Circulating Well System for Treating VOCs and DNAPLs in Contaminated Groundwater

Abstract

The present invention provides a circulation well system for treating VOCs and DNAPLs in contaminated groundwater. The circulation well pipe is provided with upper and lower sections of permeable sieve holes. The upper section of the permeable sieve holes is a water outlet corresponding to the groundwater level, and the lower section of the permeable sieve holes is a water inlet corresponding to the lower boundary of the groundwater contaminated area. A gas injection pipe is provided in the circulation well pipe, and its lower end extends to the position of the lower section of the permeable sieve holes. A gas phase extraction pipe is provided in the circulation well pipe, which is used to extract the gas containing VOCs escaping from the rising bubbles in the groundwater. A drug injection pipe is installed in the filter material outside the sieve pipe on the upper part of the circulation well pipe, and the bottom of the drug injection pipe is close to the bottom position of the upper section of the permeable sieve holes. The microbial agent in the drug injection pipe is evenly dispersed in the groundwater environment under the action of the circulating water at the drain outlet, so as to avoid the formation of biofilm at the circulation well sieve pipe and blockage, thereby scrapping the multifunctional circulation well unit. A wedge-shaped collector is provided at the bottom of the circulation well water inlet sieve pipe, which can collect DNAPLs in the groundwater.

Description

Technical Field

[0001] The present invention relates to a circulation well system for treating VOCs and DNAPLs in contaminated groundwater. Background Art

[0002] At present, the main technologies for treating contaminated groundwater include ex situ remediation technologies such as extraction and treatment, and in situ remediation technologies such as chemical oxidation and groundwater aeration. The application of these technologies has obvious limitations.

[0003] The groundwater circulation well technology integrates aeration, air lift and air stripping technologies, overcoming the shortcomings of long groundwater extraction and treatment cycle, expensive water treatment fees, small aeration treatment impact radius, low removal rate, and chemical oxidation that easily causes secondary pollution. The circulation well technology is an environmentally friendly technology that has been widely used abroad.

[0004] When groundwater aquifers are polluted by organic matter, there are generally various types of organic matter, typical pollutants are VOCs and DNAPLs, and there is a large gap between their physical and chemical properties and their adsorption performance in the aquifer medium, so they cannot be treated equally, otherwise the remediation effect will be directly affected. Conventional circulation wells can only effectively treat VOCs in the aquifer through aeration, extraction and groundwater circulation, and cannot directly and effectively repair the DNAPLs layer at the bottom of the aquifer, so the overall effect of groundwater remediation is not good.

[0005] Groundwater circulation well technology and microbial treatment technology are often used in the remediation of contaminated groundwater. The coupling of technologies can also significantly improve the efficiency of groundwater remediation and shorten the remediation cycle. Due to the special structural requirements of the multifunctional circulation well, the circulation well pipe needs to be screened up and down and wrapped with a small-diameter screen. The common multifunctional circulation well microbial agent injection pipe is directly set in the well and injected. Due to the high concentration of the near-point injection agent, it is very easy to produce a film attached to the surface of the screen to block the screen pipe, thereby scrapping the circulation well. Summary of the invention

[0006] In view of the above two problems, the purpose of the present invention is to provide a circulation well system for treating VOCs and DNAPLs in contaminated groundwater, which has the characteristics of modularity, intelligence and energy saving, and can smoothly and efficiently treat volatile organic pollutants and DNAPLs in groundwater.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A circulation well system for treating VOCs and DNAPLs in contaminated groundwater, comprising a circulation well pipe, characterized in that:

[0009] The circulation well pipe is provided with two sections of permeable sieve holes, the upper section of which is the water outlet, corresponding to the groundwater level, and the lower section of which is the water inlet, located at the bottom of the circulation well pipe and at the lower boundary of the groundwater contamination area;

[0010] An air injection pipe is provided in the circulation well pipe, and the lower end of the air injection pipe extends to the position of the lower water permeable screen hole;

[0011] A gas phase extraction pipe is provided in the circulation well pipe to extract the gas containing VOCs escaping from the rising bubbles in the groundwater;

[0012] A drug injection pipe is installed in the filler outside the circulating well pipe, and the bottom of the drug injection pipe is close to the bottom position of the upper permeable screen hole;

[0013] A collector is provided below the lower permeable sieve hole in the circulation well pipe to collect DNAPLs flowing in from the water inlet. A DNAPLs recovery pipe is installed in the filler outside the circulation well pipe. The lower end of the DNAPLs recovery pipe is connected to the bottom of the collector, and the upper end is connected to a DNAPLs extraction pump.

