Three-dimensional sand box simulation system for multiphase extraction remediation of soil and underground water and use method of three-dimensional sand box simulation system

Abstract

The invention discloses a three-dimensional sand box simulation system for soil and groundwater multiphase extraction remediation and a use method thereof.The three-dimensional sand box simulation system comprises a water supply mechanism, a sand box and an extraction remediation mechanism, a partition plate is fixedly installed in the sand box, a plurality of water distribution holes are formed in the surface of the partition plate in a penetrating mode, and the interior of the sand box is divided into a water distribution bin and a test bin through the partition plate; the test bin is used for filling a soil medium, a water inlet hole communicated with the water distribution bin is formed in the outer wall of the sand box in a penetrating manner, the water inlet hole is communicated with the water supply mechanism, and a plurality of water outlet holes communicated with the test bin are formed in the outer wall of the sand box in a penetrating manner; by arranging the sand box, the partition plate, the water distribution holes, the cover plate, the sampling holes, the extraction remediation mechanism and the like, the migration rule and the multiphase extraction remediation rule of volatile organic pollutants in a soil and underground water system can be accurately researched, so that the remediation scheme is optimized, scientific guidance is provided for actual remediation engineering, the remediation work efficiency is improved, and the economic benefit is increased. And the maximization of environmental benefits is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of contaminated soil and groundwater remediation, and in particular to a three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater and a method for using the system. Background Art

[0002] In recent years, in the remediation technology of contaminated soil and groundwater, judging from the development trend of research on multiphase extraction and remediation of contaminated sites at home and abroad, the existing sand box device has not conducted sufficient research on the optimization of multiphase extraction and remediation process parameters when exploring the multiphase extraction to remove volatile organic compound contaminated soil and groundwater, and has only stayed at the discussion of a single influencing factor.

[0003] In addition, most of the existing indoor device research simulating the migration and remediation of volatile organic pollutants in soil and groundwater systems remains at the horizontal two-dimensional sand box device, lacking research on the combination changes of process parameters such as well location and pressure considering three-dimensional depth, and unable to make a reasonable optimization reference for the actual construction parameters. The existing device research also does not take into account the volatilization loss of volatile organic compounds in the sand box system, and underestimates the residual concentration of pollutants in the sand box system.

[0004] To this end, we propose a three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater. Summary of the invention

[0005] The purpose of the present invention is to provide a three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater and a method of using the system, to explore the well layout mode and key process parameter optimization of multiphase extraction of volatile organic compounds in three-dimensional space in a relatively sealed environment, to simulate the technical parameter considerations and time-space combination control required for real engineering, and to provide technical support for the reasonable setting of well layout and process parameters for multiphase extraction and remediation of contaminated soil and groundwater in actual sites.

[0006] To achieve the above object, the present invention provides the following technical solutions: A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater, comprising a water supply mechanism, a sand box, and an extraction and remediation mechanism, wherein a partition is fixedly installed in the sand box, and a plurality of water distribution holes are penetrated on the surface of the partition, and the partition divides the interior of the sand box into a water distribution bin and a test bin, and the test bin is used to fill soil media, and a water inlet hole connected to the water distribution bin is penetrated on the outer wall of the sand box, and the water inlet hole is connected to the water supply mechanism, and a plurality of water outlet holes connected to the test bin are penetrated on the outer wall of the sand box, and a cover plate is sealably connected to the top of the sand box, and a plurality of sampling holes for penetrating the extraction and remediation mechanism are penetrated on the cover plate, and the extraction and remediation mechanism comprises an extraction outer tube, and an extraction inner tube is movably and sealably penetrated on the top of the extraction outer tube.

[0007] As a further solution of the present invention: a water storage box is fixedly installed on the outer wall of the sand box, the water outlet holes are connected to the water storage box, a drainage hole is penetrated through the bottom of the water storage box, and the drainage hole is connected to the water storage tank through a hose.

[0008] As a further solution of the present invention: the outer wall of the inner extraction tube is sleeved with a rubber sleeve, and the bottom end of the rubber sleeve is located in the top opening of the outer extraction tube.

[0009] As a further solution of the present invention: the bottom end of the outer extraction tube is blocked, and a plurality of sieve holes are provided through the bottom end of the outer wall of the outer extraction tube.

[0010] As a further solution of the present invention: the extraction and repair mechanism also includes a waste liquid barrel, the top opening of the waste liquid barrel is detachably sealed and connected to a barrel cover, the barrel cover is connected to a vacuum pump through an exhaust pipe, and the barrel cover is connected to the top of the extraction inner tube through a liquid extraction hose.

[0011] As a further solution of the present invention: the water supply mechanism includes a peristaltic pump, the peristaltic pump is connected to a water supply pipe, and the water outlet end of the water supply pipe is connected to the water inlet hole.

