Nitrogen and phosphorus removal intelligent dosing control system and method for sewage treatment

Abstract

The invention discloses a nitrogen and phosphorus removal intelligent dosing control system and method for sewage treatment, and belongs to the technical field of energy conservation and environmental protection and the technical field of sewage treatment. Only nitrate nitrogen concentration and phosphate concentration data in a mixed solution in the SBR reactor are monitored, the adding amount and adding time of a carbon source and a dephosphorization agent are calculated through a mathematical model algorithm of the intelligent agent adding control system, meanwhile, a circulating execution control mode is introduced, and it is ensured that the nitrate nitrogen concentration and the phosphate concentration stably reach target values. According to the invention, under the condition that the effluent quality reaches the standard for discharge, intelligent and fine control of SBR sewage treatment process agent feeding is realized, the problem of excessive or insufficient agent feeding amount is avoided, and meanwhile, the anti-impact bearing capacity and pollutant removal load capacity of the SBR sewage treatment process to high nitrogen and phosphorus pollutants are improved. According to the system and the method, the effluent quality is stable and reaches the standard, the energy is saved, the consumption is reduced, and the SBR sewage treatment process is more stable, more accurate and more intelligent.

Description

Technical Field

[0001] The invention relates to an intelligent dosing control system and method for denitrification and dephosphorization for sewage treatment, belonging to the technical fields of energy conservation and environmental protection and sewage treatment. Background Art

[0002] With the rapid development of industrialization and urbanization, water pollution is becoming increasingly serious. Nitrogen and phosphorus are the main factors of eutrophication of water bodies. Effectively controlling the discharge of these pollutants can protect the water environment. Traditional sewage treatment methods often rely on manual operations, which are inefficient and prone to errors. At present, some systems or methods for nitrogen and phosphorus removal have been reported, but there is no intelligent dosing control system and method for nitrogen and phosphorus removal in 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 uses a time-division operation mode instead of a space-division operation mode. The time sequence operation process is five operation stages: water inlet, reaction, sedimentation, water outlet, and idle. An operation cycle is formed from the beginning of water inlet to the end of idle. Therefore, the SBR process integrates homogenization, biodegradation, sedimentation and other functions, and does not require the setting of a secondary sedimentation tank and a sludge return system. It is a relatively mature and widely recognized and used sewage treatment process.

[0004] The SBR sewage treatment process can carry out biological denitrification and phosphorus removal in a single SBR reaction tank by adjusting the operation mode. Biological denitrification is that nitrifying bacteria convert ammonia nitrogen in sewage into nitrate nitrogen through nitrification under aerobic conditions, and then denitrifying bacteria use nitrate nitrogen as an electron acceptor and organic matter as an electron donor to carry out denitrification under anoxic conditions, converting nitrate nitrogen in sewage into nitrogen gas, which escapes from the water, thereby achieving the purpose of biological denitrification. Biological phosphorus removal is a process under anaerobic conditions where polyphosphate bacteria absorb organic matter in sewage and transport it into cells, where it is assimilated into intracellular carbon energy storage material PHB. The required capacity comes from the hydrolysis of polyphosphate and the fermentation of intracellular sugars, which leads to the release of phosphate. Then, under aerobic conditions, the activity of polyphosphate bacteria is restored, and the amount of phosphorus exceeding the growth requirement is stored in the form of polyphosphate. Energy is generated through the oxidative metabolism of PHB, which is used for excess phosphorus absorption and polyphosphate synthesis, and forms polyphosphate sludge. Ultimately, the purpose of biological phosphorus removal is achieved through the discharge of sludge. Generally, the biological phosphorus removal effect of SBR sewage treatment process is poor, and chemical phosphorus removal is usually combined with biological phosphorus removal. Chemical phosphorus removal is to add phosphorus removal agents to sewage, which react chemically with phosphates in the sewage to form aluminum salt precipitates, and then the purpose of phosphorus removal is achieved through the discharge of sludge.

