In-situ control covering material for lake polluted sediment and preparation method thereof

Abstract

This invention provides an in-situ controlled cover material for lake sediment and its preparation method, belonging to the field of water treatment technology. The cover material provided by this invention has a strong ability to reduce various pollutants in water, effectively improving water quality and transforming it towards a healthy and clean state. It creates a favorable aquatic environment for the survival and reproduction of aquatic organisms in the aquatic ecosystem, contributing to the restoration and enhancement of lake ecological functions. The sediment cover material of this invention can effectively act on the sediment, successfully inhibiting the release of pollutants into the water, thereby effectively reducing the diffusion of pollution from within the lake and providing habitat conditions for ecological restoration. It has significant application value in maintaining the balance and stability of the entire lake ecosystem, restoring the lake's ecological landscape, and ensuring the ecological security of surrounding areas, providing an effective new approach and method for lake pollution control and ecological restoration.

Description

Technical Field

[0001] This invention relates to the field of water pollution remediation technology, and in particular to in-situ control and covering materials for polluted lake sediments and their preparation methods. Background Technology

[0002] With the acceleration of global industrialization and urbanization, and the increasing frequency of agricultural production activities, pollution sources such as industrial wastewater, agricultural runoff, and urban sewage are continuously discharged into rivers, eventually accumulating in lakes and reservoirs. Damage to the health of lake water environments often manifests as reduced water transparency, excessive algae growth, and water quality deterioration, severely impacting the ecological functions of lakes and the surrounding landscape. For example, explosive algal growth forms thick algal blooms on the water surface, not only hindering sunlight penetration and affecting the photosynthesis of underwater plants, but also decomposing after death and consuming large amounts of oxygen in the water, causing hypoxia, which in turn leads to the mass death of aquatic organisms, disrupting the balance of the lake ecosystem, reducing the depth diversity and stability of aquatic life, and the deteriorating water quality also fails to meet people's diverse needs for lake water for viewing, irrigation, drinking, and aquaculture.

[0003] Lake sediments, as both a source and sink of pollutants, play a crucial role in the material cycle and evolution of lakes. For a long time, some of the nutrients such as nitrogen and phosphorus, as well as heavy metal pollutants, entering lakes settle to the lake bottom through physical, chemical, and biological processes, accumulating continuously in the sediment. However, sediments are not simply sites of pollutant accumulation; they undergo complex material exchange processes with the overlying water. Under specific environmental conditions, such as the influence of temperature, water flow, and microbial activity, nutrients and heavy metals in the sediment can be released back into the water, becoming a significant endogenous source of eutrophication in lakes. This continuously provides nutrients for the growth of algae and other plankton, further exacerbating lake pollution and posing a significant challenge to lake management. Simply controlling external pollution sources to reduce their impact is often insufficient to fundamentally solve the problem of lake ecological restoration; therefore, it is essential to simultaneously address the endogenous pollution source—the sediment.

[0004] Currently, the main technical means for treating polluted lake sediments include physical dredging, chemical remediation, and bioremediation, but all have certain limitations. Removing sediment from lakes through mechanical excavation, while directly removing large amounts of pollutants, is a massive undertaking with high costs. Furthermore, the dredging process can severely damage the lake's benthic ecosystem, and subsequent sediment disposal is a challenging issue; improper handling can lead to secondary pollution. Using chemical agents to react with pollutants in the sediment, such as adding lime to fix heavy metals or control phosphorus release, can be problematic. Excessive use of chemicals may alter the water's pH and other chemical properties, toxicizing aquatic organisms. Moreover, the remediation effect is often unsustainable, with pollutants potentially being released again over time. Utilizing microorganisms and aquatic plants to degrade or absorb pollutants in the sediment is also an option. However, bioremediation is typically slow and requires strict environmental conditions, such as suitable temperature and nutrients for microbial growth and reproduction. In cases of heavily polluted sediments, bioremediation alone is often insufficient to quickly and effectively purify the sediment and control eutrophication.

[0005] Given the numerous shortcomings of existing remediation technologies, the development of an efficient, economical, and environmentally friendly in-situ control technology for polluted lake sediments is particularly urgent. In-situ control technology can directly act on polluted sediments without disrupting the lake's benthic ecosystem, effectively inhibiting the release of pollutants from the sediments into the water, reducing endogenous pollution at its source. Simultaneously, by combining multiple remediation mechanisms, it accelerates the sediment purification process, thereby achieving the goals of mitigating lake eutrophication, improving lake water quality, and restoring lake ecosystem functions. This has significant practical implications for lake aquatic ecological environment protection and sustainable development.

