CN117066257A - Repairing method for chlorinated hydrocarbon polluted site - Google Patents
Repairing method for chlorinated hydrocarbon polluted site Download PDFInfo
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- CN117066257A CN117066257A CN202310052349.9A CN202310052349A CN117066257A CN 117066257 A CN117066257 A CN 117066257A CN 202310052349 A CN202310052349 A CN 202310052349A CN 117066257 A CN117066257 A CN 117066257A
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- chlorinated hydrocarbon
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- 150000008280 chlorinated hydrocarbons Chemical class 0.000 title claims abstract description 109
- 238000000034 method Methods 0.000 title claims abstract description 44
- 239000002689 soil Substances 0.000 claims abstract description 80
- 238000000605 extraction Methods 0.000 claims abstract description 72
- 239000003344 environmental pollutant Substances 0.000 claims abstract description 60
- 231100000719 pollutant Toxicity 0.000 claims abstract description 60
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 56
- 230000001590 oxidative effect Effects 0.000 claims abstract description 25
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 24
- 239000007800 oxidant agent Chemical class 0.000 claims abstract description 23
- 230000003647 oxidation Effects 0.000 claims abstract description 23
- 239000003513 alkali Substances 0.000 claims abstract description 19
- 238000005496 tempering Methods 0.000 claims abstract description 11
- 239000000126 substance Substances 0.000 claims abstract description 10
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 9
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 9
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 9
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 9
- 238000011065 in-situ storage Methods 0.000 claims abstract description 9
- 230000008439 repair process Effects 0.000 claims abstract description 7
- 238000010525 oxidative degradation reaction Methods 0.000 claims abstract description 5
- 239000012808 vapor phase Substances 0.000 claims abstract description 3
- UOCLXMDMGBRAIB-UHFFFAOYSA-N 1,1,1-trichloroethane Chemical compound CC(Cl)(Cl)Cl UOCLXMDMGBRAIB-UHFFFAOYSA-N 0.000 claims description 32
- 238000002347 injection Methods 0.000 claims description 28
- 239000007924 injection Substances 0.000 claims description 28
- 239000003673 groundwater Substances 0.000 claims description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims description 15
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 13
- 238000006243 chemical reaction Methods 0.000 claims description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 10
- 239000001301 oxygen Substances 0.000 claims description 10
- 229910052760 oxygen Inorganic materials 0.000 claims description 10
- 230000001737 promoting effect Effects 0.000 claims description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 3
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 3
- 159000000001 potassium salts Chemical class 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 239000012071 phase Substances 0.000 claims description 2
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 description 27
- LGXVIGDEPROXKC-UHFFFAOYSA-N 1,1-dichloroethene Chemical group ClC(Cl)=C LGXVIGDEPROXKC-UHFFFAOYSA-N 0.000 description 27
- 239000000243 solution Substances 0.000 description 13
- 238000005457 optimization Methods 0.000 description 12
- 238000006722 reduction reaction Methods 0.000 description 9
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 description 7
- 238000006298 dechlorination reaction Methods 0.000 description 7
- -1 persulfate ions Chemical class 0.000 description 7
- 239000012286 potassium permanganate Substances 0.000 description 7
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 7
- 238000006731 degradation reaction Methods 0.000 description 6
- 239000012670 alkaline solution Substances 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 238000005070 sampling Methods 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 239000013067 intermediate product Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000001603 reducing effect Effects 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000000370 acceptor Substances 0.000 description 2
- HRYZWHHZPQKTII-UHFFFAOYSA-N chloroethane Chemical compound CCCl HRYZWHHZPQKTII-UHFFFAOYSA-N 0.000 description 2
- 239000012459 cleaning agent Substances 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 229960003750 ethyl chloride Drugs 0.000 description 2
- 239000002957 persistent organic pollutant Substances 0.000 description 2
- 238000005067 remediation Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 description 1
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000006065 biodegradation reaction Methods 0.000 description 1
- 238000010170 biological method Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000006652 catabolic pathway Effects 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 125000001309 chloro group Chemical group Cl* 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000007857 degradation product Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000004434 industrial solvent Substances 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229950011008 tetrachloroethylene Drugs 0.000 description 1
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/002—Reclamation of contaminated soil involving in-situ ground water treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/06—Reclamation of contaminated soil thermally
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C2101/00—In situ
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Soil Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
A method for repairing a chlorinated hydrocarbon polluted site sequentially carries out staged repair on the chlorinated hydrocarbon polluted site by utilizing vapor extraction, in-situ chemical oxidation and heat-enhanced extraction; firstly, removing most volatile and semi-volatile pollutants in soil by adopting an extraction method; secondly, in-situ chemical oxidation is adopted, alkali liquor is injected into soil and underground water, primary oxidation is carried out on chlorinated hydrocarbon pollutants, hydrolysis reaction of the pollutants is promoted to decompose and convert low-substituted hydrocarbon, oxidant is injected into the soil and underground water, secondary oxidation is carried out on the chlorinated hydrocarbon pollutants, and oxidative degradation of the chlorinated hydrocarbon pollutants is promoted; finally, hot intensified extraction is adopted, hot air is injected into the soil and the underground water, and a vapor phase extraction device is started to perform hot intensified extraction operation. The characteristics of pollutants are fully utilized, and the chlorinated hydrocarbon pollution site is sequentially repaired in stages by utilizing vapor extraction, in-situ chemical oxidation and heat strengthening extraction, so that the efficient removal of chlorinated hydrocarbon pollutants is realized.
