Evaluation system, evaluation method, and evaluation program

Abstract

An evaluation system 1 is installed downstream of a filter M in a flow path P that includes the filter M, to evaluate the state of the filter M, the evaluation system 1 including a turbidity meter 2 for measuring the turbidity of a fluid flowing through the flow path P, a water intake pipe 3 for taking in at least a part of the fluid flowing through the flow path P, an inspection filter 4 for filtering the fluid taken in from the water intake pipe 3, a first pressure gauge 6 for measuring the pressure of the fluid upstream of the inspection filter 4, a second pressure gauge 7 for measuring the pressure of the fluid downstream of the inspection filter 4, a flowmeter 8 for measuring the flow rate of the fluid downstream of the inspection filter 4, and a computing device, wherein the computing device is capable of achieving a first evaluation function for evaluating the state of the filter M on the basis of the measured value from the turbidity meter 2, and a second evaluation function for evaluating the state of the filter M on the basis of the measured value from the first pressure gauge 6 and the measured value from the second pressure gauge 7.

Description

Evaluation system, evaluation method, and evaluation program

[0001] The present invention relates to an evaluation system, an evaluation method, and an evaluation program for evaluating the condition of a filter.

[0002] Various filters are used in fields such as wastewater treatment. These filters are installed to prevent particles such as pathogenic microorganisms from flowing out to the secondary side, so it is necessary to guarantee the integrity of the filters.

[0003] Japanese Patent Laid-Open Publication No. 2000-279769 (Patent Document 1) discloses a device that detects membrane damage using the detection value of a turbidity meter installed on the secondary side of a membrane filtration device. Japanese Patent Laid-Open Publication No. 2023-132840 (Patent Document 2) discloses a device that determines the state of a hydrogen-permeable membrane based on the pressure or flow rate on the primary and secondary sides of the hydrogen-permeable membrane.

[0004] JP 2000-279769 A JP 2023-132840 A

[0005] The technology of detecting membrane damage based on the turbidity on the secondary side, as in Patent Document 1, leaves room for improvement in accuracy. The method using a turbidimeter has difficulty distinguishing between the intrusion of air bubbles and the outflow of particles due to membrane damage, and there have been cases where the intrusion of air bubbles has been erroneously determined as membrane damage. Furthermore, there have been cases where particles have accumulated at the site of membrane damage, temporarily stopping the outflow of particles, and membrane damage has not manifested itself as an increase in turbidity.

[0006] The technology of detecting damage based on measured values ​​of pressure and the like, as in Patent Document 2, has room for improvement in responsiveness, because when a detectable difference in pressure and the like is observed between the primary and secondary sides of the membrane, damage is often already quite advanced.

[0007] Therefore, it is desirable to achieve both accuracy and responsiveness in evaluating the filter condition.

[0008] The evaluation system of the present invention is an evaluation system that is installed downstream of a filter in a flow path that has a filter and evaluates the state of the filter, and includes a turbidity meter that measures the turbidity of a fluid flowing through the flow path, an intake pipe that takes in at least a portion of the fluid flowing through the flow path, an inspection filter that filters the fluid taken in from the intake pipe, a first pressure gauge that measures the pressure of the fluid upstream of the inspection filter, a second pressure gauge that measures the pressure of the fluid downstream of the inspection filter, a flow meter that measures the flow rate of the fluid downstream of the inspection filter, and a computing device, and is characterized in that the computing device is capable of realizing a first evaluation function that evaluates the state of the filter based on the measurement value of the turbidity meter, and a second evaluation function that evaluates the state of the filter based on the measurement value of the first pressure gauge and the measurement value of the second pressure gauge.

[0009] The evaluation method of the present invention is an evaluation method that is carried out downstream of a filter in a flow path that has a filter, and evaluates the state of the filter, and is characterized by including: a turbidity measurement process that measures the turbidity of a fluid flowing through the flow path; a water intake process that takes in at least a portion of the fluid flowing through the flow path; a filtration process that filters the fluid taken in in the water intake process using an inspection filter; a first pressure measurement process that measures the pressure of the fluid upstream of the inspection filter; a second pressure measurement process that measures the pressure of the fluid downstream of the inspection filter; a flow rate measurement process that measures the flow rate of the fluid downstream of the inspection filter; a first evaluation process that evaluates the state of the filter based on the turbidity measurement value; and a second evaluation process that evaluates the state of the filter based on the pressure in the first pressure measurement process and the pressure in the second pressure measurement process.

