Greenhouse gas emission control method and system for wastewater nitrification treatment

Abstract

The present application relates to sewage treatment technical field, especially to a kind of greenhouse gas emission control method and system applied to sewage nitration processing, the greenhouse gas emission control method is implemented in the aerobic treatment unit in sewage digestion treatment system, in the aerobic treatment unit, along the main stream direction of mixed liquor, front section measuring point and rear section measuring point are arranged, and respectively periodically obtain the first nitrite concentration time series at front section measuring point and the second nitrite concentration time series at rear section measuring point;Based on front section measuring point and rear section measuring point, front section oxygen supply device and rear section oxygen supply device are respectively configured, and based on the change trend of first and second nitrite concentration time series, the oxygen supply baseline of front section oxygen supply device is controlled, and the short-time oxygen reduction control window of rear section oxygen supply device is controlled;Wherein, oxygen supply baseline is the preset oxygen supply level executed by front section oxygen supply device, and short-time oxygen reduction control window is the time arrangement of oxygen supply reduction or intermittence implemented by rear section oxygen supply transposition.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method and system for controlling greenhouse gas emissions from wastewater nitrification treatment. Background Technology

[0002] Urban and industrial wastewater treatment plants commonly employ nitrification / denitrification processes to remove nitrogen, but these processes simultaneously generate nitrous oxide (N2O). N2O possesses significant greenhouse gas emission potential and ozone depletion potential, making it a key source of emissions in the wastewater treatment industry's greenhouse gas inventory. N2O generation is often associated with conditions such as the rapid accumulation of nitrite, ammonia-oxidizing bacterial stress caused by insufficient dissolved oxygen, and insufficient electron donors during the denitrification stage.

[0003] Existing control strategies mostly adopt constant or empirical dissolved oxygen settings to ensure that the effluent meets the standards, which can easily lead to high energy consumption and N2O emission peaks under disturbance conditions. There are also solutions that achieve feedback control by configuring dedicated online N2O monitoring, but the equipment is expensive, maintenance is complex, and it is susceptible to environmental conditions, making it difficult to apply in large-scale projects. Summary of the Invention

[0004] In one embodiment of the present invention, a method for controlling greenhouse gas emissions from wastewater nitrification treatment is provided, which is implemented in the aerobic treatment unit of a wastewater digestion treatment system and includes at least the following steps:

[0005] Within the aerobic treatment unit, front and rear measuring points are set along the main flow direction of the mixed liquid, and the time series of the first nitrite concentration at the front measuring point and the time series of the second nitrite concentration at the rear measuring point are periodically acquired.

[0006] Based on the front-end measuring point and the rear-end measuring point, a front-end oxygen supply device and a rear-end oxygen supply device are configured respectively. Based on the changing trends of the first nitrite concentration time series and the second nitrite concentration time series, the oxygen supply line of the front-end oxygen supply device is controlled, and the short-term oxygen reduction control window of the rear-end oxygen supply device is controlled.

[0007] The oxygen supply line is the preset oxygen supply level executed by the front-end oxygen supply device, and the short-term oxygen reduction control window is the time arrangement for the subsequent oxygen supply to be reduced or intermittently implemented.

[0008] In a further embodiment, the aerobic treatment unit is divided into a pre-micro-oxygen zone and a post-hypo-oxygen zone along the main flow direction of the mixture, wherein the oxygen supply target of the post-hypo-oxygen zone is lower than that of the pre-micro-oxygen zone.

[0009] The front-end micro-oxygen zone is equipped with the front-end measuring point and the front-end oxygen supply device, and is supplied with oxygen by the front-end oxygen supply device. Its oxygen supply target is to ensure that the initial nitrification is not restricted. The rear-end low-oxygen zone is equipped with the rear-end measuring point and the rear-end oxygen supply device, and is supplied with oxygen by the rear-end oxygen supply device. Its oxygen supply target is to limit the transient accumulation of intermediate nitrogen oxides.

[0010] In a further embodiment, the changing trend of the first nitrite concentration time series or the second nitrite concentration time series controls the oxygen supply line of the front-end oxygen supply device and controls the short-term oxygen reduction control window of the rear-end oxygen supply device, including the following rules:

[0011] At the beginning of a control cycle, the trend of nitrite concentration over time is evaluated based on the difference between at least two consecutive nitrite concentration sampling values ​​in the nitrite concentration time series of the previous control cycle. This trend is used to control the oxygen supply line of the oxygen supply device or the short-term oxygen reduction control window in the current control cycle.

