Circulating water purification soft-shelled turtle breeding system

Abstract

The invention discloses a circulating water purification soft-shelled turtle culture system which comprises a soft-shelled turtle culture pond and a biological water purification module located below the soft-shelled turtle culture pond. The soft-shelled turtle culture pond is provided with an aeration device, a water injection port and a water outlet; the biological water purification module comprises an upper aerobic zone and a lower anaerobic zone which are filled with filler, an upper water guide layer separated by a filter layer is arranged above the aerobic zone, a water distribution device connected with a water outlet of the soft-shelled turtle culture pond is arranged on the upper portion of the upper water guide layer, and a lower water guide layer separated by a filter layer is arranged below the anaerobic zone. A water outlet device connected with a water injection port of the soft-shelled turtle culture pond is arranged in the lower water guide layer, and a one-way exhaust channel and a heating device are arranged in the anaerobic zone. The biological circulation water purification device is arranged by fully utilizing the low-oxygen space below the culture pond and the hydrothermal gradient, and water and water purification cost for soft-shelled turtle culture is greatly saved.

Description

Technical Field

[0001] The present invention relates to the field of aquaculture, and particularly to a circulating water purification soft-shelled turtle farming system. Background Art

[0002] Soft-shelled turtles, also known as Chinese soft-shelled turtles, are aquatic products rich in nutrition, with delicious meat and medicinal value. The farming of soft-shelled turtles mainly adopts two methods: pond farming and greenhouse farming, both of which will produce a large amount of aquaculture wastewater. Especially under greenhouse conditions, due to the relatively high farming density, the water body pollution is more serious, which may affect the vitality of soft-shelled turtles and cause infectious diseases. At present, the cleanliness of the pond water is mainly achieved by regularly draining and changing water, resulting in a large water consumption for soft-shelled turtle farming. Moreover, the discharged wastewater still needs to be further treated before it can be discharged or recycled. The treatment equipment occupies a large amount of space and consumes energy.

[0003] Planting aquatic plants can achieve the self-purification of the water quality in the farming pond, but this method is generally limited to the pond farming mode. In a circulating water purification farming system disclosed in a Chinese Taiwanese invention patent with the authorized publication number TW201808094A, after the aquaculture wastewater is led out of the pond body, it is sent back to the farming pond after being purified by aquatic plants in multiple steps. Although this technical solution does not limit the type of farming pond, the wastewater with a high pollutant concentration is generated in the short term in the greenhouse farming of soft-shelled turtles, and it is impossible to be completely purified by aquatic plants at the same time, and it may also poison the plants. Therefore, a water recycling cycle cannot be formed.

[0004] Microbial technology is an effective means for treating such high-organic-matter, nitrogen, and phosphorus wastewater. Specifically, soft-shelled turtle aquaculture wastewater belongs to typical high-ammonia-nitrogen and low-organic-carbon wastewater, and the C / N ratio is generally lower than 4. The amplification rate of common aerobic microorganisms in it is slow, and the single treatment effect is not good. Anaerobic ammonium oxidation (Anammox) combined with short-cut nitrification can save carbon sources and oxygen supply and produce less sludge compared with traditional full-scale nitrification and denitrification, and it is currently the most promising wastewater biological denitrification technology. However, since high-ammonia-nitrogen wastewater needs to be subjected to short-cut nitrification first before further denitrification, the treatment system still requires a certain degree of aeration, and high temperature (30-40°C) conditions are required to inhibit nitrite-oxidizing bacteria, which brings troubles in terms of site, equipment, and energy. In addition, soft-shelled turtle aquaculture wastewater still has a certain organic carbon content, which will inhibit the activity of anaerobic ammonium oxidation bacteria if not pretreated, and an additional step is also added.

[0005] The optimal farming conditions for soft-shelled turtles are a water temperature of 25-30°C, a dissolved oxygen (DO) in the water body of not less than 5 mg / L, and a pH of about 8, which match the suitable conditions for the wastewater to be treated through the processes of de-organics - short-cut nitrification - anaerobic ammonium oxidation. It is easy to think that using the hydrothermal conditions of the soft-shelled turtle farming pond itself to recycle and treat wastewater can save a large amount of energy and equipment expenses, but it is also necessary to overcome the difficulty of completing multiple steps of treatment in a narrow site. Summary of the Invention

[0006] The present invention aims to provide a circulating water purification turtle farming system, which combines the microbial treatment technology of aerobic decarbonization - shortcut nitrification - anaerobic ammonium oxidation with an underground infiltration scheme to treat turtle farming wastewater, and makes full use of the hydrothermal conditions of the farming pond, saving some equipment and steps for heating and water quality adjustment.

