Fly ash glass body and application thereof in sewage treatment

Abstract

The invention belongs to the technical field of sewage treatment fillers, and particularly relates to a fly ash glass body and application thereof in sewage treatment. The invention provides a novel utilization mode of household garbage fly ash, namely, fly ash generated in the household garbage incineration process of a garbage treatment plant is transformed to obtain a fly ash glass body, and the fly ash glass body is used as a constructed wetland filler for sewage treatment and is matched with an activated carbon component obtained after biological matrix transformation to treat sewage. Experimental results show that the filler provided by the invention can effectively remove various pollutant components in sewage, not only realizes reutilization of waste resources such as household garbage fly ash, biomass and the like, improves the utilization rate of the waste resources, but also improves the purification effect of the constructed wetland.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment fillers, and specifically relates to fly ash vitreous body and its application, especially in sewage treatment. Background Art

[0002] In recent years, with the acceleration of the urbanization level in China, the generation amount of urban domestic waste has also increased significantly. At present, the harmless treatment of domestic waste mainly adopts a circulating fluidized bed incinerator for incineration. However, due to the low calorific value of the waste, it is difficult to burn alone, so fossil fuels such as coal and fuel oil are required as combustion improvers to achieve stable combustion. Coupled with the technological characteristics of the circulating fluidized bed incinerator, a large amount of fly ash is generated during the waste incineration process.

[0003] At present, domestic waste fly ash is recognized as hazardous solid waste and is mainly landfilled. In the long run, it will cause serious environmental pollution. Therefore, how to safely and effectively dispose of waste incineration fly ash and improve its resource utilization rate has become an urgent environmental and social problem.

[0004] An artificial wetland is an integrated ecosystem constructed and operated artificially. Similar to a marshland, it is a new type of sewage treatment technology. By controlling the dosing of sewage, sludge and other pollutants onto an artificially constructed wetland, during the process of the sewage and sludge flowing in a certain direction, the physical, chemical and biological triple synergistic effects of soil, artificial media, plants and microorganisms are utilized to achieve the treatment of sewage and sludge. It has the advantages of ecology, high efficiency, low operating cost, simple management and good effluent quality. As the most important part of the artificial wetland, the artificial wetland filler plays a major role in the artificial wetland sewage treatment technology. The selection of its type, combination method and height are all important links in the engineering design of the artificial wetland.

[0005] Traditional fillers used in artificial wetlands, such as gravel, zeolite, etc., although they have a certain adsorption capacity for sewage, have problems of high cost and single function, and their adsorption effect is limited, and it is extremely difficult to degrade heavy metals. Although organic flocculants have good decontamination and water purification effects, the cost of organic flocculants is too high.

[0006] Transforming fly ash and applying it to artificial wetland fillers for sewage treatment can not only achieve the reduction, resource utilization and harmless treatment of waste fly ash, but also greatly improve the sewage treatment effect. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a fly ash vitreous body and its application, especially in sewage treatment.

[0008] The inventor's unit, through cooperation and research with a waste fly ash disposal unit, collects the fly ash generated after domestic waste incineration, and uses a specific high-temperature melting treatment to obtain a black vitreous body. After passing the toxicity test, it is used as a filler for the constructed wetland in sewage treatment.

[0009] In the technical solution provided by the present invention, after the domestic waste incineration fly ash is subjected to high-temperature melting treatment, its interior presents a loose and porous structure with dense pores and a significantly increased specific surface area. Coupled with the unique stable skeleton structure of inorganic elements, it shows a good adsorption effect in sewage treatment, greatly improving the resource utilization rate of domestic waste incineration fly ash.

[0010] Furthermore, the first aspect of the present invention is to provide an application of fly ash vitreous body, specifically applying the fly ash vitreous body to sewage treatment as a filler material for sewage treatment. The fly ash vitreous body is obtained by high-temperature melting of domestic waste incineration fly ash.

