Iron oxide / black carbon compound for enhancing degradation of antibiotics by anaerobic microorganisms, preparation method and application

Abstract

The invention provides an iron oxide / black carbon compound for strengthening anaerobic microorganisms to degrade antibiotics as well as a preparation method and application of the iron oxide / black carbon compound. According to the iron oxide / black carbon composite material, sawdust is used as a raw material to prepare black carbon, the black carbon is presoaked in an iron salt solution, then oxygen-limited pyrolysis is carried out, iron oxide is evenly anchored in a black carbon pore channel structure, and the iron oxide / black carbon composite material with high-dispersity iron active sites is obtained. The iron oxide / black carbon compound prepared by the preparation method disclosed by the invention has a synergistic effect with anaerobic sludge, and the adsorption, activation and degradation capabilities of microorganisms on antibiotics can be remarkably improved, so that the anaerobic degradation process of the antibiotics is accelerated, and excellent reactivity and stability are shown. Compared with a control system without materials, the method has the advantages that the antibiotic removal rate and the COD degradation efficiency can be obviously improved, and the electron transfer capacity and the anaerobic metabolism activity of the system are enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, environmental microorganism and water pollution control, and particularly relates to an iron oxide / charcoal compound for enhancing anaerobic microbial degradation of antibiotics, a preparation method and application thereof, which is suitable for biological enhanced degradation of antibiotics in wastewater treatment, contaminated groundwater remediation and actual engineering systems. BACKGROUND

[0002] As a typical emerging pollutant, antibiotics exist widely in municipal wastewater, livestock and poultry breeding wastewater and hospital drainage. Most of the antibiotics have the characteristics of stable structure, difficult biodegradation, easy enrichment and easy induction of drug resistance spread. The continuous accumulation of antibiotics in the environment not only inhibits microbial metabolism, changes the community structure, but also promotes the spread of drug resistance genes, which poses a significant threat to ecological system safety and public health. Although the problem of antibiotic pollution has been concerned, the emission monitoring standard, treatment process system and engineering treatment means are still significantly lagging behind, and there is a long-term lack of treatment measures that can effectively deal with the environmental risk of antibiotics.

[0003] In traditional wastewater treatment, conventional activated sludge or anaerobic digestion systems are difficult to efficiently degrade antibiotics, mainly due to the stable structure of antibiotic molecules, inhibited microbial metabolism, and decreased efficiency of electron transfer chain. In recent years, carbon material assisted biodegradation has become a research hotspot. Black carbon (BC) has electrical conductivity, rich pore structure and surface oxygen-containing functional groups, and can be used as a microbial electron transfer promoter. However, pure black carbon is still limited in terms of electron transport capacity and reaction rate improvement. Iron oxides (such as Fe3O4 and γ-Fe2O3) have high electron activity, and can be used as electron relay or participants in iron cycle coupling processes in anaerobic environments, and can also adsorb antibiotics and provide catalytic sites. However, the use of iron oxides has problems such as agglomeration, rapid settling, and low contact efficiency with microorganisms.

[0004] Therefore, it is of great scientific significance and engineering value to develop a catalyst that can significantly improve the microbial degradation rate and enhance the removal efficiency of antibiotics. SUMMARY

[0005] To solve the technical problems existing in the prior art, the application provides an iron oxide / charcoal compound for strengthening anaerobic microbial degradation of antibiotics, a preparation method and application thereof in promoting efficient degradation of antibiotics by anaerobic microorganisms. The iron oxide / charcoal compound promotes electron transfer of microorganisms, adsorption and enrichment of antibiotics, and iron cycle promotion, and improves the biodegradation efficiency, reaction rate and long-term stability of the system to antibiotics. The iron oxide / charcoal compound has high specific surface area, a conductive network and reversible Fe(II) / Fe(III) cycle capacity, greatly promotes mass transfer of pollutants, distribution of electron flow and recovery of microbial activity, and thus strengthens microbial degradation of antibiotics. Meanwhile, a sludge system with stable operation and a regulation mechanism are selected, and a systematic application method for antibiotic biodegradation is proposed by adopting a synergistic mechanism of iron-carbon-microorganisms.

