Method for removing antibiotics by coupling magnetic biochar with dissimilatory iron reducing bacteria

Abstract

The invention discloses a method for removing antibiotics by coupling magnetic biochar with dissimilatory iron reducing bacteria, and belongs to the field of sewage treatment. The method comprises the following steps: (1) selecting Shewanella oneidensis for enrichment culture; (2) preparing magnetic biochar; (3) mixing the bacterial strains subjected to enrichment culture in the step (1) with the magnetic biochar prepared in the step (2), so that the bacterial strains are fully adsorbed on the surface of the magnetic biochar to obtain the magnetic biochar coupled dissimilatory iron-reducing bacteria; and (4) fully contacting the magnetic charcoal coupled dissimilatory iron reducing bacteria with antibiotic wastewater to remove antibiotics in the wastewater. High density of microorganisms can be achieved, biological activity of the microorganisms can be maintained, introduction of the microorganisms effectively makes up for the single adsorption characteristic of the magnetic biochar, meanwhile, the magnetic biochar can protect the microorganisms, reduce environmental stress and ensure the stability of the microorganisms in degrading pollutants, and the removal efficiency of the pollutants is remarkably improved through cooperation of the microorganisms and the magnetic biochar.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and in particular to a method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria. Background Art

[0002] With the advancement of science and technology and the improvement of industrial standards, people's living standards have greatly improved. However, this has also led to numerous environmental problems. Antibiotics, a widely used drug for the prevention and treatment of infectious diseases in animals and humans, saw a significant increase in their use in the early 2000s. However, in recent years, antibiotics have become an emerging micropollutant. In reality, the amount of antibiotics metabolized and absorbed by animals and humans is very small; a significant portion is discharged into the aquatic environment as metabolites or raw materials. Furthermore, pharmaceutical companies and medical institutions inevitably discharge large amounts of antibiotic-containing wastewater during the production and use of antibiotics. This antibiotic wastewater discharge into water bodies poses a significant environmental risk, with levels far exceeding environmental protection limits. Furthermore, antibiotics and their metabolites are significantly toxic to aquatic organisms and microorganisms, potentially disrupting ecological balances. Persistent antibiotics accumulate in aquatic plants and animals, ultimately affecting humans through the food chain.

[0003] Nowadays, biological methods are widely used in the removal of antibiotics. The introduction of microorganisms can significantly reduce the use of chemical reagents, avoid pollutant residues, and rely on their reproductive capacity to achieve continuous and effective operation, thereby reducing reaction costs. However, the selection of microorganisms that can achieve better antibiotic removal requires continuous creative work by scientific researchers to discover. In addition, in order to provide a good living environment for microorganisms, biochar is currently often used to solidify microbial flora. However, in existing patents, biochar only acts as a carrier and does not promote the microbial flora. For example, Chinese invention patent application publication number CN115784469A discloses a modified biochar composite material for encapsulating microorganisms and its preparation and application. It mixes magnetic biochar with alginate to obtain a carrier, loads the composite microorganism on the carrier, and cross-links and solidifies it. For example, Chinese invention patent application publication number CN115960783A discloses an anaerobic microbial combination with sulfonamide antibiotic degradation function and its application. It provides two anaerobic microorganisms for sulfonamide antibiotic treatment and makes them into microbial immobilized bacterial pellets with sodium alginate and biochar. Summary of the Invention

[0004] The purpose of the present invention is to propose a method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria. The method adopts Shewanella Oneida, which can utilize the Fe on the magnetic biochar to remove the antibiotics. 3+ Electron transfer is carried out to achieve effective removal of antibiotics.

[0005] The technical solution adopted by the present invention is:

[0006] A method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria comprises the following steps:

[0007] (1) Select bacterial strains and perform enrichment culture;

[0008] Shewanella Oneida was used as the bacterial strain, which was inoculated into LB liquid medium, aerobically enriched in a constant temperature water bath shaker, and then subcultured;

[0009] (2) Preparation of magnetic biochar;

[0010] (3) Magnetic biochar coupled with dissimilatory iron-reducing bacteria;

[0011] The bacterial strain enriched and cultured in step (1) is mixed with the magnetic biochar prepared in step (2), so that the bacterial strain is fully adsorbed on the surface of the magnetic biochar, thereby obtaining magnetic biochar-coupled dissimilatory iron-reducing bacteria;

[0012] (4) antibiotic removal;

[0013] Magnetic biochar coupled with dissimilatory iron-reducing bacteria is fully contacted with antibiotic wastewater to remove antibiotics from the wastewater.

