Control method for adding carbon source for sewage treatment

Abstract

The invention provides a sewage treatment carbon source adding control method, and relates to the technical field of sewage treatment, and the method comprises the following steps: obtaining water inlet parameters of a water inlet end of sewage to be treated and process parameters of a treatment section, the water inlet parameters comprising chemical oxygen demand, total nitrogen, total phosphorus and flow; the process parameters comprise the phosphate concentration at the tail end of an anaerobic tank, the nitrate concentration at the tail end of an anoxic tank, and the total nitrogen and chemical oxygen demand of inlet water of a denitrification filter tank; dynamically calculating a predicted carbon-nitrogen ratio and a predicted carbon-phosphorus ratio in real time according to water inlet parameters and the process parameters; based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and a preset effluent quality standard, a carbon source adding point and a first carbon source adding amount are determined, and the carbon source adding point comprises at least one of an anaerobic tank, an anoxic tank and a denitrification filter tank; according to the carbon source feeding point and the first carbon source feeding amount, the carbon source feeding device is controlled to execute corresponding feeding operation, through segmented feeding and closed-loop control, COD standard exceeding caused by excessive carbon sources is avoided, and secondary pollution is effectively inhibited.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and specifically relates to a control method for carbon source dosing in sewage treatment. Background Art

[0002] In the field of sewage treatment, biological nitrogen and phosphorus removal is one of the core processes, and its efficiency highly depends on the reasonable dosing of carbon sources. Previously, the industry generally adopted the following control method of dosing carbon sources in a fixed ratio (dosing according to the fixed carbon-nitrogen ratio (C / N) and carbon-phosphorus ratio (C / P) set by experience), lacking the dynamic response ability to fluctuations in influent water quality; With technological progress, in the prior art, attempts have been made to perform dynamic response according to influent water quality and adopt a dynamic dosing method. For example, the invention patent with the publication number CN117892970A proposes a carbon source intelligent dosing method, system and storage medium, which can solve the problem of easy over-dosing when the influent water quality fluctuates, resulting in an increase in effluent COD. However, it only doses for the denitrification filter, ignoring the carbon source requirements of the anaerobic tank (phosphorus release) and the anoxic tank (denitrification), resulting in low phosphorus removal efficiency or unreasonable carbon source distribution. Summary of the Invention

[0003] In view of the above defects or deficiencies in the prior art, the present application aims to provide a control method for carbon source dosing in sewage treatment to ensure reasonable distribution of carbon sources and improve phosphorus removal efficiency; the control method includes the following steps: Obtain the influent parameters at the influent end of the sewage to be treated, where the influent parameters include chemical oxygen demand, total nitrogen, total phosphorus and flow rate; Real-time monitor the process parameters of the treatment section, where the process parameters include the phosphate concentration at the end of the anaerobic tank, the nitrate concentration at the end of the anoxic tank, the total nitrogen and chemical oxygen demand at the inlet of the denitrification filter; Dynamically calculate the predicted carbon-nitrogen ratio and the predicted carbon-phosphorus ratio in real time according to the influent parameters and the process parameters; Based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard, determine the carbon source dosing point and the first carbon source dosing amount, where the carbon source dosing point includes at least one of the anaerobic tank, the anoxic tank and the denitrification filter; According to the carbon source dosing point and the first carbon source dosing amount, control the carbon source dosing device to perform the corresponding dosing operation.

[0004] According to the technical solution provided by the present application, the step of determining the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard includes the following steps: If the predicted carbon-to-phosphorus ratio at the inlet end is less than 15, the anaerobic tank is taken as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-to-phosphorus ratio to the target carbon-to-phosphorus ratio; the target carbon-to-phosphorus ratio is dynamically adjusted within a first preset range; If the nitrate concentration at the end of the anoxic tank is greater than 2.5 mg / L or the predicted carbon-to-nitrogen ratio at the inlet end is less than 4, the anoxic tank is taken as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-to-nitrogen ratio to the target carbon-to-nitrogen ratio; the target carbon-to-nitrogen ratio is dynamically adjusted within a second preset range; If the total nitrogen in the influent of the denitrification filter is greater than 15 mg / L and the predicted carbon-to-nitrogen ratio of the denitrification filter is less than 4, the denitrification filter is taken as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-to-nitrogen ratio to the target carbon-to-nitrogen ratio.

[0005] According to the technical solution provided by the present application, the dynamic adjustment of the target carbon-to-phosphorus ratio and the target carbon-to-nitrogen ratio includes the following steps: Monitor the phosphate concentration in the influent of the high-density sedimentation tank and the total phosphorus concentration in the effluent. If the total phosphorus concentration in the effluent exceeds the standard and the phosphate concentration in the influent of the high-density sedimentation tank is on the high side, the target carbon-to-phosphorus ratio is increased to the upper limit value of the first preset range; if the absolute value of the difference between the phosphate concentration in the influent of the high-density sedimentation tank and the first compliance limit value is less than the first preset threshold value, the target carbon-to-phosphorus ratio is decreased to the lower limit value of the first preset range; Monitor the total nitrogen concentration in the effluent. If the absolute value of the difference between the total nitrogen concentration in the effluent and the first over-standard limit value is less than the second preset threshold value, the target carbon-to-nitrogen ratio is increased to the upper limit value of the second preset range; if the total nitrogen concentration in the effluent is stably up to the standard, the target carbon-to-nitrogen is gradually decreased to the lower limit value of the second preset range.

[0006] According to the technical solution provided by the present application, the influent parameter further includes the influent pH value; before the control carbon source dosing device performs the corresponding dosing operation, the following steps are further included: Select the target carbon source type according to the influent pH value: if the influent pH value is less than 6.0, ferric salt is selected; if the influent pH value is greater than or equal to 6.0 and less than 7.0, ferric salt or aluminum salt is selected; if the influent pH value is greater than or equal to 7.0 and less than 8.5, aluminum salt is selected, and if the influent pH value is greater than 8.5, aluminum salt is dosed after adjusting the pH; The control carbon source dosing device performing the corresponding dosing operation includes the following steps: Control the carbon source dosing device to dose the carbon source of the target carbon source type; Monitor the pH value in real time after dosing. If it exceeds the adaptation range of the selected target carbon source type and continues to exceed the preset duration, switch the target carbon source type to other carbon source types.

[0007] According to the technical solution provided by the present application, after monitoring the phosphate concentration of the influent and the total phosphorus concentration of the effluent of the high-density sedimentation tank, the following steps are further included: Calculate the remaining load of biological phosphorus removal according to the phosphate concentration of the influent of the high-density sedimentation tank, and dynamically allocate the phosphorus load ratio between biological phosphorus removal and chemical phosphorus removal in combination with the dosing coefficient of the chemical phosphorus removal agent. When the efficiency of biological phosphorus removal is insufficient, preferentially increase the target carbon-phosphorus ratio to strengthen biological phosphorus removal, and synchronously adjust the dosing amount of the chemical phosphorus removal agent.

[0008] According to the technical solution provided by the present application, after dynamically calculating and predicting the carbon-nitrogen ratio and the carbon-phosphorus ratio, before determining the carbon source dosing point and the first carbon source dosing amount, the following steps are further included: Monitor the sludge parameters of the biochemical reaction tank in real time, and the sludge parameters include sludge concentration and sludge volume index. Determining the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard includes the following steps: If the sludge concentration is in the third preset interval or the sludge volume index is in the fourth preset interval, determine the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard.

[0009] According to the technical solution provided by the present application, after monitoring the sludge parameters of the biochemical reaction tank in real time, the following steps are further included: If the sludge concentration is less than the lower limit value of the third preset interval or the sludge volume index is greater than the upper limit value of the fourth preset interval, increase the carbon source dosing amount by 10% - 20% on the basis of the first carbon source dosing amount as the second carbon source dosing amount. Control the carbon source dosing device to perform the corresponding dosing operation according to the carbon source dosing point and the second carbon source dosing amount.

