Method for estimating wastewater load and method for treating wastewater

Abstract

To provide a method for treating wastewater capable of reducing an amount of industrial waste by mixing a concentrated waste liquid with wastewater and performing wastewater treatment, and to provide a method for accurately estimating a wastewater load at a wastewater inflow section of a wastewater treatment facility that treats a mixed liquid of wastewater and a concentrated waste liquid.SOLUTION: A method includes estimating a wastewater load at a wastewater treatment inflow section of a wastewater treatment facility that treats a mixed liquid where wastewater and a concentrated waste liquid are merged. The method includes: measuring a first pollution load of wastewater; estimating a pollution load derived from the wastewater at a merging point of the wastewater and the concentrated waste liquid or a predetermined position downstream of this point based on the first pollution load; measuring a second pollution load of the concentrated waste liquid; estimating a pollution load of the concentrated waste liquid at the merging point or the predetermined position based on the second pollution load; and estimating the wastewater load based on an estimated value of the pollution load derived from wastewater at the merging point or the predetermined position and an estimated value of the pollution load of the concentrated waste liquid.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for estimating a wastewater load at a wastewater treatment inlet of a wastewater treatment facility, a wastewater treatment method for stabilizing the wastewater treatment by adjusting the inflow rate to the wastewater treatment based on the estimated wastewater load, and a method for reducing the amount of industrial waste. [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] It has also been confirmed that high-load wastewater has been disposed of as industrial waste without undergoing wastewater treatment. For example, Patent Document 1 (JP Patent Publication No. 11-197664) describes that wastewater with a very high pollution load and the possibility of wastewater treatment failing (hereinafter referred to as "thick wastewater"), such as the saltwater processing liquid generated during the processing of pickled plums, has been conventionally disposed of as industrial waste. However, the method of disposing of it as industrial waste has problems such as the high cost of industrial waste treatment and the global environmental destruction caused by carbon dioxide and the like generated from industrial waste, and there has been a demand to reduce the amount of thick wastewater to be disposed of as industrial waste.

[0007] Patent Document 2 (JP Patent Publication 2006-334491A) describes a method of processing food residues into a form that can be treated as wastewater without being treated as industrial waste in order to reduce the amount of industrial waste, and controlling the amount of food residues fed into a normal wastewater treatment system based on the measured TOC concentration so that the wastewater treatment does not fail. However, Patent Document 2 clearly states that the TOC concentration is measured in an adjustment tank after the food residues merge with the normal wastewater treatment system, and the amount of food residues fed is adjusted so that the TOC concentration falls within a specified range, but there is a possibility that the TOC concentration in the normal wastewater treatment system may rise instantaneously and thus exceed the specified range at the time the measured value is obtained. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 11-197664 [Patent Document 2] JP 2006-334491 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a wastewater treatment method that can reduce the amount of industrial waste by mixing concentrated wastewater, which has conventionally been disposed of as industrial waste, with wastewater and treating the resulting mixture, and a method for accurately estimating the wastewater load at the wastewater inlet of a wastewater treatment facility that treats a mixture of wastewater and concentrated wastewater. [Means for solving the problem]

[0010] The method for estimating wastewater load according to the present invention is a method for estimating the wastewater load at the wastewater treatment inlet of a wastewater treatment facility that treats a mixed liquid obtained by joining wastewater and concentrated wastewater, comprising measuring a first pollution load of the wastewater, estimating a pollution load originating from the wastewater at the confluence of the wastewater and concentrated wastewater or a specified position downstream thereof based on the first pollution load, measuring a second pollution load of the concentrated wastewater, estimating a pollution load of the concentrated wastewater at the confluence or the specified position based on the second pollution load, and estimating the wastewater load based on the estimated pollution load originating from the wastewater and the estimated pollution load of the concentrated wastewater at the confluence or the specified position.

[0011] In one aspect of the present invention, wastewater is fed to the wastewater treatment facility via an adjustment tank, the confluence is located downstream of the adjustment tank, and the first pollution load is measured upstream of the adjustment tank.

[0012] In one aspect of the present invention, a first flow rate of wastewater flowing into the adjustment tank is measured, and the pollution load of the wastewater at the confluence is estimated using the first pollution load and the first flow rate.

[0013] In one embodiment of the present invention, concentrated waste liquid is pumped from a concentrated waste liquid tank to the confluence, the second pollution load is measured in the concentrated waste liquid tank, and the pollution load of the concentrated waste liquid at the confluence is estimated from the second pollution load.

[0014] In the wastewater treatment method of the present invention, when the wastewater load estimated by the above method is equal to or greater than a predetermined value, the concentrated wastewater is not sent to the junction.

