A method for controlling carbon source addition in sewage treatment

Abstract

The present application provides a control method for adding a carbon source to sewage treatment, which relates to the technical field of sewage treatment, comprising the following steps: obtaining water inlet parameters of the sewage to be treated and process parameters of the treatment section, the water inlet parameters including chemical oxygen demand, total nitrogen, total phosphorus and flow rate, and the process parameters including phosphate concentration at the end of the anaerobic tank, nitrate concentration at the end of the anoxic tank, total nitrogen and chemical oxygen demand of the denitrification filter inlet; dynamically calculating and predicting the carbon-nitrogen ratio and the carbon-phosphorus ratio in real time based on the water inlet parameters and the process parameters; determining a carbon source addition point and a first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and a preset effluent water quality standard, the carbon source addition point including at least one of the anaerobic tank, the anoxic tank and the denitrification filter; controlling a carbon source addition device to perform corresponding addition operations based on the carbon source addition point and the first carbon source addition amount, and avoiding excessive COD caused by excessive carbon source through segmented addition and closed-loop control, thereby effectively suppressing secondary pollution.

Description

Technical Field

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

[0002] In the wastewater treatment sector, biological denitrification and phosphorus removal is a core process, and its efficiency is highly dependent on the proper dosing of carbon sources. Previously, the industry generally adopted a fixed-ratio carbon source dosing control method (dosing was based on empirically set carbon-nitrogen (C / N) and carbon-phosphorus (C / P) ratios), which lacked the ability to dynamically respond to fluctuations in influent water quality.

[0003] With technological advancements, existing technologies have begun to attempt to adopt dynamic dosing methods based on dynamic responses such as influent water quality. For example, the invention patent with publication number CN117892970A proposes a carbon source intelligent dosing method, system, and storage medium. Although this can solve the problem of excessive dosing when influent water quality fluctuates, resulting in increased effluent COD, it only targets the denitrification filter and ignores 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

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present application aims to provide a method for controlling the addition of a carbon source in sewage treatment to ensure a reasonable distribution of the carbon source and improve the phosphorus removal efficiency; the control method comprises the following steps:

[0005] Obtaining water inlet parameters of the sewage to be treated, wherein the water inlet parameters include chemical oxygen demand, total nitrogen, total phosphorus and flow rate;

[0006] Real-time monitoring of process parameters of the treatment section, including phosphate concentration at the end of the anaerobic tank, nitrate concentration at the end of the anoxic tank, total nitrogen in the influent of the denitrification filter, and chemical oxygen demand;

[0007] Dynamically calculating and predicting the carbon-nitrogen ratio and the carbon-phosphorus ratio in real time based on the influent parameters and the process parameters;

[0008] Determining a carbon source addition point and a first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and a preset effluent water quality standard, wherein the carbon source addition point includes at least one of an anaerobic tank, an anoxic tank, and a denitrification filter;

[0009] According to the carbon source addition point and the first carbon source addition amount, the carbon source addition device is controlled to perform a corresponding addition operation.

[0010] According to the technical solution provided in this application, the step of determining the carbon source addition point and the first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard includes the following steps:

[0011] If the predicted carbon-phosphorus ratio at the water inlet is less than 15, the anaerobic tank is used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition 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;

[0012] 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 water inlet is less than 4, the anoxic tank is used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition 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 interval;

[0013] 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 used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition amount required to adjust the predicted carbon-nitrogen ratio to the target carbon-nitrogen ratio.

[0014] According to the technical solution provided by the present application, the dynamic adjustment of the target carbon-phosphorus ratio and the target carbon-nitrogen ratio includes the following steps:

[0015] Monitor the influent phosphate concentration and effluent total phosphorus concentration of high-density sedimentation tanks;

[0016] If the total phosphorus concentration of the effluent exceeds the standard and the phosphate concentration of the high-density sedimentation tank inlet is high, the target carbon-phosphorus ratio is increased to the upper limit of the first preset interval; if the absolute value of the difference between the phosphate concentration of the high-density sedimentation tank inlet and the first compliance limit is less than the first preset threshold, the target carbon-phosphorus ratio is reduced to the lower limit of the first preset interval;

[0017] Monitor the total nitrogen concentration in effluent;

[0018] If the absolute value of the difference between the effluent total nitrogen concentration and the first exceeding standard limit is less than the second preset threshold, the target carbon-nitrogen ratio is increased to the upper limit of the second preset interval; if the effluent total nitrogen concentration is stable and meets the standard, the target carbon-nitrogen ratio is gradually reduced to the lower limit of the second preset interval.

[0019] According to the technical solution provided by the present application, the inlet water parameter also includes the inlet water pH value; before the carbon source dosing device is controlled to perform the corresponding dosing operation, the following steps are also included:

[0020] Select the target carbon source type according to the influent pH value: if the influent pH value is less than 6.0, use iron salt; if the influent pH value is greater than or equal to 6.0 and less than 7.0, use iron salt or aluminum salt; if the influent pH value is greater than or equal to 7.0 and less than 8.5, use aluminum salt; if the influent pH value is greater than 8.5, adjust the pH and add aluminum salt;

[0021] The controlling of the carbon source dosing device to perform the corresponding dosing operation comprises the following steps:

[0022] Controlling the carbon source adding device to add the carbon source of the target carbon source type;

[0023] The pH value after addition is monitored in real time. If the pH value exceeds the adaptability range of the selected target carbon source type and lasts for more than a preset time, the target carbon source type is switched to another carbon source type.

[0024] According to the technical solution provided by this application, after monitoring the phosphate concentration of the high-density sedimentation tank inlet and the total phosphorus concentration of the effluent, the following steps are also included:

[0025] Calculating the residual load of biological phosphorus removal based on the phosphate concentration of the high-density sedimentation tank influent, and dynamically allocating the phosphorus load ratio of biological phosphorus removal to chemical phosphorus removal in combination with the chemical phosphorus removal agent dosage coefficient;

[0026] When the biological phosphorus removal efficiency is insufficient, priority is given to increasing the target carbon-phosphorus ratio to enhance biological phosphorus removal, and the dosage of the chemical phosphorus removal agent is adjusted simultaneously.

[0027] According to the technical solution provided by the present application, after the dynamic calculation predicts the carbon-nitrogen ratio and the carbon-phosphorus ratio, and before determining the carbon source addition point and the first carbon source addition amount, the following steps are also included:

[0028] Real-time monitoring of sludge parameters in the biochemical reaction tank, including sludge concentration and sludge volume index;

[0029] The step of determining the carbon source addition point and the first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and the preset effluent water quality standard comprises the following steps:

[0030] If the sludge concentration is in the third preset range or the sludge volume index is in the fourth preset range, the carbon source addition point and the first carbon source addition amount are determined based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard.

[0031] According to the technical solution provided by the present application, after the real-time monitoring of the sludge parameters of the biochemical reaction tank, the following steps are also included:

[0032] 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, the carbon source dosage is increased by 10% to 20% on the basis of the first carbon source dosage as the second carbon source dosage;

[0033] According to the carbon source addition point and the second carbon source addition amount, the carbon source addition device is controlled to perform corresponding addition operations.

