A microbial electrochemical-based organic wastewater simultaneous treatment and hydrogen production device

Abstract

This invention discloses a device for simultaneous treatment and hydrogen production of organic wastewater based on microbial electrochemistry, relating to the fields of water pollution control and energy recovery technology. Specifically, it is a device for simultaneous treatment and hydrogen production of organic wastewater based on microbial electrochemistry. The device includes, in sequence, a wastewater pretreatment module, an anode biological oxidation module, an ion conduction module, a cathode catalytic reduction module, a gas collection and separation module, and an energy regulation and intelligent feedback control module. After pretreatment, the wastewater enters the anode chamber, where electrogenic bacteria oxidize organic matter, releasing protons and electrons. Electrons are transferred to the cathode via an external circuit, where a catalyst reduces water to produce hydrogen. An ion exchange membrane ensures the directional migration of protons. The system uses an intelligent module to monitor water quality and operating parameters in real time, dynamically adjusting voltage and influent load to achieve efficient and stable hydrogen production and wastewater purification.

Description

Technical Field

[0001] This invention relates to the field of water pollution control and energy recovery technology, specifically to a device for simultaneous treatment and hydrogen production of organic wastewater based on microbial electrochemistry. Background Technology

[0002] With rapid industrialization and urbanization, the discharge of industrial wastewater and domestic sewage containing large amounts of organic matter has increased dramatically, posing a serious threat to the ecological environment and human health. Traditional organic wastewater treatment methods, such as activated sludge processes and biofilm processes, while technically mature, generally suffer from drawbacks such as high energy consumption, large amounts of residual sludge, and ineffective resource recovery. The treatment of high-concentration, recalcitrant organic wastewater is particularly challenging and costly.

[0003] Meanwhile, the energy crisis is becoming increasingly severe, and the development and utilization of renewable energy has become a global consensus. Hydrogen, as a clean, efficient, and renewable secondary energy carrier, has attracted widespread attention for its production technology. Currently, large-scale industrial hydrogen production mainly relies on the reforming of fossil fuels, which not only consumes non-renewable resources but also generates large amounts of carbon dioxide emissions, failing to meet the requirements of sustainable development. Therefore, developing green and low-carbon hydrogen production technologies is of significant strategic importance.

[0004] Microbial electrochemical systems (MES), also known as microbial fuel cells (MFCs), offer a promising new approach to solving the aforementioned challenges. This system cleverly utilizes the metabolic characteristics of certain special microorganisms in nature (i.e., electrogenic bacteria). These microorganisms can directly transfer the electrons generated during the decomposition of organic matter to the anode electrode, thereby converting the chemical energy contained in wastewater into electrical energy. Subsequently, at the cathode, through an external power source or by utilizing the electricity generated by the microorganisms themselves, the electrolysis of water or other reduction reactions, such as the release of hydrogen gas, can be driven. In this way, MFC technology achieves "turning waste into treasure," purifying wastewater while simultaneously producing clean energy—hydrogen gas—truly achieving the dual goals of pollution control and energy recovery.

[0005] However, despite the promising future of MFC technology, it still faces many challenges in practical application and promotion, mainly in the following aspects: 1. Limited Energy Conversion Efficiency and Hydrogen Production Rate: The process of microorganisms oxidizing organic matter at the anode and transferring electrons to the electrode, as well as the migration of protons on the ion exchange membrane, both involve significant internal resistance and energy loss. This results in a typically low output voltage, making it difficult to directly drive an efficient hydrogen evolution reaction. To obtain a considerable amount of hydrogen production, a higher external bias voltage is often required, but this increases the system's total energy consumption and reduces net energy output. Balancing external energy input with hydrogen production gains is key to improving the system's economics.

[0006] Insufficient performance of cathode catalysts: In the cathode of MFCs, the hydrogen evolution reaction (HER) is a kinetically slow process, requiring highly efficient catalysts to reduce the reaction overpotential. Currently, platinum (Pt) and its alloys are the most effective HER catalysts, but their high cost and scarcity severely restrict the large-scale application of MFC technology. Therefore, developing inexpensive, abundant, and catalytically effective non-precious metal catalysts that approach or even surpass the performance of platinum-based materials is one of the core aspects of promoting the practical application of MFC technology.

[0007] Poor system stability: The MFC system is a complex bio-electrochemical coupling system, and its long-term stable operation is affected by a variety of factors. For example, the strictly anaerobic environment in the anode chamber is difficult to maintain, and oxygen infiltration inhibits the activity of electrogenic bacteria; fluctuations in the complex composition of wastewater affect the microbial community structure and metabolic activity; and the performance degradation of the ion exchange membrane can lead to internal short circuits in the system, reducing coulombic efficiency. In addition, the lack of effective process monitoring and feedback regulation mechanisms makes it difficult for the system to adapt to dynamic changes in water quality and quantity, resulting in unstable treatment effects and hydrogen production performance.

[0008] Weak treatment efficiency and resistance to shock loads: For actual organic wastewater with complex composition and large concentration fluctuations, untreated wastewater directly entering the MFC system will cause suspended solids and large, recalcitrant organic molecules to clog electrodes and poison microorganisms, severely affecting the system's treatment efficiency and lifespan. Therefore, how to design a reasonable pretreatment process, improve the biodegradability of wastewater, and enhance the system's adaptability to changes in water quality and quantity are problems that must be solved to realize the engineering application of MFC technology.

