Method for relieving inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar

Abstract

The invention provides a method for relieving inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar, and belongs to the technical field of wastewater treatment. The method comprises the following steps: adding cow dung biochar into a to-be-treated system for carrying out anaerobic digestion on the quinolone antibiotic wastewater by adopting anaerobic sludge; wherein the cow dung biochar is obtained by pyrolyzing cow dung. According to the method, cow dung biochar is added into a to-be-treated system, the cow dung biochar has good adsorption and electrochemical performance and the like, the surface of the cow dung biochar contains a proper amount of iron, the inhibition effect of antibiotics on anaerobic digestion can be well relieved, and the methane yield and the antibiotic removal efficiency of the system can be improved; meanwhile, compared with a nano iron-carbon composite material, the cow dung biochar does not need a complex pretreatment process, and is convenient to operate.

Description

Technical Field

[0001] The present application relates to the technical field of wastewater treatment, and in particular to a method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar. Background Art

[0002] Antibiotics are currently widespread in water and soil environments, primarily from pharmaceutical and aquaculture wastewater. Quinolones, with their broad antimicrobial spectrum, strong antimicrobial activity, lack of cross-resistance with other antimicrobial drugs, and minimal toxic side effects, are widely used in livestock and aquaculture. Ciprofloxacin, in particular, can reach concentrations of 2 mg / L or higher in some aquaculture wastewater.

[0003] Currently, the main methods for removing quinolone antibiotics such as ciprofloxacin from wastewater include electrochemical membrane filtration, adsorption, advanced oxidation, and biological methods. Electrochemical membrane filtration removes pollutants from water through the synergistic effect of electrochemical reactions and membrane filtration, but it consumes a lot of energy and is expensive. Adsorption uses porous materials as adsorbents to adsorb antibiotics to achieve wastewater treatment, but there are problems with adsorbent saturation and regeneration. Advanced oxidation methods oxidize antibiotics into low-toxic or non-toxic small molecules by generating highly oxidizing free radicals. These methods include photochemical oxidation, catalytic wet oxidation, sonochemical oxidation, ozone oxidation, electrochemical oxidation, Fenton oxidation, etc., but require specialized equipment and specific chemicals. Biological methods use microorganisms to degrade antibiotics. Among them, anaerobic digestion is a highly efficient technology that can convert pollutants into clean energy. It has the advantages of low sludge volume and low energy consumption, and plays an important role in water treatment. However, the presence of antibiotics can seriously inhibit anaerobic digestion.

[0004] Biochar materials have good adsorption and electrochemical properties and can have a positive impact on anaerobic microbial populations. Using them in anaerobic digestion of aquaculture wastewater to alleviate the negative effects of antibiotics has unique advantages such as simple operation, no need for land occupation, and energy recovery.

[0005] Some studies have shown that adding nano-iron-carbon composites to antibiotic wastewater has effectively reduced the inhibitory effect of antibiotics on anaerobic digestion. However, this method typically requires the use of a liquid-phase reduction process to reduce iron salts to produce nano-zero-valent iron. This involves the use of sodium borohydride, a highly corrosive and explosive reducing agent, and requires an oxygen-free environment during the preparation process. Summary of the Invention

[0006] The purpose of the present application is to provide a method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar. The method adds cow dung biochar to the system to be treated. The cow dung biochar has good adsorption and electrochemical properties. Moreover, the surface of the cow dung biochar contains an appropriate amount of iron, which can effectively alleviate the inhibitory effect of antibiotics on anaerobic digestion, and is beneficial to improving the system's methane production and antibiotic removal efficiency. At the same time, compared with nano-iron-carbon composite materials, cow dung biochar does not require a complicated pretreatment process and is easy to operate.

[0007] The embodiment of the present application is implemented as follows:

[0008] The present invention provides a method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar, comprising:

[0009] Cow dung biochar is added to a treatment system for anaerobic digestion of quinolone antibiotic wastewater using anaerobic sludge; wherein the cow dung biochar is obtained by pyrolysis of cow dung.

