Biochar coupled bacteria-algae granular sludge as well as culture method and application thereof

Abstract

The invention discloses biochar coupled bacteria-algae granular sludge as well as a culture method and application thereof. According to the invention, in an optical sequencing batch reactor, activated sludge in a secondary sedimentation tank of a sewage treatment plant, chlorella and biochar are utilized for culturing to obtain biochar coupled bacteria-algae granular sludge, and pollutants such as COD, NH4 < + >-N, PO4 < 3->-P and antibiotics (such as enrofloxacin) contained in aquaculture wastewater can be efficiently removed by utilizing the biochar coupled bacteria-algae granular sludge under the condition that the salinity is 0.3%. Besides, the biochar coupled bacteria-algae granular sludge is good in stability, when the biochar coupled bacteria-algae granular sludge is used for treating antibiotic pollutants, the situation that the removal rate of the antibiotic pollutants is reduced along with the prolonging of time is avoided, pollutants such as COD, NH4 < + >-N, PO4 < 3-P > and antibiotics can be efficiently and stably removed, and the biochar coupled bacteria-algae granular sludge has good application prospects. The method has a good application prospect in aquaculture wastewater treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquaculture wastewater treatment, and in particular relates to a biochar-coupled bacteria-algae granular sludge and a cultivation method and application thereof. Background Art

[0002] Aquaculture wastewater contains a large amount of organic matter and ammonia nitrogen (NH4 + -N) and phosphorus (PO4 3- -P) and other pollutants, which are discharged into the surrounding water bodies without treatment, will cause eutrophication of the water bodies and affect the living environment of aquatic organisms. In addition, in the process of aquaculture, quinolone antibiotics (such as enrofloxacin (ENR)) or other drugs are often used to prevent and treat diseases, resulting in antibiotic residues in aquaculture wastewater, endangering ecological safety and human health. Therefore, when treating aquaculture wastewater, it is necessary not only to remove pollutants such as organic matter and ammonia nitrogen, but also to remove antibiotic residues. That is, the efficient removal of complex pollutants has become a key task for protecting the ecological environment and deepening pollution reduction and carbon reduction.

[0003] At present, the main treatment methods for aquaculture wastewater include physical, chemical and biological treatment. Among them, biological treatment methods include activated sludge method, biofilm method, algae treatment method and in-situ treatment using microbial preparations. Activated sludge method is a traditional biological treatment process for aquaculture wastewater, which can effectively remove organic matter and suspended solids in wastewater, and has the advantages of environmental friendliness and sustainability. However, the activated sludge method also has disadvantages. For example, the sludge output of activated sludge method for treating wastewater is large, which will increase the treatment cost and environmental burden. At the same time, it is time-consuming and has limited removal effect on pollutants such as nitrogen and phosphorus. Bacteria-algae granular sludge (MBGS) can effectively remove organic matter, ammonia nitrogen and phosphate in sewage, so it has received widespread attention, but there are few reports on the removal of antibiotics using bacteria-algae granular sludge. And with the extension of treatment time, the selection pressure of antibiotics will cause the metabolic activity of bacteria-algae granular sludge to decrease significantly, which will cause fluctuations and instability in antibiotic removal efficiency. In actual operation, pollutants in aquaculture wastewater are continuously input into the treatment system containing only algae granular sludge, and the system lacks a regular renewal or replacement mechanism for algae granular sludge. Therefore, the activity decay problem of algae granular sludge in long-term operation restricts its efficient and stable removal of antibiotic pollutants. Based on this, how to optimize the performance of algae granular sludge to improve its degradation efficiency of antibiotic pollutants and maintain its long-term stability has become a key scientific problem to be solved in the application of algae granular sludge technology in the field of aquaculture wastewater treatment. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned prior art, the present invention provides a biochar-coupled bacteria-algae granular sludge and a cultivation method and application thereof.

[0005] The first object of the present invention is to provide a method for culturing biochar-coupled bacterial-algal granular sludge.

[0006] The second object of the present invention is a biochar-coupled bacterial-algal granular sludge.

[0007] The third object of the present invention is to provide the application of the biochar-coupled bacterial-algal granular sludge or the system according to claim 7 in removing quinolone antibiotics in water bodies.

[0008] The fourth object of the present invention is to provide the application of the biochar-coupled bacterial-algal granular sludge in the preparation of a preparation for removing quinolone antibiotics in water bodies.

[0009] The fifth object of the present invention is to provide the application of the system in the preparation of a device for removing quinolone antibiotics in water bodies.

[0010] The above objects of the present invention are achieved by the following technical solutions:

[0011] In the present invention, in a photo-sequencing batch reactor, using the activated sludge from the secondary sedimentation tank of a sewage treatment plant, Chlorella vulgaris, and biochar, a biochar-coupled bacterial-algal granular sludge was cultured, which can efficiently remove COD, NH4 + -N, PO4 3 -P, and antibiotics (such as enrofloxacin) and other pollutants in aquaculture wastewater under high salinity (0.3%) conditions, and the removal effect of antibiotic pollutants is stable. Therefore, the present invention requests to protect the biochar-coupled bacterial-algal granular sludge, its culturing method and application.

