Aquaculture wastewater recycling system and method based on microbial purification

Abstract

The invention belongs to the technical field of aquaculture, and provides an aquaculture wastewater recycling system and method based on microbial purification, and the method comprises the following steps: a wastewater collection unit collects wastewater generated in an aquaculture process, and performs pretreatment; the microbiological treatment unit is used for screening out microbial strains and carrying out batch treatment on the wastewater; the deep treatment unit performs electrochemical synergistic oxidation through a titanium-based ruthenium-iridium coating anode and a stainless steel cathode, and stimulates hydroxyl free radicals; the water quality monitoring and regulating unit monitors water quality indexes in real time; the cyclic utilization unit is used for storing the treated standard water through a water storage pond and conveying the water in the water storage pond back to the culture pond; the auxiliary unit is used for controlling various environmental factors in the microbiological treatment process and constructing a microbial strain growth environment; according to the invention, pollutants in the aquaculture wastewater are effectively removed through the metabolism of microorganisms, the cyclic utilization of water resources is realized, the culture cost is reduced, and the environmental pollution is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquaculture, and specifically relates to an aquaculture wastewater recycling system and method based on microbial purification. Background Art

[0002] At present, with the booming development of the aquaculture industry, its contribution to the global food supply and economic growth is becoming increasingly significant. However, at the same time, the problems brought about by the discharge of aquaculture wastewater are becoming increasingly severe, becoming a key factor restricting the sustainable development of the industry; aquaculture wastewater usually contains high concentrations of organic matter, nitrogen, phosphorus and pathogenic microorganisms. If directly discharged without treatment, it will cause serious damage to the water body and ecological environment.

[0003] However, the traditional aquaculture mode is mostly extensive, and the means of treating aquaculture wastewater are extremely limited. Many farms directly discharge untreated or simply treated wastewater into the surrounding natural water bodies. These wastewaters are rich in a large amount of organic matter, such as residual bait, excreta of cultured organisms, etc. The chemical oxygen demand (COD) and biochemical oxygen demand (BOD) values often far exceed the environmental carrying capacity standards. After the discharge of untreated high-concentration organic wastewater, it will quickly consume the dissolved oxygen in the water body, resulting in hypoxia in the water body, causing aquatic animals and plants to suffocate and die due to hypoxia, seriously damaging the water ecological balance. Traditional chemical treatment methods such as flocculation, precipitation and disinfection usually require the addition of a large amount of chemical agents, resulting in high operating costs, especially in large-scale farms. And the use of chemical agents sometimes causes secondary pollution problems. The treated wastewater may still contain harmful chemical substances and cannot meet the environmental discharge standards. Traditional physical treatment methods such as simple precipitation and filtration are difficult to effectively remove dissolved organic matter and microorganisms in the water, especially in high-load aquaculture wastewater. The removal rates of these methods are significantly reduced. At the same time, most farms rely on fresh water resources for aquaculture and do not effectively recycle the wastewater. This not only causes a huge waste of water resources, but also limits the expansion of the aquaculture scale in water-scarce areas. With the increasingly strict environmental protection requirements, the traditional aquaculture wastewater treatment methods are difficult to meet the sustainable development needs.

[0004] Therefore, the technical personnel in this field have proposed an aquaculture wastewater recycling system and method based on microbial purification, aiming to construct a synergistic purification system of directional domestication of composite bacteria groups and coupling of multi-stage biofilms, effectively remove pollutants in aquaculture wastewater, realize the recycling of water resources, reduce aquaculture costs, and reduce environmental pollution. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an aquaculture wastewater recycling system and method based on microbial purification to solve the problems raised in the background art.

