A method and system for controlling internal and external reflux and dosing

Abstract

The present application relates to a kind of internal and external reflux and dosing control method and system, applied to AAO process wastewater treatment system, the control method includes: internal reflux control;The internal reflux control includes internal reflux feedback control, the internal reflux feedback control includes: based on the target TN value of effluent, according to the first real-time ammonia nitrogen concentration of the end of aerobic tank, determine the first target nitrate nitrogen concentration of the end of aerobic tank;According to the error of the first real-time nitrate nitrogen concentration of the end of aerobic tank and the first target nitrate nitrogen concentration, feedback control is used to determine the feedback internal reflux flow of internal reflux pipeline, and the feedback internal reflux flow is used to adjust the total flow of internal reflux pipeline, to stabilize the real-time TN value of effluent around target TN value.The method of the present application can eliminate the nitrate nitrogen concentration fluctuation of the end of aerobic tank caused by influent quality fluctuation, and then achieve the purpose of accurately controlling the real-time TN value of effluent.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewage treatment technical field, and particularly relates to an internal and external reflux and dosing control method and system. BACKGROUND

[0002] At present, due to the increasing urbanization construction, the construction of urban sewage treatment plants tends to be saturated, and the operation of the sewage treatment plants enters the efficient operation period. With the improvement of the economic level, the environmental capacity of the river and lake is under pressure, and the protection requirements of the environment are gradually improved in various places, especially the discharge requirements of the TN (Total Nitrogen) value and the TP (Total Phosphorus) value of the effluent of the sewage treatment plant are gradually strict, so as to avoid the eutrophication caused by the high TN value and TP value of the effluent. Therefore, the sewage treatment plant is faced with the increasing pressure of standard discharge, and at the same time, the enterprise also faces the development requirements of quality improvement, energy saving and consumption reduction and the like in response to the social energy saving and emission reduction target.

[0003] In the AAO (Anaerobic-Anoxic-Oxic) process of the urban sewage treatment plant, the reflux pump in the internal and external reflux control basically operates at a fixed frequency. When the flow and water quality of the influent change, the internal and external reflux cannot be dynamically adjusted following the change of the influent, which is easy to cause the fluctuation of the TN value of the effluent, and cannot achieve the precise control of the TN value of the effluent.

[0004] In addition, in order to ensure the efficient performance of the denitrification reaction in the anoxic tank, most of the sewage treatment plants will add carbon source according to the nitrate concentration in the anoxic tank to improve the denitrification effect. When the reflux pump operates at a fixed frequency, it is easy to cause the large fluctuation range of the nitrate concentration in the anoxic tank when the flow and water quality of the influent fluctuate, so that the precise control of the carbon source dosage cannot be achieved. Sometimes, the sewage treatment plant will maintain the dosage of the carbon source at a relatively large constant value, but the utilization rate of the carbon source is unstable when the flow and water quality of the influent fluctuate, which also increases the reagent cost of the sewage treatment. SUMMARY

[0005] (I) Technical problem to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides an internal and external reflux and dosing control method and system, which solves the technical problem that the TN value of the effluent cannot be precisely controlled when the flow and water quality of the influent change in the prior art.

[0007] (II) Technical scheme

[0008] In order to achieve the above-mentioned purpose, the main technical scheme adopted by the present application comprises:

[0009] In a first aspect, an embodiment of the present application provides an internal and external reflux and dosing control method applied to an AAO process wastewater treatment system. The AAO process wastewater treatment system delivers the influent to be treated to an anaerobic tank, an anoxic tank, an aerobic tank, and a secondary sedimentation tank connected in sequence for treatment, and obtains the effluent after treatment. The aerobic tank is connected to the front end of the anoxic tank through an internal reflux pipeline. The control method comprises internal reflux control.

[0010] The internal reflux control comprises internal reflux feedback control, which comprises:

[0011] The first real-time ammonia nitrogen concentration at the end of the aerobic tank is obtained, and the first target nitrate nitrogen concentration at the end of the aerobic tank is determined based on the target TN value of the effluent.

[0012] The feedback internal reflux flow of the internal reflux pipeline is determined by feedback control according to the error between the first real-time nitrate nitrogen concentration at the end of the aerobic tank and the first target nitrate nitrogen concentration. The feedback internal reflux flow is used to adjust the total internal reflux flow of the internal reflux pipeline to stabilize the real-time TN value of the effluent around the target TN value.

[0013] Optionally, the feedback internal reflux flow of the internal reflux pipeline is determined by feedback control, which comprises:

[0014] In a control cycle, the first real-time nitrate nitrogen concentration at the end of the aerobic tank at t sampling time points is obtained.

[0015] The difference between the tth first real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration is taken as the first proportional error, the sum of the difference between each first real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration is taken as the first integral error, and the difference between the difference between the t-1th and tth first real-time nitrate nitrogen concentrations and the first target nitrate nitrogen concentration is taken as the first differential error. t is a positive integer greater than 1.

[0016] The feedback internal reflux flow of the internal reflux pipeline is determined according to formula (1) based on the first proportional error, the first integral error, and the first differential error.

[0017] The formula (1) is:

[0018]

[0019] In formula (1),

[0020] Δ r represents the first proportional error;

[0021] Δ r (i) represents the difference between the ith first real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration, and i is a positive integer less than or equal to t.

[0022] Δ r (t)-Δ r (t-1) represents the first differential error, Δ r (t-1) represents the t-1th first real-time nitrate nitrogen concentration, Δ r (t) represents the tth first real-time nitrate nitrogen concentration.

[0023] K p1 , K I1 and K D1 represent the first control parameter, K p1 , the value range of K I1 is [2, 10], and the value range of K D1 is [1, 10];

[0024] Q rf represents the feedback internal reflux flow of the internal reflux pipeline.

[0025] Optionally, the internal reflux control further comprises: internal reflux feedforward control.

[0026] The internal reflux total amount of the internal reflux pipeline is adjusted according to the feedback internal reflux flow, comprising:

[0027] determining the feedforward internal reflux flow of the internal reflux pipeline based on the internal reflux feedforward control;

[0028] calculating the sum of the feedback internal reflux flow and the feedforward internal reflux flow as the internal reflux total flow of the internal reflux pipeline.

