A method for achieving in-situ water treatment in a mariculture system

Abstract

The present application relates to a kind of methods for realizing in-situ water treatment in mariculture system, including in factory workshop breeding pond, mariculture is bred in environment, according to the breeding object to determine breeding density, construct seawater in-situ biological floc breeding and water treatment system, seed selection: the breeding object and nitrification type biological floc of seawater in-situ biological floc breeding and water treatment system are selected;Oxygenation: 24 hours are filled with oxygenation, supplement the dissolved oxygen in water body, simultaneously make biological floc in suspended state avoid bottom sinking;Floc management: daily FV-15 of nitrification type floc in water body is measured with Ingolf tube, TSS of water body is determined at fixed time, when the TSS of water body exceeds set TSS range, siphon collection is carried out, to ensure the concentration of nitrification type biological floc in water body, water is not replaced in breeding process, in-situ water treatment of breeding system is realized using biological floc, without carrying out carbon source supplement, beneficial effect is in keeping high survival rate, short growth cycle is while in-situ breeding tail water treatment is carried out.

Description

[0001] This invention relates to the field of aquaculture, and more particularly to a method for in-situ water treatment in a marine aquaculture system. Background Technology

[0002] Biofloc Aquaculture Systems (BAS) can treat aquaculture wastewater, achieving water conservation, emission reduction, and even zero-water-exchange standards. Simultaneously, the microbial environment enables disease control in aquaculture, representing a solution to resource and environmental issues. This model is gradually being promoted in the commercial farming of shrimp and tilapia and has become a key area of ​​aquaculture research. Current technologies using bioflocs for aquaculture wastewater treatment primarily involve off-site wastewater treatment and also suffer from the need to add organic carbon sources.

[0003] For example, CN107279022A describes a recirculating aquaculture system and method based on bioflocs and biofilms, which uses bioflocs for treating wastewater from ex-situ aquaculture, but this method is costly and complex.

[0004] For example, CN107624682A describes a method for farming redfin pufferfish, which uses a conventional farming model without treating the wastewater from the farming process.

[0005] For example, CN104304118A, a low-cost tilapia farming method that combines feed and biofloc technology, requires the addition of a carbon source.

[0006] For example, CN 14940542A describes a method for aquaculture using bioflocs, which requires the addition of an extra carbon source.

[0007] For example, CN110628644A describes a novel biofloc and its application and method for raising Litopenaeus vannamei shrimp, which reduces the amount of compound feed and added carbon sources required. Summary of the Invention

[0008] The purpose of this invention is to design a method for in-situ water treatment in a marine aquaculture system, thereby solving the above-mentioned technical problems.

[0009] The specific technical solution of this invention is as follows: A method for in-situ water treatment in a marine aquaculture system, comprising: a marine aquaculture environment in a factory-style aquaculture pond; determining the culture density based on the cultured organisms; and constructing a marine in-situ biofloc culture and water treatment system, characterized by the following steps:

[0010] a. Seedling selection: Select the aquaculture species for in-situ biofloc and water treatment systems, wherein the in-situ biofloc is a nitrifying biofloc;

[0011] b. Oxygenation: Oxygenation is provided 24 hours a day to replenish dissolved oxygen in the water and keep the bioflocs in suspension to prevent them from sinking to the bottom;

[0012] c. Floc Management: The FV-15 of nitrifying flocs in the water is measured daily using an Inhofe tube, and the TSS of the water is measured at fixed intervals. When the TSS of the water exceeds the set TSS range, siphon collection is performed to ensure the concentration of nitrifying bioflocs in the water. No water changes are performed during the aquaculture process.

[0013] As an improvement, feeding is also included: feed 1% of the body weight of the animal each day, and feed at fixed times and locations according to the condition of the animal. Feeding should be done slowly depending on the feeding situation, and the amount of uneaten feed should be observed after feeding.

[0014] As a further improvement, alkalinity supplementation is also included: baking soda is added at 25% of the daily feed amount and according to the alkalinity of the water. The baking soda is dissolved in the treated seawater and sprinkled throughout the pond.

[0015] As a further improvement, the cultured species include redfin pufferfish and hybrid pufferfish.

[0016] As a further improvement, the seawater temperature is 20±3℃, the specific gravity is 1.017, and the pH value is 7.5-8.5.

[0017] As a further improvement, the concentration of the nitrified bioflocs is 100-400 mg / L.

[0018] As a further improvement, step c. floc management also includes timely water replenishment if the water level drops due to evaporation and adjustments to the concentration of nitrifying bioflocs.

[0019] As a further improvement, the TSS range is set to 100–400 mg / L.

