Salt-tolerant heterotrophic nitrification-aerobic denitrification bacteria and high-phosphorus and high-nitrogen seawater treatment system

Abstract

The invention discloses a salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium and a high-phosphorus and high-nitrogen seawater treatment system. The system comprises a micro-nano aeration unit, a microbial denitrification unit and a denitrification and dephosphorization unit which are connected in sequence, the micro-nano aeration unit is used for providing an aerobic environment; the salt-resistant heterotrophic nitrification-aerobic denitrification bacteria are arranged in the microbial denitrification unit; the nitrogen and phosphorus removal unit comprises at least one group of seaweed culture ponds. According to the treatment system provided by the invention, through the coupling effect of the micro-nano aeration unit, the microbial denitrification unit and the denitrification and dephosphorization unit, the improvement of dissolved oxygen in a water body, the simplification of a microbial denitrification process and the improvement of the dephosphorization effect of the mariculture tail water are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium and a high-phosphorus and high-nitrogen seawater treatment system. Background Art

[0002] Aquaculture tail water has characteristics such as high nitrogen, high phosphorus, and high chemical oxygen demand, and its treatment requirements and standards are particularly stringent. At present, due to advantages such as high efficiency, economy, and low secondary pollution, biological treatment methods have gradually become the mainstream of current aquaculture tail water treatment means. The biological treatment method of tail water mainly creates favorable conditions such as culture medium, attachment base, and oxygen, and uses microorganisms to absorb and decompose pollutants in the water body. In early research, nitrifying bacteria and denitrifying bacteria were mostly used to treat aquaculture tail water in sequence. However, the diverse bacterial communities make this process relatively complex. With the development of modern biology and the continuous progress of biotechnology, many new microbial functions have been discovered, such as heterotrophic nitrification and aerobic denitrification. Compared with autotrophic microorganisms, heterotrophic nitrifying bacteria have a faster growth rate and stronger environmental adaptability; the discovery of aerobic denitrifying bacteria also makes it possible for the denitrification process not to strictly control anaerobic conditions, and synchronous nitrification and denitrification become possible.

[0003] However, the treatment efficiency of microbial treatment for highly saline nitrogen-containing wastewater generated from industrial cooling seawater in coastal cities, seafood aquaculture, etc. is low. The main reason is that high salinity will inhibit the growth and metabolic functions of microorganisms. On the other hand, seawater aquaculture tail water also has the characteristics of high phosphorus and high chemical oxygen demand. Relying solely on microorganisms to treat aquaculture tail water cannot achieve good results in the short term. Therefore, constructing diverse and effective tail water treatment systems is extremely important for realizing the purification of seawater aquaculture tail water.

[0004] Chinese invention patent CN202310339290.1 discloses the application of a solid-phase carbon source and autotrophic denitrification combined process in the treatment of seawater aquaculture tail water. This invention takes heterotrophic denitrification biological treatment with a solid-phase carbon source as a carrier and autotrophic denitrification biological treatment with a sulfur-iron alloy filter material as a carrier to remove nitrogen, phosphorus, and organic matter in seawater aquaculture tail water as the core, and then uses electrolytic flotation technology to treat seawater aquaculture tail water. However, it has defects such as complex processes, high operating costs, and unclear effects. Summary of the Invention

[0005] To solve the above problems, the present invention provides a treatment system and its application for seawater aquaculture tail water. This system uses heterotrophic nitrification-aerobic denitrification bacteria to carry out nitrogen removal treatment and reduction of chemical oxygen demand on the water body, and combines with a seaweed cultivation pond to further absorb and reduce residual nitrate nitrogen, ammonia nitrogen, and chemical oxygen demand, so as to achieve efficient treatment of seawater aquaculture tail water.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, the present invention provides a salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium Halomonas sp. NH3, which is classified and named as Halomonas hydrothermalis and was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on October 30, 2023. The deposit address is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, and the deposit number is CGMCC No. 28812.

