A method for synergistically treating waste incineration fly ash, municipal sludge, aged garbage and leachate

Abstract

The application discloses a kind of synergic garbage incineration fly ash, municipal sludge, stale garbage and percolate processing method, comprising the following steps: S1, the undersize of stale garbage is dried, broken;S2, garbage incineration fly ash is mixed with undersize, after strong stirring, mixture b is obtained;S3, municipal sludge is added to the concentrated solution of percolate, and is strongly stirred and heated and is killed, and mixed slurry a is obtained;S4, mixed slurry a is mixed with mixture b and is mixed and stirred evenly;S5, chelating agent and water-soluble polyester fiber are added in mixed material, after mixing evenly, strong stirring is carried out, and solidified body is obtained;S6, solidified body is extruded and formed by using press, after dewatering, curing is carried out, and after inspection qualified, transfer fills and is handled.This application has the advantages of simple operation, heavy metal locking effect is better, no secondary pollution and environmental benefits etc., reaches the purpose of multiple garbage waste collaborative management, waste treatment with waste.

Description

Technical Field

[0001] This invention belongs to the field of integrated co-processing technology of waste, specifically relating to a method for co-processing fly ash from waste incineration, municipal sludge, aged waste, and leachate. Background Technology

[0002] In recent years, there have been some engineering examples of landfill excavation and comprehensive resource utilization of aged waste. Due to the huge quantity of aged waste, its potential and value for resource utilization are enormous. However, the screening materials from aged waste also account for a certain share and need to be further processed.

[0003] Municipal sludge is a solid sediment produced during water treatment at urban wastewater treatment plants or waterworks. Sludge has two sides: on the one hand, it contains a large amount of organic matter and nutrients such as nitrogen, phosphorus, and potassium, but the path to its resource utilization has not yet been opened; on the other hand, some pollutants in the sewage are transferred to the sludge, resulting in high water content, a strong odor, and a large number of pathogens, parasite eggs, heavy metals such as chromium and mercury, and toxic, harmful, and carcinogenic substances that are difficult to degrade, such as dioxins. If it is not effectively treated and disposed of, it can easily cause secondary pollution to groundwater and soil, directly threatening environmental safety and public health.

[0004] Landfill concentrate is wastewater containing high concentrations of organic matter, high salt, and high ammonia nitrogen, formed after membrane treatment of landfill leachate. Currently, it is mainly treated by reinjection into the landfill, re-spraying into the incinerator, or evaporation. Reinjection increases the burden on the subsequent leachate membrane treatment system; re-spraying lowers the furnace temperature, severely affecting the stability of the incineration system and presenting difficult-to-handle problems; evaporation causes scaling in the evaporator, affecting its evaporation efficiency, and consumes a large amount of electrical or thermal energy. In other words, leachate concentrate treatment is characterized by high treatment costs and poor treatment effects.

[0005] Existing technologies mention fly ash co-treatment with sludge, fly ash co-treatment with leachate, and sludge co-treatment with leachate, but there are few cases of comprehensive co-treatment of multiple wastes. Existing technologies have the following drawbacks:

[0006] (1) The chelation and solidification treatment of fly ash generally uses chelating agents. The original fly ash is usually between pH 12 and 13. As the pH value increases, the heavy metals in the fly ash gradually produce their corresponding hydroxide precipitates, and each heavy metal has its own corresponding precipitation pH value. Since Pb and Zn are amphoteric heavy metals, their corresponding hydroxide precipitates redissolve under strongly alkaline conditions, and the solution becomes clear, which requires the addition of more reagents to maintain the locking effect of heavy metals Pb and Zn. According to the method of this invention, the pollutants can be treated in a synergistic manner to achieve the standard treatment, while reducing the amount of reagents used and saving production costs;

[0007] (2) The standard requirement for fly ash solidified body is generally to control the moisture content within 30%. When the amount of water added is small, the solidified body is powdery and not formed, which affects the safety and stability of the stockpile. If more water is added, the curing time of the solidified body will be extended, and more temporary storage rooms need to be built to store the material.

