Ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater

Abstract

The invention discloses an ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater, and particularly relates to the technical field of medical wastewater treatment.The ozone-biological coupling degradation process comprises the steps of S1, hydrolytic acidification pretreatment, S2, ozone-biological contact oxidation cooperative treatment, S3, biological filter deep treatment and S4, ultraviolet disinfection. Through hydrolytic acidification, ozone-biological contact oxidation, a biological filter tank, ultraviolet disinfection and other processes, the synergistic effect of ozone and biological treatment is utilized to realize double blocking of antibiotic-resistant genes in medical wastewater in gene and flora levels, the dosage of ozone is reduced, the impact load resistance is high, the operation cost is low, and secondary pollution is avoided.

Description

Technical Field

[0001] This invention relates to the field of medical wastewater treatment technology, and more specifically, to an ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater. Background Technology

[0002] Medical wastewater contains antibiotic residues, high concentrations of organic matter, and a large number of microorganisms, making it an important carrier for the spread of antibiotic resistance genes. These genes can spread from the aquatic environment to the soil, plants, animals, and humans, leading to increased bacterial resistance and posing a serious threat to public health. Therefore, the efficient removal of antibiotic resistance genes from medical wastewater has become a key issue in the field of environmental governance.

[0003] Currently, technologies for treating antibiotic resistance genes in medical wastewater mainly include physicochemical methods (such as ozone oxidation and ultraviolet disinfection) and biological treatment methods (such as activated sludge and biofilm processes). However, each single technology has significant limitations.

[0004] Although ozone oxidation can destroy the nucleic acid structure of antibiotic resistance genes through strong oxidizing properties, it requires a high dosage to achieve the desired effect. This not only results in high operating costs but also easily produces toxic intermediates such as aldehydes and ketones, causing secondary pollution.

[0005] Biological treatment relies on microorganisms to degrade organic matter and antibiotic resistance genes, but it has low efficiency in treating recalcitrant antibiotic residues and complex organic matter, and antibiotic resistance genes may accumulate and spread in the system through microbial metabolism, making it difficult to achieve complete removal.

[0006] While ultraviolet disinfection can inactivate microorganisms, its effect on destroying antibiotic resistance genes in suspension is limited, and it needs to be combined with pretreatment to cope with the impact of high concentrations of pollutants.

[0007] In addition, existing combined processes are mostly simple series connections, which do not form a synergistic mechanism between ozone and biological treatment. This results in insufficient removal rate of antibiotic resistance genes and weak resistance to shock loads, making it difficult to meet the strict control requirements of antibiotic resistance genes in medical wastewater.

[0008] To address the pain points of the existing technology, this invention provides an ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater. Summary of the Invention

[0009] In order to overcome the above-mentioned defects of the prior art, the present invention provides an ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater, so as to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the present invention provides the following technical solution: an ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater, specifically comprising the following steps:

[0011] S1. Hydrolysis and acidification pretreatment: Medical wastewater enters the hydrolysis and acidification tank in an upward flow manner. Under the conditions of hydraulic retention time of 2-3h, pH 6.0-7.5, temperature 15-40℃, and upward flow velocity of 1.0-1.5m / h, macromolecular organic matter is decomposed into small molecule substances.

[0012] S2, Ozone-Biological Contact Oxidation Synergistic Treatment:

[0013] S2.1. The hydrolyzed and acidified effluent is treated with ozone at a concentration of 10-30 mg / L for 30-60 minutes via an ejector to destroy the nucleic acid structure of antibiotic resistance genes.

[0014] S2.2 The effluent treated by ozone is directly introduced into the biological section of the same reaction tank. Under the conditions of hydraulic retention time of 6-8 hours and dissolved oxygen concentration of 2-4 mg / L, the intermediate products are degraded by the elastic three-dimensional packing material loaded with compound bacterial agent.

[0015] S3. Deep treatment using biological filter: Deep treatment is carried out using a biological activated carbon filter with a water flow distributor. The filter media particle size is 2-4mm, and the filtration rate is controlled at 3-5m / h.

