Circulating water fish culture system with higher-place pond and constructed wetland combined microbial fuel cell

Abstract

The invention relates to the field of aquaculture, and discloses a higher-place pond and constructed wetland combined microbial fuel cell circulating water fish culture system which comprises a higher-place pond culture unit used for culturing fishes in a pond higher than the ground water level; the controller is used for controlling the pond water level of the higher-place pond culture unit and discharging sewage from the bottom of the pond; the constructed wetland microbial fuel cell system comprises a constructed wetland and a constructed wetland microbial fuel cell, and the constructed wetland is used for preliminarily purifying circulating water; the constructed wetland microbial fuel cell is used for purifying circulating water again and carrying out microbial power generation; the reservoir is connected with a water outlet in the top of the constructed wetland microbial fuel cell and is used for storing purified water. The effects of improving the breeding efficiency and the yield are achieved by purifying the breeding tail water, reducing the proportion of the water purification area and increasing the area of the breeding area, electricity can be generated while the water body is purified, system resources are fully utilized, the water body is recycled, and water resources are saved.

Description

Technical Field

[0001] The present invention relates to the field of aquaculture, and in particular to a high-level pond combined with an artificial wetland microbial fuel cell circulating water fish farming system. Background Art

[0002] China is a major aquaculture country, with aquaculture production accounting for more than 60% of the world's aquaculture production. Aquaculture products play a prominent role in improving the dietary structure of residents and supplying high-quality protein, and have made important contributions to ensuring China's food security. As the main production method of aquaculture in China, pond aquaculture production accounts for more than 50% of the total aquaculture production and plays a key role in aquaculture production. However, traditional intensive pond aquaculture has had an adverse impact on the surrounding environment due to the discharge of tail water; in addition, pond aquaculture has a high dependence on clean water resources, and with the reduction of available water resources, traditional pond aquaculture has also been restricted. Therefore, it is imperative to explore and develop cleaner and more efficient aquaculture models.

[0003] The high-level pond recirculating aquaculture system (HLP-RAS) is an intensive aquaculture method that combines modern engineering technology and ecological regulation principles. This model is usually located in coastal or inland high-level areas, using the natural terrain gradient to construct stepped aquaculture units. Through the high-level difference terrain and the organic combination of the pond body and the closed-loop water treatment system, efficient recycling of water resources and precise regulation of the aquaculture environment are achieved. High-level pond aquaculture refers to aquaculture in ponds above the ground. For example, the water depth is 2m, about 0.3 - 0.5m above the ground water level, and there is still a part below the ground. This model combines the spatial advantages of high-level pond aquaculture and the ecological benefits of recirculating aquaculture, and uses multi-level water treatment processes such as physical filtration, biological purification, and disinfection and sterilization to form a semi-closed or fully closed water circulation system, significantly reducing the dependence on external water bodies and the risk of environmental pollution. Compared with the traditional aquaculture model, HLP-RAS has the advantages of stable water quality, continuous production throughout the year, high oxygen content, temperature control, high yield, etc. [1] , and at the same time, the aquaculture tail water can achieve up-to-standard discharge after ecological treatment, without negative impact on the water ecological environment, and has high economic and ecological benefits [2 , 3], which is an advanced model that combines efficient production and environmental protection in the modern aquaculture field. However, this aquaculture model still has certain limitations. First, the purification area covers a large area, usually reaching 15 times the aquaculture area, which greatly limits the area available for aquaculture production; second, the purification efficiency of this aquaculture model is low, and the removal rate of pollutants for one cycle of the aquaculture water body is only about 20%. Therefore, it is necessary to increase the number of water body cycles, increasing aquaculture energy consumption and costs; finally, the collection and treatment of fish feces in high-level ponds require additional treatment facilities, increasing aquaculture investment.