[0006] The technical problems solved by the application are realized by adopting the following technical solutions: A preparation method of an iron oxide / charcoal compound for strengthening anaerobic microbial degradation of antibiotics, comprising the following steps: S1, impregnating wood chips with an iron salt solution to obtain an iron oxide / charcoal compound precursor solution; S2, performing solid-liquid separation on the obtained iron oxide / charcoal compound precursor solution and performing first heat treatment to obtain an iron oxide / charcoal compound precursor; S3, performing second heat treatment on the iron oxide / charcoal compound precursor to obtain an iron oxide / charcoal compound, and performing washing, drying and grinding on the iron oxide / charcoal compound after the second heat treatment to obtain the iron oxide / charcoal compound.

[0007] Further, in step S1, the impregnation treatment is that 10-30 g of wood chip samples are immersed in 100-400 mL of Fe(NO3)3·9H2O solution with a concentration of 0.1-1.0 mol / L, and then stirred at 40-80 ℃ and 200-400 rpm for 4-8 h. Preferably, 20 g of wood chip samples are immersed in 250 mL of Fe(NO3)3·9H2O solution with a concentration of 0.5 mol / L, and then stirred at 60 ℃ and 300 rpm for 6 h.

[0008] The wood chips are lignocellulosic biomass containing relatively high lignin or aromatic precursors, and are beneficial to form high carbon yield and a conductive skeleton. Preferably, the wood chips are pine wood chips.

[0009] Further, in step S2, the first heat treatment is drying at 100-110 ℃ for 6-10 h. Further, in step S3, the second heat treatment is: under the protection of inert gas, the temperature is raised to 700-800 DEG C at a rate of 8-12 DEG C / min, and kept constant for 0.5-1.5 h. In a preferred scheme, the second heat treatment is: under the protection of inert gas, the temperature is raised to 750 DEG C at a rate of 10 DEG C / min, and kept constant for 1 h. The temperature and time control in the process is extremely critical, if the temperature is too low, it is not conducive to carbonization, resulting in poor conductivity; if the temperature is too high, it is easy to lead to the collapse of the pore results; and if the heat treatment time is too short, it is not conducive to carbonization; if the heat treatment time is too long, it will lead to the secondary reaction of biochar, forming tar and other by-products.

[0010] Further, in step S3, the washing treatment is: washed with anhydrous ethanol and pure water respectively until neutral.

[0011] The first heat treatment is to remove free water and part of the bound water in the sawdust and impregnation system, promote the uniform loading and preliminary fixation of iron salt on the pores and surface of sawdust, prevent the migration, agglomeration or structure damage of iron salt due to rapid water evaporation in the subsequent high temperature pyrolysis process, thereby improving the dispersion and structural stability of iron oxide in the black carbon matrix. The second heat treatment is to carbonize the sawdust into black carbon skeleton with high conductivity and porous structure, promote the thermal decomposition and phase change of iron salt, generate iron oxide stably loaded on the surface of black carbon, realize the close compounding between iron oxide and black carbon, and build the interface structure conducive to electron transfer and iron cycle, thereby providing a functional basis for subsequent strengthening of anaerobic microbial electron transfer and antibiotic degradation.

[0012] The application further provides an iron oxide / black carbon composite for strengthening anaerobic microbial degradation of antibiotics, which is prepared by the above method.

[0013] The application further provides application of the iron oxide / black carbon composite prepared by the above method in wastewater treatment by anaerobic microorganisms, and the application method is as follows: anaerobic sludge is added into wastewater to be treated, and stirred to obtain a stable sludge system; The iron oxide / black carbon composite is mixed with the stable sludge system to obtain a material-sludge mixed system, and stirred to remove antibiotics in the wastewater.

[0014] Further, the anaerobic sludge is active sludge which is pollution-free, contains anaerobic bacteria, and can quickly start the anaerobic digestion reaction of sludge. The introduction of the anaerobic sludge is to provide an anaerobic microbial community with complete metabolic function, and to cooperatively build a biological reaction system with efficient electron transfer and iron cycle coupling with the iron oxide / black carbon composite, thereby improving the biological degradation efficiency of antibiotics and the stability of the system.

