Soil microorganism efficient water purification filter material and preparation process thereof

Abstract

The invention relates to a soil microorganism high-efficiency water purification filter material and a preparation process thereof, and aims to solve the problems of low removal efficiency, high cost, easiness in secondary pollution, insufficient affinity with soil microorganisms and the like of the existing microorganism filter material. The filter material is prepared by taking volcanic rock, activated carbon, bentonite and modified cellulose as main raw materials, combining the main raw materials according to a specific ratio, preparing porous particles by virtue of processes such as calcining, activating, mixing, granulating and sintering, and finally loading the porous particles by virtue of a microbial bacterial liquid. The product has a large specific surface area, good adsorption performance and high chemical stability, and can provide an excellent adhesion and growth environment for soil microorganisms. Experiments prove that the filter material can significantly improve the removal efficiency of pollutants such as COD, ammonia nitrogen and total phosphorus in sewage, and the filter material has the advantages of easily available raw materials, low cost and environmental friendliness, and is suitable for the fields of sewage treatment, ecological restoration and the like.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a high-efficiency soil microbial water purification filter material and its preparation process. Background Technology

[0002] With the rapid development of industrialization and urbanization, water pollution has become increasingly serious, and wastewater treatment has become an important task for environmental protection. Among the many wastewater treatment methods, utilizing the metabolic activity of microorganisms to decompose and remove pollutants from wastewater is an efficient, environmentally friendly, and economical approach. Microbial filter media, as a carrier for microbial attachment and growth, plays a crucial role in the effectiveness of wastewater treatment.

[0003] Currently, commercially available microbial filter media suffer from numerous problems. Some traditional filter media, such as quartz sand, while inexpensive, have a small specific surface area, limiting the amount of microorganisms that can adhere to them, resulting in low removal efficiency of pollutants from wastewater. On the other hand, some newer filter media, such as those made from synthetic materials, while having a large specific surface area and good adsorption performance, are expensive and have poor chemical stability, potentially releasing harmful substances into the water body during use, causing secondary pollution. Furthermore, most existing filter media lack sufficient affinity for soil microorganisms, failing to fully utilize the abundant microbial resources in the soil to improve water purification effects.

[0004] The existing background technologies are summarized as follows:

[0005] CN120464412A describes a method for preparing a saline-alkali land conditioner using mining solid waste (volcanic rock), rice husks, and seashells, with the core objective of soil improvement. Key processes include: oxalic acid activation and granulation of the volcanic rock solid waste; microbial fermentation and carbonization of the rice husks; and activation and chelation of the seashells with humic acid. Finally, the components are mixed with a binder (such as bentonite) and granulated. The aim is to adjust soil pH, replenish organic matter, and improve soil structure. Its material design and processes (such as oxalic acid activation) serve agricultural soil improvement. However, the technical solution in this document cannot be directly used for efficient water treatment because it lacks highly efficient adsorption components for pollutants in water and a dedicated water-purifying microbial community. This document does not address functional microbial loading: the mechanism of action of this conditioner is physicochemical modification and does not include any biodegradation function. It can only adsorb or fix salts and cannot completely eliminate organic pollutants in water. It focuses on ion exchange and slow nutrient release: such as using volcanic rock to adsorb sodium ions and using humic acid to chelate calcium and magnesium. It has a weak ability to cope with the instantaneous load shock of organic matter in water.

[0006] CN112079446A describes a microbial regulator for improving water transparency, consisting of a composite microbial agent and a porous suspended ceramsite carrier. The carrier preparation process involves using bentonite as the main raw material (60-75%), supplemented with sodium hydroxyethyl cellulose (1-3% as a binder) and wheat bran (10-15% as a pore-forming agent), followed by mixing, granulation, drying, high-temperature calcination (1000-1200℃), and ball milling to produce porous ceramsite. Microbial loading involves loading microorganisms (sulfur bacteria, nitrifying bacteria, etc.) onto the carrier after preparation through methods such as soaking. The document uses a single mineral material (bentonite): its function is limited, mainly providing physical attachment points with limited adsorption capacity. The carrier lacks the ability to pre-treat (adsorb) pollutants, resulting in a bottleneck in purification efficiency. It relies on ultra-high temperature calcination (1000-1200℃): this process is extremely energy-intensive, constituting a major part of the production cost, and may lead to sintering of some pores. Disadvantages include: the production process is not environmentally friendly, has high costs, and is difficult to promote on a large scale. The microbial loading method is post-loading: microorganisms are introduced after the carrier has fully formed. The microbial biofilm may be slower and shallower, and is easily lost under water scouring.

[0007] CN115896092A discloses a method for preparing composite microbial solidified particles, the core of which lies in the encapsulation and fixation of microorganisms using nano-magnetic iron oxide and sodium carboxymethyl cellulose (CMC). Key processes include: first, synthesizing nano-magnetic materials, then co-culturing them with microorganisms, followed by blending with zeolite, diatomaceous earth, etc., in a CMC solution, and finally chemically cross-linking and solidifying them using boric acid / calcium chloride solution to form gel-encapsulated particles. This method employs complex chemical cross-linking and encapsulation: involving nanomaterial synthesis, centrifugation, and multi-step chemical cross-linking, the process is cumbersome and the raw materials (nanomaterials, chemical cross-linking agents) are expensive. The production process is complex, has poor controllability, is costly, and the chemical cross-linking agent may potentially inhibit microbial activity. The dense gel encapsulation network severely hinders the transfer of pollutants and oxygen to the internal microorganisms, while metabolic products are also difficult to expel, leading to decreased reaction efficiency. This may result in low internal microbial activity and a slow overall purification speed. The gel strength is limited; under long-term operation and water erosion, the gel spheres are prone to wear and breakage, leading to microbial loss and a short service life. The carrier itself has poor durability, and the system operation is unstable.

[0008] Soil contains a vast array of microorganisms that play a crucial role in material cycling and pollutant degradation. Developing a highly efficient water purification filter medium with good affinity for soil microorganisms, and fully utilizing their advantages in wastewater treatment, would not only improve treatment efficiency and reduce costs but also minimize secondary pollution, holding significant practical importance. Summary of the Invention

[0009] The purpose of this invention is to provide a high-efficiency soil microbial water purification filter material and its preparation process, which solves the problems of low removal efficiency, high cost, secondary pollution, and insufficient affinity for soil microorganisms in existing microbial filter materials. Through a unique raw material formula and preparation process, the filter material has a large specific surface area, good adsorption performance, and high chemical stability. At the same time, it can combine well with soil microorganisms, give full play to the purification effect of soil microorganisms, and significantly improve the removal efficiency of pollutants in wastewater.

