CN110560477A

CN110560477A - Soil remediation agent, preparation method and application thereof, and soil remediation method

Info

Publication number: CN110560477A
Application number: CN201910915043.5A
Authority: CN
Inventors: 李焕茹; 张丽; 毕学; 张琢; 王志新
Original assignee: Beijing Sound Environment Technology Co Ltd
Current assignee: Beijing Sound Environment Technology Co Ltd
Priority date: 2019-09-26
Filing date: 2019-09-26
Publication date: 2019-12-13

Abstract

the invention discloses a soil remediation agent, a preparation method and application thereof, and a soil remediation method. The soil remediation agent comprises, by weight, 7-25 parts of an acidic polymer, 18-45 parts of an organic fertilizer and 30-75 parts of a sulfide. By adopting the acidic polymer, the organic fertilizer and the sulfide and controlling the use proportion of the organic fertilizer and the sulfide, the three generate synergistic effect, can have good repairing effect on acidic, neutral and alkaline cadmium polluted soil, reduce the effective cadmium content of the soil, inhibit the cadmium absorption of crops, improve the organic matter content of the soil, improve the soil structure, have the effects of fertility betterment and yield increase, and achieve the effect of integrating the repairing and fertility betterment. Meanwhile, the soil remediation agent has the advantages of environmental friendliness, simple formula, low addition amount, high passivation effect, no influence on agricultural production and simplicity in preparation.

Description

soil remediation agent, preparation method and application thereof, and soil remediation method

Technical Field

the invention relates to the technical field of soil remediation, in particular to a soil remediation agent, a preparation method and an application thereof, and a soil remediation method.

Background

due to the reasons of atmospheric settlement, application of pesticides containing lead, mercury, copper, arsenic and the like, unreasonable application of chemical fertilizers, sewage irrigation and the like, the problem of heavy metal pollution of agricultural land in China is increasingly prominent, the yield of grains is reduced by over 100 million tons due to heavy metal pollution every year, the amount of grains polluted by heavy metal exceeds 1200 million tons, and the economic loss is huge; and methyl compounds with stronger toxicity can be generated through food chain enrichment and enter human bodies, so that the health of the human bodies is harmed. According to survey bulletin of national soil pollution conditions issued by the environmental protection department and the national soil resources department in 2014, the exceeding rate of the soil point of farmland in China is 19.4%, and the pollution is most prominent in heavy metal pollution such as Cd, Ni and Cu. According to statistics, the concentration of cadmium in northern provinces is generally lower than that in southern provinces, and the main reason is that most southern provinces have a large amount of non-ferrous metal reserves. The average cultivated land of China is less than half of the average level of the world, and how to solve the problem of soil pollution, particularly heavy metal pollution of large-area farmland soil, is a very serious and troublesome problem. For the soil pollution condition, the state also continuously issues laws and regulations, and the development of the soil remediation work is further promoted by the formal implementation of soil pollution prevention and control law in 1 month and 1 day in 2019.

Cadmium is mainly water-soluble in soil (Cd)²⁺、CdCl⁺、CdSO₄Etc.) and water-insoluble (CdS, CdCO)₃、Cd₃(PO₄)₂Etc.) exist, and the existing state of the fertilizer is also changed under the influence of factors such as soil pH, oxidation-reduction potential, organic matter content and the like. In soil, the toxicity of heavy metals to plants and the absorption of heavy metals by plants depend mainly on the occurrence of the heavy metals in the soil, especially the biologically available state, which is the state actually absorbed by the plants. Therefore, compared with the full amount of heavy metals, the effective state of the cadmium-polluted soil in the farmland can better reflect the possibility that plants absorb and are polluted by the heavy metals in the soil, and the cadmium-polluted soil has more practical significance. At present, the farmland heavy metal polluted soil remediation technologies mainly comprise physical and chemical technologies (including soil replacement, leaching technology, electric remediation technology and the like), biological remediation technologies (microbial remediation, plant remediation and the like)) And agricultural regulation and control technologies (passivant addition, water and fertilizer management, planting structure adjustment and the like) and the like. Compared with the physical and chemical engineering technology, the agricultural heavy metal pollution agricultural regulation and control measures for the farmland have relatively less investment and simpler and more convenient operation, basically do not change the planting habit of the restoration area, can fully exert the self-restoration capability of the ecological system, and are relatively in line with the national conditions of China.