[0015] Further, the total suspended solids concentration in the stable sludge system is 10-40 g / L, and the volatile suspended solids concentration is 5-20 g / L. The stable sludge system refers to that, in the continuous operation process of the anaerobic reaction system, the key operation parameters tend to be stable, including but not limited to the organic matter removal performance, the gas production rate, and the system pH, and the like, which are less fluctuated in continuous multiple operation cycles, indicating that the microbial community structure and metabolic activity have basically adapted to the reaction environment and entered the stable operation stage.

[0016] Further, the addition amount of the iron oxide / charcoal compound in the mixed system is 1.5-2.5 g / L; in the preferred scheme, the addition amount of the iron oxide / charcoal compound is 2 g / L.

[0017] Further, the material-sludge mixed system is oscillated at 25-35 DEG C under the constant temperature and 100-200 rpm, so as to fully contact and remove the antibiotics.

[0018] Further, the pollutants in the wastewater are antibiotic pollutants, specifically sulfadimethoxine (SDM).

[0019] Further, the application is suitable for the biological enhanced degradation of antibiotics in wastewater treatment, contaminated groundwater remediation, and actual engineering systems.

[0020] The application has the following beneficial effects: (1) The application provides an iron oxide / charcoal composite for strengthening anaerobic microbial degradation of antibiotics, which is prepared by impregnation of wood chips and composite preparation through limited oxygen pyrolysis. The iron oxide / charcoal composite preferably uses pine wood chips as a carbon source, and has the advantages of wide raw material sources, low price, simple and controllable preparation process, and obvious cost advantage. The charcoal derived from pine wood chips has a developed microporous structure and adjustable oxygen-containing functional groups, and forms a dense contact interface with the iron oxide during in-situ loading, thereby constructing a composite material rich in Fe-O-C bond structures. The iron oxide in the composite system is in a highly dispersed state at the nanoscale, can provide a reversible Fe(III) / Fe(II) cyclic electron pool, and the charcoal skeleton has excellent conductivity and adsorption capacity, so that the composite has the functions of pollutant enrichment, electron transfer and microbial carrier. The structural characteristics significantly promote the efficient migration of electrons between iron cycle and microbial metabolism in the anaerobic system, accelerate the primary rupture and deep degradation of antibiotics, and effectively alleviate the inhibition effect of antibiotics on microorganisms. Experimental results show that the adsorption removal rate of the iron oxide / charcoal composite of the application to pollutants can reach more than 95% within 5 min; and the degradation rate of microorganisms to antibiotic pollutants can be significantly improved under anaerobic conditions, and after the material-sludge system is stabilized, the removal rates of antibiotics and COD can be stably maintained at more than 55% and 90%, respectively. The pollutant removal effect after adding the material is 1.9-4.6 times that of the system without adding the material, and the COD removal rate is increased by 12-46% compared with the system without adding the material, which fully proves that the composite material has a significant strengthening effect on microbial activity, metabolic intensity and system stability. At the same time, the interface structure formed between the iron oxide and the charcoal can inhibit the loss of iron ions during operation, promote the recycling of iron species in the reactor, and make the composite material still maintain high electron transfer capacity and structural stability during long-term operation.

[0021] (2) The preparation method of the iron oxide / charcoal composite disclosed by the application controls the pyrolysis speed, pyrolysis temperature, carbonization time and post-treatment conditions, so that the obtained composite material has suitable pore structure, functional group distribution and iron phase state at the same time, realizes the continuous and synergistic process of rapid enrichment-activation-biodegradation of antibiotics, and has the advantages of mild reaction conditions, easy control of process nodes, high stability of material preparation, and good engineering application potential.

[0022] (3) The application of the iron oxide / black carbon composite in sewage treatment and anaerobic digestion system can significantly enhance the electron supply and acceptance capacity of anaerobic microorganisms, improve the degradation efficiency of antibiotic emerging pollutants, reduce the toxicity inhibition of antibiotics on microbial communities, and realize efficient conversion of organic pollutants into low-toxic or even harmless substances. The method has the advantages of simple process, low operation cost, strong material stability and high treatment efficiency, and can be used for antibiotic wastewater treatment, livestock and poultry wastewater pretreatment, sludge anaerobic digestion intensification and other multi-scenario applications, and has significant engineering value and broad application prospect.

