Regulation and control method for biodegradability of petroleum hydrocarbon pollutants in soil

Abstract

The invention discloses a method for regulating and controlling biodegradability of petroleum hydrocarbon pollutants in soil, and belongs to the technical field of soil petroleum hydrocarbon pollution detection and governance. For the residual petroleum hydrocarbon pollutants which are difficult to degrade in the soil after microbial remediation, an active material is used as a cathode, an inert material is used as an anode, and the active material is used as an anode; the method comprises the following steps: by taking soil with residual refractory petroleum hydrocarbon pollutants as electrolyte, activating saturated hydrocarbon substances in the petroleum hydrocarbon pollutants through a cascade coupling effect of aerobic microorganisms and electrochemistry by adopting an electrochemical treatment mode under a constant voltage, and regulating and controlling the biodegradability of the petroleum hydrocarbon pollutants; therefore, the purpose of degrading residual petroleum hydrocarbon pollutants which are difficult to degrade in the soil is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of soil petroleum hydrocarbon pollutant treatment, and in particular to a method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil. Background Art

[0002] At present, the remediation technologies for petroleum hydrocarbon contaminated soil include physical, chemical and biological technologies. With the continuous progress of microbial remediation of petroleum pollution, the proportion of soil refractory petroleum hydrocarbon substances will continue to increase relatively, and nutrients will be scarce, resulting in a decrease in the biodegradability of petroleum hydrocarbon pollutants in the soil, the inactivation of the remediation bacteria, and a rapid decrease in degradation efficiency. In addition, the residual petroleum hydrocarbon pollutants contained in the petroleum hydrocarbon contaminated soil after microbial remediation are mostly macromolecular substances such as colloids and asphaltene. It is difficult to further degrade them by relying solely on the original petroleum pollution degradation microorganisms, and it is impossible to achieve the harmless requirement of less than 0.3% of petroleum hydrocarbon pollutants in the soil. There are a large number of aged petroleum hydrocarbon contaminated soils with low concentrations (≤2.5wt.%) in the oil well site, which poses a potential pollution to the surrounding environment. In addition, this type of petroleum hydrocarbon pollution often undergoes several years of natural degradation before remediation. In addition to the residual petroleum hydrocarbon pollutants after microbial degradation, the residual petroleum hydrocarbon pollution is also difficult to desorb due to the tight adsorption of petroleum hydrocarbons and soil fine particles due to the long-term weathering of the soil.

[0003] Low-concentration aged petroleum hydrocarbon contaminated soil and residual petroleum hydrocarbon pollutants after microbial remediation have common characteristics such as low oil content, high content of difficult-to-degrade petroleum hydrocarbon substances and poor bioaccessibility, which is one of the difficulties in microbial remediation of petroleum contaminated soil. At present, physical and chemical coupling microbial technology has effectively improved the efficiency of subsequent microbial remediation of soil, but in most studies, low-concentration petroleum hydrocarbon substances (oil content 1wt%~2wt%) are still residual in the soil after remediation, and the oil content cannot be reduced to a lower level (<0.3wt%), thereby achieving the effect of harmless soil remediation. If the existing coupled microbial treatment technology is still used, its degradation rate will decrease rapidly with the decrease in the concentration of petroleum hydrocarbon pollutants (≥30d), and the treatment is difficult. Summary of the invention

[0004] The present invention provides a method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil, which effectively solves the technical problems that when the existing physical and chemical coupling microbial technology is used to repair the soil, there are still residual low-concentration petroleum hydrocarbon substances, the oil content cannot be reduced to a lower level, and the soil cannot be efficiently and harmlessly repaired. The present invention uses a low-voltage electrochemical method to directly act on the difficult-to-degrade petroleum hydrocarbon pollutants remaining in the soil after microbial repair. While maintaining the physical and chemical properties of the soil and the soil environment, the saturated hydrocarbon substances in the petroleum hydrocarbon pollutants are activated by electrochemistry, the biodegradability of the saturated hydrocarbon substances in the residual petroleum hydrocarbons is improved, and the overall degradation efficiency of the petroleum hydrocarbon pollutants in the soil is improved, which greatly reduces the time required for subsequent microbial repair of the petroleum hydrocarbon pollutants.

