A method for repairing contaminated soil

Abstract

The present application provides a method for repairing contaminated soil, belonging to the technical field of pollutant treatment. In this method, the strong water absorption of peat soil and the porous properties and water absorption of diatomite enable the adsorption rod to generate a capillary siphon effect, adsorb persulfate in the contaminated soil, and collect the persulfate into the adsorption plate. Catalyst is regularly poured into the adsorption plate, and while adding the catalyst, the persulfate is flushed into the contaminated soil to achieve the migration of persulfate, increase the reaction opportunity with the repair agent, and achieve the repair of the contaminated soil. The method of sunning the adsorption plate can promote the crystallization of the persulfate adsorbed on the adsorption plate. After pouring water on the adsorption plate, the persulfate crystals adsorbed on the adsorption plate can be dissolved, and the persulfate is flushed into the contaminated soil to promote the migration efficiency of the persulfate. The method provided by the present application is convenient to operate. Both the adsorption rod and the adsorption plate are prepared from diatomite and peat soil, and the contaminated soil after repair will not pollute the soil during land preparation.

Description

Technical Field

[0001] The present invention belongs to the technical field of pollutant treatment and relates to a method for repairing contaminated soil. Background Art

[0002] In recent years, with the rapid development of industry, solid waste has been continuously piled and dumped on the soil surface, harmful wastewater has been continuously infiltrated into the soil, a large amount of organic pesticides, detergents, reagents, fertilizers, etc. have been used and discharged, and harmful gases and floating dust in the atmosphere have been continuously deposited on the soil with rainwater. When pollutants enter the soil and accumulate to a certain extent, it will cause the deterioration of soil quality, resulting in soil pollution, and then causing some indicators in crops to exceed the national standards, affecting human health.

[0003] At present, the methods for repairing contaminated soil mainly include chemical repair method, pyrolysis desorption repair method, composting method, phytoremediation method, and bioremediation method, etc. Among them, the advanced oxidation method in the chemical repair method shows good application prospects in the repair of pollution because the highly reactive oxygen species generated during the reaction process can oxidize and even mineralize organic pollutants without selectivity. For the advanced oxidation method, the most commonly used oxidation technology is the persulfate advanced oxidation technology with persulfate radical (SO 4 •− ) as the main oxidant. The redox potential of SO 4 •− is higher, with higher oxidizing property and better selectivity. In addition, during the oxidation and degradation of organic matter pollution by persulfate, the reactions with alkanes, alcohols, ethers, and lipid compounds are mostly hydrogen extraction, the reactions with unsaturated olefin compounds are mostly addition reactions, and the reactions with aromatic hydrocarbon compounds are mostly electron transfer. In theory, it can degrade most organic pollutants and degrade organic pollutants more thoroughly. SO 4 •− is generated by activating persulfate. There are many types of activation catalysts for activating persulfate, including alkali activation, transition metal activation, and carbon material activation, etc. These activation catalysts mainly promote the generation of SO 4 •− through the way of electron transfer.

[0004] Activating persulfate can degrade organic matter, and has the characteristics of simple operation, high activation efficiency, and no need to add chemical reagents. However, affected by factors such as poor mobility of organic pollutants and persulfate in the soil medium and small reaction opportunities, only soils with relatively high moisture content can achieve relatively high organic pollution removal effects. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for repairing contaminated soil to solve the problem that the repair effect is poor due to the poor mobility of organic pollutants and persulfate in the soil medium and small reaction opportunities when activating persulfate.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] This application provides a method for repairing contaminated soil, which includes:

[0008] S01: Prepare an adsorption rod: Crush peat soil and diatomite to a particle size of 5-10 mm respectively, add water and mix evenly to form a viscous slurry; Place the viscous slurry in a rod-shaped mold for shaping, demolding, and drying to obtain an adsorption rod; Vertically process capillary grooves on the outer periphery of the adsorption rod, the width of the capillary grooves is 0.1-2 mm, the depth is 0.1-2 mm, and the distance between adjacent two capillary grooves is 1-2 mm.

[0009] Diatomite is formed by the deposition of the remains of single-celled aquatic plants diatoms, and has properties such as special porosity, low density, large specific surface area, and stable chemical properties. The surface of diatomite is rich in hydrophilic groups such as hydroxyl groups, which can enhance the adsorption capacity for water molecules. Thus, the porous structure and water absorption performance of diatomite endow it with a siphon effect, which can adsorb persulfate in contaminated soil, and then enrich persulfate. In addition, peat soil is a kind of soil formed by the long-term decomposition of plant remains under anoxic conditions. Peat soil has abundant pores and fibrous substances, making peat soil have strong water absorption capacity. When diatomite and peat soil are used in combination, the strong water absorption capacity of peat soil enhances the ability of diatomite to adsorb persulfate, making persulfate enrich faster.

