Whole-flow intelligent precise control system of sewage treatment plant

Abstract

The invention relates to the field of sewage treatment, and provides a sewage treatment plant whole-flow intelligent accurate control system which comprises a waterline control subsystem, a mud line control subsystem and an accurate dosing subsystem. By accurately controlling the water level, the mud level and various dosing processes in the sewage treatment process, the automation level and the control level of the sewage treatment process are improved, and meanwhile, the control capability and the control precision of the dosing process are enhanced by integrally controlling the water level and the mud level.

Description

Technical Field

[0001] This application belongs to the field of wastewater treatment technology, specifically involving an intelligent and precise control system for the entire process of a wastewater treatment plant. Background Technology

[0002] Full-process control of wastewater treatment is the development trend of wastewater treatment. However, due to the nonlinear, multivariable, and time-varying characteristics of wastewater treatment processes, it is difficult to measure operating parameters and formulate control decisions in automatic control systems. Currently, most practically applied systems remain at the level of single-parameter control, such as wastewater treatment aeration, chemical phosphorus removal, and precise carbon source dosing. They lack holistic waterline control and sludge discharge control, which affects both the overall automation and control level of wastewater treatment and the control accuracy of the aforementioned single-parameter systems. Summary of the Invention

[0003] This application provides an intelligent and precise control system for the entire process of a wastewater treatment plant to solve or partially solve the problems mentioned in the background art.

[0004] This application provides an intelligent and precise control system for the entire process of a wastewater treatment plant, including a water line control subsystem, a sludge line control subsystem, and a precision dosing subsystem; The water line control subsystem controls the water level of the water line that sequentially enters the inlet pump room, bar screen, primary sedimentation tank, biological treatment tank, secondary sedimentation tank, high sedimentation tank, and V filter. The mud level control subsystem controls the mud level in the primary sedimentation tank, secondary sedimentation tank, and precipitate sedimentation tank. The precision dosing subsystem performs dosing on the biochemical tank. Chemical dosing was performed: phosphorus removal and phosphorus ammonium phosphate (PAM) were added to the sedimentation tank, and sodium chloride (NaClO) was added to the contact disinfection tank.

[0005] Preferably, the specific method for the waterline control subsystem to maintain a constant liquid level in the waterline includes: S1: Inlet pump room. The inlet pump room is subject to joint control of liquid level and flow rate. During normal operation, the liquid level is maintained in the preset range L1. When the liquid level exceeds the preset range L1, the inlet flow rate Q = Q + Q_limit1 is set. When the inlet flow rate reaches the second threshold Q2, Q = Q + Q_limit1 + Q_limit2 is set, Q2 > Q1, Q_limit1 > Q_limit2. S2: Bar screen tank, when the influent flow rate reaches the second threshold Q2, the bar screen is activated to bypass; S3: Primary sedimentation tank. When the influent flow rate reaches the second threshold Q2, the primary sedimentation tank overrun is activated. S4: Biochemical tank. The external reflux returns at a preset ratio Ratef1(Q)*Q1_re, where Ratef1(Q) is the reflux ratio curve, Q is the influent flow rate, and Q1_re is the maximum external reflux flow rate. When Q ≥ the third threshold Q3, let Ratef1(Q) = 1, Q3 < Q1; Adjust the influent volume of each stage synchronously according to the change of the influent flow rate at a preset ratio Rate1; S5: Secondary sedimentation tank. When the water layer height H ≥ the preset height H1, perform constant liquid level control on the influent water level to maintain its liquid level line within the preset interval L1; When H < H1, control the liquid level line ≤ less than the preset value L2; S6: High sedimentation tank. Perform constant liquid level control on the influent water level; The high sedimentation reflux returns at a preset ratio Ratef2(Q)*Q2_re, where Ratef2(Q) is the reflux ratio curve, Q is the influent flow rate, and Q2_re is the maximum high sedimentation reflux flow rate. When the influent water volume is greater than the second threshold Q2, let Ratef2(Q) = 1; S7: V filter. Perform constant liquid level control on the influent water level.

[0006] Preferably, the preset interval L1 is 4.5 to 5.5 m, the first threshold Q1 is 11000 m³ / h, the second threshold Q2 is 12500 m³ / h, Q_limit1 is 500 m³ / h, Q_limit2 is 200 m³ / h, the third threshold Q3 is 10000 m³ / h, the preset ratio Rate1 is 2:4:3:1, the preset height H1 is 1 m, and the preset value L2 is 8 m.