[0014] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater, wherein: the bottom of the injection pipe is blocked, and the bottom is screened upward, and the screen opening length is 40%-60% of the distribution length of the upper permeable screen holes of the circulating well pipe.

[0015] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater comprises four injection pipes, which are arranged at equal angles around the circulating well pipe.

[0016] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater, wherein: the collector is a wedge-shaped collector.

[0017] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater, wherein: it also includes an air compressor for providing pressurized gas to the gas injection pipe, and a flow meter and / or a thermometer and / or a pressure gauge are also installed on the downstream pipeline of the air compressor, and the flow meter and / or the thermometer and / or the pressure gauge are connected to the remote central control system.

[0018] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater, wherein: it also includes a biological nutrient source injection unit, which includes a reagent preparation tank, an injection pump and a flow monitor. The injection pump can transport the prepared reagent in the reagent preparation tank to the injection pipe. The stirring motor, injection pump and flow monitor in the reagent preparation tank are all connected to the remote central control system.

[0019] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater, wherein: the upper end of the gas phase extraction pipe is connected to a Roots blower, the downstream of the Roots blower is connected to a gas-liquid separator, the gas phase outlet of the gas-liquid separator is connected to an activated carbon adsorption box, the liquid phase outlet of the gas-liquid separator is connected to a wastewater storage and treatment facility, and the Roots blower is connected to a remote central control system.

[0020] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater, wherein: the DNAPLs extraction pump is connected to a remote central control system.

[0021] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater comprises: a stainless steel wire mesh is wrapped at positions corresponding to two sections of permeable sieve holes on the outside of the circulating well pipe and covered with fillers having permeable and filtering functions, and fillers made of waterproof materials are used at other positions.

[0022] The circulating well system for treating VOCs and DNAPLs in contaminated groundwater, wherein: the outlet end of the DNAPLs extraction pump is connected to the DNAPLs collection tank.

[0023] Compared with the prior art, the present invention has the following beneficial effects: after the microbial agent is discharged into the groundwater through the injection pipe, it is evenly dispersed in the groundwater environment under the action of the circulating water at the outlet. This process can avoid the situation where the agent is directly injected into the circulating well pipe and forms a biofilm attached to the surface of the screen to block the screen pipe, thus avoiding the scrapping of the multifunctional circulating well unit. In addition, the equipment system can directly effectively repair VOCs in the groundwater and the DNAPLs layer at the bottom of the aquifer, so the overall effect of groundwater repair is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the circulation well system for treating VOCs and DNAPLs in contaminated groundwater.

[0025] Figure 2 It is the plan layout of the injection pipe.

[0026] Explanation of the reference numerals: circulating well pipe 1; upper water-permeable sieve hole 2; lower water-permeable sieve hole 3; permeable filler 4; non-permeable filler 5; gas injection pipe 6; aeration head 7; gas phase extraction pipe 8; drug injection pipe 9; wedge collector 10; DNAPLs recovery pipe 11; DNAPLs extraction pump 12; DNAPLs collection tank 13; air compressor 14; flow meter 15; valve 16; drug preparation tank 17; drug injection pump 18; flow monitoring meter 19; valve 20; Roots blower 21; activated carbon adsorption box 22. DETAILED DESCRIPTION

[0027] like Figure 1As shown, the present invention provides a circulation well system for treating VOCs and DNAPLs in contaminated groundwater, which mainly includes a multifunctional circulation well unit, an AS gas source unit, a biological nutrient source injection unit, an exhaust gas extraction and treatment unit and a remote central control system.

[0028] (1) Multifunctional circulation well unit

[0029] The multifunctional circulation well unit mainly includes a circulation well pipe 1, which is usually made of stainless steel pipe with a diameter of 100mm~200mm. The circulation well pipe 1 is provided with two sections of permeable sieve holes, the upper section of which is the outlet, and the middle position of which is flush with the groundwater level. The lower section of which is the inlet, is located at the bottom of the circulation well pipe 1 and at the lower boundary of the groundwater pollution area. The opening length of the inlet is generally 1 / 8 of the thickness of the aquifer, and the opening length of the outlet is generally 1.5 times the opening length of the inlet. A stainless steel wire mesh is provided at the position corresponding to each permeable sieve hole on the outside of the circulation well pipe 1, and then covered with gravel and quartz sand with a suitable ratio as filler (permeable filler 4), which plays the role of water permeability and filtering fine particles. Other positions use fillers made of water-proof materials (non-permeable fillers 5), such as clay or concrete.

