Electro-biological membrane for wastewater denitrification treatment and preparation method of electro-biological membrane

Abstract

The embodiment of the invention provides an electrobiofilm for wastewater denitrification treatment and a preparation method, the electrobiofilm comprises a conductive carrier and a coupling bacteria layer, the coupling bacteria layer is located on the surface of the conductive carrier, the coupling bacteria layer comprises autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria, the autotrophic denitrifying bacteria comprise hydrogen autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria. The method has the advantages that nitrogen can be efficiently removed under the condition of low carbon-nitrogen ratio, the dependence on an additional organic carbon source is reduced, the wastewater treatment cost is reduced, and the nitrogen removal efficiency is improved.

Description

Technical Field

[0001] This specification relates to the field of wastewater treatment technology, specifically to an electrobiofilm for wastewater denitrification and its preparation method. Background Technology

[0002] The total nitrogen (TN) concentration in stripping wastewater is extremely high, typically ranging from 700 mg / L to 1500 mg / L. This phenomenon is mainly due to the widespread use of nitric acid in the circuit board stripping process: nitric acid, as a solvent for metal plating, directly leads to the generation of nitrate nitrogen (NO3) in the wastewater. - The content of nitrogen (N-N) increased significantly. In addition, some processes use ammonium salts (such as ammonium chloride) or organic amine complexing agents (such as ethylenediamine), which can generate ammonia nitrogen through hydrolysis, further exacerbating the total nitrogen load.

[0003] It is worth noting that stripping wastewater also commonly suffers from an imbalanced carbon-to-nitrogen ratio (C / N), indicating a severe lack of organic carbon sources. Traditional denitrification processes require a C / N ratio ≥ 3 to achieve efficient nitrogen removal, necessitating the addition of organic carbon sources such as sodium acetate and methanol, which directly leads to a significant increase in treatment and operating costs. Summary of the Invention

[0004] The purpose of this application is to provide an electrobiofilm for wastewater denitrification treatment and a preparation method thereof, which has the advantages of being able to efficiently denitrify under low carbon-to-nitrogen ratio conditions, reducing dependence on additional organic carbon sources, thereby reducing wastewater treatment costs and improving denitrification efficiency.

[0005] In a first aspect, this application provides an electrobiofilm for wastewater denitrification treatment. The electrobiofilm includes a conductive carrier and a coupled bacterial layer. The coupled bacterial layer is located on the surface of the conductive carrier and includes autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria. The autotrophic denitrifying bacteria include hydrogen autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

[0006] In some embodiments of this application, the denitrification rate of hydrogen autotrophic denitrifying bacteria is in the range of 30% to 60%; and / or, the denitrification rate of sulfur autotrophic denitrifying bacteria is in the range of 20% to 40%.

[0007] In some embodiments of this application, hydrogen autotrophic denitrifying bacteria include one or more of Paracoccus denitrifying, Alcaligenes aegilops, and hydrogen phages; and / or, sulfur autotrophic denitrifying bacteria include one or more of Thiobacillus, Thiospirillum, and Dethiobacillus; and / or, heterotrophic denitrifying bacteria include one or more of Pseudomonas, Dethiovibrio, and Bacillus.

[0008] In some embodiments of this application, the conductive carrier includes one or more of conductive carbon fiber and glass fiber.

[0009] In some embodiments of this application, the volumetric surface area of ​​the conductive carrier is 500 m². 2 / m 3 ~1000m 2 / m 3 .

[0010] In some embodiments of this application, the electrobiofilm further includes a coating located between the conductive carrier and the coupled bacterial layer. The coating comprises alginate and salt-tolerant denitrifying bacteria, wherein the inoculum amount of the salt-tolerant denitrifying bacteria is 15 g / m³. 3 ~25g / m 3 .

[0011] Secondly, this application also provides a method for preparing an electrobiofilm for wastewater denitrification treatment, the method comprising:

[0012] Inoculation process: The conductive carrier is placed in the biological tank, and anaerobic sludge and carbon source are added to the biological tank. The anaerobic sludge includes hydrogen autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria.

[0013] Activation process: Connect the conductive carrier to a DC power supply to initiate the hydrogen evolution reaction at the cathode;

[0014] Domestication process: Sulfur autotrophic denitrifying bacteria, sulfur source and pH adjuster are added to the biochemical tank, and the current is increased to 200A~250A to form a coupled bacterial layer on the surface of the conductive carrier to obtain an electrobiofilm.

[0015] In some embodiments of this application, during the inoculation process, the amount of anaerobic sludge added is 15% to 25% based on the volume of the biological treatment tank; and / or, the carbon source includes sodium acetate; and / or, the sulfur source includes sodium thiosulfate, and the amount of sulfur source added is 2160 g to 4320 g / d; and / or, the pH adjuster includes sodium bicarbonate, and the amount of pH adjuster added is equal to the amount of sulfur source added, so that the pH in the biological treatment tank is 7.0 to 8.0.

[0016] In some embodiments of this application, the preparation method further includes:

[0017] Pretreatment process: The conductive carrier is immersed in an alginate solution to form a coating on the surface of the conductive carrier.

[0018] In some embodiments of this application, during the activation process, anaerobic sludge is returned to the biological treatment tank through pipelines, and the return ratio of anaerobic sludge is 200%~400%, with the return velocity of anaerobic sludge being greater than or equal to 0.35m / s.

[0019] As can be seen from the above, the electrobiofilm and its preparation method for wastewater denitrification provided in this application include a conductive carrier and a coupled bacterial layer. The coupled bacterial layer is located on the surface of the conductive carrier and includes autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria. Among them, the autotrophic denitrifying bacteria include hydrogen autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria. By combining autotrophic denitrifying bacteria to provide electron donors through electrochemical processes, efficient denitrification is achieved without relying on a high carbon-to-nitrogen ratio. It has the advantages of being able to efficiently denitrify under low carbon-to-nitrogen ratio conditions, reducing dependence on additional organic carbon sources, thereby reducing wastewater treatment costs and improving denitrification efficiency. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit this specification. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0021] Figure 1 This is a schematic flowchart illustrating a method for preparing an electrobiofilm for wastewater denitrification treatment, as provided in some embodiments of this specification. Detailed Implementation

[0022] The embodiments of the technical solutions in this specification will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solutions in this specification and should not be construed as limiting the scope of protection of this specification.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this specification pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this specification; the terms “comprising” and “having”, and any variations thereof, in the description, claims, and foregoing drawings, are intended to cover non-exclusive inclusion.

[0024] In the description of the embodiments in this specification, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments in this specification, "multiple" means two or more, unless otherwise explicitly defined.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this specification. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] In the description of the embodiments in this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0027] In the description of the embodiments in this specification, the term "multiple" refers to two or more (including two).

[0028] Traditional denitrification processes require the addition of large amounts of organic carbon sources to maintain denitrification efficiency when dealing with high concentrations of total nitrogen and carbon-nitrogen imbalance in the treatment of stripping wastewater. This results in a significant increase in treatment and operating costs, and the treatment effect is affected by fluctuations in the supply of carbon sources.

