Comprehensive waste treatment method

Abstract

The invention provides a comprehensive waste treatment method, and belongs to the technical field of waste treatment.The comprehensive waste treatment method comprises the following steps that S1, household waste is incinerated in an incinerator, and household waste incineration fly ash (fly ash for short) is obtained; s2, the fly ash obtained in the step S1 is subjected to thermal pretreatment, and modified fly ash is obtained; s3, carrying out landfill composting by using the kitchen garbage to generate leachate; s4, carrying out primary washing and filter pressing dehydration on the modified fly ash obtained in the step S2 by adopting the percolate obtained in the step S3; s5, carrying out secondary washing and filter-pressing dehydration on the modified fly ash dehydrated in the step S4 by adopting the leachate obtained in the step S3 to obtain dechlorinated fly ash and wastewater; and S6, respectively recovering the dechlorinated fly ash and the wastewater. Through the comprehensive waste treatment method, the chlorine element in the fly ash can be effectively removed, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of garbage disposal, and in particular to a comprehensive waste disposal method. Background Art

[0002] According to current waste sorting principles, waste management parks typically have multiple different waste treatment areas. Among these, the areas primarily responsible for urban waste disposal include food waste treatment plants and municipal waste incineration power plants. Landfill composting is the primary method for treating food waste. However, due to its high moisture content, landfill composting easily produces large amounts of leachate, which is expensive to treat. If not properly handled, it can pollute groundwater and surface water systems, severely harming the ecological environment. For municipal waste, incineration is currently the primary method. However, the fly ash produced by incineration contains significant amounts of heavy metals and salt compounds, particularly sodium chloride (NaCl) and potassium chloride (KCl). These components make the fly ash highly corrosive and toxic, making it difficult to directly recycle or discharge. Therefore, an environmentally friendly waste treatment method is urgently needed. Summary of the Invention

[0003] The purpose of the present invention is to provide an environmentally friendly garbage disposal method for kitchen waste and domestic waste.

[0004] To achieve the above objectives, the present invention provides a method for comprehensive waste treatment, comprising the following steps: S1: Incinerate domestic waste in an incinerator to obtain fly ash S2: performing thermal pretreatment on the fly ash obtained in step S1 to obtain modified fly ash; S3: using food waste for landfill composting to generate leachate; S4: using the leachate obtained in step S3 to perform a first washing and filter press dehydration on the modified fly ash obtained in step S2; S5: using the leachate obtained in step S3 to perform a second washing and filter press dehydration on the modified fly ash dehydrated in step S4 to obtain dechlorinated fly ash and wastewater; S6: Recover dechlorinated fly ash and wastewater separately.

[0005] Preferably, in step S2, the temperature of the heat pretreatment is 200-600° C., and the duration of the heat pretreatment is 10-90 minutes.

[0006] Through thermal pretreatment, minerals such as silicates and aluminates in fly ash can undergo partial decomposition or crystal transformation, destroying the density of the original structure. At the same time, thermal pretreatment can soften the glass phase in fly ash when heated, enhance its fluidity, and release the chlorides wrapped in the glass phase. At the same time, thermal pretreatment can cause local fracture of the glass network structure of the glass phase, providing a channel for the subsequent diffusion of chlorides.

[0007] Preferably, in step S2, the heat source for thermal pretreatment is the waste heat generated by the incineration of domestic waste in step S1.

[0008] Preferably, the step S4 further comprises the following steps: S42: After dehydration is completed, lactic acid fermentation liquid is added to the modified fly ash, and the mixture is filtered and dehydrated.

[0009] Preferably, the mass ratio of the lactic acid fermentation broth to the modified fly ash is 1:1.

[0010] In order to further reduce the chloride content in fly ash, the present invention adds lactic acid fermentation liquid to the modified fly ash after the first dehydration, using the hydroxyl group (-OH) and carboxylic acid group (-COOH) in the lactic acid molecule as ligands to combine with the metal ions in the fly ash to form a stable water-soluble complex, thereby achieving further chlorine removal.

[0011] Preferably, in step S4, the mass ratio of leachate to modified fly ash is (1-8):1.

[0012] Preferably, the pressure of the filter press dehydration is 0.4-0.8 MPa.

