Wastewater treatment control device and wastewater treatment control method

Abstract

To provide a wastewater treatment control device that controls operation of a wastewater treatment facility based on an indicator such as water quality outside the facility, i.e., a discharge destination of wastewater.SOLUTION: A wastewater treatment control device comprises: an environment / ecosystem monitoring unit 400 that determines a state of an environment / ecosystem based on environment index data 200 and ecosystem index data 300; a discharge water quality target value setting unit 500 that sets a target value of discharge water quality based on a determination result of the environment / ecosystem monitoring unit 400 and general water quality data 100 including water quality of a discharge destination of wastewater; and an operation control unit 600 that controls operation of the wastewater treatment facility so that the discharge water quality reaches the target value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a wastewater treatment control device and a wastewater treatment control method. [Background technology]

[0002] Direct Air Capture (DAC), which directly captures CO2, is attracting attention as a negative emission technology to achieve carbon neutrality by 2050. One example of DAC is an industrial method that uses amines as a CO2 absorbent, but this method requires energy costs to separate the absorbed CO2.

[0003] In response to this, there are methods that utilize ecosystems, such as absorbing CO2 from the atmosphere through the growth of land plants (the captured carbon is called "green carbon") and absorbing CO2 from the atmosphere through the growth of coastal plants (the captured carbon is called "blue carbon").

[0004] One method of promoting CO2 absorption by coastal plants is to supply nutrients such as phosphorus, nitrogen, and potassium. If there are too many nutrients, the sea will become eutrophic, causing a mass outbreak of phytoplankton and other organisms, which will lead to red tides and other water pollution. Until now, wastewater purified in accordance with discharge standards at sewage treatment plants, food factories, and other facilities has been discharged into rivers and the sea. However, because purified wastewater is poor in nutrients, it can have adverse effects on coastal ecosystems, such as sea denudation. For this reason, the Act on Special Measures for Conservation of the Environment of the Seto Inland Sea was revised in 2015 to aim for a "clean and abundant sea."

[0005] Patent Document 1 discloses a wastewater treatment system that has a contact oxidation tank for aeration, an intermediate tank, and a discharge tank, monitors the water quality of the intermediate tank and the discharge tank, determines the amount of microorganisms to be added, and controls the aeration amount of the contact oxidation tank. Patent Document 1 also discloses that the following are monitored: BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), SS (Suspended Solids), and normal hexane extract (mineral oils, animal and vegetable oils) content. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-082041 A Summary of the Invention [Problem to be solved by the invention]

[0007] If there is too much nutrient salt discharged into the ocean, it can cause problems such as eutrophication, and if there is too little, it can cause problems such as coastal barrenness. Therefore, in order to appropriately supply nutrients from wastewater to the ocean, it is desirable to consider carbon absorption and storage in the ocean, as well as the environment and biodiversity.

[0008] The wastewater treatment system described in Patent Document 1 uses the water quality of the intermediate tank and the discharge tank as indicators, and does not use the water quality of the environment or ecosystem where the wastewater is discharged as indicators.

[0009] An object of the present disclosure is to control the operation of a wastewater treatment facility using the water quality of the destination of the wastewater discharge, i.e., outside the facility, as an indicator. [Means for solving the problem]

[0010] The wastewater treatment control device disclosed herein comprises an environment / ecosystem monitoring unit that determines the state of the environment and ecosystem from environmental indicator data and ecosystem indicator data, an effluent water quality target value setting unit that sets a target value for effluent water quality based on the determination results of the environment / ecosystem monitoring unit and general water quality data including the water quality of the wastewater discharge destination, and an operation control unit that controls the operation of the wastewater treatment facility so that the effluent water quality reaches the target value.

