A biological fluidized bed immobilized microorganism wastewater treatment device and method

Abstract

The application belongs to the technical field of water treatment and specifically relates to a kind of biological fluidized bed immobilized microorganism wastewater treatment device and method, which is a tank structure, and a biological reaction zone is arranged in the tank; the biological reaction zone comprises a fixed plate and embedded beads, the fixed plate comprises a first fixed plate and a second fixed plate, and the embedded beads are arranged between the first fixed plate and the second fixed plate; the embedded beads are composed of polyvinyl alcohol, sodium alginate, nano-modified biochar and antibiotic-degrading bacteria. The application creatively combines the biological fluidized bed with the immobilized microorganism technology, so that the microorganisms can be stably attached to the carrier, which not only improves the utilization rate of the microorganisms, but also enhances their resistance to harsh environments; the biological fluidized bed makes the microorganism carrier particles in a fluidized state in the fluid, increases the contact area between the microorganisms and the substrate, and thus improves the mass transfer efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a biological fluidized bed immobilized microorganism wastewater treatment device and method. BACKGROUND

[0002] The biological fluidized bed is a biological membrane method for treating wastewater, and is a device for high-efficiency biological treatment by using filter material covered with biological membrane, with oxygenated wastewater passing through the fine filter material bed from bottom to top. The biological fluidized bed process overcomes the problems of ordinary activated sludge method, such as low content of microorganisms, low biological activity, and unstable treatment effect. The biological fillers of the biological fluidized bed can be divided into inorganic biological fillers, organic biological fillers, and composite biological fillers according to components. The biological fillers used in the fluidized bed mainly play a role in fixing biological membrane and providing microorganisms for attachment and growth. However, the existing biological fillers mainly form a membrane on the surface, and the formation and renewal speed of the biological membrane is slow and the amount is small.

[0003] The immobilized microorganism technology refers to a method for fixing microorganisms in a specific space by a specific method, maintaining the activity and enabling repeated use, and the method includes adsorption method, embedding method, etc. The immobilized microorganism technology can increase the concentration of microorganisms in the biological reactor, is beneficial to the separation of solids and liquids after reaction, and thus reduces the treatment time. However, the existing immobilized microorganisms are unevenly distributed in the carrier, the biomass concentration is low, and the blockage is easy to form. In addition, in the running process of the existing equipment on the market, the particles in the biological fluidized bed are suspended in the fluidized bed, the gas-solid contact area is large, the diffusion resistance is reduced, the reaction speed is large in the fluidization process, and the wear between the carrier particles and the reactor wall occurs, thereby shortening the service life of the immobilized small balls. SUMMARY

[0004] The purpose of the present application is to provide a biological fluidized bed immobilized microorganism wastewater treatment device and method, so as to overcome the shortcomings of the prior art, and creatively combine the biological fluidized bed with the immobilized microorganism technology to enable the microorganisms to stably adhere to the carrier, thereby not only improving the utilization rate of the microorganisms, but also enhancing the resistance of the microorganisms to harsh environments. The biological fluidized bed enables the microorganism carrier particles to be in a fluidized state in the fluid, increases the contact area between the microorganisms and the substrate, and thus improves the mass transfer efficiency.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] On the one hand, the present application provides a biological fluidized bed immobilized microorganism wastewater treatment device, which is a tank structure, and a biological reaction zone is arranged in the tank. The biological reaction zone includes a fixed plate and an embedding small ball. The fixed plate includes a first fixed plate and a second fixed plate, and the embedding small ball is arranged between the first fixed plate and the second fixed plate. The embedding small ball is composed of polyvinyl alcohol, sodium alginate, nano-modified biochar, and antibiotic degrading bacteria.

[0007] In some other embodiments, the fixed plate is a porous circular plate, and the pore size of the porous circular plate is smaller than the embedding beads;

[0008] Alternatively, the biological reaction zone further comprises a support column, which is vertically connected with the first fixed plate and the second fixed plate respectively.

[0009] In some other embodiments, the carrier precipitation zone is further included, which is arranged in the tank body and below the biological reaction zone; the carrier precipitation zone is a circular truncated cone structure, and the bottom of the carrier precipitation zone is provided with a sludge discharge valve.

