CN109877146B - Arsenic-polluted soil restoration structure and restoration method - Google Patents
Arsenic-polluted soil restoration structure and restoration method Download PDFInfo
- Publication number
- CN109877146B CN109877146B CN201910181401.4A CN201910181401A CN109877146B CN 109877146 B CN109877146 B CN 109877146B CN 201910181401 A CN201910181401 A CN 201910181401A CN 109877146 B CN109877146 B CN 109877146B
- Authority
- CN
- China
- Prior art keywords
- soil
- arsenic
- layer
- repairing
- leaching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses an arsenic-polluted soil restoration structure and a restoration method, wherein the arsenic-polluted soil restoration structure comprises a separation wall, and the separation wall surrounds to form an isolation area; a first repairing layer, an isolating hydrophobic layer, an adsorption layer and a second repairing layer are sequentially arranged in the isolation region from bottom to top, wherein the first repairing layer is made of stabilized soil obtained by repairing soil with the total arsenic content of more than 500mg/kg and the arsenic leaching toxicity of more than 0.5mg/L and heavily polluted by arsenic; the second repairing layer is made of soil obtained by leaching and repairing moderate and light arsenic-polluted soil with the total arsenic content of less than 500mg/kg, and/or soil obtained by leaching, repairing and modifying the moderate and light arsenic-polluted soil; the modification treatment includes arsenic stabilization treatment and/or soil pH adjustment treatment. Through the mode, the arsenic-polluted soil restoration structure disclosed by the invention can greatly shorten the restoration period of the arsenic-polluted soil, and is good in restoration effect, strong in durability and stability and low in restoration cost.
Description
Technical Field
The invention relates to the technical field of soil remediation, in particular to a remediation structure and a remediation method for arsenic-contaminated soil.
Background
Arsenic is classified as a known carcinogen by the World Health Organization (WHO) and the united states Environmental Protection Agency (EPA), and long-term exposure of the human body to arsenic can lead to skin cancer and canceration of internal organs such as the kidney, liver, bladder, etc. Arsenic pollution of soil has become one of the environmental pollution problems of general concern.
For arsenic-contaminated soil remediation, currently, the commonly used methods are solidification/stabilization remediation, chemical leaching remediation or phytoremediation. The curing/stabilizing repair cost is low, but only the arsenic leaching toxicity can be reduced, but the total arsenic content cannot be reduced, and the arsenic leaching toxicity of the soil can be reversely increased under the condition change, so that the repair effect is unstable; the chemical leaching repair period is short, the total amount of arsenic can be reduced, and the repair is thorough, but the repair cost is higher than that of a solidification/stabilization technology, and the leaching waste liquid treatment problem exists; the phytoremediation has the advantages of low cost and landscape effect, but the remediation period is long, the remediation period of heavily polluted soil is hundreds of years, and the requirement of rapid development of urbanization cannot be met.
The conventional arsenic-polluted soil remediation methods cannot meet the requirements of remediation period, remediation cost and remediation durability on the basis of standard remediation. Therefore, with the national attention on soil pollution and the pace of rapid development of urbanization, a remediation scheme for arsenic-polluted soil with short remediation period, low remediation cost, good remediation effect and strong durability is urgently needed.
Disclosure of Invention
In order to solve the technical problems, the invention provides a structure and a method for repairing arsenic-polluted soil.
The technical scheme adopted by the invention is as follows: an arsenic-contaminated soil remediation structure comprising: the barrier walls surround to form an isolation region; a first repairing layer, a separation hydrophobic layer, an adsorption layer and a second repairing layer are sequentially arranged in the isolation region from bottom to top; the first repairing layer is made of soil obtained by stabilizing and repairing soil polluted by severe arsenic, and the soil polluted by severe arsenic is soil with a total arsenic content of more than 500mg/kg and arsenic leaching toxicity of more than 0.5 mg/L; the second repairing layer is made of soil obtained by leaching and repairing moderate and light arsenic-polluted soil and/or soil obtained by leaching, repairing and modifying the moderate and light arsenic-polluted soil; the medium and light arsenic-polluted soil is soil with the total arsenic content of less than 500 mg/kg; the modification treatment comprises arsenic stabilization treatment and/or soil pH adjustment treatment.
Preferably, the thickness of the isolation hydrophobic layer is 15-20 cm; the thickness of the adsorption layer is 20-40 cm; the thickness of the second repairing layer is 1.0-1.5 m.
Preferably, the second repairing layer is also provided with an improved layer, and a repairing plant is planted on the improved layer; the material of the improvement layer is soil obtained by leaching, repairing, modifying and improving medium and light arsenic-polluted soil. The thickness of the modified layer is generally 15-20cm, and the repair plants are preferably evergreen plants. Through setting up the improvement layer and planting the plant on the improvement layer to further carry out phytoremediation, with low costs, and can obtain the landscape effect.
Preferably, the arsenic leaching toxicity of the soil obtained by stabilizing and repairing the heavy arsenic contaminated soil meets the comprehensive wastewater discharge standard (GB 8978-; the total arsenic content of the soil obtained by leaching and repairing the medium and light arsenic-polluted soil meets the greening planting soil standard (CJ/T340-2016), namely is less than or equal to 55 mg/kg; the pH value of the soil obtained by leaching, repairing and modifying the medium and light arsenic-polluted soil meets the greening planting soil standard (CJ/T340-2016), and the arsenic leaching toxicity meets the comprehensive sewage discharge standard (GB 8978-1996).