[0009] In summary, existing microbial electrochemical technologies still face significant technical bottlenecks in achieving efficient treatment and stable hydrogen production of organic wastewater. Developing a novel device that integrates multiple functions such as efficient pretreatment, high-performance non-precious metal catalysis, stable energy supply, intelligent process control, and enhanced internal circulation is of great significance for overcoming current technological limitations and promoting the practical application of this technology. Summary of the Invention

[0010] The purpose of this invention is to provide a device for simultaneous treatment and hydrogen production of organic wastewater based on microbial electrochemistry. By integrating anaerobic anodic oxidation and cathodic catalytic reduction processes, it achieves efficient purification of wastewater and recovery of clean energy hydrogen. Furthermore, it utilizes intelligent feedback control and external energy regulation to optimize operating parameters, reduce energy consumption, and improve the stability and economy of the system.

[0011] To achieve the above objectives, this invention provides a device for the simultaneous treatment and hydrogen production of organic wastewater based on microbial electrochemistry. This device constructs a continuous flow treatment system integrating physical, chemical, and biological reactions. Its core lies in achieving the dual goals of efficient removal of organic pollutants from wastewater and clean energy recovery through modular design. The entire system uses fluid connections to link the functional modules in series, ensuring the orderly flow of wastewater and the directional transfer of matter and energy during treatment. Specifically, the wastewater pretreatment module removes suspended solids and regulates water quality, creating suitable conditions for subsequent biological reactions; the anodic bio-oxidation module utilizes microbial metabolism to decompose organic matter and generate electrons; the ion conduction module, as the core isolation and transport component, is responsible for the directional migration of protons; the cathode catalytic reduction module receives electrons for water reduction and hydrogen production; the gas collection and separation module purifies the product hydrogen; furthermore, the energy regulation module provides the reaction driving force, while the intelligent feedback control module dynamically optimizes the overall system operation based on real-time data, thus forming a closed-loop intelligent water treatment platform.

[0012] Furthermore, the anodic bio-oxidation module maintains a strictly anaerobic environment and contains an anode electrode. The surface of the anode electrode is covered with electrogenic microorganisms capable of extracellular electron transfer, which convert the chemical energy in the organic wastewater into electrical energy and release protons. The module's design focuses on constructing a stable microbial electrochemical interface. The main body of the module typically employs a closed structure to prevent oxygen intrusion and inhibit anaerobic bacterial activity. The anode electrode is made of materials with high specific surface area and excellent conductivity, such as carbon brushes, graphite particles, or foamed metal, to provide sufficient attachment sites for the electrogenic bacteria. During operation, the anode chamber is inoculated with selected functional microorganisms. These microorganisms oxidize and decompose the organic substrates in the wastewater through metabolism. Electrons generated during this process are transferred to the anode surface via protein complexes on the cell membrane and then enter the external circuit. Simultaneously, protons generated during metabolism are released into the solution, providing necessary reactants for the subsequent cathodic hydrogen evolution reaction.

[0013] Furthermore, the cathode catalytic reduction module contains a cathode electrode, the surface of which is supported by a non-precious metal-based hydrogen evolution catalyst. This non-precious metal-based hydrogen evolution catalyst is selected from one or more transition metal sulfides, transition metal phosphides, transition metal nitrides, or composites thereof. This module aims to reduce the overpotential of the hydrogen evolution reaction (HER), thereby improving electron utilization and hydrogen yield. The cathode electrode is typically placed in a reaction environment rich in protons and electrons. To overcome the high cost of traditional platinum-based catalysts, this device employs a low-cost and highly active non-precious metal catalyst. By in-situ growing or coating the aforementioned catalyst material on the electrode substrate, the number of active sites on the electrode surface can be significantly increased, accelerating the kinetics of proton-electron combination to generate hydrogen. This achieves efficient and stable hydrogen evolution with lower energy consumption, ensuring a high level of energy conversion efficiency for the entire system.

[0014] Furthermore, the transition metal sulfide is molybdenum disulfide, cobalt sulfide, or nickel sulfide; the transition metal phosphide is cobalt phosphide or nickel phosphide. These specific catalyst materials are selected due to their unique electronic structure and surface properties. For example, the edge active sites of molybdenum disulfide have good Gibbs free energy for hydrogen adsorption, effectively promoting hydrogen generation; cobalt sulfide and nickel sulfide have high conductivity and catalytic stability. Similarly, cobalt phosphide and nickel phosphide materials not only retain the high conductivity of metals, but the introduction of phosphorus also optimizes the hydrogen adsorption energy, exhibiting catalytic performance close to that of noble metals. These catalysts are typically uniformly loaded on the cathode substrate in the form of nanoarrays or thin films, and can resist the poisoning effects of impurity ions in the water during long-term operation, maintaining highly efficient catalytic activity.

[0015] Furthermore, the energy regulation module is configured to apply a constant external bias voltage to the system, the range of which is set from 0.4 V to 1.2 V, to overcome the thermodynamic barrier of the hydrogen evolution reaction and drive electrons to migrate towards the cathode. This module, typically composed of a DC power supply or a voltage regulator circuit, is the power source for the entire microbial electrolyzer (MEC) system. The set voltage range is an optimized interval derived from thermodynamic calculations and experimental verification: too low a voltage cannot effectively drive proton reduction, while too high a voltage may lead to increased internal resistance and unnecessary energy loss. By applying this specific bias voltage, the system can break the activation energy barrier of the cathode reaction, forcing electrons to flow through the external circuit to the cathode to participate in the reduction reaction, thereby breaking the voltage limitations of traditional microbial fuel cells (MFCs) and realizing the direct conversion of chemical energy contained in wastewater into high-purity hydrogen energy under low energy consumption conditions.