[0006] In summary, in order to better address the problem of lake ecological restoration and overcome the limitations of existing sediment treatment technologies, it is necessary to develop an innovative in-situ control technology for polluted lake sediments, namely the technical solution involving the combination of aluminum-based composite materials and microbial agents involved in this invention. This technology has significant research value and application prospects. Summary of the Invention

[0007] The purpose of this invention is to provide an in-situ control cover material for polluted lake sediment and its preparation method, which can effectively reduce the diffusion of pollution from within lakes and provide ideal habitat conditions for aquatic ecological restoration.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides an in-situ control cover material for polluted lake sediment, comprising an aluminum-based composite material and a microbial agent;

[0010] The microbial agent contains nitrifying bacteria, Pseudomonas mendoza, and Bacillus subtilis.

[0011] Preferably, the ratio of nitrifying bacteria, Pseudomonas mendoza, and Bacillus subtilis in the microbial agent is 1:1.5-2.5:0.5-1.5.

[0012] Preferably, it includes the following steps:

[0013] Activated alumina powder, bentonite, diatomaceous earth, polyethylene glycol and sodium carboxymethyl cellulose are mixed to obtain a mud-like material;

[0014] The mud-like material is extruded, dried, and sintered to obtain an aluminum-based composite material.

[0015] Preferably, it includes the following steps:

[0016] Microbial agents were obtained by mixing, fixing, and embedding bacterial solutions of nitrifying bacteria, Pseudomonas mendoza, and Bacillus subtilis.

[0017] Preferably, the diatomaceous earth is calcined at 600-800°C for 2-3 hours before mixing.

[0018] Preferably, the mass ratio of the activated alumina powder: bentonite: diatomite is 4.5-5.5: 2.5-3.5: 1.5-2.5.

[0019] Preferably, the amount of polyethylene glycol used is 0.5% to 2% of the total mass of the raw materials;

[0020] The amount of sodium carboxymethyl cellulose used is 0.3% to 1% of the total mass of the raw materials.

[0021] Preferably, the sintering treatment is performed at a temperature of 300–500°C for 2–3 hours.

[0022] Preferably, the diameter of the extruded material particles is 1-3 cm and the length is 4-6 cm;

[0023] The dosage of the aluminum-based composite material is 5–20 kg / m³. 2 .

[0024] Preferably, the fixation and embedding method is sodium alginate-calcium chloride embedding method, and the diameter of the material after fixation and embedding is 2-3 mm;

[0025] The dosage of the microbial agent is 100-300 cells / m³. 2 .

[0026] The technical effects and advantages of this invention are as follows:

[0027] The beneficial effects of this invention lie in the significant results achieved through in-situ covering treatment of polluted lake sediment using a combination of aluminum-based composite materials and microbial agents. Regarding the water body, the total nitrogen, total phosphorus, ammonia nitrogen, and heavy metal content in the treated area all showed a significant decreasing trend over time, fully demonstrating that the materials and agents provided by this invention have a strong ability to reduce various pollutants in the water, effectively improving water quality and transforming it towards a healthy and clean state. This creates a favorable aquatic environment for the survival and reproduction of aquatic organisms in the aquatic ecosystem, contributing to the restoration and enhancement of lake ecological functions. At the sediment level, the total nitrogen, total phosphorus, heavy metal, and organic matter content in the treated area continuously decreases over time, indicating a continuous reduction in nutrients and pollutants in the sediment, and effective improvement of the sediment environment.

[0028] The sediment covering material of this invention can effectively act on polluted sediment, successfully inhibit the release of pollutants into the water body, thereby inhibiting the resuspension of lake sediment and preventing the risk of upward exchange of soluble nutrients. It has important application significance for maintaining the balance and stability of the entire lake ecosystem, restoring the healthy water ecological cycle of the lake, and ensuring the ecological security of the surrounding areas. It provides an effective new idea and method for lake ecological restoration. Detailed Implementation

[0029] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0030] Example 1

[0031] Prepare the ingredients:

[0032] Activated alumina powder: Activated alumina powder with a particle size of 200 mesh and a purity of 99.99% is selected as the main aluminum source for aluminum-based composite materials.

