A composite ecological device for in-situ enhanced denitrification of low-temperature river water body and application thereof

Abstract

This invention relates to a composite ecological device for in-situ enhanced denitrification of low-temperature river water and its application. The composite ecological device for in-situ enhanced denitrification of low-temperature river water comprises, from top to bottom, an insulation layer, a nitrification layer, and a denitrification layer. The nitrification layer includes a biological blanket and composite biological packing material fixed on the biological blanket, with low-temperature resistant nitrifying bacteria inoculated on the biological blanket and composite biological packing material. The denitrification layer includes packing balls, which are doped with a slow-release carbon source and inoculated with low-temperature resistant denitrifying bacteria. This invention also provides an application of the composite ecological device for in-situ enhanced denitrification of low-temperature river water. This invention solves the problem of significantly reduced biological denitrification efficiency in traditional denitrification processes under low-temperature conditions, as well as the problems of poor connection between stratified treatments leading to retention of nitrification products, and insufficient alkalinity in the denitrification zone inhibiting denitrification. It also solves the problem of uncontrollable carbon source addition leading to secondary pollution.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a composite ecological device and its application for in-situ enhanced denitrification of low-temperature river water. Background Technology

[0002] When temperatures suddenly drop in winter, ammonia nitrogen and total nitrogen levels can rise sharply, primarily because nitrifying bacteria are highly sensitive to water temperature. These bacteria are responsible for converting nitrite into nitrate. When the water temperature falls below their optimal range, their activity decreases significantly, leading to a marked slowdown in ammonia nitrogen degradation. In addition, lower water temperatures in winter also reduce microbial activity, slowing the decomposition of organic matter, which also contributes to increased ammonia nitrogen and total nitrogen levels.

[0003] However, most existing low-temperature water treatment devices are designed for the treatment of domestic sewage and industrial wastewater. Their frame structure is relatively compact and complex, usually a tank structure. Most existing equipment is a stationary sewage treatment plant facility and requires power facilities, such as heating layers and aeration devices. As a result, they cannot be directly applied to flowing natural water bodies and lack insulation design.

[0004] Meanwhile, traditional denitrification processes have the following shortcomings when used in low-temperature natural water bodies: 1) For example, the A / O process relies on microbial activity. When the water temperature is below 15℃, the activity of nitrifying / denitrifying bacteria will decrease sharply, with the nitrification rate decreasing by 50% to 70% from its original level. Microbial enzyme activity will also be inhibited; for example, the activity of nitrite oxidase at 10℃ is only 30% of that at 25℃. 2) Liquid carbon sources (such as methanol and sodium acetate) can easily cause instantaneous excess, leading to COD fluctuations exceeding 50%. An imbalance in the carbon-to-nitrogen ratio (C / N) can easily trigger the release of N2O greenhouse gases, with release amounts potentially 3 to 5 times higher than normal. 3) River environments have a high heat loss rate; without insulation measures, the heat utilization rate of the nitrification reaction is less than 20%. Diurnal temperature variations cause fluctuations in microbial metabolism; when the temperature fluctuation is ±5℃, the denitrification stability will decrease by 40% from its original level. 4) Nitrification products (NO... 3- The nitrogen removal process is hampered by several factors: failure to transfer nitrogen to the denitrification zone in a timely manner, resulting in a retention rate >30%; and insufficient alkalinity in the denitrification zone, which inhibits the nitrogen removal process. For example, denitrifying enzymes will be inactivated when the pH value is below 6.5. Therefore, there is an urgent need to find an in-situ enhanced nitrogen removal device suitable for low-temperature river water bodies. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a composite ecological device and application for in-situ enhanced denitrification of low-temperature river water, so as to solve the problem that the efficiency of biological denitrification of traditional denitrification processes is significantly reduced in low-temperature environments. It can also solve the problems of poor connection between stratified treatment, resulting in the retention of nitrification products, and insufficient alkalinity in the denitrification zone inhibiting denitrification. Furthermore, it can solve the problems of uncontrollable carbon source addition leading to secondary pollution and the difficulty in maintaining the thermal energy of open water bodies.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A composite ecological device for in-situ enhanced denitrification in low-temperature river water consists of an insulation layer, a nitrification layer, and a denitrification layer arranged sequentially from top to bottom.

[0008] The nitrification layer includes a bio-mat and a composite biological packing material fixed on the bio-mat, and the bio-mat and the composite biological packing material are inoculated with low-temperature nitrifying bacteria.

[0009] The denitrification layer includes packing balls, which are doped with a slow-release carbon source and inoculated with low-temperature resistant denitrifying bacteria.