The agricultural regulation measures comprise measures of regulating water and fertilizer, applying modifiers and the like, and a plurality of soil improvement products comprise fertility enhancers, passivators, regulators and the like, such as organic fertilizers, lime, biochar and the like. The soil conditioner has different types and different action mechanisms, and mainly improves the physical properties of soil such as water content, volume weight and the like, and changes the chemical properties of soil such as pH, organic matters and the like, so that the biological effectiveness of heavy metals in the soil is reduced by changing the adsorption, precipitation, complexation, oxidation reduction and the like of the soil to the heavy metals, and finally the safe utilization of the polluted agricultural land is realized.

Patent CN 108865157A discloses a repairing agent and a repairing method for heavy metal contaminated soil, wherein the agent comprises A and B, and the A comprises aggregate, portland cement clinker, lime and gypsum; the medicament B comprises biochar, livestock and poultry manure, agricultural waste residues or waste materials, calcium dihydrogen phosphate and sodium alginate. The medicine has complicated components and brings inconvenience to the operation. Patent CN 108219794A discloses a medicament for restoring cadmium-polluted soil of farmland in northern wheat planting areas, which mainly comprises desulfurized gypsum, ferric oxide and attapulgite, and the dosage of the medicament is 40-60 g/kg. Firstly, the passivator only aims at the repair of northern wheat planting farmland and has limitation; secondly, the adding amount is higher, which easily causes larger influence on the farmland soil structure and increases the repair cost. Patent CN 109369285A discloses a conditioner for heavy metal cadmium pollution of medium-alkaline soil and application thereof, wherein the conditioner comprises a calcium magnesium phosphate fertilizer, a lime sulfur mixture and biochar, but the conditioner is also used for heavy metal cadmium polluted soil with the pH value not less than 7 and has great limitation; secondly, the three materials are alkaline and have great influence on the pH value of the soil.

in general, the existing passivators for restoring cadmium-polluted farmland soil have certain limitations, such as limited use area, single crop, large addition amount, high cost, complex process, soil structure destruction and the like. Therefore, there is a need to develop a cadmium pollution remediation agent which is efficient, simple, wide in application range and friendly to the farmland soil environment.

In view of this, the invention is particularly proposed.

Disclosure of Invention

the invention aims to provide a soil remediation agent, a preparation method and application thereof as well as a soil remediation method.

The invention is realized by the following steps:

In a first aspect, the embodiment of the invention provides a soil remediation agent, which comprises 7-25 parts of acidic polymer, 18-45 parts of organic fertilizer and 30-75 parts of sulfide by weight.

In an alternative embodiment, the organic fertilizer comprises 10-25 parts of the acidic polymer, 20-40 parts of the organic fertilizer and 50-70 parts of the sulfide by weight;

Preferably, it comprises 15 parts of the acidic polymer, 25 parts of the organic fertilizer and 60 parts of the sulfide.

in an alternative embodiment, the acidic polymer is a metal salt polymer, preferably, the metal salt polymer is an iron salt polymer or an aluminum salt polymer, preferably, the iron salt polymer is polymeric iron sulfate, and the aluminum salt polymer is polymeric aluminum chloride.

In an alternative embodiment, the sulphide is technical grade sulphide, preferably the technical grade sulphide has a mass percentage of 45-65%, preferably 45%;

More preferably, the technical grade sulfide is selected from at least one of technical grade calcium polysulfide, sodium sulfide, sodium sulfite, or sodium thiosulfate;

Most preferably, the technical grade sulfide is 45% by mass of calcium polysulfide;

Preferably, the particle size of the sulphide is between 0.5 and 2 millimetres, more preferably 2 millimetres.

In alternative embodiments, the organic fertilizer is fermented animal manure;

preferably, the organic fertilizer is at least one of fermented pig manure, fermented chicken manure and fermented cow manure;

More preferably, the particle size of the organic fertilizer is 0.5-2 mm, preferably 2 mm.

