阅读说明：本技术 一种重金属污染土壤钝化的方法 (Method for passivating heavy metal contaminated soil ) 是由 肖满 杨鹤峰 万鹏 卜繁婷 王轶嘉 于 2020-06-03 设计创作，主要内容包括：本发明提供了一种重金属污染土壤钝化的方法,包括如下步骤：钝化施工：在重金属污染土壤上依次施撒钝化剂、旋耕、打浆、第一次静置和第一次排水；余量去除：大水漫灌至水面高于钝化施工后土壤的地表,第二次静置,第二次排水。通过氧化环境下旋耕混合和还原环境下打浆混合配合进行,提高施工效率、促进钝化剂和重金属的反应；同时促进钝化剂再分配以及污染土壤均衡钝化；通过在钝化施工后,即钝化剂充分反应后,采用大水漫灌至水面高于钝化施工后土壤的地表,静置,可有效促进钝化剂的再分配工作以及污染土壤均衡钝化,最后通过排水对污染程度较低(需钝化剂少)的区域进行多余钝化剂的去除,有效地修复土壤,提高钝化效果及作物产量。(The invention provides a method for passivating heavy metal contaminated soil, which comprises the following steps: passivation construction: sequentially spreading a passivating agent, rotary tillage, pulping, standing for the first time and draining for the first time on the heavy metal contaminated soil; and (4) removing the allowance: and (5) flood irrigation is carried out until the water surface is higher than the ground surface of the soil after passivation construction, standing for the second time, and draining for the second time. The rotary tillage mixing in the oxidation environment and the pulping mixing in the reduction environment are matched, so that the construction efficiency is improved, and the reaction of the passivating agent and the heavy metal is promoted; meanwhile, the redistribution of the passivator and the balanced passivation of the polluted soil are promoted; after passivation construction, namely after the passivator fully reacts, the water is flooded to the ground surface of the soil with the water surface higher than the soil after passivation construction, standing is carried out, redistribution work of the passivator and balanced passivation of the polluted soil can be effectively promoted, and finally, redundant passivator is removed from an area with low pollution degree (less passivator is needed) through drainage, so that the soil is effectively repaired, and the passivation effect and the crop yield are improved.)

1. The method for passivating the heavy metal contaminated soil is characterized by comprising the following steps of:

passivation construction: sequentially spreading a passivating agent, rotary tillage, pulping, standing for the first time and draining for the first time on the heavy metal contaminated soil;

and (4) removing the allowance: and (5) flood irrigation is carried out until the water surface is higher than the ground surface of the soil after passivation construction, standing for the second time, and draining for the second time.

2. The method for passivating the soil polluted by the heavy metal according to claim 1, wherein the large water is flood-irrigated to the water surface 15-20cm higher than the ground surface of the soil after passivation construction.

3. The method for passivating heavy metal contaminated soil according to claim 1 or 2, wherein the second standing time is 2-3 days.

4. The method for passivating heavy metal contaminated soil according to any of claims 1 to 3, wherein the second water discharge is performed to a level 5 to 10cm above the ground surface.

5. The method for passivating heavy metal contaminated soil according to any of claims 1-4, wherein the rotary tillage depth is less than 20 cm;

in the pulping step, the heavy metal polluted soil after rotary tillage is subjected to flood irrigation until the water surface is 15-20cm higher than the ground surface, and then the soil is pulped until the soil and water form uniform suspension;

the first standing time is 24-48 h;

the first drainage is to release water below the soil surface layer by using the gravity of the irrigation canal.

6. The method for passivating the soil polluted by the heavy metal according to any one of claims 1 to 5, wherein the passivating agent comprises a liquid medicament and a granular medicament, wherein the mass ratio of an effective component in the liquid medicament to an effective component in the granular medicament is 1 (51-81).