[0012] As a further solution of the present invention: a rubber plug is installed in the sampling hole.

[0013] As a further solution of the present invention: the method for using the above-mentioned three-dimensional sand box simulation system comprises the following steps: Step 1: Fill the prepared soil medium into the test chamber, and install the cover plate on the sand box, and each sampling hole on the cover plate is sealed with a rubber plug; Step 2: Use a peristaltic pump to pump pure water into the water distribution tank through the water supply pipe, so that the pure water can empty the air in the soil medium to form a saturated three-dimensional sand box model; Step 3: Select a sampling hole as the pollutant injection point, and use a syringe to inject the configured pollutant into the soil medium from the pollutant injection point multiple times, and do not apply external pressure during the injection process; Step 4: After the injection of pollutants, allow the pollutants to migrate freely in the soil medium under the action of gravity and water flow. Select multiple sampling holes near the injection point of the pollutants as monitoring points. Use a syringe to sample soil solutions at multiple depths at the monitoring points at different times during the migration process to determine the pollutant concentration of the samples. Step 5: After the migration of pollutants is completed, select the pollutant injection point and multiple sampling holes around it as the repair point, and set up the extraction and repair mechanism at the repair point, start the vacuum pump for extraction and repair, and use a syringe to sample the soil solution at multiple depths at the monitoring point at different times during the extraction and repair process. At the same time, sample the waste liquid in the waste liquid barrel and record the volume of the extracted waste liquid. Test the samples obtained from the monitoring point and the waste liquid barrel to observe the process and effect of multi-phase extraction and repair.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention can more accurately study the migration law and multiphase extraction and remediation law of volatile organic pollutants in soil and groundwater systems by arranging sand boxes, partitions, water distribution holes, covers, sampling holes and extraction and remediation mechanisms, thereby optimizing remediation plans, providing scientific guidance for actual remediation projects, improving the efficiency of remediation work, and maximizing environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater.

[0016] Figure 2 This is a schematic diagram of the structure of the sand box in a three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater.

[0017] Figure 3 This is a schematic diagram of the cross-sectional structure of a sand box in a three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater.

[0018] Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0019] Figure 5 Schematic diagram of the distribution of pollutant injection points, monitoring points and repair points in an embodiment of the present invention.

[0020] Among them, there are sand box 1, partition 2, water distribution hole 3, water distribution bin 4, test bin 5, water inlet hole 6, water outlet hole 7, water storage box 8, drainage hole 9, cover plate 10, sampling hole 11, rubber plug 12, lifting and extraction outer tube 13, sieve hole 14, rubber sleeve 15, lifting and extraction inner tube 16, water supply pipe 17, water storage tank 18, liquid extraction hose 19, waste liquid barrel 20, barrel cover 21, and air extraction pipe 22. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] See also Figures 1 to 4 In an embodiment of the present invention, a three-dimensional sand box simulation system for multiphase extraction and restoration of soil and groundwater includes a water supply mechanism, a sand box 1, and an extraction and restoration mechanism. The sand box 1 is made of a 1.5 cm thick organic glass plate, and its specific dimensions are 40 cm long, 30 cm wide, and 30 cm high. A partition 2 made of organic glass is fixedly installed in the sand box 1. The partition 2 is 1 cm thick, and its top is flush with the top of the sand box 1. A total of 196 water distribution holes 3 with a size of 14×14 are arranged on the surface of the partition 2. The aperture of the water distribution hole 3 is 0.5 mm, and the spacing between adjacent water distribution holes 3 is 2 cm. The partition 2 divides the interior of the sand box 1 into a water distribution bin 4 and a test bin 5. The test bin 5 is used to fill soil media. A hole 25 cm high in the center of the left outer wall of the sand box 1 is arranged through the water distribution bin 4. The water inlet hole 6 is connected, and the aperture of the water inlet hole 6 is 1 cm. The water inlet hole 6 is connected to the water supply mechanism. The right outer wall of the sand box 1 is 20 cm high with 15 water outlet holes 7 with a diameter of 1 cm and connected to the test chamber 5. The top of the sand box 1 is sealed and connected with a cover plate 10 made of organic glass. The thickness of the cover plate 10 is 3 cm. The cover plate 10 is penetrated by 7×5 sampling holes 11 for a total of 35 holes for the extraction and repair mechanism. The aperture of the sampling holes 11 is 1 cm, and the hole spacing is 5 cm. The extraction and repair mechanism includes an extraction outer tube 13, and the top of the extraction outer tube 13 is movably and sealedly penetrated with an extraction inner tube 16. The extraction outer tube 13 is an organic glass tube with a length of 40 cm and a diameter of 1 cm, and the extraction inner tube 16 is an organic glass tube with a length of 40 cm and a diameter of 0.5 cm.

