Method and system for hydrogen production by coupling of dark fermentation under high-salinity matrix and in-situ micro-electrolysis

Abstract

The application belongs to organic waste resource treatment, and particularly relates to a method and system for coupling hydrogen production by dark fermentation and in-situ micro-electrolysis under high salt matrix. + , Cl ‑ , etc.), which is directly used as an electrolyte of an in-situ electrochemical system without additional addition of a conductive medium or an external power supply. By constructing an integrated coupling system of dark fermentation and Fe / Cu micro-electrolysis, efficient harmless disposal of high-salt organic waste is realized, and hydrogen production by biological metabolism and hydrogen evolution by electrochemistry are cooperated to produce hydrogen. The cooperation utilizes a weak electric field generated by micro-electrolysis to regulate the interface micro-environment, and consumes organic acid and transfers electrons in-situ to relieve the metabolic stress of salt-tolerant hydrogen-producing bacteria caused by high salt osmotic pressure, so as to significantly improve the waste degradation rate and total hydrogen production, and has the dual values of pollution treatment and resourceization.

Description

Technical Field

[0001] This application pertains to the resource utilization of organic waste, and particularly relates to a method and system for hydrogen production by coupling dark fermentation and in-situ micro-electrolysis under a high-salt substrate. Background Technology

[0002] With the rapid development of industries such as marine aquaculture and high-salt kitchen waste, the generation of high-salt organic waste (salt content 5-30 g / L) is increasing year by year. If not properly disposed of, this type of waste will cause serious soil salinization and water pollution. Simultaneously, the high salinity of this waste can easily damage the cell membrane structure of microorganisms in traditional biological treatment processes (such as conventional dark fermentation), leading to intracellular osmotic pressure imbalance and significant inhibition of hydrogenase activity. When the salinity exceeds 15 g / L, the efficiency of hydrogen production through conventional dark fermentation decreases by more than 70%, or even completely stops. Therefore, the harmless disposal and resource utilization of high-salt organic waste has become a technological bottleneck restricting the green development of related industries.

[0003] Currently, dark fermentation for hydrogen production is a recognized mainstream technology for the resource-based hydrogen production from organic waste, offering advantages such as mild reaction conditions, a wide range of raw material sources, and no need for external precious metal catalysts. However, this technology has long been applied to freshwater systems, where the fermentation substrate has low conductivity, and the hydrogen production pathway relies entirely on microbial metabolism. The limited hydrogen production capacity of this single pathway restricts its potential for energy efficiency improvement. To address this, existing technologies attempt to introduce electrochemical auxiliary methods such as iron-carbon microelectrolysis, constructing electrochemical hydrogen production pathways through external power sources or the addition of electrolytes to improve the overall hydrogen production rate. However, such processes require dedicated electrodes and external power supplies, resulting in high equipment investment and operating energy consumption. The addition of electrolytes also increases operating costs, making them unsuitable for small to medium-sized high-salinity wastewater treatment projects. Furthermore, conventional iron-carbon packing materials are prone to severe caking and passivation failure in high-salinity environments, making it difficult to ensure the long-term stable operation of the coupled hydrogen production system. Summary of the Invention

[0004] This application aims to provide a method and system for hydrogen production by coupling dark fermentation and in-situ micro-electrolysis under a high-salt substrate, in order to solve the above-mentioned technical problems.

[0005] To address the aforementioned technical problems, this application provides a method for hydrogen production through a combination of dark fermentation and in-situ microelectrolysis under a high-salt substrate. The method includes: using a high-salt organic substrate slurry as a natural electrolyte; conducting dark fermentation with salt-tolerant hydrogen-producing bacteria; and constructing an in-situ microelectrolysis system without an external power source using Fe / Cu mesh composite metal packing material. Under anaerobic conditions, hydrogen is produced synergistically through a dual pathway of biological metabolic hydrogen production and in-situ electrochemical hydrogen evolution. The synergistic hydrogen production process includes periodic regeneration of the Fe / Cu mesh composite metal packing material.

[0006] In one embodiment, obtaining the high-salt organic matrix slurry includes: adjusting the pH of the original high-salt organic matrix slurry with a salt content of 5-30 g / L to 4.5-6.0, and removing large particulate solid impurities to obtain the high-salt organic matrix slurry.

[0007] In one embodiment, obtaining the salt-tolerant hydrogen-producing bacterial community includes: using anaerobic activated sludge as the original bacterial strain and inoculating the original bacterial strain into an organic matrix slurry; subjecting the original bacterial strain to salt tolerance through a gradient salt increase method, and then screening to obtain the salt-tolerant hydrogen-producing bacterial community.

[0008] In one embodiment, the volume ratio of the high-salt organic matrix slurry to the bacterial solution corresponding to the salt-tolerant hydrogen-producing bacteria is (65~85):(15~35), and the volatile solids concentration of the bacterial solution is 2.5~4.0 gVS / L.

[0009] In one embodiment, obtaining the Fe / Cu mesh composite metal filler includes: stacking iron mesh and copper mesh between two insulating rods, and binding and fixing the iron mesh and copper mesh with high-temperature resistant straps, so that the entire node of the iron mesh and copper mesh is tightly fitted to form Fe / Cu mesh composite metal filler.

