Remediation system for organochlorine pesticide contaminated soil
By implementing a multi-step, graded remediation approach for soil contaminated with organochlorine pesticides, and utilizing methods such as screening, water leaching, chemical oxidation, and washing, the problem of ineffective single remediation technologies has been solved. This approach achieves efficient and low-cost soil remediation and reduces secondary emissions of pollutants.
Patent Information
- Application Number
- CN202520277827.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-20
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2035-02-20
AI Technical Summary
Existing technologies often fail to effectively remove soil contaminated with organochlorine pesticides, resulting in poor remediation outcomes and high costs.
A graded and batch-based remediation system is adopted, including a screening device, a water leaching device, a chemical oxidation remediation device, and a chemical leaching remediation device. Different remediation methods are used for soils with different particle sizes, and thermal desorption and gas treatment are combined to achieve multi-step remediation.
It improves the removal efficiency of pollutants, reduces remediation costs, and reduces secondary pollution by recycling leaching and washing solutions.
Smart Images
Figure CN223888693U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of soil pollution remediation technology, specifically relating to a soil remediation system for organochlorine pesticide-contaminated soil. Background Technology
[0002] In recent years, with the acceleration of urbanization and the continuous advancement of industrial restructuring in my country, as well as the implementation of national policies such as "relocating secondary industries to tertiary industries" and "moving industries out of urban areas and into industrial parks," enterprises in central urban areas have been relocating one after another, leaving behind a large number of sites contaminated with organochlorine pesticides (DDT, DDT, HCH, chlordane, methylphenidate, etc.). These contaminated sites are mostly located in old urban areas or urban-rural fringe areas, and are facing urgent land use conversion and secondary development, such as conversion into commercial land, residential housing, or public recreational areas. The high concentrations of organochlorine pesticides remaining in the soil of these sites will become "chemical time bombs," seriously threatening human health, environmental safety, and social welfare, and have become a pressing soil environmental problem that needs to be addressed.
[0003] Organochlorine pesticides are a typical class of recalcitrant organic compounds. They are almost impossible to degrade by microorganisms, or require a very long time to degrade. They easily accumulate in the environment and pose various types of hazards to humans and animals, including acute toxicity, chronic toxicity, carcinogenic, teratogenic, and mutagenic effects, as well as endocrine disruption effects. In addition, organochlorine pesticides also have the characteristics of persistent organic pollutants such as bioaccumulation and semi-volatile properties, causing many serious and widespread environmental problems.
[0004] Currently, remediation methods for soil contaminated with organochlorine pesticides mainly include water leaching, chemical oxidation, thermal desorption, chemical washing, and co-treatment in cement kilns. Water leaching typically uses a water leaching device, usually a leaching column, to remediate contaminated soil. The contaminated soil is placed inside the column and leached with clean water. The filtered soil is then tested to see if it meets standards. Chemical oxidation usually requires pre-activating agents and oxidants. These are introduced into a chemical oxidation remediation device to pre-activate and chemically oxidize the contaminated soil. To accelerate the reaction, a heating unit can be used to heat the chemical oxidation remediation device. Commonly used pre-activating agents include ferrous citrate chelate, calcium oxide, and calcium peroxide, while sodium persulfate is a common oxidant. Thermal desorption usually requires co-additives. These are added to the thermal desorption remediation device to synergistically desorb the contaminated soil. Co-additives can include nano-iron and activated carbon. Thermal desorption remediation devices typically use thermal desorbers, such as tubular thermal desorbers. Chemical leaching typically involves using a leaching agent to wash contaminated soil within a chemical leaching remediation device. To accelerate the reaction, a heating unit can be used to heat the device. Commonly used leaching agents are organic-inorganic mixtures. Organic leaching agents include Triton TX-100, sodium dodecyl sulfate, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate, while inorganic leaching agents include sodium hydroxide, sodium carbonate, and sodium bicarbonate. Because soil contaminated with organochlorine pesticides often contains complex organic pollutants, most of which are semi-volatile or persistent and difficult to degrade, single remediation technologies often fail to achieve the desired remediation results. Utility Model Content
[0005] In view of the existing technical problems, this utility model aims to provide a soil remediation system for organochlorine pesticide contaminated soil. This remediation system can solve the technical problem that single remediation technologies in the prior art are difficult to achieve the expected remediation effect.
