Device and method for improving autotrophic denitrification performance of MABR reactor

Abstract

This invention relates to the field of wastewater biological treatment technology, specifically to a device and method for improving the autotrophic denitrification performance of a MABR reactor. It employs a composite membrane module combining a curtain-type silica gel filament membrane with excellent oxygen permeability with a spatial three-dimensional mesh packing material that facilitates the attachment of anaerobic ammonia-oxidizing bacteria, thereby coupling part of the nitrification reaction with the anaerobic ammonia oxidation reaction. Through the circulating reaction zone and membrane reaction zone within the reactor, nitrate nitrogen generated by anaerobic ammonia oxidation and excess nitrite nitrogen during instability adjustment are circulated and removed, thus improving the total nitrogen removal efficiency of the reactor. By adding appropriate amounts of sodium nitrite solution at appropriate times, the free nitrite concentration in the reactor mixture is increased. Simultaneously, the intermittent aeration ratio of the MABR is controlled to achieve synergistic inhibition of nitrite-oxidizing bacteria activity by low dissolved oxygen and high free nitrite, allowing the unstable short-range nitrification reaction to recover and improving the autotrophic denitrification performance of the reactor.

Description

Technical Field

[0001] This invention relates to the field of wastewater biological treatment technology, specifically to an apparatus and method for improving the autotrophic denitrification performance of a MABR reactor. Background Technology

[0002] The membrane aerated biofilm reactor (MABR) is a type of membrane-carried biofilm reactor that combines the features of traditional biofilm technology and gas separation membrane technology. Its membrane module has the functions of efficient oxygenation and microbial attachment carrier. Compared with the traditional activated sludge process and biofilm process, this process has significant advantages in terms of operating energy consumption and denitrification performance, and is a wastewater treatment technology with great development prospects.

[0003] The MABR process has unique technical characteristics. First, it uses a non-porous oxygen-permeable membrane, where oxygen is transferred to the attached biofilm in molecular form. This bubble-free aeration mode gives it extremely high oxygen mass transfer efficiency. Second, the biofilm easily attaches and grows on the surface of the MABR membrane fibers, and the anisotropic mass transfer of oxygen and pollutants within it creates a distinct stratified microbial community, forming multiple functional zones from the inside out, including aerobic, anoxic, and anaerobic zones. This allows for the efficient removal of organic matter, ammonia nitrogen, and total nitrogen in a single reactor. Third, it has high energy efficiency and permeability. The extremely high oxygen transfer efficiency of the oxygen membrane makes the aeration energy consumption required by this process significantly lower than that of the traditional activated sludge process, thus reducing operating costs. Studies have shown that the MABR process can reduce operating energy consumption by 40% to 80% compared to the traditional activated sludge process. In addition, the electron donors and acceptors in the MABR biofilm have the characteristic of "reverse diffusion", which makes it easy to control the nitrification reaction and makes it feasible to combine it with autotrophic denitrification reactions such as anaerobic ammonium oxidation. Therefore, the MABR technology has natural applicability in simultaneous nitrification and denitrification, short-cut nitrification and denitrification, and short-cut nitrification-anaerobic ammonium oxidation autotrophic denitrification.

[0004] Autotrophic nitrogen removal technology based on anaerobic ammonia oxidation (Anammox) boasts advantages such as high nitrogen removal efficiency, 50-60% lower energy consumption compared to traditional processes, no need for organic carbon sources, and minimal residual sludge production, making it a promising technology with broad development prospects. This autotrophic nitrogen removal technology is a biological oxidation-reduction process that uses ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor, under the action of anaerobic ammonia-oxidizing bacteria, to convert ammonia nitrogen and nitrite nitrogen into nitrogen gas. In practical applications, partial short-cut nitrification is typically coupled with anaerobic ammonia oxidation, where approximately half of the ammonia nitrogen in the wastewater is nitrified into nitrite nitrogen, which then undergoes anaerobic ammonia oxidation with the remaining ammonia nitrogen to complete the removal of total nitrogen. The heterogeneous mass transfer biofilm in the MABR process exhibits both low organic matter concentration and high dissolved oxygen conditions on its inner side, which favors the growth of aerobic ammonia-oxidizing bacteria (AOB). Conversely, when the oxygen supply is adjusted to create an anoxic environment in the bulk liquid phase, the outer side of the biofilm experiences high organic matter concentration and low dissolved oxygen conditions, which favors the growth of anaerobic ammonia-oxidizing bacteria and heterotrophic nitrifying bacteria. This unique microbial stratification effectively inhibits the activity of nitrite-oxidizing bacteria (NOB), facilitating short-cut nitrification in the MABR reactor. This, in turn, couples nitrite oxidation and anaerobic ammonia oxidation within the same reactor, forming a single-stage autotrophic nitrogen removal MABR process.

[0005] The key to achieving efficient autotrophic denitrification in a MABR reactor lies in providing stable nitrite nitrogen through partial short-cut nitrification and effectively enriching and retaining anaerobic ammonia-oxidizing bacteria within the reactor. Short-cut nitrification primarily utilizes the differences in physiological characteristics and kinetics between ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), and their varying adaptability to different environmental factors. By controlling the reaction conditions within a range suitable for AOB growth while inhibiting NOB activity, NOB is continuously eliminated from the reactor, achieving the nitrification process. Currently, commonly used short-cut nitrification control factors mainly include: temperature, dissolved oxygen (DO), pH, sludge time (SRT), free ammonia (FA), free nitrite (FNA), and toxicity inhibitors, etc. Dissolved oxygen (DO) is a crucial factor in distinguishing between ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). This is because AOB has a higher affinity for oxygen than NOB; therefore, lower dissolved oxygen levels inhibit NOB activity while leaving AOB unaffected. Dissolved oxygen can be controlled primarily through aeration rate and intermittent aeration patterns. AOB is more temperature-sensitive than NOB; increasing temperature promotes AOB proliferation and eliminates NOB, especially at temperatures exceeding 30°C. Accumulation of nitrite nitrogen: The inhibitory concentration of free ammonia (FA) on nitrite oxidizing bacteria (NOB) is much lower than that on ammonia oxidizing bacteria (AOB). Higher levels of free ammonia (FA) are beneficial for inhibiting the activity of nitrite oxidizing bacteria (NOB), thereby leading to the accumulation of nitrite nitrogen. Usually, the free ammonia control strategy is used in conjunction with higher pH conditions. Under alkaline conditions, higher concentrations of free ammonia are easily generated in the reactor. The inhibitory concentration of free nitrite (FNA) on ammonia oxidizing bacteria (AOB) is tens of times higher than that on nitrite oxidizing bacteria (NOB). Utilizing free nitrite (FNA) generated under lower pH conditions can inhibit nitrite oxidizing bacteria (NOB) and lead to the accumulation of nitrite nitrogen. To increase the enrichment and retention of anaerobic ammonia oxidizing bacteria in the reactor, the main methods include inoculating the reactor with flocculent sludge or granular sludge with a high abundance of anaerobic ammonia oxidizing bacteria, adding packing material in the reactor that is easy for anaerobic ammonia oxidizing bacteria to attach and grow, and controlling suitable growth conditions for anaerobic ammonia oxidizing bacteria (dissolved oxygen, temperature, pH, alkalinity, nitrogen load).

[0006] Due to the growth characteristics of nitrite-oxidizing bacteria (NOB), controlling the above-mentioned regulatory factors within the inhibitory range can rapidly inhibit their growth, leading to the accumulation of nitrite nitrogen in the reactor and achieving short-cut nitrification. However, the regulatory measures directly affect the actual operation of the autotrophic denitrification reactor, especially for special reactors like MABRs. During long-term operation of the reactor, particularly when using a single inhibitory factor control strategy, nitrite-oxidizing bacteria (NOB) gradually develop tolerance to the above-mentioned inhibitory factors. This tolerance becomes more pronounced, leading to the continuous proliferation of nitrite-oxidizing bacteria (NOB) in the reactor. This causes nitrite nitrogen to be oxidized to nitrate nitrogen, disrupting the short-cut nitrification state. Consequently, the anaerobic ammonia oxidation reaction cannot obtain sufficient nitrite nitrogen, resulting in a decrease in reaction efficiency. The autotrophic denitrification reactor then becomes unstable, and its denitrification performance is significantly reduced. Meanwhile, MABR biofilms are long-sludge-age biofilm systems, making it impossible to directly rely on microbial growth kinetics to wash nitrite-oxidizing bacteria (NOB) out of the reactor or to exert long-term inhibition on them. Therefore, achieving long-term stable short-cut nitrification in an MABR reactor presents significant challenges. Current solutions employ a multi-factor combined control strategy to maintain long-term inhibition or elimination of NOB, specifically using integrated control strategies such as low dissolved oxygen and high free ammonia (FA), low dissolved oxygen and high free nitrite (FNA), and high temperature and low dissolved oxygen with a short sludge age. However, in practical engineering applications, some problems still exist. For autotrophic denitrification reactors with high concentrations of ammonia-containing wastewater, a comprehensive control strategy can be implemented to fully utilize the high concentration of ammonia nitrogen to generate sufficient free ammonia (FA) or free nitrite (FNA) to effectively inhibit nitrite-oxidizing bacteria (NOB), with obvious regulation effects and relatively stable nitrification reaction. However, when using mainstream autotrophic denitrification treatment for wastewater with medium to low concentrations of ammonia nitrogen or domestic sewage, it is difficult to use free ammonia (FA) or free nitrite (FNA) in combination with low concentrations of dissolved oxygen, making the insufficient stability of reactor operation more obvious.

[0007] Precise control of free nitrite concentration is difficult when inhibiting nitrite-oxidizing bacteria. Free nitrite concentrations exceeding 0.2 mg / L will inhibit all nitrifying bacteria, including AOB and NOB. Furthermore, the optimal pH for AOB is 8-9, while for nitrite-oxidizing bacteria it is 6.5-7.5. The synergistic inhibition of nitrite-oxidizing bacteria (NOB) by low dissolved oxygen and free nitrite (FNA) requires a lower pH (typically 6.0-6.5) and a higher concentration of nitrite nitrogen, conditions that are difficult to meet in actual wastewater treatment processes. Maintaining a low pH requires the artificial addition of large amounts of acid, which severely impacts both AOB and nitrite-oxidizing bacteria, and also affects the survival of most activated sludge microorganisms. Furthermore, MABR reactors differ significantly from traditional biofilm reactors. The presence of heterogeneous mass transfer in MABR biofilms prevents nitrite-oxidizing bacteria from being completely eliminated from the reactor as in traditional biofilms. Nitrite-oxidizing and ammonia-oxidizing bacteria coexist in the MABR biofilm. Therefore, the sodium nitrite solution addition strategy and reactor stability control employed in this invention require dynamic adjustments and implementation during continuous operation. It is not possible to achieve a stable short-cut nitrification process and a stable autotrophic denitrification process by simply suppressing or killing nitrite-oxidizing bacteria with high concentrations of free nitrite at the beginning of reactor operation. Therefore, improving the stability of the nitrite process during reactor operation to enhance the performance of autotrophic denitrification reactors remains a pressing problem that needs to be solved in current research and application.

[0008] In published invention patent applications, methods such as adding hydroxylamine and continuously alternating addition of hydroxylamine and hydrazine were used to inhibit the activity of nitrite-oxidizing bacteria (NOB) to enhance autotrophic denitrification. The application states that hydroxylamine, as an intermediate product of nitrification and anaerobic ammonium oxidation, can enhance the activity of ammonia-oxidizing bacteria (AOB) and can affect the synthesis of nitrite oxidoreductase, thereby inhibiting NOB activity. Hydrazine, as an intermediate product of anaerobic ammonium oxidation, while enhancing the activity of anaerobic ammonium oxidizing bacteria (AnAOB), has a strong inhibitory effect on the *Nitrobacter* genus of nitrite-oxidizing bacteria (NOB). The control strategy of adding these two substances has only been carried out in small-scale laboratory autotrophic denitrification studies and has not yet been verified or applied in actual engineering. The main problems are: ① Long-term addition of hydroxylamine alone may lead to increased NOB tolerance, easily causing NOB species migration and resulting in the recovery of NOB activity. ② Hydroxylamine is unstable and highly hygroscopic. It rapidly decomposes upon absorbing water vapor and carbon dioxide at room temperature, and explodes violently upon heating. It is a potential mutagen and also highly toxic, posing a significant risk in practical applications. ③ There is a lack of systematic studies on the effects of hydrazine on all major bacteria involved in denitrification. Even slightly higher concentrations can slow down the denitrification process. ④ Hydrazine is a Group 2A carcinogen with high toxicity. Prolonged exposure to air or short-term exposure to high temperatures can cause it to decompose explosively. It also has strong hygroscopic properties, making its engineering applications highly dangerous.

