Flocculation-electroosmosis-solidification integrated sludge treatment method

Abstract

The invention relates to the technical field of sludge treatment, and provides a flocculation-electroosmosis-solidification integrated sludge treatment method which comprises the following steps: collecting sludge on site, filling the pretreated sludge into a stirring barrel, and stirring with a stirrer while adding tap water at a constant speed for several times until the required water content is reached; adding a flocculating agent into the stirring barrel, and uniformly stirring; filling the sludge obtained after water removal into an electroosmosis device for electroosmosis treatment; adding a curing agent into the sludge subjected to flocculation electroosmosis treatment to ensure that a stable blocky structure is formed; by means of charge neutralization of polyacrylamide and the adsorption bridging effect of a molecular long chain, the long chain structure and soil particles in sludge are cemented to form large aggregates, the aggregates collide with one another and sink in an accelerated mode under the action of gravity, ions are pushed to move in soil through electroosmosis by means of an electric field, and water and solid particles can be separated easily; by adding the curing agent, the sludge is cured into a firm structure, and the adverse effect on the environment is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and in particular to a flocculation-electroosmosis-solidification integrated sludge treatment method. Background Art

[0002] The traditional disposal methods of engineering waste sludge mainly include mud dumping and landfilling. Although they can handle a large amount of waste sludge, they have a series of problems such as environmental pollution, occupation of a large amount of land, long time consumption and high cost, which seriously violates the strategic goal of "green and low-carbon development" and has been gradually abandoned. The use of stabilization and solidification technology to effectively treat engineering waste sludge and use solidified waste sludge for embankment reinforcement, artificial island casting and roadbed filling not only avoids secondary pollution of dredged sludge, but also realizes the recycling of waste sludge. Therefore, stabilization and solidification technology has become the primary way to treat engineering waste sludge. General solidification technology uses the physical and chemical reaction of curing agents (such as cement, fly ash, alkali slag, flocculants, phosphogypsum, etc.) with water, clay minerals and pollutants in waste sludge to achieve the purpose of converting water, stabilizing pollutants and improving strength. It has the advantages of wide applicability and high construction efficiency. However, this single solidification technology faces two major problems when applied: ① The effectiveness of the curing agent is greatly reduced when it comes into contact with water, and the curing effect is not ideal; ② High-water content waste sludge requires a large amount of curing agent, and the treatment cost is too high. These problems have greatly restricted the application of single solidification technology in high-water content waste mud, and are the key technical bottlenecks that urgently need to be solved in the current engineering waste mud stabilization and solidification technology. Summary of the invention

[0003] In order to solve the above problems, the present invention provides the following technical solutions:

[0004] The present invention provides a flocculation-electroosmosis-solidification integrated sludge treatment method, comprising:

[0005] (1) collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0006] (2) Pour the pretreated sludge into a mixing barrel, add tap water at a constant speed in batches while stirring with a mixer until the required water content is reached; add flocculant into the mixing barrel, stir evenly, and let stand for 6 hours;

[0007] (3) filling the sludge obtained after dewatering in step 2 into an electroosmosis device for electroosmosis treatment, the electroosmosis time being 6-24 hours;

[0008] (4) Adding a solidifying agent to the sludge treated by flocculation and electroosmosis to ensure the formation of a stable bulk structure and reduce the release of harmful substances; performing a strength test on the formed bulk structure to ensure the formation of a stable bulk structure and obtain recyclable sludge.

[0009] Furthermore, the flocculant includes polyacrylamide and chitosan.

[0010] Furthermore, the polyacrylamide is 0.2% to 0.35% of the mass of the pretreated sludge; the chitosan is 1‰ to 2‰ of the mass of the pretreated sludge. Polyacrylamide and chitosan physically interact with the sludge particles through charge neutralization and the "adsorption and bridging" effect of long molecular chains, wherein the long chain structure is cemented with the soil particles in the sludge to form large aggregates, which allow the sludge particles to quickly flocculate into agglomerates, and the spatial structure between the sludge particles is changed through the flocculation effect, and the aggregates collide with each other and accelerate the sinking under the action of gravity. Both polyacrylamide and chitosan have flocculation effects, but their mechanisms of action are different. Polyacrylamide is mainly based on adsorption and bridging effects, while chitosan is mainly based on charge neutralization and adsorption and bridging effects.