7. The method for passivating heavy metal contaminated soil according to any one of claims 1 to 6, wherein the passivating agent is applied in an amount of 1.0 to 2.1kg/m²。

8. The method for passivating heavy metal contaminated soil according to any one of claims 1 to 7, further comprising, before passivation construction, the steps of:

draining and leveling the field: after the farmland is drained of water or before the farmland with the straws is covered with water is irrigated, the straws on the ground surface are cleaned and the field is leveled;

preparing a passivating agent: and (4) sampling and detecting the quality of the passivator, and spraying after the passivator is detected to be qualified.

9. The method for passivating heavy metal contaminated soil according to any of claims 1 to 8, wherein the concentration of lead in the heavy metal contaminated soil is 2.5 to 5.2mg/kg, and the concentration of cadmium in the heavy metal contaminated soil is 0.3 to 1.7 mg/kg.

10. The method for passivating heavy metal-contaminated soil according to any one of claims 6 to 9, wherein the application of the particulate agent is performed using an applicator;

the scattering machine includes:

the travelling mechanism comprises a guide wheel arranged on the front side of the spreading machine body, a first driving shaft arranged on the rear side of the spreading machine body and a driving wheel driven by the first driving shaft to rotate;

the center of gravity of the medicine adding tank is positioned on the vehicle body in front of the first driving shaft;

the counterweight is arranged on the vehicle body, and the gravity center of the counterweight is positioned on the vehicle body behind the first driving shaft;

the pesticide spraying mechanism is arranged on the vehicle body in front of a second driving shaft for driving the guide wheel;

and the liquid pump is arranged on the vehicle body between the first driving shaft and is respectively communicated with the dosing tank and the pesticide spraying mechanism.

Technical Field

The invention relates to the field of heavy metal contaminated soil treatment, in particular to a method for passivating heavy metal contaminated soil.

Background

With the rapid increase of economy, the soil environment quality is not optimistic on the whole, and especially the cultivated land environment quality is worried. The heavy metal pollution of the farmland soil has the characteristics of concealment, long-term property, irreversibility and the like, and directly threatens the safety of agricultural products and the health of human bodies, so the prevention and the treatment of the heavy metal soil pollution are the most important of the current soil treatment.

At present, aiming at the prevention and treatment of heavy metal soil pollution, common restoration methods can be generally divided into a physical restoration method, a chemical passivation restoration method, a biological restoration method and an agricultural ecological restoration method, wherein the chemical passivation restoration technology has the advantages of low investment, simple use method, small influence on agricultural production, good restoration effect, quick response and the like, and is widely applied to the restoration of the heavy metal polluted soil. The chemical passivation repairing technology is characterized in that the passivator is used for influencing the form distribution of heavy metals, converting extractable heavy metals into residue heavy metals and further changing the activity of the heavy metals in soil, and the mechanism is that the passivator and the metals reduce the activity of the heavy metals through the actions of precipitation fixation, adsorption and ion exchange, ion antagonism or chelation and the like.

For example, chinese patent document CN109628099A discloses a method for using a passivation stabilizer for farmland soil cadmium pollution remediation, which comprises the following steps: (1) ploughing and drying the field, crushing the soil block mass, and adding the passivation stabilizer; (2) after the passivation stabilizer is sowed, carrying out rotary tillage on the dry soil, carrying out longitudinal and transverse rotary tillage for 3 times, wherein the rotary tillage depth is 15-20cm, ensuring that the dry soil is uniformly mixed horizontally and vertically, and standing for 10-20 days after the rotary tillage; (3) after the rotary tillage is finished, adding water until the water level is 10-12cm higher than the surface of the soil, aging the soil, and carrying out rotary tillage operation on the soil by using a rotary cultivator during the aging period; (4) and (5) standing the farmland added with the passivation stabilizer for 12-15 days, and drying the farmland in the sun. As a limit, according to the cadmium pollution degree, the application amount of the passivator for each mu of land with the cadmium content lower than 1mg/kg is 400-800 kg; the cadmium content of the farmland soil is higher than 1mg/kg, and the application amount of the passivator per mu is 1000-1500 kg.

