Batch electrically stimulated biofilm system and method for azo dye removal and denitrification

Abstract

The application discloses a kind of intermittent electric stimulation biofilm system and method for removing azo dye and denitrification, it is related to water treatment technical field, solve the problem such as low removal efficiency of pollutant in azo dye wastewater treatment process.The bioelectrochemical treatment module of the application includes membrane aeration biofilm unit and electrode reinforcement unit, membrane aeration biofilm unit is arranged on the surface of biological anode;Electrode reinforcement unit includes biological anode, biological cathode, power supply and management platform, biological anode, biological cathode are arranged in the inside of reaction container, biological anode and power supply positive pole are connected, biological cathode and power supply negative pole are connected, management platform is built-in machine learning model, to drive the on-off of power supply with real-time water quality monitoring data.The present application realizes the matching of external electron input and microbial electron consumption process by the intermittent electric stimulation regulation strategy driven by machine learning model, improves azo dye reduction and decolorization efficiency, promotes denitrification process, and reduces N2O cumulative emission.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to an intermittently electrically stimulated biofilm system and method for removing azo dyes and denitrifying. Background Technology

[0002] Azo dyes, due to their stable color and diverse structures, are widely used in the textile, printing and dyeing, leather, and paper industries. Currently, azo dyes account for over 60% of global dye production. With the expansion of related industrial production, large quantities of wastewater containing azo dyes and nitrogenous pollutants are discharged into the environment. This type of wastewater typically contains complex aromatic organic compounds, as well as recalcitrant organic and inorganic nitrogen pollutants, exhibiting high biotoxicity, poor biodegradability, and strong environmental persistence. Nitrogenous pollutants, in particular, easily cause eutrophication in water bodies, and the azo bonds and aromatic structures in azo dyes make them difficult to effectively degrade using traditional biological treatment methods, posing a potential threat to the ecological environment and human health.

[0003] Currently, the main methods for treating azo dye wastewater include physical adsorption, chemical oxidation, advanced oxidation, and biological treatment. Among these, biological treatment is widely used in practical wastewater treatment due to its advantages such as low cost, environmental friendliness, and stable operation. However, in the process of simultaneously removing azo dyes and nitrogen pollutants, both the azo bond reduction reaction and the denitrification process require electron donors. An electron competition relationship exists between the two processes, leading to reduced electron transfer efficiency and limiting the simultaneous removal of pollutants. Furthermore, insufficient electron donors can easily cause incomplete denitrification, resulting in the accumulation of the intermediate product nitrous oxide (N2O). As a highly efficient greenhouse gas, the emission control of N2O has become a crucial issue for achieving low-carbon development in wastewater treatment processes.

[0004] Membrane-aerated biofilm reactors (MABRs) are a novel biofilm treatment technology. They utilize membrane oxygenation and reverse diffusion of pollutants to form a unique anti-diffusion biofilm structure, allowing aerobic nitrification and anoxic / anaerobic denitrification zones to coexist within the same biofilm. This promotes organic matter degradation, nitrogen transformation, and the removal of complex pollutants. However, traditional MABR systems primarily rely on the microorganisms' own metabolic processes for electron transfer, resulting in low electron transfer rates and insufficient reduction capacity, making it difficult to meet the demand for simultaneous and efficient removal of azo dyes and nitrogenous pollutants. In recent years, bioelectrochemical systems (BES) have enhanced the redox capacity of pollutants by regulating the extracellular electron transfer process of microorganisms through electrodes. However, continuous electrical stimulation requires a continuous input of electrical energy, increasing operating costs. Furthermore, long-term electrical stimulation may cause electrochemical stress, affecting microbial activity and functional stability. Intermittent electrical stimulation, through periodic on / off cycles, can utilize the electron storage and release characteristics of electroactive biofilms to dynamically regulate electron supply and reduce the adverse effects of continuous stimulation. However, existing intermittent electrical stimulation typically uses a fixed on / off cycle, which cannot dynamically adjust the electron input according to changes in the redox state of the reaction system. This may lead to an imbalance between electron supply and demand, limiting the long-term stable operation of the system.

[0005] Therefore, current technologies still lack an intelligent enhanced treatment system that can simultaneously meet the requirements of efficient removal of azo dyes, simultaneous conversion of nitrogen pollutants, and low-carbon operation. Developing a wastewater treatment method based on redox state feedback to regulate intermittent electrical stimulation parameters, improve electron utilization efficiency, enhance microbial metabolic regulation capabilities, and reduce N2O emissions is of great significance for achieving efficient, stable, and low-energy treatment of recalcitrant dye wastewater. Summary of the Invention

[0006] To address the aforementioned problems in existing azo dye wastewater treatment processes, such as low pollutant removal efficiency, severe competition for electron donors, easy generation of nitrous oxide (N2O) during denitrification, and high energy consumption of traditional bioelectrochemical enhancement technologies, this invention proposes an intermittent electrostimulation biofilm system and method for removing azo dyes and performing denitrification. This invention combines membrane aeration biofilm reaction technology with bioelectrochemical enhancement technology, dynamically adjusting the energizing and de-energizing times based on ORP changes. This achieves a match between external electron input and microbial electron consumption, improving electron utilization efficiency, increasing the reduction and decolorization efficiency of azo dyes, promoting nitrogen conversion, and reducing cumulative N2O emissions.