[0010] According to the technical solution provided by the present application, after monitoring the sludge parameters of the biochemical reaction tank in real time, the following steps are further included: If the sludge concentration is greater than the upper limit value of the third preset interval and the sludge volume index is less than the lower limit value of the fourth preset interval, reduce the carbon source dosing amount by 10% - 15% on the basis of the first carbon source dosing amount as the third carbon source dosing amount. Control the carbon source dosing device to perform the corresponding dosing operation according to the carbon source dosing point and the third carbon source dosing amount.

[0011] According to the technical solution provided by the present application, the method further includes the following steps: Calculate the influent load rate and treatment cost in real time, where the treatment cost includes the carbon source cost and the pump energy consumption of the carbon source dosing device; If the influent load rate is greater than the first preset load rate and the treatment cost is greater than the first preset cost, then enable the first revised effluent water quality standard, where the key index limit value of the first revised effluent water quality standard is wider than the corresponding limit value of the preset effluent water quality standard; if the influent load rate is less than the second preset load rate and the treatment cost is less than the second preset cost, then enable the second revised effluent water quality standard, where the key index limit value of the second revised effluent water quality standard is tighter than the corresponding limit value of the preset effluent water quality standard.

[0012] According to the technical solution provided by the present application, before controlling the carbon source dosing device to perform the corresponding dosing operation, the following steps are further included: Monitor the extracellular electron transfer rate of microorganisms in the biochemical reaction tank in real time, and judge the metabolic stage of microorganisms according to the extracellular electron transfer rate, where the metabolic stage includes the metabolic trough period and the metabolic peak period; Controlling the carbon source dosing device to perform the corresponding dosing operation includes the following steps: In the metabolic trough period, control the carbon source dosing device to suspend carbon source dosing and start low-frequency pulsed aeration; in the metabolic peak period, control the carbon source dosing device to perform the corresponding dosing operation in a high-frequency intermittent dosing mode.

[0013] Compared with the prior art, the beneficial effects of the present application are as follows: The present application realizes multi-parameter dynamic coupling analysis by collecting influent parameters (COD, TN, TP, flow rate) and process parameters (anaerobic phosphate, anoxic nitrate, denitrification filter TN / COD) in real time, calculates the real-time C / N and C / P dynamically, breaks through the traditional fixed ratio limit, and selects the anaerobic tank (enhanced phosphorus removal), anoxic tank (enhanced denitrification) or denitrification filter (deep denitrification) as the dosing point according to C / N, C / P and the preset effluent standard, realizing segmented and precise supply. Among them, the preset effluent standard is also linked with the real-time water quality data to dynamically correct the target C / N and C / P, forming a "monitoring - calculation - adjustment - execution" closed-loop control. In summary, the present application reduces the carbon source dosing amount through a dynamic dosing strategy, and reduces the treatment cost per ton of water; due to accurately matching the metabolic needs of microorganisms and avoiding carbon source competition (such as the competition for electron donors between denitrifying bacteria and phosphorus-accumulating bacteria), the TN removal rate can be improved in low C / N (3-4) wastewater; in low C / P (10-15) wastewater, the TP removal rate can be improved. Through segmented dosing and closed-loop control, it is possible to avoid COD exceeding the standard caused by excessive carbon source and effectively inhibit secondary pollution. Description of the Drawings

[0014] Figure 1 The flowchart of the steps of the control method for adding carbon source in sewage treatment provided by this application; Figure 2 The schematic cross-sectional view of the pneumatic turbine motor device provided by this application. Detailed implementation manners

[0015] The following further elaborates this application in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. Additionally, it should be noted that for the convenience of description, only the parts related to the invention are shown in the drawings.

[0016] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will elaborate this application in detail with reference to the accompanying drawings and embodiments.

[0017] First, describe the mechanism of sewage treatment: 1. Enhancement of biological denitrification (denitrification) The denitrification process of sewage treatment is usually divided into two steps: (1) Nitrification: Ammonia nitrogen (NH3-N) is oxidized to nitrate (NO3 - ) under aerobic conditions.

[0018] (2) Denitrification: Nitrate (NO3 - ) is reduced to nitrogen gas (N2) under anoxic conditions.

[0019] Denitrifying bacteria need organic matter (carbon source) as an electron donor to complete the reaction. When the organic matter content in the sewage is insufficient (i.e., the C / N ratio is too low, such as industrial wastewater or sewage diluted by rainwater), the denitrification process will stagnate due to the lack of carbon source, resulting in the inability to effectively remove nitrate and the total nitrogen (TN) in the effluent exceeding the standard. Adding exogenous carbon can provide energy for denitrifying bacteria and promote the reduction of nitrate.

[0020] 2. Enhancement of biological phosphorus removal The biological phosphorus removal process mainly relies on the metabolism of polyphosphate-accumulating organisms (PAOs): Under anaerobic conditions, polyphosphate-accumulating organisms absorb organic matters such as volatile fatty acids (VFAs) in the sewage to store energy and release phosphorus; under aerobic conditions, they absorb phosphorus in excess and discharge it from the system.

[0021] If the rapidly biodegradable organic matter in the sewage is insufficient, polyphosphate-accumulating organisms cannot metabolize normally, resulting in a decline in the biological phosphorus removal efficiency. Supplementing carbon source can improve the activity of polyphosphate-accumulating organisms and enhance the phosphorus removal effect.

[0022] 3. Maintaining microbial activity When the influent water quality fluctuates (such as a high proportion of industrial wastewater), in a low-temperature environment, when the sludge ages, or when the load is too low, the carbon source in the sewage is often insufficient to maintain the basic metabolism of microorganisms, resulting in a decrease in microbial activity. The addition of a carbon source can provide the energy and carbon skeleton required for the growth of microorganisms, maintain the activity of the sludge, and prevent the system from collapsing.

[0023] 4. Common carbon sources Methanol: Low cost and fast denitrification rate, but it is toxic and has a risk of flammability; Sodium acetate: Easily degradable and high safety, but relatively high cost; Glucose: Suitable for small-scale systems, but may cause filamentous bulking; Internal carbon source: Utilize the hydrolysis products of sludge or the fermentation liquid of the primary sedimentation tank (more economical and environmentally friendly).

[0024] As mentioned in the background art, in view of the problems in the prior art, the present application proposes a control method for carbon source addition in sewage treatment, as Figure 1 shown, which includes the following steps: S1. Obtain the influent parameters at the influent end of the sewage to be treated, and the influent parameters include chemical oxygen demand, total nitrogen, total phosphorus, and flow rate; S2. Real-time monitor the process parameters of the treatment section, and the process parameters include the phosphate concentration at the end of the anaerobic tank, the nitrate concentration at the end of the anoxic tank, the total nitrogen and chemical oxygen demand at the influent of the denitrification filter. Specifically, as Figure 2 shown, the process flow involved in the present invention includes the following units: Pretreatment stage: Coarse grille → Influent pump house → Fine grille → Aerated grit chamber; Biochemical treatment section: Biochemical reaction tank (anaerobic section (carbon source addition) → anoxic section (carbon source addition) → aerobic section → effluent mixing); Advanced treatment section: Secondary sedimentation tank → High-density sedimentation tank → Denitrification filter (carbon source addition) → Disinfection. Among them, the influent parameters are collected by corresponding sensors in the pretreatment stage, and the process parameters are collected by corresponding sensors in the biochemical treatment section and the advanced treatment section. The monitored parameters include: Influent: Total phosphorus TP, COD, total nitrogen TN, flow rate (calculate C / N, C / P); Anoxic tank: End (NO3 -); High-density sedimentation tank: influent phosphate, effluent phosphate; Denitrification filter: flow rate, influent total nitrogen (TN), influent COD (calculate C / N); Effluent: total phosphorus TP, COD, total nitrogen TN; Required sensors: high-precision on-line sensors (including influent total phosphorus TP, chemical oxygen demand COD, total nitrogen TN, flow rate of the sewage treatment plant; nitrate NO3- at the outlet of the anoxic tank of the biochemical reaction tank; influent total phosphorus TP, chemical oxygen demand COD, total nitrogen TN, flow rate of the denitrification filter; effluent total phosphorus TP, chemical oxygen demand COD, total nitrogen TN of the denitrification filter; effluent total phosphorus TP, chemical oxygen demand COD, total nitrogen TN of the sewage treatment plant), with an accuracy of ±0.01 mg / L, supporting real-time data upload. Controller: industrial-grade PLC or embedded controller, supporting data acquisition, algorithm operation and equipment control. Actuator: variable-frequency metering pump (carbon source dosing device), chemical agent inventory monitoring module (ultrasonic level gauge). Support for switching and dosing of multiple carbon sources (such as sodium acetate, methanol, composite carbon source, etc.).