[0029] To address this issue, this application proposes an electrobiofilm for wastewater denitrification. The electrobiofilm comprises a conductive carrier and a coupled bacterial layer located on the surface of the conductive carrier. The coupled bacterial layer includes autotrophic and heterotrophic denitrifying bacteria, specifically hydrogen-autotrophic and sulfur-autotrophic denitrifying bacteria. This electrobiofilm achieves highly efficient denitrification by constructing a unique microbial community and utilizing electrons provided by the conductive carrier, effectively solving the problems of high carbon source input and high operating costs in traditional processes.

[0030] For ease of understanding, the following explains some key terms in this embodiment:

[0031] An electrobiofilm is a biofilm formed on the surface of a conductive material and possessing electrochemical activity. Microorganisms within this biofilm can utilize electrons provided by electrodes or electrochemical reaction products as electron donors to perform material transformations, such as denitrification.

[0032] Conductive carriers form the framework of electrobiofilms, providing attachment surfaces for microorganisms and serving as a medium for electron transfer. These materials typically possess good electrical conductivity, enabling them to provide electrons under an applied electric field.

[0033] A coupled microbial layer is a biofilm formed by the synergistic action of multiple microorganisms attached to the surface of a conductive carrier. Different species in this layer work together to degrade pollutants in wastewater through the exchange of matter and energy.

[0034] Autotrophic denitrifying bacteria are microorganisms that can utilize inorganic matter as a carbon source and carry out denitrification reactions using inorganic electron donors (such as hydrogen and sulfides). They have important denitrification capabilities in environments lacking organic carbon sources.

[0035] Heterotrophic denitrifying bacteria are microorganisms that require organic matter as a carbon source and electron donor to carry out denitrification reactions. They can efficiently remove nitrogen in environments with abundant organic matter.

[0036] Hydrogen-autotrophic denitrifying bacteria are autotrophic microorganisms that can utilize hydrogen as an electron donor and inorganic carbon sources such as carbon dioxide to carry out denitrification reactions. In electrochemical systems, the hydrogen produced by the cathode hydrogen evolution reaction can be utilized by them.

[0037] Sulfate-autotrophic denitrifying bacteria are autotrophic microorganisms that can use sulfides (such as thiosulfate and hydrogen sulfide) as electron donors and inorganic carbon sources such as carbon dioxide to carry out denitrification reactions. They have the potential to remove nitrogen from wastewater containing sulfides.

[0038] This application proposes an electrobiofilm for wastewater denitrification, the core of which lies in constructing a highly efficient microbial-electrochemical coupling system. This electrobiofilm is designed to treat wastewater containing nitrogen pollutants, converting nitrate or nitrite nitrogen into nitrogen gas through denitrification by microorganisms, thereby achieving denitrification. For example, this electrobiofilm can be applied in bioreactors within industrial wastewater treatment facilities to remove total nitrogen from wastewater.

[0039] This electrobiofilm includes a conductive carrier. The conductive carrier provides a surface for microbial attachment and growth, and acts as a medium for electron transfer. The conductive carrier can be made of one or more conductive materials, such as conductive carbon fibers, fiberglass mesh, graphite felt, carbon cloth, or conductive plastics. These materials support microbial growth and allow electrons to be transported within them.

[0040] A coupled bacterial layer is formed on the surface of the conductive carrier. This coupled bacterial layer is the main active region for achieving denitrification and is composed of various microorganisms. The bacterial layer is firmly fixed to the conductive carrier through bioattachment, forming a stable biofilm structure.

[0041] This coupled biofilm comprises both autotrophic and heterotrophic denitrifying bacteria. Autotrophic denitrifying bacteria can denitrify in environments lacking organic carbon sources, utilizing inorganic electron donors; for example, they can utilize electrons provided by electrodes or inorganic reducing substances present in the environment. Heterotrophic denitrifying bacteria, on the other hand, utilize organic matter in wastewater as both a carbon source and electron donor for denitrification. The synergistic effect of these two bacterial groups allows the electrobiofilm to adapt to the nitrogen removal requirements of wastewater under different carbon source conditions.

[0042] Furthermore, this autotrophic denitrifying bacteria includes hydrogen autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria. Hydrogen autotrophic denitrifying bacteria can utilize hydrogen as an electron donor to reduce nitrate to nitrogen. Hydrogen can be generated on the cathode surface through water electrolysis. Sulfur autotrophic denitrifying bacteria, on the other hand, can utilize sulfides as electron donors to carry out denitrification reactions. For example, sulfides may be present in some industrial wastewater, and sulfur autotrophic denitrifying bacteria can effectively utilize these sulfides for denitrification. By combining these two types of autotrophic bacteria, the electrobiofilm can more flexibly utilize different inorganic electron donors, improving denitrification efficiency and environmental adaptability.

[0043] The electrobiofilm proposed in this application, by constructing a coupled bacterial layer containing hydrogen autotrophic denitrifying bacteria, sulfur autotrophic denitrifying bacteria, and heterotrophic denitrifying bacteria on the surface of a conductive carrier, can effectively utilize electrons generated by the electrodes or sulfur sources present in the environment as electron donors, significantly reducing the dependence on external organic carbon sources in traditional stripping wastewater treatment. Therefore, this electrobiofilm can reduce operating costs and improve denitrification efficiency when treating stripping wastewater with high total nitrogen concentrations and an imbalanced carbon-nitrogen ratio, providing an economical and efficient solution for wastewater treatment.

[0044] In some embodiments, the denitrification rate of the hydrogen autotrophic denitrifying bacteria is in the range of 30% to 60%; and / or, the denitrification rate of the sulfur autotrophic denitrifying bacteria is in the range of 20% to 40%.

[0045] Specifically, hydrogen autotrophic denitrifying bacteria utilize hydrogen as an electron donor to reduce nitrate to nitrogen, thus achieving nitrogen removal. The nitrogen removal rate refers to the percentage of nitrogen removed per unit time relative to the total nitrogen under specific conditions. Limiting the nitrogen removal rate of hydrogen autotrophic denitrifying bacteria to the range of 30%–60% aims to ensure that the activity and contribution of this bacterial community in the electrobiofilm reach the expected level, avoiding insufficient nitrogen removal efficiency due to excessively low activity, or potential competition or resource imbalance with other bacterial communities due to excessively high activity. The nitrogen removal rate of hydrogen autotrophic denitrifying bacteria can be controlled by optimizing environmental parameters such as electrode potential, hydrogen supply, pH, temperature, and nutrient ratio. For example, by real-time monitoring of effluent nitrate concentration and hydrogen consumption, combined with microbial activity detection, operating conditions can be dynamically adjusted to maintain the nitrogen removal rate within the specified range.

