Method for vacuum preloading-curing combined treatment of sludge

Abstract

The application relates to the field of sludge treatment, and particularly discloses a method for vacuum preloading-curing combined treatment of sludge. The method comprises the following steps: filtering the sludge by using a screen to remove large-particle impurities, adding a flocculating agent and stirring, filtering the sludge by using a screen after standing, adding hydrogen peroxide into the sludge, continuously stirring for 2-4 hours, grinding the sludge in a grinder, mixing the sludge with concrete mortar, adding an ionic soil curing agent, uniformly stirring to obtain sludge-doped concrete, and curing the sludge-doped concrete by using a vacuum preloading method. The method solves the problem that various inorganic matters, organic matters and heavy metals in the sludge affect the performance of concrete.

Description

Technical Field

[0001] This application relates to the field of sludge treatment, and more specifically, it relates to a method for vacuum pre-compression-solidification combined treatment of sludge. Background Technology

[0002] Silt, a common natural sediment, is widely found in aquatic environments such as rivers, lakes, reservoirs, and oceans. It is mainly composed of particles of clay, organic matter, and inorganic matter, and is an important component of aquatic ecosystems. However, with the continuous increase in human activities, the rate of silt formation is accelerating, especially in urban waterways and industrial wastewater discharge outlets, where silt accumulation is more severe. This silt not only occupies aquatic space and affects the natural purification capacity of water bodies, but may also release harmful substances, posing a threat to the aquatic environment and human health.

[0003] Traditional sludge treatment methods often involve simple dumping or landfilling, which not only occupies large amounts of land but also poses potential threats to the environment and human health. Given the strong demand in the building materials market, the application of treated sludge in building materials has broad market prospects. Compared to traditional building materials, transforming sludge into building materials with specific properties through specific treatment processes not only solves the sludge disposal problem and reduces environmental pollution but also achieves resource recycling, providing a new source of raw materials for the building materials industry.

[0004] However, silt has a complex composition, containing various inorganic and organic substances, as well as heavy metals. Organic matter may decompose over time, producing gases or acidic substances, thus affecting the pH value and structural stability of concrete. Heavy metals may also leach out under certain conditions, affecting not only the performance of concrete but also posing potential environmental hazards. Secondly, the physical properties of silt, such as particle size, distribution, and shape, directly affect the structural stability of concrete. Silt particles may form an uneven distribution within the concrete, impacting its mechanical properties and durability. Furthermore, parameters such as the water content and plasticity index of silt also affect the setting time and hardening process of concrete, thus influencing its overall stability. Summary of the Invention

[0005] To address the aforementioned problems, this application provides a method for combined vacuum pre-compression and solidification treatment of sludge.

[0006] This application provides a method for vacuum pre-compression-solidification combined treatment of sludge, which adopts the following technical solution:

[0007] A method for vacuum pre-compression-solidification combined treatment of sludge includes the following steps:

[0008] S1. Take 100-150 parts by weight of silt and filter the silt through a sieve with a mesh size of 1-3mm to remove large particulate impurities.

[0009] S2. Add 10-15 parts of flocculant and stir for 20-40 minutes. After standing for 1-3 hours, filter the sludge using a sieve with a pore size of 1-3 mm.

[0010] S3. Add 1-10 parts of hydrogen peroxide to the sludge and stir continuously at a speed of 30-60 r / min for 2-4 hours;

[0011] S4. Feed the sludge into the grinding mill and grind it until the particle size distribution is 0.01-0.1mm;

[0012] S5. Mix the silt with 300-400 parts of concrete mortar and add 10-30 parts of ion soil curing agent. Stir evenly to obtain silt-mixed concrete.

[0013] S6. Vacuum preloading method is used to solidify the concrete mixed with silt.

[0014] By employing the above technical solutions, using a sieve with a pore size of 1-3mm to filter the sludge effectively removes large particulate impurities, providing a more uniform raw material base for subsequent processing. Adding flocculant and allowing the mixture to settle, followed by further filtration, helps remove suspended solids, fine impurities, and heavy metal ions from the sludge, improving its purity. Introducing hydrogen peroxide treatment oxidizes and decomposes some organic matter in the sludge, reducing its adverse effects on concrete performance and also helping to improve the stability of the sludge. Grinding the sludge to a particle size distribution of 0.01-0.1mm using a grinding mill ensures uniform distribution of sludge particles in the concrete, thereby improving the mechanical properties and durability of the concrete. Controlling the grinding particle size range avoids instability in the concrete structure caused by particles that are too large or too small. Mixing the treated sludge with concrete mortar and adding an ion-modified soil hardener not only improves the strength and stability of the sludge-mixed concrete but also achieves resource recycling and reduces the use of traditional building materials. Using vacuum preloading to solidify silt-mixed concrete can effectively remove excess moisture and gas from the concrete, improve its density and strength, accelerate the hardening process, shorten the construction cycle, and increase construction efficiency.

