CN116523408A - Evaluation method of contaminated site soil remediation technology - Google Patents

Abstract

The invention relates to an evaluation method of a contaminated site soil remediation technology, which comprises the steps of firstly screening the contaminated site soil remediation technology according to a MOORA method of combining and weighting subjective weight and objective weight, and obtaining a preferable screening result; performing carbon footprint analysis on a plurality of repair technologies positioned at the front part of the optimized screening result, calculating the total carbon emission of the repair technologies, and sequencing according to the total carbon emission of the repair technologies; and combining the sorting of the preferred screening results and the sorting of the carbon footprint analysis to obtain the optimal evaluation result of the contaminated site soil remediation technology. The invention has wide application range and flexible use, and can lead the repair technology to be correspondingly lower in carbon, more green and more sustainable in the repair process, thereby meeting the requirement of environmental protection, being beneficial to the development of repair work, judging and evaluating the overall quality of the repair technology in multiple aspects, and leading the best evaluation result of the obtained repair technology to be more scientific and reliable.

Description

An evaluation method for soil remediation technology at contaminated sites

Technical Field

The present invention relates to the technical field of environmental governance, and in particular to an evaluation method for soil remediation technology of contaminated sites.

Background Art

With the rapid development of cities, the urban area is expanding faster and faster. Many former suburbs of cities have become urban areas, and rural areas have become towns. Urbanization is a process of secondary development and utilization of land. When using suburban or rural land, there is a large amount of unusable contaminated land, which is a major problem hindering the process of urbanization. Industrial and mining wasteland, landfills, sludge disposal sites, etc. are all very large contaminated sites in suburban or rural areas. With the expansion of urban areas, soil remediation of these contaminated sites is an extremely arduous battle, and the evaluation and selection of corresponding remediation technologies play an important role.

Soil remediation technologies for contaminated sites include thermal treatment technology, chemical treatment technology, biological treatment technology, etc. Due to the continuous improvement of environmental protection requirements, the remediation technologies selected for evaluation are no longer just for degrading soil pollutants, but need to develop in a more comprehensive direction such as green and environmentally friendly. Therefore, the evaluation and selection of remediation technologies need to be selected based on actual conditions. However, the evaluation of various existing soil remediation technologies for contaminated sites mainly uses expert scoring methods, and subjective factors play a dominant role in the results. It is not scientific and reasonable, and it is difficult to obtain the best evaluation results.

Summary of the invention

To this end, the technical problem to be solved by the present invention is to overcome the defects that the evaluation of various soil remediation technologies for contaminated sites in the prior art mainly adopts the expert scoring method, subjective factors play a dominant role in the results, it is not scientific and reasonable, and it is difficult to obtain the best evaluation results.

In order to solve the above technical problems, the present invention provides an evaluation method for soil remediation technology of contaminated sites, comprising:

S1: The MOORA method, which combines subjective and objective weights, is used to screen soil remediation technologies for contaminated sites and obtain the optimal screening results;

S2: Carbon footprint analysis is performed on the top several restoration technologies in the preferred screening results, and they are ranked as follows:

S21: Calculate the carbon emissions C ₁ of material consumption using the formula:

Where f is the number of material types, CEA _t is the carbon emission factor of the t-th material, Q _t is the usage of the t-th material, and b _t is the recycling factor of the t-th material;

S22: Calculate the carbon emissions C ₂ from energy consumption using the formula:

Among them, V is the number of energy types, CEA _g is the carbon emission factor of the g-th energy, and Q _g is the usage of the g-th energy;

S23: Calculate the total carbon emissions CE of the restoration technology based on the carbon emissions _C1 of material consumption and the carbon emissions _C2 of energy consumption. The formula is:

CE＝C ₁ +C ₂

S24: Rank the top several restoration technologies in the preferred screening results according to the total carbon emissions CE, the smaller the total carbon emissions, the better;

S3: Combine the ranking of the optimal screening results with the ranking of the carbon footprint analysis to obtain the best evaluation results of the soil remediation technology for contaminated sites.

In one embodiment of the present invention, the MOORA method weighted by the combination of subjective weight and objective weight is used to screen the soil remediation technology of the contaminated site and obtain the optimal screening result. The specific steps are as follows:

S11: constructing a preliminary screening database for contaminated site soil remediation technologies, inputting the types of pollutants in the contaminated site soil into the preliminary screening database, screening out several candidate remediation technologies, and obtaining the initial screening results;

S12: constructing a screening index system using the analytic hierarchy process in the initial screening results, wherein the screening index system includes a target layer, an index layer, a factor layer and a scheme layer, wherein the target layer is to screen out the best evaluation result of the soil remediation technology for contaminated sites, the index layer includes several indicators, the factor layer includes several factors affecting the indicators, and the scheme layer is the alternative schemes for the soil remediation technology for contaminated sites;