[0023] Specific combination Figure 3 A water storage box 8 is fixedly installed on the outer wall of the sand box 1, and the water outlet holes 7 are connected to the water storage box 8. A drainage hole 9 is penetrated through the bottom of the water storage box 8. The hole diameter of the drainage hole 9 is 1 cm. The drainage hole 9 is connected to the water storage tank 18 through a hose.

[0024] Specific combination Figure 3 In one embodiment of the present invention, the outer wall of the extraction inner tube 16 is sleeved with a rubber sleeve 15 , and the bottom end of the rubber sleeve 15 is located in the top opening of the extraction outer tube 13 .

[0025] Specific combination Figure 3In one embodiment of the present invention, the bottom end of the extraction outer tube 13 is blocked, and a plurality of sieve holes 14 are provided through the bottom end of the outer wall of the extraction outer tube 13. The aperture of the sieve holes 14 is 0.1 cm. The sieve holes 14 are the positions for extracting liquid, and the sampling depth can be controlled.

[0026] Specific combination Figure 1 In one embodiment of the present invention, the extraction and repair mechanism also includes a waste liquid barrel 20, the top opening of the waste liquid barrel 20 is detachably sealed and connected with a barrel cover 21, the barrel cover 21 is connected to a vacuum pump with adjustable vacuum parameters through an exhaust pipe 22, and the barrel cover 21 is connected to the top of the extraction inner tube 16 through a liquid extraction hose 19. By starting the vacuum pump, the air in the waste liquid barrel 20 can be extracted, thereby utilizing negative pressure to draw liquid into the waste liquid barrel 20 through the liquid extraction hose 19 and the extraction inner tube 16.

[0027] In addition, the water supply mechanism includes a peristaltic pump, and a water supply pipe 17 is connected to the peristaltic pump. The water outlet end of the water supply pipe 17 is connected to the water inlet hole 6.

[0028] A rubber plug 12 is installed in the sampling hole 11 .

[0029] Specific combination Figure 5 , in a specific embodiment of the present invention: Medium filling: This implementation scheme configures a mixed medium of 80-120 mesh actual soil: quartz sand = 1:4. The prepared soil medium is fully mixed and filled into the test bin 5: the treated soil medium is filled into the test bin 5 in a layer of 5 cm, and a total of 6 fillings are required. Each time the medium is filled, an electronic balance is used to weigh the medium. When filling, a beaker is used to fill it evenly, and a wooden board is used to compact the soil medium to make it evenly distributed. It is evenly filled to the top of the sand box. After filling, the sand box 1 is covered with a cover plate 10.

[0030] Saturated zone formation: After the soil medium is filled, a peristaltic pump is set to inject pure water into the water distribution bin 4 at an injection flow rate of 100 mL / min. The pure water slowly flows into the test bin 5 after passing through the water distribution hole 3. In this process, the air in the pores of the soil medium in the test bin 5 is completely displaced, and finally a saturated three-dimensional sand box model is formed. After the water level stabilizes, the injection flow rate is reduced to 20 mL / min.

[0031] Pollutant migration and sampling: Prepare 20mL of 100mg / L 1,4-dichlorobenzene solution as the pollutant in this example, and inject the prepared 1,4-dichlorobenzene solution into the test chamber 5 twice with a 10mL syringe. The injection position is Figure 5The marking position is 10cm deep to avoid the upward volatilization of pollutants. No external pressure is added during the whole process. The pollutants migrate freely inside the soil under the action of gravity and water flow. The whole migration process takes about 8 hours. During the migration process, a long syringe is used to monitor the four monitoring points ( Figure 5 Soil solution was sampled at multiple depths (10, 15, 20 cm) at the marked position with sampling times of 0, 1, 2, 4, 6, and 8 h, and the pollutant concentrations of the samples were measured.

[0032] Multiphase extraction remediation and sampling: After the contaminant migration is completed, multiphase extraction remediation begins. Figure 5 Three extraction wells are arranged at the repair point shown (i.e., the extraction outer tube 13 is inserted into the soil medium from the sampling hole 11), the well spacing is about 7.07cm, each extraction outer tube 13 is inserted into the sand box to a depth of 17cm, and the sieve hole 14 is wrapped with gauze to ensure that the soil medium does not block the sand hole 14 during multiphase extraction repair; after connecting the pipeline, the vacuum pump is turned on for extraction, and the vacuum degree parameter of each vacuum pump is 5Kpa, and the repair completion time is 6h. Similarly, sampling is carried out at each depth of the four monitoring points, and at the same time, the waste liquid collected by the three waste liquid barrels 20 is sampled and the volume of the extracted waste liquid is recorded. The sampling time for the extraction repair process is 1, 2, 3, 4, and 6h, and the process and effect of multiphase extraction repair are observed by the concentration of 1,4-dichlorobenzene detected by liquid chromatography.

