Electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage and application of electrochemical disinfection treatment method

Abstract

The invention discloses an electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage and application of the electrochemical disinfection treatment method, and belongs to the technical field of water treatment, and the antibiotic-resistant pollutants include but not limited to drug-resistant bacteria, drug-resistant genes or drug-resistant plasmids and the like. The method comprises the following steps: adding a Fe3O4-PAC particle electrode into an effective space between a cathode plate and an anode plate in an electrochemical reactor, and carrying out electrochemical disinfection treatment on wastewater to remove antibiotic resistant pollutants in the wastewater; the Fe3O4-PAC particle electrode is prepared from a reaction system containing ferric salt, alkali and powdered activated carbon PAC through a chemical precipitation method. The method is simple and efficient, drug-resistant bacteria, drug-resistant genes, drug-resistant plasmids and the like in the sewage can be effectively reduced, and a feasible strategy is provided for risk prevention and control of drug resistance of harmful bacteria and antibiotics in the sewage.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to an electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage and an application thereof. Background Art

[0002] In the fields of medicine, agriculture, and animal husbandry, the widespread use of antibiotics has led to the emergence of drug-resistant bacteria and the development of antibiotic resistance. Antibiotic resistance is an increasingly serious global public health issue, and bacterial antibiotic resistance has imposed a huge burden on human health and social economy. Antibiotic resistance genes (ARGs) are the key to bacterial resistance, and resistance genes can be transferred and spread between bacteria through genetic elements such as plasmids. Conventional sewage treatment technologies, such as screen filtration, sedimentation, and ultrafiltration technology, are mainly aimed at removing suspended solids, organic matter and other impurities in water. The removal effect of antibiotic-resistant pollutants such as resistant bacteria and resistance genes is limited, and it still poses a safety risk to the environment and requires further treatment.

[0003] The sewage treatment system brings together a large number of antibiotics, drug-resistant genes and drug-resistant bacteria from different sources, which makes the sewage treatment system an important repository of antibiotic-resistant pollutants. At the same time, the sewage treatment system is also an important node for the spread of antibiotic resistance from humans and animals to the environment, and is an important source of environmental antibiotic resistance. Disinfection treatment process is an indispensable part of controlling microbial contamination in sewage treatment systems. However, the current traditional disinfection treatment process has limited effect on the treatment of drug-resistant bacteria, drug-resistant genes, drug-resistant plasmids, etc. in sewage treatment systems. After entering the environment, the drug-resistant genes and drug-resistant plasmids carried by these drug-resistant bacteria can still be spread among environmental flora through conjugation and other pathways, posing a huge threat to environmental health.

[0004] Although some methods for removing DNA or drug-resistant genes in sewage are disclosed in the prior art (such as Chinese patent documents with publication numbers CN117003426A, CN110776078A, CN118546919A, etc.), there is a problem of high cost of reagents, and the treatment efficiency needs to be further improved. Therefore, it is necessary to develop new disinfection treatment technologies to strengthen the control of antibiotic-resistant pollutants in the effluent of sewage treatment plants. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides an electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage. The method is simple and efficient and can effectively reduce drug-resistant bacteria, drug-resistant genes, drug-resistant plasmids, etc. in sewage.

[0006] The specific technical solutions adopted are as follows:

[0007] An electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage, comprising: adding Fe3O4-PAC particle electrodes into the effective space between the cathode plate and the anode plate in an electrochemical reactor, and electrochemically disinfecting the wastewater to remove the antibiotic-resistant pollutants in the sewage;

[0008] The Fe3O4-PAC particle electrode is prepared by a chemical precipitation method using a reaction system containing iron salt, alkali and powdered activated carbon PAC.