[0020] This invention discloses a method for in-situ water treatment in a marine aquaculture system. It enables in-situ water treatment of the aquaculture system using bioflocs without the need for carbon source supplementation. The beneficial effects are that it maintains a high survival rate and a short growth cycle while treating aquaculture wastewater in situ. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the oxygenation step in Embodiment 1 of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] Pool body 1, bottom wall 11, center part of bottom wall 111, inner side wall 12, first aeration pipe 2, plug 21, three-way valve 3, air pump 4, annular second aeration pipe 5, fifth aeration pipe 6, air outlet 7, third aeration pipe 8, fourth aeration pipe 9, oxygen stone 10. Detailed Implementation

[0024] The embodiments of the present invention will be described in detail below with reference to examples.

[0025] Example 1

[0026] The method for in-situ water treatment in the marine aquaculture system of this embodiment includes, within a factory-style aquaculture pond, in a marine aquaculture environment, determining the culture density based on the cultured organisms, constructing a marine in-situ biofloc culture and water treatment system, and further includes the following steps:

[0027] a. Seedling selection: Redfin pufferfish was selected as the culture species for in-situ biofloc culture and water treatment system in seawater. The bioflocs were nitrifying bioflocs.

[0028] b. Culture environment: Seawater and nitrifying bioflocs. The seawater temperature is 20±3℃, specific gravity is 1.017, equivalent salinity is 22‰, pH is 7.5-8.5, and the concentration of nitrifying bioflocs is 100-200 mg / L. The culture density is determined according to the cultured organism. It should be noted that the nitrifying bioflocs are cultivated through the following steps:

[0029] S1 was prepared as a biofloc culture system. Freshwater-cultured bioflocs were placed in fully aerated freshwater. It should be noted that the freshwater-cultured bioflocs were the freshwater bioflocs cultivated by the biofloc reactor described in the literature (Liu Wenchang, Luo Guozhi, Tan Hongxin, et al., Treatment effect of biofloc reactor on wastewater in pilot-scale recirculating aquaculture system; Transactions of the Chinese Society of Agricultural Engineering; 2016, 32(08)) by the Shanghai Aquaculture Engineering Research Center of Shanghai Ocean University.

[0030] S2 added Bacillus subtilis to the biofloc culture system to obtain a mixed culture system containing bioflocs and Bacillus subtilis. The mixed culture system was then acclimatized to the salinity of seawater aquaculture by adding seawater or concentrated brine to the system in stages, increasing the salinity by 2 specific gravities each time. Culture was continued for 3 days at each salinity stage, finally raising the salinity to 20‰. The system was cultured for 12 days under conditions of a water temperature of 20±3℃, a pH range of 7.5-8.5, and moderate aeration for 24 hours.

[0031] S3 was fed with low-carbon feed and alkalinity regulator in the mixed culture system and cultured for 40-60 days under the conditions of water temperature 20±3℃, pH value range of 7.5-8.5, and moderate aeration for 24 hours. The low-carbon feed used was a premix of vitamins and minerals for marine fish, purchased from Qingdao Saigelin Marine Biological Feed Co., Ltd.

[0032] Each kiloliter of mixed culture system contains 100-500g of bioflocs and 10-30g of Bacillus subtilis; the mass fraction of each component of the low-carbon feed is limited by the following parameters: protein not less than 50%, crude fat not less than 10%, crude fiber not more than 8.0%, and total phosphorus not less than 0.8%.

[0033] In each of the above steps, promptly separate any foam floating on the water surface and ensure that no solid matter is suspended on the container walls of the biofloc cultivation system or mixed cultivation system. Regularly test the water quality; observe the growth of the bioflocs and measure their concentration. If the concentration exceeds 200-300 mg / L based on total suspended solids (TSS), collect the bioflocs using sedimentation to prevent oxygen depletion at the bottom of the water body.

[0034] c. Feeding: Feed 1% of the fish's body weight daily. Depending on the fish's condition, feed at fixed times and locations. Feed slowly, depending on the feeding situation. Observe the amount of uneaten feed after feeding. It should be noted that the feed is a refined compound feed for marine fish, purchased from Qingdao Sailing Marine Biological Feed Co., Ltd. The main ingredients are: fish meal, shrimp meal, fish oil, grains, vitamins, minerals, etc. The main components of the product are: protein ≥50%, crude fat ≥10%, crude fiber ≤8.0%, crude ash ≤17.0%, lysine ≥2.4%, total phosphorus ≥0.8%, and moisture ≤12.0%.