[0029] Optionally, the determining the feedforward internal reflux flow of the internal reflux pipeline based on the internal reflux feedforward control, comprises:

[0030] obtaining the real-time TN value and the inflow of the water, and determining the feedforward internal reflux flow of the internal reflux pipeline according to formula (2) based on the target TN value of the outflow;

[0031] The formula (2) is:

[0032]

[0033] In formula (2),

[0034] Q rq represents the feedforward internal reflux flow of the internal reflux pipeline;

[0035] Q J represents the inflow of the water;

[0036] N J represents the real-time TN value of the water;

[0037] N CThe target TN value of the effluent water is shown.

[0038] Optionally, an inner reflux pump is arranged on the inner reflux pipeline, and the inner reflux pump is a variable frequency pump; the adjusting the total inner reflux amount of the inner reflux pipeline according to the feedback inner reflux flow further includes:

[0039] determining an inner reflux working frequency of the inner reflux pump according to a frequency-flow fitting curve of the inner reflux pump based on the total inner reflux flow, the inner reflux working frequency being used to control the inner reflux pump to adjust the total inner reflux flow of the inner reflux pipeline;

[0040] wherein the frequency-flow fitting curve is formula (3), and the formula (3) is:

[0041] P r =k r *Q r +b r (3);

[0042] In formula (3),

[0043] P r represents the inner reflux working frequency of the inner reflux pump;

[0044] Q r represents the total inner reflux flow;

[0045] k r and b r represent first fitting parameters.

[0046] Optionally, the AAO process sewage treatment system further includes a dosing pump arranged at the beginning of the anoxic tank, and the dosing pump is used to add carbon to the anoxic tank; the dosing pump is a variable frequency pump, and the control method further includes a dosing control.

[0047] The dosing control includes:

[0048] obtaining a second real-time ammonia nitrogen concentration at the end of the anoxic tank, and determining a second target nitrate nitrogen concentration at the end of the anoxic tank based on the target TN value of the effluent water;

[0049] determining an operating frequency of the dosing pump according to an error between the second real-time nitrate nitrogen concentration at the end of the anoxic tank and the second target nitrate nitrogen concentration by using feedback control, the operating frequency of the dosing pump being used to control the amount of carbon added to the anoxic tank by the dosing pump.

[0050] Optionally, the determining the operating frequency of the dosing pump by using feedback control includes:

[0051] obtaining the second real-time nitrate nitrogen concentration at t sampling time points in a control period,

[0052] a difference between the t-1th and tth second real-time nitrate nitrogen concentration as a second differential error; wherein t is a positive integer;

[0053] determine the working frequency of the dosing pump according to formula (4) based on the second proportional error, second integral error and second differential error; the formula (4) is:

[0054]

[0055] In formula (4),

[0056] Δ N represents the second proportional error;

[0057] Δ N (i) represents a difference between the ith second real-time nitrate nitrogen concentration and the second target nitrate nitrogen concentration, i is a positive integer less than or equal to t;

[0058] Δ N (t)-Δ N (t-1) represents the second differential error, Δ N (t-1) represents a difference between the t-1th second real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration, Δ N (t) represents a difference between the tth second real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration;

[0059] K p2 , K I2 and K D2 represent the second control parameters, K p2 , the value range of K I2 is [0.5, 10], and the value range of K D2 is [5, 20];

[0060] P J represents the working frequency of the dosing pump.

[0061] Optionally, the AAO process sewage treatment system further comprises: a secondary sedimentation tank connected to the front end of the anaerobic tank through an external reflux pipeline; the end of the aerobic tank is provided with a sludge settling ratio sensor for collecting sludge settling ratio data, and the control method further comprises: external reflux control;

[0062] The external reflux control determines a feed-forward external reflux flow based on external reflux feed-forward control, determines a feedback external reflux flow based on external reflux feedback control, and takes a sum of the feed-forward external reflux flow and the feedback external reflux flow as a total external reflux flow of the external reflux pipeline; wherein,

[0063] The outer reflux feedforward control comprises:

[0064] obtaining an influent flow rate of influent and a sludge settling ratio at the end of the aerobic tank;

[0065] determining a feedforward outer reflux flow rate according to formula (5) based on the influent flow rate and the sludge settling ratio at the end of the aerobic tank;

[0066] The formula (5) is:

[0067]

[0068] In formula (5),

[0069] Q Rq represents the feedforward outer reflux flow rate;

[0070] Q J represents the influent flow rate of influent;

[0071] SV represents the sludge settling ratio at the end of the aerobic tank.

[0072] Optionally, the outer reflux feedback control comprises:

[0073] obtaining real-time sludge concentrations of the anaerobic tank at t sampling time points in a control period;

[0074] taking a difference between the tth real-time sludge concentration and a preset target sludge concentration as a third proportional error, taking a sum of differences between each real-time sludge concentration and the target sludge concentration as a third integral error, and taking a difference between a difference between the (t-1)th and the tth real-time sludge concentrations and the target sludge concentration as a third differential error; wherein t is a positive integer;

[0075] determining a feedback outer reflux flow rate of the inner reflux pipeline according to formula (6) based on the third proportional error, the third integral error and the third differential error;

[0076] The formula (6) is:

[0077]

[0078] In formula (6),

[0079] Δ R represents the third proportional error;

[0080] Δ R (i) represents a difference between the ith real-time sludge concentration and the target sludge concentration, and i is a positive integer less than or equal to t;

[0081] Δ R (t)-Δ R(t-1) represents the third differential error, Δ R (t-1) represents the difference between the t-1th real-time sludge concentration and the target sludge concentration, Δ R (t) represents the difference between the tth real-time sludge concentration and the target sludge concentration;

[0082] K p3 , K I3 and K D3 represent the third control parameter, K p3 , the value range of K I3 is [20, 50], the value range of K D3 is [10, 25], and the value range of K Rf is [2, 10];

[0083] Q Rf represents the feedback external reflux flow of the external reflux pipeline.

