Manganese-loaded sulfur-rich spartina alterniflora denitrification material, and preparation method and application thereof

Abstract

This invention belongs to the field of wastewater treatment. It provides a manganese-supported sulfur-rich Spartina alterniflora denitrification material, its preparation method, and its application. This manganese-supported sulfur-rich Spartina alterniflora denitrification material is obtained by alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar loaded with manganese oxides. The manganese-supported sulfur-rich Spartina alterniflora denitrification material of this invention has abundant pores and a large specific surface area, which is beneficial for the adsorption, catalytic oxidation, and microbial biofilm formation of nitrogen pollutants. It is also rich in carbon, sulfur, and manganese, and can directly release organic carbon sources. It can achieve efficient denitrification through multiple processes such as coupled nitrification, manganese ammonium oxidation, heterotrophic denitrification, manganese autotrophic denitrification, and sulfur autotrophic denitrification. The manganese-supported sulfur-rich Spartina alterniflora denitrification material of this invention is fixed on the surface of hard aggregates, elastic or soft carriers, and can be widely used in constructed wetlands, biological filters, deep denitrification in wastewater treatment plants, rural and agricultural wastewater treatment, and initial rainwater purification.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, specifically relating to nitrogen-polluted wastewater treatment technology. Background Technology

[0002] Nitrogen pollution in water bodies is a global environmental problem, primarily originating from agricultural runoff, industrial wastewater, and domestic sewage. Once nitrogen pollutants enter water bodies, they lead to eutrophication, triggering a series of ecological problems such as algal blooms and the death of aquatic organisms, and threatening human health. Therefore, addressing nitrogen pollution in water bodies is of great significance for protecting the ecological environment and human health.

[0003] Currently, common denitrification technologies mainly include biological denitrification, chemical denitrification, and physical denitrification. Biological denitrification utilizes the nitrification and denitrification processes of microorganisms to convert ammonia nitrogen into nitrogen gas, offering advantages such as low cost and no secondary pollution. Chemical denitrification uses chemical reagents or catalysts to convert nitrogen pollutants into harmless substances, characterized by rapid reaction speed and simple operation. Physical denitrification primarily removes nitrogen pollutants from water through physical methods such as adsorption and precipitation, offering advantages such as high treatment efficiency and wide applicability.

[0004] Manganese-rich materials, as an emerging functional material, have attracted widespread attention in the field of water denitrification in recent years due to their unique physicochemical properties, such as high redox potential, good adsorption performance, and biocompatibility. Manganese-rich materials can effectively remove nitrogenous pollutants from water through multiple pathways, including oxidation and adsorption, while also providing a suitable growth environment for microorganisms and promoting biological denitrification. However, the direct application of manganese oxide minerals has some limitations. The small specific surface area of ​​manganese oxide minerals results in limited adsorption capacity, making it difficult to meet the needs of large-scale water treatment; the low surface activity of manganese oxides makes it difficult to effectively bind with organic pollutants and microorganisms in water, leading to poor bioavailability and insufficient mass transfer efficiency in biochemical reactions.

[0005] Loading manganese oxide minerals onto the surface of carbon materials can improve their effectiveness in denitrification of water. Carbon materials possess high specific surface area, excellent mechanical strength, and good biocompatibility, which can effectively enhance the adsorption capacity and stability of manganese oxide minerals. Simultaneously, the high surface activity of carbon materials promotes the effective binding of manganese oxide minerals with pollutants and microorganisms in water, thereby enhancing the denitrification effect. For example, patent number CN 113457639B discloses a manganese-loaded loofah fiber for adsorption and catalytic denitrification, its preparation, and application. Specifically, manganese oxide-loaded loofah fiber is prepared by mixing and modifying well-supported, porous, and highly adsorbent loofah with sodium hydroxide, potassium permanganate, and manganese sulfate, and then applying it to ammonia nitrogen adsorption and catalytic degradation. However, as a derivative product of agricultural byproducts, the demand for loofah has increased significantly in recent years, and a supply shortage has begun to emerge.