[0035] d. Oxygenation: 24-hour oxygenation is performed to replenish dissolved oxygen in the water and to keep the bioflocs suspended, preventing them from sinking. It should be noted that step d., oxygenation, is implemented through the following methods:

[0036] like Figure 1 As shown, pool 1 is a 6m × 6m square cement pool. Eight first aeration pipes 2, each 1.75m long and 0.8-1.6cm in diameter, are fixed to the bottom wall 11 of pool 1, 0.5m away from the inner wall 12 of pool 1. Both ends of the first aeration pipes 2 are equipped with plugs 21, and the pipes are connected to the air pump outlet via three-way valves 3. A ring 5 with a radius of 0.4m is formed by the first aeration pipes 2 at the center 111 of the bottom 11 of pool 1. The two ends of the second aeration pipes 5 are fixedly connected via three-way valves 3. These three-way valves 3 are also connected to the air pump outlet 4, which is used to fill the pool 1 with air. The first and second aeration pipes are microporous nano-aeration pipes.

[0037] After the air pump is started and gas is introduced, the air encounters the inner wall and flows back and rotates, causing the water in the pool to roll and churn in one direction. When the biofloc rotates with the water to the center, the ring-shaped aeration pipe located at the center of the bottom of the pool inflates the water and causes it to roll. The gas moves upward, causing the water to flow to the surface and roll to both sides. The gas on the side closest to the inner wall of the pool encounters the force of the inner wall and then rotates and rolls, forming a backwash water flow.

[0038] e. Alkalinity supplementation: Add baking soda according to 25% of the daily feed amount and the alkalinity of the water. Dissolve the baking soda in the treated seawater and sprinkle it throughout the pond.

[0039] f. Floc Management: The FV-15 of nitrifying flocs in the water is measured daily using an Inhofe tube. The TSS of the water is measured at fixed intervals. When the TSS of the water exceeds the set TSS range, siphon collection is performed to ensure the concentration of nitrifying bioflocs in the water. No water changes are performed during the aquaculture process. If the water level drops due to evaporation and adjustment of the concentration of nitrifying bioflocs, water is replenished in time. It should be noted that the FV-15 is used to measure the settling volume of bioflocs in the aquaculture water after 15 minutes to observe the settling state and volume of bioflocs.

[0040] FV determination (sludge settling ratio)

[0041] Experimental preparation: 1L graduated cylinder, 100ml graduated cylinder

[0042] Experimental procedure: Take 1000ml of mixed water sample with a graduated cylinder → let stand for 5min → pour the supernatant back into the reactor, leaving about 100ml of lower sediment → transfer the lower sediment into a 100ml graduated cylinder and let stand for 5min → read the volume (ml) of the sediment flocs and record the data.

[0043] Determination of TSS (Total Suspended Solids Concentration)

[0044] Experimental preparation: 1L graduated cylinder, glass funnel, quantitative filter paper (needs constant weight), constant temperature drying oven, waste liquid container, electronic analytical balance;

[0045] Experimental Procedure: Take 1000ml of the mixed water sample using a graduated cylinder → Let it stand until the flocs completely settle (approximately 1 hour) → Pour the supernatant back into the reactor and filter the lower layer of precipitated flocs (constant weight of filter paper: Dry the filter paper at 103-105℃ for 1 hour → Cool for 30 minutes, weigh, accurate to 0.0002g, repeat the above operation until the difference between two weighings is less than 0.0005g. The constant weight of the filter paper is m0) → After filtration, dry at 103-105℃ (if crude protein and crude fat need to be measured, drying at 60-65℃ is required) → Weigh (m1) and record the data. TSS = m1 - m0 / V, where m1: weight of dried filter paper and flocs (g), m0: weight of filter paper (g), and V: volume of the mixed water sample (ml or L). The TSS of the water body is the concentration of nitrifying bioflocs. The TSS range is set to 100-200 mg / L, and the preferred TSS is set to 150 mg / L.

[0046] g. Water quality monitoring: Regularly measure TAN and NO2 in the water of the seawater in-situ biofloc aquaculture system.- Monitoring indicators such as -N to assess the impact of in-situ biofloc water treatment systems on TAN and NO2. - The influence of indicators such as -N. It should be noted that the determination of nitrite and ammonium salt content in water quality is based on the "Marine Survey Standard" (GBT2007). Nitrite determination uses the diazo-azo method, and ammonium salt determination uses the sodium hypobromite oxidation method. It should also be noted that TAN is total ammonia nitrogen, and NO2... - -N represents nitrite nitrogen in the water.