[0016] Furthermore, an internal circulation loop is included, which recirculates a portion of the effluent from the cathode catalytic reduction module back to the inlet of the anode biological oxidation module to maintain the hydraulic residence time and microbial activity of the liquid within the system. This loop addresses the concentration fluctuation problem caused by intermittent influent and effluent in traditional reactors. By recirculating the effluent treated in the cathode zone to the anode front end, not only is the concentration of organic matter in the influent entering the anode chamber diluted, preventing local overload and inhibition of microbial activity, but it also acts as a stirrer, enhancing mass transfer. More importantly, cathode effluent is typically alkaline and contains residual protons; recirculation helps balance the pH value in the anode chamber, preventing a decrease in electrogenic bacteria activity due to acidification. In addition, this circulating flow mode extends the actual residence time (HRT) of the wastewater in the treatment system, ensuring sufficient time for organic matter to be thoroughly mineralized and decomposed by microorganisms, thus improving the overall pollutant removal rate.

[0017] Furthermore, the ion conduction module employs a cation exchange membrane or a proton exchange membrane. Its function is to allow protons to migrate directionally from the anode chamber to the cathode chamber, while preventing dissolved oxygen and undegraded organic matter in the wastewater from diffusing to the anode side and causing a short circuit. This module is a crucial barrier separating the anode and cathode chambers and is typically made of Nafion membranes or other polymer membrane materials. In operation, protons (H⁺) generated at the anode pass through the hydrophilic channels of the membrane under the drive of the concentration gradient to reach the cathode and participate in the reaction, thus forming a complete current loop. Simultaneously, the dense structure of the membrane material effectively prevents anaerobic bacteria in the anode chamber from contacting oxidizing substances in the cathode chamber, preventing side reactions caused by oxygen leakage that could lead to short circuits within the system. In addition, it can also trap large molecular organic matter and colloidal particles in the wastewater, preventing them from penetrating and contaminating the cathode catalyst surface, ensuring the purity and continuity of the hydrogen evolution reaction at the cathode.

[0018] Furthermore, the intelligent feedback control module incorporates a PLC controller and is connected to an online COD monitoring sensor installed on the anode outlet pipeline, a voltage / current sensor installed in the circuit, and a gas flow meter installed at the gas outlet. The PLC controller dynamically adjusts the output power of the energy regulation module and the influent load of the wastewater pretreatment module based on sensor feedback signals. This system endows the device with adaptive operation capabilities, eliminating the lag of manual operation. The COD sensor provides real-time feedback on the effluent water quality, the voltage and current sensors monitor the system's energy output status, and the gas flow meter quantifies hydrogen production. The PLC controller, acting as the central processing unit, automatically adjusts the external bias voltage to adapt to changes in influent concentration or adjusts the flow rate of the influent peristaltic pump to control load impacts through real-time acquisition and analysis of the aforementioned multi-dimensional data and a preset control algorithm. This intelligent closed-loop control strategy significantly improves the device's operational stability and resistance to shock loads.

[0019] Furthermore, the wastewater pretreatment module includes a physical filtration unit and a biological hydrolysis acidification unit. The biological hydrolysis acidification unit is used to decompose poorly soluble macromolecular organic matter into small-molecule organic acids, thereby improving the treatment efficiency of the subsequent anodic bio-oxidation module. The pretreatment module is the first line of defense to ensure the long-term stable operation of the entire system. The physical filtration unit typically uses a screen or multi-media filter to remove suspended solids and large particulate impurities from the wastewater, preventing blockage of subsequent pipelines and electrode pores. The subsequent biological hydrolysis acidification unit, under anaerobic or facultative anaerobic conditions, utilizes facultative hydrolytic fermentation bacteria to decompose complex organic matter (such as polysaccharides, proteins, and fats) in the wastewater that is difficult for electrogenic bacteria to directly utilize into small-molecule volatile fatty acids (VFAs) that are easily taken up by microorganisms. This process not only reduces the metabolic burden on the anode chamber but also converts substances that are originally difficult to degrade into high-quality electron donors, significantly improving the bioelectrochemical activity of the anode and the COD removal efficiency.

[0020] Furthermore, the gas collection and separation module includes a gas-liquid separator, a scrubbing tower, and a pressure swing adsorption (PSA) hydrogen production unit for separating the gas mixture generated at the cathode. Since the gas generated at the cathode may contain water vapor and small amounts of volatile organic compounds, it must be purified to obtain high-purity hydrogen. First, the mixed gas produced by the reaction enters the gas-liquid separator, where gravity sedimentation removes a large amount of liquid water droplets. Then, the gas is passed into the scrubbing tower, where a specific absorbent removes any trace amounts of acidic gases or ammonia. Finally, the pre-purified gas enters the pressure swing adsorption unit, where the adsorbent selectively adsorbs impurity gases (such as carbon dioxide and nitrogen) by utilizing the difference in adsorption capacity of the adsorbent for different gas components at different pressures, thus obtaining hydrogen output with purity meeting standards. This series of separation and purification steps ensures the quality and usability of the final gas product.