[0016] S4. Ultraviolet disinfection, at 30-60 mJ / cm². 2 Radiation dose treatment for 10-30 minutes;

[0017] In this process, steps S2.1 and S2.2 form a synergistic cycle: ozone oxidation improves the biodegradability of organic matter, the biodegradation process reduces ozone consumption, and the compound microbial agent can target and degrade antibiotic resistance genes; the compound microbial agent contains nitrifying bacteria, denitrifying bacteria, and Pseudomonas and / or Bacillus.

[0018] Preferably, the Pseudomonas can secrete extracellular enzymes that can specifically hydrolyze the phosphodiester bonds of antibiotic resistance genes, while Bacillus can enrich antibiotic resistance gene fragments through biosorption.

[0019] Preferably, Pseudomonas and Bacillus are mixed in a ratio of 1:1 to 1:2 and then fixed on an elastic three-dimensional packing material for targeted degradation of antibiotic resistance gene fragments in the ozone-treated biological segment.

[0020] Preferably, the composite bacterial agent in step S2.2 is immobilized by encapsulation with sodium alginate-activated carbon microspheres, and the bacterial agent loading density is ≥10. 5 CFU / g packing material.

[0021] Preferably, in step S4, ultraviolet disinfection uses an ultraviolet lamp with a wavelength of 254 nm to ensure that the formation efficiency of DNA pyrimidine dimers is >90%.

[0022] Preferably, it also includes a system for carrying out the process, the system comprising: connected in sequence:

[0023] The water inlet tank is connected to the hydrolysis acidification tank via a peristaltic pump. The hydrolysis acidification tank is equipped with an upward flow water distribution device and has an internal stirrer for mixing and promoting the hydrolysis acidification reaction.

[0024] The hydrolysis acidification tank is connected to the integrated ozone-biological contact oxidation tank via a valve. The integrated ozone-biological contact oxidation tank includes an ozone section and a biological section. In the ozone section, an ejector is connected to an ozone generator, and an aerator is connected to an aeration pump for ozone addition and distribution. The biological section is filled with elastic three-dimensional packing material loaded with compound microbial agents. The elastic three-dimensional packing material is fixed by an elastic packing material support and is equipped with a mixed liquor return pump for mixed liquor return.

[0025] The integrated ozone-biological contact oxidation tank is connected to a biological filter via a valve. The biological filter contains a water flow distributor, a filter pad, and 2-4 mm diameter biological activated carbon.

[0026] The biological filter is connected to an ultraviolet disinfection device via a valve. The ultraviolet disinfection device is equipped with an ultraviolet lamp assembly, and the radiation dose is regulated by a control system.

[0027] The ultraviolet disinfection device is connected to the water outlet pool;

[0028] It also includes a return pipeline that returns 30-50% of the effluent from the biological section to the ozone section inlet, with valves installed on the pipeline to control the flow rate.

[0029] Preferably, a porous partition is provided between the ozone section and the biological section. The partition has a pore size of ≤5mm, which can ensure the water flow is unobstructed and has a microbial retention rate of ≥95%.

[0030] Preferably, the return pipeline is equipped with a real-time ozone concentration monitor with an integrated control system, which can maintain the ozone dosage ≤30mg / L by dynamically adjusting the return ratio.

[0031] Preferably, the ratio of the height to the diameter of the filter media layer in the biological filter is 1.5-2:1.

[0032] Preferably, the volume of the packing zone in the integrated ozone-biological contact oxidation tank accounts for 60-70% of the total tank volume.

[0033] The technical effects and advantages of this invention are as follows:

[0034] 1. Through the synergistic effect of ozone oxidation, biodegradation and ultraviolet disinfection, multi-level control of antibiotic resistance genes is achieved. Ozone destroys the DNA / RNA structure of antibiotic resistance genes by directly oxidizing electron-rich groups or indirectly generating ·OH free radicals. In the compound bacterial agent, Pseudomonas secretes extracellular enzymes to specifically hydrolyze antibiotic resistance gene fragments. Bacillus enriches residual genes through biosorption. Finally, ultraviolet light completely inactivates residual antibiotic resistance genes by forming DNA pyrimidine dimers. The synergistic effect of the three factors greatly improves the total removal rate of antibiotic resistance genes and more thoroughly blocks their transmission path.

