Multi-layer treatment tank and wastewater treatment system

Abstract

To realize a double layer type processing tank capable of separating an exhaust gas in an anoxic tank and an exhaust gas in an aerobic tank with a plurality of tanks vertically arranged, and a sewage treatment system.SOLUTION: A multi-layer processing tank 1 comprising an aerobic tank 2 provided at an upper layer and an anoxic tank 3 provided at a lower layer, comprises: a first communication passage 4 provided over the aerobic tank 2 and the anoxic tank 3; a second communication passage 6 provided over the anoxic tank 3 and a tank different from the anoxic tank 3; and a biasing device 5 capable of biasing fluid. The first communication passage 4 and the biasing device 5 are arranged such that when the biasing device 5 is operated, a flow W4 flowing into the anoxic tank 3 through the first communication passage 4 from the aerobic tank 2 is formed. One end 61 of the second communication passage 6 opens at an upper surface 31 of the anoxic tank 3. At one end 42 of the first communication passage 4, a wall surface defining the first communication passage 4 projects from the upper surface 31 of the anoxic tank 3 to the inside of the anoxic tank 3.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a multi-layer treatment tank and a wastewater treatment system including a plurality of such multi-layer treatment tanks. [Background technology]

[0002] Conventionally, a method of using activated sludge to treat water to be treated, such as domestic wastewater, has been adopted that utilizes a combination of multiple biological treatments. In this type of method, in order to utilize multiple microorganisms that are active in different environments, a method is generally used in which multiple tanks with different environments (aerobic tank, anoxic tank, anaerobic tank, etc.) are provided, and the water to be treated is circulated between these multiple tanks while biological treatment is applied in each tank. In other words, in the biological treatment of wastewater, it is common to provide multiple treatment tanks.

[0003] As an attempt to reduce the area required for installing multiple treatment tanks, JP 2020-54980 A (Patent Document 1) discloses an organic wastewater treatment device in which an aerobic tank and an anoxic tank are arranged one above the other. This technology has succeeded in reducing the area required for installing these two treatment tanks by arranging the aerobic tank and the anoxic tank one above the other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-54980 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the anoxic tank, nitrate ions are decomposed by denitrifying bacteria to generate nitrogen gas. The exhaust gas from the anoxic tank containing this nitrogen gas has an odor, and therefore needs to be deodorized. However, the device of Patent Document 1 is configured so that the gas (nitrogen gas) generated in the anoxic tank is released into the atmosphere through the aerobic tank, and therefore the exhaust gas from the aerobic tank may have an odor. This has resulted in the need to apply deodorization treatment to the exhaust gas from the aerobic tank, which did not previously require deodorization treatment, and has led to an increase in the required capacity of the deodorization equipment.

[0006] In addition, by measuring the state of the exhaust gas generated from the anoxic tank, it is possible to infer the reaction state within the anoxic tank. However, in the device of Patent Document 1, the exhaust gas from the anoxic tank is mixed with the exhaust gas from the aerobic tank, so it is not possible to measure the exhaust gas from the anoxic tank separately.

[0007] Therefore, there is a need to realize a multi-layer treatment tank and wastewater treatment system that can separate exhaust gas from the anoxic tank and exhaust gas from the aerobic tank while arranging multiple tanks one above the other. [Means for solving the problem]

[0008] The multi-layer treatment tank of the present invention is a multi-layer treatment tank comprising an aerobic tank provided in an upper layer and an anoxic tank provided in a lower layer, and has a first communicating passage provided between the aerobic tank and the anoxic tank, a second communicating passage provided between the anoxic tank and a tank other than the anoxic tank, and a biasing device capable of biasing a fluid, wherein the first communicating passage and the biasing device are arranged such that, when the biasing device is operated, a flow is formed flowing from the aerobic tank through the first communicating passage into the anoxic tank, one end of the second communicating passage opens into an upper surface of the anoxic tank, and at one end of the first communicating passage, a wall surface defining the first communicating passage protrudes from the upper surface of the anoxic tank into the interior of the anoxic tank.

[0009] Further, a wastewater treatment system according to the present invention is a wastewater treatment system comprising a plurality of multi-layer treatment tanks each having an aerobic tank provided in an upper layer, an anoxic tank provided in a lower layer, a first communication passage provided between the aerobic tank and the anoxic tank, and a biasing device capable of biasing a fluid, the plurality of multi-layer treatment tanks forming a circulation system in which the aerobic tanks and the anoxic tanks are alternately connected, the first communication passage and the biasing device are arranged such that, when the biasing device is operated, a flow is formed that flows from the aerobic tank through the first communication passage into the anoxic tank, and at one end of the first communication passage, a wall surface that defines the first communication passage protrudes from an upper surface of the anoxic tank into the anoxic tank, and two adjacent multi-layer treatment tanks in the circulation system are connected by a second communication passage provided between the anoxic tank of one of the multi-layer treatment tanks and the aerobic tank of the other multi-layer treatment tank, one end of the second communication passage opens into an upper surface of the anoxic tank, each of the second communication passages has a protruding portion protruding above an upper edge of the aerobic tanks of the two multi-layer treatment tanks connected by the second communication passage, the upper surface of the protruding portion is closed by a face piece having an opening, a third communication passage is connected to the opening, and each of the third communication passages is provided with a flow velocity meter capable of measuring the flow velocity of gas flowing through the third communication passage.

[0010] With these configurations, the exhaust gas from the anoxic tank can be separated from the exhaust gas from the aerobic tank while arranging multiple tanks one above the other. This is because, at one end of the first communication passage, the wall surface defining the first communication passage protrudes from the top surface of the anoxic tank into the inside of the anoxic tank, and the biasing device constantly generates a downward water flow, making it difficult for gas generated in the anoxic tank to flow into the first communication passage. In addition, because gas is unlikely to flow into the first communication passage, the flow from the aerobic tank to the anoxic tank is not easily obstructed.

[0011] Preferred embodiments of the present invention will be described below. However, the scope of the present invention is not limited to the preferred embodiments described below.

