Method for measuring denitrification efficiency of functional bacteria in urban sewage autotrophic denitrification system

Abstract

This invention provides a method for determining the denitrification efficiency of functional microbial communities in an autotrophic denitrification system for urban wastewater, belonging to the field of denitrification efficiency measurement technology. This invention involves preparing a double-layered embedded carrier and establishing a continuous flow reactor, calculating the total nitrogen removal rate and nitrogen removal rate of the influent and effluent; separately measuring the ammonia oxidation rate of the outer layer and the anaerobic ammonia oxidation rate of the inner layer, calculating the rate matching degree and matching deviation index to determine the imbalance type of the denitrification system; then measuring the structural parameters of the embedded carrier and calculating the contribution of the structural parameters to the matching deviation index; generating a basic denitrification efficiency score based on the total nitrogen removal rate and nitrogen removal efficiency, and correcting the basic denitrification efficiency score based on the contribution degree to obtain a mismatch penalty factor, resulting in a comprehensive denitrification efficiency index used to judge the denitrification effect of the system. This invention combines macroscopic denitrification effect with the degree of microscopic structural mismatch to form a standardized evaluation system, improving the accuracy and practicality of the assessment.

Description

Technical Field

[0001] This invention relates to the field of denitrification efficiency measurement technology, specifically to a method for measuring the denitrification efficiency of functional microbial communities in an autotrophic denitrification system for urban sewage. Background Technology

[0002] Currently, urban wastewater denitrification treatment generally relies on traditional heterotrophic denitrification processes, which suffer from problems such as strong carbon source dependence, high operating costs, and large sludge production. While autotrophic denitrification technology can achieve efficient and low-carbon denitrification, the activity of its functional microbial communities is easily affected by carrier structure, environmental conditions, and the spatial distribution of the microbial community, leading to unstable denitrification efficiency and difficulties in prediction and control. Existing assessment methods mostly focus on macroscopic water quality indicators or the activity of single microbial communities, lacking effective means to correlate carrier microstructure, microbial activity, and the overall denitrification efficiency of the system, making it difficult to achieve accurate assessment and optimized design of different denitrification systems.

[0003] In the prior art, publication number CN106348440A discloses a method for determining the denitrification contribution rate and activity of bacteria in a fully autotrophic denitrification process, including: reactor construction, sludge inoculation, reactor operation, calculation of denitrification contribution rate and activity. By setting up oxygen-limiting experiments and anaerobic experiments, the denitrification contribution rate of autotrophic denitrifying and anaerobic ammonia-oxidizing bacteria in the actual operating reactor and their activity under anaerobic conditions are determined respectively.

[0004] The main problems with the above scheme are: the detection work relies entirely on on-site experiments, requiring the addition of oxygen-limited and anaerobic control experimental groups, which makes the process complex and time-consuming, and does not support the large-scale rapid evaluation of denitrification systems under different operating conditions and with different carrier structures; moreover, it can only detect microbial community-related indicators under specific operating conditions, without combining carrier microstructure analysis, making it difficult to reveal the intrinsic relationship between carrier structure, microbial community distribution and denitrification efficiency.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the denitrification efficiency of functional microbial communities in an autotrophic denitrification system for urban wastewater, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for determining the denitrification efficiency of functional microbial communities in an autotrophic denitrification system for urban wastewater, comprising the following steps: Step 1: Prepare an embedded carrier consisting of a double-layer structure of an outer aerobic layer and an inner anaerobic layer, and establish a continuous flow reactor; Step 2: Collect influent and effluent samples from the continuous flow reactor and measure the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen to calculate the total nitrogen removal rate and nitrogen removal rate after the continuous flow reactor has been operating stably. Step 3: Measure the ammonia oxidation rate of the outer aerobic layer and the anaerobic ammonia oxidation rate of the inner anaerobic layer of the embedded carrier respectively. Calculate the rate matching degree and matching deviation index based on the ammonia oxidation rate and the anaerobic ammonia oxidation rate. Determine the imbalance type of the denitrification system based on the matching deviation index. Step 4: Measure the actual structural parameters of the embedding carrier, retrieve the baseline values ​​of each structural parameter under normal system operation, and calculate the contribution of each structural parameter in the denitrification system to the matching deviation index under different imbalance types. Step 5: Generate a basic score for denitrification efficiency based on the total nitrogen removal rate and nitrogen removal efficiency. Determine the mismatch penalty factor by combining the contribution of each structural parameter. Calculate the denitrification efficiency index based on the basic score and the mismatch penalty factor. Judge the denitrification effect of the system by using the denitrification efficiency index.

[0008] Furthermore, the principle of preparing an embedded carrier comprising an outer aerobic layer and an inner anaerobic layer, and establishing a continuous flow reactor, is as follows: A polyvinyl alcohol solution was mixed with an anaerobic ammonia-oxidizing bacteria solution to obtain a polyvinyl alcohol-anaerobic ammonia-oxidizing bacteria mixture. The mixture was added dropwise to a boric acid solution to initiate the first cross-linking process, forming preliminary carrier particles. A polyvinyl alcohol solution was mixed with an ammonia-oxidizing bacteria solution to obtain a polyvinyl alcohol-ammonia-oxidizing bacteria mixture. The initial carrier particles are immersed in a polyvinyl alcohol-ammonia oxidizing bacteria mixture to coat the outer layer of the particles with the ammonia oxidizing bacteria solution. Then, the coated carrier particles are immersed in a boric acid solution for a second cross-linking, forming a double-layered embedded carrier with an outer layer enriched with ammonia oxidizing bacteria and an inner layer enriched with anaerobic ammonia oxidizing bacteria. A continuous flow reactor was constructed using conventional processes, and an initial filling rate was preset. The prepared embedding carrier was then added into the continuous flow reactor according to the initial filling rate.

[0009] Furthermore, the principle for calculating the total nitrogen removal rate and nitrogen removal percentage after the continuous flow reactor has been operating stably is as follows: The wastewater to be treated is pumped into a continuous flow reactor. The influent water quality performance data before treatment and the effluent water quality performance data after treatment are measured daily. The water quality performance data include: ammonia nitrogen concentration, nitrite nitrogen concentration, nitrate nitrogen concentration and chemical oxygen demand. The total nitrogen concentration in the influent is the sum of the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the influent on that day, and the total nitrogen concentration in the effluent is the sum of the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the effluent on that day; The total nitrogen removal rate for the day is obtained by dividing the difference between the total nitrogen concentration in the influent and the total nitrogen concentration in the effluent by the total nitrogen concentration in the influent. The nitrogen removal efficiency is obtained by multiplying the difference in total nitrogen concentration between the influent and effluent by the influent flow rate and then dividing by the reactor volume. The target total nitrogen removal rate and the range of change of total nitrogen removal rate are preset, and the detection time window is set; When the total nitrogen removal rate of each day within the detection time window is greater than or equal to the target total nitrogen removal rate, and the absolute difference between the total nitrogen removal rates of any two adjacent days within the detection time window does not exceed the range of change in total nitrogen removal rate, the continuous flow reactor is determined to have reached a steady state. The average total nitrogen removal rate and average nitrogen removal efficiency of each day within the detection time window are calculated as the total nitrogen removal rate and nitrogen removal rate after the continuous flow reactor has been operating stably.

