A mineral-microorganism porous filter material, a preparation method and application thereof

Abstract

The present application relates to the technical field of pollution purification material preparation, and particularly relates to a mineral-microorganism porous filter material, a preparation method and application thereof.The preparation method comprises the following steps: A) mixing fly ash, water and degradable water-soluble polymer to obtain a slurry; B) drying the slurry after the slurry is made into particles; and C) mixing the dried particles with a compound aerobic microbial culture solution, and aging to obtain a mineral-microorganism porous filter material.The present application adopts a technical route of microbial degradation, and the prepared porous material has a large specific surface area, which is beneficial to improving the contact area of the filter material and sludge, the degradable polymer serves as a nutrient substrate, which is beneficial to the growth of microorganisms, the prepared material has physical adsorption filtration and microbial degradation functions, and can effectively remove organic pollutants, nitrogen and phosphorus-containing pollutants, heavy metals and other pollutants in sludge.

Description

Technical Field

[0001] This invention relates to the field of pollution purification material preparation technology, and in particular to a mineral-microbial porous filter material, its preparation method and application. Background Technology

[0002] Sludge treatment technology is an important environmental protection technology, widely used in municipal sludge treatment, wastewater treatment, and wetland eutrophication control. The key to sludge treatment lies in adsorbing or degrading excess organic matter in the sludge, reducing the chemical oxygen demand (COD) of the sludge, and removing excess phosphorus and nitrogen-containing substances, heavy metal ions, and other harmful substances from the sludge. There are three main traditional sludge treatment methods: The first is to directly remove organic pollutants and solidify heavy metals through high-temperature calcination (e.g., patents CN202010849381.6 and CN202023020081.1); the second is to add strong oxidants, which on the one hand oxidize and degrade organic pollutants, and on the other hand oxidize heavy metal ions to a high valence state that is easy to precipitate in order to remove heavy metals (e.g., patents CN201711410512.5 and CN201810680059.8); the third is to use activated carbon as an adsorbent to adsorb pollutants (e.g., patents CN201721447464.2, CN202022858940.8 and CN202222174662.3). In order to solve the problems of low pollution removal efficiency, high cost and energy consumption, and complex equipment and processes of traditional technologies, new technologies such as photocatalytic degradation of sludge (e.g., patents CN201910640509.5, CN202123090293.1) and microbial degradation (e.g., patents CN202080089768.4, CN202121336041.X, CN202110984798.8) have been gradually developed and applied in recent years.

[0003] Among the technologies mentioned above, high-temperature calcination obviously suffers from drawbacks such as high energy consumption, reliance on complex high-temperature calcination equipment, complex processes, and high risks, and is gradually being phased out. Strong oxidants are expensive and can easily introduce new pollution after sludge treatment. Activated carbon, while environmentally friendly, is costly, and its physical adsorption results in a low saturation adsorption capacity. Furthermore, the adsorbed activated carbon is difficult to remove from the sludge, limiting its potential application in sludge treatment. Photocatalytic degradation has low efficiency and relies on catalysts containing heavy metals (mainly copper, cadmium, and indium), potentially introducing new pollution. Microbial degradation avoids the problems of the above four technologies, offering low cost and energy consumption, simple processes, and environmental friendliness.

[0004] In engineering applications, microorganisms need to attach to a carrier. For example, the Xi'an East Main Canal Ecological Restoration Project used a combination of biological filter dams, biological rope packing materials, and micro-nano aeration systems to treat riverbed pollution. The removal rates of COD, ammonia nitrogen, and organic phosphorus were 8.30%, 61.24%, and 57.77%, respectively, which is still not ideal (Ma Ying. Journal of Environmental Engineering, 2022, 16(05): 1721-1729). This is because traditional microbial carriers have a small specific surface area (usually <0.1m²). 2 The low contact between the sludge and the sludge ( / g) results in low sludge treatment efficiency. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a mineral-microorganism porous filter material, its preparation method and application. The mineral-microorganism porous filter material prepared by the present invention has a high sludge treatment efficiency.

