Electroactive material, method for preparing the same and use thereof

Abstract

The application relates to the technical field of electroactive materials, in particular to an electroactive material and a preparation method and application thereof. The application provides a preparation method of an electroactive material, which comprises the following steps: dissolving a pore-forming agent, an iron salt and a manganese salt in a sugar solution, initiating a hydrothermal reaction to obtain a hydrothermal product; and high-temperature carbonizing the hydrothermal product in an oxygen-free environment to obtain an iron-manganese-carbon electroactive material. The application provides an electroactive material and a preparation method and application thereof, and the electroactive material can still have high nitrogen and phosphorus removal efficiency in a low-temperature environment.

Description

Technical Field

[0001] This invention relates to the field of electroactive materials technology, and in particular to an electroactive material, its preparation method, and its application. Background Technology

[0002] Biological nitrogen and phosphorus removal processes in wastewater are crucial for ensuring water environment safety and supporting the operation of wastewater treatment plants. Currently, the commonly used activated sludge process removes nitrogen through aerobic nitrification and anoxic denitrification, while phosphorus is released and excessively absorbed by polyphosphate-accumulating bacteria in an alternating anaerobic / aerobic environment. However, this process is highly sensitive to temperature. In northern my country, especially the northeast, the influent temperature is consistently below 15°C from October to April of the following year, far below the optimal temperature (~35°C) for most functional microorganisms. This inhibits nitrification, denitrification, and the activity of polyphosphate-accumulating bacteria, resulting in a significant decrease in nitrogen and phosphorus removal efficiency. Summary of the Invention

[0003] This invention provides an electroactive material, its preparation method, and its application. It can provide an electroactive material that still has a high nitrogen and phosphorus removal efficiency when used in a low-temperature environment.

[0004] In a first aspect, embodiments of the present invention provide a method for preparing an electroactive material, comprising: A pore-forming agent, iron salt, and manganese salt are dissolved in a sugar solution to initiate a hydrothermal reaction, yielding a hydrothermal product. The hydrothermal products were carbonized at high temperature in an oxygen-free environment to obtain an iron-manganese-carbon electroactive material.

[0005] Optionally, the pore-forming agent includes urea, the iron salt includes ferric chloride, the manganese salt includes manganese chloride, and the sugar solution includes an aqueous glucose solution.

[0006] Optionally, the amount of solute added to the pore-forming agent and the sugar solution is 120~180g / L, the C:Fe molar ratio of sugar in the sugar solution to iron in the iron salt is (10~20):1, and the Fe:Mn molar ratio of iron salt to manganese salt is (1~3):1. The hydrothermal reaction is carried out at a temperature of 180-200℃ for 12-14 hours.

[0007] Optionally, the process parameters for high-temperature carbonization include: a heating rate of 5~10℃ / min, a carbonization temperature of 800~900℃, and a carbonization time of 0.5~1 h.

[0008] Optionally, after obtaining the iron-manganese-carbon electroactive material, the method further includes: The obtained iron-manganese-carbon electroactive material was loaded onto a sponge.

[0009] Optionally, the sponge is a polyurethane sponge, the loading agent is a water-soluble polyurethane solution, and the density of the sponge is 30~35 kg / m³. 3 .

[0010] Secondly, embodiments of the present invention also provide an electroactive material prepared according to any of the preparation methods described above.

[0011] Thirdly, embodiments of the present invention also provide an application of an electroactive material, wherein the application, based on any of the above-mentioned electroactive materials, includes: During the sludge acclimatization stage, the reactor was initially continuously aerated, and then the aeration was adjusted to intermittent aeration to enhance the system's simultaneous nitrification and denitrification capabilities. During the normal temperature operation phase, the electroactive material is introduced into the reactor, and the aeration is changed to a continuous repeating pre-anaerobic + intermittent aeration mode to establish a sludge-biofilm synergistic system. During the low-temperature operation phase, when the temperature drops to 12~17℃, the aeration frequency of the intermittent aeration section in the aeration mode is increased.

[0012] Optionally, the sludge acclimatization stage includes 27 days, with continuous aeration for the first 8 days and a 10-minute aeration / 10-minute rest period starting from the 9th day. The ambient temperature operation phase includes days 28 to 83, and the aeration mode includes 0.5 to 1 h of pre-anaerobic treatment + 4 to 5 h of intermittent aeration. The frequency of intermittent aeration is 10 min aeration / 10 min rest. The low-temperature operation phase includes days 84 to 105, and the aeration mode includes 0.5 to 1 h of pre-anaerobic treatment + 4 to 5 h of intermittent aeration. The frequency of intermittent aeration is 25 to 35 seconds of aeration / 40 to 50 seconds of rest. The aeration rate of the reactor is controlled within the range of 40~100 mL / min to maintain the dissolved oxygen concentration of the system between 0.3~1.0 mg / L.