[0010] Furthermore, the rate matching degree and matching deviation index are calculated based on the ammonia oxidation rate and the anaerobic ammonia oxidation rate. The principle for determining the imbalance type of the denitrification system based on the matching deviation index is as follows: Divide the ammonia oxidation rate of the day by the anaerobic ammonia oxidation rate to obtain the rate matching degree of the day; The optimal rate matching degree is preset, and the matching deviation index for the day is obtained by dividing the rate matching degree of the day by the optimal rate matching degree and then taking the natural logarithm. A first imbalance threshold and a second imbalance threshold are set, wherein the first imbalance threshold is less than the second imbalance threshold, and the respective activity thresholds for ammonia oxidation rate and anaerobic ammonia oxidation rate are preset. Three imbalance types are distinguished based on the first imbalance threshold, the second imbalance threshold, the activity threshold of ammonia oxidation rate, and the activity threshold of anaerobic ammonia oxidation rate. The three imbalance types include ammonia oxidation relatively over-rate type, anaerobic ammonia oxidation relatively over-rate type, and bidirectional activity deficiency type. If the ammonia oxidation rate is less than the activity threshold of the ammonia oxidation rate, and the anaerobic ammonia oxidation rate is less than the activity threshold of the anaerobic ammonia oxidation rate, the imbalance type is determined to be a bidirectional activity deficiency type. Provided that the ammonia oxidation rate is greater than or equal to the activity threshold of the ammonia oxidation rate and the anaerobic ammonia oxidation rate is greater than or equal to the activity threshold of the anaerobic ammonia oxidation rate, if the matching deviation index is greater than the second imbalance threshold, the imbalance type is judged to be the ammonia oxidation relative overrate type. If the matching deviation index is less than the first imbalance threshold, the imbalance type is determined to be anaerobic ammonia oxidation relative overrate type. If the matching deviation index is between the first imbalance threshold and the second imbalance threshold, the denitrification system is not imbalanced.

[0011] Furthermore, the principle for calculating the contribution of each structural parameter to the matching deviation index under different imbalance types is as follows: The measured structural parameters of the embedded carrier include the measured values ​​of porosity and the measured values ​​of the inner and outer layer thickness ratio; Obtain the baseline values ​​of porosity and inner / outer layer thickness ratio when the denitrification system is in normal operating condition; The porosity deviation rate is obtained by subtracting the porosity reference value from the measured porosity value, taking the absolute value, and then dividing it by the porosity reference value. The deviation rate of the inner and outer layer thickness ratio is obtained by subtracting the reference value of the inner and outer layer thickness ratio from the measured value and then dividing the absolute value by the reference value of the inner and outer layer thickness ratio. Based on the imbalance type of the denitrification system, preset porosity influence coefficient and inner and outer layer thickness ratio influence coefficient are used. The contribution of porosity to the matching deviation index is calculated by multiplying the porosity influence coefficient by the porosity deviation rate. The contribution of the inner and outer layer thickness ratio to the matching deviation index is calculated by multiplying the inner and outer layer thickness ratio influence coefficient by the inner and outer layer thickness ratio deviation rate.

[0012] Furthermore, the principle for generating a basic score for denitrification efficiency based on total nitrogen removal rate and nitrogen removal efficiency is as follows: The total nitrogen removal rate and nitrogen removal efficiency are normalized separately. The normalized total nitrogen removal rate and normalized nitrogen removal efficiency are then weighted and summed to obtain the basic score of nitrogen removal efficiency. The weight of the normalized total nitrogen removal rate is lower than that of the normalized nitrogen removal efficiency, and the sum of the two weights is 1. The mismatch penalty factor is generated by combining the contribution of each structural parameter. The principle is as follows: The contribution of porosity to the matching deviation index and the contribution of the inner and outer layer thickness ratio to the matching deviation index are summed, and the minimum value between the summation result and value 1 is taken as the mismatch penalty factor.

[0013] Furthermore, the denitrification efficiency index is calculated based on the denitrification efficiency baseline score and the mismatch penalty factor. The principle for judging the denitrification effect of the system through the denitrification efficiency index is as follows: The adjustment factor is obtained by subtracting the mismatch penalty factor from 1, and the denitrification efficiency index is obtained by multiplying the adjustment factor by the denitrification efficiency base score. Set a first evaluation threshold and a second evaluation threshold, wherein the first evaluation threshold is less than the second evaluation threshold; If the denitrification efficiency index is greater than or equal to the second evaluation threshold, it indicates that the denitrification efficiency of the urban sewage autotrophic denitrification system is excellent. If the denitrification efficiency index is less than the first evaluation threshold, it indicates that the denitrification efficiency of the urban sewage autotrophic denitrification system is poor. If the denitrification efficiency index is between the first evaluation threshold and the second evaluation threshold, it indicates that the denitrification efficiency of the urban wastewater autotrophic denitrification system is moderate.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a double-layered embedded carrier paired with a continuous flow reactor, eliminating the need for a control group setup and enabling rapid, large-scale evaluation of the denitrification system. Simultaneously, it spatially separates and synergistically immobilizes two types of functional microbial communities, enhancing metabolic synergy and substrate mass transfer efficiency. By measuring the stratified reaction rate and calculating relevant matching indicators, the type of system imbalance can be determined. Combined with the carrier structural parameters, its impact on the system's operating state can be quantitatively analyzed, clarifying the underlying mechanism of action.

[0015] By further combining the contribution of structural parameters to the matching deviation index, integrating macroscopic denitrification indicators with microscopic structural deviations, and determining the basic score of denitrification efficiency based on total nitrogen removal rate and nitrogen removal efficiency, and calculating the comprehensive denitrification efficiency index with mismatch penalty factor, a standardized evaluation system is formed to improve the accuracy and practicality of denitrification system assessment. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram of the fitting curve of the total nitrogen removal rate of the present invention as a function of reaction days. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0018] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0019] Example: Please see Figures 1 to 2 The present invention provides a technical solution: A method for determining the denitrification efficiency of functional microbial communities in an autotrophic denitrification system for urban wastewater, comprising the following steps: Step 1: Prepare an embedded carrier consisting of a double-layer structure of an outer aerobic layer and an inner anaerobic layer, and establish a continuous flow reactor; In this embodiment, the principle of preparing an embedded carrier comprising an outer aerobic layer and an inner anaerobic layer, and establishing a continuous flow reactor, is as follows: A polyvinyl alcohol solution was mixed with an anaerobic ammonia-oxidizing bacteria solution to obtain a polyvinyl alcohol-anaerobic ammonia-oxidizing bacteria mixture. The mixture was added dropwise to a boric acid solution to initiate the first cross-linking process, forming preliminary carrier particles. A polyvinyl alcohol solution was mixed with an ammonia-oxidizing bacteria solution to obtain a polyvinyl alcohol-ammonia-oxidizing bacteria mixture. The initial carrier particles are immersed in a polyvinyl alcohol-ammonia oxidizing bacteria mixture to coat the outer layer of the particles with the ammonia oxidizing bacteria solution. Then, the coated carrier particles are immersed in a boric acid solution for a second cross-linking, forming a double-layered embedded carrier with an outer layer enriched with ammonia oxidizing bacteria and an inner layer enriched with anaerobic ammonia oxidizing bacteria. A two-step cross-linking and embedding method was used to construct an inner anaerobic ammonia-oxidizing bacteria core and an outer ammonia-oxidizing bacteria shell layer. The anaerobic ammonia-oxidizing bacteria were mixed with a polyvinyl alcohol solution and then dripped into a boric acid solution for the first cross-linking, forming preliminary carrier particles with a certain mechanical strength and enriched with anaerobic ammonia-oxidizing bacteria. The preliminary carrier particles were then coated with an outer layer, and the coated particles were immersed again in a boric acid solution to fix the outer layer, forming a stable, layered double-layer structure. The outer aerobic layer is enriched with ammonia-oxidizing bacteria, which oxidize ammonia nitrogen to nitrite nitrogen under aerobic conditions, while the inner anaerobic layer is enriched with anaerobic ammonia-oxidizing bacteria, which utilize nitrite nitrogen and ammonia nitrogen to generate nitrogen gas under anaerobic conditions.

