阅读说明：本技术 一种基于细菌的固体废弃物焚烧炉渣无害化强化处理方法 (Bacteria-based harmless strengthening treatment method for solid waste incinerator residues ) 是由 唐强 黄钰程 高玉峰 史培新 田盎然 张军辉 廖昕 何稼 王志丰 卞夏 于 2021-10-21 设计创作，主要内容包括：本发明提供了一种基于细菌的固体废弃物焚烧炉渣无害化强化处理方法。本发明处理方法为：将原始炉渣移入细菌与钙源的混合液1中,所述原始炉渣在混合液的液面以下,抽真空并超声处理,之后浸泡,固液分离得到预处理炉渣和混合液2；用尿素溶液喷洒所述预处理炉渣的表面,并将环氧树脂喷涂在所得炉渣的表面得到炉渣1；将所得炉渣1放入石灰与淀粉的混合物中并翻滚,使得炉渣1和混合物充分混合得到炉渣2；将所得炉渣2取出,并在所述炉渣2的表面喷洒所述混合液2得到炉渣3；将炉渣3表面覆盖土工布,养护5-14天,即完成炉渣的无害化处理。本发明处理方法可有效的对炉渣材料表面裂缝进行修复,完成晶体间胶结,并大幅降低其吸水率,从而提升其强度。(The invention provides a bacteria-based harmless strengthening treatment method for solid waste incinerator residues. The processing method comprises the following steps: transferring original slag into a mixed solution 1 of bacteria and a calcium source, vacuumizing and ultrasonically treating the original slag below the liquid level of the mixed solution, then soaking, and performing solid-liquid separation to obtain pretreated slag and a mixed solution 2; spraying urea solution on the surface of the pretreated slag, and spraying epoxy resin on the surface of the obtained slag to obtain slag 1; putting the obtained slag 1 into a mixture of lime and starch, and rolling to ensure that the slag 1 and the mixture are fully mixed to obtain slag 2; taking out the obtained slag 2, and spraying the mixed liquid 2 on the surface of the slag 2 to obtain slag 3; covering the surface of the slag 3 with geotextile, and maintaining for 5-14 days to finish the harmless treatment of the slag. The treatment method can effectively repair the surface cracks of the slag material, complete the cementation between crystals and greatly reduce the water absorption rate of the slag material, thereby improving the strength of the slag material.)

1. A harmless strengthening treatment method of solid waste incinerator slag based on bacteria is characterized by comprising the following steps:

s1: transferring original slag into a mixed solution 1 of bacteria and a calcium source, vacuumizing and ultrasonically treating the original slag below the liquid level of the mixed solution, then soaking for 6-36h, and performing solid-liquid separation to obtain pretreated slag and a mixed solution 2;

s2: spraying the surface of the pretreated slag in S1 with a urea solution, and spraying an epoxy resin on the surface of the slag to obtain slag 1;

s3: putting the slag 1 obtained in the step S2 into a mixture of lime and starch, and rolling to ensure that the slag 1 and the mixture are fully mixed to obtain slag 2;

s4: taking out the slag 2 obtained in the step S3, and spraying the mixed solution 2 and the urea solution in the step S1 on the surface of the slag 2 to obtain slag 3;

s5: and covering the surface of the slag 3 in the S4 with geotextile, and maintaining for 5-14 days to finish the harmless treatment of the slag.

2. The method for harmlessly strengthening the treatment of the solid waste incinerator slag according to claim 1, wherein the vacuum condition in S1 is a vacuum degree of-75 kPa or less.

3. The method for harmlessly strengthening the treatment of the solid waste incinerator slag according to claim 1, wherein said bacteria in S1 are one or more of bacillus pasteurii, bacillus sphaericus, bacillus megaterium, bacillus subtilis, bacillus mucilaginosus, and cyanobacteria.

4. The method as set forth in claim 1, wherein OD of bacteria in S1 is determined by the method₆₀₀Greater than 1.

5. The method for harmlessly strengthening the treatment of the solid waste incinerator slag according to claim 1, wherein said calcium source in S1 is one or more selected from the group consisting of calcium nitrate, calcium acetate and calcium chloride.

6. The method for harmlessly strengthening the treatment of the solid waste incinerator slag according to claim 1, wherein the concentration of the calcium source in the mixed solution of the bacteria and the calcium source in S1 is 0.5 to 1.5 mol/L.

