Biochar-coupled bacteria-algae granular sludge, and a cultivation method and application thereof

Abstract

The application discloses a kind of biochar coupling bacteria-algae granular sludge and its culture method and application.The application utilizes activated sludge of sewage treatment plant secondary sedimentation tank, chlorella and biochar in light sequence batch reactor, and a kind of biochar coupling bacteria-algae granular sludge is obtained by cultivation, using it can efficiently remove COD, NH4 + -N, PO4 3 -P and antibiotic (such as enoxacin) and other pollutants contained in aquaculture wastewater under the condition of salinity 0.3%.In addition, the stability of the biochar coupling bacteria-algae granular sludge described in the application is good, and when using it to treat antibiotic pollutants, the removal rate of antibiotic pollutants does not decrease with the extension of time, which is beneficial to the efficient and stable removal of COD, NH4 + -N, PO4 3 -P and antibiotic and other pollutants, and has good application prospect in aquaculture wastewater treatment.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture wastewater treatment technology, specifically relating to a biochar coupled with bacterial and algal granular sludge, its cultivation method, and its application. Background Technology

[0002] Aquaculture wastewater contains large amounts of organic matter and ammonia nitrogen (NH4). + -N) and phosphorus (PO4) 3- Pollutants such as nitrogen oxides (NOx) discharged untreated into surrounding water bodies can lead to eutrophication, impacting the habitat of aquatic organisms. Furthermore, the use of quinolone antibiotics (such as enrofloxacin (ENR)) or other drugs in aquaculture to control diseases results in antibiotic residues in aquaculture wastewater, posing a threat to ecological security and human health. Therefore, the treatment of aquaculture wastewater must remove not only organic matter and ammonia nitrogen but also antibiotic residues. The efficient removal of these complex pollutants has become a key task in protecting the ecological environment and deepening pollution and carbon reduction efforts.

[0003] Currently, the main treatment methods for aquaculture wastewater fall into three categories: physical, chemical, and biological treatment. Biological treatment methods include activated sludge processes, biofilm processes, algae treatment, and in-situ treatment using microbial agents. The activated sludge process is a traditional biological treatment technology for aquaculture wastewater, effectively removing organic matter and suspended solids, and offering advantages such as environmental friendliness and sustainability. However, the activated sludge process also has drawbacks. For example, it produces a large amount of sludge, increasing treatment costs and environmental burden; it is also time-consuming, and its removal efficiency for pollutants such as nitrogen and phosphorus is limited. Microbial-algae granular sludge (MBGS) has attracted widespread attention due to its effective removal of organic matter, ammonia nitrogen, and phosphates from wastewater; however, there are few reports on its use for antibiotic removal. Furthermore, with prolonged treatment time, the selective pressure of antibiotics leads to a significant decrease in the metabolic activity of the microbial-algae granular sludge, resulting in fluctuations and instability in antibiotic removal efficiency. In actual operation, pollutants from aquaculture wastewater are continuously fed into treatment systems containing only bacterial and algal granular sludge, which lack a mechanism for regular renewal or replacement. Therefore, the activity decay of the bacterial and algal granular sludge during long-term operation hinders its efficient and stable removal of antibiotic pollutants. Consequently, optimizing the performance of bacterial and algal granular sludge to improve its degradation efficiency for antibiotic pollutants and maintain its long-term operational stability has become a critical scientific problem that urgently needs to be solved in the application of bacterial and algal granular sludge technology in aquaculture wastewater treatment. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides a biochar-coupled bacterial-algae granular sludge, its cultivation method, and its application.

[0005] The first objective of this invention is to provide a method for cultivating biochar coupled with bacterial and algal granular sludge.

[0006] The second objective of this invention is a biochar coupled with bacterial and algal granular sludge.

[0007] A third objective of this invention is to provide the application of the biochar-coupled algal granular sludge or the system of claim 7 in the removal of quinolone antibiotics from water.

[0008] A fourth object of the present invention is to provide the use of the biochar coupled with algal particles in the preparation of formulations for removing quinolone antibiotics from water.

