Accurate zero-delay control method for biological denitrification based on A2O sewage treatment

Abstract

The invention relates to the technical field of sewage treatment, in particular to a precise zero-delay control method for biological denitrification based on A2O sewage treatment. In the municipal sewage A2O treatment process, total Kjeldahl nitrogen concentration data at the anoxic front end and nitrate nitrogen concentration data at the anoxic tail end are obtained, and the total nitrogen concentration at the aerobic tail end is predicted in time sequence; regulating and controlling the internal reflux ratio in real time according to the real-time data of the total Kjeldahl nitrogen concentration at the front end of the oxygen deficit and the target concentration of the Kjeldahl nitrogen at the tail end Directly monitoring or calculating the concentration of anoxic front-end nitrate nitrogen according to the water inlet flow, the external reflux flow, the internal reflux flow and the aerobic tail-end nitrate nitrogen concentration of the biological tank; on the basis, the target denitrification amount is calculated in real time according to the anoxic front-end nitrate nitrogen concentration and the set anoxic tail-end nitrate nitrogen target concentration, and the adding amount of the external carbon source is calculated in real time according to the real-time target denitrification amount, so that the adding of the external carbon source is regulated and controlled in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically relates to a control method for precise zero-delay biological nitrogen removal in A 2 / O sewage treatment. Background Art

[0002] Currently, most municipal sewage treatment plants adopt the A 2 / O process, that is, an anaerobic-anoxic-aerobic biological nitrogen removal process, and achieve the purpose of biological nitrogen removal through nitrification and denitrification.

[0003] During the biological nitrogen removal process, in order to ensure that the total nitrogen in the effluent meets the discharge standard, it is necessary to monitor and regulate the process parameters at key points during the process operation. In the traditional process, the monitoring object is generally the total nitrogen in the total effluent of the sewage treatment plant, and parameters such as the carbon source dosage and the internal reflux ratio in the process are adjusted according to the concentration of the total nitrogen in the effluent. There will be a serious lag phenomenon in this regulation process. With the optimization of the process, the monitoring point is advanced, which can solve the problem of serious lag in traditional monitoring methods. For example, monitoring the nitrate nitrogen at the anoxic and aerobic ends of the biological pool, monitoring the ammonia nitrogen and nitrate nitrogen at the anoxic end, etc.; however, in the actual operation of sewage treatment plants, these methods only partially solve the problem of serious lag in regulation existing in traditional end monitoring methods to a certain extent, and cannot achieve real-time, precise process monitoring and regulation with zero delay.

[0004] Therefore, the method of the present invention obtains the nitrogen removal amount corresponding to the unit external carbon source under the current actual production conditions through the ammonia nitrogen concentration data at the front end of the anoxic zone and the nitrate nitrogen concentration data at the end of the anoxic zone, and cooperates with the derivation calculation in time sequence, and realizes zero-delay real-time regulation of the internal reflux ratio and the carbon source dosage during the operation of the biological nitrogen removal process, fundamentally eliminating the lag of the previous process parameter regulation, which has important significance for ensuring the stable operation of the production process, the stable compliance discharge of the effluent quality, and reducing the chemical agent cost, etc. Summary of the Invention

[0005] The purpose of the present invention is to provide a control method for precise zero-delay biological nitrogen removal in A 2 / O sewage treatment to solve the inevitable lag and the problem that it cannot be regulated in real time and accurately according to the actual production in the existing process regulation scheme.