[0010] The method provided in the embodiment of the present application for alleviating the inhibition of quinolone antibiotics on anaerobic digestion by using cow dung biochar, by adding cow dung biochar to the system to be treated, has at least the following beneficial effects:

[0011] 1. Converting cow dung into cow dung biochar through resource processing and applying the cow dung biochar to wastewater treatment can reduce pollution and create economic value, and can be used as an important way to utilize agricultural waste.

[0012] 2. Cow dung charcoal has a rough surface and a large specific surface area, which makes it easier to adsorb antibiotics, relieve antibiotic inhibition, and make it easier for microorganisms to colonize on it and enrich anaerobic microorganisms, which is conducive to the removal of antibiotics.

[0013] 3. Compared with conventional biochar, cow dung biochar has a -1 and 462cm -1 The peak intensity at is significantly enhanced, indicating that its CO, aromatic structure and metal oxide contents are higher, indicating that cow dung biochar has a stronger adsorption capacity for polar pollutants, superior adsorption effect for hydrophobic pollutants, better microbial attachment and electron transfer performance, which is beneficial to the removal of antibiotics.

[0014] 4. The surface of cow dung biochar contains an appropriate amount of iron (iron is mainly in the form of iron ions, which can act as an electron shuttle to promote direct interspecies electron transfer between microorganisms). Compared with conventional biochar, the iron element on the surface of cow dung biochar can provide a better environment for anaerobic digestion and promote methane production. Therefore, it can not only remove antibiotics, but also simultaneously realize the recycling and utilization of biogas, with the dual advantages of environmental and economic benefits; compared with nano-iron-carbon composite materials, it can avoid dissolution caused by excessive iron content, and avoid the dissolved iron elements from poisoning microorganisms, which is beneficial to the removal of antibiotics.

[0015] 5. Cow dung biochar is directly obtained by pyrolysis of cow dung. Compared with nano iron-carbon composite materials, it does not require complicated pretreatment processes and is easy to operate.

[0016] In some embodiments, the cow dung biochar is obtained by pyrolyzing cow dung at 500-700° C. in a nitrogen atmosphere for 2-3 hours.

[0017] In some embodiments, the cow dung biochar satisfies at least one of the following conditions (a1) to (a2);

[0018] (a1) Specific surface area is 40 to 100 m 2 / g;

[0019] (a2) The surface has a honeycomb structure with a multi-layer pore network.

[0020] In some embodiments, the cow dung biochar satisfies at least one of the following conditions (b1) to (b4);

[0021] (b1) pores are mainly mesopores;

[0022] (b2) average pore diameter of 5 to 20 nm;

[0023] (b3) Total pore volume is 0.065 to 0.080 cm 3 / g, and the BJH mesopore volume is 0.050~0.060cm 3 / g;

[0024] (b4) The type of adsorption isotherm is type IV.

[0025] In some embodiments, the cow dung biochar meets the following conditions: Fe 2+ and Fe 3+ The total content is 5 to 20 wt%;

[0026] Optional, Fe in cow dung biochar 3+ The content is higher than Fe 2+ content.

[0027] In some embodiments, the cow dung biochar satisfies the following conditions: the surface functional groups include OH, C=O, CO, Fe-O, and CH.

[0028] In some embodiments, in the quinolone antibiotic wastewater, the quinolone antibiotics include at least one of ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, moxifloxacin and lomefloxacin.

[0029] In some embodiments, the quinolone antibiotic wastewater is aquaculture wastewater;

[0030] Optionally, before anaerobic digestion, the concentration of quinolone antibiotics in the quinolone antibiotic wastewater is ND to 3 mg / L.

[0031] In some embodiments, the added weight of cow dung biochar is X1, and the volume of quinolone antibiotic wastewater is X2, wherein 5 g / L≤X1 / X2≤20 g / L;

[0032] Optional, 5g / L≤X1 / X2≤10g / L.