[0015] Optionally, the flocculant comprises 40-50 parts by weight of polyaluminum chloride, 20-30 parts by weight of polyacrylamide, 5-10 parts by weight of coagulant aid, 15-25 parts by weight of disodium ethylenediaminetetraacetate and 5-15 parts by weight of tartaric acid.

[0016] By employing the above technical solutions, polyaluminum chloride can form large flocs in water, causing impurities to aggregate, flocculate, coagulate, and precipitate. It features rapid formation of large floc particles and excellent sedimentation performance, which helps to efficiently remove suspended solids and colloidal impurities from sludge. Polyacrylamide mainly acts as a bridging adsorption agent through charge interaction, thickening and accelerating the sedimentation process. Its use as a flocculant further improves the removal efficiency of impurities in sludge. Disodium ethylenediaminetetraacetate and tartaric acid, as auxiliary components, can form stable chelates with heavy metal ions in sludge by adjusting the pH of the system and providing complexation. These chelates are not easily hydrolyzed, thus effectively separating heavy metal ions from the sludge, further promoting the removal of impurities and dehydration separation in the sludge.

[0017] Optionally, the coagulant may include either activated silica or bone glue.

[0018] By employing the above technical solution, activated silica works synergistically with other components in the coagulant to form larger and denser flocs, thereby improving solid-liquid separation. This helps to more effectively remove suspended solids and colloidal particles from sludge, thus improving the overall efficiency of sludge treatment. Collagen molecules in bone glue can adsorb and bridge suspended solids and colloidal particles in water, thereby accelerating the formation and sedimentation of flocs.

[0019] Optionally, the concrete mortar composition includes, by weight, 10-30 parts of silicate cement, 10-20 parts of fly ash, 70-100 parts of manufactured sand, 80-120 parts of crushed stone, and 40-60 parts of tap water.

[0020] By adopting the above technical solutions, and through reasonable proportioning and synergistic effects, the performance of concrete mortar has been optimized, and the amount of traditional cementitious materials used has been reduced.

[0021] Optionally, the ionic soil solidifier comprises 20-40 parts by weight of nano-calcium silicate and 40-60 parts by weight of polymethacrylic acid.

[0022] By employing the above-mentioned technical solution, the nano-calcium silicate and polymethyl methacrylate in the ion-based soil hardener can chemically react with harmful substances and pollutants in the sludge to form stable compounds. This not only reduces the release of harmful substances from the sludge but also enhances the bonding ability between the sludge and the concrete matrix, allowing the sludge to better integrate into the concrete and improving the overall structural stability. Nano-calcium silicate has excellent filling and reinforcing properties, filling micro-cracks and pores in the concrete, improving its density and strength. Simultaneously, the adsorption and complexation effects of polymethyl methacrylate can fix harmful substances in the concrete, preventing them from damaging the internal structure and thus improving the concrete's durability. Furthermore, the components in the hardener can interact with moisture in the concrete, regulating the setting time and hardening process, making the concrete easier to construct and shape.

[0023] Optionally, the ion-based soil stabilizer may further include 1-5 parts by weight of soybean isoflavones, 15-25 parts by weight of urease, and 20-30 parts by weight of lignin.

[0024] By employing the above technical solutions, soybean isoflavones possess certain chemical activity, enabling them to react with certain components in the soil and thus further enhance the curing effect of concrete. Urease can catalyze the decomposition of urea into ammonia and carbon dioxide. The ammonia further reacts with components in the silt to form stable compounds, which contribute to soil solidification. Lignin has excellent cementing ability, which can further enhance the connection between soil particles, forming a more stable soil structure.

[0025] Optionally, the specific steps of the vacuum preloading method are as follows:

[0026] Silt is mixed with concrete and poured into a mold, and vertical drainage pipes are buried. A sealing film is laid on the surface of the silt-mixed concrete to ensure that it is isolated from the atmosphere. The sealing film is buried to prevent air leakage.

[0027] A vacuum pump is used to create a vacuum through a water suction pipe embedded in the sand cushion layer, forming a negative pressure inside the mold. The water mixed with the silt in the concrete is then discharged through the drainage pipe.

