Denitrification System and Water Treatment Control Method Based on Empirical Model Fuzzy Control

Abstract

The present application discloses a denitrification system based on experience model fuzzy control, comprising a data input mechanism, which imports the environment and water quality parameters collected by a data collection device and the set processing parameters into a control mechanism; the control mechanism imports the parameters into an analog-digital conversion mechanism, converts the analog quantity into digital quantity and provides it to a fuzzy controller, the fuzzy controller provides the converted data to an executing mechanism through a digital-analog conversion mechanism, controls the controlled object through the executing mechanism, the executing mechanism comprises the aeration control module, the internal reflux control module and the carbon source adding control module, and the controlled object comprises an anaerobic reactor, an anoxic reactor and an aerobic reactor. The present application provides a denitrification system based on experience model fuzzy control and a control method thereof, which realizes sewage treatment through the cooperation of the aeration control module, the internal reflux control module and the carbon source adding control module for the sewage plant adopting the sewage activated sludge treatment process.

Description

Technical Field

[0001] This invention relates to the field of water treatment, and in particular to a denitrification system and control method based on empirical model fuzzy control. Background Technology

[0002] In the current water treatment industry, wastewater treatment is an indispensable part of modern water resource recycling and ecological protection. Domestic wastewater treatment plants primarily rely on operators adjusting parameters such as aeration rate, reflux ratio, and reagent dosage based on on-site instrument data and past operating experience. For example, existing patent CN202110859350.3; High Ammonia Nitrogen Wastewater Denitrification System and Treatment Method; discloses: A high ammonia nitrogen wastewater denitrification system and treatment method. The high-ammonia nitrogen wastewater denitrification system includes a water supply unit, a reaction unit, and a return unit. The water supply unit includes a raw water tank, a first inlet pipe, and a second inlet pipe, both connected to the raw water tank. The reaction unit includes, in sequence, an anaerobic tank, a first anoxic tank, a first aerobic tank, a second anoxic tank, a second aerobic tank, and a sedimentation tank. The first and second inlet pipes are connected to the anaerobic tank and the first anoxic tank, respectively, to guide water from the raw water tank to these tanks. The return unit includes a first return pipe, a second return pipe, and a third return pipe. This control mode requires operators to frequently monitor the system's operating parameters, and only highly experienced operators can modify these parameters, which is detrimental to wastewater treatment plant management. Furthermore, relying on manual experience inevitably leads to delayed control, resulting in excessive energy and chemical consumption at the wastewater treatment plant.

[0003] With the continuous integration of new technologies such as artificial intelligence, big data, cloud computing, the Internet of Things, and 5G into all aspects of the water industry, smart water management has gradually become an important direction for the transformation and upgrading of the traditional water sector. Therefore, it is urgent to combine new technologies with water management practices, gradually forming a data ecosystem that uses data analysis, data diagnosis, and data-driven decision-making, and continuously exploring the in-depth application of data, models, and AI algorithms in areas such as operation scheduling, energy conservation and consumption reduction, and emergency response. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a denitrification system and its water treatment control method based on empirical model fuzzy control, which can adjust the purification control of wastewater according to actual needs.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: a denitrification system based on empirical model fuzzy control, including a data input mechanism, which imports environmental and water quality parameters collected by a data acquisition device and set treatment parameters into a control mechanism; the control mechanism inputs the imported parameters into an analog-to-digital conversion mechanism, converting analog quantities into digital quantities and providing them to a fuzzy controller; the fuzzy controller provides the converted data to an execution mechanism through a digital-to-analog conversion mechanism; the execution mechanism controls the controlled object; the execution mechanism includes an aeration control module, an internal reflux control module, and a carbon source dosing control module; the controlled object includes an anaerobic reactor, an anoxic reactor, and an aerobic reactor.

[0006] In a preferred embodiment of the present invention, the input end of the aeration control module is connected to a dissolved oxygen control module and a nitrogen control module, and the output end of the aeration control module is controlled and connected to a blower unit and an energy consumption control mechanism through an air volume and pressure control module; the output end of the aeration control module is also controlled and connected to an electric valve opening mechanism through a flow control module.

[0007] In a preferred embodiment of the present invention, the input end of the internal reflux control module acquires the sewage flow detection parameters of the sewage flow detection mechanism, and the output end of the internal reflux control module is connected to the flow regulator of the internal reflux pump through the flow control module. The flow control module also acquires the reflux flow parameters of the reflux flow detection mechanism.