[0023] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification. The illustrations are shown to explain the present application and are not intended to be an undue limitation thereon. In the drawings: Figure 1 A curve graph showing the removal effect of the materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 in Example 1 on SDM in synthetic wastewater with time; Figure 2 A curve graph showing the removal efficiency of anaerobic microorganisms on SDM with time under the action of the materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 respectively in Example 2; Figure 3 A curve graph showing the removal efficiency of anaerobic microorganisms on COD with time under the action of the materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 respectively in Example 3. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application will be further described below in conjunction with specific embodiments, but the protection scope of the present application is not limited thereby. The raw materials and instruments used in the following examples are commercially available.

[0026] Example 1 The iron oxide / black carbon composite described in this embodiment has a preparation method comprising the following steps: S1, using pine sawdust as iron modified black carbon raw material, the pine sawdust is treated by immersion: 20 g of pine sawdust is immersed in 250 mL of Fe(NO3)3·9H2O solution with a concentration of 0.5 mol / L, and stirred in a constant temperature magnetic stirrer at 60℃ and 300 rpm for 6 h.

[0027] S2. After the impregnation treatment is completed, the obtained material is subjected to solid-liquid separation, and the separated solid is dried in an oven at 105℃ for 8 hours.

[0028] S3. Place the dried wood chips in a tube furnace for heat treatment: under Ar gas protection, heat to 750℃ at a heating rate of 10℃ / min, and maintain the temperature for 60 min.

[0029] After heat treatment, the obtained material was washed with anhydrous ethanol and distilled water until the washing solution was neutral, and then dried in an oven at 60 °C for 12 h to obtain the iron oxide / black carbon composite, abbreviated as Fe-BC.

[0030] Example 2 The iron oxide / carbon black composite described in this embodiment is prepared by the following steps: S1. Using pine wood chips as the raw material for iron-modified black carbon, the pine wood chips were impregnated: 10 g of pine wood chips were impregnated in 250 mL of Fe(NO3)3·9H2O solution with a concentration of 0.1 mol / L, and stirred for 4 h in a constant temperature magnetic stirrer at 40℃ and 200 rpm.

[0031] S2. After the impregnation treatment is completed, the obtained material is subjected to solid-liquid separation, and the separated solid is dried in an oven at 100℃ for 6 hours.

[0032] S3. Place the dried wood chips in a tube furnace for heat treatment: under Ar gas protection, heat to 700℃ at a heating rate of 8℃ / min and maintain the temperature for 1.5 h.

[0033] After heat treatment, the obtained material was washed with anhydrous ethanol and distilled water until the washing solution was neutral, and then dried in an oven at 60 °C for 12 h to obtain the iron oxide / black carbon composite, abbreviated as Fe-BC.

[0034] Example 3 The iron oxide / carbon black composite described in this embodiment is prepared by the following steps: S1. Using pine wood chips as the raw material for iron-modified black carbon, the pine wood chips were impregnated: 30 g of pine wood chips were impregnated in 250 mL of Fe(NO3)3·9H2O solution with a concentration of 1 mol / L, and stirred for 8 h in a constant temperature magnetic stirrer at 80℃ and 400 rpm.

[0035] S2. After the impregnation treatment is completed, the obtained material is subjected to solid-liquid separation, and the separated solid is dried in an oven at 110℃ for 10 h.

[0036] S3. Place the dried wood chips in a tube furnace for heat treatment: under Ar gas protection, heat to 800℃ at a heating rate of 12℃ / min, and maintain the temperature for 30 min.

[0037] After heat treatment, the obtained material was washed with anhydrous ethanol and distilled water until the washing solution was neutral, and then dried in an oven at 60 °C for 12 h to obtain the iron oxide / black carbon composite, abbreviated as Fe-BC.

[0038] Comparative Example 1 A black carbon material, the preparation method of which includes the following steps: Pine wood chips were used as the raw material for black charcoal. The wood chips were placed in a tube furnace for heat treatment: heated to 750 ℃ ​​at a heating rate of 10 ℃ / min and held at a constant temperature for 60 min.

[0039] After heat treatment, the obtained material is washed with anhydrous ethanol and distilled water until the washing solution is neutral, and then dried in an oven at 60 °C for 12 h to obtain black carbon, abbreviated as BC.