[0012] The trend of change is at least one of the following: rising, falling, or stable.

[0013] In a further embodiment, the trend of nitrite concentration time series is evaluated based on the difference between at least two consecutive nitrite concentration sampling values ​​in the previous control period, and is determined by the following rules:

[0014] The trend is considered stable if the cumulative residence time of the nitrite concentration time series within a steady-state band is not less than a preset duration; otherwise...

[0015] When the cumulative residence time of the nitrite concentration time series within the steady-state band is less than the preset duration, then if the proportion of sample pairs with a positive difference between two adjacent nitrite concentration samples is not less than a preset proportion, the trend is determined to be upward; otherwise...

[0016] When the proportion of sample pairs with a positive difference between two adjacent nitrite concentration samples is less than a preset proportion, the trend is determined to be downward.

[0017] In a further embodiment, within any control cycle, the short-term oxygen reduction control window of the front-end oxygen supply device and / or the rear-end oxygen supply device is controlled by the following rules:

[0018] If the trend of the second nitrite concentration time series in the previous control period is upward, then the short-term oxygen reduction control window of the downstream oxygen supply device will be opened or extended in the current control period, and the oxygen supply line of the upstream oxygen supply device will be maintained in the current control period.

[0019] If the trend of the second nitrite concentration time series in the previous control period was decreasing or stable, then if the trend of the first nitrite concentration time series in the previous control period was increasing, the short-term oxygen reduction control window of the downstream oxygen supply device will be terminated in the current control period, and the oxygen supply line of the upstream oxygen supply device will be raised in the current control period; otherwise...

[0020] When the trend of the first nitrite concentration time series in the previous control cycle is decreasing or stable, the short-term oxygen reduction control window of the downstream oxygen supply device is terminated in the current control cycle, and the oxygen supply line of the upstream oxygen supply device is maintained in the current control cycle.

[0021] In a further embodiment, the anoxic treatment unit implemented in the wastewater digestion treatment system also includes at least the following steps:

[0022] An equivalent electron donor dosing device is set at the downstream boundary of the anoxic treatment unit along the mainstream direction of the mixed liquid. During the current control cycle, based on the time series change trend of the total nitrogen margin and the second nitrite concentration in the effluent of the wastewater digestion treatment system during the previous control cycle, the equivalent electron donor dosing device is controlled to add an equivalent electron donor.

[0023] In a further embodiment, the equivalent electron donor is controlled by the equivalent electron donor addition device based on the time series variation trend of the total nitrogen margin and the second nitrite concentration in the effluent of the wastewater digestion treatment system during the previous control cycle, and controlled by the following rules:

[0024] At the start of a control cycle, if the total nitrogen margin in the effluent during the previous control cycle is not less than a preset margin, and the second nitrite concentration time series is determined to be rising or stable, then the equivalent electron donor is added by the equivalent electron donor addition device in the current control cycle.

[0025] In a further embodiment, the equivalent electron donor is a substance that provides a reducing equivalent to nitrate and / or nitrite during denitrification.

[0026] In a further embodiment, the equivalent electron donor delivery device delivers the equivalent electron donor via pulsed delivery.

[0027] In a further embodiment, a greenhouse gas emission control system for wastewater nitrification treatment is also provided, comprising a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the device performs the greenhouse gas emission control method for wastewater nitrification treatment as described in any of the above embodiments.

[0028] The greenhouse gas emission control method and system for wastewater nitrification treatment provided by this invention have gains including at least:

[0029] This invention establishes a synergistic strategy of "maintaining nitrification in the front and reducing oxygen in the back" by setting up monitoring points at the beginning and end of the aerobic treatment unit, distinguishing between the micro-oxygen zone in the front and the hypo-oxygen zone in the back, and using the time series determination result of nitrite concentration from the previous control cycle to drive the oxygen supply command for the current cycle. This strategy can effectively suppress the transient accumulation of intermediate nitrogen oxides without sacrificing initial nitrification, reduce the generation and release of greenhouse gases such as nitrous oxide, and improve the system's emission reduction efficiency and process safety boundary from a mechanistic perspective.

