CN113283481A - Intelligent membrane pollution decision-making method based on knowledge type-two fuzzy - Google Patents
Intelligent membrane pollution decision-making method based on knowledge type-two fuzzy Download PDFInfo
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Abstract
The invention provides a knowledge-based two-type fuzzy membrane pollution intelligent decision method aiming at the problem that the membrane pollution is difficult to accurately decide in the MBR urban sewage treatment process so as to reduce the occurrence of membrane pollution; the method summarizes the prior experience knowledge in the MBR sewage treatment plant, and establishes a membrane pollution decision knowledge base in a fuzzy rule form; initializing parameter design of affiliation layers of the interval two-type fuzzy neural network model by using fuzzy rules, and completing parameter adjustment of the model by using a migration gradient descent algorithm to improve the learning performance of the model; by providing accurate operation suggestions for membrane pollution, the membrane pollution decision-making precision is improved, the membrane pollution is slowed down, and the stable operation of the MBR municipal sewage treatment process is promoted.
Description
Technical Field
The invention realizes the decision of membrane pollution in the MBR municipal sewage treatment process by using a knowledge-based two-type fuzzy method so as to reduce the occurrence of membrane pollution. A decision-making method based on data and knowledge is applied to a nonlinear MBR sewage treatment system, an operation suggestion is provided for membrane pollution, stable and safe operation of an MBR municipal sewage treatment process is guaranteed, and the method belongs to the technical field of sewage treatment and also belongs to the field of intelligent decision-making. Therefore, intelligent decision making of membrane fouling is of great significance in sewage treatment systems.
Background
The '2020 world water development report' issued by the united nations water system indicates that: the global water consumption is increased by about six times compared with the past 100 years at present, and the value is still steadily increased by 1% per year along with the increase of population, economic development and change of consumption mode. According to the forecast of water conservancy departments, the total water shortage in China will reach 600 billions of cubic meters in 2040 years along with the increase of the total population, and the per capita water resource will be reduced to 1630 cubic meters. The water resource shortage and water pollution crisis are basic problems restricting the sustainable development of social economy and are problems to be solved urgently in the water environment treatment process of China. The recycling of the urban sewage can effectively relieve the problems of water resource shortage, water resource waste and the like. How to improve the urban sewage treatment capacity and level is one of the research focuses on realizing the continuous utilization of water resources, relieving the shortage of water resources and building a water-saving society.
The MBR sewage treatment process is a novel sewage treatment technology combining a high-efficiency membrane separation technology and a traditional activated sludge process, and is recognized by all countries in the world as one of the most potential development technologies in the field of water treatment in the twenty-first century. The MBR technology can achieve higher nutrient removal efficiency and complete biomass retention without secondary clarification, and improves the sewage treatment capacity and efficiency. With the continuous maturity of membrane technology, MBR sewage treatment process is more and more widely applied in municipal sewage treatment. However, the membrane pollution problem is inevitable, which may result in increased operation energy consumption, reduced life of the MBR, and even paralysis of the whole sewage treatment process, which is one of the most widespread problems hindering stable application of the MBR.
With the rapid development of information technology, the establishment of intelligent water treatment plants is called the trend of future development of sewage treatment plants, and how to establish an intelligent decision system becomes a hot problem. Therefore, the research of an intelligent membrane pollution decision method is very important for reducing the occurrence of membrane pollution, ensuring the stable operation of the MBR sewage treatment process and improving the intelligent level of a sewage treatment plant. In the actual operation of the MBR, the decision of membrane fouling is often made through the experience of water plant workers, often based on time periods or values of individual process variables, to derive the cleaning method or replacement speed of the MBR, and is not scientific and comprehensive. Membrane fouling is a dynamic, uncertain process, and operators in different water plants have different preferences and lack reasonable decision-making criteria. The decision-making method of how to comprehensively select membrane fouling using values of multiple process variables has attracted attention. In addition, when the data volume of the membrane fouling decision is insufficient, it is difficult to achieve an accurate decision. How to apply the knowledge of the operators in the actual water plant to the decision algorithm is also an urgent problem to be solved. An effective membrane pollution intelligent decision-making method is designed, and the method has higher research significance and application value for inhibiting the occurrence of membrane pollution and ensuring the long-term stable operation of the MBR municipal sewage treatment process.