[0010] In some other embodiments, the pipeline system is further included, which is arranged on the side wall of the tank body; the pipeline system comprises, from top to bottom, a water outlet pipe, a reflux pipe, a water inlet pipe and an aeration pipe arranged on the side wall of the tank body in sequence; the water outlet pipe is arranged above the biological reaction zone, and the reflux pipe, the water inlet pipe and the aeration pipe are arranged between the biological reaction zones; the water outlet pipe and the aeration pipe are arranged at the top and the bottom of the same side wall respectively; the reflux pipe and the water inlet pipe are arranged on the same side wall respectively; and the water inlet pipe and the aeration pipe are arranged oppositely.

[0011] In some other embodiments, the water inlet pipe is sequentially provided with a water inlet pump, a valve and a flow meter; the reflux pipe comprises, in sequence, a reflux water outlet, a valve, a flow meter, a reflux pump and a reflux water inlet, the reflux water outlet is arranged above the reflux water inlet, and the reflux water inlet is arranged above the water inlet pipe.

[0012] Alternatively, the aeration pipe is connected with a vortex air pump.

[0013] In some other embodiments, the exhaust valve, the cover plate, the bracket, the heating rod and the thermal insulation cotton are further included; the cover plate is arranged on the top of the tank body, and the exhaust valve is arranged on the cover plate; the bracket is arranged on the bottom of the tank body, the heating rod is arranged on the inner wall of the tank body, and the thermal insulation cotton is arranged on the outer wall of the tank body.

[0014] In some other embodiments, the particle size of the nano-modified biochar in the embedding beads is less than 100 nm, and the embedding rate of the antibiotic-degrading bacteria is more than 85%.

[0015] In some other embodiments, the preparation method of the embedding beads comprises the following steps:

[0016] (1) rejuvenating the antibiotic-degrading bacteria in the culture medium to prepare an antibiotic-degrading bacteria suspension;

[0017] (2) The corn stalks were calcined under an inert gas to obtain biochar; the biochar was treated and ground at a low temperature and then mixed with deionized water, and then centrifuged and dried to make nano-biochar particles.

[0018] (3) After mixing and culturing the nano-biochar particles with antibiotic-degrading bacterial suspension and allowing them to stand, a composite embedded microsphere core-bacterial suspension mixture I was obtained.

[0019] (4) Mix polyvinyl alcohol and sodium alginate solution to prepare mixture II;

[0020] (5) Mix bacterial solution I with solution II to prepare bacterial solution III;

[0021] (6) Add CaCl2 aqueous solution to bacterial culture mixture III to carry out cross-linking reaction, and then the embedded microspheres are obtained.

[0022] In some other embodiments, in step (2), the calcination temperature is 400-600℃, and the calcination time is 2-8 hours;

[0023] The low-temperature treatment is performed at a temperature of -75 to -85°C for 20-30 hours.

[0024] The centrifugation is performed at a speed of 9000-10000 rpm for 15-30 minutes.

[0025] In step (3), the mass ratio of the nano-biochar particles to the antibiotic-degrading bacterial suspension is 1:(3-6);

[0026] In step (4), the polyvinyl alcohol in the mixture II has a molecular weight of 72000-78000 Da, a viscosity of 12.0-16.0 mPa·s, a content of 5.0-10.0 wt.%, and a sodium alginate content of 1.0-5.0 wt.%.

[0027] In step (5), the volume ratio of the bacterial solution mixture I to the mixture II is 1:1 to 1:3;

[0028] In step (6), the content of CaCl2 is 3.0-5.0 wt.%, and the crosslinking time is 6-8 h.

[0029] On the other hand, the present invention provides a biological fluidized bed immobilized microbial wastewater treatment method, wherein the wastewater to be treated is sent to the biological fluidized bed immobilized microbial wastewater treatment device described in the first aspect for treatment;

[0030] Preferably, the wastewater is antibiotic-containing wastewater; more preferably, the wastewater is meropenem-containing wastewater.

[0031] The beneficial effects of this invention are:

[0032] (1) This invention creatively combines biological fluidized bed with immobilized microbial technology to improve the removal efficiency of pollutants in organic wastewater, especially for pollutants containing antibiotics; wherein, microorganisms can be stably attached to the carrier, which not only improves the survival and reproduction of microorganisms, but also enhances their resistance to harsh environments; the biological fluidized bed makes the microbial carrier particles fluidized in the fluid, increasing the contact area between microorganisms and substrates, thereby improving mass transfer efficiency.