[0010] Based on the aforementioned technical methods, by sequentially setting up an insulation layer, a nitrification layer, and a denitrification layer from top to bottom, in-situ efficient nitrogen removal in low-temperature river water is achieved. The insulation layer effectively reduces heat loss, maintains temperature stability in the nitrification and denitrification layers, and provides a suitable living environment for microorganisms. The biofilm and composite biological packing material in the nitrification layer provide abundant attachment surfaces for low-temperature resistant nitrifying bacteria, enabling them to efficiently oxidize ammonia nitrogen to nitrate. Meanwhile, the packing balls in the denitrification layer, doped with slow-release carbon sources, provide energy for low-temperature resistant denitrifying bacteria, promoting their reduction of nitrate to nitrogen gas. Furthermore, placing the nitrification layer above the denitrification layer allows the heat generated by the nitrification reaction to further provide energy for the denitrifying bacteria, further promoting the reduction of nitrate to nitrogen gas. This layered design forms a complete denitrification chain, which not only solves the problem of the significant decrease in biological denitrification efficiency in traditional denitrification processes under low-temperature conditions, but also solves the problem of poor connection between layered treatments leading to the retention of nitrification products. At the same time, by adding slow-release carbon sources, it avoids the problem of insufficient alkalinity in the denitrification zone inhibiting denitrification, significantly improving denitrification efficiency, and also effectively solves the problem of difficulty in maintaining thermal energy in open water bodies.

[0011] Preferably, the insulation layer comprises an upper light-transmitting insulation cover film and a lower insulation material layer.

[0012] Preferably, the light-transmitting and heat-insulating cover film is selected from at least one of a dimming film, a photothermal conversion film, and a self-cleaning ETFE film.

[0013] Preferably, the material of the insulation layer is selected from at least one of polyurethane foam insulation material, aerogel felt and phase change energy storage material.

[0014] Preferably, the light transmittance of the dimming film is ≥85%. The dimming film is an electronically controlled light-controlling thin film material made using PDLC (polymer dispersed liquid crystal) technology. Its core characteristic is that it can be transparent when energized, and become a translucent but opaque hazy state when de-energized, thus combining privacy protection and light adjustment functions.

[0015] By selecting a light-transmitting film with a light transmittance of ≥85% as the upper material of the insulation layer, not only can sunlight be efficiently transmitted, ensuring that the lower insulation material fully absorbs light energy and heats up, but it can also effectively play a role in heat insulation and protection of the lower insulation material, significantly reducing its cooling rate.

[0016] Preferably, the thermal conductivity of the polyurethane foam insulation material layer is ≤0.025 W / m·K. This allows for the use of light to raise the temperature of the underlying nitration and denitration layers.

[0017] By selecting polyurethane foam insulation material with a thermal conductivity of ≤0.025 W / m·K, heat transfer is effectively prevented and heat loss is reduced, thereby ensuring the water temperature of the nitrification and denitrification layers.

[0018] Preferably, the composite biological packing material of the nitrification layer includes composite biological packing balls and biological ropes connecting the composite biological packing balls;

[0019] The composite biofiller balls are selected from composite filler balls of volcanic rock and zeolite and / or graphene-modified ceramsite, and the specific surface area of ​​the composite filler balls of volcanic rock and zeolite is ≥500 m². 2 / m 3 .

[0020] By selecting a specific surface area ≥500 m² 2 / m 3 The composite packing balls made of volcanic rock and zeolite not only ensure the enrichment of low-temperature nitrifying bacteria but also enhance mass transfer efficiency. The high specific surface area provides more attachment sites for microorganisms, and its microporous structure creates a capillary effect, promoting the diffusion rate of dissolved oxygen and ammonia nitrogen. Simultaneously, it buffers pH fluctuations; the CaO (approximately 5-8%) in the volcanic rock and the aluminosilicate structure of the zeolite neutralize the H₂ produced during nitrification. + .

[0021] Preferably, the bio-rope is made of polylactic acid (PLA) woven mesh.

[0022] Among them, the composite biological filler balls are fixed on the biological blanket after being connected in series by biological ropes.

[0023] Preferably, the preparation method of the graphene-modified ceramsite includes the following steps:

[0024] After acid washing, graphene is grown on the surface of shale ceramic particles by chemical vapor deposition (CVD) at a temperature of 800℃, with 3 to 5 graphene layers.

[0025] Preferably, the composition of the shale ceramsite, by mass percentage, includes 45-50% aluminum oxide (Al2O3) and 30-35% silicon dioxide (SiO2), with the remainder being ceramsite.

[0026] Preferably, the pickling is performed by soaking in a 5% nitric acid (HNO3) aqueous solution for 24 hours.

[0027] Preferably, the thickness of the graphene grown on the surface of the shale ceramsite is 1.2~2 nm.

[0028] Preferably, the packing balls of the denitrification layer are selected from composite packing balls of volcanic rock and zeolite and / or metal-organic frameworks (MOFs), wherein the mass ratio of volcanic rock to zeolite is 3:2, the particle size of the composite packing balls of volcanic rock and zeolite is 10~20mm, and the specific surface area is ≥500 m². 2 / m 3 .