[0040] Comparative Example 2 An iron oxide material, the preparation method of which includes the following steps: S1. Add 5.56022 g FeSO4·7H2O and 10.8114 g FeCl3·6H2O to 40 mL of oxygen-free water that has been pre-treated with N2 for 10 min to remove oxygen. Mix under ultrasonic conditions to fully dissolve the two iron salts and form a uniform, transparent, yellow-green solution.

[0041] After ultrasonic treatment, 12 mL of ammonia water is added dropwise to the iron salt solution.

[0042] S2. Place the resulting mixture in a water bath at 80 °C and stir magnetically for 5 min. After stirring magnetically for 5 min, add 12 mL of anoxic water dropwise to the solution, and then stir magnetically for 2 h.

[0043] S3. After magnetic stirring, the system was allowed to cool naturally to room temperature, centrifuged, and the resulting solid was washed alternately with anhydrous ethanol and distilled water until the washing liquid was neutral. Then it was dried in an oven at 60 °C for 12 h to obtain iron oxide, abbreviated as Fe3O4.

[0044] Application Example 1: Two g each of Fe-BC, BC, and Fe3O4 prepared in Example 1, Comparative Example 1, and Comparative Example 2 were added to 250 mL of synthetic wastewater. The pollutant in the synthetic wastewater was sulfadimethylpyrimidine (SDM), and the adsorption performance of the material of the present invention was tested. The composition of the synthetic wastewater is shown in Table 1 and was used to simulate wastewater treatment.

[0045] Table 1. Composition of Synthetic Wastewater Element Concentration [C6H 12 O6]]> 2.1 g / L [C2H3NaO2] 1.4 g / L NH4CI 550 mg / L KH2PO4 78 mg / L K2HPO4 63 mg / L NaHCO3 3 g / L CaCl2 8 mg / L MgCl2.6H2O 27 mg / L Trace element stock solution 0.5 mL / L Contaminants 28 mg / L The composition of the trace element reserve solution in the synthetic wastewater is shown in Table 2: Table 2 Composition of Trace Element Stock Solution Element Concentration FeCl3-6H2O 1.5 g / L ZnSO4·7H2O 0.12 g / L [CuSO4·5H2O] 0.03 g / L CoCl2-6H2O 0.15 g / L MnCl2.4H2O 0.12 g / L H3BO3 0.15 g / L KI 0.18 g / L Na2MoO4·2H2O 0.06 g / L EDTA 10 g / L Figure 1 The graphs show the time-varying effects of the materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 on the removal of SDM from synthetic wastewater. Figure 1 As shown in the experimental results, the degradation efficiency of SDM in the synthetic wastewater with added BC reached 56% within 12 hours, but decreased to 18% after 24 hours, a decrease of 38% overall. This is because pollutants adsorbed on the material surface desorb over time. Therefore, the adsorption effect of BC on SDM is extremely unstable. Fe3O4 showed a degradation efficiency of only 9% for SDM after 24 hours of adsorption, indicating unsatisfactory adsorption. However, the composite Fe-BC, prepared by combining Fe3O4 and BC, almost completely removed SDM from the synthetic wastewater after 5 minutes of adsorption, and the adsorption effect was extremely stable. Therefore, it is demonstrated that Fe-BC, the composite of Fe3O4 and BC, significantly improves the adsorption effect of SDM compared to Fe3O4 and BC alone.

[0046] Application Example 2: First, anaerobic sludge is added to the wastewater to be treated and stirred evenly to obtain a stable sludge system. Then, the iron oxide / black carbon composite is mixed with the stable sludge system to obtain a material-sludge mixture system. After stirring evenly, the wastewater treatment can be simulated.

[0047] Specifically, the anaerobic sludge contains a large number of functional microorganisms (mainly methanogens and hydrolytic acidifying bacteria), and is free from significant toxic and harmful substance contamination (such as heavy metals and high-concentration organic solvents), making it an activated sludge capable of rapidly initiating the anaerobic digestion reaction. The total suspended solids concentration in the stably operating sludge system is 10–40 g / L, and the volatile suspended solids concentration is 5–20 g / L. The composition of the synthetic wastewater used is shown in Table 1.