[0010] The evaluation program of the present invention is an evaluation program for evaluating the state of a filter downstream of a filter in a flow path that has a filter, and when executed by a computer, is characterized by realizing a first evaluation function that evaluates the state of the filter based on the turbidity of the fluid flowing through the flow path, and a second evaluation function that evaluates the state of the filter based on measurement values ​​measured by filtering at least a portion of the fluid flowing through the flow path through an inspection filter, the measurement values ​​being the pressure of the fluid measured upstream of the inspection filter and the pressure of the fluid measured downstream of the inspection filter.

[0011] According to these configurations, the filter condition is evaluated using both an evaluation based on turbidity and an evaluation based on pressure and flow rate, so that both accuracy and responsiveness can be achieved.

[0012] Preferred embodiments of the present invention will be described below, but the scope of the present invention is not limited to the preferred embodiments described below.

[0013] In one aspect of the evaluation system according to the present invention, it is preferable that the second evaluation function is realized when the first evaluation function evaluates that the filter may be damaged.

[0014] According to this configuration, a rough evaluation is performed using the first evaluation function, which has excellent responsiveness, and then a detailed evaluation is performed using the second evaluation function, which has excellent accuracy, making it particularly easy to improve accuracy and responsiveness.

[0015] In one aspect of the evaluation system of the present invention, the calculation device can further realize a water resistance identification function for identifying the water resistance of the test filter, a change amount identification function for identifying the amount of change in the water resistance, and an acceleration index identification function for identifying an acceleration index which is the rate of change of the amount of change, and it is preferable that the second evaluation function evaluates the state of the filter based on the acceleration index at the time to be determined.

[0016] According to this configuration, the change in the state of the test filter caused by the damage of the filter can be grasped cumulatively, and therefore evaluation with high sensitivity is possible.

[0017] In one aspect of the evaluation system according to the present invention, the inspection filter is preferably a track-edged membrane filter.

[0018] According to this configuration, when the filter is damaged and large particles flow into the inspection filter, a pressure loss due to the inflow of the particles occurs abruptly, making it easy to detect the damage to the filter.

[0019] In one aspect, the evaluation system of the present invention comprises a branch pipe on the primary side of the inspection filter that guides the liquid portion of the fluid to the inspection filter and to a gas flow path that leads the gas portion of the fluid out of the system, and a liquid flow path connected to the secondary side of the inspection filter that guides the liquid portion of the fluid that has passed through the inspection filter out of the system, and it is preferable that the gas flow path is at least partially located at a lower position than the liquid flow path.

[0020] According to this configuration, the gas portion can be encouraged to escape, so that the measurement value of the first pressure gauge tends to be accurate.

[0021] In one aspect of the evaluation system according to the present invention, the inspection filter is preferably arranged so that the primary side of the inspection filter faces directly toward the flow direction of the fluid taken in from the water intake pipe.

[0022] According to this configuration, particles flowing into the inspection filter can be easily captured, enabling evaluation with high sensitivity.

[0023] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which is given with reference to the drawings.

[0024] Fig. 1 is a schematic diagram of an evaluation system according to an embodiment; Fig. 2 is a block diagram showing the configuration of an evaluation system according to an embodiment; Fig. 3 is a flow diagram showing the procedure of an evaluation method according to an embodiment; Fig. 4 is a diagram showing an example of change over time in water flow resistance; Fig. 5 is a diagram showing an example of change over time in the amount of change in water flow resistance; Fig. 6 is a diagram showing an example of change over time in the acceleration index of water flow resistance.

[0025] An evaluation system, an evaluation method, and an evaluation program according to the present invention will be described below with reference to the drawings. Hereinafter, an example will be described in which the evaluation system according to the present invention is applied to an evaluation system 1 that evaluates the state of a membrane separation device M (an example of a filter) that filters water that has been biologically treated in a membrane bioreactor (MBR).

