Device for degrading mesotrione pesticide by using double-chamber bioelectrochemical system and degradation method thereof

Abstract

The invention discloses a device for degrading mesotrione pesticide by using a double-chamber bioelectrochemical system and a degradation method thereof, and relates to the field of degradation of mesotrione pesticide wastewater. The device comprises an anode system and a cathode system, wherein mesotrione pollutants are positioned in the cathode system. According to the method disclosed by the invention, the bioelectrochemical reduction technology is utilized in a cathode system, and the mesotrione pesticide wastewater treatment is enhanced under the action of constant voltage through the synergistic effect of electrophilic microorganisms of a biological cathode and an electrode. The method has the characteristics of simplicity in operation, low cost, low energy consumption and high degradation efficiency. The mesotrione pesticide-containing soil or water pollution remediation method is suitable for mesotrione pesticide-containing soil or water pollution remediation.

Description

Technical Field

[0001] The invention relates to the field of degradation of mesotrione pesticide wastewater, and in particular to a method for degrading the pesticide mesotrione by utilizing a double-chamber bioelectrochemical system. Background Art

[0002] With the growth of population, human demand for food is increasing day by day. Therefore, in order to reduce the impact of weeds on crops and ensure crop yield and quality, pesticides have become an indispensable part of the agricultural production process. Although pesticides ensure high grain yields, a small part of the pesticides are absorbed by plants during use, and long-term and large-scale application will lead to a large amount of pesticide residues in the soil. Moreover, a large part of the pesticides remaining in the soil enter the water environment through farmland drainage or irrigation drainage, thus posing a threat to the ecosystem and human health. Mesotrione is stable under light, has the characteristics of high water solubility, strong fluidity and long half-life. It may pollute agricultural soil and water environment during use, posing a major challenge to agricultural production and ecological safety. Therefore, it is crucial to seek a green and efficient method to accelerate the removal of residual mesotrione in the environment. Summary of the invention

[0003] In order to solve the technical problem of ecological harm caused by mesotrione residues to soil and water, the present invention provides a device for degrading mesotrione pesticide using a double-chamber bioelectrochemical system and a degradation method thereof.

[0004] A device for degrading mesotrione pesticide by using a double-chamber bioelectrochemical system comprises a bioanode, a reference electrode, a cation exchange membrane, a biocathode, a reactor, a direct current power supply and a resistor. The cation exchange membrane separates the reactor into an anode chamber and a cathode chamber. Water inlets are arranged on the tops of the anode chamber and the cathode chamber, and water outlets are arranged on the front walls of the anode chamber and the cathode chamber. The reference electrode is arranged in the anode chamber. Glucose and an electrolyte solution are contained in the anode chamber, and glucose, mesotrione and an electrolyte solution are contained in the cathode chamber. The bioanode is located in the anode chamber, and the biocathode is located in the cathode chamber. Both the bioanode and the biocathode are made of carbon fiber brushes. The bioanode is connected to the positive electrode of the direct current power supply through a wire, and the biocathode is connected to the negative electrode of the direct current power supply through a wire, and a resistor is connected in series.

[0005] The degradation method of the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is specifically carried out in the following steps:

[0006] 1. A device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is used, glucose and electrolyte solution are injected through the water inlet of the anode chamber, glucose, mesotrione and electrolyte solution are injected through the water inlet of the cathode chamber, and then sludge is inoculated into the anode chamber and the cathode chamber;

[0007] 2. operating the device for degrading the mesotrione pesticide using a dual-chamber bioelectrochemical system as described in step 1 in a sequential batch manner, and directional domesticating electroactive microorganisms on the bioanode and the biocathode to form a stable biofilm;

[0008] 3. After the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is stably operated through step 2, the voltage of the DC power supply and the concentration of glucose in the cathode chamber are adjusted to degrade mesotrione.

[0009] The method of operating the device in a batch manner in step 2 is specifically to synchronously acclimate the anode biofilm and the cathode biofilm in a gradient, for a total of 3 cycles, each acclimatization cycle is 6 days, and the voltage is 0.50V.

[0010] The device of the present invention is composed of an anode system and a cathode system, and the mesotrione pollutant is located in the cathode system. The method of the present invention utilizes bioelectrochemical reduction technology in the cathode system, and strengthens the treatment of mesotrione pesticide wastewater under the action of constant voltage through the synergistic effect of electrodeophilic microorganisms and electrodes in the biological cathode. It is suitable for the remediation of soil or water pollution containing mesotrione pesticide.