[0012] In one aspect of the multi-layer treatment tank of the present invention, the upper surface of the anoxic tank is inclined, and one end of the second communication passage is preferably provided at the upper end portion of the inclined upper surface.

[0013] According to this configuration, the gas generated in the anoxic tank can be more suitably collected in the second communication passage.

[0014] In one aspect of the multi-layer treatment tank of the present invention, the first communication passage has a tubular portion extending into the aerobic tank, a standard liquid level which is the liquid level under normal operating conditions is set in the aerobic tank, and the biasing device has a power section provided above the standard liquid level, and a biasing section provided below the standard liquid level and driven by the power of the power section to bias the fluid, and it is preferable that the biasing section is housed in the tubular portion.

[0015] According to this configuration, the flow from the aerobic tank to the anoxic tank is regulated by the tubular portion, so that the power of the biasing device can be efficiently consumed in moving the water to be treated. Also, since the power unit is installed above the standard liquid level, maintenance of the power unit can be facilitated.

[0016] In one embodiment, the multi-layer treatment tank of the present invention preferably further has a pit surrounding the portion of the upper surface of the anoxic tank where one end of the second communicating passage is open, and an aeration pipe connected to the pit.

[0017] According to this configuration, an air lift effect is created by the gas released into the second communication passage (gas generated in the anoxic tank), promoting flow downstream through the second communication passage, thereby making it possible to reduce the power required to input to circulate the treated water.

[0018] In one embodiment of the multi-layer treatment tank according to the present invention, the aeration pipe is preferably further connected to a water supply source.

[0019] According to this configuration, the air diffusion tube can be easily cleaned, so that the air diffusion tube is less likely to become clogged. Even if the air diffusion tube does become clogged, the clog is easily removed.

[0020] In one aspect of the multi-layer treatment tank of the present invention, the second communication passage has a protruding portion protruding above an upper edge of the aerobic tank, the upper surface of the protruding portion is closed by a face piece having an opening, a third communication passage is connected to the opening, and the third communication passage is preferably provided with a flow rate meter capable of measuring the flow rate of gas flowing through the third communication passage.

[0021] According to this configuration, the flow rate of the exhaust gas in the anoxic tank can be measured accurately and continuously. This allows the reaction state in the anoxic tank to be grasped accurately and in a timely manner. In addition, the required capacity of the deodorization equipment can be determined based on the actual flow rate of the exhaust gas, so that the required capacity can be optimized. Furthermore, the exhaust gas continuously generated in the anoxic tank itself pushes out the previously generated exhaust gas downstream of the third communication passage, so that the power for guiding the exhaust gas to the deodorization equipment can be omitted.

[0022] In one aspect of the multi-layer treatment tank according to the present invention, a nozzle capable of spraying water is preferably provided on the inside of the protruding portion.

[0023] According to this configuration, by spraying water from the nozzle toward the liquid surface in the protruding portion, accumulation of scum in the protruding portion can be suitably prevented.

[0024] In one aspect, the multi-layer treatment tank of the present invention further includes a control device configured to acquire at least one parameter selected from the group consisting of a raw water inflow rate, which is the flow rate of raw water flowing into the anoxic tank, a raw water measurement value, which is a measurement value related to the quality of the raw water, a treated water outflow rate, which is the flow rate of treated water flowing out of the aerobic tank, a treated water measurement value, which is a measurement value related to the quality of the treated water flowing out of the aerobic tank, an anoxic tank water temperature, which is the water temperature of the anoxic tank, an aerobic tank water temperature, which is the water temperature of the aerobic tank, and a flow velocity of a fluid flowing through the second communication passage, and an outflow gas volume, which is a measurement value of the flow rate meter. It is preferable that the control device is configured to execute an acquisition process for acquiring a data set of the at least one parameter at a certain time and the outflow gas volume at the same time, a data group construction process for accumulating the data sets for a plurality of times to construct a data group, and a learning process for constructing a classifier based on the data group that can output a predicted value of the outflow gas volume predicted based on the at least one parameter when the at least one parameter is input.

[0025] According to this configuration, it is possible to predict the amount of outflow gas based on various measured values, which makes it possible to predict changes in the operating state of the multi-layer treatment tank, and therefore to take measures early to prevent the occurrence of undesirable changes.

[0026] In one aspect of the sewage treatment system according to the present invention, the second communication passage has a downward portion extending downward from the protruding portion to the other end which opens into the aerobic tank, and is preferably configured such that when the biasing device is operating, the flow velocity of the fluid in the downward portion is 0.8 m per second or less.

[0027] According to this configuration, the gas to be separated in the protruding portion is less likely to be caught in the flow toward the downstream aerobic tank, making it easier to separate the gas.

[0028] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which are given with reference to the drawings. [Brief description of the drawings]

[0029] [Figure 1] 1 is a diagram showing a configuration of a wastewater treatment system according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the configuration of a multi-layer treatment tank according to an embodiment. [Diagram 3] FIG. 2 is a block diagram showing a control configuration of the multi-layer treatment tank according to the embodiment. [Figure 4] FIG. 2 is a block diagram showing an example of a control configuration of the wastewater treatment system according to the embodiment. [Diagram 5] FIG. 2 is a block diagram showing an example of a control configuration of the wastewater treatment system according to the embodiment. [Figure 6] FIG. 13 is a diagram showing a first modified example of a first communication hole. [Figure 7] FIG. 11 is a diagram showing a second modified example of the first communication hole. [Figure 8] FIG. 13 is a diagram showing a third modified example of a first communication hole. [Figure 9] FIG. 13 is a view showing a fourth modified example of a first communication hole. [Figure 10] FIG. 13 is a diagram showing another embodiment of the multi-layer treatment tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The embodiments of the multi-layer treatment tank and the wastewater treatment system according to the present invention will be described with reference to the drawings. In the following, a wastewater treatment system 100 (FIG. 1) equipped with four multi-layer treatment tanks 1 (1A, 1B, 1C, 1D) will be described as an example.

