Plant operation support system

Abstract

This system provides a plant operation support system that can supply appropriate amounts of nutrients to specific points within the managed water area. [Solution] The plant operation support system S according to the present invention comprises: a nutrient control target value setting unit 3 that sets a control target value for nutrients discharged from one or more water treatment plants 1 that discharge nutrients and allow them to flow into a management water area 8; a management item constraint condition setting unit 4 that sets constraint conditions for management items in the management water area 8; a management item measurement unit 5 that measures management items in the management water area 8; a management water area environmental classification setting unit 6 that sets points for correcting constraint conditions for management items in the management water area 8; and a nutrient control target value correction unit 7 that calculates a correction result for the control target value based on the measured value measured by the management item measurement unit 5 and the constraint conditions set by the management item constraint condition setting unit 4, wherein the nutrient control target value setting unit 3 corrects the control target value based on the correction result.

Description

Technical Field

[0001] The present invention relates to a plant operation support system.

Background Art

[0002] Excessive nutrients abnormally increase phytoplankton in the sea area of the discharge destination, causing environmental pollution such as red tides and destruction of the ecosystem. During the high-growth period, as water pollution in closed waters became apparent as environmental pollution, advanced treatment to remove not only organic substances but also nutrients such as nitrogen and phosphorus in drainage was widespread in water treatment plants including sewage treatment plants for the purpose of improving the water environment of public waters. As a result, the water quality has improved in closed waters such as Tokyo Bay, Osaka Bay, Ise Bay, Seto Inland Sea, and Lake Biwa, and the ecosystem has recovered.

[0003] However, the removal of nutrients such as nitrogen and phosphorus has become excessive, thinning the nutrient concentration in the sea area where the treated sewage from the sewage treatment plant flows. As a result, it has caused stunted growth of nori, seaweed, and seaweed growing and cultivated in the sea area due to insufficient nutrients, and a decrease in zooplankton and fish due to poor growth of phytoplankton, which is primary production. From this, in recent years, there has been an increasing demand to preserve the water quality in a good state, appropriately supply nutrients from water treatment plants, and ensure greater biodiversity and productivity.

[0004] Regarding the sea, not only the harvest of nori, seaweed, seaweed, fish, etc. but also the decarbonization perspective is emphasized. In a report of the United Nations Environment Programme (UNEP) in October 2009, the carbon incorporated into marine ecosystems such as seaweed beds and shallow fields was named "blue carbon" and presented as a new option for countermeasures against CO2 absorption sources.

[0005] Recent research has shown that the amount of carbon absorbed and sequestered by marine ecosystems (blue carbon) is comparable to the amount absorbed and sequestered on land (green carbon). Therefore, there are high expectations for the utilization of blue carbon as an initiative to enrich marine ecosystems while achieving carbon neutrality. Furthermore, in recent years, trials and applications for "J-Blue Credits" have begun to accelerate efforts toward climate change mitigation and adaptation in other coastal areas and oceans, and to recognize the role of marine ecosystems (blue carbon ecosystems) as CO2 sinks that sequester and store blue carbon. J-Blue Credits are quantifiable and tradable credits of blue carbon. Through the trading of these credits, it is expected that economic value can be enjoyed through sales profits, and social and environmental value can be contributed to the creation of rich marine ecosystems and the role of natural breakwaters through the creation and purchase of these credits.

[0006] The amount of blue carbon is expressed as the distribution area of ​​the target ecosystem × absorption coefficient (wet weight per unit area × blue carbon retention rate). Examples of target ecosystems include seagrass beds such as eelgrass beds, eelgrass, dwarf eelgrass, slender eelgrass, and Ryukyu slender eelgrass; seaweed beds such as Sargassum beds, Sargassum fuscoguttatum, Sargassum erythrosora, Sargassum fuscoguttatum, Sargassum sarmentosum, and Sargassum sarmentosum; kelp beds such as kelp beds, Laminaria japonica, Laminaria tetrandra, Laminaria japonica, and Sargassum fuscoguttatum; wakame seaweed beds, wakame seaweed, and Sargassum fuscoguttatum; tengusa beds, Laminaria japonica, and Sargassum fuscoguttatum; mangroves, tidal flats, phytoplankton, and zooplankton.

[0007] Structures such as artificial reefs, seawalls, aquaculture facilities, and offshore wind power plants serve as footholds for seaweed beds, contributing to the stable growth of seagrass and seaweed. For this reason, J Blue Credit applications are often made for seagrass and seaweed beds located at sites related to these structures.

[0008] Blue carbon ecosystems, which act as CO2 sinks, increase in rich oceans where nutrients are properly managed. Increasing the distribution area and wet weight per unit area, thereby enhancing the value of blue carbon credits, requires the management of nutrients, which are equivalent to fertilizers. Therefore, monitoring nutrients in marine areas and managing water treatment plants such as sewage treatment plants that discharge these nutrients are crucial.

[0009] Under these circumstances, for example, Patent Document 1 proposes an invention aimed at providing an operation support device for a wastewater treatment facility that incorporates a method / process for contributing to an increase in the amount of blue carbon. Specifically, Patent Document 1 describes an operation support device that assists in the operation of a wastewater treatment facility that discharges treated wastewater. This device has a managed water area information acquisition mechanism that acquires observation results of predetermined management items in a managed water area to which the treated wastewater discharged by the wastewater treatment facility flows. This device has a management item constraint condition setting mechanism that sets constraint conditions for the predetermined management items in the managed water area. This device has a nutrient control target setting mechanism that sets control targets for nutrients contained in the treated wastewater. This device has a nutrient control target modification mechanism that compares the observation results of the predetermined management items from the managed water area information acquisition mechanism with the constraint conditions and sets modified control targets. This device has a nutrient control mechanism that controls the concentration of nutrients contained in the treated wastewater based on the modified control targets. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2024-33452 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, the invention described in Patent Document 1 did not adequately consider supplying appropriate amounts of nutrients to specific locations in blue carbon ecosystems, such as seagrass beds and seaweed beds, within the managed water area, and there was room for improvement in this respect.

