Wastewater treatment method

Abstract

To provide a wastewater treatment method capable of stably conducting wastewater treatment.SOLUTION: A wastewater treatment method flows wastewater into a regulation tank and discharges out of the regulation tank to a wastewater treatment facility. The wastewater treatment method is configured to: measure a water quality item or an operation control item related to a wastewater load continuously or periodically; estimate a wastewater load of a wastewater inflow part (wastewater treatment inflow part) to the wastewater treatment facility with an operation expression preset according to a measured value; and if the estimated wastewater load is lower than a prescribed threshold value, supply the wastewater to the regulation tank, and if the estimated wastewater load is at the threshold value or higher, bifurcate the wastewater at a wastewater bifurcation position upstream of the regulation tank and reserve the wastewater in a high load regulation tank.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wastewater treatment method that estimates the wastewater load at the inlet of a wastewater treatment plant, allocates high-load wastewater to a separate tank based on the estimated wastewater load to prevent the wastewater treatment from failing, and delivers the high-load wastewater at a timing when the wastewater load is low, thereby stabilizing the wastewater treatment. [Background technology]

[0002] Wastewater discharged from beverage, food, and other manufacturing plants often varies greatly in concentration and volume depending on the product and production volume, the elapsed time for cleaning the production line, etc. The optimal operating conditions for wastewater treatment often differ depending on the wastewater load, and large fluctuations in the wastewater load can affect the treatment status.

[0003] In particular, organic wastewater is generally treated by biological treatment such as aerobic or anaerobic treatment. However, if the wastewater load is large, the biological treatment may fail due to the organisms exceeding their processing capacity, resulting in problems such as a deterioration in the quality of the treated water.

[0004] In addition, in physicochemical processes such as the Fenton reaction and adsorption, the amount of chemicals or adsorbents required to be added changes, so it is important to understand the fluctuations in the load of wastewater flowing into the treatment facility.

[0005] Conventionally, operators would periodically collect and analyze wastewater to grasp the wastewater load at the inflow point of the wastewater treatment plant, and when high-load wastewater flowed in, they would manually take measures such as emergency evacuation to another tank, dilution, and reducing the amount of inflow to the wastewater treatment plant. However, this method does not allow continuous measurement because it is always done manually, and if the inflow of high-load wastewater is overlooked or measures are delayed, the wastewater treatment plant may break down and the quality of the treated water may deteriorate. Therefore, it is very important to continuously grasp the load of inflowing wastewater and take measures as soon as possible to prevent the wastewater treatment plant from breaking down.

[0006] Patent Document 1 discloses a wastewater treatment device that stabilizes wastewater treatment by dividing the treatment process according to the concentration. Specifically, wastewater is divided into high-concentration wastewater and low-concentration wastewater based on the measured electrical conductivity of the wastewater. However, it is difficult to fully evaluate pollutants with low electrical conductivity with the electrical conductivity measured by this method. In addition, high-concentration wastewater and low-concentration wastewater are distinguished as high or low concentration by comparing the two, and are not limited by numerical values. In such a method, the judgment of whether the wastewater is high or low concentration varies depending on the water quality of the wastewater. For example, if high-concentration wastewater continues for a long time, there is a concern that wastewater with a concentration that affects the subsequent wastewater treatment will be classified as low-concentration wastewater. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2002-282889 A Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a wastewater treatment method capable of stably performing wastewater treatment. [Means for solving the problem]

[0009] [1] A wastewater treatment method in which wastewater flows into an adjustment tank and is then sent from the adjustment tank to a wastewater treatment facility, Water quality items or operational management items related to wastewater load are continuously or periodically measured, and the wastewater load at the wastewater inlet (wastewater treatment inlet) to the wastewater treatment facility is estimated using a preset calculation formula based on the measured values; If the estimated wastewater load is less than a predetermined threshold, the wastewater is supplied to the adjustment tank; When the estimated wastewater load is equal to or greater than the threshold value, the wastewater is branched at a wastewater branch position upstream of the adjustment tank and stored in a high-load adjustment tank.

[0010] [2] The wastewater treatment method according to [1], wherein the water quality items or operational management items related to the wastewater load include the pollution load of the wastewater or items correlated with the pollution load, and the wastewater flow rate flowing into the wastewater treatment facility.

[0011] [3] A wastewater treatment method according to [1] or [2], in which if the wastewater load when water is pumped from the high-load adjustment tank and joined downstream of the wastewater branching position becomes equal to or less than a predetermined threshold value, water is pumped from the high-load adjustment tank.

[0012] [4] The wastewater treatment method according to [3], wherein water is conveyed from the high-load adjustment tank to join the downstream side of the adjustment tank.