[0046] Simultaneously, sulfur-autotrophic denitrifying bacteria utilize sulfides (such as thiosulfate) as electron donors to reduce nitrates to nitrogen gas, thus achieving denitrification. The denitrification rate also refers to the percentage of nitrogen removed per unit time relative to the total nitrogen under specific conditions. Limiting the denitrification rate of sulfur-autotrophic denitrifying bacteria to the range of 20%–40% aims to ensure the activity and contribution of this bacterial community in the electrobiofilm, especially in scenarios with abundant sulfur sources or requiring co-treatment of sulfide pollution, allowing them to exert their due denitrification function and complement hydrogen-autotrophic denitrifying bacteria. The denitrification rate of sulfur-autotrophic denitrifying bacteria can be regulated by controlling factors such as the dosage of sulfur source, redox potential, pH, and temperature. For example, by precisely controlling the dosage rate of sulfur sources such as sodium thiosulfate, combined with monitoring the concentrations of nitrates and sulfates in the effluent, and assessing the abundance and activity of sulfur-autotrophic denitrifying bacteria in the biofilm, the denitrification rate can be stabilized within the range of 20%–40%.

[0047] By precisely defining the nitrogen removal rates of hydrogen autotrophic and sulfur autotrophic denitrifying bacteria in the electrobiofilm, the activity and contribution of these two key bacterial communities can be effectively controlled. This ensures that the various bacterial communities can work synergistically and efficiently during wastewater denitrification, avoiding overall performance fluctuations or resource waste caused by excessively high or low nitrogen removal efficiency of a single bacterial community. Therefore, the electrobiofilm of this application can achieve more stable and efficient nitrogen removal, improving the reliability and adaptability of wastewater treatment, and thus better meeting the effluent standards under different wastewater treatment scenarios.

[0048] In the embodiments of this application, different types of denitrifying bacteria have different denitrification efficiency and environmental adaptability. If a suitable bacterial species is not selected, the denitrification effect may be unstable or inefficient.

[0049] In some embodiments, the hydrogen autotrophic denitrifying bacteria include one or more of *Paracococcus denitrifyingus*, *Alcaligenes*, and hydrogen phages; and / or, the sulfur autotrophic denitrifying bacteria include one or more of *Thiobacillus*, *Thiospirillum*, and *Dethiobacillus*; and / or, the heterotrophic denitrifying bacteria include one or more of *Pseudomonas*, *Dethiovibrio*, and *Bacillus*.

[0050] Specifically, regarding hydrogen autotrophic denitrifying bacteria, *Paracococcus denitrifyingus*, a facultative anaerobe, can efficiently utilize hydrogen as an electron donor for denitrification and has good reducing capacity for nitrates and nitrites, thus helping to improve the nitrogen removal efficiency of the electrobiofilm. Some species of *Alcaligenes* possess hydrogen autotrophic denitrification capabilities and exhibit strong adaptability to pH changes, which is beneficial for maintaining the stable operation of the electrobiofilm under different wastewater conditions. Hydrogen phages can effectively utilize hydrogen generated from hydrogen evolution at the cathode for denitrification, thereby enhancing the hydrogen autotrophic nitrogen removal performance of the electrobiofilm.

[0051] Regarding sulfur-autotrophic denitrifying bacteria, *Thiobacillus* is a typical example, capable of using sulfides as electron donors to reduce nitrates to nitrogen gas, thus achieving synergistic removal of both sulfides and nitrates. *Thiospirillum* maintains stable denitrification activity even under fluctuating or high sulfide concentrations, contributing to improved electrobiofilm treatment capabilities for complex wastewater. Certain species of *Desulfobacterium* also exhibit sulfur-autotrophic denitrification under specific conditions, utilizing sulfur compounds for denitrification and providing a wider range of metabolic pathways for electrobiofilms.

[0052] Regarding heterotrophic denitrifying bacteria, *Pseudomonas* is a widely distributed heterotrophic bacterium with strong denitrification capabilities. It can utilize various organic carbon sources for denitrification, exhibits broad adaptability, and is an important species in wastewater denitrification treatment. *Desulfuric Vibrio* species, in the presence of organic carbon sources, can perform heterotrophic denitrification in some cases, contributing to denitrification in complex wastewater environments. Many *Bacillus* species possess denitrification capabilities and can form spores, exhibiting strong resistance to environmental stresses, thereby improving the stability and shock load resistance of electrobiofilms.

[0053] The above technical solution specifically selects certain bacterial species with high nitrogen removal efficiency and good environmental adaptability, including hydrogen autotrophic denitrifying bacteria such as *Paracococcus denitrifyingus*, *Alcaligenes*, and *Hydrophage*; sulfur autotrophic denitrifying bacteria such as *Thiobacillus*, *Thiospirillum*, and *Dethiobacillus*; and heterotrophic denitrifying bacteria such as *Pseudomonas*, *Dethiovibrio*, and *Bacillus*. The synergistic effect of these bacterial species enables the electrobiofilm to more effectively utilize hydrogen, sulfides, and organic carbon sources as electron donors, achieving stable and efficient removal of nitrates and nitrites. This optimized combination of bacterial species significantly improves the overall nitrogen removal efficiency and operational stability of the electrobiofilm, allowing it to better adapt to different wastewater qualities and operating conditions, thus overcoming the problem of poor or unstable nitrogen removal effects that may result from using only a broad range of bacterial species.

[0054] In electrobiofilms used for wastewater denitrification, the conductive carrier is the core component for realizing the function of the electrobiofilm. However, in practical applications, selecting a suitable conductive carrier material to ensure good conductivity, mechanical strength, biocompatibility, and cost-effectiveness, while effectively promoting microbial attachment and electron transfer, is a key challenge for optimizing the performance of electrobiofilms. Inappropriate selection of the conductive carrier material may lead to low denitrification efficiency or insufficient stability of the electrobiofilm.

[0055] In some embodiments, the conductive carrier includes one or more of conductive carbon fibers and glass fibers.

[0056] Specifically, conductive carbon fiber is a carbon material fiber with excellent electrical conductivity, typically prepared through carbonization and graphitization. Its high conductivity facilitates electron transfer between the carrier surface and microorganisms in the coupled bacterial layer, thereby promoting electrochemical reactions. Simultaneously, conductive carbon fiber also possesses a high specific surface area, good mechanical strength, and chemical stability, providing ample attachment sites and a stable growth environment for microorganisms, thus promoting the formation of highly active biofilms.

[0057] Glass fiber, or glass fiber, is an inorganic non-metallic material with excellent mechanical strength, corrosion resistance, and dimensional stability. Although it is not typically conductive, it serves as a component of the conductive carrier in this application, providing robust skeletal support and structural stability. For example, glass fiber can be combined with conductive carbon fiber or other conductive materials to form a composite conductive carrier that combines good conductivity and mechanical strength. The introduction of glass fiber effectively enhances the tensile and bending resistance of the conductive carrier, improving its durability and service life in complex water treatment environments. Simultaneously, it provides a stable substrate for conductive materials, ensuring the long-term stable operation of the electrobiofilm.

