Method for controlling and repairing diffusion of organic pollutants in coastal aquifer to seawater

Abstract

The application provides a method for controlling and repairing diffusion of organic pollutants in a coastal aquifer to seawater, which comprises the following steps: 1) determining the conductivity of the coastal groundwater in the contaminated area and the conductivity of the seawater in the sea area; 2) dividing the coastal groundwater area and the seawater area connected therewith into a land-side area, a sea-side area and a salt ion overlapping area; 3) expanding the salt ion overlapping area to the inland side based on the classification of the adsorption coefficient of the organic pollutants and the classification of the biodegradability of the organic pollutants and determining the area as an organic pollutant overlapping area, the area extending to the inland side of the organic pollutant overlapping area being a land-side contaminated area, and the area extending to the sea area of the organic pollutant overlapping area being a sea-side contaminated area; 4) tracing the pollution data of the land-side contaminated area; setting an organic pollutant adsorption device in the organic pollutant overlapping area to perform adsorption repair; and determining whether to perform intensified repair and / or continuous monitoring according to the pollution data of the sea-side contaminated area.

Description

Technical Field

[0001] This invention relates to the field of organic pollutant treatment, and particularly to a method for controlling and remediating the diffusion of organic pollutants from coastal aquifers into seawater. Background Technology

[0002] There are numerous petrochemical enterprises along the coast, and due to the high content and toxicity of their organic matter, there is a significant risk of groundwater organic pollution. Some coastal petrochemical enterprises are located only tens of meters from the coastline, making them highly susceptible to tidal influences that could lead to uncontrollable pollution once groundwater pollution occurs. Furthermore, most pollution remediation efforts involve locating the source before remediation, which delays remediation and makes tracing the source of pollution in complex coastal groundwater flow patterns relatively difficult.

[0003] In addition, there are many common groundwater pollution remediation technologies, including adsorption, extraction, PRB, chemical oxidation, etc., but there is no clear explanation for the remediation of organic pollution in coastal aquifers. Remediation methods based on adsorption mainly utilize multi-layer adsorption or develop highly efficient modified adsorption materials to improve the adsorption effect. For example, Chinese patent CN216513145U proposes an adsorption device for groundwater remediation, which uses a three-layer adsorption plate to increase the contact time of pollutants and improve the adsorption efficiency. There are many articles and patents on the modification of adsorption materials, commonly including activated carbon, zeolite, sponge, etc.

[0004] In summary, coastal oil and petrochemical enterprises pose a significant risk of organic pollution. The migration patterns of organic matter in aquifers are complex due to tidal dynamics, unlike the unidirectional migration patterns in inland areas, making control more difficult. Summary of the Invention

[0005] One aspect of the present invention provides a method for controlling and remediating the diffusion of organic pollutants from coastal aquifers into seawater, comprising the following steps:

[0006] 1) Determine the electrical conductivity of the coastal groundwater within the polluted area and the electrical conductivity of the seawater within the area;

[0007] 2) Based on the conductivity of the coastal groundwater and the conductivity of the seawater, the coastal groundwater area and the seawater connected to it are divided into a land-side area with conductivity equal to that of the coastal groundwater, a sea-side area with conductivity equal to that of the seawater, and a salt ion overlap area located between the land-side area and the sea-side area with conductivity greater than that of the coastal groundwater and less than that of the seawater.

[0008] 3) Determine the types of organic pollutants in the polluted area, then determine the adsorption coefficients of the organic compounds of the organic pollutants, and classify the adsorption coefficients of the organic compounds; determine the biodegradability of the organic pollutants, and classify the biodegradability of the organic pollutants;

[0009] Based on the classification of adsorption coefficients of organic compounds and the classification of biodegradability of organic pollutants, the distance range of the salt ion overlap zone is expanded to the inland side and determined as the organic pollutant overlap zone. The area outside the organic pollutant overlap zone and extending inland is determined as the land-side pollution zone, and the area outside the organic pollutant overlap zone and extending to the sea is determined as the sea-side pollution zone.

[0010] 4) For the land-side contaminated area, the pollution source is identified by tracing the pollution data of the land-side contaminated area;

[0011] For the overlapping area of ​​organic pollutants, an organic pollutant adsorption device is installed in the overlapping area to perform adsorption and remediation until the requirements are met.