[0026] [Configuration of Evaluation System] The evaluation system 1 according to this embodiment is installed downstream of the membrane separation device M in a flow path P including the membrane separation device M, and is a system for evaluating the state of the membrane separation device M. The evaluation system 1 includes a turbidity meter 2, a water intake pipe 3, an inspection filter 4, a guide path 5, a first pressure gauge 6, a second pressure gauge 7, a flow meter 8, and a computing device 9 ( FIG. 1 ).

[0027] The turbidity meter 2 is a device that measures the turbidity of the fluid flowing through the flow path P. The turbidity meter 2 can be any known device for measuring the turbidity of a liquid, and examples thereof include a device that measures the intensity of transmitted light that has passed through a sample, and a device that measures the intensity of scattered light that has been scattered by the sample. In this embodiment, an inlet pipe 21 that branches off from the flow path P is provided to guide a portion of the fluid to the turbidity meter 2. However, the turbidity meter 2 may also be provided in the flow path P.

[0028] The intake pipe 3 is a pipe for taking in at least a portion of the fluid flowing through the flow path P and guiding it to the inspection filter 4. A pump 31 is provided in the intake pipe 3. The pump 31 pressurizes the fluid taken in from the flow path P and supplies it to the inspection filter 4, and is operated when it is necessary to supply fluid to the inspection filter 4.

[0029] Valves B1 and B2 are provided on the inlet pipe 21 and the intake pipe 3, respectively. Both valves B1 and B2 are normally open. When it is desired to stop the flow of fluid to devices downstream of the inlet pipe 21 and the intake pipe 3 (such as the turbidity meter 2 and the inspection filter 4) for maintenance or other reasons, the corresponding valves B1 and B2 are closed.

[0030] The inspection filter 4 is a filter that filters the fluid taken in from the water intake pipe 3. The specifications of the inspection filter 4 (size of particles that can be captured, capture rate, material, etc.) are appropriately selected depending on the degree of damage to the membrane separation device M that is to be detected. As an example, if a filter that can capture particles with a sphere-equivalent diameter of about 1.2 μm is used, it is possible to detect damage to the membrane separation device M to the extent that E. coli is leaking to the secondary side of the membrane separation device M. The material of the inspection filter 4 can be, but is not limited to, polycarbonate, polyester, polyethylene terephthalate, etc.

[0031] The inspection filter 4 is preferably a track-edged membrane filter. Because track-edged membrane filters have a small pore size variance, the particle size to be captured can be clearly defined. That is, track-edged membrane filters smoothly pass small particles smaller than the particle size to be captured, but rapidly clog when large particles equal to or larger than the particle size to be captured flow in. Therefore, if the inspection filter 4 is a track-edged membrane filter, when the membrane separation device M is damaged and large particles flow into the inspection filter 4, a steep pressure drop occurs due to the inflow of the particles, making it easy to detect the inflow of particles (i.e., damage to the membrane separation device M).

[0032] The inspection filter 4 is installed so that its primary side is located at the top and its secondary side is located at the bottom. That is, the fluid taken in from the water intake pipe 3 (fluid pressurized by the pump 31) is supplied from above, and the filtered fluid flows out from below. The primary side of the inspection filter 4 faces the direction of fluid flow. That is, the inspection filter 4 is installed in a manner that allows so-called dead-end filtration.

[0033] The guide path 5 is a pipe for guiding a fluid on the primary side and secondary side of the inspection filter 4. The guide path 5 has a branch pipe 51, a gas flow path 52, and a liquid flow path 53. An on-off valve 54 is provided in the gas flow path 52.

[0034] The branch pipe 51 is a trifurcated pipe that guides the liquid and gas portions of the fluid into separate paths on the primary side of the inspection filter 4. The portion of the branch pipe 51 that extends laterally is connected to the secondary side of the pump 31, the portion that extends upward is connected to the gas flow path 52, and the portion that extends downward is connected to the primary side of the inspection filter 4. The liquid and gas portions of the fluid that flow into the branch pipe 51 are separated into gas and liquid by gravity, with the relatively light gas portion being guided upward and the relatively heavy liquid portion being guided downward.

