Method for rapid start-up of a marine biofilter

Abstract

The application discloses a kind of quick start method of seawater biological filter, comprising the following steps: 1) parameter adjustment;2) raw filler addition;3) aeration culture;4) start successfully.The present application uses mature biofilm as inoculant, evaluates the formation of nitrifying biofilm in the practice of recirculating aquaculture, selects K5 and flexible filler commonly used in biological filter, adjusts the ratio of raw and mature filler in biological filter to shorten the biofilm formation time, the present application uses raw biofilm filler and mature biofilm filler mixed culture, can quickly complete the start of seawater biological filter, and after successful start, the biofilm filler of the present application can be directly used for the start of next batch of seawater biological filter, without purchasing exogenous bacterial agent, saving cost.The present application studies to accelerate the biofilm formation process of biological filter using mature biofilm as inoculant, greatly shortens the establishment time of nitrification process.

Description

Technical Field

[0001] This invention relates to the field of aquaculture biological filter technology, specifically to a rapid start-up method for a seawater biological filter. Background Technology

[0002] Biofilm technology involves adding a biofilm carrier to allow nitrifying microorganisms to attach and grow. This not only effectively removes nitrogenous compounds, especially highly toxic ammonia and nitrite, improving shrimp survival and growth rates, but also provides the biofilm as an additional food source for shrimp, offering essential nutrients such as unsaturated fatty acids, amino acids, and vitamins. It has become a widely adopted method for denitrification in aquaculture water. Currently, existing biofilm methods include natural biofilm formation and inoculated biofilm formation. Natural biofilm formation requires a longer formation time, constant aeration after nitrogen source addition, and 20-40 days to establish nitrification under natural conditions (21-26℃). Inoculation with exogenous nitrifying bacteria or exogenous extracellular polymers can rapidly establish nitrification capacity, but exogenous agents are expensive, and the aquaculture water has a high load and large volume, requiring large quantities of exogenous agents, making it costly and uneconomical.

[0003] Patent publication number CN114772711B discloses a rapid biofilm formation method for a moving biological bed. The method includes the following steps: Step 1: Cleaning the filter media; Step 2: Adding ammonium chloride to the moving biological bed; Maintaining the ammonia nitrogen concentration in the water at 10-15 mg / L; pH at 7.0-8.0; and alkalinity at 50-150 mmol / L by adding ammonium chloride; Stopping the addition of ammonium chloride when the ammonia nitrogen concentration in the water decreases from 10 mg / L to 0-0.5 mg / L within 24 hours; Then, measuring the nitrite concentration in the water daily using a rapid nitrite detection kit; When the nitrite concentration decreases at a rate of 10-15 mg / L / day and the nitrite concentration in the water is below 0.5 mg / L, draining the water from the moving biological bed. At this point, the initial biofilm formation on the biological filter media in the moving biological bed is complete.

[0004] However, this patent uses a natural biofilm formation method. Ammonia-oxidizing bacteria use ammonia nitrogen from ammonium chloride as a nitrogen source to grow first. After the ammonia-oxidizing bacteria convert the ammonia nitrogen into nitrite, the nitrite-oxidizing bacteria then use the nitrite to grow. It is a process from 0 to 1, which takes a long time and involves complicated procedures. Summary of the Invention

[0005] The present invention aims to provide a rapid start-up method for a marine biofilter, which involves inoculating a mature biofilm carrier during biofilm formation as a source for releasing cells or biofilm fragments, thereby shortening the biofilm formation time and being economical.

[0006] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0007] A rapid start-up method for a marine biological filter includes the following steps:

[0008] 1) Parameter adjustment: Adjust the water temperature in the biological filter to 25-27℃ and the pH value of the water in the biological filter to 7.5-8.2;

[0009] 2) Addition of raw and cooked biofilm packing: The biofilm packing is added to the biological filter, wherein the biofilm packing includes cooked biofilm packing and raw biofilm packing, and the volume ratio of the cooked biofilm packing to the total biofilm packing is 5-20%;

[0010] 3) Aeration culture: Add ammonium chloride to the water until the NH4+ level in the water is reached. + The NH4+ concentration was 12-20 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - When the concentration of NH4+ in the water drops below 0.5 mg / L, ammonium chloride is added again to the water. + The -N concentration was 12-20 mg / L, and the aeration culture was repeated 3 times.