[0010] In this application, diatomite and peat soil are prepared into adsorption rods. Before preparation, the relatively large-particle peat soil and diatomite are respectively crushed to a particle size of 5-10 mm to facilitate the formation of a structurally dense adsorption rod later. After crushing, peat soil and diatomite are mixed evenly according to a mass ratio of 7:2-3, and water is added to form a viscous slurry. More preferably, the mass ratio of peat soil to diatomite is 7:3.

[0011] Fill the viscous slurry into a rod-shaped mold, fill it tightly or pat it firmly to shape the viscous slurry in the mold. After the shaped viscous slurry is demolded to form a blank, it is dried at a temperature of 50-60 °C to obtain an adsorption rod. In this application, the adsorption rod is cylindrical or columnar. When the adsorption rod is cylindrical, its diameter is 5-20 mm and its length is 200-500 mm. When the adsorption rod is columnar, its side length is 5-20 mm and its length is 200-500 mm.

[0012] Vertically process capillary grooves on the outer periphery of the adsorption rod so that a capillary siphon effect is formed on the outer periphery of the adsorption rod, thereby improving the migration rate of persulfate in the adsorption rod. For the convenience of processing, the width of the capillary groove is 0.1 - 2 mm and the depth is 0.1 - 2 mm; the distance between two adjacent capillary grooves is 1 - 2 mm.

[0013] S02: Prepare the adsorption plate: Crush peat soil and diatomite to a particle size of 5 - 10 mm respectively, add water and mix evenly to form a viscous slurry; place the viscous slurry in a plate-shaped mold for shaping, demolding, and drying to obtain the adsorption plate; N card slots are provided on the adsorption plate, and the card slots match the adsorption rod; where N is a natural number greater than 2.

[0014] Crush the peat soil and diatomite with larger particles to a particle size of 5 - 10 mm respectively to facilitate the formation of a structurally dense adsorption plate later. After crushing, mix the peat soil and diatomite evenly according to a mass ratio of 7:2 - 3, and add water to form a viscous slurry. More preferably, the mass ratio of peat soil to diatomite is 7:3.

[0015] Fill the viscous slurry into the plate-shaped mold, tamp it or pat it solid so that the viscous slurry is shaped in the mold. After the shaped viscous slurry is demolded to form a blank, dry it at a temperature of 50 - 60 °C to obtain the adsorption plate. In this application, the thickness of the adsorption plate is 3 - 5 cm, and the length and width are both set according to the number and spacing of the inserted adsorption rods. N card slots are processed on the bottom surface of the adsorption plate, and the inside of the card slots matches the outer shape of the adsorption rod so that each card slot can hold an adsorption rod. Where N is a natural number greater than 2.

[0016] S03: Prepare the catalyst: The catalyst solution includes at least one of ferrous sulfate solution, ferric sulfate solution, manganese sulfate solution, and copper sulfate solution.

[0017] In this application, the catalyst is selected from at least one of ferrous sulfate solution, ferric sulfate solution, manganese sulfate solution, and copper sulfate solution. When preparing, select at least one of ferrous sulfate, ferric sulfate, manganese sulfate, and copper sulfate, and prepare it into a solution with a concentration of 10 - 15% to form the catalyst.

[0018] S04: Add persulfate to the contaminated soil, plow the soil and mix it evenly. Among them, the mass ratio of the pollutant to the persulfate in the contaminated soil is 10:1 - 4, and the persulfate includes at least one of sodium persulfate, ammonium persulfate, and potassium persulfate.

[0019] S05: Vertically insert part of the adsorption rod into the contaminated soil, and insert an adsorption plate at the top of the N adsorption rods so that the persulfate capillary siphoned from the contaminated soil by the adsorption rod converges on the adsorption plate.

[0020] Vertically insert the vertical part of the adsorption rod into the contaminated soil, and movably insert an adsorption plate at the top of the N adsorption rods. At this time, the adsorption rod and the adsorption plate form an integral structure.

[0021] After the adsorption rod is vertically inserted into the contaminated soil, under the capillary siphon action of the soil itself and the adsorption rod, the persulfate in the contaminated soil is adsorbed into the adsorption rod and then collected upward into the adsorption plate. More preferably, the depth of the adsorption rod inserted into the contaminated soil is 2 / 3 - 3 / 4 of the height of the adsorption rod, which is more conducive to adsorbing the persulfate in the contaminated soil and the adsorption rod is not easily broken due to external environmental factors.

[0022] S06: Pour a catalyst with a concentration of 10 - 15% onto the adsorption plate every 3 - 7 days, so that the catalyst flushes the persulfate collected on the adsorption plate into the contaminated soil.

[0023] Pour a catalyst onto the adsorption plate every 3 - 7 days. The persulfate collected in the adsorption plate re - enters the contaminated soil under the flushing action of the catalyst, realizing the migration of persulfate, thereby increasing the reaction opportunity with the remediation agent and realizing the remediation of the contaminated soil. At the same time, the addition of the catalyst can activate the persulfate to generate persulfate radicals, and the persulfate radicals can react with the pollutants in the contaminated soil to achieve the purpose of soil remediation and accelerate the soil remediation process.