[0006] Spartina alterniflora is one of the invasive plants in global coastal salt marsh ecosystems, posing a serious threat to the biodiversity maintenance and ecological security of most coastal wetlands. Due to the difficulty and high cost of controlling Spartina alterniflora, its management requires, on the one hand, control measures to curb its spread and reduce its harm to the ecosystem; on the other hand, it is essential to fully utilize its rapid growth and strong resilience for resource development and utilization. Compared to other plants, Spartina alterniflora's strong environmental adaptability, high antioxidant capacity, rapid growth, large biomass, and strong reproductive capacity make it a more ideal raw material choice for resource development.

[0007] The resource utilization of Spartina alterniflora mainly revolves around the following three directions: 1. Fuel utilization: producing biogas and preparing bio-oil through anaerobic fermentation; 2. Application as fresh grass or extracting bio-mineral liquid for feed and fertilizer; 3. Raw material utilization: preparing biochar for use as an adsorbent or as a partial substitute raw material in pulp production; 4. Medicinal use: utilizing Spartina alterniflora extracts such as flavonoids for anti-inflammatory, hypoglycemic, and lipid-lowering effects.

[0008] In the field of environmental remediation, research on Spartina alterniflora has largely focused on soil or sediment bottom improvement, employing methods such as solvothermal methods, high-temperature calcination, and low-temperature anoxic pyrolysis to produce biochar. For example, the interaction between Spartina alterniflora biochar and soil can promote the chelation of soil minerals with the heavy metal cadmium (Cd), reducing Cd bioavailability. Patent application CN118831556A discloses an improved biochar, its preparation method, and its application, applying biochar prepared from the high-temperature pyrolysis and iron modification of Spartina alterniflora to the improvement of coastal wetland bottom sediments, effectively reducing the concentrations of nitrate and nitrite nitrogen in sediments.

[0009] Several studies have reported on the growth, metabolism, and microbial community responses of *Spartina alterniflora* under sulfur stress. *Spartina alterniflora* may stimulate the activity of soil sulfur-reducing bacteria by releasing root exudates, thereby increasing the sulfate reduction rate of the ecosystem and promoting the formation of free sulfides. Exogenous sulfur supply can promote the growth of *Spartina alterniflora* and exacerbate its expansion in coastal wetlands. Simultaneously, *Spartina alterniflora* has a strong capacity for sulfur absorption and accumulation; large amounts of exogenous sulfur will promote the enrichment of sulfur in *Spartina alterniflora* plant tissues. Some papers have indicated that in sulfur addition experiments, the sulfur content in the underground parts of *Spartina alterniflora* was significantly higher than that in neighboring *Phragmites australis* and *Salix matsudana*, and the sulfur content in the aboveground parts was also higher than that in *Phragmites australis*.

[0010] Therefore, Spartina alterniflora, with its sulfur-rich endowment, possesses the potential to drive sulfur autotrophic denitrification as an inorganic electron donor. However, there is currently little research and invention on the resource utilization of Spartina alterniflora in water treatment denitrification functional materials. If manganese oxides are loaded onto the surface of sulfur-rich Spartina alterniflora to prepare environmental materials with adsorption, catalytic oxidation, and biological denitrification functions, it will promote the resource utilization of Spartina alterniflora in the water treatment field, enhance the bioavailability of manganese, and facilitate synergistic denitrification through nitrification-co-culture denitrification. Summary of the Invention

[0011] To address the aforementioned problems, this invention provides a manganese-supported sulfur-rich Spartina alterniflora denitrification material, its preparation method, and its applications. This manganese-supported sulfur-rich Spartina alterniflora denitrification material possesses abundant pores and a large specific surface area, which is beneficial for the adsorption, catalytic oxidation, and microbial biofilm formation of nitrogen pollutants. Simultaneously, it is rich in carbon, sulfur, and manganese, enabling the direct release of organic carbon sources. It can achieve highly efficient nitrogen removal through coupled nitrification, manganese ammonia oxidation, heterotrophic denitrification, manganese autotrophic denitrification, and sulfur autotrophic denitrification processes. Tests show that the non-biological denitrification application of this manganese-supported Spartina alterniflora denitrification material has a good removal effect on nitrate nitrogen, while its biological denitrification application has good removal effects on both nitrate nitrogen and ammonia nitrogen.