[0009] A fifth object of the present invention is to provide the application of the system in the preparation of an apparatus for removing quinolone antibiotics from water.

[0010] The above-mentioned objective of this invention is achieved through the following technical solution:

[0011] This invention utilizes activated sludge, Chlorella, and biochar from the secondary sedimentation tank of a wastewater treatment plant in a photosequential batch reactor to cultivate a biochar-coupled algae-bacterial granular sludge. This sludge can efficiently remove COD and NH4 from aquaculture wastewater under high salinity (0.3%) conditions. + -N,PO4 3 -P and antibiotics (such as enrofloxacin) and other contaminants, with stable removal efficiency for antibiotic contaminants. Therefore, this invention claims protection for the biochar coupled with bacterial and algal granular sludge, its cultivation method, and its application.

[0012] This invention provides a method for cultivating biochar coupled with bacterial and algal granular sludge, comprising the following steps:

[0013] S1. Take activated sludge from the secondary sedimentation tank of a wastewater treatment plant and feed it into a photocatalytic batch reactor containing COD and NH4+. + -N and PO4 3 The flocculent activated sludge was obtained by acclimatization and cultivation in a solution containing -P.

[0014] S2. Add OD to the flocculent activated sludge obtained in S1 at a sludge-to-Chlorella liquid volume ratio of 3-10:1. 680 A solution of Chlorella with a concentration of 1-2 g / L was added to biochar with a final concentration of 1-3 g / L for co-cultivation to obtain biochar-coupled algae-bacteria granular sludge.

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

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

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

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

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

[0020] S11. Pretreatment of activated sludge: The activated sludge collected from the secondary sedimentation tank of the wastewater treatment plant is sieved, and after it is allowed to stand, the supernatant is poured out to complete the pretreatment of activated sludge.

[0021] S12. Place the pretreated activated sludge in a photocatalytic batch reactor. The operating procedure and time are as follows: 9–11 minutes for influent, 88–92 minutes for settling, 208–212 minutes for aeration, 38–42 minutes for sedimentation, and 9–11 minutes for effluent. The hydraulic retention time is 12 hours, the aeration rate is controlled at 1–5 L / min, and the volume exchange rate is 50%. Continue to acclimatize and cultivate the sludge under the above conditions until it can effectively control COD and 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 activated sludge collected from the secondary sedimentation tank of the wastewater treatment plant was 10.0 ± 1.0 g / L.

[0023] Specifically, the sieving described in S11 refers to passing the material through a 100-mesh sieve three times.

[0024] Specifically, the reaction temperature in S12 is 24℃~26℃.

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

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

[0027] Specifically, the species of Chlorella described in S2 is FACHB-11, which was purchased from the Freshwater Algae Culture Collection of the Chinese Academy of Sciences.

[0028] Specifically, the biochar mentioned in S2 is algal-based biochar obtained by pyrolysis of Chlorella.

[0029] Specifically, the pyrolysis process is as follows: the lyophilized Chlorella powder is dried and then pulverized, heated at 600-800°C for 1-3 hours under constant temperature, oxygen-deficient, and nitrogen-containing conditions, cooled to room temperature, pulverized, ground, and sieved to obtain the algae-based biochar.

[0030] More specifically, the Chlorella species is numbered FACHB-11, enabling the secondary utilization of Chlorella.

[0031] More specifically, the Chlorella freeze-dried powder is dried and then pulverized using a pulverizer. The resulting powder is compacted and placed into a covered crucible. The crucible is then transferred to a muffle furnace and heated for 2 hours under constant temperature (700℃) and oxygen-deficient nitrogen conditions. After cooling to room temperature, the powder is removed, pulverized and ground using a pulverizer, and passed through a 100-mesh sieve to obtain the algae-based biochar.

[0032] In a specific embodiment of the present invention, the method for culturing the Chlorella liquid is as follows: Chlorella liquid and BG-11 liquid culture medium are inoculated sequentially at volume ratios of 1:1, 1:5, and 1:10, and then cultured under conditions of light intensity of 2000 lux and temperature of 25°C.

