CN114289493A - System and method for repairing polluted soil - Google Patents
System and method for repairing polluted soil Download PDFInfo
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- CN114289493A CN114289493A CN202111660767.3A CN202111660767A CN114289493A CN 114289493 A CN114289493 A CN 114289493A CN 202111660767 A CN202111660767 A CN 202111660767A CN 114289493 A CN114289493 A CN 114289493A
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Abstract
The invention provides a system and a method for repairing polluted soil, belongs to the field of soil repair, and solves the defects that energy is wasted due to large temperature difference of soil in a heating process in the prior art, and the treatment effect of pollutants at different parts of the soil is greatly different due to the fact that the part with lower temperature cannot realize heat strengthening assisted in-situ chemical oxidation for repairing organic polluted soil. The system for repairing the polluted soil comprises a heating unit and a pumping and injecting device for extracting underground water in the soil and injecting a repairing medicament into the soil.
Description
Technical Field
The invention belongs to the field of soil remediation, and particularly relates to a system and a method for remediating contaminated soil.
Background
The existing in-situ remediation technology for the organic contaminated soil mainly comprises in-situ thermal desorption, in-situ chemical oxidation and soil vapor extraction technology. The in-situ thermal desorption technology has high restoration efficiency, wide range of pollutants to be processed and thorough restoration effect, but the polluted soil needs to be heated to a high enough temperature (generally more than 100 ℃) to volatilize the pollutants, the engineering quantity is large, the energy consumption is extremely high, and the restoration cost is high. The chemical oxidation technology reduces or removes pollutants in a field through the oxidation characteristic of a chemical oxidant, the repair period is short, the cost is low, but in the method, the repair agent and the pollutants are subjected to chemical reaction at proper temperature, the reaction is slow in actual use, the radius of the influence of the heterogeneity of the soil is small, the pollutants in the soil cannot be effectively and comprehensively oxidized and degraded, and the pollution rebounds to form a tailing effect after the repair. The soil vapor extraction technology is a technology for generating negative pressure by using a vacuum pump for extraction, forming airflow through a soil matrix and taking volatile organic pollutants away from soil, but the technology is only suitable for volatile organic compounds with high Henry coefficients, and has the problems of low treatment efficiency, high large-scale application cost, long soil remediation time and the like.
For example, chinese patent CN110014036A discloses a method for repairing organic contaminated soil by in-situ chemical oxidation assisted by thermal enhancement, which achieves the purpose of repairing soil by chemical oxidation by simply combining a high-pressure jet injection device and a heating device. However, the invention simply and continuously operates chemical oxidation and soil heating, the heating range is not large, the soil cannot be uniformly heated, the position far away from the heating device can still be in an unheated state when overheating occurs near the heating device, on one hand, energy is wasted, on the other hand, the temperature difference in the soil is large, the part with lower temperature cannot realize heat strengthening auxiliary in-situ chemical oxidation to repair the organic polluted soil, the treatment effect of pollutants at different parts of the soil is larger, the treatment effect of a low-temperature area is poor, and the pollutants in an adsorption state are reversely permeated into underground water after the treatment is stopped for a period of time, so that the phenomena of rebound and tailing of the pollutants are caused.
Disclosure of Invention
Therefore, the technical problems to be solved by the invention are to overcome the defects that energy is wasted due to large temperature difference of soil in the heating process and the treatment effect of pollutants at different parts of the soil is greatly different due to the fact that the parts with lower temperature cannot realize heat strengthening assisted in-situ chemical oxidation to repair the organic polluted soil in the prior art, so that the system and the method for repairing the polluted soil are provided.
Therefore, the invention provides the following technical scheme.
In a first aspect, a system for remediating contaminated soil is provided, comprising a heating unit and a pumping and injecting device for extracting groundwater from the soil and injecting remediation agent into the soil.
Furthermore, the pumping and injecting device comprises a pumping and injecting pipeline, a pumping and injecting well, and a vacuum pump and an injection pump which are respectively connected with the pumping and injecting pipeline.
Furthermore, the pumping and injecting pipelines are arranged in a plurality of rows at intervals, each pumping and injecting pipeline comprises a first group of pumping and injecting pipelines and a second group of pumping and injecting pipelines, and each row of pumping and injecting pipelines in the first group of pumping and injecting pipelines and the second group of pumping and injecting pipelines are alternately arranged.
Further, at least one of the following (1) to (2) is satisfied:
(1) the heating units are provided in plurality; preferably, a plurality of the heating units are arranged in the soil to be repaired at intervals according to a triangle method, and more preferably, the triangle method is a regular triangle method;
(2) and a plurality of pumping and injecting wells are arranged at intervals on each row of pumping and injecting pipelines, preferably, the pumping and injecting wells are distributed according to a triangular method, and more preferably, the triangular method is a regular triangular method.
Further, the heating unit is an electrically driven heating rod or a heating pipe driven by hot circulating water; and/or the presence of a gas in the gas,
further, the injection pump is an injection diaphragm pump or a peristaltic pump.
In a second aspect, a method for remediating contaminated soil is provided, and the system for remediating contaminated soil, which is adopted, comprises the steps of heating the soil to be remediated, extracting groundwater, and injecting remediation agents.
Further, after heating for 3-5 days, heating and simultaneously performing pre-extraction treatment on the underground water at least once every day; preferably, in the process of each pre-extraction treatment, when the extracted water amount is reduced to 50-70% of the extraction peak value or after extraction is carried out for 20-40 min, the extraction is finished.