[0011] The wastewater treatment control method disclosed herein includes a step in which an environment / ecosystem monitoring unit determines the state of the environment and ecosystem from environmental indicator data and ecosystem indicator data, a step in which an effluent water quality target value setting unit sets a target value for the effluent water quality from the determination result of the environment / ecosystem monitoring unit and general water quality data including the water quality of the destination of the wastewater, and a step in which an operation control unit controls the operation of the wastewater treatment facility so that the effluent water quality reaches the target value. Effect of the Invention

[0012] According to the present disclosure, the operation of a wastewater treatment facility can be controlled using the water quality of the destination of the wastewater discharge, i.e., outside the facility, as an index. [Brief description of the drawings]

[0013] [Figure 1] 1 is a configuration diagram showing a wastewater treatment control device of a first embodiment. [Diagram 2] FIG. 2 is a flow diagram showing an example of the process in the environment / ecosystem monitoring section of FIG. 1. [Diagram 3] 2 is a graph showing an example of the change in chlorophyll a over time in Example 1. [Figure 4] 2 is a flow chart showing an example of a process in a section for setting a target value of effluent water quality in FIG. 1. [Diagram 5] 2 is a graph showing an example of target values ​​of effluent water quality in Example 1. [Figure 6] FIG. 11 is a flow chart showing an example of a process in a effluent water quality target value setting unit according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment will be described with reference to the drawings. EXAMPLES

[0015] In this embodiment, a configuration example of a wastewater treatment control device will be described.

[0016] FIG. 1 is a configuration diagram showing a wastewater treatment control device according to a first embodiment.

[0017] The wastewater treatment control device shown in this figure is composed of general water quality data 100 including general water quality items such as water temperature and pH of the wastewater discharge destination, environmental indicator data 200 including chlorophyll a concentration that is an indicator of environmental changes such as red tides, ecosystem indicator data 300 including data on biological metabolites and environmental DNA that are indicators of biodiversity such as the number and amount of biological species, an environment / ecosystem monitoring unit 400 that judges the state of the environment / ecosystem from the environmental indicator data 200 and the ecosystem indicator data 300, an effluent water quality target value setting unit 500 that sets the target value of the effluent water quality from the judgment result of the environment / ecosystem monitoring unit 400 and the general water quality data 100, and an operation control unit 600 that controls the operation of the wastewater treatment facility so that the effluent water quality (actual effluent water quality) becomes the target value. The solid lines in the figure indicate the flow of data.

[0018] Here, the discharge destination refers to a specific sea area where coastal plants (for example, seagrass beds, algae beds) live, or a specific sea area that is expected to be affected by the supply of nutrients, including the range in which coastal plants live. Nutrients include a variety of inorganic salts, but in this embodiment, total phosphorus and total nitrogen are the focus.

[0019] An example of an application of the wastewater treatment control device is a sewage treatment plant. In this case, the discharged water is treated sewage water discharged as a result of treatment in the sewage treatment plant (which is composed of, for example, a grit basin, a primary sedimentation basin, a reaction tank, a final sedimentation basin, a disinfection facility, etc.).

[0020] In this embodiment, the details will be described using the above example. However, the wastewater treatment control device is applied to various wastewater treatment facilities. In this specification, wastewater treatment facilities include sewage treatment facilities, industrial wastewater treatment facilities, etc. For example, food factories that discharge water containing nutrients are also included in wastewater treatment facilities. Note that wastewater treatment facilities are also simply called "facilities."

[0021] The general water quality data 100 includes items that are the general water quality of the discharge destination and target values ​​for operation control. Specifically, the general water quality includes water temperature, pH, alkalinity, electrical conductivity, ORP (Oxidation-Reduction Potential), DIC (Dissolved Inorganic Carbon, including carbon dioxide, carbonic acid, carbonate ions, bicarbonate ions, etc.). In addition, although not water quality, it also includes solar radiation (amount of light) and wind volume (wind speed, wind direction). In addition, items that are the target values ​​for operation control include TP (Total Phosphorus), TN (Total Nitrogen), and among total nitrogen, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, etc. TP and TN are also included in the general water quality data 100.

[0022] In summary, the general water quality data includes at least one of the following items: water temperature, pH, alkalinity, electrical conductivity, ORP, DIC, sunshine hours, light intensity, wind speed, wind direction, total phosphorus, and total nitrogen at the discharge destination.

[0023] TP and TN are phosphorus and nitrogen present in water. If these are too high, eutrophication can lead to red tides and blue-green algae blooms, but if they are too low, they can lead to seaweed barrenness, so it is important to keep them within the appropriate range.

[0024] For at least TP and TN, data on the discharge destination is acquired and input to the discharge water quality target value setting unit 500 .

