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

Abstract

The invention belongs to the field of sewage treatment. The invention provides a manganese-loaded sulfur-rich spartina alterniflora denitrification material as well as a preparation method and application thereof, and the manganese-loaded sulfur-rich spartina alterniflora denitrification material is obtained by loading manganese oxide on alkali modified sulfur-rich spartina alterniflora or alkali modified sulfur-rich spartina alterniflora charcoal. The manganese-loaded sulfur-rich spartina alterniflora nitrogen removal material is rich in pore channels, large in specific surface area, beneficial to adsorption, catalytic oxidation and microbial biofilm formation of nitrogen pollutants, rich in carbon, sulfur and manganese elements, capable of directly releasing an organic carbon source, and capable of realizing nitrogen removal through multiple processes of coupling nitrification, manganese ammoxidation, heterotrophic denitrification, manganese autotrophic denitrification, sulfur autotrophic denitrification and the like. And high-efficiency denitrification is realized. The manganese-loaded sulfur-rich spartina alterniflora denitrification material is fixed on the surface of a hard aggregate or an elastic or soft carrier, and can be widely applied to deep denitrification of constructed wetlands, biological filters and sewage plants, rural agricultural sewage treatment and initial rainwater purification.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment, and in particular relates to a nitrogen-polluted wastewater treatment technology. Background Art

[0002] Nitrogen pollution in water bodies is a global environmental problem, mainly from agricultural runoff, industrial wastewater and domestic sewage. When nitrogen pollutants enter water bodies, they will cause eutrophication, which will in turn cause a series of ecological problems such as algal blooms and death of aquatic organisms, and threaten human health. Therefore, solving the problem of nitrogen pollution in water bodies is of great significance to protecting the ecological environment and human health.

[0003] At present, common denitrification technologies mainly include biological denitrification, chemical denitrification and physical denitrification. Biological denitrification uses the nitrification and denitrification of microorganisms to convert ammonia nitrogen into nitrogen gas, which has the advantages of low cost and no secondary pollution; chemical denitrification converts nitrogen pollutants into harmless substances through chemical reagents or catalysts, which has the characteristics of fast reaction speed and simple operation; physical denitrification mainly removes nitrogen pollutants in water through physical methods such as adsorption and precipitation, which has the advantages of high treatment efficiency and wide application range.

[0004] As an emerging functional material, manganese-rich materials have attracted widespread attention in the field of water denitrification in recent years due to their unique physical and chemical properties, such as high redox potential, good adsorption performance and biocompatibility. Manganese-rich materials can effectively remove nitrogen pollutants in water through oxidation, adsorption and other pathways, while also providing a suitable growth environment for microorganisms and promoting the biological denitrification process. However, there are some limitations to the direct application of manganese oxide minerals. The small specific surface area of ​​manganese oxide minerals leads to limited adsorption capacity, which is difficult to meet the needs of large-scale water treatment; manganese oxide has low surface activity and is difficult to effectively combine with organic pollutants and microorganisms in water, resulting in poor bioavailability and insufficient mass transfer efficiency of biochemical reactions.

[0005] If manganese oxide minerals are loaded on the surface of carbon materials, their application effect in water denitrification can be improved. Carbon materials have high specific surface area, excellent mechanical strength and good biocompatibility, which can effectively improve the adsorption capacity and stability of manganese oxide minerals. At the same time, the surface activity of carbon materials is relatively high, which can promote the effective combination of manganese oxide minerals with pollutants and microorganisms in water, and enhance their denitrification effect. For example, patent No. CN 113457639B discloses a manganese-loaded loofah fiber for adsorption catalytic denitrification and its preparation and application. Specifically, loofah with good support, porosity and strong adsorption capacity is mixed with sodium hydroxide, potassium permanganate and manganese sulfate to prepare loofah fiber loaded with manganese oxide, and it is applied to ammonia nitrogen adsorption and catalytic degradation. However, loofah is supplied as a derivative product of agricultural and sideline products, and the demand has increased significantly in recent years, and a shortage of supply has begun to appear.

