Biological fluidized bed immobilized microorganism wastewater treatment device and method

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a biological fluidized bed immobilized microorganism wastewater treatment device and method, the biological fluidized bed immobilized microorganism wastewater treatment device is of a tank body structure, and a biological reaction area is arranged in a tank body; the biological reaction area comprises fixed plates and embedded balls, the fixed plates comprise a first fixed plate and a second fixed plate, and the embedded balls are arranged between the first fixed plate and the second fixed plate; the embedded pellets are prepared from polyvinyl alcohol, sodium alginate, nano modified charcoal and antibiotic degrading bacteria. A biological fluidized bed is creatively combined with an immobilized microorganism technology, so that microorganisms can be stably attached to a carrier, the utilization rate of the microorganisms is increased, and the resistance of the microorganisms to a severe environment is enhanced; according to the biological fluidized bed, microbial carrier particles are fluidized in fluid, so that the contact area between microorganisms and a substrate is increased, and the mass transfer efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a biological fluidized bed immobilized microbial wastewater treatment device and method. Background Art

[0002] The biological fluidized bed is a technology for treating wastewater using the biofilm method. Oxygenated wastewater passes through a fine filter bed from bottom to top, and uses the filter material covered with biofilm for efficient biological treatment. The biological fluidized bed process overcomes the problems of low microbial content, low biological activity, and unstable treatment effect in the ordinary activated sludge method. At present, the biological fillers of the biological fluidized bed can be divided into inorganic biological fillers, organic biological fillers, and composite biological fillers according to their composition. The biological fillers used in the fluidized bed mainly play the role of fixing the biofilm and providing microorganisms for attachment and growth. However, the existing biological fillers mainly form biofilms on the surface, and the formation and renewal of biofilms are slow and the amount is small.

[0003] Immobilized microbial technology refers to the use of specific methods to fix microorganisms in a specific space to maintain their activity and enable repeated use. This method includes adsorption method, embedding method, etc. Immobilized microbial technology can increase the concentration of microorganisms in the bioreactor, which is beneficial to the separation of solids and liquids after the reaction, thereby reducing the processing time. However, the existing immobilized microorganisms are unevenly distributed in the carrier, the biomass concentration is low and it is easy to form blockages. In addition, during the operation 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, and the diffusion resistance is reduced, resulting in a higher reaction speed during the fluidization process. In addition, wear and tear will occur between the carrier particles and between the carrier and the reactor wall, thereby shortening the life of the immobilized beads. Summary of the invention

[0004] The purpose of the present invention is to provide a biological fluidized bed immobilized microbial wastewater treatment device and method, so as to overcome the shortcomings of the prior art, creatively combine the biological fluidized bed with the immobilized microbial technology to make the microorganisms 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 increases the contact area between the microorganisms and the substrate by fluidizing the microbial carrier particles in the fluid, thereby improving the mass transfer efficiency.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] On the one hand, the present invention provides a biological fluidized bed immobilized microbial wastewater treatment device, which is a tank structure, wherein a biological reaction zone is provided in the tank; the biological reaction zone includes a fixed plate and embedded balls, the fixed plate includes a first fixed plate and a second fixed plate, and the embedded balls are arranged between the first fixed plate and the second fixed plate; the embedded balls are composed of polyvinyl alcohol, sodium alginate, nano-modified biochar and antibiotic-degrading bacteria.

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

[0008] Alternatively, the bioreaction zone further comprises support columns, and the support columns are vertically connected to the first fixing plate and the second fixing plate respectively.

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

[0010] In some other embodiments, it also includes a piping system, which is arranged on the side wall of the tank body; the piping system includes an outlet pipe, a return pipe, a water inlet pipe and an aeration pipe arranged on the side wall of the tank body from top to bottom in sequence; the outlet pipe is arranged above the biological reaction zone, and the return pipe, the water inlet pipe and the aeration pipe are arranged between the biological reaction zones; the outlet pipe and the aeration pipe are respectively on the top and bottom of the same side wall; the return pipe and the water inlet pipe are respectively arranged on the same side wall; the water inlet pipe and the aeration pipe are arranged opposite to each other.

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

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

[0013] In some other embodiments, it also includes an exhaust valve, a cover plate, a bracket, a heating rod and thermal insulation cotton; 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 above 85%.

