Method for repairing polluted soil

Abstract

The invention provides a method for repairing polluted soil, and belongs to the technical field of pollutant treatment. According to the method, due to the strong water absorption property of peat soil and the porous characteristic and water absorption property of diatomite, an adsorption rod generates a capillary siphon effect to adsorb persulfate in the polluted soil, and the persulfate is collected into an adsorption plate. And a catalyst is poured into the adsorption plate regularly, persulfate is washed into the contaminated soil while the catalyst is added, migration of the persulfate is achieved, the opportunity of reaction with the remediation agent is increased, and remediation of the contaminated soil is achieved. And the persulfate adsorbed on the adsorption plate can be promoted to crystallize in a manner of drying the adsorption plate in the sun. After water is poured on the adsorption plate, persulfate crystals on the adsorption plate can be dissolved, the persulfate is washed into the polluted soil, and the migration efficiency of the persulfate is promoted. The method provided by the invention is convenient to operate, the adsorption rods and the adsorption plates are prepared from diatomite and peat soil, and the repaired polluted soil cannot pollute the soil during soil preparation.

Description

Technical Field

[0001] The 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 infiltrating into the soil, and large amounts of organic pesticides, detergents, reagents, fertilizers, etc. have been used and discharged. Harmful gases and floating dust in the atmosphere have been continuously falling into the soil with rainwater. When pollutants enter the soil and accumulate to a certain extent, it will cause the soil quality to deteriorate, leading to soil pollution, and then causing certain indicators of crops to exceed national standards, affecting human health.

[0003] At present, the methods for remediating contaminated soil mainly include chemical remediation, thermal desorption remediation, composting, phytoremediation and bioremediation. Among them, the advanced oxidation method in chemical remediation shows good application prospects in pollution remediation because the highly active oxygen species produced during the reaction process will non-selectively oxidize or even mineralize organic pollutants. For the advanced oxidation method, the most commonly used oxidation technology is the persulfate free radical (SO4 •− ) is the main oxidant persulfate advanced oxidation technology. SO4 •− The redox potential of persulfate is higher, and it has higher oxidizability and better selectivity. In addition, in the process of oxidative degradation of organic pollution, the reactions of persulfate 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 the degradation of organic pollutants is more thorough. SO4 •− It is produced by activating persulfate. There are many types of activation catalysts for activating persulfate, including alkali activation, transition metal activation, and carbon material activation. These activation catalysts mainly promote persulfate to generate SO4•− by electron transfer.

[0004] Activated persulfate can degrade organic matter, and has the characteristics of simple operation, high activation efficiency, and no need to add chemical reagents. However, due to the poor mobility of organic pollutants and persulfate in the soil medium and the small reaction opportunity, soil with a higher water content can often achieve a higher organic pollution removal effect. 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 activated persulfate is affected by the poor mobility of organic pollutants and persulfate in the soil medium and the small reaction opportunity, resulting in poor repair effect.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a method for remediating contaminated soil, the method comprising: S01: Prepare 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; place the viscous mud in a rod-shaped model for shaping, demolding, and drying to obtain an adsorption rod; vertically process capillary grooves 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.

[0007] Diatomaceous earth is formed by the sedimentation of the remains of unicellular aquatic plants diatoms. It has special porosity, low density, large specific surface area, stable chemical properties and other properties. The surface of diatomaceous earth is rich in hydrophilic groups such as hydroxyl groups, which can enhance the adsorption capacity of water molecules. Therefore, the porous structure and water absorption properties of diatomaceous earth give it a siphon effect, which can adsorb persulfate in contaminated soil, thereby enriching persulfate. In addition, peat soil is a kind of soil formed by the long-term decomposition of plant remains under anaerobic conditions. Peat soil has abundant pores and fibrous substances, which makes peat soil have a strong water absorption capacity. When diatomaceous earth and peat soil are mixed, the strong water absorption capacity of peat soil enhances the ability of diatomaceous earth to adsorb persulfate, making persulfate enriched faster.

