A method for co-disposal of waste incineration fly ash and landfill leachate membrane concentrate

Abstract

The application discloses a method for co-disposing waste incineration fly ash and landfill leachate membrane concentrated liquid. The application has simple preparation process, and the product prepared by the waste incineration fly ash and the landfill leachate membrane concentrated liquid is a stable static pressure brick product, no other soluble salt product is generated, and no waste liquid is generated. The chlorine content of the prepared static pressure brick is less than 0.2% at the lowest, the heavy metal pollutant leaching concentration is less than 0.01 mg / L at the lowest, and the strength of the static pressure brick is higher than 46.15 MPa at the highest.

Description

Technical Field

[0001] This invention belongs to the field of hazardous waste resource utilization, and in particular relates to a method for the co-processing of fly ash from waste incineration and leachate membrane concentrate. Background Technology

[0002] The incineration of municipal solid waste generates a large amount of fly ash, primarily from the precipitates of the flue gas purification system and the bottom ash settling at the bottom of the flue and chimney. Assuming fly ash generation accounts for 4% of the total waste incineration, it is projected that my country's fly ash production will reach 13 million tons annually by 2025. Fly ash also exhibits significant environmental hazards, containing not only high concentrations of heavy metal pollutants easily leached by water, but also organic carcinogens such as dioxins and furans. These pollutants in fly ash can contaminate water bodies and soil, thereby harming the health of plants, animals, and humans. Currently, the main technologies for treating and disposing of fly ash include: solidification and stabilization methods, resource recovery methods, chelation-stabilization coupled landfill, water washing and desalination coupled with cement kiln co-processing, and melt solidification treatment. Utilizing the inherent components of municipal solid waste incineration fly ash to prepare building brick materials is a typical resource recovery method, but some shortcomings remain in its practical application. Because fly ash from waste incineration contains large amounts of dioxins and heavy metals, these harmful substances may remain in the bricks during the production of non-fired bricks, posing a potential threat to the environment and human health. Therefore, the current production efficiency of non-fired bricks using waste incineration fly ash is relatively low. The production process requires the addition of large amounts of cementitious materials and chelating stabilizers to ensure efficient stabilization of heavy metals. Furthermore, the complex composition of waste incineration fly ash, with its high content of soluble chlorides, not only causes excessive chloride content in the bricks but also inhibits the hydration and curing process of the cementitious materials, affecting the brick strength and making the building brick materials unable to meet relevant environmental standards and requirements.

[0003] Landfill leachate membrane concentrate contains a large amount of inorganic salts and organic pollutants, making its treatment challenging. Common disposal methods include landfill, incineration, and reuse, but these methods all have certain problems. They require significant energy and financial investment, and the treated products often fail to meet environmental protection requirements, thus hindering large-scale application. Currently, in waste-to-energy plants, landfill leachate membrane concentrate is incinerated by being injected back into the furnace. However, the high water content of landfill leachate membrane concentrate, when injected into the furnace, not only severely impacts the furnace's calorific value and significantly increases energy consumption, but its inorganic salt content also tends to reduce the furnace's lifespan.

[0004] Therefore, the co-processing of waste incineration fly ash and waste leachate membrane concentrate during the preparation of brick materials using waste incineration fly ash is particularly crucial, and the research and development of related technologies has certain industry significance. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method for preparing static pressure bricks through the co-processing of fly ash from waste incineration and leachate membrane concentrate.

[0006] Technical solution: The method for co-processing fly ash from waste incineration and leachate membrane concentrate of the present invention includes the following steps:

[0007] (1) Mix phosphate, fly ash and waste incineration fly ash, stir evenly to obtain phosphoric coal fly ash;

[0008] (2) Mix the adsorption powder, domestic sludge and phosphorus coal fly ash, stir evenly to obtain phosphorus coal sludge fly ash adsorption mixed powder.

[0009] (3) Mix the landfill leachate membrane concentrate and the phosphorus coal slime fly ash adsorption mixture powder, and stir until the phosphate in the phosphorus coal fly ash adsorption mixture powder is completely dissolved to obtain a coarse slurry.

[0010] (4) Seal the coarse pulp and let it stand for aging to obtain anaerobic pulp;

[0011] (5) Continuous aeration of anaerobic slurry yields aerobic slurry;

[0012] (6) Dry the aerobic slurry and calcine it to obtain the slag as active detoxification slag;

[0013] (7) Grind the active detoxification residue into powder, add water and stir evenly, put it into a mold to form bricks, and cure it naturally to obtain static pressure brick finished products.

[0014] In step (1), the mass ratio of phosphate, fly ash, and waste incineration fly ash is 0.5-7.5:60-120:100.

[0015] In step (1), the phosphate is any one or a mixture of sodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, and sodium hexametaphosphate.

[0016] In step (2), the mass ratio of adsorbent powder, domestic sludge and fly ash of phosphate coal is 20-40:20-60:100.

[0017] The adsorbent powder mentioned in step (2) is any one or a mixture of zeolite powder, expanded perlite powder, expanded vermiculite powder, and sepiolite powder.