[0015] In some other embodiments, the method for preparing the embedded beads comprises the following steps:

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

[0017] (2) calcining corn stalks under an inert gas to obtain biochar; treating the biochar at a low temperature, grinding it, mixing it with deionized water, centrifuging it, and drying it to obtain nano biochar particles;

[0018] (3) Mixing the nano-biochar particles with the antibiotic-degrading bacterial suspension and culturing them, and then standing to obtain a composite embedded ball core-bacteria suspension mixture I;

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

[0020] (5) mixing the bacterial solution mixture I with the bacterial solution mixture II to prepare a bacterial solution mixture III;

[0021] (6) Add CaCl2 aqueous solution to the bacterial solution mixture III to carry out a cross-linking reaction to obtain embedded beads.

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

[0023] The temperature of the low temperature treatment is -75 to -85°C and the time is 20 to 30 hours;

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

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

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

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

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

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

[0030] Preferably, the wastewater is wastewater containing antibiotics, and further preferably, the wastewater is wastewater containing meropenem.

[0031] Beneficial effects of the present invention:

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

[0033] (2) The immobilized microbial carrier material of the present invention is composed of nano-modified biochar, sodium alginate, polyvinyl alcohol and other materials, which can fix the microorganisms in a specific space, maintain their activity and be reused, and can effectively promote the growth and reproduction of microorganisms in water bodies, ensure their effective colonization in water bodies, and further improve the self-purification capacity of water bodies by reconstructing the water body micro-ecological system; compared with the traditional biofilm fluidized bed, 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, facilitate the circulation of immobilized embedded microbial pellets in a limited space, thereby promoting the growth of microorganisms in the bioreactor, thereby greatly enhancing the water body treatment capacity and not easy to form blockage;

[0034] (3) The present invention changes the water inlet and aeration angles, and the cyclonic aeration makes the fluidization more uniform, the water flow in the reactor is stable, the hydraulic loss is reduced, and the wear of the carrier and the reactor wall is reduced by changing the shape of the reactor wall, thereby effectively increasing the life of the immobilized beads. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

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

[0037] Figure 2 The bacterial morphology of the R51 strain recovered from the embedded beads in Example 3 of the present invention under a microscope;

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

[0039] Figure 4 is the degradation rate of meropenem antibiotic under different treatment conditions in Example 3 of the present invention;

[0040] Figure 5is the biomass of the R51 strain of antibiotic wastewater-degrading microorganism in Example 3 of the present invention;

[0041] Figure 6 This is a schematic diagram of the structure of the system for treating antibiotic wastewater by combining an airlift fluidized bed and a bioreactor in Example 1 of the present invention;

[0042] Figure 7 It is a left view of the system for treating antibiotic wastewater by combining an airlift fluidized bed and a bioreactor in Example 1 of the present invention;

[0043] Figure 8 It is a cross-sectional view along the AA direction of the system for treating antibiotic wastewater by combining an airlift fluidized bed and a bioreactor in Example 1 of the present invention;

[0044] Among them: tank body 1, water inlet pipe 2, water outlet pipe 3, return pipe 4, aeration pipe 5, water inlet pump 6, valve 7, meter 8, return pump 9, vortex air pump 10, fixing plate 11, support column 12, embedded ball 13, exhaust valve 14, cover plate 15, bracket 16, heating rod 17, insulation cotton 18, mud discharge valve 19 DETAILED DESCRIPTION

[0045] The antibiotic degrading bacteria used in a specific embodiment of the present invention is strain R51 (Pseudomonas putida), which is the strain R51 disclosed by Chuanqing Zhong et al. in Cadmium stress efficiently enhanced meropenem degradation by themeropenem-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: 10.0 g sodium chloride, 10.0 g tryptone, 5.0 g yeast extract, dilute to 1 L with deionized water, and adjust the pH value to 7.0.

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

[0048] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0049] Example 1

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

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

[0052] The bioreaction zone and the carrier precipitation zone are arranged in order from top to bottom in the tank body 1. The bioreaction zone is arranged 100 mm below the top of the tank body 1, and includes a fixing plate 11, a support column 12 and an embedding ball 13.

