A system for coupling in-situ enhanced oxidation remediation to a production well that is contaminated with groundwater

Abstract

The present application belongs to the technical field of remediation of groundwater contaminated by industrial enterprises, and particularly relates to a circulating well coupled in-situ enhanced oxidation remediation system for groundwater contaminated by industrial enterprises, which comprises at least one oxidant and dilute sulfuric acid injection unit placed on the ground, a circulating well main unit placed underground, an enhanced oxidation treatment unit, a groundwater extraction unit and an activated carbon adsorption unit placed in the circulating well. The oxidant and dilute sulfuric acid are injected into the bottom of the circulating well, and then the groundwater containing the oxidant at the bottom of the circulating well is extracted to the enhanced oxidation treatment unit by a submersible pump, so that adsorption enrichment and oxidation reaction occur in the unit to remove organic pollutants in the groundwater. The present application utilizes the annular flowing water area formed by the circulating well, and constructs an in-situ enhanced oxidation system by using the granular activated carbon and multi-valence iron ore material built in the circulating well to intensively activate the oxidant, so that the pollution source underground is quickly and efficiently reduced, and the purpose of in-situ remediation of the pollution groundwater with small disturbance on the ground is achieved.

Description

Technical fields:

[0001] This invention belongs to the field of groundwater remediation technology for polluted groundwater in operating enterprises, and specifically relates to a circulating well coupled in-situ enhanced oxidation remediation system for polluted groundwater in operating enterprises. Background technology:

[0002] Finding a technology that can quickly reduce pollution sources, efficiently remediate contaminated groundwater, and not interfere with the normal production activities of operating enterprises and the safety of employees is of paramount importance.

[0003] In recent years, groundwater circulation wells have attracted much attention as an in-situ remediation technology. This technology treats contaminated low-permeability formations by creating a vertical three-dimensional circulation field underground. Crucially, it does not disrupt the normal production activities of operating companies during remediation operations. Therefore, circulation well remediation technology has broad application prospects in contaminated site remediation projects. However, relying solely on circulation well remediation technology is insufficient to achieve the required high efficiency and rapid reduction of pollution sources. Therefore, current circulation well remediation technology is often supplemented with multiphase extraction, but this technology occupies above-ground area and space, affecting the normal operation of operating companies.

[0004] In-situ chemical oxidation remediation (ISCO) technology primarily utilizes various highly oxidizing reactive oxygen species generated by oxidants to chemically react with pollutants in groundwater, thereby purifying the contaminated groundwater. This technology is widely used due to its advantages of minimal secondary pollution and high remediation efficiency.

[0005] Traditional ISCO reagent injection methods result in rapid reagent consumption. Once injection ceases, residual contaminants in the medium are continuously released into the groundwater, leading to contaminant rebound. Furthermore, the catalyst used to activate the oxidant must also be injected into the groundwater. However, the high pH of actual groundwater can easily passivate the added catalyst, hindering its effective activation and reducing the generation efficiency of reactive oxygen species. This results in oxidant waste and low contaminant removal efficiency. Summary of the Invention

[0006] The technical problem this invention aims to solve is to address the shortcomings of single-circulation well remediation technology or in-situ chemical oxidation remediation technology. It proposes a circulating well coupled with in-situ enhanced oxidation remediation system for contaminated groundwater in producing enterprises. This system addresses the limitations of single-circulation well remediation technology in terms of pollutant treatment capacity, low efficiency, and disruption to normal enterprise operations. Simultaneously, it solves problems associated with single in-situ chemical oxidation remediation technology, such as pollutant tailing and rebound, narrow pH application range, and easy catalyst passivation. The goal is to enhance the generation of reactive oxygen species, rapidly reduce underground pollution sources, minimize surface disturbance, and ensure normal enterprise operations and employee safety.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] An in-situ enhanced oxidation remediation system for polluted groundwater in production enterprises using a circulating well coupled with an oxidant and dilute sulfuric acid injection unit located above ground, a circulating well main unit located underground, an enhanced oxidation treatment unit located inside the circulating well, a groundwater extraction unit, and an activated carbon adsorption unit.

