An operation control system and method for a split aeration self-circulating sludge expansion bed
Through the combination of PLC controller and online monitoring equipment, the aeration volume and sewage return volume are automatically adjusted, which solves the stable operation problem of the separate aeration self-circulating sludge expansion bed reactor, and realizes automatic control and efficient sewage treatment.
Patent Information
- Application Number
- CN202311382573.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-24
- Publication Date
- 2025-08-15
- Estimated Expiration
- 2043-10-24
AI Technical Summary
The separated aerated self-circulating sludge expansion bed reactor needs to be maintained strictly in operating conditions. The existing manual adjustment is prone to deviations and requires a large amount of manual monitoring to ensure stable operation, resulting in high cost and low efficiency.
The PLC controller is used to combine online monitoring equipment and electric adjustment equipment to detect parameters such as COD, ammonia nitrogen, dissolved oxygen and sludge concentration in the reactor in real time, and adjust the aeration volume and sewage return volume through the gas solenoid valve and the liquid return valve to achieve automatic control.
The stable operation of the separated aerated self-circulating sludge expansion bed is achieved, reducing manual intervention, reducing energy consumption, improving processing efficiency, and ensuring that the reactor always operates in the best state.
Smart Images
Figure CN117125814B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an operation control system and method for sewage treatment, and more particularly to an operation control system and method for a split aeration self-circulating sludge expansion bed. Background Art
[0002] The granular sludge process has a higher organic load than the traditional activated sludge process, is rich in biomass, is more space-efficient, and has higher treatment efficiency. However, the activated sludge process still dominates wastewater treatment, primarily due to its inherent limitations, which have hampered its promotion and development.
[0003] Granular sludge operates under relatively demanding conditions, potentially causing disintegration or collapse if not carefully managed. This is particularly true for split-aeration, self-circulating expanded sludge bed reactors, which utilize independent aeration columns to generate a pressure differential to drive the reactor's self-circulation. Maintaining a relatively stable upward flow of water, thereby providing the rising shear force, is crucial. Such systems can significantly alter the sludge bed height and operating conditions within the reactor columns with changes in aeration and reflux valve openings, necessitating continuous monitoring and maintenance by specialized personnel to ensure proper operation.
[0004] To maintain the stable operation of the split-aeration, self-circulating sludge expansion bed, achieve autonomous regulation, and reduce labor and accident costs, automated control technology will become an indispensable component. Furthermore, manual adjustments often result in over-adjustment or misaligned adjustments. By utilizing front-end online monitoring equipment and logic control methods, along with back-end electric adjustment equipment, intelligent, stable regulation of the split-aeration, self-circulating sludge expansion bed reactor can be achieved. Machine regulation is more rigorous and logical, and allows for continuous correction to reduce adjustment deviations, features that manual adjustments lack. Summary of the Invention
[0005] In order to overcome the disadvantages of the above technical problems, the present invention provides an operation control system and method for a split aeration self-circulating sludge expansion bed.
[0006] The operation control system of the split aeration self-circulating sludge expansion bed of the present invention is composed of a reactor and an operation control system. The reactor is composed of a reaction column, an aeration column, a blower, an upper circulation pipe and a lower circulation pipe. The upper end of the aeration column is connected to the lower end of the reaction column through the upper circulation pipe, and the upper end of the reaction column is connected to the lower end of the aeration column through the lower circulation pipe. The middle and lower parts of the upper circulation pipe are connected to the water inlet pipe, and the upper part of the reaction column is connected to the water outlet pipe. Granular sludge for treating sewage is inoculated in the reaction column, an aeration disk is provided at the bottom of the aeration column, and the blower is connected to the aeration disk via an aeration pipeline. Under the aeration action of the aeration disk, the sewage density at the bottom of the aeration column is reduced and the water on the liquid surface is increased. The system is characterized in that the operation control system comprises a PLC controller, online COD, online ammonia nitrogen, online No. 1 DO, online No. 1 SS, online No. 2 SS, online pH, online No. 2 DO, a liquid reflux valve, and a gas solenoid valve; the detection terminals of online COD, online ammonia nitrogen, online No. 1 DO, and online No. 1 SS are all placed at the top of the reaction column, and the signal output terminals are all connected to the input terminals of the PLC controller;
[0007] The detection ends of the online pH and online No. 2 DO are both placed at the top of the aeration column, and the signal output ends are connected to the input end of the PLC controller; the detection end of the online No. 2 SS is set at the upper end of the lower circulation pipe, and the signal output end is connected to the input end of the PLC controller; the gas solenoid valve is set on the aeration pipeline between the blower and the aeration disk, and the liquid reflux valve is set on the upper circulation pipe between the water inlet pipe and the reaction column. The control ends of the gas solenoid valve and the liquid reflux valve are both connected to the output end of the PLC controller;
[0008] The PLC controller detects the COD, ammonia nitrogen, dissolved oxygen and sludge concentration of the sewage at the top of the reaction column through online COD, online ammonia nitrogen, online No. 1 DO and online No. 1 SS respectively, detects the pH and dissolved oxygen concentration of the sewage at the top of the aeration column through online pH and online No. 2 DO respectively, and detects the sludge concentration of the effluent from the reaction column through online No. 2 SS. According to the detected values, the aeration volume and sewage reflux volume are controlled and adjusted through the gas solenoid valve and the liquid reflux valve respectively to control the reactor to automatically and normally perform sewage treatment.
