Mariculture tail water treatment process based on multistage synergy and ecological restoration

Abstract

The invention provides a mariculture tail water treatment process based on multi-stage synergy and ecological restoration, and solves the technical problems of high energy consumption, generation of toxic intermediate products and high requirements on wastewater components due to the adoption of an electrode catalytic oxidation module as a core technology in the existing process. The tail water treatment process comprises the following steps: S1, introducing mariculture tail water into an adjusting tank to finish homogenization treatment; s2, introducing effluent of the adjusting tank into an air flotation system, adding an aluminum salt phosphorus removal agent and a coagulant aid, and removing total phosphorus and suspended solids; s3, effluent of the air flotation system is introduced into a salt-tolerant DN biochemical stabilization system, and nitrate nitrogen in the mariculture tail water is removed through denitrification nitrogen removal treatment of a microbial filler attached with salt-tolerant denitrifying bacteria; s4, the effluent of the salt-tolerant DN biochemical stabilization system is introduced into a whole-chain-layer ecological collaborative purification system, and biological purification is completed; and S5, guiding out the water subjected to biological purification to complete the treatment of the mariculture tail water. The method can be widely applied to the technical field of sewage treatment.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to a marine aquaculture tailwater treatment process based on multi-stage coordination and ecological restoration. Background Art

[0002] Marine aquaculture mainly refers to the production activities of cultivating marine aquatic economic plants and animals on coastal beaches. With the rapid development of the aquaculture industry, the problem of tailwater pollution has followed. The tailwater contains a large amount of organic matter such as leftover bait and feces, as well as harmful substances such as ammonia nitrogen and nitrite. If the tailwater is discharged directly, it will cause serious pollution to the marine ecological environment.

[0003] At present, the marine aquaculture tailwater treatment process uses the electrode catalytic oxidation module as the core process. Although the process flow and operation are simple, there are still the following three main deficiencies:

[0004] (1) High energy consumption: Electrochemical water treatment technology requires a large amount of electrical energy to drive electrode reactions. Especially when treating high-concentration organic wastewater, the energy consumption problem is particularly prominent.

[0005] (2) Toxic intermediates may be produced: In the process of degrading organic pollutants, the electrode catalytic oxidation module may generate some toxic intermediates. For example, when treating certain organic wastewater, harmful substances such as chlorinated organics may be produced.

[0006] (3) High requirements for wastewater composition: When the chloride ion content in the wastewater is too high, difficult-to-degrade intermediate substances such as organic chlorine may be generated, inhibiting the wastewater treatment effect. Summary of the invention

[0007] The purpose of the present invention is to solve the deficiencies of the above-mentioned technologies and to provide a marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration. On the basis of ensuring that environmental discharge standards are met, a new model of ecological green development of marine aquaculture tailwater treatment is achieved through multi-stage synergy technology.

[0008] To this end, the present invention provides a marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration, comprising the following steps:

[0009] Step S1. Pass the seawater aquaculture tail water into the regulating tank to complete the homogenization treatment.

[0010] Step S2: The effluent from the regulating tank is introduced into the flotation system, and an aluminum salt dephosphorizer and a coagulant are added to remove the total phosphorus and suspended solids in the marine aquaculture tail water.

[0011] Step S3: The effluent from the flotation system is passed into the salt-tolerant DN biochemical stabilization system, and is subjected to denitrification treatment by a microbial filler attached with salt-tolerant denitrifying bacteria to remove nitrate nitrogen from the tail water of seawater aquaculture.

[0012] Step S4. The effluent from the salt-tolerant DN biochemical stabilization system is passed into the full-chain ecological synergistic purification system to complete biological purification.

[0013] Step S5: The purified water in the full-chain ecological collaborative purification system is exported to complete the treatment of seawater aquaculture tail water.

[0014] Preferably, in step S2, the dissolved gas pressure is 0.3-0.5 MPa, and the hydraulic load is 5 m 3 / m 2 ·h.

[0015] Preferably, in step S2, the aluminum salt dephosphorization agent is polyaluminum chloride, and the coagulant aid is a polymer coagulant aid; the dosage of the aluminum salt dephosphorization agent is controlled at 40-50 mg / L, and the dosage of the coagulant aid is controlled at 5-6 mg / L.