[0035] The gas flow path 52 is a flow path that guides the gas portion of the fluid separated in the branch pipe 51 to the outside of the system. As described above, the gas flow path 52 is provided with an on-off valve 54. The on-off valve 54 is normally closed and is opened under predetermined conditions (for example, periodically). When the on-off valve 54 is closed, the gas portion accumulates on the primary side of the on-off valve 54, and when the on-off valve 54 is opened, the gas portion is released to the outside of the system. The gas flow path 52 takes a downward path on the secondary side of the on-off valve 54, and then takes a substantially horizontal path.

[0036] The liquid flow path 53 is a flow path that guides the fluid that has flowed out from the secondary side of the inspection filter 4 to the outside of the system. The second pressure gauge 7 and the flow meter 8 are installed at a position in the liquid flow path 53 that is filled with water. The liquid portion that has passed through the flow meter 8 is discharged to the outside of the system.

[0037] The highest point of the liquid flow path 53 is located at a position higher than the highest point of the gas flow path 52. With this configuration, when the on-off valve 54 is opened and the pump 31 is operated, the delivered fluid is guided to the gas flow path 52, facilitating the discharge of gas accumulated in the gas flow path 52 to the outside of the system. This makes it less likely that the fluid guided to the first pressure gauge 6 will contain gas, making it easier for the measurement value of the first pressure gauge 6 to be accurate.

[0038] The first pressure gauge 6 is a pressure gauge that measures the pressure of the fluid upstream of the inspection filter 4. The first pressure gauge 6 is installed on the secondary side of the pump 31 and on the primary side of the inspection filter 4. The measurement value of the first pressure gauge 6 is the inflow pressure to the inspection filter 4.

[0039] The second pressure gauge 7 is a pressure gauge that measures the pressure of the fluid downstream of the inspection filter 4. The second pressure gauge 7 is installed in the liquid flow path 53 on the secondary side of the inspection filter 4. The measurement value of the second pressure gauge 7 is the outflow pressure from the inspection filter 4.

[0040] The flow meter 8 is a pressure meter that measures the flow rate of the fluid downstream of the inspection filter 4. The flow meter 8 is installed in the liquid flow path 53 on the secondary side of the inspection filter 4. The measurement value of the flow meter 8 is the outflow flow rate from the inspection filter 4.

[0041] The first pressure gauge 6 and the second pressure gauge 7 may be known pressure gauges as long as they are capable of electrically transmitting measured values ​​to the computing device 9. Similarly, the flow meter 8 may be known flow meter as long as it is capable of electrically transmitting measured values ​​to the computing device 9.

[0042] The computing device 9 is a computing device that realizes various functions (described later) for evaluating the state of the membrane separation device M. The computing device 9 may be a known computing device, such as, but not limited to, a programmable logic controller (PLC), a microcontroller, a personal computer, etc. The computing device 9 may also be provided with auxiliary devices such as a storage device and a communication device, as appropriate.

[0043] The computing device 9 is electrically connected to the turbidity meter 2, the first pressure gauge 6, the second pressure gauge 7, and the flow meter 8, and can acquire the measured values ​​of each measuring device.

[0044] The computing device 9 is electrically connected to the pump 31 and can control the operation and stopping of the pump 31. The computing device 9 is also electrically connected to the on-off valve 54 and can control the opening and closing of the on-off valve 54.

[0045] [Functions of the Calculation Device and Damage Evaluation Method] Next, functions that can be realized by the evaluation system 1 according to this embodiment and a method for evaluating the state of the membrane separation device M using these functions will be described ( FIG. 3 ). Each function is realized by the calculation device 9. An evaluation program that is one embodiment of the present invention is installed in the calculation device 9. Unless otherwise specified, the calculation device 9 is the entity that executes the operations of each of the following functions.