[0084] In a second aspect, an embodiment of the present application provides an internal and external reflux and dosing control system applied to an AAO process wastewater treatment system, wherein the AAO process wastewater treatment system delivers the water to be treated to sequentially connected anaerobic tanks, anoxic tanks, aerobic tanks and secondary sedimentation tanks for treatment to obtain treated effluent; wherein the end of the aerobic tank is connected to the front end of the anoxic tank through an internal reflux pipeline; the secondary sedimentation tank is connected to the front end of the anaerobic tank through an external reflux pipeline; and the control system comprises:

[0085] a water inflow meter for collecting the water inflow of the AAO process wastewater treatment system;

[0086] a water TN sensor for collecting the real-time TN value of the water inflow of the AAO process wastewater treatment system;

[0087] a sludge concentration sensor arranged in the middle section of the anaerobic tank for collecting the real-time sludge concentration of the anaerobic tank;

[0088] a first ammonia nitrogen concentration sensor arranged at the end of the aerobic tank for collecting the first real-time ammonia nitrogen concentration at the end of the aerobic tank;

[0089] a first nitrate nitrogen concentration sensor arranged at the end of the aerobic tank for collecting the first real-time nitrate nitrogen concentration at the end of the aerobic tank;

[0090] a second ammonia nitrogen concentration sensor arranged at the end of the anoxic tank for collecting the second real-time ammonia nitrogen concentration at the end of the anoxic tank;

[0091] a second nitrate nitrogen concentration sensor arranged at the end of the anoxic tank for collecting the second real-time nitrate nitrogen concentration at the end of the anoxic tank;

[0092] a sedimentation ratio sensor arranged at the end of the aerobic tank for collecting the sludge sedimentation ratio at the end of the aerobic tank;

[0093] A TN sensor for collecting the real-time TN value of the effluent of the AAO wastewater treatment system;

[0094] An internal reflux pump for controlling the total internal reflux flow of the internal reflux pipeline;

[0095] An external reflux pump for controlling the total external reflux flow of the external reflux pipeline;

[0096] A dosing pump arranged at the beginning of the anoxic tank for adding carbon to the anoxic tank;

[0097] A controller comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, which, when executed by the processor, implements the steps of the internal and external reflux and dosing control method of the first aspect.

[0098] (III) Beneficial Effects

[0099] The internal and external reflux and dosing control method provided in the embodiments first determines the target nitrate concentration at the end of the aerobic tank based on the target TN value of the effluent and the real-time ammonia nitrogen concentration at the end of the aerobic tank, then determines the feedback internal reflux flow of the internal reflux pipeline using feedback control according to the error between the real-time nitrate concentration at the end of the aerobic tank and the target nitrate concentration, and further adjusts the total internal reflux flow of the internal reflux pipeline according to the feedback internal reflux flow to stabilize the real-time TN value of the effluent around the target TN value. That is, the internal reflux control method provided in the embodiments takes the nitrate concentration at the end of the aerobic tank as the controlled parameter, dynamically adjusts the first target nitrate concentration according to the first real-time ammonia nitrogen concentration at the end of the aerobic tank, and adjusts the total internal reflux flow using feedback control according to the first real-time nitrate concentration at the end of the aerobic tank. When the influent flow or water quality fluctuates, the real-time nitrate concentration at the end of the aerobic tank will also fluctuate, but the internal reflux control method provided in the present application can perform feedback control according to the nitrate concentration at the end of the aerobic tank to eliminate the fluctuation of the nitrate concentration at the end of the aerobic tank caused by the fluctuation of the influent quality, and further achieve the purpose of precisely controlling the real-time TN value of the effluent. BRIEF DESCRIPTION OF DRAWINGS

[0100] Figure 1 A flowchart of the internal reflux feedback control provided in the embodiments;

[0101] Figure 2 A schematic diagram of the architecture of the AAO wastewater treatment system provided in the embodiments;

[0102] Figure 3 A flowchart of the internal reflux control provided in the embodiments;

[0103] Figure 4 A flowchart of the dosing control provided in the embodiments;

[0104] Figure 5 A schematic diagram of an external reflux control process provided in the embodiment. DETAILED DESCRIPTION

[0105] In order to better explain the present application, so as to be understood, the present application is described in detail by specific embodiments in combination with the accompanying drawings.

[0106] It should be noted that the nitrate nitrogen concentration in the embodiment of the present application refers to the concentration of nitrogen in the form of nitrate and nitrite in the water body; the ammonia nitrogen concentration in the embodiment of the present application refers to the concentration of nitrogen in the form of free ammonia or ammonium salt in the water body.

[0107] Embodiment one

[0108] The embodiment of the present application provides an internal and external reflux and dosing control method applied to an AAO process wastewater treatment system, such as shown in the figure. Figure 2 As shown in the figure, the AAO process wastewater treatment system transports the water to be treated into the anaerobic tank, the anoxic tank, the aerobic tank and the secondary sedimentation tank connected in sequence for treatment to obtain the treated effluent. The end of the aerobic tank is connected to the front end of the anoxic tank through the internal reflux pipeline, and the internal reflux pump is arranged on the internal reflux pipeline to control the total flow of the internal reflux; the end of the secondary sedimentation tank is usually provided with a sludge reflux pump station to return the sludge precipitated in the secondary sedimentation tank to the front end of the anaerobic tank through the external reflux pipeline, and the external reflux pump is arranged on the external reflux pipeline to control the total flow of the external reflux.

[0109] The control method comprises internal reflux control, external reflux control and dosing control.

[0110] The internal reflux control comprises internal reflux feedback control and internal reflux feedforward control, as shown in the figure. Figure 1 As shown in the figure, the internal reflux feedback control comprises steps A10 to A20, which are specifically as follows:

[0111] A10, obtaining the first real-time ammonia nitrogen concentration N a1 at the end of the aerobic tank, and determining the first target nitrate nitrogen concentration N sp at the end of the aerobic tank based on the target TN value of the effluent.

[0112] The target TN value of the effluent is a reference value N s provided according to the national standard or industry standard. The preset value N k is generally slightly smaller than the reference value, so that the actual TN value interval of the effluent has a higher compliance rate. Preferably, the preset value N k is 3 mg / L smaller than the reference value N s .

[0113] Based on the above-mentioned preset value N kDetermine the first target nitrate concentration N sp =N k -N a1 .

[0114] A20. Based on the first real-time nitrate concentration N at the end of the aerobic tank. b1 With the first target nitrate concentration N sp To mitigate the error, feedback control is employed to determine the feedback internal return flow rate of the internal return pipeline. This feedback internal return flow rate is used to adjust the total internal return flow rate of the internal return pipeline, thereby stabilizing the real-time TN value of the effluent near the target TN value.