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

[0034] More preferably, in S2, the flocculent activated sludge obtained in S1 is mixed with OD680 Chlorella solutions of 1-2 were mixed at a volume ratio of 5:1, and biochar with a final concentration of 1 g / L was added for co-cultivation to obtain biochar coupled with bacteria and algae granular sludge.

[0035] Specifically, the cultivation described in S2 is carried out in a photo-sequential batch reactor; wherein the light intensity of the photo-sequential batch reactor is 800-2500 lux, and the operating procedure and time are as follows: 9-11 minutes of water inlet, 88-92 minutes of settling, 208-212 minutes of aeration, 38-42 minutes of sedimentation, and 9-11 minutes of drainage; the light / dark cycle is 12 hours of light / 12 hours of darkness, 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-sequential batch reactor is 1800–2500 lux.

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

[0038] During the cultivation of bacterial and algal granular sludge, the cultivation temperature is 24–26℃.

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

[0040] More specifically, in S2, the culture time after adding Chlorella solution is 20 days.

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

[0042] The present invention also provides a biochar coupled with algae granular sludge system, the system comprising a photo-sequential batch reactor and the biochar coupled with algae granular sludge described in the present invention.

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

[0044] S1. Take activated sludge from the secondary sedimentation tank of a wastewater treatment plant and place it in a photocatalytic batch reactor, using a solution containing COD and NH4+. + -N and PO4 3 Flocculent activated sludge was obtained by acclimation and cultivation in a solution containing -P; the concentration of COD in the solution was 900-1100 mg / L and NH4+. + The concentration of -N is 90–110 mg / L, PO4 3 The concentration of -P is 9–11 mg / L;

[0045] S2. To the flocculent activated sludge obtained in S1, add OD at a volume ratio of 3 to 10:1 between the flocculent activated sludge and the Chlorella solution. 680 For a Chlorella solution of 1-2, a photo-sequential batch reactor was set with a light intensity of 800-2500 lux. The operating procedure and time were as follows: 9-11 minutes for water inlet, 88-92 minutes for settling, 208-212 minutes for aeration, 38-42 minutes for sedimentation, and 9-11 minutes for drainage. The light / dark cycle was 12 hours of light / 12 hours of darkness. The aeration rate was controlled at 1-5 L / min, the volume exchange rate was 50%, and the culture time was 20-30 days.

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

[0047] In a specific embodiment of the present invention, after culturing in S3 for 20 days, the resulting system was subjected to salinity acclimatization; the salinity was gradually increased from 0.1% to 0.3%, with the salinity increasing in increments of 0.1%, 0.2%, and 0.3%, and the next salinity was increased every 7 days.

[0048] Given that the biochar-coupled algae-bacterial granular sludge described in this invention can effectively remove enrofloxacin (a quinolone antibiotic) from water, this invention also claims protection for the use of the biochar-coupled algae-bacterial granular sludge or the biochar-coupled algae-bacterial granular sludge system in removing quinolone antibiotics from water.

[0049] The present invention also claims protection for the use of the biochar-coupled algal granular sludge in the preparation of formulations for removing quinolone antibiotics from water.

[0050] The present invention also claims protection for the use of the system in the preparation of an apparatus for removing quinolone antibiotics from water.

[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] This invention utilizes activated sludge, Chlorella, and biochar from the secondary sedimentation tank of a wastewater treatment plant in a photosequential batch reactor to cultivate a dense biochar-coupled algae-bacterial granular sludge. This sludge can efficiently remove COD and NH4 from aquaculture wastewater under a salinity of 0.3%. + -N,PO4 3-P and antibiotics (such as enrofloxacin). Furthermore, the biochar-coupled algae-bacterial granular sludge described in this invention exhibits good stability; when used to treat antibiotic pollutants, the removal rate does not decrease over time, which is beneficial for reducing COD and NH4 in aquaculture wastewater. + -N,PO4 3 The efficient and stable removal of pollutants such as -P and antibiotics has promising application prospects in the treatment of aquaculture wastewater. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of the small-scale photo-sequential batch reactor constructed in this invention; in the figure, Influent is the influent system, Effluent is the effluent system, Light is the illumination system, and Aeration is the aeration system.