[0008] In a preferred embodiment of the present invention, the input terminal of the carbon source dosing control module acquires the sewage flow detection parameters of the sewage flow detection mechanism, and the output terminal of the carbon source dosing control module is connected to the metering pump flow regulator through the flow control module. The flow control module also acquires the carbon source flow parameters of the carbon source flow detection mechanism.

[0009] In a preferred embodiment of the present invention, a water treatment control method for a denitrification system based on empirical model fuzzy control includes the following steps: input variables: feedforward - ammonia nitrogen load of influent (influent flow rate × influent concentration); feedback - ammonia nitrogen value of effluent; weight values ​​of dissolved oxygen at low, medium and high levels;

[0010] Output variables: Controlled dissolved oxygen value; when the influent ammonia nitrogen load is low and the effluent ammonia nitrogen value is low, the target dissolved oxygen value is low; when the influent ammonia nitrogen load is high and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is high; when the influent ammonia nitrogen load is medium and the effluent ammonia nitrogen value is medium, the target dissolved oxygen value is medium; when the influent ammonia nitrogen load is medium and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is high; when the influent ammonia nitrogen load is low and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is high; the computer system calculates the dissolved oxygen control value of the reaction tank according to the input variables, namely the influent ammonia nitrogen load and the effluent ammonia nitrogen value, and the fuzzy control rules, and calculates the set pressure by the system according to the fuzzy inference synthesis rules, and then drives the blower control module and valve control module to adjust the blower and valves to achieve on-demand gas supply.

[0011] In a preferred embodiment of the present invention, the aeration control module acquires the influent flow rate, influent ammonia nitrogen value N1, effluent ammonia nitrogen value N2, and various dissolved oxygen values ​​DO through the acquisition module. a DO b DO c Based on the fuzzy control method in the fuzzy controller, the target values ​​of DO1, DO2, and DO3 are obtained; the weights A1, A2, and A3 corresponding to different dissolved oxygen levels are acquired; the influent ammonia nitrogen load N-NH3=Flow×N1 is calculated; and the current DO is calculated. m1 =DO a ×A1+DO b ×A2+DO c ×A 3； Calculate the control target DO m12 =DO1×A1+DO2×A2+DO3×A3;

[0012] Based on the principle of maximum valve opening, the opening of the duct valve is adjusted first. When the valve is opened to its maximum, DO m1 Still cannot reach DO m12 This raises the target pressure P of the fan control, and through PID control, increases the DO. m1 To DO m12 P(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*de(t) / dt, P(t) = target pressure output by the controller, e(t) = deviation signal = DO m12 -DO m1 Kp = proportional coefficient, Ki = integral coefficient, Kd = differential coefficient; the air volume and pressure control module adjusts the output of different blowers according to the target pressure P of the blower to achieve on-demand air supply.

[0013] Furthermore, the fuzzy control method in the fuzzy controller includes: when the influent ammonia nitrogen load is low and the effluent ammonia nitrogen value is low, the target dissolved oxygen value is set to a low value; when the influent ammonia nitrogen load is high and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is set to a high value; when the influent ammonia nitrogen load is medium and the effluent ammonia nitrogen value is medium, the target dissolved oxygen value is set to a medium value; when the influent ammonia nitrogen load is medium and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is set to a high value; when the influent ammonia nitrogen load is low and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is set to a high value.

[0014] In a preferred embodiment of the present invention, the aerobic-to-anoxic configuration includes control permissions, a range of the number of units that can be activated, a range of internal reflux ratios, a nitrate nitrogen setting range, a nitrate nitrogen detector signal selection, and a maximum allowable nitrate nitrogen (N-NO3) value in the anoxic tank. The maximum allowable N-NO3 value for the internal reflux ratio in the aerobic-to-anoxic reaction tank is set. When the actual nitrate nitrogen in the anoxic tank exceeds the set maximum value, it indicates that the oxidizing substances refluxed are oxygen and NO. x Excessive nitrate nitrogen is detrimental to denitrification, and the system will correct the calculated internal recirculation ratio to the minimum. 出水 Less than the minimum nitrate nitrogen (N-NO3) in the pool-internal recirculation. min When set, the system executes the minimum internal reflux ratio; when the nitrate nitrogen (N-NO3) in the effluent from the reaction tank... 出水 Greater than the pool-internal recirculation-maximum nitrate nitrogen (N-NO3) max When set, the system executes the maximum internal reflux ratio; when the nitrate nitrogen (N-NO3) in the effluent from the reaction tank... 出水 When the ratio falls between these two values, the internal reflux ratio is calculated as a linear proportion.