[0031] [Configuration of wastewater treatment system] In the wastewater treatment system 100, a multi-layer treatment tank 1A, a multi-layer treatment tank 1B, a multi-layer treatment tank 1C, and a multi-layer treatment tank 1D are connected in this order, and further, a multi-layer treatment tank 1A is connected downstream of the multi-layer treatment tank 1D, forming a circulation system for activated wastewater treatment by a circulating nitrification / denitrification method (Figure 1). More specifically, in the sewage treatment system 100, the water to be treated flows in the following order: aerobic tank 2A ​​of the multi-layer treatment tank 1A, anoxic tank 3A of the multi-layer treatment tank 1A, aerobic tank 2B of the multi-layer treatment tank 1B, anoxic tank 3B of the multi-layer treatment tank 1B, aerobic tank 2C of the multi-layer treatment tank 1C, anoxic tank 3C of the multi-layer treatment tank 1C, aerobic tank 2D of the multi-layer treatment tank 1D, and anoxic tank 3D of the multi-layer treatment tank 1D. Furthermore, the aerobic tank 2A ​​of the multi-layer treatment tank 1A is connected downstream of the anoxic tank 3D of the multi-layer treatment tank 1D, forming a circulation system.

[0032] [Configuration of multi-layer treatment tank] The multi-layered treatment tank 1 according to this embodiment is a two-layered wastewater treatment tank including an aerobic tank 2 in the upper layer and an anoxic tank 3 in the lower layer (FIG. 2). In the aerobic tank 2, the treated water is aerated, and ammonia nitrogen is decomposed into nitrate ions by nitrifying bacteria. In the anoxic tank 3, nitrate ions are decomposed into nitrogen gas by denitrifying bacteria. In this way, the multi-layered treatment tank 1 is a facility for decomposing organic nitrogen contained in the raw water W1 (such as domestic wastewater) by combining the decomposition of ammonia nitrogen in the aerobic tank 2 and the decomposition of nitrate ions in the anoxic tank 3. A control device 20 for controlling the operation of each part of the multi-layered treatment tank 1 is provided (FIG. 3). Specifically, the control device 20 is implemented as a computer.

[0033] Although details will be described later, in this embodiment, in a multi-layer treatment tank 1, denitrified water W3 that has been subjected to denitrification treatment in the anoxic tank 3 of a certain multi-layer treatment tank 1 (for example, multi-layer treatment tank 1A) is transferred to the aerobic tank 2 of an adjacent multi-layer treatment tank 1 (for example, multi-layer treatment tank 1B). In addition, nitrified liquid W4 that has been subjected to nitrification treatment in the aerobic tank 2 of the multi-layer treatment tank 1 (for example, multi-layer treatment tank 1B) is transferred to the anoxic tank 3 of the same multi-layer treatment tank 1 (for example, multi-layer treatment tank 1B).

[0034] (Configuration of aerobic tank) The aerobic tank 2 is a tank provided in the upper part of the multi-layer treatment tank 1. The aerobic tank 2 is provided with multiple membrane separation devices 21. Therefore, the multi-layer treatment tank 1 is used for a membrane bioreactor (MBR) process. The treated water W2 that has passed through the membrane separation devices 21 is sent to the next process. A standard liquid level is set in the aerobic tank 2, which is the liquid level in the normal operating state of the multi-layer treatment tank 1, and the membrane separation devices 21 are provided below the standard liquid level. In FIG. 2, the standard liquid level is indicated by a dashed line H. Denitrified water W3 that has been treated in another multi-layer treatment tank 1 located upstream flows into the aerobic tank 2, where ammonia nitrogen is decomposed by nitrifying bacteria. The aerobic tank 2 is provided with an aeration device (not shown).

[0035] In the center of the aerobic tank 2, a draft tube 4 (an example of a first communication passage, an example of a tubular part) and an agitator 5 (an example of an actuator) are provided.

[0036] The draft tube 4 is a cylindrical member extending vertically in the central portion of the aerobic tank 2, and is provided in fluid communication between the aerobic tank 2 and the anoxic tank 3. An upper end 41 of the draft tube 4 opens near the standard liquid level and below the standard liquid level (for example, at a position where the height from the bottom surface 22 of the aerobic tank 2 is 4 / 5 of the standard liquid level). A lower end 42 of the draft tube 4 opens into the anoxic tank 3.

[0037] The agitator 5 has a motor 51 (an example of a power unit), an impeller 52 (an example of a biasing unit), and a shaft member 53. The motor 51 has an inverter and can be controlled by the main power. The control device 20 is configured to be able to output a control signal to the agitator 5 (motor 51), and the output of the motor 51 is controlled by the control signal. The motor 51 is provided above the standard liquid level, and therefore, in the normal operating state of the multi-layered treatment tank 1, the motor 51 is provided above the liquid level. Therefore, the motor 51 does not need to be a device that can be driven underwater, and may be a general motor used in the atmosphere. In addition, while a submersible pump conventionally used in this type of treatment tank requires the work of pulling it out of the water during maintenance, in this embodiment, the motor 51 is provided in the atmosphere, and therefore maintenance of the motor 51 is easy.

[0038] The impeller 52 is provided below the standard liquid level and is attached in a position such that it urges the liquid in the aerobic tank 2 downward when driven by the power of the motor 51. The shaft member 53 is a member that transmits the power of the motor 51 to the impeller 52.

[0039] The impeller 52 is housed in the draft tube 4. Therefore, when the agitator 5 is operated, a downward flow of the nitrification liquid W4 is formed inside the draft tube 4. As a result, a flow of the nitrification liquid W4 flowing from the aerobic tank 2 through the draft tube 4 into the anoxic tank 3 is formed.