[0008] (3) After the sludge is solidified, it is disposed of in a landfill. When it comes into contact with water, it becomes plastic and in severe cases, it becomes fluid, which affects the safety of the landfill.

[0009] (4) Because the dried waste contains rich nutrients such as humic acid, the technology for preparing organic fertilizer and nutrient-rich soil is relatively mature.

[0010] (5) The concentrated liquid is mainly treated by landfill, incineration or evaporation. Reinjection will increase the burden on the subsequent leachate membrane treatment system. Moreover, relevant standards stipulate that the concentrated liquid generated from leachate treatment should be disposed of separately and should not be reinjected into municipal solid waste landfills or enter centralized sewage treatment facilities. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for treating fly ash from waste incineration, municipal sludge, aged waste and leachate that is simple to operate, low in energy consumption and low in cost, and achieves synergistic treatment of multiple types of waste.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0013] A method for co-treating fly ash from waste incineration, municipal sludge, aged waste, and leachate includes the following steps:

[0014] Step S1: Dry the sieve material of the aged waste, then crush it to obtain sieve material powder for later use;

[0015] Step S2: Mix the fly ash from waste incineration with the sieved powder in a certain proportion, and stir vigorously to obtain mixture b, which is then set aside.

[0016] Step S3: Add municipal sludge with a water content of 80% ± 2% to the leachate concentrate and condition and stir vigorously to obtain sludge slurry with a water content of 90% to 95%. Then heat it to kill harmful and gas-producing microorganisms in the sludge to obtain mixed slurry a.

[0017] Step S4: Mix the mixed slurry a and the mixture b according to the mass ratio and stir evenly, and control the pH value of the mixture to be between 7.0 and 10.0;

[0018] Step S5: Add chelating agent and water-soluble polyester fiber to the mixture, mix evenly and then stir vigorously to obtain a cured body;

[0019] Step S6: The solidified body is extruded and molded using a press. If any filtrate is generated, it is recycled. After dehydration, it is cured. After the solidified body passes inspection, it is transported and disposed of in a landfill.

[0020] As a further improvement of the present invention, in step S1, the undersize of the aged waste contains calcium chloride, silicon dioxide and humus; the undersize of the aged waste is dried at 105℃±5℃ for 1h to 2h, and then crushed to a particle size of 40 mesh to 60 mesh.

[0021] As a further improvement of the present invention, in step S2, the fly ash from waste incineration and the undersize powder are mixed evenly at a mass ratio of 2 to 3:1, and stirred for 15 to 20 seconds in a closed space using a high-powered mixer to obtain mixture b.

[0022] As a further improvement of the present invention, in step S3, the vigorous stirring time is 5 min to 10 min.

[0023] As a further improvement of the present invention, in step S3, the sludge slurry is heated under a constant temperature of 100℃±5℃ for 20min~30min.

[0024] As a further improvement of the present invention, in step S4, the mixed slurry a and the mixture b are mixed and stirred evenly at a mass ratio of 1:1 to 1.5.

[0025] As a further improvement of the present invention, in step S5, the amount of chelating agent added is configured to be 1.0% to 1.5% of the amount of fly ash added from waste incineration.

[0026] As a further improvement of the present invention, in step S5, the amount of water-soluble polyester fiber added is configured to be 0.5% to 1.0% of the amount of fly ash added from waste incineration.

[0027] As a further improvement of the present invention, in step S5, the vigorous stirring time is 5 min to 7 min.

[0028] As a further improvement of the present invention, in step S6, the extrusion molding pressure is controlled at 0.3MPa to 0.5MPa, and the curing time after dehydration is 3h to 6h.