[0021] This invention provides a device for simultaneous treatment and hydrogen production of organic wastewater based on microbial electrochemistry, which has the following beneficial effects: 1. Achieves efficient resource utilization and energy recovery of organic wastewater: The core of this device lies in directly converting the chemical energy contained in the wastewater into electrical energy through the anodic biological oxidation module, and efficiently producing hydrogen gas through the cathode catalytic reduction module with the assistance of an external bias voltage. This design, which couples pollutant removal with clean energy production, not only solves the problem of wastewater treatment but also transforms it into high-value-added hydrogen energy products, realizing a fundamental shift from "pollution control" to "energy production," significantly reducing the operating costs of wastewater treatment, and even generating economic benefits.

[0022] This significantly improves the system's energy efficiency and economic feasibility: by loading specific non-precious metal-based hydrogen evolution catalysts (such as transition metal sulfides or phosphides) onto the cathode electrode surface, the overpotential required for the hydrogen evolution reaction is effectively reduced. Combined with the optimal external bias voltage (0.4 V to 1.2 V) applied by the energy control module, the reaction rate is maintained while minimizing additional energy consumption. This design overcomes the bottleneck of high energy consumption in traditional water electrolysis, enabling the entire system to operate stably with lower energy consumption, greatly enhancing the practical application value and commercial potential of the technology.

[0023] The stability and anti-interference capability of the microbial electrochemical process were enhanced: the device constructed a complete closed-loop control system. The biological hydrolysis acidification unit in the wastewater pretreatment module pre-decomposes large organic molecules into small acid molecules that are easily utilized by microorganisms, reducing the biological metabolic burden on the anode; the ion conduction module uses a specific functional exchange membrane to effectively block interfering factors such as dissolved oxygen from entering the anode chamber, protecting the activity of electrogenic bacteria; and the intelligent feedback control module dynamically adjusts the influent load and system power by monitoring parameters such as COD, voltage, current, and gas production in real time. These measures work synergistically to ensure the long-term stable operation of the system under complex water quality conditions.

[0024] The process flow was optimized and the effluent quality improved: By setting up an internal circulation loop, the effluent from the cathode chamber is returned to the anode inlet. This maintains an appropriate hydraulic residence time within the system, ensuring the full progress of the biochemical reactions. Furthermore, the alkaline environment of the cathode chamber helps neutralize acidic substances generated at the anode, alleviating anode acidification and maintaining the optimal pH environment for electrogenic microorganisms. In addition, the introduction of a wastewater pretreatment module reduces the pollution load on subsequent units at the source, resulting in a significant improvement in the final effluent quality, which can directly meet higher discharge standards or be reused.

[0025] The hydrogen purification process is simplified and operational safety is ensured: the gas collection and separation module integrates gas-liquid separation, washing, and pressure swing adsorption (PSA) technologies, enabling effective treatment and purification of the gas mixture generated at the cathode to obtain high-purity hydrogen. This not only improves the utilization value of the product but also avoids potential safety hazards caused by mixed gases. The modular design of the entire unit ensures clear division of labor among functional units, facilitating flexible adjustment and expansion based on actual treatment scale and wastewater characteristics, demonstrating strong adaptability and engineering promotion value. Attached Figure Description

[0026] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0027] Figure 1 This is a flowchart of the overall system of the present invention; Figure 2 This is a flowchart of the anodic bio-oxidation module of the present invention; Figure 3 This is a flowchart of the cathode catalytic reduction module of the present invention; Figure 4 This is a flowchart of the energy regulation module of the present invention; Figure 5 This is a flowchart of the intelligent feedback control module of the present invention. Detailed Implementation

[0028] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0030] How to use: Step 1: Preparations before system startup Inspection and Connection: Confirm that all modules of the device (wastewater pretreatment module, anode biological oxidation module, ion conduction module, cathode catalytic reduction module, and gas collection and separation module) are correctly installed and fluidly connected. Check that all pipeline valves are in the correct positions.

[0031] Biofilm cultivation: A sterile culture medium containing appropriate amounts of carbon source and nutrients is injected into the anodic bio-oxidation module, and an electrogenic microbial community with extracellular electron transfer capabilities is inoculated. Under strictly anaerobic conditions, an initial external bias voltage (e.g., 0.6 V) is applied through the energy regulation module, and the module is continuously operated for a period of time until a stable and dense biofilm forms on the surface of the anodic electrode.

[0032] System flushing: Use the organic wastewater to be treated to thoroughly flush the pretreatment module, anode chamber and cathode chamber, replacing the culture medium or clean water in the system.

[0033] Step 2: Wastewater Treatment and Hydrogen Production Operation Influent: Activate the wastewater pretreatment module and pump the organic wastewater to be treated into the system. The wastewater first passes through a physical filtration unit to remove large suspended solids, and then enters the biological hydrolysis and acidification unit. In this unit, poorly soluble macromolecular organic matter is decomposed into small-molecule organic acids, providing readily available substrates for subsequent anodic bio-oxidation.

[0034] Anodizing: Pretreated wastewater enters the anodic biological oxidation module. Under a strictly anaerobic environment and driven by an applied bias voltage, electrogenic microorganisms attached to the surface of the anode electrode utilize their extracellular electron transfer capabilities to oxidize organic substrates (such as small-molecule organic acids) in the wastewater, releasing protons and electrons. Electrons flow to the cathode through an external circuit.

