CN115340173A - Method and device for calculating operation index, and method and device for treating wastewater - Google Patents
Method and device for calculating operation index, and method and device for treating wastewater Download PDFInfo
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Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/006—Regulation methods for biological treatment
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/24—CO2
- C02F2209/245—CO2 in the gas phase
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/38—Gas flow rate
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/06—Nutrients for stimulating the growth of microorganisms
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Molecular Biology (AREA)
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Abstract
When organic wastewater is biologically treated by a biological treatment tank (10), an operation index is calculated from the amount of treatment of gas measured by a gas measurement unit (31) and the water quality measured by a water quality measurement unit (32) on the basis of a relationship (model or relational expression) that is obtained in advance for the amount of treatment (for example, concentration) of gas discharged from water in the biological treatment tank (10), the water quality of water in the biological treatment tank (10), and the water quality of water to be treated that flows into the biological treatment tank (10). The water quality measured for water within the biological treatment tank (10) includes at least one of water temperature, pH, and oxidation-reduction potential (ORP). The operation index is at least one of an organic matter concentration, a nitrogen concentration, a phosphorus concentration, a dissolved oxygen concentration, and an ORP in the water to be treated.
Description
Technical Field
The present invention relates to treatment of organic wastewater by biological treatment, and more particularly to a method and an apparatus for calculating an operation index for biological treatment, a wastewater treatment method, and a wastewater treatment apparatus.
Background
As a wastewater treatment performed before organic wastewater, which is wastewater containing organic substances, is discharged into the environment, biological treatment using microorganisms is widely employed. In the biological treatment, organic wastewater is flowed into a biological treatment tank as treated water. In biological treatment, in order to maintain high decomposition activity of organic substances by microorganisms, it is necessary to optimize environmental conditions such as water temperature and pH in a biological treatment water tank and to add nutrients such as nitrogen, phosphorus, and trace metals. In drainage from factories, nutrients are liable to be insufficient compared with drainage in public sewers into which domestic drainage flows. In particular, in drainage from chemical plants and semiconductor manufacturing plants, a shortage of nutrients required for biological treatment is remarkable. The wastewater treatment method and the wastewater treatment apparatus by biological treatment are also referred to as a biological treatment method and a biological treatment apparatus, respectively.
The amount of the nutrient added to the water to be treated as the organic wastewater is recommended to be proportional to the organic matter concentration in the water to be treated. Assuming that the concentration of organic matter in the water to be treated is represented by Biochemical Oxygen Demand (BOD), a preferable amount of nitrogen (N) and phosphorus (P) added in aerobic treatment, which is wastewater treatment by aerobic microorganisms, is, for example, BOD: n: p =100:5:1. in order to determine the amount of the added nutrient substances, it is necessary to obtain the BOD value of the water to be treated flowing into the biological treatment tank. While BOD measurements are difficult to perform online or for short periods of time, the measurement of Total Organic Carbon (TOC) concentration in water can be performed online. As an example, patent document 1 discloses that the correlation between the TOC concentration and BOD of water to be treated is acquired in advance, the TOC concentration of the water to be treated is monitored by an on-line TOC concentration meter, and then converted into a BOD value, and the amounts of nitrogen and phosphorus added are controlled based on the obtained BOD value. Here, the BOD value is used as an operation index for determining operation conditions such as the amount of nutrient added when biological treatment is performed in the biological treatment tank.
When the amount of the nutrient to be added is controlled based on the TOC concentration measured on-line, the inside of the pipe of the on-line TOC concentration meter may be clogged with suspended matter (SS), oil, biofilm, and the like, and the measured value may become unstable. As a method for estimating the BOD value without using a TOC concentration meter, patent document 2 discloses that when organic wastewater is biologically treated to obtain wastewater, the concentration of carbon dioxide generated by the biological treatment is measured, and the BOD value in the wastewater is estimated based on the carbon dioxide concentration. Patent document 2 also discloses that biological treatment is controlled by using the estimated BOD value as an operation index, for example, by increasing the amount of returned sludge.
The method disclosed in patent document 2 is a method of estimating a BOD value based on a carbon dioxide generation rate generated in biological treatment based on a generation rate of inorganic carbonic acid generated by the biological treatment being proportional to a concentration of organic matter in the discharge water, and adjusting the treatment using the estimated BOD value as an operation index. However, the inorganic carbonic acid in water is carbon dioxide (CO) depending on the pH of the water 2 ) Bicarbonate ion (HCO) 3 - ) And carbonate ion (CO) 3 2- ) And its form is changed, bicarbonate ions and carbonate ions remain in the water, and thus measuring only the carbon dioxide concentration is insufficient to estimate the amount of carbon dioxide produced in the biological treatment. Furthermore, since the solubility of dissolved gas generally depends on the temperature, and the inorganic carbonic acid component remaining in water is also present in the form of carbon dioxide, and the amount thereof depends on the temperature, only carbon dioxide in the gas phase is measuredIt is difficult to accurately estimate the carbon dioxide generation rate in the biological treatment. As a result, it is difficult to obtain an accurate BOD value by the method described in patent document 2, and the method of calculating the BOD value as the operation index is not appropriate.
In the method described in patent document 2, the treatment by the activated sludge method is adjusted by, for example, means for increasing the amount of returned sludge, depending on the BOD value of the wastewater. However, this method estimates the BOD value of the discharged water, not the BOD value of the influent water to be treated, and therefore, a time delay occurs when the treatment by the activated sludge method is adjusted. As a result, the BOD value calculated by the method described in patent document 2 is not appropriate as an operation index. Further, in the method described in patent document 2, for example, the air flow rate is adjusted based on the BOD value of the wastewater. When the ventilation amount is adjusted to be increased, the carbon dioxide generated in the biological treatment is diluted, and it is difficult to accurately estimate the increase or decrease of the carbon dioxide generated in the biological treatment. In this regard, it is also difficult to obtain an accurate BOD value by the method described in patent document 2, and the method of calculating the BOD value as the operation index is not appropriate.
[ Prior art documents ]
[ patent document ]
Patent document 1: japanese patent laid-open No. 2001-334285
Patent document 2: japanese patent laid-open publication No. Sho 54-60765
Disclosure of Invention
Problems to be solved by the invention
As described above, in the method of controlling the amount of the nutrient added by online measurement of the TOC concentration during the biological treatment, the measured value of the TOC concentration may become unstable, and as a result, optimization of the amount of the nutrient added may not be achieved. Further, as described in patent document 2, when the BOD value is estimated from the concentration of carbon dioxide generated by biological treatment, it is difficult to accurately estimate the BOD value, and the amount of the nutrient added cannot be optimized.
The invention aims to provide a drainage treatment method and a drainage treatment device, which can optimize the addition amount of nutrient substances relative to organic drainage when organic drainage is treated by biological treatment.
Another object of the present invention is to provide a calculation method and a calculation device that can quickly estimate an accurate operation index for controlling biological treatment when organic wastewater is treated by biological treatment, and a wastewater treatment method and a wastewater treatment device that execute controlled biological treatment based on the calculated operation index.
Means for solving the problems
The calculation method according to the present invention is a calculation method of an operation index used when organic wastewater is biologically treated by a biological treatment tank, wherein the operation index is calculated from a measurement value of a treatment amount of gas and a measurement value of a water quality of water in the biological treatment tank, based on a relationship obtained in advance for the treatment amount of gas discharged from water in the biological treatment tank, the water quality of water in the biological treatment tank, the treatment amount of gas being at least one of a concentration, a flow rate, a volume, a pressure, and a substance amount, the water quality of water in the biological treatment tank including at least one of a water temperature, a pH, and an oxidation-reduction potential, and the operation index being at least one of an organic matter concentration, a nitrogen concentration, a phosphorus concentration, a dissolved oxygen concentration, and an oxidation-reduction potential.
The wastewater treatment method according to the present invention is a method for biologically treating organic wastewater, in which an operation index is calculated by the calculation method of the present invention, and control is performed in accordance with the calculated operation index, thereby biologically treating water to be treated in a biological treatment tank.
Another wastewater treatment method according to the present invention is a method for biologically treating organic wastewater in a biological treatment tank, the method including: a first measurement step of measuring a carbon dioxide concentration in a gas discharged from water in a biological treatment tank; a second measurement step of obtaining 1 or more measurement values relating to the quality of water in the biological treatment tank; and a control step of controlling the amount of the nutrient to be added to the organic wastewater on the basis of the measured value of the carbon dioxide concentration obtained in the first measurement step and the 1 or more measured values obtained in the second measurement step.
A wastewater treatment method according to the present invention is a method for biologically treating organic wastewater in a biological treatment tank, including: a first measurement step of measuring a concentration of a specific gas in a gas discharged from water in a biological treatment tank; a second measurement step of measuring a flow rate of the gas supplied to the biological treatment tank or a flow rate of the gas discharged from the biological treatment tank; and a control step of controlling the amount of the nutrient added to the organic wastewater based on the measured value of the concentration obtained in the first measurement step and the measured value of the flow rate obtained in the second measurement step.
The calculation device according to the present invention is a calculation device that calculates an operation index used when biological treatment is performed on organic wastewater in a biological treatment tank, and includes: a gas measuring unit that measures a treatment amount of gas discharged from water in the biological treatment tank; a water quality measuring unit that measures the water quality of water in the biological treatment tank; and an operation unit that calculates an operation index from a measurement value in the gas measurement unit and a measurement value in the water quality measurement unit, based on a relationship obtained in advance for a treatment amount of gas discharged from water in the biological treatment tank, a water quality of the water in the biological treatment tank, and a water quality of the water to be treated flowing into the biological treatment tank, the treatment amount of gas being at least one of a concentration, a flow rate, a volume, a pressure, and a substance amount of the gas, the water quality of the water in the biological treatment tank including at least one of a water temperature, a pH, and an oxidation-reduction potential, the operation index being at least one of an organic matter concentration, a nitrogen concentration, a phosphorus concentration, a dissolved oxygen concentration, and an oxidation-reduction potential in the water to be treated.
The wastewater treatment apparatus according to the present invention is an apparatus for biologically treating organic wastewater, and includes: a computing device according to the invention; and an addition unit for adding nutrients to the water to be treated and/or an air diffusion unit for diffusing air into the biological treatment water tank, wherein at least one of the addition unit and the air diffusion unit is controlled according to the calculated operation index.