[0008] In the present application, diatomaceous earth and peat are prepared into adsorption rods. Before preparation, the peat and diatomaceous earth with larger particles are crushed to a particle size of 5-10 mm, respectively, so as to form a dense adsorption rod in the later stage. After crushing, the peat and diatomaceous earth are evenly mixed in a mass ratio of 7:2-3, and water is added to form a viscous mud. Preferably, the mass ratio of peat and diatomaceous earth is 7:3.

[0009] The viscous mud is filled into a rod-shaped mold, and is filled or compacted to shape the viscous mud in the mold. After the shaped viscous mud is demolded to form a tire blank, it is dried at a temperature of 50-60° C. to obtain an adsorption rod. In the present 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.

[0010] Capillary grooves are processed vertically on the periphery of the adsorption rod to form a capillary siphon effect on the periphery of the adsorption rod, thereby increasing the migration rate of persulfate in the adsorption rod. For ease of processing, the width of the capillary groove is 0.1-2mm and the depth is 0.1-2mm; the distance between two adjacent capillary grooves is 1-2mm.

[0011] S02: Prepare an adsorption plate: crush peat soil and diatomaceous earth to a particle size of 5-10 mm respectively, add water and mix evenly to form a viscous mud; place the viscous mud in a plate-shaped mold for shaping, demolding, and drying to obtain an adsorption plate; the adsorption plate is provided with N card slots, and the card slots match the adsorption rods; wherein N is a natural number greater than 2.

[0012] The peat and diatomaceous earth with larger particles are crushed to a particle size of 5-10 mm respectively, so as to form a dense adsorption board in the later stage. After crushing, the peat and diatomaceous earth are evenly mixed in a mass ratio of 7:2-3, and water is added to form a viscous mud. Preferably, the mass ratio of peat and diatomaceous earth is 7:3.

[0013] Fill the viscous mud into a plate-shaped mold, fill or pat it to shape the viscous mud in the mold. After the shaped viscous mud is demolded to form a tire blank, it is dried at a temperature of 50-60°C to obtain an adsorption plate. In the present application, the thickness of the adsorption plate is 3-5cm, and the length and width are 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 interior of the card slot matches the shape of the adsorption rod so that an adsorption rod can be clamped in each card slot. Among them, N is a natural number greater than 2.

[0014] S03: preparing a catalyst: the catalyst solution comprises at least one of a ferrous sulfate solution, a ferric sulfate solution, a manganese sulfate solution and a copper sulfate solution.

[0015] In the present application, the catalyst is selected from at least one of ferrous sulfate solution, ferric sulfate solution, manganese sulfate solution and copper sulfate solution. During preparation, at least one of ferrous sulfate, ferric sulfate, manganese sulfate and copper sulfate is selected and prepared into a solution with a concentration of 10-15% to form a catalyst.

[0016] S04: adding persulfate to the contaminated soil, turning the soil and mixing. The mass ratio of the pollutants in the contaminated soil to the persulfate is 10:1-4, and the persulfate includes at least one of sodium persulfate, ammonium persulfate and potassium persulfate.

[0017] S05: inserting the vertical part of the adsorption rod into the contaminated soil, and plugging one of the adsorption plates at the top ends of the N adsorption rods, so that the persulfate siphoned from the contaminated soil by the adsorption rods is collected on the adsorption plate.

[0018] The vertical part of the adsorption rod is inserted into the contaminated soil, and an adsorption plate is movably plugged into the top of the N adsorption rods. At this time, the adsorption rod and the adsorption plate form an integral structure.

[0019] When the adsorption rod is vertically inserted into the contaminated soil, the persulfate in the contaminated soil is adsorbed into the adsorption rod under the capillary siphon effect of the soil itself and the capillary siphon effect of the adsorption rod, and then collected from bottom to top into the adsorption plate. 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 the adsorption of persulfate in the contaminated soil, and the adsorption rod is not easily broken due to external environmental factors.

[0020] S06: pouring a catalyst with 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.

[0021] Pour the catalyst onto the adsorption plate every 3-7 days, and the persulfate collected on the adsorption plate will re-enter the contaminated soil under the flushing effect of the catalyst, achieving the migration of the persulfate, thereby increasing the chance of reaction with the repair agent and achieving the repair of the contaminated soil. At the same time, the addition of the catalyst can activate the persulfate to produce persulfate radicals, which can react with pollutants in the contaminated soil to achieve the purpose of repairing the soil and accelerate the soil repair process.