[0040] (Configuration of anoxic tank) The anoxic tank 3 is a tank provided in the lower part of the multi-layer treatment tank 1, and is a tank that receives the raw water W1 that flows into the multi-layer treatment tank 1. The raw water W1 and the nitrification liquid W4 transferred from the aerobic tank 2 flow into the anoxic tank 3, and nitrate ions are decomposed by denitrifying bacteria to generate nitrogen gas.

[0041] A lower end 42 of the draft tube 4 and a lower end 61 (an example of one end of the second communication passage) of the denitrification water passage 6 (an example of a second communication passage) are disposed on the upper surface 31 of the anoxic tank 3. Of these, the lower end 42 of the draft tube 4 (an example of one end of the first communication passage) protrudes from the upper surface 31 into the inside of the anoxic tank 3. That is, at the lower end 42 of the draft tube 4, a wall surface (a substantial portion of the draft tube 4 in this case) that defines the passage (a passage portion of the draft tube 4 in this case) protrudes from the upper surface 31 of the anoxic tank 3 into the inside of the anoxic tank 3.

[0042] The upper surface 31 of the anoxic tank 3 is inclined with respect to the horizontal direction. More specifically, the inclination of the upper surface 31 with respect to the horizontal direction is preferably 1° or more and 20° or less. The lower end 61 of the denitrification water passage 6 is provided at the upper end portion of such inclination. As a result, the gas (nitrogen gas, etc.) generated in the anoxic tank 3 flows upward along the inclination of the upper surface 31 and reaches the lower end 61 of the denitrification water passage 6. At this time, since the lower end 42 of the draft tube 4 protrudes from the upper surface 31 into the inside of the anoxic tank 3, the gas flowing along the inclination of the upper surface 31 is unlikely to flow into the lower end 42 of the draft tube 4. Furthermore, it is preferable to configure the upper surface 31 in a flat shape without unevenness, since this can suppress the retention of scum.

[0043] More specifically, a pit 7 is provided at the upper end portion of the upper surface 31, and gas flowing upward along the slope of the upper surface 31 is collected in the pit 7. An aeration pipe 8 is connected to the pit 7, and the gas collected in the pit 7 flows into the denitrified water flow path 6 through the fine holes 81 of the aeration pipe 8. This creates an air lift effect due to the gas released into the denitrified water flow path 6, promoting the flow in the downstream direction, and therefore the power to be input for circulating the water to be treated in the wastewater treatment system 100 (specifically, input as the power of the motor 51) can be reduced.

[0044] In addition, the other end of the aeration pipe 8 (opposite the end connected to the pit 7) is connected to a water source (not shown), and by supplying water from the water source, the pores 81 of the aeration pipe 8 can be cleaned.

[0045] (Configuration of denitrification water flow path) The denitrification water flow path 6 is a flow path provided between the anoxic tank 3 and the outside of the multi-layer treatment tank 1. In this embodiment, the downstream side of the denitrification water flow path 6 is connected to the aerobic tank 2 of the multi-layer treatment tank 1 adjacent to the downstream side in the wastewater treatment system 100. For example, the denitrification water flow path 6 is provided between the anoxic tank 3 of the multi-layer treatment tank 1A and the aerobic tank 2 of the multi-layer treatment tank 1B. Through the denitrification water flow path 6, the denitrification water W3 is transferred from the anoxic tank 3 of the multi-layer treatment tank 1A to the aerobic tank 2 of the multi-layer treatment tank 1B. In addition, the gas generated in the anoxic tank 3 flows into the denitrification water flow path 6 and flows through the denitrification water flow path 6 together with the denitrification water W3.

[0046] The denitrification water flow path 6 has an upward portion 62 extending upward from the upper surface of the anoxic tank 3, a protruding portion 63 protruding above the upper end of the aerobic tank 2, and a downward portion 64 extending downward from the protruding portion 63 along the connected aerobic tank 2, and an end 65 of the downward portion 64 opens into the side of the connected aerobic tank 2.

[0047] The upward portion 62 has a square cross section of approximately 1 m on each side. The upward portion 62 is provided with a flow rate meter 66 capable of measuring the flow rate of the fluid (denitrified water W3) flowing through the upward portion 62. The measurement value of the flow rate meter 66 is converted into an electric signal and input to the control device 20. In this embodiment, the flow rate meter 66 is provided in all four multi-layer treatment tanks 1 (1A, 1B, 1C, 1D). This allows the flow rate of the denitrified water W3 in each multi-layer treatment tank 1 to be measured independently.

[0048] The protruding part 63 protrudes above the upper end of the aerobic tank 2, and its upper surface is closed by a face piece 67. An opening 68 is provided in the face piece 67, and an exhaust gas passage 9 (an example of a third communication passage) is connected to the opening 68. Since the protruding part 63 protrudes above the upper end of the aerobic tank 2, a liquid level is generated inside the protruding part 63 at approximately the same height as the liquid level in the aerobic tank 2, and a gas phase is formed above that. As a result, in the protruding part 63, the gas generated in the anoxic tank 3 is separated from the denitrified water W3.

[0049] The exhaust gas passage 9 is connected to a deodorizing device (not shown), and a flow meter 91 capable of measuring the flow rate (amount of outflow gas) of gas flowing through the exhaust gas passage 9 is provided midway. The measurement value of the flow meter 91 is converted into an electric signal and input to the control device 20. In this embodiment, the exhaust gas passage 9 and the flow meter 91 are provided in all four multi-layer treatment tanks 1 (1A, 1B, 1C, 1D). This allows the amount of outflow gas in each multi-layer treatment tank 1 to be measured independently.

[0050] Further, a defoaming nozzle 69 (an example of a nozzle) is provided on the protruding portion 63. By spraying water from the defoaming nozzle 69 toward the liquid surface of the denitrified water W3, accumulation of scum on the protruding portion 63 can be suitably prevented.