[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 the 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 effectively remove pollutants and save energy and reduce consumption. However, the current sewage treatment plant mainly adds carbon sources and phosphorus removal agents manually or with traditional automatic control. In the actual agent addition process, the following problems exist:

[0006] (1) The carbon source is often added at the end of aeration in the reaction phase of the operation cycle (continue plug flow stirring). 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. The added carbon source is partially 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. 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 inability to accurately control the pollutant removal situation and the dosage of reagents;

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

[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] In order to solve the above problems, the present invention provides a denitrification and dephosphorization intelligent dosing control system and method for sewage treatment process. Based on the particularity of the operation mode of the SBR sewage treatment process, the present invention does not need to consider the feedforward influencing factors such as the influent flow rate, the influent total nitrogen concentration, and the influent phosphate concentration. It only monitors the nitrate nitrogen concentration and phosphate concentration data in the mixed liquid in the SBR reactor, calculates the dosage and addition time of the carbon source and the dephosphorization agent through the mathematical model algorithm of the intelligent dosing control system, and introduces a cyclic execution control mode to ensure that the nitrate nitrogen and phosphate concentrations stably reach the target value. The present invention utilizes the flexibility of the SBR sewage treatment process to treat different water quantities and water qualities. The intelligent dosing control system based on the online monitoring probe and the mathematical model algorithm flexibly regulates the dosing pump. Under the condition that the effluent water quality meets the discharge standard, the intelligent and refined control of the SBR sewage treatment process reagent addition is realized to avoid the problem of excessive or insufficient dosage of the reagent. Compared with manual addition or traditional automatic control addition, the intelligent dosing control system can save more than 30% of the phosphorus removal agent and carbon source dosage, and further improve the impact resistance and pollutant removal load capacity of the SBR sewage treatment process for high nitrogen and phosphorus pollutants. The system and method not only achieve stable effluent water quality and energy saving and consumption reduction, but also make the SBR sewage treatment process more stable, more accurate 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 mud pump;

[0013] The reactor is a straight quadrangular prism reactor, which contains a microbial mixture to remove organic matter, nitrogen and phosphorus under specific conditions in a specific operating stage;

[0014] The water inlet pump is connected to the reactor via 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 pipeline. 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 pipeline. The blower provides air to the microbial mixed liquid in the reactor through the air pipeline and the aeration plate to create aerobic conditions for the microbial mixed liquid.

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

[0017] The water outlet solenoid valve is located outside the reactor and 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 a carbon source and a 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 dosage 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] The second object of the present invention is to provide an intelligent dosing method for denitrification and phosphorus removal in an SBR sewage treatment process based on the above-mentioned intelligent control system for denitrification and phosphorus removal, 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 five operation stages: water inlet (stirring), reaction (aeration stirring, stirring), sedimentation, water outlet, and idle. One operation cycle is formed from the start of water inlet to the end of idle.

[0026] Step 2: Entering the water inlet stage (stirring), the water inlet pump injects sewage into the reactor, and the stirrer is started 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 certain 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. Drop to 0mg / L, or remain unchanged, and then end the water inlet stage (stirring);

[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 duct, the air enters the mixed liquid through the aeration disk, the mixed liquid in the reactor changes from an anaerobic 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 ended;

[0028] Step 4: Entering the reaction (stirring) stage, turning off the blower, and continuing to operate the stirrer to keep the mixed liquid in the reactor in a mixed 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 time of carbon source and phosphorus removal agent.

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

[0031]

[0032] 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 is 16, and when Ps≤0.15, β is 20; Ps represents the phosphate concentration finally monitored by the online phosphate probe before adding the dephosphorization agent in the reaction (stirring) 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 dephosphorization agent, e represents the effective content of the effective aluminum in the dephosphorization agent solution, and ρ represents the density of the dephosphorization agent solution.

[0033] 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.

