A sewage treatment anti-blocking carbon release equipment, a dual-mode adaptive control system and method

Abstract

The application discloses sewage treatment anti-blocking carbon release equipment, a double-mode adaptive control system and a method, which comprises a skid-mounted heat preservation box body and a pretreatment unit, an anoxic moving bed biofilm reactor pool, an aerobic moving bed biofilm reactor pool and a solid-liquid separation unit. An internal reflux pump is arranged between the two reactor pools. A carbon source storage tank and a carbon source metering pump are further arranged in the box body. The internal reflux heat tracing carbon release sleeve assembly comprises an outer pipe and an inner pipe coaxially arranged in the inner pipe. The liquid outlet is arranged inside the liquid outlet of the outer pipe and coaxially arranged with the liquid outlet of the outer pipe. The carbon source in the outer pipe is heat traced by the biological reaction heat carried by the internal reflux liquid, effectively solving the problem that the fine-diameter carbon source adding pipeline is prone to freezing in cold regions. The carbon source is fully mixed with the warm reflux liquid in the pipeline and then enters the reactor pool, realizing the preheating and pre-dilution of the carbon source and avoiding the direct impact of the low-temperature and high-concentration carbon source on the MBBR suspended filler biofilm.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and more specifically, to a wastewater treatment anti-blocking carbon release equipment, a dual-modal adaptive control system, and a method. Background Technology

[0002] In high-altitude and cold regions, decentralized domestic wastewater treatment facilities generally face severe challenges such as small treatment scale, large fluctuations in influent flow, extremely low water temperatures in winter, and a lack of professional operation and maintenance capabilities. While biological treatment processes are widely used in such applications, under extreme low-temperature conditions, the enzyme activity within microorganisms is inhibited, and the metabolic rate decreases significantly, directly leading to a decline in the treatment efficiency of nitrifying and denitrifying bacteria. Current technologies, in order to ensure that effluent ammonia nitrogen and total nitrogen levels meet standards, often employ crude measures such as electrically heating to raise the water temperature or excessively adding external carbon sources. This not only significantly increases operating costs but also fails to fundamentally solve the systemic problem of low biological nitrogen removal efficiency under low-temperature conditions.

[0003] Existing carbon source addition and temperature control methods have insurmountable drawbacks in practical applications. On the one hand, due to the dispersed and small-scale nature of skid-mounted equipment, carbon source addition pipelines are typically small in diameter and have slow flow rates. Furthermore, since denitrification is often done intermittently, residual liquid in the pipes is highly susceptible to freezing and blockage in extremely cold environments during periods of inactivity. While electric heating is a conventional method, it is not only energy-intensive but also incurs high safety and management costs in remote, unattended scenarios, including cable aging, short-circuit fires, and maintenance difficulties. On the other hand, low temperatures increase wastewater viscosity and weaken its diffusion capacity. Traditional drip or spray addition methods can easily lead to excessively high local carbon source concentrations. For processes using moving bed biofilm reactors, this high-concentration environment can induce excessive proliferation of heterotrophic bacteria on the surface of the suspended packing material, disrupting the microecological balance between nitrifying and denitrifying bacteria within the biofilm and even producing substrate inhibition effects, ultimately reducing the overall nitrogen removal efficiency of the system.

[0004] Furthermore, current mainstream adaptive carbon source dosing control strategies largely rely on feedback signals from online redox potential or nitrate nitrogen sensors. However, in low-temperature sludge-water mixtures, sensor probes are highly susceptible to high-frequency noise, drift, or response hysteresis due to biofilm formation, ice crystal adhesion, or slowed ion migration rates. Existing closed-loop control algorithms typically rely on fixed absolute thresholds for judgment, lacking effective discrimination and fault-tolerance mechanisms for sensor data confidence. Once sensor signals become distorted, the control system will misjudge the operating conditions, leading to oscillations in carbon source dosing, such as over-dosing or interruption, severely impacting the long-term stable operation of wastewater treatment facilities in cold regions. Therefore, there is an urgent need for a precise carbon source dosing and control strategy that is adaptable to cold environments, low-energy, and interference-resistant. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of existing technologies and provide an anti-clogging carbon release equipment and a dual-modal control method for MBBR wastewater treatment in high-altitude and cold regions. It achieves antifreeze premixing by using the internal reflux liquid waste heat-tracing carbon source pipeline, and combines it with dual-modal adaptive control based on the second derivative of the ORP signal. This solves the problems of easy freezing and clogging of carbon source pipelines in MBBR systems in high-altitude and cold regions, impact of local high concentration of carbon source on biofilm, and loss of control due to low temperature sensor distortion.

[0006] The objective of this application is achieved through the following technical solution: In the first aspect, this application proposes a wastewater treatment anti-blocking carbon release equipment, including an internal reflux heat-tracing carbon release sleeve assembly, a skid-mounted insulated box 1, and a pretreatment unit 2, an anoxic moving bed biofilm reactor 3, an aerobic moving bed biofilm reactor 4, and a solid-liquid separation unit 5 arranged sequentially in the box. An internal reflux pump 16 is provided between the aerobic moving bed biofilm reactor tank 4 and the anoxic moving bed biofilm reactor tank 3; The container also contains a carbon source storage tank 7 and a carbon source metering pump 8; The internal reflux heat tracing carbon release sleeve assembly includes an outer tube 15 and an inner tube 13 coaxially inserted inside the outer tube; The inlet end of the outer pipe 15 is connected to the outlet of the internal reflux pump 16, and the outlet end of the outer pipe 15 extends below the designed liquid level of the anoxic moving bed biofilm reactor tank 3. The inlet end of the inner tube 13 is connected to the outlet of the carbon source metering pump 8, and the outlet end of the inner tube 13 is located inside the outlet end of the outer tube 15, and the outlet of the inner tube and the outlet of the outer tube are arranged coaxially. The carbon source is discharged into the reflux liquid in the outer pipe 15 through the inner pipe 13 for heat exchange and mixing.