[0009] The method of the present invention uses Fe3O4-PAC (powdered activated carbon) as a particle electrode, which is added into the effective space between the cathode plate and the anode plate in the electrochemical reactor. On the one hand, the cathode and the anode can generate a large number of hydroxyl radicals under the action of the electric field, and the disinfection efficiency of hydroxyl radicals can reach 10 times that of chlorine disinfectants. 3 -10 4 times, and it can directly damage DNA with its high redox potential. On the other hand, the electrochemical reactor will also generate a large amount of free chlorine (HClO, ClO - , Cl2), these free chlorine can effectively reduce drug-resistant bacteria, and part of the free chlorine will be further converted into hydroxyl radicals under the action of Fe(II) in Fe3O4, further improving the treatment effect. The method of the present invention can reduce antibiotic-resistant pollutants such as antibiotic-resistant bacteria, drug-resistant genes, and drug-resistant plasmids by virtue of good free chlorine and free radical generation performance.

[0010] Specifically, antibiotic-resistant pollutants include, but are not limited to, resistant bacteria, resistant genes or resistant plasmids, etc.

[0011] Preferably, the anode is a ruthenium-iridium-titanium electrode, and the cathode is a titanium electrode.

[0012] Preferably, based on the amount of wastewater treated, the amount of Fe3O4-PAC particle electrode added is 0.05-0.3 g / L; during the electrochemical disinfection treatment, constant current treatment is adopted, and the current density is 1-5 mA / cm 2 Under the above preferred parameters, the treatment effect on antibiotic-resistant pollutants is good.

[0013] Preferably, the electrochemical disinfection treatment time is 20-120 minutes.

[0014] Further preferably, based on the amount of wastewater treated, the amount of Fe3O4-PAC particle electrode added is 0.1 g / L; during the electrochemical disinfection treatment, a constant current treatment is used for 45 min, and the current density is 3 mA / cm 2Under the above parameters, the method of the present invention can completely inactivate typical drug-resistant bacteria, and the removal efficiency of β-lactam resistance genes carried by these drug-resistant bacteria can reach more than 94%, and the removal efficiency of plasmids can reach more than 95%.

[0015] Preferably, the preparation method of the Fe3O4-PAC particle electrode includes: preparing a mixed iron salt solution of divalent iron salt and trivalent iron salt, heating it to 75-85°C, adding alkali and powdered activated carbon PAC, reacting at a constant temperature for 20-40 minutes under an inert gas environment, recovering the solid product, washing and magnetically separating it to obtain the Fe3O4-PAC particle electrode.

[0016] Further preferably, the molar ratio of the divalent iron salt to the trivalent iron salt is 1:1.5-2.

[0017] Further preferably, the alkali is ammonia water, and the mass ratio of iron salt to powdered activated carbon PAC is 3-6:10; the dosage of powdered activated carbon PAC accounts for about 8%-12% of the entire reaction system.

[0018] The present invention also provides the application of the electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage in the field of wastewater treatment.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The electrochemical disinfection treatment method provided by the present invention can achieve efficient removal of drug-resistant bacteria and the drug-resistant genes and drug-resistant plasmids they carry.

[0021] (2) In the bacterial suspension simulated wastewater experiment, the electrochemical disinfection treatment method of the present invention has a current density of 3 mA / cm 2 When the particle electrode addition amount is 0.1g / L and the treatment time is 45min, typical resistant bacteria can be completely inactivated, and the removal efficiency of β-lactam resistance genes carried by these resistant bacteria can reach more than 94%, and the removal efficiency of plasmids can reach more than 95%; and this electrochemical disinfection treatment method can still maintain a good treatment effect on actual sewage.

[0022] (3) The method of the present invention can achieve efficient removal of drug-resistant bacteria, drug-resistant genes and drug-resistant plasmids through the generation of free chlorine and free radicals. The method of the present invention can also reduce the diversity of microbial communities in sewage and has a good reduction effect on potential pathogenic microorganisms, providing a feasible strategy for the risk prevention and control of harmful bacteria and antibiotic resistance in sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1The morphological characteristics of powdered activated carbon PAC and Fe3O4-PAC particle electrodes, A is the SEM image of PAC, B is the SEM image of Fe3O4-PAC, C is the EDS image of PAC, and D is the EDS image of Fe3O4-PAC.