[0022] S07: 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.

[0023] During the process of adsorption rod and adsorption plate adsorbing persulfate in contaminated soil, a large amount of persulfate will gradually accumulate on the adsorption plate, and when the water siphoned up evaporates, persulfate crystals will be formed. When the content of persulfate crystals is too much, the rate of persulfate in the contaminated soil of the adsorption rod siphon will be affected, affecting the migration rate of persulfate. Based on this, in this application, the plate surface of the adsorption plate is facing the sunlight, promoting the persulfate crystals adsorbed on the adsorption plate, and then pouring water on the adsorption plate in time to dissolve the persulfate crystals on the adsorption plate, and then persulfate is rinsed into the contaminated soil, promoting the migration efficiency of persulfate. In this application, when the crystallization area of ​​the persulfate on the adsorption plate is greater than half of the adsorption plate area, pour water on the adsorption plate.

[0024] In the present application, in order to facilitate the catalyst to flow from the adsorption plate where the adsorption rod is not connected to the contaminated soil, a boss or multiple cotton threads are provided between two adjacent slots to allow the catalyst to drip along the boss or flow along the cotton threads into the contaminated soil.

[0025] In the present application, after the contaminated soil is repaired, the soil can be loosened by rotary tillage, and the adsorption rods and adsorption plates can be broken into the repaired contaminated soil. Since the adsorption rods and adsorption plates are made of diatomaceous earth and peat soil, the soil will not be contaminated again after being broken into the repaired contaminated soil.

[0026] 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, further increasing the water absorption capacity of peat soil. Therefore, peat soil calcined at 300-380°C for 2-5 hours can be used in this application.

[0027] Similarly, when diatomaceous earth is calcined at 750-900°C, the organic matter in the diatomaceous earth will be pyrolyzed, resulting in a decrease in its solid volume and an increase in porosity, thereby increasing the specific surface area of ​​the diatomaceous earth and improving its adsorption capacity and reactivity. Therefore, diatomaceous earth calcined at 750-900°C for 2-5h can be used in this application.

[0028] The present invention has the following beneficial effects: (1) The strong water absorption of peat soil and the porous characteristics and water absorption of diatomaceous earth enable the adsorption rod to produce a capillary siphon effect, adsorbing persulfate in the contaminated soil and collecting the adsorbed persulfate into the adsorption plate. The catalyst is poured into the adsorption plate regularly, and the persulfate re-enters the contaminated soil under the flushing effect of the catalyst, realizing the migration of persulfate, thereby increasing the reaction opportunity with the repair agent and realizing the repair of the contaminated soil.

[0029] (2) Exposing the adsorption plate to sunlight can promote the crystallization of persulfate adsorbed on the adsorption plate. When water is poured on the adsorption plate, the persulfate crystals on the adsorption plate can be dissolved, and then the persulfate can be washed into the contaminated soil, promoting the migration efficiency of the persulfate.

[0030] (3) Both the adsorption rod and the adsorption plate are made of peat soil calcined at 300-380°C and diatomaceous earth calcined at 750-900°C, which can further enhance the adsorption performance of the adsorption rod and the adsorption plate for persulfate and increase the migration rate of persulfate.

[0031] (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, thereby further increasing the migration rate of persulfate in the adsorption rod.

[0032] (5) Both the adsorption rods and adsorption plates are made of diatomaceous earth and peat soil. The repaired contaminated soil will not pollute the soil during land preparation. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0034] Example 1 The present invention provides a method for remediating contaminated soil, the method comprising: S101: Preparation of adsorption rods After the peat and diatomaceous earth with larger particles are crushed to a particle size of 10mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:2, and water is added to form a viscous mud. The viscous mud is filled into a cylindrical rod-shaped mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire blank is dried at a temperature of 60°C to form an adsorption rod with a diameter of 20mm and a length of 500mm. Capillary grooves are vertically processed on the periphery of the adsorption rod, and the width and depth of the capillary grooves are 2mm; the distance between two adjacent capillary grooves is 2mm.

[0035] S102: Preparation of adsorption plate After the peat and diatomaceous earth with larger particles are crushed to a particle size of 10 mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:2, and water is added to form a viscous mud. The viscous mud is filled into a plate-shaped mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire 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.