S13: Input the subjective scoring parameters of each factor, and calculate the subjective weight of each factor through the hierarchical analysis method;

S14: according to the candidate restoration technologies in the initial screening results, input the scoring parameters of the factors corresponding to each candidate restoration technology, and express the scoring parameters with triangular fuzzy numbers;

S15: Calculate the objective weight of the factor by using the entropy method according to the scoring parameters represented by the triangular fuzzy numbers of the factors corresponding to each candidate restoration technology;

S16: Combine the subjective weight and the objective weight, and assign weights to obtain the combined weight;

S17: Combined with the scoring parameters and combined weights of the corresponding factors of each candidate remediation technology, the addition ratio of the candidate remediation technology is calculated and ranked to obtain the preferred screening results of the soil remediation technology for contaminated sites.

In one embodiment of the present invention, the step S3 combines the ranking of the preferred screening results and the ranking of the carbon footprint analysis, and uses the weighted queuing scoring method to calculate the final score. The specific steps are as follows:

S31: sorting the optimization screening results and the restoration technologies in the carbon footprint analysis according to their merits to obtain N ranking sequences, and taking the average of the rankings they should have occupied for the tied rankings;

S32: Calculate the individual score K _o of the oth restoration technology according to the ranking of the restoration technology, and the formula is:

Among them, v is the ranking number;

S33: Weight the individual scores and calculate the total score K, where _Lo is the weight of the repair technology, and the formula is:

S34: Sort by the total score K to determine the quality. The higher the score, the better. The best evaluation result of soil remediation technology for contaminated sites is obtained.

In one embodiment of the present invention, in step S13, the subjective weight of each factor is calculated by using the hierarchical analysis method, and the calculation steps are as follows:

S131: Assume that there are n factors. According to the scale table, compare each factor pairwise to determine the relative importance of each factor. _aij represents the ratio of the influence of factor B _i and factor B _j on target A. Construct a pairwise comparison judgment matrix A. The formula is:

Where, i＝1,2,...,n; j＝＝1,2,...,n;

S132: Use the root-finding method to calculate the approximate value w _i of the eigenvector of the judgment matrix. The formula is:

After standardizing the feature vector, we get the subjective weight vector w, which is:

w＝(w ₁ ,w ₂ ,…, _wn ) ^T

S133: Calculate the consistency factor CI, the formula is:

in,

Introducing random consistency ratio CR

When the consistency ratio CR is less than the threshold, the subjective weight is correct and reasonable; when the consistency ratio CR is greater than or equal to the threshold, the subjective weight is incorrect and unreasonable, and the subjective scoring parameters and judgment matrix of each factor are readjusted, and steps S121, S122 and S123 are repeated until the consistency ratio CR is less than the threshold.

In one embodiment of the present invention, in step S14, according to the candidate restoration technologies in the initial screening results, the scoring parameters of the factors corresponding to each candidate restoration technology are input, and the scoring parameters are represented by triangular fuzzy numbers, specifically:

x _ab = (x′ _ab , x″ _ab , x″′ _ab )

Among them, x′ _ab is the lower bound of the triangular fuzzy number, which is the most conservative estimate; x″ _ab is the most likely estimate; x″′ _ab is the upper bound of the triangular fuzzy number, which is the most optimistic estimate, a＝1,2,...,m; b＝1,2,...,n.

In one embodiment of the present invention, in step S15, the objective weight of the factor is calculated by the entropy method according to the scoring parameters represented by the triangular fuzzy numbers of the factors corresponding to each candidate restoration technology, and the calculation steps are as follows:

S151: Assume that the evaluation matrix X is composed of m alternative remediation technologies for contaminated site soil and the original data of n factors, and the formula is:

Wherein, a＝1,2,...,m；b＝1,2,...,n；

S152: Defuzzify the triangular fuzzy number and convert it into a definite value. The conversion formula is as follows:

S153: Each factor is normalized according to the number of each option to obtain a normalized matrix R, the formula is:

R＝( _r′ab ) _m×n

For the positive factors among the factors:

For negative factors:

S154: Calculate the proportion p _ab of the ath candidate repair technology factor value under the bth factor, and the formula is:

S155: Calculate the entropy value e _b of the b-th factor, the formula is:

in,

S156: Calculate the information entropy redundancy d _b , the formula is:

_db = 1- _eb

S157: Calculate the objective weight u _b of each factor, the formula is:

In one embodiment of the present invention, in step S16, the subjective weight _wj and the objective weight _ub are combined and weighted according to the weight ratio h[ _wj , _ub ]={0.5,0.5} to obtain the combined weight _hj , which is:

h _j =0.5×w _j +0.5× _ub .