[0006] This invention provides a method for preparing a mineral-microbial porous filter material, comprising the following steps:

[0007] A) Mix fly ash, water, and biodegradable water-soluble polymer to obtain a slurry;

[0008] B) After the slurry is granulated, it is dried;

[0009] C) The dried particles are mixed with a composite aerobic microbial culture medium and aged to obtain a mineral-microbial porous filter material.

[0010] Preferably, in step A), the fly ash is harmless fly ash; the heavy metal content in the fly ash is below 25 ppm;

[0011] The particle size of the fly ash is less than 10 μm;

[0012] The biodegradable water-soluble polymer includes at least one of polyvinyl alcohol, polylactic acid, and carboxymethyl cellulose.

[0013] Preferably, in step A), the degradable water-soluble polymer comprises polyvinyl alcohol and carboxymethyl cellulose in a mass ratio of 1:1.

[0014] Preferably, in step A), the mass of the water is 30% to 40% of the mass of the fly ash, and the mass of the biodegradable water-soluble polymer is 5% to 15% of the mass of the fly ash.

[0015] Preferably, in step B), the size of the particles is 1 to 5 cm;

[0016] The moisture content of the dried granules is no more than 10%.

[0017] Preferably, in step C), the composite aerobic microorganisms include yeast, filamentous fungi, actinomycetes, and microalgae; and the mass of each microorganism accounts for no less than 1% of the total mass of all microorganisms.

[0018] The mass ratio of the dried granules to the composite aerobic microbial culture medium is 5-10:1;

[0019] The aging temperature is 10–40°C, and the time is more than 120 hours.

[0020] Preferably, in step C), the porosity of the mineral-microbial porous filter material is 40%–60%, the pore size is <1 μm, and the specific surface area is >10 m². 2 / g.

[0021] The present invention also provides a mineral-microbial porous filter material prepared by the preparation method described above.

[0022] This invention also provides an application of the mineral-microbial porous filter material described above as a sludge treatment material.

[0023] The present invention also provides a sludge treatment method, comprising the following steps:

[0024] Mix the sludge to be treated with the mineral-microbial porous filter material and degrade it at 24–30°C.

[0025] The mineral-microorganism porous filter material is the same as the mineral-microorganism porous filter material described above.

[0026] This invention provides a method for preparing a mineral-microbial porous filter material, comprising the following steps: A) mixing fly ash, water, and a biodegradable water-soluble polymer to obtain a slurry; B) granulating the slurry and drying it; C) mixing the dried granules with a composite aerobic microbial culture medium and aging it to obtain the mineral-microbial porous filter material. This invention employs a microbial degradation technology route. To increase the specific surface area of ​​the microbial system, a method for preparing a mineral-microbial porous filter material using a biodegradable polymer binder has been developed. The porous material prepared by this method is beneficial for increasing the contact area between the filter material and sludge. The biodegradable polymer binder serves as a nutrient matrix, promoting microbial growth. The material combines physical adsorption filtration and microbial degradation functions, effectively removing organic pollutants, nitrogen- and phosphorus-containing pollutants, heavy metals, and other pollutants from sludge. Furthermore, since the raw materials used in this material are all low-cost and low-pollution raw materials, it reduces costs while avoiding secondary pollution, giving it the potential for large-scale application. Attached Figure Description

[0027] Figure 1A process flow diagram for preparing a mineral-microbial porous filter material is provided as an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of the mineral-microorganism porous filter material prepared in Example 1 of the present invention;

[0029] Figure 3 This is an appearance diagram of the mineral-microorganism porous filter material prepared in Example 1 of the present invention;

[0030] Figure 4 This is a SEM image of the mineral-microbial porous filter material prepared in Example 1 of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a method for preparing a mineral-microbial porous filter material, comprising the following steps:

[0033] A) Mix fly ash, water, and biodegradable water-soluble polymer to obtain a slurry;

[0034] B) After the slurry is granulated, it is dried;

[0035] C) The dried particles are mixed with a composite aerobic microbial culture medium and aged to obtain a mineral-microbial porous filter material.

[0036] Figure 1 A flowchart illustrating the preparation process of a mineral-microbial porous filter material according to an embodiment of the present invention.