[0006] To achieve the above purpose, the present invention adopts the following technical solution: A control method for precise zero-delay biological nitrogen removal in A 2 / O sewage treatment, in municipal sewage A 2In the O treatment process, obtain the total Kjeldahl nitrogen concentration data at the front end of anoxic zone, the nitrate nitrogen concentration data at the front end of anoxic zone, and the nitrate nitrogen concentration data at the end of anoxic zone; based on the real-time data of the total Kjeldahl nitrogen concentration at the front end of anoxic zone and the target concentration data of the total Kjeldahl nitrogen at the end of anoxic zone, conduct zero-delay real-time regulation on the internal reflux ratio; on the basis of the real-time regulation of the internal reflux ratio, according to the nitrate nitrogen concentration at the front end of anoxic zone and the set target concentration of nitrate nitrogen at the end of anoxic zone, calculate the target denitrification amount in real time, and from this real-time denitrification amount, calculate the dosing amount of external carbon source in real time, so as to achieve zero-delay real-time regulation of the dosing of external carbon source and realize precise biological denitrification; and through the total Kjeldahl nitrogen concentration data at the front end of anoxic zone and the nitrate nitrogen concentration data at the end of anoxic zone, accurately predict the total nitrogen in the effluent in terms of time series.

[0007] Further, at the current moment T0, the real-time value of the total Kjeldahl nitrogen concentration at the front end of anoxic zone is TKN (缺前，T0) ; set the target value of the total nitrogen concentration at the end of anoxic zone as TN 缺末目标 , and the target value of the nitrate nitrogen concentration at the end of anoxic zone as NO3 - -N 缺末目标 ; then the target value of the total Kjeldahl nitrogen concentration at the front end of anoxic zone is:

[0008]

[0009] Since:

[0010]

[0011] Thus, zero-delay real-time regulation of the internal reflux ratio can be achieved:

[0012]

[0013] In the formula, r is the internal reflux ratio; R is the external reflux ratio.

[0014] Further, in the municipal sewage A 2 O treatment process, the concentration of nitrite nitrogen in the biological system tends to be 0; if the organic nitrogen concentration at the front end of anoxic zone is stable within the range of (0, 2.0 mg / L], according to the mode or average of historical data, the total organic nitrogen concentration at the front end of anoxic zone can be set as a constant b mg / L, and at this time, the total Kjeldahl nitrogen concentration data can be calculated by monitoring the ammonia nitrogen concentration data at the front end of anoxic zone; if the organic nitrogen concentration at the front end of anoxic zone is not stable within the range of (0, 2.0 mg / L], at this time, the total Kjeldahl nitrogen concentration data can be calculated by monitoring the total nitrogen concentration data and the nitrate nitrogen concentration data at the front end of anoxic zone.

[0015] Further, on the basis of realizing real-time regulation of the internal reflux ratio, during the sewage treatment process, the influent flow rate, external reflux flow rate, internal reflux flow rate, and the tank volume of each functional area jointly determine the circulation duration of the sludge-water mixture in each functional area. Let the circulation duration of the anoxic zone be T1, and the circulation duration of the aerobic zone be T2. The total Kjeldahl nitrogen concentration at the end of the aerobic zone is set as a mg / L;

[0016] Then:

[0017]

[0018] Therefore, the concentration of nitrate nitrogen at the end of the aerobic zone can be predicted in terms of time series:

[0019]

[0020] Thus, the concentration data of nitrate nitrogen at the front end of the anoxic zone are calculated through the predicted nitrate nitrogen concentration data, influent flow rate, external reflux flow rate, and internal reflux flow rate at the end of the aerobic zone:

[0021]

[0022] Further, if the total Kjeldahl nitrogen concentration at the end of the aerobic zone is stable within the range of (0, 2.0 mg / L], based on the mode or average of historical data, a can be set as a constant, and the concentration data of nitrate nitrogen at the front end of the anoxic zone can be directly predicted; if the total Kjeldahl nitrogen concentration at the end of the aerobic zone is not stable within the range of (0, 2.0 mg / L], the nitrate nitrogen data at the end of the aerobic zone or the nitrate nitrogen data at the front end of the anoxic zone can be directly monitored.

[0023] Further, since the target of nitrate nitrogen concentration at the end of the anoxic zone is NO3 - -N 缺末目标 , setting the influent flow rate as Q, the real-time target denitrification amount § 目标 is:

[0024]

[0025] According to the real-time target denitrification amount, the real-time external carbon source dosage can be calculated.

