An apparatus and method for treating pond aquaculture sewage by combining physics and biology

Abstract

A device and method for treating pond aquaculture sewage by combining physics and biology, belonging to the technical field of sewage treatment. It includes a primary biological reaction zone, a phosphorus-nitrogen conversion zone, and a secondary biological reaction zone; the secondary biological reaction zone is arranged between the primary biological reaction zone and the phosphorus-nitrogen conversion zone; a primary biological reaction filler is arranged at the bottom of the primary biological reaction zone, a secondary biological reaction filler is arranged in the secondary biological reaction zone, the side of the secondary biological reaction zone close to the primary biological reaction zone is the first filter layer, and the side of the secondary biological reaction zone close to the phosphorus-nitrogen conversion zone is the second filter layer. This invention has obvious effects on removing nitrogen and phosphorus in pond aquaculture sewage, combines physical materials and biological means for removal, will not have adverse effects on water, the physical materials used have a wide source and can be prepared in large quantities, and the floating plant water spinach also has certain economic value.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and more specifically, relates to a device and method for treating pond aquaculture sewage by combining physics and biology. Background Art

[0002] In recent years, the high-density intensive aquaculture mode has developed rapidly. While bringing relatively high aquaculture benefits, it has also led to serious eutrophication of the discharged sewage. Direct discharge into water bodies will cause water eutrophication, and entering the sewage treatment plant for treatment will greatly increase the cost. Treating aquaculture sewage has become a major problem.

[0003] The contents of nitrogen, phosphorus, ammonia nitrogen and nitrite nitrogen in aquaculture sewage also account for a relatively high proportion. However, compared with the sewage of other livestock farming, aquaculture sewage does not have so many suspended solids and residues, and the nitrogen and phosphorus contents are relatively small. This has led many aquaculture bases to choose to directly discharge it into natural water bodies. As an integrated and specialized means in freshwater aquaculture, freshwater pond aquaculture is widely used in coastal areas. However, the incomplete utilization of its bait will lead to an increase in water body nutrient elements, thus affecting the environment of the receiving water body. The average concentration of ammonia nitrogen in it reaches 1.5 mg / L, and the higher can reach about 40 mg / L.

[0004] Selecting to set up a device at the sewage outlet to treat excessive nitrogen and phosphorus in the discharged sewage will not cause adverse effects after the discharged sewage enters the water body. After retrieval, the invention patent "Treatment system and treatment method for treating low-carbon-nitrogen-ratio aquaculture wastewater" with the patent number CN107055775A discloses a method for wastewater treatment relying only on microbial reactions, which can effectively remove nitrogen nutrient salts in the water body, but the removal effects on total phosphorus and COD in the water body are relatively limited, and the treated wastewater still cannot be directly discharged into the receiving water body.

[0005] In addition, after retrieval, the invention patent "A biological-ecological combined sewage treatment device" with the patent number CN111233154A discloses a technical idea of combining aerobic and anoxic units, and a device with an ecological unit for planting water-purifying plants is set up later. However, its intercepting net uses traditional filter materials such as shale ceramsite and fly ash, resulting in poor intercepting effect and the problem of continuous accumulation of impurities blocking the water inlet, which further affects water body reoxygenation and is not conducive to improving transparency. Secondly, the fillers in its aerobic tank and anoxic tank are mostly suspended biological fillers, sponge fillers, and PE. The suspended biological fillers cannot provide enough carbon source for microorganisms as a reactor to improve microbial reactions. Only water-purifying plants are planted in the later ecological pond, and the effect of removing nitrogen and phosphorus is not obvious. Summary of the Invention

[0006] 1. Problems to be Solved

[0007] The present invention provides a device and method for treating pond aquaculture sewage by combining physics and biology, aiming to overcome the technical problem that the existing water treatment methods cannot safely and effectively remove nitrogen, phosphorus, and impurities in pond aquaculture sewage, and to provide a device and method for treating pond aquaculture sewage by combining physics and biology; through the reasonable arrangement of the primary biological reaction zone, the phosphorus-nitrogen conversion zone, and the secondary biological reaction zone, the cleanliness of pond aquaculture sewage can be safely and effectively improved.