[0007] Preferably, the specific method for the sludge line control subsystem to control the sludge level is as follows: S10: Primary sedimentation tank. Control the sludge layer not to be higher than the preset height Hsl-1; S20: Secondary sedimentation tank. Adjust the remaining amount of the sludge layer according to MLSS to ensure that the water layer is not lower than the preset value H3; S30: High sedimentation tank. Ensure that the sludge layer is not higher than the second root and not less than the first root; S40: When discharging sludge from the primary sedimentation tank or the high sedimentation tank, synchronously discharge the secondary sedimentation tank.

[0008] Preferably, the preset height Hsl-1 is 1.5 m, the preset value H3 is 2 m, the height represented by the first root is 0.8 m, and the height represented by the second root is 1.6 m.

[0009] Preferably, in the step S30, the formula for the secondary sedimentation tank to adjust the remaining amount of the sludge layer according to MLSS is as follows: Wherein, MLSS0 is the MLSS detection value, MLSSre is the preset MLSS target value, V is the volume of the secondary sedimentation tank, Tur is the sludge turbidity, α is the settling ratio coefficient, and β is the sludge age coefficient.

[0010] Preferably, the formula for setting the settlement ratio coefficient α is as follows: in, The actual / target sludge settling ratio is given, and k1 is the SV30 sensitivity coefficient. The formula for setting the mud age coefficient β is as follows: in, Actual / target sludge age, k2 is the SRT sensitivity coefficient.

[0011] Preferably, the specific method for controlling precise dosing by the precision dosing subsystem is as follows: S11: Use the following formula to process the biological tank. Administering medication, , in, for The actual concentration, for concentration, for The target concentration is given by Q, where Q is the influent flow rate and q is the theoretical dosage of carbon source per unit volume of water. S12: Set the dosage of P removal agent based on the influent P concentration, the target effluent P concentration, and the influent flow rate Q; S13: Determine the dosage of PAM and NaClO based on the influent flow rate Q.

[0012] Compared with the prior art, the beneficial effects of this application are as follows: This application uses a water line control subsystem, a sludge line control subsystem, and a precision dosing subsystem to precisely control the water level, sludge level, and various dosing processes in the wastewater treatment process, thereby improving the automation and control levels of the wastewater treatment process. At the same time, the overall control of the water level and sludge level also enhances the control capability and accuracy of the dosing process. Attached Figure Description

[0013] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1 This is a schematic diagram of the system composition of this application. Figure 2 This is a schematic diagram of the method flow of this application. Figure 3This is a flowchart of the wastewater treatment process. Detailed Implementation

[0015] The specification and claims use certain terms to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0016] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0017] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0018] Example 1 like Figures 1 to 3 As shown, this application provides an intelligent and precise control system for the entire process of a wastewater treatment plant, characterized by including a water line control subsystem, a sludge line control subsystem, and a precise chemical dosing subsystem; The water line control subsystem controls the water level of the water line that sequentially enters the inlet pump room, bar screen, primary sedimentation tank, biological treatment tank, secondary sedimentation tank, high sedimentation tank, and V filter. The mud level control subsystem controls the mud level in the primary sedimentation tank, secondary sedimentation tank, and precipitate sedimentation tank. The precision dosing subsystem performs dosing on the biochemical tank. Chemical dosing was performed: phosphorus removal and phosphorus ammonium phosphate (PAM) were added to the sedimentation tank, and sodium chloride (NaClO) was added to the contact disinfection tank.

[0019] The hardware structure applied in this application includes a central control component, a data acquisition component, detection instruments, an output component, and an execution component. Specifically, the central control component is the main control computer, the data acquisition component and the output component are PLC controllers. The detection instruments include detection devices such as sludge level meters, nitrate nitrogen detectors, and orthophosphoric acid detectors. The execution components include execution devices such as inlet pumps, surplus pumps (sludge discharge), and chemical dosing pumps. This application is deployed and set on the main control computer.