[0033] In some embodiments, anaerobic digestion satisfies at least one of the following conditions (c1) to (c3);

[0034] (c1) The pH value of the influent in the system to be treated is 6.5 to 8.5;

[0035] (c2) The pH value of anaerobic sludge is 6.8-7.5;

[0036] (c3) The temperature of anaerobic digestion is 36-38°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 The SEM images of the biochars in the examples and comparative examples of the present application are shown;

[0039] Figure 2 The XPS graphs of the biochars in the examples and comparative examples of the present application are shown;

[0040] Figure 3 This is the infrared Fourier image of the biochar in the examples and comparative examples of the present application. DETAILED DESCRIPTION

[0041] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0042] It should be noted that “and / or” in this application, such as “Feature 1 and / or Feature 2”, refers to three situations: “Feature 1” alone, “Feature 2” alone, or “Feature 1” plus “Feature 2”.

[0043] In addition, in the description of this application, unless otherwise specified, the meaning of "multiple" in "one or more" refers to two or more; the range of "value a to value b" includes the two end values "a" and "b", and the "unit of measurement" in "value a to value b+unit of measurement" represents the "unit of measurement" of both "value a" and "value b".

[0044] The technical solutions of the embodiments of the present application are exemplarily described below.

[0045] An embodiment of the present application provides a method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar, comprising: adding cow dung biochar to a system to be treated in which anaerobic digestion of quinolone antibiotic wastewater is performed using anaerobic sludge; wherein the cow dung biochar is obtained by pyrolysis of cow dung.

[0046] In this application, cow dung biochar is used to alleviate the inhibition of quinolone antibiotics on anaerobic digestion, which includes the following working mechanisms:

[0047] This biochar has a huge specific surface area, rich pore structure and multiple surface functional groups, which can produce a strong adsorption effect on quinolone antibiotics such as ciprofloxacin in anaerobic systems. Its adsorption mechanism of pollutants mainly includes surface complexation, pore filling, electrostatic interaction, hydrogen bonding and π-π bonding.

[0048] The abundance of functional groups (OH, C=O, CO, CH, etc.) on the surface of the biochar enhances its ability to provide electrons and improves the efficiency of direct interspecies electron transfer between microorganisms, thereby increasing the methane production of anaerobic digestion; some specific functional groups enhance its adsorption capacity for polar and hydrophobic pollutants (such as quinolone antibiotics such as ciprofloxacin).

[0049] The advantages of the biochar's specific surface area and pore structure make it easy for microorganisms to attach and grow on it, thereby enriching functional microorganisms related to methane production and antibiotic degradation, making this type of functional microorganism the dominant population. Its ability to adsorb antibiotics will also alleviate the inhibitory effects on microorganisms, enrich microbial diversity, enhance system stability and toxicity resistance, and help improve the system's methane production and antibiotic removal efficiency.

[0050] The biochar can also avoid the oxidative stress response of microorganisms and enhance the antioxidant capacity of bacteria. This antioxidant capacity usually means reduced damage to the microbial cell membrane, effectively improving the methane production performance of anaerobic digestion under antibiotic pressure.

[0051] Based on the above working mechanism, the method provided in the embodiment of the present application for alleviating the inhibition of quinolone antibiotics on anaerobic digestion by using cow dung biochar, by adding cow dung biochar to the system to be treated, has at least the following beneficial effects:

[0052] 1. Converting cow dung into cow dung biochar through resource processing and applying the cow dung biochar to wastewater treatment can reduce pollution and create economic value, and can be used as an important way to utilize agricultural waste.

[0053] 2. Cow dung charcoal has a rough surface and a large specific surface area, which makes it easier to adsorb antibiotics, relieve antibiotic inhibition, and make it easier for microorganisms to colonize on it and enrich anaerobic microorganisms, which is conducive to the removal of antibiotics.