[0009] There are also methods to regulate reactor instability through lateral inhibition, but these also have drawbacks: ① Existing methods for determining MABR reactor instability are too simplistic and cannot meet the requirements for determining stability during actual operation. This is because MABR reactors contain short-cut nitrification, anaerobic ammonium oxidation, and heterotrophic denitrification or short-cut heterotrophic denitrification reactions due to the presence of organic matter in the influent. Simultaneously, there are numerous endogenous denitrification reactions that utilize the organic matter produced by bacterial death. This results in a wide range of variations in the nitrate nitrogen ratio in the effluent of the autotrophic denitrification reactor. In particular, heterotrophic denitrification significantly reduces nitrate nitrogen in the effluent of the integrated reactor, rendering the single method of determining the nitrite nitrogen formation ratio ineffective. ② Lateral inhibition also introduces a significant lag in the main process of the MABR autotrophic denitrification reaction. For main process reactors that have already experienced excessive NOB proliferation, the amount of lateral inhibition is insufficient to quickly and promptly change the instability state, making the entire autotrophic denitrification reactor's recovery process quite lengthy. ③ The side-by-side inhibition device can only perform side-by-side inhibition operation on suspended sludge in the integrated autotrophic denitrification device, but it cannot inhibit the proliferation of NOB in the biofilm attached to the packing material in the integrated autotrophic denitrification device, thus reducing the actual efficiency of the device.

[0010] The existing MABR reactors used for autotrophic biological nitrogen removal have the following drawbacks: ① The MABR membrane module and the biofilm filter, contact oxidation, and other modules are arranged in a simple top-to-bottom configuration within the same reactor. During long-term operation, there is a risk of the combined drawbacks of both types of treatment modules, resulting in severe biofilm clogging or membrane floc fouling problems. Furthermore, backwashing, maintenance, and repair of the membrane module are extremely inconvenient. ② Multiple MABR reactors connected in series form a multi-stage treatment process, resulting in a complex structure, increased infrastructure investment, and more complex operation and management. The process parameters of each reactor need to be controlled individually, especially in the first-stage reactor, which requires high alkalinity for buffering during nitrification or nitrite formation, reducing operational stability. Summary of the Invention

[0011] To improve the stability and performance of the autotrophic denitrification process in a MABR reactor, this invention proposes a device and method for enhancing the autotrophic denitrification performance of a MABR reactor. A composite membrane module combining a curtain-type silica gel filament membrane with excellent oxygen permeability and a three-dimensional mesh packing material that facilitates the attachment of anaerobic ammonia-oxidizing bacteria is employed to couple the partial nitrification reaction with the anaerobic ammonia oxidation reaction. By adding appropriate amounts of sodium nitrite solution at appropriate times, the concentration of free nitrite (FNA) in the reactor mixture is increased. During the process where nitrite-oxidizing bacteria (NOB) continuously proliferate in the MABR biofilm, causing short-cut nitrification to gradually degenerate into complete nitrification, the activity of nitrite-oxidizing bacteria is enhanced. The inhibitory effect of nitrite-oxidizing bacteria (NOB) is achieved by simultaneously regulating the intermittent ratio of MABR intermittent aeration. This synergistic inhibition of NOB activity by low dissolved oxygen (DO) and high free nitrite (FNA) allows the unstable short-cut nitrification reaction to recover, and some ammonia nitrogen is converted into nitrite nitrogen as needed, thereby meeting the requirements of anaerobic ammonia oxidation reaction and improving the autotrophic nitrogen removal performance of the reactor. Furthermore, through the circulating reaction zone and membrane reaction zone set inside the single MABR reactor, the nitrate nitrogen generated by anaerobic ammonia oxidation and the excess nitrite nitrogen during the instability adjustment period are circulated and removed, thereby improving the total nitrogen removal efficiency of the reactor.

[0012] This invention provides an apparatus for improving the autotrophic denitrification performance of a MABR reactor to solve the above-mentioned technical problems, comprising:

[0013] The reaction tank is internally divided into a circulating reaction zone and a membrane reaction zone with the bottom connected. The inlet pipe is connected to the circulating reaction zone, and the outlet pipe is connected to the membrane reaction zone. The circulating reaction zone is equipped with a stirring and circulation system, and the membrane reaction zone is equipped with a water distribution perforated plate. Below the water distribution perforated plate is a sludge zone, and above it are multiple sets of MABR membrane modules.

[0014] The reagent dosing system includes multiple sets of membrane zone dosing components located between the MABR membrane module and the water distribution perforated plate and corresponding to each set of the MABR membrane module;

[0015] The air supply system is used to aerate each of the MABR membrane modules;

[0016] The mixed liquor reflux system is used to return the mixed liquor in the membrane reaction zone to the circulating reaction zone;

[0017] The sludge return system is used to return sludge from the sludge zone to the recycling reaction zone;

[0018] An air agitation system is used to flush each of the MABR membrane modules with airflow.

[0019] An online monitoring instrument system is used to monitor the water quality indicators in the membrane reaction zone and the influent water quality indicators in real time, including a PLC control cabinet that is connected to the reagent dosing system and the gas supply system.

[0020] Furthermore, the MABR membrane module includes, from the outside to the inside, an outer frame of the membrane module, a three-dimensional mesh packing layer, an inner frame of the membrane module, and a curtain-type membrane fiber element. The curtain-type membrane fiber element includes multiple horizontally uniformly distributed filamentous silicone membranes and an air inlet vertical pipe and an exhaust vertical pipe respectively connected to both ends of the filamentous silicone membranes on both sides. The air inlet vertical pipe is connected to the aeration pipe of the air supply system, and the exhaust vertical pipe is connected to the exhaust pipe of the air supply system.

[0021] Furthermore, the membrane zone dosing assembly includes a dosing main pipe with multiple parallel perforated dosing pipes. The multiple dosing main pipes extend to the outside of the reaction tank and are equipped with dosing main pipe valves and connected to a dosing distribution pipe. The dosing distribution pipe is connected to the dosing pipe, and the dosing pipe is connected to a nitrite storage tank. The dosing pipe is equipped with a valve, a nitrite flow meter, and a nitrite metering pump.

[0022] Furthermore, the mixed liquor reflux system includes a mixed liquor reflux pipe connected to the upper part of the membrane reaction zone, and the sludge reflux system includes a sludge reflux pipe connected to the sludge zone. The sludge reflux pipe is equipped with a sludge discharge pipe. The mixed liquor reflux pipe and the sludge reflux pipe are connected to the circulating reaction zone through a reflux trunk pipe. The reflux trunk pipe is equipped with a heat exchange system.

[0023] The air mixing system includes an air mixing component located in the sludge zone corresponding to each MABR membrane module, and the air mixing component is connected to the corresponding air mixing branch pipe.

[0024] The stirring and circulating system includes a circulating guide tube located in the circulating reaction zone, and an upflow stirrer is installed inside the circulating guide tube.

[0025] Furthermore, the online monitoring instrument system includes an online dissolved oxygen meter, an online ORP meter, an online ammonia nitrogen meter, an online nitrate nitrogen meter, an online nitrite nitrogen meter, and an online pH meter for the membrane reaction zone, all located within the membrane reaction zone and connected to the PLC control cabinet via secondary monitoring instruments for the membrane reaction zone. It also includes an online pH meter and an online ammonia nitrogen meter for the inlet water, both located on the inlet water pipe and connected to the PLC control cabinet via secondary monitoring instruments for the inlet water.

[0026] This invention also provides a method for improving the autotrophic denitrification performance of a MABR reactor, using the aforementioned apparatus for improving the autotrophic denitrification performance of a MABR reactor, the steps of which are as follows:

[0027] S001. Inoculate and attach biofilm in the MABR reactor, and ensure that the autotrophic denitrification of the MABR reactor operates normally;

[0028] S002. Establish the baseline values ​​of each data during normal operation of the autotrophic denitrification process of the MABR reactor and store them in the PLC controller. Each data includes: dissolved oxygen, pH value, redox potential, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and temperature in the membrane reaction zone (4); and ammonia nitrogen, pH value and temperature in the influent.

[0029] S003. Establish a database for determining the stability decline of the autotrophic denitrification process in the MABR reactor: Based on the changing trends of water quality indicators in the autotrophic denitrification process of the MABR reactor, list the main causes of instability in the autotrophic denitrification process of the MABR reactor.

[0030] S004. Continuously collect online monitoring data of the autotrophic denitrification process of the MABR reactor and input them into the PLC controller. Compare each online monitoring data with the baseline value of each data and determine the cause of the instability of the autotrophic denitrification process of the MABR reactor based on the data trend in the judgment database.

[0031] S005. Based on the reasons for the instability of autotrophic denitrification in the MABR reactor in step S004, make corresponding adjustments.

[0032] Furthermore, in step S005, the reason for the autotrophic denitrification instability of the MABR reactor is the increased activity of nitrite-oxidizing bacteria within the MABR biofilm, indicating a tendency towards complete nitrification.

[0033] (1) Turn on the reagent dosing system, add sodium nitrite solution into the membrane reaction zone, increase the intermittent aeration ratio of the gas supply system and maintain it for a period of time;

[0034] (2) When the nitrate nitrogen concentration decreases to the baseline value, reduce the amount of sodium nitrite added and maintain it for a period of time;

[0035] (3) When the pH value in the membrane reaction zone recovers to above 7.0 and the redox potential recovers to 50~100mV, stop adding sodium nitrite and restore the intermittent aeration ratio to the normal operating value.

[0036] Furthermore, in step S005, the reason for the instability of autotrophic denitrification in the MABR reactor is that when the short-cut nitrification reaction of the MABR biofilm is excessive or insufficient, it is regulated by intermittent aeration mode and influent nitrogen load:

[0037] a. When the short-range nitrification reaction of the MABR biofilm is excessive:

[0038] Analyze the intermittent aeration ratio and influent nitrogen load before and after the instability of the MABR autotrophic denitrification reactor; if the influent nitrogen load does not change significantly, increase the intermittent aeration ratio to 2.0~3.0; if the influent nitrogen load decreases, restore the influent nitrogen load; if the influent nitrogen load cannot be restored in the short term, increase the intermittent aeration ratio to 2.0~4.0, while reducing the aeration time to 15min~20min.

[0039] b. When the short-range nitrification reaction of the MABR biofilm is insufficient:

[0040] Analyze the intermittent aeration ratio and influent nitrogen load before and after the instability of the MABR autotrophic denitrification reactor; if the influent nitrogen load does not change significantly, reduce the intermittent aeration ratio by 0.5~1.0; if the influent nitrogen load increases, restore the influent nitrogen load; if the influent nitrogen load cannot be restored in the short term, reduce the intermittent aeration ratio by 0.5~1.0, and increase the aeration time by 30min~60min.

[0041] Furthermore, in step S001, the method for establishing the autotrophic denitrification process in the MABR reactor is as follows:

[0042] S0011, Nitrifying biofilm attachment:

[0043] (1) Inoculate aerobic activated sludge into the circulating reaction zone and continuously turn on the stirring circulation system, mixed liquor return system, and air supply system; intermittently add water and intermittently turn on the air stirring system; turn off the sludge return system and heat exchange system;

[0044] (2) When the pH value in the membrane reaction zone drops below 6.5~7.0 and the ammonia nitrogen concentration is 5%~10% lower than the influent ammonia nitrogen concentration, gradually increase the proportion of influent time;

[0045] (3) When the continuous influent mode is achieved and the pH value and ammonia nitrogen concentration of the effluent decrease significantly, the nitrification biofilm formation is completed;

[0046] S0012. Establishment of the short-cut nitrification process:

[0047] (1) Continuously turn on the mixed liquor return system and sludge return system, adjust the air supply system to intermittent aeration with an intermittent aeration ratio of 1.0~1.5, and reduce the aeration pressure and aeration flow rate at the same time;

[0048] (2) Turn on the reagent dosing system and continuously add sodium nitrite solution into the membrane reaction zone;

[0049] (3) Turn on the heat exchange system and control the temperature of the mixed liquid to 25℃~30℃;

[0050] (4) When the nitrate nitrogen value in the membrane reaction zone drops to 80%~90% of the nitrate nitrogen value when the nitrification biofilm is attached, stop adding sodium nitrite solution, keep the heat exchange system running, continuously feed water and aerate, and intermittently turn on the air stirring system, and then run continuously. When the ammonia nitrogen removal rate of the effluent from the membrane reaction zone is 92%~98% and the nitrite nitrogen accumulation rate reaches 85~95%, the short-cut nitrification process is established.