Another wastewater treatment apparatus according to the present invention includes: a biological treatment tank for biologically treating organic wastewater; an addition unit that adds a nutrient to the organic wastewater; a first measurement unit having a first sensor that measures a carbon dioxide concentration in a gas discharged from water in the biological treatment water tank; a second measurement unit that acquires 1 or more measurement values related to the water quality of the water in the biological treatment tank; and a control unit that controls the amount of the nutrient added by the addition unit based on the carbon dioxide concentration value obtained by the first measurement unit and the 1 or more measurement values obtained by the second measurement unit.
Still another wastewater treatment apparatus according to the present invention includes: a biological treatment tank for biologically treating organic wastewater; an addition unit that adds a nutrient to the organic wastewater; a first measurement unit that measures a concentration of a specific gas in a gas discharged from water in the biological treatment tank; a second measurement unit that measures a flow rate of the gas supplied to the biological treatment tank or a flow rate of the gas discharged from the biological treatment tank; and a control unit that controls the amount of the nutrient added by the addition unit based on the measurement value of the concentration obtained by the first measurement unit and the measurement value of the flow rate obtained by the second measurement unit.
Drawings
Fig. 1 is a diagram showing a wastewater treatment apparatus according to a first embodiment of the present invention.
Fig. 2 is a diagram showing another example of the wastewater treatment apparatus according to the first embodiment.
Fig. 3 is a diagram showing still another example of the wastewater treatment apparatus according to the first embodiment.
Fig. 4 is a diagram showing a wastewater treatment apparatus according to a second embodiment.
Fig. 5 is a diagram showing another example of the wastewater treatment apparatus according to the second embodiment.
Fig. 6 is a diagram showing still another example of the wastewater treatment apparatus according to the second embodiment.
Fig. 7 is a diagram showing a wastewater treatment apparatus according to a third embodiment including a computing device according to the present invention.
Fig. 8 is a flowchart showing a calculation process of the operation index.
Fig. 9 is a diagram showing an example of the structure of the database.
Fig. 10 is a diagram showing another example of the wastewater treatment apparatus according to the third embodiment.
Fig. 11 is a diagram showing still another example of the wastewater treatment apparatus according to the third embodiment.
Detailed Description
Next, an embodiment of the present invention will be described with reference to the drawings.
The present invention relates to a technique for decomposing and removing organic substances in water to be treated, which is organic wastewater, by performing biological treatment using microorganisms on the water to be treated. The organic wastewater to be treated in the present invention is not particularly limited as long as it is an organic wastewater to which a biological treatment can be applied, and examples thereof include wastewater discharged from public sewers, wastewater discharged from various plants such as food plants, chemical plants, semiconductor manufacturing plants, liquid crystal manufacturing plants, and pulp factories, and wastewater discharged from business places in other fields than these. In drainage from a civil factory, nutrients required to maintain the decomposition activity of microorganisms used for biological treatment at a high level are likely to be insufficient as compared with drainage from a public sewer, and in particular, in drainage from a chemical factory, a semiconductor manufacturing factory, or a liquid crystal manufacturing factory, the shortage of nutrients is significant. When an external organic source such as methanol is added to inorganic nitric acid wastewater (or inorganic nitrous acid wastewater) containing no organic substance to perform denitrification treatment, wastewater to which the external organic source is added is also an organic wastewater to be treated in the present invention. The biological treatment in the present invention includes aerobic treatment, anaerobic treatment, denitrification treatment, and the like, and these biological treatments are performed by an activated sludge process, a membrane-separated activated sludge process (MBR), a fluidized bed or fixed bed biofilm process, a granulation process, or the like.
[ first embodiment ]
Fig. 1 shows a wastewater treatment apparatus according to a first embodiment of the present invention. The wastewater treatment apparatus shown in fig. 1 includes a fluidized-bed biological treatment tank 10 for storing water to be treated as organic wastewater and performing biological treatment of the organic wastewater under aerobic conditions. The treated water from which organic substances are decomposed and removed by the biological treatment is discharged from the biological treatment tank 10. The biological treatment water tank 10 is filled with carriers 11, and a gas diffusing device 12 for supplying oxygen, that is, blowing air into the biological treatment water tank 10 for ventilation is provided at the bottom of the biological treatment water tank 10. An inlet pipe 13 for supplying the water to be treated to the biological treatment tank 10 is connected to the biological treatment tank 10. A gas pipe 14 for supplying air to the air diffusing device 12 is connected to the air diffusing device 12, and a blower 15 for supplying air is provided in the gas pipe 14. Examples of the carrier 11 that can be used here include a plastic carrier, a sponge-like carrier, and a gel-like carrier, and among these, a sponge-like carrier is preferably used from the viewpoint of cost and durability. The biological treatment tank 10 may be provided with a stirring device for stirring the carriers 11.
In the biological treatment, nutrients are required for the microorganisms to maintain their decomposition activity and to grow, and if the nutrients in the water to be treated are insufficient, the nutrients need to be added to the water to be treated in the biological treatment tank 10 or before the biological treatment tank 10. In the wastewater treatment apparatus of the first embodiment, a nutrient storage tank 21 for storing a solution of a nutrient (i.e., a nutrient solution) is provided, and the nutrient storage tank 21 and the inlet pipe 13 are connected via a nutrient solution pipe 22. A pump 23 for supplying the nutrient solution is provided in the nutrient solution pipe 22. Therefore, in this wastewater treatment apparatus, the nutrient can be added to the organic wastewater that flows through the inlet pipe 13 and is supplied to the biological treatment tank 10, and the amount of the nutrient added to the organic wastewater can be controlled by controlling the pump 23. The nutrients are roughly classified into nutrient salts containing nitrogen and phosphorus, and trace elements which are required in a smaller amount than nitrogen and phosphorus. The microelements include alkali metals such as sodium, potassium, calcium and magnesium, and metals such as iron, manganese and zinc. As the nitrogen source, urea or ammonium salt can be used. As the phosphorus source, phosphoric acid or a phosphate can be used.
In the wastewater treatment apparatus of the first embodiment, the amount of the added nutrient substance is controlled based on the carbon dioxide concentration in the gas discharged from the water in the biological treatment tank 10 by the biological treatment and the BOD concentration of the water to be treated calculated from 1 or more measurement values relating to the water quality of the water in the biological treatment tank 10. Therefore, the biological treatment tank 10 is provided with: a carbon dioxide concentration sensor 31 that measures the concentration of carbon dioxide in the gas discharged from the water in the biological treatment water tank 10; and a water quality measuring unit 33 for measuring water quality for 1 or more items. The biological treatment water tank 10 is covered with the cover 16, and the carbon dioxide concentration sensor 31 is provided in a gas phase portion in the biological treatment water tank 10, a pipe connected to the gas phase portion, and the like. Since it is necessary to avoid condensation on the carbon dioxide concentration sensor 31, even when the moisture separator is provided in the pipe, the moisture separator may be provided at a position immediately before the carbon dioxide concentration sensor 31 while keeping the pipe warm. Further, a desulfurization device or the like for removing corrosive gas may be disposed. In the case where the biological treatment tank 10 is an open system, in order to reduce the influence of the external air in the measurement result, a tubular pipe or the like can be inserted below the water surface while minimizing the open portion of the upper portion of the biological treatment tank 10, and the carbon dioxide concentration sensor 31 can be disposed at a position above the water surface in the pipe. As the carbon dioxide concentration sensor 31, for example, an electrochemical or semiconductor sensor can be used, and a sensor based on a non-dispersive infrared absorption method (NDIR) is particularly preferably used. The measurement of the carbon dioxide concentration can be performed manually (manual) or online.
The water quality of the water in the biological treatment tank 10 is measured by the water quality measuring unit 33, and examples thereof include pH (hydrogen ion concentration index), water temperature, dissolved oxygen concentration (DO), oxidation-reduction potential (ORP), conductivity, turbidity, and the like. The water quality measuring unit 33 is configured to be capable of measuring 1 or more items. It is well known that the form of inorganic carbonic acid in water changes to CO depending on pH 2 ，HCO 3 - ，CO 3 2- Thus, it is believed that the pH and water discharge from the biological treatment tank 10 by biological treatmentThe carbon dioxide concentration in the emitted gas is particularly strongly correlated. Further, since the solubility water temperature of carbon dioxide changes according to the water temperature, the water temperature also has a large correlation with the carbon dioxide concentration in the gas discharged from the water in the biological treatment tank 10. In the first embodiment, the measured value including the concentration of carbon dioxide discharged by biological treatment is used instead of measuring the BOD of the water to be treated, and the amount of the added nutrient substance is controlled, and therefore, the items measured by the water quality measuring unit 33 preferably include the pH and the water temperature. The measurement in the water quality measuring section 33 may be performed manually or online.
Although there are on-line TOC concentration meters that measure the Total Organic Carbon (TOC) concentration in water on-line, the on-line TOC concentration meters have thin piping to introduce a small amount of sample water into the measuring apparatus, and are prone to clogging, and the measured value is unstable. On the other hand, since the carbon dioxide concentration sensor 31 performs measurement without contacting water, the stability of the measurement value is very high. Further, since the water quality measuring unit 33 for measuring pH, water temperature, and the like is also a sensor in a form immersed in the biological treatment tank 10, the stability of the measured value is high.