[0025] S3. Dynamically calculate and predict the carbon-nitrogen ratio and carbon-phosphorus ratio in real time according to the influent parameters and the process parameters; Specifically, the predicted carbon-nitrogen ratio (predicted C / N) is calculated in real time according to the influent COD and TN, and the formula is: predicted C / N = influent COD / influent TN; the predicted carbon-phosphorus ratio (predicted C / P) is calculated in real time according to the influent COD and TP, and the formula is: predicted C / P = influent COD / influent TP. At the same time, dynamic correction is also required: combining parameters such as the NO3 - concentration at the end of the anoxic tank and the influent TN of the denitrification filter, predicting future trends through a machine learning model (such as linear regression or LSTM).

[0026] S4. Determine the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, predicted carbon-phosphorus ratio and the preset effluent water quality standard, and the carbon source dosing point includes at least one of the anaerobic tank, anoxic tank and denitrification filter; Specifically, the carbon source dosing point can be selected according to the traditional threshold trigger mode, or by means of modeling the carbon source efficiency factor (CEF): CEF dosing point = , where α, β, γ: weight coefficients (default α = 0.5, β = 0.3, γ = 0.2), dynamically adjusted according to water quality fluctuations; ΔTN / TP removal rate represents the increase in the removal efficiency of target pollutants after dosing. The sludge activity recovery rate is comprehensively calculated through parameters such as MLSS, SVI, and EET. Use historical data to train a regression model (such as XGBoost) to predict the CEF values at different dosing points under different water qualities. Calculate the CEF of each dosing point in real time and preferentially select the dosing point with the highest CEF.

[0027] Further, determining the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, predicted carbon-phosphorus ratio, and preset effluent water quality standard includes the following steps: If the predicted carbon-phosphorus ratio at the inlet end is less than 15, the anaerobic tank is taken as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-phosphorus ratio to the target carbon-phosphorus ratio; the target carbon-phosphorus ratio is dynamically adjusted within a first preset range; If the nitrate concentration at the end of the anoxic tank is greater than 2.5 mg / L or the predicted carbon-nitrogen ratio at the inlet end is less than 4, the anoxic tank is taken as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-nitrogen ratio to the target carbon-nitrogen ratio; the target carbon-nitrogen ratio is dynamically adjusted within a second preset range; If the total nitrogen in the influent of the denitrification filter is greater than 15 mg / L and the predicted carbon-nitrogen ratio of the denitrification filter is less than 4, the denitrification filter is taken as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-nitrogen ratio to the target carbon-nitrogen ratio.

[0028] Further, when multiple carbon source dosing points are triggered simultaneously, the carbon source dosing amount is allocated according to the following priorities: first, meet the carbon source demand of the anoxic tank; the remaining carbon source is preferentially allocated to the anaerobic tank; the denitrification filter is only used for emergency dosing; among them, the priority allocation is based on the denitrification and phosphorus removal efficiency weights of each dosing point, the weights are obtained through training with historical data, and the weight coefficients are dynamically adjusted to minimize the total carbon source consumption.

[0029] Specifically, the first preset range is 15 - 20, the second preset range is 4 - 6. When the COD / TP of the influent of the sewage treatment plant is < 15, the carbon source dosing of the anaerobic tank is started to enhance phosphorus removal; the dosing ratio is dynamically adjusted (C / P = 15 - 20); when the NO3 at the end of the anoxic tank - > 2.5 mg / L or the influent COD / TN < 4, the carbon source dosing of the anoxic tank is started to enhance denitrification, and the dosing ratio is dynamically adjusted (C / N = 4 - 6). If the total nitrogen in the influent of the denitrification filter > 15 mg / L and the COD / TN in the influent of the denitrification filter < 4 mg / L, the emergency dosing of the denitrification filter is started, and the dosing ratio is dynamically adjusted (C / N = 4 - 6). Monitor the effluent water quality of the sewage treatment, with total phosphorus TP ≤ 0.5 mg / L, COD ≤ 50 mg / L, and total nitrogen TN ≤ 15 mg / L.

[0030] S5. Control the carbon source dosing device to perform the corresponding dosing operation according to the carbon source dosing point and the first carbon source dosing amount.

[0031] Specifically, the carbon source dosing device is configured as a variable-frequency metering pump (such as Grundfos DME series) to adjust the dosing amount according to the PLC instruction, and supports multi-carbon source switching (controlled by a three-way valve).

[0032] In a preferred embodiment, the dynamic adjustment of the target carbon-phosphorus ratio and the target carbon-nitrogen ratio includes the following steps: Monitor the phosphate concentration of the influent water and the total phosphorus concentration of the effluent water in the high-density sedimentation tank; If the total phosphorus concentration of the effluent exceeds the standard and the phosphate concentration of the influent water in the high-density sedimentation tank is relatively high, raise the target carbon-phosphorus ratio to the upper limit value of the first preset range; if the absolute value of the difference between the phosphate concentration of the influent water in the high-density sedimentation tank and the first compliance limit value is less than the first preset threshold value, lower the target carbon-phosphorus ratio to the lower limit value of the first preset range; Monitor the total nitrogen concentration of the effluent water; If the absolute value of the difference between the total nitrogen concentration of the effluent water and the first over-standard limit value is less than the second preset threshold value, raise the target carbon-nitrogen ratio to the upper limit value of the second preset range; if the total nitrogen concentration of the effluent water reaches the standard stably, gradually lower the target carbon-nitrogen ratio to the lower limit value of the second preset range.

[0033] Specifically, the absolute value of the difference between the phosphate concentration of the influent water in the high-density sedimentation tank and the first compliance limit value (the phosphate concentration of the influent water in the high-density sedimentation tank is less than the first compliance limit value) is less than the first preset threshold value, which means that the phosphate concentration of the influent water in the high-density sedimentation tank has been on the verge of compliance (≤ 105% of the limit value), and it is necessary to carefully control the addition of carbon source; the absolute value of the difference between the total nitrogen concentration of the effluent water and the first over-standard limit value is less than the second preset threshold value, which means that the total nitrogen concentration of the effluent water is very close to exceeding the standard (≥ 95% of the limit value and not exceeding the standard), and it is necessary to increase the carbon-nitrogen ratio to strengthen denitrification.

[0034] In a preferred embodiment, after monitoring the phosphate concentration of the influent water and the total phosphorus concentration of the effluent water in the high-density sedimentation tank, the following steps are further included: Calculate the remaining load of biological phosphorus removal according to the phosphate concentration of the influent water in the high-density sedimentation tank, and dynamically allocate the phosphorus load ratio of biological phosphorus removal and chemical phosphorus removal in combination with the dosing coefficient of chemical phosphorus removal agent; When the efficiency of biological phosphorus removal is insufficient, preferentially increase the target carbon-phosphorus ratio to strengthen biological phosphorus removal, and synchronously adjust the dosing amount of chemical phosphorus removal agent.

