Method for two-stage synergistic purification of aquaculture tail water by microalgae and photosynthetic bacteria

Abstract

The invention provides a method for two-stage synergistic purification of aquaculture tail water by microalgae and photosynthetic bacteria, and the method comprises the following steps: mixing aquaculture tail water with microalgae, introducing carbon dioxide, carrying out first-stage treatment and solid-liquid separation under an illumination condition, collecting liquid, mixing with photosynthetic bacteria, carrying out second-stage treatment, and carrying out solid-liquid separation, purified tail water is obtained. According to the method, the microalgae and the photosynthetic bacteria take pollutants of the aquaculture tail water as nutrient elements required by growth, two-stage treatment is carried out, the aquaculture tail water is synergistically purified, and the total nitrogen content is reduced to an extremely low level on the premise of ensuring that the total phosphorus content, the permanganate index, the suspended matter content and the pH value reach the standard.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture wastewater treatment technology, specifically relating to a two-stage synergistic purification method of aquaculture wastewater using microalgae and photosynthetic bacteria. Background Technology

[0002] With the large-scale development of aquaculture in my country, pollution from aquaculture wastewater has become a key source of eutrophication. According to the "Second National Pollution Source Census Bulletin," agricultural pollutant emissions account for 47% of the total water pollution nationwide. Among these, the total nitrogen, total phosphorus, and permanganate index in freshwater aquaculture wastewater far exceed the natural water body's remediation capacity. However, traditional physicochemical methods have significant drawbacks. Physical methods struggle to treat soluble organic matter and ions in water, while chemical methods, though effective, generate severe secondary pollution and increase economic investment. Essentially, traditional physicochemical methods waste limited resources, fail to achieve pollution recycling, and contradict the concept of sustainable development.

[0003] CN114409095A discloses a method for treating aquaculture wastewater using immobilized photosynthetic bacterial communities. The method includes: using pellets immobilized with photosynthetic bacterial communities to treat the wastewater, wherein the pellets are carried by a chitosan-sodium alginate complex, and the carrier contains Rhodopseudomonas, Desulfovibrio, protein bacteria, and Bacteroides. CN118063000A discloses a method for remediating aquaculture wastewater using photosynthetic bacteria, including: inoculating a microalgae-microorganism symbiosis onto an immobilized nanoparticle carrier; introducing the wastewater into a bioreactor for long-term acclimatization; planting aquatic plants in the bioreactor; inoculating activated sludge into the bioreactor; operating the bioreactor; monitoring the water quality parameters at the outlet; and adjusting the bioreactor parameters.

[0004] Existing biological treatment methods achieve controlled treatment of microbial communities by introducing additional encapsulation materials and nanoparticle carriers. However, these methods are complex, and the extra materials increase the risk of secondary water pollution and raise economic costs. Furthermore, the co-treatment of aquaculture wastewater by algae and bacteria still has shortcomings; the treatment effect is unstable, making it difficult to promote large-scale treatment in production practice. Therefore, there is an urgent need to develop a simple, convenient, and highly efficient method for co-treating aquaculture wastewater by algae and bacteria. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a two-stage synergistic purification method for aquaculture wastewater using microalgae and photosynthetic bacteria. This method ensures that the total phosphorus content, permanganate index, suspended solids content, and pH value of the wastewater meet the standards, while reducing the total nitrogen content to an extremely low level, ultimately complying with the "DB44 / 2462-2024 Freshwater Aquaculture Wastewater Discharge Standard".

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for the two-stage synergistic purification of aquaculture wastewater using microalgae and photosynthetic bacteria, the method comprising:

[0008] The aquaculture wastewater and microalgae are mixed, carbon dioxide is introduced, and the first stage of treatment is carried out under light conditions. Solid-liquid separation is performed, the liquid is collected and mixed with photosynthetic bacteria, and then the second stage of treatment is carried out. Solid-liquid separation is performed to obtain purified wastewater.

