Method for estimating drainage load and drainage treatment method

Abstract

Provided are: a method for estimating drainage load whereby a water quality item or an operation management item of drainage can be stably measured by preventing the adhesion of slime to a drainage contact-type instrument; and a drainage treatment method capable of stably performing drainage treatment. A method for estimating drainage load in a drainage treatment facility in which drainage from a single system or a plurality of systems flows into a regulation tank and is sent out from the regulation tank. A water quality item or an operation management item is measured or estimated by a drainage contact-type instrument on the upstream side of the regulation tank and, in the case of a plurality of systems, on the downstream side of a merging part of drainage from each of the systems, and drainage load is estimated on the basis of the measured value or the estimated value.

Description

Method for estimating drainage load and drainage treatment method

[0001] The present invention relates to a method for continuously or periodically measuring, before a regulating tank, a pollution load of drainage or an item correlated with the pollution load, and estimating a drainage load at an inflow section of drainage treatment, and a drainage treatment method for stabilizing drainage treatment by adjusting an inflow amount to drainage treatment or distributing high-load drainage based on the estimated drainage load.

[0002] Drainage discharged from manufacturing plants such as beverage and food plants often varies greatly in concentration and drainage volume depending on the manufactured items, manufacturing volume, cleaning elapsed time of the production line, etc. In many cases, the operating conditions of drainage treatment suitable for the drainage load are different, and when the drainage load fluctuation is large, it may affect the treatment situation.

[0003] Particularly, organic drainage is generally subjected to biological treatment such as aerobic treatment or anaerobic treatment as drainage treatment. However, if the drainage load is large, there is a risk that biological treatment will fail exceeding the treatment capacity of organisms, and problems such as deterioration of treated water quality may occur.

[0004] Also, in treatment by physicochemical treatment such as treatment by Fenton reaction or adsorption, since the required amounts of chemicals and adsorbents to be added change, it is important to grasp the fluctuation of the drainage load flowing into the treatment equipment.

[0005] Conventionally, operators periodically collect and analyze drainage to grasp the drainage load at the inflow section of drainage treatment. When high-load drainage flows in, countermeasures such as emergency evacuation to another tank, dilution, and reduction of the inflow amount to drainage treatment are manually taken. However, with this method, continuous measurement cannot be performed because it is always done manually by humans, and drainage treatment may fail and the treated water quality may deteriorate due to missing the inflow of high-load drainage or delay in countermeasures. Therefore, it is very important to continuously grasp the load of the inflowing drainage and take countermeasures promptly so that the drainage treatment does not fail.

[0006] Patent Document 1 evaluates the wastewater load at the wastewater treatment inlet by measuring COD (Chemical Oxygen Demand) or TOC (Total Organic Carbon) and flow rate near the inlet of the biological treatment. However, measuring near the inlet of the biological treatment presents challenges in achieving stable measurements due to slime adhesion to the instrument.

[0007] It is generally known that conditions for slime formation include a pH of 4-9, a water temperature of 15-35°C, and a BOD (Biochemical Oxygen Demand) concentration of 30 mg / L or higher. The raw water for wastewater treatment is stabilized in a tank (hereinafter referred to as the adjustment tank) located before the wastewater treatment process, making it more susceptible to the above conditions that facilitate the formation of slime, such as microorganisms. This tendency is particularly pronounced when the subsequent wastewater treatment is biological treatment, and there is a concern that accurate measurements may not be possible when measuring wastewater in the adjustment tank or downstream from the adjustment tank with instruments due to slime adhesion to the instruments or blockage of the sampling tubes. In addition, when measuring in the adjustment tank or downstream from the adjustment tank, considering the time lag between starting measurement with an instrument and obtaining the results, even if it is possible to detect that the wastewater in the tank has become high-load, countermeasures may be delayed, high-load operation of the downstream stage may continue because the load in the tank is already high, or dilution may be necessary.

[0008] Japanese Patent Publication No. 2013-138976

[0009] This invention has been made in view of the above-mentioned conventional circumstances, and aims to provide a method for estimating wastewater load that can stably measure wastewater pollution load or items correlated with pollution load while preventing slime from adhering to instruments, and a wastewater treatment method that can stably perform wastewater treatment.

