Accurate carbon source adding method and system for sewage denitrification system

Abstract

The invention provides an accurate carbon source adding method and system for a sewage denitrification system. The sewage denitrification system comprises at least one stage of AO treatment system, each stage of AO treatment system comprises an anaerobic tank and an aerobic tank which are connected in sequence; the accurate carbon source adding method comprises the following steps: collecting the inlet water TN concentration, the inlet water COD concentration and the instantaneous inlet water flow of the anaerobic tank; and calculating the dosing concentration and dosage of the preposed carbon source added into the anaerobic tank based on the collected TN concentration and COD concentration of the inlet water and the instantaneous inlet water flow. According to the accurate carbon source adding method and system for the sewage denitrification system, the situation that a carbon source agent is excessively added due to irregular fluctuation of the inflow water amount and the total nitrogen concentration can be reduced through the accurate carbon source adding method, accurate adding of the carbon source agent is achieved, and therefore the agent utilization rate is effectively increased; and the cost of the carbon source medicament is controlled and reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a precise carbon source dosing method and system for a sewage denitrification system. Background Art

[0002] In the urban water treatment process, the denitrification process mainly sets up anoxic tanks, denitrification filters, etc., and produces N2 through denitrification to achieve the purpose of denitrification. When the carbon source in the sewage cannot meet the denitrification demand or the emission standards are high, it is necessary to add an external carbon source.

[0003] At present, there are two ways to add carbon sources: manual addition and intelligent addition. Under the pressure of environmental protection policies, in order to ensure that the effluent meets the requirements, most manual dosing methods use constant overdosing, delayed overdosing, fluctuating impulse dosing and other overdosing methods, which control the total nitrogen in the effluent to a level far below the effluent standard, resulting in a waste of carbon source agent addition costs and unstable effluent indicators.

[0004] Although some sewage treatment plants adopt intelligent dosing to adjust the dosage in real time according to the influent flow, the influent water quality of domestic sewage treatment plants fluctuates greatly, and there is still a risk of exceeding the standard by adjusting the flow rate alone. A small number of sewage treatment plants adopt the method of adjusting the dosage in real time according to the total nitrogen load, but the total nitrogen in the influent has a strong lag, and the nitric nitrogen entering the anoxic zone is also affected by the internal and external return flow, and the control system has a weak impact resistance. Summary of the invention

[0005] Based on the above technical problems, the present invention provides a precise carbon source addition method and system for a sewage denitrification system. The precise carbon source addition method can reduce the excessive addition of carbon source agents caused by irregular fluctuations in influent water volume and total nitrogen concentration, and realize the precise addition of carbon source agents, thereby effectively improving the utilization rate of the agents and achieving the control and reduction of the cost of carbon source agents.

[0006] The present invention proposes a precise carbon source dosing method for a sewage denitrification system, wherein the sewage denitrification system comprises at least one level of AO treatment system; each level of AO treatment system comprises an anaerobic tank and an aerobic tank connected in sequence;

[0007] The precise carbon source addition method comprises:

[0008] S1, collecting the influent TN concentration, influent COD concentration and instantaneous influent flow rate of the anaerobic tank;

[0009] S2, based on the influent TN concentration, influent COD concentration and instantaneous influent flow collected in step S1, calculate the concentration and amount of the pre-carbon source added to the anaerobic tank;

[0010] Among them, the calculation formulas for the concentration and amount of the pre-carbon source are:

[0011] Pre-carbon source dosing concentration = K n *{[(TN1 进水 -TN2 出水 )*C / N-(COD 进水 *B / C)] / COD 当量};

[0012] Pre-carbon source dosage = pre-carbon source dosage concentration * Q1 进水 / C 溶药 ;

[0013] In the above formula, the unit of the concentration of the pre-carbon source is mg / L, and the unit of the pre-carbon source dosage is m 3 / h; K n is the set coefficient value; TN1 进水 TN2 is the total nitrogen concentration of the anaerobic tank influent, in mg / L; 出水 It is the total nitrogen concentration of the effluent set according to the effluent requirements of the AO treatment system, in mg / L; C / N is the ratio of organic carbon to effective fixed nitrogen in the set sewage; COD 进水 is the COD concentration of the anaerobic tank influent, in mg / L; B / C is the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) in the sewage; COD 当量 Q1 is the amount of oxygen required after all the carbon source per unit volume or unit mass is oxidized; 进水 is the instantaneous flow rate of anaerobic tank inlet, in m 3 / h; C 溶药 is the prepared concentration of the carbon source used.