[0009] The operation control system of the split aeration self-circulating sludge expansion bed of the present invention includes a gas flow meter and a liquid flow meter. The liquid flow meter is arranged on the upper circulation pipe between the water inlet pipe and the aeration column, and the gas flow meter is arranged on the aeration pipeline between the blower and the aeration disk. The signal output ends of the gas flow meter and the liquid flow meter are both connected to the input end of the PLC controller.
[0010] In the operation control system of the split aeration self-circulating sludge expansion bed of the present invention, the liquid reflux valve is an electric liquid butterfly valve, and the gas solenoid valve is an electric gas ball valve.
[0011] In the operation control system of the split aeration self-circulating sludge expansion bed of the present invention, the PLC controller is connected to a monitoring PC via a communication optical fiber.
[0012] The sewage treatment control method of the operation control system of the split aeration self-circulating sludge expansion bed of the present invention is characterized by being achieved through the following steps:
[0013] a) Equipment operation: Start the operation control system, introduce the sewage to be treated through the water inlet pipe, turn on the blower, and the PLC controller opens the gas solenoid valve and liquid reflux valve. The blower aerates the sewage at the bottom of the aeration column through the aeration disk. Under the action of aeration, the sewage circulates between the aeration column and the reaction column. As the sewage enters the bottom of the reaction column, it causes the granular sludge to expand, causing the sludge bed in the reaction column to rise. The granular sludge in the sludge bed treats the sewage.
[0014] b) Parameter collection: The PLC controller collects COD, ammonia nitrogen, dissolved oxygen, and sludge concentrations of the sewage at the top of the reaction column, as well as the pH and dissolved oxygen concentration of the sewage at the top of the aeration column, in real time. Based on the collected data, the controller controls the opening of the gas solenoid valve and liquid reflux valve to ensure that the COD, ammonia nitrogen, dissolved oxygen, and sludge concentrations of the sewage at the top of the reaction column, as well as the pH and dissolved oxygen concentrations of the sewage at the top of the aeration column, are within the set ranges, thereby achieving automatic control operation of the sewage treatment system.
[0015] c) Oxygen supply and demand detection and control: The PLC controller collects the dissolved oxygen (DO1) of the sewage at the top of the reaction column through the online No. 1 DO meter. When the dissolved oxygen (DO1) is detected to be lower than 0.5 mg / L, indicating that the dissolved oxygen concentration of the sewage at the top of the reaction column is too low, the opening of the gas solenoid valve and the liquid reflux valve is increased to expand the aeration volume and increase the sewage return flow;
[0016] Collect the dissolved oxygen DO2 of the sewage at the top of the aeration column through the online No. 2 DO meter and determine whether the dissolved oxygen DO2 value is within the range of [4mg / L~7mg / L]. If the dissolved oxygen DO2 is lower than 4mg / L, it indicates that the aeration is too low, and the opening of the gas solenoid valve is increased to increase the aeration volume; if the dissolved oxygen DO2 is higher than 7mg / L, it indicates that there is excessive aeration in the aeration column, and the opening of the gas solenoid valve is reduced to appropriately reduce the aeration;
[0017] d) Pollutant concentration detection and control: The chemical oxygen demand (COD) of the wastewater at the top of the reaction column is detected online. If the COD is greater than 30 mg / L and the other parameters are normal, it indicates that the pollutant concentration in the wastewater at the top of the reaction column is too high. In this case, the opening of the liquid reflux valve is increased to increase the circulation volume and speed up the reaction.