[0014] The beneficial technical effects of the present invention are as follows:

[0015] The present invention selects Shewanella Oneida, enriches and cultures it, and then mixes it with the prepared magnetic biochar to obtain magnetic biochar-coupled heterotrophic iron-reducing bacteria. The present invention can achieve high density of microorganisms and maintain their biological activity, allowing them to proliferate rapidly under suitable environmental conditions. The introduction of microorganisms effectively compensates for the single adsorption characteristics of magnetic biochar. At the same time, magnetic biochar can provide protection for microorganisms, reduce environmental stress, and ensure the stability of microbial degradation of pollutants. The synergistic effect formed by the two significantly improves the removal efficiency of pollutants. More importantly, the present invention combines Shewanella Oneida with the prepared magnetic biochar, which can also promote the electron transfer process, enhance the metabolic activity of microorganisms, and thus significantly improve the removal efficiency of antibiotic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope (SEM) image of the PM@MR-1 material prepared in Example 1 of the present invention;

[0017] Figure 2 This is an X-ray photoelectron spectroscopy (XPS) graph of the PM@MR-1 material prepared in Example 1 of the present invention;

[0018] Figure 3Figure 1 shows the removal effects of PM, MR-1, and PM@MR-1 prepared in Example 1 of the present invention on antibiotics in pig farming wastewater; (a) shows the removal effect of tetracycline (TC), and (b) shows the removal effect of ciprofloxacin (CIP);

[0019] Figure 4 Figure 1 shows the antibiotic removal effect of PM@MR-1 in pig farming wastewater under different antibiotic concentrations and the growth of MR-1. (a) shows the TC removal effect, (b) shows the CIP removal effect, and (c) shows the MR-1 growth.

[0020] Figure 5 Figure 1 shows the antibiotic removal effect of PM@MR-1 in pig farming wastewater under different pH conditions and the growth of MR-1. (a) shows the TC removal effect, (b) shows the CIP removal effect, and (c) shows the MR-1 growth.

[0021] Figure 6 Zeta potential diagram of PM prepared in Example 1 of the present invention under different pH conditions;

[0022] Figure 7 Figure 1 shows the antibiotic removal effect of PM@MR-1 prepared in Example 1 of the present invention on pig farming wastewater under different PM dosage conditions and the growth of MR-1; (a) shows the TC removal effect, (b) shows the CIP removal effect, and (c) shows the MR-1 growth;

[0023] Figure 8 The PM@MR-1 prepared in Example 1 of the present invention removes antibiotics from pig farming wastewater under different influencing factors, and the Fe content in the solution before and after the reaction 2+ Content diagram; (a) is different antibiotic concentration conditions, (b) is different pH conditions, and (c) is different PM dosage conditions;

[0024] Figure 9 1 is the Fe element X-ray photoelectron spectroscopy (XPS) diagram of the PM and PM@MR-1 materials prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] As a kind of iron-reducing bacteria, Shewanella Oneida (MR-1) has excellent Fe 3+It has the ability to reduce heavy metals such as magnesium and magnesium, and has the characteristics of efficient degradation of organic pollutants. However, the effect of using microorganisms alone is limited, and environmental pollutants can easily inhibit the activity of microorganisms. Therefore, a stable material is needed as an ideal microbial immobilization carrier to effectively protect the activity of microorganisms. Magnetic biochar can not only provide protection for microorganisms and reduce environmental stress, thereby ensuring the stability of microbial degradation of pollutants, but also promote the electron transfer process and enhance the metabolic activity of microorganisms. In addition, the introduction of microorganisms effectively compensates for the single adsorption characteristics of magnetic biochar, and the synergistic effect formed by the two significantly improves the removal efficiency of pollutants.

[0026] Based on this, the present invention proposes a method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria. This method uses pig manure as the raw material, and uses a combination of ferrous sulfate (iron source), urea (nitrogen source), and ascorbic acid (reducing agent) as the modifying agent. Through continuous optimization of the conditions, magnetic biochar (PM) is produced. This PM is then placed in the same environment with Shewanella Oneida (MR-1) that has been enriched for two generations and reached its logarithmic growth phase, resulting in the PM@MR-1 material through adsorption.