[0035] Specifically, the dynamic adjustment of the target carbon-phosphorus ratio is as follows: monitor the phosphate concentration of the influent water in the high-density sedimentation tank, and calculate the remaining load of biological phosphorus removal through the formula: (where is the phosphate concentration of the influent water in the high-density sedimentation tank, and the coefficient 3.066 is for the conversion of phosphorus molar mass, (i.e., the remaining load for biological phosphorus removal). If the total phosphorus concentration in the effluent (effluent TP) exceeds the standard and the phosphate concentration in the influent of the high-density sedimentation tank is relatively high (e.g., > 0.5 mg / L), gradually increase the target C / P from 15 to 20 to strengthen biological phosphorus removal. Synchronously adjust the dosage of the chemical phosphorus removal agent (such as PAC), formula: .

[0036] Specifically, the dynamic adjustment of the target carbon-nitrogen ratio is as follows: Monitor the TN concentration in the effluent. If it is close to the limit value (e.g., TN > 12 mg / L), increase the target C / N to 6 at a rate of +0.2 per hour. If the TN in the effluent is stably up to the standard (≤ 10 mg / L for 12 consecutive hours), decrease the target C / N to 4 at a rate of -0.25 every 12 hours. Supplementary additional carbon source: When NO3 - > 2.5 mg / L at the end of the anoxic tank, additional carbon source needs to be supplemented, and the additional supplement amount = NO3 - × 2.86 / COD equivalent of the carbon source.

[0037] In a preferred embodiment, the influent parameters further include the influent pH value; before the control carbon source dosing device performs the corresponding dosing operation, the following steps are further included: Select the target carbon source type according to the influent pH value: If the influent pH value is less than 6.0, ferric salt is selected; if the influent pH value is greater than or equal to 6.0 and less than 7.0, ferric salt or aluminum salt is selected; if the influent pH value is greater than or equal to 7.0 and less than 8.5, aluminum salt is selected; if the influent pH value is greater than 8.5, adjust the pH and then add aluminum salt; The control carbon source dosing device performing the corresponding dosing operation includes the following steps: Control the carbon source dosing device to add the carbon source of the target carbon source type; Real-time monitor the pH value after dosing. If it exceeds the adaptation range of the selected target carbon source type and continues to exceed the preset duration, switch the target carbon source type to other carbon source types.

[0038] Specifically, pH < 6.0: Select ferric salt (such as FeCl3), and ferric ions are prone to form FePO4 precipitate under acidic conditions. pH 6.0 - 7.0: Ferric salt or aluminum salt (such as Al2(SO4)3), and the phosphorus removal effect of aluminum salt is better under neutral conditions. pH ≥ 7.0: Aluminum salt (such as PAC), and the ability of Al(OH)3 colloid to adsorb phosphorus is enhanced under alkaline conditions. pH > 8.5: Acid needs to be added to adjust to below 8.5 before adding aluminum salt to avoid the dissolution of Al(OH)3 colloid. Different pH values affect the hydrolysis form of metal salts, and thus affect the phosphorus removal efficiency. Therefore, the carbon source type needs to be selected according to the actual situation.

[0039] Further, after selecting the target carbon source type according to the influent pH value and controlling the carbon source dosing device to dose the carbon source of the target carbon source type, the following steps are further included: Real-time monitor the microbial respiration quotient (OUR) and the carbon source fitness of the target carbon source type; Specifically, the respiration quotient (Oxygen Utilization Rate, OUR) is measured in real time by an on-line respirometer, reflecting the microbial metabolism intensity (μmol O2 / g MLSS·h), and the carbon source fitness (CAI) is obtained by the formula: ; where The removal rate refers to the change in nitrate concentration at the end of the anoxic tank, and SV30 refers to the sludge sedimentation volume in 30 minutes, reflecting the sludge sedimentation property.

[0040] If the carbon source fitness is less than the first fitness and the microbial respiration quotient is less than the first microbial respiration quotient, then retrieve the carbon source database to match the adaptable carbon source; Among them, the first fitness is 0.6, indicating poor adaptability between the carbon source and microorganisms when it is less than 0.6. The first microbial respiration quotient is 1.2 μmolO2 / g MLSS·h. When the first fitness is less than 0.6 and the first microbial respiration quotient is less than 1.2, dynamic carbon source switching is triggered. The carbon source database includes multiple carbon source types, as well as the adaptation scenarios and historical performance data of each carbon source type. The adaptation scenarios include salinity (Cl - concentration), temperature, pH, respiration quotient threshold, and the historical performance data includes denitrification rate, sludge property change, and cost after dosing; matching the adaptable carbon source includes: matching the adaptable carbon source from the database according to the real-time salinity, microbial respiration quotient, and carbon source fitness. Among them, the denitrification efficiency weight (40%), the sludge stability weight (30%), and the cost weight (30%).

[0041] Specifically, adjust the carbon source dosing amount in the anaerobic tank in coordination with the dosing of chemical phosphorus remover; Monitor parameters: Monitor the influent COD and TP of the sewage treatment plant and calculate COD / TP. When the influent C / P of the sewage treatment plant < 15, start dosing the carbon source in the anaerobic tank to strengthen phosphorus removal; when C / P ≥ 15, there is no need to dose the carbon source. Set the initial target C / P value (initially recommended to set a relatively high value), ΔC=(target C / P×P in )-C in ; if ΔC is negative (i.e., the influent C / P is already higher than the target value), then there is no need to dose. Dynamically adjust the target C / P, and the adjustment range is C / P = 15~20; if the phosphorus concentration after biological treatment is high (phosphate concentration at the inlet of the high-density sedimentation tank), resulting in an increase in the dosage of chemical phosphorus remover, then gradually increase the target C / P (approaching 20). If the effluent TP is stable and the dosage of chemical phosphorus remover is low, the target C / P can be appropriately reduced (approaching 15) to reduce carbon source consumption.

[0042] Meanwhile, biological phosphorus removal is synergistic with chemical phosphorus removal: Monitor the phosphate concentration at the inlet of the high-density sedimentation tank, convert it into the total phosphorus concentration, and the amount of phosphorus to be removed by chemical phosphorus removal: ΔP = TP bio -0.5 mg / L. The intelligent dosing system for phosphorus removal agent can calculate the dosing amount of chemical phosphorus removal agent. According to experience, for every 1 mg / L removed 10 - 15 mg / L of PAC needs to be dosed (calculated according to the type of phosphorus removal agent) Closed-loop feedback: Monitor the effluent quality of the sewage treatment plant and adjust the dosing strategies of carbon source and phosphorus removal agent; The effluent requires a total phosphorus TP ≤ 0.5 mg / L; If the effluent TP exceeds the standard and the phosphate concentration at the inlet of the high-density sedimentation tank is high, the target C / P (close to 20) should be preferentially increased to strengthen biological phosphorus removal.

[0043] If the phosphate concentration at the inlet of the high-density sedimentation tank is low (e.g., close to 0.5 mg / L), gradually reduce the target C / P and adjust the dosing amount of the phosphorus removal agent accordingly. While ensuring that the effluent TP meets the standard stably, minimize the dosing amounts of carbon source and phosphorus removal agent to control the lowest cost of phosphorus removal dosing.