Although the use method of the passivation stabilizer for farmland soil cadmium pollution remediation disclosed by the above document reduces the effective state content of cadmium in soil, the method does not affect farming season; however, it has poor inactivation effect and low crop yield.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects of poor passivation effect and low crop yield of the method for passivating the heavy metal contaminated soil in the prior art, thereby providing a method for passivating the heavy metal contaminated soil.

Therefore, the invention provides the following technical scheme:

a method for passivating heavy metal contaminated soil comprises the following steps:

passivation construction: sequentially spreading a passivating agent, rotary tillage, pulping, standing for the first time and draining for the first time on the heavy metal contaminated soil;

and (4) removing the allowance: and (5) flood irrigation is carried out until the water surface is higher than the ground surface of the soil after passivation construction, standing for the second time, and draining for the second time.

Further, the large water is flood-irrigated to the position that the water surface is 15-20cm higher than the ground surface of the soil after passivation construction.

Further, the second standing time is 2-3 days.

Further, draining for the second time until the water level is 5-10cm higher than the ground surface.

Further, the rotary tillage depth is less than 20 cm; preferably, the rotary tillage depth is 5-20 cm;

in the pulping step, the heavy metal polluted soil after rotary tillage is subjected to flood irrigation until the water surface is 15-20cm higher than the ground surface, and then the soil is pulped until the soil and water form uniform suspension;

the first standing time is 24-48 h;

the first drainage is to release water below the soil surface layer by using the gravity of the irrigation canal.

Further, the passivating agent comprises a liquid medicament and a granular medicament, and the mass ratio of the effective components in the liquid medicament to the effective components in the granular medicament is 1 (51-81).

The liquid medicament can be prepared into liquid medicaments with different effective component contents according to the properties of different heavy metal polluted soil, and the type of equipment for spraying the liquid medicament can be flexibly adjusted according to the characteristics and site conditions of the medicament and the safety of the operation process.

Further, the liquid medicament can be an alkaline liquid medicament, the alkalinity of the liquid medicament can passivate heavy metals, and a natural mineral promoter can be added into the alkaline liquid medicament to promote the dissolution of the alkaline medicament and ensure the solubility and stability of the solution of the alkaline medicament.

Furthermore, the acidic particle medicament can be selected to passivate heavy metals and neutralize alkaline liquid medicament, so that the pH value of soil is further optimized, the passivation effect is improved, and the crop yield is increased.

Furthermore, natural mineral components and organic matters can be simultaneously added into the liquid medicament, so that the air permeability and the fertility of the soil can be further improved, and the crop yield can be increased.

Furthermore, the application amount of the passivator is 1.0-2.1kg/m²。

Further, before passivation construction, the method also comprises the following steps:

draining and leveling the field: after the water is drained from the flood irrigation farmland or before the irrigation of the farmland covered with the straws, the straws on the ground surface are cleaned and the field is leveled;

preparing a passivating agent: and (4) sampling and detecting the quality of the passivator, and spraying after the passivator is detected to be qualified.

Sampling detection qualified standard: the granular medicament is subjected to sampling inspection for 30 times, wherein the results of 30 times of sampling inspection all meet the standard of GB18877-2009 organic-inorganic compound fertilizer, namely the granular medicament in the passivator subjected to sampling inspection is qualified; the liquid medicament is subjected to sampling inspection for 30 times, wherein the results of 30 sampling inspections all accord with the standard of GB18877-2009 organic-inorganic compound fertilizer, namely the liquid medicament in the passivator subjected to sampling inspection is qualified. The detection method for the content of each metal in the liquid medicament and the particle medicament comprises the following steps:

the lead detection method comprises the following steps: the standard of the atomic absorption spectrometry is ecological indexes of arsenic, cadmium, lead, chromium and mercury in fertilizers (GB/T23349-20094.2.4);

the detection method of arsenic comprises the following steps: the standard of the ultraviolet visible spectrophotometry is ecological indexes of arsenic, cadmium, lead, chromium and mercury in the fertilizer (GB/T23349-20094.2.1);

the mercury detection method comprises the following steps: cold atomic absorption spectrophotometry, standard is ecological indexes of arsenic, cadmium, lead, chromium and mercury in fertilizer (GB/T23349-20094.2.6);

the detection method of cadmium comprises the following steps: the standard of the atomic absorption spectrometry is ecological indexes of arsenic, cadmium, lead, chromium and mercury in fertilizers (GB/T23349-20094.2.3);

the detection method of chromium comprises the following steps: the standard of the atomic absorption spectrometry is ecological indexes of arsenic, cadmium, lead, chromium and mercury in fertilizers (GB/T23349-20094.2.5).