[0026] Further, based on the fact that the sludge-water mixture reaches the end of the anoxic zone after passing through the anoxic front end for T1 time, and denitrification occurs in the anoxic zone during this period, according to the historical data of nitrate nitrogen concentration at the front end and the end of the anoxic zone, the effective denitrification amount corresponding to the unit external carbon source under the current actual production conditions can be calculated.

[0027] Further, in actual production, the denitrification amount § in the anoxic section is:

[0028]

[0029] When the carbon source dosage is X1:

[0030]

[0031] When the carbon source dosage is X2:

[0032]

[0033] The unit of the denitrification amount § is kg / h;

[0034] Where X2 - X1 = ΔX, and the change amount Δ§ of the denitrification amount corresponding to the change amount ΔX of the additional carbon source dosage is:

[0035] Δ§ = §2 - §1;

[0036] Therefore, the current actual production condition additional carbon source consumption coefficient PACC is:

[0037]

[0038] The physical meaning of PACC is: the denitrification amount corresponding to the unit additional carbon source in actual production; the unit is: Kg NO3 - -N / Kg carbon source; the physical meaning of the carbon source dosage X is: the carbon source added mass per unit time, and the unit is Kg carbon source / h.

[0039] Furthermore, based on the current additional carbon source consumption coefficient PACC, calculate the denitrification amount §0 of the current raw water carbon source as:

[0040] §0 = §1 - PACC * X1.

[0041] Furthermore, when it is necessary to remove the denitrification amount of § 目标 , the denitrification amount § 外加碳源 of the additional carbon source is:

[0042] § 外加碳源 = § 目标 - §0;

[0043] The additional carbon source added mass per unit time X 外加碳源 is:

[0044]

[0045] Therefore, according to the actual production, on the basis of making full use of the carbon source in the raw water, the accurate and real-time regulation of the additional carbon source dosage with zero delay is realized.

[0046] Advantages of the present invention:

[0047] 1. The method of the present invention requires fewer devices. When the AO 2 process operates stably, only the ammonia nitrogen concentration data at the front end of the anoxic zone and the nitrate nitrogen concentration data at the end of the anoxic zone need to be obtained, and the equipment cost is lower;

[0048] 2. The method of the present invention can achieve zero-delay real-time regulation of the reflux ratio, accurately control the total Kjeldahl nitrogen concentration in the anoxic zone to ensure the load of the aerobic section, and after adjustment, can achieve zero-delay real-time regulation of the carbon source dosage to ensure the denitrification effect in the anoxic section, thereby ensuring the stable compliance of the effluent. While achieving real-time non-lagging regulation, it ensures the stable operation of the process;

[0049] 3. The method of the present invention conforms to actual production control, uses an advanced timing algorithm to monitor the denitrification amount of raw water and the denitrification amount of the added external carbon source in real time, so as to be able to achieve more accurate carbon source dosing and regulation, achieve the accurate prediction of the total nitrogen in the effluent and the purpose of in-situ accurate biological denitrification, which is of great significance for ensuring the effluent stability, saving chemicals and reducing costs. Detailed implementation manners

[0050] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention.

[0051] In the A 2 O treatment process of municipal sewage, the municipal sewage undergoes an anaerobic-anoxic-aerobic process. Through aerobic nitrification in the aerobic section, ammonia nitrogen is oxidized to nitrate nitrogen, and through internal reflux, the nitrate nitrogen is refluxed to the anoxic section, where denitrification occurs in the anoxic section to achieve the biological denitrification process.

[0052] During the operation of the process, the internal and external reflux has a dilution effect on the influent water quality indicators. Among them, the dilution of the total Kjeldahl nitrogen in the influent can ensure the treatment load of the aerobic section; in addition, it may be necessary to add a carbon source in the anoxic section to ensure the denitrification reaction effect in the anoxic section.