[0033] (2) The immobilized microbial carrier material of this invention is composed of nano-modified biochar, sodium alginate, polyvinyl alcohol and other materials, which fixes the microorganisms in a specific space, maintains their activity and can be reused. It can effectively promote the growth and reproduction of microorganisms in water, ensure their effective colonization in water, and further improve the self-purification capacity of water by reconstructing the micro-ecosystem of water. Compared with traditional biofilm fluidized beds, the immobilized microbial carrier is confined under the fixed plate, which facilitates the centralized treatment and discharge of water samples. It can realize the orderly flow of water for a long time, which facilitates the circulation of immobilized embedded microbial balls in a limited space, thereby promoting the growth of microorganisms in the bioreactor, and thus greatly enhancing the water treatment capacity and making it less prone to clogging.

[0034] (3) By changing the inlet and aeration angles, the present invention makes the fluidization more uniform and the water flow in the reactor more stable, reducing hydraulic loss and changing the shape of the reactor wall to reduce the wear of the carrier and the reactor wall, thereby effectively increasing the life of the immobilized balls. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 The colony morphology of the R51 strain recovered from the embedded microspheres in Example 3 of this invention on LB medium;

[0037] Figure 2 The image shows the microscopic morphology of the R51 strain recovered from the embedded microspheres in Example 3 of this invention.

[0038] Figure 3 The content of meropenem antibiotic under different treatment conditions in Example 3 of the present invention;

[0039] Figure 4 The degradation rate of meropenem antibiotic under different treatment conditions in Example 3 of this invention;

[0040] Figure 5In Example 3 of this invention, the biomass of the antibiotic-degrading microorganism R51 strain in the wastewater is shown.

[0041] Figure 6 This is a schematic diagram of the system for treating antibiotic wastewater using a combined airlift fluidized bed and bioreactor as described in Embodiment 1 of the present invention.

[0042] Figure 7 This is a left view of the system for treating antibiotic wastewater using an airlift fluidized bed-bioreactor combination in Embodiment 1 of the present invention;

[0043] Figure 8 This is a cross-sectional view (AA) of the system for treating antibiotic wastewater using an airlift fluidized bed-bioreactor combination in Embodiment 1 of the present invention.

[0044] The components include: 1. Tank body; 2. Inlet pipe; 3. Outlet pipe; 4. Return pipe; 5. Aeration pipe; 6. Inlet pump; 7. Valve; 8. Meter; 9. Return pump; 10. Vortex air pump; 11. Fixing plate; 12. Support column; 13. Embedded ball; 14. Exhaust valve; 15. Cover plate; 16. Bracket; 17. Heating rod; 18. Insulation cotton; 19. Sludge discharge valve. Detailed Implementation

[0045] In the specific embodiments of the present invention, the antibiotic-degrading bacterium used is strain R51 (Pseudomonas putida), which is the strain R51 disclosed by Chuanqing Zhong et al. in Cadmium stress efficiently enhanced meropenem degradation by the meropenem-and cadmium-resistant strain Pseudomonas putidaR51, Journal of Hazardous Materials, 429(2022)128354:1-4.

[0046] The culture medium used for strain R51 was LB medium: 10.0g sodium chloride, 10.0g tryptone, 5.0g yeast extract, and deionized water to a final volume of 1L, with the pH adjusted to 7.0.

[0047] Unless otherwise specified, all other raw materials are commercially available standard products.

[0048] The present invention will now be described in further detail with reference to the accompanying drawings.

[0049] Example 1

[0050] A biological fluidized bed immobilized microbial wastewater treatment device, such as Figures 6-7As shown, it includes: a tank body 1, a piping system, a bioreactor zone, a carrier sedimentation zone, and a base support 16. The tank body 1 is cylindrical with a total height of 500mm; the top of the tank body 1 is equipped with an exhaust valve 14 and a cover plate 15. The exhaust valve 14 has a diameter of 20mm and is used to discharge excess gas; the cover plate 15 is used to seal the tank body 1.

[0051] The bottom of the tank 1 is provided with a support 16, which is a three-legged support used to support the tank 1 and increase the stability of the support. The inner wall of the tank 1 is provided with a heating rod 17, and the outer wall of the tank 1 is provided with heat insulation cotton 18. The heating rod 17 and heat insulation cotton 18 are used to ensure the optimal temperature for the growth of microorganisms inside the tank 1.