[0007] In one possible embodiment, a duckbill-type check valve 17 is fastened to the liquid outlet end of the inner tube 13. The duckbill-type check valve 17 is made of low-temperature resistant special rubber or polytetrafluoroethylene.

[0008] In one possible embodiment, a three-way junction is provided between the liquid inlet end of the inner tube 13 and the outlet pipe of the carbon source metering pump 8. A manual antifreeze purge valve 14 is connected to the bypass of the three-way junction. The manual antifreeze purge valve 14 is connected to an external compressed air source and is used to purge residual carbon source when the equipment is shut down.

[0009] In one possible embodiment, the ratio of the length L of the inner tube 13 passing inside the outer tube 15 to the inner diameter D of the outer tube satisfies L / D≥30.

[0010] In one possible embodiment, the outer wall of the inner tube 13 is provided with a plurality of centering brackets 18 spaced apart along the axial direction. The centering brackets 18 are used to fix the inner tube 13 on the central axis of the outer tube 15. The inlet of the outer tube 15 and the inner tube 13 is provided with a sealing structure 19 to prevent the backflow liquid in the outer tube from leaking along the outer wall of the inner tube.

[0011] In a second aspect, this application proposes a dual-modal adaptive control system based on the first aspect, including a PLC controller 12, an influent flow meter 11 that is communicatively connected to the PLC controller 12, an oxidation-reduction potential sensor 10 and a carbon source metering pump 8 installed in the anoxic moving bed biofilm reactor 3. The PLC controller 12 is internally configured with a signal filtering and calculation unit and a dual-mode logic switching unit. The signal filtering and calculation unit is used to preprocess the redox potential signal, and the dual-mode logic switching unit is used to switch between the normal closed-loop mode and the feedforward emergency mode according to the signal quality.

[0012] Thirdly, this application proposes a dual-modal adaptive control method for the dual-modal adaptive control system applied in the second aspect, comprising: Under normal closed-loop mode, the signal filtering calculation unit performs smoothing filtering on the redox potential signal within a set sliding time window, and continuously calculates the first derivative of the filtered signal. and second derivative ; When determining the first derivative If the second derivative is detected for the first time within a continuous sampling period after the value falls below the preset negative extreme value threshold. When a value changes from negative to positive and remains positive or zero for N consecutive sampling points after crossing zero, the inflection point of denitrification is determined to have been reached, where N≥2; The PLC controller sends a signal to the carbon source metering pump to reduce the frequency or stop the pump.

[0013] In one possible embodiment, the dual-modal control method further includes: When the signal filtering and calculation unit determines that any preset condition is met, the redox potential sensor is deemed to be faulty. The dual-mode logic switching unit cuts off the redox potential feedback loop and switches to feedforward emergency mode; In the feedforward emergency mode, the PLC controller drives the carbon source metering pump to add carbon source by multiplying the real-time flow rate Q collected by the inlet flow meter by the preset carbon source equivalent constant K in an open-loop feedforward manner. The preset conditions include: The variance of the redox potential signal within the sliding time window is lower than the set distortion judgment threshold; The absolute value of the first derivative exceeds the hardware jump threshold; Within the set long-term window, the cumulative change in the filtered oxidation-reduction potential signal is lower than the minimum threshold, and the change in the influent flow rate or the frequency of the carbon source metering pump exceeds the set value.

[0014] In one possible embodiment, the carbon source equivalent constant K is determined by calculating based on the chemical oxygen demand (COD) equivalent of the carbon source and the theoretical carbon requirement for denitrification, and then introducing a safety factor for correction.

[0015] In one possible embodiment, the duration of the sliding time window is 5 seconds, and a smooth signal is obtained by using a 5-point moving average filtering method. The preset negative extreme value threshold range is -1.5mV / s to -3.0mV / s; N takes the value of 3 in N consecutive sampling points.

[0016] The main solution and its various further alternatives described above can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application; furthermore, the non-conflicting alternatives in this application can also be freely combined with each other and with other alternatives. Those skilled in the art, after understanding the solution of this application, will realize from the prior art and common general knowledge that there are many combinations, all of which are technical solutions to be protected in this application, and will not be exhaustively listed here.

[0017] This application discloses a wastewater treatment anti-clogging carbon release equipment, a dual-modal adaptive control system, and a method, including a skid-mounted insulated box and pretreatment unit, an anoxic moving bed biofilm reactor, an aerobic moving bed biofilm reactor, and a solid-liquid separation unit. An internal reflux pump is provided between the two reactors, and a carbon source storage tank and a carbon source metering pump are also provided inside the box. The internal reflux heat-tracing carbon release sleeve assembly includes an outer pipe and an inner pipe coaxially inserted inside the outer pipe. The liquid outlet is located inside the liquid outlet of the outer pipe and is coaxially arranged with the liquid outlet of the outer pipe. The heat of biological reaction carried by the internal reflux liquid itself is used to heat the carbon source in the outer pipe, which effectively solves the problem of easy freezing and clogging of small-diameter carbon source addition pipelines in high-altitude and cold regions. After the carbon source is fully mixed with the warm reflux liquid in the pipe, it enters the reaction tank, realizing the preheating and pre-dilution of the carbon source, and avoiding the direct impact of low-temperature, high-concentration carbon source on the MBBR suspended packing biofilm. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1A schematic diagram of a wastewater treatment anti-carbon release device according to an embodiment of this application is shown.

[0020] Figure 2 A schematic diagram of the internal reflux heat tracing carbon release sleeve assembly proposed in an embodiment of this application is shown.

[0021] Figure 3 A logic flowchart of the dual-modal control method proposed in an embodiment of this application is shown.