[0053] In the following embodiments of the present invention, first of all, it needs to be clear that for the total nitrogen in municipal sewage treatment, it includes total nitrate nitrogen and total Kjeldahl nitrogen (TKN). Among them, total nitrate nitrogen includes nitrate nitrogen and nitrite nitrogen, and the content of nitrite nitrogen is extremely low and can be ignored; total Kjeldahl nitrogen includes ammonia nitrogen and organic nitrogen, that is, total nitrogen = nitrate nitrogen + ammonia nitrogen + organic nitrogen. Among them, nitrate nitrogen undergoes denitrification and nitrogen removal in the anoxic zone, ammonia nitrogen is oxidized to nitrate nitrogen in the aerobic zone, and organic nitrogen hardly changes in the anoxic zone and the aerobic zone.

[0054] Secondly, during the operation of the A 2 O process, the flow-through time of the mud-water mixture in the anoxic section is T1, and the flow-through time in the aerobic section is T2 (it should be noted that the flow-through time of the mud-water mixture in the anoxic section and the aerobic section is jointly determined by the influent flow rate, external reflux flow rate, internal reflux flow rate and the tank volume of each functional area and changes in real time). The influent volume flow rate of municipal sewage per unit time is Q, the internal reflux ratio is r, the external reflux ratio is R, and the tank volume is generally a fixed constant V; the current time is set as T0.

[0055] Example 1

[0056] In the actual operation of the municipal sewage A 2 In the O treatment process, it is found that the concentration of nitrite nitrogen in the biological system tends to 0 and can be ignored; the concentration of Kjeldahl nitrogen at the aerobic end is stable in the range of (0, 2.0 mg / L]; the concentration of organic nitrogen at the anoxic front end is stable in the range of (0, 2.0 mg / L].

[0057] The actual operation data related to 2023 are as follows:

[0058] Table 1 Record table of Kjeldahl nitrogen concentration in the effluent at the aerobic end

[0059]

[0060]

[0061] Table 2 Record table of organic nitrogen concentration in the influent at the anoxic front end

[0062]

[0063]

[0064] It can be clearly seen that in the municipal sewage A 2 During the stable operation of the O treatment process, it can be set that the total Kjeldahl nitrogen concentration at the aerobic end is a mg / L, and the total organic nitrogen concentration at the anoxic front end is b mg / L. a and b can take the mode or average of the historical data.

[0065] Therefore, in this example, an on-line ammonia nitrogen monitor is installed at the anoxic front end, and an on-line nitrate nitrogen monitor is installed at the anoxic end.

[0066] Then, the total nitrogen TN concentration at the anoxic front end is:

[0067]

[0068] Where:

[0069]

[0070] The total nitrogen TN concentration at the anoxic end is:

[0071]

[0072] The total nitrogen TN concentration at the aerobic end is:

[0073]

[0074] And at the aerobic end:

[0075]

[0076] The aerobic terminal nitrate nitrogen concentration can be obtained from equations (2), (4), and (5), that is:

[0077]

[0078] At A 2 During the operation of the AO process, there is:

[0079]

[0080] From equations (6) and (7), the real-time nitrate nitrogen concentration at the front end of the anoxic zone can be obtained. Thus, based on the ammonia nitrogen concentration data detected at the front end of the anoxic zone and the nitrate nitrogen concentration data detected at the end of the anoxic zone, the nitrate nitrogen concentration data at the front end of the anoxic zone can be calculated using an advanced time series algorithm.

[0081] Set the total nitrogen concentration target value at the end of the anoxic zone to TN 缺末目标 , and the nitrate nitrogen concentration target value at the end of the anoxic zone to NO3 - -N 缺末目标 ; Denote the total Kjeldahl nitrogen concentration target value at the front end of the anoxic zone as TKN 缺前目标 .