[0005] The object of the present invention is to provide a method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil, comprising the following steps:

[0006] Using active materials as cathodes, inert materials as anodes, and residual soil with difficult-to-degrade petroleum hydrocarbon pollutants as electrolytes, electrochemical treatment is used under constant voltage. Through the cascade coupling of aerobic microorganisms and electrochemistry, saturated hydrocarbon substances in petroleum hydrocarbon pollutants are activated, the biodegradability of petroleum hydrocarbon pollutants is regulated, and the residual difficult-to-degrade petroleum hydrocarbon pollutants in the soil are degraded.

[0007] As a preferred implementation, the constant voltage is 6-18V.

[0008] As a preferred embodiment, the electrochemical treatment time is 1 to 4 days.

[0009] As a preferred embodiment, the aerobic microorganism is one or more of Pseudomonas, Bacillus, Acinetobacter, Proteus, Alcaligenes, Ochrobactrum, Sphingomonas and Micrococcus.

[0010] As a preferred embodiment, the concentration of the aerobic microbial suspension is 10 5 ~10 7 / mL; per cubic meter of soil, the amount of the bacterial suspension added is 0.3m 3 ~1.0m 3 .

[0011] As a preferred implementation, the distance between the anode and the cathode is 5 to 15 cm.

[0012] As a preferred embodiment, the electrode plate area of ​​the anode and cathode is 10 to 40 cm 2 The thickness of the anode electrode plate and the cathode electrode plate is 3 to 8 mm.

[0013] As a preferred embodiment, with the symmetry center between the anode electrode plate and the cathode electrode plate as the center of the circle, a group of anode electrode plates and cathode electrode plates treat the residual difficult-to-degrade petroleum hydrocarbon pollutants in spherical soil with a radius of 1 to 40 cm.

[0014] As a preferred implementation manner, the anode electrode plates and cathode electrode plates are arranged in multiple groups, and the distance between the symmetry centers of any two groups of anode electrode plates and cathode electrode plates is ≤60 cm.

[0015] As a preferred implementation, the cathode is a graphite electrode plate, and the anode is a platinum electrode plate or a titanium electrode plate.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides a method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil. Different from the traditional electrochemical soil remediation technology that directly oxidizes pollutants in the soil at the expense of the physical and chemical properties of the soil, or stimulates microorganisms in the soil by long-term electrical stimulation, the present invention targets the remaining difficult-to-degrade petroleum hydrocarbon pollutants in the soil after microbial remediation, uses active materials as cathodes, inert materials as anodes, and residual difficult-to-degrade petroleum hydrocarbon pollutants in the soil as electrolytes. The present invention uses electrochemical treatment at a constant voltage to activate saturated hydrocarbon substances in petroleum hydrocarbon pollutants through the step coupling of aerobic microorganisms and electrochemistry, and regulates the biodegradability of petroleum hydrocarbon pollutants, thereby achieving the purpose of degrading residual difficult-to-degrade petroleum hydrocarbon pollutants in the soil. The present invention optimizes the biodegradability of saturated hydrocarbon substances in residual difficult-to-degrade petroleum hydrocarbon substances through aerobic microorganisms and electrochemical methods, thereby achieving a method for regulating the overall biodegradability of residual petroleum hydrocarbon substances.

[0018] The invention has the characteristics of simple operation, low energy consumption and good treatment effect, and is conducive to the efficient implementation of aerobic microbial remediation of such residual refractory petroleum hydrocarbon-contaminated soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the electrochemical treatment device used in the method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil of the present invention.

[0020] Figure 2 This is a diagram showing the influence of plate area on the electrode action range and soil petroleum hydrocarbon degradation rate.

[0021] Figure 3This is the influence of plate thickness on degradation efficiency.

[0022] Figure 4 This is a diagram showing the effect of plate voltage on the biodegradability of residual petroleum hydrocarbons.

