A portable and modular lake pollution remediation device and its application

Abstract

The present invention discloses a portable and modular lake and bay pollution remediation device, comprising a number of remediation modules containing a cathode and an aquatic plant root control system. The aquatic plant root control system comprises an outer shell, an anode, a root control plate and a matrix. The cathode floats on the overlying water body. The outer shell is a cylindrical shell with upper and lower openings. The inner shell contains a matrix, a root control plate and an anode from top to bottom. The aquatic plants are planted in the matrix. The outer shell is provided with pores. The root control plate is a mesh plate that matches the inner diameter of the outer shell. Under the action of the root control plate, the plant roots can penetrate into the polluted sediments, and at the same time, carry the activated carbon with conductive properties in the matrix and flexibly disperse into the polluted sediments, thereby enhancing the conductive properties inside the sediments and improving the bioelectric current remediation performance of the system. Under the action of the root control plate, independent, organic monomers with strong remediation performance are formed. These monomers form a conductive network inside the sediments in a parallel manner, thereby enhancing the bioelectric current remediation performance of the complex pollution in the lake and bay.

Description

Technical Field

[0001] The present invention belongs to the technical field of ecological restoration of water environment, and specifically relates to a biological-ecological integrated device and method for strengthening the restoration of complex pollution in lakes and bays, and especially to a portable and modular device and method for strengthening the restoration of complex pollution in lakes and bays using bioelectric current. Background Art

[0002] At present, the control of complex pollution in water sediments mainly adopts dredging, in-situ covering and enhanced bioremediation. Although dredging is effective quickly, it is costly and there are secondary pollution problems such as the subsequent off-site disposal of contaminated sediments. In-situ covering refers to the placement of inert or active materials to cover the surface of contaminated sediments, which can quickly control pollution, but there is a risk that sediment pollutants will be released into the water body as environmental conditions change. Although the cost of using electron acceptors such as iron oxides and nitrates to enhance bioremediation is low, the addition of inorganic salts will have a negative impact on the aquatic ecosystem. At present, the technologies and processes for enhancing the remediation of pollutants in water bodies using bioelectric currents are mainly: microbial electrochemical processes and plant-microbial fuel cell coupling processes. As a new and efficient in-situ bioremediation technology and process for pollutants, the plant-microbial fuel cell coupling process has broad application prospects. However, the existing plant-microorganism fuel cell coupling process has the following defects in in-situ applications: (1) For microbial electrochemical processes or coupling processes with a dual-chamber structure, expensive proton exchange membranes are required as diaphragms, which do not have practical value and are not suitable for large-scale field applications; (2) For air cathode single-chamber microbial electrochemical processes or biocathode microbial electrochemical processes, there are relatively few reports on their combination with plant remediation technology; however, coupling with ecological floating beds also has the disadvantages of limited remediation effects, a single plant type, and the inability to effectively bioremediate deep contaminated sediments; (3) The existing process structure has the disadvantages of poor portability and difficulty in large-scale application in lake bays. Summary of the invention

[0003] In view of the defects or shortcomings of the prior art, the purpose of the present invention is to provide a portable, scalable, modular plant-microorganism fuel cell device and a method for enhancing the restoration of complex pollution in lakes and bays using bioelectric current. The biological-ecological integrated device can enhance the restoration of complex pollution in lakes and bays, and solve the problems that the existing plant-microorganism fuel cell devices cannot efficiently repair contaminated sediments, cannot be transplanted, and cannot be applied on a large scale to lake and bay sites.

[0004] To achieve the above object, the present invention is specifically implemented through the following technical solutions:

[0005] A portable and modular lake pollution remediation device, comprising a plurality of remediation modules,

[0006] The restoration module includes a cathode and an aquatic plant root control system at least partially disposed in the sediment.

