Detection method, detection device and program

Abstract

To detect a decrease in activity of bacteria in an aeration tank in advance, when biological treatment is applied to ammonia-free water in the aeration tank to obtain treated water.SOLUTION: When biological treatment is applied to ammonia-free water charged to an aeration tank 4 to obtain treated water, a decrease in activity of bacteria in the aeration tank 4 is detected in advance based on a value of a first principal component obtained by principal component analysis for management items of the aeration tank 4. It is preferable to determine that a decrease in activity can occur when the value of the first principal component shows an increasing trend continuously for a certain period of time.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a detection method, a detection device, and a program. [Background technology]

[0002] Ammonia water (ammonia water) is obtained by spraying water onto gas (coke oven gas) discharged from a coke oven installed in a steelworks, etc. Conventionally, as shown in Patent Document 1, ammonia water is treated to prepare it for discharge (ammonia water treatment).

[0003] In ammonia water treatment, the ammonia contained in the ammonia water is first distilled and separated in an ammonia stripper to obtain ammonia-free water (ammonia-free water). The ammonia-free water is then subjected to biological treatment in an aeration tank containing aerobic bacteria (activated sludge). This produces treated water from which the COD components (organic matter) that could not be completely removed by the ammonia stripper have been removed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-192679 Summary of the Invention [Problem to be solved by the invention]

[0005] If bacterial activity in the aeration tank decreases (sludge modulation), the deammonium sewage cannot be sufficiently biologically treated. Once sludge abnormality occurs, it becomes necessary to reduce production in the coke oven, which is the source of ammonia water (deammonia water), until the bacteria in the aeration tank recovers, which can have a major impact on the entire steelworks in which the coke ovens are installed. However, it is difficult to detect the occurrence of sludge abnormalities in advance.

[0006] Therefore, an object of the present invention is to detect in advance a decrease in bacterial activity in an aeration tank when treated water is obtained by subjecting deammonia-removed water to biological treatment in the aeration tank. [Means for solving the problem]

[0007] As a result of extensive investigations, the present inventors have found that the above object can be achieved by employing the following configuration, and have completed the present invention. That is, the present invention provides the following [1] to

[10] . [1] A detection method for detecting in advance a decrease in bacterial activity in an aeration tank based on the value of the first principal component obtained by principal component analysis targeting the control items of the aeration tank when treated water is obtained by subjecting deammonium sulphate water fed into the aeration tank to biological treatment. [2] The detection method according to [1] above, wherein it is determined that the decrease in activity may occur when the value of the first principal component shows an increasing trend for a certain period of time. [3] The detection method according to [2] above, wherein the certain period is a period calculated from the volume of the aeration tank and the amount of water flowing into the aeration tank. [4] The detection method according to any one of [1] to [3] above, wherein the control items of the aeration tank include the amount of the deammonium sulphate water fed into the aeration tank, the amount of dissolved oxygen in the aeration tank, the pH of the aeration tank, the temperature of the aeration tank, the oxidation-reduction potential of the aeration tank, and the SCN concentration of the treated water. [5] A detection device comprising: a detection unit that detects in advance a decrease in bacterial activity in the aeration tank based on the value of a first principal component obtained by principal component analysis targeting a management item of the aeration tank, when treated water is obtained by subjecting deammonia-depleted water to be charged into an aeration tank to biological treatment; and an alarm unit that alarms the detection result by the detection unit. [6] The detection device according to [5] above, wherein the detection unit determines that the activity decrease may occur when the value of the first principal component shows an increasing trend for a certain period of time. [7] The detection device according to [6] above, further comprising a period calculation unit, which calculates the certain period from the volume of the aeration tank and the amount of water flowing into the aeration tank. [8] The detection device according to any of [5] to [7] above, further comprising a principal component analysis unit, which performs principal component analysis on the amount of the deammonium sulphate water fed into the aeration tank, the amount of dissolved oxygen in the aeration tank, the pH of the aeration tank, the temperature of the aeration tank, the oxidation-reduction potential of the aeration tank, and the SCN concentration of the treated water to obtain the first principal component. [9] A program for causing a computer to execute each step of the detection method according to any one of [1] to [3] above.