[0011] 4) Startup successful;

[0012] In step 3), the aeration culture includes the following three stages:

[0013] I. Microbial colonization period: Add ammonium chloride to the water body until the NH4+ level is reached. + The NH4+ concentration was 12-14 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - When the concentrations of -N all decrease to below 0.5 mg / L, the microbial culture period begins.

[0014] II. Microbial cultivation period: Add ammonium chloride to the water until the NH4+ level in the water is reached. + The NH4+ concentration was 14-16 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 -When the concentrations of -N drop below 0.5 mg / L, the biofilm enters the maturation stage.

[0015] III. Biofilm maturation stage: Ammonium chloride is added to the water body until the NH4+ level reaches the target concentration. + The NH4+ concentration was 16-20 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - The aeration culture was completed when all -N levels dropped below 0.5 mg / L.

[0016] Furthermore, in step 1), the filler is polypropylene K5 filler or polyurethane flexible filler;

[0017] Furthermore, in step 1), the mature biofilm packing material is a polypropylene K5 packing material or a polyurethane flexible packing material that has been inoculated with nitrifying bacteria and cultured to maturity.

[0018] Furthermore, the polypropylene K5 packing material occupies 13-17% of the water volume; the polyurethane flexible packing material occupies 27-33% of the water volume.

[0019] Furthermore, in step 3), during aeration and cultivation, the pH value of the water is measured every 24 hours. When the pH value is lower than 7.5, calcium hydroxide is added to adjust the pH value of the water to 7.5-8.2.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention uses mature biofilm as an inoculum to evaluate the formation of nitrifying biofilm in recirculating aquaculture practices. It selects K5, a commonly used biofilter, and flexible packing material, and shortens the biofilm formation time by adjusting the ratio of raw and mature packing material in the biofilter (5-20%), thus providing a method for quickly starting up a biofilter.

[0022] 2. In this invention, dissolved oxygen levels during the cultivation process must be above 8 mg / L because dissolved oxygen concentration significantly affects the ratio of aerobic / anaerobic microorganisms in the water, thus affecting the nitrification rate. Nitrification is significantly reduced when dissolved oxygen concentration is too high or too low. Excessive dissolved oxygen may lead to the loss of nitrifying microorganisms, while insufficient dissolved oxygen can cause competition between other aerobic bacteria and nitrifying bacteria, inhibiting nitrifying microorganisms and thus affecting nitrification. 8 mg / L of dissolved oxygen ensures normal growth of nitrifying bacteria. The concentration of dissolved oxygen increases sequentially in the three stages of aeration cultivation, mainly because each stage has a different purpose. The first stage is the microbial colonization period, where ammonium chloride is added primarily to provide nutrients for nitrifying microorganisms to colonize the biological packing material. The second stage is the microbial cultivation period, where a large number of nitrifying microorganisms have already attached to the packing material; a higher concentration of ammonium chloride is added to acclimate their nitrification capacity, gradually increasing it. The third stage is the biofilm maturation period, where a nitrifying biofilm forms on the packing material, possessing a high ammonia nitrogen treatment capacity; ammonium chloride, slightly higher than the treatment capacity, needs to be added to continuously consolidate and strengthen this capacity.

[0023] 3. This invention uses a mixed culture of live and cooked biofilm packing materials, which can quickly start up a seawater biofilter. After successful start-up, the biofilm packing material of this invention can be directly used to start up the next batch of seawater biofilters without the need to purchase exogenous bacterial agents, thus saving costs.

