A method for purifying aquaculture wastewater

Abstract

This application discloses a method for purifying aquaculture wastewater, relating to the field of wastewater treatment. The method includes the following steps: enzymatically hydrolyzing straw to obtain straw hydrolysate; adding the straw hydrolysate, microalgae, and fungal spores to the aquaculture wastewater for shaken co-cultivation; the microalgae include Chlorophyta algae, and the fungi include Aspergillus fungi. This application utilizes Chlorophyta algae and Aspergillus fungi to construct an algae-bacterial purification system in wastewater. The straw hydrolysate provides the algae and fungi with nutrients such as sugars and amino acids, and improves the stability of various nutrient content in the wastewater. Through this combined effect, the removal rate of ammonia nitrogen and total phosphorus in the wastewater is improved, and the phosphorus is converted into biomass.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment, and in particular to a method for purifying aquaculture wastewater. Background Technology

[0002] Currently, aquaculture wastewater is often treated by methods such as physical sedimentation, chemical coagulation, and conventional biological treatment. Among these, physical sedimentation and chemical coagulation usually require a large amount of chemical reagents and energy, which not only results in high treatment costs but also easily leads to secondary pollution. Conventional biological treatment methods, such as the traditional activated sludge process, require the addition of commercial carbon sources to maintain the activity of denitrifying bacteria, resulting in high treatment costs and low antibiotic reduction rates. Summary of the Invention

[0003] In view of the shortcomings of the aforementioned related technologies, this application provides a method for purifying aquaculture wastewater. This application utilizes a system of algae and Aspergillus bacteria to form an algae-bacterial purification system in the wastewater. Combined with straw hydrolysate, this system provides the algae and bacteria with nutrients such as sugars and amino acids, and improves the stability of the content of various nutrients in the wastewater. Through this combined effect, the removal rate of ammonia nitrogen and total phosphorus in the wastewater is improved, and the phosphorus is converted into biomass.

[0004] The method for purifying aquaculture wastewater provided in this application adopts the following technical solution:

[0005] A method for purifying aquaculture wastewater includes the following steps: taking straw and enzymatically hydrolyzing it to obtain straw hydrolysate; adding the straw hydrolysate, microalgae, and fungi to the aquaculture wastewater for shaken co-cultivation; wherein the microalgae include green algae, and the fungi include Aspergillus fungi.

[0006] Preferably, the microalgae include one or both of Chlorella sorokinensis and Scenedesmus.

[0007] Preferably, the fungus includes one or both of Aspergillus oryzae and Aspergillus niger.

[0008] Preferably, the microalgae is *Chlorella sorokinense*, and the fungus is *Aspergillus oryzae*.

[0009] Preferably, the inoculation concentration of the microalgae is 1×10⁻⁶. 6 Cells / mL - 1×10 7 The inoculation concentration of the fungus is 1 × 10⁶ spores / mL. 5 3 × 10⁻³ cells / mL 5 per mL.

[0010] Preferably, the ratio of the number of microalgae to the number of fungal spores is 20-50:1.

[0011] Preferably, the ratio of the number of microalgae to the number of fungal spores is 40:1.

[0012] Preferably, the inoculation concentration of the microalgae is 8 × 10⁻⁶. 7 The inoculation concentration of the fungus was 2 × 10⁶ spores / mL. 5 per mL.

[0013] Preferably, the straw includes one or more of wheat straw, corn cobs, and rice straw.

[0014] Preferably, the straw is corn cob.

[0015] Preferably, the straw hydrolysate is prepared by the following steps: drying and crushing straw to obtain straw powder, mixing the straw powder with water and sterilizing to obtain a mixture, adding cellulase and hemicellulase to the mixture, enzymatically hydrolyzing for 10-14 hours and centrifuging, and taking the supernatant to obtain the straw hydrolysate.

[0016] Preferably, the enzyme activity ratio of the cellulase and the hemicellulase is 1.5-2.5:1.

[0017] Preferably, the enzyme activity ratio of the cellulase and the hemicellulase is 2:1.

