Water treatment device and water treatment method

Abstract

To provide a water treatment apparatus capable of optimizing an intermittent aeration operation, by accurately evaluating a treatment state of water to be treated by directly grasping a nitrogen behavior in water to be treated in water treatment of intermittent aeration treating a nitrogen component in water to be treated, and a water treatment method.SOLUTION: To solve the above problem, there are provided: a water treatment apparatus provided with a control part which calculates the nitrification rate in one predetermined cycle of processing time and, based on the nitration rate, adjusts the processing time in the next one cycle and an amount of air supplied by the aeration in the treatment time of the next one cycle; and a water treatment method using the apparatus. According to the present invention, the treatment state of the water to be treated can be accurately evaluated by directly grasping the behavior of nitrogen in the water to be treated. Further, the nitrogen control in the water to be treated can be finely performed, thereby optimizing the intermittent aeration operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water treatment device and a water treatment method, and more particularly to a water treatment device and a water treatment method for nitrification / denitrification of nitrogen components in water to be treated. [Background technology]

[0002] Various treatment methods for wastewater treatment are known, and a treatment method is selected according to the components to be removed from the wastewater. For example, nitrification / denitrification is one of the treatment methods when the wastewater contains nitrogen components as the components to be removed.

[0003] An example of such a nitrification / denitrification process is a biological nitrification / denitrification process that uses activated sludge to reduce nitrogen components in the treated water to nitrogen gas. This biological nitrification / denitrification process using activated sludge is known as a process that includes a nitrification step in which ammonia nitrogen is nitrified to nitrate nitrogen and nitrite nitrogen by nitrifying bacteria under aerobic conditions, and a denitrification step in which nitrate nitrogen and nitrite nitrogen are reduced to nitrogen gas by denitrifying bacteria under anaerobic conditions.

[0004] One type of biological nitrification / denitrification process is known as intermittent aeration, in which the water being treated, which contains nitrogen components, is aerated and then stopped, forming one cycle of a nitrification process under aerobic conditions and a denitrification process under anaerobic conditions.

[0005] For example, Patent Document 1 describes a method of nitrification / denitrification treatment of water to be treated that contains nitrogen components, using intermittent aeration treatment. Patent Document 1 also describes that the pH in a reaction tank where intermittent aeration treatment is performed is measured over time, and when the difference between the maximum and minimum pH values ​​in one cycle of the intermittent aeration treatment falls below a predetermined value, the amount of water to be treated that is supplied to the reaction tank is reduced. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-36558 A Summary of the Invention [Problem to be solved by the invention]

[0007] It is known that the water treatment device used for the intermittent aeration treatment as described in Patent Document 1 can perform treatment within one tank and can easily be made compact. For this reason, water treatment using the intermittent aeration treatment is widely used to treat water containing nitrogen components.

[0008] In addition, water treatment using intermittent aeration involves two stages of treatment, a nitrification process under aerobic conditions and a denitrification process under anaerobic conditions, performed by aeration and then stopping aeration in one tank, and so operational management of the treatment processes is important. For this reason, it is necessary to grasp the treatment status related to the progress of the nitrification and denitrification processes and to control them to maintain stable operation.

[0009] In Patent Document 1, pH is used as an index to grasp the treatment state in the intermittent aeration treatment. However, when pH is used as an index, the treatment state of the water to be treated is indirectly evaluated, so it cannot be said that the operation control in the intermittent aeration treatment is sufficiently optimized. Therefore, there is a demand for optimizing the operation control in the intermittent aeration treatment by using an index that can more accurately evaluate the treatment state of the water to be treated.

[0010] An object of the present invention is to provide a water treatment apparatus and a water treatment method that can directly grasp the nitrogen behavior in the water to be treated by intermittent aeration to remove nitrogen components in the water to be treated, accurately evaluate the treatment state of the water to be treated, and optimize intermittent aeration operation. [Means for solving the problem]

[0011] As a result of extensive research into the above-mentioned problems, the inventors have discovered that in a water treatment device that performs intermittent aeration treatment, by providing a control unit that calculates the nitrification rate during a predetermined treatment time for one cycle and adjusts the treatment time for the next cycle and the amount of air supplied by aeration during the treatment time for the next cycle, it is possible to directly grasp the behavior of nitrogen in the water to be treated, accurately evaluate the treatment state of the water to be treated, and optimize intermittent aeration operation, thereby completing the present invention. That is, the present invention provides the following water treatment device and water treatment method.

[0012] In order to solve the above problems, the water treatment device of the present invention is a water treatment device that removes nitrogen components in the water to be treated by intermittent aeration operation, and is characterized in that it is equipped with a control unit that calculates the nitrification rate during a predetermined treatment time of one cycle, and adjusts the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the nitrification rate obtained.