[0052] The tank 1 is arranged from top to bottom as a bioreactor zone and a carrier sedimentation zone. The bioreactor zone is located 100 mm below the top of the tank 1 and includes a fixing plate 11, a support column 12, and embedded microspheres 13.

[0053] The fixing plate 11 includes a first fixing plate and a second fixing plate, which are respectively disposed at the top and bottom of the bioreactor zone, with a distance of 480 mm between them. The space formed between the first and second fixing plates is used to place the embedded microspheres 13. The fixing plate 11 is a circular plate, which is a porous circular plate with pores smaller than the embedded microspheres 13. Wastewater can flow through the pores in the circular plate, while the embedded microspheres 13 remain in the middle and circulate continuously, decomposing the organic matter in the wastewater. The diameter of the circular plate is the same as the diameter of the tank 1, and the thickness of the circular plate is 10 mm. The fixing plate 11 is used to block and settle the embedded microspheres 13.

[0054] The support column is a circular column, and the upper and lower ends of the support column 12 are threaded. The support column 12 is disposed between the first fixing plate and the second fixing plate. The support column 12 is connected to the first fixing plate and the second fixing plate respectively by the thread. The support column 12 is a solid column with a diameter of 80mm. The support column 12 is used to support the fixing plate 11, thereby increasing the stability of the fixing plate 11.

[0055] The carrier sedimentation zone is connected to the bioreactor zone. The carrier sedimentation zone has a frustum structure. A sludge discharge valve 19 is provided at the bottom of the carrier sedimentation zone. The diameter of the sludge discharge valve 19 is the same as the diameter of the bottom of the carrier sedimentation zone. The height of the carrier sedimentation zone is 100 mm and the bottom diameter is 30 mm.

[0056] The piping system described above is installed on the side wall of the tank 1. The piping system includes, from top to bottom, an outlet pipe 3, a return pipe 4, an inlet pipe 2, and an aeration pipe 5 installed on the side wall of the tank 1. The outlet pipe 3 is located above the biological reaction zone, while the return pipe 4, inlet pipe 2, and aeration pipe 5 are located between the biological reaction zones. The outlet pipe 3 and aeration pipe 5 are located at the top and bottom of the same side wall, respectively. The return pipe 4 and inlet pipe 2 are located on the same side wall, respectively. The inlet pipe 2 and aeration pipe 5 are arranged opposite each other. Figure 7 As shown, the piping system is installed at four locations on the outer wall of tank 1. The outlet pipe 3 and return pipe 4 are arranged at 90° angles to the outer wall of tank 1 in opposite left-right directions at the top and middle of tank 1, respectively. The inlet pipe 2 and aeration pipe 5 are arranged at 180° angles to the outer wall of tank 1 in opposite front-back directions at the lower part of tank 1, and are horizontal to the outlet pipe 3 and return pipe 4. Specifically:

[0057] The inlet pipe 2 is located at the bottom of the side wall of the tank 1 and above the second fixing plate. The distance between the inlet pipe 2 and the second fixing plate is 80mm. The diameter of the inlet pipe 2 is 20mm. The inlet pipe 2 is equipped with an inlet pump 6, a valve and a meter in sequence. The inlet pipe 2 is used to input the sewage to be treated into the tank 1.

[0058] The water outlet pipe 3 is located at the top of the other side wall of the tank 1, and a water outlet valve is provided on the water outlet pipe 3; the water outlet pipe 3 is located 50mm from the top of the tank and has a diameter of 20mm; the water outlet pipe 3 is used to discharge treated wastewater.

[0059] The return pipe 4 is installed on the side wall of the tank 1 and located between the first fixed plate and the second fixed plate. The return pipe 4 includes a return outlet and a return inlet. The return outlet is located on the side wall of the tank 1. The return outlet of the return pipe 4 is opposite to the outlet pipe 3 and is located at the lower part of the outlet pipe 3. The return outlet of the return pipe 4 is located 160mm below the outlet pipe 3. The return inlet of the return pipe 4 is located at the upper part of the inlet pipe 2. A valve 7, a meter 8, and a return pump 9 are sequentially installed on the return pipe 4. The diameter of the return pipe 4 is 20mm, and the distance between the return outlet and the return inlet of the return pipe 4 is 280mm. The return pipe 4 is used to circulate sewage back within the tank 1.