[0058] By applying conductive carbon fibers and / or glass fibers to conductive carriers, the overall performance of electrobiofilms can be significantly improved. Conductive carbon fibers, with their excellent conductivity, effectively promote electron transfer between the conductive carrier surface and the autotrophic and heterotrophic denitrifying bacteria in the coupled bacterial layer, thereby accelerating the denitrification reaction. Their high specific surface area provides abundant attachment sites for microorganisms, which is conducive to the formation of a stable and highly active biofilm. Meanwhile, glass fiber, as a structural material, endows the conductive carrier with excellent mechanical strength and corrosion resistance, ensuring the structural integrity and stability of the electrobiofilm during long-term operation. This material selection not only optimizes electron transfer efficiency and microbial attachment conditions but also improves the durability and applicability of the carrier, effectively overcoming the limitations of traditional conductive carrier materials in terms of conductivity, mechanical strength, and biocompatibility, thus improving the denitrification efficiency and operational stability of the electrobiofilm.

[0059] In the embodiments of this application, the physical structure of the conductive carrier is not sufficiently optimized, which may result in insufficient microbial attachment and limited mass transfer efficiency, thereby affecting the overall denitrification performance of the electrobiofilm.

[0060] In some embodiments, the volumetric surface area of ​​the conductive carrier is 500 m². 2 / m 3 ~1000m 2 / m 3 .

[0061] Volumetric surface area refers to the effective surface area per unit volume of a conductive carrier. It directly reflects the size of the space available for microbial attachment and growth, as well as the interfacial area for material exchange with wastewater. The volumetric surface area of ​​the conductive carrier is limited to 500 m². 2 / m 3 ~1000m 2 / m 3 Within a certain range, the aim is to provide an optimized structure that ensures sufficient microbial attachment while maintaining good mass transfer efficiency. To achieve this volumetric surface area, conductive carriers can employ various structural forms. For example, they can be designed as porous materials with abundant pore structures, such as porous carbon felt, porous ceramics, or conductively modified porous polymers. The micropores, mesopores, and macropores within these materials can significantly increase the internal surface area of ​​the carrier. Furthermore, conductive carriers can also be composed of fine fibrous or granular materials, such as weaving conductive carbon fibers into a felt or mesh structure with high porosity, or sintering conductive particles (such as graphene or carbon nanotube composites) into porous blocks. By controlling the fiber diameter, weaving density, particle size, or sintering conditions, the volumetric surface area can be precisely controlled. The surface roughness of the conductive carrier can also be increased through physical or chemical treatments, such as micro-etching or nanomaterial coating, thereby improving the surface area at the microscopic level. For example, for conductive carbon fibers or glass fibers, special surface treatment processes can be used to form more micro-folds or attach nano-scale conductive particles to their surfaces in order to achieve the required volumetric surface area range.

[0062] Through the above technical solution, the volumetric surface area of ​​the conductive carrier is optimized to 500 m². 2 / m 3 ~1000m 2 / m 3This significantly increases the effective surface area of ​​the conductive carrier for the attachment of coupled bacterial layers. This provides a wider growth and reproduction space for autotrophic denitrifying bacteria (including hydrogen autotrophic and sulfur autotrophic denitrifying bacteria) and heterotrophic denitrifying bacteria, promoting rapid biofilm formation, stable growth, and high-density attachment. Simultaneously, the optimized volumetric surface area greatly improves the mass transfer efficiency between microorganisms and nitrogen pollutants (such as nitrates and nitrites) and electron donors (such as hydrogen generated by cathode hydrogen evolution and sulfur sources), ensuring that reactants can efficiently reach the active sites of microorganisms and that products can leave promptly. Therefore, this technical solution effectively solves the problems of low microbial attachment, limited mass transfer, and poor denitrification efficiency caused by insufficient carrier surface area. Combined with the inherent conductive properties of conductive carriers (such as conductive carbon fibers and glass fibers), the high specific surface area of ​​the carrier can more uniformly and efficiently transfer electrons to the attached microorganisms, especially hydrogen autotrophic denitrifying bacteria, thereby significantly enhancing the overall denitrification performance of the electrobiofilm. This allows nitrates and nitrites in wastewater to be reduced to harmless nitrogen more efficiently and thoroughly, thereby improving the efficiency and stability of wastewater denitrification treatment and reducing treatment costs.

[0063] In some implementations, the electrobiofilm achieves wastewater denitrification through a coupled bacterial layer formed on the surface of a conductive carrier, which contains various denitrifying bacteria. However, in actual wastewater treatment processes, especially when treating high-salinity wastewater, the coupled bacterial layer may face problems such as reduced biological activity, bacterial loss, and poor biofilm structural stability, thereby affecting the overall denitrification efficiency and long-term operational stability.

[0064] In some embodiments, the electrobiofilm further includes a coating layer located between the conductive carrier and the coupled bacterial layer. The coating comprises alginate and salt-tolerant denitrifying bacteria, wherein the inoculum amount of the salt-tolerant denitrifying bacteria is 15 g / m³. 3 ~25g / m 3 .

[0065] The coating is designed to sit between the conductive carrier and the coupled bacterial layer, serving as an interface layer between the two. This coating enhances the adhesion of the coupled bacterial layer to the conductive carrier, providing a more stable growth environment for the microorganisms and potentially acting as a barrier to protect them from adverse environmental factors. The coating can be formed by impregnation, spraying, or brushing to ensure uniform coverage of the conductive carrier surface. The coating contains alginate, a natural polysaccharide with good biocompatibility and gel-forming ability. In the coating, alginate primarily acts as a biomatrix, forming a porous gel structure that provides physical support and protection for the microorganisms. This gel structure helps maintain microbial activity and promotes the diffusion of nutrients and metabolites. Alginate is typically used in its sodium salt form, forming a gel by cross-linking with divalent cations such as calcium ions. The coating also contains salt-tolerant denitrifying bacteria. Salt-tolerant denitrifying bacteria are microorganisms capable of denitrification in high-salinity environments. Pre-inoculating these bacteria into the coating aims to improve the adaptability and treatment capacity of the electrobiofilm for high-salinity wastewater. These microbial strains are protected to some extent within the coating and initiate the denitrification process first under high-salt conditions, laying the foundation for the stable operation of the subsequent coupled bacterial layer. The types of salt-tolerant denitrifying bacteria can include, but are not limited to, certain strains of *Pseudomonas*, *Desulfovibrio*, or *Bacillus*, which have been shown to have strong salt tolerance. The inoculum size of salt-tolerant denitrifying bacteria is limited to 15 g / m³. 3 ~25g / m 3 Within a certain range. This inoculum amount refers to the biomass of salt-tolerant denitrifying bacteria added per unit volume (usually the reactor volume or the volume of the treatment medium) during coating preparation. This range is set to ensure a sufficient number of active bacteria in the coating to quickly establish effective nitrogen removal, while avoiding problems such as excessively thick biofilms, limited mass transfer, or increased costs due to excessive bacterial count.

[0066] The above technical solution involves placing a coating containing alginate and salt-tolerant denitrifying bacteria between the conductive carrier and the coupled bacterial layer. Alginate, as a biocompatible matrix, effectively enhances the adhesion between the coupled bacterial layer and the conductive carrier, improves the structural stability of the biofilm, and reduces bacterial loss. Simultaneously, the salt-tolerant denitrifying bacteria pre-inoculated in the coating can rapidly adapt to the environment and initiate the denitrification process even in high-salinity wastewater conditions, providing a stable foundation for the subsequent formation and function of the coupled bacterial layer. This not only improves the denitrification efficiency and stability of the electrobiofilm in high-salinity wastewater treatment but also ensures the long-term reliable operation of the entire denitrification system.