[0034] According to the technical solution provided by the present application, after the real-time monitoring of the sludge parameters of the biochemical reaction tank, the following steps are also included:

[0035] 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, reducing the carbon source dosage by 10% to 15% on the basis of the first carbon source dosage as the third carbon source dosage;

[0036] According to the carbon source addition point and the third carbon source addition amount, the carbon source addition device is controlled to perform corresponding addition operations.

[0037] According to the technical solution provided by this application, the method further includes the following steps:

[0038] Calculate the water inlet load rate and treatment cost in real time, wherein the treatment cost includes the carbon source cost and the pump energy consumption of the carbon source dosing device;

[0039] If the water inlet 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 activated, wherein the key indicator limit of the first revised effluent water quality standard is wider than the corresponding limit of the preset effluent water quality standard; if the water inlet 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 activated, wherein the key indicator limit of the second revised effluent water quality standard is tighter than the corresponding limit of the preset effluent water quality standard.

[0040] According to the technical solution provided in this application, before the carbon source dosing device is controlled to perform the corresponding dosing operation, the following steps are also included:

[0041] Real-time monitoring of the extracellular electron transfer rate of microorganisms in the biochemical reaction pool, and judging the metabolic stage of the microorganisms based on the extracellular electron transfer rate, wherein the metabolic stage includes a metabolic trough period and a metabolic peak period;

[0042] The controlling of the carbon source dosing device to perform the corresponding dosing operation comprises the following steps:

[0043] During the metabolic low period, the carbon source dosing device is controlled to suspend carbon source addition and start low-frequency pulse aeration; during the metabolic peak period, the carbon source dosing device is controlled to adopt a high-frequency intermittent dosing mode to perform corresponding dosing operations.

[0044] Compared with the existing technology, the beneficial effects of this application are: this application collects influent parameters (COD, TN, TP, flow) and process parameters (phosphate in anaerobic tank, nitrate in anoxic tank, TN / COD in denitrification filter) in real time, dynamically calculates real-time C / N and C / P, realizes multi-parameter dynamic coupling analysis, breaks through the traditional fixed ratio limit, and selects anaerobic tank (enhanced phosphorus removal), anoxic tank (enhanced nitrogen removal) or denitrification filter (deep nitrogen removal) as the injection point according to C / N, C / P and preset effluent standards, so as to realize segmented and precise supply. The preset effluent standards are also linked to real-time water quality data to dynamically adjust the target C / N and C / P ratios, forming a closed-loop control system of "monitoring-calculation-adjustment-execution." In summary, this application reduces carbon source dosage and the cost per ton of water treated through a dynamic dosing strategy. By precisely matching microbial metabolic needs and avoiding carbon source competition (such as electron donor competition between denitrifying bacteria and phosphate-accumulating bacteria), TN removal rates can be improved in wastewater with low C / N ratios (3-4) and TP removal rates in wastewater with low C / P ratios (10-15). Through staged dosing and closed-loop control, excessive carbon sources that lead to COD exceeding standards are avoided, effectively suppressing secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A flow chart of the steps of the method for controlling carbon source addition in sewage treatment provided in this application;

[0046] Figure 2 This is a cross-sectional schematic diagram of the pneumatic turbine motor device provided in this application. DETAILED DESCRIPTION

[0047] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0048] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0049] First, the mechanism of sewage treatment is described:

[0050] 1. Enhancement of biological denitrification (denitrification)

[0051] The denitrification process of wastewater treatment is usually divided into two steps:

[0052] (1) Nitrification: Ammonia nitrogen (NH3-N) is oxidized to nitrate (NO3 - ).

[0053] (2) Denitrification: Nitrate (NO3 - ) is reduced to nitrogen (N2) under anoxic conditions.

[0054] Denitrifying bacteria require organic matter (a carbon source) as an electron donor to complete their reaction. When wastewater contains insufficient organic matter (i.e., a low C / N ratio, such as in industrial wastewater or sewage diluted with rainwater), the denitrification process stalls due to a lack of carbon source, resulting in ineffective nitrate removal and excessive total nitrogen (TN) in the effluent. Adding exogenous carbon provides energy for denitrifying bacteria and promotes nitrate reduction.

[0055] 2. Enhancement of biological phosphorus removal

[0056] The biological phosphorus removal process mainly relies on the metabolism of phosphorus accumulating organisms (PAOs):

[0057] Under anaerobic conditions, polyphosphate bacteria absorb organic matter such as volatile fatty acids (VFAs) in sewage to store energy and release phosphorus; under aerobic conditions, they absorb excessive phosphorus and discharge it into the system.

[0058] If there is insufficient rapidly degradable organic matter in the wastewater, phosphate-accumulating bacteria cannot metabolize it normally, resulting in a decrease in the efficiency of biological phosphorus removal. Supplementing carbon sources can increase the activity of phosphate-accumulating bacteria and enhance the phosphorus removal effect.

[0059] 3. Maintaining microbial activity

[0060] When influent quality fluctuates (e.g., when industrial wastewater accounts for a high proportion), the environment is low temperature, sludge is aged, or the load is too low, the carbon source in the wastewater is often insufficient to maintain the basic metabolism of microorganisms, resulting in reduced microbial activity. The addition of a carbon source can provide the energy and carbon skeleton required for microbial growth, maintain sludge activity, and avoid system collapse.

[0061] 4. Commonly used carbon sources

[0062] Methanol: low cost, fast denitrification rate, but toxicity and flammability risks;

[0063] Sodium acetate: easily degradable and highly safe, but also relatively expensive;

[0064] Glucose: Suitable for small-scale systems, but may cause filamentous bacteria to swell;

[0065] Internal carbon source: Utilize sludge hydrolyzate or fermentation liquid from primary sedimentation tank (more economical and environmentally friendly).

[0066] As mentioned in the background technology, in order to solve the problems in the prior art, this application proposes a method for controlling the addition of carbon sources to sewage treatment, such as Figure 1 As shown, the following steps are included:

[0067] S1. Obtaining water parameters at the inlet end of the wastewater to be treated, wherein the water parameters include chemical oxygen demand, total nitrogen, total phosphorus, and flow rate;

[0068] S2. Real-time monitoring of process parameters of the treatment section, including phosphate concentration at the end of the anaerobic tank, nitrate concentration at the end of the anoxic tank, total nitrogen in the influent of the denitrification filter, and chemical oxygen demand;