[0010] In one embodiment, at least one of the following is satisfied: the high-salt organic matrix slurry includes a salt-resistant additive; the parameters of the anaerobic conditions include: temperature of 33~37℃, system pH of 4.5~6.0, hydrogen partial pressure of 300~800Pa, and intermittent stirring; the cycle of the periodic regeneration treatment is 7~10 days.

[0011] In one embodiment, the Fe / Cu mesh composite metal packing is subjected to periodic regeneration treatment, which includes: applying voltage through an external power source, using a titanium rod as the positive terminal and a 4-phase rotor slot as the negative terminal, to electrochemically regenerate the Fe / Cu mesh composite metal packing, thereby dissolving the passivation layer on the surface of the Fe / Cu mesh composite metal packing and causing the biofilm to detach.

[0012] This application also provides a system for hydrogen production through dark fermentation coupled with in-situ micro-electrolysis under a high-salt substrate. The system includes: a reactor having a containment cavity; a cover disposed on top of the reactor for sealing the containment cavity; and Fe / Cu mesh composite metal packing disposed within the containment cavity. The containment cavity is used to contain a high-salt organic substrate slurry and salt-tolerant hydrogen-producing bacteria. The high-salt organic substrate slurry, as a natural ion electrolyte, together with the Fe / Cu mesh composite metal packing, constitutes an in-situ micro-electrolysis system without an external power source.

[0013] In one embodiment, at least one of the following is satisfied: the cover includes an outer cover fixed to the top of the reactor and an inner cover disposed inside the reactor, the inner cover dividing the reactor into a sealed chamber located above the inner cover and a fermentation chamber located below the inner cover; the Fe / Cu mesh composite metal packing includes: two insulating rods and stacked iron mesh and copper mesh fixed between the two insulating rods, the iron mesh and copper mesh being bound and fixed by high-temperature resistant straps, and the two are tightly fitted at all nodes; the bottom of the reactor is provided with a solid-liquid separation outlet and a liquid return outlet, the liquid return outlet being connected to the upper part of the reactor for realizing vertical external circulation of the fermentation liquid.

[0014] In one embodiment, the system further includes: a motor disposed within the sealed chamber, a four-phase rotor slot disposed at the center of the inner cover, and a titanium rod penetrating the inner cover; wherein the Fe / Cu mesh composite metal packing consists of multiple sets arranged in a ring along the inner side of the reactor's containment cavity, and adjacent sets of Fe / Cu mesh composite metal packing share a single insulating rod; the upper ends of each insulating rod converge and connect to the four-phase rotor slot via a central vertical shaft; wherein the output end of the motor is connected to the four-phase rotor slot for driving the Fe / Cu mesh composite metal packing to rotate synchronously within the fermentation chamber; wherein the upper end of the titanium rod is connected to the positive terminal of an external power supply, and the lower end is connected to the Fe / Cu mesh composite metal packing; the four-phase rotor slot is connected to the negative terminal of the external power supply; an electrochemical regeneration circuit is formed between the external power supply, the titanium rod, the Fe / Cu mesh composite metal packing, and the four-phase rotor slot.

[0015] This application protects a method for hydrogen production through dark fermentation coupled with in-situ microelectrolysis under a high-salt substrate. The method includes: using a high-salt organic substrate slurry as a natural electrolyte, carrying out dark fermentation with salt-tolerant hydrogen-producing bacteria, and constructing an in-situ microelectrolysis system without an external power source using Fe / Cu mesh composite metal packing material. Under anaerobic conditions, hydrogen is produced synergistically through a dual pathway of biological metabolic hydrogen production and in-situ electrochemical hydrogen evolution. The synergistic hydrogen production process includes periodic regeneration of the Fe / Cu mesh composite metal packing material.

[0016] Compared with the prior art, this application has the following technical effects: (1) This invention utilizes the fact that the high-salt matrix itself is rich in free ions (Na+). + Cl -(e.g., Fe / Cu microelectrolysis), possessing naturally high electrical conductivity, can be directly used as the electrolyte in an in-situ electrochemical system without the need for additional conductive media or external power sources. By constructing an integrated coupled system of dark fermentation and Fe / Cu microelectrolysis, efficient and harmless treatment of high-salt organic waste is achieved, while hydrogen production is synergistically achieved through a dual pathway of biological metabolic hydrogen production and electrochemical hydrogen evolution. This synergistic effect utilizes the weak electric field generated by microelectrolysis to regulate the interfacial microenvironment, and alleviates the metabolic stress of high-salt osmotic pressure on salt-tolerant hydrogen-producing bacteria by consuming organic acids and transferring electrons in situ. This significantly improves the waste degradation rate and total hydrogen production, possessing both pollution control and resource recovery value.