[0015] Furthermore, the linear proportion includes: internal reflux ratio k = k min +(k max -k min )*((N-NO3) 出水 -(N-NO3) min ) / ((N-NO3) max -(N-NO3) min ), where k max =Maximum internal reflux ratio; k min =Minimum internal reflux ratio.

[0016] In a preferred embodiment of the present invention, the circulation pumps in each corridor of the biological treatment tank are optimized and controlled; the maximum allowable N-NO3 ratio in the aerobic to anoxic transition of the reaction tank is 4.

[0017] In a preferred embodiment of the present invention, the carbon source dosing control example in the carbon source dosing module is to start dosing only when two conditions are met simultaneously; the two conditions include: condition one, the minimum allowable amount of nitrate nitrogen critical value (N-NO3). 投加minThe maximum allowable dosage of nitrate nitrogen (N-NO3) is defined as the critical value. 投加max The value of the N-NO3 meter in the anoxic section; condition two, the value of the N-NO3 meter in the anoxic section is the value at the start of the dosing; the value of the nitrate nitrogen meter (N-NO3) in the anoxic section. 缺氧 If the value is less than the set value (NO3 signal used for adjustment), then dosing will not be initiated; nitrate nitrogen meter (N-NO3) in the anoxic section. 缺氧 If the value is greater than the set value, dosing will begin in (N-NO3). 缺氧 Given the set values, gradually increase the dosage according to the set growth step size and time interval (the goal is to reduce (N-NO3)). 缺氧 The value); the two parameters regarding carbon source addition are the safety value TN. safe and maximum correction value C max The safety value TN safe These are empirical parameters calculated based on historical operating data of the wastewater treatment plant, and set within the system; the safety value TN safe When the total nitrogen (TN) in the effluent is at a high level, the ratio of TN to the safe value (TN) should be considered. safe The difference is used to calculate the maximum correction value C. max C max =TN-TN safe When the total nitrogen (TN) in the effluent exceeds the safe value (TN) safe The system will set the minimum allowed NO3 value SP. min and the maximum NO3 value SP added. max Make a correction, the correction magnitude is equal to dTN = TN - TN safe If dTN>C max Then the correction magnitude is equal to C. max dTN <C max Then the correction range equals dTN; effluent TN < safety value TN safe Then restore the minimum permissible NO3 value SP. min and the maximum N-NO3 value SP added max Return to the default setting.

[0018] The beneficial effects achieved by the technical solutions disclosed in the above embodiments are as follows:

[0019] A denitrification system and its control method based on empirical model fuzzy control are disclosed. For wastewater treatment plants using activated sludge treatment technology, wastewater treatment is achieved through the cooperation of an aeration control module, an internal reflux control module, and a carbon source addition control module. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0021] Figure 1 This is a schematic diagram of the fuzzy control algorithm in an embodiment of the present invention (where the circled cross represents a logic unit, i.e., a fuzzy algorithm unit).

[0022] Figure 2 This is a schematic diagram of the precision aeration control module in an embodiment of the present invention (where the triangular arrows represent fuzzy algorithm operators).

[0023] Figure 3 This is a schematic diagram of the internal backflow control module in an embodiment of the present invention (where the triangular arrows represent fuzzy algorithm operators).

[0024] Figure 4 This is a schematic diagram of the carbon source addition module in an embodiment of the present invention (where the triangular arrows represent fuzzy algorithm operators).

[0025] Figure 5 This is an electrical control schematic diagram in an embodiment of the present invention;

[0026] Figure 6 This is a flowchart of an embodiment of the present invention;

[0027] Figure 7 This is a table showing the meanings of pipelines in a process flow diagram. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention and therefore only show the components relevant to the present invention.