[0022] Attached reference numerals: 1-Skid-mounted insulated enclosure; 2-Pretreatment unit; 3-Anoxic moving bed biofilm reactor; 4-Aerobic moving bed biofilm reactor; 5-Solid-liquid separation unit; 6-Equipment room; 7-Carbon source storage tank; 8-Carbon source metering pump; 9-Aeration blower; 10-Oxidation-reduction potential sensor; 11-Inlet flow meter; 12-PLC controller; 13-Inner pipe; 14-Manual antifreeze purge valve; 15-Outer pipe; 16-Internal reflux pump; 17-Duckbill check valve; 18-Centering support; 19-Sealing structure. Detailed Implementation

[0023] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0024] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] To address the existing technical problems, this application proposes an anti-blockage carbon release equipment, a dual-modal adaptive control system, and a method for wastewater treatment. The antifreeze premixing is achieved through a carbon source pipeline with residual heat from the internal reflux liquid. Combined with dual-modal adaptive control based on the second derivative of the ORP signal, the problems of easy freezing and blockage of carbon source pipelines in MBBR systems in high-altitude and cold regions, impact of local high-concentration carbon sources on biofilms, and loss of control due to low-temperature sensor distortion are solved.

[0026] Please refer to Figure 1 , Figure 1 The diagram shows a wastewater treatment anti-blocking carbon release equipment proposed in an embodiment of this application, including an internal reflux heat-tracing carbon release sleeve assembly, a skid-mounted insulated box 1, and a pretreatment unit 2, an anoxic moving bed biofilm reactor 3, an aerobic moving bed biofilm reactor 4, and a solid-liquid separation unit 5 arranged sequentially in the box. An internal reflux pump 16 is provided between the aerobic moving bed biofilm reactor tank 4 and the anoxic moving bed biofilm reactor tank 3; The container also contains a carbon source storage tank 7 and a carbon source metering pump 8; The internal reflux heat tracing carbon release sleeve assembly includes an outer tube 15 and an inner tube 13 coaxially inserted inside the outer tube; The inlet end of the outer pipe 15 is connected to the outlet of the internal reflux pump 16, and the outlet end of the outer pipe 15 extends below the designed liquid level of the anoxic moving bed biofilm reactor tank 3. The inlet end of the inner tube 13 is connected to the outlet of the carbon source metering pump 8, and the outlet end of the inner tube 13 is located inside the outlet end of the outer tube 15, and the outlet of the inner tube and the outlet of the outer tube are arranged coaxially. The carbon source is discharged into the reflux liquid in the outer pipe 15 through the inner pipe 13 for heat exchange and mixing.

[0027] The main structure of this application is a skid-mounted insulated box 1, with a 50-100mm thick polyurethane foam insulation layer on the outside. Inside, along the water flow direction, a pretreatment unit 2, an anoxic moving bed biofilm reactor 3, an aerobic moving bed biofilm reactor 4, and a solid-liquid separation unit 5 are integrated sequentially. The aerobic moving bed biofilm reactor 4 and the anoxic moving bed biofilm reactor 3 are hydraulically connected through an internal reflux pump 16, forming an internal reflux channel for the nitrification liquid. At the same time, a carbon source storage tank 7 and a matching carbon source metering pump 8 are independently installed in the equipment room 6, forming an external carbon source dosing system.

[0028] Figure 2 The diagram shows a schematic of the internal reflux heat-tracing carbon release sleeve assembly proposed in this application. The internal reflux heat-tracing carbon release sleeve assembly includes an outer tube 15 and an inner tube 13, which are arranged in a strictly coaxial nested manner. The outer tube 15 serves as the main channel, and its inlet end is rigidly connected to the outlet of the internal reflux pump 16. The internal reflux pump is used to pump the mixed liquid rich in bioreaction heat in the aerobic moving bed biofilm reactor 4 into the outer tube. The outlet end of the outer tube 15 not only extends below the designed liquid level of the anoxic moving bed biofilm reactor 3, but also adopts a submerged discharge method. This effectively avoids reoxygenation during the carbon source drop process and maintains the stability of the anoxic environment.

[0029] Meanwhile, the inner tube 13 serves as a carbon source transport channel, with its inlet end connected to the outlet of the carbon source metering pump 8, while its outlet end extends into the interior of the outlet end of the outer tube 15. The outlets of the inner and outer tubes are coaxially aligned. This "tube-in-tube" design ensures that the low-temperature carbon source must first flow through the high-temperature reflux liquid area inside the outer tube before entering the anoxic tank. During this process, the carbon source absorbs heat from the reflux liquid to achieve preheating, effectively preventing the cold shock to microorganisms caused by the direct entry of the low-temperature carbon source into the reactor.

[0030] In summary, this equipment, through its internal reflux heat-tracing carbon release sleeve assembly, transforms the original energy-consuming electric heat tracing antifreeze into a passive antifreeze system utilizing process waste heat. Furthermore, its coaxial jet structure achieves the dual functions of "preheating + premixing" of the carbon source. This deep coupling of structural features and control strategy not only solves the problem of easy freezing and clogging of small-diameter carbon source pipelines in high-altitude and cold regions but also significantly reduces the system's operating energy consumption and maintenance difficulty, making it particularly suitable for decentralized, unattended wastewater treatment scenarios in high-altitude and cold regions.

[0031] The liquid outlet end of the inner tube 13 is fitted with a duckbill-type check valve 17, which is made of low-temperature resistant special rubber or polytetrafluoroethylene.

[0032] This application features a duckbill-type check valve 17 securely fitted at the outlet end of the inner tube 13. This check valve abandons the traditional metal spring structure, instead employing a low-temperature resistant special rubber (preferably fluororubber) or polytetrafluoroethylene material in a single integral molding process. Its lip structure allows for self-tightening closure using the hydrostatic pressure within the outer tube 15 when the carbon source metering pump 8 is stopped, while opening relies on fluid force when the pump is started. Even in extremely cold conditions of -25°C or lower, the valve body maintains good elastic recovery and chemical stability, preventing sealing failure or valve port adhesion due to low-temperature embrittlement. Simultaneously, its smooth hydrophobic surface effectively prevents the adhesion and growth of microorganisms.