[0020] Preferably, the specific method for the water line control subsystem to perform constant liquid level control on the water line includes: S1: In the inlet pump house, perform combined liquid level and flow control on the inlet pump house. During normal operation, the liquid level is maintained within the preset interval L1. When the liquid level exceeds the preset interval L1, let the inlet flow rate Q = Q + Q_limit1. When the inlet flow rate reaches the second threshold Q2, let Q = Q + Q_limit1 + Q_limit2, where Q2 > Q1 and Q_limit1 > Q_limit2. S2: In the grit chamber, when the inlet flow rate reaches the second threshold Q2, open the grit bypass. S3: In the primary sedimentation tank, when the inlet flow rate reaches the second threshold Q2, open the primary sedimentation tank bypass. S4: In the biochemical tank, the external reflux is carried out at the preset proportion Ratef1(Q)*Q1_re, where Ratef1(Q) is the reflux proportion curve, Q is the inlet flow rate, and Q1_re is the maximum external reflux flow rate. When Q ≥ the third threshold Q3, let Ratef1(Q) = 1, where Q3 < Q1. Adjust the water inflow of each stage synchronously according to the preset proportion Rate1 according to the change of the inlet flow rate; S5: In the secondary sedimentation tank, when the water layer height H ≥ the preset height H1, perform constant liquid level control on the inlet water level to maintain its liquid level line within the preset interval L1; When H < H1, control the liquid level line ≤ less than the preset value L2; S6: In the high sedimentation tank, perform constant liquid level control on the inlet water level; The high sedimentation reflux is carried out at the preset proportion Ratef2(Q)*Q2_re, where Ratef2(Q) is the reflux proportion curve, Q is the inlet flow rate, and Q2_re is the maximum high sedimentation reflux flow rate. When the inlet water volume is greater than the second threshold Q2, let Ratef2(Q) = 1; S7: In the V-filter, perform constant liquid level control on the inlet water level.

[0021] This application uses constant liquid level correlation control for each treatment tank, which helps to avoid problems such as water flow impact and unstable hydraulic retention time (HRT) caused by liquid level fluctuations. A stable liquid level in the biochemical treatment unit can ensure that the microbial community is in a constant living environment, maintain the biodegradation efficiency of activated sludge, and ensure that the water flow is evenly distributed in the treatment unit, reducing phenomena such as short-circuiting and dead zones.

[0022] In step S1, the liquid level refers to the liquid level in the inlet pump room, and the inlet flow rate refers to the flow rate of water transported from the inlet pump room to the bar screen.

[0023] In steps S2 and S3, "overtaking" refers to the operation of bypassing the current processing step and allowing the water to flow to the next processing unit. Taking a bar screen tank as an example, before the influent flow rate reaches the second threshold Q2, all the influent must pass through the bar screen (coarse bar screen, fine bar screen) to flow to the next primary sedimentation tank. However, after the bar screen is bypassed, some of the influent will enter the next primary sedimentation tank without being filtered by the bar screen.

[0024] In step S4, external reflux refers to the reflux from the end of the secondary sedimentation tank back to the beginning of the biological treatment tank. Ratef1(Q) is an external reflux ratio curve summarized based on actual sewage treatment experience, with a value of [0,1]. When the influent reaches the third threshold Q3, Ratef1(Q) takes the maximum value of 1. The biological treatment tank in this application is a multi-stage series biological treatment tank. When the influent flow rate changes, the influent flow rate of each stage of the biological treatment tank changes, and the sum of their changes is equal to the total change in influent flow rate. The preset ratio Rate1 is the preset relative ratio adjusted by each stage of the biological treatment tank.

[0025] In step S6, high sedimentation reflux refers to the reflux from the end of the high sedimentation tank back to the beginning. Ratef2(Q) is a high sedimentation reflux ratio curve summarized based on actual sewage treatment experience, with a value of [0,1]. When the influent reaches the third threshold Q2, Ratef1(Q) takes the maximum value of 1.

[0026] Specifically, the preset interval L1 is 4.5 to 5.5 m, the first threshold Q1 is 11000 m³ / h, the second threshold Q2 is 12500 m³ / h, Q_limit1 is 500 m³ / h, Q_limit2 is 200 m³ / h, the third threshold Q3 is 10000 m³ / h, the preset ratio Rate1 is 2:4:3:1 (four-stage biological tank), the preset height H1 is 1 m, and the preset value L2 is 8 m.

[0027] Specifically, the mudline control subsystem controls the mud level using the following method: S10: Primary sedimentation tank, controlling the mud layer to not exceed the preset height Hsl_1; S20: Secondary sedimentation tank. Adjust the remaining amount of mud layer according to MLSS to ensure that the water layer is not lower than the preset value H3. S30: High sedimentation tank, ensuring a mud layer height greater than or equal to 0.8 meters and less than or equal to 1.6 meters; S40: When discharging sludge from the primary sedimentation tank or the secondary sedimentation tank, sludge should be discharged simultaneously from the secondary sedimentation tank.