[0012] The purpose of this invention is to provide a manganese-supported sulfur-rich Spartina alterniflora denitrification material. This manganese-supported sulfur-rich Spartina alterniflora denitrification material is obtained by alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar loaded with manganese oxides. Its particle size is 20-200 mesh, and its manganese and sulfur atomic percentages exceed 30% and its manganese and sulfur mass percentages exceed 50%.

[0013] In this denitrification material, manganese mainly exists in the form of manganese oxides, with the dominant form being Mn(Ⅲ) / Mn(Ⅳ). Organic sulfur accounts for more than 80% of the total sulfur content in plant tissues, and sulfur exists in the form of reduced organic sulfides, such as cysteine ​​(sulfo-SH) and cystine (disulfide bond-SS-).

[0014] This denitrification material is rich in carbon, sulfur, and manganese. Microorganisms can directly utilize the slow-released carbon source from Spartina alterniflora as an organic electron donor to promote heterotrophic denitrification. It can also utilize low-valent sulfur (S...) 0 S 2- Divalent manganese generated from the biochemical processes of manganese oxides (etc.) and manganese oxides serves as an inorganic electron donor to drive autotrophic denitrification, thereby achieving enhanced denitrification through carbon-manganese-sulfur metabolic coupling. By coupling multiple biological denitrification processes such as nitrification, manganese ammonia oxidation, heterotrophic denitrification, manganese autotrophic denitrification, and sulfur autotrophic denitrification, efficient denitrification is achieved.

[0015] Furthermore, the specific surface area of ​​the denitrification material obtained by alkali-modified sulfur-rich Spartina alterniflora loaded with manganese is 20-100 m².2 / g.

[0016] The specific surface area of ​​the denitrification material obtained by loading manganese onto alkali-modified sulfur-rich Spartina alterniflora biochar is 300-500 m². 2 / g.

[0017] Preferably, the manganese-supported sulfur-rich Spartina alterniflora denitrification material of the present invention is obtained by mixing alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar with potassium permanganate solution, wherein the ratio of alkali-modified sulfur-rich Spartina alterniflora or modified sulfur-rich Spartina alterniflora biochar to potassium permanganate dry matter is 1g:0.002-0.03mol.

[0018] The present invention also aims to provide a method for preparing the above-mentioned manganese-supported sulfur-rich Spartina alterniflora denitrification material, comprising the following steps:

[0019] Alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar was mixed with potassium permanganate solution in the above ratio, and the mixture was shaken at 20-30℃ for 20-30 hours. After washing with deionized water and drying, manganese-supported sulfur-rich Spartina alterniflora denitrification material was obtained.

[0020] The concentration of the potassium permanganate solution is 0.05M-0.3M.

[0021] In this invention, the preparation method of alkali-modified sulfur-enriched Spartina alterniflora includes the following steps: immersing sulfur-enriched Spartina alterniflora in a 0.5%-3.0% sodium hydroxide solution for 12-24 hours, washing with deionized water, adjusting the pH to 6.5-7.5, and drying at a temperature of 50-70℃ to obtain alkali-modified sulfur-enriched Spartina alterniflora.

[0022] The preparation method of alkali-modified sulfur-rich Spartina alterniflora biochar includes the following steps: under a nitrogen atmosphere, the above-mentioned alkali-modified sulfur-rich Spartina alterniflora is first heated to a certain temperature between 290-310℃ and kept at a constant temperature for 1-2 hours, then heated to a certain temperature between 450-700℃ and kept at a constant temperature for 1-2 hours, naturally cooled, washed with water until neutral, and dried to obtain alkali-modified sulfur-rich Spartina alterniflora biochar.

