Coal-based solid waste sewage treatment material, preparation method thereof and sewage treatment method

Abstract

The invention provides a coal-based solid waste sewage treatment material, a preparation method thereof and a sewage treatment method, and belongs to the technical field of sewage treatment. The coal-based solid waste sewage treatment material is prepared from the following raw materials in parts by weight: 70-85 parts of fly ash, 5-15 parts of gasified slag, 1-5 parts of sodium thiosulfate and 5-9 parts of humic acid, wherein the pH value of the leachate of the fly ash is greater than 11.0, and the content of calcium ions is greater than or equal to 200mg / L. The coal-based solid waste sewage treatment material is prepared by taking coal-based solid waste fly ash and gasified slag as raw materials and mixing the raw materials with sodium thiosulfate and humic acid, so that on one hand, the problem of comprehensive utilization of fly ash and gasified slag is solved, and on the other hand, heavy metals in sewage are solidified through a synergistic effect among the raw materials in the material, so that the heavy metals in the sewage are effectively prevented from being polluted. Heavy metals are fixed in the coal-based solid waste porous material, so that the pollution problem of heavy metal sewage is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to a coal-based solid waste sewage treatment material, a preparation method thereof, and a sewage treatment method. Background Art

[0002] Fly ash is a volcanic ash-like mixed material formed after high-temperature combustion of coal powder. Its main components are silicon dioxide, aluminum oxide, iron oxide, calcium oxide and unburned carbon. At present, fly ash is mainly used as building materials, agricultural fertilizers, soil conditioners, recycled industrial raw materials and environmental materials. For example, Chinese patent application document CN109569499A discloses a preparation method and application of thiol-functionalized fly ash, which uses hydroxylated fly ash after treatment as a carrier, grafts thiol groups on the surface, and can form stable thiol complexes with heavy metal ions. Through the above method, the prepared thiol-functionalized fly ash can adsorb heavy metal ions in water well and is used to treat heavy metal pollution in water areas. The technical solution has low energy consumption, low cost, simple process, easy raw materials, and good environmental affinity in the preparation process and product. The prepared fly ash has a high specific surface area, good adsorption and stability for heavy metal ions in aqueous solution, mild application conditions, and a wide range of applicable metals, and is expected to become a new type of water treatment adsorbent.

[0003] The main component of coal gasification ash is SiO 2 、Al 2 O 3 , CaO and residual carbon, etc., and its chemical properties are relatively stable, so it is widely used. For example, Chinese patent application document CN109734144A discloses a sewage treatment material based on coal gasification slag and its preparation method, the material includes the following raw materials: coal gasification slag, ultrafine cement, bentonite, chopped glass fiber and water reducer; the weight parts of the raw materials are: 75-85 parts of coal gasification slag, 15-25 parts of ultrafine cement, 1-5 parts of bentonite, 0.1-0.2 parts of chopped glass fiber, 0.1-0.25 parts of water reducer; the coal gasification slag is a flocculent, loose and porous three-dimensional structure; the density of the coal gasification slag is 1.782g / cm 3 , with a specific surface area of ​​240 to 260 m 2 / kg; the ultrafine cement is silicate cement with a strength grade of not less than 52.5 and a specific surface area of ​​not less than 330m 2 / kg; the particle size of the bentonite is less than 0.075mm, the content of montmorillonite in the bentonite is 95-98wt%, and the montmorillonite in the bentonite is a three-layer lamellar structure, with aluminum oxide octahedron in the middle and silicon oxide tetrahedron above and below; the water reducer is a polycarboxylic acid-based high-efficiency water reducer.

[0004] Although the above technologies disclose the application of fly ash and coal gasification ash residue in sewage treatment, there is no report on the use of a combination of fly ash, gasification slag, sodium thiosulfate and humic acid to prepare a heavy metal sewage treatment material. Summary of the invention

[0005] In view of this, the present invention provides a coal-based solid waste sewage treatment material, a preparation method thereof and a sewage treatment method. The coal-based solid waste sewage treatment material provided in the present invention can not only solve the problem of comprehensive utilization of fly ash and gasified slag, but also solidify heavy metals in sewage and fix the heavy metals in the coal-based solid waste porous material, which is conducive to solving the pollution problem of heavy metal sewage.

[0006] An object of the present invention is to provide a method for preparing coal-based solid waste sewage treatment materials.

