River and lake bottom mud in-situ integrated purification system and construction method thereof

Abstract

The invention belongs to the field of river and lake sediment purification. The invention provides a river and lake sediment in-situ integrated purification system and a construction method thereof. The river and lake sediment in-situ integrated purification system comprises an ecological purification net, and the ecological purification net is laid on the surface layer of river and lake sediment and at the bottom sediment depth of not more than 35 cm; the ecological purification net comprises interlocking rows which are formed by connecting a plurality of sandwich structure purification units through ropes and are arranged in a matrix mode, and one row or one row of concrete pressure carriers are anchored to the row interlocking rows or the column interlocking rows at intervals of a plurality of distances through the ropes. Through construction of the sandwich structure and the chain row, multifunctional combination, land prefabrication and integrated launching arrangement are achieved, a novel river and lake bottom mud purification system construction method is provided, and the system has the advantages of being convenient to operate, stable in structure, efficient in pollutant removal and sustainable in remediation effect; the treatment and disposal cost of endogenous pollution treatment and bottom mud dredging is saved, and meanwhile the risk of secondary pollution is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of river and lake bottom mud purification, and specifically relates to an in-situ integrated river and lake bottom mud purification system and a construction method thereof. Background Art

[0002] The water environment of rivers and lakes faces a serious eutrophication problem, with nitrogen and phosphorus being the main nutritional pollutants. Sediments have important ecological and environmental functions in river and lake ecosystems, and play an important role in the adsorption and fixation of pollutants, the circulation and storage of nutrients, the habitat of microorganisms, and the regulation of physical and chemical properties. As a "warehouse" for long-term water pollution, the management and control of river and lake sediments is a prerequisite for the comprehensive management of rivers and lakes. Pollutants in sediments may be released again when water environmental conditions change, seriously threatening the water quality of overlying water bodies. Traditional dredging management methods result in a large amount of dredged silt that needs to be treated and disposed of, which not only has high treatment costs, but also requires a large amount of space for dredged soil filling, limiting the application of dredging management methods. The application of in-situ purification technology for polluted sediments in rivers and lakes, reducing the subsequent treatment and disposal of dredged silt, and reducing the cost of endogenous management of sediments in rivers and lakes are the inevitable requirements for ensuring the high-quality construction of beautiful rivers and lakes.

[0003] In-situ sediment purification technology is an eco-friendly way to conduct trenchless in-situ purification of sediment and improve habitats, while reducing the amount of excavation and subsequent treatment of polluted sediment. It can increase the environmental capacity of rivers and lakes, promote the improvement of river and lake water quality and the restoration of aquatic ecosystems. At the same time, it can effectively reduce the risks to the environment caused by the sediment disposal and landfill process, and save sediment treatment costs. Therefore, the construction of an integrated in-situ purification system for river and lake sediments is of great significance in protecting and restoring the ecological environment of water bodies, improving water quality, preventing pollution release, maintaining ecological balance, and saving costs.

[0004] Patent No. CN117383772A proposes a bionic in-situ remediation device for water body sediment, including a control system, an air intake pipe, a power unit, a first roller brush and a purification cabin, which improves the remediation efficiency while realizing in-situ remediation of sediment; however, it requires continuous energy supply, is costly and difficult to operate and maintain. Patent No. CN113501632A proposes a method for improving the bottom quality of rivers and lakes and improving the ecological environment, which effectively ensures the planting and subsequent growth of submerged plants by covering the original water area in situ after multiple repairs, but it has deficiencies in environmental impact and cost-effectiveness. Patent No. 201310501096.5 proposes an on-site remediation process for heavy metal-contaminated river and lake sediments, which is treated by chemical elution, and realizes large-scale continuous operation on the spot on the basis of ensuring the effect of heavy metal elution remediation. However, the use of chemical elution agents has adverse effects on the water ecological environment and is prone to the risk of secondary pollution. At the same time, the process has deficiencies in system stability and long-term effects. Patent No. CN117800496A proposes a river and lake sediment purification system based on gabion biological fillers, which realizes the construction of a plant buffer zone in river and lake management, and achieves water purification by paving the dredged silt in rivers and lakes. Although the system reduces organic pollutants in river water by constructing a plant buffer zone and a biological filler gabion purification system, there may be problems such as insufficient structural stability, biofilm formation and difficulty in maintenance.