[0047] The test results showed that TAN (mg / L) was 0.3505 ± 0.0396, and NO2... - -N (mg / L) was 0.1153 ± 0.0826. The survival rate of the cultured redfin pufferfish was 75.3%, and the culture period (from fry to juveniles) was 120 days.

[0048] Example 2 (Hybrid Pufferfish)

[0049] Unlike Example 1, the selected pufferfish species were hybrid pufferfish, specifically red-finned pufferfish (♂) × yellow pufferfish (♀). The test results showed that TAN (mg / L) was 0.4188 ± 0.4420, and NO2... - -N (mg / L) was 0.2225 ± 0.1143.

[0050] The survival rate of the hybrid pufferfish was 76.7%, and the culture period (from fry to juvenile) was 120 days.

[0051] Example 3

[0052] Unlike Example 1, the concentration of the selected nitrifying bioflocs was 200-400 mg / L. The test results showed that TAN (mg / L) was 0.1476 ± 0.2237, and NO2... - -N (mg / L) was 0.0962 ± 0.1518.

[0053] The survival rate of the farmed redfin pufferfish was 75%, and the cultivation period (from fry to juveniles) was 120 days.

[0054] Compare with Example 1

[0055] Unlike Example 1, the water used in the selected aquaculture environment was from a factory-style recirculating aquaculture system. The test results showed that TAN (mg / L) was 0.6440 ± 0.1033, and NO2... - -N (mg / L) was 0.1927 ± 0.0883.

[0056] The survival rate of the farmed redfin pufferfish was 75.6%, and the cultivation period (from fry to juveniles) was 120 days.

[0057] Compare with Example 2

[0058] Unlike Example 1, during oxygenation, the bioflocs were not kept in suspension to prevent settling. The test results showed that TAN (mg / L) was 1.8416 ± 0.7451, and NO2... - -N (mg / L) was 3.2559 ± 3.1071.

[0059] The survival rate of the farmed redfin pufferfish was 43.3%, and the cultivation period (from fry to juveniles) was 120 days.

[0060] Compare with Example 3

[0061] Unlike Example 1, the floc management step was not performed. Test results showed TAN (mg / L) was 0.9095 ± 0.3916, NO2... - -N (mg / L) was 0.0968 ± 0.04987.

[0062] The survival rate of the farmed redfin pufferfish was 37.5%, and the cultivation period (from fry to juveniles) was 120 days.

[0063] Blank group

[0064] Seawater aquaculture was conducted in factory-scale workshops using a water exchange method, without the use of bioflocs. The seawater temperature was 20±3℃, specific gravity was 1.017, equivalent salinity was 22‰, and pH was 7.5-8.5. Continuous aeration was maintained for 24 hours. Feeding was administered at 1% of the cultured organisms' body weight daily, and half of the water was changed daily. Test results showed TAN (mg / L) was 0.0111±0.0033, and NO2... - -N (mg / L) was 1.0927 ± 0.0583.

[0065] The survival rate of the farmed redfin pufferfish was 75.8%, and the cultivation period (from fry to juveniles) was 120 days.

[0066] The test results show that Examples 1 and 3 are superior to Control Examples 1-4, which proves that water treatment steps such as the aquaculture environment (type and concentration of water and bioflocs) and floc management have an impact on the in-situ water treatment effect. The absence of any step such as the aquaculture environment or floc management will affect the in-situ water treatment effect. Example 1 is superior to Example 2, which proves that the concentration of nitrifying bioflocs in the aquaculture environment has an impact on the in-situ water treatment effect, with the optimal range being 100-200 mg / L.

[0067] The survival rate data of Examples 1 and 3 are better than those of Control Examples 2-3, which proves that water treatment steps such as the aquaculture environment (type and concentration of water and bioflocs) and floc management have an impact on the survival rate of cultured organisms. The absence of any step such as the aquaculture environment or floc management will affect the survival rate and culture cycle of cultured organisms. Although the survival rate and growth cycle data of the blank group are not much different from those of Examples 1 and 3, Examples 1 and 3 achieved in-situ culture without water changes.