[0030] This invention reduces unnecessary high dissolved oxygen maintenance and over-aeration by opening or extending the short-term deoxygenation control window only during the later stages of rising or plateauing oxygen levels. This improves oxygen transfer utilization and reduces blower energy consumption. Simultaneously, at the anoxic end, a small-dose equivalent electron donor pulse is added at a fixed point only when the total nitrogen in the effluent has a margin of safety. This replaces continuous carbon addition throughout the entire pool, avoiding ineffective consumption and side reactions caused by carbon sources flowing into the aerobic stage. This achieves dual optimization of energy and chemical consumption. Attached Figure Description

[0031] From the following description of embodiments in conjunction with the accompanying drawings, aspects, features, and advantages of the present invention will become clearer and more readily understood, in which:

[0032] Figure 1 This invention illustrates a first component framework of a wastewater digestion treatment system provided in one embodiment of the present invention;

[0033] Figure 2 This invention illustrates a second component framework of a wastewater digestion treatment system provided in one embodiment of the invention;

[0034] Figure 3 The present invention illustrates a method flow for controlling greenhouse gas emissions from wastewater nitrification treatment, according to an embodiment of the present invention.

[0035] Figure 4 The present invention illustrates a process for determining three trends in the time series of nitrite concentration provided by an embodiment of the present invention.

[0036] Figure 5 This invention illustrates a control process for a front / back oxygen supply device based on three changing trends and the total nitrogen margin in the effluent, according to an embodiment of the present invention.

[0037] Figure 6 The third component framework of a wastewater digestion treatment system provided in one embodiment of the present invention is shown. Detailed Implementation

[0038] To facilitate understanding of the present invention by those skilled in the art, several embodiments are now described in detail with reference to the accompanying drawings. It should be understood that the embodiments are for illustrative purposes only and not for limiting the scope of protection of the present invention; the scope of protection of the present invention is defined by the claims, and includes equivalent schemes and equivalent transformations of the claims.

[0039] In one embodiment of the present invention, the greenhouse gas emission control method for wastewater nitrification treatment proposed in the present invention is applied to, for example... Figure 1 The aerobic treatment unit in the wastewater digestion treatment system shown is an example.

[0040] Furthermore, within the aerobic treatment unit, front-end measuring points and rear-end measuring points are set along the main flow direction of the mixed liquid, and front-end oxygen supply devices and rear-end oxygen supply devices are respectively configured based on the front-end measuring points and the rear-end measuring points.

[0041] like Figure 2 As shown, the aerobic treatment unit is divided into a front micro-oxygen zone and a rear hypo-oxygen zone along the main flow direction of the mixture, wherein the oxygen supply target of the rear hypo-oxygen zone is lower than that of the front micro-oxygen zone.

[0042] It should be noted that the oxygen supply target mentioned in this embodiment refers to the reference amount of oxygen supply intensity and oxygen supply method set in the front micro-oxygen zone or the rear low-oxygen zone, which is used to constrain the dissolved oxygen supply and oxygen transfer level in the zone during the operation cycle.

[0043] Furthermore, the front-end micro-oxygen zone is equipped with the front-end measuring point and the front-end oxygen supply device, and the front-end micro-oxygen zone is supplied with oxygen by the front-end oxygen supply device, the oxygen supply target being to ensure that the initial nitrification is not restricted.

[0044] It should be noted that the "unrestricted initial nitrification" mentioned in this embodiment means that the oxygen supply capacity in the upstream micro-aerobic zone is sufficient relative to the ammonia nitrogen oxidation load in that zone, so that the ammonia oxidation reaction can be started as expected and continue without being inhibited by insufficient dissolved oxygen or oxygen transfer.

[0045] Furthermore, the downstream low-oxygen zone is equipped with the downstream measuring point and the downstream oxygen supply device, and the downstream low-oxygen zone is supplied with oxygen by the downstream oxygen supply device, the oxygen supply target of which is to limit the transient accumulation of intermediate nitrogen oxides.

[0046] It should be noted that the transient accumulation of intermediate nitrogen oxides mentioned in this embodiment refers to the abnormal increase in intermediate forms (especially nitrite and / or nitrous oxide) in the nitrification / denitrification process relative to their steady-state level in a short period of time due to the mismatch between oxygen supply and load, reaction phase or mass transfer conditions during the operation of the aerobic treatment unit, and the formation of detectable transient retention in the subsequent low-oxygen zone or downstream.

