A method for preparing biochar from spartina and application of the biochar in denitrification and phosphorus removal

Abstract

The application provides a method for preparing biochar from Spartina alterniflora and application thereof in nitrogen and phosphorus removal, and belongs to the technical field of biological materials. The application realizes high-value utilization of invasive plants and reduces environmental pollution by converting widely distributed Spartina alterniflora into biochar. The biochar has excellent performance in nitrogen and phosphorus removal, effectively improves water eutrophication, improves water quality and protects aquatic ecosystems. The preparation method is simple, the cost is reduced, and the method is convenient for large-scale production. The method is environment-friendly, does not produce secondary pollution and meets the sustainable development. The application not only provides a new environmental remediation material, but also opens up a new way for biomass resource utilization, has significant economic and social benefits, improves public health, improves the quality of life and protects biodiversity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological materials, and particularly relates to a method for preparing biochar from Spartina alterniflora and application of the biochar in denitrification and phosphorus removal. BACKGROUND

[0002] In the field of environmental pollution control and ecological restoration, biochar has attracted extensive attention as a potential environmental restoration material. Biochar is a high-carbon porous material obtained by pyrolysis of biomass under anaerobic or limited oxygen conditions, and has a large specific surface area and a developed pore structure. These characteristics make biochar have certain application potential in soil improvement, pollution control and carbon sequestration and emission reduction.

[0003] However, the existing biochar preparation technology has some limitations. First, the traditional biochar preparation method usually depends on specific biomass resources, which limits the source of raw materials and the stability of supply. For example, some methods may require specific agricultural waste or specific biomass materials, which may pose challenges in raw material acquisition and cost control. In addition, the production cost of biochar is relatively high, and may face technical and economic challenges in large-scale application.

[0004] In terms of denitrification and phosphorus removal, existing technologies often rely on chemical agents and microbial treatment, which may have problems such as low efficiency, high cost or secondary pollution. Although biochar has certain denitrification and phosphorus removal capacity, its effect is affected by preparation conditions, raw material characteristics and application methods, and in practical application, it often needs to be used in cooperation with other technologies to improve the treatment efficiency. In addition, the application of biochar in water denitrification and phosphorus removal also faces the challenges of how to improve its adsorption performance and stability, and how to realize the long-term effectiveness and environmental friendliness of biochar.

[0005] Chinese patent CN201210078182.5 describes a method for producing biochar from Spartina alterniflora and green waste, although this method achieves resource utilization to some extent, the preparation process is complex, and the requirements for the environment and equipment are high, which limits its wide application.

[0006] Existing technologies have been exploring more efficient and low-cost biochar preparation methods, and how to improve the application effect of biochar in environmental restoration. Although there have been some progress, there is still a lot of room for improvement in the optimization of biochar preparation process, cost control, and improvement of its performance in denitrification and phosphorus removal. Therefore, developing new biochar preparation technology and exploring its new application in environmental restoration has become a research hotspot in this field. SUMMARY

[0007] The application aims to provide a method for preparing biochar from Spartina alterniflora and application thereof in nitrogen and phosphorus removal, which has excellent effects.

[0008] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0009] The application provides a preparation method of Spartina alterniflora biochar, which comprises the following steps.

[0010] The Spartina alterniflora is mixed with auxiliary materials, and pyrolysis treatment is performed after natural fermentation to obtain Spartina alterniflora biochar.

[0011] The auxiliary materials contain wheat straw, corn stalks and bentonite.

[0012] Preferably, the Spartina alterniflora is 40-60 parts by weight, the wheat straw is 20-40 parts by weight, the corn stalks are 10-20 parts by weight, and the bentonite is 3-8 parts by weight.

[0013] Preferably, the volume of the material subjected to natural fermentation is greater than 1 cubic meter.

[0014] Preferably, the time for natural fermentation is 20-40 days.

[0015] Preferably, the Spartina alterniflora is crushed before use, and the particle size of the crushed Spartina alterniflora is less than 0.5 mm.

[0016] Preferably, in the pyrolysis treatment, the pyrolysis temperature is 500-700 DEG C.

[0017] In the pyrolysis treatment, the heating rate is 5-10 DEG C / min.