[0014] In the present invention, the calculation of the concentration and dosage of the pre-carbon source is linked to the inlet water quality and the inlet flow rate. The carbon source dosage changes with the change of the inlet water quality and the inlet flow rate. The inlet TN concentration, the outlet TN concentration, the inlet COD concentration, the inlet flow rate and other parameters are detected by periodic sampling of online instruments. The carbon source dosage is calculated by an algorithm, and the operating frequency of the carbon source dosing pump is controlled by the carbon source dosage, thereby changing the carbon source dosage during the process operation.

[0015] Preferably, C / N is initially set to 5.

[0016] Preferably, in step S2, K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1,

[0017]

[0018] In the above formula, n is the number of times the online monitoring equipment takes samples.

[0019] In the present invention, the pre-denitrification dosing adjustment is controlled by the pre-carbon source dosing concentration. A coefficient is added to the pre-carbon source dosing concentration formula. The pre-carbon source dosing is adjusted by the coefficient change. The coefficient change is obtained by comparing the pre-effluent TN index and the pre-actual effluent TN concentration.

[0020] When the actual TN concentration of the front water outlet is greater than the TN index of the front water outlet, the program determines that the front carbon source dosing concentration is insufficient, adjusts the coefficient, and increases it by 7%, that is, coefficient*1.07=new coefficient. Substitute the new coefficient into the calculation formula of the front carbon source dosing concentration to obtain the new front carbon source dosing concentration, thereby adjusting the front carbon source dosing amount;

[0021] When the actual TN concentration of the front effluent is less than the TN index of the front effluent, it is determined that too much carbon source is added, and the total carbon source is reduced by 3%, that is: coefficient * 0.97 = new coefficient. The new coefficient is brought into the dosing formula to calculate the dosage.

[0022] Preferably, in step S2, when the calculated pre-carbon source dosage is ≤0, the addition of the pre-carbon source is stopped; when the calculated pre-carbon source dosage is >0 and < the lower limit of the flow rate of the pre-carbon source dosing pump, the pre-carbon source dosing pump starts the intermittent dosing mode; when the calculated pre-carbon source dosage is > the upper limit of the flow rate of the pre-carbon source dosing pump, the pre-carbon source dosing pump maintains full frequency operation and triggers an alarm to reduce the water intake.

[0023] In the present invention, when the formula calculates that the amount of the pre-carbon source added is less than or equal to 0, the pre-carbon source adding device stops adding the carbon source;

[0024] When the formula calculates that the amount of the front carbon source added is greater than 0 and less than the lower limit of the carbon source dosing pump flow rate, the front carbon source dosing pump starts the intermittent dosing mode to avoid waste of medicine;

[0025] When the formula calculates that the amount of pre-carbon source added is greater than the upper limit of the carbon source dosing pump flow rate, the two pre-carbon source dosing pumps are enabled to dosing at the same time to avoid exceeding the limit due to lack of reagents;

[0026] When the formula calculates that the amount of pre-carbon source added is greater than the upper limit of the flow rate of the two pre-carbon source dosing pumps, the two pre-carbon source dosing pumps maintain full frequency operation and trigger an alarm at the same time, reminding the on-site operating personnel to pay attention to the system operation. If there is a risk of exceeding the standard, try to reduce the water intake;

[0027] When the inlet TN concentration, pre-outlet TN concentration, inlet COD concentration, and inlet flow rate parameter values ​​collected by the system show abnormal fluctuations, the system alarm is triggered to remind on-site operators to review the abnormal parameters.

[0028] Preferably, step S2 further includes adjusting the reserved buffer time of the pre-carbon source dosage;

[0029] Pre-carbon source reserved buffer time = t0 + V / Q1 进水 ;

[0030] In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 .

[0031] In the present invention, during the carbon source dosing adjustment process, the dosing adjustment time node is considered after the residence time of each process and the change of the influent water quality, the buffer time is accurately controlled, and the carbon source dosing amount is adjusted in time;

[0032] Specifically, the precise dosing system collects data on the quality and quantity of incoming water, and the dosage is first associated with the water volume to ensure accurate dosing of the agent; on this basis, the impact of each process residence time on the dosage adjustment time is considered, and the dosage adjustment buffer time is considered.