[0069] Specifically, if Figure 2 As shown, the process flow involved in the present invention includes the following units: pretreatment stage: coarse screen → water inlet pump room → fine screen → aeration sand settling tank; biochemical treatment section: biochemical reaction tank (anaerobic section (carbon source addition) → anoxic section (carbon source addition) → aerobic section → effluent mixing); deep treatment section: secondary sedimentation tank → high-density sedimentation tank → denitrification filter (carbon source addition) → disinfection, wherein 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 deep treatment section. Monitoring parameters include: influent: total phosphorus TP, COD, total nitrogen TN, flow rate (calculation of C / N, C / P); anoxic tank: end (NO3 - High-density sedimentation tank: inlet phosphate, effluent phosphate; denitrification filter: flow rate, inlet total nitrogen (TN), inlet COD (C / N calculation); effluent: total phosphorus (TP), COD, total nitrogen (TN); Required sensors: High-precision online sensors (including sewage treatment plant inlet total phosphorus (TP), chemical oxygen demand (COD), total nitrogen (TN), and flow rate; biochemical reactor anoxic tank outlet nitrate (NO₃); denitrification filter inlet total phosphorus (TP), chemical oxygen demand (COD), total nitrogen (TN), and flow rate; denitrification filter effluent total phosphorus (TP), chemical oxygen demand (COD), total nitrogen (TN); sewage treatment plant effluent total phosphorus (TP), chemical oxygen demand (COD), and total nitrogen (TN)), with an accuracy of ±0.01 mg / L and support for real-time data upload. Controller: Industrial-grade PLC or embedded controller, supporting data acquisition, algorithm execution, and equipment control. Actuators: Variable frequency metering pump (carbon source dosing device), reagent inventory monitoring module (ultrasonic level meter). Supports switching and adding of multiple carbon sources (such as sodium acetate, methanol, composite carbon sources, etc.).

[0070] S3. Dynamically calculating and predicting the carbon-nitrogen ratio and the carbon-phosphorus ratio based on the influent parameters and the process parameters in real time;

[0071] Specifically, the predicted carbon-nitrogen ratio (predicted C / N) is calculated in real time based on 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 based on 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: combined with the NO3 -Parameters such as concentration and denitrification filter influent TN are used to predict future trends through machine learning models (such as linear regression or LSTM).

[0072] S4. Determining a carbon source addition point and a first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and a preset effluent water quality standard, wherein the carbon source addition point includes at least one of an anaerobic tank, an anoxic tank, and a denitrification filter;

[0073] Specifically, the carbon source addition point can be selected based on the traditional threshold trigger mode, or through the Carbon Source Efficiency Factor (CEF) modeling:

[0074] CEF dosing point = α, β, and γ are weighting coefficients (default values ​​are α=0.5, β=0.3, and γ=0.2), which are dynamically adjusted based on water quality fluctuations. ΔTN / TP removal rate represents the improvement in target pollutant removal efficiency after dosing. Sludge activity recovery rate is calculated using a combination of parameters such as MLSS, SVI, and EET. A regression model (such as XGBoost) is trained using historical data to predict CEF values ​​at different dosing points under varying water quality conditions. The CEF is calculated in real time for each dosing point, with the point with the highest CEF being prioritized.

[0075] Furthermore, the step of determining the carbon source addition point and the first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard comprises the following steps:

[0076] If the predicted carbon-phosphorus ratio at the water inlet is less than 15, the anaerobic tank is used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition 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;

[0077] 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 water inlet is less than 4, the anoxic tank is used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition 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 interval;

[0078] 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 used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition amount required to adjust the predicted carbon-nitrogen ratio to the target carbon-nitrogen ratio.

[0079] Furthermore, when multiple carbon source addition points are triggered at the same time, the carbon source addition amount is allocated according to the following priority: the carbon source demand of the anoxic tank is met first; the remaining carbon source is allocated to the anaerobic tank first; the denitrification filter is only used as an emergency addition; among them, the priority allocation is based on the denitrification and phosphorus removal efficiency weights of each addition point. The weights are obtained through historical data training, and the weight coefficients are dynamically adjusted to minimize the total carbon source consumption.

[0080] Specifically, the first preset interval is 15~20, and the second preset interval is 4~6. When the COD / TP of the sewage treatment plant influent is less than 15, the carbon source is added to the anaerobic pool to enhance phosphorus removal; the addition ratio is dynamically adjusted (C / P=15~20); when the NO3 at the end of the anoxic pool is - If the total nitrogen in the denitrification filter influent is >2.5 mg / L or the COD / TN ratio is <4, initiate carbon source addition to the anoxic tank to enhance denitrification and dynamically adjust the addition ratio (C / N = 4-6). If the total nitrogen in the denitrification filter influent is >15 mg / L and the COD / TN ratio is <4 mg / L, initiate emergency carbon source addition to the denitrification filter influent and dynamically adjust the addition ratio (C / N = 4-6). Monitor the effluent quality of wastewater treatment, ensuring that total phosphorus (TP) is ≤0.5 mg / L, COD is ≤50 mg / L, and total nitrogen (TN) is ≤15 mg / L.

[0081] S5. Control the carbon source adding device to perform corresponding adding operations according to the carbon source adding point and the first carbon source adding amount.

[0082] Specifically, the carbon source dosing device is configured as a variable frequency metering pump (such as the Grundfos DME series) to adjust the dosage according to PLC instructions and support multi-carbon source switching (controlled by a three-way valve).

[0083] In a preferred embodiment, the dynamic adjustment of the target carbon-phosphorus ratio and the target carbon-nitrogen ratio comprises the following steps:

[0084] Monitor the influent phosphate concentration and effluent total phosphorus concentration of high-density sedimentation tanks;

[0085] If the total phosphorus concentration of the effluent exceeds the standard and the phosphate concentration of the high-density sedimentation tank inlet is high, the target carbon-phosphorus ratio is increased to the upper limit of the first preset interval; if the absolute value of the difference between the phosphate concentration of the high-density sedimentation tank inlet and the first compliance limit is less than the first preset threshold, the target carbon-phosphorus ratio is reduced to the lower limit of the first preset interval;

[0086] Monitor the total nitrogen concentration in effluent;

[0087] If the absolute value of the difference between the effluent total nitrogen concentration and the first exceeding standard limit is less than the second preset threshold, the target carbon-nitrogen ratio is increased to the upper limit of the second preset interval; if the effluent total nitrogen concentration is stable and meets the standard, the target carbon-nitrogen ratio is gradually reduced to the lower limit of the second preset interval.

[0088] Specifically, the absolute value of the difference between the phosphate concentration of the high-density sedimentation tank inlet and the first compliance limit (the phosphate concentration of the high-density sedimentation tank inlet is less than the first compliance limit) is less than the first preset threshold, indicating that the phosphate concentration of the high-density sedimentation tank inlet is already on the edge of compliance (≤105% of the limit), and the addition of carbon source needs to be carefully controlled; the absolute value of the difference between the effluent total nitrogen concentration and the first exceeding limit is less than the second preset threshold, indicating that the water total nitrogen concentration is very close to exceeding the limit (≥95% of the limit and not exceeding the limit), and the carbon-nitrogen ratio needs to be increased to enhance denitrification.

[0089] In a preferred embodiment, after monitoring the phosphate concentration in the inlet water and the total phosphorus concentration in the outlet water of the high-density sedimentation tank, the method further includes the following steps:

[0090] Calculating the residual load of biological phosphorus removal based on the phosphate concentration of the high-density sedimentation tank influent, and dynamically allocating the phosphorus load ratio of biological phosphorus removal to chemical phosphorus removal in combination with the chemical phosphorus removal agent dosage coefficient;

[0091] When the biological phosphorus removal efficiency is insufficient, priority is given to increasing the target carbon-phosphorus ratio to enhance biological phosphorus removal, and the dosage of the chemical phosphorus removal agent is adjusted simultaneously.