[0008] On the other hand, the present invention provides an immobilized microbial pellet, and the above-mentioned salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium Halomonas sp. NH3 is immobilized on the immobilized microbial pellet.

[0009] As a preferred embodiment, the preparation method of the immobilized microbial pellet includes the following steps:

[0010] Disperse the embedding agent and the additive in the solvent and completely dissolve them; then mix with the bacterial suspension containing the above-mentioned heterotrophic nitrification-aerobic denitrification bacterium Halomonas sp. NH3; finally, add a cross-linking agent and obtain the immobilized microbial pellet through a gelation reaction;

[0011] Preferably, the embedding agent is a composition of polyethylene glycol and sodium alginate; the solvent is water; the concentration of polyethylene glycol in the solvent is preferably 5% - 9% (W / V, g / mL); the concentration of sodium alginate in the solvent is preferably 2% - 4% (W / V, g / mL);

[0012] Preferably, the additive is activated carbon; the concentration of activated carbon in the solvent is preferably 0.5% - 1.5% (W / V, g / mL);

[0013] Preferably, the mass ratio of polyethylene glycol, sodium alginate and activated carbon is 7:3:1.5;

[0014] Preferably, the cross-linking agent is a saturated boric acid solution containing calcium chloride; the concentration of calcium chloride is 2 - 5% (W / V, g / mL);

[0015] Preferably, the volume ratio of the cross-linking agent to the solvent is 0.5 - 2:1;

[0016] Preferably, the temperature of the gelation reaction is 2 - 4°C, and the time of the gelation reaction is 20 - 24 h;

[0017] In some specific embodiments, the dispersion is carried out under heating conditions, the heating temperature is 100 - 130°C, preferably 121°C; it needs to be cooled to below 40°C before mixing with the bacterial suspension.

[0018] On the other hand, the present invention provides a high-phosphorus and high-nitrogen seawater treatment system, which includes a micro-nano aeration unit, a microbial denitrification unit, and a denitrification and phosphorus removal unit connected in sequence; the micro-nano aeration unit is used to provide an aerobic environment; the microbial denitrification unit contains the above-mentioned salt-tolerant heterotrophic nitrification-aerobic denitrification bacteria; the denitrification and phosphorus removal unit includes at least one group of seaweed cultivation ponds.

[0019] As a preferred embodiment, the micro-nano aeration unit includes a motor, an air suction device, a micro-nano bubble diffusion device, a countercurrent mixer, and a gas-liquid vortex device; the air suction device is used to transport air into the water body; the micro-nano bubble diffusion device, the countercurrent mixer, and the gas-liquid vortex device are used to mix the water body; in the technical solution of the present invention, the micro-nano aeration unit is arranged in an aeration tank to increase the oxygen content of the seawater aquaculture tail water, so as to provide a favorable environment for the bacteria in the subsequent microbial denitrification unit; among them, the countercurrent mixer and the gas-liquid vortex device can promote the full contact of oxygen in the air with the water body, and the micro-nano bubble diffusion device generates micro-nano bubbles in the water body to increase the dissolved oxygen content in the water.

[0020] As a preferred embodiment, a plurality of immobilized microbial pellets are arranged in the microbial denitrification unit, and the above-mentioned salt-tolerant heterotrophic nitrification-aerobic denitrification bacteria are fixed on the immobilized microbial pellets;

[0021] As a preferred embodiment, the preparation method of the immobilized microbial pellets includes the following steps:

[0022] Disperse the embedding agent and the additive in the solvent and dissolve them completely; then mix them with the bacterial suspension containing the above-mentioned heterotrophic nitrification-aerobic denitrification bacteria Halomonas sp. NH3; finally, add a cross-linking agent and obtain the immobilized microbial pellets through a gelation reaction;

