A new type of biological treatment process and device for marine aquaculture tail water

Abstract

The present invention relates to a novel biological treatment process and device for seawater aquaculture tailwater, belonging to the technical field of aquaculture tailwater treatment. The process flow is as follows: mechanical filtration system → protein separation system → aerobic nitrification conversion system → anaerobic denitrification conversion system → COD reduction system → disinfection and oxygenation system. The systems are interconnected through transmission pipelines, and the physical and chemical conditions are different. Since nitrifying bacteria and denitrifying bacteria screened from the bottom mud of seawater aquaculture ponds are used, they are suitable for the growth of specific microorganisms and improve the biological conversion rate of aquaculture tailwater; at the same time, the microbial attachment base pressed by renewable materials is variable in shape and low in cost. The present invention can greatly improve the treatment efficiency of seawater aquaculture tailwater, improve the utilization rate of seawater resources, reduce the adverse effects of seawater aquaculture on the environment, and the reuse rate of aquaculture tailwater can be increased by more than 15%. It also has the advantages of simple process and convenient maintenance.

Description

Technical Field

[0001] The present invention relates to a novel biological treatment process for seawater aquaculture tail water, in particular to a process and device for treating seawater aquaculture tail water by using different kinds of microorganisms, thereby improving the recycling rate of aquaculture water, and belongs to the technical field of aquaculture tail water treatment. Background Art

[0002] Large-scale discharge and release is still the main way of using water in my country's seawater ponds and factory aquaculture. Aquaculture effluent contains a large amount of feces and uneaten feed of farmed organisms. Aquaculture effluent is discharged into the environment, endangering the surrounding ecology.

[0003] The treatment of aquaculture tailwater mainly exists in the closed-loop aquaculture model. The core of the process is based on the transamination of biological contact oxidation, using nitrifying bacteria to convert ammonia nitrogen and nitrite nitrogen into nitrate nitrogen under aerobic conditions. The efficiency of water treatment is extremely related to the material, properties of the nitrifying bacteria attachment base, and the species and density of the attached bacteria. In some aquaculture systems with better tailwater treatment technology, the reuse rate of tailwater can reach more than 90%. The nitrifying bacteria and denitrifying bacteria in the existing aquaculture tailwater treatment process rely on natural selection and natural growth. The species, density and growth conditions are non-selective, and there is no clear dividing line between nitrification and denitrification processes. The treatment process is unclear, the nitrification and denitrification efficiency is low, and a larger microbial attachment base is required, thereby increasing the cost of water treatment.

[0004] In addition, with the continuous reuse of aquaculture tail water, nitrate nitrogen and COD in the water will accumulate higher and higher, which will eventually reduce the water's usability and affect its reuse. Currently, no denitrification device or COD reduction device is involved in the treatment of marine aquaculture tail water. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the above-mentioned prior art and provide a new type of marine aquaculture tailwater biological treatment process, which divides the water treatment system into aerobic nitrification zone, anaerobic denitrification zone and COD reduction zone by adjusting the physical and chemical environment of the water treatment system. The zones are interconnected and have different physical and chemical conditions, which are suitable for the growth of specific microorganisms and improve their biological conversion rate; at the same time, the microbial attachment base pressed by renewable materials is variable in shape and low in cost. In addition, the present invention uses nitrifying bacteria and denitrifying bacteria screened from the bottom mud of marine aquaculture ponds, which have strong specificity and high biological conversion rate, can greatly improve the treatment efficiency of marine aquaculture tailwater, improve the utilization rate of seawater resources, reduce the adverse effects of marine aquaculture on the environment, and have the advantages of simple process and convenient maintenance.