In a second aspect, embodiments of the present invention provide a method of preparing a soil remediation agent according to any one of the preceding embodiments, comprising: and mixing an acidic polymer, an organic fertilizer and a sulfide to form the soil remediation agent.

In an alternative embodiment, the preparation of the organic fertilizer comprises: fermenting the animal waste;

preferably, the fermentation treatment comprises: animal waste is sequentially sterilized, deinsectized and decomposed and fermented at the temperature of 45-70 ℃.

In an alternative embodiment, mixing further comprises milling;

Preferably, the acidic polymer, the organic fertilizer and the sulfide are separately ground;

Preferably, the mixing is followed by sieving;

more preferably, the sieving is through a 0.5-2 mm sieve, preferably a 2mm sieve.

In a third aspect, the present invention provides the use of the soil remediation agent or the soil remediation agent prepared by the method according to any one of the preceding embodiments in remediation of heavy metal contaminated soil, preferably, the heavy metal contamination is cadmium contamination.

In a fourth aspect, an embodiment of the present invention provides a method for soil remediation, including: applying the soil remediation agent of any one of the preceding embodiments or prepared by the preparation method of any one of the preceding embodiments to contaminated soil;

Preferably, the application amount of the soil remediation agent accounts for 0.3-1.5% of the mass of the contaminated soil, and is preferably 0.5%;

preferably, the application of the soil remediation agent further comprises: turning, watering and maintaining;

More preferably, the conditions of plowing are: ploughing for 1-2 times, wherein the ploughing depth is 20-30 cm;

Preferably, the amount of water added is 25-35%, preferably 30%, of the dry basis weight of the soil;

More preferably, the curing conditions are: and (4) keeping away from light, and sealing for 7-10 days.

The invention has the following beneficial effects: according to the invention, the acidic polymer, the organic fertilizer and the sulfide are adopted and the use proportion of the organic fertilizer and the sulfide is controlled, so that the three generate a synergistic effect, the soil polluted by acidic, neutral and alkaline cadmium can be well repaired, the effective cadmium content of the soil is reduced, the cadmium absorption of crops is inhibited, the organic matter content of the soil can be increased, the soil structure is improved, the effects of fertility improvement and yield increase are achieved, and the effect of integrating restoration and fertility improvement is achieved. Meanwhile, the soil remediation agent has the advantages of environmental friendliness, simple formula, low addition amount, high passivation effect, no influence on agricultural production and simplicity in preparation. The repairing method of the invention is in-situ repairing, does not affect agricultural production, and has low cost, simple process and high repairing effect.

Detailed Description

in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The features and properties of the present invention are described in further detail below with reference to examples.

the embodiment of the invention provides a soil remediation agent which comprises, by weight, 7-25 parts of an acidic polymer, 18-45 parts of an organic fertilizer and 30-75 parts of sulfide. Preferably, the fertilizer comprises 10-25 parts of the acidic polymer, 20-40 parts of the organic fertilizer and 50-70 parts of the sulfide; preferably, it comprises 15 parts of the acidic polymer, 25 parts of the organic fertilizer and 60 parts of the sulfide.

By using and controlling the proportion of the acidic polymer, the organic fertilizer and the sulfide, the synergistic effect of the acidic polymer, the organic fertilizer and the sulfide can be ensured, the cadmium-polluted soil with acidic (pH <6.5), alkaline (pH >7.5) or neutral (pH6.5-7.5) has a good repairing effect, the soil repairing agent can reduce the content of effective cadmium in the soil, inhibit the cadmium absorption of crops, simultaneously improve the content of organic matters in the soil, improve the soil structure, have the functions of fertilizing and increasing the yield, realize the integration of repairing and fertilizing, and the passivating effect which can be achieved by the invention can not be achieved by singly adopting any one of the substances.