[0012] For the polluted area on the seaward side, based on the pollution data of the polluted area on the seaward side, it is determined whether to carry out enhanced remediation and / or continuous monitoring.

[0013] In one specific embodiment, in step 3), the adsorption coefficient of the organic compound is divided into three levels: Level I: greater than 0 and less than or equal to 10, Level II: greater than 10 and less than or equal to 100, and Level III: greater than 100.

[0014] The biodegradability of the organic pollutants is divided into four levels: Level A: greater than 0 and less than or equal to 0.1; Level B: greater than 0.1 and less than or equal to 0.15; Level C: greater than 0.15 and less than or equal to 0.5; Level D: greater than 0.5.

[0015] in,

[0016] When the adsorption coefficient of the organic compound is classified as Level I and the biodegradability of the organic pollutant is classified as any one of the four levels, the salt ion overlap region is expanded by 2 meters.

[0017] When the adsorption coefficient of the organic compound is classified as Grade II and the biodegradability of the organic pollutant is classified as Grade C or D, the salt ion overlap region is expanded by 2 meters.

[0018] When the adsorption coefficient of the organic compound is classified as Grade II and the biodegradability of the organic pollutant is classified as Grade A or Grade B, the salt ion overlap region is expanded by 5 meters.

[0019] When the adsorption coefficient of the organic compound is classified as Grade III and the biodegradability of the organic pollutant is classified as Grade C or D, the salt ion overlap region is expanded by 5 meters.

[0020] When the adsorption coefficient of the organic compound is classified as Grade III and the biodegradability of the organic pollutant is classified as Grade A or Grade B, the salt ion overlap region is expanded by 8 meters.

[0021] In one specific implementation, in step 4), for the land-side contaminated area, the pollution data of the land-side contaminated area is modeled and inverted using GMS software to identify the pollution source, thereby finding the pollution source.

[0022] In one specific implementation, in step 4), for the overlapping area of ​​organic pollutants, formula a) is used to calculate the diffusion distance D of organic pollutants under tidal dynamics within a spring tide cycle.

[0023] D=12960KIa)

[0024] Where K is the flow velocity of water in the aquifer (i.e., groundwater flow velocity), in cm / s, which can be determined based on the "Guide to Hydrogeological Models"; I is the topographic relief.

[0025] Let W be the width of the overlapping area of ​​organic pollutants. Calculate the value N of W / D / 2. When N is less than or equal to 1, a single row of wells is set in the overlapping area of ​​organic pollutants. When N is greater than 1 and N is an integer, N rows of wells are set in the overlapping area of ​​organic pollutants. When N is greater than 1 and N is a decimal, N+1 rows of wells are set in the overlapping area of ​​organic pollutants.

[0026] Organic pollutant adsorption materials are arranged inside the well to form an organic pollutant adsorption device.

[0027] In one specific embodiment, I = h / W, where h is the head difference of the overlapping zone of organic pollutants, and W is the width of the overlapping zone of organic pollutants.

[0028] In one specific embodiment, the organic pollutant adsorbent material is carbon fiber and zeolite.

[0029] In one specific embodiment, the volume ratio of the carbon fiber to the zeolite is 3:1 to 4:1.

[0030] In one specific implementation, in step 4), if the pollution data of the polluted area on the seaward side is lower than the HJ14848 standard, then the polluted area on the seaward side is subject to long-term monitoring.

[0031] In one specific implementation, in step 4), if the pollution data of the polluted area on the seaward side is higher than the HJ14848 standard, then the polluted area on the seaward side is subjected to enhanced remediation.

[0032] In one specific embodiment, during the enhanced remediation, water from the contaminated area on the seaward side is pumped out before high tide, and a bio-agent for degrading organic pollutants and / or an electron acceptor slow-release agent that stimulates the growth of microorganisms in the groundwater of the contaminated area on the seaward side are injected in situ before low tide, thereby improving the degradation efficiency of organic pollutants. The electron acceptor can be oxygen, nitrate, sulfate, etc.