[0047] Furthermore, in this embodiment, as Figure 3 The greenhouse gas emission control method shown for wastewater nitrification treatment controls greenhouse gas emissions through at least the following steps:

[0048] S01. Periodically acquire the time series of the first nitrite concentration at the front measuring point and the time series of the second nitrite concentration at the rear measuring point.

[0049] In this embodiment, the nitrite concentration of both the front and rear measuring points is automatically collected at fixed time intervals and the timestamp is recorded synchronously, thereby forming continuous (or equally spaced) time series data.

[0050] S02a. Based on the changing trends of the first nitrite concentration time series and the second nitrite concentration time series, control the oxygen supply line of the front-end oxygen supply device and control the short-term oxygen reduction control window of the rear-end oxygen supply device.

[0051] Furthermore, the oxygen supply line mentioned in this embodiment is the preset oxygen supply level (i.e., normal oxygen supply level) executed by the front-end oxygen supply device, which serves as the reference lower limit for oxygen supply within the current control cycle, and is used to ensure that the above-mentioned initial nitrification is not restricted.

[0052] Furthermore, the short-term oxygen reduction control window described in this embodiment is the time arrangement for the oxygen supply reduction or intermittent implementation of the subsequent oxygen supply transition. It can be characterized by parameters such as controlled start offset (the start time relative to the start of this cycle), controlled cumulative duration (the total duration of one or more oxygen reduction / intermittent sub-segments in this cycle) and / or controlled duty / pulse sequence, and can be a single continuous sub-segment or the accumulation of multiple discrete sub-segments.

[0053] It should be noted that the setting of the short-term oxygen reduction control window only takes effect at the beginning of the control cycle and remains unchanged during the cycle; compared with the previous control cycle, if the cumulative controlled duration of this cycle changes from zero to non-zero, it is recorded as enabled; if it increases on the original basis, it is recorded as extended; if it is set to zero, it is recorded as terminated; the specific parameters can be fixed or adaptively determined based on the running history and online data, and are not limited by specific values.

[0054] In this embodiment, step S02, which involves controlling the oxygen supply line of the front-end oxygen supply device and controlling the short-term oxygen reduction control window of the rear-end oxygen supply device based on the changing trends of the first or second nitrite concentration time series, specifically at the beginning of each control cycle, controls the oxygen supply line or short-term oxygen reduction control window of the oxygen supply device in the current control cycle based on the three changing trends of rising, falling, and stabilizing of the two nitrite concentration time series in the previous control cycle.

[0055] In one specific embodiment, the three trends of any nitrite concentration time series are analyzed as follows: Figure 4 The determination is made based on the process shown:

[0056] The trend is considered stable if the cumulative residence time of the nitrite concentration time series within a steady-state band is not less than a preset duration; otherwise...

[0057] When the cumulative residence time of the nitrite concentration time series within the steady-state band is less than the preset duration, then if the proportion of sample pairs with a positive difference between two adjacent nitrite concentration samples is not less than a preset proportion, the trend is determined to be upward; otherwise...

[0058] When the proportion of sample pairs with a positive difference between two adjacent nitrite concentration samples is less than a preset proportion, the trend is determined to be downward.

[0059] Furthermore, the steady-state band proposed in this embodiment refers to the allowable fluctuation range used to determine whether a time series is in a stable state. Its upper and lower boundaries are pre-configured or adaptively determined by the controller based on the instrument resolution and noise level, historical fluctuation characteristics, and process objectives.

[0060] Specifically, the bandwidth proposed in this embodiment can be a fixed bandwidth or a bandwidth that is automatically adjusted during operation; when any nitrite concentration sampling value falls into this range, it is considered to be in a steady state, and its residence time is accumulated accordingly to determine whether it is stable / rising / falling. The steady state band is only used as a judgment threshold and does not limit the specific numerical range.

[0061] It should be noted that any preset value (such as preset duration or preset ratio) proposed in this embodiment is used as a reference threshold parameter for trend judgment or control execution. Its specific value can be adaptively determined through experimental calibration or historical operating data based on factors such as system scale, inlet and outlet water load, water temperature, sensor response characteristics, and control accuracy requirements. It can be a fixed setting value or dynamically adjusted within an allowable range to ensure the stability and sensitivity balance of the judgment process. The preset value is not limited to a specific value or ratio. Without affecting the technical effect, its setting method, adjustment algorithm, and corresponding range are all considered as equivalent implementation methods.