[0030] An air injection pipe 6 is provided in the circulation well pipe 1. The lower end of the air injection pipe 6 extends to the position of the lower water-permeable sieve hole 3 and is installed with an aeration head 7 for injecting pressurized gas into the well water.

[0031] A gas phase extraction pipe 8 is provided in the circulation well pipe 1 for extracting the gas containing VOCs escaping from the rising bubbles in the groundwater in the circulation well pipe 1, so as to prevent the volatilized pollutants in the groundwater from causing secondary pollution.

[0032] An injection tube 9 is installed in the filler outside the circulation well pipe 1, and the bottom of the injection tube 9 is flush with the bottom of the upper permeable sieve hole 2. The bottom of the injection tube 9 is blocked and screened, and the screen opening length is 40%-60% of the distribution length of the upper permeable sieve holes 2, so that the microbial agent can be discharged into the groundwater and evenly dispersed in the groundwater environment under the action of the circulating water at the outlet. This process can avoid the situation where the agent is directly injected into the circulation well pipe 1 to form a biofilm attached to the surface of the screen to block the screen pipe, thereby avoiding the scrapping of the multifunctional circulation well unit. In a preferred embodiment, Figure 2 As shown, there are four injection pipes 9 , which are arranged around the circulation well pipe 1 at equal angles.

[0033] A wedge-shaped collector 10 is provided below the lower permeable sieve hole 3. The side height of the wedge-shaped collector 10 is about 100 mm and the angle is about 30°, which can smoothly collect DNAPLs flowing in from the water inlet. A DNAPLs recovery pipe 11 is installed in the filler outside the circulation well pipe 1. The lower end position of the DNAPLs recovery pipe 11 corresponds to the position of the wedge-shaped collector 10, and the upper end is connected to the DNAPLs collection tank 13 through a matching DNAPLs extraction pump 12, so as to extract the DNAPLs in the wedge-shaped collector 10 and pump the DNAPLs to the ground for centralized treatment. This process can effectively solve the problem of collecting and treating DNAPLs at the bottom of the aquifer.

[0034] (2) AS air source unit

[0035] The AS gas source unit is mainly composed of an air compressor 14, a filter, a monitoring device (flow, temperature and pressure monitoring) and other parts. The main equipment of the unit is the air compressor 14, which is the power equipment of the circulation well. Its pressure is generally 0.1~1MPa, and the gas injection flow rate is determined according to the thickness of the aquifer, the spacing between the circulation wells and other parameters. A filter, a flow meter 15 and a valve 16 are installed in sequence on the downstream pipeline of the air compressor 14, and then connected to the upper end of the gas injection pipe 6; a thermometer and / or a pressure gauge can also be installed on the downstream pipeline of the air compressor 14. The monitoring device composed of the flow meter 15 and / or the thermometer and / or the pressure gauge is connected to a remote central control system (not shown in the figure). The remote central control system can adjust the operating parameters such as the gas injection flow and pressure of the air compressor 14 according to the detection signal.

[0036] (3) Biological nutrient source injection unit

[0037] The biological nutrient source injection unit mainly includes devices such as a reagent preparation tank 17, a drug injection pump 18 and a flow monitor 19. The prepared reagent in the reagent preparation tank 17 is connected to the injection pipe 9 through the drug injection pump 18, the flow monitor 19 and the valve 20, and then enters the groundwater for microbial technology enhanced remediation. The stirring motor, the drug injection pump 18 and the flow monitor 19 in the reagent preparation tank 17 are connected to the remote central control system, which can realize remote control of the equipment operation frequency and the like.

[0038] (4) Exhaust gas extraction and treatment unit

[0039] The unit is mainly composed of Roots blower 21, activated carbon adsorption box 22 and DNAPLs collection tank 13. The polluted gas generated in the circulation well is extracted by Roots blower 21, and separated from the gas and water by gas-liquid separator (not shown). The separated polluted gas is transported to the activated carbon adsorption box 22 for treatment, and the separated liquefied polluted water enters the wastewater storage and treatment facilities for treatment. In addition, the DNAPLs in the collector at the bottom of the circulation well are extracted to the DNAPLs collection tank 13 by the DNAPLs extraction pump 12 for centralized treatment. The key equipment in this unit, such as Roots blower 21 and DNAPLs extraction pump 12, and monitoring devices such as flow meter, pressure gauge and VOCs online detector, are all connected to the remote central control system to realize remote monitoring and control of the equipment.