[0013] According to the water treatment device of the present invention, a control unit is provided and the nitrification rate for each cycle is calculated, thereby directly grasping the behavior of nitrogen in the water to be treated and accurately evaluating the treatment state of the water to be treated. Furthermore, by adjusting the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the calculation results, the nitrogen in the water to be treated can be finely controlled, and the intermittent aeration operation can be optimized.

[0014] In one embodiment of the water treatment device of the present invention, the control unit determines the denitrification treatment amount from the value of the ammoniacal nitrogen concentration and / or the nitrate nitrogen concentration at the end of one cycle of treatment time. According to this feature, the control unit uses the values ​​of the ammoniacal nitrogen concentration and / or nitrate nitrogen concentration at the end of one treatment cycle to determine the denitrification treatment amount, which is the treatment amount in the denitrification process, so that the treatment state of the treated water can be accurately evaluated and the nitrogen in the treated water can be precisely controlled, thereby optimizing the intermittent aeration operation.

[0015] In addition, in one embodiment of the water treatment device of the present invention, the control unit is characterized in that it adjusts the amount of water to be treated based on the maximum or minimum value of the ammoniacal nitrogen concentration and / or the nitrate nitrogen concentration during treatment. According to this feature, the control unit uses the maximum or minimum value of the ammoniacal nitrogen concentration and / or nitrate nitrogen concentration during treatment to directly grasp the nitrogen behavior in the water to be treated and accurately evaluate the treatment state of the water to be treated. By adjusting the input amount of water to be treated based on this value, it is possible to precisely control the nitrogen in the water to be treated and optimize the intermittent aeration operation.

[0016] In one embodiment of the water treatment device of the present invention, the control unit adjusts the amount of hydrogen donor added in order to control the amount of denitrification treatment. According to this feature, in order to control the amount of denitrification treatment in the control unit, not only the operations related to stirring and aeration but also the adjustment of the amount of hydrogen donor added can be performed, thereby enabling precise control of nitrogen in the treated water and optimizing the intermittent aeration operation.

[0017] The water treatment method of the present invention for solving the above problems is a water treatment method that removes nitrogen components in the water to be treated by intermittent aeration operation, and is characterized in that it includes a control step in which an operation involving aeration and stirring is defined as one cycle, a nitrification rate is calculated for a predetermined treatment time of one cycle, and the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle are adjusted based on the nitrification rate thus calculated.

[0018] According to the water treatment method of the present invention, the nitrification rate for each cycle is calculated as a control step, which allows the behavior of nitrogen in the water to be treated to be directly understood and the treatment state of the water to be treated to be accurately evaluated. In addition, by adjusting the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the calculation results, the nitrogen in the water to be treated can be finely controlled, and the intermittent aeration operation can be optimized. Effect of the Invention

[0019] According to the present invention, in water treatment in which nitrogen components in the water to be treated are intermittently aerated, a water treatment apparatus and a water treatment method can be provided which can directly grasp the nitrogen behavior in the water to be treated, accurately evaluate the treatment state of the water to be treated, and optimize the intermittent aeration operation. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic explanatory diagram showing a water treatment device according to an embodiment of the present invention. [Diagram 2] 4 is a graph showing an example of a measurement result obtained by a measurement unit in the water treatment device according to the embodiment of the present invention. [Diagram 3] FIG. 4 is a flow chart showing an example of control by a control unit in the water treatment device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a flow chart showing another example of control by the control unit in the water treatment device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The water treatment device and the water treatment method of the present invention are used for treating water containing nitrogen components. In particular, the water treatment device and the water treatment method of the present invention are used for an intermittent aeration process, which is one type of biological nitrification / denitrification process, in which the water containing nitrogen components is treated by performing each of the steps of aeration and agitation once, forming one cycle.

[0022] The water to be treated W in the present invention is not particularly limited as long as it contains nitrogen components to be treated. Specific examples of such water to be treated include wastewater such as industrial wastewater and domestic wastewater. In particular, examples of the water to be treated W that contains ammonia nitrogen or nitrate nitrogen as nitrogen components include sewage and human waste.

[0023] Hereinafter, embodiments of the water treatment device and the water treatment method according to the present invention will be described in detail with reference to the drawings. The water treatment method according to the present invention is replaced with the following description of the structure and operation of the water treatment device. Furthermore, the structure of the water treatment device described in the embodiments is merely an example for explaining the water treatment device according to the present invention, and is not limited thereto.

[0024] [Implementation] (Water treatment equipment) FIG. 1 is a schematic diagram of a water treatment device 10 according to an embodiment of the present invention. 1, the water treatment device 10 according to this embodiment includes a treatment tank 1 into which the water to be treated W is introduced via a line L1, an aeration device 2, an agitation device 3, a hydrogen donor adding section 4, a measuring section 5 for measuring the ammonia nitrogen concentration and / or the nitrate nitrogen concentration, and a control section 6. In addition, a water to be treated amount adjusting section 7 for adjusting the amount of the water to be treated W introduced is provided on the line L1. In FIG. 1, the dashed arrows indicate connections that are controllable or inputtable.