The invention also provides a method for restoring the arsenic-polluted soil, which comprises the following steps:
s1, arranging a landfill groove at the landfill position of the arsenic-polluted soil, arranging a barrier wall on the inner side wall of the landfill groove, and enclosing the barrier wall to form an isolation region; dividing the arsenic-polluted soil into severe arsenic-polluted soil and moderate and mild arsenic-polluted soil, wherein the severe arsenic-polluted soil is soil with a total arsenic content of more than 500mg/kg and arsenic leaching toxicity of more than 0.5 mg/L; the medium and light arsenic-polluted soil is soil with the total arsenic content of less than 500 mg/kg;
s2, adding an arsenic stabilizer into the soil with severe arsenic pollution for stabilization and restoration, and then burying the soil in the isolation region to form a first restoration layer;
s3, arranging an isolation hydrophobic layer on the first repairing layer; arranging an adsorption layer on the isolation hydrophobic layer;
and S4, adding an eluting agent into the medium and light arsenic-polluted soil for eluting and repairing, and then burying the eluting agent on the adsorption layer to form a second repairing layer.
Preferably, the method for remediating arsenic-contaminated soil may further include: adding organic fertilizer into the surface soil of the second repairing layer for improvement to form an improved layer, and planting repairing plants on the improved layer; the organic fertilizer can be dead branch and fallen leaf compost or mushroom residue fertilizer, the addition amount of the organic fertilizer is preferably 15% -30% of the soil volume of the improved layer, and the surface soil thickness of the improved second repairing layer is generally 15-20 cm. The surface soil of the second repairing layer is repaired by adopting the organic fertilizer, so that the fertility of the soil is increased, and the growth of the repairing plants is facilitated. The preferable choice of the restoration plants is evergreen plants, which can avoid the arsenic absorbed by the plants from reentering the soil along with fallen leaves to cause secondary pollution.
In step S1, a soil water barrier (generally, a soil layer or a rock layer that is impermeable to gravity flow) is provided at the bottom of a landfill groove provided at the arsenic-contaminated soil landfill site; the separation wall is arranged on the inner side wall of the landfill groove, extends downwards to the soil water-resisting layer and extends upwards to be higher than the surface of the soil, the separation wall encloses a separation area, and the separation area is separated from the periphery so that when the inside of the landfill groove is filled with the polluted soil, the landfill polluted soil is separated from the surrounding soil. The material of the barrier wall can be reinforced concrete material, and the thickness range of the barrier wall is generally 10-30 cm.
In step S2, the soil with serious arsenic pollution is generally stabilized and repaired until the arsenic leaching toxicity of the soil meets the comprehensive wastewater discharge standard (GB 2-. Specifically, the arsenic stabilizer can be added into soil, the mixture is uniformly stirred with the soil, water is added to keep the water content of the soil to be about 35%, the mixture is uniformly stirred and maintained for 7-14 days, a sample is taken, the arsenic leaching toxicity of the soil is measured, and if the arsenic leaching toxicity of the soil is greater than the limit value (0.5mg/L) of the comprehensive sewage discharge standard (GB 8978-. And burying the soil after the stabilized restoration reaches the standard to the isolation area, and compacting to form a first restoration layer. The arsenic stabilizer used in the stabilizing and repairing process can be ferrous sulfate, and the addition amount of the ferrous sulfate is generally 0.5-2.5% of the mass ratio of the ferrous sulfate to the heavy arsenic-polluted soil.
In step S3, an adsorption layer is preferably formed by spreading and filling an adsorbent on the hydrophobic isolation layer, where the adsorbent is a mixture of iron powder and quartz sand; the volume ratio of the iron powder to the quartz sand is preferably 1 (80-120). The material for isolating the hydrophobic layer can be pebbles, and preferably pebbles with the particle size of 0.5-3 cm are adopted.
In step S4, an eluting agent is generally added to the medium-and-light arsenic-contaminated soil to perform elution remediation until the total arsenic content of the soil reaches the standard, and specifically, the eluting agent may be added according to a solid-to-liquid ratio of 1g: (5-15) mL of the leaching solution is added into the polluted soil, leaching is carried out for 2-3 h, solid-liquid separation is carried out, the leaching solution is collected to measure the arsenic concentration, the arsenic removal rate is calculated, the total arsenic content remained in the soil is preliminarily calculated from the removal rate, if the total arsenic content of the soil is larger than the limit value of a greening planting soil standard (CJ/T340 + 2016), leaching is continued until the calculated total arsenic content of the soil is lower than the limit value of the greening planting soil standard (CJ/T340 + 2016), leaching waste liquid is collected, and the leaching waste liquid is added into the soil according to the solid-liquid ratio of 1g: (5-15) adding clean water into the obtained product mL, continuously leaching for 20-40 min, and carrying out solid-liquid separation to obtain the soil with the total arsenic reaching the standard after leaching.
The eluent can be water, oxalic acid, mixed solution of oxalic acid and thiourea, oxalic acid and H2O2The mixed solution of oxalic acid and thiourea; more preferably, the mass concentration of the oxalic acid in the eluting agent is 0.9-3.6%, and the mass concentration of the thiourea is 0.5-1.5%. Adopts the mixed solution of oxalic acid and thiourea asThe leaching agent can reduce As (V) in soil to As (III) by utilizing thiourea, and the dissolving capacity of As (III) is higher than that of As (V), thereby greatly improving the leaching efficiency.
Preferably, in step S4, the waste liquid generated in the rinsing process is collected during the rinsing repair process, and is purified and recycled. The waste liquid purification and recycling process specifically comprises the following steps: first adopts H2O2Oxidizing As (III) in the waste liquid into As (V), adding ferrous sulfate, lime powder and activated carbon for treatment, extracting the supernatant after the heavy metal concentration and pH of the supernatant after the leaching waste liquid treatment meet IV-class water standards of surface water, wherein the supernatant can be used for preparing a leaching agent and can also be used for leaching polluted soil, so that the leaching waste liquid is recycled. And (4) sending the precipitate generated in the leaching waste liquid treatment process into a hazardous waste landfill for safe disposal.