Disclosure of Invention
The invention designs a knowledge-based two-type fuzzy membrane pollution intelligent decision method, which summarizes and expresses membrane pollution decision knowledge, adopts a knowledge-based interval two-type fuzzy neural network model, adopts a migration gradient descent algorithm to complete the parameter update of the model, and realizes the accurate decision of membrane pollution.
The invention adopts the following technical scheme and implementation steps:
a data and knowledge based decision method comprising the steps of:
the method comprises the following steps: acquiring variable data of a membrane pollution process:
gather membrane pollution process data through MBR sewage treatment instrument, including 8 key variables: water permeability, water permeability attenuation speed, water production flow, membrane scrubbing air flow, sludge concentration, transmembrane pressure difference, water production turbidity and water permeability recovery rate;
step two: knowledge expression of membrane pollution process:
combining historical data of membrane pollution process variables with decision-making knowledge of actual operation in a water plant, defining the data as a source scene, wherein fuzzy rules about membrane pollution decisions are shown in a table 1;
TABLE 1 fuzzy rules for film fouling decision
Table.1 Membrane fouling decision fuzzy rules
According to the MBR membrane system operation manual, the MBR membrane cleaning maintenance manual, the urban sewage treatment and pollution prevention and control technical strategy and other relevant use specifications and laws and regulations, and in combination with the actual cleaning strategy of a sewage treatment plant, the membrane pollution decision-making method is divided into the following methods:
secondly, the operation in the current state is not suitable for more than 4 hours, and the on-line chemical cleaning is needed in time after the overload operation;
secondly, physical cleaning is carried out in the near term;
thirdly, closing the water production system and carrying out off-line cleaning as soon as possible;
fourthly, the water yield is reduced to 260m3Performing off-line cleaning below the/h;
fifth, close the water producing system or increase the aeration rate to 3000m3More than h;
reducing the opening of the valve of the aeration pipeline;
seventhly, increasing the aeration quantity to 4500m3More than h, or reducing the water yield to 260m3H and below;
eighthly, whether the water quality, the water production flow, the membrane scrubbing air quantity and the membrane tank sludge concentration are abnormal is checked;
ninthly, checking a leakage membrane module device and a water production pipeline;
increasing the sludge discharge amount of the membrane tank, increasing the reflux ratio of the membrane tank, and controlling the sludge concentration of the membrane tank to be 8000-charge 12000 mg/L;
reducing the water yield of the membrane pool, and controlling the transmembrane pressure difference to be less than 40 kPa;
reducing the discharge amount of the residual sludge, checking the sludge reflux ratio, and controlling the sludge concentration of the membrane tank to be more than 6000 mg/L;
paying attention to the operation condition of the membrane pool, and performing online chemical cleaning (large cleaning) again within 72 hours;
summarize these decision information into fuzzy rules
Wherein,is the water penetration rate of the source scene at time t,is the water permeability decay rate of the source scene at time t,is the water production flow rate of the source scenario at time t,is the amount of membrane scrub gas for the source scene at time t,is the sludge concentration of the source scene at time t,(t) is the transmembrane pressure difference of the source scene at time t,is the water production turbidity of the source scene at time t,is the water permeability recovery rate of the source scene at time t, S represents the source scene,is the linguistic item of the u input variable in the b fuzzy rule of the source scene at the time t,is the output of the b-th fuzzy rule of the source scene at the time t, namely the membrane fouling decision category,the decision result of the linguistic item and the membrane pollution output by the b-th fuzzy rule of the source scene at the time t, u is the number of input variables, b is the number of fuzzy rules, and u is 1, …, 8, b is 1, …, 13;
step three: interval two-type fuzzy neural network based on migration gradient descent:
the interval type two fuzzy neural network has 5 layers which are respectively an input layer, a membership function layer, a rule layer, a back part layer and an output layer, and the mathematical description is as follows:
an input layer: a total of 8 neurons, with the output of the input layer being
ru(t)=xu(t) (2)
X(t)=[x1(t),x2(t),x3(t),x4(t),x5(t),x6(t),x7(t),x8(t)] (3)
Wherein r isu(t) is the output of the u-th input neuron of the two-type fuzzy neural network in the t time interval, xu(t) is the input value of the u-th process variable at the time t, X (t) is the input vector of the two-type fuzzy neural network in the interval of the time t, x1(t) is an input value of water permeability at time t, x2(t) is an input value of a permeable rate attenuation rate at time t, x3(t) is an input value of the water production flow at time t, x4(t) is the input value of the amount of membrane scrubbing gas at time t, x5(t) is an input value of sludge concentration at time t, x6(t) is the input value of the transmembrane pressure difference at time t, x7(t) is the input value of the turbidity of the produced water at time t, x8(t) is an input value of the water permeability recovery rate at time t;