[0018] In step (3), the liquid-solid ratio of the landfill leachate membrane concentrate and the phosphorus coal slime fly ash adsorption mixture is 0.5-1.5:100mL / g.

[0019] The aging time mentioned in step (4) is 14 to 28 days.

[0020] The continuous aeration time mentioned in step (5) is 4 to 16 days.

[0021] The calcination time in step (6) is 0.5 to 4.5 hours; the calcination temperature is 800 to 1200℃.

[0022] In step (7), the liquid-to-solid ratio of water and active detoxification residue is 0.4-0.6:1 mL / g; the curing time is 7-28 days.

[0023] Reaction Mechanism: When mixed with landfill leachate membrane concentrate and phosphate-coal sludge fly ash adsorption mixture, ammonium ions in the leachate react with phosphate ions and calcium, aluminum, silicon, and iron in the phosphate-coal sludge fly ash adsorption mixture to form a gel-like precipitate. This gel-like precipitate effectively adsorbs heavy metal pollutants and chlorides from the phosphate-coal sludge fly ash adsorption mixture. After sealing the coarse slurry and allowing it to settle and age, the anaerobic bacteria in the leachate membrane concentrate and the microorganisms in the sewage sludge use the adsorption mixture as a bioreactor. Through ion exchange and electron transfer, they decompose complex organic matter, producing small-molecule organic acids. These small-molecule organic acids can simultaneously adsorb onto the adsorption powder and the gel-like precipitate, achieving carboxylation and further enhancing their adsorption capacity for heavy metals and inorganic salts. Simultaneously, the small-molecule organic acids can also combine with dissolved calcium ions in the mixed slurry to form organic calcium precipitates. Continuous aeration of the anaerobic slurry allows small organic molecules dissolved in the slurry and adsorbed onto the surface of the adsorbent powder and gel precipitates to be further oxidized into carbon dioxide during the aerobic reaction. This carbon dioxide dissolves in the alkaline slurry to form carbonate ions, which then react with dissolved calcium ions to form calcium carbonate precipitates. Aerobic microorganisms can also enhance the release of aluminum sources from the adsorbent mixture of phosphorus-coal slurry and fly ash by synthesizing cellular material and decomposing hydrogen ions, thereby further strengthening the gelling properties between precipitates. During calcination, residual organic matter in the aerobic slurry can be further mineralized and decomposed into carbon dioxide gas and thermal steam. Residual ammonia nitrogen in the aerobic slurry can inhibit the formation of nitrogen oxides. Simultaneously, the decomposition products from the thermal decomposition of organic calcium, calcium carbonate, and gel precipitates in the aerobic slurry further promote the reaction between inorganic salts in the aerobic slurry and aluminates and aluminosilicates in the adsorbent powder and fly ash, as well as silica in the sewage sludge, generating stable residues and activated detoxification residues that are a mixture of gelling and hydrating active materials. The active detoxifying residue is ground into powder, mixed with water, and hydration and polymerization reactions occur during the stirring process. Through the hardening stage, a static pressure brick product with a certain strength is formed.

[0024] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: The preparation process of this invention is simple, and the products prepared using waste incineration fly ash and leachate membrane concentrate are both stable static pressure bricks, with no other soluble salt products generated and no waste liquid produced. The prepared static pressure bricks have a minimum chlorine content of less than 0.2%, a minimum heavy metal pollutant leaching concentration of less than 0.01 mg / L, and a maximum strength of more than 46.15 MPa. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0027] Waste incineration fly ash: taken from the Changshu No. 2 Municipal Solid Waste Incineration Power Plant in Jiangsu Province, mainly including 36.2% CaO, 23.9% Cl, 11.0% SO3, 11.6% Na2O, 6.33% K2O, 4.38% SiO2, 1.40% Fe2O3, 1.25% Al2O3 and other components (unavoidable impurities and loss on ignition);

[0028] Fly ash: sourced from Huaneng International Power Development Corporation Taicang Power Plant, mainly comprising 43.21% SiO2, 27.08% Al2O3, 15.62% Fe2O3, 6.58% CaO, 3.42% TiO2, 1.43% SO3, 1.04% K2O, 0.63% Na2O and other components (unavoidable impurities and loss on ignition);

[0029] Expanded perlite powder: The expanded perlite powder in this invention comes from Henan Xinyang Simuda Technology Co., Ltd. The expanded perlite powder is composed of 81.38% SiO2, 11.52% Al2O3, 2.41% K2O, 1.58% MgO, 1.48% TiO2 and other components (unavoidable impurities and loss on ignition);

[0030] Expanded vermiculite powder: The expanded vermiculite powder in this invention comes from Hebei Luefeng New Material Technology Co., Ltd. The chemical composition of the expanded vermiculite powder includes: 39.45% SiO2, 16.78% Al2O3, 3.14% K2O, 18.59% MgO, 1.23% TiO2, 4.06% CaO and other components (unavoidable impurities and loss on ignition);

[0031] Domestic sewage sludge: Domestic sewage sludge (municipal sludge) is taken from the sewage treatment plant in Changshu Southeast Development Zone. Its main chemical components include: 64.17% SiO2, 13.56% Al2O3, 4.86% Fe2O3, 3.75% P2O5, 2.34% CaO and other components (loss on ignition and other unavoidable impurities).