[0034] The start and stop logic of the phosphorus removal agent dosing pump is based on the reaction (stirring) stage and the phosphorus removal agent mathematical model algorithm of the PLC control cabinet as the core. The phosphorus removal 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, and then the phosphorus removal agent dosing pump frequency is adjusted to match the phosphorus removal agent dosing pump flow Q, and then the phosphorus removal agent dosing pump is started to add phosphorus removal agent to the reactor at a flow rate Q. After the phosphorus removal agent dosing pump has added the phosphorus removal agent for T time, the phosphorus removal agent dosing pump is turned off, and the phosphate in the mixed liquid in the reactor reacts chemically with the phosphorus removal agent to generate aluminum salt precipitate, and then sludge is discharged during the idle stage, thereby achieving 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 continuously 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 to drop 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°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 finally 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 outlet water, S represents the cross-sectional area of ​​the reactor, H represents the liquid level height after the reactor is filled with water, and 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 at this stage, with the carbon source mathematical model algorithm of the PLC control cabinet as the core, and 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. 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 ends the addition 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 sewage 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 7;

[0043] Step 9: After the phosphorus removal agent and carbon source are added once, the mixed liquid in the reactor, the phosphorus removal agent and the carbon source undergo chemical phosphorus removal and biological denitrification under the condition of sufficient stirring in the agitator, and the phosphate and nitrate nitrogen in the sewage are removed. 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 remain constant and Ps'-Pc ≤ 10% Pc, it indicates that step six is ​​completed;

[0045] When the online phosphate probe detects that the phosphate concentration Ps' in the mixed solution decreases to remain constant, if Ps'-Pc>10%Pc, the loop execution mode of step six formulas (1) and (2) is entered until Ps'-Pc≤10%Pc, which indicates 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 remain constant and Ns'-Nc ≤ 5% Nc, it means that step seven is completed;

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

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

[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 outlet stage, open the water outlet solenoid valve, discharge the supernatant in the reactor, and close the water outlet solenoid valve after the liquid level in the reactor drops to h, stop draining, and end the water outlet 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 residual sludge, and closing the sludge discharge pump after the sludge discharge is completed, waiting for the start of the next cycle.

[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 carbon source dosing pump is flexibly adjusted and controlled by the intelligent dosing control system 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 standard stably, but also the phosphorus removal agent and carbon source are intelligently added on demand to avoid the problem of excessive or insufficient agent addition, and to achieve 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 phosphorus removal agent and carbon source addition.

[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 (mixing) 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 It 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: blower, 4: gas flow meter, 5: aeration plate, 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 flowmeter, 15: carbon source variable frequency dosing pump, 16: phosphorus removal agent electromagnetic flowmeter, 17: phosphorus removal agent variable frequency dosing pump, 18: water inlet stage (stirring), 19: reaction stage (aeration and stirring), 20: reaction stage (stirring), 21: sedimentation stage, 22: water outlet stage, 23: idle stage.

[0060] Figure 3 This is a graph showing the change in TN concentration of the inlet and outlet water during actual sewage treatment in Example 2.

[0061] Figure 4 This is a graph showing the changes in TP concentration of inlet and outlet water during actual sewage treatment in Example 2. DETAILED DESCRIPTION

[0062] Example 1: Intelligent dosing control system for nitrogen and phosphorus removal in SBR and its use method

[0063] like Figure 1 and Figure 2 The figure shows a schematic diagram of the overall system structure connection and a schematic diagram of the operation phase cycle of the present invention.

[0064] The present invention provides an intelligent dosing control system for nitrogen removal and phosphorus removal for sewage treatment process, including an SBR reactor module and an intelligent dosing control module:

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

[0066] The reactor 1 is a straight quadrangular prism reactor, and contains a microbial mixture to remove organic matter, nitrogen and phosphorus under specific conditions in a specific operating stage;

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

[0068] The blower 3 and the gas flow meter 4 are located outside the reactor 1, and the gas flow meter 4 is connected to the blower 3 and the reactor 1 respectively through an air pipe. The aeration plate 5 is located at the bottom of the reactor 1, and the aeration plate 5 is connected to the gas flow meter 4 outside the reactor 1 through an air pipe. The blower 3 provides air to the microbial mixed liquid in the reactor 1 through the air pipe and the aeration plate 5 to create aerobic conditions for the microbial mixed liquid;