[0023] Preferably, the embedding agent is a composition of polyethylene glycol and sodium alginate; the solvent is water; the concentration of polyethylene glycol in the solvent is preferably 5% - 9% (W / V, g / mL); the concentration of sodium alginate in the solvent is preferably 2% - 4% (W / V, g / mL);

[0024] Preferably, the additive is activated carbon; the concentration of activated carbon in the solvent is preferably 0.5% - 1.5% (W / V, g / mL);

[0025] Preferably, the mass ratio of polyethylene glycol, sodium alginate, and activated carbon is 7:3:1.5;

[0026] Preferably, the cross-linking agent is a saturated boric acid solution containing calcium chloride; the concentration of calcium chloride is 2% - 5% (W / V, g / mL);

[0027] Preferably, the volume ratio of the crosslinking agent to the solvent is 0.5-2:1;

[0028] Preferably, the temperature of the gelation reaction is 2-4 °C, and the time of the gelation reaction is 20-24 h;

[0029] In some specific embodiments, the dispersion is carried out under heating conditions, and the heating temperature is 100-130 °C, preferably 121 °C; it needs to be cooled to below 40 °C before mixing with the bacterial suspension.

[0030] As a preferred embodiment, the seaweeds cultured in the seaweed culture pond are Ulva lactuca and / or Sargassum horneri;

[0031] Preferably, the seaweeds are Ulva lactuca and Sargassum horneri cultured in a mass ratio of 2-4:1;

[0032] Preferably, the culture density of the seaweeds is 8-10 g / L.

[0033] On the other hand, the present invention provides the application of the above treatment system in treating seawater with high phosphorus and high nitrogen.

[0034] Specifically, the seawater with high phosphorus and high nitrogen can include seawater aquaculture tail water, seawater industrial wastewater, etc.

[0035] Preferably, the application includes the following steps:

[0036] After the seawater with high phosphorus and high nitrogen is preliminarily settled, it is introduced into the micro-nano aeration unit for aeration treatment; then it is introduced into the microbial denitrification unit for denitrification; finally, it is introduced into the denitrification and phosphorus removal unit for denitrification and phosphorus removal.

[0037] The above technical solutions have the following advantages or beneficial effects:

[0038] The treatment system for the tail water of seawater aquaculture provided by the present invention includes a micro-nano aeration unit, a microbial denitrification unit, and a denitrification and phosphorus removal unit connected in sequence; the micro-nano aeration unit is used to provide an aerobic environment; there are salt-tolerant heterotrophic nitrification-aerobic denitrification bacteria in the microbial denitrification unit; the denitrification and phosphorus removal unit includes at least one group of seaweed cultivation ponds. The system aerates the water body through the micro-nano aeration unit to increase the dissolved oxygen in the water body and inhibit the release of nitrogen and phosphorus elements in the sediment, providing favorable conditions for the growth of subsequent heterotrophic nitrification-aerobic denitrification bacteria; subsequently, the heterotrophic nitrification-aerobic denitrification bacteria that can adapt to the high-salinity seawater aquaculture tail water are used to efficiently denitrify the water body and reduce the chemical oxygen demand; finally, in combination with the seaweed cultivation ponds, the residual nitrate nitrogen, ammonia nitrogen, and chemical oxygen demand in the water body are further absorbed and reduced, thereby realizing the efficient treatment of the seawater aquaculture tail water. The treatment system provided by the present invention realizes the improvement of the dissolved oxygen in the water body, the simplification of the microbial denitrification process, and the improvement of the phosphorus removal effect of the seawater aquaculture tail water through the coupling effect of the micro-nano aeration unit, the microbial denitrification unit, and the denitrification and phosphorus removal unit.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] (1) The strain used in the present invention is a salt-tolerant denitrifying strain, which can be domesticated from seawater aquaculture sludge, and can simultaneously realize the nitrification and denitrification processes under aerobic conditions, quickly convert nitrate nitrogen and ammonium nitrogen into nitrogen gas, and achieve efficient nitrogen removal; this strain has a strong ability to utilize sodium citrate, and after an adaptation period of one day in a culture solution with sodium citrate as the sole carbon source, it only takes 12 h to reach an extremely high bacterial density, fully consuming the nitrogen source in the culture solution, and the ammonia nitrogen removal rate is as high as 99%;