[0009] In this invention, microalgae and photosynthetic bacteria use pollutants from aquaculture wastewater as nutrients for growth and carry out two-stage treatment to synergistically purify the aquaculture wastewater. Under the premise of ensuring that the total phosphorus content, permanganate index, suspended solids content and pH value meet the standards, the total nitrogen content is reduced to an extremely low level.

[0010] In traditional algae-bacteria co-treatment, the rapid absorption of phosphorus by photosynthetic bacteria limits phosphorus absorption during microalgae metabolism, thus affecting their absorption of nitrogen and reducing pollutants. This invention, however, first controls the content of various substances in the water through microalgae, providing suitable metabolic conditions for photosynthetic bacteria. The two complement each other, synergistically purifying aquaculture wastewater in a two-stage process, ultimately meeting the "DB44 / 2462-2024 Freshwater Aquaculture Wastewater Discharge Standard".

[0011] Preferably, the microalgae include any one or a combination of at least two of Scenedesmus, Chlorella ellipsoides, or Chlorella kJ.

[0012] Preferably, the total amount of microalgae used is (0.01-0.1) g / L.

[0013] The specific point values ​​in (0.01-0.1) can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, etc.

[0014] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0015] Preferably, the microalgae include Scenedesmus, Chlorella ellipsoides, and Chlorella kJ.

[0016] This invention preferably uses a combination of Scenedesmus, Chlorella ellipsoides, and Chlorella kappa for two-stage synergistic purification of aquaculture wastewater. The above three microalgae have a synergistic effect. By controlling the content of nutrients required by photosynthetic bacteria before and during treatment, the purification effect of the wastewater treated by the co-treatment of algae and bacteria is maximized.

[0017] Preferably, the ratio of the amounts of Scenedesmus, Chlorella ellipsoides and Chlorella kappa is (1-3):(2-4):(4-6).

[0018] The specific point values ​​in (1-3) can be 1, 1.1, 1.2, 1.5, 1.7, 2, 2.3, 2.5, 2.8 or 3, etc.

[0019] The specific point values ​​in (2-4) can be 2, 2.1, 2.2, 2.5, 2.7, 3, 3.3, 3.5, 3.8 or 4, etc.

[0020] The specific point values ​​in (4-6) can be 4, 4.1, 4.2, 4.5, 4.7, 5, 5.3, 5.5, 5.8 or 6, etc.

[0021] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0022] Preferably, the photosynthetic bacteria include any one or a combination of at least two of Rhodopseudomonas palustris, Microcystis thiophile, or Rhodopseudomonas capsulatum.

[0023] Preferably, the total viable count of the photosynthetic bacteria is (1-5)×10⁻⁶. 6 CFU / mL.

[0024] The specific point values ​​in (1-5) can be 1, 1.1, 1.2, 1.5, 1.7, 2, 2.3, 2.5, 2.8, 3, 3.5, 4, 4.5 or 5, etc.

[0025] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0026] Preferably, the photosynthetic bacteria include Rhodopseudomonas palustris, Rhodopseudomonas thiophilus, and Rhodopseudomonas capsulatum.

[0027] This invention preferably uses a combination of Rhodopseudomonas palustris, Rhodopseudomonas thiophilus, and Rhodopseudomonas capsulatum for two-stage synergistic purification of aquaculture wastewater. The above three photosynthetic bacteria have a synergistic effect, reducing the competition for phosphorus by algae and bacteria during the wastewater purification process. While the photosynthetic bacteria efficiently purify the wastewater, they also maintain the metabolic process of microalgae, thus maximizing the purification effect of the co-treatment of algae and bacteria.

[0028] Preferably, the ratio of viable counts of *Rhodopseudomonas palustris*, *Microcystis thiophile*, and *Rhodopseudomonas capsulatum* is (1-3):(2-4):(4-6).