[0007] This invention proposes an intermittent electrostimulation biofilm system for removing azo dyes and denitrifying, specifically comprising a management platform, a reaction vessel, a bioelectrochemical treatment module, an intermittent electrostimulation control module, and a gas supply structure; the management platform and the intermittent electrostimulation control module are connected; the bioelectrochemical treatment module includes a membrane aeration biofilm unit and an electrode enhancement unit, the electrode enhancement unit including a bioanode, a biocathode, and a power source, the bioanode and biocathode being disposed inside the reaction vessel, the bioanode being connected to the positive terminal of the power source, and the biocathode being connected to the negative terminal of the power source, the membrane aeration biofilm unit being disposed on the surface of the bioanode; the gas supply structure is connected to the bioanode; the intermittent electrostimulation control module is connected to the power source and controls the on / off state of the power source according to instructions.

[0008] Furthermore, the membrane aeration biofilm unit includes a membrane aeration component and a functional microbial biofilm attached to the membrane aeration component.

[0009] Furthermore, the membrane aeration assembly includes one or more of hollow fiber membranes, flat sheet membranes, and tubular membranes; the membrane material is polyvinylidene fluoride, polytetrafluoroethylene, or polypropylene.

[0010] Furthermore, the intermittent electrical stimulation control module includes a PLC controller and a relay. The PLC controller receives intermittent electrical stimulation control parameters generated based on a machine learning model from the management platform, and controls the on / off state of the relay according to the control parameters to achieve dynamic adjustment of the power supply on / off time.

[0011] Furthermore, the reaction vessel is equipped with a redox potential meter, which is used to monitor the changes in the system's ORP in real time and transmits the real-time ORP data to the management platform as an input signal for the machine learning model.

[0012] Furthermore, it also includes an online water quality testing module, which is connected to the management platform and the oxidation-reduction potential meter respectively, to collect ORP data, and transmit the collected multi-source data as multi-dimensional input features to the machine learning model of the management platform.

[0013] Furthermore, it also includes an inlet water tank and an outlet water tank, both of which are connected to the reaction vessel; an inlet peristaltic pump is installed between the inlet water tank and the reaction vessel; an outlet peristaltic pump is installed between the outlet water tank and the reaction vessel; an online water quality detection module is connected to the outlet water tank to collect outlet water quality parameters and transmit the collected multi-source data as multi-dimensional input features to the machine learning model of the management platform.

[0014] Furthermore, the management platform has a pre-trained machine learning model built in. This model takes the ORP data and effluent water quality parameters collected in real time by the online water quality detection module as input and outputs intermittent electrical stimulation control parameters for adjusting the power supply.

[0015] Furthermore, the management platform includes a data acquisition unit, a data storage unit, a model training and update unit, an operational status prediction unit, a control strategy generation unit, and an instruction output unit. The data acquisition unit receives real-time ORP data and effluent water quality parameters uploaded by the online water quality monitoring module. The data storage unit stores historical ORP data, historical water quality parameters, and corresponding historical electrical stimulation operational parameters to construct a training dataset. The model training and update unit incorporates a machine learning model, which is a feedforward neural network containing an input layer, hidden layers, and an output layer. The input layer uses ORP values, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, total nitrogen, and color as input parameters. The hidden layer extracts high-dimensional correlations between each feature and the optimal electrical stimulation parameters, while the output layer outputs the power-on and power-off times. The machine learning model is trained and iteratively updated using historical operating data as the training set and with the optimization objective of achieving effluent water quality standards and minimizing energy consumption. The operating state prediction unit is used to input the current ORP and water quality parameters into the trained model to predict the changing trends of the system's electron supply and demand states. The control strategy generation unit is used to generate intermittent electrical stimulation control parameters based on the prediction results, so that the power-on and power-off durations match the predicted microbial electron consumption and storage cycles. The instruction output unit is used to output the control parameters to the power supply via the PLC controller and relays to control the power supply on and off.

[0016] A method of using the above-described intermittent electrical stimulation biomembrane system for removing azo dyes and denitrifying includes the following steps: Step 1: Construct a membrane aeration biofilm unit, inoculate with functional microorganisms, and form a biofilm; Step 2: Input the wastewater to be treated into the reaction vessel to form a reverse diffusion biofilm structure under membrane aeration conditions; Step 3: Activate the online water quality monitoring module to monitor the system's ORP data and effluent water quality parameters in real time; Step 4: The data acquisition unit of the management platform receives the multi-source data collected in Step 3, the data storage unit saves historical data and constructs a training dataset, and the model training and update unit uses the training dataset to train the machine learning model and establish a mapping relationship between ORP change trends, water quality parameters and optimal electrical stimulation parameters. Step 5: The operating status prediction unit inputs the current real-time ORP data and water quality parameters into the trained machine learning model to predict the trend of electronic supply and demand changes in the system over a future period. Step 6: The control strategy generation unit automatically generates intermittent electrical stimulation control parameters, including energizing time and de-energizing time values, based on the predicted trend of the change in the electron supply and demand state. Step 7: The instruction output unit outputs the intermittent electrical stimulation control parameters to the intermittent electrical stimulation control module. The PLC controller controls the relay to turn on and off according to the control parameters, and automatically adjusts the power-on and power-off times. This enables the system to promote electronic input and storage during the power-on phase, and to continuously drive the reduction of azo dyes and nitrogen conversion during the power-off phase by utilizing the stored electrons, thereby achieving dynamic matching between external electronic input and microbial electronic consumption processes.