[0007] The present invention discloses a circulating water purification turtle farming system, which includes a turtle farming pond 1 and a biological water purification module 2 located below it;

[0008] The turtle farming pond 1 is provided with an aeration device 3, a water injection port 4 and a drainage port 5;

[0009] The biological water purification module 2 includes an upper aerobic zone 6 filled with fillers and a lower anaerobic zone 7. Above the aerobic zone 6 is an upper water guiding layer 9 separated by a filter layer 8. Above the upper water guiding layer 9 is a water distribution device 10 connected to the drainage port 5. Below the anaerobic zone 7 is a lower water guiding layer 11 separated by a filter layer 8. In the lower water guiding layer 11 is a water outlet device 12 connected to the water injection port 4. A one-way exhaust channel 13 and a heating device 14 are arranged in the anaerobic zone 7;

[0010] The biological water purification module 2 is arranged below the ground, and its bottom wall and side walls are wrapped with heat-insulating and water-proof materials.

[0011] The concept of the present invention is to utilize the infiltration of turtle farming wastewater into the ground due to gravity, and sequentially carry out microbial treatment of aerobic decarbonization, nitritation and anaerobic ammonium oxidation. The environmental conditions required for each step do not need to be completely artificially controlled, but natural gradients of temperature, pH, oxygen concentration, etc. are formed during the infiltration process, so as to achieve the purpose of saving energy, equipment and space costs. Specifically, the suitable temperature for turtle farming water is 25 - 30 °C, pH is 7.5 - 8.5, and DO is not less than 5 mg / L; aerobic organic decomposition bacteria can efficiently and rapidly reduce the chemical oxygen demand (COD) of the wastewater under these conditions, and reduce DO to below 0.5 mg / L, with the pH dropping by about 0.5 units; under the facultative aerobic condition with a pH of about 8.0, ammonia-oxidizing bacteria (AOB) can maintain an absolute population advantage over nitrite-oxidizing bacteria (NOB), enabling partial ammonia nitrogen to be shortcut nitrified and accumulating nitrite; finally, when the dissolved oxygen is completely exhausted, anaerobic ammonium-oxidizing bacteria fully convert nitrite and the remaining ammonia nitrogen into nitrogen gas and discharge it, and the pH rises slightly again. Since the anaerobic part has the highest temperature requirement, the heating device is arranged in the anaerobic zone, forming a temperature and dissolved oxygen gradient decreasing from top to bottom, and a pH gradient decreasing first and then rising, so that the pollutants can be completely removed during the downward infiltration of the farming wastewater due to gravity.

[0012] Furthermore, the packing in the aerobic zone 6 is attached with activated sludge / biofilm with aerobic heterotrophic bacteria as the dominant population, and the packing in the anaerobic zone 7 is attached with activated sludge / biofilm with nitrite bacteria and anaerobic ammonia-oxidizing bacteria as the dominant population. The anaerobic ammonia oxidation process of the present invention is between the one-step (CANON) process and the two-step (SHARON-ANAMMOX) process.

[0013] Preferably, the packing in the aerobic zone 6 is a sandy carrier, and the packing in the anaerobic zone 7 is a loamy carrier. The designed retention time of the soft-shelled turtle breeding wastewater in the aerobic zone 6 is 2 - 4 h, and the designed retention time in the anaerobic zone 7 is 8 - 12 h. In order to reduce the excessive oxidation of ammonia nitrogen in the aerobic zone, it is necessary to minimize the retention time of the wastewater in this area, but also fully remove the organic matter (COD reduced to below 100 mg / L), otherwise it will inhibit the nitrite-anaerobic ammonia-oxidizing bacteria.

[0014] Preferably, the aerobic zone 6 and the anaerobic zone 7 are separated by a fabric, and a water quality monitoring unit 15 is provided at the separation. The water quality monitoring unit 15 at least includes a pH measurement probe and a dissolved oxygen measurement probe. The water quality monitoring unit is mainly responsible for detecting the pH and dissolved oxygen concentration of the wastewater entering the anaerobic zone, and may also include COD.