[0024] 4. This invention studies the use of mature biofilm as inoculum to accelerate the biofilm formation process in biofilters. After inoculation with mature biofilm, complete nitrification is rapidly achieved in the reactor. Higher ammonia oxidation rates were observed in the experimental group with a larger inoculum amount, but even with a 5% inoculum amount, uniform removal (approximately 92.66%) was gradually achieved. In the experimental group with a 20% mature biofilm packing material content, it took 18 hours for the ammonia to become undetectable, while the time required for natural biofilm formation was 108 hours, greatly shortening the nitrification process establishment time.

[0025] 5. In this invention, the polypropylene K5 packing material accounts for 13-17% of the water volume; the polyurethane flexible packing material accounts for 27-33% of the water volume; the specific surface area of ​​a single polyurethane flexible packing material is equivalent to 13.46 times that of the polypropylene K5 packing material. The theoretical nitrification rate of the polyurethane flexible packing material is 500~1200 NH3-N / m³.d, and the theoretical nitrification rate of the polypropylene K5 packing material is 600~1250 NH3-N / m³.d. Based on the calculation that the polyurethane flexible packing material is added at 15% of the water volume and the polypropylene K5 packing material is added at 30% of the water volume, the number of polyurethane flexible packing materials used per 10L of water is 78 pieces, and the number of polypropylene K5 packing materials is 630 pieces. At this point, the theoretical nitrification rates of the two types of packing materials are the same. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the rapid start-up method for the marine biological filter of the present invention.

[0027] Figure 2 NH4 in Examples 1-3 and Comparative Examples 1-2 of this invention + Schematic diagram of -N concentration change over time.

[0028] Figure 3 NH4 in Examples 4-6 of this invention + Schematic diagram of -N concentration changing over time.

[0029] Figure 4 NO2 in Examples 1-3 and Comparative Examples 1-2 of this invention - Schematic diagram of -N concentration change over time.

[0030] Figure 5 NO2 in Examples 4-6 of this invention - Schematic diagram of -N concentration changing over time.

[0031] Figure 6 This is a diagram showing the biofilm growth at different stages using polyethylene K5 filler in Example 1 of the present invention.

[0032] Figure 7 This is a diagram showing the biofilm growth at different stages of the polyurethane flexible filler in Example 4 of the present invention. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0034] Example 1

[0035] This embodiment provides a method such as Figure 1 The rapid start-up method for the marine biological filter shown includes the following steps:

[0036] 1) Parameter adjustment: Adjust the water temperature in the biological filter to 25-27℃ and the pH value of the water in the biological filter to 7.5-8.2;

[0037] 2) Addition of raw and cooked biofilm packing: The biofilm packing is added to the biological filter, wherein the biofilm packing includes cooked biofilm packing and raw biofilm packing, and the volume ratio of the cooked biofilm packing to the total biofilm packing is 5%;

[0038] 3) Aeration culture, including the following 3 stages:

[0039] I. Microbial colonization period: Add ammonium chloride to the water body until the NH4+ level is reached. + The NH4+ concentration was 12 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours.+ -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - When the concentrations of -N all decrease to below 0.5 mg / L, the microbial culture period begins.

[0040] II. Microbial cultivation period: Add ammonium chloride to the water until the NH4+ level in the water is reached. + The NH4+ concentration was 14 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - When the concentrations of -N drop below 0.5 mg / L, the biofilm enters the maturation stage.

[0041] III. Biofilm maturation stage: Ammonium chloride is added to the water body until the NH4+ level reaches the target concentration. + The N-N concentration was 16 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ in the water was measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - The aeration culture was completed when all -N levels dropped below 0.5 mg / L.

[0042] During aeration culture, the pH value of the water is measured every 24 hours. When the pH value is lower than 7.5, calcium hydroxide is added to adjust the pH value of the water to 7.5-8.2.