[0025] In the water treatment device 10 of this embodiment, the water to be treated W containing nitrogen components that has been introduced into the treatment tank 1 is subjected to intermittent aeration treatment. As shown in Fig. 1, a treatment tank 1 is equipped with an aeration device 2 and an agitation device 3. In addition, activated sludge containing microbial cells such as nitrifying bacteria and denitrifying bacteria is placed in the treatment tank 1. In this treatment tank 1, an intermittent aeration operation is performed in which aeration by the aeration device 2 and agitation by the agitation device 3 are alternately repeated, whereby the nitrogen components in the water W to be treated are treated. More specifically, by operating the aeration device 2 in the treatment tank 1, an aerobic (oxidizing) atmosphere is formed, and an oxidation reaction in which ammonia nitrogen is oxidized to nitrate nitrogen by nitrifying bacteria proceeds. On the other hand, by operating the agitation device 3 in the treatment tank 1, an anaerobic (reducing) atmosphere is formed, and a reduction reaction in which nitrate nitrogen is reduced to nitrogen gas by denitrifying bacteria proceeds. The treated water W1 treated in the treatment tank 1 is discharged to the outside of the system via a line L2. Nitrogen gas generated in the treatment tank 1 is discharged to the outside of the system via a line L3.

[0026] The aeration device 2 is for forming an aerobic atmosphere in the treatment tank 1. The aeration device 2 may be any device capable of supplying gas such as air or oxygen into the treatment tank 1, and the specific structure is not particularly limited. As an example of the aeration device 2, as shown in FIG. 1, an aeration device in which an air diffuser 21 and a blower B are connected may be used. Here, examples of the air diffuser 21 include an air diffuser having a plurality of nozzles, a tubular member made of a porous material, and an air diffuser made of a tubular member or a plate member having a number of holes or slits. In addition, the blower B may be any device capable of compressing and sending gas, and examples of the blower B include a blower and a compressor. As a result, gas is supplied into the treatment tank 1, the treatment tank 1 is made under an aerobic atmosphere, and the nitrification process (oxidation reaction) by the nitrifying bacteria can proceed.

[0027] The agitator 3 is for forming an anaerobic atmosphere in the treatment tank 1 by agitating the water in the treatment tank 1 when the aeration device 2 is stopped. The agitation device 3 is not particularly limited in its specific structure as long as it can agitate the water W to be treated in the treatment tank 1. As an example of the agitation device 3, as shown in Fig. 1, it is possible to use an agitation device including an agitation blade 31, an agitation shaft 32 attached to the agitation blade 31, and a drive mechanism 33 for rotating the agitation blade 31. This allows the treatment tank 1 to be agitated, and the treatment tank 1 to be placed under an anaerobic atmosphere, allowing the denitrification step (reduction reaction) by the denitrifying bacteria to proceed. It should be noted that a structure other than the stirring blade may be used as the stirring device 3. Also, stirring may be performed by a drive mechanism other than rotation.

[0028] The location of the agitator 3 is not particularly limited. As shown in Fig. 1, the agitator blade may be provided from the upper side of the treatment tank 1, or the agitator blade may be provided on the side wall side of the treatment tank 1 or on the bottom side of the treatment tank 1.

[0029] The hydrogen donor adding section 4 is for adding a hydrogen donor to the water W to be treated in the treatment tank 1 . In the reduction reaction in the denitrification process described above, hydrogen is required to proceed with the reaction. Normally, the BOD components in the water W to be treated function as the hydrogen donor, but there may be a shortage depending on the water quality and treatment status of the water W to be treated. For this reason, by providing a hydrogen donor addition section 4 and adding a hydrogen donor to the water W to be treated as necessary, it becomes possible to efficiently proceed with the denitrification process.

[0030] The structure of the hydrogen donor adding unit 4 is not particularly limited. For example, as shown in Fig. 1, the hydrogen donor adding unit 4 may include a storage unit 41 for storing the hydrogen donor, a pipe 42 for adding the hydrogen donor to the treatment tank 1, and an adjustment mechanism 43 provided on the pipe 42 for adjusting the amount of hydrogen donor added. Examples of the adjustment mechanism 43 include a flow rate adjustment valve and a pump. As the hydrogen donor, an easily decomposable organic matter may be used. Examples of such organic matter include alcohol, organic acids such as acetic acid, and sugar-containing waste liquid. In particular, it is preferable to use methanol as the hydrogen donor, which also serves as a carbon source and an energy source for denitrifying bacteria. Furthermore, by using methanol as the hydrogen donor, it becomes easy to calculate the effect on the denitrification process (reduction reaction) according to the amount of addition. This makes it easy for the control unit 6, which will be described later, to control the amount of hydrogen donor added to the water W to be treated.