[0006] The present invention is achieved through the following technical solutions:

[0007] A novel biological treatment process for marine aquaculture tail water includes a mechanical filtration system, a protein separation system and a disinfection and oxygenation system. The special feature of the process is that an aerobic nitrification conversion system, an anaerobic denitrification conversion system and a COD reduction system are also provided. The systems are connected by pipelines. The aquaculture tail water first passes through a mechanical filtration system to remove suspended solids in the tail water by physical filtration, then enters a protein separation system, and uses a protein separator to remove soluble organic matter in the tail water. Then, the aquaculture tail water is converted into ammonia nitrogen and nitrite nitrogen into nitrate nitrogen in the aerobic nitrification conversion system, and then enters an anaerobic denitrification system to convert nitrate nitrogen into nitrogen gas under anaerobic conditions and discharge it into the air. Then, the tail water enters a COD reduction system to reduce the COD in the tail water, and finally enters a disinfection and oxygenation system.

[0008] The aerobic nitrification conversion system is a device that converts ammonia nitrogen and nitrite nitrogen in aquaculture tail water into nitrate nitrogen. The system is divided into four independent areas in sequence, namely, the initial contact area, the intensive reaction area, the buffer area and the pH adjustment area. The bottom of the first three areas are provided with aerated stones and air pipes, and then microbial attachment bases are piled up on the aerated stones and air pipes. The direction of the water pipes in the microbial attachment base is parallel to the direction of the water flow. The microbial attachment bases in the initial reaction area, the intensive reaction area and the buffer area are placed in an outward-extending trapezoidal shape, and no microbial attachment bases and aerated stones are placed in the pH adjustment area. The tail water treatment volume capacity of this system accounts for 6 / 10 to 7 / 10 of the total water treatment system.

[0009] When the system is working, firstly, the cultured nitrifying bacteria (10 9 cfu / ml) is diluted 1000 times with seawater and sprinkled on the microbial attachment base. The initial addition amount of the dilution is 0.2% of the treated water volume per unit time, and then filled with aquaculture tail water. During this period, the water temperature is maintained above 15°C and aeration (air) is maintained for more than 5 days. After that, NaOH is used to adjust the pH in the pH adjustment area to 8.5≤pH≤10.

[0010] The nitrifying bacteria screened by inoculation culture are based on nitrifying bacteria separated from the bottom mud of seawater ponds as the original strains, which are freeze-dried after fermentation and expansion culture. The separation method is conventional plate coating and streak culture method. After separation, 16s rRNA is identified as the corresponding strain.

[0011] The anaerobic denitrification conversion system is a device that converts nitrate nitrogen in aquaculture tail water into nitrogen gas. The device enables denitrifying bacteria to convert nitrate nitrogen into nitrogen gas under anaerobic conditions and discharge it into the air. The system requires that the microbial attachment base be accumulated in the system, and the direction of the water pipe in the microbial attachment base is parallel to the direction of water flow. The tail water treatment volume capacity of the system accounts for 2 / 10 to 3 / 10 of the total water treatment system volume.

[0012] When the system is running, the cultured denitrifying bacteria (10 9cfu / ml) is diluted 1000 times with seawater and sprinkled on the microbial attachment base. The initial addition amount of the dilution is 0.2% of the treated water volume per unit time. Then it is filled with the aquaculture tail water after the previous stage of treatment. During this period, the water temperature is kept above 15℃. Aeration is strictly prohibited and it should be maintained for more than 3 days.

[0013] The denitrifying bacteria are high-salt-tolerant denitrifying bacteria separated from the bottom mud of a marine aquaculture pond. The separation method is conventional plate coating and streak culture method. After separation, the bacteria are identified as corresponding species by 16S rRNA.

[0014] The anaerobic environment is achieved by removing the aeration stones in the system and relying on the oxygen consumption of nitrifying bacteria.

[0015] The COD reduction system is a device for reducing COD in aquaculture tail water. When the system is constructed, bottom aerated stones and air pipes are first arranged, and then microbial attachment bases are piled up. The tail water treatment volume capacity of the system accounts for 1 / 10 to 2 / 10 of the total water treatment system volume.

[0016] When the system is running, the composite microorganisms (10 9 cfu / ml) was diluted 1000 times and sprinkled on the microbial attachment base. The initial addition amount of the dilution was 0.5% of the treated water volume per unit time, and then the aquaculture tail water after the previous stage of treatment was added.