[0051] The downward portion 64 has a rectangular cross section with a long side of about 3 m and a short side of about 1 m, and the cross-sectional area of ​​the downward portion 64 is larger than that of the upward portion 62. As a result, the flow rate of the denitrified water W3 in the downward portion 64 is smaller than that of the denitrified water W3 in the upward portion 62. By configuring the flow rate of the denitrified water W3 in the downward portion 64 to be relatively small in this manner, the gas to be separated in the protruding portion 63 is less likely to be caught in the flow of the denitrified water W3, and the gas can be easily separated. Specifically, when the agitator 5 (motor 51) is operating, the flow rate of the denitrified water W3 (fluid) in the downward portion 64 is preferably 0.8 m per second or less, more preferably 0.5 m per second or less. Such a flow rate is achieved by appropriately setting the output of the agitator 5 (motor 51) and the cross-sectional area of ​​the downward portion 64.

[0052] [Control of multi-layer treatment tank] Next, a method for controlling the multi-layer treatment tank 1 will be described. The multi-layer treatment tank 1 is provided with a control device 20. The control device 20 receives a measurement value of a flow rate meter 66 (flow rate of the fluid flowing through the upward portion 62 of the denitrification water flow path 6) and a measurement value of a flow rate meter 91 (flow rate of the gas flowing through the exhaust gas passage 9). The control device 20 is also configured to be able to output a control signal to the agitator 5 (motor 51), and the output of the motor 51 is controlled by the control signal. That is, the control device 20 is capable of executing a control function for controlling the agitator 5.

[0053] In addition, various measurement values ​​are also input to the control device 20, such as the raw water inflow amount, which is the flow rate of raw water W1 flowing into the anoxic tank 3, raw water measurement values, which are measurements related to the water quality of the raw water W1 (e.g., pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), nitrogen content, etc.), treated water outflow amount, which is the flow rate of treated water W2 flowing out from the aerobic tank 2, treated water measurement values, which are measurements related to the quality of the treated water flowing out from the aerobic tank 2 (e.g., pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), nitrogen content, etc.), anoxic tank water temperature, which is the water temperature of the anoxic tank 3, and aerobic tank water temperature, which is the water temperature of the aerobic tank 2. These measurement values ​​may be directly input using a measuring device (not shown) installed in the multi-layer treatment tank 1, or the test results performed on samples collected from the multi-layer treatment tank 1 may be input manually.

[0054] In particular, the measurement value (outflow gas volume) of the flow meter 91 is an important index that clearly indicates the status of the denitrification treatment in the anoxic tank 3. In this embodiment, the flow meter 91 can be used to constantly monitor the outflow gas volume, so that the status of the denitrification treatment can be constantly monitored. Then, the operation of the agitator 5 (motor 51) can be controlled according to the status of the denitrification treatment, thereby controlling the operating state of the entire multi-layer treatment tank 1.

[0055] In the multi-layer treatment tank 1 according to this embodiment, the only component provided as a power element is the motor 51, which supplies energy for circulating the water to be treated in the multi-layer treatment tank 1 (sewage treatment system 100) and energy for uniformly stirring the sludge in the anoxic tank 3. If the motor 51 is operated continuously at an output optimized for circulating the water to be treated, the agitation in the anoxic tank 3 may become excessive, resulting in insufficient denitrification treatment. On the other hand, if the motor 51 is operated continuously at an output optimized for agitation in the anoxic tank 3, the circulation of the water to be treated may become insufficient.

[0056] Therefore, in this embodiment, the control function of the control device 20 is configured to be able to set the operation mode of the agitator 5 (motor 51) to a first operation mode in which the motor 51 is operated with an output (first output) optimized for circulation of the water to be treated, or a second operation mode in which the motor 51 is operated with an output (second output) optimized for agitation in the anoxic tank 3. Here, the second output is smaller than the first output. Then, by alternately executing the first operation mode and the second operation mode, both the circulation of the water to be treated and the agitation in the anoxic tank 3 can be performed at an appropriate level.

[0057] The control device 20 is configured to execute an acquisition process for acquiring a data set of at least one parameter at a certain time and a measurement value (outflow gas volume) of the flow rate meter 91 at the time, a data group construction process for accumulating data sets for a plurality of times to construct a data group, and a learning process for constructing a classifier capable of outputting a predicted value of the outflow gas volume predicted based on at least one parameter based on the data group constructed in the data group construction process when the parameter is input. The "parameter" here is selected from the above-mentioned measurement values ​​as parameters that can be input to the control device 20, and is, for example, the measurement value of the flow rate meter 66 (the flow rate of the fluid flowing through the upward portion 62 of the denitrification water flow passage 6), the raw water inflow volume which is the flow rate of the raw water W1 flowing into the anoxic tank 3, and the treated water outflow volume which is the flow rate of the treated water W2 flowing out from the aerobic tank 2.

[0058] By constructing a classifier through the acquisition process, data set construction process, and learning process, it becomes possible to predict the outflow gas volume based on various measured values ​​such as the measured value of the flow meter 66. This makes it possible to predict changes in the operating state of the multi-layer treatment tank 1, so that measures can be taken early to prevent the occurrence of undesirable changes.

[0059] [Control of wastewater treatment systems] A method for controlling the wastewater treatment system 100 will be further described based on the above-mentioned method for controlling the multi-layer treatment tank 1. In controlling the wastewater treatment system 100, it is required to control each of the four multi-layer treatment tanks 1 (1A, 1B, 1C, 1D) so that the operating conditions of the tanks are uniform. In this embodiment, a control method for uniformly controlling the four multi-layer treatment tanks 1 is adopted.

[0060] First, as described above, in this embodiment, the flow rate of the denitrified water W3 and the amount of outflow gas can be measured independently for all four multi-layer treatment tanks 1. This makes it possible to independently grasp the state of each multi-layer treatment tank 1. Simply put, if the amount of outflow gas from each multi-layer treatment tank 1 is uniform, it can be said that the four multi-layer treatment tanks 1 are operating uniformly.

