CN110681692A - Method for repairing heavy metal contaminated soil - Google Patents
Method for repairing heavy metal contaminated soil Download PDFInfo
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- CN110681692A CN110681692A CN201911119614.0A CN201911119614A CN110681692A CN 110681692 A CN110681692 A CN 110681692A CN 201911119614 A CN201911119614 A CN 201911119614A CN 110681692 A CN110681692 A CN 110681692A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
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Abstract
The invention relates to a method for restoring heavy metal contaminated soil, which uses organic acid and seaweed organic polymer oxidant to realize the reduction and conversion of heavy metal in the soil, and uses seaweed organic polymer energy agent to realize the flocculation and sedimentation of the heavy metal. The invention has the beneficial effects that: the method for repairing the heavy metal contaminated soil can effectively change the form of the heavy metal, improve the proportion of the stable state of the heavy metal, and reduce the mobility, solubility and bioavailability of the heavy metal; the organic substances are completely used for reducing, stabilizing and settling heavy metal pollutants in farmland soil, particularly heavy metal cadmium and hexavalent chromium, the soil cultivation function is not damaged, the side effect of soil hardening is avoided, and secondary pollution is avoided; short treatment time, quick effect, easy operation, and suitability for paddy fields and dry fields, especially for cadmium-polluted paddy fields.
Description
Technical Field
The invention belongs to the technical field of soil treatment, and particularly relates to a method for repairing heavy metal contaminated soil.
Background
Heavy metals are pollutants in the ecological environment that have great potential hazards to humans and other life. It is not substantially decomposed by microorganisms in the environment, but can migrate to organisms such as animals and plants when heavy metals are soluble and migratable. Heavy metals can migrate through water and soil to crops and plants for human and animal consumption, and once humans and animals consume these crops and plants containing heavy metals, they are extremely hazardous. The scientific community has long proven the hazard of heavy metals and has been seeking various effective methods to solve the soil heavy metal problem. The heavy metal pollution is feared by the potential and long-term harm, and the heavy metal is not easy to be perceived by people at the initial stage of accumulation in the environment; in contrast to the self-cleaning effect of cyanide, a common organic substance, heavy metal contaminants cannot be self-cleaned by degradation, but can be enriched by the biological food chain. In the process, the heavy metals which are difficult to decompose and easy to remain can be accumulated at a certain part of a human body if entering the human body through food, so that the human body is poisoned chronically and difficultly to cure, and the health and the environmental safety of the human body are greatly damaged. Therefore, the remediation treatment of the soil polluted by the heavy metals, particularly the effective treatment of farmland cultivated land polluted by the heavy metals, is urgent.
In view of the particularity of agricultural cultivated land, the soil remediation treatment of heavy metal contaminated farmland cultivated land, especially the remediation treatment of heavy metal contaminated paddy field, is very difficult and complex. The current method, in summary, basically comprises: adsorb heavy metal through planting the plant, absorb heavy metal through the microorganism, adsorb heavy metal through adding chemical toward soil, change heavy metal form through adding chemical toward soil, improve the pH value through adding chemical toward soil and absorb heavy metal with separation plant roots, replace soil through the physical method. At present, various soil remediation agents, soil conditioners and soil heavy metal treatment agents are used for remediating and treating paddy fields, and the effect of reducing the concentration of heavy metals such as rice cadmium can be achieved more or less. The method has certain effect by changing farming agriculture and adding lime to change the pH value of the soil so as to reduce the probability of absorbing heavy metals by the rice root system. However, these methods have some drawbacks and drawbacks, which are collectively expressed in: the method for adsorbing heavy metal by plants has long time and slow effect, needs farmland fallow, and directly influences the normal cultivation of rice; the method for absorbing heavy metals by microorganisms has poor absorption effect and potential hidden danger on the safety and stability of farmland cultivated land for a long time; the method of adsorbing heavy metals or changing the forms of the heavy metals by chemical substances is adopted, so that the soil has the risk of secondary pollution and the normal farming function of the soil is influenced; after the heavy metal is reduced and stabilized, when a chemical fertilizer or a pesticide is used, the original state is easily recovered. The method for improving the pH value of soil and keeping the paddy field covered with water all the time by changing the agricultural technology and using lime has complex operation and is easy to cause soil hardening and influence the grain yield. The physical method for replacing soil is basically not feasible due to large workload and high cost.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for restoring heavy metal contaminated soil, which is a method for treating heavy metal contaminated farmland soil and reducing the concentration of heavy metal in crops by using an organic treating agent, so that heavy metal pollutants in the contaminated farmland soil are reduced stably and deeply settled.
