Electroactive microbial system and method for removing parachlorophenol

Abstract

The invention relates to an electroactive microbial system for removing parachlorophenol and a method thereof, and aims to provide an electroactive microbial strain for reducing Fe < 0 > oxidized under the condition of oxygen, generating active Fe < 2 + > and further removing parachlorophenol, so that the defect that Fe < 0 > is easy to passivate when organic pollutants are treated is overcome. In addition, an allogenic material is also introduced, so that the degradation efficiency of the electroactive microorganism enhanced zero-valent iron aeration system on 4-CP is improved; the operation is simple, the cost is low, and meanwhile, the pollution to the environment is avoided; according to the technical scheme, the electroactive microbial system for removing parachlorophenol comprises the following components: 0.08 g / L to 0.60 g / L of zero-valent iron, 0.5 mmol / L to 5.0 mmol / L of allogenic substances and 5 g / L to 40 g / L of electroactive microbial strains, the electroactive microbial strains are shewanella decolorata S12 and shewanella putrefaciens SP200, and the electroactive microbial strains are prepared from the shewanella decolorata S12; the microbial inoculum is at least one of shewanella sp. MR-1 and sulfur reduction geobacter PCA; belongs to the field of environmental microorganisms.

Description

Technical Field

[0001] The invention belongs to the field of environmental microorganisms, and particularly relates to an electroactive microbial system for removing p-chlorophenol and a method thereof. Background Art

[0002] Phenolic wastewater is a typical industrial wastewater with high toxicity and poor biodegradability. Among all phenolic compounds, chlorophenol is considered a representative bio-persistent component and is widely used in chemicals such as dyes, herbicides, pesticides, pharmaceuticals, lubricant additives, and wood preservatives. Parachlorophenol (4-CP), a typical chlorophenol pollutant, is highly toxic and has persistent bioaccumulation. Common treatment methods currently include adsorption, oxidation, biological methods, and enzymatic degradation.

[0003] Iron and its oxides are widely present in nature and have a lasting impact on the environment through the iron cycle. Due to the abundance and environmental friendliness of iron, the redox reaction of iron is very attractive for environmental remediation. 0 ) as the catalyst for the oxygen reduction reaction (ORR) to generate hydrogen peroxide, O2 - Since its first report in 2003, it has been used to remove arsenic (III), pesticides and aromatic pollutants. 0 / The aeration reaction system does not require the addition of oxidants (such as hydrogen peroxide or O3), which saves the cost of reagents and avoids potential safety hazards caused by the transportation and storage of oxidants. From an economic and environmental perspective, Fe 0 Aeration processes are ideal for pollutant control and environmental remediation. However, the application of nZVI still faces limitations, particularly its sensitivity to surface passivation, which leads to rapid deterioration of reactivity. Therefore, it is crucial to explore an environmentally friendly, economically viable, and effective solution to the challenge of surface oxidation.

[0004] In recent years, many types of microorganisms have been shown to be capable of biodegrading organic pollutants, including microbial communities, pure bacteria, and fungi. Among them, electroactive microorganisms are a class of microorganisms that can use organic matter as electron donors to reduce ferric oxide to ferrous iron. By combining electroactive microorganisms with iron-based materials, a system of electroactive microorganisms and iron-based materials can be formed, achieving efficient degradation of organic pollutants. Furthermore, electroactive microorganisms have strong bioadaptability and tolerance, allowing them to grow and reproduce in diverse environmental conditions, providing a broader application space for organic pollutant degradation. The facultative anaerobic bacterium Shewanella MR-1, a representative strain of EAB, is widely distributed in freshwater and marine environments and has been shown to accelerate the degradation of organic pollutants, including aromatic compounds, chlorinated pollutants, heavy metals, and radionuclides. Shewanella MR-1 typically oxidizes electron donors, such as lactate, to generate electrons, which are then transferred to terminal reductases within the cell or to extracellular substances to catalyze the conversion of pollutants. Although several strategies have been proposed to enhance metabolic capacity, such as modifying oxygen levels, temperature, and pH, degradation efficiency remains low. Therefore, some researchers have used multifunctional materials such as magnetite, zero-valent iron nanoparticles, and gold nanoparticles to improve degradation efficiency by reducing charge transfer resistance.

[0005] Therefore, an efficient, economical and environmentally friendly technical method is needed to remove parachlorophenol.