7. The method for the harmless reinforcement treatment of the solid waste incinerator slag according to claim 1, wherein the frequency of said ultrasonic waves in S1 is 30 to 60kHz, and the time of ultrasonic waves is 5 to 40 minutes.

8. The method of claim 1, wherein the ratio of the concentration of the urea solution in S2 to the concentration of the calcium source in S1 is 1: 0.76-1: 1.

9. the method for harmlessly strengthening the treatment of the solid waste incinerator slag according to claim 1, wherein the urea solution is sprayed at least three times in S2.

10. The method for harmlessly strengthening the treatment of the solid waste incinerator slag according to claim 1, wherein the mass of the starch in the mixture of lime and starch in S3 is 3 to 10% of the total mass.

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a bacteria-based harmless strengthening treatment method for solid waste incinerator residues.

Background

With the advance of urbanization and economic development, the yield of municipal solid waste (also called domestic garbage) is increased year by year, and the conventional treatment methods such as landfill treatment and the like become bottlenecks due to the prominent land resources and negative influence on the surrounding environment. The incineration treatment of the household garbage has the advantages of small occupied space, high effect of reducing the volume and the weight of the initial garbage (70 percent of the volume and 70-80 percent of the weight), and recyclable energy, so that policy support and rapid development are realized. After the household garbage is incinerated, 20-30% of slag still remains in the hearth. Because the partial slag contains a plurality of heavy metals, the leaching index of partial environment is possibly out of standard, and in addition, the existence of the aluminum-containing compound can also lead the slag to generate reaction volume expansion when meeting water, thereby further influencing the large-scale application of the slag, such as the application of the slag as road filler or concrete admixture and the like. The treatment method for solid waste in the prior art has the following advantages and disadvantages:

first, direct approach landfill limitations and disadvantages: the cost of the stabilizing agent is high, even if the stabilizing agent is only 1 percent of the mixing amount, the expense is too high in consideration of the output of slag of thousands of tons every year in the country; silicate curing agents such as cement have similar effects, but increase the weight by too much. Finally, the landfill is not a good method considering the limited storage capacity resources of the existing sanitary landfill sites of all cities.

Second, wet/dry processing: this type of treatment involves a considerable amount of secondary pollution, in particular acid waste water and the corresponding sludge, and is recommended to be used with caution.

Finally, the physical and chemical limitations of the slag itself: the slag thus differs in the origin of the initial refuse and different crystals are formed during sintering. The generated partial heavy metal compounds are in a water-soluble form or an acid-soluble form, so that heavy metals in the heavy metal compounds are very easy to release in a natural environment and enter an underground water-soil environment, the health of a human body is influenced through a food chain, meanwhile, strong cementation sometimes lacks among sintered crystals, so that more open cracks exist on the surface of the slag, the water absorption rate of the slag is greatly improved due to the existence of the cracks, the water absorption rate is increased, and the strength of the material is further reduced.

Disclosure of Invention

In order to solve the technical problems, the invention provides a bacteria-based harmless strengthening treatment method for solid waste incinerator residues.

A bacteria-based municipal solid waste incinerator slag harmless strengthening treatment method comprises the following steps:

s1: transferring original slag into a mixed solution 1 of bacteria and a calcium source, vacuumizing and ultrasonically treating the original slag below the liquid level of the mixed solution, then soaking for 6-36h, and performing solid-liquid separation to obtain pretreated slag and a mixed solution 2;

s2: spraying the surface of the pretreated slag in S1 with a urea solution, and spraying an epoxy resin on the surface of the slag to obtain slag 1;

s3: putting the slag 1 obtained in the step S2 into a mixture of lime and starch, and rolling to ensure that the slag 1 and the mixture are fully mixed to obtain slag 2;

s4: taking out the slag 2 obtained in the step S3, and spraying the mixed solution 2 and the urea solution in the step S1 on the surface of the slag 2 to obtain slag 3;

s5: and covering the surface of the slag 3 in the S4 with geotextile, and maintaining for 5-14 days to finish the harmless treatment of the slag.

In one embodiment of the present invention, the vacuum condition in S1 is a vacuum degree of less than or equal to-75 kPa.