[0032] Sepiolite: sourced from Hongyang Sepiolite Co., Ltd., Neixiang County; its general formula is (Si... 12 Mg8O 30 (OH)4(OH2)4·8H2O;

[0033] Zeolite powder: from Tianmen Hengchang Chemical Co., Ltd., CAS No. 1327-44-2, also known as 4A zeolite, purity 99%, molecular formula Na 12 Al 12 Si 12 O 48 ·27H2O;

[0034] Landfill leachate membrane concentrate: The raw landfill leachate was sourced from Wuhu Oasis Environmental Energy Co., Ltd., with a COD concentration of 4678 mg / L, a total phosphorus concentration of 126 mg / L, and an ammonia nitrogen concentration of 592 mg / L. The landfill leachate membrane concentrate is obtained by concentrating the raw leachate through a membrane to 0.15–0.25 times its original volume.

[0035] Example 1: Effect of the mass ratio of phosphate, fly ash, and waste incineration fly ash on the performance of the prepared statically pressed bricks

[0036] According to mass ratios of 0.25:60:100, 0.3:60:100, 0.4:60:100, 0.5:30:100, 0.5:40:100, 0.5:50:100, 0.5:60:100, 4:60:100, 7.5:60:100, 0.5:90:100, 4:90:100, 7.5:90:100, 0.5: Phosphate, fly ash, and waste incineration fly ash were mixed in ratios of 120:100, 4:120:100, 7.5:120:100, 7.5:130:100, 7.5:140:100, 7.5:150:100, 8:120:100, 8.5:120:100, and 9:120:100, and stirred evenly to obtain phosphate-coal fly ash, wherein the phosphate is sodium phosphate. Adsorption powder, domestic sewage sludge, and phosphate-coal fly ash were mixed in a mass ratio of 20:20:100, and stirred evenly to obtain phosphate-coal sludge fly ash adsorption mixture powder, wherein the adsorption powder is zeolite powder. Landfill leachate membrane concentrate (concentrated to 0.2 times its original volume) and phosphate-coal sludge fly ash adsorption mixture powder were mixed in a liquid-solid ratio of 0.5:100 mL / g, and stirred until the phosphate in the phosphate-coal fly ash adsorption mixture powder was completely dissolved to obtain a coarse slurry. The coarse slurry was sealed and allowed to stand for 14 days to obtain anaerobic slurry. The anaerobic slurry was continuously aerated for 4 days to obtain aerobic slurry. The aerobic slurry was dried and then calcined in a calcining furnace for 0.5 hours to obtain active detoxifying slag, with the calcination temperature at 800℃. The active detoxifying slag was ground into powder and mixed with water at a liquid-to-solid ratio of 0.4:1 mL / g, stirred evenly, poured into molds to form bricks, and naturally cured for 7 days to obtain statically pressed bricks.

[0037] Compressive strength test: The compressive strength test of the static pressure bricks prepared by this invention is carried out in accordance with the standard of "Solid Concrete Bricks" (GB / T21144-2007).

[0038] Leachate preparation: The leachate for preparing statically pressed bricks in this invention is prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557-2010).

[0039] Determination of heavy metal ion concentrations in the leachate of statically pressed bricks: The concentrations of lead and cadmium in the leachate were determined according to the standards specified in "Determination of 32 Elements in Water - Inductively Coupled Plasma Atomic Emission Spectrometry" (HJ 776-2015). The total chromium in the leachate of statically pressed bricks was determined according to the standards specified in "Determination of Chromium in Water - Flame Atomic Absorption Spectrophotometry" (HJ 757-2015).

[0040] Chlorine content determination: The chlorine content in statically pressed bricks was determined according to the "Building Sand" standard (GB / T 14684-2011). The results are shown in Table 1.

[0041] Table 1. Effects of mass ratios of phosphate, fly ash, and waste incineration fly ash on the properties of the prepared static pressure bricks.

[0042]

[0043]