[0012] The present invention provides a method for culturing biochar-coupled bacterial-algal granular sludge, comprising the following steps:

[0013] S1. Take the activated sludge from the secondary sedimentation tank of a sewage treatment plant into a photo-sequencing batch reactor, and acclimatize and culture it with a solution containing COD, NH4 + -N and PO4 3 -P to obtain flocculent activated sludge;

[0014] S2. In the flocculent activated sludge obtained in S1, add Chlorella vulgaris solution with an OD 680 of 1-2 in a ratio of the volume of sludge to Chlorella vulgaris solution of 3-10:1, and add biochar with a final concentration of 1-3 g / L for co-culture to obtain biochar-coupled bacterial-algal granular sludge.

[0015] Specifically, the operating program and time of the photo-sequencing batch reactor are as follows: water inlet for 9 - 11 minutes, standing for 88 - 92 minutes, aeration for 208 - 212 minutes, sedimentation for 38 - 42 minutes, and water drainage for 9 - 11 minutes; the aeration volume is controlled at 1 - 5 L / min; among them, the hydraulic retention time in S1 is 12 hours; S2 requires light, and the light intensity is 800 - 2500 lux, and the light / dark cycle is 12 hours of light / 12 hours of darkness.

[0016] Specifically, in the solution in S1, the concentration of COD is 900 - 1100 mg / L, NH4 + -N is 90 - 110 mg / L, and PO4 3 -P is 9 - 11 mg / L.

[0017] More specifically, the concentration of COD is 1000 mg / L, NH4 + -N is 100 mg / L, and PO4 3 -P is 10 mg / L.

[0018] In a specific embodiment of the present invention, the composition of the solution (per 20 L) is: 256.41 g of CH3COONa, 76.43 g of NH4Cl, 6 g of CaCl2, 5.0 g of MgSO4·7H2O, 4.98 g of KH2PO4, 4.87 g of K2HPO4, 1.0 mg of ZnSO4·7H2O, 1.2 mg of Na2Mo7O 24 ·2H2O, 1.2 mg of CoCl2·6H2O, 0.38 mg of CuSO4, 2 mg of MnCl2·4H2O, 1 mg of HBO3, 1 mg of AlCl3, 0.8 mg of NiCl2, 6 mg of FeSO4·7H2O, and the rest is water.

[0019] Specifically, the acclimation and cultivation of the flocculent activated sludge in S1 include the following steps:

[0020] S11. Pretreatment of activated sludge; the activated sludge collected from the secondary sedimentation tank of the sewage treatment plant is sieved, and after it stands, the supernatant is poured out to complete the pretreatment of the activated sludge;

[0021] S12. Place the pretreated activated sludge in the photo-sequencing batch reactor, and the operating program and time are: water inlet for 9 - 11 minutes, standing for 88 - 92 minutes, aeration for 208 - 212 minutes, sedimentation for 38 - 42 minutes, and water drainage for 9 - 11 minutes; the hydraulic retention time is 12 hours, the aeration volume is controlled at 1 - 5 L / min, and the volume exchange rate is 50%. Continuously acclimate and cultivate under the above conditions until its removal rates of COD, NH4 + -N and PO4 3The removal rate of -P remains stable and its MLVSS / MLSS also remains stable, thus obtaining the flocculent activated sludge.

[0022] Specifically, the initial concentration of the activated sludge collected from the secondary sedimentation tank of the sewage treatment plant is 10.0 ± 1.0 g / L.

[0023] Specifically, the sieving in S11 is sieving through a 100-mesh sieve three times.

[0024] Specifically, the reaction temperature in S12 is 24°C to 26°C.

[0025] More specifically, the reaction temperature is 25°C.

[0026] Specifically, in S12, continuous domestication is required for at least 30 days.

[0027] Specifically, the algal strain number of the Chlorella vulgaris in S2 is FACHB-11, which is purchased from the Freshwater Algae Culture Collection of the Chinese Academy of Sciences.

[0028] Specifically, the biochar in S2 is algal-based biochar obtained by pyrolyzing Chlorella vulgaris.

[0029] Specifically, the pyrolysis treatment is as follows: The freeze-dried powder of Chlorella vulgaris is dried and then crushed. It is heated at 600 - 800°C for 1 - 3 hours under constant temperature, anoxic and nitrogen-containing conditions. After cooling to room temperature, it is crushed, ground and sieved to obtain the algal-based biochar.

[0030] More specifically, the algal strain number of the Chlorella vulgaris is FACHB-11, realizing the secondary utilization of Chlorella vulgaris.

[0031] More specifically, the freeze-dried powder of Chlorella vulgaris is dried and then crushed with a crusher. The obtained powder is compacted and put into a crucible with a lid. Then the crucible is transferred to a muffle furnace and heated at a constant temperature (700°C) under anoxic nitrogen conditions for 2 hours. After cooling to room temperature, it is taken out, crushed, ground and sieved through a 100-mesh sieve to obtain the algal-based biochar.