[0025] The environmental indicator data 200 includes items that are indicators of environmental changes in the discharge destination. Specifically, in addition to chlorophyll a, which is an indicator of red tides, etc., these include BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), SS (Suspended Solids), DO (Dissolved Oxygen), etc.

[0026] Chlorophyll a is an indicator of the amount of phytoplankton that causes red tides. In the case of Tokyo, the total amount of chlorophyll a and phaeopigments measured by the Lorenzen method is 50 mg / m 3 If it is higher than this, it is judged to be a red tide.

[0027] BOD is an index of organic pollution, and indicates the amount of organic matter contained in water by the amount of oxygen required by microorganisms to oxidize and decompose it. The higher the BOD, the more oxygen is required for microorganisms to decompose organic matter, indicating poor water quality.

[0028] COD is the amount of oxygen consumed when oxidizing substances in water under certain conditions using a strong oxidizing agent (such as potassium permanganate). The substances that are oxidized include organic matter as well as inorganic substances such as nitrites and sulfides, but since it is mainly organic matter that is oxidized, like BOD, the higher the value, the worse the water quality.

[0029] SS is the general term for the amount of material that is not dissolved in water and is suspended in it. If there is a lot of insoluble suspended matter, the water becomes cloudy and its transparency decreases. When water becomes cloudy, sunlight is blocked, inhibiting the photosynthesis of plants in the water. In addition, oxygen is consumed to break down suspended matter, so the higher the SS, the more adverse the impact on living organisms in the water.

[0030] DO is the amount of oxygen dissolved in water. Oxygen is necessary for microorganisms to break down organic matter contained in the water. A decrease in bottom layer DO can cause the death of benthic organisms and blue tides, as well as the generation of hydrogen sulfide from the bottom sediment. For this reason, the lower the DO, the worse the water quality.

[0031] At the discharge site, at least one of the above items is obtained and input to the environment / ecosystem monitoring unit 400. In this embodiment, chlorophyll a is to be obtained.

[0032] The ecosystem indicator data 300 includes items that are indicators of biodiversity, such as the number and amount of biological species. Specifically, the items include biological metabolites, environmental DNA, and estimated values ​​of the number or amount of biological species or the area of ​​seaweed beds measured from image data of underwater cameras or artificial satellites.

[0033] Biological metabolites are compounds that organisms synthesize in their bodies to sustain life, that is, compounds produced by metabolism. For example, there is dimethyl sulfide, a low-molecular-weight volatile organic compound (VOC) produced mainly by seaweed and phytoplankton, and persistent organic matter produced by seaweed and marine algae. By measuring the amount of these metabolites in the water where they are released, the condition of phytoplankton and coastal plants can be understood.

[0034] Environmental DNA is a general term for DNA derived from living organisms that exists in the environment, such as the water of the sea, rivers, lakes, etc., soil, and air. For example, environmental DNA of fish exists in small amounts in the water at a given location through excrement, mucus, peeled off scales and skin, and dead bodies. It is easy to collect water samples, and by analyzing the environmental DNA in the collected water, it is possible to estimate the type, presence, and population of fish at the release site without collecting or observing the fish themselves.

[0035] The underwater camera takes pictures of the water in the area where the fish are released, and by combining this with image analysis, it is possible to grasp the number and quantity of each species. In addition, by using macro images taken by satellites, it is possible to grasp the area of ​​the seaweed beds.

[0036] At least one of these items is measured at the discharge site and input to the environment / ecosystem monitoring unit 400. In this embodiment, dimethyl sulfide is measured as a biological metabolite.

[0037] The general water quality data 100, the environmental index data 200 and the ecosystem index data 300 may be measured by installing a sensor at the discharge point, or published data may be obtained via a network or the like and used.

[0038] The environment / ecosystem monitoring unit 400 judges the state of the environment / ecosystem from the environmental indicator data 200 and the ecosystem indicator data 300 .

[0039] FIG. 2 is a flow diagram showing an example of the process in the environment / ecosystem monitoring unit 400 of FIG.