[0044] Example 2 Based on Example 1, this example also proposes a method to further improve the control accuracy, specifically including: In a preferred embodiment, after dynamically calculating and predicting the carbon-nitrogen ratio and the carbon-phosphorus ratio, before determining the carbon source dosing point and the first carbon source dosing amount, the following steps are further included: Real-time monitor the sludge parameters of the biochemical reaction tank, and the sludge parameters include sludge concentration and sludge volume index; The determining of the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent quality standard includes the following steps: If the sludge concentration is within the third preset interval or the sludge volume index is within the fourth preset interval, then determine the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent quality standard.

[0045] Further, after the real-time monitoring of the sludge parameters of the biochemical reaction tank, the following steps are further included: If the sludge concentration is less than the lower limit value of the third preset interval or the sludge volume index is greater than the upper limit value of the fourth preset interval, then increase the carbon source dosing amount by 10% - 20% on the basis of the first carbon source dosing amount as the second carbon source dosing amount; Control the carbon source dosing device to perform the corresponding dosing operation according to the carbon source dosing point and the second carbon source dosing amount.

[0046] Further, after monitoring the sludge parameters of the real-time monitoring biochemical reaction tank, the following steps are further included: If the sludge concentration is greater than the upper limit value of the third preset interval and the sludge volume index is less than the lower limit value of the fourth preset interval, then reduce the carbon source dosage by 10% - 15% on the basis of the first carbon source dosage as the third carbon source dosage; According to the carbon source dosing point and the third carbon source dosage, control the carbon source dosing device to perform the corresponding dosing operation.

[0047] Specifically, the aerobic tank is the core area of the activated sludge process. The state of the end mixed liquor directly affects the sludge return ratio and the sedimentation effect of the secondary sedimentation tank. Therefore, in this embodiment, the sludge parameters are monitored at the end of the aerobic tank. The normal range of the sludge concentration (MLSS) is 3000 - 5000 mg / L. The sludge concentration (MLSS) is monitored by an online MLSS sensor (such as an optical scattering type, ultrasonic type), which is immersed in the end mixed liquor of the aerobic tank at a height of 1 / 3 from the bottom of the tank (to avoid aeration interference). The sludge volume index (SVI) is monitored by an SVI automatic analyzer (requiring a sampling device). The sampling point can be set near the effluent weir at the end of the aerobic tank. The analyzer can be external or integrated into the online monitoring platform. The normal range of the sludge volume index (SVI) is 50 - 150 mL / g. The adjustment strategy is as follows: If MLSS < 3000 mg / L or SVI > 150 mL / g (indicating sludge aging), increase the carbon source by 10% - 20% to promote microbial proliferation. If MLSS > 5000 mg / L and SVI < 50 mL / g (indicating the risk of sludge bulking), reduce the carbon source by 10% - 15% to avoid excessive COD load.

[0048] In a preferred embodiment, the method further includes the following steps: Real-time calculate the influent load rate and the treatment cost, where the treatment cost includes the carbon source cost and the pump energy consumption of the carbon source dosing device; If the influent load rate is greater than the first preset load rate and the treatment cost is greater than the first preset cost, then enable the first revised effluent water quality standard, where the key index limit value of the first revised effluent water quality standard is wider than the corresponding limit value of the preset effluent water quality standard; if the influent load rate is less than the second preset load rate and the treatment cost is less than the second preset cost, then enable the second revised effluent water quality standard, where the key index limit value of the second revised effluent water quality standard is stricter than the corresponding limit value of the preset effluent water quality standard.

[0049] Specifically, the treatment cost = unit price of carbon source × dosage + energy consumption of pump × electricity price; Load rate calculation: Inlet load rate = actual flow / designed flow × 100%; The first preset load rate can be selected as 120%, and the second preset load rate can be selected as 80%. If the load rate > 120% and the cost > the preset value, the effluent TN is relaxed to 18 mg / L (the original standard is 15 mg / L). If the load rate < 80% and the cost < the preset value, the effluent standard is improved to TN ≤ 10 mg / L.

[0050] Specifically, when the inlet load rate is greater than the first preset load rate and the treatment cost is greater than the first preset cost, this usually occurs when the inlet pollution load is high, the treatment difficulty is large, and the operating cost is high (such as during rainstorm impacts or when industrial wastewater mixes in, causing a sharp increase in the inlet concentration). At this time, in order to ensure the stable operation of the system, avoid collapse, and control costs, relaxing the effluent water quality standard (i.e., allowing the effluent indicators to exceed the standard temporarily within a certain range) is an emergency strategy. The purpose is to prioritize ensuring that the treatment facilities do not break down, accept short-term water quality fluctuations, and then restore the preset effluent water quality standard after the load peak or abnormal situation has passed; Optionally, the limits of total nitrogen, total phosphorus, and chemical oxygen demand in the preset effluent water quality standard are respectively relaxed to 1.2 times, 1.15 times, and 1.1 times the original limits to obtain the first corrected effluent water quality standard. In addition, when the inlet load rate is less than the second preset load rate and the treatment cost is less than the second preset cost, this usually occurs when the inlet pollution load is low, the treatment difficulty is small, and the operating cost is low (such as at night or during the low-flow period in the dry season). At this time, the system has sufficient redundant treatment capacity. According to the logic of optimized operation, this low-cost window period should be utilized to pursue higher treatment efficiency or better effluent water quality, so the effluent water quality standard is tightened. Optionally, the limits of total nitrogen, total phosphorus, and chemical oxygen demand in the preset effluent water quality standard are respectively tightened to 0.85 times, 0.85 times, and 0.85 times the original limits to obtain the second corrected effluent water quality standard.

[0051] In a preferred embodiment, before the control carbon source dosing device performs the corresponding dosing operation, the following steps are further included: Real-time monitor the extracellular electron transfer rate of microorganisms in the biochemical reaction tank, and based on the extracellular electron transfer rate, judge the metabolic stage of the microorganisms, where the metabolic stage includes the metabolic trough period and the metabolic peak period; Specifically, the extracellular electron transfer rate of microorganisms in the anaerobic tank and anoxic tank of the biochemical reaction pool is monitored in real time; if the extracellular electron transfer rate of the anaerobic tank is lower than the third preset threshold and the extracellular electron transfer rate of the anoxic tank is lower than the fourth preset threshold, it is determined that the microorganisms are in the metabolic trough period; if the extracellular electron transfer rate of the anaerobic tank is higher than the third preset threshold or the extracellular electron transfer rate of the anoxic tank is higher than the fourth preset threshold, it is determined that the microorganisms are in the metabolic peak period; the extracellular electron transfer (EET) of polyphosphate-accumulating organisms (PAOs) in the anaerobic tank is usually lower than 50 μA / cm² during the metabolic trough period (such as insufficient carbon source or low temperature conditions), so the third preset threshold can be selected as 50 μA / cm². The EET activity of denitrifying bacteria is relatively high under anoxic conditions, but it can drop below 80 μA / cm² during the metabolic trough period (such as insufficient carbon source or dissolved oxygen fluctuations), so the fourth preset threshold can be selected as 80 μA / cm².

[0052] The control of the carbon source dosing device to perform the corresponding dosing operation includes the following steps: During the metabolic trough period, control the carbon source dosing device to suspend carbon source dosing and start low-frequency pulsed aeration; during the metabolic peak period, control the carbon source dosing device to perform the corresponding dosing operation in a high-frequency intermittent dosing mode.

