Contaminated area multiphase extraction and separation system

Abstract

This invention provides a multi-phase extraction and separation system for contaminated land that improves the efficiency of soil organic contamination remediation and contaminant treatment. [Solution] The present invention provides a multiphase extraction and separation system for contaminated land, comprising a solid phase separator a, a gas phase separator b, a NAPL phase separator c, a vacuum extraction equipment d, and a VOC treatment device e, which separates mud and sand containing adsorbed organic matter, gas containing volatile organic matter, water containing dissolved organic matter, light nonaqueous liquid (LNAPL), and heavy nonaqueous liquid (DNAPL). The present invention integrates multiphase extraction and multiphase separation, enabling simultaneous extraction and separation, thereby significantly improving the efficiency of soil organic contamination remediation and contaminant treatment, and is advantageous for the widespread application of the system.

Description

[Technical Field]

[0001] The present invention relates to the technical field of soil remediation for contaminated sites, and specifically to a multi-phase extraction and separation system for contaminated sites. [Background Art]

[0002] With the accelerated advancement of urbanization and the rapid development of the chemical industry, a large amount of organic waste has been generated, and the number of contaminated sites is increasing year by year, so efficient remediation technologies for contaminated sites are needed. Soil organic pollutants are mainly divided into Volatile Organic Compounds (VOC), Dissolved Organic Matter (DOM), adsorbed organic matter and Non-Aqueous Phase Liquids (NAPL), wherein NAPL can be divided into Light Non-Aqueous Phase Liquids (LNAPL) and Dense Non-Aqueous Phase Liquids (DNAPL) according to density. Currently, remediation technologies for contaminated sites mainly include multi-phase extraction, chemical oxidation, solidification and stabilization, biodegradation, etc. Among them, multi-phase extraction technology extracts underground polluted water, gas and NAPL to the ground through a vacuum method to reduce the content of organic pollutants in soil and groundwater. Due to its effect of rapidly controlling underground pollution and achieving simultaneous remediation, multi-phase extraction technology has been widely applied. At present, the development of multi-phase extraction equipment in China is still in an early stage, and existing multi-phase extraction equipment usually can only extract underground pollutants and transport them to hazardous waste treatment institutions, making it difficult to realize on-site separation and treatment at construction sites. [Summary of the Invention] [Problem to be Solved by the Invention]

[0003] In view of the deficiencies of conventional multi-phase extraction devices, the present invention provides a multi-phase extraction and separation system for contaminated sites. [Means for Solving the Problem]

[0004] A contaminated area multiphase extraction and separation system comprising a solid phase separator a, a gas phase separator b, a NAPL phase separator c, a vacuum extraction equipment d, and a VOC treatment device e, wherein, Solid-phase separation apparatus a is used to separate mud and sand containing adsorbed organic matter from the extract, and the extract from which the mud and sand have been separated is transported to gas-phase separation apparatus b. Gas phase separator b is used to separate gas containing volatile organic substances from the extract, and the water and non-aqueous liquid NAPL containing dissolved organic substances are sent by pump to NAPL phase separator c. NAPL phase separation apparatus c is used to separate water and non-aqueous liquid NAPL containing dissolved organic substances into water, light non-aqueous liquid LNAPL, and heavy non-aqueous liquid DNAPL. The vacuum extraction equipment d provides negative pressure to the multiphase extraction process, extracting gas containing volatile organic compounds into the tank of the gas phase separator b. The extracted gas is then purified by the VOC treatment device e and discharged. [Effects of the Invention]

[0005] By adopting the above embodiment, the beneficial effects of the present invention are as follows: 1. The multiphase extraction and separation system for contaminated sites of the present invention integrates multiphase extraction and separation, enabling simultaneous extraction and separation, thereby significantly improving the efficiency of soil organic contamination remediation and contaminant treatment. 2. For the separation of extracts, we developed solid-phase separation equipment, gas-phase separation equipment, and NAPL phase separation equipment to separate mud and sand containing adsorbed organic matter, gas containing volatile organic matter, water containing dissolved organic matter, LNAPL, and DNAPL, thereby facilitating further processing. [Brief explanation of the drawing]

[0006] [Figure 1] This is a schematic diagram of the overall three-dimensional structure of the system of the present invention. [Figure 2] This is a schematic diagram of the system structure decomposition of the present invention. [Figure 3] This is an external view diagram of a single solid-phase separation apparatus. [Figure 4] This is an external view diagram of another solid-phase separation apparatus. [Figure 5] This is an internal diagram of a solid-phase separation apparatus. [Figure 6] This is a diagram showing the configuration of a gas phase separation device. [Figure 7] This is an internal diagram of the NAPL phase separation device. [Figure 8] This is a schematic diagram of the assembly of the rotating structure in the NAPL phase separation apparatus. [Figure 9] This is a cross-sectional view of the rotational structure in an NAPL phase separation apparatus. [Figure 10] This is a schematic diagram of the cross-sectional structure of AA', BB', CC', DD', EE', and FF' in Figure 9. [Figure 11] This is a schematic diagram of the system process flow of the present invention. [Modes for carrying out the invention]

[0007] The technical solution provided in this application will be described in more detail below with reference to specific examples and their drawings. Following the following description will make the advantages and features of this application clearer.

[0008] As shown in Figures 1 to 4, the contaminated area multiphase extraction and separation system includes a solid phase separator a, a gas phase separator b, a NAPL phase separator c, a vacuum extraction equipment d, and a VOC treatment device e, where, Solid-phase separation apparatus a is used to separate mud and sand containing adsorbed organic matter from the extract, and the extract from which the mud and sand have been separated is transported to gas-phase separation apparatus b. Gas phase separator b is used to separate gas containing volatile organic substances from the extract, and the water and non-aqueous liquid (NAPL) containing dissolved organic substances are sent by pump to NAPL phase separator c. NAPL phase separation apparatus c is used to separate water containing dissolved organic substances, light nonaqueous liquid (LNAPL), and heavy nonaqueous liquid (DNAPL). The vacuum extraction equipment d provides negative pressure to the multiphase extraction process, extracting gas containing volatile organic compounds into the tank of the gas phase separator b. The extracted gas is then purified by the VOC treatment device e and discharged.

[0009] The control panel f is connected to the solid-phase separator a, gas-phase separator b, NAPL phase separator c, and vacuum extraction equipment d, enabling automated operation of multi-phase extraction and separation operations.