[0007] The coal-based solid waste sewage treatment material is prepared by using raw materials including the following components in parts by weight: 70-85 parts of fly ash, 5-15 parts of gasified slag, 1-5 parts of sodium thiosulfate, and 5-9 parts of humic acid;

[0008] Wherein, the pH value of the fly ash leaching solution is greater than 11.0, and the calcium ion content is greater than or equal to 200 mg / L.

[0009] In the present invention, the fly ash leaching solution is prepared by the method specified in HJ 557-2010 "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method".

[0010] The inventors have found that the coal-based solid waste sewage treatment material prepared by mixing fly ash, gasification slag, sodium thiosulfate and humic acid in a certain proportion can solidify heavy metals in sewage. On the one hand, the high alkalinity fly ash and humic acid synergistically adsorb and synergistically precipitate heavy metals in sewage, significantly reducing the heavy metal content in sewage. On the other hand, fly ash with high calcium ion content exhibits synergistic gelling properties with gasification slag and sodium thiosulfate, and the synergistically adsorbed and synergistically precipitated heavy metals are further gelled and solidified through gelling reaction.

[0011] In some embodiments, the moisture content of the gasified slag is 15-45%; in some preferred embodiments, the gasified slag is gasified fine slag; in some more preferred embodiments, the median particle size of the gasified fine slag is 20-50 μm, and the specific surface area is 80-250 m 2 / g, and the average pore size of the mesopores is 2-10nm.

[0012] In the present invention, the gasified slag with a high water content is directly used for gelling and solidification reaction, avoiding the dehydration step before the use of the gasified slag, which not only saves costs but also improves the direct resource utilization rate of the gasified slag. In addition, since the gasified slag has a high specific surface area and mesoporous properties, the prepared coal-based solid waste sewage treatment material also has a high specific surface area and mesoporous properties.

[0013] In some embodiments, the humic acid is one or more of mineral-derived humic acid, biomass-derived humic acid, and fulvic acid.

[0014] In some embodiments, the specific surface area of ​​the coal-based solid waste sewage treatment material is 20-150 m 2 / g, and it has a mesoporous structure with an average mesopore diameter of 5-50nm.

[0015] In the present invention, since the coal-based solid waste sewage treatment material has a high specific surface area and mesoporous properties, it can enhance the effect of synergistic adsorption and synergistic precipitation of heavy metals in sewage, and further improve the removal effect of heavy metals in sewage.

[0016] In some embodiments, the preparation method comprises the following steps:

[0017] 1) mixing fly ash and humic acid to obtain a first mixture;

[0018] 2) mixing the first mixture and sodium thiosulfate to obtain a second mixture;

[0019] 3) Continue to mix the second mixture with the gasified slag to obtain a coal-based solid waste sewage treatment material.

[0020] The inventors further discovered that the mixing order of the raw materials has an important influence on the solidification performance of the coal-based solid waste sewage treatment material. If the mixing order of the sodium thiosulfate in step 2) and the gasified slag in step 3) is reversed, the solidification effect of the obtained coal-based solid waste sewage treatment material on the heavy metals in the sewage will be adversely affected.

[0021] Another object of the present invention is to provide a coal-based solid waste sewage treatment material prepared by any of the preparation methods described above.

[0022] Another object of the present invention is to provide the use of the above-mentioned coal-based solid waste sewage treatment material in sewage treatment.

[0023] Another object of the present invention is to provide a method for treating sewage using the coal-based solid waste sewage treatment material described above.

[0024] The method comprises the following steps:

[0025] The coal-based solid waste sewage treatment material and sewage are mixed and allowed to stand to form a coal-based solid waste porous material; based on the mass of the coal-based solid waste sewage treatment material, the amount of sewage used is 25-45%.

[0026] In some embodiments, the sewage is heavy metal sewage; in some embodiments, the heavy metal is one or more of Cd, Cu, Mn, Ni, Pb, and Zn.

[0027] Preferably, the heavy metal content ranges are as follows: 0.1 mg / L<Cd≤5 mg / L, 0.5 mg / L<Cu≤50 mg / L, 2 mg / L<Mn≤25 mg / L, 1 mg / L<Ni≤50 mg / L, 1 mg / L<Pb≤20 mg / L, 2 mg / L<Zn≤100 mg / L.

[0028] In the present invention, the content of heavy metal elements is measured by the method required by GB 8978-1996 "Integrated Wastewater Discharge Standard".

