Online monitoring equipment and method for petroleum hydrocarbon pollution in aeration zone soil

Abstract

The invention discloses online monitoring equipment and method for petroleum hydrocarbon pollution in aeration zone soil. An opening is formed in the upper portion of a shell, and a plurality of screen holes are evenly formed in the shell. The biochar inner cylinder is coaxially arranged in the shell, and the outer circumference of the biochar inner cylinder is matched with the inner circumference of the shell; the steel screen is arranged in the center of the biological carbon inner cylinder; the mixed soil is filled in an annular space between the biochar inner cylinder and the steel screen and in the steel screen; a negative electrode and a positive electrode of the voltage monitor are electrically connected with the biological carbon inner cylinder and the steel screen respectively; the mixed soil is formed by mixing an electricity-producing bacterium agent and clean soil, the addition amount of the electricity-producing bacterium agent in the mixed soil is 3-8%, the microorganism concentration of the electricity-producing bacterium agent is 107-109 per mL, and the electricity-producing bacterium is a petroleum hydrocarbon degrading flora. The device has the advantage that the petroleum hydrocarbon pollution degree can be reflected through electric signals.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental pollutant monitoring, and particularly relates to an on-line monitoring device and method for petroleum hydrocarbon pollution in vadose zone soil. Background Art

[0002] Petroleum hydrocarbon pollutants are typical characteristic pollutants of oil and petrochemical enterprises during production. During the processes of enterprise production, transportation, use, etc., phenomena such as running, dripping, and leaking inevitably occur, causing petroleum hydrocarbon pollution in vadose zone soil. Soil pollution generally has a certain degree of concealment. Some petroleum hydrocarbons can also exist in gaseous form in the vadose zone. When pollution occurs, it is often not discovered in time, resulting in further aggravation and spread of the pollution. Some gaseous petroleum hydrocarbons are easily migrated into the atmosphere, posing a certain risk to human health through the respiratory pathway, and even affecting the normal production of enterprises. Therefore, it is particularly necessary to timely understand the soil petroleum hydrocarbon pollution situation.

[0003] Currently, commonly used drilling sampling methods and geophysical methods are available. The drilling sampling method has certain limitations. First, it is easy to form a pollutant migration channel. Geological drilling or penetration detection will damage the distribution and enrichment structure of pollutants underground, and may cause pollutants to continue to migrate deeper along the drill hole. Second, the cycle is long and the real-time performance is poor. After obtaining samples on site, processes such as sample transportation, pretreatment, and laboratory monitoring are required, and the cycle for obtaining data is relatively long. Third, the cost is relatively high. In the whole process, mechanical equipment costs, laboratory analysis and testing costs, etc. need to be considered. Although the geophysical method can well overcome the above problems and has characteristics such as spatial comprehensiveness, in-situ non-destruction, and high speed, this method is easily interfered by site equipment, facilities, and structures and is limited by the site, with a limited detection depth and high requirements for on-site technical personnel. Both have certain limitations in terms of timeliness, accuracy, etc.

[0004] In order to timely and accurately understand the pollution situation, it is necessary to apply fast and efficient soil environmental monitoring methods. Existing invention patents for biological monitoring of polluted soil use soil organisms such as earthworms as indicator organisms, and monitor the soil pollution situation by analyzing oxidative damage in their bodies and analyzing the response of soil ecosystems to pollutants. Existing such polluted soil monitoring methods have many influencing factors, the analysis process is cumbersome, and data cannot be directly read, which is not conducive to practical application.

[0005] The present invention utilizes microbial electrochemical technology to monitor the voltage change generated by the release of electrons during the degradation of petroleum hydrocarbons by electrogenic bacteria in the test area, and reflects the petroleum hydrocarbon pollution situation in this area, which can be used as a warning signal for the pollution of petroleum hydrocarbon substances in the site. Summary of the Invention

[0006] The purpose of the present invention is to provide an on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil, which is provided with a housing, a biochar inner cylinder, a steel screen, mixed soil and a voltage monitor. The electricity-producing bacteria in the mixed soil come into contact with pollutants, grow and reproduce by using organic matter to generate electricity, and thus the degree of petroleum hydrocarbon pollution can be reflected through electrical signals.