[0011] Furthermore, the curing agent is a composite curing agent.

[0012] Furthermore, the curing agent includes carbide slag and wood ash.

[0013] Furthermore, the carbide slag accounts for 10% to 15% of the mass of the pre-treated sludge; and the wood ash accounts for 15% to 18% of the mass of the pre-treated sludge.

[0014] Furthermore, the electroosmosis device includes a soil sample tank, a water collection tank, an electrode plate and a DC power supply, the electrode plate includes an anode plate and a cathode plate arranged on both sides of the soil sample tank, and the anode plate and the cathode plate are respectively connected to the DC power supply through wires; the electroosmosis treatment refers to turning on the DC power supply to allow the water in the solidified sludge to flow from the anode to the cathode and be discharged.

[0015] Furthermore, when the soil sample tank is an indoor model box, a GW GPS3303c DC power supply with a limit value of 30V and 3A and a cross-sectional area of ​​1mm 2 of copper wire.

[0016] Furthermore, when the soil sample tank is an outdoor open space, a DC power supply with a limit of 240V and 1A and a cross-sectional area of ​​5mm 2 of copper wire.

[0017] Furthermore, the electrode plate is made of an iron electrode plate or a copper electrode plate with a size of 100 mm×100 mm.

[0018] The present invention has the following beneficial effects:

[0019] (1) The present invention utilizes the charge neutralization and molecular long chain "adsorption bridging" effect of polyacrylamide, wherein the long chain structure is bonded with the soil particles in the sludge to form large aggregates, which collide with each other and sink faster under the action of gravity. Electroosmosis uses the electric field to drive ions to move in the soil, which helps to separate water and solid particles; in addition, the particle structure of the sludge changes, and larger pores are formed between the flocs, which is beneficial to the subsequent dehydration process. The sludge is solidified into a solid structure by adding a curing agent, reducing the adverse effects on the environment. By improving the particle structure and electrical properties of the sludge, the electroosmosis process is facilitated to proceed smoothly and the electroosmosis dehydration efficiency is improved; the electroosmosis process further compacts the flocculated flocs, promotes the discharge of water, and makes the curing agent more evenly distributed in the sludge under the action of the electric field, thereby enhancing the curing effect; the three work synergistically to significantly improve the effect and efficiency of sludge treatment.

[0020] (2) The polyacrylamide and chitosan in the present invention reduce the viscosity of the sludge and enhance its fluidity, thereby facilitating transportation and subsequent processing operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the electroosmosis device of the present invention.

[0022] Figure 2 It is a flow chart of sludge treatment in the present invention. DETAILED DESCRIPTION

[0023] The specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. It should be pointed out that the embodiments are only specific explanations of the invention and should not be regarded as limitations of the invention. The purpose of the embodiments is to enable those skilled in the art to better understand and reproduce the technical solutions of the present invention. The protection scope of the present invention shall still be based on the scope defined by the claims.

[0024] In order to better illustrate the technical effect of the present solution, the present invention is described below in conjunction with embodiments.

[0025] like Figure 1 As shown, the silt collected in the embodiment experiment and the electroosmosis device used are consistent. The soil sample tank 1 is a piece of open space by the river. The electroosmosis electrode is composed of iron electrode plates with specifications of 600mm×600mm×5mm, which are spliced ​​side by side to form the anode plate 3 and cathode plate 4 on both sides of the soil sample tank. The power supply adopts a DC power supply 5 with a limit of 240V and 1A, an initial voltage of 30V, and a 5 square millimeter copper wire. The electroosmosis device includes a soil sample tank 1, an electrode plate and a DC power supply 5. The electrodes include an anode plate 3 and a cathode plate 4 arranged on both sides of the soil sample tank 1. The anode plate and the cathode plate are respectively connected to the DC power supply 5 through wires, wherein the cathode plate 4 has multiple rows of cathode drainage holes 8, which are conducive to drainage.