[0010] As a result of diligent research, the inventors have found that when wastewater containing sterilizing components such as acid / alkaline washing wastewater and oxidizing agents, which can suppress slime generation (for example, water temperature of 40°C or higher, pH of 4 or lower, pH of 9 or higher, or ORP of 750 mV or higher), flows in for a certain period of time or longer (for example, 20% or more of the total wastewater inflow time), microorganisms are less likely to continuously proliferate, and slime generation is suppressed. Therefore, in cases of such fluctuations in wastewater quality, measuring with a wastewater contact-type instrument upstream of the adjustment tank, rather than in the adjustment tank or downstream of the adjustment tank, can reduce the risk of slime adhesion to the instrument, thereby achieving the above objective. Regarding such fluctuations in wastewater quality, for example, when flowing in from a single line, the water quality conditions that can suppress slime generation may be met at different times of the day due to differences in the products manufactured in the line or the cleaning process of the manufacturing line. When water flows in from multiple lines, water quality fluctuations due to differences in the products manufactured in a particular line or cleaning processes in the manufacturing line may cause the wastewater from that line to meet the conditions for slime suppression at certain times of the day. In addition, when wastewater from another line with different water quality flows in, the incoming wastewater from that line or the mixed wastewater from multiple lines may meet the conditions for slime generation suppression. The present invention is based on this knowledge.

[0011] [1] A method for estimating the wastewater load of a wastewater treatment facility in which wastewater from one or more lines flows into a regulating tank and wastewater is sent from the regulating tank, wherein the wastewater flowing into the regulating tank has a water quality that can suppress slime generation for at least a certain period of time, and a wastewater contact instrument is used to measure or estimate water quality items or operational management items upstream of the regulating tank, and downstream of the confluence of wastewater from each line in the case of multiple lines, and the wastewater load is estimated based on the measured or estimated values.

[0012] [2] The water quality that can suppress the generation of slime is the method for estimating wastewater load described in [1], which satisfies at least one of the following conditions: water temperature of 40°C or higher, pH of 4 or lower, pH of 9 or higher, and ORP of 750 mV or higher.

[0013] [3] The wastewater load estimation method according to [1] or [2], wherein the water quality items or operational management items measured by the wastewater contact instrument are the pollution load or items correlated with the pollution load, and the first flow rate of wastewater flowing into the adjustment tank is measured, and the pollution load or items correlated with the pollution load at the wastewater inlet to the wastewater treatment facility (wastewater treatment inlet) is estimated using the measured pollution load or items correlated with the pollution load and the first flow rate.

[0014] [4] The method for estimating wastewater load according to [3], wherein a second flow rate of wastewater flowing into the wastewater treatment facility is measured, and the wastewater load of the wastewater treatment inlet is estimated using the estimated pollution load of the wastewater treatment inlet or an item correlated with the pollution load and the second flow rate.

[0015] [5] A wastewater treatment method comprising switching the destination of wastewater flowing into the adjustment tank from the adjustment tank to a high-load adjustment tank when the wastewater load estimated by the method in [4] is greater than or equal to a predetermined value.

[0016] [6] The wastewater treatment method according to [5], wherein, after switching the inflow destination of the wastewater from the adjustment tank to the high load adjustment tank, if the estimated wastewater load falls below a predetermined value, the wastewater in the high load adjustment tank is sent to the wastewater treatment facility.

[0017] [7] The wastewater treatment method according to [5], wherein, after switching the inflow destination of the wastewater from the adjustment tank to the high load adjustment tank, if the estimated wastewater load falls below a predetermined value, the wastewater in the high load adjustment tank is sent to the adjustment tank.

[0018] [8] The wastewater treatment method according to [5], wherein the adjustment tank into which the wastewater flows is arranged in parallel in multiple stages, and water is sent from the adjustment tank to the wastewater treatment facility at a flow rate such that the estimated wastewater load does not exceed a predetermined value.

[0019] According to the present invention, water quality parameters such as wastewater pollution load or parameters correlated with pollution load, or operational management parameters, can be measured stably while preventing slime from adhering to the instruments. Furthermore, according to the present invention, wastewater treatment can be performed stably.

[0020] This is a schematic diagram of a wastewater treatment system according to an embodiment of the present invention. This is a schematic diagram of a wastewater treatment system according to the same embodiment

[0021] Embodiments of the present invention will now be described based on the drawings. As shown in Figure 1, the wastewater treatment system according to an embodiment of the present invention comprises a regulating tank 1, a wastewater treatment facility 3 installed downstream of the regulating tank 1, a pollution load measuring unit 4 provided upstream of the regulating tank 1, a first flow rate measuring unit 5 for measuring the flow rate of wastewater flowing into the regulating tank 1, a second flow rate measuring unit 10 for measuring the flow rate of wastewater flowing into the wastewater treatment facility 3, and a calculation unit 6 for estimating the wastewater load at the inlet of the wastewater treatment facility 3 (outlet of the regulating tank 1). The calculation unit 6 is, for example, a computer.