Specifically, the acidic polymer can adjust the pH value of the soil, avoid the obvious increase of the pH value of the soil, and simultaneously provide a large amount of macromolecular complexes, so that the acidic polymer has a good adsorption effect on cadmium and can reduce the content of effective cadmium. The organic fertilizer contains various organic acids, peptides and the like, and a large amount of Na is contained on the surface of the organic fertilizer⁺、Ca²⁺、Mg²⁺、HCO^3-and Cl^-the plasma and the functional group can adsorb and fix cadmium after being applied, reduce the absorption of cadmium by crops, adjust the pH value of soil, enrich organic matters of the soil and improve the fertility of the soil. The sulfide is alkaline, after the cadmium sulfide is applied to soil, on one hand, the pH value of the soil is improved, and the bioavailability of cadmium is reduced, on the other hand, the heavy metal cadmium and the sulfide can form cadmium sulfide precipitate, and the absorption of cadmium by crops is reduced.

further, the acidic polymer is a metal salt polymer, preferably, the metal salt polymer is an iron salt polymer or an aluminum salt polymer, preferably, the iron salt polymer is polymeric ferric sulfate, and the aluminum salt polymer is polymeric aluminum chloride; more preferably, the mass percent of iron in the polymeric ferric sulfate is 22-25%.

Preferably, polymeric ferric sulfate which is acidic is adopted to jointly adjust the pH value of the soil, so that the pH value of the soil is prevented from being obviously increased; meanwhile, the fertilizer can provide iron elements required by crop growth after being applied to soil; in addition, the polymeric ferric sulfate can provide a large amount of macromolecular complexes and hydrophobic hydroxide polymers, has a good adsorption effect on cadmium, enables the soil repairing agent to have the effects of repairing and fertilizing, is cheap and easy to obtain, and can reduce the production cost.

the adopted acidic ferric sulfate is also industrial polymeric ferric sulfate, wherein the mass percent of iron is 22-25%.

Further, the sulfide is industrial-grade sulfide, preferably, the mass percent of the industrial-grade sulfide is 45-65%, preferably 45%;

Preferably, the sulfide is adopted, so that the interaction of the acidic polymer and the organic fertilizer can be better, the effective cadmium content of the soil can be reduced, and the passivation effect can be improved.

further, the organic fertilizer is fermented animal manure;

More preferably, the organic fertilizer is granular;

the fermented animal manure needs to be subjected to conventional operations such as granulation, so that the final organic fertilizer is granular, the particle size of the organic fertilizer needs to be controlled, and the organic fertilizer can exert the effect of the organic fertilizer conveniently.

furthermore, the organic fertilizer can be further ensured to generate a synergistic effect with the acidic polymer and the sulfide, so that the organic matter content of the soil is improved, the soil structure is improved, and the repairing and fertilizing effects of the soil repairing agent are realized.

The invention also provides a preparation method of the soil remediation agent, which comprises the following steps: and mixing an acidic polymer, an organic fertilizer and a sulfide to form the soil remediation agent.

Specifically, animal wastes are fermented;

The method for fermenting the animal wastes ensures that nutrient components in the obtained organic fertilizer are more easily absorbed by soil, enriches soil organic matters and improves soil fertility. Meanwhile, the cadmium is favorably adsorbed and fixed, and the absorption of cadmium by crops is reduced.

and then grinding, wherein the acidic polymer, the organic fertilizer and the sulfide are respectively and independently ground, so that the particle size of each raw material is 0.5-2 mm, preferably 2 mm.

And then mixing the acidic polymer, the organic fertilizer and the sulfide according to a ratio, and sieving after mixing, wherein the sieving is carried out by a sieve of 0.5-2 mm, preferably a sieve of 2 mm. The particle size of the soil repairing agent is controlled by screening, which is more beneficial to the soil repairing agent to exert the effect.

The acidic polymer, the sulfide and the organic fertilizer can be mixed when needed or can be mixed in advance.

The invention also provides a soil remediation method, comprising: the soil remediation agent or the soil remediation agent prepared by the preparation method is applied to polluted soil.

the amount of the soil remediation agent applied is 0.3 to 1.5%, for example, 0.3%, 0.5%, 0.7%, 1%, 1.5%, etc., based on the mass of the contaminated soil, but is not limited to the above-mentioned values, and may be any value within the range, preferably 0.5%.