[0006] The present invention provides an electroactive microorganism to enhance Fe 0 / The method of removing organic pollutants by aeration system is simple to operate, low-cost, and will not pollute the environment. Summary of the Invention

[0007] In order to overcome the deficiencies in the prior art, the first object of the present invention is to provide an electroactive microbial system for removing para-chlorophenol, which utilizes electroactive microbial strains to reduce Fe 0 , producing active Fe 2+ , further remove parachlorophenol, solve the Fe 0 The present invention also introduces exogenous substances to enhance the degradation efficiency of 4-CP by the zero-valent iron aeration system enhanced by electroactive microorganisms.

[0008] The second object of the present invention is to provide a method for removing parachlorophenol; combining the synergistic effect of zero-valent iron and electroactive microbial strains in the non-cultivation process, the method is efficient in removing organic pollutants in water, is simple to operate, low in cost, and does not pollute the environment.

[0009] To this end, the first technical solution provided by the present invention is as follows:

[0010] An electroactive microbial system for removing para-chlorophenol comprises the following components: 0.08 g / L-0.60 g / L of zero-valent iron, 0.5-5.0 mmol / L of exogenous substances, and 5-40 g / L of electroactive microbial strains.

[0011] The electroactive microbial strain is at least one of Shewanella decolorizing S12, Shewanella putrefaciens SP200, Shewanella MR-1, and Geobacter sulfurreducens PCA.

[0012] Furthermore, in the electroactive microbial system for removing para-chlorophenol, the exogenous substance is one of ethylenediaminetetraacetic acid, riboflavin, humic acid, lactic acid, cytochrome c, and acetic acid.

[0013] Furthermore, in the electroactive microbial system for removing p-chlorophenol, the electroactive microbial strain is dissimilatory iron-reducing bacteria MR-1.

[0014] Furthermore, in the electroactive microbial system for removing para-chlorophenol, the electroactive microbial species are a combination of Shewanella MR-1 and Geobacter sulfurreducens PCA; the mass ratio of Shewanella MR-1 to Geobacter sulfurreducens PCA is 1-5:1.

[0015] Furthermore, in the electroactive microbial system for removing p-chlorophenol, the mass ratio of the Shewanella MR-1 and the Geobacter sulfurreducens PCA is 2:1.

[0016] Furthermore, in the electroactive microbial system for removing para-chlorophenol, the source substance is ethylenediaminetetraacetic acid.

[0017] The second technical solution provided by the present invention is as follows:

[0018] A method for removing p-chlorophenol adopts the electroactive microbial system for removing p-chlorophenol described in the first technical solution to perform removal under oxygen exposure.

[0019] Furthermore, the above-mentioned method for removing para-chlorophenol using an electroactive microbial enhanced aeration system comprises the following steps in sequence:

[0020] 1) resuscitating and culturing the electroactive microbial strains to prepare an electroactive microbial suspension;

[0021] 2) The exogenous substance zero-valent iron in the electroactive microbial suspension prepared in step 1) was added to the solution containing p-chlorophenol, and after uniform mixing, an aeration needle and a rubber stopper were inserted, and oxygen was exposed for 1 hour.

[0022] Furthermore, in the above-mentioned method for removing para-chlorophenol using the electroactive microbial enhanced aeration system, the concentration of para-chlorophenol is 5.0 mg / L;

[0023] The system has a zero-valent iron concentration of 0.08 g / L-0.60 g / L, an exogenous substance concentration of 0.5-5.0 mmol / L, and an electroactive microbial strain concentration of 5-40 g / L; and an oxygen exposure rate of 1-8 L / min.

[0024] The system consists of an electroactive microbial suspension, exogenous substances, zero-valent iron and a solution containing p-chlorophenol.

[0025] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0026] 1. The characteristics of the present invention are that zero-valent iron has a large specific surface area and strong reactivity to effectively remove organic pollutants. At the same time, by adding fresh bacterial liquid of electroactive microorganisms in a non-cultivation process, it solves the defect of easy passivation when treating organic pollutants.

[0027] 2. The zero-valent iron provided by the present invention can convert organic pollutants into easily degradable substances through reduction, oxygen can increase the metabolic activity and degradation efficiency of microorganisms, and microorganisms can convert pollutants into harmless substances or recycle them through their own biological actions.

