Sewage treatment device and control method thereof

Abstract

The invention relates to the technical field of sewage treatment, in particular to a sewage treatment device and a control method thereof. The problem that the discharged water cannot be discharged to meet the discharge standard when the temperature of the sewage and the ammonia nitrogen load change is at least solved. The sewage treatment device comprises a first anoxic tank, a first aerobic tank, an aeration device, a water body detection device, an air flow detection device and a controller. The controller is configured to obtain water body parameters and air flow. Calculating the aeration quantity according to the water body parameters. And controlling the aeration device according to the aeration rate and the airflow rate. Thus, the aeration rate is linked with real-time process requirements (temperature and ammonia nitrogen load), and the first aerobic tank can be in a dissolved oxygen environment suitable for nitrifying flora under different water inlet conditions, so that the stability of ammonia nitrogen removal efficiency is improved, and the risk that the ammonia nitrogen concentration of effluent exceeds the standard is reduced.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a wastewater treatment device and its control method. Background Technology

[0002] With the development of technology, the effluent quality of most sewage treatment plants in China has met the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002). However, in many sewage treatment plants in sensitive areas that are prone to pollution, in addition to meeting the Class A standard, important effluent indicators such as COD, ammonia nitrogen, total nitrogen (TN), and total phosphorus (TP) should meet or exceed the Class IV effluent standard of the "Environmental Quality Standard for Surface Water" (GB3838-2002).

[0003] To meet higher effluent standards, a pure biofilm biological wastewater treatment process is used. This process is characterized by its small footprint and high removal capacity. Based on the growth pattern of microorganisms on the suspended packing material used in the moving bed pure biofilm process, it is mainly divided into two types of biological treatment tanks: the "sludge-film composite process," where activated sludge and microorganisms grow simultaneously on the suspended packing material; and the "pure membrane process," where only the biofilm grows on the suspended packing material.

[0004] The "pure membrane process" is affected by seasonal temperature changes in the reaction mixture temperature, as well as by the ammonia nitrogen load in the wastewater. When the wastewater temperature and ammonia nitrogen load change, the discharged water cannot meet the discharge standards. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a wastewater treatment device and its control method. This addresses the issue that, at least when wastewater temperature or ammonia nitrogen load changes, the discharged water cannot meet emission standards.

[0006] Firstly, a wastewater treatment device is provided. The wastewater treatment device includes: a first anoxic tank, a first aerobic tank, an aeration device, a water quality monitoring device, an air flow rate monitoring device, and a controller. The first aerobic tank is located downstream of and connected to the first anoxic tank along the water flow direction. The aeration device is connected to the first aerobic tank and is used to supply air into the first aerobic tank. The water quality monitoring device is used to detect water parameters, including the temperature of the first aerobic tank, the ammonia nitrogen concentration entering the first aerobic tank, and the ammonia nitrogen concentration leaving the first aerobic tank. The air flow rate monitoring device is used to detect the air flow rate of the aeration device. The aeration device, the water quality monitoring device, and the air flow rate monitoring device are communicatively connected to the controller. The controller is configured to: acquire water parameters and air flow rate; calculate the aeration rate based on the water parameters; and control the aeration device based on the aeration rate and air flow rate.

[0007] Based on these parameters, the controller calculates the aeration rate that meets the current nitrification requirements and is suitable for the temperature conditions. Then, it compares this calculated aeration requirement with the measured airflow rate to perform closed-loop control of the aeration device's operating status (such as blower frequency and valve opening). In this way, by linking the aeration rate with real-time process requirements (temperature, ammonia nitrogen load), the first aerobic tank can be kept in a dissolved oxygen environment suitable for nitrifying bacteria under different influent conditions, thereby improving the stability of ammonia nitrogen removal efficiency and reducing the risk of excessive ammonia nitrogen concentration in the effluent.

[0008] In one possible implementation, the controller is configured to calculate the aeration rate based on water parameters, including: calculating the dissolved oxygen demand and the oxygen demand of the first aerobic tank based on the water parameters; calculating the oxygenation efficiency based on the water parameters and the dissolved oxygen demand; and calculating the aeration rate based on the oxygenation efficiency and the oxygen demand of the first aerobic tank.

[0009] In one possible implementation, the controller is configured to control the aeration device based on the aeration volume and air flow rate, including: determining whether the aeration volume is less than the air flow rate; when the aeration volume is less than the air flow rate, controlling the aeration device to supply air; and when the aeration volume is greater than or equal to the air flow rate, controlling the aeration device to stop supplying air.

[0010] In one possible implementation, the wastewater treatment apparatus further includes a second anoxic tank and a carbon source replenishment device. The second anoxic tank is located downstream of and connected to the first aerobic tank. The carbon source replenishment device is connected to the second anoxic tank and is used to replenish carbon sources into the second anoxic tank.

[0011] In one possible implementation, the water parameters also include the nitrate nitrogen concentration entering the first anoxic tank and the nitrate nitrogen concentration exiting the first anoxic tank. The wastewater treatment device also includes a carbon source flow detection device for detecting the amount of carbon source supplementation by the carbon source supplementation device. The controller is communicatively connected to the carbon source supplementation device and also communicatively connected to the carbon source flow detection device. After acquiring the water parameters and air flow rate, the controller is further configured to acquire the amount of carbon source supplementation. Based on the water parameters, the carbon source demand for the second anoxic tank is calculated. The carbon source supplementation device is controlled based on the carbon source demand and the amount of carbon source supplementation.

[0012] In one possible implementation, the wastewater treatment apparatus further includes a second aerobic tank, which is located downstream of and connected to the second anoxic tank. An aeration device is also connected to the second anoxic tank and is used to supply oxygen to it.