[0004] Constructed wetlands (CW) are ecosystems that simulate natural ecosystems. In a certain depression, a mixed substrate is placed, and aquatic plants are planted. As sewage flows through the gaps in the substrate, an ecosystem with the ability to degrade sewage is constructed. There are three main parts functioning inside, namely substrate adsorption and precipitation, microbial transformation, and aquatic plant absorption [4]. Constructed Wetland-Microbial Fuel Cells (CW-MFCs) are a new type of water treatment technology that combines constructed wetland technology and microbial fuel cell technology organically [5]. The basic principle of CW-MFCs is to utilize the interaction between wetland plants, microorganisms, and electrodes to convert organic matter in wastewater into electrical energy. In the CW-MFCs system, when wastewater passes through the wetland, organic matter is decomposed by microorganisms to produce electrons and protons. The electrons reach the anode through the transfer of microorganisms, and then reach the cathode through the external circuit, thus forming an electric current. Protons are transferred to the cathode through the wetland medium and combine with oxygen and electrons to form water, completing the entire electrochemical process. This process not only achieves the treatment of wastewater but also generates electrical energy [6]. However, if the organic matter in CW-MFCs cannot be replenished in time after consumption, it will lead to a gradual weakening of its power generation performance.

[0005] The references are as follows:

[0006] [1] Liu Xujia, Wang Zhicheng, Xiong Xiangying, et al. Water quality treatment effect of factory recirculating aquaculture of groupers in Guangxi [J]. Fisheries Modernization, 2019, 46(2): 6.

[0007] [2] Wang Feng, Lei Jilin, Gao Chunren, et al. Research progress on water quality treatment of factory recirculating aquaculture models at home and abroad [J]. Engineering Sciences in China, 2013, 15(10): 16 - 23.

[0008] [3] Zhao Junkai, Zhang Jiandong, Chen Gang, et al. Operation effect of hybrid groupers cultured in a recirculating water system [J]. Journal of Guangdong Ocean University, 2019(2): 8.

[0009] [4] Li Xiaodong, Sun Tieheng, Li Haibo, Wang Hong. Research progress on phosphorus removal by constructed wetlands [J]. Acta Ecologica Sinica, 2007(03): 1226 - 1232

[0010] [5]Bajracharya S, Sharma M, Mohanakrishna G, et al. An overview on emerging bioelectrochemical systems (bess): Technology for sustainable electricity, waste remediation, resource recovery, chemical production and beyond[J]. Renewable Energy, 2016, 98: 153-170.

[0011] [6]Hassan H, Jin B, Donner E, et al. Microbial community and bioelectrochemical activities in mfc for degrading phenol and producing electricity: Microbial consortia could make differences[J]. Chemical Engineering Journal, 2018, 332: 647-657.

[0012] [7]A circulating high-level pond fish farming system. CN112544535A. State Intellectual Property Office of the People's Republic of China, March 26, 2021. Zunyi Normal University. CN202011231302.1. Summary of the Invention

[0013] In order to overcome or alleviate one or more of the above technical problems, the object of the present invention is to provide a circulating water fish farming system combining a high-level pond, an artificial wetland and a microbial fuel cell, which is an ecological and environmentally friendly fish farming system for recycling purified aquaculture tail water. The system combines high-level pond farming, bottom sewage discharge device, aquaculture tail water circulation facility, vertical subsurface flow artificial wetland and microbial fuel cell technology to improve the purification efficiency of aquaculture tail water, realize water circulation utilization, and recover part of the energy.