[0008] 2. Technical Solution

[0009] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0010] A device for treating pond aquaculture sewage by combining physics and biology according to the present invention includes a primary biological reaction zone, a phosphorus-nitrogen conversion zone, and a secondary biological reaction zone; the secondary biological reaction zone is arranged between the primary biological reaction zone and the phosphorus-nitrogen conversion zone; a primary biological reaction filler is provided at the bottom of the primary biological reaction zone, a secondary biological reaction filler is provided in the secondary biological reaction zone, the side of the secondary biological reaction zone close to the primary biological reaction zone is the first filter layer, and the side of the secondary biological reaction zone close to the phosphorus-nitrogen conversion zone is the second filter layer.

[0011] Preferably, it further includes a pretreatment zone, and the pretreatment zone contains a microbial flocculant and a coagulant.

[0012] Preferably, the microbial flocculant includes a protein-polysaccharide biopolymer flocculant LF-Tou2 with high flocculation efficiency; and / or the coagulant includes polyaluminum chloride at a concentration of 20-50 mg / L.

[0013] Preferably, the first filter layer is made of polyamide fiber with a thickness of 2-4 mm, and the second filter layer is made of activated carbon fiber with a thickness of 5-7 mm.

[0014] Preferably, the primary biological reaction filler includes a filler with PHBV as the main body, and the secondary biological reaction filler includes a K3 annular filler.

[0015] Preferably, the phosphorus-nitrogen conversion zone includes algae and water spinach, and the algae include chlorella pyrenoidosa with a concentration of 6.5-8.0 mg / L and scenedesmus obliquus with a concentration of 0.5-1 mg / L.

[0016] Preferably, the length L1 of the pretreatment zone is 3-5 m, the length L2 of the primary biological reaction zone is 5-8 m, the length L3 of the secondary biological reaction zone is 0.2-0.5 m, and the length L4 of the phosphorus-nitrogen conversion zone is 10-12 m.

[0017] Preferably, a filter plate is provided between the pretreatment area and the primary biological reaction area. A water blocking area is provided at the bottom of the filter plate, and the height H3 of the water blocking area accounts for 1 / 3 - 2 / 3 of the height H4 of the filter plate. The water blocking area at the bottom can effectively block debris flows in the sewage and prevent the filter plate from being directly blocked when the sewage flows. When H3 accounts for 1 / 3 - 2 / 3 of H4, it can ensure that the relatively clear sewage in the upper part passes through, and can also block debris flows, improving the sewage discharge efficiency.

[0018] A method for treating pond aquaculture sewage by combining physics and biology according to the present invention is realized by using the device described in any one of the above. The sewage passes through the pretreatment area, the packing area, the porous filter screen area and the floating plant area in sequence.

[0019] Preferably, the ratio of the water surface height H2 of the sewage to the height H1 of the primary biological reaction packing is (1 - 1.5):1, and the flow rate of the sewage is 12 - 25 m / h. When the ratio of H2 to H1 is (1 - 1.5):1, it can effectively make the primary biological reaction packing fully contact with the sewage, improve its utilization rate, ensure full denitrification when the flow rate of the sewage is 12 - 25 m / h, and improve the sewage discharge efficiency.

[0020] 3. Beneficial effects

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) A device for treating pond aquaculture sewage by combining physics and biology according to the present invention includes a primary biological reaction area, a phosphorus and nitrogen conversion area and a secondary biological reaction area. The secondary biological reaction area is arranged between the primary biological reaction area and the phosphorus and nitrogen conversion area. The bottom of the primary biological reaction area is provided with primary biological reaction packing, and the secondary biological reaction area is provided with secondary biological reaction packing. One side of the secondary biological reaction area close to the primary biological reaction area is the first filter layer, and one side of the secondary biological reaction area close to the phosphorus and nitrogen conversion area is the second filter layer; by arranging the secondary biological reaction area between the primary biological reaction area and the phosphorus and nitrogen conversion area, when the sewage passes through the secondary biological reaction area, it will first be buffered and decelerated by the first filter layer, and the buffered sewage will fully interact with the primary biological reaction packing in the primary biological reaction area. When the sewage enters the secondary biological reaction area, it will be buffered and decelerated by the second filter layer again, and the retained sewage will interact with the secondary biological reaction packing again, so that the sewage is buffered and decelerated twice, achieving the effect of deeply removing nitrogen elements in the sewage by combining physics and biology, greatly improving the denitrification efficiency, and having a good removal effect on other impurities at the same time.

