Method and device for operating a membrane aerated biofilm reactor, and wastewater treatment system

Abstract

The present application relates to sewage treatment technical field, disclose a kind of membrane aeration biological membrane reactor's operating method and operating device, sewage treatment system.The operating method has at least one control cycle during the continuous operation of reactor, the cycle includes: pre-control step, provide negative pressure pulse to membrane assembly inside, the normal compressive stress directed to membrane silk inside is applied to the biological membrane attached to the outer surface of membrane, so that the microstrain of outer layer structure is generated;Fluidized cutting step, add and fluidize circulating cutting microparticles to reactor, and microparticles are rolled cutting to the surface of biological membrane under the driving of fluid.By the cutting action of cutting microparticle and negative pressure pulse, the outer layer of biological membrane is selectively stripped from invalid biomass.The present application realizes the fine control from inside to outside to biological membrane under the condition of not interrupting sewage treatment process, can long-term maintain biological membrane in thin, high-activity ideal mass transfer state, effectively solve the problem that mass transfer efficiency attenuates with operating time.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an operation method and device for a membrane aeration biofilm reactor, and a wastewater treatment system. Background Technology

[0002] Membrane-aerated biofilm reactors (MABRs) have demonstrated great potential in energy conservation and emission reduction in wastewater treatment due to their high oxygen mass transfer efficiency and simultaneous nitrification and denitrification capabilities. However, their long-term stable operation faces a technical bottleneck: during operation, the uncontrollable thickening and structural deterioration of the biofilm leads to a continuous decline in mass transfer efficiency. During long-term operation, the continuous metabolic proliferation of microorganisms causes the biofilm to thicken continuously and secrete extracellular polymeric substances (EPS). When the biofilm thickness exceeds the optimal range, a significant mass transfer resistance gradient forms inside. The outer microorganisms age and become inactive due to nutrient deficiency, and accumulate with excess EPS to form a loose, ineffective biomass layer. This layer does not participate in biochemical reactions but becomes the main barrier to the diffusion of substrates into the internal active microbial community, causing a sharp decline in mass transfer efficiency over time.

[0003] To address this issue, existing technologies primarily employ passive intervention methods. For example, increasing the circulation flow rate to flush the membrane surface enhances hydraulic shear, but this approach has limited effectiveness and can easily detach the entire active biofilm, compromising system stability. Another method is offline chemical cleaning, but this requires interrupting the wastewater treatment process and using acids, alkalis, or oxidants for soaking and cleaning. This is not only costly and complex, but residual chemicals can also be toxic to the functional microbial community, resulting in a long system recovery period. Yet another method is gas backwashing, which uses the instantaneous release of high-pressure gas for impact. However, this method suffers from uneven impact force distribution, is ineffective against dense inner biofilms, consumes high energy, and may damage membrane fibers.

[0004] Existing technologies mainly employ passive and destructive treatment methods, which cannot perform online, gentle, and sustainable fine-tuning of the structure and activity of biofilms during normal system operation. Summary of the Invention

[0005] In view of the above, the present invention provides a method and apparatus for operating a membrane aerated biofilm reactor to solve the problems mentioned in the background art.

[0006] In a first aspect, the present invention provides a method for operating a membrane-aerated biofilm reactor, wherein during continuous operation of the reactor, the method comprises at least one control cycle, the control cycle including:

[0007] Pre-conditioning step: A negative pressure pulse is provided to the inside of the membrane module to apply a normal compressive stress pointing inward to the membrane filaments on the biomembrane attached to the outer surface of the membrane, so that the outer structure of the biomembrane produces micro-strain;

[0008] Fluidized cutting step: Cutting particles are added to and fluidized in the reactor, and the cutting particles roll and cut the surface of the biofilm under fluid drive;

[0009] In this process, the cutting action of the cutting particles and the negative pressure pulse are coordinated in time to selectively peel off the outer layer of ineffective biomass of the biofilm while retaining the inner active biofilm.

[0010] Beneficial effects: This application provides a negative pressure pulse to the inside of the membrane module through a pre-regulation step, applying normal compressive stress to the biofilm directed towards the inside of the membrane fibers. This differs from the external-to-inward flushing or impact method in the prior art. It can gently compress the EPS of the biofilm, discharge stagnant water in the pores, and cause micro-strain in the outer aging structure to form a pre-loose state. At the same time, it can shorten the diffusion path of oxygen from the inside of the membrane to the inside of the biofilm, as well as the diffusion path of substrate from the bulk solution to the active bacteria, thereby effectively reducing the overall resistance of anisotropic mass transfer. In the fluidized cutting step, by adding and fluidizing the circulating cutting particles, the negative pressure pulse changes the local flow field, making the cutting particles closer to the membrane surface. During the pre-loosening period of the biofilm in structural response, rolling cutting is performed, thereby accurately and selectively peeling off the pre-loosened outer ineffective biomass layer, while completely preserving the inner highly active functional biofilm. This invention enables precise control of the biofilm from the inside out without interrupting the operation of the MABR, and can maintain the biofilm in an ideal mass transfer state of thinness, density and high activity for a long time, so as to effectively solve the problem of mass transfer efficiency decaying with operating time.

[0011] In some embodiments, the negative pressure intensity of the negative pressure pulse is -3 kPa to -20 kPa, the duration of a single pulse is 1-10 minutes, and the application interval is 1-12 hours.

[0012] Beneficial effects: Using negative pressure intensity of -3 kPa to -20 kPa to generate effective inward normal compressive stress on the biofilm, causing micro-strain in the outer structure and expelling pore water, without causing the entire biofilm to peel off from the membrane surface or damaging the membrane filament structure due to excessive stress; a single application duration of 1-10 minutes ensures that the negative pressure has a sufficient regulatory effect on the biofilm structure, while avoiding excessive dehydration of the biofilm or damage to microbial activity that may be caused by prolonged negative pressure; an application interval of 1-12 hours can be specifically matched to the growth rate of the biofilm, allowing for timely regulation before the biofilm thickens to the point of affecting mass transfer efficiency, forming a cyclical treatment design of growth, regulation, regeneration, and re-regulation, ensuring long-term stable operation of the system.

[0013] In some embodiments, the cutting particles are inert inorganic particles whose surfaces have been modified with hydrophilicity or charged functional groups, and the average particle size of the cutting particles is 50-300 micrometers, with a density of 1.1-2.0 g / cm³. 3 .

[0014] Beneficial effects: By setting the cutting microparticles as inert inorganic microparticles with surface hydrophilic modification or charged functional group modification, the particle size range is 50-300 micrometers and the particle size is 1.1-2.0 g / cm³. 3 The density range ensures that the cutting particles maintain good fluidization within the reactor, preventing them from being too small to settle and recover, or too large or too dense to deposit at the bottom of the reactor and lose their cutting effect. Hydrophilic modification makes the particle surface easier to roll and slide on the hydrophilic biofilm surface, improving cutting efficiency. Modification with charged functional groups allows the particles to adsorb or repel specific functional bacteria, thus applying additional selective pressure to the biofilm community during cutting. This helps guide highly active functional bacteria such as nitrifying and denitrifying bacteria to accumulate on the membrane surface, thereby improving the system's nitrification rate, denitrification efficiency, and resistance to shock loads. Experiments show that under the dynamic operating conditions of the negative pressure pulse and micro-cutting sequence of this invention, the adsorption capacity of amino-modified zeolite particles for nitrifying bacteria is increased by 25% compared to unmodified particles, and the affinity of sulfonic acid-modified particles for denitrifying bacteria is enhanced by 30%. After 180 days of continuous operation, the system using amino-modified particles showed a 12 percentage point increase in the relative abundance of nitrifying bacteria compared to the unmodified system. This effect does not stem from the static adsorption of the particulate material, but rather from the dynamic coupling of negative pressure pulses altering the local flow field and delayed cutting creating selective pressure in the operating method of this invention: negative pressure brings the particles closer to the membrane surface, and delayed cutting occurs during the pre-loosening phase, allowing the surface functional groups of the particles to interact with the target microbial community at the optimal time, thus achieving a leap from physical cleaning to ecological optimization. The selection of inert inorganic materials ensures that the particles will not undergo chemical reactions to release harmful substances during long-term cyclic use, nor will they be degraded by microorganisms, exhibiting good chemical stability and mechanical durability.

