Composite flocculant prepared from sludge incineration ash, preparation method and application thereof

Abstract

The application provides a composite flocculant prepared from sludge incineration ash, a preparation method and application thereof, and the composite flocculant comprises the following raw materials in parts by weight: sludge incineration ash hydrolyzed polymer 80%, acid agent 5-15%, and activating agent 5-15%; wherein the sludge incineration ash hydrolyzed polymer is obtained by the following steps: sludge incineration ash is subjected to magnetic separation, grinding, acidification and oxidation treatment, and then hydrolysis polymerization is carried out after adjusting alkalinity. The application uses the industrial solid waste sludge incineration ash with low price to prepare the high-performance flocculant, and the domestic sewage is treated by using the flocculant, the removal rate of suspended solids is good, and the purposes of environment-friendly and waste treatment by waste are achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of solid waste resource utilization, and particularly relates to a composite flocculant prepared from sludge incineration ash, and a preparation method and application thereof. BACKGROUND

[0002] In sewage treatment, the coagulation method can effectively remove suspended and dissolved solids, colloids and organic matters in industrial wastewater, and has the characteristics of wide application range, strong applicability, low cost and the like. FeCl3 and other reagents are used in water treatment in a chemical industry park, and the main components of sludge incineration ash are oxides of Fe and Si. As a solid waste, the traditional treatment method of stacking and landfill not only occupies land, causes waste and pollutes the environment, and therefore the recycling of sludge incineration ash has become the main research direction.

[0003] CN105858838A discloses a sludge incineration source flocculant and a preparation method thereof. The sludge incineration material is used as a raw material, hydrochloric acid is added for dissolution, aluminum-iron chloride solution and filter residue are obtained, the filter residue is mixed with caustic soda for calcination, the obtained calcination product is dissolved with water to obtain a sodium silicate aqueous solution, and the sodium silicate aqueous solution and the aluminum-iron chloride solution are mixed to prepare a polysilicate aluminum-iron flocculant. The preparation process of the flocculant is complex, and high-temperature calcination is required, which consumes a large amount of energy. SUMMARY

[0004] The present application provides a composite flocculant prepared from sludge incineration ash, and a preparation method and application thereof, which is helpful for solid waste recycling and environmental pollution control.

[0005] The technical solution of the present application is a composite flocculant prepared from sludge incineration ash, which comprises the following raw materials by weight: sludge incineration ash hydrolyzed polymer 75-80%, acid agent 5-15%, and activating agent 5-15%; wherein the sludge incineration ash hydrolyzed polymer is obtained by treating sludge incineration ash through magnetic separation, fine grinding, acidification and oxidation, and then adjusting the alkalinity for hydrolysis and polymerization.

[0006] Further preferably, the sludge incineration ash hydrolyzed polymer is 80%, the acid agent is 15%, and the activating agent is 5%.

[0007] Further, the acid agent is mixed by tannic acid, sodium silicate and dodecyl dihydroxyethyl betaine according to a mass ratio of 20-30:55-65:5-20. The mass ratio of tannic acid, sodium silicate and dodecyl dihydroxyethyl betaine in the acid agent is preferably 30:60:10. The activating agent is mixed by sodium alginate, slag powder and petroleum coke desulfurization ash according to a mass ratio of 3-5:45-55:40-52; the mass ratio of sodium alginate, slag powder and petroleum coke desulfurization ash is preferably 5:55:40. The particle size range of the slag powder is 0.05-0.15mm, and the particle size range of the petroleum coke desulfurization ash is 2-4nm.

[0008] The application also relates to a preparation method of the composite flocculant, which comprises the following steps:

[0009] S1, drying sludge incineration ash, then performing magnetic separation to obtain iron-containing magnetic sludge incineration ash, crushing and grinding the iron-containing magnetic sludge incineration ash, adding acid liquid to dissolve, then adding an oxidizing agent to oxidize, adjusting the pH of the filtrate to 1-2 after filtration, performing hydrolysis polymerization, and drying to obtain sludge incineration ash hydrolysis polymer;

[0010] S2, uniformly mixing the sludge incineration ash hydrolysis polymer, the acid agent and the activating agent to obtain the composite flocculant.

[0011] Further, the mass content of iron oxide in the magnetic sludge incineration ash in S1 is above 80%; the acid liquid is hydrochloric acid, and the oxidizing agent is hydrogen peroxide, and NaHCO3 is used to adjust the pH.

[0012] Further, the base degree is controlled to be 65%-70% during the hydrolysis polymerization.

[0013] The application also relates to application of the composite flocculant in sewage treatment.