[0054] Specifically, the study found that the pores of conventional biochar obtained by pyrolysis of wood are mainly micropores (pores with a diameter of less than 2nm are called micropores), which are only suitable for the adsorption of small molecules (such as gases); while the pores of cow dung biochar obtained by pyrolysis of cow dung are mainly mesopores (pores with a diameter of 2 to 50nm are called mesopores or mesopores), which makes it perform better in adsorbing large molecular pollutants (such as quinolone antibiotics).

[0055] In addition, the biochar obtained by wood pyrolysis is generally a microporous single-layer adsorption with a small hysteresis loop; while the cow dung biochar obtained by cow dung pyrolysis usually has a complex multi-layer pore network on the surface, showing a honeycomb structure, which is more conducive to the diffusion and distribution of antibiotics on it.

[0056] 3. Compared with conventional biochar (e.g. biochar obtained by pyrolysis of wood or sludge), cow dung biochar has a -1 and 462cm -1 The peak intensity at is significantly enhanced, indicating that its CO, aromatic structure and metal oxide contents are higher, indicating that cow dung biochar has a stronger adsorption capacity for polar pollutants, superior adsorption effect for hydrophobic pollutants, better microbial attachment and electron transfer performance, which is beneficial to the removal of antibiotics.

[0057] Specifically, the study found that cow dung biochar at 1045cm -1 and 462cm -1 The significantly enhanced peak intensity at is its unique property, which is due to the high cellulose content of cow dung and the pyrolysis generation of Fe oxides. Conventional biochar is difficult to reproduce this property.

[0058] 4. The surface of cow dung biochar contains an appropriate amount of iron (iron is mainly in the form of iron ions, which can act as an electron shuttle to promote direct interspecies electron transfer between microorganisms). Compared with conventional biochar, the iron element on the surface of cow dung biochar can provide a better environment for anaerobic digestion and promote methane production. Therefore, it can not only remove antibiotics, but also simultaneously realize the recycling and utilization of biogas, with the dual advantages of environmental and economic benefits; compared with nano-iron-carbon composite materials, it can avoid dissolution caused by excessive iron content, and avoid the dissolved iron elements from poisoning microorganisms, which is beneficial to the removal of antibiotics.

[0059] Specifically, the study found that conventional biochar typically has very low surface iron content. However, in iron-loaded biochar, excessive iron content can lead to iron leaching and toxicity to microorganisms. For example, biochar with a 66% iron loading can toxicize microorganisms due to iron leaching. However, the surface iron content of cow dung biochar is typically between 5% and 20% by weight. This optimal iron content effectively promotes anaerobic digestion while preventing leached iron from toxicating microorganisms.

[0060] The biodegradation rate of quinolone antibiotics (such as ciprofloxacin) by cow dung biochar is generally greater than 95%, while the degradation rate of nano-iron-carbon composite materials is generally 80-90%. It can be seen that compared with biochar with additional iron loading (such as nano-iron-carbon composite materials), cow dung biochar has a higher antibiotic removal effect.

[0061] 5. Cow dung biochar is directly obtained by pyrolysis of cow dung. Compared with nano iron-carbon composite materials, it does not require complicated pretreatment processes and is easy to operate.

[0062] It should be noted that, in the examples of the present application, unless otherwise specified, the types of quinolone antibiotics are not limited.

[0063] In some embodiments, in the quinolone antibiotic wastewater, the quinolone antibiotic includes at least one of ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, moxifloxacin and lomefloxacin; as an example, the quinolone antibiotic is ciprofloxacin.

[0064] The method provided in the examples of the present application can play a better role in aquaculture wastewater with a high concentration of quinolone antibiotics. Therefore, the method provided in the examples of the present application is exemplarily applied to the treatment of aquaculture wastewater containing quinolone antibiotics.

[0065] As an example, the quinolone antibiotic wastewater is aquaculture wastewater, such as aquaculture wastewater containing ciprofloxacin.