[0013] Preferably, in step S5, the mass ratio of leachate to modified fly ash is (0.5-3):1.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention utilizes waste heat from waste incineration to pre-treat fly ash, effectively recovering heat energy and reducing additional energy consumption. Leachate generated from kitchen waste landfill composting serves as a fly ash detergent, effectively realizing waste resource utilization while providing a leachate treatment method and offering a new approach to comprehensive waste treatment. 2. In the comprehensive waste treatment method provided by the present invention, efficient dechlorination can be achieved through double washing and lactic acid washing, and the fly ash after dechlorination can be directly used for resource utilization; 3. The present invention couples the incineration, landfill composting and fly ash treatment links of waste treatment for the first time, avoiding the secondary pollution problem of leachate or fly ash generated by traditional single treatment methods, and effectively improving the economic and environmental benefits of waste treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 These are the chlorine content measurement results of the dechlorinated fly ash obtained in each example and comparative example in Example 3 of the present invention. DETAILED DESCRIPTION

[0016] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0017] It should be noted that the endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0018] As described in the background technology, currently, leachate generated by landfill composting of kitchen waste pollutes the environment, and fly ash generated by incineration of domestic waste cannot be directly discharged due to the presence of heavy metals and chloride salts. Based on this, a specific embodiment of the present invention provides a comprehensive waste treatment method, which includes the following steps: S1: Incinerating domestic waste in an incinerator to obtain fly ash; S2: performing thermal pretreatment on the fly ash obtained in step S1 to obtain modified fly ash; S3: using food waste for landfill composting to generate leachate; S4: using the leachate obtained in step S3 to perform a first washing and filter press dehydration on the modified fly ash obtained in step S2; S42: After dehydration is completed, lactic acid fermentation liquid is added to the modified fly ash, and dehydration is performed by filter pressing; S5: using the leachate obtained in step S3 to perform a second washing and filter press dehydration on the modified fly ash dehydrated in step S4 to obtain dechlorinated fly ash and wastewater; S6: Recover dechlorinated fly ash and wastewater separately.

[0019] In step S2 of the above embodiment, the temperature of the thermal pretreatment is 200-600° C., and the duration of the thermal pretreatment is 10-90 min.

[0020] More specifically, in the above embodiment, the heating rate of the heat treatment is 5-20° C. / min, and the cooling method of the heat treatment is natural cooling.

[0021] The fly ash produced by traditional waste incineration is primarily composed of calcium salts, silicates, aluminates, and glass phases formed during the incineration process. These minerals form a dense structure upon cooling after melting at high temperatures, encapsulating some chlorides (such as NaCl, KCl, and heavy metal chlorides) in the lattice or glass phase, creating a physical and chemical barrier that makes traditional water washing difficult to effectively remove. The comprehensive waste treatment method provided in the specific embodiments of the present invention destroys the crystal structure and glass phase of the fly ash through thermal pretreatment, exposing the chlorides directly to the fly ash surface and enabling their direct removal through water washing. Furthermore, washing the modified fly ash with lactic acid fermentation broth can effectively remove some heavy metal chlorides.

[0022] The comprehensive waste treatment method provided by the above-mentioned embodiment can effectively remove heavy metals and chlorides from fly ash, and the obtained dechlorinated fly ash can be directly recycled for resource utilization and used in the preparation of building materials such as cement. At the same time, the above-mentioned embodiment uses leachate generated by kitchen waste landfill to clean the modified fly ash. Since the leachate is acidic, it can effectively neutralize the pH value of the alkaline fly ash. In addition, the acidic leachate can destroy the modified fly ash particles, further improving the chloride removal effect of the fly ash.

[0023] In step S2 of the above embodiment, the heat source for the thermal pretreatment is the waste heat generated by the incineration of domestic waste in step S1.

[0024] In step S42 of the above embodiment, the mass ratio of the lactic acid fermentation liquid to the modified fly ash is 1:1.

[0025] In step S5 of the above embodiment, the mass ratio of leachate to modified fly ash is (0.5-3):1.

[0026] In the above embodiment, the pressure of the filter press dehydration is 0.4-0.8 MPa.

[0027] The technical solutions of the present invention are further described below by specific examples, and unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventional understandings are defined herein for the purpose of illustrating or facilitating quoting, and such definitions herein should not be construed as representing significant differences from conventional understandings in the art. The technical methods described herein or cited are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available reagents and instruments is carried out according to the schemes and parameters provided by the manufacturer.