[0012] The present invention has been made in view of the above circumstances. The object of the present invention is to provide a plant operation support system that can supply an appropriate amount of nutrients to a specific point within a controlled water area. [Means for solving the problem]

[0013] The plant operation support system according to the present invention, which solves the above problems, comprises: a nutrient control target value setting unit that sets a control target value for nutrients discharged from one or more water treatment plants that discharge nutrients and allow them to flow into a controlled water area; a control item constraint condition setting unit that sets constraint conditions for control items in the controlled water area; a control item measurement unit that measures control items in the controlled water area; a controlled water area environment classification setting unit that sets points for correcting constraint conditions for control items in the controlled water area; and a nutrient control target value correction unit that calculates a correction result for the control target value based on the measured value measured by the control item measurement unit and the constraint conditions set by the control item constraint condition setting unit, wherein the nutrient control target value setting unit corrects the control target value based on the correction result. [Effects of the Invention]

[0014] According to the present invention, a plant operation support system can be provided that can supply an appropriate amount of nutrients to a specific point within a managed water area. Other issues, configurations, and effects not mentioned above will be revealed by the following description of embodiments. Further features related to the present invention will be revealed by the description herein and the accompanying drawings. [Brief explanation of the drawing]

[0015] [Figure 1] This is a diagram showing the configuration of the plant operation support system S according to the first embodiment of the invention. [Figure 2] It is an explanatory diagram for explaining the management water area 8.

Embodiments for Carrying out the Invention

[0016] Hereinafter, an organic compound decomposition apparatus according to an embodiment of the present invention will be described while appropriately referring to the drawings. In the following description and drawings, the same reference numerals may be given to common configurations, and duplicate descriptions may be omitted. Further, the present invention is not limited to the following embodiments. Furthermore, the description in this specification is merely a typical example and does not limit the scope of the claims or application examples in any sense.

[0017] [First Embodiment] FIG. 1 is a configuration diagram of a plant operation support system S according to the first embodiment of the present invention. This plant operation support system S supports the operation of the water treatment plant 1. As shown in FIG. 1, the plant operation support system S includes a nutrient control target value setting unit 3, a management item constraint condition setting unit 4, a management item measurement unit 5, a management water area environment classification setting unit 6, and a nutrient control target value correction unit 7. The plant operation support system S also includes a monitoring control unit 2.

[0018] The water treatment plant 1 discharges nutrients and allows them to reach the management water area 8. The monitoring control unit 2 monitors and controls the water treatment plant 1. The nutrient control target value setting unit 3 sets the control target value of the nutrients discharged from one or more water treatment plants 1 that discharge nutrients and allow them to reach the management water area 8. The management item constraint condition setting unit 4 sets the constraint conditions of the management items in the management water area 8. Here, the constraint conditions are lower limit values and upper limit values that are appropriately set as described later. The management item measurement unit 5 measures the management items in the management water area 8. The management water area environment classification setting unit 6 sets the points for correcting the constraint conditions of the management items in the management water area 8. The nutrient control target value correction unit 7 calculates a correction result (correction policy) of the control target value based on the measured value measured by the management item measurement unit 5 and the constraint condition set by the management item constraint condition setting unit 4. And in the present embodiment, the nutrient control target value setting unit 3 corrects the control target value based on the above-described correction result. Hereinafter, specific embodiments will be described.

[0019] The water treatment plant 1 has a monitoring control unit 2 that acquires sensor values and operates devices. The water treatment plant 1 treats public sewage, industrial wastewater, agricultural wastewater, domestic wastewater, etc. according to the nutrient control target value setting unit 3 that sets the control target value of nutrients, and discharges them into rivers, lakes, and seas. The discharged treated water merges with surrounding environmental water, treated water from other water treatment plants, etc., and reaches the management water area 8 such as lakes, bays, inner bays, inland seas, outer seas, seas, and water areas. The management water area 8 has a management item measurement unit 5. The nutrient control target value correction unit 7 calculates a correction result of the control target value of nutrients based on the measured value of the management item measured by the management item measurement unit 5 and the constraint condition of the management item constraint condition setting unit 4 that sets the constraint condition regarding the management item. The nutrient control target value setting unit 3 corrects the control target value of nutrients based on the above-described correction result. Note that the management water area location of the management water area 8 (that is, the location where the constraint condition of the management item in the management water area 8 is corrected) is classified and set by the management water area environment classification setting unit 6. The prior art (for example, the invention described in the above-mentioned Patent Document 1) does not have the management water area environment classification setting unit 6, and thus is different from the present invention in that it is not always possible to appropriately classify and set the location where the constraint condition of the management item in the management water area 8 is corrected. The management item constraint condition setting unit 4 corrects the constraint condition based on the setting information classified and set by the management water area environment classification setting unit 6.