[0013] Optionally, the filling volume of the electroactive material is 20-40% of the reactor cavity volume.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: 1. High-efficiency low-temperature synergistic nitrogen and phosphorus removal: The electroactive carrier-enhanced low-temperature simultaneous nitrogen and phosphorus removal method and system constructed in this invention can achieve high-efficiency simultaneous nitrogen and phosphorus removal under ambient to low-temperature conditions in a single reactor. The system requires no additional heating device, has low energy consumption during the reaction process, and is simple to construct, which can significantly reduce the operating cost of wastewater treatment in cold regions.

[0015] 2. Multifunctional Electroactive Carrier Enhances Electron Behavior and Nitrogen Conversion: The electroactive carrier involved in this invention possesses a negative surface charge, electrochemical capacitance, and redox active sites, which can enhance the surface adsorption of ammonia nitrogen, promote extracellular electron transfer, and simultaneously absorb trace amounts of Mn. 2+ The release of these molecules can serve as an inorganic electron donor, enhancing the synergistic efficiency of nitrification and denitrification processes.

[0016] 3. Optimize the surface and promote microbial enrichment: The electroactive carrier has a rich porous structure and excellent hydrophilicity, which promotes the attachment and reproduction of microorganisms on the carrier surface, forming a stable sludge film symbiotic structure and enhancing the structural stability of sludge.

[0017] 4. Multidimensional biological synergistic mechanism enhances system stability: The synchronous nitrogen and phosphorus removal system constructed based on electroactive carriers realizes multidimensional coupling between nitrogen and phosphorus conversion, electron transport, and microorganisms related to biofilm formation, promotes the synergistic regulation of extracellular electron transport and quorum sensing-related genes, and achieves stable operation of the system at low temperatures. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a low-temperature synchronous nitrogen and phosphorus removal system based on electroactive carrier enhancement in this invention; Figure 2 Electrochemical performance graphs, including: Figure 2 (a) Cyclic voltammetry curves of iron, manganese and carbon at different scan rates; Figure 2 (b) is a graph showing the linear relationship between the peak current of iron, manganese, and carbon and the logarithm of the scan rate; Figure 2 (c) is a graph showing the linear relationship between the peak current of iron, manganese and carbon and the square root of the scan rate; Figure 2 (d) shows the cyclic voltammetry curves of iron and carbon at different scan rates; Figure 2 (e) is a graph showing the linear relationship between the peak current of iron and carbon and the logarithm of the scan rate; Figure 2 (f) is a graph showing the linear relationship between the peak current of iron and carbon and the square root of the scan rate; Figure 3 The DO value for the system operating at 15°C; Figure 4 The electron transport system activity of different reaction systems after operation at 15°C; Figure 5 Comparative diagrams of bioaccumulation over long-term operation of different reaction systems, including: Figure 5 (a) is a photo taken before use on a regular carrier; Figure 5 (b) is a photograph of the iron-carbon electroactive carrier before use. Figure 5 (c) is a photograph of the iron-manganese-carbon electroactive carrier before use; Figure 5 (d) is a photo taken after using a regular medium; Figure 5 (e) is a photograph of the iron-carbon electroactive carrier after use. Figure 5 (f) is a photograph of the iron-manganese-carbon electroactive carrier after use; Figure 5 (g) is an electron microscope image of a normal carrier after use; Figure 5 (h) is an electron microscope image of the iron-manganese-carbon electroactive carrier after use.

[0020] The labels in the attached diagram are: 1-Inlet substrate, 2-Inlet pump, 3-Stirring system, 4-pH and DO testing system, 5-Outlet pump, 6-Gas flow meter, 7-Aeration pump, 8-Microporous aeration disc, 9-Electroactive carrier, 10-Time control system. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] In the description of the embodiments of the present invention, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0023] In this specification, it should be understood that the directional terms such as "upper" and "lower" used in the description of the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present invention. Furthermore, in the context, it should also be understood that when it is mentioned that one element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0024] This invention provides a method for preparing an electroactive material, comprising: A pore-forming agent, iron salt, and manganese salt are dissolved in a sugar solution to initiate a hydrothermal reaction, yielding a hydrothermal product. The hydrothermal products were carbonized at high temperature in an oxygen-free environment to obtain an iron-manganese-carbon electroactive material.