[0010] Raw material formulation: This water purification filter media uses volcanic rock, activated carbon, bentonite, and modified cellulose as its main raw materials. Volcanic rock has a rich porous structure and a large specific surface area, providing ample attachment sites for microorganisms. Its inherent minerals and trace elements also promote microbial growth and metabolism. Activated carbon also possesses a well-developed porous structure and strong adsorption properties, effectively adsorbing organic matter in wastewater, and its surface functional groups facilitate microbial fixation. Bentonite has good adsorption and ion exchange properties, adsorbing heavy metal ions and some organic matter in wastewater, while also enhancing the mechanical strength of the filter media. Modified cellulose is obtained by chemically modifying natural cellulose; it increases the hydrophilicity of the filter media, improves the adhesion of microorganisms to the filter media surface, and can also regulate the pore structure of the filter media to a certain extent. The mass fractions of each raw material are: volcanic rock 30-50 parts, activated carbon 20-30 parts, bentonite 10-20 parts, and modified cellulose 5-15 parts.

[0011] A preparation process for a high-efficiency soil microbial water purification filter material, using volcanic rock, activated carbon, bentonite, and modified cellulose as the main raw materials, with the following mass proportions: volcanic rock 30-50 parts, activated carbon 20-30 parts, bentonite 10-20 parts, and modified cellulose 5-15 parts; the preparation process is as follows:

[0012] S1) Crush volcanic rock into particles with a diameter of 0.1-0.5 mm, and calcine it in a high-temperature furnace at 800-1000℃ for 2-4 hours to further expand its pore structure and increase its specific surface area;

[0013] S2) Activate the activated carbon using a physical activation method. At a high temperature of 900-1100℃, steam is introduced for 1-3 hours to increase the number of pores and active sites on the surface of the activated carbon.

[0014] S3) The bentonite is purified to remove impurities and then mixed with an appropriate amount of water to make bentonite slurry.

[0015] S4) Dissolve the modified cellulose in an appropriate amount of solvent to prepare a solution of a certain concentration;

[0016] S5) Add the calcined volcanic rock particles and activated carbon particles to the bentonite slurry, stir evenly, then add the modified cellulose solution and continue stirring to fully mix the raw materials.

[0017] S6) The mixture is granulated into particles with a diameter of 3-5 mm using a granulator;

[0018] S7) Place the obtained granules in a drying oven and dry them to constant weight at 100-120℃. Then place them in a high-temperature furnace and sinter them at 500-700℃ for 2-3 hours to give them sufficient mechanical strength.

[0019] S8) The sintered filter media particles are soaked in a bacterial solution containing a variety of soil microorganisms and cultured at 30-35℃ for 24-48 hours with shaking, so that the microorganisms can fully adhere to the surface and pores of the filter media, thus obtaining a high-efficiency soil microbial water purification filter media.

[0020] Preferably, in step S1): the volcanic rock is crushed into particles with a particle size of 0.1-0.5 mm, placed in a high-temperature furnace and calcined at 800-1000℃ for 2-4 hours. Calcination at 800-1000℃ increases the porosity of the volcanic rock from 20%-30% to 30%-40%, and reduces the average pore size from micrometer to nanometer.

[0021] Preferably, in step S2), the activated carbon is activated using a physical activation method. At a high temperature of 900-1100℃, steam is introduced for 1-3 hours to increase the number of pores and active sites on the activated carbon surface. Specifically, the specific surface area increases from 200-400 m² / g for unactivated carbon to 800-1500 m² / g after activation; the number of pores changes from 0.1-0.3 cm³ / g to 0.5-1.2 cm³ / g; micropores smaller than 2 nm increase significantly, and mesopores between 2-50 nm increase moderately; active sites mainly form oxygen-containing functional groups, such as carboxyl, hydroxyl, and carbonyl groups; more active sites are formed at irregularly arranged areas on the surface, with a site density reaching 10. 19 -10 20 Units / m²

[0022] Preferably, in step S3), the bentonite is purified to remove impurities, specifically as follows: S31) Crushing and grinding: The raw ore is crushed to below 200 mesh (0.074 mm); S32) Wet scrubbing: Water is added and stirred (solid content 20-30%), and scrubbed for 10-30 minutes; S33) Hydrocyclone separation: Quartz and feldspar are separated using a hydrocyclone with a diameter of 50-100 mm; S34) Sedimentation classification: The concentration and time are controlled to suspend montmorillonite and allow impurities to settle; S35) Dehydration and drying: Vacuum filtration or pressure filtration is performed to dry to a moisture content of 8-12%.

[0023] Preferably, in step S3), the main impurities removed include: quartz (SiO2): reduced to below 5-10%; feldspar: reduced to below 3-5%; carbonate: reduced to below 1-2% by acid washing; iron oxide: reduced to below 0.5-1% by magnetic separation or acid washing; and organic matter: reduced to below 0.3-0.5% by oxidation treatment.

[0024] Preferably, in step S3), the bentonite is then mixed with an appropriate amount of water to form bentonite slurry. The conventional formulation is as follows: solid content: 20-30% by mass, that is, 233-400mL of water is added for every 100g of bentonite. High-quality high-viscosity slurry: solid content: 15-20%, that is, 400-567mL of water is added for every 100g of bentonite.

[0025] Preferably, in step S4), the modified cellulose includes CMC, HPMC, CA, cellulose-g-polyacrylamide, and oxidized cellulose.

[0026] Preferably, step S4) uses carboxymethyl cellulose (CMC), solvent: distilled water, concentration range: 1-5% (mass-volume ratio), slowly dispersed in water and stirred to avoid clumping, which can form a viscous solution.

[0027] Preferably, step S4)

[0028] The carboxymethyl chemical modification process is as follows: Modified cellulose is usually modified through chemical modification methods such as carboxymethylation, and the specific steps include:

[0029] Alkali treatment: Natural cellulose is soaked in an alkaline solution to make the hydroxyl groups on its cellulose molecular chains more active.

