In-situ integrated purification system for river and lake sediment and construction method thereof

Abstract

The present application belongs to the field of river and lake sediment purification. The present application provides a kind of river and lake sediment in-situ integrated purification system and its construction method, including ecological purification net, ecological purification net is laid in the surface layer of river and lake sediment, no more than 35cm sediment depth;Ecological purification net, including the matrix arrangement of a plurality of sandwich structure purification units connected by ropes to form a chain row, every several distance row chain row or column chain row is anchored by rope with a row or a row of concrete ballast body. The present application is constructed by sandwich structure and chain row, realizes multifunctional combination, land prefabrication, integrated underwater laying, provides a new construction method of river and lake sediment purification system, has the advantages of convenient operation, stable structure, efficient removal of pollutants, sustainable repair effect, saves the treatment and disposal cost of endogenous pollution control and sediment dredging, and reduces the risk of secondary pollution.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of river and lake sediment purification, and particularly relates to a river and lake sediment in-situ integrated purification system and a construction method thereof. BACKGROUND

[0002] River and lake water environment is facing a serious eutrophication problem, and nitrogen and phosphorus are the main nutrient pollutants. Sediment plays an important ecological and environmental function in the river and lake ecosystem, and plays an important role in the adsorption and fixation of pollutants, the circulation and storage of nutrients, the habitat of microorganisms, the regulation of physical and chemical properties, etc. River and lake sediment, as a long-term pollution "warehouse" of water body, its treatment and control is a prerequisite for river and lake comprehensive regulation. Pollutants in the sediment may be released again when the water environmental conditions change, which seriously threatens the water quality of the overlying water body. Traditional dredging treatment methods result in a large amount of dredged sludge that needs to be treated and disposed, not only the treatment cost is high, but also a large amount of space is needed for dredged soil landfill, which limits the application of dredging treatment method. Application of river and lake polluted sediment in-situ purification technology can reduce the subsequent treatment and disposal amount of dredged sludge, and reduce the treatment cost of river and lake sediment endogenous, which is the inevitable requirement to protect the high-quality construction of beautiful rivers and lakes.

[0003] In-situ sediment purification technology is to improve the river and lake water environmental capacity, promote the improvement of river and lake water quality and the restoration of water ecological system through ecological friendly way under the premise of reducing the amount of dredging and subsequent treatment and disposal of polluted sediment, non-excavation in-situ purification and habitat improvement of sediment. At the same time, it can effectively reduce the risk of environment generated by the process of sediment disposal landfill, and save the cost of sediment treatment. Therefore, constructing river and lake sediment in-situ integrated purification system has important significance for protecting and restoring water ecological environment, improving water quality, preventing pollution release, maintaining ecological balance and saving cost, etc.

[0004] Patent No. CN117383772A proposes a water body sediment biomimetic in-situ remediation device, which includes a control system, an air inlet pipe, a power unit, a first roller brush and a purification cabin. It improves the remediation efficiency while realizing in-situ remediation of sediment. However, it requires continuous energy supply, has high cost and difficult operation and maintenance. Patent No. CN113501632A proposes a river and lake bottom improvement and ecological environment improvement method, which covers the original water area after multiple repairs, effectively ensures the planting and subsequent growth of submerged plants, but has deficiencies in environmental impact and cost-effectiveness. Patent No. 201310501096.5 proposes a heavy metal contaminated river and lake sediment in-situ remediation process, which uses chemical elution to treat and ensure the effect of heavy metal elution remediation, and realizes large-scale continuous operation on site. However, the use of chemical elution reagent has adverse effects on the aquatic environment and may cause secondary pollution, and the process has deficiencies in system stability and long-term effect. Patent No. CN117800496A proposes a river and lake sediment purification system based on stone cage biological filler, which realizes the construction of plant buffer zone in river and lake management, and realizes water quality purification by piling up dredged sludge in the river and lake. Although this system reduces organic pollutants in river water by constructing a plant buffer zone and a biological filler stone cage purification system, it may have problems of insufficient structural stability, difficulty in biofilm formation and maintenance.