[0046] To outline the evaluation flow by the evaluation system 1, first, a first evaluation function that performs an evaluation based on the measurement value of the turbidity meter 2 determines whether or not there is a possibility that the membrane separation device M is damaged. If it is determined that there is a possibility of damage, second, a second evaluation function that uses the measurement values ​​of the first pressure gauge 6, the second pressure gauge 7, and the flow meter 8 determines whether or not there is damage to the membrane separation device M.

[0047] Before the flow starts, it may be determined whether the measurement value of the flow meter 8 is within a predetermined range. If this criterion is met, it means that the pump 31 is operating normally and is in a state where evaluation can be performed correctly.

[0048] (1) First Evaluation Function The first evaluation function is a function for evaluating the state of the membrane separation device M based on the measurement value of the turbidity meter 2 (the turbidity of the fluid flowing through the flow path P). If the membrane separation device M is damaged, particles that would normally be captured by the membrane separation device M will flow out to the secondary side of the membrane separation device M, causing an increase in the turbidity of the fluid flowing on the secondary side of the membrane separation device M. Therefore, an upward trend in the measurement value of the turbidity meter 2 indicates the possibility that the membrane separation device M is damaged.

[0049] However, an increase in the measurement value of the turbidity meter 2 can also be caused by factors other than damage to the membrane separation device M. For example, if a fluid containing air bubbles flows into the turbidity meter 2, the measurement value of the turbidity meter 2 will increase due to the air bubbles. With an evaluation based solely on the measurement value of the turbidity meter 2, it is difficult to distinguish between an increase in turbidity caused by damage to the membrane separation device M and an increase in turbidity caused by other factors. Therefore, the first evaluation function evaluates that the membrane separation device M may be damaged when the measurement value of the turbidity meter 2 is on an upward trend, but does not conclude whether the membrane separation device M is damaged or not.

[0050] An example of a determination method in the first evaluation function is shown below. First, the average value of the measurements taken by the turbidimeter 2 over a predetermined period is calculated, and a predetermined constant is added to this average value to set the current reference value. The predetermined constant is set to a value that is sufficiently expected to prevent the measurements taken by the turbidimeter 2 from exceeding the reference value, even when turbidity variations are taken into account, when the turbidity is stable and there are no factors such as damage to the membrane separation device M. For example, when turbidity is expressed in NTU units, the predetermined constant can be a value of approximately 0.05 to 0.1 NTU.

[0051] Next, each instantaneous value of the continuously measured values ​​of the turbidimeter 2 is compared with a reference value. If the instantaneous value does not exceed the reference value for a certain period of time, the reference value is determined again in the same manner as above and updated. The turbidity of the fluid flowing into the turbidimeter 2 can fluctuate depending on the properties of the water to be treated flowing into the membrane separation device M and the operating conditions of the water treatment facility in which the membrane separation device M is installed. The properties of the water to be treated vary depending on various conditions, such as weather, the quality of the wastewater flowing into the treated water treatment facility, the operating conditions of the water treatment facility, and seasonal and temporal variations in the properties of pollutants contained in the water to be treated. Therefore, even if there are no factors such as damage to the membrane separation device M, the measured values ​​of the turbidimeter 2 can gradually fluctuate. By periodically updating the reference value, it is less likely that an incorrect assessment that the membrane separation device M is damaged will occur when the turbidity increases due to changes in the properties of the water to be treated.

[0052] If a state in which the instantaneous value exceeds the reference value is detected at least once, the update of the reference value is first stopped. That is, even if a certain amount of time has passed since the last update of the reference value and the scheduled time for updating the reference value has arrived, the reference value is not updated. Detection of a state in which the instantaneous value exceeds the reference value indicates the possibility of a cause of turbidity increase, such as damage to the membrane separation device M, and updating the reference value in this situation would result in an inaccurate evaluation. Thereafter, the instantaneous value is compared with the reference value while keeping the reference value fixed, and the number of times a state in which the instantaneous value exceeds the reference value is counted. If the number of times exceeds a predetermined threshold within a predetermined time limit, it is determined that the turbidity value is on the rise ( FIG. 3 : S11). On the other hand, if the number of times does not exceed the predetermined threshold within the predetermined time limit, it is determined that the increase in turbidity is due to a temporary factor other than damage to the membrane separation device M (such as the inclusion of air bubbles), and the suspension of updating the reference value is lifted.