[0018] In the pyrolysis treatment, the holding time is 20-50 min.

[0019] Preferably, the pyrolysis treatment is performed in a nitrogen atmosphere, and the nitrogen flow rate is 0.3-0.5 m 3 / s.

[0020] Preferably, the biochar further comprises pH adjustment to 6.5-7.0.

[0021] The pH adjustment adopts a citric acid solution as an adjusting agent, and the concentration of the citric acid solution is 3-5%.

[0022] The application provides Spartina alterniflora biochar prepared by the above-mentioned preparation method.

[0023] The application provides application of the above-mentioned Spartina alterniflora biochar in water body nitrogen and phosphorus removal.

[0024] The application has the following technical effects and advantages:

[0025] The present application realizes the high-value utilization of this widely distributed invasive plant resource by converting Spartina alterniflora into biochar. This conversion not only reduces the environmental burden of invasive plants, but also provides new possibilities for the recycling of biomass resources. Through this innovative method, Spartina alterniflora is no longer a simple invasive plant, but an environmentally friendly material with high adsorption performance, which has important significance in resource recycling and environmental protection.

[0026] In terms of environmental remediation, Spartina alterniflora biochar shows excellent ability, especially in the application of denitrification and phosphorus removal. This biochar can effectively improve the eutrophication problem of water bodies and improve the water environmental quality, which plays an important role in restoring and protecting the health of aquatic ecosystems. By adsorbing nitrogen and phosphorus compounds in water, biochar helps to reduce the nutrient load in water bodies, thereby inhibiting the overgrowth of algae and maintaining the ecological balance of water bodies.

[0027] The method for preparing Spartina alterniflora biochar is simple and easy to operate, without the need for complex equipment and processes, which makes it have obvious advantages in large-scale production and application. The simple preparation process reduces production costs while ensuring efficient output of biochar, which lays the foundation for the commercial production and widespread application of biochar.

[0028] Environmental friendliness is another highlight of the present application. The preparation and application process of biochar does not produce secondary pollution, fully meeting the requirements of sustainable development. This material, while adsorbing and removing pollutants in water bodies, does not cause new burdens to the environment, and is a truly green solution.

[0029] The present application not only provides an effective environmental remediation material, but also opens up new ways for the utilization of biomass resources such as Spartina alterniflora. This innovative application not only has significant economic benefits by reducing environmental pollution control costs and improving resource utilization efficiency, but also has far-reaching social benefits, including improving public health, improving quality of life and protecting biodiversity. Through this innovative technology, we can more effectively utilize natural resources while protecting and improving the environment we live in. DETAILED DESCRIPTION

[0030] The present application provides a preparation method of Spartina alterniflora biochar, comprising the following steps:

[0031] Mixing Spartina alterniflora with auxiliary materials, natural fermentation and pyrolysis treatment to obtain Spartina alterniflora biochar;

[0032] The auxiliary materials contain wheat straw, corn stalks and bentonite.

[0033] The application utilizes wheat straw, corn stalk and bentonite as composite adjuvants to prepare biochar with Spartina alterniflora by pyrolysis. The physical and chemical properties of these adjuvants can enhance the adsorption and catalytic performance of biochar. Wheat straw and corn stalk are rich in cellulose and lignin. These organic substances can form more carbon skeleton and microporous structure during pyrolysis, thereby increasing the specific surface area and porosity of biochar and improving its adsorption capacity for nitrogen and phosphorus. At the same time, these biomasses can release potassium, magnesium and other minerals during pyrolysis. These minerals can serve as plant nutrients and promote the metabolic activity of microorganisms, further improving the nitrogen and phosphorus removal efficiency. As a natural clay mineral, bentonite has a large specific surface area and cation exchange capacity, which can adsorb nitrogen and phosphorus compounds in water. Meanwhile, its layered structure may form a complex with biochar during pyrolysis, enhancing the stability and adsorption performance of biochar. The application successfully combines the properties of these adjuvants and prepares biochar with more excellent performance in nitrogen and phosphorus removal.