[0029] By selecting particles with a diameter of 10~20mm and a specific surface area ≥500 m², 2 / m 3 The composite packing balls ensure the efficient enrichment of low-temperature resistant denitrifying bacteria.

[0030] Preferably, the metal-organic framework (MOF) material is selected from ZIF-8, and the specific surface area of ​​ZIF-8 is >1000 m². 2 / m 3 .

[0031] ZIF-8 (Zeolitic Imidazolate Framework-8) is a metal-organic framework (MOF) material with a unique structure and excellent properties, belonging to the zeolite-like imidazolate framework material category.

[0032] Preferably, the packing balls of the denitrification layer are doped with a composite of slow-release sulfur preparation and slow-release carbon source particles, wherein the C / N ratio of the slow-release carbon source is ≥6.

[0033] By doping the packing balls of the denitrification layer with a slow-release sulfur agent and a slow-release carbon source composite particle, the slow-release sulfur agent acts as an electron donor (S) under low-temperature conditions. 0 → SO4 2-This process, in synergy with a slow-release carbon source, provides a stable energy source for low-temperature-tolerant denitrifying bacteria. This synergistic effect ensures that the bacteria maintain high denitrifying enzyme activity under low-temperature conditions, thereby significantly improving the in-situ nitrogen removal efficiency under these conditions and further optimizing the overall nitrogen removal performance of the composite ecological device. It effectively solves the problem of uncontrollable carbon source addition leading to secondary pollution associated with traditional methods.

[0034] Preferably, the sustained-release sulfur preparation is selected from sulfur granules and / or sodium thiosulfate-palmitite sustained-release tablets.

[0035] Preferably, the slow-release carbon source is selected from lignin and / or polyhydroxyalkanoates (PHA).

[0036] The lignin degradation rate is 0.05-0.1 g / (L·d), avoiding the instantaneous excessive addition of traditional liquid carbon sources (such as methanol) and reducing the risk of carbon emissions. Sulfur oxidation provides electrons (S... 0 +6NO3 - →SO4 2- +3N2↑) forms a dual-pathway denitrification with lignin carbon source, thereby significantly improving the denitrification rate of low-temperature river water.

[0037] Preferably, the packing balls of the denitrification layer are suspended below the bio-mat using bio-ropes.

[0038] By suspending the packing balls of the denitrification layer directly below the biological blanket, the denitrification layer is placed directly below the nitrification layer, effectively ensuring the preservation of nitrification products (NO3). - The nitrogen is promptly transferred to the denitrification zone, greatly reducing the retention rate and further improving the nitrogen removal efficiency.

[0039] Preferably, the packing balls of the denitrification layer are also loaded with anthraquinone-2-sulfonate (AQS).

[0040] By loading anthraquinone-2-sulfonate (AQS) into the packing balls of the denitrification layer, AQS can act as an electron acceptor during denitrification, thereby improving electron transfer efficiency and accelerating nitrate (NO3) reduction. - The reduction of nitrogen (N2) to nitrogen gas improves denitrification efficiency. Experiments have shown that AQS can significantly increase the denitrification reaction rate and reduce the hydraulic retention time.

[0041] Preferably, the low-temperature nitrifying bacteria are selected from immobilized nitrifying bacteria microcapsules and / or magnetically responsive bacterial agents, and the low-temperature nitrifying bacteria are selected from (Arctic isolates) and / or cold-resistant Acinetobacter, etc.

[0042] Preferably, the low-temperature resistant denitrifying bacteria are selected from at least one of Pseudomonas schrenckii, Thiobacillus, and Bacillus.

[0043] Preferably, the biofilm blanket is selected from at least one of polyurethane biofilm blanket, polyethylene biofilm blanket, and polypropylene biofilm blanket.

[0044] The present invention also provides a composite ecological device for in-situ enhanced denitrification of low-temperature river water as described in the present invention, which is used for in-situ denitrification of low-temperature river water, wherein the temperature of the low-temperature river water is 5~10℃.

[0045] Preferably, the composite ecological device achieves an in-situ denitrification efficiency of over 50% for low-temperature river water. In contrast, existing denitrification devices typically have a denitrification efficiency of around 30%.