[0033] Optimization of well layout position and vacuum parameters: By changing the position of each extraction outer tube 13 inserted into the sampling hole 11 on the cover plate 10 and the setting of the vacuum parameters of the vacuum pump, the process parameter setting scheme with the best multiphase extraction and repair effect is explored. Among them, the optional range of the vacuum parameters of each vacuum pump is set to 1-1Kpa, and the optimized layout position of each extraction outer tube 13 can be determined by combining the groundwater simulation software TMVOC with the optimization algorithm constructed by MATLAB.

[0034] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater, characterized by: The invention comprises a water supply mechanism, a sand box (1), and an extraction and repair mechanism. A partition (2) is fixedly installed in the sand box (1), and a surface of the partition (2) is penetrated with a plurality of water distribution holes (3). The partition (2) divides the interior of the sand box (1) into a water distribution bin (4) and a test bin (5). The test bin (5) is used to fill soil medium. A water inlet hole (6) connected to the water distribution bin (4) is penetrated through the outer wall of the sand box (1). The water inlet hole (6) is connected to the water supply mechanism. A plurality of water outlet holes (7) connected to the test bin (5) are penetrated through the outer wall of the sand box (1). A cover plate (10) is sealedly connected to the top of the sand box (1). A plurality of sampling holes (11) for penetrating the extraction and repair mechanism are penetrated through the cover plate (10). The extraction and repair mechanism comprises an extraction outer tube (13). A extraction inner tube (16) is movably and sealedly penetrated through the top of the extraction outer tube (13).

2. A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater according to claim 1, characterized in that: A water storage box (8) is fixedly mounted on the outer wall of the sand box (1), the water outlet holes (7) are all connected to the water storage box (8), a drainage hole (9) is provided through the bottom of the water storage box (8), and the drainage hole (9) is connected to the water storage tank (18) through a hose.

3. A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater according to claim 1, characterized in that: The outer wall of the extraction inner tube (16) is sleeved with a rubber sleeve (15), and the bottom end of the rubber sleeve (15) is located in the top opening of the extraction outer tube (13).

4. A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater according to claim 1, characterized in that: The bottom end of the extraction outer tube (13) is blocked, and a plurality of sieve holes (14) are provided through the bottom end of the outer wall of the extraction outer tube (13).

5. A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater according to claim 1, characterized in that: The extraction and repair mechanism also includes a waste liquid barrel (20), the top opening of the waste liquid barrel (20) is detachably and hermetically connected to a barrel cover (21), the barrel cover (21) is connected to a vacuum pump via an exhaust pipe (22), and the barrel cover (21) is connected to the top of the extraction inner tube (16) via a liquid extraction hose (19).

6. A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater according to claim 1, characterized in that: The water supply mechanism comprises a peristaltic pump, to which a water supply pipe (17) is connected, and a water outlet end of the water supply pipe (17) is in communication with a water inlet hole (6).

7. A three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater according to claim 1, characterized in that: A rubber plug (12) is installed in the sampling hole (11).

8. A method for using a three-dimensional sand box simulation system for multiphase extraction and remediation of soil and groundwater according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Fill the prepared soil medium into the test chamber (5), and install the cover plate (10) on the sand box (1), and each sampling hole (11) on the cover plate (10) is sealed with a rubber plug (12); Step 2: using a peristaltic pump to pump pure water into the water distribution bin (4) through the water supply pipe (17), so that the pure water can exhaust the air in the soil medium, thereby forming a saturated three-dimensional sand box model; Step 3: Select a sampling hole (11) as a pollutant injection point, and use a syringe to inject the configured pollutant into the soil medium from the pollutant injection point multiple times, and do not apply external pressure during the injection process; Step 4: After the injection of the pollutants is completed, the pollutants are allowed to migrate freely in the soil medium under the action of gravity and water flow, and multiple sampling holes (11) are selected near the pollutant injection point as monitoring points. At different times during the migration process, soil solution samples are taken at multiple depths at the monitoring points using a syringe to determine the pollutant concentration of the samples; Step 5: After the migration of pollutants is completed, the pollutant injection point and multiple sampling holes (11) around it are selected as repair points, and an extraction repair mechanism is arranged at the repair point. The vacuum pump is started to perform extraction repair. At different time periods during the extraction repair process, a syringe is used to sample soil solution at multiple depths at the monitoring point, and at the same time, the waste liquid in the waste liquid barrel (20) is sampled and the volume of the extracted waste liquid is recorded. The samples obtained from the monitoring point and the waste liquid barrel (20) are tested to observe the process and effect of multi-phase extraction repair.

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