Preferably, the amount of water added is 25-35%, preferably 30%, of the dry basis weight of the soil; namely, the water content is 25 to 30 percent, and the water content is preferably 30 percent;

more preferably, the curing conditions are: and (4) keeping away from light, and sealing for 7-10 days. By adopting the repairing method, the repairing effect can be further improved, and in-situ repairing is adopted, so that the agricultural production is not influenced, the cost is low, the process is simple, and the repairing effect is high.

specifically, the soil remediation agent is uniformly spread on the soil surface before the crops are planted, mechanically ploughed to be uniformly mixed with the soil plough layer, then sprayed with water, and maintained for one week. And then collecting a soil sample after maintenance, and measuring the content of the effective cadmium.

Wherein, the collection of the soil sample is carried out and processed according to the requirements in the technical provisions of agricultural soil sample collection, circulation preparation and preservation. The content of cadmium in an available state of soil is determined according to the method steps in determination of content of elements in an available state in soil 8 (HJ 804-2016).

example 1

The embodiment provides a soil remediation agent, which comprises 7 parts of polymeric ferric sulfate, 45 parts of organic fertilizer and 30 parts of sulfide; wherein the polyferric sulfate is of industrial grade and has a mass fraction of 22%; the organic fertilizer is fermented chicken manure with the grain size of 2 mm; the sulfide is industrial sodium sulfide, the mass fraction is 65%, and the particle size is 2 mm.

The embodiment also provides a preparation method for soil remediation, which comprises the following steps:

Fermentation treatment: sequentially carrying out sterilization, deinsectization and decomposition fermentation treatment at 70 ℃.

And then grinding is carried out, so that the particle sizes of the polymeric ferric sulfate, the fermented chicken manure and the sodium sulfide are all 2 mm.

Then mixing the three, sieving the mixture through a 2mm sieve.

Example 2

The embodiment provides a soil remediation agent, which comprises 25 parts of polymeric ferric sulfate, 45 parts of organic fertilizer and 75 parts of sulfide; wherein the polyferric sulfate is in industrial grade, and the mass fraction is 25%; the organic fertilizer is fermented chicken manure with the grain size of 1 mm; the sulfide is industrial-grade calcium polysulfide with the mass fraction of 45 percent and the particle size of 1 mm.

The preparation method is the same as example 1, except that the fermentation temperature is 45 ℃ and the fermentation is carried out by passing through a sieve with the particle size of 1 mm.

Example 3

The embodiment provides a soil remediation agent, which comprises 20 parts of polyaluminium chloride, 40 parts of organic fertilizer and 50 parts of sulfide; wherein the polyaluminium chloride is industrial grade and has a mass fraction of 35%; the organic fertilizer is fermented chicken manure with the grain size of 0.5 mm; the sulfide is industrial sodium sulfide, the mass fraction is 65%, and the particle size is 0.5 mm.

The preparation method is the same as example 1 except that the fermentation temperature is 50 ℃ and the sieved particle size is 0.5 mm.

Example 4

the embodiment provides a soil remediation agent, which comprises 15 parts of polymeric ferric sulfate, 25 parts of organic fertilizer and 60 parts of sulfide; wherein the polyferric sulfate is in industrial grade, and the mass fraction is 25%; the organic fertilizer is fermented chicken manure with the grain size of 2 mm; the sulfide is industrial-grade calcium polysulfide with the mass fraction of 45 percent and the particle size of 2 mm.

The preparation method is the same as example 1, except that the fermentation temperature is 60 ℃ and the sieved particle size is 2 mm.

Example 5

the embodiment provides a soil remediation agent, which comprises 15 parts of polyaluminium chloride, 20 parts of organic fertilizer and 65 parts of sulfide; wherein the polyaluminum chloride is industrial grade; the organic fertilizer is fermented chicken manure with the grain size of 0.5 mm; the sulfide is industrial sodium sulfide, the mass fraction is 65%, and the particle size is 0.5 mm.

the preparation method is the same as example 1, except that the fermentation temperature is 65 ℃ and the sieved particle size is 0.5 mm.

Example 6

the embodiment provides a soil remediation agent, which comprises 10 parts of polymeric ferric sulfate, 30 parts of organic fertilizer and 60 parts of sulfide; wherein the polyferric sulfate is of industrial grade and has a mass fraction of 23%; the organic fertilizer is fermented chicken manure with the grain size of 0.5 mm; the sulfide is industrial-grade calcium polysulfide with the mass fraction of 45 percent and the particle size of 0.5 mm.