[0033] A three-way joint is provided between the liquid inlet end of the inner tube 13 and the outlet pipe of the carbon source metering pump 8. A manual antifreeze purging valve 14 is connected to the bypass of the three-way joint. The manual antifreeze purging valve 14 is connected to an external compressed air source and is used to purge residual carbon source when the equipment is shut down.

[0034] This equipment has a three-way connector with a bypass at the connection between the liquid inlet end of the inner pipe 13 (located in the dry equipment room inside the insulated box) and the outlet of the carbon source metering pump 8. This bypass is specifically connected to the manual antifreeze purging valve 14. This valve can be connected to an external compressed air source when not in operation. When the system faces long-term power outages or winter maintenance, maintenance personnel can connect a compressed air hose and open the valve to use high-pressure gas to force the residual carbon source trapped in the inner pipe 13 and the downstream duckbill check valve 17 to be purged into the anoxic pool 3.

[0035] The ratio of the length L through which the inner tube 13 passes inside the outer tube 15 to the inner diameter D of the outer tube satisfies L / D≥30.

[0036] This equipment imposes strict quantitative limits on the length of the inner tube 13 within the outer tube 15, namely, the ratio of the travel length L to the inner diameter D of the outer tube must satisfy L / D≥30. This ratio is a critical value derived from heat balance calculations under extremely cold conditions: taking the inner tube as an example of transporting a 20% to 30% concentration sodium acetate solution, when the outer tube 15 introduces an internal reflux liquid taken from the aerobic tank and rich in biological reaction heat, the geometric constraint of L / D≥30 can ensure sufficient convective heat transfer time and contact area between the carbon source and the heat source.

[0037] Multiple centering supports 18 are provided axially along the outer wall of the inner tube 13. The centering supports 18 are used to fix the inner tube 13 on the central axis of the outer tube 15. A sealing structure 19 is provided at the joint entrance of the outer tube 15 and the inner tube 13 to prevent the backflow liquid in the outer tube from leaking along the outer wall of the inner tube.

[0038] This application provides multiple centering supports 18 spaced axially along the outer wall of the inner tube 13. These centering supports 18 are preferably made of non-metallic materials with low thermal conductivity and corrosion resistance, such as nylon or polytetrafluoroethylene, and are arranged in a cross-shaped or ring-shaped structure within the annular gap between the inner and outer tubes. This spaced fixing method effectively prevents the inner tube from becoming eccentric or stuck to the wall due to water flow impact or gravity settling, and prevents the formation of "thermal bridges" due to insufficient local contact thermal resistance or heat exchange dead zones due to uneven gaps, ensuring that the carbon source in the inner tube is uniformly heated by the return liquid from the outer tube.

[0039] This application provides a sealing structure 19 at the joint inlet of the outer tube 15 and the inner tube 13. The sealing structure 19 can be a sealing form such as an O-ring, sealing flange, sealant or stuffing box. The sealing sleeve is installed at the part where the inner tube 13 enters the outer tube 15 to seal the assembly gap between the outer wall of the inner tube 13 and the wall of the outer tube 15. Since the inner tube 13 needs to enter through the wall of the outer tube 15 and extend along the outer tube axial direction to the liquid outlet, there must be a joint gap between the two. The setting of the sealing structure 19 can ensure that the return liquid flowing in the outer tube 15 can only flow normally along the outer tube flow channel and be discharged from the liquid outlet, and will not leak into the outside of the casing or the equipment room 6 through the gap between the outer wall of the inner tube 13 and the outer tube 15. This avoids water loss and heat exchange effect reduction caused by return liquid leakage, and at the same time prevents the leakage liquid from corroding the pipe fittings and affecting the dosing accuracy of the carbon source metering pump 8.

[0040] This application also proposes a dual-mode adaptive control system based on anti-blocking carbon release equipment, characterized in that it includes a PLC controller 12, an influent flow meter 11 that is communicatively connected to the PLC controller 12, an oxidation-reduction potential sensor 10 and a carbon source metering pump 8 installed in the anoxic moving bed biofilm reactor tank 3. The PLC controller 12 is internally configured with a signal filtering and calculation unit and a dual-mode logic switching unit. The signal filtering and calculation unit is used to preprocess the redox potential signal, and the dual-mode logic switching unit is used to switch between the normal closed-loop mode and the feedforward emergency mode according to the signal quality.

[0041] The dual-modal adaptive control system uses PLC controller 12 as the control core and constructs an intelligent control architecture. At the hardware connection level, PLC controller 12 establishes real-time bidirectional communication with influent flow meter 11, which monitors influent load, oxidation-reduction potential sensor 10, which reflects the biochemical reaction state of anoxic tank 3, and carbon source metering pump 8, which performs carbon source addition, through standard industrial bus or analog input module.

[0042] The signal filtering and calculation unit is not a simple signal acquisition module, but rather incorporates specific digital signal processing algorithms. Given that low-temperature mud-water mixtures in high-altitude and cold regions can easily cause high-frequency noise or drift in the ORP probe signal, this unit first preprocesses the acquired raw ORP signal. Figure 3 The diagram illustrates the logic flowchart of the dual-modal control method proposed in this application. The system sets a sliding time window, uses a moving average filtering method to smooth the original signal, and continuously calculates the first derivative of the filtered signal based on this. and second derivative This allows for the extraction of morphological features that reflect the changing trend of the denitrification reaction rate, while filtering out invalid interference caused by probe icing or electrode polarization.

