CN116621417A - Method for rapid cleaning and dehydration of dredging sediment - Google Patents

Abstract

The invention relates to the technical field of bottom mud control, in particular to a method for quickly cleaning and dehydrating dredged bottom mud, which includes the steps of: cutting and stirring the river bank bottom mud by a cutter suction pump to form mud, and outputting the mud by pumping force ;Transport the output mud through the pipeline, and add low molecular weight cationic polymer to the first branch of the pipeline near the river bank to perform primary flocculation of the mud; add high molecular weight flocculation through the second branch near the end of the pipeline Secondary flocculation of the mud with the agent; connect the end of the pipe to the geotextile bag, so that the flocs flowing out of the pipe are directly injected into the geotextile bag for sedimentation and filtration, and the filtered water is directly discharged. The invention utilizes the pipeline secondary flocculation technology to significantly increase the particle size of the mud particles, greatly improve the dehydration efficiency and dehydration speed, and at the same time the dehydration liquid meets the requirements of environmental protection; the technology has the advantages of short processing time, low energy consumption and stable water quality of the dehydration liquid.

Description

A method for rapid cleaning and dehydration of dredged sediment

technical field

The invention relates to the technical field of bottom mud treatment, in particular to a method for rapid cleaning and dehydration of dredged bottom mud.

Background technique

Sediment is the ultimate storage place for various pollutants in the water environment, and is an important factor affecting the quality of the water environment. With the rapid development of the global social economy, large quantities of industrial sewage and domestic sewage are discharged, and the overflow discharge of sewage pumping stations leads to the continuous enrichment of pollutants in the sediment, and the pollution of the sediment is becoming more and more serious.

River channel dredging is one of the important measures to prevent and control sediment pollution and river channel management, and is an important part of comprehensive water environment management. A large amount of high water content mud will be produced during the dredging process. These dredged sediments are bulky, have poor settlement performance, and have complex pollution components, which pose serious ecological risks. How to realize the rapid separation of mud and water and reduce the harm of pollutants to the environment is one of the problems that need to be solved urgently in the field of dredging sediment treatment.

At present, the treatment method of dredging bottom sludge is mainly to suck out the bottom sludge through environmental protection cutter suction and transport it to a fixed mud treatment station for post-processing. The mud from dredging needs to be transported through long-distance pipelines, which increases the transportation cost. At the same time, the special mud treatment station has the disadvantages of relatively long processing time, relatively large floor area, and large proportion of equipment investment.

The sedimentation performance of the dredged mud is poor, and it is difficult to achieve mud-water separation under natural conditions. The method of adding chemical filter aids is usually used to improve the mud-water separation effect. When the existing filter aids are used to condition the dredged sediment, the flocs formed by the agents and the mud have a small particle size, which easily blocks the gaps between the filter medium and the filter cake during filtration, resulting in low mechanical dehydration efficiency. In addition, the dehydration liquid is still polluted after the existing chemical treatment, and a special residual water treatment link is required, which greatly increases the cost of treatment and the difficulty of operation.

Therefore, the prior art still needs to be improved and developed.

Contents of the invention

In view of the above deficiencies in the prior art, the purpose of the present invention is to provide a method for rapid cleaning and dehydration of dredged sediment, so as to improve the dehydration efficiency of dredged sediment, shorten the treatment cycle, and improve the quality of residual water.

Technical scheme of the present invention is as follows:

A method for rapid cleaning and dehydration of dredged sediment, comprising the steps of:

Cutting and agitating the river bank bottom mud by cutter suction pump to form mud, and output the mud by pump force;

The output mud is transported through pipelines, and low molecular weight cationic polymers are added to the first branch of the pipeline near the river bank to perform primary flocculation of the mud. The low molecular weight cationic polymers are polyelectrolyte and polysaccharide-betaine cationic polymerization one or more of the

At the position close to the end of the pipeline, a high molecular weight flocculant is added through the second branch to carry out secondary flocculation of the mud, and the high molecular weight flocculant is one of cationic polyacrylamide, anionic polyacrylamide and nonionic polyacrylamide one or more kinds;

Connect the end of the pipe to the geotextile bag, so that the floc flowing out of the pipe is directly injected into the geotextile bag for sedimentation and filtration, and the filtered water is directly discharged.

The method for rapid cleaning and dehydration of dredged sediment, wherein the molecular weight of the low molecular weight cationic polymer is less than 280,000.