[0022] Adjustment tank 1 receives wastewater from a single line, or wastewater from multiple lines that merge simultaneously or at different times. The wastewater flowing into adjustment tank 1 is of a quality that can suppress slime generation, such as acid / alkaline wash wastewater or water containing sterilizing components such as oxidizing agents (for example, water quality that satisfies at least one of the following conditions: water temperature of 40°C or higher, pH of 4 or lower, pH of 9 or higher, and ORP (oxidation-reduction potential) of 750 mV or higher), and this wastewater is present for a certain period of time or longer (for example, accounting for 20% or more of the total wastewater inflow time).

[0023] The 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 of measuring TOC concentration as the pollution load is described, but the measurement items are not limited to TOC concentration and may be other indicators of pollution load such as COD concentration or SS. Furthermore, the pollution load to be measured may include items correlated with the pollution load, such as electrical conductivity or Brix sugar content.

[0024] The pollution load measuring unit 4 measures the pollution load (TOC concentration) by immersing the instrument in the wastewater upstream of the adjustment tank 1, and downstream of the confluence of wastewater from each series if there are multiple series.

[0025] One or more adjustment tanks 1 are provided, and multiple adjustment tanks 1 may be arranged in parallel as described below. The specifications of the adjustment tank 1, such as its volume, are not particularly limited. An adjustment tank 1 is defined as having an HRT (hydraulic residence time) of 30 minutes or more, for the purpose of adjusting and mitigating fluctuations in water quality and volume.

[0026] The first flow rate measuring unit 5, which measures the flow rate of wastewater flowing into the adjustment tank 1, may be a flow meter, or if the adjustment tank 1 is being flowed in batches, it may be calculated from the amount of water level increase per unit time in the adjustment tank 1. Alternatively, if the adjustment tank 1 is being flowed continuously, the flow rate of wastewater flowing into the adjustment tank 1 may be calculated from the sum of the change in the amount of water stored in the adjustment tank 1 and the discharge flow rate from the adjustment tank.

[0027] The wastewater treatment facility 3 performs treatment to remove dirt, oil, and other substances contained in the wastewater. The wastewater treatment method and the number of systems are not particularly limited. Examples of treatment methods include so-called biological treatment, including aerobic and anaerobic treatments, and physicochemical treatments such as Fenton treatment and activated carbon treatment.

[0028] The second flow rate measuring unit 10, which measures the flow rate of wastewater flowing into the wastewater treatment facility 3, may be a flow meter, or if the adjustment tank 1 is being treated in batches, it may be calculated from the amount of water level decrease per unit time in the adjustment tank 1.

[0029] The calculation unit 6 estimates the TOC concentration at the inlet of the wastewater treatment facility 3 (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) supplied to the wastewater treatment facility 3 using the estimated TOC concentration and the flow rate measured by the second flow rate measurement unit 10.

[0030] The method for estimating the TOC concentration at the inlet of the wastewater treatment facility 3 (hereinafter also referred to as the "wastewater treatment inlet") 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 can be carried out using various proposed concentration calculation models for stagnant water tanks. However, depending on whether the adjustment tank 1 is continuously flowing or batch flowing, for example, the following different estimation methods can be used.

[0031] <During continuous water flow> Estimation method (1)-1 The TOC concentration (mg / L) at the wastewater treatment inlet is estimated by moving the TOC concentration measured upstream of the adjustment tank 1 over a period of time close to the residence time in the adjustment tank 1. For example, if the residence time in the adjustment tank 1 is 50 minutes, the average of the TOC concentration measurement results from the present to 50 minutes ago can be considered as the TOC concentration at the wastewater treatment inlet (discharged from the adjustment tank 1).

[0032] Estimation Method (2)-1 Using the TOC concentration and flow rate measured upstream of the adjustment tank 1, the change in wastewater concentration flowing into the adjustment tank 1 is estimated using a complete mixing tank model, and the TOC concentration (mg / L) at the wastewater treatment inlet is estimated.

