Anaerobic fermentation system and method for organic-rich wastewater based on photoelectrochemistry

Abstract

The application discloses an anaerobic fermentation system and method for organic matter-rich wastewater based on photoelectrochemistry, and the system comprises a hydrolysis-acid-producing tank, a methane-producing tank and an intelligent monitoring device; a first gas outlet branch pipe is connected to the hydrolysis-acid-producing tank; the first gas outlet branch pipe is communicated with a gas outlet main pipe; the gas outlet main pipe is connected to the methane-producing tank and a gas collecting tank; a first liquid outlet branch pipe is connected to the bottom plate of the hydrolysis-acid-producing tank; the first liquid outlet branch pipe is communicated with a liquid outlet main pipe; the liquid outlet main pipe is connected to the methane-producing tank; a first liquid inlet branch pipe is communicated with the methane-producing tank; a delivery pump is arranged on the liquid outlet main pipe; first and second photoelectrochemical integrated devices are arranged on the inner walls of the hydrolysis-acid-producing tank and the methane-producing tank respectively; and first and second stirring devices are arranged in the hydrolysis-acid-producing tank and the methane-producing tank respectively. The application can greatly improve the treatment efficiency and effect of the organic matter-rich wastewater, and effectively solves the technical problems of low treatment efficiency and poor treatment effect of the prior treatment methods.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering and renewable energy technology, specifically relating to an anaerobic fermentation system and method for organic-rich wastewater based on photoelectrochemistry. Background Technology

[0002] Wastewater rich in organic matter refers to wastewater that mainly contains high concentrations of complex organic compounds such as carbohydrates, proteins, and fats. Its main sources include kitchen wastewater, agricultural and livestock wastewater, and other organic-rich wastewater. Improper treatment of this type of wastewater not only wastes resources but also easily leads to serious environmental pollution problems.

[0003] Currently, physicochemical methods are mainly used to treat organic-rich wastewater. The aim is to recover useful components from the wastewater or treat some recalcitrant substances, thereby removing harmful substances, improving resource utilization, and reducing environmental pollution. Commonly used physicochemical methods include extraction, adsorption, concentration, and ultrasonic degradation. Problems with these wastewater treatment methods mainly include low treatment efficiency, difficulty in degrading some organic matter, high treatment costs, and secondary pollution. Traditional anaerobic fermentation technology is also used to treat organic-rich wastewater, but it suffers from long process cycles, high investment and operating costs, low treatment efficiency, and poor treatment effects. Therefore, a photoelectrochemical-based anaerobic fermentation system and method for treating organic-rich wastewater is needed, which offers high treatment efficiency, good treatment effects, and low cost. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an anaerobic fermentation system and method for organic-rich wastewater based on photoelectrochemistry, integrating a microbial fuel cell, a microbial electrolyzer, a photochemical device, photoelectrochemical materials, and an intelligent monitoring device, to achieve efficient anaerobic fermentation of organic-rich wastewater to produce methane.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] An anaerobic fermentation system for organic-rich wastewater based on photoelectrochemistry includes a hydrolysis acid-producing tank, a methanogenic tank, and an intelligent monitoring device. The top cover of the hydrolysis acid-producing tank is connected to a first gas outlet branch pipe via a first gas outlet. The first gas outlet branch pipe is connected to a main gas outlet pipe. The main gas outlet pipe is connected to the methanogenic tank via a second gas outlet branch pipe. The main gas outlet pipe is connected to a gas collection tank via a third gas outlet branch pipe. The second gas outlet branch pipe is connected to the methanogenic tank via a second gas outlet. A first gas outlet valve is installed on the first gas outlet branch pipe. A second gas outlet valve is installed on the second gas outlet branch pipe. A third gas outlet valve is installed on the third gas outlet branch pipe.

[0007] The bottom plate of the hydrolysis acid production tank is connected to a first liquid outlet branch pipe through a first liquid outlet. The first liquid outlet branch pipe is connected to the liquid outlet main pipe. The liquid outlet main pipe is connected to the methanogenic tank through a first liquid inlet branch pipe. The first liquid inlet branch pipe is connected to the methanogenic tank through a first liquid inlet. A transfer pump is installed on the liquid outlet main pipe. The liquid produced in the hydrolysis acid production tank flows into the first liquid outlet branch pipe through the first liquid outlet and then into the liquid outlet main pipe. The transfer pump pumps the liquid in the liquid outlet main pipe through the first liquid inlet branch pipe and the first liquid inlet to the methanogenic tank for the next fermentation step.

[0008] The hydrolysis acid production tank is equipped with a main feed inlet and a first auxiliary feed inlet. A first photoelectrochemical integrated device is installed on the inner wall of the hydrolysis acid production tank, and a first stirring device is installed inside the hydrolysis acid production tank. The methan production tank is equipped with a second auxiliary feed inlet. A second photoelectrochemical integrated device is installed on the inner wall of the methan production tank, and a second stirring device is installed inside the methan production tank.

[0009] The top cover of the hydrolysis acid production tank is connected to a first water inlet branch pipe through a first water inlet. The first water inlet branch pipe is connected to the main water inlet pipe. The main water inlet pipe is connected to the methan production tank through a second water inlet branch pipe. The main water inlet pipe is connected to the water storage tank through a third water inlet branch pipe. A water pump is installed in the water storage tank.

[0010] The first water inlet branch pipe is equipped with a first water inlet valve, the second water inlet branch pipe is equipped with a second water inlet valve, and the third water inlet branch pipe is equipped with a third water inlet valve;

[0011] Both the bottom of the hydrolysis acid production tank and the bottom of the methan production tank are equipped with slag outlets, and slag outlets are connected to slag outlets. Water pumps send water from the water storage tank to the hydrolysis acid production tank and the methan production tank for cleaning. The wastewater after cleaning is discharged through the slag outlet and slag outlet.