[0006] Spartina alterniflora is one of the invasive plants in the global coastal salt marsh ecosystem, posing a serious threat to the biodiversity maintenance and ecological security of most coastal tidal wetlands. Due to the difficulty and cost of Spartina alterniflora prevention and control, in the management of Spartina alterniflora, on the one hand, control measures need to be taken to curb its spread rate and reduce its harm to the ecosystem; on the other hand, the rapid growth and strong stress resistance of Spartina alterniflora should be fully utilized to develop and utilize it as a resource. Compared with other plants, Spartina alterniflora has strong environmental adaptability, high antioxidant capacity, rapid growth, large biomass, and strong reproductive capacity, making it a more ideal choice for raw material development.

[0007] The resource utilization of Spartina alterniflora mainly focuses on the following three directions: 1. Fuel utilization. That is, producing biogas and preparing bio-oil through anaerobic fermentation; 2. Using it as fresh grass or extracting bio-mineral liquid for feed and fertilizer application; 3. Raw material application. Preparing biochar as an adsorbent or as a partial substitute for raw materials in pulp production; 4. Medicinal use. Using flavonoids extracted from Spartina alterniflora for anti-inflammatory, hypoglycemic, and hypolipidemic purposes.

[0008] In the field of environmental governance, the research on Spartina alterniflora is mostly focused on the field of soil or sediment substrate improvement, and biochar is made by solvent thermal method, high temperature calcination method, low temperature anoxic pyrolysis method, etc. For example, the interaction between Spartina alterniflora biochar and soil can promote the chelation of soil minerals and heavy metal cadmium (Cd), reducing the bioavailability of Cd. Patent No. CN118831556A application discloses a kind of improved biochar and its preparation method and application, and the biochar made by high temperature pyrolysis and iron modification of Spartina alterniflora is applied to the improvement of coastal wetland substrate, effectively reducing the concentration of nitrate and nitrite in sediments.

[0009] Some studies have reported the growth metabolism and microbial community response of Spartina alterniflora under sulfur stress. Spartina alterniflora may stimulate the activity of soil sulfur-reducing bacteria by releasing root exudates, increase the sulfate reduction rate of the ecosystem, and promote the formation of free sulfide. Exogenous sulfur supply can promote the growth of Spartina alterniflora and intensify the expansion of Spartina alterniflora in coastal wetlands. At the same time, Spartina alterniflora has a strong ability to absorb and accumulate sulfur, and a large amount of exogenous sulfur will promote the enrichment of sulfur in the plant tissues of Spartina alterniflora. The relevant paper pointed out that in the sulfur addition experiment, the sulfur content of the underground part of Spartina alterniflora was significantly higher than that of the neighboring reeds and salt wormwood, and the sulfur content of the aboveground part was also higher than that of reeds.

[0010] Therefore, Spartina alterniflora has a sulfur-rich endowment and has the potential to act as an inorganic electron donor to drive sulfur autotrophic denitrification. However, there are currently few studies and inventions on the resource utilization of Spartina alterniflora for water treatment and denitrification functional materials. If manganese oxide is loaded on the surface of sulfur-rich Spartina alterniflora to prepare an environmental material with adsorption, catalytic oxidation, and biological denitrification functions, it will promote the resource utilization of Spartina alterniflora in the field of water treatment, enhance the bioavailability of manganese, and help nitrification-mixed culture and denitrification synergistic denitrification. Summary of the invention

[0011] In order to solve the above problems, the present invention provides a manganese-loaded sulfur-rich Spartina alterniflora denitrification material and its preparation method and application. The manganese-loaded sulfur-rich Spartina alterniflora denitrification material of the present invention is rich in pores and has a large specific surface area, which is conducive to the adsorption, catalytic oxidation and microbial biofilm of nitrogen pollutants. It is rich in carbon elements, sulfur elements and manganese elements, and can directly release organic carbon sources. It can achieve efficient denitrification by coupling nitrification, manganese ammonia oxidation, heterotrophic denitrification, manganese autotrophic denitrification, sulfur autotrophic denitrification and other biological denitrification processes. Tests show that the application of non-biological denitrification of manganese-loaded Spartina alterniflora denitrification material of the present invention has a good removal effect on nitrate nitrogen, and its application of biological denitrification has a good removal effect on nitrate nitrogen and ammonia nitrogen.

[0012] The object of the present invention is to provide a manganese-loaded sulfur-rich Spartina alterniflora denitrification material. The manganese-loaded sulfur-rich Spartina alterniflora denitrification material is obtained by loading manganese oxide on alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar, has a particle size of 20-200 meshes, contains more than 30% atomic percentage of manganese and sulfur elements, and more than 50% by mass of manganese and sulfur elements.