[0033] <During batch water flow> Estimation method (3)-1 Total TOC weight (g) that flows into adjustment tank 1 = Total water volume (m³) that flows into adjustment tank 1 ３ The TOC concentration (mg / L) at the wastewater treatment inlet is estimated by dividing by ). In order to accurately determine the total weight of TOC and the total volume of water that flows into the adjustment tank 1, it is desirable to obtain the opening / closing signal of the adjustment tank inlet valve and the start / stop signal of the pump, and calculate the load by accumulating the TOC concentration and volume of water from the time the inlet valve is "open" to "closed", or during the time the pump is operating. If it is difficult to obtain the opening / closing signal of the valve or the start / stop signal of the pump, the timing of wastewater flow into the adjustment tank 1 can be determined from the change in the water level of the adjustment tank 1.

[0034] The calculation unit 6 estimates the wastewater load (kg-TOC / day) using the following formula 1, based on 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 measuring unit 10.

[0035] Equation 1: Wastewater load (kg - TOC / day) = TOC concentration at wastewater treatment inlet (mg / L) × Flow rate at wastewater treatment inlet (m³) ３ / h)×24h / 1000

[0036] As shown in Figure 2, if a regulating tank 2 is installed in series with regulating tank 1 between regulating tank 1 and wastewater treatment equipment 3, first the TOC concentration (estimated value A) at the outlet of regulating tank 1 is estimated. One or more regulating tanks 2 are provided, and multiple regulating tanks 2 may be arranged in parallel as described later. The specifications of regulating tank 2, such as its volume, are not particularly limited. Similar to Figure 1, the estimation method differs depending on whether regulating tank 1 is continuously flowing or batch flowing. In the case of continuous flow, the TOC concentration (estimated value A) at the outlet of regulating tank 1 is estimated using estimation method (1)-1 or (2)-1 above, and in the case of batch flow, estimation method (3)-1 is used.

[0037] Next, the TOC concentration at the wastewater treatment inlet (outlet of adjustment tank 2) (estimated value B) is estimated from the TOC concentration at the outlet of adjustment tank 1 (estimated value A) obtained as described above and the flow rate of wastewater flowing into adjustment tank 2 measured by the third flow rate measuring unit 8. Here again, the estimation method differs depending on whether adjustment tank 2 is continuously flowing or batch flowing. In the case of continuous flow, estimation method (1)-2 or (2)-2 is used to estimate the TOC concentration at the wastewater treatment inlet (estimated value B), and in the case of batch flow, estimation method (3)-2 is used.

[0038] Estimation Method (1)-2 The TOC concentration (mg / L) at the wastewater treatment inlet is estimated by moving the TOC concentration (estimated value A) over a time close to the residence time in the adjustment tank 2.

[0039] Estimation Method (2)-2 Using the TOC concentration (estimated value A) and the flow rate into the adjustment tank 2, the change in the wastewater concentration flowing into the adjustment tank 2 is estimated using a complete mixing tank model, and the TOC concentration (mg / L) at the wastewater treatment inlet is estimated.

[0040] Estimation method (3)-2. Divide the total TOC weight (g) flowing into the adjustment tank 2 by the total amount of water (m ３ ) flowing into the adjustment tank 2 to estimate the TOC concentration (mg / L) of the wastewater treatment inflow section.

[0041] The third flow rate measurement unit 8 that measures the flow rate of the wastewater flowing into the adjustment tank 2 may be a flow meter, or may be calculated from the increase in the water level per unit time in the adjustment tank 2 when the adjustment tank 2 is in batch water flow. Or when the adjustment tank 2 is in continuous water flow, 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 1.

[0042] From the TOC concentration (estimated value B) of the wastewater treatment inflow section obtained in this way and the flow rate of the wastewater treatment inflow section measured by the second flow rate measurement unit 10, the wastewater load (kg-TOC / day) is estimated by the above formula 1.

[0043] Next, as shown in FIG. 3, consider the case where adjustment tanks 2A and 2B are provided in parallel between the adjustment tank 1 and the wastewater treatment facility 3, and wastewater is returned from the adjustment tank 2B to the adjustment tank 1. The wastewater flowing out of the adjustment tank 1 flows into the adjustment tank 2A or 2B. The wastewater flowing out of the adjustment tank 2A flows into the wastewater treatment facility 3. The wastewater flowing out of the adjustment tank 2B is returned to the adjustment tank 1.

[0044] The fourth flow rate measurement unit 13 measures the flow rate of the wastewater flowing into the adjustment tank 2B, and may be measured by a flow meter or may be calculated from the increase in the water level per unit time in the adjustment tank 2B. The fifth flow rate measurement unit 15 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 decrease in the water level per unit time in the adjustment tank 2B.