[0015] In some embodiments, the inert inorganic particles are at least one of modified zeolite, diatomaceous earth, micron-sized ceramsite, and activated carbon.

[0016] Beneficial effects: Inert inorganic microparticles are selected and matched according to the treatment scenario; among them, modified zeolite has a porous structure and ion exchange capacity, and can adsorb ammonia nitrogen in water while acting as cutting microparticles, thus helping to increase the diffusion flux of ammonia nitrogen from the outer surface to the inner surface of the MABR biofilm, thereby improving nitrification and denitrification effects; diatomaceous earth is lightweight and has a rough surface, with excellent cutting and suspension properties, making it suitable for high-load wastewater treatment scenarios that require high-intensity cutting; micron-sized ceramic particles have high mechanical strength and good wear resistance, making them suitable for large-scale wastewater treatment projects that require long-term recycling and high recovery frequency; activated carbon has a huge specific surface area and adsorption capacity, and can adsorb organic matter and recalcitrant pollutants in water while cutting, providing a more favorable growth environment for microorganisms; these materials are readily available in industry and relatively inexpensive, making it easy to flexibly select and combine them according to different application scenarios, thus reducing operating costs.

[0017] In some embodiments, the negative pressure pulse is triggered by at least one of the following signals: a preset time program, the membrane module gas supply pressure exceeding a set threshold, or the effluent water quality parameters deviating from a set range.

[0018] Beneficial Effects: The preset time program method is suitable for scenarios with relatively stable water quality and quantity and well-defined biofilm growth patterns. Fixed control cycles can be set based on historical operating data for regular preventative maintenance. In constant flow aeration mode, for triggering the control method when the aeration pressure of the membrane module exceeds a set threshold, the control is triggered when the aeration pressure rises above a set proportion, reflecting the increased mass transfer resistance caused by biofilm thickening. For triggering the control method when effluent water quality parameters deviate from the set range, the control is directly linked to the final treatment effect. For example, when the concentration of ammonia nitrogen or total nitrogen in the effluent shows a continuous upward trend, control is immediately activated to ensure that the system always remains within the safe boundary for compliant discharge. Multiple triggering methods can be used individually or in combination to form multiple safeguards, enabling the system to adapt to complex and changing water quality conditions and forming an adaptive control design scheme based on biofilm status feedback.

[0019] Secondly, the present invention provides an operating device for a membrane aeration biofilm reactor, the operating device comprising a reactor and a membrane module immersed in the reactor, the operating device further comprising:

[0020] A bidirectional gas delivery unit is used to alternately supply positive pressure gas and negative pressure suction to the inside of the membrane fiber of the membrane module; the gas delivery pipeline of the bidirectional gas delivery unit is connected to the gas collection end of the membrane module;

[0021] A cutting particle addition and circulation unit is used to add, mix, and recycle cutting particles into the reactor; the addition port of the cutting particle addition and circulation unit is connected to the reactor;

[0022] The control unit is electrically connected to the bidirectional gas delivery unit and the cutting particle dosing and circulation unit, respectively; wherein, the control unit is configured to: control the bidirectional gas delivery unit 201 to generate periodic negative pressure pulses, and during or after the pulses, delay for 30 seconds to 5 minutes, control the cutting particle dosing and circulation unit to adjust the dosing concentration and / or circulation rate of the cutting particles.

[0023] Beneficial effects: The bidirectional gas delivery unit provides positive pressure gas supply during normal operation and negative pressure suction during the control cycle, thus optimizing the operation of the MABR system; the cutting particle addition and circulation unit realizes automatic addition and circulation recovery of cutting particles, ensuring that the effective concentration of cutting particles is always maintained in the reactor; the recycling design reduces the consumption of particles and operating costs; the control unit is configured to control the bidirectional gas delivery unit to generate periodic negative pressure pulses, and adjust the circulation rate and addition concentration of cutting particles during or after the pulse, realizing the timing coordination of the two steps, and realizing the technical means of internal compression pre-loosening followed by external micro-cutting fine finishing.

[0024] In some embodiments, the bidirectional gas delivery unit includes:

[0025] Positive pressure generating device;

[0026] Negative pressure generating device;

[0027] The switching valve has an inlet connected to the positive pressure generating device and the negative pressure generating device, respectively, and an outlet connected to the gas collection end of the membrane module. The switching valve is used to selectively open either the positive pressure gas path or the negative pressure gas path under the control of the control unit.

[0028] Beneficial effects: The independent positive and negative pressure generating devices can be configured separately for both gas supply and suction conditions, thus accommodating both functions and providing timely response; the switching valve, under the control of the control unit, selectively connects either the positive or negative pressure gas path, enabling reliable and rapid switching between the two working modes and ensuring precise execution of the control cycle.

[0029] In some embodiments, the cutting particle dosing and circulation unit includes:

[0030] Particle storage tank, used to store cutting particles;

[0031] A dosing pump, the inlet of which is connected to the particulate storage tank, and the outlet of which is connected to the reactor;

[0032] The solid-liquid separation module and the reflux pump are provided. The inlet side of the solid-liquid separation module is connected to the mixed liquid circulation outlet side of the reactor. The inlet end of the reflux pump is connected to the solid outlet end of the solid-liquid separation module. The outlet end of the reflux pump is connected to the particulate storage tank.

[0033] Beneficial effects: The particulate storage tank is used to store cutting particles, and its volume can be designed appropriately according to the system scale and operational requirements to ensure a long replenishment cycle; the dosing pump enables precise quantitative dosing of cutting particles, accurately controlling the dosing rate and concentration according to the instructions of the control unit to adapt to the control requirements under different operating conditions; the solid-liquid separation module is set on the effluent path of the reactor, which can efficiently intercept and separate the cutting particles lost with the effluent; the reflux pump forces the separated concentrated particles back to the reactor, forming a complete circulation loop; through this closed-loop circulation design, the cutting particles are repeatedly used within the system, and a small amount of particles are replenished periodically according to the loss situation, reducing the operating cost of materials.

[0034] In some embodiments, the control unit is also electrically connected to:

[0035] A pressure sensor for monitoring gas pressure inside the membrane, the pressure sensor being disposed at the gas collection end of the membrane module; and / or;

[0036] A water quality analyzer is used to monitor the quality of the effluent, and the water quality analyzer is installed at the outlet of the reactor.

[0037] Beneficial effects: The pressure sensor, located at the gas collection end of the membrane module, can monitor changes in the gas supply pressure in real time, accurately determining the degree of increase in mass transfer resistance caused by biofilm thickening, thus providing reliable data support for the gas supply pressure feedback triggering mode. The water quality analyzer, located at the reactor outlet, specifically monitors water quality parameters such as ammonia nitrogen, total nitrogen, and COD in real time. When water quality shows a continuous deterioration trend, the control unit promptly initiates the regulation cycle or adjusts the regulation intensity to ensure stable effluent compliance.

[0038] Thirdly, the present invention provides a wastewater treatment system, including the aforementioned operating device.

[0039] Beneficial effects: The integrated operating device in the wastewater treatment system, in addition to traditional wastewater treatment functions, enables online, in-situ, and continuous regulation of MABR biofilm and its activity; it improves the long-term operational stability of the system and avoids the periodic performance decline caused by biofilm thickening in traditional MABR systems. Furthermore, because the mass transfer resistance remains consistently low, it helps reduce the gas supply pressure under the same treatment load, thereby reducing gas supply energy consumption and achieving energy conservation and emission reduction; compared to traditional solutions, it effectively reduces operating costs and the need for manual intervention. Attached Figure Description

[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the operation of the membrane aeration biofilm reactor according to an embodiment of the present invention;

[0042] Figure 2 This is a comparison chart of the changes in ammonia nitrogen concentration in the effluent of the present invention and the traditional MABR process over operating time;

[0043] Figure 3 This is a comparison chart of the gas supply pressure of the membrane module of the present invention and the traditional MABR process as a function of operating time.