[0020] In the first embodiment, the control item targeted by the nutrient control target value setting unit 3 is the total nitrogen discharge amount, the management water area 8 is an inner bay, and the management item in the management water area 8 is the total nitrogen concentration. Total nitrogen concentration is an indicator that correlates with phytoplankton concentration. Phytoplankton concentration fluctuates due to factors such as number density, cell density, and species (same species, different types). Excessively high total nitrogen and phytoplankton concentrations can cause environmental damage such as red tides. Conversely, excessively low total nitrogen and phytoplankton concentrations can impair the growth of marine ecosystems or lead to economic losses due to energy consumption from over-processing.

[0021] Figure 2 is an explanatory diagram illustrating the managed water area 8. In the example shown in Figure 2, effluent discharged from the water treatment plant 1 is discharged into the managed water area 8 (sea area) via a river. The managed water area within the sea area is divided into a 4x6 zone, within which there are points PA and PB. The settings for this zone and points PA and PB are made in the managed water area environmental zone setting unit 6 as described above. Points PA and PB are also measurement points for total nitrogen concentration. That is, management item measurement units 5 are installed at points PA and PB. However, there are no special scaffolding or other structures installed at point PA to enhance seaweed beds, and there are no seaweed beds there. On the other hand, structures that serve as scaffolding for seaweed beds are installed at point PB. The other points (zones indicated by blanks) are neither measurement points (i.e., no management item measurement units 5 are installed), nor do they have seaweed beds or scaffolding.

[0022] Table 1 below shows an example of the first constraint value, second constraint value, and correction value at point PB for total nitrogen concentration in managed water area 8 (points PA and PB). For example, the water quality target value in managed water areas in the Hyogo Prefecture Nutrient Management Plan (draft) (URL: https: / / www.kankyo.pref.hyogo.lg.jp / jp / info_list / 22742) is set as the range from the lower limit of the prefectural ordinance to the environmental standard value as the desirable nutrient concentration. In Table 1, the lower limit of the prefectural ordinance for total nitrogen in cumulative water area II is set as the first constraint value, and 90% of the environmental standard value is set as the second constraint value (i.e., upper limit). The reason for setting 90% of the environmental standard value as the second constraint value is that the second constraint value in this embodiment is an indicator that determines how to respond assuming that it may be exceeded, while the environmental standard value is assumed not to be exceeded, so a margin of 10% was taken and set to 90%. Since point PB is a point where structures that serve as a foothold for seaweed beds are installed, it is desirable that sufficient nutrients be supplied to the seaweed beds. Therefore, for location PB, the effect of total nitrogen concentration on seaweed beds is increased by using a new corrected first constraint value of 0.23 mg-N / L, which is the sum of the first constraint value (0.20 mg-N / L) and a correction value (0.03 mg-N / L). The second constraint value is set based on values ​​that must be complied with, such as environmental standards, so no correction value is set to relax it. As mentioned above, the correction of the first constraint value, which is the lower limit, i.e., the constraint conditions, is performed in the management item constraint condition setting unit 4.

[0023] [Table 1]

[0024] The descriptions of the embodiments up to this point concern planning, modification, and control. The following describes the control aspects. If the total nitrogen concentration falls below the first constraint value (i.e., the lower limit), seaweed bed growth may not be promoted; therefore, the first constraint value corresponds to a target value related to economic value. On the other hand, if the total nitrogen concentration rises above the second constraint value (i.e., the upper limit), adverse environmental effects such as red tides may occur; therefore, the second constraint value corresponds to a target value related to environmental value. In other words, the total nitrogen concentration, which is a management item in the managed water area 8 of this embodiment, is a management item that has both a first constraint value and a second constraint value that is greater than the first.

[0025] If the measured value of a control item is smaller than the first constraint value related to economic value, the control item for nutrients will be set to "increase," and if it is larger, the control item for nutrients will be set to "maintain." In other words, if the measured value falls below the first constraint value after correction using the correction value, the instruction for the control target value corresponding to that location will be set to "increase." Also, if the measured value exceeds the first constraint value after correction using the correction value, the instruction for the control target value corresponding to that location will be set to "maintain." If the measured value of a control item is smaller than the second constraint value related to environmental value, the control item for nutrients will be set to "maintain," and if it is larger, the control item for nutrients will be set to "reduce." In other words, if the measured value exceeds the second constraint value, the instruction for the control target value corresponding to that location will be set to "reduce."

[0026] Therefore, in the case of a control item having both a first constraint value and a second constraint value that is greater than the first, as in this embodiment, if the measured value of the control item is less than the first constraint value, the control item for nutrients will be "increased". If the measured value of the control item is between the first and second constraint values, the control item for nutrients will be "maintained". If the measured value of the control item is greater than the second constraint value, the control item for nutrients will be "decreased".

[0027] Based on these measured values ​​and constraints (constraints), the correction policies (i.e., correction results) of "increase," "maintain," and "decrease" are calculated by the nutrient control target value correction unit 7. Here, Table 2 shows the measured values ​​of the control items X at the PA location. AThis shows the correction policy for the control target value A of nutrients. Table 3 shows the measured values ​​X of the control items at site PB. B This document outlines the correction policy for the control target value B for nutrient salts.

[0028] [Table 2]

[0029] Location PA is in a normal sea area. Therefore, as shown in Table 2, the measured value X of the total nitrogen concentration of the control item A If it is smaller than the first constraint value, the control target value A for nutrients at point PA, which is the total nitrogen discharge rate, will be "increased". Measured value X of the total nitrogen concentration, which is the control item. A If it is equal to or greater than the first constraint value, then it is "maintained".