[0046] The beneficial effects of this invention are:

[0047] This invention relates to a composite ecological device for in-situ enhanced nitrogen removal in low-temperature river water. By sequentially configuring an insulation layer, a nitrification layer, and a denitrification layer from top to bottom, it achieves highly efficient in-situ nitrogen removal in low-temperature river water. The insulation layer effectively reduces heat loss, maintaining temperature stability in both the nitrification and denitrification layers and providing a suitable living environment for microorganisms. The biofilm and composite biological packing material in the nitrification layer provide abundant attachment surfaces for low-temperature resistant nitrifying bacteria, enabling them to efficiently oxidize ammonia nitrogen to nitrate. Meanwhile, the packing balls in the denitrification layer, doped with a slow-release carbon source, provide energy for low-temperature resistant denitrifying bacteria, promoting the reduction of nitrate to nitrogen gas. Furthermore, placing the nitrification layer above the denitrification layer allows the heat generated by the exothermic nitrification reaction to further provide energy for the denitrifying bacteria, further promoting the reduction of nitrate to nitrogen gas. This layered design forms a complete denitrification chain, which not only solves the problem of significantly reduced biological denitrification efficiency in traditional denitrification processes at low temperatures, but also addresses the issue of poor integration between layered treatments leading to nitrification product retention. Furthermore, the addition of a slow-release carbon source avoids the problem of insufficient alkalinity in the denitrification zone inhibiting denitrification, significantly improving denitrification efficiency. It also effectively solves the problem of maintaining thermal energy in open water bodies. In addition, the device has a simple structure, is easy to install and maintain, and is suitable for application in natural water bodies such as rivers and lakes. Its eco-friendly characteristics, without the introduction of chemical agents, meet environmental protection requirements and have significant environmental and economic benefits, making it worthy of widespread application in the field of low-temperature river water remediation technology. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the composite ecological device.

[0049] Figure 2 This is a picture of a composite biological filler ball.

[0050] Figure 3 A physical image of a composite ecological device placed in a low-temperature river body for in-situ enhanced denitrification;

[0051] Among them, 1-insulation layer; 2-nitrification layer; 21-biological blanket; 22-composite biological packing ball; 23-biological rope; 3-denitrification layer; 31-packing ball. Detailed Implementation

[0052] The following description, with reference to preferred embodiments, illustrates the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are merely illustrative of the present invention and not intended to limit the scope of protection of the present invention.

[0053] The purpose of this invention is to provide a composite ecological device and application for in-situ enhanced denitrification of low-temperature river water, in order to solve the problem that the efficiency of biological denitrification in traditional denitrification processes is significantly reduced in low-temperature environments. It can also solve the problems of poor connection between stratified treatment, resulting in the retention of nitrification products, and insufficient alkalinity in the denitrification zone inhibiting denitrification. Furthermore, it can solve the problems of uncontrollable carbon source addition leading to secondary pollution, and the difficulty in maintaining the thermal energy of open water bodies.

[0054] Among them, such as Figure 1 As shown, the composite ecological device for in-situ enhanced denitrification of low-temperature river water consists of an insulation layer 1, a nitrification layer 2, and a denitrification layer 3 arranged sequentially from top to bottom.

[0055] Nitrification layer 2 includes a bio-mat 21 and a composite biological packing material fixed on the bio-mat 21. The bio-mat 21 and the composite biological packing material are inoculated with low-temperature nitrifying bacteria.

[0056] The denitrification layer 3 includes packing balls 31, which are doped with slow-release carbon sources and inoculated with low-temperature resistant denitrifying bacteria.

[0057] By sequentially setting up an insulation layer, a nitrification layer, and a denitrification layer from top to bottom, in-situ and highly efficient nitrogen removal in low-temperature river water is achieved. The insulation layer effectively reduces heat loss, maintains temperature stability in the nitrification and denitrification layers, and provides a suitable living environment for microorganisms. The biofilm and composite biological packing material in the nitrification layer provide abundant attachment surfaces for low-temperature resistant nitrifying bacteria, enabling them to efficiently oxidize ammonia nitrogen to nitrate. Meanwhile, the packing balls in the denitrification layer, doped with slow-release carbon sources, provide energy for low-temperature resistant denitrifying bacteria, promoting their reduction of nitrate to nitrogen gas. Furthermore, placing the nitrification layer above the denitrification layer allows the heat generated by the nitrification reaction to further provide energy for the denitrifying bacteria, further promoting the reduction of nitrate to nitrogen gas. This layered design forms a complete denitrification chain, which not only solves the problem of the significant decrease in biological denitrification efficiency in traditional denitrification processes under low-temperature conditions, but also solves the problem of poor connection between layered treatments leading to the retention of nitrification products. At the same time, by adding slow-release carbon sources, it avoids the problem of insufficient alkalinity in the denitrification zone inhibiting denitrification, significantly improving denitrification efficiency, and also effectively solves the problem of difficulty in maintaining thermal energy in open water bodies.

[0058] The nitrification reaction in the upper nitrification layer 2 is exothermic, releasing approximately 4.3 kcal per 1 g of NH3-N oxidized, thus providing a slow and continuous energy source for the low-temperature resistant denitrifying bacteria in the lower layer.

[0059] In some embodiments, in order to enable sunlight to penetrate efficiently, ensure that the lower insulation material fully absorbs light energy and heats up, and effectively protect the lower insulation material from heat loss, the insulation layer is configured to include an upper light-transmitting insulation cover film and a lower insulation material layer.