[0007] Another purpose of the present invention is to provide an on-line monitoring method for petroleum hydrocarbon pollution in vadose zone soil. The electricity-producing bacteria in the mixed soil come into contact with pollutants, grow and reproduce by using organic matter to generate electricity, and thus the degree of petroleum hydrocarbon pollution can be reflected through electrical signals.

[0008] To achieve the above purposes, the present invention adopts the following technical solutions, including:

[0009] A housing, which is provided with an opening at its upper part, and a plurality of sieve holes are evenly arranged on the housing;

[0010] A biochar inner cylinder, which is coaxially arranged inside the housing, and the outer periphery of the biochar inner cylinder is adapted to the inner periphery of the housing;

[0011] A steel screen, which is arranged at the center of the biochar inner cylinder;

[0012] Mixed soil, which is filled in the annulus between the biochar inner cylinder and the steel screen and inside the steel screen;

[0013] A voltage monitor, whose negative electrode and positive electrode are electrically connected to the biochar inner cylinder and the steel screen respectively;

[0014] Among them, the mixed soil is composed of an electricity-producing bacteria agent and clean soil, and the addition amount of the electricity-producing bacteria agent in the mixed soil is 3-8%, the microbial concentration of the electricity-producing bacteria agent is 10 7 -10 9 CFU / mL, and the electricity-producing bacteria are petroleum hydrocarbon degrading flora.

[0015] Preferably, a drill bit is provided below the housing.

[0016] Preferably, a detachable upper cover is provided at the opening of the housing.

[0017] Preferably, the inner diameter of the housing is 4-6 cm, the depth is 8-10 cm, the thickness is 0.2-0.5 cm, and the sieve holes are 10-50 meshes; the outer diameter of the biochar inner cylinder is 4-6 cm, the height is 8-10 cm, and the thickness is 1-2 cm; the outer diameter of the steel screen is 1-2 cm, the height is 8-10 cm, the thickness is 0.2-0.5 cm, and the sieve mesh is 10-50 meshes; the radius of the upper cover is 4-6 cm, and the thickness is 0.2-0.5 cm.

[0018] Preferably, the inner diameter of the housing is 5 cm, the depth is 9 cm, the thickness is 0.25 cm, and the sieve holes are 20 mesh; the outer diameter of the inner cylinder of biochar is 5 cm, the height is 9 cm, and the thickness is 1.5 cm; the outer diameter of the steel screen is 1.5 cm, the height is 9 cm, the thickness is 0.25 cm, and the sieve mesh is 20 mesh; the radius of the upper cover is 5 cm, and the thickness is 0.25 cm.

[0019] Preferably, the addition amount of the electrogenic bacteria agent in the mixed soil is 5%, and the microbial concentration of the electrogenic bacteria agent is 10 8 cells / mL.

[0020] An on-line monitoring method for petroleum hydrocarbon pollution in vadose zone soil, which applies the on-line monitoring equipment for petroleum hydrocarbon pollution in vadose zone soil described in any one of the above, is characterized by including the following steps:

[0021] S1. Add the electrogenic bacteria agent into the clean soil according to the addition amount of 3-8% to make mixed soil, and then fill the annulus between the inner cylinder of biochar and the steel screen and inside the steel screen with the mixed soil; wherein, the microbial concentration of the electrogenic bacteria agent is 10 7 -10 9 cells / mL, and the electrogenic bacteria are petroleum hydrocarbon degradation flora;

[0022] S2. Conduct starvation pretreatment on the on-line monitoring equipment for petroleum hydrocarbon pollution in vadose zone soil.