[0014] The present invention provides the following technical solutions:

[0015] A circulating water fish farming system combining a high-level pond, an artificial wetland and a microbial fuel cell, comprising:

[0016] A high-level pond farming unit (1) for farming fish in a pond above the ground water level;

[0017] A controller (2), which is connected to the bottom of the pond of the high-level pond aquaculture unit (1), is used to control the water level of the pond of the high-level pond aquaculture unit (1) and achieve bottom sewage discharge from the pond;

[0018] An artificial wetland microbial fuel cell system (3), including an artificial wetland and an artificial wetland microbial fuel cell, is connected to the artificial wetland microbial fuel cell through a water passage (16) at the bottom of the artificial wetland. The artificial wetland is used for preliminary purification of circulating water; the artificial wetland microbial fuel cell is used for secondary purification of circulating water and microbial power generation;

[0019] A reservoir (4), which is connected to the water outlet at the top of the artificial wetland microbial fuel cell, is used to store purified water;

[0020] The high-level pond aquaculture unit (1), the controller (2), the artificial wetland microbial fuel cell system (3) and the reservoir (4) are sequentially connected through a water circulation pipeline (5).

[0021] According to some embodiments, the controller (2) includes an inner water storage tank and an outer water storage tank surrounding the periphery of the inner water storage tank. The side wall of the inner water storage tank is lower than the side wall of the outer water storage tank. The lower end of the inner water storage tank is connected to the bottom end of the high-level pond aquaculture unit (1) through a first pipeline (8). The lower end of the outer water storage tank is connected to the top of the artificial wetland through a second pipeline (9). The highest water level height of the inner water storage tank is consistent with the highest aquaculture water level of the pond of the high-level pond aquaculture unit (1).

[0022] According to some embodiments, the artificial wetland is provided with emergent plants and a first wetland substrate from top to bottom. The artificial wetland microbial fuel cell is provided with a cathode plate (20), floating plants and a second wetland substrate from top to bottom. Multiple anode plates (21) are provided at different heights at the bottom of the second wetland substrate.

[0023] According to some embodiments, the first wetland substrate includes fine sand, zeolite, activated carbon, ceramsite, volcanic rock and cobblestone from top to bottom in sequence; the second wetland substrate includes cobblestone, volcanic rock, ceramsite, activated carbon and zeolite from top to bottom in sequence.

[0024] According to some embodiments, the particle size range of the zeolite is 1-2 cm, the particle size range of the activated carbon is 2-3 cm, the particle size range of the ceramsite is 3-5 cm, the particle size range of the volcanic rock is 5-8 cm, and the particle size range of the cobblestone is 2-10 cm.

[0025] According to some embodiments, the pond of the high-level pond aquaculture unit (1) is conical, and the bottom of the pond is a slope with an inclined angle of 10-15° with the horizontal plane. The lowest point of the cone is connected to the inner water storage tank through a first pipeline (8).

[0026] According to some embodiments, there are two water storage pools, which are connected by a water pump (22) and a pipeline. One is located beside the constructed wetland - microbial fuel cell, and the other is located at a position higher than the high - level pond aquaculture unit (1). The water pump (22) pumps the water in the lower water storage pool (4) to the higher water storage pool (4).

[0027] According to some embodiments, the second pipeline (9) is connected to a number of third pipelines (18) laid flat on the water surface of the constructed wetland, and a plurality of water outlet holes are arranged on the third pipeline (18).

[0028] According to some embodiments, the diameter of the first pipeline (8) is larger than that of the second pipeline (9); the diameter of the second pipeline (9) is larger than that of the third pipeline (18).

[0029] According to some embodiments, the area ratio of the high - level pond aquaculture unit (1) to the constructed wetland microbial fuel cell system (3) is 1:0.1 - 1:0.15.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The high - level pond combined with the constructed wetland microbial fuel cell circulating water fish - farming system provided by the present invention addresses the problem of the excessive proportion of the water purification area in traditional aquaculture. Through optimized layout and efficient purification technologies, it greatly reduces the area proportion of the water purification area. This not only saves space but also allows more areas to be used for aquaculture, thereby improving aquaculture efficiency and output. Regarding the problem of frequent water circulation and high energy consumption in traditional aquaculture, by improving the purification efficiency, reducing the number of water circulation times, and reducing the energy consumption during operation, the cost is saved. Regarding the difficult problem of collecting and treating fish feces, the controller is used to discharge fish feces from the bottom, and the constructed wetland is combined to treat fish feces, achieving efficient and economical treatment of fish feces. Regarding the problem that organic matter needs to be replenished in time after consumption in the constructed wetland microbial fuel cell, the sewage discharged from the high - level pond aquaculture unit contains a large amount of fish feces, which can provide organic matter for the microbial fuel cell in a timely manner, ensuring that the microbial fuel cell can continuously and stably generate electricity while degrading the feces. This recycling of organic matter not only saves the cost of external organic matter supplementation but also improves the resource utilization efficiency of the entire system.

