Apparatus and method for accelerating degradation of pollutants by microorganisms in redox oscillation region based on electric stimulation

Abstract

The application discloses a device and method for accelerating redox oscillation region microbial advanced oxidation degradation of pollutants based on electric stimulation, and belongs to the field of bioelectrochemistry and advanced oxidation technology. The application provides a device for accelerating redox oscillation region microbial advanced oxidation degradation of pollutants based on electric stimulation, which comprises a computer, a data line, an electrochemical workstation, a wire, a glassy carbon electrode, a gas guide pipe, an aeration head, a screw neck bottle, a sealing plug with three Φ6 through holes, a nitrogen gas cylinder and an air gas cylinder. The application can accelerate the degradation of pollutants by strengthening microbial respiration and accelerating dissimilatory iron reduction and hydroxyl radical generation through electric stimulation. Unlike traditional microbial electrochemical methods that promote pollutant decomposition through electrode reaction, the application can significantly reduce the high requirements of bioelectrochemical methods on electrode materials and power consumption, and can provide a new method for the application of microbial electrochemistry in pollution remediation.

Description

Technical Field

[0001] This invention belongs to the field of bioelectrochemistry and advanced oxidation technology, specifically relating to a device and method for the advanced oxidation degradation of pollutants by microorganisms based on electrically stimulated redox oscillation zones. Background Technology

[0002] Microbial electrochemical systems have been widely reported for enhancing wastewater / organic solid waste treatment, in-situ remediation of soil and wetlands, and other applications. In these systems, pollutants are decomposed on electrodes through anodic oxidation coupled with cathodic reduction by microorganisms, thereby enhancing pollutant removal efficiency. However, the electrode reactions are energy-intensive, and the applied voltage must overcome the thermodynamic barrier (Ea) between the cathode and anode potentials. 阴极 >E 阳极 However, it is also necessary to overcome the influence of system resistance and overpotential. In particular, soil / wetland has a relatively high resistance, and the large-scale application of microbial electrochemical systems in in-situ remediation of soil and wetlands is relatively limited.

[0003] Microbial advanced oxidation (AEO) is a newly discovered mechanism for generating reactive oxygen species and decomposing pollutants in wetlands, soils, and intertidal zones. First named by us, AEO is based on the production of hydroxyl radicals by extracellular respiration of microbial cells, exhibiting periodic variations under both anaerobic and aerobic conditions. To date, no devices or methods have been reported for using electrical stimulation to enhance microbial AEO for pollutant degradation. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an apparatus and method for the advanced oxidation degradation of pollutants by microorganisms in the redox oscillation zone based on electrical stimulation. The micro-electric field stimulation is used in the biological advanced oxidation to increase the metabolic rate of iron-reducing bacteria, enhance the extracellular electron transfer of iron-reducing bacteria, and improve the effective generation of hydroxyl radicals, thereby forming a biological advanced oxidation to remove pollutants rather than through electrode reactions, thus significantly reducing energy consumption.

[0005] The objective of this invention is achieved through the following means:

[0006] This invention provides a device for the advanced oxidative degradation of pollutants by microorganisms in an accelerated oxidation-reduction oscillating zone based on electrical stimulation. The device includes a computer, a data cable, an electrochemical workstation, wires, electrodes, an air delivery tube, an aeration head, a threaded bottle, a sealing plug with three Φ6 through holes, a nitrogen cylinder, and an air cylinder. The threaded bottle has a water inlet at the bottom and an electrode insertion port on its side bottom. The threaded bottle and the sealing plug with three through holes are assembled into a reaction vessel. The positive and negative electrodes are inserted into the threaded bottle through the through holes of the sealing plug at the top and the electrode insertion port on the side bottom, respectively, and are connected to the positive and negative terminals of the electrochemical workstation through wires. The electrochemical workstation is connected to the computer via a data cable. The nitrogen cylinder and the air cylinder are connected to the air delivery tube, which extends into the bottom of the threaded bottle through the through holes of the sealing plug. An aeration head is connected to the end of each air delivery tube.