[0033] Preferably, the sewage denitrification system further comprises a deep treatment system, and the deep treatment system comprises a denitrification deep bed filter or a deep treatment anaerobic tank;

[0034] Preferably, the carbon source precise dosing method further comprises:

[0035] S3, collecting the TN concentration of the effluent of the AO treatment system and the instantaneous water inflow of the denitrification deep bed filter or the deep treatment anaerobic tank;

[0036] S4, based on the effluent TN concentration and instantaneous inlet flow rate collected in step S3, calculating the concentration and amount of post-carbon source added to the denitrification deep bed filter or the deep treatment anaerobic tank;

[0037] Among them, the calculation formulas for the post-carbon source dosing concentration and the post-carbon source dosing amount are:

[0038] Post-carbon source dosing concentration = K n *{[(TN3 出水 -TN4 出水 )*C / N] / COD 当量};

[0039] Post-carbon source dosage = carbon source dosage concentration * Q2 进水 / C 溶药 ;

[0040] In the above formula, the unit of post-carbon source dosing concentration is mg / L, and the unit of post-carbon source dosing amount is m 3 / h; K n is the set coefficient value; TN3 出水 TN4 is the total nitrogen concentration of the effluent from the AO treatment system, in mg / L;出水 The total nitrogen concentration of the effluent is set according to the effluent requirements of the deep treatment system, in mg / L, Q2 进水 is the instantaneous flow rate of water in the denitrification deep bed filter or deep treatment anaerobic tank, in m 3 / h;

[0041] Preferably, C / N is initially set to 5.

[0042] In the present invention, the post-denitrification dosing algorithm is designed to be linked with the pre-denitrification effluent water quality and inlet flow rate, and the carbon source dosage changes with the changes in the pre-denitrification effluent water quality and inlet flow rate; the pre-effluent TN concentration, inlet flow rate and other parameters are detected by online instrument periodic sampling, and the carbon source dosage is calculated by the algorithm, and the operating frequency of the carbon source dosing pump is controlled by the carbon source dosage, thereby changing the carbon source dosage during the process operation.

[0043] Among them, the post-carbon source dosing concentration is obtained by the water quality correlation formula, the inlet flow rate is the current instantaneous inlet flow rate, which is measured by the flow meter, and the dissolved drug concentration is the prepared concentration of the carbon source agent.

[0044] Preferably, in step S4, K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1,

[0045]

[0046] In the above formula, n is the number of times the online monitoring equipment takes samples.

[0047] In the present invention, the post-denitrification dosing adjustment is controlled by the post-carbon source dosing concentration. A coefficient is added to the post-carbon source dosing concentration formula. The coefficient change adjusts the post-denitrification dosing. The coefficient change is obtained by comparing the effluent TN index and the post-actual effluent TN concentration.

[0048] When the actual effluent TN concentration of the post-treatment water is greater than the effluent TN index, the program determines that the pre-treatment carbon source dosing concentration is insufficient, and adjusts the coefficient by 7%, that is, coefficient*1.07=new coefficient. The new coefficient is brought into the calculation formula of the post-treatment carbon source dosing concentration to obtain the new post-treatment carbon source dosing concentration, thereby adjusting the post-treatment carbon source dosing amount.

[0049] When the actual effluent TN concentration is less than the effluent TN index, it is determined that too much carbon source is added, and the total carbon source is reduced by 3%, that is: coefficient * 0.97 = new coefficient. The new coefficient is brought into the dosing formula to calculate the dosage.

[0050] Preferably, in step S4, when the calculated post-carbon source dosage is ≤0, the addition of the post-carbon source is stopped; when the calculated post-carbon source dosage is >0 and < the lower limit of the post-carbon source dosing pump flow rate, the post-carbon source dosing pump starts the intermittent dosing mode; when the calculated post-carbon source dosage is > the upper limit of the post-carbon source dosing pump flow rate, the post-carbon source dosing pump maintains full frequency operation and triggers an alarm to reduce the water intake.

[0051] In the present invention, when the formula calculates that the amount of post-carbon source added is less than or equal to 0, the post-carbon source adding device stops adding the carbon source;

[0052] When the formula calculates that the amount of post-carbon source dosing is greater than 0 and less than the lower limit of the carbon source dosing pump flow rate, the post-carbon source dosing pump starts the intermittent dosing mode to avoid waste of medicine;

[0053] When the formula calculates that the amount of post-carbon source dosing is greater than the upper limit of the carbon source dosing pump flow rate, the two post-carbon source dosing pumps are enabled to dosing at the same time to avoid exceeding the standard due to lack of reagents;

[0054] When the values ​​of the pre-outlet TN concentration, outlet TN concentration, and inlet flow rate parameters collected by the system show abnormal fluctuations, the system alarm is triggered to remind the on-site operating personnel to review the abnormal parameters.

[0055] Preferably, step S2 further includes adjusting the reserved buffer time of the post-carbon source dosage;

[0056] Post-carbon source reserved buffer time = t0 + V / Q2 进水 ;

[0057] In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 .