[0092] Specifically, the target carbon-phosphorus ratio is dynamically adjusted by monitoring the phosphate concentration in the high-density sedimentation tank influent and calculating the residual load of biological phosphorus removal using the formula: (in, is the phosphate concentration of the high-density sedimentation tank inlet, and the coefficient 3.066 is the conversion of phosphorus molar mass. =( ...)))))))))))))))))))))))))))))))))))))))))))))))))))) .

[0093] Specifically, the target carbon-nitrogen ratio is dynamically adjusted as follows: monitor the effluent TN concentration. If it approaches the limit (e.g., TN>12 mg / L), increase the target C / N to 6 at a rate of +0.2 per hour. If the effluent TN is stable and meets the standard (≤10 mg / L for 12 consecutive hours), decrease the target C / N to 4 at a rate of -0.25 per 12 hours. Additional carbon source supplementation: When NO3 - When >2.5 mg / L, additional carbon source is required, and the additional amount = NO3 - ×2.86 / carbon source COD equivalent.

[0094] In a preferred embodiment, the influent parameter further includes an influent pH value; and before the controlling carbon source dosing device performs the corresponding dosing operation, the following steps are further included:

[0095] Select the target carbon source type according to the influent pH value: if the influent pH value is less than 6.0, use iron salt; if the influent pH value is greater than or equal to 6.0 and less than 7.0, use iron salt or aluminum salt; if the influent pH value is greater than or equal to 7.0 and less than 8.5, use aluminum salt; if the influent pH value is greater than 8.5, adjust the pH and add aluminum salt;

[0096] The controlling of the carbon source dosing device to perform the corresponding dosing operation comprises the following steps:

[0097] Controlling the carbon source adding device to add the carbon source of the target carbon source type;

[0098] The pH value after addition is monitored in real time. If the pH value exceeds the adaptability range of the selected target carbon source type and lasts for more than a preset time, the target carbon source type is switched to another carbon source type.

[0099] Specifically, if pH < 6.0: Use iron salts (such as FeCl3). Iron ions tend to form FePO4 precipitates under acidic conditions. If pH is between 6.0 and 7.0: Use iron salts or aluminum salts (such as Al2(SO4)3). Aluminum salts are more effective at phosphorus removal under neutral conditions. If pH is ≥ 7.0: Use aluminum salts (such as PAC). Al(OH)3 colloids have enhanced phosphorus adsorption under alkaline conditions. If pH is > 8.5: Add acid to adjust the pH to below 8.5 before adding aluminum salts to prevent dissolution of the Al(OH)3 colloid. Different pH values ​​affect the hydrolysis form of metal salts, which in turn affects phosphorus removal efficiency. Therefore, the type of carbon source should be selected based on actual conditions.

[0100] Furthermore, after selecting the target carbon source type according to the pH value of the influent and controlling the carbon source adding device to add the carbon source of the target carbon source type, the method further includes the following steps:

[0101] Real-time monitoring of microbial respiratory entropy (OUR) and carbon source adaptability of target carbon source types;

[0102] Specifically, the oxygen utilization rate (OUR) was measured in real time by an online respirometer, reflecting the metabolic intensity of the microorganisms (μmol O2 / g MLSS·h). The carbon source adaptability (CAI) was obtained by the formula: ;in, The removal rate refers to the change in nitrate concentration at the end of the anoxic tank, and SV30 refers to the sludge settling volume in 30 minutes, which reflects the sludge settling properties.

[0103] If the carbon source fitness is less than the first fitness and the microbial respiratory entropy is less than the first microbial respiratory entropy, the carbon source database is retrieved to match the adaptive carbon source;

[0104] Among them, the first fitness is 0.6. When it is less than 0.6, it means that the carbon source and microorganism are poorly compatible. The first microbial respiratory entropy is 1.2μmolO2 / g MLSS·h. When the first fitness is less than 0.6 and the first microbial respiratory entropy 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, respiratory entropy thresholds. Historical performance data includes post-dosing denitrification rate, sludge property changes, and costs. Adaptive carbon source matching involves selecting an adaptive carbon source from a database based on real-time salinity, microbial respiratory entropy, and carbon source compatibility. Denitrification efficiency is weighted 40%, sludge stability is weighted 30%, and cost is weighted 30%.

[0105] Specifically, adjust the amount of carbon source added to the anaerobic tank to coordinate with the addition of chemical phosphorus removal agents; monitoring parameters: monitor the COD and TP of the sewage treatment plant influent and calculate the COD / TP. When the C / P ratio of the sewage treatment plant influent is less than 15, start adding carbon source to the anaerobic tank to enhance phosphorus removal; when C / P is ≥ 15, no carbon source addition is required. Set the initial target C / P value (it is recommended to set a relatively high value initially), ΔC = (target C / P × P in )-C in If ΔC is negative (i.e., the inlet C / P is already above the target), no addition is required. Dynamically adjust the target C / P within a range of 15-20. If the phosphorus concentration after biological treatment is high (phosphate concentration at the inlet of the high-density sedimentation tank), resulting in increased chemical phosphorus removal agent usage, gradually increase the target C / P (approaching 20). If the effluent TP is stable and chemical phosphorus removal agent usage is low, the target C / P can be appropriately lowered (approaching 15) to reduce carbon source consumption.

[0106] At the same time, biological phosphorus removal and chemical phosphorus removal work together: monitor the phosphate concentration at the inlet of the high-density sedimentation tank and convert it into total phosphorus concentration. The amount of phosphorus that needs to be removed by chemical phosphorus removal is: ΔP=TP bio -0.5 mg / L, the intelligent phosphorus removal agent dosing system can calculate the amount of chemical phosphorus removal agent to be added. According to experience, every 1 mg / L of phosphorus removal 10-15 mg / L PAC needs to be added (calculated according to the type of phosphorus removal agent)

[0107] Closed-loop feedback:

[0108] Monitor the effluent quality of sewage treatment plants and adjust the dosing strategies of carbon sources and phosphorus removal agents;

[0109] The effluent total phosphorus TP is required to be ≤ 0.5 mg / L;

[0110] If the effluent TP exceeds the standard and the phosphate concentration at the inlet of the high-density sedimentation tank is high, priority should be given to increasing the target C / P (close to 20) and strengthening biological phosphorus removal.

[0111] If the phosphate concentration at the inlet of the high-density sedimentation tank is low (such as close to 0.5 mg / L), gradually reduce the target C / P and adjust the dosage of the dephosphorization agent accordingly. While ensuring that the TP of the effluent is stable and meets the standard, the dosage of the carbon source and dephosphorization agent is minimized to control the cost of dephosphorization to the lowest level.

[0112] Example 2

[0113] Based on Example 1, this example further proposes a method for further improving control accuracy, specifically including:

[0114] In a preferred embodiment, after the dynamic calculation of the predicted carbon-nitrogen ratio and the predicted carbon-phosphorus ratio, and before the determination of the carbon source addition point and the first carbon source addition amount, the following steps are further included:

[0115] Real-time monitoring of sludge parameters in the biochemical reaction tank, including sludge concentration and sludge volume index;

[0116] The step of determining the carbon source addition point and the first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and the preset effluent water quality standard comprises the following steps:

[0117] If the sludge concentration is in the third preset range or the sludge volume index is in the fourth preset range, the carbon source addition point and the first carbon source addition amount are determined based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard.