Further, heating the average temperature of the soil to be repaired to 40-60 ℃, and then carrying out underground water extraction treatment and restoration agent injection treatment; preferably, the groundwater extraction treatment and the remediation agent injection treatment are carried out under the heat preservation condition of 40-60 ℃.
Further, the groundwater extraction treatment and the injection remediation agent treatment comprise the following steps:
preferably, steps 1-2 and steps 3-4 are performed alternately.
Further, in the step 2, underground water extraction treatment and remediation agent injection treatment are repeated for 1-3 times every day for 7-10 days; and/or the presence of a gas in the gas,
in the step 4, underground water extraction treatment and restoration agent injection treatment are repeated for 1-3 times every day, and the treatment is repeated for 7-10 days;
further, at least one of conditions a-C is satisfied:
A. the repairing agent is at least one of an oxidizing agent, a reducing agent and a bio-promoting agent; preferably, the oxidizing agent is selected from at least one of hydrogen peroxide, persulfate and potassium permanganate; the reducing agent is at least one selected from sodium hydroxide solution and vegetable oil; the biological promoting agent is at least one selected from biological carbon source and urea;
preferably, the total application amount of the oxidation medicament is 0.5-2% of the mass of the soil to be repaired;
C. the injection pressure of the repairing agent is 0.1MPa (normal pressure) to 1 MPa.
The repairing agent can be injected under normal pressure (0.1MPa), namely the repairing agent can be injected by self gravity under the condition of no external pressure of an injection pump.
Illustratively, the vegetable oil is rapeseed oil; the biological carbon source is formic acid or potassium bicarbonate.
Furthermore, after the concentration of the pollutants is reduced to be below the target value, the medicines are continuously injected for 5-30 days, and the repairing effect is consolidated.
Preferably, the method for restoring the polluted soil is applicable to a saturated water-containing soil layer with certain permeability from silt to medium sand. Hydraulic conductivity in the range of 10-4～10-6cm/s.
When the repairing medicaments comprise a plurality of repairing medicaments, the repairing medicaments are directly injected after being mixed according to the mixture ratio; or when the condition of reducing before oxidizing underground needs to be considered, the reducing agent is injected first, and then the oxidizing agent is injected.
Further, when the organic contaminant is a chlorinated hydrocarbon, the repairing agent includes a reducing agent and an oxidizing agent, and the condition of reduction and then oxidation needs to be considered. When the soil is treated, the reducing agent is injected first, and then the oxidizing agent is injected.
Specifically, (1) starting a first group of pumping and injecting pipelines to extract the underground water, and closing the first group of pumping and injecting pipelines to stop the underground water extraction when the pumped water amount is reduced to 50-70% of the initial extraction peak value; injecting partial reducing agent by adopting a second group of pumping and injecting pipelines, wherein the injection pressure of the reducing agent is 0.1-1 MPa, and the PH value is adjusted to 9-12, preferably 12;
(2) repeating the step (1) for 1-3 times every day, stabilizing the pH value to about 12, repeating the step for 5-7 days, and continuously reacting for 2-5 days, wherein no extraction and injection agent is required in the reaction process;
(3) starting a second group of pumping and injecting pipelines to extract the underground water, and closing the two groups of pumping and injecting pipelines to stop the underground water extraction when the pumped water amount is reduced to 50-70% of the initial extraction peak value; injecting partial reducing agent by adopting a first group of pumping and injecting pipelines, wherein the injection pressure of the reducing agent is 0.1-1 MPa;
(4) repeating the step (3) 1-3 times every day, stabilizing the pH value to about 12, repeating the step for 5-7 days, and continuously reacting for 2-5 days, wherein no extraction and injection agent is required in the reaction process;
(5) starting a first group of pumping and injecting pipelines to extract the underground water, and closing the first group of pumping and injecting pipelines to stop the underground water extraction when the pumped water amount is reduced to 50-70% of the initial extraction peak value; injecting partial oxidation agent by using a second group of pumping and injecting pipelines, wherein the injection pressure of the oxidation agent is 0.1 MPa-1 MPa;
(6) repeating the step (5) 1-3 times every day for 7-10 days;
(7) starting a second group of pumping and injecting pipelines to extract the underground water, and closing the two groups of pumping and injecting pipelines to stop the underground water extraction when the pumped water amount is reduced to 50-70% of the initial extraction peak value; injecting partial oxidation agent by adopting a first group of pumping and injecting pipelines, wherein the injection pressure of the oxidation agent is 0.1 MPa-1 MPa;
(8) repeating the step (7) 1-3 times every day for 7-10 days;
(9) alternately carrying out the steps (1) - (4) and the steps (5) - (8) until the pollutants in the soil are reduced to be below a target value, and completing soil remediation; preferably, after the concentration of the pollutants in the soil is reduced to be below a target value, the agents are continuously injected for 5-30 days, and the repairing effect is consolidated.
The technical scheme of the invention has the following advantages:
1. the system for repairing the polluted soil comprises a heating unit and a pumping and injecting device; the pumping and injecting device is used for extracting underground water in soil and injecting a repairing medicament into the soil. The pumping and injecting device accelerates the flow of underground water by pumping the underground water in the soil, drives heat conduction to rise temperature and reduces the temperature difference of different areas in the soil. On one hand, the waste of energy is reduced, compared with the traditional high-temperature in-situ thermal desorption system, the soil average temperature can be heated to the target temperature and enters a heat preservation state only by providing a small amount of heat, and pollutants are effectively degraded, so that the energy consumption is greatly reduced, and through the development of the technical demonstration project, the restoration can reach the standard only by consuming about 30% of the energy of the traditional in-situ heating technology. On the other hand, the whole soil can be ensured to realize heat strengthening assisted in-situ chemical oxidation remediation. The heating can promote the desorption of the pollutants in the adsorption state in the soil and then the pollutants are removed by the restoration medicament, and the invention can realize more uniform heating of the whole soil, thereby avoiding the poor treatment effect of a low-temperature area caused by uneven heating, and avoiding the phenomena of rebound and tailing of the pollutants caused by the reverse osmosis of the pollutants in the adsorption state into the underground water after the treatment is stopped for a period of time.