[0013] [5] The wastewater treatment method according to [3], wherein water is pumped from the high-load adjustment tank to the adjustment tank. Effect of the Invention

[0014] According to the present invention, wastewater treatment can be carried out stably. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Diagram 2] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Diagram 3] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Figure 4] 1 is a schematic configuration diagram of a wastewater treatment system according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic configuration diagram of a wastewater treatment system according to the embodiment. [Figure 6] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Figure 7] 1 is a schematic configuration diagram of a wastewater treatment system according to an embodiment of the present invention. [Figure 8] FIG. 2 is a schematic configuration diagram of a wastewater treatment system according to the embodiment. [Figure 9]FIG. 2 is a schematic configuration diagram of a wastewater treatment system according to the embodiment. [Figure 10] FIG. 2 is a schematic configuration diagram of a wastewater treatment system according to the embodiment. [Figure 11] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Figure 12] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Figure 13] 1 is a schematic configuration diagram of a wastewater treatment system according to an embodiment of the present invention. [Figure 14] FIG. 2 is a schematic configuration diagram of a wastewater treatment system according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The wastewater treatment system according to an embodiment of the present invention receives wastewater in an adjustment tank and sends the wastewater from the adjustment tank to a wastewater treatment facility, and measures the pollution load upstream of the adjustment tank, the flow rate of wastewater flowing into the adjustment tank, and the flow rate of wastewater flowing into the wastewater treatment facility, and uses these to estimate the wastewater load at the inlet of the wastewater treatment facility (hereinafter also referred to as the "wastewater treatment inlet"). Based on the estimated wastewater load, high-load wastewater is allocated to a separate storage tank so that the wastewater treatment does not break down, and high-load wastewater is sent at a timing when the wastewater load is low, thereby stabilizing the wastewater treatment.

[0017] One or more adjustment tanks are provided, and as described later, a plurality of adjustment tanks 1 may be arranged in parallel or in series. The specifications of the adjustment tank, such as its volume, are not particularly limited. The treatment method and number of systems of the wastewater treatment facility are not particularly limited. Examples of the treatment method include so-called biological treatment, including aerobic and anaerobic treatment, and physicochemical treatment, such as Fenton treatment and activated carbon treatment.

[0018] Next, a method for estimating the wastewater load at the inlet of the wastewater treatment plant will be described with reference to the drawings.

[0019] As shown in Fig. 1, when a wastewater treatment system includes an adjustment tank 1 and a wastewater treatment facility 3 installed after the adjustment tank 1 (downstream side), the pollution load of the wastewater is measured by a pollution load measuring unit 4 installed before the adjustment tank 1 (upstream side). In addition, a first flow rate measuring unit 5 is used to measure the flow rate of the wastewater flowing into the adjustment tank 1, and a second flow rate measuring unit 10 is used to measure the flow rate of the wastewater flowing into the wastewater treatment facility 3.

[0020] The adjustment tank 1 has an HRT (hydraulic retention time) of 30 minutes or more for the purpose of adjusting and mitigating fluctuations in water quality and water volume.

[0021] In this embodiment, an example of measuring TOC concentration as the pollution load will be described, but the measurement item is not limited to TOC concentration, and may be other indicators of pollution load such as COD concentration or SS concentration. In addition, the item measured by the pollution load measuring unit 4 may be an item correlated with the pollution load, such as electrical conductivity or Brix sugar content.

[0022] A flow meter can be used as the first flow rate measuring unit 5. When the adjustment tank 1 is a batch-wise water supply tank, the first flow rate measuring unit 5 may calculate the flow rate of wastewater flowing into the adjustment tank 1 from the increase in water level per unit time in the adjustment tank 1. Alternatively, when the adjustment tank 1 is a continuous water supply tank, the flow rate of wastewater flowing into the adjustment tank 1 may be calculated from the sum of the change in the storage volume of the adjustment tank 1 and the discharge flow rate from the adjustment tank.

[0023] A flow meter can be used as the second flow rate measuring unit 10. When the adjustment tank 1 is a batch water supply type, the second flow rate measuring unit 10 may calculate the flow rate of wastewater flowing into the wastewater treatment facility 3 from the amount of decrease in the water level in the adjustment tank 1 per unit time.

[0024] The pollution load measuring unit 4, the first flow rate measuring unit 5 and the second flow rate measuring unit 10 continuously or periodically measure the pollution load or items correlated therewith, which are water quality items or operational management items related to wastewater load, the flow rate of wastewater flowing into the adjustment tank 1, and the flow rate of wastewater flowing into the wastewater treatment system, either continuously or at relatively short time intervals.

[0025] The calculation unit 6 estimates the TOC concentration at the wastewater treatment inlet (outlet of the adjustment tank 1) using the TOC concentration measured by the pollution load measurement unit 4 and the flow rate measured by the first flow rate measurement unit 5. The calculation unit 6 also estimates the wastewater load (kg-TOC / day) at the wastewater treatment inlet using the estimated TOC concentration and the flow rate measured by the second flow rate measurement unit 10.