[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0007] An organochlorine pesticide contaminated soil remediation system is characterized by the following structural features: it includes a screening device, a water leaching device, a chemical oxidation remediation device, and a chemical leaching remediation device. Both the chemical oxidation and chemical leaching remediation devices are equipped with a stirring unit. The screening device has two layers of screens along its height, with the upper screen having a larger aperture than the lower screen. The output end of the upper screen is connected to the soil inlet of the water leaching device, the output end of the lower screen is connected to the soil inlet of the chemical oxidation remediation device, and the output end of the lower screen is connected to the soil inlet of the chemical leaching remediation device.
[0008] This invention's remediation system employs different remediation methods to grade and batch-treat contaminated soils based on their particle size. Because the contaminants in contaminated soils of different particle sizes exist in different states, large and medium-sized particles have small specific surface areas, with most contaminants located on the particle surface. Small-particle contaminated soils, on the other hand, have large specific surface areas, with contaminants located both inside the particle pores and on the particle surface. Conventional leaching methods are insufficient to remove contaminants from the particle pores. Based on the different states of contaminant presence, a water leaching device is used for large-particle contaminated soil, a chemical leaching device is used for medium-particle contaminated soil, and a chemical oxidation device is used for small-particle contaminated soil. This invention's organochlorine pesticide contaminated soil remediation system, through graded and batch-based combined remediation, enables efficient remediation of soils within different particle size ranges. Compared to using a single remediation technology, it achieves better contaminant removal while reducing remediation costs.
[0009] Preferably, the soil outlets of the water leaching device, the chemical oxidation remediation device, and the chemical leaching remediation device are all connected to the soil inlet of the thermal desorption remediation device. The soil treated by the water leaching device, the chemical oxidation remediation device, and the chemical leaching remediation device is tested. If the remediation target is not met, the treated soil is transported to the thermal desorption remediation device for thermal desorption treatment until the remediation target is achieved.
[0010] Preferably, the gases generated in the chemical leaching remediation device and the thermal desorption remediation device are connected to the gas inlet of a gas condensation device via pipelines, and the gas outlet of the gas condensation device is connected to the gas inlet of the activated carbon adsorption device. To avoid environmental pollution from the gases generated during the remediation process, the gases generated in the chemical leaching remediation device and the thermal desorption remediation device are condensed and adsorbed by activated carbon before being discharged into the air.
[0011] Specifically, the soil outlet of the thermal desorption remediation device is connected to the soil inlet of the thermal desorption remediation device. If the soil after remediation by the thermal desorption remediation device does not reach the remediation target value, it is returned to the thermal desorption remediation device to continue remediation until the remediation target value is reached.
[0012] Preferably, the aperture of the upper screen in the screening device is less than 20 mesh, and the aperture of the lower screen in the screening device is not less than 40 mesh.
[0013] Specifically, the screening device is a shaking screen or a vibrating screen.
[0014] Preferably, the leaching outlet of the water leaching device and the leaching outlet of the chemical leaching remediation device are both connected to the dosing port of the chemical oxidation device, which is equipped with a stirring unit. The chemical oxidation device also has an oxidant dosing port and a pre-activating agent dosing port, and its outlet is connected to the feed port of the sedimentation separation device. After collection, the leaching and leaching solutions are tested. If they exceed the Class IV standard of the "Groundwater Quality Standard" (GB / T14848-2017), they are transported to the chemical oxidation device for further treatment. Commonly used pre-activating agents include ferrous citrate chelate, calcium oxide, and calcium peroxide. Commonly used oxidants include sodium persulfate. The COD and organic matter in the wastewater generated by the water leaching and chemical leaching devices are oxidized and decomposed in the chemical oxidation device, thereby removing pollutants and preventing secondary pollution.
[0015] Preferably, the liquid outlet of the sedimentation separation device is connected to the liquid inlet of the water leaching device. After sedimentation and sludge-water separation, the supernatant of the oxidized wastewater can be recycled as the leaching liquid for the water leaching device, and the sludge generated in the sedimentation separation device can be transported to a qualified hazardous waste center for disposal.
[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0017] 1. The organochlorine pesticide contaminated soil remediation system of this utility model, through graded and batch-by-batch combined remediation of contaminated soil, enables soil with different particle size ranges to be efficiently remediated. Compared with the use of single remediation technology, the pollutant removal effect is better, while the remediation cost is reduced.