[0017] (2) In the synergistic hydrogen production process of this application, by periodically regenerating the Fe / Cu mesh composite metal packing, the active sites on the metal surface that have become passivated or deposited due to long-term operation can be effectively restored, maintaining the stability of the galvanic cell potential difference and hydrogen evolution overpotential of the Fe / Cu microcouple, and avoiding the increase in internal resistance and the decrease in hydrogen evolution efficiency caused by the deposition of oxides on the metal surface or excessive adhesion of biofilm. This regeneration treatment ensures that the in-situ microelectrolysis system maintains a stable electrochemical hydrogen evolution contribution rate during long-term operation, while ensuring the trace amounts of Fe² generated by microelectrolysis. + Continuous release maintains a positive stimulating effect on the metabolic activity of hydrogen-producing functional bacteria, thereby ensuring that the synergistic effect of the dual pathways of biological and electrochemical hydrogen production does not deteriorate with prolonged operation time, significantly extending the service life of the packing material and reducing replacement costs, and ensuring the long-term stability of hydrogen production rate and waste degradation efficiency during continuous industrial operation.

[0018] (3) The Fe / Cu mesh composite metal packing used in this invention has both high specific surface area and excellent mass transfer performance, and is not prone to caking and clogging during long-term operation. Unlike traditional iron-carbon particle packings that suffer from pitting corrosion, cracking, and the generation of large amounts of iron debris and sludge, in this invention, the copper cathode is firmly bonded to the surface of the iron substrate, and the iron substrate releases Fe²⁺ through uniform, layer-by-layer dissolution. + The copper phase detaches without loss, fundamentally avoiding problems such as packing pulverization, bed channeling, dead zones, and local pH imbalance. This significantly reduces the system's suspended solids load and operation and maintenance replacement costs, ensuring the long-term stable hydrogen evolution contribution rate of the micro-electrolysis system.

[0019] (4) This invention, by setting an openable outer cover at the top of the reactor and combining it with a vertical external circulation pipeline design (i.e., the liquid return port at the bottom of the reactor is connected to the circulation loop formed at the top), allows relevant operators to easily access sampling devices, monitoring probes, or dosing / bacterial dosing devices through the vertical pipeline when they need to intervene in the hydrogen production process inside the reactor. This enables real-time monitoring, sampling, and material replenishment of the hydrogen production microenvironment inside the reactor. This design can precisely adjust and control hydrogen parameters without damaging the anaerobic environment of the reactor, effectively avoiding the frequent system collapses caused by vicious competition among bacterial communities, metabolic imbalances, or acidification inhibition in traditional biological hydrogen production systems, and significantly improving the reaction system's resistance to external disturbances and long-term operational reliability. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a system diagram of hydrogen production through the coupling of dark fermentation and in-situ micro-electrolysis under high-salt substrate. Figure 2 This is a diagram of the overall structure of the Fe / Cu mesh composite metal filler; Figure 3 This is a diagram of the composite structure of iron mesh and copper mesh in Fe / Cu mesh composite metal filler; Figure 4 This is a system elution structure diagram of hydrogen production coupled with dark fermentation and in-situ micro-electrolysis under high-salt substrate. Attached reference numerals: 1-reactor, 2-outer cover, 3-inner cover, 4-Fe / Cu mesh composite metal packing, 5-liquid reflux port, 6-iron mesh, 7-copper mesh, 8-insulating rod, 9-motor, 10-4-phase rotor slot, 11-central vertical shaft. Detailed Implementation

[0021] The present invention will be further described in detail below through specific embodiments. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0022] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification are only for clearly describing a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0023] A method for hydrogen production coupled with dark fermentation and in-situ microelectrolysis under a high-salt substrate, the method comprising: using a high-salt organic substrate slurry as a natural electrolyte, carrying out dark fermentation with salt-tolerant hydrogen-producing bacteria, and constructing an in-situ microelectrolysis system without an external power source using Fe / Cu mesh composite metal packing material, and producing hydrogen synergistically through a dual pathway of biological metabolic hydrogen production and in-situ electrochemical hydrogen evolution under anaerobic conditions; wherein, the synergistic hydrogen production process includes periodic regeneration treatment of the Fe / Cu mesh composite metal packing material.

[0024] This invention utilizes the fact that the high-salt matrix itself is rich in Na + Cl - Free ions, naturally possessing high conductivity, can be directly used as the electrolyte in in-situ galvanocoupler systems without the need for additional conductive media or external power sources. By constructing an integrated coupling system of dark fermentation and Fe / Cu micro-electrolysis, efficient and harmless treatment of high-salt organic waste is achieved, while simultaneously realizing synergistic hydrogen production through both biological metabolic processes and galvanocoupler hydrogen evolution. This synergistic system, on the one hand, leverages the high-salt medium to enhance electron conduction between Fe-Cu galvanocouplers, utilizing the interface effect of the galvanocoupler reaction to regulate the local microenvironment; on the other hand, it alleviates the metabolic stress caused by organic acid accumulation and high salt osmotic pressure on salt-tolerant hydrogen-producing bacteria by in-situ consuming organic acids in the fermentation system and directionally transferring electrons, thereby significantly improving the degradation efficiency of organic waste and the total hydrogen production, possessing the dual value of pollution control and energy resource utilization.