[0035] 2. Ozone oxidation converts recalcitrant organic matter into short-chain small molecules, improving the biodegradability of wastewater and creating conditions for biological degradation. The biological contact oxidation stage degrades ozone intermediates through nitrifying bacteria, Pseudomonas, and other microorganisms, reducing the accumulation of toxic intermediates and lowering ozone consumption requirements. This significantly reduces electricity costs and ozone generator operation and maintenance costs, and avoids the risk of byproducts caused by high doses of ozone.

[0036] 3. The hydrolysis acidification tank decomposes large molecular organic matter through anaerobic bacteria, laying a stable water quality foundation for subsequent treatment. The integrated ozone-biological contact oxidation tank is equipped with a return pipeline, which can dynamically adjust to cope with water quality fluctuations. The biological activated carbon filter media of the biological filter further adsorbs and degrades residual pollutants. Combined with precise ultraviolet disinfection parameters, the system can still operate stably when the concentration of organic matter and the abundance of antibiotic resistance genes in medical wastewater fluctuate. It is suitable for the special treatment of antibiotic resistance genes in medical wastewater of various hospitals, and its treatment effect is particularly outstanding for wastewater with high risk of antibiotic resistance genes. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating the overall process flow of the present invention.

[0038] Figure 2 This is a flowchart of the steps of the present invention.

[0039] The attached diagram is labeled as follows: 1. Inlet tank; 2. Peristaltic pump; 3. Hydrolysis acidification tank; 4. Agitator; 5. Valve; 6. Integrated ozone-biological contact oxidation tank; 7. Ozone generator; 8. Aerator; 9. Aeration pump; 10. Elastic three-dimensional packing; 11. Elastic packing support; 12. Mixed liquor return pump; 13. Biological filter; 14. Water flow distributor; 15. Filter pad; 16. Biological activated carbon; 17. Ultraviolet disinfection device; 18. Ultraviolet lamp assembly; 19. Control system; 20. Outlet tank. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention provides an ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater. The medical wastewater used in this embodiment has the following characteristics: chemical oxygen demand (COD) 180-250 mg / L, ammonia nitrogen 25-40 mg / L, antibiotic residues (mainly sulfonamides and quinolones) 1.2-3.5 mg / L, and antibiotic resistance genes including sul1 and qnrS, with an initial relative abundance of 5.2 × 10⁻⁶ as detected by quantitative real-time PCR. 5 -8.6×10 6 The copy number per ml and the B / C ratio (biodegradability) were 0.20-0.25.

[0042] The functional microbial agents and fillers required in the embodiments of the present invention are as follows:

[0043] Compound microbial agent: Pseudomonas and Bacillus are selected, screened and domesticated in the laboratory, and then compounded at a bacterial count ratio of 1:1.5, supplemented with nitrifying bacteria and denitrifying bacteria (20% by mass) to form a compound microbial agent;

[0044] Microbial agent immobilization: The microbial agent was immobilized using a sodium alginate-activated carbon microsphere encapsulation method, with sodium alginate concentration of 2% and activated carbon concentration of 15%. The microbial agent loading density after encapsulation was 1.5 × 10⁻⁶. 5 CFU / g packing material;

[0045] Packing material: Elastic three-dimensional packing material 10 (diameter 15cm, length 1.2m) is selected, which is sterilized and loaded with the above-mentioned compound microbial agent, and fixed by elastic packing material support 11.

[0046] The parameters of each unit in the processing system required to be built in this embodiment of the invention are as follows:

[0047] Hydrolysis acidification tank 3 has an effective volume of 80L and adopts an upward flow water distribution device. It is equipped with a stirrer 4 (power 30W) and controls the hydraulic retention time to 2.5h, pH 6.8, temperature 28℃, and upward flow velocity to 1.2m / h.