Next, control of the amount of the nutrient added in the wastewater treatment apparatus shown in fig. 1 will be described. It is recommended that the amount of nutrients (nutrient salts and trace metals) added to the water to be treated is proportional to the organic matter concentration in the water to be treated, and preferably proportional to BOD. For example, the amounts of nitrogen (N) and phosphorus (P) added in the aerobic treatment are preferably set to BOD: n: p =100:5:1. in the first embodiment, the BOD of the water to be treated is not measured by an on-line TOC concentration meter or the like, but instead, the carbon dioxide concentration in the gas discharged from the water in the biological treatment tank 10 by the biological treatment and the water quality of the water in the biological treatment tank 10 are measured. Then, the BOD value of the water to be treated is calculated from the measured value of the carbon dioxide concentration and the measured values of 1 or more units related to the water quality, and the amount of the nutrient to be added is determined based on the calculated BOD value. First, in the first embodiment, a combination of the carbon dioxide concentration measured by the carbon dioxide concentration sensor 31 and the measurement value obtained by the water quality measurement unit 33 is used as an input value (Xn), the BOD concentration of the water to be treated corresponding to the input value (Xn) is used as an output value (Yn), and a model (or a relational expression) is created after a certain number (for example, several tens to several hundreds of sets) of combinations of the input value and the output value are acquired in advance. Once the model is created, a combination of the measured value of the carbon dioxide concentration measured by the carbon dioxide concentration sensor 31 and the measured value obtained by the water quality measuring unit 33 is then input to the model, and as a result, the pump 23 is driven based on the BOD concentration value output from the model to control the presence or absence of addition of nutrients to the water to be treated and the amount of addition. In order to perform such control, the wastewater treatment apparatus includes a control device 40, and the control device 40 holds the created model, calculates a BOD concentration value of the water to be treated by applying the carbon dioxide concentration value obtained by the carbon dioxide concentration sensor 31 and the measurement value obtained by the water quality measuring unit 33 to the model, and controls the start/stop and flow rate of the pump 23 based on the BOD concentration value.
Next, creation of a model in the first embodiment will be explained. When an input value is input, a model that outputs the BOD concentration of the water to be treated corresponding to the input value as an output value can be created using various regression analyses, for example. In particular, if a model is created by supervised learning using a neural network technique, the accuracy of controlling the amount of addition of the nutrient substance is improved. The carbon dioxide concentration obtained by the carbon dioxide concentration sensor 31 may vary depending on the structure and size of the biological treatment tank 10, the size of the gas phase portion in the biological treatment tank 10, the type of biological treatment, and the like, and therefore a model may be set for each biological treatment tank 10. Further, since there is a possibility that the relationship between the BOD of the water to be treated and the measured carbon dioxide concentration and pH may vary depending on the type or origin of the water to be treated as the organic wastewater, it is also possible to prepare models for each type or origin of the water to be treated, and select a model for controlling the amount of the nutrient to be added depending on the type or origin of the water to be treated from the thus prepared models.
In the wastewater treatment apparatus shown in FIG. 1, air is blown into the biological treatment water tank 10, but carbon dioxide is usually contained in an amount of about 400ppm in the atmosphere. When measuring the carbon dioxide concentration to estimate the amount of carbon dioxide produced by the biological treatment, the amount of carbon dioxide originally contained in the blown air needs to be taken into account. In the case where the fluctuation in the amount of carbon dioxide in the blown air is small, since the contribution of carbon dioxide contained in the blown air is already contained in the model created as described above, the amount of addition of the nutrient can be determined using the model without measuring the carbon dioxide concentration in the blown air. However, when the concentration of carbon dioxide in the air to be blown varies, for example, when air mixed with exhaust gas from a boiler in a plant is blown, the amount of the nutrient to be added needs to be determined by modifying the carbon dioxide concentration in the gas to be blown into the biological treatment tank 10. Fig. 2 shows the wastewater treatment apparatus thus modified in accordance with the concentration of carbon dioxide blown into the biological treatment tank 10.
The wastewater treatment apparatus shown in fig. 2 is different from the wastewater treatment apparatus shown in fig. 1 in that a carbon dioxide concentration sensor 35 is provided in the gas pipe 14 at a position on the outlet side of the blower 15 in order to measure the carbon dioxide concentration in the blown air. The measurement value of the carbon dioxide concentration sensor 35 provided in the gas pipe 14 is also sent to the control device 40. The control device 40 calculates the difference between the measurement value of the carbon dioxide sensor 31 and the measurement value of the carbon dioxide sensor 35, calculates the BOD concentration value of the water to be treated by applying the difference and the measurement value obtained by the water quality measuring unit 33 to the model, and controls the pump 23 based on the BOD concentration value.
In the wastewater treatment, a plurality of biological treatment water tanks for performing biological treatment are connected in series, and treated water discharged from a preceding biological treatment water tank is introduced into a next biological treatment water tank, and biological treatment is performed in each biological treatment water tank to obtain treated water with highly removed organic matter. Fig. 3 shows a wastewater treatment apparatus in which a plurality of biological treatment tanks 10 for performing biological treatment are provided in series, i.e., in multiple stages. Preferably, when the biological treatment tank 10 is provided in a plurality of stages of 2 or more, the concentration of carbon dioxide in the gas discharged from the biological treatment tank is measured in the biological treatment tank 10 at the top stage, 1 or more measurement values relating to the water quality of the water in the biological treatment tank 10 are acquired, the BOD concentration value of the water to be treated is calculated, and the amount of the nutrient added to the water to be treated supplied to the biological treatment tank 10 at the top stage is controlled based on the BOD concentration value. Therefore, in the wastewater treatment apparatus shown in fig. 3, the carbon dioxide concentration sensor 31 and the water quality measuring unit 33 are provided in the first-stage biological treatment tank 10, and the nutrient solution from the nutrient storage tank 21 is added to the water to be treated in the inlet pipe 13 connected to the first-stage biological treatment tank 10. The controller 40 calculates a BOD concentration value of the water to be treated from the measured values of the carbon dioxide sensor 31 and the water quality measuring unit 33, and controls the pump 23 for supplying the nutrient solution based on the BOD concentration value.
When the biological treatment tanks 10 are provided in series at 2 or more stages, most of the organic substances are decomposed and removed in the biological treatment tank 10 at the top stage, and therefore, the amount of organic substances to be removed in the biological treatment tanks 10 at the 2 nd and subsequent stages is reduced. Then, the microorganisms that have propagated in the first-stage biological treatment water tank 10 die and disintegrate, and the nutrient substances are eluted again. For these reasons, even if nutrients are not newly added to the water supplied to the biological treatment water tanks 10 of the 2 nd and subsequent stages, biological treatment can be advanced in the biological treatment water tanks 10 of the 2 nd and subsequent stages, and the treatment performance of the entire wastewater treatment apparatus can be maintained.
[ second embodiment ]
Next, a second embodiment of the present invention will be explained. In the second embodiment, organic wastewater is supplied as water to be treated to the biological treatment tank, and in order to optimize the amount of nutrients added to the water to be treated, the concentration of a specific gas in the gas discharged from the water in the biological treatment tank and the flow rate of the gas supplied to the biological treatment tank or the gas discharged from the biological treatment tank are measured without directly measuring the BOD or TOC concentration of the water to be treated. Then, the amount of the nutrient added to the water to be treated is controlled based on the measured value of the concentration of the specific gas and the measured value of the flow rate of the gas. In this case, the organic matter concentration of the water to be treated may be calculated from the measured value of the concentration and the measured value of the flow rate, and the amount of the nutrient to be added to the water to be treated may be controlled based on the calculated organic matter concentration, or the amount of the nutrient to be added to the water to be treated may be controlled based on a value obtained by multiplying the measured value of the concentration and the measured value of the flow rate. Further, the water quality (for example, pH) of the water in the biological treatment tank may be measured, and the amount of the nutrient added to the water to be treated may be controlled based on the measured value of the concentration of the specific gas, the measured value of the flow rate, and the measured value of the water quality.
If the biological treatment is aerobic treatment, the concentration of the specific gas is measured, for example, by the concentration of carbon dioxide generated from water in the biological treatment tank. In the aerobic treatment, generally, the water in the biological treatment tank is subjected to an aeration treatment or a diffusion treatment by providing a blower for air blowing and blowing air or the like into the biological treatment tank, and therefore, the flow rate of the gas may be measured as the flow rate of the air supplied from the blower for air blowing into the biological treatment tank or the entire flow rate of the gas discharged from the biological treatment tank. In the case of performing aerobic treatment using a fluidized bed, a mesh is disposed in the biological treatment tank for separating carriers, and air is blown into the biological treatment tank during cleaning of the mesh. If the biological treatment is an anaerobic treatment, the concentration of the specific gas may be measured, for example, the concentration of methane generated from water in the biological treatment tank, and since the gas is not generally dispersed in the anaerobic treatment, the flow rate of the gas may be measured as the entire flow rate of the gas discharged from the biological treatment tank.
Fig. 4 shows a wastewater treatment apparatus according to a second embodiment. The wastewater treatment apparatus shown in fig. 4 includes a fluidized-bed-type biological treatment tank 10 for storing water to be treated as organic wastewater and performing biological treatment of the water to be treated under aerobic conditions. The treated water from which organic substances are decomposed and removed by the biological treatment is discharged from the biological treatment tank 10. The biological treatment tank 10 shown in fig. 4 is filled with carriers 11, provided with a gas diffusing device 12, and connected to an inlet pipe 13, similarly to the biological treatment tank 10 of the first embodiment shown in fig. 1. The gas pipe 14 is connected to the gas diffusing device 12, and a blower 15 for supplying gas is provided in the gas pipe 14. As the carrier 11, the same carrier as that described in the first embodiment is used. A stirring device for stirring the carrier 11 may be provided in the biological treatment tank 10. Similarly to the wastewater treatment apparatus shown in FIG. 1, a nutrient tank 21 may be provided in the wastewater treatment apparatus shown in FIG. 4, and the nutrient tank 21 and the inlet pipe 13 may be connected via a nutrient solution pipe 22. A pump 23 for supplying the nutrient solution is provided in the nutrient solution pipe 22. As the nutrient substance, the same substance as that described in the first embodiment can be used.
In the wastewater treatment apparatus of the second embodiment, the amount of the nutrient added is controlled based on the carbon dioxide concentration in the gas discharged from the water in the biological treatment tank 10 by the biological treatment and the flow rate of the air supplied to the biological treatment tank 10 for aeration. Therefore, the biological treatment water tank 10 is provided with a carbon dioxide concentration sensor 31 for measuring the concentration of carbon dioxide in the gas discharged from the water in the biological treatment water tank 10, and the gas pipe 14 is provided with an air flow meter 32 for measuring the flow rate of the air flowing therethrough at a position between the blower 15 and the air diffuser 12. The kind and arrangement form of the carbon dioxide concentration sensor 31 are the same as those in the first embodiment. Therefore, the carbon dioxide concentration sensor 31 may be provided with a moisture separator or a desulfurizer.