[0013] In one possible implementation, the wastewater treatment apparatus further includes a flocculation tank, a flocculant dosing device, and a coagulant aid dosing device. The flocculant dosing device is connected to the flocculation tank and also to a second aerobic tank, and is used to add flocculant to both the flocculation tank and the second aerobic tank. The coagulant aid dosing device is also connected to the flocculation tank and also to the second aerobic tank, and is used to add coagulant aid to both the flocculation tank and the second aerobic tank.

[0014] Secondly, a control method for a wastewater treatment device is provided, which is the wastewater treatment device provided in any embodiment of the first aspect. The wastewater treatment device includes an aeration device. The control method includes: acquiring water parameters and air flow rate; calculating the aeration rate based on the water parameters; and controlling the aeration device based on the aeration rate and air flow rate.

[0015] In one possible implementation, calculating the aeration rate based on water parameters includes: calculating the dissolved oxygen demand and the oxygen demand of the first aerobic tank based on the water parameters; calculating the oxygenation efficiency based on the water parameters and dissolved oxygen demand; and calculating the aeration rate based on the oxygenation efficiency and the oxygen demand of the first aerobic tank. And / or, controlling the aeration device of the wastewater treatment plant based on the aeration rate and air flow rate includes: determining whether the aeration rate is less than the air flow rate; controlling the aeration device to supply air when the aeration rate is less than the air flow rate; and controlling the aeration device to stop supplying air when the aeration rate is greater than or equal to the air flow rate.

[0016] In one possible implementation, the wastewater treatment apparatus further includes: a second anoxic tank located downstream of and connected to the first aerobic tank; a carbon source replenishment device connected to the second anoxic tank and used to replenish carbon source to the second anoxic tank; and a carbon source flow detection device for detecting the amount of carbon source replenished by the carbon source replenishment device. After acquiring the water parameters and air flow rate, the control method further includes: acquiring the amount of carbon source replenishment; calculating the carbon source demand of the second anoxic tank based on the water parameters; and controlling the carbon source replenishment device based on the carbon source demand and the amount of carbon source replenishment.

[0017] It should be noted that the technical effects of any implementation method in the second aspect can be found in the technical effects of the corresponding implementation method in the first aspect, and will not be repeated here. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a wastewater treatment device provided in an embodiment of this application; Figure 2 A schematic diagram of a controller connection is provided for an embodiment of this application; Figure 3 This is a schematic diagram of a control method provided in an embodiment of this application; Figure 4 A schematic diagram of another control method provided in the embodiments of this application; Figure 5 This is a schematic diagram of another control method provided in an embodiment of this application; Figure 6 A schematic diagram of another control method is provided for the embodiments of this application.

[0021] Explanation of reference numerals in the attached figures: 1. First anoxic tank; 2. First aerobic tank; 3. Aeration device; 41. Water quality monitoring device; 411. Temperature sensor; 412. First ammonia nitrogen concentration analyzer; 413. Second ammonia nitrogen concentration analyzer; 414. Flow sensor; 415. First COD analyzer; 416. Second COD analyzer; 417. First nitrate nitrogen detector; 418. Second nitrate nitrogen detector; 42. Air flow rate detection device; 43. Carbon source flow rate detection device; 5. Controller; 6. Second anoxic tank; 7. Carbon source replenishment device; 8. Second aerobic tank; 9. Flocculation tank; 91. Flocculant dosing device; 92. Coagulant dosing device; 93. Air flotation tank; 94. Air flotation device. Detailed Implementation

[0022] To better understand the above-mentioned objectives, features, and advantages of this application, the solution of this application will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of this application, but this application may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of this application, and not all embodiments.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0025] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects are in an "or" relationship.

[0028] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0029] Before describing the embodiments of this application, the background of this application will be described in detail first.

[0030] According to the Class IV effluent standards of the "Surface Water Environmental Quality Standard" (GB3838-2002), the chemical oxygen demand (COD) should be ≤30mg / l, the five-day biochemical oxygen demand (BOD5) should be ≤6mg / l, the ammonia nitrogen (NH3-N) should be ≤1.5mg / l, the total nitrogen (TN) should be ≤1.0-1.5mg / l, and the total phosphorus (TP) should be ≤0.3mg / l. The effluent quality must also be consistently up to standard.

[0031] In biochemical processes, the moving bed pure biofilm biochemical wastewater treatment process is characterized by its small footprint and high removal load. Based on the growth mode of the suspended packing material used by microorganisms in its moving bed pure biofilm process, this process is mainly divided into the "sludge-film composite process," where activated sludge and microorganisms grow simultaneously on the suspended packing material, and the "pure membrane process," where only the biofilm grows on the suspended packing material.

[0032] In the "mud-film composite process" system, there is a problem that the suspended packing does not fully play its role as a biofilm carrier. This is because there is competition between the microorganisms in the biofilm and those present in the activated sludge for pollutants and dissolved oxygen (DO). The presence of microorganisms in the activated sludge limits the growth and efficiency of the biofilm. Only under scenarios where the treatment capacity of the activated sludge microorganisms is significantly impacted, such as low temperature, high salinity, or strong pollution load shocks, will the biofilm on the suspended packing, due to its strong shock resistance, fully exert its strong treatment capacity.

[0033] Therefore, this application uses a pure biofilm processing technology.

[0034] The present application will now be described in detail. Before describing the embodiments of the present application, the logic behind the technical problem arising from the present application will be explained first.

[0035] Wastewater treatment devices using pure biofilm biochemical processes face the risk of unstable biochemical reaction efficiency and effluent quality exceeding standards due to factors such as seasonal fluctuations in influent temperature and changes in ammonia nitrogen load, resulting in substandard discharged water.