[0044] As shown in Table 1, when the mass ratio of phosphate, fly ash, and waste incineration fly ash is less than 0.5:60:100 (as shown in Table 1, when the mass ratio of phosphate, fly ash, and waste incineration fly ash is 0.4:60:100, 0.3:60:100, 0.25:60:100, 0.5:50:100, 0.5:40:100, 0.5:30:100, and even lower ratios not listed in Table 1), less phosphate and fly ash are added. The amount of gel-like precipitate generated during the adsorption of mixed leachate membrane concentrate and phosphate-coal slurry fly ash is reduced, and the adsorption effect of heavy metals and chlorides becomes worse. As a result, the leaching concentration of heavy metals and chloride content of the prepared static pressure bricks increases significantly with the decrease of the mass ratio of phosphate, fly ash, and waste incineration fly ash, while the uniaxial compressive strength of the prepared static pressure bricks decreases significantly with the decrease of the mass ratio of phosphate, fly ash, and waste incineration fly ash. When the mass ratio of phosphate, fly ash, and waste incineration fly ash is 0.5–7.5:60–120:100 (as shown in Table 1, where the mass ratios are 0.5:60:100, 4:60:100, 7.5:60:100, 0.5:90:100, 4:90:100, 7.5:90:100, 0.5:120:100, 4:120:100, and 7.5:120:100), the mixed leachate membrane concentrate and the phosphate-coal sludge fly ash adsorption mixture will react with phosphate ions and calcium, aluminum, silicon, and iron in the phosphate-coal sludge fly ash adsorption mixture during the mixing process to form a gel-like precipitate. This gel-like precipitate can effectively adsorb heavy metal pollutants and chlorides in the phosphate-coal sludge fly ash adsorption mixture. Ultimately, the prepared statically pressed bricks all had a chlorine content of less than 0.3%, a heavy metal leaching concentration of less than 0.1 mg / L, and a strength of more than 30 MPa. When the mass ratio of phosphate, fly ash, and waste incineration fly ash is greater than 7.5:120:100 (as shown in Table 1, the mass ratios of phosphate, fly ash, and waste incineration fly ash are 7.5:130:100, 7.5:140:100, 7.5:150:100, 8:120:100, 8.5:120:100, 9:120:100, and higher ratios not listed in Table 1), excessive addition of phosphate and fly ash leads to an imbalance in the material reaction. This results in a significant increase in the leaching concentration of heavy metals and the chlorine content of the prepared static pressure bricks as the mass ratio of phosphate, fly ash, and waste incineration fly ash further increases, while the uniaxial compressive strength of the prepared static pressure bricks significantly decreases as the mass ratio of phosphate, fly ash, and waste incineration fly ash further increases.

[0045] Therefore, in general, a mass ratio of phosphate, fly ash, and waste incineration fly ash of 0.5–7.5:60–120:100 is most conducive to improving the performance of the prepared static pressure bricks.

[0046] Example 2: Effect of the mass ratio of adsorbent powder, domestic sludge, and fly ash from phosphate coal on the performance of the prepared statically pressed bricks

[0047] Phosphate, fly ash, and waste incineration fly ash are mixed in a mass ratio of 7.5:120:100, stirred evenly, to obtain phosphoric acid coal fly ash, wherein the phosphate is disodium hydrogen phosphate. Phosphate is then mixed in the following mass ratios: 12.5:20:100, 15:20:100, 17.5:20:100, 20:12.5:100, 20:15:100, 20:17.5:100, 20:20:100, 30:20:100, 40:20:100, 20:40:100, 30:40:100, 40:40:100, 20: Mixed adsorption powders, sewage sludge, and phosphate coal fly ash were prepared in ratios of 60:100, 30:60:100, 40:60:100, 40:65:100, 40:70:100, 40:75:100, 45:60:100, 50:60:100, and 55:60:100. These mixtures were stirred until homogeneous to obtain a phosphate coal sludge fly ash adsorption mixture, in which the adsorption powder was expanded perlite powder. Landfill leachate membrane concentrate (concentrated to 0.2 times its original volume) and the phosphate coal sludge fly ash adsorption mixture were mixed at a liquid-to-solid ratio of 1:100 mL / g and stirred until the phosphates in the mixture were completely dissolved to obtain a coarse slurry. The coarse slurry was sealed and allowed to stand for 21 days to obtain an anaerobic slurry. The anaerobic slurry was continuously aerated for 10 days to obtain an aerobic slurry. The aerobic slurry was dried and then calcined in a calcining furnace for 2.5 hours to obtain activated detoxifying slag, with the calcination temperature at 1000℃. The activated detoxifying slag was ground into powder and mixed with water at a liquid-to-solid ratio of 0.5:1 mL / g, stirred evenly, poured into molds to form bricks, and naturally cured for 17.5 days to obtain the statically pressed brick product. Compressive strength test: The compressive strength test of the statically pressed bricks prepared in this invention was performed in accordance with the standard of "Solid Concrete Bricks" (GB / T 21144-2007).

[0048] The preparation of the leachate, the determination of the concentration of heavy metal ions in the leachate of the statically pressed bricks, and the determination of the chlorine content were all the same as in Example 1. The results of this experiment are shown in Table 2.

[0049] Table 2. Effect of mass ratio of adsorbent powder, sewage sludge, and fly ash from phosphate coal on the performance of the prepared static pressure bricks.

[0050]

[0051]