[0010] The solid-phase separation apparatus a is used to separate mud and sand containing adsorbed organic matter in the extract, and includes an extract inlet a-1, a solid-phase separation equipment casing a-2, a filter screen, a flow meter a-4, an electric control valve, a solid-phase separation liquid level gauge a-6, a fountain pipe a-7, a screw blade a-8, a solid-phase separation motor a-9, a solid-phase separation belt a-10, and a solid-phase separation outlet a-11, as shown in Figures 5-7, where, There are four electrical control valves, designated as the first solid phase separation electrical control valve a-5-1, the second solid phase separation electrical control valve a-5-2, the third solid phase separation electrical control valve a-5-3, and the fourth solid phase separation electrical control valve a-5-4. The first solid phase separation electrical control valve a-5-1 is located at the top of the solid phase separation equipment casing a-2 and is used to regulate the air pressure inside the solid phase separation device. The extract inlet a-1 is located on one side of the solid-phase separation equipment casing a-2 and is in communication with the extract well (not shown). The solid phase separation outlet a-11 is located on the other side of the solid phase separation equipment casing a-2, and a flow meter a-4 and a second solid phase separation electric control valve a-5-2 are located at the tip of the solid phase separation outlet a-11 of the gas phase separation device b. There are four filter screens, numbered a-3-1 (first filter screen), a-3-2 (second filter screen), a-3-3 (third filter screen), and a-3-4 (fourth filter screen) in order of increasing pore size. They are used for multi-stage filtration of mud and sand containing adsorbed organic matter, and are uniformly arranged in order within the solid phase separation equipment casing a-2. The first filter screen a-3-1 is located close to the extract inlet a-1. There are four fountain pipes a-7, positioned behind each filter screen. The four fountain pipes a-7 are connected to an external water source via a third solid phase separation electric control valve a-5-3 and are used to spray water onto the filter screens for cleaning. The screw blade a-8 is arranged at the bottom of the solid-phase separation equipment casing a-2. A fourth solid-phase separation electrically controlled valve a-5-4 for discharging mud and sand is arranged at one end of the screw blade a-8, and the other end of the screw blade a-8 is connected to the output shaft of the solid-phase separation motor a-9 through the solid-phase separation belt a-10. The solid-phase separation motor a-9 provides rotational power to the screw blade a-8 through the solid-phase separation belt a-10, and the rotation of the screw blade a-8 discharges the mud and sand containing washed adsorbed organic matter through the fourth solid-phase separation electrically controlled valve a-5-4. The liquid level gauge a-6 is used for monitoring the liquid level in the solid-phase separation device, and is arranged on the side surface of the solid-phase separation equipment casing a-2.

[0011] Said gas-phase separation device b is used for separating gas containing volatile organic compounds from an extract, and comprises a gas-phase separation inlet b-1, a can body b-2, a gas-phase separation electrically controlled valve b-3, an air pressure sensor b-4, a gas-phase separation liquid level gauge b-5, a gas outlet b-6, a centrifugal pump b-7, a check valve b-8, and a liquid outlet b-9, as shown in Figure 8, wherein The gas-phase separation inlet b-1 and the gas outlet b-6 are arranged at the upper end of the can body b-2, the gas-phase separation inlet b-1 communicates with the solid-phase separation outlet of the solid-phase separation device a, and the gas outlet b-6 communicates with the gas inlet of the vacuum extraction equipment d. The gas-phase separation electrically controlled valve b-3 is arranged at the upper part of the side surface of the can body b-2, and is used for adjusting the air pressure in the can body. The air pressure sensor b-4 is arranged at the upper part of the side surface of the can body b-2, and is used for monitoring the air pressure in the can body. The gas-phase separation liquid level gauge b-5 is arranged on the side surface of the can body b-2, and is used for monitoring the liquid level in the can body. The bottom of the can body b-2 communicates with the inlet of the centrifugal pump b-7 through a pipeline, the outlet of the centrifugal pump b-7 is connected to the liquid outlet b-9, the check valve b-8 is arranged between the outlet of the centrifugal pump b-7 and the liquid outlet b-9, the liquid passes through the check valve b-8 and is discharged from the liquid outlet b-9, the liquid outlet b-9 communicates with the mixed liquid inlet of the NAPL phase separation device c, the centrifugal pump b-7 is used for providing power in the liquid discharge process, and the check valve b-8 is used for preventing liquid backflow.

[0012] Said NAPL phase separation device c is used for separating water containing dissolved organic substances, light non-aqueous phase liquid (LNAPL) and dense non-aqueous phase liquid (DNAPL), it comprises a mixed liquid inlet c-1, an equipment casing c-2, a NAPL phase separation motor c-3, a NAPL phase separation belt c-4, a rotating structure c-5, a separation pipe c-6, a first NAPL phase separation electrically controlled valve c-7-1, a second NAPL phase separation electrically controlled valve c-7-2, a third NAPL phase separation electrically controlled valve c-7-3, a water outlet c-8, an LNAPL outlet c-9, a DNAPL outlet c-10, a first electrode group c-11-1, a second electrode group c-11-2, a third electrode group c-11-3, a first power feeding slip ring c-12-1, a second power feeding slip ring c-12-2, a third power feeding slip ring c-12-3, as shown in Figures 9 to 12, wherein, the mixed liquid inlet c-1 is arranged at the upper end of the rotating structure c-5, the mixed liquid inlet c-1 is in communication with the liquid outlet in the gas phase separation device b, the rotating structure c-5 is arranged inside the equipment casing c-2, the upper part of the rotating structure c-5 is in communication with the mixed liquid inlet c-1, and the lower part thereof is connected to the separation pipe c-6. The rotating structure c-5 is used for mutually separating water containing dissolved organic substances, light non-aqueous phase liquid (LNAPL) and dense non-aqueous phase liquid (DNAPL) through high-speed rotation, and the rotating structure c-5 comprises a bearing c-5-1, a rotating casing c-5-2, a rotating blade c-5-3, a first bottom plate c-5-4, a second bottom plate c-5-5, a third bottom plate c-5-6, a first connection pipe c-5-11, a second connection pipe c-5-12, a third connection pipe c-5-13, grooves are provided on the rotating casing c-5-2 and the first bottom plate c-5-4, the lower part of the rotating blade c-5-3 is engaged into the groove of the first bottom plate c-5-4, and the upper part of the rotating blade c-5-3 is engaged into the groove of the rotating casing c-5-2. Bolts are used to fixedly connect the rotating casing c-5-2, the rotating blade c-5-3, the first bottom plate c-5-4, the second bottom plate c-5-5 and the third bottom plate c-5-6 into an integrated structure, so as to form a centrifugal region inlet and three mutually independent flow channels inside the rotating structure. Two bearings c-5-1 are respectively mounted on the upper side and the lower side of the integrated structure, thus constituting the rotating structure c-5.