[0033] Bentonite: Sodium-based bentonite with a montmorillonite content of over 80% (in this example, the montmorillonite content of this Ayong product is 90%) is selected, and after grinding, it is passed through a 200-mesh sieve.

[0034] Diatomaceous earth: Select high-quality diatomaceous earth, calcine at 700℃ for 2.5 hours, and then crush it through a 150-mesh sieve.

[0035] Additives: Polyethylene glycol (PEG-4000) as a dispersant, sodium carboxymethyl cellulose (CMC) as a thickener and stabilizer.

[0036] Premix: Weigh each raw material according to the mass ratio of activated alumina powder: bentonite: diatomaceous earth = 5:3:2, put them into a high-speed mixer, add 1% of polyethylene glycol (PEG-4000) of the total mass of raw materials, and stir at 800 r / min for 20 minutes to make the raw materials fully mixed and uniform to obtain the premix.

[0037] Kneading: Slowly add an appropriate amount of deionized water to the premix, and at the same time add sodium carboxymethyl cellulose (CMC) at 0.5% of the total mass of the raw materials. Continue to stir and knead until a mud-like material with certain plasticity, uniform moisture and no obvious particle agglomeration is formed.

[0038] Shaping: The kneaded mud material is extruded into a cylindrical shape (2cm in diameter and 5cm in length) using an extruder, which facilitates subsequent application and covering operations.

[0039] Drying and sintering: The shaped material is placed in a ventilated drying oven and dried at 60°C for 12 hours to remove moisture. Then, the dried material is transferred to a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and sintered at this temperature for 3 hours to ensure tight bonding between the raw materials, improve the strength and stability of the composite material, and finally obtain the finished aluminum-based composite material.

[0040] Preparation of microbial agents

[0041] The ratio of nitrifying bacteria (Bio-74091, Nitrobacter Sp., purchased from Beijing Bio-74091 ... 8 A mixed microbial culture was prepared by combining the microbial culture (CFU / mL). To improve the survival rate and stability of the microorganisms in the lake sediment environment, the microbial culture was immobilized using a sodium alginate-calcium chloride encapsulation method. The specific operation was as follows: the microbial culture was mixed with a certain concentration (2%) sodium alginate solution at a volume ratio of 1:1, and then slowly dripped into a 2% calcium chloride solution using a syringe to form gel beads with a diameter of approximately 2.5 mm. These beads were then allowed to solidify in the calcium chloride solution for 1 hour, and then rinsed 2-3 times with physiological saline to obtain the immobilized microbial agent.

[0042] Application in in-situ cover of polluted lake sediment

[0043] Preparation before deployment

[0044] Sediment pretreatment: The polluted sediment of the lake to be treated is simply leveled to remove large debris and garbage from the surface, making the sediment surface relatively flat and facilitating the uniform laying of subsequent covering materials.

[0045] Application Planning: Based on factors such as the lake's area, shape, and pollution level, the application areas and quantities of aluminum-based composite materials and microbial agents should be rationally planned. Generally, for heavily polluted areas, the application density should be appropriately increased. A preliminary estimate can be made based on a standard of 10 kg of aluminum-based composite material (with a thickness of approximately 5 cm) and 200 microbial agent gel balls per square meter, followed by fine-tuning based on actual conditions.

[0046] Deployment Operation

[0047] Aluminum-based composite material application: The prepared aluminum-based composite material is evenly applied to the surface of the lake sediment by manual throwing or mechanical spreading, ensuring a coverage thickness of about 5 cm to form a physical barrier layer. The adsorption properties of the composite material are used to adsorb and fix the nitrogen, phosphorus and heavy metals released from the sediment, preventing them from further diffusing into the water.

[0048] Microbial agent application: After the aluminum-based composite material is covered, the immobilized microbial agent gel balls are evenly spread on its surface according to the planned application amount. The microbial agent will use the attachment sites provided by the aluminum-based composite material and its own metabolic activities to degrade and transform nitrogen and phosphorus adsorbed on the composite material and in the surrounding water and sediment, and to stabilize heavy metals.

[0049] Example 2

[0050] Prepare the ingredients:

[0051] Activated alumina powder: Activated alumina powder with a particle size of 200 mesh and a purity of 99.99% is selected as the main aluminum source for aluminum-based composite materials.

