A sludge treatment method for reducing the spread of sludge pollutants

Abstract

The present invention provides a sludge treatment method for reducing the diffusion of sludge pollutants, comprising the following steps: step S1, preparing underwater non-dispersible mud, and laying 80-150 cm thick underwater non-dispersible mud on the surface of the sludge soft foundation; step S2, preparing sludge solidifying agent slurry, and conveying the sludge solidifying agent slurry to the mixing head spraying port of the in-situ mixing equipment; before the initial setting of the underwater non-dispersible lightweight mud, the sludge is stirred in-situ, and the sludge solidifying agent slurry is sprayed to solidify the sludge in-situ. With the technical solution of the present invention, the solidifying agent is stirred with the sludge to form an underwater anti-dispersion solidified body, and the sludge can be solidified in-situ; while improving the properties of the sludge, the pollutants in the sludge are blocked from diffusing into the water, and the sludge can be harmlessly treated. Secondly, the waste slag and sludge are harmlessly treated and resourced, the disposal cost of waste is saved, and energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and in particular to a sludge treatment method for reducing the diffusion of sludge pollutants. Background Art

[0002] Every year, a large amount of silt is produced in my country during the construction and maintenance of ports and waterways, as well as the management of water environments such as rivers and lakes. Silt has a high water content, a high clay content, and a complex composition. It not only includes mineral components, but also contains organic matter, heavy metals and other components, which will pollute the natural environment. Therefore, it is necessary to harmlessly treat the silt and utilize it as a resource. At present, the soft foundation treatment technologies for silt at home and abroad mainly include dehydration and drying method, vacuum preloading soft foundation reinforcement method and chemical solidification treatment.

[0003] Traditional curing agents and construction methods require mechanical stirring during the treatment of sludge. At this time, the sludge and its pollutants will spread around. At the same time, the formed sludge solid body has weak resistance to water erosion, and harmful substances such as heavy metals will spread around, affecting the environment.

[0004] The dehydration and drying method uses mechanical equipment to extract the sludge, and after a series of treatments such as flocculation, sedimentation and dehydration, it is recycled or landfilled. In this process, a larger area is required to stack and dispose of the sludge, and secondary pollution to the natural environment may be caused during transportation and landfill.

[0005] The vacuum preloading soft foundation reinforcement method is to lay a sand cushion layer of a certain thickness on the silt surface, lay a sealing membrane on the sand cushion layer, and set up a horizontal and vertical drainage system in the sand cushion layer. By evacuating the system, a pressure difference is formed between the drainage system and the surrounding soil, thereby achieving the purpose of reinforcing the soft foundation. However, this method has problems such as long construction period and low foundation bearing capacity after foundation precipitation.

[0006] The chemical solidification method is to mix the chemical solidifier with the sludge and then transport it for paving or loading for consolidation. During the in-situ solidification process, due to the stirring of mechanical equipment, pollutants in the sludge may be diffused, causing harm to the environment. Summary of the invention

[0007] In view of the above technical problems, the present invention discloses a sludge treatment method for reducing the diffusion of sludge pollutants, performing in-situ solidification treatment on the sludge, solving the problem of pollutant diffusion during mechanical stirring of sludge and a solidifying agent, and at the same time being able to render the sludge harmless.

[0008] To this end, the technical solution adopted by the present invention is:

[0009] A sludge treatment method for reducing the diffusion of sludge pollutants comprises the following steps:

[0010] Step S1, preparing underwater non-dispersible mud, and laying 80-150 cm thick underwater non-dispersible mud on the surface of the silt soft foundation;

[0011] Step S2, prepare sludge curing agent slurry, convey the sludge curing agent slurry to the spray port of the mixing head of the in-situ mixing equipment; before the underwater non-dispersible light mud initially sets, stir the sludge in-situ, and spray the sludge curing agent slurry to solidify the sludge in-situ. Wherein, the sludge curing agent slurry is obtained by mixing a curing agent and water. The underwater non-dispersible mud is mud that will not disperse in water, and the components of the prior art can be used. People may slightly change the name of the mud, such as underwater non-dispersible grouting material, underwater non-dispersible cement slurry, etc. Furthermore, according to the actual engineering needs, a retarder can be added to the underwater non-dispersible light mud to extend its initial setting time and meet the construction time requirements.