[0053] Specifically, the extracellular electron transfer rate (EET) reflects the electron transfer activity of microorganisms and is directly related to the metabolic intensity. It is monitored by an electrochemical sensor (such as a microbial fuel cell). The layout method is as follows: Anaerobic tank: The electrode group (anode + cathode) is buried in the sludge layer, with a spacing of 10 - 20 cm. Anoxic tank: The electrode group is installed in the first 1 / 3 area in the flow direction. During the metabolic trough period, control the carbon source dosing device to suspend carbon source dosing and start low-frequency pulsed aeration (0.1 Hz) in the anaerobic tank and anoxic tank to maintain dissolved oxygen. During the metabolic peak period, select the high-frequency intermittent dosing mode for the corresponding tank body according to the carbon source dosing point. Starting aeration during the trough period can relieve the inhibition of sludge activity (such as the increase in dissolved oxygen promoting the metabolism of aerobic bacteria). During the peak period, perform high-frequency dosing according to the determined carbon source dosing point above (such as when only the anoxic tank needs to supplement carbon, only dose this tank, such as dosing for 10 seconds every 5 minutes) to match the absorption rate of microorganisms.

[0054] Example 3 The influent flow rate Q of the sewage treatment plant 水 = 10000 m³ / d, influent TP = 15 mg / L, COD = 220 mg / L, the effluent requirement for total phosphorus TP ≤ 0.5 mg / L, and the total phosphorus control target TP ≤ 0.45 mg / L is set at the outlet of the high-density sedimentation tank; the carbon source is sodium acetate solution (COD equivalent 0.78 g COD / g, concentration 40% solution, density 820 g / L) COD / TP = 14.67 < 15, start carbon source dosing in the anaerobic tank to enhance phosphorus removal; Set the initial target C / P = 18 to maximize the biological phosphorus removal efficiency ΔC = [(target C / P × P in ) - C in ÷ 0.78 = (18 × 15 - 220) ÷ 0.78 = 64.10 mg / L Calculation of carbon source dosage: L / d = 81.43 L / h Influent phosphate in the high-density sedimentation tank ( ) = 1.8 mg / L TP bio ≈ 1.8 ÷ 3.066 = 0.587 mg / L Chemical phosphorus removal amount ΔP = 0.587 - 0.45 = 0.137 mg / L Dosage of chemical phosphorus remover (PAC), initially according to the removal of 1 mg / L 12 mg / L of PAC needs to be added D = ΔP × k = 0.137 × 12 = 1.644 mg / L Q PAC = D × Q 水 ÷ 1000 = 1.644 × 10000 ÷ 1000 = 16.44 L / d Monitor the effluent TP of the sewage treatment plant = 0.55 mg / L > 0.5 mg / L (still exceeding the standard) Increase the target C / P to 20 to strengthen biological phosphorus removal ΔC = [(target C / P × P in ) - C in ÷ 0.78 = (20 × 15 - 220) ÷ 0.78 = 102.56 mg / L Calculation of carbon source dosage: L / d = 130.28 L / h Monitor the influent phosphate in the high-density sedimentation tank ( ) = 1.6 mg / L TP bio ≈ 1.6 ÷ 3.066 = 0.522 mg / L Chemical phosphorus removal amount ΔP = 0.522 - 0.45 = 0.072 mg / L Dosage of chemical phosphorus remover (PAC), initially according to the removal of 1 mg / L 12 mg / L of PAC needs to be added D = ΔP × k = 0.072 × 12 = 0.864 mg / L Q PAC = D × Q 水÷1000 = 0.864×10000÷1000 = 8.64 L / d After adjustment, the monitored TP of the sewage treatment plant effluent = 0.45 mg / L < 0.5 mg / L Implementation effect data

[0055] In summary, this embodiment realizes the coordination of carbon source addition in the anaerobic tank and chemical phosphorus removal. When the influent C / P < 15, the anaerobic tank is selected as the carbon source addition point, and the target C / P is dynamically adjusted to 15 - 20 (the first preset range), and the carbon source addition amount is calculated. By monitoring the phosphate concentration in the influent of the high-density sedimentation tank and the total phosphorus concentration in the effluent, the target C / P is dynamically adjusted (for example, from 15 to 20) to strengthen biological phosphorus removal. According to the remaining load of biological phosphorus removal, the phosphorus load ratio of biological and chemical phosphorus removal is dynamically allocated (for example, calculating the PAC addition amount through a formula).

[0056] Example 4 The influent flow rate Q of the sewage treatment plant 水 = 20000 m³ / d, influent TP = 15 mg / L, COD = 300 mg / l, the required total phosphorus TP in the effluent ≤ 0.5 mg / L, and the set total phosphorus control target TP ≤ 0.48 mg / L at the outlet of the high-density sedimentation tank The carbon source is methanol (COD equivalent 1.5 gCOD / g, concentration 99% solution, density 790 g / L).

[0057] COD / TP = 20, no carbon source needs to be added to the anaerobic tank; Phosphate in the influent of the high-density sedimentation tank ( ) = 1.7 mg / L TP bio ≈ 1.7÷3.066 = 0.554 mg / L The chemical phosphorus removal amount ΔP = 0.554 - 0.48 = 0.074 mg / L The addition amount of chemical phosphorus removal agent (PAC), initially according to removing 1 mg / L 12 mg / L PAC needs to be added D = ΔP×k = 0.074×12 = 0.888 mg / L Q PAC = D×Q 水 ÷1000 = 0.888×20000÷1000 = 17.76 L / d The monitored TP of the sewage treatment plant effluent = 0.52 mg / L > 0.5 mg / L (still exceeding the standard) Adjust the addition amount of chemical phosphorus removal agent (PAC), according to removing 1 mg / L 15 mg / L PAC needs to be added D = ΔP × k = 0.074 × 15 = 1.11 mg / L Q PAC = D × Q 水 ÷ 1000 = 1.11 × 20000 ÷ 1000 = 22.2 L / d After adjustment, the monitored TP in the effluent of the sewage treatment plant = 0.45 mg / L < 0.5 mg / L Implementation effect data

[0058] (2) Adjust the carbon source dosage in the anoxic tank to cooperate with the emergency carbon source dosage in the denitrification filter Priority of carbon source dosage: Preferentially use the dosage in the anoxic tank to make full use of the potential of pre-denitrification. The dosage in the denitrification filter is only for emergency and is activated when the TN in the influent of the filter > 15 mg / L due to insufficient denitrification in the anoxic tank.

[0059] A - Adjust the carbon source dosage in the anoxic tank ① Monitoring parameters Monitor the influent COD and TN of the sewage treatment plant and calculate COD / TN.

[0060] ② Triggering conditions Carbon source dosage in the anoxic tank: When the influent COD / TN of the sewage treatment plant < 4 or the end of the anoxic tank > 2.5 mg / L, start the carbon source dosage in the anoxic tank to strengthen denitrification; ③ Dynamically adjust the target C / N Adjustment range C / P = 4 - 6, monitor the TN concentration in the effluent in real time, and correct the target C / N value and carbon source dosage coefficient through closed-loop feedback ④ Calculation of carbon source dosage Set the initial target C / N value (initially recommended to set a high value, such as 5) ΔC = (target C / N × N in ) - C in When the end of the anoxic tank > 2.5 mg / L, additional carbon source dosage: ΔC additional = × 2.86 carbon source COD equivalent (calculated according to the theoretical carbon requirement for denitrification) Among them, 2.86 is the amount of COD required for denitrifying 1 mg of nitrate nitrogen (mg) B - Emergency dosage in the denitrification filter ① Monitoring parameters Monitor the influent COD and TN of the denitrification filter and calculate COD / TN.

[0061] ② Triggering conditions Carbon source addition for denitrification filter: When the total nitrogen in the influent of the denitrification filter > 15 mg / L and the COD / TN in the influent of the denitrification filter < 4 mg / L, start the emergency addition of the denitrification filter to enhance nitrogen removal.

[0062] ③ Dynamically adjust the target C / N Adjust the range C / P = 4 - 6, monitor the TN concentration of the effluent in real time, and correct the target C / N value and carbon source addition coefficient through closed-loop feedback.