[0052] As shown in Table 2, when the mass ratio of adsorbent powder, domestic sludge, and fly ash from phosphate coal is less than 20:20:100 (such as in Table 2, when the mass ratio of adsorbent powder, domestic sludge, and fly ash from phosphate coal is 17.5:20:100, 15:20:100, 12.5:20:100, 20:17.5:100, 20:15:100, 20:12.5:100, and lower ratios not listed in Table 2), less adsorbent powder and domestic sludge need to be added. During the process of mixing landfill leachate membrane concentrate and phosphorus coal sludge fly ash adsorption mixture powder, the amount of gel-like precipitate generated decreased, and the adsorption effect of heavy metals and chloride salts deteriorated. At the same time, the gel activation was insufficient during the anaerobic and aerobic fermentation process, which led to a significant increase in the leaching concentration of heavy metals and chloride content of the prepared static pressure bricks as the mass ratio of adsorption powder, domestic sludge and phosphorus coal fly ash decreased. Meanwhile, the uniaxial compressive strength of the prepared static pressure bricks decreased significantly as the mass ratio of adsorption powder, domestic sludge and phosphorus coal fly ash decreased. When the mass ratio of adsorbent powder, sewage sludge, and fly ash from phosphate coal is 20–40:20–60:100 (as shown in Table 2, where the mass ratios are 20:20:100, 30:20:100, 40:20:100, 20:40:100, 30:40:100, 40:40:100, 20:60:100, 30:60:100, and 40:60:100), the mixed leachate membrane concentrate and fly ash adsorbent powder from phosphate coal sludge can react with phosphate ions and calcium, aluminum, silicon, and iron in the fly ash adsorbent powder during the mixing process to form a gel-like precipitate. This gel-like precipitate can effectively adsorb heavy metal pollutants and chloride salts from the fly ash adsorbent powder. During the sealing and aging process of the coarse slurry, the anaerobic bacteria in the leachate membrane concentrate and the microorganisms in the sewage sludge use the adsorption mixture as a bioreactor. Through ion exchange and electron transfer, they decompose complex organic matter, producing small-molecule organic acids. These small-molecule organic acids can be simultaneously adsorbed onto the adsorbent powder and gel-like precipitates, achieving carboxylation and further enhancing their adsorption capacity for heavy metals and inorganic salts. Simultaneously, the small-molecule organic acids can combine with dissolved calcium ions in the slurry to form organic calcium precipitates. Continuous aeration of the anaerobic slurry further oxidizes the small-molecule organic matter dissolved in the slurry and adsorbed on the surface of the adsorbent powder and gel precipitates into carbon dioxide during the aerobic reaction. This carbon dioxide dissolves in the alkaline slurry to form carbonate ions, which then react with dissolved calcium ions to form calcium carbonate precipitates. Furthermore, aerobic microorganisms can enhance the release of aluminum sources from the adsorbent mixture of phosphorus coal slurry and fly ash by synthesizing cellular material and decomposing hydrogen ions, thereby further strengthening the gelling properties of the precipitates. Ultimately, the prepared statically pressed bricks all had a chlorine content of less than 0.2%, a heavy metal leaching concentration of less than 0.01 mg / L, and a strength of more than 37 MPa.When the mass ratio of adsorbent powder, domestic sludge, and fly ash from phosphate coal is greater than 40:60:100 (as shown in Table 2, the mass ratios of adsorbent powder, domestic sludge, and fly ash from phosphate coal are 40:65:100, 40:70:100, 40:75:100, 45:60:100, 50:60:100, 55:60:100, and higher ratios not listed in Table 2), the excessive addition of adsorbent powder and domestic sludge leads to an imbalance in the material reaction. This results in a significant increase in the leaching concentration of heavy metals and the chlorine content of the prepared static pressure bricks as the mass ratio of adsorbent powder, domestic sludge, and fly ash from phosphate coal increases further, while the uniaxial compressive strength of the prepared static pressure bricks decreases significantly as the mass ratio of adsorbent powder, domestic sludge, and fly ash from phosphate coal increases further.

[0053] Therefore, in general, the mass ratio of adsorbent powder, domestic sludge and fly ash from phosphorus coal is 20-40:20-60:100, which is most conducive to improving the performance of the prepared static pressure bricks.

[0054] Example 3: Effect of the liquid-to-solid ratio of the mixed powder of landfill leachate membrane concentrate and phosphorus coal slime fly ash on the performance of the prepared static pressure bricks

[0055] Phosphate, fly ash, and waste incineration fly ash were mixed in a mass ratio of 7.5:120:100, and stirred evenly to obtain phosphate-coal fly ash, wherein the phosphate was sodium dihydrogen phosphate. Adsorption powder, sewage sludge, and phosphate-coal fly ash were mixed in a mass ratio of 40:60:100, and stirred evenly to obtain phosphate-coal sludge fly ash adsorption mixture powder, wherein the adsorption powder was expanded vermiculite powder. A coarse slurry was prepared by mixing landfill leachate membrane concentrate (concentrated to 0.2 times its original volume) with phosphorus-coal slurry fly ash adsorption mixture powder at liquid-to-solid ratios of 0.35:100mL / g, 0.4:100mL / g, 0.45:100mL / g, 0.5:100mL / g, 1:100mL / g, 1.5:100mL / g, 1.75:100mL / g, 2.0:100mL / g, and 2.25:100mL / g. The mixture was stirred until the phosphate in the phosphorus-coal slurry fly ash adsorption mixture powder was completely dissolved. The coarse slurry was sealed and allowed to stand for 28 days to obtain anaerobic slurry. The anaerobic slurry was continuously aerated for 16 days to obtain aerobic slurry. The aerobic slurry was dried and then calcined in a calciner for 4.5 hours to obtain activated detoxification slag, with the calcination temperature being 1200℃. The active detoxifying residue is ground into powder, and water and active detoxifying residue are mixed at a liquid-solid ratio of 0.6:1mL / g. The mixture is stirred evenly, poured into a mold to form bricks, and naturally cured for 28 days to obtain statically pressed brick products.

