A method for remediating a contaminated site and a method for evaluating a degradation period

Abstract

The application discloses a contaminated site remediation method and a degradation period evaluation method, and comprises the following steps: step 1, determining a pollution range, setting a sampling point in the contaminated site, taking a groundwater sample at the sampling point, and measuring the concentration of an electron acceptor and the concentration of a degradation product; step 2, according to the measured concentrations of various indexes at different periods, calculating the cumulative percentage of various indexes at different periods, taking the concentration of the electron acceptor or the concentration of the degradation product as the horizontal coordinate, and the corresponding cumulative probability as the vertical coordinate, and drawing a cumulative probability distribution curve of each monitoring index; step 3, threshold range acquisition: according to the cumulative probability distribution curves of different electron acceptors or degradation products obtained in step 2, the threshold range of the stable section of different electron acceptors or degradation products is acquired; step 4, calculating the degradation capacity; and step 4, calculating the aquifer biodegradation rate. The method is specific for utilizing the conversion relationship between the electron acceptor and the pollutants, and can quantitatively evaluate the degradation capacity and the degradation rate of the pollutants.

Description

[0001] The present application is a divisional application of the parent application "Method for evaluating the biodegradation rate of aquifer in contaminated site", the filing date of the parent application is January 30, 2021, and the application number is 2021101318632. TECHNICAL FIELD

[0002] The present application relates to the technical field of groundwater remediation, in particular to a contaminated site remediation method and a degradation period evaluation method. BACKGROUND

[0003] There are many types of current groundwater remediation technologies, among which the monitoring natural attenuation technology is a low-cost and environmentally friendly in-situ remediation technology. This technology is increasingly mature and has broad application prospects. Biodegradation is the core of natural attenuation remediation technology, and evaluating the natural biodegradation capacity of groundwater in the site is the prerequisite for determining whether the site can be naturally attenuated and repaired. At present, the evaluation methods for the natural attenuation capacity of organic pollutants in groundwater at home and abroad mainly include pollutant concentration trend analysis method, microbiological method, microcosm experiment method, stable isotope analysis method, computer simulation method, etc. However, these methods have problems such as high time and operation cost, inability to quantitatively estimate the degradation capacity of the site, limited direct application of laboratory test results, great influence of contaminated source components, high testing cost, strong uncertainty, etc. The hydrogeochemical index analysis method can quantitatively estimate the natural attenuation capacity of the site by monitoring the geochemical index (electron acceptor / degradation product) indicating microbial biodegradation, and the testing method is simple and the cost is low. Monitoring the electron acceptor to evaluate the degradation capacity of the contaminated aquifer is also the core concept method of monitoring natural attenuation.

[0004] When calculating the natural attenuation capacity of the site by the hydrogeochemical index analysis method, the calculation of the consumption / production value of the electron acceptor / degradation product is generally the difference between the concentration of the electron acceptor / product in the background well and the concentration of the electron acceptor / product in the monitoring well where degradation occurs. In recent years, the research on this method generally selects the lowest pollution degree or the highest electron acceptor concentration in the upstream of the background well as the electron acceptor concentration in the natural groundwater of the site, and the concentration of the electron acceptor / product in the monitoring well where degradation occurs is calculated based on the statistical method to obtain the average value or the expected value. These calculation methods may overestimate the degradation capacity of the site, and fail to consider the different degradation types under the different redox effects dominated by the microorganisms in the site area. In view of the above problems in the process of calculating the degradation rate, it is necessary to find a method for conservatively evaluating the degradation rate of the contaminated site based on microbial degradation. SUMMARY

[0005] The purpose of the present application is to provide a method for calculating the biodegradation capacity of the aquifer in the contaminated site, which overcomes the problem of overestimating the degradation capacity of the site in the prior art.

[0006] Another object of the present application is to provide a method for evaluating the biodegradation rate of the aquifer of a contaminated site, in order to overcome the excessive evaluation of the site degradation capacity in the prior art.

[0007] Another object of the present application is to provide a method for remediation of a contaminated site.

[0008] Another object of the present application is to provide a method for evaluating the degradation period of a contaminated site.