[0051] S0013. Start-up of the anaerobic ammonium oxidation autotrophic denitrification process:

[0052] (1) Adjust the short-cut nitration reaction in the MABR reactor to a partially short-cut nitration state;

[0053] (2) Increase the intermittent aeration ratio of the air supply system to 1.5~3.0, and further reduce the aeration pressure and aeration flow rate; control the ratio of residual ammonia nitrogen to nitrite nitrogen concentration in the effluent between 1:1 and 1:1.3;

[0054] (3) Open the sludge discharge pipe and close the sludge return system to discharge about 50% of the sludge in the sludge zone;

[0055] (4) Inoculate sludge containing anaerobic ammonia oxidizing bacteria into the circulating reaction zone, shut down the stirring and circulating system, continuously turn on the mixed liquor reflux system, air supply system and heat exchange system, and intermittently turn on the air stirring system;

[0056] (5) The dosing system is used in conjunction with the intermittent aeration mode. The dosing system is turned on during the last 20% to 30% of the time after aeration stops, and sodium nitrite solution is added to the membrane reaction zone.

[0057] (6) Continue to run until the pH value of the effluent rises to 7.2~7.7, the oxidation-reduction potential value drops to 50mV~100mV, the nitrate nitrogen concentration rises to 10%~15% of the influent ammonia nitrogen concentration, and the total nitrogen removal rate of the effluent reaches 70%~80%, then the anaerobic ammonia oxidation autotrophic denitrification process is started.

[0058] S0014. Establishment of a stable autotrophic denitrification process: Close the reagent dosing system, continuously turn on the sludge return system, mixed liquor return system and stirring circulation system, maintain intermittent aeration of the air supply system, and continue to operate until the total nitrogen removal rate of the effluent reaches 80~85%, the ammonia nitrogen removal rate exceeds 95%, the pH value is 7.0~8.0, and the oxidation-reduction potential is 50mV~100mV, thus completing the establishment of the autotrophic denitrification process in the MABR reactor.

[0059] Furthermore, in step S003, the database determination includes:

[0060]

[0061] The beneficial effects of using the present invention are as follows:

[0062] (1) This invention proposes a device to improve the autotrophic denitrification performance of MABR reactors for the efficient autotrophic biological denitrification treatment of medium and low concentration ammonia-containing wastewater or domestic sewage. By setting a double-layer frame in the MABR membrane module and embedding a three-dimensional mesh packing material, the attachment of autotrophic denitrifying bacteria such as anaerobic ammonia oxidizing bacteria is increased. A composite membrane module combining curtain-type filamentous silica membrane and three-dimensional mesh packing material is used to construct a system of coupled symbiosis of MABR short-cut nitrification biofilm, anaerobic ammonia oxidation biofilm, and heterotrophic denitrification biofilm. At the same time, different reaction zones such as circulation reaction zone and MABR reaction zone are set in a single reactor, thereby promoting the synergy and integration of multiple denitrification reactions such as short-cut nitrification and denitrification, anaerobic ammonia oxidation and heterotrophic denitrification in a single-stage reactor, improving the autotrophic denitrification efficiency of the reactor, and solving the shortcomings of existing MABR reactors used for autotrophic denitrification, such as the superposition of the disadvantages of the two processes when the MABR membrane module and the biofilm method are simply arranged in the same reactor, and the complexity of multi-stage MABR reactors in series operation.

[0063] (2) This invention proposes a method for establishing an autotrophic denitrification process in a MABR reactor. For nitrogen-containing industrial wastewater and domestic sewage with low carbon-to-nitrogen ratios, the autotrophic denitrification process in the MABR reactor can be established in steps, namely, the establishment of nitrifying biofilm, the establishment of short-cut nitrification, the start-up of anaerobic ammonia oxidation autotrophic denitrification, and the establishment of a stable autotrophic denitrification process. By controlling the low dissolved oxygen (DO) in the MABR reactor through intermittent aeration and adding sodium nitrite solution to generate a high concentration of free nitrite (FNA), a multi-factor synergistic inhibition of nitrite-oxidizing bacteria (NOB) is achieved, accelerating the establishment of the short-cut nitrification process in the MABR reactor. At the same time, by adding sodium nitrite solution and regulating the intermittent aeration mode, the start-up speed of the anaerobic ammonia oxidation autotrophic denitrification process and the establishment speed of the stable autotrophic denitrification process are improved. That is, the sodium nitrite solution addition strategy is different in the establishment of short-cut nitrification reaction, the establishment of anaerobic ammonia oxidation process, and the re-regulation process after reactor instability in the early stage of reactor operation. Furthermore, by adding sodium nitrite solution and using intermittent aeration, the drawback of poor persistence in inhibiting the activity of nitrite-oxidizing bacteria (NOB) by a single factor is overcome. At the same time, sodium nitrite is stable, relatively safe to operate, inexpensive and readily available, which makes the control strategy of this invention easier to implement in practice.

[0064] (3) This invention proposes a method for assessing the stability of autotrophic denitrification in a MABR reactor. By establishing a baseline value for the normal operation of the autotrophic denitrification process in the MABR reactor and a database for determining the stability decline of the autotrophic denitrification process, the continuously collected online monitoring data is compared with the baseline value of the reactor. Based on the trend in the database, the main causes of the instability of the autotrophic denitrification reaction are obtained. The method for determining the stability of the autotrophic denitrification reactor used in this invention is based on a large amount of historical operating data. It uses the changing trends of multiple parameters of the autotrophic denitrification reactor to determine the stability of the autotrophic denitrification reactor under complex operating conditions. The comprehensive determination method of the changing trends of multiple parameters can match the operating conditions of the MABE membrane module composed of high-efficiency oxygen transfer silica membrane filaments and spatial three-dimensional mesh packing in the MABR reactor. Among them, ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria, heterotrophic denitrifying bacteria and other organisms coexist and coexist, forming a dynamic and stable autotrophic denitrification stabilizer. The method for determining the instability of the reactor does not use a single value or a fixed value, and can obtain the accurate cause of the reactor's instability.

[0065] (4) This invention proposes a method to improve the stability and performance of autotrophic denitrification in MABR reactors. Different targeted strategies are adopted for dynamic regulation based on the different causes of instability in autotrophic denitrification reactions. The key to controlling instability in the short-cut nitrification process is the addition of sodium nitrite solution. This allows the reactor mixture to generate a sufficient concentration of free nitrite (FNA) at a relatively low pH. In this invention, sodium nitrite solution is continuously added during reactor operation, controlling the pH between 6.0 and 6.5. This pH range is the range of pH decrease achievable during complete nitrification, eliminating the need for artificial acid addition. Controlling the FNA concentration inhibits nitrite-oxidizing bacteria without excessively affecting ammonia-oxidizing bacteria. Furthermore, the online addition method directly influences the state of various microorganisms within the MABR reactor, particularly promptly addressing the excessive proliferation of nitrite-oxidizing bacteria without the lag of lateral inhibition. It also directly regulates suspended flocculent sludge, MABR biofilm growing on the MABR membrane filaments, and anaerobic biofilm attached to the three-dimensional mesh packing, thus promoting stable reactor operation. The addition of sodium nitrite solution, combined with the low dissolved oxygen resulting from intermittent aeration, inhibits nitrite-oxidizing bacteria (NOB) in the MABR biofilm, restoring the short-cut nitrification process and stabilizing the autotrophic denitrification reaction. The key to regulating the decline in anaerobic ammonia oxidizing bacteria activity is the periodic addition of sodium nitrite during reactor operation to stabilize the short-cut nitrification process. This also increases the substrate for the anaerobic ammonia oxidation reaction, stimulating the growth of anaerobic ammonia oxidizing bacteria, increasing their attachment and growth within the composite membrane module, and improving their retention.

[0066] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the device for improving the autotrophic denitrification performance of a MABR reactor according to the present invention;

[0068] Figure 2 This is a schematic diagram of the structure of the MABR membrane module of the present invention;

[0069] Figure 3 This is a schematic diagram of the membrane-area drug delivery assembly of the present invention.

[0070] In the attached diagram: 1—MABR reactor; 2—Circulating reaction zone; 3—Upper support beam of the guide tube; 4—Membrane reaction zone; 5—Separation wall; 6—Circulating guide tube; 7—Upflow agitator; 8—Lower support beam of the guide tube; 9—MABR membrane module; 10—Support beam; 11—Water passage; 12—Sludge zone; 13—Perforated water distribution plate; 14—Inlet main pipe; 15—Flow-through test tank; 16—Reactor inlet pipe; 17—Exhaust valve; 18—Online pH meter for inlet water; 19—Online ammonia nitrogen meter for inlet water; 20—Outlet pipe; 21—Air supply fan; 22—Air supply main pipe valve. ; 23—Air supply main pipe air flow meter; 24—Air supply main pipe; 25—Air supply branch pipe valve; 26—Air supply branch pipe air flow meter; 27—Air supply branch pipe pressure sensor; 28—Air supply branch pipe; 29—Exhaust branch pipe; 30—Exhaust branch pipe valve; 31—Exhaust main pipe; 32—Mixed liquid discharge pipe; 33—Mixed liquid return pump; 34—Mixed liquid return pipe valve; 35—Mixed liquid return pipe check valve; 36—Mixed liquid return flow meter; 37—Mixed liquid return pipe; 38—Return main pipe; 39—Heat exchange tank; 40—Heat exchange coil; 41—Electric heating tube; 4 2—Electric heating power supply; 43—Sludge return pump inlet pipe; 44—Sludge return pump; 45—Sludge discharge valve; 46—Sludge discharge pipe; 47—Sludge return valve; 48—Sludge return pipe check valve; 49—Sludge return flow meter; 50—Sludge return pipe; 51—Air agitator blower; 52—Air agitator main pipe; 53—Air agitator main pipe valve; 54—Air agitator main pipe pressure sensor; 55—Air agitator branch pipe air flow meter; 56—Air agitator branch pipe valve; 57—Air agitator branch pipe; 58—Air agitator assembly; 59—Air agitator perforated pipe. 60—Nitrite dosing pump outlet pipe; 61—Nitrite dosing flow meter; 62—Nitrite dosing metering pump; 63—Nitrite dosing pump inlet pipe; 64—Nitrite storage tank; 65—Membrane zone dosing assembly; 66—Online dissolved oxygen meter; 67—Online ORP meter; 68—Online ammonia nitrogen meter in membrane reaction zone; 69—Online nitrate nitrogen meter; 70—Online nitrite nitrogen meter; 71—Online pH meter in membrane reaction zone; 72—Secondary monitoring instruments in membrane reaction zone; 73—Secondary monitoring instruments for influent; 74—Online thermometer for heat exchange tank; 75—PLC control cabinet;

[0071] 901—Outer frame of membrane module; 902—Spatial three-dimensional mesh packing layer; 903—Inner frame of membrane module; 904—Curtain-type membrane fiber element; 905—Inlet riser of membrane fiber element; 906—Inlet pipe of membrane fiber element; 907—Exhaust riser of membrane fiber element; 908—Exhaust pipe of membrane fiber element;

[0072] 6501—Dosing distribution pipe; 6502—Dosing main pipe valve; 6503—Dosing main pipe; 6504—Dosing perforated pipe; 6505—Pool wall. Detailed Implementation

[0073] Referring to the accompanying drawings, specific embodiments of the present invention will be described in detail.

[0074] Reference Figures 1 to 3 This invention provides an embodiment of a device for improving the autotrophic denitrification performance of a MABR reactor.

[0075] A device for improving the autotrophic denitrification performance of a MABR reactor includes a reaction tank 1, a reagent dosing system, an air supply system, a mixed liquor reflux system, a sludge reflux system, an air mixing system, and an online monitoring instrument system.

[0076] The reaction tank 1 is a rectangular water tank, which can be made of reinforced concrete or steel, depending on the treatment scale. Internally, it is divided by a partition wall 5 into a bottom-connected circulating reaction zone 2 and a membrane reaction zone 4. A water passage 11 at the bottom of the partition wall 5 connects the bottoms of the circulating reaction zone 2 and the membrane reaction zone 4. The flow velocity of the mixed liquor at the water passage 11 is 0.3~0.6 m / s. The volume ratio of the circulating reaction zone 2 to the membrane reaction zone 4 is 1:4~1:5. The effective water depth of the reaction tank 1 is 3~5 m, and a protective barrier is installed at the top with a height of 0.5~0.8 m.