[0015] In one aspect of the present invention, when the estimated wastewater load is less than a predetermined value, the concentrated wastewater is fed to the junction at a flow rate not exceeding the predetermined value. Effect of the Invention

[0016] According to the present invention, the amount of industrial waste can be reduced by mixing the concentrated wastewater with wastewater and treating the mixture. Also, according to the present invention, the wastewater load at the wastewater inlet of the wastewater treatment facility that treats the mixture of wastewater and concentrated wastewater can be accurately estimated. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a wastewater treatment system according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a schematic configuration diagram of a wastewater treatment system according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a schematic configuration diagram of a wastewater treatment system according to a third embodiment of the present invention. [Figure 4] FIG. 11 is a schematic configuration diagram of a wastewater treatment system according to a fourth embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic configuration diagram of a wastewater treatment system according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] [First embodiment] As shown in FIG. 1, the wastewater treatment system according to the first embodiment of the present invention includes an adjustment tank 1, a wastewater inlet pipe 23 connected to the upstream side of the adjustment tank 1 and transporting wastewater to the adjustment tank 1, a first pollution load measuring unit 4 provided in the wastewater inlet pipe 23 and measuring the pollution load of the wastewater flowing into the adjustment tank 1, a first flow rate measuring unit 5 also provided in the wastewater inlet pipe 23 and measuring the flow rate of the wastewater flowing into the adjustment tank 1, a wastewater discharge pipe 24 through which the wastewater discharged from the adjustment tank 1 flows into the wastewater treatment plant, a concentrated wastewater tank 17 for storing concentrated wastewater, a concentrated wastewater inlet pipe 25 connected to the upstream side of the concentrated wastewater tank 17 and transporting the concentrated wastewater to the concentrated wastewater tank 17, and a concentrated wastewater discharge pipe 26 provided in the concentrated wastewater tank 17. The system includes a second pollution load measuring unit 18 for measuring the pollution load of the liquid, a thick waste liquid discharge pipe 26 for merging the thick waste liquid discharged from the thick waste liquid tank 17 with the wastewater discharge pipe 24, a second flow rate measuring unit 19 provided in the thick waste liquid discharge pipe 26 for measuring the flow rate of the thick waste liquid discharged from the thick waste liquid tank 17, a wastewater treatment facility 3 for treating a mixed liquid in which the thick waste liquid is mixed with the wastewater, a third flow rate measuring unit 10 provided upstream of the junction with the thick waste liquid in the wastewater discharge pipe 24 for measuring the flow rate of the wastewater discharged from the adjustment tank 1, and a calculation unit 6 for estimating the wastewater load at the inlet of the wastewater treatment facility 3 (downstream of the junction with the thick waste liquid in the wastewater discharge pipe 24). The calculation unit 6 is, for example, a computer. The calculation unit 6 acquires the measurement results of various measuring instruments. The calculation unit 6 also controls the opening and closing of valves and the starting and stopping of pumps, which will be described later.

[0020] Wastewater from a single line flows into the adjustment tank 1, or wastewater from multiple lines flows into the adjustment tank 1 after being merged into the wastewater inlet pipe 23 simultaneously or at different times. There are no particular limitations on the quality of the wastewater flowing into the adjustment tank 1, but if the wastewater continues to have at least one of the following conditions for a certain period of time (e.g., more than 20% of the total inflow period of the wastewater): water temperature of 40°C or higher, pH of 4 or lower or pH of 9 or higher, and ORP of 750 mV or higher, then slime adhesion to the first pollution load measuring unit 4 and the first flow rate measuring unit 5 is suppressed, and measurement errors due to slime are prevented, making it easier to obtain the effects of the invention.

[0021] The first pollution load measuring unit 4 measures the pollution load of the wastewater flowing into the adjustment tank 1 periodically or continuously at relatively short time intervals. In this embodiment, an example in which TOC concentration is measured 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 specific substance concentration, COD concentration, and SS. The pollution load to be measured also includes items correlated with the pollution load, such as electrical conductivity and Brix sugar content.

[0022] The first pollution load measuring section 4 is located upstream of the adjustment tank 1, and in the case of multiple systems, downstream of the confluence of the wastewater from each system, and measures the pollution load (TOC concentration) by immersing an instrument in the wastewater.

[0023] The adjustment tank 1 is defined as having an HRT (hydraulic retention time) of 30 minutes or more for the purpose of adjusting and mitigating fluctuations in water quality and water volume. The specifications of the adjustment tank 1, such as its volume, are not particularly limited. A plurality of adjustment tanks 1 may be arranged in parallel.

[0024] The first flow rate measuring unit 5 that measures the flow rate of wastewater flowing into the adjustment tank 1 may be a flow meter, or, if the adjustment tank 1 is a batch-flow type, may be calculated from the amount of increase in water level per unit time in the adjustment tank 1. If the adjustment tank 1 is a continuous-flow 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 1. In this case, it is necessary to install a level meter in the adjustment tank 1 as the first flow rate measuring unit 5.