[0020] A continuous flow reactor was constructed using conventional processes, and an initial filling rate was preset. The prepared embedding carrier was then added into the continuous flow reactor according to the initial filling rate.

[0021] The conventional process refers to a set of standard and universal engineering methods used in this field to construct a continuous flow reactor. Specifically, it involves: selecting an upflow continuous flow reactor; assembling the main body of the continuous flow reactor, reaction zone, inlet pipe, outlet pipe, aeration system, and online sampling interface according to process requirements; filling the reaction zone of the continuous flow reactor with the aforementioned double-layer embedded carrier; connecting the wastewater inlet; adjusting operating parameters such as hydraulic retention time, flow rate, and dissolved oxygen; and completing the construction and trial operation of the continuous flow reactor.

[0022] The initial filling rate refers to the percentage of the effective volume of the reaction zone occupied by the embedded carrier, pre-set according to process design requirements and added to the reactor at one time before the continuous flow reactor starts up. The initial filling rate determines the initial biomass of ammonia-oxidizing and anaerobic ammonia-oxidizing bacteria in the reactor, affecting whether the system can quickly establish a stable denitrification function. A higher filling rate increases the probability of contact between wastewater and the embedded carrier, and shortens the mass transfer path, which is beneficial to improving the synergistic efficiency of ammonia oxidation and anaerobic ammonia oxidation reactions. However, it may lead to tight stacking of the carriers, obstructing wastewater flow, and easily forming dead zones or short-circuiting in some areas. This can result in ammonia nitrogen or nitrite nitrogen not being able to effectively reach the inner anaerobic zone, leading to insufficient supply of reactants in the inner layer, resulting in nitrite nitrogen accumulation or a decrease in nitrogen removal rate. A lower filling rate indicates a smaller number of functional bacteria in the reactor, limited system denitrification capacity, and nitrite nitrogen may not be utilized by the inner layer in time, leading to nitrite nitrogen leakage. As an implementation method, the initial filling rate ranges from 25% to 35%, and the specific value is set by technicians according to the actual situation, without limitation.

[0023] Step 2: Collect influent and effluent samples from the continuous flow reactor and measure the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen to calculate the total nitrogen removal rate and nitrogen removal rate after the continuous flow reactor has been operating stably. In this embodiment, the principle for calculating the total nitrogen removal rate and nitrogen removal rate after the continuous flow reactor has been operating stably is as follows: The wastewater to be treated is pumped into a continuous flow reactor. The influent water quality performance data before treatment and the effluent water quality performance data after treatment are measured daily. The water quality performance data include: ammonia nitrogen concentration, nitrite nitrogen concentration, nitrate nitrogen concentration and chemical oxygen demand. The concentration of ammonia nitrogen was determined by Nessler's reagent spectrophotometry. The principle is that ammonia nitrogen reacts with Nessler's reagent under alkaline conditions to form a yellow-brown complex. The absorbance was measured at a wavelength of 420 nm, and the absorbance was compared with a standard curve to obtain the concentration of ammonia nitrogen.

[0024] The concentration of nitrite nitrogen was determined by N-(1-naphthyl)-ethylenediamine spectrophotometry. The principle is that under acidic conditions, nitrite nitrogen undergoes a diazotization reaction with p-aminobenzenesulfonamide, and then couples with N-(1-naphthyl)-ethylenediamine hydrochloride to generate a red dye. The absorbance was measured at 540 nm, and the absorbance was compared with a standard curve to obtain the concentration of nitrite nitrogen.

[0025] The concentration of nitrate nitrogen was determined by ultraviolet spectrophotometry. The principle is that nitrate ions have strong absorption at a wavelength of 220 nm, while dissolved organic matter has absorption at 275 nm. The difference in absorbance at 220 nm and 275 nm was calculated and measured, and the concentration of nitrate nitrogen was obtained by referring to the standard curve.

[0026] The total nitrogen concentration in the influent is the sum of the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the influent on that day, and the total nitrogen concentration in the effluent is the sum of the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the effluent on that day; The total nitrogen removal rate for the day is obtained by dividing the difference between the total nitrogen concentration in the influent and the total nitrogen concentration in the effluent by the total nitrogen concentration in the influent. The nitrogen removal efficiency is obtained by multiplying the difference in total nitrogen concentration between the influent and effluent by the influent flow rate and then dividing by the reactor volume. The target total nitrogen removal rate and the range of change of total nitrogen removal rate are preset, and the detection time window is set; When the total nitrogen removal rate of each day within the detection time window is greater than or equal to the target total nitrogen removal rate, and the absolute difference between the total nitrogen removal rates of any two adjacent days within the detection time window does not exceed the range of change in total nitrogen removal rate, the continuous flow reactor is determined to have reached a steady state. The average total nitrogen removal rate and average nitrogen removal efficiency of each day within the detection time window are calculated as the total nitrogen removal rate and nitrogen removal rate after the continuous flow reactor has been operating stably.

[0027] The total nitrogen removal rate and nitrogen removal efficiency for each day were calculated separately. In the initial stage of operation of an autotrophic nitrogen removal system for urban wastewater, the functional microbial community needs to adapt to water quality, carrier structure, and environmental conditions. When the system is not yet stable, the nitrogen removal efficiency fluctuates significantly, and the measured efficiency at this time cannot reflect the system's true capacity. To ensure the representativeness of the total nitrogen removal rate and nitrogen removal efficiency of the continuous flow reactor, steady-state conditions need to be established to screen and calculate the total nitrogen removal rate and nitrogen removal efficiency. The steady-state conditions are based on three aspects: the biological metabolic characteristics of the autotrophic nitrogen removal system, the operating rules of the continuous flow reactor, and the feasibility of the engineering assessment. The following conditions are considered: Steady-state conditions are divided into absolute compliance conditions and fluctuation convergence conditions. The absolute compliance condition is that the total nitrogen removal rate of each day is greater than or equal to the target total nitrogen removal rate, ensuring that the system reaches an acceptable minimum nitrogen removal level in terms of performance, rather than stabilizing in an inefficient state. The fluctuation convergence condition is that the absolute difference between the total nitrogen removal rates of any two adjacent days does not exceed the total nitrogen removal rate change range. The fluctuation convergence condition is that the difference between the total nitrogen removal rates of any two consecutive days within the detection time window does not exceed the preset upper limit, i.e., the total nitrogen removal rate change range, to prevent short-term oscillations and ensure that the system has passed the state of numerical instability.

[0028] A higher target total nitrogen removal rate requires stricter denitrification performance and is suitable for scenarios with high discharge standards and stringent effluent quality requirements. A lower target total nitrogen removal rate requires more lenient denitrification performance and reflects that the evaluation focuses on stability rather than efficiency. A larger variation in the total nitrogen removal rate indicates a higher tolerance for data fluctuations, while a smaller variation in the total nitrogen removal rate indicates higher requirements for system stability and is suitable for precise evaluation scenarios. As an implementation method, those skilled in the art can set specific values ​​for the total nitrogen removal rate and the variation range of the total nitrogen removal rate according to the actual application scenario, which are not limited here.