[0007] The aquatic plant root control system includes an outer shell, an anode, a root control plate and a matrix. The cathode is connected to the anode through an external circuit. The cathode floats on the overlying water body. The outer shell is a cylinder with upper and lower openings. The inner shell contains the matrix, the root control plate and the anode from top to bottom. Aquatic plants are planted in the matrix. The outer shell is provided with pores. The root control plate is a mesh plate that matches the inner diameter of the outer shell. The root control plate is arranged in the sediment below.

[0008] Furthermore, the shell is cylindrical, and its diameter is preferably 30 cm.

[0009] Furthermore, the surface of the shell has concave and convex parts, the concave and convex parts are arranged alternately in a corrugated shape, the stomata are arranged at the top of the convex parts, and the number of stomata is preferably 190. This structure is helpful for root growth and root control of aquatic plants and large-scale transplantation.

[0010] Furthermore, the anode is carbon felt or graphite felt, preferably with a thickness of 2 to 3 mm and a height of 8 cm.

[0011] Furthermore, the anode surrounds the bottom of the aquatic plant root control system.

[0012] Furthermore, the cathode is carbon felt or graphite felt, preferably with a thickness of 2 to 3 mm, a length of 86 cm, and a width of 8 cm.

[0013] Furthermore, the cathode floats on the water surface using a floating rod.

[0014] Furthermore, the aquatic plants are submerged plants or emergent plants.

[0015] Furthermore, the submerged plant is foxtail algae or Vallisneria, and the emergent plant is calamus or reed.

[0016] Furthermore, the mesh spaces of the root control plate are 1 cm squares.

[0017] Furthermore, the matrix is ​​conductive coconut shell activated carbon.

[0018] Furthermore, the coconut shell activated carbon has a conductivity of 50-100 W / cm.

[0019] Furthermore, the thickness of the substrate in each of the plant root control systems is 3 to 5 cm.

[0020] Furthermore, the amount of substrate laid in each plant root control system is 1.5-3.5 kg / m2 That is, based on the area of ​​the root control board, 1.5-3.5 kg of substrate is laid on each square meter of the root control board.

[0021] Furthermore, the repair modules are connected in parallel.

[0022] The present invention also provides the use of the above-mentioned portable and modular lake and bay pollution restoration device in the restoration of lake and bay complex pollution.

[0023] The portable and modular lake and bay pollution remediation device provided by the present invention can allow the roots of aquatic plants to penetrate deep into the polluted sediments under the action of the root control plate, while carrying a matrix with conductive properties and flexibly dispersing it into the polluted sediments to form a carbon-based complex, thereby enhancing the conductive properties inside the sediments and improving the system's biocurrent remediation performance. The root control plate in the system can effectively coordinate the distance between the anode and the plant roots, avoiding direct contact between the plant roots and the anode, thereby reducing the impact of oxygen secretion by the aquatic plant roots on the anaerobic decomposition of organic matter in the anode area. After the lake and bay pollutants are effectively removed, they can be quickly transplanted and modularly applied to other polluted areas.

[0024] The complex pollution in the surface sediments of the lake bay can be efficiently repaired by the bioelectric current formed by the anode of the aquatic plant root control system; and for the complex pollution in the deep sediments of the lake bay, the aquatic plant root control system can be used to effectively colonize the roots of aquatic plants in the deep polluted sediments, and the aquatic plant roots can enrich, extract and purify the pollutants to improve the removal performance of pollutants. At the same time, under the action of the secretions of the aquatic plant roots, the bioavailability of pollutants in the sediment can be improved, and the bioelectric remediation performance of pollutants can be enhanced. The carbon-based complex can not only efficiently lock the complex pollutants in the water body, but also promote the growth of the aquatic plant root system.