[0025] The thick wastewater tank 17 is a tank for storing thick wastewater with such a high pollution load that it cannot be treated by itself. Thick wastewater from a single line flows into the thick wastewater tank 17, or thick wastewater from multiple lines flows into the thick wastewater inlet pipe 25 at the same time or at different times. The thick wastewater is stored in the tank 17 at a concentration of 1000 to 2000 MPa (1000 to 2000 MPa) at a concentration of 1000 to 2000 MPa (1000 to 2000 MPa). The pollution load is higher. The specifications such as the volume of the thick waste liquid tank 17 and the number are not particularly limited. The thick waste liquid tank 17 is not a permanent tank, and a container such as a mobile container may be used, and the container storing the thick waste liquid may be moved to the wastewater treatment system of the present invention at the site where the thick waste liquid is discharged and treated temporarily. Alternatively, the container storing the thick waste liquid may be moved to the wastewater treatment system of the present invention and the thick waste liquid may be directly introduced from the container to the permanent thick waste liquid tank 17. In these cases, the thick waste liquid inlet pipe 25 is not required. The thick waste liquid is, for example, pickled plum salt water processing liquid generated during pickled plum processing, waste syrup liquid generated during beverage manufacturing, plating waste liquid, etc.

[0026] The second pollution load measuring unit 18 measures the pollution load of the concentrated liquid waste in the concentrated liquid waste tank 17 periodically at relatively short time intervals or continuously. For example, the second pollution load measuring unit 18 measures the pollution load of the same measurement items as those of the first pollution load measuring unit 4. As described above, in this embodiment, the TOC concentration is measured as the pollution load.

[0027] There is no particular limit to the method for measuring the TOC concentration of the concentrated wastewater, and the TOC concentration may be measured by dilution, or another correlated index may be measured. The second pollution load measuring unit 18 may measure the pollution load (TOC concentration) by immersing an instrument in the concentrated wastewater.

[0028] The second flow rate measuring unit 19 measures the flow rate of the thick waste liquid flowing from the thick waste liquid tank 17 into the wastewater treatment facility 3. The second flow rate measuring unit 19 may measure the flow rate with a flow meter, or may calculate the flow rate using the amount of decrease in the water level per unit time in the thick waste liquid tank 17. In this case, it is necessary to install a level meter in the thick waste liquid tank 17 as the second flow rate measuring unit 19. If the flow rate of the thick waste liquid is fixed at a specified value, measurement can be omitted.

[0029] A transfer pump 11 provided in the wastewater discharge piping 24 sends the wastewater in the adjustment tank 1 to the wastewater treatment equipment 3. A third flow rate measurement unit 10 also provided in the wastewater discharge piping 24 measures the flow rate of the wastewater discharged from the adjustment tank 1. The third flow rate measurement unit 10 may be a flow meter, or may be one that calculates the flow rate using the amount of water level reduction per unit time in the adjustment tank 1. In this case, it is necessary to install a level meter in the adjustment tank 1 as the third flow rate measurement unit 10.

[0030] A transfer pump 20 provided in the thick waste liquid discharge pipe 26 sends the thick waste liquid in the thick waste liquid tank 17 to the wastewater flowing through the wastewater discharge pipe 24. The wastewater and the thick waste liquid join and mix, and the mixed liquid is sent to the wastewater treatment facility 3 through the wastewater discharge pipe 24. In the example shown in FIG. 1, the wastewater and the thick waste liquid are mixed downstream of the third flow rate measuring unit 10.

[0031] The wastewater treatment facility 3 removes dirt and oil contained in the mixed liquid formed by merging and mixing the wastewater with the concentrated waste liquid. There are no particular limitations on the treatment method and number of systems for the mixed liquid. Treatment methods include, for example, so-called biological treatment including aerobic and anaerobic treatment, physicochemical treatment such as Fenton treatment and activated carbon treatment, and, depending on the wastewater, neutralization treatment and coagulation separation treatment.

[0032] The calculation unit 6 estimates the TOC concentration at the 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.

[0033] The TOC concentration at the outlet of the equalization tank 1 can be estimated using the TOC concentration measured by the pollution load measuring unit 4 (the TOC concentration measured upstream of the equalization tank 1) 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 equalization tank 1 is a continuous water supply or batch water supply tank, for example, different estimation methods can be used, as described below.

[0034] <When water is continuously flowing> Estimation method (1)-1 The TOC concentration (mg / L) at the outlet of the equalization tank 1 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 discharged from the equalization tank 1.

[0035] 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 TOC concentration of the wastewater flowing into equalization tank 1, and the TOC concentration (mg / L) at the outlet of equalization tank 1 is estimated.

[0036] <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 outlet of the equalization tank 1. In order to accurately grasp the total TOC weight and total water volume that flowed into the equalization tank 1, it is desirable to obtain the inlet valve opening / closing signal of the equalization tank 1 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 opening / closing signal or the pump start / stop signal, it is also possible to grasp the timing when wastewater is flowing into the equalization tank 1 from the change in the water level in the equalization tank 1.

[0037] The calculation unit 6 estimates the wastewater load (kg-TOC / day) at the inflow (wastewater treatment inflow) of the wastewater treatment equipment 3 using the TOC concentration at the outlet of the adjustment tank 1 estimated by any of the above estimation methods (1)-1, (2)-1, or (3)-1, the flow rate at the outlet of the adjustment tank 1 measured by the third flow measurement unit 10, the TOC concentration of the thick wastewater measured by the second pollution load measurement unit 18, and the flow rate of the thick wastewater joining the wastewater treatment measured by the second flow measurement unit 19, using the following equation 1.