[0024] Figure 2 These are the structural characteristics of powdered activated carbon PAC and Fe3O4-PAC particle electrodes, A is the infrared spectrum, and B is the XRD diagram.

[0025] Figure 3 Schematic diagram of the electrochemical treatment device.

[0026] Figure 4 The figures are the removal effect diagrams of drug-resistant bacteria under different conditions by the method of the present invention, wherein A is the removal effect diagram of drug-resistant bacteria under different current densities, and B is the removal effect diagram of drug-resistant bacteria under different Fe3O4-PAC particle electrode addition amounts.

[0027] Figure 5 The figures are the effect diagrams of the method of the present invention on removing drug-resistant genes and drug-resistant plasmids carried by drug-resistant bacteria, A is the effect diagram of removing drug-resistant plasmids, and B is the effect diagram of removing drug-resistant genes.

[0028] Figure 6 The figures are the treatment effect diagrams of the method of the present invention on actual sewage, A is the reduction effect diagram of 16S rRNA, B is the reduction effect diagram of drug-resistant gene ARGs and mobile elements, and C is a comparison diagram of the removal effects of electrochemical disinfection and chlorine disinfection.

[0029] Figure 7 This is a graph showing the fold change of typical potential pathogenic bacterial genera after treatment with different disinfection techniques. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the examples and accompanying drawings. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods of the following examples that do not specify specific conditions are usually performed under normal conditions or under conditions recommended by the manufacturer. The content that is not described in detail in this specification sheet belongs to the prior art known to professionals in the field. The experimental materials used in the following examples, if not otherwise specified, can be purchased by conventional biochemical reagent companies.

[0031] Example 1 Preparation of Fe3O4-PAC particle electrode

[0032] 2.1 g FeSO4·7H2O and 3.1 g FeCl3·6H2O were weighed into 80 mL deionized water, stirred and dissolved under nitrogen conditions to obtain a mixed iron salt solution, the mixed iron salt solution was heated to 80°C, and 10 mL of 25% ammonia solution and 10 g powdered activated carbon PAC were added, and the mixture was continuously stirred in a nitrogen-filled environment and reacted at a constant temperature for 30 min. After the reaction, the solid product was recovered by filtration, magnetic separation, etc., and washed three times with anhydrous ethanol and deionized water respectively to remove the unreacted reagents to obtain a Fe3O4-PAC particle electrode, which was used for subsequent characterization and testing.

[0033] When the molar ratio of divalent iron salt to trivalent iron salt is 1:1.5-2; the dosage of powdered activated carbon PAC accounts for 8%-12% of the entire reaction system; and the reaction temperature is 75-85°C, Fe3O4-PAC particle electrodes can be successfully prepared.

[0034] Example 2 Characterization of Fe3O4-PAC Particle Electrode

[0035] The powdered activated carbon PAC and the Fe3O4-PAC particle electrode prepared in Example 1 were characterized. Scanning electron microscopy and energy spectrum analysis showed that ( Figure 1 AD in the figure), the surface of the original PAC without Fe3O4 doping is relatively smooth, but after loading Fe3O4, a large number of fluffy and rough particles grow on the surface of PAC. The original PAC is mainly composed of carbon and oxygen, and there is no obvious iron doping on the surface (the iron content is 0%). The surface of the treated Fe3O4-PAC contains not only carbon and oxygen elements, but also about 9.6% iron by mass. This preliminarily proves that the fluffy and rough particles on the surface of Fe3O4-PAC are particles containing iron. Further infrared spectroscopy and XRD analysis show that ( Figure 2 A and B in Figure 2), compared with PAC, the FTIR spectrum of Fe3O4-PAC is at 558cm -1 There is an additional characteristic peak on the left and right, which may be caused by the vibration of the Fe-O group in Fe3O4. At the same time, compared with the standard comparison card, Fe3O4-PAC has a characteristic peak that is highly consistent with the standard Fe3O4, indicating that Fe3O4 is successfully loaded. The results of the comprehensive morphological characterization and structural characterization show that the present invention successfully synthesized the Fe3O4-PAC particle electrode.