[0030] [Table 3]

[0031] On the other hand, location PB is a location where structures that serve as a foothold for seaweed beds are installed, and therefore requires a greater supply of nutrients compared to location PA, which is a normal sea area. For this reason, in this embodiment, the value obtained by adding a correction value to the first constraint value of location PA is treated as the first constraint value of location PB. In this case, the measured value X of the total nitrogen concentration, which is the control item, is used. B If the value is smaller than the first constraint value at point PB, the control target value B for nutrients at point PB, which is the total nitrogen discharge rate (a control item), will be "increased". Measured value X of the total nitrogen concentration (a control item) B If the value is equal to or greater than the first constraint value of point PB, the condition is "maintained".

[0032] There are four possible cases (permutations) for the control target values ​​A and B of nutrients, where the control items are divided into two categories: "increase" and "maintain." Table 4 shows the correction policies for the control target values ​​of nutrients (i.e., the control policies for water treatment plant 1) set for each case of control target value A and control target value B.

[0033] [Table 4]

[0034] As mentioned above, the first constraint value is a constraint value related to economic value, so there is a desire to set it to the highest possible value. Therefore, as shown in Table 4, the nutrient control target value correction unit 7 sets the correction policy for the nutrient control target value to "maintain" only when both the nutrient control target value A and the nutrient control target value B are "maintained" (Case 4). If either or both are "increased" (Cases 1-3), the nutrient control target value correction unit 7 sets the correction policy for the nutrient control target value to "increase".

[0035] Table 5 shows an example of how to calculate the correction value when the correction policy for the control target value of nutrients is "increase". Here, the management item is total nitrogen concentration, and the control item is total nitrogen discharge. In the example shown in Table 5, the correction amount (correction value) for the control target value of nutrients is determined based on the difference Z between the first constraint value and the measured value X. In this example, if the difference is greater than 0, i.e., if the economic value is being impaired, the total nitrogen discharge, which is a nutrient, is increased to promote the growth of seaweed beds. The correction of this correction amount (correction value) for the control target value of nutrients is performed by the nutrient control target value setting unit 3 based on the correction policy (correction result) described above. By adjusting the target values ​​for nutrient levels to increase them in this way, the growth of seaweed beds can be promoted.

[0036] [Table 5]

[0037] In this embodiment, total nitrogen concentration was chosen as the nutrient control item, but ammonia nitrogen concentration, nitrate nitrogen concentration, nitrite nitrogen concentration, organic nitrogen concentration, total phosphorus concentration, phosphate phosphorus concentration, organic phosphorus concentration, etc., or a combination of several of these may also be used. Any of these can be used to suitably control nutrients at point PB in the managed water area 8. It is preferable that these control items have a first constraint value and a second constraint value arbitrarily determined considering economic and environmental value.

[0038] In this embodiment, the management item with the first constraint value relates to economic value. In this embodiment, total nitrogen concentration was chosen as the management item with the first constraint value, but the target ecosystem could be a seagrass bed, specifically a seagrass bed, and its distribution area could also be used. In other words, it could be the distribution area of ​​the target ecosystem. Furthermore, the management items in the managed water area 8 could be other than the distribution area of ​​the target ecosystem, such as the absorption coefficient of the target ecosystem, wet weight per unit area, blue carbon retention rate, blue carbon amount, or a combination of several of these. In this case, it is preferable that these management items have a first constraint value arbitrarily determined considering economic value. This ensures economic value. In addition, the target ecosystems may also include, besides seagrass beds (eelgrass beds), eelgrass, dwarf eelgrass, Japanese dwarf eelgrass, Ryukyu dwarf eelgrass, seaweed beds (garamo beds), red seaweed, sawtooth seaweed, sargassum, Sargassum, Sargassum, Sargassum, kelp beds, kelp beds, kelp beds, narrow-leaved kelp, kelp beds, Ecklonia cuneata, Ecklonia serrata, Ecklonia kelp, Ecklonia sericea

[0039] In this embodiment, point PB is defined as a location where a structure that serves as a foothold for seaweed beds is installed, but any location that influences the growth of seaweed beds is acceptable. Point PB may be, for example, a location near a seaweed bed that corresponds to the upstream area where currents flow into the seaweed bed, a location where fish that increase as a result of seaweed bed growth gather (a location where a large amount of plankton, which serves as food for fish, is needed, and therefore a large amount of nutrients are needed), or a location empirically selected as necessary to enrich the ecosystem. Therefore, the location set in the managed water area environmental classification setting unit 6 should be a location where a structure that serves as a foothold for seaweed bed growth exists and / or within the area of ​​influence thereof. In this way, the ecosystem in that location and area of ​​influence can be enriched.

[0040] Regarding the frequency of correction based on measured values ​​of the management items in this embodiment (i.e., the frequency of correction of the control target value by the nutrient control target value correction unit 7), since the target is ecosystem growth, short-term frequencies such as hourly or daily may be acceptable, but it is preferable to monitor the average trend at medium- to long-term frequencies such as weekly, monthly, seasonal, or yearly, and reflect this in the correction. In this way, long-term growth promotion or growth inhibition effects can be obtained. From this viewpoint, it is more preferable that the frequency of correction of the control target value by the nutrient control target value correction unit 7 be, for example, at most once a month.

[0041] In this embodiment, it is preferable to simultaneously display the measured values ​​from the control item measurement unit 5 and the control target values ​​for nutrients on the display screen. In this case, the nutrient items for which the control target values ​​for nutrients are corrected may be distinguished so that the items to be increased or decreased can be visually confirmed.