In step S4, after adding an eluting agent to the medium and light arsenic-contaminated soil for leaching remediation, preferably, modifying the remediated soil, wherein the modifying includes arsenic stabilization and/or soil pH adjustment; preferably, arsenic stabilization treatment and soil pH adjustment treatment are adopted, and specifically, the method comprises the steps of adding an oxidant into the washed and repaired soil, mixing, adding an arsenic stabilizer and an alkaline pH regulator, mixing, adding water to keep the water content of the soil to be about 35% usually, and maintaining for 7-14 days. Through the modification treatment, the arsenic stabilization treatment utilizes an oxidant to oxidize As (III) remained in the soil after the leaching restoration reaches the standard into As (V), and then an arsenic stabilizer is added to stabilize the As (V), so that the leaching toxicity is reduced, and the stability of the restoration effect is improved; the pH value of the soil is improved by adding an alkaline pH regulator in the soil pH adjustment treatment, so that the pH value of the modified soil meets the environmental requirements required by plant growth. Therefore, the modification treatment can be carried out until the pH of the soil meets the greening planting soil standard (CJ/T340-.
Preferably, the oxidant is H2O2，H2O2The addition amount of the compound is 0.5 to 1.5 percent of the mass ratio of the compound to the soil after leaching remediation; the arsenic stabilizer is ferrous sulfate, and the addition amount of the ferrous sulfate is 0.5-1.5% of the mass ratio of the leached and repaired soil; the alkaline pH regulator is CaO, and the addition amount of the CaO is 0.3-0.7% of the mass ratio of the CaO to the soil after leaching remediation.
The corresponding arsenic-polluted soil remediation structure can be formed by the arsenic-polluted soil remediation method.
The beneficial technical effects of the invention are as follows: the invention provides an arsenic-polluted soil restoration structure and a restoration method, wherein the arsenic-polluted soil restoration structure forms an isolation region through the arrangement of a partition wall and the enclosure of the partition wall, so that secondary pollution of a restoration layer soil material in the isolation region to the surrounding environment in the later period can be avoided. Through the arrangement of the first repairing layer and the second repairing layer, the arsenic-polluted soil is divided into the heavy arsenic-polluted soil and the medium-light arsenic-polluted soil according to the pollution degree, different types of arsenic-polluted soil are reasonably repaired by different methods, wherein the heavy arsenic-polluted soil with higher arsenic content is stably repaired, the medium-light arsenic-polluted soil with relatively low arsenic content is rinsed and repaired, the rinsing waste liquid amount can be reduced, the repairing cost is reduced on the basis of ensuring the repairing effect, and the repairing period is short. In addition, the adsorption layer is arranged between the first repairing layer and the second repairing layer, so that arsenic which is migrated from the second repairing layer along with precipitation can be adsorbed by the adsorption layer; be equipped with between adsorbed layer and the first restoration layer and keep apart the hydrophobic layer, can play the isolation effect on the one hand, avoid the adsorbed layer to adsorb arsenic in the first restoration layer, on the other hand keeps apart the effect that the hydrophobic layer can play the drainage guide, and then can control the soil arsenic in the first restoration layer to a certain extent and leach the problem that the toxicity rose. In conclusion, through the arsenic-polluted soil restoration structure, the restoration period of the arsenic-polluted soil can be greatly shortened, the restoration effect is good, the durability and the stability are strong, the restoration cost is low, the structure is particularly suitable for being used in urban arsenic-polluted sites, and the urban arsenic-polluted sites can be efficiently and quickly restored.
Drawings
In order to more clearly illustrate the technical solution in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below.
FIG. 1 is a schematic structural view of a remediation structure for arsenic-contaminated soil according to example 1 of the present invention;
fig. 2 is a schematic structural diagram of a structure for repairing arsenic-contaminated soil in embodiment 2 of the present invention.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. Furthermore, it should be understood that various changes and modifications can be made by those skilled in the art after reading the teachings of the present invention, and such equivalents also fall within the scope of the appended claims.
Example 1
The method for restoring the arsenic-polluted soil comprises the following steps:
and S1, forming a landfill groove at the landfill position of the arsenic-polluted soil, and arranging a barrier wall on the inner side wall of the landfill groove, wherein the barrier wall encloses an isolation region isolated from the periphery. Specifically, the bottom of the landfill groove is located at a soil water barrier (the water barrier is generally a coating or rock stratum which cannot be penetrated by gravity flow), and the barrier wall extends downwards to the soil water barrier and upwards to be higher than the soil surface, and specifically can be higher than the soil surface by about 10 cm. The material of the separation wall is reinforced concrete material, and the thickness is about 20 cm. Through the setting of separation wall, the inside isolation region that forms of landfill recess, the inside soil isolation around with of landfill recess.
S2, dividing the arsenic-polluted soil into severe arsenic-polluted soil and medium-mild arsenic-polluted soil, wherein the severe arsenic-polluted soil is soil with a total arsenic content of more than 500mg/kg and arsenic leaching toxicity of more than 0.5 mg/L; the medium and light arsenic-polluted soil is soil with the total arsenic content less than 500 mg/kg. Taking soil with serious arsenic pollution, the total arsenic content of which is 1462mg/kg and the arsenic leaching toxicity of which is 1.12mg/L, of a certain site as first soil to be repaired, and taking soil with medium-light arsenic pollution, the total arsenic content of which is 312mg/kg, of another site as second soil to be repaired.