And the groundwater extracted from the soil can form negative pressure in the soil, so that the propagation of a remediation medicament in the soil is promoted, the influence radius of the remediation medicament is increased, and the heat-strengthening auxiliary in-situ chemical oxidation remediation can be further realized in the soil. Meanwhile, the problems that in the prior art, in order to enlarge the propagation radius of the repairing agent in the soil stalk, high-pressure jet grouting injection is adopted, a large amount of repairing agent needs to be injected, soil fracturing can be caused to form cracks, the agent is preferentially distributed in the cracks, the agent can not be uniformly distributed, the agent is not in sufficient contact with pollutants, and true thermal oxidation repairing can not be realized are solved.
2. The system for restoring the polluted soil comprises a first group of pumping and injecting pipelines and a second group of pumping and injecting pipelines, wherein each row of pumping and injecting pipelines in the first group of pumping and injecting pipelines and the second group of pumping and injecting pipelines are alternately arranged. Through the alternative arrangement of the first group of pumping and injecting pipelines and the second group of pumping and injecting pipelines, the isolated extraction can be realized, and the treatment effect is better.
3. According to the system for repairing the polluted soil, the number of the heating units is multiple; preferably, a plurality of the heating units are arranged in the soil to be repaired at intervals according to a triangular method; the pumping and injecting pipelines are arranged in a plurality of rows at intervals; and a plurality of pumping and injecting wells are arranged at intervals on each row of pumping and injecting pipelines, and the pumping and injecting wells are distributed according to a triangular method. The heating units and the pumping and injection pipelines are arranged, so that the distribution uniformity of heating, underground water extraction and injected drugs can be improved, and the treatment effect is better because the heating units and the pumping and injection wells are distributed according to a triangular method.
4. The method for repairing the polluted soil provided by the invention comprises the following steps: heating the soil to be repaired, extracting underground water, and injecting a repairing agent. The in-situ heating technology is coupled with the in-situ chemical oxidation technology and/or the in-situ chemical reduction technology and/or the in-situ microorganism technology, the underground water is driven to flow through extraction, the field soil can be efficiently and uniformly heated, the defect of nonuniform heating of the conventional in-situ heat conduction technology in the vicinity of a heating well with high temperature and low cold point temperature is overcome, a uniform soil temperature environment is provided, desorption of pollutants in an adsorption state in the soil is promoted, meanwhile, a remediation medicament is rapidly thermally activated under a heating condition, effective degradation of organic pollutants in the soil is realized, the improved in-situ chemical and microorganism promotion technology has high remediation efficiency, more consistent remediation effect on pollutants in different areas of the soil can be realized, and meanwhile, the time of the whole soil remediation process can be effectively shortened.
5. The method for restoring the polluted soil provided by the invention comprises the step of heating for 3-5 days, and simultaneously carrying out pre-extraction treatment on the underground water at least once every day. The groundwater in the soil is extracted at the in-process of heating, can accelerate groundwater to flow, drive heat-conduction intensification, reduce the temperature difference of different regions in the soil, realize the whole relatively even heating to soil, avoided the heating inequality to cause the regional treatment effect of low temperature not good, the pollutant of adsorption state is reverse osmosis again to the groundwater after stopping administering a period of time, causes the condition of phenomenon such as pollutant resilience, tailing.
The effective time of the remediation agent is limited, generally ranges from 1 day to 1 month, the soil heating rate is slow, if the agent is injected and then heated, the remediation agent may lose efficacy when the thermal field arrives, and the agent is injected under the condition of heat preservation after the soil temperature is raised to the target temperature, so that the combination effect of the thermal field and the remediation agent can be ensured.
6. The method for restoring the polluted soil provided by the invention comprises the following steps of underground water extraction treatment and restoration agent injection treatment: step 1, starting a first group of pumping and injecting pipelines to perform groundwater extraction treatment, finishing the extraction, and injecting a repairing medicament by adopting a second group of pumping and injecting pipelines; step 2, repeating the step 1; step 3, opening a second group of pumping and injecting pipelines to perform groundwater extraction treatment, finishing the extraction, and injecting a repairing medicament into the first group of pumping and injecting pipelines; step 4, repeating the step 3; preferably, steps 1-2 and steps 3-4 are performed alternately.
By adopting the modes of isolated extraction and intermittent pumping and injecting, the injected medicament can be better diffused by the water head difference and the negative pressure, and the uniformity of influencing the radius and distribution is improved, so that the removal effect of pollutants in different areas of soil is ensured.
Compared with the traditional in-situ chemical oxidation repair technology, the method has wider applicable pollutant concentration range, and breaks through the concentration interval that the traditional in-situ chemical oxidation repair technology can not realize the standard repair. By the development of the demonstration engineering of the technology, the consumption of the chemical agent is only about 50% of the target addition of the traditional in-situ chemical oxidation technology, and the problems of rebound and tailing which are usually caused by the conventional chemical oxidation are avoided.
