A denitrification and dephosphorization intelligent dosing control system and method for sewage treatment

Abstract

The application discloses a kind of nitrogen and phosphorus removal intelligent dosing control system and method for sewage treatment, belong to energy-saving and environmental protection technical field and sewage treatment technical field.The application only monitors the nitrate nitrogen concentration, phosphate concentration data in mixed liquor in SBR reactor, and the dosing amount and dosing time of carbon source and phosphorus removal reagent are calculated by mathematical model algorithm of intelligent dosing control system, while introducing cyclic execution control mode, to ensure that nitrate nitrogen, phosphate concentration reaches target value stably.The application realizes intelligent and fine control of SBR sewage treatment process reagent dosing under the condition of meeting effluent quality standard discharge, avoids the problem of excessive or insufficient reagent dosing amount, and improves the impact resistance and pollutant removal load capacity of SBR sewage treatment process to high nitrogen and phosphorus pollutants.The system and method not only realize stable and standard effluent quality and energy saving and consumption reduction, but also make SBR sewage treatment process more stable, more accurate and more intelligent.

Description

TECHNICAL FIELD

[0001] The present application relates to a denitrification and dephosphorization intelligent dosing control system and method for sewage treatment, belonging to the technical field of energy saving and environmental protection and the technical field of sewage treatment. BACKGROUND

[0002] With the rapid development of industrialization and urbanization, water pollution problems are becoming increasingly serious. Nitrogen and phosphorus are the main factors of water eutrophication, and effective control of the discharge of these pollutants is necessary to protect the water environment. Traditional sewage treatment methods often rely on manual operation, which is inefficient and prone to errors. Currently, there have been reports of some denitrification and dephosphorization systems or methods, but there is no denitrification and dephosphorization intelligent dosing control system and method for SBR (Sequencing Batch Reactor).

[0003] SBR is a sewage treatment process that operates in an intermittent aeration mode. The core of the process is the SBR reaction tank, which replaces the spatially divided operation mode with a time-division operation mode. The time-sequential operation process consists of five stages: water inlet, reaction, sedimentation, water outlet, and idle. From the start of water inlet to the end of idle, it constitutes a running cycle. Therefore, SBR process integrates homogenization, biodegradation, sedimentation and other functions, and does not require a secondary sedimentation tank and sludge return system. It is a relatively mature and widely recognized and used sewage treatment process.

[0004] The SBR sewage treatment process can perform biological denitrification and dephosphorization in a single SBR reaction tank by adjusting the operation mode. Biological denitrification is achieved by converting ammonia nitrogen in wastewater into nitrate nitrogen through nitrification by nitrifying bacteria under aerobic conditions, and then using nitrate nitrogen as an electron acceptor and organic matter as an electron donor for denitrification by denitrifying bacteria under anoxic conditions to convert nitrate nitrogen in wastewater into nitrogen gas, which escapes from the water, thereby achieving the purpose of biological denitrification. Biological dephosphorization is achieved by absorbing organic matter in wastewater by phosphorus accumulating organisms (PAOs) under anaerobic conditions and transporting it into the cell to assimilate it into intracellular carbon energy storage material PHB. The required capacity comes from the hydrolysis of polyphosphorus and the glycolysis of intracellular sugar, which leads to the release of phosphate. Then under aerobic conditions, the activity of PAOs is restored and excess phosphorus required for growth is stored in the form of polyphosphorus. PHB is oxidized and metabolized to produce energy for the excess absorption of phosphorus and the synthesis of polyphosphorus, and the form of polyphosphorus sludge. The purpose of biological dephosphorization is ultimately achieved by discharging the sludge. Generally, the biological dephosphorization effect of SBR sewage treatment process is poor, so chemical dephosphorization is usually combined with biological dephosphorization. Chemical dephosphorization is achieved by adding dephosphorization reagents to wastewater to react with phosphate in wastewater to form aluminum salt precipitates, which are then removed by discharging the sludge to achieve the purpose of dephosphorization.

[0005] Faced with increasingly stringent effluent discharge standards, sewage treatment plants add carbon sources and phosphorus removal agents during operation to further reduce pollutants such as nitrogen and phosphorus in sewage, in order to strengthen the removal of nitrogen and phosphorus and ensure that the effluent quality is stable and meets standards. Since the SBR sewage treatment process replaces the spatial division operation mode with the time division operation mode, the nitrification and denitrification processes are completed in different operation stages of a single SBR reaction tank, resulting in the inability to continuously add external agents. Agents need to be added under specific conditions in specific operation stages to achieve effective removal of pollutants and energy saving and consumption reduction. However, the current sewage treatment plant mainly adds carbon sources and phosphorus removal agents manually or with traditional automatic control. The following problems exist in the actual agent addition process:

[0006] (1) The carbon source is often added at the time point when aeration in the reaction stage of the operation cycle ends (pushing and stirring continues). At this time point, the dissolved oxygen concentration of the mixed liquor in the SBR reaction tank is between 2 and 4 mg / L, which is still in an aerobic environment. Part of the added carbon source is consumed by heterotrophic microorganisms, which not only causes ineffective loss of the added carbon source, but also produces a large amount of activated sludge, resulting in an increase in direct operating costs. After a period of continuous ineffective loss of carbon source and dissipation of dissolved oxygen, the dissolved oxygen concentration of the mixed liquor in the SBR reaction tank drops below 0.5 mg / L, and after reaching an anoxic environment, the denitrifying bacteria use the remaining carbon source for denitrification and denitrification.

[0007] (2) Since the cycle time of the SBR sewage treatment process and the time of each stage in each operation cycle can be flexibly adjusted according to the pollutant removal situation, the sewage treatment plant operators have weak professional skills and cannot make corresponding process adjustments according to the actual water inflow situation, making the operation time of each operation stage in a rough adjustment or constant state, resulting in the pollutant removal situation and the dosage of reagents cannot be accurately controlled;

[0008] (3) In order to ensure that the effluent water quality is stable and meets the standards, excessive dosage of chemicals is often used, which not only wastes the chemicals but also causes the effluent COD to exceed the standard. In addition, when the influent water quality fluctuates greatly, the dosage of the original carbon source and phosphorus removal chemicals may be insufficient. If manual intervention is not made to adjust the dosage of chemicals in time, the total nitrogen and total phosphorus indicators of the effluent will exceed the standards.

[0009] Therefore, it is necessary to provide an intelligent dosing control system and method for nitrogen and phosphorus removal in SBR wastewater treatment process. Summary of the Invention

[0010] To address the above issues, the present invention provides an intelligent dosing control system and method for nitrogen and phosphorus removal in sewage treatment processes. Based on the specific operating mode of the SBR sewage treatment process, the present invention does not consider feedforward influencing factors such as influent flow rate, influent total nitrogen concentration, and influent phosphate concentration. Instead, it monitors only the nitrate nitrogen and phosphate concentrations in the mixed liquor within the SBR reactor. The intelligent dosing control system calculates the dosage and time of the carbon source and phosphorus removal agent through a mathematical model algorithm. A cyclic execution control method is also introduced to ensure that the nitrate nitrogen and phosphate concentrations stably reach the target values. The present invention utilizes the flexibility of the SBR sewage treatment process to treat different water volumes and water qualities. Based on an online monitoring probe and a mathematical model algorithm, the intelligent dosing control system flexibly regulates the dosing pump. While ensuring that the effluent water quality meets the discharge standard, the system achieves intelligent and refined control of the SBR sewage treatment process's chemical dosing, avoiding the problem of excessive or insufficient chemical dosage. Compared with manual dosing or traditional automatic control dosing, the intelligent dosing control system can save more than 30% of the amount of phosphorus removal agent and carbon source added, while further improving the SBR sewage treatment process's impact resistance and pollutant removal capacity for high nitrogen and phosphorus pollutants. This system and method not only achieves stable effluent water quality and energy conservation and consumption reduction, but also makes the SBR sewage treatment process more stable, more precise, and more intelligent.