[0032] Among them, the controller for bottom sewage discharge has internal and external memories and is used to control the discharge of sewage flowing out of the high-level pond aquaculture unit; the laying method of the vertical subsurface flow constructed wetland enables the sewage to fully contact with the matrix material, plant roots and microorganisms inside the wetland, so as to achieve the effect of efficiently removing pollutants in the sewage; the construction method of the microbial fuel cell has the effect of purifying the aquaculture water body while using its organic matter to supply microorganisms to generate electricity; the setting of the circulating water pipeline has the effect of recycling water bodies and saving water resources; the ratio setting of the fish culture pond and the purification area greatly increases the proportion of the aquaculture area, thereby improving the aquaculture efficiency and output.

[0033] In summary, the high-level pond combined with constructed wetland microbial fuel cell circulating water fish farming system provided by the present invention is a comprehensive aquaculture mode. Through the high-density aquaculture in the high-level pond, the preliminary purification of water quality by the constructed wetland, and the simultaneous in-depth purification of water quality by the constructed wetland - microbial fuel cell and energy recovery, the efficient purification, recycling of the aquaculture water body and the sustainable management of resources are realized. This circulating water aquaculture mode not only improves the purification effect, saves water resources, but also reduces the proportion of the water purification area, thereby increasing the aquaculture area, improving the aquaculture efficiency, and at the same time being able to supplement organic matter to the microbial fuel cell system in a timely manner to make it continuously generate electricity. The coupling of multiple technologies in this aquaculture mode provides a new solution for sustainable aquaculture and has significant economic and ecological benefits. Brief Description of the Drawings

[0034] Figure 1 It is a plan view of the high-level pond combined with constructed wetland microbial fuel cell circulating water fish farming system provided in Embodiment 1 of the present invention.

[0035] Figure 2 It is a schematic diagram of the high-level pond aquaculture unit provided in Embodiment 1 of the present invention.

[0036] Figure 3 It is a schematic diagram of the controller provided in Embodiment 1 of the present invention.

[0037] Figure 4 It is a schematic diagram of the constructed wetland microbial fuel cell system and the reservoir provided in Embodiment 1 of the present invention.

[0038] Figure 5 It is a sectional view of the high-level pond combined with constructed wetland microbial fuel cell circulating water fish farming system provided in Embodiment 1 of the present invention.

[0039] Figure 6 It is a schematic layout diagram of the existing high-level pond combined with biological purification pond circulating water aquaculture provided in Embodiment 2 of the present invention.

[0040] Figure 7This is a field diagram of the existing high-level pond combined with a biological purification pond for circulating water aquaculture provided in Embodiment 2 of the present invention.

[0041] In the figure:

[0042] 1 - High-level pond aquaculture unit, 2 - Controller, 3 - Constructed wetland microbial fuel cell system, 4 - Reservoir, 5 - Water circulation pipeline, 6 - Sewage pipe, 7 - Water storage device, 8 - First pipeline, 9 - Second pipeline, 10 - Fine sand, 11 - Zeolite, 12 - Activated carbon, 13 - Ceramsite, 14 - Volcanic rock, 15 - Pebbles, 16 - Water passage, 17 - Emergent plant, 18 - Third pipeline, 19 - Floating plant, 20 - Cathode plate, 21 - Anode plate, 22 - Water pump. Detailed implementation manners

[0043] The present invention will be described in detail below in conjunction with embodiments and the accompanying drawings. However, it should be understood that the embodiments and the drawings are only used for exemplary description of the present invention and do not constitute any limitation to the protection scope of the present invention. All reasonable transformations and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0044] The present invention will be further described below in conjunction with the accompanying drawings.