[0023] S3. Take 6 portions of clean soil, and then add petroleum hydrocarbons to each portion of clean soil respectively. After stirring evenly, prepare 6 portions of standard soil. The petroleum hydrocarbon concentration in each portion of standard soil is 100 mg / kg, 200 mg / kg, 300 mg / kg, 400 mg / kg, 500 mg / kg, 600 mg / kg; then place the 6 portions of standard soil in 6 containers with open upper ends to simulate the formation environment and prevent water evaporation; then take 6 on-line monitoring equipment for petroleum hydrocarbon pollution in vadose zone soil after starvation pretreatment, and bury them one by one in the 6 containers filled with standard soil, and keep them at the same temperature as the soil to be measured. Pay attention to the voltage change. When the voltage reaches the peak value, record the maximum voltage value, make a standard curve of maximum voltage - petroleum hydrocarbon concentration, and obtain the fitting equation as:

[0024] y = 0.409x + 13.46, R 2 = 0.95 (1)

[0025] In formula (1): y is the maximum voltage, mv; x is the petroleum hydrocarbon concentration, mg / kg;

[0026] S4. Take another on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil after starvation pretreatment, place it in the formation to be measured, record the maximum voltage value, and obtain the pollution degree of petroleum hydrocarbon in the formation according to the fitting equation.

[0027] Preferably, in step S2, the method of starvation pretreatment is as follows: electrically connect the negative electrode and the positive electrode of the voltage monitor to the inner biochar cylinder and the steel screen respectively, and bury the on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil in clean soil until the voltage is stable.

[0028] The beneficial effect of the present invention is that it can reflect the pollution degree of petroleum hydrocarbon through electrical signals. Description of the Drawings

[0029] Figure 1 It is a cross-sectional view of an on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil of the present invention.

[0030] Figure 2 It is a schematic diagram of the standard curve of maximum voltage - petroleum hydrocarbon concentration in the present invention. Detailed Embodiments

[0031] The following further describes the invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0032] It should be understood that the terms such as "having", "comprising" and "including" used herein do not exclude the existence or addition of one or other elements or their combinations.

[0033] Embodiment 1

[0034] As Figure 1 shown, an on-line monitoring device 1 for petroleum hydrocarbon pollution in vadose zone soil of the present invention includes:

[0035] A housing 110 with an opening at its upper part, and a plurality of screen holes 111 are evenly arranged on the housing; a drill bit 160 is provided below the housing 110. A detachable upper cover 170 is provided at the opening of the housing 110. A biochar inner cylinder 120 is coaxially arranged inside the housing 110, and the outer periphery of the biochar inner cylinder 120 is adapted to the inner periphery of the housing 110; a steel screen 130 is arranged at the center of the biochar inner cylinder 120; a mixed soil 140 is filled in the annulus between the biochar inner cylinder 120 and the steel screen 130 and inside the steel screen 130; a voltage monitor 150, whose negative electrode and positive electrode are electrically connected to the biochar inner cylinder 120 and the steel screen 130 respectively;

[0036] Among them, the mixed soil 140 is formed by mixing an electricity-producing bacteria agent and clean soil. The addition amount of the electricity-producing bacteria agent in the mixed soil is 5%, and the microbial concentration of the electricity-producing bacteria agent is 10 8 CFU / mL. The electricity-producing bacteria are a petroleum hydrocarbon-degrading bacterial community, and the clean soil refers to soil with a petroleum hydrocarbon content of 0 - 0.04 mg / kg. The inner diameter of the shell is 5 cm, the depth is 9 cm, the thickness is 0.25 cm, and the sieve holes are 20 mesh; the outer diameter of the biochar inner cylinder is 5 cm, the height is 9 cm, and the thickness is 1.5 cm; the outer diameter of the steel screen is 1.5 cm, the height is 9 cm, the thickness is 0.25 cm, and the sieve mesh is 20 mesh; the radius of the upper cover is 5 cm, and the thickness is 0.25 cm.