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

[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 dephosphorization agent electromagnetic flowmeter 16, and a dephosphorization 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 contained in the mixed liquid in the reactor 1; the online phosphate probe 10 is used to monitor the phosphate concentration contained in the mixed liquid in the reactor 1; the online dissolved oxygen probe 11 is used to monitor the dissolved oxygen concentration contained in the mixed liquid in the reactor 1; the online ammonia nitrogen probe 12 is used to monitor the ammonia nitrogen concentration contained 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 through a dosing pipeline, and the phosphorus removal agent electromagnetic flowmeter 16 is connected to the phosphorus removal agent variable frequency dosing pump 17 and the reactor 1 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 rates measured by the carbon source electromagnetic flowmeter 14 and the phosphorus removal agent electromagnetic flowmeter 16 are 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 dosage 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 denitrification and phosphorus removal intelligent control system of the sewage treatment process 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 includes five operation stages: water inlet (stirring), reaction (aeration stirring, stirring), sedimentation, water outlet, and idle. One operation cycle is formed from the start of water inlet to the end of idle.

[0079] Step 2: Start entering the water inlet stage (stirring) 18, the water inlet pump 2 injects sewage into the reactor 1, and starts the stirrer 6 for continuous stirring, so that the incoming water 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 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 not enough organic matter in the inlet water, the nitrate nitrogen will not react completely, and 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 ends;

[0080] Step 3: Start to enter the reaction (aeration and stirring) stage 19, start the blower 3, inject air into the aeration disk 5 in the reactor 1 through the air pipe, the air enters the mixed liquid through the aeration disk 5, the mixed liquid in the reactor 1 changes from an anaerobic environment to an aerobic environment, the nitrifying bacteria in the mixed liquid in the reactor 1 convert the 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 will gradually decrease as the reaction (aeration and stirring) stage 19 continues, until the PLC control cabinet 13 monitors the ammonia nitrogen concentration in the mixed liquid in the reactor through the online ammonia nitrogen probe 12 to drop to 1 mg / L, and the reaction (aeration and stirring) stage 19 ends;

[0081] Step 4: Start to enter the reaction (stirring) stage 20, turn off the blower 3, and continue to operate the stirrer 6 to keep the mixed liquid in the reactor 1 in a mixed state. The PLC control cabinet 13 monitors the concentrations of dissolved oxygen, nitrate nitrogen and phosphate 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 time of carbon source and phosphorus removal agent.

[0083] Step 6: The specific calculation method of the mathematical model for adding phosphorus removal agents 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 ... 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 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 in the effluent; S represents the cross-sectional area of ​​the reactor 1 (if the reactor is a cylinder, 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 (in %), 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 phosphorus removal agent dosing pump 17 is based on the reaction (stirring) stage 20 and the phosphorus removal agent mathematical model algorithm of the PLC control cabinet 13 as the core. The phosphorus removal 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 phosphorus removal agent dosing pump 17 is adjusted to match the phosphorus removal agent dosing pump flow Q, and then the phosphorus removal agent dosing pump 17 is started to add the phosphorus removal agent to the reactor 1 at the flow Q. After the phosphorus removal agent dosing pump 17 has added the phosphorus removal agent for T time, the phosphorus removal agent dosing pump 17 is turned off, and the phosphate in the mixed liquid in the reactor 1 reacts chemically with the phosphorus removal agent to generate aluminum salt precipitate, and then sludge is discharged in the idle stage 23, thereby achieving the purpose of phosphorus removal.

[0088] Step 7: 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 the nitrifying bacteria continue to consume the residual dissolved oxygen through nitrification, and continuously stir 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 to drop 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. The denitrifying bacteria in the mixed liquid in the reactor 1 use an external carbon source as an electron donor to carry out denitrification under anoxic conditions, 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, 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 finally 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 outlet water, S represents the cross-sectional area of ​​the reactor 1, H represents the liquid level height after the reactor is filled with water, and 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 PLC control cabinet 13 monitors that the dissolved oxygen concentration in the mixed liquid in the reactor 1 is below 0.5 mg / L through the online dissolved oxygen probe 11, 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 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 sewage 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 once, the mixed liquid in the reactor 1, the phosphorus removal agent and the carbon source undergo chemical phosphorus removal and biological denitrification under the condition of sufficient stirring in the agitator 6, and the phosphate and nitrate nitrogen in the sewage are removed. 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 decreasing to a constant level, the PLC control cabinet 13 follows the following control logic:

[0097] When the phosphate probe 10 detects that the phosphate concentration Ps' in the mixed solution decreases to remain constant and Ps'-Pc ≤ 10% Pc, it indicates that step six is ​​completed;

[0098] When the online phosphate probe 10 detects that the phosphate concentration Ps' in the mixed solution decreases to remain constant, if Ps'-Pc>10%Pc, the loop execution mode of step six formulas (1) and (2) is entered until Ps'-Pc≤10%Pc, which indicates 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 solution decreases to remain constant and Ns'-Nc ≤ 5% Nc, it means that 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 remain unchanged, if Ns'-Nc>5%Pc, the cycle execution mode of step seven formulas (1) and (2) is entered until Ns'-Nc≤5%Nc, which indicates that the cycle execution mode ends and step seven execution ends;

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

[0102] Step 10: 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, so that the clarified supernatant is separated 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, 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.

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

[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] Embodiment 2:

[0107] The intelligent dosing control system and use method for nitrogen and phosphorus removal 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 SBR main process. The size of SBR tank is 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 effluent TN is 15mg / L, of which effluent NH4 + -N is 5mg / L. Due to the characteristics of chemical wastewater, the actual concentration of organic nitrogen in the effluent is lower than 0.5mg / L. The effluent nitrate nitrogen concentration should not be higher than 9.5mg / L. The effluent nitrate nitrogen Nc concentration is set to 8mg / L. According to the design of the sewage treatment system, the effluent TP is 0.5mg / L. Due to the characteristics of chemical wastewater, the actual concentration of organic phosphorus in the effluent is lower than 0.1mg / L. The effluent phosphate concentration should not be higher than 0.4mg / L. The effluent phosphate Pc concentration is set to 0.25mg / L.

[0112] In the process of nitrogen and phosphorus removal in sewage treatment, the added carbon source is sodium acetate, and the COD equivalent is 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 1.12g / cm 3 .

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

[0114] Step 1: Start entering the water inlet stage (stirring) 18, the water inlet pump 2 injects slaughter wastewater into the reactor 1, and starts the stirrer 6 for continuous stirring, so that the slaughter 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 certain 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 through the online nitrate nitrogen probe 9 that the nitrate nitrogen concentration in the mixed liquid in the reactor 1 has dropped 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 duct, the air enters the mixed liquid through the aeration disk 5, the mixed liquid in the reactor 1 changes from an anaerobic 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: Start to enter the reaction (stirring) stage 20, turn off the blower 3, and continue to operate the stirrer 6 to keep the mixed liquid in the reactor 1 in a mixed state. The PLC control cabinet 13 monitors the concentrations of dissolved oxygen, nitrate nitrogen and phosphate 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 algorithm 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 adding phosphorus removal agents 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, and 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, and the length and width of the SBR tank in 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 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%, and 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 phosphorus removal agent dosing pump 17 is based on the reaction (stirring) stage 20 and the phosphorus removal agent mathematical model algorithm of the PLC control cabinet 13 as the core. The phosphorus removal 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 phosphorus removal agent dosing pump 17 is adjusted to match the phosphorus removal agent dosing pump flow Q, and then the phosphorus removal agent dosing pump 17 is started to add the phosphorus removal agent to the reactor 1 at the flow Q. After the phosphorus removal agent dosing pump 17 has added the phosphorus removal agent for T time, the phosphorus removal agent dosing pump 17 is turned off, and the phosphate in the mixed liquid in the reactor 1 reacts chemically with the phosphorus removal agent to generate aluminum salt precipitate, and then sludge is discharged in the idle stage 23, thereby achieving the purpose of phosphorus removal.