S3, adding an arsenic stabilizer into the first soil to be repaired (namely the soil with serious arsenic pollution obtained in the step S2) to perform stabilization repair until the arsenic leaching toxicity of the soil reaches the standard. Specifically, adding ferrous sulfate with the mass ratio of 1.5% to the soil into the first soil to be repaired, uniformly stirring, adding water to keep the water content of the soil to be about 35%, continuously and uniformly stirring, maintaining for 7 days, sampling, and measuring the arsenic leaching toxicity of the soil to be repaired to be 0.11mg/L, which is lower than the limit value (0.5mg/L) of the comprehensive sewage discharge standard (GB 8978 + 1996), wherein the arsenic leaching toxicity of the soil to be repaired reaches the standard. And then burying the restoring soil into the isolation area, and compacting to form a first restoring layer.
And S4, arranging an isolation hydrophobic layer on the first repairing layer. Specifically, pebbles with the grain diameter of 0.5-3 cm and the thickness of 15-20cm are paved and filled on the first repairing layer to form an isolation hydrophobic layer, so that the arsenic in the first repairing layer can be isolated, and meanwhile, the hydrophobic effect can be realized.
And S5, arranging an adsorption layer on the isolation hydrophobic layer. Specifically, an adsorbent formed by fully and uniformly mixing iron powder and quartz sand according to the volume ratio of 1:120 is paved and filled on the isolation hydrophobic layer, and the thickness of the adsorbent is 20-40 cm, so that an adsorption layer is formed.
And S6, adding a leaching agent into the second soil to be repaired (namely the medium-light arsenic-polluted soil obtained in the step S2) to carry out leaching and repairing treatment until the total arsenic content of the soil reaches the standard. Specifically, oxalic acid, thiourea and water are mixed to prepare an eluent, wherein the mass concentration of the oxalic acid in the eluent is 2.25%, and the mass concentration of the thiourea is 1%; and then according to the solid-liquid ratio of the second soil to be repaired to the eluting agent of 1g:10mL of leaching agent is added into the second soil to be repaired for leaching repair, leaching is carried out for 2h, solid-liquid separation is carried out, the leaching solution is collected to measure the arsenic concentration, the arsenic removal rate is calculated, the total arsenic content remained in the soil is preliminarily calculated from the removal rate to be 68.64mg/kg and is larger than the limit value (55mg/kg) of the greening planting soil standard (CJ/T340-one 2016), and the steps are carried out continuously according to the solid-liquid ratio of 1g: adding an eluting agent into 10mL of the soil, eluting for 2h, carrying out solid-liquid separation, and adding the mixture into the soil according to the solid-liquid ratio of 1g: adding clean water into 10mL of the mixed solution, continuously leaching for 30min, performing solid-liquid separation, taking a soil sample, and measuring that the total arsenic content of the leached soil is 25.89mg/kg and is lower than the limit value (55mg/kg) of the greening planting soil standard (CJ/T340-one 2016), and the total arsenic content of the soil reaches the standard.
And treating waste liquid generated in the leaching process. Specifically, H may be first employed2O2Oxidizing As (III) in the waste liquid into As (V), then adding ferrous sulfate, lime powder and active carbon for treatment, and extracting the supernatant liquid for preparing an eluting agent or for eluting the medium-light arsenic-polluted soil after the heavy metal concentration and the pH of the supernatant liquid after the eluting waste liquid treatment meet IV-class water standards of surface water, so that the eluting waste liquid can be recycled and reused. And (4) sending the precipitate generated in the leaching waste liquid treatment process into a hazardous waste landfill for safe disposal.
S7, measuring the pH value of the soil treated in the step S6, and measuring that the pH value of the soil is 3.69 and is not suitable for plant growth, so that the soil is modified to meet the requirements of plant growth environment. Specifically, 1.0% by mass of H to the soil was added to the soil2O2Uniformly mixing, then adding ferrous sulfate with the mass ratio of 1.0% to soil and CaO with the mass ratio of 0.5% to soil, uniformly mixing, then adding water to keep the water content of the soil about 35%, continuously stirring and uniformly mixing, taking samples after curing for 7 days, measuring the pH value of the soil to be 6.21, meeting the greening planting soil standard (CJ/T340-2016), and measuring the arsenic leaching toxicity to be 0.08mg/L, which is far lower than the limit value of the comprehensive sewage discharge standard (0.5 mg/L). And then burying the modified soil on the adsorption layer, wherein the thickness of the soil is 1.0-1.5 m, and forming a second repairing layer.
S8, improving the soil on the surface layer of the second repairing layer by using an organic fertilizer to form an improved layer; wherein the thickness of the surface soil subjected to improvement treatment is 15-20cm, the organic fertilizer can be dead branch and fallen leaf compost or mushroom residue fertilizer, and the addition amount of the organic fertilizer accounts for 20% of the volume of the soil.
And S9, planting the restoration plants on the improved layer, and maintaining.
The arsenic-contaminated soil remediation structure can be formed by the arsenic-contaminated soil remediation method, and comprises a separation wall 11, wherein the separation wall 11 encloses to form an isolation region, and a first remediation layer 12, an isolation hydrophobic layer 13, an adsorption layer 14, a second remediation layer 15 and an improvement layer 16 are sequentially arranged in the isolation region from bottom to top; the modified layer 16 is planted with a repair plant 17. The first repairing layer 12 is made of soil obtained by stabilizing and repairing soil polluted by severe arsenic; the second repairing layer 15 is made of soil obtained by leaching and modifying medium and light arsenic-polluted soil, and the modifying treatment is arsenic stabilizing treatment and soil pH adjusting treatment.
Example 2
The method for restoring the arsenic-polluted soil comprises the following steps:
s1, a landfill groove is formed in the landfill position of the arsenic-polluted soil, the bottom of the landfill groove is located on a soil water-resisting layer, a reinforced concrete material is adopted to arrange a separation wall on the inner side wall of the landfill groove, the separation wall extends downwards to the soil water-resisting layer and upwards to be 15cm higher than the surface of the soil, the thickness of the separation wall is about 15cm, and the separation wall encloses an isolation area isolated from the periphery.
