River and lake ecological dredging construction method and treatment system

Abstract

This invention provides a method and system for ecological dredging of rivers and lakes, comprising the following steps: pre-treating sludge from land-based or water-based dredging; then performing sludge-water separation and sedimentation flocculation in a primary sedimentation tank to obtain precipitated flocculated sludge and supernatant; the supernatant is then treated in a wastewater treatment system; the precipitated flocculated sludge from land-based dredging undergoes mechanical pressure filtration for dewatering and consolidation; the treated sludge is used for backfilling in mines or pits and for ecological restoration, while the wastewater is returned to the primary sedimentation tank for treatment; or the precipitated flocculated sludge from water-based dredging undergoes geotextile bag filling for dewatering and consolidation; the treated sludge is used for wetland construction and ecological restoration, while the wastewater is returned to the primary sedimentation tank for treatment. The beneficial effects of this invention are: it is highly targeted to different particle sizes of sludge and different working conditions, has good treatment effect, high capacity, does not generate secondary pollution, and is safe, green, and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of ecological environment management, and in particular relates to a method and system for ecological dredging of rivers and lakes. Background Technology

[0002] The dredging area is located near shipping lanes and adjacent to the dike and wetlands on both sides. The construction site conditions are complex, and the requirements for water and waterway safety are high. The river and lake sediment contains a lot of garbage of various types and large sizes, making sorting and processing difficult. There is a large amount of silt that needs to be dehydrated and consolidated, and a large amount of tailwater that needs to be purified. The technical quality standards for dry mud solidification, tailwater purification and ecological restoration are high, and there are many challenges such as working in restricted areas, working near water and working in overlapping areas. Summary of the Invention

[0003] In view of this, the present invention aims to propose a method and system for ecological dredging of rivers and lakes to solve at least one technical problem in the background art.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] A method for ecological dredging of rivers and lakes includes the following steps: pre-treating the sludge from land-based or water-based dredging of rivers and lakes, then performing sludge-water separation and sedimentation flocculation in a primary sedimentation tank to obtain precipitated flocculated sludge and supernatant, with the supernatant entering a wastewater treatment system for treatment.

[0006] The sedimented and flocculated sludge from land discharge is mechanically dewatered and consolidated by filter press. The treated sludge is used for mine or pit backfilling and ecological restoration, while the wastewater is returned to the primary sedimentation tank for further treatment.

[0007] Alternatively, the sedimented and flocculated sludge from the water discharge can be filled with geotextile bags for dewatering and consolidation. The treated sludge can then be used for wetland construction and ecological restoration, while the wastewater can be returned to the primary sedimentation tank for further treatment.

[0008] Furthermore, the mechanical dewatering and consolidation of the sedimented and flocculated sludge discharged from land includes the following steps: taking samples from the primary sedimentation tank to obtain coarse sludge, medium-coarse sludge, medium sludge and fine sludge;

[0009] Coarse sludge, medium-coarse sludge, medium sludge, and fine sludge were concentrated and conditioned separately, and then filtered to obtain the treated sludge.

[0010] Furthermore, coarse sludge bottom sediment is in the front-end area of ​​the primary sedimentation tank;

[0011] Medium and coarse sludge bottom sediment is located at the junction of the front and middle parts of the pumping tank;

[0012] Medium-grained sludge is located in the middle area of ​​the primary sedimentation tank, while fine-grained sludge is located at the end area of ​​the primary sedimentation tank.

[0013] Sampling was conducted on-site from the front, middle and rear drainage areas of the pool, and the sludge particle size was measured in the laboratory to provide a basis for subsequent selection of reagent ratios, selection of concentration conditioning and filter press units;

[0014] The particle size of coarse sludge is 20 micrometers or larger;

[0015] The particle size of medium- and coarse-grained sludge is 16 to 20 micrometers;

[0016] The particle size of medium-sized sludge ranges from 14.27 micrometers to 16 micrometers;

[0017] The particle size of the microparticle sludge is less than 14.27 micrometers.

[0018] Furthermore, the thickening and conditioning of coarse sludge includes adding chemicals to the coarse sludge in a thickening tank, thickening, settling and flocculating the sludge, and then dewatering and solidifying it through a belt filter press unit. During this process, chemicals are also added to promote dewatering and solidification in the belt filter press. The moisture content of the solidified dry sludge is between 45% and 50%, and the thickness of the dry sludge cake is between 25 mm and 35 mm.

[0019] Furthermore / or, sampling of medium and coarse sludge requires close cooperation between the test personnel and the filter press operators to find the approximate boundary layer between different particle sizes, switch equipment combinations as needed, adjust the reagent ratio of the thickener and filter press unit in a timely manner, and change the direction of sludge transport in a timely manner.

[0020] And / or, the thickening and conditioning of medium and coarse sludge includes adding chemicals to the medium and coarse sludge, thickening, settling and flocculating the sludge; and dewatering and solidifying the sludge by using a belt filter press or a plate and frame filter press, with the solidified dry sludge having a moisture content of 45% to 50% and a dry sludge cake thickness of 25mm to 35mm.

[0021] Furthermore, in step S2, the medium-grained sludge thickening and conditioning treatment includes two thickening and conditioning processes before being transported to a plate and frame filter press unit for further processing.

[0022] When the proportion of surface particles with a diameter close to 16 micrometers exceeds 50% in medium-grained sludge, the frequency of sampling tests on the bottom sludge in the tank should be increased. Close cooperation between the testing personnel and the filter press operators is necessary to locate the approximate boundary layer between different particle sizes, adjust equipment combinations as needed, and promptly adjust the reagent ratios in the thickener and filter press unit, as well as change the sludge conveying direction. In other words, the filter press equipment should be selected and configured according to the actual situation.

[0023] A portion of the bottom mud with a particle size close to 16 micrometers is filtered by a belt filter press after adjusting the reagent ratio and concentrating and conditioning twice in a concentration tank and a transfer conditioning tank. At the same time, reagents are added again at the mud inlet of the belt filter press to promote the mud-chemical reaction, which can achieve a dry mud moisture content of 45% to 55% and a dry mud cake thickness of 20mm to 30mm.

[0024] Another portion of the bottom mud with a particle size of 14.27 micrometers ≤ and 16 micrometers is filtered by a plate and frame filter press after two thickening and conditioning processes: thickening and conditioning and intermediate conditioning. This process can achieve a solidified dry mud moisture content of 45% to 50% and a dry mud cake thickness of 35mm to 40mm.

[0025] And / or, the particulate sludge thickening and conditioning in step S2 includes sequentially using a thickening tank, a transfer conditioning tank, and a plate and frame filter press, while adjusting the reagent ratio, increasing the thickening and flocculation time of the sludge and reagent in the thickening tank and the transfer conditioning tank, and increasing the filtration time of the plate and frame filter press. The dry sludge moisture content can be controlled between 40% and 50%, and the sludge cake thickness can reach 30 mm.

[0026] Furthermore, the reagents added to the concentration tank of the belt filter press are: 0.5% PAC + 0.05% PAM or 0.09% PAC + 0.15% PAM;

[0027] And / or, the reagent added to the concentration tank of the plate and frame filter press is: 0.5% PAC + 0.05% PAM;

[0028] And / or, the reagent ratio for multiple supply points to the belt filter press is: 10% PAC + (0.1% to 0.2%) PAM;

[0029] And / or, the reagent ratio supplied to the slurry transfer and conditioning tank used in conjunction with the plate and frame filter press is: 10% PAC + (0.1% to 0.2%) PAM.

[0030] Furthermore, the sedimented and flocculated sludge from the above-water sludge discharge is filled into geotextile bags for dewatering and consolidation. This includes filling the geotextile bags with sedimented and flocculated sludge from the above-water sludge discharge, injecting flocculants during filling, and draining the water after filling. The filling, adding flocculants, and draining steps are repeated until the geotextile bags are full and then left to stand and consolidate.

[0031] The effluent is collected and transported to the primary sedimentation tank.

[0032] Furthermore, geotextile bags filled with sedimented and flocculated sludge from the surface discharge are laid along the river and lake. Once the bottom layer of geotextile bags has reached the requirements for filling and dewatering consolidation, the next layer of geotextile bags is filled and dewatered and consolidated.

[0033] Before filling the next layer of tubular bags, use inelastic ropes to secure the tubular bags.

[0034] And / or, the upper layer of geotextile bags should be laid between the two bottom layer geotextile bags that have been filled. After the bottom two closely arranged geotextile bags are filled, the gap between the geotextile bags is filled with geotextile to trap mud.

[0035] The filling of the tube bags should be carried out in stages. The filling height needs to be determined by pre-work test. The bottom few tube bags should be filled at the same time and alternately. The operator should use a smooth wooden stick or similar tool to tap and vibrate the surface of the tube bags regularly to accelerate the sludge filtration and volume reduction process.

[0036] A curved area is formed by geotextile bags around the river and lake, and it is connected to the bank. There are also several rectangular geotextile bags laid on the curved area.

[0037] An additional layer of geotextile bags and imitation wood piles is installed outside the arc-shaped area. A perimeter is then laid outside the wood piles, and a water treatment channel is formed between the perimeter, the geotextile bags, and the imitation wood piles.

[0038] The waterway is equipped with several algae collection platforms to collect algae that have formed due to eutrophication.

[0039] By separating the treatment area of ​​this application from other areas through enclosure, the eutrophication of other areas can be prevented from affecting the treatment area of ​​this application. Furthermore, the rectangular geotextile bags in this application can further divide the arc-shaped area to be treated into several areas, forming multiple ecological balances. If eutrophication occurs in one area, the impact on other areas is relatively small, and it can be dealt with in a timely manner.

[0040] If the arc-shaped area is treated, the above operation can be repeated using the arc-shaped area as the shoreline to continue treating the lake water in other areas, gradually promoting the treatment of the entire river and lake area and surrounding water system, reducing the difficulty of treatment, and allowing for zoning, which is convenient for management and aesthetically pleasing.

[0041] Furthermore, geotextile bags should be made of high-toughness geosynthetic materials, with joint strength ≥85KN / m and permeability Q. 50 ≥25L / (m 2 ·s);

[0042] And / or, the chemical mix ratio for the geotextile bags is: 0.5% PAC + (0.1%~0.2%) PAM;

[0043] Plant floating plants, stem plants, bulb and seed plants, and emergent herbaceous plants on the silt;

[0044] Preferably, the floating plants include water hyacinth and water celery;

[0045] Preferably, the stem, bulb, and seed plants include water lilies, lotus, water chestnuts, and fox nuts;

[0046] Preferably, emergent herbaceous plants include reeds, water onions, and cattails.

[0047] A treatment system for a river and lake ecological dredging construction method, the sludge system for land-based sludge discharge includes a sludge thickening tank system, a chemical dosing tank system, a transfer and conditioning tank system, and residual water recovery facilities;

[0048] The chemical dosing tank system is located on the side of the filter press unit near the chemical dosing tank in the filter press plant. The chemical dosing tank system, waste water recovery facilities, sludge thickening tank system, and transfer conditioning tank system are set up in sequence.

[0049] The wastewater treatment in this application adopts the method of the above-mentioned patent CN202310358217.9, which describes a method for the cascade separation, purification, and recycling of mud and water in a lakeside wetland area.

