Energy-saving and consumption-reducing method for reverse osmosis membrane system

Abstract

The invention discloses an energy-saving and consumption-reducing method for a reverse osmosis membrane system, which belongs to the technical field of water treatment and comprises the following steps: step 1, acquiring various parameter data of the reverse osmosis membrane system in real time; 2, establishing an energy consumption prediction mathematical model of the reverse osmosis membrane system; 3, inputting the real-time parameter data into the energy consumption prediction mathematical model, and judging whether the operation power of the high-pressure pump is reasonable or not according to an output result; 4, when the operation power is not reasonable, the operation power of the high-pressure pump is adjusted in real time; and 5, establishing a membrane pollution concentration early warning model, and carrying out alarm response. According to the method, comprehensive analysis can be carried out in real time according to various parameters of inflow water quality to accurately predict the predicted power, so that whether the set operation power of the high-pressure pump is reasonable or not is judged, the operation power of the high-pressure pump can be dynamically adjusted, the output of energy consumption can be reduced as much as possible under the condition that treatment is qualified, and the operation efficiency of the high-pressure pump is improved. And the cost is saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a method for energy conservation and consumption reduction of a reverse osmosis membrane system. Background Art

[0002] A reverse osmosis membrane system is a high-efficiency water treatment device based on reverse osmosis technology. Its core function is to separate solutes and solvents in a solution under the drive of pressure through the selective permeation of a semi-permeable membrane. It is one of the most advanced and widely used water treatment technologies at present, especially suitable for fields such as seawater desalination, drinking water purification, and industrial ultrapure water preparation.

[0003] When the reverse osmosis membrane system operates, sufficient pressure needs to be applied to overcome the natural osmotic pressure so that water molecules can pass through the semi-permeable membrane while impurities are intercepted. Therefore, a high-pressure pump is required. However, the high-pressure pumps of traditional reverse osmosis membrane systems generally operate fixedly with relatively high energy consumption. The energy consumption of its high-pressure pump accounts for about 40%-60% of the total system energy consumption, and it cannot be dynamically adjusted according to the fluctuation of the influent water quality, making it difficult to timely adjust the operation strategy to adapt to changes, which easily causes waste of energy and increase in operation costs. In addition, the membrane module is easily contaminated by organic matter, colloid, and microorganisms, and the flux decay rate reaches 15%-30% per year, requiring frequent chemical cleaning. However, membrane fouling is unpredictable, and it can only be treated based on experience or set a fixed cleaning cycle, which is not accurate enough and easily causes waste of resources. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for energy conservation and consumption reduction of a reverse osmosis membrane system to solve the problems faced in the above background art.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A method for energy conservation and consumption reduction of a reverse osmosis membrane system, the method comprising: Step 1, collect the influent water quality parameters and the operation parameters of the reverse osmosis membrane system in real time, and perform cleaning, filtering, and normalization processing on the collected parameters to obtain standard parameter data; Step 2, based on a large amount of historical parameter data, use a machine learning algorithm to establish an energy consumption prediction mathematical model of the reverse osmosis membrane system; Step 3, take the parameter data obtained in real time as input and input it into the energy consumption prediction mathematical model to obtain an output result, and judge whether the set operating power of the high-pressure pump of the reverse osmosis membrane system is reasonable according to the output result; Step 4, when it is judged that the operating power is unreasonable, adjust the operating power of the high-pressure pump in real time in combination with the operating target value of the system and the system operation parameters; Step 5: By monitoring and analyzing the membrane performance parameters in real time, establish a membrane fouling concentration early warning model. When the detected membrane fouling degree reaches the early warning threshold, perform corresponding alarm responses.

[0006] Further, the water quality parameters include the conductivity of the influent water quality, the influent water temperature, the influent sludge density index, and the influent water flow rate. The operating parameters include the membrane flux of the permeable membrane and the pre- and post-membrane pressures of the permeable membrane. The operating target values include the water production volume and the desalination rate.