[0014] Since the sludge incineration ash contains a large amount of heavy metals, the magnetic separation equipment is used for screening before treatment, and only the sludge incineration ash containing magnetic substances is recycled, which helps to improve the purity and quality of the product in the later stage. Through the setting of the magnetic separation step, the efficiency and utilization rate of Fe extraction are higher when the acid liquid is dissolved in the later stage, there is no filter residue, and calcination is not needed, and direct hydrothermal polymerization can be performed.

[0015] The reaction formula related to the sludge incineration ash hydrolysis polymer of the application is as follows:

[0016]

[0017] The magnetic sludge incineration ash is treated by acidification, the iron-containing minerals are dissolved into the acid liquid to form iron salts, Fe 2+ is oxidized to Fe 3+ , and then the pH is adjusted to Fe 3+Hydrolysis generates ferric hydroxide ions, which are then polymerized to form highly polymerized ferric hydroxide.

[0018] The composite flocculant prepared in this invention uses hydrolyzed polymers from sludge incineration ash as the main component, and also includes an acid and an activator. The addition of the acid helps with flocculation and antibacterial activity. Tannic acid itself is a flocculant, and it can react with Ca2+ introduced into the water by the flocculant, as well as Ca2+ already present in the water. 2+ Mg 2+ The combination of these compounds can effectively reduce water hardness. Furthermore, the phenolic hydroxyl groups in tannic acid can bind with the Fe atoms in the hydrolyzed polymers of sludge incineration ash. 3+ Al 3+ Complexation is beneficial to the stability of flocculants, and the specific reactions are shown in formulas (5), (6), and (7). Simultaneously, the presence of weak acids such as tannic acid and dodecyl dihydroxyethyl betaine helps maintain the pH of the treated water. The activated silicic acid in sodium silicate helps form the three-dimensional gel structure of the composite flocculant, enabling the flocculant to maintain its colloidal structure and also giving it a loose network structure, effectively enhancing the flocculation effect.

[0019] ROH→RO - +H + (5)

[0020] RO - +M n →[ROM] n-1 (6)

[0021] M n+ +H2R→RM n-2 +2H + (7)

[0022] The composite flocculant provided by this invention contains an activator with a small particle size, which has high activity and adsorption performance. It can effectively adsorb particles in water and hydrate to form calcium silicate gel, thereby increasing the specific gravity, accelerating the sedimentation rate, and further improving the flocculation performance.

[0023] The flocculant provided by this invention can be used for wastewater treatment, with good removal rates of suspended solids and COD, meeting the "Integrated Wastewater Discharge Standard" (GB 8978-1996). Moreover, it is low in cost and achieves the goal of environmental friendliness and waste-to-waste treatment. Attached Figure Description

[0024] Figure 1 XRD pattern of sludge incineration ash raw material.

[0025] Figure 2 XRD pattern of the hydrolyzed polymer from sludge incineration ash.

[0026] Figure 3FTIR pattern of the sludge incineration ash hydrolyzed polymer.

[0027] Figure 4 Optical microscope pattern (a) and SEM pattern (b) of the sludge incineration ash hydrolyzed polymer. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application.

[0029] The sludge incineration ash in the following examples and comparative examples was taken from a certain riverfront chemical industrial park, which was in the form of fine particles and red-brown in color. After drying, it was ground and sieved, and its main element composition and mineral composition were as shown in Table 1.

[0030] Table 1

[0031]

[0032] The XRD pattern of the above ground and sieved sludge incineration ash raw material is shown in Figure 1 From Figure 1 it can be seen that its main components are Fe2O3 and Fe3O 4。

[0033] Example 1

[0034] Preparation of sludge incineration ash hydrolyzed polymer

[0035] The sludge incineration ash was subjected to magnetic separation, ball milling and sieving, and 100 g of undersize was added to a 6.27 mol / L hydrochloric acid solution at a solid-liquid ratio of 3.45, and reacted in a water bath at 72°C for 71 min. Hydrogen peroxide was added to oxidize Fe 2+ to Fe 3+ , wherein the concentration of hydrogen peroxide was 2.75 mol / L, and then the filtrate was obtained after filtration. NaHCO3 was added to adjust the pH of the filtrate to 2, and hydrolysis and polymerization were carried out for 24 h to obtain a red-brown flocculant solution, which was dried to obtain a sludge incineration ash hydrolyzed polymer.

[0036] The XRD pattern of the polymer is shown in Figure 2 , the XPS pattern is shown in Figure 3 , and the optical microscope pattern and SEM pattern are shown in Figure 4 (a) and (b), respectively. It can be seen that the SPFC flocculant forms a relatively complete and clear dendritic structure, and more particles graft with each other and form a polymer. Further observation of the morphology and structure of the SPFC flocculant by scanning electron microscopy (SEM) shows that the SPFC flocculant has a network structure and a rough and porous surface, which is conducive to adsorbing smaller particles and better capturing pollutants in the wastewater treatment process.