[0026] The TOC concentration at the inlet of the wastewater treatment plant can be estimated using the TOC concentration measured by the pollution load measuring unit 4 and the flow rate measured by the first flow rate measuring unit 5 using various proposed concentration calculation models for retention tanks. However, depending on whether the adjustment tank 1 is a continuous or batch flow tank, for example, different estimation methods can be used, as follows:

[0027] <When water is continuously flowing> Estimation method (1)-1 The TOC concentration (mg / L) at the inlet of the wastewater treatment process is estimated by taking a moving average of the TOC concentration measured upstream of the equalization tank 1 over a time period close to the residence time in the equalization tank 1. For example, if the residence time in the equalization tank 1 is 50 minutes, the average of the TOC concentration measurement results from the present to the previous 50 minutes can be regarded as the TOC concentration at the inlet of the wastewater treatment process (discharged from the equalization tank 1).

[0028] Estimation method (2)-1 From the TOC concentration and flow rate measured upstream of equalization tank 1, a perfect mixing tank model is used to estimate the change in wastewater concentration flowing into equalization tank 1, and the TOC concentration (mg / L) at the wastewater treatment inlet is estimated.

[0029] <When passing water through a batch> Estimation method (3)-1 The total TOC weight (g) flowing into the adjustment tank 1 is calculated by dividing the total water volume (m 3) to estimate the TOC concentration (mg / L) at the inlet of the wastewater treatment plant. In order to accurately grasp the total TOC weight and total water volume that have flowed into the equalization tank 1, it is desirable to obtain the equalization tank inlet valve open / close signal and the pump start / stop signal, and calculate the load by integrating the TOC concentration and water volume from the inlet valve "open" to "closed" or the time the pump is operating. If it is difficult to obtain the valve open / close signal or the pump start / stop signal, it is also possible to grasp the timing at which wastewater is flowing into the equalization tank 1 from the change in the water level in the equalization tank 1.

[0030] The calculation unit 6 estimates the wastewater load (kg-TOC / day) using the TOC concentration at the wastewater treatment inlet estimated by any of the above estimation methods (1)-1, (2)-1, or (3)-1 and the flow rate at the wastewater treatment inlet measured by the second flow measurement unit 10, using the following equation 1.

[0031] Equation 1: Wastewater load (kg-TOC / day) = TOC concentration at the inlet of the wastewater treatment plant (mg / L) × flow rate at the inlet of the wastewater treatment plant (m 3 / h)×24h / 1000

[0032] As shown in FIG. 2, when an adjustment tank 2 is provided in series with the adjustment tank 1 between the adjustment tank 1 and the wastewater treatment equipment 3, the TOC concentration (estimated value A) at the outlet of the adjustment tank 1 is estimated first. One or more adjustment tanks 2 are provided, and as described later, a plurality of adjustment tanks 2 may be arranged in parallel. The specifications of the adjustment tank 2, such as its volume, are not particularly limited. As in FIG. 1, the estimation method differs depending on whether the adjustment tank 1 is a continuous water supply or a batch water supply. In the case of continuous water supply, the above estimation method (1)-1 or (2)-1 is used to estimate the TOC concentration (estimated value A) at the outlet of the adjustment tank 1, and in the case of batch water supply, estimation method (3)-1 is used.

[0033] Next, the TOC concentration (estimated value B) at the wastewater treatment inlet (outlet of the adjustment tank 2) is estimated from the TOC concentration (estimated value A) at the outlet of the adjustment tank 1 obtained as described above and the flow rate of the wastewater flowing into the adjustment tank 2 measured by the third flow measurement unit 8. Again, the estimation method differs depending on whether the adjustment tank 2 is a continuous water supply or a batch water supply. In the case of continuous water supply, the following estimation method (1)-2 or (2)-2 is used to estimate the TOC concentration (estimated value B) at the wastewater treatment inlet. In the case of batch water supply, estimation method (3)-2 is used.

[0034] Estimation method (1)-2 The TOC concentration (mg / L) at the inlet of the wastewater treatment plant is estimated by taking a moving average of the TOC concentration (estimated value A) over a period close to the residence time in the adjustment tank 2.

[0035] Estimation method (2)-2 From the TOC concentration (estimated value A) and the flow rate flowing into equalization tank 2, a perfect mixing tank model is used to estimate the change in the wastewater concentration flowing into equalization tank 2, and the TOC concentration (mg / L) at the wastewater treatment inlet is estimated.

[0036] Estimation method (3)-2 The total TOC weight (g) flowing into the adjustment tank 2 is calculated by dividing the total water volume (m 3 ) to estimate the TOC concentration (mg / L) at the wastewater treatment inlet.

[0037] The third flow rate measuring unit 8, which measures the flow rate of the wastewater flowing into the adjustment tank 2, may be a flow meter, or, in the case where the adjustment tank 2 is a batch-flow type, may be a unit that calculates the flow rate from the increase in the water level per unit time in the adjustment tank 2. Alternatively, in the case where the adjustment tank 2 is a continuous flow type, the flow rate of the wastewater flowing into the adjustment tank 2 may be calculated from the sum of the change in the storage volume of the adjustment tank 2 and the discharge flow rate from the adjustment tank.