[0029] Table 1 shows the changes in total nitrogen removal rate from the initial startup of the denitrification system until it reaches steady state. The target total nitrogen removal rate was set at 84%. Based on the daily total nitrogen removal rate, the entire process was divided into three stages according to the number of reaction days. Days 1 to 10 were the adaptation period, during which the total nitrogen removal rate only increased from 12.3% to 37.2%. This indicates that the two functional bacterial groups need time to adapt to the carrier microenvironment and establish preliminary metabolic activities. Due to their slow growth, the anaerobic ammonia oxidizing bacteria lagged behind the ammonia oxidizing bacteria in activity. Days 11 to 20 were the rapid improvement period, during which the removal rate increased from 43.8% to 82.7%. At this time, the nitrite nitrogen produced by the ammonia oxidizing bacteria began to be effectively utilized by the anaerobic ammonia oxidizing bacteria, forming a positive feedback loop through synergistic metabolism, with the rate increasing exponentially. Days 21 to 30 were the steady-state period, during which the total nitrogen removal rate fluctuated around 84.5%, and the generation and consumption of nitrite nitrogen reached a dynamic equilibrium, corresponding to the denitrification system reaching steady state.

[0030] Table 1. Changes in Total Nitrogen Removal Rate Step 3: Measure the ammonia oxidation rate of the outer aerobic layer and the anaerobic ammonia oxidation rate of the inner anaerobic layer of the embedded carrier respectively. Calculate the rate matching degree and matching deviation index based on the ammonia oxidation rate and the anaerobic ammonia oxidation rate. Determine the imbalance type of the denitrification system based on the matching deviation index. In this embodiment, the principle for determining the ammonia oxidation rate of the outer aerobic layer of the embedded carrier is as follows: a certain amount of double-layer embedded carrier is taken out from the continuous flow reactor, the outer aerobic layer is separated, and it is placed under aerobic conditions. Simulated wastewater with a known ammonia nitrogen concentration is added, and the reaction conditions are controlled to be consistent with those of the reactor. The ammonia nitrogen concentration of the simulated wastewater is measured at intervals. The ammonia oxidation rate is obtained by dividing the ammonia nitrogen concentration difference over a period of time by the length of that period.

[0031] The principle for determining the anaerobic ammonia oxidation rate of the inner anaerobic layer of the embedded carrier is as follows: a certain amount of double-layer embedded carrier is taken out from the continuous flow reactor, the inner anaerobic layer is separated, and it is placed under anaerobic conditions. Simulated wastewater containing nitrite nitrogen is added, and the reaction conditions are controlled to be consistent with those of the reactor. The concentration of nitrite nitrogen in the simulated wastewater is measured at intervals. The anaerobic ammonia oxidation rate is obtained by dividing the difference in nitrite nitrogen concentration over a period of time by the length of that period.

[0032] In this embodiment, the rate matching degree and matching deviation index are calculated based on the ammonia oxidation rate and the anaerobic ammonia oxidation rate. The principle for determining the imbalance type of the denitrification system based on the matching deviation index is as follows: Divide the ammonia oxidation rate of the day by the anaerobic ammonia oxidation rate to obtain the rate matching degree of the day; The optimal rate matching degree is preset. The matching deviation index for the day is obtained by dividing the rate matching degree of the day by the optimal rate matching degree and then taking the natural logarithm. The matching deviation index is calculated using the following formula: in, This indicates the matching deviation index for the day. This indicates the rate matching degree for the day. Indicates the optimal rate matching degree. This indicates the ammonia oxidation rate for that day. This indicates the anaerobic ammonium oxidation rate for that day; The optimal rate matching degree represents the ideal ratio that the ammonia oxidation rate of the outer layer of ammonia oxidizing bacteria and the anaerobic ammonia oxidation rate of the inner layer of anaerobic ammonia oxidizing bacteria should satisfy when the denitrification system achieves the best denitrification effect. Ideally, for every part of ammonia nitrogen oxidized by ammonia oxidizing bacteria, one part of nitrite nitrogen is produced. Anaerobic ammonia oxidizing bacteria consume this part of nitrite nitrogen and one part of ammonia nitrogen to generate nitrogen gas. At this time, the ammonia oxidation rate and the anaerobic ammonia oxidation rate are equal, and the corresponding rate matching degree is the optimal rate matching degree, which is 1.

[0033] The matching deviation index reflects the degree to which the actual metabolic rate deviates from the ideal cooperative state between the outer layer of ammonia-oxidizing bacteria and the inner layer of anaerobic ammonia-oxidizing bacteria in a denitrification system. When the ammonia oxidation rate and the anaerobic ammonia oxidation rate are exactly stoichiometric, the rate matching degree is equal to the optimal rate matching degree, and the denitrification system is in the optimal synergistic state. When the reaction rates of the inner and outer layers are mismatched, the ammonia oxidation rate is greater than the anaerobic ammonia oxidation rate, and the rate matching degree is greater than the optimal rate matching degree. This indicates a mismatch in reaction rates between the inner and outer layers, with the anaerobic ammonium oxidation rate exceeding the ammonium oxidation rate, resulting in a rate match less than the optimal rate match. This is difficult to achieve under actual operating conditions. Strictly equal to 0, therefore Small intervals approaching 0 are uniformly defined as unbalanced intervals, and the system is considered to be in an optimal matching state within this range.

[0034] When calculating the matching deviation index, the quotient is calculated first, followed by the logarithm. The quotient is used to ensure comparisons are made under the same dimensions, while the logarithm is taken because excessively rapid ammonia oxidation rates and excessively rapid anaerobic ammonia oxidation rates exhibit symmetry sensitivity. This indicates that the ammonia oxidation rate is too fast. This indicates that the anaerobic ammonium oxidation rate is too fast. The distribution is symmetrical with 0 as the center, which facilitates the subsequent unified setting of the imbalance threshold.

[0035] A first imbalance threshold and a second imbalance threshold are set, wherein the first imbalance threshold is less than the second imbalance threshold, and the respective activity thresholds for ammonia oxidation rate and anaerobic ammonia oxidation rate are preset. Three imbalance types are distinguished based on the first imbalance threshold, the second imbalance threshold, the activity threshold of ammonia oxidation rate, and the activity threshold of anaerobic ammonia oxidation rate. The three imbalance types include ammonia oxidation relatively over-rate type, anaerobic ammonia oxidation relatively over-rate type, and bidirectional activity deficiency type. If the ammonia oxidation rate is less than the activity threshold of the ammonia oxidation rate, and the anaerobic ammonia oxidation rate is less than the activity threshold of the anaerobic ammonia oxidation rate, the imbalance type is determined to be a bidirectional activity deficiency type. Provided that the ammonia oxidation rate is greater than or equal to the activity threshold of the ammonia oxidation rate and the anaerobic ammonia oxidation rate is greater than or equal to the activity threshold of the anaerobic ammonia oxidation rate, if the matching deviation index is greater than the second imbalance threshold, the imbalance type is judged to be the ammonia oxidation relative overrate type. If the matching deviation index is less than the first imbalance threshold, the imbalance type is determined to be anaerobic ammonia oxidation relative overrate type. If the matching deviation index is between the first imbalance threshold and the second imbalance threshold, the denitrification system is not imbalanced.