[0048] This experiment consisted of four groups. 100 mL of anaerobic sludge and 250 mL of synthetic wastewater were added to each of the four reactors. The pollutant in the synthetic wastewater was sulfadiazine (SDM). One group served as a blank control group without any added materials. The other reactors were added with 2 g of Fe-BC, BC, and Fe3O4 prepared in Example 1, Comparative Example 1, and Comparative Example 2, respectively. The effects of different materials on the anaerobic biodegradation of SDM were further tested. The experimental results are shown below. Figure 2As shown.

[0049] Depend on Figure 2 As shown, materials were added to the experimental group after the reactor reached stability on day 15 of operation. Figure 2 As can be seen, the degradation efficiency of the control group remained almost unchanged at 26% after day 18. In the experimental groups with added materials, the degradation efficiency of the BC and Fe3O4 groups only increased slightly after the addition of materials, remaining at approximately 31% and 36%, respectively. In contrast, the enhancement effect of Fe-BC was the most significant. After the addition of materials on day 15, its SDM removal rate rapidly increased to 81% on day 18, which was better than other groups. However, starting from day 21, the SDM removal rate of the Fe-BC group decreased from its peak and stabilized at approximately 59%, remaining relatively constant during the subsequent operation period (up to day 60). This trend is closely related to the excellent adsorption performance of Fe-BC and its synergistic effect with microorganisms. Example 4 has demonstrated that Fe-BC has a significant adsorption effect on SDM, so after the material is added, it can rapidly enrich and remove a large amount of pollutants in a short time, resulting in a significant increase in the initial removal rate. As the adsorption sites gradually fill up and adsorption saturation occurs, the removal efficiency decreases accordingly, but the Fe-BC group can still maintain a much higher SDM removal rate than the control group for a long time, which is related to its continuous promotion of the anaerobic degradation process. Fe-BC possesses excellent electrical conductivity and abundant oxygen-containing functional groups on its surface, which can promote electron transfer within the sludge system, enhance microbial activity, and strengthen the substrate utilization capacity of key anaerobic bacteria. Simultaneously, the dispersed iron oxides in the material can undergo reversible valence state changes under anaerobic conditions, forming a stable iron cycle. This cycle serves as an additional electron acceptor pathway, alleviating the inhibitory effect of antibiotics on microbial metabolism, and can further participate in pollutant transformation after reduction to Fe(II). This continuously provides electronic regulation space for the microbial degradation process, ensuring that the biodegradation of SDM remains stable and at a high level throughout the entire operating cycle, with a removal rate consistently significantly higher than other experimental groups.

[0050] Application Example 3: This experiment consisted of four groups. 100 mL of anaerobic sludge and 250 mL of synthetic wastewater were added to each of the four reactors. The pollutant in the synthetic wastewater was sulfadiazine (SDM). One group served as a blank control without any added materials. The remaining reactors were added with 2 g of Fe-BC, BC, and Fe3O4 prepared in Example 1, Comparative Example 1, and Comparative Example 2, respectively. The effects of different materials on COD removal were further tested, and the experimental results are shown below. Figure 3 As shown.

[0051] Depend on Figure 3It can be seen that the COD removal rate of the control group increased slowly throughout the operation, reaching 54% at the end of 60 days. In the experimental group with added BC, the COD removal rate increased from 28% to 43% on day 18, but the long-term removal effect was similar to that of the control group. In contrast, the Fe3O4 and Fe-BC groups showed a more significant enhancing effect. In the Fe3O4 group, the COD removal rate rose to 62% on day 18 and continued to increase in subsequent operations, reaching 98% on day 60. The Fe-BC group performed even better, with a COD removal rate of 70% on day 18 and approximately 98% on day 45, significantly earlier than the Fe3O4 group and also significantly better than the other two groups. The above results indicate that Fe-BC, due to its combination of the electronic activity of iron oxides and the conductive structure of carbon, has a stronger synergistic effect in promoting microbial substrate utilization and electron transfer, thus exhibiting the best COD removal capacity throughout the operation. The experimental effects of the materials prepared in Examples 2 and 3 under the same conditions are similar to those in Example 1, and will not be repeated here.

[0052] Testing the effects of different materials on COD removal is used to observe the overall removal of organic matter in the anaerobic system. This not only helps determine the stability of the reactor operation but also evaluates the metabolic activity of anaerobic microorganisms and the overall health of the system. Furthermore, by comparing the changes in COD before and after material addition, the impact of the iron oxide / carbon composite on the metabolic processes of anaerobic microorganisms and the stability of the system can be further analyzed.