[0009] The main unit of the circulation well includes a porous stainless steel filter screen disposed on the side wall of the circulation well, including an upper porous stainless steel filter screen disposed on the upper section side wall of the circulation well and a lower porous stainless steel filter screen disposed on the lower section side wall of the circulation well.

[0010] The oxidant injection unit includes an oxidant storage tank located on the ground for storing an oxidant solution of a certain concentration. The oxidant can be a single or mixed oxidant such as persulfate, perdisulfate, and hydrogen peroxide. An oxidant injection pipe connected to the oxidant storage tank and extending below the circulation well injects oxidant into the contaminated groundwater at the bottom of the circulation well through an oxidant injection nozzle connected to the oxidant injection pipe.

[0011] The dilute sulfuric acid injection unit includes a dilute sulfuric acid storage tank located on the ground for storing a 30wt% dilute sulfuric acid solution. A dilute sulfuric acid injection pipe, connected to the storage tank and extending below the circulation well, injects dilute sulfuric acid into the contaminated groundwater at the bottom of the circulation well through a dilute sulfuric acid injection nozzle connected to the injection pipe. The pH of the groundwater is adjusted to approximately 3.0-4.0 based on the local groundwater quality.

[0012] The enhanced oxidation treatment unit includes a sealed baffle plate located in the lower part of the circulation well to prevent short-circuiting of the water flow. A stainless steel guide plate above the sealed baffle plate is used to evenly distribute the groundwater extracted by the submersible pump. A porous stainless steel cage above the guide plate is filled with granular activated carbon and multivalent iron-based reinforcing filler to enhance the activation of the oxidant and generate active oxygen species, thereby achieving rapid and efficient degradation of pollutants. The reinforcing filler consists of a mixture of granular activated carbon, pyrite, magnetite, and ferrous carbonate, among other multivalent iron-containing ores, in large granular form to ensure no leakage after filling and unobstructed internal hydraulic conditions.

[0013] The groundwater extraction unit includes a submersible pump located below the circulation well and above a porous stainless steel lower filter screen. It is used to pump polluted groundwater containing oxidants from the bottom of the circulation well to the enhanced oxidation treatment unit for adsorption, enrichment, and oxidation reactions, thereby quickly and efficiently removing pollutants from the groundwater.

[0014] The groundwater extraction unit includes a submersible pump located below the circulation well, used to pump groundwater containing oxidants and pollutants from the bottom of the circulation well to the enhanced oxidation treatment unit, where adsorption enrichment and oxidation reactions occur to remove pollutants from the groundwater; it also includes a submersible pump outlet pipe, a submersible pump filter screen, a submersible pump fixing rod, and electrical wires connected to the submersible pump.

[0015] The activated carbon adsorption unit includes a porous stainless steel tank located at the top of the circulation well. The tank is filled with granular activated carbon packing material to adsorb volatile organic compounds that may overflow during the treatment process. The tank is secured to stainless steel supports on both sides below it.

[0016] Furthermore, the upper and lower parts of the porous stainless steel filter screen are also provided with waterproof filler to fill the gap between the circulation well and the circulation well borehole. The waterproof filler is composed of clay filler and dense filler.

[0017] Furthermore, the oxidant injection unit also includes a first control valve, a first flow meter, and a first dosing pump. The first control valve is located below the oxidant tank and is used to control the addition of oxidant; the first flow meter is located downstream of the first control valve and is used to record the injected oxidant flow rate; the first dosing pump is located downstream of the first flow meter and is used to adjust the injected oxidant flow rate; the injection method can be continuous or intermittent. Continuous or intermittent control of oxidant injection at the bottom of the circulating well is achieved through the dosing pump, flow meter, and control valve.