[0018] 2. The organochlorine pesticide contaminated soil remediation system of this utility model can be recycled after treatment of the leachate or washing solution generated during the remediation process, without secondary pollution. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the structure of the organochlorine pesticide contaminated soil remediation system of this utility model;
[0020] Figure 2 yes Figure 1 A flowchart of the soil remediation process.
[0021] In the figure
[0022] 1-Screening device; 2-Water leaching device; 3-Chemical oxidation repair device; 4-Chemical rinsing repair device; 5-Thermal desorption repair device; 6-Gas condensation device; 7-Activated carbon adsorption device; 8-Chemical oxidation device; 9-Precipitation separation device. Detailed Implementation
[0023] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" appearing below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.
[0024] like Figure 1 As shown, this embodiment provides a soil remediation system for organochlorine pesticide contaminated soil, comprising a screening device 1, a water leaching device 2, a chemical oxidation remediation device 3, a chemical leaching remediation device 4, a thermal desorption remediation device 5, a gas condensation device 6, an activated carbon adsorption device 7, a chemical oxidation device 8, and a precipitation separation device 9. The thermal desorption remediation device 5 is a tubular thermal desorber. The screening device 1 is a disc vibrating screen with two layers of screens along its height. The upper screen has a mesh size of 16, and the lower screen has a mesh size of 40. The output end of the oversize material from the upper screen of the screening device 1 is connected to the soil feeding port of the water leaching device 2. The output end of the undersize material from the lower screen of the screening device 1 is connected to the soil feeding port of the chemical oxidation remediation device 3. The output end of the oversize material from the lower screen of the screening device 1 is connected to the soil feeding port of the chemical leaching remediation device 4. The soil outlets of the water leaching device 2, chemical oxidation remediation device 3, and chemical leaching remediation device 4 are all connected to the soil feed inlet of the thermal desorption remediation device 5. The gas generated in the chemical leaching remediation device 4 and the thermal desorption remediation device 5 is connected to the gas inlet of the gas condensation device 6 via a pipeline. The gas outlet of the gas condensation device 6 is connected to the gas inlet of the activated carbon adsorption device 7. The leaching liquid outlets of the water leaching device 2 and the chemical leaching remediation device 4 are both connected to the dosing port of the chemical oxidation device 8. The chemical oxidation remediation devices 3, 4, and 8 are equipped with stirring units. The chemical oxidation device 8 is also equipped with an oxidant dosing port and a pre-activation agent dosing port. The liquid outlet of the chemical oxidation device 8 is connected to the feed inlet of the precipitation separation device 9, and the liquid outlet of the precipitation separation device 9 is connected to the liquid feed inlet of the water leaching device 2.
[0025] like Figure 1 and Figure 2As shown, the organochlorine pesticide-contaminated soil to be treated is conveyed to a disc vibrating screen for screening. The particle size of the material overlaid on the upper screen is greater than 1000 μm, the particle size of the material overlaid on the lower screen is greater than 500 μm but not greater than 1000 μm, and the particle size of the material underlaid on the lower screen is not greater than 500 μm. Large soil particles with a particle size greater than 1000 μm are conveyed to the water leaching device 2 for leaching with clean water. The leaching liquid is collected and tested. If the test shows that the leaching liquid exceeds the Class IV standard of the "Groundwater Quality Standard" (GB / T14848-2017), the leaching liquid is conveyed to the chemical oxidation device 8 for further treatment. If it does not exceed the standard, it can be recycled. Medium-sized soil particles (greater than 500 μm and less than 1000 μm) are transported to the chemical leaching remediation device 4 for heated leaching. The leaching agent is an organic-inorganic leaching agent. The organic leaching agent consists of Triton TX-100, sodium dodecyl sulfate, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate. The inorganic leaching agent consists of sodium hydroxide, sodium carbonate, and sodium bicarbonate. The heating temperature is 50–95℃, and magnetic stirring is used within the chemical leaching remediation device 4. Fine-sized soil particles (less than 500 μm) are transported to the chemical oxidation remediation device 3 for pre-activation chemical oxidation. The oxidant is sodium persulfate, and the pre-activation agents are ferrous citrate chelate, calcium oxide, and calcium peroxide, added at 1.2–1.5 times the theoretical amount. The pre-activation time is 5–30 minutes. The soil remediated in the water leaching device 2, chemical oxidation remediation device 3, and chemical leaching remediation device 4 is tested. If the remediation target value is not met, the remediated soil is transferred to the thermal desorption remediation device 5 for synergistic thermal desorption. The synergistic additives are nano-iron and activated