[0023] (2) A device for treating pond aquaculture sewage by combining physics and biology according to the present invention. The primary biological reaction filler includes a filler with PHBV as the main body, and the secondary biological reaction filler includes a K3 annular filler. First, the PHBV filler is used to remove the residual suspended impurities in the sewage. Then, the biological film formed by the K3 annular filler in water is used to further adsorb and remove the fine impurities in the sewage. At the same time, the nitrate nitrogen in the sewage can be reduced and removed. Under the buffering effect of the two-layer filter membrane, the biological film can effectively purify the sewage.

[0024] (3) A device for treating pond aquaculture sewage by combining physics and biology according to the present invention. The first filter layer is made of polyamide fiber with a thickness of 2 - 4 mm, and the second filter layer is made of activated carbon fiber with a thickness of 5 - 7 mm. By designing the materials and thicknesses of the two filter layers, the sewage first undergoes rough treatment through the first filter layer with a larger pore size and a thinner thickness, and then undergoes in-depth treatment through the second filter layer with a smaller pore size and a thicker thickness. The sewage is slowed down, so that it can fully react with the primary biological reaction filler or the secondary biological reaction filler, avoiding the direct blockage of the second filter layer with a smaller pore size by the sewage and affecting the stable progress of the subsequent sewage discharge process.

[0025] (4) A device for treating pond aquaculture sewage by combining physics and biology according to the present invention. The length L1 of the pretreatment area is 3 - 5 m, the length L2 of the primary biological reaction area is 5 - 8 m, the length L3 of the secondary biological reaction area is 0.2 - 0.5 m, and the length L4 of the phosphorus-nitrogen conversion area is 10 - 12 m. When the sewage passes through each area, it can effectively interact with the fillers or organisms in each area, ensuring the progress rate of the entire sewage discharge process and improving the sewage discharge efficiency.

[0026] (5) A device for treating pond aquaculture sewage by combining physics and biology according to the present invention. When the concentration of Chlorella vulgaris is 4 - 8.0 mg / L, the removal rates of ammonia nitrogen and nitrite nitrogen can reach over 80% and 75% respectively. When the concentration of Scenedesmus obliquus is 0.5 - 1 mg / L, the removal rate of nitrite nitrogen reaches over 80%. And Ipomoea aquatica can also remove over 70% of nitrogen and phosphorus in water and has certain economic value. In addition, planting Ipomoea aquatica can provide habitats and shelters for various aquatic organisms that feed on Chlorella vulgaris, etc., effectively preventing the overgrowth of Chlorella vulgaris, etc. Description of the Drawings

[0027] Figure 1 is a top view of a device for treating pond aquaculture sewage by combining physics and biology according to the present invention;

[0028] Figure 2 is a sectional view of a device for treating pond aquaculture sewage by combining physics and biology according to the present invention along the A - A plane.

[0029] In the figure:

[0030] 100, pretreatment area; 110, filter plate;

[0031] 200, primary biological reaction area; 211, primary biological reaction packing;

[0032] 300, secondary biological reaction area; 301, first filter layer; 302, second filter layer; 303, secondary biological reaction packing;

[0033] 400, phosphorus and nitrogen conversion area;

[0034] 600, algae;

[0035] 700, water spinach. Specific implementation manners

[0036] The present invention will be further described below in conjunction with specific embodiments.

[0037] The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limiting conditions under which the present invention can be implemented. Therefore, they do not have technical essential meanings. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that the technical content disclosed by the present invention can cover. At the same time, the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of clear narration and are not used to limit the scope that can be implemented. The change or adjustment of their relative relationships, without substantial change of the technical content, should also be regarded as the scope that the present invention can be implemented; in addition, the various embodiments of the present invention are not independent of each other, but can be combined; the "multiple" mentioned in the present invention refers to the number of 2 or more.

[0038] Example 1

[0039] A physical and biological combined device for treating pond aquaculture sewage in this embodiment includes a primary biological reaction area 200, a phosphorus and nitrogen conversion area 400, and a secondary biological reaction area 300; the secondary biological reaction area 300 is arranged between the primary biological reaction area 200 and the phosphorus and nitrogen conversion area 400; a primary biological reaction filler 211 is arranged at the bottom of the primary biological reaction area 200, a secondary biological reaction filler 303 is arranged in the secondary biological reaction area 300, a first filter layer 301 is on the side of the secondary biological reaction area 300 close to the primary biological reaction area 200, and a second filter layer 302 is on the side of the secondary biological reaction area 300 close to the phosphorus and nitrogen conversion area 400. By arranging the secondary biological reaction area 300 between the primary biological reaction area 200 and the phosphorus and nitrogen conversion area 400, when the sewage passes through the secondary biological reaction area 300, it will first be buffered and decelerated by the first filter layer 301, and the buffered sewage will fully interact with the primary biological reaction filler 211 in the primary biological reaction area 200. When the sewage enters the secondary biological reaction area 300, it will be buffered and decelerated again by the second filter layer 302, and the retained sewage will interact with the secondary biological reaction filler 303 again, so that the sewage is buffered and decelerated twice, and the nitrogen element in the sewage is deeply removed by the physical and biological combination method, greatly improving the nitrogen removal efficiency.