In one embodiment of the present invention, in step S17, the MOORA method is used to calculate and sort the candidate remediation technologies in combination with the scoring parameters and combined weights of the corresponding factors of each candidate remediation technology, and the preferred screening results of the contaminated site soil remediation technology are obtained. The specific steps are as follows:

S171: Based on the scores represented by the triangular fuzzy numbers of the corresponding factors of each candidate restoration technology, a restoration technology score matrix X is constructed, and the formula is:

Among them, x _ab = (x′ _ab , x″ _ab , x″′ _ab ), a=1,2,...,m; b=1,2,...,n;

S172: Construct the standardized matrix Z, the formula is:

Z＝( _zab ) _m×n

Among them, z _ab = (z′ _ab , z″ _ab , z″′ _ab )

For the income factors among the factors:

For cost factors among the factors:

S173: Calculate the addition ratio The formula is:

Among them, k is the number of benefit factors, and n-k is the number of cost factors;

S174: Sort the candidate repair technologies. The higher the number, the better.

In one embodiment of the present invention, the several indicators include technical indicators, economic indicators, environmental indicators and social indicators.

In one embodiment of the present invention, the factors affecting the technical indicators include operability, restoration effect, technology maturity and restoration time, the factors affecting the economic indicators include cost input and resource consumption, the factors affecting the environmental indicators include secondary pollution, and the factors affecting the social indicators include social acceptance, construction safety and restoration area interference, among which operability, restoration effect, technology maturity, social acceptance and construction safety are positive factors or benefit factors, and restoration time, cost input, resource consumption, secondary pollution and restoration area interference are negative factors or cost factors.

The above technical solution of the present invention has the following advantages compared with the prior art:

The evaluation method of the soil remediation technology of the contaminated site described in the present invention first screens the soil remediation technology of the contaminated site according to the MOORA method weighted by the combination of subjective weight and objective weight, and obtains the preferred screening result. It can comprehensively consider subjective factors such as experts and multiple objective factors affecting the soil remediation of the contaminated site, and can screen the soil pollution remediation technology from multiple angles, avoiding subjective bias and objective one-sidedness to a certain extent, and scientifically obtain the preferred screening result of the remediation technology; on the basis of the preferred screening result, the carbon footprint analysis is used to calculate the impact on the environment, so that the remediation technology can be made lower carbon, greener, and more sustainable in the remediation process, thereby meeting the requirements of environmental protection, and finally, the best evaluation result is obtained by the results of the preferred screening results and the carbon footprint analysis, and the overall advantages and disadvantages of the remediation technology can be judged in many aspects, and the best evaluation result of the remediation technology is more reliable. The screening method has a wide range of applications and is flexible to use. It can take into account the consideration of environmental protection requirements, which is conducive to the development of remediation work, and the best evaluation result of the remediation technology obtained is more scientific and reliable.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

FIG1 is a flow chart of an evaluation method for contaminated site soil remediation technology according to the present invention;

FIG2 is a specific flow chart of the evaluation method of the contaminated site soil remediation technology of the present invention;

3 is a model block diagram of the analytic hierarchy process in the evaluation method of the contaminated site soil remediation technology of the present invention;

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

1 to 3, the present invention provides a method for evaluating soil remediation technology for contaminated sites, comprising:

S1: The MOORA method, which combines subjective and objective weights, is used to screen soil remediation technologies for contaminated sites and obtain the optimal screening results;

S2: Carbon footprint analysis is performed on the top several restoration technologies in the preferred screening results, and they are ranked as follows:

S21: Calculate the carbon emissions C ₁ of material consumption using the formula:

Where f is the number of material types, CEA _t is the carbon emission factor of the t-th material, Q _t is the usage of the t-th material, and b _t is the recycling factor of the t-th material;

S22: Calculate the carbon emissions C ₂ from energy consumption using the formula:

Among them, V is the number of energy types, CEA _g is the carbon emission factor of the g-th energy, Q _g is the usage of the g-th energy, specifically, the carbon emission factors of electricity, gasoline and diesel are 0.884, 2.031 and 2.171 kgCO ₂ /kg respectively;

S23: Calculate the total carbon emissions CE of the restoration technology based on the carbon emissions _C1 of material consumption and the carbon emissions _C2 of energy consumption. The formula is:

CE＝C ₁ +C ₂

S24: Rank the top several restoration technologies in the preferred screening results according to the total carbon emissions CE, the smaller the total carbon emissions, the better;

S3: Combine the ranking of the optimal screening results with the ranking of the carbon footprint analysis to obtain the best evaluation results of the soil remediation technology for contaminated sites.