The method for rapid cleaning and dehydration of dredged sediment, wherein, the dosage of the low molecular weight cationic polymer is 0.3-1.2g/kg.

The method for rapid cleaning and dehydration of dredged sediment, wherein the molecular weight of the high molecular weight flocculant is greater than 8 million.

The method for rapid cleaning and dehydration of dredged sediment, wherein, the dosage of the high molecular weight flocculant is 0.2-0.8g/kg.

The method for rapid cleaning and dehydration of dredged sediment, wherein the polyelectrolyte is based on dimethyl diallyl ammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acrylamide oxyethylene One or more of the base dimethyl benzyl ammonium chloride is a monomer, a cationic polymer obtained by homopolymerization or copolymerization; the polysaccharide-betaine cationic polymer is based on chitosan or starch The matrix is a polymer obtained through an esterification reaction with at least one of anhydrous betaine and betaine acid salt.

The method for rapid cleaning and dehydration of dredged sediment, wherein, the distance from the first branch to the second branch is set as S ₁ , and the distance from the second branch to the end of the pipeline is set as S ₂ , so The above _S1 and _S2 meet the following conditions:

S ₁ = S _{1 mixing} + S _{1 reaction} , wherein, S _{1 mixing} is the distance of pipeline mud flow within the time of sufficient mixing of low molecular weight cationic polymer and mud, and S _{1 reaction} is the flocculation reaction time of low molecular weight cationic polymer and mud The distance the pipeline mud flows;

S ₂ = S _{2 mixing} + S _{2 reaction} , wherein, S _{2 mixing} is the distance of pipeline mud flow within the time when the high molecular weight flocculant and mud are fully mixed, and S _{2 reaction} is the pipeline mud within the flocculation reaction time of high molecular weight flocculant and mud flow distance.

The method for rapid cleaning and dehydration of dredging bottom mud, wherein the time required for the mud to pass the distance of _S1 is 1-10 minutes; the time required for the mud to pass the distance of _S2 is 30s-5 minutes.

The method for rapid cleaning and dehydration of dredged sediment, wherein, the mass concentration of the low molecular weight cationic polymer is 0.1-1 wt%, and the mass concentration of the high molecular weight flocculant is 0.1-0.3 wt%.

The method for rapid cleaning and dehydration of dredged sediment, wherein the geotextile bag has an equivalent aperture O ₉₅ of 0.5 mm, a permeability Q ₅₀ of 25 l/m ² /s, and a wide strip tensile strength of 90 kN/m .

Beneficial effects: The treatment method for rapid cleaning and dehydration of dredged sediment proposed by the present invention uses pipeline secondary flocculation technology to significantly increase the particle size of mud particles, greatly improve dehydration efficiency and dehydration speed, and at the same time, the dehydration liquid meets environmental protection requirements. This technology has the advantages of short processing time, strong on-site operability, low equipment cost, low energy consumption and stable water quality of dehydration liquid, and has broad application prospects in the field of dredging sediment dewatering.

Description of drawings

Fig. 1 is a flow chart of a method for rapid cleaning and dehydration of dredged sediment provided by the present invention.

Detailed ways

The present invention provides a method for rapid cleaning and dehydration of dredged sediment. In order to make the purpose, technical solution and effect of the present invention clearer and clearer, the present invention will be further described in detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Please refer to Fig. 1, Fig. 1 is a kind of flow chart of the method for dredging sediment fast cleaning dehydration provided by the present invention, as shown in the figure, it comprises steps:

S10, cutting and agitating the bottom mud of the river bank through the cutter suction pump to form mud, and outputting the mud through pump force;

S20, transport the output mud through the pipeline, and add low molecular weight cationic polymer to the first branch on the pipeline close to the river bank to perform primary flocculation of the mud, and the low molecular weight cationic polymer is polyelectrolyte and polysaccharide-betaine one or more cationic polymers;

S30. Adding a high molecular weight flocculant at a position close to the end of the pipeline through the second branch to perform secondary flocculation of the mud. The high molecular weight flocculant is cationic polyacrylamide, anionic polyacrylamide and nonionic polyacrylamide one or more of

S40. Connect the end of the pipe to the geotextile bag, so that the floc flowing out of the pipe is directly injected into the geotextile bag for sedimentation and filtration, and the filtered clear water is directly discharged.