[0029] It should be noted that if directional indicators (such as up, down, bottom, top, etc.) are involved in the embodiments of the present invention, these directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature. Unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances. Example 1

[0030] like Figures 1-3As shown, the denitrification system based on empirical model fuzzy control includes a data input mechanism, which imports environmental and water quality parameters collected by the data acquisition device and the set treatment parameters into the control mechanism; the control mechanism inputs the imported parameters into the analog-to-digital conversion mechanism, which converts the analog quantities into digital quantities and provides them to the fuzzy controller; the fuzzy controller provides the converted data to the execution mechanism through the digital-to-analog conversion mechanism; the execution mechanism controls the controlled object; the execution mechanism includes the aeration control module, the internal reflux control module, and the carbon source dosing control module; the controlled object includes an anaerobic reactor, an anoxic reactor, and an aerobic reactor.

[0031] The input end of the aeration control module is connected to the dissolved oxygen control module and the nitrogen control module. The output end of the aeration control module is connected to the blower unit and the energy consumption control mechanism through the air volume and pressure control module. The output end of the aeration control module is also connected to the electric valve opening mechanism through the flow control module.

[0032] The input end of the internal reflux control module acquires the sewage flow detection parameters of the sewage flow detection mechanism. The output end of the internal reflux control module is connected to the flow regulator of the internal reflux pump through the flow control module. The flow control module also acquires the reflux flow parameters of the reflux flow detection mechanism.

[0033] The input terminal of the carbon source dosing control module acquires the sewage flow detection parameters from the sewage flow detection mechanism. The output terminal of the carbon source dosing control module is connected to the metering pump flow regulator through the flow control module, and the flow control module also acquires the carbon source flow parameters from the carbon source flow detection mechanism.

[0034] Furthermore, such as Figure 6 As shown, the process structure of the denitrification system based on empirical model fuzzy control includes an inlet gate well, a coarse screen inlet pumping station connected to the inlet gate well, and two outlets from the coarse screen inlet pumping station: one outlet introduces the filtered water into the fine screen aeration grit chamber, and the other outlet discharges the filtered water through the residual sludge discharge pipeline; the fine screen aeration grit chamber introduces the water into the primary sedimentation tank and biological treatment tank for purification, and then the purified water is introduced into the secondary sedimentation tank and sludge pumping station for treatment, and then the treated water is introduced into the filter cloth filter tank, and then the treated water is introduced into the disinfection tank and reuse pumping station, and finally the treated water is discharged.

[0035] The sludge from the primary sedimentation tank and biological treatment tank is introduced into a sludge mixing tank, where it is filtered out. Then, it undergoes dewatering in a sludge dewatering room, resulting in dry sludge. Gases from the primary sedimentation tank and biological treatment tank are discharged through pipelines to a blower room. Additionally, the primary sedimentation tank and biological treatment tank are connected to a chemical dosing room for water purification. Example 2

[0036] like Figures 1-3 As shown, based on Example 1, the water treatment control method for a denitrification system based on empirical model fuzzy control includes the following steps: Input variables: feedforward - ammonia nitrogen load of the influent (influent flow rate × influent concentration); feedback - ammonia nitrogen value of the effluent; the weight value of dissolved oxygen corresponding to low, medium, and high values; Output variable: controlled dissolved oxygen value; when the ammonia nitrogen load of the influent is low and the ammonia nitrogen value of the effluent is low, the target dissolved oxygen value is low; when the ammonia nitrogen load of the influent is high and the ammonia nitrogen value of the effluent is high, the target dissolved oxygen value is high; when the ammonia nitrogen load of the influent is medium... Furthermore, when the ammonia nitrogen value of the effluent is moderate, the target dissolved oxygen value is taken as the median value; when the ammonia nitrogen load of the influent is moderate and the ammonia nitrogen value of the effluent is high, the target dissolved oxygen value is taken as high; when the ammonia nitrogen load of the influent is low and the ammonia nitrogen value of the effluent is high, the target dissolved oxygen value is taken as high. The computer system calculates the dissolved oxygen control value of the reaction tank according to the input variables, namely the ammonia nitrogen load of the influent and the ammonia nitrogen value of the effluent, as well as the fuzzy control rules, and calculates the set pressure by the system, and then drives the blower control module and valve control module to adjust the blower and valves to achieve on-demand gas supply.