[0045] In this case, the condition is that the adjustment tank 2B that returns the wastewater to the adjustment tank 1 is in batch water flow, and the adjustment tank 1 and the adjustment tank 2A may be either in continuous water flow or batch water flow. One or more adjustment tanks 2A are provided, and a plurality of adjustment tanks 2A may be arranged in parallel.

[0046] First, the TOC concentration (estimated value C) of the wastewater in the adjustment tank 2B is estimated using the following estimation method (3)-3, based on the TOC concentration measured upstream of the adjustment tank 1 and the flow rate measured by the fourth flow rate measuring unit 13.

[0047] Estimation Method (3)-3 Total TOC weight (g) that flowed into adjustment tank 2B = Total water volume (m³) that flowed into adjustment tank 2B ３ The TOC concentration (mg / L) in the adjustment tank 2B is estimated by dividing by ).

[0048] Next, the TOC concentration at the outlet of the adjustment tank 1 (estimated value D) is estimated from the TOC concentration (estimated value C) of the adjustment tank 2B obtained as described above, the flow rate measured by the fifth flow rate measuring unit 15, and the TOC concentration and flow rate measured on the upstream side of the adjustment tank 1. If the adjustment tank 1 is continuously flowing, the estimation is performed using estimation method (2)-3; if the adjustment tank 1 is batch flowing, the estimation is performed using estimation method (3)-4.

[0049] Estimation Method (2)-3 Using the TOC concentration and flow rate measured upstream of adjustment tank 1, the TOC concentration in adjustment tank 2B (estimated value C), and the flow rate from adjustment tank 2B to adjustment tank 1, the change in the wastewater concentration flowing into adjustment tank 1 is estimated using a complete mixing tank model, and the TOC concentration (mg / L) at the outlet of adjustment tank 1 is estimated.

[0050] Estimation Method (3)-4 Total TOC weight (g) that flowed into adjustment tank 1 is equal to the total water volume (m³) that flowed into adjustment tank 1. ３ The TOC concentration (mg / L) at the outlet of adjustment tank 1 is estimated by dividing by ). The total TOC weight and total water volume are calculated by adding the TOC weight and water volume measured upstream of adjustment tank 1 to the TOC weight and water volume returned from adjustment tank 2B, respectively.

[0051] Next, the TOC concentration at the wastewater treatment inlet (outlet of adjustment tank 2A) (estimated value E) is estimated from the TOC concentration at the outlet of adjustment tank 1 (estimated value D) obtained as described above and the flow rate into adjustment tank 2A. If adjustment tank 2A ​​is continuously flowing, the TOC concentration at the wastewater treatment inlet (estimated value E) is estimated using estimation method (1)-3 or (2)-4; if batch flow is used, estimation method (3)-5 is used.

[0052] Estimation Method (1)-3 The TOC concentration (mg / L) at the wastewater treatment inlet is estimated by moving the TOC concentration (estimated value D) over a time close to the residence time in the adjustment tank 2A.

[0053] Estimation Method (2)-4 Using the TOC concentration (estimated value D) and the flow rate into the adjustment tank 2A, the change in the wastewater concentration flowing into the adjustment tank 2A ​​is estimated using a complete mixing tank model, and the TOC concentration (mg / L) at the wastewater treatment inlet is estimated.

[0054] Estimation Method (3)-5 Total TOC weight (g) that flowed into adjustment tank 2A ​​= Total water volume (m³) that flowed into adjustment tank 2A ３ The TOC concentration (mg / L) at the wastewater treatment inlet is estimated by dividing by ).

[0055] The wastewater load (kg-TOC / day) is estimated using Equation 1 above, based on 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.

[0056] According to this embodiment, since the pollution load (or items correlated with the pollution load) is measured upstream of the adjustment tank 1, where pH, water temperature, and water quality fluctuate significantly and slime generation is less likely, the pollution load can be measured stably and accurately. Furthermore, the wastewater load at the wastewater treatment inlet can be estimated from the measured pollution load and flow rate, and the inflow of high-load wastewater can be quickly detected from this estimated value. Based on the estimated wastewater load, the amount of wastewater flowing into the wastewater treatment system can be controlled or high-load wastewater can be diverted to a high-load adjustment tank to prevent wastewater treatment from failing, thereby stabilizing the wastewater treatment system.

[0057] Figure 4 shows a configuration in which a high-load adjustment tank 12 is provided with the wastewater treatment system shown in Figure 1. In the configuration shown in Figure 4, the high-load adjustment tank 12 is arranged in parallel with the adjustment tank 1. By controlling the opening and closing of valves 17A and 17B, it is possible to switch whether the wastewater supplied by the transfer pump 11 flows into the adjustment tank 1 or the high-load adjustment tank 12.