[0035] Ion conduction: Protons generated by the anodic reaction migrate directionally to the cathode chamber through an ion conduction module (cation exchange membrane or proton exchange membrane). This membrane effectively prevents dissolved oxygen and incompletely degraded organic matter in the wastewater from diffusing to the anode side, thus preventing short circuits.

[0036] Cathodic reduction and hydrogen production: Protons migrating to the cathode chamber and electrons from the external circuit interact with the catalyst in the cathode catalytic reduction module to undergo the hydrogen evolution reaction (HER). Non-noble metal-based HER catalysts (such as molybdenum disulfide and cobalt phosphide) supported on the cathode electrode surface significantly lower the activation energy of the reaction. An external bias voltage (ranging from 0.4 V to 1.2 V) provides the necessary driving force to overcome the thermodynamic barrier of the HER, enabling electrons to migrate efficiently to the cathode and be converted into hydrogen gas.

[0037] Internal circulation: Part of the treated cathode effluent can be returned to the inlet of the anode biological oxidation module through the internal circulation loop. This operation helps maintain the hydraulic residence time of the liquid in the system within a suitable range and ensures that the anode microorganisms have high activity, thereby stabilizing the overall performance of the system.

[0038] Step 3: Product Collection and System Regulation Gas Collection and Separation: The hydrogen gas generated at the cathode, mixed with other trace gases, enters the gas collection and separation module. First, it passes through a gas-liquid separator to remove entrained liquid, then enters a scrubbing tower for further purification, and finally passes through a pressure swing adsorption (PSA) hydrogen production unit to obtain high-purity hydrogen.

[0039] Intelligent feedback control: The PLC controller collects data in real time from the COD online monitoring sensor on the anode outlet pipeline, the voltage / current sensor in the circuit, and the gas flow meter at the gas outlet.

[0040] When the COD sensor detects an increase in the COD concentration in the effluent, the PLC controller will determine that the anode treatment capacity has decreased or the influent load is too high. It will then instruct the energy control module to appropriately increase the output power (i.e., increase the external bias voltage) to enhance the electron transfer efficiency and reaction rate of the anode microorganisms.

[0041] Meanwhile, the PLC controller dynamically adjusts the influent load of the wastewater pretreatment module based on the signal from the gas flow meter to ensure a balance between hydrogen production rate and treatment effect.

[0042] If the voltage / current sensor detects abnormal fluctuations, the PLC controller will also issue an alarm and automatically adjust the operating parameters to ensure the safe and stable operation of the system.

[0043] Step 4: Shutdown and Maintenance When a shutdown is required, the inlet valve should be closed first to drain the liquid from the system. For long-term shutdowns, the electrodes should be soaked in a protective solution, and the filters and backwashing system of the pretreatment unit should be cleaned and maintained regularly.

[0044] Example: Example 1: Treatment of Organic Wastewater from the Food Industry and its Application in Hydrogen Production This embodiment demonstrates the application of this device in treating typical organic wastewater from the food industry (such as starch processing wastewater).

[0045] Wastewater Characteristics and Pretreatment The wastewater mainly contains high concentrations of macromolecular organic matter such as starch and protein, exhibiting good biodegradability but with a complex composition. The wastewater first enters the wastewater pretreatment module. In the physical filtration unit, large particulate impurities, suspended solids such as hair and fibers are removed from the wastewater through screens and mesh, preventing them from clogging subsequent pipes and contaminating the electrodes. Subsequently, the wastewater flows into the biological hydrolysis and acidification unit. In this unit, facultative anaerobic microorganisms, under anaerobic conditions, hydrolyze the insoluble macromolecular starch into oligosaccharides such as maltose and glucose, and further ferment and decompose them into small-molecule organic acids such as acetic acid, propionic acid, and butyric acid. This process not only improves the biodegradability of the wastewater but also removes some easily degradable organic matter, providing a high-quality and efficient electron donor for the subsequent anodic bio-oxidation module.

[0046] Core electrochemical treatment process The pretreated wastewater is pumped into the anodic biological oxidation module. This module maintains an absolutely anaerobic environment through strict sealing measures, preventing oxygen from entering. A dense layer of electrogenic microorganisms (such as *Geobacterium*) with extracellular electron transport capabilities has been successfully cultivated on the surface of the anode electrode within the module. Driven by a constant external bias voltage provided by the energy regulation module, these microorganisms use small-molecule organic acids in the wastewater as food, completely oxidizing them through their unique metabolic pathways to obtain the energy needed for growth. During this process, the chemical energy in the organic matter is converted into electrical energy, while a large number of protons and electrons are generated. Electrons move directionally through the external circuit, while protons migrate efficiently and directionally from the anode chamber to the cathode chamber of the cathode catalytic reduction module through the ion conduction module—a high-performance proton exchange membrane. This proton exchange membrane effectively blocks dissolved oxygen and residual organic matter in the wastewater, preventing them from diffusing to the anode side, thus avoiding the ineffective consumption of electrons and ensuring the coulombic efficiency of the system.

[0047] Cathode hydrogen production and product separation In the cathode catalytic reduction module, electrons from the external circuit, protons migrating through the ion-exchange membrane, and a non-noble metal-based hydrogen evolution catalyst (molybdenum disulfide in this example) supported on the cathode surface work together to achieve a highly efficient hydrogen evolution reaction. This catalyst significantly reduces the overpotential for water splitting to produce hydrogen, allowing for a considerable hydrogen production rate even with a relatively low external bias voltage. The produced hydrogen gas mixes with a small amount of water vapor and trace amounts of other gases to form a gas mixture.