[0056] Figure 2 The effect of different biochar dosages on the particle size of algae and bacteria granular sludge; scale bar is 1 cm.

[0057] Figure 3 The effect of different biochar dosages on the chlorophyll content in granular sludge.

[0058] Figure 4 The removal rates of carbon, nitrogen, and phosphorus in aquaculture wastewater were determined by a bacterial-algae granular sludge system coupled with different amounts of algae-based biochar.

[0059] Figure 5 The removal rate and specific removal rate of enrofloxacin in aquaculture wastewater were determined by a bacterial-algae granular sludge system coupled with different amounts of algae-based biochar.

[0060] Figure 6 The removal rates of carbon, nitrogen, and phosphorus in aquaculture wastewater were determined by algal liquid system, activated sludge system, algal-bacterial granular sludge system, and algal-based biochar coupled with algal-bacterial granular sludge system.

[0061] Figure 7 This study analyzes the removal efficiency of enrofloxacin in aquaculture wastewater by biochar systems, algal liquid systems, algal-based biochar systems, activated sludge systems, bacterial-algal granular sludge systems, and algal-based biochar coupled with bacterial-algal granular sludge systems.

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

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

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

[0065] To facilitate the cultivation of bacterial and algal granular sludge under laboratory conditions, this invention constructs a small-scale photo-sequential batch reactor, including a reactor, a lighting system, an aeration system, a timing system, and an influent / effluent system (including a peristaltic pump), as shown in the schematic diagram below. Figure 1 As shown (the timing system is not shown in the figure); the reactor is made of transparent PVC material, 60cm high, 7cm inner diameter, and has an effective volume of 2L. One operating cycle of the photo-sequential batch reactor consists of 5 stages: influent, settling, aeration, sedimentation, and drainage, with a light / dark cycle of 12 hours of light / 12 hours of darkness.

[0066] Example 1: Cultivation of bacterial and algal granular sludge

[0067] The granular sludge described in this embodiment is obtained by mixing flocculent activated sludge obtained through acclimatization cultivation of Chlorella sp. culture medium with activated sludge, followed by cultivation in a photocatalytic batch reactor using simulated wastewater. The Chlorella sp. was purchased from the Freshwater Algae Bank of the Chinese Academy of Sciences, with the species number FACHB-11. The activated sludge is activated sludge from the secondary sedimentation tank of a wastewater treatment plant. The composition of the simulated wastewater (per 20L) is as follows:

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

[0069] 1. Enrichment culture of Chlorella

[0070] The purchased Chlorella solution was inoculated with BG-11 liquid culture medium at volume ratios of 1:1, 1:5, and 1:10, respectively. The culture was then placed under conditions of 2000 lux light intensity and 25℃, and manually shaken the flask 3-4 times daily to prevent sticking. The culture was continued until the OD reached [the specified OD value]. 680 Chlorella solution was collected at 1.5°C. After cultivation, a homogeneous Chlorella solution with a volume of approximately 2 L was obtained.

[0071] 2. Acclimation and cultivation of activated sludge

[0072] In this embodiment, the initial concentration of activated sludge collected from the secondary sedimentation tank was 10.0±1.0 g / L. It was pretreated and then acclimatized and cultured.