[0040] In this embodiment, a pretreatment area 100 is further included. Flocculants and coagulants can be added to the pretreatment area 100 during sewage treatment. A filter plate 110 is arranged between the pretreatment area 100 and the primary biological reaction area 200. The filter plate 110 can block larger-sized impurities in the sewage to avoid reducing the sewage discharge efficiency due to clogging of the first filter layer 301 and the second filter layer 302. In addition, the pretreatment area 100 also contains microbial flocculants and coagulants. By adding microbial flocculants and coagulants to the pretreatment area 100, the suspended substances in the water are treated first, and various toxic substances in the water are sedimented, effectively improving the water transparency and being beneficial to further improving the subsequent treatment effect.

[0041] In addition, the first filter layer 301 is made of polyamide fiber and has a thickness of 2-4 mm, and the second filter layer 302 is made of activated carbon fiber and has a thickness of 5-7 mm. By specifically setting the materials and thicknesses of the two filter layers, the sewage first undergoes rough treatment through the first filter layer 301 with a larger pore size and a thinner thickness, and then undergoes in-depth treatment through the second filter layer 302 with a smaller pore size and a thicker thickness, so that the sewage is decelerated in stages. Furthermore, the sewage can fully react with the primary biological reaction filler 211 and the secondary biological reaction filler 303, and it is prevented that the sewage is directly blocked by the second filter layer 302 with a smaller pore size, which affects the stable progress of the subsequent sewage discharge process. In addition, the second filter layer 302 is an ACF activated carbon fiber porous material. The activated carbon fiber contains a large number of micropores and has a large specific surface area. It can effectively remove color and odor through physical adsorption, and can also remove most organic pollutants and inorganic substances in the secondary effluent through chemical adsorption, which can greatly improve the water transparency. The activated carbon fiber material can utilize its own porous properties to adsorb the fine substances in the sewage on the one hand, and on the other hand, it can reduce the flow rate of the sewage and make it fully react with the primary biological reaction filler 211 and the secondary biological reaction filler 303 in the primary biological reaction zone 200 and the secondary biological reaction zone 300 respectively.

[0042] Among them, the primary biological reaction filler 211 is a PHBV filler in this embodiment. Under artificial aeration, PHBV can enhance the nitrification of microorganisms as a carbon source. The removal rate of ammonium nitrogen on the surface of PHBV can reach 90%, and its source is extremely wide. Various organic substances can be used as raw materials, such as starch, waste fruits and vegetables, food industry waste, etc. The secondary biological reaction filler 303 is a K3 ring-shaped filler in this embodiment. The K3 ring-shaped filler is used to form a microbial biofilm inside the activated carbon filter membrane. The formed biofilm can further adsorb and remove the fine impurities in the sewage, and at the same time can reduce and remove the nitrate nitrogen in the sewage. Therefore, under the buffering action of the two filter membranes of the first filter layer 301 and the second filter layer 302, the biofilm can effectively purify the sewage, can effectively remove the nutrients in the water, and prevent their concentration from being too high and affecting the subsequent biological treatment.

[0043] In this embodiment, a water blocking area is provided at the bottom of the filter plate 110, and the height H3 of the water blocking area accounts for 1 / 3 - 2 / 3 of the height H4 of the filter plate 110. The water blocking area at the bottom can effectively block solid impurities in the sewage, preventing the direct blockage of the filter plate 110 when the sewage flows. When H3 accounts for 1 / 3 - 2 / 3 of H4, it can ensure that the relatively clear sewage in the upper part passes through, while also blocking solid impurities, improving the sewage discharge efficiency; the length L1 of the pretreatment area 100 is 3 - 5m, the length L2 of the primary biological reaction area 200 is 5 - 8m, the length L3 of the secondary biological reaction area 300 is 0.2 - 0.5m, and the length L4 of the phosphorus and nitrogen conversion area 400 is 10 - 12m. When the sewage passes through each area, it can effectively interact with the fillers or organisms in each area, ensuring the progress rate of the entire sewage discharge process and improving the sewage discharge efficiency.