In one embodiment of the present invention, the bacteria in S1 are one or more of bacillus pasteurii, bacillus sphaericus, bacillus megaterium, bacillus subtilis, bacillus mucilaginosus and cyanobacteria. The bacteria are urease-producing microorganisms that promote the hydrolysis of urea to carbonate, which combines with calcium ions to form calcium carbonate.

In one embodiment of the present invention, OD of the bacterium described in S1₆₀₀Greater than 1.

In one embodiment of the present invention, the calcium source in S1 is selected from one or more of calcium nitrate, calcium acetate and calcium chloride.

In one embodiment of the present invention, the concentration of the calcium source in the mixed solution of the bacteria and the calcium source in S1 is 0.5 to 1.5 mol/L.

In one embodiment of the present invention, the frequency of the ultrasound in S1 is 30-60kHz, and the time of the ultrasound is 5-40 minutes.

In one embodiment of the invention, the ratio of the concentration of the urea solution in S2 to the concentration of the calcium source in S1 is 1: 0.76-1: 1.

in one embodiment of the invention, the urea solution is sprayed at least three times in S2.

In one embodiment of the invention, the mass of the starch in the mixture of lime and starch in S3 is 3-10% of the total mass.

Compared with the prior art, the technical scheme of the invention has the following advantages:

1, the ultrasonic wave has 4 main functions:

(1) washing off heavy metals on the surface which are easy to be removed; (2) the pore and the crack width are enlarged, so that bacteria, a calcium source and a urea solution can enter more easily; (3) the surface and the interior of the slag after ultrasonic cleaning are higher and lower, so that the specific surface area of the slag is increased, and a larger chemical reaction site is provided; (4) and bacterial cells are broken, so that urease in bacteria is dissolved into the solution, and slag is easy to enter the pores to improve the filling effect of the pores.

2, the epoxy resin has 5 main functions:

(1) the residual urea and the calcium source are blocked in the pores so as to avoid the loss of the residual urea and the calcium source, so that the reaction can be carried out for a long time; (2) the plugging filling effect on the pores and cracks on the surface of the slag can be realized; (3) the epoxy resin has good cohesiveness, so that calcium carbonate generated by bacteria can be firmly fixed on the surface and inside of the slag; (4) the epoxy resin can effectively bond the mixture of lime and starch and is used for paving the following external calcification coating treatment of lime and bacteria; (5) can promote the heavy metal to generate chemical reactions such as ion exchange, chelation effect and the like, and solidify the heavy metal into more stable compounds so that the compounds are not easy to leach out.

Lime has 3 main functions:

(1) the lime can provide a calcium source for the bacteria to generate calcium carbonate; (2) the calcium carbonate can be formed with water and carbon dioxide in the air to solidify harmful substances such as heavy metals in the slag; (3) the incorporation of lime can improve slag strength.

4, starch has mainly 2 functions:

(1) providing nutrients to the bacteria therein; (2) the bonding performance of the epoxy resin and the lime is improved.

The geotextile mainly plays a role in water retention and moisture retention and provides proper reaction conditions for calcium carbonate production.

The bacteria used in the invention are derived from natural environment, so the invention is environment-friendly and harmless, no additional product is produced except for strengthening slag aggregate, and secondary pollution is avoided. The treatment method can effectively repair the surface cracks of the slag material, complete the cementation between crystals and greatly reduce the water absorption rate of the slag material, thereby improving the strength of the slag material. Meanwhile, the crystallization and the wrapping of heavy metal are completed, and the dissolution of harmful heavy metal is effectively avoided. In addition, the cost is low, the method is suitable for batch use, the produced reinforced slag aggregate can be sold, and the economic benefit is huge according to the existing aggregate.