[0025] In the synergistic hydrogen production process of this application, the periodic regeneration treatment of the Fe / Cu mesh composite metal packing effectively restores the active sites on the metal surface that have become passivated or deposited due to long-term operation. This maintains the stability of the galvanic cell potential difference and hydrogen evolution overpotential of the Fe / Cu microelectrode, and avoids the increase in internal resistance and the decrease in hydrogen evolution efficiency caused by metal surface oxide deposition or excessive biofilm adhesion. This regeneration treatment ensures that the in-situ microelectrolysis system maintains a stable electrochemical hydrogen evolution contribution rate during long-term operation, while guaranteeing the trace amounts of Fe² produced by microelectrolysis. + Continuous release maintains a positive stimulating effect on the metabolic activity of hydrogen-producing functional bacteria, thereby ensuring that the synergistic effect of the dual pathways of biological and electrochemical hydrogen production does not deteriorate with prolonged operation time, significantly extending the service life of the packing material and reducing replacement costs, and ensuring the long-term stability of hydrogen production rate and waste degradation efficiency during continuous industrial operation.

[0026] In one embodiment, the bimetallic component in the Fe / Cu mesh composite metal packing can also be one of lanthanum-iron (La-Fe), cerium-iron (Ce-Fe), cerium-copper (Ce-Cu), gadolinium-iron (Gd-Fe), samarium-iron (Sm-Fe), or ytterbium-iron (Yb-Fe). For ease of description, the following description uses the Fe / Cu mesh composite metal packing as an example.

[0027] In one embodiment, obtaining a high-salt organic matrix slurry includes: adjusting the pH of an original high-salt organic matrix slurry with a salt content of 5-30 g / L to 4.5-6.0, and removing large particulate solid impurities to obtain the high-salt organic matrix slurry.

[0028] Controlling the salt content of high-salt organic matrix slurry to 5-30 g / L ensures that the slurry has sufficient free ions (Na+). + Cl - (etc.) to form a naturally high-conductivity electrolyte, meeting the ion conduction requirements of the in-situ micro-electrolysis system and avoiding the need for additional conductive media. Adjusting the pH to 4.5~6.0 is a result that balances the optimal growth pH (slightly acidic) for dark fermentation hydrogen-producing bacteria with the pH range for efficient electrochemical corrosion of Fe / Cu microcouples. Studies have shown that Fe / Cu microelectrolysis can maintain high electrochemical corrosion activity and Fe²⁺ under weakly acidic conditions. + Release rate. Removing large solid impurities can prevent packing blockage and local concentration polarization, ensuring sufficient contact between the slurry and the packing surface, and providing a homogeneous reaction environment for subsequent synergistic hydrogen production.

[0029] In one embodiment, obtaining the salt-tolerant hydrogen-producing bacterial community includes: using anaerobic activated sludge as the original bacterial strain, inoculating the original bacterial strain into an organic matrix slurry, acclimating the original bacterial strain to salt tolerance through a gradient salt increase method, and then screening to obtain the salt-tolerant hydrogen-producing bacterial community.

[0030] High-salt environments exert significant osmotic stress on common anaerobic hydrogen-producing bacteria, leading to cell dehydration, metabolic enzyme inactivation, and even death. This application employs a gradient salting method to acclimate raw anaerobic activated sludge to salt tolerance. By gradually increasing the salt concentration of the culture medium, gene expression regulation and population succession occur during the adaptation process, enriching a dominant hydrogen-producing bacterial community with high salt tolerance. The selected salt-tolerant hydrogen-producing bacterial community can maintain high hydrogenase activity and hydrogen production metabolic flux under salinity conditions of 5–30 g / L, solving the bottleneck problem of low biological hydrogen production efficiency in high-salt substrates and providing a stable biological metabolic basis for dual-pathway synergistic hydrogen production.

[0031] It should be noted that the organic matrix slurry used for acclimatization is the same as the natural electrolyte mentioned above, except for the salinity; moreover, the acclimatization gradient generally starts from 5 g / L, and then increases in an arithmetic progression of 3~5 g / L up to 30 g / L.

[0032] It should also be noted that the sign of successful domestication can be that the salt-tolerant hydrogen-producing bacteria that have been domesticated and stabilized at a salinity of 30 g / L are directly inoculated into the above-mentioned natural electrolyte, and then one batch is run for observation. If stable gas production is found, it is considered successful.

[0033] In one embodiment, the volume ratio of the high-salt organic matrix slurry to the bacterial liquid corresponding to the salt-tolerant hydrogen-producing bacteria is (65~85):(15~35), and the volatile solids concentration of the bacterial liquid is 2.5~4.0 gVS / L.

[0034] After the high-salt organic matrix slurry and the bacterial solution corresponding to the salt-tolerant hydrogen-producing bacteria are mixed and inoculated at a volume ratio of (65~85):(15~35), as the acclimatization or enrichment process in the reactor proceeds, the hydrogen-producing bacteria gradually adapt to the high-salt environment and proliferate, and the concentration of volatile solids and metabolic activity in the bacterial solution change accordingly. In actual operation, the initial volume ratio can be dynamically adjusted according to the stability of the reactor environment and changes in the hydrogen production rate, with the adjustment range typically ±5%. That is, when the activity of the hydrogen-producing bacteria is significantly enhanced, the proportion of bacterial solution can be appropriately reduced to adjust the volume ratio to (75~85):(15~25); when the activity of the hydrogen-producing bacteria is insufficient, the proportion of bacterial solution can be appropriately increased to adjust the volume ratio to (65~75):(25~35). This dynamic adjustment strategy helps maintain the balance between substrate and biomass in the reactor and ensures the long-term stable operation of the hydrogen production system.

