Landfill leachate treatment method, device and system

Abstract

The application relates to the technical field of landfill leachate treatment, in particular to a landfill leachate treatment method, device and system, which comprises the following steps: collecting operating current and instantaneous flow, calculating a feed flow characteristic index, and constructing a dosing load sequence; collecting the pH values of the effluent end and the influent end of an anoxic tank, constructing an acid-base difference value response sequence, calculating waveform trend similarity, collecting the ORP values of different monitoring points of the anoxic tank, and assigning values to the denitrification end point values at the collection time; combining the waveform trend similarity, determining a reference frequency instruction, superimposing a preset sinusoidal wave signal, obtaining an output frequency instruction of a dosing pump frequency converter, and realizing accurate regulation and control of the carbon source dosing amount of the leachate. The application improves the accuracy of carbon source dosing amount regulation and control in the landfill leachate treatment process.

Description

Technical Field

[0001] This application relates to the field of landfill leachate treatment technology, specifically to a method, apparatus and system for treating landfill leachate. Background Technology

[0002] Landfill leachate treatment is a technical challenge in the field of environmental engineering. Due to the imbalance of carbon and nitrogen ratios in leachate from aging landfills, denitrification requires the addition of external carbon sources. In practical engineering, using concentrated leachate or fresh leachate from waste incineration plants as supplementary carbon sources is an economical and efficient synergistic treatment method with significant engineering application value.

[0003] However, this method faces two major technical challenges that hinder precise control of carbon source dosage, thus limiting its widespread adoption. The first challenge is the complex and fluctuating composition of the carbon source, which often contains high concentrations of suspended solids (SS), grease, and other impurities. These impurities can clog conveying equipment, alter fluid rheological properties, and prevent flow meters from accurately reflecting actual COD. Furthermore, impurities entering the biological system can lead to membrane fouling and sludge deactivation, exacerbating the uncertainty of dosage. The second challenge is the fluctuating hydraulic retention time in the anoxic tank, resulting in a time-varying lag between carbon source dosage and biological response. Traditional control methods are ill-suited to this, easily causing oscillations. Additionally, the high background alkalinity of aged leachate can overwhelm pH change signals, leading to sensor data distortion and control system failure. In summary, the addition of complex carbon sources presents problems of large material fluctuations and uncertain signal lag, affecting leachate denitrification and system stability. Therefore, a technical solution for precise control of carbon source dosage is urgently needed. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a method, apparatus, and system for treating landfill leachate, the specific technical solution of which is as follows: In a first aspect, embodiments of this application provide a method for treating landfill leachate, the method comprising the following steps: The operating current and instantaneous flow rate are collected at each collection time within each control cycle. The feed rheological characteristic index at the collection time is calculated. The feed rheological characteristic index is used to characterize the net energy consumption per unit flow rate. Based on the feed rheological characteristic index, the loading load sequence at the collection time is constructed. The pH values ​​at the effluent and influent ends of the anoxic tank were collected to construct an acid-base difference response sequence at the time of collection. Based on the similarity of the change trends of the loading sequence and the acid-base difference response sequence at the time of collection, as well as the differences of different values ​​in the same sequence, the waveform trend similarity at the time of collection was calculated. The ORP values ​​at different monitoring points in the anoxic tank were collected, and the denitrification endpoint value at the time of collection was assigned based on the rate of change of the ORP values ​​at adjacent monitoring points. Based on the waveform trend similarity and denitrification endpoint value at the sampling time, the reference frequency command for the next adjacent sampling time is determined. A preset sine wave signal is superimposed to obtain the output frequency command of the dosing pump inverter at the sampling time, thereby achieving precise control of the carbon source addition amount of landfill leachate.

[0005] Furthermore, the process for determining the feed rheological characteristic index is as follows: Based on all operating currents and instantaneous flow rates within the duration of the preset data segment preceding the acquisition time, the average operating current and average delivery flow rate at the acquisition time are determined respectively. The ratio of the difference between the average operating current at the time of sampling and the reference current measured by the pump when it is conveying clean water to the average conveying flow rate is denoted as the feed rheological characteristic index at the time of sampling.

[0006] Furthermore, the loading sequence is composed of the standardized processing results of the feed rheological characteristic index at different acquisition times.

[0007] Furthermore, the construction process of the acid-base difference response sequence is as follows: The pH difference between the outlet and inlet of the anoxic pool at the time of sampling is recorded as the acid-base reversal rate at the time of sampling; the acid-base difference response sequence is composed of the standardized processing results of the acid-base reversal rates at different sampling times.