The bacteria used in the invention are derived from natural environment, so the invention is environment-friendly and harmless, no additional product is produced except for strengthening slag aggregate, and secondary pollution is avoided. The method can effectively repair the surface cracks of the slag material, complete the cementation between crystals and greatly reduce the water absorption rate of the slag material, thereby improving the strength of the slag material. Meanwhile, the crystallization and the wrapping of heavy metal are completed, and the dissolution of harmful heavy metal is effectively avoided. In addition, the cost is low, the method is suitable for batch use, the produced reinforced slag aggregate can be sold, and the economic benefit is huge according to the existing aggregate.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1 is an aggregate obtained by crushing waste incineration slag;

FIG. 2 is a SEM image of a surface of a slag particle;

FIG. 3 is a calcium carbonate cement formation process according to the present invention;

FIG. 4 is a process flow diagram of the present invention;

FIG. 5 shows the heavy metal leaching changes before and after the treatment according to the invention.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Example 1

In this example, anhydrous calcium chloride was prepared, and the calcium ion concentration was 0.5 mol/L. Preparing a Bacillus pasteurii bacterial solution, and measuring OD by using a spectrophotometer₆₀₀OD thereof₆₀₀Is 1.3. Transferring the slag into the mixed liquid of the bacteria and the calcium source, immersing the slag below the liquid level, vacuumizing to enable the relative vacuum degree to be-75 kPa, treating for 5 minutes by using ultrasonic waves with the frequency of 30kHz, and then continuously soaking for 6 hours; preparing a urea solution, wherein the ratio of the concentration of the urea solution to the calcium source is controlled to be 1: 0.8. taking out the slag, spraying urea solution on the surface of the slag for 3 times, and spraying epoxy resin on the surface of the slag after the last spraying is finished. Preparing lime and starch, wherein the mass of the starch accounts for about 3% of the total mass, mixing the lime and the starch, uniformly stirring, and quickly putting the slag into a lime and starch mixture and slightly rolling to enable the surface of the slag to be fully stained with the mixture. Taking out the slagAnd spraying bacteria on the surface of the mixed solution of urea and calcium source twice. Covering a layer of geotextile on the surface of the slag, and curing for 5 days. And taking out the slag particles, and completing the harmless treatment and strengthening process of the slag particles to obtain a final sample.

Example 2

In this example, anhydrous calcium chloride was prepared, and the calcium ion concentration was 1 mol/L. Preparing a Bacillus pasteurii bacterial solution, and measuring OD by using a spectrophotometer₆₀₀OD thereof₆₀₀Is 1.3. Transferring the slag into the mixed liquid of the bacteria and the calcium source, immersing the slag below the liquid level, vacuumizing to enable the relative vacuum degree to be-75 kPa, treating for 20 minutes by using ultrasonic waves with the ultrasonic frequency of 45kHz, and then continuously soaking for 12 hours; preparing a urea solution, wherein the ratio of the concentration of the urea solution to the calcium source is controlled to be 1: 0.9. taking out the slag, spraying urea solution on the surface of the slag for 3 times, and spraying epoxy resin on the surface of the slag after the last spraying is finished. Preparing lime and starch, wherein the mass of the starch accounts for about 5% of the total mass, mixing the lime and the starch, uniformly stirring, and quickly putting the slag into a lime and starch mixture and slightly rolling to enable the surface of the slag to be fully stained with the mixture. Taking out the slag, spraying bacteria on the surface of the slag, and continuously spraying the mixed solution of urea and calcium source twice. Covering a layer of geotextile on the surface of the slag, and curing for 10 days. And taking out the slag particles, and completing the harmless treatment and strengthening process of the slag particles to obtain a final sample.

Example 3

In this example, anhydrous calcium chloride was prepared, and the calcium ion concentration was 1.5 mol/L. Preparing a bacillus pasteurii bacterial solution, and measuring O by using a spectrophotometer_D600OD thereof₆₀₀Is 1.3. Transferring the slag into the mixed liquid of the bacteria and the calcium source, immersing the slag below the liquid level, vacuumizing to enable the relative vacuum degree to be-75 kPa, treating the slag for 40 minutes by using ultrasonic waves with the ultrasonic frequency of 60kHz, and then continuously soaking the slag for 36 hours; preparing a urea solution, wherein the ratio of the concentration of the urea solution to the calcium source is controlled to be 1: 1. taking out the slag, spraying urea solution on the surface of the slag for 3 times, and spraying epoxy resin on the surface of the slag after the last spraying is finished. Preparing lime and starch, wherein the mass of the starch accounts for about 10% of the total mass, mixing the lime and the starch, stirring uniformly, and quickly mixingThe slag is put into the mixture of lime and starch and rolls slightly to make the surface of the slag fully adhered with the mixture. Taking out the slag, spraying bacteria on the surface of the slag, and continuously spraying the mixed solution of urea and calcium source twice. Covering a layer of geotextile on the surface of the slag, and curing for 14 days. And taking out the slag particles, and completing the harmless treatment and strengthening process of the slag particles to obtain a final sample.