[0037] The aerobic-to-anoxic configuration includes control permissions, the range of the number of units that can be activated, the range of internal reflux ratio, the nitrate nitrogen setting range, the nitrate nitrogen detector signal selection, and the maximum allowable nitrate nitrogen (N-NO3) in the anoxic tank. The maximum allowable N-NO3 value for the internal reflux ratio in the aerobic-to-anoxic reactor is set. When the actual nitrate nitrogen in the anoxic tank exceeds the set maximum value, it indicates that the oxidizing substances refluxed are oxygen and NO. x Excessive nitrate nitrogen is detrimental to denitrification, and the system will correct the calculated internal recirculation ratio to the minimum. 出水 Less than the minimum nitrate nitrogen (N-NO3) in the pool-internal recirculation. min When set, the system executes the minimum internal reflux ratio; when the nitrate nitrogen (N-NO3) in the effluent from the reaction tank... 出水 Greater than the pool-internal recirculation-maximum nitrate nitrogen (N-NO3) max When set, the system executes the maximum internal reflux ratio; when the nitrate nitrogen (N-NO3) in the effluent from the reaction tank... 出水 When the value falls between these two extremes, the internal reflux ratio is calculated using a linear proportion. Furthermore, this linear proportion includes: internal reflux ratio k = k min +(k max -k min )*((N-NO3) 出水 -(N-NO3) min ) / ((N-NO3) max -(N-NO3) min ), where k max =Maximum internal reflux ratio; k min =Minimum internal reflux ratio.

[0038] In the carbon source dosing module, the control of carbon source dosing only begins when two conditions are met simultaneously. The two conditions include: Condition 1, the minimum allowable amount of nitrate nitrogen critical value (N-NO3). 投加min The maximum allowable dosage of nitrate nitrogen (N-NO3) is defined as the critical value. 投加max The value of the N-NO3 meter in the anoxic section; condition two, the value of the N-NO3 meter in the anoxic section is the value at the start of the dosing; the value of the nitrate nitrogen meter (N-NO3) in the anoxic section. 缺氧 If the value is less than the set value (NO3 signal used for adjustment), then dosing will not be initiated; nitrate nitrogen meter (N-NO3) in the anoxic section. 缺氧 If the value is greater than the set value, dosing will begin in (N-NO3). 缺氧 Given the set values, gradually increase the dosage according to the set growth step size and time interval (the goal is to reduce (N-NO3)). 缺氧 The value); the two parameters regarding carbon source addition are the safety value TN. safe and maximum correction value C max The safety value TN safe These are empirical parameters calculated based on historical operating data of the wastewater treatment plant, and set within the system; the safety value TN safe When the total nitrogen (TN) in the effluent is at a high level, the ratio of TN to the safe value (TN) should be considered. safe The difference is used to calculate the maximum correction value C. max C max =TN-TN safe When the total nitrogen (TN) in the effluent exceeds the safe value (TN) safe The system will set the minimum allowed NO3 value SP. min and the maximum NO3 value SP added. max Make a correction, the correction magnitude is equal to dTN = TN - TN safe If dTN>C max Then the correction magnitude is equal to C. max dTN <C max Then the correction magnitude is equal to dTN;

[0039] Outflow TN < Safety value TN safe Then restore the minimum permissible NO3 value SP. min and the maximum N-NO3 value SP added max Return to the default setting. Example 3

[0040] like Figures 1-3 As shown, based on Example 1, the water treatment control method for a denitrification system based on empirical model fuzzy control includes the following steps:

[0041] The aeration control module acquires data such as influent flow rate, influent ammonia nitrogen level (N1), effluent ammonia nitrogen level (N2), and dissolved oxygen levels (DO) through the data acquisition module. a DO b DO c Based on the fuzzy control algorithm in the fuzzy controller, the target values ​​of DO1, DO2, and DO3 are obtained; the weights A1, A2, and A3 corresponding to different dissolved oxygen levels are acquired; the influent ammonia nitrogen load N-NH3=Flow×N1 is calculated; and the current DO is calculated. m1 =DO a ×A1+DO b ×A2+DO c ×A 3； Calculate the control target DO m12 =DO1×A1+DO2×A2+DO3×A3;

[0042] Based on the principle of maximum valve opening, the opening of the duct valve is adjusted first. When the valve is opened to its maximum, DO m1 Still cannot reach DO m12 This raises the target pressure P of the fan control, and through PID control, increases the DO. m1 To DO m12 P(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*de(t) / dt, P(t) = target pressure output by the controller, e(t) = deviation signal = DO m12 -DO m1 Kp = proportional coefficient, Ki = integral coefficient, Kd = differential coefficient; the air volume and pressure control module adjusts the output of different blowers according to the target pressure P of the blower to achieve on-demand air supply.