[0082] Thus, during the operation of the AO process, at time T0, the regulation of the internal reflux is as follows: 2 Since the total Kjeldahl nitrogen hardly changes in the anoxic zone, there is:

[0083] Since the total Kjeldahl nitrogen hardly changes in the anoxic zone, there is:

[0084]

[0085] Among them, both TN 缺末目标 and NO3 - -N 缺末目标 can be set as constant values according to the discharge standard, actual production experience, etc. Thus, in this process, only the internal reflux needs to be adjusted to make and TKN 缺前目标 consistent. During the process, from equation (2), we get From equation (8), we get TKN 缺前目标 , that is:

[0086]

[0087] That is also:

[0088]

[0089] Thus, in this embodiment, by measuring the ammonia nitrogen at the front end of the anoxic zone, zero-delay adjustment of the internal reflux ratio can be achieved.

[0090] At time T0, the regulation of the carbon source dosage is as follows:

[0091] The target total denitrification amount § 目标 is:

[0092]

[0093] From formula (7), that is:

[0094]

[0095] Therefore, in the method of the present invention, by measuring the concentration of ammonia nitrogen at the front end of the anoxic zone and the concentration of nitrate nitrogen at the end of the anoxic zone, using an advanced time series algorithm to calculate the total nitrogen concentration at the end of the aerobic zone at T1+T2, and after adjusting the internal reflux ratio, calculating the real-time concentration of nitrate nitrogen at the front end of the anoxic zone at T0, the target total denitrification amount § 目标 can be calculated in real time.

[0096] Therefore, according to the real-time target total denitrification amount § 目标 , the dosage of the carbon source is calculated.

[0097] In the technical solution of the present invention, by analyzing historical production data, calculating the denitrification amounts of the raw water carbon source and the externally added carbon source, the effective denitrification amount corresponding to the unit externally added carbon source, and providing the actual externally added carbon source consumption coefficient (PACC) in production, the limitations of laboratory data are completely solved.

[0098] First, the denitrification amount § in the anoxic zone is:

[0099]

[0100] Then, if the mass of the carbon source added per unit time is X1, the denitrification amount §1 at this time is:

[0101]

[0102] If the mass of the carbon source added per unit time is X2, where X2 - X1 = ΔX, the denitrification amount §2 at this time is:

[0103]

[0104] Therefore, X2 - X1 = ΔX, and the change amount Δ§ of the denitrification amount corresponding to the change amount ΔX of the externally added carbon source is:

[0105] Δ§ = §2 - §1 (16)

[0106] Therefore, the externally added carbon source consumption coefficient (denitrification amount corresponding to the unit carbon source) PACC in actual production is:

[0107] PACC = Δ§ / ΔX (17)

[0108] The unit of PACC is: Kg NO3 - -N / Kg carbon source.

[0109] Then the denitrification amount §0 of the raw water carbon source is:[[]]

[0110] §0 = §1 - PACC * X1 (18) Thus, when it is necessary to remove § 目标 of the denitrification amount, the denitrification amount § 外加碳源 of the externally added carbon source is:[[]]

[0111] § 外加碳源 = § 目标 - §0 (19) From equations (17) and (19), the mass X 外加碳源 added per unit time of the externally added carbon source can be obtained as:[[]]

[0112] X 外加碳源 = (§ 目标 - §0) / PACC (20)

[0113] Thus, in this embodiment, by real-time detecting and recording the ammonia nitrogen concentration at the front end of the anoxic zone, the nitrate nitrogen concentration at the end of the anoxic zone, the influent flow rate, the internal reflux flow rate, and the external reflux flow rate, and combining with an advanced time series algorithm, calculating the consumption coefficient of the externally added carbon source and the denitrification amount of the raw water carbon source in actual production, the internal reflux ratio and the dosing amount of the externally added carbon source can be calculated and adjusted in real time with zero delay, and accurate prediction of the total nitrogen in the effluent and in-situ accurate biological denitrification can be achieved.