[0007] Based on the above technical solution, further, the distance between the two electrodes is controlled to 3-5cm to prevent excessive electric field strength from being detrimental to the growth of microorganisms.

[0008] Based on the above technical solution, furthermore, both the nitrogen cylinder and the air cylinder are equipped with flow meters to control the flow rate of the introduced gas.

[0009] Based on the above technical solution, the electrode is further described as a glassy carbon electrode.

[0010] Another aspect of the present invention provides a method for the advanced oxidative degradation of pollutants by microorganisms in an accelerated redox oscillation zone based on electrical stimulation. The method is implemented using the aforementioned apparatus for the advanced oxidative degradation of pollutants by microorganisms in an accelerated redox oscillation zone based on electrical stimulation, and includes the following steps:

[0011] (1) After drying, grinding and screening, the sludge is activated for 2-4 months;

[0012] (2) Add the activated sludge obtained in step (1) into a wire-mouth bottle, set a voltage of 0.5-1.0V on the electrochemical workstation, generate an electric field through the electrodes connected by wires, electrically stimulate the electroactive microorganisms in the sludge, and record the current intensity in real time on the computer.

[0013] (3) Control the flow of nitrogen or air into the nitrogen cylinder and air cylinder. Flow nitrogen for 12 hours and air for 12 hours every day until the pollutants are completely degraded and the reaction ends.

[0014] Based on the above technical solution, further, the activation in step (1) is carried out using glucose wastewater.

[0015] Based on the above technical solution, further, in step (2), the internal temperature of the threaded bottle is controlled at 28-30℃.

[0016] Based on the above technical solution, further, in step (2), the pH value inside the swivel bottle is controlled between 7.5 and 8.5.

[0017] Based on the above technical solution, further, in step (2), the hydraulic residence time of the sprue is controlled between 5 and 7 days.

[0018] Based on the above technical solution, further, the gas flow rate in step (3) is 0.5 to 1.5 L / h.

[0019] This invention also protects the application of the above-mentioned method for the advanced oxidative degradation of pollutants by microorganisms in redox oscillation zones based on electrical stimulation in wetland remediation.

[0020] Based on the above technical solution, the application further includes the removal of nitrophenol from wetlands.

[0021] The mechanism of the method for the advanced oxidative degradation of pollutants by microorganisms in the redox oscillation zone based on electrical stimulation in this invention is as follows:

[0022] 1. Microbial extracellular electron transport is the process by which electroactive microorganisms transfer electrons generated by intracellular oxidative electron donors to extracellular electron acceptors through the respiratory chain, achieving electron acceptor reduction while maintaining microbial growth. Microbial advanced oxidation is based on microbial extracellular electron transport, inducing the generation of reactive oxygen species (ROS) through the alternating coupling of aerobic and anaerobic iron respiration. Specifically, under aerobic conditions, electrons transferred during extracellular respiration by aerobic or facultative bacteria are captured by oxygen, thus generating ROS. Under anaerobic conditions, facultative bacteria with extracellular respiration transfer electrons to iron(III) minerals in the extracellular environment. The resulting iron(II) can react with superoxide anions and hydrogen peroxide to generate highly oxidizing hydroxyl radicals, thereby accelerating the mineralization of recalcitrant pollutants.

[0023] 2. The method of the present invention uses micro-electric field stimulation to increase the metabolic rate of iron-reducing bacteria and enhance the abundance of iron-reducing bacteria in polluted wetlands. It is expected to improve the treatment effect of wetland pollutants by enhancing biological advanced oxidation, rather than removing pollutants through electrode reactions, thus significantly reducing energy consumption.