[0015] More preferably, a water quality measurement and control unit 16 is provided in the water distribution device 10. The water quality measurement and control unit 16 includes a mud retaining grille, a pH measurement probe, a dissolved oxygen measurement probe, a pH adjustment port and an aeration port. The water quality measurement and control unit can be divided into a measurement unit and a control unit. According to the feedback data of the measurement unit and the water quality monitoring unit 15, the pH and DO of the water distribution are adjusted through the control unit. Among them, adjusting DO can also play a role in controlling the consumption rate of organic matter.

[0016] Optionally, the drain outlet 5 is the entire or partial bottom outlet of the soft-shelled turtle breeding pond, and the water distribution device 10 is a percolation layer composed of porous media closely attached to the lower part of the drain outlet 5. This scheme is relatively simple, but some large particle organic matters may be intercepted on one side of the breeding pond, which is not convenient for collection.

[0017] Alternatively, the drain outlet 5 is a hole on the wall of the soft-shelled turtle breeding pond, and the water distribution device 10 is a plurality of perforated pipes buried in the upper part of the upper water guiding layer 9. The perforated pipes are connected to the drain outlet 5 through an extension pipe. This scheme has more uniform water distribution and can better recover the large particle sediments in the wastewater.

[0018] Preferably, the material of the filter layer 8 is non-woven fabric, and the materials of the upper water guiding layer 9 and the lower water guiding layer 11 are gravel or a combination of gravel and limestone.

[0019] Preferably, a disinfection unit 17 is provided in the water outlet device 12, and the disinfectant used in the disinfection unit 17 includes at least one of sodium perborate, sodium thiosulfate, and potassium alum. The effluent after biological treatment may still carry certain impurities such as microorganisms, and the oxygen content is too low, which can be treated with chemical reagents. Optionally, the water injection port 4 is also connected to an external clean water source as a supplement for the loss of circulating purified water.

[0020] Preferably, the bottom of the biological water purification module 2 is provided with a percentage slope (i) not higher than 20%, and the water outlet device 12 is arranged on one side close to the bottom of the slope.

[0021] The beneficial effects of the technical solution of the present invention are as follows:

[0022] 1. In the circulating purified water turtle farming system of the present invention, a biological water purification module is designed below the turtle farming pond, and gravity filtration is used to circulate and treat during the farming process, saving a large amount of time, space, and energy required for sewage treatment in conventional farming methods, and greatly reducing the water consumption of turtle farming.

[0023] 2. In the circulating purified water turtle farming system of the present invention, the microbial population in the biological water purification module gradually changes from aerobic to anaerobic from top to bottom, making full use of the dissolved oxygen, pH, and temperature gradients during the infiltration of the farming wastewater into the ground, and saving the cost of separately regulating the reaction conditions in each treatment area. Description of the Drawings

[0024] Figure 1 is a cross-sectional view of the circulating purified water turtle farming system described in the first embodiment;

[0025] Figure 2 is a cross-sectional view of the circulating purified water turtle farming system described in the second embodiment.

[0026] In the figure: 1 is a turtle farming pond, 2 is a biological water purification module, 3 is an aeration device, 4 is a water injection port, 5 is a drain port, 6 is an aerobic zone, 7 is an anaerobic zone, 8 is a filter layer, 9 is an upper water guiding layer, 10 is a water distribution device, 11 is a lower water guiding layer, 12 is a water outlet device, 13 is a one-way exhaust channel, 14 is a heating device, 15 is a water quality monitoring unit, 16 is a water quality measurement and control unit, and 17 is a disinfection unit. Detailed Embodiments

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described below in conjunction with embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention and should not be regarded as a limitation of the present invention.

[0028] As Figure 1As shown in the figure, in the first embodiment of the present invention, a circulating water purification soft-shelled turtle farming system is composed of a soft-shelled turtle farming pond 1 and a biological water purification module 2 located below the ground under it. The soft-shelled turtle farming pond 1 is provided with an aeration device 3, a water injection port 4 and a drainage port 5. The biological water purification module 2 includes an upper aerobic zone 6 and a lower anaerobic zone 7 separated by a fabric, and a water quality monitoring unit 15 is provided at the separation; above the aerobic zone 6 is an upper water guiding layer 9 separated by a filter layer 8, and a water distribution device 10 connected to the drainage port 5 is provided above the upper water guiding layer 9, and a water quality measurement and control unit 16 is provided in the water distribution device 10; below the anaerobic zone 7 is a lower water guiding layer 11 separated by a filter layer 8, and a water outlet device 12 connected to the water injection port 4 is provided in the lower water guiding layer 11, and a disinfection unit 17 is provided in the water outlet device 12, and a one-way exhaust channel 13 and a heating device 14 are arranged in the anaerobic zone 7. The material of the filter layer 8 is non-woven fabric, and the materials of the upper water guiding layer 9 and the lower water guiding layer 11 are gravel and limestone.

