A method for solidifying Yellow River sediment using sand washing wastewater

Abstract

The present invention discloses a method for solidifying Yellow River sediment using sand washing wastewater. The method comprises: (1) adding cadherin, sodium gluconate, urea, and carbonate mineralized bacteria to the sand washing wastewater and stirring evenly to obtain liquid A; (2) uniformly mixing Yellow River sediment, phosphoric acid, calcium hydrogen sulfate, and activated silica fiber, standing for 8 to 12 hours, adding calcium hydroxide to neutralize the pH to 6 to 8, and mixing evenly again to obtain mixture B; (3) adding the above liquid A and mixture B to a blender, adding low modulus sodium silicate, stirring evenly, and forming to obtain solidified Yellow River sediment. The present invention not only realizes the resource utilization of sand washing wastewater and avoids its pollution to groundwater and soil; but also achieves a good solidification effect of Yellow River sediment and long-term stability of the solidification effect through the organic bonding, inorganic solidification, and microbial reinforcement of different component materials.

Description

Technical Field

[0001] The present invention relates to the technical field of sediment solidification, and more precisely, to a method for solidifying Yellow River sediment by utilizing sand washing wastewater. Background Art

[0002] Yellow River sediment primarily originates from Quaternary sediments deposited on the Loess Plateau. Rainfall from the Loess Plateau scours and deposits it into the Yellow River's tributaries and main channel, resulting in a relatively uniform composition and properties. While inherently harmless, Yellow River sediment, deposited within the Yellow River channel from the Loess Plateau, can cause river uplift due to its accumulation, posing a significant safety hazard to residents downstream. Therefore, its removal and utilization remain a crucial issue surrounding the Yellow River. Currently, the main methods for utilizing and consolidating Yellow River sediment are: ① Consolidation and reinforcement using cement and other cementitious materials combined with other mechanical, physical, and chemical stimulation methods; ② Sand solidification through the polymerization of organic compounds such as calcium polyacrylate and acrylamide; and ③ Sand solidification through microbial mineralization and sedimentation. However, all of the above methods have certain drawbacks. Solidification using cement and other cementitious materials is not only costly but also causes secondary pollution to the sediment. Furthermore, the solidified sand lacks strength and has poor water resistance. Solidification using organic polymerization also has poor water resistance and low solidification strength. Solidification using microorganisms not only has low strength and a long time, but also produces uneven solidification results, resulting in poor water resistance and low strength. Therefore, it is particularly important to research solidification methods that can achieve rapid solidification of Yellow River sediment, have good durability, and not cause secondary pollution to the environment.

[0003] In the construction industry, sand and gravel contain a lot of impurities and dust. To prevent the impact of sand and gravel impurities on the performance of concrete, the sand and gravel excavated from the mining area needs to be cleaned. The flocculant used for cleaning is generally polyacrylamide. However, due to the significant adverse effects of polyacrylamide on the performance of concrete, the wastewater after cleaning can only be discharged, but this will cause pollution to the soil and the environment. Therefore, the comprehensive utilization of sand washing wastewater is also crucial. At the same time, the polyacrylamide contained in sand washing wastewater has a certain consolidation ability and can absorb soil, which provides the possibility of its use in soil consolidation. However, there is currently no relevant research in this area. Summary of the Invention

[0004] To address the challenges presented by the prior art, the present invention proposes a method for solidifying Yellow River sediment using sand-washing wastewater. This method utilizes the wastewater as a resource, preventing groundwater and soil contamination, while also improving the effectiveness, mechanical properties, and water resistance of the solidified sediment.

[0005] The present invention provides a method for solidifying Yellow River sediment using sand washing wastewater, comprising the following steps:

[0006] (1) Adding cadherin, sodium gluconate, urea, and carbonate mineralized bacteria to sand washing wastewater and stirring uniformly to obtain liquid A;

[0007] (2) Yellow River sediment, phosphoric acid, calcium hydrogen sulfate, and activated silica fiber were mixed uniformly, allowed to stand for 8 to 12 hours, and then calcium hydroxide was added to neutralize the pH to 6 to 8, and the mixture was mixed again to obtain a mixture B;

[0008] (3) adding the above liquid A and mixture B into a blender, adding low modulus sodium silicate, stirring evenly and shaping to obtain solidified Yellow River sediment;

[0009] The mass fractions of the above-mentioned raw materials are as follows:

[0010] 35-50 parts of sand washing wastewater,

[0011] 3-6 copies of E-cadherin,

[0012] 5-10 parts of sodium gluconate,

[0013] 1 to 6 parts of urea,

[0014] 0.01-0.5 parts of carbonate mineralized bacteria,

[0015] 100 parts of Yellow River silt,

[0016] 1-3 parts of phosphoric acid,

[0017] 2-4 parts of calcium hydrogen sulfate,

[0018] 2-5 parts of active silica fiber,

[0019] 5-10 parts of low modulus sodium silicate;

[0020] The sand washing wastewater is the wastewater obtained by washing construction sand with an aqueous solution containing polyacrylamide flocculant.