Description
Technical Field
The invention relates to the technical field of polluted soil and groundwater remediation, in particular to a method for remediating chlorinated hydrocarbon polluted sites.
Background
Chlorinated hydrocarbons are organic compounds in which one or more hydrogen atoms in aliphatic hydrocarbons, aromatic hydrocarbons and derivatives thereof are replaced with chlorine atoms, are volatile organic contaminants, are poorly soluble in water, have strong mobility in aquifers, have strong vertical mobility in groundwater due to the relative density of most chlorinated hydrocarbons being greater than 1, and are prone to forming heavy non-aqueous liquids (DNAPL) on aquifers. The slow release of DNAPL into groundwater after formation, especially in hydrogeology complex situations, can increase groundwater remediation difficulties and costs. As an efficient industrial solvent and cleaning agent, the water-based cleaning agent is widely applied to the industries of chemical industry, machinery, electronics, leather and the like, and soil and groundwater can be polluted due to improper use or treatment. The pollutants have the characteristics of high toxicity, high enrichment and high environmental residue, are generally difficult to degrade naturally, have long residue time in soil and water bodies and three-induced effects, and belong to persistent organic pollutants, wherein most of the pollutants are organic pollutants which are listed as priority control by various countries.
In the prior art, the repairing method of chlorinated hydrocarbon pollution mainly comprises a physical method, a biological method, a chemical method and the like, and the standard repairing of the polluted site is generally difficult to be realized by a single or universal method due to the complex condition of the polluted site, and most repairing processes at present have the problems of low repairing efficiency, long repairing period and the like.
Disclosure of Invention
The invention aims to solve the technical problems and provide a repairing method for a chlorinated hydrocarbon polluted site, which fully utilizes the characteristics of pollutants, and repairs the polluted site by stages by combining different repairing technologies so as to realize the efficient removal of chlorinated hydrocarbon pollutants.
The invention solves the technical problems, and adopts the following technical scheme: a method for repairing a chlorinated hydrocarbon polluted site sequentially carries out staged repair on the chlorinated hydrocarbon polluted site by utilizing vapor extraction, in-situ chemical oxidation and heat-enhanced extraction; firstly, removing most volatile and semi-volatile pollutants in soil by adopting an extraction method; secondly, in-situ chemical oxidation is adopted, alkali liquor is injected into soil and underground water, primary oxidation is carried out on chlorinated hydrocarbon pollutants, hydrolysis reaction of the pollutants is promoted to decompose and convert low-substituted hydrocarbon, oxidant is injected into the soil and underground water, secondary oxidation is carried out on the chlorinated hydrocarbon pollutants, and oxidative degradation of the chlorinated hydrocarbon pollutants is promoted; and finally, adopting heat strengthening extraction, namely injecting hot air into the soil and the underground water, starting a vapor phase extraction device, performing heat strengthening extraction operation, promoting the removal of residual chlorinated hydrocarbon pollutants, and simultaneously increasing the oxygen concentration in the soil and the underground water to promote the aerobic reaction.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the method comprises the following steps:
1) Extracting soil in a polluted site by starting a vapor extraction device to remove most volatile and semi-volatile chlorinated hydrocarbon pollutants in the soil;
2) After the vapor extraction is finished, alkaline liquor is injected into soil and underground water to carry out primary oxidation on chlorinated hydrocarbon pollutants, so that the pollutants are promoted to be subjected to hydrolysis reaction to decompose and convert the low-substituted hydrocarbon;
3) Then, injecting an oxidant into the soil and the groundwater to perform secondary oxidation on chlorinated hydrocarbon pollutants, so as to promote the oxidative degradation of the chlorinated hydrocarbon pollutants;
4) And finally, injecting hot air into the soil and the underground water, starting a vapor extraction device, performing heat strengthening extraction operation, promoting the removal of residual chlorinated hydrocarbon pollutants, and simultaneously increasing the oxygen concentration in the soil and the underground water to promote the generation of aerobic reaction.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the chlorinated hydrocarbon polluted site is a polluted site with the concentration of chlorinated hydrocarbon in soil being less than 8000mg/kg, the concentration of chlorinated hydrocarbon in groundwater being less than 10mg/L and the Henry constant of chlorinated hydrocarbon being more than 4atm L/mol.