[0067] While electrobiofilms containing specific bacterial communities and conductive carriers can be designed for wastewater denitrification, the key challenge in realizing their application lies in efficiently and stably inoculating and culturing various functional bacterial communities, such as hydrogen autotrophic denitrifying bacteria, sulfur autotrophic denitrifying bacteria, and heterotrophic denitrifying bacteria, onto the surface of a conductive carrier to form a coupled bacterial layer with good denitrification performance. Traditional biofilm cultivation methods struggle to precisely control the growth environment and synergistic effects of different bacterial communities, potentially leading to low biofilm formation efficiency or unstable denitrification results.

[0068] For this, please refer to Figure 1 As shown, this application also provides a method for preparing the above-mentioned electrobiofilm for wastewater denitrification treatment. This method, through a step-by-step process, aims to effectively construct an electrobiofilm with a multifunctional coupled bacterial layer. The preparation method includes the following steps:

[0069] S100, Inoculation Step: The conductive carrier is placed in the biological treatment tank, and anaerobic sludge and a carbon source are introduced. The anaerobic sludge includes both hydrogen autotrophic and heterotrophic denitrifying bacteria. The purpose of this step is to provide the basic microbial species and growth environment for the initial formation of the electrobiofilm. By placing the conductive carrier (e.g., conductive carbon fiber or glass fiber) in the biological treatment tank and introducing anaerobic sludge containing hydrogen autotrophic denitrifying bacteria (such as *Paracococcus denitrifyingus*, *Alcaligenes*, and hydrogen phages) and heterotrophic denitrifying bacteria (such as *Pseudomonas*, *Desulfovibrio*, and *Bacillus*), the rich microbial resources in the anaerobic sludge can be utilized to initiate the initial growth of the biofilm on the surface of the conductive carrier. Simultaneously, the introduction of a carbon source (e.g., sodium acetate, glucose, methanol, etc.) provides the necessary electron donors and carbon source for the heterotrophic denitrifying bacteria, promoting their growth and activity. The biological treatment tank must provide a suitable anaerobic environment to facilitate the growth of anaerobic bacteria. The conductive carrier should be placed evenly in the biological treatment tank to ensure full contact with the sludge and carbon source.

[0070] S200, the activation process, involves electrically connecting the conductive carrier to a DC power supply to initiate the cathodic hydrogen evolution reaction. This step is crucial for the formation of the electrobiofilm. By applying an external DC electric field, the cathodic hydrogen evolution reaction is triggered on the surface of the conductive carrier, generating hydrogen gas. Hydrogen gas, acting as an electron donor for hydrogen autotrophic denitrifying bacteria, specifically promotes their accumulation and growth on the conductive carrier surface, thus providing efficient hydrogen autotrophic denitrification capacity for subsequent nitrogen removal processes. The DC power supply provides a stable DC current, the voltage and current of which need to be adjusted according to the characteristics of the conductive carrier and the scale of the biological treatment tank. The conductive carrier, acting as the cathode, is connected to the negative terminal of the DC power supply, while an anode is typically installed in the biological treatment tank and connected to the positive terminal of the DC power supply, forming a complete electrical circuit. The activation process usually needs to continue for a period of time to ensure sufficient hydrogen production and effective accumulation of hydrogen autotrophic denitrifying bacteria.

[0071] S300, the acclimatization process involves adding sulfur-autotrophic denitrifying bacteria, a sulfur source, and a pH adjuster to the biological treatment tank, and increasing the current to 200A-250A to form a coupled bacterial layer on the surface of the conductive carrier, resulting in an electrobiofilm. The acclimatization process aims to further refine the composition and function of the coupled bacterial layer, introduce sulfur-autotrophic denitrifying bacteria, and optimize environmental conditions to promote the synergistic effect of all bacterial communities, ultimately forming a stable and efficient electrobiofilm. Sulfur-autotrophic denitrifying bacteria (such as Thiobacillus, Thiobacillus microspirilla, and Dethiobacillus) can utilize sulfides as electron donors for denitrification. The addition of a sulfur source (such as sodium thiosulfate or sodium sulfide) provides the necessary electron donor for the sulfur-autotrophic denitrifying bacteria. Since hydrogen evolution at the cathode produces hydroxide ions, which may cause a local pH increase, a pH adjuster (such as sodium bicarbonate or acid) needs to be added to maintain the pH in the biological treatment tank within a suitable range to ensure optimal activity of all bacterial communities. Increasing the current to 200A~250A can increase the hydrogen evolution rate at the cathode, providing more electron donors for hydrogen autotrophic denitrifying bacteria. It may also enhance the influence of the electric field on microbial attachment and biofilm structure, promoting biofilm densification and functionalization. The acclimation process is a gradual optimization process, requiring monitoring of various parameters within the biological treatment tank and adjusting the dosage and current based on the monitoring results until a stable coupled bacterial layer is formed.

[0072] Through a step-by-step inoculation, activation, and acclimatization process, this method can precisely control the growth environment and enrichment process of different functional bacterial communities. The inoculation process provides basic bacterial species and carbon sources for the initial formation of the biofilm, laying the foundation for heterotrophic and hydrogen autotrophic denitrification capabilities. The activation process, by initiating a cathodic hydrogen evolution reaction on the conductive carrier surface, specifically provides sufficient electron donors for hydrogen autotrophic denitrifying bacteria, thereby efficiently promoting their enrichment and growth on the carrier surface and ensuring the effective establishment of the hydrogen autotrophic denitrification pathway. The acclimatization process further introduces sulfur autotrophic denitrifying bacteria and, by adding sulfur sources and pH adjusters, provides suitable growth conditions and electron donors for them, while optimizing the overall biological tank environment. This allows hydrogen autotrophic, sulfur autotrophic, and heterotrophic denitrifying bacteria to work synergistically, forming a structurally stable and functionally complete coupled bacterial layer on the conductive carrier surface. This controlled cultivation strategy significantly improves the formation efficiency and stability of electrobiofilms, ensuring the effective integration of multiple denitrification pathways, thereby achieving efficient and continuous removal of nitrogen from wastewater. It overcomes the challenges of traditional methods in constructing complex biofilms and provides a guarantee for the long-term stable operation of electrobiofilms.

[0073] In the aforementioned method for preparing electrobiofilms, the inoculation step only mentions placing the conductive carrier in a biological tank and adding anaerobic sludge and a carbon source, and the acclimatization step involves adding sulfur-autotrophic denitrifying bacteria, a sulfur source, and a pH adjuster. However, a lack of precise control over the amount of anaerobic sludge added, the type of carbon source, the amount of sulfur source added, and the pH adjuster may lead to low microbial inoculation efficiency, affecting the rapid formation and stable growth of the biofilm, and consequently impacting the overall nitrogen removal performance of the electrobiofilm.