[0036] The value of is symmetrical on both sides of 0, with its positive and negative values ​​representing mismatches between the two reaction rates. In a nitrogen removal system, the ratio of ammonia oxidation rate to anaerobic ammonia oxidation rate is between 0.7 and 1.3, and the nitrogen removal system can still maintain a stable nitrogen removal effect. The values ​​corresponding to ammonia oxidation rate to anaerobic ammonia oxidation rate ratios of 0.7 and 1.3 are calculated respectively. The values ​​are -0.36 and 0.26. In summary, we take... As the boundary between imbalance and non-imbalance; When the ratio of ammonia oxidation rate to anaerobic ammonia oxidation rate exceeds 2 or falls below 0.5, nitrite accumulation or starvation of anaerobic ammonia oxidizing bacteria occurs in the denitrification system, significantly reducing denitrification efficiency. The calculations for the ratios of ammonia oxidation rate to anaerobic ammonia oxidation rate of 2 and 0.2 correspond to... The values ​​are 0.69 and -0.69. In summary, we take... As a boundary of severe imbalance.

[0037] A first imbalance threshold less than 0 indicates that the anaerobic ammonia oxidation rate is relatively too fast, and a second imbalance threshold greater than 0 indicates that the ammonia oxidation rate is relatively too fast. As one implementation, the range of the first imbalance threshold is... The range of the second imbalance threshold is: .

[0038] Under the premise that the bacterial community activity meets the standard, the matching deviation index is compared with the first imbalance threshold and the second imbalance threshold respectively. When the matching deviation index is greater than the second imbalance threshold, it indicates that the ammonia oxidation rate is significantly greater than the anaerobic ammonia oxidation rate. The ammonia oxidation rate is too fast, and the nitrite nitrogen produced in the outer layer cannot be consumed by the inner anaerobic ammonia oxidizing bacteria in time, resulting in an imbalance. The main reason for the imbalance is the excessively fast ammonia oxidation rate. At this time, the imbalance type is the ammonia oxidation relatively too fast type.

[0039] When the matching deviation index is less than the first imbalance threshold, it indicates that the anaerobic ammonia oxidation rate is significantly greater than the ammonia oxidation rate. The nitrite nitrogen provided by the outer layer is insufficient to meet the needs of the inner anaerobic ammonia oxidizing bacteria, and the anaerobic ammonia oxidation reaction cannot be fully utilized, resulting in an imbalance. The reason for the imbalance is that the anaerobic ammonia oxidation reaction cannot be fully utilized, and the ammonia oxidation rate is relatively too low. At this time, the imbalance type is the anaerobic ammonia oxidation relatively too fast type.

[0040] When the matching deviation index is between the first imbalance threshold and the second imbalance threshold, although there is a difference between the ammonia oxidation rate and the anaerobic ammonia oxidation rate, the deviation is not large and will not lead to obvious accumulation of nitrite nitrogen or starvation of anaerobic ammonia oxidizing bacteria. This is considered to be an unbalanced state.

[0041] The dual-activity deficiency type indicates that both the inner and outer bacterial communities are inactive, and in this case, the denitrification efficiency of the system is mainly related to the activity of the bacterial communities. The activity thresholds for ammonia oxidation rate and anaerobic ammonia oxidation rate are used to determine whether ammonia-oxidizing bacteria and anaerobic ammonia-oxidizing bacteria are in a state of insufficient activity. When the denitrification system reaches a steady state and is not in an unbalanced state, the ammonia oxidation rate and anaerobic ammonia oxidation rate are measured for 5 consecutive days, and the lower limit of their respective measured values ​​is taken as the activity thresholds for ammonia oxidation rate and anaerobic ammonia oxidation rate, respectively.

[0042] Step 4: Measure the actual structural parameters of the embedding carrier, retrieve the baseline values ​​of each structural parameter under normal system operation, and calculate the contribution of each structural parameter in the denitrification system to the matching deviation index under different imbalance types. In this embodiment, the principle for calculating the contribution of each structural parameter to the matching deviation index under different imbalance types is as follows: The measured structural parameters of the embedded carrier include the measured values ​​of porosity and the measured values ​​of the inner and outer layer thickness ratio; The principle for obtaining the measured porosity value is as follows: a certain number of double-layer embedded carriers are taken out from the continuous flow reactor, and the total volume of the taken double-layer embedded carriers is determined by the water displacement method; after drying the double-layer embedded carriers, the volume of the carrier solid material is determined by the specific gravity bottle method, and the measured porosity value is obtained by subtracting the volume of the carrier solid material from the total volume and then dividing by the total volume.

[0043] The principle for obtaining the measured value of the inner-outer layer thickness ratio is as follows: A certain number of bilayer embedded carriers are taken out from the continuous flow reactor. For each bilayer embedded carrier, after resin embedding, frozen sections are obtained to obtain cross-sectional thin sections of the bilayer embedded carrier. The outer layer thickness from the outer surface to the interface between the inner and outer layers is observed and measured using an electron microscope, and the inner layer thickness from the interface between the inner and outer layers to the center of the carrier is compared with the outer layer thickness. The inner layer thickness is divided by the outer layer thickness to obtain the inner-outer layer thickness ratio of each bilayer embedded carrier. The average value of the inner-outer layer thickness ratio of all the taken bilayer embedded carriers is calculated to obtain the measured value of the inner-outer layer thickness ratio.

[0044] Obtain the baseline values ​​of porosity and inner / outer layer thickness ratio when the denitrification system is in normal operating condition; The porosity deviation rate is obtained by subtracting the porosity reference value from the measured porosity value, taking the absolute value, and then dividing it by the porosity reference value. The deviation rate of the inner and outer layer thickness ratio is obtained by subtracting the reference value of the inner and outer layer thickness ratio from the measured value and then dividing the absolute value by the reference value of the inner and outer layer thickness ratio. Based on the imbalance type of the denitrification system, preset porosity influence coefficient and inner and outer layer thickness ratio influence coefficient are used. The contribution of porosity to the matching deviation index is calculated by multiplying the porosity influence coefficient by the porosity deviation rate. The contribution of the inner and outer layer thickness ratio to the matching deviation index is calculated by multiplying the inner and outer layer thickness ratio influence coefficient by the inner and outer layer thickness ratio deviation rate.

[0045] "The denitrification system is in normal operation" means that the denitrification system is in an unbalanced state. After the denitrification system reaches a steady state, the porosity and the ratio of inner and outer layer thickness of the denitrification system are collected for several consecutive days. The average values ​​of the porosity and the ratio of inner and outer layer thickness collected over several days are calculated and used as the benchmark values ​​of porosity and the ratio of inner and outer layer thickness, respectively. "Collected for several consecutive days" means at least five days.

[0046] The formula for calculating the contribution of porosity to the matching deviation index is: in, This indicates the contribution of porosity to the matching deviation index. This represents the measured value of porosity. Indicates the baseline value of porosity. Indicates the porosity deviation rate. Indicates the porosity influence coefficient; The contribution of porosity to the matching deviation index reflects the relative deviation between the actual and reference values ​​of porosity in the embedded carrier structure, and to what extent it leads to the mismatch in metabolic rates among the denitrifying bacterial communities in the system. Porosity affects the diffusion efficiency of substances (such as ammonia nitrogen, nitrite nitrogen, and dissolved oxygen) inside the carrier. The higher the porosity, the lower the mass transfer resistance, and the easier it is for nitrite nitrogen produced by the outer ammonia-oxidizing bacteria to enter the inner anaerobic zone. The lower the porosity, the more obstructed the mass transfer, leading to starvation of the inner anaerobic ammonia-oxidizing bacteria or accumulation of nitrite nitrogen in the outer layer. Different denitrification systems have different porosity reference values, so the porosity deviation rate is calculated to eliminate dimensional and system differences.