[0037] In step A):

[0038] Fly ash, water, and biodegradable water-soluble polymer are mixed to obtain a slurry.

[0039] In some embodiments of the present invention, the fly ash is harmless fly ash, and the heavy metal content in the fly ash is below 25 ppm. The heavy metals are copper, lead, cadmium, and other heavy metal pollutants specified in the national soil environmental quality standard GB15618-1995.

[0040] The particle size of the fly ash is less than 10 μm.

[0041] In this invention, the biodegradable water-soluble polymer is a binder. The biodegradable water-soluble polymer includes at least one of biocompatible, water-soluble, and biodegradable polymers, specifically at least one of polyvinyl alcohol, polylactic acid, and carboxymethyl cellulose. In some embodiments of this invention, the biodegradable water-soluble polymer includes polyvinyl alcohol and carboxymethyl cellulose in a mass ratio of 1:1. The polyvinyl alcohol is polyvinyl alcohol 2000.

[0042] In some embodiments of the present invention, the mixing method includes, but is not limited to, stirring, ball milling, or sand milling.

[0043] In some embodiments of the present invention, the mass of the water is 30% to 40% of the mass of the fly ash, specifically 30%, 35%, or 40%; the mass of the biodegradable water-soluble polymer is 5% to 15% of the mass of the fly ash, specifically 7.5%, 10%, or 15%.

[0044] In step B):

[0045] The slurry is granulated and then dried.

[0046] In some embodiments of the present invention, the slurry is granulated by means of roller forming, die forming, or any other granulation method.

[0047] The present invention does not impose any particular limitation on the shape of the particles, which can be spherical, cubic, cylindrical, hollow columnar, or other arbitrary geometric shapes.

[0048] In some embodiments of the present invention, the size of the particles is 1 to 5 cm.

[0049] In some embodiments of the present invention, the drying method includes heating drying, vacuum drying, flash drying, or other arbitrary drying methods. In some embodiments, heating drying is used, and the heating drying temperature is 60–90°C; specifically, 60°C.

[0050] The moisture content of the dried granules is no more than 10%; specifically 10%, 8%, and 6%.

[0051] In step C):

[0052] The dried particles are mixed with a composite aerobic microbial culture medium and aged to obtain a mineral-microbial porous filter material.

[0053] Specifically, the dried particles are impregnated in a composite aerobic microbial culture medium and aged to obtain a mineral-microbial porous filter material.

[0054] In some embodiments of the present invention, the composite aerobic microorganisms include yeast, filamentous fungi, actinomycetes and microalgae; in the composite aerobic microorganisms, the mass of each microorganism accounts for not less than 1% of the total mass of all microorganisms; specifically, 1% to 5%.

[0055] In some embodiments of the present invention, the composite aerobic microbial culture medium can be a commercially available microbial agent containing yeast, filamentous fungi, actinomycetes, and microalgae, or a self-made microbial agent. The self-made microbial agent can be prepared by culturing yeast, filamentous fungi, actinomycetes, cyanobacteria, and spirulina in a sucrose-peptone culture medium, or by culturing natural activated sludge leachate in a sucrose-peptone culture medium (culturing temperature 25–29°C, specifically 27°C; time 7–15 days, specifically 10 days). The pH value of the sucrose-peptone culture medium is 6.0–8.0; before culturing, the number of microorganisms per unit volume in the sucrose-peptone culture medium is 10. 3 ~10 9 The activated sludge leachate from natural sources can be riverbed silt leachate.

[0056] In some embodiments of the present invention, the mass ratio of the dried particles to the composite aerobic microbial culture medium is 5 to 10:1; specifically 5:1, 8:1, and 10:1.

[0057] In some embodiments of the present invention, the aging temperature is 10-40°C, specifically 25°C or 28°C; the aging environment is air or other oxygen-containing environment (oxygen partial pressure ≥15%), and the aging time is more than 120 hours, specifically 240 hours or 216 hours.

[0058] The present invention also provides a mineral-microbial porous filter material prepared by the preparation method described above.