[0032] In a specific embodiment of the present invention, the cultivation method of the Chlorella vulgaris liquid is as follows: The Chlorella vulgaris liquid and the BG-11 liquid medium are inoculated in sequence according to the volume ratios of 1:1, 1:5, and 1:10, and cultured under the conditions of a light intensity of 2000 lux and a temperature of 25°C.

[0033] Preferably, in S2, the flocculent activated sludge obtained in S1 and the Chlorella vulgaris liquid with an OD 680 of 1 - 2 are mixed at a volume ratio of 3 - 5:1, and biochar with a final concentration of 1 - 2 g / L is added for co-cultivation to obtain biochar-coupled bacteria-algae granular sludge.

[0034] Further preferably, in S2, the flocculent activated sludge obtained in S1 and the Chlorella vulgaris liquid with an OD680 The Chlorella vulgaris liquid with a ratio of 1 to 2 is mixed with the biochar at a volume ratio of 5:1 and co-cultured to obtain biochar-coupled bacteria-algae granular sludge.

[0035] Specifically, the cultivation in S2 is carried out in a photo-sequencing batch reactor; among them, the light intensity of the photo-sequencing batch reactor is 800 - 2500 lux, the operation program and time are as follows: water inlet for 9 - 11 minutes, standing for 88 - 92 minutes, aeration for 208 - 212 minutes, sedimentation for 38 - 42 minutes, and drainage for 9 - 11 minutes; the light / dark cycle is 12 hours of light / 12 hours of dark, the aeration rate is controlled at 1 - 5 L / min, and the volume exchange rate is 50%.

[0036] Preferably, the light intensity of the photo-sequencing batch reactor is 1800 - 2500 lux.

[0037] More preferably, the light intensity of the photo-sequencing batch reactor is 1800 lux.

[0038] During the cultivation of the bacteria-algae granular sludge, the cultivation temperature is 24 - 26 °C.

[0039] Specifically, in S2, the cultivation time after adding the Chlorella vulgaris liquid is 20 - 30 days, and the cultivation time after adding the biochar is at least 20 days.

[0040] More specifically, in S2, the cultivation time after adding the Chlorella vulgaris liquid is 20 days.

[0041] The present invention also provides a biochar-coupled bacteria-algae granular sludge, which is prepared by the above method of the present invention.

[0042] The present invention also provides a biochar-coupled bacteria-algae granular sludge system, and the system includes a photo-sequencing batch reactor and the biochar-coupled bacteria-algae granular sludge of the present invention.

[0043] Specifically, the construction method of the biochar-coupled bacteria-algae granular sludge system includes the following steps:

[0044] S1. Take the activated sludge from the secondary sedimentation tank of the sewage treatment plant and place it in a photo-sequencing batch reactor, and acclimatize and cultivate it with a solution containing COD, NH4 + -N and PO4 3 -P to obtain flocculent activated sludge; in the solution, the concentration of COD is 900 - 1100 mg / L, the concentration of NH4 + -N is 90 - 110 mg / L, and the concentration of PO4 3 -P is 9 - 11 mg / L;

[0045] S2. In the flocculent activated sludge obtained in S1, add Chlorella vulgaris liquid with an optical density (OD) of 1 - 2 according to the volume ratio of flocculent activated sludge to Chlorella vulgaris liquid of 3 - 10:1. Set the light intensity of the photo-sequencing batch reactor at 800 - 2500 lux. The operation program and time are as follows: water inlet for 9 - 11 minutes, standing for 88 - 92 minutes, aeration for 208 - 212 minutes, sedimentation for 38 - 42 minutes, and water drainage for 9 - 11 minutes; the light / dark cycle is 12 hours of light / 12 hours of dark, the aeration rate is controlled at 1 - 5 L / min, the volume exchange rate is 50%, and culture for 20 - 30 days; 680

[0046] S3. After the culture in S2 is completed, add biochar with a final concentration of 1 - 3 g / L, and co-culture for at least 20 days under the same conditions as in S2 to obtain biochar-coupled bacteria-algae granular sludge.

[0047] In a specific embodiment of the present invention, after 20 days of culture in S3, salinity acclimation was carried out on the obtained system; the salinity was gradually increased from 0.1% to 0.3%, and the salinity increased in increments of 0.1%, 0.2%, and 0.3%, and was increased to the next salinity every 7 days of acclimation.

[0048] In view of the fact that the biochar-coupled bacteria-algae granular sludge described in the present invention can effectively remove enrofloxacin (belonging to quinolone antibiotics) contained in water bodies. Therefore, the present invention also claims the application of the biochar-coupled bacteria-algae granular sludge or the biochar-coupled bacteria-algae granular sludge system in removing quinolone antibiotics from water bodies.

[0049] The present invention also claims the application of the biochar-coupled bacteria-algae granular sludge in the preparation of a preparation for removing quinolone antibiotics from water bodies.