[0034] In the application, preferably, the Spartina alterniflora is 40-60 parts by weight, the wheat straw is 20-40 parts by weight, the corn stalk is 10-20 parts by weight, and the bentonite is 3-8 parts by weight. Preferably, the volume of the naturally fermented material is more than 1 cubic meter. Preferably, the natural fermentation time is 20-40 days. During the natural fermentation process in the application, the metabolic activity of microorganisms can pretreat the raw materials. This process helps to decompose complex organic substances in the raw materials, producing more soluble organic carbon and nutrients. These substances can be converted into surface functional groups of biochar during subsequent pyrolysis, thereby increasing the chemical activity and adsorption capacity of biochar. Metabolic products such as organic acids produced by microbial activity can etch the pore structure of biochar to some extent, increasing its specific surface area and porosity. This improved pore structure helps to improve the adsorption performance of biochar, making it more effective in environmental remediation processes such as nitrogen and phosphorus removal.

[0035] In the application, preferably, the Spartina alterniflora is crushed before use, and the particle size of the crushed material is less than 0.5 mm. Preferably, in the pyrolysis process, the pyrolysis temperature is 500-700℃; in the pyrolysis process, the heating rate is 5-10℃ / min; and in the pyrolysis process, the holding time is 20-50 min.

[0036] The pyrolysis treatment parameters of the present application can obtain optimal biochar performance, and the pyrolysis temperature is a key factor affecting the structure and properties of biochar. Within this temperature range, the high molecular organic substances such as hemicellulose, cellulose and lignin in the biomass raw material can be fully decomposed to form rich pore structure and large specific surface area. Lower pyrolysis temperature may result in incomplete decomposition of organic matter, while higher temperature may result in excessive graphitization of biochar, thereby reducing its porosity. The temperature range provided by the present application helps to balance the carbonization degree and pore development of biochar, and obtain suitable adsorption performance and structural stability.

[0037] The heating rate determines the speed of biomass raw material pyrolysis, and further affects the physical and chemical properties of biochar. A slower heating rate may result in excessive oxidation of biochar, while fast heating may result in insufficient decomposition of organic matter. The heating rate provided by the present application can ensure that the biomass raw material is gradually and uniformly decomposed during pyrolysis, which is beneficial to the formation of stable pore structure and suitable surface functional groups, thereby improving the adsorption performance of biochar.

[0038] The holding time is the key to ensure the full decomposition and rearrangement of biomass raw material during pyrolysis. Shorter holding time may result in incomplete decomposition of organic matter, while longer holding time may result in excessive solidification of biochar structure. The holding time provided by the present application can ensure that the organic matter in biochar is fully decomposed, while maintaining a certain degree of carbonization, avoiding excessive graphitization, thereby obtaining higher biochar quality and adsorption performance.

[0039] The present application optimizes the preparation process of biochar by precisely controlling the pyrolysis temperature, heating rate and holding time, so that the obtained biochar has suitable pore structure, specific surface area and surface functional groups, thereby exhibiting excellent performance in environmental remediation applications such as denitrification and phosphorus removal. This fine-tuned pyrolysis treatment parameter helps to maximize the performance of biochar and improve its efficiency and effect in environmental governance.

[0040] In the present application, preferably, the pyrolysis treatment is carried out in a nitrogen atmosphere, and the nitrogen flow is 0.3-0.5 m 3 / s. Preferably, the biochar further comprises adjusting the pH to 6.5-7.0; the pH adjustment uses citric acid solution as the adjusting agent, and the concentration of the citric acid solution is 3-5%.

[0041] The present application provides Spartina alterniflora biochar prepared by the above preparation method.

[0042] The present application provides the application of the above Spartina alterniflora biochar in water body denitrification and phosphorus removal, including the following application methods:

[0043] Direct addition:

[0044] The Spartina alterniflora biochar prepared by the application is directly put into the water body. This method is simple and direct, and is suitable for small-scale treatment or situations that require a quick response. The biochar directly removes nitrogen and phosphorus in the water through adsorption.

[0045] Immobilized bed technology:

[0046] Construct a biochar immobilized bed, fill the Spartina alterniflora biochar provided by the application in the reactor, and when the water body flows through, nitrogen and phosphorus are adsorbed and removed by the biochar. This method is suitable for continuous treatment of water bodies and can continuously and stably purify water quality.