[0050] The sludge pretreatment of this application includes a sludge screening, filtering and diversion device (invention patent: ZL 202221191455.2) that dredges sludge using an environmentally friendly cutter suction dredger and transports it to an onshore sludge dump via a sludge discharge pipe. This device separates the bottom sludge from the garbage, temporarily stores the garbage and then performs harmless treatment, while the separated bottom sludge is discharged into an onshore primary sedimentation tank (sludge tank) through a pipe at the river and lake bottom sludge input port.

[0051] The primary sedimentation tank is the main container for the recovered bottom sludge, wastewater from the onshore filter press, and residual chemicals. The bottom sludge in the tank undergoes flocculation, sedimentation, and stratification through the dual action of "physical self-sedimentation + chemical reaction with environmentally friendly chemicals." The wastewater (effect water) enters the subsequent sedimentation and flocculation sludge system (achieving cascade separation of sludge and water, sedimentation and flocculation of sludge, and purification and clarification of effluent) until the purification meets the first-class discharge standard.

[0052] Compared with existing technologies, the river and lake ecological dredging construction method and treatment system described in this invention have the following advantages:

[0053] 1. This application adopts three key technological routes for "concentration and conditioning + dewatering and consolidation". Through scientific research and construction practice, this project simultaneously adopts three key technological routes for "concentration and conditioning of bottom sediment in concentration tank + dewatering and consolidation of belt filter press", "concentration and conditioning of bottom sediment in concentration tank + secondary conditioning of bottom sediment in transfer conditioning tank + dewatering and consolidation of plate and frame filter press", and "dewatering and consolidation of geotextile bags". These routes are implemented simultaneously in multiple scenarios and systems. They are highly targeted, effective, and have high capacity for different particle sizes of silt and different working conditions. They do not generate secondary pollution and are safe, green, and environmentally friendly. This provides technical parameters and quality standards for subsequent large-scale application in similar projects in the entire Chaohu Lake area and the entire Chaohu Lake basin.

[0054] 2. This application adopts three sludge dewatering and consolidation treatment processes: dredging the bottom sludge of Chaohu Lake using an environmentally friendly cutter suction dredger, transporting it to the land-based sludge discharge site and the water-based sludge discharge site via discharge pipes, screening out garbage and impurities using a garbage screening device for harmless treatment, and then allowing the separated mud and water to enter a primary sedimentation tank (sludge tank) for flocculation and sedimentation, before being transported to the mechanical filter press workshop at the land-based sludge discharge site for filter press consolidation and to the geotextile tubes at the water-based sludge discharge site for filling the sludge area for dewatering and consolidation. The moisture content met the design requirements, and the dry mud thickness met the construction and production targets: 1) In the onshore sludge discharge plant's filter press workshop, bottom mud with a particle size of 16μm or larger was dewatered and consolidated using a belt filter press, achieving a moisture content below 55% and an average mud cake thickness of approximately 3cm; 2) In the onshore sludge discharge plant's filter press workshop, bottom mud with a particle size below 16μm was dewatered and consolidated using a plate and frame filter press, achieving a moisture content below 50% and an average mud cake thickness of approximately 5cm; 3) In the aquatic sludge discharge plant, bottom mud with particle sizes above and below 16μm was dewatered and consolidated using geotextile bags, achieving a moisture content below 50%. These indicators not only met the construction quality requirements but also improved construction efficiency, achieving the project schedule control targets.

[0055] 3. This application develops geotextile bag dehydration and solidification and wetland construction technology, which solves the problem of the original design of water-based geotextile bag cofferdams, lakeside wetland micro-topography structures and the location conflict between the equipment for isolating and dredging blue-green algae in Chaohu Lake, solves the problem of poor functional effect of the original micro-topography bagged soil cofferdams, solves the problem of shallow beach and deep waterway layout in narrow areas, and solves the problem of tailwater treatment and discharge and avoids secondary pollution. Attached Figure Description

[0056] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0057] Figure 1 This is a schematic diagram of the construction process of a river and lake ecological dredging method according to an embodiment of the present invention;

[0058] Figure 2 This is a schematic diagram illustrating the placement of the geotextile bag according to an embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of a dredging project in the existing technology;

[0060] Figure 4 This is a schematic diagram of the dredging project layout for this application;

[0061] Figure 5 Photograph of dry mud cake solidified by belt filter press (approximately 10mm thick, moisture content ≤55%).

[0062] Figure 6Photos of filter cakes of different thicknesses filtered by a filter press unit;

[0063] Figure 7 Photograph of dry mud cakes consolidated by a plate and frame filter press (thick, up to 50mm thick, with a moisture content of up to 40%).

[0064] Figure 8 This is an overall schematic diagram of a sludge concentration and conditioning agent treatment system according to an embodiment of the present invention;

[0065] Figure 9 This is a schematic diagram of the sludge thickening tank device according to an embodiment of the present invention;

[0066] Figure 10 This is a side view of the sludge thickening tank device according to an embodiment of the present invention;

[0067] Figure 11 This is a top view of the sludge thickening tank device according to an embodiment of the present invention;

[0068] Figure 12 This is a schematic diagram of the dosing tank device according to an embodiment of the present invention;

[0069] Figure 13 This is a top view of the dosing tank device according to an embodiment of the present invention;

[0070] Figure 14 This is a side view of the dosing tank device according to an embodiment of the present invention;

[0071] Figure 15 This is a schematic diagram of the second water supply pipe of the dosing tank device according to an embodiment of the present invention;

[0072] Figure 16 This is a schematic diagram of the other side of the dosing tank device described in an embodiment of the present invention;

[0073] Figure 17 This is a schematic diagram of the transfer and conditioning tank device described in an embodiment of the present invention;

[0074] Figure 18 This is a side view of the transfer and preparation tank device described in an embodiment of the present invention.

[0075] Explanation of reference numerals in the attached figures: Detailed Implementation

[0076] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0077] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0078] The sludge system for onshore sludge discharge includes a sludge thickening tank device and a sludge thickening and conditioning agent treatment system, comprising a sludge thickening tank system 1, a dosing tank system 2, a transfer conditioning tank system 3, and a residual water recovery facility 7. The dosing tank system 2 is located on the side of the filter press unit in the filter press plant adjacent to the dosing tank. The dosing tank system 2, residual water recovery facility 7, sludge thickening tank system 1, and transfer conditioning tank system 3 are arranged sequentially. The dosing tank system 2 is equipped with a tank agitator 2-5 and a liquid transfer pump assembly 6. The sludge thickening tank system 1 is equipped with a drainage assembly and a backflushing assembly. The residual water recovery facility 7 is located on one side of the sludge thickening tank system 1. The sludge thickening tank system 1 is connected to the filter press unit via a pipeline, or the sludge thickening tank system 1 and the transfer conditioning tank system 3 are connected via a pipeline, and the transfer conditioning tank system 3 is connected to the filter press unit via a pipeline.

[0079] The wastewater recovery facility 7 collects and discharges into the main body of the wastewater recovery ditch in the plant area, and then flows into the onshore primary sedimentation tank 8. The wastewater (effect water) finally enters the effect water purification stage until it meets the first-level discharge standard. In addition, a certain concentration of reagents remains in the water collected in the wastewater recovery ditch. These reagents can still be fully utilized in the onshore primary sedimentation tank 8 and subsequent effect water purification stages, without being wasted. The wastewater (effect water) recovery facility consists of a belt filter press unit wastewater collection ditch, a plate and frame filter press unit wastewater recovery ditch, the main body of the plant area wastewater recovery ditch, the end outlet of the wastewater recovery ditch, and the onshore primary sedimentation tank 8. It can collect wastewater (effect water), recycle residual reagents, and allow the wastewater (effect water) to enter the subsequent purification and clarification steps until it meets the discharge standard, thus achieving resource reuse. The sludge thickening tank system 1 includes a sludge thickening tank body 1-1; a diversion component is located at the top of the tank body; a backflushing component is located at the bottom of the sludge thickening tank body 1-1; a bottom conical sludge collection bin 1-6 is provided at the bottom of the sludge thickening tank body 1-1, and the bottom of the bottom conical sludge collection bin 1-6 is supported by a bottom support structure 1-9; a sludge discharge pipe is connected to the bottom of the bottom conical sludge collection bin 1-6, and the sludge discharge pipe is connected to the transfer conditioning tank system 3 or a filter press unit; the diversion component includes a top diversion channel 1-2, which is located at the top of the sludge thickening tank body 1-1; the bottom of the top diversion channel 1-2 is connected to a top receiving diversion cylinder 1-3;

[0080] The bottom support structure 1-9 of the thickener tank includes several support rods, which are located below the conical sludge collection bin 1-6 at the bottom of the thickener tank. The residual water recovery facility 7 includes an overflow water recovery ditch 1-12 and an overflow pipe 1-11 at the top of the thickener tank. The overflow water recovery ditch 1-12 is located on one side of the sludge thickener tank body 1-1. One end of the overflow pipe 1-11 is connected to the top of the sludge thickener tank, and the other end is connected to the overflow water recovery ditch 1-12. The backflushing assembly includes two bottom backflushing pipes 1-7, which are located at the bottom of the conical sludge collection bin 1-6 at the bottom of the thickener tank. The bottom backflushing pipes 1-7 are connected to the water supply pipe. The backflushing pipes are at a 45-degree angle to the inner wall of the tank. The backflushing pipes are connected to the water pump and the water supply pipe, and the backflushing pipe inlets are high-pressure water spray nozzles.

[0081] A sludge thickening tank body 1-1 is provided with a sludge conveying pipe 1-4 on one side, and a first valve 1-8 is provided on the sludge conveying pipe 1-4; one end of the sludge conveying pipe 1-4 is connected to the sludge thickening tank body 1-1, and the other end is connected to the sludge in the sludge sedimentation tank; a chemical delivery pump assembly 6 is provided on one side of the sludge thickening tank body 1-1; the chemical delivery pump assembly 6 includes a chemical dosing pipe 1-5 and a second valve 1-13; the second valve 1-13 is provided on the chemical dosing pipe 1-5, one end of the chemical dosing pipe 1-5 is connected to the sludge thickening tank body 1-1, and the other end is connected to the chemical dosing tank system 2.

[0082] The top drainage channel 1-2 of the tank includes a rectangular section with a top opening and an arc-shaped section with a top opening, and the rectangular section and the arc-shaped section are connected; a pipe baffle is provided at the upper part of the arc-shaped section, and the chemical dosing pipe 1-5 and the sludge conveying pipe 1-4 of the concentration tank both enter the top drainage channel 1-2 of the tank through the pipe baffle; the bottom of the rectangular section with the top opening is connected to the material receiving drainage cylinder 1-3 at the top of the tank; a ladder and a working platform passage 1-10 are provided on one side of the sludge concentration tank; the working platform passage is located at the top of the ladder and is arc-shaped, and is connected to the ladder, and an operating panel is provided at the bottom of the working platform passage; the outer wall of the material receiving drainage cylinder 1-3 at the top of the tank is connected to the inner wall of the sludge concentration tank through a reinforcing plate.