[0035] In one embodiment, obtaining the Fe / Cu mesh composite metal filler includes: stacking iron mesh and copper mesh between two insulating rods, and binding and fixing the iron mesh and copper mesh with high-temperature resistant strapping to form Fe / Cu mesh composite metal filler.

[0036] This application employs a structure of stacked iron and copper meshes, physically binding them together to ensure tight adhesion at "global nodes," forming numerous pairs of micro-galvanic cells. Iron serves as the anode (Fe - 2e). - → Fe² + Copper is used as the cathode (2H) + + 2e -→ H2), spontaneously forming an electrochemical circuit in a natural high-salt electrolyte, achieving in-situ hydrogen evolution without an external power source. The network structure endows the packing with a high specific surface area and good fluid permeability, which is beneficial to the mass transfer and diffusion of substrates, ions, and hydrogen in the slurry, avoiding the problems of easy caking and clogging of traditional granular packings. High-temperature resistant binding tape and insulating rods ensure the structural stability and electrical insulation of the packing under fermentation temperature (33~37℃) and mechanical stirring conditions, preventing short-circuit interference between different Fe / Cu units.

[0037] It should be noted that each insulating rod has two independent grooves, with the iron mesh and copper mesh respectively inserted into the grooves.

[0038] In one embodiment, the high-salt organic matrix slurry includes a salt-resistant additive.

[0039] Adding salt-resistant adjuvants can further stabilize the cell membrane structure and osmotic pressure balance of the bacterial community under high salt conditions, alleviate the inhibition of metabolic activity by high salt stress, and enhance the robustness of the synergistic hydrogen production system.

[0040] Among them, the salt-resistant additives include 0.5~1.0 g / L of betaine or 4~6 g / L of wollastonite.

[0041] In one embodiment, the parameters of the anaerobic conditions include: temperature of 33~37℃, system pH of 4.5~6.0, hydrogen partial pressure of 300~800Pa, and intermittent stirring.

[0042] The optimal temperature for hydrogen production through dark fermentation is typically 33–37°C, which ensures the activity of hydrogenase in the hydrogen-producing bacteria. A pH of 4.5–6.0 balances the hydrogen production preference (weak acidity) of the dark fermentation bacteria with the efficient electrochemical corrosion conditions of the Fe / Cu microcouple.

[0043] This application utilizes the linkage control of an online hydrogen partial pressure sensor and a vacuum pump to stabilize the system's hydrogen partial pressure in real time within the range of 300–800 Pa. When the hydrogen partial pressure ≥1000 Pa, the pumping rate is automatically increased to promptly remove accumulated mixed gas within the system, avoiding feedback inhibition of the metabolic activity of hydrogen-producing bacteria (i.e., product inhibition effect) due to high hydrogen partial pressure, thus maintaining the continuous unobstructed hydrogen production metabolic pathway. When the hydrogen partial pressure is below 200 Pa, the pumping rate is reduced to prevent excessive stripping and loss of beneficial intermediate metabolites (such as volatile fatty acids) and severe disturbance of the microbial microenvironment caused by excessive pumping. This dynamic balance control strategy not only effectively eliminates the bottleneck of product hydrogen inhibition in the dark fermentation process but also provides a positive driving force for Fe / Cu micro-electrochemical hydrogen evolution by maintaining a suitable hydrogen partial pressure gradient, ensuring the long-term stable operation of the synergistic effect of the biological hydrogen production and electrochemical hydrogen evolution pathways.

[0044] The intermittent stirring parameters are set to stir once every two hours for 5 minutes each time. This intermittent stirring breaks up the accumulation of corrosion products on the packing surface and prevents the packing from becoming passivated and failing. Of course, the stirring parameters can be adjusted according to requirements.

[0045] In one embodiment, the periodic regeneration treatment of the Fe / Cu mesh composite metal packing includes: applying voltage through an external power source, using a titanium rod as the positive terminal and a 4-phase rotor slot as the negative terminal, to electrochemically regenerate the Fe / Cu mesh composite metal packing, thereby dissolving the passivation layer on the surface of the Fe / Cu mesh composite metal packing and causing the biofilm to detach.

[0046] During normal operation, the iron and copper meshes are constantly immersed in the high-salt fermentation liquid. Over time, two problems arise: first, the surface of the iron mesh will slowly rust (forming a rust layer); second, bacteria and their secretions will adhere to the mesh surface, forming a biofilm. Both of these factors reduce the electrical conductivity between the iron and copper meshes, causing a drop in the voltage of the galvanic cell and decreasing the efficiency of electrochemical hydrogen production.