[0011] The present invention couples biotechnology and electrochemical technology. Under weak electrical stimulation, the electrode (carbon fiber brush) will carry a large number of functional microorganisms to achieve the purpose of deep detoxification and mineralization of difficult-to-degrade pollutants. The present invention utilizes the influence of applied voltage and co-substrate (glucose) concentration on the degradation performance of mesotrione to achieve the purpose of improving the degradation efficiency of mesotrione, thereby realizing the mineralization of pollutants.

[0012] The bioelectrochemical system (BES) is a process based on biotechnology coupled with electrochemical technology. Under weak electrical stimulation, a large number of electroactive microorganisms are attached to the anode and cathode, which can reduce the overpotential of the electrochemical reaction. The microorganisms in the anode undergo oxidation reactions, which can consume simple substrates (such as glucose, sodium acetate, crop straw, etc.) or complex substrates (such as pesticides, phenolic compounds, etc.) to produce more electrons and protons. In a closed loop, the cathode receives the electrons transferred by the anode and undergoes a reduction reaction to achieve the removal of difficult-to-degrade pollutants or convert difficult-to-degrade pollutants into easily degradable substances. Therefore, the treatment efficiency of the bioelectrochemical system is superior to that of traditional biological treatment technology and electrochemical treatment technology. This system has great potential in removing difficult-to-degrade organic pollutants due to its advantages such as high degradation efficiency, good universality, short cycle, economic feasibility and no secondary pollution.

[0013] Beneficial effects of the present invention:

[0014] The present invention combines electrochemical technology with biological treatment processes, and the reactor adopts a simple dual-chamber reactor assembly method. It has the following advantages: ① The anode chamber and cathode chamber of the dual-chamber reactor are separated by a cation exchange membrane, which avoids the stress effect of the difficult-to-degrade pollutants in the cathode chamber on the electroactive microorganisms in the anode chamber. Therefore, the electroactive microorganisms in the anode chamber can consume simple organic matter to generate electricity, and can continuously transfer electrons and protons to the cathode. The cathode receives the electrons and protons transferred by the anode, realizes the reduction and detoxification treatment of mesotrione, and improves the biodegradability of difficult-to-degrade wastewater. ② Using a dual-chamber configuration reactor, the microorganisms in the anode chamber focus on electricity generation, and the microorganisms in the cathode chamber focus on degradation. This clear division of labor is conducive to the stable operation of the bioelectrochemical system, achieving the purpose of efficiently degrading mesotrione, and avoiding the complexity of the anode chamber assuming multiple functions.

[0015] The electrode material used in the dual-chamber reactor of the present invention is a carbon fiber brush, which has a high specific surface area and good biocompatibility, can provide more attachment sites, promote the electroactive microorganisms and functional microorganisms in the anode and cathode to adhere and grow on the carbon fiber surface, and form a stable biofilm. In addition, the carbon fiber brush also has excellent electrical conductivity, and can quickly transfer the electrons generated by the electroactive microorganisms in the anode to the cathode, thereby being used by the electrode-loving microorganisms or other functional microorganisms in the cathode, thereby accelerating the removal of mesotrione. Compared with electrode materials such as carbon cloth, the carbon fiber brush is low in cost and has significant advantages in practical applications.

[0016] The present invention also has the characteristics of simple operation, low energy consumption, strong practicality, etc., and is conducive to the construction of a large double-chamber reactor to achieve deep removal of difficult-to-degrade pollutants in farmland drainage or irrigation drainage to achieve the purpose of mineralization.

[0017] The invention is used for degrading mesotrione pesticide wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system as described in Example 1;

[0019] Figure 2 This is a graph showing the degradation performance of mesotrione in Example 1;

[0020] Figure 3 This is a graph showing the degradation performance of mesotrione in Example 2. DETAILED DESCRIPTION

[0021] Specific implementation method one: This implementation method is a device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system, the device includes a bioanode 1, a reference electrode 2, a cation exchange membrane 3, a biocathode 4, a reactor 5, a DC power supply and a resistor, the cation exchange membrane 3 separates the reactor 5 into an anode chamber and a cathode chamber, the tops of the anode chamber and the cathode chamber are both arranged with water inlets, the front walls of the anode chamber and the cathode chamber are both arranged with water outlets, the reference electrode 2 is arranged in the anode chamber, the anode chamber contains glucose and an electrolyte solution, the cathode chamber contains glucose, mesotrione and an electrolyte solution, the bioanode 1 is located in the anode chamber, the biocathode 4 is located in the cathode chamber, the bioanode 1 and the biocathode 4 are both made of carbon fiber brushes, the bioanode is connected to the positive electrode of the DC power supply through a wire, the biocathode is connected to the negative electrode of the DC power supply through a wire, and a resistor is connected in series.