The evaluation method of soil remediation technology for contaminated sites first screens the soil remediation technology for contaminated sites according to the MOORA method weighted by the combination of subjective weight and objective weight, and obtains the optimal screening result. The MOORA method is a multi-objective optimization method, which is an existing method. It is scientific and objective, simple to calculate, and more flexible in practical application. It comprehensively considers subjective factors such as experts and multiple objective factors affecting soil remediation of contaminated sites, and can screen soil pollution remediation technology from multiple angles, avoiding subjective bias and objective one-sidedness to a certain extent, and scientifically obtains the optimal screening result of remediation technology; on the basis of the optimal screening result, the carbon footprint analysis is used to calculate the impact on the environment, which can make the remediation technology corresponding to the remediation process lower carbon, greener, and more sustainable, so as to meet the requirements of environmental protection. Finally, the optimal evaluation result is obtained by the optimal screening result and the carbon footprint analysis result, which can evaluate and judge the overall advantages and disadvantages of the remediation technology in many aspects, and the optimal evaluation result of the remediation technology is more reliable. The screening method has a wide range of applications and is flexible to use. It can take into account the consideration of environmental protection requirements, which is conducive to the development of remediation work, and the optimal evaluation result of the remediation technology obtained is more scientific and reliable.

Specifically, the MOORA method based on the combination of subjective weight and objective weight is used to screen the soil remediation technology for contaminated sites and obtain the optimal screening results. The specific steps are as follows:

S11: constructing a preliminary screening database for contaminated site soil remediation technologies, as shown in Table 1, inputting the types of pollutants in the contaminated site soil into the preliminary screening database, screening out several candidate remediation technologies, and obtaining the initial screening results;

Table 1 Preliminary screening database

In this embodiment, a preliminary screening database is constructed, and remediation technologies for various types of pollutants can be selected. It has a wide range of applications and good screening efficiency, and can save a lot of time and improve remediation efficiency.

S12: As shown in FIG3 , a screening index system is constructed using the hierarchical analysis method in the initial screening results. The screening index system includes a target layer, an index layer, a factor layer and a scheme layer. The target layer is to screen out the best evaluation results of the soil remediation technology for contaminated sites, the index layer includes several indicators, the factor layer includes several factors affecting the indicators, and the scheme layer is the alternative schemes for the soil remediation technology for contaminated sites;

S13: Input the subjective scoring parameters of each factor, and calculate the subjective weight of each factor through the hierarchical analysis method; the sources of determining the subjective scoring parameters of each factor include literature research, expert scoring and actual engineering cases. Based on multiple references, the subjective scoring is more valuable, the existing scoring is retrieved and input into the required formula, and the subjective weight of each factor is calculated;

S14: According to the candidate restoration technologies in the initial screening results, the scoring parameters of the factors corresponding to each candidate restoration technology are input, and the scoring parameters are expressed by triangular fuzzy numbers; due to the uncertainty of the expert or decision maker's scoring, the scoring parameters of the factors corresponding to each candidate restoration technology are introduced with triangular fuzzy numbers for fuzzy definition, which can effectively deal with the uncertainty of the factors, make up for the uncertainty factors generated by the subjective evaluation of the decision maker, enhance the closeness of the factor information to the actual situation, and thus make the evaluation results more scientific and reliable;

S15: Calculate the objective weight of the factor by using the entropy method according to the scoring parameters represented by the triangular fuzzy numbers of the factors corresponding to each candidate restoration technology;

S15: Combine the subjective weight and the objective weight, and assign weights to obtain the combined weight;

S16: Combined with the scoring parameters and combined weights of the corresponding factors of each candidate remediation technology, the MOORA method is used to calculate the addition ratio of the candidate remediation technology, and the ranking is used to obtain the preferred screening results of the soil remediation technology for contaminated sites.

In this embodiment, according to the operation of the restoration technology, several indicators include technical indicators, economic indicators, environmental indicators and social indicators. Specifically, the factors affecting the technical indicators include operability, restoration effect, technical maturity and restoration time, the factors affecting the economic indicators include cost input and resource consumption, the factors affecting the environmental indicators include secondary pollution, and the factors affecting the social indicators include social acceptance, construction safety and restoration area interference, among which operability, restoration effect, technical maturity, social acceptance and construction safety are positive factors or income factors, and the larger the value, the better. Restoration time, cost input, resource consumption, secondary pollution and restoration area interference are negative factors or cost factors, and the smaller the value, the better. Specifically, in the calculation of the entropy method in step S15, it is a positive factor and a negative factor, and in the calculation process of the MOORA method in step S17, it is a benefit factor and a cost factor. Taking into account environmental impact, economic rationality, social acceptance, technical feasibility and other factors, it is possible to screen soil pollution restoration technologies from multiple angles.

Furthermore, in step S3, the ranking of the preferred screening results and the ranking of the carbon footprint analysis are combined to calculate the final score using the weighted queuing scoring method. The specific steps are as follows:

S31: sorting the optimization screening results and the restoration technologies in the carbon footprint analysis according to their merits to obtain N ranking sequences, and taking the average of the rankings they should have occupied for the tied rankings;

S32: Calculate the individual score K _o of the oth restoration technology according to the ranking of the restoration technology, and the formula is:

Among them, v is the ranking number, the first place is 100 points, the last place is 60 points, and the middle score is between 60-100;

S33: Weight the individual scores and calculate the total score K, where _Lo is the weight of the repair technology, and the formula is:

S34: Sort by the total score K to determine the quality. The higher the score, the better. The best evaluation result of soil remediation technology for contaminated sites is obtained.