[0024] S07: The plate surface of the adsorption plate faces the sun. When the crystallization area of the persulfate on the adsorption plate is greater than half of the area of the adsorption plate, wash the adsorption plate with water so that the crystallized persulfate returns to the contaminated soil again.

[0025] During the process of the adsorption rod and the adsorption plate adsorbing the persulfate in the contaminated soil, a large amount of persulfate will gradually accumulate on the adsorption plate. When the water siphoned up evaporates, persulfate crystals will be formed. When the content of the persulfate crystals is too high, it will affect the rate of the adsorption rod siphoning the persulfate in the contaminated soil and the migration rate of the persulfate. Based on this, in this application, the plate surface of the adsorption plate faces the sun to promote the crystallization of the persulfate adsorbed on the adsorption plate, and then pour water onto the adsorption plate in time to dissolve the persulfate crystals on the adsorption plate, and then flush the persulfate into the contaminated soil to promote the migration efficiency of the persulfate. In this application, when the crystallization area of the persulfate on the adsorption plate is greater than half of the area of the adsorption plate, pour water onto the adsorption plate.

[0026] In this application, in order to facilitate the catalyst to flow from the unconnected part of the adsorption rod on the adsorption plate to the contaminated soil, a boss or multiple cotton threads are also provided between adjacent card slots, so that the catalyst drips along the boss or flows down along the cotton thread to the contaminated soil.

[0027] In this application, after the contaminated soil is repaired, the soil can be loosened by rotary tillage, and the adsorption rods and adsorption plates are broken up in the repaired contaminated soil. Since both the adsorption rods and adsorption plates are made of diatomite and peat soil, the soil will not be re - contaminated after being broken up and put into the repaired contaminated soil.

[0028] In addition, when peat soil is calcined at 300 - 380 °C, the loss of interlayer water will produce some small pores, resulting in an increase in specific surface area and further enhancing the water absorption performance of peat soil. Therefore, in this application, peat soil calcined at 300 - 380 °C for 2 - 5 h can be used.

[0029] Similarly, when diatomite is calcined at 750 - 900 °C, the organic matter in diatomite will be pyrolyzed, resulting in a reduction in its solid volume and an increase in porosity, thereby increasing the specific surface area of diatomite and enhancing its adsorption capacity and reactivity. Therefore, in this application, diatomite calcined at 750 - 900 °C for 2 - 5 h can be used.

[0030] The present invention has the following beneficial effects:

[0031] (1) The strong water absorption of peat soil and the porous characteristics and water absorption of diatomite enable the adsorption rods to generate a capillary siphon effect, adsorb persulfate in the contaminated soil, and collect the adsorbed persulfate into the adsorption plates. Pour the catalyst into the adsorption plates regularly, and the persulfate will re - enter the contaminated soil under the flushing action of the catalyst, realizing the migration of persulfate, thereby increasing the reaction opportunity with the repair agent and achieving the repair of the contaminated soil.

[0032] (2) By the way of sun - drying the adsorption plates, it can promote the crystallization of the persulfate adsorbed on the adsorption plates. After pouring water on the adsorption plates, the persulfate crystals adsorbed on the adsorption plates can be dissolved, and then the persulfate is flushed into the contaminated soil, promoting the migration efficiency of persulfate.

[0033] (3) Both the adsorption rods and adsorption plates are made of peat soil calcined at 300 - 380 °C and diatomite calcined at 750 - 900 °C, which can further enhance the performance of the adsorption rods and adsorption plates in adsorbing persulfate and improve the migration rate of persulfate.

[0034] (4) The outer surface of the adsorption rod is vertically provided with capillary grooves to form a capillary siphon effect on the surface of the adsorption rod through the capillary grooves, further improving the migration rate of persulfate in the adsorption rod.

[0035] (5) Both the adsorption rods and adsorption plates are made of diatomite and peat soil, and the repaired contaminated soil will not pollute the soil during land preparation. Detailed implementation manners

[0036] The technical solution of the present invention will be further explained and illustrated through specific embodiments below.

[0037] Embodiment 1

[0038] The embodiment of the present application provides a method for repairing contaminated soil, and the method includes:

[0039] S101: Prepare an adsorption rod

[0040] After respectively crushing peat soil and diatomite with larger particles to a particle size of 10 mm, mix the peat soil and diatomite evenly according to a mass ratio of 7:2, and add water to form a viscous slurry. Fill the viscous slurry into a cylindrical rod-shaped mold, fill it tightly or pat it firmly, and demold it after the viscous slurry is shaped to form a blank. The blank is dried at a temperature of 60 °C to form an adsorption rod with a diameter of 20 mm and a length of 500 mm. Vertically process capillary grooves on the outer periphery of the adsorption rod, the width of the capillary grooves is 2 mm, and the depth is 2 mm; the distance between adjacent two capillary grooves is 2 mm.