[0013] Furthermore, the rotating structure c-5, specifically, The rotating casing c-5-2 has a frustum-shaped structure with a narrower upper part and a wider lower part. A centrifugal region inlet c-5-7 is provided between the top edge of the rotating blade c-5-3 and the rotating casing c-5-2. The rotating blade c-5-3 has a grid structure, with a first channel c-5-8 and a second channel c-5-9 inside, and a third channel c-5-10 is provided between the rotating blade c-5-3 and the side wall of the rotating casing c-5-2. The three channels are interconnected horizontally through the grid of the rotating blade c-5-3. Regarding the details of the first base plate c-5-4, a first circular hole c-5-4-1 is provided in the center, communicating with the first flow path c-5-8 inside the rotating blade c-5-3, an arc-shaped opening c-5-4-2 is provided in the central part, communicating with the second flow path c-5-9 inside the rotating blade c-5-3, and a first circular opening c-5-4-3 is provided at the edge, communicating with the third flow path c-5-10 inside the rotating blade c-5-3. Regarding the details of the second base plate c-5-5, a second circular hole c-5-5-1 is provided in the center, a groove c-5-5-2 is formed around the second circular hole c-5-5-1, the groove c-5-5-2 is relative to and in communication with the arc opening c-5-4-2 of the first base plate c-5-4, and further in communication with the second flow path c-5-9 inside the rotating blade c-5-3, a second circular opening c-5-5-3 is provided at the edge, the second circular opening c-5-5-3 is in communication with the first circular opening c-5-4-3 at the edge of the first base plate c-5-4, and further in communication with the third flow path c-5-10 inside the rotating blade c-5-3, Regarding the details of the third base plate c-5-6, a third circular hole c-5-6-1 is provided in the center, and a rectangular groove c-5-6-2 is opened along the radial direction on the edge of the third circular hole c-5-6-1, and the rectangular groove c-5-6-2 communicates with the second circular opening c-5-5-3 at the edge of the second base plate c-5-5, and further communicates with the third flow path c-5-10 inside the rotating blade c-5-3. The first connecting pipe c-5-11, the second connecting pipe c-5-12, and the third connecting pipe c-5-13 have progressively larger diameters, where the first connecting pipe c-5-11 is connected to the bottom of the first bottom plate c-5-4 and communicates with the first round hole c-5-4-1, the second connecting pipe c-5-12 is connected to the bottom of the second bottom plate c-5-5 and communicates with the second round hole c-5-5-1, and the third connecting pipe c-5-13 is connected to the bottom of the third bottom plate c-5-6 and communicates with the third round hole c-5-6-1. The three connecting pipes described above are fitted in sequence, with gaps between adjacent inner and outer walls, and sealing measures are provided at the connections between the three connecting pipes and the bottom plate. Finally, The first connecting pipe c-5-11 sequentially communicates with the first round hole c-5-4-1 in the center of the first bottom plate c-5-4, and the first flow path c-5-8 inside the rotating blade c-5-3, forming an LNAPL flow path which is a complete flow path for discharging LNAPL. A flow path is formed in the gap between the inner wall of the second connecting pipe c-5-12 and the outer wall of the first connecting pipe c-5-11, and sequentially connects with the second circular hole c-5-1 in the center of the second bottom plate c-5-5, the groove c-5-5-2, the arc-shaped opening c-5-4-2 in the middle of the first bottom plate c-5-4, and the second flow path c-5-9 inside the rotating blade c-5-3, forming a water flow path that is a complete flow path for discharging water containing dissolved organic matter. A flow path is formed in the gap between the inner wall of the third connecting pipe c-5-13 and the outer wall of the second connecting pipe c-5-12, and sequentially connects with the third circular hole c-5-6-1 in the center of the third bottom plate c-5-6, the rectangular groove c-5-6-2, the second circular hole c-5-5-3 on the edge of the second bottom plate c-5-5, the first circular hole c-5-4-3 on the edge of the first bottom plate c-5-4, and the third flow path c-5-10 inside the rotating blade c-5-3, forming a DNAPL flow path which is a complete flow path for discharging DNAPL.

[0014] Separation pipe c-6 includes three passage outlets, each communicating with one of the three complete passages (LNAPL passage, water passage, DNAPL passage) of the rotating structure c-5, and furthermore, separation pipe c-6 outputs from three passages. The LNAPL is discharged downwards via separation pipe c-6, and then discharged from the LNAPL outlet c-9 via the second NAPL phase separation electrical control valve c-7-2. The water containing dissolved organic matter is discharged to the right via separation pipe c-6, and then discharged from water outlet c-8 via the first NAPL phase separation electrical control valve c-7-1. DNAPL is discharged to the left via separation pipe c-6, and then discharged from DNAPL outlet c-10 via third NAPL phase separation electrical control valve c-7-3. The first electrode group c-11-1, the second electrode group c-11-2, and the third electrode group c-11-3 are positioned on the first bottom plate c-5-4, the second bottom plate c-5-5, and the third bottom plate c-5-6, respectively, and are used to measure liquid resistivity and monitor separation purity (LNAPL and DNAPL have high resistivity, while water containing soluble organic matter has low resistivity). The three electrode groups are connected to the three feed slip rings, namely the first feed slip ring c-12-1, the second feed slip ring c-12-1, and the third feed slip ring c-11-3. Power is supplied from the first power supply slip ring c-12-2 and the third power supply slip ring c-12-3. In one embodiment, the first power supply slip ring c-12-1 is positioned between the outer wall of the first connecting pipe c-5-11 and the inner wall of the separation pipe c-6, the second power supply slip ring c-12-2 is positioned between the outer wall of the second connecting pipe c-5-12 and the inner wall of the separation pipe c-6, and the third power supply slip ring c-3 is positioned between the outer wall of the first connecting pipe c-5-13 and the separation pipe c-6. The NAPL phase separation motor c-3 is located inside the equipment casing c-2, and its output shaft is connected to the rotating structure c-5 via the NAPL phase separation belt c-4. The NAPL phase separation motor c-3 supplies power to the rotating structure c-5 via the NAPL phase separation belt c-4.