[0017] The beneficial effects of the intermittent electrical stimulation biomembrane system and method for removing azo dyes and denitrifying as described in this invention are as follows: (1) The intermittent electrostimulation biofilm system and method for removing azo dyes and denitrification described in this invention combines membrane aeration biofilm technology with bioelectrochemical enhancement technology. By utilizing the spatial redox gradient formed by the reverse diffusion biofilm, aerobic nitrification, anoxic denitrification and azo dye reduction processes are carried out synergistically in the same system, thereby improving the ability to remove pollutants simultaneously from complex dye wastewater.

[0018] (2) The intermittent electrical stimulation biofilm system and method for removing azo dyes and denitrification described in this invention adopts an intermittent electrical stimulation method based on ORP feedback regulation. Compared with the traditional continuous electrical stimulation mode, the electron input intensity can be dynamically adjusted according to the actual redox state of the reaction system, avoiding insufficient or excessive electron supply caused by fixed operation mode, and improving the energy utilization efficiency.

[0019] (3) The intermittent electrostimulation biofilm system and method for removing azo dyes and denitrification described in this invention utilizes the electron storage and release characteristics of electroactive biofilms to maintain the pollutant reduction process during the power-off phase, realize the dynamic balance between external electron input and microbial electron utilization process, enhance the azo bond reduction and breaking ability in azo dyes, and promote complete nitrogen conversion.

[0020] (4) The intermittent electrostimulation biofilm system and method for removing azo dyes and denitrification described in this invention optimizes the electron transfer process and nitrogen conversion pathway of the biofilm, which helps to reduce electron competition in the denitrification process, improve the integrity of denitrification, and reduce the generation and accumulation of N2O.

[0021] (5) The intermittent electrical stimulation biofilm system and method for removing azo dyes and denitrification described in this invention has a simple system structure and flexible operation mode. It can realize intelligent adjustment of intermittent electrical stimulation parameters through online monitoring and automatic control, and can adapt to the wastewater treatment needs under different pollution load conditions. It is suitable for the treatment of azo dye and nitrogen-containing wastewater generated by textile printing and dyeing, chemical and other industries, and has good engineering application prospects. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] In the attached diagram: Figure 1 This is a schematic diagram of the structure of an intermittently electrically stimulated biomembrane system for removing azo dyes and denitrifying, as described in this invention. Figure 2 This invention relates to an intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying NH4 under three conditions: no electrostimulation system, continuous electrostimulation system, and intermittent electrostimulation system. + The removal effect of -N; Figure 3 This invention relates to an intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying NO2 under three conditions: no electrostimulation system, continuous electrostimulation system, and intermittent electrostimulation system. - The removal effect of -N; Figure 4 This invention relates to an intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying NO3 under three conditions: no electrostimulation system, continuous electrostimulation system, and intermittent electrostimulation system. - The removal effect of -N; Figure 5 The present invention describes the removal effect of an intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying on Alizarin Yellow R under non-electrostimulation, continuous electrostimulation, and intermittent electrostimulation systems. Figure 6 This invention describes the N2O removal efficiency of an intermittent electrostimulation biofilm system for removing azo dyes and denitrifying under three conditions: no electrostimulation system, continuous electrostimulation system, and intermittent electrostimulation system. Figure 7 This invention describes the removal efficiency of an intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying under three conditions: no electrostimulation system, continuous electrostimulation system, and intermittent electrostimulation system. Figure 8This invention describes the capacitance characteristics of an intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying under non-electrostimulation, continuous electrostimulation, and intermittent electrostimulation conditions. The components are: 1-Management platform, 2-PLC controller, 3-Online water quality testing module, 4-Inlet water tank, 5-Outlet water tank, 6-Gas cylinder, 7-Relay, 8-Power supply, 9-Biological anode, 10-Biological cathode, 11-Oxidation-reduction potential analyzer, 12-Inlet peristaltic pump, 13-Outlet peristaltic pump. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. The described embodiments are merely some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Specific implementation method one: See Figures 1-8 This embodiment is described in detail. The intermittent electrostimulation biofilm system for removing azo dyes and denitrifying, as described in this embodiment, specifically includes a management platform 1, an online water quality monitoring module 3, a reaction vessel, a bioelectrochemical treatment module, an intermittent electrostimulation control module, an inlet water tank 4, an outlet water tank 5, and an air supply structure. Both the inlet water tank 4 and the outlet water tank 5 are connected to the reaction vessel; an inlet peristaltic pump 12 is installed between the inlet water tank 4 and the reaction vessel; an outlet peristaltic pump 13 is installed between the outlet water tank 5 and the reaction vessel; and the outlet water tank 5 is connected to the online water quality monitoring module 3.

[0026] The bioelectrochemical treatment module includes a membrane aeration biofilm unit and an electrode enhancement unit. The membrane aeration biofilm unit is used to form a reverse diffusion biofilm structure with an oxygen concentration gradient, realizing pollutant mass transfer, biodegradation, and nitrogen conversion processes. The electrode enhancement unit includes a bioanode 9, a biocathode 10, and a power source 8, used to create an electrochemically driven environment within the biofilm system to promote the extracellular electron transfer process of microorganisms. The bioanode 9 and biocathode 10 are located inside the reaction vessel. The bioanode 9 is connected to the positive terminal of the power source 8, and the biocathode 10 is connected to the negative terminal of the power source 8. The membrane aeration biofilm unit is located on the surface of the bioanode 9. The gas supply structure is a gas cylinder 6, which is connected to the bioanode 9. The extracellular electron transfer process of microorganisms is promoted by the action of an external electric field, improving the electron transport capacity of the biofilm and providing electronic driving force for the reduction and breakage of azo bonds in azo dyes and the conversion of nitrogen-containing pollutants.