[0043] The dual-mode logic switching unit intelligently and seamlessly switches between the normal closed-loop mode and the feedforward emergency mode based on the signal quality assessment results output by the signal filtering and calculation unit. Under normal operating conditions, when the ORP signal quality is reliable, the system operates in the normal closed-loop mode: using the aforementioned second-order derivative criterion, it accurately captures the "inflection point" of the denitrification reaction, thereby timely reducing the frequency of the carbon source metering pump 8 or shutting it down, avoiding excessive carbon source addition caused by the low-temperature hysteresis of the traditional absolute threshold method. However, when the signal filtering and calculation unit detects that the ORP signal variance is too low, the derivative jump exceeds the limit, or there is no change over a long period and it does not adjust with the operating conditions, it determines that the sensor has failed. The dual-mode logic switching unit immediately cuts off the unreliable ORP feedback loop and automatically switches to the feedforward emergency mode. In this mode, the system abandons its dependence on the state of the reaction end and instead uses the real-time flow rate Q collected by the influent flow meter 11, multiplied by the preset carbon source equivalent constant K, to drive the carbon source metering pump 8 in an open-loop feedforward manner. This ensures that even in the extreme case of complete sensor failure, the system can still maintain basic denitrification function based on the influent load and issue an alarm signal to wait for manual intervention.

[0044] This application also proposes a dual-modal adaptive control method for dual-modal adaptive control systems, including: Under normal closed-loop mode, the signal filtering calculation unit performs smoothing filtering on the redox potential signal within a set sliding time window and continuously calculates the first derivative of the filtered signal. and second derivative ; When determining the first derivative If the second derivative is detected for the first time within a continuous sampling period after the value falls below the preset negative extreme value threshold. When a value changes from negative to positive and remains positive or zero for N consecutive sampling points after crossing zero, the inflection point of denitrification is determined to have been reached, where N≥2; The PLC controller sends a signal to the carbon source metering pump to reduce the frequency or stop the pump.

[0045] Under normal closed-loop mode, the system first executes a signal preprocessing program optimized for high-altitude and cold-weather conditions. The PLC controller 12 acquires the raw millivolt ORP signal from the anoxic moving bed biofilm reactor 3 in real time at a sampling frequency of 1Hz. Given the low water temperature and high viscosity of the sludge mixture in high-altitude and cold regions, the ORP probe is susceptible to high-frequency noise due to biofilm adhesion or ice crystal interference. Therefore, the signal filtering calculation unit immediately initiates a moving average filtering algorithm. The system sets a 5-second time sliding window and performs an arithmetic average of 5 consecutive sampling points within this window to generate a smoothed and filtered signal.

[0046] This application introduces a composite criterion combining first-order derivative threshold triggering and second-order derivative shape recognition. The signal filtering calculation unit is based on smoothed signals. Calculate its first derivative continuously and second derivative The system presets a negative extreme value threshold. When detected When the value is below this threshold, it indicates that the denitrification reaction is in progress and the rate is in a phase of rapid increase.

[0047] when When a value first crosses zero from a negative value and becomes positive, it indicates that the increasing trend of the denitrification rate begins to weaken, and the system determines that the inflection point of the reaction has been reached. To eliminate false inflection points caused by signal jitter and ensure the robustness of the judgment, the system has added an N-point confirmation mechanism. Only when... The system only confirms that it has reached the denitrification endpoint when the value remains positive or zero for three consecutive sampling cycles after crossing the zero point. At this time, the PLC controller 12 immediately sends a stop or frequency reduction command to the carbon source metering pump 8.

[0048] Dual-modal control methods also include: When the signal filtering and calculation unit determines that any preset condition is met, the redox potential sensor is deemed to be faulty. The dual-mode logic switching unit cuts off the redox potential feedback loop and switches to feedforward emergency mode; In the feedforward emergency mode, the PLC controller drives the carbon source metering pump to add carbon source by multiplying the real-time flow rate Q collected by the inlet flow meter by the preset carbon source equivalent constant K in an open-loop feedforward manner. The preset conditions include: The variance of the redox potential signal within the sliding time window is lower than the set distortion judgment threshold; The absolute value of the first derivative exceeds the hardware jump threshold; Within the set long-term window, the cumulative change in the filtered oxidation-reduction potential signal is lower than the minimum threshold, and the change in the influent flow rate or the frequency of the carbon source metering pump exceeds the set value.

[0049] This application constructs a multi-dimensional signal confidence evaluation system. When the signal filtering calculation unit determines that any of the following preset conditions are met, the ORP sensor is deemed to have failed, and mode switching is triggered: The first dimension is signal freeze determination: the signal filtering calculation unit uses a 60-second time window to calculate the variance of the ORP signal within the window in real time. When 3 consecutive windows A value ≤0.5 (distortion threshold) indicates that the signal fluctuation is minimal or even linear. In anoxic environments where biochemical reactions are ongoing, ORP will inevitably fluctuate naturally due to the influence of microbial metabolism. If the signal remains unchanged for a long period, it can be determined that the signal is frozen due to the probe being encased in ice crystals or a circuit malfunction.

[0050] The second dimension is hardware transition detection: the system monitors the first derivative of the ORP signal in real time. .when When the signal reaches a value of mV / s (hardware transition threshold), it is determined that a non-physical abrupt change has occurred.

[0051] The third dimension is the dynamic response hysteresis determination: The system sets a relatively long time window and calculates the cumulative change ΔORP of the filtered ORP signal within that period. If ΔORP ≤ 5mV (minimum threshold), it indicates that the sensor is extremely insensitive to changes in operating conditions. Simultaneously, the system compares the amplitude of changes in influent flow rate or carbon source metering pump frequency during the same period. If the influent load or dosage changes significantly, but the ORP signal shows no response, it confirms that the sensor has severe response hysteresis or loss of sensitivity.