[0023] Figure 5 This is a diagram showing the effect of plate spacing on the biodegradability of residual petroleum hydrocarbons.

[0024] Figure 6 This is a diagram showing the effect of discharge time on the biodegradability of residual petroleum hydrocarbons.

[0025] Figure 7 Figure 1 is the change pattern of microbial enzyme activity in soil, where Figure a is the change graph of dehydrogenase activity, and Figure b is the change graph of catalase activity.

[0026] Figure 8 This is a diagram showing the electrochemical degradation of petroleum hydrocarbons in soil by microorganisms.

[0027] Fig. 9 This is a diagram showing the changes in the composition of petroleum hydrocarbons in soil during microbial degradation under optimal electrical parameters. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention. The following test methods and detection methods, unless otherwise specified, are conventional methods; the reagents and raw materials, unless otherwise specified, are commercially available.

[0029] In view of the above mentioned in the background technology of the present invention: First, with the continuous progress of microbial remediation of petroleum pollution, the proportion of soil refractory petroleum hydrocarbon substances will continue to increase relatively, and nutrients will be scarce, resulting in a decrease in the biodegradability of petroleum hydrocarbon pollutants in the soil, the inactivation of the remediation bacteria, and a rapid decrease in degradation efficiency. In addition, the residual petroleum hydrocarbon pollutants contained in the petroleum hydrocarbon contaminated soil after microbial remediation are mostly macromolecular substances such as colloids and asphaltene. It is difficult to further degrade them by relying solely on the original petroleum pollution degradation microorganisms, and it is impossible to achieve the harmless requirement of less than 0.3% of petroleum hydrocarbon pollutants in the soil. Second, in addition to the residual petroleum hydrocarbon pollutants after microbial degradation, the residual petroleum hydrocarbon pollution is also difficult to desorb due to the close adsorption of petroleum hydrocarbons and soil fine particles caused by long-term weathering of the soil. Third, the physical and chemical coupling microbial technology effectively improves the efficiency of subsequent microbial remediation of soil, but in most studies, there are still residual low-concentration petroleum hydrocarbon substances (oil content 1wt% to 2wt%) in the soil after remediation, and the oil content cannot be reduced to a lower level (<0.3wt%), thereby achieving the effect of harmless remediation of the soil. Based on the above technical problems, the present invention provides a method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil.

[0030] The technical solution of the present invention is described in detail below.

[0031] The present invention provides a method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil, comprising the following steps:

[0032] Using active materials as cathodes, inert materials as anodes, and residual soil with difficult-to-degrade petroleum hydrocarbon pollutants as electrolytes, electrochemical treatment is used under constant voltage. Through the cascade coupling of aerobic microorganisms and electrochemistry, saturated hydrocarbon substances in petroleum hydrocarbon pollutants are activated, the biodegradability of petroleum hydrocarbon pollutants is regulated, and the residual difficult-to-degrade petroleum hydrocarbon pollutants in the soil are degraded.

[0033] In the above technical solution, through the synergistic effect of electrochemistry and aerobic microorganisms, the difficult-to-degrade petroleum hydrocarbon pollutants in the soil are fully activated and effectively degraded.

[0034] It should be noted that the aerobic microorganisms used in the present invention are one or more of Pseudomonas, Acinetobacter, Proteus, Alcaligenes, Ochrobacter, Sphingomonas, Bacillus or Micrococcus. The concentration of the aerobic microorganism suspension is 10 5 ~10 7 / mL; per cubic meter of soil, the amount of the bacterial suspension added is 0.3m 3 ~1.0m 3 .