[0012] This technical solution is adopted by covering the underwater non-dispersible mud on the surface of the underwater silt soft base, and then injecting curing agent slurry for stirring so that it and the silt are solidified in situ, thus solving the problem of pollutant diffusion in the process of direct mechanical stirring of silt and curing agent, which is more environmentally friendly.

[0013] As a further improvement of the present invention, in step S2, a direct-insertion stirring device is used to stir the sludge in situ.

[0014] As a further improvement of the present invention, in step S2, the stirring device runs in a forward direction, the stirring head is slowly lowered, and the curing agent slurry is sprayed.

[0015] As a further improvement of the present invention, the components and their mass fractions contained in the underwater non-dispersible mud are: 1000 parts of waste mud, 50-100 parts of geopolymer-based curing agent, 0.35-0.75 parts of polyacrylamide, 1-2 parts of sodium hydroxymethyl cellulose, and 0.2-0.5 parts of polycarboxylic acid water reducer.

[0016] As a further improvement of the present invention, the water content of the waste sludge is 90-120wt%.

[0017] As a further improvement of the present invention, the geopolymer-based curing agent is a mixture of water glass, silicate cement and waste slag, and the mass ratio of the water glass, silicate cement and slag is 1:1-2:2-3.

[0018] As a further improvement of the present invention, the mass ratio of water glass, silicate cement and slag is 20:32:48.

[0019] As a further improvement of the present invention, the preparation step of the underwater non-dispersible mud includes: weighing various raw materials, adding the various raw materials into a mixer and mixing them evenly, so as to obtain the underwater non-dispersible mud.

[0020] As a further improvement of the present invention, the sludge solidifying agent slurry is prepared by mixing a solidifying agent with water, and the solidifying agent comprises the following components and their mass fractions: 10 to 30 parts of geopolymer-based solidifying agent, 15 to 30 parts of ferrous sulfate, 15 to 25 parts of zeolite, 4 to 10 parts of sodium polyacrylate, 1 to 2 parts of anti-dispersion agent, and 0.5 to 1 part of polycarboxylic acid water reducer.

[0021] As a further improvement of the present invention, step S1 also includes: sampling the sludge and measuring its relevant properties and pollutant content, and the curing agent in step S2 is a ratio of corresponding components determined according to the measured relevant properties and pollutant content of the sludge.

[0022] With this technical solution, different agents can be added to the curing agent to preliminarily treat the pollutants and reduce their pollution, depending on the types of pollutants in the sludge. At the same time, according to the properties of the sludge (such as water content, sludge specific resistance, pH value, etc.), the dosage of the geopolymer-based curing agent and other components is adjusted, so that the solidified sludge has different mechanical properties to meet different engineering needs.

[0023] As a further improvement of the present invention, the anti-dispersant is a mixture of polyacrylamide, precipitated silica solution and starch industrial waste solution, and the mass ratio of the polyacrylamide, precipitated silica solution and starch industrial waste solution is 3-5:1:1-2. Further, the mass ratio of the polyacrylamide, precipitated silica solution and starch industrial waste solution is 11:3:6. Further, the mass concentration of the precipitated silica solution is 15-25%, and the mass concentration of the starch industrial waste solution is 25%-35%. Further, the mass concentration of the precipitated silica solution is 20%, and the mass concentration of the starch industrial waste solution is 32%.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] By adopting the technical solution of the present invention, the curing agent and the sludge are stirred to form an underwater anti-dispersion solidified body, and the sludge can be solidified in situ; while improving the properties of the sludge, the pollutants in the sludge are blocked from diffusing into the water, solving the problem of sludge polluting the natural environment, and the problem of pollutant diffusion during the mechanical stirring of sludge and curing agent in the prior art, and at the same time, the sludge can be harmlessly treated. Secondly, the underwater non-dispersible mud used in this method is prepared from engineering waste, which realizes the harmless and resourceful treatment of waste slag and sludge, saves the cost of waste disposal, and achieves energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of a sludge treatment device according to an embodiment of the present invention.