S2, dividing the arsenic-polluted soil into severe arsenic-polluted soil and medium-mild arsenic-polluted soil, wherein the severe arsenic-polluted soil is soil with a total arsenic content of more than 500mg/kg and arsenic leaching toxicity of more than 0.5 mg/L; the medium and light arsenic-polluted soil is soil with the total arsenic content less than 500 mg/kg. Taking the soil with serious arsenic pollution, the total arsenic content of which in one place is 1285mg/kg and the arsenic leaching toxicity is 1.08mg/L, as the soil to be restored, and taking the soil with medium and light arsenic pollution, the total arsenic content of which in the other place is 212mg/kg, as the soil to be restored.
S3, adding ferrous sulfate with the mass ratio of 1.0% to the soil into the first soil to be repaired, stirring and mixing uniformly, adding water to keep the water content of the soil to be 35% or so, continuing stirring and mixing uniformly, maintaining for 7 days, sampling, and measuring that the arsenic leaching toxicity of the soil is 0.25mg/L and is lower than the limit value (0.5mg/L) of the comprehensive sewage discharge standard (GB 3 + 1996), wherein the arsenic leaching toxicity of the repaired soil reaches the standard. And then burying the repair soil into the isolation area, and compacting to form a first repair layer.
And S4, paving pebbles with the grain diameter of 0.5-3 cm and the thickness of 15-20cm on the first repairing layer to form a separation hydrophobic layer.
S5, an adsorbent formed by fully and uniformly mixing iron powder and quartz sand according to the volume ratio of 1:80 is paved and filled on the isolation hydrophobic layer, and the thickness is 20-40 cm, so that an adsorption layer is formed.
S6, mixing oxalic acid and water to prepare an eluent, wherein the mass concentration of the oxalic acid in the eluent is 2.0%; and then according to the solid-liquid ratio of the second soil to be repaired to the eluting agent of 1g: adding a leaching agent into the soil to be repaired for 15mL to perform leaching repair, wherein the leaching time is 2h each time, performing solid-liquid separation after each leaching, leaching for 3 times by using the leaching agent, and adding the leaching agent into the soil according to the solid-liquid ratio of 1g: adding clean water into 15mL of the mixed solution, continuously leaching for 30min, performing solid-liquid separation, collecting waste liquid generated in the leaching process, and taking a soil sample to measure that the total arsenic content of the leached soil is 38.78mg/kg and is lower than the limit value (55mg/kg) of the greening planting soil standard (CJ/T340-one 2016), and the total arsenic content of the soil reaches the standard. The effluent from the leaching process was treated in a similar manner as in example 1.
The arsenic-contaminated soil remediation structure can be formed by the arsenic-contaminated soil remediation method, and as shown in fig. 2, the arsenic-contaminated soil remediation structure comprises a partition wall 21, the partition wall 21 encloses to form an isolation region, and a first remediation layer 22, an isolation hydrophobic layer 23, an adsorption layer 24 and a second remediation layer 25 are sequentially arranged in the isolation region from bottom to top. The first repairing layer 22 is made of soil obtained by stabilizing and repairing soil polluted by severe arsenic; the second repairing layer 25 is made of soil obtained by leaching and repairing moderate and light arsenic-polluted soil.
Example 3
The method comprises the step of adopting medium and light arsenic-polluted soil (the total arsenic content is less than 500mg/kg) in a certain place in Yunnan province as soil to be repaired, wherein the total arsenic content in the soil to be repaired is 206 mg/kg. Leaching and repairing soil to be repaired by respectively adopting 4 leaching agents, namely oxalic acid, oxalic acid + thiourea (namely mixed solution of the oxalic acid and the thiourea), oxalic acid + hydroxylamine hydrochloride (namely mixed solution of the oxalic acid and the hydroxylamine hydrochloride), oxalic acid + H2O2(i.e., oxalic acid and H)2O2The mixed solution) of (1.8% by mass of oxalic acid, thiourea, hydroxylamine hydrochloride, and H2O2All concentrations of (A) were 0.75%. The specific leaching repairing method comprises the following steps: placing 10g of soil sample into a 250mL plastic bottle container, and mixing the soil sample with the eluentAdding eluting agent with solid-liquid ratio of 1g:10mL, oscillating at 200r/min for 2h, standing, separating solid and liquid, measuring the As concentration of the supernatant, and calculating the arsenic removal rate. The 4 kinds of eluting agents are respectively adopted to carry out eluting remediation on the soil to be remediated according to the method, the arsenic removal rate of the soil after eluting remediation is measured and calculated, and the obtained results are shown in table 1.
TABLE 1 arsenic removal Rate Using different leachants
As can be seen from Table 1, thiourea is added to oxalic acid, which can greatly improve the leaching efficiency, and after the oscillating leaching repair treatment, the arsenic removal rate (79.62%) of the treatment using the mixed solution of oxalic acid and thiourea as the leaching agent is significantly higher than that of the treatment using oxalic acid solution, and also significantly higher than that of the treatment using the mixed solution of oxalic acid and hydroxylamine hydrochloride, and the mixed solution of oxalic acid and H2O2The mixed solution treatment of (2) is mainly because thiourea can reduce As (V) in soil into As (III), and the dissolving capacity of As (III) is greater than that of As (V), thereby greatly improving the leaching efficiency.