[0037] An on-line monitoring method for petroleum hydrocarbon pollution in vadose zone soil, applying the on-line monitoring equipment for petroleum hydrocarbon pollution in vadose zone soil described in any one of the above, is characterized by including the following steps:

[0038] S1. Add the electricity-producing bacteria agent into the clean soil according to the addition amount of 5% to make mixed soil, and then fill the annulus between the biochar inner cylinder 120 and the steel screen 130 and inside the steel screen 130 with the mixed soil; among them, the microbial concentration of the electricity-producing bacteria agent is 10 8 CFU / mL, and the electricity-producing bacteria are a petroleum hydrocarbon-degrading bacterial community;

[0039] S2. Conduct starvation pretreatment on the on-line monitoring equipment 1 for petroleum hydrocarbon pollution in vadose zone soil; the method of starvation pretreatment is: electrically connect the negative electrode and the positive electrode of the voltage monitor 150 to the biochar inner cylinder 120 and the steel screen 130 respectively, and bury the on-line monitoring equipment 1 for petroleum hydrocarbon pollution in vadose zone soil in the clean soil until the voltage is stable;

[0040] S3. Take 6 portions of clean soil, and then add petroleum hydrocarbons to each portion of clean soil respectively. After stirring evenly, prepare 6 portions of standard soil. The petroleum hydrocarbon concentration in each portion of standard soil is 100 mg / kg, 200 mg / kg, 300 mg / kg, 400 mg / kg, 500 mg / kg, 600 mg / kg; then place the 6 portions of standard soil in 6 containers with open tops respectively to simulate the formation environment and prevent water evaporation; then take 6 on-line monitoring equipment for petroleum hydrocarbon pollution in vadose zone soil after starvation pretreatment, and bury them one by one in the 6 containers filled with standard soil respectively, and keep them at the same temperature as the soil to be measured. Pay attention to the voltage change. When the voltage reaches the peak value, record the maximum voltage value, and make a standard curve of maximum voltage - petroleum hydrocarbon concentration, as Figure 2 shown in, and obtain the fitting equation as:

[0041] y = 0.409x + 13.46, R2 = 0.95 (1)

[0042] In formula (1): y is the maximum voltage, in mV; x is the concentration of petroleum hydrocarbons, in mg / kg;

[0043] S4. Then take another on-line monitoring device 1 for petroleum hydrocarbon pollution in the vadose zone soil after starvation pretreatment, place it into the formation to be measured respectively, record the maximum voltage y1 = 36 mV, and obtain the pollution degree of petroleum hydrocarbons in the formation to be 55.1 mg / kg according to the fitting equation.

[0044] Example 2

[0045] As Figure 1 shown, an on-line monitoring device 1 for petroleum hydrocarbon pollution in vadose zone soil of the present invention includes:

[0046] A housing 110 with an opening at its upper part, and a plurality of sieve holes 111 are evenly arranged on the housing; a drill bit 160 is provided below the housing 110. A detachable upper cover 170 is provided at the opening of the housing 110. A biochar inner cylinder 120 is coaxially arranged inside the housing 110, and the outer circumference of the biochar inner cylinder 120 is adapted to the inner circumference of the housing 110; a steel mesh 130 is arranged at the center of the biochar inner cylinder 120; a mixed soil 140 is filled in the annulus between the biochar inner cylinder 120 and the steel mesh 130 and inside the steel mesh 130; a voltage monitor 150, whose negative electrode and positive electrode are electrically connected to the biochar inner cylinder 120 and the steel mesh 130 respectively;

[0047] Among them, the mixed soil 140 is composed of an electrogenic bacteria agent and clean soil, and the addition amount of the electrogenic bacteria agent in the mixed soil is 8%, and the microbial concentration of the electrogenic bacteria agent is 10 7 cells / mL, the electrogenic bacteria are petroleum hydrocarbon degrading bacteria groups, and the clean soil refers to the soil with the content of petroleum hydrocarbons being 0 - 0.04 mg / kg. The inner diameter of the housing 110 is 4 cm, the depth is 10 cm, the thickness is 0.2 cm, and the sieve holes are 50 meshes; the outer diameter of the biochar inner cylinder is 4 cm, the height is 10 cm, and the thickness is 1 cm; the outer diameter of the steel mesh is 2 cm, the height is 8 cm, the thickness is 0.5 cm, and the sieve mesh is 10 meshes; the radius of the upper cover is 6 cm, and the thickness is 0.2 cm.