[0077] The inlet pipe 16 is connected to the circulating reaction zone 2, and the outlet pipe 20 is connected to the membrane reaction zone 4. The circulating reaction zone 2 is equipped with a stirring and circulating system, which includes a circulating guide cylinder 6 located within the circulating reaction zone 2. The circulating guide cylinder 6 is made of stainless steel (SS304) or polypropylene (PP) cylindrical material. The length of the circulating guide cylinder 6 is 2 / 3 to 3 / 4 of the effective water depth of the circulating reaction zone 2, and its diameter is 1 / 4 to 2 / 5 of the net width of the circulating reaction zone 2. The circulating guide cylinder 6 is vertically fixed to the center of the circulating reaction zone 2 by an upper support beam 3 and a lower support beam 8. The two support beams are stainless steel (SS304) cross-shaped steel beams, with both ends firmly fixed to the inner wall of the reaction tank 1 and the outer wall of the circulating guide cylinder 6, respectively. The circulating guide tube 6 is equipped with a flow-up agitator 7, which is used to lift the mixed liquid in the circulating guide tube 6, so that the flow direction of the mixed liquid inside the circulating guide tube 6 is from bottom to top, and the flow direction of the mixed liquid outside the circulating guide tube 6 is from top to bottom, thereby generating a circulating flow of the mixed liquid. The flow-up agitator 7 adopts frequency conversion control, and the speed can be adjusted according to process requirements to change the circulation ratio of the liquid inside and outside the guide tube. The agitator 7 has a hyperboloid shape, and the surface of the agitator is made of fiberglass (FRP) or stainless steel (SS304). The motor of the agitator is a frequency conversion motor, which is installed at the top of the circulating reaction zone 2. The water 14 of the MABR reactor enters from the top of the circulating reaction zone 2 through the water inlet pipe 16, the mixed liquid return pipe 37 at the top of the membrane reaction zone 2, and the sludge return pipe 50 at the bottom of the membrane reaction zone 2, where it is fully mixed and reacted.

[0078] Membrane reaction zone 4 is the main area of ​​the MABR reactor for autotrophic denitrification. A perforated water distribution plate 3 (13) divides the membrane reaction zone 4 into upper and lower sections. The lower section of the perforated water distribution plate 13 is the sludge zone 12, and the upper section houses multiple sets of MABR membrane modules 9, which are placed vertically side-by-side on the perforated water distribution plate 13. The height of the sludge zone 12 is 1 / 5 to 1 / 4 of the effective water depth of the membrane reaction zone. The perforated water distribution plate 13 is made of stainless steel (SS304) and has multiple evenly distributed circular water passage holes with a diameter of 15mm to 25mm. The total area of ​​the holes accounts for 15% to 30% of the top surface area of ​​the perforated water distribution plate 13. The perforated water distribution plate 13 is horizontally arranged and firmly fixed on all four sides to the inner wall of the reaction tank 1 and the support beams 10 on the partition plate 5. Sludge and mixed liquor from the bottom sludge zone 12 can evenly enter the membrane reaction zone 4 through the perforated water distribution plate 13.

[0079] Furthermore, the MABR membrane module 9 has a rectangular frame structure made of stainless steel (SS304). It includes, from the outside to the inside, an outer frame 901, a three-dimensional mesh packing layer 902, an inner frame 903, and curtain-type membrane fiber elements 904. Multiple sets of curtain-type membrane fiber elements 904 are vertically installed within the inner frame 903, serving as an oxygen-permeable component to provide dissolved oxygen for aerobic microorganisms and simultaneously providing a surface for their attachment and growth to form the MABR biofilm. The single-sheet curtain-type membrane element 904 is a flat curtain-shaped structure, with its two sides connected to the air inlet riser 905 and the air outlet riser 907, respectively. The air inlet riser 905 is connected to the aeration pipe of the air supply system, and the air outlet riser 907 is connected to the exhaust pipe of the air supply system. Both the air inlet and exhaust risers are made of ABS material with a nominal diameter of 25mm to 50mm. Between the two risers are multiple horizontally distributed filamentous silica membranes with an inner diameter of 0.5mm to 1.2mm and a wall thickness of 0.25mm to 0.5mm. The filamentous silica membranes are arranged horizontally, offset from or even perpendicular to the influent flow direction, forming a cross-flow pattern. This helps to improve the mass transfer rate of the substrate and metabolites in the biofilm on the membrane surface, resulting in a high oxygen transfer rate. The membranes are stable, have a wide pressure tolerance range, and can provide good oxygen supply to the reactor, thereby improving treatment efficiency. The three-dimensional mesh filler layer 902 formed between the outer frame 901 and the inner frame 903 of the membrane module is filled with a three-dimensional mesh filler for attaching autotrophic denitrifying bacteria such as anaerobic ammonia oxidizing bacteria. The spacing between the two frames is usually 150mm to 250mm. The three-dimensional mesh filler is made of modified polypropylene (PP) with a porosity of 97% to 98% and a specific surface area of ​​120 to 140 m2 / m3.

[0080] The air supply system is used to aerate each of the MABR membrane modules 9, and includes an air supply fan 21, an air supply main pipe 24, air supply branch pipes 28, and supporting valves, flow meters, and pressure sensors. The air supply main pipe 24 is connected to the air outlet of the air supply fan 21, and an air supply main pipe valve 22 and an air supply main pipe flow meter 23 are installed on it in sequence. Each membrane module 9 is provided with an independent air supply branch pipe 28, one end of which is connected to the air supply main pipe 24, and the other end is connected to the membrane fiber element inlet pipe 906. Specifically, the air inlet vertical pipe 905 of each curtain-type membrane fiber element 904 is connected to the membrane fiber element inlet pipe 906, and each membrane fiber element inlet pipe 906 is connected to the air supply branch pipe 28. An air supply branch pipe valve 25, an air supply branch pipe flow meter 26, and an air supply branch pipe pressure sensor 27 are installed on the air supply branch pipe 28 in sequence. The gas supply branch valve 25 is an electrically adjustable ball valve used to regulate the gas supply to the membrane module 9; the gas supply branch air flow meter 26 is a vortex gas flow meter, and the gas supply branch pressure sensor 27 is an online pressure sensor, which measure the flow rate and pressure of the gas entering the MABR membrane module 9, respectively. Each membrane module 9 of the MABR reactor is equipped with an exhaust branch pipe 29, which is connected to the membrane fiber element exhaust pipe 908. An exhaust branch pipe valve 30 is installed on it. The exhaust branch pipes 29 of each membrane module are connected to the exhaust main pipe 31 for final venting. Specifically, the exhaust vertical pipe 907 of each curtain-type membrane fiber element 904 is connected to the membrane fiber element exhaust pipe 908, and the exhaust pipes 908 of each membrane fiber element are connected to the exhaust branch pipes 29 of the membrane module.

[0081] The reagent dosing system is used to add sodium nitrite solution to the membrane reaction zone 4 as needed. It includes multiple sets of membrane dosing assemblies 65 between the MABR membrane module 9 and the perforated water distribution plate 13, corresponding to each MABR membrane module 9. The membrane dosing assemblies 65 are arranged horizontally, installed below the outer frame 901 of the membrane module and above the perforated water distribution plate 13. The bottom of the outer frame 901 has legs of a certain height to accommodate the membrane dosing assemblies 65, typically 150mm~200mm high. The membrane dosing assemblies 65 are made of chemical-grade UPVC material. The membrane dosing assemblies 65 are used for adding sodium nitrite solution for regulation during the operation or start-up of the MABR autotrophic denitrification reactor. The membrane dosing assemblies 65 ensure that the added reagent is evenly distributed at the bottom of the membrane module 9 to guarantee a uniform and effective reaction.

[0082] The membrane dosing assembly 65 includes a dosing trunk 6503, which extends upward to the western side of the corresponding MABR membrane assembly 9. The dosing trunk 6503 is provided with multiple parallel dosing perforated tubes 6504. The dosing perforated tubes 6504 have evenly spaced holes on both sides with a diameter of 4-5 mm and a spacing of 100-150 mm. Multiple dosing mains 6503 extend to the outside of the reaction tank 1. Each dosing main 6503 is equipped with a dosing main valve 6502 and is connected to the same dosing distribution pipe 6501. The dosing distribution pipe 6501 is connected to a dosing pipe. The dosing pipe is connected to the nitrite storage tank 64. A nitrite dosing metering pump 62 is provided on the dosing pipe. Valves are provided on the nitrite dosing pump inlet pipe 63 and the nitrite dosing pump outlet pipe 60 of the nitrite dosing pump 62. A nitrite dosing flow meter 61 is located between the nitrite dosing pump outlet pipe 60 and the nitrite dosing metering pump 62.

[0083] The mixed liquor recirculation system is used to recirculate the mixed liquor from membrane reaction zone 4 to circulating reaction zone 2; the sludge recirculation system is used to recirculate the sludge from sludge zone 12 to circulating reaction zone 2, maintaining sufficient nitrifying bacteria and other denitrifying bacteria in circulating reaction zone 2. At this time, the mixed liquor contains nitrate nitrogen produced by anaerobic ammonia oxidation and a small amount of nitrate nitrogen produced by nitrite oxidizing bacteria (NOB). When recirculated to circulating reaction zone 2, under the action of heterotrophic denitrifying bacteria, a heterotrophic denitrification reaction occurs using some of the organic matter in the influent, reducing nitrate nitrogen to nitrogen gas, thus achieving the purpose of denitrification.

[0084] Specifically, the mixed liquor reflux system includes a mixed liquor reflux pipe 37 connected to the upper part of the membrane reaction zone 4, and the sludge reflux system includes a sludge reflux pipe 50 connected to the sludge zone 12. The sludge reflux pipe 50 is provided with a sludge discharge pipe 46. The mixed liquor reflux pipe 37 and the sludge reflux pipe 50 are connected to the circulating reaction zone 2 through a reflux trunk pipe 38. The reflux trunk pipe 38 is provided with a heat exchange system.

[0085] Furthermore, the mixed liquor in the upper part of the membrane reaction zone 4 is discharged from the tank through the mixed liquor discharge pipe 32, and then transported by the mixed liquor return pump 33 through the mixed liquor return pipe 37 to the return main pipe 38, and finally returned to the circulating reaction zone 2 of the reactor 1. The mixed liquor return pipe valve 34, the mixed liquor return pipe check valve 35, and the mixed liquor return flow meter 36 are installed sequentially on the mixed liquor return pipe 37.

[0086] The sludge in the sludge zone 12 at the bottom of the membrane reaction zone 4 is connected to the return main pipe 38 via the sludge return pump 44 and the sludge return pipe 50, and is returned to the circulation reaction zone 2 together with the mixed liquid. A valve is provided in the sludge return pump inlet pipe 43. On the sludge return pipe 50, starting from the outlet of the sludge return pump 44, a sludge return valve 47, a sludge return pipe check valve 48, and a sludge return flowmeter 49 are sequentially provided.

[0087] Furthermore, the heat exchange system includes a heat exchange barrel 39, a heat exchange coil 40, an electric heating tube 41, an electric heating power supply 42, and an on-line thermometer 74 for the heat exchange barrel. The heat exchange barrel 39 is filled with softened water and replenished regularly. After the electric heating power supply 42 is turned on, the appropriate heating temperature is controlled. The return main pipe 38 is connected to the heat exchange coil 40, and the mixed liquid flows in the heat exchange coil 40 and is indirectly heated to the required water temperature. The mixed liquid after heat exchange flows to the circulation reaction zone 2.

[0088] The air agitation system is used to conduct air scouring on each of the MABR membrane modules 9; the air agitation system includes: an air agitation blower 51, an air agitation main pipe 52, air agitation branch pipes 57, air agitation assemblies 58, and auxiliary valves and flow and pressure detection instruments. Specifically, the air agitation blower 51 is connected to the air agitation main pipe 52, and an air agitation main pipe valve 53 and an air agitation main pipe pressure sensor 54 are provided on the air agitation main pipe 52. A plurality of air agitation branch pipes 57 are branched from the air agitation main pipe 51, and each set of membrane modules 9 corresponds to an air agitation branch pipe 57. An air agitation branch pipe air flowmeter 55 and an air agitation branch pipe valve 56 are provided on the air agitation branch pipe 57, which are a vortex street air flowmeter and an electric regulating ball valve respectively, and are used for the measurement and adjustment of the agitation air volume. Each air agitation branch pipe 57 is correspondingly connected to an air agitation assembly 58, and multiple groups of air agitation assemblies 58 are arranged in the bottom sludge zone 12 of the membrane reaction zone 4. Each group of air agitation assemblies 58 corresponds to a group of MABR membrane modules 9, and is used to disperse the introduced air into small bubbles, and uniformly distribute them at the bottom of the MABR membrane modules 9 through the water distribution perforated plate 13. The small bubbles float upward to conduct air shear and scrubbing on the silica membrane filaments in the MABR membrane modules 9, and maintain the normal renewal of the MABR biofilm. The air agitation assembly 58 is in the shape of "丰" and is horizontally arranged at the bottom of the pool. The center of the air agitation assembly 58 is a gas distribution main pipe, and a plurality of air agitation hole pipes 59 are uniformly vertically distributed thereon. One end of the gas distribution main pipe is closed, and the other end is connected to the air agitation branch pipe 57.