[0118] Furthermore, after the real-time monitoring of the sludge parameters of the biochemical reaction tank, the following steps are also included:

[0119] 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, the carbon source dosage is increased by 10% to 20% on the basis of the first carbon source dosage as the second carbon source dosage;

[0120] According to the carbon source addition point and the second carbon source addition amount, the carbon source addition device is controlled to perform corresponding addition operations.

[0121] Furthermore, after the real-time monitoring of the sludge parameters of the biochemical reaction tank, the following steps are also included:

[0122] 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, reducing the carbon source dosage by 10% to 15% on the basis of the first carbon source dosage as the third carbon source dosage;

[0123] According to the carbon source addition point and the third carbon source addition amount, the carbon source addition device is controlled to perform corresponding addition operations.

[0124] Specifically, the aerobic tank is the core area of ​​the activated sludge process. The state of the mixed liquor at the end directly affects the sludge return ratio and the settling efficiency of the secondary sedimentation tank. Therefore, in this example, sludge parameters are monitored at the end of the aerobic tank. The normal range of sludge concentration (MLSS) is 3000-5000 mg / L. MLSS is monitored using an online MLSS sensor (e.g., optical scattering or ultrasonic type), which is immersed in the mixed liquor at the end of the aerobic tank, one-third of the height from the tank bottom (to avoid aeration interference). The sludge volume index (SVI) is monitored using an automatic SVI analyzer (requires a sampling device). The sampling point can be located 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 SVI is 50-150 mL / g. The adjustment strategy is: if MLSS < 3000 mg / L or SVI > 150 mL / g (indicating sludge aging), increase the carbon source by 10%-20% to promote microbial growth. If MLSS>5000 mg / L and SVI<50 mL / g (indicating sludge bulking risk), reduce the carbon source by 10%~15% to avoid excessive COD loading.

[0125] In a preferred embodiment, the method further comprises the following steps:

[0126] Calculate the water inlet load rate and treatment cost in real time, wherein the treatment cost includes the carbon source cost and the pump energy consumption of the carbon source dosing device;

[0127] If the water inlet 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 activated, wherein the key indicator limit of the first revised effluent water quality standard is wider than the corresponding limit of the preset effluent water quality standard; if the water inlet 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 activated, wherein the key indicator limit of the second revised effluent water quality standard is tighter than the corresponding limit of the preset effluent water quality standard.

[0128] Specifically, treatment cost = carbon source unit price × dosage + pump energy consumption × electricity price; load factor calculation: inlet load factor = actual flow rate design flow rate × 100%; the first preset load factor can be 120%, and the second preset load factor can be 80%. If the load factor is greater than 120% and the cost is greater than the preset value, the effluent TN standard is relaxed to 18 mg / L (original standard 15 mg / L). If the load factor is less than 80% and the cost is less than the preset value, the effluent TN standard is raised to ≤10 mg / L.

[0129] Specifically, when the influent load rate exceeds a first preset load rate and the treatment cost exceeds the first preset cost, this typically occurs when the influent pollutant load is high, treatment is difficult, and operating costs are high (e.g., due to heavy rain or industrial wastewater intrusion, resulting in a sharp increase in influent concentration). In these situations, to ensure stable system operation, avoid system crashes, and control costs, relaxing effluent quality standards (i.e., allowing effluent indicators to temporarily exceed the standards within a certain range) is an emergency strategy. The goal is to prioritize preventing treatment facilities from being paralyzed, tolerating short-term water quality fluctuations, and then restoring the preset effluent quality standards after the peak load or abnormal situation passes. Optionally, the limits for total nitrogen, total phosphorus, and chemical oxygen demand in the preset effluent quality standards can be relaxed to 1.2 times, 1.15 times, and 1.1 times the original limits, respectively, to obtain a first revised effluent quality standard. Furthermore, when the influent load rate is less than a second preset load rate and the treatment cost is less than the second preset cost, this typically occurs when the influent pollutant load is low, treatment is difficult, and operating costs are low (e.g., at night or during low flow periods during the dry season). In these situations, the system has sufficient redundant processing 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. Therefore, the effluent water quality standards should be tightened. Optionally, the limits of total nitrogen, total phosphorus, and chemical oxygen demand in the preset effluent water quality standards can be tightened to 0.85 times, 0.85 times, and 0.85 times the original limits, respectively, to obtain the second revised effluent water quality standards.

[0130] In a preferred embodiment, before controlling the carbon source dosing device to perform the corresponding dosing operation, the method further includes the following steps:

[0131] Real-time monitoring of the extracellular electron transfer rate of microorganisms in the biochemical reaction pool, and judging the metabolic stage of the microorganisms based on the extracellular electron transfer rate, wherein the metabolic stage includes a metabolic trough period and a metabolic peak period;

[0132] Specifically, the extracellular electron transfer rates of microorganisms in the anaerobic tank and the anoxic tank in the biochemical reaction tank are 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 microorganism is in a 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 microorganism is in a metabolic peak period; the EET of polyphosphate bacteria (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, and the EET activity of denitrifying bacteria is higher under anoxic conditions, but it can drop to 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.

[0133] The controlling of the carbon source dosing device to perform the corresponding dosing operation comprises the following steps:

[0134] During the metabolic low period, the carbon source dosing device is controlled to suspend carbon source addition and start low-frequency pulse aeration; during the metabolic peak period, the carbon source dosing device is controlled to adopt a high-frequency intermittent dosing mode to perform corresponding dosing operations.

[0135] Specifically, the extracellular electron transfer rate (EET) reflects microbial electron transfer activity and is directly related to metabolic intensity. It is monitored using electrochemical sensors (such as microbial fuel cells). The layout is as follows: in anaerobic tanks, the electrode groups (anode + cathode) are buried in the sludge layer, with spacing of 10-20 cm. In anoxic tanks, the electrode groups are installed in the front 1 / 3 of the area in the direction of flow. During metabolic troughs, carbon source addition is suspended, and low-frequency pulsed aeration (0.1 Hz) is initiated in both the anaerobic and anoxic tanks to maintain dissolved oxygen. During metabolic peaks, a high-frequency intermittent aeration pattern is selected for the corresponding tank based on the carbon source addition point. Initiating aeration during troughs can alleviate sludge activity inhibition (e.g., increased dissolved oxygen promotes aerobic bacterial metabolism). During peaks, high-frequency carbon source addition is implemented at the previously determined carbon source addition points (e.g., if only the anoxic tank requires carbon supplementation, carbon source addition is limited to that tank, e.g., 10 seconds every 5 minutes) to match the microbial uptake rate.