[0041] S102: Prepare an adsorption plate

[0042] After respectively crushing peat soil and diatomite with larger particles to a particle size of 10 mm, mix the peat soil and diatomite evenly according to a mass ratio of 7:2, and add water to form a viscous slurry. Fill the viscous slurry into a plate-shaped mold, fill it tightly or pat it firmly, and demold it after the viscous slurry is shaped to form a blank. The blank is dried at a temperature of 60 °C to form an adsorption plate with a thickness of 5 cm, a width of 40 cm, and a length of 40 cm. Four card slots are processed on the bottom surface of the adsorption plate so that an adsorption rod can be clamped in each card slot.

[0043] S103: Prepare a catalyst

[0044] Prepare a solution of ferrous sulfate with a concentration of 15% to form a catalyst.

[0045] S104: Add sodium persulfate to the contaminated soil, turn over the soil and mix it evenly, wherein the mass ratio of the pollutants in the contaminated soil to the persulfate is 10:4.

[0046] Vertically insert part of the adsorption rod into the contaminated soil, and the depth of the adsorption rod inserted into the contaminated soil is 3 / 4 of the height of the adsorption rod. Actively insert an adsorption plate at the top of the four adsorption rods. At this time, the adsorption rod and the adsorption plate form an integral structure. When the adsorption rod is vertically inserted into the contaminated soil, under the capillary siphon action of the soil itself and the capillary siphon action of the adsorption rod, the sodium persulfate in the contaminated soil is adsorbed into the adsorption rod and then collected into the adsorption plate from bottom to top.

[0047] S106: Pour the catalyst onto the adsorption plate every seven days. The sodium persulfate that has gathered on the adsorption plate re-enters the contaminated soil under the flushing action of the catalyst.

[0048] S107: Face the surface of the adsorption plate towards the sun. When the crystallization area of the sodium persulfate on the adsorption plate is greater than half of the area of the adsorption plate, rinse the adsorption plate with water so that the crystallized sodium persulfate returns to the contaminated soil again.

[0049] Example 2

[0050] The embodiment of the present application provides a method for repairing contaminated soil, and the method includes:

[0051] S201: Prepare adsorption rods

[0052] After respectively crushing the peat soil and diatomite with larger particle sizes to a particle size of 5 mm, mix the peat soil and diatomite evenly according to a mass ratio of 7:3, and add water to form a viscous slurry. Fill the viscous slurry into a columnar rod-shaped mold, tamp or pat it firmly. After the viscous slurry is shaped, demold it to form a blank. The blank is dried at a temperature of 50 °C to form an adsorption rod with a side length of 20 mm and a length of 500 mm. Vertically process capillary grooves on the outer periphery of the adsorption rod, and the width of the capillary grooves is 0.1 mm and the depth is 0.1 mm; the distance between two adjacent capillary grooves is 1 mm.

[0053] S202: Prepare adsorption plates

[0054] After respectively crushing the peat soil and diatomite with larger particle sizes to a particle size of 5 mm, mix the peat soil and diatomite evenly according to a mass ratio of 7:3, and add water to form a viscous slurry. Fill the viscous slurry into a plate-shaped mold, tamp or pat it firmly. After the viscous slurry is shaped, demold it to form a blank. The blank is dried at a temperature of 50 °C to form an adsorption plate with a thickness of 3 cm, a width of 40 cm, and a length of 60 cm. Six card slots are processed on the bottom surface of the adsorption plate so that an adsorption rod can be clamped in each card slot.

[0055] S203: Prepare the catalyst

[0056] Prepare ferric sulfate into a solution with a concentration of 10% to form the catalyst.

[0057] S204: Add ammonium persulfate to the contaminated soil, plow the land and mix it evenly. Among them, the mass ratio of the pollutants in the contaminated soil to the persulfate is 10:1.

[0058] S205: Vertically insert the adsorption rod into the contaminated soil. The depth of the adsorption rod inserted into the contaminated soil is 2 / 3 of the height of the adsorption rod. At the top of the six adsorption rods, an adsorption plate is movably inserted. At this time, the adsorption rod and the adsorption plate form an integral structure. After the adsorption rod is vertically inserted into the contaminated soil, under the capillary siphon action of the soil itself and the adsorption rod, ammonium persulfate in the contaminated soil is adsorbed into the adsorption rod and then collected upward into the adsorption plate.

[0059] S206: Pour the catalyst onto the adsorption plate every three days. The ammonium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing action of the catalyst.

[0060] S207: Face the surface of the adsorption plate towards the sun. When the crystallization area of ammonium persulfate on the adsorption plate is greater than half of the area of the adsorption plate, wash the adsorption plate with water so that the crystallized ammonium persulfate returns to the contaminated soil again.

[0061] Example 3

[0062] The embodiment of the present application provides a method for repairing contaminated soil, and the method includes:

[0063] S301: Prepare the adsorption rod

[0064] After respectively crushing the peat soil and diatomite with larger particles to a particle size of 6 mm, mix the peat soil and diatomite evenly according to a mass ratio of 7:3, and add water to form a viscous slurry. Fill the viscous slurry into a columnar rod-shaped mold, tamp or pat it firmly. After the viscous slurry is shaped, demold it to form a blank. The blank is dried at a temperature of 55 °C to form an adsorption rod with a side length of 15 mm and a length of 400 mm. Vertically process capillary grooves on the outer periphery of the adsorption rod. The width of the capillary groove is 1 mm and the depth is 1 mm; the distance between adjacent two capillary grooves is 1.5 mm.