[0114] Table 3 Record table of the effluent concentration data at the aerobic end in 2024 after using the method of this embodiment

[0115]

[0116] It can be seen that by adopting the method of this embodiment, the effluent at the aerobic end can stably meet the standards. In addition, before using the method of this embodiment, the annual cumulative specific consumption of the carbon source was 109 ppm. Under the condition that the influent water quality, water volume, and process did not change significantly, after using the method of this embodiment, the annual cumulative specific consumption of the carbon source was 52 ppm, and the specific consumption of the carbon source dosing decreased to 47.7%, saving 52.3% of the carbon source dosing amount.

[0117] Embodiment 2

[0118] If the Kjeldahl nitrogen concentration at the aerobic end is not within the range of (0, 2.0 mg / L] and is unstable, on the basis of Embodiment 1, Embodiment 1 can be deformed to a certain extent. That is, in this embodiment, an on-line ammonia nitrogen monitor and an on-line nitrate nitrogen monitor are installed at the front end of the anoxic zone; an on-line nitrate nitrogen monitor is installed at the end of the anoxic zone.

[0119] Similarly, according to Equation (10), zero-delay adjustment of the internal reflux ratio can also be achieved; according to Equation (20), real-time calculation and dosing of the additional carbon source dosage can be achieved without delay.

[0120] The difference between this embodiment and Embodiment 1 is that the concentration of Kjeldahl nitrogen at the aerobic end is not within the range of (0, 0.5 mg / L] and is unstable. Therefore, according to Equations (6)-(7), the nitrate nitrogen concentrations at the aerobic end and the anoxic front cannot be accurately predicted. For the nitrate nitrogen concentration at the anoxic front, it is directly monitored by an on-line nitrate nitrogen monitor at the anoxic front.

[0121] Based on the ammonia nitrogen data at the anoxic front and the organic nitrogen data b obtained from the mode or average of historical data, the total Kjeldahl nitrogen concentration at the anoxic front can be obtained, and the total nitrogen concentration of the aerobic effluent can be predicted by Equation (4).

[0122] Embodiment 3

[0123] If the concentration of Kjeldahl nitrogen at the aerobic end is not within the range of (0, 2.0 mg / L] and is unstable, on the basis of Embodiment 1, Embodiment 1 can be deformed to a certain extent. That is, in this embodiment, an on-line ammonia nitrogen monitor is installed at the anoxic front, an on-line nitrate nitrogen monitor is installed at the anoxic end, and an on-line nitrate nitrogen monitor is installed at the aerobic end.

[0124] Similarly, according to Equation (10), zero-delay adjustment of the internal reflux ratio can also be achieved; according to Equation (20), real-time calculation and dosing of the additional carbon source dosage can be achieved.

[0125] The difference between this embodiment and Embodiment 1 is that the concentration of Kjeldahl nitrogen at the aerobic end is not within the range of (0, 2.0 mg / L] and is unstable. Therefore, according to Equations (6)-(7), the nitrate nitrogen concentrations at the aerobic end and the anoxic front cannot be accurately predicted. For the calculation of the nitrate nitrogen concentration at the aerobic end, it is directly monitored by an on-line nitrate nitrogen monitor at the aerobic end, and then the nitrate nitrogen concentration at the anoxic front is calculated through the nitrate nitrogen concentration at the aerobic end.

[0126] Based on the ammonia nitrogen data at the anoxic front and the organic nitrogen data b obtained from the mode or average of historical data, the total Kjeldahl nitrogen concentration at the anoxic front can be obtained, and the total nitrogen concentration of the aerobic effluent can be predicted by Equation (4).

[0127] Embodiment 4

[0128] If the Kjeldahl nitrogen concentration at the aerobic end is not within the range of (0, 2.0 mg / L] and is unstable, and the organic nitrogen concentration at the front end of the anoxic zone is not within the range of (0, 2.0 mg / L] and is unstable, on the basis of Embodiment 1, Embodiment 1 can be deformed to a certain extent. That is, in this embodiment, an on-line total nitrogen monitor and an on-line nitrate nitrogen monitor are installed at the front end of the anoxic zone, and an on-line nitrate nitrogen monitor is installed at the end of the anoxic zone.