[0005] Patent No. CN113636658B proposes an ecological splicing blanket that can sustainably purify sediment and water pollutants, which mainly uses alloy fixing pieces to combine a sediment covering repair layer, an aeration microbial treatment layer and a plant adsorption layer to form a unit type splicing structure with ecological purification function. This largely overcomes the problems of the foregoing technologies, and the invention believes that it can be applied to repair river and lake water systems. However, the invention has not proposed its modular assembly strategy, and the energy consumption of the aeration device and air compressor used in the invention cannot be ignored, which are important factors limiting its practical engineering application.

[0006] To solve these problems, the present invention proposes a construction and application method of a river and lake sediment in-situ integrated purification system to reduce sediment dredging treatment volume, improve purification efficiency, realize stable and long-term pollutant removal, reduce cost and reduce secondary pollution. SUMMARY

[0007] In order to solve the above problems, the application provides a river and lake sediment in-situ integrated purification system and a construction method thereof. The prefabricated ecological purification net is constructed through a sandwich structure and a chain row, the ecological purification net is formed by laying the prefabricated ecological purification net on the surface layer of the river and lake sediments, multifunctional combination, prefabrication on land, integrated underwater laying are achieved, a new construction method of the river and lake sediment purification system is provided, the method has the advantages of convenient operation, stable structure, sustainable effect, efficient removal of pollutants and sustainable repair effect, the cost of endogenous pollution treatment and dredging treatment and disposal of the sediment is saved, and the secondary pollution risk is reduced.

[0008] The application aims to provide a river and lake sediment in-situ integrated purification system, which comprises an ecological purification net, the ecological purification net is laid on the surface layer of the river and lake sediments, and the depth of the surface layer of the sediment is not more than 35 cm.

[0009] The ecological purification net comprises a matrix arranged chain row formed by connecting a plurality of sandwich structure purification units through a rope, and a row or a row of concrete ballast bodies are anchored through the rope at every several distances of the row chain row or the column chain row.

[0010] The above-mentioned sandwich structure purification unit takes the ecological blanket as a framework, fiber cotton is laid on the upper and lower surfaces of the ecological blanket respectively, slow-release oxygen materials are inlaid 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 a fixing member is randomly inserted into the hole penetrating in the vertical direction of the purification unit.

[0011] The hole of the purification unit is planted with submerged plants, and the purification unit is inoculated with aerobic denitrifying bacteria and phosphorus accumulating bacteria.

[0012] The structure of the ecological blanket and the fiber cotton of the application is helpful to inhibit the resuspension of the sediment and the re-release of the sediment pollutants. The fiber cotton gradually sinks after contacting the sediment due to the good water absorption of the fiber cotton, drives the release of the oxygen composite material into the sediment to play a role, the slow-release oxygen material slowly releases oxygen, further promotes the growth and reproduction of the aerobic denitrifying bacteria and the phosphorus accumulating bacteria on the root system of the submerged plants and the fiber cotton, promotes denitrification and biological phosphorus removal, and the purification system of the application can efficiently treat nitrogen and phosphorus nutrient salt pollution.

[0013] The ecological blanket adopts a polypropylene fiber net, a geotextile and a fiber sandwich layer, and is compacted or sewn to be made, wherein the fiber sandwich layer is made of mixed fibers with a coconut fiber content of not less than 50%. The ecological blanket can be degraded by microorganisms for 2-3 years. The polypropylene fiber net is used for hanging net laying, and the geotextile is used for load bearing.

[0014] The fiber cotton has good water resistance and impact resistance, strong adsorption capacity, and good biocompatibility, which helps the growth of microbial biofilm and promotes the growth of indigenous microorganisms, and enhances the self-purification ability of the ecological system. Further, the thickness of the fiber cotton laid on the upper surface of the ecological blanket is 5-10 cm; and the thickness of the fiber cotton laid on the lower surface of the ecological blanket is 10-30 cm.

[0015] Preferably, the water absorption and sinking of the fiber cotton can make the slow-release oxygen material be located at the optimal placement depth, i.e. near the mud-water interface, not more than 15 cm deep in the sediment, to ensure that the slow-release oxygen material effectively releases oxygen, avoids waste of the material, but does not destroy the anaerobic environment and pH value in the deep sediment, disturbs the microbial community structure, can effectively increase the dissolved oxygen concentration of the mud-water interface, and inhibit the release of phosphorus in the sediment pollutants.

[0016] Preferably, the fiber cotton is a renewable or biodegradable plant fiber. For example, 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 ; and the fiber cotton laid on the lower surface of the ecological blanket is preferably soft fiber cotton, with a density of 50-100 kg / m 3 .