[0047] During regeneration, the positive terminal of the external power supply is connected to the iron mesh via a titanium rod, and the negative terminal is connected to the four-phase rotor slot (the current is then transferred to the copper mesh). Upon energization, an electrolytic reaction occurs on the surface of the iron mesh, dissolving and peeling off the rust; the surface of the copper mesh violently bubbles, and the upward force of these bubbles directly dismantles the attached biofilm. The entire cleaning process can be completed in situ without disassembling the reactor or removing the packing material, avoiding damage to the mesh structure caused by disassembly. After cleaning, the power is de-energized, exposing the fresh metal surface of the iron mesh, and the copper mesh is also clean, allowing it to resume spontaneous hydrogen production based on the potential difference between iron and copper. Regular cleaning ensures the packing material can be used for a long time without replacement, resulting in low maintenance costs.

[0048] It should be noted that the 4-phase rotor slot can be adapted according to the amount of Fe / Cu mesh composite metal filler.

[0049] In one embodiment, the cycle of the periodic regeneration process is 7 to 10 days.

[0050] This application also provides a system for hydrogen production coupled with dark fermentation and in-situ micro-electrolysis under a high-salt substrate, such as... Figure 1 As shown, the system includes: a reactor 1 having a receiving cavity; a cover disposed on top of the reactor for sealing the receiving cavity; and Fe / Cu mesh composite metal packing disposed within the receiving cavity. The cavity is used to contain a high-salt organic matrix slurry and a salt-tolerant hydrogen-producing bacterial community. The high-salt organic matrix slurry, as a natural ionic electrolyte, together with the Fe / Cu mesh composite metal filler, forms an in-situ micro-electrolysis system without an external power source.

[0051] In one embodiment, the cover includes an outer cover 2 fixed to the top of the reactor and an inner cover 3 disposed inside the reactor, the inner cover dividing the reactor into a sealed chamber located above the inner cover and a fermentation chamber located below the inner cover.

[0052] The double-layer cover design (outer cover + inner cover) divides the reactor into a sealed chamber and a fermentation chamber. The sealed chamber can be used to house transmission components such as drive motors, preventing them from directly contacting the fermentation liquid and causing corrosion and pollution. The inner cover also serves as the top seal of the fermentation chamber, ensuring an anaerobic environment.

[0053] It should be noted that the cover is equipped with a nitrogen inlet and an exhaust port. The nitrogen inlet is used to introduce high-purity nitrogen into the reactor before the reaction starts, in order to remove dissolved oxygen from the top space of the reactor and the liquid phase, ensuring that the reactor is in an absolutely anaerobic environment and preventing oxygen from inhibiting the metabolic activity of the hydrogen-producing bacteria in the dark fermentation. The exhaust port is connected to a vacuum pump through a gas pipeline to promptly remove the hydrogen generated in the reactor, preventing excessively high partial pressure of hydrogen in the gas phase from causing feedback inhibition of the hydrogen production metabolic pathway.

[0054] In addition, a hydrogen partial pressure sensor is installed on the gas pipeline between the exhaust port and the vacuum pump to monitor the gas phase hydrogen partial pressure in the top space of the reactor in real time. A linkage control loop is formed between the hydrogen partial pressure sensor and the vacuum pump: when the hydrogen partial pressure sensor detects a hydrogen partial pressure ≥1000 Pa in the reactor, the vacuum pump is automatically increased to quickly remove excess mixed gas; when the hydrogen partial pressure ≤200 Pa, the pumping speed is reduced or pumping is stopped to maintain the hydrogen partial pressure in the reactor within the working range of 300–800 Pa. Through this linkage control, the gas phase hydrogen partial pressure in the reactor is always maintained within the optimal tolerance range for hydrogen-producing microorganisms, effectively relieving the product inhibition of hydrogenase activity caused by high hydrogen partial pressure, and avoiding fluctuations in the gas environment or damage to microbial activity caused by excessive negative pressure.

[0055] Optionally, an inlet valve is provided at the nitrogen inlet, and an exhaust valve is provided between the exhaust port and the vacuum pump, for cutting off the gas path during batch operation or maintenance, to facilitate the sealing of the reactor and the regeneration of the packing.

[0056] In one embodiment, the Fe / Cu mesh composite metal filler 4 includes: two insulating rods 8 and stacked iron mesh 6 and copper mesh 7 fixed between the two insulating rods 8. The iron mesh and copper mesh are bound and fixed together by high-temperature resistant straps, and their nodes are tightly fitted throughout. Figure 2 and Figure 3 As shown.

[0057] The iron mesh layer and copper mesh layer are bound and fixed together with high-temperature resistant straps, and their nodes are tightly fitted throughout. This structure aims to ensure that the iron-copper bimetallic layer forms a constant and uniform electrical contact interface in three-dimensional space, avoiding misalignment, separation, or increased contact resistance caused by liquid flow or mechanical disturbance, thereby ensuring low internal resistance conduction of the micro-electrolysis galvanic cell circuit. Based on this, the iron / copper mesh composite is further fixed between the two insulating rods of the double-mesh fixing rod (i.e., the Fe / Cu mesh composite metal packing), and suspended inside the reactor through a four-phase rotor slot. This fixing method ensures the spatial structural stability of the packing under stirring or circulating liquid impact, preventing deformation, collapse, or entanglement of the mesh, and also allows the packing to maintain sufficient and uniform wetting contact with the fermentation broth. Simultaneously, this fixing structure provides a reliable foundation for mechanical strength and electrical connection for subsequent rotation and in-situ electrochemical regeneration operations, ensuring that the packing does not shake, short-circuit, or have a uniform current distribution during rotation stirring and regeneration voltage application, thus comprehensively guaranteeing the long-term mechanical reliability and electrochemical stability of the co-generation hydrogen production system.