Specifically, in step S13, the subjective weight of each indicator is calculated by the hierarchical analysis method, and the calculation steps are as follows:

S131: Assume that there are n factors. According to the scale table, as shown in Table 2, the relative importance of each factor is determined by comparing them two by two. _aij represents the ratio of the influence of factor B _i and factor B _j on target A. A pairwise comparison judgment matrix A is constructed. The judgment matrix table is shown in Table 3.

Table 2 Scale table

Table 3 Judgment matrix

Where, i＝1,2,...,n; j＝＝1,2,...,n;

S132: Use the root-finding method to calculate the approximate value w _i of the eigenvector of the judgment matrix. The formula is:

After standardizing the feature vector, we get the subjective weight vector w, which is:

w＝(w ₁ ,w ₂ ,…, _wn ) ^T

S133: Calculate the consistency index CI, the formula is:

in,

Introducing random consistency ratio CR

Among them, the values of RI are shown in Table 4;

Table 4 RI values

n 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ... RI 0 0 0.52 0.89 1.12 1.26 1.36 1.41 1.46 1.49 1.52 1.54 1.56 1.58 1.59 ...

When the consistency ratio CR is less than the threshold, the subjective weight is correct and reasonable. When CR is greater than or equal to the threshold, the subjective weight is incorrect and unreasonable. The subjective scoring parameters and judgment matrix of each indicator are readjusted, and steps S121, S122 and S123 are repeated until the consistency ratio CR is less than the threshold.

Specifically, the threshold value may be 0.1.

Furthermore, in step S14, the scoring parameters of the corresponding factors of each candidate restoration technology are determined to obtain a scoring parameter table, as shown in Table 5, and the scoring parameters are expressed by triangular fuzzy numbers. After being expressed by triangular fuzzy numbers, the uncertainty factors generated by the subjective evaluation of the decision maker can be compensated, the actual closeness can be enhanced, and the evaluation results can be more scientific and reliable. The conversion relationship between the evaluation language and the triangular fuzzy number is shown in Table 6;

Table 5 Scoring parameters

Evaluation object Factor 1 Factor 2 ... Factor n 1 r ₁₁ r ₁₂ ... _1n 2 r ₂₁ r ₂₂ ... _2n ... ... ... ₁ ... m r _m1 r _m2 ... 1 _mn

Table 6 Transformation relationship between evaluation language and triangular fuzzy number

Furthermore, in step S15, the objective weight of the factor is calculated by the entropy method according to the scoring parameters represented by the triangular fuzzy numbers of the factors corresponding to each candidate restoration technology, and the calculation steps are as follows:

S151: Assume that the evaluation matrix X is composed of m alternative remediation technologies for contaminated site soil and the original data of n factors, and the formula is:

Wherein, a＝1,2,...,m；b＝1,2,...,n；

S152: Defuzzify the triangular fuzzy number and convert it into a definite value. The conversion formula is as follows:

S153: Each factor is normalized according to the number of each option to obtain a normalized matrix R, the formula is:

R＝( _r′ab ) _m×n

For the positive factors among the factors:

For negative factors:

S154: Calculate the proportion p _ab of the ath candidate repair technology factor value under the bth factor, and the formula is:

S155: Calculate the entropy value e _b of the b-th factor, the formula is:

in,

S156: Calculate the information entropy redundancy d _b , the formula is:

_db = 1- _eb

S157: Calculate the objective weight u _b of each factor, the formula is:

In this embodiment, in step S16, the subjective weight and the objective weight are combined and weighted according to the weight ratio h[w _j , _ub ]={0.5, 0.5} to obtain the combined weight h _j , which is:

h _j =0.5×w _j +0.5× _ub .

Furthermore, in step S17, the MOORA method (multi-objective optimization method) is used to calculate and sort the candidate remediation technologies in combination with the scoring parameters and combined weights of the corresponding factors of each candidate remediation technology, and the preferred screening results of the soil remediation technology for the contaminated site are obtained. The MOORA method is scientific and objective, simple to calculate, and more flexible in practical application. The scoring parameters are also expressed by triangular fuzzy numbers, which is more scientific and reliable. The specific steps are as follows:

S171: Based on the scores represented by the triangular fuzzy numbers of the corresponding factors of each candidate restoration technology, a restoration technology score matrix X is constructed, and the formula is:

Among them, x _ab = (x′ _ab , x″ _ab , x″′ _ab ), a=1,2,...,m; b=1,2,...,n;

S172: Construct the standardized matrix Z, the formula is:

Z＝( _zab ) _m×n

Among them, z _ab = (z′ _ab , z″ _ab , z″′ _ab )

For the income factors among the factors:

For cost factors among the factors:

S173: Calculate the addition ratio The formula is:

Among them, k is the number of benefit factors, and n-k is the number of cost factors;

S174: Sort the candidate repair technologies. The higher the number, the better.