membership function layer: a total of 8 × 13 neurons, with the output of the membership function layer being
Wherein,is the output of the b-th membership function layer neuron at the u-th input at time t, cub(t) is the center of the mth input, the b-th membership function layer neuron at time t, σub(t) is the width of the mth input, the b-th membership function layer neuron at time t,andrespectively an upper bound and a lower bound of the u membership function in the b fuzzy rule of the source scene at the time t, cub(t) andrespectively inputting the lower bound and the upper bound of the central value of the b-th membership function layer neuron at the u-th time, wherein e is a natural constant, and is 2.7183, and the interval form of the membership function layer neuron is
Wherein,andthe lower bound and the upper bound of the output of the b-th input membership function layer neuron at the time t are respectively set;
and (3) a rule layer: there are 13 neurons in total, with the output of the rule layer being
Wherein v isb(t) is the output of the b-th regular layer neuron at time t, vb(t) andthe lower bound and the upper bound of the output of the b-th rule layer neuron at the time t respectively;
a rear part layer: there are 26 neurons in total, the output of the back-end layer is
Wherein,is the back-part weight for the b-th regular layer neuron and the g-th output layer neuron at time t,is the weight coefficient of the u-th input neuron, the b-th rule layer neuron and the g-th output neuron at the time t, yg(t) andthe output lower bound and the output upper bound of the back part layer neuron of the g-th output layer neuron at the time t are respectively, and g is 1, 2, … and 13;
an output layer: there are 13 neurons in total, the output of the output layer is
Wherein, yg(t) is the g-th output value, gamma, of the two-type fuzzy neural network in the t-time intervalg(t) is the ratio of the lower bound of the back-part layer neurons of the g-th output layer neuron at time t;
the normalized exponential function model is mainly used for solving the multi-classification problem, and the probability p (y (t) ═ G) is set to represent the probability that the membrane pollution sample is judged to be the class G at the time t, the probability with the maximum output is selected as the final class, and the output of the class G classification is
Wherein h (t) is the output probability vector of the two-type fuzzy neural network model in the t-time interval, y (t) is the classification category of the model at the t time, and k is a normalization function, so that the sum of all probabilities is 1;
in order to improve the learning performance of the interval two-type fuzzy neural network model, a migration gradient descent algorithm is provided, and the knowledge of a source model and the data of a target model are combined in the learning process; the steps of the migration gradient descent algorithm are as follows: in the learning process, extracting a series of knowledge from film pollution decision history data of a source scene, and transferring the knowledge to a target scene;
defining an objective function of the model as
Where E (t) is the objective function at time t, D represents the target scene, f0 DIs a regional two-type fuzzy neural network function, x, of the target sceneD(t) is the input of the target model at time t, wnew(t) is the back-end layer output weight parameter of the target model at time t,is the expected output of the target model at time t
wnew(t)=wold(t)+δ(t)wS(tθ) (21)
Wherein, wold(t) is the back-end layer initial output weight of the target model at time t, wS(t) is the source model back-part layer output weight at time t, δ (t) is the balance parameter at time t, 0<δ(t)<1, representing the relation between a target model and a source model;
in the interval two-type fuzzy neural network model, three variables are updated: the target model back-part layer output weight, the source model back-part layer output weight and the balance parameter are updated according to the following formula
Wherein, wS(t +1) is the source model back-end-of-layer output weight at time t +1, η1Is the learning rate of the source model back-end output weights,is the partial derivative, w, of the target function at time t with respect to the source model back-part layer output weightD(t +1) is the target model back-end output weight at time t +1, wD(t) is the target model back-end layer output weight at time t, η2Is the learning rate of the target model's back-end output weights,is the partial derivative of the target function at the time t with respect to the output weight of the target model back-part layer, δ (t +1) is the equilibrium parameter at the time t +1, η3Is the learning rate of the balance parameter,is the partial derivative of the objective function with respect to the balance parameter at time t. In the scheme, in the step one: collecting membrane pollution key process variables through an MBR sewage treatment instrument;
in the second step: the membrane pollution process knowledge represents the combination of membrane pollution process variable historical data and decision-making knowledge of actual operation in a water plant, and the third step is as follows: and (3) modeling the membrane pollution by adopting an interval two-type fuzzy neural network, and updating network model parameters by adopting a migration gradient descent algorithm.