[0045] Embodiment 1

[0046] As Figure 1 shown, this embodiment provides a high-level pond combined with a constructed wetland microbial fuel cell circulating water fish farming system, including a high-level pond aquaculture unit 1, a controller 2 for bottom sewage discharge, a constructed wetland microbial fuel cell system 3, a reservoir 4, and a water circulation pipeline 5. High-density intensive aquaculture is carried out in the fish pond. The aquaculture tail water enters the controller 2 through the sewage pipe in the direction of the arrow in the figure. When the aquaculture tail water reaches a certain height, it flows out of the controller 2 and enters the area of the constructed wetland microbial fuel cell system 3. After being adsorbed by the matrix material and purified by plants and microorganisms, it flows back to the reservoir and finally enters the fish pond through the water pump for repeated use.

[0047] Among them, the longitudinal section structure of the high-level pond aquaculture unit 1 is as Figure 2 shown, which is a circular pond made of materials such as bricks, sediment, and steel bars. The soil on the pond slope is relatively hard. The diameter of the fish pond is 16m, the height is 2.5m, and the water depth is 2m. The pond is 30 - 50cm higher than the ground, which is convenient for the introduction and outflow of water and reduces the energy consumption of the water pump. The bottom of the pond is a slope with an inclined angle of 10 - 15° to the horizontal position, so that feces can gather towards the center of the pond bottom. The feces contain rich organic matter, which can supply the microorganisms in the constructed wetland microbial fuel cell system 3 for power generation and degrade it at the same time. A sewage pipe 6 with a diameter of 20cm is arranged at the bottom center of the fish pond, and a pipeline with a diameter of 20cm is laid to connect the controller 2.

[0048] As shown in Figure 3 , the function of the controller 2 is to control the sewage in the high-level pond aquaculture unit 1 from flowing out continuously. Instead, it will only flow out when the water level exceeds a certain height. It has the function of realizing bottom sewage discharge from the high-level pond and saving energy consumption in the purification process. The controller 2 includes an inner water storage tank and an outer water storage tank surrounding the inner water storage tank. The height of the inner water storage tank is lower than that of the outer water storage tank, and the height of the outer water storage tank is lower than the height of the pool wall of the high-level pond aquaculture unit 1. The height of the inner water storage tank wall = the water depth of the high-level pond = 2m. The height difference between the inner and outer water storage tank walls is about 0.1m. The height of the outer water storage tank wall is about 2.1m, and the height of the high-level pond wall is 2.5m. The lower end of the inner water storage tank is connected to the high-level pond aquaculture unit 1 through the first pipeline 8, and the lower part of the outer water storage tank is connected to the CW-MFC through the second pipeline 9. The aquaculture tail water enters the inner water storage tank through the first pipeline 8. When the water level height exceeds the height of the inner pipe wall, the sewage will overflow into the outer water storage tank and flow out through the second pipeline 9, and then enter the purification treatment area of the constructed wetland microbial fuel cell system 3. The water storage tank 7 consists of an inner and an outer part, and the height difference between the inner and outer parts is about 0.1m. The material of the water storage tank is polyethylene. The diameter of the first pipeline 8 is 0.2m, and the diameter of the second pipeline 9 is 0.1m. The water level height in the inner water storage tank of the controller 2 is the same as the pond water level height of the high-level pond aquaculture unit 1, and is 0.5m higher than the height of the constructed wetland microbial fuel cell system 3.