[0065] S302: Prepare the adsorption plate

[0066] After respectively crushing the peat soil and diatomite with larger particles to a particle size of 6 mm, mix the peat soil and diatomite evenly according to a mass ratio of 7:3, and add water to form a viscous slurry. Fill the viscous slurry into a plate-shaped mold, tamp or pat it firmly. After the viscous slurry is shaped, demold it to form a blank. The blank is dried at a temperature of 55 °C to form an adsorption plate with a thickness of 4 cm, a width of 40 cm, and a length of 60 cm. Six card slots are processed on the bottom surface of the adsorption plate so that each card slot can be used to clamp an adsorption rod.

[0067] S303: Prepare the catalyst

[0068] Prepare ferrous sulfate into a solution with a concentration of 12% to form a catalyst.

[0069] S304: Add potassium persulfate to the contaminated soil, turn over the soil and mix it evenly. Among them, the mass ratio of the pollutants in the contaminated soil to the persulfate is 10:3.

[0070] S305: Vertically insert the adsorption rod into the contaminated soil. The depth of the adsorption rod inserted into the contaminated soil is 3 / 4 of the height of the adsorption rod. A movable adsorption plate is inserted at the top of the 6 adsorption rods. At this time, the adsorption rod and the adsorption plate form an integral structure. When the adsorption rod is vertically inserted into the contaminated soil, under the capillary siphon action of the soil itself and the capillary siphon action of the adsorption rod, the potassium persulfate in the contaminated soil is adsorbed into the adsorption rod and then collected upward into the adsorption plate.

[0071] S306: Pour the catalyst onto the adsorption plate every 5 days. The potassium persulfate collected in the adsorption plate re-enters the contaminated soil under the flushing action of the catalyst.

[0072] S307: Face the plate surface of the adsorption plate towards the sun. When the crystallization area of the potassium persulfate on the adsorption plate is greater than half of the area of the adsorption plate, wash the adsorption plate with water so that the crystallized potassium persulfate returns to the contaminated soil again.

[0073] Example 4

[0074] The embodiment of the present application provides a method for repairing contaminated soil, and this method includes:

[0075] S401: Prepare the adsorption rod

[0076] After respectively crushing the peat soil and diatomite with larger particles to a particle size of 6 mm, mix the peat soil and diatomite evenly according to a mass ratio of 7:3, add water to form a viscous slurry. Fill the viscous slurry into a columnar rod-shaped mold, fill it tightly or pat it firmly, and demold after the viscous slurry is shaped to form a blank. The blank is dried at a temperature of 55 °C to form an adsorption rod with a diameter of 15 mm and a length of 400 mm. Vertically process capillary grooves on the outer periphery of the adsorption rod. The width of the capillary grooves is 1 mm and the depth is 1 mm; the distance between two adjacent capillary grooves is 1.5 mm.

[0077] S402: Prepare the adsorption plate

[0078] After separately crushing peat soil and diatomite with larger particle sizes to a particle size of 6 mm, the peat soil and diatomite are mixed evenly according to a mass ratio of 7:3, and water is added to form a viscous slurry. The viscous slurry is filled into a plate-shaped mold, filled or tamped firmly, and after the viscous slurry is shaped, it is demolded to form a blank. The blank is dried at a temperature of 55 °C to form an adsorption plate with a thickness of 4 cm, a width of 40 cm, and a length of 60 cm. N card slots are processed on the bottom surface of the adsorption plate so that an adsorption rod can be clamped in each card slot. At the same time, cotton threads are arranged between two adjacent card slots so that the catalyst can flow along the cotton threads into the contaminated soil.

[0079] S403: Prepare the catalyst

[0080] Ferrous sulfate is prepared into a solution with a concentration of 12% to form a catalyst.

[0081] S404: Add potassium persulfate to the contaminated soil, plow the land and mix evenly, wherein the mass ratio of the pollutants in the contaminated soil to the persulfate is 10:3.

[0082] S405: Vertically insert the vertical part of the adsorption rod into the contaminated soil, and the depth of the adsorption rod inserted into the contaminated soil is 3 / 4 of the height of the adsorption rod. An adsorption plate is movably inserted at the top of the N adsorption rods. At this time, the adsorption rod and the adsorption plate form an integral structure. When the adsorption rod is vertically inserted into the contaminated soil, under the capillary siphon action of the soil itself and the capillary siphon action of the adsorption rod, the potassium persulfate in the contaminated soil is adsorbed into the adsorption rod and then collected from bottom to top into the adsorption plate.

[0083] S406: Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate collected in the adsorption plate re-enters the contaminated soil under the flushing action of the catalyst.