[0048] Intelligent control and system optimization Throughout the entire operation, the intelligent feedback control module plays a crucial role. Its built-in PLC controller monitors the effluent water quality in real time via an online COD monitoring sensor connected to the anode outlet pipeline. When an upward trend in COD concentration is detected, the PLC controller analyzes the situation and instructs the energy regulation module to fine-tune its output power—that is, slightly increase the external bias voltage—to stimulate the activity of anode microorganisms and improve their efficiency in oxidizing organic matter. Simultaneously, the controller dynamically adjusts the influent load of the wastewater pretreatment module based on hydrogen production information fed back from the gas flow meter at the gas outlet, ensuring the system always operates under optimal conditions and achieving a dynamic balance between treatment effectiveness and hydrogen production efficiency.

[0049] Example 2: Treatment and Hydrogen Production Application of High-Salinity Organic Wastewater from the Pharmaceutical Industry This embodiment addresses the treatment of pharmaceutical industrial organic wastewater with complex composition, which may contain certain salts and inhibitory substances.

[0050] Enhanced preprocessing and buffering This type of wastewater typically contains complex compounds that are difficult for microorganisms to utilize directly. The wastewater first enters the wastewater pretreatment module. A powerful physical filtration unit ensures that all solid impurities are retained. The crucial step is the biological hydrolysis and acidification unit, where, by adding specific hydrolytic and acidifying bacteria under controlled pH and temperature conditions, recalcitrant organic matter in the wastewater, such as antibiotic intermediates and complex drug molecules, is "cut" into simpler fatty acids and alcohols. This not only reduces the pressure on subsequent biological oxidation but also improves the system's tolerance to toxic substances.

[0051] Anti-inhibition anodizing The pretreated wastewater enters the anodic biological oxidation module. This module also maintains a strictly anaerobic environment. The electrogenic bacteria enriched on the anode electrode inside exhibit good adaptability to specific inhibitory substances. Under the stable bias voltage field provided by the energy regulation module, these microbial communities can gradually adapt to and decompose organic pollutants in the wastewater, continuously converting chemical energy into electrical energy and releasing protons. To cope with the potential impact of salinity, a cation exchange membrane was selected as the ion conduction module. This membrane allows protons and other monovalent cations to pass through while effectively blocking divalent cations and organic macromolecules, ensuring smooth ion conduction while preventing cathode scaling and anode poisoning, thus maintaining the long-term stability of the system.

[0052] High-efficiency cathode catalysis and hydrogen production In the cathode catalytic reduction module, to address potential interference from trace heavy metal ions, this example employs a composite non-precious metal-based hydrogen evolution catalyst—a cobalt phosphide / nickel phosphide composite material. This composite material combines the advantages of both phosphides, providing more and more effective hydrogen evolution active sites. Even under complex water quality conditions, it maintains excellent catalytic activity and selectivity, ensuring the efficient conduct of the hydrogen evolution reaction.

[0053] Closed-loop internal circulation and system stability To further enhance the system's efficiency in treating high-salinity wastewater, this embodiment employs an internal circulation loop. A portion of the pre-purified effluent from the cathode catalytic reduction module is returned to the inlet of the anode biological oxidation module. This design offers several advantages: first, it dilutes the high concentration of salt and potential inhibitors in the influent, protecting the activity of the anode microorganisms; second, it maintains the hydraulic retention time of the liquid within the system, preventing a sudden drop in treatment efficiency due to water quality fluctuations; and third, any small amount of incompletely degraded organic matter that may be present in the returned water can be reused by the anode microorganisms, improving the overall organic matter removal rate.

[0054] Fully automated operation management The intelligent feedback control module is crucial in this application. The PLC controller comprehensively analyzes all data from the COD online monitoring sensor, voltage / current sensor, and gas flow meter. For example, when the voltage / current sensor shows an abnormally high system voltage, the controller determines that it may be due to decreased anode biofilm activity or increased internal resistance. It then instructs the energy regulation module to adjust the voltage and may also trigger the wastewater pretreatment module to reduce the influent flow rate, giving the system time to recover and buffer, thus achieving intelligent and adaptive operation without human intervention.

[0055] Example 3: Treatment and Hydrogen Production Application of Low-Concentration Organic Wastewater from the Dyeing and Printing Industry This embodiment is applicable to the treatment of low-concentration organic wastewater from the printing and dyeing industry that still contains a large amount of dye intermediates and auxiliaries after preliminary decolorization.

[0056] Fine pretreatment and homogenization Although dyeing and printing wastewater undergoes preliminary treatment, its quality and quantity fluctuate greatly, and it contains surfactants and complexing agents. The wastewater first enters the wastewater pretreatment module. The physical filtration unit removes shed fibers and colloids. The biological hydrolysis and acidification unit acts as a "water quality stabilizer," using microbial metabolic activities to break down the rings of aromatic compounds such as aniline and naphthalene compounds in the wastewater, converting them into straight-chain small-molecule acids that are easily utilized by electrogenic bacteria. Simultaneously, it effectively degrades surfactants and some complexing agents, creating favorable conditions for subsequent treatment.