[0027] 1- silt, 2- underwater non-dispersible mud, 3- mud pump, 4- mixing head spray nozzle, 5- direct plug-in mixing equipment. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described in further detail below.

[0029] A sludge treatment method for reducing the spread of sludge pollutants, the device is as follows Figure 1 As shown, it includes the following steps:

[0030] (1) Sampling sludge and determining its relevant properties and pollutant content;

[0031] (2) laying 80 to 150 cm thick underwater non-dispersible mud 2 on the soft foundation surface of the silt 1;

[0032] (3) According to the properties of the sludge in the construction area, the corresponding chemical curing agent mix ratio is designed, and the sludge is sent to the slurry mixer through a screw conveyor and mixed with water to form a curing agent slurry; specifically, the mix ratio of the corresponding chemical curing agent can be adjusted according to the water content, organic matter and pollutant types and contents of the sludge.

[0033] (4) using a mud pump 3 to transport the curing agent slurry to the mixing head spray port 4 of the in-situ mixing equipment;

[0034] (5) Before the initial setting of the underwater non-dispersible lightweight mud, the sludge is stirred in situ using a direct plug-in stirring device 5. The stirring device is rotated forward to slowly lower the stirring head and spray the curing agent slurry until the curing design elevation is reached;

[0035] The underwater non-dispersible mud is composed of the following raw materials according to weight components: 1000 parts of waste mud, 50-100 parts of geopolymer-based curing agent, 0.35-0.75 parts of polyacrylamide, 1-2 parts of sodium hydroxymethyl cellulose, and 0.2-0.5 parts of polycarboxylic acid water reducer; the water content of the waste mud is 90-120wt%; the geopolymer-based curing agent includes a mixture of water glass, silicate cement and waste slag, and the proportion of the water glass, silicate cement and slag components is 20:32:48; the preparation steps of the underwater non-dispersible mud are as follows: weigh each raw material, add each raw material into a mixer and mix evenly to obtain the underwater non-dispersible mud.

[0036] The chemical curing agent is composed of the following raw materials according to weight components: 10-30 parts of polymer-based curing agent, 15-30 parts of ferrous sulfate, 15-25 parts of zeolite, 4-10 parts of sodium polyacrylate, 1-2 parts of anti-dispersion agent, and 0.5-1 part of polycarboxylic acid water reducer; the anti-dispersion agent includes polyacrylamide, precipitated silica solution and starch industrial waste solution, and the ratio of each component of the polyacrylamide precipitated silica solution and the starch industrial waste solution is 11:3:6; the mass concentration of the precipitated silica solution is 20%, and the mass concentration of the starch industrial waste solution is 32%.

[0037] After the sludge is treated by the treatment method of this embodiment, the pollutants in the sludge are prevented from spreading, and the waste debris and sludge are treated harmlessly and recycled.

[0038] Example 1

[0039] Silt sample 1, water content is 90%.

[0040] The sludge sample 1 is processed, comprising the following steps:

[0041] Step 1: Preparation of underwater non-dispersible mud:

[0042] The underwater non-dispersible mud is composed of the following raw materials according to weight components: 1000 parts of waste mud, 80 parts of geopolymer-based curing agent, 0.75 parts of polyacrylamide, 1 part of sodium hydroxymethyl cellulose, and 0.2-0.5 parts of polycarboxylic acid water reducer; the water content of the waste mud is 120wt%; the geopolymer-based curing agent includes a mixture of water glass, silicate cement and waste slag, and the proportions of the water glass, silicate cement and slag are 20:32:48; the preparation steps of the underwater non-dispersible mud are as follows: weigh each raw material, add each raw material into a mixer and mix evenly to obtain the underwater non-dispersible mud.

[0043] Step 2: Spread the underwater non-dispersible mud to the sludge surface with a height of 150 cm.