Example 7

the embodiment provides a soil remediation agent, which comprises 15 parts of polymeric ferric sulfate, 30 parts of organic fertilizer and 55 parts of sulfide; wherein the polyferric sulfate is of industrial grade and has a mass fraction of 22%; the organic fertilizer is fermented chicken manure with the grain size of 0.5 mm; the sulfide is industrial sodium sulfide, the mass fraction is 65%, and the particle size is 0.5 mm.

the preparation method is the same as example 1 except that the fermentation temperature is 58 ℃ and the sieved particle size is 0.5 mm.

Comparative example 1: a soil conditioner was prepared by referring to the preparation method of example 4, except that the soil conditioner of comparative example 1 contained only industrial-grade polymeric ferric sulfate in a mass fraction of 25%.

Comparative example 2: a soil remediation agent was prepared according to the manufacturing method of example 4, except that the soil remediation agent of comparative example 2 included 25 parts of chicken manure and 75 parts of calcium polysulfide.

Comparative example 3: a soil remediation agent was prepared by reference to the manufacturing process of example 4, except that the soil remediation agent of comparative example 3 included 15 parts of polymeric ferric sulfate and 85 parts of calcium polysulfide.

Comparative example 4: a soil remediation agent was prepared according to the preparation method of example 4, except that the soil remediation agent of comparative example 4 included 15 parts of chicken manure, 25 parts of polymeric ferric sulfate, and 60 parts of calcium oxide.

experimental example 1

experimental site: the cadmium in the farmland polluted by some cadmium in Shijiazhuang Zhao county has the effective cadmium content of about 0.45mg/kg and the soil pH of about 6.8;

An experimental repairing agent: the soil remediation agent provided in example 4 and the soil remediation agents of comparative examples 1-4;

(1) dividing the polluted farmland into cells, wherein the area of each cell is 5m multiplied by 5m, randomly selecting the cells, independently adding 0.3%, 0.5% and 1% of the soil remediation agent provided in the embodiment 4 into the selected cells, mechanically ploughing twice with the depth of 20cm to fully and uniformly mix the soil with plough layer soil, and sprinkling water to adjust the water content of the soil to 30%. And maintaining for 7 days. And (4) measuring the content of the available state cadmium in the repaired soil by adopting a method of measuring the content of the available state elements in the soil 8 (HJ 804-2016). The soil background information and the remediation results are shown in table 1.

Table 1 example 4 soil remediation test results

As can be seen from the results shown in Table 1, the addition amount of the soil remediation agent is 0.3% -1%, the effective cadmium content is reduced from 0.453mg/kg to 0.130mg/kg and is reduced by 71.3%, and the pH value of the soil is increased before and after treatment, but is within the range of 6-9.

(2) Randomly selecting cells, respectively and independently adding 0.5% of the soil remediation agent provided in the example 4 and the comparative examples 1-4 into the selected cells, mechanically ploughing twice with the depth of 20cm to fully and uniformly mix the soil remediation agent with the plough layer soil, and watering to adjust the water content of the soil to 30%. And maintaining for 7 days. And measuring the content (mg/kg) of the effective state cadmium in the repaired soil by adopting a method of measuring the content of the effective state elements in the soil 8 (HJ 804-2016). The soil background information and the remediation results are shown in table 2.

TABLE 2

As shown in the table 2, the soil remediation agent can greatly reduce the content of effective cadmium in soil and meet the requirement that the pH value of farmland soil is kept within the range of 6-9. The polymeric ferric sulfate, the organic fertilizer and the sulfide in the soil remediation agent simultaneously act, so that the best remediation effect is achieved. The reduction rate of the effective cadmium content of farmland soil or the pH value of soil can be greatly influenced by single component or lack of any one of the components or change of the content of each substance in the components. The components of the repairing material are harmless to soil and crops, and the repairing material has the effects of passivation, fertility improvement and yield increase.

