Composite underground water remediation system and method for treating petroleum hydrocarbon pollution

Abstract

The invention relates to a composite groundwater remediation system and method for treating petroleum hydrocarbon pollution, and the system comprises a groundwater extraction well and a groundwater recharge well which are arranged in a groundwater petroleum hydrocarbon polluted area, and the groundwater extraction well is surrounded by a permeable reactive barrier; a pressurizing water suction pump, a gas-liquid separator, a mixed reaction tank and an adjusting tank which are sequentially communicated through pipelines are arranged on the ground of the area where underground water is polluted by petroleum hydrocarbon, a chemical adding tank used for adding treatment chemicals into the mixed reaction tank is arranged near the mixed reaction tank, and the pressurizing water suction pump pumps water in the underground water extraction well and pumps the water to the gas-liquid separator. And the water treated by the gas-liquid separator is sequentially treated in the mixed reaction tank and the regulating tank and then is conveyed back to the underground water recharge well. The method has the advantages of large treatment capacity and high efficiency, ensures removal of petroleum hydrocarbon pollutants in underground water, and also can reduce secondary pollution of chemical reaction byproducts to the environment at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of groundwater remediation, and in particular relates to a composite groundwater remediation system and method for treating petroleum hydrocarbon pollution. Background Art

[0002] With the rapid development of the oil industry, oil spills, sudden leaks and unreasonable discharge of oily wastewater have occurred in various links of oil exploration and development, such as drilling engineering construction, oil production, processing, transportation, storage and chemical production, leading to the contamination of groundwater systems by petroleum hydrocarbons. Most organic substances in petroleum hydrocarbons have risks such as carcinogenicity and teratogenicity to humans, which greatly endangers human health.

[0003] Take an irrigation area in northeast China as an example. The middle and upper reaches of the irrigation area have been affected by petroleum pollutants from nearby oil refineries. Pollutants such as aromatic hydrocarbons, volatile phenols, and heavy metals in the soil and groundwater environment of the irrigation area are all above the standard. In addition, the floating oily wastewater adhered to the surface is repeatedly used in agricultural cultivation, which increases the oil content of the cultivated layer. Soluble petroleum hydrocarbon pollutants penetrate into the underground aquifer, causing it to be seriously polluted by petroleum hydrocarbons.

[0004] More and more environmental protection workers at home and abroad have realized the necessity and urgency of treating petroleum-contaminated groundwater. How to remove petroleum hydrocarbon pollutants in groundwater economically, quickly and effectively has become a focus issue that has received great attention. Summary of the invention

[0005] The present invention provides a composite groundwater remediation system and method for treating petroleum hydrocarbon pollution, aiming to overcome the deficiency of the prior art in lacking effective technology for removing petroleum hydrocarbon pollutants in groundwater.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a composite groundwater remediation system for treating petroleum hydrocarbon pollution, comprising a groundwater extraction well and a groundwater reinjection well arranged in an area where groundwater is contaminated by petroleum hydrocarbons, the groundwater extraction well being surrounded by a permeable reaction wall, and a pressurized water pump, a gas-liquid separator, a mixing reaction tank and a regulating tank connected in sequence through pipelines are arranged on the ground of the area where groundwater is contaminated by petroleum hydrocarbons, a dosing tank for adding treatment agents to the mixing reaction tank is arranged near the mixing reaction tank, the pressurized water pump extracts water from the groundwater extraction well and pumps it to the gas-liquid separator, and the water treated by the gas-liquid separator is sequentially treated in the mixing reaction tank and the regulating tank and then returned to the groundwater reinjection well.

[0007] On the basis of the above technical solutions, the present invention can also have the following further specific options.

[0008] Furthermore, the filling medium of the permeable reaction wall is composed of the following raw materials in percentage by mass: 10-12% activated carbon, 20-25% calcium peroxide, 8-12% iron powder, 25-35% sodium silicate and 28-32% binder.