[0029] In some embodiments, the standing time is 1-7 days.

[0030] In the present invention, after standing, a coal-based solid waste porous material is obtained; wherein, the leachate of the coal-based solid waste porous material is prepared by the method specified in HJ 557-2010 "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method", and the content of heavy metal elements in the leachate of the coal-based solid waste porous material is measured according to the method used above, and the specific contents are as follows: Cd≤0.1mg / L, Cu≤0.5mg / L, Mn≤2.0mg / L, Ni≤1.0mg / L, Pb≤1.0mg / L, Zn≤2.0mg / L.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] In the present invention, solid waste fly ash and gasification slag are used as raw materials, and after mixing with sodium thiosulfate and humic acid, a coal-based solid waste sewage treatment material is prepared. On the one hand, the problem of comprehensive utilization of fly ash and gasification slag is solved. At the same time, the raw materials in the above materials solidify the heavy metals in the sewage through synergy, and fix the heavy metals in the coal-based solid waste porous material, which is conducive to solving the pollution problem of heavy metal sewage. In addition, the heavy metal content of the leachate of the coal-based solid waste porous material obtained after fixation is extremely low, and it can be further used as a harmless material, for example, it can be further utilized as a backfill material. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The experimental methods without specific conditions in the examples are usually carried out according to conventional conditions and conditions described in the manual, or according to conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0035] In the following examples, the fly ash leaching solution was prepared by the method specified in HJ 557-2010 "Toxicity leaching method for solid waste leaching - horizontal oscillation method".

[0036] Example 1

[0037] Coal-based solid waste sewage treatment materials, the raw materials of which include the following components, by weight: 70 parts of fly ash, 15 parts of gasified slag, 5 parts of sodium thiosulfate, and 9 parts of mineral source humic acid;

[0038] The pH value of the fly ash leaching solution is 12.1, and the calcium ion content is 720 mg / L; the water content of the gasified slag is 15%, the median particle size is 26 μm, and the specific surface area is 213 m 2 / g, and the average mesopore diameter is 6.5nm.

[0039] The steps of preparing the coal-based solid waste sewage treatment material and using the coal-based solid waste sewage treatment material for sewage treatment include:

[0040] 1) mixing 70 parts of fly ash and 9 parts of mineral source humic acid to obtain a first mixture;

[0041] 2) mixing the first mixture with 5 parts of sodium thiosulfate to obtain a second mixture;

[0042] 3) Continue to mix the second mixture with 15 parts of gasified slag to obtain a coal-based solid waste sewage treatment material; the specific surface area of ​​the coal-based solid waste sewage treatment material is 76m 2 / g, and the average mesopore diameter is 7.2nm.

[0043] 4) The coal-based solid waste sewage treatment material obtained in step 3) is mixed with heavy metal sewage (the heavy metal content is shown in Table 2 below), wherein the amount of sewage is 45% based on the mass of the coal-based solid waste water treatment material; after standing for 5 days, a coal-based solid waste porous material is obtained.

[0044] Example 2

[0045] Coal-based solid waste sewage treatment materials, the raw materials of which include the following components, by weight: 85 parts of fly ash, 5 parts of gasified slag, 1 part of sodium thiosulfate, and 5 parts of biomass humic acid;

[0046] The pH value of the fly ash leaching solution is 11.7, and the calcium ion content is 293 mg / L; the water content of the gasified slag is 45%, the median particle size is 20 μm, and the specific surface area is 250 m 2 / g, and the average mesopore diameter is 5.9nm.

[0047] The steps of preparing the coal-based solid waste sewage treatment material and using the coal-based solid waste sewage treatment material for sewage treatment include:

[0048] 1) mixing 85 parts of fly ash and 5 parts of biomass humic acid to obtain a first mixture;

[0049] 2) mixing the first mixture with 1 part of sodium thiosulfate to obtain a second mixture;

[0050] 3) Continue to mix the second mixture with 5 parts of gasified slag to obtain a coal-based solid waste sewage treatment material; the specific surface area of ​​the coal-based solid waste sewage treatment material is 21m 2 / g, and the average pore diameter of the mesopores is 9.6nm.

[0051] 4) The coal-based solid waste sewage treatment material obtained in step 3) is mixed with heavy metal sewage (the heavy metal content is shown in Table 2 below), wherein the amount of sewage is 25% based on the mass of the coal-based solid waste water treatment material; after standing for 5 days, a coal-based solid waste porous material is obtained.