Experimental example 2

Experimental site: in a garden polluted by some cadmium in Yunnan, the content of the effective cadmium is about 0.2mg/kg, and the pH value of soil is about 5.5;

an experimental repairing agent: the soil remediation agent provided in example 5;

The method comprises the following steps: dividing a polluted farmland into cells, wherein the area of each cell is 5m multiplied by 5m, randomly selecting the cells, independently adding 0.3%, 0.5% and 1% of the soil remediation agent provided in the embodiment 5 into each selected cell, mechanically ploughing twice with the depth of 30cm to fully and uniformly mix the soil remediation agent with plough layer soil, and watering to adjust the water content of the soil to 25%. Maintaining for 10 days. And measuring the content (mg/kg) of the effective state cadmium in the repaired soil by adopting a method of measuring the content of the effective state elements in the soil 8 (HJ 804-2016). The soil background information and the remediation results are shown in table 3.

table 3 example 5 soil remediation test results

as can be seen from Table 3, the addition amount of the soil remediation agent is 0.3% -1%, the effective cadmium content is reduced from 0.233mg/kg to 0.059mg/kg and is reduced by 74.7%, and the pH value of the soil is slightly increased and is not greatly changed before and after treatment, and the pH value is within the range of 6-9.

experimental example 3

experimental site: in a farmland polluted by certain Tianjin cadmium, the content of effective cadmium is about 0.2mg/kg, and the pH of soil is about 7.8;

An experimental repairing agent: the soil remediation agent provided in example 6;

The method comprises the following steps: dividing the polluted farmland into cells, wherein the area of each cell is 5m multiplied by 5m, randomly selecting the cells, independently adding 0.3%, 0.5% and 1% of the soil remediation agent provided in the embodiment 6 into each selected cell, mechanically ploughing twice with the depth of 25cm to fully and uniformly mix the soil with plough layer soil, and sprinkling water to adjust the water content of the soil to 35%. And maintaining for 8 days. And measuring the content (mg/kg) of the effective state cadmium in the repaired soil by adopting a method of measuring the content of the effective state elements in the soil 8 (HJ 804-2016). The soil background information and the remediation results are shown in table 4.

Table 4 example 6 soil remediation test results

As can be seen from Table 4, the addition amount of the repair material is 0.3% -1%, the content of cadmium in an effective state is reduced from 0.23mg/kg to 0.106mg/kg, the content is reduced by 53.9%, and the pH value of the soil before and after treatment is increased, but is within the range of 6-9.

the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The soil remediation agent is characterized by comprising 7-25 parts by weight of acidic polymer, 18-45 parts by weight of organic fertilizer and 30-75 parts by weight of sulfide.

2. The soil remediation agent of claim 1 including, in parts by weight, 10 to 25 parts of said acidic polymer, 20 to 40 parts of said organic fertilizer, and 50 to 70 parts of said sulfide;

3. the soil remediation agent of claim 1 or 2 wherein said acidic polymer is a metal salt polymer, preferably said metal salt polymer is at least one of a ferric salt polymer and an aluminum salt polymer, preferably said ferric salt polymer is polymeric ferric sulfate and said aluminum salt polymer is polymeric aluminum chloride;

More preferably, the polymeric ferric sulfate is industrial grade polymeric ferric sulfate;

more preferably, the mass percent of iron in the industrial grade polymeric ferric sulfate is 22-25%.

4. The soil remediation agent of claim 1 or 2, wherein said sulfide is technical grade sulfide, preferably 45-65%, preferably 45% by weight;

5. The soil remediation agent of claim 1 or 2 wherein said organic fertilizer is fermented animal manure;

more preferably, the organic fertilizer is granular,

6. The method of preparing a soil remediation agent of any one of claims 1 to 5 including: and mixing an acidic polymer, an organic fertilizer and a sulfide to form the soil remediation agent.

7. The method according to claim 6, wherein the preparation of the organic fertilizer comprises: fermenting the animal waste;

8. The method of claim 6, further comprising grinding prior to mixing;

Preferably, the mixing is followed by sieving,

9. Use of the soil remediation agent of any one of claims 1 to 5 or prepared by the method of any one of claims 6 to 8 for remediation of heavy metal contaminated soil, preferably, the heavy metal contamination is cadmium contamination.

10. a method of soil remediation, comprising: applying the soil remediation agent of any one of claims 1-5 or prepared by the method of any one of claims 6-8 to contaminated soil;