[0083] The dosing tank system 2 includes a first dosing and dissolving tank 2-1 and a second dosing and dissolving tank 2-10. The second dosing and dissolving tank 2-10 is located on one side of the first dosing and dissolving tank 2-1. Both the first dosing and dissolving tank 2-1 and the second dosing and dissolving tank 2-10 are equipped with a tank stirring assembly 2-5 and a liquid delivery pump assembly 6. Both the second dosing and dissolving tank 2-10 and the first dosing and dissolving tank 2-1 are equipped with a tank fixing bracket 2-2 on one side. Both the first dosing and dissolving tank 2-1 and the second dosing and dissolving tank 2-10 are equipped with a water level alarm 2-4 on their inner walls. The volume of the first dosing and dissolving tank 2-1 is smaller than the volume of the second dosing and dissolving tank 2-10. PAM and PAC are added to both the first dosing and dissolving tank 2-1 and the second dosing and dissolving tank 2-10.

[0084] Alternatively, the reagents added to the second dosing and dissolving tank 2-10 may be PAM and PAC, while the reagent added to the first dosing and dissolving tank 2-1 may be PAM. The first dosing and dissolving tank 2-1 may replenish the PAM solvent concentration in the second dosing and dissolving tank 2-10 through the second water supply pipe 2-9. Alternatively, the reagents added to the second dosing and dissolving tank 2-10 may be PAM and PAC, while the reagent added to the first dosing and dissolving tank 2-1 may be PAC. The first dosing and dissolving tank 2-1 may replenish the PAC solvent concentration in the second dosing and dissolving tank 2-10 through the second water supply pipe 2-9. The medicine tank stirring assembly 2-5 includes a first stirring motor, a first output rod, and arc-shaped stirring blades; the first stirring motor is mounted on the middle of the first dosing and dissolving tank 2-1 or the second dosing and dissolving tank 2-10 via a first mounting bracket; the first output rod is connected to the output end of the first stirring motor, and several arc-shaped stirring blades are evenly arranged on the first output rod; the medicine delivery pump assembly 6 includes a medicine delivery pipe 2-8; the medicine delivery pipe 2-8 is located at the bottom of the first dosing and dissolving tank 2-1 or the second dosing and dissolving tank 2-10, and a booster water pump 2-6 is provided on the medicine delivery pipe 2-8.

[0085] The first and second dosing and dissolving tanks 2-1 and 2-10 are equipped with a water pump assembly 5. The water pump assembly 5 includes a first water supply pipe 2-3 and a second water supply pipe 2-9. The first water supply pipe 2-3 is connected to both the first and second dosing and dissolving tanks 2-1 and 2-10, respectively, and is equipped with a water supply valve. One end of the second water supply pipe 2-9 is connected to the first dosing and dissolving tank 2-1, and the other end is connected to the second dosing and dissolving tank 2-10. A water pump is installed on the second water supply pipe 2-9. A ladder is provided on one side of the tank fixing bracket 2-2, and a tank platform is provided on the upper part of the tank fixing bracket 2-2. A first control cabinet 2-7 is located on the tank platform. The controller in the first control cabinet 2-7 is electrically connected to the water level alarm 2-4, the first stirring motor, the water supply valve, and the water supply pump. The controller in the first control cabinet 2-7 uses existing PLC technology.

[0086] The transfer conditioning tank system 3 includes a first transfer conditioning tank body 3-1 and a second transfer conditioning tank body 3-8. The first transfer conditioning tank body 3-1 is located on one side of the second transfer conditioning tank body 3-8. Both the first and second transfer conditioning tank bodies 3-1 and 3-8 are equipped with a sludge inlet pipe 3-2 and a chemical inlet pipe 3-3, respectively. The sludge inlet pipe 3-2 is connected to the sludge thickening tank system 1, and the chemical inlet pipe 3-3 is connected to the chemical dosing tank system 2. The sludge inlet pipe 3-2 is equipped with a sludge inlet valve, and the chemical inlet pipe 3-3 is equipped with a chemical inlet valve. PAM and PAC are added to both the first and second transfer conditioning tank bodies 3-1 and 3-8. The ratio of PAM to PAC is different depending on the type of sludge being treated, allowing for the adjustment of sludge particles of different sizes. The intermediate conditioning tank system 3 has an intermediate conditioning and stirring assembly 3-5 in its middle section. The intermediate conditioning and stirring assembly 3-5 includes a second stirring motor, a second output rod, and intermediate conditioning and stirring blades. The second stirring motor is mounted on the middle of both the first intermediate conditioning tank body 3-1 and the second intermediate conditioning tank body 3-8 via a second mounting bracket. The second output rod is connected to the output end of the second stirring motor, and several intermediate conditioning and stirring blades are evenly arranged on the second output rod. An intermediate conditioning ladder 3-7 is located on one side of the intermediate conditioning tank body, and an intermediate conditioning platform is located at the top of the intermediate conditioning ladder 3-7. A second control cabinet 3-6 is located on the intermediate conditioning platform. The controller in the second control cabinet 3-6 is electrically connected to the mud-water input valve, the chemical input valve, and the second stirring motor. The controller in the second control cabinet 3-6 uses existing PLC technology.

[0087] Example 1

[0088] The sludge thickening tank body 1-1 of the sludge thickening tank system 1 is installed on a reinforced concrete foundation. The lower part of the foundation is supported by concrete pipe piles (bottom support structure 1-9 of the thickening tank). The sludge thickening tank bodies 1-1 are arranged in a straight line outside the filter press plant. There are 14 sets in total. The effective volume of each tank is about 120 cubic meters. They are made into cylindrical containers by welding and assembling 6 sets of Q235B annular steel plates (5mm thick) with a diameter of 4.6m. The total height of the sludge thickening tank 1-1 is approximately 8.5m. It is equipped with a ladder and working platform passage 1-10 for daily inspection and sampling (tank safety ladder, tank top safety walkway and guardrail, welded to the tank top reinforcement support); the lower support legs of the tank are 6 DN300 Q235B steel pipes (8mm wall thickness) (thickness support structure 1-9 of the thickening tank bottom), and 2 DN100 cross support steel pipes are welded between every two support legs to enhance the stability of the tank support; a DN200 thickening tank sludge conveying pipe 1-4 and a DN50 thickening tank chemical dosing pipe 1-5 are installed at the top of the tank, and a DN260 thickening tank top overflow pipe 1-11 is installed at the overflow port of the tank top. The sludge thickening tank system 1 is a temporary storage container for sludge. Sludge from the onshore primary sludge sedimentation tank is fed into the tank via a sludge conveying pipe by an environmentally friendly cutter suction dredger. Inside the tank, the sludge undergoes chemical flocculation, thickening, conditioning, and sedimentation. The concentrated sludge-water mixture with a higher concentration settles to the lower part of the tank and is then conveyed to the filter press unit for dewatering and solidification into dry sludge (with a moisture content of less than 55%) through the sludge outlet at the bottom of the conical sludge collection bin. The excess water generated during the filtration and solidification process needs to be recycled. The upper space of the tank is mainly filled with supernatant, while the supernatant exceeding the overflow height (i.e., residual chemicals and residual water from very fine sludge particles) is discharged through the top overflow pipe 1-11 of the thickening tank and drained into the overflow water recovery ditch 1-12 of the thickening tank through the lower port of the top overflow pipe 1-11.

[0089] A top drainage channel 1-2, resembling a sickle shape, is installed on the top of the sludge thickening tank 1-11. The arc-shaped section (the arc of the drainage channel is roughly the same as the arc of the outer edge of the tank body and is welded and fixed to the outer edge of the top of the tank) is about 3.5m long, 400mm wide, and 400mm high. One end of the rectangular section is welded and spliced ​​perpendicularly to the arc-shaped section at a 90-degree angle, and the other end is welded and fixed directly above the material receiving drainage cylinder on the top of the tank. The rectangular section is about 2.6m long, 400mm wide, and 400mm high. All sections are made of Q235B annular steel plates (3mm thick) and are welded and assembled. The top surface of the top drainage channel 1-2 is completely open. It receives the mud and water transported by the sludge conveying pipe 1-4 of the thickening tank and the chemical solution transported by the chemical dosing pipe-15 of the thickening tank through the installation of pipe baffles.

[0090] The bottom surface of the diversion channel has only a small, unsealed opening (approximately 390mm x 390mm) near the rectangular section close to the top receiving diversion cylinder of the tank. The remaining sections of the diversion channel are sealed by welded steel plates. The mud and liquid flow from this bottom opening into the top receiving diversion cylinder 1-3 directly below. The slope of the top diversion channel 1-2 is approximately 2.5%, facilitating the guidance of the mud and liquid to the top receiving diversion cylinder 1-3. The sickle-shaped diversion channel also utilizes its curvature and angle to reduce the scouring force of the mud and liquid, slowing the flow velocity and preventing overflow.

[0091] (3) Top receiving and diversion cylinder 1-3: A top receiving and diversion cylinder 1-3 is installed at the center of the top of the sludge thickening tank 1-1. The diameter is about 500mm and the length of the cylinder is about 2m. The outer wall of the diversion cylinder is fixed by a set of upper and lower reinforcing steel plate support assemblies (the steel plate supports are evenly distributed along the ring of the cylinder, with a total of 8 supports). The two ends of the steel plate supports are welded to the inner wall of the thickening tank and the outer wall of the diversion cylinder, respectively. The steel plate supports are 200mm wide and 5mm thick. The length of the steel plate is the distance between the tank and the cylinder.

[0092] The top of the diversion cylinder extends approximately 200mm above the top of the concentration tank. A 3mm thick steel plate is laid on the upper surface of the steel support of the top receiving diversion cylinder 1-3. The steel plate platform is a ring-shaped steel plate with an inner diameter of approximately 502mm, fitted around the outside of the diversion cylinder and welded to it. The outer diameter of the steel platform is approximately 2.5m, serving as a ladder and access passageway 1-10 to the work platform. A 1.2m high safety guardrail is welded to the outer edge of the platform. After the diversion channel 1-2 at the top of the tank slows down the flow rate and impact of the muddy water and liquid, the top receiving diversion cylinder 1-3 further reduces the impact of the muddy water and liquid flow. It can accurately collect and guide the muddy water or liquid into the tank, guiding it into the central part of the tank and then spreading outwards, preventing excessive settling and ensuring the overall stability of the tank.

[0093] Thickening tank sludge conveying pipe 1-4: A DN200 Q235B steel thickening tank sludge conveying pipe 1-4 with a wall thickness of 3mm is installed along the outer wall of the sludge thickening tank 1-1 from the bottom to the top of the tank. One end of the thickening tank sludge conveying pipe 1-4 is connected to the dredging vessel discharge pipe or the sludge pump conveying pipe, and the mud and water are transported from the onshore primary sedimentation tank to the sludge thickening tank system 1. The other end of the thickening tank sludge conveying pipe 1-4 is located directly above the top of the tank body, above the top diversion channel 1-2. The pipe opening is bent 180 degrees and extends downward into the diversion channel, which is the confluence end for conveying mud and water. Dosing pipe 1-5 for concentration tank: A DN50 Q235B steel dosing pipe with a wall thickness of 2mm is installed along the outer wall of the sludge concentration tank 1-1 from the bottom to the top of the tank. One end of the dosing pipe 1-5 is connected to the delivery pipe of the dosing tank system. The other end of the dosing pipe 1-5 is directly above the drainage groove 1-2 at the top of the tank. The pipe opening is bent 180 degrees and extends downward into the drainage groove, which is the end of the delivery and collection of the liquid.