[0058] 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 of the wastewater treatment inlet using one of the estimation methods (1)-1, (2)-1, or (3)-1 described above. The calculation unit 6 also uses the estimated TOC concentration and the flow rate measured by the second flow rate measurement unit 10 to estimate the wastewater load of the wastewater treatment inlet and determines whether it is safe for the wastewater to flow into the wastewater treatment facility 3.

[0059] If the calculation unit 6 determines that the wastewater load is high and that wastewater treatment may fail, it closes valve 17A and opens valve 17B, allowing the wastewater to flow into the high-load adjustment tank 12. Even after switching the wastewater inlet to the high-load adjustment tank 12, the transfer pump 20 continues to send wastewater from the adjustment tank 1 to the wastewater treatment facility 3, and the calculation unit 6 continues to estimate the TOC concentration at the wastewater treatment inlet and the wastewater load.

[0060] Subsequently, when the estimated wastewater load decreases, the wastewater inflow destination is switched from the high-load adjustment tank 12 to the adjustment tank 1. The calculation unit 6 also controls the transfer pump 19 to send wastewater from the high-load adjustment tank 12 to the wastewater treatment facility 3. The wastewater from the high-load adjustment tank 12 is mixed with the wastewater from the adjustment tank 1 and flows into the wastewater treatment facility 3. It is preferable to control the transfer pump 19 to adjust the flow rate of wastewater sent from the high-load adjustment tank 12 so that the wastewater treatment does not fail.

[0061] The calculation unit 6 may display the opening and closing timing of valves 17A and 17B on a monitor screen or the like, and the operator may manually control the opening and closing of valves 17A and 17B according to 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, and the operator may manually operate the pumps according to the display. Alternatively, instead of transfer pumps 19 and 20, a transfer pump may be installed downstream of the confluence point, and switching valves may be provided before the confluence of the drainage from the adjustment tank 1 and the high-load adjustment tank, so that the system can be operated with a single transfer pump.

[0062] In the configuration shown in Figure 4, the wastewater in the high-load adjustment tank 12 is sent to the wastewater treatment facility 3 when the wastewater load decreases. However, as shown in Figure 5, the wastewater in the high-load adjustment tank 12 may also be sent to the adjustment tank 1.

[0063] In the configuration shown in Figure 6, wastewater is arbitrarily sent to adjustment tank 1 and adjustment tank 1' without considering the wastewater pollution load. When sending wastewater to adjustment tank 1, valve 17A is opened and valve 17B is closed, and when sending wastewater to adjustment tank 1', valve 17A is closed and valve 17B is opened. In addition, wastewater is sent to the wastewater treatment facility 3 from the adjustment tank that is not receiving wastewater from adjustment tanks 1 and 1'. If the calculation unit 6 determines that the wastewater load is high and that wastewater treatment may fail, it controls the transfer pumps 19' and 20' to adjust the flow rate of wastewater sent from adjustment tanks 1 and 1' so that the wastewater load (TOC concentration × flow rate) does not cause wastewater treatment to fail. The calculation unit 6 may display the amount of water being sent by the transfer pumps 19' and 20' on a monitor screen or the like, and an operator may manually operate the pumps according to the display. Alternatively, instead of transfer pumps 19' and 20', a transfer pump may be installed downstream of the confluence point, and switching valves may be provided just before the wastewater from adjustment tank 1 and adjustment tank 1' merge, so that the operation can be carried out with a single transfer pump.

[0064] 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 supplied from the adjustment tank 1 flows into the adjustment tank 2 or the high-load adjustment tank 12.

[0065] 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 estimation methods (1)-1, (2)-1, or (3)-1 described above.

[0066] The calculation unit 6 uses the estimated TOC concentration at the outlet of the adjustment tank 1 and the flow rate of wastewater flowing into the adjustment tank 2 measured by the third flow rate measuring unit 8 to estimate the TOC concentration at the wastewater treatment inlet (outlet of adjustment tank 2) using one of the estimation methods (1)-2, (2)-2, or (3)-2 described above. The calculation unit 6 also uses the estimated TOC concentration at the wastewater treatment inlet and the flow rate of wastewater treatment inlet measured by the second flow rate measuring unit 10 to estimate the wastewater load at the wastewater treatment inlet using equation 1 described above.