[0008] Furthermore, the method for calculating the waveform trend similarity is as follows: Calculate the standard deviation of the values ​​in the loading sequence and the acid-base difference response sequence respectively. When one of the two standard deviations is less than the preset quiescent state constant, assign a waveform trend similarity value of 1.0 to the acquisition time. Conversely, based on the similarity between the loading sequence and the acid-base difference response sequence at the acquisition time, the waveform trend similarity at the acquisition time is calculated.

[0009] Furthermore, the specific steps for calculating the waveform trend similarity at the acquisition time based on the similarity between the loading sequence and the acid-base difference response sequence at the acquisition time are as follows: The negative correlation between the DTW distance of the load sequence and the acid-base difference response sequence at the acquisition time is denoted as the waveform trend similarity at the acquisition time.

[0010] Furthermore, the specific steps for assigning the denitrification endpoint value at the collection time are as follows: ORP values ​​were collected at the beginning, middle, and end points of the anoxic pool along the water flow direction. When there is a rate of change of ORP value at adjacent monitoring points that is greater than the preset mutation threshold, if the adjacent monitoring points corresponding to the rate of change of ORP value are the front end point and the middle end point, the denitrification endpoint value at the time of collection will be assigned to 1; if the adjacent monitoring points corresponding to the rate of change of ORP value are the middle end point and the end point, the denitrification endpoint value at the time of collection will be assigned to 2. When the rate of change of ORP values ​​at adjacent monitoring points is less than or equal to the preset mutation threshold, the denitrification endpoint value at the time of collection is assigned the value of 3.

[0011] Furthermore, the process for determining the reference frequency command for the next adjacent acquisition time after the acquisition time is as follows: When the waveform trend similarity at the acquisition time is less than the preset validity threshold, the reference frequency command is not determined. When the waveform trend similarity at the acquisition time is greater than or equal to the validity threshold, the reference frequency command for the next adjacent acquisition time is calculated based on the denitrification endpoint value at the acquisition time and the preset frequency adjustment step size.

[0012] Secondly, embodiments of this application provide a landfill leachate treatment device, which includes: a dosing load determination module, a denitrification endpoint determination module, and a carbon source dosing amount control module.

[0013] The load determination module is used to collect the operating current and instantaneous flow rate at each collection time within each control cycle, calculate the feed rheological characteristic index at the collection time, the feed rheological characteristic index is used to characterize the net energy consumption per unit flow rate, and construct the load sequence at the collection time based on the feed rheological characteristic index. The denitrification endpoint determination module is used to collect pH values ​​at the effluent and influent ends of the anoxic tank, construct an acid-base difference response sequence at the collection time, calculate the waveform trend similarity at the collection time based on the similarity of the change trend between the loading sequence and the acid-base difference response sequence at the collection time, as well as the difference between different values ​​in the same sequence, collect ORP values ​​at different monitoring points in the anoxic tank, and assign the denitrification endpoint value at the collection time based on the rate of change of ORP values ​​at adjacent monitoring points. The carbon source dosage control module is used to determine the reference frequency command for the next adjacent sampling time based on the waveform trend similarity and denitrification endpoint value at the sampling time, superimpose a preset sine wave signal, and obtain the output frequency command of the dosing pump inverter at the sampling time to achieve precise control of the carbon source dosage of landfill leachate.

[0014] Thirdly, embodiments of this application also provide a landfill leachate treatment system, the system including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0015] As can be seen from the above embodiments, the landfill leachate treatment method, apparatus, and system provided in this application have at least the following beneficial effects: This application considers the inherent mechanical resistance and electrical losses of pumps operating while conveying clean water. It assesses the net energy consumption per unit flow rate, determines the feed rheological characteristic index at the sampling time, and determines the viscous resistance of the fluid at the sampling time as the feed rheological characteristic index increases. Based on the net energy consumption assessment results and the feed rheological characteristic index, a loading sequence for the sampling time is constructed. The net change in pH after the fluid passes through the anoxic tank is calculated, and the pH difference response sequence is obtained. Since the hydraulic residence time in the anoxic tank varies with flow rate under variable flow conditions, the reliability of the data at the sampling time is verified. Based on the correlation between the loading sequence and the pH difference response sequence, the possibility of sensor distortion or strong interference at the sampling time is assessed, waveform trend similarity is obtained, and the OR of adjacent monitoring points is considered. The rate of change of the P-value determines the denitrification reaction process at the time of sampling, so as to decide whether to increase, decrease, or maintain the carbon source addition, and complete the assignment of the denitrification endpoint value, which is used to reflect the denitrification reaction process. Furthermore, based on the waveform trend similarity and the denitrification endpoint value at the time of sampling, and on the premise of verifying the addition effect at the time of sampling, a reference frequency command is determined to achieve load optimization adjustment. Finally, in order to prevent the occurrence of control dead zone under steady state, a preset sine wave signal is actively introduced as an excitation signal to obtain the output frequency command of the addition pump frequency converter at the time of sampling, so as to achieve precise control of the carbon source addition amount of landfill leachate, solve the problem of poor denitrification effect and system instability caused by large material fluctuations and signal lag uncertainty when adding complex component carbon sources, and improve the accuracy of carbon source addition amount control. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1A flowchart illustrating the steps of a landfill leachate treatment method according to one embodiment of this application; Figure 2 This is a schematic diagram of a landfill leachate treatment device provided in one embodiment of this application. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by this application in order to achieve the intended purpose of the invention, the following detailed description, in conjunction with the accompanying drawings and preferred embodiments, describes the specific implementation, structure, features and effects of a landfill leachate treatment method, apparatus and system proposed in this application.