[0038] The wastewater load (kg-TOC / day) is estimated using the above equation 1 from the TOC concentration (estimated value B) at the wastewater treatment inlet obtained in this manner and the flow rate at the wastewater treatment inlet measured by the second flow measurement unit 10.

[0039] Next, as shown in Fig. 3, let us consider a case in which equalization tanks 2A and 2B are provided in parallel between equalization tank 1 and wastewater treatment equipment 3, and wastewater is returned from equalization tank 2B to equalization tank 1. Wastewater flowing out from equalization tank 1 flows into equalization tank 2A ​​or 2B. Wastewater flowing out from equalization tank 2A ​​flows into wastewater treatment equipment 3. Wastewater flowing out from equalization tank 2B is returned to equalization tank 1.

[0040] The fourth flow rate measuring unit 13 measures the flow rate of wastewater flowing into the adjustment tank 2B, and may be measured by a flow meter or calculated from the amount of increase in the water level per unit time in the adjustment tank 2B. The fifth flow rate measuring unit 15 measures the flow rate of wastewater returned from the adjustment tank 2B to the adjustment tank 1, and may be measured by a flow meter or calculated from the amount of decrease in the water level per unit time in the adjustment tank 2B.

[0041] In this case, the condition is that the adjustment tank 2B, which returns wastewater to the adjustment tank 1, is a batch water supply tank, and the adjustment tank 1 and the adjustment tank 2A ​​may be either continuous water supply tank or batch water supply tank. One or more adjustment tanks 2A are provided, and a plurality of adjustment tanks 2A may be arranged in parallel.

[0042] First, the TOC concentration (estimated value C) of the wastewater in the adjustment tank 2B is estimated using the following estimation method (3)-3 from the TOC concentration measured upstream of the adjustment tank 1 and the flow rate measured by the fourth flow rate measurement unit 13.

[0043] Estimation method (3)-3 The total TOC weight (g) flowing into the adjustment tank 2B is expressed as the total water volume (m 3 ) to estimate the TOC concentration (mg / L) in equalization tank 2B.

[0044] Next, the TOC concentration at the outlet of the adjustment tank 1 (estimated value D) is estimated from the TOC concentration in the adjustment tank 2B obtained as described above (estimated value C), the flow rate measured by the fifth flow rate measurement unit 15, and the TOC concentration and flow rate measured upstream of the adjustment tank 1. When the adjustment tank 1 is a continuous water supply tank, the estimation is performed using estimation method (2)-3, and when the adjustment tank 1 is a batch water supply tank, the estimation is performed using estimation method (3)-4.

[0045] Estimation method (2)-3 From the TOC concentration and flow rate measured upstream of equalization tank 1, the TOC concentration in equalization tank 2B (estimated value C), and the flow rate flowing from equalization tank 2B to equalization tank 1, a perfect mixing tank model is used to estimate the change in wastewater concentration flowing into equalization tank 1, and the TOC concentration (mg / L) at the outlet of equalization tank 1 is estimated.

[0046] Estimation method (3)-4 The total TOC weight (g) flowing into the adjustment tank 1 is multiplied by the total water volume (m 3 ) to estimate the TOC concentration (mg / L) at the outlet of equalization tank 1. The total TOC weight and total water volume are calculated by adding the TOC weight and water volume measured upstream of equalization tank 1 to the TOC weight and water volume returned from equalization tank 2B, respectively.

[0047] Next, the TOC concentration (estimated value E) at the wastewater treatment inlet (outlet of the adjustment tank 2A) is estimated from the TOC concentration (estimated value D) at the outlet of the adjustment tank 1 obtained as described above and the flow rate into the adjustment tank 2A. If the adjustment tank 2A ​​is a continuous water supply system, the TOC concentration (estimated value E) at the wastewater treatment inlet is estimated using estimation method (1)-3 or (2)-4, and if it is a batch water supply system, estimation method (3)-5.

[0048] Estimation method (1)-3 The TOC concentration (estimated value D) is averaged over a period close to the residence time in the equalization tank 2A ​​to estimate the TOC concentration (mg / L) at the inlet of the wastewater treatment plant.

[0049] Estimation method (2)-4 From the TOC concentration (estimated value D) and the flow rate flowing into the equalization tank 2A, a perfect mixing tank model is used to estimate the change in the wastewater concentration flowing into the equalization tank 2A, and the TOC concentration (mg / L) at the wastewater treatment inlet is estimated.

[0050] Estimation method (3)-5 The total TOC weight (g) flowing into the adjustment tank 2A ​​is calculated by dividing the total water volume (m 3 ) to estimate the TOC concentration (mg / L) at the wastewater treatment inlet.

[0051] The wastewater load (kg-TOC / day) is estimated using the above equation 1 from the TOC concentration (estimated value E) at the wastewater treatment inlet obtained in this manner and the flow rate at the wastewater treatment inlet measured by the second flow measurement unit 10.