[0053] The fixing plate 11 includes a first fixing plate and a second fixing plate, which are respectively arranged at the top and the bottom of the biological reaction zone, and the distance between the first fixing plate and the second fixing plate is 480 mm; the space formed between the first fixing plate and the second fixing plate is used to place the embedded small balls 13. The fixing plate 11 is a circular plate, and the circular plate is a porous circular plate, and the aperture of the porous circular plate is smaller than the embedded small balls 13; sewage can flow through the aperture in the circular plate, and the embedded small balls 13 stay in the middle and circulate continuously to decompose the organic matter in the sewage. The diameter of the circular plate is the same as the diameter of the tank body 1, and the thickness of the circular plate is 10 mm; the fixing plate 11 is used to block and settle the embedded small balls 13.

[0054] The support column is a circular column, and threads are provided at the upper and lower ends of the support column 12. The support column 12 is arranged 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 threads. The support column 12 is a solid column with a diameter of 80 mm. 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 area is connected to the biological reaction area, and the carrier sedimentation area has a truncated cone structure. A mud discharge valve 19 is provided at the bottom of the carrier sedimentation area, and the diameter of the mud discharge valve 19 is the same as the diameter of the bottom of the carrier sedimentation area; the height of the carrier sedimentation area is 100 mm, and the bottom diameter is 30 mm.

[0056] The pipeline system is arranged on the side wall of the tank body 1; the pipeline system includes a water outlet pipe 3, a return pipe 4, a water inlet pipe 2 and an aeration pipe 5 arranged on the side wall of the tank body 1 from top to bottom; the water outlet pipe 3 is arranged above the biological reaction zone, and the return pipe 4, the water inlet pipe 2 and the aeration pipe 5 are arranged between the biological reaction zones; the water outlet pipe 3 and the aeration pipe 5 are respectively arranged on the top and bottom of the same side wall; the return pipe 4 and the water inlet pipe 2 are respectively arranged on the same side wall; the water inlet pipe 2 and the aeration pipe 5 are arranged opposite to each other. Figure 7 As shown, the pipeline system is respectively arranged at four positions of the outer wall of the tank body 1, wherein the water outlet pipe 3 and the return pipe 4 are respectively arranged at the top and the middle of the tank body 1 in opposite directions at 90 degrees to the outer wall of the tank body 1; the water inlet pipe 2 and the aeration pipe 5 are respectively arranged at the lower part of the tank body 1 in opposite directions at 180 degrees to the outer wall of the tank body 1 and in a horizontal direction with the water outlet pipe 3 and the return pipe 4. Specifically:

[0057] The water inlet pipe 2 is arranged at the bottom of the side wall of the tank body 1 and on the upper part of the second fixed plate, and the distance between the water inlet pipe 2 and the second fixed plate is 80 mm; the water inlet pipe 2 has a diameter of 20 mm; the water inlet pump 6, a valve and a meter are arranged on the water inlet pipe 2 in sequence; the water inlet pipe 2 is used to input the sewage to be treated into the tank body 1.

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

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

[0060] The aeration pipe 5 is arranged at the bottom of the other side wall of the tank body 1 and at the upper end of the second fixed plate. The distance between the aeration pipe 5 and the second fixed plate is 60 mm. 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 the aeration pipe 5 is arranged at the lower part of the water inlet pipe 2. The aeration pipe 5 is used to fill air into the tank body 1 to achieve sufficient stirring and mixing of air and sewage, and at the same time provide an increase in the dissolved oxygen content in the water to meet the needs of microbial growth and metabolism, thereby improving the sewage treatment efficiency.

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

[0062] The sewage to be treated is input into the tank body 1 through the water inlet pipe 2, and the vortex air pump 10 simultaneously introduces air into the tank body 1 through the aeration pipe 5. Due to the push of the gas and the guiding effect of the reactor wall, the water flow forms a spiral upward fluidization phenomenon from bottom to top. At the same time, the immobilized carrier flows with the water, which increases the contact area between the immobilized microorganism and the water body, thereby increasing the reaction speed. In addition, the water flow circulates through the external return pipe 4, which is also conducive to the flow of the water body. After internal circulation and external circulation, most of the organic matter is degraded in the reactor, the water flow is discharged from the upper drain pipe 3, and the excess gas escapes from the top exhaust valve 14. The immobilized carrier in the tank body 1 is blocked in the middle reaction zone by the fixed plate 11. After the carrier is broken or the water flow impact is reduced, it is precipitated at the bottom of the pool through the lower fixed plate and discharged through the mud valve 9.