[0073] The pretreatment method for activated sludge is as follows: The collected activated sludge from the secondary sedimentation tank is passed through a 100-mesh sieve three times. After settling, the supernatant is poured off, completing the pretreatment of the activated sludge. The acclimation and cultivation method is as follows: The pretreated activated sludge is placed in a photocatalytic batch reactor at 25°C. The reactor is set with a 10-minute influent (simulated wastewater), 90-minute settling, 210-minute aeration, 40-minute sedimentation, and 10-minute effluent discharge. The hydraulic retention time is 12 hours, the aeration rate is controlled at 1–5 L / min, and the volume exchange rate is 50%. Acclimation and cultivation are continued under these conditions for at least 30 days until the activated sludge exhibits its ability to regulate COD and NH4+. + -N and PO4 3 -P removal rate remained stable and its MLVSS / MLSS ratio also remained stable, resulting in flocculent activated sludge.

[0074] 3. Optimization of cultivation conditions for bacterial and algal granular sludge

[0075] First, the operating program and time of the photo-sequential batch reactor were set as follows: 10 minutes of influent (the simulated wastewater), 90 minutes of settling, 210 minutes of aeration, 40 minutes of sedimentation, and 10 minutes of effluent discharge; the light / dark cycle was 12 hours of light / 12 hours of darkness, the aeration rate was controlled at 1–5 L / min, and the light intensity was 4000 lux. Under these conditions, the flocculent activated sludge obtained from acclimatization and cultivation (sludge concentration of 4.5 ± 1.0 g / L) was mixed with enriched Chlorella solution (OD200). 680 The bacteria and algae were mixed at volume ratios of 3:1, 5:1 and 10:1 respectively, and run in a photo-sequential batch reactor for 30 days to obtain granular sludge. The removal efficiency of carbon, nitrogen and phosphorus and the average particle size were monitored daily.

[0076] Table 1. Effects of bacterial / algae inoculation ratio on carbon, nitrogen, and phosphorus removal efficiency and average particle size.

[0077]

[0078] As shown in Table 1, the optimal bacterial-algae inoculation ratio is 5:1.

[0079] Keeping the operating procedure and time of the photosequential batch reactor unchanged, the flocculent activated sludge (sludge concentration of 4.5±1.0 g / L) obtained from acclimatization and cultivation was mixed with the enriched Chlorella solution (OD200). 680Mix the 1.5) at a volume ratio of 5:1, and set the light intensity (the light intensity is achieved by changing the number of LED strips) to 2500 lux, 1800 lux, and 800 lux respectively. Run the mixture in a photo-sequential batch reactor for 30 days to obtain algal granular sludge. Monitor its removal efficiency of carbon, nitrogen, and phosphorus, as well as the average particle size, etc., every day.

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

[0081]

[0082] As shown in Table 2, the optimal light intensity is 1800 lux.

[0083] Through optimization, the present invention obtained the optimal conditions for cultivating the bacterial and algal granular sludge. Based on this, a photocatalytic batch reactor was run under these optimized conditions for 20 days. The results showed that the bacterial and algal granular sludge cultivation system stabilized after 20 days of cultivation, with the granular sludge particle size approximately 1.5 mm, and exhibiting good control over COD and NH4+. + -N and PO4 3- The removal rates of -P were 79.9±4.0%, 71.9±9.9%, and 62.8±7.0%.

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

[0085] Example 2: Cultivation of algae-based biochar coupled with bacterial and algae granular sludge

[0086] 1. Preparation of algae-based biochar

[0087] Chlorella powder (FACHB-11) was freeze-dried in an 80℃ oven to dry the moisture. Then, it was pulverized with a pulverizer. The resulting powder was compacted and placed in a covered crucible. The crucible was then transferred to a muffle furnace and heated for 2 hours under constant temperature (700℃) and oxygen-deficient nitrogen conditions. After cooling to room temperature, it was taken out, pulverized and ground with a pulverizer, and passed through a 100-mesh sieve to obtain Chlorella biochar (the algae-based biochar). It was then placed in a white transparent wide-mouth bottle for later use.