[0009] The technical solution adopted to achieve the objects of the present application is as follows:

[0010] A method for calculating the biodegradation capacity of the aquifer of a contaminated site, comprising the following steps:

[0011] Step 1, determining the pollution range, setting sampling points in the contaminated site, taking groundwater samples at the sampling points, and measuring the concentrations of electron acceptors and degradation products;

[0012] Step 2, calculating the cumulative percentage of each indicator for one or more periods according to the measured concentrations of each indicator for one or more periods, and drawing a cumulative probability distribution curve of each monitoring indicator with the concentration of the electron acceptor or the degradation product as the abscissa and the corresponding cumulative probability as the ordinate;

[0013] Step 3, threshold range acquisition:

[0014] According to the cumulative probability distribution curves of different electron acceptors or degradation products obtained in step 2, the threshold range of the stable stage of different electron acceptors or degradation products is obtained;

[0015] Step 4, calculating the degradation capacity:

[0016] The integral method is used to calculate the biodegradation capacity of a certain electron acceptor, and the expression formula is:

[0017]

[0018] EBC x is the degradation capacity of a certain electron acceptor, with the unit of mg / L; x represents the electron acceptor O2, NO3 - , SO4 2- , Fe 3+ , Mn 4+ , CO2; C X (p) represents the concentration of the electron acceptor when the cumulative probability is p; p1 and p2 are the cumulative percentages corresponding to the threshold values of the electron acceptor in the stable stage, and F is the utilization coefficient of petroleum pollutants, with the unit of mg / mg.

[0019] In the technical scheme, in the step 1, the sampling points are set, the hydrogeological conditions and the pollutant distribution of the site are determined according to the site investigation, different monitoring areas are divided, at least three monitoring wells are selected in each monitoring area to form a monitoring well network to sample and monitor the underground water.

[0020] In the technical scheme, the monitoring area includes a background area or a flanking area, an upstream area, a source area and a downstream area.

[0021] In the technical scheme, the electron acceptor in the step 1 includes DO, NO3 - and / or SO4 2- .

[0022] In the technical scheme, the degradation product in the step 1 includes Fe 2+ , Mn 2+ and / or CH4.

[0023] In the technical scheme, the cumulative probability distribution curve is divided into four stages of adaptation, enhancement, stability and attenuation.

[0024] In the technical scheme, the cumulative probability distribution curve is a segmented straight line with multiple obvious turning points, the intersection of two straight lines is regarded as the threshold value of each degradation stage, wherein the cumulative probability distribution curve of the electron acceptor from top to bottom corresponds to the adaptation section, the growth section, the stability section and the attenuation section, and the cumulative probability distribution curve of the degradation product is opposite.

[0025] In the technical scheme, the coefficients of the electron acceptor consumed by the aerobic action, the denitrification action, the manganese reduction action, the iron reduction action, the desulfurization action and the methane production action for degrading the petroleum pollutant are 3.14, 4.9, 10.7, 21.8, 4.7 and 0.78 respectively.

[0026] In the technical scheme, the total sum expression of the degradation ability of all electron acceptor microorganisms is as follows:

[0027]

[0028] Another aspect of the present application is a method for evaluating the biodegradation rate of an aquifer in a contaminated site, which comprises the method for calculating the biodegradation ability of the aquifer in the contaminated site and the following step 5.

[0029] Step 5, the total sum expression of the degradation ability of all electron acceptor microorganisms is as follows:

[0030]

[0031] The biodegradation rate of the aquifer is calculated from the main flow direction of the electron acceptor in the underground water and the lateral recharge renewal flow, and the expression is as follows:

[0032]

[0033] In the formula, v bio is the degradation rate of all electron acceptors in the aquifer, in kg / a; Q is the lateral recharge flow of the main flow direction of the electron acceptors in the groundwater, in m 3 / d.

[0034] Another aspect of the present application is a contaminated site remediation method, comprising the contaminated site aquifer biodegradability calculation method, and an evaluation and remediation step;

[0035] The evaluation and remediation step comprises:

[0036] Step 1.1, calculating the degradation capacity proportion provided by each electron acceptor, each

[0037] Step 1.2, according to the degradation capacity proportion, supplementing the salt of the electron acceptor with a high degradation capacity proportion in the contaminated site to strengthen the natural attenuation capacity of the site.