[0084] S407: Face the plate surface of the adsorption plate towards the sun. When the crystallization area of the potassium persulfate on the adsorption plate is greater than half of the area of the adsorption plate, wash the adsorption plate with water so that the crystallized potassium persulfate returns to the contaminated soil again.

[0085] Example 5

[0086] The embodiment of the present application provides a method for repairing contaminated soil, and the method includes:

[0087] S501: Prepare the adsorption rod

[0088] Calcine peat soil at 380°C for 2 h to obtain calcined peat soil. Calcine diatomite at 900°C for 2 h to obtain calcined diatomite. After crushing the calcined peat soil and the calcined diatomite to a particle size of 6 mm respectively, mix the calcined peat soil and the calcined diatomite evenly according to a mass ratio of 7:3, and add water to form a viscous slurry. Fill the viscous slurry into a columnar rod-shaped mold, tamp or pat it firmly. After the viscous slurry is shaped, demold it to form a green body. Dry the green body at a temperature of 55°C to form an adsorption rod with a side length of 15 mm and a length of 400 mm. Vertically process capillary grooves on the outer periphery of the adsorption rod, the width of the capillary grooves is 1 mm and the depth is 1 mm; the distance between adjacent two capillary grooves is 1.5 mm.

[0089] S502: Prepare an adsorption plate

[0090] Calcine peat soil at 380°C for 2 h to obtain calcined peat soil. Calcine diatomite at 900°C for 2 h to obtain calcined diatomite. After crushing the calcined peat soil and the calcined diatomite to a particle size of 6 mm respectively, mix the calcined peat soil and the calcined diatomite evenly according to a mass ratio of 7:3, and add water to form a viscous slurry. Fill the viscous slurry into a plate-shaped mold, tamp or pat it firmly. After the viscous slurry is shaped, demold it to form a green body. Dry the green body at a temperature of 55°C to form an adsorption plate with a thickness of 4 cm, a width of 40 cm and a length of 60 cm. Process 6 card slots on the bottom surface of the adsorption plate so that an adsorption rod can be clamped in each card slot. At the same time, arrange cotton threads between adjacent two card slots so that the catalyst can flow along the cotton threads into the polluted soil.

[0091] S503: Prepare a catalyst

[0092] Prepare ferrous sulfate into a solution with a concentration of 12% to form a catalyst.

[0093] S504: Add potassium persulfate to the polluted soil, plow the soil and mix it evenly, wherein the mass ratio of the pollutants in the polluted soil to the persulfate is 10:3.

[0094] Vertically insert part of the adsorption rod into the polluted soil, and the depth of the adsorption rod inserted into the polluted soil is 3 / 4 of the height of the adsorption rod. Actively insert an adsorption plate at the top of the 6 adsorption rods. At this time, the adsorption rod and the adsorption plate form an integral structure. When the adsorption rod is vertically inserted into the polluted soil, under the capillary siphon action of the soil itself and the capillary siphon action of the adsorption rod, the potassium persulfate in the polluted soil is adsorbed into the adsorption rod and then converges from bottom to top into the adsorption plate.

[0095] Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate converged into the adsorption plate re-enters the polluted soil under the flushing action of the catalyst.

[0096] S507: Face the surface of the adsorption plate towards sunlight. When the crystallization area of potassium persulfate on the adsorption plate is greater than half of the area of the adsorption plate, rinse the adsorption plate with water so that the crystallized potassium persulfate returns to the contaminated soil again.

[0097] Example 6

[0098] An embodiment of the present application provides a method for repairing contaminated soil, and the method includes:

[0099] S601: Prepare an adsorption rod

[0100] Calcine peat soil at 300°C for 5 h to obtain calcined peat soil. Calcine diatomite at 750°C for 5 h to obtain calcined diatomite. After crushing the calcined peat soil and the calcined diatomite to a particle size of 6 mm respectively, mix the calcined peat soil and the calcined diatomite evenly according to a mass ratio of 7:3, add water to form a viscous slurry. Fill the viscous slurry into a columnar rod-shaped mold, fill it tightly or pat it firmly, and demold after the viscous slurry is shaped to form a blank. Dry the blank at a temperature of 55°C to form an adsorption rod with a side length of 15 mm and a length of 400 mm. Vertically process capillary grooves on the outer periphery of the adsorption rod, the width of the capillary grooves is 1 mm and the depth is 1 mm; the distance between two adjacent capillary grooves is 1.5 mm.

[0101] S602: Prepare an adsorption plate

[0102] Calcine peat soil at 300°C for 5 h to obtain calcined peat soil. Calcine diatomite at 750°C for 5 h to obtain calcined diatomite. After crushing the calcined peat soil and the calcined diatomite to a particle size of 6 mm respectively, mix the calcined peat soil and the calcined diatomite evenly according to a mass ratio of 7:3, add water to form a viscous slurry. Fill the viscous slurry into a plate-shaped mold, fill it tightly or pat it firmly, and demold after the viscous slurry is shaped to form a blank. Dry the blank at a temperature of 55°C to form an adsorption plate with a thickness of 4 cm, a width of 40 cm, and a length of 60 cm. Six card slots are processed on the bottom surface of the adsorption plate so that an adsorption rod can be clamped in each card slot. At the same time, cotton threads are arranged between two adjacent card slots so that the catalyst can flow along the cotton threads to the contaminated soil.