[0007] Further, the method for judging whether the operating power set by the high-pressure pump of the reverse osmosis membrane system is reasonable in Step 3 is as follows: Obtain the conductivity of the influent water quality in real time , the influent water temperature , the influent sludge density index and the influent water flow rate , and substitute them into the energy consumption prediction mathematical model to obtain the predicted power , where is the power conversion coefficient, , , and are their respective weight coefficients; At this time, obtain the operating power set by the high-pressure pump of the reverse osmosis membrane system , if , then judge that the set operating power is reasonable, otherwise judge that the set operating power is unreasonable.

[0008] Further, the method for obtaining the power conversion coefficient is as follows: First, based on the influence of conductivity, influent water temperature, influent sludge density index, and influent water flow rate on energy consumption in historical data, draw up weight coefficients for each according to experience, and obtain n groups of operating data and the corresponding operating power for each group from the database. Substitute each group of operating data and operating power into the energy consumption prediction mathematical model to obtain the predicted power conversion coefficient for each group; Obtain the power conversion coefficient through the formula , where .

[0009] Further, the method for adjusting the operating power of the high-pressure pump in real time in Step 4 is as follows: When the operating power set by the high-pressure pump of the reverse osmosis membrane system is unreasonable, the system generates two instructions at this time. When < 0.9 , generate an increase instruction. When > 1.1 When it is, a reduction instruction is generated.

[0010] Furthermore, the method for real-time adjustment of the operating power of the high-pressure pump in step four further includes: Obtain the membrane flux of the reverse osmosis membrane system , the pre-membrane pressure and the post-membrane pressure , and at the same time obtain the water production and the salt rejection rate required to reach the operating target; When a reduction instruction is generated, reduce the set operating power of the high-pressure pump of the reverse osmosis membrane system by a power magnitude, where ; When an increase instruction is generated, increase the set operating power of the high-pressure pump of the reverse osmosis membrane system by a power magnitude, where ; is the standard membrane flux, is the standard pre-membrane pressure, is the standard post-membrane pressure, is the weight of the influence of the operating parameters, is the weight of the influence of the operating target.

[0011] Furthermore, the working method of step five is: Set an early warning period. During the early warning period, obtain the membrane flux and the inlet water pressure value each time the reverse osmosis membrane system is working, and obtain the degree of membrane fouling through the membrane fouling concentration early warning model ; When , it is determined that the degree of membrane fouling exceeds the threshold, and a corresponding alarm response is carried out; Among them, and are proportionality coefficients, is the membrane flux detected for the first time during the early warning period, is the membrane flux detected for the last time during the early warning period, is the inlet water pressure detected for the first time during the early warning period, is the inlet water pressure detected for the last time during the early warning period, is the first detection point, is the last detection point, is the function of the membrane flux changing with the number of detections formulated according to the membrane flux is the function of the inlet water pressure value Function of the proposed influent pressure value varying with the number of detections is the standard deviation of the membrane flux is the standard deviation of the influent pressure value is the alarm threshold

[0012] Advantages of the present invention The present invention can comprehensively analyze various parameters of the influent water quality in real time to accurately predict the predicted power, so as to judge whether the set operating power of the high-pressure pump is reasonable. In this way, the operating power of the high-pressure pump can be dynamically adjusted, and the energy consumption output can be reduced as much as possible while ensuring qualified treatment, thereby saving costs. At the same time, when adjusting the operating power, the power can be finely adjusted and corrected in combination with the membrane flux of the membrane, the front and back membrane pressures, and the operating target, so as to more accurately adjust the power to ensure the working efficiency of the reverse osmosis membrane system

[0013] This application establishes a membrane fouling concentration early warning model through real-time monitoring and analysis of membrane performance parameters. When it is detected that the degree of membrane fouling reaches the early warning threshold, corresponding alarm responses are made. In this way, the membrane fouling situation of the reverse osmosis membrane system can be warned and monitored, and timely alarm processing can be carried out to prevent the further deterioration of membrane fouling, thereby reducing the energy consumption of the system

[0014] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for describing the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings

[0016] Figure 1 is the flowchart of the method of the present invention DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention

[0018] In one embodiment, a method for energy conservation and consumption reduction of a reverse osmosis membrane system is disclosed. As Figure 1 shown, the method includes Step 1: Collect the inlet water quality parameters and the operating parameters of the reverse osmosis membrane system in real time, and clean, filter, and normalize the collected parameters to obtain standard parameter data. The water quality parameters include the conductivity of the inlet water, the inlet water temperature, the inlet sludge density index, and the inlet water flow rate. The operating parameters include the membrane flux of the permeable membrane and the pre- and post-membrane pressures of the permeable membrane; Step 2: Based on a large amount of historical parameter data, use machine learning algorithms to establish a mathematical model for predicting the energy consumption of the reverse osmosis membrane system; Step 3: Use the parameter data obtained in real time as input and input it into the mathematical model for predicting energy consumption to obtain an output result, and judge whether the set operating power of the high-pressure pump of the reverse osmosis membrane system is reasonable according to the output result; Step 4: When it is judged that the operating power is unreasonable, adjust the operating power of the high-pressure pump in real time in combination with the operating target values of the system and the system operating parameters. The operating target values include the water production rate and the salt rejection rate; Step 5: Through the real-time monitoring and analysis of the membrane performance parameters, establish a membrane fouling concentration warning model, and when it is detected that the degree of membrane fouling reaches the warning threshold, perform corresponding alarm responses.

[0019] Through the above technical solution, the present application first collects the inlet water quality parameters and the operation parameters of the reverse osmosis membrane system in real time, and cleans, filters, and normalizes the collected parameters to obtain standard parameter data, so as to integrate and uniformly calculate various different parameters, which is convenient for subsequent calculation of the mathematical model. Then, based on a large number of historical data parameters, an energy consumption prediction mathematical model of the reverse osmosis membrane system is constructed. Then, the parameter data obtained in real time is used as input and input into the energy consumption prediction mathematical model. The parameter data includes but is not limited to the conductivity of the inlet water quality, the inlet water temperature, the inlet sludge density index, and the inlet water flow rate, so as to obtain the predicted power. According to the obtained predicted power and the actual operating power of the high-pressure pump, it is judged whether the set operating power of the high-pressure pump of the reverse osmosis membrane system is reasonable. When it is unreasonable, the operating power of the high-pressure pump can be adjusted in real time in combination with the operating target value of the system and the system operating parameters; in this way, it can comprehensively analyze various parameters of the inlet water quality in real time to accurately predict the size of the predicted power, so as to judge whether the set operating power of the high-pressure pump is reasonable, so that the power of the high-pressure pump can be dynamically adjusted, and the energy consumption output can be reduced as much as possible while ensuring qualified treatment, thereby saving costs. At the same time, when adjusting the power, the membrane flux of the membrane, the pressure before and after the membrane, and the operating target can also be combined to finely adjust and correct the power, so that the power can be adjusted more accurately to ensure the working efficiency of the reverse osmosis membrane system. In addition, the present application establishes a membrane pollution concentration warning model through real-time monitoring and analysis of membrane performance parameters. When it is detected that the degree of membrane pollution reaches the warning threshold, corresponding alarm responses are made, so that the membrane pollution situation of the reverse osmosis membrane can be warned and monitored, and timely alarm treatment can be carried out to prevent the further deterioration of membrane pollution, thereby reducing the energy consumption of the system.

[0020] The method for judging whether the set operating power of the high-pressure pump of the reverse osmosis membrane system in step three is reasonable is as follows: Obtain the conductivity of the inlet water quality in real time , the inlet water temperature , the inlet sludge density index and the inlet water flow rate , and substitute them into the energy consumption prediction mathematical model to obtain the predicted power , where is the power conversion coefficient, , , and are the respective weight coefficients; At this time, obtain the set operating power of the high-pressure pump of the reverse osmosis membrane system. If , it is judged that the set operating power is reasonable, otherwise it is judged that the set operating power is unreasonable.

[0021] Power conversion coefficient The acquisition method is as follows: First, based on the influence of conductivity, inlet water temperature, inlet sludge density index, and inlet water flow rate on energy consumption in historical data, weight coefficients are assigned to each of them according to experience, and n sets of operation data and the corresponding operation power for each set are obtained from the database. Then, each set of operation data and operation power are substituted into the energy consumption prediction mathematical model to obtain the predicted power conversion coefficient for each set. ; Through the formula The power conversion coefficient is obtained , where .