As shown in Figure 2, this method first inputs the pollutant types into the constructed preliminary screening database, which can screen many remediation technologies for the first time and obtain several alternative remediation technologies, thereby improving the screening efficiency and saving a lot of time; then the hierarchical analysis method is used to construct a screening index system, which can comprehensively consider multiple indicators and multiple factors affecting the indicators, and can screen the soil remediation technology of contaminated sites from multiple angles. Then, the hierarchical analysis method and the entropy value method are combined to give weights, and the scoring parameters of the corresponding factors of each alternative remediation technology are expressed by triangular fuzzy numbers, which can effectively deal with the uncertainty of the factors and make up for the uncertainty factors caused by the subjective evaluation of decision makers, making the evaluation results more scientific and reliable. At the same time, the combined weights of the combined weighting can avoid the bias of subjective weighting and the one-sidedness of objective weighting to a certain extent. Then, the MOORA method is used to sort the alternative remediation technologies, and the optimal screening results of the remediation technologies are scientifically obtained. On the basis of the optimal screening results, the carbon footprint analysis is used to calculate the impact on the environment, which can make the remediation technology corresponding to the remediation process lower carbon and more sustainable. Finally, the queuing scoring method is used to evaluate the optimal remediation technology based on the optimal screening results and the results of the carbon footprint analysis, which can more conveniently judge the overall advantages and disadvantages of the remediation technology, and the optimal remediation technology obtained is more reliable. This screening method has a wide range of applications, is flexible to use, can take environmental considerations into account, has high screening efficiency, is conducive to the development of restoration work, saves a lot of time, and the best restoration technology obtained through evaluation is more scientific and reliable.

For example, in a company factory in a northern city in China, due to leakage in the chrome plating workshop, the soil in the factory was contaminated by heavy metal chromium.

Step 1: Input the pollutant type - heavy metals into the database, conduct a preliminary screening of the remediation technology, screen out the candidate remediation technologies, and obtain the initial screening results, including: in-situ electrokinetic separation, in-situ soil leaching, in-situ solidification/stabilization, in-situ vitrification, ex-situ chemical reduction/oxidation, ex-situ solidification/stabilization;

Step 2: Use the analytic hierarchy process to construct a screening index system for soil remediation technology for contaminated sites, as shown in Figure 3;

Among them: the screening index system is divided into four levels from high to low: target level A, index level B, factor level C and solution level D.

Indicator layer B1 is used to reflect technical factors, and its factor layer includes the following specific factors:

Operability C1, repair effect C2, technical maturity C3, repair time C4;

The indicator layer _B2 is used to reflect economic factors, and its factor layer includes the following specific factors:

Cost input C ₅ , resource consumption C ₆ ;

The indicator layer B ₃ is used to reflect environmental factors, and its factor layer includes the following specific factors:

Secondary pollution C ₇ ;

Indicator layer B ₄ is used to reflect social factors, and its factor layer includes the following specific factors:

social acceptance C ₈ , construction safety C ₉ , and disturbance in the restoration area C ₁₀ ;

Among them: operability _C1 , restoration effect _C2 , technical maturity _C3 , social acceptance _C8 , and construction safety _C9 are positive factors or benefit factors, and the larger the value, the better; restoration time _C4 , cost input _C5 , resource consumption _C6 , secondary pollution _C7 , and restoration area interference _C10 are negative factors or cost factors, and the smaller the value, the better.

Step 3: According to expert opinions, etc., the subjective scoring parameters of the factors are input into the corresponding database, and the subjective weights of the screening factors are calculated through the hierarchical analysis method;

(1) Construct a pairwise comparison judgment matrix,

Establish a judgment matrix table, as shown in Table 7:

Table 7 Judgment matrix

(2) Calculate the subjective weights. The results are shown in Table 8.

Table 8 Subjective weights

(3)Consistency test

The calculation shows that the maximum characteristic root λ _max is 10.950, CI = 0.11, RI = 1.49, CR = CI/RI = 0.074 < 0.1. Through a one-time test, it is judged that the matrix meets the consistency requirements.

Step 4: According to expert opinions and relevant information, the scoring parameters of the restoration technology are input into the corresponding database, and the scoring parameters are expressed by triangular fuzzy numbers. The scoring table of the restoration technology is shown in Table 9.

Table 9 Scoring table for repair technology

Step 5: Combined with the scores of the repair technology in step 4, the objective weights of the screening factors are calculated by the entropy method. The results are shown in Table 10;

Table 10 Objective weights

Step 6: Combine the subjective weight in step 3 and the objective weight in step 5 at a weight ratio of 0.5:0.5 to obtain the combined weight. The results are shown in Table 11.