[0016] Preferably, in step S3, the specific surface area of ​​the microbial filler is ≥ 800 m 2 / m 3 .

[0017] Preferably, in step S3, nano-oxygenation is performed on the seawater aquaculture tail water, and the dissolved oxygen is controlled at 1.5-3 mg / L.

[0018] Preferably, in step S4, the full-chain ecological synergistic purification system includes a reservoir, seawater aquaculture tail water is introduced into the reservoir, salt-tolerant algae are planted at the bottom of the reservoir, marine shellfish and aquatic herbivorous marine fish and shrimp are stocked in the seawater aquaculture tail water, and ecological floating islands are placed on the surface of the seawater aquaculture tail water.

[0019] Preferably, in step S4, the density of marine shellfish is 50 to 100 per m 3 , the coverage rate of salt-tolerant algae on the bottom of the reservoir is ≥60%.

[0020] Preferably, the air flotation system is respectively equipped with a PAC dosing system and a PAM dosing system.

[0021] Preferably, the regulating tank, flotation system, salt-tolerant DN biochemical stabilization system, and full-chain ecological synergistic purification system are respectively installed with a COD online monitor, an ammonia nitrogen online monitor, and a pH online detector.

[0022] The beneficial effects of the present invention are as follows: the present invention provides a marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration, adopting a unique technical design idea. After the marine aquaculture tailwater enters the regulating tank, the flotation system is placed in front to preferentially remove suspended solids and total phosphorus; COD, ammonia nitrogen, total nitrogen and other pollutants are removed by the salt-tolerant DN biochemical stabilization system, and finally the water quality is further purified by the full-chain ecological synergistic purification system, and the water quality reaches the Class I seawater discharge standard, fundamentally solving the technical problems of the existing process using the electrode catalytic oxidation module as the core technology, with high energy consumption, the production of toxic intermediates, and high requirements for wastewater components. While constructing a new biological restoration model for marine aquaculture tailwater, the present invention realizes the resource utilization of marine aquaculture tailwater, and takes into account the landscape value of the restoration facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application.

[0024] Figure 1 The present invention is a flowchart of the process of treating seawater aquaculture tail water.

[0025] Markings in the figure: 1. Equalization tank, 2. Flotation system, 3. Salt-tolerant DN biochemical stabilization system, 4. Full-chain ecological synergistic purification system. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The methods used in the present invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercial products unless otherwise specified.

[0027] Treatment of tailwater from marine aquaculture is a systematic project that requires consideration of the nature of the aquaculture land, the quality of influent and effluent water, and daily operation and maintenance. When designing the treatment process, physical, chemical, biological and ecological management methods should be effectively combined to unify the effectiveness, long-term effectiveness, economy and ecological compatibility of tailwater treatment, and formulate a targeted process plan based on local conditions.

[0028] Most of the tail water from marine aquaculture is the flushing water after being filtered by the microfiltration machine of the aquaculture factory. After testing, the main indicators of water quality are: Chemical Oxygen Demand (COD Mn ): 10-40 mg / L, total nitrogen: 5-10 mg / L, total phosphorus: 0.3-1.5 mg / L, suspended solids (SS): 50-100 mg / L.

[0029] Most of the tail water of seawater aquaculture is washed water after filtering by microfiltration machine, and the suspended matter is mainly excessive bait and animal feces. The design idea of ​​the process scheme of the present invention is: Figure 1 As shown, after the marine aquaculture tail water enters the regulating pond 1, the flotation system 2 is considered to be placed in front to give priority to the removal of suspended solids and total phosphorus; then the COD and pollutants such as ammonia nitrogen and total nitrogen are removed through the salt-tolerant DN biochemical stabilization system 3, and finally the water quality is further purified through the full-chain ecological synergistic purification system 4, while creating an ecological leisure landscape. Therefore, the process scheme determined by the present invention is: the "SDN-multi-level ecosystem" process of regulating pond 1+flotation system 2+salt-tolerant DN biochemical stabilization system 3+full-chain ecological synergistic purification system 4, where SDN is the abbreviation of enhanced denitrification / nitrification (Simultaneous Denitrification and Nitrification). The total effluent design effluent water quality complies with the first-class seawater discharge standard ("Aquaculture Tail Water Discharge Standard" (DB46475-2023)): COD Mn ≤10mg / L, total nitrogen ≤3.5mg / L, SS ≤50mg / L, total phosphorus ≤0.5mg / L, pH6.0~9.0.