[0048] The integrated ozone-biological contact oxidation tank 6 has a total volume of 200L, with the ozone section accounting for 40% and the biological section accounting for 60% (the packing area accounts for 65% of the total tank volume). The ozone section is equipped with a jet injector (connected to the ozone generator 7) and an aerator 8 (connected to the aeration pump 9). The ozone dosage is 20mg / L, and the contact time is 40min (range 30-60min). The biological section is filled with elastic three-dimensional packing material 10 loaded with compound bacterial agent, and the hydraulic retention time is controlled at 7h with dissolved oxygen at 3mg / L. A porous baffle (pore diameter 3mm) is installed between the ozone section and the biological section, and the microbial retention rate is 96%.

[0049] The return pipeline recirculates 40% of the effluent from the biological section back to the ozone section inlet. The pipeline is equipped with a real-time ozone concentration monitor of the integrated control system 19 to dynamically adjust the recirculation ratio to maintain the ozone dosage ≤30mg / L.

[0050] Biological filter 13, effective volume 60L, built-in water flow distributor 14, filter pad 15, filled with 3mm particle size biological activated carbon 16, filtration rate 4m / h, filter media layer height to diameter ratio 1.8:1;

[0051] The ultraviolet disinfection device 17 is equipped with a 254nm wavelength ultraviolet lamp assembly 18, with a radiation dose of 45mJ / cm². 2 Processing time: 20 minutes;

[0052] The connection is as follows: Inlet pool 1 → Peristaltic pump 2 → Hydrolysis acidification pool 3 → Valve 5 → Integrated ozone-biological contact oxidation pool 6 → Valve 5 → Biological filter 13 → Valve 5 → Ultraviolet disinfection device 17 → Outlet pool 20.

[0053] The specific process of this invention embodiment is as follows:

[0054] S1. Hydrolysis and acidification pretreatment: Medical wastewater is pumped to hydrolysis and acidification tank 3 via peristaltic pump 2. Under anaerobic conditions, the hydrolysis and acidification bacteria decompose large organic molecules (such as proteins and polysaccharides) into small organic acids (acetic acid, propionic acid, etc.). Operational results show that the effluent COD is reduced to 120-160 mg / L, and the B / C ratio is increased to 0.35-0.40, creating conditions for subsequent ozone-biological treatment.

[0055] S2, ozone-biological contact oxidation synergistic treatment;

[0056] In section S2.1, the hydrolyzed and acidified effluent enters the ozone section. Ozone disrupts the nucleic acid structure of antibiotic resistance genes (e.g., base breakage, phosphodiester bond hydrolysis) through direct oxidation (attacking electron-rich groups of antibiotic resistance genes) and indirect oxidation (generating ·OH free radicals), while also degrading some antibiotic residues. Testing showed that the relative abundance of antibiotic resistance genes in this section decreased to 1.2 × 10⁻⁶. 5 -2.1×105 Copy number / mL, removal rate 75-80%;

[0057] In the S2.2 biological stage, effluent from ozone treatment directly enters the biological stage. The compound bacterial agent works synergistically; Pseudomonas secretes extracellular enzymes that specifically hydrolyze the phosphodiester bonds of antibiotic resistance genes; Bacillus enriches antibiotic resistance gene fragments through biosorption; and nitrifying and denitrifying bacteria simultaneously degrade ammonia nitrogen. After operation, the relative abundance of antibiotic resistance genes further decreased to 3.0 × 10⁻⁶. 4 -5.0×10 4 With a copy number / mL, the degradation rate of intermediate products (such as aldehydes) generated by ozone oxidation reaches 90%, achieving a synergistic cycle of ozone improving biodegradability and reducing ozone consumption.