[0018] e) Sludge deposition detection and control; If a large amount of sludge accumulates at the bottom, the biochemical reaction process will be hindered, and the dissolved oxygen consumption will drop sharply; when the sludge concentration in the sewage at the top of the reaction column detected by the online No. 1 SS is lower than 1000 mg / L, the dissolved oxygen DO2 of the sewage at the top of the aeration column detected by the online No. 2 DO is greater than 0.5 mg / L, the chemical oxygen demand COD of the sewage at the top of the reaction column detected by the online COD is greater than 30 mg / L, and the ammonia nitrogen concentration of the sewage at the top of the reaction column detected by the online ammonia nitrogen is greater than 5 mg / L, it is determined that the granular sludge in the reaction column has deposited, and the opening of the gas solenoid valve and the liquid reflux valve are increased at the same time, the aeration volume is expanded, the pressure difference between the two columns is increased, the reflux is promoted, the rising flow rate of the sewage in the reaction column is increased, and the height of the sludge layer is increased; through negative feedback regulation, the sludge layer in the reaction column can be stabilized at the preset height, and the rising flow rate of the sewage in the reaction column is also maintained within a certain range;
[0019] e) Detection and control of excessive sludge: When the sludge concentration in the reaction column effluent detected by the online No. 2 SS is greater than 1000 mg / L and lasts for more than 30 minutes, it indicates that the sludge layer in the reaction column is too high. This is not conducive to the biochemical reaction of the granular sludge on pollutants in the reaction column and will also cause sludge to enter the aeration column through the lower circulation pipe. In this case, the opening of the liquid reflux valve is reduced to reduce the rising flow rate of the sewage in the reaction column to reduce the height of the sludge layer in the reaction column;
[0020] f). Detection and control of a sharp increase in influent concentration: When the online No. 1 DO detects that the dissolved oxygen (DO1) in the sewage at the top of the reaction column drops sharply within a short period of time, such as DO1 becoming 0 within 5 minutes, and the ammonia nitrogen concentration in the sewage at the top of the reaction column rises to greater than 5 mg / L, and the online chemical oxygen demand (COD) rises to greater than 30 mg / L, indicating a sharp increase in the pollutant concentration in the influent, the opening of the liquid reflux valve and the gas solenoid valve are controlled to increase in a step-by-step manner to increase the aeration volume and sewage reflux rate, thereby enhancing the reaction column's ability to treat pollutants;
[0021] g). Detection and control of a sharp drop in influent concentration; When the pollutant concentration in the influent drops sharply, the oxygen demand in the reaction column decreases accordingly, and the oxygen supply is sufficient, and the online dissolved oxygen in the upper part of the reaction column rises rapidly. When the dissolved oxygen DO1 of the sewage at the top of the reaction column increases to 2×0.5 mg / L within 5 minutes, and at the same time, the chemical oxygen demand (COD) of the sewage at the top of the reaction column decreases to (30 mg / L) / 2 and the ammonia nitrogen concentration decreases to (5 mg / L) / 2 within 5 minutes, it indicates that the pollutant concentration in the influent has dropped sharply. To save aeration and reduce energy consumption, the aeration volume is appropriately reduced by reducing the opening of the gas solenoid valve;
[0022] h). Detection and control of abnormal water inlet; determine whether the pH of the sewage at the top of the aeration column detected by the online pH is within the range of [6.5,8]. If the pH is lower than 6.5 or higher than 8, it indicates that pollutants that will destroy the activity of granular sludge are present in the incoming sewage. At this time, first reduce the water inlet volume, then increase the opening of the gas solenoid valve and liquid reflux valve, increase aeration and increase liquid reflux, improve the reflux ratio, flush the sludge, and restore the sludge state to self-regulation.
[0023] The beneficial effects of the present invention are as follows: the operation control system and method of the split aeration self-circulating sludge expansion bed of the present invention, the reaction column and the aeration column are connected through the upper circulation pipe and the lower circulation pipe, and under the aeration effect of the blower on the aeration column through the aeration plate, the density of the sewage at the bottom of the aeration column is reduced, the liquid level in the aeration column rises, the sewage at the top of the aeration column flows into the bottom of the reaction column through the upper circulation pipe, part of the sewage at the top of the reaction column overflows and is discharged through the outlet, and part flows into the bottom of the aeration column through the lower circulation pipe, thus realizing self-circulating flow without the aid of external force during the sewage treatment process; the PLC controller in the operation control system is connected to the online COD, online ammonia nitrogen, online No. 1 DO and online No. 1 DO through the online COD, online ammonia nitrogen, online No. 1 DO and online No. 1 DO. SS collects the chemical oxygen demand (COD), ammonia nitrogen concentration, dissolved oxygen concentration and sludge concentration of the sewage at the top of the reaction column in real time, collects the pH and dissolved oxygen solubility of the sewage at the top of the aeration column through online pH and online No. 2 DO, and collects the sludge concentration in the effluent of the reaction column through online No. 2 SS. Based on the collected parameter data, the gas solenoid valve and the liquid reflux valve are controlled to the appropriate opening to control the stable operation of the reactor for sewage treatment. It can also realize the detection of oxygen supply and demand status, pollutant concentration, sludge deposition, excessive sludge bed height, sharp increase in influent concentration, sharp decrease in influent concentration, and abnormal influent status, and give the most reasonable control feedback to keep the reactor in the best operating state at all times. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a schematic diagram of the operation control system of the split aeration self-circulating sludge expansion bed of the present invention.