[0006] According to the first aspect of the present disclosure, a system for recycling aquaculture wastewater based on microbial purification is proposed, including:

[0007] A wastewater collection unit for collecting wastewater generated during aquaculture and pre-treating the wastewater;

[0008] A microbial treatment unit for screening microbial strains for treating aquaculture wastewater, activating them, and batch-treating the wastewater under different oxygen environment conditions;

[0009] A deep treatment unit for performing electrochemical synergistic oxidation by means of a titanium-based ruthenium-iridium coated anode and a stainless steel cathode, and exciting hydroxyl radicals by a UVA-LED excitation device;

[0010] A water quality monitoring and regulation unit for real-time monitoring of water quality indicators during the microbial treatment process, adjusting the dosage of microorganisms according to the monitoring results, and supplementing fresh water to maintain stable water quality;

[0011] A recycling unit for storing the treated qualified water in a storage tank and transporting the water in the storage tank back to the aquaculture pond for recycling of water resources;

[0012] An auxiliary unit for assisting the water quality monitoring and regulation unit to control various environmental factors during the microbial treatment process and construct a growth environment for microbial strains.

[0013] Preferably, in the wastewater collection unit, the pre-treatment removes large-volume solid impurities in the wastewater by setting a grille, and through a grit chamber, inorganic particles including sand grains in the wastewater are separated by the principle of gravity sedimentation.

[0014] Preferably, the microbial treatment unit screens out anaerobic microorganisms and aerobic microorganisms. The anaerobic microorganisms are anaerobic bacteria, and the aerobic microorganisms are the constructed salt-tolerant composite flora, which is constructed from the genera Pseudomonas, Nitrospira, and Rhodobacter, and is composed of a bacterial number ratio of 3:2:1, and is loaded on a sodium alginate-zeolite composite carrier, and the porosity of the carrier is 72 ± 5%, and the particle size is 2 mm;

[0015] After activating the screened microbial strains, first, the pre-treated wastewater enters the anaerobic reactor. Under anaerobic conditions, the anaerobic microorganisms decompose the macromolecular organic matter in the wastewater into small molecular organic acids and methane. Then, the anaerobically treated wastewater flows into the aerobic biological pond and is fully mixed with the activated sludge in the pond. The aerobic microorganisms multiply in large numbers under sufficient oxygen conditions, decompose the organic matter in the water, and convert it into carbon dioxide and water;

[0016] After the wastewater passes through the anaerobic reactor and the aerobic biological pond, the wastewater flows into the biofilm reactor. Bacillus, photosynthetic bacteria microorganisms and honeycomb packing carriers are added into the biofilm reactor, so that the microorganisms attach and grow on the surface of the carrier to form a biofilm, and a quorum sensing inhibitor with a concentration of 0.05 - 0.1 mmol / L is added to regulate the metabolism of the biofilm. The wastewater enters the biofilm reactor and comes into full contact with the biofilm. The microorganisms on the biofilm adsorb and degrade the pollutants in the wastewater.

[0017] Preferably, under anaerobic conditions, the anaerobic reactor decomposes the macromolecular organic matter in the wastewater through anaerobic microorganisms, controls the pH value at 6.5 - 7.5, and maintains the temperature at 30°C - 35°C to keep the anaerobic microorganisms in the best activity. At the same time, the sludge accumulated at the bottom of the anaerobic reactor is regularly discharged.

[0018] The anaerobically treated wastewater flows into the aerobic biological pond. First, the aeration equipment is started to keep the dissolved oxygen content in the pond at 2 - 4 mg / L, and the sludge concentration in the aerobic biological pond is kept at 2000 - 4000 mg / L. At the same time, part of the activated sludge is refluxed to the front end of the aerobic biological pond to maintain the quantity and activity of the microorganisms in the pond.

[0019] The wastewater enters the biofilm reactor and comes into full contact with the biofilm. The thickness of the biofilm is controlled at 0.5 - 2 mm. When the biofilm shows aging and clogging, backwashing operation is carried out to remove the aged biofilm and enable the growth of a new biofilm.

[0020] Preferably, the advanced treatment unit conducts electrochemically assisted oxidation by using a titanium-based ruthenium-iridium coated anode and a stainless steel cathode, and the current density is 10 mA / cm 2 ; and it is coupled with electrolysis by a 365 nm UVA-LED to generate hydroxyl radicals.