[0025] Positive effects of adopting the above technical solution: The present invention integrates the three technologies of sediment microbial fuel cell technology, aquatic plant restoration technology and activated carbon covering into one by using an aquatic plant root control system. The use of the root control plate in the system effectively couples the sediment microbial fuel cell technology with the aquatic plant restoration technology, so that the aquatic plant root system and the anode of the microbial fuel cell can be effectively coupled, reducing the influence of the aquatic plant root system's oxygen secretion on the anaerobic decomposition performance of organic matter in the anode area. The peat in the carbon-based complex in the system efficiently locks the complex pollutants, which are decomposed and transformed by microorganisms in the sediment at the anode. At the same time, the roots of aquatic plants penetrate into the deep sediments under the action of the root control plate to enrich, extract and purify the pollutants buried in the deep sediments. The growth of the developed plant root system formed in the system can also promote the diffusion of the activated carbon with conductive properties inside the sediment, enhance the conductive properties inside the sediment, and greatly improve the biocurrent restoration effect of the system. This integrated technology system forms an independent, organic repair module monomer with strong repair performance under the close entanglement of aquatic plant roots. These monomers are modularly assembled with their anodes and cathodes in parallel to form a portable and large-scale device for enhanced repair of complex pollution in lakes and bays. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the repair module of the present invention.

[0027] Figure 2 This is a bottom view of the repair module of the present invention.

[0028] Figure 3 This is a schematic diagram of the structure of the portable and modular lake pollution remediation device of the present invention.

[0029] Figure 4 This is a physical picture of the transplantation of the repair module described in the present invention.

[0030] Figure 5 This is a diagram showing the operating effect of the aquatic plant root control system of the present invention.

[0031] Figure 6 This is a repair effect diagram of the modular application of the present invention.

[0032] Figure 7 The removal performance of the integrated system for lake pollutants under different process conditions.

[0033] Figure 8 It is the structural characteristics of the microbial communities in different ecological niches of plants within the system.

[0034] In the figure, 1 is the cathode, 2 is the shell, 3 is the anode, 4 is the root control plate, 5 is the matrix, 6 is the aquatic plant, 7 is the resistor, 8 is the cathode wire, and 9 is the anode wire. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with specific drawings and embodiments.

[0036] Example 1

[0037] Sediment samples from Dashui Port, Dongshan Town, Suzhou (31°4′ N, 120°24′ E), which are often polluted by oil spills (motor oil, diesel, etc.), were selected to conduct on-site restoration experiments on these sediments with high composite pollution and high ecological risks ( Figure 6 ).

[0038] The portable and modular lake and bay pollution remediation device adopted includes 300 sets of remediation modules, wherein the remediation module includes a cathode and an aquatic plant root control system at least partially set in the sediment, wherein the aquatic plant root control system includes an outer shell, an anode, a root control plate and a matrix, wherein the cathode and the anode are connected through an external circuit, the cathode floats on the overlying water body, the outer shell is a cylinder with upper and lower openings, wherein the matrix, the root control plate and the anode are arranged in sequence from top to bottom in the outer shell, and aquatic plants are planted in the matrix, the outer shell is provided with pores, the root control plate is a mesh plate matching the inner diameter of the outer shell, and the root control plate is arranged in the sediment below.

[0039] The shell is cylindrical and has a diameter of 30 cm.

[0040] The surface of the shell has concave parts and convex parts, the concave parts and convex parts are arranged alternately in a corrugated shape, the top of the convex part is provided with the stomata, and the number of stomata is 190. The structure is helpful for the root growth and root control of aquatic plants and large-scale transplantation.

[0041] The anode is carbon felt or graphite felt with a thickness of 2-3 mm and a height of 8 cm.

[0042] The anode surrounds the bottom of the aquatic plant root control system.

[0043] The cathode is carbon felt or graphite felt with a thickness of 2-3 mm, a length of 86 cm and a width of 8 cm.

[0044] The cathode floats on the water surface by means of a floating rod.

[0045] The aquatic plants are foxtail algae, Vallisneria, reed, calamus and gum grass.

[0046] The mesh spaces of the root control plate are 1 cm squares.

[0047] The matrix is ​​conductive coconut shell activated carbon.

[0048] The coconut shell activated carbon has a conductivity of 50-100 W / cm.

[0049] The thickness of the substrate in each of the plant root control systems is 3 to 5 cm.