[0019] The following description, in conjunction with the accompanying drawings, details a specific scheme for a landfill leachate treatment method, apparatus, and system provided in this application.

[0020] Please see Figure 1 The diagram illustrates a flowchart of a landfill leachate treatment method according to an embodiment of this application, the method comprising the following steps: S001: Collect the operating current and instantaneous flow rate at each collection time within each control cycle, calculate the feed rheological characteristic index at the collection time, the feed rheological characteristic index is used to characterize the net energy consumption per unit flow rate, and construct the load sequence at the collection time based on the feed rheological characteristic index.

[0021] At each acquisition time within each control cycle, the operating current is read from the frequency converter of the injection pump through industrial communication protocols such as Modbus or Profibus, and the instantaneous flow rate is read using an electromagnetic flow meter. The average value of all operating currents and the average value of instantaneous flow rates within the duration of the preset data segment preceding the acquisition time are recorded as the average operating current and average delivery flow rate at the acquisition time, respectively.

[0022] In this embodiment, a control cycle is set to 60 seconds, the sampling frequency is set to 1Hz, and the duration of a data segment is set to 5 seconds; the units for average operating current and average transmission flow are A and respectively. .

[0023] It is important to understand that, considering the high-frequency electromagnetic noise of frequency converters and the instantaneous fluctuations caused by fluid pulsation in industrial settings, directly using the operating current and instantaneous flow rate may lead to subsequent calculation errors. Therefore, by using the average value to determine the average operating current and average delivery flow rate at the time of data collection, the periodic pressure fluctuations caused by the pump impeller rotation are effectively smoothed out, ensuring that subsequent calculations are based on the steady-state characteristics of fluid delivery.

[0024] The pump's operating current is affected not only by fluid viscosity but also by factors such as mechanical friction and no-load loss. Therefore, a reference current is introduced to correct the average operating current and average delivery flow rate at the time of data collection, and the feed rheological characteristic index at the time of data collection is calculated.

[0025] The ratio of the difference between the average operating current at the time of sampling and the reference current measured by the pump when it is conveying clean water to the average conveying flow rate is denoted as the feed rheological characteristic index at the time of sampling.

[0026] The reference current measured by the pump under clean water operation represents the inherent mechanical resistance and electrical losses of the system. Therefore, the difference between the average operating current and the reference current measured by the pump under clean water operation only reflects the net current increment caused by fluid transport resistance. The feed rheological characteristic index at the sampling time represents the net energy consumption per unit flow rate. The larger the feed rheological characteristic index, the greater the viscous resistance of the fluid at the corresponding sampling time during transport.

[0027] In the process of calculating the ratio, to avoid the denominator being zero, a preset value needs to be added to the denominator. An example of this preset value is... .

[0028] It is important to note that, based on specific engineering experience in landfill leachate treatment, in scenarios such as concentrate reinjection, high organic loading in the feed is usually accompanied by high suspended solids and oil content, exhibiting significant rheological resistance characteristics. Therefore, the feed rheological characteristic index is used as an engineering-related characteristic quantity to characterize pollutant concentration fluctuations. Although the two are not directly causally related in terms of physical mechanisms, they show a waveform correlation in statistics and can be used for trend verification in the absence of online water quality analyzers. Among these, the rheological resistance characteristic is viscosity.