[0013] In the denitrification material, manganese mainly exists in the form of manganese oxide, and the form of manganese is mainly 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 ​​(sulfur group-SH), cystine (disulfide bond-SS-), etc.

[0014] The denitrification material is rich in carbon, sulfur and manganese. Microorganisms can directly use the carbon source slowly released by Spartina alterniflora as an organic electron donor to promote heterotrophic denitrification, and can also use low-valent sulfur (S 0 , S 2- The divalent manganese generated by the biochemical process of manganese oxides (such as nitrification, manganese ammonia oxidation, heterotrophic denitrification, manganese autotrophic denitrification, sulfur autotrophic denitrification and other biological denitrification processes can be used to achieve efficient denitrification.

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

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

[0017] Preferably, the manganese-loaded Spartina alterniflora denitrification material of the present invention is obtained by mixing alkali-modified Spartina alterniflora or alkali-modified Spartina alterniflora biochar with potassium permanganate solution, and the dosage ratio of alkali-modified Spartina alterniflora or modified 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-loaded sulfur-rich Spartina alterniflora denitrification material, comprising the following steps:

[0019] The alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar and potassium permanganate solution are uniformly mixed according to the above ratio, shaken at 20-30° C. for 20-30 h, washed with deionized water and then dried to obtain a manganese-loaded sulfur-rich Spartina alterniflora denitrification material.

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

[0021] The invention provides an alkali-modified sulfur-rich Spartina alterniflora, and a preparation method thereof, comprising the steps of immersing the sulfur-rich 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°C to obtain the alkali-modified sulfur-rich Spartina alterniflora.

[0022] Alkali-modified sulfur-rich Spartina alterniflora biochar, and a preparation method thereof, comprising the steps of first heating the alkali-modified sulfur-rich Spartina alterniflora to a temperature between 290-310°C and pyrolyzing it at a constant temperature for 1-2 hours under a nitrogen atmosphere, then heating the alkali-modified sulfur-rich Spartina alterniflora to a temperature between 450-700°C and pyrolyzing it at a constant temperature for 1-2 hours, cooling naturally, washing with water to neutrality, and drying to obtain the alkali-modified sulfur-rich Spartina alterniflora biochar.

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

[0024] Specifically, sulfur-rich culture refers to planting Spartina alterniflora plants in cotton planting, immersing the roots in a solution of 90-130mM Na2S or Na2SO4, and culturing under hydroponic conditions or simulated intertidal mud conditions. The culture process conditions include: plant supplementary lighting, humidity above 60%, salinity 0.3%-1.0%, and temperature 20-30°C.

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

[0026] The manganese-loaded sulfur-rich Spartina alterniflora denitrification material of the present invention is used for sewage treatment and has the following beneficial effects:

[0027] (1) The material uses Spartina alterniflora as a skeleton material for manganese loading, which is conducive to the rapid biofilm formation of microorganisms and the rapid start-up of the biological denitrification process, and can improve the solubility and reaction activity of the manganese component and effectively prevent surface passivation;

[0028] (2) The material is loaded with manganese oxides on the surface of Spartina alterniflora and its derived biochar materials by in situ deposition, which can promote the rapid removal of ammonia nitrogen through non-biological processes such as adsorption and catalytic oxidation, and can also drive manganese ammonia oxidation (Mnammox) and promote nitrification under the action of microorganisms; the material also contains a large amount of manganese and sulfur components. Microorganisms can directly use the carbon source slowly released by Spartina alterniflora as an organic electron donor to promote heterotrophic denitrification, and can also use low-valent sulfur (S 0 , S 2- Etc.) and divalent manganese as inorganic electron donors drive autotrophic denitrification, achieving carbon-manganese-sulfur metabolism coupling to enhance denitrification. The manganese-loaded sulfur-rich Spartina alterniflora denitrification functional material can achieve synchronous nitrification and denitrification through manganese redox cycle, and can make full use of a variety of electron donors to adapt to the denitrification process under different carbon-nitrogen ratios. Tests have shown that the biological denitrification application of the manganese-loaded sulfur-rich Spartina alterniflora denitrification material of the present invention has a good removal effect on both nitrate nitrogen and ammonia nitrogen, and the material can enhance the removal efficiency of ammonia nitrogen 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 a hard aggregate by physical and chemical methods, and a suitable structural filling method can be designed according to the biofilter, artificial 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-loaded 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-loaded sulfur-rich Spartina alterniflora denitrification material of the present invention loads manganese oxide on alkali-modified sulfur-rich Spartina alterniflora in situ or loads manganese oxide after being made into biochar, and is applied to water or sediment pollution control. Biological denitrification is enhanced by coupling adsorption, oxidation and carbon-manganese-sulfur metabolism, and the simultaneous and rapid removal of nitrate nitrogen and ammonia nitrogen is achieved, and the denitrification performance is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a scanning electron micrograph of alkali-modified Spartina alterniflora SA1;