[0035] In order to improve the degradation efficiency, the constant voltage is 6 to 18V. Experiments show that when the voltage is lower than 6V, it cannot effectively affect petroleum hydrocarbons in the soil. The oil content of the soil after microbial remediation at a petroleum hydrocarbon contaminated soil remediation site was measured to be 1.6wt%. Under the condition that the discharge time (2d) and the plate spacing (10cm) remain unchanged, the plate voltage change (0, 6, 12, 18, 24V) is used as the basis for analyzing the biodegradability regulation ability of residual petroleum hydrocarbons in the soil. Figure 4 The figure shows the influence of plate voltage on the biodegradability of residual petroleum hydrocarbons. Figure 4 It can be seen that the effect of using microbial continuous degradation (control group) or electrochemical methods alone on petroleum hydrocarbons in the soil is limited. The degradation rate of petroleum hydrocarbons in the control group during the whole process is only 14%. When the voltage between the plates is 24V, the residual petroleum hydrocarbons in the soil before and after electrochemistry are only degraded by 15%. Figure 3It can be seen that the microorganisms have good petroleum hydrocarbon degradation efficiency for the soil after electrochemical treatment at any voltage of 6 to 24V, and as the voltage between the plates gradually increases, the subsequent microbial degradation rate of petroleum hydrocarbons in the soil increases accordingly, reaching the maximum value at a voltage of 18V. After that, the effect of further increasing the voltage on the microbial degradation efficiency becomes weaker, and the electrochemical degradation ability itself improves, indicating that excessive voltage causes the electrochemical biodegradability of petroleum hydrocarbons to be transformed into the ability to oxidize and decompose petroleum hydrocarbons. Therefore, combined with the above rules, the plate voltage from 6 to 18V can effectively improve the biodegradability of petroleum hydrocarbons in the soil, and the optimal plate voltage for the above soil samples is 18V.

[0036] In order to further improve the degradation rate of petroleum hydrocarbon pollutants, the power-on time is 1 to 4 days. Under the condition that the plate spacing (15 cm) and the plate voltage (18 V) remain unchanged, the subsequent changes in microbial degradation efficiency are used as the basis to analyze the ability of the discharge time change (1, 2, 3, 4, 5 days) to regulate the biodegradability of residual petroleum hydrocarbons in the soil. Figure 6 The discharge time changes the biodegradability of residual petroleum hydrocarbons in the soil. Figure 6 It can be seen that when the discharge time is less than 1d, the regulation effect and degradation effect are too low (less than 5%) and can be ignored. When the discharge time is ≥1d, as the discharge time is extended (from 1d to 4d), under the step-by-step coupling of microorganisms and electrochemistry, the degradation rate of petroleum hydrocarbons in the soil gradually increases, indicating that under the electrochemical action time of 1 to 4d, the present invention can obtain a good petroleum hydrocarbon degradation efficiency. In addition, as the action time is extended, the contribution of electrochemistry to the degradation of petroleum hydrocarbons in the soil also gradually increases, indicating that the electrochemical regulation effect on the biochemical properties of residual petroleum hydrocarbons will gradually transform into oxidative degradation. Therefore, the optimal discharge time in the present invention is 4d, when microbial degradation contributes the most to the degradation rate of petroleum hydrocarbons. This discharge time is the best for adjusting the biodegradability of residual petroleum hydrocarbons.

[0037] In order to further reduce the concentration of petroleum hydrocarbon pollutants in the soil, the distance between the anode electrode plate and the cathode electrode plate is 5 to 15 cm. Under the condition that the discharge time (2d) and the plate voltage (18V) remain unchanged, the change in the subsequent microbial degradation efficiency is used as the basis to analyze the biodegradability regulation ability of the plate spacing change (5, 10, 15, 20 cm) on the residual petroleum hydrocarbons in the soil. Figure 5 The curve of the change in the distance between the electrodes and the biodegradability of residual petroleum hydrocarbons in the soil is shown in Figure 2. Due to the conductive properties of the soil itself, arc breakdown and short circuit will occur when the distance between the electrode plates is less than 5 cm. Therefore, the relevant embodiments of the invention use 5 cm as the starting width of the distance between the electrodes. Figure 4It can be seen that under different electrode width conditions, electrochemistry can effectively improve the biodegradability of petroleum hydrocarbons in the soil. Compared with the control group, the microbial degradation efficiency is improved to varying degrees. As the electrode spacing increases, the efficiency of microbial degradation of petroleum hydrocarbons in the soil after electrochemistry increases accordingly. When the electrode spacing is 15 cm, the electrochemical degradation efficiency is relatively small, while the microbial degradation efficiency is the highest. When the electrode width reaches 20 cm, the microbial degradation efficiency begins to decline. Therefore, the method of the present invention uses an electrode width in the range of 5 to 15 cm to effectively improve the biodegradability of petroleum hydrocarbons in the soil, and a plate spacing of 15 cm is the optimal parameter for this time.