[0017] The rope is preferably an environmentally friendly ramie rope or polypropylene rope with high strength, good elasticity, and good biodegradability.

[0018] The slow-release oxygen material is a slow-release oxygen agent formed by using a binder such as PVA to solidify, and the main components include calcium peroxide, iron, manganese, chelating agent EDTA, etc. The slow-release oxygen material is prepared in advance and inlaid between the fiber cotton and the ecological blanket or embedded between multiple layers of fiber cotton, and the calcium ions generated in the oxygen release process can remove phosphorus through adsorption and precipitation.

[0019] The addition amount of the slow-release oxygen material is 100-500 g / m 2 , and when the water body is in serious anoxia (DO<2.0 mg / L), the addition amount of the slow-release oxygen material can be increased, but not more than 1 kg / m 2 .

[0020] The purification units are connected by ropes to form a chain row type ecological purification net, which is applied to the surface layer of the sediment in a row, so as to construct an ecological purification system integrating oxygen release function material-adsorption function material-plant-microorganism, improve the redox environment of the mud-water interface, restore the activity of aerobic microbial flora, and enhance the self-purification ability and recovery ability of the water body. The concrete ballast body can ensure that the purification system is timely submerged, positioned and covered in a range and depth, and improve the structural stability and impact resistance of the purification system.

[0021] Preferably, each purification unit has a size of 40cm x 40cm-60cm x 60cm, a thickness of 25-45cm, and a spacing distance of 0.4-0.6m, and every 2-3m row or column of the chain row is anchored by a row or a column of concrete ballast bodies through a rope, and the concrete ballast body has a volume of 40-50cm x 20-25cm x 8-10cm and a single weight of 20-30kg.

[0022] The purification units are spaced apart to cover an area of 20%-30% of the water body to be purified, thereby alleviating the ecological isolation of the mud-water interface caused by the physical barrier and affecting the material circulation, biological diversity and water flow.

[0023] The holes on the purification unit are spaced apart by 10-20cm. The submerged plants are planted in a 10cm x 10cm-20cm x 20cm grid. The submerged plants are selected from two or more of Hydrilla verticillata, Vallisneria spiralis, Ceratophyllum demersum, Myriophyllum spicatum, Potamogeton pectinatus and Stuckenia filiformis.

[0024] The present application also provides a construction method of the river and lake sediment in-situ integrated purification system, which comprises the following steps:

[0025] (1) preparing an ecological blanket and fiber cotton, punching holes in them respectively, embedding the slow-release oxygen material between the fiber cotton and the ecological blanket to form a sandwich structure purification unit, inserting a fixing member into the vertical hole of the purification unit to form a frame structure;

[0026] (2) connecting the sandwich structure purification units by a rope to form a matrix arrangement of chain rows, and every several distances of the row or column of the chain row is anchored by a row or a column of concrete ballast bodies through a rope to form an ecological purification net;

[0027] (3) planting submerged plants in the holes of the purification unit, inoculating aerobic denitrifying bacteria and phosphorus accumulating bacteria on the purification unit;

[0028] (4) using an underwater drag laying method or a laying ship to lay the ecological purification net on the surface of the river and lake sediment.

[0029] The rope connection of the purification units in the construction method forms a chain row, which is convenient for subsequent engineering operation.

[0030] Further, the sandwich structure purification units and the concrete ballast bodies connected by the rope are prefabricated into a modular structure, and the modular structure is assembled into an ecological purification net. The modular structure is assembled during use to shorten the construction time of the purification system. The modular structure can be in a matrix form or other shapes.

[0031] Further, the ecological purification net can be fixed in the underwater hard mud layer by using anchor piles.

[0032] Compared with the prior art, the application has the beneficial effects:

[0033] (1) The construction and application method is innovative: through the construction of sandwich structure and chain row, multifunctional combination, land precast and integrated underwater laying are realized, and a new purification method for river and lake sediment is provided.