[0036] S103: Catalyst preparation Ferrous sulfate is prepared into a 15% solution to form a catalyst.

[0037] S104: adding sodium persulfate to the contaminated soil, turning the soil and mixing it evenly, wherein the mass ratio of the pollutants to the persulfate in the contaminated soil is 10:4.

[0038] S105: Insert the adsorption rod vertically 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 connected to the top of the four adsorption rods, and 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 effect of the soil itself and the capillary siphon effect 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.

[0039] S106: Pour a catalyst onto the adsorption plate every 7 days, and the sodium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing effect of the catalyst.

[0040] S107: The adsorption plate is placed facing the sunlight. When the crystallized area of ​​sodium persulfate on the adsorption plate is larger than half of the area of ​​the adsorption plate, the adsorption plate is washed with water to return the crystallized sodium persulfate to the contaminated soil.

[0041] Example 2 The present invention provides a method for remediating contaminated soil, the method comprising: S201: Preparation of adsorption rods After the peat and diatomaceous earth with larger particles are crushed to a particle size of 5mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:3, and water is added to form a viscous mud. The viscous mud is filled into a columnar rod mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire blank is dried at a temperature of 50°C to form an adsorption rod with a side length of 20mm and a length of 500mm. Capillary grooves are vertically processed on the periphery of the adsorption rod, and the width and depth of the capillary grooves are 0.1mm and 0.1mm, and the distance between two adjacent capillary grooves is 1mm.

[0042] S202: Preparation of adsorption plate After the peat and diatomaceous earth with larger particles are crushed to a particle size of 5mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:3, and water is added to form a viscous mud. The viscous mud is filled into a plate-shaped mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire blank is dried at a temperature of 50°C to form an adsorption plate with a thickness of 3cm, a width of 40cm, and a length of 60cm. 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.

[0043] S203: Preparation of catalyst Ferrous sulfate is prepared into a 10% solution to form a catalyst.

[0044] S204: adding ammonium persulfate to the contaminated soil, turning the soil, and mixing, wherein the mass ratio of the pollutants to the persulfate in the contaminated soil is 10:1.

[0045] S205: Insert the adsorption rod vertically into the contaminated soil, and the depth of the adsorption rod inserted into the contaminated soil is 2 / 3 of the height of the adsorption rod. An adsorption plate is movably connected to the top of the six adsorption rods, and 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 effect of the soil itself and the capillary siphon effect of the adsorption rod, the ammonium persulfate in the contaminated soil is adsorbed into the adsorption rod, and then collected into the adsorption plate from bottom to top.

[0046] S206: Pour a catalyst onto the adsorption plate every 3 days, and the ammonium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing effect of the catalyst.

[0047] S207: The adsorption plate is placed facing the sunlight. When the crystallized area of ​​ammonium persulfate on the adsorption plate is larger than half of the area of ​​the adsorption plate, the adsorption plate is washed with water to allow the crystallized ammonium persulfate to return to the contaminated soil.

[0048] Example 3 The present invention provides a method for remediating contaminated soil, the method comprising: S301: Preparation of adsorption rods After the peat and diatomaceous earth with larger particles are crushed to a particle size of 6mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:3, and water is added to form a viscous mud. The viscous mud is filled into a columnar rod mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire blank is dried at a temperature of 55°C to form an adsorption rod with a side length of 15mm and a length of 400mm. Capillary grooves are vertically processed on the periphery of the adsorption rod, and the width and depth of the capillary grooves are 1mm; the distance between two adjacent capillary grooves is 1.5mm.

[0049] S302: Preparation of adsorption plate After the peat and diatomaceous earth with larger particles are crushed to a particle size of 6 mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:3, and water is added to form a viscous mud. The viscous mud is filled into a plate-shaped mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire 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 an adsorption rod can be clamped in each card slot.

[0050] S303: Preparation of catalyst Ferrous sulfate is prepared into a 12% solution to form a catalyst.

[0051] S304: adding potassium persulfate to the contaminated soil, turning the soil and mixing it evenly, wherein the mass ratio of the pollutants to the persulfate in the contaminated soil is 10:3.