[0042] In this embodiment, a table with predetermined numerical values ​​was used as the correction method, but a function format may also be used, or the results of a simulation that calculates the relationship between the measured value and the correction value of the control target value of nutrients may be used.

[0043] In this embodiment, the control item targeted by the nutrient control target value setting unit 3 is set to total nitrogen discharge, but it may also be set to ammonia nitrogen discharge, nitrate nitrogen discharge, nitrite nitrogen discharge, organic nitrogen discharge, total phosphorus discharge, phosphate phosphorus discharge, organic phosphorus discharge, or a combination of several of these. Also, in this embodiment, the discharge is set as the product of flow rate and concentration, but it may also be set to concentration or flow rate.

[0044] Nutrients can be broadly classified into nitrogen-based (total nitrogen, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, organic nitrogen) and phosphorus-based (total phosphorus, phosphate phosphorus, organic phosphorus). The discharge rate from water treatment plant 1 and the concentration measured after reaching the controlled water area 8 show a positive correlation for both nitrogen-based and phosphorus-based nutrients, suggesting that nitrogen-based and phosphorus-based nutrients are independent of each other. In this embodiment, the control item was total nitrogen discharge rate and the management items were total nitrogen concentration and nitrogen-based nutrients. However, if the control item were total phosphorus discharge rate, the management items would be phosphorus-based nutrients such as total phosphorus concentration and phosphate concentration.

[0045] Furthermore, in this embodiment, pre-specified values ​​were used for the first constraint value and the correction value, but these values ​​may also be predicted values ​​based on past performance data, measurement history, or simulation results related to seaweed bed cultivation. In that case, the difference between the first constraint value and the predicted value of the measurement item will arise due to changes in environmental conditions or differences in assumed coefficients, and based on this, the nutrient control target value setting unit 3 will correct the control target value of the nutrient item.

[0046] In this embodiment, an inner bay is used as an example for the managed water area 8 (sea area), but any water area to which the effluent from the water treatment plant 1 reaches, such as lakes, bays, inner bays, inland seas, or open seas, is acceptable. In this embodiment, a method for correcting the nutrient discharge rate of one water treatment plant 1 has been described, but the nutrient content of the entire watershed, including multiple water treatment plants 1, may also be considered. In that case, the nutrient correction can be applied to the multiple water treatment plants 1 by distributing according to predetermined distribution ratios, distribution ratios based on treatment efficiency, or predetermined load acceptance order. Furthermore, the distribution to multiple series within each water treatment plant 1 can also be applied according to predetermined distribution ratios, distribution ratios based on treatment efficiency, or predetermined load acceptance order. The control items may include indicators related to organic matter, such as biochemical oxygen demand (BOD) and chemical oxygen demand (COD), or indicators related to potassium.

[0047] [Second Embodiment] Next, a second embodiment will be described. The plant operation support system S according to the second embodiment has the same configuration as the first embodiment (see Figure 1). In addition, the plant operation support system S according to the second embodiment manages and controls nutrients in the controlled water area 8 in the same way as the first embodiment (see Figure 2).

[0048] In the second embodiment, the control item targeted by the nutrient control target value setting unit 3 is the total nitrogen discharge rate, the management area 8 is an inner bay, and the control items in the management area 8 are the total nitrogen concentration and the chlorophyll a concentration. Total nitrogen concentration and chlorophyll a concentration are indicators that correlate with phytoplankton concentration. Phytoplankton concentration fluctuates due to factors such as number density, cell density, and species. If total nitrogen concentration, chlorophyll a concentration, and phytoplankton concentration are too high, they can cause environmental damage such as red tides. On the other hand, if total nitrogen concentration, chlorophyll a concentration, and phytoplankton concentration are too low, they can impair the growth of marine ecosystems or result in economic losses due to energy consumption from excessive processing. As described in the first embodiment, the indicator corresponding to the target value related to the latter economic value is the first constraint value. The indicator corresponding to the upper limit related to the former environmental damage is the second constraint value. In this embodiment, total nitrogen concentration and chlorophyll a concentration are management items that have both a first constraint value and a second constraint value that is greater than the first.

[0049] As explained in the first embodiment, if the measured value of a control item is smaller than the first constraint value related to economic value, the control item for nutrients is set to "increase," and if it is larger, the control item for nutrients is set to "maintain." In other words, if the measured value falls below the first constraint value after correction using the correction value, the instruction for the control target value corresponding to that location is set to "increase." Also, if the measured value exceeds the first constraint value after correction using the correction value, the instruction for the control target value corresponding to that location is set to "maintain." If the measured value of a control item is smaller than the second constraint value related to environmental value, the control item for nutrients will be set to "maintain," and if it is larger, the control item for nutrients will be set to "reduce." In other words, if the measured value exceeds the second constraint value, the instruction for the control target value corresponding to that location will be set to "reduce."

[0050] Therefore, in the case of a control item having both a first constraint value and a second constraint value that is greater than the first, as in this embodiment, if the measured value of the control item is less than the first constraint value, the control item for nutrients will be "increased". If the measured value of the control item is between the first and second constraint values, the control item for nutrients will be "maintained". If the measured value of the control item is greater than the second constraint value, the control item for nutrients will be "decreased".