[0017] The composite microorganism is composed of high-salt-tolerant Bacillus subtilis and Enterococcus faecalis, and the biomass ratio of the two is 1:1.

[0018] The microbial attachment bases described in the above-mentioned systems are all customized microbial attachment bases, which are pressed from renewable composite plastic materials. Their shapes and sizes are customized according to the shape requirements of each system. The main body of the microbial attachment base is in the shape of a honeycomb tube. The inner diameter of the tube can be adjusted according to the tail water treatment volume capacity of each system, generally between 1 and 5 cm. The tail water treatment volume per unit time is proportional to the inner diameter of the tube. The water pipe in the attachment base is parallel to the direction of water flow. The microbial attachment base can be formed by stacking several unit modules, or it can be customized in an integrated manner according to the shape of the system. The integrated microbial attachment base can reduce the collision and wear between the attachment bases in water treatment, and at the same time form a fixed water flow channel, so that the water flow is smooth and the bacteria and water are in full contact, which is conducive to the biological transformation of microorganisms.

[0019] The capacity volume ratio of the above-mentioned three water treatment systems, namely, the aerobic nitrification system, the anaerobic denitrification system and the COD reduction system, is (6~7):(2~3):(1~2).

[0020] The marine aquaculture tailwater biological treatment device of the present invention has a treatment efficiency of aquaculture tailwater that is proportional to the contact time of the microorganism attachment base and the amount of the attachment base added, that is, the more attachment bases are added and the longer the contact time is, the higher the treatment efficiency is.

[0021] Compared with the prior art, the present invention has the following characteristics:

[0022] 1. By controlling dissolved oxygen, pH, and dominant microorganisms, the water treatment system is divided into clearly defined nitrification reaction zones, denitrification reaction zones, and COD reaction zones. Each zone is interconnected and has different physical and chemical conditions, which are suitable for the growth of specific microorganisms and improve their biological conversion rate.

[0023] 2. The use of renewable plastics to press the microbial attachment base greatly reduces the system cost on the one hand, and on the other hand, the size and shape of the attachment base can be customized according to the shape of the water treatment system. The integrated microbial attachment base can reduce the collision and wear between the attachment bases during water treatment, and at the same time form a fixed water flow channel, so that the water flow is smooth and the bacteria and water are in full contact, which is conducive to the biological transformation of microorganisms.

[0024] 3. The nitrifying bacteria and denitrifying bacteria isolated from the bottom mud of seawater aquaculture ponds are selected as the initial inoculation strains. On the one hand, it shortens the time for the corresponding strains to form dominant bacterial communities, and on the other hand, it improves the biological treatment efficiency of the strains.

[0025] 4. Calculated based on the ratio of aquaculture water volume to treated water volume of 2:1, the tail water treatment volume capacity of the aerobic nitrification conversion system accounts for 6~7 / 10 of the total water treatment system volume, the tail water treatment volume capacity of the anaerobic denitrification system accounts for 2~3 / 10 of the total water treatment system volume, and the tail water treatment volume capacity of the COD reduction system accounts for about 1~2 / 10 of the total water treatment system volume; calculated based on the water treatment process time, the nitrification reaction time accounts for about 7 / 10 of the total water treatment time, the denitrification reaction accounts for about 2 / 10 of the water treatment time, and the COD reduction reaction accounts for about 1 / 10 of the water treatment time.

[0026] 5. Under certain conditions (water temperature 10~30℃, pH around 8 in nitrification reaction zone and COD reduction zone, dissolved oxygen ≥6mg / L, pH above 8.5 in denitrification reaction zone, dissolved oxygen ≤2mg / L, salinity ≥20), the efficiency of tailwater biological treatment is proportional to the treatment time and the volume of microbial attachment base.