[0034] (2) Efficient pollutant removal: the purification system of the application is laid on the surface of river and lake sediment, the fiber cotton contacts the sediment and gradually sinks, and finally the lower fiber cotton and oxygen release composite material are embedded in the sediment, the oxygen release composite material slowly releases oxygen, promotes the growth and reproduction of the root system of submerged plants, and the growth and reproduction of aerobic denitrifying bacteria and phosphorus accumulating bacteria on the fiber cotton, effectively promotes denitrification and biological phosphorus removal, and the calcium ion associated with the oxygen release process efficiently removes phosphorus, the application can not only efficiently treat nitrogen and phosphorus nutrient salt pollution, but also comprehensively deal with various pollutants such as organic matter and heavy metals, form a long-term mode of "physical and chemical property regulation-pollutant treatment and control-sediment habitat improvement-ecosystem self-purification", effectively reduce the pollutants in the sediment and overlying water, and reduce the re-release risk of sediment pollutants.

[0035] (3) Structural stability and biocompatibility: the sandwich structure used in the application combines the adsorption material, the slow-release oxygen material and the submerged plant, improves the stability of the system and is not easy to loosen, and the fiber cotton has good biocompatibility, which is helpful to the growth of indigenous microorganisms, has the advantages of structural stability and sustainable effect.

[0036] (4) Cost-effectiveness and environmental friendliness: the application has less artificial intervention to the ecosystem, the materials used are mostly biodegradable materials, the laying ship retreats and lays the prefabricated river and lake sediment integrated purification system on the surface of the river and lake sediment, reduces the disturbance to the aquatic ecosystem, saves the dredging treatment and disposal cost of the sediment, and reduces the secondary pollution risk.

[0037] (5) After the application of the river and lake sediment in-situ integrated purification system, most of the biodegradable materials such as ecological blanket and fiber cotton are gradually biodegraded, the pollutants such as nitrogen, phosphorus and organic matter in the surface sediment are effectively degraded in-situ, and a repaired sediment covering layer with a submerged plant coverage of 20-30% is gradually evolved, which can not only buffer the pollution re-release of the lower sediment, but also reduce the disturbance to the indigenous microbial community structure, enhance the stability of the ecosystem and improve the ecological self-purification ability.

[0038] Therefore, the application adopts innovative sandwich structure ecological purification unit and combination and paving application mode of chain row, and provides an efficient and environment-friendly solution for river and lake sediment remediation agent application and biological ecological purification. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a schematic diagram of the sandwich structure purification unit.

[0040] Figure 2 It is a schematic diagram of the in-situ integrated purification system for river and lake sediment.

[0041] In the figure: 1 is river and lake sediment; 2 is porous ecological blanket; 3 is upper layer of fiber cotton; 4 is lower layer of fiber cotton; 5 is fixing member; 6 is slow-release oxygen material; 7 is submerged plant; 8 is aerobic denitrifying bacteria; 9 is phosphorus accumulating bacteria; 10 is sandwich structure purification unit; 11 is ramie rope or polypropylene rope; 12 is concrete ballast.

[0042] Figure 3 It is the test result of the position depth of the slow-release oxygen material. DETAILED DESCRIPTION

[0043] The technical solutions of the application will be described clearly and completely below in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0044] The construction method of the integrated river and lake sediment purification system is to lay the ecological purification net pre-prepared on land on the surface layer of river and lake sediments.

[0045] The ecological purification net is composed of a plurality of purification function units linked by rope cross connection, and each function unit has a size of 40cm×40cm-60cm×60cm, a thickness of about 25-45cm, and a laying interval distance of 0.4-0.6m. The purpose is to control the coverage area of the function unit (i.e. the coverage area of the submerged plant) to account for 20%-30% of the area of the water body to be purified, and to alleviate the ecological isolation of the mud-water interface caused by the physical barrier, the influence of material circulation, biological diversity and water flow, etc. In addition, the chain row is formed, which facilitates subsequent engineering construction operation.

[0046] The rope is preferably ramie rope or polypropylene rope with high strength, good elasticity and good biodegradability.

[0047] Each purification unit includes the following elements: ecological blanket with holes punched in advance (hole position guaranteed 10-20cm interval), fiber cotton, slow-release oxygen agent, functional microorganisms, etc.

[0048] The ecological blanket is used as a framework, and 5-10 cm and 10-30 cm thick fiber cotton is laid on the upper and lower surfaces of the ecological blanket respectively. The pre-prepared slow-release oxygen material is inlaid between the fiber cotton and the ecological blanket to form a "sandwich structure". The slow-release oxygen material is inserted into the fixed component at a certain interval to form a frame so that the sandwich structure is not easy to be loose.