[0021] The preparation process of the titanium-based ruthenium-iridium coated anode includes: using 0.1 mol / L RuCl3·3H2O and 0.02 mol / L IrCl3·xH2O as the precursor solution, calcining at 450°C for 1 h, and repeating the process 3 times.

[0022] The superposition effect of TiO2 photocatalytic reaction excited by a 365 nm, 10 mW / cm 2 UVA-LED and the generation of ·OH by electrolysis.

[0023] Preferably, the auxiliary unit monitors and adjusts the temperature, pH value and oxygen conditions in different treatment stages of the microbial treatment unit in real time, and at the same time supplements the carbon source, nitrogen source and phosphorus source required for the growth and reproduction of microorganisms. According to different treatment stages, it adjusts the gas supply mode and controls the oxygen concentration in a zoning manner.

[0024] According to the second aspect of the present disclosure, a method for recycling aquaculture wastewater based on microbial purification is also proposed, which is applied to the first aspect of the present disclosure and includes the following steps:

[0025] S1. Introduce the wastewater generated during the aquaculture process into the wastewater collection unit through a pipeline system. Remove large solid impurities in the wastewater by setting a grille. Subsequently, the wastewater enters a grit chamber, and inorganic particles including sand grains in the wastewater are separated using the principle of gravitational sedimentation.

[0026] S2. Transport the pretreated wastewater to an anaerobic reactor for treatment under anaerobic conditions, and regularly discharge the sludge accumulated at the bottom of the anaerobic reactor.

[0027] S3. Let the anaerobically treated wastewater flow into an aerobic biological pond. Start the aeration equipment, control the dissolved oxygen content, and partially return the activated sludge to the front end of the aerobic biological pond.

[0028] S4. After the anaerobically treated wastewater is treated in the aerobic biological pond, the wastewater continues to flow into a biofilm reactor, where it comes into full contact with the microbial biofilm attached to the surface of the honeycomb-shaped packing carrier. The microorganisms on the biofilm adsorb and degrade the pollutants in the wastewater.

[0029] S5. Electrochemically co-oxidize the wastewater passing through the microbial treatment unit by means of a titanium-based ruthenium-iridium coated anode and a stainless steel cathode, with a current density of 10 mA / cm 2 ; and couple with a 365 nm UVA-LED for electrolysis to excite hydroxyl radicals.

[0030] S6. Use an on-line sensor to monitor the water quality indicators in real time, and automatically adjust the dosage of microorganisms, aeration intensity, return sludge volume, and supplement fresh water according to the monitoring data to maintain the water quality stability.

[0031] S7. Store the up-to-standard water after advanced treatment in a storage tank, and transport the water in the storage tank back to the aquaculture pond through a pipeline for recycling of water resources.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. Through the collaborative work of multiple units, the present invention comprehensively purifies wastewater. Through the synergistic effect of anaerobic microorganisms and aerobic microorganisms, the anaerobic microorganisms decompose macromolecular organic matter, and the aerobic microorganisms further degrade organic matter and denitrify. The biological membrane reactor strengthens the treatment effect. Combining the pretreatment of the grille and grit chamber, and the advanced treatment of electrochemical synergistic oxidation, it effectively removes residual pollutants and harmful microorganisms, making the wastewater meet the standard for recycling, significantly improving water quality; and by adopting the combined method of salt-tolerant composite bacteria-MFC-electrochemical synergistic-intelligent control, a coupling effect is generated, significantly improving the efficiency and removal rate of wastewater treatment and recycling.