[0028] 3. The present invention also introduces an exogenous substance EDTA to enhance the degradation efficiency of 4-CP by the zero-valent iron aeration system enhanced by electroactive microorganisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Effects of different exogenous substances on the removal of parachlorophenol

[0030] Figure 2 The degradation efficiency of EDTA in different systems for chlorophenol

[0031] Figure 3 is the degradation efficiency of p-chlorophenol under different concentrations of zero-valent iron;

[0032] Figure 4 is the degradation efficiency of p-chlorophenol under different concentrations of EDTA;

[0033] Figure 5 is the degradation efficiency of p-chlorophenol under different concentrations of MR-1;

[0034] Figure 6 The degradation efficiency of p-chlorophenol by exogenous substance EDTA in zero-valent iron aeration system enhanced by different bacterial strains;

[0035] Figure 7 Degradation efficiency of chlorophenol in mixed bacterial solution at different ratios;

[0036] Figure 8Degradation efficiency of p-chlorophenol under different concentrations of zero-valent iron;

[0037] Figure 9 Degradation efficiency of p-chlorophenol at different EDTA concentrations. DETAILED DESCRIPTION

[0038] The technical solutions of the present invention will be described clearly and completely below in conjunction with specific embodiments. The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The reagents in this embodiment are all commercially available products. It should be noted that, unless otherwise conflicting,

[0039] The strains used in the present invention and their sources are shown in Table 1 below:

[0040] Table 1

[0041]

[0042] Example 1 A method for preparing a suspension of electroactive microorganism Shewanella MR-1 comprises the following steps in sequence:

[0043] 1) Activate the MR-1 strain frozen at -80°C using LB agar medium (Guangdong Huankai Microbiology Technology Co., Ltd., Catalog No. 028330). Quickly remove the MR-1 cryovial from the -80°C freezer and briefly thaw at room temperature (approximately 1-2 minutes). Using a sterile inoculating loop, scoop a small amount of bacterial suspension near an alcohol burner on a clean bench and streak onto a preheated LB agar plate to obtain a single colony. Invert the plate and incubate in a 30°C incubator for 24 hours.

[0044] 2) Pick a single colony from the plate medium and place it in LB broth (Guangdong Huankai Microbiology Technology Co., Ltd., product number 028320), place it in a shaker at 30°C and 150 rpm for 36 hours to obtain a large number of bacteria. Pour the cultured MR-1 bacteria into a 50 ml sterile centrifuge tube and centrifuge (temperature 4°C, speed 6000 rpm). -1 The precipitate was washed twice with 0.9 wt % sterile saline and then washed once with ultrapure water.

[0045] 3) Transfer the centrifuged MR-1 pellet to a pre-weighed sterile centrifuge tube and accurately weigh the total mass using an analytical balance. Calculate the net mass of the pellet by subtracting the tare weight of the empty centrifuge tube. Add ultrapure water to a 1000 g / L (dry weight) MR-1 suspension. Store the suspension in a 4°C refrigerator for short-term storage (within 3 days) or use immediately in subsequent experiments.

[0046] Example 2

[0047] This embodiment provides a method for degrading p-chlorophenol using an electroactive microbial-enhanced zero-valent iron aeration system, comprising the following steps in sequence:

[0048] 1) Weigh 50 mg of p-chlorophenol (4-CP) into a 50 mL brown volumetric flask to prepare a 1 g / L p-chlorophenol stock solution. Store at -4°C. Then, take 2.5 mL of the stock solution and dilute to 500 mL with ultrapure water to obtain a 5.0 mg / L stock solution.

[0049] 2) 50 mL of a 5 mg / L p-chlorophenol solution was placed in a 100 mL serum bottle. 0.03 g of zero-valent iron and 0.25 mmol of the exogenous substance ethylenediaminetetraacetic acid were then added, so that the final concentrations of the zero-valent iron and the exogenous substance in the system (i.e., the total solution after preparation) were 0.60 g / L and 5.0 mmol / L, respectively.

[0050] 3) Add 2 mL of 1000 g / L MR-1 bacterial suspension to the mixture in step 2) to a concentration of 40 g / L. Stir the mixture on a magnetic stirrer at 400 rpm for 30 s to mix the solution evenly. Insert an aeration needle and rubber stopper and aerate with oxygen for 1 h at a flow rate of 4 L / min.

[0051] 4) 1 mL of sample was taken at 0, 5, 10, 15, 20, 30, 40, 50, and 60 min, and 1 mL of methanol was added to stop the reaction. After mixing the solution, the supernatant was centrifuged and filtered through a 0.22 μm organic filter membrane into a liquid phase bottle. The concentration of 4-CP in the solution was determined by high performance liquid chromatography.

[0052] The specific chromatographic conditions were systematically optimized as follows: the flow rate was set at 0.6 mL / min; methanol-water mixture system (V / V = 7:3); the excitation wavelength was 280 nm; the column temperature was controlled at 35 ± 0.5 °C; the automatic sampler injection volume was 10 μL; and the measurement time was 12 min.

[0053] Examples 3-7

[0054] The technical solutions provided in Examples 3-7 are basically the same as those in Example 2, with the only difference being the types of exogenous substances used. For details, see Table 1.