[0028] By employing the above-mentioned technical solution, the vacuum preloading method effectively removes internal moisture from the silt-mixed concrete under negative pressure, increasing its density and reducing its porosity, which helps improve its strength and stability. Furthermore, the negative pressure environment created during vacuum preloading also helps to further solidify the silt-mixed concrete, improving its overall performance. Vacuum preloading allows for full-load preloading in the initial stages, reducing curing time compared to traditional methods, thus accelerating construction and shortening the construction period.

[0029] Optionally, after step S3 is completed, the sludge needs to be sent into a microwave heating device and treated at a temperature of 150-250℃ for 1-3 hours.

[0030] By employing the above-mentioned technical solution, microwave heating can rapidly heat the sludge, causing its internal moisture to evaporate quickly and achieving efficient dehydration. Treatment at a temperature range of 150-250℃ for 1-3 hours can effectively remove residual moisture and hydrogen peroxide from the sludge. Some organic matter in the sludge undergoes pyrolysis, transforming into more stable compounds. Simultaneously, moisture removal also makes the sludge particles more compact, improving its stability. This enhanced stability helps reduce deformation and sedimentation problems during subsequent treatment and use.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. This application utilizes a sieve to filter sludge, removing large particles and providing uniform raw materials for subsequent processing. Adding flocculants and allowing the sludge to settle and filter further enhances its purity. Introducing hydrogen peroxide oxidizes organic matter, improving stability. Grinding to a specific particle size ensures uniform distribution of the sludge in the concrete, optimizing performance. Mixing with concrete mortar and ion-modified soil hardener recycles resources, enhancing strength and stability. Finally, vacuum preloading for curing removes excess moisture and gas, accelerating hardening and improving construction efficiency.

[0033] 2. This application preferably employs the synergistic effect of polyaluminum chloride and polyacrylamide to rapidly form large flocs, efficiently removing suspended solids and colloidal impurities from the sludge and significantly improving the sludge purity. The addition of disodium ethylenediaminetetraacetate and tartaric acid effectively adjusts the pH value of the system and provides a complexing effect, enabling heavy metal ions to form stable chelates, thereby separating them from the sludge and further enhancing the sludge purification effect.

[0034] 3. This application preferably uses the aforementioned ion-based soil stabilizer components. The synergistic effect of nano-calcium silicate and polymethacrylic acid not only strengthens the bond between silt and concrete but also improves the density and durability of the concrete. The addition of soybean isoflavones, urease, and lignin further enhances the stabilization effect, forming a stable soil structure. Detailed Implementation

[0035] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0036] Preparation example of flocculant

[0037] Preparation Example 1

[0038] A method for preparing a flocculant:

[0039] A flocculant is obtained by mixing 400g of polyaluminum chloride, 200g of polyacrylamide, 50g of bone glue, 150g of disodium ethylenediaminetetraacetate, and 50g of tartaric acid evenly.

[0040] All of the above raw materials are commercially available analytical grade.

[0041] Preparation Example 2

[0042] A method for preparing a flocculant:

[0043] A flocculant is obtained by mixing 460g of polyaluminum chloride, 240g of polyacrylamide, 80g of bone glue, 220g of disodium ethylenediaminetetraacetate, and 80g of tartaric acid evenly.

[0044] All of the above raw materials are commercially available analytical grade.

[0045] Preparation Example 3

[0046] A method for preparing a flocculant:

[0047] A flocculant is obtained by mixing 500g of polyaluminum chloride, 300g of polyacrylamide, 100g of bone glue, 250g of disodium ethylenediaminetetraacetate, and 150g of tartaric acid evenly.

[0048] All of the above raw materials are commercially available analytical grade.

[0049] Preparation Example 4

[0050] A method for preparing a flocculant: the difference from preparation example 2 is that activated silica is selected as the coagulant aid.

[0051] Preparation example of ion-based soil solidification agent

[0052] Preparation Example 5

[0053] A method for preparing an ion-based soil stabilizer:

[0054] 300g of nano-calcium silicate and 500g of polymethyl methacrylate are passed through an 80-mesh sieve and then mixed using a mixer.

[0055] Preparation Example 6

[0056] A method for preparing an ion-based soil stabilizer:

[0057] Pass 300g of nano-calcium silicate and 500g of polymethyl methacrylate through an 80-mesh sieve, then add 30g of soy isoflavones, 200g of urease, and 250g of lignin, and then mix them together using a mixer.