[0034] 2. The salt-tolerant nitrifying bacteria, denitrifying bacteria and heterotrophic bacteria screened by the present invention form a microbial aggregate with complementary functions, realizing the step-by-step degradation of pollutants, creating a good environment for aquaculture organisms, reducing the occurrence of diseases, reducing the mortality rate of aquaculture organisms, improving the aquaculture yield and quality, increasing economic benefits, realizing the recycling of water resources, reducing the dependence on fresh water resources, and reducing the cost of aquaculture water. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a block diagram of an aquaculture wastewater recycling system based on microbial purification according to the present invention;

[0036] Figure 2 is a flowchart of a method for recycling aquaculture wastewater based on microbial purification according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] The following further describes in detail the embodiments of the present invention in conjunction with the drawings and examples. The following examples are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0038] As shown in the Figure 1 accompanying drawings:

[0039] Example 1: The present invention provides an aquaculture wastewater recycling system based on microbial purification, including:

[0040] A wastewater collection unit for collecting wastewater generated during aquaculture and performing pretreatment on the wastewater; the pretreatment in the wastewater collection unit removes large-volume solid impurities in the wastewater, such as residual bait, feces, etc., through a grille to reduce the load of subsequent treatment units, and through a grit chamber, using the principle of gravity sedimentation, further separates inorganic particles including sand grains in the wastewater to improve the wastewater treatment efficiency.

[0041] The microbial treatment unit is a detachable spiral tube reactor (inner diameter 20 cm, pitch 30 cm, residence time 4 - 6 h), and a microbial fuel cell (MFC) is set at the outlet of the microbial treatment unit to generate electricity using metabolic electrons (output voltage ≥ 0.4 V); by screening microbial strains for aquaculture wastewater treatment and activating them, batch treatment of the wastewater is carried out under different oxygen environmental conditions; in the microbial treatment unit, anaerobic and aerobic microorganisms are screened out. The anaerobic microorganism is an anaerobic bacterium, and the aerobic microorganism is a salt-tolerant composite flora, which is constructed from Pseudomonas : Nitrospira : Rhodobacter = 3:2:1 and is loaded on a sodium alginate-zeolite composite carrier, the porosity of the carrier is 72 ± 5%, and the particle size is 2 mm;

[0042] The salt-tolerant composite flora is screened by the salinity gradient method. Specifically, it is continuously passaged and cultured 10 times at a salinity of 5‰ → 30‰, strains with a growth rate > 0.8 / h are screened, and the specific degradation rate is measured under the conditions of COD 800 mg / L and NH3-N 100 mg / L, and a pollutant tolerance experiment is carried out.

[0043] The sodium alginate-zeolite composite carrier is prepared by compounding sodium alginate (SA) and acid-modified zeolite (H-ZSM5) at a mass ratio of 2:1. After the zeolite is treated with 0.5 mol / L HCl at 80℃ for 4 h, it is blended and crosslinked with an SA solution (2% w / v). Measured by the mercury intrusion method, the porosity of the carrier is 72.3%, and the cell loading reaches 1.2×10 8 CFU / g carrier.

[0044] After activating the screened microbial strains, first, the pretreated wastewater enters the anaerobic reactor. Under anaerobic conditions, the anaerobic microorganisms decompose the macromolecular organic matter in the wastewater into small molecular organic acids and methane. Then, the anaerobically treated wastewater flows into the aerobic biological pool and is fully mixed with the activated sludge in the pool. The aerobic microorganisms multiply in large numbers under sufficient oxygen conditions, decompose the organic matter in the water, and convert it into carbon dioxide and water;

[0045] After the wastewater passes through the anaerobic reactor and the aerobic biological pool, the wastewater flows into the biofilm reactor. Bacillus spp., photosynthetic bacteria microorganisms, and honeycomb-shaped filler carriers are added to the biofilm reactor, so that the microorganisms attach and grow on the surface of the carrier to form a biofilm, and 0.05 - 0.1 mmol / L quorum sensing inhibitor is added to regulate the metabolism of the biofilm. The quorum sensing inhibitor is furanone. The wastewater enters the biofilm reactor and comes into full contact with the biofilm. The microorganisms on the biofilm adsorb and degrade the pollutants in the wastewater; The wastewater enters the biofilm reactor and comes into full contact with the biofilm. The microorganisms on the biofilm adsorb and degrade the pollutants in the wastewater.