[0053] If the first evaluation function evaluates that the membrane separation device M may be damaged, the first timer is started (S12) and the membrane separation device M is evaluated as being in a "warning" state indicating that it may be damaged (S13). The second evaluation function is started. The first timer is used to monitor the duration of the second evaluation function.

[0054] (2) Second evaluation function The second evaluation function is a function for evaluating the state of the membrane separation device M based on the measurement value of the first pressure gauge 6 (inflow pressure to the inspection filter 4), the measurement value of the second pressure gauge 7 (outflow pressure from the inspection filter 4), and the measurement value of the flow meter 8 (outflow flow rate from the inspection filter 4).

[0055] The second evaluation function is implemented when the first evaluation function evaluates that there is a possibility that the membrane separation device M is damaged, and is not implemented under normal circumstances. In each function described below, the time when the pump 31 is started is referred to as t ０ Processing is carried out as follows.

[0056] The evaluation of the state of the membrane separation device M in the second evaluation function is performed through the functions described below.

[0057] (2-1) Water Flow Resistance Identification Function The water flow resistance identification function is a function for identifying the water flow resistance of the inspection filter 4. The water flow resistance R(t) at the time t to be determined is given by the following equation (1). An example of the change in water flow resistance R(t) over time is shown in FIG. 4.

[0058] In formula (1), P １ (t) is the inflow pressure to the inspection filter 4 at the time t to be determined, and is the measurement value of the first pressure gauge 6. ２ (t) is the outflow pressure from the inspection filter 4 at the time t to be evaluated, and is the measurement value of the second pressure gauge 7. C is the difference between the measurement value of the first pressure gauge 6 and the measurement value of the second pressure gauge 7 when the inspection filter 4 is not installed, and is a constant determined during trial operation of the evaluation system 1. F is the outflow flow rate from the inspection filter 4, and in this embodiment, a constant (100 gfd, for example) is set. This constant is determined as the outflow flow rate under the operating conditions by conducting a preliminary experiment to identify the operating conditions of the evaluation system 1 under which linearity in water flow resistance is obtained over a period of one week, for example. S is the area of ​​the inspection filter 4, and is a constant known at the time the inspection filter 4 is installed.

[0059] (2-2) Change Amount Identification Function The change amount identification function is a function for identifying the amount of change in water flow resistance. The change amount ΔR(t) at the time t to be determined is given by the following formula (2-1). An example of the change in the change amount ΔR(t) over time is shown in Figure 5.

[0060] Equation (2-1) specifies the amount of change ΔR(t) using the least squares method. avg. i in equation (2-1) is defined by equation (2-2). avg. R(i) in equation (2-1) is defined by equation (2-3).

[0061] (2-3) Acceleration Index Identification Function The acceleration index identification function is a function for identifying the acceleration index, which is the rate of change in the amount of change in water flow resistance. The acceleration index αR(t) at the time t to be determined is given by the following equation (3). An example of the change in the acceleration index αR(t) over time is shown in Figure 6.

[0062] In equation (3), τ is a predetermined constant. For example, when τ=1 hour (60 minutes), the acceleration index αR(t) at the time t to be determined is determined by dividing the amount of change ΔR(t) at the time t to be determined by the amount of change ΔR(t−τ) at the time t−τ one hour earlier.

[0063] (2-4) Evaluation in the second evaluation function When the acceleration index αR(t) exceeds 1, it indicates that the rate of increase (amount of change ΔR(t)) of the water flow resistance R(t) at the time t being evaluated is larger than that at the time being compared (one hour earlier in the example where τ is one hour). This suggests that clogging of the test filter 4 has progressed compared to the time being compared. In other words, it is suspected that a substance that causes clogging has flowed into the test filter 4, and this is a situation that is sufficient to consider that the membrane separation device M is damaged.

[0064] In this embodiment, the membrane separation device M is evaluated as damaged when the acceleration index αR(t) exceeds 1 for one hour or more. Specifically, the determination is made by looping a comparison of the acceleration index αR(t) with the reference value 1 (FIG. 3: S21) and subsequent processing.