[0058] The present invention also provides a precise carbon source dosing system for a sewage denitrification system, which adopts the precise carbon source dosing method mentioned above. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a schematic diagram of the structure of the sewage denitrification system described in Example 1;

[0060] Figure 2 The curves showing the change of the daily average concentration of TN over time during the operation of the sewage denitrification system described in Example 1 and Comparative Example 1;

[0061] Figure 3 The curve of the amount of carbon source added per kilogram of TN removed over time during the operation of the sewage denitrification system described in Example 1 and Comparative Example 1;

[0062] Figure 4This is a schematic diagram of the structure of the sewage denitrification system described in Example 2;

[0063] Figure 5 The curve of the change of the daily average concentration of TN over time during the operation of the sewage denitrification system described in Example 2 and Comparative Example 2;

[0064] Figure 6 The curve of the change of the dosage of carbon source per kilogram of TN removed over time during the operation of the sewage denitrification system described in Example 2 and Comparative Example 2. DETAILED DESCRIPTION

[0065] Hereinafter, the present invention will describe the technical solution in detail through specific embodiments, but it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention.

[0066] Example 1

[0067] This embodiment proposes a method for accurately adding a carbon source to a wastewater denitrification system. Figure 1 The sewage denitrification system includes a coarse grid well, a fine grid well, an aerated grit chamber, a secondary AO biochemical tank, a radial flow type secondary sedimentation tank, a high-efficiency sedimentation tank, a denitrification deep bed filter and a contact disinfection tank connected in sequence;

[0068] The aerated grit chamber receives sewage from the coarse grid well and the fine grid well after coarse separation. After aeration and grit, the inorganic particles such as silt and impurities with high density in the sewage are removed. The effluent from the aerated grit chamber enters the secondary AO biochemical tank, which includes an anaerobic tank and an aerobic tank. The dosing room uses a carbon source dosing pump to add a pre-placed carbon source into the anaerobic tank for denitrification. After that, the effluent from the AO biochemical tank enters the radial flow type peripheral inlet and outlet secondary sedimentation tank. The mud and water are separated in the radial flow type peripheral inlet and outlet secondary sedimentation tank, and part of the sludge is returned to the AO biochemical tank through the sludge return pump The effluent from the secondary sedimentation tank enters the high-efficiency sedimentation tank, and part of the precipitated sludge is discharged as residual sludge. The supernatant from the secondary sedimentation tank enters the high-efficiency sedimentation tank. The dosing room uses a dosing pump to add PAC and PAM flocculants into the high-efficiency sedimentation tank for flocculation. The effluent from the high-efficiency sedimentation tank enters the denitrification deep bed filter. The dosing room uses a carbon source dosing pump to add a post-carbon source into the denitrification deep bed filter for deep denitrification and denitrification. The effluent from the denitrification deep bed filter enters the contact disinfection tank. The dosing room uses a dosing pump to add sodium hypochlorite into the contact disinfection tank for disinfection, and finally it is discharged into the river.

[0069] During the above operation, the method of adding the front carbon source and the rear carbon source specifically includes:

[0070] (1) The influent TN concentration, influent COD concentration and instantaneous influent flow rate of the anaerobic tank are detected by online instrument periodic sampling, which is recorded as TN1 进水 、COD 进水 and Q1 进水 ;

[0071] (2) Calculate the concentration and amount of the pre-carbon source added to the anaerobic tank according to the following formula:

[0072] Pre-carbon source dosing concentration = K n *{[(TN1 进水 -TN2 出水 )*C / N-(COD 进水 *B / C)] / COD 当量};

[0073] In the above formula, the unit of the concentration of the pre-carbon source is mg / L, and the unit of the pre-carbon source dosage is m 3 / h; K n is the set coefficient value; TN1 进水 The unit is mg / L; TN2 出水 is the total nitrogen concentration of the effluent set according to the effluent requirements of the secondary AO biochemical pool, in mg / L; C / N is the ratio of organic carbon to effective fixed nitrogen in the set sewage, initially set to 5; COD 进水 The unit is mg / L; B / C is the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) in sewage; COD 当量 Q1 is the amount of oxygen required after all the carbon source per unit volume or unit mass is oxidized; 进水 Unit: m 3 / h; C 溶药 is the prepared concentration of the carbon source used;

[0074] In step (2), K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1,

[0075]

[0076] In the above formula, n is the number of times the online monitoring equipment takes samples;