[0012] The first photoelectrochemical integrated device includes a first integrated plate vertically installed on the inner wall of the hydrolysis acid production tank. The first integrated plate is provided with a first photochemical mounting groove. The upper and lower sides of the first photochemical mounting groove are respectively provided with a first electrochemical upper mounting groove and a first electrochemical lower mounting groove. A first electrochemical device is installed in both the first electrochemical upper mounting groove and the first electrochemical lower mounting groove. The first photochemical device is installed in the first photochemical mounting groove.

[0013] The second photoelectrochemical integrated device includes a second integrated plate vertically installed on the inner wall of the methanogenic tank. The second integrated plate is provided with a second photochemical mounting groove. The upper and lower sides of the second photochemical mounting groove are respectively provided with a second electrochemical upper mounting groove and a second electrochemical lower mounting groove. A second electrochemical device is installed in both the second electrochemical upper mounting groove and the second electrochemical lower mounting groove. The second photochemical device is installed in the second photochemical mounting groove.

[0014] The first electrochemical device includes a microbial fuel cell, and the second electrochemical device includes a microbial electrolysis cell. A first wire hole is provided on the top cover of the hydrolysis acid production tank, and a second wire hole is provided on the methanation production tank. A first wire is connected to the microbial fuel cell, and a second wire is connected to the microbial electrolysis cell. The first wire and the second wire pass through the first wire hole and the second wire hole respectively and are connected in series. A voltage regulator and an external power supply are also connected at the same time.

[0015] Both the anode and cathode of the microbial fuel cell and the microbial electrolyzer are made of carbon cloth material, and the surfaces of the anode of the microbial fuel cell and the cathode of the microbial electrolyzer are roughened. The surfaces of the cathode of the microbial fuel cell and the anode of the microbial electrolyzer are covered with hematite catalyst film. Both the anode and cathode of the microbial fuel cell and the microbial electrolyzer are arranged in parallel, and the first integrated plate and the second integrated plate are both made of insulating material.

[0016] Both the first and second electrochemical devices include a microbial electrolysis cell. The top cover of the hydrolysis acid-producing tank is provided with a first wire hole, and the methanogenic tank is provided with a second wire hole. The microbial electrolysis cell of the hydrolysis acid-producing tank is connected to a first wire, and the microbial electrolysis cell of the methanogenic tank is connected to a second wire. The microbial electrolysis cells of the hydrolysis acid-producing tank and the microbial electrolysis cells of the methanogenic tank are connected in parallel through the first and second wires and are simultaneously connected to an external power source.

[0017] The anode of the microbial fuel cell is installed in the first electrochemical upper installation tank, the cathode of the microbial fuel cell is installed in the first electrochemical lower installation tank, the cathode of the microbial electrolysis cell is installed in the second electrochemical upper installation tank, and the anode of the microbial electrolysis cell is installed in the second electrochemical lower installation tank.

[0018] The first photochemical device includes a first LED light strip, and the second photochemical device includes a second LED light strip. Both the first and second LED light strips are insulated light strips. The first LED light strip is a blue-green LED light, and the second LED light strip is a white LED light. The first LED light strip is installed in the first photochemical mounting tank, which is located between the anode and cathode of the microbial fuel cell. The second LED light strip is installed in the second photochemical mounting tank, which is located between the cathode and anode of the microbial electrolysis cell.

[0019] Intelligent monitoring devices include:

[0020] The control module, including a PLC controller, is used for data analysis and calculation, and establishes a predictive model based on the analysis results to predict the optimal fermentation environment, and then sends control commands to the execution module.

[0021] The execution module is used to receive control commands sent by the control module and precisely adjust the voltage of each valve and lamp strip according to the control commands. It includes a temperature regulator, a pH regulator, a stirring speed regulator, and a stirring time regulator.

[0022] The sensor module includes several types of sensors used to collect environmental data inside the hydrolysis acid production tank and methanation tank, and transmit the measured data to the control module and cloud storage module.

[0023] The cloud storage module is used to receive data measured by the sensor module, preprocess the data, and back up and store the data.

[0024] The remote visual monitoring module includes at least one user interface, allowing users to remotely access the system via the Internet and monitor and control the fermentation process through icons and control panels.

[0025] The fermentation method of the above-mentioned anaerobic fermentation system for organic-rich wastewater based on photoelectrochemistry includes the following steps:

[0026] (1) Add the pretreated organic wastewater to the hydrolysis acid production tank;

[0027] (2) Add the first photoelectrochemical material into the hydrolysis acid production tank, start the first photoelectrochemical integrated device, adjust the voltage and current of the first electrochemical device, and start the first stirring device;

[0028] (3) The intelligent monitoring device automatically monitors the gas content in the hydrolysis acid production tank. When the gas content meets the requirements of the second stage, the intelligent monitoring device controls the first and second gas outlet valves to open, so that the gas in the hydrolysis acid production tank enters the methan production tank. When the gas is excessive, the intelligent monitoring device controls the second gas outlet valve to close and the third gas outlet valve to open for gas collection.

[0029] (4) Add the second photoelectrochemical material into the methanogenic tank, start the second photoelectrochemical integrated device, adjust the voltage and current of the second electrochemical device, and start the second stirring device;

[0030] (5) The generated methane is collected and stored through the third outlet branch pipe.

[0031] The first photoelectrochemical material is pretreated hematite. The pretreatment process for hematite is as follows:

[0032] ① Crush the raw hematite ore to a diameter of 0.5–2 mm;

[0033] ② Roast the pulverized hematite sample in air at a temperature of 400–600℃ for 1–2 hours.

[0034] ③ The roasted hematite is soaked in dilute hydrochloric acid for 1 to 2 hours;

[0035] ④ The acid-washed hematite is washed multiple times with a large amount of deionized water until the pH of the wash water is close to neutral, and then dried in hot air at 60-80°C to constant weight for use.

[0036] The second photoelectrochemical material is pretreated zeolite. The pretreatment process for the zeolite is as follows:

[0037] ① Clean the natural or synthetic zeolite to remove surface impurities and dust, and then dry it to remove moisture;

[0038] ② Crush the dried zeolite to a diameter of 0.5–2 mm;

[0039] ③ Soak the crushed zeolite in dilute hydrochloric acid;

[0040] ④ Alkali treatment of zeolite is used to adjust its surface charge properties and improve its compatibility with electrolytes;

[0041] ⑤ The zeolite after chemical treatment is washed multiple times with a large amount of deionized water until the pH of the wash water is close to neutral, and then dried in hot air at 60-80°C to constant weight for use.