[0011] The first object of the present invention is to provide an intelligent dosing control system for nitrogen and phosphorus removal in an SBR sewage treatment process, comprising an SBR reactor module and an intelligent dosing control module;

[0012] SBR reactor module, including reactor, water inlet pump, blower, gas flow meter, aeration plate, stirrer, water outlet solenoid valve, and sludge pump;

[0013] The reactor is a right quadrangular prism reactor containing a microbial mixture that removes organic matter, nitrogen and phosphorus under specific conditions in a specific operating stage;

[0014] The water inlet pump is connected to the reactor through a water inlet pipe;

[0015] The blower and the gas flow meter are located outside the reactor, and the gas flow meter is connected to the blower and the reactor respectively through an air pipe. The aeration plate is located at the bottom of the reactor, and the aeration plate is connected to the gas flow meter outside the reactor through an air pipe. The blower provides air to the microbial mixture in the reactor through the air pipe and the aeration plate, thereby creating aerobic conditions for the microbial mixture.

[0016] The stirrer is located inside the reactor and is used to stir the microbial mixture, the incoming water, and the added reagents to make them fully mixed;

[0017] The water outlet solenoid valve is located outside the reactor and is connected to the reactor via a water outlet pipe;

[0018] The sludge pump is located outside the reactor and is connected to the reactor via a sludge pipeline.

[0019] Intelligent dosing control module, including online nitrate nitrogen probe, online phosphate probe, online dissolved oxygen probe, online ammonia nitrogen probe, PLC control cabinet, carbon source electromagnetic flowmeter, carbon source variable frequency dosing pump, phosphorus removal agent electromagnetic flowmeter, phosphorus removal agent variable frequency dosing pump.

[0020] The online nitrate nitrogen probe, the online phosphate probe, the online dissolved oxygen probe, and the online ammonia nitrogen probe are located inside the reactor and immersed in the mixed liquid of the reactor, wherein the online nitrate nitrogen probe is used to monitor the nitrate nitrogen concentration in the mixed liquid in the reactor; the online phosphate probe is used to monitor the phosphate concentration in the mixed liquid in the reactor; the online dissolved oxygen probe is used to monitor the dissolved oxygen concentration in the mixed liquid in the reactor; and the online ammonia nitrogen probe is used to monitor the ammonia nitrogen concentration in the mixed liquid in the reactor;

[0021] The data monitored by the online nitrate nitrogen probe, the online phosphate probe, the online dissolved oxygen probe, and the online ammonia nitrogen probe are transmitted to the PLC control cabinet through a signal line. The PLC control cabinet is located outside the reactor. The PLC control cabinet calculates the monitoring data through a mathematical model algorithm of the carbon source and the dephosphorization agent to obtain the agent dosage volume.

[0022] The carbon source electromagnetic flowmeter, the carbon source variable frequency dosing pump, the phosphorus removal agent electromagnetic flowmeter, and the phosphorus removal agent variable frequency dosing pump are located outside the reactor. The carbon source electromagnetic flowmeter is connected to the carbon source variable frequency dosing pump and the reactor respectively through a dosing pipeline. The phosphorus removal agent electromagnetic flowmeter is connected to the phosphorus removal agent variable frequency dosing pump and the reactor respectively through a dosing pipeline. The carbon source electromagnetic flowmeter and the phosphorus removal agent electromagnetic flowmeter are used to measure the flow rate of the carbon source and the phosphorus removal agent. The flow rates measured by the carbon source electromagnetic flowmeter and the phosphorus removal agent electromagnetic flowmeter are transmitted to the PLC control cabinet through a signal line. The PLC control cabinet calculates the flow data through the mathematical model algorithm of the carbon source and the phosphorus removal agent to obtain the addition time of the agent.

[0023] The electrical signals of the carbon source variable frequency dosing pump and the phosphorus removal agent variable frequency dosing pump are connected to the PLC control cabinet through signal lines. The PLC control cabinet controls the start and stop of the carbon source variable frequency dosing pump and the phosphorus removal agent variable frequency dosing pump according to the agent dosage and dosage time obtained by the mathematical model algorithm.

[0024] A second object of the present invention is to provide an intelligent dosing method for denitrification and phosphorus removal in an SBR wastewater treatment process based on the above-mentioned intelligent denitrification and phosphorus removal control system, comprising the following steps:

[0025] Step 1: The core of the SBR sewage treatment process is the reaction tank body. The operation process in chronological order is water inlet (stirring), reaction (aeration and stirring), sedimentation, water outlet, and idle stage. From the start of water inlet to the end of idle stage, an operation cycle is formed.

[0026] Step 2: Entering the water inlet stage (stirring), the water inlet pump injects sewage into the reactor, and at the same time starts the agitator for continuous stirring, so that the inlet water and the mixed liquid in the reactor are in contact and mixed, and the water inlet is stopped after the reactor is filled with water. At this time, the liquid level height is H. During the water inlet stage (stirring), the mixed liquid in the reactor is in an oxygen-deficient environment. Since the inlet water contains a certain amount of organic matter, the denitrifying bacteria in the mixed liquid in the reactor will use the biodegradable organic matter in the inlet water to convert the residual nitrate nitrogen in the mixed liquid into nitrogen gas. The residual nitrate nitrogen concentration in the mixed liquid in the reactor will gradually decrease as the water inlet stage (stirring) continues, until the PLC control cabinet monitors the nitrate nitrogen concentration in the mixed liquid in the reactor through the online nitrate nitrogen probe and drops to 0 mg / L, or remains unchanged, and then the water inlet stage (stirring) is ended;

[0027] Step 3: Entering the reaction (aeration and stirring) stage, starting the blower, injecting air into the aeration disk in the reactor through the air pipe, the air enters the mixed liquid through the aeration disk, and the mixed liquid in the reactor changes from an anoxic environment to an aerobic environment. The nitrifying bacteria in the mixed liquid in the reactor convert ammonia nitrogen in the sewage into nitrate nitrogen through nitrification under aerobic conditions. The ammonia nitrogen concentration in the mixed liquid in the reactor will gradually decrease as the reaction (aeration and stirring) stage continues until the PLC control cabinet monitors that the ammonia nitrogen concentration in the mixed liquid in the reactor drops to 1 mg / L through the online ammonia nitrogen probe, and the reaction (aeration and stirring) stage is terminated;

[0028] Step 4: Entering the reaction (stirring) stage, the blower is turned off, and the stirrer is continued to operate to keep the mixed liquid in the reactor in a uniform state. The PLC control cabinet monitors the concentrations of dissolved oxygen, nitrate nitrogen, and phosphate in the mixed liquid in the reactor in real time through an online dissolved oxygen probe, an online nitrate nitrogen probe, and an online phosphate probe.

[0029] Step 5: Establish a mathematical model algorithm to calculate the dosage and addition time of carbon source and phosphorus removal agent.

