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 the wastewater treatment plant, allocates high-load wastewater to a separate storage 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] The concentration and volume of wastewater discharged from beverage, food, and other manufacturing plants often fluctuate greatly depending on the product, production volume, and elapsed time for cleaning the production line. The optimal operating conditions for wastewater treatment often differ depending on the wastewater load, and large fluctuations in wastewater load can affect the treatment status.

[0003] In particular, organic wastewater is generally treated using biological treatment methods such as aerobic and 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] Furthermore, in physicochemical treatments 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] In the past, operators would periodically collect and analyze wastewater to determine the wastewater load at the inlet 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, or reducing the amount of wastewater inflow to the wastewater treatment plant. However, this method was always done manually, making continuous measurement impossible, and the inflow of high-load wastewater could be overlooked or measures delayed, leading to the breakdown of the wastewater treatment system and a deterioration in the quality of the treated water. Therefore, it is extremely important to continuously monitor the load of inflowing wastewater and take prompt measures to prevent the wastewater treatment system from breaking down.

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

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-282889 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 that can stably treat wastewater. [Means for solving the problem]

[0009] [1] A wastewater treatment method in which wastewater flows into an adjustment tank and is sent from the adjustment tank to a wastewater treatment facility, Water quality items or operational management items related to wastewater loads are measured continuously or periodically, and the wastewater load at the wastewater inlet (wastewater treatment inlet) to the wastewater treatment facility is estimated using a predetermined 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], wherein when the wastewater load is equal to or less than a predetermined threshold when water is sent from the high-load adjustment tank and joined downstream of the wastewater branch position, water is sent from the high-load adjustment tank.

[0012] [4] The wastewater treatment method according to [3], wherein water is sent 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 sent from the high-load adjustment tank to the adjustment tank. [Effects of the Invention]

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

[0015] [Figure 1] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Figure 2] FIG. 1 is a schematic configuration diagram of a wastewater treatment system according to a reference technology. [Figure 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. [Figure 5] FIG. 2 is a schematic configuration diagram of the 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 the wastewater treatment system according to the embodiment. [Figure 9]FIG. 2 is a schematic configuration diagram of the wastewater treatment system according to the embodiment. [Figure 10] FIG. 2 is a schematic configuration diagram of the 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 the wastewater treatment system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] A wastewater treatment system according to an embodiment of the present invention receives wastewater in an equalization tank and sends the wastewater from the equalization tank to a wastewater treatment facility. The system measures the pollution load upstream of the equalization tank, the flow rate of wastewater flowing into the equalization 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 to prevent the wastewater treatment from failing, and the high-load wastewater is sent at a time when the wastewater load is low, thereby stabilizing the wastewater treatment.

[0017] One or more equalizing tanks are provided, and as described below, multiple equalizing tanks 1 may be arranged in parallel or in series. Specifications such as the volume of the equalizing tank are not particularly limited. Furthermore, the treatment method and number of systems in the wastewater treatment facility are not particularly limited. Examples of treatment methods 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 equalizing tank 1 and a wastewater treatment facility 3 installed after (downstream of) the equalizing tank 1, the pollutant load of the wastewater is measured by a pollution load measuring unit 4 installed before (upstream of) the equalizing tank 1. In addition, a first flow rate measuring unit 5 is used to measure the flow rate of the wastewater flowing into the equalizing 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 in order to adjust and mitigate fluctuations in water quality and water volume.

[0021] In this embodiment, an example will be described in which TOC concentration is measured as the pollution load, 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. Furthermore, 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 water supply type, 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 type, 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 flow 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 water level per unit time in the adjustment tank 1.

[0024] The pollution load measuring unit 4, the first flow rate measuring unit 5, and the second flow rate measuring unit 10 measure continuously or periodically at relatively short time intervals the pollution load or items correlated therewith, which are water quality items or operational management items related to the 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.

[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 wastewater treatment inlet 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, 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 plant 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 50 minutes ago can be considered to be the TOC concentration at the inlet of the wastewater treatment plant (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 complete 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 has 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 time the inlet valve is "open" to "closed" or while the pump is running. If it is difficult to obtain the valve open / close signal or the pump start / stop signal, it is also possible to determine the timing at which wastewater is flowing into the equalization tank 1 from changes in the water level.