[0048] An on-line monitoring method for petroleum hydrocarbon pollution in vadose zone soil, applying the on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil described in any one of the above, is characterized by including the following steps:

[0049] S1. Add the electrogenic bacteria agent to the clean soil at an addition rate of 8% to make a mixed soil, and then fill the annulus between the biochar inner cylinder 120 and the steel screen 130 and inside the steel screen 130 with the mixed soil; wherein, the microbial concentration of the electrogenic bacteria agent is 10 7 CFU / mL, and the electrogenic bacteria are petroleum hydrocarbon-degrading bacterial communities;

[0050] S2. Conduct starvation pretreatment on the on-line monitoring device 1 for petroleum hydrocarbon pollution in the vadose zone soil; the method of starvation pretreatment is: electrically connect the negative and positive electrodes of the voltage monitor 150 to the biochar inner cylinder 120 and the steel screen 130 respectively, and bury the on-line monitoring device 1 for petroleum hydrocarbon pollution in the vadose zone soil in the clean soil until the voltage is stable;

[0051] S3. Take 6 portions of clean soil, and then add petroleum hydrocarbons to each portion of clean soil respectively. After stirring evenly, prepare 6 portions of standard soil. The petroleum hydrocarbon concentrations in each portion of standard soil are 100 mg / kg, 200 mg / kg, 300 mg / kg, 400 mg / kg, 500 mg / kg, and 600 mg / kg; then place the 6 portions of standard soil in 6 containers with open tops respectively to simulate the formation environment and prevent water evaporation; then take 6 on-line monitoring devices 1 for petroleum hydrocarbon pollution in the vadose zone soil after starvation pretreatment, bury them one by one in the 6 containers filled with standard soil respectively, and keep them at the same temperature as the soil to be measured. Pay attention to the voltage change. When the voltage reaches the peak value, record the maximum voltage value, and make a standard curve of maximum voltage - petroleum hydrocarbon concentration, such as Figure 2 and obtain the fitting equation as:

[0052] y = 0.409x + 13.46, R 2 = 0.95 (1)

[0053] In formula (1): y is the maximum voltage, mV; x is the petroleum hydrocarbon concentration, mg / kg;

[0054] S4. Take another on-line monitoring device 1 for petroleum hydrocarbon pollution in the vadose zone soil after starvation pretreatment, place it in the formation to be measured respectively, record the maximum voltage value y2 = 124 mV, and obtain the pollution degree of petroleum hydrocarbons in the formation to be measured as 270.3 mg / kg according to the fitting equation.

[0055] Example 3

[0056] As Figure 1 shown, an on-line monitoring device 1 for petroleum hydrocarbon pollution in the vadose zone soil of the present invention includes:

[0057] A housing 110, which has an opening above it, and is provided with a plurality of sieve holes 111 evenly distributed on the housing; a drill bit 160 is provided below the housing 110. A detachable upper cover 170 is provided at the opening of the housing 110. A biochar inner cylinder 120, which is coaxially arranged inside the housing 110, and the outer circumference of the biochar inner cylinder 120 is adapted to the inner circumference of the housing 110; a steel sieve 130, which is arranged at the center of the biochar inner cylinder 120; a mixed soil 140, which is filled in the annulus between the biochar inner cylinder 120 and the steel sieve 130 and inside the steel sieve 130; a voltage monitor 150, whose negative electrode and positive electrode are electrically connected to the biochar inner cylinder 120 and the steel sieve 130 respectively;

[0058] Among them, the mixed soil 140 is composed of an electricity-producing bacterium agent and clean soil, and the addition amount of the electricity-producing bacterium agent in the mixed soil is 3%, and the microbial concentration of the electricity-producing bacterium agent is 10 9 cells / mL, the electricity-producing bacterium is a petroleum hydrocarbon-degrading bacterial community, and the clean soil refers to the soil with the petroleum hydrocarbon content of 0 - 0.04 mg / kg.

[0059] The inner diameter of the housing 110 is 6 cm, the depth is 8 cm, the thickness is 0.5 cm, and the sieve holes are 10 mesh; the outer diameter of the biochar inner cylinder is 6 cm, the height is 8 cm, and the thickness is 2 cm; the outer diameter of the steel sieve is 1 cm, the height is 10 cm, the thickness is 0.2 cm, and the sieve is 50 mesh; the radius of the upper cover is 4 cm and the thickness is 0.5 cm.