[0011] The second aspect of the present invention is to provide a constructed wetland filler containing fly ash vitreous body. The constructed wetland filler is used in sewage treatment and includes the following components: fly ash vitreous body, modified activated carbon, and porous ceramsite. The weight ratio of each component is: fly ash vitreous body: modified activated carbon: porous ceramsite = 5 - 10: 1 - 5: 1.

[0012] Preferably, the constructed wetland filler is arranged in layers. When using the constructed wetland filler to treat sewage, the sewage passes through the modified activated carbon layer, porous ceramsite layer, and fly ash vitreous body layer from top to bottom in sequence and then completes purification.

[0013] The third aspect of the present invention is to provide a preparation method of the above fly ash vitreous body, including the following steps: S1 Collection of domestic waste incineration fly ash: Collect the flue gas and incineration residues after domestic waste incineration from the waste incineration treatment plant. After purification and dust removal, domestic waste incineration fly ash is obtained; S2 Mixing and forming: Under the protection of inert gas, melt the silicon-containing raw material and the domestic waste incineration fly ash collected in S1 at a high temperature above 1700 °C, then rapidly cool and crush them into solid particles with a particle size of 3 - 20 mm to obtain fly ash vitreous body particles.

[0014] In the above preparation method of fly ash vitreous body, preferably, in S2, the silicon-containing raw material includes but is not limited to any one of waste silicon wafers, broken glass, quartz sand, and kaolin.

[0015] More preferably, in S2, the mass ratio of the silicon-containing raw material to the domestic waste incineration fly ash is 1: 10 - 20, and the high-temperature melting temperature is 1700 - 2500 °C.

[0016] The fly ash obtained by incinerating domestic waste using the method of the present invention is subjected to high-temperature melting. Under relatively high temperature conditions and with the protection of inert gas, various organic substances contained in the fly ash, including highly toxic components such as dioxins, are pyrolyzed at high temperature. Research shows that the decomposition temperature of dioxins is 705 °C and they can be completely decomposed at 800 °C, thus not causing secondary pollution to the environment. In addition, the inorganic components in the fly ash are retained due to their high stability. These inorganic elements such as silicon, aluminum, and manganese have unique framework structures, endowing the fly ash vitreous body with excellent adsorption properties.

[0017] Moreover, in the process of treating fly ash, the present invention adds some silicon-containing raw materials, and these components and the original inorganic components in the fly ash are melted and solidified to form a vitreous material with a loose structure and porous interior.

[0018] Furthermore, in the above artificial wetland filler provided by the present invention, the preparation method of the modified activated carbon is as follows: It is obtained by using biomass as the raw material, screening, cleaning, drying, pulverizing and sieving, and then performing high-temperature carbonization to obtain carbonized powder, and finally performing modified activation.

[0019] Preferably, the biomass is selected from at least one of corn straw, cotton stalk, wheat straw, soybean straw, reed stalk, shell, and shrimp shell.

[0020] Preferably, the procedure of the high-temperature carbonization is: first heat-treat the pulverized and sieved biomass powder at 350 - 500 °C for 10 - 20 min, and then calcine it at 700 - 900 °C for 30 - 60 min to obtain carbonized powder.

[0021] Preferably, for the modified activation, first soak the carbonized powder with a sodium hydroxide solution with a mass fraction of 20% - 50% for 12 - 24 h, then filter and wash the powder with water until the pH of the washing solution is 7.0, and then soak the carbonized powder in the mixed acid solution for 30 - 50 min.

[0022] Among them, the mass-volume ratio of the carbonized powder to the sodium hydroxide solution is 1 g: 2 - 3 mL. In the mixed acid solution, the volume ratio of acetic acid: oxalic acid: hydrochloric acid is 1: 1 - 3: 1 - 5, and the mass-volume ratio of the carbonized powder to the mixed acid solution is 1 g: 2 - 6 mL.