[0029] Compared with the prior art, the advantages of the present invention are as follows:

[0030] 1. The present invention provides a method for the co-treatment of waste incineration fly ash, municipal sludge, aged waste, and leachate, comprehensively and synergistically treating multiple wastes to achieve waste-to-waste treatment. Considering that the heavy metals Pb (pH 7-10) and Zn (pH 8-11) in waste incineration fly ash are amphoteric metals, a solidification formula is formed through stepwise treatment to enhance the locking of heavy metals. At the same time, the pH value during the comprehensive synergistic chelation treatment of solid waste is controlled between 7 and 10, reducing reagent consumption and achieving the effect of locking heavy metals Pb and Zn, saving production costs and enhancing the compressive strength of the solidified body. Meanwhile, by heating the sludge, the fermentation and odor generation after the sludge co-treatment are prevented, avoiding environmental risks. Furthermore, by adding water-soluble polyester fiber and water-soluble polyvinyl alcohol fiber, the flexural strength of the solidified body is enhanced, preventing cracking of the solidified body.

[0031] 2. The co-treatment method of the present invention for fly ash from waste incineration, municipal sludge, aged waste and leachate contains a large amount of humic substances in the screened material of aged waste. Because the humic substances contain substances such as humin, humic acid and fulvic acid, these substances contain abundant oxygen-containing functional groups such as carboxyl, phenolic, hydroxyl, enol and carbonyl groups, which can adsorb and fix heavy metals such as mercury, nickel, copper and lead, thereby achieving the purpose of assisting in enhancing the heavy metal locking effect. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the process for treating fly ash from waste incineration, municipal sludge, aged waste, and leachate in accordance with the present invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0034] like Figure 1 As shown, the method for treating fly ash from waste incineration, municipal sludge, aged waste, and leachate according to the present invention includes the following steps:

[0035] Step S1: Dry the sieved material of aged waste at 105℃±5℃ for 1-2 hours, then crush it and pass it through a 40-60 mesh sieve to obtain sieved material powder for later use. The sieved material of aged waste contains calcium chloride, silicon dioxide, humus, and other components. By utilizing the unique characteristics of humus, it can help enhance the binding effect of heavy metals.

[0036] Step S2: Mix the fly ash from waste incineration with the sieved powder at a mass ratio of 2 to 3:1, and stir in a sealed space using a high-powered mixer for 15 to 20 seconds to obtain mixture b, which is then set aside.

[0037] Step S3: Add municipal sludge with a water content of 80% ± 2% to the leachate concentrate and condition and stir vigorously for 5 min to 10 min to obtain sludge slurry with a water content of 90% to 95%. Then heat it at a constant temperature of 100℃ ± 5℃ for 20 min to 30 min to kill harmful and gas-producing microorganisms in the sludge to obtain mixed slurry a.

[0038] Step S4: Mix the mixed slurry a and the mixture b at a mass ratio of 1:1 to 1.5 until homogeneous, and control the pH value of the mixture to 7.0 to 10.0.

[0039] Step S5: Add chelating agent and water-soluble polyester fiber to the mixture, mix evenly, and then stir vigorously for 5 min to 7 min to obtain a solidified body; wherein, the amount of chelating agent added is configured at 1.0% to 1.5% of the amount of waste incineration fly ash added, and the amount of water-soluble polyester fiber added is configured at 0.5% to 1.0% of the amount of waste incineration fly ash added.

[0040] Step S6: The solidified body is extruded and molded using a press. If any filtrate is generated, it is recycled. After dehydration, it is cured. After passing inspection, the solidified body is transferred and disposed of in a landfill. The extrusion pressure is controlled between 0.3 MPa and 0.5 MPa, and the curing time after dehydration is 3 to 6 hours.