[0049] The ecological blanket is made of polypropylene fiber net, geotextile and fiber sandwich. The mixed fiber ecological blanket with the content of coconut fiber in the fiber sandwich being not less than 50% 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.

[0050] The fiber cotton has good water resistance and impact resistance, strong adsorption capacity and easy microbial film formation. The preferred material of the fiber cotton is renewable and biodegradable plant fiber such as bamboo fiber and hemp fiber. The upper fiber cotton is preferably hard fiber cotton with a density of 150-200 kg / m 3 , and the lower fiber cotton is preferably soft fiber cotton with a density of 50-100 kg / m 3 .

[0051] The submerged plants are planted in the fiber cotton layer at every 10 cm x 10 cm-20 cm x 20 cm square, and the root systems are inserted into the punched holes. Two or more of the submerged plants selected from the group consisting of Hydrilla verticillata, Vallisneria spiralis, Ceratophyllum demersum, Scirpus fluviatilis, Potamogeton pectinatus and Elodea canadensis are cross-planted.

[0052] Preparation and inlay of slow-release oxygen material: the slow-release oxygen agent is solidified and formed using a binder such as PVA, and the main components include calcium peroxide, iron, manganese, chelating agent EDTA, etc. The slow-release oxygen material is pre-prepared and inlaid between the fiber cotton and the ecological blanket or embedded between the multiple fiber cotton layers.

[0053] The addition amount of the slow-release oxygen material is 100-500 g / m 2 . When the water body is seriously oxygen-deficient with DO < 2.0 mg / L, the addition amount of the slow-release oxygen material can be increased, but should not exceed 1 kg / m 2 .

[0054] In order to ensure that the slow-release oxygen material effectively releases oxygen and avoid waste of the material, but also not to destroy the anaerobic environment and pH value in the deep sediment and disturb the microbial community structure, the best placement depth of the slow-release oxygen material should be near the mud-water interface, not more than 10 cm deep in the sediment, so as to effectively increase the dissolved oxygen concentration of the mud-water interface and inhibit the release of phosphorus in the sediment pollutants.

[0055] Before being applied to the purification of the sediment, the "sandwich structure" unit is inoculated with the enriched and cultured aerobic denitrifying bacteria and phosphorus accumulating bacteria respectively.

[0056] Before laying, a row of concrete ballast with a volume of 40-50 cm x 20-25 cm x 8-10 cm and a single block weight of 20-30 kg should be anchored every 2-3 m at the starting end of the ecological purification net. Its role is to ensure timely sinking, positioning coverage, positioning coverage depth, and improving the structural stability and impact resistance of the ecological purification net.

[0057] In application, a method similar to the continuous chain of concrete is used to lay the ecological purification net on the surface of the river and lake sediment. Further, an anchor pile can be used to fix the ecological purification net in the hard mud layer underwater. The ecological purification net gradually sinks due to the good water absorption of the fiber cotton, driving the oxygen-releasing composite material to embed in the sediment to play a role. The ecological blanket and fiber cotton structure both help to inhibit sediment resuspension and sediment pollutant release. At the same time, the fiber cotton has good biocompatibility, which helps the growth of indigenous microorganisms. The slow release of oxygen by the oxygen-releasing composite material further promotes the growth and reproduction of aerobic denitrifying bacteria and phosphorus-accumulating bacteria on the roots of submerged plants and fiber cotton, promoting denitrification and biological phosphorus removal. At the same time, the calcium ions generated during the oxygen release process can remove phosphorus through adsorption and precipitation.

[0058] Example 1

[0059] S1 Prepare the ecological blanket, cut it into a square with a size of 40 cm x 40 cm, and punch holes on it with a hole spacing of 10 cm. In this embodiment, the ecological blanket with coconut fiber as the main material is selected. The ecological blanket is made of polypropylene fiber mesh, geotextile, and fiber interlayer. The surface layer is polypropylene fiber mesh, and the fiber interlayer is between the geotextile and the polypropylene mesh. Among them, the coconut fiber content in the fiber interlayer of the mixed fiber ecological blanket is not less than 50%, which can be degraded by microorganisms in 2-3 years, the polypropylene fiber mesh is used for net laying, and the geotextile is used for load bearing.