[0051] Based on these measured values ​​and constraints (constraints), the correction policies (i.e., correction results) of "increase," "maintain," and "decrease" are calculated by the nutrient control target value correction unit 7. Table 6 shows an example of the first constraint value, the second constraint value, and the correction value of the first constraint value at point PB for the total nitrogen concentration and chlorophyll a concentration in managed water area 8 in the second embodiment. As mentioned above, the water quality target values ​​in managed water areas in the Hyogo Prefecture Nutrient Management Plan (draft) are set from the lower limit of the prefectural ordinance to the environmental standard value as desirable nutrient concentrations. In Table 6, the lower limit of the prefectural ordinance for total nitrogen in cumulative water area II is set as the first constraint value, and 90% of the environmental standard value is set as the second constraint value (i.e., upper limit). The reason why 90% of the environmental standard value is set as the second constraint value is that the second constraint value in this embodiment is an indicator that determines how to respond assuming that it may be exceeded, while the environmental standard value is assumed not to be exceeded, so a margin of 10% is taken and set to 90%. In addition, the chlorophyll a concentration used as an indicator of red tide varies depending on the local government, but in some cases 50 μg / L is used as a guideline for red tide determination. In Table 6, 50% of 50 μg / L, i.e., 25 μg / L, was set as the second constraint value. The first constraint value for chlorophyll a concentration was arbitrarily set. The correction value was set to 10% of each upper limit. Since the second constraint value was set based on values ​​that must be observed, such as environmental standards, no correction value was set to relax it.

[0052] [Table 6]

[0053] The descriptions of the embodiments up to this point concern planning, modification, and control. The following describes the control aspects. Table 7 shows an example of a correction policy for nutrient control target values ​​based on measured values ​​of control items. In the example shown in Table 7, there are a total of nine cases, divided into three categories based on total nitrogen concentration (control item 1) and three categories based on chlorophyll a concentration (control item 2). Each cell in Table 7 shows both the correction policy for control item 1 (left side) and the correction policy for control item 2 (right side). For example, if the measured value X (mg-N / L: nitrogen equivalent concentration) of total nitrogen concentration is smaller than the first constraint value, and the measured value Y of chlorophyll a concentration is larger than the second constraint value, the policy for the control target value of total nitrogen discharge, which is a nutrient, is either "increase" or "decrease," which contradicts the policy. In this case, environmental protection is given priority, and the safer approach, i.e., "reduction" rather than "increase," is prioritized. Similarly, if the policies of "increase," "maintain," and "reduction" for the control target values ​​of nutrients are contradictory, the nutrient control target value correction unit 7 prioritizes "reduction" first, then "maintain," and finally "increase." In other words, if the measured value exceeds the second constraint value, the nutrient control target value correction unit 7 sets the instruction for the control target value corresponding to that location to "reduce". If "reduce" is included in the instruction for the control target value at all locations, the nutrient control target value correction unit 7 sets the instruction for the control target value to "reduce".

[0054] [Table 7]

[0055] Table 8 shows an example of a correction calculation method when the total nitrogen concentration and chlorophyll a concentration exceed the second constraint value, and the correction policy for the nutrient control target value is "reduction." The control item is the total nitrogen discharge. In the example shown in Table 8, the correction amount (correction value) for the nutrient control target value is determined based on the difference Z between the second constraint value and the measured value X for both the total nitrogen concentration and the chlorophyll a concentration. In this example, if the difference Z for the total nitrogen concentration is greater than 0.03 mg-N / L, or if the difference Z for the chlorophyll a concentration exceeds 25 μg / L, i.e., the environmental standard value or the red tide detection value, the total nitrogen discharge is reduced as much as possible. The correction of this correction amount (correction value) for the nutrient control target value is performed by the nutrient control target value setting unit 3 based on the correction policy (correction result) described above.

[0056] [Table 8]

[0057] As shown in Table 8, when both the total nitrogen concentration and the chlorophyll a concentration exceed the second constraint value, both policies aim to "reduce total nitrogen discharge as much as possible," thus reducing the control target value for total nitrogen discharge. However, the indicated values ​​may differ. For example, if the measured total nitrogen concentration X is 0.28 mg-N / L (nitrogen equivalent concentration), referring to the second constraint value (0.27 mg-N / L (nitrogen equivalent concentration)) shown in Table 6, the difference Z for total nitrogen concentration becomes 0.01 mg-N / L (nitrogen equivalent concentration). Similarly, if the measured chlorophyll a concentration X is 40 μg / L, referring to the second constraint value (25 μg / L) shown in Table 6, the difference Z for chlorophyll a concentration becomes 15 μg / L. Therefore, as shown in Table 8, the correction value for total nitrogen discharge related to total nitrogen concentration is -500 kg-N / day (nitrogen equivalent mass), while the correction value for total nitrogen discharge related to chlorophyll a concentration is -2000 kg-N / day. In this case, prioritizing environmental protection, the nutrient control target value setting unit 3 adopts a safer direction, i.e., a smaller setting of -2000 kg-N / day.

[0058] Thus, in this embodiment, by considering adjusting the target value of nutrients to increase them for economic value, and at the same time adjusting the target value of nutrients to reduce them in order to suppress environmental damage, it is possible to implement control that balances economics and the environment. In this embodiment, the first and second constraint values ​​are items that indicate an appropriate range for balancing environmental value and economic value. For example, in the case of total nitrogen concentration in this embodiment, if it exceeds the second constraint value, environmental value will be impaired, and if it falls below the first constraint value, it will damage marine ecosystems, potentially leading to a reduction in economic and social value such as a decrease in marine life, a decrease in biodiversity, a reduction in fish catches, a reduction in blue carbon sequestration, and a reduction in the amount of blue carbon credits created.