[0041] (2) In the present invention, a strain embedding material is prepared by mixing polyethylene glycol, sodium alginate, and activated carbon, which provides a stable growth environment for the strain, has a certain buffering property under drastic external changes, and can improve the denitrification performance of the strain in a complex environment; among them, activated carbon can indirectly promote the removal of nitrate by promoting the gene expression of denitrification functional genes and related genes participating in denitrification electron transfer;

[0042] (3) The present invention realizes the efficient and rapid denitrification and phosphorus removal of seawater aquaculture tail water through the comprehensive mode of micro-nano aeration for oxygenation - microbial denitrification - macroalgae phosphorus removal, reduces the floor area of equipment, reduces the operating cost, realizes the reduction of total nitrogen, nitrate nitrogen, and ammonium nitrogen at one step, and simplifies the process flow. Description of the Drawings

[0043] Figure 1 is the test result graph of the denitrification effect of the strain screened in Example 1 of the present invention on NH4 + -N.

[0044] Figure 2 It is the test result graph of the denitrification effect of the strain screened in Example 1 of the present invention on NO3 - -N.

[0045] Figure 3 It is the physical graph of the immobilized microbial pellets prepared in Examples 2-15 of the present invention.

[0046] Figure 4 It is the test result graph of the continuous denitrification performance of the immobilized microbial pellets prepared in Examples 2-15 of the present invention on NH4 + -N.

[0047] Figure 5 It is the structure graph of the high-phosphorus and high-nitrogen seawater treatment system in Example 3 of the present invention.

[0048] Figure 6 It is the test result graph of the removal effect of the high-phosphorus and high-nitrogen seawater treatment system in Example 3 of the present invention on NH4 + -N in the water body.

[0049] Figure 7 It is the test result graph of the removal effect of the high-phosphorus and high-nitrogen seawater treatment system in Example 3 of the present invention on NO3 - -N in the water body.

[0050] Figure 8 It is the test result graph of the removal effect of the high-phosphorus and high-nitrogen seawater treatment system in Example 3 of the present invention on PO4 - -P in the water body. Specific implementation manners

[0051] The following embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Therefore, the detailed descriptions in the embodiments of the present invention provided below are not intended to limit the scope of the claimed invention, but merely represent the selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0052] In the present invention, unless otherwise specified, all devices and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in this field.

[0053] Example 1:

[0054] In this example, a salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium Halomonas sp. NH3 is provided, and its screening and identification processes are as follows:

[0055] 10 mL of sludge samples collected from the secondary sedimentation tank of Zhujiajian Water Co., Ltd. were inoculated into a 250 mL conical flask containing 90 mL of sterilized HNM1 medium, and cultured in a shaker at 30 °C and 120 rpm for 3 days; inoculated into fresh HNM1 medium at the same inoculation amount and cultured in the shaker under the same conditions for another 3 days, and the enrichment process was repeated 3 times; the enriched bacterial solution was diluted 10 5 times, spread on HNM1 plates, placed in an electrothermal constant temperature incubator and cultured at 28 °C for 5 days; single colonies with different morphologies were selected and further purified to finally obtain a salt-tolerant strain. Combining the observation of colony morphological characteristics and the results of 16S rRNA sequencing, the biological classification of this strain was determined to be Halomonas sp., and it was named Halomonas sp. NH3.