[0060] S2 Prepare the fiber cotton, which is about 40 cm x 40 cm in size and 10 cm and 20 cm in thickness, respectively, on the top and bottom of the ecological blanket. In this embodiment, bamboo fiber with softness and tensile strength is selected. The fiber cotton on the top of the ecological blanket is preferably hard fiber cotton with a density of 150-200 kg / m 3 , and the fiber cotton on the bottom of the ecological blanket is preferably soft fiber cotton with a density of 50-100 kg / m 3 . And punch holes on it with a hole spacing of 10 cm.

[0061] S3 Prepare the slow-release oxygen material. The slow-release oxygen material can be preferably the composite material described in the invention patent “A gradual disintegration slow-release oxygen composite material and its preparation method” (publication number: CN118878066A). Iron, manganese, and chelating agent EDTA can be added as optimization methods during material preparation, with an addition amount of 200 g / m 2.

[0062] S4 Inlaying the slow-release oxygen material between the fiber cotton and the ecological carpet to form a "sandwich structure".

[0063] S5 Inserting the fixing members at the four corners of the purification functional unit to form a frame structure.

[0064] S6 Connecting the fixing members by ramie ropes or polypropylene ropes, and anchoring a row of concrete ballast bodies with a volume of 40 cm x 20 cm x 10 cm and a single weight of about 20 kg every 2-3 m to form a "chain row". The purification functional units are laid with a spacing distance of 0.4-0.6 m.

[0065] S7 Planting submerged plants such as black algae and Vallisneria in the reserved holes on the surface of the "sandwich structure" with a 20 cm interval grid planting.

[0066] S8 Inoculating the fiber cotton with the enriched aerobic denitrifying bacteria and phosphorus accumulating bacteria.

[0067] S9 Anchoring one end of the "chain row" type ecological purification net at the edge of the soft mattress of the laying boat, and laying the other end on the deck. The ecological purification net is laid on the surface of the river and lake sediment by the method of withdrawing the mattress of the laying boat, and the fiber cotton gradually sinks after contacting the sediment, and finally the lower fiber cotton and the oxygen release composite material are embedded in the sediment. The "sandwich structure" purification unit is shown in Figure 1 . The "chain row" type river and lake sediment in-situ integrated purification system is shown in Figure 2 . The right side is the water inlet laying direction.

[0068] Application Example

[0069] A cylindrical water bucket with a volume of about 1 L (diameter 11 cm, height 20 cm) is used as a reaction container, and 500 g of mixed fresh sediment is added to uniformly cover the bottom of the bucket.

[0070] Three groups are set up. The first group is the CK group, the original sediment control group; the second group is the ORC-0 group, and 20 g of slow-release oxygen composite material ORC is added at the interface of the sediment and water, and the main component CaO2 accounts for 50% of the mass ratio; the third group is the ORC-5 group, and the same amount of slow-release oxygen composite material ORC is added at the position 5 cm below the interface of the sediment and water.

[0071] After aeration, the deionized water is siphoned into the reaction container, and after the water is filled, it is sealed with a lid. Cultivate at room temperature 20℃. After 5 days of reaction, take the overlying water sample 1 cm above the sediment-water interface, filter, and measure the ammonia nitrogen, dissolved phosphate (DIP) concentration and total organic carbon (TOC), and use a multi-parameter analyzer to measure the pH and dissolved oxygen (DO) concentration at the sediment-water interface, Figure 3The depth of the slow-release oxygen material position is tested.

[0072] The DO concentration and pH value in the overlying water of the two treatment groups with ORC addition increase, and the oxygen release level of the ORC-0 treatment group is more significant than that of the ORC-5 treatment group, as shown in the following table. Figure 3

[0073] This shows that the addition of ORC in the shallow sediment slows down the oxygen release process and also stabilizes the pH of the water environment. 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 sediment-water interface is the most active area of interaction between sediment and overlying water environmental factors, and the mass transfer efficiency of dissolved oxygen in shallow sediment is low, and the availability of dissolved oxygen for functional microorganisms decreases. In addition, ORC can promote the transformation of phosphate from dissolved state to sediment state, and has a certain inhibitory effect on the release of dissolved phosphorus in sediment. Therefore, the addition of ORC in the sediment-water interface or in the shallow sediment can effectively improve the dissolved oxygen level, promote the growth of denitrifying microorganisms, sediment fixation of dissolved phosphorus, and improve the pollutant purification capacity.