[0027] The membrane aeration biofilm unit includes a membrane aeration component and a functional microbial biofilm attached to the membrane aeration component. Oxygen is supplied to the interior of the biofilm through the membrane aeration component, and the reverse diffusion of pollutants from the liquid phase to the interior of the biofilm forms a reverse diffusion biofilm structure with an oxygen concentration gradient. This allows aerobic nitrifying microorganisms, anoxic denitrifying microorganisms, and functional microorganisms capable of degrading azo dyes to work synergistically in different spatial regions, achieving organic matter degradation, nitrogen conversion, and azo dye reduction processes. The membrane aeration component includes one or more of hollow fiber membranes, flat sheet membranes, and tubular membranes; the membrane material is polyvinylidene fluoride, polytetrafluoroethylene, or polypropylene. A bioanode 9 is coupled to the membrane aeration component, and a biocathode 10 is located in the non-aeration area. The electrochemical interaction between the bioanode 9 and the biocathode 10 creates a bioelectrochemically enhanced environment with a redox gradient.

[0028] The management platform 1 is connected to both the intermittent electrical stimulation control module and the online water quality monitoring module 3. It receives, stores, and analyzes online monitoring data, analyzes the system's operating status based on the monitoring data, outputs control commands, and sends control commands to the intermittent electrical stimulation control module. The management platform 1 includes a data acquisition unit, a data storage unit, a model training and update unit, an operating status prediction unit, a control strategy generation unit, and a command output unit. The data acquisition unit receives ORP data uploaded by the online water quality monitoring module 3. The data storage unit stores historical operating data. The model training and update unit incorporates a feedforward neural network model. This model takes ORP value, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, total nitrogen, and color as inputs, and outputs energization and de-energization times. It is trained using historical data as training samples and with the optimization objective of achieving effluent standards and minimizing energy consumption, enabling the model to capture the mapping relationship between water quality fluctuations and optimal electrical stimulation parameters. The operating status prediction unit inputs the current measured data into the trained model to predict the direction of change in the system's electronic supply and demand situation in the next stage. The control strategy generation unit sets the energization and de-energization times based on the above prediction results. The instruction output unit outputs the generated control parameters to the power supply 8 via PLC controller 2 and relay 7 to perform on / off switching.

[0029] The machine learning model built into the management platform 1 adopts a feedforward neural network structure, including an input layer, at least one hidden layer, and an output layer. The input layer has 6 nodes, corresponding to six water quality parameters: ORP value, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, total nitrogen, and color. The hidden layer preferably has 12 nodes, and the activation function is ReLU (Rectified Linear Unit), used to perform nonlinear mapping on the input features and extract high-dimensional correlation features between each input feature and the optimal electrical stimulation parameters. The output layer has 2 nodes, corresponding to the power-on time T_on and the power-off time T_off. The training set of the machine learning model comes from historical operating data stored in the data storage unit, including historical ORP data, historical water quality parameters, and corresponding historical electrical stimulation operating parameters. Model training aims to achieve effluent water quality standards while minimizing unit energy consumption. The Adam optimization algorithm is used for training, with an initial learning rate of 0.001 and 1000 training epochs until the loss function converges. After training, the model outputs the optimal power-on and power-off times that achieve dynamic balance between electron supply and microbial electron consumption under the current state, based on the ORP value and water quality parameters input in real time by the online water quality detection module 3. The control parameters are then output to the power supply 8 via the PLC controller 2 and the relay 7.

[0030] It should be noted that the structural parameters of the above neural network (such as the number of hidden layer nodes, activation function, optimization algorithm and learning rate, etc.) are only illustrative examples. Those skilled in the art can make appropriate adjustments according to the actual wastewater treatment scale, water quality characteristics and treatment requirements. These adjustments are all reasonable variations of the content disclosed in this invention.

[0031] The reaction vessel is equipped with an oxidation-reduction potential (ORP) meter 11, which is connected to an online water quality monitoring module 3. The online water quality monitoring module 3 is used to acquire real-time ORP information and effluent water quality parameters during the treatment process, and transmits the monitoring data to the management platform 1. The management platform 1 determines the electron supply and demand status of the bioelectrochemical treatment system based on the ORP change trend and dynamically adjusts the on-time and off-time during intermittent electrical stimulation to maintain a suitable oxidation-reduction environment. When the ORP reaches a preset threshold range, the system's reduction state is enhanced, and electron demand decreases, the management platform 1 controls the intermittent electrical stimulation control module to enter the off-time phase, allowing the biofilm to continuously reduce and transform pollutants using stored electrons, promoting the release of stored electrons and the pollutant reduction process. When the ORP deviates from the preset range, the system's oxidation-reduction state leans towards an oxidizing environment, and electron supply is insufficient, the management platform 1 controls the system to enter the on-time phase, controlling the intermittent electrical stimulation control module to increase the on-time and improve electron input capability.

