Wastewater treatment control device and wastewater treatment control method

Abstract

The present invention uses a wastewater treatment control device comprising: an environment / ecosystem monitoring unit 400 that determines the state of an environment / an ecosystem from environment index data 200 and ecosystem index data 300; an effluent water quality target value setting unit 500 that sets a target value of effluent water quality on the basis of the determination result from the environmental ecosystem monitoring unit 400 and general water quality data 100 including the water quality at a discharge destination of wastewater; and an operation control unit 600 that controls the operation of a wastewater treatment facility such that the effluent water quality reaches the target value. As a result, operation of the wastewater treatment facility can be controlled by using, as an index, the water quality at the discharge destination of the wastewater, that is, the water quality outside the facility.

Description

Wastewater treatment control device and wastewater treatment control method

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

[0002] To achieve carbon neutrality by 2050, ２ DAC (Direct Air Capture) is attracting attention as a negative emission technology. ２ There is an industrial method using amine as an absorbent, but this method ２ Separation of these requires energy costs.

[0003] There are methods that utilize ecosystems to address this issue. For example, CO2 is removed from the atmosphere by the growth of land plants. ２ Absorption (recovered carbon is called "green carbon"), CO2 from the atmosphere through coastal plant growth ２ There is absorption (the captured carbon is called "blue carbon").

[0004] Coastal plants and CO ２ One way to promote absorption is to supply nutrients such as phosphorus, nitrogen, and potassium. If there are too many nutrients, the ocean will become eutrophic, causing a massive outbreak of phytoplankton and other organisms, which can lead to water pollution such as red tides. Until now, sewage treatment plants, food factories, and other facilities have discharged purified wastewater into rivers and the ocean in accordance with discharge standards. 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, aiming to create a "clean and bountiful sea."

[0005] Patent Document 1 discloses a wastewater treatment system that includes an aerated contact oxidation tank, 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 rate of the contact oxidation tank. Patent Document 1 also describes 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.

[0006] Japanese Patent Application Laid-Open No. 2004-082041

[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 an index, and does not use the water quality of the environment or ecosystem into which the wastewater is discharged as an index.

[0009] An object of the present disclosure is to control the operation of a wastewater treatment facility using the destination of the wastewater discharge, that is, the water quality outside the facility, as an index.

[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 from 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 / 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.

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

[0013] Fig. 2 is a block diagram showing a wastewater treatment control device of Example 1. Fig. 3 is a flow diagram showing an example of a process in the environment / ecosystem monitoring unit of Fig. 1. Fig. 4 is a graph showing an example of a change in chlorophyll a over time in Example 1. Fig. 5 is a flow diagram showing an example of a process in the effluent quality target value setting unit of Fig. 1. Fig. 6 is a graph showing an example of a target value of effluent quality in Example 1. Fig. 7 is a flow diagram showing an example of a process in the effluent quality target value setting unit according to Example 2.

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

[0015] In this embodiment, an example of the configuration 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 system shown in this figure is composed of general water quality data 100, which includes general water quality parameters such as water temperature and pH at the wastewater discharge destination; environmental index data 200, which includes chlorophyll-a concentration and other indicators of environmental changes such as red tides; ecosystem index data 300, which includes data on biological metabolites and environmental DNA, which are indicators of biodiversity such as the number and quantity of biological species; an environment / ecosystem monitor 400 that determines the state of the environment and ecosystem based on the environmental index data 200 and ecosystem index data 300; an effluent quality target value setting unit 500 that sets a target value for effluent quality based on the results of the environment / ecosystem monitor 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 quality (actual effluent quality) reaches the target value. Solid lines in the figure indicate the flow of data.

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

[0019] An example of an application of a wastewater treatment control device is a sewage treatment plant, where the effluent is treated sewage water discharged as a result of treatment of wastewater in the sewage treatment plant (which may be 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 above example will be used to provide a detailed description. 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 referred to as "facilities."