[0028] Example 1 S1: Incinerating domestic waste in an incinerator to obtain fly ash; S2: Using the waste heat of the incinerator, the fly ash obtained in step S1 is subjected to thermal pretreatment to obtain modified fly ash. The thermal pretreatment temperature is 600°C and the thermal pretreatment time is 60 minutes. S3: Using kitchen waste for landfill composting, leachate is generated, and the pH of the leachate is 3.9; S4: using the leachate obtained in step S3 to perform a first washing and filter pressing dehydration on the modified fly ash obtained in step S2. The first washing method is elution, and the mass ratio of leachate to modified fly ash is 8:1. S42: After dehydration, the modified fly ash is washed and dehydrated by filter pressing using a lactic acid fermentation liquid having a pH of 3.5 and a lactic acid concentration of 10 g / L; S5: using the leachate obtained in step S3 to perform a second washing and filter press dehydration on the modified fly ash dehydrated in step S42 to obtain dechlorinated fly ash and wastewater. The second washing method is elution, and the mass ratio of leachate to modified fly ash is 3:1; S6: Recover dechlorinated fly ash and wastewater separately.

[0029] Example 2 S1: Incinerating domestic waste in an incinerator to obtain fly ash; S2: Using the waste heat of the incinerator, the fly ash obtained in step S1 is subjected to thermal pretreatment to obtain modified fly ash. The thermal pretreatment temperature is 300° C. and the thermal pretreatment time is 90 minutes. S3: Using kitchen waste for landfill composting, leachate is generated, and the pH of the leachate is 3.9; S4: using the leachate obtained in step S3 to perform a first washing and filter pressing dehydration on the modified fly ash obtained in step S2. The first washing method is elution, and the mass ratio of the leachate to the modified fly ash is 5:1; S42: After dehydration, the modified fly ash is washed and filter-pressed with a lactic acid fermentation liquid having a pH of 3.5 and a lactic acid concentration of 10 g / L; S5: using the leachate obtained in step S3 to perform a second washing and filter press dehydration on the modified fly ash dehydrated in step S42 to obtain dechlorinated fly ash and wastewater. The second washing method is elution, and the mass ratio of leachate to modified fly ash is 1:1; S6: Recover dechlorinated fly ash and wastewater separately.

[0030] Comparative Example 1 S1: Incinerating domestic waste in an incinerator to obtain fly ash; S2: Using the waste heat of the incinerator, the fly ash obtained in step S1 is subjected to thermal pretreatment to obtain modified fly ash. The thermal pretreatment temperature is 600°C and the thermal pretreatment time is 60 minutes. S3: washing the modified fly ash obtained in step S2 with pure water for the first time and performing filter pressing to dehydrate it. The first washing method is elution, and the mass ratio of water to modified fly ash is 8:1; S32: After dehydration, the modified fly ash is washed and filter-pressed with a lactic acid fermentation liquid having a pH of 3.5 and a lactic acid concentration of 10 g / L; S4: washing the modified fly ash dehydrated in step S32 for a second time with pure water and performing filter pressing to obtain dechlorinated fly ash and wastewater. The second washing is performed by elution, and the mass ratio of water to modified fly ash is 3:1. S5: Recover dechlorinated fly ash and wastewater separately.

[0031] Comparative Example 2 A1: Incinerate domestic waste in an incinerator to obtain fly ash; A2: The fly ash obtained in step A1 is subjected to a first washing and filter pressing dehydration using pure water. The first washing method is elution, and the mass ratio of water to fly ash is 8:1; A3: The fly ash dehydrated in step A2 is subjected to a second washing and filter pressing dehydration with pure water to obtain dechlorinated fly ash and wastewater. The second washing method is elution, and the mass ratio of water to fly ash is 3:1; A4: Recover dechlorinated fly ash and wastewater separately.

[0032] Comparative Example 3 A1: Incinerate domestic waste in an incinerator to obtain fly ash; A2: The fly ash obtained in step A1 is subjected to a first washing and filter pressing dehydration using the leachate in Example 1. The first washing method is elution, and the mass ratio of leachate to fly ash is 8:1; A3: The fly ash dehydrated in step A2 is subjected to a second washing and filter pressing dehydration using the leachate from Example 1 to obtain dechlorinated fly ash and wastewater. The second washing method is elution, and the mass ratio of leachate to fly ash is 3:1. A4: Recover dechlorinated fly ash and wastewater separately.