[0059] In this embodiment, total nitrogen concentration was chosen as the nutrient management item in the managed water area 8, but ammonia nitrogen concentration, nitrate nitrogen concentration, nitrite nitrogen concentration, organic nitrogen concentration, total phosphorus concentration, phosphate phosphorus concentration, organic phosphorus concentration, etc., or a combination of several of these may also be used. Any of these can be used to suitably control nutrients at point PB in the managed water area 8. It is preferable that these management items have a first constraint value and a second constraint value arbitrarily determined considering economic value and environmental value. In this embodiment, chlorophyll a concentration was chosen as the management item related to red tide, that is, as the management item for nutrients in the managed water area 8. However, other items such as phytoplankton cell density, chlorophyll concentration, pheo pigment concentration, fluorescence intensity, plant pigment concentration, seawater color value, reciprocal of transparency, dissolved oxygen saturation, pH, etc., or a combination of several of these may be used. Any of these can be used to suitably control nutrients at point PB in the managed water area 8. Furthermore, in this case, it is preferable that these management items have a second constraint value. Doing so can reduce environmental damage. Both of the above are management items related to eutrophication, and multiple items may be combined as in this embodiment.

[0060] Regarding the frequency of correction of the measured values ​​of the management items in this embodiment, as in the first embodiment, since the target is the growth of the ecosystem, it may be done at short-term intervals such as hours or days, but it is preferable to monitor the average trend at medium- to long-term intervals such as weeks, months, seasons, or years and reflect this in the correction. In this way, a long-term growth suppression effect can be obtained. From this viewpoint, it is more preferable that the frequency of correction of the control target value by the nutrient control target value correction unit 7 be, for example, at most once a month.

[0061] In this embodiment, as in the first embodiment, it is preferable to simultaneously display the measured values ​​from the control item measurement unit 5 and the control target values ​​for nutrients on the display screen. In this case, the nutrient items for which the control target values ​​for nutrients are corrected may be distinguished so that the items to be increased or decreased can be visually confirmed. Furthermore, although the first and second constraint values ​​were considered simultaneously in this embodiment, only the second constraint value may be considered from the viewpoint of mitigating environmental damage.

[0062] In this embodiment, Table 8 shows only the correction calculation method when the correction policy for the control target value of nutrients is "reduction," but the same method can be used when it is "increase." That is, for example, by referring to Table 5, setting "difference Z = first constraint value - measured value X" and the conditions related thereto, and setting the correction value for the control target value of nutrients accordingly, the nutrient control target value setting unit 3 can perform the correction calculation when it is "increase."

[0063] Furthermore, in this embodiment as in the first embodiment, a table with predetermined numerical values ​​was used as the correction method, but a function format may also be used, or the results of a simulation that calculates the relationship between the measured value and the correction value of the control target value of nutrients may be used.

[0064] In this embodiment, the control item targeted by the nutrient control target value setting unit 3 is set to total nitrogen discharge, but it may also be set to ammonia nitrogen discharge, nitrate nitrogen discharge, nitrite nitrogen discharge, organic nitrogen discharge, total phosphorus discharge, phosphate phosphorus discharge, organic phosphorus discharge, or a combination of several of these. Also, in this embodiment, the discharge is set as the product of flow rate and concentration, but it may also be set to concentration or flow rate.

[0065] Nutrients can be broadly classified into nitrogen-based (total nitrogen, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, organic nitrogen) and phosphorus-based (total phosphorus, phosphate phosphorus, organic phosphorus). The discharge rate from water treatment plant 1 and the concentration measured after reaching the controlled water area 8 show a positive correlation for both nitrogen-based and phosphorus-based nutrients, suggesting that nitrogen-based and phosphorus-based nutrients are independent of each other. In this embodiment, the control item was total nitrogen discharge rate and the management items were total nitrogen concentration and nitrogen-based nutrients. However, if the control item were total phosphorus discharge rate, the management items would be phosphorus-based nutrients such as total phosphorus concentration and phosphate concentration.

[0066] On the other hand, phytoplankton concentration and chlorophyll a concentration, which are management parameters related to red tides, increase as a result of the release of both nitrogen-based and phosphorus-based nutrients, which the nutrients use. Therefore, if phytoplankton concentration or chlorophyll a concentration are selected as management parameters, the control parameters may be either nitrogen-based, phosphorus-based, or both.

[0067] In this embodiment, the measurement location for the control item (the location where the control item measurement unit 5 is installed) was assumed to be one location, but there may be multiple locations or multiple depths. Since the growth conditions of marine ecosystems differ depending on the environment, the magnitudes of the first and second constraints may be varied seasonally, yearly, regionally, and at different depths. Here, Table 9 shows an example of the first constraint (left) and second constraint (right) when the control item is total nitrogen concentration. Specifically, Table 9 shows an example of the first constraint (left) and second constraint (right) for total nitrogen concentration at times T1, T2, and T3 at locations L, M, and N. When varying the magnitudes of the first and / or second constraints, the measured values ​​of the control item may be the average of measurements from multiple locations, a predetermined weighted average, or a statistical method such as the most frequent constraint condition (for example, if the most frequent measured values ​​are below the first constraint, then it is considered below the first constraint).

[0068] [Table 9]

[0069] Furthermore, in this embodiment, pre-specified values ​​were used for the first constraint value and the correction value, but these values ​​may also be predicted values ​​based on past performance data, measurement history, or simulation results related to seaweed bed cultivation. In that case, the difference between the first constraint value and the predicted value of the measurement item will arise due to changes in environmental conditions or differences in assumed coefficients, and the nutrient control target value setting unit 3 will correct the nutrient target value of the control item based on this.