[0030] Step 6: The specific calculation method of the mathematical model for phosphorus removal agent addition is as follows:

[0031]

[0032] In formula (1), V represents the volume of the phosphorus removal agent solution; β represents the phosphorus removal agent addition coefficient, when Ps≤Pc, β takes the value 0, when Ps>4, β takes the value 1, when 2

[0033] In formula (2), Q represents the flow of the phosphorus removal agent feeding pump, and T represents the feeding time of the phosphorus removal agent feeding pump.

[0034] The phosphorus removal agent feeding pump start-stop logic takes the reaction (stirring) stage as the premise, takes the PLC control cabinet phosphorus removal agent mathematical model algorithm as the core, obtains the phosphorus removal agent addition amount V and the addition time T according to the phosphate concentration in the mixed liquid monitored by the online phosphate probe, then adjusts the frequency of the phosphorus removal agent feeding pump, matches the flow Q of the phosphorus removal agent feeding pump, then starts the phosphorus removal agent feeding pump, adds the phosphorus removal agent to the reactor at the flow Q, after the phosphorus removal agent feeding pump adds for T time, the phosphorus removal agent feeding pump is closed, the phosphate in the mixed liquid in the reactor reacts with the phosphorus removal agent to generate aluminum salt precipitate, then sludge is discharged in the idle stage, so as to achieve the purpose of phosphorus removal.

[0035] Step 7: During the reaction (stirring) stage, since the blower has just been turned off, dissolved oxygen still remains in the mixed liquid in the reactor, so that the mixed liquid in the reactor is still in an aerobic environment, and nitrifying bacteria continue to consume the residual dissolved oxygen through nitrification, while constantly stirring to allow the dissolved oxygen to escape into the air, until the PLC control cabinet monitors the dissolved oxygen concentration in the mixed liquid in the reactor through the online dissolved oxygen probe and drops below 0.5 mg / L, the aerobic environment of the mixed liquid in the reactor will become an anoxic environment, thereby providing a denitrification and denitrification environment. Under anoxic conditions, the denitrifying bacteria in the mixed liquid in the reactor use an external carbon source as an electron donor to carry out denitrification, converting nitrate nitrogen in the sewage into nitrogen gas, which escapes from the water, thereby achieving the purpose of biological denitrification. The specific calculation method of the mathematical model for carbon source addition is as follows:

[0036]

[0037] In formula (3), V represents the volume of carbon source solution, α represents the carbon source addition coefficient, when Ns≤Nc, α is 0, when the water temperature is <17℃, α=6, when 17≤water temperature<20℃, α=5.5, when 20≤water temperature<23℃, α=5, when 23≤water temperature<26℃, α=4.5, when 26℃≤water temperature, α=4; Ns represents the nitrate nitrogen concentration last monitored by the online nitrate nitrogen probe before adding the carbon source in the reaction (stirring) stage, Nc represents the target nitrate nitrogen concentration in the effluent, S represents the cross-sectional area of ​​the reactor, H represents the liquid level height after the reactor is filled with water, C d Indicates the COD equivalent of the carbon source.

[0038] In formula (4), Q represents the flow rate of the carbon source dosing pump, and T represents the dosing time of the carbon source dosing pump.

[0039] The start and stop logic of the carbon source dosing pump is based on the reaction (stirring) stage and the dissolved oxygen concentration in the mixed liquid in the reactor in this stage, and is centered on the carbon source mathematical model algorithm of the PLC control cabinet. The carbon source dosage V and the dosing time T are obtained according to the nitrate nitrogen concentration in the mixed liquid monitored by the online nitrate nitrogen probe. When the PLC control cabinet monitors that the dissolved oxygen concentration in the mixed liquid in the reactor is below 0.5 mg / L through the online dissolved oxygen probe, the frequency of the carbon source dosing pump is adjusted to match the flow rate Q of the carbon source dosing pump, and then the carbon source dosing pump is started to add carbon source to the reactor at the flow rate Q. After the carbon source dosing pump finishes the dosing time T, the carbon source dosing pump is turned off.

[0040] Step 8: Before adding the phosphorus removal agent or carbon source, the PLC control cabinet follows the following control logic:

[0041] When the SBR wastewater treatment process is in the reaction (stirring) stage, execute step six formulas (1) and (2);

[0042] When the SBR wastewater treatment process is in the reaction (stirring) stage and the DO in the mixed liquid in the reactor is less than 0.5 mg / L, execute formulas (3) and (4) in step seven;

[0043] Step 9: After the phosphorus removal agent and carbon source are added at one time, the mixed liquid in the reactor, the phosphorus removal agent and the carbon source are fully stirred in the agitator to undergo chemical phosphorus removal and biological denitrification, thereby removing phosphate and nitrate nitrogen from the sewage. The online phosphate probe monitors the phosphate concentration Ps' in the mixed liquid, and the online nitrate nitrogen probe monitors the nitrate nitrogen concentration Ns' in the mixed liquid, which show a continuous decrease. After decreasing to a constant level, the PLC control cabinet follows the following control logic:

[0044] When the online phosphate probe detects that the phosphate concentration Ps' in the mixed solution decreases to a constant level and Ps'-Pc ≤ 10% Pc, step six is ​​completed.

[0045] When the online phosphate probe detects that the phosphate concentration Ps' in the mixed solution decreases to a constant level, if Ps'-Pc>10%Pc, the loop execution mode of step six formulas (1) and (2) is entered until Ps'-Pc≤10%Pc, indicating that the loop execution mode ends and step six execution ends;

[0046] When the online nitrate nitrogen probe detects that the nitrate nitrogen concentration Ns' in the mixed solution decreases to a constant level and Ns'-Nc ≤ 5% Nc, step seven is completed.

[0047] When the online nitrate nitrogen probe detects that the nitrate nitrogen concentration Ns' in the mixed solution decreases to a constant level, and if Ns'-Nc>5%Pc, the loop execution mode of step seven formulas (1) and (2) is entered until Ns'-Nc≤5%Nc, indicating that the loop execution mode ends and step seven execution ends;

[0048] When Ps'-Pc≤10%Pc and Ns'-Nc≤5%Nc, the stirrer is stopped, and the reaction (stirring) stage is ended;

[0049] Step 10: Entering the sedimentation stage, turning off the agitator, and allowing the activated sludge in the mixed liquid in the reactor to naturally settle to the bottom of the reactor under the action of gravity, thereby separating the clarified supernatant from the activated sludge. After maintaining a static state for 60 minutes, the sedimentation stage is ended.

[0050] Step 11: Start entering the water discharge stage, open the water discharge solenoid valve, discharge the supernatant in the reactor, and close the water discharge solenoid valve after the liquid level in the reactor drops to h, stop draining, and end the water discharge stage.

[0051] Step 12: Entering the idle stage, starting the sludge discharge pump according to the sludge age and sludge concentration requirements to discharge a certain amount of excess sludge. After the sludge discharge is completed, the sludge discharge pump is closed and the next cycle is awaited.

[0052] Step 13: Starting from step 2 and ending with step 12, it constitutes a complete operation cycle of the SBR sewage treatment process, and then the cycle is repeated.

[0053] Beneficial effects of the present invention:

[0054] (1) Effectively solve the ineffective loss of carbon source caused by the residual dissolved oxygen in the mixed liquid at the end of aeration (stirring) in the reaction stage of the SBR sewage treatment process. The intelligent dosing control system flexibly adjusts and controls the carbon source dosing pump to ensure the addition of carbon source in an oxygen-deficient environment, thereby achieving energy saving and consumption reduction.