[0018] Preferably, the amount of straw hydrolysate added is 10%-50% of the volume of the livestock wastewater.

[0019] Preferably, the amount of straw hydrolysate added is 20% of the volume of the livestock wastewater.

[0020] Preferably, the parameters for the shaking co-culture are as follows: light intensity 4800-5200 lx, light-dark cycle 12h / 12h, temperature 27-29℃, shaking speed 140-160 r / min, and culture time 5-7d.

[0021] Preferably, the parameters for the shaking co-culture are as follows: light intensity 5000 lx, light-dark cycle 12h / 12h, temperature 28℃, and shaking speed 150 r / min.

[0022] In summary, this application includes at least one of the following beneficial technical effects:

[0023] 1. The present application describes a microalgae and fungi forming an algae-bacterial purification system in wastewater. The microalgae release oxygen through photosynthesis to promote the degradation of organic matter by the fungi, while absorbing nitrogen and phosphorus to synthesize their own proteins and lipids. Combined with the straw hydrolysate to provide the algae and fungi with nutrients such as sugars and amino acids, the removal rate of ammonia nitrogen and total phosphorus in wastewater is improved and converted into biomass.

[0024] 2. This application utilizes straw hydrolysate to supplement the algae and bacteria purification system with nutrients such as sugars and amino acids. Secondly, it dilutes the aquaculture wastewater, reduces the fluctuation range of nutrient content in the wastewater during the purification process, and improves the stability of the wastewater treatment efficiency of the algae and bacteria purification system. Thirdly, by producing straw hydrolysate from straw, which lacks efficient utilization pathways, it is beneficial to make efficient use of polysaccharides such as cellulose and hemicellulose, as well as nutrients such as amino acids, thereby achieving "waste treatment with waste".

[0025] 3. This application constructs an algae-bacterial purification system in aquaculture wastewater by selecting green algae and Aspergillus fungi. This microalgae-fungus combination has a synergistic effect on improving the removal rate of ammonia nitrogen and total phosphorus, as well as the total biomass yield.

[0026] 4. The purification method for aquaculture wastewater based on the synergistic effect of algae and bacteria and the resource utilization of agricultural waste is applicable to the efficient denitrification and phosphorus removal and biomass recovery of large-scale livestock and poultry breeding wastewater. Attached Figure Description

[0027] Figure 1 This is a comparison chart of the three-dimensional fluorescence determination and analysis results of the three straw hydrolysates in Examples 1, 6 and 11;

[0028] Figure 2 This is a comparison chart of the ammonia nitrogen removal rates of Examples 1-15 and Comparative Example 1;

[0029] Figure 3 This is a comparison chart of the total phosphorus removal rates of Examples 1-15 and Comparative Example 1;

[0030] Figure 4 This is a comparison chart of the total biomass yield of Examples 1-15 and Comparative Example 1;

[0031] Figure 5 This is a comparison graph showing the protein yield of Examples 1-15 and Comparative Example 1;

[0032] Figure 6 This is a comparison chart of polysaccharide yields in Examples 1-15 and Comparative Example 1;

[0033] Figure 7 Comparison diagram of microalgal photosynthetic parameters of Examples 1-15 and Comparative Example 1;

[0034] Figure 8 This is a comparison chart of ammonia nitrogen removal rates for Example 1 and Examples 16-18;

[0035] Figure 9 This is a comparison chart of the total phosphorus removal rates of Example 1 and Examples 16-18;

[0036] Figure 10 Comparison of field emission scanning electron microscope images of microalgae and fungi in the algae and fungi purification systems of Examples 1 and 16-18. Detailed Implementation

[0037] The present application will be further described in detail below with reference to embodiments and accompanying drawings. The following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the following embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the methods used are conventional methods known in the art, and the consumables and reagents used are commercially available. Unless otherwise stated, the technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be applied to the present invention.

[0038] The raw materials used in the examples and comparative examples are all commercially available.