7. The injection pressure of the remediation agent in the method for remediating the polluted soil is 0.1MPa to 1 MPa. The repairing agent has lower injection pressure, does not cause soil cracks during injection, can be matched with proper negative pressure caused by groundwater extraction, and can obtain larger influence radius and better distribution uniformity in soil.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic structural view of a system for remediating contaminated soil according to example 1 of the present invention;
FIG. 2 is a schematic view of the local distribution of the heating unit and the pumping well in the embodiment 1 of the present invention;
FIG. 3 shows temperature monitoring points T5(1.5m), T6(1.73m), T7(0.5m) and T8(1m) at different distances from a heater well H6 in example 2 of the present invention;
FIG. 4 is a temperature monitoring chart of temperature monitoring points in example 2;
(a) a T5 temperature monitoring graph, (b) a T6 temperature monitoring graph, (c) a T7 temperature monitoring graph, and (d) a T8 temperature monitoring graph;
FIG. 5 is a graph of the concentration of four contaminants in groundwater in example 2;
(a) a chloroform concentration change curve, (b) a trichloroethylene concentration change curve, (c) a tetrachloroethane concentration change curve, and (d) a tetrachloroethylene concentration change curve;
FIG. 6 is a temperature monitoring diagram of temperature monitoring points at different distances from the same heating well in comparative example 1;
(a) a T9(1.5m) temperature monitoring graph, (b) a T10(1m) temperature monitoring graph, and (c) a T11(0.5m) temperature monitoring graph;
FIG. 7 is a graph showing the concentration of four contaminants in groundwater in comparative example 1;
(a) a chloroform concentration change curve, (b) a trichloroethylene concentration change curve, (c) a tetrachloroethane concentration change curve, and (d) a tetrachloroethylene concentration change curve;
reference numerals:
1-pumping and injecting well; 2-pumping and injecting pipeline; 201-first set of suction and injection lines; 202 a second set of pump lines; 3-a syringe pump; 4-a vacuum pump; 5-heating unit.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
Example 1
The embodiment provides a system for remediating contaminated soil, as shown in fig. 1 and 2, comprising a heating unit 5 and a pumping device; the pumping and injecting device is used for extracting underground water in soil and injecting a repairing medicament into the soil. The heating unit 5 is exemplarily an electrically driven heating rod or a hot water driven heating tube.
The heating unit 5 is used for heating contaminated soil, and the pumping and injecting device accelerates the flow of underground water by pumping the underground water in the soil, promotes high-temperature underground water near the heating unit 5 to migrate to a low-temperature area and drives heat conduction to rise temperature, and reduces the temperature difference of different areas in the soil.
Specifically, the pumping device comprises a pumping pipeline 2, and a vacuum pump 4 and a syringe pump 3 which are respectively connected with the pumping pipeline 2. Illustratively, the vacuum pump 4 is a water ring vacuum pump 4 and the syringe pump 3 is an infusion diaphragm pump or a peristaltic pump. When underground water needs to be extracted from the soil, the vacuum pump 4 is started; when the soil needs to be injected with the remediation agent, the injection pump 3 is started.
The pumping and injecting pipelines 2 are arranged in a plurality of rows at intervals, the pumping and injecting pipelines 2 comprise a first group of pumping and injecting pipelines 201 and a second group of pumping and injecting pipelines 202, and the first group of pumping and injecting pipelines 201 and the second group of pumping and injecting pipelines 202 are arranged at intervals. The groundwater is extracted using either the first set of extraction lines 201 or the second set of extraction lines 202, and then remediation agents are injected using the other set of extraction lines. The water head difference and the negative pressure brought by the alternate extraction can enable the injected medicament to be better diffused, and the uniformity of influencing the radius and distribution is improved, so that the repair efficiency of chemical oxidation is promoted.
A plurality of heating units 5 are arranged and uniformly distributed in the polluted soil area; the pumping and injection pipelines 2 are provided with a plurality of rows and uniformly spread over the polluted soil area, and a plurality of pumping and injection wells 1 are arranged at intervals on each row of pumping and injection pipelines 2. Preferably, the heating units 5 are uniformly distributed according to a triangular method, and more preferably, the heating units 5 are uniformly distributed according to a regular triangular method in the present embodiment. The plurality of pumping and injecting wells 1 are distributed according to a triangular method, more preferably, the plurality of pumping and injecting wells 1 are distributed according to a regular triangle in the embodiment, the distance between the two heating units 5 is 2.5-5 m, and the distance between the two pumping and injecting wells 1 is 4-8 m. Illustratively, as shown in fig. 2, the distance between two heating units 5 is 3m in the present embodiment, and the distance between two pumping wells 1 is 4 m.
The system for remediating contaminated soil also includes a temperature monitoring unit, which may be, for example, a conventional temperature sensor, and is preferably provided in plurality, evenly distributed over the contaminated soil area, for detecting the temperature throughout the contaminated soil area.
Example 2
The embodiment provides a method for restoring polluted soil, wherein the soil to be restored is a silt saturated water-bearing soil layer, and the hydraulic conductivity is 10-5～10-6cm/s. The organic pollutants comprise chloroform, trichloroethylene, tetrachloroethylene and tetrachloroethane (specifically 1,1,2,2 tetrachloroethane), and the remediation agent comprises: 10 percent of sodium persulfate solution and 32 percent of sodium hydroxide solution by mass, and the amount of the soil to be repaired is 2800m3(about 5000 tons), the total application amount of the sodium persulfate for completing the restoration is 25 tons, the sodium hydroxide solution is 9 cubic meters, and the total application amount of the sodium persulfate is 0.5 percent of the mass fraction of the soil to be restored.