[0027] The present invention uses nitrifying bacteria and denitrifying bacteria screened from the bottom mud of seawater aquaculture ponds, which have strong specificity and high bioconversion rate, can greatly improve the treatment efficiency of seawater aquaculture tail water, improve the utilization rate of seawater resources, reduce the adverse effects of seawater aquaculture on the environment, and the reuse rate of aquaculture tail water can be increased by more than 15%. It also has the advantages of simple process and convenient maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 : is a process flow chart of biological treatment of marine aquaculture tail water of the present invention;

[0029] Figure 2 : It is a top view schematic diagram of the aerobic nitrification conversion system;

[0030] Figure 3 : It is a cross-sectional schematic diagram of the aerobic nitrification conversion system;

[0031] Figure 4 : Schematic diagram of the anaerobic denitrification system from top view;

[0032] Figure 5 : It is a cross-sectional diagram of the anaerobic denitrification system;

[0033] Figure 6 : Schematic diagram of the COD reduction system from top view;

[0034] Figure 7 : Schematic diagram of the COD reduction system cross section;

[0035] Figure 8 : Schematic diagram of biological water treatment for circulating aquaculture before transformation;

[0036] Fig. 9 : Schematic diagram of biological water treatment for circulating aquaculture after transformation;

[0037] Fig.10 : Schematic diagram of the cross section of the aerobic nitrification conversion system, the anaerobic denitrification conversion system, and the COD reduction system;

[0038] Fig.11 : Schematic diagram of the structure of microbial attachment base;

[0039] In the figure: 1. Microbial attachment base, 2. Inflatable stone; A. Initial contact area, B. Intensive reaction area, C. Buffer zone, D. pH adjustment area; a. Water collection channel, b. Air flotation machine, c. Biological water treatment system, d. Temperature controller, e. High-level pool, f. Breeding pool, g. Management room; III. Aerobic nitrification conversion system, IV. Anaerobic denitrification conversion system, V. COD reduction system. DETAILED DESCRIPTION

[0040] The following is a specific implementation of the present invention with reference to the accompanying drawings to further illustrate the composition of the present invention.

[0041] Example 1

[0042] The biological treatment process of the tail water of seawater aquaculture in this embodiment is shown in the attached figure. Figure 1As shown, it includes a mechanical filtration system, a protein separation system and a disinfection and oxygenation system. It is characterized in that it is also equipped with an aerobic nitrification conversion system, an anaerobic denitrification conversion system and a COD reduction system. The systems are connected by liquid conveying pipelines. The aquaculture tail water first passes through the mechanical filtration system to remove solid suspended matter in the tail water by physical filtration, and then enters the protein separation system to remove soluble organic matter in the tail water by a protein separator. Then, the aquaculture tail water converts ammonia nitrogen and nitrite nitrogen into nitrate nitrogen in the aerobic nitrification conversion system, and then enters the anaerobic denitrification conversion system to convert nitrate nitrogen into nitrogen gas under anaerobic conditions and discharge it into the air. Then, it enters the COD reduction system to reduce the COD in the tail water, and finally enters the disinfection and oxygenation system to realize the recycling of aquaculture water.

[0043] The aerobic nitrification conversion system is a device that converts ammonia nitrogen and nitrite nitrogen in aquaculture tail water into nitrate nitrogen. Its structural diagram is shown in the attached figure. Figure 2 , 3 As shown, the system is divided into four independent areas in sequence, namely, initial contact area A, intensive reaction area B, buffer area C and pH adjustment area D. Inflatable stones 2 and air tubes are arranged at the bottom of the first three areas, and then microbial attachment bases 1 are stacked on the inflatable stones and air tubes in sequence. The direction of the water pipes in the microbial attachment base 1 is parallel to the direction of water flow. The microbial attachment bases in the initial reaction area, intensive reaction area and buffer area are arranged in an outward-extended trapezoid. No microbial attachment bases and inflatable stones are placed in the pH adjustment area. The tail water treatment volume capacity of this system accounts for 7 / 10 of the total water treatment system.