[0052] Example 3

[0053] Coal-based solid waste sewage treatment materials, the raw materials of which include the following components, by weight: 75 parts of fly ash, 8 parts of gasified slag, 3 parts of sodium thiosulfate, and 6 parts of fulvic acid;

[0054] The pH value of the fly ash leaching solution is 11.6, and the calcium ion content is 251 mg / L; the water content of the gasified slag is 45%, the median particle size is 50 μm, and the specific surface area is 89 m 2 / g, and the average mesopore diameter is 7.2nm.

[0055] The steps of preparing the coal-based solid waste sewage treatment material and using the coal-based solid waste sewage treatment material for sewage treatment include:

[0056] 1) mixing 75 parts of fly ash and 6 parts of fulvic acid to obtain a first mixture;

[0057] 2) mixing the first mixture with 3 parts of sodium thiosulfate to obtain a second mixture;

[0058] 3) Continue to mix the second mixture with 8 parts of gasified slag to obtain a coal-based solid waste sewage treatment material; the specific surface area of ​​the coal-based solid waste sewage treatment material is 42m 2 / g, and the average mesopore diameter is 8.3nm.

[0059] 4) The coal-based solid waste sewage treatment material obtained in step 3) is mixed with heavy metal sewage (the heavy metal content is shown in Table 2 below), wherein the amount of sewage is 37% based on the mass of the coal-based solid waste water treatment material; after standing for 5 days, a coal-based solid waste porous material is obtained.

[0060] Example 4

[0061] Coal-based solid waste sewage treatment materials, the raw materials of which include the following components, by weight: 70 parts of fly ash, 15 parts of gasified slag, 1 part of sodium thiosulfate, and 5 parts of biomass humic acid;

[0062] The pH value of the fly ash leaching solution is 11.9, and the calcium ion content is 353 mg / L; the water content of the gasified slag is 31%, the median particle size is 37 μm, and the specific surface area is 106 m 2 / g, and the average pore diameter of the mesopores is 6.8nm.

[0063] The steps of preparing the coal-based solid waste sewage treatment material and using the coal-based solid waste sewage treatment material for sewage treatment include:

[0064] 1) mixing 70 parts of fly ash and 5 parts of biomass humic acid to obtain a first mixture;

[0065] 2) mixing the first mixture with 1 part of sodium thiosulfate to obtain a second mixture;

[0066] 3) Continue to mix the second mixture with 15 parts of gasified slag to obtain a coal-based solid waste sewage treatment material; the specific surface area of ​​the coal-based solid waste sewage treatment material is 82m 2 / g, and the average mesopore diameter is 8.3nm.

[0067] 4) The coal-based solid waste sewage treatment material obtained in step 3) is mixed with heavy metal sewage (the heavy metal content is shown in Table 2 below), wherein the amount of sewage is 40% based on the mass of the coal-based solid waste water treatment material; after standing for 5 days, a coal-based solid waste porous material is obtained.

[0068] Example 5

[0069] Coal-based solid waste sewage treatment materials, the raw materials of which include the following components, by weight: 70 parts of fly ash, 8 parts of gasified slag, 2 parts of sodium thiosulfate, and 5 parts of biomass humic acid;

[0070] The pH value of the fly ash leaching solution is 12.3, and the calcium ion content is 860 mg / L; the water content of the gasified slag is 45%, the median particle size is 26 μm, and the specific surface area is 213 m 2 / g, and the average mesopore diameter is 6.5nm.

[0071] The steps of preparing the coal-based solid waste sewage treatment material and using the coal-based solid waste sewage treatment material for sewage treatment include:

[0072] 1) mixing 70 parts of fly ash and 5 parts of biomass humic acid to obtain a first mixture;

[0073] 2) mixing the first mixture with 2 parts of sodium thiosulfate to obtain a second mixture;

[0074] 3) Continue to mix the second mixture with 8 parts of gasified slag to obtain a coal-based solid waste sewage treatment material; the specific surface area of ​​the coal-based solid waste sewage treatment material is 43m 2 / g, and the average mesopore diameter is 7.4nm.

[0075] 4) The coal-based solid waste sewage treatment material obtained in step 3) is mixed with heavy metal sewage (the heavy metal content is shown in Table 2 below), wherein the amount of sewage is 45% based on the mass of the coal-based solid waste water treatment material; after standing for 5 days, a coal-based solid waste porous material is obtained.