[0030] Etherification reaction: Add carboxymethylating agents, such as chloroacetic acid and sodium hydroxide, and carry out the etherification reaction under alkaline conditions to introduce carboxymethyl groups (-O-COCH3) onto the cellulose molecular chain.

[0031] Neutralization and washing: After the reaction is complete, the mixture is neutralized and washed to remove unreacted reagents and impurities, yielding the modified carboxymethyl cellulose.

[0032] Drying and pulverizing: The neutralized product is dried to remove moisture, and then pulverized into the required particle size.

[0033] Preferably, in step S7), the obtained granules are placed in a drying oven and dried to constant weight at 100-120°C, and then sintered in a high-temperature furnace at 500-700°C for 2-3 hours to give them sufficient mechanical strength; specifically as follows:

[0034] S71) Drying and sintering are as follows:

[0035] During the drying process, free water and some bound water in the particles are removed, the internal moisture of the particles evaporates, forming a preliminary porous structure, and the binders such as modified cellulose begin to soften and cross-link, initially binding the various components together.

[0036] S72) The sintering process is as follows:

[0037] Modified cellulose is completely carbonized or burned away, leaving a porous framework; clay minerals such as bentonite undergo dehydration, phase transformation and partial melting, and neck connections are formed between adjacent particles; the structure becomes dense, the pore structure is rearranged, some small pores disappear and large pores are retained;

[0038] After sintering, the compressive strength reaches 5-20 MPa, and the specific surface area reaches 100-300 m² / g. After sintering, a multi-level porous structure is formed, with micropores, mesopores, and macropores coexisting. The total pore volume reaches 0.3-0.8 cm³ / g, and the pore size distribution is mainly concentrated in 2-50 nm, which is suitable for microbial attachment and material transport.

[0039] Preferably, in step S8), the soil microorganisms include Bacillus, Pseudomonas, and nitrifying bacteria, and the bacterial concentration is controlled at 10. 8 Up to 10 10 The CFU / mL level was between 10 CFU / mL and the microbial attachment level was between 10 CFU / mL and 10 CFU / mL. 7 Up to 10 9 The amount of adhesion between CFUs is beneficial for the rapid formation of biofilm.

[0040] A high-efficiency soil microbial water purification filter material is prepared according to the preparation process of the aforementioned high-efficiency soil microbial water purification filter material.

[0041] The filter media of this invention possesses a rich porous structure and a large specific surface area, providing ample space for microorganisms to attach and grow, enabling them to multiply rapidly and significantly improving the removal capacity of pollutants such as chemical oxygen demand (COD), ammonia nitrogen, and total phosphorus from wastewater. Experimental verification shows that, under the same conditions, wastewater treatment systems using the filter media of this invention achieve a 25-35% higher COD removal rate, a 20-30% higher ammonia nitrogen removal rate, and a 15-25% higher total phosphorus removal rate compared to traditional microbial filter media.

[0042] Low cost: The main raw materials of the filter media of this invention, such as volcanic rock, activated carbon, and bentonite, are all common and relatively inexpensive materials with wide availability, which reduces the preparation cost of the filter media and makes it economically advantageous in large-scale applications.

[0043] Good chemical stability: Through specific preparation processes and raw material formulations, the filter media has good chemical stability, making it less likely to release harmful substances into water bodies during wastewater treatment, thus avoiding secondary pollution and meeting environmental protection requirements.

[0044] Strong affinity with soil microorganisms: The raw material composition and surface characteristics of the filter media give it a good affinity with soil microorganisms, which can quickly attract soil microorganisms to attach and grow, form a stable microbial community, give full play to the purification function of soil microorganisms, and improve the efficiency and stability of sewage treatment. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a scanning electron microscope image of the microbial filter media of the present invention.

[0047] Figure 2 This is a comparison curve showing the change of COD removal rate over time when using the microbial filter media of this invention and traditional microbial filter media to treat domestic sewage.

[0048] Figure 3 This is a comparison curve showing the change of ammonia nitrogen removal rate over time when using the microbial filter media of this invention and traditional microbial filter media to treat domestic sewage.

[0049] Figure 4 This is a flowchart illustrating the preparation process of the present invention.

[0050] Figure 5 This is a comparison chart of COD removal rate tests for the present invention and a comparative example.

[0051] Figure 6 This is a comparison chart of the ammonia nitrogen removal rates of the present invention and the comparative example.

[0052] Figure 7 This is a comparison chart of the total phosphorus removal rates of the present invention and the comparative example. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] The purpose of this invention is to provide a high-efficiency soil microbial water purification filter material and its preparation process, which solves the problems of low removal efficiency, high cost, secondary pollution, and insufficient affinity for soil microorganisms in existing microbial filter materials. Through a unique raw material formula and preparation process, the filter material has a large specific surface area, good adsorption performance, and high chemical stability. At the same time, it can combine well with soil microorganisms, give full play to the purification effect of soil microorganisms, and significantly improve the removal efficiency of pollutants in wastewater.

[0056] Raw material formulation: This water purification filter media uses volcanic rock, activated carbon, bentonite, and modified cellulose as its main raw materials. Volcanic rock has a rich porous structure and a large specific surface area, providing ample attachment sites for microorganisms. Its inherent minerals and trace elements also promote microbial growth and metabolism. Activated carbon also possesses a well-developed porous structure and strong adsorption properties, effectively adsorbing organic matter in wastewater, and its surface functional groups facilitate microbial fixation. Bentonite has good adsorption and ion exchange properties, adsorbing heavy metal ions and some organic matter in wastewater, while also enhancing the mechanical strength of the filter media. Modified cellulose is obtained by chemically modifying natural cellulose; it increases the hydrophilicity of the filter media, improves the adhesion of microorganisms to the filter media surface, and can also regulate the pore structure of the filter media to a certain extent.

[0057] The mass fractions of each raw material are as follows: volcanic rock 30-50 parts, activated carbon 20-30 parts, bentonite 10-20 parts, and modified cellulose 5-15 parts.

[0058] The preparation process is as follows: Figure 4 As shown:

[0059] S1) Crush volcanic rock into particles with a diameter of 0.1-0.5 mm, and calcine them in a high-temperature furnace at 800-1000℃ for 2-4 hours to further expand their pore structure and increase their specific surface area.

[0060] S2) Activate the activated carbon using a physical activation method. At a high temperature of 900-1100℃, steam is introduced for 1-3 hours to increase the number of pores and active sites on the surface of the activated carbon.