[0024] The advantages of this invention over the prior art are as follows:

[0025] 1. The method of accelerating the advanced oxidative degradation of pollutants by microorganisms in a redox oscillating zone based on electrostimulation of the present invention is characterized by the following: First, electrostimulation can improve the electroactivity of the microbial community, which is conducive to promoting the transfer of intracellular electrons to extracellular electron acceptors, accelerating the reduction of dissimilar iron, and resulting in a higher iron(II) content in the supernatant of the electrostimulated group. This provides a sufficient catalyst for the generation of hydroxyl radicals in bio-advanced oxidation, increases the yield of bio-advanced oxidation hydroxyl radicals, and promotes pollutant degradation. In addition, bacteria with extracellular electron transport capabilities are enriched under electrostimulation, and the enrichment of extracellular respiratory microorganisms also provides favorable conditions for the reduction of dissimilar iron in the system. Under the action of electrostimulation, the reduction of dissimilar iron and the generation of hydroxyl radicals in the redox oscillating environment are accelerated, accelerating the degradation of organic pollutants. Electrostimulation causes polarization of amide groups in protein substances, thereby increasing the electroactivity of sediments and promoting the transfer of extracellular electrons by microorganisms. The present invention verifies the feasibility of enhancing microbial respiration through electrostimulation, and thus is expected to provide a new strategy for the promotion and application of bioelectrochemical technology in the remediation of non-point source wetland pollution.

[0026] 2. Unlike non-biological advanced oxidation processes, the reactive oxygen species of the present invention are generated by microbial respiration rather than the addition of exogenous chemical substances, and no reactive oxygen species are detected in the cathodic reduction process of the present invention.

[0027] 3. The innovation of this invention lies in utilizing electrical stimulation to promote extracellular respiration in microorganisms to generate hydroxyl radicals. The basic mechanism is that an electric field induces the polarization of microbial respiratory enzymes, accelerating proton-coupled electron transport within the respiratory chain, thereby increasing ATP levels and electron transport, and accelerating the generation of hydroxyl radicals. This invention provides a completely new perspective for the application of microbial electrochemical methods in wetland remediation. Attached Figure Description

[0028] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0029] Figure 1 This is a schematic diagram of the device for the advanced oxidation degradation of pollutants by microorganisms in an accelerated oxidation-reduction oscillation zone based on electrical stimulation, wherein: 1-laptop, 2-data cable, 3-electrochemical workstation, 4-wire, 5-glassy carbon electrode, 6-air guide tube, 7-aeration head, 8-thread bottle, 9-sealing plug with three Φ6 through holes, 10-flow meter, 11-nitrogen cylinder, 12-air cylinder. Detailed Implementation

[0030] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0031] Example 1

[0032] This invention provides a method for the advanced oxidative degradation of pollutants by microorganisms in an accelerated redox oscillating region based on electrical stimulation, and the apparatus for this method is described below. Figure 1 The system includes a laptop (1), a data cable (2), an electrochemical workstation (3), wires (4), a glassy carbon electrode (5), a gas delivery tube (6), an aeration head (7), a threaded bottle (8), a sealing plug (9) with three Φ6 through holes (10), a flow meter (11), a nitrogen cylinder (11), and an air cylinder (12). The threaded bottle (8) has a water inlet at its bottom and a glassy carbon electrode insertion port on its side bottom. The threaded bottle (8) and the sealing plug (9) with three Φ6 through holes are assembled into a reaction vessel. Sludge for degrading pollutants is added, and two glassy carbon electrodes (5) are inserted into the sealing plug (9) at the top and the side bottom of the threaded bottle (the distance between the two electrodes is controlled at 3-5 cm to prevent excessive electric field strength). (Unfavorable to microbial growth), connected to the positive and negative terminals of the electrochemical workstation 3 via wire 4 respectively. To record real-time current, the electrochemical workstation is connected to the laptop 1 via data cable 2. To simulate a redox oscillation environment, nitrogen cylinder 11 and air cylinder 12 are connected to the gas delivery pipe 6 respectively. The gas is introduced into the bottom of the threaded bottle 8 (below the liquid) through the through hole of the sealing plug 9. The gas flow rate is controlled by the flow meter 10. To ensure that the gas and solution are in full contact, the end of the gas delivery pipe 6 is connected to an aeration head 7 (the aeration head should be as large as possible to ensure that the solution is in full contact with the gas during the aeration process) for aeration.