[0089] An online monitoring instrumentation system is used to monitor the water quality indicators and influent water quality indicators in the membrane reaction zone 4 in real time. This system includes a PLC control cabinet 75 connected to the chemical dosing system and the gas supply system. The PLC control cabinet 75 contains a programmable controller and a touch control screen. Specifically, the online monitoring instrumentation system includes an online dissolved oxygen meter 66, an online ORP meter 67, an online ammonia nitrogen meter 68, an online nitrate nitrogen meter 69, an online nitrite nitrogen meter 70, an online pH meter 71, and a thermometer, all located within the membrane reaction zone 4 and connected to the PLC control cabinet 75 via a secondary monitoring instrument 72. This system is used to monitor the water quality indicators in the membrane reaction zone 4 in real time. The online monitoring data is used to determine the autotrophic denitrification rate and stability indicators of the continuously operating reactor. This allows for the addition of sodium nitrite when there is a tendency for instability in the short-range nitrification reaction. Combined with other environmental factors, this inhibits the activity of nitrite-oxidizing bacteria (NOB), thereby addressing the problem of poor operational stability in the MABR autotrophic denitrification reactor.

[0090] The online monitoring instrument system also includes an online pH meter 18 and an online ammonia nitrogen meter 19, both mounted on the inlet pipe 16 and connected to the PLC control cabinet 75 via a secondary inlet monitoring instrument 73. The detection probes of the online pH meter and the online ammonia nitrogen meter 19 are housed in a flow-through detection tank 15. The inlet water 14 of the MABR reactor enters the circulation reaction zone of reactor 1 via the flow-through detection tank 15 and the reactor inlet pipe 16. The flow-through detection tank 15 is a sealed cylindrical container with a top cover, made of transparent acrylic, with a diameter of 200mm~250mm and a height of 300mm~400mm, used to install online monitoring probes for monitoring inlet water quality indicators. The top cover of the flow-through detection tank 15 is connected to the tank via a flange, maintaining a good seal. An exhaust valve 17 is installed on the top cover to remove air from the flow-through detection tank 15. Water 14 enters from the bottom of the self-flowing detection tank 15 and flows out from the top to the reactor inlet pipe 16. Valves are installed on both the inlet and outlet pipes of the self-flowing detection tank 15.

[0091] When the above-mentioned device for improving the autotrophic denitrification performance of a MABR reactor is in normal operation:

[0092] ① The influent to the MABR reactor enters from the top of the circulating reaction zone 2, and the returned mixed liquor and sludge also enter the reactor from the top of the circulating reaction zone 2. The upflow agitator 7 in the circulating guide tube 6 is continuously turned on, so that the mixed liquor in the circulating guide tube 6 is continuously lifted, and then falls outside the circulating guide tube 6, thus circulating inside and outside the circulating guide tube 6 to produce sufficient mixing and reaction.

[0093] Because the inoculated sludge contains a small amount of heterotrophic denitrifying bacteria, some of which attach and grow on the surface of the three-dimensional mesh packing material, while others exist in the suspended sludge of sludge zone 12. Through the sludge return system, the suspended heterotrophic denitrifying bacteria circulate between sludge zone 12 and the circulating reaction zone 2. These bacteria utilize the organic matter in the influent as a carbon source, undergoing denitrification in the circulating reaction zone 2. This converts the nitrate nitrogen generated by the anaerobic ammonia oxidation reaction in the returned mixed liquor into nitrogen gas, further reducing the total nitrogen in the MABR reactor effluent.

[0094] ② The wastewater passing through the circulating reaction zone 2 enters the sludge zone 12 at the bottom of the membrane reaction zone 4 through the water passage 11 at the bottom of the partition wall 5, and then enters the MABR membrane module 9 in the membrane reaction zone 4 evenly through the water distribution perforated plate 13.

[0095] The MABR biofilm grown on the surface of the filamentous silica membrane filaments in MABR membrane module 9 is in a partially short-range nitrification state. Due to guided mass transfer, the MABR biofilm exhibits distinct stratification, consisting of aerobic bacteria and facultative bacteria from the inside out. The inner layer of the biofilm near the surface of the filamentous silica membrane filaments mainly consists of aerobic ammonia oxidizing bacteria (AOB) and a small amount of nitrite oxidizing bacteria (NOB). The outer layer of the biofilm mainly consists of facultative bacteria, containing a small amount of heterotrophic denitrifying bacteria and anaerobic ammonia oxidizing bacteria.

[0096] Ammonia nitrogen in the influent is partially nitrified by the MABR biofilm to form nitrite nitrogen. By adjusting the intermittent aeration ratio, the degree of short-cut nitrification is controlled at 50%~55% to facilitate the efficient anaerobic ammonia oxidation denitrification reaction.

[0097] ③ The anaerobic biofilm attached to and growing in the three-dimensional mesh packing layer 902 of the MABR membrane module 9, and the anaerobic ammonia oxidation sludge particles trapped in the lower pores therein, are rich in anaerobic ammonia oxidizing bacteria and heterotrophic denitrifying bacteria. The anaerobic ammonia oxidizing bacteria use the remaining ammonia nitrogen in the wastewater as an electron donor and the nitrite nitrogen produced by the short-cut nitrification reaction of the MABR biofilm as an electron acceptor to carry out the anaerobic ammonia oxidation reaction, converting both into ammonia nitrogen, thereby completing autotrophic denitrification.

[0098] The biofilm on the surface of the three-dimensional mesh packing layer 902 contains a certain amount of heterotrophic denitrifying bacteria. It can use the small amount of available organic matter remaining in the effluent of the circulating reaction zone as a carbon source to denitrify some of the nitrate nitrogen produced by the anaerobic ammonia oxidation reaction and the excess nitrite nitrogen produced by the short-cut nitrification reaction into nitrogen gas, thereby reducing the nitrate nitrogen and nitrite nitrogen in the effluent of the MABR reactor.

[0099] The remaining nitrate nitrogen and nitrite nitrogen in the final membrane reaction zone 4 are returned to the circulating reaction zone 2 with the mixed solution for denitrification reaction again.

[0100] The parameters for normal operation of autotrophic denitrification in a MABR reactor are as follows:

[0101] The MABR reactor receives continuous feedwater, which is ammonia-containing industrial wastewater or domestic sewage with a low carbon-to-nitrogen ratio (BOD to ammonia nitrogen concentration) of 0.5–2.0. The influent COD is 100–200 mg / L, ammonia nitrogen is 50–120 mg / L, total nitrogen is 50–120 mg / L, and pH is 6.5–7.5.

[0102] Continuous mixed liquor reflux, with a mixed liquor reflux ratio of 200%~400%;

[0103] Maintain intermittent aeration membrane system, adjusting the intermittent aeration ratio to 1.0~2.0, i.e., aerating for 30 minutes and stopping aeration for 30~60 minutes, with an air supply pressure of 5 kPa~30 kPa and an air supply flow rate of 2~4 L / (h·m³). 膜丝 Intermittent air agitation, with air agitation for 15-20 seconds every 15-20 minutes, and an air agitation intensity of 0.3-0.6 m. 3 空气 / m 3 池容 .

[0104] Continuous sludge return is maintained, with a sludge return ratio of 50% to 100%.

[0105] When the inlet water temperature is 20~30℃, the indirect heat exchange system of the return main pipe can be stopped, and the MABR reactor can maintain normal operation. In the low-temperature season, when the inlet water temperature is below 15℃, the indirect heat exchange system of the return main pipe needs to be turned on to ensure that the temperature inside the MABR reactor is 20℃~25℃.

[0106] When the MABR autotrophic denitrification reactor is operating normally, the ammonia nitrogen removal rate is 95%~98%, the total nitrogen removal rate is 85%~95%, and the COD removal rate is 50%~80%.

[0107] In a normally operating MABR autotrophic denitrification reactor, the stability of the short-cut nitrification reaction directly affects the conversion rate of influent ammonia nitrogen to nitrite nitrogen and the fluctuation range of nitrite nitrogen accumulation during the short-cut nitrification process, thus impacting the reactor's autotrophic denitrification stability and total nitrogen removal performance. Therefore, it is necessary to monitor and evaluate the stability of the autotrophic denitrification process in the MABR reactor, identify the main factors affecting autotrophic denitrification stability, and implement timely and accurate control measures. Therefore, this invention also provides a method for improving the autotrophic denitrification performance of a MABR reactor.

[0108] An embodiment of a method for improving the autotrophic denitrification performance of a MABR reactor.

[0109] A method for improving the autotrophic denitrification performance of a MABR reactor, employing the aforementioned apparatus for improving the autotrophic denitrification performance of a MABR reactor, comprises the following steps:

[0110] S001. Inoculate and attach biofilm in the MABR reactor, and ensure that the autotrophic denitrification of the MABR reactor operates normally;

[0111] S002. Establish baseline values ​​for various data during normal operation of the autotrophic denitrification process in the MABR reactor and store them in the PLC controller. These data include: dissolved oxygen, pH, oxidation-reduction potential, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and temperature in the membrane reaction zone 4; and ammonia nitrogen, pH, and temperature in the influent. When the autotrophic denitrification process is successfully established in the MABR reactor and continuous influent operation is started, record the online monitoring data in the membrane reaction zone 4 and simultaneously record the online monitoring instrument data in the flow-through detection tank 15 of the influent. Take the monitoring data for 48 consecutive hours and use the average value of each monitoring data as the baseline value for normal operation of the autotrophic denitrification process in the reactor.

[0112] S003. Establish a database for determining the stability decline of the autotrophic denitrification process in the MABR reactor: Based on the changing trends of water quality indicators in the autotrophic denitrification process of the MABR reactor, list the main causes of instability in the autotrophic denitrification process of the MABR reactor.

[0113] The determination database mainly includes the following:

[0114]

[0115] Note: "↗↗": The concentration increases significantly. For pH, this usually means a fluctuation range of + (0.8~1.2).

[0116] "↗": Concentration increases, which in the context of pH usually refers to a fluctuation range of + (0.5~0.8).

[0117] "↘": Concentration decreases, which in the context of pH usually refers to a fluctuation range of (-0.5 to -0.8).

[0118] "↘↘": The concentration drops significantly, which usually means a fluctuation range of (-0.8 to -1.2) for pH.

[0119] "~ 0": The concentration is very low or close to 0.

[0120] S004. Continuously collect online monitoring data of the autotrophic denitrification process in the MABR reactor, and input the data into the PLC controller through the secondary monitoring instrument 72 in the membrane reaction zone and the secondary monitoring instrument 73 in the feed water. Compare the online monitoring data with the reference values ​​of each data, that is, compare the real-time online data in the membrane reaction zone 4, including dissolved oxygen, pH value, redox potential, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and temperature, with the reference values ​​in step S002. Based on the data trend in the judgment database, determine the cause of the instability of the autotrophic denitrification process in the MABR reactor.

[0121] S005. Based on the reasons for the instability of autotrophic denitrification in the MABR reactor in step S004, make corresponding adjustments.

[0122] In some embodiments, the cause of autotrophic denitrification instability in a MABR reactor is:

[0123] ①The activity of nitrite-oxidizing bacteria in the MABR biofilm increases, showing a tendency towards complete nitrification.

[0124] During long-term operation, the MABR autotrophic denitrification reactor primarily employs intermittent aeration to limit dissolved oxygen concentration and inhibit nitrite-oxidizing bacteria (NOB) activity, thus achieving partial short-cut nitrification. However, due to the anisotropic mass transfer process between dissolved oxygen and the substrate within the MABR biofilm—that is, high dissolved oxygen concentration and low substrate concentration in the part of the MABR biofilm in contact with the outer surface of the membrane fibers, and low dissolved oxygen concentration and high substrate concentration in the part of the MABR biofilm in contact with the mixed liquor—nitrite-oxidizing bacteria (NOB) can easily survive inside the biofilm. Furthermore, since both ammonia-oxidizing and nitrite-oxidizing bacteria attach and grow on the surface of the MABR membrane fibers, sludge age is not directly affected by hydraulic retention time, making it difficult to eliminate nitrite-oxidizing bacteria through differences in microbial kinetics. For these reasons, nitrite-oxidizing bacteria (NOB) cannot be completely eliminated in the MABR autotrophic denitrification reactor and always coexist with ammonia-oxidizing bacteria (AOB). Controlling only low dissolved oxygen or other factors cannot achieve a stable short-cut nitrification process.

[0125] Therefore, when the cause of autotrophic denitrification in a MABR reactor is increased activity of nitrite-oxidizing bacteria and a tendency towards complete nitrification, the pH of the mixed liquor will drop significantly, typically to the range of 6.0-6.5. The control method is to add sodium nitrite solution to membrane reaction zone 4, so that the mixed liquor in the reactor produces a sufficient concentration of free nitrite (FNA) at a lower pH. Combined with the low dissolved oxygen brought about by the intermittent aeration mode, this inhibits nitrite-oxidizing bacteria (NOB) in the MABR biofilm, restores the short-cut nitrification process, and the autotrophic denitrification reaction returns to stability.