[0046] Under anaerobic conditions, the anaerobic reactor decomposes the macromolecular organic matter in the wastewater through anaerobic microorganisms, controls the pH value between 6.5 and 7.5, and maintains the temperature between 30°C and 35°C to keep the anaerobic microorganisms in the best activity. At the same time, the sludge accumulated at the bottom of the anaerobic reactor is regularly discharged to prevent sludge aging from affecting the treatment effect;

[0047] The wastewater after anaerobic treatment flows into the aerobic biological pool. First, by starting the aeration equipment, the dissolved oxygen content in the pool is maintained at 2-4 mg / L, and the sludge concentration in the aerobic biological pool is maintained at 2000-4000 mg / L. At the same time, part of the activated sludge is refluxed to the front end of the aerobic biological pool to maintain the quantity and activity of microorganisms in the pool;

[0048] The wastewater enters the biofilm reactor, and the microorganisms attach and grow on the surface of the carrier to form a biofilm, further degrading the pollutants in the wastewater. The wastewater is in full contact with the biofilm, and the biofilm thickness is controlled at 0.5-2 mm. When the biofilm shows aging and clogging, backwashing operation is carried out to remove the aged biofilm and promote the growth of the new biofilm.

[0049] The advanced treatment unit conducts electrochemically synergistic oxidation by using a titanium-based ruthenium-iridium coated anode and a stainless steel cathode, and the current density is 10 mA / cm 2 ; and it is coupled with electrolysis by a 365 nm UVA-LED to excite hydroxyl radicals;

[0050] The preparation process of the titanium-based ruthenium-iridium coated anode includes: using 0.1 mol / L RuCl3·3H2O and 0.02 mol / L IrCl3·xH2O as the precursor solution, and obtaining it by calcining at 450°C for 1 h and cycling 3 times;

[0051] The superposition effect of TiO2 photocatalytic reaction excited by a 365 nm, 10 mW / cm 2 UVA-LED and the electrolysis to generate ·OH. Through efficacy verification, the detection of ·OH concentration is carried out by the terephthalic acid fluorescence probe method, the peak intensity is increased by 2.3, and the COD removal amount per unit energy consumption is 1.24 g COD / (kWh), which is increased by 67% compared with the traditional electrolysis method.

[0052] The water quality monitoring and regulation unit is used to monitor the water quality indicators in the microorganism treatment process in real time, adjust the dosage of microorganisms according to the monitoring results, and supplement fresh water to keep the water quality stable, so as to ensure the stability and controllability of the wastewater treatment process; use the LSTM neural network model to predict the water quality change trend, and upload the water quality data to the blockchain in real time to generate an immutable treatment log. Its data upload writes the hash value of the water quality parameters into Hyperledger Fabric every 15 minutes, and its smart contract automatically triggers an alarm using the set threshold.

[0053] A recycling unit is used to store the treated up-to-standard water in a storage tank and convey the water in the storage tank back to the aquaculture pond, realizing the recycling of water resources, thereby saving water resources, reducing aquaculture costs, and also helping to reduce environmental pollution caused by wastewater discharge;

[0054] An auxiliary unit is used to assist the water quality monitoring and regulation unit to control various environmental factors during the microbial treatment process and construct a growth environment for microbial strains. The auxiliary unit monitors and adjusts the temperature, pH value, and oxygen conditions at different treatment stages in the microbial treatment unit in real time, and at the same time supplements the carbon source, nitrogen source, and phosphorus source required for the growth and reproduction of microorganisms. According to different treatment stages, it adjusts the gas supply mode and controls the oxygen concentration in a zoning manner, thereby optimizing the wastewater treatment effect.

[0055] By adopting a combined method of salt-tolerant composite bacteria-MFC-electrochemical synergy-intelligent control, a coupling effect is generated, significantly improving the efficiency and removal rate of wastewater treatment and recycling.