[0062] In yet another specific embodiment, based on the above three trends, within any control cycle, the short-term oxygen reduction control window of the upstream oxygen supply device and / or the downstream oxygen supply device is determined by the following... Figure 5 The rules shown are for control:

[0063] If the trend of the second nitrite concentration time series in the previous control period is upward, then the short-term oxygen reduction control window of the downstream oxygen supply device will be opened or extended in the current control period, and the oxygen supply line of the upstream oxygen supply device will be maintained in the current control period.

[0064] If the trend of the second nitrite concentration time series in the previous control period was decreasing or stable, then

[0065] If the trend of the first nitrite concentration time series in the previous control cycle is upward, the short-term oxygen reduction control window of the downstream oxygen supply device will be terminated in the current control cycle, and the oxygen supply line of the upstream oxygen supply device will be increased in the current control cycle; otherwise...

[0066] When the trend of the first nitrite concentration time series in the previous control cycle is decreasing or stable, the short-term oxygen reduction control window of the downstream oxygen supply device is terminated in the current control cycle, and the oxygen supply line of the upstream oxygen supply device is maintained in the current control cycle.

[0067] In yet another embodiment of the present invention, the greenhouse gas emission control method for wastewater nitrification treatment proposed in the present invention is applied to, for example... Figure 6 The wastewater digestion treatment system shown includes an aerobic treatment unit and an anoxic treatment unit.

[0068] like Figure 6 As shown, the anoxic treatment unit is located upstream of the aerobic treatment unit, and an equivalent electron donor dosing device is provided at the downstream boundary within the anoxic treatment unit.

[0069] It should be noted that traditional nitrification / denitrification processes usually involve aerobic treatment (nitrification) followed by anoxic treatment (denitrification).

[0070] In this embodiment, the mixed liquid flows into the aforementioned anoxic treatment unit before the aerobic treatment unit, so as to introduce the accumulation of nitrite in the later stage after the reducing material is added in advance, and avoid excessive accumulation of nitrite in the subsequent aerobic treatment unit, thereby reducing greenhouse gas emissions.

[0071] It should also be noted that, based on the aerobic treatment unit in this design, an anoxic treatment unit from a conventional design is also connected to achieve the denitrification process.

[0072] Specifically, the equivalent electron donor addition device of the present invention is set at the downstream boundary of the anoxic treatment unit or at its vicinity to add the equivalent electron donor to the mixture at a fixed point and in a certain manner.

[0073] Furthermore, the added equivalent electron donor refers to the substance that provides a reducing equivalent to nitrate and / or nitrite during denitrification, including but not limited to: added organic carbon (such as methanol, ethanol, acetic acid and its salts, mixtures of volatile fatty acids, glycerol, and COD-rich industrial by-products) and non-organic carbon or mixed donors (such as hydrogen, formic acid / formate salts, sulfur-based reducing agents, iron-based reducing agents, and endogenous fermentation broth). These substances can be used alone or in combination, and the specific selection is not limited to any particular variety.

[0074] Furthermore, in some specific embodiments, the equivalent electron donor delivery device delivers the equivalent electron donor in a pulsed, fixed-point manner. That is, at the beginning of each control cycle, the equivalent electron donor delivery device starts and stops the metering pump and the injection valve at preset times within the current control cycle, delivering the equivalent electron donor in one or more small doses at fixed points to the downstream boundary of the hypoxia treatment unit. The delivery automatically stops when the upper limit of the total delivery amount in a single control cycle is reached or the cumulative time is exhausted, and the instructions are not changed within the current control cycle.

[0075] Furthermore, in this embodiment, as Figure 3 The greenhouse gas emission control method shown for wastewater nitrification treatment also controls greenhouse gas emissions through the following steps:

[0076] S02b. During the current control cycle, based on the time series variation trends of the total nitrogen margin and the second nitrite concentration in the effluent of the wastewater digestion treatment system during the previous control cycle, the equivalent electron donor dosing device is controlled to add an equivalent electron donor.