The invention aims to provide a method for repairing heavy metal contaminated soil.
The method for remediating heavy metal contaminated soil according to the embodiment of the present invention comprises the following steps:
(1) soil pretreatment: introducing irrigation water to cover the heavy metal polluted farmland soil, wherein the irrigation water is 4-6 cm in depth, and repeatedly turning over to obtain muddy soil;
(2) primary repair: respectively spraying an acidic substance and a seaweed organic polymer oxidant into the muddy soil formed in the step (1), repeatedly ploughing again, and standing for 72-90 hours to form primary repair soil, wherein the acidic substance is organic acid or hydrogen peroxide diluent; repeating the primary repairing process for 3-5 times;
(3) further repairing: keeping the surface water depth of the soil to be 4-6 cm, adding a seaweed organic polymer energy agent into the primarily repaired soil formed in the step (2), repeatedly ploughing, standing for 60-120 minutes to make the soil and water alkalescent and make the pH value be 7-8;
(4) stabilizing and topdressing: and (3) after further repairing, standing for 6-7 days, and adding a seaweed organic polymer stabilizer into the soil to stabilize the pH of the soil and water to be 6.5-7.5. Applying organic fertilizer or compound fertilizer to the soil, recovering the normal cultivation function of the soil and improving the fertilizer efficiency of the soil.
In the above steps, the volume of the soil to be treated is calculated according to the product of the farmland area and the soil plowing depth, and then the addition amount of the organic acid or the hydrogen peroxide diluent or the seaweed organic polymer oxidant, the seaweed organic polymer energy agent or the seaweed polymer stabilizer is calculated according to the volume of the soil to be treated.
The method for remedying the heavy metal contaminated soil according to the embodiment of the present invention, wherein the plowing depth is 30-50 cm and the plowing depth of the paddy field is 40 cm in the step (1). The plowing depth is determined according to the deepest depth of the root system of the crop.
According to the method for remediating the heavy metal contaminated soil, according to the specific embodiment of the invention, in the step (2), the volume of the soil to be treated is calculated according to the farmland area and the soil turning depth, the addition amount of the acidic substance and the seaweed organic polymer oxidant is calculated according to the volume of the soil to be treated, and 12 liters of the acidic substance and 2 liters of the seaweed organic polymer oxidant are added to each cubic meter of the soil to be treated.
According to the method for remedying the heavy metal contaminated soil of the embodiment of the invention, in the steps (1) to (3), the time for repeatedly ploughing each mu is not less than 30 minutes.
According to the method for remedying the heavy metal contaminated soil, the preparation method of the seaweed organic polymer oxidant in the step (2) comprises the following steps: stirring deep sea algae to crush, and adding 35% concentrated sulfuric acid to acidify; leaching with 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer oxidant with the pH value of 11.5-13.5.
The method for remediating heavy metal contaminated soil according to the embodiment of the present invention, wherein, in the step (2), the organic acid comprises citric acid, oxalic acid and acetic acid; the hydrogen peroxide diluent is diluted by adopting 35% hydrogen peroxide solution, and the concentration of the diluted hydrogen peroxide solution is 7-10%.