[0061] S3) The bentonite is purified to remove impurities and then mixed with an appropriate amount of water to make bentonite slurry.

[0062] S4) Dissolve the modified cellulose in an appropriate amount of solvent to prepare a solution of a certain concentration.

[0063] S5) Add the calcined volcanic rock particles and activated carbon particles to the bentonite slurry, stir evenly, then add the modified cellulose solution and continue stirring to ensure that all raw materials are fully mixed.

[0064] S6) The mixture is made into granules with a particle size of 3-5mm by a granulator.

[0065] S7) Place the obtained granules in a drying oven and dry them to constant weight at 100-120℃. Then place them in a high-temperature furnace and sinter them at 500-700℃ for 2-3 hours to give them sufficient mechanical strength.

[0066] S8) The sintered filter media particles are soaked in a bacterial solution containing a variety of soil microorganisms (such as Bacillus, Pseudomonas, nitrifying bacteria, etc.) and cultured at 30-35℃ with shaking for 24-48 hours to allow the microorganisms to fully adhere to the surface and pores of the filter media, thus obtaining a high-efficiency soil microbial water purification filter media.

[0067] In step S1): the volcanic rock is crushed into particles with a particle size of 0.1-0.5 mm and placed in a high-temperature furnace and calcined at 800-1000℃ for 2-4 hours to further expand its pore structure and increase its specific surface area.

[0068] Regarding the effect of high-temperature calcination on the pore structure of volcanic rocks, generally speaking, high-temperature calcination reduces the micron-sized pores and increases the nano-sized pores. Calcination at 800-1000℃ can increase the porosity of volcanic rocks from approximately 20%-30% to approximately 30%-40%, and the average pore size may decrease from a few micrometers to several hundred nanometers. Specific values ​​will vary depending on the type of volcanic rock, its initial structure, and other factors.

[0069] In step S2), the activated carbon is activated using a physical activation method. Steam is introduced at a high temperature of 900-1100℃ for 1-3 hours to increase the number of pores and active sites on the activated carbon surface. The changes in specific surface area, number of pores, and active sites are as follows:

[0070] Increase in specific surface area:

[0071] Unactivated carbon material: approximately 200-400 m² / g

[0072] After activation: typically reaching 800-1500 m² / g

[0073] Increase: 3-5 times, depending on raw materials and activation conditions

[0074] Changes in the number of pores

[0075] Total pore volume: increased from 0.1-0.3 cm³ / g to 0.5-1.2 cm³ / g

[0076] Micropores (<2nm): The increase is most significant, and they are the main sites of adsorption.

[0077] Mesopores (2-50nm): A moderate increase is beneficial for the diffusion of macromolecules.

[0078] Changes in active sites

[0079] It mainly forms oxygen-containing functional groups, such as carboxyl, hydroxyl, and carbonyl groups.

[0080] More active sites are formed at the irregular arrangement of surface atoms.

[0081] Site density: up to 10 19 -10 20 Units / m²

[0082] These sites enhance the adsorption capacity for polar molecules.

[0083] In step S3), the bentonite is purified to remove impurities, and then mixed with an appropriate amount of water to make bentonite slurry.

[0084] First, the bentonite is purified to remove impurities, as detailed below:

[0085] S31). Crushing and grinding: Crushing the raw ore to below 200 mesh (0.074 mm).

[0086] S32). Wet scrubbing: Add water and stir (solid content 20-30%), scrub for 10-30 minutes.

[0087] S33). Hydrocyclone separation: Using a hydrocyclone with a diameter of 50-100 mm, quartz and feldspar are separated.

[0088] S34). Sedimentation classification: Controlling concentration and time to suspend montmorillonite and allow impurities to settle.

[0089] S35). Dehydration and drying: Vacuum filtration or pressure filtration, drying to a moisture content of 8-12%.

[0090] The main impurities removed include:

[0091] Quartz (SiO2): Reduced to below 5-10%

[0092] Feldspar: Reduced to below 3-5%

[0093] Carbonates: Reduced to below 1-2% by acid washing.

[0094] Iron oxide: Reduced to below 0.5-1% by magnetic separation or acid washing.

[0095] Organic matter: Reduced to below 0.3-0.5% through oxidation treatment.

[0096] II. Purity control indicators, i.e., the levels that should be achieved after purification, are as follows:

[0097] Third, mix it with an appropriate amount of water to make bentonite slurry. The standard mixing ratio is as follows:

[0098] Solid content: 20-30% (mass fraction)

[0099] That is, add 233-400mL of water to every 100g of bentonite.

[0100] High-quality, high-viscosity drilling mud: solids content 15-20%

[0101] That is, add 400-567 mL of water to every 100 g of bentonite.

[0102] In step S4), the modified cellulose is dissolved in an appropriate amount of solvent to prepare a solution of a certain concentration, as detailed below:

[0103] In step S4), modified cellulose is obtained by chemically modifying natural cellulose. Although natural cellulose is widely available, it has some drawbacks: poor water solubility, difficulty in dispersing in many solvents, low thermal stability, easy decomposition, and sometimes unsatisfactory mechanical properties. After modification, these drawbacks are improved, and new functions can be acquired, such as increasing water solubility or dispersibility in organic solvents, improving thermal stability and mechanical strength, and introducing special functional groups, such as the ability to adsorb heavy metals. The modified cellulose acts as a binder and bridge in material mixtures: its molecular chains contain both hydrophilic and hydrophobic groups, which can connect material components with different properties, making the entire system more homogeneous and stable, and preventing stratification or precipitation of components. Examples of modified cellulose are shown below:

[0104]

[0105] In this embodiment, carboxymethyl cellulose (CMC) can be used. The solvent is distilled water, and the concentration range is 1-5% (by mass and volume). The solution is slowly dispersed in water and stirred to avoid clumping, thus forming a viscous solution.

[0106] The carboxymethyl chemical modification process is as follows: Modified cellulose is usually modified through chemical modification methods such as carboxymethylation, and the specific steps include:

[0107] Alkali treatment: Natural cellulose is soaked in an alkaline solution to make the hydroxyl groups on its cellulose molecular chains more active.

[0108] Etherification reaction: Add carboxymethylating agents, such as chloroacetic acid and sodium hydroxide, and carry out the etherification reaction under alkaline conditions to introduce carboxymethyl groups (-O-COCH3) onto the cellulose molecular chain.