Compared with the prior art, the invention has the following advantages: 1) the invention provides a knowledge-based interval type two fuzzy neural network decision model aiming at the problem that the membrane pollution phenomenon is difficult to accurately identify due to nonlinear and timely complex characteristics in the membrane pollution process, and the construction of an intelligent membrane pollution decision model is completed by converting decision knowledge in the operation process into a fuzzy rule form and designing a membership function by using the fuzzy rule, so that the decision on the membrane pollution is realized; 2) in order to improve the precision of a membrane pollution decision model, the invention designs a migration gradient descent algorithm to carry out self-adaptive updating on model parameters, extracts a series of knowledge from membrane pollution decision history data of a source scene, transfers the knowledge to a target scene to complete the updating of the decision model parameters, realizes the accurate decision of membrane pollution, slows down the occurrence of membrane pollution and promotes the stable operation of the MBR municipal sewage treatment process.
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FIG. 1 is a block diagram of a knowledge-based two-type fuzzy membrane fouling intelligent decision method.
Detailed Description
For a better understanding and appreciation of the invention, reference will now be made in detail to the embodiments illustrated in the accompanying drawings.
Example 1: referring to fig. 1, a knowledge-based two-type fuzzy membrane fouling intelligent decision method, the method comprising the steps of:
the method comprises the following steps: acquiring variable data of a membrane pollution process:
step two: knowledge expression of membrane pollution process:
step three: the interval type two fuzzy neural network based on migration gradient descending.
According to the on-line sensor who installs in MBR sewage treatment system in this scheme, gather membrane pollution process data, including 8 key variables: water permeability, water permeability attenuation speed, water production flow, membrane scrubbing air flow, sludge concentration, transmembrane pressure difference, water production turbidity and water permeability recovery rate.