Example 4

In this example, anhydrous calcium chloride was prepared, and the calcium ion concentration was 1 mol/L. Preparing Bacillus sphaericus solution, and measuring OD with spectrophotometer₆₀₀OD thereof₆₀₀Is 1.3. Transferring the slag into the mixed liquid of the bacteria and the calcium source, immersing the slag below the liquid level, vacuumizing to enable the relative vacuum degree to be-75 kPa, treating for 20 minutes by using ultrasonic waves with the ultrasonic frequency of 45kHz, and then continuously soaking for 12 hours; preparing a urea solution, wherein the ratio of the concentration of the urea solution to the calcium source is controlled to be 1: 0.9. taking out the slag, spraying urea solution on the surface of the slag for 3 times, and spraying epoxy resin on the surface of the slag after the last spraying is finished. Preparing lime and starch, wherein the mass of the starch accounts for about 5% of the total mass, mixing the lime and the starch, uniformly stirring, and quickly putting the slag into a lime and starch mixture and slightly rolling to enable the surface of the slag to be fully stained with the mixture. Taking out the slag, spraying bacteria on the surface of the slag, and continuously spraying the mixed solution of urea and calcium source twice. Covering a layer of geotextile on the surface of the slag, and curing for 10 days. And taking out the slag particles, and completing the harmless treatment and strengthening process of the slag particles to obtain a final sample.

Test example

Samples obtained in example 1, example 2, example 3 and example 4 and untreated solid slag were subjected to water absorption verification, metal leaching and CBR change tests according to highway engineering aggregate test regulation (JTG E42-2005), and heavy metal leaching was measured by TCLP. The results are shown in tables 1-2 and FIG. 5.

Fig. 5 shows the leaching characteristics of heavy metals in the finished product under different operating methods. As can be seen from the figure, after the slag is treated by the method of the embodiment 1, the heavy metal leaching of the slag can be reduced by about 21.5 percent on average; after the treatment of the embodiment 2, the heavy metal leaching can be reduced by about 29.5 percent on average; after the treatment of the embodiment 3, the heavy metal leaching can be reduced by about 42.4 percent on average; after the treatment of the example 4, the heavy metal leaching can be reduced by about 33.5 percent on average.

Table 1 shows the water absorption of the final product according to the different methods of operation. As can be seen from the table, after the slag is treated by the case 1, the water absorption of the slag is reduced by about 11.5 percent; after the treatment of case 2, the water absorption rate can be reduced by about 28.2 percent; after the treatment of case 3, the water absorption rate can be reduced by about 34.0 percent; after the treatment of case 4, the water absorption can be reduced by about 15.4%.

Table 2 shows the CBR values of the finished products under different operating methods. As can be seen from the table, the CBR value of the slag treated in case 1 is improved by about 16.3%; after case 2 treatment, the CBR value is improved by about 18.7%; after case 3 treatment, the CBR value is improved by about 24.3%; the CBR value improved by about 14.4% after case 4 treatment.

After the treatment of the invention, the open pores of the slag are closed because calcium carbonate precipitation is generated under the action of bacteria, and the water absorption of the slag is obviously reduced. The closure of the open pores increases the strength of the single particles of slag, while the calcium carbonate also covers the slag surface, which results in a significant increase in its CBR value. In addition, calcium carbonate covers the surface and the internal pores of the slag, so that heavy metals in the slag are wrapped by a calcium carbonate shell and are not easy to leach out. In addition, the heavy metal elements in the slag are easy to generate chemical reactions such as ion exchange, chelation reaction and the like to convert the heavy metal elements into more stable compounds, so that the harmless treatment effect is further improved. The treatment effect can be improved by properly increasing the concentration of the calcium source and the urea, increasing the ultrasonic frequency, and increasing the treatment time and the maintenance time. Compared with Bacillus sphaericus, the Bacillus pasteurianus has better effect.

TABLE 1 Water absorption Change before and after treatment

TABLE 2 CBR value Change before and after treatment

Processing method	CBR value
		Untreated	81.5％
Example 1	94.8％
		Example 2	96.7％
Example 3	101.3％
		Example 4	93.2％

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.