[0036] The embodiments of this application are described below.

[0037] See Figure 1 and Figure 2 As shown. This application provides a wastewater treatment device. The wastewater treatment device includes: a first anoxic tank 1, a first aerobic tank 2, an aeration device 3, a water body detection device 41, an air flow detection device 42, and a controller 5.

[0038] The first anoxic tank 1 is part of the biological unit of the wastewater treatment plant. In this tank, the dissolved oxygen concentration is controlled at a certain level (typically below 0.5 mg / L) to create an anaerobic environment conducive to the growth of denitrifying bacteria. These bacteria utilize organic matter in the water as a carbon source to reduce nitrate nitrogen returned from the first aerobic tank 2 to nitrogen gas, thereby achieving the removal of total nitrogen.

[0039] For example, the first anoxic pool 1 can be constructed as a rectangular or circular pool with a specific length-to-width ratio. Its materials typically include, but are not limited to: reinforced concrete, fiberglass, corrosion-resistant carbon steel sheets, or high-performance plastics.

[0040] In one possible implementation, the tank is typically equipped with a stirring device. Specifically, the stirring device includes, but is not limited to, a submersible mixer or a hydraulic propeller, to prevent the sedimentation of activated sludge or suspended packing material and to promote thorough mixing of wastewater and microorganisms.

[0041] For example, the first anoxic pool 1 is connected to the downstream first aerobic pool 2 via a pipe, channel, or weir. The connection method can be bottom connection, top overflow, or side opening.

[0042] It should be noted that the first anoxic tank 1 and the first aerobic tank 2 are also connected by internal water passages, guide walls, or external return pipes. In this case, the water flow direction is from the first aerobic tank 2 to the first anoxic tank 1.

[0043] The first aerobic tank 2 is part of the biological unit of the wastewater treatment plant. In this tank, oxygen is introduced into the mixed liquor through an aeration device 3 to maintain a high dissolved oxygen concentration (typically 2-4 mg / L), providing conditions for the growth and metabolism of aerobic microorganisms (mainly nitrifying bacteria). Its main function is to oxidize ammonia nitrogen in the influent into nitrate nitrogen and further degrade organic pollutants.

[0044] For example, the first aerobic tank 2 is typically constructed as a plug-flow or fully mixed tank. The tank is filled with suspended biological packing materials, such as MBBR (moving bed biofilm reactor) packing materials, which provide surface area for microbial attachment and growth.

[0045] For example, the materials of suspended biological fillers include, but are not limited to, high-density polyethylene, polypropylene, or plastics with modified hydrophilic coatings.

[0046] Aeration device 3 is used to forcibly deliver oxygen or air into the mixed liquor. Its function is to increase the dissolved oxygen content in the water to meet the respiratory needs of aerobic microorganisms.

[0047] For example, the aeration device 3 includes a gas source, a gas delivery pipeline, and a gas release component. Specifically, the gas source can be a Roots blower, a centrifugal blower, or an air compressor.

[0048] Gas transmission pipelines include main pipes, branch pipes, and valves, and the materials include, but are not limited to: UPVC, stainless steel, or galvanized steel pipes.

[0049] Gas release components (i.e., aerators) can be disc microporous aerators, tubular aerators, perforated aeration pipes, or surface aerators. Aerators are typically fixed to the bottom of the tank by supports or counterweights and connected to air ducts via flanges, threads, or special fittings.

[0050] The gas release component is located at the bottom of the pool, and the aeration method can be microporous aeration, swirling aeration, or jet aeration.

[0051] The water body detection device 41 is an analytical instrument and / or sensor used for online or intermittent measurement and collection of one or more physical and chemical parameters in water.

[0052] For example, the water body detection device 41 includes a temperature sensor 411 for detecting temperature, an ammonia nitrogen analyzer or an ammonia nitrogen concentration sensor for detecting ammonia nitrogen concentration.

[0053] The installation methods of temperature sensor 411 include, but are not limited to: immersion installation in the first aerobic pool 2 or in the bypass sampling tube, and its probe material can be platinum resistance or thermocouple.

[0054] Ammonia nitrogen analyzers can sample water directly from the tank or by using a peristaltic pump to draw the sample into the analyzer's measuring cell. Analytical principles include ion-selective electrode method, colorimetry, or ultraviolet absorption method.

[0055] For example, the first ammonia nitrogen concentration analyzer 412 for detecting the ammonia nitrogen concentration entering the first aerobic tank 2 can be installed at the outlet of the first anoxic tank 1 or the inlet of the first aerobic tank 2; it can also be installed at the inlet of the first anoxic tank 1. It should be noted that, upstream of the first aerobic tank 2, when the ammonia nitrogen concentration does not change, the first ammonia nitrogen concentration analyzer 412 can be installed in any section upstream of the first aerobic tank 2.

[0056] The second ammonia nitrogen concentration analyzer 413, used to detect the ammonia nitrogen concentration flowing out of the first aerobic tank 2, is installed at the end of the first aerobic tank 2 or at the outlet. Similarly, downstream of the first aerobic tank 2, when the ammonia nitrogen concentration does not change, the second ammonia nitrogen concentration analyzer 413 can be installed in any section downstream of the first aerobic tank 2.

[0057] In this application, the water body detection device 41 also includes a flow detector or flow sensor 414 for detecting the water flow rate. Taking the flow sensor 414 as an example, the flow sensor 414 is located upstream of the first aerobic tank 2, and its location can be referred to the location of the ammonia nitrogen concentration analyzer upstream of the first aerobic tank 2.