[0023] The beneficial effects of the present invention are as follows: The present invention transforms waste components such as fly ash, incineration residues, etc. generated during the incineration of domestic waste in a waste incineration plant, as well as various agricultural wastes such as straw and shells, and obtains fly ash glass, modified activated carbon and other materials with good adsorption properties. By controlling the preparation process parameters of these adsorption materials, their pore size, porosity and the functional group structure they carry are adjusted, and the above-mentioned materials are combined in a specific combination form, ultimately achieving a good decontamination effect.

[0024] The method of the present invention not only achieves the reduction, resource utilization and harmless disposal of waste resources such as fly ash from the incineration of domestic waste and biomass, thereby improving resource utilization, but also reduces the construction and maintenance costs of artificial wetlands. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of an artificial wetland filler device provided in Example 2 of the present invention; Figure 2 A schematic diagram of the structure of an artificial wetland filler device provided in Example 8 of the present invention; Among them, 1-modified activated carbon layer, 2-porous ceramsite layer, 3-fly ash glass layer, 4-water inlet, 5-water outlet. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in conjunction with specific implementation methods.

[0027] Example 1 1.1 Prepare fly ash glass as follows: S1 Collection of fly ash from incineration of domestic waste: Collect flue gas and incineration residues from the waste incineration treatment plant, and obtain fly ash from incineration of domestic waste after purification and dust removal; S2 mixing and molding: the silicon-containing raw material and the domestic waste incineration fly ash collected in S1 are mixed, and then melted at a temperature of 1800°C under the protection of inert gas, and rapidly cooled to obtain block-shaped black solids, which are crushed into solid particles with a particle size of about 5 mm, namely, fly ash glass, wherein the silicon-containing raw material is a mixture of broken glass slag and broken ceramic slag, and the mass ratio of the silicon-containing raw material to the domestic waste incineration fly ash is 1:10.

[0028] The test results of the components in the fly ash glass obtained by the above method are shown in Table 1 below.

[0029] Table 1 Full element analysis results of fly ash vitreous Component Content (%) Component Content (%) <![CDATA[Sodium 2 O]]> 8.55 <![CDATA[Fe 2 O 3 > 1.23 MgO 3.95 NiO 0.0045 <![CDATA[Al 2 O 3 > 1.52 CuO 0.0136 <![CDATA[SiO 2 > 54.0 ZnO 0.202 <![CDATA[P 2 O 5 > 0.166 SrO 0.0518 <![CDATA[SO 3 > 0.109 <![CDATA[ZrO 2 > 0.0192 Cl 0.656 <![CDATA[MoO 3 > 0.427 <![CDATA[K 2 O]]> 1.11 <![CDATA[SnO 2 > 0.0219 CaO 26.7 BaO 0.0671 <![CDATA[TiO 2 > 0.149 <![CDATA[WO 3 > 1.03 <![CDATA[Cr 2 O 3 > 0.0318 PbO 0.0108 MnO 0.0401

[0030] From the full-element analysis data in Table 1, it can be seen that the fly ash vitreous obtained by the method of the present invention contains rich inorganic mineral elements. Most of the various inorganic elements exist in the form of oxidation states, with extremely high stability and good lattice structure, endowing the fly ash vitreous with a larger specific surface area and good adsorption properties.

[0031] 1.2 Preparation of modified activated carbon, the method is as follows: Using reed stalks and shells as raw materials, the weight ratio of reed stalks to shells is 1:3; After screening and cleaning the reed stalks and shells, they are dried using a dryer, and then crushed into powder and passed through a 200-mesh sieve for standby; The mixed powder of reed and shell after crushing and sieving is first heat-treated at 400 °C for 20 min, and then calcined at 850 °C for 30 min to obtain carbonized powder.