[0033] Figure 2 This is a scanning electron micrograph of manganese-loaded Spartina alterniflora SA2;

[0034] Figure 3 This is the Fourier transform infrared spectrum of Spartina alterniflora before and after manganese loading;

[0035] Figure 4 The abiotic denitrification effect of manganese-loaded Spartina alterniflora denitrification materials;

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

[0037] Figure 6 Effect of Spartina alterniflora on the removal of ammonia nitrogen under biological conditions for manganese loading. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The sulfur-rich Spartina alterniflora raw material of the manganese-loaded Spartina alterniflora denitrification material can be used directly or after being cultured in sulfur-rich conditions.

[0040] Sulfur-rich culture refers to planting Spartina alterniflora plants in cotton, immersing the roots in a solution of 90-130mM Na2S or Na2SO4, and culturing them in hydroponics or simulated intertidal mud conditions. The conditions required for the cultivation process include: plant supplementary lighting, humidity above 60%, salinity 0.3%-1%, and temperature 20-25℃.

[0041] The raw material Spartina alterniflora of the manganese-loaded Spartina alterniflora denitrification material includes Spartina alterniflora or a biochar material derived from it.

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

[0043] Step 1: immerse the 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 a temperature of 50-70° C. to obtain alkali-modified Spartina alterniflora;

[0044] Step 2: Evenly 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 at 20-30°C for 20-30h, wash with deionized water and dry to obtain manganese-loaded Spartina alterniflora.

[0045] Manganese-loaded Spartina alterniflora biochar can be prepared by the following steps:

[0046] Step 1: immerse the 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 a temperature of 50-70° C. 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° C. for constant temperature pyrolysis for 1 h, then heated to 450-700° C. for constant temperature pyrolysis for 1-2 h, cooled naturally, washed with water to neutrality, and dried to obtain a standby Spartina alterniflora biochar;

[0048] Step 3: The biochar obtained in step 2 is mixed evenly with 0.05M-0.3M potassium permanganate solution at a solid-liquid ratio of 1-2g:100-200mL, immersed at 20-30°C for 20-30h, washed with deionized water and dried to obtain manganese-loaded Spartina alterniflora biochar.

[0049] The present invention uses Spartina alterniflora to load manganese oxide to prepare a denitrification functional material, which has the following characteristics:

[0050] (1) The material source of Spartina alterniflora is rich, the price is low, the preparation process is simple, it can be mass-produced, and the resource utilization of Spartina alterniflora is realized;

[0051] (2) The manganese-loaded sulfur-rich Spartina alterniflora denitrification material of the present invention has a large specific surface area, rich pores, many active sites, and is easy for microorganisms to form biofilms. It can effectively combine physical and chemical denitrification methods such as 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 aggregates or the surface of soft, elastic fillers, and can be widely used in artificial wetlands, biofilters, deep denitrification in sewage treatment plants, rural agricultural sewage treatment, initial rainwater purification and other application scenarios to enhance the denitrification performance of wastewater.

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

[0054] The naturally harvested and dried Spartina alterniflora was crushed with a crusher, soaked in a 2.0% sodium hydroxide solution for 12 hours, washed with tap water, adjusted to pH 7.0, and dried to obtain alkali-modified Spartina alterniflora SA1. Figure 1 The energy spectrum analysis results are shown in Table 1.