In the second step, the knowledge expression of the membrane pollution process is realized, and the method comprises the following steps:
combining historical data of membrane pollution process variables with decision-making knowledge of actual operation in a water plant, defining the data as a source scene, wherein fuzzy rules about membrane pollution decisions are shown in a table 1;
TABLE 1 fuzzy rules for film fouling decision
Table.1 Membrane fouling decision fuzzy rules
According to the MBR membrane system operation manual, the MBR membrane cleaning maintenance manual, the urban sewage treatment and pollution prevention and control technical strategy and other relevant use specifications and laws and regulations, and in combination with the actual cleaning strategy of a sewage treatment plant, the membrane pollution decision-making method is divided into the following methods:
firstly, the operation in the current state is not suitable for more than 4 hours, and the online chemical cleaning is needed in time after the overload operation;
secondly, physical cleaning is carried out in the near term;
thirdly, closing the water production system and carrying out off-line cleaning as soon as possible;
fourthly, the water yield is reduced to 260m3Performing off-line cleaning below the/h;
fifth, close the water producing system or increase the aeration rate to 3000m3More than h;
reducing the opening of the valve of the aeration pipeline;
seventhly, increasing the aeration quantity to 4500m3More than h, or reducing the water yield to 260m3H and below;
eighthly, whether the water quality, the water production flow, the membrane scrubbing air quantity and the membrane tank sludge concentration are abnormal is checked;
ninthly, checking a leakage membrane module device and a water production pipeline;
increasing the sludge discharge amount of the membrane tank, increasing the reflux ratio of the membrane tank, and controlling the sludge concentration of the membrane tank to be 8000-charge 12000 mg/L;
reducing the water yield of the membrane pool, and controlling the transmembrane pressure difference to be less than 40 kPa;
reducing the discharge amount of the residual sludge, checking the sludge reflux ratio, and controlling the sludge concentration of the membrane tank to be more than 6000 mg/L;
paying attention to the operation condition of the membrane pool, and performing online chemical cleaning again within 72 hours;
summarize these decision information into fuzzy rules
Wherein,is the water penetration rate of the source scene at time t,is the water permeability decay rate of the source scene at time t,is the water production flow rate of the source scenario at time t,is the amount of membrane scrub gas for the source scene at time t,is the sludge concentration of the source scene at time t, is the transmembrane pressure difference of the source scene at time t,is the water production turbidity of the source scene at time t,is the water permeability recovery rate of the source scene at time t, S represents the source scene,is the linguistic item of the u input variable in the b fuzzy rule of the source scene at the time t,is the output of the b-th fuzzy rule of the source scene at the time t, namely the membrane fouling decision category,the decision result of the linguistic item and the membrane fouling output by the b-th fuzzy rule of the source scene at the time t, u is the number of input variables, b is the number of fuzzy rules, and u is 1, …, 8, b is 1, …, 13.
In the third step, constructing an interval type two fuzzy neural network model based on migration gradient descent, which comprises the following steps:
the interval type two fuzzy neural network has 5 layers which are respectively an input layer, a membership function layer, a rule layer, a back part layer and an output layer, and the mathematical description is as follows:
an input layer: a total of 8 neurons, with the output of the input layer being
ru(t)=xu(t); (24)
X(t)=[x1(t),x2(t),x3(t),x4(t),x5(t),x6(t),x7(t),x8(t)] (25)
Wherein r isu(t) is the output of the u-th input neuron of the two-type fuzzy neural network in the t time interval, xu(t) is the input value of the u-th process variable at the time t, X (t) is the input vector of the two-type fuzzy neural network in the interval of the time t, x1(t) is an input value of water permeability at time t, x2(t) is an input value of a permeable rate attenuation rate at time t, x3(t) is an input value of the water production flow at time t, x4(t) is the input value of the amount of membrane scrubbing gas at time t, x5(t) is an input value of sludge concentration at time t, x6(t) is the input value of the transmembrane pressure difference at time t, x7(t) is the input value of the turbidity of the produced water at time t, x8(t) is an input value of the water permeability recovery rate at time t;
membership function layer: a total of 8 × 13 neurons, with the output of the membership function layer being
Wherein,is the output of the b-th membership function layer neuron at the u-th input at time t, cub(t) is the center of the mth input, the b-th membership function layer neuron at time t, σub(t) is the width of the mth input, the b-th membership function layer neuron at time t,andrespectively an upper bound and a lower bound of the u membership function in the b fuzzy rule of the source scene at the time t, cub(t) andrespectively inputting the lower bound and the upper bound of the central value of the b-th membership function layer neuron at the u-th time, wherein e is a natural constant, and is 2.7183, and the interval form of the membership function layer neuron is
Wherein,andthe lower bound and the upper bound of the output of the b-th input membership function layer neuron at the time t are respectively set;
and (3) a rule layer: there are 13 neurons in total, with the output of the rule layer being
Wherein v isb(t) is the output of the b-th regular layer neuron at time t, vb(t) andrespectively, below the output of the b-th regular layer neuron at time tA bound and an upper bound;
a rear part layer: there are 26 neurons in total, the output of the back-end layer is
Wherein,is the back-part weight for the b-th regular layer neuron and the g-th output layer neuron at time t,is the weight coefficient of the u-th input neuron, the b-th rule layer neuron and the g-th output neuron at the time t, yg(t) andthe output lower bound and the output upper bound of the back part layer neuron of the g-th output layer neuron at the time t are respectively, and g is 1, 2, … and 13;
an output layer: there are 13 neurons in total, the output of the output layer is
Wherein, yg(t) is the g-th output value, gamma, of the two-type fuzzy neural network in the t-time intervalg(t) is the ratio of the lower bound of the back-part layer neurons of the g-th output layer neuron at time t;
the normalized exponential function model is mainly used for solving the multi-classification problem, and the probability p (y (t) ═ G) is set to represent the probability that the membrane pollution sample is judged to be the class G at the time t, the probability with the maximum output is selected as the final class, and the output of the class G classification is
Where h (t) is the output probability vector of the two type fuzzy neural network model in the t time interval, y (t) is the classification category of the model at the t time, and k is the normalization function, so that the sum of all probabilities is 1.