[0027] Specifically, a method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria comprises the following steps:

[0028] (1) Select bacterial strains and perform enrichment culture;

[0029] Shewanella Oneida was used as a bacterial strain, which was inoculated into LB liquid medium, aerobically enriched in a constant temperature water bath shaker, and then subcultured.

[0030] Shewanella oneidensis (MR-1, CCTCC AB 2013238) can be directly obtained from the market.

[0031] The glycerol tube containing Shewanella Oneida was inoculated into LB liquid culture medium, and the aerobic enrichment time was controlled to be 10-14 hours, and the subculture time was controlled to be 7-10 hours.

[0032] Specifically, LB liquid culture medium inoculated with Shewanella Oneida was shaken horizontally at 28-30° C. and 140-160 rpm.

[0033] The subculture process is as follows: Once Shewanella Oneida has reached the logarithmic growth phase, remove the supernatant by centrifugation at a speed of 4000-6000 rpm for 3-5 minutes. Then, add physiological saline and mix the solution thoroughly. Then, remove the supernatant by centrifugation. Repeat this process multiple times. Finally, add physiological saline and mix the solution thoroughly before using it for subsequent material preparation. All solutions and instruments that come into contact with MR-1 are sterilized in advance.

[0034] (2) Preparation of magnetic biochar;

[0035] Add 50-60 g / L of ferrous sulfate heptahydrate, 30-40 g / L of urea, 20-30 g / L of ascorbic acid and 8-15 g / L of dried pig manure to 100 mL of deionized water, and keep it at 80-85 ° C in an oven for 10-12 hours; then take out the solid matter and dry it at 80-85 ° C to constant weight; then put it into a tube furnace and heat it to 800-850 ° C at 5-10 ° C / min, and keep it at this temperature for 2-3 hours, then cool it naturally to room temperature and take it out; then wash it with deionized water several times, dry it at 80-85 ° C to constant weight, grind it and dry it for storage to obtain magnetic biochar.

[0036] The above-mentioned tube furnace pyrolysis is carried out in an inert gas environment, and the inert gas is preferably a nitrogen atmosphere.

[0037] (3) Magnetic biochar coupled with dissimilatory iron-reducing bacteria;

[0038] The bacterial strain enriched and cultured in step (1) is mixed with the magnetic biochar prepared in step (2), so that the bacterial strain is fully adsorbed on the surface of the magnetic biochar, thereby obtaining magnetic biochar-coupled dissimilatory iron-reducing bacteria.

[0039] Specifically, the bacterial strain and the magnetic biochar are added into a brown anaerobic bottle, and 40-50 mL of the mixed solution is added into the brown anaerobic bottle, and the bottle is horizontally shaken at 28-30° C. and 140-160 rpm.

[0040] The mixed solution contains 0.8-1.2 g / L (NH4)2SO4, 0.8-1.2 g / L NaCl, 0.1-0.4 mM MgSO4·7H2O, 0.1-0.15 g / L ZnCl2, 0.1-0.15 g / L CaCl2·2H2O, 3-5 mg / L vitamin B1 and 8-12 mM Pipes buffer as nutrients.

[0041] (4) antibiotic removal;

[0042] The magnetic biochar coupled with dissimilatory iron-reducing bacteria is fully contacted with the antibiotic wastewater to ensure that the antibiotics in the wastewater can be effectively removed.

[0043] For example, magnetic biochar coupled with dissimilatory iron-reducing bacteria and antibiotic wastewater can be added to a brown anaerobic bottle for reaction, and the reaction time is controlled to be 48-96 hours, preferably 72 hours. The antibiotics in the antibiotic wastewater include tetracycline and ciprofloxacin. While measuring the antibiotic concentration, the growth status of MR-1 and the Fe content in the solution can also be observed. 2+ content.

[0044] The present invention will be further described below with reference to specific embodiments.

[0045] Example 1

[0046] (1) All solutions and consumables that come into direct contact with the strains must be sterilized at high temperature in advance.

[0047] (2) Take out the MR-1 glycerol tube sealed at -80℃, resuscitate it at -20℃ and 4℃ respectively, then place it in the prepared LB medium, and culture it in a constant temperature water bath shaker at 28-30℃ and 140-160rpm. Subculture it when it reaches the logarithmic growth phase.