[0038] Equation 1: Wastewater load (kg-TOC / day) = {TOC concentration of wastewater at the outlet of the equalizing tank (mg / L) × flow rate of wastewater at the outlet of the equalizing tank (m 3 / h) + TOC concentration of the combined concentrated waste liquid (mg / L) × flow rate of the combined concentrated waste liquid (m 3 / h)}×24(h) / 1000

[0039] For the "TOC concentration of the concentrated waste liquid to be merged" in formula 1, the measurement result of the second pollution load measuring unit 18 may be used as is, but it is preferable to use the TOC concentration of the concentrated waste liquid at the junction estimated in consideration of the residence time from the TOC concentration measurement position (e.g., concentrated waste liquid tank 17) to the junction. For example, if the time it takes for the concentrated waste liquid to be discharged from the concentrated waste liquid tank 17 to reach the junction is one minute, the average of the TOC concentration measurement results of the second pollution load measuring unit 18 from the present to one minute ago can be estimated as the "TOC concentration of the concentrated waste liquid to be merged".

[0040] The calculation unit 6 judges whether or not it is problematic for the mixed liquid to flow into the wastewater treatment equipment 3 based on the estimated wastewater load at the wastewater treatment inlet. If the calculation unit 6 judges that the wastewater load is high (the wastewater load is equal to or greater than a predetermined value) and that the wastewater treatment may fail, it closes valve 21, opens valve 12, stops transfer pump 20, and leaves the concentrated wastewater stored in concentrated wastewater tank 17. The calculation unit 6 continues to estimate the wastewater load.

[0041] Thereafter, when the estimated wastewater load becomes low (below a predetermined value), the valve 21 is opened and the transfer pump 20 is controlled to send the concentrated wastewater from the concentrated wastewater tank 17 to the wastewater discharge pipe 24. The concentrated wastewater from the concentrated wastewater tank 17 is mixed with the wastewater from the adjustment tank 1 and flows into the wastewater treatment facility 3 through the wastewater discharge pipe 24. It is preferable to control the transfer pump 20 to adjust the flow rate and inflow timing of the concentrated wastewater sent from the concentrated wastewater tank 17 to the wastewater discharge pipe 24 so that the wastewater treatment does not fail. In this case, the concentrated wastewater is sent to the wastewater discharge pipe 24 while adjusting the flow rate and flow rate timing so that the estimated wastewater load does not exceed a predetermined value.

[0042] The calculation unit 6 may display on a monitor screen or the like the timing for starting and stopping the transfer pump 20 so that the operator can know the timing, and may manually operate the transfer pump 20 according to the display.

[0043] According to this embodiment, the pollution load (or items correlated with the pollution load) and flow rate of the wastewater are continuously measured upstream of the adjustment tank 1, and the pollution load (or items correlated with the pollution load) and flow rate of the concentrated wastewater directly flowing into the wastewater treatment plant downstream of the adjustment tank 1 are grasped. The load due to the wastewater and the load due to the concentrated wastewater are added together to estimate the wastewater load at the inlet of the wastewater treatment plant. The flow rate and timing of the inflow of the concentrated wastewater are adjusted based on this estimated value, thereby reducing the amount of industrial waste and stabilizing the wastewater treatment plant.

[0044] [Second embodiment] FIG. 2 shows a schematic configuration of a wastewater treatment system according to a second embodiment. This embodiment is different from the first embodiment shown in FIG. 1 in that an adjustment tank 2 is provided in series with the adjustment tank 1 between the adjustment tank 1 and the wastewater treatment equipment 3. This wastewater treatment system includes a relay pipe 27 connected to the downstream side of the adjustment tank 1 to transfer wastewater to the adjustment tank 2, and a fourth flow rate measuring unit 8 provided in the relay pipe 27 to measure the flow rate of wastewater flowing into the adjustment tank 2. The specifications of the adjustment tank 2, such as the volume, are not particularly limited. A plurality of adjustment tanks 2 may be arranged in parallel. In FIG. 2, the same parts as those in the first embodiment shown in FIG. 1 are given the same reference numerals and will not be described.

[0045] Wastewater sent from the adjustment tank 1 by the transfer pump 11 provided in the relay pipe 27 flows into the adjustment tank 2 through the relay pipe 27. The fourth flow rate measurement unit 8 measures the flow rate of the wastewater flowing into the adjustment tank 2. The fourth flow rate measurement unit 8 may be a flow meter, or, in the case where the adjustment tank 2 is a batch-wise water supply tank, it may be a unit that calculates the flow rate from the amount of increase in the water level per unit time in the adjustment tank 2. In the case where the adjustment tank 2 is a continuous water supply tank, 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. In this case, it is necessary to install a level meter in the adjustment tank 2 as the fourth flow rate measurement unit 8.

[0046] A transfer pump 13 provided in the wastewater discharge piping 24 sends the wastewater in the adjustment tank 2 to the wastewater treatment equipment 3. A third flow rate measuring unit 10 measures the flow rate of the wastewater at the outlet of the adjustment tank 2. Downstream of the third flow rate measuring unit 10, the wastewater sent out from the adjustment tank 2 and the concentrated waste liquid join and mix, and the mixed liquid flows into the wastewater treatment equipment 3 through the wastewater discharge piping 24.