[0044] Figure 4 This is a comparison chart of the relative abundance of functional bacterial communities before and after regulation according to the present invention.

[0045] Explanation of reference numerals in the attached figures:

[0046] 101. Reactor; 102. Membrane module; 103. Biofilm; 201. Two-way gas delivery unit; 202. Control unit. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The following is combined with Figures 1 to 4 The following describes embodiments of the present invention.

[0049] According to an embodiment of the present invention, in a first aspect, a method for operating a membrane-aerated biofilm reactor is provided. During continuous operation of the reactor, the method has one or more control cycles. These control cycles mainly include a pre-control step and a fluidization cutting step, through which a beneficial selective pressure is applied to the outer layer of biomass of the ecosystem on the biofilm 103. Specifically, during the conventional bubble-free aeration operation of the reactor 101, this control cycle is periodically executed and cyclical.

[0050] In a specific embodiment, for the pre-regulation step, a negative pressure pulse is provided to the interior of the membrane module 102 to apply a normal compressive stress pointing inwards to the biomembrane 103 attached to the outer surface of the membrane, causing micro-strain in the outer structure of the biomembrane 103. It should be noted that providing a negative pressure pulse to the interior of the membrane module 102 refers to applying negative pressure suction to the inner cavity of the hollow fiber membrane filaments constituting the membrane module 102, causing the negative pressure to act on the inner wall of the membrane filaments, thereby generating a normal compressive stress pointing inwards to the biomembrane 103 attached to the outer surface of the membrane filaments. The negative pressure pulse enters through the gas collection end of the membrane module 102 and is transmitted to the entire biomembrane attachment area via the inner cavity of the membrane filaments.

[0051] For the fluidized cutting step, cutting particles are added to and fluidized into reactor 101. Driven by fluid, these particles perform rolling cuts on the surface of biofilm 103. The cutting action of the particles, coordinated with negative pressure pulses in a sequential manner, strips away the outer layer of ineffective biomass from biofilm 103. The intensity of the negative pressure pulses is configured to keep the inner active biofilm attached to the membrane surface. The negative pressure pulses not only act directly on biofilm 103 but also alter the local flow field near the inner membrane filaments, bringing the cutting particles closer to the biofilm surface. After the negative pressure pulses induce micro-strain in the outer structure of biofilm 103, the cutting particles further perform rolling cuts on the micro-strained biofilm surface to strip away the outer layer of biomass.

[0052] In a specific embodiment, during the pre-regulation step, the negative pressure intensity of the negative pressure pulse is -3 kPa to -20 kPa, the duration of a single pulse is 1-10 minutes, and the application interval is 1-12 hours. This scheme adopts a negative pressure intensity of -3 kPa to -20 kPa to generate effective inward normal compressive stress on the biofilm 103, causing micro-strain in the outer structure and expelling pore water, without causing the biofilm 103 to peel off from the membrane surface or damage the membrane filament structure due to excessive stress; the single pulse duration of 1-10 minutes ensures that the negative pressure has a sufficient regulatory effect on the biofilm structure, while avoiding excessive dehydration of the biofilm 103 or damage to microbial activity that may be caused by prolonged negative pressure; the application interval of 1-12 hours can be specifically matched to the growth rate of the biofilm 103, and timely regulation can be performed before the biofilm 103 thickens to the point of affecting mass transfer efficiency, forming a cyclical treatment design of growth, regulation, regeneration, and re-regulation to ensure long-term stable operation of the system.

[0053] In the specific implementation process, the selection of negative pressure intensity, duration, and interval time is based on the viscoelastic mechanical model of the biomembrane and experimental screening:

[0054] (1) Negative pressure intensity (-3 kPa to -20 kPa): Below -3 kPa, the inward compressive stress is insufficient to generate effective micro-strain in the outer EPS network, resulting in inadequate pore water drainage; above -20 kPa, it may cause the entire biofilm to peel off from the membrane surface or damage the membrane filament structure, and inhibit microbial activity. Through biofilm creep experiments, it was found that the adhesion of the outer layer can be reduced by 30-40% in the range of -8 kPa to -12 kPa, while retaining the activity of the inner layer.

[0055] (2) Duration of a single run (1-10 minutes): According to Fick's second law simulation, about 80% of the pore water can be discharged in 1-2 minutes, and equilibrium is reached in 3-5 minutes; if it exceeds 10 minutes, the activity of microorganisms may decrease due to dehydration. Experiments show that 4 minutes is the optimal value for urban sewage, and high-load wastewater needs to be shortened to 3 minutes to avoid excessive compression.

[0056] (3) Application interval (1-12 hours): Matched to the biofilm growth rate. The biofilm doubling time for urban sewage is about 6-8 hours, so a 6-hour cycle is set; the doubling time for high ammonia nitrogen wastewater is shortened to 3-4 hours, and the cycle is shortened accordingly. If the interval is too long, the biofilm will be too thick, and the control effect will decrease; if it is too short, it will increase energy consumption and may interfere with the normal metabolism of microorganisms.

[0057] In specific embodiments, the negative pressure pulse is triggered by at least one of the following signals: a preset time program, the air supply pressure of the membrane module 102 exceeding a set threshold, or the effluent water quality parameters deviating from a set range. The preset time program triggering method is suitable for scenarios where water quality and quantity are relatively stable and the growth pattern of the biofilm 103 is well-defined. A fixed control cycle can be set based on historical operating data for regular preventative maintenance. In constant flow air supply mode, the triggering method for the air supply pressure of the membrane module 102 exceeding a set threshold reflects the increased mass transfer resistance caused by the thickening of the biofilm 103. Control is triggered when the air supply pressure rises above a set proportion. The triggering method for effluent water quality parameters deviating from a set range directly links the control to the final treatment effect. For example, when the concentration of ammonia nitrogen or total nitrogen in the effluent shows a continuous upward trend, control is immediately initiated to ensure that the system always remains within the safe range for compliant discharge. Multiple triggering methods can be used individually or in combination to form multiple safeguards, enabling the system to adapt to complex and changing water quality conditions and forming an adaptive control design scheme based on biofilm status feedback.

[0058] The pre-regulation step in this invention aims to function through the following means: First, by using negative pressure pulses to induce micro-strain inside the biofilm 103, microorganisms are triggered to adjust the amount and composition of their EPS secretion, such as reducing the secretion of gel-like polysaccharides and increasing more structural protein components, thereby forming a biofilm matrix that is more conducive to mass transfer; Second, mechanical stress serves as an environmental stimulus signal to activate the stress response of microorganisms and enhance their metabolic activity.

[0059] In a specific embodiment, the cutting particles are inert inorganic particles with surface hydrophilic modification or charged functional group modification, and the average particle size of the cutting particles is 50-300 micrometers, with a density of 1.1-2.0 g / cm³. 3 By setting the cutting microparticles as inert inorganic microparticles with surface hydrophilic modification or charged functional group modification, the particle size range is 50-300 micrometers and the particle size is 1.1-2.0 g / cm³. 3 The density range ensures that the cutting particles can maintain a good fluidization state within the reactor 101, preventing them from being difficult to settle and recover due to excessively small particle size, or from depositing at the bottom of the reactor 101 and losing their cutting effect due to excessively large particle size or high density. The hydrophilic modification makes the particle surface easier to roll and slide on the hydrophilic biofilm 103 surface, improving cutting efficiency. The modification of charged functional groups can enable the particles to adsorb or repel specific functional bacterial groups, thereby applying additional selective pressure to the biofilm community during the cutting process. This helps to guide highly active functional bacterial groups such as nitrifying bacteria and denitrifying bacteria to accumulate on the membrane surface, thereby improving the system's nitrification rate, denitrification efficiency, and resistance to shock loads. Experiments show that under the dynamic operating conditions of the present invention, which combines negative pressure pulses with micro-cutting of microparticles, the adsorption capacity of amino-modified zeolite microparticles for nitrifying bacteria is increased by 25% compared to unmodified microparticles, and the affinity of sulfonic acid-modified microparticles for denitrifying bacteria is enhanced by 30%. After 180 days of continuous operation, the system using amino-modified microparticles showed a 12 percentage point increase in the relative abundance of nitrifying bacteria compared to the unmodified system. This effect is not due to the static adsorption of the microparticles, but rather to the dynamic coupling of the negative pressure pulses altering the local flow field and the delayed cutting creating selective pressure in the operating method of the present invention. The negative pressure brings the microparticles closer to the membrane surface, and the delayed cutting occurs during the pre-loosening period, allowing the surface functional groups of the microparticles to interact with the target bacterial community at the optimal time, thus achieving a leap from physical cleaning to ecological optimization. The selection of inert inorganic materials ensures that the microparticles will not undergo chemical reactions to release harmful substances during long-term cyclic use, nor will they be degraded by microorganisms, exhibiting good chemical stability and mechanical durability.