[0039] Example 1

[0040] Embodiment 1 of this application discloses a method for purifying aquaculture wastewater, comprising the following steps:

[0041] Simulated aquaculture wastewater contained the following components: 120 mg / L ammonia nitrogen, 10 mg / L total phosphorus, 500 mg / L chemical oxygen demand (COD), 2.86 mg / L H3BO3, 1.81 mg / L MnCl2·H2O, 0.222 mg / L ZnSO2·7H2O, 0.079 mg / L CuSO4·5H2O, 0.390 mg / L Na2MoO4·2H2O, and 0.049 mg / L Co(NO3)2·6H2O.

[0042] Preparation of straw hydrolysate: Select dry straw (corn cob), sun-dry until the moisture content is less than 10%, crush it with a pulverizer and pass it through a 100-mesh sieve to obtain straw powder. Weigh 10g of straw powder and mix it with 250mL of deionized water, then transfer it to an autoclave and autoclave at 121℃ for 30min to obtain a mixture. Place the mixture in a shake flask and add cellulase and hemicellulase with an enzyme activity ratio of 2:1, with a total enzyme addition of 300U / g dry straw weight. Enzymatically hydrolyze the mixture in a shaker at 28℃ and 150r / min for 12h. Finally, centrifuge at 8000r / min for 10min and take the supernatant as the straw hydrolysate.

[0043] Algae and bacteria pre-culture: Microalgae (Chlorella sorokinense, Chlorella sorokinianaThe algae (FACHB-24) were purchased from the Freshwater Algae Culture Bank of the Institute of Hydrobiology, Chinese Academy of Sciences, and were cultured on a shaker in BG-11 medium (purchased from Qingdao Haibo Biotechnology Co., Ltd., catalog number: HB8793). The light intensity was controlled at 5000 lx, the light / dark cycle was 12 h / 12 ​​h, the temperature was 28 ± 1 ℃, and the shaker speed was 150 r / min. The fungus (Aspergillus oryzae) was then introduced. Aspergillus oryzae The spores were purchased from the China Center for Type Culture Collection (CCTCC AF 2018017) and inoculated onto potato dextrose agar plates (purchased from Qingdao Haibo Biotechnology Co., Ltd., catalog number: HB0233-4). The plates were incubated at 28±1℃ for 20-30 days. The spores were washed with sterile water containing 0.1% Tween 80 and then centrifuged to prepare a spore suspension.

[0044] Construction and cultivation of the algae-bacterial purification system: Simulated aquaculture wastewater was placed in an Erlenmeyer flask, and 20% (v / v) of straw hydrolysate was added. Spore suspension and microalgae were then inoculated, with the microalgae to spore ratio controlled at 40:1, to obtain the algae-bacterial purification system. The microalgae concentration in the algae-bacterial purification system was 8 × 10⁻⁶. 6 The spore concentration of fungi is 2 × 10⁶ / mL. 5 The number of cells / mL was determined by placing the conical flask in a light-shaking incubator with a light intensity of 5000±200 lx, a light-dark cycle of 12h / 12h, a temperature of 28±1℃, and a shaking speed of 150 r / min.

[0045] Example 2

[0046] Example 2 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 2 and Example 1 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 2 is 10%.

[0047] Example 3

[0048] Example 3 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 3 and Example 1 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 3 is 30%.

[0049] Example 4

[0050] Example 4 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 4 and Example 1 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 4 is 40%.

[0051] Example 5

[0052] Example 5 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 5 and Example 1 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 5 is 50%.

[0053] Example 6

[0054] Example 6 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 6 and Example 1 is that wheat straw is used instead of corn cob in the straw hydrolysate preparation step of Example 5.

[0055] Example 7

[0056] Example 7 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 7 and Example 6 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 7 is 10%.

[0057] Example 8

[0058] Example 8 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 8 and Example 6 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 8 is 30%.

[0059] Example 9

[0060] Example 9 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 9 and Example 6 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 9 is 40%.

[0061] Example 10

[0062] Example 10 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 10 and Example 6 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 10 is 50%.

[0063] Example 11

[0064] Example 11 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 11 and Example 1 is that rice straw is used instead of corn cob in the straw hydrolysate preparation step of Example 11.