[0030] The calculation unit 6 estimates the wastewater load (kg-TOC / day) using the following equation 1 from 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 rate measurement unit 10.

[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 Figure 2, when an equalization tank 2 is installed in series with the equalization tank 1 between the equalization tank 1 and the wastewater treatment equipment 3, the TOC concentration (estimated value A) at the outlet of the equalization tank 1 is first estimated. One or more equalization tanks 2 may be installed, and as described below, multiple equalization tanks 2 may be arranged in parallel. The specifications of the equalization tank 2, such as its volume, are not particularly limited. As in Figure 1, the estimation method differs depending on whether the equalization tank 1 is a continuous or batch-flow system. In the case of continuous flow, the TOC concentration (estimated value A) at the outlet of the equalization tank 1 is estimated using the above-mentioned estimation method (1)-1 or (2)-1, and in the case of batch-flow, the TOC concentration is estimated using estimation method (3)-1.

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

[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 equalization tank 2.

[0035] Estimation method (2)-2 From the TOC concentration (estimated value A) and the flow rate flowing into equalization tank 2, the change in the wastewater concentration flowing into equalization tank 2 is estimated using a perfect mixing tank model, 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 inlet of the wastewater treatment plant.

[0037] The third flow rate measuring unit 8, which measures the flow rate of wastewater flowing into the equalizing tank 2, may be a flow meter, or, if the equalizing tank 2 is a batch-flow type, may be calculated from the increase in water level per unit time in the equalizing tank 2. Alternatively, if the equalizing tank 2 is a continuous-flow type, the flow rate of wastewater flowing into the equalizing tank 2 may be calculated from the sum of the change in the storage volume of the equalizing tank 2 and the discharge flow rate from the equalizing 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 rate measuring unit 10.

[0039] Next, as shown in Figure 3, consider the case where equalization tanks 2A and 2B are installed 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 of equalization tank 1 flows into equalization tank 2A ​​or 2B. Wastewater flowing out of equalization tank 2A ​​flows into wastewater treatment equipment 3. Wastewater flowing out of 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 with a flow meter or calculated from the amount of increase in 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 with a flow meter or calculated from the amount of decrease in 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 tanks or batch water supply tanks. One or more adjustment tanks 2A may be provided, and multiple 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 calculated by dividing the total water volume (m 3 ) to estimate the TOC concentration (mg / L) in the 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 Using 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, the change in the wastewater concentration flowing into equalization tank 1 is estimated using a perfect mixing tank model, 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 was 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 equalization tank 2A) is estimated from the TOC concentration (estimated value D) at the outlet of the equalization tank 1 obtained as described above and the flow rate into the equalization tank 2A. If the equalization tank 2A ​​is a continuous water supply, the TOC concentration (estimated value E) at the wastewater treatment inlet is estimated using estimation method (1)-3 or (2)-4, and if the equalization tank 2A ​​is a batch water supply, the TOC concentration (estimated value E) at the wastewater treatment inlet is estimated using estimation method (1)-3 or (2)-4.

[0048] Estimation method (1)-3 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 D) over a period close to the residence time in the equalization tank 2A.

[0049] Estimation method (2)-4 From the TOC concentration (estimated value D) and the flow rate flowing into the equalization tank 2A, the change in the wastewater concentration flowing into the equalization tank 2A ​​is estimated using a perfect mixing tank model, 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 rate measuring unit 10.

[0052] According to this embodiment, the pollution load (or items correlated with the pollution load) upstream 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 wastewater treatment inlet is estimated using these. Based on 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 above the threshold, it is distributed to a high-load adjustment tank, and if it is below the threshold, it is distributed to a normal adjustment tank. The threshold is set under conditions that will not cause the wastewater treatment to fail, such as being below 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 also be included in determining the threshold. For example, if the current wastewater load is above the set threshold A and the wastewater load from several hours ago was above 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 be mixed with wastewater, if the wastewater load at the wastewater treatment inlet is added to the wastewater load sent from the high-load adjustment tank and the total is less than the set threshold, water is sent from the high-load adjustment tank. Conversely, if the added load exceeds the threshold, the water is not sent and remains 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. The wastewater delivered by the transfer pump 11 branches off 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 plant by 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 plant using the estimated TOC concentration and the flow rate measured by the second flow rate measurement unit 10, and determines whether or not 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 inlet and the wastewater load.

