Soil remediation device and method

Abstract

The present invention discloses a soil remediation device and method, the device includes a volatile gas capture device, a gas extraction device and an exhaust gas treatment device; the volatile gas capture device is composed of a plurality of horizontal remediation pipes; the method includes a pollution situation survey; forming a remediation protective layer; digging a vertically downward longitudinal side well inside a gas station site away from a traffic road; laying out the horizontal well points, and using the side well as the starting point of drilling, to build a horizontal well toward the pollution source area of ​​the gas station site; turning on the heating resistor rod and the gas extraction device to collect volatile organic pollutants in the horizontal remediation pipe. The method of the present invention can achieve the remediation of the soil below the ground, enhance the thermal conductivity of the soil, quickly remediate groundwater, and cut off the diffusion of pollutants around, while ensuring the normal use of the gas station on the ground. , thereby improving the overall remediation effect of the gas station.

Description

Technical Field

[0001] The present invention relates to the technical field of restoration engineering, and in particular to a soil restoration device and method. Background Art

[0002] Gas stations are mainly used to supply diesel, gasoline and other fuel oils to social vehicles. During long-term use, improper maintenance or material aging may cause oil leakage, which will penetrate into the nearby underground soil and groundwater. The characteristics of gas station sites are different from conventional polluted sites. First, the pollution types are mainly organic pollutants, mainly TPH; second, the pollution range is concentrated in small areas and dispersed in large areas. After leakage, oil substances mainly exist in liquid and gas phases, threatening human health through volatilization and contact.

[0003] According to urban planning, gas stations are generally located at traffic junctions or main streets in cities, so they are not suitable for large-scale destructive repairs. The patent application document with application publication number CN104959373A discloses a repair system method for thermally enhanced multiphase extraction of gas station soil and groundwater. This method achieves thermal enhancement through the design of the well pipe and assists biological ventilation. Its heating system heats during the extraction process and is controlled by a monitoring system. This method intends to achieve the purpose of repairing soil and groundwater by using multiple methods at the same time, but the method is based on the premise that the gas station is abandoned to build a repair device from the ground, or in other words, the repair of the gas station affects the normal operation of the gas station. Obviously, this is inconsistent with the actual needs.

[0004] Therefore, it is necessary to find a repair device and method specifically for the underground soil and groundwater of a gas station without affecting the normal use of the surface layer of the site. Summary of the invention

[0005] The present invention provides a soil remediation device and method, in particular, an in-situ remediation device and method for underground soil and groundwater at a gas station. The device and method can achieve the remediation of the soil below the ground, enhance the thermal conductivity of the soil, quickly remediate the underground soil and groundwater, and cut off the diffusion of pollutants around, thereby improving the overall remediation effect of the gas station, while ensuring the normal use of the ground gas station at the site.

[0006] The specific technical solutions are as follows:

[0007] A soil remediation device, used for in-situ remediation of underground soil and groundwater at a gas station, comprising: a volatile gas capture device, a gas extraction device and an exhaust gas treatment device connected in sequence;

[0008] The volatile gas capture device is composed of a plurality of transverse repair pipes arranged transversely at the underground soil pollution source, each transverse repair pipe being connected to the gas extraction device;

[0009] The transverse repair pipe is an inner and outer double-layer tubular structure, one end of which is an open end and the other end is a sealed end, and a detachable sealing cover is placed on the sealed end; the open end extends into the pollution source area; an air vent is provided on the inner tube body of the transverse repair pipe, and a gas collecting channel is formed between the inner layer and the outer layer; an air outlet hole connected to the gas collecting channel is opened on the sealing cover; a heating resistor rod is also provided on the sealing cover;

[0010] The gas outlet is also connected to the gas extraction device through a pipeline.

[0011] The more special structure of the above-mentioned remediation device is the volatile gas capture device, that is, multiple horizontal remediation pipes are set instead of vertical remediation pipes, and heating resistors are set, which can promote the volatilization of organic pollutants around the soil by heating, and then capture volatile gases. The number and length of the horizontal remediation pipes are determined according to the actual situation of the site.

[0012] Furthermore, the gas extraction device is composed of a gas collecting pipe, an extraction pump and a connecting pipe connected in sequence; the waste gas treatment device is composed of an activated carbon adsorber, a secondary adsorber, an induced draft fan and an exhaust pipe connected in sequence; the gas collecting pipe is connected to the gas outlet, and the connecting pipe is connected to the activated carbon adsorber. The above device can effectively realize the extraction and treatment of gas. In the gas extraction device, multiple gas collecting pipes can correspond to one transverse repair pipe, or a single gas pipe can correspond to a single transverse repair pipe.