[0029] The specific point values ​​in (1-3) can be 1, 1.1, 1.2, 1.5, 1.7, 2, 2.3, 2.5, 2.8 or 3, etc.

[0030] The specific point values ​​in (2-4) can be 2, 2.1, 2.2, 2.5, 2.7, 3, 3.3, 3.5, 3.8 or 4, etc.

[0031] The specific point values ​​in (4-6) can be 4, 4.1, 4.2, 4.5, 4.7, 5, 5.3, 5.5, 5.8 or 6, etc.

[0032] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0033] Preferably, the processing time for the first stage is 80-110 hours, for example, 80 hours, 81 hours, 82 hours, 85 hours, 87 hours, 90 hours, 93 hours, 95 hours, 98 hours, 100 hours, 105 hours, or 110 hours.

[0034] Preferably, the processing time for the first stage is 90-102 hours, for example, it can be 90 hours, 91 hours, 92 hours, 93 hours, 94 hours, 95 hours, 96 hours, 97 hours, 98 hours, 99 hours, 100 hours, 101 hours, or 102 hours.

[0035] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0036] In this invention, the time for the first stage of treatment is preferably within the above-mentioned range, and the two-stage synergistic purification of aquaculture wastewater by microalgae and photosynthetic bacteria is more effective.

[0037] Preferably, the processing time for the second stage is 60-85 hours, for example, 60 hours, 61 hours, 62 hours, 65 hours, 67 hours, 80 hours, 81 hours, 82 hours, 83 hours, 84 hours, or 85 hours.

[0038] Preferably, the processing time for the second stage is 66-78 hours, for example, 66 hours, 67 hours, 68 hours, 69 hours, 70 hours, 71 hours, 72 hours, 73 hours, 74 hours, 75 hours, 76 hours, 77 hours, or 78 hours.

[0039] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0040] In this invention, the time for the second stage of treatment is preferably within the above-mentioned range, and the two-stage synergistic purification of aquaculture wastewater by microalgae and photosynthetic bacteria is more effective.

[0041] Preferably, the volume percentage of carbon dioxide in the total gas system is 10-20%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc.

[0042] Preferably, the flow rate of the carbon dioxide is 200-400 mL / min, for example, it can be 200 mL / min, 210 mL / min, 220 mL / min, 250 mL / min, 270 mL / min, 300 mL / min, 330 mL / min, 350 mL / min, 380 mL / min or 400 mL / min, etc.

[0043] Preferably, the intensity of the light is 6000-10000 lux, for example, it can be 6000 lux, 6100 lux, 6200 lux, 6500 lux, 6700 lux, 7000 lux, 7300 lux, 7500 lux, 7800 lux, 8000 lux, 9000 lux, or 10000 lux, etc.

[0044] Other specific point values ​​within the range of the above values ​​can be selected, and will not be elaborated on here.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] In this invention, microalgae and photosynthetic bacteria use pollutants from aquaculture wastewater as nutrients for growth and carry out two-stage treatment to synergistically purify the aquaculture wastewater. Under the premise of ensuring that the total phosphorus content, permanganate index, suspended solids content and pH value meet the standards, the total nitrogen content is reduced to an extremely low level. Detailed Implementation

[0047] To further illustrate the technical means and effects of the present invention, the following describes the technical solution of the present invention in conjunction with preferred embodiments of the present invention. However, the present invention is not limited to the scope of the embodiments.

[0048] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0049] The sources of materials used in the following specific embodiments are as follows:

[0050] Rhodopseudomonas palustris was obtained from the American Type Culture Collection (ATCC 17001), Rhodopseudomonas thiophile was obtained from the Shanghai Biotechnology Collection Center (SHMCC D51943), and Rhodopseudomonas capsulatum was obtained from the American Type Culture Collection (ATCC 11166).