[0059] Thereafter, when the estimated wastewater load falls below the threshold, the destination of the wastewater is switched from the high-load adjustment tank 12 to the adjustment tank 1. Furthermore, the calculation unit 6 controls the transfer pump 19 to adjust the timing of sending the 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 (confluent) 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 remains stored therein.

[0060] The calculation unit 6 may display the opening and closing timing of valves 17A and 17B on a monitor screen or the like, and an operator may manually control the opening and closing of valves 17A and 17B in accordance with the display. Similarly, the calculation unit 6 may display the water supply timing of transfer pumps 19 and 20 on a monitor screen or the like so that the operator can see the timing, and an operator may manually operate the pumps in accordance with the display. Also, instead of 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 wastewater from adjustment tank 1 and the high-load adjustment tank, allowing operation with a single transfer pump.

[0061] In the configuration shown in Figure 4, a configuration has been described in which wastewater in the high-load adjustment tank 12 is sent to the wastewater treatment equipment 3, but as shown in Figure 5, 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 sent to adjustment tank 1 and adjustment tank 1' at will without considering the pollution load of the wastewater. When sending wastewater to adjustment tank 2, valve 7A is opened and valve 7B is closed. When sending wastewater to adjustment tank 2', valve 7A is closed and valve 7B is opened. In addition, of adjustment tanks 2 and 2', wastewater is sent to wastewater treatment equipment 3 from the adjustment tank that is not sending wastewater. If calculation unit 6 determines that the wastewater load is high and the wastewater treatment may fail, it controls transfer pumps 19' and 20' to adjust the flow rate of wastewater sent from adjustment tank 1 and adjustment tank 1' so that the wastewater load (TOC concentration × flow rate) is achieved without causing the wastewater treatment to fail. Calculation unit 6 displays the water flow rates of transfer pumps 19' and 20' on a monitor screen or the like so that the operator can see them, and the pumps can be operated manually according to the display. In addition, instead of 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 point where the wastewater from the adjustment tank 1 and the high-load adjustment tank 12 join, thereby making it possible to operate the system with a single transfer pump.

[0063] Figure 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 Figure 2. By controlling the opening and closing of valves 7A and 7B, it is possible to switch whether the 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 using 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 one of the above estimation methods (1)-2, (2)-2, or (3)-2, using the estimated TOC concentration at the outlet of the equalization tank 1 and the flow rate of the wastewater flowing into the equalization 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 equation 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 adjustment tank 1 flows into adjustment tank 2. When 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, causing the wastewater sent from adjustment tank 1 to flow into high-load adjustment tank 12. Even after the wastewater inflow destination is switched to high-load adjustment tank 12, the transfer pump 20 continues to send the wastewater from adjustment tank 2 to wastewater treatment equipment 3, and calculation unit 6 continues to estimate the TOC concentration at the outlet of adjustment tank 1, the TOC concentration at the wastewater treatment inlet, and the wastewater load.

[0067] Thereafter, when the estimated wastewater load falls below the threshold, the destination of the wastewater is switched from the high-load adjustment tank 12 to the adjustment tank 2. Furthermore, the calculation unit 6 controls the transfer pump 19 to adjust the timing of sending the 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. If the wastewater load when the wastewater from the adjustment tank 2 is mixed with the wastewater from the high-load adjustment tank 12 is below a predetermined threshold, the calculation unit 6 sends water from the high-load adjustment tank 12. If 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 remains stored therein.

[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 delivered from adjustment tank 1, but as shown in Fig. 8, a transfer pump 18A that delivers water from adjustment tank 1 to adjustment tank 2 and a transfer pump 18B that delivers 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 the wastewater is delivered to 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 timing can be seen, and an operator may manually operate the pumps 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, but 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 sent from adjustment tank 1, but as shown in Figure 10, 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 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 above a predetermined value is branched downstream of the adjustment tank 1 and distributed to a 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 will fluctuate greatly and distribution to the high-load adjustment tank 12 will be frequent, which can impose a burden on operations, particularly when operating manually, in terms of opening and closing valves and starting and stopping transfer pumps. Therefore, in order to simplify the distribution operation, it is preferable to distribute the wastewater 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 60 minutes or less, the function of leveling the water quality in the adjustment tank 1 is low, and it is thought that there will be little difference in the frequency and effectiveness of distribution whether the water 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 desirable to branch off on the downstream side of the adjustment tank 1 and install the adjustment tank 2 and the high-load adjustment tank in parallel to level the water quality and distribute the high-load wastewater.