[0055] (2) Not only does the effluent quality meet the standards stably, but also the phosphorus removal agent and carbon source are intelligently added on demand, avoiding the problem of excessive or insufficient agent addition, and realizing intelligent and refined control of agent addition in the SBR sewage treatment process. Compared with manual addition or traditional automatic control addition, the intelligent dosing control system can save more than 30% of the amount of phosphorus removal agent and carbon source added.

[0056] (3) Intelligent dosing control system, which accurately calculates the dosage of reagents according to the pollutant concentration in the reactor mixture and intelligently adjusts the reaction time of each reaction (stirring) stage according to the pollutant removal situation, thereby improving the SBR wastewater treatment process's ability to withstand shocks of high nitrogen and phosphorus pollutants and its pollutant removal load capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic diagram of the overall system structure connection in one embodiment of the present invention.

[0058] Figure 2 Schematic diagram of the operation phase cycle in one embodiment of the present invention.

[0059] In the figure, 1: reactor, 2: water inlet pump, 3: air blower, 4: gas flow meter, 5: aeration disc, 6: stirrer, 7: water outlet solenoid valve, 8: sludge pump, 9: online nitrate nitrogen probe, 10: online phosphate probe, 11: online dissolved oxygen probe, 12: online ammonia nitrogen probe, 13: PLC control cabinet, 14: carbon source electromagnetic flow meter, 15: carbon source variable frequency dosing pump, 16: phosphorus removal agent electromagnetic flow meter, 17: phosphorus removal agent variable frequency dosing pump, 18: water inlet stage (stirring), 19: reaction stage (aeration stirring), 20: reaction stage (stirring), 21: precipitation stage, 22: water outlet stage, 23: idle stage.

[0060] Figure 3 The figure is the change graph of the concentration of TN in the influent and effluent in the actual sewage treatment in Example 2.

[0061] Figure 4 The figure is the change graph of the concentration of TP in the influent and effluent in the actual sewage treatment in Example 2. DETAILED DESCRIPTION

[0062] Example 1: Denitrification and phosphorus removal intelligent dosing control system for SBR and its use method

[0063] As shown in Figure 1 and Figure 2 , it is a schematic diagram of the overall system structure connection and the operation stage cycle of the application.

[0064] The application provides a denitrification and phosphorus removal intelligent dosing control system for a sewage treatment process. It comprises an SBR reactor module and an intelligent dosing control module.

[0065] The SBR reactor module comprises a reactor 1, a water inlet pump 2, an air blower 3, a gas flow meter 4, an aeration disc 5, a stirrer 6, a water outlet solenoid valve 7 and a sludge pump 8.

[0066] The reactor 1 is a straight four-pyramid reactor, and the reactor 1 contains a microbial mixed solution, and organic matter, nitrogen and phosphorus are removed under specific conditions in specific operation stages.

[0067] The water inlet pump 2 is connected to the reactor 1 through a water inlet pipeline.

[0068] The air blower 3 and the gas flow meter 4 are located outside the reactor 1, the gas flow meter 4 is connected to the air blower 3 and the reactor 1 through an air pipeline respectively, the aeration disc 5 is located at the bottom of the reactor 1, and the aeration disc 5 is connected to the gas flow meter 4 outside the reactor 1 through an air pipeline, and the air blower 3 provides air to the microbial mixed solution in the reactor 1 through an air pipeline and the aeration disc 5, thereby creating an aerobic condition for the microbial mixed solution.

[0069] The stirrer 6 is located inside the reactor 1 and is used to stir the microbial mixture, the incoming water, and the added reagents to make them fully mixed;

[0070] The water outlet solenoid valve 7 is located outside the reactor 1 and is connected to the reactor 1 through a water outlet pipe;

[0071] The sludge pump 8 is located outside the reactor 1 and is connected to the reactor 1 through a sludge pipeline.

[0072] The intelligent dosing control module includes an online nitrate nitrogen probe 9, an online phosphate probe 10, an online dissolved oxygen probe 11, an online ammonia nitrogen probe 12, a PLC control cabinet 13, a carbon source electromagnetic flowmeter 14, a carbon source variable frequency dosing pump 15, a phosphorus removal agent electromagnetic flowmeter 16, and a phosphorus removal agent variable frequency dosing pump 17.

[0073] The online nitrate nitrogen probe 9, the online phosphate probe 10, the online dissolved oxygen probe 11, and the online ammonia nitrogen probe 12 are located inside the reactor 1 and immersed in the mixed liquid of the reactor 1, wherein the online nitrate nitrogen probe 9 is used to monitor the nitrate nitrogen concentration in the mixed liquid in the reactor 1; the online phosphate probe 10 is used to monitor the phosphate concentration in the mixed liquid in the reactor 1; the online dissolved oxygen probe 11 is used to monitor the dissolved oxygen concentration in the mixed liquid in the reactor 1; the online ammonia nitrogen probe 12 is used to monitor the ammonia nitrogen concentration in the mixed liquid in the reactor 1;

[0074] The data monitored by the online nitrate nitrogen probe 9, the online phosphate probe 10, the online dissolved oxygen probe 11, and the online ammonia nitrogen probe 12 are transmitted to the PLC control cabinet 13 through a signal line. The PLC control cabinet 13 is located outside the reactor 1. The PLC control cabinet 13 calculates the monitoring data through the mathematical model algorithm of the carbon source and the dephosphorization agent to obtain the agent dosage volume.

[0075] The carbon source electromagnetic flowmeter 14, the carbon source variable frequency dosing pump 15, the phosphorus removal agent electromagnetic flowmeter 16, and the phosphorus removal agent variable frequency dosing pump 17 are located outside the reactor 1. The carbon source electromagnetic flowmeter 14 is connected to the carbon source variable frequency dosing pump 15 and the reactor 1 respectively through a dosing pipeline. The phosphorus removal agent electromagnetic flowmeter 16 is connected to the phosphorus removal agent variable frequency dosing pump 17 and the reactor 1 respectively through a dosing pipeline. The carbon source electromagnetic flowmeter 14 and the phosphorus removal agent electromagnetic flowmeter 16 are used to measure the flow rate of the carbon source and the phosphorus removal agent. The flow rate measured by the carbon source electromagnetic flowmeter 14 and the phosphorus removal agent electromagnetic flowmeter 16 is transmitted to the PLC control cabinet 13 through a signal line. The PLC control cabinet 13 calculates the flow data through the mathematical model algorithm of the carbon source and the phosphorus removal agent to obtain the addition time of the agent.

[0076] The signals of the carbon source variable frequency dosing pump 15 and the phosphorus removal agent variable frequency dosing pump 17 are connected to the PLC control cabinet 13 through signal lines. The PLC control cabinet 13 controls the start and stop of the carbon source variable frequency dosing pump 15 and the phosphorus removal agent variable frequency dosing pump 17 according to the agent dosage and dosage time obtained by the mathematical model algorithm.

[0077] An intelligent dosing method for denitrification and phosphorus removal for sewage treatment based on the above-mentioned intelligent control system for denitrification and phosphorus removal in sewage treatment comprises the following steps:

[0078] Step 1: The core of the SBR sewage treatment process is the reactor 1. The operation process in chronological order is water inlet (stirring), reaction (aeration and stirring), sedimentation, water outlet, and idle. One operation cycle is from the start of water inlet to the end of idle.