Table 11 Combination weight table

Step 7: The MOORA method is used to combine the score of the remediation technology in step 4 and the combined weight of step 6 to calculate and rank the contaminated site soil remediation technology, and the preferred screening results of the contaminated site soil remediation technology are obtained. The results are shown in Table 12;

Table 12 Optimal screening results

Step 8: Carbon footprint analysis and ranking of the top three restoration technologies in the MOORA method are performed, and the results are shown in Table 13;

Table 13 Ranking after carbon footprint analysis

Step 9: The final score is calculated using the weighted queuing scoring method, and the weighting is performed at a weight ratio of 0.5:0.5 to obtain the best evaluation results of soil remediation technology for contaminated sites. The results are shown in Table 14;

Table 14 Best evaluation results of repair techniques

It can be seen from Table 14 that the comprehensive ranking of applicability after the evaluation of remediation technologies is as follows: ex situ chemical reduction/oxidation > in situ solidification/stabilization > in situ soil leaching.

Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims (10)

1. An evaluation method of soil remediation technology for contaminated sites, characterized in that it comprises: S1: According to the MOORA method of subjective weight and objective weight combined weighting, the soil remediation technology of the contaminated site is screened, and the optimal screening result is obtained; S2: The carbon footprint analysis and ranking of the top several repair technologies in the preferred screening results are as follows: S21: Calculate the carbon emission C ₁ of material consumption, the formula is: Among them, f is the number of material types, CEA _t is the carbon emission factor of the t-th material, Q _t is the usage amount of the t-th material, and b _t is the recycling factor of the t-th material; S22: Calculate the carbon emission C ₂ of energy consumption, the formula is: Among them, V is the number of energy types, CEA _g is the carbon emission factor of the g-th energy, and Q _g is the consumption of the g-th energy; S23: According to the carbon emission C ₁ of material consumption and the carbon emission C ₂ of energy consumption, calculate the total carbon emission CE of restoration technology, the formula is: CE＝C ₁ +C ₂ S24: According to the total carbon emission CE, sort the restoration technologies that are in the top rankings in the preferred screening results, the smaller the total carbon emission, the better; S3: Combining the ranking of the optimal screening results and the ranking of the carbon footprint analysis, the best evaluation result of the soil remediation technology of the contaminated site is obtained. 2. The evaluation method of soil remediation technology of polluted site according to claim 1, characterized in that: the MOORA method of combining weights according to subjective weight and objective weight screens soil remediation technology of polluted site, and obtains the optimal screening As a result, the specific steps are as follows: S11: Construct a primary screening database of soil remediation technologies for contaminated sites, input the types of pollutants in the contaminated site soil into the primary screening database, screen out a number of alternative remediation technologies, and obtain the primary screening results; S12: In the initial screening results, use the AHP to construct a screening index system. The screening index system includes a target layer, an index layer, a factor layer, and a program layer. The best evaluation result, the index layer includes several indicators, the factor layer includes some factors that affect the index, and the program layer is an alternative plan for the soil remediation technology of the polluted site; S13: Input the subjective scoring parameters of each factor, and calculate the subjective weight of each factor through the analytic hierarchy process; S14: According to the alternative restoration techniques in the initial screening results, input the scoring parameters of the corresponding factors of each alternative restoration technique, and express the scoring parameters with triangular fuzzy numbers; S15: According to the scoring parameters represented by the triangular fuzzy numbers of the corresponding factors of each alternative restoration technology, the objective weight of the factors is calculated by the entropy method; S16: Combining subjective weights and objective weights, combined weighting to obtain combined weights; S17: Combining the scoring parameters and combined weights of the corresponding factors of each alternative remediation technology, calculate the additive ratio for the alternative remediation technologies, and sort them to obtain the optimal screening results of soil remediation technologies for contaminated sites. 3. The evaluation method of soil remediation technology for contaminated sites according to claim 2, characterized in that: in the step S3, in combination with the sorting of the optimal screening results and the sorting of the carbon footprint analysis, the weighted queuing scoring method is used to calculate the final Scoring, the specific steps are as follows: S31: Arrange the optimal screening results and the restoration technologies in the carbon footprint analysis according to their advantages and disadvantages to obtain N ranking sequences, and take the average value of the rankings they should have occupied for the tied rankings; S32: Calculate the individual score K _o of the o-th restoration technology according to the ranking of the restoration technology, the formula is: Among them, v is the number of ranking names; S33: Weighting the individual scores to calculate the total score K, L _o is the weight of the restoration technique, the formula is: S34: Sorting according to the size of the total score K to determine the advantages and disadvantages, the higher the score, the better, and obtain the best evaluation result of the