[0033] In one specific implementation, a groundwater extraction pump is used to extract water from the polluted area on the seaward side, wherein extraction begins 3 hours before high tide and continues until the tide reaches its highest point.

[0034] In one specific embodiment, the biological agent and / or the sustained-release preparation are injected in situ using a jet drill, wherein the injection begins 3 hours before the lowest tide and continues until the tide reaches the lowest point of the low tide.

[0035] The beneficial effects of this invention are:

[0036] Some coastal oil and petrochemical enterprises are located tens of meters from the sea, posing a significant risk of organic pollution in their groundwater. Furthermore, the periodic changes in the groundwater flow field due to tidal influences lead to recurring and complex migration patterns of organic pollution, making control extremely difficult and imposing a substantial economic burden on these enterprises due to the high cost of remediation. This invention actively utilizes tidal dynamics to partition the complex organic pollutant migration process into zones, and then uses these zones for pollution source tracing, adsorption remediation, and enhanced remediation. By fully leveraging natural forces, the remediation achieves twice the result with half the effort. Moreover, it involves no large-scale engineering projects, is low-cost, highly safe, and has minimal social impact, effectively improving the prevention and control of organic pollution in groundwater for coastal enterprises.

[0037] This invention is the first to closely integrate the hydrodynamic forces generated by the interaction of tides and regional flow fields with the remediation technology for organic pollutants. Utilizing the reciprocating movement of groundwater in coastal aquifers effectively increases the contact area and time of organic pollutants with adsorbent materials, achieving twice the result with half the effort, significantly reducing energy costs, and improving adsorption efficiency. Furthermore, common extraction techniques and material / bacterial agent injection techniques require flow with the groundwater after injection; combining this with the inherent dynamics of tides can effectively reduce energy consumption and expand the radius of action.

[0038] This invention discovers that the reciprocating motion of overlapping pollution zones provides favorable conditions for adsorption, effectively increasing the contact time of pollutants and improving adsorption efficiency. Therefore, based on the characteristics of pollutant migration and leveraging tidal dynamics, this patent addresses the organic pollution of groundwater in coastal enterprises by dividing the coastal aquifer into zones. By identifying salinity transition zones (i.e., salt ion overlap zones), the location of organic pollutant overlap zones is determined. Adsorption is then carried out in these overlap zones by constructing wells and placing adsorbent materials. This fully utilizes the periodically changing flow field without requiring additional power, allowing pollutants to be continuously adsorbed and treated during the reciprocating motion. The adsorbent materials selected are activated carbon fiber with sufficient support and zeolite with a density greater than water that is less prone to desorption, ensuring the overall condition of the adsorbent material within the well. For the polluted areas on the seaside outside the organic pollutant overlap zones, if the pollution exceeds the standard, staged extraction and material injection using tidal dynamics are employed to increase the technical coverage area and achieve twice the result with half the effort. The polluted areas on the landside are directly generalized as a unidirectional pollution migration process. This complex migration process is segmented, and measures are taken for each segment, providing an effective groundwater management technology for organic pollution in coastal aquifers.

[0039] This invention addresses potential organic pollution in groundwater at coastal oil and petrochemical enterprises. Leveraging the dynamics of tidal-induced groundwater flow field changes, it analyzes and treats the complex migration process of organic pollutants step-by-step. For overlapping areas of organic pollutants—regions of repeated migration—the invention pinpoints their locations and employs adsorption technology for remediation. This requires no additional power, as the reciprocating movement of pollutants enhances adsorption efficiency. For polluted areas exceeding standards on the seaward side, remediation is intensified by extraction or injection based on tidal dynamics, significantly increasing the treatment coverage area. Polluted areas on the landward side are simply represented as one-dimensional unidirectional migration, and source tracing is achieved through software simulation and prediction. This segmented remediation approach across the entire chain achieves optimal results with minimal effort. This patent effectively enhances the groundwater risk management capabilities of coastal enterprises.