[0005] Patent No. CN113636658B proposes an ecological patchwork blanket that can sustainably purify sediment and water pollutants. It mainly uses alloy fixing plates to combine sediment covering and repair layers, aerated microbial treatment layers, and plant adsorption layers to form a unitized patchwork structure with ecological purification functions. This largely overcomes the problems of the aforementioned technologies, and the invention believes that it can be sustainably used to repair river and lake water systems. However, the invention has not yet proposed its modular assembly strategy. At the same time, the energy consumption generated by the aeration device, air compressor and other equipment it uses cannot be ignored, which are important factors limiting its actual engineering application.

[0006] In order to solve these problems, the present invention proposes a construction and application method of an in-situ integrated purification system for river and lake sediments, so as to reduce the amount of sediment dredging and processing, improve the purification efficiency, achieve stable and long-term removal of pollutants, reduce costs, and reduce secondary pollution. Summary of the invention

[0007] In order to solve the above problems, the present invention provides an in-situ integrated purification system for river and lake sediments and a construction method thereof. The present invention constructs a prefabricated ecological purification net through a sandwich structure and a chain row, and lays a prefabricated ecological purification net on land on the surface of river and lake sediments, realizing multifunctional combination, onshore prefabrication, and integrated underwater laying, and provides a new method for constructing a river and lake sediment purification system, which has the advantages of convenient operation, stable structure, sustainable effect, efficient removal of pollutants, and sustainable repair effect, saving the cost of endogenous pollution control and dredging and disposal of sediments, and reducing the risk of secondary pollution.

[0008] The object of the present invention is to provide an in-situ integrated purification system for river and lake sediments, comprising an ecological purification net, which is laid on the surface of river and lake sediments, at a depth of no more than 35 cm of surface sediment; The ecological purification net includes a matrix-arranged chain row formed by connecting a number of sandwich structure purification units through ropes, and a row or a row of concrete pressure carriers are anchored by ropes to the chain row or column chain row at certain intervals; The above sandwich structure purification unit uses an ecological blanket as a skeleton, and fiber cotton is laid on the upper and lower surfaces of the ecological blanket respectively, and a slow-release oxygen material is embedded between the fiber cotton and the ecological blanket. The ecological blanket and the fiber cotton are respectively provided with a plurality of holes penetrating in the vertical direction, and fixed components are randomly inserted into the holes penetrating in the vertical direction of the purification unit; Submerged plants are planted in the holes of the purification unit, and aerobic denitrifying bacteria and polyphosphate bacteria are inoculated on the purification unit.

[0009] The ecological blanket and fiber cotton structure of the present invention are helpful to inhibit the resuspension of sediment and the re-release of sediment pollutants. Due to the good water absorption effect of the fiber cotton, it gradually sinks after contacting the sediment, driving the oxygen-releasing composite material to embed into the sediment to play a role. The slow-release oxygen material slowly releases oxygen, further promoting the growth and reproduction of aerobic denitrifying bacteria and polyphosphate bacteria on the roots of submerged plants and the fiber cotton, promoting denitrification and biological phosphorus removal. The purification system of the present invention can efficiently treat nitrogen and phosphorus nutrient pollution.

[0010] Eco-mat is made of polypropylene fiber net, geotextile and fiber interlayer, which are compacted or woven. The fiber interlayer is made of mixed fiber with coconut fiber content of not less than 50%. It can be degraded by microorganisms in 2-3 years. Polypropylene fiber net is used for hanging net laying, and geotextile is used for load bearing.