As a further optimization of the method for repairing a chlorinated hydrocarbon polluted site, the chlorinated hydrocarbon pollutant is at least one of 1, 1-trichloroethane, 1-dichloroethane, 1-dichloroethylene and vinyl chloride.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the polluted site is provided with an extraction well for extracting by a gas phase extraction device and an injection well for injecting alkali liquor, oxidant and hot air into soil and underground water.
As a further optimization of the method for repairing the chlorinated hydrocarbon polluted site, the extraction in the step 1) is intermittent extraction.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the temperature of the hot air is 30-150 ℃.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the concentration of the alkali liquor is 10-35%.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the alkali liquor is one or two of sodium hydroxide and potassium hydroxide.
As a further optimization of the method for repairing the chlorinated hydrocarbon polluted site, the oxidant is one or two of persulfates and permanganates.
As a further optimization of the method for repairing the chlorinated hydrocarbon polluted site, persulfate and permanganate are sodium salts or potassium salts.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the concentration of the persulfate is 15-35%, and the concentration of the permanganate is 1-10%.
As a further optimization of the repairing method of the chlorinated hydrocarbon polluted site, the concentration of the persulfate is 20-30%, and the concentration of the permanganate is 2-6%.
The invention has the following beneficial effects:
according to the method, most pollutants are removed through an extraction method according to the characteristic of strong volatility of chlorinated hydrocarbon pollutants, alkali liquor with a certain concentration is injected into soil and underground water according to the characteristic of a chlorinated hydrocarbon pollutant volatilizing chlorine reaction, primary oxidation is carried out on the chlorinated hydrocarbon pollutants, hydrolysis reaction is promoted to generate low-substituted hydrocarbon decomposition and conversion, persulfate and permanganate with higher oxidizing property are injected into the soil and the underground water after a period of time is separated, further reduction and degradation of low-chlorinated intermediate products are promoted, and finally hot air is introduced into the soil and the underground water through an injection well for carrying out heat strengthening extraction operation, so that residual chlorinated hydrocarbon can be continuously removed, the oxygen concentration in the soil and the underground water can be increased to promote aerobic reaction, and meanwhile, residual persulfate ions in the soil and the underground water are activated by utilizing heat to convert the persulfate radicals to promote sulfate reduction reaction, so that the complete removal of the pollutants is realized.
Drawings
FIG. 1 is a flow chart of a repair process of the repair method of the present invention;
FIG. 2 is a schematic diagram of the degradation pathways of 1, 1-trichloroethane.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
As shown in figure 1, the invention provides a repairing method for a chlorinated hydrocarbon polluted site, which sequentially repairs the chlorinated hydrocarbon polluted site in stages by utilizing vapor extraction, in-situ chemical oxidation and heat-enhanced extraction, so as to eliminate chlorinated hydrocarbon pollutants. The chlorinated hydrocarbon pollution site in the invention refers to a pollution site with the concentration of chlorinated hydrocarbon in soil being less than 8000mg/kg, the concentration of chlorinated hydrocarbon in groundwater being less than 10mg/L and the Henry constant of chlorinated hydrocarbon being more than 4atm L/mol. The chlorinated hydrocarbon contaminant is at least one of 1, 1-trichloroethane, 1-dichloroethane, 1-dichloroethylene and vinyl chloride.