[0015] The flow separation principle for water and NAPL phase separation is as follows: After water and NAPL enter the rotating structure c-5 through the mixed liquid inlet c-1, the mixed liquid enters the centrifugal region at the bottom of the rotating blade c-5-3 via the centrifugal region inlet c-5-7 at the top edge of the rotating blade c-5-3. The NAPL phase separation motor c-3 provides power to rotate the rotating structure c-5 at high speed. The mixed liquid inside the centrifugal region is driven by the high-speed rotation of the rotating blade c-5-3. Since LNAPL has a lower density than water, the LNAPL in the mixed liquid moves to the rotation axis center c-13, i.e., the LNAPL moves through the grid of the rotating blade c-5-3 to the first channel c-5-8. Similarly, because DNAPL has a higher density than water, the DNAPL in the mixed liquid moves away from the rotation axis center c-13, i.e., LNAPL moves through the lattice of the rotating vane c-5-3 to the third channel c-5-10, and water is located between LNAPL and DNAPL, thereby separating LNAPL, DNAPL and water, in order from the rotation axis center c-13 outward, LNAPL, water, DNAPL, the inclined sidewall of the rotating casing c-5-2 helps DNAPL to accumulate at the outer edge of the bottom of the centrifugal region, and the center of the rotating vane c-5-3 has a conical structure with the cone apex pointing downwards, which helps LNAPL to accumulate at the rotation axis center of the bottom of the centrifugal region. Compared to water, LNAPL and DNAPL have higher resistivity. The resistivity of the LNAPL at its location is monitored through the first electrode group c-11-1. When the resistivity reaches the resistivity setting threshold for separating LNAPL, the second NAPL phase separation electrical control valve c-7-2 opens, and the LNAPL passes through the LNAPL channel and is discharged from the LNAPL outlet c-9. Similarly, the resistivity of DNAPL is monitored through the third electrode group c-11-3. When the resistivity reaches the resistivity setting threshold for separating DNAPL, the third NAPL phase separation electrical control valve c-7-3 opens, and the DNAPL passes through the DNAPL channel and is discharged from the DNAPL outlet c-10. The resistivity of water is monitored by the second electrode group c-11-2. When the resistivity reaches the resistivity setting threshold for separating water, the first NAPL phase separation electrical control valve c-7-1 opens, and the water containing dissolved organic matter passes through the water channel and is discharged from the water outlet c-8.

[0016] The vacuum extraction equipment d provides negative pressure to the multiphase extraction work and includes a gas inlet d-1 and a gas outlet. The gas inlet d-1 communicates with the gas outlet b-6 of the gas phase separator b, and the gas outlet communicates with the VOC treatment device e. Equipment d extracts gas containing volatile organic compounds from the tank b-2 of the gas phase separator b, purifies it in the VOC treatment device e, and discharges it.

[0017] The control panel f enables automated operation of the multiphase extraction and separation process, connects to the solid phase separator a, gas phase separator b, NAPL phase separator c, and vacuum extraction equipment d, acquires information from the flow meter, liquid level gauge, pressure sensor, and electrode group, and controls the operation of the electric control valve, motor, centrifugal pump, and vacuum extraction equipment d. Specifically, The control panel f is connected to the solid phase separation device a, along with its flow meter a-4, solid phase separation liquid level meter a-6, electric control valves (first solid phase separation electric control valve a-5-1, second solid phase separation electric control valve a-5-2, third solid phase separation electric control valve a-5-3, fourth solid phase separation electric control valve a-5-4), and solid phase separation motor a-9. The extraction flow velocity detected by the flow meter a-4 and the liquid level height detected by the solid phase separation liquid level meter a-6 are acquired. The electric control valves and solid phase separation motor a-9 automatically clean the mud and sand on the filter screen. The specific automatic control flow is shown in Figure 13.

[0018] At the start of the extraction process, the control of each electrical control valve and the solid phase separation motor a-9 is as follows: the second solid phase separation electrical control valve a-5-2 is opened, the first solid phase separation electrical control valve a-5-1, the third solid phase separation electrical control valve a-5-3, and the fourth solid phase separation electrical control valve a-5-4 are closed, and the solid phase separation motor a-9 is stopped. At this time, the liquid in the solid phase separation device a is discharged and transported to the gas phase separation device b via the solid phase separation outlet a-11, and the extraction flow rate is monitored via the flow meter a-4.

[0019] During the extraction process, if the extraction flow rate monitored by flow meter a-4 falls below the set flow rate threshold, the washing of the mud and sand on the filter screen will be initiated. The specific washing process is as follows: When the first solid phase separation electric control valve a-5-1 opens, the inside of the solid phase separation device a returns to atmospheric pressure, and water, air, and NAPL continue to slowly enter the gas phase separation device b. The liquid level is monitored through the gas phase separation liquid level gauge a-6, and when the liquid level falls below the solid phase separation liquid level threshold, the second solid phase separation electric control valve a-5-2 closes, and the third solid phase separation electric control valve a-5-3 and the fourth solid phase separation electric control valve a-5-4 open, an external water source passes through the fountain pipe a-7 and sprays water onto the filter screen to wash the mud and sand, and the solid phase separation motor a-9 is operated, and the mud and sand containing adsorbed organic matter are discharged through the screw blade a-8 and the opening of the fourth solid phase separation electric control valve a-5-4. After the washing time reaches the set washing time, the third solid phase separation electric control valve a-5-3 and the fourth solid phase separation electric control valve a-5-4 close, the solid phase separation motor a-9 stops, and the washing process ends. If it is necessary to continue the extraction process after the washing process is complete, the state of each electrical control valve and the solid phase separation motor a-9 is controlled to the state at the start of the extraction process, and the extraction process is continued.

[0020] The control panel f is connected to the gas phase separation device b, specifically the gas phase separation liquid level gauge b-5, pressure sensor b-4, gas phase separation electric control valve b-3, and centrifugal pump b-7. The system acquires pressure data from pressure sensor b-4 and liquid level height detected by gas phase separation liquid level gauge b-5, controls the gas phase separation electric control valve b-3 to adjust the pressure inside tank b-2, and controls the operation of centrifugal pump b-7 to pump the water and NAPL from the tank b-2 to the NAPL phase separation device c. A specific automatic control flow is shown in Figure 14.

[0021] At the start of the extraction operation, the centrifugal pump b-7 stops, the NAPL phase separator c stops, and the liquid level in the tank b-2 is monitored by the gas phase separation liquid level gauge b-5. If the liquid level is higher than the upper limit of the set gas phase separation liquid level range, the NAPL phase separation process is started, the centrifugal pump b-7 is operated, and the NAPL phase separator c is operated synchronously. If the gas phase separation liquid level gauge b-5 observes that the liquid level in the tank b-2 is below the lower limit of the set gas phase separation liquid level range, or if it is necessary to stop the extraction operation, the centrifugal pump b-7 stops, the NAPL phase separator c stops, and the NAPL phase separation process ends.

[0022] The control panel f is connected to the electrode groups of the NAPL phase separator c (first electrode group c-11-1, second electrode group c-11-2, third electrode group c-11-3), electrical control valves (first NAPL phase separation electrical control valve c-7-1, second NAPL phase separation electrical control valve c-7-2, third NAPL phase separation electrical control valve c-7-3), and the NAPL phase separation motor c-3. Resistivity information of the electrode groups is acquired, and the electrical control valves and the NAPL phase separation motor c-3 are controlled to achieve phase separation of water containing dissolved organic matter, light nonaqueous liquid (LNAPL), and heavy nonaqueous liquid (DNAPL). A specific automatic control flow is shown in Figure 15.