[0053] In summary, this invention provides an iron oxide / carbon composite for enhancing the degradation of antibiotics by anaerobic microorganisms, its preparation method, and its application. The iron oxide / carbon composite is prepared by using pine sawdust as raw material to produce carbon, which is then pre-impregnated in an iron salt solution followed by oxygen-limited pyrolysis. This process achieves uniform anchoring of iron oxides within the porous structure of the carbon, resulting in an iron oxide / carbon composite material with highly dispersed iron active sites. The iron oxide / carbon composite prepared by this invention synergistically enhances the adsorption, activation, and degradation capabilities of microorganisms for antibiotics when used with anaerobic sludge, thereby accelerating the anaerobic degradation process and exhibiting excellent reactivity and stability. Compared to the control system without added materials, the method of this invention significantly improves antibiotic removal rate and COD degradation efficiency, and enhances the system's electron transport capacity and anaerobic metabolic activity. This method is simple, uses widely available materials, and is suitable for large-scale application, providing an efficient and sustainable technical approach for the biodegradation of emerging pollutants such as antibiotics.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an iron oxide / charcoal composite for enhancing anaerobic microbial degradation of antibiotics, comprising the following steps: S1, impregnating wood chips with a ferric salt solution to obtain an iron oxide / charcoal composite precursor solution; S2, performing solid-liquid separation on the obtained iron oxide / charcoal composite precursor solution and performing a first heat treatment to obtain an iron oxide / charcoal composite precursor; S3, performing a second heat treatment on the iron oxide / charcoal composite precursor to obtain an iron oxide / charcoal composite, and then performing washing, drying and grinding to obtain the iron oxide / charcoal composite.

2. The method for preparing an iron oxide / soot composite according to claim 1, characterized in that, In step S1, the impregnation treatment is as follows: 10-30 g of wood chip samples are immersed in 100-400 mL of a Fe (NO3) 3·9H2O solution with a concentration of 0.1-1.0 mol / L, and then stirred at 40-80 ℃ and 200-400 rpm for 4-8 h.

3. The method for preparing an iron oxide / soot composite according to claim 1, characterized in that, In step S2, the first heat treatment is as follows: drying at 100-110 ℃ for 6-10 h.

4. The method for preparing an iron oxide / soot composite according to claim 1, characterized in that, In step S3, the second heat treatment is as follows: heating to 700-800 ℃ at a heating rate of 8-12 ℃ / min under inert gas protection, and keeping the temperature constant for 0.5-1.5 h.

5. The method for preparing the iron oxide / black carbon composite according to claim 1, characterized in that, In step S3, the washing treatment is as follows: washing with anhydrous ethanol and pure water respectively until neutral.

6. An iron oxide / charcoal composite for enhancing the degradation of antibiotics by anaerobic microorganisms, characterized in that, The iron oxide / charcoal composite is prepared by the method according to any one of claims 1-5.

7. Use of the iron oxide / soot composite according to claim 6 for the intensification of anaerobic microbial wastewater treatment, characterized in that, Anaerobic sludge is first added to the wastewater to be treated, and stirred uniformly to obtain a stable sludge system; Then the iron oxide / charcoal composite is mixed with the stable sludge system to obtain a material-sludge mixed system, and stirred uniformly to remove the antibiotics in the wastewater.

8. Use according to claim 7, characterized in that, The anaerobic sludge is active sludge that is pollution-free, contains anaerobic bacteria, and can quickly start the anaerobic digestion reaction of sludge; The total suspended solids concentration in the stable sludge system is 10-40 g / L, and the volatile suspended solids concentration is 5-20 g / L; The addition amount of the iron oxide / charcoal composite in the mixed system is 1.5-2.5 g / L.

9. Use according to claim 7, characterized in that, The material-sludge mixed system is shaken at 25-35 ℃ and 100-200 rpm to fully contact and remove the antibiotics.

10. Use according to claim 7, characterized in that, It is suitable for biological enhanced degradation of antibiotics in wastewater treatment, contaminated groundwater remediation and actual engineering systems; The antibiotics in the wastewater are sulfadimethoxine.

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