[0058] Example of concrete mortar preparation

[0059] Preparation Example 7

[0060] Mix 20 kg of silicate cement, 15 kg of grade II fly ash, 90 kg of quartzite manufactured sand, 100 kg of crushed stone, and 50 kg of tap water, and then put them into a mixing tank and stir for 30 minutes to obtain concrete mortar.

[0061] Example

[0062] Example 1

[0063] A method for vacuum pre-compression-solidification combined treatment of sludge:

[0064] S1. Take 1 kg of silt and filter it using a 2 mm mesh screen to remove large particles of impurities.

[0065] S2. Add 1 kg of flocculant and stir for 30 min. After standing for 2 h, filter the sludge using a 1 mm sieve.

[0066] S3. Add 0.5 kg of hydrogen peroxide to the sludge and stir continuously at 50 r / min for 3 hours;

[0067] S4. Feed the sludge into the grinding mill and grind it until the particle size distribution is 0.01-0.1mm;

[0068] S5. Mix the silt with 35kg of concrete mortar and add 2kg of ion soil curing agent. Stir well to obtain silt-mixed concrete.

[0069] S6. Pour the silt-mixed concrete into the mold and bury the vertical drainage pipe. Lay a sealing film on the surface of the silt-mixed concrete to ensure that it is isolated from the atmosphere. Bury the sealing film to prevent air leakage. Use a vacuum pump to draw a vacuum through the water suction pipe buried in the sand cushion layer to create a negative pressure in the mold. The water in the silt-mixed concrete is discharged through the drainage pipe.

[0070] The flocculant was prepared in Preparation Example 2, the ion soil solidifier was prepared in Preparation Example 5, and the concrete mortar was prepared in Preparation Example 7.

[0071] Example 2

[0072] A method for vacuum pre-compression-solidification combined treatment of sludge: The difference from Example 1 is that the mass of the sludge used is 15 kg.

[0073] Example 3

[0074] A method for vacuum pre-compression-solidification combined treatment of sludge: The difference from Example 1 is that the mass of the sludge used is 8 kg.

[0075] Example 4

[0076] A method for vacuum pre-compression-solidification combined treatment of sludge: the difference from Example 3 is that the flocculant is prepared by Preparation Example 1.

[0077] Example 5

[0078] A method for vacuum pre-compression-solidification combined treatment of sludge: the difference from Example 3 is that the flocculant is prepared in Preparation Example 3.

[0079] Example 6

[0080] A method for vacuum pre-compression-solidification combined treatment of sludge: the difference from Example 3 is that the flocculant is prepared by Example 4.

[0081] Example 7

[0082] A method for vacuum pre-compression-solidification combined treatment of sludge: the difference from Example 3 is that the ion soil solidifier is prepared by Example 6.

[0083] Example 8

[0084] A method for vacuum pre-compression-solidification combined treatment of sludge: The difference from Example 3 is that after step S3 is completed, the sludge needs to be sent into a microwave heating device and treated at a temperature of 150-250℃ for 1-3 hours.

[0085] Comparative Example

[0086] Comparative Example 1

[0087] A method for vacuum pre-compression-solidification combined treatment of sludge: the difference from Example 3 is that step S2 is not performed.

[0088] Comparative Example 2

[0089] A method for vacuum pre-compression-solidification combined treatment of sludge: the difference from Example 3 is that no ionized soil solidifier is added in step S5.

[0090] Comparative Example 3

[0091] A method for vacuum pre-compression-solidification combined treatment of sludge: The difference from Example 3 is that vacuum pre-compression is not performed in step S6, but natural drying and solidification are used instead.

[0092] Performance testing

[0093] Detection methods

[0094] The silt-mixed concretes obtained in Examples 1-8 and Comparative Examples 1-3 were subjected to mechanical property tests according to the test methods specified in GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and their impermeability was tested according to the methods specified in GB / T 50164-2011 "Standard for Quality Control of Concrete".

[0095] Table 1 Test Results

[0096] 28-day compressive strength / MPa 28-day tensile strength / MPa impermeability grade Example 1 36.5 6.78 P8 Example 2 34.6 4.82 P8 Example 3 36.1 6.65 P8 Example 4 35.7 6.32 P8 Example 5 35.4 6.48 P8 Example 6 34.8 5.74 P8 Example 7 38.8 7.12 P10 Example 8 36.7 6.85 P8 Comparative Example 1 30.7 4.53 P8 Comparative Example 2 27.8 4.32 P4 Comparative Example 3 26.5 4.08 P4

[0097] As can be seen from Example 3 and Comparative Example 1, and Table 1, the flocculant causes the particulate matter in the sludge to rapidly aggregate into larger flocs, which not only improves the dewatering efficiency of the sludge, but also increases the density and strength of the concrete during the subsequent solidification process.