[0076] Example 6

[0077] Coal-based solid waste sewage treatment materials, the raw materials of which include the following components, by weight: 80 parts of fly ash, 15 parts of gasified slag, 4 parts of sodium thiosulfate, and 5 parts of biomass humic acid;

[0078] The pH value of the fly ash leaching solution is 11.3, and the calcium ion content is 215 mg / L; the water content of the gasified slag is 38%, the median particle size is 26 μm, and the specific surface area is 213 m 2 / g, and the average mesopore diameter is 6.5nm.

[0079] The steps of preparing the coal-based solid waste sewage treatment material and using the coal-based solid waste sewage treatment material for sewage treatment include:

[0080] 1) mixing 80 parts of fly ash and 5 parts of biomass humic acid to obtain a first mixture;

[0081] 2) mixing the first mixture with 4 parts of sodium thiosulfate to obtain a second mixture;

[0082] 3) Continue to mix the second mixture with 15 parts of gasified slag to obtain a coal-based solid waste sewage treatment material; the specific surface area of ​​the coal-based solid waste sewage treatment material is 80m 2 / g, and the average mesopore diameter is 8.3nm.

[0083] 4) The coal-based solid waste sewage treatment material obtained in step 3) is mixed with heavy metal sewage (the heavy metal content is shown in Table 2 below), wherein the amount of sewage is 45% based on the mass of the coal-based solid waste water treatment material; after standing for 5 days, a coal-based solid waste porous material is obtained.

[0084] Comparative Example 1

[0085] The process is carried out with reference to Example 1, except that the pH value of the fly ash leaching solution used is 8.6 and the calcium ion content is 230 mg / L.

[0086] Step 3) The specific surface area of ​​the coal-based solid waste sewage treatment material obtained is 78m 2 / g, and the average mesopore diameter is 7.5nm.

[0087] The remaining operations are consistent with those in Example 1.

[0088] Comparative Example 2

[0089] The process is carried out with reference to Example 1, except that the pH value of the fly ash leaching solution used is 11.1 and the calcium ion content is 93 mg / L.

[0090] Step 3) The specific surface area of ​​the coal-based solid waste sewage treatment material obtained is 75m 2 / g, and the average mesopore diameter is 7.2nm.

[0091] The remaining operations are consistent with those in Example 1.

[0092] Comparative Example 3

[0093] The same process as in Example 1 was performed except that no mineral source humic acid was added.

[0094] Step 3) The specific surface area of ​​the coal-based solid waste sewage treatment material obtained is 76m 2 / g, and the average mesopore diameter is 7.3nm.

[0095] The remaining operations are consistent with those in Example 1.

[0096] Comparative Example 4

[0097] The process is carried out in accordance with Example 1, except that no gasified slag is added.

[0098] Step 3) The specific surface area of ​​the coal-based solid waste sewage treatment material obtained is 3m 2 / g, no mesoporous structure.

[0099] The remaining operations are consistent with those in Example 1.

[0100] Comparative Example 5

[0101] The same procedure was followed as in Example 1, except that no sodium thiosulfate was added.

[0102] Step 3) The specific surface area of ​​the coal-based solid waste sewage treatment material obtained is 75m 2 / g, and the average mesopore diameter is 7.5nm.

[0103] The remaining operations are consistent with those in Example 1.

[0104] Comparative Example 6

[0105] The process is carried out with reference to Example 1, except that the sodium thiosulfate adding step in step 2) and the gasified slag adding step in step 3) are swapped.

[0106] Step 3) The specific surface area of ​​the coal-based solid waste sewage treatment material obtained is 75m 2 / g, and the average mesopore diameter is 7.5nm.

[0107] The remaining operations are consistent with those in Example 1.

[0108] The properties and raw material proportions of the coal-based solid waste sewage treatment materials obtained in Examples 1-6 and Comparative Examples 1-6 are shown in Table 1 below:

[0109] Table 1 Raw material dosage and performance of coal-based solid waste sewage treatment materials

[0110]

[0111]

[0112] The heavy metal contents in the sewage of Examples 1-6 and Comparative Examples 1-6 are shown in Table 2 below:

[0113] Among them, the content of heavy metal elements was measured using the method required by GB 8978-1996 "Integrated Wastewater Discharge Standard".