Updating network model parameters by using a migration gradient descent algorithm, extracting a series of knowledge from membrane pollution decision history data of a source scene in a learning process, and transferring the knowledge into a target scene;
defining an objective function of the model as
Where E (t) is the objective function at time t, D represents the target scene, f0 DIs a regional two-type fuzzy neural network function, x, of the target sceneD(t) is the input of the target model at time t, wnew(t) is the back-end layer output weight parameter of the target model at time t,is the expected output of the target model at time t
wnew(t)=wold(t)+δ(t)wS(tθ) (43)
Wherein,wold(t) is the back-end layer initial output weight of the target model at time t, wS(t) is the source model back-part layer output weight at time t, δ (t) is the balance parameter at time t, 0<δ(t)<1, representing the relation between a target model and a source model;
in the interval two-type fuzzy neural network model, three variables are updated: the target model back-part layer output weight, the source model back-part layer output weight and the balance parameter are updated according to the following formula
Wherein, wS(t +1) is the source model back-end-of-layer output weight at time t +1, η1Is the learning rate of the source model back-end output weights,is the partial derivative, w, of the target function at time t with respect to the source model back-part layer output weightD(t +1) is the target model back-end output weight at time t +1, wD(t) is the target model back-end layer output weight at time t, η2Is the learning rate of the target model's back-end output weights,is the partial derivative of the target function at the time t with respect to the output weight of the target model back-part layer, δ (t +1) is the equilibrium parameter at the time t +1, η3Is the learning rate of the balance parameter,is the partial derivative of the objective function with respect to the balance parameter at time t.
It should be noted that the above-mentioned embodiments are not intended to limit the scope of the present invention, and all equivalent modifications and substitutions based on the above-mentioned technical solutions are within the scope of the present invention as defined in the claims.
Claims (8)
1. A knowledge-based intelligent membrane pollution decision method based on two-type fuzzy is characterized by comprising the following steps:
the method comprises the following steps: acquiring variable data of a membrane pollution process:
step two: knowledge expression of membrane pollution process:
step three: the interval type two fuzzy neural network based on migration gradient descending.
2. The intelligent knowledge-based two-type fuzzy membrane fouling decision making method according to claim 1, characterized by comprising the following steps: acquiring variable data of a membrane pollution process, which comprises the following steps:
gather membrane pollution process data through MBR sewage treatment instrument, including 8 key variables: water permeability, water permeability attenuation speed, water production flow, membrane scrubbing air flow, sludge concentration, transmembrane pressure difference, water production turbidity and water permeability recovery rate.