[0079] Step 2: Entering the water inlet stage (stirring) 18, the water inlet pump 2 injects sewage into the reactor 1, and at the same time starts the agitator 6 for continuous stirring, so that the incoming water and the mixed liquid in the reactor 1 are in contact and mixed. When the reactor 1 is filled with water, the water inlet is stopped, and the liquid level height is H. During the water inlet stage (stirring) 18, the mixed liquid in the reactor 1 is in an anoxic environment. Since the inlet water contains a certain amount of organic matter, the denitrifying bacteria in the mixed liquid in the reactor 1 will use the biodegradable organic matter in the inlet water to convert the residual nitrate nitrogen in the mixed liquid into nitrogen gas. The residual nitrate nitrogen concentration in the mixed liquid in the reactor 1 will gradually decrease as the water inlet stage (stirring) 18 continues, until the PLC control cabinet 13 monitors the nitrate nitrogen concentration in the mixed liquid in the reactor 1 through the online nitrate nitrogen probe 9 and drops to 0 mg / L, or remains unchanged (if there is enough organic matter in the inlet water, the nitrate nitrogen will react completely, and the concentration will drop to 0 mg / L; if there is insufficient organic matter in the inlet water, the nitrate nitrogen will not react completely. After dropping to a certain concentration, it will remain unchanged because the organic matter in the inlet water is consumed), and then the water inlet stage (stirring) 18 is ended;

[0080] Step 3: Entering the reaction (aeration and stirring) stage 19, starting the blower 3, injecting air into the aeration disk 5 in the reactor 1 through the air pipe, and the air enters the mixed liquid through the aeration disk 5. The mixed liquid in the reactor 1 changes from an anoxic environment to an aerobic environment. The nitrifying bacteria in the mixed liquid in the reactor 1 convert ammonia nitrogen in the sewage into nitrate nitrogen through nitrification under aerobic conditions. The ammonia nitrogen concentration in the mixed liquid in the reactor 1 gradually decreases as the reaction (aeration and stirring) stage 19 continues until the PLC control cabinet 13 monitors that the ammonia nitrogen concentration in the mixed liquid in the reactor drops to 1 mg / L through the online ammonia nitrogen probe 12, and the reaction (aeration and stirring) stage 19 ends;

[0081] Step 4: Entering the reaction (stirring) stage 20, the blower 3 is turned off, and the stirrer 6 is continued to operate to keep the mixed liquid in the reactor 1 in a uniform state. The PLC control cabinet 13 monitors the dissolved oxygen, nitrate nitrogen, and phosphate concentrations in the mixed liquid in the reactor in real time through the online dissolved oxygen probe 11, the online nitrate nitrogen probe 9, and the online phosphate probe 10.

[0082] Step 5: Establish a mathematical model algorithm to calculate the dosage and addition time of carbon source and phosphorus removal agent.

[0083] Step 6: The specific calculation method of the mathematical model for phosphorus removal agent addition is as follows:

[0084]

[0085] In formula (1), V represents the volume of phosphorus removal agent solution; β represents the phosphorus removal agent dosage coefficient. When Ps≤Pc, β takes a value of 0; when Ps>4, β takes a value of 1; when 2<Ps≤4, β takes a value of 1.5; when 1<Ps≤2, β takes a value of 2; when 0.5<Ps≤1, β takes a value of 4; when 0.4<Ps≤0.5, β takes a value of 6; when 0.3<Ps≤0.4, β takes a value of 8; when 0.2<Ps≤1, β takes a value of 1. When s≤0.3, β takes a value of 12; when 0.15<Ps≤0.2, β takes a value of 16; when Ps≤0.15, β takes a value of 20; Ps represents the phosphate concentration last monitored by the online phosphate probe 10 before adding the dephosphorization agent in the reaction (stirring) stage 20; Pc represents the target phosphate concentration in the effluent; S represents the cross-sectional area of ​​the reactor 1 (if the reactor is cylindrical, the cross-sectional area is πR 2 If the reactor is a cube or a cuboid, the cross-sectional area is length × width); H represents the liquid level height after the reactor 1 is filled with water; M represents the molar mass of the aluminum element in the dephosphorization agent, e represents the effective content of effective aluminum in the dephosphorization agent solution (unit: %), and ρ represents the density of the dephosphorization agent solution.

[0086] In formula (2), Q represents the flow rate of the dephosphorization agent dosing pump 17, and T represents the dosing time of the dephosphorization agent dosing pump 17.

[0087] The start and stop logic of the dephosphorization agent dosing pump 17 is based on the reaction (stirring) stage 20 and the dephosphorization agent mathematical model algorithm of the PLC control cabinet 13 as the core. The dephosphorization agent dosage V and the addition time T are obtained according to the phosphate concentration in the mixed liquid monitored by the online phosphate probe 10, and then the frequency of the dephosphorization agent dosing pump 17 is adjusted to match the dephosphorization agent dosing pump flow Q. Then, the dephosphorization agent dosing pump 17 is started to add dephosphorization agent to the reactor 1 at a flow rate Q. After the dephosphorization agent dosing pump 17 has added for T time, the dephosphorization agent dosing pump 17 is turned off. The phosphate in the mixed liquid in the reactor 1 reacts chemically with the dephosphorization agent to generate aluminum salt precipitate, and then sludge is discharged in the idle stage 23, thereby achieving the purpose of dephosphorization.

[0088] Step seven: In the reaction (stirring) stage 20, since the blower 3 has just been turned off, dissolved oxygen still remains in the mixed liquid in the reactor 1, so that the mixed liquid in the reactor 1 is still in an aerobic environment, and nitrifying bacteria continue to consume the residual dissolved oxygen through nitrification, while constantly stirring to allow the dissolved oxygen to escape into the air, until the PLC control cabinet 13 monitors the dissolved oxygen concentration in the mixed liquid in the reactor 1 through the online dissolved oxygen probe 11 and drops to below 0.5 mg / L, the aerobic environment of the mixed liquid in the reactor 1 will become an anoxic environment, thereby providing a denitrification and denitrification environment. Under anoxic conditions, the denitrifying bacteria in the mixed liquid in the reactor 1 use an external carbon source as an electron donor to carry out denitrification, converting nitrate nitrogen in the sewage into nitrogen gas, which escapes from the water, thereby achieving the purpose of biological denitrification. The specific calculation method of the mathematical model of carbon source addition is as follows:

[0089]

[0090] In formula (3), V represents the volume of carbon source solution added, α represents the carbon source addition coefficient; when Ns≤Nc, α is 0; when Ns is greater than Nc, the value of α is related to the water temperature, when the water temperature is <17°C, α=6, when 17≤water temperature<20°C, α=5.5, when 20≤water temperature<23°C, α=5, when 23≤water temperature<26°C, α=4.5, when 26°C≤water temperature, α=4; Ns represents the nitrate nitrogen concentration last monitored by the online nitrate nitrogen probe 9 before the carbon source is added in the reaction (stirring) stage 20, Nc represents the target nitrate nitrogen concentration in the effluent, S represents the cross-sectional area of ​​the reactor 1, H represents the liquid level height after the reactor is filled with water, C d Indicates the COD equivalent of the carbon source.

[0091] In formula (4), Q represents the flow rate of the carbon source dosing pump 15, and T represents the dosing time of the carbon source dosing pump 15.