[0042] This invention connects a microbial fuel cell and a microbial electrolysis cell in series, enabling anaerobic fermentation to produce high-purity methane, meeting the requirements of green chemistry. It also utilizes the influence of visible light on microbial metabolism to improve the overall fermentation rate. Furthermore, the use of photoelectrochemical materials can significantly modify the reaction environment and increase the reaction rate. In summary, this application is easy to operate, can improve treatment efficiency and effect, and effectively solves the technical problems of existing wastewater treatment methods, such as long process cycles, high investment and operating costs, low treatment efficiency, and poor treatment effect. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the present invention;

[0044] Figure 2 This is a schematic diagram of the structure of the photoelectrochemical integrated device of the present invention;

[0045] Figure 3 This is a schematic diagram of the layout of the photoelectrochemical integrated device of the present invention;

[0046] Figure 4 This is a schematic diagram of the working principle of the first photoelectrochemical integrated device of the present invention;

[0047] Figure 5 This is a flowchart of the process of this invention;

[0048] Figure 6 This is a cross-sectional view of the hydrolysis acid production tank of the present invention. Detailed Implementation

[0049] Example 1

[0050] like Figure 1-6 As shown, the anaerobic fermentation system for organic-rich wastewater based on photoelectrochemistry of the present invention includes a hydrolysis acid-producing tank 1, a methanogenic tank 2, and an intelligent monitoring device 3. The top cover of the hydrolysis acid-producing tank 1 is connected to a first gas outlet branch pipe 4 through a first gas outlet. The first gas outlet branch pipe 4 is connected to a gas outlet main pipe 5. The gas outlet main pipe 5 is connected to the methanogenic tank 2 through a second gas outlet branch pipe 6. The gas outlet main pipe 5 is connected to a gas collection tank through a third gas outlet branch pipe 7. The second gas outlet branch pipe 6 is connected to the methanogenic tank 2 through a second gas outlet. A first gas outlet valve 12 is provided on the first gas outlet branch pipe 4. A second gas outlet valve 13 is provided on the second gas outlet branch pipe 6. A third gas outlet valve 14 is provided on the third gas outlet branch pipe 7.

[0051] A first outlet branch pipe 8 is connected to the bottom plate of the hydrolysis acid production tank 1 through a first outlet port. The first outlet branch pipe 8 is connected to the main outlet pipe 9. The main outlet pipe 9 is connected to the methanogenic tank 2 through a first inlet branch pipe 10. The first inlet branch pipe 10 is connected to the methanogenic tank 2 through a first inlet port. A transfer pump 11 is installed on the main outlet pipe 9. The liquid produced in the hydrolysis acid production tank 1 flows into the first outlet branch pipe 8 through the first outlet port and then into the main outlet pipe 9. The transfer pump 11 pumps the liquid in the main outlet pipe 9 through the first inlet branch pipe 10 and the first inlet port to the methanogenic tank 2 for the next fermentation step.

[0052] The hydrolysis acid production tank 1 is equipped with a main feed inlet 15 and a first auxiliary feed inlet 16. The inner wall of the hydrolysis acid production tank 1 is equipped with a first photoelectrochemical integrated device 17, and the hydrolysis acid production tank 1 is equipped with a first stirring device 19. The methan production tank 2 is equipped with a second auxiliary feed inlet 20. The inner wall of the methan production tank 2 is equipped with a second photoelectrochemical integrated device 18, and the methan production tank 2 is equipped with a second stirring device.

[0053] The top cover of the hydrolysis acid production tank 1 is connected to a first water inlet branch pipe 21 through a first water inlet. The first water inlet branch pipe 21 is connected to the main water inlet pipe 22. The main water inlet pipe 22 is connected to the methan production tank 2 through a second water inlet branch pipe 23. The main water inlet pipe 22 is connected to the water storage tank through a third water inlet branch pipe 24. A water pump is installed in the water storage tank.

[0054] A first inlet valve 25 is installed on the first inlet branch pipe 21, a second inlet valve 26 is installed on the second inlet branch pipe 23, and a third inlet valve 27 is installed on the third inlet branch pipe 24.

[0055] Both the bottom of the hydrolysis acid production tank 1 and the bottom of the methan production tank 2 are equipped with slag outlets, and slag outlets are connected to slag outlets with short slag outlet pipes 28. A water pump sends water from the water storage tank to the hydrolysis acid production tank 1 and the methan production tank 2 for cleaning. The wastewater after cleaning is discharged through the slag outlet pipes 28 and the slag outlets.

[0056] The first photoelectrochemical integrated device 17 includes a first integrated plate 29 vertically installed on the inner wall of the hydrolysis acid production tank 1. The first integrated plate 29 is provided with a first photochemical mounting groove. The upper and lower sides of the first photochemical mounting groove are respectively provided with a first electrochemical upper mounting groove and a first electrochemical lower mounting groove. A first electrochemical device 30 is installed in both the first electrochemical upper mounting groove and the first electrochemical lower mounting groove. A first photochemical device 31 is installed in the first photochemical mounting groove.

[0057] The second photoelectrochemical integrated device 18 includes a second integrated plate 35 vertically installed on the inner wall of the methanogenic tank 2. The second integrated plate 35 is provided with a second photochemical mounting groove. The upper and lower sides of the second photochemical mounting groove are respectively provided with a second electrochemical upper mounting groove and a second electrochemical lower mounting groove. A second electrochemical device 36 is installed in both the second electrochemical upper mounting groove and the second electrochemical lower mounting groove. A second photochemical device 37 is installed in the second photochemical mounting groove.