[0052] According to this embodiment, the pollution load (or items correlated with the pollution load) on the upstream side of the adjustment tank 1, the flow rate of wastewater flowing into the adjustment tank, and the flow rate of wastewater flowing into the wastewater treatment facility are measured, and the wastewater load at the inlet of the wastewater treatment is estimated using these. From this estimated value, the inflow rate to the wastewater treatment can be controlled, or high-load wastewater can be distributed to a high-load adjustment tank (see Figs. 4 to 14), thereby stabilizing the wastewater treatment.

[0053] A threshold is set for the estimated wastewater load, and if the wastewater load is equal to or greater than the threshold, it is distributed to the high-load adjustment tank, and if it is less than the threshold, it is distributed to the normal adjustment tank. The threshold is set under conditions that will not cause the wastewater treatment to fail, such as being equal to or less than the design standard value of the downstream wastewater treatment equipment. In addition to the current wastewater load, the wastewater load of wastewater that passed through several hours ago may be added to the threshold judgment. For example, if the current wastewater load is equal to or greater than the set threshold A and the wastewater load from several hours ago was equal to or greater than the set threshold B, it may be distributed to the high-load adjustment tank. It is desirable to set the threshold in advance according to the situation on site.

[0054] When water is sent from the high-load adjustment tank to mix with wastewater, if the wastewater load at the wastewater treatment inlet is less than a set threshold when the wastewater load sent from the high-load adjustment tank is added, water is sent from the high-load adjustment tank. Conversely, if the added load is equal to or greater than the threshold, water is not sent and is stored in the high-load adjustment tank.

[0055] Specific examples of the method of allocating water to the high-load adjustment tank and the method of sending water from the high-load adjustment tank will be described below.

[0056] Fig. 4 shows a configuration in which a high-load adjustment tank 12 is provided in the wastewater treatment system shown in Fig. 1. In the configuration shown in Fig. 4, the high-load adjustment tank 12 is arranged in parallel with the adjustment tank 1. Wastewater delivered by a transfer pump 11 branches upstream of the adjustment tank 1, and by controlling the opening and closing of valves 17A and 17B, it is possible to switch whether the wastewater flows into the adjustment tank 1 or the high-load adjustment tank 12.

[0057] The calculation unit 6 acquires the TOC concentration measured by the pollution load measurement unit 4 and the flow rate measured by the first flow rate measurement unit 5, and estimates the TOC concentration at the inlet of the wastewater treatment by any one of the above estimation methods (1)-1, (2)-1, or (3)-1. The calculation unit 6 also estimates the wastewater load at the inlet of the wastewater treatment using the estimated TOC concentration and the flow rate measured by the second flow rate measurement unit 10, and determines whether it is acceptable for the wastewater to flow into the wastewater treatment facility 3.

[0058] Under normal circumstances, wastewater flows into the adjustment tank 1. When the calculation unit 6 determines that the estimated wastewater load is equal to or greater than a predetermined threshold and that the wastewater treatment may fail, it closes valve 17A and opens valve 17B to distribute the wastewater to the high-load adjustment tank 12. Even after the wastewater inflow destination is switched to the high-load adjustment tank 12, the transfer pump 20 continues to transport the wastewater from the adjustment tank 1 to the wastewater treatment equipment 3, and the calculation unit 6 continues to estimate the TOC concentration at the wastewater treatment inflow and the wastewater load.

[0059] Thereafter, when the estimated wastewater load falls below the threshold, the wastewater inflow destination is switched from the high-load adjustment tank 12 to the adjustment tank 1. The calculation unit 6 also controls the transfer pump 19 to adjust the timing of sending high-load wastewater from the high-load adjustment tank 12 to the wastewater treatment equipment 3 so as not to cause the wastewater treatment to fail. When the wastewater load when the wastewater from the high-load adjustment tank 12 is mixed (merged) with the wastewater from the adjustment tank 1 downstream of the adjustment tank 1 falls below a predetermined threshold, the calculation unit 6 sends water from the high-load adjustment tank 12. When the wastewater load after mixing is equal to or greater than the threshold, the water is not sent from the high-load adjustment tank 12 and is left stored.

[0060] The calculation unit 6 may display the timing of opening and closing the valves 17A and 17B on a monitor screen or the like, and an operator may manually control the opening and closing of the valves 17A and 17B according to the display. Similarly, the calculation unit 6 may display the timing of water supply from the transfer pumps 19 and 20 on a monitor screen or the like so that the operator can understand, and the operator may manually operate the pumps according to the display. Also, a transfer pump may be installed downstream of the junction instead of the transfer pumps 19 and 20, and a switching valve may be provided just before the junction where the wastewater from the adjustment tank 1 and the high-load adjustment tank is junction, allowing operation with a single transfer pump.

[0061] In the configuration shown in Figure 4, a configuration has been described in which the wastewater in the high-load adjustment tank 12 is sent to the wastewater treatment equipment 3, but as shown in Figure 5, the wastewater in the high-load adjustment tank 12 may also be sent to the adjustment tank 1.