[0044] Step 3: Before the initial setting of the underwater non-dispersible mud, mix the chemical curing agent with the sludge:

[0045] The chemical curing agent is composed of the following raw materials according to weight components: 30 parts of geopolymer-based curing agent, 20 parts of ferrous sulfate, 25 parts of zeolite, 10 parts of sodium polyacrylate, 2 parts of anti-dispersant, and 0.5 parts of polycarboxylic acid water reducer; the anti-dispersant includes polyacrylamide, precipitated silica solution and starch industrial waste solution, and the ratio of the components of the polyacrylamide precipitated silica solution and the starch industrial waste solution is 11:3:6; the mass concentration of the precipitated silica solution is 20%, and the mass concentration of the starch industrial waste solution is 32%.

[0046] Example 2

[0047] Silt sample 2, water content is 74%.

[0048] The sludge sample 2 is processed, comprising the following steps:

[0049] Step 1: Preparation of underwater non-dispersible mud:

[0050] The underwater non-dispersible mud is composed of the following raw materials according to weight components: 1000 parts of waste mud, 80 parts of geopolymer-based curing agent, 0.75 parts of polyacrylamide, 1 part of sodium hydroxymethyl cellulose, and 0.2-0.5 parts of polycarboxylic acid water reducer; the water content of the waste mud is 120wt%; the geopolymer-based curing agent includes a mixture of water glass, silicate cement and waste slag, and the proportions of the water glass, silicate cement and slag are 20:32:48; the preparation steps of the underwater non-dispersible mud are as follows: weigh each raw material, add each raw material into a mixer and mix evenly to obtain the underwater non-dispersible mud.

[0051] Step 2: Spread the underwater non-dispersible mud to the sludge surface with a height of 150 cm.

[0052] Step 3: Before the initial setting of the underwater non-dispersible mud, mix the chemical curing agent with the sludge:

[0053] The chemical curing agent is composed of the following raw materials according to weight components: 20 parts of geopolymer-based curing agent, 20 parts of ferrous sulfate, 25 parts of zeolite, 7 parts of sodium polyacrylate, 1 part of anti-dispersant, and 1 part of polycarboxylic acid water reducer; the anti-dispersant includes polyacrylamide, precipitated silica solution and starch industrial waste solution, and the ratio of the components of the polyacrylamide precipitated silica solution and the starch industrial waste solution is 11:3:6; the mass concentration of the precipitated silica solution is 20%, and the mass concentration of the starch industrial waste solution is 32%.

[0054] Comparative Example 1

[0055] The sludge sample 1 was treated using traditional construction methods, including:

[0056] Step 1: Mix and stir the chemical curing agent raw materials evenly;

[0057] Step 2: Stirring the mixed chemical curing agent and sludge in situ;

[0058] Step 3: Turn over and stir the sludge after preliminary stirring.

[0059] Comparative Example 2

[0060] Based on Comparative Example 1, sludge sample 2 was processed.

[0061] The sludge samples 1 and 2 were solidified in situ by using the traditional construction method and the construction method of the embodiment, and then the upper water after the construction was completed was sampled and tested for pollutant content. The test results are shown in Table 1:

[0062] Table 1 Pollutant content before and after treatment of the embodiments and comparative examples (heavy metal content in mg / kg)

[0063] Types of heavy metals Sludge sample 1 Sludge sample 2 Comparative Example 1 Comparative Example 2 Example 1 Example 2 Standard value Mercury (Hg) 0.012-2.9 0.01-1.7 0.01 0.05 <0.001 <0.001 0.001 Lead (Pb) 1.66-32 4.3-51.23 0.08 0.13 <0.01 <0.01 0.1 Arsenic (As) 0.6-56 0.9-14.3 0.14 <0.07 <0.07 <0.07 0.1 Cadmium (Cd) 0.03-14.4 0.23-4.03 0.04 <0.01 <0.01 <0.01 0.01 Copper (Cu) 1.26-106 0.8-12.79 0.26 0.03 <0.1 <0.1 1 Zinc (Zn) 2.05-303 1.94-202.29 0.75 0.5 <0.1 <0.1 2 Chromium (Cr) 0.78-76 0.73-68.26 0.19 0.17 <0.05 <0.05 0.1