[0051] Example 1

[0052] This embodiment provides a method for purifying aquaculture wastewater, the method comprising:

[0053] (1) 300 L of aquaculture wastewater was extracted into a horizontal tube photobioreactor, and Scenedesmus, Chlorella vulgaris and Chlorella kappa were added. Their initial concentrations in the treatment system were 0.006 g / L, 0.012 g / L and 0.036 g / L, respectively. Then, carbon dioxide accounting for 15% of the total gas volume was introduced and the flow rate was set to 300 mL / min. The treatment was carried out for 96 h under a light intensity of 8000 lux, filtered, and the filtered water was collected.

[0054] (2) Rhodopseudomonas palustris, sulfo-loving red oomycetes, and capsular red bacteria were introduced into the filtered water from step (1), with initial viable counts of 0.6 × 10⁻⁶ for each species. 6 CFU / mL, 0.9×10 6 CFU / mL and 1.5×10 6 CFU / mL, treated for 72 h, filtered, to obtain purified effluent.

[0055] Example 2

[0056] This embodiment provides a method for purifying aquaculture wastewater, the method comprising:

[0057] (1) 300 L of aquaculture wastewater was extracted into a horizontal tube photobioreactor, and Scenedesmus, Chlorella vulgaris and Chlorella kappa were added. Their initial concentrations in the treatment system were 0.02 g / L, 0.03 g / L and 0.05 g / L, respectively. Then, carbon dioxide accounting for 10% of the total gas volume was introduced and the flow rate was set to 400 mL / min. The treatment was carried out for 102 h under a light intensity of 10000 lux, filtered, and the filtered water was collected.

[0058] (2) Rhodopseudomonas palustris, sulfo-loving red oomycetes, and capsular red bacteria were introduced into the filtered water from step (1), with initial viable counts of 0.6 × 10⁻⁶ for each species. 6 CFU / mL, 0.8×10 6 CFU / mL and 0.8×106 CFU / mL, treated for 66 h, filtered, to obtain purified effluent.

[0059] Example 3

[0060] This embodiment provides a method for purifying aquaculture wastewater, the method comprising:

[0061] (1) 300 L of aquaculture wastewater was drawn into a horizontal tube photobioreactor, and Scenedesmus, Chlorella vulgaris and Chlorella kappa were added. Their initial concentrations in the treatment system were 0.015 g / L, 0.02 g / L and 0.02 g / L, respectively. Then, carbon dioxide accounting for 20% of the total gas volume was introduced and the flow rate was set to 200 mL / min. The treatment was carried out for 90 h under a light intensity of 6000 lux, filtered, and the filtered water was collected.

[0062] (2) Rhodopseudomonas palustris, sulfo-loving red oomycetes, and capsular red bacteria were introduced into the filtered water from step (1), with initial viable counts of 0.2 × 10⁻⁶ for each species. 6 CFU / mL, 0.4×10 6 CFU / mL and 1.2×10 6 CFU / mL, treated for 78 h, filtered, to obtain purified effluent.

[0063] Example 4

[0064] This embodiment provides a method for purifying aquaculture wastewater, the method comprising:

[0065] (1) 300 L of aquaculture wastewater was drawn into a horizontal tube photobioreactor and Scenedesmus, Chlorella vulgaris and Chlorella kappa were added. Their initial concentrations in the treatment system were 0.006 g / L, 0.012 g / L and 0.036 g / L, respectively. Then, carbon dioxide accounting for 15% of the total gas volume was introduced and the flow rate was set to 300 mL / min. The treatment was carried out for 80 h under a light intensity of 8000 lux. The water was then filtered and collected.

[0066] (2) Rhodopseudomonas palustris, sulfo-loving red oomycetes, and capsular red bacteria were introduced into the filtered water from step (1), with initial viable counts of 0.6 × 10⁻⁶ for each species. 6 CFU / mL, 0.9×10 6 CFU / mL and 1.5×10 6 CFU / mL, treated for 85 h, filtered to obtain purified effluent.