[0044] When the system is working, firstly, the cultured nitrifying bacteria (10 9 cfu / ml) was diluted 1000 times with seawater and sprinkled on the microbial attachment base 1. The initial total amount of the dilution added was 0.2% of the treated water volume per unit time. Then it was filled with aquaculture tail water. During this period, the water temperature was kept above 15°C and aeration (air) was maintained for 6 days. After that, NaOH was used to adjust the pH to 8.5 in the pH adjustment area.

[0045] The nitrifying bacteria screened by inoculation culture are based on nitrifying bacteria separated from the bottom mud of seawater ponds as the original strains, which are freeze-dried after fermentation and expansion culture. The separation method is conventional plate coating and streak culture method, and after separation, they are identified as corresponding strains by 16SrRNA.

[0046] The anaerobic denitrification conversion system is a device that converts nitrate nitrogen in aquaculture tail water into nitrogen gas. The device enables denitrifying bacteria to convert nitrate nitrogen into nitrogen gas under anaerobic conditions and discharge it into the air. The system requires that the microbial attachment base 1 be accumulated in the system, and the direction of the water pipe in the microbial attachment base is parallel to the direction of water flow. The tail water treatment volume capacity of the system accounts for 2 / 10 of the total water treatment system volume. Its structure is shown in the attached figure. Figure 4 , 5 shown.

[0047] When the system is running, the cultured denitrifying bacteria (10 9 cfu / ml) was diluted 1000 times with seawater and sprinkled on the microbial attachment base 1. The initial total amount of the dilution added was 0.2% of the treated water volume per unit time. Then it was filled with the aquaculture tail water after the previous stage of treatment. During this period, the water temperature was kept above 15°C and aeration was strictly prohibited. It was maintained for 3 days.

[0048] The denitrifying bacteria are high-salt-tolerant denitrifying bacteria separated from the bottom mud of a marine aquaculture pond. The separation method is conventional plate coating and streak culture method. After separation, the bacteria are identified as corresponding species by 16S rRNA.

[0049] The anaerobic environment is achieved by removing the aeration stones from the system and relying on the consumption of oxygen by nitrifying bacteria.

[0050] The COD reduction system is a device that reduces the COD in aquaculture tail water. Its structural diagram is shown in the attached figure. Figure 6 , 7 As shown, when the system is constructed, the bottom aerated stone 2 and the air pipe are arranged first, and then the microbial attachment base 1 is piled up. The tail water treatment volume capacity of the system accounts for 1 / 10 of the total water treatment system volume.

[0051] When the system is running, the composite microorganisms (10 9 cfu / ml) was diluted 1000 times and sprinkled on the microbial attachment base 1. The initial addition amount of the diluent was 0.5% of the treated water volume per unit time, and then the aquaculture tail water after the previous stage of treatment was added.

[0052] The composite microorganism is composed of high-salt-tolerant Bacillus subtilis and Enterococcus faecalis, and the biomass ratio of the two is 1:1.

[0053] The microbial attachment bases used in the above systems are all customized microbial attachment bases, which are pressed from renewable composite plastic materials. Their shapes and sizes are customized according to the shape requirements of each system. The main body of the microbial attachment base is in the shape of a honeycomb tube. The inner diameter of the tube can be adjusted according to the volume and capacity of the tail water treatment of each system, generally between 1 and 5 cm. The water pipe in the microbial attachment base is parallel to the direction of water flow. The microbial attachment base is composed of several unit modules. The schematic diagram of the microbial attachment base structure is shown in the attached figure. Fig.11 shown.

[0054] The capacity volume ratio of the three water treatment subsystems, aerobic nitrification system, anaerobic denitrification system and COD reduction system, is 7:2:1.