[0025] In the figure: 1 is online COD, 2 is online ammonia nitrogen, 3 is online No. 1 DO, 4 is online No. 1 SS, 5 is liquid flow meter, 6 is online pH, 7 is online No. 2 DO, 8 is gas flow meter, 9 is PLC controller, 10 is monitoring PC, 11 is liquid reflux valve, 12 is gas solenoid valve, 13 is blower, 14 is reaction column, 15 is aeration column, 16 is upper circulation pipe, 17 is lower circulation pipe, 18 is water inlet pipe, 19 is water outlet pipe, 20 is aeration plate, and 21 is online No. 2 SS. Implementation Method
[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0027] like Figure 1 As shown, a schematic diagram of the operation control system of the split aeration self-circulating sludge expansion bed of the present invention is provided. The reactor is composed of two parts: a reactor and an operation control system. The reactor is composed of a reaction column 14, an aeration column 15, an upper circulation pipe 16, a lower circulation pipe 17, an inlet pipe, an outlet pipe 19, a blower 13, and an aeration plate 20. The reaction column 14 and the aeration column 15 are both upright columns with cylindrical cavities inside. The top of the aeration column 15 is connected to the bottom of the reaction column 14 through the upper circulation pipe 16, and the top of the reaction column 14 is connected to the bottom of the aeration column 15 through the lower circulation pipe. The inlet pipe 18 is arranged at the middle and lower part of the upper circulation pipe 16. The sewage to be treated is introduced into the loop pipe 16 through the inlet pipe 18. The outlet pipe 19 is arranged at the top of the reaction column 14 for discharging the treated sewage.
[0028] Aeration plate 20 is located at the bottom of aeration column 15. The air outlet of blower 13 is connected to aeration plate 20 via an aeration pipeline. Thus, when blower 13 pumps air through aeration plate 20 to the bottom of aeration column 15, the sewage at the bottom of aeration column 15 is oxygenated. The oxygenated sewage rises, raising not only the liquid level in aeration column 15 but also the liquid level in aeration column 15 above that in reaction column 14. Due to the liquid level difference, sewage at the top of aeration column 15 flows through upper circulation pipe 16 to the bottom of reaction column 14. Simultaneously, the density of sewage at the bottom of aeration column 15 decreases after aeration. Due to the pressure difference, sewage at the top of reaction column 14 flows partially through lower circulation pipe 17 to the top of aeration column 15, while a portion overflows and is discharged through outlet pipe 19. This achieves self-circulating flow during sewage treatment, eliminating the need for external forces and reducing energy consumption during the treatment process.
[0029] The operation control system consists of a PLC controller 9, a monitoring PC, online COD, online ammonia nitrogen 2, online No. 1 DO, online No. 1 SS, online No. 2 SS, online PH, online No. 2 DO, a liquid flow meter 5, a liquid reflux valve 11, a gas flow meter 8 and a gas solenoid valve 12. The PLC controller 9 has the functions of signal acquisition, data calculation and control output. The PLC controller 9 is connected to the monitoring PC via a communication optical fiber, and the monitoring PC is used to monitor the operation of the PLC controller 9.
[0030] The detection terminals for online COD, online ammonia nitrogen 2, online DO (No. 1), and online SS (No. 1) are located at the top of the reaction column 14. Their signal output terminals are connected to the input terminals of the PLC controller 9, allowing the controller to collect the chemical oxygen demand (COD), ammonia nitrogen concentration, dissolved oxygen concentration, and sludge concentration of the wastewater at the top of the reaction column 14. The detection terminals for online pH and online DO (No. 2) are located at the top of the aeration column 15. Their signal output terminals are connected to the input terminals of the PLC controller 9, allowing the controller to collect the pH and dissolved oxygen concentration of the wastewater at the top of the aeration column 15. The detection terminal for online SS (No. 2) is located at the top of the lower circulation pipe 17. Its signal output terminals are connected to the input terminals of the PLC controller 9, allowing the controller to collect the sludge concentration of the effluent from the reaction column 14 via online SS (No. 2).
[0031] A liquid flowmeter 5 is installed on the upper circulation pipe 16 between the water inlet pipe 18 and the aeration column 15 to detect the flow rate of sewage returning from the aeration column 15 to the bottom of the reaction column 14. A liquid reflux valve 11 is installed on the upper circulation pipe 16 between the water inlet pipe 18 and the reaction column 14 to control the reflux rate of sewage in the upper circulation pipe 16. A gas flowmeter 8 and a gas solenoid valve 12 are installed on the aeration pipeline between the blower 13 and the aeration plate 20 to detect and control the gas flow in the aeration pipeline, respectively. The signal output terminals of the liquid flowmeter 5 and the gas flowmeter 8 are connected to the input terminals of the PLC controller 9, and the output terminals of the PLC controller 9 are connected to the control terminals of the liquid reflux valve 11 and the gas solenoid valve 12. To achieve different opening control, the liquid reflux valve 11 and the gas solenoid valve 12 are respectively equipped with an electric liquid butterfly valve and an electric gas ball valve.