[0062] In the configuration shown in FIG. 6, wastewater is arbitrarily sent to the adjustment tank 1 and the adjustment tank 1' without considering the pollution load of the wastewater. When sending wastewater to the adjustment tank 2, the valve 7A is opened and the valve 7B is closed, and when sending wastewater to the adjustment tank 2', the valve 7A is closed and the valve 7B is opened. In addition, of the adjustment tanks 2 and 2', the adjustment tank to which wastewater is not sent sends wastewater to the wastewater treatment equipment 3. When the calculation unit 6 judges that the wastewater load is high and the wastewater treatment may fail, it controls the transfer pumps 19' and 20' to adjust the flow rate of the wastewater sent from the adjustment tank 1 and the adjustment tank 1' so that the wastewater load (TOC concentration x flow rate) does not fail the wastewater treatment. The calculation unit 6 displays the water supply amount of the transfer pumps 19' and 20' on a monitor screen so that the amount can be known, and an operator may manually operate the pump according to the display. In addition, instead of the transfer pumps 19' and 20', a transfer pump may be installed downstream of the confluence, and a switching valve may be provided just before the confluence of the wastewater from the adjustment tank 1 and the high-load adjustment tank 12, making it possible to operate the system with a single transfer pump.

[0063] Fig. 7 shows a configuration in which a high-load adjustment tank 12 is provided in parallel with the adjustment tank 2 of the wastewater treatment system shown in Fig. 2. By controlling the opening and closing of valves 7A and 7B, it is possible to switch whether wastewater conveyed from the adjustment tank 1 flows into the adjustment tank 2 or the high-load adjustment tank 12.

[0064] The calculation unit 6 acquires the TOC concentration measured by the pollution load measurement unit 4 and the flow rate measured by the first flow rate measurement unit 5, and estimates the TOC concentration at the outlet of the adjustment tank 1 by any one of the above estimation methods (1)-1, (2)-1, or (3)-1.

[0065] The calculation unit 6 estimates the TOC concentration at the wastewater treatment inlet by any one of the above estimation methods (1)-2, (2)-2, or (3)-2 using the estimated TOC concentration at the outlet of the adjustment tank 1 and the flow rate of the wastewater flowing into the adjustment tank 2 measured by the third flow rate measurement unit 8. The calculation unit 6 also estimates the wastewater load at the wastewater treatment inlet by the above formula 1 from the estimated TOC concentration at the wastewater treatment inlet and the flow rate of the wastewater treatment inlet measured by the second flow rate measurement unit 10.

[0066] Under normal circumstances, wastewater from the adjustment tank 1 flows into the adjustment tank 2. When the calculation unit 6 determines that the estimated wastewater load is equal to or greater than a predetermined threshold and that the wastewater treatment may fail, it closes valve 7A and opens valve 7B to allow the wastewater sent from the adjustment tank 1 to flow into the high-load adjustment tank 12. Even after the wastewater inflow destination is switched to the high-load adjustment tank 12, the transfer pump 20 continues to send the wastewater from the adjustment tank 2 to the wastewater treatment equipment 3, and the calculation unit 6 continues to estimate the TOC concentration at the outlet of the adjustment tank 1, the TOC concentration at the wastewater treatment inflow, and the wastewater load.

[0067] Thereafter, when the estimated wastewater load falls below the threshold, the wastewater inflow destination is switched from the high-load adjustment tank 12 to the adjustment tank 2. The calculation unit 6 also controls the transfer pump 19 to adjust the timing of sending high-load wastewater from the high-load adjustment tank 12 to the wastewater treatment equipment 3 so as not to cause the wastewater treatment to fail. When the wastewater load when the wastewater from the adjustment tank 2 is mixed with the wastewater from the high-load adjustment tank 12 is less than a predetermined threshold, the calculation unit 6 sends water from the high-load adjustment tank 12. When the wastewater load after mixing is equal to or greater than the threshold, the water is not sent from the high-load adjustment tank 12 and is left stored.

[0068] In the configuration of Fig. 7, the opening and closing of valves 7A and 7B was controlled to switch the inflow destination of wastewater sent from adjustment tank 1, but as shown in Fig. 8, a transfer pump 18A that sends water from adjustment tank 1 to adjustment tank 2 and a transfer pump 18B that sends water from adjustment tank 1 to high-load adjustment tank 12 may be provided, and the on / off of transfer pumps 18A and 18B may be controlled to switch whether wastewater is sent into adjustment tank 2 or high-load adjustment tank 12. The calculation unit 6 may display the on / off timing of transfer pumps 18A and 18B on a monitor screen or the like so that the operator can see it, and the pumps may be operated manually according to the display.

[0069] In the configuration shown in Figure 7, the wastewater in the high-load adjustment tank 12 is sent to the wastewater treatment equipment 3 when the wastewater load becomes low. However, as shown in Figure 9, the wastewater in the high-load adjustment tank 12 may also be sent to the adjustment tank 2.