[0115] In other words, the internal recirculation control method provided in this embodiment of the invention uses the nitrate nitrogen concentration at the end of the aerobic tank as the controlled parameter and the total internal recirculation flow rate as the operating parameter, and employs feedback control for feedback adjustment. When there are fluctuations in the influent flow rate or water quality, the first real-time nitrate nitrogen concentration and the first real-time ammonia nitrogen concentration at the end of the aerobic tank will also fluctuate. The internal recirculation control method provided by this invention can dynamically adjust the first target nitrate nitrogen concentration according to the fluctuation of the first real-time ammonia nitrogen concentration, and perform feedback control based on the first real-time nitrate nitrogen concentration at the end of the aerobic tank, thereby eliminating the fluctuation of nitrate nitrogen concentration at the end of the aerobic tank caused by fluctuations in influent quality and flow rate, and thus achieving the purpose of accurately controlling the real-time TN value of the effluent.

[0116] The aforementioned feedback control can specifically be P (proportional) control, PI (proportional-integral) control, PD (proportional-derivative) control, or PID (proportional-integral-derivative) control. In a specific implementation of this embodiment, in step A20, the feedback control is PID control, and the process of determining the feedback internal return flow rate of the internal return pipeline using feedback control includes sub-steps A201 to A203, as follows:

[0117] A201. Within one control cycle, obtain the first real-time nitrate concentration N at the end of the aerobic tank at t sampling times. b1 .

[0118] Specifically, the control period is greater than or equal to 1 second and less than or equal to 1 hour. Preferably, in this embodiment, the control period is set to 10 seconds and the sampling period is 1 second, that is, t = 10 seconds.

[0119] A202. The difference between the first real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration at the t-th time is taken as the first proportional error, the sum of the differences between each first real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration is taken as the first integral error, and the difference between the (t-1)-th and t-th first real-time nitrate nitrogen concentrations and the first nitrate nitrogen concentration is taken as the first differential error; where t is a positive integer greater than 1.

[0120] A203, determining the feedback internal reflux flow of the internal reflux pipeline according to formula (1) based on the first proportional error, the first integral error and the first differential error.

[0121] The formula (1) is:

[0122]

[0123] In the formula (1),

[0124] Δ r represents the first proportional error;

[0125] Δ r (i) represents the difference between the i-th first real-time nitrate concentration and the first target nitrate concentration, i is a positive integer less than or equal to t;

[0126] Δ r (t)-Δ r (t-1) represents the first differential error, Δ r (t-1) represents the t-1th first real-time nitrate concentration, Δ r (t) represents the tth first real-time nitrate concentration;

[0127] K p1 , K I1 and K D1 represent the first control parameter, K p1 , the value range of K I1 is [2, 10], and the value range of K D1 is [1, 10];

[0128] Q rf represents the feedback internal reflux flow of the internal reflux pipeline.

[0129] The feedback control method for internal reflux feedback control provided in the embodiment is based on the first proportional error, the first integral error and the first differential error of the first target nitrate concentration at the end of the aerobic tank and the first real-time nitrate concentration, and determines the internal reflux feedback flow of the internal reflux pipeline, which can ensure the control precision and control speed of the total internal reflux flow adjustment, prevent the internal reflux ratio from oscillating repeatedly, cause the internal reflux flow to change disorderly, and affect the subsequent dosing control process.

[0130] As Figure 3 shown, based on the internal reflux feedback control steps A10 to A20, in a preferred embodiment of the present embodiment, an internal reflux control process is provided, which comprises steps A00 to A30, and specifically as follows:

[0131] A00, an internal reflux feedforward control step, which determines the feedforward internal reflux flow of the internal reflux pipeline based on internal reflux feedforward control.

[0132] Specifically, the real-time TN value and the influent flow rate of the influent water are acquired, and based on the target TN value of the effluent water, the feedforward internal reflux flow rate of the internal reflux pipeline is determined according to formula (2);

[0133] The formula (2) is:

[0134]

[0135] In formula (2),

[0136] Q rq represents the feedforward internal reflux flow rate of the internal reflux pipeline;

[0137] Q J represents the influent flow rate of the influent water;

[0138] N J represents the real-time TN value of the influent water;

[0139] N C represents the target TN value of the effluent water.

[0140] It should be noted that the above formula (2) is derived based on the internal reflux ratio. The derivation process is as follows:

[0141] Based on the influent flow rate Q J , the real-time TN value N J and the target TN value of the influent water, the ideal denitrification efficiency η is determined according to formula (2a); based on the ideal denitrification efficiency η, the internal reflux ratio r is determined according to formula (2b), and then based on the internal reflux ratio r and the influent flow rate Q J , the feedforward internal reflux flow rate Q rq is determined according to formula (2c). By arranging formula (2a), (2b) and (2c), formula (2) is obtained.

[0142] The formulas (2a), (2b) and (2c) are as follows:

[0143]

[0144]

[0145]

[0146] Steps A10 and A20 are the same as the above A10 and A20 steps.

[0147] A30, comprehensive control step, according to the feedforward internal reflux flow rate determined in step A00, and the feedback internal reflux flow rate determined in steps A10 and A20, the total internal reflux flow rate of the internal reflux pipeline is adjusted.

[0148] Specifically, the inner reflux pump is a variable frequency pump, and the step A30 specifically includes:

[0149] A301、Calculate the sum of the feedback inner reflux flow and the feedforward inner reflux flow as the total inner reflux flow of the inner reflux pipeline.

[0150] A302、Based on the total inner reflux flow, determine the inner reflux operating frequency of the inner reflux pump according to the frequency-flow fitting curve of the inner reflux pump, and the inner reflux operating frequency is used to control the inner reflux pump to adjust the total inner reflux flow of the inner reflux pipeline.

[0151] Wherein, the frequency-flow fitting curve is formula (3), and the formula (3) is:

[0152] P r =k r *Q r +b r (3);

[0153] In formula (3),

[0154] P r represents the inner reflux operating frequency of the inner reflux pump;

[0155] Q r represents the total inner reflux flow;

[0156] k r and b r represent the first fitting parameter, which depends on the selection of the inner reflux pump.