[0073] Furthermore, 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 thought that the water quality will be sufficiently equalized, but if it is estimated that the wastewater load will exceed a predetermined value despite equalization, the wastewater treatment can be stabilized by allocating the wastewater in advance to the high-load adjustment tank 12. 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 thought 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 adjustment tank 2 and adjustment tank 2' without considering the pollution load of the wastewater. When sending wastewater to adjustment tank 2, valve 7A is opened and valve 7B is closed. When sending wastewater to adjustment tank 2', valve 7A is closed and valve 7B is opened. Furthermore, of adjustment tanks 2 and 2', the one to which wastewater is not being sent sends wastewater to wastewater treatment equipment 3. Alternatively, as shown in FIG. 12, transfer pump 18A that sends water from adjustment tank 1 to adjustment tank 2 and transfer pump 18B that sends water from adjustment tank 2 to adjustment tank 2' may be provided, and the pumps may be started and stopped separately. If calculation unit 6 determines that the wastewater load is high and that wastewater treatment may fail, it controls transfer pumps 19' and 20' to adjust the flow rate of wastewater sent from adjustment tank 2 and adjustment tank 2' so that the wastewater load (TOC concentration × flow rate) is such that wastewater treatment will 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 the wastewater conveyed from adjustment tank 1 flows into adjustment tank 2 or high-load adjustment tank 12.

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

[0077] The calculation unit 6 uses the estimated TOC concentration of the high-load adjustment tank 12, the flow rate measured by the fifth flow rate measurement unit 15, the TOC concentration measured by the pollution load measurement unit 4, and the flow rate measured by the first flow rate measurement unit 5 to estimate the TOC concentration at the outlet of the adjustment tank 1 using 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 rate measurement unit 8 to estimate the TOC concentration at the wastewater treatment inlet (outlet of the adjustment tank 2) using one 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 wastewater treatment inlet and the flow rate at the wastewater treatment inlet measured by the second flow rate measurement unit 10 using the above formula 1.

[0080] Under normal circumstances, wastewater from adjustment tank 1 flows into adjustment tank 2. When 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, causing the wastewater sent from adjustment tank 1 to flow into high-load adjustment tank 12. Even after the wastewater inflow destination has been switched to high-load adjustment tank 12, the transfer pump 20 continues to send the wastewater from adjustment tank 2 to wastewater treatment equipment 3, and calculation unit 6 continues to estimate the wastewater load.

[0081] Thereafter, when the estimated wastewater load falls below the threshold, the destination of the wastewater 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 the 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 below 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 exceeds the threshold due to the return, the water is not sent from the high-load adjustment tank 12 and remains 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 sent from adjustment tank 1, but as shown in Figure 14, 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 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, by allocating high-load wastewater exceeding a preset threshold to the high-load adjustment tank, it is possible to prevent the wastewater load in the subsequent wastewater treatment from exceeding a set value. By mixing the wastewater allocated to the high-load adjustment tank with raw water so as not to exceed the set threshold, it is possible to treat the wastewater while preventing the wastewater load in the subsequent wastewater treatment from exceeding a 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 plant and estimating the wastewater load at the inlet of the wastewater treatment plant, but the calculation unit 6 may be configured as a single computer, or may be configured as a distributed processing unit using multiple computers.

[0085] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0086] 1,2,2´ Adjustment tank 3 Wastewater treatment facilities 4. Pollution Load Measurement Section 5 1st flow rate measuring section 6 Arithmetic section 8 Third flow measurement section 10 2nd flow measurement 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 flows into an adjustment tank and is sent from the adjustment tank to wastewater treatment equipment, The water quality items related to the wastewater load, the flow rate of the wastewater flowing into the adjustment tank, and the flow rate of the wastewater flowing into the wastewater treatment facility 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 predetermined 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 related to the wastewater load include a pollution load of the wastewater or an item correlated with the pollution load, and the pollution load includes any one of a TOC concentration, a COD concentration, and an SS concentration.

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

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

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

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