[0057] Low energy consumption and high-efficiency power generation The wastewater entering the anode biological oxidation module has a relatively low concentration of organic matter. Therefore, under the control of the energy regulation module, the system operates within a low applied bias voltage range. This strategy ensures that the electrogenic bacteria have sufficient driving force to oxidize the substrate while minimizing the input of external electrical energy, demonstrating the advantages of this device in energy recovery. In this mild and stable environment, the electrogenic bacteria on the anode electrode continuously and efficiently convert the chemical energy of organic matter into electrical energy, and the generated protons migrate to the cathode via the ion conduction module.

[0058] Selection and application of non-precious metal catalysts Considering the potentially complex components present in dyeing and printing wastewater, this example selected transition metal nitrides as non-precious metal-based hydrogen evolution catalysts in the cathode catalytic reduction module. These catalysts possess platinum-like electronic structures and excellent resistance to poisoning, enabling them to maintain stable hydrogen evolution performance in complex chemical environments, ensuring high purity and high yield of hydrogen.

[0059] Multi-module collaboration and intelligent control The intelligent feedback control module acts as the "brain" coordinating the work of all modules. When the gas flow meter shows that hydrogen production begins to decline, the PLC controller immediately retrieves data from the online COD monitoring sensor. If the data indicates that the effluent COD is close to the emission standard, it indicates a problem with the hydrogen production efficiency itself. The controller will then instruct the energy regulation module to fine-tune the voltage to find the optimal operating point. Conversely, if the COD exceeds the standard, it will prioritize instructing the wastewater pretreatment module to adjust the influent load or replace the hydrolytic acidifying bacteria, thereby maximizing hydrogen production while ensuring compliance with emission standards. This intelligent decision-making mechanism based on multi-sensor feedback gives the system a powerful ability to cope with complex operating conditions.

[0060] Example 4: Treatment of Livestock and Poultry Farming Wastewater and Application of Hydrogen Production This embodiment demonstrates the comprehensive efficiency of the device in treating livestock and poultry breeding wastewater with high concentrations and high ammonia nitrogen.

[0061] Enhanced pretreatment to address high suspended solids Livestock and poultry farming wastewater is characterized by extremely high concentrations of organic matter and suspended solids, accompanied by a strong odor. The wastewater first impacts the wastewater pretreatment module. The physical filtration unit employs multi-stage screens and multi-media filters to efficiently intercept solids such as fecal residue and feed particles. The biological hydrolysis and acidification unit faces a significant organic load. By adding high concentrations of hydrolytic acidifying bacteria and appropriate aeration and stirring (limited to the hydrolysis and acidification stage), complex proteins and fats are rapidly decomposed into volatile fatty acids, laying a solid foundation for subsequent anaerobic digestion.

[0062] Anodic bio-oxidation and ammonia nitrogen conversion The pretreated wastewater enters the anodic biological oxidation module. The strictly anaerobic environment and high concentration of electrogenic microorganisms within this module effectively treat the large amounts of short-chain fatty acids produced during hydrolysis and acidification. Driven by the energy regulation module, the anodic reaction not only removes most of the organic matter, but the protons produced also help regulate the system pH. More importantly, the metabolic processes of the anodic microorganisms can convert some ammonia nitrogen into nitrogen gas or other forms for removal, achieving simultaneous nitrogen reduction in the wastewater.

[0063] Cathodic protection and efficient hydrogen production Because aquaculture wastewater may contain high concentrations of calcium and magnesium ions, it can easily lead to membrane fouling and cathode scaling. Therefore, this system specifically selected a fouling-resistant cation exchange membrane as the ion conduction module, and the membrane is chemically cleaned regularly. In the cathode catalytic reduction module, to cope with the interference of possible trace amounts of reducing substances such as sulfides, nickel sulfide, with excellent stability, was selected as a non-precious metal-based hydrogen evolution catalyst. This catalyst exhibits good durability and catalytic activity under complex water conditions.

[0064] Strengthening internal circulation and system resilience The internal circulation loop plays a crucial role in this application. By recirculating the cathode effluent to the anode inlet, it replenishes the water lost in the anode chamber due to evaporation and sampling. Furthermore, the alkalinity of the cathode effluent neutralizes any acidity that may be generated by the anode reaction, maintaining a relatively stable pH in the system. This provides a more suitable living environment for electrogenic bacteria and significantly enhances the system's resistance and resilience to high-load and high-impact wastewater.

[0065] Remote monitoring and intelligent management The intelligent feedback control module supports remote data transmission and monitoring. Managers can view the readings of the COD online monitoring sensor, voltage / current sensor, and gas flow meter in real time via the network. When any abnormality occurs in the system, such as a sensor data deviating from the normal range, the PLC controller will automatically execute preset protection programs, such as cutting off the water supply and adjusting the voltage, and send alarm information to the management personnel, achieving intelligent and unmanned management of the device.

[0066] Example 5: Reduction and Resource Utilization of Excess Sludge from Urban Wastewater Treatment Plants This embodiment innovatively applies the device to the treatment of residual sludge in urban wastewater treatment plants, achieving sludge reduction and energy recovery.