[0021] The general water quality data 100 includes items that are the general water quality of the discharge destination and target values ​​for operational control. Specifically, general water quality includes water temperature, pH, alkalinity, electrical conductivity, ORP (Oxidation-Reduction Potential), DIC (Dissolved Inorganic Carbon, dissolved inorganic carbon including carbon dioxide, carbonic acid, carbonate ions, bicarbonate ions, etc.). Although not water quality, the data also includes solar radiation (amount of light) and wind volume (wind speed and direction). Items that are target values ​​for operational control include TP (Total Phosphorus), TN (Total Nitrogen), and, within total nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen. 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 levels are too high, eutrophication can cause red tides and blue-green algae, but if they are too low, it can lead to seaweed denudation, so it is important to keep them within an 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, the items include chlorophyll a, which is an indicator of red tides, etc., as well as 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 Tokyo, the total amount of chlorophyll a and phaeopigments measured by the Lorenzen method is 50 mg / m ３ If it is above this level, 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 as 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 with 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 suspended matter that is not dissolved in water. When there is a lot of insoluble suspended matter, the water becomes cloudy and visibility decreases. When water becomes cloudy, sunlight is blocked, inhibiting the photosynthesis of underwater plants. Also, oxygen is consumed in the decomposition of suspended matter, so the higher the SS, the more adversely it affects the aquatic organisms.

[0030] DO is the amount of oxygen dissolved in water. Microorganisms need oxygen to break down organic matter in the water. A drop in bottom DO can lead to the death of benthic organisms, blue tides, and the generation of hydrogen sulfide from the bottom sediment. Therefore, the lower the DO, the worse the water quality.

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

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

[0033] Biological metabolites are compounds synthesized by organisms within their bodies to sustain life, i.e., compounds produced by metabolism. Examples include dimethyl sulfide, a low-molecular-weight volatile organic compound (VOC) produced primarily by seaweed and phytoplankton, and persistent organic matter produced by seaweed and marine algae. Measuring the amount of these metabolites in the water at the release site allows us to understand the condition of phytoplankton and coastal plants.

[0034] Environmental DNA is a general term for DNA derived from living organisms present in environments such as the water of oceans, rivers, lakes, and other bodies of water, as well as soil and the atmosphere. For example, small amounts of environmental DNA from fish are present in the water at a given location through excrement, mucus, shed scales and skin, and dead fish. Collecting water samples is easy, and analyzing the environmental DNA in collected water allows for estimation of the species, presence, and population of fish in the release location, without the need to collect or observe the fish themselves.

[0035] The underwater camera takes images of the water in the release area, and by combining this with image analysis, it is possible to determine the number and quantity of living species. In addition, macro images taken by satellites can be used to determine 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 example, dimethyl sulfide is measured as a biological metabolite.

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

[0038] The environment / ecosystem monitoring unit 400 determines 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, the target value of the environmental index is obtained. Here, the target value of the environmental index refers to the upper and lower limit thresholds that are determined in advance at the discharge destination so as not to adversely affect the environment. In this example, chlorophyll a is used as the environmental index, and its upper limit as the 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 for chlorophyll a is set, but multiple target values ​​may be set depending on conditions such as the season. In this case, a process is added in which conditions such as date and time are also input to determine which target value to use.

[0041] In step S02, a measured value of an environmental index is acquired, which is the environmental index data 200. In this embodiment, this 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 determined. The target value and the measured value of the environmental index are compared according to the following formula (1), and it is determined whether the measured value of the environmental index is within a predetermined range.

[0043] (Measured value of environmental index)<(Target value of environmental index) 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 acquired, and when the measured value exceeds the index value, an alarm for exceeding the environmental index is issued. Here, the comparison of the index value and the measured value in the environment / ecosystem monitoring unit 400 is preferably made in units of one hour, taking into consideration fluctuations over one day (24 hours) in the wastewater treatment of the discharge destination / facility, but it may also be made in units of one day (for example, at a specified time), and there are no particular limitations as long as it can be determined 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 Figure 2, in step S04, a target value of the ecosystem index is acquired. Here, the target value of the ecosystem index refers to a value determined in advance at the discharge destination that indicates the maintenance or expansion of a healthy ecosystem. In this example, the target value is a VOC (e.g., dimethyl sulfide) that is a biological metabolite. The target value of dimethyl sulfide is determined in advance for each discharge destination and stored in a memory area of ​​a wastewater treatment control device (not shown).