[0029] To prevent abnormally high-viscosity materials such as sludge clumps and sediments from entering the system and causing pipe blockage or membrane module fouling, protective judgments are executed based on the feed rheological characteristic index.

[0030] When the feed rheological characteristic index at the time of data acquisition exceeds a preset safety threshold, the feed physical properties at that time are deemed abnormal, triggering the shutdown protection logic. This involves sending a shutdown command to the frequency converter, forcibly stopping the feed pump, and outputting an alarm signal to prompt the operator to check the pipeline or replace the carbon source. It can be understood that when the feed rheological characteristic index at the time of data acquisition exceeds the preset safety threshold, the feed pump stops operating; that is, the value of the reference frequency command at the time of data acquisition is zero.

[0031] When the feed rheological characteristic index at the time of data collection is less than or equal to the preset safety threshold, the feed is determined to be normal, and the analysis continues.

[0032] The safety threshold is determined through on-site clean water calibration experiments. Specifically, the calibration method for the safety threshold is as follows: During the system commissioning phase, standard clean water is pumped, and the maximum value of the rheological characteristic index corresponding to different flow rates is recorded. The safety threshold value should be greater than or equal to the product of the maximum value and 1.2, and less than or equal to the product of the maximum value and 1.5, to allow for normal operational fluctuations. In this embodiment, the safety threshold value is the product of the maximum value and 1.4.

[0033] The standardized results of the feed rheological characteristic index at the time of acquisition and all acquisition times within a preset time period before the acquisition time are arranged sequentially to obtain the loading sequence at the acquisition time.

[0034] In this embodiment, the preset duration is set to 60 minutes, and the preset duration should be greater than or equal to 0.5 times the design hydraulic retention time of the anoxic pool.

[0035] It is important to note that if the system runtime is less than the preset duration before the data acquisition time, the feed rheological characteristic index of each spare data acquisition time will be assigned the feed rheological characteristic index of the data acquisition time. This is to ensure the integrity of the load sequence at the data acquisition time and avoid program crashes caused by the inability to calculate.

[0036] At this point, the load sequence at the acquisition time has been obtained.

[0037] S002: Collect pH values ​​at the effluent and influent ends of the anoxic tank, construct an acid-base difference response sequence at the collection time, calculate the waveform trend similarity at the collection time based on the similarity of the change trend between the loading sequence and the acid-base difference response sequence at the collection time, as well as the difference between different values ​​in the same sequence, collect ORP values ​​at different monitoring points in the anoxic tank, and assign the denitrification endpoint value at the collection time based on the rate of change of ORP values ​​at adjacent monitoring points.

[0038] The pH values ​​at the outlet and inlet of the anoxic pool were collected at each sampling time. The difference between the pH values ​​at the outlet and inlet of the anoxic pool at the sampling time was recorded as the acid-base reversal rate at the sampling time.

[0039] The acid-base reversal rate at the sampling time reflects the net change in pH of the fluid after passing through the anoxic tank for biochemical reactions. Since aged leachate usually has a high background alkalinity, the pH readings at the effluent and influent ends of a single anoxic tank fluctuate very little and are easily affected by influent fluctuations. However, the acid-base reversal rate at the sampling time with a determined difference can effectively offset this common-mode interference and highlight the subtle changes caused by the biochemical reactions.

[0040] The standardized processing results of acid-base reversal rates at the acquisition time and all acquisition times within a preset time period before the acquisition time are arranged sequentially to obtain the acid-base difference response sequence at the acquisition time.

[0041] It is important to note that if the system runtime is less than the preset duration before the acquisition time, the acid-base reversal rate of each spare acquisition time will be assigned the acid-base reversal rate of the acquisition time to ensure the integrity of the acid-base difference response sequence at the acquisition time and avoid program crashes caused by inability to calculate.

[0042] It is understandable that standardization was performed during the determination of the feed load sequence and the acid-base difference response sequence at the acquisition time. This standardization process aims to eliminate differences in dimensions and amplitude between the feed load sequence and the acid-base difference response sequence. This embodiment uses the Z-Score standard normalization method to standardize the feed rheological characteristic index and the acid-base reversal rate. In practical applications, implementers can use other methods such as the maximum-minimum normalization method for standardization; this is not limited here.

[0043] In particular, to avoid computational overflow during the standardization process, before performing the standardization process, the standard deviations of the feed rheological characteristic index and the acid-base reversal rate are calculated for the sampling time and all sampling times within a preset time period before the sampling time. When one of the two standard deviations is less than the preset quiescent state constant, the waveform trend similarity at the sampling time is assigned a value of 1.0. Otherwise, the waveform trend similarity at the sampling time is calculated based on the similarity between the changing trends of the loading sequence and the acid-base difference response sequence at the sampling time.