[0058] The first electrochemical device 30 includes a microbial fuel cell, and the second electrochemical device 36 includes a microbial electrolysis cell. The top cover of the hydrolysis acid production tank 1 is provided with a first wire hole, and the methanation tank 2 is provided with a second wire hole. The microbial fuel cell is connected to a first wire 33, and the microbial electrolysis cell is connected to a second wire 34. The first wire 33 and the second wire 34 pass through the first wire hole and the second wire hole respectively and are connected in series. They are also connected to a voltage regulator and an external power supply 32.

[0059] Both microbial fuel cells and microbial electrolyzers are modularly designed. A single module can treat a certain amount of organic-rich wastewater. The number of modules can be adjusted according to different wastewater characteristics and treatment requirements to achieve flexible treatment capacity and facilitate later maintenance. Each module contains anode and cathode electrodes. Both electrodes of the microbial fuel cell and microbial electrolyzer are made of carbon cloth material with a thickness of 0.5-2 mm and a width of 2-5 cm. The anode and cathode of the microbial fuel cell and microbial electrolyzer are arranged in parallel. The first integrated plate 29 and the second integrated plate 35 are both made of insulating material. The anode and cathode of the microbial fuel cell and microbial electrolyzer are close to the tank wall and fixedly spaced by the first integrated plate 29 and the second integrated plate 35 to ensure a uniform electric field distribution between the electrodes, maximize the efficiency of electron transfer and light utilization, and effectively promote electrochemical reactions. The cathode and anode materials of the microbial fuel cell are coated with a hematite catalyst film (doped with 5% TiO2) to accelerate the redox reaction involving electrons, protons and acceptors in the electrolyte, generating water or other compounds, thereby increasing the reaction rate. The surfaces of the anode and cathode of the microbial fuel cell are roughened to increase the microscopic surface area, provide more active sites, increase the amount of microbial attachment, and promote the anode reaction.

[0060] like Figure 4 As shown, taking the MFC and MEC series connection as an example, the microbial fuel cell and the microbial electrolyzer are connected in series via the first wire 33 and the second wire 34. This allows the electrical energy generated by the microbial fuel cell to supply the microbial electrolyzer, supplementing the energy deficit under high electrolysis demand. Simultaneously, a voltage regulator and an external power supply 32 ensure the microbial electrolyzer receives the necessary voltage support during electrolysis, ensuring the continuous and stable operation of the system, especially when the electrolysis demand exceeds the power output of the microbial fuel cell. Furthermore, by connecting the microbial fuel cell and the microbial electrolyzer in series via the first wire 33 and the second wire 34, the organic-rich wastewater undergoes oxidation at the anode and reduction at the cathode in the hydrolysis acid-producing tank 1. Simultaneously, the liquid after hydrolysis acid production in the methanogenic tank 2 undergoes oxidation at the anode and reduction at the cathode. This completes the electrochemical connection, further accelerating the reaction rate. The first wire 33 and the second wire 34 are equipped with a voltage regulator and an external power supply 32 to maintain circuit stability. The set voltage is between 0.8 and 1.5V, and the current density is between 30 and 50 mA / m. 2Meanwhile, in the microbial electrolysis cell, the added photochemical material hematite also functions as an electrochemical material, with an addition amount of 2–5 g / L. Under the action of the stirring device, it can fully utilize light to generate photoelectrons, replenish electron energy loss, promote electron transfer in the reaction process, and improve the overall reaction efficiency. In the microbial fuel cell, pretreated zeolite is added as an electrochemical material through the auxiliary feed inlet at a dosage of 0.5–5 g / L. Zeolite has multiple electrochemical effects, which can significantly improve the electrochemical reaction rate. For example, the porous structure of zeolite can provide a large number of surface active sites, which helps microorganisms attach and grow at the anode; the adsorption performance of zeolite can remove harmful substances such as heavy metals and ammonia nitrogen from wastewater, while providing a stable microenvironment to promote the metabolic activities of microorganisms; the ion exchange capacity of zeolite can help regulate the pH value in the microbial fuel cell and maintain the chemical balance of the system; zeolite can slowly release trace elements required for microbial growth, promoting microbial growth and metabolism.

[0061] The anode of the microbial fuel cell is installed in the first electrochemical upper installation tank, the cathode of the microbial fuel cell is installed in the first electrochemical lower installation tank, the cathode of the microbial electrolysis cell is installed in the second electrochemical upper installation tank, and the anode of the microbial electrolysis cell is installed in the second electrochemical lower installation tank.

[0062] The first photochemical device 31 includes a first LED light strip with a width of 2-5 cm, and the second photochemical device 37 includes a second LED light strip with a width of 2-5 cm. Both the first and second LED light strips are insulated. The first LED light strip is a blue-green LED light, which can affect the genetic processes of microorganisms such as RNA transcription, DNA replication, and nucleotide excision and repair, increasing the abundance of acid-producing bacteria by more than 30% compared to dark fermentation, and promoting the symbiotic growth of hydrolytic bacteria, acid-producing bacteria, and hydrogen-producing bacteria. The second LED light strip is a white LED light. White light can regulate microbial behavior at the cellular and population levels, diversify functional microorganisms, induce enhanced cell activity, stimulate the growth of methanogens, increase the abundance of methanogens by 40%-80%, accelerate the consumption of volatile fatty acids during the start-up phase, and facilitate the adaptation of methanogens and the production of CH4. The first LED light strip is installed in the first photochemical mounting tank, located between the anode and cathode of the microbial fuel cell. The second LED light strip is installed in the second photochemical mounting tank, located between the cathode and anode of the microbial electrolysis cell. This design maximizes the photoresponse of the microorganisms attached to the electrodes, promoting their proliferation and metabolism. Furthermore, the intelligent monitoring device 3 can adjust the light source wavelength, light intensity, and irradiation time to meet the optimal fermentation conditions required for microbial growth and metabolism in different fermentation environments, preventing photoinhibition caused by excessive light exposure. This ensures fermentation occurs in the optimal environment and minimizes resource waste. Both the first and second LED light strips emit light of specific wavelengths.