[0029] It should be noted that in this embodiment, the drainage port 5 is the entire bottom port of the soft-shelled turtle farming pond, and the water distribution device 10 is a percolation layer composed of fine sandy loam closely attached to the lower part of the drainage port 5. During the period of injecting water to farm soft-shelled turtles, the farming water seeps through the percolation layer at an almost constant rate (6 - 10 cm / d) and is evenly distributed into the aerobic zone through the upper water guiding layer, and the 50-cm-deep farming water is completely replaced once within 5 - 9 days.

[0030] In this embodiment, the aerobic zone 6 is filled with sandy loam soil containing aerobic activated sludge; the anaerobic zone 7 is filled with fine loam soil containing nitrosomonas, anaerobic ammonium-oxidizing bacteria and a small amount of polyphosphate-accumulating bacteria. Under the water-saturated state, it takes 3 hours for the wastewater to pass through the aerobic zone and 10 hours to pass through the anaerobic zone.

[0031] Since the biological water purification module is located underground and its bottom wall and side walls are wrapped with heat-insulating and water-proof materials, a suitable temperature with a small gradient can be obtained with a relatively low heating power. In actual use, the temperature of the anaerobic zone is 30 - 35 °C, the temperature of the aerobic zone is 28 - 32 °C, and the water temperature of the farming pond is 25 - 30 °C; no additional temperature control is required in summer, and an additional heating device can be connected to the farming pond in winter.

[0032] The pH of the wastewater first decreases and then increases with the height reduction in the biological water purification module. The recommended scheme in actual operation is that the pond water of the soft-shelled turtle farming pond with a pH of 8.2 - 8.5 enters the aerobic zone, the pH drops to 7.7 - 8.2 and enters the anaerobic zone, and the final effluent pH is about 8.5. Generally, no additional pH adjustment is required, but since pH has a great influence on the wastewater treatment microorganisms, a pH adjustment port is still provided in the water distribution device.

[0033] The dissolved oxygen concentration in the aquaculture water decreases with the decrease in height. In actual operation, the recommended scheme is that the average dissolved oxygen concentration in the water of the soft-shelled turtle aquaculture pond is 6 - 12 mg / L. When it enters the aerobic zone, it drops to 3 - 5 mg / L due to passing through the filter layer, and when it enters the anaerobic zone, it drops to 0.3 - 0.7 mg / L. Generally, there is no need to additionally adjust the dissolved oxygen in the biological water purification module, but a dissolved oxygen adjustment port is still provided in the water distribution device.

[0034] In contrast, adult soft-shelled turtles of the same number are cultured in greenhouse aquaculture ponds of the same size and depth, and one-third of the pond water is replaced every 3 days according to the conventional aquaculture method. In the first embodiment of the present invention, the water injection port 4 is also connected to an external clean water source (not shown in the figure), only supplementing the water loss in the circulation. The consumption of clean water is reduced by 86% compared with the conventional method. By detecting the aquaculture water flowing through the drain port 5 and the water outlet device 12, it is found that after passing through the biological water purification module, the COD is reduced by 74% (which can be further removed in the disinfection unit), and the total nitrogen is reduced by 91.7%, with remarkable water purification effect.

[0035] As Figure 2 shown, in the second embodiment of the present invention, the circulating water purification soft-shelled turtle aquaculture system has the same components and connection relationships as the first embodiment. The difference is that in this embodiment, the drain port 5 is a hole on the wall of the soft-shelled turtle aquaculture pond, and the water distribution device 10 is a plurality of perforated pipes (only one is shown in the figure) buried above the upper water conduction layer 9. The perforated pipes are connected to the drain port 5 through an extended pipe. In addition to the advantages mentioned above, a valve can be added to the extended pipe in the technical solution of this embodiment to control the amount of aquaculture water entering the water purification system; the advantage of this design is that the treatment can be carried out after the organic matter and ammonia nitrogen in the pond water accumulate to a higher value, which is conducive to the amplification of the microbial population.

[0036] In addition, a 10% percentage slope (i) is provided at the bottom of the biological water purification module 2 in the second embodiment, and the water outlet device 12 is arranged on one side close to the bottom of the slope, facilitating the recovery of the purified water.