[0052] S305: Insert the adsorption rod vertically 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 connected to the top of the six adsorption rods, and 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 effect of the soil itself and the capillary siphon effect of the adsorption rod, potassium persulfate in the contaminated soil is adsorbed into the adsorption rod, and then collected into the adsorption plate from bottom to top.

[0053] S306: Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing effect of the catalyst.

[0054] S307: The adsorption plate is placed facing the sunlight. When the crystallized area of ​​potassium persulfate on the adsorption plate is larger than half of the area of ​​the adsorption plate, the adsorption plate is washed with water to return the crystallized potassium persulfate to the contaminated soil.

[0055] Example 4 The present invention provides a method for remediating contaminated soil, the method comprising: S401: Preparation of adsorption rods After the peat and diatomaceous earth with larger particles are crushed to a particle size of 6mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:3, and water is added to form a viscous mud. The viscous mud is filled into a columnar rod mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire blank is dried at a temperature of 55°C to form an adsorption rod with a diameter of 15mm and a length of 400mm. Capillary grooves are vertically processed on the periphery of the adsorption rod, and the width and depth of the capillary grooves are 1mm and 1mm, respectively; the distance between two adjacent capillary grooves is 1.5mm.

[0056] S402: Preparation of adsorption plate After the peat and diatomaceous earth with larger particles are crushed to a particle size of 6 mm, the peat and diatomaceous earth are mixed evenly in a mass ratio of 7:3, and water is added to form a viscous mud. The viscous mud is filled into a plate-shaped mold, filled or compacted, and the viscous mud is demolded after being shaped to form a tire blank. The tire 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, a cotton thread is set between two adjacent card slots so that the catalyst flows along the cotton thread into the contaminated soil.

[0057] S403: Preparation of catalyst Ferrous sulfate is prepared into a 12% solution to form a catalyst.

[0058] S404: adding potassium persulfate to the contaminated soil, turning the soil and mixing it evenly, wherein the mass ratio of the pollutants to the persulfate in the contaminated soil is 10:3.

[0059] S405: Insert the adsorption rod vertically 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 connected to the top of the N adsorption rods, and 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 effect of the soil itself and the capillary siphon effect of the adsorption rod, the potassium persulfate in the contaminated soil is adsorbed into the adsorption rod, and then collected into the adsorption plate from bottom to top.

[0060] S406: Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing effect of the catalyst.

[0061] S407: The adsorption plate is placed facing the sunlight. When the crystallized area of ​​potassium persulfate on the adsorption plate is larger than half of the area of ​​the adsorption plate, the adsorption plate is washed with water to return the crystallized potassium persulfate to the contaminated soil.

[0062] Example 5 The present invention provides a method for remediating contaminated soil, the method comprising: S501: Preparation of adsorption rods Peat was calcined at 380°C for 2h to obtain calcined peat. Diatomaceous earth was calcined at 900°C for 2h to obtain calcined diatomaceous earth. After the calcined peat and calcined diatomaceous earth were crushed to a particle size of 6mm, the calcined peat and calcined diatomaceous earth were evenly mixed in a mass ratio of 7:3, and water was added to form a viscous mud. The viscous mud was filled into a columnar rod mold, filled or compacted, and the viscous mud was demolded after being shaped to form a tire blank. The tire blank was dried at a temperature of 55°C to form an adsorption rod with a side length of 15mm and a length of 400mm. Capillary grooves were vertically processed on the periphery of the adsorption rod, and the width and depth of the capillary grooves were 1mm and 1mm, and the distance between two adjacent capillary grooves was 1.5mm.

[0063] S502: Preparation of adsorption plate Peat soil was calcined at 380°C for 2h to obtain calcined peat soil. Diatomaceous earth was calcined at 900°C for 2h to obtain calcined diatomaceous earth. After the calcined peat soil and calcined diatomaceous earth were crushed to a particle size of 6mm, the calcined peat soil and calcined diatomaceous earth were evenly mixed in a mass ratio of 7:3, and water was added to form a viscous mud. The viscous mud was filled into a plate-shaped mold, filled or compacted, and the viscous mud was demolded after being shaped to form a tire blank. The tire blank was dried at a temperature of 55°C to form an adsorption plate with a thickness of 4cm, a width of 40cm, and a length of 60cm. Six card slots were processed on the bottom surface of the adsorption plate so that an adsorption rod could be clamped in each card slot. At the same time, a cotton thread was set between two adjacent card slots so that the catalyst could flow along the cotton thread into the contaminated soil.