[0037] Preparation of composite flocculant:

[0038] Tannic acid 30 %, sodium silicate 60 % and dodecyl dihydroxyethyl betaine 10 % were mixed as acid agent. Sodium alginate 5 %, slag powder 55 %, and petroleum coke desulfurization ash 40 % were mixed as activator, wherein the particle size range of the slag powder was 0.05-0.15 mm, and the particle size range of the petroleum coke desulfurization ash was 2-4 nm.

[0039] The sludge incineration ash hydrolysis polymer, acid agent and activator were mixed in a ratio of 80 %, 10 % and 5 % to obtain a composite flocculant.

[0040] The above flocculant was used to treat domestic sewage, and the suspended solids of the domestic sewage were 120 mg / L.

[0041] During the treatment, 1 L of domestic sewage was transferred to a beaker, the sewage was stirred at a set stirring speed of 400 r / min for 15 min, 0.05 g of the composite flocculant was added to the sewage, and after 30 min of settling, the supernatant sample was extracted from 2-3 cm below the water surface. The suspended solids were determined using a suspended solids meter at room temperature (25±1 °C) for three times, and under this condition, the removal rate of the flocculant for treating the suspended solids of the domestic sewage was 97.49 %.

[0042] Example 2

[0043] The preparation of the sludge incineration ash hydrolysis polymer was the same as that in Example 1.

[0044] Preparation of composite flocculant:

[0045] Tannic acid 25 %, sodium silicate 55 % and dodecyl dihydroxyethyl betaine 20 % were mixed as acid agent. Sodium alginate 4 %, slag powder 50 %, and petroleum coke desulfurization ash 46 % were mixed as activator, wherein the particle size range of the slag powder was 0.05-0.15 mm, and the particle size range of the petroleum coke desulfurization ash was 2-4 nm.

[0046] The sludge incineration ash hydrolysis polymer, acid agent and activator were mixed in a ratio of 80 %, 10 % and 5 % to obtain a composite flocculant.

[0047] The above flocculant was used to treat domestic sewage, and the specific process was the same as that in Example 1. The removal rate of the composite flocculant for treating the suspended solids of the domestic sewage was 96.42 %.

[0048] Example 3

[0049] The preparation of the sludge incineration ash hydrolysis polymer was the same as that in Example 1.

[0050] Preparation of composite flocculant:

[0051] According to the mass fraction, tannic acid 20 %, sodium silicate 65 % and dodecyl dihydroxyethyl betaine 15 % are mixed as the acid agent. Sodium alginate 3 %, slag powder 45 %, petroleum coke desulfurization ash 52 % are mixed as the activating agent, the particle size range of the slag powder is 0.05~0.15mm, the particle size range of the petroleum coke desulfurization ash is 2~4nm

[0052] The sludge incineration ash hydrolysis polymer, the acid agent and the activating agent are mixed in the ratio of 80 %, 5 % and 15 % to obtain the composite flocculating agent.

[0053] The above flocculating agent is used for treating domestic sewage, and the specific process is the same as that in Example 1. The removal rate of suspended solids of the domestic sewage treated by the composite flocculating agent is 96.56 %.

[0054] Example 4

[0055] The preparation of the sludge incineration ash hydrolysis polymer is the same as that in Example 1.

[0056] Preparation of the composite flocculating agent:

[0057] According to the mass fraction, tannic acid 30 %, sodium silicate 65 % and dodecyl dihydroxyethyl betaine 5 % are mixed as the acid agent. Sodium alginate 5 %, slag powder 55 %, petroleum coke desulfurization ash 40 % are mixed as the activating agent, the particle size range of the slag powder is 0.05~0.15mm, the particle size range of the petroleum coke desulfurization ash is 2~4nm

[0058] The sludge incineration ash hydrolysis polymer, the acid agent and the activating agent are mixed in the ratio of 80 %, 10 % and 10 % to obtain the composite flocculating agent.

[0059] The above flocculating agent is used for treating domestic sewage, and the specific process is the same as that in Example 1. The removal rate of suspended solids of the domestic sewage treated by the composite flocculating agent is 95.89 %.

[0060] Example 5

[0061] The preparation of the sludge incineration ash hydrolysis polymer is the same as that in Example 1.