[0060] In specific embodiments, the inert inorganic particles are at least one of modified zeolite, diatomaceous earth, micron-sized ceramsite, and activated carbon. The selection of inert inorganic particles is based on the treatment scenario. Modified zeolite, with its porous structure and ion exchange capacity, can adsorb ammonia nitrogen in the water while acting as cutting particles, thus enhancing denitrification. Diatomaceous earth, with its light weight and rough surface, possesses excellent cutting and suspension properties, making it suitable for high-load wastewater treatment scenarios requiring high-intensity cutting. Micron-sized ceramsite exhibits high mechanical strength and wear resistance, making it suitable for large-scale wastewater treatment projects requiring long-term recycling and high recovery frequencies. Activated carbon has a large specific surface area and adsorption capacity, adsorbing organic matter and recalcitrant pollutants in the water while cutting, providing a more favorable growth environment for microorganisms. These materials are readily available in industry and relatively inexpensive, facilitating flexible selection and combination according to different application scenarios, thereby reducing operating costs.

[0061] In this invention, the fluidized cutting step has a selective effect. Specifically, the continuous and gentle micro-cutting of particles creates a dynamic physical disturbance environment on the membrane surface. This disturbance can form a strong selective pressure, preferentially removing poorly attached and metabolically inactive microbial cells and excessive, loosely structured EPS. Meanwhile, functional bacteria with strong adhesion, vigorous metabolism, and the ability to secrete appropriate amounts of high-quality EPS can survive stably in this disturbance and occupy a dominant ecological niche. This process can guide the biofilm community to naturally eliminate the outer biomass and directionally enrich highly active functional bacteria, thereby forming an ideal biofilm community that is resistant to disturbance and highly active.

[0062] Traditional biofilms are excessively thick and loosely structured, with a large amount of aged EPS and dead cells accumulating on the outer layer, forming a high mass transfer resistance zone with a steep substrate concentration gradient, making it difficult for the substrate to penetrate to the inner active zone. In contrast, an ideal biofilm has a thin and dense structure, with the ineffective outer layer removed, highly active microorganisms evenly distributed, the mass transfer path shortened, the concentration gradient gentler, and the mass transfer efficiency improved.

[0063] Regarding the explanation of the mechanism of this invention, from the perspective of diffusion kinetics, the mass transfer flux follows Fick's first law:

[0064]

[0065] in,

[0066] J Mass transfer flux, kg / (m³) 2 ·s);

[0067] D : Diffusion coefficient, m 2 / s;

[0068] dC / dxConcentration gradient, (kg / m³) 3 ) / m.

[0069] In MABR biofilms, the diffusion pathways of oxygen from the inside of the membrane to the interior of the biofilm, and the diffusion pathways of substrates from the bulk solution to the active bacterial community, determine the overall treatment efficiency of the system. The total mass transfer resistance is composed of membrane resistance, biofilm resistance, and liquid membrane resistance in series, among which biofilm resistance is the most significant factor affecting change.

[0070] biomembrane mass transfer coefficient k_b Inversely proportional to its thickness L f With matrix tortuosity factor τ ,Right now:

[0071]

[0072] in,

[0073] k_b : Biomembrane mass transfer coefficient, m / s;

[0074] L_f : Effective thickness of biofilm, m;

[0075] Matrix tortuosity factor (dimensionless);

[0076] D_w Free diffusion coefficient in water, m 2 / s.

[0077] During long-term operation, microorganisms continuously proliferate and secrete extracellular polymeric substances (EPS), leading to increased biofilm thickness. L_f The layer continues to grow; simultaneously, the aging microorganisms on the outer layer and the accumulation of excessive EPS form a loosely structured, porous, and ineffective biomass layer, increasing the matrix tortuosity factor. τ Significantly increased. L_f Increase and τ Increased common factors lead to effective diffusion coefficient D_ eff The efficiency drops significantly, mass transfer resistance increases dramatically, resulting in a sharp decline in processing efficiency over time.

[0078] The operating method provided by this invention addresses the aforementioned technical bottleneck in mass transfer through two aspects: negative pressure pulses and cutting particles. Specifically, for the negative pressure pulses, by applying negative pressure to the inside of the membrane module 102, an inward and uniform normal compressive stress is generated on the wet biofilm attached to the outer surface of the membrane. This stress gently compresses the EPS network of the biofilm, squeezing out the pore water and bound water retained in the network, which produces two effects: firstly, it directly shortens the diffusion path of oxygen from the inside of the membrane fibers to the inside of the biofilm, and secondly, it shortens the diffusion path of substrates such as ammonia nitrogen from the bulk solution to the active bacterial community inside the biofilm, i.e., it reduces the effective thickness. L_f Secondly, the compression effect straightens the originally tortuous diffusion channels to a certain extent, thus reducing the matrix tortuosity factor. τ Through this process, the effective diffusion coefficient is increased. D_ eff Recovery and improvement are achieved. For the cutting microparticles, inert microparticles are added and fluidized within reactor 101. Driven by the fluid, the microparticles continuously roll, slide, and micro-cut on the surface of the biofilm 103, selectively stripping away the outer, aged biomass layer with the greatest mass transfer resistance, thereby reducing the effective thickness. L_f This exposes a denser, more porous underlying biofilm layer. This design results in a higher density of active cells per unit volume and a shorter, more direct diffusion path, leading to a higher mass transfer coefficient. k_b This allows for an improvement, thereby maintaining long-term mass transfer efficiency.

[0079] In uncontrolled conventional reactors, biofilm growth naturally leads to unfavorable niche stratification. Inner microorganisms, due to their proximity to oxygen sources on the membrane surface, occupy a dominant niche, while outer microorganisms, suffering from nutrient deprivation, gradually age and become inactive, secreting excessive EPS (excessive nutrient uptake) to cope with the adverse environment. This aged and porous outer layer not only fails to participate in biochemical reactions but also hinders substrate diffusion into the inner layer, exacerbating nutrient stress on the inner microorganisms and creating a vicious cycle.

[0080] The regulation cycle of this invention can simulate the mild erosion process in natural ecosystems, exerting beneficial directional selection pressure on biofilm communities.

[0081] The operation method of the membrane aeration biofilm reactor provided in this embodiment, through a pre-regulation step, provides a negative pressure pulse to the inside of the membrane module 102, applying normal compressive stress pointing inward to the biofilm 103. This differs from the outside-in scouring or impact method in the prior art, and can gently compress the EPS of the biofilm 103, discharge stagnant water in the pores, and cause the outer aging structure to produce micro-strain and form a pre-loose state, while shortening the diffusion path of oxygen and substrate. In the fluidized cutting step, by adding and fluidizing the circulating cutting particles, the negative pressure pulse changes the local flow field, making the cutting particles closer to the membrane surface. During the pre-loosening period when the biofilm 103 is in the structural response loosening action, rolling cutting is performed, thereby accurately and selectively peeling off the pre-loosened outer ineffective biomass layer, while completely preserving the inner highly active functional biofilm. This invention enables fine-tuning of the biofilm 103 from the inside out without interrupting the wastewater treatment process, and can maintain the biofilm 103 in an ideal mass transfer state of thinness, density and high activity for a long time, so as to effectively solve the problem of mass transfer efficiency decaying with operating time.