[0050] The amount of substrate laid in each plant root control system is 1.5-3.5 kg / m 2 That is, based on the area of ​​the root control board, 1.5-3.5 kg of substrate is laid on each square meter of the root control board.

[0051] The repair modules are connected in parallel.

[0052] Transplant the selected aquatic plant seedlings ( Figure 4 ), planted in aquatic plant root control systems ( Figure 1 ) in the matrix, the roots of aquatic plants can penetrate into the polluted sediments under the action of the root controller, and as the plant roots go deeper ( Figure 5 ), can carry a conductive matrix and flexibly disperse into the contaminated sediments, enhance the conductive properties inside the sediments, and improve the repair performance of the integrated system bioelectric current.

[0053] Furthermore, the repair module monomer ( Figure 4 ) for modular assembly ( Figure 3 ), the anodes 3 of each monomer are connected in parallel using anode wires 9, the cathodes 1 of each monomer are also connected in parallel using cathode wires 8, and an external resistor 7 of 100 ohms is connected in series between the anodes and cathodes. The modular integrated system is installed as a set at the lake bay site ( Figure 6 ). The test results show that under different process conditions, the system has a removal rate of 62%-90% for PAHs in sediments, among which the removal rate of PAHs in sediments under the combination system 2 can reach about 90% ( Figure 7 ). Figure 7 Combination system 1, combination system 2 and combination system 3 are the treatment group of Example 1 of the present invention; and combination system 4, combination system 5 and combination system 6 are the control groups of traditional plant-microorganism fuel cells (no root control plate is used, and aquatic plants are directly planted in the anode area). Their removal rate of polycyclic aromatic hydrocarbons in sediments is about 60.8%, which is significantly lower than the treatment effect of combination system 1, combination system 2 and combination system 3.

[0054] In addition, molecular biological methods were used to further analyze the structural characteristics of microbial communities in different ecological niches of plants in the system, and it was found that the complex interaction between electrochemically active microorganisms and rhizosphere microorganisms and root microorganisms of aquatic plants accelerated the degradation of polycyclic aromatic hydrocarbons in sediments ( Figure 8 ).

Claims

1. A portable and modular lake pollution remediation device, characterized in that: Includes several repair modules, The restoration module includes a cathode and an aquatic plant root control system at least partially disposed in the sediment. The aquatic plant root control system comprises an outer shell, an anode (3), a root control plate and a matrix, the cathode and the anode (3) are connected via an external circuit, the cathode floats on an overlying water body, the outer shell is in the shape of a cylinder with openings at the top and bottom, the inner shell contains the matrix, the root control plate and the anode (3) from top to bottom, the aquatic plants are planted in the matrix, the outer shell is provided with pores, the root control plate is a mesh plate matching the inner diameter of the outer shell, and the root control plate is arranged in the sediment below; The anode (3) surrounds the bottom of the aquatic plant root control system; The surface of the shell has concave parts and convex parts, the concave parts and convex parts are arranged alternately in a corrugated shape, and the air hole is arranged at the top of the convex part.

2. The portable and modular lake pollution remediation device according to claim 1 is characterized in that: The shell is cylindrical.

3. The portable and modular lake pollution remediation device according to claim 1 is characterized in that: The anode or the cathode is carbon felt or graphite felt.

4. The portable and modular lake pollution remediation device according to claim 1 is characterized in that: The aquatic plants are submerged plants or emergent plants.

5. The portable and modular lake pollution remediation device according to claim 1 is characterized in that: The matrix is ​​conductive coconut shell activated carbon.

6. The portable and modular lake pollution remediation device according to claim 5, characterized in that: The amount of substrate laid in each plant root control system is 1.5-3.5 kg / m 2 .

7. The portable and modular lake pollution remediation device according to claim 1 is characterized in that: The repair modules are connected in parallel.

8. Use of the portable and modular lake and bay pollution restoration device according to any one of claims 1 to 7 in restoring complex lake and bay pollution.

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