[0058] The water quality monitoring device 41 further includes: a first COD analyzer 415 and a second COD analyzer 416. The first COD analyzer 415 is used to detect the chemical oxygen demand (COD) of the water entering the first anoxic tank 1. The second COD analyzer 416 is used to detect the COD of the water flowing out of the first aerobic tank 2. The first COD analyzer 415 can be installed in any section upstream of the first anoxic tank 1. The second COD analyzer 416 is installed at the end of the first aerobic tank 2 or at its outlet. Chemical oxygen demand (COD) refers to the total amount of pollutants in the water that can be oxidized by chemical oxidants.

[0059] The air flow detection device 42 is used to measure the total volume of gas in the pipes or channels of the aeration device 3. The air flow detection device 42 can convert the detected cumulative flow signal into a standard electrical signal output.

[0060] For example, the gas flow detection device 42 may be a vortex flow meter, a thermal gas mass flow meter, an orifice plate flow meter, or a turbine flow meter.

[0061] The controller 5 is an automated device that can receive input signals, process them according to preset logic or algorithms, and output control commands to operate the actuators.

[0062] For example, the controller 5 can be a programmable logic controller 5, a distributed control system, or an industrial computer. Its hardware includes a central processing unit, input / output modules, a communication module, and a power supply module. The controller 5 is connected to the aeration device 3, the water body detection device 41, the air flow detection device 42, etc., via wired or wireless communication. The communication protocols include, but are not limited to, Modbus, Profibus, and Ethernet TCP / IP.

[0063] In one possible application scenario, when faced with drastic temperature changes or ammonia nitrogen load shocks, the inability to dynamically adjust the oxygen supply can lead to two situations: insufficient oxygen supply, incomplete nitrification, and excessive ammonia nitrogen in the effluent; or excessive aeration, resulting in energy waste and potentially inhibiting denitrification or causing excessive shedding of the biofilm from the packing material due to excessive dissolved oxygen.

[0064] Temperature directly affects the metabolic rate of microorganisms and the saturated solubility of oxygen, while the difference in ammonia nitrogen concentration directly reflects the actual nitrification load of the system.

[0065] In this application, controller 5 is configured to: acquire water parameters and air flow rate; calculate the aeration rate based on the water parameters; and control the aeration device 3 based on the aeration rate and air flow rate.

[0066] Based on these parameters, controller 5 calculates the aeration rate that meets the current nitrification requirements and is suitable for the temperature conditions. Then, it compares the calculated aeration requirement with the measured air flow rate to perform closed-loop control of the operating status of aeration device 3 (such as blower frequency and valve opening).

[0067] In this way, by linking the aeration rate with real-time process requirements (temperature, ammonia nitrogen load), the first aerobic tank 2 can be kept in a dissolved oxygen environment suitable for nitrifying bacteria under different influent conditions, thereby improving the stability of ammonia nitrogen removal efficiency and reducing the risk of excessive ammonia nitrogen concentration in the effluent.

[0068] Simultaneously, on-demand oxygen supply is achieved, reducing energy waste caused by excessive operation of aeration device 3. When the influent ammonia nitrogen concentration increases (shock load), the system can sense this and increase the aeration rate through calculation, providing sufficient oxygen for nitrifying bacteria to cope with the high load, thereby improving the process system's buffering and adaptability to water quality fluctuations. Precise dissolved oxygen control also helps maintain the biofilm on the suspended packing in a good metabolic state, preventing a decrease in biofilm activity or thickening of the anaerobic layer due to long-term hypoxia, and also preventing excessive shearing and shedding of the biofilm due to long-term over-aeration, which is conducive to maintaining biomass stability.

[0069] In one possible implementation, the controller 5 is configured to calculate the aeration rate based on water parameters, including: calculating the dissolved oxygen demand and chemical oxygen demand (COD) based on the water parameters; calculating the oxygenation efficiency based on the water parameters and dissolved oxygen demand; and calculating the aeration rate based on the oxygenation efficiency and COD.

[0070] Specifically, based on the water parameters, the dissolved oxygen demand and chemical oxygen demand (COD) are calculated. These water parameters include: the ammonia nitrogen concentration entering the first aerobic tank 2, the ammonia nitrogen concentration exiting the first aerobic tank 2, the temperature of the first aerobic tank 2, the instantaneous influent COD value detected by the first COD analyzer 415, the instantaneous effluent COD value detected by the second COD analyzer 416, and the water flow rate. It should be noted that these water parameters are specific numerical values.

[0071] Calculate dissolved oxygen demand based on water parameters. The formula is as follows:

[0072]

[0073]

[0074] This refers to the dissolved oxygen requirement.

[0075] The nitrification constant for a moving bed biofilm process is given when there is no primary sedimentation tank but a pre-denitrification anoxic tank. =0.47, when there is both a primary sedimentation tank and a pre-denitrification anoxic tank. =0.53.

[0076] The temperature of the reaction mixture in the first aerobic tank is the temperature of the first aerobic tank, expressed in °C.

[0077] The reaction order of the nitrification rate of the moving bed biofilm is taken as 0.7.

[0078] The ammonia nitrogen concentration entering the first aerobic tank, in g / m³. 3 .

[0079] The ammonia nitrogen concentration in the water flowing out of the first aerobic tank, in g / m³. 3 .

[0080] The influent flow rate is m. 3 / d.

[0081] The total effective surface area of ​​the suspended packing is given in m. 2 Its value = volume of added suspended packing material × effective specific surface area. For example, if the effective specific surface area of ​​the suspended packing material is 500 m², then... 2 / m 3 .

[0082] R n For pure membrane nitration rate, gNH4 + -N / (m) 2 / d).