[0070] In this embodiment, an inner bay is used as an example for the managed water area 8 (sea area), but any water area to which the effluent from the water treatment plant 1 reaches, such as lakes, bays, inner bays, inland seas, or open seas, is acceptable. In this embodiment, a method for correcting the nutrient discharge rate of one water treatment plant 1 has been described, but the nutrient content of the entire watershed, including multiple water treatment plants 1, may also be considered. In that case, the nutrient correction can be applied to the multiple water treatment plants 1 by distributing according to predetermined distribution ratios, distribution ratios based on treatment efficiency, or predetermined load acceptance order. Furthermore, the distribution to multiple series within each water treatment plant 1 can also be applied according to predetermined distribution ratios, distribution ratios based on treatment efficiency, or predetermined load acceptance order. The control items could be indicators related to organic matter, such as BOD and COD, or indicators related to potassium.

[0071] The plant operation support system S according to the present invention has the configuration described above, and can supply an appropriate amount of nutrients to a specific point (for example, point PB) within the controlled water area 8. Furthermore, in a water treatment plant 1 that treats and discharges wastewater containing nutrients, and where the discharged water flows into the controlled water area 8 (for example, the sea), the plant operation support system S can make the sea area where the discharged water reaches clean and rich, and promote CO2 sequestration.

[0072] Although the plant operation support system S according to the present invention has been described in detail above with reference to embodiments, the present invention is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner and are not necessarily limited to those having all the described configurations. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add a configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with a configuration of another embodiment. [Explanation of Symbols]

[0073] 1. Water treatment plant 2. Monitoring and Control Unit 3. Nutrient Control Target Value Setting Unit 4 Management item constraint setting section 5. Measurement Unit for Control Items 6 Management water area environmental classification department 7. Nutrient Control Target Value Correction Unit 8 Management water area

Claims

1. A nutrient control target value setting unit sets a control target value for the nutrients discharged from one or more water treatment plants that discharge nutrients and allow them to flow into a controlled water area, A control item constraint setting unit sets constraint conditions for control items in the aforementioned controlled water area, A management item measurement unit for measuring management items in the aforementioned managed water area, A water area environmental classification setting unit sets points for correcting constraints on management items in the aforementioned water area, Nutrient control target value correction unit calculates the correction result of the control target value based on the measured value measured by the control item measurement unit and the constraint conditions set by the control item constraint condition setting unit, Equipped with, The nutrient salt control target value setting unit corrects the control target value based on the correction result. A plant operation support system characterized by the following features.

2. The frequency of correction of the control target value by the nutrient control target value correction unit is at most once a month. The plant operation support system according to claim 1, characterized in that

3. The management items in the aforementioned managed water area have a first constraint value, At a point set by the aforementioned managed water area environmental classification setting unit, the correction value of the first constraint value corresponding to that point is set. If the measured value exceeds the first constraint value after correction by the correction value, the instruction for the control target value corresponding to that location is set to "maintain," and if the measured value falls below the first constraint value after correction by the correction value, the instruction for the control target value corresponding to that location is set to "increase." If the instruction for the control target value at all locations is "maintain," the instruction for the control target value shall be "maintain," otherwise it shall be "increase." The plant operation support system according to claim 1, characterized in that

4. The points set in the aforementioned managed water area environmental classification setting unit are locations where structures that serve as a foothold for seaweed bed growth exist and / or within the area of ​​their influence. The plant operation support system according to feature 1.

5. The management items in the aforementioned managed water area have a second constraint value, If the measured value exceeds the second constraint value, the instruction for the control target value corresponding to that location will be set to "reduce". If the instruction for the control target value at all locations includes "reduction," then the instruction for the control target value shall be "reduction." A plant operation support system according to claim 1, characterized in that

6. The control items targeted by the nutrient control target value setting unit are one or more of the following: total nitrogen discharge, ammonia nitrogen discharge, nitrate nitrogen discharge, nitrite nitrogen discharge, organic nitrogen discharge, total phosphorus discharge, phosphate phosphorus discharge, and organic phosphorus discharge. The plant operation support system according to feature 1.

7. The management items in the aforementioned managed water area are one or more of the following: total nitrogen concentration, ammonia nitrogen concentration, nitrate nitrogen concentration, nitrite nitrogen concentration, organic nitrogen concentration, total phosphorus concentration, phosphate phosphorus concentration, and organic phosphorus concentration. The plant operation support system according to feature 1.

8. The management items in the aforementioned managed water area have a first constraint value and a second constraint value. The plant operation support system according to feature 7.

9. The management items in the aforementioned managed water area are one or more of the following: distribution area of ​​the target ecosystem, absorption coefficient, wet weight per unit area, blue carbon retention rate, and blue carbon amount. The plant operation support system according to feature 1.

10. The management items in the aforementioned managed water area have a first constraint value. The plant operation support system according to feature 9.

11. The management items in the aforementioned managed water area are one or more of the following: phytoplankton concentration, chlorophyll concentration, chlorophyll a concentration, pheo pigment concentration, fluorescence intensity, plant pigment concentration, seawater color value, reciprocal of transparency, dissolved oxygen saturation, and pH. The plant operation support system according to feature 1.

12. The management items in the aforementioned managed water area have a second constraint value. The plant operation support system according to feature 11.

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