[0094] Conical sludge collection bin 1-6 at the bottom of the thickener: A conical sludge collection bin is also welded and assembled at the bottom of the thickener. The upper diameter of the cone is the same as that of the tank body, and the cone height is about 2m. It is the main storage area for receiving mud and chemical solution, thickening and conditioning mud and water, and sedimentation. The mud concentration here is relatively high and viscous. The bottom of the bin is equipped with a mud outlet and a backflushing device, which is also the outlet of the thickened mud. The mud outlet is connected to the mud conveying pipe and gate valve. The mud conveying pipe is connected to the mud pump, which can transport the thickened mud to the filter press unit for dewatering and solidification. After the thickened mud in the collection bin is discharged and transported, the remaining supernatant at the top can also be discharged into the overflow water recovery ditch 1-12 of the thickener tank through the mud conveying pipe tee connected to the mud outlet at the bottom of the bin. Backflush pipes 1-7 at the bottom of the thickener: To prevent the sludge concentrated and settled in the conical sludge collection chamber at the bottom of the thickener from clogging the sludge outlet, two sets of backflush pipes 1-7 are arranged on both sides of the bottom of the conical chamber, above the sludge outlet, with the pipe openings extending into the sludge collection chamber. The two sets of backflush pipes 1-7 are arranged symmetrically, with the backflush pipes forming a 45-degree angle with the inner wall of the tank. The backflush pipes are connected to the water pump and water supply pipe. The backflush pipe openings are high-pressure water nozzles, which can spray high-pressure water as needed to appropriately improve the sludge concentration at the sludge outlet of the sludge collection chamber. The water pressure range is 0.3 to 1.0 MPa, which can be adjusted by a pressure pump. The high-pressure water flow drives the concentrated sludge in the sludge collection chamber to flow, adjusts the flow rate, prevents clogging at the bottom of the sludge collection chamber, and promotes the smooth flow of sludge into the sludge outlet.

[0095] Various pipes attached to the thickener are equipped with gate valves and pressure gauges as needed to open the pipes and regulate the pressure of the conveyed slurry and chemicals. The bottom support structure 1-9 of the thickener tank: The total height of the container for the bottom backflushing pipe of the thickener tank is approximately 8.5m. The lower support legs of the tank are composed of six DN300 Q235B steel pipes (8mm wall thickness). Additionally, two DN100 cross-bracing steel pipes are welded between every two support legs to enhance the stability of the tank support. Ladder and work platform passage 1-10: The sludge thickener tank 1-1 is equipped with a safety ladder for daily inspection and sampling, a safety walkway on the top of the tank, a work platform, and guardrails (the ladder and work platform passage 1-10 are welded to the reinforced support on the top of the tank). The work platform is equipped with a video monitoring system and lighting, facilitating video information collection, daily inspection and safety management, and maintenance and testing.

[0096] Overflow pipe 1-11 at the top of the thickener tank: The overflow pipe 1-11 at the top of the thickener tank is an accessory and structure of the sludge thickener tank. It is installed on the outer wall of each thickener tank body, facing the side of the filter press plant where the overflow water recovery ditch 1-12 is located. The overflow pipe is a DN260 Q235B steel pipe with a wall thickness of 3mm. The pipe is welded to the outer wall of the sludge thickener tank body by supporting connecting steel plates. The upper end of the pipe is connected to the overflow port at the top of the overflow water recovery ditch 1-12. The wastewater flowing out enters the overflow pipe through the upper part of the pipe and flows down. The outlet of the overflow pipe faces the overflow water recovery ditch 1-12 of the thickener tank. The outlet of the pipe makes a 135-degree bend to reduce the speed of the water flow and prevent mud and water from splashing out. There are 14 thickener tanks installed on the outside of the filter press plant, equipped with 14 overflow pipes. The wastewater overflowing from each overflow pipe will flow into the overflow water recovery ditch 1-12 of the thickener tank. The overflow water recovery ditch 1-12 of the thickener tank is located below the pipe and is specifically designed to receive the wastewater flowing down from the overflow pipe.

[0097] The overflow water recovery ditch 1-12 of the concentration tank is made of C20 plain concrete and is cast on site. It is 100m long, 0.6m wide and 0.6m deep, with a slope of about 1.5%. The concrete ditch wall is about 100mm thick and the bottom plate is about 150mm thick. The structure is safe, reliable and leak-proof. The pedestrian passage is covered with cast iron grating. Located between the filter press plant and the thickener, this open ditch is scientifically and rationally laid out. It fully considers and utilizes the limited and narrow space between the thickener foundation and the filter press plant foundation. It extends straight along the 14-unit thickener to the main body of the wastewater recovery ditch in the plant area, specifically collecting the wastewater discharged from the overflow pipe of the thickener. The wastewater is then collected and discharged into the main body of the overflow water recovery ditch 1-12, and then flows into the onshore primary sedimentation tank. The wastewater (effect water) finally enters the effect water purification stage until it meets the first-level discharge standard. In addition, a certain concentration of reagents remains in the water collected in the wastewater recovery ditch. These reagents can still be fully utilized in the onshore primary sedimentation tank and subsequent effect water purification stages, without being wasted.

[0098] Example 2

[0099] The dosing tank system 2 is used to add chemicals to the sludge thickening tank system 1, the transfer conditioning tank system 3, the belt filter press unit, and the plate and frame filter press unit. Its function is to add chemicals, dissolve and mix chemicals, and transport chemicals. A total of 12 sets are installed and arranged in the filter press plant of the onshore sludge discharge site, near the sludge thickening tank system 1.

[0100] Dosing and dissolving tank 2-1: The tank is made of Q235B steel. Each set of dosing and dissolving tank 2-1 is divided into two independent chambers, which can simultaneously and independently mix two different dosages and ratios of drugs to meet the needs of different working conditions. The dimensions of the 1# rectangular tank are 2500mm×1800mm×3000mm (length×width×height) with a wall thickness of 3mm. The dimensions of the 2# rectangular tank are 1800mm×1800mm×1000mm (length×width×height) with a wall thickness of 3mm. It comes with a steel operating platform and maintenance ladder. Its function is to add, dissolve and mix drugs.

[0101] (2) Medicine box fixing bracket 2-2 and operating platform: made of Q235B steel with a wall thickness of 3mm. The operating platform and maintenance ladder serve as fixing brackets for components and boxes, storing control cabinets, and also for maintenance, observation, daily maintenance and climbing up and down ladders.

[0102] (3) Stirring pump assembly: The motor power is 5kw, and it is installed on the fixed bracket above the medicine tank dosing port. The steel fixed bracket is made of Q235B profile. The lower end of the stirring pump assembly is a stirring blade connected by a steel bearing. Its function is to drive the stirring blade at the lower end to dissolve and stir the medicine and adjust the medicine solution after water and medicine are added to the medicine tank.

[0103] (4) Water supply pipe and gate valve: φ50mm galvanized water pipe and ball valve, which provide water source for the chemical dissolving tank.

[0104] (5) Water level alarm 2-4: Float type automatic water level alarm, which is used to automatically monitor the water level in the medicine tank. When the water level is too low or too high, it will automatically alarm to remind the operator to take action.

[0105] (6) Booster pump 2-6: The power is 3kw and it can provide a maximum pressure of 1.6mpa. It is installed at the bottom of the medicine tank outside the medicine tank. The input end pipe is connected to the bottom of the medicine tank and the output end pipe is connected to the medicine delivery pipe 2-8. Its function is to pressurize and deliver the medicine to the dosing point.

[0106] (7) Control cabinet device: It is composed of a multi-component electrical control cabinet device, which contains automatic and manual control systems and operation buttons. It is installed on the steel operating platform of the dosing and dissolving tank. Its function is equipment control, mainly controlling the stirring pump assembly, booster pump, water level alarm 2-4 and video monitor, etc.

[0107] (8) Chemical delivery pipeline 2-8: The material is Q235B galvanized steel pipe, which can withstand a maximum pressure of 1.6 MPa, with a diameter of DN100 and a wall thickness of 4.0 mm. The chemical delivery pipeline 2-8 is connected to the output end of the booster pump 2-6 and its function is to deliver the chemical solution to the dosing point.

[0108] (9) In addition, the dosing tank system 2 adds, mixes, dissolves and transports environmentally friendly agents (PAM+PAC). The ratio is derived from pre-production production tests and process monitoring sampling test data to meet different working conditions and different purification stages. It is supplied to each dosing point with strong targeting, precision and reliability.

[0109] Example 3

[0110] III. Transfer and Preparation Tank System 3

[0111] For sludge with a particle size of less than 16 micrometers, an additional transfer and conditioning tank 3-1 is set up, which has the function of transfer and secondary conditioning. That is, after the first concentration and conditioning in the thickener, if the dewatering and consolidation output and dry sludge moisture content of the belt filter press are not well controlled, the transfer and conditioning tank system 3 can be selected to carry out secondary transfer and conditioning of sludge and water, and then transport it to the plate and frame filter press for dewatering and consolidation, so as to achieve the goal of meeting the construction period requirements for dewatering and consolidation output and the design requirements for moisture content.

[0112] (1) Tank: The transfer and conditioning tank 3-1 is a cylindrical tank made of Q235B steel with a diameter of 2m and a height of 2m. It is used to store mud and water that need to be transferred and conditioned. After adding the medicine, it is stirred and conditioned in the tank.

[0113] (2) Sludge input pipe 3-2: DN200 Q235B steel sludge conveying pipe with a wall thickness of 2mm. One end of the sludge conveying pipe is connected to the outlet of the sludge pump pipe at the bottom of the thickening tank, and the other end is connected to the transfer conditioning tank, which can input sludge into the tank.

[0114] (3) Drug input pipe 3-3: DN50 Q235B steel dosing pipe with a wall thickness of 2mm; one end of the dosing pipe is connected to the dosing tank delivery pipe, and the other end is connected to the transfer conditioning tank, which can deliver the drug solution into the tank.

[0115] (4) Mud output pipe 3-4: DN200 Q235B steel mud conveying pipe with a wall thickness of 2mm. One end of the mud conveying pipe is connected to the mud conveying pump pipe of the transfer conditioning tank, and the other end is connected to the mud conveying pump pipe that conveys mud and water to the plate and frame filter press unit. It can convey the conditioning mud and water from the transfer conditioning tank to the plate and frame filter press unit.

[0116] (5) Transfer conditioning and stirring assembly 3-5: The power is 5kw. It is installed on the second mounting bracket of the transfer conditioning and stirring assembly above the tank. The steel fixed bracket is made of Q235B profile. The lower end of the transfer conditioning and stirring assembly is a stirring blade connected by a steel bearing. Its function is to drive the blade at the lower end to rotate and stir and condition the mud and water and the chemical solution, promote the reaction between the mud and water and the chemical solution, make the mud and water flocculate and settle, and adjust its concentration to increase the output of the plate and frame filter press when dewatering and solidifying the mud and water, and reduce the moisture content of the dry mud cake.

[0117] (6) Second control cabinet 3-6: It is composed of a multi-component electrical control cabinet device, which contains automatic and manual control systems and operation buttons. It is installed on the steel operating platform of the tank. Its function is equipment control, mainly controlling the transfer conditioning and stirring components 3-5 and the water level alarm 2-4. The second controller 3-6 adopts the existing PLC technology.