[0031] The measuring section 5 is for measuring the ammoniacal nitrogen concentration and / or the nitrate nitrogen concentration in the water W to be treated. The measurement unit 5 may be capable of measuring at least either the ammoniacal nitrogen concentration or the nitrate nitrogen concentration, but it is more preferable that the measurement unit 5 is capable of measuring both the ammoniacal nitrogen concentration and the nitrate nitrogen concentration, which improves the accuracy of calculations related to the optimization conditions for the intermittent aeration operation in the control unit 6 described later. The measurement unit 5 may be provided with known measuring instruments as an ammoniacal nitrogen concentration meter and a nitrate nitrogen concentration meter, and may measure the ammoniacal nitrogen concentration and the nitrate nitrogen concentration independently, or may obtain the values ​​of the ammoniacal nitrogen concentration and the nitrate nitrogen concentration by combining either the ammoniacal nitrogen concentration meter or the nitrate nitrogen concentration meter with a total nitrogen concentration meter. Note that known measuring instruments capable of measuring the ammoniacal nitrogen concentration and / or the nitrate nitrogen concentration include those equipped with an ion electrode. Moreover, it is preferable that the measurement unit 5 is capable of continuous measurement and automatic data transmission, which increases the accuracy of calculations in the control unit 6 (described later) and makes it easier to input data to the control unit 6.

[0032] The treated water amount adjusting section 7 is for adjusting the amount of the treated water W to be introduced into the treatment tank 1. The treated water amount adjusting unit 7 may be any unit that can adjust the amount of the treated water W input from the line L1 using the control unit 6 described later. Examples of the treated water amount adjusting unit 7 include a flow rate adjusting valve or a valve provided on the line L1 as shown in Fig. 1, and an inverter control of a treated water transfer device.

[0033] The control unit 6 is for controlling the intermittent aeration operation in the treatment tank 1. As shown in FIG. 1, the control unit 6 is controllably connected to the aeration device 2, the stirring device 3, the hydrogen donor addition unit 4, and the treated water volume adjustment unit 7, which are the objects to be controlled, and is also connected so that the measurement results of the measurement unit 5 can be input.

[0034] The control unit 6 may be any unit capable of controlling or acquiring information about each component connected as a control target. As the control unit 6 in this embodiment, for example, as shown in FIG. 1, there is a unit including an information acquisition unit 61, a calculation unit 62, and an operation control unit 63.

[0035] The information acquiring section 61 acquires data relating to the measurement results in the measuring section 5. The calculation unit 62 performs calculations related to the control of the intermittent aeration operation, such as the driving time of the aeration device 2 for the intermittent aeration operation, the driving time of the agitator 3, the amount of hydrogen donor added by the hydrogen donor adding unit 4, and the input amount of the water W to be treated by the water to be treated amount adjusting unit 7, based on the data acquired by the information acquiring unit 61. The calculations will be described later. Furthermore, the operation control unit 63 includes a calculation unit 6 A control signal based on the calculation result of 2 is sent to each component connected as a controlled object.

[0036] The information acquisition unit 61, the calculation unit 62, and the operation control unit 63 constituting the control unit 6 may include manual operation by an operator, but it is preferable to use a computing device that has a data input / output function for acquiring information and executes a program for performing calculations related to control and transmitting control signals using a processor such as a CPU to enable automatic control. This makes it easy to optimize the intermittent aeration operation of the water treatment device 10.

[0037] (Control of intermittent aeration operation in water treatment equipment) Hereinafter, when using the water treatment device 10 of this embodiment to perform intermittent aeration treatment of water W containing nitrogen components, suitable intermittent aeration operation control according to the nitrogen behavior in the water W will be described by way of example. Note that the explanations and flow charts relating to each operation control are merely examples of the embodiment, and are not limited thereto.

[0038] FIG. 2 is a graph showing a schematic diagram of the measurement results obtained by the measuring section 5 within one cycle of the intermittent aeration operation of the water treatment device 10 of this embodiment. In the intermittent aeration operation of the present invention, a combination of aeration and stirring is defined as one cycle, and the order of aeration and stirring is not particularly limited. In this embodiment, one cycle is shown to be one in which aeration by the aeration device 2 is followed by stirring by the stirring device 3, but this is not limiting, and one cycle may be one in which aeration by the aeration device 2 is followed by stirring by the stirring device 3.

[0039] Figure 2 shows the change over time in ammoniacal nitrogen concentration (Figure 2A) and nitrate nitrogen concentration (Figure 2B) when the treated water W input into the water treatment device 10 is subjected to a nitrification process (oxidation reaction) by driving the aeration device 2, and then a denitrification process (reduction reaction) by driving the agitation device 3. At this time, the initial value of the ammonia nitrogen concentration is C NH4-N0 , the processed value is C NH4-N1 The maximum value during processing is C NH4-Nmax , the minimum value is C NH4-Nmin The initial value of the nitrate nitrogen concentration is C NO3-N0 , the processed value is C NO3-N1 The maximum value during processing is C NO3-Nmax Let us assume that. In addition, the aeration time for the nitrification process is T N0 The mixing time for the denitrification process is T D0 The processing time for one cycle is T0. N0 , T DO The relationship between T0 and T0 is T0=T N0 +T D0 T0 is the predetermined processing time for one cycle, and T N0 , T DO is the reference time for aeration and mixing in the treatment cycle after T0.