[0103] S603: Prepare a catalyst

[0104] Prepare ferrous sulfate into a solution with a concentration of 12% to form a catalyst.

[0105] Add potassium persulfate to the contaminated soil, plow the land and mix it evenly, wherein the mass ratio of the pollutants in the contaminated soil to the persulfate is 10:3.

[0106] S605: Vertically insert the adsorption rod into the contaminated soil, and the depth of the adsorption rod inserted into the contaminated soil is 3 / 4 of the height of the adsorption rod. At the top of the 6 adsorption rods, an adsorption plate is movably inserted. At this time, the adsorption rod and the adsorption plate form an integral structure. After the adsorption rod is vertically inserted into the contaminated soil, under the capillary siphon action of the soil itself and the capillary siphon action of the adsorption rod, potassium persulfate in the contaminated soil is adsorbed into the adsorption rod and then collected upward into the adsorption plate.

[0107] S606: Pour the catalyst onto the adsorption plate every 5 days. The potassium persulfate collected in the adsorption plate re-enters the contaminated soil under the flushing action of the catalyst.

[0108] S607: Face the plate surface of the adsorption plate towards the sun. When the crystallization area of potassium persulfate on the adsorption plate is greater than half of the area of the adsorption plate, wash the adsorption plate with water so that the crystallized potassium persulfate returns to the contaminated soil again.

[0109] Example 7

[0110] The embodiment of the present application provides a method for repairing contaminated soil, and the method includes:

[0111] S701: Prepare the adsorption rod

[0112] Calcine peat soil at 350 °C for 3 h to obtain calcined peat soil. Calcine diatomite at 800 °C for 3 h to obtain calcined diatomite. After crushing the calcined peat soil and the calcined diatomite to a particle size of 6 mm respectively, mix the calcined peat soil and the calcined diatomite evenly according to a mass ratio of 7:3, add water to form a viscous slurry. Fill the viscous slurry into a columnar rod-shaped mold, fill it tightly or pat it firmly, and demold after the viscous slurry is shaped to form a blank. The blank is dried at a temperature of 55 °C to form an adsorption rod with a side length of 15 mm and a length of 400 mm. Vertically process capillary grooves on the outer periphery of the adsorption rod, the width of the capillary grooves is 1 mm, and the depth is 1 mm; the distance between two adjacent capillary grooves is 1.5 mm.

[0113] S702: Prepare the adsorption plate

[0114] Calcine peat soil at 350 °C for 3 h to obtain calcined peat soil. Calcine diatomite at 800 °C for 3 h to obtain calcined diatomite. After crushing the calcined peat soil and the calcined diatomite to a particle size of 6 mm respectively, mix the calcined peat soil and the calcined diatomite evenly according to a mass ratio of 7:3, and add water to form a viscous slurry. Fill the viscous slurry into a plate-shaped mold, tamp or pat it firmly. After the viscous slurry is shaped, demold it to form a blank. Dry the blank at a temperature of 55 °C to form an adsorption plate with a thickness of 4 cm, a width of 40 cm, and a length of 60 cm. Six card slots are processed on the bottom surface of the adsorption plate so that an adsorption rod can be clamped in each card slot. At the same time, cotton threads are arranged between two adjacent card slots so that the catalyst can flow along the cotton threads into the polluted soil.

[0115] S703: Prepare the catalyst

[0116] Prepare a solution of ferrous sulfate with a concentration of 12% to form a catalyst.

[0117] S704: Add potassium persulfate to the polluted soil, plow the soil and mix it evenly, wherein the mass ratio of the pollutants in the polluted soil to the persulfate is 10:3.

[0118] Vertically insert the vertical part of the adsorption rod into the polluted soil, and the depth of the adsorption rod inserted into the polluted soil is 3 / 4 of the height of the adsorption rod. A movable plug connection of an adsorption plate is made at the top of the six adsorption rods. At this time, the adsorption rod and the adsorption plate form an integral structure. When the adsorption rod is vertically inserted into the polluted soil, under the capillary siphon action of the soil itself and the capillary siphon action of the adsorption rod, the potassium persulfate in the polluted soil is adsorbed into the adsorption rod and then collected upward into the adsorption plate.

[0119] Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate collected in the adsorption plate re-enters the polluted soil under the flushing action of the catalyst.

[0120] Face the plate surface of the adsorption plate towards the sun. When the crystallization area of potassium persulfate on the adsorption plate is greater than half of the area of the adsorption plate, wash the adsorption plate with water so that the crystallized potassium persulfate returns to the polluted soil again.