[10] A program for causing a computer to execute each step of the detection method described in [4] above. Effect of the Invention

[0008] According to the present invention, when treated water is obtained by subjecting deammonium sulphate water to biological treatment in an aeration tank, a decrease in bacterial activity in the aeration tank can be detected in advance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram showing a configuration of a detection device. [Diagram 2] FIG. 1 is a schematic diagram showing equipment used for ammonia water treatment. [Diagram 3] This is a graph showing the values ​​of each control item in the aeration tank over time when sludge abnormality actually occurred. (a) shows the amount of deammonium ammonium water fed to the aeration tank (amount of deammonium ammonium water fed), (b) shows the amount of dissolved oxygen in the aeration tank, (c) shows the pH of the aeration tank, (d) shows the temperature of the aeration tank, (e) shows the oxidation-reduction potential of the aeration tank, and the SCN concentration of the treated water. [Figure 4] Graph (a) is a graph showing the value of the first principal component expressed by equation (2) over time, and graph (b) is a graph showing the value of the SCN concentration in the treated water over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First, the detection device 11 of this embodiment will be described. FIG. 1 is a block diagram showing the configuration of the detection device 11. As shown in FIG. The detection device 11 is, for example, a computer such as a personal computer (PC), and includes a notification unit 12, a management item acquisition unit 13, a graph creation unit 14, a principal component analysis unit 15, a detection unit 16, and a period calculation unit 17. The notification unit 12 is, for example, a monitor for a PC, and has a display screen. The management item acquisition unit 13, graph creation unit 14, principal component analysis unit 15, detection unit 16 and period calculation unit 17 are composed of, for example, a CPU (central processing unit), a main memory device such as a DRAM (dynamic random access memory) connected to the CPU, a large-capacity memory device such as an SSD (solid state drive) or HDD (hard disk drive) connected to the CPU, and a program that operates the CPU. The processes executed by each of these units will be described later.

[0011] Next, the flow of the ammonia water (ammonia water) treatment will be described with reference to FIG. 2 is a schematic diagram showing a facility used for treating ammonia water. First, coke oven gas (C gas) is discharged from a coke oven 1 installed inside a steelworks or the like.

[0012] Ammonia water (ammonia water) is obtained by spraying water onto C gas (crude C gas) discharged from the coke oven 1. More specifically, a mixture of ammonia water and tar is obtained. The mixture of ammonia water and tar is then passed through a tar decanter 2 to remove the tar, thereby obtaining ammonia water (raw ammonia water). Thereafter, the ammonia contained in the raw ammonia water is separated by distillation in the ammonia stripper 3. As a result, ammonia-free water (ammonia-free water) is obtained.

[0013] The crude C gas discharged from the coke oven 1 and from which tar and the like have been removed is returned to the ammonia separated from the ammonia solution, and is then introduced into a C gas refining facility 8. The C gas is refined in the C gas refining facility 8 to obtain a refined C gas.

[0014] The deammonia water contains COD (Chemical Oxygen Demand) components that cannot be completely removed by the ammonia stripper 3. Examples of the COD components include organic substances such as phenol (C6H5OH) and thiocyanate (SCN). The deammonium sulphate water containing COD components is fed into the aeration tank 4. In addition to the deammonium sulphate water, dilution water is also fed into the aeration tank 4. In the aeration tank 4, the deammonium sulphate water is subjected to biological treatment using aerobic bacteria (activated sludge). As a result, treated water from which the COD components have been removed is obtained.

[0015] The resulting treated water is transferred to a settling tank 5, where the sludge contained in the treated water is settled and removed. In order to keep the amount of sludge in the aeration tank 4 constant, the sludge is returned from the settling tank 5 to the aeration tank 4.