[0023] Furthermore, the aforementioned sulfur-enriched Spartina alterniflora is obtained by culturing Spartina alterniflora with sulfur or by directly using sulfur-enriched Spartina alterniflora.

[0024] Specifically, sulfur-enriched culture refers to planting Spartina alterniflora plants in cotton fields, immersing the roots in a solution containing 90-130 mM Na2S or Na2SO4, and cultivating them hydroponically or under simulated intertidal mud conditions. The cultivation conditions include: plant supplemental lighting, humidity above 60%, salinity 0.3%-1.0%, and temperature 20-30℃.

[0025] The present invention also aims to provide the application of the above-mentioned manganese-loaded sulfur-rich Spartina alterniflora denitrification material, which is fixed on the surface of hard aggregate, elastic or soft filler, and applied in constructed wetlands, biological filters, deep denitrification in sewage treatment plants, rural and agricultural sewage treatment, and initial rainwater purification.

[0026] The manganese-supported sulfur-rich Spartina alterniflora denitrification material of this invention has the following beneficial effects when used in wastewater treatment:

[0027] (1) This material uses Spartina alterniflora as a manganese-loaded skeleton material, which is conducive to the rapid biofilm formation of microorganisms and the rapid start-up of the biological denitrification process. In addition, it can improve the solubility and reactivity of manganese components and effectively prevent surface passivation.

[0028] (2) This material, through in-situ deposition, loads manganese oxides onto the surface of Spartina alterniflora and its derived biochar materials. This can promote rapid ammonia nitrogen removal through abiotic processes such as adsorption and catalytic oxidation, and can also drive manganese ammonia oxidation (Mnammox) and promote nitrification under microbial action. The material also contains a large amount of manganese and sulfur components. Microorganisms can directly utilize the slowly released carbon source from Spartina alterniflora as an organic electron donor to promote heterotrophic denitrification, and can also utilize low-valent sulfur (S... 0 S 2- Manganese (and other inorganic electron donors) and divalent manganese drive autotrophic denitrification, achieving enhanced denitrification through carbon-manganese-sulfur metabolic coupling. This manganese-supported sulfur-rich Spartina alterniflora denitrification material can achieve simultaneous nitrification and denitrification through manganese redox cycles, and can fully utilize multiple electron donors to adapt to denitrification processes under different carbon-nitrogen ratios. Tests show that the biological denitrification application of the manganese-supported sulfur-rich Spartina alterniflora denitrification material of this invention has good removal effects on both nitrate nitrogen and ammonia nitrogen. This material can enhance ammonia nitrogen removal efficiency under low dissolved oxygen conditions.

[0029] (3) The manganese-loaded sulfur-rich Spartina alterniflora denitrification material of the present invention can be fixed on the surface of an elastic carrier or hard aggregate by physical and chemical methods. The appropriate structural filling method can be designed according to the biological filter, constructed wetland, etc. At the same time, it can be coupled with water treatment technologies such as bioelectrochemical systems to further improve the denitrification efficiency.

[0030] (4) The manganese-supported sulfur-rich Spartina alterniflora denitrification material of the present invention provides a theoretical and practical basis for the resource utilization of Spartina alterniflora as an environmental functional material other than an adsorbent.

[0031] In summary, the manganese-supported sulfur-rich Spartina alterniflora denitrification material of this invention involves alkali-modified sulfur-rich Spartina alterniflora on-site loading of manganese oxides or manganese oxides after being made into biochar. When applied to the treatment of water or sediment pollution, it enhances biological denitrification through adsorption, oxidation, and carbon-manganese-sulfur metabolic coupling, achieving simultaneous and rapid removal of nitrate nitrogen and ammonia nitrogen, and significantly improving denitrification performance. Attached Figure Description

[0032] Figure 1 Scanning electron microscope image of alkali-modified Spartina alterniflora SA1;

[0033] Figure 2 Scanning electron microscope image of manganese-loaded Spartina alterniflora SA2;