[0063] The system performance is optimized using an intelligent monitoring device 3, which comprises five parts: sensors, a cloud storage module, a controller, actuators, and a remote visual monitoring module. First, the sensors detect and record various environmental parameters within the fermenter, such as temperature, pressure, pH, Eh, liquid level, stirring rate, gas production rate, carbon-to-nitrogen ratio, volatile fatty acid content, methane yield, and hydrogen yield. These parameters are then converted into electrical signals and sent to the cloud storage module for data collection and preprocessing. The controller uses machine learning algorithms to analyze and calculate the preprocessed data in the cloud storage module. Based on the analysis results, a predictive model is established to predict the optimal fermentation environment, optimizing the optimal parameters for different fermentation environments. The controller then sends real-time control commands to the actuators based on the parameters processed by the algorithm. The controller also supports dynamic adjustment of its decision model based on preset parameters and real-time data to cope with environmental changes during fermentation. The actuators adjust the fermentation environment, regulating valves, stirring devices, and other related devices according to the controller's adjustment commands, ensuring that the environment within the tank is maintained at the optimal conditions calculated by the controller. As the anaerobic fermentation system continues to operate, the intelligent monitoring device 3 continues to collect fermentation-related data. A portion of the dataset is then used for model training and continuous optimization to achieve better fermentation results and more accurate predictions. The remaining data is used to verify the model's accuracy and generalization ability, and the model is fine-tuned based on the verification results to obtain more accurate predictions. This allows for feedback regulation of the tank environment, achieving precise control of environmental parameters. The remote visualization monitoring module primarily provides a user interface, allowing users to remotely access the system via the internet to monitor and control the fermentation process, receive alarms, and receive system updates through intuitive charts and control panels.

[0064] Specifically, the control module includes a PLC controller for data analysis and calculation, and establishes a predictive model based on the analysis results to predict the optimal fermentation environment, thereby sending control commands to the execution module. The controller uses machine learning algorithms to analyze and calculate the preprocessed data in the cloud storage module, and establishes a predictive model based on the analysis results to predict the optimal fermentation environment, optimize the optimal parameters for different fermentation environments, and send real-time control commands to the actuators based on the parameters processed by the algorithm. After receiving the control commands, the actuators implement control measures to maintain the optimal environment inside the tank. As the anaerobic fermentation system continues to operate, the intelligent monitoring device 3 continues to collect fermentation-related data, and then uses a portion of the dataset for model training, continuously optimizing the model to obtain better fermentation results and more accurate predictions. The remaining data is used to verify the accuracy and generalization ability of the model, and the model is fine-tuned based on the verification results to obtain more accurate prediction results. By monitoring and adjusting various environmental parameters in real time, more suitable living conditions are provided for the main bacterial groups in the tank (hydrolytic bacteria and acid-producing bacteria in hydrolysis acid-producing tank 1, and methanogenic bacteria in methanogenic tank 2). Different bacterial groups become the dominant species in different tanks and carry out different main reactions, making fermentation more efficient and thus accelerating the anaerobic fermentation rate.

[0065] The execution module is used to receive control commands sent by the control module and precisely adjust the voltage of each valve and lamp strip according to the control commands. It includes a temperature regulator, a pH regulator, a stirring speed regulator, and a stirring time regulator.

[0066] The sensor module includes several types of sensors used to collect environmental data from the hydrolysis acid production tank 1 and the methanogenic tank 2, and transmit the measured data to the control module and the cloud storage module. The sensors detect fermentation environmental data, raw material data, and fermentation result-related data. The environmental data includes, but is not limited to, temperature, pressure, pH, Eh, liquid level, stirring rate, gas production rate, carbon-nitrogen ratio, volatile fatty acid content, methane yield, and hydrogen yield.

[0067] The cloud storage module is used to receive data measured by the sensor module, preprocess the data, and back up the data. The cloud storage module first preprocesses the data, that is, checks the data quality and cleans it, handles missing and outlier values, and standardizes or normalizes the data to ensure that different types of data are comparable. It also stores backups to ensure the timeliness, reliability and security of the data.

[0068] The remote visualization monitoring module includes at least one user interface, allowing users to remotely access the system via the internet and monitor and control the fermentation process through icons and control panels. The module presents environmental parameters visually in graphical form online, facilitating user understanding of the fermentation process, receiving alarms, and receiving system updates. Specifically, the temperature of hydrolysis acid-producing tank 1 is 35±1 ℃, and the pH is 5.5~6.5; the temperature of methanogenic tank 2 is 35±1 ℃, and the pH is 6.8~8.5. The stirring device consists of two blades installed in opposite directions and a control circuit. The blades are mounted on both sides of the bottom of the fermenter, driving the liquid to rotate. The control circuit can preset stirring parameters, such as a stirring speed of 100 r / min, a stirring time of 3 min, and a stirring interval of 12 min. The intelligent monitoring device 3 can also analyze and calculate data from the cloud storage module through the controller to optimize the stirring parameters and then replace the preset parameters to maximize efficiency.

[0069] Example 2

[0070] The difference between this example and Embodiment 1 is that both the first electrochemical device 30 and the second electrochemical device 36 include a microbial electrolysis cell. The top cover of the hydrolysis acid-producing tank 1 is provided with a first wire hole, and the methanogenic tank 2 is provided with a second wire hole. The microbial electrolysis cell of the hydrolysis acid-producing tank 1 is connected to a first wire 33, and the microbial electrolysis cell of the methanogenic tank 2 is connected to a second wire 34. The microbial electrolysis cells of the hydrolysis acid-producing tank 1 and the microbial electrolysis cells of the methanogenic tank 2 are connected in parallel through the first wire 33 and the second wire 34, and are simultaneously connected to an external power source.