[0016] Thereafter, the treated water from which the sludge has been removed is transferred to the coagulation and sedimentation tank 6. In the coagulation and sedimentation tank 6, a chemical (coagulant) is added to the treated water, and the pH of the treated water is also adjusted. This allows heavy metal ions and other substances in the treated water to be precipitated and removed. The treated water that has passed through the coagulation and sedimentation tank 6 is finally introduced into secondary treatment equipment 7, where it is subjected to secondary treatment such as filtration using sand or activated carbon, and then discharged as effluent.

[0017] However, if the activity of bacteria in the aeration tank 4 decreases (sludge modulation), the deammonia-free water fed to the aeration tank 4 cannot be sufficiently biologically treated, resulting in insufficient removal of COD components. Once this sludge abnormality occurs, it becomes necessary to reduce production in the coke oven 1, which is the source of the ammonia water, until the bacteria in the aeration tank 4 are restored, which may have a significant impact on the entire steelworks. For this reason, the aeration tank 4 is particularly important for the operation of ammonia water treatment plants.

[0018] Specific examples of control items (operation indexes) for the aeration tank 4 include the amount of deammonium ammonium water charged to the aeration tank 4 (amount of deammonium ammonium water charged); the amount of dissolved oxygen in the aeration tank 4; the pH of the aeration tank 4; the temperature of the aeration tank 4; the oxidation-reduction potential of the aeration tank 4; the SCN concentration of the treated water obtained by biological treatment in the aeration tank 4 (SCN concentration of treated water); the SCN concentration of the deammonium ammonium water charged to the aeration tank 4; the COD component concentration of the deammonium ammonium water charged to the aeration tank 4; the sludge concentration in the aeration tank 4; and the like.

[0019] The control item acquisition unit 13 of the detection device 11 continuously acquires the values ​​(data) of these control items during the operation of ammonia water treatment. Then, the graph creation unit 14 of the detection device 11 creates a graph (see, for example, Figures 3(a) to 3(f)) based on the values ​​of the management items acquired by the management item acquisition unit 13, and displays the created graph on the display screen of the notification unit 12.

[0020] Figures 3(a) to 3(f) are graphs showing the values ​​of each control item (amount of deammoniated water fed, amount of dissolved oxygen, pH, temperature, oxidation-reduction potential, and SCN concentration in the treated water) in the aeration tank 4 over time when sludge modulation actually occurred. More specifically, Figures 3(a) to 3(f) show the values ​​(average values ​​every two hours) of each management item of the aeration tank 4 acquired by the management item acquisition unit 13 from April 1st to September 1st of a certain year, which are then plotted on a graph by the graph creation unit 14.

[0021] Sludge deterioration is caused by a decrease in the activity of decomposing bacteria that break down each organic matter. In particular, the SCN-decomposing bacteria that break down SCN are the most vulnerable to shocks caused by fluctuations in operation. Therefore, when sludge abnormality occurs, first the SCN concentration in the treated water obtained by biological treatment in the aeration tank 4 (treated water SCN concentration) increases, then other decomposing bacteria become abnormal, and further the concentration of COD components in the treated water increases.

[0022] Therefore, in order to prevent the occurrence of sludge abnormality, it is conceivable to monitor the SCN concentration in the treated water and operate so that it does not exceed a certain value. However, as shown in the graph in Figure 3(f), when sludge modulation occurs, the SCN concentration in the treated water rises extremely rapidly, making it difficult to detect signs of sludge modulation by monitoring the SCN concentration in the treated water.

[0023] By the way, looking at the remaining graphs in Fig. 3(a) to Fig. 3(e), changes can be seen in the amount of dissolved oxygen, pH, temperature, etc. in the aeration tank 4 in the period before sludge modulation occurs. From the above, it is considered that the decrease in bacterial activity (sludge modulation) in the aeration tank 4 is caused by a combination of multiple control items of the aeration tank 4.