[0049] The constructed wetland microbial fuel cell system 3 on the left and the water storage tank 4 on the right are as shown in Figure 4 . Figure 4 As shown, the constructed wetland microbial fuel cell system 3 is evenly divided into two parts, namely the constructed wetland on the left and the constructed wetland - microbial fuel cell on the right. The water passage 16 between the two parts is located at the bottom and has a height of about 20cm. The sewage flows into the top of the constructed wetland from the second pipeline 9 of the controller 2. To make the aquaculture tail water flow into the constructed wetland relatively evenly from the surface, multiple staggered third pipelines 18 with smaller diameters are set in the second pipeline 9 of the part entering the constructed wetland to make the flowing water body evenly distributed on the surface part of the constructed wetland. Then, uniform small holes are set in the third pipeline 18 so that the flowing aquaculture tail water can be more evenly distributed on the surface and then flow downward. The water flow path is as shown by the arrow. It passes through the substrate material of the constructed wetland area and reaches the constructed wetland - microbial fuel cell area through the water passage, and then flows upward to the highest point of the constructed wetland - microbial fuel cell area. The water overflows and enters the water storage tank 4.

[0050] The wetland plants used to construct the constructed wetland can be various aquatic plants with good purification effects; the substrate materials for constructing the constructed wetland can be various materials with strong adsorption ability and large surface area. The size ratios of each part of the system can be within the range of ±20%.

[0051] ​​In the artificial wetland area, from top to bottom, there are emergent plants, 10 cm of fine sand, 15 cm of zeolite, 5 cm of activated carbon, 20 cm of ceramsite, 25 cm of volcanic rock, and 25 cm of cobblestones; in the artificial wetland - microbial fuel cell area, from top to bottom, there are floating plants, 20 cm of cobblestones, 20 cm of volcanic rock, 20 cm of ceramsite, 10 cm of activated carbon, and 15 cm of zeolite. Three anode plates 21 are respectively laid at positions 10 cm, 30 cm, and 50 cm from the bottom, and the cathode plate 20 is laid in the surface water body. The matrix particle sizes are 1 - 2 cm for zeolite, 2 - 3 cm for activated carbon, 3 - 5 cm for ceramsite, 5 - 8 cm for volcanic rock, and 2 - 10 cm for cobblestones, which are laid in a staggered manner. The artificial wetland microbial fuel cell system 3 is about 6 m long and about 4 m wide. The reservoir 4 has a side length of about 3 m and a height of about 1 m. The water pump is located on the reservoir wall, 10 cm from the bottom. The area of the high - level pond aquaculture unit area in this system is about 201 m 2 , and the water purification area is about 24 m 2 , and the area ratio of the aquaculture area to the water purification area is about 1:0.1 - 1:0.15.

[0052] As Figure 5 shown, the aquaculture wastewater in the high - level pond aquaculture unit 1 enters the controller 2 from the bottom. When the water level is higher than the height of the inner water storage wall in the controller 2, it overflows and flows into the outer water storage and then enters the top of the artificial wetland through the second pipeline 9. After preliminary filtration, it enters the artificial wetland microbial fuel cell 3 beside the bottom of the artificial wetland for further filtration and microbial power generation, and then enters the reservoir 4 for water storage. The electricity generated by the artificial wetland microbial fuel cell system 3 in this embodiment is about 6.78 w - 7.46 w, which can be used to supply small - power electrical appliances such as light bulbs. In actual aquaculture, there should be multiple units, and the electricity generation will increase; another reservoir 4 is set at the high position of the high - level pond aquaculture unit 1, and the water in the lower reservoir 4 is pumped to the higher reservoir 4 to facilitate the replenishment of purified water to the pond of the high - level pond aquaculture unit 1 at any time.

[0053] The area ratio of the high - level pond aquaculture unit 1 to the artificial wetland microbial fuel cell system 3, that is, the ratio range of the fish - farming pond area to the purification area, is preferably between 1:0.1 - 1:0.15, which has the beneficial effect of increasing the proportion of the aquaculture area and improving the aquaculture efficiency and output. The depth ratio of this embodiment is 2:1.