[0052] Once any of the above conditions are met, the dual-mode logic switching unit immediately cuts off the unreliable ORP feedback loop, and the system seamlessly switches to feedforward emergency mode. In this mode, the PLC controller 12 no longer relies on the biochemical signal from the reaction end, but instead uses the real-time flow rate Q collected by the influent flow meter 11, multiplied by a preset carbon source equivalent constant K, according to... The carbon source metering pump 8 is driven in an open-loop feedforward manner. Among them, the constant... It is an empirical value calculated based on the carbon source COD equivalent, the theoretical carbon requirement for denitrification, and the target water quality.

[0053] The carbon source equivalent constant K is determined by calculating the equivalent of the carbon source's chemical oxygen demand (COD) and the theoretical carbon requirement for denitrification, and then correcting it with a safety factor.

[0054] The determination of the carbon source equivalent constant K is not based on a rough setting through empirical trial and error, but rather on theoretical derivation and correction according to the principles of chemometrics and engineering safety redundancy. First, the COD equivalent (CCOD) of the carbon source used is measured. Then, based on the principles of denitrification biochemical stoichiometry, the theoretical COD required to remove 1g of nitrate nitrogen is determined. Based on this, and combined with the target total nitrogen removal (CTN), the theoretical carbon source volume required to achieve complete denitrification per cubic meter of wastewater is calculated. Considering factors such as reduced microbial metabolic rate and decreased mass transfer efficiency in cold environments, a safety factor greater than 1 is ultimately introduced for correction.

[0055] In one possible embodiment, the duration of the sliding time window is 5 seconds, and a smooth signal is obtained by using a 5-point moving average filtering method. The preset negative extreme value threshold range is -1.5mV / s to -3.0mV / s; N takes the value of 3 in N consecutive sampling points.

[0056] When the PLC acquires the ORP signal at a frequency of 1Hz, selecting a 5-second sliding time window and using a 5-point moving average filtering method can effectively suppress high-frequency noise and signal drift of the sensor in low-temperature environments while preserving the morphological change characteristics of the ORP curve at the inflection point of the denitrification process. Limiting the threshold of the negative extreme value of the first derivative to the range of -1.5mV / s to -3.0mV / s can accurately match the range of ORP decline slope caused by increased sewage viscosity and slowed denitrification rate in high-altitude and cold regions, avoiding false triggering due to an excessively wide threshold or missed detection due to an excessively narrow threshold. Fixing the number of continuous judgment sampling points N to 3 ensures that the state of the second derivative turning from negative to positive and maintaining a positive value has sufficient statistical significance under the premise of filtering out instantaneous interference.

[0057] Example 1: This embodiment focuses on a skid-mounted wastewater treatment plant with a daily treatment capacity of 30 m³ / d in cold regions, showcasing the parameter selection and thermodynamic verification of the internal recirculation heat tracing and carbon release sleeve assembly under specific operating conditions. The skid-mounted insulated enclosure 1 is externally covered with a 50-100 mm thick polyurethane foam insulation layer, internally integrating a pretreatment unit 2, an anoxic moving bed biofilm reactor 3, and an aerobic moving bed biofilm reactor 4. In the biochemical reaction section, HDPE suspended packing material with an effective specific surface area greater than 500 m² / m³ is added, with the filling rate controlled at 40% to ensure sufficient biological holding capacity even at low water temperatures. The internal recirculation pump 16 is designed with a flow rate of 200% of the influent flow rate (i.e., 60 m³ / d). This high recirculation ratio not only ensures the nitrification liquor recirculation requirement but also provides a sufficient heat source flow for subsequent sleeve heating.

[0058] The specific implementation parameters of the internal reflux heat-tracing carbon release sleeve assembly are as follows: the outer pipe 15 is made of DN80 UPVC material, and the inner pipe 13 is made of DN15 PE water supply pipe. The outlet end of the outer pipe 15 extends vertically downward to 0.5 meters below the liquid surface of the anoxic moving bed biofilm reactor tank 3, achieving submerged discharge and preventing reoxygenation by water drop. To ensure that the inner pipe 13 is located in the center of the outer pipe to obtain a uniform heat exchange effect, a set of nylon cross-shaped centering brackets 18 are installed on its outer wall every 0.5 meters. The duckbill check valve 17 at the end of the inner pipe 13 is integrally die-cast with fluororubber. This material maintains good elasticity at a low temperature of -25℃ and can reliably close its lip using the water pressure of the outer pipe when the carbon source metering pump 8 stops, preventing backflow of the reflux liquid.

[0059] This embodiment quantitatively verifies the antifreeze performance using a rigorous one-dimensional steady-state heat transfer model. Under extreme conditions (ambient temperature -25℃), the internal reflux liquid from the aerobic moving bed biofilm reactor 4, rich in microbial metabolic heat, maintains a temperature of 10℃ to 12℃ (11℃ is used for calculation). The outer pipe 15 is wrapped with a 50 to 100 mm polyurethane insulation layer to reduce heat loss, and the inner pipe 13 maintains a 2.5-meter passage length inside (satisfying L / D≥30). Thermodynamic calculations show that after the carbon source (20% to 30% sodium acetate solution, freezing point below -15℃) flows through this heating section, the outlet temperature can be maintained above 5℃, completely eliminating the risk of freezing inside the pipe. Furthermore, during long-term equipment shutdown, the residual carbon source can be forcibly discharged into the tank by connecting compressed air through the DN15 manual antifreeze purge valve 14 at the liquid inlet end of the inner pipe, achieving thorough physical antifreeze protection.