[0040] As shown in Fig. 2, first, in step S01, a target value of an environmental index is obtained. Here, the target value of an environmental index refers to upper and lower threshold values ​​that are determined in advance by the discharge destination and do not adversely affect the environment. In this embodiment, chlorophyll a is used as the environmental index, and its upper limit as a target value is set to 50 mg / m 3 This value is stored in a memory area of ​​a wastewater treatment control device (not shown). In this embodiment, one target value of chlorophyll-a is set, but multiple target values ​​may be set according to conditions such as the season. In that case, a process is added to determine which target value to use by inputting conditions such as date and time.

[0041] In step S02, a measured value of an environmental indicator is obtained, which is the environmental indicator data 200. In this embodiment, it is chlorophyll a. This value is stored in a memory area of ​​a wastewater treatment control device (not shown).

[0042] In step S03, the suitability of the environment of the discharge destination is judged. The target value and the measured value of the environmental index are compared according to the following formula (1), and it is judged whether the measured value of the environmental index is within a predetermined range.

[0043] (Measured value of environmental indicator) < (Target value of environmental indicator) ... Equation (1) FIG. 3 is a graph showing an example of the change in chlorophyll a over time in this example.

[0044] The index value and the measured value of the environmental index are periodically obtained, and when the measured value exceeds the index value, an alarm is issued to warn of an excess of the environmental index. Here, the comparison of the index value and the measured value in the environment / ecosystem monitoring unit 400 is preferably performed on an hourly basis, taking into consideration fluctuations in the wastewater treatment of the discharge destination / facility over a one-day (24-hour) period, but it may also be performed on a daily basis (for example, at a specified time), and is not particularly limited as long as it can be judged before the environment of the discharge destination deteriorates.

[0045] In this figure, the measured value of chlorophyll a in 24 hours is the upper limit of 50 mg / m 3 This indicates that the

[0046] Returning to FIG. 2, in step S04, a target value of an ecosystem index is acquired. Here, the target value of an ecosystem index refers to a value that is determined in advance for the discharge destination and indicates healthy maintenance or expansion of the ecosystem. In this embodiment, it is VOC (e.g., dimethyl sulfide) which is a biological metabolite. The target value of dimethyl sulfide is determined in advance for each discharge destination and is stored in a memory area of ​​a wastewater treatment control device (not shown).

[0047] Like environmental indices, ecosystem indices may have multiple target values ​​depending on conditions such as the season, in which case an additional process is added in which conditions such as date and time are also input to determine which target value to use.

[0048] In step S05, a measurement value of an ecosystem index is obtained, which is ecosystem index data 300. In this embodiment, it is VOC (for example, dimethyl sulfide). This value is also stored in a memory area of ​​the wastewater treatment control device (not shown).

[0049] In step S06, the suitability of the ecosystem of the release destination is judged. The target values ​​of the ecosystem indexes are compared with the measured values ​​to judge whether they are within the range of conditions for maintaining or expanding the healthy ecosystem.

[0050] In step S07, the information on the result of the suitability judgment is sent to the effluent water quality target value setting unit 500. Also, for example, a graph of the change over time as shown in Fig. 3 is displayed on a monitor or the like, and if the target value is exceeded, an alarm is displayed on the monitor. In this case, an alarm may be sounded to notify the operator directly.

[0051] The environment / ecosystem monitoring unit 400 makes it possible to determine whether the environment / ecosystem of the release destination is in an appropriate state or not.

[0052] The effluent water quality target value setting unit 500 calculates a target value for the water quality of the effluent water from the facility (effluent water quality) based on the water quality items that are the general water quality data 100 and information on whether the environment and ecosystem of the destination of the effluent water, transmitted from the environment and ecosystem monitoring unit 400, is in an appropriate state or not.

[0053] FIG. 4 is a flow diagram showing an example of a process in the effluent water quality target value setting unit 500 of FIG.

[0054] 4, in step S08, a suitability judgment of the environment and ecosystem is obtained by the environment and ecosystem monitoring unit 400. The suitability judgment is stored in a memory area of ​​the wastewater treatment control device (not shown).

[0055] In step S09, the suitability of the environment and ecosystem is classified. If the environmental indicators and ecosystem indicators are within the predetermined range, the environment and ecosystem are deemed to be in an appropriate state, and the process proceeds to step S10. Conversely, if either the environmental indicator or the ecosystem indicator exceeds the predetermined range, the process proceeds to step S16.