[0036] Example 3 Electrochemical disinfection treatment

[0037] (1) This embodiment constructs Figure 3The electrochemical disinfection device shown is a rectangular electrolytic cell with a length, width and height ratio of 10:4.2:6.5. The device uses a titanium electrode as a cathode and a ruthenium-iridium-titanium electrode as an anode. The distance between the cathode plate and the anode plate is 2 cm. The Fe3O4-PAC particle electrode prepared in Example 1 is filled in the effective space between the cathode plate and the anode plate in the electrochemical reactor to electrochemically disinfect the wastewater to remove antibiotic-resistant pollutants in the wastewater; the addition amount of the Fe3O4-PAC particle electrode is set to 0, 0.05, 0.1, 0.2, 0.3 g / L, respectively, and the current density is set to 1, 3, 5 mA / cm 2 .

[0038] (2) Typical drug-resistant strains (isolated from sewage treatment systems) were inoculated into LB medium and cultured overnight at a constant temperature. The cells were centrifuged and washed repeatedly, and then resuspended in simulated electrolyte (with NaCl and Na2SO4 added) and adjusted to a final concentration of 10 8 CFU / mL. The diluted drug-resistant bacterial suspension was taken as simulated wastewater, the pH value of the electrolyte was adjusted, and it was treated by the method in (1) above. Samples at different treatment time points were collected, diluted to a suitable concentration gradient, and evenly spread on LB solid culture medium containing the corresponding antibiotics. After constant temperature overnight culture, the samples were counted.

[0039] The results are as follows Figure 4 As shown in A and B in the figure, under the experimental conditions of simulated electrolyte, the current density is 3mA / cm 2 When the particle electrode addition amount is 0.1g / L and the treatment time is 45min, the electrochemical disinfection technology can completely inactivate typical drug-resistant bacteria, and the electrochemical disinfection technology is less affected by pH and is a relatively stable disinfection treatment technology.

[0040] (3) Take appropriate amount of samples at different time points during the electrochemical disinfection process in (2), and filter and enrich them using a cellulose acetate microporous filter with a pore size of 0.22 μm. Use a DNA extraction kit to extract DNA, and use gel electrophoresis and Nanodrop nucleic acid concentration analyzer to identify the quality and concentration of the purified DNA product. Dilute the DNA sample to an appropriate concentration, and use fluorescent quantitative qPCR technology to characterize the abundance of drug-resistant genes and plasmids carried by typical drug-resistant bacteria.

[0041] The results are as follows Figure 5 As shown in A and B, the Fe3O4-PAC particle electrode addition amount is 0.1g / L and the current density is 3mA / cm 2The electrochemical technology's plasmid removal efficiency increased continuously before 45 minutes, and its removal efficiency at 45 minutes was greater than 95%. At the same time, the electrochemical disinfection technology had a similar trend in reducing drug-resistant genes and plasmids, gradually reaching a plateau at 45 minutes. At this time, three different types of β-lactam resistant plasmids (bla CTX-M ,bla NDM and bla TEM ) removal efficiency is greater than 94%. In general, the electrochemical disinfection technology of the present invention has a good reduction effect on drug-resistant genes and drug-resistant plasmids.

[0042] (4) The effluent from the secondary sedimentation tank of a municipal sewage treatment plant (actual sewage) was treated using the method in (1) above. The secondary effluent was fed into an electrochemical device and the current density was 3 mA / cm 2 Electrochemical disinfection was carried out under the condition of Fe3O4-PAC concentration of 0.1g / L, and sewage samples were collected at different treatment time points for subsequent DNA extraction. At the same time, a chlorine dosage of 4mg / L (traditional chlorine disinfection treatment) was selected for comparative experiments to compare the treatment effects of electrochemical technology using Fe3O4-PAC as particle electrode and traditional chlorine disinfection technology on actual sewage. The abundance of drug-resistant genes and plasmids was determined by fluorescence quantitative qPCR, and the characteristics of bacterial community structure were identified by high-throughput sequencing.