[0009] Furthermore, it also includes a volatile organic compound removal device, and the air inlet of the volatile organic compound removal device is connected to the gas outlet of the gas-liquid separator.

[0010] Furthermore, the volatile organic compound removal device includes an adsorption mechanism, a desorption mechanism and a concentrated gas processing mechanism, the adsorption mechanism includes a plurality of adsorption towers connected in series or in parallel, adsorbents are distributed in the adsorption towers, the desorption mechanism includes a hot air blower, and the concentrated gas processing mechanism includes a burner and / or a condenser.

[0011] Furthermore, the treatment agents added by the dosing tank to the mixed reaction tank are sodium persulfate and ferrous sulfate, and the concentration of sodium persulfate in the liquid in the mixed reaction tank is controlled to be 450-550 mg / L, and the concentration of ferrous sulfate is controlled to be 45-55 mg / L.

[0012] Furthermore, the concentration ratio of the sodium persulfate to the sodium sulfate is 10:1.

[0013] Furthermore, the number of the groundwater recharge wells is set to be multiple, and the distance between adjacent groundwater recharge wells is 5-10m.

[0014] Furthermore, it also includes an external drainage pump, and the water in the regulating pool is pumped out by the external drainage pump and sent into the groundwater recharge well.

[0015] Furthermore, the distance between the groundwater extraction well and the groundwater recharge well is more than 200m.

[0016] The present invention also provides a composite groundwater remediation method for treating petroleum hydrocarbon pollution, which uses the above-mentioned remediation system to perform groundwater remediation treatment, including the following contents:

[0017] S1. Groundwater contaminated by petroleum hydrocarbons first penetrates into the groundwater extraction well through the permeable reaction wall. During the process, some pollutants are removed by degradation, adsorption or precipitation of the filling medium of the permeable reaction wall;

[0018] S2. Start the pressurized water pump to pump the water in the groundwater extraction well into the gas-liquid separator after pressurization. In the gas-liquid separator, the groundwater releases pressure to form dense bubbles, and the volatile organic matter floats up with the bubbles and is discharged to the outside of the gas-liquid separator and is harmlessly treated by the volatile organic matter removal device;

[0019] S3. The liquid in the gas-liquid separator is discharged into the mixed reaction tank, and sodium persulfate and ferrous sulfate are added to the mixed reaction tank from the refueling tank. The concentration of sodium persulfate in the liquid in the mixed reaction tank is controlled to be 450-550 mg / L, and the concentration of ferrous sulfate is controlled to be 45-55 mg / L. The concentration ratio of the sodium persulfate to the sodium sulfate is 10:1. After the addition is completed, the reaction is fully stirred;

[0020] S4. After the liquid in the mixing reaction tank fully reacts, it is discharged into the regulating tank. The regulating tank adjusts the pH and oxygen content of the liquid, and then it is discharged to the groundwater recharge well. The above process continues until it is detected that the groundwater pumped by the pressurized water pump meets the standards.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention treats groundwater contaminated by petroleum hydrocarbons through a petroleum hydrocarbon contaminated composite groundwater remediation system and method formed by combining a permeable wall, a gas-liquid separator and a mixed reaction tank (persulfate advanced oxidation). The system has the advantages of large processing capacity and high efficiency, ensuring the removal of petroleum hydrocarbon pollutants in groundwater while reducing secondary pollution to the environment by by-products of reagent reactions. In addition, during the treatment process, petroleum hydrocarbon pollutants are basically converted into harmless carbon dioxide or water, which is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a composite groundwater remediation system for treating petroleum hydrocarbon pollution provided by the present invention.