[0048] (3) Remove the MR-1 cells that have undergone one passage in step (2) when they reach the logarithmic growth phase and centrifuge them in a high-speed refrigerated centrifuge at 4000-6000 rpm for 3-5 minutes. Discard the supernatant. Pour in physiological saline, mix thoroughly, centrifuge in a high-speed refrigerated centrifuge under the same conditions, discard the supernatant, and repeat this process. Pour in physiological saline a final time and mix thoroughly to obtain the bacterial solution required for subsequent material preparation.

[0049] (4) Preparation of PM material. Add 50 g / L of ferrous sulfate heptahydrate, 40 g / L of urea, 30 g / L of ascorbic acid, and 8 g / L of dried pig manure to 100 mL of deionized water and keep it in an oven at 80°C for 10 h. Then take out the solid and dry it at 80°C to constant weight. Then put it in a tube furnace, maintain a nitrogen atmosphere, and heat it to 850°C at a rate of 10°C / min. Keep it at this temperature for 2 h, then cool it down to room temperature and take it out. Then wash it with deionized water several times, dry it at 80°C to constant weight, grind it, and dry it to obtain magnetic biochar (PM).

[0050] (5) Prepare a 40 mL solution containing 1.2 g / L (NH4)2SO4, 0.8 g / L NaCl, 0.1 mM MgSO4·7H2O, 0.15 g / L ZnCl2, 0.1 g / L CaCl2·2H2O, 5 mg / L vitamin B1, and 10 mM Pipes as nutrients. Add the bacterial solution prepared in step (3) and the PM prepared in step (4) to this solution. MR-1 is successfully loaded onto the PM surface by physical adsorption, as shown in FIG. Figure 1 As shown in Figure 2, the obtained material is PM@MR-1. At the same time, according to the characterization method, it was observed that the added Fe and N elements were successfully doped into PM@MR-1. Figure 2 shown.

[0051] Example 2

[0052] The preparation method is the same as that of Example 1, except that:

[0053] 60 g / L of ferrous sulfate heptahydrate, 30 g / L of urea, 20 g / L of ascorbic acid, and 15 g / L of dried pig manure were added to 100 mL of deionized water and incubated in an oven at 85°C for 12 hours. The solids were then removed and dried at 85°C to constant weight. The solids were then placed in a tube furnace under a nitrogen atmosphere and heated at 5°C / min to 800°C. The temperature was then maintained at this temperature for 3 hours, followed by natural cooling to room temperature before removal. The solids were then washed multiple times with deionized water, dried at 85°C to constant weight, ground, and stored dry to obtain magnetic biochar (PM).

[0054] A 50 mL solution containing 0.8 g / L (NH4)2SO4, 1.2 g / L NaCl, 0.4 mM MgSO4·7H2O, 0.1 g / L ZnCl2, 0.15 g / L CaCl2·2H2O, 3 mg / L vitamin B1 and 8 mM Pipes was prepared as nutrients.

[0055] Example 3

[0056] The preparation method is the same as that of Example 1, except that:

[0057] 55 g / L of ferrous sulfate heptahydrate, 30 g / L of urea, 20 g / L of ascorbic acid, and 10 g / L of dried pig manure were added to 100 mL of deionized water and incubated in an oven at 80°C for 10 hours. The solids were then removed and dried at 80°C to constant weight. The solids were then placed in a tube furnace under a nitrogen atmosphere and heated at a rate of 7°C / min to 850°C. The temperature was then maintained at this temperature for 3 hours, followed by natural cooling to room temperature before removal. The solids were then washed multiple times with deionized water, dried at 80°C to constant weight, ground, and stored dry to obtain magnetic biochar (PM).

[0058] A 50 mL solution containing 1.0 g / L (NH4)2SO4, 1.0 g / L NaCl, 0.4 mM MgSO4·7H2O, 0.15 g / L ZnCl2, 0.12 g / L CaCl2·2H2O, 5 mg / L vitamin B1 and 10 mM Pipes was prepared as nutrients.

[0059] Application Example 1

[0060] The PM, MR-1 and PM@MR-1 obtained in Example 1 were used to remove antibiotics from pig farming wastewater.