[0022] The above solution provides a specific method for judging whether the set operation power of the high-pressure pump in the reverse osmosis membrane system is reasonable. Generally speaking, factors such as the conductivity of the inlet water quality, inlet water temperature, inlet sludge density index, and inlet water flow rate will affect the operation power of the high-pressure pump. When the water temperature drops, the conductivity of the water quality is high, the sludge density index is high, and the inlet water flow rate is high, the operation power of the high-pressure pump will increase. Therefore, the conductivity of the inlet water quality is obtained in real time through the corresponding detection equipment 、inlet water temperature 、inlet sludge density index and inlet water flow rate , and they are substituted into the energy consumption prediction mathematical model to obtain the predicted power . At this time, the set operation power of the high-pressure pump in the reverse osmosis membrane system is obtained . If , it is judged that the set operation power is reasonable, otherwise it is judged that the set operation power is unreasonable. If the set operation power fluctuates within 10% above and below the predicted power , it means that the set power is reasonable and no adjustment is required. Otherwise, it means it is unreasonable. To ensure efficiency or reduce energy consumption, the set power needs to be adjusted. Through this method, not only can a comprehensive analysis be carried out based on various parameters of the inlet water quality in real time to accurately predict the magnitude of the predicted power, thereby judging whether the set operation power of the high-pressure pump is reasonable, but also the power of the high-pressure pump can be adjusted dynamically. Under the condition of ensuring qualified treatment, the output of energy consumption can be reduced as much as possible, thus saving costs.

[0023] The method for real-time adjustment of the operation power of the high-pressure pump in step four is as follows: When the set operation power of the high-pressure pump in the reverse osmosis membrane system is unreasonable, the system generates two instructions at this time. When <0.9 , a boost instruction is generated. When >1.1 , a reduction instruction is generated.

[0024] The method for real-time adjustment of the operating power of the high-pressure pump in step four further includes: obtaining the membrane flux of the reverse osmosis membrane system , the pre-membrane pressure and the post-membrane pressure , and at the same time obtaining the water production and the salt rejection rate required to reach the operation target; When a reduction instruction is generated, the set operating power of the high-pressure pump of the reverse osmosis membrane system is reduced by power levels, where ; When an increase instruction is generated, the set operating power of the high-pressure pump of the reverse osmosis membrane system is increased by power levels, where ; is the standard membrane flux, is the standard pre-membrane pressure, is the standard post-membrane pressure, is the influence weight of operating parameters, is the influence weight of operation target.

[0025] Through the above technical solution, this embodiment provides a specific method for real-time adjustment of the operating power of the high-pressure pump. First, when the set operating power of the high-pressure pump of the reverse osmosis membrane system is unreasonable, the operating workpiece is increased or decreased. Therefore, at this time, the system will generate two instructions. When < 0.9 , an increase instruction is generated. When > 1.1 , a reduction instruction is generated. When an instruction is generated, the system will obtain the membrane flux , the pre-membrane pressure and the post-membrane pressure of the reverse osmosis membrane system, and at the same time obtain the water production and the salt rejection rate required to reach the operation target, and when a reduction instruction is generated, the set operating power of the high-pressure pump of the reverse osmosis membrane system is reduced by power levels, where ; when an increase instruction is generated, the set operating power of the high-pressure pump of the reverse osmosis membrane system is increased by power levels, where ; is the standard membrane flux, is the standard pre-membrane pressure, is the standard post-membrane pressure, and all three can be determined according to the qualified data in the historical data, is the influence weight of operating parameters, For the operating target impact weight, it can be determined independently according to experience, but the sum of the two values always equals 1. For example, it can be set as , ; Generally speaking, a high membrane flux will lead to an increase in the pressure drop, thus requiring a higher pre-membrane pressure, and further increasing the power of the high-pressure pump. Moreover, the greater the pre-membrane pressure and post-membrane pressure, the more power is required. In terms of the operating target, the water production rate and the desalination rate are crucial. If the user requires a higher water production rate or a higher desalination rate, then the power of the high-pressure pump needed is greater. Therefore, when adjustment is required, not only can the actual power be analyzed and adjusted based on the difference between the predicted power and the actual power, but the power can also be finely adjusted and corrected by combining the membrane flux of the membrane, the pre- and post-membrane pressure magnitudes, and the operating target. In this way, the power can be adjusted more accurately to ensure the working efficiency of the reverse osmosis membrane system.