[0043] Furthermore, the fuzzy control method in the fuzzy controller includes: when the influent ammonia nitrogen load is low and the effluent ammonia nitrogen value is low, the target dissolved oxygen value is set to a low value; when the influent ammonia nitrogen load is high and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is set to a high value; when the influent ammonia nitrogen load is medium and the effluent ammonia nitrogen value is medium, the target dissolved oxygen value is set to a medium value; when the influent ammonia nitrogen load is medium and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is set to a high value; when the influent ammonia nitrogen load is low and the effluent ammonia nitrogen value is high, the target dissolved oxygen value is set to a high value.

[0044] The circulation pumps in each corridor of the biological treatment tank are optimized and controlled. The maximum allowable N-NO3 ratio for the internal recirculation ratio in the aerobic to anoxic reaction tank is 4. When the actual nitrate nitrogen in the anoxic tank exceeds the set maximum value, the oxygen and NOx in the internally recirculated oxidizing substances are excessive, which is not conducive to denitrification. The system corrects the calculated internal recirculation ratio to the minimum recirculation ratio. When the N-NO3 in the effluent of the reaction tank is less than the minimum N-NO3 setting (tank-internal recirculation-minimum N-NO3), the system executes the minimum internal recirculation ratio. When the N-NO3 in the effluent of the reaction tank is greater than the maximum N-NO3 setting (tank-internal recirculation-maximum N-NO3), the system executes the maximum internal recirculation ratio. When the N-NO3 in the effluent of the reaction tank is between the two, the internal recirculation ratio is calculated according to a linear ratio. Furthermore, the linear ratio includes: internal recirculation ratio k = k min +(k max -k min )*((N-NO3) 出水 -(N-NO3) min ) / ((N-NO3) max -(N-NO3) min ), where k max =Maximum internal reflux ratio; k min =Minimum internal recirculation ratio. More specifically, a portion of the mixed liquor flowing out of the aerobic tank needs to be recirculated back to the anoxic zone for denitrification. The mixed liquor recirculation ratio R affects the denitrification effect. According to the relationship between the denitrification rate η of the A2 / O system and the mixed liquor recirculation ratio R, η=1 / (R+r), the larger the mixed liquor recirculation ratio, the higher the denitrification rate. However, when the mixed liquor recirculation ratio is too large, the power consumption for recirculation is too high, resulting in a significant increase in operating costs. In addition, when the carbon source of the system is insufficient, increasing the internal recirculation does not improve the denitrification efficiency.

[0045] The aeration control module and the internal reflux control module work together to optimize nitrogen removal efficiency; the system is set with a minimum allowable N-NO3 dosage. min The maximum allowable amount of N-NO3 to be added is N. max The NO3 value at the end of the reaction tank is higher than that of N. min The first condition for adding the medicine has been met, and the set dosage will be N. min and N max Calculated proportionally between them, when the NO3 value at the end is greater than N. max At that time, the maximum dosage is allowed; the system is set with the target N-NO3 value N in the middle section of the biochemical tank. shc时 The N-NO3 level in the middle section of the biological treatment tank is the second condition for initiating chemical dosing; N-NO3 level in the middle section of the biological treatment tank <N shc If the chemical dosing is not initiated, then the dosing process will not be started; in the middle section of the biological treatment tank, N-NO3 > N. shc The dosage will be increased starting when N-NO3 > N. shcThe dosage is increased under certain conditions; the maximum dosage is controlled based on the NO3 value at the end of the reaction tank; the minimum liquid level in the carbon source storage tank is L. min If the liquid level falls below this level, the carbon source dosing pump will automatically stop.