[0030] The salt-tolerant DN biochemical stabilization system 3 in the present invention is a biochemical treatment system for treating high-salt wastewater. It realizes efficient denitrification in a high-salt environment through salt-tolerant denitrifying bacteria, wherein DN is the abbreviation of denitrification in English, which refers to the denitrification process, thereby removing nitrate nitrogen in the wastewater and achieving the purpose of purifying water quality.

[0031] Example 1

[0032] The microbial filler used in the salt-tolerant DN biochemical stabilization system 3 can be a commercially available product, preferably a biofilm filler of the present invention, and its formula is as shown in Table 1:

[0033] Table 1 Raw material formula of Examples 1 to 3 Weight: %

[0034]

[0035] The method of the biological biofilm filler of the present invention comprises the following steps:

[0036] (1) Raw material pretreatment: The raw materials in Table 1 are respectively subjected to conventional drying, crushing and sieving to complete pretreatment; wherein the particle size of polypropylene is 100 mesh, the particle size of polyvinyl alcohol is 80 mesh, the particle size of sodium alginate is 80 mesh, the particle size of zeolite is 60 mesh, the particle size of 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzene is 100 mesh, and the particle size of calcium stearate is 100 mesh, and they are set aside;

[0037] (2) melt blending: weigh the raw materials pretreated in step (1) respectively, add them into a twin-screw extruder according to the ratio, perform melt blending and extrusion granulation, control the temperature at 180-220° C., and the rotation speed at 150-155 rpm to obtain granules;

[0038] (3) Injection molding: The granulated material is injection molded with a mold pressure of 80 MPa and a cooling time of 30 s to obtain a filler matrix;

[0039] (4) Surface treatment: The surface was treated by low-temperature plasma with a power of 180-220 W for 5 min, and the biofilm fillers described in Examples 1-3 were finally obtained.

[0040] In the above step (2), the temperature is strictly controlled at 180-220°C. If the temperature is lower than 180°C, the melting is not complete, resulting in uneven mixing of the materials. If the temperature is higher than 220°C, the polyvinyl alcohol may degrade, affecting the hydrophilicity.

[0041] Experimental test:

[0042] (1) Specific surface area test

[0043] Test method: BET nitrogen adsorption method.

[0044] At liquid nitrogen temperature, the adsorption of nitrogen by a substance is physical adsorption. By filling a known amount of nitrogen into the sample tube and measuring the resulting pressure drop, the molar mass of the adsorbed gas at adsorption equilibrium can be calculated. Using the isothermal adsorption-desorption curve and theoretical model, the specific surface area of ​​the sample can be calculated.

[0045] Testing instrument: specific surface area analyzer.

[0046] Test results:

[0047] Table 2 Test results of specific surface area of ​​biofilm fillers obtained in Examples 1 to 3

[0048] Example 1 Example 2 Example 3 <![CDATA[Specific surface area (m 2 / g)]]> 25.3 25.1 24.8

[0049] As shown in Table 2, the specific surface area of ​​the biofilm filler of the present invention is 24.8-25.3 m 2 / g, indicating that the filler has a large specific surface area and has the advantage of a higher microbial attachment area.

[0050] (2) Porosity test

[0051] Test method: mercury porosimetry.

[0052] Test standard: ASTM D4404-18.

[0053] Testing instrument: Mercury intrusion instrument.

[0054] Test results:

[0055] Table 3 Test results of porosity of biofilm fillers obtained in Examples 1 to 3

[0056] Example 1 Example 2 Example 3 Porosity (%) 77.8 78.5 78.1

[0057] As shown in Table 3, the porosity of the biofilm filler of the present invention is 77.8-78.5%, while the porosity of the existing product is ≤60%, indicating that the present invention has the advantage of high porosity.

[0058] (3) Mechanical strength test

[0059] Test method: tensile properties test.

[0060] Test standard: ASTM D638-22.

[0061] Testing instrument: universal material testing machine.