The embodiment provides a method for restoring polluted soil, in particular to the system for restoring polluted soil of the embodiment 1, which comprises the following steps:
s1, heating soil to be repaired by adopting a heating unit;
s2, starting a vacuum pump and all pumping and injecting pipelines after heating is started for 5 days, pre-extracting the underground water in the soil, finishing extraction after the pumped water amount is reduced to 70% of the initial extraction peak value, and repeating pre-extracting the underground water for 2 times every day; and when the average temperature of the soil to be restored reaches 55 ℃, preserving the heat.
S3, (1) starting a first group of pumping and injecting pipelines to extract the underground water, and when the pumped water amount is reduced to 70% of the initial extraction peak value, closing the first group of pumping and injecting pipelines and stopping the extraction of the underground water; and (3) injecting a sodium hydroxide solution by adopting a second group of pumping and injecting pipelines, wherein 167L of the sodium hydroxide solution is injected each time, and the injection pressure of the sodium hydroxide solution is 0.1 MPa.
(2) Repeating the step (1)2 times every day for 7 days, and then carrying out heat preservation reaction for 3 days to enable the sodium hydroxide solution to react with pollutants;
(3) starting a second group of pumping and injecting pipelines to extract the underground water, and closing the two groups of pumping and injecting pipelines to stop the extraction of the underground water after the pumped water amount is reduced to 70 percent of the initial extraction peak value; and (3) injecting a sodium hydroxide solution by adopting a first group of pumping and injecting pipelines, wherein 167L of the sodium hydroxide solution is injected each time, and the injection pressure of the sodium hydroxide solution is 0.1 MPa.
(4) Repeating the step (3)2 times every day for 7 days, and then carrying out heat preservation reaction for 3 days to enable the sodium hydroxide solution to react with pollutants;
(5) starting a first group of pumping and injecting pipelines to extract the underground water, closing the first group of pumping and injecting pipelines when the pumped water amount is reduced to 70% of the initial extraction peak value, and stopping the underground water extraction; injecting sodium persulfate solution by adopting a second group of pumping and injecting pipelines, wherein the application amount of sodium persulfate is 625kg each time, and the injection pressure of the sodium persulfate solution is 0.1 MPa;
(6) repeating the step (5)2 times every day for 10 days;
(7) starting a second group of pumping and injecting pipelines to extract the underground water, and closing the two groups of pumping and injecting pipelines to stop the extraction of the underground water after the pumped water amount is reduced to 70 percent of the initial extraction peak value; injecting sodium persulfate solution by adopting a first group of pumping and injecting pipelines, wherein the application amount of sodium persulfate is 625kg each time, and the injection pressure of the sodium persulfate solution is 0.1 MPa;
(8) repeating the step (7)2 times every day for 10 days;
(9) the steps (1) to (4) and the steps (5) to (8) are alternately performed.
As shown in fig. 5, the time when the remediation agent was injected is day 0, 39 days after the agent injection, the contaminants in the soil were reduced to a target value or less, and the agent injection was continued for 56 days to complete the soil remediation.
Example 3
This example provides a method for remediating contaminated soil, which is a high permeability field with a hydraulic conductivity of 10-4～10-5cm/s. The organic pollutants are benzene series petroleum hydrocarbon, including benzene, toluene, xylene and ethylbenzene, and the repairing agent is: 10 percent of sodium persulfate solution by mass, and the volume of the soil to be repaired is 5500m3(about 10000 tons), the total application amount of the remediation agent is 100 tons, and the total application amount is 1 percent of the mass of the polluted soil to be remediated.
In this embodiment, the system for remediating contaminated soil of embodiment 1 is adopted, and the method for remediating contaminated soil includes the following steps:
s1, heating soil to be repaired at low temperature by adopting a heating unit;
s2, starting a vacuum pump and all pumping and injecting pipelines after heating for 5 days, pre-extracting the underground water in the soil, finishing extraction after 20min of each extraction, repeating the pre-extraction of the underground water for 3 times each day, and preserving heat when the average temperature of the soil to be repaired reaches 60 ℃.
S3, (1) starting a first group of pumping and injecting pipelines to extract underground water, closing the first group of pumping and injecting pipelines after 20min of extraction, and stopping underground water extraction; injecting sodium persulfate solution by using a second group of pumping and injecting pipelines, wherein the injection pressure of the sodium persulfate solution is 0.5 Mpa;
(2) repeating the step (1)1 time every day for 7 days;
(3) opening a second group of pumping and injecting pipelines to extract the underground water, closing the two groups of pumping and injecting pipelines after 20min of extraction, and stopping the extraction of the underground water; injecting sodium persulfate solution by adopting a first group of pumping and injecting pipelines, wherein the injection pressure of the sodium persulfate solution is 0.5 Mpa;
(4) repeating the step (3)1 time every day for 7 days;
(5) and (3) alternately performing the steps (1) and (2) and the steps (3) and (4), and finishing the remediation of the soil to be remediated when the concentration of the pollutants is reduced to be below a target value.
Example 4
This example provides a method for remediating contaminated soil having a hydraulic conductivity of 10-5～10-6cm/s。The organic pollutant is polycyclic aromatic hydrocarbon including naphthalene, anthracene, phenanthrene, and benzo [ a ]]Pyrene. The repairing medicament is: 10 percent of sodium persulfate solution by mass, and the amount of soil to be repaired is 2800m3(about 5000 tons), the total application amount of the remediation agent is 80 tons, which is 1.6 percent of the mass of the polluted soil to be remediated.