[0074] In this regard, this application further proposes that, in order to optimize the inoculation and acclimatization process of microorganisms in the above-mentioned preparation method, the amount of anaerobic sludge added in the inoculation step is set to 15%~25% based on the volume of the biological treatment tank. This amount ensures that a sufficient number of microorganisms can attach and begin to grow in the initial stage, thereby accelerating the formation of the coupled bacterial layer on the surface of the conductive carrier. Anaerobic sludge, as the initial bacterial source, usually contains a variety of microorganisms, among which hydrogen autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria are key components, and their appropriate addition is crucial for establishing a stable microbial community.

[0075] In addition, the carbon source can include sodium acetate. Sodium acetate, as an easily biodegradable organic carbon source, can provide sufficient electron donors and carbon sources for heterotrophic denitrifying bacteria, promoting their rapid proliferation and activity maintenance in the coupled bacterial layer. This is of great significance for ensuring the effective contribution of heterotrophic denitrifying bacteria in the nitrogen removal process.

[0076] Furthermore, the sulfur source can include sodium thiosulfate, and its addition amount is precisely controlled within the range of 2160 g / d to 4320 g / d. Sodium thiosulfate, as an electron donor for sulfur-autotrophic denitrifying bacteria, is crucial for maintaining the activity and quantity of these bacteria. By controlling its addition amount, the decrease in nitrogen removal efficiency due to insufficient sulfur source can be avoided, while the inhibitory effect that may be caused by excessive sulfur source can also be prevented, thus providing an optimal growth environment for sulfur-autotrophic denitrifying bacteria.

[0077] Simultaneously, pH adjusters can include sodium bicarbonate, and its addition amount is equal to that of the sulfur source, to maintain the pH in the biological treatment tank within the range of 7.0–8.0. Sodium bicarbonate, as an effective buffer, can neutralize acidic substances produced during microbial metabolism, stabilizing the pH value in the biological treatment tank. Linking the amount of pH adjuster added to the amount of sulfur source added is based on a thorough understanding of the pH changes that may be caused by sulfur autotrophic denitrification, ensuring that while sulfur autotrophic denitrifying bacteria are active, the pH in the biological treatment tank remains within the optimal growth and reaction range for microorganisms.

[0078] By employing the aforementioned technical solutions, precisely controlling the amount of anaerobic sludge input, selecting efficient carbon and sulfur sources, and combining a refined pH adjustment strategy, this application significantly optimizes the preparation process of the electrobiofilm. The synergistic effect of these parameters ensures that hydrogen autotrophic denitrifying bacteria, sulfur autotrophic denitrifying bacteria, and heterotrophic denitrifying bacteria can rapidly and stably form a highly active coupled bacterial layer on the conductive carrier surface. This not only improves the biofilm inoculation success rate and formation speed but also guarantees the structural and functional stability of the microbial community, resulting in a more superior and durable denitrification performance of the prepared electrobiofilm in wastewater denitrification treatment. This refined preparation method effectively solves the problems of low biofilm formation efficiency and unstable denitrification effect caused by improper parameter control in traditional methods, providing a solid technical foundation for efficient wastewater denitrification treatment.

[0079] In the preparation of electrobiofilms for wastewater denitrification, a conductive carrier is typically placed in a biological treatment tank, and a coupled bacterial layer is formed on its surface through inoculation, activation, and acclimatization processes. However, directly inoculating microorganisms onto the exposed surface of the conductive carrier may result in problems such as low initial microbial attachment efficiency, slow biofilm formation rate, and insufficient stability of the biofilm in complex water quality environments, thus affecting the overall performance and service life of the electrobiofilm.

[0080] In some embodiments, a pretreatment step is included prior to the inoculation step described above. This pretreatment step aims to optimize the surface of the conductive carrier to promote the formation and stabilization of the subsequent coupled bacterial layer.

[0081] Specifically, the pretreatment process includes immersing a conductive carrier in an alginate solution to form a coating on the surface of the carrier. The conductive carrier may include one or more of conductive carbon fibers and glass fibers, serving as a substrate for microbial attachment and growth, and providing an electrochemical reaction interface. The alginate solution is typically prepared by dissolving sodium alginate in deionized water or a buffer solution, and its concentration can be adjusted according to the desired coating thickness and strength; for example, a 1% to 5% (w / v) sodium alginate solution may be prepared. Immersing the conductive carrier in this solution allows the alginate to be uniformly adsorbed or coated onto the surface of the conductive carrier. The immersion time can be adjusted according to the porosity of the carrier material and the solution concentration to ensure the formation of a uniform coating with sufficient thickness. After immersion, the alginate-coated conductive carrier is typically removed and may be further immersed in a crosslinking agent containing divalent cations (such as calcium chloride solution) to gel the alginate, thereby forming a stable hydrogel coating on the surface of the conductive carrier. This coating serves as the interface between the conductive carrier and the coupled bacterial layer, providing a more hydrophilic, porous, and biocompatible attachment environment for microorganisms.

[0082] By employing the aforementioned technical solution, pre-forming an alginate coating on the surface of the conductive carrier significantly improves the initial attachment conditions for microorganisms, providing a more stable and favorable microenvironment for the subsequent formation of the coupled bacterial layer. The alginate coating possesses excellent biocompatibility and a porous structure, which helps improve the inoculation efficiency of microorganisms and the growth rate of the biofilm. Simultaneously, it provides a certain degree of protection for microorganisms, enhancing the biofilm's resilience in complex wastewater environments. This not only accelerates the maturation process of the electrobiofilm but also improves its stability and denitrification performance during long-term operation. Furthermore, this coating can also serve as a slow-release carrier for microorganisms, further optimizing the structure and function of the biofilm.

[0083] In some embodiments, the method includes an inoculation step, an activation step, and an acclimatization step. In the activation step, an electron donor is provided to hydrogen autotrophic denitrifying bacteria by electrically connecting a conductive carrier to a DC power source to initiate a cathode hydrogen evolution reaction. However, in practice, if the anaerobic sludge in the biological treatment tank is in a relatively static environment, insufficient contact between the microorganisms and the surface of the conductive carrier, as well as the evolved hydrogen, may occur, affecting the enrichment efficiency and activity of the hydrogen autotrophic denitrifying bacteria, thereby delaying the formation rate and quality of the coupled bacterial layer.

[0084] In some embodiments, anaerobic sludge is returned to the biological treatment tank through pipelines, and the anaerobic sludge return ratio is 200%~400%, with a anaerobic sludge return velocity greater than or equal to 0.35m / s.

[0085] Specifically, the return of anaerobic sludge to the biological treatment tank via pipelines refers to the process of transporting some or all of the anaerobic sludge from the biological treatment tank back into the tank through an external pipeline system. This aims to break the static or low-dynamic state of the fluid within the biological treatment tank. On the one hand, forced circulation promotes uniform mixing of the anaerobic sludge, ensuring that microorganisms can more frequently and fully contact the surface of the conductive carrier and the hydrogen gas evolved from the cathode. This is crucial for the growth and enrichment of hydrogen autotrophic denitrifying bacteria that rely on hydrogen as an electron donor, effectively improving the mass transfer efficiency and reaction rate of microorganisms. On the other hand, it also reduces the occurrence of crystallization and scaling on the surface of the conductive carrier.