soil remediation technology of the contaminated site. 4. the assessment method of contaminated site soil remediation technology according to claim 2, is characterized in that: in step S13, calculates the subjective weight of each factor by analytic hierarchy process, and its calculation steps are as follows: S131: There are n factors, according to the scale table, pairwise comparison to determine the relative importance of each factor, a _ij represents the ratio of the influence degree of element B _i and element B _j on the target A, construct pairwise comparison judgment Matrix A, the formula is: Among them, i=1,2,...,n; j==1,2,...,n; S132: Calculate the approximate value w _i of the eigenvector of the judgment matrix by the root-finding method, the formula is: After standardizing the eigenvectors, the subjective weight vector w is obtained, and the formula is: w＝(w ₁ ,w ₂ ,…,w _n ) ^T S133: Calculate the consistency factor CI, the formula is: in, Introducing randomness consistency ratio CR When the consistency ratio CR is less than the threshold, the subjective weight is correct and reasonable; when the consistency ratio CR is greater than or equal to the threshold, the subjective weight is incorrect and unreasonable, readjust the subjective scoring parameters and judgment matrix of each factor , repeat steps S121, S122 and S123 until the consistency ratio CR is less than the threshold. 5. The evaluation method of soil remediation technology for contaminated sites according to claim 2, characterized in that: in step S14, according to the alternative remediation technologies in the initial screening results, input the scoring parameters of the corresponding factors of each alternative remediation technology, and The scoring parameters are represented by triangular fuzzy numbers, specifically: x _ab = (x′ _ab , x″ _ab , x″′ _ab ) Wherein, x ' _ab is the lower bound of triangular fuzzy number, is the most conservative estimated value; x " _ab is the most likely estimated value; x "' _ab is the upper bound of triangular fuzzy number, is the most optimistic estimated value, a= 1,2,...,m; b=1,2,...,n. 6. The evaluation method of soil remediation technology for contaminated sites according to claim 5, characterized in that: in step S15, according to the scoring parameters represented by the triangular fuzzy numbers of the corresponding factors of each alternative remediation technology, the objective value of the factors is calculated by the entropy method. Weight, the calculation steps are as follows: S151: Assume that the evaluation matrix X is composed of m alternative remediation technologies for contaminated site soil and the original data of n factors. The formula is: Among them, a=1,2,...,m; b=1,2,...,n; S152: Defuzzify the triangular fuzzy number and convert it into a definite value, the conversion formula is as follows: S153: Perform normalization processing on each factor according to the quantity of each option to obtain a normalized matrix R, the formula is: R=(r′ _ab ) _m×n For positive factors in factors: For negative factors in factors: S154: Calculate the proportion p _ab of the value of the a-th alternative restoration technology factor under the b-th factor, the formula is: S155: Calculate the entropy value e _b of the b-th factor, the formula is: in, S156: Calculate information entropy redundancy d _b , the formula is: d _b =1-e _b S157: Calculate the objective weight u _b of each factor, the formula is: 7. The evaluation method of soil remediation technology for contaminated sites according to claim 2, characterized in that: in step S16, the subjective weight w _j and the objective weight u _b are combined, according to h[w _j , u _b ]={0.5,0.5 }Weight ratio combined weighting to obtain the combined weight h _j , the formula is: h _j =0.5×w _j +0.5×u _b . 8. The evaluation method of soil remediation technology for contaminated sites according to claim 2, characterized in that: in step S17, in combination with the scoring parameters and combined weights of the corresponding factors of each alternative remediation technology, the alternative remediation technology is calculated using the MOORA method and sorting to obtain the optimal screening results of soil remediation technology for contaminated sites, the specific steps are as follows: S171: According to the score represented by the triangular fuzzy number of the corresponding factors of each alternative repair technology, construct the score matrix X of the repair technology, the formula is: Wherein, x _ab =(x′ _ab , x″ _ab , x″′ _ab ), a=1,2,...,m; b=1,2,...,n; S172: Construct a standardized matrix Z, the formula is: Z＝(z _ab ) _m×n Among them, z _ab = (z′ _ab , z″ _ab , z″′ _ab ) For the income factor in the factor: For cost-type factors in factors: S173: Calculate additive ratio The formula is: Among them, k is the number of income-type factors, and n-k is the number of cost-type factors; S174: Rank the alternative repair techniques, The higher the value, the better. 9. The evaluation method of soil remediation technology for contaminated sites according to claim 2, characterized in that: said several indicators include technical indicators, economic indicators, environmental indicators and social indicators. 10. The evaluation method of soil remediation technology for contaminated sites according to claim 9, characterized in that: the factors affecting the technical indicators include operability, repair effect, technical maturity and repair time, and the factors affecting the economic indicators Factors include cost input and resource consumption. Factors affecting the environmental indicators include secondary pollution. Factors affecting the social indicators include social acceptance, construction safety, and interference with restoration areas. Among them, operability, restoration effects, and technology maturity , social acceptance, and construction safety are positive factors or income-type factors, and restoration time, cost input, resource consumption, secondary pollution, and interference in the restoration area are negative factors or cost-type factors.