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

[0048] In step S05, the measured value of the ecosystem index is acquired, which is the ecosystem index data 300. In this embodiment, this is VOC (e.g., 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 determined. The target values ​​of the ecosystem indicators are compared with the measured values ​​to determine 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 determination 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 Figure 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 sound 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.

[0052] The effluent water quality target value setting unit 500 calculates the 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.

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

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

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

[0058] In step S12, the target value and the measured value of TP are compared as shown in 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) Here, if the TP measurement value is smaller than the TP target value, it is determined that the nutrient discharge amount can 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 operational control, is obtained, as in step S10. The target value of TN is stored in a memory 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 also stored in a memory 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 whether the amount of nutrients discharged to the discharge destination is increased or decreased.

[0063] (TN measurement value)<(TN target value) ... Equation (3) Here, if the TN measurement value is smaller than the TN target value, it is determined that the nutrient discharge amount can 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 target values ​​for the effluent quality of TP and TN, i.e., target values ​​for wastewater treatment within the facility (hereinafter referred to as "facility target values"), and transmits the information. Here, the facility target values ​​are upper and lower limit values ​​of TP and TN for the effluent that can be controlled within the facility's operating range, 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 to the facility target values ​​in order to reduce the nutrient concentration in the effluent. Furthermore, 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 to the facility target values ​​in order to reduce the nutrient concentration in the effluent. If the measured values ​​of the environmental index, ecosystem index, and TP or TN are all within the predetermined range, the upper limit values ​​of TP and TN are set to the facility target values ​​in order to increase the nutrient concentration in the effluent.

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

[0066] In this figure, the horizontal bars for TP and TN on the vertical axis indicate the ranges 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. The points plotted on the horizontal bars indicate measured values.

[0067] If either the environmental indicator or the ecosystem indicator exceeds a predetermined range, or if the measured values ​​of TP or TN exceed a predetermined range, feedback is performed so that the TP and TN concentrations in the effluent fall within the predetermined range. Conversely, if the environmental indicator, the ecosystem indicator, and the measured values ​​of TP and TN are all within the predetermined range, feedback is performed so that the TP and TN concentrations in the effluent fall within the upper limit. Here, as with the environment / ecosystem monitoring unit 400, the comparison of the target value and the measured value in the effluent quality target value setting unit 500 is preferably performed on an hourly basis, taking into account fluctuations over a 24-hour period in the wastewater treatment of the effluent destination / facility. However, daily intervals are also acceptable, and are not particularly limited as long as a judgment can be made before the environment of the effluent destination deteriorates.

[0068] The effluent water quality target value setting unit 500 makes it possible to determine whether the nutrient salt concentration in the effluent water 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 sedimentation treatment, but there is also biological phosphorus removal technology. Taking the case of removing phosphorus using a coagulant (polyaluminum chloride, PAC) as an example, the correction value for the amount of coagulant to be added can be calculated using the following formula (4):

[0071] ΔPAC(t)=C1・(TP(t)−TP Ｔ (t)) + C2·ΔPAC(t−τ) ... Equation (4) Here, the above equation (4) is a feedback control using 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, 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 corrected amount of flocculant to be added using the above formula (4) and presenting it to the operator, the operator can correct the current amount of flocculant to be added. This will promote carbon absorption and storage in the marine area 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 ammonia nitrogen contained in wastewater is oxidized to nitrate by nitrifying bacteria 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 is calculated using the following formula (5):

[0074] ΔAIR(t)=C3・(TN(t)−TN Ｔ (t)) + C4·ΔAIR(t−τ) ... Equation (5) Here, like Equation (4), Equation (5) uses feedback control, PI control consisting of a proportional term and an integral term. C3 and C4 are coefficients, TN(t) is the TN concentration at time t, 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 corrected 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, which 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 to be 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 on the control method as long as it can correct the amount of flocculant to be 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. The communication means is not particularly limited and may be a wireless LAN, a wired LAN, or any other means. Furthermore, the hardware of the environment / ecosystem monitoring unit 400, the effluent water quality target value setting unit 500, and the operation control unit 600 includes a CPU, memory, hard disk, etc. (not shown). Furthermore, the software for 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 with a network interface. The installation location of this computer or the like is not particularly limited.

