. Next, assuming that the target water quality related to NH4-N is achieved in the water treatment apparatus S, the NH4-N concentration (C N — _r (t)) of the return sludge 102 is set to the target ammonia concentration (C NH — ₀ ). Since the inflow water to the aerobic tank 1 is a mixed water of the sewage 100 and the return sludge 102, the NH4-N concentration (C _{N_in} (t)) of the inflow water to the aerobic tank 1 based on the formula (2). ).

Here, _{CN_in} (t) [mg / L]: NH4-N concentration of the inflow water to the aerobic tank 1 at time t, _{CN_w} (t) [mg / L]: NH4- of the sewage 100 at time t N concentration, C N — _r (t) [mg / L]: NH 4 —N concentration in the return sludge 102 at time t, Q _w (t) [m ³ / min]: Flow rate of sewage 100 at time t, Q _r (t ) [M ³ / min]: The flow rate of the return sludge 102 at time t. Note that C _{N — r} (t) may be set to the target ammonia concentration (C _{NH — 0} ).

  In the present embodiment, the NH4-N concentration of the inflow water to the aerobic tank 1 is recorded in the database of the inflow ammonia concentration estimation unit 12, but it is not necessarily the NH4-N concentration, and the total nitrogen concentration, etc. Any index that can estimate the NH4-N concentration may be used. In addition, any index other than the nitrogen component may be used as long as it can estimate the NH 4 -N concentration. For example, in a sewage treatment plant having a variation pattern in the ratio of the organic matter concentration to the nitrogen concentration in the sewage 100, An organic matter concentration meter that is an inflowing organic matter concentration measuring means may be installed, and the NH4-N concentration of the inflowing water to the aerobic tank 1 may be estimated from the organic matter concentration of the sewage 100 measured by the organic matter concentration meter.

  In the present embodiment, the air volume estimating unit 14 estimates the air volume to each reaction tank from the air volume of the blower 6 measured by the air volume meter 13, but the air volume meter 13 is installed in a pipe connecting the blower 6 to each reaction tank. Then, the air volume to each reaction tank may be measured.

  In this embodiment, in the first ammonia decrease amount calculation function and the second ammonia decrease amount calculation function, the NH4-N concentration decreases as a function of the air volume to each reaction tank and the flow rate of the inflow water to the aerobic tank 1. Although the amount is calculated, in addition to the air volume and the inflow rate, terms related to water quality such as water temperature, activated sludge concentration, and organic matter concentration may be added. The water temperature, activated sludge concentration, and organic matter concentration may be measured by a measuring instrument or may be referred to a database. Further, a dissolved oxygen (DO) meter or the like may be installed in an aerobic tank or the like, and the function relating to the air volume and the decrease amount of the NH4-N concentration may be corrected from the relationship between the air volume and DO.

  In this embodiment, when the switching tank 2 is brought into an oxygen-free state, it is set in a pseudo oxygen-free state by slightly aerated stirring. However, instead of stirring by slightly aerated, a stirrer is installed and stirring by a stirrer is performed. good. In addition, when a membrane-type air diffuser that does not cause backflow of activated sludge even when aeration is stopped is used as the switching tank aeration unit 5, aeration may be stopped for a short time.

  In this example, the control of the state of the switching tank 2-a and the switching tank 2-b was performed based on the estimated values of the NH4-N concentrations in the aerobic tank 1 and the switching tank 2-a, respectively. You may have a time delay. For example, if the time when the estimated value of the NH4-N concentration in the switching tank 2-a becomes equal to or less than the target ammonia concentration is t, Δt expressed as a function of the flow rate of the inflow water to the aerobic tank 1 is added. At time t + Δt, the state of the switching tank 2-b may be controlled to a pseudo anoxic state. In addition, at the time when the estimated value of the NH4-N concentration in the switching tank 2 (2-a, 2-b) becomes equal to or lower than the target ammonia concentration, the state of the switching tank 2 (2-a, 2-b) is simulated. You may control to an oxygen state.

  In the present embodiment, the configuration is the aerobic tank 1 and the switching tank 2, but the configuration of only the switching tank 2 may be used. Moreover, this control is applicable also in the process which has an anaerobic tank and an anaerobic tank, such as an anaerobic aerobic activated sludge method and an anaerobic aerobic anaerobic method.

  In this embodiment, the switching tank 2 is installed on the most downstream side of the water treatment device S. In a normal oxygen-free tank stirred with a stirrer, denitrification bubbles are generated, and the sedimentation property of activated sludge in the final sedimentation basin is lowered. Therefore, it is necessary to install an aerobic tank for removing denitrification bubbles after the anaerobic tank. On the other hand, since the switching tank 2 is agitated by slight aeration even in the pseudo-anoxic state, denitrification bubbles are removed, and a subsequent aerobic tank becomes unnecessary. Therefore, when setting the target ammonia concentration, it is not necessary to consider the amount of NH4-N reduction in the subsequent aerobic tank, and the control reliability is improved. In addition, this control is applicable also when an aerobic tank is installed in the most downstream of the water treatment apparatus S.