[0070] In the configuration of Figure 9, the opening and closing of valves 7A and 7B was controlled to switch the destination of the wastewater pumped from adjustment tank 1, but as shown in Figure 10, a transfer pump 18A that pumps water from adjustment tank 1 to adjustment tank 2, and a transfer pump 18B that pumps water from adjustment tank 1 to high-load adjustment tank 12 may be provided, and the starting and stopping of transfer pumps 18A and 18B may be controlled to switch whether the wastewater from adjustment tank 1 flows into adjustment tank 2 or high-load adjustment tank 12.

[0071] In the configurations shown in Figures 7 to 10, wastewater that is estimated to have a wastewater load of a predetermined value or more is branched downstream of the adjustment tank 1 and distributed to the high-load adjustment tank 12 arranged in parallel with the adjustment tank 2. If the wastewater is branched upstream of the adjustment tank 1 and distributed to the high-load adjustment tank 12, the wastewater quality fluctuates drastically and distribution to the high-load adjustment tank 12 is frequently performed, so that there is a possibility that the operation of opening and closing the valve and starting and stopping the transfer pump will be burdensome, especially when operating manually. Therefore, for the purpose of simplifying the distribution operation, it is preferable to distribute to the high-load adjustment tank 12 downstream of the adjustment tank 1.

[0072] 7 to 10, the HRT of the adjustment tank 1 is preferably 30 to 60 minutes. If the HRT is less than 60 minutes, the function of leveling the water quality in the adjustment tank 1 is low, and it is considered that no difference in the frequency or effect of distribution will occur whether the adjustment tank 1 is branched to the high-load adjustment tank 12 on the upstream or downstream side of the adjustment tank 1. Therefore, in this case, it is preferable to level the water quality and distribute high-load wastewater by branching on the downstream side of the adjustment tank 1 and arranging the adjustment tank 2 and the high-load adjustment tank in parallel.

[0073] In addition, the HRT of the adjustment tank 2 is preferably about 60 minutes to 30 hours. If the HRT is 60 minutes or more, it is considered that the water quality is sufficiently leveled, but if it is estimated that the wastewater load will exceed a predetermined value despite the leveling, the wastewater treatment can be stabilized by allocating the wastewater to the high-load adjustment tank 12 in advance. On the other hand, if the HRT exceeds 30 hours, it is unlikely that the wastewater load will exceed a predetermined value, and it is considered that there is no need to allocate the wastewater to the high-load adjustment tank 12.

[0074] In the configuration shown in FIG. 11, wastewater is arbitrarily sent to the adjustment tank 2 and the adjustment tank 2' without considering the pollution load of the wastewater. When sending wastewater to the adjustment tank 2, the valve 7A is opened and the valve 7B is closed, and when sending wastewater to the adjustment tank 2', the valve 7A is closed and the valve 7B is opened. In addition, of the adjustment tank 2 and the adjustment tank 2', the wastewater is sent to the wastewater treatment equipment 3 from the adjustment tank to which the wastewater is not sent. Alternatively, as shown in FIG. 12, a transfer pump 18A that sends water from the adjustment tank 1 to the adjustment tank 2 and a transfer pump 18B that sends water from the adjustment tank 2 to the adjustment tank 2' may be provided, and the pumps may be started and stopped separately. When the calculation unit 6 judges that the wastewater load is high and the wastewater treatment may fail, the calculation unit 6 controls the transfer pumps 19' and 20' to adjust the flow rate of the wastewater sent from the adjustment tank 2 and the adjustment tank 2' so that the wastewater load (TOC concentration x flow rate) is such that the wastewater treatment does not fail.

[0075] Fig. 13 shows a configuration in which the adjustment tanks 2A and 2B of the wastewater treatment system shown in Fig. 3 are replaced with an adjustment tank 2 and a high-load adjustment tank 12, respectively. By controlling the opening and closing of valves 7A and 7B, it is possible to switch whether wastewater conveyed from the adjustment tank 1 flows into the adjustment tank 2 or the high-load adjustment tank 12.

[0076] The calculation unit 6 acquires the TOC concentration measured by the pollution load measuring unit 4 and the flow rate of the wastewater flowing into the high-load adjustment tank 12 measured by the fourth flow rate measuring unit 13, and estimates the TOC concentration in the high-load adjustment tank 12 by the above-mentioned estimation method (3)-3.

[0077] The calculation unit 6 uses the estimated TOC concentration in the high-load adjustment tank 12, the flow rate measured by the fifth flow measurement unit 15, the TOC concentration measured by the pollution load measurement unit 4, and the flow rate measured by the first flow measurement unit 5 to estimate the TOC concentration at the outlet of the adjustment tank 1 by the above-mentioned estimation method (2)-3 or (3)-4.