[0058] S3 and Biological Filter 13: Wastewater treated by ozone-biological contact oxidation enters biological filter 13. Activated carbon 16 further removes residual organic matter and antibiotic resistance genes through the synergistic effect of adsorption and biodegradation. The effluent COD is reduced to 50-70 mg / L, ammonia nitrogen to 5-8 mg / L, and the relative abundance of antibiotic resistance genes to 5.0 × 10⁻⁶. 3 -8.0×10 4 Copy number / mL;

[0059] S4. Ultraviolet disinfection: The effluent from biological filter 13 enters the ultraviolet disinfection device 17, where 254nm ultraviolet light is emitted at 45mJ / cm². 2 After 20 minutes of radiation treatment, the DNA pyrimidine dimer formation efficiency reached 93%, ultimately inactivating residual microorganisms and antibiotic resistance genes.

[0060] The removal effects of each indicator after 30 days of operation of the process or system are shown in the table below:

[0061]

[0062] Comparative experiments show that:

[0063] Ozone treatment alone (with the biological section closed): 45 mg / L of ozone is required to achieve the ARGs destruction effect of 20 mg / L ozone in this process, and the accumulation of intermediate products is 3 times that of this process;

[0064] Biological treatment alone (with the same system and ozone section off): The total removal rate of antibiotic resistance genes is only 60-65%, and the activity of the bacterial agent is limited due to insufficient biodegradability;

[0065] This process has been verified to reduce ozone dosage by 40-50% through ozone-biological synergy, while avoiding secondary pollution.

[0066] The final effluent COD ≤ 50 mg / L, ammonia nitrogen ≤ 5 mg / L, and ARGs relative abundance < 10 3 The copy number / mL meets the discharge standards for water pollutants in medical institutions, and no disinfection byproducts (such as trihalomethanes) were detected.

[0067] in conclusion:

[0068] This invention demonstrates the highly efficient removal of antibiotic resistance genes from medical wastewater through a process involving hydrolysis acidification, ozone-biological contact oxidation, biological filter 13, and ultraviolet disinfection.

[0069] 1. Through the synergistic effect of compound bacterial agents and ozone, antibiotic resistance genes are blocked at both the gene level (nucleic acid breakage) and the bacterial community level (host bacterial inactivation);

[0070] 2. The process parameters (such as ozone dosage, bacterial agent ratio, and hydraulic retention time) are all within the appropriate limits, and the operation is stable and has strong resistance to shock loads;

[0071] 3. Compared with traditional processes, ozone dosage is reduced by 30-50%, operating costs are reduced by 25-30%, and there is no secondary pollution.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ozone-biological coupled degradation process for antibiotic resistance genes in medical wastewater, characterized in that: Specifically, the following steps are included: S1. Hydrolysis and acidification pretreatment: Medical wastewater enters the hydrolysis and acidification tank (3) in an upward flow manner. Under the conditions of hydraulic retention time of 2-3h, pH 6.0-7.5, temperature 15-40℃, and upward flow velocity of 1.0-1.5m / h, macromolecular organic matter is decomposed into small molecule substances. S2, Ozone-Biological Contact Oxidation Synergistic Treatment: S2.

1. The hydrolyzed and acidified effluent is treated with ozone at a concentration of 10-30 mg / L for 30-60 minutes via an ejector to destroy the nucleic acid structure of antibiotic resistance genes. S2.

2. The effluent treated by ozone is directly introduced into the biological section of the same reaction tank. Under the conditions of hydraulic retention time of 6-8h and dissolved oxygen concentration of 2-4mg / L, the intermediate products are degraded by the elastic three-dimensional packing material (10) loaded with compound bacterial agent. S3. Deep treatment by biological filter (13): Deep treatment is carried out by biological activated carbon (16) filter with water flow distributor (14), wherein the filter media particle size is 2-4mm and the filtration rate is controlled at 3-5m / h. S4. Ultraviolet disinfection, at 30-60 mJ / cm². 2 Radiation dose treatment for 10-30 minutes; In this process, steps S2.1 and S2.2 form a synergistic cycle: ozone oxidation improves the biodegradability of organic matter, the biodegradation process reduces ozone consumption, and the compound microbial agent can target and degrade antibiotic resistance genes; the compound microbial agent contains nitrifying bacteria, denitrifying bacteria, and Pseudomonas and / or Bacillus.