[0056] In step S10, a target value of TP, which is an index for operation control, is obtained. The target value of TP is stored in a storage area of ​​a wastewater treatment control device (not shown).

[0057] In step S11, a measured value of TP at the discharge destination is acquired. The measured value of TP, like the target value of TP, is also stored in a memory area of ​​a wastewater treatment control device (not shown).

[0058] In step S12, the target value and the measured value of TP are compared according to the following formula (2) to determine whether the amount of nutrients discharged to the discharge destination is increased or decreased.

[0059] (TP measurement value) < (TP target value) ... Equation (2) If the TP measurement value is smaller than the TP target value, it is determined that the nutrient discharge amount may be increased, and the process proceeds to step S13. Conversely, if the TP measurement value is equal to or greater than the TP target value, it is determined that the nutrient discharge amount needs to be decreased, and the process proceeds to step S16.

[0060] In step S13, a target value of TN, which is an index for operation control, is obtained, similarly to step S10. The target value of TN is stored in a storage area of ​​a wastewater treatment control device (not shown).

[0061] In step S14, the measured value of TN at the discharge destination is acquired, similar to step S11. The measured value of TN, like the target value of TN, is stored in a storage area of ​​the wastewater treatment control device (not shown).

[0062] In step S15, similarly to step S12, the target value and the measured value of TN are compared according to the following formula (3) to determine an increase or decrease in the amount of nutrients discharged to the discharge destination.

[0063] (TN measurement value) < (TN target value) ... Equation (3) If the TN measurement value is smaller than the TN target value, it is determined that the nutrient discharge amount may be increased, and the process proceeds to step S16. Conversely, if the TN measurement value is equal to or greater than the TN target value, it is determined that the nutrient discharge amount needs to be decreased, and the process proceeds to step S16.

[0064] In step S16, the operation control unit 600 sets the target values ​​of the effluent quality of TP and TN, that is, the target values ​​of the wastewater treatment in the facility (hereinafter referred to as "facility target values"), and transmits the information. Here, the facility target values ​​are the upper and lower limit values ​​of TP and TN of the effluent that can be controlled within the operation range of the facility, which are stored in advance in a memory area of ​​the wastewater treatment control device (not shown). Then, in step S09, if either the environmental index or the ecosystem index exceeds a predetermined range, the lower limit values ​​of TP and TN are set as the facility target values ​​in order to reduce the nutrient salt concentration contained in the effluent. Also, in steps S12 and S16, if the measured values ​​of TP or TN are equal to or greater than their respective target values, the lower limit values ​​of TP and TN are set as the facility target values ​​in order to reduce the nutrient salt concentration contained in the effluent. If the measured values ​​of the environmental index and ecosystem index, as well as TP or TN, are all within the predetermined range, the upper limit values ​​of TP and TN are set as the facility target values ​​in order to increase the nutrient salt concentration contained in the effluent.

[0065] 5 is a graph showing an example of target values ​​for effluent quality in Example 1. The vertical axis indicates TP and TN, and the horizontal axis indicates the respective concentrations in the effluent (effluent quality).

[0066] In this figure, the horizontal bars of TP and TN on the vertical axis indicate the range of TP and TN of the discharged water that can be controlled within the operating range of the facility, with the ends of each bar indicating the upper and lower limits. Also, the points plotted on the bars indicate the measured values.

[0067] When either the environmental index or the ecosystem index exceeds the predetermined range, or when the measured value of TP or TN exceeds the predetermined range, feedback is performed so that the concentrations of TP and TN in the effluent are within the predetermined range. Conversely, when the environmental index, the ecosystem index, and the measured values ​​of TP and TN are all within the predetermined range, feedback is performed so that the concentrations of TP and TN in the effluent are at the upper limit. Here, the comparison between the target value and the measured value in the effluent water quality target value setting unit 500 is preferably performed in hourly units, as in the environment / ecosystem monitoring unit 400, taking into consideration the fluctuations during one day (24 hours) of the wastewater treatment of the effluent destination / facility, but may be performed in daily units, and is not particularly limited as long as it can be determined before the environment of the effluent destination deteriorates.