[0038] In order to ensure that a wider range of soil petroleum hydrocarbons can be electrochemically treated and biodegradability is improved, the area of ​​the anode electrode plate and the cathode electrode plate is 20 to 30 cm 2 .like Figure 2 As shown in the figure, under different inter-plate voltage conditions, the plate area has a significant effect on the action radius of the device of the present invention and the degradation rate of soil petroleum hydrocarbons. 2 When the plate area continues to increase, the degradation efficiency and the effective radius begin to decrease due to excessive power reduction per unit area. Therefore, the plate area is 20 to 30 cm 2 A higher degradation rate can be obtained when the effective radius is 30-40 cm, and 20 cm 2 The optimum plate area is .

[0039] In order to ensure the strength and degradation efficiency of the electrode plate, the thickness of the electrode plate is 3 to 8 mm. The soil was taken from a petroleum hydrocarbon contaminated soil remediation site and the oil content was 1.6 wt % after microbial remediation. Under the condition that the discharge time (2d), the electrode plate spacing (10cm), the electrode plate area (20cm) and the discharge voltage (18) remain unchanged, the subsequent microbial degradation efficiency change is used as the basis to analyze the change of the electrode plate thickness (3, 6, 9, 12mm. Due to strength reasons, the electrode plate thickness cannot be less than 3mm. Figure 3 The figure shows the influence of different thickness plates on the degradation efficiency of residual petroleum in soil. It can be seen from the figure that within a certain thickness range (3-8mm), the petroleum hydrocarbon shows a significant decrease when it reaches 8mm. Therefore, based on cost and strength considerations, the thickness of the electrode plate can be selected within 3-8mm, and 3mm is the optimal thickness.

[0040] As a preferred embodiment, with the symmetry center between the anode electrode plate and the cathode electrode plate as the center of the circle, a group of anode electrode plates and cathode electrode plates treat the residual difficult-to-degrade petroleum hydrocarbon pollutants in spherical soil with a radius of 40 to 50 cm.

[0041] In order to degrade a wider range of petroleum hydrocarbon pollutants, the anode electrode plates and cathode electrode plates are arranged in multiple groups, and the distance between the symmetry centers of any two groups of anode electrode plates and cathode electrode plates is ≤60cm, thereby ensuring that the action ranges of different groups of electrode plates overlap and cause energy waste.

[0042] As a preferred embodiment, the anode electrode plate and the cathode electrode plate are graphite electrode plates, platinum electrodes or titanium metal electrodes. Due to cost reasons, graphite electrode plates are the best choice.

[0043] The technical effects of the present invention are described below in conjunction with embodiments and comparative examples.

[0044] like Figure 1 As shown, the device for regulating the biodegradability of petroleum hydrocarbon pollutants in soil used in the method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil of the present invention mainly comprises a DC power supply, a conductor and a graphite plate. When the soil area is large, the device can be arranged in series at a certain distance.