[0047] The degree of influence of porosity varies under different types of imbalance. The range of values ​​is The larger the value, the greater the impact of porosity on system imbalance, and mass transfer is the main limiting factor for the current imbalance. The smaller the porosity, the less impact the porosity deviation has on system imbalance, and the main cause of imbalance is not mass transfer. For the relatively over-rate ammonia oxidation type, the outer layer ammonia oxidation rate is too fast, producing a large amount of nitrite nitrogen, but the inner layer anaerobic ammonia oxidizing bacteria cannot consume it in time. If the porosity is too low, mass transfer is hindered, and nitrite nitrogen is even more difficult to enter the inner layer, exacerbating its accumulation. The matching deviation index rises rapidly, and the impact of porosity is significant. Therefore, the porosity influence coefficient is relatively large for the relatively over-rate ammonia oxidation type. For the relatively over-rate anaerobic ammonia oxidation type, the inner layer anaerobic ammonia oxidation rate is too fast. When the supply of nitrite nitrogen in the outer layer is insufficient, even if the porosity is small and mass transfer is hindered, the supply of nitrite nitrogen is already low, so the impact of the hindered mass transfer is relatively limited. Even if the porosity is large, it cannot increase the yield of nitrite nitrogen in the outer layer. In this case, the influence of porosity is relatively weak, and the value of the porosity influence coefficient is lower than that in the relatively rapid ammonia oxidation type. For the dual-activity insufficient type, the main reason is the activity of bacteria in the inner and outer layers, which is weakly related to porosity. The deviation in porosity has almost no impact on the already extremely low metabolic compatibility. Therefore, the porosity influence coefficient is the lowest in this case.

[0048] As one implementation method, when the imbalance type is ammonia oxidation relatively over-rate, The range of values ​​is When the imbalance type is anaerobic ammonium oxidation with a relative overrate, The range of values ​​is When the imbalance type is bidirectional insufficiency, The range of values ​​is The specific value is to be set by those skilled in the art based on the actual situation, and is not limited here.

[0049] The formula for calculating the contribution of the inner and outer layer thickness ratio to the matching deviation index is as follows: in, This indicates the contribution of the inner and outer layer thickness ratio to the matching deviation index. This indicates the measured value of the ratio of the inner and outer layer thicknesses. This indicates the ratio of the inner and outer layer thicknesses to a reference value. This indicates the deviation rate of the thickness ratio between the inner and outer layers. Indicates the influence coefficient of the inner and outer layer thickness ratio; The inner-outer layer thickness ratio represents the ratio of the inner layer thickness to the outer layer thickness. Its contribution to the matching deviation index reflects the extent to which the actual inner-outer layer thickness ratio deviates from the baseline value under normal operating conditions, leading to a mismatch in reaction rates between ammonia-oxidizing bacteria and anaerobic ammonia-oxidizing bacteria in the system. The inner-outer layer thickness ratio determines the path length for nitrite nitrogen transfer from the outer layer to the inner layer and the proportion of reaction space for anaerobic ammonia-oxidizing bacteria in the inner layer. A larger inner-outer layer thickness ratio indicates a relatively thicker inner layer and a relatively thinner outer layer, resulting in a smaller proportion of space for ammonia-oxidizing bacteria in the outer layer, limiting the ammonia oxidation rate and reducing the production of nitrite nitrogen. A larger proportion of space for anaerobic ammonia-oxidizing bacteria in the inner layer leads to a faster reaction rate, making a relative over-acceleration imbalance of anaerobic ammonia oxidation bacteria more likely. Conversely, a smaller inner-outer layer thickness ratio indicates a relatively thinner inner layer and a relatively thicker outer layer, resulting in a larger outer layer space, a higher nitrite nitrogen generation rate, and a smaller inner layer space, limiting the total amount of anaerobic ammonia-oxidizing bacteria and their ability to consume nitrite nitrogen, making an over-acceleration imbalance of ammonia oxidation more likely.

[0050] The deviation rate of the inner and outer layer thickness ratio reflects the degree to which the current inner and outer layer thickness ratio deviates from the reference value. The larger the deviation rate of the inner and outer layer thickness ratio, the more serious the deviation of the spatial structure of the current embedding carrier from the normal operating state, which leads to a decrease in the spatial coupling efficiency between the production and consumption of nitrite nitrogen and the disruption of the synergistic work among the microbial community.

[0051] The influence coefficient of the inner-outer layer thickness ratio is used to measure the extent to which the deviation of the inner-outer layer thickness ratio from the benchmark value has led to the current metabolic matching deviation. For the ammonia oxidation over-acceleration type imbalance, the inner-outer layer thickness ratio directly determines the relative relationship between the outer layer's nitrite production capacity and the inner layer's consumption capacity. A small inner-outer layer thickness ratio is one of the core structural causes of this type of imbalance. When the outer layer is thicker, the diffusion path of nitrite nitrogen from the outer layer to the inner layer is longer. Even if it is produced, it is difficult to reach the inner layer quickly, which aggravates the local accumulation of nitrite nitrogen. In this type of imbalance, the deviation rate of the inner-outer layer thickness ratio has a direct and significant impact on the matching deviation index. Therefore, the value of the inner-outer layer thickness ratio influence coefficient is relatively large. For the anaerobic ammonium oxidation over-rate imbalance, the excessively large inner-outer layer thickness ratio is a secondary cause of the imbalance. The main reason is the insufficient nitrite nitrogen produced by the outer layer. Simply increasing the inner layer thickness will not significantly worsen the reaction process. Therefore, the influence coefficient of the inner-outer layer thickness ratio is moderate under this type of imbalance. For the bidirectional inactivity-deficient imbalance, the main cause of the imbalance is the insufficient activity of the microbial community. The influence of structure is covered by activity. Therefore, the influence of the inner-outer layer thickness ratio on this type of imbalance is weak, and the influence coefficient of the inner-outer layer thickness ratio is the lowest.

[0052] As one implementation method, in an ammonia oxidation-over-rate imbalance The range of values ​​is In the anaerobic ammonium oxidation overrate imbalance The range of values ​​is In the bidirectional activity deficiency type of imbalance The range of values ​​is The specific value is determined by those skilled in the art based on the time situation, and is not limited here.

[0053] Step 5: Generate a basic score for denitrification efficiency based on the total nitrogen removal rate and nitrogen removal efficiency. Determine the mismatch penalty factor by combining the contribution of each structural parameter. Calculate the denitrification efficiency index based on the basic score and the mismatch penalty factor. Judge the denitrification effect of the system by using the denitrification efficiency index.