2. The ozone-biocoupled degradation process for antibiotic resistance genes in medical wastewater according to claim 1, characterized in that: The Pseudomonas species can secrete extracellular enzymes that can specifically hydrolyze the phosphodiester bonds of antibiotic resistance genes, while Bacillus species can enrich antibiotic resistance gene fragments through biosorption.

3. The ozone-biocoupled degradation process for antibiotic resistance genes in medical wastewater according to claim 1, characterized in that: Pseudomonas and Bacillus were mixed in a ratio of 1:1 to 1:2 and then fixed on an elastic three-dimensional packing material (10) for targeted degradation of antibiotic resistance gene fragments in the ozone-treated biological segment.

4. The ozone-biocoupled degradation process for antibiotic resistance genes in medical wastewater according to claim 1, characterized in that: In step S2.2, the composite bacterial agent is immobilized by encapsulation with sodium alginate-activated carbon microspheres, and the bacterial agent loading density is ≥10. 5 CFU / g packing material.

5. The ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater according to claim 1, characterized in that: In step S4, ultraviolet disinfection is performed using a 254nm wavelength ultraviolet lamp to ensure that the formation efficiency of DNA pyrimidine dimers is >90%.

6. The ozone-biocoupled degradation process for antibiotic resistance genes in medical wastewater according to claim 1, characterized in that: It also includes a system for implementing the process, which comprises the following components connected in sequence: The water inlet tank (1) is connected to the hydrolysis acidification tank (3) via a peristaltic pump (2). The hydrolysis acidification tank (3) is equipped with an upward flow water distribution device and has an internal stirrer (4) for mixing and promoting the hydrolysis acidification reaction. The hydrolysis acidification tank (3) is connected to the integrated ozone-biological contact oxidation tank (6) through the valve (5). The integrated ozone-biological contact oxidation tank (6) includes an ozone section and a biological section. In the ozone section, the jet injector is connected to the ozone generator (7), and the aerator (8) is connected to the aeration pump (9) for ozone addition and distribution. The biological section is filled with an elastic three-dimensional packing material (10) loaded with compound bacterial agent. The elastic three-dimensional packing material is fixed by an elastic packing material support (11) and is equipped with a mixed liquid return pump (12) for mixed liquid return. The integrated ozone-biological contact oxidation tank (6) is connected to the biological filter (13) through a valve (5). The biological filter (13) has a built-in water flow distributor (14), a filter pad (15), and biological activated carbon (16) with a particle size of 2-4 mm. The biological filter (13) is connected to the ultraviolet disinfection device (17) through the valve (5). The ultraviolet disinfection device (17) is equipped with an ultraviolet lamp assembly (18), and the radiation dose is regulated by the control system (19). The ultraviolet disinfection device (17) is connected to the water outlet pool (20); It also includes a return pipeline to return 30-50% of the effluent from the biological section to the ozone section inlet, with a valve (5) installed on the pipeline to control the flow rate.

7. The ozone-biological coupling degradation process for antibiotic resistance genes in medical wastewater according to claim 6, characterized in that: A porous baffle with a pore size of ≤5mm is provided between the ozone section and the biological section to ensure unobstructed water flow and a microbial retention rate of ≥95%.

8. The ozone-biocoupled degradation process for antibiotic resistance genes in medical wastewater according to claim 6, characterized in that: The return pipeline is equipped with a real-time ozone concentration monitor of an integrated control system (19), which can maintain the ozone dosage ≤30mg / L by dynamically adjusting the return ratio.

9. The ozone-biocoupled degradation process for antibiotic resistance genes in medical wastewater according to claim 6, characterized in that: The ratio of the height to the diameter of the filter media layer in the biological filter (13) is 1.5-2:

1.

10. The ozone-biocoupled degradation process for antibiotic resistance genes in medical wastewater according to claim 6, characterized in that: The volume of the packing area of ​​the integrated ozone-biological contact oxidation tank (6) accounts for 60-70% of the total volume of the tank.

Images