[0066] Optionally, before anaerobic digestion, the concentration of quinolone antibiotics in the quinolone antibiotic wastewater is ND~3 mg / L, further ND~2 mg / L, for example, but not limited to, any one of 0.5 mg / L, 1 mg / L, 1.5 mg / L, 2 mg / L, 2.5 mg / L, 3 mg / L or a range between any two of them.

[0067] Among them, ND stands for not detected.

[0068] In some embodiments, the cow dung biochar is obtained by pyrolyzing cow dung at 500-700° C. in a nitrogen atmosphere for 2-3 hours.

[0069] Among them, the pyrolysis temperature is, for example but not limited to, any one of 500°C, 550°C, 600°C, 650°C, 700°C, or a range between any two of them; the pyrolysis time is, for example but not limited to, any one of 2h, 2.5h, 3h, or a range between any two of them.

[0070] In the above technical solution, cow dung biochar is prepared by pyrolyzing cow dung under appropriate conditions, which is conducive to the cow dung biochar having the following physical and chemical properties: rough surface, large specific surface area, rich pore structure, appropriate iron content, and multiple surface functional groups.

[0071] It should be noted that in the embodiments of the present application, after the cow dung biochar is pyrolyzed by cow dung, it can be rinsed with clean water (such as deionized water) without the need for acid washing or other chemical reagent washing processes.

[0072] Based on the above-mentioned specific pyrolysis conditions, the physical and chemical properties of the obtained cow dung biochar are exemplified as follows.

[0073] In some embodiments, the cow dung biochar satisfies at least one of the following conditions (a1) to (a2): (a1) the specific surface area is 40 to 100 m 2 / g, further 40~50m 2 / g; (a2) The surface has a honeycomb structure with a multi-layer pore network.

[0074] Among them, cow dung biochar has a large specific surface area, a rough surface and a complex multi-layer pore network, which is conducive to the diffusion and distribution of antibiotics on it.

[0075] In some embodiments, the cow dung biochar satisfies at least one of the following conditions (b1) to (b4): (b1) the pores are mainly mesopores; (b2) the average pore size is 5 to 20 nm, further 5 to 10 nm; (b3) the total pore volume is 0.065 to 0.080 cm 3 / g, and the BJH mesopore volume is 0.050~0.060cm 3 / g; (b4) The type of adsorption isotherm is type IV.

[0076] The pores are mainly mesopores, which means that the BJH mesopore volume accounts for more than 50% of the total pore volume, such as more than 60%, or more than 70%, or even more than 80%.

[0077] The pores of cow dung biochar are mainly mesopores, which makes it perform better in adsorbing large molecular pollutants (such as quinolone antibiotics); the higher pore volume can provide more active sites.

[0078] In some embodiments, the cow dung biochar meets the following conditions: Fe 2+ and Fe 3+ The total content of Fe is 5 to 20 wt%; optionally, in the cow dung biochar, Fe 3+ The content is higher than Fe 2+ content.

[0079] Among them, iron is in the form of iron ions in moderate amounts, which can act as an electron shuttle to promote direct electron transfer between microorganisms; Fe 2+ It can be used as a food supply for microorganisms, and methanogens are sensitive to Fe 3+ Sensitive, beneficial for methane production and antibiotic removal.

[0080] In some embodiments, the cow dung biochar satisfies the following conditions: the surface functional groups include OH, C=O, CO, Fe-O, and CH.

[0081] Among them, OH is conducive to the adsorption of polar molecules, C=O can serve as a polar adsorption site, CO and Fe-O can promote electron transfer, and aromatic CH can promote π-π interaction to adsorb hydrophobic antibiotics.

[0082] In some embodiments, the added weight of cow dung biochar is X1, and the volume of quinolone antibiotic wastewater is X2, wherein 5 g / L≤X1 / X2≤20 g / L;

[0083] As an example, the value of X1 / X2 may be, but is not limited to, any one of 5g / L, 6g / L, 7g / L, 8g / L, 9g / L, 10g / L, 11g / L, 12g / L, 13g / L, 14g / L, 15g / L, 16g / L, 17g / L, 18g / L, 19g / L and 20g / L, or a range between any two of them.