[0026] Example 1

[0027] like Figure 2 As shown, this embodiment provides a flocculation-electroosmosis-solidification integrated sludge treatment method, comprising:

[0028] S1, collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0029] S2, fill the pre-treated sludge into a mixing barrel, add tap water at a uniform speed and stir with a mixer until the required water content is reached; add flocculant to the mixing barrel, stir evenly, and let it stand for 6 hours; by utilizing the charge neutralization and molecular long chain "adsorption bridging" effect of APAM, the adsorbed and suspended fine solid soil particles are quickly dehydrated and flocculated and deposited, and then voltage is applied to both ends of the soil body for electroosmotic drainage and consolidation; the flocculant is 0.3% polyacrylamide by mass of the pre-treated sludge and 1.8‰ chitosan by mass of the pre-treated sludge. By utilizing the charge neutralization and molecular long chain "adsorption bridging" effect of polyacrylamide, the long chain structure is cemented with the soil particles in the sludge to form large aggregates, and the aggregates collide with each other and sink faster under the action of gravity.

[0030] S3, filling the sludge obtained after dewatering in step 2 into an electroosmosis device for electroosmosis treatment, the electroosmosis time is 6-24 hours;

[0031] S4, adding a curing agent to the sludge treated by flocculation electroosmosis to ensure the formation of a stable block structure and reduce the release of harmful substances, and performing a strength test on the formed block structure to ensure the formation of a stable block structure and obtain recyclable sludge. The curing agent is a composite curing agent, and the curing agent includes slag and wood ash, wherein the carbide slag is 13% of the mass of the pre-treated sludge; and the wood ash is 16% of the mass of the pre-treated sludge.

[0032] Example 2

[0033] This embodiment provides a flocculation-electroosmosis-solidification integrated sludge treatment method, comprising:

[0034] S1, collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0035] S2, fill the pre-treated sludge into a mixing barrel, add tap water at a uniform speed and stir with a mixer until the required water content is reached; add flocculant to the mixing barrel, stir evenly, and let it stand for 6 hours; the flocculant is 0.2% polyacrylamide by mass of the pre-treated sludge and 2‰ chitosan by mass of the pre-treated sludge. By utilizing the charge neutralization of polyacrylamide and the "adsorption bridging" effect of the long molecular chain, the long chain structure is cemented with the soil particles in the sludge to form large aggregates, and the aggregates collide with each other and sink faster under the action of gravity.

[0036] S3, filling the sludge obtained after dewatering in step 2 into an electroosmosis device for electroosmosis treatment, the electroosmosis time is 6-24 hours;

[0037] S4, adding a curing agent to the sludge treated by flocculation electroosmosis to ensure the formation of a stable block structure and reduce the release of harmful substances, and performing a strength test on the formed block structure to ensure the formation of a stable block structure and obtain recyclable sludge. The curing agent is a composite curing agent, and the curing agent includes slag and plant ash, wherein the carbide slag is 10% of the mass of the pre-treated sludge; and the plant ash is 18% of the mass of the pre-treated sludge.

[0038] Example 3

[0039] This embodiment provides a flocculation-electroosmosis-solidification integrated sludge treatment method, comprising:

[0040] S1, collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0041] S2, fill the pre-treated sludge into a mixing barrel, add tap water at a uniform speed in batches while stirring with a mixer until the required water content is reached; add flocculant to the mixing barrel, stir evenly, and let stand for 6 hours; the flocculant is 0.35% polyacrylamide by mass of the pre-treated sludge and 1‰ chitosan by mass of the pre-treated sludge. By utilizing the charge neutralization of polyacrylamide and the "adsorption bridging" effect of the long molecular chain, the long chain structure is cemented with the soil particles in the sludge to form large aggregates, and the aggregates collide with each other and sink faster under the action of gravity.