[0034] Figure 3 Fourier transform infrared spectra of Spartina alterniflora before and after manganese loading;

[0035] Figure 4 The non-biological denitrification effect of manganese-supported Spartina alterniflora denitrification material;

[0036] Figure 5 The effect of manganese-loaded Spartina alterniflora on nitrate removal under biological conditions;

[0037] Figure 6 The effect of manganese-loaded Spartina alterniflora on ammonia nitrogen removal under biological conditions. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] The sulfur-enriched Spartina alterniflora, the raw material for manganese-supported Spartina alterniflora denitrification materials, can be used directly or after sulfur-enriched cultivation.

[0040] Sulfur-enriched culture refers to planting Spartina alterniflora plants in cotton fields, immersing their roots in a solution containing 90-130 mM Na₂S or Na₂SO₄, and cultivating them hydroponically or under simulated intertidal mud conditions. The necessary conditions for cultivation include: plant grow lights, humidity above 60%, salinity 0.3%-1%, and temperature 20-25℃.

[0041] The raw material for manganese-loaded Spartina alterniflora denitrification materials is Spartina alterniflora, which includes Spartina alterniflora or its derivative biochar materials.

[0042] Manganese-loaded Spartina alterniflora can be prepared via the following steps:

[0043] Step 1: Immerse Spartina alterniflora in a 0.5-3.0% sodium hydroxide solution for 12-24 hours, wash with deionized water, adjust the pH to 6.5-7.5, and dry at 50-70℃ to obtain alkali-modified Spartina alterniflora.

[0044] Step 2: Mix the alkali-modified Spartina alterniflora obtained in Step 1 with 0.05M-0.3M potassium permanganate solution at a solid-liquid ratio of 1-2g:100-200mL. Soak the mixture at 20-30℃ for 20-30h, wash with deionized water, and then dry to obtain manganese-loaded Spartina alterniflora.

[0045] Manganese-supported Spartina alterniflora biochar can be prepared via the following steps:

[0046] Step 1: Immerse Spartina alterniflora in a 0.5%-3.0% sodium hydroxide solution for 12-24 hours, wash with deionized water, adjust the pH to 6.5-7.5, and dry at 50-70℃ to obtain alkali-modified Spartina alterniflora.

[0047] Step 2: Under a nitrogen atmosphere, the alkali-modified Spartina alterniflora obtained in Step 1 is first heated to 290-310℃ and kept at a constant temperature for 1 hour, then heated to 450-700℃ and kept at a constant temperature for 1-2 hours. After natural cooling, it is washed with water until neutral and dried to obtain Spartina alterniflora biochar for later use.

[0048] Step 3: Mix the biochar obtained in Step 2 with 0.05M-0.3M potassium permanganate solution at a solid-liquid ratio of 1-2g:100-200mL until homogeneous. Soak the mixture at 20-30℃ for 20-30h, wash with deionized water and dry to obtain manganese-supported Spartina alterniflora biochar.

[0049] This invention uses on-site loading of manganese oxides in Michelia alba to prepare denitrification functional materials, which have the following characteristics:

[0050] (1) Spartina alterniflora has abundant and inexpensive raw materials, a simple preparation process, can be mass-produced, and has realized the resource utilization of Spartina alterniflora.

[0051] (2) The manganese-supported sulfur-rich Spartina alterniflora denitrification material of the present invention has a large specific surface area, abundant pores, many active sites, and is easy for microorganisms to attach to the biofilm. It can effectively combine the physical and chemical denitrification method of adsorption and catalytic oxidation with biological methods such as nitrification-denitrification.

[0052] (3) The manganese-loaded sulfur-rich Spartina alterniflora denitrification material of the present invention can be further dispersed on the surface of hard inert aggregate or soft, elastic filler, and can be widely used in artificial wetlands, biological filters, deep denitrification of sewage treatment plants, rural and agricultural sewage treatment, initial rainwater purification and other application scenarios, thereby enhancing the denitrification performance of wastewater.