[0021] When the cadherin of the present invention is a liquid, the water content thereof should be considered and included in the total water content of liquid A.

[0022] When the sodium gluconate of the present invention is a solution, the water content thereof should be considered and included in the water content of liquid A.

[0023] The carbonate mineralizing bacteria of the present invention are bacteria that can deposit and mineralize calcium ions in the form of calcium carbonate, including natural bacteria and anaerobic bacteria that have been artificially genetically modified to have this ability.

[0024] The modulus of the low modulus sodium silicate of the present invention is not higher than 2.4.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] Sand washing wastewater contains polyacrylamide and mud, which is an industrial wastewater. Random discharge pollutes soil and groundwater resources. The present invention utilizes polyacrylamide in sand washing wastewater in combination with cadherin to achieve good early consolidation of Yellow River silt. After acidification and modification, the Yellow River silt increases its activity and can react with the mixture to improve the strength of the mixture. While playing a good fiber role, the active silica fiber can participate in the hydration reaction of Yellow River silt and calcareous materials because of its high activity, thereby improving the bonding between them. However, after the Yellow River silt is activated, only a small part of it is active, and most of it cannot participate in the solidification reaction. Therefore, in order to further improve the solidification effect of the silt, on the basis of the above reaction, calcium carbonate mineralizing bacteria are added. Further, through the mineralization deposition of calcium carbonate mineralizing bacteria, the density of the solidified body and the bonding strength between the particles are improved, thereby improving the durability of the solidification. Low modulus sodium silicate slowly dissolves in the slurry and bonds with the active silica fiber and the large amount of silica in the Yellow River silt to form a network structure, thereby improving the overall consolidation effect.

[0027] The present invention not only realizes the resource utilization of sand washing wastewater and avoids its pollution to groundwater and soil; but also can achieve good solidification effect and long-term stability of the Yellow River sediment through the organic bonding, inorganic solidification and microbial reinforcement of different component materials. Specific embodiments

[0028] The technical solution of the present invention will now be further described with reference to embodiments, but is not limited to the following implementation scenarios.

[0029] The amounts of the components in the following examples are in parts by mass.

[0030] Example 1

[0031] A method for solidifying Yellow River sediment using sand washing wastewater comprises the following steps:

[0032] (1) Add 6 parts of cadherin, 5 parts of sodium gluconate, 6 parts of urea, and 0.01 parts of carbonate mineralized bacteria to 35 parts of sand washing wastewater, and stir evenly to obtain liquid A;

[0033] (2) 100 parts of Yellow River sediment, 3 parts of phosphoric acid, 2 parts of calcium hydrogen sulfate, and 5 parts of activated silica fiber were mixed evenly, allowed to stand for 8 hours, and then calcium hydroxide was added to neutralize the pH to 8. The mixture was mixed evenly again to obtain a mixture B;

[0034] (3) Add the above liquid A and mixture B into a blender, and add 5 parts of sodium silicate with a modulus of 2.4, stir evenly and shape, and cure to the corresponding age to obtain solidified Yellow River sediment.

[0035] Example 2

[0036] A method for solidifying Yellow River sediment using sand washing wastewater comprises the following steps:

[0037] (1) Add 3 parts of cadherin, 10 parts of sodium gluconate, 1 part of urea, and 0.5 parts of carbonate mineralized bacteria to 50 parts of sand washing wastewater, and stir evenly to obtain liquid A;

[0038] (2) 100 parts of Yellow River sediment, 1 part of phosphoric acid, 4 parts of calcium hydrogen sulfate, and 2 parts of activated silica fiber were mixed uniformly, allowed to stand for 12 hours, and then calcium hydroxide was added to neutralize the pH to 6. The mixture was mixed uniformly again to obtain a mixture B;

[0039] (3) Add the above liquid A and mixture B into a blender, and add 10 parts of sodium silicate with a modulus of 2.0, stir evenly and shape, and cure to the corresponding age to obtain solidified Yellow River sediment.