[0038] Another aspect of the present application is a contaminated site degradation period evaluation method, comprising the contaminated site aquifer biodegradation rate evaluation method, and a degradation period evaluation step; the degradation period t=M / v bio , wherein M is the amount of pollutant leakage.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] 1. The present application is based on the growth and metabolism principle of degrading microorganisms, and the type of microbial degradation can also be divided into four stages of adaptation, growth, stability and decay. The consumption of electron acceptor ability in each stage is different, which is reflected in the piecewise function in the cumulative probability distribution curve of a certain electron acceptor. Since the strong consumption of electron acceptor by microorganisms mainly occurs in the stable segment, the present application conservatively evaluates the degradation type of the site (aerobic stage, denitrification stage, manganese reduction stage, iron reduction stage, sulfate reduction stage and methanogenesis stage) in the stable segment.

[0041] 2. The hydrogeochemical evaluation method is to analyze the current groundwater environmental conditions on the pollutant purification capacity according to the concentration change of the electron acceptors at different positions of the pollution plume, and then evaluate the sustainability of the natural attenuation capacity of the aquifer.

[0042] 3. The method specifically uses the transformation relationship between the electron acceptor and the pollutants to quantitatively evaluate the degradation capacity and the degradation rate of the pollutants. Therefore, the change of the concentration of the electron acceptor in the stable stage of different degradation stages of the microorganism is combined with the hydrogeochemical method to calculate the biodegradation capacity and the degradation rate in the contaminated site, so that the natural attenuation capacity of the site can be evaluated to the greatest extent, and data guidance can be provided for the subsequent enhanced natural attenuation remediation technology of the site. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a cumulative probability distribution curve, wherein (a) is a cumulative probability distribution curve of an electron acceptor, and (b) is a cumulative probability distribution curve of a degradation product.

[0044] Figure 2 is a schematic diagram of the consumption of different electron acceptors / products.

[0045] Figure 3 is a cumulative probability distribution curve of each electron acceptor / degradation product in Example 2.

[0046] Figure 4 is a cumulative probability distribution curve of each electron acceptor / degradation product in Example 3.

[0047] Figure 5 is a cumulative probability distribution curve of each index in Example 4. DETAILED DESCRIPTION

[0048] The application will be further described below in conjunction with specific examples. It should be understood that the specific examples described herein are only used to explain the application and do not limit the application.

[0049] Example 1

[0050] A method for evaluating the biodegradation rate of an aquifer in a contaminated site comprises the following steps:

[0051] Step 1, determining the pollution range, measuring the hydrogeochemical indexes, wherein the hydrogeochemical indexes include the concentration of the electron acceptor and the concentration of the degradation product:

[0052] According to the site investigation, the hydrogeological conditions and the distribution of the pollutants in the site are determined, different monitoring areas (background / flank area, upstream area, source area, downstream area) are divided, and at least 3 monitoring wells are selected in each monitoring area to form a monitoring well network for monitoring the groundwater.

[0053] The groundwater samples at different times and different positions in the contaminated site are collected by using a Bell tube, an air bag pump, etc., and the inorganic chemical indexes DO, NO3 - , SO4 2- , Fe 2+ , and Mn 2+, CH4concentration, among which the first three are electron acceptors and the last three are degradation products.

[0054] Step 2, cumulative probability distribution curve based on microbial growth law

[0055] Microorganisms degrade pollutants using certain electron acceptors, which can be divided into four stages: adaptation, enhancement, stability and attenuation. Therefore, the cumulative probability distribution curve should show a segmented straight line with multiple turning points, and the intersection of two straight lines is considered as the threshold of each degradation stage. According to the measured concentrations of each index at different times, the cumulative percentage of each index at different times is calculated, and the cumulative probability distribution curve of each monitoring index is drawn with the electron acceptor / degradation product concentration as the horizontal coordinate and the corresponding cumulative probability as the vertical coordinate. Among them, the segmented curve of the electron acceptor from top to bottom corresponds to the adaptation segment, the growth segment, the stability segment and the attenuation segment, and the degradation product is opposite, as shown in Figure 1 .

[0056] Step 3, threshold range acquisition

[0057] According to the cumulative probability distribution curve of different electron acceptors / degradation products, the threshold range of each stage of different electron acceptors / degradation products is obtained.