[0065] When the acceleration index αR(t) exceeds 1, the activation status of the second timer is first confirmed (S22). If the second timer is not activated, it is activated (S23), and then the process returns to the comparison of the acceleration index αR(t) with the reference value 1. The second timer is used to monitor the duration of the state in which the acceleration index αR(t) exceeds 1. If the second timer is activated when the acceleration index αR(t) exceeds 1, it is determined whether the count of the second timer exceeds 1 hour (S24). If the count of the second timer does not exceed 1 hour, the process returns to the comparison of the acceleration index αR(t) with the reference value 1. The second timer is reset only when the series of determinations is completed, or only when the acceleration index αR(t) does not exceed 1 (S26). In other words, as long as the acceleration index αR(t) remains in the state in which it exceeds 1, the second timer is not reset and its count continues to increment. If one hour passes without the acceleration index αR(t) exceeding 1 and the count of the second timer exceeds one hour, it is determined that the membrane separation device M is damaged. At this time, it is determined that the membrane separation device M is in an "alarm" state indicating damage (S25).

[0066] If the acceleration index αR(t) does not exceed 1, the second timer is reset (S26). Next, it is determined whether the count of the first timer exceeds 24 hours (S27). If the count of the first timer does not exceed 24 hours, the process returns to the comparison of the acceleration index αR(t) with the reference value 1. If the count of the first timer exceeds 24 hours, the "warning" evaluation in the first evaluation function is canceled (S28). In order to reach a determination in this series of flows that the count of the first timer exceeds 24 hours, 24 hours must pass without the acceleration index αR(t) exceeding 1 continuing for more than one hour. In other words, since no condition that would be evaluated as damage to the membrane separation device M has been observed even after 24 hours of monitoring, it is determined that the "warning" evaluation in the first evaluation function can be canceled. The process then returns to a normal state in which only the first evaluation function is active.

[0067] (3) Notification Function The calculation device 9 notifies the manager of the membrane bioreactor treatment facility of a "warning" (S13 in FIG. 3) in the first evaluation function and an "alarm" (S25) in the second evaluation function. The method for notifying the manager of the warning and alarm is arbitrary, and examples include a physical method using sound, light, vibration, etc., or a method of notifying the manager as information using electromagnetic means such as telephone or e-mail. The evaluation system 1 may include components according to the method for notifying the warning and alarm. That is, the evaluation system 1 may include a physical notification means such as a speaker or lamp, or may be capable of realizing the calculation device 9's function of notifying by electronic means such as e-mail. Note that multiple notification means may be used in combination. Furthermore, the notification means for issuing the warning and the notification means for issuing the alarm may be the same or different.

[0068] [Other Embodiments] Finally, other embodiments of the evaluation system, evaluation method, and evaluation program according to the present invention will be described. Note that the configurations disclosed in the following embodiments can also be applied in combination with the configurations disclosed in other embodiments, as long as no contradiction occurs.

[0069] In the above embodiment, an example has been described in which the second evaluation function is implemented when the first evaluation function evaluates that the membrane separation device M may be damaged. However, the first evaluation function and the second evaluation function may be implemented independently. For example, the order may be reversed from that of the above embodiment, i.e., the second evaluation function may be implemented preferentially, and the first evaluation function may be implemented under certain conditions. Also, both the first evaluation function and the second evaluation function may be implemented at all times.

[0070] In the above embodiment, the second evaluation function performs evaluation based on the acceleration index. However, the method for evaluating the filter condition in the second evaluation function according to the present invention is not limited to this method as long as it is based on the measurement values ​​of the first pressure gauge, the second pressure gauge, and the flow meter.

[0071] In the above embodiment, the inspection filter 4 is provided in a manner that allows dead-end filtration. However, the present invention is not limited to this filtration manner in the inspection filter.

[0072] In the above embodiment, the guide path 5 includes the branch pipe 51, the gas flow path 52, and the liquid flow path 53. However, the present invention is not limited to the form of the flow paths on the primary and secondary sides of the inspection filter.