[0062] Test results:

[0063] Table 4 Test results of mechanical strength of biofilm fillers obtained in Examples 1 to 3

[0064] Example 1 Example 2 Example 3 Tensile strength(MPa) 42.5 42 41.8 Elongation at break (%) 12.5 13.2 13.8

[0065] As shown in Table 4, the tensile strength of the biofilm filler of the present invention is 41.8-42.5 MPa, and the elongation at break is 12.5-13.8%, indicating that the present invention has the advantage of high mechanical strength.

[0066] (4) Corrosion resistance test

[0067] Test method: simulated seawater immersion test.

[0068] Simulated seawater formula: NaCl 3.5%, MgCl 2 0.5%, CaCl 2 0.1%, the balance is distilled water, pH is 8.0±0.2.

[0069] Test conditions: immersion temperature 25±1℃, immersion period 30 days, sample size 10mm×10mm×5mm.

[0070] Testing instruments: electronic balance, scanning electron microscope (SEM).

[0071] Test results:

[0072] Table 5 Test results of corrosion resistance of biofilm fillers prepared in Examples 1 to 3

[0073]

[0074] As shown in Table 5, the mass loss rate of the biofilm filler of the present invention is 0.80-0.85%, and there is no obvious corrosion on the surface, while the mass loss rate of the existing product is ≥3%, indicating that it has excellent seawater corrosion resistance.

[0075] (5) Hydrophilicity test

[0076] Test method: contact angle measurement.

[0077] Test standard: ISO 19403-2017.

[0078] The liquid is added or removed from the solid surface at a certain speed, the change in the drop shape is observed, and the angle between the drop edge and the solid surface is measured.

[0079] Testing instrument: contact angle meter.

[0080] Test results:

[0081] Table 6 Test results of hydrophilicity of biofilm fillers prepared in Examples 1 to 3

[0082] Example 1 Example 2 Example 3 Contact angle 26° 25° 27°

[0083] As shown in Table 6, the contact angles of the biofilm fillers prepared in Examples 1 to 3 are all ≤27°, compared with the contact angle of ≤40° of conventional products, the surface hydrophilicity of the present invention is excellent, which significantly promotes the initial attachment of microorganisms.

[0084] (6) Biological performance test

[0085] Test method: film forming effect test.

[0086] Biofilm detection method: Use laser confocal microscope to directly measure the biofilm thickness. The COD removal rate, ammonia nitrogen removal rate, total phosphorus removal rate and total nitrogen removal rate are based on the "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)". The potassium permanganate method is used to detect COD, the Nessler reagent method is used to detect ammonia nitrogen, the potassium persulfate digestion method is used to detect total nitrogen, and the ammonium molybdate spectrophotometry method is used to detect total phosphorus.

[0087] The biofilm fillers prepared in Examples 1 to 3 were respectively applied to a marine aquaculture tailwater treatment project. The pollutant removal rate was tested by extracting the biofilm fillers for biomass detection and detecting the inlet and outlet water indicators. The test results are as follows:

[0088] Table 7 Test results of biological properties of biofilm fillers prepared in Examples 1 to 3

[0089] Example 1 Example 2 Example 3 Film thickness (μm) 195 200 198 COD removal rate (%) 64.5 66.2 65.9 Ammonia nitrogen removal rate (%) 90.5 92.3 92.1 Total nitrogen removal rate (%) 76.3 76.2 77.2 Total phosphorus removal rate (%) 53.6 55.9 56.1

[0090] As shown in Table 7, the biofilm-forming filler of the present invention is used to treat seawater aquaculture tail water, and the COD removal rate is 64.5-66.2%, the ammonia nitrogen removal rate is 90.5-92.3%, the total nitrogen removal rate is 76.2-77.2%, and the total phosphorus removal rate is 53.6-56.1%, indicating that the biofilm-forming filler of the present invention has excellent biofilm-forming effect and outstanding treatment effect, and can achieve the target effect in seawater purification applications.