[0044] In this embodiment, the value of the silent state constant is... .

[0045] Under variable flow conditions, the hydraulic retention time (HRT) in anoxic tanks expands and contracts with changes in flow rate. This means that when a peak in the loading sequence is transmitted to the acid-base difference response sequence, there will not only be a time delay, but the waveform width may also be stretched or compressed. Conventional linear matching methods, such as Euclidean distance or cross-correlation, require strict alignment of the waveforms of the two sequences on the time axis, which cannot handle this nonlinear time distortion. To solve this problem, the DTW (Dynamic Time Warping) algorithm is used to nonlinearly warp the time axis to find the optimal matching path between the two sequences. Specifically, a stretched waveform indicates a smaller flow rate and a longer HRT, while a compressed waveform indicates a larger flow rate and a shorter HRT. Using the DTW algorithm to obtain the DTW distance between the two sequences is a well-known technique and will not be elaborated further.

[0046] When both standard deviations are greater than or equal to the standard deviation of the preset quiescent state constant, the negative correlation processing result of the DTW distance between the applied load sequence and the acid-base difference response sequence at the acquisition time is recorded as the waveform trend similarity at the acquisition time.

[0047] It is understood that negative correlation processing is applied to the DTW distance between the loading sequence and the acid-base difference response sequence at the acquisition time, ensuring that the DTW distance is negatively correlated with the waveform trend similarity at the acquisition time. It is understood that the negative correlation in this application refers to the relationship between the independent and dependent variables. The independent variable is the DTW distance between the loading sequence and the acid-base difference response sequence at the acquisition time, and the dependent variable is the waveform trend similarity at the acquisition time. The negative correlation means that the dependent variable decreases (increases) as the independent variable increases (decreases), and can be an inverse proportional relationship, a subtraction relationship, etc.

[0048] Preferably, as an embodiment of this application, when both standard deviations are greater than or equal to the standard deviation of the preset quiescent state constant, the ratio of the DTW distance between the loading sequence and the acid-base difference response sequence at the acquisition time to the number of feed rheological characteristic indices contained in the loading sequence is recorded as the relative difference between loading and acid-base difference at the acquisition time, and the reciprocal of the sum of the relative difference between loading and acid-base difference at the acquisition time and the number 1 is recorded as the waveform trend similarity at the acquisition time.

[0049] In the process of calculating the relative difference between the feed load and the acid-base difference at the time of data collection, dividing by the number of feed rheological characteristic indices contained in the feed load sequence serves to eliminate the influence of sequence length on the similarity evaluation of the sequence's trend.

[0050] The waveform trend similarity at the acquisition time is used to verify the reliability of the data at that time. Specifically: the closer the waveform trend similarity value at the acquisition time is to 1, the more similar the morphology of the applied load sequence and the acid-base difference response sequence at the acquisition time are, and the more similar their changing trends are, the greater the likelihood that the data collected by the sensor at the acquisition time is true and valid; conversely, the closer the waveform trend similarity value at the acquisition time is to 0, the less correlated the changing trends of the applied load sequence and the acid-base difference response sequence are, and the greater the likelihood that the sensor is distorted or subjected to strong interference at the acquisition time.

[0051] Furthermore, the denitrification reaction progress at the time of data collection is determined to decide whether to increase, decrease, or maintain the carbon source addition. Specifically, ORP redox potential sensors distributed along the process are used to pinpoint the reaction endpoint.

[0052] The ORP values ​​of three monitoring points distributed along the water flow direction in the anoxic pool are collected. The three monitoring points include the front point A, the middle point B, and the end point C. The rate of change of the ORP values ​​of adjacent monitoring points is calculated. Based on the rate of change of the ORP values ​​of adjacent monitoring points, the denitrification endpoint value at the time of collection is assigned.

[0053] When the rate of change of ORP values ​​at adjacent monitoring points at the time of sampling exceeds a preset mutation threshold, the adjacent monitoring points corresponding to the rate of change of ORP values ​​are determined. Specifically, when the adjacent monitoring points corresponding to the rate of change of ORP values ​​are the front-end point A and the middle-end point B, the denitrification endpoint value at the time of sampling is assigned a value of 1; when the adjacent monitoring points corresponding to the rate of change of ORP values ​​are the middle-end point B and the end point C, the denitrification endpoint value at the time of sampling is assigned a value of 2; when the rate of change of ORP values ​​at adjacent monitoring points is less than or equal to the preset mutation threshold, the denitrification endpoint value at the time of sampling is assigned a value of 3. It should be noted that when the rate of change of ORP values ​​at the front-end point and the middle-end point, and the middle-end point and the end point are both greater than the preset mutation threshold, the mutation at the front end of the water flow is selected first, that is, the denitrification endpoint value is assigned a value of 1.