[0060] By cleverly designing a light-transmitting and heat-insulating cover film and a heat-insulating material layer to store solar heat energy, energy-free heat preservation is achieved. Tests have shown that after physical insulation using the light-transmitting and heat-insulating cover film and heat-insulating material layer, the temperature of nitrification layer 2 and denitrification layer 3 can be maintained at 8~12℃, while the optimal temperature for the low-temperature resistant bacterial agent is 8~15℃. This ensures that the low-temperature resistant bacterial agent maintains more than 70% of its enzyme activity, while the enzyme activity of traditional room-temperature bacteria at this temperature is <30%.

[0061] In some embodiments, the light-transmitting heat-insulating cover film is selected from at least one of a dimming film, a photothermal conversion film, and a self-cleaning ETFE film.

[0062] The photothermal conversion film contains a nano-indium tin oxide coating, which can further convert 30% of the light energy into heat energy. The self-cleaning ETFE film is coated with a titanium dioxide coating, resulting in a light transmittance attenuation rate of <5% / year.

[0063] In some embodiments, the material of the insulation layer is selected from at least one of polyurethane foam insulation material, aerogel felt and phase change energy storage material.

[0064] The thermal conductivity of the aerogel felt is ≤0.018 W / m·K. The phase change energy storage material is a paraffin / expanded graphite composite with a phase change temperature of 10~15℃.

[0065] In some embodiments, the light transmittance of the dimming film is ≥85%. The dimming film is an electronically controlled light-controlling thin film material made using PDLC (polymer dispersed liquid crystal) technology. Its core characteristic is that it can be transparent when energized and become a transparent but opaque hazy state when de-energized, thus combining privacy protection and light adjustment functions.

[0066] In some embodiments, to effectively prevent heat transfer and reduce heat loss, thereby ensuring the water temperature of the nitrification and denitrification layers, polyurethane foam insulation material with a thermal conductivity ≤0.025 W / m·K is selected as the insulation layer. This allows sunlight to be used to raise the temperature of the lower nitrification and denitrification layers.

[0067] In some embodiments, the composite biological packing material of the nitrification layer 2 includes composite biological packing material balls 22 and biological ropes 23 connecting the balls of the composite biological packing material 22.

[0068] Among them, such as Figure 2 As shown, the composite biological filler ball 22 is selected from composite filler balls of volcanic rock and zeolite and / or graphene-modified ceramsite, and the specific surface area of ​​the composite filler ball of volcanic rock and zeolite is ≥500 m². 2 / m 3 .

[0069] In some embodiments, the bio-rope 23 is made of polylactic acid (PLA) woven mesh. The composite bio-filler balls 22 are connected in series with the bio-rope 23 and fixed to the bio-mat 21. The PLA woven mesh is biodegradable and has a specific surface area 20% larger than that of ordinary bio-ropes.

[0070] In some embodiments, the preparation method of graphene-modified ceramic particles includes the following steps:

[0071] After acid washing, graphene is grown on the surface of shale ceramic particles by chemical vapor deposition (CVD) at a temperature of 800℃, with 3 to 5 graphene layers.

[0072] The shale ceramsite composition, by mass percentage, includes 45-50% aluminum oxide (Al₂O₃) and 30-35% silicon dioxide (SiO₂). Acid washing involves immersion in a 5% nitric acid (HNO₃) aqueous solution for 24 hours. The thickness of the graphene grown on the surface of the shale ceramsite is 1.2-2 nm.

[0073] Graphene-modified ceramsite gives it electrical conductivity, and tests have shown that this conductivity increases the activity of nitrifying bacteria by about 30%.

[0074] When graphene-modified ceramic particles are used as composite biological filler balls, the reaction mechanism is as follows: 1) Reconstruction of electron transport pathways:

[0075] The sp² hybrid orbitals of graphene form a continuous electron transport channel, which nitrifying bacteria (Nitrosomonas) use to transfer electrons generated from the oxidation of ammonia via cytochrome c (Cyt c). - Directly transferred to the conductive carrier:

[0076] NH3→ NH2OH → NO2 - (Release 4e) - )

[0077] The increased conductivity improves the electron transfer rate from 0.3 e in traditional carriers. - / s / cells increased to 1.2 e - / s / cell (4x increase).

[0078] 2) Regulation of biomembrane metabolism:

[0079] A micro-electric field (approximately 0.15 V / m) is formed on the surface of conductive ceramic particles, promoting the adjustment of the polysaccharide (PS) to protein (PN) ratio in EPS (extracellular polymeric substances) from 1:1.2 to 1:0.8, enhancing the mechanical strength of the biomembrane (shear resistance increased by 65%), and microcurrent stimulation increasing the activity of ammonia monooxygenase (AMO) from 0.8 U / mg to 1.2 U / mg (+50%). The metabolic kinetics are compared with those of conventional ceramic particles (ceramsite without any treatment or modification) in Table 1.

[0080] Table 1 shows the comparison of metabolic kinetics.