[0077] In step (2), when the calculated pre-carbon source dosage is ≤0, the pre-carbon source is stopped; when the calculated pre-carbon source dosage is greater than 0 and less than the lower limit of the pre-carbon source dosing pump flow rate, the pre-carbon source dosing pump starts the intermittent dosing mode; when the calculated pre-carbon source dosage is greater than the upper limit of the pre-carbon source dosing pump flow rate, the pre-carbon source dosing pump keeps running at full frequency and triggers an alarm to reduce the water intake;

[0078] Among them, it also includes the reserved buffer time for adjusting the amount of pre-carbon source added;

[0079] Pre-carbon source reserved buffer time = t0 + V / Q1 进水 ;

[0080] In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 ;

[0081] (3) Collect the TN concentration of the effluent from the secondary AO biochemical pool and the instantaneous inlet flow rate of the denitrification deep bed filter, recorded as TN3 出水 and Q2 进水 ;

[0082] (4) Calculate the concentration and amount of post-carbon source added to the denitrification deep bed filter according to the following formula:

[0083] Post-carbon source dosing concentration = K n *{[(TN3 出水 -TN4 出水 )*C / N] / COD 当量};

[0084] Post-carbon source dosage = carbon source dosage concentration * Q2 进水 / C 溶药 ;

[0085] In the above formula, the unit of post-carbon source dosing concentration is mg / L, and the unit of post-carbon source dosing amount is m 3 / h; K n is the set coefficient value; TN3 出水 The unit is mg / L; TN4 出水 The total nitrogen concentration of the effluent is set according to the effluent requirements of the denitrification deep bed filter, in mg / L, Q2 进水 Unit: m 3 / h;

[0086] In step (4), K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1,

[0087]

[0088] In the above formula, n is the number of times the online monitoring equipment takes samples;

[0089] In step (4), when the calculated amount of post-carbon source added is ≤0, the addition of post-carbon source is stopped; when the calculated amount of post-carbon source added is >0 and < the lower limit of the flow rate of the post-carbon source dosing pump, the post-carbon source dosing pump starts the intermittent dosing mode; when the calculated amount of post-carbon source added is > the upper limit of the flow rate of the post-carbon source dosing pump, the post-carbon source dosing pump keeps running at full frequency and triggers an alarm to reduce the water intake;

[0090] Among them, it also includes the reserved buffer time for adjusting the amount of post-carbon source addition;

[0091] Post-carbon source reserved buffer time = t0 + V / Q2 进水 ;

[0092] In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 .

[0093] In this embodiment, when adding carbon source in the sewage denitrification system, two carbon source dosing points are involved, namely, the front carbon source dosing point, which is located at the water inlet of the secondary AO biochemical reaction tank, and the rear carbon source dosing point, which is located at the water inlet of the denitrification deep bed filter; the type of sewage to be treated is domestic sewage, and the designed water inlet is 30,000 m 3 / d, the designed influent water quality standard is BOD≤180mg / L, COD≤350mg / L, total nitrogen≤43mg / L, ammonia nitrogen≤35mg / L, total phosphorus≤4mg / L, SS≤250mg / L;

[0094] Comparative Example 1

[0095] This comparative example also proposes a method for adding a carbon source to a sewage denitrification system. The sewage denitrification system and the carbon source dosing point are the same as those in Example 1, except that the carbon source addition method is based on the experience of on-site operators.

[0096] refer to Figure 2 It can be seen that the inlet TN of Example 1 fluctuates between 16.46-27.79 mg / L, with an average of 21.36 mg / L, and the outlet TN fluctuates between 1.77-8.11 mg / L, with an average of 5.66 mg / L. The TN removal rate of Example 1 is 73.52%; the inlet TN of Comparative Example 1 fluctuates between 14.86-32.45 mg / L, with an average of 23.33 mg / L, and the outlet TN fluctuates between 4.51-9.01 mg / L, with an average of 7.05 mg / L. The TN removal rate of Comparative Example 1 is 69.78%; By comparison, it can be seen that the dosing method of Example 1 has a better TN removal effect.

[0097] refer to Figure 3 It can be seen that the average carbon source consumption per kilogram of total nitrogen removed in Example 1 is 5.93Kg, and the average carbon source consumption in Comparative Example 1 is 8.96Kg. Example 1 saves 34% in the use of reagents relative to Comparative Example 1, showing higher efficiency; and the average data variance of the carbon source consumption per kilogram of total nitrogen removed in Example 1 is 1.57, and the average data variance of the carbon source consumption per kilogram of total nitrogen removed in Comparative Example 1 is 6.96. By comparison, it can be seen that the dosing situation in Example 1 is relatively stable.