[0023] At the start of the NAPL phase separation process, the NAPL phase separation motor c-3 started operation, the first NAPL phase separation electrical control valve c-7-1, the second NAPL phase separation electrical control valve c-7-2, and the third NAPL phase separation electrical control valve c-7-3 closed, and the resistivity was monitored by the first electrode group c-11-1, the second electrode group c-11-2, and the third electrode group c-11-3.

[0024] The resistivity of the LNAPL is monitored by the first electrode group c-11-1, and when the resistivity reaches the set threshold for separating the LNAPL, the second NAPL phase separation electrical control valve c-7-2 opens, and the LNAPL is discharged through the LNAPL outlet c-9. The third electrode group c-11-3 monitors the resistivity of DNAPL, and when the resistivity reaches the set threshold for separating DNAPL, the third NAPL phase separation electrical control valve c-7-3 opens, and the DNAPL is discharged through the DNAPL outlet c-10. The second electrode group c-11-2 monitors the resistivity of the water, and when it reaches the set threshold for resistivity separation, the first NAPL phase separation electrical control valve c-7-1 opens, and the water containing dissolved organic matter is discharged through the water outlet c-8.

[0025] When the NAPL phase separation process is complete, the NAPL phase separation motor c-3 stops operating, and the first NAPL phase separation electrical control valve c-7-1, the second NAPL phase separation electrical control valve c-7-2, and the third NAPL phase separation electrical control valve c-7-3 close.

[0026] The control panel f is connected to the vacuum extraction equipment d and controls the operation of the vacuum extraction equipment. The specific automatic control flow is shown in Figure 16.

[0027] Before starting the extraction process, the extraction negative pressure range is set on the control panel. The pressure is a negative value and includes the lower and upper limits of the atmospheric pressure range. The extraction negative pressure is adjusted by the vacuum extraction equipment d to be lower than the upper limit of the set atmospheric pressure range, and the gas phase separation electric control valve b-3 is adjusted to be higher than the lower limit of the set atmospheric pressure range.

[0028] At the start of the extraction operation, the vacuum extraction equipment d starts operation, the gas phase separation electric control valve b-3 closes, and the pressure sensor b-4 monitors the pressure inside the tank b-2. If the pressure inside the tank b-2 falls below the upper limit of the set pressure range, the vacuum extraction equipment d stops operation. If the pressure inside the tank b-2 falls below the lower limit of the set pressure range, the gas phase separation electric control valve b-3 opens and increases the pressure to exceed the lower limit of the set pressure range. After that, it decides whether to terminate the extraction operation. If the extraction operation is not terminated, the gas phase separation electric control valve b-3 closes, and the pressure sensor b-4 monitors the pressure state inside the tank b-2. If the extraction operation is terminated, the program terminates.

[0029] Furthermore, the control panel is equipped with a touch panel with buttons for setting parameters, starting extraction, and ending extraction, and is used for human-computer interaction.

[0030] The method for using the contaminated site multiphase extraction and separation system described above includes the following steps: Step 1: Install the system and set the parameters using the touch panel on the control panel.

[0031] Step 2: Start the extraction. Clicking the extraction start button on the control panel's touch panel will automatically perform the multiphase extraction and separation process. Once the extraction is complete, the extraction will be stopped.

[0032] Step 3: End the extraction. Clicking the extraction end button on the control panel's touch panel will stop the system from operating and automatically release the extraction negative pressure.

[0033] During application, the extract inlet a-1 of the solid-phase separation device a is connected to the extraction well, and it can be connected to multiple extraction wells simultaneously. The third solid-phase separation electrical control valve a-5-3 is connected to an external water source.

[0034] Before commencing the multiphase extraction and separation operation, the state of each electrical control valve is set as follows: the first solid phase separation electrical control valve a-5-1, the third solid phase separation electrical control valve a-5-3, and the fourth solid phase separation electrical control valve a-5-4 of solid phase separation device a are closed, and the second solid phase separation electrical control valve a-5-2 is open; the gas phase separation electrical control valve b-3 of gas phase separation device b is closed; and the first NAPL phase separation electrical control valve c-7-1, the second NAPL phase separation electrical control valve c-7-2, and the third NAPL phase separation electrical control valve c-7-3 of NAPL phase separation device c are closed.

[0035] Specifically, in step 1, parameters including the extraction negative pressure range (lower limit of the atmospheric pressure range, upper limit of the atmospheric pressure range), flow velocity threshold, solid phase separation liquid level threshold, washing time length, gas phase separation liquid level range (lower limit of the gas phase separation liquid level range, upper limit of the gas phase separation liquid level range), resistivity threshold for separating LNAPL, resistivity threshold for separating DNAPL, and resistivity threshold for separating water are set by controlling the control panel.

[0036] After setting the parameters on control panel f, click the touch panel to start the extraction button, and the system will begin the extraction process. Specifically, step 2 is: 2.1. The vacuum suction equipment d is operated to extract air from the tank b-2 of the gas phase separator b, and once the set suction negative pressure range is reached, the water containing contaminants, air, mud, sand, and NAPL extracts in the well are drawn into the extract inlet a-1 of the solid phase separator a under the action of vacuum pressure.

[0037] 2.2 The extract is filtered in a multi-stage process from the largest to the smallest pore size in solid-phase separation apparatus a (first filter a-3-1, second filter a-3-2, third filter a-3-3, and fourth filter a-3-4, in that order). After filtering, the mud containing adsorbed organic matter remains on the filter, while the water, air, and NAPL enter gas-phase separation apparatus b.

[0038] After the equipment has been running for a certain period of time, the filter screen becomes clogged with mud and sand, making it difficult for water, air, and NAPL to pass through, causing the extraction flow rate to decrease. When the flow meter a-4 detects that the extraction flow rate has fallen below the set flow rate threshold, the automatic cleaning of the mud and sand on the filter screen is initiated.

[0039] 2.3. Water, air, and NAPL containing contaminants enter the gas phase separator b through the gas phase separation inlet b-1. After the water and NAPL are located at the bottom of the boiler b-2, the air at the top is extracted by the vacuum extraction equipment d through the gas outlet b-6 and transported to the VOC treatment device e, where it is purified and then discharged.

[0040] When the gas phase separation level meter b-5 detects that the liquid level in the boiler body b-2 has reached the upper limit of the set gas phase separation level range, the centrifugal pump b-7 and the NAPL phase separator c start operation to separate LNAPL, DNAPL, and water.