[0058] In one embodiment, the bottom of the reactor is provided with a solid-liquid separation outlet and a liquid return outlet 5. The liquid return outlet is connected to the upper part of the reactor to realize the vertical external circulation of the fermentation liquid.

[0059] The bottom solid-liquid separation outlet can separate and discharge fermentation residue and products. The liquid return outlet, combined with the vertical external circulation, allows the fermentation liquid to be drawn from the bottom and then flowed back into the reactor from the top, realizing the circulation and mixing of the slurry.

[0060] In one embodiment, the system further includes: a motor 9 disposed in the sealed chamber, a four-phase rotor slot 10 disposed at the center of the inner cover, and a titanium rod disposed through the inner cover; The Fe / Cu mesh composite metal packing consists of multiple groups arranged in a ring along the inner side of the reactor's containment chamber, with adjacent groups sharing a single insulating rod. The upper ends of each insulating rod converge and connect to the four-phase rotor slot via a central vertical shaft 11. The output end of the motor is connected to the four-phase rotor slot to drive the Fe / Cu mesh composite metal packing to rotate synchronously within the fermentation chamber. Figure 4 As shown; wherein, the upper end of the titanium rod is used to connect to the positive terminal of the external power supply, and the lower end is connected to the Fe / Cu mesh composite metal filler; the four-phase rotor slot or the insulating rod is used to connect to the negative terminal of the external power supply, so that the external power supply and the Fe / Cu mesh composite metal filler form an electrochemical regeneration circuit.

[0061] In this application, multiple groups of Fe / Cu mesh composite metal packing are arranged in a ring along the inner side of the reactor's containment cavity, with adjacent groups sharing a single insulating rod. This ring arrangement fully utilizes the limited circumferential space of the reactor, integrating more micro-electrolysis reaction sites within a unit volume, increasing the contact area between the packing and the high-salt slurry. Simultaneously, the sharing of a single insulating rod between adjacent groups ensures the relative positional stability of each packing group, reduces the number of rods, lowers structural complexity, and provides more ample space for the flow of fermentation broth and hydrogen, avoiding localized dead zones and mass transfer short circuits caused by excessive rod density.

[0062] The motor output is connected to a 4-phase rotor slot, the lower end of which is connected to a central vertical shaft. This central vertical shaft extends axially along the reactor, with the upper ends of each insulating rod radially connected to the side of the central vertical shaft. When the motor drives the 4-phase rotor slot to rotate, torque is transmitted to each insulating rod via the central vertical shaft, thereby causing all the Fe / Cu mesh composite metal packing material fixed between the insulating rods to rotate synchronously. This "central vertical shaft - radial insulating rod" frame structure ensures that all packing material remains strictly synchronized during rotation, avoiding mechanical interference or uneven current distribution caused by differences in individual rotational speeds.

[0063] Furthermore, during regeneration, the positive electrode of the external power supply is connected to the iron mesh via a titanium rod, making the iron mesh the anode of the electrolytic cell. The passivation layer (iron oxide) formed on its surface due to long-term operation dissolves under anodic oxidation, restoring the iron mesh to a fresh metal surface. The negative electrode of the external power supply is connected to the copper mesh via a four-phase rotor slot and wires, making the copper mesh the cathode of the electrolytic cell. A strong gas evolution reaction (hydrogen evolution) occurs on the cathode surface, and the large number of microbubbles generated physically impacts and peels off the biofilm attached to the copper mesh surface. Through the synergistic cleaning mechanism of the positive and negative electrodes, the active surfaces of both the iron and copper meshes are restored. After the external power supply is cut off, the Fe / Cu galvanic cell resumes its spontaneous micro-electrolysis hydrogen production state.

[0064] In summary, through the structural design of "ring-shaped shared rod arrangement + synchronous rotation + in-situ regeneration loop integration", the integrated functions of high-density packing, enhanced mass transfer, scale prevention and self-cleaning and in-situ regeneration are realized in the same reactor, providing a reliable device foundation for the long-term stable and efficient operation of the synergistic hydrogen production system.

[0065] Based on the above description, the present invention has the following beneficial effects: 1. Utilizing the high conductivity of the high-salt matrix itself as a natural electrolyte, no external conductive medium or power supply is required, significantly reducing operating energy consumption; 2. The integrated coupling of dark fermentation and Fe / Cu micro-electrolysis, with the dual pathways of biological hydrogen production and electrochemical hydrogen evolution, significantly increases the total hydrogen production; 3. The Fe / Cu mesh structure packing has a high specific surface area and good mass transfer performance, and is not prone to caking and clogging; 4. Periodic electrochemical regeneration treatment can effectively restore the activity of the packing, extend its service life, and ensure long-term operational stability; 5. It has the dual value of harmless treatment of high-salt organic waste and energy recovery.