[0025] In this embodiment, iron from the iron salt, manganese from the manganese salt, and carbon from the sugar solution solute are sequentially subjected to hydrothermal reaction and high-temperature carbonization to obtain an iron-manganese-carbon electroactive material with a core-shell structure. Iron and manganese form the core, and carbon forms the shell. A pore-forming agent makes the resulting particulate material porous. The iron in the core structure is mainly in the form of iron carbide, ensuring the stability of the iron-carbon substrate. The introduction of manganese enhances the capacitive properties and supplements the manganese autotrophic denitrification process. It should also be noted that the manganese in the core-shell structure has a slow-release effect; the slow-release manganese is derived from Mn... 2+ To Mn 3+ The conversion, a process of oxidation, allows iron-manganese-carbon active materials to maintain good electrochemical stability and capacitance characteristics while also being able to withstand trace amounts of Mn. 2+ It releases available inorganic electron donors, promoting the denitrification process.

[0026] In this embodiment, the stable decontamination of the electroactive material at low temperatures is due to three aspects: firstly, enhanced electron transfer, where microorganisms utilize conductive interfaces for extracellular and interspecies electron transfer, accelerating the coupling of nitrification and denitrification processes; secondly, regulation of the microenvironment, promoting biofilm adhesion, alleviating the inhibition of denitrification by increased DO under low-temperature conditions, and simultaneously supplementing autotrophic denitrification with slowly released manganese ions; and thirdly, enrichment of microorganisms and genes, promoting the enrichment of nitrifying and denitrifying bacteria on the carrier, and enhancing electron transfer genes and quorum sensing genes.

[0027] It should be noted that many related technologies for iron and manganese use their autotrophic denitrification process as sacrificial materials. However, this application utilizes a variety of microorganisms, including nitrifying bacteria, denitrifying bacteria, and electroactive bacteria, to cross-link electrons at the material's conductive interface in an alternating anaerobic and aerobic environment, thereby enhancing the coupling of nitrification and denitrification. At the same time, the slow-release manganese supplements the manganese autotrophic denitrification, resulting in better nitrogen and phosphorus removal effects.

[0028] Iron-manganese-carbon electroactive materials are conducive to the enrichment of functional microorganisms related to nitrogen and phosphorus conversion, activate extracellular electron transport and quorum sensing pathways, drive efficient pollutant conversion and synergistic remodeling of microbial functional structure, and have good functional toughness and synergistic pollutant removal capabilities.

[0029] In summary, the electroactive material-enhanced mud-film synergistic system constructed in this invention overcomes the bottleneck problems of microbial destabilization and metabolic restriction under traditional low-temperature conditions, and provides a novel construction mode and control strategy for achieving efficient and stable low-temperature simultaneous nitrogen and phosphorus removal.

[0030] In some embodiments of the present invention, the pore-forming agent includes urea, the iron salt includes ferric chloride, the manganese salt includes manganese chloride, and the sugar solution includes an aqueous glucose solution.

[0031] The iron and manganese sources used in the iron-manganese-carbon material of the present invention can also be Fe(NO3)3 and MnSO4, or can be replaced by the following raw materials: iron-containing minerals (such as hematite, pyrite, limonite, steel slag, etc.), manganese-containing minerals (such as rhodochrosite, pyrolusite, manganese sand, etc.), and iron / manganese-containing waste resources (such as steelmaking waste slag, battery waste, manganese ore washing sludge, etc.).

[0032] In some embodiments of the present invention, the amount of solute added to the pore-forming agent and the sugar solution is 120~180g / L, the C:Fe molar ratio of sugar in the sugar solution to iron in the iron salt is (10~20):1, and the Fe:Mn molar ratio of iron salt to manganese salt is (1~3):1. The hydrothermal reaction is carried out at a temperature of 180-200℃ for 12-14 hours.

[0033] In some embodiments of the present invention, the process parameters for high-temperature carbonization include: a heating rate of 5~10℃ / min, a carbonization temperature of 800~900℃, and a carbonization time of 0.5~1 h.

[0034] In some embodiments of the present invention, after obtaining the iron-manganese-carbon electroactive material, the method further includes: The obtained iron-manganese-carbon electroactive material was loaded onto a sponge.