[0026] The working method of step five is: Set the warning period. Within the warning period, obtain the membrane flux of the reverse osmosis membrane system each time it is working and the inlet water pressure value , Through the membrane fouling concentration warning model obtain the degree of membrane fouling ; When , it is determined that the degree of membrane fouling exceeds the threshold, and corresponding alarm responses are made.

[0027] Among them, and are proportionality coefficients, is the membrane flux detected for the first time within the warning period, is the membrane flux detected for the last time within the warning period, is the inlet water pressure detected for the first time within the warning period, is the inlet water pressure detected for the last time within the warning period, is the first detection point, is the last detection point, is the function of the membrane flux varying with the number of detections formulated according to the membrane flux , is the function of the inlet water pressure value varying with the number of detections formulated according to the inlet water pressure value , is the standard deviation of the membrane flux, is the standard deviation of the inlet water pressure value, is the alarm threshold.

[0028] The above technical solution provides a specific method for monitoring and warning the degree of membrane fouling. First, set the warning period. Within the warning period, obtain the membrane flux of the reverse osmosis membrane system each time it is working and the inlet water pressure value , and then through the membrane fouling concentration early warning model to obtain the degree of membrane fouling , where and are proportionality coefficients, which are independently determined according to the historical influence ratio combined with experience, but the sum of their values is always equal to 1. For example , , is the membrane flux at the first detection within the warning period, is the membrane flux at the last detection within the warning period, is the inlet water pressure at the first detection within the warning period, is the inlet water pressure at the last detection within the warning period, is the first detection point, is the last detection point, is the function of the membrane flux varying with the number of detections formulated according to the membrane flux , is the function of the inlet water pressure value varying with the number of detections formulated according to the inlet water pressure value , is the standard deviation of the membrane flux, is the standard deviation of the inlet water pressure value, and then compare it with the alarm threshold set according to experience. When , it is determined that the degree of membrane fouling exceeds the threshold, and then corresponding alarm responses are carried out, such as chemical cleaning, etc. In the formula represents the membrane flux decay rate, represents the inlet water pressure growth rate, represents the cumulative change of the membrane flux within the period, represents the cumulative change of the inlet water pressure value within the period. The larger the value, the more serious the membrane fouling; and the larger the standard deviation of the membrane flux or the standard deviation of the inlet water pressure value, the greater the change and fluctuation within the warning period, and the more unstable the membrane performance, which indicates that the membrane fouling is more serious. Therefore, a comprehensive analysis is carried out to obtain the degree of membrane fouling , so as to carry out early warning treatment according to the degree of membrane fouling. In this way, the membrane performance parameters can be monitored and analyzed in real time, so as to carry out early warning monitoring of the membrane fouling situation of the reverse osmosis membrane, and then carry out timely alarm treatment to prevent the further deterioration of membrane fouling, thereby reducing the energy consumption of the system.

[0029] The above content is only an example and explanation of the concept of the present invention. Those skilled in the art of this technology make various modifications or supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the concept of the invention or exceed the scope defined by this claim book, they should all belong to the protection scope of the present invention.

Claims

1. A method for energy conservation and consumption reduction of a reverse osmosis membrane system, characterized in that, The method includes: Step 1: Collect the influent water quality parameters and the operating parameters of the reverse osmosis membrane system in real time, and perform cleaning, filtering, and normalization processing on the collected parameters to obtain standard parameter data; Step 2: Based on a large amount of historical parameter data, use a machine learning algorithm to establish a mathematical model for predicting the energy consumption of the reverse osmosis membrane system; Step 3: Use the parameter data obtained in real time as input and input it into the mathematical model for predicting energy consumption to obtain an output result, and judge whether the set operating power of the high-pressure pump of the reverse osmosis membrane system is reasonable according to the output result; Step 4: When it is judged that the operating power is unreasonable, combine the operating target value of the system and the system operating parameters to adjust the operating power of the high-pressure pump in real time; Step 5: Establish a membrane fouling concentration warning model through real-time monitoring and analysis of the membrane performance parameters, and perform corresponding alarm responses when the detected membrane fouling degree reaches the warning threshold.