[0050] The present invention also claims the application of the system in the preparation of a device for removing quinolone antibiotics from water bodies.

[0051] Specifically, the quinolone antibiotics include one or more of enrofloxacin, norfloxacin, ciprofloxacin, and ofloxacin.

[0052] In a specific embodiment of the present invention, the quinolone antibiotic is enrofloxacin.

[0053] The present invention has the following beneficial effects:

[0054] In the photo-sequencing batch reactor of the present invention, using the activated sludge from the secondary sedimentation tank of a sewage treatment plant, Chlorella vulgaris, and biochar, a biochar-coupled bacteria-algae granular sludge with a dense structure was cultivated. Using it, COD, NH4 + -N, and PO4 3 ​- Pollutants such as -P and antibiotics (e.g., enrofloxacin). In addition, the biochar-coupled algal-bacterial granular sludge described in the present invention has good stability. When using it to treat antibiotic pollutants, the removal rate of antibiotic pollutants will not decrease over time, which is beneficial to the efficient and stable removal of pollutants such as COD, NH4 + -N, PO4 3 -P and antibiotics, and has good application prospects in the treatment of aquaculture wastewater. Brief Description of the Drawings

[0055] Figure 1 It is a schematic structural diagram of the small-scale photo-sequencing batch reactor constructed for the present invention; in the figure, Influent is the influent system, Effluent is the effluent system, Light is the lighting system, and Aeration is the aeration system.

[0056] Figure 2 It shows the influence of different biochar dosages on the particle size of algal-bacterial granular sludge; the scale is 1 cm.

[0057] Figure 3 It shows the influence of different biochar dosages on the chlorophyll content in algal-bacterial granular sludge.

[0058] Figure 4 It shows the determination of the removal rates of carbon, nitrogen, and phosphorus in aquaculture wastewater by the algal-bacterial granular sludge system coupled with different dosages of algal-based biochar.

[0059] Figure 5 It shows the determination of the removal rate and specific removal rate of enrofloxacin in aquaculture wastewater by the algal-bacterial granular sludge system coupled with different dosages of algal-based biochar.

[0060] Figure 6 It shows the determination of the removal rates of carbon, nitrogen, and phosphorus in aquaculture wastewater by the algal liquid system, activated sludge system, algal-bacterial granular sludge system, and algal-based biochar-coupled algal-bacterial granular sludge system.

[0061] Figure 7 It shows the analysis of the removal effect of enrofloxacin in aquaculture wastewater by the biochar system, algal liquid system, algal-based biochar system, activated sludge system, algal-bacterial granular sludge system, and algal-based biochar-coupled algal-bacterial granular sludge system.

[0062] Different letters in the figure indicate significant differences, p < 0.05. Detailed Embodiments

[0063] The present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0064] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0065] To facilitate the cultivation of algal-bacterial granular sludge under laboratory conditions, the present invention constructs a small-scale photo-sequencing batch reactor, which includes a reactor, a lighting system, an aeration system, a timing system, and an influent and effluent system (including a peristaltic pump). The structural schematic diagram is as Figure 1 shown (the timing system is not shown in the figure); wherein, the reactor is made of transparent PVC material, with a height of 60 cm, an inner diameter of 7 cm, and an effective volume of 2 L. One operating cycle of the photo-sequencing batch reactor is divided into 5 stages, namely influent, static, aeration, sedimentation, and drainage, and the light / dark cycle is 12 hours of light / 12 hours of darkness.

[0066] Example 1 Cultivation of Algal-Bacterial Granular Sludge

[0067] The algal-bacterial granular sludge in this example is obtained by mixing the culture solution of Chlorella sp. with the flocculent activated sludge obtained after acclimation culture, and then culturing with simulated wastewater in a photo-sequencing batch reactor. The Chlorella sp. is purchased from the Freshwater Algae Culture Collection of the Chinese Academy of Sciences, and the algal strain number is FACHB-11. The activated sludge is the activated sludge from the secondary sedimentation tank of a sewage treatment plant. The composition of the simulated wastewater (per 20 L) is as follows:

[0068] 256.41 g CH3COONa, 76.43 g NH4Cl, 6 g CaCl2, 5.0 g MgSO4·7H2O, 4.98 g KH2PO4, 4.87 g K2HPO4, 1.0 mg ZnSO4·7H2O, 1.2 mg Na2Mo7O 24 ·2H2O, 1.2 mg CoCl2·6H2O, 0.38 mg CuSO4, 2 mg MnCl2·4H2O, 1 mg HBO3, 1 mg AlCl3, 0.8 mg NiCl2, 6 mg FeSO4·7H2O, and the rest is water.

[0069] 1. Enrichment culture of Chlorella sp.