[0118] (7) Transfer and conditioning ladder: Made of Q235B steel with a wall thickness of 3mm. The function of the operating platform and maintenance ladder is to serve as a fixed support for components and tanks, to store the control cabinet, and to perform functions such as inspection, observation, daily maintenance and climbing up and down the ladder.

[0119] Example 4

[0120] Wastewater recovery facility 7: mainly composed of open ditches for collecting wastewater (effect water) from various locations, namely, open ditches for collecting overflow water (waste water) from concentration tanks, open ditches for collecting wastewater from belt filter press units, open ditches for collecting wastewater from plate and frame filter press units, the main body of the wastewater recovery ditch in the plant area, the end outlet of the wastewater recovery ditch, and the onshore primary sedimentation tank 8, etc. It can collect wastewater (effect water), recycle residual chemicals, and allow the wastewater (effect water) to enter subsequent purification and clarification steps until it meets the discharge standards and is reused as a resource.

[0121] The wastewater (tailwater) recovery ditch is constructed of C20 plain concrete cast on-site, with a total length of approximately 300m, a width and depth of 0.6m x 0.6m, a slope of approximately 1.5%, a concrete ditch wall thickness of approximately 100mm, and a bottom slab thickness of approximately 150mm. The structure is safe, reliable, and leak-proof. Cast iron grating covers are installed at pedestrian walkways. The overflow (wastewater) recovery ditch for the concentration tank is located between the filter press plant and the concentration tank. Its layout is scientifically sound, fully utilizing the limited space between the concentration tank foundation and the filter press plant foundation. It extends straight along the 14-unit concentration tank to the main body of the wastewater recovery ditch in the plant area, specifically collecting wastewater discharged from the concentration tank overflow pipe. This wastewater flows into the main body of the wastewater recovery ditch in the plant area and then into the onshore primary sedimentation tank 8. Other wastewater collection ditches for belt filter press units, plate and frame filter press units, and other wastewater collection ditches in the plant area are also included. The main bodies of the water recovery open ditches are distributed near the various equipment sites inside the filter press plant, specifically to collect the residual water (effect water) generated by each equipment. All of these are collected at the end of the residual water recovery open ditches and finally discharged into the onshore primary sedimentation tank 8 (sludge tank). The residual water (effect water) then enters the effect water purification stage until it meets the first-level discharge standard. In addition, a certain concentration of reagents remains in the water collected in the residual water recovery open ditches. These reagents can still be fully utilized in the onshore primary sedimentation tank 8 and subsequent effect water purification stages to participate in water purification and are not wasted.

[0122] The wastewater recovery ditch end outlet consists of a 600mm diameter corrugated pipe that runs across the site road and is buried below the roadbed. One end is connected to the end of the wastewater recovery ditch, and the outside of the pipe opening is sealed with waterproof concrete to prevent water seepage. The other end of the pipe extends into the onshore primary sedimentation tank 8, and the wastewater (tailwater) can flow directly into the onshore primary sedimentation tank 8 through the pipe opening to complete the wastewater (tailwater) recovery.

[0123] Land-based primary sedimentation tank 8: Located within the cofferdam between the land-based sludge discharge area and the lakeside wetland, the cofferdam is constructed of clay and covered with a common composite geotextile (two layers of fabric and one membrane, specifications: 200g / m³). 2 ) / 0.5mm / (200g / m 2The cofferdam has a bottom width of 33.1m, a top width of 2m, and a height of 7m. The sedimentation tank has an effective area of ​​approximately 18,225 square meters and a volume of approximately 91,125 cubic meters. It can store approximately 82,012 cubic meters of mud and water, which is more than 24 hours of sludge removal. The average sedimentation and flocculation time of sludge in the land sedimentation tank is more than 24 hours. Therefore, there will be more than 1 / 3 of the surface clear water in the surface flow. The onshore primary sedimentation tank 8 receives the slurry water after screening and filtration at the river and lake bottom sediment input port. It is the main receiving tank for the dredged slurry of Chaohu Lake, hence it is also commonly known as the slurry tank. In addition, the residual water from the onshore pressure filter solidification production workshop and the overflow water from the concentration tank are also returned to the onshore primary sedimentation tank 8. The residual water contains environmental protection agents left over from the sludge solidification process. The agents can promote the sludge in the sedimentation tank, which not only realizes the reuse of residual agents and avoids waste of agents, but also improves the flocculation and sedimentation of flocculated sludge. The downstream of the onshore primary sedimentation tank 8 is other multi-stage sedimentation tanks for the purification and clarification of residual water (effect water).

[0124] The system is arranged in the area of ​​the filter press and sedimentation tank in the onshore sludge discharge site. The 14 sets of sludge thickening tanks (System 1) are arranged in a straight line outside the filter press, with the dosing tank inside the filter press on one side and the onshore sludge sedimentation tank and tailwater sedimentation tank on the other side. The 12 sets of dosing tanks are arranged in a straight line inside the filter press, with the filter press unit on one side and the thickening tank outside the filter press on the other side. The 6 sets of transfer conditioning tanks are arranged near the plate and frame filter press units inside and outside the plant, and are arranged side-by-side with the nearby thickening tanks. The thickening tanks and dosing tanks are separated by the steel structure exterior wall of the filter press. A tailwater recovery ditch is constructed between the foundation of the exterior wall and the foundation of the thickening tanks. Another tailwater recovery ditch is constructed between the dosing tanks inside the plant and the filter press unit. The ditches converge outside the plant and connect to the onshore primary sedimentation tank (sludge tank). The factory is equipped with video surveillance cameras, lighting equipment, and environmental monitoring devices inside and outside. Safety railings and passageways are provided for operations near water, edges, and at heights.

[0125] Example 5

[0126] Onshore sludge discharge: During the initial temporary construction phase, the system was arranged in the area of ​​the filter press plant and sedimentation tank in the onshore sludge discharge site, according to the plan. 14 sets of thickening tanks were arranged in a straight line in the outer side of the filter press plant, with the dosing tank inside the filter press plant on one side and the onshore sludge sedimentation tank and tailwater sedimentation tank on the other side. 12 sets of dosing tanks were arranged in a straight line in the inner side of the filter press plant, with the filter press unit on one side and the thickening tank outside the filter press plant on the other side. 6 sets of transfer conditioning tanks were arranged near the plate and frame filter press unit inside and outside the plant, and were arranged side by side with the thickening tanks in the vicinity. The thickening tanks and dosing tanks were separated by the steel structure outer wall of the filter press plant. A tailwater recovery ditch was built between the foundation of the outer wall of the plant and the foundation of the thickening tank. Another tailwater recovery ditch was built between the dosing tank inside the plant and the filter press unit. The ditches converged outside the plant and connected to the onshore primary sedimentation tank 8 (sludge tank). The factory is equipped with video surveillance cameras, lighting equipment, and environmental monitoring devices inside and outside. Safety railings and passageways are provided for operations near water, edges, and at heights.

[0127] According to the method of this invention, firstly, the lakeside wetland area adjacent to the outer side of the Chaohu Dam at the project site is surveyed and marked out according to the land acquisition boundary. The original humus soil of the lakeside wetland is stripped and temporarily stored. The aquatic plants and animals of the wetland are relocated and properly resettled as required (to be reclaimed and restored after completion). Then, the onshore sludge disposal site is constructed according to the final implementation plan and layout diagram. That is, the onshore sludge disposal site filter press workshop and plant facilities are constructed on one side, and the onshore primary sedimentation tank 8 (sludge tank) cofferdam and other sedimentation tanks of various levels are constructed on the other side. After the pre-production production test is completed, formal production can be carried out according to the process flow. The specific operation mode is as follows:

[0128] An optimized sediment screening scheme was developed, and a screening device was constructed to separate mud and waste: The sediment from Chaohu Lake was dredged by an environmentally friendly cutter suction dredger and transported to an onshore sludge discharge site via a sludge discharge pipe. A sludge screening, filtering and diversion device (invention patent: ZL202221191455.2) was used to separate the sediment from the waste. The waste was temporarily stored and then subjected to harmless treatment, while the separated sediment was discharged into the onshore primary sedimentation tank 8 (sludge tank) through the pipeline at the river and lake sediment input port.

[0129] During the dredging process, the diffusion distance of suspended solids in the water must not exceed 50m, and the dredging depth error must be controlled within 0 to -5cm, ensuring that the dredged sediment concentration is not less than 10%. Under-dredging is not permitted, and the dredged sediment concentration must be guaranteed to be not less than 10%. Because the cutter head disturbance during dredging can cause sludge particles from the lakebed to spread to surrounding water areas, potentially causing secondary pollution, the impact range of the cutter suction dredger during dredging must be strictly controlled. The Dutch IHC environmentally friendly cutter suction dredger used is equipped with environmental protection devices, including an anti-spreading protective cover, an environmentally friendly cutter head, and an oil-water separator, minimizing disturbance to the water body during operation. The dredger is also equipped with a GPS global positioning system, depth sounder, pollution detection device, trench cross-section monitoring device, and dredging trajectory display device, ensuring dredging accuracy and concentration, controlling the diffusion distance of suspended solids in the water to not exceed 50m during dredging, and preventing secondary pollution.

[0130] The primary sedimentation tank 8 is the main containment tank for the recovered bottom sludge, wastewater from the onshore filter press, and residual chemicals. Under the dual action of "physical self-settling + chemical reaction of environmentally friendly chemicals", the bottom sludge in the tank flocculates, settles, and stratifies. The wastewater (effect water) enters the subsequent sedimentation and flocculation sludge system (to achieve cascade separation of mud and water, sedimentation and flocculation of sludge + purification and clarification of effect water) until the purification reaches the first-class discharge standard.

[0131] According to the process flow method of this invention, the bottom mud of Chaohu Lake is first dredged by an environmentally friendly cutter suction dredger, and then transported to the primary mud sedimentation tank of the onshore mud discharge site through the mud discharge pipe. After that, it needs to be concentrated and conditioned, dosing chemicals, secondary mixing and conditioning (optional), concentrated flocculation, and sedimentation of flocculated sludge. It is then transported to the filter press unit in the filter press workshop of the project's onshore mud discharge site for filter pressing, dewatering and consolidation. The residual water (tailwater) is recycled, the tailwater is purified and treated, and the resources are reused. The consolidated dry mud is recycled for resource utilization, mine pit backfilling and ecological restoration.

[0132] The onshore primary sedimentation tank (sludge tank) is the main onshore container for the dredged sediment of Chaohu Lake. It is also the wastewater recovery container for the onshore filter press solidification production workshop. The place where the sediment sludge undergoes preliminary "physical + chemical" flocculation and sedimentation in different areas and layers is located. It is also the transfer storage tank for the sediment after temporary storage, which will be transported to the concentration tank and filter press solidification production workshop.

[0133] The onshore primary sedimentation tank is located within a dike between the onshore sludge discharge area and the lakeside wetland. The dike is constructed of clay and covered with a common composite geotextile (two layers of fabric and one membrane, with a specification of 200g / m²). 2 ) / 0.5mm / (200g / m 2The cofferdam has a bottom width of 33.1m, a top width of 2m, and a height of 7m. The sedimentation tank has an effective area of ​​approximately 18,225 square meters and a volume of approximately 91,125 cubic meters. It can store approximately 82,012 cubic meters of mud and water, which is more than 24 hours of sludge removal. The average sedimentation and flocculation time of sludge in the land sedimentation tank is more than 24 hours. Therefore, there will be more than 1 / 3 of the surface clear water in the surface flow.