The repairing method of the chlorinated hydrocarbon polluted site comprises the following steps:
1) Arranging an extraction well, an injection well and a vapor extraction device in a pollution site; the vapor extraction device is a prior art device; because the organic matters such as 1, 1-trichloroethane, 1-dichloroethane, 1-dichloroethylene and chloroethane in the polluted soil have higher Henry constants, for example, the Henry constant of 1, 1-trichloroethane is 14.4atm L/mol, the Henry constant of 1, 1-dichloroethylene is 34atm L/mol and the like, the partial pressure of the gas of the pollutants in the soil and underground water is relatively higher, the volatility is strong, the intermittent extraction is continuously carried out on the soil in the polluted field by starting the vapor extraction device, most volatile and semi-volatile chlorinated hydrocarbons in the soil can be pumped into the ground, and the subsequent gas-liquid separation, the oil-water separation, the waste gas adsorption and the like are carried out on the soil through a treatment system on the ground, so that most volatile and semi-volatile chlorinated hydrocarbon pollutants in the soil are removed;
2) After the vapor extraction is finished, alkaline liquid with the concentration of 10-35% is injected into soil and underground water through an injection well, wherein the alkaline liquid is one or two of sodium hydroxide and potassium hydroxide; the alkali liquor enables chlorinated hydrocarbon pollutants in soil and underground water to undergo hydrolysis reaction with strong alkali (RCl+sodium hydroxide-ROH+NaCl) to promote chlorinated hydrocarbon pollutants to remove one chloride ion, so that the chlorinated hydrocarbon pollutants undergo hydrolysis reaction to be decomposed and converted into low-substituted hydrocarbon, for example, 111-trichloroethane is very intractable and is difficult to oxidize, but the alkali liquor can promote a part of 111-trichloroethane to be converted into 1, 1-dichloroethane and 1, 1-dichloroethylene, so that the chlorinated hydrocarbon pollutants are decomposed and converted into low-substituted hydrocarbon, the subsequent oxidation difficulty of the chlorinated hydrocarbon pollutants is reduced, and the amount of the oxidant injected subsequently can be reduced;
3) After the alkali liquor is put into the soil and the groundwater for a period of time, oxidant is injected into the soil and the groundwater through an injection well, and chlorinated hydrocarbon pollutants are subjected to secondary oxidation, wherein the oxidant is one or two of persulfate and permanganate; persulfates and permanganates are sodium or potassium salts. The concentration of persulfate is 15-35%, and the concentration of permanganate is 1-10%. The optimal concentration of the persulfate is 20-30%, and the optimal concentration of the permanganate is 2-6%;
persulfate is a strong oxidant, can be activated by alkali liquor injected into soil and underground water in advance, so that chlorinated hydrocarbon multistage degradation products and derivatives are oxidized, and chlorinated hydrocarbon pollutants are promoted to be decomposed and converted into low-substituted hydrocarbon through hydrolysis reaction;
permanganate is a strong oxidant, can exist in polluted soil and underground water for a long time, continuously oxidizes and eliminates chlorinated hydrocarbon volatilized from a low permeability layer and chlorinated hydrocarbon generated by back diffusion, and can solve the problems of pollutant tailing and rebound commonly existing in the repairing process;
4) After the two-stage oxidation is completed for a period of time, injecting hot air at 30-150 ℃ into the soil and underground water, starting a vapor extraction device, performing soil and underground water heat strengthening extraction operation, wherein heat strengthening extraction can promote removal of residual chlorinated hydrocarbon pollutants and degradation derivatives thereof, a large amount of oxygen enters the polluted soil and underground water along with the injection of the hot air, increasing the oxygen concentration in the soil and the underground water to promote aerobic reaction, and simultaneously activating residual persulfate ions in the soil and the underground water at high temperature to convert the residual persulfate ions into sulfate radicals, so that a large amount of electron donors are provided for sulfate reduction reaction of chlorinated hydrocarbon, and anaerobic biodegradation of the pollutants in the soil and the underground water is promoted.