[0070] The purchased Chlorella sp. liquid and BG-11 liquid medium are inoculated in sequence at a volume ratio of 1:1, 1:5, and 1:10, and cultured under the conditions of a light intensity of 2000 lux and a temperature of 25 °C. The bottle is manually shaken 3-4 times a day to prevent sticking to the wall. When the OD 680 reaches 1.5, the Chlorella sp. liquid is collected. After cultivation, the volume of the homogeneous Chlorella sp. liquid obtained is about 2 L.

[0071] 2. Acclimation culture of activated sludge

[0072] The initial concentration of the activated sludge collected from the secondary sedimentation tank in this example is 10.0 ± 1.0 g / L, and it is pretreated and then acclimated and cultured.

[0073] The pretreatment method of the activated sludge is as follows: Pass the activated sludge collected from the secondary sedimentation tank through a 100-mesh sieve three times. After it stands still, pour out the supernatant to complete the pretreatment of the activated sludge. The method of its acclimation and culture is as follows: Place the pretreated activated sludge in a photo-sequencing batch reactor. Under the condition of 25 °C, set the influent (the simulated wastewater) for 10 minutes, stand still for 90 minutes, aerate for 210 minutes, precipitate for 40 minutes, drain for 10 minutes, the hydraulic retention time is 12 hours, the aeration volume is controlled at 1 - 5 L / min, and the volume exchange rate is 50%. Continuously acclimate and culture under the above conditions for more than 30 days until its removal rates of COD, NH4 + -N and PO4 3 -P are stable and its MLVSS / MLSS is also stable, obtaining flocculent activated sludge.

[0074] 3. Optimization of the culture conditions of the bacteria-algae granular sludge

[0075] First, set the operation program and time of the photo-sequencing batch reactor, set the influent (the simulated wastewater) for 10 minutes, stand still for 90 minutes, aerate for 210 minutes, precipitate for 40 minutes, drain for 10 minutes; the light / dark cycle is 12 hours of light / 12 hours of dark, the aeration volume is controlled at 1 - 5 L / min, and the light intensity is 4000 lux. Under this condition, mix the flocculent activated sludge obtained from acclimation and culture (the sludge concentration is 4.5 ± 1.0 g / L) and the enriched Chlorella vulgaris liquid (OD 680 is 1.5) at volume ratios of 3:1, 5:1, and 10:1 respectively, and run in the photo-sequencing batch reactor for 30 days to obtain bacteria-algae granular sludge, and monitor its removal efficiency of carbon, nitrogen, and phosphorus and the average particle size of the particles and other indicators every day.

[0076] Table 1 Influence of the bacteria-algae inoculation ratio on the removal efficiency of carbon, nitrogen, and phosphorus and the average particle size of the particles

[0077]

[0078] As can be seen from the results shown in Table 1, the optimal bacteria-algae inoculation ratio is 5:1.

[0079] Keep the operation program and time of the photo-sequencing batch reactor unchanged, and mix the flocculent activated sludge obtained from acclimation and culture (the sludge concentration is 4.5 ± 1.0 g / L) and the enriched Chlorella vulgaris liquid (OD 680Mix them in a volume ratio of 5:1, and set the light intensity (the light intensity is achieved by changing the number of LED light strips) to 2500 lux, 1800 lux, and 800 lux respectively. Run in a photo-sequencing batch reactor for 30 days to obtain algal-bacterial granular sludge, and monitor the removal efficiency of carbon, nitrogen, phosphorus, and the average particle size of the particles and other indicators every day.

[0080] Table 2 Effects of light intensity on the removal efficiency of carbon, nitrogen, phosphorus and the average particle size of particles

[0081]

[0082] It can be seen from the results shown in Table 2 that the optimal light intensity is 1800 lux.

[0083] After optimization, the present invention obtains the optimal conditions for culturing the algal-bacterial granular sludge. On this basis, run the photo-sequencing batch reactor for 20 days according to the optimized conditions and observe that the algal-bacterial granular sludge culture system can be stabilized after 20 days of cultivation. The particle size of the algal-bacterial granular sludge is about 1.5 mm, and the removal rates of COD, NH4 + -N and PO4 3- -P are 79.9±4.0%, 71.9±9.9%, and 62.8±7.0%.

[0084] Finally, using the algal-bacterial granular sludge obtained by running in a photo-sequencing batch reactor for 20 days with an algal-bacterial inoculation ratio of 5:1 and a light intensity of 1800 lux for the subsequent cultivation of algal-based biochar coupled with algal-bacterial granular sludge.

[0085] Example 2 Cultivation of algal-based biochar coupled with algal-bacterial granular sludge

[0086] 1. Preparation of algal-based biochar

[0087] Place the freeze-dried powder of Chlorella powder (FACHB-11) in an 80 °C oven, dry the moisture, then crush it with a pulverizer. The obtained powder is compacted and put into a crucible with a lid, and then the crucible is transferred to a muffle furnace and heated under anoxic nitrogen conditions at a constant temperature (700 °C) for 2 hours. After cooling to room temperature, take it out, crush and grind it with a pulverizer and pass through a 100-mesh sieve to obtain Chlorella biochar (the algal-based biochar), which is put into a white transparent wide-mouth bottle for standby.