[0157] Based on the above-mentioned inner reflux control, the control method provided by the embodiment performs feedforward control based on the real-time TN value of the influent and the influent flow, and the target TN value of the effluent, to determine the feedforward inner reflux flow of the inner reflux pipeline; then determines the first target nitrate nitrogen concentration according to the first real-time ammonia nitrogen concentration at the end of the aerobic tank, and performs secondary control on the operating frequency of the inner reflux pump by feedback according to the first target nitrate nitrogen concentration at the end of the aerobic tank and the first real-time nitrate nitrogen concentration, to ensure that the first real-time nitrate nitrogen concentration at the end of the aerobic tank fluctuates within the control error range of the first target nitrate nitrogen concentration, thereby realizing accurate control of the real-time TN value of the effluent.

[0158] Embodiment two

[0159] Based on the accurate control of the first real-time nitrate nitrogen concentration at the end of the aerobic tank in embodiment one, the inner reflux ratio and the total inner reflux flow are stable and controllable, which provides a relatively reliable control environment for the dosing control and the outer reflux control of the AAO wastewater treatment system. The embodiment based on the inner reflux control provided by embodiment one specifically describes the steps of the dosing control and the outer reflux control.

[0160] The embodiment provides a control method applied to an AAO process sewage treatment system, the AAO process sewage treatment system comprising a dosing pump arranged at the beginning of an anoxic tank, the dosing pump being used for adding carbon to the anoxic tank, the dosing pump being a variable frequency pump, and the control method comprising: dosing control.

[0161] As shown in the figure, the dosing control comprises: Figure 4

[0162] B10, obtaining a second real-time ammonia nitrogen concentration N a2 at the end of the anoxic tank, and determining a second target nitrate nitrogen concentration NO sp at the end of the anoxic tank based on a target TN value of effluent.

[0163] The target TN value of effluent is a reference value N s provided according to a national standard or an industry standard, and the preset value N k is generally slightly less than the reference value, so that the actual TN value interval of effluent has a higher compliance rate. Preferably, the preset value N k is 3 mg / L less than the reference value N s .

[0164] Based on the preset value N k , the second target nitrate nitrogen concentration NO sp is determined as N k -N a2 .

[0165] B20, determining the working frequency of the dosing pump by feedback control according to the error between the second real-time nitrate nitrogen concentration N b2 at the end of the anoxic tank and the second target nitrate nitrogen concentration NO sp , the working frequency of the dosing pump being used for controlling the carbon addition amount of the dosing pump to the anoxic tank.

[0166] Specifically, the feedback control of the dosing pump is PID control, and the step B20 of determining the working frequency of the dosing pump by feedback control comprises sub-steps B201 to B203, which are specifically as follows:

[0167] B201, obtaining the second real-time nitrate nitrogen concentration at t sampling time points in a control period.

[0168] B202, taking the difference between the tth second real-time nitrate nitrogen concentration and the second target nitrate nitrogen concentration as a second proportional error, taking the sum of the difference between each second real-time nitrate nitrogen concentration and the second target nitrate nitrogen concentration as a second integral error, and taking the difference between the difference between the t-1th and tth second real-time nitrate nitrogen concentrations as a second differential error; wherein t is a positive integer.

[0169] ​B203, determining the working frequency of the dosing pump according to formula (4) based on the second proportional error, the second integral error and the second differential error.

[0170] The formula (4) is:

[0171]

[0172] In formula (4),

[0173] Δ N represents the second proportional error;

[0174] Δ N (i) represents the difference between the i-th second real-time nitrate concentration and the second target nitrate concentration, i is a positive integer less than or equal to t;

[0175] Δ N (t)-Δ N (t-1) represents the second differential error, Δ N (t-1) represents the difference between the t-1-th second real-time nitrate concentration and the first target nitrate concentration, Δ N (t) represents the difference between the t-th second real-time nitrate concentration and the first target nitrate concentration;

[0176] K p2 , K I2 and K D2 represent the second control parameters, K p2 , the value range of K I2 is [10, 50], the value range of K D2 is [0.5, 10], and the value range of K J is [5, 20];

[0177] P J represents the working frequency of the dosing pump.

[0178] The feedback control method for dosing control provided in the embodiment is based on the second proportional error, the second integral error and the second differential error between the second target nitrate concentration at the end of the anoxic tank and the second real-time nitrate concentration, and determines the working frequency of the dosing pump, that is, controls the dosing amount, so as to adjust the reaction degree of the denitrification in the anoxic tank, and further adjust the nitrate concentration at the end of the anoxic tank.

[0179] The embodiment also provides an external reflux control method applied to an AAO process sewage treatment system, the AAO process sewage treatment system comprising: a sludge reflux pump station arranged at the end of a secondary sedimentation tank to return sludge precipitated from the secondary sedimentation tank to the front end of an anaerobic tank through an external reflux pipeline, an external reflux pump arranged on the external reflux pipeline to control the total flow of the external reflux, and a sludge settling ratio sensor arranged at the end of an aerobic tank to collect sludge settling ratio data, and the control method comprises: external reflux control.

[0180] As Figure 5 shown, the external reflux control comprises steps C10 to C30, specifically as follows:

[0181] C10, determining a feed-forward external reflux flow based on the external reflux feed-forward control.

[0182] Step C10 comprises sub-steps C101 and C102, specifically as follows:

[0183] C101, obtaining an influent flow of influent and a sludge settling velocity at the end of the aerobic tank.

[0184] C102, determining a feed-forward external reflux flow according to formula (5) based on the influent flow and the sludge settling velocity at the end of the aerobic tank.

[0185] The formula (5) is:

[0186]

[0187] In formula (5),

[0188] Q Rq represents the feed-forward external reflux flow;

[0189] Q J represents the influent flow of influent;

[0190] SV represents the sludge settling velocity at the end of the aerobic tank.

[0191] It should be noted that the above formula (5) is derived based on the external reflux ratio. The derivation process is as follows:

[0192] Based on the sludge settling velocity SV at the end of the aerobic tank, the external reflux ratio R is determined according to formula (5a), and based on the external reflux ratio R and the influent flow Q J of influent, the feed-forward external reflux flow Q Rq is determined according to formula (5b). By arranging formula (5a) and (5b), formula (5) is obtained.

[0193] Formula (5a) and (5b) are specifically as follows:

[0194]

[0195] Q Rq = Q J *R (5b).

[0196] C20, determining a feedback external reflux flow based on the external reflux feedback control.

[0197] Step C20 comprises sub-steps C201 to C203, specifically as follows:

[0198] C201. In a control cycle, real-time sludge concentrations of the anaerobic tank at t sampling moments are obtained.