[0061] Removal experiment: 15 mg (0.3 g / L) PM, 10% (V, V) MR-1, and 15 mg (0.3 g / L) and 10% (V, V) PM@MR-1 were added to different pig farming wastewater (50 mL), and shaken at room temperature and pH 7.0 for 0.5, 1, 2, 4, 12, 24, 48, and 72 hours, respectively. The implementation process was detected at each time point using an ultraviolet spectrophotometer.

[0062] Removal performance evaluation: Figure 3 As shown in Figures (a) and (b), PM@MR-1 significantly improved antibiotic removal. For example, within 4 hours, PM@MR-1 achieved 60% and 33% removal rates for TC and CIP, respectively. In contrast, PM achieved only 28% and 20% removal rates for TC and CIP, respectively. MR-1 achieved even lower removal rates of 5% and 6%. This indicates that the combination of PM and MR-1 significantly improved both antibiotic removal rates and efficiency, suggesting a synergistic effect between MR-1 and PM.

[0063] Application Example 2

[0064] The PM@MR-1 prepared in Example 1 was used to remove antibiotics from pig farming wastewater under different antibiotic concentration conditions.

[0065] The antibiotic removal experiment is similar to the process of removing antibiotics from pig farming wastewater in Application Example 1. The difference is that the concentrations of TC and CIP are 0.15 mg (3 mg / L), 0.25 mg (5 mg / L), 0.5 mg (10 mg / L), and 1 mg (20 mg / L), respectively.

[0066] Removal performance evaluation: passed Figure 4 In (a) and (b), it can be observed that under conditions of lower antibiotic concentrations, PM@MR-1 has a higher removal rate of antibiotics. Taking TC as an example, at a concentration of 3 mg / L, the removal rate of TC in the reaction system reaches 70%, which is consistent with the rule that low-concentration pollutants are more easily removed. However, the same trend was not observed in the removal process of CIP. Figure 4 As shown in (b), when the CIP concentration increased from 3 mg / L to 5 mg / L, the removal rate decreased. However, when the concentration continued to increase to 10 mg / L, the CIP removal rate increased again compared with 5 mg / L. Moreover, at 20 mg / L, the overall CIP removal rate was higher than that at 5 mg / L. 600 value( Figure 4 (c) Analysis: OD of MR-1 at 3 mg / L and 5 mg / L 600 The values ​​were high at the beginning of the reaction, but decreased significantly over time, indicating that low concentrations of antibiotics could not continuously provide sufficient nutritional support for MR-1, especially in the middle and late stages of the reaction. In addition, although the removal rates of TC and CIP were relatively low at concentrations of 10 mg / L and 20 mg / L, the actual removal amounts were still considerable. Figure 4 As shown in (c), under conditions of higher antibiotic concentrations, the OD 600 The value was not at a low level, indicating that its growth was not significantly inhibited. This phenomenon shows that the introduction of PM enables the system to maintain activity and effectively remove antibiotics over a wide range of antibiotic concentrations.

[0067] Application Example 3

[0068] The PM@MR-1 prepared in Example 1 was used to remove antibiotics from pig farming wastewater under different pH conditions.

[0069] The antibiotic removal experiment was similar to the process of removing antibiotics from pig farming wastewater in Application Example 2. The difference was that the concentrations of TC and CIP were 0.5 mg (10 mg / L), and the pH conditions were changed to 5, 6, and 8.

[0070] Removal performance evaluation: Figure 5As shown in (a) and (b), a neutral pH environment is most conducive to the synergistic effect of PM and MR-1. During the TC removal process, the TC removal rate decreased slightly under weakly acidic conditions (pH = 5, 6), while the TC removal rate decreased significantly under weakly alkaline conditions (pH = 8). It is known that the pKa values ​​of TC are 3.3, 7.7, and 9.7. In the pH range of 7.7 to 9.7, TC mainly exists in the form of negatively charged ions. Combined with the Zeta potential of PM ( Figure 6 ) analysis shows that at pH 8, the PM surface is negatively charged, making it difficult for negatively charged TC to be adsorbed by PM to the material itself, thereby limiting the role of MR-1 on the PM surface. For the removal of CIP, its pKa value is 6.1 and 8.7. When the pH is less than 6.1, CIP exists in the form of positively charged ions, while the PM surface is negatively charged. Therefore, PM can effectively adsorb CIP to itself, and at the same time, MR-1 on the PM surface can also play a role. This mechanism explains Figure 5 Phenomenon observed in (b): Under conditions of pH 5 and 6, the CIP removal rate is significantly higher than that at pH 8, and even the removal efficiency at pH 5 is comparable to that under neutral conditions (pH 7).