[0054] Through simulation calculation, the high - level pond combined with artificial wetland microbial fuel cell circulating water fish - farming system provided in this embodiment has the following improvement effects:

[0055] (1) Improve the aquaculture environment. The ammonia - nitrogen removal rate of the aquaculture tail water circulation once is about 39%, the nitrite removal rate is about 75%, the conductivity is reduced by about 22%, and the suspended solids are reduced by about 23%.

[0056] (2) Increase the proportion of aquaculture area. Reduce the ratio of the aquaculture area to the tail water purification area from 1:15 to 1:0.1 - 1:0.15, significantly increasing the proportion of the aquaculture area.

[0057] (3) Reduce the dependence on external water resources. Compared with before the purification of aquaculture tail water, more than 90% of the water resources are recycled, significantly reducing the water consumption.

[0058] (4) Reduce the cost of fish manure treatment. Compared with the traditional fish manure collection and treatment, this embodiment can reduce the input cost of fish manure treatment by more than 60%.

[0059] (5) Reduce energy consumption. Compared with traditional recirculating aquaculture, the number of water circulation times in this embodiment is significantly reduced, and the operating energy consumption and cost are reduced by more than 1 time.

[0060] (6) Realize partial resource recovery, and 565.99mW - 622.18mW of electric energy can be continuously generated per square meter per second.

[0061] Example 2

[0062] This example is a comparative example. As Figure 7 , this example provides a site plan of the recirculating aquaculture of high-level ponds combined with biological purification ponds in an existing aquaculture farm somewhere. Figure 6 It is a layout schematic diagram of the recirculating aquaculture of high-level ponds combined with biological purification ponds. This aquaculture farm adopts the recirculating aquaculture mode of high-level ponds. The total area of the ponds is about 32 mu. The recirculating aquaculture infrastructure of high-level ponds includes 7 rebuilt and constructed high-level ponds with a total area of about 2 mu, and 1 ecological purification pond with an area of about 30 mu. The area ratio of the aquaculture area to the purification area is 1:15. The aquaculture tail water of the high-level ponds is discharged into the ecological purification pond for water quality purification. The purified water is pumped back to the distribution pond through lifting, and after disinfection, it is transported back to the aquaculture ponds through the water inlet pipe for recycling, realizing closed internal circulation intensive aquaculture.

[0063] The water quality purification efficiency was detected in February, May, August, and November 2023 respectively. The detection indicators include total nitrogen, total phosphorus, ammonium nitrogen, nitrite nitrogen, etc., as shown in Table 1 attached at the back. The total nitrogen purification rate in the 4 seasons is in the range of 16.95% - 25.24%, with an average of 24.46%; the total phosphorus purification rate is in the range of 13.40% - 56.90%, with an average of 32.77%; the ammonium nitrogen purification rate is in the range of 40.61% - 72.24%, with an average of 52.63%; the nitrite nitrogen purification rate is in the range of 25.16% - 65.53%, with an average of 41.51%. The average removal rate of each index in the 4 months is in the range of 24.46% - 52.63%, with an average of 37.84%. This result is the purification rate of 2 cycles.

[0064] Compared with the circulating water fish farming system using a high-level pond combined with a constructed wetland microbial fuel cell for purifying aquaculture tail water in Example 1, the purification effects of purifying once in Example 1 include an ammonia nitrogen removal rate of about 39% and a nitrite removal rate of about 75%, etc. It can be compared that Example 1 has a better purification effect on aquaculture tail water. In addition, it can be compared that the proportion of the purification area in Example 1 is significantly reduced, and the proportion of the aquaculture area is increased.

[0065] Table 1 Purification efficiency of water quality indicators in the circulating water high-level pond aquaculture mode

[0066]

[0067]

[0068] Note: The values are expressed as mean ± standard error.