[0052] Bentonite: Sodium-based bentonite with a montmorillonite content of over 80% (in this example, the montmorillonite content of this Ayong product is 90%) is selected, and after grinding, it is passed through a 200-mesh sieve.

[0053] Diatomaceous earth: Select high-quality diatomaceous earth, calcine at 700℃ for 3 hours, and then crush it through a 150-mesh sieve.

[0054] Additives: Polyethylene glycol (PEG-4000) as a dispersant, sodium carboxymethyl cellulose (CMC) as a thickener and stabilizer.

[0055] Premix: Weigh each raw material according to the mass ratio of activated alumina powder: bentonite: diatomaceous earth = 6:3:2, put them into a high-speed mixer, add 1% of polyethylene glycol (PEG-4000) of the total mass of raw materials, and stir at 800 r / min for 20 minutes to make the raw materials fully mixed and uniform to obtain the premix.

[0056] Kneading: Slowly add an appropriate amount of deionized water to the premix, and at the same time add sodium carboxymethyl cellulose (CMC) at 0.5% of the total mass of the raw materials. Continue to stir and knead until a mud-like material with certain plasticity, uniform moisture and no obvious particle agglomeration is formed.

[0057] Shaping: The kneaded mud material is extruded into a cylindrical shape (2cm in diameter and 5cm in length) using an extruder, which facilitates subsequent application and covering operations.

[0058] Drying and sintering: The shaped material is placed in a ventilated drying oven and dried at 60°C for 12 hours to remove moisture. Then, the dried material is transferred to a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and sintered at this temperature for 3 hours to ensure tight bonding between the raw materials, improve the strength and stability of the composite material, and finally obtain the finished aluminum-based composite material.

[0059] Preparation of microbial agents

[0060] The ratio of nitrifying bacteria (Bio-74091, Nitrobacter Sp., purchased from Beijing Bio-74091 Bio-74091 Bio-74091 Bio-74091 Bio-74091 Bio-74091 Bio-74091 Bio-74091 Bio-74091 Bio-74092 ... 8 A mixed microbial culture was prepared by combining the microbial culture (CFU / mL). To improve the survival rate and stability of microorganisms in the lake sediment environment, the microbial culture was immobilized using a sodium alginate-calcium chloride encapsulation method. The specific operation was as follows: the microbial culture was mixed with a certain concentration (2%) sodium alginate solution at a volume ratio of 1:1, and then slowly dripped into a 2% calcium chloride solution using a syringe to form gel beads with a diameter of approximately 2.5 mm. These beads were then allowed to solidify in the calcium chloride solution for 1 hour, and then rinsed 2-3 times with physiological saline to obtain the immobilized microbial agent.

[0061] Application in in-situ cover of lake sediments

[0062] Preparation before deployment

[0063] Sediment pretreatment: The polluted sediment of the lake to be treated is simply leveled to remove large debris and garbage from the surface, making the sediment surface relatively flat and facilitating the uniform laying of subsequent covering materials.

[0064] Application Planning: Based on factors such as the lake's area, shape, and pollution level, the application areas and quantities of aluminum-based composite materials and microbial agents should be rationally planned. Generally, for heavily polluted areas, the application density should be appropriately increased. A preliminary estimate can be made based on a standard of 10 kg of aluminum-based composite materials and 200 microbial agent gel balls per square meter, which can then be fine-tuned according to the actual situation.

[0065] Deployment Operation

[0066] Aluminum-based composite material application: The prepared aluminum-based composite material is evenly applied to the surface of the lake sediment by manual throwing or mechanical spreading, ensuring a coverage thickness of about 5 cm to form a physical barrier layer. The adsorption properties of the composite material are used to adsorb and fix the nitrogen, phosphorus and heavy metals released from the sediment, preventing them from further diffusing into the water.

[0067] Microbial agent application: After the aluminum-based composite material is covered, the immobilized microbial agent gel balls are evenly spread on its surface according to the planned application amount. The microbial agent will use the attachment sites provided by the aluminum-based composite material and its own metabolic activities to degrade and transform nitrogen and phosphorus adsorbed on the composite material and in the surrounding water and sediment, and to stabilize heavy metals.

[0068] Experimental Example

[0069] A lake with typical eutrophication and a moderate size (approximately 5000 square meters) was selected as the experimental site, and the lake was divided into three areas:

[0070] Treatment area: In accordance with the technical solution described in Example 1, aluminum-based composite materials and microbial agents are applied to perform in-situ covering treatment of bottom sediment.