[0077] Furthermore, the equivalent electron donor dosing device is controlled by the following rule: at the beginning of a control cycle, if the total nitrogen margin of the effluent in the previous control cycle is not lower than a preset margin, and the second nitrite concentration time series is determined to be rising or stable, then the equivalent electron donor dosing device is controlled to add an equivalent electron donor in the current control cycle.

[0078] In this embodiment, the proposed total nitrogen margin is used to determine whether the compliance margin for the current period's equivalent electron donor pulse injection is allowed. It is the non-negative difference between the target value of total nitrogen in the effluent and the estimated value of total nitrogen in the effluent based on the previous control cycle.

[0079] Furthermore, the estimated total nitrogen value in the effluent can be derived from data processed by an online total nitrogen analyzer after anomaly removal and rolling statistical processing, or it can be a value obtained through other effective methods; the target value of total nitrogen in the effluent can be a fixed setting or adaptively adjusted based on historical stability and autonomous compliance strategies, and a safety belt / buffer zone can be introduced to resist measurement errors and short-term fluctuations.

[0080] In another embodiment of the present invention, a greenhouse gas emission control system for wastewater nitrification treatment is provided, comprising a processor and a memory; the memory stores a computer program (or control logic / instruction set) executed by the processor.

[0081] When the computer program is executed by the processor, it can call the sensing and execution interface connected to the aerobic treatment unit and (and the anoxic treatment unit) to complete the greenhouse gas emission control method process for wastewater nitrification treatment provided in any of the above embodiments: periodically collect and preprocess the nitrite concentration at the front / back measuring points, determine the trend of change based on the data of the previous control cycle, issue control commands to the oxygen supply line of the front oxygen supply device and the short-term oxygen reduction control window of the back oxygen supply device in the current control cycle, and implement fixed-point pulse dosing of the equivalent electronic donor dosing device when the total nitrogen margin condition of the effluent is met; the control commands remain unchanged within the cycle and are constrained by interlocking and abnormal strategies.

[0082] It should be noted that the computer program can be implemented in the form of software, firmware or a combination thereof, and the operating environment can be a PLC, industrial computer, embedded controller or equivalent programmable platform; the program and data can be stored in a non-transitory computer-readable storage medium (such as flash memory, EEPROM, disk or solid-state drive).

[0083] It should also be noted that the specific hardware configuration and network topology of the system are not limited to a specific form. As long as the functional steps corresponding to the greenhouse gas emission control method applied to wastewater nitrification treatment can be realized, they are all within the protection scope of this invention.

[0084] In the above embodiments, the descriptions of different embodiments each have their own emphasis; technical features not detailed or described in a certain embodiment can be understood and implemented by referring to the corresponding descriptions in other embodiments. Unless otherwise expressly stated to the contrary, the technical features in each embodiment can be substituted for each other or freely combined to form new implementation methods without technical conflict. The above embodiments are only preferred / exemplary implementations of the present invention and do not constitute a limitation of the present invention.

Claims

1. A method for controlling greenhouse gas emissions from wastewater nitrification treatment, characterized in that, An aerobic treatment unit implemented in a wastewater nitrification system includes at least the following steps: Within the aerobic treatment unit, front and rear measuring points are set along the main flow direction of the mixed liquid, and the time series of the first nitrite concentration at the front measuring point and the time series of the second nitrite concentration at the rear measuring point are periodically acquired. Based on the front-end measuring point and the rear-end measuring point, a front-end oxygen supply device and a rear-end oxygen supply device are configured respectively. Based on the changing trends of the first nitrite concentration time series and the second nitrite concentration time series, the oxygen supply line of the front-end oxygen supply device is controlled, and the short-term oxygen reduction control window of the rear-end oxygen supply device is controlled. Wherein, the oxygen supply line is the preset oxygen supply level executed by the front-end oxygen supply device, and the short-term oxygen reduction control window is the time arrangement for the back-end oxygen supply device to reduce or intermittently reduce oxygen supply. The method of controlling the oxygen supply line of the front-end oxygen supply device and the short-term oxygen reduction control window of the rear-end oxygen supply device based on the changing trends of the first and second nitrite concentration time series includes the following rules: At the beginning of a control cycle, the trend of nitrite concentration over time is evaluated based on the difference between at least two consecutive nitrite concentration sampling values ​​in the nitrite concentration time series of the previous control cycle. This trend is used to control the oxygen supply line of the oxygen supply device or the short-term oxygen reduction control window in the current control cycle. The stated trend of change is any one of the following: rising, falling, or stable. During any control cycle, the oxygen supply line of the upstream oxygen supply device and / or the short-term oxygen reduction control window of the downstream oxygen supply device are controlled by the following rules: If the trend of the second nitrite concentration time series in the previous control period is upward, then the short-term oxygen reduction control window of the downstream oxygen supply device will be opened or extended in the current control period, and the oxygen supply line of the upstream oxygen supply device will be maintained in the current control period. If the trend of the second nitrite concentration time series in the previous control period was decreasing or stable, then If the trend of the first nitrite concentration time series in the previous control cycle is upward, the short-term oxygen reduction control window of the downstream oxygen supply device will be terminated in the current control cycle, and the oxygen supply line of the upstream oxygen supply device will be increased in the current control cycle; otherwise... When the trend of the first nitrite concentration time series in the previous control cycle is decreasing or stable, the short-term oxygen reduction control window of the downstream oxygen supply device is terminated in the current control cycle, and the oxygen supply line of the upstream oxygen supply device is maintained in the current control cycle.