[0064] S503: Preparation of catalyst Ferrous sulfate is prepared into a 12% solution to form a catalyst.

[0065] S504: adding potassium persulfate to the contaminated soil, turning the soil and mixing it evenly, wherein the mass ratio of the pollutants to the persulfate in the contaminated soil is 10:3.

[0066] S505: Insert the adsorption rod vertically 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 connected to the top of the six adsorption rods, and 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 effect of the soil itself and the capillary siphon effect of the adsorption rod, potassium persulfate in the contaminated soil is adsorbed into the adsorption rod, and then collected into the adsorption plate from bottom to top.

[0067] S506: Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing effect of the catalyst.

[0068] S507: The adsorption plate is placed facing the sunlight. When the crystallized area of ​​potassium persulfate on the adsorption plate is larger than half of the area of ​​the adsorption plate, the adsorption plate is washed with water to return the crystallized potassium persulfate to the contaminated soil.

[0069] Example 6 The present invention provides a method for remediating contaminated soil, the method comprising: S601: Preparation of adsorption rods Peat was calcined at 300°C for 5 hours to obtain calcined peat. Diatomaceous earth was calcined at 750°C for 5 hours to obtain calcined diatomaceous earth. After the calcined peat and calcined diatomaceous earth were crushed to a particle size of 6 mm, the calcined peat and calcined diatomaceous earth were evenly mixed in a mass ratio of 7:3, and water was added to form a viscous mud. The viscous mud was filled into a columnar rod mold, filled or compacted, and the viscous mud was demolded after being shaped to form a tire blank. The tire blank was 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. Capillary grooves were vertically processed on the periphery of the adsorption rod, and the width and depth of the capillary grooves were 1 mm and 1 mm, and the distance between two adjacent capillary grooves was 1.5 mm.

[0070] S602: Preparation of adsorption plate Peat soil was calcined at 300°C for 5 hours to obtain calcined peat soil. Diatomaceous earth was calcined at 750°C for 5 hours to obtain calcined diatomaceous earth. After the calcined peat soil and calcined diatomaceous earth were crushed to a particle size of 6 mm, the calcined peat soil and calcined diatomaceous earth were mixed evenly in a mass ratio of 7:3, and water was added to form a viscous mud. The viscous mud was filled into a plate-shaped mold, filled or compacted, and the viscous mud was demolded after being shaped to form a tire blank. The tire blank was 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 were processed on the bottom surface of the adsorption plate so that an adsorption rod could be clamped in each card slot. At the same time, a cotton thread was set between two adjacent card slots so that the catalyst could flow along the cotton thread into the contaminated soil.

[0071] S603: Preparation of catalyst Ferrous sulfate is prepared into a 12% solution to form a catalyst.

[0072] S604: adding potassium persulfate to the contaminated soil, turning the soil and mixing it evenly, wherein the mass ratio of the pollutants to the persulfate in the contaminated soil is 10:3.

[0073] S605: Insert the adsorption rod vertically 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 connected to the top of the six adsorption rods, and 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 effect of the soil itself and the capillary siphon effect of the adsorption rod, potassium persulfate in the contaminated soil is adsorbed into the adsorption rod, and then collected into the adsorption plate from bottom to top.

[0074] S606: Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing effect of the catalyst.

[0075] S607: The adsorption plate is placed facing the sunlight. When the crystallized area of ​​potassium persulfate on the adsorption plate is larger than half of the area of ​​the adsorption plate, the adsorption plate is washed with water to return the crystallized potassium persulfate to the contaminated soil.