[0035] In this embodiment, the electroactive carrier has excellent pore structure, high specific surface area and hydrophilicity, which can promote the attachment and growth of microorganisms on its surface, improve the sludge stability and biomass retention capacity of the system under low temperature conditions, and construct a sludge-biofilm two-phase synergistic structure.

[0036] In some embodiments of the present invention, the sponge is a polyurethane sponge, the loading agent is a water-soluble polyurethane solution, and the density of the sponge is 30~35 kg / m³. 3 .

[0037] This invention also provides an electroactive material prepared according to any of the preparation methods described above.

[0038] This invention also provides an application of an electroactive material, based on any of the above-mentioned electroactive materials, the application including: During the sludge acclimatization stage, the reactor was initially continuously aerated, and then the aeration was adjusted to intermittent aeration to enhance the system's simultaneous nitrification and denitrification capabilities. During the normal temperature operation phase, the electroactive material is introduced into the reactor, and the aeration is changed to a continuous repeating pre-anaerobic + intermittent aeration mode to establish a sludge-biofilm synergistic system. During the low-temperature operation phase, when the temperature drops to 12~17℃, the aeration frequency of the intermittent aeration section in the aeration mode is increased.

[0039] By regulating the spatiotemporal conditions of pre-anaerobic and intermittent aeration, in the pre-anaerobic stage, denitrifying bacteria and polyphosphate-accumulating bacteria enhanced by electroactive carriers are enriched to achieve the removal of residual nitrate nitrogen and release of phosphorus. In the intermittent aeration stage, the electroactive carriers regulate electron transfer and dissolved oxygen (DO) to create a microenvironment conducive to simultaneous nitrification and denitrification as well as excessive phosphorus uptake by polyphosphate-accumulating bacteria, thus achieving stable nitrogen and phosphorus removal performance of the system under ambient to low temperature conditions.

[0040] In some embodiments of the present invention, the sludge acclimatization stage includes 27 days, with continuous aeration for the first 8 days and a 10-minute aeration / 10-minute rest period starting from the 9th day. The ambient temperature operation phase includes days 28 to 83, and the aeration mode includes 0.5 to 1 h of pre-anaerobic treatment + 4 to 5 h of intermittent aeration. The frequency of intermittent aeration is 10 min aeration / 10 min rest. The low-temperature operation phase includes days 84 to 105, and the aeration mode includes 0.5 to 1 h of pre-anaerobic treatment + 4 to 5 h of intermittent aeration. The frequency of intermittent aeration is 25 to 35 seconds of aeration / 40 to 50 seconds of rest. The aeration rate of the reactor is controlled within the range of 40~100 mL / min to maintain the dissolved oxygen concentration of the system between 0.3~1.0 mg / L.

[0041] In some embodiments of the present invention, the filling volume of the electroactive material is 20-40% of the reactor cavity volume.

[0042] To more clearly illustrate the technical solution and advantages of the present invention, the preparation method of an electroactive material is described in detail below through several embodiments.

[0043] Example 1: In this embodiment, urea, ferric chloride hexahydrate, manganese chloride tetrahydrate and glucose were used as raw materials for material synthesis. Iron-manganese-carbon powder material and iron-manganese-carbon electroactive carrier were prepared according to the preparation method involved in this invention, which have good pore structure and hydrophilicity.

[0044] 1) Weigh 22.5 g of urea, 13.5 g of ferric chloride hexahydrate and 4.95 g of manganese chloride tetrahydrate and dissolve them in 150 mL of glucose solution with a concentration of 150 g / L. The molar ratio of C:Fe is 15:1 and the molar ratio of Fe:Mn is 2:1. 2) Place the solution in a reaction vessel with a polytetrafluoroethylene liner and perform a hydrothermal reaction at 200°C for 14 hours, then allow it to cool naturally. 3) The solid-liquid mixture after the reaction was washed twice with pure water, twice with 75% ethanol, and once with pure water. Each wash was centrifuged at 6000 rpm for 3 min. The supernatant was discarded. After washing, the mixture was placed in a vacuum drying oven and dried under vacuum at 80℃ for 10 h to obtain a black powder. 4) Place the obtained black powder in a porcelain boat, heat it to 800℃ in a tube furnace at a heating rate of 10℃ / min, and hold it at 800℃ for 30 min. 5) Grind the carbonized material through a 100-mesh sieve to obtain iron-manganese-carbon powder; 6) Select a weight of 30-35 kg / m 3 To ensure that the polyurethane foam has similar physical properties, an iron-manganese-carbon electroactive carrier was prepared by using an aqueous polyurethane solution as a binder and mixing, extruding, and manually loading the iron-manganese-carbon powder material.