[0129] Similarly, the adjustment of the internal reflux ratio with zero delay can also be achieved according to Equation (10); the real-time calculation and dosing of the external carbon source dosing amount can be achieved according to Equation (20).

[0130] The difference between this embodiment and Embodiment 1 is that if the Kjeldahl nitrogen concentration at the aerobic end is not within the range of (0, 2.0 mg / L] and is unstable, and the organic nitrogen concentration at the front end of the anoxic zone is not within the range of (0, 2.0 mg / L] and is unstable, it is impossible to accurately predict the nitrate nitrogen concentration at the aerobic end and the front end of the anoxic zone, nor can the total Kjeldahl nitrogen concentration at the front end of the anoxic zone be accurately predicted; the calculation of the nitrate nitrogen concentration at the front end of the anoxic zone is directly monitored by the on-line nitrate nitrogen monitor at the front end of the anoxic zone; the data of the total Kjeldahl nitrogen concentration can be obtained from the monitoring data of the total nitrogen concentration and the nitrate nitrogen concentration at the front end of the anoxic zone, and the total nitrogen concentration of the aerobic effluent can be predicted by Equation (4).

[0131] The present invention is not limited to the above best implementation mode. Anyone can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has the same or similar technical solutions as the present application, it falls within the protection scope of the present invention.

Claims

1. A control method for precise zero-delay biological nitrogen removal in AO sewage treatment, characterized in that: 2 O sewage treatment biological denitrification precise zero-delay control method, characterized by: In municipal sewage A 2 In the O treatment process, obtain the total Kjeldahl nitrogen concentration data at the front end of anoxia, the nitrate nitrogen concentration data at the front end of anoxia, and the nitrate nitrogen concentration data at the end of anoxia; Based on the real-time data of the total Kjeldahl nitrogen concentration at the anoxic front end and the target concentration data of the total Kjeldahl nitrogen at the anoxic end, the internal reflux ratio is adjusted in real time with zero delay; on the basis of the real-time adjustment of the internal reflux ratio, according to the nitrate nitrogen concentration at the anoxic front end and the set target concentration of nitrate nitrogen at the anoxic end, the target denitrification amount is calculated in real time, and from this real-time denitrification amount, the dosage of the external carbon source is calculated in real time, realizing zero-delay real-time control of the addition of the external carbon source and achieving precise biological denitrification; and through the total Kjeldahl nitrogen concentration data at the anoxic front end and the nitrate nitrogen concentration data at the anoxic end, the total nitrogen in the effluent is accurately predicted in terms of time series.

2. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that: At the current moment T0, the real-time value of the total Kjeldahl nitrogen concentration at the front end of the anoxic section is Set the target value of the total nitrogen concentration at the end of the anoxic section as TN 缺末目标 , and the target value of the nitrate nitrogen concentration at the end of the anoxic section as NO3 - -N 缺末目标 ; then the target value of the total Kjeldahl nitrogen concentration at the front end of the anoxic section is: Since: Therefore, zero-delay real-time control of the internal reflux ratio can be achieved: In the formula, r is the internal reflux ratio; R is the external reflux ratio.

3. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that: The municipal sewage A mentioned above 2 In the O treatment process, the nitrite nitrogen concentration in the biological system tends to be 0; if the organic nitrogen concentration at the front end of the anoxic zone is stable in the range of (0, 2.0 mg / L], according to the mode or average of historical data, the total organic nitrogen concentration at the front end of the anoxic zone can be set as a constant b mg / L. At this time, the total Kjeldahl nitrogen concentration data can be calculated by monitoring the ammonia nitrogen concentration data at the front end of the anoxic zone; if the organic nitrogen concentration at the front end of the anoxic zone is not stable in the range of (0, 2.0 mg / L], the total Kjeldahl nitrogen concentration data can be calculated by monitoring the total nitrogen concentration data and nitrate nitrogen concentration data at the front end of the anoxic zone.

4. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that: On the basis of realizing the real-time control of the internal reflux ratio, in the process of sewage treatment, the influent flow rate, the external reflux flow rate, the internal reflux flow rate and the pool volume of each functional area jointly determine the flow-through time of the mixed liquid of mud and water in each functional area. Let the flow-through time of the anoxic area be T1, and the flow-through time of the aerobic area be T2. The total Kjeldahl nitrogen concentration at the end of the aerobic area is set as a mg / L; Then there is: Therefore, the concentration of nitrate nitrogen at the end of the aerobic area can be predicted in terms of time series: Thus, based on the predicted nitrate nitrogen concentration data at the end of the aerobic area, the influent flow rate, the external reflux flow rate and the internal reflux flow rate, the nitrate nitrogen concentration data at the anoxic front end are calculated:

5. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that: If the total Kjeldahl nitrogen concentration at the end of the aerobic area is stable within the range of (0, 2.0 mg / L], based on the mode or average of historical data, a can be set as a constant, and the nitrate nitrogen concentration data at the anoxic front end can be directly predicted; if the total Kjeldahl nitrogen concentration at the end of the aerobic area is not stable within the range of (0, 2.0 mg / L], the nitrate nitrogen data at the anoxic front end or the nitrate nitrogen data at the end of the aerobic area can be directly monitored and then the nitrate nitrogen data at the anoxic front end are calculated.

6. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that: Since the target of nitrate nitrogen concentration at the anoxic end is NO3 - -N 缺末目标 , assuming the influent flow rate is Q, the real-time target denitrification amount § 目标 is as follows: The real-time dosage of the external carbon source can be calculated based on the real-time target denitrification amount.

7. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that: According to the fact that the mixed liquid of mud and water reaches the anoxic end after passing through the anoxic front end for T1 time, and denitrification occurs in the anoxic area during this period, based on the historical data of the nitrate nitrogen concentration at the anoxic front end and the anoxic end, the effective denitrification amount corresponding to the unit external carbon source under the current actual production conditions can be calculated.

8. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that In actual production, the denitrification amount § in the anoxic section is: When the dosage of the carbon source is X1: When the dosage of the carbon source is X2: The unit of the denitrification amount § is kg / h; Where X2 - X1 = ΔX, and the change amount Δ§ of the denitrification amount corresponding to the change amount ΔX of the dosage of the external carbon source is: Δ§ = §2 - §1; Therefore, the external carbon source consumption coefficient PACC under the current actual production conditions is: The physical meaning of PACC is: the denitrification amount corresponding to a unit of externally added carbon source in actual production; the unit is: Kg NO3 - -N / Kg carbon source; the physical meaning of the carbon source dosage X is: the mass of carbon source added per unit time, and the unit is Kg carbon source / h.

9. A control method for precise zero-delay biological nitrogen removal in A 2 O sewage treatment, characterized in that Based on the current external carbon source consumption coefficient PACC, the denitrification amount §0 of the original water carbon source is calculated as: §0 = §1 - PACC * X1.

10. A control method for precise zero-delay biological nitrogen removal in AO sewage treatment according to claim 9, characterized in that, 2 During the operation of the biological nitrogen removal system, the following steps are performed: When it is necessary to remove the denitrification amount of § 目标 the denitrification amount of the externally added carbon source is § 外加碳源 as follows: § 外加碳源 ＝§ 目标 -§0； The mass X of the additional carbon source added per unit time 外加碳源 is as follows: Therefore, according to the actual production, on the basis of making full use of the carbon source in the raw water, zero-delay, accurate and real-time control of the dosage of the external carbon source is achieved.

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