Next, control of the amount of the nutrient added in the wastewater treatment apparatus shown in fig. 4 will be described. As described above, it is recommended that the amount of the nutrients (nutrient salts and trace metals) added to the water to be treated is proportional to the organic matter concentration in the water to be treated, and preferably proportional to BOD. For example, the amounts of nitrogen (N) and phosphorus (P) added in the aerobic treatment are preferably set to BOD: n: p =100:5:1. in the second embodiment, instead of measuring the BOD of the water to be treated by an on-line TOC concentration meter or the like, the carbon dioxide concentration in the gas discharged from the water in the biological treatment tank 10 by the biological treatment and the flow rate (i.e., the air volume) of the air supplied to the biological treatment tank 10 for air dissipation are measured. Then, the BOD value of the water to be treated is calculated from the measured value of the carbon dioxide concentration and the measured value of the flow rate of the air, and the amount of the nutrient to be added is determined based on the calculated BOD value. For this purpose, first, in the second embodiment, a combination of the carbon dioxide concentration measured by the carbon dioxide concentration sensor 31 and the measured value of the air volume obtained by the air volume meter 32 is used as an input value (Xn), the BOD concentration of the water to be treated corresponding to the input value (Xn) is used as an output value (Yn), and a model (or a relational expression) is created on the basis of a predetermined number (for example, several tens to several hundreds sets) of combinations of input values and output values which are acquired in advance. In this case, instead of using the combination of the measured values of the carbon dioxide concentration and the air volume as the input value (Xn), a value obtained by multiplying the measured value of the carbon dioxide concentration and the measured value of the air volume (that is, a product) may be used as the input value (Xn).
Once the model is created, a combination of the measured value of the carbon dioxide concentration measured by the carbon dioxide concentration sensor 31 and the measured value of the air volume obtained by the air volume meter 32 is then input to the model, and as a result, the pump 23 is driven based on the BOD concentration value output from the model to control the presence or absence of addition of the nutrient substance to the water to be treated and the amount of addition. In order to perform such control, the wastewater treatment apparatus includes a control device 40, and the control device 40 holds the created model, calculates a BOD concentration value of the water to be treated by applying the carbon dioxide concentration value obtained by the carbon dioxide concentration sensor 31 and the measurement value obtained by the air gauge 32 to the model, and controls the start/stop and the flow rate of the pump 23 based on the BOD concentration value. Further, although the BOD concentration is used for creating the model, the created model itself is considered to be a model in which the measured value of the carbon dioxide concentration and the measured value of the air volume are input and the amount of the added nutrient substance is directly output, and therefore, once the model is created, it is not necessary to explicitly calculate the BOD concentration value from the measured value of the carbon dioxide concentration and the measured value of the air volume, and it is possible to determine the optimum amount of the added nutrient substance.
Next, the creation of the model will be explained. When an input value is input, a model that outputs the BOD concentration of the water to be treated corresponding to the input value as an output value can be created using, for example, various regression analyses. In particular, when a model is created by supervised learning using a neural network technique, the accuracy of controlling the amount of addition of the nutrient substance is improved. The carbon dioxide concentration obtained by the carbon dioxide concentration sensor 31 may vary depending on the structure and size of the biological treatment tank 10, the size of the gas phase portion in the biological treatment tank 10, the type of biological treatment, and the like, and the air volume of the air supplied to the biological treatment tank 10 for air dissipation may vary depending on the structure and size of the biological treatment tank 10, and therefore, the model may be set for each biological treatment tank 10. Further, since there is a possibility that the relationship between the BOD of the water to be treated and the measured carbon dioxide concentration and the air volume may vary depending on the type or the place of the water to be treated, it is also possible to prepare models for each type or place of the water to be treated, and select a model for controlling the amount of the nutrient to be added depending on the type or the place of the water to be treated from the models prepared in this manner.
In the wastewater treatment apparatus shown in fig. 4, the air flow meter 32 is provided in the gas pipe 14 to measure the flow rate of air supplied to the biological treatment tank 10 through the gas pipe 14, that is, the air volume, but instead of measuring the flow rate of air supplied to the biological treatment tank 10, the flow rate of gas discharged from the biological treatment tank 10 may be measured. When measuring the flow rate of the gas discharged from the biological treatment tank 10, the air flow meter 32 may be provided in a pipe communicating with the inside of the biological treatment tank 10 to discharge the gas to the outside when the biological treatment tank 10 is completely covered with the cover 16. In the case where the biological treatment tank 10 is an open system, in order to reduce the influence of the outside air in the measurement result, it is possible to insert a tubular pipe or the like below the water surface while minimizing the open portion of the upper portion of the biological treatment tank 10, and to install the air gauge 32 in the pipe.
In order to control the amount of nutrients added to the water to be treated, it is also conceivable to measure the organic matter concentration in the water on-line using an on-line TOC concentration meter, but the on-line TOC concentration meter is provided with a thin pipe for introducing a small amount of sample water into the measuring apparatus, and is liable to cause clogging, and the measured value is unstable. In contrast, since the carbon dioxide concentration sensor 31 performs measurement without contacting water, the stability of the measurement value is very high. In addition, the gas flow rate can be stably measured. Therefore, in the wastewater treatment apparatus of the second embodiment, the optimum value of the nutrient for the amount of the added nutrient to the water to be treated can be stably obtained without directly measuring the organic matter concentration in the water to be treated.
Fig. 5 shows another example of the wastewater treatment apparatus according to the second embodiment. The wastewater treatment apparatus shown in FIG. 5 is a wastewater treatment apparatus in which a water quality measuring unit 33 for measuring the water quality of the water in the biological treatment tank 10 is provided in the wastewater treatment apparatus shown in FIG. 4, and the measurement result in the water quality measuring unit 33 is also sent to the control device 40. The water quality items measured by the water quality measuring unit 33 include at least pH, and may be water temperature or the like in addition to pH. In this case, the model used in the wastewater treatment apparatus is a model in which a combination of the carbon dioxide concentration measured by the carbon dioxide concentration sensor 31, the measurement value of the air volume obtained by the air volume meter 32, and the measurement value of the water quality (particularly, pH) measured by the water quality measurement unit 33 is used as an input (Xn), and the BOD concentration of the water to be treated corresponding to the input value (Xn) is used as an output value (Yn), and is created in the same manner as the above-described model. The controller 40 calculates a BOD concentration value of the water to be treated by applying the carbon dioxide concentration measured by the carbon dioxide concentration sensor 31, the measured value of the air volume obtained by the air volume meter 32, and the measured value of the water quality (particularly, pH) measured by the water quality measuring unit 33 to a model, and controls the pump 23 based on the BOD concentration value.
As described above, even if the organic matter concentration in the water to be treated is the same, the carbon dioxide concentration in the gas discharged from the water in the biological treatment tank 10 may vary depending on the pH. In the wastewater treatment apparatus shown in fig. 5, the amount of the nutrients to be added is controlled in consideration of the pH of the water in the biological treatment tank 10, and therefore, the amount of the nutrients to be added can be optimized regardless of the pH of the water to be treated. The solubility of carbon dioxide in water depends on the water temperature, but if the solubility of carbon dioxide changes, the concentration of carbon dioxide in the gas discharged from the water in biological treatment tank 10 also changes. Therefore, when there is a water temperature fluctuation in the biological treatment tank 10, the water temperature is measured in addition to the pH in the water quality measuring unit 33, and the amount of the nutrient to be added can be controlled based on the water temperature in addition to the carbon dioxide concentration, the air volume, and the pH.
In the second embodiment, a plurality of biological treatment water tanks for performing biological treatment may be connected in series to obtain treated water from which organic substances are highly removed. Fig. 6 shows a wastewater treatment apparatus for performing aerobic treatment-based wastewater treatment in the same manner as the wastewater treatment apparatus shown in fig. 4 and 5, and the wastewater treatment apparatus is provided with a plurality of biological treatment tanks 10 connected in series, i.e., in multiple stages. When the biological treatment tank 10 is provided with a plurality of stages of 2 stages or more, the concentration of carbon dioxide in the gas discharged from the biological treatment tank is measured in the biological treatment tank 10 at the front stage, the air volume of the air supplied to the biological treatment tank is measured, the BOD concentration value of the water to be treated is calculated from the carbon dioxide concentration and the air volume, and the amount of nutrient added to the water to be treated supplied to the biological treatment tank can be controlled based on the BOD concentration value. In this case, too, the pH of the water in the first-stage biological treatment water tank 10 can be measured, and the amount of nutrients added to the water to be treated can be controlled based on the carbon dioxide concentration, the air volume, and the pH. Therefore, in the wastewater treatment apparatus shown in fig. 6, the carbon dioxide concentration sensor 31, the air gauge 32, and the water quality measuring unit 33 are provided only in the first-stage biological treatment tank 10, and the nutrient solution from the nutrient storage tank 21 is added to the water to be treated in the inlet pipe 13 connected to the first-stage biological treatment tank 10. The controller 40 calculates a BOD concentration value of the water to be treated from the measurement values of the carbon dioxide sensor 31, the air gauge 32, and the water quality measuring unit 33, and controls the pump 23 for supplying the nutrient solution based on the BOD concentration value.
When the biological treatment tanks 10 are provided in series at 2 or more stages, as described above, biological treatment can be advanced in the biological treatment tanks 10 at 2 and later stages without newly adding nutrients to the water supplied to the biological treatment tanks 10 at 2 and later stages, and the treatment performance of the entire wastewater treatment apparatus can be maintained. Therefore, the measurement of the carbon dioxide concentration, the air volume, and the pH in the biological treatment water tank of the 2 nd or later stage is not required.
According to the first and second embodiments of the present invention described above, in the biological treatment of organic wastewater, the optimum amount of nutrients to be added to the water to be treated as organic wastewater can be stably determined.
[ third embodiment ]
Next, a third embodiment of the present invention will be explained. The third embodiment relates to calculation of an operation index for controlling biological treatment when organic wastewater is biologically treated with microorganisms in a biological treatment tank to decompose and remove organic substances. Fig. 7 shows a wastewater treatment apparatus according to a third embodiment, which includes a calculation device for calculating an operation index.