Furthermore, the concentration of lead in the heavy metal polluted soil is 2.5-5.2mg/Kg, and the concentration of cadmium in the heavy metal polluted soil is 0.3-1.7 mg/Kg.

Further, a spreading machine is adopted to spread granular medicaments;

the scattering machine includes:

the travelling mechanism comprises a guide wheel arranged on the front side of the spreading machine body, a first driving shaft arranged on the rear side of the spreading machine body and a driving wheel driven by the first driving shaft to rotate;

the center of gravity of the medicine adding tank is positioned on the vehicle body in front of the first driving shaft;

the counterweight is arranged on the vehicle body, and the gravity center of the counterweight is positioned on the vehicle body behind the first driving shaft;

the pesticide spraying mechanism is arranged on the vehicle body in front of a second driving shaft for driving the guide wheel;

and the liquid pump is arranged on the vehicle body between the first driving shaft and is respectively communicated with the dosing tank and the pesticide spraying mechanism.

Further, the counterweight is arranged at the end part of the vehicle body; the end part of the vehicle body is one end of the spreading machine, close to the first driving shaft, and the weight of the spreading machine can be effectively reduced while the weight of two sides of the first driving shaft is balanced by arranging the balance weight at the end part of the vehicle body.

Furthermore, a fixed frame is arranged on the vehicle body, and the balance weight is arranged on the fixed frame. The counterweight can be conveniently installed on the vehicle body by a user through the fixed frame, so that the user can use and operate the counterweight conveniently.

Furthermore, the fixing frame is an accommodating cavity arranged at the tail end of the vehicle body, and the balance weight is arranged in the accommodating cavity. The balance weight can be placed in the accommodating cavity simply and conveniently according to actual needs by a user through the accommodating cavity, and the balance weight is convenient for the user to operate and use.

Furthermore, the spreading machine also comprises a control module positioned on the vehicle body, the control module is used for controlling the spreading machine to spray the pesticide, and the control module comprises a signal receiver which receives a control signal to control the spreading machine. The pesticide spreading function can be realized by remotely controlling the spreading machine by a user through the control module, so that an operator can finish pesticide spreading work without the need of the spreading machine. The weight of the spreader is reduced, so that the guide wheels and the driving wheels bear smaller weight, and the problem of soil hardening caused by the fact that the spreader rolls soil is prevented.

Further, the control module is positioned at the front side of the second driving shaft and close to the pesticide spraying mechanism.

Further, the medicine spraying mechanism and/or the medicine adding tank and/or the liquid pump are/is coaxially arranged on the central axis of the vehicle body. Through will spout medicine mechanism and/or add the medicinal cupping and/or drawing liquid pump coaxial setting on the axis of automobile body, can prevent effectively that one of them side in the machine left and right sides of scattering is heavier, and then appear inclining, lead to scattering the problem that this side that its weight is heavier of machine rolls soil and appear hardening, can prevent effectively through balanced weight that scattering machine rolls soil and appear hardening, and the counter weight of machine of scattering is executed to the equilibrium under the prerequisite that does not increase scattering machine weight as far as possible effectively, guarantee to spread the frictional force between machine and the ground.