[0065] Example 12

[0066] Example 12 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 12 and Example 11 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 12 is 10%.

[0067] Example 13

[0068] Example 13 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 13 and Example 11 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 13 is 30%.

[0069] Example 14

[0070] Example 14 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 14 and Example 11 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 9 is 40%.

[0071] Example 15

[0072] Example 15 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 15 and Example 11 is that the amount of straw hydrolysate added in the construction and cultivation steps of the algae and bacteria purification system in Example 15 is 50%.

[0073] Example 16

[0074] Example 16 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 16 and Example 1 is that Aspergillus niger is used in the pre-culture step of algae and bacteria in Example 16. Aspergillus niger (Purchased from the China Center for Type Culture Collection, accession number: CCTCC AF 2016004) to replace Aspergillus oryzae.

[0075] Example 17

[0076] Example 17 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 17 and Example 1 is that the pre-culture step of algae and bacteria in Example 17 uses Scenedesmus dimorphus (…). Chlorella sorokiniana Purchased from the Freshwater Algae Culture Bank of the Institute of Hydrobiology, Chinese Academy of Sciences (accession number: FACHB-496) to replace Chlorella sorokinosa.

[0077] Example 18

[0078] Example 18 of this application discloses a method for purifying aquaculture wastewater. The difference between Example 18 and Example 1 is that in the pre-culture step of algae and bacteria in Example 18, Scenedesmus dimorphus is used instead of Chlorella sorogenesis, and Aspergillus niger is used instead of Aspergillus oryzae.

[0079] Comparative Example 1

[0080] Comparative Example 1 discloses a method for purifying aquaculture wastewater. The difference between Comparative Example 1 and Example 1 is that no straw hydrolysate is added in the construction and cultivation steps of the algae and bacteria purification system in Comparative Example 1.

[0081] Testing and Inspection

[0082] (1) Three-dimensional fluorescence determination and analysis of the straw hydrolysates of Examples 1, 6 and 11 were performed using a fluorescence spectrometer. The results are as follows: Figure 1 As shown, the results of Example 1 are labeled as corn hydrolysate, the results of Example 6 are labeled as wheat hydrolysate, and the results of Example 11 are labeled as rice hydrolysate.

[0083] (2) After culturing the algae-bacterial purification system for 6 days, the ammonia nitrogen content in the systems of Examples 1-15 and Comparative Example 1 was determined by Nessler's reagent spectrophotometry. The ammonia nitrogen removal rate was calculated, and the comparison results of the ammonia nitrogen removal rates of Examples 1-15 and Comparative Example 1 are as follows: Figure 2 As shown in the figure, Comparative Example 1 is labeled as water, Examples 1-5 are labeled as corn hydrolysate, Examples 6-10 are labeled as wheat hydrolysate, and Examples 11-15 are labeled as rice straw hydrolysate. The total phosphorus content in the systems of Examples 1-15 and Comparative Example 1 was determined by the molybdenum antimony spectrophotometric method, and the total phosphorus removal rate was calculated. The comparison results of the total phosphorus removal rates of Examples 1-15 and Comparative Example 1 are shown below. Figure 3 As shown in the figure, Comparative Example 1 is labeled as water, Examples 1-5 are labeled as corn hydrolysate, Examples 6-10 are labeled as wheat hydrolysate, and Examples 11-15 are labeled as rice straw hydrolysate.

[0084] (3) After the algae-bacteria purification system was cultured for 6 days, the total biomass yield in the systems of Examples 1-15 and Comparative Example 1 was determined by the dry weight method. The results were compared with those of Example 1. Figure 4 As shown, the protein yield in the systems of Examples 1-15 and Comparative Example 1 was detected using the Coomassie Brilliant Blue assay. The results were compared with those of Comparative Example 1. Figure 5 As shown; the polysaccharide yield in the systems of Examples 1-15 and Comparative Example 1 was determined using the phenol-sulfuric acid method. The results were compared with those of Example 1. Figure 6 As shown.