[0055] Table 1

[0056] Example exogenous substances Amount of exogenous substance added (mmol) Example 3 Acetic acid 0.25 Example 4 lactic acid 0.25 Example 5 Humic acid 0.25 Example 6 Riboflavin 0.25 Example 7 Cytochrome c 0.25 Blank group / 0

[0057] The degradation efficiency results of chlorophenol provided by the methods of Examples 2-7 are as follows: Figure 1As shown in the figure, it can be seen that EDTA, riboflavin, humic acid, lactic acid, cytochrome c, and acetic acid as exogenous substances can effectively promote the degradation of 4-CP. The promotion order is EDTA > riboflavin > humic acid > lactic acid > cytochrome c > acetic acid. Therefore, EDTA was subsequently selected as the exogenous substance of the present invention.

[0058] Example 8

[0059] This embodiment provides Fe 0 Method for the degradation of 4-CP using the +MR-1+O2+EDTA system: Weigh 50 mg of p-chlorophenol into a 50 mL brown volumetric flask to prepare a 1 g / L p-chlorophenol stock solution, which is then stored at -4°C. Then, take 2.5 mL of the stock solution and dilute it to 5.0 mg / L in a 500 mL volumetric flask with ultrapure water. Place 50 mL of this 5 mg / L p-chlorophenol solution into a 100 mL serum bottle, then add 0.03 g of zero-valent iron and 0.25 mmol of EDTA to a final concentration of 0.60 g / L zero-valent iron and 5.0 mmol / L in the system (i.e., the total solution after preparation). 2 mL of a 1000 g / L MR-1 bacterial suspension was added to the system, resulting in a concentration of 40 g / L. The solution was stirred at 400 rpm for 30 seconds to allow for homogenization. An aeration needle and rubber stopper were then inserted and oxygen was applied for 1 hour at a flow rate of 0-8 L / min. 1 mL samples were taken at 0, 5, 10, 15, 20, 30, 40, 50, and 60 minutes, and the reaction was stopped by adding 1 mL of methanol. After mixing, the supernatant was centrifuged and filtered through a 0.22 μm organic filter into a liquid chromatography flask. The 4-CP concentration in the solution was determined by high-performance liquid chromatography. The optimized chromatographic conditions were as follows: a flow rate of 0.6 mL / min; a methanol-water mixture (V / V = 7:3); an excitation wavelength of 280 nm; a column temperature of 35 ± 0.5°C; an autosampler injection volume of 10 μL; and a sampling time of 12 minutes.

[0060] Comparative Example 1 Degradation of 4-CP by EDTA-enhanced aeration system (O2+EDTA)

[0061] The method used in this comparative example is basically the same as that in Example 8, the only difference being that Shewanella MR-1 and Fe 0 Comparative Example 2 Degradation of 4-CP by EDTA and Shewanella MR-1 Enhanced Aeration System (EDTA+MR-1+O2) The method used in this comparative example is basically the same as that in Example 8, with the only difference being that Fe is not added. 0 .

[0062] Comparative Example 3 Degradation of 4-CP by EDTA and Shewanella MR-1 Enhanced System (EDTA+MR-1)

[0063] The method used in this comparative example is basically the same as that in Example 8. The only difference is that there is no O2 exposure and no Fe 0 .

[0064] Comparative Example 4 EDTA and Shewanella MR-1 Strengthening Zero-Valent Iron System (Fe 0 Degradation of 4-CP by MR-1+EDTA) The method used in this comparative example is basically the same as that in Example 8, the only difference being that there is no O2 exposure.

[0065] The degradation effects of the technical solutions provided in Example 8 and Comparative Examples 1-4 on 4-CP are as follows: Figure 2 As shown in the comparison 1-4 provided "O2+EDTA" "MR-1+EDTA" "Fe 0 +MR-1+EDTA" and "MR-1+O2+EDTA" systems, the 4-CP degradation rates were 1.41%, 5.43%, 50.58% and 17.05%, respectively. 0 Under the condition of the presence of certain active species can be generated to attack 4-CP. 0 +MR-1+O2+EDTA" system can degrade 4-CP by 89.16%, indicating that EDTA can partially dissolve Fe through complexation. 0 The passivation layer on the surface exposes fresh active sites and acts as an electron mediator to promote Fe 0 Electron transfer to O2.

[0066] Example 9

[0067] This embodiment provides a method for degrading p-chlorophenol using an electroactive microbial-enhanced zero-valent iron aeration system, comprising the following steps in sequence:

[0068] 1) Weigh 50 mg of p-chlorophenol into a 50 mL brown volumetric flask to prepare a 1 g / L p-chlorophenol stock solution, which is stored at -4°C. Then, take 2.5 mL of the stock solution and dilute to 500 mL with ultrapure water to obtain a 5.0 mg / L solution.