[0043] The experimental results show that ( Figure 6 AC in the sample), with the increase of treatment time, the abundance of 16S rRNA gene continued to decrease. For different types of typical drug-resistant genes, electrochemical technology can achieve a reduction of 1.17-1.8 orders of magnitude in 45 minutes. For four different types of plasmids, IncP, IncF, IncW, and IncX, the method of the present invention can also achieve a removal of 0.83-1.87 orders of magnitude. Compared with the pure bacteria system, the removal effect of the method of the present invention on actual sewage is reduced, which may be affected by pollutants such as antibiotics and organic matter in actual sewage, but on the whole, the technology can still remove more than 90% of BLRGs and plasmid fragments, indicating that the electrochemical technology can still maintain a good treatment effect on actual sewage. At the same time, chlorine disinfection has a significant effect on bla CTX-M ,bla NDM and bla TEMThe removal effect of electrochemical technology on the drug-resistant gene ARGs was 0.08-0.37 orders of magnitude, and the removal effect on the drug-resistant gene sul1 was 0.31 orders of magnitude, while the reduction effect of electrochemical technology on the above drug-resistant gene ARGs was 1.17-2.33 orders of magnitude, which shows that electrochemical technology is also significantly better than traditional chlorine disinfection in removing drug-resistant gene ARGs in actual sewage. In addition, chlorine disinfection can only remove 0.33 orders of magnitude of a class of integrons, while electrochemical disinfection has a reduction efficiency of 1.84 orders of magnitude for a class of integrons.

[0044] (5) The inventors further explored the changes in potential human pathogenic bacteria after electrochemical disinfection and chlorine disinfection ( Figure 7 ). After electrochemical treatment, the relative abundance of 13 typical potential pathogenic bacteria genera decreased, while after chlorine disinfection, only 3 genera decreased in abundance. For example, after electrochemical treatment, the abundance of potential pathogenic bacteria genera Bacteroides, Aeromonas, and Legionella decreased by 8%-85%, while after chlorine disinfection, they were enriched by 84%-185%. In summary, the electrochemical disinfection technology of the present invention has a better control effect on potential pathogenic microorganisms.

[0045] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for electrochemical disinfection of antibiotic-resistant pollutants in sewage, characterized in that: include: Fe3O4-PAC particle electrodes are added into the effective space between the cathode plate and the anode plate in the electrochemical reactor to electrochemically disinfect the wastewater to remove antibiotic resistant pollutants in the wastewater; The Fe3O4-PAC particle electrode is prepared by a chemical precipitation method using a reaction system containing iron salt, alkali and powdered activated carbon PAC.

2. The electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to claim 1, characterized in that: The anode is a ruthenium-iridium-titanium electrode, and the cathode is a titanium electrode.

3. The electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to claim 1, characterized in that: Based on the amount of wastewater treated, the amount of Fe3O4-PAC particle electrode added is 0.05-0.3g / L.

4. The electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to claim 1, characterized in that: During the electrochemical disinfection process, constant current treatment is used with a current density of 1-5 mA / cm 2 .

5. The electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to claim 1, characterized in that: The electrochemical disinfection treatment time is 20-120 minutes.

6. The electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to claim 1, characterized in that: The preparation method of the Fe3O4-PAC particle electrode comprises: preparing a mixed iron salt solution of divalent iron salt and trivalent iron salt, heating to 75-85°C, adding powdered activated carbon PAC and alkali, reacting at a constant temperature for 20-40 minutes under an inert gas environment, recovering the solid product, washing and separating to obtain the Fe3O4-PAC particle electrode.

7. The electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to claim 6, characterized in that: The molar ratio of the divalent iron salt to the trivalent iron salt is 1:1.5-2.

8. The electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to claim 6, characterized in that: The alkali is ammonia water; the mass ratio of the iron salt to the powdered activated carbon PAC is 3-6:

10.

9. Application of the electrochemical disinfection treatment method for antibiotic-resistant pollutants in sewage according to any one of claims 1 to 8 in the field of wastewater treatment.

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