[0060] An on-line monitoring method for petroleum hydrocarbon pollution in vadose zone soil, which applies the on-line monitoring device 1 for petroleum hydrocarbon pollution in vadose zone soil described in any one of the above, is characterized by including the following steps:

[0061] S1. Add the electricity-producing bacterium agent into the clean soil at an addition amount of 3% to make a mixed soil, and then fill the annulus between the biochar inner cylinder 120 and the steel sieve 130 and inside the steel sieve 130 with the mixed soil; among them, the microbial concentration of the electricity-producing bacterium agent is 10 9 cells / mL, and the electricity-producing bacterium is a petroleum hydrocarbon-degrading bacterial community;

[0062] S2. Perform starvation pretreatment on the on-line monitoring device 1 for petroleum hydrocarbon pollution in vadose zone soil; the method of the starvation pretreatment is: electrically connect the negative electrode and the positive electrode of the voltage monitor 150 to the biochar inner cylinder 120 and the steel sieve 130 respectively, and bury the on-line monitoring device 1 for petroleum hydrocarbon pollution in vadose zone soil in the clean soil until the voltage is stable;

[0063] S3. Take 6 portions of clean soil, and then add petroleum hydrocarbons to each portion of the clean soil respectively. After stirring evenly, prepare 6 portions of standard soil. The petroleum hydrocarbon concentrations in each portion of the standard soil are 100 mg / kg, 200 mg / kg, 300 mg / kg, 400 mg / kg, 500 mg / kg, and 600 mg / kg. Then place the 6 portions of the standard soil in 6 containers with open tops respectively to simulate the formation environment and prevent water evaporation. Then take 6 on-line monitoring devices for petroleum hydrocarbon pollution in the vadose zone soil after starvation pretreatment, and bury them one by one in the 6 containers filled with the standard soil respectively, and keep them at the same temperature as the soil to be measured. Pay attention to the voltage change. When the voltage reaches the peak value, record the maximum voltage value, and make a standard curve of the maximum voltage - petroleum hydrocarbon concentration, as Figure 2 , and obtain the fitting equation as:

[0064] y = 0.409x + 13.46, R 2 = 0.95 (1)

[0065] In formula (1): y is the maximum voltage, mv; x is the petroleum hydrocarbon concentration, mg / kg;

[0066] S4. Take another on-line monitoring device 1 for petroleum hydrocarbon pollution in the vadose zone soil after starvation pretreatment, and place it in the formation to be measured respectively. Record the maximum voltage value y3 = 223 mv, and obtain the pollution degree of petroleum hydrocarbons in the formation to be 512.3 mg / kg according to the fitting equation.

[0067] In summary, an on-line monitoring device and method 1 for petroleum hydrocarbon pollution in the vadose zone soil of the present invention can reflect the pollution degree of petroleum hydrocarbons through electrical signals.

[0068] Although the embodiments of the present invention have been disclosed as above, it is not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated and described examples here.

Claims

1. An on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil, characterized in that, Comprising: A housing having an opening at its upper part, and a plurality of sieve holes are uniformly arranged on the housing; A biochar inner cylinder coaxially arranged inside the housing, and the outer periphery of the biochar inner cylinder is adapted to the inner periphery of the housing; A steel sieve arranged at the center of the biochar inner cylinder; A mixed soil filled in the annulus between the biochar inner cylinder and the steel sieve and inside the steel sieve; A voltage monitor, the negative electrode and the positive electrode of which are respectively electrically connected to the biochar inner cylinder and the steel sieve; Among them, the mixed soil is composed of an electrogenic bacterium agent and clean soil. The addition amount of the electrogenic bacterium agent in the mixed soil is 3-8%, and the microbial concentration of the electrogenic bacterium agent is 10 7 -10 9 CFU / mL, and the electrogenic bacterium is a petroleum hydrocarbon-degrading bacterial community.

2. The on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil according to claim 1, characterized in that: A drill bit is provided below the housing.

3. The on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil according to claim 1 or 2, characterized in that: A detachable upper cover is provided at the opening of the housing.