[0068] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for achieving in-situ farming of red- fin pufferfish in a mariculture system, characterized by, The method comprises the following steps: a. Seed selection: selecting red-fin puffer fish as the breeding object; b. Breeding environment: breeding in a factory workshop tank; seawater and nitrifying biological floc, wherein the seawater has a water temperature of 20±3℃, a specific gravity of 1.017, a converted salinity of 22‰, and a pH value of 7.5-8.5; the nitrifying biological floc has a concentration of 100-200 mg / L; and the breeding density is determined according to the breeding object; The nitrifying biological floc is cultured through the following steps: S1: preparing a biological floc culture system, and placing the biological floc cultured in fresh water in fresh water with sufficient aeration; S2: adding Bacillus subtilis to the biological floc culture system to obtain a mixed culture system containing biological floc and Bacillus subtilis; and domesticating the mixed culture system to adapt to the salinity of seawater breeding, and adding seawater or concentrated salt water to the mixed culture system in batches to adjust the salinity, with the salinity being increased by 2 specific gravities each time; the mixed culture system is continuously cultured for 3 days at each salinity stage, and finally the salinity is increased to 20‰; the water temperature is maintained at 20±3℃, the pH value is in the range of 7.5-8.5, and the culture is carried out for 12 days under the condition of 24h moderate aeration; S3: adding low-carbon feed and alkalinity regulator to the mixed culture system, and continuously culturing for 40-60 days under the condition of maintaining the water temperature at 20±3℃, the pH value in the range of 7.5-8.5, and 24h moderate aeration; the low-carbon feed used is seawater fish special vitamin and mineral premix; wherein, per kiloliter of the mixed culture system contains 100-500g of biological floc and 10-30g of Bacillus subtilis; the mass fraction of each component of the low-carbon feed is limited according to the following parameters: protein not less than 50%, crude fat not less than 10%, crude fiber not more than 8.0%, and total phosphorus not less than 0.8%; In steps S1-S3, the foam floating on the surface of the water body is separated in time, and the container wall of the biological floc culture system or the mixed culture system is ensured to be free of solid material suspension; the water quality is regularly detected; the growth of the biological floc is observed, and the concentration of the biological floc is measured; if the concentration exceeds 200-300mg / L according to total suspended solids (TSS) measurement, the biological floc is collected by sedimentation to prevent oxygen deficiency at the bottom of the water body; c. Feeding: 1% of the body weight of the breeding object is fed every day, and the feeding is domesticated at a fixed time and a fixed position according to the condition of the breeding object; the feeding is slow according to the eating condition, and the residual feed is observed after eating; the feed is seawater fish refined compound feed, which is purchased from Qingdao Saigelin Marine Biological Feed Co., Ltd.; the raw materials for preparing the feed include fish meal, shrimp meal, fish oil, grains, vitamins, and minerals; d. Oxygenation: 24 hours of oxygenation, supplementing dissolved oxygen in the water body, while keeping the biological floc in suspension to avoid sinking to the bottom; the oxygenation step is implemented by the following method: the pool body (1) is a square cement pool with a size of 6m x 6m, 8 first aeration pipes (2) with a length of 1.75 meters and a pipe diameter of 0.8-1.6 centimeters are fixed on the bottom wall part (11) of the pool body (1), and are 0.5 meters away from the inner side wall (12) of the pool body (1); the two end parts of the first aeration pipe (2) are provided with plugs (21), and the pipe body is communicated with the air pump outlet through a three-way valve (3); the center (111) of the bottom (11) of the pool body (1) is provided with an annular (5) with a radius of 0.4 meters surrounded by the first aeration pipe (2), wherein the second aeration pipe (5) is fixedly connected through a three-way valve (3) at the two ends; at the same time, the three-way valve (3) is connected with the air outlet of the air pump (4), and the air pump (4) is used to fill air into the pool body (1); the first aeration pipe and the second aeration pipe are microporous nanometer aeration pipes; after starting the air pump to fill air, the air meets the inner wall and rotates back, causing the water in the pool to roll and stir in one direction; when the biological floc rotates to the center position with the water body, the annular aeration pipe located at the center position of the pool body bottom fills air to drive the water body to roll, the gas moves upward to cause the water flow to the water surface, and rolls to the two sides, the gas near the inner wall of the pool body encounters the action force of the inner wall and rotates to form a backflow; e. Alkalinity supplement: according to 25% of the daily feeding amount and the alkalinity in the water body, baking soda is supplemented, and the baking soda is dissolved in the treated seawater and sprayed throughout the pool; f. Floc management: FV-15 of nitrification type floc in the water body is measured every day with an Ingloff tube, TSS of the water body is measured at a fixed time, when the TSS of the water body exceeds the set TSS range, siphon collection is performed to ensure the concentration of nitrification type biological floc in the water body, and no water is changed during the breeding process; if the water level is lowered due to evaporation and adjustment of the concentration of nitrification type biological floc, water is supplemented in time, FV-15 is measured after the biological floc in the breeding water body is settled for 15 minutes, and is used to observe the settlement state and volume of the biological floc; g. Water quality monitoring: TAN and NO2--N of the water body in the seawater in-situ biological floc breeding system are measured at a fixed time.

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