[0068] The effluent quality target value setting unit 500 makes it possible to determine whether the nutrient salt concentration in the effluent should be controlled to a high or low level.

[0069] The operation control unit 600 calculates recommended setting values ​​for facility operation control based on the facility target values ​​of TP and TN set by the effluent water quality target value setting unit 500.

[0070] For TP, the mainstream phosphorus removal technology is coagulation and sedimentation, but there are also biological phosphorus removal technologies. As an example of removing phosphorus using a coagulant (polyaluminum chloride, PAC), the correction value for the amount of coagulant to be added is calculated using the following formula (4).

[0071] ΔPAC(t)=C1·(TP(t)-TP T (t)) + C2 · ΔPAC(t-τ) ...Formula (4) Here, the above formula (4) is a feedback control, and uses PI control consisting of a proportional term and an integral term. C1 and C2 are coefficients, t is time, TP(t) is the TP concentration at time t, and TP T (t) is the facility target value of TP at time t, ΔPAC(t) is the correction value of the coagulant addition amount at time t, ΔPAC(t-τ) is the correction value of the coagulant addition amount one control period (τ) before time t, and τ is the control period.

[0072] By calculating the correction value for the amount of flocculant added using the above formula (4) and presenting it to the operator, the operator can correct the current amount of flocculant added. This will promote carbon absorption and storage in the ocean and maintain the environment and biodiversity of the discharge destination.

[0073] The mainstream nitrogen removal technology for TN is biological nitrification / denitrification. In biological nitrification / denitrification, nitrogen is removed through a nitrification process in which nitrifying bacteria oxidize the ammonia nitrogen contained in the wastewater to nitrate in a nitrification tank, and a denitrification process in which the nitrate is converted into nitrogen gas. During this process, aeration is performed by blowing air into the nitrification tank. By changing the amount of air blown in, it is possible to change the nitrogen removal rate in the wastewater. For example, the correction value for the amount of air can be calculated using the following formula (5).

[0074] ΔAIR(t)=C3·(TN(t)-TN T (t)) + C4 ΔAIR(t-τ) …Equation (5) Here, the above formula (5) uses PI control consisting of a proportional term and an integral term in the feedback control, similar to the above formula (4). C3 and C4 are coefficients, TN(t) is the TN concentration at time t, and TN T (t) is the facility target value of TN at time t, ΔAIR(t) is the correction value of the coagulant addition amount at time t, and ΔAIR(t-τ) is the correction value of the coagulant addition amount one control cycle (τ) before time t.

[0075] By calculating the correction value for the amount of air to be injected using the above formula (5) and presenting it to the operator, the operator can correct the current amount of air. This will promote carbon absorption and storage in the ocean and maintain the environment and biodiversity of the discharge destination.

[0076] In this embodiment, the correction amount is calculated and presented to the operator, who then inputs the amount of flocculant added and the amount of air into an input unit of the wastewater treatment control device (not shown), but the calculated correction amount may be automatically sent to the operation control unit of the wastewater treatment control device, so that operation control is performed automatically without the intervention of the operator. Also, although PI control is used as an example, PID control may also be used, and there is no particular limitation as long as the control method can correct the amount of flocculant added and the amount of air.

[0077] In this embodiment, information is transmitted from the environmental index data 200 and ecosystem index data 300 to the environment / ecosystem monitoring unit 400, from the general water quality data 100 and the environment / ecosystem monitoring unit 400 to the effluent water quality target value setting unit 500, and from the effluent water quality target value setting unit 500 to the operation control unit 600. At this time, the communication means is not particularly limited, and may be wireless LAN, wired LAN, or any other means. In addition, a CPU, memory, hard disk, etc. (not shown) are used as the hardware of the environment / ecosystem monitoring unit 400, the effluent water quality target value setting unit 500, and the operation control unit 600. In addition, the software of the environment / ecosystem monitoring unit 400, the effluent water quality target value setting unit 500, and the operation control unit 600 is stored in a computer or the like having a network interface. The installation location of this computer or the like is not particularly limited.