The staged restoration method provided by the invention fully utilizes the physical properties and reaction characteristics of chlorinated hydrocarbon pollutants, firstly removes most pollutants by an extraction method according to the characteristic of strong volatility, and then gradually oxidizes and removes the residual chlorinated hydrocarbon in soil and water body according to the reaction characteristic of chlorinated hydrocarbon. Researches show that the dechlorination reaction in the degradation process of chlorinated hydrocarbon is carried out step by step, the high chlorinated hydrocarbon has stronger oxidizing property than the low chlorinated hydrocarbon, the dechlorination reaction can be carried out in the environment with weaker reducing property, the low chlorinated hydrocarbon needs stronger reducing environment for further dechlorination, thus the high chlorinated hydrocarbon is easy to accumulate intermediate products under the reducing condition, such as tetrachloroethylene and trichloroethylene are easy to accumulate in the degradation process, the final complete dechlorination of the chlorinated hydrocarbon is easy to be realized if the subsequent environment is an aerobic environment, and the 1, 1-trichloroethane can be continuously reduced and dechlorinated to generate 1, 1-dichloroethane and chloroethane under the natural condition. According to the characteristics of the dechlorination reaction of chlorinated hydrocarbon, alkaline solution with a certain concentration is injected into soil and underground water after the extraction operation is finished, and is used as an oxidant to promote the reduction reaction of high-chlorinated pollutants, and persulfates and permanganates with higher oxidability are added after a period of time, so that the further reduction degradation of low-chlorinated intermediate products is promoted, and the final dechlorination is realized, thereby thoroughly eliminating the pollutants.
In addition, the dechlorination process can be divided into two paths of aerobic oxidation and anaerobic reduction according to the difference of electron acceptors existing in the environment. Under a certain oxidation-reduction potential, chlorinated hydrocarbon is subjected to sequential reduction degradation under the action of microorganisms, wherein sulfate reduction reaction and methanogenesis reaction are adopted to take advantage, SO that electron donors such as SO42-, fe3+, NO 3-and CO2 are added into soil and water, and chlorinated hydrocarbon is used as an electron acceptor to promote anaerobic reaction; oxygen is injected into the polluted soil and the water body, so that the concentration of the oxygen in the polluted soil and the water body is increased, and the aerobic oxidation reaction is promoted. According to the characteristics, hot air is introduced into the soil and the underground water through the injection well to perform heat-enhanced extraction operation, so that residual chlorinated hydrocarbon can be continuously removed, the oxygen concentration in the soil and the underground water can be increased to promote aerobic reaction, and meanwhile, residual persulfate ions in the soil and the underground water are activated by utilizing heat to be converted into sulfate radicals to promote sulfate reduction reaction and complete removal of pollutants.
The method for repairing the in-situ electrochemical circulating well of chlorinated hydrocarbon polluted groundwater provided by the invention is described in detail below with reference to examples.
Example 1
A chlorinated hydrocarbon contaminated site, field regulation results showed that the concentration of 1, 1-trichloroethane in the soil was at most 5820mg/kg, the concentration of 1, 1-dichloroethylene was at most 847mg/kg, the concentration of 1, 1-dichloroethane was at most 131mg/kg, the concentration of 1, 1-trichloroethane in groundwater was at most 1147. Mu.g/L, the concentration of 1, 1-dichloroethylene was at most 2863. Mu.g/L, and the concentration of 1, 1-dichloroethane was at most 435. Mu.g/L. Arranging an injection well and an extraction well according to site conditions, starting a vapor extraction device, intermittently extracting for 30 days at a vacuum degree of 20-40 kPa, and stopping the intermittent extraction, wherein the concentration of 1, 1-trichloroethane in the detected soil is 2761mg/kg, the concentration of 1, 1-dichloroethylene is 159mg/kg, and the concentration of 1, 1-dichloroethane is 28mg/kg; then, injecting an alkaline solution with the mass concentration of 22% into an injection well, wherein the alkaline solution is a sodium hydroxide solution, and continuously injecting an oxidant into the injection well after 40 days, wherein the oxidant is formed by mixing a sodium persulfate solution and a potassium permanganate solution, wherein the mass concentration of sodium persulfate is 25%, and the mass concentration of potassium permanganate is 5%; after 30 days of interval, hot air is injected into the injection well, the vapor extraction device is started, the temperature of the hot air is controlled at 90 ℃, and the intermittent operation is carried out for about 10 days. Sampling and detecting after half a year, wherein the concentration of 1, 1-trichloroethane in the soil is 573mg/kg, the concentration of 1, 1-dichloroethylene is 44mg/kg, and the concentration of 1, 1-dichloroethane is 6.9mg/kg, so that the standard values of two types of application GB36600 are reached; the concentration of 1, 1-trichloroethane in underground water is 86 mug/L, the concentration of 1, 1-dichloroethylene is 26 mug/L, the highest concentration of 1, 1-dichloroethane is 11 mug/L, and the requirements of GB14848 class III underground water are preliminarily met.