[0028] Specifically, in step S10, the preset height Hsl_1 is 1.5m, and in step S20, the preset value H3 is 2m.

[0029] Preferably, in step S20, the formula for adjusting the remaining amount of sludge in the secondary sedimentation tank according to MLSS is as follows: Wherein, MLSS0 is the MLSS detection value, MLSSre is the preset MLSS target value, V is the volume of the secondary sedimentation tank, Tur is the sludge turbidity, α is the settling ratio coefficient, and β is the sludge age coefficient.

[0030] MLSS (Mixed Liquor Suspended Solids) refers to the suspended solids content (unit: mg / L or g / L) of the activated sludge mixed liquor in the aeration tank. It is a key indicator for measuring the biomass in the activated sludge process, reflecting the concentration of activated sludge in the aeration tank, and directly affecting the biochemical treatment efficiency and the sludge-water separation effect in the secondary sedimentation tank.

[0031] α is used to reflect the effect of sludge settling ratio (SV30) on sludge layer height. If SV30 remains high, even if MLSS is within the normal range, it may indicate sludge bulking, requiring increased sludge discharge to reduce sludge layer height. β is used to reflect the effect of sludge age (SRT) on sludge layer height. Excessive SRT can lead to sludge aging and artificially high MLSS. In this case, sludge discharge is needed to shorten SRT and optimize sludge layer structure.

[0032] Furthermore, the formula for setting α is as follows: in, The actual / target sludge settling ratio is given, and k1 is the SV30 sensitivity coefficient (empirical value, recommended 0.5~1.0, take a larger value when the risk of sludge bulking is high). The formula for setting β is as follows: in, Actual / target sludge age, k2 is the SRT sensitivity coefficient (empirical value, recommended 0.3~0.6, take a larger value when the risk of sludge aging is high).

[0033] Preferably, the specific method for controlling precise dosing by the precision dosing subsystem is as follows: S11: Use the following formula to process the biological tank. Administering medication, , in, for The actual concentration, for concentration, for The target concentration is given by Q, where Q is the influent flow rate and q is the theoretical dosage of carbon source per unit volume of water. S12: Set the dosage of P removal agent based on the influent P concentration, the target effluent P concentration, and the influent flow rate Q; S13: Determine the dosage of PAM and NaClO based on the influent flow rate Q.

[0034] In step S12, except that the dosage of P is equal to the unit dosage * Q * (influent P concentration - effluent target P concentration), the unit dosage is the amount of chemical required to reduce the P concentration by one unit per unit volume of water.

[0035] In step S13, PAM (polyacrylamide, flocculant) plays a role in sedimentation tank coagulation aid and enhanced sludge-water separation in high sedimentation tank. PAM dosage = Q*k, where k is the PAM dosage per unit volume of water, which is an empirical value. Preferably, its value ranges from 1 to 3 mg / L.

[0036] In step S13, the specific method for adding NaClO to the contact disinfection tank is as follows: First, calculate the total chlorine requirement per unit volume of water. Total chlorine requirement = consumption + target residual chlorine. Consumption refers to the amount of chlorine consumed by organic matter (COD) and ammonia nitrogen in the water. Target residual chlorine refers to the chlorine content of the water flowing out of the contact disinfection tank, which is a preset value. NaClO dosage = total chlorine requirement * Q, where Q is the influent flow rate.

[0037] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A fully intelligent and precise control system for wastewater treatment plants, characterized in that: It includes a water line control subsystem, a mud line control subsystem, and a precise chemical dosing subsystem; The water line control subsystem performs constant liquid level control on the water line that sequentially enters the intake pump house, grille chamber, primary sedimentation tank, biochemical tank, secondary sedimentation tank, high sedimentation tank, and V-filter; The mud line control subsystem controls the mud levels in the primary sedimentation tank, secondary sedimentation tank, and high sedimentation tank; The precision dosing subsystem performs dosing on the biochemical tank. Chemical dosing was performed: phosphorus removal and phosphorus ammonium phosphate (PAM) were added to the sedimentation tank, and sodium chloride (NaClO) was added to the contact disinfection tank.