[0071] Example 3

[0072] The fermentation method for an anaerobic fermentation system for organic-rich wastewater based on photoelectrochemical processes, as described in Example 1 or Example 2, includes the following steps:

[0073] (1) Add the organic-rich wastewater that has undergone pretreatment such as solid-liquid separation and oil-water separation into the hydrolysis acid production tank 1;

[0074] (2) Add the first photoelectrochemical material into the hydrolysis acid production tank 1 through the first feed inlet 16, start the first photoelectrochemical integrated device 17, adjust the voltage and current of the first electrochemical device 30 to the appropriate voltage and current parameters, and intelligently adjust the light intensity and irradiation time according to the needs, with blue-green light as the main light, to optimize the microbial activity to adapt to the light response characteristics of acid-producing bacteria and hydrolytic bacteria, thereby promoting the proliferation and metabolism of microorganisms and accelerating the formation of dominant bacterial groups; start the first stirring device 19 to ensure that the materials in the tank are mixed evenly, improve the effect of the photoelectrochemical device, and accelerate the reaction.

[0075] (3) The intelligent monitoring device 3 automatically monitors the gas content in the hydrolysis acid production tank 1. When the gas content meets the requirements of the second stage, the intelligent monitoring device 3 controls the first gas outlet valve 12 and the second gas outlet valve 13 to open, so that the gas in the hydrolysis acid production tank 1 enters the methanogenic tank 2. When the gas is excessive, the intelligent monitoring device 3 controls the second gas outlet valve 13 to close and the third gas outlet valve 14 to open for gas collection. At the same time, the fermentation liquid in the hydrolysis acid production tank 1 is transported to the methanogenic tank 2 by the transfer pump 11.

[0076] (4) Add the second photoelectrochemical material into the methanogenic tank 2, start the second photoelectrochemical integrated device 18, and adjust it to white light mode to adapt to the photoresponse characteristics of methanogenic bacteria; adjust the voltage and current of the second electrochemical device 36, and start the second stirring device;

[0077] (5) The generated methane is collected and stored through the third gas outlet branch pipe 7. Throughout the process, the intelligent monitoring device 3 adjusts various parameters, including but not limited to temperature, pH, light intensity, and stirring rate, based on real-time data to ensure that the system operates in the optimal state; the tank is cleaned regularly to prevent scum from forming a crust, thereby reducing the fermentation rate and the service life of the tank. Tap water enters the two tanks through the first water inlet branch pipe 22 and the second water inlet pipe 23. After a series of operations, it is discharged through the first scum outlet, the second scum outlet, the first scum outlet short pipe 28, and the second scum outlet short pipe 28.

[0078] The first photoelectrochemical material is pretreated hematite. 2-5 g / L of hematite is added through the first feed inlet 16 as the primary photochemical material. Under the action of the stirring device, suitable hydrodynamic conditions are created, enabling the fermentation broth to carry the hematite in a circulating manner within the LED light irradiation area, maximizing its photocatalytic effect, promoting electron transfer, and increasing the fermentation rate. LED light strips in both tanks are used to adjust the light intensity to between 100 and 300 μmol / m². 2 / s, illumination time is 60 min / d. The pretreatment process for hematite is as follows:

[0079] ① Crush the raw hematite ore to a diameter of 0.5–2 mm;

[0080] ② Roast the pulverized hematite sample in air at a temperature of 400–600℃ for 1–2 hours.

[0081] ③ The roasted hematite is soaked in dilute hydrochloric acid for 1 to 2 hours;

[0082] ④ The acid-washed hematite is washed multiple times with a large amount of deionized water until the pH of the wash water is close to neutral, and then dried in hot air at 60-80°C to constant weight for use.

[0083] The second photoelectrochemical material is pretreated zeolite. The pretreatment process for the zeolite is as follows:

[0084] ① Clean the natural or synthetic zeolite to remove surface impurities and dust, and then dry it to remove moisture;

[0085] ② Crush the dried zeolite to a diameter of 0.5–2 mm;

[0086] ③ Soak the crushed zeolite in dilute hydrochloric acid;

[0087] ④ Alkali treatment of zeolite is used to adjust its surface charge properties and improve its compatibility with electrolytes;

[0088] ⑤ The zeolite after chemical treatment is washed multiple times with a large amount of deionized water until the pH of the wash water is close to neutral, and then dried in hot air at 60-80°C to constant weight for use.

[0089] This invention is applicable to the treatment of organic-rich wastewater such as kitchen wastewater, agricultural and livestock wastewater. Taking kitchen wastewater as an example, the system operation steps and treatment effects are described in detail. Pretreatment of kitchen wastewater mainly includes solid-liquid separation, grease separation, and filtration. The main components of the pretreated kitchen wastewater are dissolved complex organic matter, suspended solid particles, and a small amount of grease. The dissolved complex organic matter mainly includes easily degradable sugars, fats, and proteins, with a total organic carbon (TOC) of approximately 15,000 mg / L; the suspended solid particles mainly consist of food residue and undigested solids, approximately 5,000 mg / L; and the cooking grease from the kitchen wastewater is approximately 2,000 mg / L.