[0121] Apply the methods shown in Examples 3, 4, and 7 to the same polluted soil respectively. Before inserting the adsorption rod into the polluted soil, detect the contents (mg / kg) of Cd, Pb, As, and Cr in the soil at soil depths of 5 cm, 10 cm, 20 cm, 30 cm, and 40 cm along the vertical direction of the soil respectively. The detection results are shown in Table 1. One and a half years after applying the methods shown in Examples 3, 4, and 7 to the above polluted soil, detect the heavy metal contents at different vertical depths of the soil respectively, as shown in Table 2.

[0122] Table 1: Heavy Metal Contents in Contaminated Soils at Different Depths (mg / kg)

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[0124] Table 2: Heavy Metal Contents in Contaminated Soils after Treatment by the Methods of Examples 3, 4, and 7 (mg / kg)

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[0126] According to the content in Tables 1 and 2, after the contaminated soil is repaired by the repair methods of Examples 3, 4, and 7, the contents of various heavy metals in the soil are greatly reduced.

[0127] Comparing the repair methods of Examples 3 and 4, it can be seen that, compared with the setting in Example 3 where no cotton thread is added to the adsorption plate, after adding cotton thread to the adsorption plate in Example 4, the contents of various heavy metals in the soil are lower. This indicates that the catalyst flushing and water flushing can greatly improve the migration efficiency of persulfate and increase the soil repair rate.

[0128] Comparing the repair methods of Examples 4 and 7, it can be seen that, compared with the adsorption rods and adsorption plates prepared from untreated peat soil and diatomite in Example 4, after using the peat soil and diatomite calcined at high temperature in Example 7, the contents of various heavy metals in the soil are greatly reduced. This indicates that the adsorption rods and adsorption plates prepared from the peat soil and diatomite calcined at high temperature have higher adsorption capacity and water absorption, and further improve the migration efficiency of persulfate and increase the soil repair rate.

[0129] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for remediating contaminated soil, characterized in that: include: Preparation of adsorption rods: crush peat soil and diatomaceous earth to a particle size of 5-10 mm, add water and mix evenly to form a viscous mud; The viscous slurry is placed in a rod-shaped model for shaping, demolding, and drying to obtain an adsorption rod; capillary grooves are vertically processed on the periphery of the adsorption rod, the width of the capillary grooves is 0.1-2 mm, the depth is 0.1-2 mm, and the distance between two adjacent capillary grooves is 1-2 mm; Preparation of adsorption board: Peat soil and diatomaceous earth are crushed to particle size of 5-10 mm respectively, and water is added to mix evenly to form viscous mud; the viscous mud is placed in a plate-shaped mold for shaping, demolding, and drying to obtain an adsorption board; the adsorption board is provided with N card slots, and the card slots match the adsorption rods; wherein N is a natural number greater than 2; Preparing a catalyst: the catalyst solution includes at least one of a ferrous sulfate solution, a ferric sulfate solution, a manganese sulfate solution and a copper sulfate solution; Add persulfate to the contaminated soil, turn the soil over and mix well; Inserting the vertical part of the adsorption rod into the contaminated soil, and inserting one adsorption plate at the top of N adsorption rods, so that the persulfate siphoned from the contaminated soil by the adsorption rod is collected on the adsorption plate; Pour a catalyst having a concentration of 10-15% onto the adsorption plate every 3-7 days, so that the catalyst can wash the persulfate collected on the adsorption plate into the contaminated soil; The surface of the adsorption plate faces the sunlight. When the crystallization area of ​​the persulfate on the adsorption plate is greater than half of the area of ​​the adsorption plate, the adsorption plate is washed with water to allow the crystallized persulfate to return to the contaminated soil.

2. The method for remediating contaminated soil according to claim 1, characterized in that: The mass ratio of peat soil to diatomaceous earth is 7:2-3.

3. The method for remediating contaminated soil according to claim 1, characterized in that: The mass ratio of pollutants to persulfate in the contaminated soil is 10:1-4.

4. The method for remediating contaminated soil according to claim 1, characterized in that: The persulfate includes at least one of sodium persulfate, ammonium persulfate and potassium persulfate.

5. The method for remediating contaminated soil according to claim 1, characterized in that: The depth of the adsorption rod inserted into the contaminated soil is 2 / 3-3 / 4 of the height of the adsorption rod.

6. The method for remediating contaminated soil according to claim 1, characterized in that: A boss or a plurality of cotton threads are also provided between two adjacent slots.

7. The method for remediating contaminated soil according to claim 1, characterized in that: The peat soil is calcined peat soil, and the calcination temperature is 300-380°C.

8. The method for remediating contaminated soil according to claim 1, characterized in that: The diatomaceous earth is calcined diatomaceous earth, and the calcination temperature is 750-900°C.

9. The method for remediating contaminated soil according to claim 1, characterized in that: The adsorption rod is cylindrical, and has a diameter of 5-20 mm and a length of 200-500 mm.

10. The method for remediating contaminated soil according to claim 1, characterized in that: The adsorption rod is in the shape of a column, and the side length of the adsorption rod is 5-20 mm and the length is 200-500 mm.

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