2. The intelligent precise control system for the entire process of a sewage treatment plant according to claim 1, wherein: The specific method for the water line control subsystem to perform constant liquid level control on the water line includes: S1: Intake pump house, perform combined liquid level and flow control on the intake pump house. During normal operation, the liquid level is maintained within the preset range L1. When the liquid level exceeds the preset range L1, set the influent flow rate Q = Q + Q_limit1. When the influent flow rate reaches the second threshold Q2, set Q = Q + Q_limit1 + Q_limit2, where Q2 > Q1 and Q_limit1 > Q_limit2; S2: Grille chamber, when the influent flow rate reaches the second threshold Q2, open the grille bypass; S3: Primary sedimentation tank, when the influent flow rate reaches the second threshold Q2, open the primary sedimentation tank bypass; S4: Biochemical tank, the external reflux is returned at the preset ratio Ratef1(Q) * Q1_re, where Ratef1(Q) is the reflux ratio curve, Q is the influent flow rate, and Q1_re is the maximum external reflux flow rate. When Q ≥ the third threshold Q3, set Ratef1(Q) = 1, where Q3 < Q1; Adjust the influent volume of each stage synchronously according to the preset ratio Rate1 according to the change in the influent flow rate; S5: Secondary sedimentation tank, when the water layer height H ≥ the preset height H1, perform constant liquid level control on the influent water level to maintain its liquid level line within the preset range L1; When H < H1, control the liquid level line ≤ less than the preset value L2; S6: High sedimentation tank, perform constant liquid level control on the influent water level; The high sedimentation reflux is returned at the preset ratio Ratef2(Q) * Q2_re, where Ratef2(Q) is the reflux ratio curve, Q is the influent flow rate, and Q2_re is the maximum high sedimentation reflux flow rate. When the influent water volume is greater than the second threshold Q2, set Ratef2(Q) = 1; S7: V-filter, perform constant liquid level control on the influent water level.

3. The intelligent precise control system for the entire process of a sewage treatment plant according to claim 2, wherein: The preset range L1 is 4.5 to 5.5 m, the first threshold Q1 is 11000 m³ / h, the second threshold Q2 is 12500 m³ / h, Q_limit1 is 500 m³ / h, Q_limit2 is 200 m³ / h, the third threshold Q3 is 10000 m³ / h, the preset ratio Rate1 is 2:4:3:1, the preset height H1 is 1 m, and the preset value L2 is 8 m.

4. The intelligent precise control system for the entire process of a sewage treatment plant according to claim 1, wherein: The specific method for the mud line control subsystem to control the mud level is as follows: S10: Primary sedimentation tank, control the mud layer not to be higher than the preset height Hsl-1; S20: Secondary sedimentation tank, adjust the remaining amount of the mud layer according to MLSS to ensure that the water layer is not lower than the preset value H3; S30: High sedimentation tank, ensuring that the mud layer is not higher than the second shaft and not lower than the first shaft; S40: When discharging sludge from the primary sedimentation tank or the secondary sedimentation tank, the sludge should be discharged simultaneously from the secondary sedimentation tank.

5. The intelligent and precise control system for the entire process of a wastewater treatment plant according to claim 4, characterized in that: The preset height Hsl-1 is 1.5m, the preset value H3 is 2m, the height represented by the first root is 0.8m, and the height represented by the second root is 1.6m.

6. The intelligent and precise control system for the entire process of a wastewater treatment plant according to claim 4, characterized in that: In step S30, the formula for adjusting the remaining amount of sludge in the secondary sedimentation tank according to MLSS is as follows: Wherein, MLSS0 is the MLSS detection value, MLSSre is the preset MLSS target value, V is the volume of the secondary sedimentation tank, Tur is the sludge turbidity, α is the settling ratio coefficient, and β is the sludge age coefficient.

7. The intelligent and precise control system for the entire process of a wastewater treatment plant according to claim 6, characterized in that: The formula for setting the settlement ratio coefficient α is as follows: in, The actual / target sludge settling ratio is given, and k1 is the SV30 sensitivity coefficient. The formula for setting the mud age coefficient β is as follows: in, Actual / target sludge age, k2 is the SRT sensitivity coefficient.

8. The intelligent and precise control system for the entire process of a wastewater treatment plant according to claim 1, characterized in that: The specific method for controlling precise dosing by the precision dosing subsystem is as follows: S11: Use the following formula to process the biological tank. Administering medication, ， in, for The actual concentration, for concentration, for The target concentration is given by Q, where Q is the influent flow rate and q is the theoretical dosage of carbon source per unit volume of water. S12: Set the dosage of P removal agent based on the influent P concentration, the target effluent P concentration, and the influent flow rate Q; S13: Determine the dosage of PAM and NaClO based on the influent flow rate Q.

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