[0084] Optional, 5g / L≤X1 / X2≤10g / L.

[0085] In the above technical solution, the cow dung biochar is added in an appropriate amount, which can effectively alleviate the inhibitory effect of antibiotics on anaerobic digestion and effectively increase methane production and antibiotic removal rate. For example, when applied to wastewater treatment with high concentrations of quinolone antibiotics, it can also achieve good results. In some embodiments, anaerobic digestion meets at least one of the following conditions (c1) to (c3);

[0086] (c1) The pH value of the influent in the system to be treated is 6.5 to 8.5, preferably 7.0 ± 0.1;

[0087] (c2) the pH value of the anaerobic sludge is 6.8 to 7.5, further 7.0 to 7.3;

[0088] (c3) The temperature of anaerobic digestion is 36℃~38℃.

[0089] In the above technical solution, controlling the pH value and temperature at appropriate conditions is beneficial to the anaerobic digestion reaction and the growth of methanogens, thereby increasing the methane production and improving the antibiotic removal rate.

[0090] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0091] 1. The experimental conditions of each embodiment and comparative example are as follows:

[0092] Biochar preparation: Abandoned fruit wood (apple wood, taken from agricultural production waste), dehydrated sludge (collected from urban sewage treatment plants), and dry cow dung (taken from agricultural production waste) were collected as biochar raw materials. They were pyrolyzed at 600°C in a nitrogen atmosphere for 3 hours to obtain three types of biochar: wood biochar, sludge biochar, and cow dung biochar. The obtained biochar was passed through a 100-mesh sieve to control the particle size between 100 and 200 meshes, washed with deionized water, and dried in an oven at 105°C. After drying, it was sealed and stored.

[0093] Preparation of anaerobic sludge: taken from sewage treatment plant, acclimated in laboratory, pH value is 7.0-7.3.

[0094] Synthetic simulated aquaculture wastewater: glucose 5.625 g / L, ammonium chloride 0.4 g / L, potassium dihydrogen phosphate 0.165 g / L, ciprofloxacin 1-3 mg / L, COD concentration of 6000 mg / L, COD:N:P=300:5:2, and pH was adjusted to 7.0±0.1 using hydrochloric acid.

[0095] A 1L serum bottle with two holes in the cap was used as the reactor to collect gas, supernatant, and sludge. In both experimental groups, 600mL of simulated aquaculture wastewater was added as substrate and 200mL of anaerobic sludge was added as inoculum.

[0096] Three replicates were prepared for each experimental group. A specific amount and type of biochar was added to mitigate the inhibition of ciprofloxacin. The reactors were incubated in a constant-temperature shaking incubator (37°C, 150 rpm). Methane content was collected and measured daily, and the supernatant was regularly collected to measure anaerobic physical and chemical parameters. The reaction was considered complete when the reactor ceased gas production.

[0097] The conditions for adding biochar in the examples and comparative examples are shown in Table 1.

[0098] Table 1. Biochar addition conditions

[0099] serial number name Antibiotic concentration Types of biochar Biochar addition amount Example 1 Cowdung 2mg / L Cow dung biochar 5g / L Example 2 Cowdung 2mg / L Cow dung biochar 7g / L Example 3 Cowdung 2mg / L Cow dung biochar 9g / L Example 4 Cowdung 1mg / L Cow dung biochar 5g / L Example 5 Cowdung 3mg / L Cow dung biochar 5g / L Comparative Example 1 Sludge 2mg / L Sludge biochar 5g / L Comparative Example 2 Wood 2mg / L Wood biochar 5g / L Comparative Example 3 Control 2mg / L / /

[0100] 2. The test results of each embodiment and comparative example experiment are as follows:

[0101] 1. The specific surface area and porosity of biochar were determined using a fully automatic physical adsorption instrument (Micromeritics ASAP 2460, USA); the surface microporous structure of biochar was determined using a scanning electron microscope (Thermo Scientific Apreo 2C, USA).