The wastewater treatment apparatus shown in fig. 7 includes a fluidized-bed biological treatment tank 10 for storing water to be treated and performing biological treatment of the water to be treated under aerobic conditions. In the third embodiment, the water to be treated is organic wastewater flowing into the biological treatment tank 10. The treated water from which the organic matter is decomposed and removed by the biological treatment is discharged from the biological treatment tank 10. As in the case of the first embodiment, the biological treatment tank 10 shown in fig. 7 is filled with carriers 11, and a gas diffusing device 12 for blowing air into the biological treatment tank 10 for supplying oxygen is provided at the bottom of the biological treatment tank 10. An inlet pipe 13 for supplying the water to be treated to the biological treatment tank 10 is connected to the biological treatment tank 10. A gas pipe 14 for supplying air to the air diffusing device 12 is connected to the air diffusing device 12, and a blower 15 for supplying air is provided in the gas pipe 14. Examples of the carrier 11 that can be used here include a plastic carrier, a sponge-like carrier, and a gel-like carrier, and among these, a sponge-like carrier is preferably used from the viewpoint of cost and durability. A stirring device for stirring the carrier 11 may be provided in the biological treatment tank 10.
In the wastewater treatment apparatus shown in fig. 7, an operation index for controlling the biological treatment is calculated based on the treatment amount of the specific gas discharged from the water in the biological treatment tank 10 by the biological treatment and 1 or more measurement values related to the water quality of the water in the biological treatment tank 10. Therefore, the biological treatment tank 10 is provided with: a gas measuring unit 36 that measures a treatment amount of a specific gas discharged from the water in the biological treatment tank 10; and a water quality measuring unit 33 for measuring the water quality of the water in the biological treatment tank 10. The biological treatment tank 10 is covered with the lid 16, and the gas measuring section 36 is provided in a gas phase section in the biological treatment tank 10, a pipe connected to the gas phase section, and the like. Since it is necessary to avoid condensation on the gas measurement unit 36, even when the gas measurement unit is installed in a pipe, the pipe can be kept warm, and the moisture separator can be disposed immediately in front of the gas measurement unit 36. Further, a desulfurization device or the like for removing corrosive gas may be disposed. In the case where the biological treatment tank 10 is an open system, in order to reduce the influence of the external air in the measurement result, a cylindrical pipe or the like is inserted below the water surface so that the open portion of the upper portion of the biological treatment tank 10 can be reduced as much as possible, and the gas measurement unit 36 is disposed at a position above the water surface in the pipe.
As the treatment amount of the specific gas discharged in the biological treatment, for example, the concentration of the specific gas (unit is, for example, ppm or mL/m) 3 ) At least one of the flow rate (unit, for example, mL/h) of the specific gas obtained by multiplying the concentration of the specific gas by the flow rate of the total gas discharged from the water in the biological treatment tank 10 by the biological treatment, the volume (unit, for example, mL) of the gas obtained by multiplying the flow rate by a predetermined time or an integrated time, the partial pressure (unit, for example, pa) of the specific gas calculated from the concentration of the specific gas and the pressure of the gas discharged from the water in the biological treatment tank 10 by the biological treatment, and the like. In addition to the volume and partial pressure, the mass (unit is, for example, kg) and the amount of substance (unit is mol) can be arbitrarily used. Various gases can be considered as gases that can be generated in the biological treatment, but when the biological treatment is an aerobic treatment, it is preferable that the gas measuring section 36 measure the amount of carbon dioxide that is the final product of decomposition of organic matter by the aerobic treatment. In the presence of a catalyst as a dioxygenWhen the amount of carbon conversion to be treated is measured, for example, in the case of measuring the concentration thereof, the gas measuring unit 36 may be an optical, electrochemical, or semiconductor type carbon dioxide concentration sensor, for example, but a sensor based on a non-dispersive infrared absorption method (NDIR) is particularly preferably used. The measurement of the gas throughput can be performed manually (manual) or online. When the flow rate is measured as the gas throughput, the flow rate sensor is not limited to carbon dioxide, and may be an ultrasonic, electromagnetic, coriolis, karman vortex, float, thermal, impeller, or differential pressure flow sensor.
In the third embodiment, as the water quality of the water in the biological treatment water tank 10, items to be measured by the water quality measuring unit 33 include, for example, pH (hydrogen ion concentration index), water temperature, dissolved oxygen concentration (DO), oxidation-reduction potential (ORP), conductivity, turbidity, and the like. The water quality measuring unit 33 is configured to be capable of measuring 1 or more items including at least one of pH, water temperature, and ORP among these items. As described above, it is considered that the pH has a particularly large correlation with the carbon dioxide concentration in the gas discharged from the water in the biological treatment tank 10 by the aerobic treatment, i.e., the biological treatment. Further, since the solubility water temperature of carbon dioxide varies depending on the water temperature, the water temperature is also greatly related to the carbon dioxide concentration in the gas discharged from the water in the biological treatment water tank 10. From ORP and dissolved oxygen concentration, the amount of oxygen and the oxidation-reduction tendency of water in the biological treatment tank 10 can be grasped, and ORP and dissolved oxygen concentration have a large correlation with the concentration of discharged carbon dioxide. The measurement in the water quality measuring unit 33 may be performed manually or online.
Although there are on-line TOC concentration meters that measure the Total Organic Carbon (TOC) concentration in water on-line, the on-line TOC concentration meters have thin piping to introduce a small amount of sample water into the measuring apparatus, and are prone to clogging, and the measured value is unstable. On the other hand, since the carbon dioxide concentration sensor and the gas flow rate sensor perform measurement without contacting water, the stability of the measurement value is very high. Further, the water quality measuring unit 33 for measuring pH, water temperature, ORP, and the like is also a sensor in a form immersed in the biological treatment tank 10, and therefore, the stability of the measurement value is high.
In the wastewater treatment apparatus shown in fig. 7, an operation index relating to treated water, which is water supplied to the biological treatment tank 10, is calculated from a value of the treatment amount of gas measured by the gas measurement unit 36 and a value of the water quality measured by the water quality measurement unit 33. The calculated operation index is used to determine the amount of nutrient substances added to the water to be treated or the water in the biological treatment tank 10, or to determine the amount and flow rate of air and oxygen blown into the biological treatment tank 10, for example. The wastewater treatment device is provided with an arithmetic device 50 for calculating the operation index. Measured values are input to the arithmetic device 50 from the gas measuring unit 36 and the water quality measuring unit 33, respectively, and the arithmetic device 50 calculates an operation index from the measured value in the gas measuring unit 36 and the measured value in the water quality measuring unit 33 based on a predetermined relationship among the treatment amount of the gas discharged from the water in the biological treatment tank 10, the water quality of the water in the biological treatment tank 10, and the water quality of the water to be treated. The predetermined relationship among the gas concentration, the water quality, and the operation index is expressed by a model or a relational expression. The creation of the model and the relational expression will be described later. The operation index calculated by the arithmetic device 50 is an operation index relating to the water to be treated. The operation index relating to the water to be treated is preferably at least one of an organic matter concentration, a nitrogen concentration, a phosphorus concentration, a dissolved oxygen concentration, and an ORP in the water to be treated, and more preferably at least one of a Total Organic Carbon (TOC) concentration, a Biochemical Oxygen Demand (BOD), and a Chemical Oxygen Demand (COD) in the water to be treated. TOC, BOD and COD are all indexes indicating the concentration of organic matter in the water to be treated.
FIG. 8 is a flowchart showing the procedure of a process for determining the organic matter concentration of the water to be treated in the wastewater treatment apparatus shown in FIG. 7. First, at step 101, the gas measuring unit 36 measures the treatment amount (e.g., concentration) of the gas (e.g., carbon dioxide) discharged from the water in the biological treatment tank 10, and at step 102, the water quality measuring unit 33 measures the water quality (e.g., pH, water temperature, or ORP) of the water in the biological treatment tank 10. In fig. 8, it is depicted that step 102 is performed after the execution of step 101, but step 102 may be performed before step 101, or step 101 and step 102 may be performed simultaneously. Then, in step 103, the arithmetic unit 50 calculates an operation index (for example, organic matter concentration) related to the water to be treated by substituting the treated amount of the gas obtained in step 101 and the water quality obtained in step 102 into the model and the relational expression already stored in the arithmetic unit 50.
Next, the creation of a model or a relational expression used in the wastewater treatment apparatus shown in fig. 7 will be described. The model or the relational expression is created by examining in advance the relationship among the amount of gas generated from the water in the biological treatment tank 10, the water quality in the biological treatment tank 10, and the water quality related to the operation index of the water to be treated flowing into the biological treatment tank 10. In order to create the model and the relational expression, the wastewater treatment apparatus shown in fig. 7 is provided with a treated water quality measuring unit 34 for measuring the quality of treated water as an operation index in the inlet pipe 13 for supplying treated water to the biological treatment tank 10. The water quality measured by the treated water quality measuring unit 34 is preferably at least one of an organic matter concentration, a nitrogen concentration, a phosphorus concentration, a dissolved oxygen concentration, and an ORP, and more preferably any of TOC, BOD, and COD, which are organic matter concentrations. The arithmetic device 50 creates a model and a relational expression based on the quality of the treated water measured by the treated water quality measuring unit 34, the measurement value at the gas measuring unit 36 at the time of measuring the quality of the treated water, and the measurement value at the water quality measuring unit 33. A combination of a certain number (for example, several tens to several hundreds of groups) of measured values of the amount of treatment of the gas, measured values of the quality of water in the biological treatment tank 10 measured by the water quality measuring unit 33, and measured values of the quality of treated water measured by the treated water quality measuring unit 34 is obtained, and multiple regression analysis (in the case of deriving a relational expression) or learning of a neural network (in the case of creating a model) is performed based on data of these groups. The amount of gas to be treated and the water quality vary depending on the structure and size of the biological treatment tank 10, the size of the gas phase in the biological treatment tank 10, the type of biological treatment, and the like, and therefore a model and a relational expression may be created for each biological treatment tank 10. Furthermore, since there is a possibility that the relationship between the quality of the water to be treated, the measured treatment amount of the gas, and the quality of the water in the biological treatment tank 10 may vary depending on the type or the place of the water to be treated, a model may be created for each type or place of the water to be treated.