[0022] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that the resistor is 20Ω. Other aspects are the same as the specific implementation method 1.

[0023] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the reference electrode 2 is a Hg / Hg2Cl2 electrode. The rest is the same as specific implementation method 1 or 2.

[0024] Specific embodiment 4: This embodiment is a degradation method of a device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system, which is specifically carried out in the following steps:

[0025] 1. A device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is used, glucose and electrolyte solution are injected through the water inlet of the anode chamber, glucose, mesotrione and electrolyte solution are injected through the water inlet of the cathode chamber, and then sludge is inoculated into the anode chamber and the cathode chamber;

[0026] 2. The device for degrading the mesotrione pesticide using a dual-chamber bioelectrochemical system as described in step 1 is operated in a sequential batch manner to domesticate the electroactive microorganisms on the bioanode 1 and the biocathode 4 to form a stable biofilm;

[0027] 3. After the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is stably operated through step 2, the voltage of the DC power supply and the concentration of glucose in the cathode chamber are adjusted to degrade mesotrione.

[0028] Specific embodiment 5: This embodiment differs from specific embodiment 4 in that: in step 1, the electrolyte solution in the cathode chamber and the anode chamber is a phosphate solution, wherein the concentration of disodium hydrogen phosphate is 11.55 g L -1 , sodium dihydrogen phosphate concentration is 2.77 g L -1 The rest is the same as the fourth specific implementation method.

[0029] Specific embodiment 6: This embodiment is different from specific embodiment 4 or 5 in that: the concentration of glucose in the anode chamber in step 1 is 1000 mg L -1 , the concentration of glucose in the cathode chamber is 250 mg L -1 The rest is the same as the fourth or fifth embodiment.

[0030] Specific implementation method 7: This implementation method is different from specific implementation methods 4 to 6 in that the sludge inoculated in step 1 is the sludge from the secondary sedimentation tank of the sewage treatment plant. The rest is the same as specific implementation methods 4 to 6.

[0031] Specific embodiment 8: This embodiment is different from specific embodiments 4 to 7 in that: the method of operating the device in a batch manner in step 2 is specifically to synchronously acclimate the anode biofilm and the cathode biofilm in a gradient, for a total of 3 cycles, each acclimatization cycle is 6 days, and the voltage is 0.50 V. The rest is the same as specific embodiments 4 to 7.

[0032] Specific implementation method 9: This implementation method is different from specific implementation methods 4 to 8 in that: the voltage adjustment range of the DC power supply in step 3 is 0 to 0.75 V. The rest is the same as specific implementation methods 4 to 8.

[0033] Specific embodiment 10: This embodiment differs from any one of specific embodiments 4 to 9 in that: Step 3 adjusts the concentration of glucose in the cathode chamber to 0-750 mg L -1 The rest is the same as any one of the fourth to ninth embodiments.

[0034] The content of the present invention is not limited to the content of the above-mentioned embodiments. The combination of one or several specific embodiments can also achieve the purpose of the invention.

[0035] Embodiment 1:

[0036] The present embodiment provides a device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system. The device includes a bioanode 1, a reference electrode 2, a cation exchange membrane 3, a biocathode 4, a reactor 5, a DC power supply and a resistor. The cation exchange membrane 3 separates the reactor 5 into an anode chamber and a cathode chamber. Water inlets are arranged on the tops of the anode chamber and the cathode chamber, and water outlets are arranged on the front walls of the anode chamber and the cathode chamber. The reference electrode 2 is arranged in the anode chamber. The anode chamber contains a glucose solution, and the cathode chamber contains a mixed solution of glucose and mesotrione. The bioanode 1 is located in the anode chamber, and the biocathode 4 is located in the cathode chamber. The bioanode 1 and the biocathode 4 are both made of carbon fiber brushes. The bioanode is connected to the positive electrode of the DC power supply through a wire, and the biocathode is connected to the negative electrode of the DC power supply through a wire, and a resistor is connected in series.

[0037] The resistor is 20Ω.