[0091] In summary, the biofilm filler of the present invention is based on polypropylene, and is modified by hydrophilic modification of polyvinyl alcohol and biological activity modification of sodium alginate, combined with zeolite enhancement and argon plasma surface treatment to achieve a specific surface area of ​​24.8-25.3 m 2 / g, porosity 77.8-78.5%, contact angle ≤27°, mass loss rate 0.80-0.85%, tensile strength 41.8-42.5Mpa, elongation at break 12.5-13.8%, COD removal rate 64.5-66.2%, ammonia nitrogen removal rate 90.5-92.3%, total nitrogen removal rate 76.2-77.2%, total phosphorus removal rate 53.6-56.1%. The preparation process of the biofilm filler achieves efficient production through melt blending and injection molding, and is suitable for large-scale application. The biofilm filler of the present invention has the advantages of large specific surface area, high porosity, good hydrophilicity, good biocompatibility, seawater corrosion resistance, high mechanical strength, etc. It can quickly form a biofilm in a seawater environment and maintain long-term stable operation, effectively remove pollutants in tail water, and can be widely used in seawater aquaculture tail water treatment.

[0092] It should be noted that:

[0093] (1) The hydrophilic modifier may be polyvinyl alcohol, or alternatively, polyethylene glycol or the like.

[0094] (2) The porous inorganic filler may be zeolite, or may be replaced by diatomaceous earth, talc or other porous inorganic fillers.

[0095] (3) The benzotriazole ultraviolet absorber may be 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, or may be replaced by a benzotriazole ultraviolet absorber such as 2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole.

[0096] (4) In the raw material pretreatment, drying, crushing and screening of each raw material are routine operations. For example, the drying temperature of polypropylene is controlled at 60-100°C; the particle size of each raw material is selected according to the actual situation.

[0097] (5) During the injection molding process, mold pressure, cooling time, etc. can be adjusted according to actual conditions.

[0098] Example 2

[0099] Depend on Figure 1 As shown, the present invention provides a marine aquaculture tail water treatment process based on multi-stage synergy and ecological restoration. According to the treatment sequence of marine aquaculture tail water, the marine aquaculture tail water mainly passes through a regulating tank 1, an air flotation system 2, a salt-tolerant DN biochemical stabilization system 3, and a full-chain ecological synergistic purification system 4 from upstream to downstream.

[0100] The marine aquaculture tail water treatment process includes the following steps:

[0101] Step S1. Pass the tail water of seawater aquaculture into the regulating tank 1 to complete the homogenization treatment; the regulating tank 1 is a concrete building, and its main function is to accommodate the tail water discharged by the farmers. A submersible mixer is installed in the tank to mix and homogenize the wastewater quality in the regulating tank 1, keep the wastewater relatively stable, and alleviate the impact on the subsequent flotation system 2.

[0102] Step S2. Pass the effluent from the regulating tank 1 into the flotation system 2, add aluminum salt dephosphorization agent and coagulant to remove total phosphorus and suspended solids in the seawater aquaculture tail water, wherein the total phosphorus in the seawater aquaculture tail water is controlled below 0.5 mg / L, and the suspended solids are controlled below 70 mg / L. Among them, the aluminum salt dephosphorization agent is polyaluminum chloride (PAC), and the dosage is controlled at 40-50 mg / L, and the coagulant is a polymer coagulant (PAM), and the dosage is controlled at 5-6 mg / L; the flotation system 2 is respectively equipped with a PAC dosing system and a PAM dosing system, which are used for the precise addition of PAC and PAM dosages, respectively. Since they are existing equipment, they will not be described here. The dissolved air pressure of the flotation system 2 is controlled at 0.3-0.5Mpa, and the hydraulic load is 5m 3 / m 2 ·h.

[0103] Step S3: The effluent from the flotation system 2 is passed into the water reservoir in the salt-tolerant DN biochemical stabilization system 3, which has been treated for seepage prevention. The water reservoir is provided with a microbial filler (i.e., a biomodule) attached with salt-tolerant denitrifying bacteria. The specific surface area of ​​the microbial filler is ≥ 800 m 2 / m 3 , the nitrate nitrogen in the marine aquaculture tail water is removed through denitrification treatment by the salt-tolerant denitrifying bacteria attached to the microbial filler; in addition, the micro-nano oxygenation equipment purchased by Hebei Xianhe Environmental Protection Technology Co., Ltd. is used to carry out nano-oxygenation in the marine aquaculture tail water, and the dissolved oxygen is controlled at 1.5-3 mg / L, which activates the activity of aerobic microorganisms and accelerates the decomposition of organic pollutants. At the same time, it can change the direction and speed of water flow, and combine with the biofilm group design to improve the sewage treatment efficiency.