In this embodiment, the system for remediating contaminated soil of embodiment 1 is adopted, and the method for remediating contaminated soil includes the following steps:
s1, heating soil to be repaired at low temperature by adopting a heating unit;
and S2, starting a vacuum pump and all pumping and injecting pipelines after heating is started for 4 days, pre-extracting the underground water in the soil, finishing extraction after the amount of the pumped water is reduced to 60% of the initial extraction peak value, repeating the pre-extraction of the underground water for 3 times every day, and preserving heat after the average temperature of the soil to be repaired reaches 50 ℃.
S3, (1) starting a first group of pumping and injecting pipelines to extract the underground water, and when the amount of the extracted water is reduced to 60% of the extraction starting peak value, closing the first group of pumping and injecting pipelines and stopping the extraction of the underground water; injecting sodium persulfate solution by using a second group of pumping and injecting pipelines, wherein the injection pressure of the sodium persulfate solution is 0.3 Mpa;
(2) repeating the step (1)3 times every day for 8 days;
(3) starting a second group of pumping and injecting pipelines to extract the underground water, and closing the two groups of pumping and injecting pipelines to stop the underground water extraction when the pumped water amount is reduced to 60 percent of the initial extraction peak value; injecting sodium persulfate solution by using a first group of pumping and injecting pipelines, wherein the injection pressure of the sodium persulfate solution is 0.3 Mpa;
(4) repeating the step (3)3 times every day for 8 days;
(5) and (3) alternately performing the steps (1) and (2) and the steps (3) and (4), and finishing the remediation of the soil to be remediated when the concentration of the pollutants is reduced to be below a target value.
Comparative example 1
The comparative example provides a method for remediating contaminated soil, in which the contaminated site, the type and amount of remediation drug, and the injection method of remediation drug are the same as those in example 2, except that groundwater extraction is not performed in the temperature rise process and the subsequent drug injection process.
The method comprises the following steps:
s1, heating soil to be repaired by adopting a heating unit;
s2, the heating time is the same as the time adopted in the heating process of S2 in the embodiment 2;
s3, (1) injecting sodium hydroxide solution by adopting a second group of pumping and injecting pipelines, wherein the injection pressure of the sodium hydroxide solution is 0.1 MPa.
(2) Repeating the step (1)2 times every day for 7 days, and then carrying out heat preservation reaction for 3 days to enable the sodium hydroxide solution to react with pollutants;
(3) and injecting sodium hydroxide solution by adopting a first group of pumping and injecting pipelines, wherein the injection pressure of the sodium hydroxide solution is 0.1 MPa.
(4) Repeating the step (3)2 times every day for 7 days, and then carrying out heat preservation reaction for 3 days to enable the sodium hydroxide solution to react with pollutants;
(5) injecting sodium persulfate solution by adopting a second group of pumping and injecting pipelines, wherein the injection pressure of the sodium persulfate solution is 0.1 MPa;
(6) repeating the step (5)2 times every day for 10 days;
(7) injecting sodium persulfate solution by adopting a first group of pumping and injecting pipelines, wherein the injection pressure of the sodium persulfate solution is 0.1 MPa;
(8) repeating the step (7)2 times every day for 10 days;
(9) steps (1) to (4) and steps (5) to (8) were alternately performed, and the time from the start of injection of the drug to the end of the treatment was the same as in example 2.
Experimental example 1
The contents of groundwater pollutants before and after soil remediation of example 2 and comparative example 1 were detected according to HJ 605-2011- -measurement of volatile organic compounds in soil and sediments- -gas chromatography-Mass Spectrometry ". Organic contaminants include vinyl chloride, cis-1, 2-dichloroethylene, chloroform, 1, 2-dichloroethane, trichloroethylene, 1, 2-trichloroethane, tetrachloroethane, tetrachloroethylene, and hexachlorobutadiene. Various pollutants at random monitoring points (respectively marked as M1-M5) in the soil are detected at different times, the moment when the remediation agent is just injected is marked as day 0, the temperature rise process without the injection agent is carried out before 0, and the time is marked as a negative number. The results of the detection are shown in tables 1 and 2, and ND is not detected.
Table 1 example 2 pollutant remediation targets and pollutant levels
Table 2 comparative example 1 groundwater contaminant content
As can be seen from fig. 5 and table 1, the concentrations of the organic contaminants chloroform, trichloroethylene, tetrachloroethane, and tetrachloroethylene at the four monitoring points of the contaminants of example 2 were all reduced below the target values 39 days after the injection of the chemical, and the concentrations of the contaminants remained below the target values after the injection of the chemical continued for 56 days without a rebound. And after the treatment is finished, the organic pollutants are detected again every 3 months, and no rebound phenomenon exists.
As can be seen from fig. 7 and table 2, the pollutant concentration of comparative example 1 is not reduced below the target value after the pollutant is injected for 39 days, and the pollutant concentration rebounds after the pollutant is injected for 56 days, so the soil remediation effect is poor and incomplete. And after the treatment is finished, the organic pollutants are detected again every 3 months, and rebound occurs.
FIG. 4 is a temperature monitoring graph of the temperature monitoring points in example 2, and each of the graphs (a) to (d) in FIG. 4 contains temperature monitoring curves of the same temperature monitoring point at different distances (1m, 4.5m, 8m, 11.5m, 15m) from the ground.
FIG. 6 is a graph showing temperature monitoring at different distances from the same well in comparative example 1, where the distance T9 was 1.5m, the distance T10 was 1m, and the distance T11 was 0.5 m. Each of the graphs (a) - (d) in FIG. 6 also contains temperature monitoring curves of the same temperature monitoring point at different distances (1m, 4.5m, 8m, 11.5m, 15m) from the ground.