4. The on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil according to claim 3, characterized in that: The inner diameter of the housing is 4 - 6 cm, the depth is 8 - 10 cm, the thickness is 0.2 - 0.5 cm, and the sieve holes are 10 - 50 mesh; the outer diameter of the biochar inner cylinder is 4 - 6 cm, the height is 8 - 10 cm, and the thickness is 1 - 2 cm; the outer diameter of the steel sieve is 1 - 2 cm, the height is 8 - 10 cm, the thickness is 0.2 - 0.5 cm, and the sieve is 10 - 50 mesh; the radius of the upper cover is 4 - 6 cm, and the thickness is 0.2 - 0.5 cm.

5. The on-line monitoring equipment for petroleum hydrocarbon pollution in vadose zone soil according to claim 4, characterized in that: The inner diameter of the housing is 5 cm, the depth is 9 cm, the thickness is 0.25 cm, and the sieve holes are 20 mesh; the outer diameter of the biochar inner cylinder is 5 cm, the height is 9 cm, and the thickness is 1.5 cm; the outer diameter of the steel sieve is 1.5 cm, the height is 9 cm, the thickness is 0.25 cm, and the sieve is 20 mesh; the radius of the upper cover is 5 cm, and the thickness is 0.25 cm.

6. The on-line monitoring device for petroleum hydrocarbon pollution in vadose zone soil according to claim 1, characterized in that: The addition amount of the electricity-producing bacteria agent in the mixed soil is 5%, and the microbial concentration of the electricity-producing bacteria agent is 10 8 CFU / mL.

7. An on-line monitoring method for petroleum hydrocarbon pollution in vadose zone soil, which uses the on-line monitoring equipment for petroleum hydrocarbon pollution in vadose zone soil described in any one of claims 1-6, is characterized in that, Including the following steps: S1. Add the electricity-producing bacteria agent into the clean soil at an addition amount of 3-8% to make a mixed soil, and then fill the annulus between the biological carbon inner cylinder and the steel screen and the inside of the steel screen with the mixed soil; wherein, the microbial concentration of the electricity-producing bacteria agent is 10 7 -10 9 CFU / mL, and the electricity-producing bacteria is a petroleum hydrocarbon-degrading bacterial community; S2. Conduct starvation pretreatment on the on - line monitoring equipment for petroleum hydrocarbon pollution in the vadose zone soil; S3. Take 6 portions of clean soil, and then add petroleum hydrocarbons to each portion of clean soil respectively. After stirring evenly, 6 portions of standard soil are prepared, and the petroleum hydrocarbon concentration in each portion of standard soil is 100 mg / kg, 200 mg / kg, 300 mg / kg, 400 mg / kg, 500 mg / kg, 600 mg / kg; then place the 6 portions of standard soil in 6 containers with open upper ends respectively to simulate the formation environment and prevent water evaporation; then take 6 on - line monitoring equipment for petroleum hydrocarbon pollution in the vadose zone soil after starvation pretreatment, and bury them one by one in the 6 containers filled with standard soil respectively, and keep them at the same temperature as the soil to be measured. Pay attention to the voltage change. When the voltage reaches the peak value, record the maximum voltage value, make a standard curve of maximum voltage - petroleum hydrocarbon concentration, and obtain the fitting equation as: y = 0.409x + 13.46, R 2 = 0.95 (1) In formula (1): y is the maximum voltage, mv; x is the petroleum hydrocarbon concentration, mg / kg; S4. Take another on - line monitoring equipment for petroleum hydrocarbon pollution in the vadose zone soil after starvation pretreatment, put it into the formation to be measured, record the maximum voltage value, and obtain the pollution degree of petroleum hydrocarbons in the formation to be measured according to the fitting equation.

8. The on-line monitoring method for petroleum hydrocarbon pollution in vadose zone soil according to claim 7, characterized in that, In step S2, the method of the starvation pretreatment is: electrically connect the negative electrode and the positive electrode of the voltage monitor to the biochar inner cylinder and the steel sieve respectively, and bury the on - line monitoring equipment for petroleum hydrocarbon pollution in the vadose zone soil in the clean soil until the voltage is stable.

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