[0040] Because research on the remediation of organic pollutants in groundwater mainly focuses on the development and application of single technologies, relying primarily on artificial power, it makes little use of changes in groundwater flow fields and ignores the role of natural forces such as tides, often resulting in inefficient efforts. Furthermore, there is currently no mature technical system for the remediation of coastal aquifers with complex organic pollutant migration patterns. Therefore, this invention combines the characteristics of groundwater flow field changes in coastal aquifers, divides the aquifer into zones according to the migration process of organic pollutants, and carries out remediation / source tracing / monitoring in blocks. It breaks down complex problems and utilizes low-cost technology with the help of tidal power to effectively achieve pollution control. Attached Figure Description

[0041] Figure 1 A schematic diagram showing the migration process of organic pollutants in coastal groundwater is displayed.

[0042] Figure 2 A flowchart of the method of the present invention is shown.

[0043] Figure 3 The diagram shows how to divide the coastal aquifer into three zones for remediation: a land-side polluted zone, a sea-side polluted zone, and an overlapping zone of organic pollutants. Detailed Implementation

[0044] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0045] Based on the "Technical Guidelines for Risk Assessment of Contaminated Sites" (HJ 25.3-2014), the adsorption coefficient of organic compounds (KOC) was determined, and KOC was divided into three levels: Level I: greater than 0 and less than or equal to 10 cm⁻¹. 3 / g, Grade II: greater than 10 cm 3 / g and less than or equal to 100 cm 3 / g, Grade III: greater than 100 cm 3 / g.

[0046] The biodegradability of organic pollutants can be expressed by the BOD5 / COD ratio, which is obtained by sampling and measuring in the polluted area. It is divided into four levels: Level A: greater than 0 and less than or equal to 0.1, Level B: greater than 0.1 and less than or equal to 0.15, Level C: greater than 0.15 and less than or equal to 0.5, and Level D: greater than 0.5.

[0047] Based on the KOC classification and the biodegradability classification of organic pollutants, the distance extending inland is determined to expand the scope of the salt ion overlap zone, thereby defining the scope of the organic pollutant overlap zone. The specific inland extension distances are shown in Table 1 below.

[0048] Table 1

[0049]

[0050] Example 1

[0051] An organic pollution incident occurred in the groundwater of a 52m deep petrochemical plant located near the sea, which urgently needs to be controlled.

[0052] 1) The conductivity of groundwater in this area is determined to be 0.12 S / m, and the conductivity of seawater is 4 S / m.

[0053] 2) Based on the above conductivity values, the coastal aquifer is first divided into three regions: the landward region, the salt ion overlap region, and the seaward region. The region with a conductivity of 0.12 S / m is the landward region; the region with a conductivity between 0.12 S / m and 4 S / m is the salt ion overlap region; and the region with a conductivity of 4 S / m is the seaward region. Final result: Taking the coastline as the reference, the area extending inland within 10 m is the seaward region; the area extending inland from 10 m to 30 m is the salt ion overlap region; and the area extending inland 30 m to the factory area is the landward region.

[0054] 3) Groundwater sampling near the petrochemical plant revealed groundwater contamination, with toluene as the main organic pollutant. According to the "Technical Guidelines for Risk Assessment of Contaminated Sites" (HJ 25.3-2014), the KOC of toluene is 234 cm⁻¹. 3 / g, level III; the BOD5 / COD ratio was measured to be 0.102, and the biodegradability level of organic matter was level B. According to Table 1, still using the coastline as the baseline, the range of the salt ion overlap zone was expanded by 8 m inland, thus determining the range of the organic pollutant overlap zone as follows: from the coastline to 38 m inland; the area within 10 m inland is the seaside pollution zone, and the area extending 38 m inland to the factory area is the landside pollution zone.

[0055] 4) For the land-side pollution area, based on the pollution data, the process in the land-side pollution area is generalized into a unidirectional process. The pollution source is modeled and predicted using GMS software based on the data of the land-side pollution area. The results indicate that a certain aromatic hydrocarbon unit is a suspected pollution source.

[0056] For areas of overlapping organic pollutants, firstly, use formula a) to calculate the distance D of simple hydrodynamic diffusion of organic pollutants within one tidal cycle (15 days).