3. The intelligent knowledge-based two-type fuzzy membrane fouling decision making method according to claim 1, characterized by the following steps: knowledge expression of membrane pollution process: the method comprises the following specific steps:
combining historical data of membrane pollution process variables with decision-making knowledge of actual operation in a water plant, defining the data as a source scene, wherein fuzzy rules about membrane pollution decisions are shown in a table 1;
TABLE 1 fuzzy rules for film fouling decision
According to the MBR membrane system operation manual, the MBR membrane cleaning maintenance manual, the urban sewage treatment and pollution prevention and control technical strategy and other relevant use specifications and laws and regulations, and in combination with the actual cleaning strategy of a sewage treatment plant, the membrane pollution decision-making method is divided into the following methods:
firstly, the operation in the current state is not suitable for more than 4 hours, and the online chemical cleaning is needed in time after the overload operation;
secondly, physical cleaning is carried out in the near term;
thirdly, closing the water production system and carrying out off-line cleaning as soon as possible;
fourthly, the water yield is reduced to 260m3Performing off-line cleaning below the/h;
fifth, close the water producing system or increase the aeration rate to 3000m3More than h;
reducing the opening of the valve of the aeration pipeline;
seventhly, increasing the aeration quantity to 4500m3More than h, or reducing the water yield to 260m3H and below;
eighthly, whether the water quality, the water production flow, the membrane scrubbing air quantity and the membrane tank sludge concentration are abnormal is checked;
ninthly, checking a leakage membrane module device and a water production pipeline;
increasing the sludge discharge amount of the membrane tank, increasing the reflux ratio of the membrane tank, and controlling the sludge concentration of the membrane tank to be 8000-charge 12000 mg/L;
reducing the water yield of the membrane pool, and controlling the transmembrane pressure difference to be less than 40 kPa;
reducing the discharge amount of the residual sludge, checking the sludge reflux ratio, and controlling the sludge concentration of the membrane tank to be more than 6000 mg/L;
paying attention to the operation condition of the membrane pool, and performing online chemical cleaning again within 72 hours;
summarize these decision information into fuzzy rules
Wherein,is the water penetration rate of the source scene at time t,is the water permeability decay rate of the source scene at time t,is the water production flow rate of the source scenario at time t,is the amount of membrane scrub gas for the source scene at time t,is the sludge concentration of the source scene at time t,(t) is the transmembrane pressure difference of the source scene at time t,is the water production turbidity of the source scene at time t,is the water permeability recovery rate of the source scene at time t, S represents the source scene,is the linguistic item of the u input variable in the b fuzzy rule of the source scene at the time t,is the output of the b-th fuzzy rule of the source scene at the time t, namely the membrane fouling decision category,is the language term and membrane pollution output by the b-th fuzzy rule of the source scene at the time tAs a result of the decision, u is the number of input variables, b is the number of fuzzy rules, u is 1, …, 8, and b is 1, …, 13.
4. The intelligent knowledge-based two-type fuzzy membrane fouling decision making method according to claim 1, characterized by comprising the following three steps: the interval type two fuzzy neural network based on migration gradient descent specifically comprises the following steps:
the interval type two fuzzy neural network has 5 layers which are respectively an input layer, a membership function layer, a rule layer, a back part layer and an output layer, and the mathematical description is as follows:
an input layer: a total of 8 neurons, with the output of the input layer being
ru(t)=xu(t); (2)
X(t)=[x1(t),x2(t),x3(t),x4(t),x5(t),x6(t),x7(t),x8(t)] (3)
Wherein r isu(t) is the output of the u-th input neuron of the two-type fuzzy neural network in the t time interval, xu(t) is the input value of the u-th process variable at the time t, X (t) is the input vector of the two-type fuzzy neural network in the interval of the time t, x1(t) is an input value of water permeability at time t, x2(t) is an input value of a permeable rate attenuation rate at time t, x3(t) is an input value of the water production flow at time t, x4(t) is the input value of the amount of membrane scrubbing gas at time t, x5(t) is an input value of sludge concentration at time t, x6(t) is the input value of the transmembrane pressure difference at time t, x7(t) is the input value of the turbidity of the produced water at time t, x8(t) is an input value of the water permeability recovery rate at time t;
membership function layer: a total of 8 × 13 neurons, with the output of the membership function layer being