[0047] In this configuration, the calculation unit 6 first estimates the TOC concentration at the outlet of the adjustment tank 1. As in the first embodiment shown in Fig. 1, the estimation method differs depending on whether the adjustment tank 1 is a continuous water supply or a batch water supply, and the TOC concentration (estimated value A) at the outlet of the adjustment tank 1 is estimated by the above estimation method (1)-1 or (2)-1 in the case of continuous water supply, and by estimation method (3)-1 in the case of batch water supply.

[0048] Next, the TOC concentration (estimated value B) at the 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 fourth flow rate 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 outlet of the adjustment tank 2, while in the case of batch water supply, estimation method (3)-2 is used.

[0049] Estimation method (1)-2 The TOC concentration (mg / L) at the outlet of equalization tank 2 is estimated by taking a moving average of the TOC concentration (estimated value A) over a period close to the residence time in equalization tank 2.

[0050] 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 TOC concentration of the wastewater flowing into equalization tank 2, and the TOC concentration (mg / L) at the outlet of equalization tank 2 is estimated.

[0051] Estimation method (3)-2 The total TOC weight (g) flowing into the adjustment tank 2 is expressed as the total water volume (m 3 ) to estimate the TOC concentration (mg / L) at the outlet of equalization tank 2.

[0052] Using the TOC concentration (estimated value B) at the outlet of the adjustment tank 2 thus obtained, the flow rate of the wastewater at the outlet of the adjustment tank 2 measured by the third flow rate measurement unit 10, and the TOC concentration and flow rate of the concentrated wastewater, the wastewater load (kg-TOC / day) is estimated by the above formula 1. In this embodiment, the "outlet of the adjustment tank" in formula 1 corresponds to the outlet of the adjustment tank 2.

[0053] The calculation unit 6 judges whether or not it is OK for the mixed liquid to flow into the wastewater treatment equipment 3 based on the estimated wastewater load at the wastewater treatment inlet. The calculation unit 6 controls the start / stop of the transfer pump 20 and the opening / closing of the valve 21, and adjusts the flow rate and inflow timing of the concentrated wastewater sent from the concentrated wastewater tank 17 to the wastewater discharge piping 24 so that the wastewater treatment does not fail. In this case, the concentrated wastewater is sent to the wastewater discharge piping 24 while adjusting the flow rate and flow rate timing so that the estimated wastewater load does not exceed a predetermined value.

[0054] 2 shows a configuration in which two levels of equalizing tanks (equipment tank 1, equalizing tank 2) are arranged in series, but three or more levels of equalizing tanks may be arranged in series. The more equalizing tanks arranged in series, the longer the time it takes for wastewater with the estimated wastewater load to actually reach the wastewater treatment facility 3, which is effective in that it is easier to take measures before the wastewater load exceeds a predetermined value.

[0055] [Third embodiment] FIG. 3 shows a schematic configuration of a wastewater treatment system according to a third embodiment. This embodiment is different from the second embodiment shown in FIG. 2 in that an adjustment tank 2B is provided in parallel with an adjustment tank 2A ​​(corresponding to the adjustment tank 2 in FIG. 2), and wastewater is returned from the adjustment tank 2B to the adjustment tank 1. This wastewater treatment system also includes a branch pipe 28 that branches off from a relay pipe 27 and connects to the adjustment tank 2B, a return pipe 29 that is connected to the downstream side of the adjustment tank 2B and returns wastewater to the adjustment tank 1, a fifth flow rate measuring unit 9 provided in the branch pipe 28 for measuring the flow rate of wastewater flowing into the adjustment tank 2B, and a sixth flow rate measuring unit 22 provided in the return pipe 29 for measuring the flow rate of wastewater discharged from the adjustment tank 2B. The specifications such as the volumes of the adjustment tanks 2A and 2B are not particularly limited. In FIG. 3, the same parts as those of the second embodiment shown in FIG. 2 are given the same reference numerals, and the description thereof will be omitted.

[0056] The wastewater sent from the adjustment tank 1 by the transfer pump 11 provided in the relay pipe 27 branches and flows into the adjustment tank 2A ​​or 2B. The destination of the water sent from the adjustment tank 1 is switched by controlling the opening and closing of the valve 15 provided downstream of the branch point in the relay pipe 27 and the valve 16 provided in the branch pipe 28. The fourth flow rate measurement unit 8 provided in the relay pipe 27 measures the flow rate of the wastewater flowing into the adjustment tank 2A. The fifth flow rate measurement unit 9 provided in the branch pipe 28 measures the flow rate of the wastewater flowing into the adjustment tank 2B. The fourth flow rate measurement unit 8 and the fifth flow rate measurement unit 9 may be flow meters, or in the case of batch water flow in the adjustment tanks 2A and 2B, they may be units that calculate the flow rate from the amount of increase in the water level per unit time in the adjustment tanks 2A and 2B. In this case, it is necessary to install level gauges in the adjustment tanks 2A and 2B as the fourth flow rate measurement unit 8 and the fifth flow rate measurement unit 9, respectively.