[0134] The sediment at the onshore sludge dump was dewatered and consolidated using a filter press, with a total volume of 1.288 million cubic meters of sediment treated.

[0135] The onshore primary sedimentation tank receives the slurry water after screening and filtration at the input port of river and lake bottom sediment. It is the main receiving tank for dredged mud from Chaohu Lake, hence it is also commonly known as a mud tank. In addition, the waste water from the onshore pressure filter solidification production workshop is also returned to the onshore primary sedimentation tank. The waste water contains environmentally friendly agents remaining from the sludge solidification process. These agents can promote the sludge in the sedimentation tank, which not only realizes the reuse of residual agents and avoids waste of agents, but also improves the flocculation and sedimentation effect of bottom sediment.

[0136] The sludge cascade sedimentation and flocculation process employs a combination of physical and chemical sedimentation. In the sedimentation tank, the bottom sludge undergoes initial flocculation and sedimentation through physical settling and chemical reactions. Larger particles (above 20 micrometers) settle at the front of the tank, while medium-sized particles (14.27 to 16 micrometers) settle in the middle, and extremely fine particles (below 14.27 micrometers) settle at the rear. The higher-concentration sludge at the bottom of the sedimentation tank is transported by a small environmentally friendly cutter suction dredger or small sludge pump to an onshore sludge thickening tank for further flocculation and sedimentation. The sludge is then transported through the thickening tank pump system pipeline. The system supplies dewatering and solidification into dry sludge cakes in the onshore filter press solidification production workshop. The dry sludge cakes are then transported to the mine via a belt conveyor system for resource reuse in mine ecological restoration. The residual water from the solidification process in the onshore filter press solidification production workshop flows back into the sedimentation tank. The residual environmental protection agents and a small amount of fine particulate bottom sludge in the residual water flow again in the sedimentation tank. The fine particulate bottom sludge continues to settle and flocculate sludge, while the surface tailwater flows towards the overflow dam. The relatively clear but still fine particulate bottom sludge on the surface of the sedimentation tank is diverted by the diversion weir along with the tailwater and flows into the secondary sedimentation tank (clear water tank) through the overflow weir of the overflow dam, continuing into the next stage of sedimentation and flocculation sludge process.

[0137] In summary, coarse-grained sludge (particle size greater than 20 micrometers) is deposited in the front area of ​​the primary sedimentation tank; medium-grained sludge (particle size 14.27 to 16 micrometers) is deposited in the middle area; and extremely fine-particle sludge (particle size less than 14.27 micrometers) is deposited and flocculated in the rear area. The sludge transported to the thickening and conditioning system of the filter press plant comes from these three locations. Before transport, the site technician will take samples from the front, middle, and rear drainage areas of the tank according to the work plan, and determine the sludge particle size in the laboratory. This provides a basis for subsequent selection of reagent ratios and selection of thickening, conditioning, and filter press units.

[0138] The original design was optimized by adding six sets of plate and frame filter presses specifically for dewatering and consolidating fine sludge particles smaller than 16μm. The original belt filter press units were only suitable for processing bottom sludge particles larger than 16 micrometers. If the particle size was smaller than 16 micrometers, it would be difficult to control the moisture content and cake thickness of the consolidated dry sludge, failing to meet design requirements (consolidated dry sludge moisture content ≤ 55%) and project schedule requirements (consolidated dry sludge cake thickness ≥ 20mm, and average equipment operating time of over 10 hours to meet the schedule). During the trial production on site, for fine particles with a diameter of less than 16 micrometers, the agent added to the concentration tank of the belt filter press was 0.5% PAC + 0.05% PAM. The moisture content of the dry sludge after filter pressing and consolidation was about 60%, which exceeded the design requirement. Moreover, the thickness of the dry sludge after consolidation was less than 10mm, and the thinnest was only about 2mm. The fine particles of bottom sludge were lost with the residual water (tailwater) through the filter cloth of the belt filter press and could not be successfully consolidated and filtered, so the normal mass production target could not be achieved and the construction period could not be guaranteed.

[0139] Therefore, the project additionally configured 6 plate and frame filter press units specifically to assist in the treatment of bottom mud with a particle size of less than 16 micrometers. These units can filter bottom mud with a particle size of less than 16 micrometers to a mud cake that meets the design requirements (the design requirement is that the moisture content of the solidified dry mud is ≤55%). Moreover, the thickness of the solidified dry mud cake is ≥20mm, and the thickest can reach 50mm. However, the working method of the plate and frame filter press unit is to fill the mud once, continuously filter once, and after the filter solidification is completed, fill the mud again and filter and solidify the dry mud again. Unlike the belt filter press, which continuously fills the mud and continuously filters and solidifies, the plate and frame filter press has a pause in its working time and cannot work continuously. The reagents added to the concentration tank of the plate and frame filter press are: 0.5% PAC + 0.05% PAM; however, using a plate and frame filter press can overcome the problems of low efficiency and difficulty in controlling the moisture content of dry mud when using a belt filter press to process bottom mud with a particle size of less than 16 microns. It can assist the belt filter press in specifically treating fine particle bottom mud and improve the dry mud solidification qualification rate.

[0140] Meanwhile, in order to improve the concentration and flocculation effect of fine particle sediment, the project also developed an additional transfer conditioning tank to add a concentration and flocculation process for fine particle sludge, added flocculants to cope with the working conditions of sediment with different particle sizes, and added on-site sampling tests at three sludge sampling points in the primary sedimentation tank to differentiate the working conditions and select appropriate agents and equipment.

[0141] The specific details are as follows:

[0142] (1) If only the bottom sludge at the front of the tank is to be pumped out, and its particle size is above 20 micrometers, the normal operation mode will be adopted. That is, the bottom sludge from the primary sedimentation tank will be transported to the sludge thickening tank system 1 for chemical addition, thickening, sedimentation and flocculation of sludge, and then supplied to the belt filter press unit in the filter press plant for dewatering and solidification. During this period, chemicals will also be added in a timely manner to promote the dewatering and solidification of the belt filter press and improve the efficiency and quality of dry sludge solidification. Under normal circumstances, only the thickening tank and the belt filter press unit are used for sludge thickening, conditioning and filter dewatering and solidification. The chemicals added to the thickening tank supplied to the belt filter press unit are: 0.5% PAC + 0.05% PAM. The moisture content of the solidified dry sludge can reach between 45% and 50%, and the thickness of the dry sludge cake can reach 25mm to 35mm. Under the full-load operation of 14 thickening tanks and 12 belt filter press units, the schedule requirements are met and the quality is up to standard.

[0143] (2) If it is necessary to pump out the bottom sludge at the junction of the front and middle parts of the pool, and the particle size is mixed with that of 20 micrometers or more and 16 micrometers or less and 20 micrometers or less, when the bottom sludge particle size is all above 16 micrometers, the 14 sets of concentration tank system and the 12 sets of dosing tank system (each set has 2 independent dosing chambers) can be connected in series or in parallel groups to supply the 12 sets of belt filter press units and 6 sets of plate and frame filter press units in the filter press plant to operate at full load. The bottom sludge concentration and conditioning, dosing and mixing and transportation, sludge filter dewatering and consolidation, dry sludge transportation and external transportation, waste water (tailwater) purification, resource recycling and utilization and ecological restoration construction are carried out according to the process.

[0144] That is, all particles larger than 20 microns are filtered and solidified using 12 belt filter presses, and the reagents added to the concentration tank of the belt filter press are: 0.5% PAC + 0.05% PAM.

[0145] For particles with a diameter of 16 microns to 20 microns, six plate and frame filter presses are used. This utilizes the advantages of both types of equipment, resulting in high efficiency and preventing situations where the dry sludge moisture content is lower than the design specifications or the dry sludge cake thickness is less than 20mm, thus avoiding rework and low efficiency. However, on-site sampling personnel will need to increase the frequency of sampling and testing.

[0146] Generally, the particle size in the upper part is above 20 micrometers, while the particle size in the middle and lower parts is between 16 and 20 micrometers. It is necessary for the test personnel and the filter press operators to work closely together to find the approximate boundary layer between different particle sizes. This allows for the switching of equipment combinations at any time, and timely adjustment of the reagent ratio in the thickener and filter press unit, as well as timely changes in the direction of slurry transport.

[0147] When using a plate and frame filter press to treat fine particulate sediment, the reagents added to the thickening tank of the plate and frame filter press are: 0.5% PAC + 0.05% PAM. Two slurry thickening and conditioning processes are required: first, thickening and conditioning in the thickening tank, and then thickening and conditioning in the intermediate conditioning tank. The slurry is then transported to the plate and frame filter press to fill the slurry for filter pressing, dewatering, and solidification. Therefore, the overall time taken by the plate and frame filter press is longer than that of the belt filter press, but it has a higher quality of treatment for fine particles. Among them, after optimizing equipment configuration and reagent ratio, the plate and frame filter press unit can achieve a maximum dry mud thickness of 50mm and an optimal dry mud moisture content of 40% to 50%, which is 15% to 5% lower than the design target; the belt filter press can achieve a solidified dry mud cake thickness of 25mm to 30mm, with a maximum of 30mm, and a dry mud moisture content of 45% to 55%, which is about 10% lower than the design target, thus improving production capacity and efficiency.

[0148] (3) When the bottom sludge in the middle area of ​​the pumping tank has a particle size of 14.27 micrometers ≤ 16 micrometers, it can be completely concentrated and conditioned twice before being transported to the plate and frame filter press unit for treatment; however, when the amount of sludge in the middle of the tank is large, and there is a large amount of bottom sludge close to 16 micrometers on its surface, the sampling test frequency of the bottom sludge in the tank can be increased. The test personnel and the filter press operators need to work closely together to find the approximate boundary layer of different particle sizes, so that the equipment combination can be changed at any time. Then, the reagent ratio of the thickening tank and the filter press unit should be adjusted in time, and the direction of sludge transportation should be changed in time. That is, the filter press equipment should be selected according to the actual situation: a part of the bottom sludge with a particle size close to 16 micrometers. After adjusting the reagent ratio and undergoing two concentration and conditioning processes in the concentration tank and transfer conditioning tank, the sludge is still filtered using a belt filter press. At the same time, reagents are added again at the sludge inlet of the belt filter press to promote the sludge-chemical reaction and dewatering and consolidation. This can achieve the optimal dry sludge moisture content of 45% to 55% and a dry sludge cake thickness of 20mm to 30mm. Another portion of the bottom sludge with a particle size of 14.27 microns to 16 microns is filtered using a plate and frame filter press after two concentration and conditioning processes in the concentration tank and transfer conditioning tank. This can achieve the optimal consolidated dry sludge moisture content of 45% to 50% and a dry sludge cake thickness of 35mm to 40mm.