[0074] In the application process of the in-situ integrated purification system for river and lake sediment, it is recommended to preferentially lay the depth of the sandwich structure purification unit at the sediment-water interface. The slow-release oxygen material of the in-situ integrated purification system for river and lake sediment of the present application is located near the sediment-water interface, not more than 35 cm deep in the sediment, to ensure that the slow-release oxygen material effectively releases oxygen, avoids waste of materials, but does not disturb the anaerobic environment and pH value in the deep sediment, and does not disturb the microbial community structure, can effectively increase the dissolved oxygen concentration of the sediment-water interface, and inhibit the release of phosphorus in the sediment pollutants.

[0075] The above examples are only for illustrating the present application, and are not limited to the present application. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the present application. Therefore, all equivalent technical solutions should belong to the scope of the present application, which is defined by the claims.​

Claims

1. An integrated in-situ purification system for river and lake bottom sediment, characterized in that, This includes ecological purification nets, which are laid on the surface of river and lake sediments, at a depth of no more than 35cm in the bottom mud. The ecological purification network consists of a matrix arrangement of several sandwich-structure purification units connected by ropes. The sandwich structure purification unit uses an ecological blanket as its skeleton. Fiber cotton is laid on the upper and lower surfaces of the ecological blanket, and 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 several vertically penetrating holes. Fixing components are randomly inserted into the vertically penetrating holes of the purification unit. Submerged plants are planted in the holes of the purification unit, and aerobic denitrifying bacteria and polyphosphate-accumulating bacteria are inoculated on the purification unit. The thickness of the fiber cotton laid on the upper surface of the ecological blanket is 5-10cm, and the thickness of the fiber cotton laid on the lower surface of the ecological blanket is 5-30cm. The fiber cotton laid on the surface of the ecological blanket is hard fiber cotton with a density of 150-200 kg / m³. 3 The fiber cotton laid on the underside of the ecological blanket is soft fiber cotton with a density of 50-100 kg / m³. 3 ; The purification unit is 40cm×40cm-60cm×60cm in size and 15-45cm in thickness. The spacing between the purification units is 0.4-0.6m. Every 2-3m, a row or column of interlocking concrete pressure carriers are anchored by ropes. The concrete pressure carriers have a volume of 40-50cm×20-25cm×8-10cm and a weight of 20-30kg per piece. The ecological blanket is made of polypropylene fiber mesh, geotextile and fiber interlayer compacted together, wherein the fiber interlayer is made of mixed fibers with a coconut fiber content of not less than 50%. The fiber cotton is a renewable or biodegradable plant-derived fiber, and the rope is an environmentally friendly ramie rope or polypropylene rope.

2. The in-situ integrated purification system for river and lake bottom sediments according to claim 1, characterized in that, The slow-release oxygen material is a slow-release oxygen agent cured with PVA binder, and the addition amount of the slow-release oxygen material is 100-1000 g / m³. 2 .

3. The in-situ integrated purification system for river and lake bottom sediments according to claim 1, characterized in that, The holes on the purification unit are spaced 10-20cm apart, and the submerged plants are planted in squares of 10cm×10cm-20cm×20cm. At least two of the following submerged plants are selected from Hydrilla verticillata, Vallisneria natans, Ceratophyllum demersum, Myriophyllum spicatum, Potamogeton pectinatus, and Aquatic Plants and planted alternately.

4. A method for constructing an integrated in-situ purification system for river and lake sediments as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Prepare an ecological blanket and fiber cotton, and punch holes in them respectively. Embed the slow-release oxygen material between the fiber cotton and the ecological blanket to form a sandwich structure purification unit. Insert the fixing component into the vertical through hole of the purification unit to form a frame structure. (2) The sandwich structure purification units are connected by ropes to form a matrix of interlocking rows. Every certain distance, the row or column interlocking rows are anchored to a row or column of concrete pressure carriers by ropes to form an ecological purification network. (3) Plant submerged plants in the holes of the purification unit and inoculate aerobic denitrifying bacteria and polyphosphate-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 by laying boat.

5. The construction method according to claim 4, characterized in that, The sandwich-structure purification units connected by ropes and the concrete pressure carrier are prefabricated into modular structures, and the modular structures are assembled into an ecological purification net.

6. The construction method according to claim 4, characterized in that, The ecological purification net is fixed in the underwater hard mud layer using anchor piles.

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