[0053] Example 1: Preparation of manganese-supported sulfur-rich Spartina alterniflora denitrification material

[0054] Naturally harvested and dried Spartina alterniflora was pulverized using a pulverizer, soaked in a 2.0% sodium hydroxide solution for 12 hours, washed with tap water, and the pH was adjusted to 7.0. After drying, alkali-modified Spartina alterniflora SA1 was obtained. Scanning electron microscopy (SEM) images of SA1 are shown below. Figure 1 The results of the energy dispersive spectroscopy analysis are shown in Table 1.

[0055] Table 1. Energy dispersive spectroscopy analysis results of alkali-modified Spartina alterniflora SA1

[0056]

[0057] 1 g of the above SA1 material was weighed into a 250 mL Erlenmeyer flask, and 100 mL of 0.3 M KMnO4 solution was added. The mixture was shaken at 100 rpm / min for 24 h at 30 °C in a constant temperature shaking incubator. After washing with deionized water and drying, manganese-supported Spartina alterniflora SA2 was obtained. The scanning electron microscope image of SA2 is shown below. Figure 2 The results of the energy dispersive spectroscopy analysis are shown in Table 2.

[0058] Table 2. Energy dispersive spectroscopy analysis results of manganese-loaded Spartina alterniflora SA2

[0059]

[0060] Fourier transform infrared spectra of Spartina alterniflora before and after manganese loading are shown below. Figure 3 As shown, Figure 3 CO represents the original Spartina alterniflora, C1 represents the alkali-modified Spartina alterniflora, and MC represents the manganese-supported Spartina alterniflora.

[0061] Application Example 1: Non-biological denitrification application of manganese-supported sulfur-rich Spartina alterniflora denitrification material

[0062] Add 0.1g of the above-mentioned denitrification materials SA1 and SA2 to a 250mL conical flask, respectively, and then add 100mL of synthesis wastewater. The synthesis wastewater contains NO3. - -N concentration is approximately 200 mg / L or NH4+. + The NO3 concentration was approximately 200 mg / L. Samples were taken from the effluent 24 hours after the reaction to test for NO3. - -N and NH4 + -N concentration was used to calculate the removal capacity (in mg / g) of nitrogen pollutants by manganese-loaded sulfur-rich Spartina alterniflora under abiotic conditions. The results are shown in […]. Figure 4 .Depend on Figure 4 It can be seen that the non-biological denitrification of manganese-supported Spartina alterniflora denitrification material has a good removal effect on nitrate nitrogen, with a removal capacity of 13.7 mgN / g.

[0063] Application Example 2: Biological denitrification application of manganese-supported sulfur-rich Spartina alterniflora denitrification material

[0064] Two pieces of polyurethane cotton (1cm×1cm×1cm) containing 0.1g SA1 and 0.1g SA2 were respectively filled into two 250mL miniature anaerobic bottles. The bottles were then inoculated with activated sludge from the secondary sedimentation tank (MLVSS≈200mg / L) and allowed to stand for 3 days to allow biofilm formation.

[0065] Add 100 mL of NO3 with a concentration of approximately 200 mg / L - -N or NH4 at a concentration of approximately 75 mg / L + -N synthesis wastewater. The concentration of nitrogen pollutants in the effluent was measured at different time points, and the results are as follows: Figure 5 and Figure 6 .Depend on Figure 5 It was found that manganese-supported Spartina alterniflora achieved a nitrate nitrogen removal rate of 28.2% under biological conditions after 24 hours, with a removal capacity as high as 55.8 mg N / g. Figure 6 It can be seen that the ammonia nitrogen removal rate of manganese-supported Spartina alterniflora under biological conditions was 15.3% and the removal capacity reached 11.3 mg N / g.

[0066] Therefore, the non-biological denitrification of the manganese-supported Spartina alterniflora denitrification material of the present invention has a good removal effect on nitrate nitrogen, and the biological denitrification application of the manganese-supported sulfur-rich Spartina alterniflora denitrification material has a good removal effect on both nitrate nitrogen and ammonia nitrogen.