[0076] Example 7 The present invention provides a method for remediating contaminated soil, the method comprising: S701: Preparation of adsorption rods Peat was calcined at 350°C for 3 hours to obtain calcined peat. Diatomaceous earth was calcined at 800°C for 3 hours to obtain calcined diatomaceous earth. After the calcined peat and calcined diatomaceous earth were crushed to a particle size of 6 mm, the calcined peat and calcined diatomaceous earth were evenly mixed in a mass ratio of 7:3, and water was added to form a viscous mud. The viscous mud was filled into a columnar rod mold, filled or compacted, and the viscous mud was demolded after being shaped to form a tire blank. The tire blank was 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. Capillary grooves were vertically processed on the periphery of the adsorption rod, and the width and depth of the capillary grooves were 1 mm and 1 mm, and the distance between two adjacent capillary grooves was 1.5 mm.

[0077] S702: Preparation of adsorption plate Peat soil was calcined at 350°C for 3 hours to obtain calcined peat soil. Diatomaceous earth was calcined at 800°C for 3 hours to obtain calcined diatomaceous earth. After the calcined peat soil and calcined diatomaceous earth were crushed to a particle size of 6 mm, the calcined peat soil and calcined diatomaceous earth were mixed evenly in a mass ratio of 7:3, and water was added to form a viscous mud. The viscous mud was filled into a plate-shaped mold, filled or compacted, and the viscous mud was demolded after being shaped to form a tire blank. The tire blank was 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 were processed on the bottom surface of the adsorption plate so that an adsorption rod could be clamped in each card slot. At the same time, a cotton thread was set between two adjacent card slots so that the catalyst could flow along the cotton thread into the contaminated soil.

[0078] S703: Catalyst preparation Ferrous sulfate is prepared into a 12% solution to form a catalyst.

[0079] S704: adding potassium persulfate to the contaminated soil, turning the soil and mixing, wherein the mass ratio of pollutants to persulfate in the contaminated soil is 10:3.

[0080] S705: Insert the adsorption rod vertically 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 connected to the top of the six adsorption rods, and 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 effect of the soil itself and the capillary siphon effect of the adsorption rod, the potassium persulfate in the contaminated soil is adsorbed into the adsorption rod, and then collected into the adsorption plate from bottom to top.

[0081] S706: Pour the catalyst onto the adsorption plate every 5 days, and the potassium persulfate collected on the adsorption plate re-enters the contaminated soil under the flushing effect of the catalyst.

[0082] S707: The adsorption plate is placed facing the sunlight. When the crystallized area of ​​potassium persulfate on the adsorption plate is larger than half of the area of ​​the adsorption plate, the adsorption plate is rinsed with water to allow the crystallized potassium persulfate to return to the contaminated soil.

[0083] The methods shown in Examples 3, 4, and 7 were applied to the same contaminated soil. Before the adsorption rod was inserted into the contaminated soil, the contents of Cd, Pb, As, and Cr in the soil were detected at a depth of 5 cm, 10 cm, 20 cm, 30 cm, and 40 cm along the vertical direction of the soil. The test results are shown in Table 1. After the methods shown in Examples 3, 4, and 7 were applied to the above contaminated soil for one and a half years, the contents of heavy metals at different vertical depths of the soil were detected, as shown in Table 2.

[0084] Table 1: Heavy metal content in contaminated soil at different depths (mg / kg) Table 2: Heavy metal content in contaminated soil treated by methods of Examples 3, 4, and 7 (mg / kg) According to the contents in Tables 1 and 2, after the contaminated soil was repaired using the repair methods of Examples 3, 4, and 7, the content of each heavy metal in the soil was greatly reduced.

[0085] By comparing the remediation methods of Examples 3 and 4, it can be seen that compared with the setting in Example 3 in which no cotton thread was added to the adsorption plate, after adding cotton thread to the adsorption plate in Example 4, the content of various heavy metals in the soil was lower, which shows that catalyst flushing and water flushing can greatly improve the migration efficiency of persulfate and increase the soil remediation rate.

[0086] By comparing the repair methods of Examples 4 and 7, it can be seen that compared with the adsorption rods and adsorption plates prepared by using untreated peat soil and diatomaceous earth in Example 4, the content of various heavy metals in the soil was greatly reduced after using high-temperature calcined peat soil and diatomaceous earth in Example 7. This shows that the adsorption rods and adsorption plates prepared by high-temperature calcined peat soil and diatomaceous earth have higher adsorption capacity and water absorption, further improve the migration efficiency of persulfate, and improve the soil repair rate.

[0087] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. 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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