[0032] The online water quality testing module 3 also includes an effluent water quality testing unit, which is connected to the effluent water tank 5. The effluent water quality testing unit is used to detect one or more of chemical oxygen demand, ammonia nitrogen, total nitrogen, nitrate nitrogen, nitrite nitrogen, and color, and transmits the test results to the management platform 1.

[0033] The intermittent electrical stimulation control module is used to adjust the power-on and power-off cycles of the power supply 8 according to the control commands output by the management platform 1, so that the bioelectrochemical processing module adjusts the intermittent operating parameters according to the feedback information, thereby realizing the dynamic regulation of the electron input, storage, and release processes. During the power-on phase, the external electric field promotes electron input and the extracellular electron transfer process of microorganisms; during the power-off phase, the electrons stored in the electroactive biomembrane continuously drive the azo dye reduction and nitrogen conversion processes, thereby realizing the dynamic regulation of the electron input, storage, and release processes. The intermittent electrical stimulation control module includes a PLC controller 2 and a relay 7, which are connected sequentially to the power supply 8. The PLC controller 2 receives the control commands output by the management platform 1 and controls the relay 7 to automatically switch the power supply 8 on and off. In this embodiment, the output voltage of the power supply 8 is 0.1–2.0V, preferably 0.5–1.0V.

[0034] A method of using the above-described intermittent electrical stimulation biomembrane system for removing azo dyes and denitrifying includes the following steps: Step 1: Construct a membrane aeration biofilm unit, inoculate it with functional microorganisms that have the ability to degrade azo dyes and denitrify, and form a stable functional biofilm through cultivation and domestication; Step 2: Input the wastewater to be treated into the reaction vessel to form a reverse diffusion biofilm structure with a redox gradient under membrane aeration conditions; Step 3: Activate online water quality monitoring module 3 to monitor system ORP data and effluent water quality parameters in real time; Step 4: The data acquisition unit of management platform 1 receives the multi-source data collected in step 3, the data storage unit saves historical data and constructs a training dataset, and the model training and update unit uses the training dataset to train the machine learning model and establish a mapping relationship between ORP change trend, water quality parameters and optimal electrical stimulation parameters. Step 5: The operating status prediction unit inputs the current real-time ORP data and water quality parameters into the trained machine learning model to predict the trend of electronic supply and demand changes in the system over a future period. Step 6: The control strategy generation unit automatically generates intermittent electrical stimulation control parameters, including energizing time and de-energizing time values, based on the predicted trend of the change in the electron supply and demand state. Step 7: The instruction output unit outputs the intermittent electrical stimulation control parameters to the intermittent electrical stimulation control module. The PLC controller 2 controls the relay 7 to turn on and off according to the control parameters, and automatically adjusts the power-on and power-off times of the power supply 8. This enables the system to promote electronic input and storage during the power-on phase, and to continuously drive the reduction of azo dyes and nitrogen conversion using stored electrons during the power-off phase, thereby achieving dynamic matching between external electronic input and microbial electronic consumption processes.

[0035] The system uses ORP feedback to regulate the intermittent electrical stimulation process, achieving dynamic matching between electron transfer, biological metabolism, and pollutant degradation processes, thereby improving the removal efficiency and denitrification performance of azo dyes and reducing the production of the byproduct nitrous oxide.

[0036] Example 1: A membrane aeration bioelectrochemical reactor was constructed, denoted as the intermittent electrostimulation membrane aeration bioelectrochemical system (MAIEB).

[0037] Domesticated functional microorganisms are inoculated into the reactor and cultured on conductive carriers on the surfaces of bioanode 9 and biocathode 10 to form a stable biofilm. During operation, oxygen diffuses from the inside of the membrane aeration anode assembly to the outside, forming an oxygen concentration gradient that gradually decreases from the membrane side to the liquid phase side within the biofilm. Organic matter, azo dyes, and nitrogenous pollutants in the wastewater diffuse from the bulk liquid phase into the interior of the biofilm, thus forming a reverse diffusion biofilm structure in which oxygen and pollutants diffuse in the opposite direction.

[0038] The membrane aeration anode assembly is connected to the positive terminal of power supply 8, and the cathode assembly is connected to the negative terminal of power supply 8. Power supply 8 achieves periodic power-on and power-off operation through an intermittent electrical stimulation control device. The applied voltage can be adjusted according to the wastewater properties, biofilm status, and treatment requirements, preferably 0.5–1.0 V.

[0039] The system employs an intermittent electrical stimulation operation mode based on ORP feedback control. During operation, the online water quality monitoring module 3 monitors the changes in the oxidation-reduction potential (ORP) of the reaction system in real time and transmits the monitoring data to the management platform 1. The management platform 1 determines the electron supply and demand status of the system based on the ORP change trend and controls the intermittent electrical stimulation control device to automatically adjust the energizing and de-energizing times. When the electron supply of the system is insufficient and the ORP increases, the energizing time is extended to enhance electron input; when the electron storage capacity of the system increases and the ORP decreases to a suitable range, the energizing time is shortened or the system enters the de-energizing phase, allowing the biofilm to continuously drive the azo dye reduction and nitrogen conversion processes using stored electrons. In this embodiment, the system initially operates in an intermittent mode with 12 hours of energizing and 12 hours of de-energizing, and then the energizing time is dynamically adjusted based on the ORP feedback results.