[0043] 4) Startup successful;

[0044] In this embodiment, the polypropylene K5 packing material was purchased from Shandong Banghao Environmental Protection Technology Co., Ltd., and the matured biofilm packing material was derived from the matured polypropylene K5 packing material that had been inoculated with nitrifying bacteria during the previous batch of aquaculture. The experiment was conducted in a 0.3×0.3×0.5m plastic tank with 10L of experimental water (salinity 30‰). There were 28 fresh biofilm packing materials and 539 matured biofilm packing materials. Ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen were measured using a fully automated water quality analyzer, and pH was measured using a pH meter (pH610, WIGGENS, Germany). Data were processed and expressed as mean and standard error (mean ± SE). Error bars represent standard error. Analysis of variance was used to determine differences, and P < 0.05 was considered significant.

[0045] Example 2

[0046] The difference between this embodiment and Embodiment 1 is that, in this embodiment, the mature biofilm packing material accounts for 10% of the total volume of the biofilm packing material; the polypropylene K5 packing material accounts for 30% of the water volume; and ammonium chloride is added to the water to the NH4 level during the microbial colonization period. + -N concentration was 14 mg / L; during the microbial culture period, ammonium chloride was added to the water until NH4+ was reached. + -N concentration was 16 mg / L; during the biofilm maturation period, ammonium chloride was added to the water to reduce NH4+. + -N concentration was 20 mg / L; 63 fresh biofilm fillers and 567 mature biofilm fillers were used, and the remaining steps were the same as in Example 1.

[0047] Example 3

[0048] Compared with Example 1, the difference in this embodiment is that, in this embodiment, the mature biofilm packing material accounts for 20% of the total volume of the biofilm packing material; the polypropylene K5 packing material accounts for 33% of the water volume; and ammonium chloride is added to the water to the NH4 level during the microbial colonization period. + -N concentration was 13 mg / L; during the microbial culture period, ammonium chloride was added to the water until NH4+ was reached. + -N concentration was 15 mg / L; during the biofilm maturation period, ammonium chloride was added to the water to reduce NH4+. + -N concentration was 18 mg / L; 139 raw biofilm fillers and 554 mature biofilm fillers were used, and the remaining steps were the same as in Example 1.

[0049] Example 4

[0050] The difference between this embodiment and Embodiment 1 is that, in this embodiment, the biofilm packing material used is polyurethane flexible packing material, and the matured biofilm packing material accounts for 5% of the total volume of the biofilm packing material; it was purchased from Tongxiang Xiaolaoban Special Plastics Sales Co., Ltd., and the matured biofilm packing material originated from the polyurethane flexible packing material that had been cultured and matured during the previous batch of aquaculture and inoculated with nitrifying bacteria.

[0051] The polyurethane flexible packing filler occupies 13% of the water volume; 4 mature biofilm packing fillers are added, and 64 raw biofilm packing fillers are added. The remaining steps are the same as in Example 1.

[0052] Example 5

[0053] The difference between this embodiment and embodiment 4 is that, in this embodiment, the biofilm packing material used is a polyurethane flexible packing material, and the volume ratio of the mature biofilm packing material to the total biofilm packing material is 10%.

[0054] The polyurethane flexible packing filler occupies 15% of the water volume; 8 mature biofilm packing fillers are added, and 70 raw biofilm packing fillers are added. The remaining steps are the same as in Example 1.

[0055] Example 6

[0056] The difference between this embodiment and embodiment 4 is that, in this embodiment, the biofilm packing material used is a polyurethane flexible packing material, and the volume ratio of the mature biofilm packing material to the total biofilm packing material is 20%.

[0057] The polyurethane flexible packing filler accounts for 17% of the water volume; 18 mature biofilm packing fillers and 71 raw biofilm packing fillers are added, and the remaining steps are the same as in Example 1.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that no cooked biofilm filler was added in this comparative example; all the fillers used were raw biofilm fillers. The remaining steps were the same as in Example 1.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 1 is that no live biofilm filler was added in this comparative example; instead, cooked biofilm filler was used entirely. The remaining steps are the same as in Example 1.

[0062] Comparative Example 3

[0063] The difference between this comparative example and Example 1 is that the volume ratio of the cooked biofilm packing material to the total biofilm packing material is 3% in this comparative example; the remaining steps are the same as in Example 1.