[0032] Online DO (DO) sensors 1 and 2 monitor the dissolved oxygen levels in the wastewater at the tops of the reaction column 14 and aeration column 15. By calculating the difference between the two, the oxygen supply and demand within the reactor can be determined. Online pH sensors monitor the pH level of the wastewater at the tops of the aeration column 15, while online SS sensors 1 monitor the sludge concentration in the wastewater at the tops of the reaction column 14 to determine the approximate location of the sludge bed. Online COD and online ammonia nitrogen sensors 2 monitor the COD (chemical oxygen demand) and ammonia nitrogen concentrations in the wastewater at the tops of the reaction column 14 in real time, thereby assessing the progress of the biochemical reaction within the reactor. Each monitoring sensor is connected to a PLC controller 9, transmitting its monitoring signals to the controller for logical analysis. After this logical analysis, the controller transmits control signals to the electric control unit, which controls and adjusts the opening of the liquid reflux valve 11 and the gas solenoid valve 12.
[0033] During normal operation, the sewage to be treated enters the upper circulation pipe 16 through the water inlet pipe 18. The inlet water mixes with the sewage returned from the upper circulation pipe 16 and enters the bottom of the reaction column 14. The sewage diffuses upward evenly in the reaction column 14 through the water distributor. When the upward water flow reaches a certain rising flow rate, it drives the granular sludge to expand, the sludge bed height increases, and the microorganisms in the granular sludge treat the sewage through biochemical reactions; part of the sewage at the top of the reaction column 14 flows into the bottom of the aeration column 15 through the lower circulation pipe 17, and part overflows and is discharged through the outlet pipe 19. The rising water flow of the reaction column 14 and some small particles with poor sedimentation performance flow into the aeration column 15 through the lower circulation pipe 17, and the overall circulation is driven by aeration.
[0034] First, the operation control system performs the functions of supervision and auxiliary operation. Each sensor records the operating status of the reactor in real time and transmits the data to the PLC controller 9 for recording. Second, the operation control system can optimize the operating conditions of the reactor in real time to achieve the purpose of reducing energy consumption and optimizing the operating effect. The operation control system determines the oxygen demand of the reactor through the oxygen supply and demand relationship between the reaction column 14 and the aeration column 15, thereby adjusting the aeration volume. The reaction progress in the reactor can be determined by the pollutant concentration in the reaction column. When the treatment effect is poor, the opening of the reflux pipe valve is increased to increase the circulation volume and accelerate the reaction to proceed fully.
[0035] The first priority of the operation control system is to maintain the stable operation of the reactor. Based on the monitoring of the online water quality indicators in the reactor, the PLC controller 9 and the monitoring PC perform real-time analysis of the online data, make real-time optimization and adjustment of the operating conditions of the reactor, and realize the intelligent operation of the reactor.
[0036] To maintain the stable operation of the sludge expansion bed in the reaction column 14, maintain the dissolved oxygen gradient in the reaction column 14, and reduce sludge loss, a stable sludge layer needs to be formed in the reaction column 14 during operation. The sludge concentration at the top of the reaction column 14 is monitored in real time by the online No. 1 SS. When the sludge concentration exceeds the preset concentration, the liquid reflux valve 11 and the gas solenoid valve 12 are used to adjust the reflux flow of the entire reactor to reduce the sludge layer. However, when the sludge concentration is lower than the preset value, the liquid reflux valve 11 and the gas solenoid valve 12 are used to adjust the reflux flow of the entire reactor to increase the sludge layer, so that the sludge layer is always maintained at a certain height in the reaction column 14 (determined by the position of the SS sensor).
[0037] The total nitrogen removal efficiency of the reactor is a key indicator of its operation, and optimizing it is a key goal of this control system. By controlling the liquid reflux valve 11 and the gas solenoid valve 12, respectively, the reactor's reflux and aeration rates are controlled, thereby controlling the oxygen supply within the reactor. Based on online feedback from ammonia nitrogen levels, the oxygen supply is adjusted in real time to maximize total nitrogen removal efficiency. As the influent volume and concentration fluctuate, the oxygen supply required by the reactor changes in real time. The system makes online decisions based on the built-in logic of the PLC controller 9, making timely adjustments to the liquid reflux valve 11 and the gas solenoid valve 12.