[0069] 2) 50 mL of a 5.0 mg / L p-chlorophenol solution was placed in a 100 mL serum bottle, and 0.004 g of zero-valent iron was added to achieve a final concentration of 0.08 g / L zero-valent iron in the system (i.e., the total solution after preparation).

[0070] 3) Add 0.25 mmol of EDTA to make the final EDTA concentration in the system (the system is the total solution after preparation) 5.0 mmol / L.

[0071] 4) Add 2 mL of 1000 g / L MR-1 bacterial suspension to a concentration of 40 g / L. Stir the mixture on a magnetic stirrer at 400 rpm for 30 seconds to mix the solution evenly. Insert an aeration needle and rubber stopper and expose to oxygen for 1 hour.

[0072] 5) 1 mL of sample was taken at 0, 5, 10, 15, 20, 30, 40, 50, and 60 min, and 1 mL of methanol was added to stop the reaction. After mixing the solution, the supernatant was centrifuged and filtered through a 0.22 μm organic filter membrane into a liquid phase bottle. The concentration of 4-CP in the solution was determined by high performance liquid chromatography.

[0073] The specific chromatographic conditions were systematically optimized as follows: the flow rate was set at 0.6 mL / min; methanol-water mixture system (V / V = 7:3); the excitation wavelength was 280 nm; the column temperature was controlled at 35 ± 0.5 °C; the automatic sampler injection volume was 10 μL; and the measurement time was 12 min.

[0074] Examples 10-13

[0075] The technical solutions provided in Examples 10-13 are basically the same as those in Example 9, with the only difference being the added mass of zero-valent iron and its final concentration. See Table 1 for details.

[0076] Table 3

[0077] Example Added mass of zero-valent iron (g) Final concentration of zero-valent iron (g / L) Example 10 0.005 0.10 Example 11 0.01 0.20 Example 12 0.02 0.40 Example 13 0.03 0.60

[0078] The degradation efficiency results of chlorophenol provided by the methods of Examples 9-13 are as follows: Figure 3 As shown in the figure, as the dosage of zero-valent iron increases from 0.08 g / L to 0.60 g / L, the degradation efficiency of p-chlorophenol shows an upward trend.

[0079] Example 14

[0080] This embodiment provides a method for degrading p-chlorophenol using an electroactive microbial-enhanced zero-valent iron aeration system, comprising the following steps in sequence:

[0081] 1) Weigh 50 mg of p-chlorophenol into a 50 mL brown volumetric flask to prepare a 1 g / L p-chlorophenol stock solution, which is stored at -4°C. Then, take 2.5 mL of the stock solution and dilute to 500 mL with ultrapure water to obtain a 5.0 mg / L solution.

[0082] 2) 50 mL of a 5 mg / L p-chlorophenol solution was placed in a 100 mL serum bottle, and 0.03 g of zero-valent iron was added to achieve a final concentration of 0.60 g / L in the system (i.e., the total solution after preparation).

[0083] 3) Add 0.025 mmol of EDTA to make the final EDTA concentration in the system (the system is the total solution after preparation) 0.5 mmol / L.

[0084] 4) Add 2 mL of 1000 g / L MR-1 bacterial suspension to a concentration of 40 g / L. Stir the mixture on a magnetic stirrer at 400 rpm for 30 seconds to mix the solution evenly. Insert an aeration needle and rubber stopper and expose to oxygen for 1 hour.

[0085] 5) 1 mL of sample was taken at 0, 5, 10, 15, 20, 30, 40, 50, and 60 min, and 1 mL of methanol was added to stop the reaction. After mixing the solution, the supernatant was centrifuged and filtered through a 0.22 μm organic filter membrane into a liquid phase bottle. The concentration of 4-CP in the solution was determined by high performance liquid chromatography.

[0086] The specific chromatographic conditions were systematically optimized as follows: the flow rate was set at 0.6 mL / min; methanol-water mixture system (V / V = 7:3); the excitation wavelength was 280 nm; the column temperature was controlled at 35 ± 0.5 °C; the automatic sampler injection volume was 10 μL; and the measurement time was 12 min.

[0087] Examples 15-18

[0088] The technical solutions provided in Examples 15-18 are basically the same as the technical solution provided in Example 14, with the only difference being the added molar amount of EDTA and its final concentration. See Table 4 for details.