[0063] Example 2

[0064] The method for preparing the embedded beads in the bioreaction zone in Example 1 comprises the following steps:

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

[0066] The antibiotic-degrading bacteria R51 screened in the laboratory were added to LB medium (10.0 g of sodium chloride, 10.0 g of tryptone, 5.0 g of yeast extract, made up to 1 L with deionized water, adjusted to pH 7.0, dispensed into Erlenmeyer flasks, sterilized at 121°C for 20 min, and cooled for use), cultured in a shaking incubator at 30°C, 150 r / min for 24 h until the logarithmic growth phase, and then centrifuged for 10 min (6000 r / min). The bacteria were washed three times with saline and re-added to saline to make a bacterial suspension for subsequent studies.

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

[0068] ① Preparation of biochar:

[0069] Corn stalks were selected as raw materials for preparing biochar. Corn stalks were obtained from farmers in the fields, cleaned, dried, and placed in a 105°C forced air dryer to constant weight, cut into small pieces of 1-2 cm, and crushed with a grinder to a particle size of less than 2 mm. The crushed corn stalk powder was weighed, placed in a ceramic crucible, sealed with aluminum foil, and placed in a muffle furnace for pyrolysis at 500°C under nitrogen for 2 hours to prepare biochar. It was then sieved through a 100-mesh sieve to remove large particles and keep for later use.

[0070] ② Preparation of Nano-biochar:

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

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

[0073] (3) The prepared R51 bacterial suspension and nano-biochar were mixed in a conical flask at a ratio of 0.005 g / mL, and the mixture was gently shaken and allowed to stand at room temperature for 1 hour to obtain a composite embedded ball core-bacteria liquid mixture I;

[0074] (4) dissolving polyvinyl alcohol (PVA) with a molecular weight of 75000 Da and a viscosity of 15.0 mPa·s and sodium alginate (SA) in a 90° C. water bath oscillator and a 60° C. water bath pot, respectively, and continuing to dissolve and mix the two in a 60° C. water bath oscillator. After being mixed evenly, stopping the oscillation and cooling to room temperature to obtain a mixed solution II, wherein the content of PVA in the mixed solution II is 8.0 wt %, and the content of SA is 2.0 wt %;

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

[0076] (6) Use a disposable syringe to inject the bacterial solution III into the CaCl2 aqueous solution, cross-link for 6 hours, put it in a refrigerator to shape it, make spherical particles MEM-R51 embedded beads, rinse it with physiological saline for 3 times for use. The CaCl2 content is 4.0wt%.

[0077] The prepared embedded beads were subjected to performance tests, and the test methods and results are shown in Table 1 below.

[0078] Diameter measurement: Use a vernier caliper to measure the diameter of the prepared embedded beads, and measure 30 beads to obtain the average value.

[0079] Mechanical strength test: Prepare inorganic salt basal culture medium, take 5mL phosphate buffer (KH2PO48.5 g·L -1 、K2HPO4·H2O 21.75g·L -1 、Na2HPO4·12H2O 33.4g·L -1 、NH4Cl5.0g·L -1 ); 3mL MgSO4 aqueous solution (22.5g·L -1 ); 1 mL CaCl2 aqueous solution (36.4 g·L -1 ); 1 mL FeCl3 aqueous solution (0.25 g·L -1 ); 1mL trace elements (MnSO4·H2O 39.9mg·L -1 、ZnSO4·H2O 42.8mg·L -1 、(NH4)6Mo7O 24 4H2O 34.7mg·L -1 , adjust the volume to 1L, and adjust the pH of the culture medium to 6.8-7.0. The glassware and solutions used in this experiment were sterilized by high pressure steam at 121°C for 30 minutes. Under sterile conditions, the immobilized beads were immersed in the above sterilized and cooled culture medium, sealed, and placed on a shaker for shaking. After 10 days, the degree of breakage of the beads was observed.

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

[0081] Mass transfer performance test: Prepare a 2% methylene blue ethanol solution (prepare and use immediately). Add 30 drops to 500 mL of distilled water, mix well and use for the determination of the mass transfer performance of the beads. Take this solution and add 50 immobilized beads to the shaker. After 24 hours, measure the absorbance of the methylene blue solution with beads and the absorbance of the original methylene blue solution at a wavelength of 665 nm. Compare the measured absorbance values. The change in absorbance value can indirectly reflect the quality of the mass transfer performance of the immobilized beads.