[0102] Figure 1 SEM images of biochar, where (a) and (d) are wood biochar, (b) and (e) are sludge biochar, and (c) and (f) are cow dung biochar.

[0103] The specific surface area and pore structure of biochar are shown in Table 2.

[0104] Table 2. Specific surface area and pore structure of biochar

[0105]

[0106] according to Figure 1 From Table 2, we can see that:

[0107] Wood biochar is dominated by micropores, has an extremely high micropore ratio, and very few mesopores, which is only suitable for the adsorption of small molecules (such as gases); the adsorption isotherm type is Type I, micropore monolayer adsorption, and a small hysteresis loop; the surface roughness is low, the micropores are dense but the structure is regular.

[0108] Macropores dominate in sludge biochar, with a mixture of macropores and mesopores and almost no micropores. The adsorption isotherm type is a II / IV mixed type, showing a smooth curve and multi-layer adsorption. The surface roughness is higher than that of wood biochar but lower than that of cow dung biochar. It is mainly macropores and has a small specific surface area.

[0109] Cow dung biochar is dominated by mesopores and is rich in mesopores, which makes it perform better in adsorbing large molecular pollutants (such as quinolone antibiotics); compared with sludge biochar, cow dung biochar has a higher pore volume and specific surface area, which can increase more active sites; the adsorption isotherm type is type IV, with obvious hysteresis loops and mesoporous capillary condensation; the mesopores are widely distributed, the pore size complexity is high, the surface roughness is high, and the surface has a complex multi-layer pore network, which appears as a honeycomb structure, which is conducive to the diffusion and distribution of antibiotics on it.

[0110] 2. The elemental composition of biochar was determined by scanning electron microscopy (Thermo Scientific Apreo 2C, USA); the chemical state and distribution characteristics of Fe element in biochar were detected by X-ray photoelectron spectroscopy (XPS).

[0111] The elemental composition of cow dung biochar is shown in Table 3.

[0112] Table 3. Elemental composition of cow dung biochar

[0113] element Wt% At% C 26.32 36.86 N 1.26 1.52 O 53.04 55.78 Fe 19.38 5.84 sum 100 100

[0114] According to Table 3, we can see that:

[0115] Cow dung biochar has a suitable iron content.

[0116] Figure 2 This is the XPS graph of biochar, where from left to right are wood biochar, sludge biochar and cow dung biochar.

[0117] according to Figure 2 It can be seen that the Fe2p spectrum of wood biochar does not show obvious characteristic peaks, indicating that the content of Fe in wood biochar is extremely low or in an amorphous form. In contrast, the Fe2p spectra of sludge biochar and cow dung biochar clearly show that Fe 2+ and Fe 3+ The characteristic peak of Fe 2+ (710.23eV 19.45%, 709.71eV 20.81%) corresponding to Fe2p1 / 2, Fe2+ (724.56eV 19.39%, 714.98eV 33.61%) corresponds to Fe2p3 / 2 in sludge biochar and cow dung biochar. 3+ (712.27eV 23.40%, 711.91eV 23.25%) corresponds to Fe2p1 / 2, Fe 3+ (728.78eV 11.29%, 723.13eV 2.64%) corresponds to Fe2p3 / 2 in sludge biochar and cow dung biochar. 2+ The proportion of Fe in cow dung biochar is relatively high. 3+ In addition, satellite peaks at 725eV and 730eV were observed in the Fe2p spectra of sludge biochar and cow dung biochar. These satellite peaks are Fe 3+ The typical characteristics of Fe 3+ The presence of Fe in these materials. 2+ / Fe 3+ Significantly higher than other biochars, among which Fe 2+ It can serve as a food supply for microorganisms and promote anaerobic digestion, while methanogens are sensitive to Fe 3+ It is sensitive and can be seen that cow dung biochar is more conducive to improving the system methane production and antibiotic removal efficiency.