[0058] Table 1 Threshold of electron acceptor / product concentration in different degradation stages

[0059] Degradation phase Electron acceptor concentration threshold Degradation product concentration threshold Accommodation phase C3-C4 0～C1 Growth phase C2-C3 C1-C2 Stationary phase C1-C2 C2-C3 Decay phase 0～C1 C3-C4

[0060] Step 4, degradation capacity and degradation rate evaluation

[0061] According to the cumulative probability distribution curve, the stable stage concentration range of different electron acceptors / degradation products is obtained, and the integral method is used to calculate the biodegradation capacity of a certain electron acceptor, and the expression formula is:

[0062]

[0063] EBC x is the degradation capacity of a certain electron acceptor (mg / L); x refers to the electron acceptors O2, NO3 - , SO4 2- , Fe 3+ , Mn 4+ , CO2; C X (p) represents the concentration of the electron acceptor when the cumulative probability is p; F is the utilization coefficient of petroleum pollutants (represented by C n H n ) (mg / mg), from the perspective of microbial metabolism, i.e. aerobic action, denitrification, manganese reduction, iron reduction, desulfurization and methanogenesis, the degradation coefficient of petroleum pollutants using electron acceptors is 3.14, 4.9, 10.7, 21.8, 4.7 and 0.78, respectively.

[0064] The summation expression for the microbial degradation capacity of all electron acceptors is:

[0065]

[0066] Calculate the percentage of degradation capacity provided by each electron acceptor, each That is, the ratio of the degradation capacity of electron acceptors or degradation products to the total degradation capacity.

[0067] The level of degradation capacity provided by electron acceptors can serve as a reference for enhancing the natural degradation capacity of a field in the later stages. That is, if the degradation capacity provided by a certain type of electron is relatively high in the field, then an electron acceptor salt of that type can be added to the field to enhance its natural degradation capacity.

[0068] The aquifer degradation rate is calculated from the mainstream lateral recharge rate (flow rate) of electron acceptors in groundwater, and the expression is:

[0069]

[0070] In the formula, v bio Q represents the degradation rate of all electron acceptors in the aquifer (kg / a); Q represents the mainstream lateral recharge flow rate of electron acceptors in groundwater (m³). 3 / d).

[0071] Assuming no human intervention has been implemented to address aquifer contamination, the amount of pollutant leakage obtained from the site investigation can be used to conservatively assess the degradation time of organic pollutants in the biodegradable site. This provides a basis for decision-making in assessing the feasibility of natural attenuation at contaminated sites and offers empirical evidence and fundamental data for in-situ groundwater remediation.

[0072] Example 2

[0073] A method for assessing the natural degradation capacity of a contaminated site includes the following steps:

[0074] Groundwater samples were collected from different monitoring areas (background / flank area, upstream area, source area, and downstream area) at a contaminated site. The concentrations of DO and NO3 in the samples were then determined. - SO4 2- Fe 2+ Mn 2+ CH4 concentration was analyzed, and cumulative distribution probability curves of electron acceptors / degradation products were plotted at different time points. Because H2O2 was used for oxidative remediation at this site, affecting the dissolved oxygen content and distribution characteristics in the groundwater, and because CH4 gas is difficult to collect and detect at this site, DO and CH4 were not analyzed.

[0075] like Figure 3As shown, the cumulative probability distribution curves obtained from the plotted electron acceptor / degradation product can reveal the threshold ranges corresponding to different stable segments of electron acceptors / products, NO3. - The concentration range is 2.99-9.83 mg·L. -1 Mn 2+ The concentration range is 1.85-5.13 mg·L. -1 Fe 2+ The concentration range is 0.9-1.02 mg·L⁻¹ -1 SO4 2- The concentration range was 113.92-193.86 mg·L⁻¹ -1 .

[0076] Based on the obtained threshold range, the electron acceptor degradation capacity of the aquifer during this period was calculated to be 18.41 mg / L, and the degradation rate was 886 kg / a.

[0077] Example 3

[0078] Groundwater samples were collected from monitoring wells in different monitoring areas of a certain site in March of a certain year, and the NO3 content in the water samples was analyzed. - SO4 2- Fe 2+ Mn 2+ The concentrations of electron acceptors and degradation products were measured. Based on the electron acceptor / degradation product concentrations of each indicator, a cumulative probability curve was plotted with electron acceptor / product concentration on the x-axis and cumulative percentage on the y-axis.

[0079] like Figure 4 As shown, based on the plotted cumulative probability distribution curve, the threshold range corresponding to different electron acceptor / product stable segments can be obtained. - The concentration range is 6.15-36.77 mg·L⁻¹. -1 Mn 2+ The concentration range is 1.58-6.89 mg·L. -1 Fe 2+ The concentration range is 0.16-0.3 mg·L. -1 SO4 2- The concentration range is 111.3-186.7 mg·L. -1 .