[0011] The fiber cotton has good water resistance and impact resistance, strong adsorption capacity, and good biocompatibility, which is conducive to the growth of microbial biofilm, promotes the growth of indigenous microorganisms, and enhances the self-purification ability of the ecosystem. Furthermore, the thickness of the fiber cotton laid on the upper surface of the ecological blanket is 5-10cm; the thickness of the fiber cotton laid on the lower surface of the ecological blanket is 10-30cm.

[0012] Preferably, the fiber cotton absorbs water and sinks, so that the slow-release oxygen material can be placed at the optimal placement depth, that is, near the mud-water interface, not more than 15 cm in the bottom mud depth, to ensure that the slow-release oxygen material can effectively release oxygen and avoid waste of materials, but without destroying the anaerobic environment and pH value in deep sediments, disrupting the structure of microbial communities, and can effectively increase the dissolved oxygen concentration at the mud-water interface and inhibit the release of phosphorus in sediment pollutants.

[0013] Preferably, the fiber cotton is renewable or biodegradable plant-derived fiber, such as bamboo fiber or hemp fiber. The fiber cotton laid on the upper surface of the ecological blanket is preferably hard fiber cotton with a density of 150-200 kg / m 3 The fiber cotton laid on the lower surface of the ecological blanket is preferably soft fiber cotton with a density of 50-100kg / m 3 .

[0014] The rope is preferably an environmentally friendly ramie rope or polypropylene rope with high strength, good elasticity and good biodegradability.

[0015] The slow-release oxygen material is a slow-release oxygen agent solidified by a binder such as PVA, and its main components include calcium peroxide, iron, manganese, chelating agent EDTA, etc. The slow-release oxygen material is prepared in advance and embedded between the fiber cotton and the ecological blanket or between multiple layers of fiber cotton. The calcium ions generated during the oxygen release process can remove phosphorus through adsorption and precipitation.

[0016] The amount of slow-release oxygen material added is 100-500 g / m 2 When the water body is seriously lacking in oxygen (DO<2.0mg / L), the amount of slow-release oxygen material can be increased, but not more than 1kg / m 2 .

[0017] Purification units are connected by ropes to form an interlocking ecological purification network, which can be laid and applied to the surface of sediments, thereby constructing an integrated ecological purification system of oxygen-releasing functional materials, adsorption functional materials, plants and microorganisms. By improving the redox environment at the mud-water interface, the vitality of aerobic microbial flora is restored, and the self-purification ability and resilience of the water body are enhanced. The role of the concrete pressure carrier is to ensure that the purification system sinks in time, locate the coverage range and coverage depth, and improve the structural stability and impact resistance of the purification system.

[0018] Preferably, each purification unit has a size of 40cm×40cm-60cm×60cm, a thickness of 25-45cm, a purification unit spacing of 0.4-0.6m, and a row or row of concrete ballasts anchored by ropes every 2-3m of a row or column of interlocking rows. The volume of the concrete ballast is 40-50cm × 20-25cm × 8-10cm, and a single block weighs 20-30kg.

[0019] There is a certain interval between the purification units so that the coverage area of ​​the purification units accounts for 20%-30% of the area of ​​the water body that needs to be purified, alleviating the ecological isolation of the mud-water interface caused by physical barriers, affecting material circulation, biodiversity and water fluidity.

[0020] The holes on the purification unit are positioned to ensure a 10-20 cm interval. The submerged plants of the present invention are planted in a 10 cm×10 cm-20 cm×20 cm square. The submerged plants are selected from two or more of the following: Hydrilla verticillata, Vallisneria, Ceratophyllum, Myriophyllum spicate, Potamogeton microdentata, and Waterleaf.