[0033] Comparative Example 4 B1: Incinerate domestic waste in an incinerator to obtain fly ash; B2: Grinding the fly ash obtained in step B1 using a ball mill to obtain modified fly ash, wherein the average particle size of the modified fly ash is 40 μm; B3: The modified fly ash obtained in step B2 is subjected to a first washing and filter pressing dehydration with pure water. The first washing method is elution, and the mass ratio of water to modified fly ash is 8:1; B4: The modified fly ash dehydrated in step B3 is subjected to a second washing and filter pressing dehydration with pure water to obtain dechlorinated fly ash and wastewater. The second washing method is elution, and the mass ratio of water to modified fly ash is 3:1; B5: Recover dechlorinated fly ash and wastewater separately.

[0034] Comparative Example 5 B1: Incinerate domestic waste in an incinerator to obtain fly ash; B2: Grinding the fly ash obtained in step B1 using a ball mill to obtain modified fly ash, wherein the average particle size of the modified fly ash is 40 μm; B3: The modified fly ash obtained in step B2 is subjected to a first washing and filter pressing dehydration using the leachate in Example 1. The first washing method is elution, and the mass ratio of leachate to modified fly ash is 8:1. B4: The modified fly ash dehydrated in step B3 is subjected to a second washing and filter pressing dehydration using the leachate in Example 1 to obtain dechlorinated fly ash and wastewater. The second washing method is elution, and the mass ratio of leachate to modified fly ash is 3:1; B5: Recover dechlorinated fly ash and wastewater separately.

[0035] Example 3 Dechlorinated fly ash characterization The dechlorinated fly ash obtained in Example 1 and Comparative Examples 1 to 5 was collected, and the chlorine content in the dechlorinated fly ash obtained in each treatment method was measured. The measurement results are as follows: Figure 1 As shown. Figure 1 As can be seen, after using the modified fly ash modified by the thermal pretreatment provided by the present invention and washing with leachate, the chloride content in the dechlorinated fly ash is 0.82%, which is much lower than that of other treatment methods. This shows that the comprehensive waste treatment method provided by the present invention can effectively reduce chloride content in fly ash and has broad application prospects.

[0036] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A comprehensive waste treatment method, characterized in that: The following steps are involved: S1: Incinerating domestic waste in an incinerator to obtain fly ash; S2: performing thermal pretreatment on the fly ash obtained in step S1 to obtain modified fly ash; S3: using food waste for landfill composting to generate leachate; S4: using the leachate obtained in step S3 to perform a first washing and filter press dehydration on the modified fly ash obtained in step S2; S5: using the leachate obtained in step S3 to perform a second washing and filter press dehydration on the modified fly ash dehydrated in step S4 to obtain dechlorinated fly ash and wastewater; S6: Recover dechlorinated fly ash and wastewater separately.

2. The comprehensive waste treatment method according to claim 1, characterized in that: In step S2, the temperature of the heat pretreatment is 200-600° C., and the duration of the heat pretreatment is 10-90 minutes.

3. The comprehensive waste treatment method according to claim 1, characterized in that: In step S2, the heat source for the thermal pretreatment is the waste heat generated by the incineration of domestic waste in step S1.

4. The comprehensive waste treatment method according to claim 1, wherein: The step S4 further comprises the following steps: S42: After dehydration is completed, lactic acid fermentation liquid is added to the modified fly ash, and the mixture is filtered and dehydrated.

5. The comprehensive waste treatment method according to claim 4, characterized in that: The mass ratio of the lactic acid fermentation liquid to the modified fly ash is 1:

1.

6. The comprehensive waste treatment method according to claim 1, wherein: In step S4, the mass ratio of leachate to modified fly ash is (1-8):

1.

7. The comprehensive waste treatment method according to claim 1, characterized in that: The pressure of filter press dehydration is 0.4-0.8MPa.

8. The comprehensive waste treatment method according to claim 1, wherein: In step S5, the mass ratio of leachate to modified fly ash is (0.5-3):1.

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