[0080] Based on the obtained threshold range, the electron acceptor degradation capacity of the aquifer during this period was calculated to be 22.55 mg / L, and the degradation rate was 1086.4 kg / a, according to the formula.

[0081] Example 4

[0082] In April of a certain year, groundwater samples were collected from monitoring wells in different monitoring areas of a certain site, and the NO3 content in the water samples was analyzed. - SO4 2- Fe 2+ Mn 2+ The concentrations of electron acceptors and degradation products were measured. Based on the electron acceptor / degradation product concentrations of each indicator, a cumulative probability distribution curve was plotted with the concentration of each indicator on the x-axis and the cumulative percentage on the y-axis.

[0083] like Figure 5 As shown, according to the cumulative probability distribution curve ( Figure 5 It can obtain the threshold range corresponding to the stable segment of different indicators, NO3 - The concentration range is 6.15-43.39 mg·L⁻¹. -1 Mn 2+ The concentration range is 1.82-6.28 mg·L⁻¹ -1 Fe 2+ The concentration range is 0.62-2.91 mg·L⁻¹ -1 SO4 2- The concentration range was 111.3-141.69 mg·L⁻¹ -1 .

[0084] Based on the obtained threshold range, the electron acceptor degradation capacity of the aquifer during this period was calculated to be 14.17 mg / L, and the degradation rate was 682.8 kg / a.

[0085] Examples 2-4 represent three phases of testing. The calculated aquifer biodegradation rates were similar across the three phases, demonstrating the stability and usability of the method.

[0086] The average biodegradation capacity of the aquifer at this site, calculated over three phases, is 18.38 mg / L. A conservative estimate of the electron acceptor degradation rate in the aquifer is 885.39 kg / a. This method calculates an organic matter degradation rate lower than the previous non-conservative assessment result (1539 kg / a) obtained using isotope analysis. The results from both methods are similar, demonstrating the feasibility of this method.

[0087] Based on the proportion of degradation capacity provided by each electron acceptor, desulfurization (SO4) 2- 71.68%), denitrification (NO3) - 28.11%), manganese reduction (Mn) 4+ 2.21%), iron reduction (Fe 3+ The degradation rates (0.21%) were 634.64 kg / a, 248.86 kg / a, 19.59 kg / a, and 1.87 kg / a, respectively. In this site, the electron acceptor desulfurization process provided a relatively high proportion of degradation; therefore, in the later stages, sulfate electron acceptors could be added to the site to enhance the natural degradation process.

[0088] Under the current site existing conditions, the degradation time of the site oil pollutants is conservatively calculated. The average method of methyl tert-butyl ether (MTBE) is used to estimate the oil leakage amount M of the site as 4160 kg, and the degradation time t = M / v is conservatively calculated as 4.7 a.

[0089] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for remediating a contaminated site, characterized in that, The method comprises the following steps: The method for calculating the biodegradation capacity of the contaminated site aquifer comprises the following steps: Step 1, determining the pollution range, setting sampling points in the contaminated site, taking groundwater samples at the sampling points, and measuring the concentrations of electron acceptors and degradation products; Step 2, according to the concentrations of the indicators measured at one or more time periods, calculating the cumulative percentage of the indicators at one or more time periods, taking the concentration of the electron acceptor or the degradation product as the horizontal coordinate, and the corresponding cumulative probability as the vertical coordinate, and drawing a cumulative probability distribution curve of each monitoring indicator; Step 3, threshold range acquisition: According to the cumulative probability distribution curves of different electron acceptors or degradation products obtained in step 2, the threshold range of the stable stage of different electron acceptors or degradation products is obtained; the cumulative probability distribution curve is divided into four stages of adaptation, enhancement, stability and attenuation, and the cumulative probability distribution curve is a segmented straight line with multiple obvious turning points, and the intersection point of the two straight lines is regarded as the threshold of each degradation stage, wherein the cumulative probability distribution curve of the electron acceptor is from top to bottom, corresponding to the adaptation stage, the growth stage, the stable stage and the attenuation stage, and the cumulative probability distribution curve of the degradation product is opposite; step 4, calculating the degradation capacity: The biodegradation capacity of a certain electron acceptor is calculated by using the integral method, and the expression formula is: EBC x degradation capacity of certain electron acceptor, unit: mg / L; x refers to electron acceptor O2, NO3 - , SO4 2- , Fe 3+ , Mn 4+ , CO2; C X (p) represents the concentration of electron acceptor when the cumulative probability is p; p1 and p2 are the cumulative percentages corresponding to the threshold value of electron acceptor in the stable stage, and F is the utilization coefficient of petroleum pollutants, unit: mg / mg; The repair step comprises: Step 1.1, calculating the proportion of degradation capacity provided by each electron acceptor, and the degradation capacity provided by each electron acceptor Step 1.2, according to the degradation capacity proportion, supplementing the salt of the electron acceptor with high degradation capacity proportion in the contaminated site to strengthen the natural attenuation capacity of the site.