[0041] Fly ash is highly alkaline due to the need for a large amount of lime slurry in the front-end flue gas desulfurization system. The purpose of this invention is to: form a solidification formula by adding other wastes and taking relevant pretreatment measures, and mix and condition it according to a certain ratio to lock heavy metals in fly ash, thereby reducing the amount of chelating agents required; kill microorganisms in sludge through high-temperature cooking to avoid anaerobic reactions after sludge co-solidification, which could generate gas and affect the safety and stability of the stack; enhance the flexural strength of the solidified body by adding water-soluble polyester fibers to the waste; achieve rapid and stable solidification by using pretreatment methods such as drying and crushing, utilizing minerals such as calcium carbonate and silicon dioxide contained in its components, and adding a solidifying agent; remove heavy metals from the solidified body by adding chelating agents; and further enhance the heavy metal locking effect by utilizing substances such as humic acid, humic acid, and fulvic acid in humic substances.

[0042] Example 1

[0043] According to the technical solution of this invention, the following treatment method is used: Mixed slurry a and mixture b are treated at a mass ratio of 1:1. Municipal sludge is adjusted to 90% slurry to obtain 750g of mixture b. 500g of raw ash is weighed and mixed with 250g of dried garbage undersize powder for 15s to obtain mixed slurry a. After mixing mixed slurry a and mixture b, 7.5g of chelating agent and 2.5g of water-soluble cellulose are added and mixed and stirred vigorously for 5min. Subsequently, the solidified body is dehydrated by extrusion using a press, with the pressure controlled at 0.3MPa. The curing time after dehydration is 4h. If there is any filtrate, it is recycled. The effects on heavy metal Pb, compressive strength, and permeability coefficient are shown in Tables 1 and 2 below.

[0044] Example 2

[0045] According to the processing method of the technical solution of this invention: Mixed slurry a and mixture b are processed at a mass ratio of 1:1.5. 500g of raw ash is weighed and mixed with 200g of dried waste screening powder for 15s to obtain mixed slurry a. Municipal sludge is adjusted to 90% slurry to obtain 1050g of mixture b. Mixed slurry a and mixture b are mixed evenly, and then 10g of chelating agent and 5g of water-soluble cellulose are added and mixed vigorously for 5min. Subsequently, the solidified body is extruded using a press, with the pressure controlled at 0.4MPa. After dehydration, the curing time is 5h. If there is any filtrate, it is recycled and reused. After passing inspection, it is transferred to landfill disposal. The effects of heavy metal Pb, compressive strength, and permeability coefficient are shown in Tables 1 and 2 below.

[0046] Comparative Example 1

[0047] According to the conventional treatment method, weigh 500g of raw ash, add 17.5g of chelating agent and 255g of water, control the moisture content to 33%, stir for 3 to 5 minutes after chelation, and then cure for 3 days before sending it to test for moisture content and heavy metal Pb.

[0048] Comparative Example 2

[0049] According to the conventional treatment method, weigh 500g of raw ash, add 22.5g of chelating agent and 345g of water, control the moisture content to 40%, stir for 3 to 5 minutes after chelation, and then cure for 3 days before sending it to test for moisture content and heavy metal Pb.

[0050] The raw ash in the above embodiments and comparative examples were fly ash from the same batch of waste incineration. After sampling, the ash was mixed evenly and kept for later use.

[0051] Table 1. Physicochemical properties, moisture content, and leaching effect of heavy metal Pb of the solidified body.

[0052]

[0053] Table 2 Strength and Penetration Effect

[0054] Compressive strength (MPa) 0.1 0.6 1.2 1.3 Permeability coefficient (cm / s) <![CDATA[3.12×10 -5 ]]> <![CDATA[5.39×10 -5 ]]> <![CDATA[6.33×10 -7 ]]> <![CDATA[1.53×10 -8 ]]> Maintenance duration (h) 72 72 4 5

[0055] A comparison of the results in Tables 1 and 2 clearly shows that the technical solution of this invention has a positive effect on improving the locking effect of heavy metals and the compressive strength of the solidified body. Furthermore, the solidified body exhibits better forming results than conventional techniques, and the amount of reagent added is significantly lower than in conventional methods. By employing relevant pretreatment methods and supplementing them with reagents, the technical solution of this invention not only ensures that the solidified body meets standard requirements but also achieves the goal of co-processing and disposing of multiple wastes.