[0038] The operation control system is based on a split aeration self-circulating sludge expansion bed. All its treatment units are located in a large environment. If a problem occurs in a unit or link in the reactor, the operation status of the entire reactor will be affected. Therefore, real-time monitoring of the internal status of the reactor, as well as prediction of possible problems in the reactor in advance and preparation of treatment plans are required, as follows:
[0039] When reactor sludge sedimentation occurs, a large amount of sludge accumulates at the bottom of reaction column 14, hindering the biochemical reaction process and causing a sharp drop in dissolved oxygen consumption. The online dissolved oxygen concentration at the top of reaction column 14 increases, the online DO value significantly increases, the online SS concentration decreases, and the online ammonia nitrogen and COD concentrations also increase. For example, if the sludge concentration in the sewage above the reaction column is less than 1000 mg / L, the chemical oxygen demand (COD) is greater than 30 mg / L, and the ammonia nitrogen concentration is greater than 5 mg / L, it can be considered that sludge sedimentation has occurred at the bottom of reaction column 14.
[0040] The corresponding solution is for PLC controller 9 to respond as follows: It simultaneously increases the openings of liquid reflux valve 11 and gas solenoid valve 12 to expand aeration volume, increasing the pressure differential between aeration column 15 and reaction column 14 and promoting reflux. Simultaneously, the opening of liquid reflux valve 11 is increased, further increasing the upward flow velocity within reaction column 14 and raising the sludge layer height. Furthermore, the operation control system uses negative feedback to stabilize the sludge layer at a predetermined height, maintaining the upward flow velocity within a certain range.
[0041] When the influent concentration suddenly and sharply increases, the oxygen demand in reaction column 14 increases rapidly, causing the dissolved oxygen concentration in reaction column 14 to drop significantly. The online dissolved oxygen concentration above reaction column 14 decreases, and the online DO value decreases significantly. Without timely supplemental aeration, pollutants in reaction column 14 are no longer completely removed, and the online ammonia nitrogen and COD concentrations at the top of reaction column 14 increase. For example, when the ammonia nitrogen concentration in the wastewater at the top of the reaction column rises to greater than 5 mg / L and the online chemical oxygen demand (COD) concentration rises to greater than 30 mg / L, it can be considered that the pollutant concentration in the influent has increased sharply.
[0042] The corresponding solution is to have the PLC controller 9 control the liquid reflux valve 11 and the gas solenoid valve 12 to gradually increase their openings in a step-by-step manner, and to continuously adjust the openings of the liquid reflux valve 11 and the gas solenoid valve 12 based on real-time data from online detection equipment. Alternatively, the openings can be adjusted by reducing the water intake.
[0043] When the influent concentration drops sharply, the oxygen demand within the reactor decreases accordingly, and the oxygen supply is sufficient. The online dissolved oxygen in the upper portion of reaction column 14 rises rapidly, and the value of online DO1 increases significantly. Small amounts of pollutants are promptly removed before entering reaction column 14, and the online COD and online ammonia nitrogen concentrations are significantly lower than the preset values. For example, if the dissolved oxygen DO1 of the sewage at the top of the reaction column is detected to increase to 2×0.5 mg / L within 5 minutes, and the chemical oxygen demand COD and ammonia nitrogen concentration of the sewage at the top of the reaction column decrease to (30 mg / L) / 2 and (5 mg / L) / 2 within 5 minutes, it can be considered that the pollutant concentration in the influent has dropped sharply.
[0044] The corresponding treatment method is: in order to save aeration and reduce energy consumption, the opening of the gas solenoid valve 12 is reduced to appropriately reduce the aeration volume. At the same time, negative feedback adjustment of the aeration is performed on the online No. 1 DO in real time according to the online No. 1 SS and online dissolved oxygen concentration to prevent incomplete removal of pollutants caused by too low aeration and delayed aeration, and also to prevent the sludge layer from descending and depositing.
[0045] When the influent is abnormal, the pH6 of the influent differs significantly from the normal influent. For example, if the pH is lower than 6.5 or higher than 8, it indicates that pollutants that will destroy the activity of the granular sludge are present in the incoming sewage, causing a sudden change in the sludge properties. First, its concentration will slowly decrease, and the removal efficiency of its pollutants will be greatly reduced. The online COD and online ammonia nitrogen concentrations are high. In this case, simply adjusting the aeration and reflux rate will have limited effect. First, reduce the influent, then increase aeration, increase the opening of the liquid reflux valve 11 and the gas solenoid valve 12, and maximize the reflux ratio to flush the sludge and allow the sludge state to recover as self-regulatingly as possible.