[0044] In addition, the phosphorus and nitrogen conversion area 400 includes algae 600 and water spinach 700. The algae 600 includes chlorella pyrenoidosa and scenedesmus obliquus. The concentration of chlorella pyrenoidosa is 4.0 - 8.0mg / L, and the concentration of scenedesmus obliquus is 0.5 - 1mg / L; when the concentration of chlorella pyrenoidosa is 4.0 - 8.0mg / L, the removal rates of ammonia nitrogen and nitrite nitrogen can reach over 80% and 75% respectively. When the concentration of scenedesmus obliquus is 0.5 - 1mg / L, the removal rate of nitrite nitrogen can reach over 80%. The water spinach 700 can also remove over 70% of nitrogen and phosphorus in the water and has certain economic value; in addition, planting water spinach can provide habitats and shelters for various aquatic organisms that feed on chlorella, etc., effectively preventing the overgrowth of chlorella, etc.

[0045] This embodiment also provides a physical and biological combined method for treating pond aquaculture sewage, which is realized by using the above-mentioned device. The sewage passes through the pretreatment area 100, the filler area 200, the porous filter screen area 300, and the floating plant area 400 in sequence; the ratio of the water surface height H2 of the sewage to the height H1 of the primary biological reaction filler 211 is (1 - 1.5):1, and the flow rate of the sewage is 12 - 25m / h. When the ratio of H2 to H1 is (1 - 1.5):1, it can effectively make the primary biological reaction filler 211 fully contact with the sewage, improve its utilization rate, and ensure full denitrification when the flow rate of the sewage is 12 - 25m / h, improving the sewage discharge efficiency.

[0046] For testing, in this embodiment, the above-mentioned device is placed at the drainage outlet of a crucian carp pond breeding base. The ammonia nitrogen concentration in the pond drainage can reach 4 mg / L. Water spinach is planted in the biological pond in advance, 4 mg / L of Chlorella vulgaris and 0.5 mg / L of Scenedesmus obliquus are placed, a microbial flocculant is added after the water inlet, and PHBV materials are placed in the reaction tank in advance. The specific process is as follows: The pond drainage enters the pretreatment area 100, where organic substances and impurities in the water are flocculated, and the transparency is greatly improved. Subsequently, the sewage enters the primary biological reaction area 200 and is removed of nitrogen in the water by microbial reactions. After passing through the secondary biological reaction area 300, most of the impurities, COD, and nitrogen and phosphorus concentrations in the water are greatly reduced. After entering the nitrogen and phosphorus conversion area 400, the nitrogen and phosphorus in the water will be continuously consumed by Chlorella vulgaris, water spinach, etc. Finally, the quality of the discharged sewage can meet the national water quality standard of Class IV.

[0047] Embodiment 2

[0048] The implementation method of this embodiment is basically the same as that of Embodiment 1. The main difference lies in: It is installed and placed in a crab pond breeding base lake. The ammonia nitrogen concentration in the pond drainage can reach 5 mg / L, and the effluent is turbid. Water spinach is planted in the biological pond in advance, 5 mg / L of Chlorella vulgaris and 0.75 mg / L of Scenedesmus obliquus are placed, a microbial flocculant and a coagulant aid are added after the water inlet, and PHBV materials are placed in the primary biological reaction area 200 in advance, and K3 annular fillers are placed in the secondary biological reaction area 300. The specific process is as follows: The pond drainage enters the pretreatment area 100, where impurities in the water and pond bottom sediment are flocculated and precipitated, and the transparency is significantly improved. Subsequently, the sewage enters the primary biological reaction area 200 to remove nitrogen and phosphorus nutrients through microorganisms. When passing through the secondary biological reaction area 300, the rich organic matter and suspended substances in the water are intercepted. The nutrients entering the nitrogen and phosphorus conversion area 400 will be continuously consumed by Chlorella vulgaris, water spinach, etc. Finally, the quality of the discharged sewage meets the receiving water body standard.