[0057] A transfer pump 13 provided in the wastewater discharge piping 24 sends the wastewater in the adjustment tank 2A ​​to the wastewater treatment equipment 3. A third flow rate measuring unit 10 provided in the wastewater discharge piping 24 measures the flow rate of the wastewater at the outlet of the adjustment tank 2A. Downstream (rear stage) of the third flow rate measuring unit 10, the wastewater sent out from the adjustment tank 2A ​​and the concentrated waste liquid join and mix, and the mixed liquid flows into the wastewater treatment equipment 3 through the wastewater discharge piping 24.

[0058] A transfer pump 14 provided in the return pipe 29 returns the wastewater in the adjustment tank 2B to the adjustment tank 1.

[0059] The sixth flow rate measuring unit 22 provided in the return pipe 29 measures the flow rate of the wastewater returned from the adjustment tank 2B to the adjustment tank 1, and may be measured by a flow meter or may be calculated from the amount of decrease in the water level per unit time in the adjustment tank 2B. In this case, it is necessary to install a level meter in the adjustment tank 2B as the fifth flow rate measuring unit 9.

[0060] In this embodiment, 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.

[0061] In this configuration, the calculation unit 6 first estimates the TOC concentration (estimated value C) of the wastewater in the adjustment tank 2B from the TOC concentration measured by the first pollution load measurement unit 4 upstream of the adjustment tank 1 and the flow rate measured by the fifth flow rate measurement unit 9 using the following estimation method (3)-3.

[0062] 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.

[0063] Next, the calculation unit 6 estimates the TOC concentration at the outlet of the adjustment tank 1 (estimated value D) from the TOC concentration in the adjustment tank 2B obtained as described above (estimated value C), the flow rate measured by the sixth flow rate measurement unit 22, the TOC concentration measured by the first pollution load measurement unit 4 upstream of the adjustment tank 1, and the flow rate measured by the first flow rate measurement unit 5. 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.

[0064] Estimation method (2)-3 From the TOC concentration measured by the first pollution load measuring unit 4 and the flow rate measured by the first flow rate measuring unit 5, the TOC concentration in the adjustment tank 2B (estimated value C), and the flow rate flowing from the adjustment tank 2B to the adjustment tank 1, the change in the wastewater concentration flowing into the adjustment tank 1 is estimated using a perfect mixing tank model, and the TOC concentration (mg / L) at the outlet of the adjustment tank 1 is estimated.

[0065] 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.

[0066] Next, the calculation unit 6 estimates the TOC concentration (estimated value E) at the outlet of the adjustment tank 2A ​​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. When the adjustment tank 2A ​​is a continuous water supply system, the TOC concentration (estimated value E) at the outlet of the adjustment tank 2A ​​is estimated by estimation method (1)-3 or (2)-4, and when the adjustment tank 2A ​​is a batch water supply system, the TOC concentration (estimated value E) at the outlet of the adjustment tank 2A ​​is estimated by estimation method (1)-3 or (2)-4.

[0067] Estimation method (1)-3 The TOC concentration (mg / L) at the outlet of equalization tank 2A ​​is estimated by taking a moving average of the TOC concentration (estimated value D) over a period close to the residence time in equalization tank 2A.

[0068] Estimation method (2)-4 From the TOC concentration (estimated value D) and the flow rate flowing into equalization tank 2A, a perfect mixing tank model is used to estimate the change in the wastewater concentration flowing into equalization tank 2A, and the TOC concentration (mg / L) at the outlet of equalization tank 2A ​​is estimated.

[0069] 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 outlet of equalization tank 2A.

[0070] Using the TOC concentration (estimated value E) at the outlet of the adjustment tank 2A ​​thus obtained, the flow rate measured by the third flow rate measurement unit 10, and the TOC concentration and flow rate of the concentrated wastewater, the wastewater load (kg-TOC / day) is estimated by the above formula 1. In this embodiment, the "adjustment tank outlet" in formula 1 corresponds to the outlet of the adjustment tank 2A.

[0071] The calculation unit 6 judges whether or not it is OK for the mixed liquid to flow into the wastewater treatment equipment 3 based on the estimated wastewater load at the wastewater treatment inlet. The calculation unit 6 controls the start / stop of the transfer pump 20 and the opening / closing of the valve 21, and adjusts the flow rate and inflow timing of the concentrated wastewater sent from the concentrated wastewater tank 17 to the wastewater discharge piping 24 so that the wastewater treatment does not fail. In this case, the concentrated wastewater is sent to the wastewater discharge piping 24 while adjusting the flow rate and flow rate timing so that the estimated wastewater load does not exceed a predetermined value.

[0072] [Fourth embodiment] Fig. 4 shows a schematic configuration of a wastewater treatment system according to a fourth embodiment. This embodiment differs from the first embodiment shown in Fig. 1 in that the concentrated wastewater sent from the concentrated wastewater tank 17 is merged into the adjustment tank 1 instead of the wastewater discharge pipe 24. In Fig. 4, the same parts as those in the first embodiment shown in Fig. 1 are given the same reference numerals and the description thereof will be omitted.