[0063] ④ Calculate the carbon source addition amount Set the initial target C / N value (it is not recommended to set it too high initially, such as 4.5) ΔC=(target C / N × N in ) - C in C - Dynamic optimization strategy ① Adaptive adjustment of the target C / N Upward adjustment conditions: Effluent TN > 12 mg / L (close to the limit) → The target C / N is gradually increased to 6 at a certain rate (for example, the initial rate is +0.2 per hour, and the subsequent upward adjustment rate is determined by self-learning based on feedforward and feedback data).

[0064] At the end of the anoxic tank > 2.5 mg / L per unit time of duration → The target C / N + a certain value (for example, initially, for every 1 hour of duration, the target C / N increases by 0.5, and the subsequent upward adjustment rate is determined by self-learning based on feedforward and feedback data).

[0065] Downward adjustment conditions: The effluent TN is not higher than the set limit for a certain continuous time → The target C / N is gradually decreased to 4 at a certain rate (for example, when the effluent TN ≤ 10 mg / L for 12 consecutive hours, the target C / N is gradually decreased to 4 by -0.25 every 12 hours).

[0066] D - Closed-loop feedback Monitor the TN of the effluent quality of the sewage treatment plant, and the total phosphorus TN of the effluent is required to be ≤ 15 mg / L If the effluent TN > 15 mg / L, immediately start the maximum carbon source addition (target C / N = 6) and alarm.

[0067] Redundant design: Set the internal control target TN ≤ 12 mg / L, with a buffer margin of 3 mg / L reserved.

[0068] Prevent over-addition: When the carbon source addition amount has not changed for 6 consecutive hours and the effluent TN is stable, automatically reduce the target C / N to 4.5.

[0069] In summary, this embodiment realizes chemical phosphorus removal as the main method under high C / P influent. When the influent C / P = 20 (biological phosphorus removal is not required), it completely relies on chemical phosphorus removal and dynamically adjusts the PAC dosage (from 12 mg / L to 15 mg / L). By calculating the treatment cost (PAC cost) and the influent loading rate (Q = 20000 m³ / d), the dosage of the chemical phosphorus removal agent is optimized to reduce the cost.

[0070] Example 5 The influent flow rate Q of the sewage treatment plant 水 = 20000 m³ / d, the effluent water quality standard is TN ≤ 15 mg / L, and the safety margin control target is TN ≤ 12 mg / L. Carbon source type and parameters: Sodium acetate (COD equivalent 0.78 g COD / g, concentration 40% solution, density 820 g / L).

[0071] The influent COD of the sewage treatment is 80 mg / L, the influent TN is 25 mg / L, and the influent COD / TN = 3.2 < 4. Carbon source addition is started in the anoxic tank. The end of the anoxic tank = 3 mg / L, and the additional carbon source amount is supplemented.

[0072] Set the initial target C / N value = 5 The basic carbon source addition ΔC = [(target C / N × N in ) - C in / 0.78 = (5 × 25 - 80) / 0.78 = 57.69 mg / L The additional carbon source ΔC 额外 = Δ × 2.86 / 0.78 = (3 - 2.5) × 2.86 / 0.78 = 1.83 mg / L The total carbon source addition = 57.69 + 1.83 = 59.52 mg / L The dosage of the sodium acetate solution = 59.52 × 20000 / (0.4 × 820) = 3629.27 L / d = 151.22 L / h The influent TN of the denitrification filter is 10 mg / L, and no carbon source needs to be added The effluent TN = 9.5 mg / L, meeting the set limit requirements and stably reaching the standard.

[0073] The effluent TN is ≤ 10 mg / L for 12 consecutive hours, and the target C / N is gradually reduced to 4.75 by -0.25 every 12 hours. The carbon source addition ΔC = [(target C / N × N in ) - C in / 0.78 = (4.75 × 25 - 80) / 0.78 = 49.68 mg / L The end of the anoxic tank = 2.6 mg / L > 2.5 mg / L, additional carbon source needs to be supplemented.

[0074] Additional carbon source supplement ΔC 额外 = Δ × 2.86 / 0.78 = (2.6 - 2.5) × 2.86 / 0.78 = 0.37 mg / L Therefore, the total carbon source dosage = 49.68 + 0.37 = 50.04 mg / L Sodium acetate solution dosage = 50.04 × 20000 / (0.4 × 820) = 3051.22 L / d = 127.13 L / h TN of the influent to the denitrification filter = 12 mg / L, no carbon source needs to be added TN of the effluent = 11.5 mg / L, meeting the set limit requirements and stably meeting the standards.

[0075] Implementation effect data

[0076] In summary, when the influent C / N = 3.2 < 4, select the anoxic tank as the dosing point, and the target C / N is dynamically adjusted (from 5 to 4.75). Adjust the target C / N through the closed-loop feedback of the TN concentration in the effluent (for example, gradually lower it after continuous compliance). The carbon source dosage can be adjusted in combination with sludge parameters (MLSS, SVI) (for example, increase the dosage by 10% - 20% when MLSS < 3000 mg / L).

[0077] Example 6 Influent flow rate Q of the sewage treatment plant 水 = 10000 m³ / d, the effluent water quality standard is TN ≤ 15 mg / L, and the safety margin control target is TN ≤ 12 mg / L. Carbon source type and parameters: methanol (COD equivalent 1.5 gCOD / g, concentration 99% solution, density 790 g / L).

[0078] Sewage treatment influent COD = 150 mg / L, influent TN = 40 mg / L, influent COD / TN = 3.75 < 4, start carbon source dosing in the anoxic tank. At the end of the anoxic tank = 2.6 mg / L, no additional carbon source needs to be supplemented.

[0079] Set the initial target C / N value = 5 Basic carbon source dosing ΔC = [(target C / N × N in ) - C in / 1.5 = (5 × 40 - 150) / 1.5 = 33.33 mg / L Additional carbon source supplement ΔC 额外 = ×2.86 / 1.5 = (2.6 - 2.5) × 2.86 / 1.5 = 0.19 mg / L Total carbon source dosage = 33.33 + 0.19 = 33.52 mg / L Methanol solution dosage = 33.52 × 10000 / (0.99 × 790) = 428.59 L / d = 17.86 L / h TN of the influent to the denitrification filter = 16 mg / L > 15 mg / L, influent COD = 50 mg / L, C / N = 2.78 < 4, start carbon source dosing for the denitrification filter Set the initial target C / N value = 4.5 Carbon source dosing ΔC = [(Target C / N × N in ) - C in / 1.5 = (4.5 × 16 - 50) / 1.5 = 14.67 mg / L Methanol solution dosage = 14.67 × 10000 / (0.99 × 790) = 187.57 L / d = 7.82 L / h TN of the effluent = 14 mg / L, meeting the set limit requirements and stably meeting the standards.

[0080] Implementation effect data

[0081] In summary, when TN of the influent to the denitrification filter > 15 mg / L and C / N < 4, trigger the dosing of the denitrification filter, select the carbon source type according to the influent pH (methanol is applicable in the neutral pH range), and monitor the pH in real time after dosing. Subsequently, by monitoring the extracellular electron transfer rate (EET) of microorganisms, adopt a high-frequency intermittent dosing mode during the metabolic peak period.

[0082] In this article, specific examples are used to elaborate on the principles and implementation methods of this application. The descriptions of the above embodiments are only used to help understand the method and its core idea of this application. The above are only the preferred implementation methods of this application. It should be noted that due to the limitations of literal expression, and objectively there are infinite specific structures. For those of ordinary skill in the art in this technical field, without departing from the principles of the present invention, several improvements, modifications or changes can also be made, or the above technical features can be combined in an appropriate manner; these improvements, modifications, changes or combinations, or directly applying the concept and technical solution of the invention to other occasions without improvement, should all be regarded as the protection scope of this application.