[0061] Conversely, if the amount of gas flowing out of each multi-layer treatment tank 1 is uneven, it is possible that the operating conditions of the four multi-layer treatment tanks 1 are uneven. Specifically, it is assumed that a malfunction has occurred in one of the multi-layer treatment tanks 1. In such a case, measures such as performing maintenance on each multi-layer treatment tank 1 are taken. Specifically, the cause of the abnormality is inferred by checking the uniformity of the inflow of the raw water W1, the uniformity of the amount of dissolved oxygen (DO) in each aerobic tank 2, the uniformity of the current values ​​of each agitator 5 (motor 51), and the uniformity of the flow speeds measured by the flow meter 66.

[0062] In addition, from the viewpoint of operating the four multi-layer treatment tanks 1 evenly, it is preferable that the operation mode of each agitator 5 (motor 51) is changed synchronously. This is because, when some of the agitators 5 are operated in the first operation mode and the other agitators 5 are operated in the second operation mode, the amount of water to be treated from the multi-layer treatment tank 1 to which the agitator 5 operated in the first operation mode belongs becomes larger than the amount of water to be treated from the multi-layer treatment tank 1 to which the agitator 5 operated in the second operation mode belongs, resulting in a difference in the amount of water to be treated in each multi-layer treatment tank 1. In other words, it is preferable to set the same operation mode for all the agitators 5. More specifically, it is preferable to set the same operation mode for all the agitators 5 at the same time.

[0063] As a configuration of the control device for carrying out the above control, a configuration may be adopted in which an overall control device 110 configured to be capable of communicating with the control devices 20 of each multi-layer treatment tank 1 is provided, and the overall control device 110 controls all four control devices 20 (Figure 4), or instead of providing a control device 20 in each multi-layer treatment tank 1, a configuration may be adopted in which one control device 120 controls all four multi-layer treatment tanks 1 collectively (Figure 5).

[0064] [Modification of the first communication passage] In the above embodiment, a configuration has been described as an example in which the draft tube 4 is provided as the first communication passage provided between the aerobic tank 2 and the anoxic tank 3. However, the first communication passage in the present invention is not limited to the above configuration.

[0065] (First Modification) In a first modified example of the first communication passage (FIG. 6), the first communication passage is implemented in the form of a through hole 4a provided between the bottom surface 22 of the aerobic tank 2 and the top surface 31 of the anoxic tank 3. In this case, if the wall surface 4b defining the first communication passage is provided in a manner that protrudes from the top surface 31 of the anoxic tank 3 into the inside of the anoxic tank 3, the same effect as in the embodiment in which the lower end 42 of the draft tube 4 protrudes toward the anoxic tank 3 (FIG. 2) can be obtained. The wall surface 4b may be provided along the edge of the through hole 4a, or may be provided at a position away from the edge of the through hole 4a. However, if the edge of the through hole 4a is too far away from the wall surface 4b, there is a high possibility that gas will flow back from the through hole 4a. Therefore, even if the edge of the through hole 4a is provided away from the wall surface 4b, it should be within the limit that can be technically understood that the wall surface 4b defines the first communication passage continuing from the through hole 4a.

[0066] (Second modified example) In a second modified example of the first communication passage (FIG. 7), a draft tube 4c (an example of a tubular portion) and a sheath pipe portion 4d surrounding the draft tube 4c are provided. A lower end 42a (one end) of the draft tube 4c opens into the anoxic tank 3, and an upper end 41a (the other end) is disposed above the standard liquid level. A communication hole 43 that communicates between the inside of the draft tube 4c and the inside of the sheath pipe portion 4d is provided at a position close to the standard liquid level of the draft tube 4c. A lower end 44 (one end) of the sheath pipe portion 4d opens near the bottom surface 22 of the aerobic tank 2, and an upper end 45 (the other end) is disposed above the standard liquid level. The communication hole 43 is preferably provided at a height from the bottom surface 22 of the aerobic tank 2 that is higher than two-thirds of the standard liquid level, and more preferably at a height higher than four-fifths of the standard liquid level. In addition, the lower end 44 of the sheath pipe portion 4d preferably opens at a position from the bottom surface 22 of the aerobic tank 2 that is lower than two-thirds of the standard liquid level, more preferably opens at a position lower than half the standard liquid level, and even more preferably opens at a position lower than one-third of the standard liquid level.

[0067] In the second modified example, when the agitator 5 is operated, the liquid in the aerobic tank 2 enters the sheath pipe portion 4d from the lower end 44 of the sheath pipe portion 4d, passes through the communication hole 43 and the draft tube 4c in this order, and flows into the anoxic tank 3. In the anoxic tank 3, the amount of dissolved oxygen (DO) needs to be kept below a certain level in order to maintain the activity of the denitrifying bacteria. However, since the amount of dissolved oxygen in the aerobic tank 2 varies depending on the depth from the water surface, it is preferable to supply the nitrifying liquid W4 collected from a location where the amount of dissolved oxygen is relatively low to the anoxic tank 3. In the second modified example, the nitrifying liquid W4 collected from near the bottom of the aerobic tank 2, where the amount of dissolved oxygen is relatively low, is supplied to the anoxic tank 3, so that an increase in the amount of dissolved oxygen in the anoxic tank 3 can be prevented.

[0068] (Third Modification) In the third modified example of the first communication passage (FIG. 8), a draft tube 4e (an example of a tubular portion) and a sheath pipe portion 4d surrounding the draft tube 4c are provided. The configuration of the sheath pipe portion 4d is the same as that of the second modified example (FIG. 7), and is indicated by the same reference numeral. The third modified example differs from the second modified example in that an upper end 41b (the other end) of the draft tube 4e is disposed below the standard liquid level. In addition, while the second modified example has a communication hole 43 that communicates between the inside of the draft tube 4c and the inside of the sheath pipe portion 4d, in the third modified example, the inside of the draft tube 4e communicates with the inside of the sheath pipe portion 4d at the upper end 41b of the draft tube 4e.