[0056] Example 2: The present invention provides a method for recycling aquaculture wastewater based on microbial purification, including the following steps:

[0057] S1. The wastewater generated during the aquaculture process is introduced into the wastewater collection unit through a pipeline system. Large solid impurities in the wastewater are removed by setting a grille, and then the wastewater enters the grit chamber, and inorganic particles including sand grains in the wastewater are separated by using the principle of gravity sedimentation;

[0058] S2. The pretreated wastewater is conveyed to an anaerobic reactor for treatment under anaerobic conditions, and the sludge accumulated at the bottom of the anaerobic reactor is discharged regularly;

[0059] S3. The anaerobically treated wastewater flows into the aerobic biological pond, the aeration equipment is started, the dissolved oxygen content is controlled, and part of the activated sludge is refluxed to the front end of the aerobic biological pond;

[0060] S4. After the anaerobically treated wastewater is treated in the aerobic biological pond, the wastewater continues to flow into the biofilm reactor and comes into full contact with the microbial biofilm attached to the surface of the honeycomb-shaped packing carrier. The microorganisms on the biofilm adsorb and degrade the pollutants in the wastewater;

[0061] S5. The wastewater passing through the microbial treatment unit is subjected to electrochemical synergy oxidation by means of a titanium-based ruthenium-iridium coated anode and a stainless steel cathode, and the current density is 10 mA / cm 2 ; and is coupled with electrolysis by a 365 nm UVA-LED to generate hydroxyl radicals;

[0062] S6. Use on-line sensors to monitor water quality indicators in real time, and automatically adjust the dosage of microorganisms, aeration intensity, return sludge volume, and supplement fresh water according to the monitoring data to maintain stable water quality;

[0063] S7. Store the up-to-standard water after advanced treatment in a storage tank, and transport the water in the storage tank back to the aquaculture pond through pipelines for recycling of water resources.

[0064] Experimental example: The object to be treated is the aquaculture wastewater of Litopenaeus vannamei, with a scale of 100 m 3 / d; the influent water quality is COD 320 ± 45 mg / L, NH3-N 38 ± 6 mg / L, and salinity 18 - 25‰;

[0065] Operate the aquaculture wastewater recycling system based on microbial purification provided in the first embodiment, and the operation results are shown in the following table:

[0066] Index Effluent concentration Removal rate COD 28mg / L 91.3％ <![CDATA[NH3-N]]> 0.9mg / L 97.6％ Conductivity 2.1mS / cm -

[0067] Through comparative experiments, the control group adopted the traditional A / O process + sand filtration method, and the obtained data are shown in the following table:

[0068] Parameter Control group Experimental group Improvement range <![CDATA[Energy consumption (kWh / m 3 )]]> 2.1 0.9 57％↓ Floor area 0.8 0.35 56％↓ Ability to resist salinity fluctuations ＜15‰ 10-30‰ 100％↑

[0069] The above results show that the present invention adopts the combined method of salt-tolerant composite bacteria-MFC-electrochemical synergy-intelligent control. Compared with the traditional process, the wastewater treatment effect has been significantly improved. Through the constructed synergistic purification system of directional domestication of composite bacteria and multi-stage biofilm coupling, the removal rates of toxic substances such as ammonia nitrogen and nitrite can be increased to more than 95%, and at the same time, organic suspended solids can be efficiently captured through biological flocculation. After field verification, the system can keep the recycling rate of circulating water stable above 80%, reduce energy consumption by 42% compared with the traditional physical filtration method, and has the characteristics of self-balanced ecological maintenance, effectively solving industry problems such as rapid water quality deterioration and chemical agent residues in high-density aquaculture.