[0085] (4) After culturing the algae-bacterial purification system for 6 days, the photosynthetic parameters of microalgae in the systems of Examples 1-15 and Comparative Example 1 were detected using a chlorophyll fluorescence spectrometer. Fv / Fm ), the result is for example Figure 7 As shown.

[0086] (5) After culturing the algae-bacterial purification system for 6 days, the ammonia nitrogen content in the systems of Example 1 and Examples 16-18 was determined by Nessler's reagent spectrophotometry. The ammonia nitrogen removal rate was calculated, and the comparison results of the ammonia nitrogen removal rates of Example 1 and Examples 16-18 are as follows: Figure 8As shown in the figure, Example 1 is labeled as *Chlorella vulgaris* + *Aspergillus oryzae*, Example 16 is labeled as *Chlorella vulgaris* + *Aspergillus niger*, Example 17 is labeled as *Scenedesmus asiatica* + *Aspergillus oryzae*, and Example 18 is labeled as *Scenedesmus asiatica* + *Aspergillus niger*. The total phosphorus content in the systems of Examples 1 and Examples 16-18 was determined by the molybdenum antimony spectrophotometric method, and the total phosphorus removal rate was calculated. The comparison results of the total phosphorus removal rates of Examples 1 and Examples 16-18 are shown below. Figure 9 As shown in the figure, Example 1 is labeled as Chlorella + Aspergillus oryzae, Example 16 is labeled as Chlorella + Aspergillus niger, Example 17 is labeled as Scenedesmus + Aspergillus oryzae, and Example 18 is labeled as Scenedesmus + Aspergillus niger.

[0087] (6) After culturing the algae and bacteria purification system for 6 days, scanning electron microscopy was used to image the algae and bacteria in the systems of Example 1 and Examples 16-18. The results are as follows: Figure 10 As shown, the results of Example 1 are as follows: Figure 10 As shown in (a), the results of Example 16 are as follows: Figure 10 As shown in (b), the results of Example 17 are as follows: Figure 10 As shown in (c), the results of Example 18 are as follows Figure 10 As shown in (d).

[0088] Results Analysis

[0089] Reference Figure 1 It can be seen that the three straw hydrolysates in Examples 1, 6 and 11 have certain similarities in organic composition, all containing protein-like substances, humic substances and soluble microbial metabolites. The straw hydrolysate in Example 1 has higher contents of fulvic acid, humic acid-like substances and soluble microbial metabolites than the straw hydrolysates in Examples 6 and 11.

[0090] Reference Figures 2-7 , Figures 2-6 This study demonstrates the impact of straw type and hydrolysate addition ratio on ammonia nitrogen removal rate, total phosphorus removal rate, total biomass yield, protein yield, and polysaccharide yield in an algae-bacterial purification system. It shows that a 20% addition of straw hydrolysate results in the highest ammonia nitrogen removal rate, total phosphorus removal rate, and protein yield. In particular, using corn cobs as straw, the resulting hydrolysate shows significantly better results than hydrolysates made from wheat straw and rice straw in improving ammonia nitrogen removal rate, total phosphorus removal rate, total biomass yield, protein yield, and polysaccharide yield. Figure 1 The results indicate that using corn cobs as straw allows the fulvic acid, humic acid, and soluble microbial metabolites in the resulting straw hydrolysate to provide a suitable growth environment and sufficient nutrients for the microalgae-fungus system, thereby improving its efficiency in treating livestock and poultry wastewater. (Reference) Figure 7When using corn cobs to make straw hydrolysate, it has significant advantages in promoting microalgae photosynthesis in algae purification systems, especially when the addition ratio is 10%-30%, which can improve photosynthetic efficiency and avoid the inhibitory effect caused by high concentration.