[0086] Based on this, the anaerobic sludge return ratio is controlled within the range of 200% to 400%. The return ratio refers to the ratio of the amount of sludge returned to the influent entering the biological treatment tank. This high return ratio ensures that a high concentration of microorganisms is maintained within the biological treatment tank, and that the fluids within the tank are strongly mixed. A high return ratio helps dilute inhibitory substances in the influent, stabilizes the environmental conditions within the biological treatment tank, and provides sufficient reaction time for microorganisms, thereby optimizing the growth environment and activity of hydrogen autotrophic denitrifying bacteria. Furthermore, controlling the return ratio within the above range helps reduce the occurrence of crystallization and scaling on the conductive carrier surface.

[0087] Meanwhile, the anaerobic sludge return velocity is greater than or equal to 0.35 m / s. The anaerobic sludge return velocity refers to the speed at which the sludge flows in the return pipeline. Setting the return velocity to greater than or equal to 0.35 m / s aims to provide sufficient shear force and mixing intensity. A higher velocity effectively prevents sludge settling at the bottom of the pipeline or biological treatment tank, maintaining the sludge in suspension and ensuring uniform distribution of microorganisms throughout the entire biological treatment tank. Furthermore, an appropriate velocity also helps enhance mass transfer, allowing hydrogen to diffuse more effectively to the surface of microbial cells, thereby improving the hydrogen utilization efficiency of hydrogen autotrophic denitrifying bacteria.

[0088] By introducing anaerobic sludge recirculation into the pipeline during the activation process and precisely controlling the recirculation ratio within the range of 200% to 400%, as well as the recirculation velocity greater than or equal to 0.35 m / s, this application significantly improves the hydraulic conditions and mass transfer efficiency within the biological treatment tank. This dynamic mixing environment ensures that the hydrogen autotrophic denitrifying bacteria in the anaerobic sludge can achieve sufficient and uniform contact with the conductive carrier surface and the hydrogen gas evolved from the cathode, thereby overcoming the problem of insufficient microbial contact under static activation conditions. The high recirculation ratio and suitable flow velocity not only promote the uniform distribution and enrichment of microorganisms but also accelerate the effective utilization of hydrogen gas, providing favorable conditions for the rapid growth of hydrogen autotrophic denitrifying bacteria and the formation of coupled bacterial layers. Therefore, this application can effectively improve the preparation efficiency of electrobiofilms, shorten the acclimation period, and ultimately obtain electrobiofilms with higher activity and stronger stability, thereby improving the performance of wastewater denitrification treatment.

[0089] The following is a more specific example to illustrate the technical solution in greater detail:

[0090] In an industrial application scenario involving the treatment of stripping wastewater, the total nitrogen concentration in the wastewater is at a high level, resulting in an imbalanced carbon-to-nitrogen ratio. An electrobiofilm technology is employed to remove nitrogen from the wastewater.

[0091] The electrobiofilm consists of a conductive carrier and a coupled bacterial layer. The conductive carrier is a combination of conductive carbon fiber and glass fiber, with a volumetric surface area controlled at 500 m². 2 / m 3 up to 1000m 2 / m 3 Within a certain range, it provides space for microbial attachment and a conductive path. A pre-formed coating is formed on the surface of the conductive carrier, consisting of alginate and salt-tolerant denitrifying bacteria, with an inoculum amount of 15 g / m². 3 Up to 25g / m 3 The coating improves the stability of biofilms and enhances their adaptability to high-salt environments.

[0092] The coupled bacterial layer adheres to the outer side of the coating, with functional bacterial communities working synergistically. Autotrophic denitrifying bacteria are a component, including hydrogen autotrophic and sulfur autotrophic denitrifying bacteria. Hydrogen autotrophic denitrifying bacteria, such as *Paracococcus denitrifyingus*, *Alcaligenes*, and hydrogen phages, achieve nitrogen removal rates ranging from 30% to 60%. They utilize hydrogen generated from hydrogen evolution at the cathode of the conductive carrier as an electron donor to reduce nitrate nitrogen in wastewater to nitrogen gas, achieving denitrification without relying on additional organic carbon sources. Sulfur autotrophic denitrifying bacteria, such as *Thiobacillus*, *Thiospirillum thiocyanate*, and *Dethiobacillus*, achieve nitrogen removal rates ranging from 20% to 40%. They utilize sulfides as electron donors for denitrification, broadening the sources of electron donors. The coupled bacterial layer also includes heterotrophic denitrifying bacteria, such as *Pseudomonas*, *Dethioviolacea*, and *Bacillus*, which utilize the small amounts of organic carbon sources present in the wastewater for denitrification, forming a complementary denitrification system.

[0093] The preparation process of the electrobiomembrane includes the following steps:

[0094] Pretreatment process: The conductive carrier composed of conductive carbon fiber and glass fiber is immersed in alginate solution to form a coating on its surface.

[0095] Inoculation process: The conductive carrier is placed in the biological treatment tank, and anaerobic sludge and carbon source are added. The anaerobic sludge contains both hydrogen autotrophic and heterotrophic denitrifying bacteria, and the amount added is controlled at 15%~25% based on the volume of the biological treatment tank. Sodium acetate is selected as the carbon source for initial culture and heterotrophic bacteria growth.

[0096] Activation process: The conductive carrier is electrically connected to a DC power supply, initiating the hydrogen evolution reaction at the cathode. During this process, the anaerobic sludge is returned to the biological treatment tank through pipelines at a return ratio of 200%~400% and a return flow rate greater than or equal to 0.35m / s.

[0097] Acclimation process: Sulfur-autotrophic denitrifying bacteria, a sulfur source, and a pH adjuster are added to the biological treatment tank. Sodium thiosulfate is used as the sulfur source, with an addition rate of 2160 g / d to 4320 g / d. Sodium bicarbonate is used as the pH adjuster, added in an amount equal to that of the sulfur source, maintaining the pH in the biological treatment tank within the range of 7.0 to 8.0. Simultaneously, the current is increased to 200 A to 250 A to promote the formation of the coupled bacterial layer on the surface of the conductive carrier, ultimately obtaining an electrobiofilm for wastewater denitrification treatment.

[0098] This technology removes high concentrations of nitrate and ammonia nitrogen from stripping wastewater using an electrobiofilm. Compared to traditional denitrification processes, this solution reduces reliance on external organic carbon sources. Traditional processes, when treating stripping wastewater with an imbalanced carbon-to-nitrogen ratio, require the addition of organic carbon sources such as sodium acetate or methanol, resulting in high operating costs. This electrobiofilm utilizes hydrogen generated from hydrogen evolution at the cathode by hydrogen autotrophic denitrifying bacteria, and sulfur-autotrophic denitrifying bacteria utilize sulfur sources, providing electron donors for non-organic carbon and enabling denitrification in a carbon-scarce environment. This multi-pathway, combined autotrophic and heterotrophic nitrogen removal mechanism solves the problem of high total nitrogen and low carbon-to-nitrogen ratio in stripping wastewater, reduces treatment costs, and represents a significant advancement in technology.