[0082] According to an embodiment of the present invention, in a second aspect, an operating apparatus for a membrane-aerated biofilm reactor is provided, such as... Figure 1 As shown, the operating device includes a reactor 101 and a membrane module 102 immersed in the reactor 101. The operating device also includes a bidirectional gas delivery unit 201, a cutting particle addition and circulation unit, and a control unit 202. The bidirectional gas delivery unit 201 is used to alternately supply positive pressure gas and negative pressure suction to the membrane module 102. The gas delivery pipeline of the bidirectional gas delivery unit 201 is connected to the gas collection end of the membrane module 102. The cutting particle addition and circulation unit is used to add, mix, and circulate cutting particles into the reactor 101. The addition port of the cutting particle addition and circulation unit is connected to the reactor 101. The control unit 202 is electrically connected to the bidirectional gas delivery unit 201 and the cutting particle addition and circulation unit respectively. The control unit 202 is configured to control the bidirectional gas delivery unit 201 to generate periodic negative pressure pulses, and during or after the pulse, control the cutting particle addition and circulation unit to adjust the circulation rate and / or concentration of the cutting particles.

[0083] For the delay control, this embodiment aims to achieve precise timing coupling between negative pressure pre-tightening and micro-cutting. Specifically, the delay range is set according to the viscoelastic mechanical properties of the biofilm: 30 seconds to 2 minutes after the negative pressure pulse is initiated, the outer EPS network of the biofilm is fully compressed, pore water is basically discharged, and the outer layer adhesion is reduced to a minimum. At this time, initiating or enhancing the addition and circulation of cutting microparticles can maximize cutting efficiency. After the negative pressure pulse ends, the biofilm enters the stress relaxation stage, and its outer layer structure remains in a pre-loose state for about 1-5 minutes. During this period, continuing or moderately enhancing the cutting action can further consolidate the peeling effect. Through this delay control, the two physical processes achieve dynamic coordination of internal compression followed by external cutting.

[0084] In a specific embodiment, the bidirectional gas delivery unit 201 includes a positive pressure generating device, a negative pressure generating device, and a switching valve. The inlet of the switching valve is connected to the positive pressure generating device and the negative pressure generating device, respectively, and the outlet of the switching valve is connected to the gas collection end of the membrane module 102. The switching valve is used to selectively open the positive pressure gas path or the negative pressure gas path under the control of the control unit 202.

[0085] This solution employs independent positive and negative pressure generating devices, which can be configured separately for both gas supply and suction conditions, thus accommodating both functions and providing timely response. Under the control of the control unit 202, the switching valve selectively connects either the positive or negative pressure gas path, enabling reliable and rapid switching between the two operating modes and ensuring precise execution of the control cycle.

[0086] In a specific embodiment, the positive pressure generating device is configured as a blower or an air compressor, and the negative pressure generating device is configured as a vacuum pump or a Venturi negative pressure generator.

[0087] In a specific embodiment, the cutting particle dosing and circulation unit includes a particle storage tank, a dosing pump, a solid-liquid separation module, and a reflux pump. The particle storage tank is used to store cutting particles. The inlet of the dosing pump is connected to the particle storage tank, and the outlet of the dosing pump is connected to the reactor 101. The inlet side of the solid-liquid separation module is connected to the mixed liquid circulation outlet side of the reactor 101. The inlet end of the reflux pump is connected to the solid outlet of the solid-liquid separation module, and the outlet end of the reflux pump is connected to the particle storage tank.

[0088] The particulate storage tank is used to store cutting particles. Its volume can be designed to suit the system scale and operational requirements, ensuring a long replenishment cycle. The dosing pump enables precise quantitative dosing of cutting particles, accurately controlling the dosing rate and concentration according to instructions from the control unit 202, adapting to the control requirements under different operating conditions. The solid-liquid separation module is located on the effluent path of reactor 101, efficiently intercepting and separating the cutting particles lost with the effluent. The reflux pump forces the separated concentrated particles back to reactor 101, forming a complete circulation loop. This closed-loop design allows the cutting particles to be repeatedly utilized within the system, with small amounts of particles replenished periodically based on losses, reducing material operating costs.

[0089] In a specific embodiment, the control unit 202 is also electrically connected to a pressure sensor for monitoring the gas pressure inside the membrane. The pressure sensor is located at the gas collection end of the membrane module 102. By placing the pressure sensor at the gas collection end of the membrane module 102, the gas pressure inside the membrane can be monitored in real time. By calculating the change in the gas supply pressure of the membrane module 102, the degree of increase in mass transfer resistance caused by the thickening of the biomembrane 103 can be accurately determined, thereby providing reliable data support for the gas supply pressure feedback triggering mode.

[0090] In a specific embodiment, the control unit 202 is also electrically connected to a water quality analyzer for monitoring the effluent water quality. The water quality analyzer is located at the outlet of the reactor 101. Specifically, the water quality analyzer monitors effluent water quality parameters such as ammonia nitrogen, total nitrogen, and COD in real time. When the water quality shows a continuous deterioration trend, the control unit 202 promptly initiates the control cycle or adjusts the control intensity to ensure that the effluent consistently meets standards.

[0091] The intelligent feedback control mechanism of this invention realizes a transformation from passive execution to active perception and decision-making. Unlike the open-loop cleaning mode based on a fixed schedule in existing technologies, this invention constructs a perception system to detect the true state of the biofilm using pressure sensors and water quality analyzers. The control unit dynamically decides the start timing of the control cycle, the intensity of negative pressure, and the concentration of abrasive particles based on multi-dimensional signals such as changes in air supply pressure and water quality deterioration trends, forming a closed-loop intelligent control system of monitoring, decision-making, execution, and feedback. This on-demand control strategy based on the real-time state of the biofilm not only avoids unnecessary energy and material consumption, but more importantly, it enables precise intervention as soon as signs of functional decline appear in the biofilm, keeping it consistently near an ideal state of thinness, density, and high activity, thus achieving refined and intelligent management of complex biological systems.

[0092] The operating device provided in this embodiment provides positive pressure gas supply during normal operation and negative pressure suction during the control cycle through the bidirectional gas delivery unit 201, thereby optimizing and transforming the MABR system. The cutting particle addition and circulation unit realizes automatic addition and recycling of cutting particles, ensuring that the effective concentration of cutting particles is always maintained in the reactor 101. The recycling design reduces the consumption of particles and operating costs. The control unit 202 is configured to control the bidirectional gas delivery unit 201 to generate periodic negative pressure pulses, and adjust the circulation rate and addition concentration of cutting particles during or after the pulse, so as to realize the timing coordination of the two steps and realize the technical means of first internal compression and pre-loosening, and then external micro-cutting and fine finishing.

[0093] Example 1: MABR system for upgrading and retrofitting urban wastewater treatment plants

[0094] 1. System upgrade;

[0095] In an existing A 2 In the aerobic tank of the / O process, a MABR membrane module is submerged and installed. The membrane material is an oxygen-permeable membrane with a fiber length of 1.5 m and a packing density of 30%. The operating device provided by this invention is installed simultaneously. Its treatment capacity is 50 m³ / s. 3 / d, the influent is pretreated urban sewage, with the following specific water quality characteristics: COD concentration 180-250 mg / L, ammonia nitrogen concentration 25-35 mg / L, total nitrogen concentration 30-45 mg / L, suspended solids concentration 80-120 mg / L, and water temperature 15-25 ℃.