2. The greenhouse gas emission control method applied to wastewater nitrification treatment according to claim 1, characterized in that, The aerobic treatment unit is divided into a front micro-oxygen zone and a rear hypo-oxygen zone along the main flow direction of the mixture, wherein the oxygen supply target of the rear hypo-oxygen zone is lower than that of the front micro-oxygen zone. The front-end micro-oxygen zone is equipped with the front-end measuring point and the front-end oxygen supply device, and is supplied with oxygen by the front-end oxygen supply device. Its oxygen supply target is to ensure that the initial nitrification is not restricted. The rear-end low-oxygen zone is equipped with the rear-end measuring point and the rear-end oxygen supply device, and is supplied with oxygen by the rear-end oxygen supply device. Its oxygen supply target is to limit the transient accumulation of intermediate nitrogen oxides.

3. The greenhouse gas emission control method applied to wastewater nitrification treatment according to claim 1, characterized in that, The trend of nitrite concentration over time is assessed based on the difference between at least two consecutive nitrite concentration samples in the previous control period, using the following rules: When the cumulative residence time of the nitrite concentration time series within a steady-state band is not less than a preset duration, the change trend is determined to be stable. otherwise, When the cumulative residence time of the nitrite concentration time series within the steady state band is less than the preset duration, then when the proportion of sample pairs with a positive difference between two adjacent nitrite concentration sampling values ​​is not less than a preset proportion, the trend of change is determined to be upward. otherwise, When the proportion of sample pairs with a positive difference between two adjacent nitrite concentration samples is less than a preset proportion, the trend is determined to be downward.

4. The greenhouse gas emission control method applied to wastewater nitrification treatment according to claim 1, characterized in that, The anoxic treatment unit implemented in the aforementioned wastewater nitrification treatment system also includes at least the following steps: An equivalent electron donor dosing device is installed at the downstream boundary of the anoxic treatment unit along the mainstream direction of the mixed liquor. During the current control cycle, based on the time-series changes in the total nitrogen margin and second nitrite concentration in the effluent of the wastewater nitrification treatment system during the previous control cycle, the equivalent electron donor dosing device is controlled to add an equivalent electron donor. The equivalent electron donor is a substance that provides a reducing equivalent to nitrate and / or nitrite during the denitrification process. Based on the time series changes in the total nitrogen margin and second nitrite concentration in the effluent of the wastewater nitrification treatment system during the previous control period, the equivalent electron donor dosing device is controlled to add an equivalent electron donor, according to the following rules: At the start of a control cycle, if the total nitrogen margin in the effluent during the previous control cycle is not less than a preset margin, and the second nitrite concentration time series is determined to be rising or stable, then the equivalent electron donor is added by the equivalent electron donor addition device in the current control cycle.

5. The greenhouse gas emission control method applied to wastewater nitrification treatment according to claim 4, characterized in that, The equivalent electron donor delivery device delivers the equivalent electron donor via pulsed delivery.

6. A greenhouse gas emission control system applied to wastewater nitrification treatment, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, it performs the greenhouse gas emission control method for wastewater nitrification treatment as described in any one of claims 1-5.

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