Example 2
A chlorinated hydrocarbon contaminated site, field regulation results showed that the concentration of 1, 1-trichloroethane in the soil was at most 3981mg/kg, the concentration of 1, 1-dichloroethylene was at most 645mg/kg, the concentration of 1, 1-dichloroethane was at most 110mg/kg, the concentration of 1, 1-trichloroethane in groundwater was at most 967. Mu.g/L, the concentration of 1, 1-dichloroethylene was at most 1863. Mu.g/L, and the concentration of 1, 1-dichloroethane was at most 331. Mu.g/L. Arranging an injection well and an extraction well according to site conditions, starting a vapor extraction device, intermittently extracting for 20 days at a vacuum degree of 20-40 kPa, and stopping the intermittent extraction, wherein the concentration of 1, 1-trichloroethane in the detected soil is 2100mg/kg, the concentration of 1, 1-dichloroethylene is 254mg/kg, and the concentration of 1, 1-dichloroethane is 38mg/kg; then, injecting 10% alkali liquor into the injection well, wherein the alkali liquor is formed by mixing sodium hydroxide solution and potassium hydroxide solution, and continuously injecting an oxidant into the injection well after 30 days, wherein the oxidant is formed by mixing sodium persulfate solution and potassium permanganate solution, wherein the mass concentration of sodium persulfate is 15%, and the mass concentration of potassium permanganate is 1%; after 20 days of interval, hot air is injected into the injection well, the vapor extraction device is started, the temperature of the hot air is controlled at 70 ℃, and the intermittent operation is carried out for about 10 days. Sampling and detecting after half a year, wherein the concentration of 1, 1-trichloroethane in the soil is 402mg/kg, the concentration of 1, 1-dichloroethylene is 36mg/kg, and the concentration of 1, 1-dichloroethane is 5.3mg/kg, so that the standard values of two types of application GB36600 are reached; the concentration of 1, 1-trichloroethane in underground water is 75 mug/L, the concentration of 1, 1-dichloroethylene is 16 mug/L, and the highest concentration of 1, 1-dichloroethane is 9 mug/L, thereby meeting the requirements of GB14848 class III underground water.
Example 3
A chlorinated hydrocarbon contaminated site, field regulation results showed that the concentration of 1, 1-trichloroethane in the soil was at most 7860mg/kg, the concentration of 1, 1-dichloroethylene was at most 1247mg/kg, the concentration of 1, 1-dichloroethane was at most 235mg/kg, the concentration of 1, 1-trichloroethane in groundwater was at most 1647. Mu.g/L, the concentration of 1, 1-dichloroethylene was at most 3463. Mu.g/L, and the concentration of 1, 1-dichloroethane was at most 575. Mu.g/L. Arranging an injection well and an extraction well according to site conditions, starting a vapor extraction device, intermittently extracting for 40 days at a vacuum degree of 30-60 kPa, and stopping the intermittent extraction, wherein the concentration of 1, 1-trichloroethane in the detected soil is 3311mg/kg, the concentration of 1, 1-dichloroethylene is 122mg/kg, and the concentration of 1, 1-dichloroethane is 520mg/kg; then, injecting alkaline solution with the mass concentration of 35% into an injection well, wherein the alkaline solution is formed by mixing sodium hydroxide solution and potassium hydroxide solution, and continuously injecting an oxidant into the injection well after 50 days, wherein the oxidant is formed by mixing sodium persulfate solution and potassium permanganate solution, wherein the mass concentration of sodium persulfate is 35%, and the mass concentration of potassium permanganate is 10%; after an interval of 40 days, hot air was injected into the injection well, the vapor extraction apparatus was started, the hot air temperature was controlled at 140 ℃, and the batch operation was performed for about 10 days. Sampling and detecting after half a year, wherein the concentration of 1, 1-trichloroethane in the soil is 671mg/kg, the concentration of 1, 1-dichloroethylene is 45mg/kg, and the concentration of 1, 1-dichloroethane is 8.1mg/kg, so that the standard values of two types of application GB36600 are reached; the concentration of 1, 1-trichloroethane in underground water is 110 mug/L, the concentration of 1, 1-dichloroethylene is 24 mug/L, and the highest concentration of 1, 1-dichloroethane is 13 mug/L, thereby meeting the requirements of GB14848 class III underground water.