[0055] Table 1 Spectral analysis results of alkali-modified Spartina alterniflora SA1

[0056]

[0057] 1 g of the above SA1 material was weighed in a 250 mL conical flask, 100 mL of 0.3 M KMnO4 solution was added, and the mixture was shaken at 100 rpm / min for 24 h at 30 ° C in a constant temperature shaking incubator, washed with deionized water and dried to obtain manganese-loaded Spartina alterniflora SA2. The scanning electron microscopy of SA2 is shown in FIG. Figure 2 The energy spectrum analysis results are shown in Table 2.

[0058] Table 2 Spectral analysis results of manganese-loaded Spartina alterniflora SA2

[0059]

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

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

[0062] In a 250 mL conical flask, add 0.1 g of the above denitrification materials SA1 and SA2, and add 100 mL of synthetic wastewater. - -N concentration is about 200mg / L or NH4 + -N concentration is about 200mg / L. After 24h of reaction, sample the effluent for NO3 testing. - -N and NH4 + -N concentration, calculate the removal capacity of nitrogen pollutants by Spartina alterniflora loaded with manganese under abiotic conditions (in mg / g), the results are shown in Figure 4 .Depend on Figure 4 It can be seen that the abiotic nitrogen removal of manganese-loaded 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 Application of manganese-loaded sulfur-rich Spartina alterniflora denitrification material in biological denitrification

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

[0065] Add 100mL of NO3 with a concentration of about 200mg / L - -N or NH4 with a concentration of about 75 mg / L + -N synthetic wastewater. Samples were taken at different time points to test the nitrogen pollutant concentration in the effluent. The results are as follows Figure 5 and Figure 6 .Depend on Figure 5 It can be seen that the nitrate-nitrogen removal rate of Spartina alterniflora loaded with manganese in 24 hours under biological conditions was 28.2%, and the removal capacity was as high as 55.8 mgN / g. Figure 6 It can be seen that the ammonia nitrogen removal rate of manganese-loaded Spartina alterniflora under biological conditions was 15.3% in 24 hours, and the removal capacity reached 11.3 mgN / g.

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

[0067] In summary, the present invention prepares manganese-loaded 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 drives electron transfer with the help of carbon, manganese, and sulfur metabolic coupling to achieve efficient simultaneous nitrification and denitrification.

[0068] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those skilled in the relevant technical field may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by the claims.

Claims

1. A manganese-loaded sulfur-rich Spartina alterniflora denitrification material, characterized in that: The manganese-loaded 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 oxide, has a particle size of 20-200 meshes, contains more than 30% atomic percentage of manganese and sulfur elements, and more than 50% by mass of manganese and sulfur elements.

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

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

4. A method for preparing a manganese-loaded sulfur-rich Spartina alterniflora denitrification material as claimed in claim 3, characterized in that: The method comprises the following steps: mixing alkali-modified sulfur-rich Spartina alterniflora or alkali-modified sulfur-rich Spartina alterniflora biochar with potassium permanganate solution in a proportion, shaking at 20-30° C. for 20-30 hours, washing with deionized water and then drying to obtain a manganese-loaded sulfur-rich Spartina alterniflora denitrification material. Wherein, 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 Spartina alterniflora is obtained by immersing the 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°C.

6. The preparation method according to claim 4, characterized in that: The alkali-modified sulfur-rich Spartina alterniflora biochar is obtained by first heating the alkali-modified sulfur-rich Spartina alterniflora to 290-310° C., pyrolyzing at a constant temperature for 1-2 hours, then heating the alkali-modified sulfur-rich Spartina alterniflora to 450-700° C., pyrolyzing at a constant temperature for 1-2 hours, cooling the alkali-modified Spartina alterniflora biochar to neutrality, and drying the alkali-modified Spartina alterniflora biochar.

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

8. The preparation method according to claim 7, characterized in that: The sulfur-rich culture comprises the following steps: planting the Spartina alterniflora plants in planting cotton, immersing the root system in a 90-130 mM Na2S or Na2SO4 solution, and culturing under hydroponic or simulated intertidal mud conditions, wherein the culture process conditions include: irradiation with plant supplementary lighting, humidity above 60%, salinity of 0.3%-1.0%, and temperature of 20-30°C.

9. An application of a manganese-loaded sulfur-rich Spartina alterniflora denitrification material prepared by the preparation method according to any one of claims 1 to 3 or any one of claims 4 to 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 artificial wetlands, biofilters, deep denitrification of sewage plants, rural agricultural sewage treatment, and initial rainwater purification.

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