[0060] The aeration pipe 5 is located at the bottom of the other side wall of the tank 1 and at the upper end of the second fixed plate. The distance between the aeration pipe 5 and the second fixed plate is 60mm. The aeration pipe 5 is connected to the vortex air pump 10. The aeration pipe 5 is arranged opposite to the water inlet pipe 2 and is located at the lower part of the water inlet pipe 2. The aeration pipe 5 is used to fill the tank 1 with air, so as to achieve full mixing of air and sewage, and at the same time increase the dissolved oxygen content in the water to meet the needs of microbial growth and metabolism, thereby improving sewage treatment efficiency.

[0061] The working process of the biological fluidized bed immobilized microbial wastewater treatment device is as follows:

[0062] Wastewater to be treated is fed into tank 1 through inlet pipe 2. Simultaneously, vortex air pump 10 introduces air into tank 1 through aeration pipe 5. Due to the propulsion of the gas and the guiding effect of the reactor wall, the water flow forms an upward spiral fluidization phenomenon. At the same time, the immobilized carrier flows with the water, increasing the contact area between the immobilized microorganisms and the water, thereby increasing the reaction rate. In addition, the water flow is circulated through the external return pipe 4, which also facilitates the flow of the water. After internal circulation and external circulation, most of the organic matter is degraded in the reactor. The water flows out from the upper drain pipe 3, and excess gas escapes from the top exhaust valve 14. The immobilized carrier in tank 1 is blocked in the middle reaction zone by the fixing plate 11. After the carrier breaks down or the water flow impact decreases, it settles at the bottom of the tank through the lower fixing plate and is discharged through the sludge discharge valve 9.

[0063] Example 2

[0064] The preparation method of the embedded microspheres in the bioreactor zone in Example 1 includes the following steps:

[0065] (1) Rejuvenation of antibiotic-degrading bacteria R51

[0066] The antibiotic-degrading bacteria R51 selected in the laboratory was added to LB medium (10.0 g sodium chloride, 10.0 g tryptone, 5.0 g yeast extract, deionized water to a final volume of 1 L, pH adjusted to 7.0, dispensed into Erlenmeyer flasks, sterilized at 121℃ for 20 min, and cooled for later use). The culture was carried out at 30℃ and 150 r / min on a shaker for 24 h until the logarithmic growth phase was reached. The bacterial suspension was then centrifuged for 10 min (6000 r / min), and the bacterial cells were washed three times with physiological saline and then added back to physiological saline to prepare a bacterial suspension for subsequent studies.

[0067] (2) Preparation of nano-modified biochar

[0068] ① Preparation of biochar:

[0069] Biochar was prepared using corn stalks as the raw material. Corn stalks were obtained from farmers, cleaned, and dried. They were then dried to constant weight in a 105℃ forced-air dryer, cut into 1-2cm pieces, and pulverized to a particle size of less than 2mm. The pulverized corn stalk powder was weighed, placed in a ceramic crucible, sealed with aluminum foil, and then placed in a muffle furnace for pyrolysis at 500℃ under nitrogen for 2 hours to prepare biochar. The biochar was then passed through a 100-mesh sieve to remove large particles and stored for later use.

[0070] ②Preparation of nano-biochar:

[0071] The obtained biochar was frozen at -80℃ for 24 hours and then ground at 350 r / min for 2 hours using a ball mill (the diameter of the grinding balls was 3, 5 and 8 mm, and the ball-to-powder ratio was 20:1) to obtain ball-milled biochar.

[0072] After mixing ball-milled biochar with deionized water in a 500 mL beaker, the mixture was sonicated for 60 min using a probe-type cell disruptor, then stirred thoroughly for 10 min, and centrifuged at 9500 r / min for 20 min at 25 °C to obtain a nano-biochar suspension. The suspension was then dried at 105 °C to obtain nano-biochar particles.

[0073] (3) The prepared R51 bacterial suspension and nano-biochar were mixed in an Erlenmeyer flask at a ratio of 0.005 g / mL. After shaking gently, the mixture was left to stand at room temperature for 1 hour to obtain the composite embedded microsphere core-bacterial solution I.

[0074] (4) Polyvinyl alcohol (PVA) with a molecular weight of 75000 Da and a viscosity of 15.0 mPa·s and sodium alginate (SA) were dissolved in a 90°C water bath shaker and a 60°C water bath, respectively. After dissolution, the two were further dissolved and mixed in a 60°C water bath shaker. After the mixture was uniform, the shaking was stopped and the mixture was cooled to room temperature to obtain mixture II. The content of PVA in mixture II was 8.0 wt% and the content of SA was 2.0 wt%.