[0070] Importantly, it should be noted that the construction and arrangement of the present application shown in multiple different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who refer to this disclosure should easily understand that many modifications are possible without substantially departing from the novel teachings and advantages of the subject matter described in this application (e.g., the dimensions, scales, structures, shapes, and proportions of various elements, as well as parameter values (such as temperature, pressure, etc.), installation arrangements, use of materials, color, orientation changes, etc.). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature, number, or position of discrete elements may be altered or changed. Accordingly, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means-plus-function" clause is intended to cover the structures that perform the recited function herein, and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the present invention is not limited to a particular embodiment, but extends to various modifications that still fall within the scope of the appended claims.

[0071] In addition, in order to provide a concise description of the exemplary embodiments, all features of the actual embodiments may not be described (i.e., those features that are not relevant to the currently contemplated best mode of carrying out the present invention or those features that are not relevant to implementing the present invention).

[0072] It should be understood that in the development of any actual implementation, in any engineering or design project, a large number of specific implementation decisions may be made. Such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from this disclosure, without excessive experimentation, such development efforts will be a routine task of design, manufacturing, and production.

[0073] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A system for recycling aquaculture wastewater based on microbial purification, characterized in that: include: A wastewater collection unit, used to collect wastewater generated during aquaculture and pre-treat the wastewater; Microbial treatment unit, used to screen out microbial strains for aquaculture wastewater treatment, activate them, and batch treat wastewater under different oxygen environment conditions; A deep treatment unit for electrochemical synergistic oxidation by means of a titanium-based ruthenium-iridium coated anode and a stainless steel cathode, and excitation of hydroxyl radicals by a UVA-LED excitation device; The water quality monitoring and control unit is used to monitor the water quality indicators in the microbial treatment process in real time, and adjust the dosage of microorganisms according to the monitoring results, as well as add fresh water to maintain stable water quality; The recycling unit is used to store the treated water that meets the standards in a water storage tank and transport the water in the water storage tank back to the breeding pond to recycle the water resources; The auxiliary unit is used to assist the water quality monitoring and control unit, control various environmental factors in the microbial treatment process, and construct a growth environment for microbial strains.

2. The aquaculture wastewater recycling system based on microbial purification as claimed in claim 1, characterized in that: The wastewater collection unit pre-treats the wastewater by setting a grid to remove large solid impurities, and separates inorganic particles including sand particles in the wastewater by using a grit chamber and gravity sedimentation principle.

3. The aquaculture wastewater recycling system based on microbial purification as claimed in claim 1, characterized in that: The microbial treatment unit screens out anaerobic microorganisms and aerobic microorganisms, wherein the anaerobic microorganisms are anaerobic bacteria, and the aerobic microorganisms are constructed salt-tolerant composite bacterial flora, which are constructed from Pseudomonas, Nitrospira and Rhodobacter, with a bacterial count ratio of 3:2:1, and are loaded on a sodium alginate-zeolite composite carrier, wherein the carrier has a porosity of 72±5% and a particle size of 2 mm; After the selected microbial strains are activated, the pre-treated wastewater is first fed into an anaerobic reactor. Under anaerobic conditions, anaerobic microorganisms decompose the macromolecular organic matter in the wastewater into small molecular organic acids and methane. The anaerobic wastewater then flows into an aerobic biological pool and is fully mixed with the activated sludge in the pool. Aerobic microorganisms multiply in large quantities under sufficient oxygen conditions, decompose the organic matter in the water, and convert it into carbon dioxide and water. After the wastewater passes through the anaerobic reactor and the aerobic biological pool, it flows into the biofilm reactor. Bacillus, photosynthetic bacterial microorganisms and honeycomb filler carriers are added to the biofilm reactor to allow the microorganisms to attach and grow on the surface of the carrier to form a biofilm. 0.05-0.1mmo l / L quorum sensing inhibitor is added to regulate the metabolism of the biofilm. The wastewater enters the biofilm reactor and is fully in contact with the biofilm. The microorganisms on the biofilm adsorb and degrade the pollutants in the wastewater.