[0073] In this configuration, the thick waste liquid discharge pipe 26 merges the thick waste liquid discharged from the thick waste liquid tank 17 into the adjustment tank 1. In the adjustment tank 1, the wastewater and the thick waste liquid are mixed to form a mixed liquid, and the wastewater discharge pipe 24 allows the mixed liquid discharged from the adjustment tank 1 to flow into the wastewater treatment plant.

[0074] The calculation unit 6 estimates the TOC concentration (originating from raw water) at the 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 "raw water" refers to the liquid in the adjustment tank 1 when no concentrated waste liquid is mixed therein.

[0075] The TOC concentration (originating from raw water) at the outlet of the equalization tank 1 can be estimated using the TOC concentration measured by the pollution load measuring unit 4 (the TOC concentration measured upstream of the equalization tank 1) 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 equalization tank 1 is a continuous or batch-flow tank, for example, different estimation methods can be used, as follows:

[0076] <When water is continuously flowing> Estimation method (1)-4 The TOC concentration (originating from raw water) (mg / L) at the outlet of the equalization tank 1 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 measured upstream of the equalization tank 1 from the present to the previous 50 minutes can be regarded as the TOC concentration (originating from raw water) discharged from the equalization tank 1.

[0077] Estimation method (2)-5 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 TOC concentration of the wastewater flowing into equalization tank 1, and the TOC concentration (derived from raw water) (mg / L) at the outlet of equalization tank 1 is estimated.

[0078] <When passing water through a batch> Estimation method (3)-6 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 (originating from raw water) (mg / L) at the outlet of the equalization tank 1. In order to accurately grasp the total TOC weight and total water volume that flowed into the equalization tank 1, it is desirable to obtain the inlet valve open / close signal of the equalization tank 1 and the pump start / stop signal, and calculate the load by integrating the TOC concentration (originating from raw water) and water volume from the time the inlet valve is "open" to "closed" or while 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 when wastewater is flowing into the equalization tank 1 from the change in the water level in the equalization tank 1.

[0079] The calculation unit 6 estimates the wastewater load (kg-TOC / day) at the wastewater treatment inlet using the TOC concentration (derived from raw water) at the outlet of the adjustment tank 1 estimated by any one of the above estimation methods (1)-4, (2)-5, or (3)-6, the flow rate at the outlet of the adjustment tank 1 measured by the third flow measurement unit 10, the TOC concentration of the concentrated wastewater measured by the second pollution load measurement unit 18, and the flow rate of the concentrated wastewater discharged from the concentrated waste tank measured by the second flow measurement unit 19.

[0080] When the concentrated waste liquid is merged before the third flow rate measuring section 10, the flow rate of the wastewater (mixed liquid) at the outlet of the adjustment tank 1 is the sum of the flow rate from the raw water and the flow rate of the concentrated waste liquid, so the wastewater load is estimated using the following equation 2.

[0081] Equation 2: Wastewater load (kg-TOC / day) = [TOC concentration at the outlet of the equalization tank (originating from raw water) (mg / L) × {flow rate of wastewater (mixed liquid) at the outlet of the equalization tank (m 3 / h)-Flow rate of concentrated waste liquid (m 3 / h)} + TOC concentration of the combined concentrated waste liquid (mg / L) × flow rate of the combined concentrated waste liquid (m 3 / h)] × 24(h) / 1000

[0082] In this embodiment, the concentrated waste liquid is mixed by merging into the adjustment tank 1, but the concentrated waste liquid may be merged downstream of the adjustment tank 1 as long as it is upstream of the third flow rate measurement unit 10. In this case, the wastewater load can be estimated by Equation 2. In this case, it is desirable to consider the residence time from when the concentrated waste liquid merges into the adjustment tank 1 to the point where the wastewater load is calculated for the "TOC concentration of the merged concentrated waste liquid" in Equation 2. For example, if the residence time from when the concentrated waste liquid merges to the point where the wastewater load is calculated is 30 minutes, the average of the TOC concentration measurement results of the second pollution load measurement unit 18 from the present to 30 minutes ago can be estimated as the "TOC concentration of the merged concentrated waste liquid."

[0083] [Fifth embodiment] Fig. 5 shows a schematic configuration of a wastewater treatment system according to a fifth embodiment. This embodiment differs from the second embodiment shown in Fig. 2 in that the concentrated wastewater sent from the concentrated wastewater tank is merged into the adjustment tank 2 instead of the wastewater discharge pipe 24. In Fig. 5, the same parts as those of the second embodiment shown in Fig. 2 are given the same reference numerals and the description thereof will be omitted.