[0064] Comparative Example 4

[0065] The difference between this comparative example and Example 1 is that the volume ratio of the mature biofilm packing material to the total biofilm packing material is 30% in this comparative example; the remaining steps are the same as in Example 1.

[0066] Figure 2 NH4 in Examples 1-3 and Comparative Examples 1-2 of this invention + Schematic diagram of -N concentration change over time; Figure 3 NH4 in Examples 4-6 of this invention + Schematic diagram of -N concentration change over time; Figure 4 NO2 in Examples 1-3 and Comparative Examples 1-2 of this invention - Schematic diagram of -N concentration change over time; Figure 5 NO2 in Examples 4-6 of this invention - Schematic diagram of -N concentration changing over time; as shown in the figure. Figure 2 and Figure 3 It can be seen that after the initial addition of ammonium chloride, the NH4 in Examples 1, 2, and 3... +The time required for the -N concentration to decrease to approximately 2 mg / L was 42 h, 24 h, and 18 h, respectively, for NH4 in Examples 4, 5, and 6. + The time required for the -N concentration to drop to around 2 mg / L was 42 h, 42 h, and 24 h, respectively, all shorter than the time required for Comparative Example 1 (108 h). After the third addition of ammonium chloride, the ammonia nitrogen conversion rates within 24 h for Examples 1, 2, and 3 were 0.55 mg / (L·h), 0.61 mg / (L·h), and 0.6 mg / (L·h), respectively, with no significant difference among the three groups in Examples 1-3 (P > 0.05). The ammonia nitrogen conversion rates within 24 h for Examples 4, 5, and 6 were 0.42 mg / (L·h), 0.48 mg / (L·h), and 0.57 mg / (L·h), respectively, with significant differences among the three groups in Examples 4-6 (P < 0.05). The presumed reason is that the flexible packing has a complex internal structure, making it difficult to colonize in the early stages, resulting in a slower nitrification rate. However, the flexible packing has a rough surface that is not easily affected by water flow, so it exhibits superior nitrification capacity during the biofilm maturation period. Higher ammonia oxidation rates were observed in the experimental groups with higher inoculum sizes during the microbial colonization period. However, during the biofilm maturation period, even in the 5% mature flexible packing group, ammonia was gradually removed uniformly (approximately 92.66%). The addition of mature biofilms was beneficial to ammonia conversion.

[0067] like Figure 4 and Figure 5 It can be seen that the cumulative nitrite levels at 6 hours in Examples 1-3 were 0.36-0.83 mg / (L·h), showing a significant difference (P<0.05). After the first addition, Examples 1, 2, and 3 showed peak values ​​at 42 hours, 24 hours, and 18 hours, respectively. In Example 4, nitrite accumulated continuously and reached its peak at 122 hours. Examples 5 and 6 showed peak values ​​at 30 hours and 24 hours, respectively. After three additions, the peak values ​​for Examples 1, 2, and 3 were 32.96 mg / L, 24.17 mg / L, and 7.79 mg / L, respectively, while the peak values ​​for Examples 5 and 6 were 19.28 mg / L and 10.46 mg / L, respectively. Examples 1-3 showed significant differences, as did Examples 4-6 (P<0.05). This indicates that compared to the 5% and 10% mature packing materials in Examples 4 and 5, the 20% mature packing material in Example 6 had a higher nitrite conversion capacity and NO2 content. - The lowest N-N accumulation and the highest nitrite conversion rate indicate that inoculating with mature biofilm packing material possesses high nitrification capacity and has great potential for shortening the start-up time of nitrifying biofilm reactors.

[0068] After the first addition of ammonium chloride for 24 hours, there was a significant difference in the ammonia oxidation rate between Examples 2 and 4 (P < 0.05). After the third addition for 24 hours, there was no significant difference in the ammonia oxidation rate between Examples 2 and 4 (P > 0.05). After the third addition, the peak nitrite levels in Examples 4 and 2 were 24.17 mg / L and 19.28 mg / L, respectively, with no significant difference (P > 0.05). This is presumably because nitrite-oxidizing bacteria grow slowly, and the mature biofilm at this ratio cannot quickly initiate the nitrite oxidation process. During the microbial colonization period, the K5 packing material showed greater catalytic activity, exhibiting a higher ammonia oxidation rate than the flexible packing group. This is because the flexible packing material has a complex internal structure and a large surface area, allowing for greater microbial colonization, and its rough surface is less affected by water flow. Therefore, the flexible packing material exhibits superior nitrification capacity during the biofilm maturation period.