[0013] Furthermore, the soil remediation device also includes a gas detection device; the gas detection device includes a gas detector and a temperature detector, 5 cm from the exhaust pipe outlet; during the remediation process, real-time data is collected through the monitor and then the remediation status is analyzed.

[0014] Preferably, the inner diameter of the transverse repair pipe is 30-60 cm, and the outer diameter is 35-65 cm. It has been found through experiments that the transverse repair pipe with the above diameter has the highest efficiency in capturing volatile gases and is the most effective.

[0015] Preferably, the vent holes are round holes arranged in a plum blossom pile shape; the sealing cover is provided with a plurality of air outlet holes in an annular structure, so as to facilitate rapid delivery of volatile gases to the gas extraction device.

[0016] The present invention also provides a method for repairing underground soil and groundwater at a gas station site using the soil repair device, comprising the following steps:

[0017] (1) Investigate the contamination of underground soil and groundwater at the gas station site to be repaired;

[0018] (2) Calcium sulfate is injected downward from the surface of the gas station site, and after curing, a repair and protection layer is formed;

[0019] (3) After the repair and maintenance of the protective layer is completed, a vertical side well is dug vertically downward on the inner side of the gas station site away from the traffic road;

[0020] (4) Layout the horizontal well points according to the survey results of step (1), and use the side well as the starting point of drilling to build horizontal wells toward the pollution source area of ​​the gas station site; install the volatile gas capture device, gas extraction device and exhaust gas treatment device in the in-situ remediation device;

[0021] In the direction vertical to the inner wall of the side well, the horizontal repair pipe without a sealing cover is inserted into the underground soil of the gas station site at different depths and extended to the underground pollution source area of ​​the gas station site; the heating resistance rod is inserted into the soil of the inner layer of the horizontal repair pipe, and the sealing cover is installed;

[0022] (5) Turn on the heating resistor rod, gas extraction device and exhaust gas treatment device to collect volatile organic pollutants in the horizontal repair pipe.

[0023] The present invention first sets up a repair protection layer on the gas station site, and then avoids the normal use site of the gas station site by digging side wells and constructing wells horizontally, and effectively collects and treats volatile pollutants under the gas station site through the design of a specially structured horizontal repair pipe. Under the premise of ensuring the normal use of the ground gas station on the site, the soil below the ground can be repaired, the thermal conductivity of the soil can be enhanced, the groundwater can be quickly repaired, and the surrounding diffusion of pollutants can be cut off, thereby improving the overall repair effect of the gas station.

[0024] The gas extraction device and the waste gas treatment device are placed in the side well.

[0025] Furthermore, in step (1), the physical and chemical properties of the soil at the site, the types of pollutants and the regional distribution of pollution sources at the site are investigated.

[0026] Preferably, in step (2), the depth of the repair protective layer is 15 to 25 cm.

[0027] Furthermore, in step (3), the layout of the lateral well points includes the number, location and depth of the well points.

[0028] It is necessary to investigate the remediation site and the relevant geological parameters of the site, including: the physical and chemical properties of the soil on the site, the type of pollutants, the distribution of the polluted areas on the site, etc. The above geological parameters are used to determine the type of pollutants and the degree of pollution in the site, and to divide the areas with different degrees of pollution; then the layout of the well points, including the number, location and depth of the well points, is carried out according to the current status of the site and the data investigation and analysis. For severely polluted areas, the number of well points can be appropriately increased and the distance between well points can be shortened. For lightly polluted areas, the number of well points can be reduced and the distance between well points can be increased. The site includes soil and groundwater.

[0029] Preferably, in step (3), the side well has a depth of 2 to 4 m, a length of 3 to 6 m, and a width of 1.5 to 3 m, so as to facilitate the installation of the in-situ repair device.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention first sets up a repair protection layer at the gas station site, and then digs side wells and builds wells horizontally, avoiding the normal use site of the gas station site, and effectively collects and treats volatile pollutants under the gas station site through a specially structured horizontal repair pipe design. Under the premise of ensuring the normal use of the ground gas station on the site, the soil below the ground can be repaired, the thermal conductivity of the soil can be enhanced, the underground soil and groundwater can be quickly repaired, and the surrounding diffusion of pollutants can be cut off, thereby improving the overall repair effect of the gas station.

[0032] (2) The present invention expands the scope of use by building a well next to the ground, without affecting the basic performance of the above-ground buildings or the normal operation of oil tanks, etc.

[0033] (3) The present invention uses power to enhance the volatilization of soil organic matter, accelerate the remediation efficiency, and promote the diffusion and migration of pollutants, thereby improving the soil remediation effect.