According to the method for remedying the heavy metal contaminated soil, the preparation method of the seaweed organic polymer energy agent in the step (3) comprises the following steps: stirring deep sea algae to crush, standing for 72 hr, adding 3% dilute sulfuric acid to acidify; leaching with 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer energy agent with pH of 11.5-13.5.
According to the method for restoring the heavy metal contaminated soil, in the step (3), the volume of the soil to be processed is calculated according to the area of the farmland and the plowing depth of the soil, the addition amount of the seaweed organic polymer energy agent is calculated according to the volume of the soil to be processed, and 2 liters of the seaweed organic polymer energy agent is added to each cubic meter of the soil to be processed.
According to the method for remedying the heavy metal contaminated soil, the preparation method of the seaweed organic polymer stabilizer in the step (4) comprises the following steps: stirring deep sea algae to crush, and adding 3% dilute sulfuric acid to acidify; leaching with 3% sodium hydroxide, and filtering to obtain the seaweed organic polymer oxidant, wherein the pH value of the seaweed organic polymer oxidant is 6.5-7.5.
According to the method for remedying the heavy metal contaminated soil, in the step (4), the stabilizing agent extracted from the seaweed is added to keep the pH of the soil and the water at 6.5-7.5, wherein the adding amount of the stabilizing agent is 2 liters per cubic meter of soil.
The method for remediating heavy metal contaminated soil according to the embodiment of the present invention, wherein the time taken to complete steps (1) - (4) is 30-45 days.
Algae are algae growing in the sea and have the function of absorbing various inorganic elements in the sea water. Seaweed has been used as a raw material for preparing products such as seaweed gel, sodium alginate and the like, and is widely applied by people. Foreign scientists have succeeded in extracting various extracts from seaweeds and producing related seaweed extract products through many years of research and scientific methods. These seaweed extracts have an adsorptive and adhesive function, as well as other properties.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the method for restoring the heavy metal contaminated soil, the organic acid and the seaweed organic polymer oxidant are used as reducing agents to realize the reduction and conversion of the heavy metal in the soil, and no metal preparation or inorganic acid is added, so that the soil is not damaged or secondarily polluted; the seaweed organic polymer energy agent is used for realizing the flocculation and sedimentation of heavy metals, forming small heavy metal particles such as cadmium in the soil into large particles, and ploughing the soil by a physical method to enable the small heavy metal particles to be sedimented to a deep layer of the soil which is difficult to contact with the root system of the plant, thereby further reducing the probability of heavy metal absorption of the plant;
(2) according to the method for repairing the heavy metal contaminated soil, the seaweed extract is selectively adopted as the stabilizer, so that the pH value of farmland soil and water is maintained between 6.5 and 7.5 and the farmland soil and water are alkalescent.
(3) The method for restoring the heavy metal contaminated soil can effectively change the form of the heavy metal, improve the proportion of the stable state of the heavy metal, and reduce the mobility, solubility and bioavailability of the heavy metal; the organic substances are completely used for reducing, stabilizing and settling heavy metal pollutants in farmland soil, particularly heavy metal cadmium and hexavalent chromium, the soil cultivation function is not damaged, the side effect of soil hardening is avoided, and secondary pollution is avoided; the construction operation is simple, and large-area construction or small-scale treatment is suitable;
(4) the treatment time is short, the effect is quick, the operation is easy, the whole process is 30 to 45 days, the treatment can be finished in the idle stage, and the normal cultivation is not influenced; after the treatment is finished, the stable state change of heavy metals cannot be caused by using the compound fertilizer or the organic fertilizer in the farmland; after the treatment is finished, the pH value of water and soil in the paddy field can be kept between 6.5 and 7.5, so that the effect of further preventing the plant root system from absorbing heavy metals is achieved;
(5) according to the method for restoring the heavy metal contaminated soil, the heavy metal concentration of crops is reduced by processing the heavy metal contaminated soil, and the reduction range of the heavy metal concentration of the crops can reach 70-80% after the crops are processed by the method for restoring the heavy metal contaminated soil; the agricultural chemical and fertilizer which are enriched in the farmland soil for a long time are degraded at the same time;
(6) the method for restoring the heavy metal contaminated soil is suitable for paddy fields and dry farmlands, and is particularly suitable for cadmium contaminated paddy fields.