[0081] In some embodiments, the packing balls of the denitrification layer are selected from composite packing balls of volcanic rock and zeolite and / or metal-organic frameworks (MOFs), wherein the particle size of the composite packing balls of volcanic rock and zeolite is 10-20 mm and the specific surface area is ≥500 m². 2 / m 3 .

[0082] By selecting particles with a diameter of 10~20mm and a specific surface area ≥500 m², 2 / m 3 The composite packing balls ensure the efficient enrichment of low-temperature resistant denitrifying bacteria.

[0083] In some embodiments, the metal-organic framework (MOF) material is selected from ZIF-8, wherein the specific surface area of ​​ZIF-8 is >1000 m².2 / m 3 ZIF-8 (Zeolitic Imidazolate Framework-8) is a metal-organic framework (MOF) material with a unique structure and excellent properties, belonging to the zeolite-like imidazolate framework material category.

[0084] In some embodiments, the packing spheres 31 of the denitrification layer 3 are doped with a composite of slow-release sulfur preparation and slow-release carbon source, wherein the C / N ratio of the slow-release carbon source is ≥6. The slow-release sulfur preparation acts as an electron donor (SN) under low-temperature conditions. 0 →SO4 2- This process, in synergy with a slow-release carbon source, provides a stable energy source for low-temperature-tolerant denitrifying bacteria. This synergistic effect ensures that the bacteria maintain high denitrifying enzyme activity under low-temperature conditions, thereby significantly improving the in-situ nitrogen removal efficiency under these conditions and further optimizing the overall nitrogen removal performance of the composite ecological device. It effectively solves the problem of uncontrollable carbon source addition leading to secondary pollution associated with traditional methods.

[0085] In some embodiments, the packing balls 31 of the denitrification layer 3 are suspended below the bio-mat by bio-rope 23.

[0086] In some embodiments, the slow-release sulfur formulation is selected from sulfur granules and / or sodium thiosulfate-palmitite slow-release tablets. Experimental results show that using sulfur granules to replace traditional carbon sources (such as methanol) reduces CO2 emissions by 0.8 kg per ton of water treated. Furthermore, the slow-release period of both sulfur granules and sodium thiosulfate-palmitite slow-release tablets can be as long as 60 days.

[0087] In some embodiments, the slow-release carbon source is selected from lignin and / or polyhydroxyalkanoate (PHA) particles. The lignin degradation rate is 0.05-0.1 g / (L·d), avoiding the instantaneous excessive addition of traditional liquid carbon sources (such as methanol) and reducing the risk of carbon emissions. Sulfur oxidation provides electrons (S... 0 +6NO3 - →SO4 2- +3N2↑) forms a dual-pathway denitrification with lignin carbon source, thereby significantly improving the denitrification rate of low-temperature river water.

[0088] Among them, the C / N ratio of polyhydroxyalkanoate (PHA) particles is 8:1, and its biodegradation is controllable.

[0089] In some embodiments, the packing balls of the denitrification layer are also loaded with anthraquinone-2-sulfonate (AQS); by loading anthraquinone-2-sulfonate (AQS) into the packing balls of the denitrification layer, AQS can act as an electron acceptor during denitrification, thereby improving electron transfer efficiency and accelerating nitrate (NO3) precipitation. -The reduction of nitrogen (N2) to nitrogen gas improves denitrification efficiency. Experiments have shown that AQS can significantly increase the denitrification reaction rate and reduce the hydraulic retention time.

[0090] In some embodiments, the low-temperature nitrifying bacteria are selected from immobilized nitrifying bacteria microcapsules and / or magnetically responsive bacterial agents.

[0091] Among them, the carrier of the immobilized nitrifying bacteria microcapsules is a sodium alginate-attapulgite composite carrier, which can ensure that the survival rate of nitrifying bacteria is >80% at low temperatures.

[0092] Magnetic responsive bacterial agents, through the loading of bacterial cells with Fe3O4, can regulate the distribution of biofilm through a magnetic field.

[0093] Among them, the low-temperature nitrifying bacteria are selected from (Arctic isolates) and / or cold-resistant Acinetobacter, etc.

[0094] In some embodiments, the low-temperature resistant denitrifying bacteria are selected from at least one of Pseudomonas schrenckii, Thiobacillus, and Bacillus.

[0095] In some embodiments, the biofilm blanket is selected from at least one of polyurethane biofilm blanket, polyethylene biofilm blanket, and polypropylene biofilm blanket.

[0096] In some embodiments, a composite ecological device for in-situ enhanced denitrification of low-temperature river water is also provided for in-situ denitrification of low-temperature river water with a temperature of 5-10°C. The composite ecological device achieves an in-situ denitrification efficiency of over 50% for low-temperature river water.