[0054] In this embodiment, the mutation threshold is set to 50mV / segment. At the acquisition time corresponding to the rate of change of ORP value of adjacent monitoring points that is greater than the preset mutation threshold, electron acceptors such as nitrate in the reaction system are depleted. This acquisition time is the moment when the system potential jumps, i.e., the nitrate knee point.

[0055] It's important to understand that if the denitrification endpoint value at the sampling time is 1, the denitrification reaction has already completed prematurely at the front end of the tank. This means that excessive carbon source was added at the sampling time, and most of the carbon source was lost without being utilized. If the denitrification endpoint value at the sampling time is 2, the reaction is completed in the middle to later stages of the tank, which is the ideal state, ensuring sufficient nitrogen removal while avoiding carbon source waste. If the denitrification endpoint value at the sampling time is 3, and no gradient change was detected throughout the entire process, the reaction is not yet complete until the effluent. This means that insufficient carbon source was added at the sampling time, posing a risk of excessive total nitrogen in the effluent.

[0056] At this point, the denitrification endpoint value at the time of collection is obtained.

[0057] S003: Based on the waveform trend similarity and denitrification endpoint value at the acquisition time, determine the reference frequency command for the next adjacent acquisition time, superimpose the preset sine wave signal, obtain the output frequency command of the dosing pump inverter at the acquisition time, and realize the precise control of the carbon source addition amount of landfill leachate.

[0058] In order to adjust the load under the premise of safe feeding and reliable sensor data, the feeding effect at the time of acquisition is verified by the similarity of the waveform trend at the acquisition time.

[0059] When the waveform trend similarity at the sampling time is less than the validity threshold, it is determined that the biochemical response waveform at the sampling time is seriously mismatched with the dosing action waveform. The reference frequency command of the next adjacent sampling time is not calculated. Instead, the dosing frequency of the carbon source of the leachate at the sampling time is directly assigned as the dosing frequency of the previous adjacent sampling time, and an instrument maintenance warning signal is output. At this time, the sensor probe is covered by oil, causing the reading to be distorted, or the biochemical system is inhibited by toxicity and loses its normal response capability. The determined denitrification endpoint value is unreliable.

[0060] The validity threshold is set based on the statistical distribution of historical valid operating data. Specifically, a segment of historical data that has been manually confirmed to be operating normally and meeting water quality standards is selected. The waveform trend similarity of all collection times within this period is calculated, and the lower quartile of its statistical distribution is taken as the validity threshold. In this embodiment, the validity threshold is set to 0.6.

[0061] When the waveform trend similarity at the sampling time is greater than or equal to the effectiveness threshold, the reference frequency command for the next adjacent sampling time is determined based on the denitrification endpoint value at the sampling time, thereby achieving load optimization regulation.

[0062] Specifically, when the denitrification endpoint value at the sampling time is 1, the carbon source dosage is excessive, and a reduction operation is performed. The difference between the reference frequency command at the sampling time and the preset frequency adjustment step size is used as the reference frequency command for the next adjacent sampling time. When the denitrification endpoint value at the sampling time is 2, the carbon source dosage just meets the biochemical requirements, and the reference frequency command at the sampling time is used as the reference frequency command for the next adjacent sampling time. When the denitrification endpoint value at the sampling time is 3, the carbon source dosage is insufficient, and the sum of the reference frequency command at the sampling time and the preset frequency adjustment step size is used as the reference frequency command for the next adjacent sampling time.

[0063] The preset frequency adjustment step size is set according to the effective volume of the anoxic pool and the rated flow rate of the pump, and is usually 1% to 2% of the rated frequency of the pump. In this embodiment, the preset frequency adjustment step size is 0.5Hz.

[0064] This enables the adaptive determination of the carbon source dosage for landfill leachate treatment.

[0065] It is worth noting that when the denitrification endpoint value is 2 at all sampling times within the preset stable duration, the variance of each feed rheological characteristic index corresponding to the loading sequence at the sampling time approaches zero, which may lead to the failure of standardization processing or the inability of the dynamic time warping algorithm to extract an effective control dead zone. In order to break this quiescent state, an excitation signal is actively introduced to prevent the control dead zone from failing under steady state.