[0069] (Fourth Modification) In a fourth modified example of the first communication passage (FIG. 9), a draft tube 4f (an example of a tubular portion) and a suction pipe 4g extending from the side surface of the draft tube 4f and communicating with the inside of the draft tube 4f are provided. A lower end 42c (one end) of the draft tube 4f opens into the anoxic tank 3, and an upper end 41c (the other end) is disposed above the standard liquid level. The suction pipe 4g has a base end 46 connected to the draft tube 4f at a position close to the standard liquid level, and a terminal end 47 opening near the bottom surface 22 of the aerobic tank 2. The base end 46 of the suction pipe 4g is preferably provided at a height from the bottom surface 22 of the aerobic tank 2 higher than two-thirds of the standard liquid level, and more preferably higher than four-fifths of the standard liquid level. In addition, it is preferable that the end 47 of the suction pipe 4g opens at a position from the bottom surface 22 of the aerobic tank 2 that is lower than two-thirds of the standard liquid level, more preferably at a position lower than half the standard liquid level, and even more preferably at a position lower than one-third of the standard liquid level.

[0070] The suction tube 4g may be a tubular member having a fixed shape, or may be a deformable tubular member (a so-called flexible tube). The number of the suction tubes 4g may be one or more.

[0071] Other embodiments Finally, other embodiments of the multi-layer treatment tank and wastewater treatment system according to the present invention will be described. Note that the configurations disclosed in each of the following embodiments can be combined with the configurations disclosed in other embodiments as long as no contradiction occurs.

[0072] In the above embodiment, a configuration in which a plurality of membrane separation devices 21 are provided in the aerobic tank 2 has been described as an example. However, the aerobic tank in the present invention is not limited to a configuration in which a membrane separation device is used, and an aerobic tank of a type known in the art may be used.

[0073] In the above embodiment, a wastewater treatment system 100 equipped with four multi-layer treatment tanks 1 (1A, 1B, 1C, 1D) has been described as an example. However, the number of multi-layer treatment tanks 1 installed in the wastewater treatment system according to the present invention is not limited, and may be one or more. An example in which one multi-layer treatment tank is used alone is shown in FIG. 10. In this example, an end 65 of the denitrification water flow path 6 opens into an aerobic tank 2 belonging to the same multi-layer treatment tank 1, and a circulation system that is completed within the single multi-layer treatment tank 1 is formed.

[0074] In the above embodiment, an example has been described in which the multi-layer treatment tank 1 includes an aerobic tank 2 and an anoxic tank 3, and is used for activated wastewater treatment by a circulating nitrification-denitrification method. However, the wastewater treatment method to which the multi-layer treatment tank 1 is applied is not particularly limited. When the multi-layer treatment tank 1 is applied to another wastewater treatment method, other tanks (e.g., anaerobic tanks) required for that wastewater treatment method may be provided integrally with or separately from the multi-layer treatment tank according to the present invention.

[0075] In the above embodiment, an example has been described in which a plurality of membrane separation devices 21 are provided in the aerobic tank 2, and the multi-layer treatment tank 1 is used for a membrane bioreactor (MBR) process. However, the sewage treatment system to which the multi-layer treatment tank of the present invention is applied is not particularly limited. When the multi-layer treatment tank of the present invention is applied to another sewage treatment system, devices and equipment required for that sewage treatment system may be provided integrally with or separately from the multi-layer treatment tank of the present invention.

[0076] In the above embodiment, the aerobic tank 2 is provided with an agitator 5 having a motor 51, an impeller 52, and a shaft member 53. However, in the multi-layer treatment tank according to the present invention, the configuration and installation position of the biasing device are not limited as long as the biasing device is arranged so that a flow is formed from the aerobic tank through the first communication passage to the anoxic tank when the biasing device is operated. For example, the agitator may be a submersible pump.

[0077] In the above embodiment, the configuration in which the upper surface 31 of the anoxic tank 3 is inclined has been described as an example. However, the upper surface of the anoxic tank according to the present invention may be horizontal.

[0078] In the above embodiment, the pit 7 and the aeration pipe 8 are provided in the anoxic tank 3, and the gas generated in the anoxic tank 3 flows into the denitrification water flow path 6 via the pit 7 and the aeration pipe 8. However, the multi-layer treatment tank according to the present invention may be configured so that the gas generated in the anoxic tank 3 directly flows into the denitrification water flow path 6. In addition, in the above embodiment, the aeration pipe 8 is connected to the water supply source, but when the aeration pipe is provided, it does not necessarily have to be connected to the water supply source.

[0079] In the above embodiment, the denitrification water flow path 6 has a protruding portion 63. However, in the multi-layer treatment tank according to the present invention, the denitrification water flow path may have a structure that does not have a protruding portion. In addition, when a protruding portion is provided in the denitrification water flow path, the upper surface of the protruding portion may be left open.

[0080] In the above embodiment, a configuration has been described in which the flow meter 66 is provided in the upward portion 62 of the denitrification water flow path 6, and the flow meter 91 is provided in the exhaust gas path 9. However, in the multi-layer treatment tank according to the present invention, these flow meters are not essential, and therefore either one or both of them may be omitted.

[0081] In the above embodiment, an example has been described in which the defoaming nozzle 69 is provided on the protruding portion 63 of the denitrification water flow path 6. However, the multi-layer treatment tank according to the present invention does not necessarily have to have a defoaming nozzle.

[0082] In the above embodiment, the measurement values ​​of the flow meter 66 and the flow meter 91 are input to the control device 20, and the control device 20 is configured to be able to output a control signal to the agitator 5 (motor 51). However, in the multi-layer treatment tank according to the present invention, the configuration of the control device and the control method are arbitrary, and a control device having a configuration compatible with the selected control method may be adopted. In addition, the connection between the control device and other components, the specifications of the various measuring instruments, and the installation locations may also be appropriately selected to be compatible with the selected control method.