Fig. 9 shows an example of a database storing a set of measured values of the amount of gas treated, measured values of the water quality of water in the biological treatment tank 10, and measured values of the water quality of water to be treated. Here, the carbon dioxide concentration is measured as the amount of gas to be treated, the water temperature and pH are measured as the water quality of water in the biological treatment tank 10, and the TOC concentration is measured as the water quality of water to be treated. By performing multiple regression analysis on such a database, a relational expression for calculating the organic matter concentration as an operation index shown below is obtained.
C＝b 1 X+b 2 Y+b 0
Where C is the organic matter concentration as an operation index, X is the gas concentration as the amount of gas to be treated, Y is the water quality of water in the biological treatment tank 10, and b is 0 、b 1 、b 2 Are constants obtained by multiple regression analysis.
When a model based on a neural network is generated, the neural network may be learned by supervised learning based on the database shown in fig. 9, with the gas treatment amount Xn and the water quality Yn as input values (Xn, yn), and the organic matter concentration Cn as an operation index as an output value (Cn). Using a model based on an appropriately learned neural network provides a more accurate organic matter concentration as an operation index than a relational expression based on multiple regression analysis.
FIG. 10 shows a wastewater treatment apparatus in which a mechanism for adding nutrients to water to be treated is added to the wastewater treatment apparatus shown in FIG. 7. In biological treatment such as aerobic treatment, for example, nutrients are required for microorganisms to grow while maintaining their decomposition activity at a high level, and in the case where nutrients are insufficient in the water to be treated in the biological treatment tank 10, nutrients need to be added to the water to be treated in the biological treatment tank 10 or before the biological treatment tank 10. In the wastewater treatment apparatus shown in fig. 10, a nutrient storage tank 21 for storing a solution of a nutrient (i.e., a nutrient solution) is provided, and the nutrient storage tank 21 and the inlet pipe 13 are connected via a nutrient solution pipe 22. A pump 23 for supplying the nutrient solution is provided in the nutrient solution pipe 22. Therefore, in this wastewater treatment apparatus, nutrients can be added to the water to be treated which flows through the inlet pipe 13 and is supplied to the biological treatment tank 10, and the amount of the nutrients added to the water to be treated can be controlled by controlling the pump 23. As the nutrient substance, the substance described in the first embodiment can be used.
Next, control of the amount of the nutrient added in the wastewater treatment apparatus shown in fig. 10 will be described. It is recommended that the amount of nutrients (nutrient salts and trace metals) added to the water to be treated in the biological treatment tank be proportional to the organic matter concentration in the water to be treated. For example, assuming that BOD is used as an operation index, it is recommended that the amounts of nitrogen (N) and phosphorus (P) added in the aerobic treatment be BOD: n: p =100:5:1. therefore, in the wastewater treatment apparatus shown in fig. 10, the discharge amount and the operation time of the pump 23 are controlled based on the operation index obtained by the arithmetic unit 50, and the presence or absence of addition and the amount of addition of the nutrient to the water to be treated are controlled. Thus, even if the organic matter concentration (for example, BOD) in the water to be treated is not measured, the nutrient can be added to the water to be treated in an optimum amount.
As described in the first embodiment, when the gas is blown into the biological treatment tank 10, the amount of the nutrient to be added needs to be determined by modifying the carbon dioxide concentration in the gas. Fig. 11 shows a wastewater treatment apparatus modified in accordance with the concentration of carbon dioxide blown into the biological treatment tank 10. The wastewater treatment apparatus shown in fig. 11 is the same as the wastewater treatment apparatus shown in fig. 7, but differs from the wastewater treatment apparatus shown in fig. 7 in that a carbon dioxide concentration sensor 35 is provided at a position on the outlet side of the blower 15 in the gas pipe 14 in order to measure the carbon dioxide concentration in the blown air. The measurement value of the carbon dioxide concentration sensor 35 provided in the gas pipe 14 is also sent to the arithmetic device 50. The arithmetic device 50 calculates the difference between the measurement value of the carbon dioxide concentration sensor 35 and the measurement value of the gas measurement unit 36, applies the difference and the measurement value obtained by the water quality measurement unit 33 to a model to calculate the BOD of the water to be treated, and controls the pump 23 based on the BOD.
According to the third embodiment of the present invention described above, when the organic wastewater is treated by the biological treatment, the accurate operation index for controlling the biological treatment can be quickly obtained, and thus, for example, when nutrients are added to the water to be treated which is supplied to the biological treatment tank and flows in, the optimal amount of addition based on the operation index can be achieved.
[ examples ]
The present invention will be described in further detail with reference to examples and comparative examples.
Example A and comparative example A
Example a and comparative example a will be described. Example a and comparative example a are examples and comparative examples corresponding to the first embodiment. The examples and comparative examples are distinguished by assigning branch numbers.
[ test conditions A1]
First, the test conditions common to examples A-1, A-2 and A-3 and comparative examples A-1 and A-2 will be described. Biological treatment by aerobic treatment of water to be treated as organic wastewater was carried out using a primary biological treatment tank having a volume of 19L. Aerobic microorganisms are supported on a sponge-like carrier made of a hydrophobic polyurethane resin, and the biological treatment tank is filled with the sponge-like carrier in a bulky volume of 20% relative to the volume of the biological treatment tank. The retention time in the biological treatment tank was set to 18 hours. As the water to be treated, drainage containing isopropyl alcohol was used. The BOD concentration of the water to be treated is about 900mg/L (reference concentration), the nitrogen (N) concentration of the water to be treated is 2mg/L or less, and the phosphorus (P) concentration of the water to be treated is 0.1mg or less. The BOD volume loading at the time of biological treatment is about 1kg/m 3 The water temperature is about 20 ℃ per day, the concentration of Dissolved Oxygen (DO) in the water in the biological treatment water tank is 2mg/L or more, and the pH of the water in the biological treatment water tank is 6.0 to 7.5.
To the water to be treated, nutrient salts (nitrogen (N) and phosphorus (P)) are sufficiently added so that BOD: n: p is 100:5: monitoring a concentration of carbon dioxide discharged from water in the biological treatment tank, a pH of the water in the biological treatment tank, and a concentration of dissolved oxygen. The BOD concentration in the treated water was intentionally varied from 100% of the reference concentration to 30% and 60%, and this monitoring was repeatedly performed. Further, the ability to accurately calculate the BOD concentration of the water to be treated has the same meaning as the accuracy of the nutrient addition control.
Comparative example A-1
The BOD concentration is calculated according to the carbon dioxide concentration, and the determination coefficient R is calculated by unitary regression analysis according to the carbon dioxide concentration and each BOD concentration 2 The result was 0.840.
[ example A-1]
The BOD concentration is calculated from the carbon dioxide concentration and the pH of the water in the biological treatment tank, and the determination coefficient R is calculated by multiple regression analysis for the carbon dioxide concentration, the pH and each BOD concentration 2 The result was 0.991. It is found that the accuracy of calculation of the BOD concentration is significantly improved by using the carbon dioxide concentration and the pH, as compared with the case of using only the carbon dioxide concentration.
[ example A-2]
The BOD concentration is calculated from the carbon dioxide concentration and the pH of the water in the biological treatment tank, and the determination coefficient R is calculated by neural network analysis for the carbon dioxide concentration, the pH and each BOD concentration 2 The result was 0.996. It is found that the calculation accuracy is further improved by using the neural network model.
[ error variance in neural network analysis ]
According to the above test condition A1, the carbon dioxide concentration, pH and dissolved oxygen concentration were monitored. Thus, a plurality of data sets were obtained in which the input was set to the carbon dioxide concentration, pH, and dissolved oxygen concentration, and the output was set to the BOD concentration. Therefore, with respect to all the acquired data sets, a specific one of the data sets is used as test data, and the other data sets are used as training data, and a model is created by neural network analysis, and an error between an output value when the test data is input to the model and an actual measured value of BOD of the water to be treated is obtained. This operation was repeatedly performed on all data sets as cross validation, and the variance of the resulting error was calculated and evaluated. The lower the error variance value, the more appropriate the BOD concentration of the water to be treated can be calculated.
Comparative example A-2
For the data set using only the carbon dioxide concentration as input, the error variance was found, resulting in 290.
[ examples A-3]
With respect to the data set using the carbon dioxide concentration and the dissolved oxygen concentration as inputs, an error variance was obtained, and the error variance was improved to 61. With respect to the data set using the carbon dioxide concentration and pH as inputs, the error variance was found, and the result was 11. The error variance was obtained for the data set using the carbon dioxide concentration, pH, and dissolved oxygen concentration as inputs, and the result was 22.
[ test conditions A2]
Test conditions A2 were common test conditions of examples A-4 and A-5 and comparative example A-3. In test condition A1, the biological treatment tank was filled with the sponge-like carrier in a fluffy volume of 30% with respect to the volume of the biological treatment tank, the retention time in the biological treatment tank was 8 hours, and the water temperature was varied from 20 to 30 ℃. The BOD volume loading at the time of biological treatment is about 3kg/m 3 The pH of the water in the biological treatment water tank is 5.6-7.8 per day. The concentration of carbon dioxide emitted from the water in the biological treatment tank, the pH of the water in the biological treatment tank, and the water temperature are monitored.
Comparative example A-3
The BOD concentration is calculated according to the carbon dioxide concentration, and the determination coefficient R is calculated by unitary regression analysis according to the carbon dioxide concentration and each BOD concentration 2 The result was 0.770.
[ example A-4]
The BOD is calculated based on the carbon dioxide concentration and the water temperature in the biological treatment tank, and the determination coefficient R is calculated by neural network analysis for the carbon dioxide concentration, the water temperature and each BOD concentration 2 The result was 0.927. It is found that the carbon dioxide concentration and the water temperature are used as compared with the case where only the carbon dioxide concentration is usedThe calculation accuracy of the BOD concentration is greatly improved.
[ examples A to 5]
The BOD is calculated based on the carbon dioxide concentration, the water temperature and the pH in the biological treatment tank, and the determination coefficient R is calculated by analyzing the carbon dioxide concentration, the water temperature, the pH and the respective BOD concentrations through a neural network 2 The result was 0.926. It is found that the accuracy of calculation of the BOD concentration is significantly improved by using the carbon dioxide concentration, the water temperature, and the pH, as compared with the case of using only the carbon dioxide concentration.