[0078] The general water quality data 100, environmental index data 200, and ecosystem index data 300 may be obtained by installing separate instruments at the locations where measurements are desired, or by installing instruments at a facility 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] This embodiment allows the discharged water to have an appropriate nutrient concentration set in response to changes in conditions inside and outside the facility, thereby promoting carbon absorption and storage in the marine area and maintaining the environment and biodiversity of the discharged water.

[0080] The target values ​​for the optimum TP and TN concentrations at the discharge destination vary depending on the type of marine plant. Furthermore, because marine plants do not grow throughout the year, the optimum TP and TN concentrations vary depending on the season. For this reason, the optimum TP and TN concentrations according to the season can be linked to data on the period for which they are applied, recorded in a database (not shown), and then retrieved and used by the discharge water quality target value setting unit 500.

[0081] In this embodiment, TP and TN are the targets of control, 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 released 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 these indicators may be input into the effluent quality target value setting unit 500 and used to determine the facility target value.

[0082] In this example, chlorophyll a was used as an example of an indicator of red tide, but there is no particular limitation as long as it can detect the occurrence of red tide. In addition to chlorophyll a, seawater colors such as brownish-brown, yellowish-brown, and green can also be used to determine whether a red tide has occurred. It may also be determined that a red tide has occurred when the transparency has dropped 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 item of chlorophyll a, BOD, COD, SS, DO, transparency, seawater color, and plankton count at the discharge destination.

[0084] The growth of marine plants is also affected by factors such as sunlight duration, light intensity, water temperature, and pH. High light intensity promotes photosynthesis, which allows marine plants to grow. Each type of marine plant has its own optimum water temperature and pH range for growth. Because marine plant growth differs depending on the light intensity, water temperature, and pH, it is necessary to change the optimum TP and TN concentrations.

[0085] In the second embodiment, a wastewater treatment control device will be described in detail, taking 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 the 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, similar to step S08, the suitability of the environment and ecosystem determined 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, using the following formula (6).

[0090] (Optimum TP concentration)=α·L (6) where α is a coefficient.

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

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

[0093] In this example, the process shown in FIG. 6 makes it possible to present recommended values ​​for TP concentration and TN concentration 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 of the discharge destination is acquired.

[0095] In step S21, similar 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 is increased or decreased.

[0096] In step S22, similar to step S19, the amount of light L at the discharge destination measured using 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 acquired.

[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 is to increase or decrease.

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

[0100] In this example, the process shown in FIG. 6 makes it possible to present recommended values ​​for TP concentration and TN concentration according to the plant growth conditions, and enables more appropriate nutrient salt supply compared to Example 1.

[0101] Additional advantages of the present disclosure are as follows:

[0102] According to this disclosure, it is possible to supply appropriate nutrients to marine areas, which will contribute to the CO2 reduction by coastal plants while maintaining the environment and biodiversity. ２ This will promote absorption and enable monetization as carbon credits. In addition, by optimizing nutrient supply, operation will be carried out in a way that increases the nutrient concentration in the nutrient-containing water at the source, which will result in a reduction in the energy costs of treating the source.

[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. A wastewater treatment control device comprising: 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 from the determination results of the environment / ecosystem monitoring unit and general water quality data including the water quality of the destination of the wastewater; and an operation control unit that controls the 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. A wastewater treatment control device as described in 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. A wastewater treatment control device as described in 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. A 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 obtained by an underwater camera or a satellite.

6. The wastewater treatment control device according to claim 1, wherein the ecosystem index data is dimethyl sulfide, and 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. A wastewater treatment control device as described in claim 7, wherein the effluent water quality target value setting unit calculates a correction value for the amount of coagulant to be added for the removal of total phosphorus, and calculates a correction value for the amount of air to be blown into the nitrification tank for the removal of total nitrogen.

9. A wastewater treatment control device as described in claim 7, wherein the effluent water quality target value setting unit changes the optimal TP concentration and optimal 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. A wastewater treatment control method comprising: a step in which an environment / ecosystem monitoring unit determines the state of the environment / 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 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 a wastewater treatment facility so that the effluent water quality reaches the target value.

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