[0056] HNM1 medium, including (g / L): (NH4)2SO4 2.0 g, MnSO4·4H2O 0.01 g, NaH2PO4 0.25 g, MgSO4·7H2O 0.03 g, CaCO3 0.5 g, K2HPO4 0.75 g, artificial seawater 1 L (containing 26.726 g NaCl, 2.26 g MgCl2, 3.248 g MgSO4, 1.153 g CaCl2, 0.198 g NaHCO3, 0.721 g KCl, 0.058 g NaBr, 0.058 g H3BO4, 0.0024 g Na2SiO3, 0.0015 g Na2Si4O9, 0.002 g H3PO4, 0.013 g Al2Cl6, 0.002 g NH3, 0.0013 g LiNO3), 21.74 g CH3COONa, pH 8.2 ± 0.2.

[0057] In this example, a denitrification effect experiment was carried out on the salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium Halomonas sp. NH3 screened, as follows:

[0058] The screened strain was inoculated into 100 mL of HNM2 medium at an inoculation amount of 10% (vol / vol), and cultured at 30 °C and 120 rpm for 72 h. A certain amount of nitrogen-containing inorganic compounds (including NH4Cl and KNO3) were added to the medium to make the initial NH4 + -N and NO3 - -N concentrations in the medium reach 100.04 ± 2.54 mg / L and 13.82 ± 0.12 mg / L respectively. Samples were collected every 12 h to measure the NH4 + -N and NO3 - - concentrations, and the test results are shown in Figure 1-2 .

[0059] Culture medium HNM2, including (g / L): (NH4)2SO4 0.4714 g, MnCl2·4H2O 0.01 g, NaH2PO4 0.25 g, MgSO4·7H2O 0.03 g, K2HPO4 0.75 g, Na3C6H5O7·2H2O 6.125 g, 1 L of artificial seawater (containing 26.726 g of NaCl, 2.26 g of MgCl2, 3.248 g of MgSO4, 1.153 g of CaCl2, 0.198 g of NaHCO3, 0.721 g of KCl, 0.058 g of NaBr, 0.058 g of H3BO4, 0.0024 g of Na2SiO3, 0.0015 g of Na2Si4O9, 0.002 g of H3PO4, 0.013 g of Al2Cl6, 0.002 g of NH3, 0.0013 g of LiNO3), pH 7.00 ± 0.05.

[0060] It can be seen from Figure 1 that after culturing for 72 h, the concentration of NH4 + -N in the culture solution is 5.39 ± 0.36 mg / L, and the removal rate of NH4 + -N by the screened strain can reach 94.6%.

[0061] It can be seen from Figure 2 that after culturing for 72 h, the concentration of NO3 - -N in the culture solution is 6.57 ± 0.68 mg / L, and the removal rate of NO3 - -N by the screened strain can reach 52.5%.

[0062] Example 2:

[0063] This example provides an immobilized microbial pellet, and the specific preparation process is as follows:

[0064] Step 1: Inoculate the strain Halomonas sp. NH3 obtained in Example 1 into the HNM1 liquid medium, and enrich and culture it at 30 °C and 120 rpm for 72 h; then centrifuge the culture solution at 6000 rpm / min for 10 min at 4 °C, discard the supernatant; wash it 2 - 3 times with sterile normal saline, and finally add 100 mL of sterile normal saline to obtain a bacterial suspension;

[0065] Step 2: Weigh 50 g of boric acid and add it to 500 mL of deionized water, stir it at 60 °C in a water bath for 5 min, take the supernatant after cooling to room temperature to prepare a saturated boric acid solution; add 25 g of CaCl2 to the saturated boric acid solution to obtain a cross-linking agent for later use;

[0066] Step 3: Add polyethylene glycol (PEG), sodium alginate (SA) and activated carbon (AC) into 100 mL of deionized water according to the settings in Table 1, sterilize at 121° C. for 20 min, and fully dissolve and mix;

[0067] Step 4: After the mixed solution has cooled, pour in the bacterial suspension and stir evenly; take 200 mL of the cross-linking agent in a beaker and place it on a magnetic stirrer, set a suitable speed, use a 10 mL syringe to draw the above mixed solution and titrate it at about 20 cm above the beaker, and control the titration speed to less than 3 drops per second. After cross-linking in a 4°C refrigerator for 24 hours, rinse with deionized water to finally obtain immobilized microbial pellets.