[0056] The preparation of the leachate, the determination of the concentration of heavy metal ions in the leachate of the statically pressed bricks, and the determination of the chlorine content were all the same as in Example 1. The results of this experiment are shown in Table 3.

[0057] Table 3. Effect of the liquid-solid ratio of the mixed powder of landfill leachate membrane concentrate and phosphate coal slime fly ash on the performance of the prepared static pressure bricks.

[0058]

[0059]

[0060] As shown in Table 3, when the liquid-to-solid ratio of the mixed powder of landfill leachate membrane concentrate and phosphorus coal sludge fly ash is less than 0.5:100 mL / g (as shown in Table 3, when the liquid-to-solid ratio of the mixed powder of landfill leachate membrane concentrate and phosphorus coal sludge fly ash is 0.45:100 mL / g, 0.4:100 mL / g, 0.35:100 mL / g, and lower ratios not listed in Table 3), less landfill leachate membrane concentrate is added, and the mixture of landfill leachate membrane concentrate and phosphorus coal sludge fly ash adsorption powder... During the powdering process, the amount of gel-like precipitate generated decreased, and the adsorption effect of heavy metals and chloride salts deteriorated. At the same time, the gel activation was insufficient during the anaerobic and aerobic fermentation process, and the slag formation and material activation effect during the calcination process deteriorated. As a result, the leaching concentration of heavy metals and the chloride content of the prepared static pressure bricks increased significantly with the decrease of the liquid-solid ratio of the mixed powder adsorbed by the landfill leachate membrane concentrate and the phosphorus coal slime fly ash. Meanwhile, the uniaxial compressive strength of the prepared static pressure bricks decreased significantly with the decrease of the liquid-solid ratio of the mixed powder adsorbed by the landfill leachate membrane concentrate and the phosphorus coal slime fly ash. When the liquid-to-solid ratio of the leachate membrane concentrate and the phosphorus-coal sludge fly ash adsorption mixture is 0.5–1.5:100 mL / g (as shown in Table 3, where the liquid-to-solid ratios are 0.5:100 mL / g, 1:100 mL / g, and 1.5:100 mL / g), during mixing, ammonium ions in the leachate can combine with phosphate ions and calcium, aluminum, silicon, and iron in the phosphorus-coal sludge fly ash adsorption mixture to form a gel-like precipitate. This gel-like precipitate effectively adsorbs heavy metal pollutants and chlorides from the phosphorus-coal sludge fly ash adsorption mixture. After sealing the coarse slurry and allowing it to settle and age, the anaerobic bacteria in the leachate membrane concentrate and the microorganisms in the sewage sludge use the adsorption mixture as a bioreactor. Through ion exchange and electron transfer, they decompose complex organic matter, producing small-molecule organic acids. Small-molecule organic acids can be simultaneously adsorbed onto the adsorbent powder and gel-like precipitate, achieving carboxylation of the adsorbent powder and gel-like precipitate, thereby further enhancing their adsorption capacity for heavy metals and inorganic salts. Simultaneously, small-molecule organic acids can combine with dissolved calcium ions in the mixed slurry to form organic calcium precipitates. During continuous aeration of the anaerobic slurry, small-molecule organic matter dissolved in the slurry and adsorbed on the surface of the adsorbent powder and gel-like precipitate during the aerobic reaction process is further oxidized into carbon dioxide. This carbon dioxide dissolves in the alkaline slurry to form carbonate ions, which further react with dissolved calcium ions to form calcium carbonate precipitates. Aerobic microorganisms can also enhance the release of aluminum sources from the adsorbed mixed powder of phosphorus coal slurry fly ash by synthesizing cellular material and decomposing hydrogen ions, thereby further enhancing the gelling properties between precipitates. During calcination, residual organic matter in the aerobic slurry can be further mineralized and decomposed into carbon dioxide gas and hot steam. Residual ammonia nitrogen in the aerobic slurry can inhibit the formation of nitrogen oxides.Meanwhile, the decomposition products of organic calcium, calcium carbonate, and gel-like precipitates in the aerobic slurry, due to thermal decomposition, further promote the reaction between inorganic salts in the aerobic slurry and aluminates and aluminosilicates in the adsorbent powder and fly ash, as well as silica in the sewage sludge, generating stable residues and active detoxification residues that are a mixture of gelling and hydration active materials. Ultimately, the prepared statically pressed bricks all had a chlorine content of less than 0.1%, a heavy metal leaching concentration of less than 0.01 mg / L, and a statically pressed brick strength of more than 42 MPa. When the liquid-to-solid ratio of the leachate membrane concentrate and the adsorbent mixture of coal sludge and fly ash is greater than 1.5:100 mL / g (as shown in Table 3, when the liquid-to-solid ratio of the leachate membrane concentrate and the adsorbent mixture of coal sludge and fly ash is 1.75:100 mL / g, 2.0:100 mL / g, 2.25:100 mL / g, and higher ratios not listed in Table 3), the excessive addition of adsorbent powder and domestic sludge leads to an imbalance in the material reaction. As a result, the leaching concentration of heavy metals and the chlorine content of the prepared static pressure bricks increase significantly with the further increase of the liquid-to-solid ratio of the leachate membrane concentrate and the adsorbent mixture of coal sludge and fly ash, while the uniaxial compressive strength of the prepared static pressure bricks decreases significantly with the further increase of the liquid-to-solid ratio of the leachate membrane concentrate and the adsorbent mixture of coal sludge and fly ash.