[0066] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or thresholds should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0067] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0068] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for hydrogen production by coupling dark fermentation and in-situ micro-electrolysis under a high-salt substrate, characterized in that, The method includes: Using high-salt organic matrix slurry as a natural electrolyte, salt-tolerant hydrogen-producing bacteria are used for dark fermentation, and Fe / Cu mesh composite metal filler is used to form an in-situ micro-electrolysis system without external power supply. Under anaerobic conditions, hydrogen is produced through a dual pathway of biological metabolic hydrogen production and in-situ electrochemical hydrogen evolution. The co-generation process includes the periodic regeneration of the Fe / Cu mesh composite metal packing.

2. The method according to claim 1, characterized in that, Obtaining the high-salt organic matrix slurry includes: adjusting the pH of the original high-salt organic matrix slurry with a salt content of 5~30 g / L to 4.5~6.0, and removing large particulate solid impurities to obtain the high-salt organic matrix slurry.

3. The method according to claim 1, characterized in that, Obtaining the salt-tolerant hydrogen-producing bacterial community includes: using anaerobic activated sludge as the original bacterial strain and inoculating the original bacterial strain into an organic matrix slurry; subjecting the original bacterial strain to salt tolerance through a gradient salt increase method, and then screening to obtain the salt-tolerant hydrogen-producing bacterial community.

4. The method according to claim 3, characterized in that, The volume ratio of the high-salt organic matrix slurry to the bacterial solution corresponding to the salt-tolerant hydrogen-producing bacteria is (65~85):(15~35), and the volatile solids concentration of the bacterial solution is 2.5~4.0 gVS / L.

5. The method according to claim 1, characterized in that, Obtaining the Fe / Cu mesh composite metal filler includes: stacking iron mesh and copper mesh between two insulating rods, and binding and fixing the iron mesh and copper mesh with high-temperature resistant straps, so that the entire node of the iron mesh and copper mesh is tightly attached to form Fe / Cu mesh composite metal filler.

6. The method according to claim 1, characterized in that, Meet at least one of the following: The high-salt organic matrix slurry includes salt-resistant additives; The parameters of the anaerobic conditions include: temperature of 33~37℃, system pH of 4.5~6.0, hydrogen partial pressure of 300~800Pa, and intermittent stirring; The cycle of the regeneration process is 7 to 10 days.

7. The method according to claim 1, characterized in that, The Fe / Cu mesh composite metal filler undergoes periodic regeneration treatment, including: By applying voltage through an external power source, using a titanium rod as the positive terminal and a 4-phase rotor slot as the negative terminal, the Fe / Cu mesh composite metal packing is electrochemically regenerated, causing the passivation layer on the surface of the Fe / Cu mesh composite metal packing to dissolve and the biofilm to detach.

8. A system for hydrogen production coupled with dark fermentation and in-situ micro-electrolysis under a high-salt substrate, characterized in that, The system includes: The reactor has a containment cavity; A cover, disposed on top of the reactor, is used to seal the containment cavity; Fe / Cu mesh composite metal filler is disposed within the accommodating cavity; The cavity is used to contain a high-salt organic matrix slurry and a salt-tolerant hydrogen-producing bacterial community. The high-salt organic matrix slurry, as a natural ionic electrolyte, together with the Fe / Cu mesh composite metal filler, forms an in-situ micro-electrolysis system without an external power source.

9. The system according to claim 8, characterized in that, Meet at least one of the following: The cover includes an outer cover fixed to the top of the reactor and an inner cover disposed inside the reactor. The inner cover divides the reactor into a sealed chamber located above the inner cover and a fermentation chamber located below the inner cover. The Fe / Cu mesh composite metal filler includes: two insulating rods and stacked iron mesh and copper mesh fixed between the two insulating rods. The iron mesh and copper mesh are bound and fixed by high-temperature resistant straps, and the two are tightly fitted at all nodes. The bottom of the reactor is provided with a solid-liquid separation outlet and a liquid return outlet. The liquid return outlet is connected to the upper part of the reactor to realize the vertical external circulation of the fermentation liquid.

10. The system according to claim 9, characterized in that, The system also includes: a motor disposed in the sealed chamber, a four-phase rotor slot disposed at the center of the inner cover, and a titanium rod disposed through the inner cover; The Fe / Cu mesh composite metal packing consists of multiple sets arranged in a ring along the inner side of the reactor's containment cavity, with adjacent sets of Fe / Cu mesh composite metal packing sharing a single insulating rod; the upper ends of each insulating rod are connected to the 4-phase rotor slot via a central vertical shaft. The output end of the motor is connected to the 4-phase rotor slot, which drives the Fe / Cu mesh composite metal packing to rotate synchronously in the fermentation chamber. The upper end of the titanium rod is used to connect to the positive terminal of the external power supply, and the lower end is connected to the Fe / Cu mesh composite metal filler; the four-phase rotor slot is used to connect to the negative terminal of the external power supply; an electrochemical regeneration circuit is formed between the external power supply, the titanium rod, the Fe / Cu mesh composite metal filler, and the four-phase rotor slot.

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