Further, the center of gravity of the counterweight and the center of gravity of the control module are located on different sides of the center line in the longitudinal direction of the vehicle body. Because a medicine conveying pipe needs to be arranged between the medicine adding tank and the liquid drawing pump, and in order to ensure that the medicine spraying mechanism, the medicine adding tank and the liquid drawing pump are coaxially arranged on the central axis of the vehicle body, the balance weight cannot be arranged on the central axis of the vehicle body, and the applicator can be inclined. The center of gravity of the counterweight and the center of gravity of the control module are located on different sides of the center line of the vehicle body in the longitudinal direction. The gravity center of the counterweight and the gravity center of the control module are arranged on different sides of the center line of the vehicle body in the length direction, so that the counterweight can play a role in balancing the weight of the left side and the right side of the spreading machine, the stability of the vehicle body of the spreading machine is enhanced, and the climbing capacity is improved. Moreover, the problem that the soil rolled by the side with the heavier weight of the spreader is hardened due to the fact that one of the left side and the right side of the spreader is heavier and further inclines is solved, and the soil rolled by the spreader can be effectively prevented from being hardened through balancing the weight; and effectively balance the balance weight of the spreader on the premise of not increasing the weight of the spreader as much as possible, and ensure the friction force between the spreader and the ground.

Further, the fixing frame comprises a first cavity and a second cavity which are respectively positioned on two sides of the central line of the car body in the length direction.

Through the first cavity and the second cavity that will be used for placing the counter weight set up respectively in the length direction of automobile body central line both sides to make the user can be according to the in-service use needs, the counter weight of the quick-witted left and right sides is executed in the adjustment, avoid executing the too big weight of one of them side of scattering the machine, the problem that hardens appears in the too big this side of scattering the machine weight rolling soil, and in the prerequisite of not increasing the weight of scattering the machine of executing effectively the balance of scattering the machine, guarantee to execute the frictional force between machine and the ground of scattering.

Furthermore, the applicator also comprises a driving motor which is arranged on the central line of the length direction of the vehicle body and is used for driving the first driving shaft to rotate. Through the driving motor, the problem that the soil rolled by the side with heavier weight of the spreader is hardened due to the fact that one side of the left side and the right side of the spreader is heavier and the spreader is inclined can be prevented

Further, the spraying mechanism includes: the rotary disc water storage pipe is communicated with the liquid pump, and the plurality of pesticide spraying branch pipes are arranged along the circumferential direction of the rotary disc water storage pipe, and nozzles are arranged on the pesticide spraying branch pipes. Through the wheel disc water storage pipe and the plurality of pesticide spraying branch pipes arranged along the circumferential direction of the wheel disc water storage pipe, the pesticide spraying machine can effectively and uniformly spray pesticide towards all directions.

Further, the spraying branch pipe is a telescopic pipe. The spraying branch pipes are arranged to be telescopic pipes, so that the spreading machine can meet the demand of inter-ridge division of the farmland at present, and the spraying branch pipes can be freely extended or shortened according to actual conditions so as to meet the demand of spraying of individual small-range partial plots.

The technical scheme of the invention has the following advantages:

1. the method for passivating the heavy metal contaminated soil provided by the invention comprises the following steps: passivation construction: sequentially spreading a passivating agent, rotary tillage, pulping, standing for the first time and draining for the first time on the heavy metal contaminated soil; and (4) removing the allowance: and (5) flood irrigation is carried out until the water surface is higher than the ground surface of the soil after passivation construction, standing for the second time, and draining for the second time.

The inventor finds out through research that: the soil treated by the existing heavy metal contaminated soil passivation method has the defect of low crop yield; the reason for this is that: heterogeneous characteristics due to soil contamination: heavy metal pollution concentrations in different regions are different, so that in order to completely passivate heavy metals, the passivator is excessive when being added, and the excessive passivator directly causes the over-high content of soil minerals, so that the passivation effect is poor and the crop yield is reduced.