[0040] (5) Remote central control system

[0041] The remote central control system uses PLC equipment and GPRS modules to remotely control the start, stop and frequency conversion of key equipment such as air compressor 14, extraction fan, injection pump 18 and DNAPLs extraction pump 12. Wireless remote transmission is used for on-site monitoring data transmission. A wireless module is added to the existing PLC equipment, and a wireless remote transmission platform is built to monitor environmental data. The multi-functional vortex flowmeter (pressure and flow), groundwater pressure measuring tube, pH probe and saturated dissolved oxygen monitoring probe installed on the ground are connected to the PLC device, and the site-related data is collected to the upper computer configuration software in the central control room for real-time display and storage. The upper computer configuration software can also alarm abnormal data and operations, prompting management personnel to carry out maintenance in time.

[0042] The above description is only illustrative rather than restrictive of the present invention. Those skilled in the art will understand that many modifications, changes or equivalents may be made without departing from the spirit and scope defined by the claims, but all will fall within the scope of protection of the present invention.

Claims

1. A circulation well system for treating VOCs and DNAPLs in contaminated groundwater, comprising a circulation well pipe, characterized in that: The circulation well pipe is provided with two sections of permeable sieve holes, the upper section of which is the water outlet, corresponding to the groundwater level, and the lower section of which is the water inlet, located at the bottom of the circulation well pipe and at the lower boundary of the groundwater contamination area; An air injection pipe is provided in the circulation well pipe, and the lower end of the air injection pipe extends to the position of the lower water permeable screen hole; A gas phase extraction pipe is provided in the circulation well pipe to extract the gas containing VOCs escaping from the rising bubbles in the groundwater; A drug injection pipe is installed in the filler outside the circulating well pipe, and the bottom of the drug injection pipe is close to the bottom position of the upper permeable screen hole; A collector is provided in the circulation well pipe below the lower permeable sieve hole to collect DNAPLs flowing in from the water inlet. A DNAPLs recovery pipe is installed in the filler outside the circulation well pipe. The lower end of the DNAPLs recovery pipe is connected to the bottom of the collector, and the upper end is connected to a DNAPLs extraction pump. The bottom of the injection pipe is blocked and screened upward from the bottom. The screen length is 40%-60% of the distribution length of the upper permeable screen holes of the circulating well pipe. There are four injection pipes, which are arranged around the circulation well pipe at equal angles. Wherein, the collector is a wedge-shaped collector.

2. The circulating well system for treating VOCs and DNAPLs in contaminated groundwater according to claim 1, characterized in that: It also includes an air compressor for providing pressurized gas to the gas injection pipe. A flow meter and / or a thermometer and / or a pressure gauge are installed on the downstream pipeline of the air compressor, and the flow meter and / or the thermometer and / or the pressure gauge are connected to the remote central control system.

3. The circulating well system for treating VOCs and DNAPLs in contaminated groundwater according to claim 1, characterized in that: It also includes a biological nutrient source injection unit, which includes a medicine preparation tank, an injection pump and a flow monitor. The injection pump can transport the prepared medicine in the medicine preparation tank to the injection pipe. The stirring motor, injection pump and flow monitor in the medicine preparation tank are all connected to the remote central control system.

4. The circulating well system for treating VOCs and DNAPLs in contaminated groundwater according to claim 1, characterized in that: The upper end of the gas phase extraction pipe is connected to a Roots blower, the downstream of the Roots blower is connected to a gas-liquid separator, the gas phase outlet of the gas-liquid separator is connected to an activated carbon adsorption box, the liquid phase outlet of the gas-liquid separator is connected to a wastewater storage and treatment facility, and the Roots blower is connected to a remote central control system.

5. The circulating well system for treating VOCs and DNAPLs in contaminated groundwater according to claim 1, characterized in that: The DNAPLs extraction pump is connected to a remote central control system.

6. The circulating well system for treating VOCs and DNAPLs in contaminated groundwater according to claim 1, characterized in that: The positions on the outside of the circulation well pipe corresponding to the two sections of permeable sieve holes are wrapped with a stainless steel wire mesh and covered with fillers with permeable and filtering functions, and fillers made of waterproof materials are used in other positions.

7. The circulating well system for treating VOCs and DNAPLs in contaminated groundwater according to claim 1, characterized in that: The outlet of the DNAPLs extraction pump is connected to the DNAPLs collection tank.

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