[0068] Table 1

[0069]

[0070]

[0071] This example prepared the immobilized microorganism pellets by the above ratios. Then, the best ratio of the immobilized microorganism pellets (Example 2-15) was confirmed to be PEG:SA:AC=7%:3%:1.5% (W / V) (Example 2-15) by comparing the spherical shape, permeability and elasticity. The actual picture of the prepared immobilized microorganism pellets is shown in Figure 3 .

[0072] This example further uses a nitrogen-containing solution to treat the optimal ratio of immobilized microbial pellets to NH4 + -N and NO3 - -N continuous denitrification performance was tested, the specific process is: prepare 100mL containing 100mg / LNH4 + -N aqueous solution; the immobilized microbial pellets prepared in Example 2-15 were placed in the above aqueous solution (the concentration of the bacteria contained in the immobilized microbial pellets in the aqueous solution was consistent with the test in Example 1); the solution containing the same concentration of NH4 was replaced every 24 hours. + -N aqueous solution, continuously measured for 7 days; by detecting NH4 + -N changes to observe its continued performance. Figure 4 It can be seen that the denitrification rate of the immobilized microbial pellets prepared in Examples 2-15 did not change significantly after 7 consecutive tests, and the pellets did not decompose, indicating that the immobilized pellet ratio in this experiment has good stability and can be reused many times.

[0073] Example 3

[0074] This embodiment provides a high-phosphorus and high-nitrogen seawater treatment system. Figure 5As shown, the system includes a micro-nano aeration unit, a microbial denitrification unit, and a denitrification and phosphorus removal unit that are connected in sequence.

[0075] In the high-phosphorus and high-nitrogen seawater treatment system provided in this embodiment:

[0076] The micro-nano aeration unit includes a motor, an air suction device, a micro-nano bubble diffusion device, a countercurrent mixer, and a gas-liquid vortex device; the air suction device is used to transport air into the water body; the micro-nano bubble diffusion device, the countercurrent mixer, and the gas-liquid vortex device are used to mix the water body; in the specific application process of the high-phosphorus and high-nitrogen seawater treatment system provided in this embodiment, the seawater to be treated first undergoes sedimentation in the primary sedimentation tank and then is introduced into the micro-nano aeration unit. The micro-nano aeration unit is arranged in the aeration tank, and the aeration duration is 8 hours per day, continuously treating for 10 days. It increases the oxygen content of the seawater aquaculture tail water to provide an aerobic and favorable environment for the bacteria in the subsequent microbial denitrification unit; among them, the countercurrent mixer and the gas-liquid vortex device can promote the full contact of oxygen in the air with the water body, and the micro-nano bubble diffusion device generates micro-nano bubbles in the water body, and the average diameter of the generated bubbles is 80 nm, so as to increase the dissolved oxygen content in the water. In the micro-nano aeration unit of this embodiment, after 10 days of continuous treatment, the iodometric method (GB 7489-87) was used to measure the dissolved oxygen concentration of the seawater aquaculture tail water before and after micro-nano aeration, and it was found that the average dissolved oxygen in the aeration tank increased by 4.0 mg / L;

[0077] Multiple immobilized microbial pellets prepared in Examples 2-15 are arranged in the microbial denitrification unit;

[0078] The denitrification and phosphorus removal unit includes a group of seaweed culture ponds, and the types and scales of the cultured seaweeds in the seaweed culture ponds are shown in Table 2.