[0055] Example 2

[0056] This embodiment is a process flow of biological treatment of marine aquaculture tail water provided by the present invention, and the tail water treatment system of a circulating aquaculture workshop in Dongying, Shandong Province was transformed in 2019. The schematic diagram of the biological water treatment of circulating aquaculture before the transformation is shown in the attached figure. Figure 8 As shown, the aquaculture water body of this aquaculture workshop is 384m 3 , tailwater treatment capacity is 96m 3 / h, daily water replenishment 320m 3 In this tail water treatment process, the nitrification process and the denitrification process are mixed together. Since the nitrification process consumes a lot of oxygen, the denitrification process is mainly responsible, which seriously limits the efficiency of biological contact oxidation. After multiple cycles of aquaculture water, a lot of nitrate nitrogen and COD accumulate in the water body, affecting the recycling rate of aquaculture water.

[0057] The schematic diagram of the recirculating aquaculture biological water treatment after transformation is as attached. Fig. 9 As shown, the aquaculture tail water flows from the aquaculture pond f through the water collection channel a, enters the flotation machine b for filtration to remove suspended solids in the tail water, and then enters the biological water treatment system, adding aerobic nitrification system III, anaerobic denitrification system IV and COD reduction system V. The volume of aerobic nitrification system: the volume of anaerobic denitrification system: the volume of COD reduction system = 7:2:1. After the biological treatment is completed, the tail water enters the temperature controller, and the water body is temperature-controlled and reused.

[0058] Aerobic nitrification conversion system III is divided into four independent areas: initial contact area, intensive reaction area, buffer area and pH adjustment area. Aerated stones and air tubes are arranged at the bottom of the first three areas, and then microbial attachment bases are piled up on the aerated stones and air tubes. The direction of the water pipes in the microbial attachment bases is parallel to the direction of water flow. Microbial attachment bases are placed in the initial reaction area, intensive reaction area and buffer area, while microbial attachment bases and aerated stones are not placed in the pH adjustment area. The tail water treatment volume capacity of this system accounts for 7 / 10 of the total water treatment system.

[0059] When the system is working, firstly culture the nitrifying bacteria (10 9 cfu / ml) is diluted 1000 times with seawater and sprinkled on the microbial attachment base. The initial addition amount of the dilution is 0.2% of the treated water volume per unit time, and then filled with aquaculture tail water. During this period, the water temperature is maintained above 15°C and aeration (air) is maintained for more than 5 days. After that, NaOH is used to adjust the pH in the pH adjustment area to 8.5≤pH≤10.

[0060] The nitrifying bacteria used are nitrifying bacteria separated from the bottom mud of seawater ponds as the original strains, which are freeze-dried after fermentation and expansion culture. The separation method is conventional plate coating and streak culture method. After separation, the corresponding strains are identified by 16S rRNA.

[0061] Anaerobic denitrification conversion system IV converts nitrate nitrogen in aquaculture tail water into nitrogen gas. This system enables denitrifying bacteria to convert nitrate nitrogen into nitrogen gas under anaerobic conditions and discharge it into the air. It is required that the microbial attachment base 1 be accumulated in the system, and the direction of the water pipe in the microbial attachment base is parallel to the direction of water flow. The tail water treatment volume capacity of this system accounts for 2 / 10 of the total water treatment system volume.

[0062] When the system is running, the cultured denitrifying bacteria (10 9 cfu / ml) was diluted 1000 times with seawater and sprinkled on the microbial attachment base 1. The initial total amount of the dilution added was 0.2% of the treated water volume per unit time. Then it was filled with the aquaculture tail water after the previous stage of treatment. During this period, the water temperature was kept above 15°C and aeration was strictly prohibited. It was maintained for 3 days.

[0063] The denitrifying bacteria used are high-salt-tolerant denitrifying bacteria isolated from the bottom mud of marine aquaculture ponds. The isolation method is conventional plate coating and streak culture method. After isolation, the corresponding bacterial species are identified by 16S rRNA.

[0064] The anaerobic environment is achieved by removing the aeration stones from the system and relying on the consumption of oxygen by nitrifying bacteria.