[0061] Therefore, in general, a liquid-to-solid ratio of 0.5–1.5:100 mL / g for the mixed powder of landfill leachate membrane concentrate and phosphorus coal slime fly ash is most conducive to improving the performance of the prepared static pressure bricks.

[0062] Example 4: Effect of phosphate type on the properties of the prepared statically pressed bricks

[0063] Phosphate, fly ash, and waste incineration fly ash were mixed in a mass ratio of 7.5:120:100 and stirred evenly to obtain phosphate-coal fly ash. The phosphate was any one of sodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, or sodium hexametaphosphate. Adsorption powder, sewage sludge, and phosphate-coal fly ash were mixed in a mass ratio of 40:60:100 and stirred evenly to obtain phosphate-coal sludge fly ash adsorption mixture powder, wherein the adsorption powder was sepiolite powder. Leachate membrane concentrate (concentrated to 0.2 times its original volume) and phosphate-coal sludge fly ash adsorption mixture powder were mixed in a liquid-to-solid ratio of 1.5:100 mL / g and stirred until the phosphate in the phosphate-coal ash adsorption mixture powder was completely dissolved to obtain a coarse slurry. The coarse slurry was sealed and allowed to stand for 28 days to obtain an anaerobic slurry. The anaerobic slurry was continuously aerated for 16 days to obtain an aerobic slurry. The aerobic slurry is dried and then calcined in a calcining furnace for 4.5 hours to obtain active detoxifying slag, with the calcination temperature at 1200℃. The active detoxifying slag is ground into powder and mixed with water at a liquid-solid ratio of 0.6:1 mL / g. The mixture is stirred evenly, poured into molds to form bricks, and naturally cured for 28 days to obtain statically pressed bricks.

[0064] The preparation of the leachate, the determination of the concentration of heavy metal ions in the leachate of the statically pressed bricks, and the determination of the chlorine content were all the same as in Example 1. The results of this experiment are shown in Table 4.

[0065] Table 4. Effect of phosphate type on the properties of the prepared statically pressed bricks

[0066]

[0067]

[0068] As shown in Table 4, when the phosphate is any one of sodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, or sodium hexametaphosphate, the static pressure bricks prepared have similar properties with no significant differences.

[0069] The effect of different processes on the properties of the prepared statically pressed bricks

[0070] The process of this invention is as follows: Phosphate, fly ash, and waste incineration fly ash are mixed in a mass ratio of 7.5:120:100, stirred evenly to obtain phosphate-coal fly ash, wherein the phosphate is sodium phosphate. Adsorption powder, sewage sludge, and phosphate-coal fly ash are mixed in a mass ratio of 40:60:100, stirred evenly to obtain phosphate-coal sludge fly ash adsorption mixture powder, wherein the adsorption powder is sepiolite powder. Leachate membrane concentrate (concentrated to 0.2 times its original volume) and phosphate-coal sludge fly ash adsorption mixture powder are mixed in a liquid-to-solid ratio of 1.5:100 mL / g, stirred until the phosphate in the phosphate-coal fly ash adsorption mixture powder is completely dissolved to obtain a coarse slurry. The coarse slurry is sealed and allowed to stand for 28 days to obtain an anaerobic slurry. The anaerobic slurry is continuously aerated for 16 days to obtain an aerobic slurry. The aerobic slurry is dried and then calcined in a calcining furnace for 4.5 hours to obtain activated detoxification slag, wherein the calcination temperature is 1200℃. The active detoxifying residue is ground into powder, and water and active detoxifying residue are mixed at a liquid-solid ratio of 0.6:1mL / g. The mixture is stirred evenly, poured into a mold to form bricks, and naturally cured for 28 days to obtain statically pressed brick products.

[0071] Comparative Process 1: Phosphate, fly ash, and waste incineration fly ash were mixed in a mass ratio of 7.5:120:100, stirred evenly, to obtain phosphate-coal fly ash, where the phosphate was sodium phosphate. Adsorption powder, sewage sludge, and phosphate-coal fly ash were mixed in a mass ratio of 40:60:100, stirred evenly, to obtain phosphate-coal sludge fly ash adsorption mixture powder, where the adsorption powder was sepiolite powder. Water and phosphate-coal sludge fly ash adsorption mixture powder were mixed in a liquid-solid ratio of 1.5:100 mL / g, stirred until the phosphate in the phosphate-coal sludge fly ash adsorption mixture powder was completely dissolved, to obtain a coarse slurry. The coarse slurry was sealed and allowed to stand for 28 days to age, to obtain an anaerobic slurry. The anaerobic slurry was continuously aerated for 16 days to obtain an aerobic slurry. The aerobic slurry was dried and then calcined in a calcining furnace for 4.5 hours, to obtain activated detoxification slag, where the calcination temperature was 1200℃. The active detoxifying residue is ground into powder, and water and active detoxifying residue are mixed at a liquid-solid ratio of 0.6:1mL / g. The mixture is stirred evenly, poured into a mold to form bricks, and naturally cured for 28 days to obtain statically pressed brick products.