[0021] The present invention also aims to provide a method for constructing an in-situ integrated purification system for river and lake sediments, comprising the following steps: (1) preparing an ecological blanket and fiber cotton, and drilling holes on them respectively, embedding the above-mentioned slow-release oxygen material between the fiber cotton and the ecological blanket to form a sandwich structure purification unit, and inserting the fixing member into the hole that passes through the purification unit in the vertical direction to form a frame structure; (2) The sandwich structure purification units are connected by ropes to form a matrix-arranged chain row. The row chain row or column chain row is anchored by ropes at certain intervals to form an ecological purification network. (3) Planting submerged plants in the holes of the purification unit and inoculating aerobic denitrifying bacteria and phosphate-accumulating bacteria on the purification unit; (4) The above ecological purification net is laid on the surface of the river and lake bottom mud by underwater towing or laying by a laying ship.

[0022] The construction method of the present invention connects the purification units with ropes to form a chain row, which is convenient for subsequent engineering construction operations.

[0023] Furthermore, the sandwich structure purification unit and the concrete pressure carrier connected by ropes are prefabricated into a modular structure, and the modular structure is assembled into an ecological purification net. When in use, the modular structure is assembled to shorten the construction time of the purification system. The modular structure can be in a matrix form or other shapes.

[0024] Furthermore, anchor piles can be used to fix the ecological purification net in the underwater hard mud layer.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The construction and application methods are innovative: through sandwich structure and chain row construction, multifunctional combination, onshore prefabrication, and integrated launching are achieved, providing a new method for river and lake sediment purification; (2) Efficient pollutant removal: The purification system of the present invention is laid on the surface of river and lake sediments. The fiber cotton gradually sinks after contacting the sediments. Finally, the lower fiber cotton and the oxygen-releasing composite material are embedded in the sediments. The oxygen-releasing composite material slowly releases oxygen, promoting the growth and reproduction of aerobic denitrifying bacteria and polyphosphate bacteria on the roots of submerged plants and fiber cotton, effectively promoting denitrification and biological phosphorus removal, and efficiently removing phosphorus through the calcium ions associated with the oxygen release process. The present invention can not only efficiently treat nitrogen and phosphorus nutrient pollution, but also comprehensively deal with various pollutants such as organic matter and heavy metals, forming a long-term model of "physical and chemical property regulation-pollutant treatment and control-sediment habitat improvement-ecosystem self-purification", effectively reducing pollutants in sediments and overlying water, and reducing the risk of re-release of sediment pollutants; (3) Structural stability and biocompatibility: The sandwich structure adopted by the present invention combines adsorption materials, slow-release oxygen materials, and submerged plants, which improves the stability of the system and is not easy to loosen. At the same time, the fiber cotton has good biocompatibility, which is conducive to the growth of indigenous microorganisms, and has the advantages of stable structure and sustainable effect. (4) Cost-effectiveness and environmental friendliness: The present invention has little artificial intervention in the ecosystem, and the materials used are mostly biodegradable materials. The prefabricated river and lake bottom mud in-situ integrated purification system is laid on the surface of the river and lake bottom mud by methods such as laying boats and retreating laying, which reduces the interference with the water ecosystem, saves the cost of dredging and disposal of the bottom mud, and reduces the risk of secondary pollution; (5) After the application of an in-situ integrated purification system for river and lake sediments, most of the biodegradable materials used, such as ecological blankets and fiber cotton, are gradually biodegraded, and pollutants such as nitrogen, phosphorus, and organic matter in the surface sediments are effectively degraded in situ, gradually evolving into a restored sediment cover layer with a submerged plant coverage rate of 20-30%. It can not only buffer the re-release of pollution from the lower sediments, but also reduce interference with the structure of indigenous microbial communities, enhance the stability of the ecosystem, and improve the ecological self-purification capacity.