[0088] 2. Optimization of the cultivation conditions of algal-based biochar coupled with algal-bacterial granular sludge

[0089] 2 g, 4 g, 6 g, and 0 g of the algal-based biochar prepared were respectively added to 4 photo-bioreactors of bacteria and algae, i.e., the biochar dosage was set to 1 g / L, 2 g / L, 3 g / L, and 0 g / L (named 1#, 2#, 3#, and 4#). The flocculent activated sludge (sludge concentration was 4.5 ± 1.0 g / L) and the Chlorella vulgaris liquid (OD 680 was 1.5) in the photo-bioreactor had a volume ratio of 5:1. The light intensity was 1800 lux (obtained from the previous cultivation). The operation procedure and time of the photo-batch reactor were as follows: 10 minutes for influent (the simulated wastewater), 90 minutes for static settlement, 210 minutes for aeration, 40 minutes for sedimentation, and 10 minutes for drainage; the light / dark cycle was 12 hours of light / 12 hours of dark, the aeration rate was controlled at 1 - 5 L / min, the volume exchange rate was 50%, and it ran for 20 days; after running for 20 days, salinity acclimation of the bacteria-algae system was carried out, and the salinity was gradually increased from 0.1% to 0.3% (the salinity increased in increments of 0.1%, 0.2%, and 0.3%, and was increased to the next salinity every 7 days of acclimation). After running for 20 days, it continued to run at a salinity of 0.3% for 40 days.

[0090] The mixed liquid suspended solids (MLSS), mixed liquid volatile suspended solids (MLVSS), and chlorophyll a concentration in the 1#, 2#, 3#, and 4# reactors were respectively measured at 0 day, 40 days, and 80 days of operation to observe the growth of the bacteria-algae granular sludge. At the same time, an optical microscope and grid paper were used to measure the particle size of the bacteria-algae granular sludge and observe its particle size change.

[0091] (1) Growth of the algal-based biochar coupled with bacteria-algae granular sludge

[0092] After measurement, after running for 40 days, the sludge concentration could be maintained stably. The MLSS of 1#, 2#, 3#, and 4# were 4.1 ± 0.2 g / L, 4.8 ± 0.3 g / L, 5.1 ± 0.1 g / L, and 4.6 ± 0.4 g / L respectively, and the MLVSS / MLSS remained above 0.6. This indicated that the activities of the bacteria-algae granular sludge microorganisms in the system were all relatively high.

[0093] The influence of different biochar dosages on the particle size of the bacteria-algae granular sludge is as Figure 2 shown. As Figure 2As can be seen from the results shown, the shapes of the algal-bacterial granular sludge in groups 1#, 2#, 3#, and 4# are relatively regular circles and are dark green. After adding biochar to the average algal-bacterial granular sludge in the 4 groups, that is, after 40 days of operation, the sizes increased from 1.11±0.21 mm, 1.37±0.44 mm, 1.07±0.26 mm, and 1.04±0.21 mm to 2.09±0.62 mm, 1.87±0.59 mm, 1.58±0.69 mm, and 1.55±0.86 mm. At the same time, the granules in the experimental groups 1#, 2#, and 3# were significantly larger than those in group 4#, indicating that the coupling of biochar can increase the particle size of algal-bacterial granular sludge and strengthen the aggregation of microorganisms.

[0094] (2) Chlorophyll content changes in algal-based biochar-coupled algal-bacterial granular sludge

[0095] The effects of different biochar dosages on the chlorophyll content in algal-bacterial granular sludge are as Figure 3 shown. As Figure 3 can be seen, after 40 days of operation, the chlorophyll a concentration in group 1# was 7.9±0.2 mg / L, significantly higher than the other 3 groups (p<0.05), indicating that adding appropriate algal-based biochar has a certain promoting effect on the salinity adaptability and growth of microalgae in the system.

[0096] Example 3 Determination of the removal effect of algal-based biological coupling of algal-bacterial granular sludge on antibiotics

[0097] To further explore the removal efficiency of the algal-bacterial granular sludge system coupled with different dosages of algal-based biochar on aquaculture wastewater containing enrofloxacin, experiments were specifically conducted on the removal of carbon, nitrogen, phosphorus, and enrofloxacin in aquaculture wastewater:

[0098] First, after the system had been operating stably for 40 days, the influent water quality in the system was simulated aquaculture wastewater containing enrofloxacin (that is, adding enrofloxacin with a final concentration of 100 μg / L to the simulated wastewater described in this application), the salinity was 0.3%, the operating program and time of the photo-sequencing batch reactor were 10 minutes of influent, 90 minutes of static settlement, 210 minutes of aeration, 40 minutes of precipitation, and 10 minutes of drainage; the light / dark cycle was 12 hours of light / 12 hours of darkness, the aeration volume was controlled at 1 - 5 L / min, and the volume exchange rate was 50%. It was operated for 40 days in total. During the operation process, a high-performance liquid chromatograph was used to measure the removal of enrofloxacin in the wastewater, as well as the removal of carbon, nitrogen, and phosphorus.