[0104] Step S4. The effluent of the salt-tolerant DN biochemical stabilization system 3 is passed into the full-chain ecological collaborative purification system 4 to complete biological purification. The full-chain ecological collaborative purification system 4 includes a reservoir that has been treated for anti-seepage. Seawater aquaculture tail water is passed into the reservoir, and the dissolved oxygen in the seawater aquaculture tail water is controlled at 2.5-5 mg / L; salt-tolerant algae are planted at the bottom of the reservoir, and marine shellfish, aquatic herbivorous marine fish and shrimp are stocked in the seawater aquaculture tail water, and ecological floating islands are placed on the surface of the seawater aquaculture tail water; wherein, the coverage rate of salt-tolerant algae at the bottom of the reservoir is ≥60%, and needle-leaved kelp and different-branched Gracilaria are planted to absorb inorganic nitrogen salts and phosphates in the seawater aquaculture tail water, and can also be used as ornamental plants; the stocking density of marine shellfish is 50-100 / m 3 , release marine shellfish such as clams, cockles, cockles, and mussels to deal with suspended matter such as organic bait debris in the tail water of marine aquaculture; release aquatic herbivorous marine fish and shrimp such as bluefish and shrimp in the tail water of marine aquaculture to control the reproduction of salt-tolerant algae; the ecological floating islands are planted with salt-tolerant plants such as western sea asparagus and winged saltwort, which play an important role in water purification, ecological restoration, biological habitat construction and landscaping.

[0105] Step S5: The purified water in the full-chain ecological collaborative purification system 4 is exported to complete the treatment of seawater aquaculture tail water.

[0106] In addition, the regulating tank 1, flotation system 2, salt-tolerant DN biochemical stabilization system 3, and full-chain ecological synergistic purification system 4 are respectively installed with a COD online monitor, an ammonia nitrogen online monitor, and a pH online detector.

[0107] In the whole system, only the flotation system 2 will produce sludge, and the amount of sludge produced is greatly reduced compared with the ordinary biochemical system. The sludge produced by flotation is treated by the spiral sludge dewatering machine and then transported out for disposal as an auxiliary. The filtrate produced is returned to the front end of the regulating tank 1.

[0108] Water testing:

[0109] According to the detection method and detection frequency in Table 8 below, the chemical oxygen demand (COD) of the water quality of the marine aquaculture tail water in the regulating pond 1, the effluent of the air flotation tank, the effluent of the salt-tolerant DN stabilization pond system, and the effluent of the full-chain ecological synergy system were respectively measured. Mn ), ammonia nitrogen, total nitrogen, suspended solids (SS), total phosphorus, and pH detection. The test results are shown in Tables 9, 10, 11, and 12.

[0110] Table 8 Summary of water body detection names, test methods and frequencies

[0111]

[0112] Table 9 Summary of water quality testing of marine aquaculture tail water in regulating ponds

[0113]

[0114]

[0115] As shown in Table 9, after testing, the effluent quality of regulating pool 1 is controlled at: COD Mn It is 32.48-37.23 mg / L, ammonia nitrogen is 7.18-12.11 mg / L, total nitrogen is 8.48-13.92 mg / L, total phosphorus is 2.28-5.08 mg / L, SS is 181.25-263.43 mg / L, and pH is 7-7.8.

[0116] Table 10 Summary of water quality testing of flotation tank effluent

[0117]

[0118] As shown in Table 10, after testing, the effluent quality of the flotation system 2 is controlled at: COD Mn It is 29.68-34.64 mg / L, ammonia nitrogen is 8.5-11.49 mg / L, total nitrogen is 8.92-14.99 mg / L, total phosphorus is 0.25-0.74 mg / L, SS is 16.53-45.42 mg / L, and pH is 7.07-8.

[0119] Table 11 Summary of effluent quality testing of salt-tolerant DN biochemical stabilization system

[0120]

[0121] As shown in Table 11, after testing, the effluent quality of the salt-tolerant DN biochemical stabilization system 3 is controlled at: COD Mn It is 8.55-14.24 mg / L, ammonia nitrogen is 0.12-1.29 mg / L, total nitrogen is 1.34-4.94 mg / L, total phosphorus is 0.2-0.49 mg / L, SS is 9.03-13.97 mg / L, and pH is 7.08-7.96.