Claims
1. A sewage treatment control method using an operation control system of a split aeration self-circulating sludge expansion bed, wherein the operation control system of the split aeration self-circulating sludge expansion bed is composed of a reactor and an operation control system, wherein the reactor is composed of a reaction column (14), an aeration column (15), a blower (13), an upper circulation pipe (16) and a lower circulation pipe (17), wherein the upper end of the aeration column is connected to the lower end of the reaction column via the upper circulation pipe, and the upper end of the reaction column is connected to the lower end of the aeration column via the lower circulation pipe, the middle and lower part of the upper circulation pipe is connected to a water inlet pipe (18), and the upper part of the reaction column is connected to a water outlet pipe (19); granular sludge for treating sewage is inoculated in the reaction column, an aeration plate (20) is provided at the bottom of the aeration column, and the blower is connected to the aeration plate via an aeration pipe; under the aeration action of the aeration plate, , the density of sewage at the bottom of the aeration column decreases and the liquid level rises, so that the sewage at the top of the aeration column flows into the bottom of the reaction column through the upper circulation pipe, and part of the sewage at the top of the reaction column flows into the bottom of the aeration column through the lower circulation pipe, and part of it overflows and is discharged through the outlet pipe, thereby realizing self-circulation flow in the sewage treatment process; the operation control system is composed of a PLC controller (9), online COD (1), online ammonia nitrogen (2), online No. 1 DO (3), online No. 1 SS (4), online No. 2 SS (21), online PH (6), online No. 2 DO (7), liquid reflux valve (11) and gas solenoid valve (12); the detection ends of online COD, online ammonia nitrogen, online No. 1 DO and online No. 1 SS are all placed at the top of the reaction column, and the signal output ends are all connected to the input end of the PLC controller; The detection ends of the online pH and online No. 2 DO are both placed at the top of the aeration column, and the signal output ends are connected to the input end of the PLC controller; the detection end of the online No. 2 SS is set at the upper end of the lower circulation pipe, and the signal output end is connected to the input end of the PLC controller; the gas solenoid valve is set on the aeration pipeline between the blower and the aeration disk, and the liquid reflux valve is set on the upper circulation pipe between the water inlet pipe and the reaction column. The control ends of the gas solenoid valve and the liquid reflux valve are both connected to the output end of the PLC controller; The PLC controller detects the COD, ammonia nitrogen, dissolved oxygen and sludge concentration of the sewage at the top of the reaction column through online COD, online ammonia nitrogen, online No. 1 DO and online No. 1 SS respectively. It also detects the pH and dissolved oxygen concentration of the sewage at the top of the aeration column through online pH and online No. 2 DO respectively. It detects the sludge concentration of the effluent from the reaction column through online No. 2 SS. Based on the detected values, the gas solenoid valve and liquid reflux valve are used to control and adjust the aeration volume and sewage reflux volume respectively, so as to control the reactor to automatically and normally perform sewage treatment. The sewage treatment control method of the operation control system of the split aeration self-circulating sludge expansion bed is characterized in that it is achieved by the following steps: a) Equipment operation: Start the operation control system, introduce the sewage to be treated through the water inlet pipe, turn on the blower, and the PLC controller opens the gas solenoid valve and liquid reflux valve. The blower aerates the sewage at the bottom of the aeration column through the aeration disk. Under the action of aeration, the sewage circulates between the aeration column and the reaction column. As the sewage enters the bottom of the reaction column, it causes the granular sludge to expand, causing the sludge bed in the reaction column to rise. The granular sludge in the sludge bed treats the sewage. b) Parameter collection: The PLC controller collects COD, ammonia nitrogen, dissolved oxygen, and sludge concentrations of the sewage at the top of the reaction column, as well as the pH and dissolved oxygen concentration of the sewage at the top of the aeration column, in real time. Based on the collected data, the controller controls the opening of the gas solenoid valve and liquid reflux valve to ensure that the COD, ammonia nitrogen, dissolved oxygen, and sludge concentrations of the sewage at the top of the reaction column, as well as the pH and dissolved oxygen concentrations of the sewage at the top of the aeration column, are within the set ranges, thereby achieving automatic control operation of the sewage treatment system. c) Oxygen supply and demand detection and control: The PLC controller collects the dissolved oxygen (DO1) of the sewage at the top of the reaction column through the online No. 1 DO meter. When the dissolved oxygen (DO1) is detected to be lower than 0.5 mg / L, indicating that the dissolved oxygen concentration of the sewage at the top of the reaction column is too low, the opening of the gas solenoid valve and the liquid reflux valve is increased to expand the aeration volume and increase the sewage return flow; Collect the dissolved oxygen DO2 of the sewage at the top of the aeration column through the online No. 2 DO meter and determine whether the dissolved oxygen DO2 value is within the range of [4mg / L~7mg / L]. If the dissolved oxygen DO2 is lower than 4mg / L, it indicates that the aeration is too low, and the opening of the gas solenoid valve is increased to increase the aeration volume; if the dissolved oxygen DO2 is higher than 7mg / L, it indicates that there is excessive aeration in the aeration column, and the opening of the gas solenoid