[0040] When the data as shown in FIG. 2 is input to the calculation unit 62 via the information acquisition unit 61, the calculation unit 62 calculates the nitrification rate v NMore specifically, the maximum ammonia nitrogen concentration during treatment, C NH4-Nmax and the minimum value C NH4-Nmin Calculate the slope of the initial value C NH4-N0 The start of aeration and the maximum value C NH4-Nmax There is a certain time difference between the treatment times that show the minimum value of ammonia nitrogen concentration C NH4-Nmin is not indicated at the time when aeration is stopped, but after a certain time. Therefore, the maximum value C of the ammonia nitrogen concentration is obtained by using the data measured by the measuring unit 5, not the ammonia nitrogen concentration at the start and end of aeration. NH4-Nmax and the minimum value C NH4-Nmin Based on the slope of N By calculating this, it is possible to accurately grasp the behavior of nitrogen in the treatment tank 1. N The content of the operation control in the next cycle is determined based on the above. The calculations related to this operation control will be described later.

[0041] The obtained nitrification rate v N Based on this, the treatment time T1 of the next cycle and the amount of air supplied by aeration during the treatment time T1 of the next cycle are adjusted. Here, the processing time T1 of the next cycle is treated as a variable value that varies from the predetermined processing time T0 of one cycle. The amount of air to be adjusted at this time is the amount of air required for nitrification, and can be determined based on the aeration time and the performance of the aeration device. For example, if it is necessary to increase the amount of air required for nitrification in the next cycle, the performance of the aeration device is assumed to be constant, and the aeration time T N1 The control is to increase the

[0042] Based on the calculation results of the calculation unit 62, in order to adjust the processing time T1 of the next cycle and the amount of air supplied by aeration during the processing time T1 of the next cycle, the operation control unit 63 transmits control signals related to the driving time of the blower B of the aeration device 2 and the driving time of the drive mechanism 33 of the agitator 3 to each component (the aeration device 2 and the agitator 3). This makes it possible to directly grasp the nitrogen behavior in the water to be treated W, accurately evaluate the treatment status of the water to be treated W, and then precisely control the nitrogen in the water to be treated W, thereby optimizing the intermittent aeration operation.

[0043] The data used by the calculation unit 62 is not limited to data based on the value of the ammonia nitrogen concentration as described above, but data based on the value of the nitrate nitrogen concentration may be used as data to perform similar calculation processing and control the intermittent aeration operation. For example, based on the correlation between the ammonia nitrogen concentration and the nitrate nitrogen concentration in one cycle, the nitrification rate v N It may be assumed that the following is required:

[0044] In this embodiment, it is preferable to perform a calculation process using the values ​​of the ammoniacal nitrogen concentration and the nitrate nitrogen concentration. This makes it possible to optimize the intermittent aeration operation by grasping the nitrogen behavior in the water W to be treated in more detail.

[0045] FIG. 3 is a flow diagram showing the control of the control unit 6 in the water treatment device 10 of this embodiment, and is a flow diagram for the case where both the ammoniacal nitrogen concentration and the nitrate nitrogen concentration are measured in the measurement unit 5 and the measurement results are input to the information acquisition unit 61. Moreover, FIG. 3 mainly shows the control related to the nitrification process.

[0046] First, in the treatment time T0 of one cycle, the aeration time T N0 , mixing time T D0 Then, the data on the ammoniacal nitrogen concentration and the nitrate nitrogen concentration obtained by the measurement unit 5 is input to the calculation unit 62 via the information acquisition unit 61. Here, the maximum ammonia nitrogen concentration C NH4-Nmax and the minimum value C NH4-Nmin From the slope of the equation, the nitrification rate v N Calculate. In addition, the minimum value of the ammonia nitrogen concentration C NH4-Nmin and the minimum value C' of the ammonia nitrogen concentration during the treatment one cycle beforeNH4-Nmin The difference ΔC NH4-Nmin is calculated.

[0047] Next, the value of this difference ΔC NH4-Nmin is compared with the set values X1 and X2, and value classification is performed based on this comparison. As shown in FIG. 3, this value classification is ΔC NH4-Nmin < X2, X2 ≤ ΔC NH4-Nmin ≤ X1, X1 < ΔC NH4-Nmin and is divided into three categories. Note that the set values X1 and X2 correspond to the variation in the ammonia nitrogen concentration allowed within one cycle or the measurement error of the ammonia nitrogen concentration, and the relationship X1 > X2 holds. Also, usually, X1 and X2 have the same absolute value and are in a positive-negative relationship, but it is not limited to this, and those with different absolute values of X1 and X2 may be set. The set values X1 and X2 can be appropriately determined based on past processing results and the like.