[0083] Calculate the chemical oxygen demand based on water parameters. The formula is as follows:

[0084] The chemical oxygen demand (COD) of the first aerobic tank, m 3 / h.

[0085] This represents the instantaneous COD value of the influent collected online.

[0086] This refers to the instantaneous COD value of the effluent collected online.

[0087] For COD oxidation oxygen demand, take =(BOD / COD)=0.7.

[0088] The oxygen equivalent for the ammonia nitrogen nitrification reaction is taken as 4.57.

[0089] The oxygen equivalent produced by denitrification in the pre-anoxic tank is 2.86.

[0090] C represents the aeration safety system, with a value of 1.4.

[0091] It should be noted that during the first run, The value is set as a fixed value, and then the collected value is the ammonia nitrogen concentration downstream of the first aerobic tank.

[0092] The formula for calculating oxygenation efficiency based on water parameters and dissolved oxygen demand is as follows:

[0093] This represents the actual oxygenation efficiency of the reaction mixture.

[0094] =0.8~0.85; =0.9~0.97.

[0095] For standard oxygenation efficiency, for stationary aeration devices, It is a constant value.

[0096] The average dissolved oxygen value of clean water at 20°C =9mg / l.

[0097] The formula for calculating the aeration rate based on oxygenation efficiency and chemical oxygen demand is as follows:

[0098] air aeration rate, m 3 / h. It should be noted that the aeration rate mentioned above refers to the air aeration rate.

[0099] This provides a mechanism-based, verifiable calculation method. Instead of using a fixed empirical value, the oxygenation efficiency is calculated as a dynamic variable based on real-time water parameters and process targets (dissolved oxygen demand). This makes the calculation of aeration volume more closely reflect changes in actual operating conditions, improving the system's adaptability and control accuracy.

[0100] In one possible implementation, the controller 5 is configured to control the aeration device 3 based on the aeration volume and air flow rate, including: determining whether the aeration volume is less than the air flow rate; when the aeration volume is less than the air flow rate, controlling the aeration device 3 to supply air; and when the aeration volume is greater than or equal to the air flow rate, controlling the aeration device 3 to stop supplying air.

[0101] Aeration device 3 is a major energy-consuming component in the wastewater treatment plant. Adopting the aforementioned control method, instead of continuous operation, directly reduces its operating time, thereby saving energy. Simultaneously, reducing frequent frequency conversion or valve adjustments helps extend the service life of key moving equipment. Furthermore, it reduces the disruptive impact on the denitrification environment caused by high dissolved oxygen recirculation to the upstream anoxic tank.

[0102] Meanwhile, compared to complex continuous adjustment, the switching control logic is simple, the program is easy to write, the requirements for the controller are low, the system runs stably, and troubleshooting is easy.

[0103] In one possible implementation, the wastewater treatment device further includes a second anoxic tank 6 and a carbon source replenishment device 7. The second anoxic tank 6 is located downstream of and connected to the first aerobic tank 2. Being downstream of the first aerobic tank 2, the second anoxic tank 6 can directly receive effluent that has undergone nitrification, has a high nitrate nitrogen concentration, and whose dissolved oxygen has decreased after consumption, thus creating favorable influent conditions for denitrification.

[0104] The carbon source replenishment device 7 is connected to the second anoxic pool 6 and is used to replenish the carbon source into the second anoxic pool 6.

[0105] For example, the carbon source replenishment device 7 may include a carbon source storage tank, a transfer pump, pipelines, and dosing nozzles. The connection method may be a pipeline connected to the inlet of the second anoxic pool 6 for surface dosing. The carbon source can be liquid or solid. For example, carbon sources include, but are not limited to, methanol and ethanol.

[0106] In scenarios where total nitrogen levels must meet standards (such as reaching Class IV surface water standards), further reduction of total nitrogen content is necessary. The effluent from the first aerobic tank 2, after thorough nitrification, contains a high concentration of nitrate nitrogen. Although some nitrate nitrogen is returned to the first anoxic tank 1 via pipeline, the total nitrogen content of the effluent from the first aerobic tank 2 may still fail to meet standards. Adding a second anoxic tank 6 provides dedicated reaction space for denitrification.

[0107] Meanwhile, after the pure membrane process undergoes biochemical treatment in the first anoxic tank 1, the easily biodegradable carbon source in the wastewater has been consumed, and the denitrification process requires a sufficient carbon source, so it is necessary to supplement the external carbon source.

[0108] Thus, by adding a dedicated post-denitrification unit (second anoxic tank 6), a complete "nitrification-denitrification" biological nitrogen removal chain is constructed, enabling the device to remove total nitrogen to a low level and meet the stringent requirements for total nitrogen in Class IV surface water.

[0109] For example, the second anoxic tank 6 can serve as a backup unit for dealing with high total nitrogen influent or for raising the denitrification standard. When the total nitrogen influent is not high, carbon source addition can be reduced or stopped; when the requirement is higher, carbon source addition can be quickly started to enhance denitrification.

[0110] Adding the carbon source directly to the inlet of the second anoxic tank 6 allows the carbon source to be utilized by denitrifying bacteria in the most direct and efficient way, reducing the loss of carbon source by heterotrophic bacteria at the front end and improving the carbon source utilization efficiency.

[0111] In one possible implementation, the water parameters also include the nitrate nitrogen concentration entering the first anoxic pool 1 and the nitrate nitrogen concentration exiting the first anoxic pool 1.

[0112] Accordingly, the water body detection device 41 includes a first nitrate nitrogen detector 417 and a second nitrate nitrogen detector 418. The first nitrate nitrogen detector 417 is located at the inlet of the second anoxic tank 6, and the second nitrate nitrogen detector 418 is located at the outlet of the second anoxic tank 6. When the nitrate nitrogen concentration does not change or changes only slightly between the water discharged from the second anoxic tank 6 and the final discharge, the second nitrate nitrogen detector 418 can be installed in any section downstream of the second anoxic tank 6.