[0057] D=12960KIa)

[0058] The above formula is derived from D=15×3600×24 / 100KI, where 15 is the number of days in the spring tide cycle, 3600 is the conversion between hours and seconds, 24 is the conversion between days and hours, 100 is the conversion between meters and centimeters, K is the flow velocity of groundwater in the aquifer, determined based on the "Guide to Hydrogeological Models", in cm / s, and in this embodiment K=3cm / s; I is the hydrogeological parameter, i.e., topographic relief, where I=h / W, h is the head difference of the overlapping zone of organic pollutants, in meters, in this embodiment 0.056 meters, W is the width of the overlapping zone of organic pollutants, in meters, in this embodiment 28 meters, and I=2‰ in this embodiment;

[0059] Calculations show that D = 77.76 m. Since D = 77.76 m is much larger than the width W = 28 meters of the overlapping organic pollutant zone determined above, a single row of wells can be directly installed in the overlapping zone to meet the remediation requirements. After the wells are installed, adsorption devices composed of carbon fiber and zeolite are placed inside. The adsorption device adopts a cylindrical filling assembly type, with 80% of the carbon fiber volume as the skeleton, prepared into a cylindrical shape. After the carbon fiber is prepared into a cylindrical skeleton, 20% of the volume of zeolite is added into it, so that the zeolite is interspersed in the carbon fiber skeleton. Based on the adsorption capacity of the adsorption device and the degree of pollution in the overlapping organic pollutant zone, the adsorption device is replaced when it is saturated or close to saturation.

[0060] For the polluted area on the seaside, before the remediation of the overlapping area of ​​organic pollutants, the concentration of organic pollutants within 3 meters of the overlapping area of ​​organic pollutants was tested. The test results showed that the concentration of organic pollutants met the Class IV water requirements in the HJ14848 standard. Therefore, only long-term monitoring is required, that is, testing once every quarter.

[0061] 5) After six months of adsorption in the overlapping area of ​​organic pollutants, the remediation was suspended to verify its effectiveness, specifically by testing the concentration of organic pollutants in the polluted area on the seaward side. This involved measuring the concentration of organic pollutants within 3 meters of the overlapping area on the seaward side after another high tide. The result showed that the concentration was 20% of the pre-remediation level and met the Class IV water requirements of the HJ14848 standard. Therefore, the remediation was effective and could be discontinued.

[0062] Example 2

[0063] An organic pollution incident occurred in the groundwater of a petrochemical plant located 130 meters from the sea, which urgently needs to be controlled.

[0064] 1) The conductivity of groundwater in this area was determined to be 700 μS / cm, and the conductivity of seawater was 4.5 S / m.

[0065] 2) Based on the above conductivity values, the coastal aquifer is first divided into three regions: the landward region, the salt ion overlap region, and the seaward region. The region with a conductivity of 700 μS / cm is the landward region; the region with a conductivity between 700 μS / cm and 4.5 S / m is the salt ion overlap region; and the region with a conductivity of 4.5 S / m is the seaward region. Final result: Taking the coastline as the reference point, the area extending inland within 30m is the seaward region; the area extending inland from 30m to 90m is the salt ion overlap region; and the area extending inland 90m to the factory area is the landward region.

[0066] 3) Groundwater sampling near the petrochemical plant revealed groundwater contamination, with aniline as the main organic pollutant. According to the "Technical Guidelines for Risk Assessment of Contaminated Sites" (HJ 25.3-2014), the KOC concentration of aniline is 70.2 cm³. 3 / g, classified as Level II; BOD5 / COD was measured to be 0.73, classifying the organic matter biodegradability as Level D. According to Table 1, still using the coastline as the baseline, the area of ​​the salt ion overlap zone is expanded by 2 m inland. Therefore, the extent of the organic pollutant overlap zone is determined as follows: from the coastline, extending inland from 30 m to 92 m; the area within 30 m inland is the seaside pollution zone, and the area extending inland to the factory area is the landside pollution zone.

[0067] 4) For the land-side pollution zone, based on the pollution data, the process in the land-side pollution zone is generalized into a unidirectional process. The pollution source is modeled and predicted using GMS software based on the data of the land-side pollution zone. The results indicate that a certain ethylene unit is a suspected pollution source.

[0068] For areas of overlapping organic pollutants, firstly, use formula a) to calculate the distance D of simple hydrodynamic diffusion of organic pollutants within one tidal cycle (15 days).