[0041] Specifically, in step 3, after the extraction process is completed, the extraction completion button on the control panel f touch panel is clicked to stop the system operation, the gas phase separation electric control valve b-3 is automatically opened, and the inside of the boiler body b-2 is returned to an atmospheric pressure state.

[0042] The above description is intended solely to describe preferred embodiments of the present application and does not imply any limitation of the scope of the present application. Any modifications or alterations made by a general expert in the art based on the technical content disclosed above should be considered equivalent valid embodiments and shall fall within the scope of protection of the present invention. [Explanation of symbols]

[0043] a. Solid-phase separation apparatus; here, a-1, Extract inlet; a-2, Solid phase separation equipment casing; a-3-1, First filter screen; a-3-2, Second filter screen; a-3-3, Third filter screen; a-3-4, Fourth filter screen; a-4, Flow meter; a-5-1, First solid phase separation electric control valve; a-5-2, Second solid phase separation electric control valve; a-5-3, Third solid phase separation electric control valve; a-5-4, Fourth solid phase separation electric control valve; a-6, Solid phase separation liquid level gauge; a-7, Spray pipe; a-8, Screw blade; a-9, Solid phase separation motor; a-10, Solid phase separation belt; a-11, Solid phase separation outlet; b. Gas phase separation apparatus; here, b-1, Gas phase separation inlet; b-2, Gas phase separation tank; b-3, Gas phase separation electric control valve; b-4, Pressure sensor; b-5, Gas phase separation liquid level gauge; b-6, Gas outlet; b-7, Centrifugal pump; b-8, Check valve; b-9, Liquid outlet; c. NAPL phase separation apparatus; here, c-1, Mixed liquid inlet; c-2, Equipment casing; c-3, NAPL phase separation motor; c-4, NAPL phase separation belt; c-5, Rotating structure; c-6, Separation pipe; c-7-1, First NAPL phase separation electric control valve; c-7-2, Second NAPL phase separation electric control valve; c-7-3, Third NAPL phase separation electric control valve; c-8, Water outlet; c-9, LNAPL outlet; c-10, DNAPL outlet; c-11-1, First electrode group; c-11-2, Second electrode group; c-11-3, Third electrode group; c-12-1, First power supply slip ring; c-12-2, Second power supply slip ring; c-12-2, Third power supply slip ring; c-13, Rotation axis center; c-5-1, bearing; c-5-2, rotating casing; c-5-3, rotating blades; c-5-4, first base plate; c-5-4-1, first round hole; c-5-4-2, arc opening; c-5-4-3, first circular opening; c-5-5, second base plate; c-5-5-1, second round hole; c-5-5-2, groove; c-5-5-3, second circular opening; c-5-6, third base plate; c-5-6-1, third round hole; c-5-6-2, rectangular groove; c-5-7, centrifugal region inlet; c-5-8, first flow path; c-5-9, second flow path; c-5-10, third flow path; c-5-11, first connecting pipe; c-5-12, second connecting pipe; c-5-13, third connecting pipe; d. Vacuum extraction equipment; here, d-1, gas inlet; e. VOC treatment device.