As is clear from comparative example a and example a described above, the BOD concentration of the water to be treated can be calculated using a model created in advance using 1 or more measured values regarding the water quality of the water in the biological treatment tank in addition to the carbon dioxide concentration, and thereby the amount of the nutrient to be added can be optimized.
Example B and comparative example B
Example B and comparative example B will be described. Example B and comparative example B are examples and comparative examples corresponding to the second embodiment. The examples and comparative examples are distinguished by assigning branch numbers. First, the test conditions common to example B and comparative example B will be described.
Biological treatment by aerobic treatment of water to be treated as organic wastewater was carried out using a primary biological treatment tank having a volume of 19L as shown in fig. 5. Aerobic microorganisms are supported on a sponge-like carrier made of a hydrophobic polyurethane resin, and the sponge-like carrier is filled into a biological treatment tank in a volume of 20% by volume of the biological treatment tank. The retention time in the biological treatment tank was set to 18 hours. As the water to be treated, drainage containing isopropyl alcohol was used. The BOD concentration of the water to be treated is about 900mg/L (reference concentration), the nitrogen (N) concentration of the water to be treated is 2mg/L or less, and the phosphorus (P) concentration of the water to be treated is 0.1mg or less. The BOD volume loading at biological treatment is about 1kg/m 3 The water temperature is about 20 ℃, the dissolved oxygen concentration of the water in the biological treatment water tank is more than 2mg/L, and the pH value of the water in the biological treatment water tank is 6.0-7.5. For air dissipation, the flow rate of the biological treatment water tank is 3-5L/minAir is supplied.
To the water to be treated, nutrient salts (nitrogen (N) and phosphorus (P)) are sufficiently added so that BOD: n: p is 100:5:1 and monitoring the concentration of carbon dioxide emitted from the water in the biological treatment tank and the pH of the water in the biological treatment tank. The BOD concentration in the treated water was intentionally varied from 100% of the reference concentration to 30% and 60%, and this monitoring was repeatedly performed. The ability to accurately calculate the BOD concentration of the water being treated means that the accuracy of nutrient addition control is high.
Comparative example B-1
The BOD concentration of the water to be treated is calculated based on the carbon dioxide concentration, and the determination coefficient R is calculated by a unitary regression analysis for the carbon dioxide concentration and each BOD concentration 2 The result was 0.39.
Example B-1
The BOD concentration of the treated water is calculated according to the carbon dioxide concentration and the air volume, and the determination coefficient R is calculated by multiple regression analysis according to the carbon dioxide concentration, the air volume and each BOD concentration 2 The result was 0.82. It is found that the calculation accuracy of the BOD concentration is significantly improved by using the carbon dioxide concentration and the air volume, as compared with the case of using only the carbon dioxide concentration.
[ example B-2]
The BOD concentration of the water to be treated is calculated from the carbon dioxide concentration and the air volume, the product of the measured value of the carbon dioxide concentration and the measured value of the air volume is obtained, and the determination coefficient R is calculated by a simple regression analysis for each of the product and the BOD concentration 2 The result was 0.83. It is found that the calculation accuracy of the BOD concentration is further improved by using the product of the carbon dioxide concentration and the air volume.
Comparative example B-2
The BOD concentration of the water to be treated is calculated based on the carbon dioxide concentration and the pH, and the determination coefficient R is calculated by the multi-regression score for the carbon dioxide concentration, the pH and each BOD concentration 2 The result was 0.40.
[ example B-3]
The BOD concentration of the water to be treated is calculated from the carbon dioxide concentration, the air volume and the pH, and the BOD concentration, the air volume and the pH are adjusted to the carbon dioxide concentration, the air volume and the pHH and respective BOD concentrations, and calculating a determination coefficient R by multiple regression analysis 2 The result was 0.89. As compared with the case of using the carbon dioxide concentration and pH, it is found that the accuracy of calculating the BOD concentration is greatly improved by using the air volume in addition to the carbon dioxide concentration and pH.
[ example B-4]
The BOD concentration of the water to be treated is calculated from the carbon dioxide concentration, the air volume and the pH, the product of the measured value of the carbon dioxide concentration and the measured value of the air volume is obtained, and the determination coefficient R is calculated by multiple regression analysis for the product, the pH and each BOD concentration 2 The result was 0.96. As compared with the case of using the carbon dioxide concentration and the pH, it is found that the calculation accuracy of the BOD concentration is significantly improved by using the product of the measured value of the carbon dioxide concentration and the measured value of the air volume and the pH.
As is clear from comparative example B and example B described above, the BOD concentration of the water to be treated can be calculated using a model created in advance using at least the air volume in addition to the carbon dioxide concentration, thereby optimizing the amount of the nutrient to be added.
Example C and comparative example C
Example C and comparative example C will be described. Example C and comparative example C are examples and comparative examples corresponding to the third embodiment. The examples and comparative examples are distinguished by assigning branch numbers. First, the test conditions common to example C and comparative example C will be described.
Biological treatment by aerobic treatment of water to be treated as organic wastewater was carried out using a primary biological treatment tank having a volume of 19L. Aerobic microorganisms were supported on a sponge-like carrier made of a hydrophobic urethane resin, and the biological treatment tank was filled with the sponge-like carrier in a bulky volume of 30% with respect to the volume of the biological treatment tank. The retention time in the biological treatment tank was set to 8 hours. Isopropyl alcohol-containing wastewater was used as the water to be treated. The concentration of nitrogen (N) in the water to be treated is 2mg/L or less, and the concentration of phosphorus (P) in the water to be treated is 0.1mg or less. The pH of the water in the biological treatment water tank is 5.6-7.8. The air flow rate during ventilation was set to 10L/min, but actually varied between 9.7 and 10.3L/min.
Nutrient salts (nitrogen (N) and phosphorus (P)) are sufficiently added to the water to be treated, and the concentration of carbon dioxide discharged from the water in the biological treatment tank, the pH, water temperature and ORP of the water in the biological treatment tank are monitored.
Comparative example C-1
A monobasic regression analysis was performed using the respective measured values of the carbon dioxide concentration and the TOC concentration, and a relational expression for obtaining the TOC concentration from the carbon dioxide concentration was derived. Then, the TOC concentration is estimated from the carbon dioxide concentration using the relational expression, and a determination coefficient R with respect to the actually measured TOC concentration is calculated 2 The result was 0.770.
[ example C-1]
A multivariate regression analysis is performed using the respective measured values of the carbon dioxide concentration, the water temperature, and the TOC concentration, and a relational expression for obtaining the TOC concentration from the carbon dioxide concentration and the water temperature is derived. Then, the TOC concentration is estimated from the carbon dioxide concentration and the water temperature using the relational expression, and a determination coefficient R with respect to the actually measured TOC concentration is calculated 2 The result was 0.801.
[ example C-2]
A multiple regression analysis was performed using the respective measured values of the carbon dioxide concentration, ORP, and TOC concentration, and a relational expression for obtaining the TOC concentration from the carbon dioxide concentration and ORP was derived. Then, the TOC concentration is estimated from the carbon dioxide concentration and the ORP using the relational expression, and a determination coefficient R with respect to the actually measured TOC concentration is calculated 2 The result was 0.836.
[ example C-3]
Multivariate regression analysis was performed using the respective measured values of the carbon dioxide concentration, pH, and TOC concentration, and a relational expression for determining the TOC concentration from the carbon dioxide concentration and pH was derived. Then, the TOC concentration is estimated from the carbon dioxide concentration and the pH using the relational expression, and a determination coefficient R with respect to the actually measured TOC concentration is calculated 2 The result was 0.858.
[ example C-4]
Using carbon dioxide concentration, waterThe respective measured values of the temperature, pH and TOC concentration were subjected to multiple regression analysis, and a relational expression for determining the TOC concentration from the carbon dioxide concentration, the water temperature and the pH was derived. Then, the TOC concentration is estimated from the carbon dioxide concentration, the water temperature and the pH using the relational expression, and a determination coefficient R with respect to the actually measured TOC concentration is calculated 2 The result was 0.859.
[ example C-5]
A model based on a neural network is constructed by performing supervised learning with measured values of carbon dioxide concentration and water temperature as inputs and measured values of TOC concentration as outputs. Using the learned model, the TOC concentration is estimated from the carbon dioxide concentration and the water temperature, and a determination coefficient R of the actual TOC concentration is calculated 2 The result was 0.927.
[ example C-6]
A model based on a neural network is constructed by performing supervised learning with each measured value of the carbon dioxide concentration and ORP as an input and a measured value of the TOC concentration as an output. Using the learned model, the TOC concentration is estimated from the carbon dioxide concentration and ORP, and a determination coefficient R between the TOC concentration estimated using the model and the actual TOC concentration is calculated 2 The result was 0.933.
[ example C-7]
A model based on a neural network is constructed by performing supervised learning with the measured values of carbon dioxide concentration and pH as inputs and the measured value of TOC concentration as an output. Using the learned model, the TOC concentration is estimated from the carbon dioxide concentration and the pH, and a determination coefficient R of the actual TOC concentration is calculated 2 The result was 0.927.
[ example C-8]
A model based on a neural network is constructed by performing supervised learning with the measured values of carbon dioxide concentration, water temperature, and pH as inputs and the measured value of TOC concentration as an output. Using the learned model, the TOC concentration is estimated from the carbon dioxide concentration, the water temperature and the pH, and a determination coefficient R of the actual TOC concentration is calculated 2 The result was 0.926.
[ example C-9]
Carrying out carbon dioxide concentration, ORP, water temperature and pSupervised learning with the measured values of H as inputs and the measured value of TOC concentration as output constitutes a model based on a neural network. Using the learned model, the TOC concentration is estimated from the carbon dioxide concentration, ORP and water temperature, and a determination coefficient R of the actual TOC concentration is calculated 2 The result was 0.949.
[ example C-10]
The carbon dioxide concentration and the ventilation flow rate are multiplied by each other to obtain a carbon dioxide flow rate. A model based on a neural network is constructed by performing supervised learning with the measured values of the carbon dioxide flow rate, ORP, water temperature, and pH as inputs and the measured value of the TOC concentration as an output. Using the learned model, the TOC concentration is estimated from the carbon dioxide flow rate, ORP and water temperature, and a determination coefficient R of the TOC concentration from the actual measured concentration is calculated 2 The result was 0.971.