[0026] Therefore, the present invention adopts an innovative sandwich structure ecological purification unit and a chain-type combination and layout application mode, providing an efficient and environmentally friendly solution for the application of river and lake sediment repair agents and biological ecological purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a sandwich structure purification unit; Figure 2 This is a schematic diagram of the in-situ integrated purification system for river and lake sediments; In the figure: 1 is river and lake bottom mud; 2 is porous ecological blanket; 3 is upper fiber cotton; 4 is lower fiber cotton; 5 is fixed component; 6 is slow-release oxygen material; 7 is submerged plant; 8 is aerobic denitrifying bacteria; 9 is polyphosphate bacteria; 10 is sandwich structure purification unit; 11 is ramie rope or polypropylene rope; 12 is concrete pressure carrier; Figure 3 This is the test result of the depth of the slow-release oxygen material. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The construction method of the integrated river and lake sediment purification system is to lay an onshore prefabricated ecological purification net on the surface of river and lake sediments.

[0030] The ecological purification net is composed of multiple purification functional units linked by cross-linked ropes. Each functional unit is 40cm×40cm-60cm×60cm in size, about 25-45cm thick, and laid at an interval of 0.4-0.6m. Its purpose is to control the coverage area of ​​the functional unit (i.e. the coverage area of ​​submerged plants) to account for 20%-30% of the area of ​​the water body that needs to be purified, while alleviating the ecological isolation of the mud-water interface caused by the physical barrier, affecting material circulation, biodiversity and water fluidity. In addition, a "chain row" is formed to facilitate subsequent engineering construction operations.

[0031] The rope is preferably a ramie rope or a polypropylene rope with high strength, good elasticity and good biodegradability.

[0032] Each purification unit includes the following elements: an ecological blanket with pre-punched holes (the holes are spaced 10-20 cm apart), fiber cotton, slow-release oxygen agent, functional microorganisms, etc.

[0033] With the ecological blanket as the skeleton, 5-10cm and 10-30cm thick fiber cotton are laid on its upper and lower surfaces respectively. Pre-prepared slow-release oxygen material is inlaid between the fiber cotton and the ecological blanket to form a "sandwich structure". Fixed components are inserted at certain intervals to form a frame for the sandwich structure, which is not easy to loosen.

[0034] The ecological blanket is made of polypropylene fiber net, geotextile and fiber interlayer. Among them, the mixed fiber ecological blanket with coconut fiber content of not less than 50% in the fiber interlayer can be degraded by microorganisms in 2-3 years, the polypropylene fiber net is used for hanging net laying, and the geotextile is used for load bearing.

[0035] The fiber cotton has good water resistance and impact resistance, strong adsorption capacity, and is easy for microorganisms to form biofilms. The preferred material is renewable and biodegradable plant-based fibers, such as bamboo fibers and hemp fibers. The upper fiber cotton is preferably hard fiber cotton with a density of 150-200 kg / m 3 The lower fiber cotton is preferably soft fiber cotton with a density of 50-100kg / m 3 .

[0036] Submerged plants are planted in the fiber cotton layer in 10cm×10cm-20cm×20cm squares, and their roots are inserted into the holes. The submerged plants are selected from two or more of the following: Hydrilla verticillata, Vallisneria, Duckweed, Foxtail Algae, Potamogeton, and Water Chestnut, and are planted crosswise.

[0037] Preparation and inlay of slow-release oxygen materials: The slow-release oxygen agent is solidified with adhesives such as PVA. Its main components include calcium peroxide, iron, manganese, chelating agent EDTA, etc. It is prepared in advance and inlaid between the fiber cotton and the ecological blanket or embedded between multiple layers of fiber cotton.

[0038] The amount of slow-release oxygen material added is 100-500 g / m 2 When the water body is seriously lacking in oxygen (DO<2.0mg / L), the amount of slow-release oxygen material can be increased, but it should not exceed 1kg / m 2 .

[0039] In order to ensure that the slow-release oxygen material can effectively release oxygen and avoid waste of materials, but not destroy the anaerobic environment and pH value in deep sediments and disrupt the structure of microbial communities, its optimal placement depth should be near the mud-water interface, not exceeding 10 cm in mud depth, so as to effectively increase the dissolved oxygen concentration at the mud-water interface and inhibit the release of phosphorus in sediment pollutants.