According to the method for passivating the heavy metal contaminated soil, rotary tillage mixing in an oxidizing environment and pulping mixing in a reducing environment are matched, so that the construction efficiency is improved, and the reaction of a passivating agent and heavy metal is promoted; meanwhile, the redistribution of the passivator and the balanced passivation of the polluted soil are promoted; soil hardened by mechanical rolling in the passivating agent spreading process can be loosened through a pulping process; ensuring the air permeability and the medicine-soil mixing uniformity after the soil passivation construction. After passivation construction, namely after the passivator fully reacts, the water is flooded to the ground surface of the soil with the water surface higher than the soil after passivation construction, standing is carried out, redistribution work of the passivator and balanced passivation of the polluted soil can be effectively promoted, and finally, redundant passivator is removed from an area with low pollution degree (less passivator is needed) through drainage, so that the soil is effectively repaired, the passivation effect is improved, and the crop yield is improved. According to the method for passivating the heavy metal contaminated soil, provided by the invention, the passivating construction steps of passivating agent application, rotary tillage, pulping, standing and drainage are combined with the residue removal step, so that the passivating effect can be effectively improved, and the redundant passivating agent can be removed, so that the crop yield is improved.

2. According to the method for passivating the heavy metal contaminated soil, provided by the invention, the large water is limited to flood and irrigate to the position that the water surface is 15-20cm higher than the ground surface of the soil after passivation construction, so that redistribution of the passivating agent can be further promoted, and the passivation effect is improved.

3. The method for passivating the heavy metal contaminated soil provided by the invention can further promote the balanced passivation of the contaminated soil and the redistribution of the passivator by limiting the standing time to 2-3 days, thereby improving the passivation effect and the crop yield.

4. According to the method for passivating the heavy metal contaminated soil, provided by the invention, the water is limited to be drained to a water level 5-10cm higher than the ground surface, so that the redundant passivators are effectively removed, meanwhile, the later-stage fertilization and planting are more convenient, and the crop yield is further improved.

5. According to the method for passivating the heavy metal contaminated soil, provided by the invention, the soil hardened by mechanical rolling in the passivating agent application process can be further loosened by limiting the rotary tillage depth and matching the rotary tillage and pulping processes; ensuring the air permeability and the medicine-soil mixing uniformity after the soil passivation construction.

6. According to the method for passivating the heavy metal contaminated soil, the passivant compounded by the liquid medicament and the granular medicament is adopted, and the proportion of the effective components of the liquid medicament and the granular medicament is limited, so that the content of the heavy metal in the soil in an effective state can be further reduced; and further improve soil fertility, air permeability and soil texture.

7. According to the method for passivating the heavy metal contaminated soil, provided by the invention, the fields are drained before passivation construction, the fields are leveled, and the passivating agent is tested, so that the adding precision of the passivating agent is ensured.

8. According to the method for passivating the heavy metal contaminated soil, the passivating agent is applied by the applying machine, and the spraying time interval of the granular agent and the liquid agent in the passivating agent is not more than 48 hours, so that the loss of the passivating agent in the adding process can be reduced, the adding precision and uniformity are improved, and the requirement of soil repairing and accurate adding is met; and the conventional planting process is not influenced.

9. The method for passivating the heavy metal contaminated soil provided by the invention is based on the aspects of environmental conditions, process conditions, heterogeneous conditions and the like which influence medicament reaction, provides a systematic passivation method, realizes the rapid and accurate construction of soil passivation, combines a passivation material, and is matched with the feature that the combination potential of an effective state and soil particles is less than the absorption potential of a plant root system to scatter the passivation material in a farmland in farming season to promote the reduction of the effective state content of heavy metal in the soil, thereby achieving the purposes of reducing the content of heavy metal elements enriched in plants and not influencing normal agricultural production, and achieving the purpose of considering both farming season and yield.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a flow chart of a method for passivating and planting heavy metal contaminated soil provided in embodiment 1 of the present invention.

Fig. 2 is a schematic structural view of an applicator used in embodiment 1 of the present invention;

fig. 3 is a schematic structural view of an applicator used in embodiment 2 of the present invention.

Description of reference numerals:

1-a guide wheel; 2-a first drive shaft; 3-driving wheels; 4-a medicine adding tank; 5-a medicine spraying mechanism; 6-a second drive shaft; 7-a liquid pump; 8, fixing a frame; 9-a control module; 10-a first cavity; 11-a second cavity; 12-a wheel disc water storage pipe; 13-spraying branch pipes; 14-counterweight.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.