[0071] At the same time, by analyzing the OD of MR-1 600 Value (such as Figure 5 Figure (c) shows that under weak acid and weak base conditions, the cell concentration of MR-1 is low and the growth stability is poor, especially at pH 8. This result also proves that a neutral environment is most conducive to the stable operation of the PM@MR-1 synergistic system.

[0072] Application Example 4

[0073] The PM@MR-1 prepared in Example 1 was used to remove antibiotics from pig farming wastewater under different PM dosage conditions.

[0074] The antibiotic removal experiment was similar to the process of removing antibiotics from pig farm wastewater in Application Example 2. The differences were that the pH conditions of TC and CIP were 7, and the PM dosage was changed to 5 mg (0.1 g / L), 25 mg (0.5 g / L), and 50 mg (1 g / L).

[0075] Removal performance evaluation: Figure 7 As shown in (a) and (b), with the increase of PM dosage, the removal rates of TC and CIP both showed an upward trend. This phenomenon may be due to the increase in PM dosage, which increased the contact between MR-1 and PM, thereby enhancing the synergistic effect between the two. In addition, the role of PM in the removal of antibiotics cannot be ignored: PM itself has a strong adsorption capacity, and the increase in its dosage directly improves the adsorption and removal effect of antibiotics. By observing the OD values ​​of different systems, the removal rate of TC and CIP increased significantly. 600value( Figure 7 (c) found that the addition of PM increased the biomass of MR-1, and the PM dosage was positively correlated with MR-1 growth. This suggests that PM has a good protective effect on MR-1, promoting its growth and maintaining metabolic activity.

[0076] Application Example 5

[0077] When PM@MR-1 prepared in Example 1 was used to remove antibiotics from piggery wastewater under different conditions, the Fe 2+ Perform the measurement.

[0078] Performance evaluation: In the process of exploring different influencing factors, the Fe 2+ The concentration changes, such as Figure 8 The results show that after the reaction, a certain concentration of Fe 2+ .Fe 2+ The concentration change trend is consistent with the research results and experimental phenomena: under different PM dosage conditions, as the dosage increases, the final Fe 2+ The concentration of PM showed an increasing trend, which indicates that higher concentrations of PM can provide more contact sites for MR-1, thereby promoting the Fe 3+ Under different antibiotic concentration conditions, the 3 mg / L group showed the highest Fe 2+ The results are consistent with the optimal removal rate under 3 mg / L conditions, and also indicate that low concentration antibiotic environment has a weaker inhibitory effect on MR-1. In addition, under different pH conditions, neutral environment is more conducive to Fe 2+ This phenomenon is consistent with the results of previous studies.

[0079] Application Example 6

[0080] The Fe element XPS characterization of the PM and PM@MR-1 materials prepared in Example 1 was analyzed to observe the changes in the Fe valence state during the reaction.

[0081] Performance evaluation: Figure 9 The XPS spectrum of Fe element shows that the spin-orbit splitting peaks of two valence states of iron (2p 3 / 2 and 2p 1 / 2 ) and Fe 3+ The accompanying peak of Fe in PM 2+ The two peaks are located at 710.61eV (Fe 2+ 2p 3 / 2 ) and 724.25eV(Fe 2+ 2p 1 / 2 ) at the other three Fe3+ The relevant peaks are located at: 713.21eV (Fe 3+ 2p 3 / 2 )、727.12eV(Fe 3+ 2p 1 / 2 ) and 718.76eV(Fe 3+ After MR-1 was added and participated in the reaction, the binding energy of Fe 2p shifted slightly to the direction of high binding energy, among which Fe 2+ 2p 3 / 2 and Fe 2+ 2p 1 / 2 The corresponding peak develops towards a larger trend. In addition, Fe 2+ The proportion of Fe increased from 45.02% to 53.7%, 3+ The proportion dropped from 54.98% to 46.3%.