Drawings
FIG. 1 is a process flow diagram of a method for remediating heavy metal contaminated soil in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
As shown in fig. 1, in some more specific embodiments, the method for remediating heavy metal contaminated soil specifically comprises the following steps:
(1) soil pretreatment: introducing irrigation water to cover the heavy metal polluted farmland soil, wherein the irrigation water is 4-6 cm in depth, and repeatedly turning over to obtain muddy soil;
(2) primary repair: respectively spraying an acidic substance and a seaweed organic polymer oxidant into the muddy soil formed in the step (1), repeatedly ploughing again, and standing for 72-90 hours to form primary repair soil, wherein the acidic substance is organic acid or hydrogen peroxide diluent; repeating the primary repairing process for 3-5 times;
(3) further repairing: keeping the surface water depth of the soil to be 4-6 cm, adding a seaweed organic polymer energy agent into the primarily repaired soil formed in the step (2), repeatedly ploughing, standing for 60-120 minutes to make the soil and water alkalescent and make the pH value be 7-8;
(4) stabilizing and topdressing: and (3) after further remediation, standing for 6-7 days, adding a seaweed organic polymer stabilizer into the soil to stabilize the pH of the soil and water between 6.5-7.5, applying an organic fertilizer or a compound fertilizer to the soil, recovering the normal farming function of the soil and improving the fertilizer efficiency of the soil.
In some more specific embodiments, the method for remediating heavy metal contaminated soil comprises the steps of:
(1) soil pretreatment: cofferdam retaining, introducing irrigation water to cover the heavy metal pollution paddy field soil, the depth of the surface water is 4-6 cm, after the retaining is finished, detecting the pH and ORP index of water and soil, and the result shows that: the pH of water and soil is lower than 6, and the ORP accords with the normal ORP index of the soil; repeatedly ploughing for 3-5 times to ensure that the ploughing depth is 30-50 cm to change into slurry soil; if mechanical plowing is adopted, the plowing time of each mu of paddy field is not less than 30 minutes;
(2) primary repair: obtaining the total volume of the treated soil according to the area of the treated soil multiplied by the soil plowing depth (excluding the surface water storage depth), and calculating the total amount of the required organic acid according to 12 liters of organic acid per cubic meter of the treated soil; uniformly spraying organic acid (which can also be sprayed mechanically and has better effect) into the muddy soil formed in the step (1), wherein the organic acid is 10-30% of citric acid, and immediately and repeatedly ploughing; then, the seaweed organic polymer oxidant is uniformly sprayed into the muddy soil manually (or mechanically sprayed with better effect), and then is immediately and repeatedly ploughed for more than 3 times, the ploughing depth is 40 cm, and the soil is kept stand for 72 to 90 hours to form primary repair soil; measuring ORP and pH of water and soil, recovering ORP index of the soil before treatment construction after the ORP is kept still for 72 hours, increasing the pH value to 9.5-10, and then gradually decreasing the pH value to 7-8; repeating the step (2) for 3 times, and repeating for at least 5 times or more if the pollution degree of the treated soil with the heavy metals is extremely high;
(3) further repairing: keeping the surface water depth of the soil to be 4-6 cm, and if the surface water depth is insufficient, irrigating to keep the surface water depth to be 5 cm; adding a seaweed organic polymer energy agent into the primarily-repaired soil formed in the step (2), repeatedly ploughing, standing for 60-120 minutes to make the soil and water alkalescent and make the pH value of the soil and water 7-8; detecting ORP and pH of the soil and water, if the pH is between 7 and 8, the ORP index is in the normal ORP index of the soil, and finishing the treatment; if the pH value is higher than 8, continuing to stand until the pH value is between 7 and 8;
(4) stabilizing and topdressing: and (3) after further repairing, standing for 6-7 days, and adding a seaweed organic polymer stabilizer into the soil to stabilize the pH of the soil and water to be 6.5-7.5. Applying organic fertilizer, bacterial fertilizer or compound fertilizer to the soil, recovering the normal farming function of the soil, improving the fertilizer efficiency of the soil, after one-time or multiple-time fertilization, standing for 15 days, and then farming the rice according to the normal rice farming agricultural technology.