[0059] The mineral-microorganism porous filter material provided by the present invention uses fly ash particles as a matrix, and the surface of the fly ash particles is coated with a biodegradable water-soluble polymer as a binder to form porous particles; microorganisms grow on the surface and in the pores of the porous particles to form a mineral-microorganism porous composite structure.

[0060] In some embodiments of the present invention, the mineral-microbial porous filter material has a porous structure with a porosity of 40% to 60%, a pore size of <1 μm, and a specific surface area of ​​>10 m². 2 / g.

[0061] This invention also provides an application of the mineral-microbial porous filter material described above as a sludge treatment material.

[0062] Specifically, the present invention provides a sludge treatment method, comprising the following steps:

[0063] Mix the sludge to be treated with the mineral-microbial porous filter material and degrade it at 24–30°C.

[0064] The mineral-microorganism porous filter material is the same as the mineral-microorganism porous filter material described above.

[0065] In some embodiments of the present invention, the sludge to be treated has an ammonia nitrogen content of 1-5 ppm, a total phosphorus content of 0.5-2 ppm, a heavy metal content of 1-5 ppm, and a COD content of 50-150 ppm.

[0066] In some embodiments of the present invention, the mass ratio of the sludge to be treated to the mineral-microbial porous filter material is 10 to 100:1; specifically 100:1.

[0067] The mixing can be achieved by stirring.

[0068] The degradation was carried out under normal pressure. The degradation temperature was 27°C; the time was 230–250 h, specifically 240 h.

[0069] The preparation method of the mineral-microbial porous filter material provided by this invention uses harmless fly ash, biodegradable water-soluble polymers, and microbial preparations, all of which are low-cost raw materials. It eliminates the need for strong oxidants, activated carbon, precious metals, and other materials, thus reducing raw material costs.

[0070] The preparation method does not require a high-temperature calcination step.

[0071] The preparation method provided by this invention includes steps such as mixing, granulation, drying, impregnation, and aging, without relying on complex equipment and processes.

[0072] The mineral-microbial porous filter material prepared by this invention has a large specific surface area and contains composite aerobic microorganisms, which can not only achieve efficient adsorption of pollutants, but also remove various pollutants in sludge through biodegradation and solidification, resulting in high sludge treatment efficiency.

[0073] The raw materials used in this invention do not contain toxic or harmful substances, and do not generate secondary pollution during use.

[0074] The method for preparing mineral-microbial porous filter materials provided by this invention can achieve ton-scale production, which is conducive to industrialization and promotion.

[0075] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.

[0076] To further illustrate the present invention, the following detailed description of a mineral-microbial porous filter material and its preparation method provided by the present invention is provided in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0077] In the following embodiments:

[0078] The fly ash is harmless fly ash, which comes from the Inner Mongolia Power Generation Company of China Huadian Corporation. The heavy metal content is below 25 ppm. The heavy metals mentioned are copper, lead, cadmium and other heavy metal pollutants specified in the national soil environmental quality standard GB15618-1995. The particle size of the harmless fly ash is below 10 μm.

[0079] Preparation of composite aerobic microbial culture medium:

[0080] It was prepared by culturing riverbed silt leachate in sucrose-peptone medium at 27°C for 10 days.

[0081] The sucrose-peptone culture medium has a pH of 6.0–8.0 and is commercially available. Before culturing, the number of microorganisms per unit volume in the sucrose-peptone culture medium is approximately 10. 6 cells / mL;

[0082] In the composite aerobic microbial culture medium, the mass of each microorganism accounts for 1% to 5% of the total mass of all microorganisms.

[0083] Example 1

[0084] A method for preparing a mineral-microbial porous filter material includes the following steps:

[0085] 1) Mix fly ash, water, and biodegradable water-soluble polymer to obtain a slurry;

[0086] The biodegradable water-soluble polymer is polyvinyl alcohol 2000 and carboxymethyl cellulose in a mass ratio of 1:1; the mass of the biodegradable water-soluble polymer is 7.5% of the mass of fly ash.

[0087] The mass of the water is 30% of the mass of the fly ash;

[0088] 2) The slurry is processed by a roller method to obtain spherical particles with a size of 1-5 cm;

[0089] 3) The spherical particles are dried at 60°C; the moisture content of the dried particles is 10%.