[0060] Example 2: First, during the data acquisition and preprocessing stage, the PLC controller 12 acquires the raw millivolt signal of ORP in the anoxic moving bed biofilm reactor 3 in real time at a high-frequency sampling rate of 1Hz. Given the low water temperature and high viscosity of the mixed liquor in high-altitude regions, the sensor probe is prone to high-frequency noise. Therefore, the system sets a 5-second time sliding window and uses a 5-point moving average filtering method to process the raw data, obtaining a smoothed signal ORPf(t). This step effectively eliminates random errors caused by electrode polarization or fluid disturbances, while retaining the low-frequency trend signal that reflects the essence of the denitrification biochemical reaction.

[0061] Subsequently, the system enters the core derivative calculation and logical judgment stage. The PLC controller 12 performs a real-time differential operation once per second to calculate the first derivative of the smoothed signal. and second derivative The first derivative characterizes the rate of change of ORP, while the second derivative characterizes the increasing or decreasing trend of this rate of change. The system has a preset negative extreme value threshold. The value is -2.0 mV / s (which can be adjusted within the range of -1.5 mV / s to -3.0 mV / s depending on the water quality), serving as an "activation switch" to trigger denitrification recognition.

[0062] The determination of the denitrification endpoint employs a composite logic combining characteristic A and characteristic B in series to ensure accuracy. When the system continuously monitors... ≤ 2.0 mV / s indicates that the denitrification reaction is underway and the rate is accelerating; based on this, the system tracks in real time. The morphology, when first detected When a negative value crosses zero and becomes positive, it signifies that the increasing trend of the denitrification rate begins to weaken, indicating that the reaction has reached its "inflection point." To prevent false inflection points caused by signal fluctuations, the system incorporates a 3-point confirmation mechanism (N=3), requiring... The denitrification endpoint is finally confirmed only after the sample size remains non-negative for three consecutive sampling periods following the zero-crossing point. At this point, the PLC controller 12 immediately sends a stop signal to the carbon source metering pump 8. This control logic based on morphological recognition, compared to the traditional absolute threshold method, can predict the reaction endpoint in advance and minimize the over-addition of carbon source under low-temperature conditions, demonstrating the deep coupling between the algorithm and the process.

[0063] Example 3: This embodiment addresses the technical challenge of signal distortion caused by icing and scaling of the ORP sensor 10 in high-altitude and cold regions by constructing a multi-dimensional signal confidence evaluation system. The PLC controller 12 continuously monitors the statistical characteristics of the filtered ORP signal. When any of the following preset conditions are met, the sensor is deemed to have failed and mode switching is triggered: The first dimension is signal freeze determination, where the system calculates the variance of the ORP signal using a 60-second time window. When the variance of 3 consecutive windows When the value is ≤0.5, it indicates that the signal fluctuation is extremely small, which can be determined as "signal freezing" caused by the probe being covered by ice crystals or circuit failure; the second dimension is the hardware transition judgment, when the first derivative | When |≥10mV / s, the signal is determined to have a non-physical abrupt change, usually caused by loose wiring or electromagnetic interference; the third dimension is the dynamic response lag determination. Within a long period of 30 minutes, if the cumulative change of the filtered ORP signal ΔORP≤5mV, and the change in the influent flow rate exceeds 20% or the change in the carbon source metering pump frequency exceeds 30% during the same period, it is confirmed that the sensor is extremely insensitive to changes in operating conditions and has a serious response lag.

[0064] Once a sensor failure is detected, the dual-mode logic switching unit immediately cuts off the unreliable ORP feedback loop and seamlessly switches to the feedforward emergency mode. In this mode, the system abandons its dependence on the reaction end signal and instead drives the carbon source metering pump 8 in an open-loop feedforward manner according to the real-time flow rate Q (m³ / h) collected by the influent flow meter 11, using the formula M=Q×K. The carbon source equivalent constant K is not determined empirically but based on rigorous stoichiometric calculations: taking a 20% sodium acetate solution as an example, its COD equivalent is approximately 0.16 kg COD / L; according to denitrification theory, removing 1 g of nitrate nitrogen requires approximately 2.86 g of COD; if the target total nitrogen removal is 15 mg / L, then the required volume of 20% sodium acetate solution per cubic meter of wastewater is 0.27 L. Considering factors such as reduced microbial metabolic rate and decreased mixing mass transfer efficiency in cold environments, a safety factor of approximately 1.85 is introduced for correction, ultimately determining K=0.5 L / m³ in this embodiment. 3 As a preset value, this design ensures that even in extreme conditions where the sensor completely fails, the system can still maintain basic denitrification functions based on the influent load and simultaneously send alarm signals to the central control room until the signal returns to normal after manual intervention.

[0065] Compared with the prior art, the embodiments of this application have the following beneficial effects: First, this solution utilizes the bio-reaction heat carried by the internal reflux fluid for passive heating of the inner pipe, completely eliminating the reliance on high-energy-consuming electric heating tape and significantly reducing the operating cost of skid-mounted equipment. Simultaneously, by adding a manual anti-freeze purging valve to the carbon source pipeline, compressed air can be connected during shutdown to completely purge residual fluid, physically eliminating the risk of freezing and blockage in small-diameter pipelines in extremely cold environments.

[0066] Secondly, the carbon source, preheated by the internal reflux liquid within the casing, reduces local temperature disturbances caused by the direct entry of the low-temperature carbon source into the reaction tank, thus facilitating stable addition of the carbon source under low-temperature conditions. Combined with the submerged jet design at the end of the outer pipe, the reflux liquid jet promotes rapid dispersion of the carbon source, reducing local carbon source concentration and mitigating the local impact of high-concentration carbon sources on the MBBR packing biofilm. This also reduces the risk of excessive local proliferation of heterotrophic bacteria and biofilm clumping and detachment.

[0067] Third, the system employs a joint criterion of the first and second derivatives of the ORP signal to identify the denitrification endpoint. High-frequency noise is suppressed through moving average filtering, and the derivative characteristics of the ORP signal are utilized to reduce the impact of constant bias and slow baseline drift on feature recognition. Compared to the traditional absolute threshold method, this approach exhibits stronger anti-interference capabilities. Combined with a sensor anomaly diagnosis mechanism based on variance analysis, the system can switch to flow feedforward mode when the probe signal is abnormal, improving the continuity and stability of system operation in cold, unattended scenarios.