[0034] (4) The method of the present invention has low construction cost and simple operation, and can be widely used in gas stations and underground contaminated soil within the coverage of existing buildings of similar nature. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the main structure of the soil remediation device in Example 1 and Application Example 1 of the present invention arranged in underground soil;

[0036] Among them, 1. volatile gas capture device; 2. gas extraction device; 3. exhaust gas treatment device; 4. repair protection layer; 5. surface soil; 6. longitudinal side well; 11. transverse repair pipe; 111. open end of transverse repair pipe; 112. sealed end of transverse repair pipe; 113. sealing cover; 114. inner layer of transverse repair pipe; 115. outer layer of transverse repair pipe; 116. air vent; 117. gas collecting channel; 118. air outlet; 119. power supply; 21. gas collecting pipe; 22. extraction pump; 23. connecting pipe; 31. activated carbon adsorber; 32. secondary adsorber; 33. induced draft fan; 34. exhaust pipe.

[0037] Figure 2 for Figure 1 The main view structural schematic diagram is a partial enlarged view of the horizontal repair pipe at position A. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments. The following are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto.

[0039] Example 1

[0040] like Figure 1 and 2 As shown, a soil remediation device, i.e., an in-situ remediation device for underground soil and groundwater at a gas station site, is inserted into the underground soil and is composed of a volatile gas capture device 1, a gas extraction device 2, and an exhaust gas treatment device 3 which are connected in sequence;

[0041] The volatile gas capture device 1 is composed of a plurality of transverse repair pipes 11 arranged transversely at the underground soil pollution source, and each transverse repair pipe is connected to the gas extraction device 2; the transverse repair pipe 11 is an inner and outer double-layer tubular structure, one end is an open end 111, and the other end is a sealed end 112, and a detachable sealing cover 113 is sleeved on the sealed end 112; the sealed end 112 is located in the side well, and the open end 111 is deep into the pollution source area; the inner layer 114 of the transverse repair pipe 11 is provided with a vent hole 116, which is a round hole and is arranged in a plum blossom pile shape. ; The diameter of the inner layer 114 of the transverse repair tube is 30 cm, and the diameter of the outer layer 115 is 40 cm; a gas collecting channel 117 is formed between the inner layer 114 and the outer layer 115; the sealing cover 113 is provided with a plurality of gas outlet holes 118 connected to the gas extraction device 2, and the number of the gas outlet holes 118 is not limited, and they are arranged in a ring shape, and the gas outlet holes 118 are connected to the gas collecting channel 117; a base for placing a heating resistor rod is fixed to the inner side of the sealing cover 113, and an electric wire electrically connected to the base is connected to the outer side of the sealing cover 113, and the other end of the electric wire is connected to a power supply 119.

[0042] The gas extraction device 2 is composed of a gas collecting pipe 21, an extraction pump 22 and a connecting pipe 23 which are connected in sequence; the waste gas treatment device 3 is composed of an activated carbon adsorber 31, a secondary adsorber 32, an induced draft fan 33 and an exhaust pipe 34 which are connected in sequence. The gas collecting pipe 21 is connected to the gas outlet 118, and the connecting pipe 23 is connected to the activated carbon adsorber 31. The above device can effectively realize the extraction and treatment of gas. In the gas extraction device, there can be multiple gas collecting pipes corresponding to one transverse repair pipe, or a single gas pipe corresponding to a single transverse repair pipe. The in-situ repair device also includes a gas detection device; the gas detection device includes a gas detector and a temperature detector, which are installed 5 cm from the exhaust pipe outlet. During the repair process, real-time data is collected by the monitor, and then the repair status is analyzed.

[0043] Application Example 1

[0044] like Figure 1 As shown, a pilot test was conducted at a gas station in Zhejiang Province. The site is located in the suburbs, close to the road and is still in use. The specific steps of the in-situ repair method are as follows:

[0045] (1) Investigate the pollution of underground soil and groundwater at the gas station site to be repaired; determine the test area as 100m 2 The main pollutants on the site are TPH factors such as gasoline and diesel, with a maximum pollutant concentration of 1300 mg / kg, a pollution depth of 2 to 4 m, and a soil permeability coefficient of 4.5×10 -7 m / s.

[0046] (2) Calcium sulfate is injected downward from the surface of the gas station site, and after curing, a repair and protection layer is formed; the density of the point injection is (injection radius is 0.5-1.5m), the depth is 20cm, and after 5 days of curing, a repair and protection layer 4 is formed at a depth of 20cm below the entire gas station site. The repair and protection layer 4 is an air-isolating calcium sulfate layer injected on the surface of the site, which blocks the connection between the ground and the underground, and prevents the diffusion of underground pollutants from affecting the surface of the ground (such as Figure 1 shown).

[0047] (3) After the repair and maintenance of the protective layer is completed, a vertically downward longitudinal side well is dug on the inner side of the gas station site away from the traffic road; the side well is 3.5m deep, 1.2m wide and 5m long.