This control is characterized in that a new measuring instrument such as an NH4 meter is not used, but can also be applied when an NH4 meter is introduced. For example, an ammonia meter may be installed upstream of the aerobic tank 1 and the NH4-N concentration of the inflow water to the aerobic tank 1 may be measured.

S ... Water treatment equipment
100 ... Sewage
101 ... treated water
102 ... Return sludge
800… Transfer flow path for return sludge
1 ... Aerobic tank
2 ... Switch tank
3 ... Final sedimentation basin
4… Aerobic tank diffuser
5… Switching tank diffuser
6… Blower
7 ... Air flow valve
8 ... Return pump
9… Flow meter
10 ... Return sludge flow meter
11… Inflow flow rate estimation unit
12… Inflow ammonia concentration estimation part
13 ... Air flow meter
14 ... Air volume estimation unit
15 ... Switching tank ammonia concentration estimation section
16 ... Air volume control unit

Claims (7)

In a water treatment device that treats sewage with microorganisms,
A reaction tank including a plurality of switching tanks that can be switched between an aerobic state and an oxygen-free state;
At least a diffuser installed in the switching tank;
A blower for supplying air to the air diffuser;
An inflow flow rate estimation unit for estimating the flow rate of inflow water to the reaction vessel;
An inflow ammonia concentration estimation unit for estimating the ammonia concentration of the inflow water to the reaction tank;
A first air volume estimating unit for estimating an air volume to the switching tank;
An air volume control unit for controlling the air volume to the switching tank;
A switching tank ammonia concentration estimation unit for estimating the ammonia concentration in the switching tank;
A first ammonia reduction amount calculation function in which the switching tank ammonia concentration estimation unit calculates an ammonia concentration reduction amount in the switching tank from the output value of the first air volume estimation unit and the output value of the inflow flow rate estimation unit. With
The switching tank ammonia concentration estimation unit calculates the ammonia concentration in the switching tank from the output value of the inflow ammonia concentration estimation unit and the ammonia concentration decrease amount in the switching tank calculated by the first ammonia decrease amount calculation function. Estimate
Among the plurality of switching tanks, in the switching tank in which the output value of the switching tank ammonia concentration estimation unit is equal to or lower than the target ammonia concentration with respect to a preset target ammonia concentration, the air volume control unit makes an oxygen-free state. The water treatment apparatus is characterized in that the other switching tank is controlled to be in an aerobic state.
The water treatment device of claim 1,
The air volume control unit is characterized in that the air volume to the switching tank is set to a fine aeration air volume setting value set in advance, or the air volume is reduced to zero, and the switching tank is controlled to a pseudo anoxic state or an oxygen-free state. Water treatment equipment.
In the water treatment apparatus of Claim 1 or Claim 2,
The water treatment apparatus, wherein the switching tank is installed on the most downstream side of the reaction tank.
The water treatment device according to any one of claims 1 to 3, wherein the switching tank is installed on the downstream side of the aerobic tank,
A second air volume estimating unit for estimating an air volume to the aerobic tank;
A second ammonia reduction amount calculation function in which the switching tank ammonia concentration estimation unit calculates an ammonia concentration reduction amount in the aerobic tank from the output value of the second air volume estimation unit and the output value of the inflow rate estimation unit. With
The switching tank ammonia concentration estimation unit outputs the output value of the inflow ammonia concentration estimation unit, the ammonia concentration decrease amount in the aerobic tank calculated by the second ammonia decrease amount calculation function, and the first ammonia decrease amount calculation function The ammonia concentration in the said switching tank is estimated from the ammonia concentration reduction amount in the switching tank calculated by (1).
In one water treatment apparatus in any one of Claims 1-4,
The inflow flow rate estimation unit estimates the flow rate of inflow water to the reaction tank using at least one of the date, day of the week, and precipitation, or to the reaction tank using inflow rate measurement means. A water treatment device that measures the flow rate of inflow water.
In one water treatment apparatus in any one of Claims 1-5,
The inflow ammonia concentration estimation unit estimates the ammonia concentration of the inflow water to the reaction tank using at least one of the date, day of the week, precipitation, and the flow rate of the inflow water to the reaction tank. The water treatment apparatus characterized by performing.
In one water treatment apparatus in any one of Claims 1-6,
An organic substance concentration measuring means for measuring the organic substance concentration of the sewage is installed upstream of the reaction tank, and the inflow ammonia concentration estimation unit is configured to include a date, a day of the week, precipitation, and a flow rate of inflow water to the reaction tank. And the ammonia concentration of the inflow water to the said reaction tank is estimated using at least 1 item among the output values of the said organic substance density | concentration measurement means, The water treatment apparatus characterized by the above-mentioned.

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