[0089] Table 4

[0090] Example Molar amount of EDTA added (mmol) Final EDTA concentration (mmol / L) Example 15 0.05 1.0 Example 16 0.075 1.5 Example 17 0.1 2.0 Example 18 0.25 5.0

[0091] The degradation efficiency results of the technical solutions provided in Examples 14-18 for chlorophenol are as follows: Figure 4 As shown in the figure, as the dosage of EDTA increased from 0.5 mmol / L to 5.0 mmol / L, the degradation efficiency of p-chlorophenol showed an upward trend.

[0092] Example 19

[0093] This embodiment provides a method for degrading p-chlorophenol using an electroactive microbial-enhanced zero-valent iron aeration system, comprising the following steps in sequence:

[0094] 1) Weigh 50 mg of p-chlorophenol into a 50 mL brown volumetric flask to prepare a 1 g / L p-chlorophenol stock solution, which is stored at -4°C. Then, take 2.5 mL of the stock solution and dilute it to 500 mL with ultrapure water to obtain a 5.0 mg / L solution.

[0095] 2) 50 mL of a 5 mg / L p-chlorophenol solution was placed in a 100 mL serum bottle, and then a certain amount of zero-valent iron was added to make the final concentration of zero-valent iron in the system 0.60 g / L.

[0096] 3) Add 0.25 mmol of EDTA to make the final EDTA concentration in the system 5.0 mmol / L.

[0097] 4) Add 0.25 mL of 1000 g / L MR-1 bacterial suspension to a concentration of 5 g / L. Stir on a magnetic stirrer at 400 rpm for 30 seconds to mix the solution evenly. Insert an aeration needle and rubber stopper and expose to oxygen for 1 hour.

[0098] 5) 1 mL of sample was taken at 0, 5, 10, 15, 20, 30, 40, 50, and 60 min, and 1 mL of methanol was added to stop the reaction. After mixing the solution, the supernatant was centrifuged and filtered through a 0.22 μm organic filter membrane into a liquid phase bottle. The concentration of 4-CP in the solution was determined by high performance liquid chromatography.

[0099] The specific chromatographic conditions were systematically optimized as follows: the flow rate was set at 0.6 mL / min; methanol-water mixture system (V / V = 7:3); the excitation wavelength was 280 nm; the column temperature was controlled at 35 ± 0.5 °C; the automatic sampler injection volume was 10 μL; and the measurement time was 12 min.

[0100] Examples 20-23

[0101] The technical solutions provided in Examples 20-23 are basically the same as the technical solution provided in Example 19, with the only difference being the volume of 1000 g / L MR-1 bacterial suspension added and its final concentration. See Table 5 for details.

[0102] Table 5

[0103] Example MR-1 bacterial suspension (mL) Final concentration of MR-1 (g / L) Example 20 0.5 10 Example 21 1 20 Example 22 1.5 30 Example 23 2 40

[0104] The degradation efficiency results of chlorophenol provided by the methods of Examples 19-23 are as follows: Figure 5 As shown in the figure, as the dosage of MR-1 bacterial suspension increased from 5 g / L to 40 g / L, the degradation efficiency of p-chlorophenol showed an upward trend.

[0105] Examples 24-27

[0106] The technical solutions provided in Examples 24-27 are basically the same as the technical solution provided in Example 2, with the only difference being that equal amounts of other bacterial species are used instead of Shewanella (MR-1), as shown in Table 6 for details.

[0107] Table 6

[0108]

[0109]

[0110] It should be noted that:

[0111] The culture methods and parameters for Escherichia coli (E. coli), Shewanella decoloris (S12), and Shewanella putrefaciens (SP200) used in Examples 24-26 were the same as those for Shewanella (MR-1) in Example 1.

[0112] The cultivation steps of Geobacter sulfurreducens (PCA) in Example 27 are as follows:

[0113] 1) Prepare 100× NB Salts, 1 mmol / L Na2SeO4, mineral trace elements, and 1 mmol / L vitamins in advance and store in a refrigerator at 4°C.

[0114] The 100×NB Salts solution is shown in Table 7:

[0115] Table 7

[0116]

[0117] The configuration of mineral trace elements is shown in Table 8:

[0118] Table 8

[0119]

[0120]