[0038] The reference electrode 2 is a Hg / Hg2Cl2 electrode.

[0039] The degradation method of the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is specifically carried out in the following steps:

[0040] 1. Take a device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system, inject glucose and electrolyte solution through the anode chamber water inlet, and the glucose concentration is 1000 mg L -1 Glucose, mesotrione and electrolyte solution were injected through the cathode chamber water inlet, where the concentration of mesotrione was 5 mg L -1 , the concentration of glucose is 250 mg L -1 The electrolyte solution in the anode chamber and the cathode chamber is 62 mL of phosphate solution, in which the concentration of disodium hydrogen phosphate is 11.55 g L -1 , sodium dihydrogen phosphate concentration is 2.77 g L -1 ; Then 20mL of sludge from the secondary sedimentation tank of the sewage treatment plant was inoculated into both the anode chamber and the cathode chamber;

[0041] 2. Under room temperature, the device for degrading the mesotrione pesticide using a dual-chamber bioelectrochemical system described in step 1 is operated in a sequential batch manner to domesticate the electroactive microorganisms on the bioanode 1 and the biocathode 4 to form a stable biofilm;

[0042] The method of operating the device in a sequential batch manner is specifically as follows: synchronously acclimating the anode biofilm and the cathode biofilm in a gradient manner for a total of 3 cycles, each acclimation cycle is 6 days, and the voltage is 0.50V;

[0043] 3. After the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is stably operated through step 2, the voltage of the DC power supply and the concentration of glucose in the cathode chamber are adjusted to degrade mesotrione.

[0044] Step 3: Adjust the glucose concentration in the cathode chamber to 250 mg L -1 , operate the device to degrade mesotrione, and the voltage of the DC power supply is 0V, 0.25V, 0.35V, 0.50V, and 0.75V respectively for parallel experiments, which are run for 24 hours respectively.

[0045] The degradation performance of mesotrione in this example is shown in the figure Figure 2 shown.

[0046] Depend on Figure 2It can be seen that different applied voltages have a significant effect on the removal efficiency of mesotrione. The results show that as the applied voltage increases from 0V to 0.75V, the removal efficiency of mesotrione gradually increases. When the applied voltages are 0V, 0.25V, 0.35V, 0.50V, and 0.75V, the removal efficiencies of mesotrione are 80.81±2.92%, 98.10±0.46%, 99.91±0.07%, 99.76±0.41%, and 99.85±0.13%, respectively. This shows that the bioelectrochemical system can achieve a good degradation effect on mesotrione. When the applied voltage increases to 0.75V, the removal efficiency of mesotrione reaches the maximum. Compared with 0V, the removal efficiency of mesotrione increases by 20%, indicating that a higher applied voltage can enhance the removal of mesotrione. This may be because the appropriate weak electrical environment can effectively stimulate microorganisms to enhance their electrical activity and promote electron transfer. After applying an external voltage, it can provide effective electrons for the cathode reduction reaction and accelerate the efficiency of electron transfer, ultimately significantly improving the degradation of target pollutants.

[0047] Embodiment 2:

[0048] The present embodiment is different from the first embodiment in that: in step 3, the voltage of the DC power supply is adjusted to 0.5 V, the device is operated to degrade mesotrione, and the concentration of glucose in the cathode chamber is adjusted to 0 mg L -1 , 250mg L -1 , 500mgL -1 , 750mg L -1 Parallel experiments were performed and run for 24 h each.

[0049] The degradation performance of mesotrione in this example is shown in the figure Figure 3 shown.

[0050] Depend on Figure 3 It can be seen that as the glucose concentration in the BES cathode solution increases from 0 to 750 mg L -1 , the removal efficiency of mesotrione at the cathode showed a gradually increasing trend, and at 24h, the removal efficiency of mesotrione could reach about 100%. This shows that the bioelectrochemical system can have a very good effect on the removal of mesotrione and can enhance the reduction and detoxification of mesotrione. In addition, the electrons required for the efficient removal of mesotrione come partly from the electrons transferred from the electroactive bacteria in the anode to the cathode, and partly from the electrons produced by the functional microorganisms in the cathode metabolizing glucose. A higher concentration of glucose can provide sufficient electrons for the reduction reaction of mesotrione and accelerate the removal of mesotrione. Therefore, a glucose concentration of 750mg L -1 .