(description of reference numerals)
10. Biological treatment water tank
11. Carrier
12. Air diffusing device
13. Inlet pipe
14. Gas piping
15. Blower fan
16. Cover
21. Nutrient storage tank
22. Nutrient solution piping
23. Pump
31. 35 carbon dioxide concentration sensor
32. Air gauge
33. Water quality measuring part
34. Treated water quality measuring part
36. Gas measuring part
40. Control device
50. An arithmetic unit.
Claims (24)
1. A method for calculating an operation index used when organic wastewater is biologically treated in a biological treatment tank,
calculating the operation index from a measurement value of the treatment amount of the gas and a measurement value of the water quality of the water in the biological treatment tank based on a relationship obtained in advance for the treatment amount of the gas discharged from the water in the biological treatment tank, the water quality of the water in the biological treatment tank, and the water quality of the water to be treated flowing into the biological treatment tank,
the processing amount of the gas is at least one of a concentration, a flow rate, a volume, a pressure, and a substance amount of the gas,
the water quality of the water within the biologically treated water tank includes at least one of water temperature, pH, and oxidation-reduction potential,
the operation index is at least one of an organic matter concentration, a nitrogen concentration, a phosphorus concentration, a dissolved oxygen concentration, and an oxidation-reduction potential in the water to be treated.
2. The operation index calculation method according to claim 1,
the relationship is expressed by a neural network model obtained by learning a data set having a measured value of the amount of gas treated and a measured value of the water quality of the water in the biological treatment tank as input values and the operation index as an output value.
3. The operation index calculation method according to claim 1 or 2,
the gas is carbon dioxide.
4. A method for treating organic waste water by biological treatment,
calculating the operation index by the calculation method according to any one of claims 1 to 3,
and performing control in accordance with the calculated operation index to perform biological treatment of the water to be treated in the biological treatment tank.
5. A method for biologically treating organic wastewater in a biological treatment tank, comprising:
a first measurement step of measuring a carbon dioxide concentration in a gas discharged from water in the biological treatment water tank;
a second measurement step of obtaining 1 or more measurement values related to the water quality of the water in the biological treatment tank; and
and a control step of controlling the amount of the nutrient to be added to the organic wastewater based on the measured value of the carbon dioxide concentration obtained in the first measurement step and the 1 or more measured values obtained in the second measurement step.
6. The method for treating waste water according to claim 5,
the wastewater treatment method comprises the following steps: a calculation step of calculating the organic matter concentration of the organic wastewater from the measured value of the carbon dioxide concentration obtained in the first measurement step and the 1 or more measured values obtained in the second measurement step,
the control step is a step of controlling the amount of the nutrient added to the organic wastewater based on the organic matter concentration.
7. The method for treating waste water according to claim 5 or 6,
the measurement value obtained by the second measurement process includes a measurement value of at least one of pH and water temperature.
8. The method for treating waste water according to claim 5 or 6,
in the case where a plurality of biological treatment tanks are provided in series, the first measurement step and the second measurement step are performed on the first-stage biological treatment tank, and the control step controls the amount of nutrient added to the organic wastewater supplied to the first-stage biological treatment tank or the organic wastewater in the first-stage biological treatment tank.
9. A method for biologically treating organic wastewater in a biological treatment tank, comprising:
a first measurement step of measuring a concentration of a specific gas in a gas discharged from water in the biological treatment tank;
a second measurement step of measuring a flow rate of the gas supplied to the biological treatment tank or a flow rate of the gas discharged from the biological treatment tank; and
and a control step of controlling the amount of the nutrient to be added to the organic wastewater based on the measured concentration value obtained in the first measurement step and the measured flow rate value obtained in the second measurement step.
10. The method for treating waste water according to claim 9,
in the control step, the amount of the nutrient to be added to the organic wastewater is controlled based on the measured value of the concentration and the measured value of the flow rate, or based on the organic matter concentration of the organic wastewater calculated from a value obtained by multiplying the measured value of the concentration and the measured value of the flow rate.
11. The method for treating wastewater according to claim 9 or 10,
the wastewater treatment method comprises the following steps: a third measurement step of measuring the pH of the water in the biological treatment tank,
the specific gas is carbon dioxide and the specific gas is carbon dioxide,
in the control step, the amount of the nutrient to be added to the organic wastewater is controlled based on the measured concentration value, the measured flow rate value, and the measured pH value obtained in the third measurement step.
12. The method for treating wastewater according to claim 9 or 10,
in the case where a plurality of biological treatment tanks are provided in series, the first measurement step and the second measurement step are performed on the first-stage biological treatment tank, and the control step controls the amount of the organic wastewater supplied to the first-stage biological treatment tank or the amount of the nutrient added to the organic wastewater in the first-stage biological treatment tank.
13. A calculation device for calculating an operation index used when organic wastewater is biologically treated in a biological treatment tank, the calculation device comprising:
a gas measuring unit that measures a treatment amount of gas discharged from water in the biological treatment tank;
a water quality measuring unit that measures the water quality of the water in the biological treatment tank; and
a computing unit that calculates the operation index from a measurement value in the gas measuring unit and a measurement value in the water quality measuring unit based on a relationship that is obtained in advance for a treatment amount of gas discharged from water in the biological treatment tank, a water quality of the water in the biological treatment tank, and a water quality of water to be treated that flows into the biological treatment tank,
the processing amount of the gas is at least one of a concentration, a flow rate, a volume, a pressure, and a substance amount of the gas,
the water quality of the water within the biologically treated water tank includes at least one of water temperature, pH, and oxidation-reduction potential,
the operation index is at least one of an organic matter concentration, a nitrogen concentration, a phosphorus concentration, a dissolved oxygen concentration, and an oxidation-reduction potential in the water to be treated.
14. The computing device of claim 13,
the computing means further includes a treated water quality measuring unit for measuring the water quality of the treated water,
the calculation means learns a neural network using a data set having the measurement value of the gas measurement unit and the measurement value of the water quality measurement unit as input values and the measurement value of the treated water quality measurement unit as an output value, and expresses the relationship using a neural network model obtained by the learning.
15. The computing device of claim 13 or 14,
the gas is carbon dioxide.
16. A wastewater treatment device for biologically treating organic wastewater, comprising:
the computing device of any one of claims 13 to 15; and
an adding unit and/or an air diffusing unit, wherein the adding unit adds nutrient substances to the water to be treated, the air diffusing unit diffuses air into the biological treatment water tank,
at least one of the adding means and the air diffusing means is controlled according to the calculated operation index.
17. A drainage treatment device is provided with:
a biological treatment tank for biologically treating organic wastewater;
an addition unit that adds a nutrient to the organic drainage;
a first measurement unit having a first sensor that measures a carbon dioxide concentration in a gas discharged from water in the biological treatment water tank;
a second measurement unit that acquires 1 or more measurement values related to the water quality of the water in the biological treatment tank; and
a control unit that controls an amount of the nutrient to be added by the addition unit based on the carbon dioxide concentration value obtained by the first measurement unit and the 1 or more measurement values obtained by the second measurement unit.
18. The drain treatment apparatus according to claim 17,
the control means calculates the organic matter concentration of the organic wastewater from the measured value of the carbon dioxide concentration obtained by the first measuring means and the 1 or more measured values obtained by the second measuring means, and controls the amount of the nutrient to be added based on the organic matter concentration.
19. The drainage treatment device according to claim 17 or 18,
the measurement value acquired by the second measurement unit includes a measurement value of at least one of pH and water temperature.
20. The drain treatment apparatus according to claim 17 or 18,
a plurality of the biological treatment water tanks are arranged in series,
the addition unit adds a nutrient to the organic wastewater supplied to the first-stage biological treatment water tank or the organic wastewater in the first-stage biological treatment water tank,
the first measuring unit and the second measuring unit are provided for the first-stage biological treatment water tank.
21. A wastewater treatment apparatus includes:
a biological treatment tank for biologically treating organic wastewater;
an addition unit that adds a nutrient to the organic drainage;
a first measuring unit that measures a concentration of a specific gas in a gas discharged from water in the biological treatment water tank;
a second measurement unit that measures a flow rate of the gas supplied to the biological treatment tank or a flow rate of the gas discharged from the biological treatment tank; and
a control unit that controls an addition amount of the nutrient to be added by the addition unit based on the measurement value of the concentration obtained by the first measurement unit and the measurement value of the flow rate obtained by the second measurement unit.
22. The drain treatment apparatus according to claim 21,
the control unit controls the addition amount of the nutrient based on the measured value of the concentration and the measured value of the flow rate, or based on the organic matter concentration of the organic wastewater calculated from a value obtained by multiplying the measured value of the concentration and the measured value of the flow rate.
23. The drainage treatment device according to claim 21 or 22,
the wastewater treatment apparatus includes a third measurement unit that measures the pH of the water in the biological treatment tank,
the specific gas is carbon dioxide and the specific gas is,
the control unit controls an addition amount of the nutrient to be added to the organic drainage based on the measurement value of the concentration, the measurement value of the flow rate, and the measurement value of the pH obtained by the third measurement unit.
24. The drain treatment apparatus according to claim 21 or 22,
a plurality of the biological treatment water tanks are arranged in series,
the addition unit adds a nutrient to the organic wastewater supplied to the first-stage biological treatment water tank or the organic wastewater in the first-stage biological treatment water tank,
the first and second measuring units are provided for the first-stage biological treatment tank.
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| JP2021081412A JP2022175195A (en) | 2021-05-13 | 2021-05-13 | Calculation method and calculation device of operation indicator, biological treatment method, and biological treatment apparatus |
| JP2021081413A JP2022175196A (en) | 2021-05-13 | 2021-05-13 | Wastewater treatment method and wastewater treatment device |
| JP2021-081412 | 2021-05-13 | ||
| JP2021-081413 | 2021-05-13 | ||
| JP2021098016A JP2022189442A (en) | 2021-06-11 | 2021-06-11 | Waste water treatment method and waste water treatment apparatus |
| JP2021-098016 | 2021-06-11 |
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