[0149] (4) When fine particulate bottom mud (particle size below 14.27 micrometers) exists at the end of the pumping tank, the combination of a concentration tank + transfer conditioning tank + plate and frame filter press is used. At the same time, the reagent ratio is adjusted to increase the concentration and flocculation time of mud and medicine in the concentration tank and transfer conditioning tank, and increase the filtration time of the plate and frame filter press. The moisture content of dry mud can be controlled between 40% and 50%, and the optimal mud cake thickness can reach about 30mm, achieving good working efficiency.

[0150] (5) When the concentration tank, chemical tank, transfer conditioning tank, or filter press unit needs to be shut down for maintenance in rotation, different groups of single or multiple concentration tanks, chemical tanks, transfer conditioning tanks, or filter press units can be selected in series or parallel for combined production operations. This can avoid large-scale shutdowns that would delay production progress, meet normal maintenance needs, and also meet production needs under different working conditions. By increasing the number of equipment combinations, day and night staggered production can be achieved, adjusting the dredging and conveying volume of the Chaohu Lake bottom sediment dredger, the concentration volume of the concentration tank, the dredging volume of the transfer concentration tank, and the sludge storage volume in the onshore primary sedimentation tank. This allows for flexible adjustment of the chemical solution ratio, conditioning of the slurry concentration, and the conveying volume and speed, facilitating the adjustment and control of the construction period, improving efficiency and quality, and ensuring safe production. Its normal production process is similar to the above two operating modes.

[0151] For situations involving rotating shutdowns for maintenance or staggered production to adjust equipment, the equipment can be freely combined according to site needs. The general principle is: concentration tank + belt filter press unit, concentration tank + transfer tank + plate and frame filter press unit, concentration tank + transfer tank + belt filter press unit. Each type of equipment and facility should have at least one unit corresponding to one other unit. Alternatively, multiple concentration tanks + multiple transfer tanks can correspond to one filter press unit, or multiple concentration tanks + multiple transfer tanks can correspond to multiple filter press units.

[0152] The onshore primary sedimentation tank, commonly known as the mud tank, is equipped with a floating safety channel for on-site sampling personnel. The sampling personnel can use long-handled sampling tubes to reach different water depths to collect mud and water samples from different depths, which are then sealed in sampling bottles for laboratory testing. Particle size analysis is performed using a Malvern laser particle size analyzer (Hydro 2000MU(A)).

[0153] Example 6

[0154] The sediment from Chaohu Lake is dredged using an environmentally friendly cutter suction dredger and transported via discharge pipes to an onshore discharge site. A sludge screening, filtering, and diversion device (invention patent: ZL 202221191455.2) separates the sediment from the waste. The waste is temporarily stored and then undergoes harmless treatment, while the separated sediment is discharged through a pipe at the lake sediment input port into an onshore primary sedimentation tank (sludge tank). This process also includes the use of geotextile tubes for dredging, effluent recycling, purification, sedimentation, and flocculation of sludge in the water-based geotextile tube filling area. In short, the flocculated sediment is then dredged, filtered, and solidified using geotextile tubes, treating a total of 300,000 m³ of sediment.

[0155] The geotextile bags are made of high-toughness geosynthetic materials, and the joint strength and permeability must meet the design requirements. The bags have a three-dimensional filtration structure, with the ability to allow water to flow in both the plane and vertically, effectively intercepting particulate matter loss. They also possess long-term durability and UV resistance, ensuring the safety of silt filling operations. During silt filling, PAM and PAC dehydration aids are added according to the chemical ratio. The moisture content of the solidified dry sludge should reach the design standard of less than 50%. The dehydrated and solidified dry sludge is used in situ for the construction of lakeside wetlands. The tailwater (residual water) filtered out by the geotextile bags is recycled to a tailwater sedimentation tank for purification treatment. After the tailwater meets the purification standards, it is discharged into the Nanfei River and Chaohu Wetland.

[0156] The geotextile bags used to consolidate the dried mud from the sludge dump are utilized as planting soil for greening, creating lakeside wetlands in situ, planting aquatic plants, releasing benthic animals, and creating a lakeside ecological wetland with reeds as the dominant species, thus purifying water quality and improving the ecological environment.

[0157] The geotextile bags used to consolidate the dried mud from the sludge dump are utilized as planting soil for greening, creating lakeside wetlands in situ, planting aquatic plants, releasing benthic animals, and creating a lakeside ecological wetland with reeds as the dominant species, thus purifying water quality and improving the ecological environment.

[0158] Considering that the geotextile bags surrounding the outer ring of the sludge dump cofferdam will serve as part of the wetland's wave-dissipating submerged dike after construction, these geotextile bags are required to have high strength, UV resistance, and scour resistance. The outer ring of the sludge dump cofferdam uses GT750 type geotextile bags with a geotextile lining, while the inner filling area of ​​the sludge dump cofferdam, for cost-saving purposes, uses GT500 type geotextile bags. The GT500 type geotextile bags should be made of high-toughness geosynthetic materials, with a joint strength ≥85KN / m and a permeability of Q. 50 ≥25L / (m 2 The geotextile tubes (·s) feature a three-dimensional filtration structure, allowing for both planar and vertical permeability. They effectively trap particulate matter, possess long-term durability and UV resistance, ensuring the safety of filling operations. The geotextile tubes are available in two sizes: 61.4m × 20m and 61.4m × 10m. Their technical specifications are shown in the table below.

[0159] GT500 geotextile tube technical specifications

[0160]

[0161] The laying location was determined, and the laying followed the principle of laying from the center outwards and from the bottom layer to the top layer. The geotextile bags were laid starting from the center of the sludge discharge site and then gradually extended outwards. To ensure the water tightness and stability of the cofferdam later, each geotextile bag was overlapped by 3 meters: the first bag overlapped the second, the second overlapped the third, and so on. The length of each section of the geotextile bag was determined according to the site topography, and the joints were left on the straight sections of the cofferdam. This project used layered geotextile bags for filling.

[0162] To prevent slippage and displacement of the geotextile bags during filling, after the bottom layer of geotextile bags is laid, pine stakes are driven around the bags using an excavator, and ropes are used to connect and secure the side loops of the geotextile bags to the pine stakes. This ensures that the bottom layer of geotextile bags will not shift due to water buoyancy or strong winds, thus achieving the purpose of fixing the position of the geotextile bags. The upper layer of geotextile bags is then secured to the bottom layer of filled geotextile bags by binding them together with the side loops.

[0163] The chemical mixing ratio for geotextile tube bags is: 0.5% PAC + (0.1%~0.2%) PAM;

[0164] The filling of geotextile bags includes: connecting the branch pipes of the multiple filling ports of the bottom layer geotextile bags to the main delivery pipe; simultaneously transporting the initially flocculated sludge through multiple branch pipes to fill the geotextile bags; each pipe is equipped with a flow meter and an independent gate valve to ensure the stability of the sludge entering the geotextile bags. The geotextile bags positioned at the center of the bottom layer must not shift during filling, otherwise it will cause significant deviations in the filling positions of subsequent geotextile bags. During the bottom layer filling, workers manually tread on the top surface of the bags to rearrange the soil particles and make them more compact, ensuring uniform and flat filling, accelerating the drainage and consolidation speed of the bags, and allowing sufficient time for the entire geotextile bag to reach slurry shielding and consolidate and dewater.

[0165] After each geotextile bag is filled, multiple cuffs of the bag should be sealed with geotextile tape. After each repeated filling, the top elevation and axial deviation of the geotextile bag should be inspected. For qualified bags, the filling process should be repeated until the entire bag is filled to meet the design requirements before sealing the cuffs.

[0166] When the geotextile tubes reach their maximum height of 2.5 meters during the initial filling, filling is stopped, and drainage begins. As water continues to drain from the tubes and their height decreases, a second filling is initiated, and so on, until the geotextile tubes are fully filled, typically 8-10 times. During subsequent fillings, as the solids content of the silt inside the tubes increases, the filling time for each filling is continuously shortened, and the amount of drained water decreases. The drained water is collected by a surrounding water collection system and returned to a sedimentation tank. No curing is required during the silt consolidation process; the tubes are left outdoors to stand for approximately 30 days to reach the required level.

[0167] To save space during construction, this project adopts a multi-layer stacking filling method. This means that the next layer of geotextile bags is filled and dehydrated only after the bottom layer has reached the required level of filling and dehydration. Before filling, the next layer of geotextile bags is secured with inelastic ropes, and the bottom layer is reinforced with denser securing to ensure stability between the layers. The next layer of geotextile bags should be laid between two already filled bottom layer geotextile bags, staggered from the bottom layer. After the two bottom layer geotextile bags are filled, the gap between them is sealed with geotextile fabric filled with mud to provide a flat foundation for subsequent filling. The geotextile bag filling should be carried out in stages to prevent bursting. Pre-construction tests are required to determine the filling height, etc. During repeated filling, to ensure full filling, several bottom layer geotextile bags are filled alternately. Operators can use smooth wooden sticks or similar tools to periodically tap and vibrate the surface of the geotextile bags to accelerate the sludge filtration and volume reduction process. Height measurement benchmarks were set up to control the filling elevation, strictly controlling the maximum safe filling height of the tubular bags. Dedicated personnel were assigned to regularly measure the filling height, filling flow rate, and filling volume of the tubular bags to prevent them from bursting under the combined ultimate pressure of filling pressure and the weight of the silt. Construction records were maintained. Simultaneously, intercepting ditches were dug inside the tubular bags to collect seepage water and pump it out centrally.

[0168] Based on the analysis of plant botanical characteristics, plants with the following features were selected: 1. Strong vitality, strong adaptability to the environment, and well-developed root systems; 2. Large biomass and rapid growth; 3. Seasonal dormancy; 4. Short growth cycle. Locally dominant varieties should also be given priority when selecting plants for artificial wetlands. Commonly used plants in artificial wetlands are divided into: 1. Floating plants, such as water hyacinth and water celery; 2. Stem, bulb, and seed plants, such as water lilies, lotus, water chestnuts, and water caltrops; 3. Emergent herbaceous plants, such as reeds, water onions, and cattails. This project selected reeds, a highly adaptable aquatic plant with a well-developed root system, for planting.

[0169] During the planting of aquatic plants, the multiple layers of geotextile bags used in this application allow for direct implantation of the plants into the soil. After rapid activation, the plants are concentrated and piled in the topsoil to adjust soil pH and improve plant survival rate. CBM compound probiotics are added to improve soil microbial substrate, at a dosage of 10 kg / mu (5 g / m²). 2 The dosage should be diluted ten times more than that of ordinary plants to form a liquid before use, approximately 60ml / m³. 2 Aquatic plants do not require base fertilizer; top dressing should use CBM compound probiotics instead of organic fertilizer to avoid polluting the water.

[0170] A curved area is formed by geotextile bags around the river and lake, and it is connected to the bank. There are also several rectangular geotextile bags laid on the curved area.

[0171] An additional layer of geotextile bags and imitation wood piles is installed outside the arc-shaped area. A perimeter is then laid outside the wood piles, and a water treatment channel is formed between the perimeter, the geotextile bags, and the imitation wood piles.

[0172] The waterway is equipped with several algae collection platforms to collect algae that have formed due to eutrophication.

[0173] By separating the treatment area of ​​this application from other areas through enclosure, the eutrophication of other areas can be prevented from affecting the treatment area of ​​this application. Furthermore, the rectangular geotextile bags in this application can further divide the arc-shaped area to be treated into several areas, forming multiple ecological balances. If eutrophication occurs in one area, the impact on other areas is relatively small, and it can be dealt with in a timely manner.