[0126] The specific method is as follows:

[0127] (1) Start the reagent dosing system and add sodium nitrite solution into the membrane reaction zone 4. That is, open the valves on the nitrite metering pump 62, the inlet pipe 63 of the nitrite hydrochloric acid metering pump, and the outlet pipe 60 of the nitrite metering pump, and add sodium nitrite solution evenly into the membrane reaction zone 4. The concentration of sodium nitrite solution prepared in the nitrite storage tank is 1000~5000 mg / L. The amount of sodium nitrite added to the membrane reaction zone is 0.05~0.08Q, in kg / d, where Q is the influent flow rate. The dosing rate of the nitrite metering pump is 0.01~0.08 m3 / d. At this time, the concentration of free nitrite (FNA) in the mixed solution can reach 0.096~0.189 mg / L.

[0128] Increase the intermittent aeration ratio of the air supply system and maintain it for a period of time; at this time, the intermittent aeration ratio is 2.0~3.0, that is, aerate for 30 minutes and stop aeration for 60 minutes~90 minutes. Other conditions, such as air supply pressure, air supply volume and air agitation method remain unchanged. At this time, the dissolved oxygen concentration in the mixed solution can be controlled below 0.02 mg / L.

[0129] (2) During this process, the nitrate nitrogen concentration in membrane reaction zone 2 is monitored in real time. When the nitrate nitrogen concentration decreases to the baseline value, the instability control strategy is effective. Then, the amount of sodium nitrite added is reduced to 0.02~0.03Q, where the unit is kg / d and Q is the influent volume, and this is maintained for a period of time.

[0130] (3) When the pH value in membrane reaction zone 2 recovers to above 7.0 and the redox potential recovers to 50~100mV, stop adding sodium nitrite and restore the intermittent aeration ratio to the normal operating value. At the same time, restore other control conditions to the normal operating value of autotrophic denitrification of the MABR reactor.

[0131] In some embodiments, the cause of autotrophic denitrification instability in a MABR reactor is:

[0132] ② When the short-cut nitrification reaction of the MABR biofilm is excessive or insufficient, it can be regulated by intermittent aeration mode and influent nitrogen load.

[0133] a. When the short-range nitrification reaction of the MABR biofilm is excessive:

[0134] Analyze the intermittent aeration ratio and influent nitrogen load before and after the instability of the MABR autotrophic nitrogen removal reactor. If the influent nitrogen load does not change significantly, increase the intermittent aeration ratio to 2.0-3.0 and reduce the aeration rate of the MABR reactor, i.e., aerate for 30 min and stop aeration for 60-90 min. If the influent nitrogen load decreases (including a decrease in influent ammonia nitrogen concentration or a decrease in influent flow rate), restore the influent nitrogen load, including increasing the influent flow rate or restoring the influent ammonia nitrogen concentration. If the influent nitrogen load cannot be restored in the short term, increase the intermittent aeration ratio and reduce the aeration time for regulation, i.e., adjust the intermittent aeration ratio to 2.0-4.0 and reduce the aeration time to 15-20 min.

[0135] b. When the short-range nitrification reaction of the MABR biofilm is insufficient:

[0136] Analyze the intermittent aeration ratio and influent nitrogen load before and after the instability of the MABR autotrophic denitrification reactor. If the influent nitrogen load does not change significantly, reduce the intermittent aeration ratio to 0.5~1.0 and increase the reactor's air supply, i.e., aerate for 30 minutes and stop aeration for 15~30 minutes. If the influent nitrogen load increases (including an increase in influent ammonia nitrogen concentration or an increase in influent flow rate), restore the influent nitrogen load, including reducing the influent flow rate or restoring the influent ammonia nitrogen concentration. If the influent nitrogen load cannot be restored in the short term, reduce the intermittent aeration ratio and increase the aeration time for regulation, i.e., adjust the intermittent aeration ratio to 0.5~1.0 and increase the aeration time to 30~60 minutes.

[0137] In some embodiments, the cause of autotrophic denitrification instability in a MABR reactor is:

[0138] ③ The activity of anaerobic ammonia oxidizing bacteria decreased.

[0139] The main reasons for the decline in the activity of anaerobic ammonia oxidizing bacteria during long-term operation of the MABR autotrophic denitrification reactor include: reduced retention of anaerobic ammonia oxidizing bacteria in the reactor; changes in environmental factors affecting the activity of anaerobic ammonia oxidizing bacteria; and long-term instability of the short-cut nitrification reaction, leading to a decrease in anaerobic ammonia oxidizing activity.

[0140] The present invention provides a regulatory strategy for the decline in the activity of anaerobic ammonia oxidizing bacteria. This strategy involves periodically adding sodium nitrite to stabilize the short-cut nitrification process, while simultaneously increasing the substrate for the anaerobic ammonia oxidation reaction, stimulating the growth of anaerobic ammonia oxidizing bacteria, increasing their attachment and growth in the composite membrane module, and improving their retention.

[0141] In a normally operating MABR autotrophic denitrification reactor, the sodium nitrite dosing system is activated for 3 days every 12 days. The sodium nitrite dosage is 0.02~0.03Q (kg / d), where Q is the reactor influent flow rate. During the sodium nitrite dosing period, the intermittent aeration ratio is increased from 1.0~2.0 during normal operation to 2.0~3.0, while other conditions remain at normal operating values. For each subsequent sodium nitrite dosing cycle, the dosage is increased by 0.03~0.05Q (kg / d), while other conditions remain the same.

[0142] In some embodiments, the cause of autotrophic denitrification instability in a MABR reactor is:

[0143] ④ In cases where the concentration of organic matter in the influent continues to rise or the proportion of degradable organic matter continues to increase.

[0144] When the concentration of organic matter in the influent continues to increase or the proportion of biodegradable organic matter in the influent continues to increase, it is easy for heterotrophic nitrifying bacteria or other heterotrophic bacteria to proliferate excessively, causing the living space of anaerobic ammonia oxidizing bacteria to be squeezed out, thus making the autotrophic denitrification process unstable.

[0145] The control strategy for the above situation is to increase the heterotrophic denitrification ratio in the circulating reaction zone, while reducing the heterotrophic denitrification ratio in the spatial three-dimensional mesh packing zone of the membrane reaction zone, thereby reducing the impact of denitrifying bacteria on anaerobic ammonia oxidizing bacteria.

[0146] First, the operating frequency of the variable frequency motor of the upflow mixer 7 in the circulating reaction zone is increased to increase the speed of the mixer, thereby increasing the circulation speed of the mixed liquor inside and outside the circulating guide tube, and thus increasing the heterotrophic denitrification rate in the circulating reaction zone. Second, the reflux ratio of the mixed liquor in the membrane reaction zone is increased from 200%~400% during normal operation to 400%~600% to reduce the nitrate nitrogen concentration in the membrane reaction zone, thereby reducing the reactivity of heterotrophic denitrifying bacteria in the three-dimensional mesh packing area inside the composite membrane module.

[0147] When the concentration of organic matter in the influent continues to rise and the carbon-to-nitrogen ratio exceeds 3.0, it exceeds the applicable scope of the MABR autotrophic denitrification reactor of this invention. It is necessary to adopt an appropriate pretreatment unit (such as activated sludge aeration tank, aerated biological filter, etc.) to appropriately reduce the concentration of organic matter before it enters the MABR autotrophic denitrification reaction for treatment.

[0148] In some embodiments, a method for establishing an autotrophic denitrification process in a MABR reactor is provided.

[0149] For nitrogen-containing industrial wastewater and domestic sewage with low carbon-to-nitrogen ratios, the process of establishing autotrophic denitrification in a MABR reactor can be carried out in steps, including the following steps: biofilm formation of nitrifying biofilm, establishment of short-cut nitrification process, start-up of anaerobic ammonia oxidation autotrophic denitrification process, and establishment of stable autotrophic denitrification process.

[0150] The method for establishing an autotrophic denitrification process in a MABR reactor includes the following steps: S0011, attachment of the nitrifying biofilm:

[0151] (1) Inoculate aerobic activated sludge into the circulating reaction zone 2. The aerobic activated sludge has nitrification function. Activated sludge from the aerobic or anoxic zone of a wastewater treatment system using BNR (Biological Nutrient Removal) or AAO (Anaerobic / Anoxic / Aerobic) processes can be taken. After settling for 30 minutes, the supernatant is skimmed off. The sludge is then added directly to the tank from the top of the circulating reaction zone 2. The amount of inoculated sludge is (2.0~3.0)×V. 膜反应区 The unit is kg, where V 膜反应区 The effective volume of membrane reaction zone 4 is such that the sludge concentration (MLSS) of the mixed liquor in the MABR reactor after inoculation reaches 2000 mg / L~3000 mg / L.

[0152] Continuously activate the stirring and circulation system, the mixed liquor reflux system, and the air supply system; that is, continuously activate the upflow stirrer 7, the mixed liquor reflux pump 33, the valves on the mixed liquor discharge pipe 32, and the mixed liquor reflux pipe valve 34 in the circulation reaction zone 2; start the air supply fan 21, the air supply main pipe valve 22, the air supply branch pipe valve 25, and the exhaust branch pipe valve 30 to keep the MABR membrane module in a continuous aeration state, with an inlet air pressure of 30~50kPa and an inlet air flow rate of 6~8L / (h·m³). 膜丝 ).

[0153] Intermittent water intake is implemented in a cycle of 1 hour of water intake followed by 3 hours of water intake cessation. The air agitation system is intermittently activated, meaning it operates intermittently for 10-20 seconds every 15 minutes during water intake; and continuously during water intake cessation, with an agitation intensity of 0.6-0.9 m. 3 空气 / m 3 池容 .

[0154] Close the sludge return system and the heat exchange system on the return main pipe 38; close the valves on the sludge return pump 44 and the sludge return pump inlet pipe 43.

[0155] During this stage, the flow direction of the sludge-water mixture in the MABR reactor is "circulating reaction zone 2 — sludge zone 12 — water distribution perforated plate 13 — membrane reaction zone 4 — circulating reaction zone 2". Excess water from the reactor during the influent period is discharged through the outlet pipe 20. The intermittent influent mode and continuous MABR membrane aeration ensure relatively complete degradation of organic matter in the influent within the MABR reactor, which is beneficial for the growth of aerobic nitrifying bacteria within the reactor. Simultaneously, the prolonged operation of the air mixing system keeps the activated sludge in a suspended state within the reactor, ensuring good contact with the MABR membrane fibers. This allows aerobic nitrifying bacteria to rapidly attach and grow on the outer surface of the MABR membrane fibers, forming a MABR biofilm.

[0156] (2) When the pH value in membrane reaction zone 4 drops below 6.5~7.0 and the ammonia nitrogen concentration is 5%~10% higher than the influent ammonia nitrogen concentration, gradually increase the proportion of influent time, and increase the influent time by 1 hour each time;

[0157] (3) When the continuous water inlet mode is achieved, the pH value and ammonia nitrogen concentration of the effluent decrease significantly, and a uniform and dense biofilm is attached to the surface of the MABR membrane filaments, the nitrification biofilm attachment stage of the MABR reactor is completed, and a reaction state of complete nitrification is established in the reactor at this time.

[0158] S0012. Establishment of the short-cut nitrification process:

[0159] (1) The MABR reactor maintains a normal flow rate of continuous influent and continuous effluent, and continuously operates the mixed liquor recirculation system and sludge recirculation system. The mixed liquor recirculation ratio is 100%~200%, and the sludge recirculation ratio is 50%~100%.

[0160] The aeration system was adjusted from continuous aeration to intermittent aeration with an intermittent aeration ratio (the ratio of aeration stop time to aeration time) of 1.0–1.5. Simultaneously, the aeration pressure and flow rate were reduced to lower the dissolved oxygen concentration in the reactor, thereby initially inhibiting the activity of nitrite-oxidizing bacteria (NOB) through the low dissolved oxygen concentration. In this intermittent aeration mode, the aeration time was 30–60 min followed by an aeration stop time of 30–60 min, the aeration pressure was 10–30 kPa, and the aeration flow rate was 4–6 L / (h·m³). 膜丝 ).

[0161] (2) Turn on the reagent dosing system and continuously add sodium nitrite solution to the membrane reaction zone (4). The daily dosage of sodium nitrite is calculated based on the influent flow rate (Q), i.e., 0.03~0.05Q, in kg / d. By adding sodium nitrite solution, the concentration of nitrite nitrogen is increased. At pH=6.0~6.5, sufficient free nitrite is generated to inhibit the concentration of nitrite-oxidizing bacteria, thus achieving the rapid establishment of the short-cut nitrification process.