[0109] Neutralization and washing: After the reaction is complete, the mixture is neutralized and washed to remove unreacted reagents and impurities, yielding the modified carboxymethyl cellulose.

[0110] Drying and pulverizing: The neutralized product is dried to remove moisture, and then pulverized into the required particle size.

[0111] The effects of modified cellulose are as follows:

[0112] 1) Increased hydrophilicity: The introduction of carboxymethyl groups makes cellulose molecules more hydrophilic, improving their solubility and dispersibility in water.

[0113] 2) Improved binding capacity: Modified cellulose is easier to bind with other components such as volcanic rock and activated carbon, enhancing the structural stability of the filter media.

[0114] 3) Enhanced adsorption performance: The modified cellulose acts as a binder in the filter media, helping to form a uniform pore structure and improving the adsorption and microbial adhesion capabilities of the filter media.

[0115] 4) Role in material mixing: Binding effect: Modified cellulose acts as a binder, helping volcanic rock, activated carbon, and bentonite particles to adhere together, forming a homogeneous mixture. Structural stability: During mixing, the hydrophilicity and high viscosity of modified cellulose help maintain the viscosity of the mixture, preventing particle separation and ensuring smooth granulation.

[0116] 5) Functions after drying and roasting:

[0117] Structure maintenance: During the drying process, modified cellulose helps maintain the shape and structure of the particles and prevents them from breaking.

[0118] High-temperature treatment: During the calcination process, the modified cellulose may be partially decomposed or carbonized, but it still retains the characteristics of its modified part, continuing to provide hydrophilicity and structural stability, ensuring that the filter media is not easily broken during use and maintaining efficient adsorption and microbial adhesion capabilities.

[0119] Modified cellulose increases hydrophilicity and improves its binding ability with other components through chemical modification. It also plays a role in bonding and structural stabilization during the preparation process, ultimately improving the performance and service life of the filter media.

[0120] In step S7), the obtained granules are placed in a drying oven and dried at 100-120°C to constant weight, and then placed in a high-temperature furnace and sintered at 500-700°C for 2-3 hours to give them sufficient mechanical strength.

[0121] I. Drying and sintering are detailed as follows:

[0122] Drying process (100-120℃)

[0123] Physical changes: Primarily removes free water and some bound water from the particles.

[0124] Weight loss: Typically 10-25% weight loss until a constant weight is achieved.

[0125] Structural changes: Water evaporates from the inside of the particles, forming a preliminary porous structure.

[0126] Initial curing: The binder, such as modified cellulose, begins to soften and cross-link, initially bonding the various components together.

[0127] Sintering process (500-700℃)

[0128] Organic combustion: Modified cellulose is completely carbonized or burned, leaving behind a porous framework.

[0129] Inorganic reactions: Bentonite and other clay minerals undergo dehydration, phase transformation, and partial melting.

[0130] Particle fusion: A neck connection is formed between adjacent particles, similar to a "welding" effect.

[0131] Structural densification: The pore structure is rearranged, some small pores disappear, and large pores are retained.

[0132] II. Impact on carrier performance indicators

[0133] 1. Mechanical strength

[0134] After drying: Low strength, mainly relies on adhesive bonding, easily broken.

[0135] After sintering: the strength is significantly improved, and the compressive strength can reach 5-20 MPa.

[0136] Influencing factors: The higher the bentonite content and the higher the sintering temperature, the greater the strength is usually.

[0137] 2. Specific surface area

[0138] After drying: The specific surface area is moderate, mainly derived from the raw material itself.

[0139] After sintering: the specific surface area increases significantly, typically reaching 100-300 m² / g.

[0140] Reason: The burning of cellulose leaves behind a large number of micropores, and volcanic rocks and bentonite also produce new pores at high temperatures.

[0141] 3. Pore structure

[0142] After drying: mainly composed of large pores between raw material particles.

[0143] After sintering: a multi-level porous structure is formed, with micropores, mesopores, and macropores coexisting.

[0144] Total pore volume: up to 0.3-0.8 cm³ / g

[0145] Pore ​​size distribution: mainly concentrated in 2-50 nm, suitable for microbial attachment and material transport.

[0146] III. Relationship between performance indicators and raw materials and processes

[0147] 1. Mechanical strength

[0148] Raw material relationship: Bentonite is the main binder phase, and the higher the content, the better the strength. Volcanic rock has high hardness but is brittle, so it needs to be added in appropriate amounts.

[0149] Process relationship: The higher the sintering temperature and the longer the time, the more fully the particles are integrated and the higher the strength. However, excessively high temperature will lead to over-densification and reduce the specific surface area.

[0150] 2. Specific surface area and pore structure

[0151] Raw material relationship: Activated carbon and modified cellulose are the main pore-forming agents.

[0152] Activated carbon itself is porous, and cellulose leaves pores after combustion. Bentonite and volcanic rock provide skeletal support.

[0153] Process relationship: Sintering temperature is the key. 500-600℃ can retain more pores, while exceeding 700℃ may cause pore collapse and a decrease in specific surface area.

[0154] 3. Microbial affinity

[0155] Raw material relationship: Modified cellulose and bentonite provide surface chemical sites, while the high specific surface area of ​​activated carbon provides adhesion space.

[0156] Process relationship: The multi-level pores formed by the appropriate sintering temperature protect microorganisms from water erosion and ensure the transport of nutrients.

[0157] In summary, these two processes are key steps in integrating the characteristics of the four raw materials and transforming them into the final carrier performance.

[0158] In step S8), the sintered filter media particles are soaked in a bacterial solution containing various soil microorganisms (such as Bacillus, Pseudomonas, nitrifying bacteria, etc.) and cultured at 30-35℃ with shaking for 24-48 hours to allow the microorganisms to fully adhere to the surface and pores of the filter media, thus obtaining a high-efficiency soil microbial water purification filter media.

[0159] The bacterial concentration is usually controlled at 10. 8 Up to 10 10 The CFU / mL range indicates that the amount of microorganisms attached is typically between 10 per gram of filter media. 7 Up to 10 9 Between CFUs.

[0160] High-efficiency adhesion: 10 7 - 10 9 The amount of CFU / g attached is beneficial for the rapid formation of biofilm.

[0161] Structural advantages: Microorganisms not only attach to the surface but also penetrate deep into the pores, and this three-dimensional distribution improves the resistance to water erosion.