[0048] (4) According to the survey results of step (1), the horizontal well points are laid out, and the number of horizontal well points is designed to be 4; according to the pollution detection data, the layout elevations of the horizontal wells are set from the ground to the bottom: 2.5m, 3m, 3.5m and 4.5m (the horizontal wells are not arranged in a row in the vertical direction, but are arranged in space). The side wells are used as the starting point of drilling, and horizontal wells are constructed toward the pollution source area of ​​the gas station site; horizontal repair pipes are used for well construction.

[0049] In the direction vertical to the inner wall of the side well, the horizontal repair pipe without a sealing cover is inserted into the underground soil of the gas station site at different depths and extended to the underground pollution source area of ​​the gas station site; the heating resistor rod is inserted into the soil of the inner layer of the horizontal repair pipe, and the sealing cover is installed.

[0050] (5) Turn on the heating resistor and heat continuously for 48 hours, then turn on the gas extraction device and the exhaust gas treatment device to collect volatile organic pollutants in the horizontal repair pipe.

[0051] After 55 days of continuous remediation, sampling and analysis were carried out at the preset monitoring points, and the pollutant removal rate reached 95%, achieving the predetermined remediation target.

Claims

1. A method for repairing underground soil and groundwater at a gas station site using a soil repair device, characterized in that: The soil remediation device comprises: a volatile gas capture device, a gas extraction device and an exhaust gas treatment device which are connected in sequence; The volatile gas capture device is composed of a plurality of transverse repair pipes arranged transversely at the underground soil pollution source, each transverse repair pipe being connected to the gas extraction device; The transverse repair pipe is an inner and outer double-layer tubular structure, one end of which is an open end and the other end is a sealed end, and a detachable sealing cover is placed on the sealed end; the open end extends into the pollution source area; an air vent is provided on the inner tube body of the transverse repair pipe, and a gas collecting channel is formed between the inner layer and the outer layer; an air outlet hole connected to the gas collecting channel is opened on the sealing cover; a heating resistor rod is also provided on the sealing cover; The gas outlet is also connected to the gas extraction device through a pipeline; A method for remediating underground soil and groundwater at a gas station site, comprising the following steps: (1) Investigate the contamination of underground soil and groundwater at the gas station site to be repaired; (2) Calcium sulfate is injected downward from the surface of the gas station site, and after curing, a repair and protection layer is formed; (3) After the repair and maintenance of the protective layer is completed, a vertical side well is dug vertically downward on the inner side of the gas station site away from the traffic road; (4) According to the survey results of step (1), the horizontal well points are laid out, and the side well is used as the starting point of drilling, and the well is constructed horizontally toward the pollution source area of ​​the gas station site; the volatile gas capture device, the gas extraction device and the exhaust gas treatment device are installed; in the direction perpendicular to the inner wall of the side well, the horizontal repair pipe without a sealing cover is inserted into the underground soil of the gas station site at different depths, and extends to the underground pollution source area of ​​the gas station site; the heating resistor rod is inserted into the soil of the inner layer of the horizontal repair pipe, and the sealing cover is installed; (5) Turn on the heating resistor rod, gas extraction device and exhaust gas treatment device to collect volatile organic pollutants in the horizontal repair pipe.

2. The method according to claim 1, characterized in that The gas extraction device is composed of a gas collecting pipe, an extraction pump and a connecting pipe connected in sequence; the waste gas treatment device is composed of an activated carbon adsorber, a secondary adsorber, an induced draft fan and an exhaust pipe connected in sequence; the gas collecting pipe is connected to the air outlet, and the connecting pipe is connected to the activated carbon adsorber.

3. The method according to claim 1, characterized in that It also includes a gas detection device; the gas detection device includes a gas detector and a temperature detector, which are installed at the outlet of the exhaust pipe.

4. The method according to claim 1, characterized in that The inner diameter of the transverse repair pipe is 30 to 60 cm, and the outer diameter is 35 to 65 cm.

5. The method according to claim 1, characterized in that The vent holes are round holes arranged in a plum blossom pile shape; the sealing cover is provided with a plurality of air outlet holes in a ring structure.

6. The method according to claim 1, characterized in that In step (1), the physical and chemical properties of the soil at the site, the types of pollutants, and the regional distribution of pollution sources at the site are investigated.

7. The method according to claim 1, characterized in that In step (2), the depth of the repair protection layer is 15 to 25 cm.

8. The method according to claim 1, characterized in that In step (3), the layout of the lateral well points includes the number, location and depth of the well points.

9. The method according to claim 1, characterized in that In step (3), the side well has a depth of 2 to 4 m, a length of 3 to 6 m, and a width of 1.5 to 3 m.

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