Specifically, the present invention proposes to use the mud transportation pipeline as a reactor, and make full use of the pipeline space and the hydraulic conditions generated by the flow of water to realize the conditioning of the mud by medicines, eliminating the need for subsequent dosing and mixing reaction processes, reducing land occupation, and saving treatment Time; the present invention also proposes pipeline secondary flocculation technology, which includes the primary flocculation process of low-molecular-weight cationic polymers and the secondary flocculation process of high-molecular-weight flocculants. Compared with the prior art, the floc particles formed by the present invention The particle size is increased by 1.5-7 times, which greatly improves the subsequent mechanical dehydration efficiency, and the geotextile bag filtration and dehydration speed can be increased by 2-100 times. Molecular weight cationic polymers form suspended micro-flocs with mud through electrical neutralization and weak bridging. The micro-flocs and high-molecular-weight flocculants further undergo a secondary flocculation process, and the flocs collide and aggregate into groups and grow rapidly. It is a coarse floc with a particle size of 50-300 μm; the pipeline secondary flocculation technology proposed by the present invention can also sweep the pollutants in the water together into the microfloc or adsorb on the surface of the microfloc and the large floc formed by the aggregation of the microfloc In the aggregate or adsorbed on the surface of large aggregates, it can realize the efficient capture of fine particles and dissolved pollutants in water. Compared with the existing technology, this technology does not need to carry out tail water treatment after treatment, and the water quality of the dehydration liquid is clear and the COD is low. At 40mg/L, to achieve clean dehydration.

The method for rapid cleaning and dehydration of dredged sediment provided by the present invention has high dehydration efficiency, short processing time, strong on-site operability, low requirements for filtering equipment, stable water quality of dehydration liquid, and meets environmental protection requirements. The field has broad application prospects.

In some embodiments, the molecular weight of the low molecular weight cationic polymer is less than 280,000, and the dosage of the low molecular weight cationic polymer is 0.3-1.2 g/kg.

In this example, the low-molecular-weight cationic polymer with a molecular weight of less than 280,000 can form suspended microflocs with mud through electrical neutralization and weak bridging, and the microflocs can adsorb pollutants in water to their surfaces , so that the efficient capture of fine particles and dissolved pollutants in mud water can be realized, that is, mud cleaning and dehydration can be realized. In this embodiment, only 0.3-1.2 g of low molecular weight cationic polymer needs to be added per 1 kg of mud to complete the first-stage flocculation process of the mud.

In some embodiments, the low molecular weight cationic polymer is one or more of polyelectrolyte and polysaccharide-betaine cationic polymer, wherein the polyelectrolyte is based on dimethyl diallyl ammonium chloride, methyl One or more of acryloyloxyethyltrimethylammonium chloride and acrylamideoxyethyldimethylbenzylammonium chloride is a cationic polymer obtained by homopolymerization or copolymerization; The polysaccharide-betaine cationic polymer is a polymer obtained through esterification with at least one of anhydrous betaine and betaine acid salt, taking chitosan or starch as a matrix.

In some embodiments, the molecular weight of the high molecular weight flocculant is greater than 8 million, and the dosage of the high molecular weight flocculant is 0.2-0.8 g/kg.

In this example, the high-molecular-weight flocculant with a molecular weight greater than 8 million can further undergo a secondary flocculation process with the microflocs obtained through primary flocculation. Coarse flocs of 50-300μm. The particle size of the flocs formed in this embodiment is 1.5-7 times larger than that of the microflocs, which can greatly improve the efficiency of subsequent mechanical dehydration, and the dehydration speed of bag filtration can be increased by 2-100 times. In this embodiment, only 0.2-0.8 g of high molecular weight flocculant needs to be added per 1 kg of mud to complete the secondary flocculation process of mud.

In some embodiments, the distance from the first branch to the second branch is set as S ₁ , the distance from the second branch to the end of the pipeline is set as S ₂ , and the S ₁ and S ₂ satisfy the following conditions : S ₁ = S _{1 mixing} +S _{1 reaction} , wherein, S _{1 mixing} is the distance of pipeline mud flow in the time of sufficient mixing of low molecular weight cationic polymer and mud, and S _{1 reaction} is the flocculation reaction time of low molecular weight cationic polymer and mud The distance of mud flow in the inner pipeline; S ₂ = S _{2 mixing} + S _{2 reaction} , wherein, S _{2 mixing} is the distance of pipeline mud flow within the time when the high molecular weight flocculant and mud are fully mixed, and S _{2 reaction} is the high molecular weight flocculant and mud flow distance The distance that pipeline mud flows during the flocculation reaction time.