[0067] Example 5

[0068] This embodiment provides a method for purifying aquaculture wastewater, the method comprising:

[0069] (1) 300 L of aquaculture wastewater was extracted into a horizontal tube photobioreactor, and Scenedesmus, Chlorella vulgaris and Chlorella kappa were added. Their initial concentrations in the treatment system were 0.006 g / L, 0.012 g / L and 0.036 g / L, respectively. Then, carbon dioxide accounting for 15% of the total gas volume was introduced and the flow rate was set to 300 mL / min. The treatment was carried out for 110 h under a light intensity of 8000 lux, filtered, and the filtered water was collected.

[0070] (2) Rhodopseudomonas palustris, sulfo-loving red oomycetes, and capsular red bacteria were introduced into the filtered water from step (1), with initial viable counts of 0.6 × 10⁻⁶ for each species. 6 CFU / mL, 0.9×10 6 CFU / mL and 1.5×10 6 CFU / mL, treated for 60 h, filtered to obtain purified effluent.

[0071] Example 6

[0072] This embodiment provides a method for purifying aquaculture wastewater. The only difference between this embodiment and Embodiment 1 is that in step (1), no Scenedesmus is added, and the reduced amount is proportionally allocated to Chlorella vulgaris and Chlorella kappa. All other steps remain unchanged.

[0073] Example 7

[0074] This embodiment provides a method for purifying aquaculture wastewater. The only difference between this embodiment and Embodiment 1 is that in step (1), no Chlorella ovalis is added, and the reduced amount is proportionally allocated to Scenedesmus and Chlorella kJ. All other steps remain unchanged.

[0075] Example 8

[0076] This embodiment provides a method for purifying aquaculture wastewater. The only difference between this embodiment and Embodiment 1 is that Chlorella kappa is not added in step (1), and the reduced amount is proportionally allocated to Scenedesmus and Chlorella ellipsoides. All other steps remain unchanged.

[0077] Example 9

[0078] This embodiment provides a method for purifying aquaculture wastewater. The only difference between this embodiment and Embodiment 1 is that in step (2), Rhodopseudomonas palustris is not added. Instead, the reduced number of live bacteria is proportionally distributed to Rhodopseudomonas sulfophilus and Rhodopseudomonas capsulatum. All other steps remain unchanged.

[0079] Example 10

[0080] This embodiment provides a method for purifying aquaculture wastewater. The only difference between this embodiment and Embodiment 1 is that in step (2), sulfur-loving red oomycetes are not added. Instead, the reduced number of live bacteria is proportionally distributed to Rhodopseudomonas palustris and Rhodopseudomonas capsulatum. All other steps remain unchanged.

[0081] Example 11

[0082] This embodiment provides a method for purifying aquaculture wastewater. The only difference between this embodiment and Embodiment 1 is that in step (2), no capsular red bacteria are added. Instead, the reduced number of viable bacteria is proportionally distributed to Rhodopseudomonas palustris and Rhodopseudomonas thiophile. All other steps remain unchanged.

[0083] Comparative Example 1

[0084] This comparative example provides a method for purifying aquaculture wastewater, the method comprising:

[0085] (1) 300 L of aquaculture wastewater was drawn into a horizontal tube photobioreactor, and Scenedesmus, Chlorella vulgaris, and Chlorella kappa were added. Their initial concentrations in the treatment system were 0.006 g / L, 0.012 g / L, and 0.036 g / L, respectively. Then, Rhodopseudomonas palustris, L. thiophile, and Rhodopseudomonas capsulatum were added. Their initial viable counts in the treatment system were 0.6 × 10⁻⁶, respectively. 6 CFU / mL, 0.9×10 6 CFU / mL and 1.5×10 6 CFU / mL; then, carbon dioxide accounting for 15% of the total gas volume was introduced, and the flow rate was set to 300 mL / min. The mixture was treated for 96 h under a light intensity of 8000 lux. The carbon dioxide supply was stopped and the light was no longer applied. The mixture was then treated for another 72 h, filtered, and purified effluent was obtained.