[0199] C202. A difference between the tth real-time sludge concentration and a preset target sludge concentration is taken as a third proportional error, a sum of differences between each real-time sludge concentration and the target sludge concentration is taken as a third integral error, and a difference between a difference between the (t-1)th real-time sludge concentration and the target sludge concentration and a difference between the tth real-time sludge concentration and the target sludge concentration is taken as a third differential error; wherein t is a positive integer.

[0200] C203. Based on the third proportional error, the third integral error and the third differential error, a feedback external reflux flow of the internal reflux pipeline is determined according to formula (6).

[0201] The formula (6) is:

[0202]

[0203] In the formula (6),

[0204] Δ R represents the third proportional error;

[0205] Δ R (i) represents a difference between the ith real-time sludge concentration and the target sludge concentration, i is a positive integer less than or equal to t;

[0206] Δ R (t)-Δ R (t-1) represents the third differential error, Δ R (t-1) represents a difference between the (t-1)th real-time sludge concentration and the target sludge concentration, Δ R (t) represents a difference between the tth real-time sludge concentration and the target sludge concentration;

[0207] K p3 , K I3 and K D3 represent third control parameters, K p3 has a value range of [20, 50], K I3 has a value range of [10, 25], and K D3 has a value range of [2, 10];

[0208] Q Rf represents the feedback external reflux flow of the external reflux pipeline.

[0209] C30. Based on the feedforward external reflux flow and the feedback external reflux flow, a total internal reflux flow of the internal reflux pipeline is adjusted.

[0210] The step C30 specifically includes steps C301 and C303, and specifically as follows:

[0211] C301、calculating the sum of the feedback external reflux flow and the feedforward external reflux flow as a total external reflux flow of the external reflux pipeline.

[0212] C302、determining an external reflux operating frequency of the external reflux pump according to the total external reflux flow based on a frequency-flow fitting curve of the external reflux pump, the external reflux operating frequency being used to control the external reflux pump to adjust the total external reflux flow of the external reflux pipeline.

[0213] wherein the frequency-flow fitting curve is formula (7), the formula (7) being:

[0214] P R =k R *Q R +b R (7);

[0215] In formula (7),

[0216] P R represents the external reflux operating frequency of the external reflux pump;

[0217] Q R represents the total external reflux flow;

[0218] k R and b R represent second fitting parameters, which depend on the type selection of the external reflux pump.

[0219] Based on the above external reflux control, the control method provided by the embodiment performs feedforward control based on the influent flow of the influent and the sludge settling ratio at the end of the aerobic tank to determine the feedforward external reflux flow of the external reflux pipeline; and performs secondary control on the operating frequency of the external reflux pump by feedback according to the real-time sludge concentration and the target sludge concentration at the end of the aerobic tank, so as to realize accurate control on the sludge concentration of the effluent.

[0220] Embodiment three

[0221] The embodiment provides an internal and external reflux and dosing control system, which is applied to an AAO process wastewater treatment system. The AAO process wastewater treatment system delivers influent to be treated to sequentially connected anaerobic tanks, anoxic tanks, aerobic tanks and secondary sedimentation tanks for treatment, and obtains treated effluent. The end of the aerobic tank is connected to the front end of the anoxic tank through an internal reflux pipeline. The secondary sedimentation tank is connected to the front end of the anaerobic tank through an external reflux pipeline. The embodiment controls the internal reflux pump, the external reflux pump and the dosing pump of the AAO process wastewater treatment system based on the control method provided by the first or second embodiment.

[0222] As shown in Figure 2 , the control system comprises:

[0223] Influent flow meter, for collecting the influent flow Q of the AAO process sewage treatment system J .

[0224] Influent TN sensor, for collecting the real-time TN value N of the influent of the AAO process sewage treatment system J .

[0225] Sludge concentration sensor, arranged in the middle section of the anaerobic tank, for collecting the real-time sludge concentration SS of the anaerobic tank.

[0226] First ammonia nitrogen concentration sensor, arranged at the end of the aerobic tank, for collecting the first real-time ammonia nitrogen concentration N at the end of the aerobic tank a1 .

[0227] First nitrate nitrogen concentration sensor, arranged at the end of the aerobic tank, for collecting the first real-time nitrate nitrogen concentration N at the end of the aerobic tank b1 .

[0228] Second ammonia nitrogen concentration sensor, arranged at the end of the anoxic tank, for collecting the second real-time ammonia nitrogen concentration N at the end of the anoxic tank a2 .

[0229] Second nitrate nitrogen concentration sensor, arranged at the end of the anoxic tank, for collecting the second real-time nitrate nitrogen concentration N at the end of the anoxic tank b2 .

[0230] Settling ratio sensor, arranged at the end of the aerobic tank, for collecting the sludge settling ratio SV at the end of the aerobic tank.

[0231] Effluent TN sensor, for collecting the real-time TN value N of the effluent of the AAO process sewage treatment system T .

[0232] Internal reflux pump 1, for controlling the internal reflux total flow Q of the internal reflux pipeline r .

[0233] External reflux pump 2, for controlling the external reflux total flow Q of the external reflux pipeline R .

[0234] Dosing pump 3, arranged at the beginning of the anoxic tank, for adding carbon to the anoxic tank.

[0235] Internal reflux flow meter, for collecting the real-time internal reflux total flow of the internal reflux pipeline.

[0236] External reflux flow meter, for collecting the real-time external reflux total flow of the external reflux pipeline.

[0237] The controller is in communication connection with the influent flow meter, influent TN sensor, sludge concentration sensor, first ammonia nitrogen concentration sensor, first nitrate nitrogen concentration sensor, second ammonia nitrogen concentration sensor, second nitrate nitrogen concentration sensor, settling ratio sensor, effluent TN sensor, internal reflux pump, external reflux pump and dosing pump; the controller comprises a memory, a processor and a computer program stored on the memory and executable on the processor, and the computer program, when executed by the processor, implements the steps of the internal and external reflux and dosing control method of the first aspect.