[0018] Furthermore, the dilute sulfuric acid injection unit also includes a second control valve, a second flow meter, and a second dosing pump. The second control valve is located below the dilute sulfuric acid storage tank and controls the addition of dilute sulfuric acid; the second flow meter is located downstream of the second control valve and records the injection flow rate of the dilute sulfuric acid; the second dosing pump is located downstream of the second flow meter and adjusts the injection flow rate of the dilute sulfuric acid; the injection method can be continuous or intermittent. Based on the groundwater quality at the site, the pH of the polluted groundwater in the circulation well area is adjusted to 3.0-4.0 by controlling the flow rate of the second dosing pump.

[0019] Furthermore, the groundwater extraction unit also includes a submersible pump filter connected to the submersible pump to filter out particulate impurities that may be present in the groundwater and prevent clogging of the submersible pump inlet. A submersible pump mounting rod and electrical wires connected to the submersible pump are used to secure the pump and provide power. A submersible pump outlet pipe connected to the submersible pump leads directly to a stainless steel water guide pipe.

[0020] Furthermore, the oxidant injection nozzle and the dilute sulfuric acid injection nozzle in the circulating well are located below the porous stainless steel lower filter screen.

[0021] Furthermore, the granular activated carbon and multivalent iron-based reinforcing filler inside the stainless steel cage are composed of granular activated carbon, pyrite, magnetite, and ferrous carbonate, among other multivalent iron-containing ores, in large granular form to ensure no leakage after filling and unobstructed internal hydraulic conditions. Below the stainless steel cage is a stainless steel water guide plate for uniform water distribution. On both sides below the stainless steel water guide plate are stainless steel water guide plate supports for fixing the plate. A sealing water-proof plate is located below the stainless steel water guide plate, ensuring that all polluted groundwater containing oxidants flows through the reinforcing unit.

[0022] Furthermore, the bottom of the porous stainless steel tank has several circular openings, 1-2 cm in diameter, filled with granular activated carbon filler. The porous stainless steel tank can be lifted out of the ground for replacing the internal granular activated carbon filler. A porous stainless steel tank support is provided below the tank for supporting and fixing it.

[0023] Furthermore, a porous stainless steel filter screen is provided on the circulation well wall, including an upper porous stainless steel filter screen disposed on the upper section of the circulation well wall and a lower porous stainless steel filter screen disposed on the lower section of the circulation well wall. The submersible pump filter screen is located above the lower porous stainless steel filter screen, and the granular activated carbon adsorption unit is located above the upper porous stainless steel filter screen.

[0024] Compared with the prior art, the beneficial effects of the present invention include:

[0025] 1. This invention couples circulating well technology with in-situ chemical oxidation technology, creating a groundwater circulation field through the main unit of the circulating well. It is suitable for the simultaneous remediation of organic pollutants in both saturated and unsaturated zones of groundwater, and has a wide range of applications.

[0026] 2. This invention employs a dilute sulfuric acid injection unit, which injects dilute sulfuric acid into the polluted groundwater below the circulation well to adjust the pH of the groundwater to an acidic environment. This overcomes problems such as catalyst passivation caused by the high pH value of the groundwater, accelerates the generation of reactive oxygen species, and significantly improves the removal efficiency of pollutants.

[0027] 3. This invention involves installing a porous stainless steel cage inside a circulation well, filling the cage with granular activated carbon and multivalent iron-based reinforced filler. The activated carbon adsorbs pollutants, while the iron-based reinforced filler enhances and activates the oxidant to generate reactive oxygen species. As polluted groundwater flows through the porous stainless steel cage, it simultaneously degrades the pollutants. The granular activated carbon and multivalent solid iron-based reinforced filler possess long-lasting catalytic effects.

[0028] 4. This invention employs a controllable oxidant injection unit, which can dynamically adjust the oxidant injection flow rate continuously or intermittently according to the actual groundwater quality conditions, solving problems such as tailing and rebound in pollutant treatment, and significantly improving the utilization rate of oxidant. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the circulating well coupled in-situ enhanced oxidation remediation system for polluted groundwater in a production enterprise according to the present invention.