[0079] The high-phosphorus and high-nitrogen seawater treatment system in this embodiment uses the aquaculture tail water of Zhoushan Aquaculture for experiments. The experimental period is set to 7 days. After the experiment, NH4 + -N, NO3 - -N, and PO4 - -P are detected. This experiment is carried out in a light incubator, the temperature is set to 25 °C, and a cycle of 16 hours of light - 8 hours of dark environment is maintained. At the beginning of the experiment, the concentrations of NH4 + -N, NO3 - -N, and PO4 - -P are 1.32 mg / L, 1.83 μmol / L, and 5.54 μmol / L respectively. After 7 days, the change trends of NH4 + -N, NO3 - -N, and PO4 - -P in the aquaculture water bodies of each experimental group are detected in turn, and the test results are shown in Figures 6 to 8 .

[0080] Table 2

[0081]

[0082]

[0083] Figure 6 Among them, the left figure is the test result under the single-culture mode. Among them, 0 g / L represents that there is no cultivated seaweed in the water, and it is the test result after 7 days under the same experimental conditions. The right figure is the test result under the polyculture mode. From Figure 6 it can be seen that both the single-culture and polyculture of Ulva lactuca and Sargassum horneri can effectively remove NH4 + -N in the water body. Among them, under the single-culture mode, the removal rate of NH4 + -N by 10 g / L of single-cultured Ulva lactuca in the water body is the highest, reaching 62.1%. While under the polyculture mode, when Ulva lactuca and Sargassum horneri are polycultured at a ratio of 8:2, the removal rate of NH4 + -N is the highest, reaching 45.5%.

[0084] Figure 7 Among them, the left figure is the test result under the single-culture mode. Among them, 0 g / L represents that there is no cultivated seaweed in the water, and it is the test result after 7 days under the same experimental conditions. The right figure is the test result under the polyculture mode. From Figure 7 it can be seen that under the single-culture mode, the removal effect of Ulva lactuca on NO3 - -N is better than that of Sargassum horneri. And when the cultivation density is 5 g / L and 10 g / L, the removal effect of Ulva lactuca on NO3 - -N is better, and the removal rates are 92.3% and 89.6% respectively. When Ulva lactuca and Sargassum horneri are polycultured, compared with the single-culture mode, the removal rate of NO3 - -N is significantly increased. Among them, when Ulva lactuca and Sargassum horneri are polycultured at a ratio of 8:2, the removal rate of NO3 - -N is as high as 97.3%.

[0085] Figure 8 Among them, the left figure is the test result under the single-culture mode. Among them, 0 g / L represents that there is no cultivated seaweed in the water, and it is the test result after 7 days under the same experimental conditions. The right figure is the test result under the polyculture mode. From Figure 8 it can be seen that whether it is single-culture or polyculture of Ulva lactuca and Sargassum horneri, there is no significant difference in the removal effect on PO4 - -P in the water body. Among them, under the single-culture mode, 10 g / L of Sargassum horneri has the best removal effect on PO4 - -P in the water body, and the removal rate reaches 79.2%. When polycultured, when the feeding ratio of Ulva lactuca and Sargassum horneri is 8:2, the removal effect on PO4 - -P is the best, and the removal rate is 73.3%.

[0086] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium, classified and named as Halomonas hydrothermalis, was deposited in the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on October 30, 2023, with the deposit number of CGMCC No. 28812.

2. An immobilized microbial pellet, characterized in that, The immobilized microbial pellets are immobilized with the salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium Halomonas hydrothermalis described in claim 1.

3. The immobilized microbial pellets according to claim 2, characterized in that, The preparation method of the immobilized microbial pellets comprises the following steps: Disperse the embedding agent and the additive in the solvent and completely dissolve them; then mix with the bacterial suspension containing the heterotrophic nitrification-aerobic denitrification bacterium Halomonas hydrothermalis; finally, add the crosslinking agent and obtain the immobilized microbial pellets through a gelation reaction.