[0162] Functional guarantee: A high amount of adhering microorganisms means more functional microorganisms, which can more effectively degrade pollutants and improve water purification effect.

[0163] As attached Figure 1The image shown is a scanning electron microscope image of the microbial filter media of the present invention, which shows the microscopic pore structure of the filter media. It can be seen that the pores are abundant and uniformly distributed, which is conducive to the attachment of microorganisms and the adsorption of pollutants.

[0164] Appendix Figure 1 The microscopic pore structure reveals the following: Overall morphology: irregular granular shape with a rough surface; Pore type: exhibiting a multi-level pore structure.

[0165] Macropores: 50-200 micrometers in diameter (pores visible to the naked eye)

[0166] Mesopores: 2-50 micrometers in diameter (distributed on the particle surface)

[0167] Micropores: 2 nanometers to 2 micrometers in diameter (tiny pores visible under high magnification).

[0168] Labeled data: Total porosity: 55%

[0169] Average pore size: 15 micrometers

[0170] Specific surface area: 180 m² / g.

[0171] Figure 2 The graph shows a comparison of COD removal rate over time when using the microbial filter media of this invention and traditional microbial filter media to treat domestic sewage. The filter media of this invention is represented by a gray broken line, while the traditional quartz sand filter media is represented by a black broken line. Figure 2 It can be clearly seen that the filter media of the present invention has a significantly better COD removal effect than traditional filter media. It can more effectively reduce the COD content in wastewater within the same time period. The COD removal rate of the filter media of the present invention is about 35% higher than that of traditional filter media.

[0172] Figure 3 The graph shows a comparison of ammonia nitrogen removal rates over time when using the microbial filter media of this invention and traditional microbial filter media to treat domestic sewage. The filter media of this invention is represented by a gray line, while the traditional quartz sand filter media is represented by a black line. This indicates that the filter media of this invention has a stronger ammonia nitrogen removal capacity and can reduce the ammonia nitrogen content in sewage to a lower level more quickly. The removal rate of the filter media of this invention increases more rapidly after 12 hours. The final result is that the ammonia nitrogen removal rate of the filter media of this invention is about 53% higher than that of the traditional filter media.

[0173] The beneficial effects of this invention are:

[0174] 1) The filter media of this invention possesses a rich pore structure and a large specific surface area, providing ample space for microorganisms to attach and grow, enabling them to multiply rapidly and thus significantly improving the removal capacity of pollutants such as chemical oxygen demand (COD), ammonia nitrogen, and total phosphorus from wastewater. Experimental verification shows that, under the same conditions, wastewater treatment systems using the filter media of this invention achieve a 25-35% higher COD removal rate, a 20-30% higher ammonia nitrogen removal rate, and a 15-25% higher total phosphorus removal rate compared to traditional microbial filter media.

[0175] 2) Compared with common microbial filter media on the market, such as traditional quartz sand, the specific surface area and microbial adhesion of the filter media in this application are compared with those of traditional quartz sand filter media as follows:

[0176] Comparison table of filter media performance

[0177]

[0178] The results above show the advantages in specific surface area: the filter media of this application provides a larger specific surface area and adsorption capacity. Traditional quartz sand has a smooth surface, leaving no place for microorganisms to attach. The filter media of this application has abundant pores and folds, which can accommodate more microorganisms. The advantage in microbial attachment: directly reflecting the quantity and activity of the biofilm; the attachment amount of the filter media of this application is 1-2 orders of magnitude higher, meaning stronger pollutant degradation ability and higher purification efficiency. Overall effect: the filter media of this invention has a higher microbial density and a faster reaction rate.

[0179] 3) Compared to some novel filter media, such as those made of synthetic materials, the filter media of this invention, while having a large specific surface area and good adsorption performance, is also expensive and has poor chemical stability, potentially releasing harmful substances into the water during use and causing secondary pollution. The specific surface area, adsorption capacity, and other indicators of the filter media of this application are compared with those of some novel filter media as follows:

[0180] Comparison table of performance of different filter media

[0181]

[0182] The results above show that: 1. Adsorption performance comparison: While the specific surface area and adsorption capacity of synthetic filter media are similar, our filter media achieves complete removal of pollutants through biodegradation rather than simple physical adsorption, rather than merely transfer. This eliminates the need for regeneration and results in lower long-term operating costs. 2. Cost-effectiveness analysis: The cost of the filter media of this invention is only 1 / 5 to 1 / 20 of that of synthetic filter media, with a longer service life and a significant overall cost advantage. Although synthetic filter media has a strong initial adsorption capacity, it is easily saturated, requiring frequent replacement or regeneration, increasing operating costs. 3. Chemical stability comparison: The filter media of this invention is sintered at high temperature, resulting in a stable structure that can be used across a wide pH range without the risk of secondary pollution. Synthetic filter media is prone to decomposition under extreme conditions, potentially releasing microplastics or other harmful substances.

[0183] Example 1

[0184] 1. Raw material preparation: Take 30g volcanic rock, 25g activated carbon, 15g bentonite, and 10g modified cellulose.

[0185] 2. Volcanic rock treatment: Crush the volcanic rock into particles with a diameter of 0.1 mm, and calcine it in a high-temperature furnace at 800°C for 4 hours.

[0186] 3. Activated carbon activation: Activate the activated carbon at a high temperature of 900℃ by passing steam through it for 3 hours.

[0187] 4. Bentonite treatment: After purifying the bentonite, it is mixed with an appropriate amount of water to make bentonite slurry.

[0188] 5. Dissolving modified cellulose: Dissolve the modified cellulose in an appropriate amount of solvent to prepare a 5% solution.

[0189] 6. Mixing and granulation: Add the calcined volcanic rock particles and activated carbon particles to the bentonite slurry, stir evenly, then add the modified cellulose solution and continue stirring. Then, use a granulator to granulate the mixture into particles with a diameter of 3mm.

[0190] 7. Drying and sintering: Place the obtained granules in a drying oven and dry them at 100°C to constant weight, then place them in a high-temperature furnace and sinter at 500°C for 3 hours.

[0191] 8. Microbial loading: The sintered filter media particles were soaked in a bacterial solution containing Bacillus, Pseudomonas, and nitrifying bacteria. The concentration of each bacterial species in the bacterial solution was 1×10^8 CFU / mL. The solution was shaken and cultured at 30℃ for 48 hours to obtain microbial filter media.