[0162] (3) Turn on the heat exchange system and control the water temperature in the heat exchange tank 39 to 35~40℃. The returned mixed liquor and sludge can undergo continuous indirect heat exchange in the heat exchange tank, while ensuring that the temperature does not exceed the maximum tolerance temperature of the microorganisms. At this time, the dissolved oxygen concentration in the membrane reaction zone of the MABR reactor can be controlled at 0.1~0.2mg / L, the nitrite nitrogen concentration in the influent is 30~50mg / L, and the temperature of the mixed liquor is 25℃~30℃.

[0163] Under nitrification conditions of pH 6.4–6.8, the concentration of free nitrite (FNA) in the mixed liquor of the membrane reaction zone can reach 0.03–0.15 mg / L, which is within the concentration range where FNA inhibits nitrite-oxidizing bacteria (NOB) without adversely affecting ammonia-oxidizing bacteria (AOB). This achieves a synergistic inhibition of nitrite-oxidizing bacteria (NOB) by low dissolved oxygen (DO) and high free nitrite (FNA), thereby suppressing the activity of nitrite-oxidizing bacteria (NOB) in the MABR biofilm, while continuously promoting the proliferation of ammonia-oxidizing bacteria (AOB). The biofilm on the MABR membrane gradually transforms from a fully nitrifying biofilm to a short-range nitrifying biofilm.

[0164] The reaction conversion status is monitored and characterized by an online detection instrument in membrane reaction zone 4. Typically, the dissolved oxygen (DO) is 0.1~0.2 mg / L, the pH is 6.4~6.8, the oxidation-reduction potential (ORP) is 100~200 mV, and the ammonia nitrogen is 5%~10% of the influent ammonia nitrogen value.

[0165] (4) The nitrate nitrogen value in membrane reaction zone 4 shows a gradual decreasing trend. When it decreases to 40%~50% of the stable nitrate nitrogen value when the nitrification biofilm formation stage is completed, the MABR biofilm has initially established a short-range nitrification state. When the nitrate nitrogen value in membrane reaction zone 4 decreases to 80%~90% of the nitrate nitrogen value when the nitrification biofilm formation stage is completed, it indicates that the MABR reaction membrane has completed the short-range nitrification state conversion process, and the addition of sodium nitrite solution is stopped.

[0166] Maintain the heat exchange system, continuous water intake and aeration, and intermittently operate the air stirring system, then continue to operate. When the ammonia nitrogen removal rate of the effluent from membrane reaction zone 4 reaches 92%~98% and the nitrite nitrogen accumulation rate (the ratio of nitrite nitrogen concentration to the sum of nitrite nitrogen and nitrate nitrogen concentrations) reaches 85%~95%, the short-cut nitrification process is established.

[0167] S0013. Start-up of the anaerobic ammonium oxidation autotrophic denitrification process:

[0168] (1) The short-cut nitrification reaction in the MABR reactor is controlled to a partial short-cut nitrification state, so that 50%~60% of the ammonia nitrogen is oxidized to nitrite nitrogen, while ensuring that the nitrite nitrogen accumulation rate is maintained above 95%.

[0169] (2) Based on the continuous influent operation of the MABR reactor under short-cut nitrification conditions, increase the intermittent aeration ratio of the air supply system to 1.5~3.0, i.e., aerate for 30 min and stop aeration for 45 min~90 min; further reduce the aeration pressure and aeration flow rate, with the air supply pressure controlled at 5 kPa~20 kPa and the air supply flow rate at 3~4 L / (h·m 膜丝 This reduces dissolved oxygen in the membrane reaction zone to 0~0.05 mg / L; the ratio of residual ammonia nitrogen to nitrite nitrogen concentration in the effluent is controlled between 1:1 and 1:1.3, and the aeration interval ratio is adjusted accordingly to maintain the dynamic balance of some short-range nitrification.

[0170] (3) Open the sludge discharge pipe and close the sludge return system, that is, open the sludge discharge valve 45 and close the sludge return valve 47 at the same time to discharge about 50% of the sludge in the sludge zone 12 to the outside of the system.

[0171] (4) Inoculate sludge containing anaerobic ammonia oxidizing bacteria in the circulating reaction zone 2. The sludge is a mixture of flocculent sludge and granular sludge containing anaerobic ammonia oxidizing bacteria, with a volume ratio of 1:1 to 2:1. The abundance of anaerobic ammonia oxidizing bacteria in the mixed sludge is not less than 20%, and the inoculation volume is not less than 10% to 20% of the effective volume of the membrane reaction zone.

[0172] Keep the sludge return system closed and the stirring circulation system off. Continuously turn on the mixed liquor return system, air supply system, and heat exchange system on the return trunk line 38, and intermittently turn on the air stirring system. This ensures that the inoculated sludge is fully mixed with the sludge in the reaction tank and circulates between the circulating reaction zone and the membrane reaction zone.

[0173] Other key operating parameters are: reflux ratio of the mixed liquor 400%~600%; the air agitator operates at a frequency of 20 seconds every 10 minutes, with an air agitation intensity of 0.2~0.3 m. 3 空气 / m 3 池容 .

[0174] During the rapid circulation of the mixed liquor, the flocculent sludge comes into full contact with the composite membrane module 9. Due to the large pores in the curtain-type membrane element 904 region inside the composite membrane module 9 and the high water flow velocity, anaerobic ammonia oxidizing bacteria have difficulty attaching and growing. Conversely, the smaller pores in the spatial three-dimensional mesh packing layer 902 and the slower water flow velocity allow anaerobic ammonia oxidizing bacteria to easily attach and grow on the packing surface, forming an anaerobic biofilm. During air mixing, some low-density anaerobic ammonia oxidizing granular sludge can also be retained by the spatial three-dimensional mesh packing layer, forming an anaerobic ammonia oxidizing reaction zone together with the anaerobic biofilm. At the same time, the aerobic biofilm on the surface of the curtain-type membrane element 904 grows more densely under the shearing action of the water flow, which helps to stabilize the short-cut nitrification process.

[0175] (5) The chemical dosing system is coordinated with the intermittent aeration mode. The nitrite dosing system is turned on intermittently. The chemical dosing system is turned on during the last 20% to 30% of the time after aeration stops. Sodium nitrite solution is added to the membrane reaction zone 2. The dosage is calculated based on the influent flow rate (Q) as 0.02 to 0.04Q, with the unit being kg / d. Nitrite dosing is stopped during other time periods.

[0176] The main reason is the periodic change in the short-cut nitrification reaction state during the intermittent aeration of the MABR reactor. The ammonia nitrogen to nitrite nitrogen ratio changes periodically with the short-cut nitrification reaction state, gradually decreasing during aeration and the initial stage of aeration cessation, and gradually increasing in the later stage of aeration cessation. This periodic change in the reaction state has a certain impact on the anammox reaction, especially during the start-up period. By intermittently adding sodium nitrite, ensuring sufficient nitrite nitrogen in the MABR reactor for the anammox bacteria to use, the ammonia nitrogen to nitrite nitrogen ratio in the MABR reactor can be stabilized and brought close to the theoretical value of 1:1.32 for the anammox reaction. This improves the reactivity of the anammox bacteria, reduces the time of prolonged autotrophic denitrification due to the failure of some short-cut nitrification reactions to reach 50%, and shortens the start-up period of autotrophic denitrification.

[0177] (6) After continuous operation for a period of time, a relatively stable anaerobic biofilm is formed in the spatial three-dimensional mesh packing layer in membrane reactor 9; the operation continues until the pH value of the effluent rises to 7.2~7.7 and the oxidation-reduction potential value drops to 50mV~100mV. At this time, the nitrate nitrogen concentration rises to 10%~15% of the influent ammonia nitrogen concentration, and the total nitrogen removal rate of the effluent reaches 70%~80%, thus completing the start-up of the anaerobic ammonia oxidation autotrophic denitrification process.

[0178] S0014. Establishment of a stable autotrophic denitrification process: After the anaerobic ammonia oxidation autotrophic denitrification process is started up, the MABR reactor can be switched from the start-up stage to the normal operation stage.

[0179] Shut down the chemical dosing system, stop adding sodium nitrite solution, and continuously turn on the sludge return system with a sludge return ratio of 50% to 100%. Continuously turn on the mixed liquor return system and the stirring circulation system, and maintain intermittent aeration of the air supply system.

[0180] After continuous operation for a period of time, the total nitrogen removal rate of the MABR reactor effluent reaches 80-85%, the ammonia nitrogen removal rate exceeds 95%, the pH value is 7.0-8.0, and the oxidation-reduction potential is 50mV-100mV. When the influent temperature is 20-30℃, the indirect heat exchange system of the reflux trunk can be stopped, and the MABR reactor can operate normally. At this point, the autotrophic denitrification process of the MABR reactor is established.

[0181] The beneficial effects of using the present invention are as follows:

[0182] (1) This invention proposes a device to improve the autotrophic denitrification performance of MABR reactors for the efficient autotrophic biological denitrification treatment of medium and low concentration ammonia-containing wastewater or domestic sewage. By setting a double-layer frame in the MABR membrane module and embedding a three-dimensional mesh packing material, the attachment of autotrophic denitrifying bacteria such as anaerobic ammonia oxidizing bacteria is increased. A composite membrane module combining curtain-type filamentous silica membrane and three-dimensional mesh packing material is used to construct a system of coupled symbiosis of MABR short-cut nitrification biofilm, anaerobic ammonia oxidation biofilm, and heterotrophic denitrification biofilm. At the same time, different reaction zones such as circulation reaction zone and MABR reaction zone are set in a single reactor, thereby promoting the synergy and integration of multiple denitrification reactions such as short-cut nitrification and denitrification, anaerobic ammonia oxidation and heterotrophic denitrification in a single-stage reactor, improving the autotrophic denitrification efficiency of the reactor, and solving the shortcomings of existing MABR reactors used for autotrophic denitrification, such as the superposition of the disadvantages of the two processes when the MABR membrane module and the biofilm method are simply arranged in the same reactor, and the complexity of multi-stage MABR reactors in series operation.

[0183] (2) This invention proposes a method for establishing an autotrophic denitrification process in a MABR reactor. For nitrogen-containing industrial wastewater and domestic sewage with low carbon-to-nitrogen ratio, the autotrophic denitrification process in the MABR reactor can be carried out in steps, including the following steps: nitrification biofilm formation, establishment of short-cut nitrification process, start-up of anaerobic ammonia oxidation autotrophic denitrification process, and establishment of stable autotrophic denitrification process. By controlling low dissolved oxygen (DO) in the MABR reactor through intermittent aeration and adding sodium nitrite solution to generate a higher concentration of free nitrite (FNA), a multi-factor synergistic inhibition of nitrite-oxidizing bacteria (NOB) is achieved, accelerating the establishment of the short-cut nitrification process in the MABR reactor. Simultaneously, the addition of sodium nitrite solution and the regulation of intermittent aeration improve the start-up speed of the anaerobic ammonia oxidation autotrophic denitrification process and the establishment speed of the stable autotrophic denitrification process. Furthermore, the addition of sodium nitrite solution and the intermittent aeration mode overcome the shortcomings of single-factor inhibition of nitrite-oxidizing bacteria (NOB) activity with poor persistence. Sodium nitrite is also stable, relatively safe to operate, inexpensive, and readily available, making the control strategy of this invention easier to implement in practice.

[0184] (3) This invention proposes a method for assessing the stability of autotrophic denitrification in a MABR reactor. By establishing a baseline value for the normal operation of the autotrophic denitrification process in the MABR reactor and a database for determining the stability decline of the autotrophic denitrification process, the continuously collected online monitoring data is compared with the baseline value of the reactor. Based on the trend in the database, the main causes of the instability of the autotrophic denitrification reaction are obtained. The method for determining the stability of the autotrophic denitrification reactor used in this invention is based on a large amount of historical operating data. It uses the changing trends of multiple parameters of the autotrophic denitrification reactor to determine the stability of the autotrophic denitrification reactor under complex operating conditions. The comprehensive determination method of the changing trends of multiple parameters can match the operating conditions of the MABE membrane module composed of high-efficiency oxygen transfer silica membrane filaments and spatial three-dimensional mesh packing in the MABR reactor. Among them, ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria, heterotrophic denitrifying bacteria and other organisms coexist and coexist, forming a dynamic and stable autotrophic denitrification stabilizer. The method for determining the instability of the reactor does not use a single value or a fixed value, and can obtain the accurate cause of the reactor's instability.