[0088] 2. Optimization of culture conditions for algae-based biochar coupled with bacterial and algae granular sludge

[0089] 2g, 4g, 6g, and 0g of the prepared algae-based biochar were respectively added to four algae-bacterial photoreactors, i.e., the biochar dosage was set at 1g / L, 2g / L, 3g / L, and 0g / L (named 1#, 2#, 3#, and 4#). The flocculent activated sludge (sludge concentration of 4.5±1.0g / L) obtained by acclimatization and cultivation in the photoreactors was mixed with Chlorella liquid (OD). 680 The volume ratio of the bacteria and algae was 5:1 (1.5), the light intensity was 1800 lux (obtained from the previous cultivation), and the operation procedure and time of the photo-sequential batch reactor were as follows: 10 minutes of water inlet (the simulated wastewater), 90 minutes of settling, 210 minutes of aeration, 40 minutes of sedimentation, and 10 minutes of drainage; the light / dark cycle was 12 hours of light / 12 hours of darkness, the aeration rate was controlled at 1-5 L / min, the volume exchange rate was 50%, and the system was run for 20 days; after 20 days of operation, the salinity of the bacterial-algae system was acclimatized, and the salinity was gradually increased from 0.1% to 0.3% (the salinity was increased in increments of 0.1%, 0.2%, and 0.3%, with each acclimatization period lasting 7 days to the next salinity), and after 20 days of operation, the salinity was maintained at 0.3% for another 40 days.

[0090] The concentrations of mixed liquid suspended solids (MLSS), mixed liquid volatile suspended solids (MLVSS), and chlorophyll a were measured in reactors #1, #2, #3, and #4 at 0 days, 40 days, and 80 days of operation, respectively, to observe the growth of the bacterial and algal granular sludge. At the same time, the particle size of the bacterial and algal granular sludge was measured using an optical microscope and grid paper to observe its particle size changes.

[0091] (1) Growth of algae-based biochar coupled with bacterial and algae granular sludge

[0092] After 40 days of operation, the sludge concentration remained stable. 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 ratio remained above 0.6. This indicates that the activity of microorganisms in the granular sludge of bacteria and algae in the system was high.

[0093] The effects of different biochar dosages on the particle size of granular sludge are as follows: Figure 2 As shown. By Figure 2The results show that the granular sludge from the four groups (1#, 2#, 3#, and 4#) is relatively regularly shaped and dark green. After the addition of biochar and 40 days of operation, the average particle size of the granular sludge from the four groups increased from 1.11±0.21mm, 1.37±0.44mm, 1.07±0.26mm, and 1.04±0.21mm to 2.09±0.62mm, 1.87±0.59mm, 1.58±0.69mm, and 1.55±0.86mm, respectively. Furthermore, the particles from experimental groups 1#, 2#, and 3# are significantly larger than those from group 4#. This indicates that the addition of biochar can increase the particle size of the granular sludge and enhance microbial aggregation.

[0094] (2) Changes in chlorophyll content of algae-based biochar coupled with bacterial and algae granular sludge

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

[0096] Example 3: Determination of the antibiotic removal effect of algae-based biocoupled bacterial-algae granular sludge.

[0097] To further investigate the removal efficiency of different algae-based biochar dosage coupled with a bacterial-algae granular sludge system on aquaculture wastewater containing enrofloxacin, experiments were conducted on the removal of carbon, nitrogen, phosphorus, and enrofloxacin from the aquaculture wastewater:

[0098] First, after the system had been running stably for 40 days, the influent water was simulated aquaculture wastewater containing enrofloxacin (i.e., enrofloxacin with a final concentration of 100 μg / L added to the simulated wastewater described in this application), with a salinity of 0.3%. The operating procedure and time of the photo-sequential batch reactor were as follows: 10 minutes of influent, 90 minutes of settling, 210 minutes of aeration, 40 minutes of sedimentation, and 10 minutes of effluent discharge; the light / dark cycle was 12 hours of light / 12 hours of darkness, the aeration rate was controlled at 1-5 L / min, and the volume exchange rate was 50%. The system was run for a total of 40 days. During the operation, high performance liquid chromatography was used to determine the removal of enrofloxacin in the wastewater, as well as the removal of carbon, nitrogen, and phosphorus.

[0099] 1. The carbon, nitrogen, and phosphorus removal efficiency of the algae-based biochar coupled with granular bacteria and algae sludge system.