[0047] Mixed with adsorption materials:

[0048] The Spartina alterniflora biochar provided by the application is mixed with other adsorption materials (such as zeolite, activated carbon, etc.) and then put into the water body. This combination can improve the adsorption efficiency and broaden the adsorption range, and is suitable for the removal of various pollutants.

[0049] Compound with microorganisms:

[0050] The Spartina alterniflora biochar provided by the application is compounded with specific functional microorganisms (such as denitrifying bacteria and phosphorus-removing bacteria) and then put into the water body. The biochar serves as a carrier for microorganisms, providing a growth environment and enhancing the denitrification and phosphorus removal effect of microorganisms.

[0051] Symbiotic system with aquatic plants:

[0052] Aquatic plants are planted in the water body, and the Spartina alterniflora biochar provided by the application is added in the root area of the plants. The biochar can promote plant growth and, together with the plant root system, improve the removal efficiency of nitrogen and phosphorus.

[0053] As a flocculant auxiliary material:

[0054] When using a chemical flocculant to treat the water body, the Spartina alterniflora biochar provided by the application is added as an auxiliary material. The biochar can adsorb nitrogen and phosphorus released during the flocculation process, improve the flocculation effect, and reduce the amount of chemical flocculant used.

[0055] Combined with sediment improvement:

[0056] The Spartina alterniflora biochar provided by the application is mixed into the sediment of the water body, which improves the physical and chemical properties of the sediment, promotes the fixation and transformation of nitrogen and phosphorus in the sediment, and reduces the release of nitrogen and phosphorus in the sediment.

[0057] Dynamic circulation treatment system:

[0058] A dynamic circulation system is constructed, and the Spartina alterniflora biochar provided by the application is placed in the circulation filter unit. When the water body circulates through the filter material, nitrogen and phosphorus are continuously removed, which is suitable for long-term maintenance of aquaculture and landscape water bodies.

[0059] The above application modes can be selected and adjusted according to specific water body conditions and treatment targets to achieve optimal denitrification and phosphorus removal effects.

[0060] The technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0061] Example 1

[0062] Raw material selection

[0063] Switchgrass was selected as the main pyrolysis material, and straw, corn stalks and bentonite were selected as the composite auxiliary materials.

[0064] Pretreatment

[0065] The switchgrass and auxiliary materials were thoroughly washed with clean water to remove sand and impurities, and the washed raw materials were dried in a natural environment to a moisture content of less than 10%. The dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0066] Pyrolysis: The pretreated switchgrass, straw, corn stalks and bentonite were mixed uniformly in a ratio of 50%, 30%, 15% and 5%, and the mixed material (2 cubic meters) was sealed and stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under a nitrogen atmosphere, with a pyrolysis temperature of 550°C, a heating rate of 5°C / min, a holding time of 30 min, and a nitrogen flow rate of 0.32 cubic meters / second.

[0067] Post-treatment

[0068] After pyrolysis, the material was naturally cooled to room temperature in a N2 atmosphere, sieved through a 40-mesh screen to remove oversized particles, and finally mixed with 5% citric acid solution to adjust the pH to 7.0 for standby use.

[0069] Example 2

[0070] Raw material selection

[0071] Switchgrass was selected as the main pyrolysis material, and straw, corn stalks and bentonite were selected as the composite auxiliary materials.

[0072] Pretreatment

[0073] The switchgrass and auxiliary materials were thoroughly washed with clean water to remove sand and impurities, and the washed raw materials were dried in a natural environment to a moisture content of less than 10%. The dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0074] Pyrolysis: The pretreated switchgrass, wheat straw, corn stalk and bentonite were mixed evenly according to the ratio of 50%, 30%, 15% and 5%, and the mixture (2 cubic meters) was stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under nitrogen atmosphere, the pyrolysis temperature was set to 600°C, the heating rate was 5°C / min, the holding time was 30 min, and the nitrogen flow rate was maintained at 0.32 cubic meters / second.

[0075] Post-treatment

[0076] After pyrolysis, it was naturally cooled to room temperature in N2 atmosphere; sieved through a 40 mesh screen to remove oversized particles, and finally mixed with 5% citric acid solution to adjust the pH to 7.0 for standby.