[0030] Wherein: 1-Oxidant injection unit, 11-Oxidant storage tank, 12-First control valve, 13-First flow meter, 14-First dosing pump, 15-Oxidant injection pipe, 16-Oxidant injection nozzle; 2-Dilute sulfuric acid injection unit, 21-Dilute sulfuric acid storage tank, 22-Second control valve, 23-Second flow meter, 24-Second dosing pump, 25-Dilute sulfuric acid injection pipe, 26-Dilute sulfuric acid injection nozzle; 3-Circulation well unit, 31-Concrete pouring, 32-Waterproof packing, 33-Porous stainless steel upper filter screen, 34-Multi- 35-Sealing cover; 4-Extraction unit; 41-Submersible pump outlet pipe; 42-Submersible pump; 43-Submersible pump filter screen; 44-Submersible pump fixing rod and wire; 5-Enhanced oxidation treatment unit; 51-Stainless steel cage; 52-Granular activated carbon and multivalent iron-based reinforced packing; 53-Stainless steel water guide plate; 54-Stainless steel water guide plate support; 55-Sealing water barrier plate; 6-Activated carbon adsorption unit; 61-Porous stainless steel storage tank; 62-Granular activated carbon packing; 63-Porous stainless steel storage tank support. Detailed Implementation

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments are described in detail. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 An in-situ enhanced oxidation remediation system is coupled to the circulating well for the polluted groundwater of the producing enterprise. The system includes the main circulating well unit 3, whose depth is designed according to the initial laboratory pilot test and field pilot test results and relevant specifications, and determined in combination with the specific site conditions.

[0033] A porous stainless steel upper filter screen 33 and a porous stainless steel lower filter screen 34 are installed on the circulation well 3. The middle position of the porous stainless steel upper filter screen 33 is higher than the lowest groundwater level, and the porous stainless steel lower filter screen 34 is located at the lowest end of the circulation well 3, slightly higher than the submersible pump filter screen 42. The space between the porous stainless steel upper and lower filter screens is filled with dense filler such as concrete, cement, or bentonite to prevent groundwater leakage. The top of the circulation well is sealed with a sealing cap 35.

[0034] The oxidant injection unit 1 includes: an oxidant storage tank 11 installed on the ground, a first control valve 12, a first flow meter 13, a first dosing pump 14, an oxidant injection pipe 15 installed in the circulation well, and an oxidant injection nozzle 16. The end of the oxidant injection pipe is configured with a U-shaped structure, and the oxidant injection nozzle is installed at the end of the oxidant injection pipe with its opening facing upward.

[0035] The dilute sulfuric acid injection unit 2 includes: a dilute sulfuric acid storage tank 21 installed on the ground, a second control valve 22, a second flow meter 23, a second dosing pump 24, a dilute sulfuric acid injection pipe 25 installed in the circulation well, and a dilute sulfuric acid injection nozzle 26. The end of the dilute sulfuric acid injection pipe is configured with a U-shaped structure, and the dilute sulfuric acid injection nozzle is installed at the end of the dilute sulfuric acid injection pipe with its opening facing upward.

[0036] The groundwater extraction unit 4 is located above the porous stainless steel lower filter screen 34 inside the circulation well to ensure smooth water extraction. It includes a submersible pump outlet pipe 41, a submersible pump 42, a submersible pump filter screen 43, and a submersible pump mounting rod and electrical wire 44. The submersible pump filter screen 43, made of stainless steel, is located at the submersible pump inlet and filters impurities that may be present in the groundwater. The submersible pump outlet pipe 41 is connected to a stainless steel water guide plate 53. The submersible pump mounting rod and electrical wire 44, connected to the submersible pump 42, pass through a pre-drilled hole in the sealing cover 35 and extend to the ground. The mounting rod is made of stainless steel with a central hole, and the submersible pump electrical wire passes through the central hole of the mounting rod to supply power to the submersible pump.