[0042] S3, filling the sludge obtained after dewatering in step 2 into an electroosmosis device for electroosmosis treatment, the electroosmosis time is 6-24 hours;

[0043] S4, adding a curing agent to the sludge treated by flocculation electroosmosis to ensure the formation of a stable block structure and reduce the release of harmful substances, and performing a strength test on the formed block structure to ensure the formation of a stable block structure and obtain recyclable sludge. The curing agent is a composite curing agent, and the curing agent includes slag and plant ash, wherein the carbide slag is 15% of the mass of the pre-treated sludge; and the plant ash is 15% of the mass of the pre-treated sludge.

[0044] Example 4

[0045] This embodiment provides a flocculation-electroosmosis-solidification integrated sludge treatment method, comprising:

[0046] S1, collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0047] S2, fill the pre-treated sludge into a mixing barrel, add tap water at a uniform speed in batches while stirring with a mixer until the required water content is reached; add flocculant to the mixing barrel, stir evenly, and let stand for 6 hours; the flocculant is 0.35% polyacrylamide by mass of the pre-treated sludge and 1‰ chitosan by mass of the pre-treated sludge. By utilizing the charge neutralization of polyacrylamide and the "adsorption bridging" effect of the long molecular chain, the long chain structure is cemented with the soil particles in the sludge to form large aggregates, and the aggregates collide with each other and sink faster under the action of gravity.

[0048] S3, filling the sludge obtained after dewatering in step 2 into an electroosmosis device for electroosmosis treatment, the electroosmosis time is 6-24 hours;

[0049] S4, adding a curing agent to the sludge treated by flocculation electroosmosis to ensure the formation of a stable block structure and reduce the release of harmful substances, and performing a strength test on the formed block structure to ensure the formation of a stable block structure and obtain recyclable sludge. The curing agent is a composite curing agent, and the curing agent includes slag and plant ash, wherein the carbide slag is 10% of the mass of the pre-treated sludge; and the plant ash is 15% of the mass of the pre-treated sludge.

[0050] Example 5

[0051] This embodiment provides a flocculation-electroosmosis-solidification integrated sludge treatment method, comprising:

[0052] S1, collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0053] S2, fill the pre-treated sludge into a mixing barrel, add tap water at a uniform speed in batches while stirring with a mixer until the required water content is reached; add flocculant to the mixing barrel, stir evenly, and let stand for 6 hours; the flocculant is 0.35% polyacrylamide by mass of the pre-treated sludge and 1‰ chitosan by mass of the pre-treated sludge. By utilizing the charge neutralization of polyacrylamide and the "adsorption bridging" effect of the long molecular chain, the long chain structure is cemented with the soil particles in the sludge to form large aggregates, and the aggregates collide with each other and sink faster under the action of gravity.

[0054] S3, filling the sludge obtained after dewatering in step 2 into an electroosmosis device for electroosmosis treatment, the electroosmosis time is 6-24 hours;

[0055] S4, adding a curing agent to the sludge treated by flocculation electroosmosis to ensure the formation of a stable block structure and reduce the release of harmful substances, and performing a strength test on the formed block structure to ensure the formation of a stable block structure and obtain recyclable sludge. The curing agent is a composite curing agent, and the curing agent includes slag and plant ash, wherein the carbide slag is 15% of the mass of the pre-treated sludge; and the plant ash is 18% of the mass of the pre-treated sludge.

[0056] Comparative Example 1

[0057] This comparative example comprises the following steps:

[0058] (1) collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0059] (2) The pre-treated sludge is filled into a mixing barrel, and tap water is added at a uniform speed in batches while stirring with a mixer until the required water content is reached; flocculants are added into the mixing barrel, stirred evenly, and left to stand for 6 hours; the flocculants are 0.3% polyacrylamide and 1.8‰ chitosan per the mass of the pre-treated sludge. By utilizing the charge neutralization of polyacrylamide and the "adsorption bridging" effect of the long molecular chain, the long chain structure is cemented with the soil particles in the sludge to form large aggregates, which collide with each other and sink faster under the action of gravity.

[0060] (3) The sludge obtained after the water removal in step 2 is filled into an electroosmosis device for electroosmosis treatment, and the electroosmosis time is 6-24 hours.