[0069] D=12960KIa)

[0070] Wherein, K is the flow velocity of groundwater in the aquifer, determined based on the "Guide to Hydrogeological Models", in cm / s, and in this embodiment K=0.3cm / s; I is a hydrogeological parameter, i.e. topographic relief, where I=h / W, h is the head difference of the overlapping zone of organic pollutants, in meters, and in this embodiment h=0.065 meters; W is the width of the overlapping zone of organic pollutants, in meters, and in this embodiment W=62 meters; and in this embodiment I=1‰.

[0071] Calculations show D = 3.89m. Therefore, the area that can be covered by tidal dynamics for organic pollutant remediation is relatively small: (92m - 30m) / 3.89 / 2 = 7.97. Thus, at least 8 rows of adsorption wells are needed to meet the remediation requirements. After the wells are laid out, adsorption devices composed of carbon fiber and zeolite are placed inside. These devices are cylindrical and assembled, with 75% carbon fiber as the skeleton, and 25% zeolite is added to the carbon fiber skeleton, allowing the zeolite to be interspersed within it. Based on the adsorption capacity of the devices and the pollution level in overlapping organic pollutant areas, the devices are periodically replaced when saturated or near saturation.

[0072] For the polluted area on the seaward side, before the remediation of the overlapping area of ​​organic pollutants, the concentration of organic pollutants within 3 meters of the overlapping area was tested. The results showed that the concentration of organic pollutants did not meet the Class IV water requirements in the HJ14848 standard. Therefore, the remediation needs to be strengthened. The pumping technique was adopted, and water was pumped out 3 hours before high tide until the tide reached its highest point to carry out the enhanced remediation.

[0073] 5) After five months of adsorption in the overlapping area of ​​organic pollutants and the same amount of extraction in the polluted area on the seaward side, the remediation was suspended to verify its effectiveness, specifically by testing the concentration of organic pollutants in the polluted area on the seaward side. This involved measuring the concentration of organic pollutants within 3 meters of the overlapping area on the seaward side after another high tide. The result showed that the concentration was 5% of the pre-remediation concentration and met the Class IV water requirements of the HJ14848 standard. Therefore, the remediation was effective and could be discontinued.

[0074] Example 3

[0075] An organic pollution incident occurred in the groundwater of a petrochemical plant located 100 meters from the sea, which urgently needs to be controlled.

[0076] 1) The conductivity of groundwater in this area was determined to be 650 μS / cm, and the conductivity of seawater was 4 S / m.

[0077] 2) First, based on the above conductivity values, the coastal aquifer is divided into three regions: the landward region, the salt ion overlap region, and the seaward region. The region with a conductivity of 650 μS / cm is the landward region, the region with a conductivity between 650 μS / cm and 4 S / m is the salt ion overlap region, and the region with a conductivity of 4 S / m is the seaward region. The final result is: with the coastline as the reference, the area extending inland within 20m is the seaward region, the area extending inland from 20m to 50m is the salt ion overlap region, and the area extending inland to the factory area 50m is the landward region.

[0078] 3) Groundwater sampling near the petrochemical plant revealed groundwater contamination, with benzene as the main organic pollutant. According to the "Technical Guidelines for Risk Assessment of Contaminated Sites" (HJ 25.3-2014), the KOC of benzene is 146 cm⁻¹. 3 / g, classified as Level III; BOD5 / COD was measured to be 0.163, and the biodegradability of organic matter was classified as Level C. According to Table 1, still using the coastline as the baseline, the overlap zone of salt ions was expanded by 5 m inland. Therefore, the extent of the overlap zone for organic pollutants was determined as follows: based on the coastline, extending inland from 20 m to 55 m; the area within 20 m inland is the seaside pollution zone, and the area extending inland to the factory area is the landside pollution zone.

[0079] 4) For the land-side pollution area, based on the pollution data, the process in the land-side pollution area is generalized into a unidirectional process. Using the data from the land-side pollution area, GMS software is used to model and predict the pollution source. The results indicate that a certain aromatics tank is a suspected pollution source.

[0080] For areas of overlapping organic pollutants, firstly, use formula a) to calculate the distance D of simple hydrodynamic diffusion of organic pollutants within one tidal cycle (15 days).