[0073] In the above embodiment, an example has been described in which the outflow rate F from the inspection filter 4 is used as a constant in the water flow resistance determination function. However, the measurement value F(t) of the flow meter at time t may be used for the outflow rate from the inspection filter 4. In this configuration, the water flow resistance R(t) at time t to be determined is given by the following equation (1a):

[0074] Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention.

[0075] The present invention can be used, for example, to evaluate filtration equipment in sewage treatment plants.

[0076] REFERENCE SIGNS LIST 1: Evaluation system 2: Turbidity meter 21: Lead pipe 3: Water intake pipe 31: Pump 4: Inspection filter 5: Guide path 51: Branch pipe 52: Gas flow path 53: Liquid flow path 54: Opening / closing valve 6: First pressure gauge 7: Second pressure gauge 8: Flow meter 9: Calculation device

Claims

1. An evaluation system that is installed downstream of a filter in a flow path that has a filter and evaluates the condition of the filter, comprising: a turbidity meter that measures the turbidity of a fluid flowing through the flow path; an intake pipe that takes in at least a portion of the fluid flowing through the flow path; an inspection filter that filters the fluid taken in from the intake pipe; a first pressure gauge that measures the pressure of the fluid upstream of the inspection filter; a second pressure gauge that measures the pressure of the fluid downstream of the inspection filter; and a computing device, wherein the computing device is capable of realizing a first evaluation function that evaluates the condition of the filter based on the measurement value of the turbidity meter; and a second evaluation function that evaluates the condition of the filter based on the measurement value of the first pressure gauge and the measurement value of the second pressure gauge.

2. The evaluation system according to claim 1, wherein the second evaluation function is implemented when the first evaluation function evaluates that the filter may be damaged.

3. The evaluation system of claim 1, wherein the arithmetic device is further capable of realizing a water resistance identification function for identifying the water resistance of the test filter, a change amount identification function for identifying the amount of change in the water resistance, and an acceleration index identification function for identifying an acceleration index which is the rate of change in the amount of change, and wherein the second evaluation function evaluates the state of the filter based on the acceleration index at the time to be evaluated.

4. The evaluation system according to claim 1, wherein the inspection filter is a track-edged membrane filter.

5. An evaluation system as described in claim 1, comprising: a branch pipe on the primary side of the inspection filter that guides the liquid portion of the fluid to the inspection filter and guides the gas portion of the fluid to a gas flow path that leads the fluid out of the system; and a liquid flow path that is connected to the secondary side of the inspection filter and leads the liquid portion of the fluid that has passed through the inspection filter out of the system, wherein the gas flow path is at least partially located at a lower position than the liquid flow path.

6. The evaluation system according to claim 1, wherein the inspection filter is disposed so that the primary side of the inspection filter faces directly opposite the flow direction of the fluid taken in from the water intake pipe.

7. An evaluation method for evaluating the state of a filter, which is carried out downstream of a filter in a flow path equipped with the filter, comprising: a turbidity measurement step for measuring the turbidity of a fluid flowing through the flow path; a water intake step for taking in at least a portion of the fluid flowing through the flow path; a filtration step for filtering the fluid taken in in the water intake step using an inspection filter; a first pressure measurement step for measuring the pressure of the fluid upstream of the inspection filter; a second pressure measurement step for measuring the pressure of the fluid downstream of the inspection filter; a first evaluation step for evaluating the state of the filter based on the measured turbidity; and a second evaluation step for evaluating the state of the filter based on the pressure in the first pressure measurement step and the pressure in the second pressure measurement step.

8. An evaluation program for evaluating the state of a filter downstream of a filter in a flow path that includes the filter, which, when executed by a computer, realizes: a first evaluation function for evaluating the state of the filter based on the turbidity of a fluid flowing through the flow path; and a second evaluation function for evaluating the state of the filter based on measured values ​​obtained by filtering at least a portion of the fluid flowing through the flow path through an inspection filter, the measured fluid pressure being measured upstream of the inspection filter and the measured fluid pressure being measured downstream of the inspection filter.

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