[0098] Example 2

[0099] This embodiment proposes a method for accurately adding a carbon source to a wastewater denitrification system. Figure 4 , the sewage denitrification system includes a grid, a Bionet-A reaction system (primary A), a Bionet-O reaction system (O), a Bionet-A reaction system (secondary A), a micromagnetic flocculation reaction system and a magnetic microfiltration separation system;

[0100] The raw sewage enters the primary A pool after filtering large suspended solids through the screen. The dosing room adds the front carbon source through the carbon source dosing pump into the primary A pool for denitrification and denitrification. Then the effluent from the primary A pool enters the O pool. After consuming most of the ammonia nitrogen and part of the COD, a nitrate reflux system is set at the outlet of the O pool to return most of the nitrate to the primary A pool. The effluent from the O pool enters the secondary A pool again. The dosing room adds the rear carbon source through the carbon source dosing pump into the secondary A pool for deep denitrification through anoxic denitrification. The effluent from the secondary A pool enters the micromagnetic flocculation reaction system. The dosing room adds PA through the dosing pump The flocculants of C and PAM enter the micro-magnetic flocculation reaction system. The pollutants in the micro-magnetic flocculation reaction system gather together with the magnetic medium under the action of the flocculant in the coagulation reaction to form magnetic flocs. The resulting mud-water mixture enters the magnetic microfiltration separation system together. The magnetic flocs enter the magnetic recovery system. The magnetic powder enters the magnetic recovery system and returns to the micro-magnetic flocculation reaction system. The sludge enters the sludge dewatering machine for dehydration to form a mud cake with a moisture content of no more than 60% for external transportation. After the relevant pollutants are removed from the influent, it is discharged into the river channel in compliance with the standards. The influent and effluent are equipped with online monitoring devices (COD, NH3-N, TN, TP);

[0101] During the above operation, the method of adding the front carbon source and the rear carbon source specifically includes:

[0102] (1) The influent TN concentration, influent COD concentration and instantaneous influent flow rate of the primary A pool are detected by online instrument periodic sampling, recorded as TN1 进水 、COD 进水 and Q1 进水 ;

[0103] (2) Calculate the concentration and amount of the pre-carbon source added to the primary A pool according to the following formula:

[0104] Pre-carbon source dosing concentration = K n *{[(TN1 进水 -TN2 出水 )*C / N-(COD 进水 *B / C)] / COD 当量};

[0105] In the above formula, the unit of the concentration of the pre-carbon source is mg / L, and the unit of the pre-carbon source dosage is m 3 / h; Kn is the set coefficient value; TN1 进水 The unit is mg / L; TN2 出水 is the total nitrogen concentration of the effluent set according to the effluent requirements of the first-level A pool, in mg / L; C / N is the ratio of organic carbon to effective fixed nitrogen in the set sewage, initially set to 5; COD 进水 The unit is mg / L; B / C is the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) in sewage; COD equivalent is the amount of oxygen required after all the carbon source per unit volume or unit mass is oxidized; Q1 进水 Unit: m 3 / h; Csolvent is the prepared concentration of the carbon source used;

[0106] In step (2), K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1,

[0107]

[0108] In the above formula, n is the number of times the online monitoring equipment takes samples;

[0109] In step (2), when the calculated pre-carbon source dosage is ≤0, the pre-carbon source is stopped; when the calculated pre-carbon source dosage is greater than 0 and less than the lower limit of the pre-carbon source dosing pump flow rate, the pre-carbon source dosing pump starts the intermittent dosing mode; when the calculated pre-carbon source dosage is greater than the upper limit of the pre-carbon source dosing pump flow rate, the pre-carbon source dosing pump keeps running at full frequency and triggers an alarm to reduce the water intake;

[0110] Among them, it also includes the reserved buffer time for adjusting the amount of pre-carbon source added;

[0111] Pre-carbon source reserved buffer time = t0 + V / Q1 进水 ;

[0112] In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 ;

[0113] (3) Collect the effluent TN concentration of the first-level A pool and the instantaneous inlet flow rate of the second-level A pool, recorded as TN3 出水 and Q2 进水 ;

[0114] (4) Calculate the amount of post-carbon source added to the secondary A pool according to the following formula:

[0115] Post-carbon source dosing concentration = K n *{[(TN3 出水 -TN4出水 )*C / N] / COD 当量};

[0116] Post-carbon source dosage = carbon source dosage concentration * Q2 进水 / C 溶药 ;

[0117] In the above formula, the unit of post-carbon source dosing concentration is mg / L, and the unit of post-carbon source dosing amount is m 3 / h; K n is the set coefficient value; TN3 出水 The unit is mg / L; TN4 出水 The total nitrogen concentration of the effluent set according to the effluent requirements of the secondary A pool, in mg / L, Q2 进水 Unit: m 3 / h;

[0118] In step (4), K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1,

[0119]

[0120] In the above formula, n is the number of times the online monitoring equipment takes samples.