[0078] Next, the calculation unit 6 uses the estimated TOC concentration at the outlet of the adjustment tank 1 and the flow rate of the wastewater flowing into the adjustment tank 2 measured by the third flow measurement unit 8 to estimate the TOC concentration at the wastewater treatment inlet (outlet of the adjustment tank 2) by any of the above estimation methods (1)-3, (2)-4, or (3)-5.

[0079] Then, the calculation unit 6 estimates the wastewater load from the estimated TOC concentration at the inlet of the wastewater treatment and the flow rate at the inlet of the wastewater treatment measured by the second flow rate measurement unit 10 using the above formula 1.

[0080] Under normal circumstances, wastewater from the adjustment tank 1 flows into the adjustment tank 2. When the calculation unit 6 determines that the estimated wastewater load is equal to or greater than a predetermined threshold and that the wastewater treatment may fail, it closes valve 7A and opens valve 7B to allow the wastewater sent from the adjustment tank 1 to flow into the high-load adjustment tank 12. Even after the wastewater inflow destination is switched to the high-load adjustment tank 12, the transfer pump 20 continues to send the wastewater from the adjustment tank 2 to the wastewater treatment equipment 3, and the calculation unit 6 continues to estimate the wastewater load.

[0081] Thereafter, when the estimated wastewater load falls below the threshold, the wastewater inflow destination is switched from the high-load adjustment tank 12 to the adjustment tank 2. The calculation unit 6 also controls the transfer pump 19 to adjust the timing of sending high-load wastewater from the high-load adjustment tank 12 to the adjustment tank 1 so as not to cause the wastewater treatment to fail. If the wastewater load when the wastewater from the high-load adjustment tank 12 is returned to the adjustment tank 1 is less than a predetermined threshold, the calculation unit 6 sends the water from the high-load adjustment tank 12 to the adjustment tank 1. If the wastewater load becomes equal to or greater than the threshold due to the return, the water is not sent from the high-load adjustment tank 12 and is left stored.

[0082] In the configuration of Figure 13, the opening and closing of valves 7A and 7B was controlled to switch the destination of the wastewater pumped from adjustment tank 1, but as shown in Figure 14, a transfer pump 18A that pumps water from adjustment tank 1 to adjustment tank 2, and a transfer pump 18B that pumps water from adjustment tank 1 to high-load adjustment tank 12 may be provided, and the starting and stopping of transfer pumps 18A and 18B may be controlled to switch whether the wastewater from adjustment tank 1 flows into adjustment tank 2 or high-load adjustment tank 12.

[0083] According to the present embodiment configured as described above, high-load wastewater equal to or greater than a preset threshold is distributed to the high-load adjustment tank, so that the wastewater load of the subsequent wastewater treatment stage does not exceed a set value. The wastewater distributed to the high-load adjustment tank is mixed with raw water so that the wastewater load does not exceed the set threshold, so that the wastewater treatment stage does not exceed the set value. This is expected to stabilize the wastewater treatment.

[0084] In the above embodiment, a configuration was described in which the calculation unit 6 performs calculations such as estimating the pollution load at the inlet of the wastewater treatment process and estimating the wastewater load at the inlet of the wastewater treatment process. However, the calculation unit 6 may be configured as a single computer, or may perform distributed processing using multiple computers.

[0085] The present invention is not limited to the above-described embodiment, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0086] 1,2,2´ Adjustment tank 3 Wastewater treatment facilities 4. Pollutant Load Measurement Section 5 1st flow rate measuring section 6 Arithmetic section 8 Third flow measurement section 10 2nd flow rate measuring section 11,19,19´,20,20´ Transfer pump 12 High load adjustment tank 13 4th flow measurement section 15 5th flow measurement section

Claims

1. A wastewater treatment method in which wastewater is flowed into an adjustment tank and sent from the adjustment tank to a wastewater treatment facility, Water quality items or operational management items related to wastewater load are continuously or periodically measured, and the wastewater load at the wastewater inlet (wastewater treatment inlet) to the wastewater treatment facility is estimated using a preset calculation formula based on the measured values; If the estimated wastewater load is less than a predetermined threshold, the wastewater is supplied to the adjustment tank; When the estimated wastewater load is equal to or greater than the threshold value, the wastewater is branched at a wastewater branch position upstream of the adjustment tank and stored in a high-load adjustment tank.

2. The wastewater treatment method according to claim 1 , wherein the water quality items or operational management items related to the wastewater load include a pollution load of the wastewater or an item correlated with the pollution load, and a wastewater flow rate flowing into the wastewater treatment facility.

3. The wastewater treatment method according to claim 1, wherein when the wastewater load when the water is sent from the high-load adjustment tank and joined downstream of the wastewater branch position becomes equal to or less than a predetermined threshold value, the water is sent from the high-load adjustment tank.

4. The wastewater treatment method according to claim 3 , wherein water is conveyed from the high-load adjustment tank to join a downstream side of the adjustment tank.

5. The wastewater treatment method according to claim 3 , wherein water is conveyed from the high-load adjustment tank to the adjustment tank.

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