[0056] In the technical solution of this invention, pretreatment is used to control the pH value of the fly ash mixture within the range of 7-10 for chelation and solidification treatment, reducing the cost of chelating agents and ensuring the stability of the solidified fly ash. High-temperature heating of the sludge mixture effectively kills harmful and anaerobic microorganisms in the sludge water. The addition of water-soluble polyester fiber as an auxiliary material improves the compressive and flexural strength of the solidified body. Pretreatment methods such as drying and pulverizing enhance the compressive strength of the solidified body. The unique characteristics of humus soil are utilized to further enhance the locking of heavy metals.

[0057] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for co-treating fly ash from waste incineration, municipal sludge, aged waste, and leachate, characterized in that, Includes the following steps: Step S1: Dry the screened material containing humus and aged waste, then crush it to obtain screened material powder for later use; Step S2: Mix the fly ash from waste incineration with the sieved powder at a mass ratio of 2 to 3:1, and then vigorously stir to obtain mixture b, which is ready for use. Step S3: Add municipal sludge with a water content of 80%±2% to the leachate concentrate and condition and stir vigorously to obtain sludge slurry with a water content of 90%~95%. Then heat it at a constant temperature of 100℃±5℃ for 20 min~30 min to kill harmful and gas-producing microorganisms in the sludge and obtain mixed slurry a. Step S4: Mix the mixed slurry a and the mixture b according to the mass ratio and stir evenly, and control the pH value of the mixture to be between 7.0 and 10.0; Step S5: Add chelating agent and water-soluble polyester fiber to the mixture, mix evenly and then stir vigorously to obtain a solidified body; wherein, the amount of chelating agent added is 1.0% to 1.5% of the amount of waste incineration fly ash added. Step S6: The solidified body is extruded and molded using a press. If any filtrate is generated, it is recycled. After dehydration, it is cured. After the solidified body passes inspection, it is transported and disposed of in a landfill.

2. The method for treating fly ash from co-incineration of waste, municipal sludge, aged waste, and leachate according to claim 1, characterized in that, In step S1, the undersize of the aged waste contains calcium chloride, silicon dioxide and humus; the undersize of the aged waste is dried for 1 to 2 hours, and then crushed to a particle size of 40 to 60 mesh.

3. The method for treating fly ash from co-incineration of waste, municipal sludge, aged waste, and leachate according to claim 1, characterized in that, In step S2, the mixture is stirred for 15 to 20 seconds in a closed space using a high-powered mixer to obtain mixture b.

4. The method for treating fly ash from co-incineration of waste, municipal sludge, aged waste, and leachate according to claim 1, characterized in that, In step S3, the vigorous stirring time is 5 min to 10 min.

5. The method for treating fly ash from co-incineration of waste, municipal sludge, aged waste, and leachate according to claim 1, characterized in that, In step S4, the mixed slurry a and the mixture b are mixed and stirred evenly at a mass ratio of 1:1 to 1.

5.

6. The method for treating fly ash from co-incineration of waste, municipal sludge, aged waste, and leachate according to claim 1, characterized in that, In step S5, the amount of water-soluble polyester fiber added is configured to be 0.5% to 1.0% of the amount of fly ash added from waste incineration.

7. The method for treating fly ash from co-incineration of waste, municipal sludge, aged waste, and leachate according to claim 6, characterized in that, In step S5, the vigorous stirring time is 5 min to 7 min.

8. The method for treating fly ash from co-incineration of waste, municipal sludge, aged waste, and leachate according to claim 1, characterized in that, In step S6, the extrusion molding pressure is controlled at 0.3MPa to 0.5MPa, and the curing time after dehydration is 3h to 6h.

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