[0098] As can be seen from Example 3 and Comparative Example 2, and Table 1, the ionic curing agent forms a robust structure by chemically reacting with substances in the sludge, thereby improving the strength, compressive strength, and durability of the sludge.

[0099] As can be seen from Example 3 and Comparative Example 3, and in conjunction with Table 1, vacuum preloading treatment can significantly reduce the moisture content of sludge and improve its density and strength. In the preparation of sludge-mixed concrete, vacuum preloading treatment can further consolidate the effect of the ion-curing agent, enabling the sludge-mixed concrete to achieve better stability and durability.

[0100] Based on Examples 1-3 and Table 1, it can be seen that different amounts of sludge will lead to a decrease in the mechanical properties of concrete. Among them, when the amount of sludge is 8 kg, the decrease in the mechanical properties of concrete is very low, and the amount of sludge reuse can be increased without significantly reducing the mechanical properties of concrete.

[0101] As can be seen from Examples 3-6 and Table 1, changing the composition of the flocculant can alter its effectiveness, thereby further improving the mechanical properties of sludge-mixed concrete. Bone glue is a better choice as a coagulant aid.

[0102] As can be seen from Examples 3 and 7 and Table 1, the curing effect of concrete is further enhanced by adding soy isoflavones, urease, and lignin.

[0103] As can be seen from Examples 3 and 8 and Table 1, microwave heating causes the internal moisture to evaporate rapidly, which can effectively remove residual moisture and hydrogen peroxide from the sludge. Some organic matter in the sludge will undergo pyrolysis reaction and be transformed into more stable compounds, making the sludge particles more compact and helping to improve the mechanical properties and durability of sludge-mixed concrete.

[0104] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for treating sludge by vacuum preloading-curing combination, characterized by, The method comprises the following steps: S1, taking 100-150 parts of sludge by weight, filtering the sludge by using a sieve with a pore size of 1-3 mm to remove large particle impurities; S2, adding 10-15 parts of flocculating agent and stirring for 20-40 min, and then filtering the sludge by using a sieve with a pore size of 1-3 mm after standing for 1-3 h; S3, adding 1-10 parts of hydrogen peroxide to the sludge, and continuously stirring at a speed of 30-60 r / min for 2-4 h; S4, feeding the sludge into a grinding machine to grind to a particle size distribution of 0.01-0.1 mm; S5, mixing the sludge with 300-400 parts of concrete mortar, and adding 10-30 parts of ionic soil curing agent, and uniformly stirring to obtain sludge-doped concrete; S6, curing the sludge-doped concrete by using a vacuum preloading method. The components of the flocculating agent include 40-50 parts of polyaluminum chloride, 20-30 parts of polyacrylamide, 5-10 parts of a coagulant aid, 15-25 parts of disodium ethylenediaminetetraacetate, and 5-15 parts of tartaric acid by weight; the coagulant aid includes one of activated silicic acid or bone glue; the components of the ionic soil curing agent include 20-40 parts of nano calcium silicate, 40-60 parts of polymethylacrylic acid, 1-5 parts of soybean isoflavones, 15-25 parts of urease, and 20-30 parts of lignin by weight.

2. The method for vacuum preloading-curing combined treatment of sludge according to claim 1, characterized in that: The components of the concrete mortar include 10-30 parts of Portland cement, 10-20 parts of fly ash, 70-100 parts of machine-made sand, 80-120 parts of gravel, and 40-60 parts of tap water by weight.

3. The method of claim 1, wherein: The specific steps of the vacuum preloading method are as follows: Pouring the sludge-doped concrete into a mold, burying a vertical drainage pipeline, laying a sealing film on the surface of the sludge-doped concrete to ensure that it is isolated from the atmosphere, and burying and pressing the sealing film to prevent air leakage; Using a vacuum pump to extract vacuum through the water absorption pipeline embedded in the sand cushion layer, so that negative pressure is formed in the mold, and the water in the sludge-doped concrete is discharged through the drainage pipeline.

4. The method of claim 1, wherein: After the S3 step is completed, the sludge needs to be fed into a microwave heating device for treatment at a temperature of 150-250℃ for 1-3 h.