[0048] The difference ΔC NH4-Nmin Based on the value classification in the comparison of the value of ΔC with the set values X1 and X2, the aeration time T in the processing time T1 of the next cycle N1 is adjusted to increase or decrease with respect to the aeration time T N0 . As a result, it becomes possible to adjust the processing time T1 of the next cycle and the amount of air supplied by aeration in the processing time T1 of the next cycle.

[0049] As shown in FIG. 3, when the value classification related to the difference ΔC NH4-Nmin is ΔC NH4-Nmin < X2, it is determined that there is room for processing in the nitrification process, and the aeration time T N1 is adjusted to decrease compared to the aeration time T N0 . Also, when the value classification related to the difference ΔC NH4-Nmin is X1 < ΔC NH4-Nmin , it is determined that the processing in the nitrification process is not sufficient, and the aeration time T N1 is adjusted to increase compared to the aeration time T N0 . On the other hand, when the value classification related to the difference ΔC NH4-Nmin is X2 ≤ ΔC NH4-Nmin ≤ X1, the aeration time TN1 is the aeration time T N0 is the same as, that is, the aeration time T N0 is adjusted to be maintained without change from

[0050] And, X1 < ΔC NH4-Nmin and ΔC NH4-Nmin < X2, in this case, the variation in aeration time for adjusting the aeration time T N1 is calculated by the following formula 1.

Equation

[0051] X1 < ΔC NH4-Nmin In the case of, the variation in aeration time obtained based on formula 1 is added to the aeration time T N0 to obtain the calculated aeration time T N1-C1 . Then, the obtained calculated aeration time T N1-C1 is compared with the maximum aeration time T Nmax set as the upper limit of the aeration time. T N1-C1 ≤ T Nmax In the case of, the aeration time T N1 in the next one-cycle treatment time T1 is as per the calculation result based on formula 1, T N1 = T N1-C1 is set. On the other hand, T Nmax < T N1-C1 In the case of, the aeration time T N1 in the next one-cycle treatment time T1 is, T N1 = T Nmax is set. And, so that the value of ΔC NH4-Nmin falls within a predetermined range, instead of adjusting the aeration time, the input amount of the water to be treated is adjusted. That is, the input amount of the water to be treated is adjusted to decrease so that X2 ≤ ΔC NH4-Nmin ≤ X1 holds.

[0052] Also, ΔC NH4-Nmin In the case of <X2, the variation in aeration time obtained based on Equation 1 is subtracted from the aeration time T N0 to obtain the calculated aeration time T N1-C2 Then, the calculated aeration time T N1-C2 is compared with the minimum small aeration time T Nmin set as the lower limit of the aeration time. T N1-C2 > T Nmin If so, the aeration time T N1 in the next cycle of the processing time T1 is set to T N1 = T N1-C2 as per the calculation result based on Equation 1. On the other hand, if T Nmin ≧ T N1-C2 If so, the aeration time T N1 in the next cycle of the processing time T1 is set to T N1 = T Nmin Then, the input amount of the water to be treated is adjusted instead of the aeration time so that the value of ΔC NH4-Nmin falls within a predetermined range. That is, the input amount of the water to be treated is adjusted to increase such that X2 ≤ ΔC NH4-Nmin ≤ X1 holds.

[0053] Also, as shown in FIG. 3, when T N1 = T N0 or when T N1 varies as per the calculation result based on Equation 1, the adjustment of the input amount of the water to be treated becomes unnecessary.

[0054] Regarding the adjustment of the input amount of the water to be treated, based on the flowchart shown in FIG. 3, the operation control unit 63 issues a control signal related to the drive (opening / closing) of the water to be treated amount adjustment unit 7. Thereby, the amount of the water to be treated W input from the line L1 can be adjusted.

[0055] In this way, by performing calculations based on the nitrification rate and the minimum value (maximum value) of the ammonia nitrogen concentration, the aeration time T N1 in the next cycle of the processing time T1 is set as the aeration time TN0 It is possible to calculate an appropriate aeration time variation when making an adjustment to vary the aeration time from the aeration time. It is also possible to avoid making an aeration time adjustment that exceeds the capacity of the aeration device 2. Furthermore, by adjusting not only the aeration time but also the input amount of the water to be treated, it is possible to perform intermittent aeration operation without reducing the treatment capacity in the nitrification process.

[0056] Fig. 4 shows a flow diagram relating to the control of the control unit 6 in the water treatment device 10 of this embodiment. Fig. 4 also shows the control mainly relating to the denitrification process. Note that the part surrounded by the dashed line in Fig. 4 shows the common part with the flowchart shown in Fig. 3.

[0057] First, in the treatment time T0 of one cycle, the aeration time T N0 , mixing time T D0 Then, as the data of the ammonia nitrogen concentration and the nitrate nitrogen concentration obtained by the measurement unit 5, the processed value C of the nitrate nitrogen concentration is NO3-N1 is input to the calculation unit 62 via the information acquisition unit 61.