[0082] Bacterial embedding rate detection: The embedding rate is estimated by colony counting method. Before embedding, the bacterial solution is diluted and spread on LB agar medium for colony counting. After embedding, 30 embedded balls are taken and rinsed with physiological saline to release the unembedded bacteria. The rinse solution is diluted and spread for colony counting. Compare the number of colonies before and after embedding to calculate the bacterial embedding rate.

[0083] Table 1 Performance parameters of embedded beads

[0084] Diameter(mm) Expansion 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 beads is also studied. The study found that the embedded beads prepared by the present invention use high molecular polymer-polyvinyl alcohol (PVA) as the main raw material. PVA has a high viscosity, is easier to shape, and does not produce toxic effects on microorganisms. PVA combined with sodium alginate (SA) can greatly improve the molding effect. Nano-modified biochar has larger pores, providing more attachment area for microorganisms, increasing the specific surface area, and also adding new functional groups. At the same time, it improves the biocompatibility and hydrophilicity of the surface of the biological filler, so that the growth rate and adhesion degree of microorganisms are improved, and it also has a certain promoting effect on the activity of microorganisms. The microorganism is used to screen the antibiotic degrading bacteria 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 putida R51, Journal of Hazardous Materials, 429 (2022) 128354: 1-4. This method can increase the survival and retention time of the microorganism R51 in water, and better improve the degradation effect of antibiotics in water.

[0086] Example 3

[0087] The device for treating antibiotic wastewater using immobilized microorganisms in a biological fluidized bed in Example 1 and the embedded beads prepared in Example 2 were used to treat penem antibiotic wastewater. The treatment process was as follows:

[0088] After embedding the R51 bacterial suspension with materials such as nano-biochar, the upper fixed plate of the reactor was opened, and the microorganism-embedded beads were added into the tank body, and the dosage was 40% of the effective volume of the reactor tank body. The ball valve of the water inlet pipe was opened to control the water inlet flow rate, and sewage containing meropenem (10 mg / L) was added into the reactor. The reflux pipe was opened to control the reflux flow rate so that the water flow circulated in the reflux pipe; air was introduced into the reactor tank body through the aeration pipe for aeration, and the aeration intensity was controlled to make the carrier in a suspended state to form a fluidized bed. Aeration culture was performed, and then the aeration intensity was reduced to make the carrier settle down, and the carrier was observed. When the carrier was in a slightly shaking state, aeration was continued stably.

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

[0090] In this example, the removal rate of meropenem under various treatment conditions was studied, and the results are as follows: Figure 3 , 4 As shown. Among them, MEM sewage is sewage containing 10 mg / L meropenem, without R51 bacterial agent, as a control; MEM sewage-R51 is sewage containing 10 mg / L meropenem with R51 bacterial solution added, and the amount of bacterial solution is the same as the amount of bacterial solution required for embedding beads; MEM sewage-R51 embedded beads is the treatment of adding R51 embedded beads to sewage containing 10 mg / L meropenem; MEM sewage-R51 embedded beads-airlift reactor is the integrated treatment of R51 embedded beads combined with airlift reactor in sewage containing 10 mg / L meropenem.

[0091] from Figure 3 , 4 It can be seen that the degradation rate of meropenem by using the reactor of the present invention combined with R51 embedded beads is significantly higher than that of R51 embedded beads and R51 free bacteria. It is speculated that the immobilized carrier may provide growth and attachment points for the growth of microorganisms, while enabling the cells to maintain higher activity.

[0092] In this example, the biomass of the degradation microorganism R51 strain in the water sample was studied, and the results are as follows: Figure 5 As shown. Figure 5 It can be seen that, except for the control group (MEM-R51), the R51 strain of the microorganism in the two treatment methods of MEM-R51 embedded beads-airlift reactor and MEM-R51 embedded beads can proliferate with the extension of the treatment time, but with the further extension of the treatment time, especially when the treatment time is greater than 48h, the difference in the number of microorganisms R51 in the two treatment methods becomes larger. This shows that the embedding matrix not only provides a good living environment for microorganisms, but also effectively promotes the reproduction of microorganisms, thereby ensuring the degradation effect of meropenem. In addition, the airlift reactor of the present invention can promote the flow of water and embedded beads, increase the contact area between the beads and sewage, and improve the removal efficiency.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A biological fluidized bed immobilized microorganism wastewater treatment device, which is a tank structure, characterized in that: A biological reaction zone is provided in the tank body; the biological reaction zone includes a fixed plate and embedded balls, the fixed plate includes a first fixed plate and a second fixed plate, and the embedded balls are arranged between the first fixed plate and the second fixed plate; the embedded balls are composed of polyvinyl alcohol, sodium alginate, nano-modified biochar and antibiotic-degrading bacteria.

2. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 1, characterized in that: The fixing plate is a porous circular plate, and the aperture of the porous circular plate is smaller than the embedded balls; Alternatively, the bioreaction zone further comprises support columns, and the support columns are vertically connected to the first fixing plate and the second fixing plate respectively.

3. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 1, characterized in that: It also includes a carrier sedimentation area, which is arranged in the tank body and below the biological reaction area; the carrier sedimentation area is a truncated cone structure, and a mud discharge valve is provided at the bottom of the carrier sedimentation area.

4. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 1, characterized in that: It also includes a pipeline system, which is arranged on the side wall of the tank body; the pipeline system includes an outlet pipe, a return pipe, a water inlet pipe and an aeration pipe arranged on the side wall of the tank body from top to bottom in sequence; the outlet pipe is arranged above the biological reaction zone, and the return pipe, the water inlet pipe and the aeration pipe are arranged between the biological reaction zones; the outlet pipe and the aeration pipe are respectively on the top and bottom of the same side wall; the return pipe and the water inlet pipe are respectively arranged on the same side wall; the water inlet pipe and the aeration pipe are arranged opposite to each other.

5. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 4, characterized in that: The water inlet pipe is provided with a water inlet pump, a valve and a flow meter in sequence; the reflux pipe comprises a reflux outlet, a valve, a flow meter, a reflux pump and a reflux inlet which are connected in sequence, the reflux outlet is arranged above the reflux inlet, and the reflux inlet is arranged above the water inlet pipe; Alternatively, the aeration pipe is connected to a vortex air pump.

6. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 1, characterized in that: It also includes an exhaust valve, a cover plate, a bracket, a heating rod and thermal insulation cotton; 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.

7. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 1, characterized in that: 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 above 85%.

8. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 1, characterized in that: The method for preparing the embedded beads comprises the following steps: (1) rejuvenating the antibiotic-degrading bacteria in a culture medium to prepare an antibiotic-degrading bacteria suspension; (2) calcining corn stalks under an inert gas to obtain biochar; treating the biochar at a low temperature, grinding it, mixing it with deionized water, centrifuging it, and drying it to obtain nano biochar particles; (3) mixing and culturing the nano-biochar particles with the antibiotic-degrading bacterial suspension, and allowing to stand to obtain a composite embedded ball core-bacteria suspension mixture I; (4) mixing polyvinyl alcohol and sodium alginate solution to prepare mixed solution II; (5) mixing the bacterial solution mixture I with the bacterial solution mixture II to prepare a bacterial solution mixture III; (6) Add CaCl2 aqueous solution to the bacterial solution mixture III to carry out a cross-linking reaction to obtain embedded beads.

9. The biological fluidized bed immobilized microorganism wastewater treatment device according to claim 8, characterized in that: In the step (2), the calcination temperature is 400-600° C. and the calcination time is 2-8 hours; The temperature of the low temperature treatment is -75 to -85°C and the time is 20 to 30 hours; The centrifugation is performed at a speed of 9000-10000 rpm for 15-30 min; In the step (3), the mixing ratio of the nano biochar particles to the antibiotic degrading bacteria suspension is 1:(3-6) by mass; In the step (4), the molecular weight of polyvinyl alcohol in the mixed solution II is 72000-78000Da, the viscosity is 12.0-16.0mPa·s, the content is 5.0-10.0wt.%, and the content of sodium alginate is 1.0-5.0wt.%; In the step (5), the volume ratio of the bacterial solution mixture I to the mixture II is 1:1-1:3; In the step (6), the content of CaCl2 is 3.0-5.0wt.%, and the cross-linking time is 6-8h.

10. A method for treating wastewater using immobilized microorganisms in a biological fluidized bed, characterized in that: Sending the wastewater to be treated to the biological fluidized bed immobilized microorganism wastewater treatment device according to any one of claims 1 to 9 for treatment; Preferably, the wastewater is wastewater containing antibiotics, and further preferably, the wastewater is wastewater containing the antibiotic meropenem.

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