[0045] 7) The iron-manganese-carbon material is composed of Fe3C, Fe, MnO, and graphite, with a specific surface area of ​​114.9 m². 2 / g, pore volume is 0.140m³ 3 The sample, at / g, possesses both microporous and mesoporous structures, with a contact angle of 21.4°, exhibiting good hydrophilicity, which is beneficial for microbial attachment. The zeta potential in aqueous solution is -19.20 ± 0.20 mV.

[0046] Comparative Example 1: This embodiment differs from Example 1 in that manganese chloride tetrahydrate is not added during the material synthesis process. Everything else is the same as in Example 1, yielding iron-carbon powder and an iron-carbon electroactive carrier. The iron-carbon material is composed of Fe3C, Fe, and graphite, with a specific surface area of ​​60.2 m². 2 / g, pore volume is 0.082 m 3 / g, possessing microporous and mesoporous structures, with a contact angle of 83.3°. The zeta potential in aqueous solution is -21.88±2.22 mV.

[0047] Performance testing: To evaluate the electrochemical behavior and electron transfer capabilities of the iron-manganese-carbon materials and iron-carbon materials described in this invention, their performance was systematically characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Figure 2 The electrochemical performance of this embodiment and its comparative example (iron-carbon material) is shown.

[0048] 1) Cyclic voltammetry (CV) tests were performed at different scan rates within a potential range of -0.8 V to +0.8 V. Simultaneously, tests were conducted at frequencies ranging from 10... -2 Hz to 10 5 Electrochemical impedance spectroscopy (EIS) was performed in the Hz range to evaluate charge transfer resistance and diffusion behavior.

[0049] 2) Both iron-manganese-carbon (FeMC) and iron-carbon exhibit stable and reversible redox curves, demonstrating good electrochemical stability. FeMC exhibits an additional reduction peak compared to iron-carbon, indicating that manganese incorporation introduces additional redox active sites. The CV curve area of ​​FeMC is larger than that of iron-carbon, suggesting higher charge storage capacity and enhanced electron buffering behavior.

[0050] 2) Based on the linear fitting of log(peak current)-log(scan rate), the slope b values ​​of the iron-manganese-carbon materials were calculated to be 0.755, 0.806 and 0.819, respectively, which are close to 1. The b values ​​of the iron-carbon materials were 0.703 and 0.746, indicating that the charge storage behavior of the iron-manganese-carbon materials is mainly controlled by capacitance, and they have fast surface reaction and stronger direct electron transfer efficiency.

[0051] 3) Based on the Randles-Sevcik equation, the diffusion coefficient was calculated by the linear relationship between the square root of the scan rate and the peak current. The slope of the iron-manganese-carbon material was higher than that of the iron-carbon material, indicating that its ion diffusion ability was better.

[0052] 4) EIS test results show that the charge transfer resistance of the iron-manganese-carbon material is 8.56Ω and the Warburg coefficient is 1.30×10⁻⁶. -3 S·s 0.5 The charge transfer resistance is 18.87 Ω, and the Warburg coefficient is 4.64 × 10⁻⁶. -4 S·s 0.5 .

[0053] In summary, both iron-carbon and iron-manganese-carbon exhibit excellent electrochemical properties, including stable redox activity, capacitance-dominated characteristics, low interfacial resistance, and efficient ion diffusion. Iron-manganese-carbon outperforms iron-carbon in these indicators, suggesting stronger electron storage capacity and greater potential to promote microbial electron transfer, laying the electrochemical foundation for subsequent nitrogen-phosphorus conversion.

[0054] Application Example 1: To verify the denitrification and phosphorus removal performance and temperature adaptability of the low-temperature simultaneous denitrification and phosphorus removal mud-membrane synergistic system and its construction method based on electroactive carrier enhancement described in this invention during actual operation, electroactive carriers modified with iron-manganese-carbon materials were filled into the reactor to construct a mud-membrane symbiotic environment. Multiple stages of continuous operation tests were conducted, with the iron-carbon electroactive carrier group and the ordinary polyurethane sponge carrier group used as comparisons. A schematic diagram of the reactor is shown below. Figure 1 As shown, the reactor includes an influent substrate (1), an influent pump (2), a stirring system (3), a pH and DO testing system (4), an effluent pump (5), a gas flow meter (6), an aeration pump (7), a microporous aeration disc (8), an electroactive carrier (9), and a time control system (10). The effective working volume of the reactor is 1.5 L, the volume exchange rate is 56.7%, the hydraulic retention time is 0.44 d, the influent ammonia nitrogen concentration is set to 60 mg / L, and the initial COD / N ratio is 5.