[0121] In step (4), when the calculated amount of post-carbon source added is ≤0, the addition of post-carbon source is stopped; when the calculated amount of post-carbon source added is >0 and < the lower limit of the flow rate of the post-carbon source dosing pump, the post-carbon source dosing pump starts the intermittent dosing mode; when the calculated amount of post-carbon source added is > the upper limit of the flow rate of the post-carbon source dosing pump, the post-carbon source dosing pump keeps running at full frequency and triggers an alarm to reduce the water intake;

[0122] Among them, it also includes the reserved buffer time for adjusting the amount of post-carbon source addition;

[0123] Post-carbon source reserved buffer time = t0 + V / Q2 进水 ;

[0124] In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 .

[0125] In this embodiment, when adding carbon source in the sewage denitrification system, two carbon source dosing points are involved, namely, the front carbon source dosing point, located at the water inlet of the first-level A pool, and the rear carbon source dosing point, located at the water inlet of the second-level A pool; the type of sewage to be treated is mainly domestic sewage, and the designed water inlet is 5000m 3 / d, the designed influent water quality standard is COD≤250mg / L, BOD≤150mg / L, total nitrogen≤40mg / L, ammonia nitrogen≤35mg / L, total phosphorus≤4mg / L, SS≤300mg / L;

[0126] Comparative Example 2

[0127] This comparative example also proposes a method for adding a carbon source to a sewage denitrification system. The sewage denitrification system and the carbon source dosing point are the same as those in Example 2, except that the carbon source addition method is based on the experience of the on-site operators.

[0128] refer to Figure 5 It can be seen that the influent TN of Example 2 fluctuates between 12.36-35.24 mg / L, with an average of 26.77 mg / L, and the effluent TN fluctuates between 2-8.51 mg / L, with an average of 6.47 mg / L. The TN removal rate of Example 2 is 75.83%; the influent TN of Comparative Example 2 fluctuates between 13.65-37.36 mg / L, with an average of 26.75 mg / L, and the effluent TN fluctuates between 4.18-11.39 mg / L, with an average of 7.87 mg / L. The TN removal rate of Comparative Example 2 is 70.57%; by comparison, it can be seen that the dosing method of Example 2 has a better TN removal effect.

[0129] refer to Figure 6 It can be seen that the average carbon source consumption per kilogram of total nitrogen removed in Example 2 is 8.26Kg, and the average carbon source consumption in Comparative Example 2 is 13.22Kg. Example 2 saves 38% in the use of agents relative to Comparative Example 2, showing higher efficiency; and the average data variance of the carbon source consumption per kilogram of total nitrogen removed in Example 2 is 1.19, and the average data variance of the carbon source consumption per kilogram of total nitrogen removed in Comparative Example 2 is 60.62. By comparison, it can be seen that the dosing situation in Example 2 is relatively stable.

[0130] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for accurately adding a carbon source to a sewage denitrification system, characterized in that: The sewage denitrification system comprises at least one level of AO treatment system; each level of AO treatment system comprises an anaerobic tank and an aerobic tank connected in sequence; The precise carbon source addition method comprises: S1, collecting the influent TN concentration, influent COD concentration and instantaneous influent flow rate of the anaerobic tank; S2, based on the influent TN concentration, influent COD concentration and instantaneous influent flow collected in step S1, calculate the concentration and amount of the pre-carbon source added to the anaerobic tank; Among them, the calculation formulas for the concentration and amount of the pre-carbon source are: Pre-carbon source dosing concentration = K n *{[(TN1 进水 -TN2 出水 )*C / N-(COD 进水 *B / C)] / COD 当量 }; Pre-carbon source dosage = pre-carbon source dosage concentration * Q1 进水 / C 溶药 ; In the above formula, the unit of the concentration of the pre-carbon source is mg / L, and the unit of the pre-carbon source dosage is m 3 / h; K n is the set coefficient value; TN1 进水 TN2 is the total nitrogen concentration of the anaerobic tank influent, in mg / L; 出水 It is the total nitrogen concentration of the effluent set according to the effluent requirements of the AO treatment system, in mg / L; C / N is the ratio of organic carbon to effective fixed nitrogen in the set sewage; COD 进水 is the COD concentration of the anaerobic tank influent, in mg / L; B / C is the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) in the sewage; COD 当量 Q1 is the amount of oxygen required after all the carbon source per unit volume or unit mass is oxidized; 进水 is the instantaneous flow rate of anaerobic tank inlet, in m 3 / h; C 溶药 is the prepared concentration of the carbon source used.