[0099] 1. Removal efficiency of the algal-based biochar-coupled algal-bacterial granular sludge system on carbon, nitrogen, and phosphorus

[0100] Monitor the basic water quality of the influent and effluent of 4 groups of reactors (4 experimental groups of 1#, 2#, 3#, and 4# in Example 2) daily, and explore the removal efficiency of carbon, nitrogen, and phosphorus in aquaculture wastewater by the coupled bacteria-algae granular sludge system with different dosages of algal-based biochar. The results are as Figure 4 shown.

[0101] As Figure 4 can be seen, the removal rates of COD, NH4 + -N, and PO4 3- -P in reactors 1#, 2#, and 3# are 94.8±4.5%, 83.9±8.2%, 67.0±12.5%, 89.4±6.1%, 76.1±7.3%, 71.4±9.3%, and 92.0±7.2%, 73.1±9.4%, 65.3±12.7% respectively. For reactor 4#, the removal rates of COD, NH4 + -N, and PO4 3- -P are 88.0±8.1%, 68.8±9.3%, and 67.5±9.1% respectively. From the results, it can be concluded that adding algal-based biochar can enhance the removal efficiency of the bacteria-algae granular sludge system for carbon, nitrogen, and phosphorus. The removal efficiency of reactor 1# for COD and NH4 + -N is the most significant. It shows that when adding 1 g / L of algal-based biochar, the algal-based biochar can be well coupled with the bacteria-algae granular sludge system and has strong tolerance to the environment containing ENR.

[0102] 2. Removal efficiency of the algal-based biochar coupled bacteria-algae granular sludge system for enrofloxacin

[0103] Monitor the changes in the influent and effluent concentrations of enrofloxacin in 4 groups of reactors daily, explore the removal efficiency of the coupled bacteria-algae granular sludge system with different dosages of algal-based biochar for enrofloxacin in aquaculture wastewater, and calculate the specific removal rate (μg / g-VSS / d). The results are as Figure 5 shown. Among them, the calculation method of the specific removal rate is: (influent concentration (μg / L) - effluent concentration (μg / L)) / (mixed liquor volatile suspended solid concentration (g / L) × hydraulic retention time (days)).

[0104] As Figure 5It can be seen that the removal rates of enrofloxacin by the 1#, 2#, 3#, and 4# reactors are 60.0±4.4%, 63.6±3.2%, 62.5±4.7%, and 55.7±3.4% respectively, and the specific removal rates are 47.6±3.7 μg / g-VSS / d, 46.7±3.8 μg / g-VSS / d, 40.7±4.5 μg / g-VSS / d, and 43.9±4.6 μg / g-VSS / d respectively. This shows that the algal-based biochar can enhance the ability of the algal-bacterial granular sludge to remove enrofloxacin, and the specific removal rate of enrofloxacin by the 1# reactor is significantly higher than that of other groups.

[0105] Based on the above results, it can be known that when 1 g / L of algal-based biochar is added, the algal-bacterial inoculation ratio is 5:1, the light intensity is 1800 lux, and after 20 days of operation, the salinity of the algal-bacterial system is acclimated, with the salinity gradually increased from 0.1% to 0.3% and operated for 20 days. The resulting algal-based biochar coupled algal-bacterial granular sludge system has a high removal efficiency for carbon, nitrogen, phosphorus, and enrofloxacin in water.

[0106] Example 4 Treatment of aquaculture wastewater containing enrofloxacin by different purification systems

[0107] To compare and explore the removal efficiency of different treatment systems for simulated aquaculture wastewater containing the antibiotic enrofloxacin, the following treatment systems were used for batch removal experiments of carbon, nitrogen, phosphorus, and antibiotics.

[0108] When conducting batch removal experiments of carbon, nitrogen, and phosphorus, the treatment systems were respectively: algal solution system (Microalgae, OD 680 was 1.5), activated sludge system (Activated sludge, AS, sludge concentration was 4.5±1.0 g / L), algal-bacterial granular sludge system (MBGS, sludge concentration was 4.5±1.0 g / L), and algal-based biochar coupled algal-bacterial granular sludge system (MBGS + 1 g / L BC, sludge concentration was 4.5±1.0 g / L). When conducting batch removal experiments of antibiotics, a biochar system (BC, 1 g / L) was added to the above treatment systems. The reaction system was pre-filled with simulated wastewater in a photo-sequencing batch reactor with COD, NH4 + -N, PO4 3- -P, and ENR concentrations of 1000 mg / L, 100 m / L, 10 mg / L, 100 μg / L, and a salinity of 0.3%. Under the conditions of 250 rpm, 25 °C, and 1800 lux, it was shaken and treated for 48 h. The removal of enrofloxacin in the wastewater was measured using a high-performance liquid chromatograph, and the removal of carbon, nitrogen, and phosphorus in the simulated wastewater was also measured.