[0024] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0025] 1. Permeable wall; 2. Groundwater extraction well; 3. Pressurized water pump; 4. Gas-liquid separator; 5. Dosing tank; 6. Mixing reaction tank; 7. Regulating tank; 8. Groundwater recharge well. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below in conjunction with the accompanying drawings and specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0027] In the description of the present invention, if terms indicating orientation such as "up", "down", "left", "right", "top", "bottom", "inside" and "outside" are used, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] like Figure 1As shown, the present invention provides a composite groundwater remediation system for treating petroleum hydrocarbon pollution, which includes a groundwater extraction well 2 and a groundwater recharge well 8 arranged in an area where groundwater is contaminated by petroleum hydrocarbons, wherein the periphery and bottom of the groundwater extraction well 2 are surrounded by a permeable reaction wall, and the ground in the area where groundwater is contaminated by petroleum hydrocarbons is provided with a pressurized water pump 3, a gas-liquid separator 4, a mixing reaction tank 6 and a regulating tank 7 which are sequentially connected through pipelines, and a dosing tank 5 for adding a treatment agent to the mixing reaction tank 6 is provided near the mixing reaction tank 6, and the pressurized water pump 3 extracts water from the groundwater extraction well 2 and pumps it to the gas-liquid separator 4, and the water treated by the gas-liquid separator 4 is sequentially treated in the mixing reaction tank 6 and the regulating tank 7 and then returned to the groundwater recharge well 8.

[0029] It should be noted that the arrangement and use of the permeable reaction wall are well known to those skilled in the art and will not be described in detail here. The pressure pump can extract the water in the groundwater extraction well and increase the pressure as much as possible so that it can suddenly release the pressure when entering the gas-liquid separator and release more volatile organic matter (gas), thereby removing more harmful organic matter at the gas-liquid separator.

[0030] In one embodiment of the present invention, the filling medium of the permeable reaction wall is composed of the following raw materials in the following mass percentages: 10-12% activated carbon, 20-25% calcium peroxide, 8-12% iron powder, 25-35% sodium silicate and 28-32% binder.

[0031] Preferably, the filling medium is mainly composed of 10% activated carbon, 20% calcium peroxide, 10% iron powder, 30% sodium silicate and 30% adhesive. When groundwater penetrates into the groundwater extraction well through the filling medium, part of the pollutants will react with the filling medium, undergo physical and chemical reactions, and be degraded, adsorbed or precipitated and removed.

[0032] In one embodiment of the present invention, the repair system further comprises a volatile organic compound removal device, and the air inlet of the volatile organic compound removal device is connected to the gas outlet of the gas-liquid separator 4 .

[0033] In one embodiment of the present invention, the volatile organic compound removal device includes an adsorption mechanism, a desorption mechanism and a concentrated gas processing mechanism, the adsorption mechanism includes a plurality of adsorption towers connected in series or in parallel, adsorbents are distributed in the adsorption towers, the desorption mechanism includes a hot air blower, and the concentrated gas processing mechanism includes a burner and / or a condenser.

[0034] It should be noted that the volatile organic compound removal device is well known to those skilled in the art. Taking the adsorption tower as an example, its material can be carbon steel or stainless steel, which is selected according to the corrosiveness of the exhaust gas. The internal structure design should ensure that the exhaust gas is evenly distributed in the adsorbent bed, such as using a gas distribution plate, a guide device, etc. The size of the adsorption tower is determined according to the processing air volume and the adsorbent filling amount. For example, the processing air volume is 20000m 3 / h adsorption tower may have a diameter of 3-4m and a height of 5-8m. Common adsorbents include activated carbon, activated carbon fiber, molecular sieve, etc. Activated carbon has a large specific surface area and rich microporous structure, and has good adsorption performance for a variety of VOCs; activated carbon fiber has a larger specific surface area and fast adsorption and desorption rates; molecular sieve has a specific pore structure and has good selective adsorption capacity for VOCs of certain specific molecular sizes. The filling amount of the adsorbent is calculated and determined based on factors such as the concentration of VOCs in the exhaust gas, the adsorption capacity of the adsorbent, and the size of the adsorption tower. Generally, 0.3-0.6t of adsorbent is filled per cubic meter of adsorption tower volume.