[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, and continuously stir 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 to drop 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. The denitrifying bacteria in the mixed liquid in the reactor 1 use an external carbon source as an electron donor to carry out denitrification under anoxic conditions, 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:

[0125]

[0126]

[0127] In formula (3), V represents the volume of carbon source solution, 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 finally 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 PLC control cabinet 13 monitors that the dissolved oxygen concentration in the mixed liquid in the reactor 1 is below 0.5 mg / L through the online dissolved oxygen probe 11, 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 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 sewage 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 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;

[0133] Step 8: After the phosphorus removal agent and carbon source are added once, the mixed liquid in the reactor 1, the phosphorus removal agent and the carbon source undergo chemical phosphorus removal and biological denitrification under the condition of sufficient stirring in the agitator 6, and the phosphate and nitrate nitrogen in the sewage are removed. 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 decreasing to a constant level, the PLC control cabinet 13 follows the following control logic:

[0134] When the phosphate probe 10 detects that the phosphate concentration Ps' in the mixed solution decreases to remain constant and Ps'-Pc ≤ 10% Pc, it indicates that step six is ​​completed;

[0135] When the online phosphate probe 10 detects that the phosphate concentration Ps' in the mixed solution decreases to remain constant, if Ps'-Pc>10%Pc, the loop execution mode of step six formulas (1) and (2) is entered until Ps'-Pc≤10%Pc, which indicates 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 solution decreases to remain constant and Ns'-Nc ≤ 5% Nc, it means that 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 remain unchanged, if Ns'-Nc>5%Pc, the cycle execution mode of step seven formulas (1) and (2) is entered until Ns'-Nc≤5%Nc, which indicates that the cycle execution mode ends and step seven execution ends;

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

[0139] Step nine: 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, so that the clarified supernatant is separated 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 discharge pump 8 according to the sludge age and sludge concentration requirements to discharge a certain amount of excess sludge, and closing the sludge discharge pump 8 after the sludge discharge is completed, waiting for the start of the next cycle.

[0142] Step 12: 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.

[0143] This project uses the intelligent dosing control system for nitrogen 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 of the effluent, from the 1st day to the 30th day, the traditional automatic control was used, and the maximum total nitrogen concentration of 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 of the effluent fluctuated greatly, and at the same time, it showed a positive correlation with the total nitrogen in the inlet. The maximum total phosphorus of 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 of the effluent fluctuated slightly, which was far below the target control value, indicating that the phosphorus removal agent was excessively added, resulting in a waste of the agent. After the intelligent dosing control system was used on the 31st day, the fluctuation range of the effluent water quality was small, among which the maximum total nitrogen of the effluent was 8.63 mg / L, the minimum was 7.82 mg / L, and the average was 8.23 ​​mg / L, and the maximum total phosphorus of the effluent was 0.29 mg / L, the minimum was 0.20 mg / L, and the average was 0.25 mg / L. The total nitrogen and total phosphorus concentrations in the effluent basically fluctuate around the target control value, realizing intelligent dosing on demand. From the perspective of operating costs, after adopting the intelligent dosing control system for nitrogen and phosphorus removal, the dosage of carbon source and phosphorus removal agent is adjusted on demand, and the cost of agents is significantly reduced by 35% compared with traditional automatic control.

[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 as above in the form of a preferred embodiment, 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. An intelligent dosing control system for nitrogen and phosphorus removal in sewage treatment process, characterized in that: Including SBR reactor module and intelligent dosing control module; The SBR reactor module includes a reactor, a water inlet pump, a blower, a gas flow meter, an aeration plate, an agitator, a water outlet solenoid valve, and a mud pump; The water inlet pump is connected to the reactor through a water inlet pipe; 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 agitator is located inside the reactor; The water outlet solenoid valve is located outside the reactor and connected to the reactor via a water outlet pipe; The sludge pump is located outside the reactor and connected to the reactor through a sludge pipeline; The intelligent dosing control module includes an online nitrate nitrogen probe, an online phosphate probe, an online dissolved oxygen probe, an online ammonia nitrogen probe, a PLC control cabinet, a carbon source electromagnetic flowmeter, a carbon source variable frequency dosing pump, a dephosphorization agent electromagnetic flowmeter, and a dephosphorization agent variable frequency dosing pump; 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; 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, and the PLC control cabinet is located outside the reactor; The carbon source electromagnetic flowmeter, the carbon source variable frequency dosing pump, the dephosphorus agent electromagnetic flowmeter, and the dephosphorus 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 dephosphorus agent electromagnetic flowmeter is connected to the dephosphorus agent variable frequency dosing pump and the reactor respectively through a dosing pipeline, and the flow rates measured by the carbon source electromagnetic flowmeter and the dephosphorus agent electromagnetic flowmeter are transmitted to the PLC control cabinet through a signal line; The electrical signals of the carbon source variable frequency dosing pump and the dephosphorization agent variable frequency dosing pump are connected to the PLC control cabinet through signal lines, and the PLC control cabinet controls the start and stop of the carbon source variable frequency dosing pump and the dephosphorization agent variable frequency dosing pump.