[0099] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0100] Example 1

[0101] This embodiment provides a method for preparing an electrobiomembrane, comprising the following steps:

[0102] A conductive carrier composed of conductive carbon fiber and glass fiber is immersed in a 5 wt% alginate solution to form a coating on its surface.

[0103] The aforementioned conductive carrier was placed in a biological treatment tank, and anaerobic sludge and sodium acetate were added. The anaerobic sludge contained denitrifying paracocci and pseudomonads, and the amount added was controlled at 20% of the volume of the biological treatment tank.

[0104] The conductive carrier is then connected to a DC power supply with an initial current of 100A to initiate the hydrogen evolution reaction at the cathode. During this process, the anaerobic sludge is returned to the biological treatment tank through pipelines at a return ratio of 300% and a return flow rate of 0.35m / s.

[0105] Desulfuric bacteria, sodium thiosulfate, and sodium bicarbonate (a pH adjuster) were added to the biological treatment tank. The initial addition of sodium thiosulfate was 2160 g / d, increasing by 500 g every 3 days to the desired value of 4320 g / d. The amount of pH adjuster added was equal to that of sodium thiosulfate, maintaining the pH in the biological treatment tank within the range of 7.0 to 8.0. Simultaneously, the current was increased to 250 A to promote the formation of the coupled bacterial layer on the surface of the conductive carrier, ultimately obtaining an electrobiofilm for wastewater denitrification treatment.

[0106] The wastewater generated from the stripping process is fed into the aforementioned biological treatment tank for denitrification treatment. The total nitrogen concentration in the wastewater is 1100 mg / L, and the carbon-to-nitrogen ratio is 1.5.

[0107] Example 2

[0108] The difference between this embodiment and Embodiment 1 is that Alcaligenes is used instead of Paracoccus denitrifyingis.

[0109] Example 3

[0110] The difference between this embodiment and Embodiment 1 is that hydrogen phage is used instead of paranitrococcus denitrification.

[0111] Example 4

[0112] The difference between this embodiment and Embodiment 1 is that Thiobacillus is used instead of Desulfurobacillus.

[0113] Example 5

[0114] The difference between this embodiment and Embodiment 1 is that: Thiospirobacterium thiocyanate is used instead of Desulfobacterium thiocyanate.

[0115] Example 6

[0116] The difference between this embodiment and embodiment 4 is that desulfovibrio is used instead of pseudomonas.

[0117] Example 7

[0118] The difference between this embodiment and Embodiment 4 is that Bacillus is used instead of Pseudomonas.

[0119] Comparative Example 1

[0120] The difference between this comparative example and Example 1 is that a mixed gas containing acetylene, an inhibitor of hydrogen autotrophic bacteria, is introduced into the biochemical tank, wherein the mass content of acetylene in the mixed gas is 5%.

[0121] Comparative Example 2

[0122] The difference between this comparative example and Example 1 is that sodium molybdate, a sulfur-containing autotrophic bacteria inhibitor, was added to the biochemical tank to achieve a mass concentration of 2 mM.

[0123] Table 1 lists the test results of Examples 1 to 7 and Comparative Examples 1 to 2.

[0124] Table 1

[0125]

[0126] According to Table 1, comparing the test results of Examples 1 to 7 and Comparative Examples 1 to 2, it can be seen that the coupled bacterial layer includes autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria. Among them, the autotrophic denitrifying bacteria include hydrogen autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria. By combining autotrophic denitrifying bacteria, electron donors are provided through electrochemical processes to achieve efficient nitrogen removal without relying on a high carbon-nitrogen ratio. It has the ability to efficiently remove nitrogen under low carbon-nitrogen ratio conditions.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this specification, and not to limit them. Although this specification has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments in this specification.

Claims

1. An electrobiofilm for wastewater denitrification treatment, characterized in that, This electrobiomembrane includes: Conductive carrier; and A coupled bacterial layer is located on the surface of a conductive carrier. The coupled bacterial layer includes autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria, wherein the autotrophic denitrifying bacteria include hydrogen autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

2. The electrobiofilm for wastewater denitrification treatment according to claim 1, characterized in that, The denitrification rate of the hydrogen autotrophic denitrifying bacteria is in the range of 30% to 60%. And / or, the nitrogen removal rate of the sulfur autotrophic denitrifying bacteria is 20% to 40%.

3. The electrobiofilm for wastewater denitrification treatment according to claim 1, characterized in that, The hydrogen autotrophic denitrifying bacteria include one or more of Paracoccus denitrifying, Alcaligenes, and hydrogen phages; And / or, the sulfur autotrophic denitrifying bacteria include one or more of Thiobacillus, Thiospirillum, and Dethiobacillus; And / or, the heterotrophic denitrifying bacteria include one or more of Pseudomonas, Desulfovibrio, and Bacillus.

4. The electrobiofilm for wastewater denitrification treatment according to claim 1, characterized in that, The conductive carrier includes one or more of conductive carbon fibers and glass fibers.

5. The electrobiofilm for wastewater denitrification treatment according to claim 4, characterized in that, The specific surface area of ​​the conductive carrier is 500 m². 2 / m 3 ~1000m 2 / m 3 .

6. The electrobiofilm for wastewater denitrification treatment according to claim 1, characterized in that, Also includes: A coating, located between the conductive carrier and the coupled bacterial layer, comprises alginate and salt-tolerant denitrifying bacteria, wherein the inoculum amount of the salt-tolerant denitrifying bacteria is 15 g / m³. 3 ~25g / m 3 .

7. A method for preparing an electrobiofilm for wastewater denitrification treatment as described in any one of claims 1 to 6, characterized in that, The preparation method includes: Inoculation process: The conductive carrier is placed in the biological tank, and anaerobic sludge and carbon source are added to the biological tank, wherein the anaerobic sludge includes hydrogen autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria; Activation process: The conductive carrier is electrically connected to a DC power supply to initiate the cathode hydrogen evolution reaction; Domestication process: Sulfur autotrophic denitrifying bacteria, sulfur source and pH adjuster are added to the biochemical tank, and the current is increased to 200A~250A to form a coupled bacterial layer on the surface of the conductive carrier to obtain an electrobiofilm.

8. The preparation method according to claim 7, characterized in that, In the inoculation process, based on the volume of the biological treatment tank, the amount of anaerobic sludge added is 15% to 25%; And / or, the carbon source includes sodium acetate; And / or, the sulfur source includes sodium thiosulfate, and the amount of sulfur source added is 2160g~4320g / d; And / or, the pH adjuster includes sodium bicarbonate, and the amount of the pH adjuster added is equal to the amount of the sulfur source added, so as to keep the pH in the biological tank at 7.0~8.

0.

9. The preparation method according to claim 7, characterized in that, Also includes: Pretreatment step: Immerse the conductive carrier in an alginate solution to form a coating on the surface of the conductive carrier.

10. The preparation method according to any one of claims 7 to 9, characterized in that, In the activation process, the anaerobic sludge is returned to the biological treatment tank through a pipeline, and the return ratio of the anaerobic sludge is 200%~400%, and the flow rate of the anaerobic sludge return is greater than or equal to 0.35m / s.

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