[0078] The general water quality data 100, the environmental indicator data 200 and the ecosystem indicator data 300 may be obtained by installing separate instruments at the locations where measurements are desired, or by installing instruments at facilities such as a water quality measurement center and periodically sampling nutrient-containing water or seawater from the ocean area and bringing it to the center for measurements.

[0079] In this embodiment, the nutrient concentration of the discharged water can be set appropriately in response to changes in conditions inside and outside the facility, which promotes carbon absorption and storage in the marine area and makes it possible to maintain the environment and biodiversity of the discharged area.

[0080] The optimum TP concentration and optimum TN concentration of the discharge destination, which are the target values, differ depending on the type of marine plant. Also, since marine plants do not grow throughout the year, the optimum TP concentration and optimum TN concentration differ depending on the season. For this reason, a method is available in which the optimum TP concentration and optimum TN concentration according to the season are linked to data on the period for which they are applied, recorded in a database (not shown), and acquired and used by the discharge water quality target value setting unit 500.

[0081] In this embodiment, TP and TN are controlled, but when discharging effluent with a higher nutrient concentration than before, there is a possibility that substances that cause environmental pollution, such as BOD and COD, will also be discharged in high concentrations. Although BOD and COD are environmental indicators, it is possible to increase the amount removed by improving the treatment capacity of the facility, so such indicators may be input to the effluent quality target value setting unit 500 and used to determine the facility target value.

[0082] In this embodiment, chlorophyll a is used as an example of an indicator of red tide, but there is no particular limitation as long as the occurrence of a red tide can be grasped. In addition to chlorophyll a, the color of seawater such as brownish brown, yellowish brown, green, etc. can be used to determine whether a red tide has occurred. Also, it may be determined that a red tide has occurred when the transparency has decreased to approximately 1.5 m or less. It may also be determined that a red tide has occurred when a predetermined amount or more of red tide plankton is present under a microscope.

[0083] In summary, the environmental indicator data 200 includes at least one of the following items: chlorophyll-a, BOD, COD, SS, DO, transparency, seawater color, and plankton count at the discharge destination. EXAMPLES

[0084] The growth of marine plants is also affected by the hours of sunlight, the amount of light, the water temperature, and the pH level. If there is a lot of light, photosynthesis is promoted, and marine plants grow. Also, each type of marine plant has an optimal water temperature and pH range for growth. For this reason, the growth of marine plants differs depending on the amount of light, water temperature, and pH, so it is necessary to change the optimal TP and TN concentrations.

[0085] In the second embodiment, a wastewater treatment control device will be described in detail using the amount of light and the water temperature as examples of items of the general water quality data 100.

[0086] 6 is a flow chart showing an example of a process in a effluent water quality target value setting unit according to Example 2. Here, the configuration of the wastewater treatment control device is the same as that in FIG.

[0087] As shown in FIG. 6, in step S17, similarly to step S08, a suitability judgment of the environment and ecosystem judged by the environment and ecosystem monitoring unit 400 (FIG. 1) is obtained.

[0088] In step S18, the suitability of the environment and ecosystem is classified in the same manner as in step S09.

[0089] In step S19, the amount of light L at the discharge destination, which is the general water quality data 100 (FIG. 1), is acquired and the optimum TP concentration is calculated. The optimum TP concentration is calculated, for example, by the following formula (6).

[0090] (Optimal TP concentration)=α·L…Equation (6) Here, α is a coefficient.

[0091] In this embodiment, as an example, a case where marine plants grow in proportion to the amount of light L, that is, a case where the optimum TP concentration increases in proportion to the amount of light L, is shown, but there is no particular limitation as long as an appropriate relationship between the amount of light L and the optimum TP concentration can be obtained. Also, for example, when other items such as water temperature are added, the calculation may be performed using the following formula (7).

[0092] (Optimal TP concentration)=α·L+β·T…Equation (7) Here, β is a coefficient and T is the water temperature.

[0093] In this embodiment, the process shown in FIG. 6 makes it possible to present recommended values ​​for TP and TN concentrations according to the plant growth conditions, enabling a more appropriate supply of nutrients compared to Example 1.

[0094] In FIG. 6, following step S19, in step S20, similar to step S11, the measurement value of the TP at the discharge destination is acquired.