valve is reduced to appropriately reduce the aeration; d) Pollutant concentration detection and control: The chemical oxygen demand (COD) of the wastewater at the top of the reaction column is detected online. If the COD is greater than 30 mg / L and the other parameters are normal, it indicates that the pollutant concentration in the wastewater at the top of the reaction column is too high. In this case, the opening of the liquid reflux valve is increased to increase the circulation volume and speed up the reaction. e-1). Sludge deposition detection and control. If a large amount of sludge accumulates at the bottom, it will hinder the biochemical reaction process and cause a sharp drop in dissolved oxygen consumption. When the sludge concentration in the sewage at the top of the reaction column detected by the online No. 1 SS is less than 1000 mg / L, the dissolved oxygen DO2 of the sewage at the top of the aeration column detected by the online No. 2 DO is greater than 0.5 mg / L, the chemical oxygen demand (COD) of the sewage at the top of the reaction column detected by the online COD is greater than 30 mg / L, and the ammonia nitrogen concentration of the sewage at the top of the reaction column detected by the online ammonia nitrogen is greater than 5 mg / L, it is determined that the granular sludge in the reaction column has deposited. In this case, the opening of the gas solenoid valve and the liquid reflux valve are increased simultaneously, the aeration volume is expanded, the pressure difference between the two columns is increased, the reflux is promoted, the rising flow rate of the sewage in the reaction column is increased, and the height of the sludge layer is increased. Through negative feedback regulation, the sludge layer in the reaction column can be stabilized at a preset height, and the rising flow rate of the sewage in the reaction column is also maintained within a certain range. e-2) Detection and control of excessive sludge: When the sludge concentration in the reaction column effluent detected by the online No. 2 SS is greater than 1000 mg / L and persists for more than 30 minutes, it indicates that the sludge layer in the reaction column is too high. This is not conducive to the biochemical reaction of the granular sludge on pollutants in the reaction column and may also cause sludge to enter the aeration column through the lower circulation pipe. In this case, the opening of the liquid reflux valve is reduced to reduce the rising flow rate of the sewage in the reaction column to reduce the height of the sludge layer in the reaction column. f). Detection and control of a sharp increase in influent concentration: When the online No. 1 DO detects that the dissolved oxygen (DO1) in the sewage at the top of the reaction column drops sharply within a short period of time, such as DO1 becoming 0 within 5 minutes, and the ammonia nitrogen concentration in the sewage at the top of the reaction column rises to greater than 5 mg / L, and the online chemical oxygen demand (COD) rises to greater than 30 mg / L, indicating a sharp increase in the pollutant concentration in the influent, the opening of the liquid reflux valve and the gas solenoid valve are controlled to increase in a step-by-step manner to increase the aeration volume and sewage reflux rate, thereby enhancing the reaction column's ability to treat pollutants; g). Detection and control of a sharp drop in influent concentration; When the pollutant concentration in the influent drops sharply, the oxygen demand in the reaction column decreases accordingly, and the oxygen supply is sufficient, and the online dissolved oxygen in the upper part of the reaction column rises rapidly. When the dissolved oxygen DO1 of the sewage at the top of the reaction column increases to 2×0.5 mg / L within 5 minutes, and at the same time, the chemical oxygen demand (COD) of the sewage at the top of the reaction column decreases to (30 mg / L) / 2 and the ammonia nitrogen concentration decreases to (5 mg / L) / 2 within 5 minutes, it indicates that the pollutant concentration in the influent has dropped sharply. To save aeration and reduce energy consumption, the aeration volume is appropriately reduced by reducing the opening of the gas solenoid valve; h). Detection and control of abnormal water inlet; determine whether the pH of the sewage at the top of the aeration column detected by the online pH is within the range of [6.5,8]. If the pH is lower than 6.5 or higher than 8, it indicates that pollutants that will destroy the activity of granular sludge are present in the incoming sewage. At this time, first reduce the water inlet volume, then increase the opening of the gas solenoid valve and liquid reflux valve, increase aeration and increase liquid reflux, improve the reflux ratio, flush the sludge, and restore the sludge state to self-regulation.
2. The sewage treatment control method of the operation control system of the split aeration self-circulating sludge expansion bed according to claim 1 is characterized by: The invention comprises a gas flow meter (8) and a liquid flow meter (5), wherein the liquid flow meter is arranged on the upper circulation pipe (16) between the water inlet pipe (18) and the aeration column (15), and the gas flow meter is arranged on the aeration pipeline between the blower (13) and the aeration plate (20), and the signal output ends of the gas flow meter and the liquid flow meter are both connected to the input end of the PLC controller.
3. The sewage treatment control method of the operation control system of the split aeration self-circulating sludge expansion bed according to claim 1 or 2 is characterized in that: The liquid reflux valve (11) is an electric liquid butterfly valve, and the gas solenoid valve (12) is an electric gas ball valve.
4. The sewage treatment control method of the operation control system of the split aeration self-circulating sludge expansion bed according to claim 1 or 2 is characterized in that: The PLC controller (9) is connected to a monitoring PC (10) via a communication optical fiber.
Citation Information
Patent Citations
Combined sewage denitrification process and device having automatic cyclic flowing function
CN105481210A