Example 1
The embodiment provides a method for repairing heavy metal contaminated soil, which comprises the following steps:
(1) soil pretreatment: introducing irrigation water to cover the heavy metal polluted farmland soil, wherein the irrigation water is 5 cm in depth, and repeatedly turning over to obtain muddy soil;
(2) primary repair: respectively spraying oxalic acid and a seaweed organic polymer oxidant into the muddy soil formed in the step (1), repeatedly ploughing again, standing for 72 hours to form primary repair soil, and repeating the primary repair process for 4 times;
(3) further repairing: keeping the depth of water on the surface layer of the soil to be 5 cm, adding a seaweed organic polymer energy agent into the primarily repaired soil formed in the step (2), repeatedly ploughing, standing for 100 minutes to make the soil and water in alkalescence and make the pH value be 7.5;
(4) stabilizing and topdressing: and (3) after further remediation, standing for 6.5 days, topdressing the organic fertilizer or the compound fertilizer on the soil, recovering the normal farming function of the soil and improving the fertilizer efficiency of the soil.
Example 2
The embodiment provides a method for repairing heavy metal contaminated soil, which comprises the following steps:
(1) soil pretreatment: cofferdam retaining, introducing irrigation water and covering heavy metal pollution paddy field soil, surface layer water degree of depth 5 centimetres, the retaining is accomplished the back, detects the pH and the ORP index of water and soil, and the result shows: the pH of water and soil is 5.5, and the ORP accords with the normal ORP index of the soil; repeatedly ploughing for 3 times to ensure that the ploughing depth is 40 cm so as to change the ploughed soil into muddy soil; if mechanical plowing is adopted, the plowing time of each mu of paddy field is not less than 30 minutes;
(2) primary repair: obtaining the total volume of the treated soil according to the area of the treated soil multiplied by the soil plowing depth (excluding the surface water storage depth), and calculating the total amount of the required organic acid according to 12 liters of organic acid per cubic meter of the treated soil; manually and uniformly spraying organic acid into the slurry soil formed in the step (1), wherein the organic acid is 20% of citric acid, and immediately and repeatedly ploughing; then 2 liters of seaweed organic polymer oxidant is manually and evenly sprayed into the muddy soil, and the soil is immediately and repeatedly ploughed for 3 times, the ploughing depth is 40 cm, and the soil is kept stand for 80 hours to form primary repair soil; measuring ORP and pH of water and soil, recovering ORP index of the soil before treatment construction after the ORP is kept still for 72 hours, increasing the pH value to 9.8, and then gradually decreasing to 7.5; the preparation method of the seaweed organic polymer oxidant comprises the following steps: stirring deep sea algae to crush, and adding 35% concentrated sulfuric acid to acidify; leaching with 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer oxidant, wherein the pH value of the seaweed organic polymer oxidant is 11.5; repeating the step (2) for 3 times;
(3) further repairing: keeping the surface water depth of the soil to be 5 cm, and if the surface water depth is insufficient, irrigating to keep the surface water depth to be 5 cm; adding 2 liters of seaweed organic polymer energy agent into the primarily repaired soil formed in the step (2), repeatedly ploughing, standing for 80 minutes to make the soil and water alkalescent and make the pH value of the soil and water 7.5; detecting ORP and pH of the soil and water, if the pH is between 7.5, the ORP index is in the normal ORP index of the soil, and finishing the treatment; the preparation method of the seaweed organic polymer energy agent comprises the following steps: stirring deep sea algae to crush, and adding 3% dilute sulfuric acid to acidify; leaching with 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer energy agent, wherein the pH value of the seaweed organic polymer energy agent is 12.0;
(4) stabilizing and topdressing: after further repairing, standing for 6.5 days, adding 2 liters of seaweed organic polymer stabilizer into the soil, dressing organic fertilizer, bacterial fertilizer or compound fertilizer on the soil, recovering the normal farming function of the soil, improving the soil fertility, and after finishing one-time or multi-time fertilization, standing for 15 days, and then farming the rice according to the normal rice farming agricultural process;