[0032] Then, the above carbonized powder is subjected to modified activation treatment. The specific operation is as follows: The carbonized powder is soaked in a sodium hydroxide solution with a mass fraction of 30% for 12 h, then filtered and washed with clear water until the pH of the washing liquid is 7.0, and then the carbonized powder is soaked in the mixed acid solution for 40 min; Among them, the mass-volume ratio of the carbonized powder to the sodium hydroxide solution is 1 g: 3 mL. In the mixed acid solution, the volume ratio of acetic acid: oxalic acid: hydrochloric acid is 1:2:2, and the mass-volume ratio of the carbonized powder to the mixed acid solution is 1 g: 5 mL to obtain modified activated carbon.

[0033] The modified activated carbon prepared by the method of this example has good porosity and appropriate pore size. At the same time, the modified activated carbon carries a characteristic functional group structure and has a good removal effect on specific pollutant components in sewage.

[0034] Examples 2 to 6 Using the fly ash vitreous and modified activated carbon prepared in Example 1 as raw materials, an artificial wetland filler for sewage treatment is prepared. In the artificial wetland filler, the specific ratio of each component is shown in Table 2.

[0035] Table 2 Dosage ratio of components of artificial wetland filler in each example (parts by weight) Raw material Example 2 Example 3 Example 4 Example 5 Example 6 Fly ash vitreous body 70 70 80 60 50 Modified activated carbon 20 25 20 20 40 Porous ceramsite 10 10 10 10 10

[0036] In Examples 2-6, in accordance with the attached Figure 1 As shown in the order, the three artificial wetland filler components are laid layer by layer. That is, after the sewage passes through the water inlet 4, it first flows through the modified activated carbon layer 1, and then successively flows through the porous ceramsite layer 2 and the fly ash vitreous layer 3, and finally flows out through the water outlet 5.

[0037] At the confluence of a tributary and the main stream in the lower reaches of a river on one side of a chemical industrial park in a certain county of Zibo City, Shandong Province, sewage water samples were taken for testing. The sampling time was July 12, 2024. After testing, the COD in the sewage was 32.5 mg / L, ammonia nitrogen was 3.58 mg / L, TN was 7.72 mg / L, and total phosphorus was 1.32 mg / L.

[0038] The sewage was treated respectively using the artificial wetland fillers provided in the above-mentioned respective embodiments. The adsorption effects of the artificial wetland fillers are shown in Table 3 below.

[0039] Table 3 Purification effects of artificial wetland fillers with different raw material ratios COD Ammonia nitrogen TN TP Example 2 17.4 0.90 1.22 0.25 Example 3 17.2 0.90 1.20 0.24 Example 4 17.1 0.88 1.18 0.24 Example 5 18.3 1.12 1.35 0.38 Example 6 18.9 1.32 1.52 0.55

[0040] Note: The unit of the content of COD, ammonia nitrogen, TN, and TP is: mg / L.

[0041] The results in Table 3 show that after treatment using the artificial wetland fillers in the respective embodiments of the present invention, the contents of various pollutant components in the sewage have been significantly reduced.

[0042] In addition to the above-mentioned respective embodiments, the inventor also conducted the following experiments: Example 7 Different from Example 2, after the components in the artificial wetland filler were mixed evenly, it was used to treat sewage.

[0043] After testing, the contents of various components in the treated sewage were: COD 19.2 mg / L, ammonia nitrogen 1.35 mg / L, TN 1.58 mg / L, and total phosphorus 0.64 mg / L.

[0044] Example 8 Different from Example 2, it was laid in the order of the artificial wetland filler device structure shown in the appendix Figure 2 to treat sewage.

[0045] Appendix Figure 2 In the appendix, when the sewage passes through the water inlet 4, it first flows through the fly ash vitreous layer 3, and then successively flows through the porous ceramsite layer 2 and the modified activated carbon layer 1, and finally flows out through the water outlet 5.