[0092] The start and stop logic of the carbon source dosing pump 15 is based on the reaction (stirring) stage 20 and the dissolved oxygen concentration in the mixed liquid in the reactor 1 in this stage, and is centered on the carbon source mathematical model algorithm of the PLC control cabinet 13. The carbon source dosage V and the addition time T are obtained according to the nitrate nitrogen concentration in the mixed liquid monitored by the online nitrate nitrogen probe 9. When the dissolved oxygen concentration in the mixed liquid in the reactor 1 is below 0.5 mg / L monitored by the online dissolved oxygen probe 11 in the PLC control cabinet 13, the frequency of the carbon source dosing pump 15 is adjusted to match the flow rate Q of the carbon source dosing pump, and then the carbon source dosing pump 15 is started to add carbon source to the reactor 1 at the flow rate Q. After the carbon source dosing pump 15 adds the carbon source for the time T, the carbon source dosing pump 15 is turned off.

[0093] Step 8: Before adding the dephosphorization agent or carbon source, the PLC control cabinet 13 follows the following selection logic:

[0094] When the SBR wastewater treatment process is in the reaction (stirring) stage 20, execute step six formulas (1) and (2);

[0095] When the SBR sewage treatment process is in the reaction (stirring) stage 20, and the PLC control cabinet 13 detects that the DO in the mixed liquid in the reactor 1 is less than 0.5 mg / L through the online dissolved oxygen probe 11, step seven formulas (3) and (4) are executed; when DO ≥ 0.5, step seven is not executed;

[0096] Step 9: After the phosphorus removal agent and carbon source are added at one time, the mixed liquid in the reactor 1, the phosphorus removal agent and the carbon source are fully stirred in the stirrer 6 to undergo chemical phosphorus removal and biological denitrification, thereby removing phosphate and nitrate nitrogen from the sewage. The online phosphate probe 10 monitors the phosphate concentration Ps' in the mixed liquid, and the online nitrate nitrogen probe 9 monitors the nitrate nitrogen concentration Ns' in the mixed liquid, which show a continuous decrease. After the decrease remains unchanged, the PLC control cabinet 13 follows the following control logic:

[0097] When the phosphate concentration Ps' in the mixed solution detected by the online phosphate probe 10 decreases to a constant level and Ps'-Pc ≤ 10% Pc, step six is ​​completed.

[0098] When the online phosphate probe 10 detects that the phosphate concentration Ps' in the mixed solution decreases to a constant level, if Ps'-Pc>10%Pc, the loop execution mode of step six formulas (1) and (2) is entered until Ps'-Pc≤10%Pc, indicating that the loop execution mode ends and step six execution ends;

[0099] When the online nitrate nitrogen probe 9 detects that the nitrate nitrogen concentration Ns' in the mixed liquid decreases to a constant level and Ns'-Nc ≤ 5% Nc, step seven is completed.

[0100] When the online nitrate nitrogen probe 9 detects that the nitrate nitrogen concentration Ns' in the mixed solution decreases to a constant level, if Ns'-Nc>5%Pc, the loop execution mode of step seven formulas (1) and (2) is entered until Ns'-Nc≤5%Nc, which indicates that the loop execution mode ends and step seven execution ends;

[0101] When Ps'-Pc≤10%Pc and Ns'-Nc≤5%Nc, the stirrer 6 is stopped, and the reaction (stirring) stage 20 is ended;

[0102] Step 10: Entering the sedimentation stage 21, turning off the agitator 6, the activated sludge in the mixed liquid in the reactor 1 naturally settles to the bottom of the reactor 1 under the action of gravity, thereby separating the clarified supernatant from the activated sludge. After the sedimentation stage 21 remains in a static state for 60 minutes, the sedimentation stage 21 ends.

[0103] Step 11: Start entering the water outlet stage 22, open the water outlet solenoid valve 7, and discharge the supernatant in the reactor 1. After the liquid level in the reactor 1 drops to h, close the water outlet solenoid valve 7, stop draining, and end the water outlet stage 22.

[0104] Step 12: Entering the idle stage 23, starting the sludge pump 8 according to the sludge age and sludge concentration requirements to discharge a certain amount of excess sludge. After the sludge discharge is completed, the sludge pump 8 is closed and the next cycle is awaited.

[0105] Step 13: Starting from step 2 and ending with step 12, it constitutes a complete operation cycle of the SBR sewage treatment process, and then the cycle is repeated.

[0106] Example 2:

[0107] The intelligent dosing control system for nitrogen and phosphorus removal and the method of use of Example 1 are used for actual sewage treatment.

[0108] A chemical wastewater treatment project has a designed water treatment capacity of 150 tons / day and adopts the SBR main process. The dimensions of the SBR tank are length × width × height = 15m × 7.5m × 5m. The designed inlet and outlet water quality of the project is shown in Table 1.

[0109] Table 1 Designed inlet and outlet water quality of a chemical wastewater treatment project (mg / L)

[0110] index COD <![CDATA[NH4 + -N]]> TN TP Influent water quality 350 45 55 5 Outlet water quality 50 5 15 0.5

[0111] According to the sewage treatment system design, the TN of the effluent is 15 mg / L, of which NH4 + -N is 5mg / L. Due to the characteristics of chemical wastewater, the actual concentration of organic nitrogen in the effluent is less than 0.5mg / L. Therefore, the effluent nitrate nitrogen concentration should not exceed 9.5mg / L, and the control effluent nitrate nitrogen Nc concentration is set to 8mg / L. According to the sewage treatment system design, the effluent TP is 0.5mg / L. Due to the characteristics of chemical wastewater, the actual concentration of organic phosphorus in the effluent is less than 0.1mg / L. Therefore, the effluent phosphate concentration should not exceed 0.4mg / L, and the control effluent phosphate Pc concentration is set to 0.25mg / L.

[0112] During the denitrification and phosphorus removal process of sewage treatment, the added carbon source is sodium acetate with a COD equivalent of 200,000 mg.L; the main component of the added phosphorus removal agent solution is polyaluminum chloride PAC, with an effective aluminum content of 10%, and the density of the phosphorus removal agent solution is 1.12 g / cm 3 .

[0113] The following steps are used to implement the intelligent dosing control system for nitrogen and phosphorus removal and its use method, as follows:

[0114] Step 1: Start entering the water inlet stage (stirring) 18, the water inlet pump 2 injects slaughterhouse wastewater into the reactor 1, and at the same time starts the stirrer 6 for continuous stirring, so that the slaughterhouse wastewater and the mixed liquid in the reactor 1 are in contact and mixed, and the water inlet is stopped after the reactor 1 is filled with water. At this time, the liquid level height is 4.5m. During the water inlet stage (stirring) 18, the mixed liquid in the reactor 1 is in an oxygen-deficient environment. Since the inlet water contains a certain amount of organic matter, the denitrifying bacteria in the mixed liquid in the reactor 1 will use the biodegradable organic matter in the inlet water to convert the residual nitrate nitrogen in the mixed liquid into nitrogen gas. The residual nitrate nitrogen concentration in the mixed liquid in the reactor 1 will gradually decrease as the water inlet stage (stirring) 18 continues, until the PLC control cabinet 13 monitors the nitrate nitrogen concentration in the mixed liquid in the reactor 1 through the online nitrate nitrogen probe 9 and drops to 0 mg / L, or remains unchanged, and then the water inlet stage (stirring) 18 is ended;

[0115] Step 2: Entering the reaction (aeration and stirring) stage 19, starting the blower 3, injecting air into the aeration disk 5 in the reactor 1 through the air pipe, and the air enters the mixed liquid through the aeration disk 5. The mixed liquid in the reactor 1 changes from an anoxic environment to an aerobic environment. The nitrifying bacteria in the mixed liquid in the reactor 1 convert ammonia nitrogen in the sewage into nitrate nitrogen through nitrification under aerobic conditions. The ammonia nitrogen concentration in the mixed liquid in the reactor 1 gradually decreases as the reaction (aeration and stirring) stage 19 continues until the PLC control cabinet 13 monitors that the ammonia nitrogen concentration in the mixed liquid in the reactor drops to 1 mg / L through the online ammonia nitrogen probe 12, and the reaction (aeration and stirring) stage 19 ends;

[0116] Step 3: Entering the reaction (stirring) stage 20, the blower 3 is turned off, and the stirrer 6 is continued to operate to keep the mixed liquid in the reactor 1 in a uniform state. The PLC control cabinet 13 monitors the dissolved oxygen, nitrate nitrogen, and phosphate concentrations in the mixed liquid in the reactor in real time through the online dissolved oxygen probe 11, the online nitrate nitrogen probe 9, and the online phosphate probe 10.