[0121] 2) Preparation of NBAF medium: 4.64 g of fumaric acid was weighed and added to approximately 800 mL of ultrapure water. 3 g of NaOH was then added and sonicated until completely dissolved. 1.8 g of NaHCO₃, 0.4327 g of Na₂CO₃, and 1.229 g of CH₃COONa were then added in that order. The pH was adjusted to 6.8-7.0 with 1 mol / L hydrochloric acid. The remaining reagents (1 mL of 1 mmol / L Na₂SeO₄, 10 mL of 100×NB Salts described in Table 7, 10 mL of the mineral trace elements described in Table 8, 15 mL of 1 mol / L vitamins, 0.1 g / LMgSO₄·7H₂O, and 0.04 g of CaCl₂·H₂O) were then added. The solids were stirred thoroughly to dissolve, and the volume was brought to 1 L with ultrapure water. The prepared culture medium was divided into dried 100 mL serum bottles, and a mixed gas of N2 / CO2 (volume ratio 80:20) was introduced for half an hour to remove oxygen in the water body and the top of the water body. The bottles were then sealed with butyl rubber stoppers and aluminum caps, sterilized in a high-pressure steam sterilizer (120°C, 20 min) and stored away from light for later use.

[0122] 3) Inoculation of PCA strain: The PCA bacterial suspension was enriched by centrifugation (4000 rpm, 15 min, 4°C), resuspended, and injected into sterilized and deoxygenated NBAF medium using a syringe filled with mixed gas on a clean bench. The culture was then placed in a constant temperature incubator for 3-4 days.

[0123] 4) Preparation of PCA bacterial suspension: The cultured PCA bacterial suspension was heated at 4°C and 6000 r / min. -1 The mixture was centrifuged for 10 minutes at 4°C, the supernatant was discarded, and the bacterial pellet was washed three times with 0.9 wt% sterile saline, then rinsed once with ultrapure water, and finally resuspended with ultrapure water to prepare a pure bacterial suspension.

[0124] The degradation ability of 4-CP by different strains in the presence of EDTA provided in Examples 24-27 is shown in Figure 6 It can be seen that, using the non-electroactive microorganism Escherichia coli (E. coli) as the control group, the study found that the degradation efficiency of 4-CP by MR-1, PCA, SP200 and S12 strains was significantly higher than that of the non-electroactive microorganism E. coli.

[0125] Example 28 This example selects a mixed bacterial liquid of MR-1 and PCA, both of which belong to dissimilatory iron-reducing bacteria, as a catalyst for the zero-valent iron aeration system to degrade p-chlorophenol, and includes the following steps in sequence:

[0126] 1) The preparation method of MR-1 bacterial suspension is the same as that in Example 1; the preparation method of PCA bacterial suspension is the same as that in Example 27.

[0127] 2) At room temperature, weigh 50 mg of p-chlorophenol into a 50 mL brown volumetric flask to prepare a 1 g / L p-chlorophenol stock solution, which was stored in a -4°C refrigerator. Subsequently, 2.5 mL of the stock solution was diluted to 500 mL with ultrapure water to prepare a 5.0 mg / L stock solution.

[0128] 3) Place 50 mL of a 5 mg / L p-chlorophenol solution in a 100 mL serum bottle. Add 0.03 g of zero-valent iron to a final concentration of 0.60 g / L. Add 0.25 mmol of EDTA to a final concentration of 5.0 mmol / L.

[0129] 4) Add a mixed bacterial solution with a mass concentration ratio of c(MR-1) to c(PCA) of 2:1, stir on a magnetic stirrer at 400 rpm for 30 seconds to mix the solution evenly, insert an aeration needle and rubber stopper, and expose to oxygen for 1 hour.

[0130] 5) 1 mL of sample was taken at 0, 5, 10, 15, 20, 30, 40, 50, and 60 min, and 1 mL of methanol was added to stop the reaction. After mixing the solution, the supernatant was centrifuged and filtered through a 0.22 μm organic filter membrane into a liquid phase bottle. The concentration of 4-CP in the solution was determined by high performance liquid chromatography.

[0131] The specific chromatographic conditions were systematically optimized as follows: the flow rate was set at 0.6 mL / min; methanol-water mixture system (V / V = 7:3); the excitation wavelength was 280 nm; the column temperature was controlled at 35 ± 0.5 °C; the automatic sampler injection volume was 10 μL; and the measurement time was 12 min.

[0132] Examples 29-32

[0133] The technical solutions provided in Examples 29-32 are basically the same as the technical solution provided in Example 28, except that different mass concentration ratios of c(MR-1) and c(PCA) are used. For details, see Table 9.

[0134] Table 9

[0135] c(MR-1):c(PCA) Example 29 5:1 Example 30 4:1 Example 31 3:1 Example 32 1:1

[0136] The degradation efficiency of MR-1 and PCA with different mass concentration ratios provided in Examples 29-32 is shown in the table below. Figure 7 ,pass Figure 7 It can be seen that as the concentration ratio of MR-1 bacteria to PCA bacteria (c(MR-1):c(PCA)) decreases, the degradation efficiency of 4-CP increases accordingly.