[0082] This result is consistent with the Fe solution before and after the reaction in Application Example 5. 2+ The combination of the concentration changes indicates that during the removal of antibiotics, the valence of iron changes, which is manifested as Fe 3+ Fe 2+ It is known that MR-1 has excellent respiration and reduction of Fe 3+ Ability, under anaerobic conditions Fe 3+ As an electron donor for MR-1, it provides electrons. Through intracellular electron transfer, it can transfer electrons to the reductase at the intracellular terminal, and then use the antibiotic as an electron acceptor to promote the removal of antibiotics by substances such as reductase. Therefore, it can be confirmed that MR-1 can successfully utilize Fe on PM. 3+ Electron transfer is carried out to jointly promote the removal of TC and CIP. At the same time, this characterization result is consistent with the Fe 2+ The concentration change results were consistent, proving the authenticity of this pathway.

[0083] Parts not described in the above methods can be achieved by adopting or drawing on existing technologies.

[0084] The above description is only for the preferred embodiments of the present invention and does not limit the present invention. Any improvements and changes made by those skilled in the art without departing from the creative thinking of the present invention should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria, characterized in that The following steps are involved: (1) Select bacterial strains and perform enrichment culture; Shewanella Oneida was used as the bacterial strain, which was inoculated into LB liquid medium, aerobically enriched in a constant temperature water bath shaker, and then subcultured; (2) Preparation of magnetic biochar; (3) Magnetic biochar coupled with dissimilatory iron-reducing bacteria; The bacterial strain enriched and cultured in step (1) is mixed with the magnetic biochar prepared in step (2), so that the bacterial strain is fully adsorbed on the surface of the magnetic biochar, thereby obtaining magnetic biochar-coupled dissimilatory iron-reducing bacteria; (4) antibiotic removal; Magnetic biochar coupled with dissimilatory iron-reducing bacteria is fully contacted with antibiotic wastewater to remove antibiotics from the wastewater.

2. The method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria according to claim 1, characterized in that: In step (1), the glycerol tube containing Shewanella Oneida is inoculated into LB liquid culture medium, and the aerobic enrichment time is controlled to be 10-14 hours, and the subculture time is controlled to be 7-10 hours.

3. The method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria according to claim 2, characterized in that: LB liquid culture inoculated with Shewanella Oneida was shaken horizontally at 28-30°C and 140-160 rpm; The subculture process is as follows: take out the Oneida Shewanella that has reached the logarithmic growth phase, first remove the supernatant by centrifuge, then add physiological saline and mix the solution, then centrifuge to remove the supernatant, repeat the above operation multiple times, and finally add physiological saline for the last time and mix the bacterial solution before use.

4. The method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria according to claim 1, characterized in that: In step (2), the preparation steps of magnetic biochar are as follows: Add 50-60 g / L of ferrous sulfate heptahydrate, 30-40 g / L of urea, 20-30 g / L of ascorbic acid and 8-15 g / L of dried pig manure to 100 mL of deionized water, and keep it at 80-85 ° C in an oven for 10-12 hours; then take out the solid matter and dry it at 80-85 ° C to constant weight; then put it into a tube furnace and heat it to 800-850 ° C at 5-10 ° C / min, and keep it at this temperature for 2-3 hours, then cool it naturally to room temperature and take it out; then wash it with deionized water several times, dry it at 80-85 ° C to constant weight, grind it and dry it for storage to obtain magnetic biochar.

5. The method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria according to claim 1, characterized in that: In step (3): the bacterial strain and the magnetic biochar are added to a brown anaerobic bottle, and the mixed solution is added to the brown anaerobic bottle, and the bottle is horizontally shaken at 28-30° C. and 140-160 rpm.

6. The method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria according to claim 5, characterized in that: The mixed solution contains 0.8-1.2 g / L (NH4)2SO4, 0.8-1.2 g / L NaCl, 0.1-0.4 mM MgSO4·7H2O, 0.1-0.15 g / L ZnCl2, 0.1-0.15 g / L CaCl2·2H2O, 3-5 mg / L vitamin B1 and 8-12 mM Pipes buffer.

7. The method for removing antibiotics by coupling magnetic biochar with dissimilatory iron-reducing bacteria according to claim 1, characterized in that: In step (4): adding magnetic biochar coupled with dissimilatory iron-reducing bacteria and antibiotic wastewater into a brown anaerobic bottle for reaction, and controlling the reaction time to be 48-96 hours; the antibiotics in the antibiotic wastewater include tetracycline and ciprofloxacin.

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