[0040] The reactor can operate in either a sequencing batch or continuous flow mode. In sequencing batch operation, the processes of influent, reaction, sedimentation, and effluent are completed sequentially; the independent sedimentation stage can also be omitted depending on actual needs. During reactor operation, oxygen is continuously supplied through the membrane aeration components, and appropriate stirring is maintained to ensure a uniform mixing state in the reaction system. The oxygen supply intensity, stirring intensity, hydraulic retention time, and operating temperature can be adjusted according to the treatment scale and wastewater properties to ensure stable system operation. After the system stabilizes, the anode biofilm forms a reverse diffusion structure with an oxygen concentration gradient, creating a relatively aerobic region near the membrane side and a relatively anoxic or anaerobic region further away from the membrane side and in the cathode area. The intermittent electrical stimulation, combined with the reverse diffusion biofilm structure, simultaneously enhances the decolorization of azo dyes and the removal of nitrogenous pollutants, reduces system energy consumption, and improves the stability of the treatment process.

[0041] Comparative Example 1: Establish a non-electrically stimulated membrane aeration biofilm system (Control). During system operation, only the membrane aeration and oxygen supply devices are turned on; the external electrical stimulation device is not activated. Oxygen continuously diffuses into the biofilm through the membrane aeration components, forming a stable oxygen concentration gradient on the membrane surface. Azo dyes, organic matter, and nitrogenous pollutants in the wastewater diffuse into the biofilm and undergo pollutant transformation through microbial metabolism.

[0042] This system does not apply an external voltage to the electrodes, and the anode and cathode do not participate in the electrochemical enhancement process. The system mainly relies on the reverse diffusion biofilm structure formed by membrane aeration and the metabolism of functional microorganisms to achieve the degradation and denitrification of azo dyes. The reactor adopts the same oxygen supply method, influent and effluent methods, and operating conditions as in Example 1, and is continuously operated until the system stabilizes before performance testing is conducted to evaluate the treatment effect of the membrane aeration biofilm system under conditions without external electrical stimulation.

[0043] Comparative Example 2: A continuous electrostimulation membrane aeration bioelectrochemical system (MAEB) was constructed, with reactor structure, membrane aeration components, electrode arrangement, oxygen supply method, and biofilm cultivation method all consistent with those in Example 1. After a stable biofilm formed on the anode and cathode surfaces of the membrane aeration system, continuous electrostimulation was initiated.

[0044] During operation, the bioanode 9 is connected to the positive terminal of power supply 8, and the biocathode 10 is connected to the negative terminal of power supply 8. Power supply 8 continuously applies electrical stimulation to the reaction system, keeping the electrodes constantly energized without periodic on / off control. The applied voltage can be adjusted according to the wastewater properties and treatment requirements, and remains constant throughout the operation or continuously outputs according to a preset program. Membrane aeration and oxygen supply are continuously provided during reactor operation, maintaining stable mixing to ensure a normal biological treatment environment. The wastewater to be treated enters the reactor continuously or intermittently, completing the degradation of azo dyes and the conversion of nitrogenous pollutants under continuous electrical stimulation. Except for the change from intermittent to continuous power supply, all other operating conditions remain consistent with Example 1.

[0045] Comparative experiments between the examples and the comparative examples: I. Advantages of Intermittent Electrically Stimulated Membrane Aeration System in Pollutant Removal like Figures 2-7 As shown, the effluent water quality was monitored after each system stabilized. The effluent NH4 levels were monitored for the non-electrostimulation system (Control), the continuous electrostimulation system (MAEB), and the intermittent electrostimulation system (MAIEB). + The concentrations of NO2- were 3.16 ± 0.27, 2.73 ± 0.32, and 2.35 ± 0.35 mg / L, respectively, indicating that external electrical stimulation was beneficial in reducing the ammonia nitrogen concentration in the effluent. The intermittent electrical stimulation system showed better ammonia nitrogen removal efficiency. NO2 in the three systems... - The concentrations of -N in the effluent were 2.36 ± 0.34, 1.11 ± 0.36, and 0.75 ± 0.42 mg / L, with the intermittent electrical stimulation system showing the lowest nitrite nitrogen accumulation. - -N represents the main nitrogen form in the effluent of each system. The effluent concentration of the intermittent electrical stimulation system was 2.65 ± 0.56 and 0.45 ± 0.23 mg / L lower than that of the Control group and MAEB group, respectively, indicating that intermittent electrical stimulation can further promote nitrogen conversion in the system. The total nitrogen (TN) in the effluent of the three systems were 17.48 ± 2.05, 13.86 ± 1.17, and 12.35 ± 1.26 mg / L, respectively. The intermittent electrical stimulation system had the lowest total nitrogen concentration, indicating that the intermittent electrical stimulation operation mode can further improve the denitrification effect of the system.

[0046] Alizarin Yellow R (AYR) was used as the target pollutant to evaluate the decolorization performance of the system. The AYR removal rates of the Control group, MAEB group, and MAIEB group were 53.50 ± 4.39%, 76.51 ± 3.11%, and 86.23 ± 2.67%, respectively, with the intermittent electrical stimulation system achieving the highest decolorization efficiency. Simultaneously, the N2O generated during the operation of each system was measured. The N2O accumulation in the Control group, MAEB group, and MAIEB group were 4.17 ± 0.30, 2.67 ± 0.31, and 2.06 ± 0.27 μg / L, respectively. The results indicate that intermittent electrical stimulation can effectively reduce N2O emissions while improving the removal efficiency of azo dyes. This demonstrates that the present invention can achieve synergistic enhancement of azo dye removal and denitrification processes, while also considering greenhouse gas emission reduction effects.