4. The aquaculture wastewater recycling system based on microbial purification as claimed in claim 3, characterized in that: The anaerobic reactor decomposes macromolecular organic matter in the wastewater under anaerobic conditions by anaerobic microorganisms, controls the pH value at 6.5-7.5, and maintains the temperature at 30°C-35°C to keep the anaerobic microorganisms at their best activity, while regularly discharging the sludge accumulated at the bottom of the anaerobic reactor; The anaerobic wastewater flows into the aerobic biological pool, and the aeration equipment is started to maintain the dissolved oxygen content in the pool at 2-4 mg / L, and the sludge concentration in the aerobic biological pool is maintained at 2000-4000 mg / L. At the same time, part of the activated sludge is returned to the front end of the aerobic biological pool to maintain the number and activity of microorganisms in the pool; The wastewater enters the biofilm reactor and is fully in contact with the biofilm. The thickness of the biofilm is controlled at 0.5-2 mm. When the biofilm becomes aged or blocked, a backwashing operation is performed to remove the aged biofilm and allow a new biofilm to grow.

5. The aquaculture wastewater recycling system based on microbial purification as claimed in claim 1, characterized in that: The deep treatment unit uses a titanium-based ruthenium-iridium coated anode and a stainless steel cathode for electrochemical synergistic oxidation, with a current density of 10 mA / cm 2 ; And through 365nm UVA-LED coupled with electrolysis, hydroxyl radicals are excited; The preparation process of the titanium-based ruthenium-iridium coating anode includes: using 0.1 mol / L RuCl3·3H2O and 0.02 mol / L IrCl3·xH2O as precursor solutions, calcining at 450°C for 1 hour, and cycling for 3 times to obtain the anode; Pass 365nm, 10mW / cm 2 The UVA-LED stimulates the photocatalytic reaction of TiO2, which has a superimposed effect with the electrolysis to produce ·OH.

6. The aquaculture wastewater recycling system based on microbial purification as claimed in claim 1, characterized in that: The auxiliary unit monitors and adjusts the temperature, pH value and oxygen conditions of different treatment stages in the microbial treatment unit in real time, while replenishing the carbon source, nitrogen source and phosphorus source required for the growth and reproduction of microorganisms. According to different treatment stages, the gas supply method is adjusted and the oxygen concentration is controlled in a zoning manner.

7. A method for recycling aquaculture wastewater based on microbial purification, applied to the aquaculture wastewater recycling system according to claims 1 to 6, characterized in that: The following steps are involved: S1. The wastewater generated during aquaculture is introduced into the wastewater collection unit through a pipe system, and a grid is set to remove large solid impurities in the wastewater. The wastewater then enters a grit chamber, and inorganic particles including sand in the wastewater are separated by gravity settling principle; S2, transporting the pretreated wastewater to the anaerobic reactor for treatment under anaerobic conditions, and regularly discharging the sludge accumulated at the bottom of the anaerobic reactor; S3, the wastewater after anaerobic treatment flows into the aerobic biological pool, the aeration equipment is started, the dissolved oxygen content is controlled, and part of the activated sludge is returned to the front end of the aerobic biological pool; S4. After the anaerobic wastewater is treated in the aerobic biological pool, it continues to flow into the biofilm reactor and fully contacts with the microbial biofilm attached to the surface of the honeycomb filler carrier. The microorganisms on the biofilm adsorb and degrade the pollutants in the wastewater. S5. The wastewater after the microbial treatment unit is electrochemically oxidized by a titanium-based ruthenium-iridium coated anode and a stainless steel cathode at a current density of 10 mA / cm 2 ; And through 365nm UVA-LED coupled with electrolysis, hydroxyl radicals are excited; S6. Use online sensors to monitor water quality indicators in real time, and automatically adjust the amount of microorganisms, aeration intensity, return sludge volume, and fresh water replenishment based on the monitoring data to maintain stable water quality; S7. Store the deeply treated water that meets the standards in a water storage tank, and transport the water in the water storage tank back to the breeding pond through a pipeline to recycle water resources.

Images