[0071] Control Zone 1 (material only): An equal amount of aluminum-based composite material was applied, but no microbial inoculant was applied. Other conditions were kept the same as in the treatment zone. This was used to compare and analyze the effects of the microbial inoculant.

[0072] Control Area 2 (Blank Control): No treatment is performed; the area remains in its natural state as a reference for the original pollution condition.

[0073] Detection indicators and methods

[0074] (I) Water body testing indicators and methods

[0075] Total nitrogen (TN):

[0076] Detection method: Alkaline potassium persulfate digestion-ultraviolet spectrophotometry was used. After collecting the water sample, alkaline potassium persulfate solution was added, and the sample was digested under high temperature and high pressure to convert nitrogen-containing compounds in the water sample into nitrates. After cooling, the absorbance was measured at wavelengths of 220 nm and 275 nm on an ultraviolet spectrophotometer, and the total nitrogen content was calculated according to the standard curve.

[0077] Testing frequency: Testing was conducted before treatment and at 1 week, 2 weeks, 1 month, 3 months and 6 months after treatment, with 3 parallel water samples collected each time and the average value taken.

[0078] Total phosphorus (TP):

[0079] Detection method: Ammonium molybdate spectrophotometry was used. After digestion, under acidic conditions, orthophosphate reacted with ammonium molybdate to form phosphomolybdic acid, which was then reduced by ascorbic acid to form a blue complex. The absorbance was measured at 700 nm on a spectrophotometer, and the total phosphorus content was obtained by referring to the standard curve.

[0080] Detection frequency: Same as the total nitrogen detection frequency, collect 3 parallel water samples each time and take the average value.

[0081] Ammonia nitrogen (NH3-N):

[0082] Detection method: Nessler's reagent spectrophotometry was used. Nessler's reagent was added to the water sample, reacting with ammonia nitrogen to form a light reddish-brown complex. The absorbance was measured at a wavelength of 420 nm, and the ammonia nitrogen content was calculated using a standard curve.

[0083] Detection frequency: Same as the total nitrogen detection frequency, collect 3 parallel water samples each time and take the average value.

[0084] Heavy metals [selected: copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb)]:

[0085] Detection method: Inductively coupled plasma mass spectrometry (ICP-MS) was used. After appropriate acidification pretreatment, the collected water samples were directly injected into the ICP-MS instrument to determine the content of each heavy metal element.

[0086] Testing frequency: Testing was conducted before treatment and at 1 month, 3 months and 6 months after treatment, with 3 parallel water samples collected each time and the average value taken.

[0087] (II) Sediment Testing Indicators and Methods

[0088] Total nitrogen (TN), total phosphorus (TP)

[0089] Detection methods: Total nitrogen content was determined by the Kjeldahl method. The sediment sample was heated and digested with concentrated sulfuric acid and a catalyst to convert organic nitrogen into ammonium nitrogen. The nitrogen content was then determined by distillation, titration and other steps. Total phosphorus was determined by the acid-dissolution-ammonium molybdate spectrophotometric method. The sediment sample was digested with an acid solution, and the subsequent operation was the same as the method for detecting total phosphorus in water.

[0090] Testing frequency: Sediment samples were collected before treatment and at 1 month, 3 months and 6 months after treatment for testing. Three parallel samples were collected each time, and a portion was taken for analysis after mixing.

[0091] Heavy metals, testing for copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb):

[0092] Detection methods: Microwave digestion-atomic absorption spectrometry (AAS) or inductively coupled plasma atomic emission spectrometry (ICP-AES) are used. First, the sediment sample is microwave-digested to convert the heavy metals in the sample into ionic states. Then, an appropriate method is selected based on the specific instrument, such as atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry, to determine the content of each heavy metal element.

[0093] Detection frequency: Same as the detection frequency of total nitrogen and total phosphorus in sediment. Three parallel samples are collected each time, and a portion is taken for analysis after mixing.

[0094] The organic matter content in the sediment is measured to characterize eutrophication.

[0095] The potassium dichromate titration method with external heating was employed. In the presence of concentrated sulfuric acid, excess potassium dichromate solution was used to oxidize the organic matter in the sediment. The remaining potassium dichromate was titrated with a standard ferrous sulfate solution, and the organic matter content was calculated based on the amount of ferrous sulfate consumed.