2. The intelligent dosing control system for nitrogen removal and phosphorus removal according to claim 1 is characterized in that: The PLC control cabinet calculates the online data of phosphate and nitrate nitrogen through the mathematical model algorithm of the carbon source and the phosphorus removal agent to obtain the dosage and addition time of the agent.

3. The intelligent dosing control system for nitrogen removal and phosphorus removal according to claim 1 is characterized in that: The PLC control cabinet controls the start and stop of the carbon source variable frequency dosing pump and the dephosphorization agent variable frequency dosing pump according to the agent dosage and dosing time obtained by the mathematical model algorithm.

4. The intelligent dosing control system for nitrogen removal and phosphorus removal according to claim 2 or 3 is characterized in that: The specific calculation method of the mathematical model for adding phosphorus removal agents 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 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, and when Ps≤0.15, β takes a value of 20; Ps represents the phosphate concentration finally monitored by the online phosphate probe before adding the dephosphorization agent in the reaction (stirring) 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 dephosphorization agent, e represents the effective content of the effective aluminum in the dephosphorization agent in the dephosphorization agent solution, and ρ represents the density of the dephosphorization 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.

5. The intelligent dosing control system for nitrogen removal and phosphorus removal according to claim 2 or 3 is characterized in that: 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°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 finally 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 outlet water, S represents the cross-sectional area of ​​the reactor, H represents the liquid level height after the reactor is filled with water, and 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.