Claims

1. A control method for adding carbon source in sewage treatment, characterized in that, It includes the following steps: Obtain the influent parameters at the influent end of the sewage to be treated, where the influent parameters include chemical oxygen demand, total nitrogen, total phosphorus, and flow rate; Monitor the process parameters of the treatment section in real time, where the process parameters include the phosphate concentration at the end of the anaerobic tank, the nitrate concentration at the end of the anoxic tank, the total nitrogen and chemical oxygen demand of the influent to the denitrification filter; Dynamically calculate the predicted carbon-nitrogen ratio and the predicted carbon-phosphorus ratio in real time according to the influent parameters and the process parameters; Based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and the preset effluent water quality standard, determine the carbon source dosing point and the first carbon source dosing amount, where the carbon source dosing point includes at least one of the anaerobic tank, the anoxic tank, and the denitrification filter; According to the carbon source dosing point and the first carbon source dosing amount, control the carbon source dosing device to perform the corresponding dosing operation.

2. The control method for adding carbon source in sewage treatment according to claim 1, wherein: The step of determining the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and the preset effluent water quality standard includes the following steps: If the predicted carbon-phosphorus ratio at the influent end is less than 15, then use the anaerobic tank as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-phosphorus ratio to the target carbon-phosphorus ratio; the target carbon-phosphorus ratio is dynamically adjusted within the first preset range; If the nitrate concentration at the end of the anoxic tank is greater than 2.5 mg / L or the predicted carbon-nitrogen ratio at the influent end is less than 4, then use the anoxic tank as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-nitrogen ratio to the target carbon-nitrogen ratio; the target carbon-nitrogen ratio is dynamically adjusted within the second preset range; If the total nitrogen of the influent to the denitrification filter is greater than 15 mg / L and the predicted carbon-nitrogen ratio of the denitrification filter is less than 4, then use the denitrification filter as the carbon source dosing point, and the first carbon source dosing amount is the first carbon source dosing amount required to adjust the predicted carbon-nitrogen ratio to the target carbon-nitrogen ratio.

3. The control method for adding carbon source in sewage treatment according to claim 2, wherein: The dynamic adjustment of the target carbon-phosphorus ratio and the target carbon-nitrogen ratio includes the following steps: Monitor the phosphate concentration of the influent to the high-density sedimentation tank and the total phosphorus concentration of the effluent; If the total phosphorus concentration of the effluent exceeds the standard and the phosphate concentration of the influent to the high-density sedimentation tank is on the high side, then increase the target carbon-phosphorus ratio to the upper limit value of the first preset range; if the absolute value of the difference between the phosphate concentration of the influent to the high-density sedimentation tank and the first compliance limit value is less than the first preset threshold, then decrease the target carbon-phosphorus ratio to the lower limit value of the first preset range; Monitor the total nitrogen concentration of the effluent; If the absolute value of the difference between the total nitrogen concentration of the effluent and the first over-standard limit value is less than the second preset threshold, then increase the target carbon-nitrogen ratio to the upper limit value of the second preset range; if the total nitrogen concentration of the effluent is stably up to standard, then gradually decrease the target carbon-nitrogen to the lower limit value of the second preset range.

4. The control method for adding carbon source in sewage treatment according to claim 1, characterized in that: The influent parameters further include the influent pH value; before controlling the carbon source dosing device to perform the corresponding dosing operation, the following steps are further included: Select the target carbon source type according to the influent pH value: If the influent pH value is less than 6.0, ferric salts are selected; if the influent pH value is greater than or equal to 6.0 and less than 7.0, ferric salts or aluminum salts are selected; if the influent pH value is greater than or equal to 7.0 and less than 8.5, aluminum salts are selected; if the influent pH value is greater than 8.5, adjust the pH and then add aluminum salts. The control carbon source dosing device performs corresponding dosing operations, including the following steps: Control the carbon source dosing device to dose the carbon source of the target carbon source type. Real-time monitor the pH value after dosing. If it exceeds the adaptation range of the selected target carbon source type and continues to exceed the preset duration, switch the target carbon source type to other carbon source types.

5. The control method for adding carbon source in sewage treatment according to claim 3, characterized in that: After monitoring the influent phosphate concentration and the effluent total phosphorus concentration of the high-density sedimentation tank, the following steps are also included: Calculate the remaining biological phosphorus removal load according to the influent phosphate concentration of the high-density sedimentation tank, and dynamically allocate the phosphorus load ratio of biological phosphorus removal and chemical phosphorus removal in combination with the chemical phosphorus removal agent dosing coefficient. When the biological phosphorus removal efficiency is insufficient, preferentially increase the target carbon-phosphorus ratio to strengthen biological phosphorus removal, and synchronously adjust the dosing amount of the chemical phosphorus removal agent.

6. The control method for adding carbon source in sewage treatment according to claim 1, characterized in that: Before determining the carbon source dosing point and the first carbon source dosing amount after dynamically calculating the predicted carbon-nitrogen ratio and the predicted carbon-phosphorus ratio, the following steps are also included: Real-time monitor the sludge parameters of the biochemical reaction tank, and the sludge parameters include sludge concentration and sludge volume index. Based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard, determining the carbon source dosing point and the first carbon source dosing amount includes the following steps: If the sludge concentration is in the third preset interval or the sludge volume index is in the fourth preset interval, determine the carbon source dosing point and the first carbon source dosing amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard.

7. The control method for adding carbon source in sewage treatment according to claim 6, wherein: After real-time monitoring the sludge parameters of the biochemical reaction tank, the following steps are also included: If the sludge concentration is less than the lower limit of the third preset interval or the sludge volume index is greater than the upper limit of the fourth preset interval, increase the carbon source dosing amount by 10% - 20% on the basis of the first carbon source dosing amount as the second carbon source dosing amount. According to the carbon source dosing point and the second carbon source dosing amount, control the carbon source dosing device to perform corresponding dosing operations.

8. The control method for adding carbon source in sewage treatment according to claim 6, characterized in that: After real-time monitoring the sludge parameters of the biochemical reaction tank, the following steps are also included: If the sludge concentration is greater than the upper limit of the third preset interval and the sludge volume index is less than the lower limit of the fourth preset interval, reduce the carbon source dosing amount by 10% - 15% on the basis of the first carbon source dosing amount as the third carbon source dosing amount. According to the carbon source dosing point and the third carbon source dosing amount, control the carbon source dosing device to perform corresponding dosing operations.

9. The control method for adding carbon source in sewage treatment according to claim 1, characterized in that: This method also includes the following steps: Real-time calculate the influent load rate and the treatment cost, and the treatment cost includes the carbon source cost and the pump energy consumption of the carbon source dosing device. If the influent load rate is greater than the first preset load rate and the treatment cost is greater than the first preset cost, the first revised effluent water quality standard is enabled, where the limit value of the key index of the first revised effluent water quality standard is wider than the corresponding limit value of the preset effluent water quality standard; if the influent load rate is less than the second preset load rate and the treatment cost is less than the second preset cost, the second revised effluent water quality standard is enabled, where the limit value of the key index of the second revised effluent water quality standard is tighter than the corresponding limit value of the preset effluent water quality standard.

10. The control method for adding carbon source in sewage treatment according to claim 1, characterized in that: Before the control carbon source dosing device performs the corresponding dosing operation, the following steps are further included: Real-time monitor the extracellular electron transfer rate of microorganisms in the biochemical reaction tank, and judge the metabolic stage of the microorganisms according to the extracellular electron transfer rate, where the metabolic stage includes a metabolic trough period and a metabolic peak period; The control carbon source dosing device performs the corresponding dosing operation, including the following steps: In the metabolic trough period, control the carbon source dosing device to suspend carbon source dosing and start low-frequency pulsed aeration; in the metabolic peak period, control the carbon source dosing device to perform the corresponding dosing operation in a high-frequency intermittent dosing mode.

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