[0024] Therefore, in this embodiment, we use principal component analysis, which can create composite variables (principal components) by weighting multivariate data. Principal component analysis can reduce multiple variables to one variable while maintaining the amount of information in the original data as much as possible. The principal components created by principal component analysis are expressed by the following formula (1), where α, β, γ, etc. are principal component coefficients (contributions) and A, B, C, etc. are variables (data). Principal component=αA+βB+γC…+constant term (1) Among the principal components, the first principal component is the one that summarizes the original data so that the variance (dispersion) is the greatest, and it contains the most information of the original data.

[0025] Specifically, the principal component analysis unit 15 of the detection device 11 performs principal component analysis on the control items of the aeration tank 4 (the control items acquired by the control item acquisition unit 13) to obtain a first principal component. For example, when a principal component analysis is performed based on the values ​​of each control item shown in the graphs of FIGS. 3(a) to 3(f), a first principal component represented by the following formula (2) is obtained.

[0026] First principal component = 1.766 x (pH [-]) + 0.133 x (temperature [℃]) + 0.09 x (SCN concentration in treated water [mg / L]) + 0.03 x (oxidation-reduction potential [mV]) - 0.212 x (amount of dissolved oxygen [mg / L]) - 0.015 x (amount of deammonia-removed water charged [m 3 / h])-14.982 (2)

[0027] FIG. 4(a) is a graph showing the value of the first principal component expressed by the above formula (2) over time. FIG. 4(b) is a graph showing the SCN concentration in the treated water over time, and is a graph of FIG. 3(f) at a different scale. The graphs in FIG. 4( a ) and FIG. 4( b ) are created by the graph creation unit 14 of the detection device 11 and displayed on the display screen of the notification unit 12 .

[0028] To reiterate, as shown in the graph in Figure 4(b), when sludge modulation occurs, the SCN concentration in the treated water rises sharply, so it is difficult to detect signs of sludge modulation by monitoring the SCN concentration in the treated water. On the other hand, as shown in the graph in Figure 4(a), it can be clearly seen that the first principal component gradually increases from a certain point before the occurrence of sludge modulation (a sudden increase in the SCN concentration in the treated water).

[0029] Therefore, during the operation of the ammonia water treatment, the detection unit 16 of the detection device 11 continues to monitor the value of the first principal component. Then, when an increase (an increasing tendency) in the first principal component is continuously observed for a certain period of time, the detection unit 16 judges that sludge degeneration may occur in the aeration tank 4 thereafter, and causes the notification unit 12 to display a message to that effect on the display screen. This allows the operator to detect the occurrence of sludge abnormalities in advance.

[0030] The "certain period" is calculated by the period calculation unit 17 of the detection device 11 from data on the volume of the aeration tank 4 and the amount of water (inflow water amount) flowing into the aeration tank 4, for example. The influent is a general term for the dehydrated water fed into the aeration tank 4, the dilution water fed into the aeration tank 4, and the sludge returned from the settling tank 5 to the aeration tank 4 (returned sludge), and the amount of influent is the total amount of these. For example, the volume of aeration tank 4 is 3780 m 3 The inflow volume is about 80m 3 / h. Generally, to replace the liquid in a tank, an inflow of water three times the volume of the tank is required. Therefore, when calculating the time t for replacing the liquid in the aeration tank 4, we calculate (3780÷80)×3=142 hours ≒ approximately 6 days. If the value of the first principal component continues to rise beyond time t (if the "certain period" during which the first principal component shows an upward trend exceeds time t), it can be determined that the influence of reduced bacterial activity is greater than the influence of disturbance factors (changes in the properties of the inflowing water).

[0031] Since each coefficient in the first principal component represents the contribution of each control item, by looking at these, it is possible to determine which control item should be adjusted as a priority when the value of the first principal component increases. For example, the first principal component (for convenience, referred to as the "first principal component a") represented by the above formula (2) (shown in the graph of Figure 4(a)) is an example of a case where sludge abnormality occurs due to the control items of the aeration tank 4, mainly the pH, temperature, and amount of dissolved oxygen, falling outside the appropriate values. For this reason, in the first principal component a represented by the above formula (2), the coefficient of pH is the largest, followed by the coefficients of temperature and the amount of dissolved oxygen. Therefore, when the value of the first principal component a increases, it is understood that the pH, temperature and amount of dissolved oxygen in the aeration tank 4 should be preferentially adjusted to appropriate values ​​(for example, the pH in the aeration tank 4 should be lowered) in order to prevent the occurrence of sludge modulation.