[0137] Examples 33-36

[0138] The technical solution provided in this example is basically the same as the technical solution provided in Example 28. The only difference is the added mass of zero-valent iron and its final concentration. See Table 10 for details.

[0139] Table 10

[0140] Example Added mass of zero-valent iron (g) Final concentration of zero-valent iron (g / L) Example 33 0.004 0.08 Example 34 0.005 0.10 Example 35 0.01 0.20 Example 36 0.02 0.40

[0141] The degradation efficiency results of chlorophenol provided by the method of Example 36-36 are as follows Figure 8 As shown in the figure, as the dosage of zero-valent iron increased from 0.08 g / L to 0.60 g / L, the corresponding 4-CP degradation efficiency increased. The possible reason is that under the optimal ratio of c(MR-1):c(PCA), Fe 2+ The release rate is increased to ensure that the Fenton reaction continues to proceed efficiently. Therefore, the present invention determines that the dosage of zero-valent iron is 0.60g / L.

[0142] Example 37

[0143] The technical solution provided in this example is basically the same as the technical solution provided in Example 28, the only difference being the added molar amount of EDTA and its final concentration. See Table 11 for details.

[0144] Table 11

[0145] Example Molar amount of EDTA added (mmol) Final EDTA concentration (mmol / L) Example 18 0.025 0.5 Example 15 0.05 1.0 Example 16 0.075 1.5 Example 17 0.1 2.0

[0146] The degradation efficiency results of chlorophenol provided by the method of Example 36-36 are as follows Figure 9 As shown in the figure, when the EDTA concentration increases from 0.5mmol / L to 5mmol / L, the degradation rate of chlorophenol in the enhanced zero-valent iron aeration system is better.

[0147] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. For those skilled in the art, changes or replacements that can be easily thought of are also considered to be within the protection scope of the present invention.

Claims

1. An electroactive microbial system for removing para-chlorophenol, characterized in that: The composition includes the following: zero-valent iron 0.08g / L-0.60g / L, exogenous substances 0.5-5.0mmol / L, and electroactive microbial strains 5-40g / L; The electroactive microbial strain is at least one of Shewanella decolorizing S12, Shewanella putrefaciens SP200, Shewanella MR-1, and Geobacter sulfurreducens PCA.

2. The electroactive microbial system for removing para-chlorophenol according to claim 1, characterized in that: The exogenous substance is one of ethylenediaminetetraacetic acid, riboflavin, humic acid, lactic acid, cytochrome c and acetic acid.

3. The electroactive microbial system for removing para-chlorophenol according to claim 1, characterized in that: The electroactive microbial strain is Shewanella MR-1.

4. The electroactive microbial system for removing para-chlorophenol according to claim 1, wherein: The electroactive microbial strains are a combination of Shewanella MR-1 and Geobacter sulfurreducens PCA.

5. The electroactive microbial system for removing para-chlorophenol according to claim 4, characterized in that: The mass ratio of the Shewanella MR-1 to the Geobacter sulfurreducens PCA is 1-5:

1.

6. The electroactive microbial system for removing para-chlorophenol according to claim 5, characterized in that: The mass ratio of the Shewanella MR-1 and the Geobacter sulfurreducens PCA is 2:

1.

7. The electroactive microbial system for removing para-chlorophenol according to claim 4, characterized in that: The source material is ethylenediaminetetraacetic acid.

8. A method for removing parachlorophenol, characterized in that, The electroactive microbial system for removing para-chlorophenol according to claim 1 is used to remove the para-chlorophenol under oxygen exposure conditions.

9. The method for removing p-chlorophenol using an electroactive microbial enhanced aeration system according to claim 8, characterized in that: The method includes the following steps in sequence: 1) resuscitating and culturing the electroactive microbial strains to prepare an electroactive microbial suspension; 2) The exogenous substance zero-valent iron in the electroactive microbial suspension prepared in step 1) was added to the solution containing p-chlorophenol, and after uniform mixing, an aeration needle and a rubber stopper were inserted, and oxygen was exposed for 1 hour.

10. The method for removing p-chlorophenol using an electroactive microbial enhanced aeration system according to claim 9, wherein: The concentration of p-chlorophenol is 5.0 mg / L; The system has a zero-valent iron concentration of 0.08 g / L-0.60 g / L, an exogenous substance concentration of 0.5-5.0 mmol / L, and an electroactive microbial strain concentration of 5-40 g / L; and an oxygen exposure rate of 1-8 L / min. The system consists of an electroactive microbial suspension, exogenous substances, zero-valent iron and a solution containing p-chlorophenol.

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