[0096] 2. Equipment configuration;

[0097] The operating device used in this embodiment specifically includes a reactor 101, a bidirectional gas conveying unit 201, a cutting particle dosing and circulation unit, and a control unit 202. The effective volume of the reactor is 100 m³. 3 The system incorporates the aforementioned MABR membrane module; the bidirectional gas delivery unit 201 includes a positive pressure generator, a negative pressure generator, and a switching valve. The positive pressure generator employs a Roots blower with an air volume of 10 m³ / s. 3 The negative pressure generating device uses a water ring vacuum pump with an ultimate vacuum of -30 kPa. The switching valve is connected to the gas collection end of the membrane module through a gas supply pipeline. The microparticle feeding and circulation unit includes a microparticle storage tank, a feeding pump, a solid-liquid separation module, and a reflux pump. The volume of the microparticle storage tank is 1 m³. 3 The solid-liquid separation module uses a hydrocyclone separator, capable of separating particles with a diameter ≥50μm. The control unit is PLC-based and is specifically connected to a pressure sensor and a water quality analyzer, which monitors ammonia nitrogen concentration, total nitrogen concentration, COD concentration, etc.

[0098] 3. Parameter settings;

[0099] This embodiment employs a control strategy of time-based master control and fine-tuning of gas supply pressure. Specific parameters are as follows:

[0100] Negative pressure pulse: It is activated once every 6 hours of operation, with the negative pressure intensity set to -8 kPa and the duration of each pulse being 4 minutes.

[0101] Cutting microparticles: Amino-modified zeolite microparticles with a particle size of 200 μm and a density of 1.6 g / cm³ were used. 3 The initial dosage concentration is 150 mg / L; a recovery rate of over 99% is achieved through a hydrocyclone separator, requiring only about 5% replenishment per week to compensate for losses.

[0102] Triggering logic: The control is adjusted in a fixed cycle of 6 hours. If the gas supply pressure of the membrane module rises by more than 25% of the initial value before the end of the cycle, the control cycle is triggered in advance.

[0103] Delay setting: About 1 minute after the negative pressure pulse is started, the control unit automatically increases the frequency of the cutting microparticle dosing pump by 20% to enhance the microparticle circulation concentration; after the negative pressure pulse ends, the enhanced state continues for 3 minutes, and then automatically returns to the basic circulation concentration.

[0104] 4. Running effect;

[0105] After the system was modified, it ran continuously for 200 days and achieved the following results:

[0106] The effluent ammonia nitrogen concentration remained stable below 1.0 mg / L, the total nitrogen concentration remained stable below 5.0 mg / L, and the COD concentration remained stable below 30 mg / L, with fluctuations in each indicator not exceeding ±5%.

[0107] Figure 3 Standardized gas supply pressures (with the initial gas supply pressure of each system as 100%) are displayed to facilitate comparison of relative trends. The initial gas supply pressure of the system in this invention is 12.5 kPa, and the initial gas supply pressure of the conventional system is 12.5 kPa (the same as in this invention). Gas supply pressure is a direct indicator of the mass transfer resistance of the MABR system in constant flow gas supply mode: the smaller the pressure rise, the slower the biofilm thickening and the lower the oxygen permeation resistance. Figure 3 This invention demonstrates its effectiveness in controlling the increase in mass transfer resistance. After 200 days of operation, the gas supply pressure of the system with this invention was 13.5 kPa (an increase of 8% to 108% of the initial value); while the gas supply pressure of the conventional MABR system had already risen to 18.1 kPa (an increase of 45% to 145% of the initial value) before the first cleaning (day 30), and although it briefly recovered after cleaning, it subsequently climbed again. Figure 3 Quantitative methods have demonstrated that the present invention's control effect on mass transfer resistance is far superior to that of traditional offline cleaning methods.

[0108] The membrane module's permeability remained above 92% of that of a new membrane, with the gas supply pressure increasing by only 8%, indicating that mass transfer resistance was effectively controlled. Compared to the previous simple MABR mode, which required offline chemical cleaning every 30 days, energy consumption was reduced by 22%, and downtime for chemical cleaning was completely eliminated, significantly reducing operating costs. It should be noted that the excellent performance of only an 8% increase in gas supply pressure during 200 days of long-term operation in this embodiment is fundamentally due to the synergistic effect verified in Experiment Example 1: if only negative pressure or particle control (corresponding to control groups B or C) were used, the gas supply pressure increase during the same period would be expected to reach 25-30%, based on the data from Experiment Example 1. It is precisely because the timing coordination of negative pressure pre-tightening and delayed cutting produced a synergistic effect that the biofilm thickening rate was effectively suppressed, and the mass transfer resistance remained at a low level.

[0109] After 200 days of operation, the biofilm thickness was measured and the microbial community was analyzed. The results showed that the biofilm thickness was maintained in the ideal range of 200-250 μm, and the relative abundance of nitrifying bacteria and denitrifying bacteria was increased by about 30% compared with the traditional model.

[0110] This embodiment demonstrates that the method and apparatus described in this invention can achieve long-term stable operation in urban wastewater treatment scenarios, effectively solving the problem of mass transfer efficiency decline caused by biofilm thickening in traditional MABR systems. The fundamental reason for this excellent long-term performance lies in the unique combination of negative pressure pre-tightening and micro-cutting timing in the method of this invention. The negative pressure pulse creates a pre-loosening action period, and the delayed cutting precisely peels off the ineffective layer during this period. The coupling of the two produces a synergistic effect (verified by the experimental example below), which keeps the biofilm in a thin, dense, and highly active state, thereby avoiding the cumulative increase of mass transfer resistance.

[0111] The above effects are achieved through Figures 2 to 4 It can be presented intuitively:

[0112] Figure 2 The graph shows a comparison of the effluent ammonia nitrogen concentration changes over time between the present invention and the traditional MABR process. It demonstrates that during 200 days of continuous operation, the ammonia nitrogen concentration in the effluent of the present invention remained stable below 1.0 mg / L, with fluctuations not exceeding ±5%, while the traditional process exhibited a sawtooth-like fluctuation characteristic, periodically decreasing to 8-10 mg / L every 30 days, followed by a brief recovery after cleaning. This comparison directly confirms the long-term maintenance capability of the present invention for biofilm mass transfer efficiency. The fundamental reason for the smooth effluent ammonia nitrogen curve in the present invention is that, through the synergistic regulation mechanism verified in Experiment Example 1, the system can continuously and online remove ineffective biomass from the outer layer, avoiding the precipitous drop in mass transfer efficiency caused by the cumulative thickening of the biofilm in the traditional process.

[0113] Figure 3This is a comparison graph showing the change in gas supply pressure of the membrane modules of this invention and the traditional MABR process over operating time. To facilitate comparison of the mass transfer resistance trends of different systems, Figure 3 The standardized gas supply pressure is shown (with the initial gas supply pressure of each system as 100%). In this invention, the gas supply pressure only increased by 8% over 200 days (from 12.5 kPa to 13.5 kPa), indicating that mass transfer resistance was effectively controlled. In contrast, the gas supply pressure in traditional processes periodically climbed to over 145% of the initial value every 30 days. Although it recovered briefly after cleaning, it could not return to the initial level, showing a cumulative deterioration trend. The reason for the gradual increase in the gas supply pressure curve in this invention is that the timing coordination of negative pressure pulses and micro-cutting continuously optimizes the pore structure of the biofilm, maintaining the effective diffusion coefficient at a high level. The accumulation rate of mass transfer resistance is much lower than the natural growth rate of the biofilm, achieving a dynamic balance between growth and regulation.

[0114] Figure 4 The diagram shows a comparison of the relative abundance of functional microbial communities before and after the regulation process of this invention. It illustrates that the relative abundance of nitrifying bacteria and denitrifying bacteria increased from 20.0% and 15.0% before regulation to 26.0% and 19.5% respectively (both increases of 30%), while the abundance of the two types of functional microbial communities decreased to 15.0% and 10.0% respectively after 180 days of operation using the traditional process. This ecological optimization effect is attributed to the dynamic selective pressure of this invention: the time-series synergy of negative pressure pulses and delayed cutting selectively removes poorly attached and metabolically low-quality microbial communities during the pre-loosening phase. Simultaneously, the surface functional groups of the particles interact more effectively with the target microbial communities in the flow field altered by negative pressure, thereby directionally enriching highly active functional microbial communities. This invention achieves a transformation from physical cleaning to ecological optimization by directionally enriching highly active functional microbial communities through continuous and mild physical selective pressure. Optimization of the microbial community structure is a guarantee for the system's resistance to shock loads and long-term stable operation.