[0062] Preparation of the composite flocculating agent:

[0063] According to the mass fraction, tannic acid 30 %, sodium silicate 60 % and dodecyl dihydroxyethyl betaine 10 % are mixed as the acid agent. Sodium alginate 5 %, slag powder 55 %, petroleum coke desulfurization ash 40 % are mixed as the activating agent, the particle size range of the slag powder is 0.05~0.15mm, the particle size range of the petroleum coke desulfurization ash is 2~4nm

[0064] The sludge incineration ash hydrolysis polymer, acid agent and activator are mixed in a ratio of 75%, 15% and 10% to obtain a composite flocculant.

[0065] The flocculant is used for treating domestic sewage, and the specific process is the same as that in Example 1. The removal rate of suspended solids in the domestic sewage treated by the composite flocculant is 92.28%.

[0066] Comparative Example 1

[0067] The sludge incineration ash hydrolysis polymer prepared in Example 1 is used for treating domestic sewage. The source and treatment of the domestic sewage are the same as those in Example 1. The removal rate of suspended solids in the domestic sewage is 77.58%.

[0068] Comparative Example 2

[0069] The preparation of the sludge incineration ash hydrolysis polymer is the same as that in Example 1.

[0070] Preparation of the composite flocculant:

[0071] The sludge incineration ash hydrolysis polymer and tannic acid are mixed in a ratio of 80% and 20% by mass fraction to obtain a composite flocculant. The flocculant is used for treating domestic sewage, and the specific process is the same as that in Example 1. The removal rate of suspended solids in the domestic sewage treated by the composite flocculant is 80.46%.

[0072] Comparative Example 3

[0073] The preparation of the sludge incineration ash hydrolysis polymer is the same as that in Example 1.

[0074] Preparation of the composite flocculant:

[0075] The sorbic acid 30%, sodium silicate 60% and dodecyl dihydroxyethyl betaine 10% are mixed as the acid agent by mass fraction. The sodium alginate 5%, slag powder 55% and petroleum coke desulfurization ash 40% are mixed as the activator. The particle size range of the slag powder is 0.05-0.15mm, and the particle size range of the petroleum coke desulfurization ash is 2-4nm.

[0076] The sludge incineration ash hydrolysis polymer, acid agent and activator are mixed in a ratio of 80%, 15% and 5% to obtain a composite flocculant.

[0077] The flocculant is used for treating domestic sewage, and the specific process is the same as that in Example 1. The removal rate of suspended solids in the domestic sewage treated by the composite flocculant is 82.24%.

[0078] Comparative Example 4

[0079] The preparation of the sludge incineration ash hydrolysis polymer is the same as that in Example 1.

[0080] Preparation of the composite flocculant:

[0081] According to the mass fraction, tannic acid 45%, sodium silicate 50% and dodecyl dihydroxyethyl betaine 5% are mixed as the acid agent. Sodium alginate 5%, slag powder 55%, petroleum coke desulfurization ash 40% are mixed as the activating agent, the particle size range of the slag powder is 0.05-0.15mm, and the particle size range of the petroleum coke desulfurization ash is 2-4nm.

[0082] The sludge incineration ash hydrolysis polymer, the acid agent and the activating agent are mixed in a ratio of 80%, 15% and 5% to obtain the composite flocculating agent.

[0083] The flocculating agent is used for treating domestic sewage, and the specific process is the same as that in Example 1. The removal rate of suspended solids of the domestic sewage treated by the composite flocculating agent is 81.39%.

[0084] Comparative Example 5

[0085] The preparation of the sludge incineration ash hydrolysis polymer is the same as that in Example 1.

[0086] Preparation of the composite flocculating agent:

[0087] According to the mass fraction, tannic acid 30%, sodium silicate 60% and dodecyl dihydroxyethyl betaine 10% are mixed as the acid agent.

[0088] The sludge incineration ash hydrolysis polymer and the acid agent are mixed in a ratio of 80% and 20% to obtain the composite flocculating agent.

[0089] The flocculating agent is used for treating domestic sewage, and the specific process is the same as that in Example 1. The removal rate of suspended solids of the domestic sewage treated by the composite flocculating agent is 86.23%.

[0090] Comparative Example 6

[0091] The preparation of the sludge incineration ash hydrolysis polymer is the same as that in Example 1.

[0092] Preparation of the composite flocculating agent:

[0093] According to the mass fraction, tannic acid 30%, sodium silicate 60% and dodecyl dihydroxyethyl betaine 10% are mixed as the acid agent. Slag powder 60% and petroleum coke desulfurization ash 40% are mixed as the activating agent, the particle size range of the slag powder is 0.05-0.15mm, and the particle size range of the petroleum coke desulfurization ash is 2-4nm.