[0090] 4) The dried granules are mixed with a composite aerobic microbial culture medium and aged at 25°C for 240 hours under air conditions to obtain a mineral-microbial porous filter material.

[0091] The mass ratio of the dried granules to the composite aerobic microbial culture medium is 5:1.

[0092] Figure 2 This is a schematic diagram of the structure of the mineral-microorganism porous filter material prepared in Example 1 of the present invention. From... Figure 2 It is known that the mineral-microorganism porous filter material uses fly ash particles as a matrix, and the surface of the fly ash particles is coated with a biodegradable water-soluble polymer as a binder to form porous particles; microorganisms grow on the surface and in the pores of the porous particles to form a microorganism-mineral porous composite structure.

[0093] Figure 3 This is an appearance diagram of the mineral-microbial porous filter material prepared in Example 1 of the present invention.

[0094] Figure 4 This is a SEM image of the mineral-microbial porous filter material prepared in Example 1 of the present invention (the width of the material area captured in the image is 100 μm). The white part in the image represents pores (porosity between 40% and 60%), with a pore size <1 μm and a specific surface area >10 m². 2 / g.

[0095] Example 2

[0096] A method for preparing a mineral-microbial porous filter material includes the following steps:

[0097] 1) Mix fly ash, water, and biodegradable water-soluble polymer to obtain a slurry;

[0098] The biodegradable water-soluble polymer is polyvinyl alcohol 2000 and carboxymethyl cellulose in a mass ratio of 1:1; the mass of the biodegradable water-soluble polymer is 10% of the mass of fly ash.

[0099] The mass of the water is 35% of the mass of the fly ash;

[0100] 2) The slurry is processed by a roller method to obtain spherical particles with a size of 1-5 cm;

[0101] 3) The spherical particles are dried at 75°C; the moisture content of the dried particles is 8%.

[0102] 4) The dried granules are mixed with a composite aerobic microbial culture medium and aged at 25°C for 240 hours under air conditions to obtain a mineral-microbial porous filter material.

[0103] The mass ratio of the dried granules to the composite aerobic microbial culture medium is 8:1.

[0104] Testing revealed that the porosity of the mineral-microbial porous filter material was between 40% and 60%, with a pore size <1μm and a specific surface area >10m². 2 / g.

[0105] Example 3

[0106] A method for preparing a mineral-microbial porous filter material includes the following steps:

[0107] 1) Mix fly ash, water, and biodegradable water-soluble polymer to obtain a slurry;

[0108] The biodegradable water-soluble polymer is polyvinyl alcohol 2000 and carboxymethyl cellulose in a mass ratio of 1:1; the mass of the biodegradable water-soluble polymer is 15% of the mass of fly ash.

[0109] The mass of the water is 40% of the mass of the fly ash;

[0110] 2) The slurry is processed by a roller method to obtain spherical particles with a size of 1-5 cm;

[0111] 3) The spherical particles are dried at 90°C; the moisture content of the dried particles is 6%.

[0112] 4) The dried granules are mixed with a composite aerobic microbial culture medium and aged at 28°C for 216 hours under air conditions to obtain a mineral-microbial porous filter material.

[0113] The mass ratio of the dried granules to the composite aerobic microbial culture medium is 10:1.

[0114] Testing revealed that the porosity of the mineral-microbial porous filter material was between 40% and 60%, with a pore size <1μm and a specific surface area >10m². 2 / g.

[0115] Example 4

[0116] The difference from Example 1 is as follows:

[0117] The biodegradable water-soluble polymer in Example 1 was replaced with polylactic acid and carboxymethyl cellulose in a mass ratio of 1:1.

[0118] Testing revealed that the porosity of the mineral-microbial porous filter material was between 40% and 60%, with a pore size <1μm and a specific surface area >10m². 2 / g.

[0119] Example 5

[0120] The difference from Example 1 is as follows:

[0121] The biodegradable water-soluble polymer in Example 1 was replaced with polyvinyl alcohol 2000.