[0136] Example 3

[0137] Sewage treatment plant inlet flow Q 水 =10,000 m³ / d, influent TP=15 mg / L, COD=220 mg / L, effluent total phosphorus TP≤0.5 mg / L, and the total phosphorus control target TP at the outlet of the high-density sedimentation tank is set at 0.45 mg / L; the carbon source is sodium acetate solution (COD equivalent 0.78 g COD / g, 40% solution, density 820 g / L)

[0138] COD / TP=14.67<15, start adding carbon source to the anaerobic tank to enhance phosphorus removal;

[0139] Set the initial target C / P=18 to maximize the efficiency of biological phosphorus removal

[0140] ΔC=[(target C / P×P in )-C in ]÷0.78=(18×15-220)÷0.78=64.10mg / L

[0141] Calculation of carbon source dosage: L / d=81.43L / h

[0142] High density sedimentation tank influent phosphate ( ) = 1.8 mg / L

[0143] TPbio ≈1.8÷3.066=0.587mg / L

[0144] Chemical phosphorus removal amount ΔP=0.587-0.45=0.137mg / L

[0145] The dosage of chemical phosphorus removal agent (PAC) is initially based on the removal of 1mg / L 12 mg / L PAC needs to be added

[0146] D = ΔP × k = 0.137 × 12 = 1.644 mg / L

[0147] Q PAC =D×Q 水 ÷1000=1.644×10000÷1000=16.44 L / d

[0148] Monitoring of sewage treatment plant effluent TP = 0.55 mg / L> 0.5 mg / L (still exceeding the standard)

[0149] Raise target C / P to 20 to enhance biological phosphorus removal

[0150] ΔC=[(target C / P×P in )-C in ]÷0.78=(20×15-220)÷0.78=102.56mg / L

[0151] Calculation of carbon source dosage: L / d=130.28L / h

[0152] Monitoring of phosphate in high density sedimentation tank inlet ( ) = 1.6 mg / L

[0153] TP bio ≈1.6÷3.066=0.522mg / L

[0154] Chemical phosphorus removal amount ΔP=0.522-0.45=0.072mg / L

[0155] The dosage of chemical phosphorus removal agent (PAC) is initially based on the removal of 1mg / L 12 mg / L PAC needs to be added

[0156] D = ΔP × k = 0.072 × 12 = 0.864 mg / L

[0157] Q PAC =D×Q 水 ÷1000=0.864×10000÷1000=8.64 L / d

[0158] After adjustment, the monitored sewage treatment plant effluent TP=0.45mg / L<0.5mg / L

[0159] Implementation effect data

[0160]

[0161] In summary, this embodiment achieves synergistic carbon source addition and chemical phosphorus removal in the anaerobic tank. When the influent C / P ratio is less than 15, the anaerobic tank is selected as the carbon source addition point, and the target C / P ratio is dynamically adjusted to 15-20 (a first preset range) to calculate the carbon source dosage. By monitoring the influent phosphate and effluent total phosphorus concentrations of the high-density sedimentation tank, the target C / P ratio is dynamically adjusted (for example, from 15 to 20) to enhance biological phosphorus removal. Based on the residual load of biological phosphorus removal, the phosphorus load ratio between biological and chemical phosphorus removal is dynamically allocated (for example, the PAC dosage is calculated using a formula).

[0162] Example 4

[0163] Sewage treatment plant inlet flow Q 水 =20000m³ / d, inlet TP=15mg / L, COD=300mg / l, outlet total phosphorus TP≤0.5mg / L, high-density sedimentation tank outlet set total phosphorus control target TP≤0.48mg / L

[0164] The carbon source was methanol (COD equivalent 1.5 gCOD / g, concentration 99% solution, density 790 g / L).

[0165] COD / TP=20, no carbon source needs to be added to the anaerobic tank;

[0166] High density sedimentation tank influent phosphate ( ) = 1.7 mg / L

[0167] TP bio ≈1.7÷3.066=0.554mg / L

[0168] Chemical phosphorus removal amount ΔP=0.554-0.48=0.074mg / L

[0169] The dosage of chemical phosphorus removal agent (PAC) is initially based on the removal of 1mg / L 12 mg / L PAC needs to be added

[0170] D = ΔP × k = 0.074 × 12 = 0.888 mg / L

[0171] Q PAC =D×Q 水 ÷1000=0.888×20000÷1000=17.76 L / d

[0172] Monitoring of sewage treatment plant effluent TP = 0.52 mg / L> 0.5 mg / L (still exceeding the standard)

[0173] Adjust the dosage of chemical phosphorus removal agent (PAC) to remove 1mg / L 15 mg / L PAC needs to be added

[0174] D = ΔP × k = 0.074 × 15 = 1.11 mg / L

[0175] Q PAC =D×Q 水 ÷1000=1.11×20000÷1000=22.2 L / d

[0176] After adjustment, the monitored sewage treatment plant effluent TP=0.45mg / L<0.5mg / L

[0177] Implementation effect data

[0178]

[0179] (2) Adjust the amount of carbon source added to the anoxic pool and coordinate with the emergency carbon source addition to the denitrification filter.

[0180] Priority of carbon source addition: Prioritize the anoxic tank for addition to fully utilize the pre-denitrification potential. Addition to the denitrification filter is only for emergency use and is activated when insufficient denitrification in the anoxic tank causes the filter influent TN to exceed 15mg / L.

[0181] A-Adjust the amount of carbon source added to the anoxic pool

[0182] ① Monitoring parameters

[0183] Monitor the COD and TN of the sewage treatment plant influent and calculate the COD / TN ratio.

[0184] ②Trigger conditions

[0185] Dosing of carbon source in anoxic pool: When the sewage treatment plant influent COD / TN < 4 or at the end of anoxic pool When it is >2.5mg / L, start adding carbon source to the anoxic pool to enhance denitrification;

[0186] ③Dynamically adjust target C / N

[0187] Adjustment range C / P=4~6, real-time monitoring of effluent TN concentration, and correction of target C / N value and carbon source addition coefficient through closed-loop feedback

[0188] ④Calculation of carbon source dosage

[0189] Set the initial target C / N value (it is recommended to set a high value initially, such as 5)

[0190] ΔC=(target C / N×Nin )-C in

[0191] When the end of the anoxic pool >2.5 mg / L, additional carbon source supplementation:

[0192] ΔC Extra = ×2.86 Carbon source COD equivalent (based on the theoretical carbon requirement for denitrification)

[0193] Among them, 2.86 is the amount of COD required to denitrify 1 mg of nitrate nitrogen (mg)

[0194] B-Denitrification filter emergency dosing

[0195] ① Monitoring parameters

[0196] Monitor the COD and TN of the denitrification filter inlet and calculate the COD / TN ratio.

[0197] ②Trigger conditions

[0198] Dosing of carbon source to denitrification filter: When the total nitrogen in the influent of denitrification filter is greater than 15 mg / L and the COD / TN in the influent of denitrification filter is less than 4 mg / L, start emergency dosing of denitrification filter to enhance denitrification.

[0199] ③Dynamically adjust target C / N

[0200] The adjustment range is C / P=4~6, the effluent TN concentration is monitored in real time, and the target C / N value and carbon source addition coefficient are corrected through closed-loop feedback.