[0049] The present invention has been described in detail above in connection with specific exemplary embodiments. However, it should be understood that various modifications and variations can be made without departing from the scope of the present invention as defined by the appended claims. The detailed description and the drawings should be considered illustrative only and not restrictive. If there are any such modifications and variations, they will all fall within the scope of the present invention described herein. In addition, the background art is intended to illustrate the research and development status and significance of the present technology and is not intended to limit the present invention or the application fields of the present application and the present invention.

[0050] More specifically, although exemplary embodiments of the present invention have been described herein, the present invention is not limited to these embodiments, but includes any and all embodiments that are recognized by those skilled in the art as being modified, omitted, (e.g., combinations between various embodiments), adaptively changed, and / or substituted based on the foregoing detailed description, and the various embodiments of the present invention can be combined as needed. The limitations in the claims may be broadly interpreted in accordance with the language used in the claims and are not limited to the examples described in the foregoing detailed description or during the implementation of the application, and these examples should be considered non-exclusive. Any steps recited in any method or process claim may be executed in any order and are not limited to the order set forth in the claims. Accordingly, the scope of the present invention should be determined solely by the appended claims and their legal equivalents, rather than by the descriptions and examples given above.

Claims

1. A device for treating pond aquaculture sewage by combining physics and biology, characterized in that, it includes a primary biological reaction zone (200), a phosphorus-nitrogen conversion zone (400) and a secondary biological reaction zone (300); the secondary biological reaction zone (300) is arranged between the primary biological reaction zone (200) and the phosphorus-nitrogen conversion zone (400); a primary biological reaction filler (211) is arranged at the bottom of the primary biological reaction zone (200), a secondary biological reaction filler (303) is arranged in the secondary biological reaction zone (300), the side of the secondary biological reaction zone (300) close to the primary biological reaction zone (200) is a first filter layer (301), and the side of the secondary biological reaction zone (300) close to the phosphorus-nitrogen conversion zone (400) is a second filter layer (302); the first filter layer (301) is made of polyamide fiber with a thickness of 2-4 mm, and the second filter layer (302) is made of activated carbon fiber with a thickness of 5-7 mm.

2. The device for treating pond aquaculture sewage by combining physics and biology according to claim 1, characterized in that, it further includes a pretreatment zone (100), and the pretreatment zone (100) contains a microbial flocculant and a coagulant.

3. The device for treating pond aquaculture sewage by combining physics and biology according to claim 2, characterized in that, the microbial flocculant includes a protein polysaccharide biopolymer flocculant LF-Tou2; and / or the coagulant includes 20-50 mg / L of polyaluminum chloride.

4. The device for treating pond aquaculture sewage by combining physics and biology according to claim 1, characterized in that, the primary biological reaction filler (211) includes a filler with PHBV as the main body, and the secondary biological reaction filler (303) includes a K3 annular filler.

5. The device for treating pond aquaculture sewage by combining physics and biology according to claim 1, characterized in that, the phosphorus-nitrogen conversion zone (400) includes algae (600) and water spinach (700), and the algae (600) includes chlorella pyrenoidosa with a concentration of 4.0-8.0 mg / L and scenedesmus obliquus with a concentration of 0.5-1 mg / L.

6. The device for treating pond aquaculture sewage by combining physics and biology according to claim 2, characterized in that, the length L1 of the pretreatment zone (100) is 3-5 m, the length L2 of the primary biological reaction zone (200) is 5-8 m, the length L3 of the secondary biological reaction zone (300) is 0.2-0.5 m, and the length L4 of the phosphorus-nitrogen conversion zone (400) is 10-12 m.

7. The device for treating pond aquaculture sewage by combining physics and biology according to claim 2, characterized in that, a filter plate (110) is arranged between the pretreatment zone (100) and the primary biological reaction zone (200), a water blocking zone is arranged at the bottom of the filter plate (110), and the height H3 of the water blocking zone accounts for 1 / 3-2 / 3 of the height H4 of the filter plate (110).

8. A physical and biological combined method for treating pond aquaculture sewage, which is realized by using the device described in any one of claims 1 to 7. It is characterized in that the sewage successively passes through a pretreatment area (100), a primary biological reaction area (200), a secondary biological reaction area (300) and a phosphorus and nitrogen conversion area (400).

9. A physical and biological combined method for treating pond aquaculture sewage according to claim 8. It is characterized in that the ratio of the water surface height H2 of the sewage to the height H1 of the primary biological reaction filler (211) is (1 - 1.5):1, and the flow rate of the sewage is 12 - 25 m / h.

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