[0033] Example 2

[0034] After drying, grinding, and sieving, the sludge is treated with synthetic glucose wastewater (6g C6H). 12 The reactor was activated for three months using a mixture of O6, 12g NaHCO3, 0.6g NH4Cl, 0.15g KH2PO4, and 2L H2O. 10g of the activated mixture was added to a sieve bottle (the apparatus in Example 1), along with 400ml of synthetic glucose wastewater. A voltage of 0.8V was applied to the experimental group, while no voltage was applied to the control group. Both reactors were incubated at 30℃ in a constant temperature incubator, and aeration with air and nitrogen was performed daily for 12 hours and 12 hours using a gas cylinder at a flow rate of 0.5L / h for three days.

[0035] The ferrous iron content in the supernatant of the electrically stimulated experimental group was consistently significantly higher than that of the control group, with the difference being more pronounced during the anaerobic phase. During the anaerobic phase on day three, the ferrous iron concentration in the supernatant of the electrically stimulated experimental group was 1.648 mg / L, 116.27% higher than the 0.762 mg / L in the control group; during the aerobic phase, the ferrous iron concentration in the supernatant of the electrically stimulated experimental group was 0.813 mg / L, 47.28% higher than the 0.552 mg / L in the control group.

[0036] Example 3

[0037] After drying, grinding, and sieving, the sludge was activated with synthetic glucose wastewater for three months. 10g of the sludge was added to a thread-sealed bottle (the apparatus in Example 1), along with 400ml of synthetic glucose wastewater. The experimental group was subjected to a voltage of 0.8V, while the control group was not subjected to a voltage. Both reactors were cultured in a 30℃ constant temperature incubator, and were aerated with air and nitrogen for 12 hours and 0.5L / h daily for three days.

[0038] The hydroxyl radical content in the electrical stimulation experimental group was consistently higher than that in the control group, especially during the anaerobic phase. On the third day of the anaerobic phase, the hydroxyl radical content in the electrical stimulation experimental group was 16.586 mg / L, 37.57% higher than the 12.056 mg / L in the control group; during the aerobic phase, the hydroxyl radical content in the electrical stimulation experimental group was 10.138 mg / L, 10.85% higher than the 9.146 mg / L in the control group.

[0039] Example 4

[0040] After drying, grinding, and sieving, the sludge was activated with synthetic glucose wastewater for three months. 10g of the sludge was added to a thread-sealed bottle (the apparatus in Example 1), along with 400ml of p-nitrophenol wastewater at a concentration of 80mg / L. The experimental group was subjected to a voltage of 0.8V, while the control group was not. Both reactors were cultured in a 30℃ constant-temperature incubator, and aerated with air for 12 hours and nitrogen for 12 hours daily via a gas cylinder at a flow rate of 0.5L / h for three days.

[0041] The concentration of p-nitrophenol in the experimental group was reduced to 8.11 mg / L, while the concentration in the control group was 25.79 mg / L, and the removal rate was 24.59% higher than that in the control group.

[0042] Example 5

[0043] After drying, grinding, and sieving, the sludge was activated with synthetic glucose wastewater for three months. 10g of the sludge was added to a thread-sealed bottle (the apparatus in Example 1), along with 400ml of p-nitrophenol wastewater at a concentration of 160mg / L. The experimental group was subjected to a voltage of 0.8V, while the control group was not. Both reactors were incubated in a 30℃ constant temperature incubator, and aerated with air for 12 hours and nitrogen for 12 hours daily via a gas cylinder at a flow rate of 0.5L / h for three days.