Claims

1. It includes a solid-phase separation device (a), a gas-phase separation device (b), a NAPL phase separation device (c), a vacuum extraction device (d), and a VOC treatment device (e), where, The solid-phase separation unit (a) is used to separate mud and sand containing adsorbed organic matter from the extract, and the extract from which the mud and sand have been separated is transported to the gas-phase separation unit (b). The gas phase separator (b) is used to separate the gas containing volatile organic substances from the extract, and the water and non-aqueous liquid NAPL containing the dissolved organic substances are sent by pump to the NAPL phase separator (c). The NAPL phase separation apparatus (c) is used to separate water and non-aqueous liquid NAPL containing dissolved organic matter into water, light non-aqueous liquid LNAPL, and heavy non-aqueous liquid DNAPL. The vacuum extraction equipment (d) provides negative pressure for the multiphase extraction work, extracts gas containing volatile organic compounds into the tank of the gas phase separator (b), and the extracted gas is purified by the VOC treatment device (e) and discharged. The NAPL phase separation apparatus (c) includes a mixed liquid inlet (c-1), equipment casing (c-2), NAPL phase separation motor (c-3), NAPL phase separation belt (c-4), rotating structure (c-5), separation pipe (c-6), first NAPL phase separation electric control valve (c-7-1), second NAPL phase separation electric control valve (c-7-2), third NAPL phase separation electric control valve (c-7-3), water outlet (c-8), LNAPL outlet (c-9), DNAPL outlet (c-10), first electrode group (c-11-1), second electrode group (c-11-2), third electrode group (c-11-3), first power supply slip ring (c-12-1), second power supply slip ring (c-12-2), third power supply slip ring (c-12-3), where, The mixed liquid inlet (c-1) is located at the upper end of the rotating structure (c-5), and the mixed liquid inlet (c-1) communicates with the liquid outlet in the gas phase separator (b). The rotating structure (c-5) is located inside the equipment casing (c-2), and the upper part of the rotating structure (c-5) is in communication with the mixed liquid inlet (c-1), and the lower part is connected to the separation pipe (c-6). The rotating structure (c-5) includes a bearing (c-5-1), a rotating casing (c-5-2), rotating blades (c-5-3), a first bottom plate (c-5-4), a second bottom plate (c-5-5), a third bottom plate (c-5-6), a first connecting pipe (c-5-11), a second connecting pipe (c-5-12), and a third connecting pipe (c-5-13). Grooves are provided in the rotating casing (c-5-2) and the first bottom plate (c-5-4), the lower part of the rotating blade (c-5-3) engages with the groove in the first bottom plate (c-5-4), and the upper part of the rotating blade (c-5-3) engages with the groove in the rotating casing (c-5-2). The rotating casing (c-5-2), rotating blade (c-5-3), first bottom plate (c-5-4), second bottom plate (c-5-5), and third bottom plate (c-5-6) are fixed together as a single structure using bolts, forming a centrifugal region inlet and three independent flow paths inside the rotating structure. Two bearings (c-5-1) are attached to the top and bottom of this single structure, thus forming the rotating structure (c-5). The separation pipe (c-6) outputs from three flow paths. The LNAPL is discharged downwards through the separation pipe (c-6), and then discharged from the LNAPL outlet (c-9) through the second NAPL phase separation electrical control valve (c-7-2). The water containing dissolved organic matter is discharged to the right via the separation pipe (c-6), and then discharged from the water outlet (c-8) via the first NAPL phase separation electrical control valve (c-7-1). DNAPL is discharged to the left via the separation pipe (c-6), and then discharged from the DNAPL outlet (c-10) via the third NAPL phase separation electrical control valve (c-7-3). The first electrode group (c-11-1), the second electrode group (c-11-2), and the third electrode group (c-11-3) are arranged on the first bottom plate (c-5-4), the second bottom plate (c-5-5), and the third bottom plate (c-5-6), respectively, and the three electrode groups are powered by three groups of power supply slip rings, namely the first power supply slip ring (c-12-1), the second power supply slip ring (c-12-2), and the third power supply slip ring (c-12-3). The NAPL phase separation motor (c-3) is located inside the equipment casing (c-2), and the output shaft of the NAPL phase separation motor (c-3) is connected to the rotating structure (c-5) via the NAPL phase separation belt (c-4). The NAPL phase separation motor (c-3) supplies power to the rotating structure (c-5) via the NAPL phase separation belt (c-4). In the aforementioned rotating structure (c-5), The rotating casing (c-5-2) has a frustum-shaped structure that is narrower at the top and wider at the bottom. A centrifugal region inlet (c-5-7) is provided between the top edge of the rotating blade (c-5-3) and the rotating casing (c-5-2). The rotating blade (c-5-3) has a grid structure, with a first flow path (c-5-8) and a second flow path (c-5-9) inside, and a third flow path (c-5-10) between the rotating blade (c-5-3) and the side wall of the rotating casing (c-5-2). The three flow paths are interconnected horizontally through the grid of the rotating blade (c-5-3). Regarding the details of the first base plate (c-5-4), a first circular hole (c-5-4-1) is provided in the center, communicating with the first flow path (c-5-8) inside the rotating blade (c-5-3), an arc-shaped opening (c-5-4-2) is provided in the central part, communicating with the second flow path (c-5-9) inside the rotating blade (c-5-3), and a first circular opening (c-5-4-3) is provided at the edge, communicating with the third flow path (c-5-10) inside the rotating blade (c-5-3). Regarding the details of the second base plate (c-5-5), a second circular hole (c-5-5-1) is provided in the center, and a groove (c-5-5-2) is provided around the second circular hole (c-5-5-1). The groove (c-5-5-2) is relative to and in communication with the arc-shaped opening (c-5-4-2) of the first base plate (c-5-4), and further in communication with the second flow path (c-5-9) inside the rotating blade (c-5-3). A second circular opening (c-5-5-3) is provided at the edge, and the second circular opening (c-5-5-3) is in communication with the first circular opening (c-5-4-3) at the edge of the first base plate (c-5-4), and further in communication with the third flow path (c-5-10) inside the rotating blade (c-5-3). Regarding the details of the third bottom plate (c-5-6), a third circular hole (c-5-6-1) is provided in the center, and a rectangular groove (c-5-6-2) is opened along the radial direction on the edge of the third circular hole (c-5-6-1). The rectangular groove (c-5-6-2) communicates with the second circular opening (c-5-5-3) at the edge of the second bottom plate (c-5-5), and further communicates with the third flow path (c-5-10) inside the rotating blade (c-5-3). The first connecting pipe (c-5-11), the second connecting pipe (c-5-12), and the third connecting pipe (c-5-13) have progressively larger diameters, where the first connecting pipe (c-5-11) is connected to the bottom of the first bottom plate (c-5-4) and communicates with the first round hole (c-5-4-1), the second connecting pipe (c-5-12) is connected to the bottom of the second bottom plate (c-5-5) and communicates with the second round hole (c-5-5-1), and the third connecting pipe (c-5-13) is connected to the bottom of the third bottom plate (c-5-6) and communicates with the third round hole (c-5-6-1). The three connecting pipes, the first connecting pipe (c-5-11), the second connecting pipe (c-5-12), and the third connecting pipe (c-5-13), are fitted in sequence, with gaps between adjacent inner and outer walls, and sealing measures are provided at the connections between the three connecting pipes and the bottom plate, and finally, The first connecting pipe (c-5-11) is sequentially connected to the first round hole (c-5-4-1) in the center of the first bottom plate (c-5-4), and the first flow path (c-5-8) inside the rotating blade (c-5-3), forming an LNAPL flow path which is a complete flow path for discharging LNAPL. A flow path is formed in the gap between the inner wall of the second connecting pipe (c-5-12) and the outer wall of the first connecting pipe (c-5-11), and sequentially connects with the second circular hole (c-5-1) in the center of the second bottom plate (c-5-5), the groove (c-5-5-2), the arc opening (c-5-4-2) in the middle of the first bottom plate (c-5-4), and the second flow path (c-5-9) inside the rotating blade (c-5-3), forming a water flow path that is a complete flow path for discharging water containing dissolved organic matter. A multiphase extraction and separation system for contaminated land, characterized in that a flow path is formed in the gap between the inner wall of the third connecting pipe (c-5-13) and the outer wall of the second connecting pipe (c-5-12), which sequentially communicates with the third circular hole (c-5-6-1) in the center of the third bottom plate (c-5-6), the rectangular groove (c-5-6-2), the second circular hole (c-5-5-3) on the edge of the second bottom plate (c-5-5), the first circular hole (c-5-4-3) on the edge of the first bottom plate (c-5-4), and the third flow path (c-5-10) inside the rotating blade (c-5-3), thereby forming a DNAPL flow path that is a complete flow path for discharging DNAPL.

2. The solid-phase separation apparatus (a) includes an extract inlet (a-1), a solid-phase separation equipment casing (a-2), a filter screen, a flow meter (a-4), an electric control valve, a solid-phase separation liquid level gauge (a-6), a fountain pipe (a-7), a screw blade (a-8), a solid-phase separation motor (a-9), a solid-phase separation belt (a-10), and a solid-phase separation outlet (a-11), where, There are four electrical control valves, designated as the first solid phase separation electrical control valve (a-5-1), the second solid phase separation electrical control valve (a-5-2), the third solid phase separation electrical control valve (a-5-3), and the fourth solid phase separation electrical control valve (a-5-4). The first solid phase separation electrical control valve (a-5-1) is located at the top of the solid phase separation equipment casing (a-2) and is used to regulate the air pressure inside the solid phase separation device. The extract inlet (a-1) is located on one side of the solid-phase separation equipment casing (a-2) and is in communication with the extract well. The solid phase separation outlet (a-11) is located on the other side of the solid phase separation equipment casing (a-2), and a flow meter (a-4) and a second solid phase separation electric control valve (a-5-2) are located at the tip of the solid phase separation outlet of the gas phase separation device (b). There are four filter screens, numbered in descending order of pore size as the first filter screen (a-3-1), the second filter screen (a-3-2), the third filter screen (a-3-3), and the fourth filter screen (a-3-4). They are used for multi-stage filtration of mud and sand containing adsorbed organic matter, and are uniformly arranged in order within the solid phase separation equipment casing (a-2). The first filter screen (a-3-1) is located close to the extract inlet (a-1). There are four fountain pipes (a-7), positioned behind each filter screen. The four fountain pipes (a-7) are connected to an external water source via a third solid-phase separation electric control valve (a-5-3) and are used to spray water onto the filter screens for cleaning. The screw blade (a-8) is positioned at the bottom of the solid phase separation equipment casing (a-2), and a fourth solid phase separation electric control valve (a-5-4) for discharging mud and sand is positioned at one end of the screw blade (a-8), and the other end of the screw blade (a-8) is connected to the output shaft of the solid phase separation motor (a-9) via a solid phase separation belt (a-10), and the solid phase separation motor (a-9) supplies rotational power to the screw blade (a-8) via the solid phase separation belt (a-10), and as the screw blade (a-8) rotates, the mud and sand containing the washed adsorbed organic matter is discharged through the fourth solid phase separation electric control valve (a-5-4). The multiphase extraction and separation system for contaminated land according to claim 1, characterized in that a liquid level gauge (a-6) is used to monitor the liquid level in the solid phase separation device and is located on the side of the solid phase separation equipment casing (a-2).