(5) adjusting the pH of the soil: during the growth of the rice, the pH value is detected every week or two weeks, the pH value is obviously reduced, when the pH value is lower than 7, the seaweed organic polymer stabilizer is added for adjustment, and the pH value is adjusted to be 7.5; the addition amount of the stabilizer is 2 liters per cubic meter of soil; the preparation method of the seaweed organic polymer stabilizer comprises the following steps: stirring deep sea algae to crush, and adding 3% dilute sulfuric acid to acidify; leaching with 3% sodium hydroxide, and filtering to obtain the seaweed organic polymer oxidant, wherein the pH value of the seaweed organic polymer oxidant is 7.0.
Example 3
As shown in fig. 1, the present embodiment provides a method for remediating heavy metal contaminated soil, including the following steps:
(1) soil pretreatment: cofferdam retaining, introducing irrigation water and covering heavy metal pollution paddy field soil, surface layer water degree of depth 5 centimetres, the retaining is accomplished the back, detects the pH and the ORP index of water and soil, and the result shows: the pH of water and soil is 5.5, and the ORP accords with the normal ORP index of the soil; repeatedly ploughing for 3 times to ensure that the ploughing depth is 40 cm so as to change the ploughed soil into muddy soil; if mechanical plowing is adopted, the plowing time of each mu of paddy field is not less than 30 minutes;
(2) primary repair: obtaining the total volume of the treated soil according to the area of the treated soil multiplied by the soil plowing depth (excluding the surface water storage depth), and calculating the total amount of the required organic acid according to 12 liters of organic acid per cubic meter of the treated soil; manually and uniformly spraying organic acid into the slurry soil formed in the step (1), wherein the organic acid is 20% of citric acid, and immediately and repeatedly ploughing; then 2 liters of seaweed organic polymer oxidant is manually and evenly sprayed into the muddy soil, and the soil is immediately and repeatedly ploughed for 3 times, the ploughing depth is 40 cm, and the soil is kept stand for 80 hours to form primary repair soil; measuring ORP and pH of water and soil, recovering ORP index of the soil before treatment construction after the ORP is kept still for 72 hours, increasing the pH value to 9.8, and then gradually decreasing to 7.5; the preparation method of the seaweed organic polymer oxidant comprises the following steps: stirring deep sea algae to crush, and adding 35% concentrated sulfuric acid to acidify; leaching with 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer oxidant, wherein the pH value of the seaweed organic polymer oxidant is 13.1; repeating the step (2) for 3 times;
(3) further repairing: keeping the surface water depth of the soil to be 5 cm, and if the surface water depth is insufficient, irrigating to keep the surface water depth to be 5 cm; adding 2 liters of seaweed organic polymer energy agent into the primarily repaired soil formed in the step (2), repeatedly ploughing, standing for 80 minutes to make the soil and water alkalescent and make the pH value of the soil and water 7.5; detecting ORP and pH of the soil and water, if the pH is between 7.5, the ORP index is in the normal ORP index of the soil, and finishing the treatment; the preparation method of the seaweed organic polymer energy agent comprises the following steps: stirring deep sea algae to crush, and adding 3% dilute sulfuric acid to acidify; leaching with 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer energy agent, wherein the pH value of the seaweed organic polymer energy agent is 13.1;
(4) stabilizing and topdressing: after further repairing, standing for 6.5 days, adding 2 liters of seaweed organic polymer stabilizer into the soil, dressing organic fertilizer, bacterial fertilizer or compound fertilizer on the soil, recovering the normal farming function of the soil, improving the soil fertility, and after finishing one-time or multi-time fertilization, standing for 15 days, and then farming the rice according to the normal rice farming agricultural process;
(5) adjusting the pH of the soil: during the growth of the rice, the pH value is detected every week or two weeks, the pH value is obviously reduced, when the pH value is lower than 7, the seaweed organic polymer stabilizer is added for adjustment, and the pH value is adjusted to be between 7 and 8; the addition amount of the stabilizer is 2 liters per cubic meter of soil; the preparation method of the seaweed organic polymer stabilizer comprises the following steps: stirring deep sea algae to crush, and adding 3% dilute sulfuric acid to acidify; leaching with 3% sodium hydroxide, and filtering to obtain the seaweed organic polymer oxidant, wherein the pH value of the seaweed organic polymer oxidant is 6.5.