[0115] To further clarify the optimal parameter ranges for negative pressure intensity, duration, and interval, multiple control experiments were conducted based on Example 1 to investigate the effects of different parameter combinations on the biomembrane regulation effect. The results are shown in the table below:

[0116] Table 1 Negative pressure strength test (fixed duration 4 minutes, interval 6 hours)

[0117]

[0118] Table 2 Duration Experiment (fixed -8 kPa, 6-hour intervals)

[0119]

[0120] Table 3. Interval time experiment (fixed -8 kPa, lasting 4 minutes)

[0121]

[0122] The above experiments show that the preferred negative pressure intensity is -8 kPa to -12 kPa, the preferred duration is 2-6 minutes, and the preferred interval is 4-8 hours. Within this preferred range, the outer layer peeling rate can be ≥68% while ensuring an inner layer activity retention rate of ≥95%, and the gas supply pressure rise can be controlled within 8%, resulting in the best overall effect.

[0123] Example 2: MABR system for treating high ammonia nitrogen aquaculture wastewater

[0124] 1. System design;

[0125] A wastewater treatment plant of a large-scale pig farm was equipped with the operating device described in this invention, with a treatment capacity of 20m³. 3 / d. In response to the characteristics of high ammonia nitrogen concentration (>200 mg / L) in aquaculture wastewater, which easily induces rapid biofilm growth, the equipment and parameters were specifically designed. The influent water quality characteristics are as follows: COD concentration 800-1500 mg / L, ammonia nitrogen concentration 200-350 mg / L, total nitrogen concentration 250-400 mg / L, suspended solids concentration 300-600 mg / L, carbon-to-nitrogen ratio approximately 3-5:1, and water temperature 20-30℃.

[0126] 2. Parameter settings;

[0127] The control strategy in this embodiment has the following specific parameters:

[0128] Negative pressure pulse: Increase the control frequency to once every 3 hours, increase the negative pressure intensity to -12kPa, and the duration of a single pulse is 3 minutes;

[0129] Cutting microparticles: Rough-surfaced hydrophilic diatomaceous earth microparticles with an average particle size of 80 μm and a density of 1.3 g / cm³ were selected. 3 To enhance cutting ability, the initial dosage concentration was increased to 300 mg / L;

[0130] Control logic: The ammonia nitrogen concentration in the effluent is added as a feedback variable. When the ammonia nitrogen in the effluent shows a continuous upward trend, such as when the value increases by more than 10% in two consecutive tests, the negative pressure pulse frequency is automatically increased by 50% temporarily, for example, once every 2 hours, until the water quality stabilizes and the original frequency is automatically restored.

[0131] Delay setting: For high-load conditions, the delay is shortened to 30 seconds after the negative pressure pulse is started, and the enhanced state is maintained for 5 minutes after the pulse ends, so as to ensure effective control of the rapidly growing biofilm.

[0132] 3. Running effect;

[0133] The system ran continuously for 180 days and achieved the following results:

[0134] Excessive growth of biofilm was effectively controlled, and the biofilm thickness remained stable in the range of 180-220 μm, without any processing failure due to deterioration of mass transfer.

[0135] Under low carbon-to-nitrogen ratio (3-5:1) conditions, by maintaining high biofilm activity, a total nitrogen removal rate of 85-90% was still achieved, with an average effluent ammonia nitrogen concentration of 12.5 mg / L and an average effluent total nitrogen concentration of 35.8 mg / L.

[0136] The ability to withstand shock loads is enhanced. Under ammonia nitrogen shock load (increased from 250 mg / L to 450 mg / L), the effluent ammonia nitrogen level rose to a maximum of 18.5 mg / L and returned to normal levels within 48 hours.

[0137] Average aeration energy consumption: 0.45 kW·h / m 3 It saves approximately 25-40% more energy than conventional high ammonia nitrogen treatment processes;

[0138] No offline chemical cleaning was performed throughout the entire process, and after 180 days of operation, the membrane module's permeability remained at 88% of that of a new membrane.

[0139] This embodiment demonstrates that the operating method and device described in this invention can effectively address the challenge of rapid biofilm growth in high-ammonia nitrogen and high-load aquaculture wastewater treatment scenarios, enhance the system's resistance to shock loads, and maintain efficient denitrification under low carbon-to-nitrogen ratio conditions. This effect is also based on the synergistic mechanism verified by the experimental example: after optimizing the negative pressure intensity and delay parameters for high-load conditions, the timing coordination between negative pressure pre-tightening and microparticle micro-cutting is closer, enabling timely removal of the ineffective layer under conditions of rapid biofilm growth. At the same time, the functional groups on the particle surface continuously apply selective pressure in the dynamic flow field, allowing the system to maintain a highly active biofilm structure under high loads.

[0140] Experiment Example 3: Verification of the Synergistic Effect of Negative Pressure Preload and Particle Cutting

[0141] To verify the synergistic effect of negative pressure pre-tightening and microparticle micro-cutting in this invention, a comparative experiment was conducted. The experiment used MABR membrane modules of the same specifications (membrane area 0.5 m²). 2 The study used a simulated urban wastewater treatment system (ammonia nitrogen 30±2 mg / L, COD 200±10 mg / L). Three parallel samples were set up for each experiment, and samples were taken and measured after 30 days of operation. Results are expressed as mean ± standard deviation. Stripping efficiency was determined by gravimetric method (difference in dry weight of biofilm before and after stripping / initial dry weight), mass transfer coefficient was calculated by oxygen transfer rate method, and energy consumption was recorded in real time using an electrical parameter instrument. Four control groups were set up under the same operating conditions.

[0142] Control group A: No regulation was applied; it operated naturally.

[0143] Control group B: Only negative pressure pulses (-8 kPa, once every 6 hours, lasting 4 minutes) were applied.

[0144] Control group C: Only cutting microparticles (modified zeolite with a particle size of 200 μm and a concentration of 150 mg / L) were added.

[0145] Experimental Group D: Synergistic regulation of the present invention (negative pressure pulse and cutting particles, delayed for 1 minute).

[0146] After 30 days of operation, the changes in the outer layer peeling efficiency and mass transfer coefficient of the biofilm were measured, and the results are shown in the table below:

[0147] Table 4. Changes in the four control groups under the same operating conditions.

[0148]

[0149] Experimental data were analyzed using SPSS 26.0 software via one-way ANOVA, with a p-value < 0.05 considered significant for differences between groups. The results showed that the stripping efficiency of experimental group D (68.2 ± 2.1%) was statistically significantly different from that of control groups B (28.1 ± 1.8%), C (35.3 ± 2.2%), and the theoretical cumulative value (63.4%) (p < 0.01). The mass transfer coefficient retention rate also showed a significant difference (p < 0.05).

[0150] To verify the reliability of the experimental results, three batches of experiments were repeated under the same operating conditions. The results of each batch are shown in the table below:

[0151] Table 5. Repeated experiments under the same operating conditions (3 batches)

[0152]

[0153] The results of the three batches of experiments were highly consistent, with coefficients of variation all less than 3%, demonstrating that the data have good repeatability and reliability.

[0154] The results showed that the stripping efficiency of negative pressure alone or individual particles alone was 28.1% and 35.3%, respectively, while the expected value for simple superposition was 63.4%. The synergistic regulation of this invention actually achieved 68.2%, exceeding the simple superposition value by 5 percentage points. The mass transfer coefficient retention rate was 96%, far higher than the 78% and 81% achieved by individual actions, and the energy consumption reduction was more significant. This fully demonstrates that the synergistic effect produced by the timing coordination of negative pressure pulses and cutting particles cannot be achieved by simple superposition. This synergistic mechanism is the fundamental reason for the long-term stable operation in Examples 1 and 2: the negative pressure pulse creates a pre-loosening period, and the delayed cutting precisely strips the ineffective layer during this period. The coupling of the two keeps the biofilm in a thin, dense, and highly active state, thereby avoiding the cumulative increase in mass transfer resistance.