Example 4
The method comprises the step of adopting medium and light arsenic-polluted soil (the total arsenic content is less than 500mg/kg) at one place in Yunnan province as soil to be repaired, wherein the total arsenic content in the soil to be repaired is 438 mg/kg. A mixed solution of oxalic acid and thiourea is used as an eluting agent, and the mass concentration of the oxalic acid in the eluting agent is 2.7%, and the mass concentration of the thiourea is 1%. Weighing 55g of soil sample into a 1000mL plastic bottle, weighing 6 parts together, adding 550mL of mixed solution of oxalic acid and thiourea into the plastic bottle according to the solid-to-liquid ratio of 1g to 10mL, oscillating for 3h at 200r/min, standing, performing solid-liquid separation, measuring the concentration of As in the supernatant, calculating the removal rate of As, preliminarily calculating the content of arsenic remained in the soil according to the removal rate, continuing oscillating and leaching when the content of arsenic is greater than the standard limit value (55mg/kg) of the planting soil, namely adding the mixed solution of oxalic acid and thiourea into the soil in the plastic bottle after the solid-liquid separation according to the solid-to-liquid ratio of 1g to 10mL, continuing oscillating for 3h, standing and performing solid-liquid separation until the total arsenic content of the leached soil is less than the standard limit value (55mg/kg) of the planting. In the embodiment, the mixed solution of oxalic acid and thiourea is adopted for leaching for 2 times, deionized water is added into the soil in the plastic bottle after solid-liquid separation according to the solid-liquid ratio of 1g:10ml, oscillation is carried out for 30min at 200r/min, standing is carried out, and solid-liquid separation is carried out; taking out the drenched and repaired soil, and measuring that the total arsenic content of the soil is 33.92mg/kg, and the total arsenic content of the soil meets the standard of greening planting soil; the soil pH was found to be 3.51, which is not suitable for plant growth. Therefore, the soil with the total arsenic content reaching the standard after washing needs to be modified, so that the pH value of the soil meets the plant growth requirement.
And (3) air-drying the soil which is taken out and washed to reach the total arsenic content standard, grinding, sieving by a 2mm sieve, and taking the sieved soil as the soil to be modified. And adding a modifying material into the soil to be modified, and performing a modification test. The specific method comprises the following steps: weighing 25g of soil to be modified in 100ml of beakers, wherein the total number of the beakers is 9, adding CaO accounting for 0.5 percent of the mass ratio of the CaO to the soil into 3 beakers, and adding ferrous sulfate and CaO accounting for FeSO accounting for 1.0 percent and 0.5 percent of the mass ratio of the ferrous sulfate and the CaO to the soil into the other 3 beakers respectively4+ CaO, adding H to the remaining 3 beakers in a mass ratio of 1.0% to the soil2O2After stirring and mixing evenly, ferrous sulfate and CaO are added according to the mass ratio of 1.0 percent and 0.5 percent respectively to the soil, and are marked as H2O2+FeSO4And (3) CaO, uniformly stirring and mixing the modified materials in all beakers with the soil, adding deionized water to keep the water content about 35%, continuously stirring and uniformly mixing, maintaining for 7 days, then sampling, and measuring the pH value of the soil and the arsenic leaching toxicity. The 9 samples are divided into 3 groups, each group is provided with 3 parallels, and each group adopts CaO and FeSO4+ CaO and H2O2+FeSO4And the CaO is used as a modification material to modify the soil to be modified, the pH value and arsenic leaching toxicity of the soil after modification treatment of each group of parallel sample soil are measured, the average value is used as the pH value and arsenic leaching toxicity of the modified soil, and the obtained result is shown in Table 2.
TABLE 2 soil pH and arsenic leach toxicity after modification with different modifying materials
As can be seen from Table 2, although the above modification treatment, which uses CaO alone or a mixed modification material of CaO and ferrous sulfate, can increase the pH of the soil, the arsenic leaching toxicity of the soil is out of the limits and does not meet the comprehensive discharge standard of sewage (0.5mg/L), but H is added first2O2Then adding ferrous sulfate and CaO for modification treatment (namely H)2O2+FeSO4And + CaO treatment), the soil pH value measured after 7 days of maintenance is 6.15, the soil meets the greening planting soil standard (CJ/T340-2016), the soil arsenic leaching toxicity is only 0.09mg/L and is far lower than the comprehensive sewage discharge standard limit value (0.5mg/L), and the soil treated by CaO and FeSO is adopted4+ CaO mix treatment phase, H2O2+FeSO4The arsenic leaching toxicity of the + CaO treated soil can be respectively reduced by 93.71% and 86.96%, and the arsenic leaching toxicity has obvious stabilizing effect on arsenic.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (11)
1. An arsenic-contaminated soil remediation structure, comprising:
the barrier walls surround to form an isolation region;
a first repairing layer, an isolation hydrophobic layer, an adsorption layer and a second repairing layer are sequentially arranged in the isolation region from bottom to top;
the first repairing layer is made of soil obtained by stabilizing and repairing soil polluted by heavy arsenic, and the soil polluted by the heavy arsenic is soil with a total arsenic content of more than 500mg/kg and arsenic leaching toxicity of more than 0.5 mg/L;
the second repairing layer is made of soil obtained by leaching and repairing moderate and light arsenic-polluted soil and/or soil obtained by leaching, repairing and modifying the moderate and light arsenic-polluted soil; the medium and light arsenic-polluted soil is soil with the total arsenic content of less than 500 mg/kg; the modification treatment comprises arsenic stabilization treatment and/or soil pH adjustment treatment.
2. The arsenic-contaminated soil remediation structure of claim 1, wherein the isolating hydrophobic layer is 15-20cm thick; the thickness of the adsorption layer is 20-40 cm; the thickness of the second repairing layer is 1.0-1.5 m.