[0055] 1) First stage: Sludge acclimatization period (days 1–27) Each reactor group was inoculated with activated sludge and started up, initially using continuous aeration. During the first 8 days of operation, all three systems showed high ammonia nitrogen removal rates (no residue in the effluent), but the nitrate nitrogen concentration was high, indicating that nitrification had been established, but the simultaneous denitrification effect was poor. To improve SND performance, from the 9th day onwards, the aeration mode was uniformly adjusted to "10 minutes of aeration / 10 minutes of rest".

[0056] 2) Second stage: Normal temperature operation period (days 28–83) The aeration strategy was further optimized to a "0.5 h pre-anaerobic + 4.5 h intermittent aeration" operation to create an alternating anaerobic-aerobic environment, establishing conditions conducive to EBPR, and three types of sponge carriers were added to construct a sludge-biofilm synergistic system. On day 64, the COD / N ratio was gradually increased from 5 to 7.5 to enhance the simultaneous denitrification process and reduce the effluent nitrate nitrogen and total nitrogen concentrations.

[0057] 3) Third stage: Low temperature operation period (days 84-105) The operating temperature was lowered from 25℃ to 15℃. Due to the reduced microbial activity caused by the low temperature, the system DO concentration increased. In order to avoid the potential inhibitory effect of excessive dissolved oxygen on the denitrification process, the intermittent aeration strategy was adjusted from the "10-minute aeration / 10-minute rest" cycle mode to a more frequent "30-second aeration / 45-second rest" cycle mode, thereby maintaining a more suitable DO level.

[0058] 4) The nitrogen and phosphorus concentrations in the effluent from the iron-manganese-carbon electroactive carrier group at 25℃ were 9.3 mg / L and 0.01 mg / L, respectively, with a nitrogen removal efficiency of 82.8%. At 15℃, the nitrogen and phosphorus concentrations in the effluent were 12.4 mg / L and 0.02 mg / L, respectively, with a nitrogen removal efficiency of 77.0%.

[0059] Application Comparative Example 1: This embodiment differs from Application Example 1 in that it uses an iron-carbon electroactive carrier as the functional carrier. Everything else is the same as in Application Example 1. At 25°C, the effluent nitrogen and phosphorus concentrations of the iron-carbon electroactive carrier are 11.8 mg / L and 0.01 mg / L, respectively, with a nitrogen removal efficiency of 78.1%. At 15°C, the effluent nitrogen and phosphorus concentrations are 13.1 mg / L and 0 mg / L, respectively, with a nitrogen removal efficiency of 73.6%.

[0060] Application Comparative Example 2: This embodiment differs from Application Example 1 in that it uses a common polyurethane foam carrier as the functional carrier. Otherwise, it is the same as the Application Example. At 25°C, the nitrogen and phosphorus concentrations in the effluent using the common polyurethane foam carrier are 12.6 mg / L and 0 mg / L, respectively, with a nitrogen removal efficiency of 76.7%. At 15°C, the nitrogen and phosphorus concentrations in the effluent are 16.1 mg / L and 0 mg / L, respectively, with a nitrogen removal efficiency of 70.0%.

[0061] The results in summary indicate that the mud-film synergistic system enhanced by the iron-manganese-carbon electroactive carrier exhibits stronger nitrogen removal performance, especially demonstrating greater stability and reaction coordination under low-temperature conditions. As the temperature decreases, the microbial activity of both the iron-carbon electroactive carrier and the conventional carrier group is significantly inhibited, leading to a decrease in the nitrification rate within the system. This results in a continuous increase in DO concentration under the original aeration settings, disrupting the microaerobic environment required for simultaneous nitrification and denitrification (e.g., ...). Figure 3 (As shown). Changes in dissolved oxygen (DO) reflect the dynamic balance between aeration input and microbial oxygen consumption. An abnormally high DO level indicates a lack of system regulation capacity. In contrast, the DO of the iron-manganese-carbon electroactive carrier group remained within a relatively stable range, indicating that this carrier helps maintain the stability of the nitrification process under low-temperature conditions and mitigates the inhibition of functional microorganisms by temperature. Simultaneously, the system effluent showed lower nitrate nitrogen and total nitrogen concentrations, reflecting superior simultaneous nitrification and denitrification capabilities.