[0109] 1. Removal Efficiencies of Carbon, Nitrogen, and Phosphorus by Four Treatment Systems of Microalgae, AS, MBGS, and MBGS + 1 g / L BC

[0110] The basic water quality of the influent and effluent of the four treatment systems was monitored to explore the removal efficiencies of carbon, nitrogen, and phosphorus by the four purification systems. The results are as Figure 6 shown. The results indicate that the removal efficiencies of the algal solution for COD, NH4 + -N, and were 23.7 ± 2.4%, 29.9 ± 3.5%, and 46.9 ± 2.9% respectively, and the removal efficiencies of the activated sludge were 72.4 ± 6.4%, 56.0 ± 6.5%, and 57.0 ± 6.8% respectively; the removal efficiencies of the microbial-algal granular sludge were increased to 88.0 ± 7.1%, 72.7 ± 7.3%, and 67.0 ± 9.1% respectively; the removal efficiencies of the biochar-coupled microbial-algal granular sludge (MBGS + BC) were further enhanced, reaching 94.8 ± 4.5%, 89.4 ± 8.2%, and 67.5 ± 8.3% respectively. This shows that microalgae and activated sludge exhibit a synergistic wastewater treatment effect in the microbial-algal granular sludge system.

[0111] 2. Removal Efficiencies of Enrofloxacin by Five Purification Systems of 1 g / L BC, Microalgae, AS, MBGS, and MBGS + 1 g / L BC

[0112] The changes in the influent and effluent concentrations of enrofloxacin in the five treatment systems were monitored at regular intervals to compare the removal efficiencies of enrofloxacin by different treatment systems (biochar, algal solution, activated sludge, microbial-algal granular sludge, and biochar-coupled microbial-algal granular sludge). The results are as Figure 7 shown. The results indicate that the removal efficiencies of the algal solution, activated sludge, and microbial-algal granular sludge for enrofloxacin were 29.0 ± 3.2%, 44.6 ± 2.8%, and 56.7 ± 3.5% respectively, while the removal efficiency of the biochar-coupled microbial-algal granular sludge group (MBGS + 1 g / L BC) was significantly increased to 74.3%. This shows that microalgae and activated sludge exhibit a synergistic effect in the microbial-algal granular sludge system, and the introduction of algal-based biochar further enhances the removal ability of the system for enrofloxacin in high-salt wastewater, verifying the application potential of this technology in complex wastewater treatment.

[0113] In summary, the algal-based biochar-coupled microbial-algal granular sludge system has high removal efficiencies for carbon, nitrogen, phosphorus, and enrofloxacin antibiotics in aquaculture wastewater, and its removal effect is stable, showing good application prospects for treating aquaculture wastewater.

[0114] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for cultivating biochar-coupled bacterial-algal granular sludge, characterized in that: The following steps are involved: S1. Take the activated sludge from the secondary sedimentation tank of the sewage treatment plant and put it into the photo-sequential batch reactor. + -N and PO4 3 -P solution is used for domestication and cultivation to obtain flocculent activated sludge; S2. Add OD to the flocculent activated sludge obtained in S1 at a volume ratio of sludge to Chlorella liquid of 3 to 10:1 680 The method comprises the following steps: adding 1 to 2 g / L of Chlorella liquid to a final concentration of 1 to 3 g / L of biochar for co-cultivation to obtain biochar-coupled bacteria-algae granular sludge.

2. The method according to claim 1, characterized in that: The operation procedure and time of the photo-sequential batch reactor are: 9 to 11 minutes for water intake, 88 to 92 minutes for standing, 208 to 212 minutes for aeration, 38 to 42 minutes for sedimentation, and 9 to 11 minutes for drainage; the aeration volume is controlled at 1 to 5 L / min; wherein, the hydraulic retention time in S1 is 12 hours; S2 requires illumination, the illumination intensity is: 800 to 2500 lux, and the light / dark cycle is 12 hours of light / 12 hours of darkness.

3. The method according to claim 2, characterized in that: In the solution described in S1, the concentration of COD is 900-1100 mg / L, NH4 + -N concentration is 90~110mg / L, PO4 3 The concentration of -P is 9-11 mg / L.

4. The method according to claim 3, characterized in that: The algae species number of Chlorella described in S2 is FACHB-11.

5. The method according to claim 4, characterized in that: The biochar described in S2 is algae-based biochar obtained by pyrolysis of Chlorella.

6. The biochar-coupled bacteria-algae granular sludge prepared by the method according to any one of claims 1 to 5.

7. A biochar coupled bacteria-algae granular sludge system, characterized in that: The system comprises a photosequential batch reactor and the biochar-coupled bacteria-algae granular sludge as described in claim 6.

8. Use of the biochar-coupled bacteria-algae granular sludge according to claim 6 or the system according to claim 7 in removing quinolone antibiotics from water.

9. Use of the biochar-coupled bacteria-algae granular sludge according to claim 6 in the preparation of a preparation for removing quinolone antibiotics from water.

10. Use of the system according to claim 7 in preparing a device for removing quinolone antibiotics from water.

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