[0066] In this embodiment, the preset stable duration is set to 1 hour.

[0067] A sinusoidal signal with a preset probe amplitude is generated, denoted as the fluctuation probe signal. This fluctuation probe signal is superimposed on the reference frequency command of the next adjacent acquisition time to obtain the inverter's output frequency command at the acquisition time. The formula for calculating the inverter's output frequency command at the acquisition time is: in, Indicates the time of data collection The output frequency command of the frequency converter; Indicates the first Reference frequency command for each acquisition moment; This indicates the probe amplitude; in this embodiment, the probe amplitude is set to 0.2Hz. This indicates the probe period; in this embodiment, the probe period is set to 30 minutes. Represents the sine function; This represents pi (π), and is rounded to two decimal places in calculations.

[0068] Specifically, the probe amplitude should be less than 50% of the frequency adjustment step size and greater than the sensor's detection noise floor to ensure that it can cause identifiable fluctuations. In order to ensure that the probe signal can penetrate the reactor and be detected at the effluent end, the probe period should be greater than 50% of the current average hydraulic retention time of the anoxic tank to ensure that the fluctuation characteristics can be completely transmitted to the sensor.

[0069] It is important to understand that the power supply frequency output by the frequency converter to the pump motor can control the motor speed and pump flow rate, thereby achieving precise control of the carbon source dosage.

[0070] This enables precise control of the amount of carbon source added to landfill leachate.

[0071] Please see Figure 2 , Figure 2 This is a schematic diagram of a landfill leachate treatment device according to one embodiment of this application. In this embodiment, the devices include units that perform the steps in an embodiment corresponding to a landfill leachate treatment method. See also... Figure 2 The leachate treatment device includes: a dosing load determination module, a denitrification endpoint determination module, and a carbon source dosing control module.

[0072] The load determination module is used to collect the operating current and instantaneous flow rate at each collection time within each control cycle, calculate the feed rheological characteristic index at the collection time, the feed rheological characteristic index is used to characterize the net energy consumption per unit flow rate, and construct the load sequence at the collection time based on the feed rheological characteristic index. The denitrification endpoint determination module is used to collect pH values ​​at the effluent and influent ends of the anoxic tank, construct an acid-base difference response sequence at the collection time, calculate the waveform trend similarity at the collection time based on the similarity of the change trend between the loading sequence and the acid-base difference response sequence at the collection time, as well as the difference between different values ​​in the same sequence, collect ORP values ​​at different monitoring points in the anoxic tank, and assign the denitrification endpoint value at the collection time based on the rate of change of ORP values ​​at adjacent monitoring points. The carbon source dosage control module is used to determine the reference frequency command for the next adjacent sampling time based on the waveform trend similarity and denitrification endpoint value at the sampling time, superimpose a preset sine wave signal, and obtain the output frequency command of the dosing pump inverter at the sampling time to achieve precise control of the carbon source dosage of landfill leachate.

[0073] Based on the same inventive concept as the above methods, this application also provides a landfill leachate treatment system, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described landfill leachate treatment methods.

[0074] It is understood that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0075] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0076] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.

Claims

1. A method for treating landfill leachate, characterized in that, The method includes the following steps: The operating current and instantaneous flow rate of the delivery pump are collected at each collection time within each control cycle. The feed rheological characteristic index at the collection time is calculated. The feed rheological characteristic index is used to characterize the net energy consumption per unit flow rate. Based on the feed rheological characteristic index, the loading load sequence at the collection time is constructed. The pH values ​​at the outlet and inlet of the anoxic tank were collected to construct an acid-base difference response sequence at the time of collection. Based on the similarity of the change trend between the loading sequence and the acid-base difference response sequence at the time of collection, as well as the difference between different values ​​in the same sequence, the waveform trend similarity at the time of collection was calculated. The ORP values ​​at different monitoring points in the anoxic tank were collected. Based on the rate of change of the ORP values ​​at adjacent monitoring points, the denitrification endpoint value at the time of collection was assigned. The different monitoring points are three monitoring points distributed along the water flow direction in the anoxic tank. Based on the waveform trend similarity and denitrification endpoint value at the time of collection, the reference frequency command for the next adjacent time of collection is determined, and a preset sine wave signal is superimposed to obtain the output frequency command of the dosing pump frequency converter at the time of collection, so as to achieve precise control of the carbon source addition amount of landfill leachate. The process for determining the feed rheological characteristic index is as follows: Based on all operating currents and instantaneous flow rates within the duration of the preset data segment preceding the acquisition time, the average operating current and average delivery flow rate at the acquisition time are determined respectively. The ratio of the difference between the average operating current at the time of sampling and the reference current measured by the pump when it is conveying clean water to the average conveying flow rate is denoted as the feed rheological characteristic index at the time of sampling. The standardized results of the feed rheological characteristic index at the time of acquisition and all acquisition times within a preset time period before the acquisition time are arranged sequentially to obtain the loading sequence at the acquisition time.