3. The arsenic-contaminated soil remediation structure of claim 1 or 2, wherein the second remediation layer is further provided with an improvement layer, and remediation plants are planted on the improvement layer; the improved layer is soil obtained by leaching, repairing, modifying and improving medium and light arsenic-polluted soil.
4. The method for restoring the arsenic-polluted soil is characterized by comprising the following steps of:
s1, arranging a landfill groove at the landfill position of the arsenic-polluted soil, arranging a barrier wall on the inner side wall of the landfill groove, and enclosing the barrier wall to form an isolation region; dividing the arsenic-polluted soil into severe arsenic-polluted soil and moderate arsenic-polluted soil, wherein the severe arsenic-polluted soil is soil with a total arsenic content of more than 500mg/kg and an arsenic leaching toxicity of more than 0.5 mg/L; the medium and light arsenic-polluted soil is soil with the total arsenic content of less than 500 mg/kg;
s2, adding an arsenic stabilizer into the soil with severe arsenic pollution for stabilization and restoration, and then burying the soil in the isolation region to form a first restoration layer;
s3, arranging an isolation hydrophobic layer on the first repairing layer; arranging an adsorption layer on the isolation hydrophobic layer;
and S4, adding an eluting agent into the medium and light arsenic-polluted soil for eluting and repairing, and then burying the eluting agent on the adsorption layer to form a second repairing layer.
5. The method for remediating arsenic-contaminated soil as claimed in claim 4, further comprising: and adding organic fertilizer into the surface soil of the second repairing layer for improvement to form an improved layer, and planting repairing plants on the improved layer.
6. The method for remediating arsenic-contaminated soil as claimed in claim 4, wherein in step S3, an adsorption layer is provided by spreading an adsorbent on the hydrophobic isolation layer, wherein the adsorbent is a mixture of iron powder and quartz sand.
7. The method for remediating arsenic-contaminated soil as claimed in claim 4, wherein in step S4, the eluting agent is a mixed solution of oxalic acid and thiourea.
8. The method for remediating arsenic-contaminated soil as claimed in claim 4, wherein in step S4, the waste liquid generated in the leaching process is collected during the leaching remediation process, and the waste liquid is purified and recycled.
9. The method for remediating arsenic-contaminated soil as claimed in claim 4, wherein step S4, after adding the eluting agent to the medium-light arsenic-contaminated soil for leaching remediation, further comprises modifying the remediated soil, wherein the modifying comprises arsenic stabilization and/or soil pH adjustment.
10. The method for remediating arsenic-contaminated soil as claimed in claim 9, wherein the modification treatment specifically comprises: and adding an oxidant into the leached and repaired soil, mixing, adding an arsenic stabilizer and an alkaline pH regulator, mixing, and maintaining.
11. The method for remediating arsenic-contaminated soil as claimed in claim 10, wherein the oxidizing agent is H2O2，H2O2The addition amount of the fertilizer is 0.5 to 1.5 percent of the mass ratio of the fertilizer to the soil after leaching remediation; the arsenic stabilizer is ferrous sulfate, and the addition amount of the ferrous sulfate is 0.5-1.5% of the mass ratio of the leached and repaired soil; the alkaline pH regulator is CaO, and the addition amount of the CaO is 0.3-0.7% of the mass ratio of the CaO to the soil after leaching remediation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910181401.4A CN109877146B (en) | 2019-03-11 | 2019-03-11 | Arsenic-polluted soil restoration structure and restoration method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910181401.4A CN109877146B (en) | 2019-03-11 | 2019-03-11 | Arsenic-polluted soil restoration structure and restoration method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109877146A CN109877146A (en) | 2019-06-14 |
| CN109877146B true CN109877146B (en) | 2021-03-02 |
Family
ID=66931763
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910181401.4A Active CN109877146B (en) | 2019-03-11 | 2019-03-11 | Arsenic-polluted soil restoration structure and restoration method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109877146B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113000574A (en) * | 2019-12-20 | 2021-06-22 | 江苏和而同环境建设有限公司 | Method for restoring mine mercury polluted acid soil |
| CN112808756A (en) * | 2020-08-13 | 2021-05-18 | 深圳市豪科园林有限公司 | Soil restoration structure suitable for flowering plants and construction method |
| CN113546957B (en) * | 2021-07-19 | 2022-11-08 | 西南科技大学 | Trinity treatment structure applied to harmful arsenic slag pile and construction method thereof |
| CN113477691A (en) * | 2021-08-04 | 2021-10-08 | 天津大学 | Combined remediation method for arsenic-polluted soil |
| CN114160558B (en) * | 2021-11-16 | 2023-10-31 | 辽宁中博生态环境技术有限公司 | In-situ chemical barrier material for polluted soil and preparation and application thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004243313A (en) * | 2003-01-22 | 2004-09-02 | Mitsubishi Chemicals Corp | Soil cleaning method |
| CN104170554A (en) * | 2014-08-18 | 2014-12-03 | 陕西长大实业有限公司 | Soil improvement machine and soil improvement method |
| CN104174640A (en) * | 2014-08-14 | 2014-12-03 | 陕西长大实业有限公司 | Soil layer changing machine and soil improving method |
| CN104707863A (en) * | 2015-03-13 | 2015-06-17 | 爱土工程环境科技有限公司 | Farmland pollution remediation equipment and method |