[0097] To make the technical problems, solutions, and beneficial effects solved by this application clearer, the following will provide a more detailed description of the composite ecological device for in-situ enhanced nitrogen removal in low-temperature river water and its application, in conjunction with specific embodiments and accompanying drawings. Obviously, the described specific embodiments are merely some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the specific embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0098] Where specific techniques or conditions are not specified in the detailed embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0099] Example 1

[0100] A composite ecological device for in-situ enhanced denitrification in low-temperature river water is used as a method for in-situ enhanced denitrification in low-temperature river water, comprising the following steps:

[0101] S1. Preparation of a composite ecological device for in-situ enhanced denitrification in low-temperature river water: The composite ecological device consists of an insulation layer, a nitrification layer and a denitrification layer arranged from top to bottom.

[0102] The insulation layer consists of an upper light-transmitting film with a light transmittance of ≥85% and a lower polyurethane foam insulation material with a thermal conductivity of ≤0.025 W / m·K;

[0103] The nitrification layer includes a polyurethane biofilm blanket and graphene-modified ceramic pellets immobilized on the polyurethane biofilm blanket. Immobilized nitrifying bacteria microcapsules are inoculated on the polyurethane biofilm blanket and the graphene-modified ceramic pellets.

[0104] The graphene-modified ceramic pellets are fixed on the polyurethane biofilm blanket after being connected in series by a polylactic acid (PLA) woven mesh. Both the graphene-modified ceramic pellets and the polyurethane biofilm blanket are inoculated with nitrifying bacteria, which include at least Candida nitrosamine (Arctic isolate) and Acinetobacter pyrolyticus.

[0105] The preparation method of graphene-modified ceramic spheres is as follows: Shale ceramic spheres, comprising 50% alumina (Al2O3) and 35% silica (SiO2) by mass percentage, are soaked in a 5% nitric acid (HNO3) aqueous solution for 24 hours. Then, graphene is grown on the surface of the shale ceramic spheres by chemical vapor deposition (CVD) at a temperature of 800℃, with 5 graphene layers. The thickness of the graphene grown on the shale ceramic sphere surface is 2 nm.

[0106] The denitrification layer consists of particles with a diameter of 10-20 mm and a specific surface area ≥ 500 m². 2 / m 3 The composite packing balls, with a mass ratio of volcanic rock to zeolite of 3:2, are suspended on a polyurethane biofilm blanket by a polylactic acid (PLA) woven mesh. The composite packing balls are doped with sulfur particles and lignin slow-release carbon source (C / N≥6). The composite packing balls are inoculated with low-temperature resistant denitrifying bacteria, including at least Pseudomonas schistosomiasis, Thiobacillus, and Bacillus.

[0107] A schematic diagram of the structure of the composite ecological device is shown below. Figure 1 As shown;

[0108] S2, Filling with packing material: such as Figure 3 As shown, the composite ecological device prepared in S1 was placed in the farmland drainage area of ​​Rudong County, Nantong City, Jiangsu Province, where the continuous water body has low flow rate and a flow rate ≤ 1 m³ / s. 3 / s, in a low-temperature environment (around 5℃), the river water volume to be treated is 12 m wide × 20 m long × 1 m deep = 240 m³. 3 The same size composite ecological device was designed based on the river flow and channel dimensions. On day 1, the composite ecological device was placed in the river test area. Starting from day 2, water samples were taken daily at 5 PM from 300 m upstream of the device and directly below it for determination of total nitrogen, nitrate nitrogen, and ammonia nitrogen content. The experiment was monitored for a total of 8 days. The determination of total nitrogen, nitrate nitrogen, and ammonia nitrogen in the water samples was conducted by a third-party professional testing company. The results are shown in Table 2.

[0109] Table 2. Results of determination of total nitrogen, nitrate nitrogen and ammonia nitrogen

[0110] Table 2 shows the trends in total nitrogen, nitrate nitrogen, and ammonia nitrogen at the upstream location and the equipment, based on the obtained monitoring data. Before the equipment was deployed, the total nitrogen concentration in the experimental area was 1.49 mg / L. 48 hours after deployment, the total nitrogen concentration at the equipment location decreased to 1.15 mg / L, with a removal rate of approximately 23%. Over the seven-day experiment, the total nitrogen concentration in the experimental area showed a continuous and stable decline, with an overall removal efficiency of approximately 51%, and the total nitrogen concentration decreased from 1.49 mg / L to 0.73 mg / L.