[0077] Example 3

[0078] Raw material selection

[0079] Switchgrass was selected as the main pyrolysis material, and wheat straw, corn stalk and bentonite were selected as the composite auxiliary materials.

[0080] Pretreatment

[0081] The switchgrass and auxiliary materials were thoroughly washed with clean water to remove dirt and impurities, and the washed raw materials were dried in the natural environment to a moisture content of less than 10%. The dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0082] Pyrolysis: The pretreated switchgrass, wheat straw, corn stalk and bentonite were mixed evenly according to the ratio of 50%, 30%, 15% and 5%, and the mixture (2 cubic meters) was stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under nitrogen atmosphere, the pyrolysis temperature was set to 600°C, the heating rate was 5°C / min, the holding time was 30 min, and the nitrogen flow rate was maintained at 0.32 cubic meters / second.

[0083] Post-treatment

[0084] After pyrolysis, it was naturally cooled to room temperature in N2 atmosphere; sieved through a 40 mesh screen to remove oversized particles, and finally mixed with 5% citric acid solution to adjust the pH to 7.0 for standby.

[0085] Example 4

[0086] Raw material selection

[0087] Switchgrass was selected as the main pyrolysis material, and wheat straw, corn stalk and bentonite were selected as the composite auxiliary materials.

[0088] Pretreatment

[0089] The Spartina alterniflora and the auxiliary materials are washed thoroughly with clean water to remove the sand and impurities. The washed raw materials are dried in the natural environment until the moisture content is less than 10%. The dried raw materials are crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0090] Pyrolysis: The pretreated Spartina alterniflora, wheat straw, corn stalks, and bentonite are mixed uniformly at a ratio of 50%, 30%, 15%, and 5%. The mixed material (2 cubic meters) is stored sealed for 30 days to promote natural fermentation. Anaerobic pyrolysis is carried out under a nitrogen atmosphere, with a pyrolysis temperature set at 550°C, a heating rate of 5°C / min, a holding time of 45 min, and a nitrogen flow rate maintained at 0.32 cubic meters / second.

[0091] Post-processing

[0092] After pyrolysis is completed, natural cooling is performed in an N2 atmosphere to room temperature. Screening is performed through a 40-mesh screen to remove oversized particles. Finally, the biochar is mixed with a 5% citric acid solution to adjust the pH to 7.0, ready for use.

[0093] Example 5

[0094] Raw material selection

[0095] Spartina alterniflora is selected as the main pyrolysis material, and wheat straw, corn stalks, and bentonite are selected as the auxiliary composite materials.

[0096] Pretreatment

[0097] The Spartina alterniflora and the auxiliary materials are washed thoroughly with clean water to remove the sand and impurities. The washed raw materials are dried in the natural environment until the moisture content is less than 10%. The dried raw materials are crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0098] Pyrolysis: The pretreated Spartina alterniflora, wheat straw, corn stalks, and bentonite are mixed uniformly at a ratio of 50%, 30%, 15%, and 5%. The mixed material (2 cubic meters) is stored sealed for 30 days to promote natural fermentation. Anaerobic pyrolysis is carried out under a nitrogen atmosphere, with a pyrolysis temperature set at 550°C, a heating rate of 5°C / min, a holding time of 30 min, and a nitrogen flow rate maintained at 0.4 cubic meters / second.

[0099] Post-processing

[0100] After pyrolysis is completed, natural cooling is performed in an N2 atmosphere to room temperature. Screening is performed through a 40-mesh screen to remove oversized particles. Finally, the biochar is mixed with a 5% citric acid solution to adjust the pH to 7.0, ready for use.

[0101] Example 6

[0102] Raw material selection

[0103] The Spartina alterniflora was selected as the main pyrolysis material, and the wheat straw, corn stalk and bentonite were selected as the composite auxiliary materials.