[0046] Working principle:

[0047] This invention presents a denitrification system and its control method based on empirical model fuzzy control. Targeting wastewater treatment plants employing activated sludge treatment processes, the system utilizes an aeration control module, an internal recirculation control module, and a carbon source dosing control module to achieve wastewater treatment. The empirical model-based fuzzy control denitrification system uses a data acquisition module to collect flow and water quality data from the wastewater treatment plant's influent pump station, biological treatment tank, and effluent pump station, as well as relevant data from the blower units and duct regulating valves. This data is processed and analyzed by a fuzzy controller. Based on a multi-level feedback queue algorithm, the fuzzy controller adds priority fuzzy control to derive the control target parameters, which are then sent to the PLC control system. The PLC control system then transmits the operating parameters to each control device, driving the device to perform corresponding operations. Simultaneously, the system monitors changes in the effluent target value. If the control target parameter is reached, the current operating state is maintained; otherwise, the operating parameters are corrected using the difference data, and the equipment operating state is continuously adjusted until the target is achieved, forming a closed-loop control. The system can be applied to various stages from booster pumps, pretreatment, equalization tanks, biological treatment to sludge thickening, nitrification, and dewatering.

[0048] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A water treatment control method for a denitrification system based on fuzzy control of an empirical model, characterized by: The denitrification system based on the fuzzy control of the empirical model comprises: a data input mechanism, which inputs the environmental and water quality parameters collected by a data collection device and the set processing parameters into a control mechanism; the control mechanism inputs the parameters into an analog-digital conversion mechanism, converts the analog quantity into digital quantity and provides the digital quantity to a fuzzy controller, the fuzzy controller provides the converted data to an executing mechanism through a digital-analog conversion mechanism, controls the controlled object through the executing mechanism, the executing mechanism comprises an aeration control module, an internal reflux control module and a carbon source adding control module, and the controlled object comprises an anaerobic section, an anoxic section and an aerobic section of a reaction tank; the input end of the aeration control module is connected with a dissolved oxygen control module and a nitrogen control module, the output end of the aeration control module is connected with a blower set and an energy consumption control mechanism through a wind volume and pressure control module, and the output end of the aeration control module is further connected with an electric valve opening degree mechanism control through a flow control module. The water treatment control method realized by the denitrification system based on the fuzzy control of the empirical model comprises the following steps. Input variables: feed water ammonia nitrogen load (feed water flow rate*feed water concentration); feedback-out water ammonia nitrogen value; weight value of dissolved oxygen corresponding to low, medium and high; output variable: controlled dissolved oxygen value. When the feed water ammonia nitrogen load is low and the out water ammonia nitrogen value is low, the target dissolved oxygen value is low. When the feed water ammonia nitrogen load is high and the out water ammonia nitrogen value is high, the target dissolved oxygen value is high. When the feed water ammonia nitrogen load is medium and the out water ammonia nitrogen value is medium, the target dissolved oxygen value is medium. When the feed water ammonia nitrogen load is medium and the out water ammonia nitrogen value is high, the target dissolved oxygen value is high. When the feed water ammonia nitrogen load is low and the out water ammonia nitrogen value is high, the target dissolved oxygen value is high. The computer system calculates the dissolved oxygen control value of the reaction tank according to the input variables, i.e. the feed water ammonia nitrogen load and the out water ammonia nitrogen value, and the fuzzy control rule, synthesizes the rule according to the fuzzy inference, calculates the set pressure, and then drives the blower control module and the valve control module to adjust the blower and the valve, so as to realize the on-demand air supply. The aeration control module acquires the Flow influent quantity, the influent ammonia nitrogen value N1, the effluent ammonia nitrogen value N2, and each dissolved oxygen value DO through the acquisition module a , DO b , DO c ; According to the fuzzy control method in the fuzzy controller, each DO target value DO1, DO2 and DO3 is obtained; and the weights A1, A2 and A3 corresponding to the set different dissolved oxygen are obtained. The feed water ammonia nitrogen load N-NH3 is calculated as Flow*N1. Compute current DO m1 = DO a × A1 + DO b × A2 + DO c × A3; Computing control target DO m12 = DO1 x A1 + DO2 x A2 + DO3 x A3; According to the maximum opening valve principle, the air duct valve opening is adjusted preferentially, when the valve is opened to the maximum, DO m1 Still can not reach DO m12 , then raise the fan control target pressure P, and through PID control, improve DO m1 to DO m12 ; P(t) =Kp*e(t)+Ki*∫e(t)dt+Kd*de(t) / dt, P(t)=target pressure of controller output, e(t)=error signal=DO m12 -DO m1 , Kp=proportional coefficient, Ki=integral coefficient, Kd=differential coefficient; The wind volume and pressure control module adjusts the output of different blowers according to the blower target pressure P, so as to realize the on-demand air supply.