[0113] The wastewater treatment device also includes a carbon source flow detection device 43, which is used to detect the amount of carbon source replenishment from the carbon source replenishment device 7.

[0114] The controller 5 is communicatively connected to the carbon source replenishment device 7 and the carbon source flow detection device 43. After acquiring water parameters and air flow rate, the controller 5 is further configured to acquire the carbon source replenishment amount. Based on the water parameters, the carbon source requirement of the second anoxic tank 6 is calculated. The carbon source replenishment device 7 is controlled based on the carbon source requirement and the carbon source replenishment amount.

[0115] Based on the water parameters, the formula for calculating the carbon source requirement of the second anoxic pool 6 is as follows.

[0116]

[0117] The carbon source dosage is expressed in l / h.

[0118] and The concentrations of nitrate nitrogen in the influent and effluent of the post-anoxic tank are shown in mg / L. The value is dynamically measured. During the first run, NO3-N... 出 The set value is 0.5 mg / L, followed by the measured value.

[0119] The value of 0.35 means that 1 mg / L of DO consumes the equivalent of 0.35 mg of NO3. --N consumes carbon sources.

[0120] K1 is 1 mg NO3 - The carbon source equivalent coefficient, expressed as COD, required for N denitrification is generally set to K1 = 4-5.

[0121] This refers to the carbon source COD equivalent, such as 2.1g COD / g for ethanol and 1.5g COD / g for methanol.

[0122] In this way, the carbon source dosage is dynamically linked to the actual nitrate nitrogen load, enabling on-demand addition and avoiding the waste or insufficiency that may result from fixed-ratio or experience-based addition, thus reducing carbon source reagent consumption. At the same time, precise control of the carbon source dosage ensures that there is enough carbon source to complete denitrification and meet total nitrogen emission standards, while preventing the risk of increased COD in the effluent due to excessive carbon source.

[0123] Carbon source addition control is also incorporated into the management scope of the same controller 5, forming a synergy with aeration control. This achieves the coordinated optimization of the nitrification and denitrification processes.

[0124] By monitoring the nitrate nitrogen in the influent and effluent of the first anoxic tank 1, it can not only be used for carbon source calculation, but also to evaluate the effect of internal recirculation denitrification.

[0125] For example, the controller 5 is configured to control the carbon source replenishment device 7 according to the carbon source demand and the carbon source replenishment amount, specifically including: determining whether the carbon source demand is less than the carbon source replenishment amount; when the carbon source demand is greater than the carbon source replenishment amount, controlling the carbon source replenishment device 7 to operate; when the carbon source demand is greater than or equal to the carbon source replenishment amount, controlling the carbon source replenishment device 7 to stop operating.

[0126] In one possible implementation, the wastewater treatment apparatus further includes a second aerobic tank 8, which is located downstream of and connected to the second anoxic tank 6. The aeration device 3 is also connected to the second anoxic tank 6 and is used to supply oxygen to the second anoxic tank 6.

[0127] For example, a contact oxidation tank containing a small amount of packing material can be connected after the second anoxic tank 6 as a second aerobic tank 8.

[0128] For example, aeration device 3 can supply air to the second aerobic tank 8 by adding a branch pipe. Alternatively, a zoned aeration system with adjustable aeration intensity can be used.

[0129] In one possible application scenario, to ensure the completeness of the denitrification reaction in the second anoxic tank 6, an excessive amount of carbon source will be added to the second anoxic tank 6.

[0130] Therefore, by setting up a second aerobic tank 8, and aerating the second aerobic tank 8 when excessive carbon source is added to the second anoxic tank 6, the concentration of organic matter in the effluent is further reduced through aerobic contact oxidation, ensuring that COD consistently meets the standards.

[0131] Meanwhile, the second aerobic tank 8 can also remove nitrogen entrained in the water, which is conducive to efficient solid-liquid separation in the subsequent sedimentation tank and reduces suspended solids in the effluent.

[0132] This allows the aeration device 3 to serve both the first aerobic tank 2 and the second aerobic tank 8 simultaneously, thus improving the utilization rate of the aeration system equipment.

[0133] In summary, the multiple alternating processes of "anoxic-aerobic-anoxic-aerobic" enhance the denitrification and carbon removal effects, thereby ensuring that emissions meet standards.

[0134] Biological treatment primarily removes dissolved pollutants, but its removal capacity is limited for colloidal, finely suspended phosphorus, and residual suspended microorganisms in water bodies. To meet the stringent requirements for total phosphorus and suspended solids in the Class IV surface water standard, chemical-assisted phosphorus removal and enhanced solid-liquid separation are necessary.

[0135] In one possible implementation, the wastewater treatment device further includes a flocculation tank 9, a flocculant dosing device 91, and a coagulant aid dosing device 92.

[0136] In addition to setting up an independent flocculation tank 9 and a dosing device, chemical phosphorus removal can be more closely integrated with the biochemical process.

[0137] The flocculant dosing device 91 is connected to the flocculation tank 9 and the second aerobic tank 8. The flocculant dosing device 91 is used to add flocculant to the flocculation tank 9 and the second aerobic tank 8. The coagulant aid dosing device 92 is connected to the flocculation tank 9 and the second aerobic tank 8. The coagulant aid dosing device 92 is used to add coagulant aid to the flocculation tank 9 and the second aerobic tank 8.