[0081] D=12960KIa)

[0082] Wherein, K is the flow velocity of groundwater in the aquifer, determined based on the "Guide to Hydrogeological Models", in cm / s, and in this embodiment K=0.03cm / s; I is a hydrogeological parameter, i.e. topographic relief, where I=h / W, h is the head difference of the overlapping zone of organic pollutants, in meters, and in this embodiment h=0.072 meters; W is the width of the overlapping zone of organic pollutants, in meters, and in this embodiment W=35 meters; and in this embodiment I=2‰.

[0083] Calculations show D = 0.78m. Therefore, the area that can be covered by tidal dynamics for organic pollutant remediation is relatively small: (55m - 20m) / 0.78 / 2 = 22.44. Thus, at least 23 rows of adsorption wells are needed to meet the remediation requirements. After the wells are laid out, adsorption devices composed of carbon fiber and zeolite are placed inside. The adsorption device uses a cylindrical filling assembly, with 77% carbon fiber as the skeleton, and 23% zeolite is added to the cylindrical skeleton, allowing the zeolite to be interspersed within the carbon fiber skeleton. Based on the adsorption capacity of the adsorption device and the pollution level in the overlapping areas of organic pollutants, the adsorption device is periodically replaced when it is saturated or near saturation.

[0084] For the polluted area on the seaward side, before the remediation of the overlapping area of ​​organic pollutants, the concentration of organic pollutants within 3 meters of the overlapping area was tested. The results showed that the concentration of organic pollutants did not meet the Class IV water requirements in the HJ14848 standard. Therefore, the remediation needs to be strengthened. The technical means of injecting biological agents for the remediation of organic pollutants was adopted. The injection began 3 hours before the lowest tide and continued until the tide reached the lowest point of the low tide.

[0085] 5) After three months of adsorption in the overlapping area of ​​organic pollutants and the same amount of bioremediation in the polluted area on the seaward side, the remediation was suspended to verify its effectiveness, specifically by testing the concentration of organic pollutants in the polluted area on the seaward side. After another spring tide, the concentration of organic pollutants within 3 meters of the overlapping area on the seaward side was measured. The result was 52% of the pre-remediation concentration, failing to meet the Class IV water requirements of the HJ14848 standard, thus not meeting the remediation requirements. The adsorption device needed to be replaced, and biological agents for organic pollutant remediation needed to be added. After another two months, the remediation was suspended again to verify its effectiveness, again after another spring tide. The concentration of organic pollutants within 3 meters of the overlapping area on the seaward side was measured. The result was 12% of the pre-remediation concentration, meeting the Class IV water requirements of the HJ14848 standard, indicating that the remediation was effective and the remediation was terminated.

[0086] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A method for controlling and remediating the diffusion of organic pollutants from coastal aquifers into seawater, comprising the following steps: 1) Determine the electrical conductivity of the coastal groundwater and the seawater in the polluted area; 2) Based on the conductivity of the coastal groundwater and the conductivity of the seawater, the coastal groundwater area and the seawater connected to it are divided into a land-side area with conductivity equal to that of the coastal groundwater, a sea-side area with conductivity equal to that of the seawater, and a salt ion overlap area located between the land-side area and the sea-side area with conductivity greater than that of the coastal groundwater and less than that of the seawater. 3) Determine the types of organic pollutants in the polluted area, then determine the adsorption coefficients of the organic compounds of the organic pollutants, and classify the adsorption coefficients of the organic compounds; determine the biodegradability of the organic pollutants, and classify the biodegradability of the organic pollutants; Based on the classification of adsorption coefficients of organic compounds and the classification of biodegradability of organic pollutants, the distance range of the salt ion overlap zone is expanded to the inland side and determined as the organic pollutant overlap zone. The area outside the organic pollutant overlap zone and extending inland is determined as the land-side pollution zone, and the area outside the organic pollutant overlap zone and extending to the sea is determined as the sea-side pollution zone. 4) For the land-side contaminated area, the pollution source is identified by tracing the pollution data of the land-side contaminated area; for the organic pollutant overlapping area, an organic pollutant adsorption device is installed in the organic pollutant overlapping area to carry out adsorption and remediation until the requirements are met. For the polluted area on the seaward side, determine whether to carry out enhanced remediation and / or continuous monitoring based on the pollution data of the polluted area on the seaward side; In step 3), the adsorption coefficient of the organic compound is divided into three levels: Level I: greater than 0 and less than or equal to 10, Level II: greater than 10 and less than or equal to 100, and Level III: greater than 100. The biodegradability of the organic pollutants is divided into four levels: Level A: greater than 0 and less than or equal to 0.1; Level B: greater than 0.1 and less than or equal to 0.15; Level C: greater than 0.15 and less than or equal to 0.5; Level D: greater than 0.