[0104] pretreatment

[0105] The Spartina alterniflora and the auxiliary materials were washed thoroughly with clean water to remove the sand and impurities, and the washed raw materials were dried in the natural environment to a moisture content of less than 10%, and the dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0106] pyrolysis: the pretreated Spartina alterniflora, wheat straw, corn stalk and bentonite were mixed uniformly at a ratio of 45%, 35%, 15% and 5%, and the mixed material (2 cubic meters) was sealed and stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under a nitrogen atmosphere, the pyrolysis temperature was set to 550℃, the heating rate was 5℃ / min, the holding time was 30 min, and the nitrogen flow rate was maintained at 0.32 cubic meters / second.

[0107] post-treatment

[0108] After pyrolysis, the temperature was naturally cooled to room temperature in a N2 atmosphere; screening was performed through a 40-mesh screen to remove oversized particles, and finally the biochar was mixed with a 5% citric acid solution to adjust the pH to 7.0 for standby.

[0109] Example 7

[0110] raw material selection

[0111] The Spartina alterniflora was selected as the main pyrolysis material, and the wheat straw, corn stalk and bentonite were selected as the composite auxiliary materials.

[0112] pretreatment

[0113] The Spartina alterniflora and the auxiliary materials were washed thoroughly with clean water to remove the sand and impurities, and the washed raw materials were dried in the natural environment to a moisture content of less than 10%, and the dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0114] pyrolysis: the pretreated Spartina alterniflora, wheat straw, corn stalk and bentonite were mixed uniformly at a ratio of 50%, 30%, 15% and 5%, and the mixed material (2 cubic meters) was sealed and stored for 45 days to promote natural fermentation. Anaerobic pyrolysis was carried out under a nitrogen atmosphere, the pyrolysis temperature was set to 550℃, the heating rate was 5℃ / min, the holding time was 30 min, and the nitrogen flow rate was maintained at 0.32 cubic meters / second.

[0115] post-treatment

[0116] After pyrolysis, the temperature was naturally cooled to room temperature in a N2 atmosphere; screening was performed through a 40-mesh screen to remove oversized particles, and finally the biochar was mixed with a 5% citric acid solution to adjust the pH to 7.0 for standby.

[0117] Example 8

[0118] Raw material selection

[0119] The Spartina alterniflora was selected as the main pyrolysis material, and the wheat straw, corn stalk and bentonite were selected as the composite auxiliary materials.

[0120] Pre-treatment

[0121] The Spartina alterniflora and the auxiliary materials were thoroughly washed with clean water to remove the sand and impurities. The washed raw materials were air-dried to a moisture content of less than 10% under natural conditions, and the dried raw materials were crushed to a particle size of less than 0.5 mm using an industrial crusher.

[0122] Pyrolysis: The pre-treated Spartina alterniflora, wheat straw, corn stalk and bentonite were mixed uniformly in a ratio of 50%, 30%, 15% and 5%, and the mixed material (2 cubic meters) was sealed and stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under a nitrogen atmosphere, with a pyrolysis temperature of 550°C, a heating rate of 5°C / min, a holding time of 30 min, and a nitrogen flow rate of 0.32 cubic meters / second.

[0123] Post-treatment

[0124] After pyrolysis, the material was naturally cooled to room temperature in a N2 atmosphere, screened through a 40-mesh screen to remove oversized particles, and finally mixed with a 5% citric acid solution to adjust the pH to 7.0 for use.

[0125] Example 9

[0126] Raw material selection

[0127] The Spartina alterniflora was selected as the main pyrolysis material, and the wheat straw, corn stalk and bentonite were selected as the composite auxiliary materials.

[0128] Pre-treatment

[0129] The Spartina alterniflora and the auxiliary materials were thoroughly washed with clean water to remove the sand and impurities. The washed raw materials were air-dried to a moisture content of less than 10% under natural conditions, and the dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0130] Pyrolysis: The pre-treated Spartina alterniflora, wheat straw, corn stalk and bentonite were mixed uniformly in a ratio of 50%, 30%, 15% and 5%, and the mixed material (2 cubic meters) was sealed and stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under a nitrogen atmosphere, with a pyrolysis temperature of 550°C, a heating rate of 5°C / min, a holding time of 30 min, and a nitrogen flow rate of 0.32 cubic meters / second.

[0131] Post-treatment

[0132] After pyrolysis, the sample was naturally cooled to room temperature under N2 atmosphere; sieved through a 40 mesh screen to remove oversized particles, and finally mixed with 3% citric acid solution to adjust pH to 7.0 for standby.