[0046] After testing, the contents of various components in the treated sewage were: COD 19.6 mg / L, ammonia nitrogen 1.55 mg / L, TN 1.61 mg / L, and total phosphorus 0.73 mg / L.

[0047] Example 9 Different from Example 2, when preparing the modified activated carbon, in the mixed acid solution used, the volume ratio of acetic acid: oxalic acid: hydrochloric acid was 1:2:4.

[0048] After uniformly mixing the obtained artificial wetland fillers, the sewage is treated. After detection, the content of each component in the treated sewage is as follows: COD is 17.2 mg / L, ammonia nitrogen is 0.89 mg / L, TN is 1.19 mg / L, and total phosphorus is 0.23 mg / L.

[0049] The results show that although the addition amount of hydrochloric acid increased during the preparation of activated carbon, and the treatment effect of the obtained artificial wetland fillers on sewage was also improved compared with that in Example 2, the improvement effect was not significant, and the increase in the hydrochloric acid content greatly increased the treatment cost of the artificial wetland fillers.

[0050] Comparative Examples 1-3 In Comparative Examples 1-3, the ratios of the raw materials in the artificial wetland fillers were adjusted respectively. The ratio of each raw material of the artificial wetland fillers is shown in Table 4 below.

[0051] Table 4 Raw material ratios (parts by weight) of the fillers in Comparative Examples 1-3 Raw material Comparative example 1 Comparative example 2 Comparative example 3 Fly ash vitreous body 20 40 40 Modified activated carbon 40 20 40 Porous ceramsite 40 40 20

[0052] Comparative Example 4 In this comparative example, the difference in the preparation method of the modified activated carbon from that in Example 1 is as follows: During the modified activation treatment, the operation is as follows: only soak the carbonized powder with a sodium hydroxide solution with a mass fraction of 30% for 12 h, where the mass-volume ratio of the carbonized powder to the sodium hydroxide solution is 1 g: 3 mL, to obtain the modified activated carbon.

[0053] Comparative Example 5 In this comparative example, the difference in the preparation method of the modified activated carbon from that in Example 1 is as follows: During the modified activation treatment, the operation is as follows: only soak the carbonized powder with a mixed acid solution for 40 min; in the mixed acid solution, the volume ratio of acetic acid: oxalic acid: hydrochloric acid is 1:2:2, and the mass-volume ratio of the carbonized powder to the mixed acid solution is 1 g: 5 mL, to obtain the modified activated carbon.

[0054] Comparative Example 6 In this comparative example, the difference in the preparation method of the modified activated carbon from that in Example 1 is as follows: During the modified activation treatment, in the mixed acid, the volume ratio of acetic acid: oxalic acid = 1:2, and the rest are the same as in Example 1.

[0055] Comparative Example 7 In this comparative example, the difference in the preparation method of the modified activated carbon from that in Example 1 is as follows: During the modified activation treatment, hydrochloric acid is used instead of the mixed acid solution, and the rest are the same as in Example 1.

[0056] In Comparative Examples 4-7, the artificial wetland fillers were prepared according to the proportioning and filler laying sequence in Example 2, and the above sewage was treated. The purification effects are shown in Table 5 below.

[0057] Table 5 Purification effects of various artificial wetland fillers in the comparative examples COD Ammonia nitrogen TN TP Comparative example 1 22.6 2.20 4.27 0.82 Comparative example 2 19.9 3.50 5.56 0.92 Comparative example 3 21.0 2.03 3.96 0.78 Comparative example 4 24.1 2.35 4.68 0.88 Comparative example 5 22.2 2.26 4.22 0.75 Comparative example 6 19.0 2.13 3.81 0.70 Comparative example 7 21.4 2.00 3.90 0.77 Comparative example 8 17.1 1.92 4.25 0.42

[0058] The results in Table 5 show that the artificial wetland fillers obtained by using each comparative example have a certain purification effect on sewage. However, the adsorption degree is limited, and the contents of various pollutants in the sewage do not decrease significantly after adsorption by the artificial wetland filler.