[0064] It can be seen from the test data that in the traditional in-situ solidification construction method, the contents of mercury, arsenic, cadmium and chromium detected in the upper water sample of Example 1 exceeded the standard; the contents of mercury, lead and chromium detected in the upper water sample of Example 2 exceeded the standard; while the contents of heavy metal elements detected in the in-situ solidification of sludge using the construction method of the embodiment did not exceed the standard, and the heavy metal element content was low, which can effectively prevent heavy metals from diffusing to the surroundings and polluting the environment during the in-situ solidification construction of the sludge.

[0065] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A sludge treatment method for reducing the spread of sludge pollutants, characterized in that: The steps include: Step S1, preparing underwater non-dispersible mud, and laying 80-150 cm thick underwater non-dispersible mud on the surface of the silt soft foundation; Step S2, preparing sludge solidifying agent slurry, and conveying the sludge solidifying agent slurry to the spraying port of the mixing head of the in-situ mixing equipment; Before the initial setting of the underwater non-dispersible light mud, the sludge is stirred in situ and the sludge solidifying agent slurry is sprayed to solidify the sludge in situ; The components and their mass fractions of the underwater non-dispersible mud are: 1000 parts of waste mud, 50-100 parts of geopolymer-based curing agent, 0.35-0.75 parts of polyacrylamide, 1-2 parts of sodium hydroxymethyl cellulose, and 0.2-0.5 parts of polycarboxylic acid water reducer.

2. The sludge treatment method for reducing the diffusion of sludge pollutants according to claim 1, characterized in that: In step S2, the sludge is stirred in situ using a direct-insertion stirring device.

3. The sludge treatment method for reducing the diffusion of sludge pollutants according to claim 1, characterized in that: The water content of the waste mud is 90-120wt%.

4. The sludge treatment method for reducing the spread of sludge pollutants according to claim 1, characterized in that: The geopolymer-based curing agent is a mixture of water glass, silicate cement and waste slag, and the mass ratio of the water glass, silicate cement and waste slag is 1:1-2:2-3.

5. The sludge treatment method for reducing the spread of sludge pollutants according to claim 4, characterized in that: The mass ratio of water glass, silicate cement and waste slag is 20:32:

48.

6. The sludge treatment method for reducing the diffusion of sludge pollutants according to claim 1, characterized in that: The preparation step of the underwater non-dispersible mud comprises: weighing various raw materials, adding the various raw materials into a mixer and mixing them evenly, so as to obtain the underwater non-dispersible mud.

7. The sludge treatment method for reducing the diffusion of sludge pollutants according to any one of claims 1 to 6, characterized in that: The sludge solidifying agent slurry is prepared by mixing a solidifying agent with water. The solidifying agent comprises the following components and their mass fractions: 10-30 parts of geopolymer-based solidifying agent, 15-30 parts of ferrous sulfate, 15-25 parts of zeolite, 4-10 parts of sodium polyacrylate, 1-2 parts of anti-dispersant, and 0.5-1 part of polycarboxylic acid water reducer.

8. The sludge treatment method for reducing the diffusion of sludge pollutants according to claim 7, characterized in that: Step S1 also includes: sampling the sludge and measuring its relevant properties and pollutant content. The curing agent in step S2 is a ratio of corresponding components determined according to the measured relevant properties and pollutant content of the sludge.

9. The sludge treatment method for reducing the spread of sludge pollutants according to claim 8, characterized in that: The anti-dispersant is a mixture of polyacrylamide, precipitated silica solution and starch industrial waste solution, wherein the mass ratio of the polyacrylamide, precipitated silica solution and starch industrial waste solution is 3-5:1:1-2; the mass concentration of the precipitated silica solution is 15-25%, and the mass concentration of the starch industrial waste solution is 25%-35%.

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