[0037] The enhanced oxidation treatment unit 5 includes a stainless steel cage 51, a stainless steel water guide plate 53, and a sealing water-proof plate 55. The stainless steel water guide plate 53 is located directly below the stainless steel cage 51 and is used to evenly distribute the groundwater pumped up by the submersible pump. The sealing water-proof plate 55, located below the stainless steel water guide plate 53, prevents water flow obstruction, ensuring all groundwater flows through the enhanced unit. The internal packing material 52 of the stainless steel cage 51 is composed of multivalent iron ore materials such as granular activated carbon, pyrite, and magnetite. Large-particle iron ore and granular activated carbon are selected to ensure no leakage after filling and unobstructed internal hydraulic conditions. Contaminated groundwater containing oxidants is pumped into the stainless steel cage 51 to undergo a chemical reaction, removing the contaminants it contains.

[0038] During on-site startup, open the second control valve 22 to pre-inject dilute sulfuric acid into the bottom of the circulation well to adjust the pH. Simultaneously, open the circulation well sealing cover 35 and extract a water sample to test whether the pH of the groundwater at the bottom of the circulation well reaches approximately 3.0-4.0. After the pH of the groundwater at the bottom of the circulation well meets the requirements, open the first control valve 12 and the submersible pump 41 to add oxidant and activate the enhanced oxidation treatment unit to remove pollutants. The oxidant and dilute sulfuric acid can be added continuously or intermittently.

[0039] During the above operation, groundwater enters the circulation well through the porous stainless steel lower filter screen 34, is pumped to the upper part of the circulation well by the submersible pump 41, is treated by the enhanced oxidation treatment unit, and then flows into the groundwater area around the circulation well through the porous stainless steel upper filter screen 33, realizing the internal and external circulation of groundwater.

[0040] The technical scope of this invention patent is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention patent, and all such modifications and variations should fall within the protection scope of this invention patent.

Claims

1. A device for in-situ enhanced oxidation remediation of polluted groundwater coupled with circulating wells in a producing enterprise, characterized in that, It includes an oxidant injection unit (1) installed on the ground, a dilute sulfuric acid injection unit (2), a circulation well unit (3) installed inside the underground circulation well borehole, and a groundwater extraction unit (4), an enhanced oxidation treatment unit (5), and an activated carbon adsorption unit (6) installed in the circulation well unit. The oxidant injection unit (1) includes an oxidant storage tank (11) located on the ground for storing an oxidant solution of a certain concentration; an oxidant injection pipe (15) connected to the oxidant storage tank (11) and extending to the bottom of the circulation well, injects oxidant into the polluted groundwater at the bottom of the circulation well through an oxidant injection nozzle (16) connected to the oxidant injection pipe (15); The dilute sulfuric acid injection unit (2) includes a dilute sulfuric acid storage tank (21) located on the ground for storing dilute sulfuric acid solution; a dilute sulfuric acid injection pipe (25) connected to the dilute sulfuric acid storage tank (21) and extending to the bottom of the circulation well, through which dilute sulfuric acid injection nozzles (26) connected to the dilute sulfuric acid injection pipe (25) inject dilute sulfuric acid into the groundwater at the bottom of the circulation well to adjust the pH of the groundwater to 3.0-4.0; The groundwater extraction unit (4) includes a submersible pump (42) placed below the circulation well, which is used to pump the groundwater containing oxidants and pollutants at the bottom of the circulation well to the enhanced oxidation treatment unit (5), where adsorption enrichment and oxidation reactions occur to remove pollutants from the groundwater. The enhanced oxidation treatment unit (5) includes a sealing baffle plate (55) placed in the lower part of the circulation well to prevent water short circuits; a stainless steel water guide plate (53) located above the sealing baffle plate (55) to evenly distribute the groundwater extracted by the submersible pump outlet pipe (41); and a stainless steel cage (51) located above the stainless steel water guide plate (53), which is filled with granular activated carbon and multivalent iron-based reinforced filler (52) to adsorb and enrich pollutants and activate oxidants to generate active oxygen species, thereby achieving the purpose of efficiently degrading pollutants and rapidly reducing pollution sources. The activated carbon adsorption unit (6) includes a porous stainless steel tank (61) located below the top sealing cover (35) of the circulation well, and the porous stainless steel tank (61) is filled with granular activated carbon filler (62) for adsorbing volatile organic compounds that may overflow during the treatment process. The granular activated carbon and multivalent iron-based reinforced filler (52) inside the stainless steel cage (51) are composed of granular activated carbon, pyrite, magnetite and ferrous carbonate multivalent iron-containing ore, and are in the shape of large granules to ensure that there is no leakage after filling and that the internal hydraulic conditions are unobstructed. The porous stainless steel tank (61) has several circular openings at the bottom, with a diameter of 1-2 cm, and is filled with granular activated carbon filler (62). The porous stainless steel tank (61) can be lifted out of the ground for replacing the internal granular activated carbon filler. A porous stainless steel tank support (63) is provided below the porous stainless steel tank (61) for supporting and fixing the tank.