[0072] Comparative Process 2: Phosphate, fly ash, and waste incineration fly ash were mixed in a mass ratio of 7.5:120:100, stirred evenly, to obtain phosphate-coal fly ash, wherein the phosphate was sodium phosphate. Adsorption powder, sewage sludge, and phosphate-coal fly ash were mixed in a mass ratio of 40:60:100, stirred evenly, to obtain phosphate-coal sludge fly ash adsorption mixture powder, wherein the adsorption powder was sepiolite powder. Leachate membrane concentrate (concentrated to 0.2 times its original volume) and phosphate-coal sludge fly ash adsorption mixture powder were mixed in a liquid-solid ratio of 1.5:100 mL / g, stirred until the phosphate in the phosphate-coal fly ash adsorption mixture powder was completely dissolved, to obtain a coarse slurry. The coarse slurry was dried, and then calcined in a calcining furnace for 4.5 hours to obtain activated detoxification slag, wherein the calcination temperature was 1200℃. The active detoxifying residue is ground into powder, and water and active detoxifying residue are mixed at a liquid-solid ratio of 0.6:1mL / g. The mixture is stirred evenly, poured into a mold to form bricks, and naturally cured for 28 days to obtain statically pressed brick products.

[0073] The preparation of the leachate, the determination of the concentration of heavy metal ions in the leachate of the statically pressed bricks, and the determination of the chlorine content were all the same as in Example 1. The results of this experiment are shown in Table 5.

[0074] Table 5. Effects of different processes on the properties of the prepared static pressure bricks.

[0075]

[0076] As shown in Table 5, the static pressure bricks prepared by the process of the present invention have significantly better performance than comparative processes 1 and 2.

Claims

1. A method for the co-treatment of fly ash from waste incineration and leachate membrane concentrate, characterized in that, Includes the following steps: (1) Mix phosphate, fly ash and waste incineration fly ash, stir evenly to obtain phosphoric coal fly ash; (2) Mix the adsorption powder, domestic sludge and phosphorus fly ash, stir evenly to obtain phosphorus fly ash adsorption mixed powder; The mass ratio of the adsorbent powder, sewage sludge, and fly ash from phosphate coal is 20~40:20~60:100; (3) Mix the leachate membrane concentrate and the phosphorus coal slurry fly ash adsorption mixture powder, and stir until the phosphate in the phosphorus coal fly ash adsorption mixture powder is completely dissolved to obtain the coarse slurry. (4) Seal the coarse pulp and let it stand for aging to obtain anaerobic pulp; (5) Continuous aeration of the anaerobic slurry yields an aerobic slurry; (6) The aerobic slurry is dried and calcined to obtain active detoxification slag; (7) Grind the active detoxification residue into powder, add water and stir evenly, put it into a mold to form bricks, and cure it naturally to obtain static pressure brick finished products.

2. The method for co-processing fly ash from waste incineration and leachate membrane concentrate according to claim 1, characterized in that, The mass ratio of phosphate, fly ash and waste incineration fly ash mentioned in step (1) is 0.5~7.5:60~120:

100.

3. The method for co-processing fly ash from waste incineration and leachate membrane concentrate according to claim 1, characterized in that, The phosphate mentioned in step (1) is any one or a mixture of sodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, and sodium hexametaphosphate.

4. The method for co-treating fly ash from waste incineration and leachate membrane concentrate according to claim 1, characterized in that, The adsorbent powder mentioned in step (2) is any one or a mixture of zeolite powder, expanded perlite powder, expanded vermiculite powder, and sepiolite powder.

5. The method for co-processing fly ash from waste incineration and leachate membrane concentrate according to claim 1, characterized in that, The liquid-solid ratio of the landfill leachate membrane concentrate and the phosphorus coal slime fly ash adsorption mixture in step (3) is 0.5~1.5:100mL / g.

6. The method for co-processing fly ash from waste incineration and leachate concentrate according to claim 1, characterized in that, The aging time mentioned in step (4) is 14 to 28 days.

7. The method for co-processing fly ash from waste incineration and leachate membrane concentrate according to claim 1, characterized in that, The continuous aeration time mentioned in step (5) is 4 to 16 days.

8. The method for co-processing fly ash from waste incineration and leachate membrane concentrate according to claim 1, characterized in that, The calcination time in step (6) is 0.5 to 4.5 hours; the calcination temperature is 800 to 1200℃.

9. The method for co-processing fly ash from waste incineration and leachate membrane concentrate according to claim 1, characterized in that, The liquid-to-solid ratio of water and active detoxification residue in step (7) is 0.4~0.6:1mL / g; the curing time is 7~28 days.

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