[0192] Example 2

[0193] 1. Raw material preparation: Take 40g volcanic rock, 20g activated carbon, 10g bentonite, and 15g modified cellulose.

[0194] 2. Volcanic rock treatment: Crush the volcanic rock into particles with a diameter of 0.3 mm and calcine it at 900℃ for 3 hours.

[0195] 3. Activated carbon activation: Activate the activated carbon by passing steam through it at a high temperature of 1000℃ for 2 hours.

[0196] 4. The bentonite treatment and subsequent steps are the same as in Example 1, and the particles with a diameter of 4 mm are prepared. After drying at 110°C, they are sintered at 600°C for 2.5 hours, and finally loaded with microorganisms by shaking culture at 32°C for 36 hours.

[0197] The filter media of this invention has a rich pore structure and a large specific surface area, providing ample space for microorganisms to attach and grow: 1. Pore structure

[0198] Total pore volume: 0.3 - 0.8 cm³ / g

[0199] Porosity: 40% - 65%

[0200] Pore ​​size distribution: mainly concentrated in the range of 2-50 nm, forming a hierarchical pore structure.

[0201] 2. Specific surface area

[0202] Numerical range: 100 - 300 m² / g

[0203] Note: This value represents the nitrogen adsorption surface area measured by the BET method, which is significantly higher than that of ordinary quartz sand filter media (typically <1 m² / g).

[0204] 3. Microbial attachment amount

[0205] Numerical range: 10 7 - 10 9 CFU / g filter media

[0206] Note: This represents the number of functional microorganisms that can stably colonize the surface and pores of the filter media.

[0207] This invention, through a specific preparation process and raw material formulation, enables the filter media to possess excellent chemical stability, making it less likely to release harmful substances into water bodies during wastewater treatment, thus avoiding secondary pollution and meeting environmental protection requirements. The specific reasons are as follows:

[0208] 1. The chemical inertness of the raw materials themselves

[0209] Volcanic rock: Its main components are silicon dioxide and aluminum oxide, which are chemically very stable substances that do not easily react in acidic or alkaline environments.

[0210] Bentonite: After high-temperature sintering, its clay mineral structure undergoes an irreversible phase transformation, forming a more stable crystal structure, and it is no longer as easy to absorb water, swell, or disperse as the original clay.

[0211] 2. The role of high-temperature sintering

[0212] At high temperatures of 500-700℃, the organic matter (modified cellulose) in the raw materials will be completely burned off, preventing the organic components from dissolving in water. The high temperature promotes the chemical bonding between inorganic mineral particles, forming a dense structure similar to ceramics, which improves the overall resistance to chemical erosion.

[0213] 3. Structural densification effect

[0214] During sintering, strong neck connections are formed between the particles. This structure greatly reduces the penetration of water and contaminant molecules into the material's interior, minimizing the chance of chemical reactions with the material.

[0215] 4. Optimization of surface properties

[0216] High-temperature treatment alters the chemical properties of the material surface, reducing the number of reactive sites and enabling the filter media to exhibit good resistance to various chemicals.

[0217] Comparative Example

[0218] Commercially available ordinary microbial filter media was used as a comparative example. The main component of this filter media is quartz sand, which has not undergone special pore structure optimization and microbial loading treatment.

[0219] Performance testing

[0220] 1. COD Removal Rate Test: The microbial filter media prepared in Examples 1 and 2, and the commercially available filter media of the comparative example, were placed in biological filter beds of the same specifications. The same quality and volume of domestic sewage were added to each filter bed, with an initial COD concentration of 350 mg / L. The filter beds were operated under conditions of a hydraulic retention time of 10 hours, a temperature of 28°C, and a pH of 7.0. The COD concentration of the effluent from the filter beds was measured periodically, and the COD removal rate was calculated. The results are as follows: Figure 5 As shown, the data details are shown in Table 1.

[0221] Table 1. COD Removal Rate Test Results

[0222]

[0223] 2. Ammonia Nitrogen Removal Rate Test: Under the same conditions described above, the ammonia nitrogen removal rate in the wastewater was tested. The initial ammonia nitrogen concentration in the wastewater was 50 mg / L. The results are as follows: Figure 6 As shown, the detailed results of the data are shown in Table 2.

[0224] Table 2 Ammonia nitrogen removal rate test results

[0225]

[0226] 3. Total Phosphorus Removal Rate Test: Under the same conditions as above, the total phosphorus removal rate in the wastewater was tested. The initial total phosphorus concentration in the wastewater was 10 mg / L. The results are as follows: Figure 7 As shown, the detailed results of the data are shown in Table 3.

[0227] Table 3 Total phosphorus removal rate test results

[0228]

[0229] 4. Chemical stability test: The three filter media were immersed in simulated wastewater, and the release of harmful substances in the immersion solution was detected at different time points. After long-term testing, no harmful substances were detected in the filter media of Example 1 and Example 2, while a small amount of heavy metal ions were detected in the filter media of the comparative example after long-term immersion.

[0230] The performance test results of the above embodiments and comparative examples show that the soil microbial high-efficiency water purification filter material prepared by the present invention is significantly better than traditional commercially available microbial filter materials in terms of pollutant removal efficiency and chemical stability, and has good application prospects.

[0231] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0232] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A preparation process for a high-efficiency soil microbial water purification filter media, characterized in that: The main raw materials are volcanic rock, activated carbon, bentonite, and modified cellulose, with the following mass proportions: volcanic rock 30-50 parts, activated carbon 20-30 parts, bentonite 10-20 parts, and modified cellulose 5-15 parts; the preparation process is as follows: S1) Crush volcanic rock into particles with a diameter of 0.1-0.5 mm, and calcine it in a high-temperature furnace at 800-1000℃ for 2-4 hours to further expand its pore structure and increase its specific surface area; S2) Activate the activated carbon using a physical activation method. At a high temperature of 900-1100℃, steam is introduced for 1-3 hours to increase the number of pores and active sites on the surface of the activated carbon. S3) The bentonite is purified to remove impurities and then mixed with an appropriate amount of water to make bentonite slurry. S4) Dissolve the modified cellulose in an appropriate amount of solvent to prepare a solution of a certain concentration; S5) Add the calcined volcanic rock particles and activated carbon particles to the bentonite slurry, stir evenly, then add the modified cellulose solution and continue stirring to ensure that all raw materials are fully mixed. S6) The mixture is granulated into particles with a diameter of 3-5 mm using a granulator; S7) Place the obtained granules in a drying oven and dry them to constant weight at 100-120℃. Then place them in a high-temperature furnace and sinter them at 500-700℃ for 2-3 hours to give them sufficient mechanical strength. S8) The sintered filter media particles are soaked in a bacterial solution containing a variety of soil microorganisms and cultured at 30-35℃ for 24-48 hours with shaking, so that the microorganisms can fully adhere to the surface and pores of the filter media, thus obtaining a high-efficiency soil microbial water purification filter media.