[0062] Performance testing: To further elucidate the mechanism of electroactive carrier enhancement, the electron transport system activity of flocculent sludge and carrier biofilm in three reactors was tested after operation at 15°C to evaluate the activity of the microbial respiratory electron transport chain. Figure 4 As shown, the iron-manganese-carbon electroactive carrier group exhibits the strongest electron transport system activity in both flocs and biofilms. Furthermore, due to the conductivity of the electroactive material framework, the electron transport system activity of the carrier biofilm is much higher than that of ordinary carriers, further demonstrating that electroactive carriers can enhance system electron transport and thus promote pollutant transformation.

[0063] Performance testing: To further explore the synergistic mechanism of the iron-manganese-carbon electroactive support, X-ray photoelectron spectroscopy was used to analyze the initial material and the support samples after reactor operation, revealing its redox behavior and electron donor function during long-term operation. The iron-manganese-carbon support retained the typical characteristic peaks of C, O, Fe, and Mn after use. Among these, Mn 2p spectrum analysis revealed Mn... 2+ The proportion decreased from 38.76% to 19.92%, while Mn 3+ The percentage increased from 43.02% to 65.68%, reflecting the sustained-release Mn in the carrier. 2+ To Mn 3+ The oxidation process of the transformation demonstrates that the iron-manganese-carbon electroactive carrier not only possesses good electrochemical stability and capacitance characteristics, but also can be converted by trace amounts of Mn. 2+ It releases available inorganic electron donors, promoting the denitrification process.

[0064] Performance testing: To evaluate the biomass retention capacity and sludge stability of the sludge-film synergistic system under low-temperature conditions, the volatile suspended solids (VSS) concentration of suspended sludge in the three systems was measured at the end of the second stage (25℃) and the end of the third stage (15℃). In the sludge-film synergistic system constructed with an iron-manganese-carbon electroactive carrier, the sludge VSS concentration was 1.98 g / L at 25℃ and 1.80 g / L at 15℃, showing only a slight decrease, indicating that the system has good sludge retention capacity and low-temperature adaptability. The good adhesion interface and electron transport activity provided by the electroactive carrier supported the stability of the sludge film structure and effectively mitigated sludge loss caused by low temperature.

[0065] After using an iron-carbon electroactive carrier, the sludge VSS concentration of the system was 1.76 g / L at 25℃, and decreased to 0.80 g / L when the temperature was lowered to 15℃.

[0066] After using a conventional carrier, the VSS concentration in the system sludge was 1.18 g / L at 25°C, and further decreased to 0.40 g / L at 15°C. Based on the higher sludge biomass at both 25°C and 15°C, this indicates that the sludge film system constructed with the electroactive carrier helps to enhance system biomass retention and sludge stability.

[0067] Performance testing: To further verify the promoting effect of electroactive carriers on microbial attachment and structural stability under low temperature conditions, the formation characteristics of biofilm, distribution of extracellular polymers (EPS), and sludge structural response in the ordinary carrier group, iron-carbon electroactive carrier group, and iron-manganese-carbon electroactive carrier group were compared and analyzed.

[0068] like Figure 5As shown, the surface color of ordinary sponge carriers changed from white to light yellow, forming only a small amount of thin film-like biofilm. In contrast, the surface of the iron-manganese-carbon electroactive carrier formed a dense biofilm structure. Scanning electron microscopy images showed that the carrier framework was enriched with microorganisms and EPS secretions, superior to the ordinary carrier group and the iron-carbon electroactive carrier group. Further analysis of EPS content changes revealed that low-temperature stimulation generally induced microorganisms to increase EPS secretion to cope with environmental stress. In the ordinary carrier group, floc EPS increased from 281.3 mg / g VSS to 777.8 mg / g VSS, accompanied by a decrease in VSS concentration, reflecting a loose floc structure, deteriorated sedimentation, and a risk of biomass loss. In the iron-manganese-carbon electroactive carrier group, floc EPS remained stable, while EPS within the carrier increased, further enhancing biofilm formation on the carrier.

[0069] In summary, the electroactive carrier achieves dual enhancement of structural stability and functional bacterial enrichment by regulating microbial attachment behavior and extracellular polymer distribution, thus providing support for the efficient and stable operation of the system under low-temperature conditions.

[0070] Genetic testing: This embodiment reveals the enhanced effect of electroactive carriers on the enrichment of key functional bacteria, electron transport genes, and quorum sensing signal regulation under low temperature stress by conducting multi-omics analysis of the mud-film synergistic system under different carrier conditions. It also verifies the microbial response mechanism of the proposed "low temperature mud-film synergistic denitrification and phosphorus removal system driven by electroactive carriers".