[0035] In one embodiment of the present invention, the treatment agents added by the dosing tank 5 to the mixed reaction tank 6 are sodium persulfate and ferrous sulfate, and the concentration of sodium persulfate in the liquid in the mixed reaction tank 6 is controlled to be 450-550 mg / L, and the concentration of ferrous sulfate is controlled to be 45-55 mg / L. Preferably, the concentration ratio of the sodium persulfate to the sodium sulfate is 10:1, for example, the concentration of the sodium persulfate is controlled to be 500 mg / L, and the concentration of the ferrous sulfate is controlled to be 50 mg / L.

[0036] In one embodiment of the present invention, the number of the groundwater recharge wells 8 is set to be multiple, and the distance between adjacent groundwater recharge wells 8 is 5-10m.

[0037] It should be noted that multiple groundwater recharge wells can all be supplied with relatively clean groundwater after treatment by the same regulating pond, and the regulating pond can adjust the pH, oxygen content, water temperature, etc. to match the characteristics of the groundwater.

[0038] In one embodiment of the present invention, an external discharge pump is further included, and the water in the regulating tank 7 is pumped out by the external discharge pump and sent to the groundwater recharge well 8.

[0039] It should be noted that after installing an external discharge pump, the speed of groundwater recharge can be adjusted. If necessary, a booster pump can also be installed to adjust the pressure of the recharged groundwater.

[0040] In one embodiment of the present invention, the distance between the groundwater extraction well 2 and the groundwater recharge well 8 is more than 200 m.

[0041] The present invention also provides a composite groundwater remediation method for treating petroleum hydrocarbon pollution, which uses the above-mentioned remediation system to perform groundwater remediation treatment, including the following contents:

[0042] S1. Groundwater contaminated by petroleum hydrocarbons first penetrates into the groundwater extraction well 2 through the permeable reaction wall, and part of the pollutants are removed by degradation, adsorption or precipitation of the permeable reaction wall filling medium;

[0043] S2. Start the pressurized water pump 3 to pump the water in the groundwater extraction well 2 into the gas-liquid separator 4 after pressurization. In the gas-liquid separator 4, dense bubbles are formed during the process of releasing the pressure of the groundwater. The volatile organic matter floats up with the bubbles and is discharged to the outside of the gas-liquid separator 4 and is harmlessly treated by the volatile organic matter removal device;

[0044] S3. The liquid in the gas-liquid separator 4 is discharged into the mixed reaction tank 6, and sodium persulfate and ferrous sulfate are added to the mixed reaction tank 6 from the refueling tank. The concentration of sodium persulfate in the liquid in the mixed reaction tank 6 is controlled to be 450-550 mg / L, and the concentration of ferrous sulfate is controlled to be 45-55 mg / L. The concentration ratio of the sodium persulfate to the sodium sulfate is 10:1. After the addition is completed, the reaction is stirred sufficiently;

[0045] S4. After the liquid in the mixed reaction tank 6 is fully reacted, it is discharged into the regulating tank 7. The regulating tank 7 adjusts the pH and oxygen content of the liquid. The pH adjustment can be achieved by using conventional environmentally friendly pH regulators, and the oxygen content is achieved by aeration and other methods. Then, it is discharged to the groundwater recharge well 8. The above process continues until it is found that the groundwater pumped by the pressure pump 3 meets the standard. The detection can be carried out in the form of online monitoring to monitor one or more specific representative pollutants.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite groundwater remediation system for treating petroleum hydrocarbon pollution, characterized in that: The invention comprises a groundwater extraction well (2) and a groundwater recharging well (8) arranged in an area where groundwater is contaminated by petroleum hydrocarbons. The groundwater extraction well (2) is surrounded by a permeable reaction wall. A pressure pump (3), a gas-liquid separator (4), a mixing reaction pool (6) and a regulating pool (7) which are sequentially connected through pipelines are arranged on the ground of the area where groundwater is contaminated by petroleum hydrocarbons. A dosing pool (5) for adding a treatment agent to the mixing reaction pool (6) is arranged near the mixing reaction pool (6). The pressure pump (3) extracts water from the groundwater extraction well (2) and pumps it to the gas-liquid separator (4). The water treated by the gas-liquid separator (4) is sequentially treated in the mixing reaction pool (6) and the regulating pool (7) and then re-injected to the groundwater recharging well (8).

2. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to claim 1, characterized in that: The filling medium of the permeable reaction wall is composed of the following raw materials in the following mass percentages: 10-12% activated carbon, 20-25% calcium peroxide, 8-12% iron powder, 25-35% sodium silicate and 28-32% adhesive.

3. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to claim 1, characterized in that: It also comprises a volatile organic matter removal device, the air inlet of the volatile organic matter removal device being in communication with the gas outlet of the gas-liquid separator (4).

4. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to claim 3, characterized in that: The volatile organic compound removal device includes an adsorption mechanism, a desorption mechanism and a concentrated gas processing mechanism. The adsorption mechanism includes a plurality of adsorption towers connected in series or in parallel. Adsorbents are distributed in the adsorption towers. The desorption mechanism includes a hot air blower. The concentrated gas processing mechanism includes a burner and / or a condenser.

5. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to claim 1, characterized in that: The treatment agents added by the dosing tank (5) to the mixed reaction tank (6) are sodium persulfate and ferrous sulfate. The concentration of sodium persulfate in the liquid in the mixed reaction tank (6) is controlled to be 450-550 mg / L, and the concentration of ferrous sulfate is controlled to be 45-55 mg / L.

6. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to claim 5, characterized in that: The concentration ratio of the sodium persulfate to the sodium sulfate is 10:

1.

7. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to claim 1, characterized in that: The number of the groundwater recharge wells (8) is set to be multiple, and the distance between adjacent groundwater recharge wells (8) is 5-10m.

8. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to claim 1, characterized in that: It also comprises an external discharge pump, through which the water in the regulating pool (7) is pumped out and sent into the groundwater recharging well (8).

9. A composite groundwater remediation system for treating petroleum hydrocarbon pollution according to any one of claims 1 to 8, characterized in that: The distance between the groundwater extraction well (2) and the groundwater recharging well (8) is more than 200 m.

10. A composite groundwater remediation method for treating petroleum hydrocarbon pollution, characterized in that: Using the repair system according to any one of claims 1 to 9 to carry out groundwater repair treatment includes the following contents: S1. Groundwater contaminated by petroleum hydrocarbons first penetrates into the groundwater extraction well (2) through the permeable reaction wall, and part of the pollutants are removed by degradation, adsorption or precipitation of the permeable reaction wall filling medium; S2. Start the pressurized water pump (3) to pump the water in the groundwater extraction well (2) into the gas-liquid separator (4) after pressurization. In the gas-liquid separator (4), the groundwater releases pressure to form dense bubbles, and the volatile organic matter floats up with the bubbles and is discharged to the outside of the gas-liquid separator (4) and is harmlessly treated by the volatile organic matter removal device; S3. The liquid in the gas-liquid separator (4) is discharged into the mixed reaction tank (6), and sodium persulfate and ferrous sulfate are added to the mixed reaction tank (6) from the refueling tank. The concentration of sodium persulfate in the liquid in the mixed reaction tank (6) is controlled to be 450-550 mg / L, and the concentration of ferrous sulfate is controlled to be 45-55 mg / L. The concentration ratio of the sodium persulfate to the sodium sulfate is 10:

1. After the addition is completed, the reaction is stirred thoroughly; S4. After the liquid in the mixing reaction tank (6) is fully reacted, it is discharged into the regulating tank (7), and the regulating tank (7) adjusts the pH and oxygen content of the liquid, and then it is discharged to the groundwater recharge well (8). The above process continues until it is detected that the groundwater pumped by the pressurized water pump (3) meets the standards.

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