[0201] ④Calculation of carbon source dosage

[0202] Set the initial target C / N value (the initial recommended setting should not be too high, such as 4.5)

[0203] ΔC=(target C / N×N in )-C in

[0204] C-Dynamic Optimization Strategy

[0205] ①Target C / N adaptive adjustment

[0206] Conditions for increase:

[0207] Outlet TN>12mg / L (close to the limit) → 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 increase rate is determined by self-learning based on feedforward and feedback data).

[0208] End of the anoxic pool >2.5 mg / L per unit time → Target C / N + a certain value (for example, initially the target C / N increases by 0.5 per hour, and the increase rate is subsequently determined by self-learning based on feedforward and feedback data).

[0209] Downgrade conditions:

[0210] If the TN of the effluent water does not exceed the set limit for a certain period of time, the target C / N ratio will be gradually reduced to 4 at a certain rate (for example, if the TN of the effluent water is ≤10 mg / L for 12 consecutive hours, the target C / N ratio will be gradually reduced to 4 at a rate of -0.25 every 12 hours).

[0211] D-closed loop feedback

[0212] Monitor the effluent quality TN of the sewage treatment plant, and the effluent total phosphorus TN should be ≤15mg / L

[0213] If the effluent TN is greater than 15 mg / L, immediately start the maximum carbon source addition (target C / N=6) and sound an alarm.

[0214] Redundant design: Set the internal control target TN ≤ 12mg / L and reserve a buffer margin of 3mg / L.

[0215] Anti-overdosage: When the carbon source dosage remains unchanged for 6 consecutive hours and the outlet TN is stable, the target C / N ratio will be automatically reduced to 4.5.

[0216] In summary, this example achieves chemical phosphorus removal as the primary method for high C / P influent. When the influent C / P is 20 (no biological phosphorus removal required), chemical phosphorus removal is fully relied upon, with the PAC dosage dynamically adjusted (from 12 mg / L to 15 mg / L). By calculating the treatment cost (PAC cost) and the influent load rate (Q = 20,000 m³ / d), the chemical phosphorus removal dosage is optimized to reduce costs.

[0217] Example 5

[0218] Sewage treatment plant inlet flow Q 水 =20,000 m³ / d, effluent quality standard TN ≤ 15 mg / L, safety margin control target TN ≤ 12 mg / L. Carbon source type and parameters: Sodium acetate (COD equivalent 0.78 g COD / g, 40% solution, density 820 g / L).

[0219] Sewage treatment influent COD=80mg / L, influent TN=25mg / L, influent COD / TN=3.2<4, start the anoxic pool carbon source addition. =3 mg / L, additional carbon source supplement.

[0220] Set the initial target C / N value = 5

[0221] Basic carbon source addition ΔC = [(target C / N×N in )-C in ] / 0.78=(5×25-80) / 0.78=57.69mg / L

[0222] Additional carbon source ΔC 额外 =Δ ×2.86 / 0.78=(3-2.5)×2.86 / 0.78=1.83mg / L

[0223] Total carbon source added = 57.69 + 1.83 = 59.52 mg / L

[0224] Sodium acetate solution dosage = 59.52 × 20000 / (0.4 × 820) = 3629.27 L / d = 151.22 L / h

[0225] Denitrification filter inlet TN=10mg / L, no need to add carbon source

[0226] The TN of the effluent is 9.5mg / L, which meets the set limit and is stable.

[0227] The TN of the effluent is ≤10 mg / L for 12 consecutive hours, and the target C / N is gradually reduced from -0.25 every 12 hours to 4.75.

[0228] Carbon source addition ΔC = [(target C / N×N in )-C in ] / 0.78=(4.75×25-80) / 0.78=49.68mg / L

[0229] End of the anoxic pool =2.6 mg / L>2.5 mg / L, additional carbon source is required.

[0230] Additional carbon source ΔC 额外 =Δ ×2.86 / 0.78=(2.6-2.5)×2.86 / 0.78=0.37mg / L

[0231] Therefore, the total carbon source added = 49.68 + 0.37 = 50.04 mg / L

[0232] Sodium acetate solution dosage = 50.04 × 20000 / (0.4 × 820) = 3051.22 L / d = 127.13 L / h

[0233] Denitrification filter inlet TN=12mg / L, no need to add carbon source

[0234] The TN of the effluent is 11.5mg / L, which meets the set limit and is stable and up to standard.

[0235] Implementation effect data

[0236]

[0237] In summary, when the influent C / N ratio is 3.2 < 4, the anoxic tank is selected as the dosing point, and the target C / N ratio is dynamically adjusted (from 5 to 4.75). The target C / N ratio is adjusted through closed-loop feedback of the effluent TN concentration (for example, gradually decreasing it after continuous compliance). The carbon source dosage can be adjusted based on sludge parameters (MLSS, SVI) (for example, increase the dosage by 10%-20% when MLSS < 3000 mg / L).

[0238] Example 6

[0239] Sewage treatment plant inlet flow Q 水 =10,000 m³ / d, effluent quality standard TN ≤ 15 mg / L, safety margin control target TN ≤ 12 mg / L. Carbon source type and parameters: methanol (COD equivalent 1.5 gCOD / g, 99% solution, density 790 g / L).

[0240] Sewage treatment influent COD=150mg / L, influent TN=40mg / L, influent COD / TN=3.75<4, start the anoxic pool carbon source addition. =2.6 mg / L, no additional carbon source is needed.

[0241] Set the initial target C / N value = 5

[0242] Basic carbon source addition ΔC = [(target C / N×N in )-C in ] / 1.5=(5×40-150) / 1.5=33.33mg / L

[0243] Additional carbon source ΔC 额外 = ×2.86 / 1.5=(2.6-2.5)×2.86 / 1.5=0.19mg / L

[0244] Total carbon source dosage = 33.33 + 0.19 = 33.52 mg / L

[0245] Methanol solution dosage = 33.52 × 10000 / (0.99 × 790) = 428.59 L / d = 17.86 L / h

[0246] Denitrification filter inlet TN=16mg / L>15mg / L, inlet COD=50mg / L, C / N=2.78<4, start denitrification filter carbon source addition

[0247] Set the initial target C / N value = 4.5

[0248] Carbon source addition ΔC = [(target C / N×N in )-C in ] / 1.5=(4.5×16-50) / 1.5=14.67mg / L

[0249] Methanol solution dosage = 14.67 × 10000 / (0.99 × 790) = 187.57 L / d = 7.82 L / h

[0250] The TN of the effluent is 14mg / L, which meets the set limit and is stable.

[0251] Implementation effect data

[0252]

[0253] In summary, when the denitrification filter influent TN is greater than 15 mg / L and the C / N ratio is less than 4, the denitrification filter is triggered to dosing. The carbon source type is selected based on the influent pH (methanol is suitable in the neutral pH range), and the pH after dosing is monitored in real time. Subsequently, by monitoring the microbial extracellular electron transfer rate (EET), a high-frequency intermittent dosing mode can be adopted during peak metabolic periods.