[0032] The first principal component is not limited to the above. For example, when sludge modulation occurs due to the oxidation-reduction potential being outside the appropriate value, if principal component analysis is performed, a first principal component (for convenience, referred to as “first principal component b”) different from the first principal component a is obtained.

[0033] Therefore, in each case in which sludge modulation occurs due to different factors, the principal component analysis unit 15 performs principal component analysis to preliminarily determine a plurality of different first principal components (first principal component a, first principal component b, first principal component c, first principal component d, ...). In addition, by the detection unit 16 monitoring the values ​​of these multiple first principal components during the operation of the ammonia water treatment, it is possible to more accurately detect in advance sludge abnormalities that may occur due to various factors.

[0034] At this time, the graph creation unit 14 creates graphs of a plurality of first principal components (first principal component a, first principal component b, ...) and displays them side by side on the display screen of the notification unit 12. Then, among the plurality of graphs displayed side by side, only the graph of the first principal component for which an increase has been recognized for a certain period of time is made noticeable by changing the color or making it glow. As a result, even if there are multiple graphs of the first principal component, the operator can quickly grasp, among the control items of the aeration tank 4, the control item that should be adjusted with priority. [Explanation of symbols]

[0035] 1: Coke oven 2: Tar decanter 3: Ammonia stripper 4: Aeration tank 5: Sedimentation tank 6: Coagulation and settling tank 7: Secondary treatment facility 8:C Gas purification facility 11:Detection device 12: Notification Department 13: Management item acquisition part 14: Graph creation section 15:Principal component analysis section 16: Detection unit 17: Period calculation section

Claims

1. A detection method for detecting a decrease in bacterial activity in an aeration tank in advance based on the value of a first principal component obtained by principal component analysis targeting a control item of the aeration tank, when treated water is obtained by subjecting deammonium sulphate water to be charged into the aeration tank to biological treatment.

2. The detection method according to claim 1 , further comprising determining that the decrease in activity may occur when the value of the first principal component shows an increasing trend for a certain period of time.

3. The detection method according to claim 2 , wherein the certain period of time is calculated from a volume of the aeration tank and an amount of water flowing into the aeration tank.

4. 4. The detection method according to claim 1, wherein the control items of the aeration tank include an amount of the deammonium water charged into the aeration tank, an amount of dissolved oxygen in the aeration tank, a pH of the aeration tank, a temperature of the aeration tank, an oxidation-reduction potential of the aeration tank, and an SCN concentration of the treated water.

5. a detection unit that detects in advance a decrease in bacterial activity in the aeration tank based on a value of a first principal component obtained by a principal component analysis targeting a control item of the aeration tank when a biological treatment is performed on the deammonia water charged into the aeration tank to obtain treated water; a notification unit that notifies a result of detection by the detection unit.

6. The detection device according to claim 5 , wherein the detection unit determines that the decrease in activity may occur when the value of the first principal component shows an increasing trend for a certain period of time.

7. Further, a period calculation unit is provided, The detection device according to claim 6 , wherein the period calculation unit calculates the certain period from a volume of the aeration tank and an amount of water flowing into the aeration tank.

8. Further, a principal component analysis unit is provided, The detection device according to any one of claims 5 to 7, wherein the principal component analysis unit obtains the first principal component by performing principal component analysis on the amount of the deammonium sulphate water charged into the aeration tank, the amount of dissolved oxygen in the aeration tank, the pH of the aeration tank, the temperature of the aeration tank, the oxidation-reduction potential of the aeration tank, and the SCN concentration of the treated water.

9. A program for causing a computer to execute each step of the detection method according to any one of claims 1 to 3.

10. A program for causing a computer to execute each step of the detection method according to claim 4.

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