[0068] Fourth, this solution achieves deep synergy between structure and control: the internal reflux liquid serves as both a heat source and a dilution carrier, while the inlet water temperature maintained by the heat tracing of the sleeve indirectly reduces the risk of icing of the ORP probe, ensuring the authenticity of the feedback signal.

[0069] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A wastewater treatment device for preventing carbon blockage and release, characterized in that, It includes an internal reflux heat-tracing carbon release sleeve assembly, a skid-mounted insulated box (1), and a pretreatment unit (2), an anoxic moving bed biofilm reactor (3), an aerobic moving bed biofilm reactor (4), and a solid-liquid separation unit (5) arranged sequentially inside the box. An internal reflux pump (16) is provided between the aerobic moving bed biofilm reactor (4) and the anoxic moving bed biofilm reactor (3). The container is also equipped with a carbon source storage tank (7) and a carbon source metering pump (8). The internal reflux heat tracing carbon release sleeve assembly includes an outer tube (15) and an inner tube (13) coaxially inserted inside the outer tube. The inlet end of the outer tube (15) is connected to the outlet of the internal reflux pump (16), and the outlet end of the outer tube (15) extends below the designed liquid level of the anoxic moving bed biofilm reactor (3). The inlet end of the inner tube (13) is connected to the outlet of the carbon source metering pump (8), and the outlet end of the inner tube (13) is located inside the outlet end of the outer tube (15), and the outlet of the inner tube and the outlet of the outer tube are arranged coaxially. The carbon source is discharged into the reflux liquid in the outer tube (15) through the inner tube (13) for heat exchange and mixing.

2. The carbon release prevention and control equipment as described in claim 1, characterized in that, The liquid outlet end of the inner tube (13) is fitted with a duckbill check valve (17), which is made of low-temperature resistant special rubber or polytetrafluoroethylene.

3. The carbon release prevention and control equipment as described in claim 1, characterized in that, A three-way node is provided between the liquid inlet end of the inner tube (13) and the outlet pipe of the carbon source metering pump (8). A manual antifreeze purging valve (14) is connected to the bypass of the three-way node. The manual antifreeze purging valve (14) is connected to an external compressed air source for purging residual carbon source when the equipment is shut down.

4. The carbon release prevention and control equipment as described in claim 1, characterized in that, The ratio of the length L through which the inner tube (13) passes inside the outer tube (15) to the inner diameter D of the outer tube satisfies L / D≥30.

5. The carbon release prevention and control equipment as described in claim 1, characterized in that, Multiple centering supports (18) are provided axially along the outer wall of the inner tube (13). The centering supports (18) are used to fix the inner tube (13) on the central axis of the outer tube (15). A sealing structure (19) is provided at the joint entrance of the outer tube (15) and the inner tube (13) to prevent the backflow liquid in the outer tube from leaking along the outer wall of the inner tube.

6. A dual-modal adaptive control system based on the carbon blocking and release equipment according to any one of claims 1 to 5, characterized in that, It includes a PLC controller (12), an influent flow meter (11) that is connected to the PLC controller (12) in communication, an oxidation-reduction potential sensor (10) and a carbon source metering pump (8) installed in the anoxic moving bed biofilm reactor (3). The PLC controller (12) is internally configured with a signal filtering calculation unit and a dual-mode logic switching unit. The signal filtering calculation unit is used to preprocess the redox potential signal, and the dual-mode logic switching unit is used to switch between the normal closed-loop mode and the feedforward emergency mode according to the signal quality.

7. A dual-modal adaptive control method applied to the dual-modal adaptive control system of claim 6, characterized in that, include: Under normal closed-loop mode, the signal filtering calculation unit performs smoothing filtering on the redox potential signal within a set sliding time window and continuously calculates the first derivative of the filtered signal. and second derivative ; When determining the first derivative If the second derivative is detected for the first time within a continuous sampling period after the value falls below the preset negative extreme value threshold. When a value changes from negative to positive and remains positive or zero for N consecutive sampling points after crossing zero, the inflection point of denitrification is determined to have been reached, where N≥2; The PLC controller sends a signal to the carbon source metering pump to reduce the frequency or stop the pump.

8. The dual-modal control method as described in claim 7, characterized in that, Dual-modal control methods also include: When the signal filtering and calculation unit determines that any preset condition is met, the redox potential sensor is deemed to be faulty. The redox potential feedback loop is cut off by the dual-mode logic switching unit, and the system switches to feedforward emergency mode. In the feedforward emergency mode, the PLC controller drives the carbon source metering pump to add carbon source by multiplying the real-time flow rate Q collected by the inlet flow meter by the preset carbon source equivalent constant K in an open-loop feedforward manner. The preset conditions include: The variance of the redox potential signal within the sliding time window is lower than the set distortion judgment threshold; The absolute value of the first derivative exceeds the hardware jump threshold; Within the set long-term window, the cumulative change in the filtered oxidation-reduction potential signal is lower than the minimum threshold, and the change in the influent flow rate or the frequency of the carbon source metering pump exceeds the set value.

9. The dual-modal control method as described in claim 8, characterized in that, The carbon source equivalent constant K is determined by calculating the equivalent of the carbon source's chemical oxygen demand (COD) and the theoretical carbon requirement for denitrification, and then correcting it with a safety factor.

10. The dual-modal control method as described in claim 7, characterized in that, The duration of the sliding time window is 5 seconds, and a smooth signal is obtained by using a 5-point moving average filtering method; The preset negative extreme value threshold range is -1.5mV / s to 3.0mV / s; N takes the value of 3 in N consecutive sampling points.

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