[0096] Detection frequency: Detection was carried out before treatment and at 1 month, 3 months and 6 months after treatment. Multiple measurements were taken at different locations each time and the average value was taken.

[0097] The test results are as follows:

[0098] Table 1 Water Body Testing Results

[0099]

[0100]

[0101] The data above show that the total nitrogen, total phosphorus, ammonia nitrogen, and heavy metal content in the treated area decreased significantly over time, and were significantly lower than those in control area 1 and control area 2 in each detection period (verified by analysis of variance, P<0.05). This indicates that the aluminum-based composite material and microbial agent provided by this invention have a significant effect on reducing pollutants in the water.

[0102] Table 2. Results of sediment testing

[0103]

[0104]

[0105] Sediment analysis data showed that the total nitrogen, total phosphorus, heavy metal, and organic matter content in the treated area decreased over time, indicating a reduction in nutrients and pollutants in the sediment and an improvement in the sediment environment. In contrast, the changes in control areas 1 and 2 were relatively small. This further demonstrates that the sediment covering material and microbial agent scheme of this invention can effectively act on the sediment, reduce the release of pollutants into the water body, and achieve the beneficial effect of mitigating lake eutrophication.

[0106] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lake bottom sediment in-situ controlled cover material, characterized in that, The mixture includes aluminum-based composite materials and microbial agents; the microbial agents contain nitrifying bacteria, Pseudomonas mendoza, and Bacillus subtilis; The ratio of nitrifying bacteria, Pseudomonas mendoza, and Bacillus subtilis in the microbial agent is 1:1.5-2.5:0.5-1.5; The aluminum-based composite material contains activated alumina powder; The preparation method of the in-situ controlled cover material for lake sediment includes the following steps: Activated alumina powder, bentonite, diatomaceous earth, polyethylene glycol and sodium carboxymethyl cellulose are mixed to obtain a mud-like material; The mud-like material is extruded, dried, and sintered to obtain an aluminum-based composite material. The bacterial suspensions of nitrifying bacteria, Pseudomonas mendoza, and Bacillus subtilis were mixed, fixed, and embedded to obtain a microbial inoculant. The diatomaceous earth is calcined at 600-800℃ for 2-3 hours before mixing; The mass ratio of activated alumina powder: bentonite: diatomaceous earth is 4.5–5.5: 2.5–3.5: 1.5–2.5; The amount of polyethylene glycol used is 0.5% to 2% of the total mass of the raw materials; The amount of sodium carboxymethyl cellulose used is 0.3% to 1% of the total mass of the raw materials; The sintering process is carried out at a temperature of 300–500°C for 2–3 hours. The extruded material particles have a diameter of 1-3 cm and a length of 4-6 cm. The dosage of the aluminum-based composite material is 5–20 kg / m³. 2 ; The fixation and embedding method is sodium alginate-calcium chloride embedding method, and the diameter of the material after fixation and embedding is 2-3 mm. The dosage of the microbial agent is 100-300 cells / m³. 2 .

2. The method for preparing the in-situ controlled cover material for lake sediment as described in claim 1, characterized in that, Includes the following steps: Activated alumina powder, bentonite, diatomaceous earth, polyethylene glycol and sodium carboxymethyl cellulose are mixed to obtain a mud-like material; The mud-like material is extruded, dried, and sintered to obtain an aluminum-based composite material. The bacterial suspensions of nitrifying bacteria, Pseudomonas mendoza, and Bacillus subtilis were mixed, fixed, and embedded to obtain a microbial inoculant. The diatomaceous earth is calcined at 600-800℃ for 2-3 hours before mixing; The mass ratio of activated alumina powder: bentonite: diatomaceous earth is 4.5–5.5: 2.5–3.5: 1.5–2.5; The amount of polyethylene glycol used is 0.5% to 2% of the total mass of the raw materials; The amount of sodium carboxymethyl cellulose used is 0.3% to 1% of the total mass of the raw materials; The sintering process is carried out at a temperature of 300–500°C for 2–3 hours. The extruded material particles have a diameter of 1-3 cm and a length of 4-6 cm. The dosage of the aluminum-based composite material is 5–20 kg / m³. 2 ; The fixation and embedding method is sodium alginate-calcium chloride embedding method, and the diameter of the material after fixation and embedding is 2-3 mm. The dosage of the microbial agent is 100-300 cells / m³. 2 .

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