[0117] Step 4: Use mathematical model algorithms to calculate the dosage and addition time of carbon source and phosphorus removal agent.

[0118] Step 5: The specific calculation method of the mathematical model for phosphorus removal agent addition is as follows:

[0119]

[0120]

[0121] In formula (1), V represents the volume of phosphorus removal agent solution; β represents the phosphorus removal agent dosage coefficient. When Ps≤Pc, β takes a value of 0; when Ps>4, β takes a value of 1; when 2<Ps≤4, β takes a value of 1.5; when 1<Ps≤2, β takes a value of 2; when 0.5<Ps≤1, β takes a value of 4; when 0.4<Ps≤0.5, β takes a value of 6; when 0.3<Ps≤0.4, β takes a value of 8; when 0.2<Ps≤0.3, β takes a value of 12; when 0.15< When Ps≤0.2, β takes a value of 16; when Ps≤0.15, β takes a value of 20; Ps represents the phosphate concentration finally monitored by the online phosphate probe 10 before adding the dephosphorization agent in the reaction (stirring) stage 20; Pc represents the target phosphate concentration of the effluent, and the target phosphate concentration of the effluent is set to 0.25 mg / L in this implementation; S represents the cross-sectional area of ​​the reactor 1. The length and width dimensions of the SBR tank in this implementation project are 15m×7.5m, and S is 112.5m 2H represents the liquid level height of 4.5m after the reactor 1 is filled with water; M represents the molar mass of the aluminum element in the dephosphorization agent, 27g / mol; e represents the effective content of effective aluminum in the dephosphorization agent in the dephosphorization agent solution, 10%; ρ represents the density of the dephosphorization agent solution, 1.12g / cm 3 .

[0122] In formula (2), Q represents the flow rate of the dephosphorization agent dosing pump 17, and T represents the dosing time of the dephosphorization agent dosing pump 17.

[0123] The start and stop logic of the dephosphorization agent dosing pump 17 is based on the reaction (stirring) stage 20 and the dephosphorization agent mathematical model algorithm of the PLC control cabinet 13 as the core. The dephosphorization agent dosage V and the addition time T are obtained according to the phosphate concentration in the mixed liquid monitored by the online phosphate probe 10, and then the frequency of the dephosphorization agent dosing pump 17 is adjusted to match the dephosphorization agent dosing pump flow Q. Then, the dephosphorization agent dosing pump 17 is started to add dephosphorization agent to the reactor 1 at a flow rate Q. After the dephosphorization agent dosing pump 17 has added for T time, the dephosphorization agent dosing pump 17 is turned off. The phosphate in the mixed liquid in the reactor 1 reacts chemically with the dephosphorization agent to generate aluminum salt precipitate, and then sludge is discharged in the idle stage 23, thereby achieving the purpose of dephosphorization.

[0124] Step six: In the reaction (stirring) stage 20, since the blower 3 has just been turned off, dissolved oxygen still remains in the mixed liquid in the reactor 1, so that the mixed liquid in the reactor 1 is still in an aerobic environment, and nitrifying bacteria continue to consume the residual dissolved oxygen through nitrification, while constantly stirring to allow the dissolved oxygen to escape into the air, until the PLC control cabinet 13 monitors the dissolved oxygen concentration in the mixed liquid in the reactor 1 through the online dissolved oxygen probe 11 and drops to below 0.5 mg / L, the aerobic environment of the mixed liquid in the reactor 1 will become an anoxic environment, thereby providing a denitrification and denitrification environment. Under anoxic conditions, the denitrifying bacteria in the mixed liquid in the reactor 1 use an external carbon source as an electron donor to carry out denitrification, converting nitrate nitrogen in the sewage into nitrogen gas, which escapes from the water, thereby achieving the purpose of biological denitrification. The specific calculation method of the mathematical model for carbon source addition is as follows:

[0125]

[0126]

[0127] In formula (3), V represents the volume of carbon source solution added, α represents the carbon source addition coefficient; when Ns≤Nc, α takes a value of 0; when Ns is greater than Nc, the value of α is related to the water temperature, when the water temperature is <17°C, α=6, when 17≤water temperature<20°C, α=5.5, when 20≤water temperature<23°C, α=5, when 23≤water temperature<26°C, α=4.5, when 26°C≤water temperature, α=4; Ns represents the nitrate nitrogen concentration last monitored by the online nitrate nitrogen probe 9 before the carbon source is added in the reaction (stirring) stage 20, Nc represents the target concentration of nitrate nitrogen in the effluent, and the target concentration of nitrate nitrogen in the effluent is set to 8 mg / L in this implementation; S represents the cross-sectional area of ​​the reactor 1, the length and width of the SBR tank body of this implementation project are 15m×7.5m, and S is 112.5m 2 ; H represents the liquid level height of 4.5m after the reactor is filled with water, C d Indicates that the COD equivalent of the carbon source is 200,000 mg / L.

[0128] In formula (4), Q represents the flow rate of the carbon source dosing pump 15, and T represents the dosing time of the carbon source dosing pump 15.

[0129] The start and stop logic of the carbon source dosing pump 15 is based on the reaction (stirring) stage 20 and the dissolved oxygen concentration in the mixed liquid in the reactor 1 in this stage, and is centered on the carbon source mathematical model algorithm of the PLC control cabinet 13. The carbon source dosage V and the addition time T are obtained according to the nitrate nitrogen concentration in the mixed liquid monitored by the online nitrate nitrogen probe 9. When the dissolved oxygen concentration in the mixed liquid in the reactor 1 is below 0.5 mg / L monitored by the online dissolved oxygen probe 11 in the PLC control cabinet 13, the frequency of the carbon source dosing pump 15 is adjusted to match the flow rate Q of the carbon source dosing pump, and then the carbon source dosing pump 15 is started to add carbon source to the reactor 1 at the flow rate Q. After the carbon source dosing pump 15 adds the carbon source for the time T, the carbon source dosing pump 15 is turned off.

[0130] Step 7: Before adding the dephosphorization agent or carbon source, the PLC control cabinet 13 follows the following selection logic:

[0131] When the SBR wastewater treatment process is in the reaction (stirring) stage 20, execute step six formulas (1) and (2);

[0132] When the SBR sewage treatment process is in the reaction (stirring) stage 20, and the PLC control cabinet 13 monitors the DO in the mixed liquid in the reactor 1 through the online dissolved oxygen probe 11 to be less than 0.5 mg / L, step seven formulas (3) and (4) are executed;

[0133] Step 8: After the phosphorus removal agent and carbon source are added at one time, the mixed liquid in the reactor 1, the phosphorus removal agent and the carbon source are fully stirred in the stirrer 6 to undergo chemical phosphorus removal and biological denitrification, thereby removing phosphate and nitrate nitrogen from the sewage. The online phosphate probe 10 monitors the phosphate concentration Ps' in the mixed liquid, and the online nitrate nitrogen probe 9 monitors the nitrate nitrogen concentration Ns' in the mixed liquid, which show a continuous decrease. After the decrease remains unchanged, the PLC control cabinet 13 follows the following control logic:

[0134] When the phosphate concentration Ps' in the mixed solution detected by the online phosphate probe 10 decreases to a constant level and Ps'-Pc ≤ 10% Pc, step six is ​​completed.