[0040] Before being used for sediment purification, the "sandwich structure" units are inoculated with enriched aerobic denitrifying bacteria and polyphosphate bacteria.

[0041] Before laying, it is necessary to anchor a row of concrete pressure carriers with a volume of 40-50cm×20-25cm×8-10cm and a single weight of 20-30kg at the starting end of the ecological purification net every 2-3m. Its function is to ensure timely sinking, locate the coverage range, locate the coverage depth, and improve the structural stability and impact resistance of the ecological purification net.

[0042] When applied, a launching method similar to that of concrete chain row is adopted, and the prefabricated ecological purification net is laid on the surface of river and lake bottom mud by underwater dragging and laying or laying by laying boats. Furthermore, anchor piles can be used to fix the ecological purification net in the underwater hard mud layer. The ecological purification net gradually sinks due to the good water absorption of fiber cotton, driving the oxygen-releasing composite material to embed into the bottom mud and play a role. Both the ecological blanket and fiber cotton structure help to inhibit the resuspension of bottom mud and the re-release of bottom mud pollutants. At the same time, the fiber cotton has good biocompatibility and is conducive to the growth of indigenous microorganisms. The oxygen-releasing composite material slowly releases oxygen, further promoting the growth and reproduction of aerobic denitrifying bacteria and polyphosphate bacteria on the roots of submerged plants and fiber cotton, promoting denitrification and biological phosphorus removal. At the same time, the calcium ions generated in the oxygen release process can remove phosphorus through adsorption and precipitation.

[0043] Example 1 S1 Prepare an ecological blanket, cut it into a square of 40cm×40cm, and punch holes on it, with a hole interval of 10cm. In this embodiment, an ecological blanket with coconut fiber as the main material is selected. The ecological blanket is made of polypropylene fiber net, geotextile and fiber interlayer compacted. The surface layer is a polypropylene fiber net, and the fiber interlayer is between the geotextile and the polypropylene net. Among them, the mixed fiber ecological blanket with a coconut fiber content of not less than 50% in the fiber interlayer can be degraded by microorganisms in 2-3 years, the polypropylene fiber net is used for hanging net laying, and the geotextile is used for load bearing.

[0044] S2 Prepare fiber cotton, which is about 40cm×40cm square and 10cm and 20cm thick, respectively, and is placed on the upper and lower sides of the ecological blanket. In this embodiment, bamboo fiber with softness and tensile strength is selected. The fiber cotton on the upper side of the ecological blanket is preferably hard fiber cotton with a density of 150-200kg / m 3 The fiber cotton under the ecological blanket is preferably soft fiber cotton with a density of 50-100kg / m 3 . And punch holes on it with a hole interval of 10cm.

[0045] S3: preparing a slow-release oxygen material. The slow-release oxygen material can preferably be a composite material described in the invention patent "A Gradual Disintegration Slow-Release Oxygen Composite Material and Its Preparation Method" (Publication No.: CN118878066A). When preparing the material, iron, manganese, chelating agent EDTA, etc. are added as an optimization method, and the addition amount is 200g / m 2 .

[0046] S4 embeds the slow-release oxygen material between the fiber cotton and the ecological blanket to form a "sandwich structure".

[0047] S5 Insert fixed components into the four corners of the purification functional unit to form a frame structure.

[0048] S6 Connect the fixed components with ramie rope or polypropylene rope, and anchor a row of concrete pressure carriers with a volume of 40cm×20cm×10cm and a single weight of about 20kg every 2-3m to form a "chain row". The purification function units are laid at an interval of 0.4-0.6m.

[0049] S7 Plant submerged plants, such as black algae and Vallisneria, in the reserved holes on the surface of the "sandwich structure" in a grid pattern at 20 cm intervals.