[0090] First, pretreated organic-rich wastewater is injected into hydrolysis acid-producing tank 1. Then, hydrolysis acid-producing bacteria that have shown good fermentation results in hydrolysis acid-producing tank 1 are inoculated. The first photoelectrochemical device, the first stirring device 19, and the intelligent monitoring device 3 in hydrolysis acid-producing tank 1 are started. Pretreated hematite (first photoelectrochemical material) and zeolite (second photoelectrochemical material) are added. After fermentation reaches the predetermined stage, the fermentation liquid from hydrolysis acid-producing tank 1 is pumped into methanogenic tank 2. Methanogenic bacteria that have shown good fermentation results in methanogenic tank 2 are inoculated. The second photoelectrochemical device, the second stirring device, and the intelligent monitoring device 3 in methanogenic tank 2 are started. Pretreated hematite (photoelectrochemical material) and zeolite (photoelectrochemical material) are added. After fermentation, the generated methane and other gases are stored or treated through a gas path. The solid residue is discharged through the slag outlet and subjected to subsequent resource recovery treatment. The fermentation liquid is discharged through the liquid outlet and subjected to subsequent treatment. Subsequent analysis based on cloud-stored data revealed the following: During the hydrolysis and acid production stage, the main gaseous components were CO2 (30%–50%), H2 (5%–25%), NH3, and H2S (generally less than 1%); the biogas slurry contained volatile fatty acids (2000–5000 mg / L) and alcohols (100–1000 mg / L); the biogas residue mainly consisted of incompletely decomposed organic solids, generally including cellulose, lignin, ash, dead microbial remains, small amounts of undegraded proteins and fats, and used photoelectrochemical materials. During the methanogenesis stage, the main gaseous components were methane, carbon dioxide, and hydrogen; the biogas slurry mainly consisted of organic and inorganic acid salts released during biogas fermentation; the biogas residue mainly consisted of difficult-to-decompose organic residues, humic acids (formed by microbial decomposition of proteins and lignin polysaccharides), ash, dead microbial remains, and used photoelectrochemical materials. Kitchen wastewater: COD removal rate is expected to reach over 90%, due to photoelectrochemical technology improving the availability of organic matter; BOD removal rate is expected to reach over 85%, demonstrating highly efficient biodegradation capacity; suspended solids removal rate is expected to reach 95%, mainly achieved through physical sedimentation and biodegradation (a significant improvement compared to traditional equipment). It is estimated that approximately 50 m³ of methane will be produced per 1000 L of wastewater treated, with a methane purity of over 75% (a significant improvement compared to traditional equipment). Solid residue mainly contains non-degradable cellulose, ash, dead microbial remains, and used photoelectrochemical materials, suitable for use as a soil conditioner. This application not only improves resource utilization, such as the expected COD removal rate of over 90%, BOD removal rate of over 85%, and suspended solids removal rate of over 95% for kitchen wastewater, but also improves the availability of organic matter and demonstrates highly efficient biodegradation capacity. It is estimated that approximately 50 m³ of methane will be produced per 1000 L of wastewater treated. 3The methane used has a purity of over 75% (a significant improvement compared to traditional equipment), and the fermentation efficiency is also significantly improved. The fermentation time in hydrolysis acid-producing tank 1 is approximately 1-3 days, and in methanogenic tank 2 it is 5-7 days, with an overall treatment cycle of approximately 7-10 days (compared to 2-5 days for traditional hydrolysis acid-producing tank 1 and 10-25 days for methanogenic tank 2), representing a significant reduction in time. This application provides a new approach to improving anaerobic fermentation efficiency by incorporating intelligent technology. With the introduction of intelligent technology, the resource utilization of organic-rich wastewater is intelligently controlled, improving treatment efficiency and environmental friendliness. This not only allows for real-time monitoring of the system's operation, ensuring the safety of the fermentation process, but also improves resource utilization and fermentation efficiency, meeting the requirements for developing new productive forces.

[0091] This embodiment does not impose any limitation on the shape, material, structure, etc. of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. An anaerobic fermentation system for organic-rich wastewater based on photoelectrochemistry, characterized in that: The application relates to a hydrolysis acid production tank, a methane production tank and an intelligent monitoring device, a first gas outlet branch pipe is connected to the top cover of the hydrolysis acid production tank through a first gas outlet, the first gas outlet branch pipe is communicated with a gas outlet main pipe, the gas outlet main pipe is connected to the methane production tank through a second gas outlet branch pipe, the gas outlet main pipe is connected to a gas collection tank through a third gas outlet branch pipe, the second gas outlet branch pipe is communicated with the methane production tank through a second gas outlet, a first gas outlet valve is arranged on the first gas outlet branch pipe, a second gas outlet valve is arranged on the second gas outlet branch pipe, and a third gas outlet valve is arranged on the third gas outlet branch pipe; A first liquid outlet branch pipe is connected to the bottom plate of the hydrolysis acid production tank through a first liquid outlet, the first liquid outlet branch pipe is communicated with a liquid outlet main pipe, the liquid outlet main pipe is connected to the methane production tank through a first liquid inlet branch pipe, the first liquid inlet branch pipe is communicated with the methane production tank through a first liquid inlet, a delivery pump is arranged on the liquid outlet main pipe, liquid produced in the hydrolysis acid production tank flows into the first liquid outlet branch pipe through the first liquid outlet and then flows into the liquid outlet main pipe, and the delivery pump pumps the liquid in the liquid outlet main pipe into the methane production tank through the first liquid inlet branch pipe and the first liquid inlet for next fermentation; A main feeding port and a first auxiliary feeding port are arranged on the hydrolysis acid production tank, a first photoelectric chemical integrated device is arranged on the inner wall of the hydrolysis acid production tank, and a first stirring device is arranged in the hydrolysis acid production tank; a second auxiliary feeding port is arranged on the methane production tank, a second photoelectric chemical integrated device is arranged on the inner wall of the methane production tank, and a second stirring device is arranged in the methane production tank; The first photoelectric chemical integrated device comprises a first integrated plate arranged vertically on the inner wall of the hydrolysis acid production tank, a first photochemical mounting groove is arranged on the first integrated plate, first electrochemical upper mounting grooves and first electrochemical lower mounting grooves are arranged on the upper and lower sides of the first photochemical mounting groove respectively, first electrochemical devices are arranged in the first electrochemical upper mounting grooves and the first electrochemical lower mounting grooves, and first photochemical devices are arranged in the first photochemical mounting groove; The second photoelectric chemical integrated device comprises a second integrated plate arranged vertically on the inner wall of the methane production tank, a second photochemical mounting groove is arranged on the second integrated plate, second electrochemical upper mounting grooves and second electrochemical lower mounting grooves are arranged on the upper and lower sides of the second photochemical mounting groove respectively, second electrochemical devices are arranged in the second electrochemical upper mounting grooves and the second electrochemical lower mounting grooves, and second photochemical devices are arranged in the second photochemical mounting groove; The first electrochemical device comprises a microbial fuel cell, the second electrochemical device comprises a microbial electrolytic cell, a first wire hole is arranged on the top cover of the hydrolysis acid production tank, a second wire hole is arranged on the methane production tank, a first lead wire is connected to the microbial fuel cell, a second lead wire is connected to the microbial electrolytic cell, the first lead wire and the second lead wire are connected to each other in series after penetrating through the first wire hole and the second wire hole respectively, and a voltage stabilizing device and an external power supply are simultaneously connected to the first lead wire and the second lead wire. Both the anode and the cathode of the microbial fuel cell and the microbial electrolysis cell use carbon cloth material, and the anode of the microbial fuel cell and the cathode of the microbial electrolysis cell are subjected to surface roughening treatment, and the cathode of the microbial fuel cell and the anode of the microbial electrolysis cell are covered with hematite catalyst film; both the anode and the cathode of the microbial fuel cell and the microbial electrolysis cell use parallel layout, and the first integrated plate and the second integrated plate are insulating materials; The first upper electrochemical mounting groove is used for mounting the anode of the microbial fuel cell, the first lower electrochemical mounting groove is used for mounting the cathode of the microbial fuel cell, the second upper electrochemical mounting groove is used for mounting the cathode of the microbial electrolysis cell, and the second lower electrochemical mounting groove is used for mounting the anode of the microbial electrolysis cell; The first photochemical device includes a first LED lamp strip, and the second photochemical device includes a second LED lamp strip; both the first LED lamp strip and the second LED lamp strip are insulating lamp strips; the first LED lamp strip is a blue-green light LED lamp, and the second LED lamp strip is a white light LED lamp; the first LED lamp strip is installed in the first photochemical mounting groove and is located between the anode and the cathode of the microbial fuel cell, and the second LED lamp strip is installed in the second photochemical mounting groove and is located between the cathode and the anode of the microbial electrolysis cell; The first photoelectrochemical material is added into the hydrolysis acid production tank, and the first photoelectrochemical material is pretreated hematite; the second photoelectrochemical material is added into the methane production tank, and the second photoelectrochemical material is pretreated zeolite.