2. The in-situ enhanced oxidation remediation device coupled with a circulating well for polluted groundwater in a producing enterprise as described in claim 1, characterized in that: The groundwater extraction unit (4) also includes a submersible pump outlet pipe (41), a submersible pump filter screen (43), and a submersible pump fixing rod and wires (44) connected to the submersible pump (42).

3. The in-situ enhanced oxidation remediation device coupled with a circulating well for polluted groundwater in a producing enterprise as described in claim 1, characterized in that: The stainless steel water guide plate supports (54) located on both sides below the stainless steel water guide plate (53) in the enhanced oxidation treatment unit (5) are used to fix the stainless steel water guide plate (53).

4. The in-situ enhanced oxidation remediation device coupled with a circulating well for polluted groundwater in a producing enterprise as described in claim 1, characterized in that: In the activated carbon adsorption unit (6), there are porous stainless steel tank supports (63) on both sides below the porous stainless steel tank (61) for supporting and fixing the tank.

5. The in-situ enhanced oxidation remediation device coupled with a circulating well for polluted groundwater in an operating enterprise as described in claim 1, characterized in that: The groundwater circulation well includes at least one submersible pump (42) and submersible pump outlet pipe (41) located below the circulation well; a stainless steel water guide plate (53) and a sealing water baffle plate (55) located inside the circulation well; a stainless steel cage (51) located above the stainless steel water guide plate (53) and filled with granular activated carbon and multivalent iron-based reinforced filler (52); and an activated carbon adsorption unit (6) located below the sealing cover (35) at the top of the circulation well.

6. The in-situ enhanced oxidation remediation device coupled with a circulating well for polluted groundwater in a producing enterprise according to claim 1, characterized in that: The oxidant injection unit (1) also includes a first control valve (12) connected to the oxidant tank (11), a first flow meter (13) connected to the first control valve (12), and a first dosing pump (14).

7. The in-situ enhanced oxidation remediation device coupled with a circulating well for polluted groundwater in a producing enterprise according to claim 1, characterized in that: The dilute sulfuric acid injection unit (2) also includes a second control valve (22) connected to the dilute sulfuric acid storage tank (21), a second flow meter (23) connected to the second control valve (22), and a second dosing pump (24).

8. The in-situ enhanced oxidation remediation device coupled with a circulating well for polluted groundwater in a producing enterprise according to claim 1, characterized in that: A porous stainless steel filter screen is provided on the circulating well wall, including a porous stainless steel upper filter screen (33) provided on the upper section of the circulating well wall and a porous stainless steel lower filter screen (34) provided on the lower section of the circulating well wall; the submersible pump filter screen (43) of the submersible pump (42) is located above the porous stainless steel lower filter screen (34), and the activated carbon adsorption unit (6) is located above the porous stainless steel upper filter screen (33).

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