[0059] In the present invention, after the fly ash is transformed and applied to the artificial wetland filler for sewage treatment, not only the reduction, resource utilization and harmless treatment of waste fly ash are realized, but also the artificial wetland filler prepared by compounding the obtained fly ash vitreous body with biomass resources shows excellent purification effects in sewage treatment.

Claims

1. The application of fly ash vitreous in sewage treatment is characterized by: The fly ash glass is used as a filler material for sewage treatment, wherein the fly ash glass is obtained by high-temperature melting of fly ash from the incineration of domestic waste.

2. An artificial wetland filler containing fly ash glass, characterized in that: The artificial wetland filler is used in sewage treatment. The artificial wetland filler includes the following components: fly ash glass, modified activated carbon, and porous ceramsite. The weight ratio of each component is: fly ash glass: modified activated carbon: porous ceramsite = 5~10:1~5:

1.

3. The artificial wetland filler containing fly ash glass as claimed in claim 2, characterized in that: The artificial wetland filler is arranged in layers. When sewage is treated with the artificial wetland filler, the sewage is purified after passing through the modified activated carbon layer, the porous ceramsite layer and the fly ash vitreous layer in sequence from top to bottom.

4. An artificial wetland filler containing fly ash glass as claimed in any one of claims 2 or 3, characterized in that: The fly ash glass body is prepared by the following method: S1 Collection of fly ash from incineration of domestic waste: Collect flue gas and incineration residues from the waste incineration treatment plant, and obtain fly ash from incineration of domestic waste after purification and dust removal; S2 mixing and molding: the silicon-containing raw materials and the domestic waste incineration fly ash collected in S1 are mixed, and then melted at a high temperature above 1700°C under the protection of inert gas, rapidly cooled, and crushed into solid particles with a particle size of 3~20 mm to obtain fly ash glass.

5. The artificial wetland filler containing fly ash glass as claimed in claim 4, characterized in that: The silicon-containing raw materials described in S2 include but are not limited to any one of waste silicon wafers, broken glass, quartz sand, and kaolin.

6. The artificial wetland filler containing fly ash glass as claimed in claim 4, characterized in that: In S2, the mass ratio of the silicon-containing raw material to the fly ash from the incineration of domestic waste is 1:10-20, and the high-temperature melting temperature is 1700-2500°C.

7. An artificial wetland filler containing fly ash glass as claimed in any one of claims 2 or 3, characterized in that: The modified activated carbon is obtained by using biomass as raw material, screening, washing, drying, crushing and screening, and then high-temperature carbonization to obtain carbonized powder, which is finally modified and activated.

8. The artificial wetland filler containing fly ash glass as claimed in claim 7, characterized in that: The biomass is selected from at least one of corn stalks, cotton stalks, wheat stalks, soybean stalks, reed stalks, shells, and dried shrimps.

9. The artificial wetland filler containing fly ash glass as claimed in claim 7, characterized in that: The high temperature carbonization procedure is as follows: the crushed and sieved biomass powder is first heated at 350-500°C for 10-20 min, and then roasted at 700-900°C for 30-60 min to obtain carbonized powder.

10. The artificial wetland filler containing fly ash glass as claimed in claim 7, characterized in that: The modification and activation is to first soak the carbonized powder in a sodium hydroxide solution with a mass fraction of 20%-50% for 12-24 hours, then filter and wash the powder with water until the pH of the washing solution is 7.0, and then soak the carbonized powder in a mixed acid solution for 30-50 minutes; Among them, the mass volume ratio of carbonized powder to sodium hydroxide solution is 1 g: 2~3 mL, in the mixed acid solution, the volume ratio of acetic acid: oxalic acid: hydrochloric acid is 1: 1~3: 1~5, and the mass volume ratio of carbonized powder to mixed acid solution is 1 g: 2~6 mL.

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