[0083] Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereto. A person skilled in the art would easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention. [Industrial Applicability]

[0084] The present invention can be used, for example, in a treatment tank and a wastewater treatment system for activated wastewater treatment by a circulating nitrification-denitrification method. [Explanation of symbols]

[0085] 1: Multi-layer treatment tank 2:Aerobic tank 21: Membrane separation device 22: Bottom of aerobic tank 3: Anoxic tank 31: Top of the anoxic tank 4: Draft tube 41: Top of draft tube 42: Bottom end of draft tube 5: Mixer 51: Motor 52: Impeller 53: Shaft member 6: Denitrification water flow path 61: Lower end of denitrification water flow path 62:Upward part 63:Protruding part 64:Downward part 65: End of denitrification water flow path 66: Velocity meter 67: Facet 68: Opening 69: Defoaming nozzle 7: Pit 8: Diffuser pipe 81: Pore 9:Third passageway 91: Velocity meter 20: Control device 100: Sewage treatment system 110: General control device 120: Control device W1: Raw water W2: Treated water W3: Denitrified water W4: Nitrification liquid H: Dashed line representing standard liquid level (First Modification) 4a: Through hole 4b: Wall (Second modified example) 4c: Draft tube 4d: Sheath tube part 41a: Top of draft tube 42a: Lower end of draft tube 43:Communication hole 44: Lower end of the sheath tube 45: Upper end of the sheath tube (Third Modification) 4e: Draft tube 41b: Top of draft tube 42b: Lower end of draft tube (Fourth Modification) 4f: Draft tube 4g:Suction tube 41c: Top of draft tube 42c: Lower end of draft tube 46: Base end of suction tube 47: End of suction tube

Claims

1. A multi-layer treatment tank having an aerobic tank in an upper layer and an anoxic tank in a lower layer, a first communication passage provided between the aerobic tank and the anoxic tank; A second communication passage provided between the anoxic tank and a tank other than the anoxic tank; and a biasing device capable of biasing the fluid; the first communication passage and the biasing device are arranged such that, when the biasing device is operated, a flow is formed that flows from the aerobic tank through the first communication passage into the anoxic tank, One end of the second communication passage is open to an upper surface of the anoxic tank, a wall surface defining the first communication passage at one end thereof protrudes from an upper surface of the anoxic tank into the anoxic tank; The second communication passage has a protruding portion protruding above an upper edge of the aerobic tank, The upper surface of the protruding portion is closed by a face piece having an opening, A third communication passage is connected to the opening, The third communication passage is provided with a flow rate meter capable of measuring the flow rate of gas flowing through the third communication passage.

2. The upper surface of the anoxic tank is inclined, 2. The multi-layer treatment tank according to claim 1, wherein one end of said second communication passage is provided at an upper end portion of said inclined upper surface.

3. The first communication passage has a tubular portion extending into the aerobic tank, A standard liquid level, which is a liquid level under normal operating conditions, is set in the aerobic tank, the biasing device has a power unit provided above the standard liquid level, and a biasing unit provided below the standard liquid level and driven by the power of the power unit to bias the fluid, 3. The multi-layer treatment tank according to claim 1, wherein the biasing portion is housed in the tubular portion.

4. a pit surrounding a portion of the upper surface of the anoxic tank where one end of the second communication passage is open; The multi-layer treatment tank according to any one of claims 1 to 3, further comprising an aeration pipe connected to the pit.

5. 5. The multi-layer treatment tank according to claim 4, wherein said aeration pipe is further connected to a water supply source.

6. 6. The multi-layer treatment tank according to claim 1, wherein a nozzle capable of spraying water is provided on the inside of the protruding portion.

7. at least one parameter selected from the group consisting of a raw water inflow rate, which is the flow rate of raw water flowing into the anoxic tank; a raw water measurement value, which is a measurement value relating to the water quality of the raw water; a treated water outflow rate, which is the flow rate of treated water flowing out of the aerobic tank; a treated water measurement value, which is a measurement value relating to the quality of the treated water flowing out of the aerobic tank; an anoxic tank water temperature, which is the water temperature of the anoxic tank; an aerobic tank water temperature, which is the water temperature of the aerobic tank; and a flow velocity of a fluid flowing through the second communication passage; The flow rate of the gas discharged from the flow meter is measured by a control device. The control device includes: an acquisition process for acquiring a data set of the at least one parameter at a certain time and the outflow gas amount at the time; A data group construction process for accumulating the data sets for a plurality of times to construct a data group; and A multi-layer treatment tank as described in any one of claims 1 to 6, which is configured to execute a learning process to construct a classifier based on the group of data, which can output a predicted value of the outflow gas volume based on at least one parameter when the at least one parameter is input.

8. A wastewater treatment system comprising a plurality of multi-layer treatment tanks, each having an aerobic tank in an upper layer, an anoxic tank in a lower layer, a first communication passage extending between the aerobic tank and the anoxic tank, and a biasing device capable of biasing a fluid, wherein the plurality of multi-layer treatment tanks form a circulatory system in which the aerobic tanks and the anoxic tanks are alternately connected, the first communication passage and the biasing device are arranged such that, when the biasing device is operated, a flow is formed that flows from the aerobic tank through the first communication passage into the anoxic tank, a wall surface defining the first communication passage at one end thereof protrudes from an upper surface of the anoxic tank into the anoxic tank; Two adjacent multi-layer treatment tanks in the circulation system are connected by a second communication passage provided between the anoxic tank of one of the multi-layer treatment tanks and the aerobic tank of the other of the multi-layer treatment tanks; One end of the second communication passage is open to an upper surface of the anoxic tank, each of the second communication passages has a protruding portion protruding above an upper edge of the aerobic tank of each of the two multi-layer treatment tanks connected by the second communication passage; The upper surface of the protruding portion is closed by a face piece having an opening, A third communication passage is connected to the opening, A wastewater treatment system, wherein each of the third communication passages is provided with a flow meter capable of measuring a flow velocity of gas flowing through the third communication passage.

9. The second communication passage has a downward portion extending downward from the protruding portion to the other end opening into the aerobic tank, 9. The wastewater treatment system according to claim 8, wherein the flow velocity of the fluid in the downward portion is set to 0.8 meters per second or less when the biasing device is in operation.

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