| CN106216370A (en) * | 2016-08-04 | 2016-12-14 | 北京高能时代环境技术股份有限公司 | A kind of method for repairing heavy metal polluted soil of farmland |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6386796B1 (en) * | 2000-03-06 | 2002-05-14 | John H. Hull | Composite particles and methods for their application and implementation |
| CN102350437B (en) * | 2011-07-15 | 2012-09-05 | 沈阳环境科学研究院 | Method for carrying out stabilization obstruction on soil with slight heavy metal pollution |
| KR101375482B1 (en) * | 2013-05-24 | 2014-03-18 | 현대건설주식회사 | System and method for remediation of highly concentrated soil by continuous sequential advanced??separation and heavy metals removal process |
| CN204544963U (en) * | 2015-01-27 | 2015-08-12 | 深圳市铁汉生态环境股份有限公司 | A kind of obstruct repair structure for heavy metal pollution of soil |
| JP6385870B2 (en) * | 2015-03-24 | 2018-09-05 | アイシン高丘株式会社 | Arsenic remover |
| CN105363769A (en) * | 2015-12-17 | 2016-03-02 | 中国有色桂林矿产地质研究院有限公司 | Method for restoring cadmium-contaminated farmland soil |
| CN105598155A (en) * | 2015-12-31 | 2016-05-25 | 陕西清扬环境科技有限公司 | Remediation method for soil polluted by arsenic |
| CN105750317A (en) * | 2016-03-03 | 2016-07-13 | 侯绪华 | Restoration method for chromium-polluted soil |
| CN106734145A (en) * | 2016-12-19 | 2017-05-31 | 湖南金旅环保股份有限公司 | A kind of combined remediation method of heavy-metal contaminated soil |
-
2019
- 2019-03-11 CN CN201910181401.4A patent/CN109877146B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004243313A (en) * | 2003-01-22 | 2004-09-02 | Mitsubishi Chemicals Corp | Soil cleaning method |
| CN104174640A (en) * | 2014-08-14 | 2014-12-03 | 陕西长大实业有限公司 | Soil layer changing machine and soil improving method |
| CN104170554A (en) * | 2014-08-18 | 2014-12-03 | 陕西长大实业有限公司 | Soil improvement machine and soil improvement method |
| CN104707863A (en) * | 2015-03-13 | 2015-06-17 | 爱土工程环境科技有限公司 | Farmland pollution remediation equipment and method |
| CN106216370A (en) * | 2016-08-04 | 2016-12-14 | 北京高能时代环境技术股份有限公司 | A kind of method for repairing heavy metal polluted soil of farmland |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109877146A (en) | 2019-06-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109877146B (en) | Arsenic-polluted soil restoration structure and restoration method | |
| Lu et al. | Use of magnetic biochars for the immobilization of heavy metals in a multi-contaminated soil | |
| Li et al. | Mobility of Zn, Cd and Pb in soils as affected by poultry litter extract—I. Leaching in soil columns | |
| CN104259192B (en) | A kind of Ecological waterscape repair system of heavy metal pollution agricultural land soil and method | |
| Lasheen et al. | Assessment of metals speciation in sewage sludge and stabilized sludge from different Wastewater Treatment Plants, Greater Cairo, Egypt | |
| CN102764759B (en) | Remediation agent for treating arsenic contaminated soil and usage of remediation agent | |
| Tampouris et al. | Removal of contaminant metals from fine grained soils, using agglomeration, chloride solutions and pile leaching techniques | |
| Battaglia et al. | Reduction of Pb and Zn bioavailable forms in metal polluted soils due to paper mill sludge addition: Effects on Pb and Zn transferability to barley | |
| CN107282617B (en) | Polycyclic aromatic hydrocarbon-heavy metal contaminated soil remediation method | |
| Li et al. | Combined sieving and washing of multi-metal-contaminated soils using remediation equipment: A pilot-scale demonstration | |
| CN104004524A (en) | Environmental-friendly heavy metal stabilizer and application method thereof | |
| CN104525123A (en) | Porous composite material for removing heavy metals in soil and preparation method thereof | |
| CN110423624B (en) | Soil pollution stabilizing and repairing agent, preparation and application | |
| Zhao et al. | Effect of nanohydroxyapatite on cadmium leaching and environmental risks under simulated acid rain | |
| CN109762569B (en) | Heavy metal cadmium and arsenic composite contaminated soil remediation agent and preparation method thereof | |
| CN106903150A (en) | Heavy metal contaminated soil remediation material and application method thereof | |
| CN110079323A (en) | A kind of arsenic, nickel combined pollution place soil remediation stabilizer and its processing method | |
| CN108726823A (en) | The method that greasy filth stabilizes solidification medicament and repairs Heavy Metal Pollution in Sediments soil | |
| CN111286337A (en) | Heavy metal composite contaminated soil remediation agent and soil remediation method using same | |
| Zhou et al. | 10 Behavior of Heavy Metals in Soil: Effect of Dissolved Organic Matter | |
| CN112795383A (en) | Multiple heavy metal compound contaminated soil remediation agent and application method thereof | |
| Japenga et al. | Effect of liquid animal manure application on the solubilization of heavy metals from soil | |
| CN108359475A (en) | A kind of humic-acid kind heavy metal-polluted soil renovation agent and its preparation method and application | |
| Barraoui et al. | Cleanup of sewage sludge spiked with Cd, Cu, and Zn: Sludge quality and distribution of metals in the “soil-plant-water” system | |
| CN107903903A (en) | A kind of solidification and stabilization medicament for being used to repair beryllium pollution soils and sediments |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder | ||
| CP01 | Change in the name or title of a patent holder |
Address after: Unit 2002, 20 / F, block B, phase I, Tianan cloud Valley Industrial Park, 2018 Xuegang Road, Bantian street, Longgang District, Shenzhen, Guangdong 518129 Patentee after: Cecep Tiehan ecological environment Co.,Ltd. Address before: Unit 2002, 20 / F, block B, phase I, Tianan cloud Valley Industrial Park, 2018 Xuegang Road, Bantian street, Longgang District, Shenzhen, Guangdong 518129 Patentee before: SHENZHEN TECHAND ECOLOGICAL ENVIRONMENT Co.,Ltd. |