As can be seen from fig. 3 and 4, the temperature monitoring points at different distances from the same heating well have the same heating rate in the temperature rise stage, the heating effect achieved by temperature rise is the same, and the temperature ranges of the different temperature monitoring points after 45 days of heating are also the same, which shows the uniformity of heating in the invention. As can be seen from FIG. 6, in comparative example 1 in which groundwater extraction was not performed, the temperature rise rates of different temperature monitoring points were significantly different, the heating effects achieved by the temperature rise were different, the temperature ranges of the different temperature monitoring points after 45 days of heating were greatly different, the temperature near the heating well was 50-70 degrees, while the temperature in the region farther from the heating well was still only 20-30 degrees, and the soil temperature difference was large.
FIG. 5 is a graph of the concentration of four contaminants in groundwater as in example 2, (a) - (d) each of which contains the concentration of contaminants at four different locations M1, M2, M3, M4; fig. 7 is a graph showing the concentration change of four contaminants in groundwater in comparative example 1. The soil restoration effect of the invention is obviously higher than the restoration effect of combining heating and restoration agents without underground water extraction.
The energy consumption of the method is only about 34% of that of the traditional in-situ heating restoration in the same site (the traditional in-situ heating is only heated to 100 ℃, and the volatile pollutant steam is always extracted and removed in the process), and the restoration of the polluted soil can be completed under the condition that the injection amount of the restoration agent is only 30% (mass ratio) of the consumption amount of the restoration agent for the in-situ chemical oxidation restoration in the same site, so that the acceptance is realized. And the invention also breaks through the limitation that the single-purification chemical injection in the same field can not reach the standard. Traditional in-situ chemical injection is suitable for restoring chlorohydrocarbons with lower than medium concentration, for example, the concentration of chlorohydrocarbons in underground water is higher by a plurality of PPM levels, a tailing effect is formed, and the pollution concentration rebounds after chemical injection reaction. The method can be carried out in the range of the concentration of the chlorinated hydrocarbon being hundreds to 1000PPM, as shown in figure 5, the sum of the highest concentration of four pollutants in the example 2 is as high as more than 600 PPM.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (10)
1. The system for restoring the polluted soil is characterized by comprising a heating unit and a pumping and injecting device for extracting underground water in the soil and injecting restoring agents into the soil.
2. The system for remediating contaminated soil as recited in claim 1, wherein said pumping means comprises a pumping line, a pumping well, and a vacuum pump and an injection pump respectively connected to the pumping line.
3. The system for remediating contaminated soil as recited in claim 1 or 2, wherein the pumping lines are spaced in a plurality of rows, the pumping lines comprising a first group of pumping lines and a second group of pumping lines, each row of the first group of pumping lines and the second group of pumping lines being alternately arranged.
4. The system for remediating contaminated soil as recited in any one of claims 1 to 3, wherein at least one of the following (1) to (2) is satisfied:
(1) the heating units are provided in plurality; preferably, a plurality of the heating units are arranged in the soil to be repaired at intervals according to a triangular method;
(2) a plurality of pumping and injecting wells are arranged at intervals on each row of pumping and injecting pipelines, and preferably, the pumping and injecting wells are distributed in a triangular mode.
5. A method for remediating contaminated soil using the system for remediating contaminated soil as defined in any one of claims 1 to 4, comprising heating the soil to be remediated, extracting groundwater, and injecting remediation agent.
6. The method for remediating contaminated soil as recited in claim 5, further comprising performing pre-extraction treatment on the groundwater at least once a day after heating for 3 to 5 days; preferably, in the process of each pre-extraction treatment, when the extracted water amount is reduced to 50-70% of the extraction peak value or after extraction is carried out for 20-40 min, the extraction is finished.
7. The method for remediating contaminated soil as claimed in claim 6, wherein the average temperature of the soil to be remediated is heated to 40 to 60 ℃ and then groundwater extraction treatment and remediation agent injection treatment are performed; preferably, the groundwater extraction treatment and the remediation agent injection treatment are carried out under the heat preservation condition of 40-60 ℃.
8. The method for remediating contaminated soil according to any one of claims 5 to 7, wherein the groundwater extraction treatment and the injection remediation agent treatment comprise the steps of:
step 1, starting a first group of pumping and injecting pipelines to perform groundwater extraction treatment, finishing the extraction, and injecting a repairing medicament by adopting a second group of pumping and injecting pipelines;
step 2, repeating the step 1;
step 3, opening a second group of pumping and injecting pipelines to perform groundwater extraction treatment, finishing the extraction, and injecting a repairing medicament into the first group of pumping and injecting pipelines;
step 4, repeating the step 3;
preferably, steps 1-2 and steps 3-4 are performed alternately.
9. The method for remediating contaminated soil as set forth in claim 8,
in the step 2, underground water extraction treatment and restoration agent injection treatment are repeated for 1-3 times every day, and the treatment is repeated for 7-10 days; and/or the presence of a gas in the gas,
and 4, repeatedly extracting underground water and injecting a repairing agent for 1-3 times every day, and repeating for 7-10 days.