[0058] Next, in the calculation unit 62, the processed value C of the nitrate nitrogen concentration is calculated. NO3-N1 and the preset value C NO3-SVmax and C NO3-SVmin The set value C is compared with the set value C. NO3-SVmax and C NO3-SVmin These indicate the maximum and minimum values ​​that indicate that the nitrate nitrogen concentration is within the appropriate range after one treatment cycle has elapsed, and are appropriately determined based on past treatment results, etc. In addition, the value C after treatment NO3-N1 and setting value C NO3-SVmax and C NO3-SVminBy comparing the amount of denitrification treatment required in the treatment time T1 of the next cycle with the amount of denitrification treatment required in the next cycle, it is possible to determine the amount of denitrification treatment required in the treatment time T1 of the next cycle. Then, the control unit 6 adjusts the mixing time, etc. to control this amount of denitrification treatment. Here, control of the amount of denitrification treatment relates to an increase or decrease in the amount of denitrification treatment within the treatment time of one cycle, and mainly refers to reducing the amount of denitrification treatment by intermittent aeration operation. The amount of denitrification treatment can be controlled, for example, by adjusting the post-treatment value C NO3-N1 is the set value C NO3-SVmax The amount exceeding this corresponds to an additional amount to the denitrification treatment amount that needs to be processed in the treatment time T1 of the next cycle, and the mixing time, etc. should be adjusted so that treatment can be performed taking this additional amount into account.

[0059] Nitrate nitrogen concentration after treatment C NO3-N1 and the preset value C NO3-SVmax and C NO3-SVmin Based on the value classification by comparison with the above, the time required to process the denitrification treatment amount, i.e., the mixing time T D1 Adjustments will be made.

[0060] As shown in Figure 4, NO3-N1 C NO3-SVmin Less Than (C NO3-N1 <C NO3-SVmin ), it is determined that the denitrification process is proceeding excessively, and the mixing time T D1 is the mixing time T D0 The amount of hydrogen donor added is adjusted so as to stop its addition. NO3-N1 C NO3-SVmin and C. NO3-SVmax Between (C NO3-SVmin ≦C NO3-N1 ≦C NO3-SVmax ), it is determined that the denitrification process is proceeding properly, and the mixing time T D1 is the mixing time T D0 That is, the mixing time T D0 The amount of hydrogen donor added is also adjusted so as to remain unchanged. Furthermore, CNO3-N1 C NO3-SVmax Greater Than (C NO3-SVmax <C NO3-N1 ), it is determined that the treatment in the denitrification step is insufficient, and the mixing time T D1 Adjust to increase.

[0061] C NO3-N1 C NO3-SVmax Greater Than (C NO3-SVmax <C NO3-N1 ) if mixing time T D1 The adjustment by increasing the aeration time T N1 For example, the aeration time T N1 The mixing time T is increased to a predetermined multiple N (for example, N=2) minutes. D1 Increasing the mixing time T D1 With the increase in NO3-N1 C NO3-SVmax If the mixing time T D1 is the aeration time T N1 Even if it becomes larger than a certain multiple N of C NO3-N1 C NO3-SVmax If the mixing time T D1 Instead, the amount of hydrogen donor added is increased to promote the reaction required for treating the denitrification amount.

[0062] Regarding the adjustment of the amount of hydrogen donor added, the operation control unit 63 transmits a control signal related to the drive of the adjustment mechanism 43 in the hydrogen donor adding unit 4 based on the flowchart shown in Fig. 4. This makes it possible to adjust the amount of hydrogen donor added from the storage unit 41 via the pipe 42. In this case, the adjustment of the amount of hydrogen donor added can be performed based on Equation 2. Equation 2 indicates the drive time of the adjustment mechanism 43 (pump) that adds methanol as the hydrogen donor.

number

[0063] Also, C NO3-N1 C NO3-SVmin Less Than (C NO3-N1 <C NO3-SVmin ) in the case where the aeration time T N1 Mixing time T based on the value multiplied by a specified multiple N D1 For example, the aeration time T N1 The mixing time T is increased to a predetermined multiple N (for example, N=1) of D1 This makes it possible to reduce the processing time T1 while maintaining the required processing efficiency, thereby reducing the cost associated with the processing.

[0064] In this way, by using the post-treatment value of the nitrate nitrogen concentration and performing a calculation that grasps the denitrification treatment amount, the behavior of nitrogen in the water W to be treated can be grasped more accurately and the treatment state of the water W to be treated can be evaluated. Furthermore, by adjusting the mixing time based on this evaluation, nitrogen in the water to be treated can be finely controlled, and the intermittent aeration operation can be optimized. Furthermore, by using a predetermined multiple of the aeration time as a reference in adjusting the mixing time, it is possible to avoid needlessly extending the treatment time of the intermittent aeration operation. Furthermore, by adjusting not only the mixing time but also the amount of hydrogen donor added, it is possible to perform intermittent aeration operation without reducing the treatment capacity in the denitrification process.