[0086] Comparative Example 2

[0087] This comparative example provides a method for purifying aquaculture wastewater, the method comprising:

[0088] (1) 300 L of aquaculture wastewater was drawn into a horizontal tube photobioreactor, and Rhodopseudomonas palustris, Rhodopseudomonas thiophile, and Rhodopseudomonas capsulatum were introduced. The initial viable counts of these bacteria in the treatment system were 0.6 × 10⁻⁶. 6 CFU / mL, 0.9×10 6 CFU / mL and 1.5×10 6 CFU / mL, treated for 72 h, filtered, and the filtered water was collected;

[0089] (2) Add Scenedesmus, Chlorella vulgaris and Chlorella kappa to the filtered water in step (1), with initial concentrations of 0.006 g / L, 0.012 g / L and 0.036 g / L respectively in the treatment system; then, introduce carbon dioxide accounting for 15% of the total gas volume percentage and set the flow rate to 300 mL / min, treat for 96 h under 8000 lux light intensity, filter, and obtain purified tailwater.

[0090] Test case

[0091] The purified effluent from Examples 1-11 and Comparative Examples 1-2 was tested three times for each group, and the average value was taken to ensure the accuracy of the test.

[0092] (1) Permanganate index COD mn Testing: According to the detection method of potassium permanganate in the environmental testing standard HJ / T 399-2007, take 100 mL of water sample, add 5 mL of 4.5M sulfuric acid solution and mix well, then add 10 mL of 0.01 M potassium permanganate standard solution, heat in a boiling water bath for 30 min, then add 10 mL of sodium oxalate standard solution. The solution should decolorize after shaking. Finally, titrate with potassium permanganate standard solution until the solution turns slightly red and remains so for at least 30 s. Record the volume of potassium permanganate standard solution consumed, V1 (mL). Take 100 mL of deionized water and perform the same operation steps, recording the volume of potassium permanganate standard solution consumed, V0 (mL). COD mn (mg / L)=((V1-V0)×0.01×8×1000) / 100.

[0093] (2) Total nitrogen content detection: The total nitrogen content was detected according to the potassium persulfate oxidation-spectrophotometric method in the water quality testing standard HJ 636-2012. 10 mL of the water sample was taken, and 5 mL of alkaline potassium persulfate solution was added (40 g of potassium persulfate was dissolved in 15 g of sodium hydroxide in deionized water, and the volume was adjusted to 1 L). The solution was placed in a high-temperature, high-pressure autoclave at 120℃ for 30 min. After cooling to room temperature, 1 mL of hydrochloric acid was added, and the absorbance at wavelengths A220 nm and A275 nm was measured. Total nitrogen content (mg / L) = ((A1-A0)-a) / (b×10), where A1 = absorbance of the tested water sample at A220 nm - absorbance of the tested water sample at A275 nm, A0 = absorbance of the blank water sample at A220 nm - absorbance of the blank water sample at A275 nm, and a and b are the intercept and slope of the potassium nitrate standard curve, respectively.

[0094] (3) Total phosphorus content detection: The total phosphorus content was detected according to the ammonium molybdate spectrophotometric method in the water quality testing standard GB 11893-89. 25 mL of the water sample was taken, and 4 mL of 50 g / L potassium persulfate solution was added. The sample was placed in a high-temperature, high-pressure autoclave at 120℃ for 30 min, then cooled to room temperature. 1 mL of 100 g / L ascorbic acid solution was added, mixed thoroughly, and allowed to stand for 30 s. Then, 2 mL of standard molybdate solution was added, mixed thoroughly, and allowed to develop color at room temperature for 15 min. The absorbance A1 of the solution at 700 nm was measured. 25 mL of deionized water was taken, and the same procedure was performed to measure the absorbance A0 at 700 nm. Total phosphorus content (mg / L) = ((A1-A0)-a) / b, where a and b are the intercept and slope of the phosphate standard curve, respectively.