[0044] The concentration of p-nitrophenol in the experimental group was reduced to 18.37 mg / L, while the concentration in the control group was 54.18 mg / L, and the removal rate was 25.28% higher than that in the control group.

[0045] Example 6

[0046] After drying, grinding, and sieving, the sludge was activated with synthetic glucose wastewater for three months. 10g of the sludge was added to a sieve bottle (the apparatus in Example 1), along with 400ml of p-nitrophenol wastewater at a concentration of 200mg / L. The experimental group was subjected to a voltage of 0.8V, while the control group was not. Both reactors were incubated at 30℃ in a constant temperature incubator, and aerated with air for 12 hours and nitrogen for 12 hours daily via a gas cylinder at a flow rate of 0.5L / h for three days.

[0047] The concentration of p-nitrophenol in the experimental group was reduced to 55.33 mg / L, while the concentration in the control group was 106.04 mg / L, and the removal rate was 46.99% higher than that in the control group.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the advanced oxidative degradation of pollutants by microorganisms in a redox oscillatory region based on electrical stimulation, characterized in that, The method described herein is achieved through a device that accelerates the advanced oxidation and degradation of pollutants by microorganisms in a redox oscillatory region based on electrical stimulation. The device for accelerating the advanced oxidation and degradation of pollutants by microorganisms in an oxidation-reduction oscillating zone based on electrical stimulation includes a computer, a data cable, an electrochemical workstation, wires, electrodes, an air delivery tube, an aeration head, a threaded bottle, a sealing plug with three Φ6 through holes, a nitrogen cylinder, and an air cylinder. The threaded bottle has a water inlet at the bottom and an electrode insertion port on its side bottom. The threaded bottle and the sealing plug with three through holes are assembled into a reaction vessel. The positive and negative electrodes are inserted into the threaded bottle through the through holes of the sealing plug at the top and the electrode insertion port on the side bottom, respectively, and are connected to the positive and negative terminals of the electrochemical workstation via wires. The electrochemical workstation is connected to the computer via a data cable. The nitrogen cylinder and the air cylinder are connected to the air delivery tube, which extends into the bottom of the threaded bottle through the through holes of the sealing plug. An aeration head is connected to the end of each air delivery tube. The distance between the two electrodes is controlled at 3-5 cm to prevent excessive electric field strength from negatively impacting microbial growth. Includes the following steps: (1) After drying, grinding and screening, the sludge is activated for 2-4 months; (2) Add the activated sludge obtained in step (1) into a filament bottle, set a voltage of 0.5-1.0 V on the electrochemical workstation, generate an electric field through the electrodes connected by wires, electrically stimulate the electroactive microorganisms in the sludge, and record the current intensity in real time on the computer. (3) Control the flow of nitrogen or air into the nitrogen cylinder and air cylinder. Flow nitrogen for 12 hours and air for 12 hours every day until the pollutants are completely degraded and the reaction ends.

2. The method according to claim 1, characterized in that, Both nitrogen and air cylinders are equipped with flow meters to control the flow rate of the gas.

3. The method according to claim 1, characterized in that, The electrode is a glassy carbon electrode.

4. The method according to claim 1, characterized in that, The activation described in step (1) is performed using glucose wastewater.

5. The method according to claim 1, characterized in that, In step (2), the internal temperature of the swivel bottle is controlled at 28~30℃; the pH value inside the swivel bottle is controlled between 7.5 and 8.

5.

6. The method according to claim 1, characterized in that, In step (2), the hydraulic retention time of the swivel bottle is controlled between 5 and 7 days.

7. The method according to claim 1, characterized in that, In step (3), the gas flow rate is 0.5~1.5 L / h.

8. The application of the method for accelerating the advanced oxidation degradation of pollutants by microorganisms in redox oscillation zones based on electrical stimulation, as described in any one of claims 1-7, in wetland remediation.

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