[0065] The COD reduction system V is a device for reducing COD in aquaculture tail water. When the system is constructed, the bottom aerated stone 2 and the air pipe are arranged first, and then the microbial attachment base 1 is piled up. The tail water treatment volume capacity of the system accounts for 1 / 10 of the total water treatment system volume.

[0066] When the system is running, the composite microorganisms (10 9 cfu / ml) was diluted 1000 times and sprinkled on the microbial attachment base 1. The initial addition amount of the diluent was 0.5% of the treated water volume per unit time, and then the aquaculture tail water after the previous stage of treatment was added.

[0067] The composite microorganisms used are composed of high-salt-tolerant Bacillus subtilis and Enterococcus faecalis, and the biomass ratio of the two is 1:1.

[0068] The microbial attachment bases used in each system are customized microbial attachment bases, which are pressed from renewable composite plastic materials. The microbial attachment bases are customized according to the shape of each system. The main body is in the shape of a honeycomb tube. The inner diameter of the tube can be adjusted according to the volume and capacity of the tail water treatment of each system, between 1 and 5 cm. The water pipe in the microbial attachment base is parallel to the direction of water flow. The integrated microbial attachment base can reduce the collision and wear between the attachment bases in water treatment, and at the same time form a fixed water flow channel, with smooth water flow and sufficient contact between bacteria and water, which is conducive to the biological transformation of microorganisms.

[0069] After the transformation of the tailwater treatment system of the breeding workshop, the comprehensive tailwater treatment capacity is still 96m3 / h, the daily water replenishment can be reduced to 80 m 3 , greatly reducing the average daily water replenishment, saving water, and reducing the adverse impact of marine aquaculture on the environment.

[0070] The present invention is also suitable for centralized treatment of tailwater in modern fishery breeding areas. After the tailwater of each breeding unit is collected, 2 to 3 breeding treatment systems are set according to the tailwater volume. Each breeding system is composed of aerobic nitrification, anaerobic denitrification and COD reduction modules. The water treated by each system is merged through a pipeline and reused or discharged.

[0071] Attached Fig.10 The schematic cross-sectional diagram of the aerobic nitrification conversion system III, the anaerobic denitrification conversion system IV, and the COD reduction system V is shown, wherein the volume ratio of each device can be adjusted according to the nitrate content in the local water body.

[0072] The embodiments listed above are only preferred implementation modes of the present invention. The protection scope of the present invention is not limited to the embodiments given above. All technical solutions that can be implemented according to the ideas of the present invention belong to the protection scope of the present invention.