[0095] In step S21, similarly to step S12, the target value and the measured value of TP are compared to determine whether the amount of nutrients discharged to the discharge destination has increased or decreased.

[0096] In step S22, similar to step S19, the amount of light L at the discharge destination measured in the general water quality data 100 is acquired and the optimum TN concentration is calculated. The optimum TN concentration can also be calculated using an equation such as the above equation (6).

[0097] In step S23, similar to step S20, a measurement value of the TN of the discharge destination is obtained.

[0098] In step S24, similar to step S21, the target value of TN is compared with the measured value to determine whether the amount of nutrients discharged to the discharge destination has increased or decreased.

[0099] In step S25, similar to step S16, target values ​​for the effluent water quality of the TP and TN, that is, target values ​​for wastewater treatment in the facility (facility target values), are set and the information is transmitted to the operation control unit 600.

[0100] In this embodiment, the process shown in FIG. 6 makes it possible to present recommended values ​​for TP and TN concentrations according to the plant growth conditions, enabling a more appropriate supply of nutrients compared to Example 1.

[0101] Additional advantages of the present disclosure include:

[0102] According to this disclosure, it is possible to supply appropriate nutrients to the ocean, which will promote CO2 absorption by coastal plants while maintaining the environment and biodiversity, and can be monetized as carbon credits. In addition, if the optimization of nutrient supply leads to an increase in the nutrient concentration of the nutrient-containing water at the source, it will result in a reduction in the energy and cost of treating the source. [Explanation of symbols]

[0103] 100: general water quality data, 200: environmental index data, 300: ecosystem index data, 400: environment / ecosystem monitoring unit, 500: effluent water quality target value setting unit, 600: operation control unit.

Claims

1. an environment and ecosystem monitoring unit that determines the state of the environment and ecosystem from the environmental indicator data and the ecosystem indicator data; an effluent water quality target value setting unit that sets a target value for effluent water quality based on the determination result of the environment / ecosystem monitoring unit and general water quality data including the water quality of the effluent discharge destination; An operation control unit that controls operation of a wastewater treatment facility so that the effluent water quality reaches the target value.

2. The wastewater treatment control device according to claim 1 , further comprising equipment for measuring at least one of the general water quality data, the environmental index data, and the ecosystem index data.

3. The wastewater treatment control device according to claim 1, wherein the general water quality data includes at least one of the following items: water temperature, pH, alkalinity, electrical conductivity, ORP, DIC, sunshine hours, light intensity, wind speed, wind direction, total phosphorus, and total nitrogen at the discharge destination.

4. The wastewater treatment control device according to claim 1 , wherein the environmental index data includes at least one of chlorophyll a, BOD, COD, SS, DO, transparency, seawater color, and plankton count of the discharge destination.

5. The wastewater treatment control device as described in claim 1, wherein the ecosystem indicator data includes at least one of the following items: biological metabolites, environmental DNA, and an estimate of the number or quantity of biological species or the area of ​​a seaweed bed measured from image data from an underwater camera or an artificial satellite.

6. The ecosystem indicator data is dimethyl sulfide; The wastewater treatment control device according to claim 1 , wherein the environmental index data is chlorophyll a.

7. The wastewater treatment control device according to claim 1 , wherein the target values ​​of the effluent water quality are total phosphorus and total nitrogen.

8. The effluent water quality target value setting unit is For the removal of total phosphorus, a correction value for the amount of flocculant added is calculated, 8. The wastewater treatment control device according to claim 7, further comprising a correction value for the amount of air blown into the nitrification tank for removing the total nitrogen.

9. The wastewater treatment control device according to claim 7 , wherein the effluent water quality target value setting unit changes the optimum TP concentration and the optimum TN concentration set as the target values ​​of the effluent water quality using the amount of light or the amount of light and water temperature at the discharge destination.

10. An environment / ecosystem monitoring unit determining the state of the environment / ecosystem from the environmental indicator data and the ecosystem indicator data; a step of a effluent water quality target value setting unit setting a target value of the effluent water quality based on the judgment result of the environment / ecosystem monitoring unit and general water quality data including the water quality of the effluent discharge destination; and a step of controlling the operation of the wastewater treatment facility by an operation control unit so that the effluent water quality reaches the target value.

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