[0075] (5) Mix equal volumes of bacterial solution I and bacterial solution II to obtain bacterial solution III;

[0076] (6) Using a disposable syringe, inject bacterial suspension mixture III into a CaCl2 aqueous solution, crosslink for 6 hours, and then place in a refrigerator to solidify, forming spherical MEM-R51 embedded microspheres. Rinse three times with physiological saline for later use. The CaCl2 content is 4.0 wt%.

[0077] The performance of the prepared embedded microspheres was tested, and the test methods and results are shown in Table 1 below.

[0078] Diameter measurement: The diameter of the prepared embedded microspheres was measured using vernier calipers, and the average value was calculated for 30 microspheres.

[0079] Mechanical strength test: Prepare inorganic salt basal culture medium, and take 5 mL of phosphate buffer (KH2PO4 8.5 g·L⁻¹) respectively. -1 K2HPO4·H2O 21.75g·L -1 Na₂HPO₄·12H₂O 33.4 g·L⁻¹ -1 NH4Cl 5.0 g·L -1 ); 3 mL MgSO4 aqueous solution (22.5 g·L⁻¹) -1 ); 1 mL CaCl2 aqueous solution (36.4 g·L⁻¹) -1 ); 1 mL FeCl3 aqueous solution (0.25 g·L⁻¹) -1 ); 1 mL of trace elements (MnSO4·H2O 39.9 mg·L) -1 ZnSO4·H2O 42.8 mg·L -1 (NH4)6Mo7O 24 ·4H2O 34.7mg·L -1 The volume was adjusted to 1L, and the pH of the culture medium was adjusted to 6.8–7.0. All glassware and solutions used in this experiment were autoclaved at 121°C for 30 minutes before use. Under aseptic conditions, the immobilized microspheres were immersed in the sterilized and cooled culture medium, sealed, and placed on a shaker for shaking. The degree of microsphere breakage was observed after 10 days.

[0080] Expansion coefficient detection: The diameter of the immobilized microspheres was measured after shaking in an inorganic salt culture medium for 10 days. The ratio of the measured average diameter to the original microsphere diameter is the expansion coefficient.

[0081] Mass transfer performance testing: Prepare a 2% methylene blue ethanol solution (freshly prepared and used immediately). Add 30 drops to 500 mL of distilled water, mix thoroughly, and then use this solution to determine the mass transfer performance of the immobilized microspheres. Add 50 immobilized microspheres to this solution and shake on a shaker. After 24 hours, measure the absorbance of the methylene blue solution with the microspheres and the original methylene blue solution at a wavelength of 665 nm. Compare the measured absorbance values; the change in absorbance value indirectly reflects the mass transfer performance of the immobilized microspheres.

[0082] Cell embedding rate detection: The embedding rate was estimated using colony counting. Before embedding, the bacterial suspension was diluted and spread on LB agar medium for colony counting. After embedding, 30 embedded microspheres were taken, rinsed with physiological saline to release the unembedded cells, and the rinsing solution was diluted and spread again for colony counting. The colony counts before and after embedding were compared to calculate the cell embedding rate.

[0083] Table 1 Performance parameters of the embedded microspheres

[0084] Diameter (mm) Swelling coefficient (%) Mechanical strength (MPa) Mass transfer performance (%) Specific embedding rate (%) 4.5 5.9 100 85.12 86.36

[0085] In this embodiment, the composition of the embedded microspheres was also studied. The study found that the embedded microspheres prepared by this invention use polyvinyl alcohol (PVA) as the main raw material. PVA has high viscosity, is easy to mold, and does not have a toxic effect on microorganisms. Combining PVA with sodium alginate (SA) can greatly improve the molding effect. The nano-modified biochar has large pores, providing more attachment area for microorganisms, increasing the specific surface area, and adding new functional groups. It also improves the biocompatibility and hydrophilicity of the biofiller surface, thereby increasing the proliferation rate and adhesion degree of microorganisms, and also promoting their activity. The microorganism is the antibiotic-degrading bacterium R51 (Pseudomonas putida), specifically the strain R51 disclosed by Chuanqing Zhong et al. in "Cadmium stress efficiently enhanced meropenem degradation by the meropenem-and cadmium-resistant strain Pseudomonas putidaR51, Journal of Hazardous Materials, 429(2022)128354:1-4". This method can increase the survival and retention time of microorganism R51 in water, thereby better improving the degradation effect of antibiotics in water.