[0254] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, they can also make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A method for controlling carbon source addition in sewage treatment, characterized in that: The process flow of this method includes the following units connected in sequence: A pretreatment unit, the pretreatment unit comprising a coarse screen, a water inlet pump room, a fine screen, and an aeration and grit chamber connected in sequence; A biochemical treatment unit, comprising an anaerobic tank, an anoxic tank and an aerobic tank connected in sequence; A deep treatment unit, comprising a secondary sedimentation tank, a high-density sedimentation tank, a denitrification filter, and a disinfection tank connected in sequence; The method comprises the following steps: Obtaining water parameters at the water inlet of the sewage to be treated, wherein the water parameters include chemical oxygen demand, total nitrogen, total phosphorus and flow rate; Real-time monitoring of process parameters of the treatment section, including phosphate concentration at the end of the anaerobic tank, nitrate concentration at the end of the anoxic tank, total nitrogen in the influent of the denitrification filter, and chemical oxygen demand; Dynamically calculating and predicting the carbon-nitrogen ratio and the carbon-phosphorus ratio in real time based on the influent parameters and the process parameters; Determining a carbon source addition point and a first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and a preset effluent water quality standard, wherein the carbon source addition point includes at least one of an anaerobic tank, an anoxic tank, and a denitrification filter; According to the carbon source addition point and the first carbon source addition amount, controlling the carbon source addition device to perform a corresponding addition operation; The step of determining the carbon source addition point and the first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and the preset effluent water quality standard comprises the following steps: If the predicted carbon-phosphorus ratio at the water inlet is less than 15, the anaerobic tank is used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition 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 water inlet is less than 4, the anoxic tank is used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition 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 interval; 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 used as the carbon source addition point, and the first carbon source addition amount is the first carbon source addition amount required to adjust the predicted carbon-nitrogen ratio to the target carbon-nitrogen ratio.

2. The method for controlling carbon source addition in sewage treatment according to claim 1, characterized in that: The dynamic adjustment of the target carbon-phosphorus ratio and the target carbon-nitrogen ratio comprises the following steps: Monitor the influent phosphate concentration and effluent total phosphorus concentration of high-density sedimentation tanks; If the total phosphorus concentration of the effluent exceeds the standard and the phosphate concentration of the high-density sedimentation tank inlet is high, the target carbon-phosphorus ratio is increased to the upper limit of the first preset interval; if the absolute value of the difference between the phosphate concentration of the high-density sedimentation tank inlet and the first compliance limit is less than the first preset threshold, the target carbon-phosphorus ratio is reduced to the lower limit of the first preset interval; Monitor the total nitrogen concentration in effluent; If the absolute value of the difference between the effluent total nitrogen concentration and the first exceeding standard limit is less than the second preset threshold, the target carbon-nitrogen ratio is increased to the upper limit of the second preset interval; if the effluent total nitrogen concentration is stable and meets the standard, the target carbon-nitrogen ratio is gradually reduced to the lower limit of the second preset interval.

3. The method for controlling carbon source addition in sewage treatment according to claim 1, characterized in that: The inlet water parameter also includes the inlet water pH value; before the control carbon source dosing device performs the corresponding dosing operation, the following steps are also included: Select the target carbon source type according to the influent pH value: if the influent pH value is less than 6.0, use iron salt; if the influent pH value is greater than or equal to 6.0 and less than 7.0, use iron salt or aluminum salt; if the influent pH value is greater than or equal to 7.0 and less than 8.5, use aluminum salt; if the influent pH value is greater than 8.5, adjust the pH and add aluminum salt; The controlling of the carbon source dosing device to perform the corresponding dosing operation comprises the following steps: Controlling the carbon source adding device to add the carbon source of the target carbon source type; The pH value after addition is monitored in real time. If the pH value exceeds the adaptability range of the selected target carbon source type and lasts for more than a preset time, the target carbon source type is switched to another carbon source type.

4. The method for controlling carbon source addition in sewage treatment according to claim 2, characterized in that: After monitoring the phosphate concentration of the high-density sedimentation tank inlet and the total phosphorus concentration of the effluent, the method further comprises the following steps: Calculating the residual load of biological phosphorus removal based on the phosphate concentration of the high-density sedimentation tank influent, and dynamically allocating the phosphorus load ratio of biological phosphorus removal to chemical phosphorus removal in combination with the chemical phosphorus removal agent dosage coefficient; When the biological phosphorus removal efficiency is insufficient, priority is given to increasing the target carbon-phosphorus ratio to enhance biological phosphorus removal, and the dosage of the chemical phosphorus removal agent is adjusted simultaneously.

5. The method for controlling carbon source addition in sewage treatment according to claim 1, characterized in that: After dynamically calculating and predicting the carbon-nitrogen ratio and the carbon-phosphorus ratio, and before determining the carbon source addition point and the first carbon source addition amount, the following steps are further included: Real-time monitoring of sludge parameters in the biochemical reaction tank, including sludge concentration and sludge volume index; The step of determining the carbon source addition point and the first carbon source addition amount based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio, and the preset effluent water quality standard comprises the following steps: If the sludge concentration is in the third preset range or the sludge volume index is in the fourth preset range, the carbon source addition point and the first carbon source addition amount are determined based on the predicted carbon-nitrogen ratio, the predicted carbon-phosphorus ratio and the preset effluent water quality standard.

6. The method for controlling carbon source addition in sewage treatment according to claim 5, characterized in that: After the real-time monitoring of 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, the carbon source dosage is increased by 10% to 20% on the basis of the first carbon source dosage as the second carbon source dosage; According to the carbon source addition point and the second carbon source addition amount, the carbon source addition device is controlled to perform corresponding addition operations.

7. The method for controlling carbon source addition in sewage treatment according to claim 5, characterized in that: After the real-time monitoring of 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, reducing the carbon source dosage by 10% to 15% on the basis of the first carbon source dosage as the third carbon source dosage; According to the carbon source addition point and the third carbon source addition amount, the carbon source addition device is controlled to perform corresponding addition operations.

8. The method for controlling carbon source addition in sewage treatment according to claim 1, characterized in that: The method further comprises the following steps: Calculate the water inlet load rate and treatment cost in real time, wherein the treatment cost includes the carbon source cost and the pump energy consumption of the carbon source dosing device; If the water inlet 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 activated, wherein the key indicator limit of the first revised effluent water quality standard is wider than the corresponding limit of the preset effluent water quality standard; if the water inlet 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 activated, wherein the key indicator limit of the second revised effluent water quality standard is tighter than the corresponding limit of the preset effluent water quality standard.

9. The method for controlling carbon source addition in sewage treatment according to claim 1, characterized in that: Before controlling the carbon source dosing device to perform the corresponding dosing operation, the method further includes the following steps: Real-time monitoring of the extracellular electron transfer rate of microorganisms in the biochemical reaction pool, and judging the metabolic stage of the microorganisms based on the extracellular electron transfer rate, wherein the metabolic stage includes a metabolic trough period and a metabolic peak period; The controlling of the carbon source dosing device to perform the corresponding dosing operation comprises the following steps: During the metabolic low period, the carbon source dosing device is controlled to suspend carbon source addition and start low-frequency pulse aeration; during the metabolic peak period, the carbon source dosing device is controlled to adopt a high-frequency intermittent dosing mode to perform corresponding dosing operations.

Images