[0238] In a specific embodiment of the present embodiment, the controller comprises a host computer 4 and a control box 5 in communication connection, the control box being in communication connection with the influent flow meter, influent TN sensor, sludge concentration sensor, first ammonia nitrogen concentration sensor, first nitrate nitrogen concentration sensor, second ammonia nitrogen concentration sensor, second nitrate nitrogen concentration sensor, settling ratio sensor, effluent TN sensor, internal reflux pump, external reflux pump and dosing pump, and uploading real-time data collected by the above sensors to the host computer and receiving control instructions issued by the host computer, and controlling the working frequency of the internal reflux pump, external reflux pump and dosing pump according to the control instructions.

[0239] Specifically, the host computer comprises a real-time data receiving module, an internal reflux control module, a dosing control module and an external reflux control module, and specifically as follows:

[0240] The real-time data receiving module is configured to receive real-time data collected by the influent flow meter, influent TN sensor, sludge concentration sensor, first ammonia nitrogen concentration sensor, first nitrate nitrogen concentration sensor, second ammonia nitrogen concentration sensor, second nitrate nitrogen concentration sensor, settling ratio sensor and effluent TN sensor.

[0241] Since the system / device described in the above embodiments of the present application is used to implement the method of the above embodiments of the present application, the specific structure and modifications of the system / device can be understood by those skilled in the art based on the method described in the above embodiments of the present application, and thus will not be described here. Any system / device used in the method of the above embodiments of the present application belongs to the scope of the present application.

[0242] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0243] The present application is described in reference to the flowchart and / or block diagram of the method, apparatus (system) and computer program product according to an embodiment of present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as a combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions.

[0244] It should be noted that the description of the application is not limited to the embodiments described above. It will be apparent to a person skilled in the art that numerous modifications and variations of the described embodiments are possible, and the general principles of the application can be applied to other embodiments and applications without departing from the scope of the application. The described embodiments are to be considered in all respects as only illustrative and not restrictive. The scope of the application is therefore indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.

[0245] Furthermore, it is noted that the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments or examples. It will also be readily understood to those skilled in the art that the order or combination of any or all combinations of the above-described embodiments and features can be used to provide further embodiments or examples. Accordingly, the application is not to be restricted based on the specific details described herein.

[0246] While the preferred embodiments of the application have been described, additional variations and modifications can be made to the embodiments without departing from the spirit and scope of the application. Therefore, it should be understood that the application is not limited by the preferred embodiments and examples described above. Rather, the scope of the application is defined by the appended claims and their equivalents.

[0247] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. An internal and external reflux and dosing control method applied to an AAO process wastewater treatment system, wherein the AAO process wastewater treatment system delivers influent to be treated to an anaerobic tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank connected in sequence for treatment, and obtains effluent after treatment; wherein, The end of the aerobic tank is connected to the front end of the anoxic tank through an internal reflux pipeline; and the control method comprises internal reflux control; The internal reflux control comprises internal reflux feedback control, and the internal reflux feedback control comprises: a first real-time ammonia nitrogen concentration at the end of the aerobic tank is obtained, and a first target nitrate nitrogen concentration at the end of the aerobic tank is determined based on a target TN value of effluent; a feedback internal reflux flow of the internal reflux pipeline is determined by feedback control according to an error between the first real-time nitrate nitrogen concentration at the end of the aerobic tank and the first target nitrate nitrogen concentration, the feedback internal reflux flow being used to adjust a total internal reflux flow of the internal reflux pipeline to stabilize the real-time TN value of the effluent around the target TN value; The feedback internal reflux flow of the internal reflux pipeline is determined by feedback control, and the method comprises: a first real-time nitrate nitrogen concentration at the end of the aerobic tank at t sampling time points in a control period is obtained; a difference between the first real-time nitrate nitrogen concentration at the tth time point and the first target nitrate nitrogen concentration is taken as a first proportional error, a sum of differences between each of the first real-time nitrate nitrogen concentrations and the first target nitrate nitrogen concentration is taken as a first integral error, and a difference between a difference between the first real-time nitrate nitrogen concentration at the t-1th time point and the first target nitrate nitrogen concentration and a difference between the first real-time nitrate nitrogen concentration at the tth time point and the first target nitrate nitrogen concentration is taken as a first differential error; wherein t is a positive integer greater than 1; a feedback internal reflux flow of the internal reflux pipeline is determined according to formula (1) based on the first proportional error, the first integral error and the first differential error; The formula (1) is: （1）； In formula (1), represents a first proportional error; represents the difference between the i-th first real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration, i is a positive integer less than or equal to t; represents a first differential error, represents a (t-1)th first real-time nitrate nitrogen concentration, represents a tth first real-time nitrate nitrogen concentration; , and denotes a first control parameter, has a value range of [10, 25], has a value range of [2, 10], has a value range of [1, 10]; represents the feedback inner return flow of the inner return line.

2. The inner reflux control method according to claim 1, characterized by, The internal reflux control further comprises internal reflux feedforward control; The total internal reflux flow of the internal reflux pipeline is adjusted according to the feedback internal reflux flow, and the method comprises: a feedforward internal reflux flow of the internal reflux pipeline is determined based on the internal reflux feedforward control; a sum of the feedback internal reflux flow and the feedforward internal reflux flow is taken as the total internal reflux flow of the internal reflux pipeline.

3. The inner reflux control method according to claim 2, wherein The feedforward internal reflux flow of the internal reflux pipeline is determined based on the internal reflux feedforward control, and the method comprises: a real-time TN value of influent and an influent flow are obtained, and a feedforward internal reflux flow of the internal reflux pipeline is determined according to formula (2) based on a target TN value of effluent; The formula (2) is: （2）； In formula (2), feed forward inner return flow representing a feed forward inner return flow of the inner return line; Qin represents the inflow rate of the inflow water; TN represents the real-time TN value of the influent; Target TN value for water is indicated.

4. The inner reflux control method according to claim 2, wherein An internal reflux pump is arranged on the internal reflux pipeline, and the internal reflux pump is a variable frequency pump; and the total internal reflux flow of the internal reflux pipeline is adjusted according to the feedback internal reflux flow, and the method further comprises: an internal reflux working frequency of the internal reflux pump is determined based on the total internal reflux flow and a frequency-flow fitting curve of the internal reflux pump, the internal reflux working frequency being used to control the internal reflux pump to adjust the total internal reflux flow of the internal reflux pipeline; The frequency-flow fitting curve is formula (3), and the formula (3) is: （3）； In formula (3), represents the inner reflux operating frequency of the inner reflux pump; Indicates the total internal recirculation flow rate; and denotes a first fitting parameter.