[0138] A flocculation tank 9 is installed downstream of the second aerobic tank 8. Flocculants are added to both the second aerobic tank 8 and the flocculation tank 9. The flocculants' metal ions react with dissolved phosphates in the water to form insoluble precipitates (chemical phosphorus removal), while simultaneously destabilizing colloids through charge neutralization. Coagulant aids are added, and through the adsorption and bridging effect of their polymer chains, fine precipitates, colloids, and suspended particles are aggregated into large flocs. These flocs are effectively removed in subsequent sedimentation or filtration units.

[0139] The addition point of flocculant and coagulant aid was moved from the inlet of the single flocculation tank 9 to the end of the biological treatment section—the second aerobic tank 8. This constructed a two-stage chemical enhancement treatment process of "pre-flocculation-main flocculation".

[0140] Adding chemicals to the second aerobic tank 8 allows for preliminary and rapid mixing of the chemicals by utilizing the residual aeration and agitation or hydraulic flow within the tank. This enables the chemical precipitation reaction (such as the formation of insoluble substances from phosphates and metal ions) and the charge neutralization and destabilization process of colloids to begin earlier and undergo a longer hydraulic retention time.

[0141] Subsequently, the water carrying the formed micro-flocculations enters a specially designed flocculation tank 9, where the flocs grow and coarsen. The addition of the coagulant aid also follows a two-stage process to adapt to the flocculation requirements at different stages.

[0142] Thus, by premixing and reacting in the second aerobic tank 8, the effective contact reaction time between the reagent and the pollutants is extended. This helps to improve the completeness of the chemical precipitation reaction, resulting in more thorough phosphate removal and thus enhancing the stability and limit level of the total phosphorus removal rate.

[0143] Two-stage dosing helps form denser, stronger flocs. The micro-flocs formed in the second aerobic tank 8 can serve as crystal nuclei in the subsequent flocculation tank 9. With the bridging effect of the coagulant, they can more efficiently capture and coagulate fine particles, generating flocs that are easier to settle and separate, thereby reducing effluent turbidity and suspended solids.

[0144] Furthermore, embedding chemical dosing points at the end of the biochemical process transforms biochemical treatment and chemical enhancement treatment from two independent steps into a smooth, mutually reinforcing, continuous process. This helps maintain the continuity and overall efficiency of the treatment process.

[0145] In one possible implementation, stirring devices are installed in the first anoxic tank 1, the second anoxic tank 6, and the flocculation tank 9 to promote the reaction. Specifically, the stirring devices include, but are not limited to, submersible mixers or hydraulic propellers, to prevent the deposition of activated sludge or suspended packing material and to promote thorough mixing of wastewater and microorganisms.

[0146] In one possible implementation, the wastewater treatment apparatus further includes a dissolved air flotation (DAF) tank 93, which is located downstream of and connected to the flocculation tank 9. A DAF device 94 is disposed in the DAF tank 93 for removing suspended solids from the DAF tank 93.

[0147] See Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown. This application also provides a control method for a wastewater treatment device. The control method includes: S1 obtains water parameters and air flow rate.

[0148] S2 calculates the aeration volume based on water parameters.

[0149] S3 controls the aeration device based on aeration volume and air flow rate.

[0150] In this way, by linking the aeration rate with real-time process requirements (temperature, ammonia nitrogen load), the first aerobic tank can be kept in a dissolved oxygen environment suitable for nitrifying bacteria under different influent conditions, thereby improving the stability of ammonia nitrogen removal efficiency and reducing the risk of excessive ammonia nitrogen concentration in the effluent.

[0151] In one possible implementation, calculating the aeration rate based on water parameters includes: S21 calculates the dissolved oxygen demand and chemical oxygen demand based on water parameters.

[0152] S22 calculates the oxygenation efficiency based on water parameters and dissolved oxygen requirements.

[0153] S23 calculates the aeration volume based on oxygenation efficiency and chemical oxygen demand.

[0154] This provides a mechanism-based, verifiable calculation method. Instead of using a fixed empirical value, the oxygenation efficiency is calculated as a dynamic variable based on real-time water parameters and process targets (dissolved oxygen demand). This makes the calculation of aeration volume more closely reflect changes in actual operating conditions, improving the system's adaptability and control accuracy.

[0155] In one possible implementation, the aeration device for controlling the wastewater treatment device based on the aeration volume and air flow rate includes: S31 determines whether the aeration volume is less than the air flow rate.

[0156] S32 controls the air supply of the aeration device.

[0157] S33 controls the aeration device to stop supplying air.

[0158] Execute S31. If S31 is satisfied, i.e., when the aeration volume is less than the air flow rate, then execute S32. If S31 is not satisfied, i.e., when the aeration volume is greater than or equal to the air flow rate, then execute S33.

[0159] Aeration devices are the main energy-consuming equipment in wastewater treatment plants. Adopting the control methods described above, instead of continuous operation, directly reduces their operating time, thus saving energy. At the same time, reducing frequent frequency conversion or valve adjustments helps extend the service life of key moving equipment. It also reduces the damage to the denitrification environment caused by high dissolved oxygen recirculation to the upstream anoxic tank.

[0160] In one possible implementation, the control method further includes, after acquiring the water parameters and air flow rate: S4 obtains carbon source replenishment.

[0161] S5 calculates the carbon source requirement for the second anoxic pool based on water parameters.

[0162] S6 controls the carbon source replenishment device based on the carbon source demand and the carbon source replenishment amount.

[0163] In this way, the carbon source dosage is dynamically linked to the actual nitrate nitrogen load, enabling on-demand addition and avoiding the waste or insufficiency that may result from fixed-ratio or experience-based addition, thus reducing carbon source reagent consumption. At the same time, precise control of the carbon source dosage ensures that there is enough carbon source to complete denitrification and meet total nitrogen emission standards, while preventing the risk of increased COD in the effluent due to excessive carbon source.