[0069] like Figure 6 The figure shows the biofilm growth at different stages using polyethylene K5 packing material in Example 1; as shown Figure 7 The figure shows the biofilm growth at different stages of the polyurethane flexible filler in Example 4.

[0070] Simultaneous microscopic images of two types of packing materials were selected during the acclimatization period of the biofilter. Figure 6 and Figure 7 It is evident that more microorganisms adhered to the K5 packing material in the early stage of domestication, while microorganisms on the K5 packing material were difficult to adhere to in the later stage of domestication due to the limitation of specific surface area. In contrast, the flexible packing material has a more complex structure and a larger specific surface area, which allows more microorganisms to colonize it.

[0071] Furthermore, by adding raw and mature biofilm carriers in appropriate volume ratios, as shown in Comparative Examples 3 and 4, it can be concluded that adding a portion of mature biofilm carriers to biofilm culture may be a potential alternative to shortening the biofilm culture time. The higher the proportion of mature biofilm carriers, the faster the nitrification capacity is acquired. If the proportion of mature carriers is too low, a longer acclimatization time is required, a larger total amount of reagents are needed, and the required reagent costs are higher, as in Comparative Example 3. If the proportion of mature carriers is too high, a large amount of reagents need to be added in the early stage of acclimatization to meet the growth of the existing microorganisms in the mature carriers, resulting in increased labor intensity and reagent costs, as in Comparative Example 4.

[0072] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A rapid start-up method for a seawater biological filter, characterized in that: Includes the following steps: 1) Parameter adjustment: Adjust the water temperature in the biological filter to 25-27℃ and the pH value of the water in the biological filter to 7.5-8.2; 2) Addition of raw and cooked biofilm packing: The biofilm packing is added to the biological filter, wherein the biofilm packing includes cooked biofilm packing and raw biofilm packing, and the volume ratio of the cooked biofilm packing to the total biofilm packing is 5-20%; The biofilm packing material is polypropylene K5 packing material or polyurethane flexible packing material; The mature biofilm packing material is polypropylene K5 packing material or polyurethane flexible packing material that has been inoculated with nitrifying bacteria and cultured to maturity. 3) Aeration culture: includes the following 3 stages: I. Microbial colonization period: Add ammonium chloride to the water body until the NH4+ level is reached. + The NH4+ concentration was 12-14 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - When the concentrations of -N all decrease to below 0.5 mg / L, the microbial culture period begins. II. Microbial cultivation period: Add ammonium chloride to the water until the NH4+ level in the water is reached. + The NH4+ concentration was 14-16 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - When the concentrations of -N drop below 0.5 mg / L, the biofilm enters the maturation stage. III. Biofilm maturation stage: Ammonium chloride is added to the water body until the NH4+ level reaches the target concentration. + The NH4+ concentration was 16-20 mg / L. Aeration was performed in the biological filter to control the dissolved oxygen level to be greater than 8 mg / L. NH4+ levels in the water were measured every 12 hours. + -N and NO2 - -N concentration, NH4+ in water body + -N and NO2 - The aeration culture was completed when all -N levels dropped below 0.5 mg / L. 4) Startup successful.

2. The rapid start-up method for the seawater biological filter according to claim 1, characterized in that: The polyurethane flexible filler occupies 13-17% of the water volume.

3. The rapid start-up method for the seawater biological filter according to claim 1, characterized in that: In step 3), during aeration and cultivation, the pH value of the water is measured every 24 hours. When the pH value is lower than 7.5, calcium hydroxide is added to adjust the pH value of the water to 7.5-8.2.

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