[0086] Example 3

[0087] The apparatus for treating antibiotic wastewater using biological fluidized bed immobilized microorganisms as described in Example 1 and the encapsulated microspheres prepared in Example 2 were used to treat penem antibiotic wastewater. The treatment process is as follows:

[0088] After encapsulating R51 bacterial suspension with materials such as nano-biochar, the upper fixing plate of the reactor was opened, and microbial encapsulated pellets were added into the tank at a dosage of 40% of the effective volume of the reactor tank. The ball valve of the inlet pipe was opened to control the inlet flow rate, and wastewater containing meropenem (10 mg / L) was added to the reactor. The return pipe was opened, and the return flow rate was controlled to allow the water to circulate in the return pipe. Air was introduced into the reactor tank through the aeration pipe for aeration, and the aeration intensity was controlled to keep the carrier in a suspended state, forming a fluidized bed. After aeration and cultivation, the aeration intensity was reduced to allow the carrier to settle. The carrier was observed, and stable and continuous aeration was maintained when the carrier was in a slightly swaying state.

[0089] After adding the encapsulated microspheres for 24 hours, water samples were collected from the effluent every 12 hours to test the antibiotic concentration. The results showed that the system achieved a 92.4% removal rate of meropenem after 72 hours. Images of R51 plates and bacterial cells are shown below. Figure 1 And as shown in Figure 2. From Figure 1 It can be seen that the colonies of strain R51 are small, round in shape, with smooth edges, and are white and opaque. From... Figure 2 As can be seen, R51 bacteria are rod-shaped and are Gram-negative.

[0090] In this embodiment, the removal rate of meropenem under various treatment conditions was studied, and the results are as follows: Figure 3 , 4 As shown in the figure. Among them, MEM wastewater is wastewater containing 10 mg / L meropenem without the addition of R51 bacterial agent, serving as a control; MEM wastewater-R51 is wastewater containing 10 mg / L meropenem with R51 bacterial solution added, the amount of bacterial solution being the same as the amount of bacterial solution required for the encapsulated microspheres; MEM wastewater-R51 encapsulated microspheres is wastewater containing 10 mg / L meropenem treated with R51 encapsulated microspheres; MEM wastewater-R51 encapsulated microspheres-airlift reactor is wastewater containing 10 mg / L meropenem treated with R51 encapsulated microspheres in conjunction with an airlift reactor.

[0091] from Figure 3 , 4 It can be seen that the degradation rate of meropenem using the reactor of this invention in combination with R51-embedded microspheres is significantly higher than that of R51-embedded microspheres and R51 free bacteria. It is speculated that the immobilized carrier may provide growth and attachment sites for microorganisms, while also enabling cells to maintain higher activity.

[0092] In this embodiment, the biomass of the degrading microorganism R51 strain in the water sample was studied, and the results are as follows: Figure 5 As shown. From Figure 5 It can be seen that, except for the control group (MEM-R51), the R51 microbial strains in both the MEM-R51 embedded microsphere-airlift reactor and MEM-R51 embedded microsphere treatment methods can proliferate with the extension of treatment time. However, with further extension of treatment time, especially when the treatment time exceeds 48 hours, the difference in the number of R51 microorganisms between the two treatment methods becomes larger. This indicates that the embedding substrate not only provides a good living environment for microorganisms but also effectively promotes microbial reproduction, thereby ensuring the degradation effect of meropenem. In addition, the airlift reactor of this invention can promote the flow of water and embedded microspheres, increase the contact area between the microspheres and wastewater, and improve the removal efficiency.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for treating wastewater using immobilized microbial fluidized bed technology, characterized in that, The wastewater to be treated is sent to a biological fluidized bed immobilized microbial wastewater treatment device for treatment; the wastewater contains the antibiotic meropenem. The biological fluidized bed immobilized microbial wastewater treatment device has a tank structure, characterized in that a biological reaction zone is provided inside the tank; the biological reaction zone includes a fixing plate and embedded spheres, the fixing plate includes a first fixing plate and a second fixing plate, and the embedded spheres are disposed between the first fixing plate and the second fixing plate; the embedded spheres are composed of polyvinyl alcohol, sodium alginate, nano-modified biochar and antibiotic-degrading bacteria; The fixing plate is a porous circular plate, and the diameter of the holes in the porous circular plate is smaller than that of the embedded small ball; The device also includes a piping system, which comprises an outlet pipe, a return pipe, an inlet pipe, and an aeration pipe arranged sequentially from top to bottom on the side wall of the tank; the inlet pipe and the aeration pipe are arranged opposite to each other. The aeration pipe is connected to the vortex air pump; The particle size of the nano-modified biochar in the embedded microspheres is less than 100 nm. The piping system is installed on the side wall of the tank; the outlet pipe is installed above the biological reaction zone, and the return pipe, inlet pipe and aeration pipe are installed between the biological reaction zones; the outlet pipe and aeration pipe are respectively installed at the top and bottom of the same side wall; the return pipe and inlet pipe are respectively installed on the same side wall.