[0091] Reference Figure 8-10 , Figure 8-9 This study demonstrates the impact of microalgae and fungi species in an algae-bacterial system on the ammonia nitrogen and total phosphorus removal rates of the purification system. Specifically, the algae-bacterial system composed of *Chlorella sorokinense* and *Aspergillus oryzae* in Example 1 showed a greater advantage in improving the ammonia nitrogen and total phosphorus removal rates compared to other algae-bacterial systems. (Refer to...) Figure 10 ,Depend on Figure 10 (a) It can be seen that *Chlorella sorokinense* is round or elliptical and relatively evenly distributed, while *Aspergillus oryzae* hyphae exhibit a well-developed branching structure with a relatively smooth surface. The hyphae of *Chlorella sorokinense* and *Aspergillus oryzae* intertwine, with *Chlorella sorokinense* cells attached to or scattered among the hyphae, resulting in a relatively loose overall structure, which is conducive to material exchange and nutrient transfer; (Refer to...) Figure 10 (b) When *Chlorella sorokinense* was co-cultured with *Aspergillus niger*, the *Aspergillus niger* hyphae were thicker, had fewer branches, and had a relatively rough surface. The *Chlorella sorokinense* cells did not bind as tightly to *Aspergillus niger* hyphae as they did to *Aspergillus oryzae* hyphae. (Refer to...) Figure 10 (c) and Figure 10 (d) It is evident that *Scenedesmus dimorphus* cells are spindle-shaped or oblong, resulting in relatively small contact areas with *Aspergillus oryzae* and *Aspergillus niger* hyphae, leading to reduced material transfer efficiency. Furthermore, the shape and arrangement of *Scenedesmus dimorphus* cells result in a more compact overall structure, with relatively small gaps between cells and hyphae, which is detrimental to material exchange and nutrient transfer. In conclusion, the algae-bacterial system composed of *Chlorella sorokinense* and *Aspergillus oryzae* is structurally more conducive to material exchange and nutrient transfer compared to other algae-bacterial systems, thus improving the ammonia nitrogen removal rate and total phosphorus removal rate of the algae-bacterial purification system.

[0092] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," "third," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar terms mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects. "Above," "below," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0093] The above are all optional embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for purifying aquaculture wastewater, characterized in that: Includes the following steps: Straw is enzymatically hydrolyzed to obtain straw hydrolysate. The straw hydrolysate, microalgae, and fungal spores are added to aquaculture wastewater and co-cultured under shaking. The microalgae include green algae, and the fungi include Aspergillus.

2. The method for purifying aquaculture wastewater according to claim 1, characterized in that: The microalgae include one or both of Chlorella sorokinensis and Scenedesmus.

3. The method for purifying aquaculture wastewater according to claim 1, characterized in that: The fungi include one or both of Aspergillus oryzae and Aspergillus niger.

4. The method for purifying aquaculture wastewater according to claim 1, characterized in that: The inoculation concentration of the microalgae was 1×10⁻⁶. 6 Cells / mL - 1×10 7 The inoculation concentration of the fungus is 1 × 10⁶ spores / mL. 5 3 × 10⁻³ cells / mL 5 per mL.

5. The method for purifying aquaculture wastewater according to claim 4, characterized in that: The ratio of the number of microalgae to the number of fungal spores is 20-50:

1.

6. The method for purifying aquaculture wastewater according to claim 1, characterized in that: The straw includes one or more of wheat straw, corn cobs, and rice straw.

7. The method for purifying aquaculture wastewater according to claim 1, characterized in that: The straw hydrolysate is prepared by the following steps: drying straw and crushing it to obtain straw powder, mixing the straw powder with water and sterilizing it to obtain a mixture, adding cellulase and hemicellulase to the mixture, enzymatically hydrolyzing for 10-14 hours and centrifuging, and taking the supernatant to obtain the straw hydrolysate.

8. The method for purifying aquaculture wastewater according to claim 7, characterized in that: The enzyme activity ratio of the cellulase and the hemicellulase is 1.5-2.5:

1.

9. The method for purifying aquaculture wastewater according to claim 1, characterized in that: The amount of straw hydrolysate added is 10%-50% of the volume of the livestock wastewater.

10. The method for purifying aquaculture wastewater according to claim 1, characterized in that: The parameters for the shaking co-culture are as follows: light intensity 4800-5200 lx, light-dark cycle 12h / 12h, temperature 27-29℃, and shaking speed 140-160 r / min.

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