5. The control method according to claim 1, wherein the AAO wastewater treatment system further comprises a dosing pump arranged at the beginning of the anoxic tank, and the dosing pump is used to add carbon to the anoxic tank; characterized in that, The dosing pump is a variable frequency pump, and the control method further comprises dosing control; The dosing control comprises: a second real-time ammonia nitrogen concentration at the end of the anoxic tank is obtained, and a second target nitrate nitrogen concentration at the end of the anoxic tank is determined based on a target TN value of effluent; According to an error between the second real-time nitrate nitrogen concentration at the end of the anoxic tank and the second target nitrate nitrogen concentration, a working frequency of a dosing pump is determined by feedback control, and the working frequency of the dosing pump is used to control a carbon dosage of the dosing pump to the anoxic tank.

6. The control method according to claim 5, characterized by The determining the working frequency of the dosing pump by feedback control comprises: In a control cycle, the second real-time nitrate nitrogen concentration at t sampling time points is obtained, a difference between the tth second real-time nitrate nitrogen concentration and the second target nitrate nitrogen concentration is taken as a second proportional error, a sum of differences between each second real-time nitrate nitrogen concentration and the second target nitrate nitrogen concentration is taken as a second integral error, and a difference between a difference between the t-1th and tth second real-time nitrate nitrogen concentrations and the second target nitrate nitrogen concentration is taken as a second differential error; wherein t is a positive integer; based on the second proportional error, the second integral error and the second differential error, a working frequency of the dosing pump is determined according to formula (4); the formula (4) is: （4）； in the formula (4), represents a second proportional error; (i) represents the difference between the ith second real-time nitrate concentration and the second target nitrate concentration, i is a positive integer less than or equal to t; represents a second differential error, represents a difference between the t-1th second real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration, represents a difference between the tth second real-time nitrate nitrogen concentration and the first target nitrate nitrogen concentration; , and denotes a second control parameter, has a value range of [10, 50], has a value range of [0.5, 10], has a value range of [5, 20]; represents the operating frequency of the dosing pump.

7. The control method of claim 1, the AAO process wastewater treatment system further comprising: the secondary sedimentation tank is connected to the front end of the anaerobic tank through an external reflux pipeline; characterized in that, the end of the aerobic tank is provided with a sludge settling ratio sensor for collecting sludge settling ratio data, and the control method further comprises external reflux control; the external reflux control determines a feedforward external reflux flow based on external reflux feedforward control, determines a feedback external reflux flow based on external reflux feedback control, and takes a sum of the feedforward external reflux flow and the feedback external reflux flow as a total external reflux flow of the external reflux pipeline; wherein, the external reflux feedforward control comprises: obtaining an influent flow of influent and a sludge settling ratio at the end of the aerobic tank; based on the influent flow and the sludge settling ratio at the end of the aerobic tank, a feedforward external reflux flow is determined according to formula (5); the formula (5) is: （5）； in the formula (5), represents the feedforward outer reflux flow rate; Qin represents the flow rate of the influent water; MLSS = mixed liquor suspended solids MLVSS = mixed liquor volatile suspended solids MLSS = mixed liquor suspended solids MLVSS = mixed liquor volatile suspended solids ML 8. The control method according to claim 7, characterized by the external reflux feedback control comprises: in a control cycle, real-time sludge concentrations of the anaerobic tank at t sampling time points are obtained; a difference between the tth real-time sludge concentration and a preset target sludge concentration is taken as a third proportional error, a sum of differences between each real-time sludge concentration and the target sludge concentration is taken as a third integral error, and a difference between a difference between the t-1th and tth real-time sludge concentrations and the target sludge concentration is taken as a third differential error; wherein t is a positive integer; based on the third proportional error, the third integral error and the third differential error, a feedback external reflux flow of the internal reflux pipeline is determined according to formula (6); the formula (6) is: （6）； in the formula (6), represents a third proportional error; represents the difference between the ith real-time sludge concentration and the target sludge concentration, i being a positive integer less than or equal to t; represents a third differential error, represents a difference between the t-1th real-time sludge concentration and the target sludge concentration, represents a difference between the tth real-time sludge concentration and the target sludge concentration; , and denotes a third control parameter, has a value range of [20, 50], has a value range of [10, 25], has a value range of [2, 10]; represents the feedback outer return flow rate of the outer return line.

9. An internal and external reflux and dosing control system applied to an AAO process sewage treatment system, wherein the AAO process sewage treatment system delivers influent to be treated to an anaerobic tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank connected in sequence for treatment, and obtains effluent after treatment; wherein, the end of the aerobic tank is connected to the front end of the anoxic tank through an internal reflux pipeline; the secondary sedimentation tank is connected to the front end of the anaerobic tank through an external reflux pipeline; characterized in that, the control system comprises: an influent flow meter for collecting an influent flow of an AAO process sewage treatment system; an influent TN sensor for collecting a real-time TN value of influent of the AAO process sewage treatment system; a sludge concentration sensor arranged in a middle section of the anaerobic tank for collecting a real-time sludge concentration of the anaerobic tank; a first ammonia nitrogen concentration sensor arranged at the end of the aerobic tank for collecting a first real-time ammonia nitrogen concentration at the end of the aerobic tank; a first nitrate nitrogen concentration sensor arranged at the end of the aerobic tank for collecting a first real-time nitrate nitrogen concentration at the end of the aerobic tank; A second ammonia nitrogen concentration sensor is arranged at the end of the anoxic tank to collect a second real-time ammonia nitrogen concentration at the end of the anoxic tank. A second nitrate nitrogen concentration sensor is arranged at the end of the anoxic tank to collect a second real-time nitrate nitrogen concentration at the end of the anoxic tank. A sludge settling ratio sensor is arranged at the end of the aerobic tank to collect a sludge settling ratio at the end of the aerobic tank. An effluent TN sensor is used to collect a real-time TN value of the effluent of the AAO wastewater treatment system. An internal reflux pump is used to control the total flow of the internal reflux pipeline. An external reflux pump is used to control the total flow of the external reflux pipeline. A dosing pump is arranged at the beginning of the anoxic tank to add carbon to the anoxic tank. The controller comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the computer program is executed by the processor to implement the steps of the internal and external reflux and dosing control method according to any one of claims 1 to 8.

Images