[0054] In this embodiment, the principle for generating the basic score for denitrification efficiency based on total nitrogen removal rate and nitrogen removal efficiency is as follows: The total nitrogen removal rate and nitrogen removal efficiency were normalized separately. The normalized total nitrogen removal rate and normalized nitrogen removal efficiency were then weighted and summed to obtain the basic score for nitrogen removal efficiency. The weight of the normalized total nitrogen removal rate was lower than that of the normalized nitrogen removal efficiency, and the sum of the two weights was 1. The formula for the basic score for nitrogen removal efficiency is as follows: in, This represents the basic score for denitrification efficiency. This represents the normalized total nitrogen removal rate. This represents the normalized nitrogen removal efficiency. These represent the weights of the normalized total nitrogen removal rate and the normalized nitrogen removal efficiency, respectively. The basic denitrification efficiency score reflects the comprehensive denitrification capacity of an urban wastewater autotrophic denitrification system under steady-state operation. A higher score indicates better total nitrogen removal and higher efficiency. Total nitrogen removal rate measures the treatment outcome, reflecting the system's thoroughness in removing pollutants. Even with a slow treatment speed, a high removal rate can be achieved given sufficient time. This is a static efficiency indicator. Nitrogen removal efficiency measures treatment capacity, reflecting the system's production efficiency and treatment load. Even with a low removal rate, a large flow rate allows the system to remove significant amounts of nitrogen daily, making it a dynamic rate indicator. Considering only a single indicator is insufficient. A system with a high total nitrogen removal rate but extremely low nitrogen removal efficiency lacks engineering application value. Similarly, a system with high nitrogen removal efficiency but a low total nitrogen removal rate indicates inefficient emissions and lacks engineering application value.

[0055] The basic score for denitrification efficiency is calculated by weighted summation of total nitrogen removal rate and nitrogen removal efficiency. These two indicators are independent, ensuring that their contributions to the basic score are considered simultaneously, thus avoiding the negative impact of a single, low-value indicator on the overall denitrification efficiency score. Autotrophic denitrification systems pursue low-carbon, low-cost processes. Nitrogen removal efficiency directly reflects the actual processing capacity per unit reactor volume and is key to assessing whether the system fully leverages the advantages of autotrophic denitrification. While total nitrogen removal rate is also important, further improvements after reaching a baseline value have marginal benefits, resulting in limited gains. Increasing the nitrogen removal rate, however, directly leads to practical benefits such as reactor miniaturization and energy savings. Therefore, the weight of normalized nitrogen removal efficiency is greater than that of normalized total nitrogen removal rate.

[0056] As one implementation method, The range of values ​​is , The range of values ​​is The specific values ​​are to be set by those skilled in the art based on the actual situation, and are not limited here.

[0057] The mismatch penalty factor is generated by combining the contribution of each structural parameter. The principle is as follows: The contribution of porosity to the matching deviation index and the contribution of the inner and outer layer thickness ratio to the matching deviation index are summed, and the minimum value between the summation result and value 1 is taken as the mismatch penalty factor.

[0058] The mismatch penalty factor reflects the degree to which the mismatch of the carrier's microstructure disrupts the synergistic metabolic capacity of the denitrification system. The contributions of porosity and the inner-outer layer thickness ratio to the mismatch index are relatively independent. If the porosity is too low and the outer layer is too thick, the rate of increase in the mismatch index is much greater than that of a single factor. Therefore, the contributions of porosity and the inner-outer layer thickness ratio to the mismatch index are summed to obtain the overall impact of the carrier structure on the denitrification system. The upper limit is set to 1 to ensure that the subsequent calculation of the denitrification efficiency index is not negative (the minimum denitrification efficiency is 0, and it will not be reduced to a negative value).

[0059] The denitrification efficiency index is calculated based on the denitrification efficiency baseline score and the mismatch penalty factor. The principle of judging the denitrification effect of the system through the denitrification efficiency index is as follows: The adjustment factor is obtained by subtracting the mismatch penalty factor from 1, and the denitrification efficiency index is obtained by multiplying the adjustment factor by the denitrification efficiency base score. The denitrification efficiency index reflects the comprehensive denitrification efficiency level of an urban wastewater autotrophic denitrification system after comprehensively considering both macroscopic denitrification effect and microscopic structural mismatch. Macroscopic denitrification capacity represents the basic denitrification efficiency score, reflecting the efficiency and amount of nitrogen removal under steady-state operation. The influence of the carrier's microstructure on the matching deviation index is quantified by the porosity deviation rate and the inner-outer layer thickness ratio deviation rate. A mismatch penalty factor is subtracted from 1 as a reduction coefficient for the basic denitrification efficiency score. A larger structural deviation results in a larger mismatch penalty factor, and a smaller basic denitrification efficiency score leads to a lower denitrification efficiency index; conversely, a smaller structural deviation results in a smaller mismatch penalty factor, and a larger basic denitrification efficiency score leads to a higher denitrification efficiency index.

[0060] Set a first evaluation threshold and a second evaluation threshold, wherein the first evaluation threshold is less than the second evaluation threshold; If the denitrification efficiency index is greater than or equal to the second evaluation threshold, it indicates that the denitrification efficiency of the urban sewage autotrophic denitrification system is excellent. If the denitrification efficiency index is less than the first evaluation threshold, it indicates that the denitrification efficiency of the urban sewage autotrophic denitrification system is poor. If the denitrification efficiency index is between the first evaluation threshold and the second evaluation threshold, it indicates that the denitrification efficiency of the urban wastewater autotrophic denitrification system is moderate.

[0061] In practical applications, to ensure the denitrification system reaches a steady state without imbalance, denitrification efficiency indices are continuously collected over multiple days. The mean and standard deviation of these indices are calculated, and the mean is subtracted from the standard deviation. The first evaluation threshold is calculated by multiplying the mean by the standard deviation, representing a boundary value where the nitrogen removal capacity is below average but still acceptable. The second evaluation threshold is obtained by multiplying the value by a factor of 1, representing a performance with nitrogen removal capacity above average; among which... The range of values ​​is , The range of values ​​is The specific values ​​are to be set by those skilled in the art based on the actual situation, and are not limited here.

[0062] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0063] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0064] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0065] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for determining the denitrification efficiency of a functional bacterial community in an urban wastewater autotrophic denitrification system, characterized by, The specific steps include: Step 1: Prepare an embedded carrier consisting of a double-layer structure of an outer aerobic layer and an inner anaerobic layer, and establish a continuous flow reactor; Step 2: Collect influent and effluent samples from the continuous flow reactor and measure the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen to calculate the total nitrogen removal rate and nitrogen removal rate after the continuous flow reactor has been operating stably. Step 3: Measure the ammonia oxidation rate of the outer aerobic layer and the anaerobic ammonia oxidation rate of the inner anaerobic layer of the embedded carrier respectively. Calculate the rate matching degree and matching deviation index based on the ammonia oxidation rate and the anaerobic ammonia oxidation rate. Determine the imbalance type of the denitrification system based on the matching deviation index. Step 4: Measure the actual structural parameters of the embedding carrier, retrieve the baseline values ​​of each structural parameter under normal system operation, and calculate the contribution of each structural parameter in the denitrification system to the matching deviation index under different imbalance types. Step 5: Generate a basic score for denitrification efficiency based on total nitrogen removal rate and nitrogen removal efficiency. Determine the mismatch penalty factor by combining the contribution of each structural parameter. Calculate the denitrification efficiency index based on the basic score for denitrification efficiency and the mismatch penalty factor. Judge the denitrification effect of the system by the denitrification efficiency index. The principle for calculating the contribution of each structural parameter to the matching deviation index under different imbalance types is as follows: The measured structural parameters of the embedded carrier include the measured values ​​of porosity and the measured values ​​of the inner and outer layer thickness ratio; Obtain the baseline values ​​of porosity and inner / outer layer thickness ratio when the denitrification system is in normal operating condition; The porosity deviation rate is obtained by subtracting the porosity reference value from the measured porosity value, taking the absolute value, and then dividing it by the porosity reference value. The deviation rate of the inner and outer layer thickness ratio is obtained by subtracting the reference value of the inner and outer layer thickness ratio from the measured value and then dividing the absolute value by the reference value of the inner and outer layer thickness ratio. Based on the imbalance type of the denitrification system, preset porosity influence coefficient and inner and outer layer thickness ratio influence coefficient are used. The contribution of porosity to the matching deviation index is calculated by multiplying the porosity influence coefficient by the porosity deviation rate. The contribution of the inner and outer layer thickness ratio to the matching deviation index is calculated by multiplying the inner and outer layer thickness ratio influence coefficient by the inner and outer layer thickness ratio deviation rate. The principle for generating a basic score for denitrification efficiency based on total nitrogen removal rate and nitrogen removal efficiency is as follows: The total nitrogen removal rate and nitrogen removal efficiency are normalized separately. The normalized total nitrogen removal rate and normalized nitrogen removal efficiency are then weighted and summed to obtain the basic score of nitrogen removal efficiency. The weight of the normalized total nitrogen removal rate is lower than that of the normalized nitrogen removal efficiency, and the sum of the two weights is 1. The mismatch penalty factor is generated by combining the contribution of each structural parameter. The principle is as follows: The contribution of porosity to the matching deviation index and the contribution of the inner and outer layer thickness ratio to the matching deviation index are summed, and the minimum value between the summation result and value 1 is taken as the mismatch penalty factor.