[0164] In one possible implementation, the controller is configured to control the carbon source replenishment device based on the carbon source demand and the carbon source replenishment amount, specifically including: S61 determines whether the carbon source demand is less than the carbon source replenishment.

[0165] S62 controls the operation of the carbon source replenishment device.

[0166] S63 controls the carbon source replenishment device to stop operating.

[0167] Execute S61. If S61 is satisfied, i.e., the carbon source demand is less than the carbon source replenishment, then execute S62. If S31 is not satisfied, i.e., the carbon source demand is greater than or equal to the carbon source replenishment, then execute S63.

[0168] This allows for on-demand carbon source addition, reducing both excessive and insufficient addition, thus ensuring emissions meet standards.

[0169] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wastewater treatment device, characterized in that, include: First anoxic pool; First aerobic tank; It is located downstream of the first anoxic pool along the direction of water flow and is connected to the first anoxic pool; An aeration device is connected to the first aerobic tank and is used to supply air into the first aerobic tank; A water body detection device is used to detect water body parameters, including the temperature of the first aerobic tank, the ammonia nitrogen concentration of the water entering the first aerobic tank, and the ammonia nitrogen concentration of the water flowing out of the first aerobic tank. An air flow detection device is used to detect the air flow of the aeration device; The controller; the aeration device, the water body detection device, and the air flow detection device are communicatively connected to the controller; The controller is configured to: acquire water parameters and air flow rate; calculate aeration volume based on the water parameters; and control the aeration device based on the aeration volume and air flow rate.

2. The wastewater treatment device according to claim 1, characterized in that, The controller is configured to calculate the aeration rate based on the water parameters, including: Based on the water parameters, calculate the dissolved oxygen demand and the oxygen demand of the first aerobic tank; calculate the oxygenation efficiency based on the water parameters and the dissolved oxygen demand; calculate the aeration rate based on the oxygenation efficiency and the oxygen demand of the first aerobic tank.

3. The wastewater treatment device according to claim 1, characterized in that, The controller is configured to control the aeration device based on the aeration volume and the air flow rate, including: Determine whether the aeration volume is less than the air flow rate; when the aeration volume is less than the air flow rate, control the aeration device to supply air; when the aeration volume is greater than or equal to the air flow rate, control the aeration device to stop supplying air.

4. The wastewater treatment device according to claim 1, characterized in that, Also includes: The second anoxic pool is located downstream of the first aerobic pool and is connected to the first aerobic pool; A carbon source replenishment device is connected to the second anoxic pool and is used to replenish the carbon source into the second anoxic pool.

5. The wastewater treatment device according to claim 4, characterized in that, The water parameters also include the nitrate nitrogen concentration entering the first anoxic pool and the nitrate nitrogen concentration flowing out of the first anoxic pool; The wastewater treatment device also includes: a carbon source flow detection device, used to detect the amount of carbon source replenishment from the carbon source replenishment device; The controller is communicatively connected to the carbon source replenishment device and the carbon source flow detection device. After acquiring water parameters and air flow, the controller is further configured to: acquire the carbon source replenishment amount; calculate the carbon source demand of the second anoxic pool based on the water parameters; and control the carbon source replenishment device based on the carbon source demand and the carbon source replenishment amount.

6. The wastewater treatment device according to claim 4, characterized in that, Also includes: The second aerobic tank is located downstream of the second anoxic tank and is connected to the second anoxic tank; The aeration device is also connected to the second anoxic tank and is used to supply oxygen to the second anoxic tank.

7. The wastewater treatment device according to claim 6, characterized in that, Also includes: Flocculation pool; A flocculant dosing device is connected to the flocculation tank and the second aerobic tank. The flocculant dosing device is used to add flocculant to the flocculation tank and the second aerobic tank. A coagulant dosing device is connected to the flocculation tank and the second aerobic tank. The coagulant dosing device is used to add coagulant to the flocculation tank and the second aerobic tank.

8. A control method for a wastewater treatment device, characterized in that: For use in the wastewater treatment apparatus according to any one of claims 1-7; The wastewater treatment device includes an aeration device; the control method includes: Obtain water parameters and air flow rate; Calculate the aeration rate based on the water body parameters; The aeration device is controlled according to the aeration volume and air flow rate.

9. The control method according to claim 8, characterized in that, The calculation of aeration volume based on the water body parameters includes: calculating the dissolved oxygen demand and the oxygen demand of the first aerobic tank based on the water body parameters; calculating the oxygenation efficiency based on the water body parameters and the dissolved oxygen demand; and calculating the aeration volume based on the oxygenation efficiency and the oxygen demand of the first aerobic tank. And / or, the aeration device for controlling the wastewater treatment device based on the aeration volume and air flow rate includes: determining whether the aeration volume is less than the air flow rate; when the aeration volume is less than the air flow rate, controlling the aeration device to supply air; when the aeration volume is greater than or equal to the air flow rate, controlling the aeration device to stop supplying air.

10. The control method according to claim 8, characterized in that, The wastewater treatment device further includes: a second anoxic tank located downstream of the first aerobic tank and connected to the first aerobic tank; a carbon source replenishment device connected to the second anoxic tank and used to replenish carbon source into the second anoxic tank; and a carbon source flow detection device, which is used to detect the amount of carbon source replenished by the carbon source replenishment device. The control method further includes, after acquiring the water parameters and air flow rate: Obtain carbon source replenishment; Calculate the carbon source requirement for the second anoxic pool based on the water parameters; The carbon source replenishment device is controlled according to the carbon source demand and the carbon source replenishment amount.

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