Example 4
A chlorinated hydrocarbon contaminated site, field regulation results showed that the concentration of 1, 1-trichloroethane in the soil was at most 4870mg/kg, the concentration of 1, 1-dichloroethylene was at most 647mg/kg, the concentration of 1, 1-dichloroethane was at most 121mg/kg, the concentration of 1, 1-trichloroethane in groundwater was at most 1047. Mu.g/L, the concentration of 1, 1-dichloroethylene was at most 2363. Mu.g/L, and the concentration of 1, 1-dichloroethane was at most 375. Mu.g/L. Arranging an injection well and an extraction well according to site conditions, starting a vapor extraction device, intermittently extracting for 25 days at a vacuum degree of 20-40 kPa, and stopping the intermittent extraction, wherein the concentration of 1, 1-trichloroethane in the detected soil is 2761mg/kg, the concentration of 1, 1-dichloroethylene is 159mg/kg, and the concentration of 1, 1-dichloroethane is 28mg/kg; then, 10% alkali solution, namely potassium hydroxide solution, is injected into the injection well, and after 30 days, oxidant, namely 27% sodium persulfate, is continuously injected into the injection well; after 30 days of interval, hot air was injected into the injection well, the vapor extraction apparatus was started, the hot air temperature was controlled at 70 ℃, and the batch operation was performed for about 10 days. Sampling and detecting after half a year, wherein the concentration of 1, 1-trichloroethane in the soil is 543mg/kg, the concentration of 1, 1-dichloroethylene is 40mg/kg, and the concentration of 1, 1-dichloroethane is 6.5mg/kg, so that the standard values of two types of land used in GB36600 are reached; the concentration of 1, 1-trichloroethane in underground water is 82 mug/L, the concentration of 1, 1-dichloroethylene is 22 mug/L, the highest concentration of 1, 1-dichloroethane is 10 mug/L, and the requirements of GB14848 class III underground water are preliminarily met.
Example 5
A chlorinated hydrocarbon contaminated site, field regulation results show that the concentration of 1, 1-trichloroethane in the soil is at most 5029mg/kg, the concentration of 1, 1-dichloroethylene is at most 742mg/kg, the concentration of 1, 1-dichloroethane is at most 109mg/kg, the concentration of 1, 1-trichloroethane in groundwater is at most 947 mug/L, the concentration of 1, 1-dichloroethylene is at most 1803 mug/L, and the concentration of 1, 1-dichloroethane is at most 435 mug/L. Arranging an injection well and an extraction well according to site conditions, starting a vapor extraction device, intermittently extracting for 30 days at a vacuum degree of 20-40 kPa, and stopping the intermittent extraction, wherein the concentration of 1, 1-trichloroethane in the detected soil is 1761mg/kg, the concentration of 1, 1-dichloroethylene is 119mg/kg, and the concentration of 1, 1-dichloroethane is 38mg/kg; then, injecting 23% alkali solution, namely potassium hydroxide solution, into an injection well, and continuously injecting an oxidant, namely 7% potassium permanganate solution, into the injection well after 35 days; after 30 days of interval, hot air is injected into the injection well, the vapor extraction device is started, the temperature of the hot air is controlled at 110 ℃, and the intermittent operation is carried out for about 10 days. Sampling and detecting after half a year, wherein the concentration of 1, 1-trichloroethane in the soil is 573mg/kg, the concentration of 1, 1-dichloroethylene is 44mg/kg, and the concentration of 1, 1-dichloroethane is 6.9mg/kg, so that the standard values of two types of application GB36600 are reached; the concentration of 1, 1-trichloroethane in underground water is 86 mug/L, the concentration of 1, 1-dichloroethylene is 26 mug/L, the highest concentration of 1, 1-dichloroethane is 11 mug/L, and the requirements of GB14848 class III underground water are preliminarily met.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the claims without affecting the spirit of the invention.