3. The gas phase separation apparatus (b) includes a gas phase separation inlet (b-1), a boiler (b-2), a gas phase separation electric control valve (b-3), a pressure sensor (b-4), a gas phase separation liquid level gauge (b-5), a gas outlet (b-6), a centrifugal pump (b-7), a check valve (b-8), and a liquid outlet (b-9), where, The gas phase separation inlet (b-1) and gas outlet (b-6) are located at the upper end of the boiler body (b-2), the gas phase separation inlet (b-1) is in communication with the solid phase separation outlet of the solid phase separation device (a), and the gas outlet (b-6) is in communication with the gas inlet of the vacuum extraction equipment (d). The gas phase separation electric control valve (b-3) is located on the upper side of the boiler body (b-2) and is used to regulate the air pressure inside the boiler. The pressure sensor (b-4) is located on the upper side of the can body (b-2) and is used to monitor the air pressure inside the can. The gas-phase separation liquid level gauge (b-5) is positioned on the side of the boiler body (b-2) and is used to monitor the liquid level inside the boiler. The contaminated land multiphase extraction and separation system according to claim 1, characterized in that the bottom of the tank body (b-2) is connected to the inlet of a centrifugal pump (b-7) via piping, the outlet of the centrifugal pump (b-7) is connected to a liquid outlet (b-9), a check valve (b-8) is provided between the outlet of the centrifugal pump (b-7) and the liquid outlet (b-9), the liquid outlet (b-9) is connected to the mixed liquid inlet of a NAPL phase separation device (c), the centrifugal pump (b-7) is used to provide power during the liquid discharge process, and the check valve (b-8) is used to prevent liquid backflow.

4. The multiphase extraction and separation system for contaminated land according to claim 1, characterized in that the vacuum extraction equipment (d) includes a gas inlet (d-1) and a gas outlet, the gas inlet (d-1) is in communication with the gas outlet of a gas phase separation device (b), and the gas outlet is in communication with a VOC treatment device (e).

5. During the extraction process, if the extraction flow rate monitored by the flow meter (a-4) falls below the set flow rate threshold, the washing of the mud and sand on the filter screen is initiated, and the washing process is as follows: When the first solid phase separation electric control valve (a-5-1) opens, the inside of the solid phase separation device (a) returns to atmospheric pressure, and water, air, and NAPL continue to slowly enter the gas phase separation device (b). The liquid level is monitored through the gas phase separation liquid level gauge (a-6), and when the liquid level falls below the solid phase separation liquid level threshold, the second solid phase separation electric control valve (a-5-2) closes, the third solid phase separation electric control valve (a-5-3) and the fourth solid phase separation electric control valve (a-5-4) open, and the external water source passes through the fountain pipe (a-7). The multiphase extraction and separation system for contaminated land according to claim 2, characterized in that water is sprayed onto the filter to wash the mud and sand, a solid phase separation motor (a-9) is operated, mud and sand containing adsorbed organic matter is discharged through the screw blade (a-8) and the opening of the fourth solid phase separation electric control valve (a-5-4), and after the washing time reaches the set washing time, the third solid phase separation electric control valve (a-5-3) and the fourth solid phase separation electric control valve (a-5-4) are closed, the solid phase separation motor (a-9) is stopped, and the washing process is terminated.

6. The multiphase extraction and separation system for contaminated land according to claim 3, characterized in that, at the start of the extraction operation, the centrifugal pump (b-7) is stopped, the NAPL phase separation device (c) is stopped, the liquid level in the tank (b-2) is monitored by the gas phase separation liquid level gauge (b-5), and if the liquid level is higher than the upper limit of the set gas phase separation liquid level range, the NAPL phase separation process is started, the centrifugal pump (b-7) is operated, the NAPL phase separation device (c) is operated synchronously, and if the gas phase separation liquid level gauge (b-5) observes that the liquid level in the tank (b-2) is below the lower limit of the set gas phase separation liquid level range, or if it is necessary to stop the extraction operation, the centrifugal pump (b-7) is stopped, the NAPL phase separation device (c) is stopped, and the NAPL phase separation process is terminated.

7. The LNAPL, DNAPL, and water separation processes are as follows: The NAPL phase separation motor (c-3) is operated to cause the rotating structure (c-5) of the NAPL phase separation apparatus (c) to rotate at high speed. Water and NAPL enter the rotating structure (c-5) through the mixed liquid inlet (c-1), and the mixed liquid enters the centrifugal region below the rotating blades (c-5-3) through the gap at the top edge of the rotating blades (c-5-3). Due to the high-speed rotation, LNAPL, DNAPL, and water are separated, and from the center of the rotation axis outward, they are in the order of LNAPL, water, and DNAPL. The first electrode group (c-11-1) monitors the resistivity of the LNAPL, and when the resistivity reaches the set threshold for separating the LNAPL, the second NAPL phase separation electrical control valve (c-7-2) opens, and the LNAPL is discharged through the LNAPL outlet (c-9). The third electrode group (c-11-3) monitors the resistivity of the DNAPL, and when the resistivity reaches the set threshold for separating the DNAPL, the third NAPL phase separation electrical control valve (c-7-3) opens, and the DNAPL is discharged through the DNAPL outlet (c-10). The multiphase extraction and separation system for contaminated land according to claim 1, characterized in that the resistivity of water is monitored by a second electrode group (c-11-2), and when the resistivity reaches a set threshold for separating the water, the first NAPL phase separation electrical control valve (c-7-1) opens, and the water containing dissolved organic matter is discharged through the water outlet (c-8).

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