[0122] Testing revealed that the porosity of the mineral-microbial porous filter material was between 40% and 60%, with a pore size <1μm and a specific surface area >10m². 2 / g.

[0123] Comparative Example 1

[0124] The difference from Example 1 is as follows:

[0125] Step 1) does not contain biodegradable water-soluble polymers.

[0126] Comparative Example 2

[0127] The difference from Example 1 is as follows:

[0128] The biodegradable water-soluble polymer in Example 1 was replaced with ethyl cellulose (ethyl cellulose is insoluble in water).

[0129] Application examples

[0130] A sludge treatment method includes the following steps:

[0131] The mineral-microbial porous filter materials of Examples 1-5 and Comparative Examples 1-2 were mixed with the sludge to be treated (the sludge used was sludge from the Pingshuo Coal Mine in Shuozhou City, Shanxi Province) at a mass ratio of 1:100 and decomposed at 27°C and normal pressure for 240 hours.

[0132] Meanwhile, this invention also uses existing biological rope + bacterial agent treatment as a control group, specifically including:

[0133] The existing biological rope + bacterial agent was mixed with the sludge to be treated (the sludge used was sludge from the Pingshuo Coal Mine in Shuozhou City, Shanxi Province) at a mass ratio of 1:100, and decomposed at 27℃ and normal pressure for 240 hours.

[0134] The treatment effect was evaluated based on the pollutant content of the sludge leachate. The initial ammonia nitrogen content, total phosphorus content, and heavy metal content in the sludge leachate are shown in Table 1.

[0135] The pollutant testing standards are based on GB / T 5750.

[0136] The processing results are shown in Table 1.

[0137] Table 1. Treatment effects of mineral-microbial porous filter materials in Examples 1-5 and Comparative Examples 1-2

[0138]

[0139] As shown in Table 1, compared to existing bio-rope + microbial agent combinations, the mineral-microbial porous filter material provided by this invention achieves significantly better ammonia nitrogen removal efficiency, total phosphorus removal efficiency, heavy metal removal efficiency, and COD removal efficiency, with a significantly higher sludge treatment efficiency. In the preparation of the mineral-microbial porous filter material, removing the biodegradable water-soluble polymer significantly reduces the sludge treatment efficiency.

[0140] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a mineral-microbial porous filter material, comprising the following steps: A) Fly ash, water, and a biodegradable water-soluble polymer are mixed to obtain a slurry; the fly ash is harmless fly ash; the heavy metal content in the fly ash is below 25 ppm; the particle size of the fly ash is below 10 μm; the biodegradable water-soluble polymer is at least one of polyvinyl alcohol, polylactic acid, and carboxymethyl cellulose. The water content is 30% to 40% of the fly ash content, and the biodegradable water-soluble polymer content is 5% to 15% of the fly ash content. B) After the slurry is granulated, it is dried; the size of the granules is 1-5 cm; the moisture content of the dried granules is not greater than 10%; C) The dried granules are mixed with a composite aerobic microbial culture medium and aged to obtain a mineral-microbial porous filter material; The composite aerobic microorganisms include yeasts, filamentous fungi, actinomycetes, and microalgae; in the composite aerobic microorganisms, the mass of each microorganism accounts for no less than 1% of the total mass of all microorganisms. The mass ratio of the dried granules to the composite aerobic microbial culture medium is 5~10:1; The aging temperature is 10~40℃ and the time is more than 120 hours; The mineral-microbial porous filter material has a porosity of 40%~60%, a pore size of <1 μm, and a specific surface area of ​​>10 m². 2 / g.

2. The preparation method according to claim 1, characterized in that, In step A), the degradable water-soluble polymer includes polyvinyl alcohol and carboxymethyl cellulose in a mass ratio of 1:

1.

3. A mineral-microbial porous filter material prepared by the preparation method according to any one of claims 1 to 2.

4. The application of the mineral-microbial porous filter material as described in claim 3 as a sludge treatment material.

5. A sludge treatment method, comprising the following steps: Mix the sludge to be treated with the mineral-microbial porous filter material and degrade it at 24~30℃. The mineral-microorganism porous filter material is the mineral-microorganism porous filter material as described in claim 4.

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