[0095] (4) The suspended solids content and pH value were measured directly using a water quality analyzer and a pH meter, respectively.

[0096] The test results are shown in Table 1. This invention, by regulating the metabolic processes of microalgae and photosynthetic bacteria, synergistically purifies aquaculture wastewater through a two-stage treatment. While ensuring that the total phosphorus content, permanganate index, suspended solids content, and pH value meet the standards, the total nitrogen content is reduced to an extremely low level, which complies with the "DB44 / 2462-2024 Freshwater Aquaculture Wastewater Discharge Standard". This solves the problem of excessively rapid absorption of phosphorus by photosynthetic bacteria in the one-stage co-treatment of algae and bacteria, which causes phosphorus restriction during microalgae metabolism and thus affects its absorption of nitrogen and reducing pollutants.

[0097] Among them, Scenedesmus, Chlorella ellipsoides, and Chlorella kJK have a synergistic effect, indirectly regulating the content of nutrients required by photosynthetic bacteria before input and during treatment. Rhodopseudomonas palustris, Rhodopseudomonas thiophile, and Rhodopseudomonas capsulatum have a synergistic effect, reducing the competition of algae and bacteria for phosphorus during the effluent purification process. While photosynthetic bacteria efficiently purify the effluent, they maintain the metabolic process of microalgae. The two-stage treatment synergistically maximizes the effluent purification effect of algae and bacteria co-treatment.

[0098] Table 1

[0099]

[0100] This invention illustrates a two-stage synergistic purification method for aquaculture wastewater using microalgae and photosynthetic bacteria through the above embodiments. However, this invention is not limited to the above embodiments, meaning that it does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

[0101] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0102] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for two-stage purification of aquaculture tail water by microalgae and photosynthetic bacteria, characterized in that, The method comprises: Mixing aquaculture tail water and microalgae, passing carbon dioxide and performing first-stage treatment under light conditions, solid-liquid separation, collecting liquid and mixing with photosynthetic bacteria, performing second-stage treatment, solid-liquid separation, and obtaining purified tail water.

2. The method of claim 1, wherein, The microalgae include any one or a combination of at least two of Scenedesmus, Chlorella ovalis or Chlorella kessleri; Preferably, the total amount of the microalgae is (0.01-0.1) g / L.

3. The method of claim 2, wherein, The microalgae include Scenedesmus, Chlorella ovalis and Chlorella kessleri; Preferably, the amount ratio of the Scenedesmus, Chlorella ovalis and Chlorella kessleri is (1-3):(2-4):(4-6).

4. The method according to any one of claims 1 to 3, characterized in that, The photosynthetic bacteria include any one or a combination of at least two of Rhodopseudomonas palustris, Rhodovulum sulfidophilum or Rhodobacter capsulatus; Preferably, the total viable count of the photosynthetic bacteria is (1-5) x 10 6 CFU / mL.

5. The method of claim 4, wherein, The photosynthetic bacteria include Rhodopseudomonas palustris, Rhodovulum sulfidophilum and Rhodobacter capsulatus; Preferably, the live bacteria number ratio of the Rhodopseudomonas palustris, Rhodovulum sulfidophilum and Rhodobacter capsulatus is (1-3):(2-4):(4-6).

6. The method according to any one of claims 1-5, characterized in that, The first-stage treatment time is 80-110 h; Preferably, the first-stage treatment time is 90-102 h.

7. The method according to any one of claims 1 to 6, characterized in that, The second-stage treatment time is 60-85 h; Preferably, the second-stage treatment time is 66-78 h.

8. The method according to any one of claims 1-7, characterized in that, The volume percentage of the carbon dioxide in the total gas system is 10-20%.

9. The method according to any one of claims 1-8, characterized in that, The flow rate of the carbon dioxide is 200-400 mL / min.

10. The method according to any one of claims 1-9, characterized in that, The light intensity is 6000-10000 lux.

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