Claims (13)
1. A repairing method of chlorinated hydrocarbon polluted site is characterized in that: sequentially carrying out staged repair on chlorinated hydrocarbon polluted sites by utilizing vapor extraction, in-situ chemical oxidation and heat strengthening extraction; firstly, removing most volatile and semi-volatile pollutants in soil by adopting an extraction method; secondly, in-situ chemical oxidation is adopted, alkali liquor is injected into soil and underground water, primary oxidation is carried out on chlorinated hydrocarbon pollutants, hydrolysis reaction of the pollutants is promoted to decompose and convert low-substituted hydrocarbon, oxidant is injected into the soil and underground water, secondary oxidation is carried out on the chlorinated hydrocarbon pollutants, and oxidative degradation of the chlorinated hydrocarbon pollutants is promoted; and finally, adopting heat strengthening extraction, namely injecting hot air into the soil and the underground water, starting a vapor phase extraction device, performing heat strengthening extraction operation, promoting the removal of residual chlorinated hydrocarbon pollutants, and simultaneously increasing the oxygen concentration in the soil and the underground water to promote the aerobic reaction.
2. A method for repairing a chlorinated hydrocarbon contaminated site according to claim 1, comprising the steps of: 1) Extracting soil in a polluted site by starting a vapor extraction device to remove most volatile and semi-volatile chlorinated hydrocarbon pollutants in the soil;
2) After the vapor extraction is finished, alkaline liquor is injected into soil and underground water to carry out primary oxidation on chlorinated hydrocarbon pollutants, so that the pollutants are promoted to be subjected to hydrolysis reaction to decompose and convert the low-substituted hydrocarbon;
3) Then, injecting an oxidant into the soil and the groundwater to perform secondary oxidation on chlorinated hydrocarbon pollutants so as to promote the oxidative degradation of the chlorinated hydrocarbon pollutants;
4) And finally, injecting hot air into the soil and the underground water, starting a vapor extraction device, performing heat strengthening extraction operation, promoting the removal of residual chlorinated hydrocarbon pollutants, and simultaneously increasing the oxygen concentration in the soil and the underground water to promote the generation of aerobic reaction.
3. A method for repairing a chlorohydrocarbon contaminated site according to claim 1, wherein: the chlorinated hydrocarbon pollution site is a pollution site with the concentration of chlorinated hydrocarbon in soil being less than 8000mg/kg, the concentration of chlorinated hydrocarbon in groundwater being less than 10mg/L and the Henry constant of chlorinated hydrocarbon being more than 4atm L/mol.
4. A method for repairing a chlorohydrocarbon contaminated site according to claim 1, wherein: the chlorinated hydrocarbon pollutant is at least one of 1, 1-trichloroethane, 1-dichloroethane, 1-dichloroethylene and vinyl chloride.
5. A method for repairing a chlorohydrocarbon contaminated site according to claim 2, wherein: the polluted site is provided with an extraction well for extracting by a gas phase extraction device and an injection well for injecting alkali liquor, oxidant and hot air into soil and groundwater.
6. A method for repairing a chlorohydrocarbon contaminated site according to claim 2, wherein: the extraction in the step 1) is batch extraction.
7. A method for repairing a chlorohydrocarbon contaminated site according to claim 2, wherein: the temperature of the hot air is 30-150 ℃.
8. A method for repairing a chlorohydrocarbon contaminated site according to claim 2, wherein: the concentration of the alkali liquor is 10-35%.
9. A method for repairing a chlorohydrocarbon contaminated site according to claim 2, wherein: the alkali liquor is one or two of sodium hydroxide and potassium hydroxide.
10. A method for repairing a chlorohydrocarbon contaminated site according to claim 2, wherein: the oxidant is one or two of persulfate and permanganate.
11. A method for repairing a chlorinated hydrocarbon contaminated site according to claim 10, wherein: persulfates and permanganates are sodium or potassium salts.
12. A method for repairing a chlorinated hydrocarbon contaminated site according to claim 10, wherein: the concentration of persulfate is 15-35%, and the concentration of permanganate is 1-10%.
13. A method for repairing a chlorinated hydrocarbon contaminated site according to claim 10, wherein: the concentration of persulfate is 20-30%, and the concentration of permanganate is 2-6%.
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