[0045] Example 1

[0046] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0047] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0048] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 6V and the degradation treatment is carried out for 4 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0049] Example 2

[0050] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0051] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2, the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0052] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 12V and the degradation treatment is carried out for 4 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0053] Example 3

[0054] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0055] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0056] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 4 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0057] Example 4

[0058] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0059] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas and Bacillus suspensions was added to the soil using a meter. Then, a 30 cm2 meter was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0060] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 6V and the degradation treatment is carried out for 4 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0061] Example 5

[0062] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0063] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas and Bacillus suspensions was added to the soil using a meter. Then, a 30 cm2 meter was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0064] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 12V and the degradation treatment is carried out for 4 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0065] Example 6

[0066] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0067] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas and Bacillus suspensions was added to the soil using a meter. Then, a 30 cm2 meter was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0068] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 4 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0069] Example 7

[0070] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0071] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2, the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 10cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0072] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0073] Example 8

[0074] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0075] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 6mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 10cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0076] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0077] Example 9

[0078] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0079] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 8mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 10cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0080] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0081] Example 10

[0082] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0083] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 10cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0084] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 6V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0085] Embodiment 11

[0086] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0087] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 10cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0088] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 12V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0089] Example 12

[0090] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0091] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2, the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 10cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0092] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0093] Embodiment 13

[0094] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0095] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 5cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0096] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0097] Embodiment 14

[0098] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0099] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0100] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 2 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0101] Embodiment 15

[0102] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0103] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0104] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 1 day to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0105] Example 16

[0106] A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil comprises the following steps:

[0107] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0108] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 3 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0109] Embodiment 17

[0110] A method for biodegrading petroleum hydrocarbon pollutants in soil comprises the following steps:

[0111] In the soil with residual refractory petroleum hydrocarbon contamination of 1.6wt% oil content, 0.3m3 of 3 The mixed bacterial solution of Pseudomonas suspension and Bacillus suspension was added to the soil, and then a 20cm2 micrometer was inserted into the soil. 2, the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0112] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 18V and the degradation treatment is carried out for 4 days to obtain the soil after the petroleum hydrocarbon pollutants are degraded.

[0113] In order to further illustrate the technical effect of the present invention, the present invention also sets a comparative example, which is as follows:

[0114] Comparative Example 1 (control group)

[0115] Only microbial degradation was used, specifically: a bacterial suspension of Pseudomonas and a bacterial suspension of Bacillus were mixed to obtain a mixed bacterial solution, wherein the concentration of Pseudomonas was 3×10 5 The concentration of Bacillus was 2.8×10 5 , the mixed bacterial solution was added at 0.3m3 per cubic meter of soil 3 Add the volume amount to the soil.

[0116] Comparative Example 2

[0117] Only electrochemical treatment is used.

[0118] In soils with residual refractory petroleum hydrocarbon contaminants, the insertion area is 20 cm 2 , the anode electrode plate and the cathode electrode plate are 3mm thick, and the distance between the anode electrode plate and the cathode electrode plate is controlled to be 15cm. In order to ensure the consistency of the medium and uniform resistance between the plates, all the plates should be inserted into the soil layer.

[0119] The anode electrode plate and the cathode electrode plate are connected to the positive electrode and the negative electrode of the power supply respectively. After power is turned on, the voltage is adjusted to 6V and the degradation treatment is performed for 4 days.

[0120] The above embodiments of the present invention are used to degrade the soil contaminated by petroleum hydrocarbons. The degradation effect of petroleum hydrocarbons in the soil of each embodiment is good. Among them, the degradation effect of embodiment 3 is the best. The optimal electrochemical parameters obtained in embodiment 3 (electrode plate spacing 15cm, electrode plate thickness 3mm, electrode plate area 20cm 2 Under the conditions of 18V, plate voltage 18V, and electrochemical time 4d, the changes in biological activity during direct microbial degradation and electrochemical degradation were investigated. Dehydrogenase activity and catalase activity are the main functional enzymes in the process of microbial degradation of petroleum hydrocarbons. The activities of these two enzymes directly reflect the activity of the microbial degradation process. Figure 7It can be seen that compared with the blank group that was directly treated with microorganisms without electrochemical treatment, the activities of the two enzymes in the soil after electrochemical adjustment of biodegradability were significantly higher than those in the blank group as microbial degradation proceeded. This phenomenon proves that electrochemistry has an improving effect on the biological activity of difficult-to-degrade residual petroleum hydrocarbons in the soil.