In this embodiment, the flow velocity V ₁ of the mud in the pipeline is fixed, and when the time t ₁ that the mud passes through the distance of S ₁ is 1-10min, then the distance of S ₁ =V ₁ *t ₁ , the distance of S ₁ should be Satisfied that the mud and the low molecular weight cationic polymer are fully mixed and complete the first-order flocculation reaction; when the time t ₂ for the mud to pass through the distance of S ₂ is 30s-5min, then the distance of S ₂ = V ₁ *t ₂ , the distance of S ₂ It should be satisfied that the mud and the high molecular weight flocculant are fully mixed and the secondary flocculation reaction is completed.

In some embodiments, the mass concentration of the low molecular weight cationic polymer is 0.1-1 wt%, and the mass concentration of the high molecular weight flocculant is 0.1-0.3 wt%.

In some embodiments, the geotextile bag has an equivalent pore diameter O ₉₅ of 0.5 mm, a permeability Q ₅₀ of 25 l/m ² /s, and a strip tensile strength of 90 kN/m. The geotextile bag with selected parameters in this embodiment can effectively dehydrate the flocs, and the filtration and dehydration speed of the geotextile bag can be increased by 2-100 times.

The present invention is further explained below by specific embodiment:

Example 1

The dredged sediment sampled in this example is the sediment of the Yanghe River in Ma'anshan. The specific cleaning and dehydration process is as follows:

S1-cutter suction: suck the sediment from the bottom of the river through the cutter suction pump, the diameter of the pipeline is 0.2m, and the flow rate of the pipeline is 1.10m/s;

S2-Pipeline primary flocculation: the moisture content of the mud delivered in step S1 is about 95%, and the polydimethyldiallylammonium chloride aqueous solution (1wt%) with a molecular weight of 113,000 is pumped into the pipeline through a dosing pump , the dosage is 0.3g/kg, and the transmission distance in this section is 70 meters. At this time, polydimethyldiallylammonium chloride forms suspended microflocs with the mud through electrical neutralization and weak bridging;

S3-Pipeline secondary flocculation: pump an anionic polyacrylamide aqueous solution (0.3wt%) with a molecular weight of 10 million into the pipeline through a dosing pump, the dosage is 0.25g/kg, and the transmission distance of this section is 30 meters. When micro-flocs and high-molecular-weight anionic polyacrylamide undergo a secondary flocculation process, the flocs collide and aggregate into clusters, and rapidly grow into coarse flocs with a particle size of 50-300 μm;

S4-pipe end is connected with geotextile bag, and geotextile bag is the polypropylene woven cloth of _0.5mm for equivalent aperture O95, and total filter area is 36m ² , the coarse floc of output in step S3 flows through geotextile bag, filter after The water quality is clear, and the COD is lower than 40mg/L, which can realize clean dehydration.

Example 2

The dredged sediment sampled in this example is the sediment of the Yanghe River in Ma'anshan. The specific cleaning and dehydration process is as follows:

S1-cutter suction: suck the sediment from the bottom of the river through the cutter suction pump, the diameter of the pipeline is 0.2m, and the flow rate of the pipeline is 1.10m/s;

S2-Pipeline primary flocculation: the moisture content of the mud delivered in step S1 is about 95%, and the polydimethyldiallyl ammonium chloride aqueous solution (1wt%) with a molecular weight of 113,000 is injected by the dosing pump The dosage is 0.75g/kg, and the transmission distance in this section is 70 meters. At this time, polydimethyldiallylammonium chloride forms suspended microflocs with the mud through electrical neutralization and weak bridging;

S3-Pipeline secondary flocculation: pump an anionic polyacrylamide aqueous solution (0.3wt%) with a molecular weight of 10 million into the pipeline through a dosing pump, the dosage is 0.25g/kg, and the transmission distance of this section is 30 meters. When micro-flocs and high-molecular-weight anionic polyacrylamide undergo a secondary flocculation process, the flocs collide and aggregate into clusters, and rapidly grow into coarse flocs with a particle size of 50-300 μm;

S4-pipe end is connected with geotextile bag, and geotextile bag is the polypropylene woven cloth of _0.5mm for equivalent aperture O95, and the coarse floc of output in step S3 flows through geotextile bag, and the aqueous liquid water quality after filtering is clear, and COD is low At 40mg/L, clean dehydration can be achieved.