[0094] The sludge incineration ash hydrolysis polymer, the acid agent and the activating agent are mixed in a ratio of 80%, 15% and 5% to obtain the composite flocculating agent.

[0095] The flocculant is used for treating domestic sewage, and the specific process is the same as that in Embodiment 1. The removal rate of suspended solids of the composite flocculant for treating domestic sewage is 90.45%.

[0096] Comparative Example 7

[0097] The preparation of the sludge incineration ash hydrolyzed polymer is the same as that in Embodiment 1.

[0098] Preparation of the composite flocculant:

[0099] The sodium alginate 5%, the slag powder 55% and the petroleum coke desulfurization ash 40% are mixed as the activator according to the mass fraction. The particle size range of the slag powder is 0.05-0.15 mm, and the particle size range of the petroleum coke desulfurization ash is 2-4 nm.

[0100] The sludge incineration ash hydrolyzed polymer and the activator are mixed according to the ratio of 80% and 20% to obtain the composite flocculant.

[0101] The flocculant is used for treating domestic sewage, and the specific process is the same as that in Embodiment 1. The removal rate of suspended solids of the composite flocculant for treating domestic sewage is 82.59%.

[0102] Comparative Example 8

[0103] The preparation of the sludge incineration ash hydrolyzed polymer is the same as that in Embodiment 1.

[0104] Preparation of the composite flocculant:

[0105] The tannic acid 30%, the sodium silicate 60% and the dodecyl dihydroxyethyl betaine 10% are mixed as the acid agent according to the mass fraction. The sodium alginate is the activator.

[0106] The sludge incineration ash hydrolyzed polymer, the acid agent and the activator are mixed according to the ratio of 80%, 15% and 5% to obtain the composite flocculant.

[0107] The flocculant is used for treating domestic sewage, and the specific process is the same as that in Embodiment 1. The removal rate of suspended solids of the composite flocculant for treating domestic sewage is 80.22%.

[0108] It should be noted that the above-mentioned embodiments should be understood as illustrative rather than limiting the protection scope of the present application, and the protection scope of the present application is subject to the claims. Some non-essential improvements and adjustments made by those skilled in the art without departing from the essence and scope of the present application still belong to the protection scope of the present application.

Claims

1. A composite flocculant prepared using sludge incineration ash, characterized in that, The raw materials include, by weight, the following: 75-80% hydrolyzed polymer from sludge incineration ash, 5-15% acid, and 5-15% activator; wherein the hydrolyzed polymer from sludge incineration ash is obtained by hydrolyzing and polymerizing sludge incineration ash after magnetic separation, grinding, acidification, and oxidation treatment, followed by adjustment to alkalinity; the acid is a mixture of tannic acid, sodium silicate, and dodecyl dihydroxyethyl betaine in a mass ratio of 20-30:55-65:5-20; and the activator is a mixture of sodium alginate, slag powder, and petroleum coke desulfurization ash in a mass ratio of 3-5:45-55:40-52.

2. The composite flocculant according to claim 1, characterized in that: The sludge incineration ash residue contains 80% hydrolyzed polymer, 15% acid, and 5% activator.

3. The composite flocculant according to claim 1, characterized in that: The mass ratio of tannic acid, sodium silicate, and dodecyl dihydroxyethyl betaine in the acid is 30:60:

10.

4. The composite flocculant according to claim 1, characterized in that: The particle size range of slag powder is 0.05~0.15mm, and the particle size range of petroleum coke desulfurization ash is 2~4nm.

5. The composite flocculant according to claim 4, characterized in that: The mass ratio of sodium alginate, slag powder, and petroleum coke desulfurization ash in the activator is 5:55:

40.

6. The method for preparing the composite flocculant according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. The sludge incineration ash is dried, and then magnetic separation is performed to obtain iron-containing magnetic sludge incineration ash. The ash is crushed and ground, dissolved in acid, and then oxidized by adding an oxidant. After filtration, the pH of the filtrate is adjusted to 1-2, and hydrolysis and polymerization are carried out. After drying, the sludge incineration ash hydrolysis polymer is obtained. S2. Mix the hydrolyzed polymer, acid, and activator in the sludge incineration ash residue to obtain a composite flocculant.

7. The preparation method according to claim 6, characterized in that: The iron oxide content in the magnetic sludge incineration ash of S1 is above 80% by mass; the acid solution is hydrochloric acid, the oxidant is hydrogen peroxide, and the pH is adjusted by NaHCO3.

8. The preparation method according to claim 6, characterized in that: During hydrolysis polymerization, the basicity should be controlled at 65%~70%.

9. The application of the composite flocculant according to any one of claims 1 to 4 in wastewater treatment.

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