[0050] S8 Inoculate enriched culture of aerobic denitrifying bacteria and polyphosphate bacteria on fiber cotton.

[0051] S9 anchors one end of the "chain row" ecological purification net on the edge of the soft row of the laying boat, and spreads the other end on the deck. The sliding plate is used to guide the laying, and the ecological purification net is laid on the surface of the river and lake bottom mud by retreating the laying boat. The fiber cotton gradually sinks after contacting the bottom mud, and finally the lower layer of fiber cotton and oxygen-releasing composite materials are embedded in the bottom mud. Sandwich structure purification unit such as Figure 1 As shown in the figure. Figure 2 As shown, the right side is the direction of water entry.

[0052] Application Examples A cylindrical bucket (11 cm in diameter and 20 cm in height) with a capacity of about 1 L was used as a reaction container, and 500 g of well-mixed fresh sediment was added to evenly cover the bottom of the bucket.

[0053] Three groups were set up. The first group was the CK group, the original sediment control group; the second group was the ORC-0 group, in which 20g of slow-release oxygen composite material ORC was added at the mud-water interface, and its main component CaO2 accounted for 50% by mass; the third group was the ORC-5 group, in which the same mass of the above-mentioned slow-release oxygen composite material ORC was added 5cm below the mud-water interface.

[0054] Siphon the aerated deionized water into the reaction vessel, cover and seal it after filling it with water, and incubate it at room temperature of 20°C. After 5 days of reaction, take the overlying water sample 1 cm above the mud-water interface, filter it and determine the concentration of ammonia nitrogen, dissolved phosphate (DIP) and total organic carbon (TOC), and use a multi-parameter analyzer to determine the pH and dissolved oxygen (DO) concentration at the mud-water interface. Figure 3 This is the test result of the depth of the slow-release oxygen material.

[0055] The DO concentration and pH value of the overlying water in the two treatment groups with ORC increased, and the oxygen release level of the ORC-0 treatment group was more significant than that of the ORC-5 treatment group. Figure 3 shown.

[0056] This shows that adding ORC to shallow sediment slows down the oxygen release process and also makes the pH of the water environment more stable. However, for nutrients in the sediment, the addition of ORC has a significant inhibitory effect on the release of ammonia nitrogen in the sediment, and the inhibitory effect of ORC-0 is more obvious. The reason is that the mud-water interface is the most active area for the interaction between the sediment and the overlying water environmental factors, and the mass transfer efficiency of dissolved oxygen in the shallow sediment is low, and the utilization of dissolved oxygen by functional microorganisms decreases. In addition, ORC can promote the conversion of phosphate from dissolved state to sediment state, and has a certain inhibitory effect on the release of soluble phosphate DIP in the sediment. Therefore, adding ORC to the mud-water interface or shallow sediment can effectively improve the dissolved oxygen level, promote the growth of denitrifying microorganisms, deposit and fix dissolved phosphorus, and enhance the ability to purify pollutants.

[0057] In the application process of the in-situ integrated purification system for river and lake sediments, it is recommended that the laying depth of the sandwich structure purification unit is preferably the mud-water interface. The slow-release oxygen material of the in-situ integrated purification system for river and lake sediments of the present invention is located near the mud-water interface, not exceeding 35 cm in the depth of the sediment, to ensure that the slow-release oxygen material effectively releases oxygen and avoids waste of materials, but does not destroy the anaerobic environment and pH value in the deep sediments, disrupt the microbial community structure, and can effectively increase the dissolved oxygen concentration at the mud-water interface and inhibit the release of phosphorus in the sediment pollutants.

[0058] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those skilled in the relevant technical field may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by the claims.