[0040] Example 3

[0041] A method for solidifying Yellow River sediment using sand washing wastewater comprises the following steps:

[0042] (1) Add 4 parts of cadherin, 8 parts of sodium gluconate, 4 parts of urea, and 0.2 parts of carbonate mineralized bacteria to 40 parts of sand washing wastewater, and stir evenly to obtain liquid A;

[0043] (2) 100 parts of Yellow River sediment, 2 parts of phosphoric acid, 3 parts of calcium hydrogen sulfate, and 4 parts of activated silica fiber were mixed evenly, allowed to stand for 10 hours, and then calcium hydroxide was added to neutralize the pH to 7. The mixture was mixed evenly again to obtain a mixture B;

[0044] (3) Add the above liquid A and mixture B into a blender, and add 8 parts of sodium silicate with a modulus of 2.2, stir evenly and shape, and cure to the corresponding age to obtain solidified Yellow River sediment.

[0045] Control group 1

[0046] The E-cadherin in Example 3 was removed, and the rest remained unchanged.

[0047] Control group 2

[0048] 100 parts of Yellow River silt were added with 40 parts of sand washing wastewater, stirred evenly to form a solidified silt, and cured for 28 days to obtain solidified Yellow River silt.

[0049] Control group 3

[0050] Add 40 parts of tap water to 100 parts of Yellow River silt, stir evenly to form it, and cure it for 28 days to obtain solidified Yellow River silt.

[0051] Control group 4

[0052] The sand washing wastewater in Example 3 was changed to tap water, and the rest remained unchanged.

[0053] Control group 5

[0054] Add 10 parts of cement soil solidifier to 100 parts of Yellow River silt, add 40 parts of water, stir evenly to form, and cure for 60 days to obtain solidified Yellow River silt.

[0055] Control group 6

[0056] Add 2 parts of organic solidifying agent to 100 parts of Yellow River silt, add 40 parts of water, stir evenly to form, and cure for 60 days to obtain solidified Yellow River silt.

[0057] Control group 7

[0058] Add 0.2 parts of calcium carbonate mineralization powder to 100 parts of Yellow River silt, add 30 parts of water, stir evenly to form, and cure for 60 days to obtain solidified Yellow River silt.

[0059] The properties of the solidified Yellow River silt prepared in the above embodiments, the comparative example, and the unsolidified original Yellow River silt were analyzed. 100 mm × 100 mm × 100 mm test blocks of the solidified Yellow River silt and the unsolidified Yellow River silt were prepared and placed in still water and submerged, and then subjected to a disintegration test. The performance indicators are shown in Table 1:

[0060] Table 1 Yellow River sediment solidification effect

[0061]

[0062] From the comparison of permeability coefficients in Table 1, it can be seen that compared with the control group, the present invention has a significant improvement in the anti-seepage performance of Yellow River sediment, and the anti-seepage performance will further improve with the extension of curing time. The comparison of compressive strength also shows that the curing method of the present invention has a significant effect on improving the compressive strength of Yellow River sediment. In summary, the curing method of the present invention can achieve a good curing effect on Yellow River sediment. Compared with control group 4, it can be seen that the anti-seepage performance and compressive strength of Example 3 are significantly higher, which shows that sand washing wastewater can improve the consolidation effect of sediment. Control groups 5 to 7 are the curing effects of cement curing agents, organic curing agents, and microbial curing agents available on the market or under research. As can be seen from the permeability coefficient and compressive strength, the curing effect of the present invention is better.

Claims

1. A method for solidifying Yellow River sediment using sand washing wastewater, characterized in that: The following steps are involved: (1) Add cadherin, sodium gluconate, urea and carbonate mineralized bacteria to sand washing wastewater and stir evenly to obtain liquid A; (2) Yellow River sediment, phosphoric acid, calcium hydrogen sulfate, and activated silica fiber were mixed evenly, allowed to stand for 8-12 hours, and then calcium hydroxide was added to neutralize the pH to 6-8. The mixture was then mixed evenly again to obtain mixture B. (3) Add the above liquid A and mixture B into a mixer, add low modulus sodium silicate, stir evenly and shape to obtain solidified Yellow River sediment; The mass fractions of each component raw material are as follows: 35~50 parts of sand washing wastewater, 3~6 copies of E-cadherin, 5-10 parts of sodium gluconate, 1~6 parts of urea, 0.01~0.5 parts of carbonate mineralized bacteria, 100 parts of Yellow River silt, 1~3 parts of phosphoric acid, 2~4 parts of calcium hydrogen sulfate, 2~5 parts of active silica fiber, 5-10 parts of low modulus sodium silicate; The sand washing wastewater is the wastewater obtained by washing construction sand with an aqueous solution containing polyacrylamide flocculant.

2. The method for solidifying Yellow River sediment using sand washing wastewater according to claim 1, characterized in that: The modulus of the low modulus sodium silicate is not higher than 2.4.

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