10. The method for remediating contaminated soil according to any one of claims 5 to 9, wherein at least one of conditions a-B is satisfied:
A. the repairing agent is at least one of an oxidizing agent, a reducing agent and a bio-promoting agent; preferably, the oxidizing agent is selected from at least one of hydrogen peroxide, persulfate and potassium permanganate; the reducing agent is at least one selected from sodium hydroxide solution and vegetable oil; the biological promoting agent is at least one selected from biological carbon source and urea; preferably, the total application amount of the oxidation medicament is 0.5-2% of the mass of the soil to be repaired;
B. the injection pressure of the repairing medicament is 0.1 MPa-1 MPa.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116037639A (en) * | 2023-01-31 | 2023-05-02 | 江苏省环境科学研究院 | Drip irrigation type automatic injection process and device for in-situ restoration agent of soil and underground water |
| CN116393501A (en) * | 2023-06-08 | 2023-07-07 | 北京建工环境修复股份有限公司 | Repairing system and method for trichloromethane polluted site |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008272597A (en) * | 2007-03-14 | 2008-11-13 | Dowa Eco-System Co Ltd | Method for treating polluted soil |
| CN104174643A (en) * | 2014-08-08 | 2014-12-03 | 北京建工环境修复股份有限公司 | In-situ restoration device and in-situ restoration method of organic polluted soil and underground water |
| CN205042871U (en) * | 2015-07-06 | 2016-02-24 | 环境保护部环境规划院 | Chlorohydrocarbon pollutes subregion repair system of soil and groundwater |
| CN107350278A (en) * | 2017-07-18 | 2017-11-17 | 中国地质大学（武汉） | Collaboration removes the in-situ remediation system and method for soil and groundwater organic pollution |
| WO2017219792A1 (en) * | 2016-06-23 | 2017-12-28 | 北京建工环境修复股份有限公司 | In situ repair system and method for in situ injection - high pressure rotary jet injection in soil and groundwater |
| CN109047305A (en) * | 2018-07-31 | 2018-12-21 | 南京格洛特环境工程股份有限公司 | Chemical pollution place soil and groundwater in-situ remediation system and restorative procedure |
| CN208912793U (en) * | 2018-07-20 | 2019-05-31 | 中冶南方都市环保工程技术股份有限公司 | Multiphase extraction system for gas station's soil and groundwater remediation |
| CN109848193A (en) * | 2018-12-31 | 2019-06-07 | 上海勘察设计研究院(集团)有限公司 | A kind of underground water in-situ remediation method based on waterpower barrier |
| CN110280581A (en) * | 2019-07-09 | 2019-09-27 | 浙江大学 | The method of Zero-valent Iron reduction joint persulfate oxidation remedying soil polluted by organic chloride |
| CN111069264A (en) * | 2019-12-31 | 2020-04-28 | 北京建工环境修复股份有限公司 | In-situ thermal desorption repair system and repair method for polluted site |
| CN112474768A (en) * | 2020-12-28 | 2021-03-12 | 苏州精英环保有限公司 | Electric heating reinforced in-situ chemical oxidation repairing device for organic polluted site |
| CN113182335A (en) * | 2021-04-26 | 2021-07-30 | 上海大学 | Extraction driving in-situ oxidation repair system |
-
2021
- 2021-12-31 CN CN202111660767.3A patent/CN114289493B/en active Active
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008272597A (en) * | 2007-03-14 | 2008-11-13 | Dowa Eco-System Co Ltd | Method for treating polluted soil |
| CN104174643A (en) * | 2014-08-08 | 2014-12-03 | 北京建工环境修复股份有限公司 | In-situ restoration device and in-situ restoration method of organic polluted soil and underground water |
| CN205042871U (en) * | 2015-07-06 | 2016-02-24 | 环境保护部环境规划院 | Chlorohydrocarbon pollutes subregion repair system of soil and groundwater |
| WO2017219792A1 (en) * | 2016-06-23 | 2017-12-28 | 北京建工环境修复股份有限公司 | In situ repair system and method for in situ injection - high pressure rotary jet injection in soil and groundwater |
| CN107350278A (en) * | 2017-07-18 | 2017-11-17 | 中国地质大学（武汉） | Collaboration removes the in-situ remediation system and method for soil and groundwater organic pollution |
| CN208912793U (en) * | 2018-07-20 | 2019-05-31 | 中冶南方都市环保工程技术股份有限公司 | Multiphase extraction system for gas station's soil and groundwater remediation |
| CN109047305A (en) * | 2018-07-31 | 2018-12-21 | 南京格洛特环境工程股份有限公司 | Chemical pollution place soil and groundwater in-situ remediation system and restorative procedure |
| CN109848193A (en) * | 2018-12-31 | 2019-06-07 | 上海勘察设计研究院(集团)有限公司 | A kind of underground water in-situ remediation method based on waterpower barrier |
| CN110280581A (en) * | 2019-07-09 | 2019-09-27 | 浙江大学 | The method of Zero-valent Iron reduction joint persulfate oxidation remedying soil polluted by organic chloride |
| CN111069264A (en) * | 2019-12-31 | 2020-04-28 | 北京建工环境修复股份有限公司 | In-situ thermal desorption repair system and repair method for polluted site |
| CN112474768A (en) * | 2020-12-28 | 2021-03-12 | 苏州精英环保有限公司 | Electric heating reinforced in-situ chemical oxidation repairing device for organic polluted site |
| CN113182335A (en) * | 2021-04-26 | 2021-07-30 | 上海大学 | Extraction driving in-situ oxidation repair system |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116037639A (en) * | 2023-01-31 | 2023-05-02 | 江苏省环境科学研究院 | Drip irrigation type automatic injection process and device for in-situ restoration agent of soil and underground water |
| CN116037639B (en) * | 2023-01-31 | 2023-10-03 | 江苏省环境科学研究院 | Drip irrigation type automatic injection process and device for in-situ restoration agent of soil and underground water |
| CN116393501A (en) * | 2023-06-08 | 2023-07-07 | 北京建工环境修复股份有限公司 | Repairing system and method for trichloromethane polluted site |
| CN116393501B (en) * | 2023-06-08 | 2023-08-29 | 北京建工环境修复股份有限公司 | Repairing system and method for trichloromethane polluted site |
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