4. The immobilized microorganism pellets according to claim 3, characterized in that, The embedding agent is a composition of polyethylene glycol and sodium alginate; the solvent is water; the concentration of polyethylene glycol in the solvent is preferably 5% - 9% (W / V, g / mL); the concentration of sodium alginate in the solvent is preferably 2% - 4% (W / V, g / mL); Preferably, the additive is activated carbon; the concentration of activated carbon in the solvent is preferably 0.5% - 1.5% (W / V, g / mL); Preferably, the mass ratio of polyethylene glycol, sodium alginate and activated carbon is 7:3:1.5; Preferably, the crosslinking agent is a saturated boric acid solution containing calcium chloride; the concentration of calcium chloride is 2 - 5% (W / V, g / mL); Preferably, the volume ratio of the crosslinking agent to the solvent is 0.5 - 2:1; Preferably, the temperature of the gelation reaction is 2 - 4°C, and the time of the gelation reaction is 20 - 24 h.

5. A high-phosphorus and high-nitrogen seawater treatment system, characterized in that, It includes a micro-nano aeration unit, a microbial denitrification unit and a denitrification and phosphorus removal unit connected in sequence; the micro-nano aeration unit is used to provide an aerobic environment; the microbial denitrification unit contains the heterotrophic nitrification-aerobic denitrification bacterium described in claim 1; the denitrification and phosphorus removal unit includes at least one group of seaweed cultivation ponds.

6. The high-phosphorus and high-nitrogen seawater treatment system according to claim 5, characterized in that, The micro-nano aeration unit includes a motor, an air suction device, a micro-nano bubble diffusion device, a countercurrent mixer and a gas-liquid vortex device; the air suction device is used to convey air into the water body; the micro-nano bubble diffusion device, the countercurrent mixer and the gas-liquid vortex device are used to mix the water body.

7. The high-phosphorus and high-nitrogen seawater treatment system according to claim 5, characterized in that, A plurality of immobilized microbial pellets are arranged in the microbial denitrification unit, and the salt-tolerant heterotrophic nitrification-aerobic denitrification bacterium is immobilized on the immobilized microbial pellets.

8. The high-phosphorus and high-nitrogen seawater treatment system according to claim 7, wherein, The preparation method of the immobilized microbial pellets comprises the following steps: Disperse the embedding agent and the additive in the solvent and completely dissolve them; then mix with the bacterial suspension containing the heterotrophic nitrification-aerobic denitrification bacterium Halomonas hydrothermalis; finally, add the crosslinking agent and obtain the immobilized microbial pellets through a gelation reaction; Preferably, the embedding agent is a composition of polyethylene glycol and sodium alginate; the solvent is water; the concentration of polyethylene glycol in the solvent is preferably 5% - 9% (W / V, g / mL); the concentration of sodium alginate in the solvent is preferably 2% - 4% (W / V, g / mL); Preferably, the additive is activated carbon; the concentration of activated carbon in the solvent is preferably 0.5% - 1.5% (W / V, g / mL); Preferably, the mass ratio of polyethylene glycol, sodium alginate and activated carbon is 7:3:1.5; Preferably, the crosslinking agent is a saturated boric acid solution containing calcium chloride; the concentration of calcium chloride is 2% - 5% (W / V, g / mL); Preferably, the volume ratio of the crosslinking agent to the solvent is 0.5 - 2:1; Preferably, the temperature of the gelation reaction is 2 - 4°C, and the time of the gelation reaction is 20 - 24 h.

9. The high-phosphorus and high-nitrogen seawater treatment system according to claim 5, characterized in that The seaweeds cultured in the seaweed culture pond are Ulva lactuca and / or Sargassum horneri; Preferably, the seaweeds are a mixture of Ulva lactuca and Sargassum horneri cultured in a mass ratio of 2 - 4:1; preferably, the culture density of the seaweeds is 8 - 10 g / L.

10. Application of the treatment system according to any one of claims 5 - 9 in treating seawater with high phosphorus and high nitrogen.

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