[0071] 1) 16S rRNA sequencing results showed that the iron-manganese carbon electroactive carrier promoted nitrification by bacteria (such as...). Nitrospira and Nitrosoarchaeum ), denitrifying bacteria (such as Pseudomonas , Denitratisoma and Lentimicrobium ) and polyphosphate-accumulating bacteria (such as Dechloromonas The enrichment of key functional microorganisms such as bacteria in the carrier biofilm simultaneously inhibits the loss of microbial communities caused by low temperatures, enhancing the system's temperature tolerance and functional stability. Correspondingly, Chloroflexota Higher abundance on the carrier surface contributes to the construction of the biomembrane framework and the stability of EPS.

[0072] 2) Metagenomic analysis revealed that electroactive carriers promote extracellular electron transport (e.g., cymA , mtrA / B , omcS , eetA / B , fdhB , petA , nuoA ) and swarm sensing (e.g.) LuxR / Q / I / S , RpfC / F / G and LsrD / K The increased abundance of related genes promotes communication and synergistic metabolism among microorganisms.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an electroactive material, characterized in that, include: A pore-forming agent, iron salt, and manganese salt are dissolved in a sugar solution to initiate a hydrothermal reaction, yielding a hydrothermal product. The hydrothermal products were carbonized at high temperature in an oxygen-free environment to obtain an iron-manganese-carbon electroactive material.

2. The preparation method according to claim 1, characterized in that, The pore-forming agent includes urea, the iron salt includes ferric chloride, the manganese salt includes manganese chloride, and the sugar solution includes an aqueous glucose solution.

3. The preparation method according to claim 1, characterized in that, The amount of solute added to the pore-forming agent and sugar solution is 120~180g / L, the C:Fe molar ratio of sugar to iron in the sugar solution is (10~20):1, and the Fe:Mn molar ratio of iron salt to manganese salt is (1~3):

1. The hydrothermal reaction is carried out at a temperature of 180-200℃ for 12-14 hours.

4. The preparation method according to claim 1, characterized in that, The process parameters for high-temperature carbonization include: a heating rate of 5~10℃ / min, a carbonization temperature of 800~900℃, and a carbonization time of 0.5~1 h.

5. The preparation method according to claim 1, characterized in that, After obtaining the iron-manganese-carbon electroactive material, the process further includes: The obtained iron-manganese-carbon electroactive material was loaded onto a sponge.

6. The preparation method according to claim 5, characterized in that, The sponge is a polyurethane sponge, and the loading agent is a water-soluble polyurethane solution. The density of the sponge is 30~35 kg / m³. 3 .

7. An electroactive material, characterized in that, Prepared according to any one of the preparation methods described in claims 1-6.

8. An application of an electroactive material, characterized in that, Based on any one of the electroactive materials of claims 1-6, the applications include: During the sludge acclimatization stage, the reactor was initially continuously aerated, and then the aeration was adjusted to intermittent aeration to enhance the system's simultaneous nitrification and denitrification capabilities. During the normal temperature operation phase, the electroactive material is introduced into the reactor, and the aeration is changed to a continuous repeating pre-anaerobic + intermittent aeration mode to establish a sludge-biofilm synergistic system. During the low-temperature operation phase, when the temperature drops to 12~17℃, the aeration frequency of the intermittent aeration section in the aeration mode is increased.

9. The application according to claim 8, characterized in that, The sludge acclimatization phase lasts for 27 days. The first 8 days are in continuous aeration mode, and from the 9th day onwards, the aeration mode is adjusted to 10 minutes of aeration and 10 minutes of rest. The ambient temperature operation phase includes days 28 to 83, and the aeration mode includes 0.5 to 1 h of pre-anaerobic treatment + 4 to 5 h of intermittent aeration. The frequency of intermittent aeration is 10 min aeration / 10 min rest. The low-temperature operation phase includes days 84 to 105, and the aeration mode includes 0.5 to 1 h of pre-anaerobic treatment + 4 to 5 h of intermittent aeration. The frequency of intermittent aeration is 25 to 35 seconds of aeration / 40 to 50 seconds of rest. The aeration rate of the reactor is controlled within the range of 40~100 mL / min to maintain the dissolved oxygen concentration of the system between 0.3~1.0 mg / L.

10. The application according to claim 8, characterized in that, The filling volume of the electroactive material is 20-40% of the reactor cavity volume.

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