6. A method for treating sewage using the intelligent control system for nitrogen and phosphorus removal according to any one of claims 1 to 5, characterized in that: include: The core of the SBR sewage treatment process is the reaction tank. The operation process in chronological order is five operation stages: stirring water inlet, aeration stirring reaction, stirring reaction, sedimentation, water outlet, and idle. From the beginning of water inlet to the end of idleness, it constitutes an operation cycle. Entering the stirring water inlet stage, the water inlet pump injects sewage into the reactor, and the agitator is started for continuous stirring. When the reactor is filled with water, the water inlet is stopped, and the liquid level height is H at this time; during the stirring water inlet stage, the concentration of nitrate nitrogen remaining in the mixed liquid in the reactor will gradually decrease as the stirring water inlet stage continues, until the PLC control cabinet monitors through the online nitrate nitrogen probe that the concentration of nitrate nitrogen in the mixed liquid in the reactor drops to 0 mg / L, or remains unchanged, and then the stirring water inlet stage is ended; Entering the aeration and stirring reaction stage, the blower is started, and air is injected into the aeration plate in the reactor through the air pipe. The air enters the mixed liquid through the aeration plate. The ammonia nitrogen concentration in the mixed liquid in the reactor gradually decreases as the aeration and stirring reaction 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 aeration and stirring reaction stage is ended; Entering the stirring reaction stage, the blower is turned off, and the stirrer is continued to operate to keep the mixed liquid in the reactor in a mixed 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; Among them, in the stirring reaction stage, a mathematical model algorithm is established to calculate the dosage and addition time of the carbon source and the phosphorus removal agent; The specific calculation method of the mathematical model for adding phosphorus removal agents 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 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, and when Ps≤0.15, β takes a value of 20; Ps represents the phosphate concentration finally monitored by the online phosphate probe before adding the dephosphorization agent in the reaction (stirring) 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 dephosphorization agent, e represents the effective content of the effective aluminum in the dephosphorization agent in the dephosphorization agent solution, and ρ represents the density of the dephosphorization 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 start and stop logic of the phosphorus removal agent dosing pump is based on the stirring reaction stage and the phosphorus removal agent mathematical model algorithm of the PLC control cabinet as the core. The phosphorus removal agent dosage V and the addition time T are obtained according to the phosphate concentration in the mixed solution monitored by the online phosphate probe, and then the phosphorus removal agent dosing pump frequency is adjusted to match the phosphorus removal agent dosing pump flow Q, and then the phosphorus removal agent dosing pump is started to add the phosphorus removal agent to the reactor at the flow Q. After the phosphorus removal agent dosing pump has added the phosphorus removal agent for the T time, the phosphorus removal agent dosing pump is turned off, and the phosphate in the mixed solution in the reactor reacts chemically with the phosphorus removal agent to generate aluminum salt precipitate, and then sludge is discharged during the idle stage, thereby achieving the purpose of phosphorus removal; 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°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 finally 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 outlet water, S represents the cross-sectional area of ​​the reactor, H represents the liquid level height after the reactor is filled with water, and 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 start and stop logic of the carbon source dosing pump is based on the stirring reaction stage and the dissolved oxygen concentration in the mixed liquid in the reactor at this stage, and the carbon source mathematical model algorithm of the PLC control cabinet is the core. 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. 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 other carbon source dosing pump is started to add carbon source to the reactor at the flow rate Q. After the carbon source dosing pump ends the addition time T, the carbon source dosing pump is turned off; Before adding the phosphorus removal agent or carbon source, the PLC control cabinet follows the following control logic: When the SBR sewage treatment process is in the reaction (stirring) stage, formulas (1) and (2) are executed; When the SBR sewage 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, formulas (3) and (4) are executed; When the phosphorus removal agent and carbon source are added once, the mixed liquid in the reactor, the phosphorus removal agent and the carbon source undergo chemical phosphorus removal and biological denitrification under the condition of sufficient stirring in the agitator, and the phosphate and nitrate nitrogen in the sewage are removed. 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: When the online phosphate probe detects that the phosphate concentration Ps' in the mixed solution decreases to remain constant and Ps'-Pc ≤ 10% Pc, it indicates that the addition of the dephosphorization agent is completed; 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 cycle execution mode of formulas (1) and (2) is entered until Ps'-Pc≤10%Pc, indicating that the cycle execution mode ends and the addition of the dephosphorization agent ends; When the online nitrate nitrogen probe detects that the nitrate nitrogen concentration Ns' in the mixed solution decreases to remain constant and Ns'-Nc ≤ 5% Nc, it indicates that the carbon source addition is completed; When the online nitrate nitrogen probe detects that the nitrate nitrogen concentration Ns' in the mixed solution decreases to remain constant, if Ns'-Nc>5%Pc, the cycle execution mode of formulas (1) and (2) is entered until Ns'-Nc≤5%Nc, which means that the cycle execution mode ends and the carbon source addition execution ends; When Ps'-Pc≤10%Pc and Ns'-Nc≤5%Nc, the agitator is stopped to terminate the reaction (stirring) stage; Entering the sedimentation stage, the agitator is turned off, and the activated sludge in the mixed liquid in the reactor naturally settles to the bottom of the reactor under the action of gravity, so that the clarified supernatant is separated from the activated sludge. After being kept in a static state, the sedimentation stage ends; Entering the water discharge stage, opening the water discharge solenoid valve to discharge the supernatant in the reactor, and closing the water discharge solenoid valve after the liquid level in the reactor drops to h, stopping the water discharge, and ending the water discharge stage; Entering the idle stage, starting the sludge discharge pump to discharge a certain amount of excess sludge according to the sludge age and sludge concentration requirements, and closing the sludge discharge pump after the sludge discharge is completed, waiting for the start of the next cycle; An operation cycle is formed from the start of water intake to the end of idleness, and then the cycle is repeated.

7. Application of the intelligent control system for nitrogen removal and phosphorus removal according to any one of claims 1 to 5 in sewage treatment.

8. A method for treating sewage, characterized in that: Utilize the intelligent control system for nitrogen removal and phosphorus removal as described in claim 1.

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