[0067] If the calculation unit 6 determines that the wastewater load is high (the wastewater load is above a predetermined value) and that wastewater treatment may fail, it closes valve 7A and opens valve 7B, allowing the wastewater sent from the adjustment tank 1 to flow into the high-load adjustment tank 12. Even after switching the destination of the wastewater to the high-load adjustment tank 12, the transfer pump 20 continues to send wastewater from the adjustment tank 2 to the wastewater treatment facility 3, and the calculation unit 6 continues to estimate the TOC concentration at the outlet of the adjustment tank 1, the TOC concentration at the wastewater treatment inlet, and the wastewater load.

[0068] Subsequently, when the estimated drainage load decreases (when the drainage load falls below a predetermined value), the drainage inlet is switched from the high-load adjustment tank 12 to the adjustment tank 2. The calculation unit 6 controls the transfer pump 19 to send drainage from the high-load adjustment tank 12 to the drainage treatment facility 3. The drainage from the high-load adjustment tank 12 is mixed with the drainage from the adjustment tank 2 and flows into the drainage treatment facility 3. It is preferable to control the transfer pump 19 to adjust the flow rate of drainage sent from the high-load adjustment tank 12 to the drainage treatment facility 3 so that the drainage treatment does not fail.

[0069] In the configuration shown in Figure 7, the opening and closing of valves 7A and 7B were controlled to switch the destination of the wastewater supplied from the adjustment tank 1. However, as shown in Figure 8, a transfer pump 18A that supplies water from adjustment tank 1 to adjustment tank 2 and a transfer pump 18B that supplies water from adjustment tank 1 to high-load adjustment tank 12 may be provided, and the starting and stopping of the transfer pumps 18A and 18B may be controlled to switch whether the wastewater flows into adjustment tank 2 or high-load adjustment tank 12. The calculation unit 6 may display the timing of starting and stopping the transfer pumps 18A and 18B on a monitor screen or the like, and an operator may manually operate the pumps according to the display.

[0070] In the configuration shown in Figure 7, the wastewater in the high-load adjustment tank 12 is sent to the wastewater treatment facility 3 when the wastewater load decreases. However, as shown in Figure 9, the wastewater in the high-load adjustment tank 12 may also be sent to the adjustment tank 2.

[0071] In the configuration shown in Figure 9, the opening and closing of valves 7A and 7B was controlled to switch the destination of the wastewater supplied from the adjustment tank 1. However, as shown in Figure 10, a transfer pump 18A that supplies water from adjustment tank 1 to adjustment tank 2 and a transfer pump 18B that supplies water from adjustment tank 1 to high-load adjustment tank 12 may be provided, and the starting and stopping of the 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.

[0072] In the configuration shown in Figure 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, and when sending wastewater to adjustment tank 2', valve 7A is closed and valve 7B is opened. In addition, wastewater is sent to the wastewater treatment facility 3 from the adjustment tank that is not receiving wastewater from adjustment tank 2 or adjustment tank 2'. Alternatively, as shown in Figure 12, 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 adjustment tank 2' may be provided, and the starting and stopping of the pumps may be controlled separately. If the calculation unit 6 determines that the wastewater load is high and that wastewater treatment may fail, it controls the 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) does not cause wastewater treatment to fail.

[0073] Figure 13 shows a configuration in which the adjustment tanks 2A and 2B of the wastewater treatment system shown in Figure 3 are replaced with adjustment tank 2 and 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 supplied from adjustment tank 1 flows into adjustment tank 2 or high-load adjustment tank 12.

[0074] The calculation unit 6 obtains the TOC concentration measured by the pollution load measurement unit 4 and the flow rate of wastewater flowing into the high-load adjustment tank 12 measured by the fourth flow rate measurement unit 13, and estimates the TOC concentration of the high-load adjustment tank 12 in the same manner as the estimation method (3)-3 described above.

[0075] 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 measuring unit 15, the TOC concentration measured by the pollution load measuring unit 4, and the flow rate measured by the first flow rate measuring unit 5 to estimate the TOC concentration at the outlet of the adjustment tank 1 using the estimation method (2)-3 or (3)-4 described above.

[0076] Next, the calculation unit 6 uses the estimated TOC concentration at the outlet of the adjustment tank 1 and the flow rate of wastewater flowing into the adjustment tank 2 measured by the third flow rate measuring unit 8 to estimate the TOC concentration at the wastewater treatment inlet (outlet of the adjustment tank 2) in the same manner as any of the estimation methods (1)-3, (2)-4, or (3)-5 described above.