2. The energy-saving and consumption-reducing method for a reverse osmosis membrane system according to claim 1, wherein, The water quality parameters include the influent water conductivity, influent water temperature, influent sludge density index, and influent flow rate. The operating parameters include the membrane flux of the permeable membrane and the pre- and post-membrane pressures of the permeable membrane. The operating target values include the water production rate and the desalination rate.

3. A method for energy conservation and consumption reduction of a reverse osmosis membrane system according to claim 2, characterized in that, The method for judging whether the set operating power of the high-pressure pump of the reverse osmosis membrane system is reasonable in Step 3 is: Obtain the conductivity of the influent water quality in real time , the influent water temperature , the influent sludge density index and the influent flow rate , and substitute them into the energy consumption prediction mathematical model to obtain the predicted power , where is the power conversion coefficient, , , and are the respective weight coefficients; At this time, obtain the set operating power of the high-pressure pump of the reverse osmosis membrane system , if , it is determined that the set operating power is reasonable, otherwise it is determined that the set operating power is unreasonable.

4. A method for energy conservation and consumption reduction of a reverse osmosis membrane system according to claim 3, characterized in that, The power conversion coefficient The acquisition method is as follows: First, based on the influence of conductivity, influent water temperature, influent sludge density index, and influent flow rate on energy consumption in historical data, weight coefficients are assigned to each according to experience, and n sets of operating data and the corresponding operating power for each set are obtained from the database. Each set of operating data and operating power is substituted into the energy consumption prediction mathematical model to obtain the predicted power conversion coefficient for each set ; The power conversion coefficient is obtained through the formula where and .

5. A method for energy conservation and consumption reduction of a reverse osmosis membrane system according to claim 4, characterized in that, The method for adjusting the operating power of the high-pressure pump in real time in Step 4 is: When the operating power set by the high-pressure pump of the reverse osmosis membrane system is unreasonable, the system generates two types of instructions at this time. When <0.9 , a boost instruction is generated. When >1.1 , a reduction instruction is generated.

6. A method for energy conservation and consumption reduction of a reverse osmosis membrane system according to claim 5, characterized in that, The method for adjusting the operating power of the high-pressure pump in real time in Step 4 also includes: Obtain the membrane flux of the reverse osmosis membrane system , the pre-membrane pressure and the post-membrane pressure , and at the same time obtain the water production required to achieve the operation target and the salt rejection rate ; When generating a reduction instruction, reduce the operating power set by the high-pressure pump of the reverse osmosis membrane system by power levels, where ; When generating an improvement instruction, increase the operating power set by the high-pressure pump of the reverse osmosis membrane system by power levels, where ; is the standard membrane flux, is the standard pre-membrane pressure, is the standard post-membrane pressure, is the weight of the influence of operating parameters, is the weight of the influence of operating objectives.

7. A method for energy conservation and consumption reduction of a reverse osmosis membrane system according to claim 6, characterized in that, The working method of Step 5 is: Set an early warning period. During the early warning period, obtain the membrane flux of the reverse osmosis membrane system each time it is operating and the inlet water pressure value , Through the membrane fouling concentration early warning model Obtain the degree of membrane fouling ; When it is determined that the degree of membrane fouling exceeds the threshold, a corresponding alarm response is carried out; Among them, and are proportionality coefficients, is the membrane flux detected for the first time within the warning period, is the membrane flux detected for the last time within the warning period, is the inlet water pressure detected for the first time within the warning period, is the inlet water pressure detected for the last time within the warning period, is the first detection point, is the last detection point, is the function of the membrane flux varying with the number of detections formulated according to the membrane flux , is the function of the inlet water pressure value varying with the number of detections formulated according to the inlet water pressure value , is the standard deviation of the membrane flux, is the standard deviation of the inlet water pressure value, is the alarm threshold.

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