2. The precise carbon source dosing method for a sewage denitrification system according to claim 1, characterized in that: The initial setting of C / N is 5.

3. The precise carbon source dosing method for a sewage denitrification system according to claim 1 or 2, characterized in that: In step S2, K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1, In the above formula, n is the number of times the online monitoring equipment takes samples.

4. The precise carbon source dosing method for a wastewater denitrification system according to any one of claims 1 to 3, characterized in that: In step S2, when the calculated pre-carbon source dosage is ≤0, the addition of the pre-carbon source is stopped; when the calculated pre-carbon source dosage is greater than 0 and less than the lower limit of the flow rate of the pre-carbon source dosing pump, the pre-carbon source dosing pump starts the intermittent dosing mode; when the calculated pre-carbon source dosage is greater than the upper limit of the flow rate of the pre-carbon source dosing pump, the pre-carbon source dosing pump maintains full frequency operation and triggers an alarm to reduce the water intake.

5. The method for accurately adding a carbon source based on a sewage treatment system according to any one of claims 1 to 4, characterized in that: Step S2 also includes adjusting the reserved buffer time of the pre-carbon source dosage; Pre-carbon source reserved buffer time = t0 + V / Q1 进水 ; In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 .

6. The precise carbon source dosing method for a sewage denitrification system according to any one of claims 1 to 5, characterized in that: The sewage denitrification system also includes a deep treatment system, which includes a denitrification deep bed filter or a deep treatment anaerobic tank; The carbon source precise dosing method also includes: S3, collecting the TN concentration of the effluent of the AO treatment system and the instantaneous water inflow of the denitrification deep bed filter or the deep treatment anaerobic tank; S4, based on the effluent TN concentration and instantaneous inlet flow rate collected in step S3, calculating the concentration and amount of post-carbon source added to the denitrification deep bed filter or the deep treatment anaerobic tank; Among them, the calculation formulas for the post-carbon source dosing concentration and the post-carbon source dosing amount are: Post-carbon source dosing concentration = K n *{[(TN3 出水 -TN4 出水 )*C / N] / COD 当量 }; Post-carbon source dosage = carbon source dosage concentration * Q2 进水 / C 溶药 ; In the above formula, the unit of post-carbon source dosing concentration is mg / L, and the unit of post-carbon source dosing amount is m 3 / h; K n is the set coefficient value; TN3 出水 TN4 is the total nitrogen concentration of the effluent from the AO treatment system, in mg / L; 出水 The total nitrogen concentration of the effluent is set according to the effluent requirements of the deep treatment system, in mg / L, Q2 进水 is the instantaneous flow rate of water in the denitrification deep bed filter or deep treatment anaerobic tank, in m 3 / h; Preferably, C / N is initially set to 5.

7. The precise carbon source dosing method for a wastewater denitrification system according to claim 6, characterized in that: In step S4, K n The initial setting is 1, that is, when n = 0, K n =1; when n≥1, In the above formula, n is the number of times the online monitoring equipment takes samples.

8. The precise carbon source dosing method for a sewage denitrification system according to claim 6 or 7, characterized in that: In step S4, when the calculated post-carbon source dosage is ≤0, stop adding the post-carbon source; when the calculated post-carbon source dosage is >0 and < the lower limit of the post-carbon source dosing pump flow rate, the post-carbon source dosing pump starts the intermittent dosing mode; when the calculated post-carbon source dosage is > the upper limit of the post-carbon source dosing pump flow rate, the post-carbon source dosing pump maintains full frequency operation and triggers an alarm to reduce the water intake.

9. The precise carbon source dosing method for a sewage denitrification system according to any one of claims 6 to 8, characterized in that: Step S2 also includes adjusting the reserved buffer time for the post-carbon source dosage; Post-carbon source reserved buffer time = t0 + V / Q2 进水 ; In the above formula, t0 is the time required for the online monitoring equipment to detect the TN concentration of the influent, in h; V is the total effective volume of the process structure between the online monitoring sampling point and the carbon source dosing point, in m 3 .

10. A precise carbon source dosing system for a sewage denitrification system, characterized in that: The system adopts the precise carbon source addition method according to any one of claims 1-9.

Images