[0065] The data used in the control based on Figures 3 and 4 may be related to the ammonia nitrogen concentration or the nitrate nitrogen concentration, and is not limited to the above. The data used in each control can be selected according to the order of stirring and aeration in one cycle, the relationship between the ammonia nitrogen concentration and the nitrate nitrogen concentration (conversion by treatment), etc. For example, the nitrification process may be controlled based on the maximum or minimum value of the nitrate nitrogen concentration during treatment. The denitrification process may be controlled using the value of the ammonia nitrogen concentration after treatment. Furthermore, the nitrification process and the denitrification process may be controlled by performing a calculation taking into account data on both the ammonia nitrogen concentration and the nitrate nitrogen concentration.

[0066] As described above, the water treatment device 10 of this embodiment is provided with a control unit, and by calculating the nitrification rate for each cycle, it is possible to directly grasp the behavior of nitrogen in the water to be treated and accurately evaluate the treatment state of the water to be treated. In addition, by adjusting the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the calculation results, it is possible to finely control the nitrogen in the water to be treated and optimize the intermittent aeration operation.

[0067] Furthermore, in the water treatment device 10 of this embodiment, the control unit adjusts not only the treatment time for the next cycle and the amount of air supplied by aeration during the treatment time for the next cycle, but also the amount of water to be treated and the amount of hydrogen donor added, thereby enabling precise control of nitrogen in the water to be treated and optimizing intermittent aeration operation.

[0068] The above-described embodiment shows an example of a water treatment device and a water treatment method. The water treatment device and the water treatment method according to the present invention are not limited to the above-described embodiment, and the water treatment device and the water treatment method according to the above-described embodiment may be modified without departing from the gist of the present invention.

[0069] The water treatment device of this embodiment is not limited to a device that performs treatment in one tank (single tank) as long as it performs intermittent aeration operation that repeats agitation and aeration. For example, it may perform intermittent aeration operation based on the control of this embodiment for multiple tanks. This makes it possible to increase the amount of water to be treated that can be treated within a given time, thereby improving the treatment efficiency. [Industrial Applicability]

[0070] The water treatment apparatus and method of the present invention are preferably used for treating water containing nitrogen components, particularly in nitrification / denitrification treatment in which nitrogen components in the water are removed by intermittent aeration operation. [Explanation of symbols]

[0071] 10 water treatment device, 1 treatment tank, 2 aeration device, 21 aeration body, 3 mixing device, 31 mixing blade, 32 mixing shaft, 33 drive mechanism, 4 hydrogen donor addition section, 41 storage section, 42 piping, 43 adjustment mechanism, 5 measurement section, 6 control section, 61 information acquisition section, 62 calculation section, 63 operation control section, 7 treated water amount adjustment section, B blower, L1 to L3 lines, W treated water, W1 treated water

Claims

1. A water treatment device that removes nitrogen components from water to be treated by intermittent aeration operation, The system includes a control unit which calculates a nitrification rate during a predetermined treatment time of one cycle, and adjusts the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the calculated nitrification rate, The control unit calculates a calculated aeration time based on the obtained nitrification rate, and adjusts the amount of water to be treated by comparing the calculated aeration time with a predetermined aeration time.

2. A water treatment device that removes nitrogen components from water to be treated by intermittent aeration operation, The system is provided with a control unit which calculates a nitrification rate during a predetermined treatment time of one cycle, with an operation relating to aeration and stirring being one cycle, and adjusts the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the calculated nitrification rate, The water treatment device according to claim 1, wherein the control unit adjusts a mixing time based on a value of an ammoniacal nitrogen concentration and / or a value of a nitrate nitrogen concentration at the end of one treatment cycle.

3. 3. The water treatment device according to claim 1, wherein the control unit adjusts an amount of hydrogen donor added to control an amount of denitrification treatment.

4. A water treatment method for removing nitrogen components from water to be treated by intermittent aeration operation, comprising: The method includes a control step of calculating a nitrification rate during a predetermined treatment time of one cycle, the control step being one cycle of operations related to stirring and aeration, and adjusting the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the calculated nitrification rate, The water treatment method is characterized in that the control step includes calculating a calculated aeration time based on the obtained nitrification rate, and adjusting the amount of water to be treated by comparing the calculated aeration time with a predetermined aeration time.

5. A water treatment method for removing nitrogen components from water to be treated by intermittent aeration operation, comprising: The method includes a control step of calculating a nitrification rate during a predetermined treatment time of one cycle, the control step being one cycle of operations related to stirring and aeration, and adjusting the treatment time of the next cycle and the amount of air supplied by aeration during the treatment time of the next cycle based on the calculated nitrification rate, The water treatment method, wherein the control step includes adjusting the stirring time based on the value of the ammoniacal nitrogen concentration and / or the nitrate nitrogen concentration at the end of one cycle of treatment time.

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