2. The method according to claim 1, wherein the method is characterized by: The principle for preparing an embedded carrier consisting of a double-layer structure with an outer aerobic layer and an inner anaerobic layer, and establishing a continuous flow reactor, is as follows: A polyvinyl alcohol solution was mixed with an anaerobic ammonia-oxidizing bacteria solution to obtain a polyvinyl alcohol-anaerobic ammonia-oxidizing bacteria mixture. The mixture was added dropwise to a boric acid solution to initiate the first cross-linking process, forming preliminary carrier particles. A polyvinyl alcohol solution was mixed with an ammonia-oxidizing bacteria solution to obtain a polyvinyl alcohol-ammonia-oxidizing bacteria mixture. The initial carrier particles are immersed in a polyvinyl alcohol-ammonia oxidizing bacteria mixture to coat the outer layer of the particles with the ammonia oxidizing bacteria solution. Then, the coated carrier particles are immersed in a boric acid solution for a second cross-linking, forming a double-layered embedded carrier with an outer layer enriched with ammonia oxidizing bacteria and an inner layer enriched with anaerobic ammonia oxidizing bacteria. A continuous flow reactor was constructed using conventional processes, and an initial filling rate was preset. The prepared embedding carrier was then added into the continuous flow reactor according to the initial filling rate.

3. The method according to claim 1, wherein the method is characterized by: The principle for calculating the total nitrogen removal rate and nitrogen removal percentage after a continuous flow reactor has been operating stably is as follows: The wastewater to be treated is pumped into a continuous flow reactor. The influent water quality performance data before treatment and the effluent water quality performance data after treatment are measured daily. The water quality performance data include: ammonia nitrogen concentration, nitrite nitrogen concentration, nitrate nitrogen concentration and chemical oxygen demand. The total nitrogen concentration in the influent is the sum of the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the influent on that day, and the total nitrogen concentration in the effluent is the sum of the concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the effluent on that day; The total nitrogen removal rate for the day is obtained by dividing the difference between the total nitrogen concentration in the influent and the total nitrogen concentration in the effluent by the total nitrogen concentration in the influent. The nitrogen removal efficiency is obtained by multiplying the difference in total nitrogen concentration between the influent and effluent by the influent flow rate and then dividing by the reactor volume. The target total nitrogen removal rate and the range of change of total nitrogen removal rate are preset, and the detection time window is set; When the total nitrogen removal rate of each day within the detection time window is greater than or equal to the target total nitrogen removal rate, and the absolute difference between the total nitrogen removal rates of any two adjacent days within the detection time window does not exceed the range of change in total nitrogen removal rate, the continuous flow reactor is determined to have reached a steady state. The average total nitrogen removal rate and average nitrogen removal efficiency of each day within the detection time window are calculated as the total nitrogen removal rate and nitrogen removal rate after the continuous flow reactor has been operating stably.

4. The method according to claim 1, wherein the method is characterized by: The principle for calculating the rate matching degree and matching deviation index based on the ammonia oxidation rate and the anaerobic ammonia oxidation rate, and determining the imbalance type of the denitrification system based on the matching deviation index, is as follows: Divide the ammonia oxidation rate of the day by the anaerobic ammonia oxidation rate to obtain the rate matching degree of the day; The optimal rate matching degree is preset, and the matching deviation index for the day is obtained by dividing the rate matching degree of the day by the optimal rate matching degree and then taking the natural logarithm. A first imbalance threshold and a second imbalance threshold are set, wherein the first imbalance threshold is less than the second imbalance threshold, and the respective activity thresholds for ammonia oxidation rate and anaerobic ammonia oxidation rate are preset. Three imbalance types are distinguished based on the first imbalance threshold, the second imbalance threshold, the activity threshold of ammonia oxidation rate, and the activity threshold of anaerobic ammonia oxidation rate. The three imbalance types include ammonia oxidation relatively over-rate type, anaerobic ammonia oxidation relatively over-rate type, and bidirectional activity deficiency type. If the ammonia oxidation rate is less than the activity threshold of the ammonia oxidation rate, and the anaerobic ammonia oxidation rate is less than the activity threshold of the anaerobic ammonia oxidation rate, the imbalance type is determined to be a bidirectional activity deficiency type. Provided that the ammonia oxidation rate is greater than or equal to the activity threshold of the ammonia oxidation rate and the anaerobic ammonia oxidation rate is greater than or equal to the activity threshold of the anaerobic ammonia oxidation rate, if the matching deviation index is greater than the second imbalance threshold, the imbalance type is judged to be the ammonia oxidation relative overrate type. If the matching deviation index is less than the first imbalance threshold, the imbalance type is determined to be anaerobic ammonia oxidation relative overrate type. If the matching deviation index is between the first imbalance threshold and the second imbalance threshold, the denitrification system is not imbalanced.

5. The method according to claim 1, wherein the method is characterized by: The denitrification efficiency index is calculated based on the denitrification efficiency baseline score and the mismatch penalty factor. The principle of judging the denitrification effect of the system through the denitrification efficiency index is as follows: The adjustment factor is obtained by subtracting the mismatch penalty factor from 1, and the denitrification efficiency index is obtained by multiplying the adjustment factor by the denitrification efficiency base score. Set a first evaluation threshold and a second evaluation threshold, wherein the first evaluation threshold is less than the second evaluation threshold; If the denitrification efficiency index is greater than or equal to the second evaluation threshold, it indicates that the denitrification efficiency of the urban sewage autotrophic denitrification system is excellent. If the denitrification efficiency index is less than the first evaluation threshold, it indicates that the denitrification efficiency of the urban sewage autotrophic denitrification system is poor. If the denitrification efficiency index is between the first evaluation threshold and the second evaluation threshold, it indicates that the denitrification efficiency of the urban wastewater autotrophic denitrification system is moderate.

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