[0069] The above embodiments are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system, characterized by: It includes: A raised pond culture unit (1) for culture fish in a pond above ground water level; A controller (2) is connected to the bottom of the pond of the high-level pond aquaculture unit (1) and is used to control the pond water level of the high-level pond aquaculture unit (1) and to discharge sewage from the bottom of the pond; An artificial wetland microbial fuel cell system (3) comprises an artificial wetland and an artificial wetland microbial fuel cell, which is connected to the artificial wetland microbial fuel cell through a water passage (16) at the bottom of the artificial wetland, wherein the artificial wetland is used for preliminary purification of circulating water; and the artificial wetland microbial fuel cell is used for re-purifying circulating water and performing microbial power generation; A water reservoir (4), connected to the water outlet at the top of the artificial wetland microbial fuel cell, for storing purified water; The high-level pond culture unit (1), the controller (2), the artificial wetland microbial fuel cell system (3) and the water reservoir (4) are connected in sequence via a water circulation pipeline (5).

2. According to claim 1, the high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system is characterized by: The controller (2) comprises an inner water reservoir and an outer water reservoir surrounding the inner water reservoir, the side wall of the inner water reservoir being lower than the side wall of the outer water reservoir, the lower end of the inner water reservoir being connected to the bottom end of the high-level pool breeding unit (1) via a first pipe (8), and the lower end of the outer water reservoir being connected to the top of the artificial wetland via a second pipe (9), and the highest water level of the inner water reservoir being consistent with the highest breeding water level of the pond of the high-level pool breeding unit (1).

3. According to claim 2, the high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system is characterized by: The artificial wetland is provided with emergent plants and a first wetland matrix from top to bottom, the artificial wetland microbial fuel cell is provided with a cathode plate (20), floating plants and a second wetland matrix from top to bottom, and a plurality of anode plates (21) are provided at different heights at the bottom of the second wetland matrix.

4. According to claim 3, the high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system is characterized by: The first wetland matrix includes fine sand, zeolite, activated carbon, expanded clay, volcanic rock and pebbles from top to bottom; the second wetland matrix includes pebbles, volcanic rock, expanded clay, activated carbon and zeolite from top to bottom.

5. The high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system according to claim 4 is characterized by: The particle size range of the zeolite is 1-2 cm, the particle size range of the activated carbon is 2-3 cm, the particle size range of the ceramsite is 3-5 cm, the particle size range of the volcanic rock is 5-8 cm, and the particle size range of the pebble is 2-10 cm.

6. The high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system according to claim 2 is characterized by: The pond of the high-level pond culture unit (1) is conical, and the bottom of the pond is a slope with an inclined angle of 10-15° to the horizontal plane. The lowest point of the cone is connected to the internal water storage tank through a first pipe (8).

7. The high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system according to claim 2 is characterized by: The water reservoirs include two, which are connected by a water pump (22) and a pipeline, one of which is located next to the artificial wetland-microbial fuel cell, and the other is located at a position higher than the high-level pond breeding unit (1). The water pump (22) pumps water from the lower water reservoir (4) to the higher water reservoir (4).

8. The high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system according to claim 2 is characterized by: The second pipe (9) is connected to a plurality of third pipes (18) laid flat on the water surface of the artificial wetland, and a plurality of water outlet holes are arranged on the third pipes (18).

9. The high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system according to claim 8 is characterized by: The diameter of the first pipeline (8) is greater than the diameter of the second pipeline (9); and the diameter of the second pipeline (9) is greater than the diameter of the third pipeline (18).

10. The high-level pool combined with artificial wetland microbial fuel cell circulating water fish farming system according to claim 1 is characterized by: The area ratio of the high-level pond culture unit (1) and the artificial wetland microbial fuel cell system (3) is 1:0.1 to 1:0.15.

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