[0111] In summary, the composite ecological device for in-situ enhanced nitrogen removal in low-temperature river water of the present invention achieves efficient in-situ nitrogen removal in low-temperature river water by sequentially setting up an insulation layer, a nitrification layer, and a denitrification layer from top to bottom. The insulation layer effectively reduces heat loss and maintains temperature stability in the nitrification and denitrification layers, providing a suitable living environment for microorganisms. The biofilm and composite biological packing material in the nitrification layer provide abundant attachment surfaces for low-temperature resistant nitrifying bacteria, enabling them to efficiently oxidize ammonia nitrogen to nitrate. Meanwhile, the packing balls in the denitrification layer, doped with slow-release carbon sources, provide energy for low-temperature resistant denitrifying bacteria, promoting their reduction of nitrate to nitrogen gas. Furthermore, placing the nitrification layer above the denitrification layer allows the heat generated by the exothermic nitrification reaction to further provide energy for the denitrifying bacteria, further promoting the reduction of nitrate to nitrogen gas. This layered design forms a complete denitrification chain, which not only solves the problem of significantly reduced biological denitrification efficiency in traditional denitrification processes at low temperatures, but also addresses the issue of poor integration between layered treatments leading to nitrification product retention. Furthermore, the addition of a slow-release carbon source avoids the problem of insufficient alkalinity in the denitrification zone inhibiting denitrification, significantly improving denitrification efficiency. It also effectively solves the problem of maintaining thermal energy in open water bodies. In addition, the device has a simple structure, is easy to install and maintain, and is suitable for application in natural water bodies such as rivers and lakes. Its eco-friendly characteristics, without the introduction of chemical agents, meet environmental protection requirements and have significant environmental and economic benefits, making it worthy of widespread application in the field of low-temperature river water remediation technology.

[0112] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A composite ecological device for in-situ enhanced denitrification of low-temperature river water, characterized in that, It consists of an insulation layer, a nitrification layer, and a denitrification layer arranged sequentially from top to bottom; The nitrification layer includes a bio-mat and a composite biological packing material fixed on the bio-mat, and the bio-mat and the composite biological packing material are inoculated with low-temperature nitrifying bacteria. The denitrification layer includes packing balls, which are doped with a slow-release carbon source and inoculated with low-temperature resistant denitrifying bacteria. The composite biological packing material of the nitrification layer includes composite biological packing balls and biological ropes connecting the composite biological packing balls; The composite bio-filler balls are selected from composite filler balls of volcanic rock and zeolite and graphene-modified ceramsite, and the specific surface area of ​​the composite filler balls of volcanic rock and zeolite is ≥500 m². 2 / m 3 The mass ratio of the volcanic rock to the zeolite is 3:2; The bio-rope is made of polylactic acid woven mesh; The preparation method of the graphene-modified ceramic particles includes the following steps: After acid washing of shale ceramsite, graphene is grown on the surface of shale ceramsite by chemical vapor deposition at a temperature of 800℃, with 3 to 5 layers of graphene. The packing balls of the denitrification layer are doped with slow-release sulfur preparation and slow-release carbon source composite particles, wherein the C / N ratio of the slow-release carbon source is ≥6; The packing balls of the denitrification layer are suspended below the bio-mat using bio-ropes; The packing balls of the denitrification layer are also loaded with anthraquinone-2-sulfonate; The low-temperature nitrifying bacteria are selected from immobilized nitrifying bacteria microcapsules and / or magnetically responsive bacterial agents, and the low-temperature nitrifying bacteria are selected from Candida nitrosamine and / or Acinetobacter pyrophila. The low-temperature resistant denitrifying bacteria are selected from at least one of Pseudomonas schlegelii, Thiobacillus, and Bacillus; the biofilm is selected from at least one of polyurethane biofilm, polyethylene biofilm, and polypropylene biofilm.

2. The composite ecological device for in-situ enhanced denitrification of low-temperature river water as described in claim 1, characterized in that, The insulation layer includes an upper light-transmitting insulation cover film and a lower insulation material layer.

3. The composite ecological device for in-situ enhanced denitrification of low-temperature river water as described in claim 2, characterized in that, The light-transmitting and heat-insulating cover film is selected from at least one of the following: a dimming film, a photothermal conversion film, and a self-cleaning ETFE film; And / or, the material of the insulation layer is selected from at least one of polyurethane foam insulation material, aerogel felt and phase change energy storage material.

4. The composite ecological device for in-situ enhanced denitrification of low-temperature river water as described in claim 1, characterized in that, The packing balls for the denitrification layer are selected from composite packing balls of volcanic rock and zeolite and / or metal-organic framework materials. The particle size of the composite packing balls of volcanic rock and zeolite is 10~20mm, and the specific surface area is ≥500 m². 2 / m 3 .

5. The composite ecological device for in-situ enhanced denitrification of low-temperature river water as described in claim 1, characterized in that, The sustained-release sulfur preparation is selected from sulfur granules and / or sodium thiosulfate-palmitite sustained-release tablets. And / or, the slow-release carbon source is selected from lignin and / or polyhydroxy fatty acid esters.

6. The application of a composite ecological device for in-situ enhanced denitrification of low-temperature river water as described in any one of claims 1 to 5, characterized in that, The composite ecological device is used for in-situ denitrification of low-temperature river water, the temperature of which is 5~10℃. The composite ecological device has an in-situ denitrification efficiency of over 50% for low-temperature river water.

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