[0051] In summary, in the bipolar chamber bioelectrochemical system device, the fermentation bacteria in the anode chamber can decompose glucose into small molecular organic acids such as acetic acid and propionic acid, and the electrons and carbon sources generated in the fermentation process can be used by electroactive bacteria to promote electron transfer. Due to the synergistic effect between electroactive bacteria and fermentation bacteria, a large amount of electrons are enriched in the anode, and the electrons required for the reduction reaction (degradation of mesotrione) can be continuously transferred to the cathode. The functional microorganisms in the cathode chamber can not only use the electrons transferred from the anode for metabolic activities, but also rely on the electroactive bacteria in the cathode to strengthen the electron transfer, accelerate the overall metabolic activity of the cathode microorganisms, and thus efficiently remove mesotrione. At the cathode, mesotrione mainly undergoes keto group cleavage and nitro group reduction, which can convert part of mesotrione into easily degradable or low-toxic intermediates, and the other part is completely converted into CO2 and H2O, ultimately achieving the purpose of detoxification and mineralization of mesotrione. Therefore, the mutual cooperation of multiple functional microorganisms is a key factor in maintaining the efficient degradation of mesotrione. This experiment can achieve the treatment of difficult-to-degrade pesticide wastewater, and has the characteristics of high removal efficiency, simple operation and good stability, providing a theoretical basis and technical foundation for the efficient treatment of pesticides remaining in farmland drainage or irrigation drainage.

Claims

1. A device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system, characterized in that The device comprises a biological anode (1), a reference electrode (2), a cation exchange membrane (3), a biological cathode (4), a reactor (5), a direct current power supply and a resistor. The cation exchange membrane (3) divides the reactor (5) into an anode chamber and a cathode chamber. Water inlets are arranged at the tops of the anode chamber and the cathode chamber, and water outlets are arranged at the front walls of the anode chamber and the cathode chamber. The reference electrode (2) is arranged in the anode chamber. Glucose and an electrolyte solution are contained in the anode chamber, and glucose, mesotrione and an electrolyte solution are contained in the cathode chamber. The biological anode (1) is located in the anode chamber, and the biological cathode (4) is located in the cathode chamber. The biological anode (1) and the biological cathode (4) are both made of carbon fiber brushes. The biological anode is connected to the positive electrode of the direct current power supply through a wire, and the biological cathode is connected to the negative electrode of the direct current power supply through a wire, and a resistor is connected in series.

2. The device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 1, characterized in that The resistor is 20Ω.

3. The device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 1, characterized in that The reference electrode (2) is a Hg / Hg2Cl2 electrode.

4. The method for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system as claimed in claim 1, characterized in that The method is specifically carried out in the following steps:

1. A device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is used, glucose and electrolyte solution are injected through the water inlet of the anode chamber, glucose, mesotrione and electrolyte solution are injected through the water inlet of the cathode chamber, and then sludge is inoculated into the anode chamber and the cathode chamber; 2. The device for degrading the mesotrione pesticide using a dual-chamber bioelectrochemical system described in step 1 is operated in a sequential batch manner, and the electroactive microorganisms are directed to be domesticated on the bioanode (1) and the biocathode (4) to form a stable biofilm; 3. After the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system is stably operated through step 2, the voltage of the DC power supply and the concentration of glucose in the cathode chamber are adjusted to degrade mesotrione.

5. The method for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 4, characterized in that Step 1: The electrolyte solution in the cathode chamber and the anode chamber is a phosphate solution, wherein the concentration of disodium hydrogen phosphate is 11.55 g L -1 , sodium dihydrogen phosphate concentration is 2.77 g L -1 .

6. The degradation method of the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 4, characterized in that Step 1: The concentration of glucose in the anode chamber is 1000 mg L -1 , the concentration of glucose in the cathode chamber is 250 mg L -1 .

7. The method for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 4, characterized in that The sludge inoculated in step 1 is the sludge from the secondary sedimentation tank of the sewage treatment plant.

8. The method for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 4, characterized in that The method of operating the device in a batch manner in step 2 is specifically to synchronously acclimate the anode biofilm and the cathode biofilm in a gradient, for a total of 3 cycles, each acclimatization cycle is 6 days, and the voltage is 0.50V.

9. The method for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 4, characterized in that Step 3: The voltage adjustment range of the DC power supply is 0-0.75V.

10. The degradation method of the device for degrading mesotrione pesticide using a dual-chamber bioelectrochemical system according to claim 4, characterized in that Step 3: Adjust the concentration of glucose in the cathode chamber to 0-750 mg L -1 .

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