Claims

1. An in-situ integrated purification system for river and lake sediments, characterized in that: Including ecological purification nets, which are laid on the surface of river and lake sediments, no deeper than 35cm in the surface mud; The ecological purification net includes a matrix-arranged chain row formed by connecting a number of sandwich structure purification units through ropes, and a row or a row of concrete pressure carriers are anchored by ropes to the chain row or column chain row at certain intervals; The sandwich structure purification unit uses an ecological blanket as a framework, and fiber cotton is laid on the upper and lower surfaces of the ecological blanket respectively, and a slow-release oxygen material is embedded between the fiber cotton and the ecological blanket. The ecological blanket and the fiber cotton are respectively provided with a plurality of holes penetrating in the vertical direction, and fixed components are randomly inserted into the holes penetrating in the vertical direction of the purification unit; Submerged plants are planted in the holes of the purification unit, and aerobic denitrifying bacteria and polyphosphate bacteria are inoculated on the purification unit.

2. The in-situ integrated purification system for river and lake sediments according to claim 1 is characterized in that: The ecological blanket is made of polypropylene fiber net, geotextile and fiber interlayer by compaction, wherein the fiber interlayer is made of mixed fiber with coconut fiber content not less than 50%; the fiber cotton laid on the upper surface of the ecological blanket has a thickness of 5-10 cm, and the fiber cotton laid on the lower surface of the ecological blanket has a thickness of 5-30 cm.

3. The in-situ integrated purification system for river and lake sediments according to claim 2 is characterized in that: The fiber cotton laid on the surface of the ecological blanket is hard fiber cotton with a density of 150-200kg / m 3 The fiber cotton laid on the lower surface of the ecological blanket is soft fiber cotton with a density of 50-100kg / m 3 .

4. The in-situ integrated purification system for river and lake sediments according to claim 1 is characterized in that: The fiber cotton is renewable or biodegradable plant-derived fiber, and the rope is environmentally friendly ramie rope or polypropylene rope.

5. The in-situ integrated purification system for river and lake sediments according to claim 1 is characterized in that: The slow-release oxygen material is a slow-release oxygen agent formed by curing a PVA binder, and the addition amount of the slow-release oxygen material is 100-1000 g / m 2 .

6. The in-situ integrated purification system for river and lake sediments according to claim 1 is characterized in that: The purification unit has a size of 40cm×40cm-60cm×60cm, a thickness of 15-45cm, a purification unit spacing of 0.4-0.6m, and a row or a row of concrete ballasts anchored by ropes every 2-3m in a row or column of interlocking rows. The volume of the concrete ballast is 40-50cm×20-25cm×8-10cm, and a single piece weighs 20-30kg.

7. The in-situ integrated purification system for river and lake sediments according to claim 1 is characterized in that: The holes on the purification unit are spaced 10-20 cm apart, and submerged plants are planted in 10 cm×10 cm-20 cm×20 cm squares. The submerged plants are selected from at least two of the group consisting of Hydrilla verticillata, Vallisneria, Ceratophyllum, Myriophyllum spicate, Potamogeton microdentata, and Water Chestnut for cross-planting.

8. A method for constructing an in-situ integrated purification system for river and lake sediments according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) preparing an ecological blanket and fiber cotton, and drilling holes on them respectively, embedding the slow-release oxygen material between the fiber cotton and the ecological blanket to form a sandwich structure purification unit, and inserting the fixing member into the hole that passes through the purification unit in the vertical direction to form a frame structure; (2) The sandwich structure purification units are connected by ropes to form a matrix-arranged chain row. The row chain row or column chain row is anchored by ropes at certain intervals to form an ecological purification network. (3) Planting submerged plants in the holes of the purification unit and inoculating aerobic denitrifying bacteria and phosphate-accumulating bacteria on the purification unit; (4) The ecological purification net is laid on the surface of the river and lake bottom mud by underwater towing or laying by a laying ship.

9. The construction method according to claim 8, characterized in that: The sandwich structure purification units and concrete pressure carriers connected by ropes are prefabricated into a modular structure, and the modular structure is assembled into an ecological purification net.

10. The construction method according to claim 8, characterized in that: Anchor piles are used to fix the ecological purification net in the underwater hard mud layer.

Images