[0084] In this configuration, the thick waste liquid discharge pipe 26 merges the thick waste liquid discharged from the thick waste liquid tank 17 into the adjustment tank 2. In the adjustment tank 2, the wastewater and the thick waste liquid are mixed to form a mixed liquid, and the wastewater discharge pipe 24 allows the mixed liquid discharged from the adjustment tank 2 to flow into the wastewater treatment plant. First, as in the second embodiment, the calculation unit 6 estimates the TOC concentration (estimated value A) at the outlet of the adjustment tank 1 by the above-mentioned estimation method (1)-1 or (2)-1 in the case of continuous water flow, or by the estimation method (3)-1 in the case of batch water flow.

[0085] Next, the TOC concentration (originating from raw water) (estimated value B) at the 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 fourth flow rate 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)-5 or (2)-6 is used to estimate the TOC concentration (originating from raw water) (estimated value B) at the outlet of the adjustment tank 2, while in the case of batch water supply, estimation method (3)-7 is used.

[0086] Estimation method (1)-5 The TOC concentration (derived from raw water) (mg / L) at the outlet of equalization tank 2 is estimated by taking a moving average of the TOC concentration (estimated value A) over a period close to the residence time in equalization tank 2.

[0087] Estimation method (2)-6 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 (derived from raw water) (mg / L) at the outlet of equalization tank 2 is estimated.

[0088] Estimation method (3)-7 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 (derived from raw water) (mg / L) at the outlet of adjustment tank 2.

[0089] The wastewater load (kg-TOC / day) is estimated using the TOC concentration (originating from raw water) (estimated value B) at the outlet of the adjustment tank 2 thus obtained, the flow rate of the wastewater at the outlet of the adjustment tank 2 measured by the third flow rate measuring unit 10, and the TOC concentration and flow rate of the concentrated wastewater. When the concentrated wastewater is merged before the third flow rate measuring unit 10, the flow rate of the wastewater (mixed liquid) at the outlet of the adjustment tank 2 is the sum of the flow rate originating from the raw water and the flow rate of the concentrated wastewater, so the wastewater load is estimated using the above formula 2.

[0090] In this embodiment, the concentrated waste liquid is mixed by merging it into the adjustment tank 2, but the concentrated waste liquid may be merged at any position downstream of the adjustment tank 1 as long as it is upstream of the third flow rate measuring unit 10. In this case, the wastewater load can also be estimated by Equation 2.

[0091] In the above first to fifth embodiments, a configuration has been described in which the calculation unit 6 performs calculations such as estimating the pollution load at the outlet of the adjustment tank and estimating the wastewater load at the inlet of the wastewater treatment plant. However, the calculation unit 6 may be configured as a single computer, or may perform distributed processing using multiple computers.

[0092] 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]

[0093] 1,2,2A,2B Adjustment tank 3 Wastewater treatment facilities 4. First Pollutant Load Measurement Section 5 1st flow rate measuring section 6 Arithmetic section 8 4th flow measurement section 9 5th flow measurement section 10 Third flow measurement section 11, 13, 14, 20 Transfer pump 17 Thick waste liquid tank 18. Second Pollutant Load Measurement Section 19 2nd flow rate measurement section 22 6th flow measurement section 23 Drainage inflow piping 24 Drainage discharge piping 25 Thick waste liquid inlet piping 26 Thick waste liquid discharge piping 27 Relay piping 28 Branch piping 29 Return piping

Claims

1. A method for estimating a wastewater load at a wastewater treatment inlet of a wastewater treatment facility that treats a mixed liquid of wastewater and concentrated wastewater, comprising: Measure the primary pollution load of the wastewater, Estimating a pollution load originating from the wastewater at a confluence of the wastewater and the concentrated wastewater or a predetermined position downstream thereof based on the first pollution load; Measure the secondary pollution load of the concentrated wastewater, Estimating a pollution load of the concentrated liquid waste at the confluence or the predetermined position based on the second pollution load; A method for estimating a wastewater load, comprising estimating the wastewater load based on an estimated value of a pollution load originating from wastewater at the confluence or the specified location and an estimated value of a pollution load of concentrated liquid waste.

2. The wastewater is sent to the wastewater treatment facility via an adjustment tank, The confluence is located downstream of the adjustment tank, The method for estimating a wastewater load according to claim 1 , wherein the first pollution load is measured upstream of the adjustment tank.

3. Measure a first flow rate of wastewater flowing into the adjustment tank; The method for estimating a wastewater load according to claim 2 , further comprising estimating a pollution load of the wastewater at the confluence by using the first pollution load and the first flow rate.

4. The thick waste liquid is sent from the thick waste liquid tank to the junction, The second pollution load is measured in the concentrated waste liquid tank; measuring a second flow rate of the concentrated liquid waste discharged from the concentrated liquid waste tank; The method for estimating a wastewater load according to claim 1, further comprising estimating a pollution load of the concentrated wastewater at the confluence from the second pollution load and the second flow rate, taking into account a residence time from the concentrated wastewater tank to the confluence.

5. A method for wastewater treatment, comprising the steps of: not sending the concentrated wastewater to the junction when the wastewater load estimated by the method according to claim 1 is equal to or greater than a predetermined value.

6. The wastewater treatment method according to claim 5 , wherein, when the estimated wastewater load is less than a predetermined value, the concentrated wastewater is fed to the junction at a flow rate not exceeding the predetermined value.

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