After the paddy field soil is repaired by the method of example 3, the content of heavy metals such as the available state of heavy metals, the paddy yield and the cadmium concentration of rice in the soil is detected, and the detection results of the content of the heavy metals in the available state are shown in table 1:
TABLE 1 detection results of the content of the effective state of heavy metals in soil
| Region(s) | Mg/kg before treatment | Mg/kg after | Reduction ratio | |
| 1 | 1.509 | 0.215 | 85.75％ | |
| 2 | 1.562 | 0.417 | 73.3％ |
The detection results of the concentration of cadmium in rice are shown in table 2, wherein the area 3 is the result of planting rice in soil which is not treated by the method for repairing heavy metal contaminated soil of the invention:
TABLE 2 detection of cadmium concentration in Rice (unit: mg/kg)
After the remediation treatment of the paddy field soil is completed according to the method in example 3, the rate of the decrease of the effective state of the heavy metals in the soil is detected to reach 70-80%. After the rice is harvested, the total yield is not reduced but slightly improved, the concentration of heavy metals such as cadmium in the rice is reduced by 70-80%, and the yield of the rice is increased by 5-10%.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. A method for remediating heavy metal contaminated soil, comprising the steps of:
(1) soil pretreatment: introducing irrigation water to cover the heavy metal polluted farmland soil, wherein the irrigation water is 4-6 cm in depth, and repeatedly turning over to obtain muddy soil;
(2) primary repair: respectively spraying an acidic substance and a seaweed organic polymer oxidant into the muddy soil formed in the step (1), repeatedly ploughing again, and standing for 72-90 hours to form primary repair soil, wherein the acidic substance is organic acid or hydrogen peroxide diluent; repeating the primary repairing process for 3-5 times;
(3) further repairing: keeping the surface water depth of the soil to be 4-6 cm, adding a seaweed organic polymer energy agent into the primarily repaired soil formed in the step (2), repeatedly ploughing, standing for 60-120 minutes to make the soil and water alkalescent and make the pH value be 7-8;
(4) stabilizing and topdressing: and (3) after further remediation, standing for 6-7 days, adding the seaweed organic polymer stabilizer into the remediated soil to enable the pH of the soil and water to be 6.5-7.5, applying an organic fertilizer or a compound fertilizer to the soil, recovering the normal farming function of the soil and improving the fertilizer efficiency of the soil.
2. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the step (1), the plowing depth is 30-50 cm, and the plowing depth of the paddy field is 40 cm.
3. The method for remediating heavy metal contaminated soil as recited in claim 2, wherein in the step (2), the volume of the soil to be treated is calculated according to the farmland area and the soil plowing depth, the addition amounts of the acidic substance and the seaweed organic polymer oxidant are calculated according to the volume of the soil to be treated, and 12 liters of the acidic substance and 2 liters of the seaweed organic polymer oxidant are added to each cubic meter of the soil to be treated.
4. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the steps (1) to (3), the time for repeatedly plowing per mu is not less than 30 minutes.
5. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the step (2), the seaweed organic polymer oxidant is prepared by: stirring deep sea algae to crush, and adding 35% concentrated sulfuric acid to acidify; leaching with 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer oxidant with the pH value of 11.5-13.5.
6. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the step (2), the organic acid comprises citric acid, oxalic acid and acetic acid; the hydrogen peroxide diluent is diluted by adopting 35% hydrogen peroxide solution, and the concentration of the diluted hydrogen peroxide solution is 7-10%.
7. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the step (3), the preparation method of the seaweed organic polymer energy agent comprises: stirring deep sea algae to crush, standing for 72 hours, adding 3% diluted sulfuric acid to acidify the deep sea algae, leaching by adopting 35% sodium hydroxide, and filtering to obtain the seaweed organic polymer energy agent, wherein the pH value of the seaweed organic polymer energy agent is 11.5-13.5.
8. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the step (3), the volume of the soil to be treated is calculated according to the area of the agricultural field and the plowing depth of the soil, the addition amount of the seaweed organic polymer energy agent is calculated according to the volume of the soil to be treated, and 2 liters of the seaweed organic polymer energy agent is added to each cubic meter of the soil to be treated.
9. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in step (4), the pH of the soil and the water are maintained between 6.5 and 7.5 by adding the seaweed organic polymer stabilizer, wherein the amount of the stabilizer is 2 liters per cubic meter of soil.
10. The method for remediating heavy metal contaminated soil as recited in claim 1, wherein in the step (4), the seaweed organic polymer stabilizer is prepared by: stirring deep sea algae to crush, standing for 72 hours, adding 3% diluted sulfuric acid to acidify the deep sea algae, leaching by using 3% sodium hydroxide, and filtering to obtain the organic seaweed polymer stabilizer, wherein the pH value of the organic seaweed polymer energy agent is 6.5-7.5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201911119614.0A CN110681692B (en) | 2019-11-15 | 2019-11-15 | Method for repairing heavy metal contaminated soil |
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| CN111451267A (en) * | 2020-03-14 | 2020-07-28 | 华中师范大学 | Electrochemical in-situ automatic control contaminated site remediation system and method |
| CN112169571A (en) * | 2020-10-23 | 2021-01-05 | 斯蒂芬·Y·周 | Method for treating malodorous gas and VOC |
| CN112282678A (en) * | 2020-10-23 | 2021-01-29 | 斯蒂芬·Y·周 | Treatment method of shale gas oil-based drilling cutting solid waste |
| CN112404112A (en) * | 2020-09-30 | 2021-02-26 | 广州草木蕃环境科技有限公司 | Layered replacement and restoration method for mercury-polluted farmland |
| CN112974505A (en) * | 2021-01-28 | 2021-06-18 | 中国电建集团江西省电力建设有限公司 | Method for restoring rice field soil cadmium pollution by using activator and nitrogen-fixing blue algae |
| CN114210727A (en) * | 2021-12-17 | 2022-03-22 | 生态环境部南京环境科学研究所 | Preparation method of heavy metal contaminated soil phytoremediation enhancer |
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| CN111451267A (en) * | 2020-03-14 | 2020-07-28 | 华中师范大学 | Electrochemical in-situ automatic control contaminated site remediation system and method |
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| CN112974505A (en) * | 2021-01-28 | 2021-06-18 | 中国电建集团江西省电力建设有限公司 | Method for restoring rice field soil cadmium pollution by using activator and nitrogen-fixing blue algae |
| CN112974505B (en) * | 2021-01-28 | 2021-12-24 | 中国电建集团江西省电力建设有限公司 | Method for restoring rice field soil cadmium pollution by using activator and nitrogen-fixing blue algae |
| CN114210727A (en) * | 2021-12-17 | 2022-03-22 | 生态环境部南京环境科学研究所 | Preparation method of heavy metal contaminated soil phytoremediation enhancer |
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