Example 3

The dredged sediment sampled in this example is the sediment of the Yanghe River in Ma'anshan. The specific cleaning and dehydration process is as follows:

S1-cutter suction: suck the sediment from the bottom of the river through the cutter suction pump, the diameter of the pipeline is 0.2m, and the flow rate of the pipeline is 1.10m/s;

S2-Pipeline primary flocculation: the moisture content of the mud delivered in step S1 is about 95%, and the polydimethyldiallyl ammonium chloride aqueous solution (1wt%) with a molecular weight of 113,000 is injected by the dosing pump The dosage is 1.2g/kg, and the transmission distance in this section is 70 meters. At this time, polydimethyldiallylammonium chloride forms suspended microflocs with the mud through electrical neutralization and weak bridging;

S3-Pipeline secondary flocculation: pump an anionic polyacrylamide aqueous solution (0.3wt%) with a molecular weight of 10 million into the pipeline through a dosing pump, the dosage is 0.25g/kg, and the transmission distance of this section is 30 meters. When micro-flocs and high-molecular-weight anionic polyacrylamide undergo a secondary flocculation process, the flocs collide and aggregate into clusters, and rapidly grow into coarse flocs with a particle size of 50-300 μm;

S4-pipe end is connected with geotextile bag, and geotextile bag is the polypropylene woven cloth of _0.5mm for equivalent aperture O95, and the coarse floc of output in step S3 flows through geotextile bag, and the aqueous liquid water quality after filtering is clear, and COD is low At 40mg/L, clean dehydration can be achieved.

Example 4

The dredged sediment sampled in this example is the sediment of the Yanghe River in Ma'anshan. The specific cleaning and dehydration process is as follows:

S1-cutter suction: suck the sediment from the bottom of the river through the cutter suction pump, the diameter of the pipeline is 0.2m, and the flow rate of the pipeline is 1.10m/s;

S2-Pipeline primary flocculation: the moisture content of the mud delivered in step S1 is about 95%, and the starch-betaine cationic polymer aqueous solution (0.6wt%) with a molecular weight of 278,000 is added by the dosing pump, and the dosage is It is 0.75g/kg, and the transmission distance of this section is 70 meters. At this time, polydimethyldiallylammonium chloride forms suspended microflocs with mud through electrical neutralization and weak bridging;

S3-Pipeline secondary flocculation: pump an anionic polyacrylamide aqueous solution (0.3wt%) with a molecular weight of 10 million into the pipeline through a dosing pump, the dosage is 0.25g/kg, and the transmission distance of this section is 30 meters. When micro-flocs and high-molecular-weight anionic polyacrylamide undergo a secondary flocculation process, the flocs collide and aggregate into clusters, and rapidly grow into coarse flocs with a particle size of 50-300 μm;

S4-pipe end is connected with geotextile bag, and geotextile bag is the polypropylene woven cloth of _0.5mm for equivalent aperture O95, and the coarse floc of output in step S3 flows through geotextile bag, and the aqueous liquid water quality after filtering is clear, and COD is low At 40mg/L, clean dehydration can be achieved.

Comparative example 1

The dredging bottom mud sampled in this comparative example 1 is the bottom mud of Ma'anshan Yanghe River, and the specific cleaning and dehydration treatment process is as follows: the medicament and dosage added in the first-level flocculation of the S-2 pipeline in comparative example 1 are blank, and the process of other stages is the same as that of the embodiment 2.

Comparative example 2

The dredged bottom mud sampled in this comparative example 1 is the bottom mud of Ma'anshan Yanghe River, and the specific cleaning and dehydration treatment process is as follows: the chemical agent and dosage added in the first-level flocculation of the S-3 pipeline in comparative example 2 are blank, and the process of other stages is the same as that of the embodiment 2.

The performance evaluation of the cleaning and dewatering process of the Yanghe river sediment in Ma'anshan in Examples 1-4 and Comparative Examples 1-2 is shown in Table 1.

Table 1 Test results

It can be seen from the results in Table 1 that the filtration speed of Example 1-4 of the present invention is 10-100 times higher than that of Comparative Example 1-2, and the quality of particles passing through the filter cloth is negligible. In contrast, Comparative Example 1-2 has a higher particle mass and a lower filtration efficiency.