5. in, When the adsorption coefficient of the organic compound is classified as Level I and the biodegradability of the organic pollutant is classified as any one of the four levels, the salt ion overlap region is expanded by 2 meters. When the adsorption coefficient of the organic compound is classified as Grade II and the biodegradability of the organic pollutant is classified as Grade C or D, the salt ion overlap region is expanded by 2 meters. When the adsorption coefficient of the organic compound is classified as Grade II and the biodegradability of the organic pollutant is classified as Grade A or Grade B, the salt ion overlap region is expanded by 5 meters. When the adsorption coefficient of the organic compound is classified as Grade III and the biodegradability of the organic pollutant is classified as Grade C or D, the salt ion overlap region is expanded by 5 meters. When the adsorption coefficient of the organic compound is classified as Grade III and the biodegradability of the organic pollutant is classified as Grade A or Grade B, the salt ion overlap region is expanded by 8 meters.

2. The control and repair method according to claim 1, characterized in that, In step 4), for the land-side contaminated area, the pollution data of the land-side contaminated area is modeled and inverted using GMS software to identify the pollution source.

3. The control and repair method according to claim 1, characterized in that, In step 4), for the overlapping area of ​​organic pollutants, the diffusion distance D of organic pollutants under tidal dynamics within one tidal cycle is calculated using formula a), where D = 12960KI a). Where K is the flow velocity of water in the aquifer, in cm / s; I is the topographic relief. Taking the width of the organic pollutant overlap zone as W, calculate the value N of W / D / 2. When N is less than or equal to 1, a single row of wells is set in the organic pollutant overlap zone. When N is greater than 1 and N is an integer, N rows of wells are set in the organic pollutant overlap zone. When N is greater than 1 and N is a decimal, N+1 rows of wells are set in the organic pollutant overlap zone. Organic pollutant adsorption material is arranged in the wells to form an organic pollutant adsorption device.

4. The control and repair method according to claim 3, characterized in that, I = h / W, where h is the head difference in the overlapping zone of the organic pollutants, and W is the width of the overlapping zone of the organic pollutants.

5. The control and repair method according to claim 3, characterized in that, The organic pollutant adsorbents are carbon fiber and zeolite.

6. The control and repair method according to claim 5, characterized in that, The volume ratio of the carbon fiber to the zeolite is 3:1 to 4:

1.

7. The control and repair method according to claim 1, characterized in that, In step 4), if the pollution data of the polluted area on the seaward side is lower than the HJ14848 standard, then the polluted area on the seaward side will be monitored for a long time.

8. The control and repair method according to claim 1, characterized in that, In step 4), if the pollution data of the polluted area on the seaward side is higher than the HJ14848 standard, then the polluted area on the seaward side will be subject to enhanced remediation.

9. The control and repair method according to claim 8, characterized in that, During the enhanced remediation, water in the polluted area on the seaward side is extracted before high tide, and biological agents that degrade organic pollutants and / or electron acceptor slow-release agents that stimulate the growth of microorganisms in the groundwater of the polluted area on the seaward side are injected in situ before low tide, thereby improving the degradation efficiency of organic pollutants.

10. The control and repair method according to claim 9, characterized in that, The water in the polluted area on the seaward side is extracted using groundwater extraction pumps. Extraction begins 3 hours before high tide and continues until the tide reaches its highest point.

11. The control and repair method according to claim 9, characterized in that, The biological agent and / or the sustained-release preparation are injected in situ using a jet drill, wherein the injection begins 3 hours before the lowest tide and continues until the tide reaches the lowest point of the low tide.

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