[0067] In summary, this invention prepares manganese-supported sulfur-rich Spartina alterniflora, utilizes the carbon- and sulfur-rich characteristics of Spartina alterniflora to promote mixed-culture denitrification, utilizes manganese oxides to enhance ammonia nitrogen removal, and leverages carbon-manganese-sulfur metabolic coupling to drive electron transfer, thereby achieving efficient and simultaneous nitrification and denitrification.

[0068] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A manganese-supported sulfur-rich Spartina alterniflora denitrification material, characterized in that, The manganese-supported sulfur-rich Spartina alterniflora denitrification material is obtained by alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar loaded with manganese oxides. Its particle size is 20-200 mesh, and its manganese and sulfur atomic percentages exceed 30% and its manganese and sulfur mass percentages exceed 50%.

2. The manganese-supported sulfur-rich Spartina alterniflora denitrification material according to claim 1, wherein the denitrification material obtained by alkali-modified sulfur-rich Spartina alterniflora loaded with manganese has a specific surface area of ​​20-100 m². 2 / g, the specific surface area of ​​the denitrification material obtained by loading manganese onto alkali-modified sulfur-rich Spartina alterniflora biochar is 300-500 m² / g. 2 / g.

3. The manganese-supported sulfur-rich Spartina alterniflora denitrification material according to claim 2, characterized in that, The manganese-loaded sulfur-rich Spartina alterniflora denitrification material is obtained by mixing alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar with potassium permanganate solution. The ratio of the amount of alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar to potassium permanganate dry matter is 1g:0.002-0.03mol.

4. A method for preparing manganese-supported sulfur-rich Spartina alterniflora denitrification material as described in claim 3, characterized in that, The process includes the following steps: alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar is mixed evenly with potassium permanganate solution according to a specified ratio; the mixture is shaken at 20-30℃ for 20-30 hours; after washing with deionized water, it is dried to obtain manganese-supported sulfur-rich Spartina alterniflora denitrification material. The concentration of the potassium permanganate solution is 0.05M-0.3M.

5. The preparation method according to claim 4, characterized in that, The alkali-modified sulfur-enriched Spartina alterniflora is obtained by immersing sulfur-enriched Spartina alterniflora in a 0.5%-3.0% sodium hydroxide solution for 12-24 hours, washing it with deionized water, adjusting the pH to 6.5-7.5, and drying it at a temperature of 50-70℃.

6. The preparation method according to claim 4, characterized in that, The alkali-modified sulfur-enriched Spartina alterniflora biochar is obtained by first heating the alkali-modified sulfur-enriched Spartina alterniflora to 290-310℃ and pyrolyzing it at a constant temperature for 1-2 hours, then heating it to 450-700℃ and pyrolyzing it at a constant temperature for 1-2 hours, cooling it down, washing it with water until it is neutral, and then drying it.

7. The preparation method according to claim 5 or 6, characterized in that, The sulfur-enriched Spartina alterniflora is obtained by culturing Spartina alterniflora with sulfur or by directly using sulfur-enriched Spartina alterniflora.

8. The preparation method according to claim 7, characterized in that, The sulfur-enriched culture includes the following steps: planting Spartina alterniflora plants in cotton, immersing the roots in a 90-130mM Na2S or Na2SO4 solution, and cultivating them hydroponically or under simulated intertidal mud conditions. The cultivation conditions include: plant supplemental lighting, humidity above 60%, salinity 0.3%-1.0%, and temperature 20-30℃.

9. The application of a manganese-supported sulfur-rich Spartina alterniflora denitrification material prepared by the preparation method according to any one of claims 1-3 or any one of claims 4-6 or 8, characterized in that, The manganese-loaded sulfur-rich Spartina alterniflora denitrification material is fixed on the surface of hard aggregate, elastic or soft carrier, and applied in constructed wetlands, biological filters, deep denitrification in sewage treatment plants, rural and agricultural wastewater treatment, and initial rainwater purification.

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