The reason for the large difference in filtration and dehydration speed is that the two-stage flocculation process adopted by this technology uses polyelectrolyte or polysaccharide-betaine cationic polymer with high charge density and relatively low molecular weight to form tiny flocs with mud fine particles first. The micro flocs and high molecular weight flocculants further flocculate and bridge, and the nets quickly grow into coarse flocs. Due to the coarse floc particles, a filter cake layer is quickly formed in the mesh of the filter cloth at the initial stage of filtration, and the filter cake layer has a high porosity, and a large amount of water can quickly pass through the filter cake layer. However, the particle size of the flocs obtained by conditioning in the prior art is small, which blocks the gaps in the filter cloth and the filter cake layer during filtration, resulting in a slow dehydration rate. In addition, the turbidity and COD of the filtrate of Examples 1-4 are all small, and the filtrate is clear, while the filtrate of Comparative Example 1 is relatively dirty. If there are too many, the permeated mud still needs to be refluxed, and the dehydration efficiency will be reduced.

It should be understood that the application of the present invention is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above descriptions, and all these improvements and changes should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. A method for rapid clean dewatering of dredging substrate sludge, comprising the steps of:

cutting and stirring river bank sediment by a cutter suction pump to form mud, and outputting the mud by pump force;

transporting the output slurry through a pipeline, and adding a low molecular weight cationic polymer to perform primary flocculation on the slurry through a first branch on the pipeline close to the river bank, wherein the low molecular weight cationic polymer is one or more of polyelectrolyte and polysaccharide-betaine cationic polymer;

the method comprises the steps of (1) performing secondary flocculation on slurry at a position close to the tail end of a pipeline by adding a high molecular weight flocculant through a second branch, wherein the high molecular weight flocculant is one or more of cationic polyacrylamide, anionic polyacrylamide and nonionic polyacrylamide;

and connecting the tail end of the pipeline with the geotechnical cloth bag, directly injecting the flocs flowing out of the pipeline into the geotechnical cloth bag for sedimentation and filtration, and directly discharging the filtered clear water.

2. The method for rapid clean dewatering of dredging substrate sludge according to claim 1, wherein the low molecular weight cationic polymer has a molecular weight of less than 28 tens of thousands.

3. Method for rapid clean dewatering of dredging substrate sludge according to claim 2, characterized in that the low molecular weight cationic polymer is added in an amount of 0.3-1.2g/kg.

4. The method for rapid clean dewatering of dredging substrate sludge according to claim 1, wherein the high molecular weight flocculant has a molecular weight greater than 800 ten thousand.

5. The method for rapid clean dewatering of dredging substrate sludge according to claim 4, wherein the high molecular weight flocculant is added in an amount of 0.2-0.8g/kg.

6. The method for rapid clean dewatering of dredging sediment according to claim 1, wherein the polyelectrolyte is a cationic polymer obtained by homo-or copolymerization with one or more of dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, acrylamide oxyethyl dimethyl benzyl ammonium chloride as monomers; the polysaccharide-betaine cationic polymer is prepared by taking chitosan or starch as a matrix and carrying out esterification reaction with at least one of anhydrous betaine and betaine acid salt.

7. Method for rapid clean dewatering of dredging substrate sludge according to claim 1, characterized in that the distance from the first branch to the second branch is set to S ₁ The distance from the second branch to the tail end of the pipeline is S ₂ The S is ₁ And S is ₂ The following conditions are satisfied:

S ₁ ＝S _{1 mixing} +S _{1 reaction} Wherein S is _{1 mixing} Is the distance of the pipeline slurry flow within the time of fully mixing the low molecular weight cationic polymer and the slurry, S _{1 reaction} Is a low molecular weight cationic polymerizationThe distance of pipeline mud flow in the flocculation reaction time of the material and the mud;

S ₂ ＝S _{2 mixing} +S _{2 reaction} Wherein S is _{2 mixing} S is the distance of pipeline slurry flow in the time of fully mixing the high molecular weight flocculant with the slurry _{2 reaction} Is the distance that the pipeline slurry flows in the flocculation reaction time of the high molecular weight flocculant and the slurry.

8. Method for rapid clean dewatering of dredging substrate sludge according to claim 7, characterized in that the sludge is subjected to S ₁ The distance of (2) is 1-10min; mud passing S ₂ The time required for the distance of (2) is 30s-5min.

9. The method for rapid clean dewatering of dredging substrate sludge according to claim 1, wherein the mass concentration of the low molecular weight cationic polymer is 0.1-1wt% and the mass concentration of the high molecular weight flocculant is 0.1-0.3wt%.

10. Method for rapid clean dewatering of dredging substrate sludge according to claim 1, characterized in that the geotechnical cloth bag has equivalent pore diameter O ₉₅ 0.5mm, permeability Q ₅₀ 25l/m ² And/s, the tensile strength of the wide strip is 90kN/m.