2. The biological fluidized bed immobilized microbial wastewater treatment method as described in claim 1, characterized in that, The bioreactor zone also includes support columns, which are vertically connected to the first fixing plate and the second fixing plate, respectively.

3. The biological fluidized bed immobilized microbial wastewater treatment method as described in claim 1, characterized in that, It also includes a carrier sedimentation zone, which is located inside the tank and below the bioreactor zone; The carrier sedimentation zone has a frustum structure, and a sludge discharge valve is provided at the bottom of the carrier sedimentation zone.

4. The biological fluidized bed immobilized microbial wastewater treatment method as described in claim 1, characterized in that, The inlet pipe is equipped with an inlet pump, a valve, and a flow meter in sequence; the return pipe includes a return outlet, a valve, a flow meter, a return pump, and a return inlet connected in sequence, with the return outlet located above the return inlet and the return inlet located above the inlet pipe.

5. The biological fluidized bed immobilized microbial wastewater treatment method as described in claim 1, characterized in that, It also includes an exhaust valve, a cover plate, a bracket, a heating rod, and insulation cotton; the cover plate is located at the top of the tank, and the exhaust valve is located on the cover plate; the bracket is located at the bottom of the tank, the heating rod is located on the inner wall of the tank, and the insulation cotton is located on the outer wall of the tank.

6. The biological fluidized bed immobilized microbial wastewater treatment method as described in claim 1, characterized in that, The encapsulation rate of the antibiotic-degrading bacteria is above 85%.

7. The biological fluidized bed immobilized microbial wastewater treatment method as described in claim 1, characterized in that, The method for preparing the embedded microspheres includes the following steps: (1) The antibiotic-degrading bacteria were revitalized in the culture medium to prepare an antibiotic-degrading bacterial suspension; (2) The corn stalks were calcined under an inert gas to obtain biochar; the biochar was treated and ground at a low temperature and then mixed with deionized water, and then centrifuged and dried to make nano-modified biochar particles; (3) After mixing and culturing the nano-modified biochar particles with antibiotic-degrading bacterial suspension and allowing them to stand, a composite embedded microsphere core-bacterial suspension mixture I was obtained. (4) Mix polyvinyl alcohol and sodium alginate solution to prepare mixture II; (5) Mix bacterial solution I with solution II to prepare bacterial solution III; (6) Add CaCl2 aqueous solution to bacterial culture mixture III to carry out cross-linking reaction, and then the embedded microspheres are obtained.

8. The biological fluidized bed immobilized microbial wastewater treatment method as described in claim 7, characterized in that, In step (2), the calcination temperature is 400-600 ℃, and the calcination time is 2-8 h; The low-temperature treatment is performed at a temperature of -75 to -85 ℃ for 20-30 hours. The centrifugation is performed at a speed of 9000-10000 rpm for 15-30 minutes. In step (3), the mass ratio of the nano-modified biochar particles to the antibiotic-degrading bacterial suspension is 1:(3-6). In step (4), the polyvinyl alcohol in mixture II has a molecular weight of 72,000-78,000 Da, a viscosity of 12.0-16.0 mPa·s, and a content of 5.0-10.0 wt.%, while the sodium alginate content is 1.0-5.0 wt.%. In step (5), the volume ratio of the bacterial solution mixture I to the mixture II is 1:1 to 1:3; In step (6), the content of CaCl2 is 3.0-5.0 wt.%, and the crosslinking time is 6-8 h.

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