[0122] Table 12 Summary of effluent quality testing of the whole chain ecological collaborative purification system

[0123]

[0124] As shown in Table 12, after testing, the effluent of the full-chain ecological collaborative purification system 4 is stable and meets the discharge standards. The effluent quality is: COD MnThe COD content is 7.13-9.75 mg / L, the total nitrogen is 1.27-2.86 mg / L, the total phosphorus is 0.2-0.38 mg / L, the SS is 5.19-8.87 mg / L, and the pH value is 7.02-7.92, which meets the discharge standard of Class I seawater "Aquaculture Tail Water Discharge Standard" (DB46 475-2023). Mn The emission standards are ≤10mg / L, total nitrogen ≤3.5mg / L, SS ≤50mg / L, total phosphorus ≤0.5mg / L, and pH 6.0~9.0.

[0125] It can be seen that the present invention has achieved technological innovation. By integrating biological purification technology and ecological management technology, a set of efficient tail water treatment processes has been constructed. At the same time, ecological balance and resource recycling are specially considered in the system design, ensuring that the aquaculture tail water can meet environmental protection emission standards after treatment; the system also has certain landscaping functions and can coexist harmoniously with the surrounding environment, providing a new solution for the green development of marine aquaculture.

[0126] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration, characterized in that: The following steps are involved: Step S1. passing the seawater aquaculture tail water into the regulating tank to complete homogenization treatment; Step S2. passing the effluent from the regulating tank into the flotation system, adding an aluminum salt dephosphorizer and a coagulant to remove total phosphorus and suspended solids in the seawater aquaculture tail water; Step S3. passing the effluent of the flotation system into the salt-tolerant DN biochemical stabilization system, and removing nitrate nitrogen in the seawater aquaculture tail water through denitrification treatment by microbial fillers attached with salt-tolerant denitrifying bacteria; Step S4. passing the effluent of the salt-tolerant DN biochemical stabilization system into the full-chain ecological collaborative purification system to complete biological purification; Step S5: The purified water in the full-chain ecological collaborative purification system is exported to complete the seawater aquaculture tail water treatment.

2. A marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: In step S2, the dissolved gas pressure is 0.3-0.5 MPa, and the hydraulic load is 5 m 3 / m 2 ·h.

3. A marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: In step S2, the aluminum salt dephosphorization agent is polyaluminum chloride, and the coagulant aid is a polymer coagulant aid; the dosage of the aluminum salt dephosphorization agent is controlled at 40-50 mg / L, and the dosage of the coagulant aid is controlled at 5-6 mg / L.

4. A marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: In step S3, the specific surface area of ​​the microbial filler is ≥800m 2 / m 3 .

5. The marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: In the step S3, nano-oxygenation is performed on the seawater aquaculture tail water, and the dissolved oxygen is controlled at 1.5-3 mg / L.

6. The marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: In step S4, the full-chain ecological collaborative purification system includes a water reservoir, the seawater aquaculture tail water is introduced into the water reservoir, salt-tolerant algae are planted at the bottom of the water reservoir, marine shellfish and aquatic herbivorous marine fish and shrimp are stocked in the seawater aquaculture tail water, and ecological floating islands are placed on the surface of the seawater aquaculture tail water.

7. A marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 6, characterized in that: In step S4, the density of the marine shellfish is 50 to 100 per m 3 , the coverage rate of the salt-tolerant algae on the bottom of the reservoir is ≥ 60%.

8. The marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: The air flotation system is respectively equipped with a PAC dosing system and a PAM dosing system.

9. The marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: The regulating tank, the flotation system, the salt-tolerant DN biochemical stabilization system, and the full-chain ecological synergistic purification system are respectively installed with a COD online monitor, an ammonia nitrogen online monitor, and a pH online detector.

10. The marine aquaculture tailwater treatment process based on multi-stage synergy and ecological restoration according to claim 1, characterized in that: In step S3, the microbial filler is a biofilm filler, and its preparation raw materials include the following components by weight percentage: The method for producing biological biofilm filler comprises the following steps: melt blending and extruding the raw materials according to a proportion, and controlling the temperature at 180-220° C. to obtain granulated material; injection molding the granulated material to obtain a filler matrix; and surface treating the filler matrix with low-temperature plasma to obtain the biological biofilm filler.

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