[0133] Example 10

[0134] Raw material selection

[0135] Spartina alterniflora was selected as the main pyrolysis material, and wheat straw, corn stalks and bentonite were selected as the composite auxiliary materials.

[0136] Pre-treatment

[0137] The Spartina alterniflora and auxiliary materials were thoroughly washed with clean water to remove dirt and impurities, and the washed raw materials were dried in the natural environment to a moisture content of less than 10%, and the dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0138] Pyrolysis: The pretreated Spartina alterniflora, wheat straw, corn stalks and bentonite were mixed evenly in a ratio of 50%, 30%, 15% and 5%, and the mixed material (2 cubic meters) was sealed and stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under a nitrogen atmosphere, with a pyrolysis temperature of 550°C, a heating rate of 5°C / min, a holding time of 30 min, and a nitrogen flow rate of 0.32 cubic meters / second.

[0139] Post-treatment

[0140] After pyrolysis, the sample was naturally cooled to room temperature under N2 atmosphere; sieved through a 40 mesh screen to remove oversized particles, and finally mixed with 3% citric acid solution to adjust pH to 7.0 for standby.

[0141] Comparative Example 1

[0142] Raw material selection

[0143] Spartina alterniflora was selected as the main pyrolysis material.

[0144] Pre-treatment

[0145] The Spartina alterniflora was thoroughly washed with clean water to remove dirt and impurities, and the washed raw materials were dried in the natural environment to a moisture content of less than 10%, and the dried raw materials were crushed to a particle size of less than 0.25 mm using an industrial crusher.

[0146] Pyrolysis: The pretreated Spartina alterniflora was sealed and stored for 30 days to promote natural fermentation. Anaerobic pyrolysis was carried out under a nitrogen atmosphere, with a pyrolysis temperature of 550°C, a heating rate of 5°C / min, a holding time of 30 min, and a nitrogen flow rate of 0.32 cubic meters / second.

[0147] Post-treatment

[0148] After pyrolysis is complete, cool naturally to room temperature in an N2 atmosphere; screen through a 40-mesh screen to remove oversized particles, and finally mix the biochar with a 5% citric acid solution to adjust the pH to 6.5, ready for use.

[0149] Experimental Example

[0150] The biochar produced in Example 1 and Comparative Example 1 was used for denitrification and phosphorus removal applications:

[0151] Experimental Conditions:

[0152] Biochar dosage: 0.5 g / L, accurately weighed according to the volume of the experimental water sample.

[0153] Hydraulic retention time: 24 hours, to ensure that the water sample stays in the experimental device for enough time for the biochar to fully react with the pollutants in the water body.

[0154] Stirring speed: 200 rpm, to ensure uniform distribution of biochar particles in the water sample and improve contact efficiency.

[0155] Other data:

[0156] Water sample volume: 5 L.

[0157] Experimental repeatability: To ensure the reliability of the experimental results, each experimental condition was repeated 3 times.

[0158] Data recording: All parameters during the experiment were recorded in detail, including stirring speed, pH value, dissolved oxygen concentration, temperature, etc.

[0159] Experimental Steps:

[0160] Before starting the experiment, accurately weigh the biochar and add it to the water sample; stir the water sample at the set stirring speed to ensure uniform distribution of the biochar; after the experiment is completed, filter the water sample through a filter and funnel to remove the biochar particles.

[0161] Detect the water body indicators before and after treatment:

[0162] Total nitrogen (TN):

[0163] Using the alkaline potassium persulfate digestion ultraviolet spectrophotometric method (HJ 636-2012), the total nitrogen content was calculated by measuring the absorption intensity of the water sample in the ultraviolet region.

[0164] Total phosphorus (TP):

[0165] Using the ammonium molybdate spectrophotometric method (GB 11893-89), the total phosphorus content was calculated by measuring the absorbance of the water sample at a specific wavelength.

[0166] pH: Directly measure the pH value of water sample using pH meter.

[0167] Dissolved oxygen (DO): Measure the concentration of dissolved oxygen in water sample by electrochemical probe method using portable dissolved oxygen meter.