Wherein,is the output of the b-th membership function layer neuron at the u-th input at time t, cub(t) is the center of the mth input, the b-th membership function layer neuron at time t, σub(t) is the width of the mth input, the b-th membership function layer neuron at time t,andrespectively an upper bound and a lower bound of the u membership function in the b fuzzy rule of the source scene at the time t, cub(t) andrespectively inputting the lower bound and the upper bound of the central value of the b-th membership function layer neuron at the u-th time, wherein e is a natural constant, and is 2.7183, and the interval form of the membership function layer neuron is
Wherein,andthe lower bound and the upper bound of the output of the b-th input membership function layer neuron at the time t are respectively set; and (3) a rule layer: there are 13 neurons in total, with the output of the rule layer being
Wherein v isb(t) is the output of the b-th regular layer neuron at time t, vb(t) andthe lower bound and the upper bound of the output of the b-th rule layer neuron at the time t respectively;
a rear part layer: there are 26 neurons in total, the output of the back-end layer is
Wherein,is the back-part weight for the b-th regular layer neuron and the g-th output layer neuron at time t,is the weight coefficient of the u-th input neuron, the b-th rule layer neuron and the g-th output neuron at the time t, yg(t) andthe output lower bound and the output upper bound of the back part layer neuron of the g-th output layer neuron at the time t are respectively, and g is 1, 2, … and 13;
an output layer: there are 13 neurons in total, the output of the output layer is
Wherein, yg(t) is the g-th output value, gamma, of the two-type fuzzy neural network in the t-time intervalg(t) is the ratio of the lower bound of the back-part layer neurons of the g-th output layer neuron at time t;
the normalized exponential function model is mainly used for solving the multi-classification problem, and the probability p (y (t) ═ G) is set to represent the probability that the membrane pollution sample is judged to be the class G at the time t, the probability with the maximum output is selected as the final class, and the output of the class G classification is
Where h (t) is the output probability vector of the two type fuzzy neural network model in the t time interval, y (t) is the classification category of the model at the t time, and k is the normalization function, so that the sum of all probabilities is 1.
5. The intelligent knowledge-based two-type fuzzy membrane fouling decision making method according to claim 1, wherein the step of the migration gradient descent algorithm in the step three is as follows: in the learning process, extracting a series of knowledge from film pollution decision history data of a source scene, and transferring the knowledge to a target scene;
defining an objective function of the model as
Where E (t) is the objective function at time t, D represents the target scene, f0 DIs a regional two-type fuzzy neural network function, x, of the target sceneD(t) is the input of the target model at time t, wnew(t) is the back-end layer output weight parameter of the target model at time t,is the expected output of the target model at time t
wnew(t)=wold(t)+δ(t)wS(tθ) (21)
Wherein, wold(t) is the back-end layer initial output weight of the target model at time t, wS(t) is the source model back-part layer output weight at time t, δ (t) is the balance parameter at time t, 0<δ(t)<1, representing the relation between a target model and a source model;
in the interval two-type fuzzy neural network model, three variables are updated: the target model back-part layer output weight, the source model back-part layer output weight and the balance parameter are updated according to the following formula
Wherein, wS(t +1) is the source model back-end-of-layer output weight at time t +1, η1Is the learning rate of the source model back-end output weights,is the partial derivative, w, of the target function at time t with respect to the source model back-part layer output weightD(t +1) is the target model back-end output weight at time t +1, wD(t) is the target model back-end layer output weight at time t, η2Is the learning rate of the target model's back-end output weights,is the partial derivative of the target function at the time t with respect to the output weight of the target model back-part layer, δ (t +1) is the equilibrium parameter at the time t +1, η3Is the learning rate of the balance parameter,is the partial derivative of the objective function with respect to the balance parameter at time t.
6. The intelligent knowledge-based two-type fuzzy membrane fouling decision making method according to claim 1, wherein in the first step: the membrane fouling key process variables are collected by MBR sewage treatment instruments.
7. The intelligent knowledge-based two-type fuzzy membrane fouling decision making method according to claim 1, wherein in the second step: the membrane pollution process knowledge is represented by combining membrane pollution process variable historical data and decision-making knowledge of actual operation in a water plant.
8. The data and knowledge based decision method according to claim 1, characterized by the following steps: and (3) modeling the membrane pollution by adopting an interval two-type fuzzy neural network, and updating network model parameters by adopting a migration gradient descent algorithm.
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