[0077] Then, the calculation unit 6 estimates the wastewater load using the above formula 1, based on 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.

[0078] If the calculation unit 6 determines that the wastewater load is high and that wastewater treatment may fail, it closes valve 7A and opens valve 7B, allowing the wastewater sent from the adjustment tank 1 to flow into the high-load adjustment tank 12. Even after switching the destination of the wastewater to the high-load adjustment tank 12, the transfer pump 20 continues to send wastewater from the adjustment tank 2 to the wastewater treatment facility 3, and the calculation unit 6 continues to estimate the wastewater load.

[0079] Subsequently, when the drainage load decreases, the drainage inlet is switched from the high-load adjustment tank 12 to the adjustment tank 2. The calculation unit 6 controls the transfer pump 19 to return the drainage from the high-load adjustment tank 12 to the adjustment tank 1.

[0080] In the configuration shown in Figure 13, the opening and closing of valves 7A and 7B was controlled to switch the destination of the wastewater supplied from the adjustment tank 1. However, as shown in Figure 14, a transfer pump 18A that supplies water from adjustment tank 1 to adjustment tank 2 and a transfer pump 18B that supplies water from adjustment tank 1 to high-load adjustment tank 12 may be provided, and the starting and stopping of the 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.

[0081] In the above embodiment, a configuration was described in which the calculation unit 6 performs calculations such as estimating the pollution load at the wastewater treatment inlet and estimating the wastewater load at the wastewater treatment inlet. However, the calculation unit 6 may consist of a single computer, or it may be a distributed processing system using multiple computers.

[0082] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined.

[0083] 1, 2, 2' Adjustment tank 3 Wastewater treatment equipment 4 Pollution load measurement unit 5 First flow rate measurement unit 6 Calculation unit 8 Third flow rate measurement unit 10 Second flow rate measurement unit 11, 19, 19', 20, 20' Transfer pump 12 High load adjustment tank 13 Fourth flow rate measurement unit 15 Fifth flow rate measurement unit

Claims

1. A method for estimating the wastewater load of a wastewater treatment facility in which wastewater from one or more lines flows into a regulating tank and wastewater is sent from the regulating tank, wherein the wastewater flowing into the regulating tank has a water quality that can suppress slime generation for at least a certain period of time, and water quality items or operational management items are measured or estimated using a wastewater contact instrument upstream of the regulating tank, and downstream of the confluence of wastewater from each line in the case of multiple lines, and the wastewater load is estimated based on the measured or estimated values.

2. The method for estimating wastewater load according to claim 1, wherein the water quality that can suppress the generation of slime satisfies at least one of the following conditions: water temperature of 40°C or higher, pH of 4 or lower, pH of 9 or higher, and ORP of 750 mV or higher.

3. The method for estimating wastewater load according to claim 1 or 2, wherein the water quality items or operational management items measured by the wastewater contact instrument are the pollution load or items correlated with the pollution load, the first flow rate of wastewater flowing into the adjustment tank is measured, and the pollution load or items correlated with the pollution load at the wastewater inlet to the wastewater treatment facility (wastewater treatment inlet) is estimated using the measured pollution load or items correlated with the pollution load and the first flow rate.

4. A method for estimating wastewater load according to claim 3, comprising measuring a second flow rate of wastewater flowing into the wastewater treatment facility, and estimating the wastewater load at the wastewater treatment inlet using the estimated pollution load at the wastewater inlet or an item correlated with the pollution load and the second flow rate.

5. A wastewater treatment method comprising switching the destination of wastewater flowing into the adjustment tank from the adjustment tank to a high-load adjustment tank when the wastewater load estimated by the method of claim 4 is greater than or equal to a predetermined value.

6. The wastewater treatment method according to claim 5, wherein, after switching the inflow destination of the wastewater from the adjustment tank to the high load adjustment tank, if the estimated wastewater load falls below a predetermined value, the wastewater in the high load adjustment tank is sent to the wastewater treatment facility.

7. The wastewater treatment method according to claim 5, wherein, after switching the inflow destination of the wastewater from the adjustment tank to the high load adjustment tank, if the estimated wastewater load falls below a predetermined value, the wastewater in the high load adjustment tank is sent to the adjustment tank.

8. The wastewater treatment method according to claim 5, wherein the adjustment tank into which the wastewater flows is arranged in parallel in multiple stages, and water is supplied from the adjustment tank to the wastewater treatment facility at a flow rate such that the estimated wastewater load does not exceed a predetermined value.

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