Claims

1. A novel biological treatment process for marine aquaculture tail water, comprising a mechanical filtration system, a protein separation system and a disinfection and oxygenation system, characterized in that There are also aerobic nitrification conversion system, anaerobic denitrification conversion system and COD reduction system. The systems are connected through transmission pipelines. The aquaculture tail water first passes through the mechanical filtration system to remove the solid suspended matter in the tail water by physical filtration, and then enters the protein separation system to remove the soluble organic matter in the tail water by protein separator. Then the aquaculture tail water converts ammonia nitrogen and nitrite nitrogen into nitrate nitrogen in the aerobic nitrification system, and then enters the anaerobic denitrification system to convert nitrate nitrogen into nitrogen gas under anaerobic conditions and discharge it into the air. Then it enters the COD reduction system to reduce the COD in the tail water, and finally enters the disinfection and oxygenation system. The aerobic nitrification conversion system is a device for converting ammonia nitrogen and nitrite nitrogen in aquaculture tail water into nitrate nitrogen. The system is divided into four independent areas in sequence, namely, a preliminary contact area, an intensive reaction area, a buffer area and a pH adjustment area. The bottoms of the first three areas are provided with aerated stones and air tubes, and then microbial attachment bases are accumulated on the aerated stones and air tubes. The direction of the water tubes in the microbial attachment bases is parallel to the direction of the water flow. The microbial attachment bases in the preliminary reaction area, the intensive reaction area and the buffer area are arranged in an outward-stretched trapezoid. No microbial attachment bases and aerated stones are placed in the pH adjustment area. The tail water treatment volume capacity of the system accounts for 6 / 10 to 7 / 10 of the total water treatment system. When the system is working, firstly, the cultured nitrifying bacteria are 9 cfu / ml is diluted 1000 times with seawater and sprinkled on the microbial attachment base. The initial addition amount of the diluent is 0.02% of the treated water volume per unit time, and then filled with aquaculture tail water. During this period, the water temperature is kept above 15°C and aeration is maintained for more than 5 days. After that, NaOH is used to adjust the pH in the pH adjustment area to 8.5≤pH≤10; The anaerobic denitrification conversion system is a device that converts nitrate nitrogen in aquaculture tail water into nitrogen gas. The device enables denitrifying bacteria to convert nitrate nitrogen into nitrogen gas under anaerobic conditions and discharge it into the air. The system requires that the microbial attachment base be accumulated in the system, and the direction of the water pipe in the microbial attachment base is parallel to the direction of water flow. The tail water treatment volume capacity of the system accounts for 2 / 10 to 3 / 10 of the total water treatment system volume; When the system is running, firstly, the cultured denitrifying bacteria 10 9 cfu / ml is diluted 1000 times with seawater and sprinkled on the microbial attachment base. The initial total amount of the diluent added is 0.2% of the treated water volume per unit time. Then fill it with the aquaculture tail water after the previous stage of treatment. During this period, the water temperature is kept above 15℃. Aeration is strictly prohibited and maintained for more than 3 days. The COD reduction system is a device for reducing COD in aquaculture tail water. When the system is constructed, the bottom aerated stones and air pipes are first arranged, and then the microbial attachment base is piled up. The tail water treatment volume capacity of the system accounts for 1 / 10 to 2 / 10 of the total water treatment system volume; When the system is running, the composite microorganisms (10 9 cfu / ml) was diluted 1000 times and sprinkled on the microbial attachment base. The initial addition amount of the dilution was 0.5% of the treated water volume per unit time, and then the aquaculture tail water after the previous stage of treatment was added.

2. A novel marine aquaculture tail water biological treatment process according to claim 1, characterized in that The microbial attachment base is a customized microbial attachment base, which is pressed from a renewable composite plastic material. Its shape and size are customized according to the shape requirements of each system. The main body of the microbial attachment base is in the shape of a honeycomb tube. The inner diameter of the tube can be adjusted according to the tail water treatment volume capacity of each system, between 1 and 5 cm. The amount of tail water treated per unit time is proportional to the inner diameter of the tube. The water pipe in the microbial attachment base is parallel to the direction of water flow.

3. A novel marine aquaculture tail water biological treatment process according to claim 1 or 2, characterized in that The microorganism attachment base is formed by stacking a number of unit modules.

4. A novel biological treatment process for marine aquaculture tail water according to claim 1, characterized in that The microbial attachment base is customized in an integrated manner according to the shape of the system.

5. A novel biological treatment process for marine aquaculture tail water according to claim 1, characterized in that The nitrifying bacteria used in the aerobic nitrification conversion system for inoculation and culture screening are based on nitrifying bacteria separated from the bottom mud of seawater ponds as the original strains, which are freeze-dried after fermentation and expansion culture. The separation method is conventional plate coating and streak culture method, and after separation, they are identified as corresponding strains by 16SrRNA.

6. A novel biological treatment process for marine aquaculture tail water according to claim 1, characterized in that The denitrifying bacteria used in the anaerobic denitrification conversion system are high-salt-tolerant denitrifying bacteria separated from the bottom mud of aquaculture ponds. The separation method is conventional plate coating and streak culture method. After separation, the bacteria are identified as corresponding species by 16S rRNA.

7. A novel biological treatment process for marine aquaculture tail water according to claim 1, characterized in that The composite microorganisms used in the COD reduction system are composed of high-salt-tolerant Bacillus subtilis and Enterococcus faecalis, and the biomass ratio of the two is 1:1.

Images