[0118] 3. The surface functional groups of biochar materials were determined using an infrared spectrometer (Thermo Fisher NicoletIs5, USA).

[0119] Figure 3 This is the infrared Fourier map of biochar.

[0120] according to Figure 3 It can be seen that:

[0121] Compared with the other two biochars, cow dung biochar has a -1 and 462cm -1 The peak intensity at is significantly enhanced, indicating that its CO, aromatic structure and metal oxide contents are higher, indicating that cow dung biochar has a stronger adsorption capacity for polar pollutants, superior adsorption effect for hydrophobic pollutants, better microbial attachment and electron transfer performance, which is beneficial to the removal of antibiotics.

[0122] 4. Use gas chromatography (GC2088 TCD) to detect gas composition and content; use high performance liquid chromatography to determine the concentration of ciprofloxacin.

[0123] The cumulative methane production and ciprofloxacin removal efficiency are shown in Table 4 below.

[0124] Table 4. Cumulative methane production and ciprofloxacin removal efficiency

[0125]

[0126]

[0127] According to Table 4, we can see that:

[0128] The experimental group with added cow dung biochar was able to better alleviate the inhibition of antibiotics on anaerobic digestion, and had higher methane production and antibiotic removal rate.

[0129] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar, characterized in that: include: Cow dung biochar is added to a system for anaerobic digestion of quinolone antibiotic wastewater using anaerobic sludge; wherein the cow dung biochar is obtained by pyrolysis of cow dung.

2. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to claim 1, characterized in that: The cow dung biochar is obtained by pyrolyzing the cow dung in a nitrogen atmosphere at 500-700° C. for 2-3 hours.

3. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to claim 2, characterized in that: The cow dung biochar satisfies at least one of the following conditions (a1) to (a2); (a1) Specific surface area is 40 to 100 m 2 / g; (a2) The surface has a honeycomb structure with a multi-layer pore network.

4. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to claim 2, characterized in that: The cow dung biochar satisfies at least one of the following conditions (b1) to (b4); (b1) pores are mainly mesopores; (b2) average pore diameter of 5 to 20 nm; (b3) Total pore volume is 0.065 to 0.080 cm 3 / g, and the BJH mesopore volume is 0.050~0.060cm 3 / g; (b4) The type of adsorption isotherm is type IV.

5. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to claim 2, characterized in that: The cow dung biochar meets the following conditions: surface EDS detection of Fe 2+ and Fe 3+ The total content is 5 to 20 wt%; Optionally, in the cow dung biochar, the Fe 3+ The content is higher than the Fe 2+ content.

6. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to claim 2, characterized in that: The cow dung biochar meets the following conditions: the surface functional groups include OH, C=O, CO, Fe-O and CH.

7. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to any one of claims 1 to 6, characterized in that: In the quinolone antibiotic wastewater, the quinolone antibiotics include at least one of ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, moxifloxacin and lomefloxacin.

8. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to claim 7, characterized in that: The quinolone antibiotic wastewater is aquaculture wastewater; Optionally, before the anaerobic digestion is performed, the concentration of the quinolone antibiotics in the quinolone antibiotic wastewater is ND to 3 mg / L.

9. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to any one of claims 1 to 6, characterized in that: The added weight of the cow dung biochar is X1, and the volume of the quinolone antibiotic wastewater is X2, wherein 5g / L≤X1 / X2≤20g / L; Optional, 5g / L≤X1 / X2≤10g / L.

10. The method for alleviating the inhibition of quinolone antibiotics on anaerobic digestion based on cow dung biochar according to any one of claims 1 to 6, characterized in that: The anaerobic digestion satisfies at least one of the following conditions (c1) to (c3); (c1) the pH value of the influent in the system to be treated is 6.5 to 8.5; (c2) the pH value of the anaerobic sludge is 6.8 to 7.5; (c3) The temperature of the anaerobic digestion is 36°C to 38°C.

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