[0100] The basic influent and effluent water quality of four reactors (the four experimental groups #1, #2, #3, and #4 in Example 2) were monitored daily to explore the removal efficiency of carbon, nitrogen, and phosphorus from aquaculture wastewater by different amounts of algae-based biochar coupled with a bacterial-algae granular sludge system. The results are as follows: Figure 4 As shown.

[0101] Depend on Figure 4 It can be seen that reactors #1, #2, and #3 have a significant impact on COD and NH4+. + -N and PO4 3- The removal rates of -P were 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, while the removal rates of COD and NH4 in reactor #4 were... + -N and PO4 3- The removal rates of -P were 88.0±8.1%, 68.8±9.3%, and 67.5±9.1%, respectively. The results indicate that adding algae-based biochar can enhance the removal efficiency of carbon, nitrogen, and phosphorus in the algae-bacterial granular sludge system. Reactor #1 showed improved removal efficiency for COD and NH4+. + The removal efficiency of -N is the most significant. This indicates that adding 1 g / L of algae-based biochar can effectively couple with the bacterial and algae granular sludge system and has strong tolerance to environments containing ENR.

[0102] 2. Removal efficiency of enrofloxacin by algae-based biochar coupled with bacterial and algae granular sludge system

[0103] The influent and effluent concentrations of enrofloxacin in four reactor groups were monitored daily to investigate the removal efficiency of different algae-based biochar dosage coupled with a bacterial-algae granular sludge system for enrofloxacin removal from aquaculture wastewater. The specific removal rate (μg / g-VSS / d) was calculated. The results were presented by... Figure 5 As shown. The specific removal rate is calculated as follows: (influent concentration (μg / L) - effluent concentration (μg / L)) / (volatile suspended solids concentration of mixed liquor (g / L) × hydraulic retention time (days)).

[0104] Depend on Figure 5The results showed that the removal rates of enrofloxacin by reactors #1, #2, #3, and #4 were 60.0±4.4%, 63.6±3.2%, 62.5±4.7%, and 55.7±3.4%, respectively, and the specific removal rates were 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 indicates that algae-based biochar can enhance the removal capacity of enrofloxacin by algae-bacterial granular sludge, and the specific removal rate of enrofloxacin by reactor #1 was significantly higher than that of the other groups.

[0105] Based on the above results, it can be seen that adding 1 g / L of algae-based biochar, with an algae-to-bacterial inoculation ratio of 5:1, a light intensity of 1800 lux, and running for 20 days followed by salinity acclimatization of the algae-bacterial system by gradually increasing the salinity from 0.1% to 0.3% for another 20 days, the resulting algae-based biochar coupled with algae-bacterial granular sludge system exhibits high removal efficiency for carbon, nitrogen, phosphorus, and enrofloxacin in the water.

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

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

[0108] When conducting batch removal experiments of carbon, nitrogen, and phosphorus, the treatment systems are respectively: Microalgae (OD) system. 680 The following systems were used for antibiotic removal: 1.5 g / L activated sludge system (AS, 4.5 ± 1.0 g / L), 4.5 ± 1.0 g / L algal granular sludge system (MBGS, 4.5 ± 1.0 g / L), and 4.5 ± 1.0 g / L algal-based biochar coupled with 1 g / L algal granular sludge system (MBGS + 1 g / L BC, 4.5 ± 1.0 g / L). For batch antibiotic removal experiments, a biochar system (BC, 1 g / L) was added to the above treatment systems. The reaction system was pre-loaded with COD and NH4+. + -N,PO4 3- Enrofloxacin removal from the wastewater was determined using a photo-sequential batch reactor with P and ENR concentrations of 1000 mg / L, 100 mg / L, 10 mg / L, and 100 μg / L, and a salinity of 0.3%. The wastewater was treated with full shaking at 250 rpm, 25 °C, and 1800 lux for 48 h. The removal of enrofloxacin from the wastewater was determined using high performance liquid chromatography (HPLC), as were the removal of carbon, nitrogen, and phosphorus from the simulated wastewater.