[0047] The overall operational results show that this invention, employing an intermittent electrical stimulation operation mode, organically combines the membrane aeration biofilm structure with the bioelectrochemical enhancement process, achieving dynamic control of electron supply, electron storage, and electron utilization. This system ensures efficient decolorization of azo dyes while improving nitrogen conversion efficiency, and also considers system operational stability and energy utilization efficiency, providing a highly efficient and low-energy-consumption technical solution for the treatment of azo dye wastewater and other nitrogen-containing industrial wastewater.

[0048] II. Regulation of the capacitive properties of biological membranes by intermittent electrical stimulation like Figure 8 As shown, the electrochemical performance of the biofilms formed by the Control system, MAEB system, and MAIEB system was tested, and parameters such as total capacitance and pseudocapacitance were calculated. The test results show that the pseudocapacitances of the Control system, MAEB system, and MAIEB system are 0.16 F, 0.18 F, and 0.26 F, respectively, corresponding to pseudocapacitance accounting for 22.29%, 21.10%, and 30.39% of the total capacitance. Among them, the MAIEB system has the highest pseudocapacitance and pseudocapacitance percentage.

[0049] Pseudocapacitance is used to characterize the reversible storage and release of electrons in biological membranes. The high pseudocapacitance ratio in the MAIEB system indicates that intermittent electrical stimulation can enhance the electron storage capacity of biological membranes and improve the efficiency of electron utilization within the membranes. Figure 2 The pollutant removal results show that the intermittent electrical stimulation operation mode can promote electron storage during the energized phase and its continued participation in the azo dye reduction and nitrogen conversion processes during the de-energized phase, thereby further improving the pollutant removal performance. These results demonstrate that the intermittent electrical stimulation operation mode proposed in this invention can improve the electrochemical activity of the biomembrane, enhance the system's electron transfer capacity, and provide continuous electronic support for the azo dye removal and denitrification processes.

[0050] In summary, this invention combines membrane aeration biofilm technology with an intermittent electrical stimulation strategy to achieve dynamic regulation of the electronic behavior of biofilms, overcoming the limitation of electron utilization efficiency under traditional continuous electrical stimulation modes. The constructed intermittently electrically stimulated membrane aeration bioreactor system has advantages such as high pollutant removal efficiency, high electron utilization rate, good operational stability, and low greenhouse gas emissions, and can be used for the efficient treatment of azo dye wastewater and other wastewater containing recalcitrant organic matter and nitrogenous pollutants.

[0051] In summary, the intermittently electrically stimulated biofilm system and method for removing azo dyes and denitrifying, as described in this invention, combines membrane aeration biofilm technology with bioelectrochemical enhancement technology. By utilizing the spatial redox gradient formed by the reverse diffusion biofilm, aerobic nitrification, anoxic denitrification, and azo dye reduction processes can be carried out synergistically within the same system, thereby improving the simultaneous removal capacity of pollutants in complex dye wastewater.

[0052] The present invention discloses an intermittent electrostimulation biomembrane system and method for removing azo dyes and denitrifying. The intermittent electrostimulation method based on ORP feedback regulation can dynamically adjust the electron input intensity according to the actual redox state of the reaction system compared with the traditional continuous electrostimulation mode, avoiding insufficient or excessive electron supply caused by fixed operation mode, and improving the energy utilization efficiency.

[0053] The present invention discloses an intermittent electrostimulation biofilm system and method for removing azo dyes and denitrifying. It utilizes the electron storage and release characteristics of electroactive biofilms to maintain the pollutant reduction process even during the power-off phase, achieving a dynamic balance between external electron input and microbial electron utilization, enhancing the azo bond reduction and breaking ability in azo dyes, and promoting complete nitrogen conversion.

[0054] The present invention discloses an intermittently electrically stimulated biofilm system and method for removing azo dyes and denitrifying. By optimizing the electron transfer process and nitrogen conversion pathway of the biofilm, it is beneficial to reduce electron competition in the denitrification process, improve the integrity of denitrification, and reduce the generation and accumulation of N2O.

[0055] The present invention discloses an intermittent electrostimulation biofilm system and method for removing azo dyes and denitrifying. The system has a simple structure and flexible operation mode. Through online monitoring and automatic control, the intermittent electrostimulation parameters can be intelligently adjusted, which can adapt to the wastewater treatment needs under different pollution load conditions. It is suitable for the treatment of azo dye and nitrogen-containing wastewater generated by industries such as textile printing and dyeing and chemical industry, and has good engineering application prospects.

[0056] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the invention. They can also be reasonable combinations of the features described in the above embodiments. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An intermittently electrically stimulated biomembrane system for removing azo dyes and denitrifying, characterized in that: It includes a management platform (1), a reaction vessel, a bioelectrochemical treatment module, an intermittent electrical stimulation control module, and a gas supply structure; the management platform (1) and the intermittent electrical stimulation control module are connected; the bioelectrochemical treatment module includes a membrane aeration biofilm unit and an electrode enhancement unit, the electrode enhancement unit includes a bioanode (9), a biocathode (10), and a power source (8), the bioanode (9) and the biocathode (10) are located inside the reaction vessel, the bioanode (9) is connected to the positive terminal of the power source (8), the biocathode (10) is connected to the negative terminal of the power source (8), the membrane aeration biofilm unit is located on the surface of the bioanode (9); the gas supply structure is connected to the bioanode (9); the intermittent electrical stimulation control module is connected to the power source (8) and controls the on / off state of the power source (8) according to the instructions.

2. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 1, characterized in that: The membrane aeration biofilm unit includes a membrane aeration component and a functional microbial biofilm attached to the membrane aeration component.

3. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 2, characterized in that: The membrane aeration component includes one or more of hollow fiber membranes, flat sheet membranes, and tubular membranes; the membrane material is polyvinylidene fluoride, polytetrafluoroethylene, or polypropylene.

4. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 1, characterized in that: The intermittent electrical stimulation control module includes a PLC controller (2) and a relay (7). The PLC controller (2) receives intermittent electrical stimulation control parameters generated based on a machine learning model from the management platform (1), and controls the on / off state of the relay (7) according to the control parameters to achieve dynamic adjustment of the power supply (8) power-on time and power-off time.

5. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 4, characterized in that: The reaction vessel is equipped with an oxidation-reduction potential meter (11), which is used to monitor the changes in the system's ORP in real time and transmit the real-time ORP data as the input signal of the machine learning model to the management platform (1).

6. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 5, characterized in that: It also includes an online water quality detection module (3), which is connected to the management platform (1) and the oxidation-reduction potential meter (11) respectively, for collecting ORP data, and transmitting the collected multi-source data as multi-dimensional input features to the machine learning model of the management platform (1).

7. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 6, characterized in that: It also includes an inlet water tank (4) and an outlet water tank (5), both of which are connected to the reaction vessel; an inlet peristaltic pump (12) is installed between the inlet water tank (4) and the reaction vessel; an outlet peristaltic pump (13) is installed between the outlet water tank (5) and the reaction vessel; the online water quality detection module (3) is connected to the outlet water tank (5) to collect the outlet water quality parameters and transmit the collected multi-source data as multi-dimensional input features to the machine learning model of the management platform (1).

8. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 6, characterized in that: The management platform (1) has a pre-trained machine learning model built in. The model takes the ORP data and effluent water quality parameters collected in real time by the online water quality detection module (3) as input and outputs intermittent electrical stimulation control parameters for adjusting the on / off state of the power supply (8).

9. The intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying according to claim 8, characterized in that: The management platform (1) includes a data acquisition unit, a data storage unit, a model training and update unit, an operation status prediction unit, a control strategy generation unit, and an instruction output unit. The data acquisition unit is used to receive real-time ORP data and effluent water quality parameters uploaded by the online water quality detection module (3). The data storage unit is used to save historical ORP data, historical water quality parameters, and corresponding historical electrical stimulation operation parameters to construct a training dataset. The model training and update unit has a built-in machine learning model, which is a feedforward neural network containing an input layer, a hidden layer, and an output layer. The input layer uses ORP value, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, total nitrogen, and chromaticity as input features. The hidden layer extracts the high-dimensional correlation between each feature and the optimal electrical stimulation parameters. The output layer outputs the power-on time and power-off time. The machine learning model is trained and iteratively updated using historical operating data as the training set and with the goal of achieving the standard of effluent water quality and the lowest energy consumption. The operating status prediction unit is used to input the current ORP and water quality parameters into the trained model to predict the trend of electron supply and demand in the system. The control strategy generation unit is used to generate intermittent electrical stimulation control parameters based on the prediction results, so that the power on / off duration matches the predicted microbial electron consumption and storage cycle. The instruction output unit is used to output the control parameters to the power supply (8) via the PLC controller (2) and the relay (7) to control the power supply (8) to switch on and off.

10. A method of using the intermittent electrostimulation biomembrane system for removing azo dyes and denitrifying as described in claim 9, characterized in that: Includes the following steps: Step 1: Construct a membrane aeration biofilm unit, inoculate with functional microorganisms, and form a biofilm; Step 2: Input the wastewater to be treated into the reaction vessel to form a reverse diffusion biofilm structure under membrane aeration conditions; Step 3: Start the online water quality monitoring module (3) to monitor the system ORP data and effluent water quality parameters in real time; Step 4: The data acquisition unit of the management platform (1) receives the multi-source data collected in Step 3, the data storage unit saves historical data and constructs a training dataset, and the model training and update unit uses the training dataset to train the machine learning model and establishes the mapping relationship between ORP change trend, water quality parameters and optimal electrical stimulation parameters. Step 5: The operating status prediction unit inputs the current real-time ORP data and water quality parameters into the trained machine learning model to predict the trend of electronic supply and demand changes in the system over a future period. Step 6: The control strategy generation unit automatically generates intermittent electrical stimulation control parameters, including energizing time and de-energizing time values, based on the predicted trend of the change in the electron supply and demand state. Step 7: The instruction output unit outputs the intermittent electrical stimulation control parameters to the intermittent electrical stimulation control module. The PLC controller (2) controls the relay (7) to turn on and off according to the control parameters, and automatically adjusts the power-on time and power-off time of the power supply (8). The system promotes electron input and storage during the power-on phase, and utilizes the stored electrons to continuously drive the reduction of azo dyes and nitrogen conversion during the power-off phase, thereby achieving dynamic matching between external electron input and microbial electron consumption processes.

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