[0185] (4) This invention proposes a method for improving the stability and performance of autotrophic denitrification in a MABR reactor. Different targeted strategies are adopted to regulate the denitrification reaction for different causes of instability. The key to regulating the instability of the short-cut nitrification process is to add sodium nitrite solution, so that the reactor mixture produces a sufficient concentration of free nitrite (FNA) at a low pH value. Combined with the low dissolved oxygen brought about by the intermittent aeration mode, this inhibits the nitrite-oxidizing bacteria (NOB) in the MABR biofilm, restores the short-cut nitrification process, and makes the autotrophic denitrification reaction stable again. In this invention, sodium nitrite solution is continuously added during the continuous operation of the reactor, controlling the pH value between 6.0 and 6.5. This pH range is within the range of pH decrease achievable during complete nitrification, eliminating the need for artificial acid addition. Controlling the FNA concentration inhibits nitrite-oxidizing bacteria without excessively affecting ammonia-oxidizing bacteria. Furthermore, the online addition method directly influences the state of various microorganisms within the MABR reactor, particularly promptly addressing the excessive proliferation of nitrite-oxidizing bacteria without the lag of lateral inhibition. It also directly regulates suspended flocculent sludge, MABR biofilm growing on the MABR membrane filaments, and anaerobic biofilm attached to the three-dimensional mesh packing, thus promoting stable reactor operation. The key to regulating the decline in anaerobic ammonia-oxidizing bacteria activity is the periodic addition of sodium nitrite to stabilize the short-cut nitrification process. Simultaneously, it increases the substrate for anaerobic ammonia oxidation, stimulating the growth of anaerobic ammonia-oxidizing bacteria, increasing their attachment and growth in the composite membrane module, and improving their retention.

[0186] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0187] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for improving the performance of autotrophic denitrification in a MABR reactor, characterized in that, include: The reaction tank (1) is internally divided into a circulating reaction zone (2) and a membrane reaction zone (4) with the bottom connected. The inlet pipe (16) is connected to the circulating reaction zone (2), and the outlet pipe (20) is connected to the membrane reaction zone (4). The circulating reaction zone (2) is equipped with a stirring circulation system, and the membrane reaction zone (4) is equipped with a water distribution perforated plate (13). Below the water distribution perforated plate (13) is a sludge zone (12), and above it are multiple sets of MABR membrane modules (9). The MABR membrane module (9) includes components from the outside to the inside. The membrane module consists of an outer frame (901), a three-dimensional mesh packing layer (902), an inner frame (903), and multiple sets of curtain-type membrane elements (904), arranged sequentially inside. Each curtain-type membrane element (904) includes multiple horizontally uniformly distributed filamentous silicone membranes and an air inlet vertical pipe (905) and an exhaust vertical pipe (907) located on both sides and connected to the two ends of the filamentous silicone membranes, respectively. The air inlet vertical pipe (905) is connected to the aeration pipe of the air supply system, and the exhaust vertical pipe (907) is connected to the exhaust pipe of the air supply system. The chemical dosing system includes multiple sets of membrane zone dosing assemblies (65) located between the MABR membrane module (9) and the water distribution perforated plate (13) and corresponding to each set of MABR membrane module (9); each membrane zone dosing assembly (65) includes a dosing main pipe (6503), which is provided with multiple parallel dosing perforated pipes (6504). The multiple dosing main pipes (6503) extend to the outside of the reaction tank (1) and are connected to a dosing distribution pipe (6501) through a dosing main pipe valve (6502). The dosing distribution pipe (6501) is connected to the dosing pipe, which is connected to the nitrite storage tank (64). The dosing pipe is provided with a valve, a nitrite dosing flow meter (61), and a nitrite dosing metering pump (62). The air supply system is used to aerate each of the MABR membrane modules (9); The mixed liquor reflux system is used to reflux the mixed liquor in the membrane reaction zone (4) back to the circulating reaction zone (2). The sludge return system is used to return the sludge in the sludge zone (12) to the recycling reaction zone (2). An air agitation system is used to scour each of the MABR membrane modules (9) with airflow; An online monitoring instrument system is used to monitor the water quality indicators and influent water quality indicators in the membrane reaction zone (4) in real time, including a PLC control cabinet (75) connected to the chemical dosing system and the gas supply system.

2. The device for improving the performance of autotrophic denitrification of a MABR reactor according to claim 1, characterized in that, The mixed liquor reflux system includes a mixed liquor reflux pipe (37) connected to the upper part of the membrane reaction zone (4), and the sludge reflux system includes a sludge reflux pipe (50) connected to the sludge zone (12). The sludge reflux pipe (50) is provided with a sludge discharge pipe (46). The mixed liquor reflux pipe (37) and the sludge reflux pipe (50) are connected to the circulating reaction zone (2) through a reflux trunk pipe (38). The reflux trunk pipe (38) is provided with a heat exchange system. The air mixing system includes an air mixing component (58) located in the sludge zone (12) and corresponding to each MABR membrane module (9), and the air mixing component (58) is connected to the corresponding air mixing branch pipe (57). The stirring and circulating system includes a circulating guide tube (6) located in the circulating reaction zone (2), and an upflow stirrer (7) is provided in the circulating guide tube (6).

3. The device for improving the performance of autotrophic denitrification of a MABR reactor according to claim 1, characterized in that, The online monitoring instrument system includes an online dissolved oxygen meter (66), an online ORP meter (67), an online ammonia nitrogen meter (68), an online nitrate nitrogen meter (69), an online nitrite nitrogen meter (70), and an online pH meter (71) located in the membrane reaction zone (4) and connected to the PLC control cabinet (75) via a membrane reaction zone monitoring secondary instrument (72), as well as an online pH meter (18) and an online ammonia nitrogen meter (19) located on the inlet pipe (16) and connected to the PLC control cabinet (75) via an inlet water monitoring secondary instrument (73).

4. A method for improving the autotrophic denitrification performance of a MABR reactor, characterized in that, The apparatus for improving the autotrophic denitrification performance of a MABR reactor according to any one of claims 1-3 comprises the following steps: S001. Inoculate and attach biofilm in the MABR reactor, and ensure that the autotrophic denitrification of the MABR reactor operates normally; S002. Establish the baseline values ​​of each data during normal operation of the autotrophic denitrification process of the MABR reactor and store them in the PLC controller. Each data includes: dissolved oxygen, pH value, redox potential, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and temperature in the membrane reaction zone (4); Including ammonia nitrogen, pH value and temperature in the influent; S003. Establish a database for determining the stability decline of the autotrophic denitrification process in the MABR reactor: Based on the changing trends of water quality indicators in the autotrophic denitrification process of the MABR reactor, list the main causes of instability in the autotrophic denitrification process of the MABR reactor. S004. Continuously collect online monitoring data of the autotrophic denitrification process of the MABR reactor and input them into the PLC controller. Compare each online monitoring data with the baseline value of each data and determine the cause of the instability of the autotrophic denitrification process of the MABR reactor based on the data trend in the judgment database. S005. Based on the reasons for the instability of autotrophic denitrification in the MABR reactor in step S004, make corresponding adjustments.

5. The method of claim 4, wherein the MABR reactor is operated at a temperature of 10- 30°C, a pH of 6-8, and a dissolved oxygen concentration of 0.1-2 mg / L. In step S005, the reason for the autotrophic denitrification instability of the MABR reactor is the increased activity of nitrite-oxidizing bacteria in the MABR biofilm, indicating a tendency towards complete nitrification. (1) Turn on the reagent dosing system and add sodium nitrite solution into the membrane reaction zone (4) to increase the intermittent aeration ratio of the gas supply system and maintain it for a period of time; (2) When the nitrate nitrogen concentration decreases to the baseline value, reduce the amount of sodium nitrite added and maintain it for a period of time; (3) When the pH value in the membrane reaction zone (4) recovers to above 7.0 and the oxidation-reduction potential recovers to 50~100mV, stop adding sodium nitrite and restore the intermittent aeration ratio to the normal operating value.

6. The method of improving the performance of autotrophic denitrification in a MABR reactor according to claim 4, characterized in that: In step S005, the reason for the instability of autotrophic denitrification in the MABR reactor is that the degree of short-cut nitrification of the MABR biofilm is excessive or insufficient. This is regulated by intermittent aeration mode and influent nitrogen load. a. When the short-range nitrification reaction of the MABR biofilm is excessive: Analyze the intermittent aeration ratio and influent nitrogen load before and after the instability of the MABR autotrophic denitrification reactor; if the influent nitrogen load does not change significantly, increase the intermittent aeration ratio to 2.0~3.0; if the influent nitrogen load decreases, restore the influent nitrogen load. If the influent nitrogen load cannot be restored in the short term, increase the intermittent aeration ratio to 2.0~4.0, while reducing the aeration time to 15min~20min. b. When the short-range nitrification reaction of the MABR biofilm is insufficient: Analyze the intermittent aeration ratio and influent nitrogen load before and after the instability of the MABR autotrophic denitrification reactor; if the influent nitrogen load does not change significantly, reduce the intermittent aeration ratio to 0.5~1.0; if the influent nitrogen load increases, restore the influent nitrogen load. If the influent nitrogen load cannot be restored in the short term, reduce the intermittent aeration ratio to 0.5~1.0 and increase the aeration time to 30min~60min.

7. The method for improving the autotrophic denitrification performance of a MABR reactor according to claim 4, characterized in that, In step S001, the method for establishing the autotrophic denitrification process in the MABR reactor is as follows: S0011, Nitrifying biofilm attachment: (1) Inoculate aerobic activated sludge into the circulating reaction zone (2) and continuously turn on the stirring circulation system, mixed liquor return system and air supply system; intermittently add water and intermittently turn on the air stirring system; turn off the sludge return system and heat exchange system; (2) When the pH value in the membrane reaction zone (4) drops below 6.5~7.0 and the ammonia nitrogen concentration is 5%~10% lower than the influent ammonia nitrogen concentration, the proportion of influent time is gradually increased; (3) When the continuous influent mode is achieved and the pH value and ammonia nitrogen concentration of the effluent decrease significantly, the nitrification biofilm formation is completed; S0012. Establishment of the short-cut nitrification process: (1) Continuously turn on the mixed liquor return system and sludge return system, adjust the air supply system to intermittent aeration with an intermittent aeration ratio of 1.0~1.5, and reduce the aeration pressure and aeration flow rate at the same time; (2) Turn on the reagent dosing system and continuously add sodium nitrite solution into the membrane reaction zone (4); (3) Turn on the heat exchange system and control the temperature of the mixture to 25℃~30℃; (4) When the nitrate nitrogen value in the membrane reaction zone (4) drops to 80%~90% of the nitrate nitrogen value when the nitrification biofilm is attached, stop adding sodium nitrite solution, keep the heat exchange system running, continuously feed water and aerate, and intermittently turn on the air stirring system, and then run continuously. When the ammonia nitrogen removal rate of the effluent from the membrane reaction zone (4) is 92%~98% and the nitrite nitrogen accumulation rate reaches 85~95%, the short-cut nitrification process is established. S0013. Start-up of the anaerobic ammonium oxidation autotrophic denitrification process: (1) Adjust the short-cut nitration reaction in the MABR reactor to a partially short-cut nitration state; (2) Increase the intermittent aeration ratio of the air supply system to 1.5~3.0, and further reduce the aeration pressure and aeration flow rate; control the ratio of residual ammonia nitrogen to nitrite nitrogen concentration in the effluent between 1:1 and 1:1.3; (3) Open the sludge discharge pipe and close the sludge return system to discharge 50% of the sludge in the sludge zone (12); (4) Inoculate sludge containing anaerobic ammonia oxidizing bacteria in the circulating reaction zone (2), shut down the stirring circulation system, continuously turn on the mixed liquor reflux system, air supply system and heat exchange system, and intermittently turn on the air stirring system; (5) The dosing system is used in conjunction with the intermittent aeration mode. The dosing system is turned on during the last 20% to 30% of the time after aeration stops, and sodium nitrite solution is added to the membrane reaction zone (4). (6) Continue to run until the pH value of the effluent rises to 7.2~7.7, the oxidation-reduction potential value drops to 50mV~100mV, the nitrate nitrogen concentration rises to 10%~15% of the influent ammonia nitrogen concentration, and the total nitrogen removal rate of the effluent reaches 70%~80%, then the anaerobic ammonia oxidation autotrophic denitrification process is started. S0014. Establishment of a stable autotrophic denitrification process: Close the reagent dosing system, continuously turn on the sludge return system, mixed liquor return system and stirring circulation system, maintain intermittent aeration of the air supply system, and continue to operate until the total nitrogen removal rate of the effluent reaches 80~85%, the ammonia nitrogen removal rate exceeds 95%, the pH value is 7.0~8.0, and the oxidation-reduction potential is 50mV~100mV, thus completing the establishment of the autotrophic denitrification process in the MABR reactor.

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