[0067] Sludge pretreatment and liquefaction Excess sludge mainly consists of microbial cells, extracellular polymers, and adsorbed organic matter, making direct treatment difficult. The sludge is first pumped into the wastewater pretreatment module. In the physical filtration unit, the sludge's moisture content is significantly reduced through high-pressure extrusion and centrifugal dewatering. Subsequently, the sludge enters the biological hydrolysis and acidification unit. Under specific high- or medium-temperature conditions, hydrolytic and acidifying bacteria disrupt the sludge floc structure, releasing intracellular proteins, polysaccharides, and other organic matter, which are then decomposed into soluble small-molecule organic acids. This process achieves the "liquefaction" and "acidification" of the sludge, transforming it from a solid phase into a liquid substrate suitable for use by the microbial electrochemical system.

[0068] Energy conversion of sludge organic matter The liquefied sludge supernatant is fed into the anodic bio-oxidation module. Electrogenic microorganisms enriched on the anode electrode within this module efficiently "devour" these small-molecule organic acids, using them as electron donors for oxidative metabolism. Under the bias voltage provided by the energy regulation module, this process converts the sludge organic matter, which would otherwise require energy to process, into valuable electrical energy and releases protons. This is not only a sludge reduction process but also a core step in its energy and resource recovery.

[0069] Ion conduction and cathode hydrogen production The ion conduction module ensures efficient passage of protons migrating from the anode chamber to the cathode catalytic reduction module, while preventing solid particles, colloids, and other impurities in the sludge from entering the cathode chamber, thus protecting the cathode electrode and its surface-supported non-precious metal-based hydrogen evolution catalyst (such as nickel phosphide). At the cathode, the hydrogen evolution reaction proceeds smoothly, combining electrons and protons to generate high-purity hydrogen gas.

[0070] System self-sufficiency and intelligent optimization In this application, the intelligent feedback control module enables self-optimization of system operating parameters. Due to the significant fluctuations in sludge composition and concentration, the PLC controller continuously analyzes data from the online COD monitoring sensor and voltage / current sensor. When it detects that the sludge substrate concentration is too high, causing a drop in system voltage, the controller instructs the energy regulation module to increase the output voltage to maintain the reaction rate. When hydrogen production reaches its peak, it instructs the wastewater pretreatment module to accelerate the sludge feeding and liquefaction rate, ensuring that the entire system is always in an optimal energy conversion state, ultimately achieving the goal of treating waste with waste and turning waste into treasure.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry, characterized in that it comprises: The system comprises a wastewater pretreatment module, an anodic bio-oxidation module, an ion conduction module, a cathodic catalytic reduction module, a gas collection and separation module, and an energy regulation module and an intelligent feedback control module electrically connected to the anodic bio-oxidation module and the cathodic catalytic reduction module, respectively.

2. The device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry according to claim 1, characterized in that: The anodic bio-oxidation module maintains a strict anaerobic environment, and is internally provided with an anode electrode, the surface of which is attached with an extracellular electron transfer capable electrogenic microbial flora for converting chemical energy in the organic wastewater into electrical energy and releasing protons.

3. The device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry according to claim 1, characterized in that: The cathodic catalytic reduction module is internally provided with a cathode electrode, the surface of which is loaded with a non-noble metal-based hydrogen evolution catalyst selected from one or more of transition metal sulfides, transition metal phosphides, transition metal nitrides or composite materials thereof.

4. The device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry according to claim 1, characterized in that: The transition metal sulfides are molybdenum disulfide, cobalt sulfide or nickel sulfide; the transition metal phosphides are cobalt phosphide or nickel phosphide.

5. The device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry according to claim 1, characterized in that: The energy regulation module is configured to apply a constant external bias voltage to the system, the range of the external bias voltage being set to 0.4 V to 1.2 V to overcome the thermodynamic barrier of the hydrogen evolution reaction and drive the migration of electrons to the cathode.

6. The device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry according to claim 1, characterized in that: An internal circulation loop is further included, which returns the effluent of the cathodic catalytic reduction module to the inlet of the anodic bio-oxidation module to maintain the hydraulic retention time and microbial activity of the liquid in the system.

7. The device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry according to claim 1, characterized in that: The ion conduction module uses a cation exchange membrane or a proton exchange membrane, which allows protons to migrate from the anode chamber to the cathode chamber in a directional manner, while preventing the diffusion of dissolved oxygen and undegraded organic matter in the wastewater to the anode side to cause short circuit. 8.The microbial electrochemical-based organic wastewater simultaneous treatment and hydrogen production device according to claim 1, characterized in that: The intelligent feedback control module is internally provided with a PLC controller, and is connected with a COD online monitoring sensor arranged on the anode effluent pipeline, a voltage / current sensor arranged in the circuit, and a gas flow meter arranged at the gas outlet, the PLC controller dynamically adjusting the output power of the energy regulation module and the influent load of the wastewater pretreatment module according to the sensor feedback signal.

9. The device for simultaneous treatment of organic wastewater and hydrogen production based on microbial electrochemistry according to claim 1, characterized in that: The wastewater pretreatment module comprises a physical filtration unit and a biological hydrolysis acidification unit, the biological hydrolysis acidification unit being used to decompose insoluble macromolecular organic matter into small molecular organic acid to improve the treatment efficiency of the subsequent anodic bio-oxidation module.

10. The microbial electrochemical-based device for simultaneous treatment of organic wastewater and hydrogen production according to claim 1, characterized in that: The gas collection and separation module comprises a gas-liquid separator, a scrubbing tower and a pressure swing adsorption (PSA) hydrogen production unit for separating the gas mixture generated in the cathode.

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