[0174] If the arc-shaped area is treated, the above operation can be repeated using the arc-shaped area as the shoreline to continue treating the lake water in other areas, gradually promoting the treatment of the entire river and lake area and surrounding water system, reducing the difficulty of treatment, and allowing for zoning, which is convenient for management and aesthetically pleasing.

[0175] Examples 1-6 are located in the nearshore lake area outside the confluence of the Nanfei River and Chaohu Lake, distributed on the left side of the Nanfei River estuary and the Chaohu Lake navigation channel, with a total dredging area of ​​5.52 km². 2 The dredging depth in the pilot area was 20-50cm, with an average dredging depth of approximately 0.29m, and the total dredging volume was 1.588 million cubic meters. 3 .

[0176] The project site includes one onshore sludge disposal site and one offshore sludge disposal site. The bottom sludge in the onshore sludge disposal site is dewatered and consolidated using a filter press, with a total sludge volume of 1.288 million m³ treated. 3 The consolidated dried sludge was transported to the Guojiashan mine pit in Chaohu City for mine pit backfilling and ecological restoration. The bottom sediment at the water-based sludge dump was dewatered and consolidated using geotextile bags, with a total treatment volume of 300,000 m³. 3The consolidated dry mud is used in situ for the construction of lakeside wetlands.

[0177] The wastewater (residual water) purification and treatment project covers an area of ​​approximately 14.29 million m3. The wastewater (residual water) discharge standards meet the Class I discharge standards in the "Integrated Wastewater Discharge Standard" (GB8978-1996), namely SS (suspended solids concentration) <70mg, COD (chemical oxygen demand) <100mg, ammonia and helium <15mg, and the pH value should meet the standards of the "Surface Water Environmental Quality Standard" (GB3838-2002). The qualified residual water is discharged to the lakeside wetland and Nanfei River via a wetland pumping station.

[0178] The moisture content of the solidified dry mud meets the requirements of the "Standard for Geotechnical Testing Methods" (GB / T50123-2019), with a moisture content of less than 55% for belt filter press and less than 50% for geotextile tube bags. Furthermore, it should be ensured that the mud does not turn into mud after being soaked in water during subsequent storage, transportation, mine restoration, and wetland construction.

[0179] Compared with traditional methods, this method boasts advantages such as scientific design, reasonable structural layout, reliable process flow, rapid and efficient operation, structural safety, environmental protection and energy saving, economic applicability, and ease of use. It is suitable for large-scale ecological dredging, large-volume sediment transport, large-volume sediment treatment through cascade sedimentation and flocculation, large-volume purified and clarified effluent, strong integrated production and processing capacity of various facilities in the onshore sludge discharge site, large volume of compliant effluent environmentally friendly recycling and discharge, high level of environmental protection for lakeside wetlands, low reliance on permanent equipment and facilities, high work efficiency, convenient chemical dosing and spraying, rapid sedimentation and flocculation of sludge, thorough filtration and interception, good and fast purification and clarification effect, low operating costs, simple and safe operation, energy saving and environmental protection, and wide applicability. It can adapt to the operational needs of waterfront areas, confined spaces, and overlapping work areas, helping to eliminate safety hazards, greatly improving construction production efficiency, reducing construction costs, ensuring construction safety, and preventing secondary environmental pollution. It achieves the goals of green and environmentally friendly construction in lakeside wetland areas, protecting the wetland ecological environment, and conserving and utilizing water resources in an environmentally friendly manner, aligning with the national green building design concept. This invention can be widely applied to the full sedimentation and flocculation of sludge or sewage in lakes, rivers, wetlands, towns, factories and other fields, as well as the chemical addition and flocculation of residual water (tailwater) after dewatering and solidification, sludge filtration, purification and clarification, and environmental recycling. It can be promoted and applied in similar projects.

[0180] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A river and lake ecological dredging construction method, characterized in that: The process includes the following steps: pre-treating the sludge from land-based and water-based dredging of rivers and lakes; then performing sludge-water separation and sedimentation flocculation in a primary sedimentation tank to obtain precipitated flocculated sludge and supernatant; the supernatant then enters the wastewater treatment system for further treatment. The sedimented and flocculated sludge from land discharge is mechanically dewatered and consolidated by filter press. The treated sludge is used for mine or pit backfilling and ecological restoration, while the wastewater is returned to the primary sedimentation tank for further treatment. The sedimented and flocculated sludge from the water-based sludge discharge is dehydrated and consolidated by filling geotextile bags. The treated sludge is used for wetland construction and ecological restoration, while the wastewater is returned to the primary sedimentation tank for further treatment. The sedimentation and flocculation sludge from land-based sludge discharge is mechanically dewatered and consolidated by filter press, including the following steps: sampling is taken from the primary sedimentation tank to obtain coarse sludge, medium-coarse sludge, medium sludge and fine sludge; Coarse sludge, medium-coarse sludge, medium sludge and fine sludge are concentrated and conditioned respectively, and then filtered to obtain the treated sludge. Coarse sludge bottom sediment is located in the front area of ​​the primary sedimentation tank; Medium and coarse sludge bottom sediment is located at the junction of the front and middle parts of the pumping tank; Medium-grained sludge is located in the middle area of ​​the primary sedimentation tank, while fine-grained sludge is located at the end area of ​​the primary sedimentation tank. Sampling was conducted on-site from the front, middle and rear drainage areas of the pool, and the sludge particle size was measured in the laboratory to provide a basis for subsequent selection of reagent ratios, selection of concentration conditioning and filter press units; The particle size of coarse sludge is 20 micrometers or larger; The particle size of medium- and coarse-grained sludge is 16 to 20 micrometers; The particle size of medium-sized sludge ranges from 14.27 micrometers to 16 micrometers; The particle size of the microparticle sludge is less than 14.27 micrometers; The thickening and conditioning of coarse sludge includes adding chemicals to the coarse sludge in the thickening tank, thickening, settling and flocculating the sludge, and then dewatering and solidifying it through a belt filter press. During this process, chemicals are also added to promote dewatering and solidification in the belt filter press. The moisture content of the solidified dry sludge is between 45% and 50%, and the thickness of the dry sludge cake is between 25mm and 35mm. Sampling medium and coarse sludge requires close cooperation between the test personnel and the filter press operators to find the approximate boundary layer between different particle sizes, switch equipment combinations as needed, adjust the reagent ratio of the thickener and filter press unit in a timely manner, and change the direction of sludge transport in a timely manner. The treatment and conditioning of medium and coarse sludge includes adding chemicals, concentrating, settling and flocculating the medium and coarse sludge; and dewatering and solidifying the sludge by using belt filter press and plate and frame filter press. The moisture content of the solidified dry sludge is between 45% and 50%, and the thickness of the dry sludge cake is between 25mm and 35mm. For the thickening and conditioning of medium-sized sludge, when the surface layer of medium-sized sludge contains more than 50% particles with a diameter close to 16 micrometers, the frequency of sampling tests on the bottom sludge in the tank should be increased. Close cooperation between the testing personnel and the filter press operators is necessary to locate the approximate boundary layer between different particle sizes, adjust the equipment combination as needed, and promptly adjust the reagent ratios in the thickening tank and filter press unit, as well as change the sludge conveying direction. In other words, the filter press equipment should be selected and configured according to the actual situation. A portion of the bottom mud with a particle size close to 16 micrometers is filtered by a belt filter press after adjusting the reagent ratio and concentrating and conditioning twice in a concentration tank and a transfer conditioning tank. At the same time, reagents are added again at the mud inlet of the belt filter press to promote the mud-chemical reaction, which can achieve a dry mud moisture content of 45% to 55% and a dry mud cake thickness of 20mm to 30mm. Another portion of the bottom mud with a particle size of 14.27 microns ≤ and 16 microns is filtered by a plate and frame filter press after two thickening and conditioning processes: thickening and conditioning and intermediate conditioning. This process can achieve a solidified dry mud moisture content of 45% to 50% and a dry mud cake thickness of 35mm to 40mm. The process of thickening and conditioning microparticle sludge includes sequentially using a thickening tank, a transfer conditioning tank, and a plate and frame filter press. At the same time, the reagent ratio is adjusted to increase the thickening and flocculation time of the sludge and reagent in the thickening tank and the transfer conditioning tank, and to increase the filtration time of the plate and frame filter press. The moisture content of the dry sludge is controlled between 40% and 50%, and the sludge cake thickness can reach 30 mm. The reagents added to the concentration tank of the belt filter press are: 0.5% PAC + 0.05% PAM or 0.09% PAC + 0.15% PAM; The reagent added to the concentration tank of the plate and frame filter press is: 0.5% PAC + 0.05% PAM; The reagent ratio for multiple supply points to the belt filter press is: 10% PAC + (0.1%~0.2%) PAM; The reagent ratio for the mud transfer and conditioning tank used in conjunction with the plate and frame filter press is: 10% PAC + (0.1%~0.2%) PAM.

2. The river and lake ecological dredging construction method according to claim 1, characterized in that: The sedimented and flocculated sludge from the above-water sludge discharge is filled into geotextile bags for dewatering and consolidation. This includes filling the geotextile bags with sedimented and flocculated sludge from the above-water sludge discharge, injecting flocculants during filling, and draining the water after filling. The filling, adding flocculants, and draining steps are repeated until the geotextile bags are full and then left to stand and consolidate. The effluent is collected and transported to the primary sedimentation tank.

3. The river and lake ecological dredging construction method according to claim 2, characterized in that: Geotextile bags filled with sedimented and flocculated sludge from the surface discharge are laid along the river and lake. Once the bottom layer of geotextile bags has reached the requirements for filling and dewatering consolidation, the next layer of geotextile bags is filled and dewatered and consolidated. Before filling the next layer of tubular bags, use inelastic ropes to secure the tubular bags. The upper layer of geotextile bags should be laid between the two bottom layer geotextile bags that have been filled. After the bottom two tightly arranged geotextile bags are filled, the gap between the geotextile bags should be filled with geotextile to trap mud. The filling of the tube bags should be carried out in stages. The filling height needs to be determined by pre-work test. The bottom few tube bags should be filled at the same time and alternately. The operator should use a smooth wooden stick or similar tool to tap and vibrate the surface of the tube bags regularly to accelerate the sludge filtration and volume reduction process. A curved area is formed around the river and lake by geotextile bags, which are connected to the shore. There are also several rectangular geotextile bags laid on top of the geotextile bags. An additional layer of geotextile bags and imitation wood piles are installed on the outside of the arc-shaped area.

4. The river and lake ecological dredging construction method according to claim 2, characterized in that: Geotextile bags should be made of high-toughness geosynthetic materials, with joint strength ≥85kN / m and permeability Q. 50 ≥25L / (m 2 ·s); The chemical mixing ratio for geotextile tube bags is: 0.5% PAC + (0.1%~0.2%) PAM; Plant floating plants and emergent herbaceous plants on the silt.

5. The river and lake ecological dredging construction method according to claim 4, characterized in that: Floating plants include water hyacinth and water celery.

6. The river and lake ecological dredging construction method according to claim 4, characterized in that: Emergent aquatic herbaceous plants include reeds, water onions, and cattails.

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