[0155] In this invention, the timing coordination of negative pressure pulses and micro-cutting of microparticles can produce a synergistic effect, the physical and biological mechanisms of which are as follows:

[0156] (1) Physical level – compression followed by unblocking of pore structure: The negative pressure pulse first applies inward normal compressive stress to the biofilm, causing the pore water in the outer EPS network to be squeezed out, the biofilm volume to shrink, and the pore tortuosity factor τ to decrease; at the same time, the compression effect reduces the adhesion of the outer layer, forming a pre-loosening action period. At this time, micro-cutting of microparticles is performed, and the cutting microparticles can more easily enter the loosened pore channels and peel off the aged biomass. If cutting is performed first and then negative pressure is applied, the cutting resistance is large and the inner layer is easily damaged; if there is no negative pressure pre-tightening, the cutting only acts on the surface. The timing coordination of the present invention makes the compression and cutting complementary in space and relayed in time, realizing the optimal physical process of first compressing to reduce resistance and then cutting to remove the waste.

[0157] (2) Biological Level – Directed Selection of Microbial Communities: The micro-strain generated by the negative pressure pulse can induce microorganisms to adjust EPS secretion (reducing gel-like polysaccharides and increasing structural proteins), making the biofilm matrix more conducive to mass transfer. Delayed cutting is carried out during the pre-loosening action period, preferentially removing aging bacteria with poor adhesion and low metabolism, while having less impact on functional bacteria with strong adhesion and vigorous metabolism (such as nitrifying bacteria). At the same time, the surface functional groups of the cutting particles interact more effectively with the target bacteria in the flow field changed by negative pressure, forming continuous selection pressure. This biological process of induction followed by selection allows the system to complete the directed optimization of the microbial community while physically cleaning.

[0158] This invention achieves a synergistic effect through the sequential coordination of negative pressure pre-tightening and micro-cutting. The negative pressure pulse induces micro-strain in the outer layer of aged biomass, reducing adhesion and creating a unique pre-loosening period for subsequent cutting. Cutting during this period improves peeling efficiency by over 30% compared to direct cutting without pre-tightening. Simultaneously, the disturbance of the flow field by the cutting microparticles further amplifies the compression effect of negative pressure on the biofilm's pore structure, increasing the effective diffusion path shortening by 15-20% compared to the algebraic sum of the effects of either technique alone. This dynamic, mutually reinforcing mechanism cannot be achieved by a single technology or simple combination.

[0159] The above effects are achieved through Figures 2 to 4 It can be presented intuitively: Figure 2 This indicates that the present invention has achieved stable operation for up to 200 days, completely getting rid of the periodic decay problem of traditional processes; Figure 3 This invention demonstrates that its effect on controlling mass transfer resistance is far superior to that of traditional offline cleaning methods. Figure 4 This reveals the targeted enrichment effect of the present invention on functional microbial communities at the microbial level, confirming its transformation from physical cleaning to ecological regulation.

[0160] According to an embodiment of the present invention, a third aspect provides a wastewater treatment system including the above-described operating apparatus.

[0161] The wastewater treatment system provided in this embodiment integrates an operating device, which, in addition to traditional wastewater treatment functions, enables online, in-situ, and continuous regulation of MABR biofilm and its activity. This improves the long-term operational stability of the system and avoids the periodic performance degradation caused by biofilm thickening in traditional MABR systems. Furthermore, because the mass transfer resistance remains consistently low, it helps to reduce the air supply pressure under the same treatment load, thereby reducing aeration energy consumption and achieving energy saving and consumption reduction. Compared to traditional solutions, this effectively reduces operating costs and the need for manual intervention.

[0162] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for operating a membrane aerated biofilm reactor, characterized in that, During the continuous operation of the reactor (101), the operation method has at least one regulation cycle, the regulation cycle comprising: a pre-regulation step: providing a negative pressure pulse to the inside of the membrane module (102) to exert a normal compressive stress directed to the inside of the membrane filament on the biofilm (103) attached to the outer surface of the membrane, so as to produce a micro-strain on the outer structure of the biofilm (103); a fluidized cutting step: adding and fluidizing circulating cutting particles in the reactor (101), the cutting particles rolling and cutting the surface of the biofilm (103) under the driving of fluid; wherein the cutting effect of the cutting particles and the negative pressure pulse are matched in time sequence to selectively strip the outer layer of the biofilm (103) of the ineffective biomass; the negative pressure intensity of the negative pressure pulse is -3 kPa to -20 kPa, the single duration is 1-10 minutes, and the application interval is 1-12 hours; The cutting microparticles are inert inorganic microparticles whose surfaces are modified with hydrophilization or charged functional groups, the average particle diameter of the cutting microparticles is 50 to 300 micrometers, and the density is 1.1 to 2.0 g / cm 3 .

2. The method of operating of claim 1, wherein, the inert inorganic particles are at least one of modified zeolite, diatomite, micron ceramic, and activated carbon.

3. The method of operating of claim 1, wherein, The start of the negative pressure pulse is triggered by at least one of a preset time program, a gas supply pressure of the membrane module (102) exceeding a set threshold, and a water quality parameter deviating from a set range.

4. A membrane aerated biofilm reactor operating device for carrying out the operating method according to any one of claims 1 to 3, said operating device being provided with a reactor (101) and a membrane module (102) immersed in said reactor (101), characterized in that, The operation device further comprises: a bidirectional gas delivery unit (201) for alternately providing positive pressure gas supply and negative pressure suction to the inside of the membrane module (102); the gas delivery pipeline of the bidirectional gas delivery unit (201) is connected with the gas collection end of the membrane module (102), a cutting particle adding and circulating unit for adding, mixing and recycling the cutting particles in the reactor (101); the adding port of the cutting particle adding and circulating unit is communicated with the reactor (101); a control unit (202) electrically connected with the bidirectional gas delivery unit (201) and the cutting particle adding and circulating unit, respectively; wherein the control unit (202) is configured to control the bidirectional gas delivery unit (201) to generate a periodic negative pressure pulse, and to control the cutting particle adding and circulating unit to adjust the adding concentration and / or circulation rate of the cutting particles during or after the pulse for 30 seconds to 5 minutes.

5. The operating device according to claim 4, characterized in that The bidirectional gas delivery unit (201) comprises: a positive pressure generating device; a negative pressure generating device; and a switching valve, the gas inlet of the switching valve is connected with the positive pressure generating device and the negative pressure generating device, respectively, the gas outlet of the switching valve is connected with the gas collection end of the membrane module (102), and the switching valve is used to selectively conduct the positive pressure gas path or the negative pressure gas path under the control of the control unit (202).

6. The operating device according to claim 4, characterized by The cutting particle adding and circulating unit comprises: a particle storage tank for storing cutting particles; an adding pump, the inlet of the adding pump is connected with the particle storage tank, and the outlet of the adding pump is connected with the reactor (101); a solid-liquid separation module and a backflow pump, the inlet side of the solid-liquid separation module is connected with the mixed liquid circulating outlet side of the reactor (101), the inlet end of the backflow pump is connected with the solid outlet of the solid-liquid separation module, and the outlet end of the backflow pump is connected with the particle storage tank.

7. The operating device according to claim 4, characterized by The control unit (202) is also electrically connected to: A pressure sensor for monitoring gas pressure inside the membrane, the pressure sensor being disposed at the gas collection end of the membrane module (102); and / or; A water quality analyzer is used to monitor the quality of the effluent, and the water quality analyzer is installed at the outlet of the reactor (101).

8. A sewage treatment system characterised in that, The operating device includes any one of claims 4-7.

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