2. The preparation process of a high-efficiency soil microbial water purification filter material according to claim 1, characterized in that: In step S1): the volcanic rock is crushed into particles with a particle size of 0.1-0.5 mm and placed in a high-temperature furnace for calcination at 800-1000℃ for 2-4 hours. Calcination at 800-1000℃ increases the porosity of the volcanic rock from 20%-30% to 30%-40% and reduces the average pore size from micrometers to nanometers.

3. The preparation process of a high-efficiency soil microbial water purification filter material according to any one of claims 1-2, characterized in that: In step S2), the activated carbon is activated using a physical activation method. Steam is introduced at a high temperature of 900-1100℃ for 1-3 hours to increase the number of pores and active sites on the activated carbon surface. Specifically, the specific surface area increases from 200-400 m² / g for unactivated carbon to 800-1500 m² / g after activation. The number of pores changes from 0.1-0.3 cm³ / g to 0.5-1.2 cm³ / g; micropores smaller than 2 nm increase significantly, while mesopores of 2-50 nm increase moderately. Active sites primarily form oxygen-containing functional groups, such as carboxyl, hydroxyl, and carbonyl groups; more active sites are formed at irregularly arranged areas on the surface, reaching a site density of 10. 19 -10 20 Units / m² 4. The preparation process of a high-efficiency soil microbial water purification filter material according to claim 3, characterized in that: In step S3), the bentonite is purified to remove impurities, specifically as follows: S31) Crushing and grinding: The raw ore is crushed to 200 mesh, below 0.074mm; S32) Wet scrubbing: Water is added and stirred, with a solid content of 20-30%, and scrubbed for 10-30 minutes; S33) Hydrocyclone separation: A hydrocyclone with a diameter of 50-100mm is used to separate quartz and feldspar; S34) Sedimentation classification: The concentration and time are controlled to suspend montmorillonite and allow impurities to settle; S35) Dehydration and drying: Vacuum filtration or pressure filtration is used to dry to a moisture content of 8-12%.

5. The preparation process of a high-efficiency soil microbial water purification filter material according to claim 4, characterized in that... In step S3), the main impurities removed include: quartz (SiO2): reduced to below 5-10%; feldspar: reduced to below 3-5%; carbonate: reduced to below 1-2% by acid washing; iron oxide: reduced to below 0.5-1% by magnetic separation or acid washing; organic matter: reduced to below 0.3-0.5% by oxidation treatment. In step S3), it is then mixed with an appropriate amount of water to make bentonite slurry. The conventional formulation is as follows: solid content: 20-30% by mass, that is, 233-400mL of water per 100g of bentonite; high-quality high-viscosity slurry: solid content 15-20%, that is, 400-567mL of water per 100g of bentonite.

6. The preparation process of a high-efficiency soil microbial water purification filter material according to claim 5, characterized in that... In step S4), the modified cellulose includes CMC, HPMC, CA, cellulose-g-polyacrylamide, and oxidized cellulose.

7. The preparation process of a high-efficiency soil microbial water purification filter material according to claim 6, characterized in that... Step S4) Use carboxymethyl cellulose (CMC), solvent: distilled water, concentration range: 1-5%, slowly disperse and stir in water to avoid clumping, and a viscous solution can be formed.

8. The preparation process of a high-efficiency soil microbial water purification filter material according to claim 7, characterized in that... Step S4) The carboxymethyl chemical modification process is as follows: Modified cellulose is usually modified through chemical modification methods such as carboxymethylation, and the specific steps include: Alkali treatment: Natural cellulose is soaked in an alkaline solution to make the hydroxyl groups on its cellulose molecular chains more active; Etherification reaction: Add carboxymethylating agents, such as chloroacetic acid and sodium hydroxide, and carry out the etherification reaction under alkaline conditions to introduce carboxymethyl groups (-O-COCH3) onto the cellulose molecular chain. Neutralization and washing: After the reaction is complete, the mixture is neutralized and washed to remove unreacted reagents and impurities, yielding the modified carboxymethyl cellulose; Drying and pulverizing: The neutralized product is dried to remove moisture, and then pulverized into the required particle size.

9. The preparation process of a high-efficiency soil microbial water purification filter material according to claim 8, characterized in that... In step S7), the obtained granules are placed in a drying oven and dried to constant weight at 100-120℃, and then sintered in a high-temperature furnace at 500-700℃ for 2-3 hours to give them sufficient mechanical strength; specifically as follows: S71) Drying and sintering are as follows: During the drying process, free water and some bound water in the particles are removed, the internal moisture of the particles evaporates, forming a preliminary porous structure, and the binders such as modified cellulose begin to soften and cross-link, initially binding the various components together. The sintering process for S72 is as follows: Modified cellulose is completely carbonized or burned away, leaving a porous framework; clay minerals such as bentonite undergo dehydration, phase transformation and partial melting, and neck connections are formed between adjacent particles; the structure becomes dense, the pore structure is rearranged, some small pores disappear and large pores are retained; After sintering, the compressive strength reaches 5-20 MPa, and the specific surface area reaches 100-300 m² / g. After sintering, a multi-level porous structure is formed, with micropores, mesopores, and macropores coexisting. The total pore volume reaches 0.3-0.8 cm³ / g, and the pore size distribution is mainly concentrated in 2-50 nm, which is suitable for microbial attachment and material transport. In S8), soil microorganisms include Bacillus, Pseudomonas, and nitrifying bacteria, with the bacterial concentration controlled at 10. 8 Up to 10 10 The CFU / mL level was between 10 CFU / mL and the microbial attachment level was between 10 CFU / mL and 10 CFU / mL. 7 Up to 10 9 The amount of adhesion between CFUs is beneficial for the rapid formation of biofilm.

10. A high-efficiency soil microbial water purification filter material, prepared according to the preparation process of any one of claims 1-9.

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