[0114] Table 2 Heavy metal content in sewage

[0115]

[0116] Performance test of coal-based solid waste porous materials

[0117] The coal-based solid waste porous materials prepared in Examples 1-6 and Comparative Examples 1-6 were subjected to performance tests, wherein the leachate of the coal-based solid waste porous materials was prepared by the method specified in HJ 557-2010 "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method", and the heavy metal element content was measured by the method required by GB 8978-1996 "Comprehensive Wastewater Discharge Standard". The results of the performance tests are shown in Table 3 below:

[0118] Table 3 Performance test results of coal-based solid waste porous materials

[0119]

[0120] From the results in the table, it can be seen that in Examples 1-6, the coal-based solid waste sewage treatment material prepared by mixing high alkalinity fly ash with gasification slag, sodium thiosulfate and humic acid in a certain proportion can solidify the heavy metals in the sewage and fix the heavy metals in the coal-based solid waste porous material. The heavy metal content of the leachate of the coal-based solid waste porous material obtained after fixation is extremely low. The pH value of the leachate of the fly ash used in the preparation of the coal-based solid waste sewage treatment material in Comparative Example 1 is low, the calcium ion content in the leachate of the fly ash used in the preparation of the coal-based solid waste sewage treatment material in Comparative Example 2 is low, no mineral source is added to humic acid when preparing the coal-based solid waste sewage treatment material in Comparative Example 3, no gasification slag is added when preparing the coal-based solid waste sewage treatment material in Comparative Example 4, no sodium thiosulfate is added when preparing the coal-based solid waste sewage treatment material in Comparative Example 5, and the sodium thiosulfate addition step in step 2) and the gasification slag addition step in step 3) are swapped in Comparative Example 6, and the other steps remain unchanged. The results showed that after the coal-based solid waste sewage treatment material prepared in the above comparative example was used to solidify the heavy metal sewage, the heavy metal content in the leachate of the obtained coal-based solid waste porous material was relatively high, and the results showed that the solidification effect was not good.

[0121] The above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.

Claims

1. A method for preparing coal-based solid waste sewage treatment materials, characterized in that: The coal-based solid waste sewage treatment material is prepared by using raw materials including the following components in parts by weight: 70-85 parts of fly ash, 5-15 parts of gasified slag, 1-5 parts of sodium thiosulfate, and 5-9 parts of humic acid; Wherein, the pH value of the fly ash leaching solution is greater than 11.0, and the calcium ion content is greater than or equal to 200 mg / L.

2. The method for preparing coal-based solid waste sewage treatment materials according to claim 1, characterized in that: The moisture content of the gasified slag is 15-45%; preferably, the gasified slag is gasified fine slag; more preferably, the median particle size of the gasified fine slag is 20-50 μm, and the specific surface area is 80-250 m 2 / g, and the average pore size of the mesopores is 2-10nm.

3. The method for preparing coal-based solid waste sewage treatment materials according to claim 1, characterized in that: The humic acid is one or more of mineral-derived humic acid, biomass humic acid and fulvic acid.

4. The method for preparing the coal-based solid waste sewage treatment material according to any one of claims 1 to 3, characterized in that: The specific surface area of ​​the coal-based solid waste sewage treatment material is 20-150m 2 / g, and it has a mesoporous structure with an average mesopore diameter of 5-50nm.

5. The method for preparing the coal-based solid waste sewage treatment material according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: 1) mixing fly ash and humic acid to obtain a first mixture; 2) mixing the first mixture and sodium thiosulfate to obtain a second mixture; 3) Continue to mix the second mixture with the gasified slag to obtain a coal-based solid waste sewage treatment material.

6. A coal-based solid waste sewage treatment material prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the coal-based solid waste sewage treatment material according to claim 6 in sewage treatment.

8. A method for treating sewage using the coal-based solid waste sewage treatment material according to claim 6, characterized in that: The steps include: The coal-based solid waste sewage treatment material and sewage are mixed and allowed to stand to form a coal-based solid waste porous material; based on the mass of the coal-based solid waste sewage treatment material, the amount of sewage used is 25-45%; Preferably, the sewage is heavy metal sewage.

9. The method according to claim 8, characterized in that The heavy metal is one or more of Cd, Cu, Mn, Pb and Zn.

10. The method according to claim 8, characterized in that The standing time is 1-7 days.

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