[0135] When the online phosphate probe 10 detects that the phosphate concentration Ps' in the mixed solution decreases to a constant level, if Ps'-Pc>10%Pc, the loop execution mode of step six formulas (1) and (2) is entered until Ps'-Pc≤10%Pc, indicating that the loop execution mode ends and step six execution ends;

[0136] When the online nitrate nitrogen probe 9 detects that the nitrate nitrogen concentration Ns' in the mixed liquid decreases to a constant level and Ns'-Nc ≤ 5% Nc, step seven is completed.

[0137] When the online nitrate nitrogen probe 9 detects that the nitrate nitrogen concentration Ns' in the mixed solution decreases to a constant level, if Ns'-Nc>5%Pc, the loop execution mode of step seven formulas (1) and (2) is entered until Ns'-Nc≤5%Nc, which indicates that the loop execution mode ends and step seven execution ends;

[0138] When Ps'-Pc≤10%Pc and Ns'-Nc≤5%Nc, the stirrer 6 is stopped, and the reaction (stirring) stage 20 is ended;

[0139] Step 9: Start entering the sedimentation stage 21, turn off the agitator 6, and the activated sludge in the mixed liquid in the reactor 1 naturally settles to the bottom of the reactor 1 under the action of gravity, thereby separating the clarified supernatant from the activated sludge. After the sedimentation stage 21 remains in a static state for 60 minutes, the sedimentation stage 21 ends.

[0140] Step 10: Start entering the water outlet stage 22, open the water outlet solenoid valve 7, discharge the supernatant in the reactor 1, and close the water outlet solenoid valve 7 after the liquid level in the reactor 1 drops to h, stop draining, and end the water outlet stage 22.

[0141] Step 11: Entering the idle stage 23, starting the sludge pump 8 according to the sludge age and sludge concentration requirements to discharge a certain amount of excess sludge. After the sludge discharge is completed, the sludge pump 8 is closed and the next cycle is awaited.

[0142] Step 12: Starting from step 2 and ending at step 12, it constitutes a complete operation cycle of the SBR sewage treatment process, and then the cycle is repeated.

[0143] The project uses the intelligent dosing control system for denitrification and phosphorus removal and the total nitrogen and phosphorus in the inlet and outlet water before and after use. Figure 3 and Figure 4 As shown. According to the total nitrogen and total phosphorus concentrations in the effluent, from the 1st day to the 30th day, using traditional automatic control, the maximum total nitrogen concentration in the effluent was 12.03 mg / L, the minimum was 2.33 mg / L, and the average was 6.5 mg / L. The total nitrogen concentration in the effluent fluctuated greatly and showed a positive correlation with the total nitrogen in the inlet. The maximum total phosphorus in the effluent was 0.16 mg / L, the minimum was 0.04 mg / L, and the average was 0.10 mg / L. The total phosphorus concentration in the effluent fluctuated slightly and was far below the target control value, indicating that the phosphorus removal agent was over-dosed, resulting in agent waste. After the intelligent dosing control system was adopted on the 31st day, the effluent water quality fluctuated less, with the maximum total nitrogen in the effluent being 8.63 mg / L, the minimum being 7.82 mg / L, and the average being 8.23 ​​mg / L. The maximum total phosphorus in the effluent was 0.29 mg / L, the minimum being 0.20 mg / L, and the average being 0.25 mg / L. The total nitrogen and phosphorus concentrations in the effluent are generally maintained around the target control values, achieving on-demand intelligent dosing. In terms of operating costs, the use of the intelligent dosing control system for nitrogen and phosphorus removal allows the dosage of carbon source and phosphorus removal agents to be adjusted on demand, significantly reducing agent costs by 35% compared to traditional automatic control systems.

[0144] Table 2 Comparison of the effects of the intelligent dosing control system of the present invention and traditional automatic control

[0145] Control method Carbon source usage (L) Carbon source saving ratio Phosphorus removal agent usage (L) Phosphorus removal agent saving ratio Traditional automatic control 956 / 424 / Intelligent dosing control 650 32％ 238 43.87％

[0146] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for sewage treatment, characterized in that: include: The core of the SBR sewage treatment process is the reaction tank. The operation process in chronological order is divided into five operating stages: stirring water inlet, reaction, sedimentation, water discharge, and idle. One operating cycle is formed from the start of water inlet to the end of idle. The reaction is aerated stirring reaction first, and then stirred reaction; Among them, during the stirring reaction stage, a mathematical model algorithm is established to calculate the dosage and addition time of the carbon source and phosphorus removal agent; The specific calculation method of the mathematical model for phosphorus removal agent addition is as follows: In formula (1), V represents the volume of phosphorus removal agent solution; β represents the phosphorus removal agent dosage coefficient, when Ps≤Pc, β is 0, when Ps>4, β is 1, when 2<Ps≤4, β is 1.5, when 1<Ps≤2, β is 2, when 0.5<Ps≤1, β is 4, when 0.4<Ps≤0.5, β is 6, when 0.3<Ps≤0.4, β is 8, when 0.2<Ps≤0.3, β is 12, when 0.15<Ps≤0.2, β is 16, when Ps≤0.15, β is 20; Ps represents the phosphate concentration last monitored by the online phosphate probe before adding the phosphorus removal agent in the stirring reaction stage; Pc represents the target phosphate concentration of the effluent; S represents the cross-sectional area of ​​the reactor; H represents the liquid level height after the reactor is filled with water; M represents the molar mass of the aluminum element in the phosphorus removal agent; e represents the effective content of effective aluminum in the phosphorus removal agent solution; and ρ represents the density of the phosphorus removal agent solution. In formula (2), Q represents the flow rate of the dephosphorization agent dosing pump, and T represents the dosing time of the dephosphorization agent dosing pump; The specific calculation method of the carbon source addition mathematical model is as follows: In formula (3), V represents the volume of carbon source solution, α represents the carbon source addition coefficient, when Ns≤Nc, α is 0, when the water temperature is <17℃, α=6, when 17≤water temperature<20℃, α=5.5, when 20≤water temperature<23℃, α=5, when 23≤water temperature<26℃, α=4.5, when 26℃≤water temperature, α=4; Ns represents the nitrate nitrogen concentration last monitored by the online nitrate nitrogen probe before adding the carbon source in the stirring reaction stage, Nc represents the target nitrate nitrogen concentration in the effluent, S represents the cross-sectional area of ​​the reactor, H represents the liquid level height after the reactor is filled with water, C d Indicates the COD equivalent of the carbon source; In formula (4), Q represents the flow rate of the carbon source dosing pump, and T represents the dosing time of the carbon source dosing pump; The PLC control cabinet monitors the dissolved oxygen concentration in the mixed liquid in the reactor through the online dissolved oxygen probe and finds that it is below 0.5 mg / L, so it adjusts the frequency of the carbon source dosing pump to match the flow rate Q of the carbon source dosing pump.

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