[0168] Evaluation of nitrogen and phosphorus removal efficiency

[0169] By comparing the nitrogen and phosphorus concentrations in water before and after adding biochar, the nitrogen and phosphorus removal efficiency is calculated:

[0170] Nitrogen removal efficiency = (TN 处理前 -TN 处理后 ) / TN 处理前 × 100%

[0171] Phosphorus removal efficiency = (TP 处理前 -TP 处理后 ) / TP 处理前 × 100%

[0172] In the embodiment of the present application, the water treatment property indicators before treatment are: total nitrogen (TN) 30.5 mg / L, total phosphorus (TP) 3.8 mg / L, dissolved oxygen (DO) 4.5 mg / L, and pH 7.2.

[0173] The water treatment property indicators after treatment are shown in Table 1 below:

[0174] Table 1 Water treatment property indicators after treatment

[0175]

[0176] The evaluation results of nitrogen and phosphorus removal efficiency are shown in Table 2 below:

[0177] Table 2 Evaluation results of nitrogen and phosphorus removal efficiency

[0178]

[0179]

[0180] Analysis of variance

[0181] Total nitrogen (TN): F 1,18) = 18.34, p = 0.001

[0182] Total phosphorus (TP): F 1,18) = 25.67, p = 0.0001

[0183] The significance analysis results show that: total nitrogen (TN), there is a significant difference between Example 1 and Comparative Example 1 at the significance level of 0.05. Total phosphorus (TP), there is a significant difference between Example 1 and Comparative Example 1 at the significance level of 0.05.

[0184] Total nitrogen (TN): the average denitrification efficiency of example 1 is 90.0%, and that of comparative example 1 is 59.1%. The variance analysis shows that there is a significant difference between the two, indicating that the biochar treatment of example 1 is better.

[0185] Total phosphorus (TP): the average phosphorus removal efficiency of example 1 is 92.1%, and that of comparative example 1 is 71.1%. The variance analysis shows that there is a significant difference between the two, indicating that the biochar treatment of example 1 is also more effective in removing phosphorus.

[0186] From the above results, it can be seen that the biochar prepared in example 1 has higher efficiency in denitrification and phosphorus removal. By optimizing the mixing ratio of raw materials and pyrolysis conditions, the pore structure and surface functional groups of the biochar are improved, thereby enhancing its adsorption capacity for nitrogen, phosphorus and other pollutants. In practical application, it has significant advantages and provides a new idea and method for water pollution control.

[0187] The above is only the preferred embodiment of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method of producing a Spartina biomass charcoal, characterized by, The method comprises the following steps: mixing Spartina alterniflora with auxiliary materials, and then pyrolyzing the mixture after natural fermentation to obtain Spartina alterniflora biochar; the auxiliary materials contain wheat straw, corn stalks and bentonite.

2. The production method according to claim 1, characterized by, The Spartina alterniflora is 40-60 parts by weight, the wheat straw is 20-40 parts by weight, the corn stalks are 10-20 parts by weight, and the bentonite is 3-8 parts by weight.

3. The preparation method according to claim 1, characterized in that, The volume of the material after natural fermentation is more than 1 cubic meter.

4. The production method according to claim 3, characterized by, The time for natural fermentation is 20-40 days.

5. The preparation method according to claim 1, characterized in that, The Spartina alterniflora is crushed before use, and the particle size of the crushed Spartina alterniflora is less than 0.5 mm.

6. The method of claim 1, wherein, In the pyrolysis process, the pyrolysis temperature is 500-700℃. In the pyrolysis process, the heating rate is 5-10℃ / min. In the pyrolysis process, the holding time is 20-50 min.

7. The preparation method according to claim 6, characterized in that, The pyrolysis treatment is carried out in a nitrogen atmosphere, the nitrogen flow being between 0.3 and 0.5 m 3 / s.

8. The method of claim 1, wherein, The biochar further comprises pH adjustment to 6.5-7.

0. The pH adjustment uses a citric acid solution as the adjusting agent, and the concentration of the citric acid solution is 3-5%.

9. Spartina alterniflora biochar prepared by the preparation method of any one of claims 1-8.

10. Application of the Spartina alterniflora biochar of claim 9 in water denitrification and phosphorus removal.

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