[0037] The circulating water purification soft-shelled turtle aquaculture system described in the first embodiment has a cubic appearance, and the cross-sections of the soft-shelled turtle aquaculture pond and the biological water purification module coincide; while the circulating water purification soft-shelled turtle aquaculture system described in the second embodiment has a cylindrical appearance, and the cross-section of the biological water purification module is larger than and completely includes the cross-section of the soft-shelled turtle aquaculture pond. For the present invention, the shapes and sizes of the soft-shelled turtle aquaculture pond and the biological water purification module are not limited, but should preferably meet the conditions of facilitating the uniform penetration of wastewater and the uniform thermal gradient as much as possible, and the size of the biological water purification module determines the upper limit of the number of soft-shelled turtles that the aquaculture pond can carry.

[0038] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description, and the obvious changes or variations derived therefrom should still be regarded as the protection scope of the present invention.

Claims

1. A circulating water purification soft-shell turtle breeding system, characterized in that: It comprises a turtle breeding pond (1) and a biological water purification module (2) located below the pond; The turtle breeding pond (1) is provided with an aeration device (3), a water injection port (4) and a drainage port (5); The biological water purification module (2) comprises an upper aerobic zone (6) filled with fillers and a lower anaerobic zone (7); an upper water-conducting layer (9) separated by a filter layer (8) is located above the aerobic zone (6); a water distribution device (10) connected to a drain port (5) is provided at the upper part of the upper water-conducting layer (9); a lower water-conducting layer (11) separated by a filter layer (8) is located below the anaerobic zone (7); a water outlet device (12) connected to a water injection port (4) is provided in the lower water-conducting layer (11); and a one-way exhaust passage (13) and a heating device (14) are provided in the anaerobic zone (7); The biological water purification module (2) is arranged below the ground, and its bottom wall and side walls are wrapped with heat-insulating and waterproof materials.

2. The circulating water purification turtle breeding system according to claim 1 is characterized in that: The filler of the aerobic zone (6) is attached with activated sludge / biofilm with aerobic heterotrophic bacteria as the dominant species, and the filler of the anaerobic zone (7) is attached with activated sludge / biofilm with nitrite bacteria and anaerobic ammonia oxidizing bacteria as the dominant species.

3. The circulating water purification turtle breeding system according to claim 2 is characterized in that: The filler of the aerobic zone (6) is a sand carrier, and the filler of the anaerobic zone (7) is a soil carrier. The residence time of the turtle breeding wastewater in the aerobic zone (6) is 2 to 4 hours, and the residence time in the anaerobic zone (7) is 8 to 12 hours.

4. The circulating water purification turtle breeding system according to any one of claims 1 to 3, characterized in that: The aerobic zone (6) and the anaerobic zone (7) are separated by fabric, and a water quality monitoring unit (15) is provided at the separation point. The water quality monitoring unit (15) comprises at least a pH measuring probe and a dissolved oxygen measuring probe.

5. The circulating water purification turtle breeding system according to claim 4 is characterized in that: The water distribution device (10) is provided with a water quality measurement and control unit (16), which comprises a mud retaining grid, a pH measurement probe, a dissolved oxygen measurement probe, a pH adjustment port and an aeration port.

6. The circulating water purification turtle breeding system according to claim 5, characterized in that: The drainage outlet (5) is the entire or part of the bottom of the turtle breeding pond, and the water distribution device (10) is a percolation layer composed of porous media and is closely attached to the lower part of the drainage outlet (5).

7. The circulating water purification turtle breeding system according to claim 5, characterized in that: The drain outlet (5) is a hole on the wall of the turtle breeding pond, and the water distribution device (10) is a plurality of perforated pipes buried in the upper part of the upper water-conducting layer (9), and the perforated pipes are connected to the drain outlet (5) through an extension pipe.

8. The circulating water purification turtle breeding system according to claim 1 is characterized in that: The material of the filter layer (8) is non-woven fabric, and the materials of the upper water-conducting layer (9) and the lower water-conducting layer (11) are gravel or a combination of gravel and limestone.

9. The circulating water purification turtle breeding system according to claim 1, characterized in that: The water outlet device (12) is provided with a disinfection unit (17), and the disinfectant used by the disinfection unit (17) includes at least one of sodium perborate, sodium thiosulfate, and potassium aluminum sulfate.

10. The circulating water purification turtle breeding system according to claim 1, characterized in that: The bottom of the biological water purification module (2) is provided with a percentage slope of no more than 20%, and the water outlet device (12) is arranged on a side close to the bottom of the slope.

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