2. The landfill leachate treatment method as described in claim 1, characterized in that, The loading sequence is composed of the standardized processing results of the feed rheological characteristic index at different acquisition times.

3. The landfill leachate treatment method as described in claim 1, characterized in that, The process of constructing the acid-base difference response sequence is as follows: The pH difference between the outlet and inlet of the anoxic pool at the time of sampling is recorded as the acid-base reversal rate at the time of sampling; the acid-base difference response sequence is composed of the standardized processing results of the acid-base reversal rates at different sampling times.

4. The landfill leachate treatment method as described in claim 1, characterized in that, The method for calculating the waveform trend similarity is as follows: Calculate the standard deviation of the values ​​in the loading sequence and the acid-base difference response sequence respectively. When one of the two standard deviations is less than the preset quiescent state constant, assign a waveform trend similarity value of 1.0 to the acquisition time. Conversely, based on the similarity between the loading sequence and the acid-base difference response sequence at the acquisition time, the waveform trend similarity at the acquisition time is calculated.

5. A method for treating landfill leachate as described in claim 4, characterized in that, The specific steps for calculating the waveform trend similarity at the acquisition time based on the similarity between the loading sequence and the acid-base difference response sequence at the acquisition time are as follows: The negative correlation between the DTW distance of the load sequence and the acid-base difference response sequence at the acquisition time is denoted as the waveform trend similarity at the acquisition time.

6. The landfill leachate treatment method as described in claim 1, characterized in that, The specific steps for assigning the denitrification endpoint value at the time of collection are as follows: ORP values ​​were collected at the beginning, middle, and end points of the anoxic pool along the water flow direction. When there is a rate of change of ORP value at adjacent monitoring points that is greater than the preset mutation threshold, if the adjacent monitoring points corresponding to the rate of change of ORP value are the front end point and the middle end point, the denitrification endpoint value at the time of collection will be assigned to 1; if the adjacent monitoring points corresponding to the rate of change of ORP value are the middle end point and the end point, the denitrification endpoint value at the time of collection will be assigned to 2. When the rate of change of ORP values ​​at adjacent monitoring points is less than or equal to the preset mutation threshold, the denitrification endpoint value at the time of collection is assigned the value of 3.

7. A method for treating landfill leachate as described in claim 1, characterized in that, The process for determining the reference frequency command for the next adjacent acquisition time after the acquisition time is as follows: When the waveform trend similarity at the acquisition time is less than the preset validity threshold, the reference frequency command is not determined. When the waveform trend similarity at the acquisition time is greater than or equal to the validity threshold, the reference frequency command for the next adjacent acquisition time is calculated based on the denitrification endpoint value at the acquisition time and the preset frequency adjustment step size.

8. A landfill leachate treatment device, implementing the method as described in claim 1, characterized in that, The leachate treatment device includes: The load determination module is used to collect the operating current and instantaneous flow rate at each collection time within each control cycle, calculate the feed rheological characteristic index at the collection time, the feed rheological characteristic index is used to characterize the net energy consumption per unit flow rate, and construct the load sequence at the collection time based on the feed rheological characteristic index. The denitrification endpoint determination module is used to collect pH values ​​at the effluent and influent ends of the anoxic tank, construct an acid-base difference response sequence at the collection time, calculate the waveform trend similarity at the collection time based on the similarity of the change trend between the loading sequence and the acid-base difference response sequence at the collection time, as well as the difference between different values ​​in the same sequence, collect ORP values ​​at different monitoring points in the anoxic tank, and assign the denitrification endpoint value at the collection time based on the rate of change of ORP values ​​at adjacent monitoring points. The carbon source dosage control module is used to determine the reference frequency command for the next adjacent sampling time based on the waveform trend similarity and denitrification endpoint value at the sampling time, superimpose a preset sine wave signal, and obtain the output frequency command of the dosing pump inverter at the sampling time to achieve precise control of the carbon source dosage of landfill leachate.

9. A landfill leachate treatment system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-7.

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