carbon, and the synergistic thermal desorption temperature is 150-200℃. The soil remediated in the thermal desorption remediation device 5 is tested again. If the remediation target value is still not met, the soil is returned to the thermal desorption remediation device 5 for continued thermal desorption until the remediation target is met, and the remediation work is completed. The substandard leaching liquid discharged from the water leaching device 2 and the leaching liquid discharged from the chemical leaching remediation device 4 are transferred to the chemical oxidation device 8 for pre-activation chemical oxidation treatment. The oxidant used is sodium persulfate, and the pre-activation agents are ferrous citrate chelate, calcium oxide, and calcium peroxide, with an addition amount of 1.2-1.5 times the theoretical amount, and a pre-activation time of 5-30 minutes. Under the action of chemical oxidation, COD, organic matter, etc. in the wastewater are oxidized and decomposed, thereby removing pollutants. After oxidation, the wastewater enters the sedimentation and separation device 9 for sedimentation and mud-water separation. If the supernatant meets the Class IV water quality standard of the "Groundwater Quality Standard" (GB / T14848-2017), it can be returned to the water leaching device 2 for recycling or discharged. The sludge is transported to a qualified hazardous waste center for disposal. To avoid environmental pollution from gases generated during soil remediation, the gases generated in the chemical leaching remediation device 4 and the thermal desorption remediation device 5 are condensed by the gas condensation device 6 and adsorbed by activated carbon in the activated carbon adsorption device 7 before being released into the air.
[0026] The above embodiments should be understood as being used only to illustrate the utility model more clearly, and not to limit the scope of the utility model. After reading this utility model, any modifications of the embodiments by those skilled in the art in various equivalent forms fall within the scope defined by the appended claims.
Claims
1. A soil remediation system for organochlorine pesticide contaminated with soil, characterized in that: It includes a screening device (1), a water leaching device (2), a chemical oxidation repair device (3) and a chemical rinsing repair device (4), and both the chemical oxidation repair device (3) and the chemical rinsing repair device (4) are equipped with a stirring unit; The screening device (1) has two layers of screens along the height direction, with the aperture of the upper screen being larger than that of the lower screen. The output end of the upper screen of the screening device (1) is connected to the soil feeding port of the water leaching device (2), the output end of the under-screen material of the lower screen of the screening device (1) is connected to the soil feeding port of the chemical oxidation remediation device (3), and the output end of the upper screen of the lower screen of the screening device (1) is connected to the soil feeding port of the chemical leaching remediation device (4).
2. The organochlorine pesticide contaminated soil remediation system according to claim 1, characterized in that: The soil outlets of the water leaching device (2), the chemical oxidation remediation device (3), and the chemical leaching remediation device (4) are all connected to the soil feeding port of the thermal desorption remediation device (5).
3. The organochlorine pesticide contaminated soil remediation system according to claim 2, characterized in that: The gas generated in the chemical rinsing repair device (4) and the thermal desorption repair device (5) is connected to the gas inlet of the gas condensing device (6) through a pipeline, and the gas outlet of the gas condensing device (6) is connected to the gas inlet of the activated carbon adsorption device (7).
4. The organochlorine pesticide contaminated soil remediation system according to claim 2, characterized in that: The soil outlet of the thermal desorption remediation device (5) is connected to the soil inlet of the thermal desorption remediation device (5).
5. The organochlorine pesticide contaminated soil remediation system according to claim 1, characterized in that: The aperture of the upper screen in the screening device (1) is less than 20 mesh, and the aperture of the lower screen in the screening device (1) is not less than 40 mesh.
6. The organochlorine pesticide contaminated soil remediation system according to claim 5, characterized in that: The screening device (1) is a shaking screen or a vibrating screen.
7. The organochlorine pesticide contaminated soil remediation system according to claim 1, characterized in that: The leaching outlet of the water leaching device (2) and the leaching outlet of the chemical leaching repair device (4) are both connected to the dosing port of the chemical oxidation device (8). The chemical oxidation device (8) is equipped with a stirring unit. The chemical oxidation device (8) is also equipped with an oxidant dosing port and a pre-activation agent dosing port. The outlet of the chemical oxidation device (8) is connected to the feeding port of the precipitation separation device (9).
8. The organochlorine pesticide contaminated soil remediation system according to claim 7, characterized in that: The liquid outlet of the sedimentation separation device (9) is connected to the liquid inlet of the water leaching device (2).