[0109] 1. The removal efficiency of four treatment systems—Microalgae, AS, MBGS, and MBGS + 1g / L BC—for carbon, nitrogen, and phosphorus.

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

[0111] 2. The removal efficiency of the five purification systems (1g / L BC, Microalgae, AS, MBGS, and MBGS+1g / L BC) for enrofloxacin.

[0112] The influent and effluent concentrations of enrofloxacin in five treatment systems were monitored regularly. The removal efficiency of different treatment systems (biochar, algal liquid, activated sludge, granular sludge of bacteria and algae, and biochar coupled with granular sludge of bacteria and algae) for enrofloxacin was compared. The results are as follows: Figure 7 As shown in the figure, the removal efficiencies of algal solution, activated sludge, and algal-bacterial granular sludge for enrofloxacin were 29.0±3.2%, 44.6±2.8%, and 56.7±3.5%, respectively. The removal efficiency of the biochar-coupled algal-bacterial granular sludge group (MBGS+1g / L BC) was significantly improved to 74.3%. This indicates that microalgae and activated sludge exhibit a synergistic effect in the algal-bacterial granular sludge system. Furthermore, the introduction of algal-based biochar further enhanced the system's ability to remove enrofloxacin from high-salt wastewater, validating the application potential of this technology in complex wastewater treatment.

[0113] In summary, the algae-based biochar coupled with bacterial and algae granular sludge system has high removal efficiency for carbon, nitrogen, phosphorus, and enrofloxacin antibiotics in aquaculture wastewater, and its removal effect is stable, showing good application prospects for the treatment of 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 changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for cultivating biochar coupled with bacterial and algal granular sludge, characterized in that, Includes the following steps: S1. Take activated sludge from a secondary sedimentation tank of a sewage treatment plant and place it in a light sequencing batch reactor, and domesticate and cultivate it using a solution containing COD, NH4 + -N and PO4 3 -P, wherein 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, to obtain flocculent activated sludge; S2. To the flocculent activated sludge obtained in S1, add OD at a volume ratio of 3 to 10:1 between the flocculent activated sludge and the Chlorella solution. 680 For a Chlorella solution of 1-2, a photo-sequential batch reactor was set with a light intensity of 800-2500 lux. The operating procedure and time were as follows: 9-11 minutes for water inlet, 88-92 minutes for settling, 208-212 minutes for aeration, 38-42 minutes for sedimentation, and 9-11 minutes for drainage. The light / dark cycle was 12 hours of light / 12 hours of darkness. The aeration rate was controlled at 1-5 L / min, the volume exchange rate was 50%, and the culture time was 20-30 days. After the S3 and S2 cultures are completed, biochar with a final concentration of 1-3 g / L is added, and the cultures are co-cultured for at least 20 days under the same conditions as S2 to obtain biochar coupled with algal granular sludge; the biochar is algal-based biochar obtained by pyrolysis of Chlorella.

2. The method according to claim 1, characterized in that, The species number of Chlorella mentioned in S2 is FACHB-11.

3. Biochar-coupled algae-bacterial granular sludge prepared by the method of claim 1 or 2.

4. A biochar coupled with algae-bacterial granular sludge system, characterized in that, The system includes a photo-sequential batch reactor and the biochar-coupled algal granular sludge as described in claim 3.

5. The application of the biochar coupled with algae and bacteria granular sludge as described in claim 3 or the system as described in claim 4 in the removal of quinolone antibiotics from water, characterized in that... The quinolone antibiotic in question is enrofloxacin.

6. The application of the biochar-coupled algal granular sludge according to claim 3 in the preparation of formulations for removing quinolone antibiotics from water, characterized in that, The quinolone antibiotic in question is enrofloxacin.

7. The application of the system of claim 4 in the preparation of an apparatus for removing quinolone antibiotics from water, characterized in that, The quinolone antibiotic in question is enrofloxacin.

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