2. The water treatment control method of a denitrification system based on an empirical model fuzzy control according to claim 1, characterized by: The input end of the internal reflux control module obtains the water quality parameters collected by the data collection device, the output end of the internal reflux control module is connected with the flow regulator of the internal reflux pump through the flow control module, and the flow control module further obtains the reflux flow parameter of the reflux flow detection mechanism.

3. The water treatment control method of a denitrification system based on an empirical model fuzzy control according to claim 2, characterized by: The input end of the carbon source adding control module obtains the water quality parameters collected by the data collection device, the output end of the carbon source adding control module is connected with the flow regulator of the metering pump through the flow control module, and the flow control module further obtains the carbon source flow parameter of the carbon source flow detection mechanism.

4. The water treatment control method of a denitrification system based on an empirical model fuzzy control according to claim 3, characterized by: The configuration from the aerobic section to the anoxic section comprises: control permission, opening number range, internal reflux ratio range, nitrate nitrogen setting range, nitrate nitrogen detector signal selection, and maximum nitrate nitrogen allowed in the anoxic section; Set the internal reflux ratio of the aerobic section to the anoxic section of the reaction tank and the maximum allowed nitrate nitrogen in the anoxic section and the minimum allowed nitrate nitrogen in the anoxic section, when the actual nitrate nitrogen in the anoxic section is greater than the set maximum allowed nitrate nitrogen in the anoxic section, it indicates that the internal reflux of the oxidizing substances, i.e. oxygen and NO x Too much, not conducive to denitrification, the system will correct the calculated internal reflux ratio to the minimum reflux ratio; When the effluent nitrate nitrogen (N-NO3) of the reaction tank is 出水 When the minimum nitrate nitrogen allowed in the anoxic section is set, the system performs the minimum internal reflux ratio; When the effluent nitrate nitrogen (N-NO3) 出水 The system performs the maximum internal recycle ratio when the maximum nitrate nitrogen allowed in the anoxic section is set. When the effluent nitrate nitrogen (N-NO3) 出水 When between the minimum nitrate nitrogen allowed in the anoxic section and the maximum nitrate nitrogen allowed in the anoxic section, the internal recycle ratio is calculated in linear proportion.

5. The water treatment control method of a denitrification system based on an empirical model fuzzy control according to claim 4, characterized by: The circulating pump in each corridor in the reaction pool is controlled optimally, and the maximum internal reflux ratio of the reaction pool from the aerobic section to the anoxic section is 4.

6. The water treatment control method of a denitrification system based on an empirical model fuzzy control according to claim 5, characterized by: The control requirement of carbon source addition in the carbon source addition module is that two conditions are met at the same time to start adding the drug. The two conditions comprise: Condition 1, the critical value of the minimum amount of nitrate nitrogen (N-NO3) to be added 投加min ; the critical value of the maximum amount of nitrate nitrogen (N-NO3) to be added 投加max ; the value of When the total nitrogen TN of the effluent > the safety value TN safe , the system corrects SP min and SP max , wherein SP min is the critical value of the minimum amount of nitrate nitrogen (N-NO3) 投加min allowed to be added, SP max is the critical value of the maximum amount of nitrate nitrogen (N-NO3) 投加max allowed to be added; the correction range dTN = TN-TN safe , if dTN>C max , the correction range is equal to C max , dTN<C max , the correction range is equal to dTN; When the total nitrogen TN of the effluent < safe value TN safe , the SP is restored min and the SP max is set to the default value. Condition two, whether to start adding the drug is judged according to the parameter of the anoxic section N-NO3 instrument; anoxic section nitrate nitrogen instrument (N-NO3) 缺氧 the value of the set value, the dosing is not started; anoxic section nitrate nitrogen instrument (N-NO3) 缺氧 the value > set value, will begin to add medicine, N-NO3 缺氧 the value of the set value, according to the set growth step and time interval, gradually increase the dosage; The two parameters regarding the carbon source addition are a safety value TN safe and a maximum correction value C max where the safety value TN safe is an empirical parameter calculated from the historical operational data of the wastewater plant process and set in the system.

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