2. The photoelectrochemical-based anaerobic fermentation system for organic-rich wastewater of claim 1, wherein: A first water inlet branch pipe is connected to the first water inlet on the top cover of the hydrolysis acid production tank, the first water inlet branch pipe is connected to a water inlet main pipe, the water inlet main pipe is connected to the methane production tank through a second water inlet branch pipe, the water inlet main pipe is connected to a water storage pool through a third water inlet branch pipe, and a water pump is arranged in the water storage pool; A first water inlet valve is arranged on the first water inlet branch pipe, a second water inlet valve is arranged on the second water inlet branch pipe, and a third water inlet valve is arranged on the third water inlet branch pipe; The bottom of the hydrolysis acid production tank and the bottom of the methane production tank are both provided with a slag outlet, and a slag short pipe is connected to the slag outlet; the water pump pumps water in the water storage pool into the hydrolysis acid production tank and the methane production tank for cleaning, and the sewage after cleaning is discharged through the slag short pipe and the slag outlet.

3. The photoelectrochemical-based anaerobic fermentation system for organic-rich wastewater of claim 2, wherein: The intelligent monitoring device includes: A control module including a PLC controller, which is used for analyzing and calculating data and establishing a prediction model to predict the optimal fermentation environment, and then sending a control instruction to an execution module; The execution module is used for receiving the control instruction sent by the control module and accurately adjusting the valve and the lamp strip voltage according to the control instruction, which includes a temperature regulator, a pH regulator, a stirring speed regulator, and a stirring time regulator; The sensor module includes a plurality of types of sensors for collecting environmental data in the hydrolysis acid production tank and the methane production tank and transmitting the measured data to the control module and the cloud storage module; The cloud storage module is used for receiving the data measured by the sensor module, preprocessing the data, and backing up the data; The remote visual monitoring module includes at least one user interface, and the user remotely accesses the system through the Internet, monitors and controls the fermentation process through icons and control panels.

4. The fermentation method based on the photoelectrochemical organic matter-rich wastewater-fermenting anaerobic fermentation system according to claim 3, characterized by: The method includes the following steps: (1) adding the pretreated organic matter-rich wastewater into the hydrolysis acid production tank; (2) adding the first photoelectrochemical material into the hydrolysis acid production tank, starting the first photoelectrochemical integrated device, adjusting the voltage and current of the first electrochemical device, and starting the first stirring device; (3) the intelligent monitoring device automatically monitors the gas content in the hydrolysis acid production tank, when the gas content meets the requirement of the second stage, the intelligent monitoring device controls the first and second gas outlet valves to open, so that the gas in the hydrolysis acid production tank enters the methane production tank, when the gas is excessive, the intelligent monitoring device controls the second gas outlet valve to close and the third gas outlet valve to open for gas collection; (4) adding the second photoelectrochemical material into the methane production tank, starting the second photoelectrochemical integrated device, adjusting the voltage and current of the second electrochemical device, and starting the second stirring device; (5) collecting and storing the generated methane through the third gas outlet branch pipe.

5. The photoelectrochemical-based anaerobic fermentation process of organics-rich wastewater according to claim 4, characterized in that: The first photoelectrochemical material is pretreated hematite, and the pretreatment process of the hematite is as follows: ① crushing the hematite ore to a diameter of 0.5-2 mm; ② calcining the crushed hematite sample in an air atmosphere, the calcination temperature is 400-600℃, and the holding time is 1-2h; ③ soaking the calcined hematite in dilute hydrochloric acid for 1-2h; ④ washing the acid-washed hematite with a large amount of deionized water for multiple times, and drying in hot air at 60-80℃ to constant weight for use.

6. The photoelectrochemical-based anaerobic fermentation process of organics-rich wastewater according to claim 5, characterized in that: The second photoelectrochemical material is pretreated zeolite, and the pretreatment process of the zeolite is as follows: ① washing the natural or synthetic zeolite to remove surface impurities and dust, and then drying to remove water; ② crushing the dried zeolite to a diameter of 0.5-2 mm; ③ soaking the crushed zeolite in dilute hydrochloric acid; ④ alkali treatment of the zeolite to adjust its surface charge properties and improve its compatibility with electrolyte; ⑤ washing the chemically treated zeolite with a large amount of deionized water for multiple times, and drying in hot air at 60-80℃ to constant weight for use.

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