[0061] Comparative Example 2

[0062] This comparative example comprises the following steps:

[0063] (1) collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge;

[0064] (2) The pretreated sludge is filled into a mixing barrel, and tap water is added in batches at a uniform speed while stirring with a mixer until the required water content is reached; a curing agent is added into the mixing barrel, stirred evenly, and allowed to stand for 6 hours; the curing agent is a composite curing agent, and the curing agent includes slag and wood ash, wherein the carbide slag accounts for 13% of the mass of the pretreated sludge; and the wood ash accounts for 16% of the mass of the pretreated sludge.

[0065] (3) The sludge obtained after the water removal in step 2 is filled into an electroosmosis device for electroosmosis treatment, and the electroosmosis time is 6-24 hours.

[0066] The treated sludge obtained from Example 1, Comparative Example 1 and Comparative Example 2 was tested, and the test data are shown in Table 1.

[0067] Table 1

[0068] Original sludge moisture content Moisture content of sludge after solidification Original silt shear strength Shear strength of solidified sludge Example 1 100％ 26.78％ 17.2kPa 80.5kPa Comparative Example 1 100％ 60.89％ 17.2kPa 23.4kPa Comparative Example 2 100％ 62.34％ 17.2kPa 22.6kPa

[0069] By comparing the experimental data in the above table, it is found that the combination of flocculation-electroosmosis-solidification can significantly reduce the moisture content of the sludge, significantly increase the shear strength of the sludge, and enable the sludge with high water content to be solidified with better results.

[0070] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0071] It should be noted that the technical features not described in detail in the present invention can be implemented by any existing technology.

Claims

1. A flocculation-electroosmosis-solidification integrated sludge treatment method, characterized in that: include: (1) collecting sludge on site, filtering and removing impurities on the surface of the sludge to obtain pretreated sludge; (2) Pour the pretreated sludge into a mixing barrel, add tap water at a constant speed in batches while stirring with a mixer until the required water content is reached; add flocculant into the mixing barrel, stir evenly, and let stand for 6 hours; (3) filling the sludge obtained after dewatering in step 2 into an electroosmosis device for electroosmosis treatment, the electroosmosis time being 6-24 hours; (4) A curing agent is added to the sludge treated by flocculation and electroosmosis, and a strength test is performed on the formed block structure to ensure that a stable block structure is formed to obtain recyclable sludge.

2. A flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 1, characterized in that: The flocculants include polyacrylamide and chitosan.

3. A flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 2, characterized in that: The polyacrylamide accounts for 0.2% to 0.35% of the mass of the pre-treated sludge; and the chitosan accounts for 1‰ to 2‰ of the mass of the pre-treated sludge.

4. The flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 1, characterized in that: The curing agent is a composite curing agent.

5. The flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 4, characterized in that: The curing agent includes carbide slag and wood ash.

6. A flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 5, characterized in that: The carbide slag accounts for 10% to 15% of the mass of the pre-treated sludge; and the plant ash accounts for 15% to 18% of the mass of the pre-treated sludge.

7. The flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 1, characterized in that: The electroosmosis device includes a soil sample tank, a water collection tank, an electrode plate and a DC power supply. The electrode plate includes an anode plate and a cathode plate arranged on both sides of the soil sample tank. The anode plate and the cathode plate are respectively connected to the DC power supply through wires. The electroosmosis treatment refers to turning on the DC power supply to make the water in the solidified sludge flow from the anode to the cathode and be discharged.

8. The flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 7, characterized in that: When the soil sample tank is an indoor model box, a GW GPS3303c DC power supply with a limit value of 30V and 3A and a cross-sectional area of ​​1mm 2 of copper wire.

9. The flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 7, characterized in that: When the soil sample tank is an outdoor open space, a DC power supply with a limit of 240V and 1A and a cross-sectional area of ​​5mm 2 of copper wire.

10. The flocculation-electroosmosis-solidification integrated sludge treatment method according to claim 7, characterized in that: The electrode plate is made of an iron electrode plate or a copper electrode plate with a size of 100 mm×100 mm.

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