[0121] The composition of residual petroleum hydrocarbons in the soil after electrochemical and subsequent microbial treatment in Examples 12, 14 and 16 was analyzed by gas chromatography-mass spectrometry (GC-MS). Figure 8 and Fig. 9 .

[0122] Among them, the control group was only subjected to microbial degradation, group A was only subjected to electrochemical treatment, group A+B was when the voltage was 18V in Example 12, group A+B+C was when the plate spacing was 15cm in Example 14, and group A+B+C+D was when the discharge time was 4d in Example 16.

[0123] from Figure 8 It can be seen that after the stepwise optimization of parameters in Example 12, Example 14 and Example 16, the electrochemical adjustment effect on the biodegradability of residual petroleum hydrocarbons in the soil is gradually strengthened, corresponding to Figures 4 to 6 The best microbial degradation efficiency shown in each figure gradually increases. The changes in petroleum hydrocarbon components in the samples corresponding to the best microbial degradation efficiency in the above figures are as follows: Figure 8 As shown, the concentration of saturated hydrocarbons changed little before and after electrochemical treatment (control group and group A), but with the progress of parameter optimization, the saturated hydrocarbons in the petroleum hydrocarbons of group A+B corresponding to Example 12, group A+B+C corresponding to Example 14, and group A+B+C+D corresponding to Example 16 decreased after microbial degradation, and the concentration gradually decreased, indicating that electrochemistry has a good effect on adjusting the biodegradability of saturated hydrocarbons in petroleum hydrocarbons, resulting in the efficiency of saturated hydrocarbons being degraded by microorganisms gradually increasing with the optimization of electrochemical parameters, which also led to a gradual decrease in the concentration of saturated hydrocarbons. Fig. 9 The overall peak concentration of saturated hydrocarbons can also be seen to decrease significantly as the electrochemical parameters are optimized.

[0124] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for regulating the biodegradability of petroleum hydrocarbon pollutants in soil, characterized in that: The following steps are involved: Using active materials as cathodes, inert materials as anodes, and residual soil with difficult-to-degrade petroleum hydrocarbon pollutants as electrolytes, electrochemical treatment is used under constant voltage. Through the cascade coupling of aerobic microorganisms and electrochemistry, saturated hydrocarbon substances in petroleum hydrocarbon pollutants are activated, the biodegradability of petroleum hydrocarbon pollutants is regulated, and the residual difficult-to-degrade petroleum hydrocarbon pollutants in the soil are degraded.

2. The control method according to claim 1, characterized in that: The constant voltage is 6-18V.

3. The control method according to claim 1, characterized in that: The electrochemical treatment time is 1 to 4 days.

4. The control method according to claim 1, characterized in that: The aerobic microorganisms are one or more of Pseudomonas, Acinetobacter, Proteus, Alcaligenes, Ochrobacter, Sphingomonas, Bacillus or Micrococcus.

5. The control method according to claim 4, characterized in that: The concentration of the aerobic microbial suspension is 10 5 ~10 7 / mL; per cubic meter of soil, the amount of the bacterial suspension added is 0.3m 3 ~1.0m 3 .

6. The control method according to claim 1, characterized in that: The distance between the anode and the cathode is 5 to 15 cm.

7. The control method according to claim 6, characterized in that: The electrode plates of the anode and cathode have an area of ​​10 to 40 cm 2 The thickness of the anode electrode plate and the cathode electrode plate is 3 to 8 mm.

8. The control method according to claim 7, characterized in that: With the symmetry center between the anode electrode plate and the cathode electrode plate as the center of the circle, a group of anode electrode plates and cathode electrode plates treat the residual difficult-to-degrade petroleum hydrocarbon pollutants in spherical soil with a radius of 1 to 40 cm.

9. The control method according to claim 7, characterized in that: The anode electrode plates and cathode electrode plates are arranged in multiple groups, and the distance between the symmetry centers of any two groups of anode electrode plates and cathode electrode plates is ≤60 cm.

10. The control method according to claim 1, characterized in that: The cathode is a graphite electrode plate, and the anode is a platinum electrode plate or a titanium electrode plate.

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