2. The method of remediating a contaminated site according to claim 1, wherein, When the sampling points are set in step 1, the hydrogeological conditions and the distribution of pollutants in the site are determined according to the site investigation, different monitoring areas are divided, and at least three monitoring wells are selected in each monitoring area to form a monitoring well network for sampling and monitoring of groundwater.

3. The method of remediating a contaminated site according to claim 2, wherein, The monitoring area comprises a background area, a side area, an upstream area, a source area and / or a downstream area.

4. The method of remediating a contaminated site according to claim 1, wherein, The electron acceptor in step 1 includes DO, NO3 - and / or SO4 2- .

5. The method of remediating a contaminated site according to claim 1, wherein, The degradation products in step 1 include Fe 2+ , Mn 2+ and / or CH4.

6. The method of remediating a contaminated site according to claim 1, wherein, The coefficients of electron acceptors consumed by aerobic action, denitrification, manganese reduction, iron reduction, desulfurization and methanogenesis for degrading petroleum pollutants are 3.14, 4.9, 10.7, 21.8, 4.7 and 0.78 respectively.

7. The method of remediating a contaminated site according to claim 1, wherein, The expression formula of the total biodegradation capacity of all electron acceptor microorganisms is:

8. A method for assessing the degradation time of a contaminated site, characterized in that, The method comprises the following steps: The method for calculating the biodegradation capacity of the contaminated site aquifer comprises the following steps: Step 1, determining the pollution range, setting sampling points in the contaminated site, taking groundwater samples at the sampling points, and measuring the concentrations of electron acceptors and degradation products; Step 2, according to the concentrations of the indicators measured at one or more time periods, calculating the cumulative percentage of the indicators at one or more time periods, taking the concentration of the electron acceptor or the degradation product as the horizontal coordinate, and the corresponding cumulative probability as the vertical coordinate, and drawing a cumulative probability distribution curve of each monitoring indicator; Step 3, threshold range acquisition: According to the cumulative probability distribution curve of different electron acceptors or degradation products obtained in step 2, the threshold range of the stable stage of different electron acceptors or degradation products is obtained; the cumulative probability distribution curve is divided into four stages of adaptation, enhancement, stability and attenuation, the cumulative probability distribution curve is a segmented straight line with multiple obvious turning points, and the intersection point of two straight lines is regarded as the threshold value of each degradation stage, wherein the cumulative probability distribution curve of the electron acceptor corresponds to the adaptation stage, the growth stage, the stable stage and the attenuation stage from top to bottom, and the cumulative probability distribution curve of the degradation product is opposite to it; Step 4, calculate the degradation capacity: The integral method is used to calculate the biodegradation capacity of the electron acceptor, and the expression formula is: EBC x degradation capacity of certain electron acceptor, unit: mg / L; x refers to electron acceptor O2, NO3 - , SO4 2- , Fe 3+ , Mn 4+ , CO2; C X (p) represents the concentration of electron acceptor when the cumulative probability is p; p1 and p2 are the cumulative percentages corresponding to the threshold value of electron acceptor in the stable stage, and F is the utilization coefficient of petroleum pollutants, unit: mg / mg; The expression formula of the total degradation capacity of all electron acceptor microorganisms is: The biodegradation rate of the aquifer is calculated by the main flow and lateral recharge update flow of the electron acceptor in the groundwater, and the expression is: where v bio is the degradation rate of all electron acceptors in the aquifer, in kg / a; Q is the main flow of electron acceptors in groundwater lateral recharge update flow, in m 3 / d; Step 6, under the premise that the degradation rate at the site is constant, the degradation time t = M / v bio where M is the amount of pollutant leakage.

9. The method for evaluating the degradation period of a contaminated site according to Claim 8, wherein The pollutant is a petroleum spill.

10. The method for evaluating the degradation period of a contaminated site according to Claim 8, wherein The pollutant leakage amount is estimated by the mean value method of methyl tert-butyl ether.

Images