CN110591724A - Conditioner for treating heavy metal contaminated soil and preparation method and application thereof - Google Patents
Conditioner for treating heavy metal contaminated soil and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to a conditioner for treating heavy metal contaminated soil, which comprises a silicate source, biomass charcoal, fly ash, urea and microbial strains; the mass ratio of the silicate source to the biomass carbon to the fly ash to the urea to the microbial strain is (1-3): (1-7): (1-5): (1-2): (1-4) the invention also provides a preparation method of the conditioner for treating the heavy metal contaminated soil, and the invention utilizes the composition of the components, can obviously improve the treatment of the heavy metal contaminated soil, obviously reduce the content of heavy metals such as cadmium and the like, and improve the yield and the quality of crops.
Description
Technical Field
The invention relates to a conditioner for treating heavy metal polluted soil such as cadmium and the like, and a preparation method and application thereof, belonging to the field of heavy metal polluted soil treatment.
Background
In recent years, the heavy metal pollution in China presents an aggravating situation, and the heavy metal pollution in soil poses serious threats to the ecological environment, food safety and human health. On 18 th 4 th month in 2014, the survey bulletin issued by the ministry of environmental protection and the ministry of homeland resources shows that the national soil environment condition is totally optimistic, the soil pollution in some regions is serious, the soil environment quality of cultivated land is great, and the soil environment problem of industrial and mining waste land is prominent. According to incomplete statistics, the farmland with nearly 2000 kilohm 2 in China at present has pollution of different degrees, which occupies 1/5 of the farmland area, and the direct economic loss caused by the heavy metal pollution reaches 1200 kilotons every year, and exceeds 200 hundred million yuan.
The remediation technologies for heavy metal contaminated soil can be divided into two major categories, namely, physical and chemical remediation technologies and biological remediation technologies. The physical and chemical repair techniques can be classified into an isolation embedding technique, a curing and stabilizing technique, a chemical agent stabilizing technique, an electric repair technique, and the like. The bioremediation technology can be further classified into a microbial remediation technology, a plant remediation technology, and the like. At present, the remediation of cadmium and arsenic polluted soil mainly focuses on a chemical agent stabilization method. The method has the characteristics of low cost, high repair efficiency, simple operation and the like. This technology was first studied and applied in some industrially developed countries, and has rapidly developed in the last decade.
Agents commonly used in chemical stabilization include organic and inorganic chelating agents. The chelating ability of the organic chelating agent to heavy metals is far higher than that of the inorganic chelating agent, the molecules of the organic chelating agent and the heavy metals are subjected to rapid chelating reaction to generate stable heavy metal complexes which are firmly embedded in a soil structure body, and the heavy metal complexes have strong acid-resistant leaching ability. Inorganic chelating agents such as phosphate are mostly applied to the existing stabilization treatment of cadmium and arsenic polluted soil. The method has the advantages that after phosphate is added into the cadmium and lead polluted soil, insoluble phosphoric acid precipitates can be formed, the water solubility of the precipitates is extremely low, so that the effective cadmium and arsenic in the soil can be effectively reduced, the defects are that the solubility is limited, the precipitates cannot fully react with heavy metals in the soil, the medicament utilization rate is low, the medicament is increased and wasted, and the heavy metals are easily leached again due to the change of the environment.
CN201410672066 mentions that the stabilization treatment of the heavy metal contaminated soil by independently adding the phosphate solution is not only low in efficiency, but also long in consumption period.
Chinese patent publication No. 102657926a discloses a heavy metal normal temperature curing agent and a method for curing heavy metals in heavy metal pollutants by using the same. Wherein the heavy metal phosphate formed after solidification exists in the form of insoluble or slightly soluble compound, and heavy metal ions are easy to dissolve reversely after the pH value condition is changed. In addition to organic and inorganic chelating agent stabilization methods, there are also some methods of remediation for heavy metal contaminated soils.
Chinese patent document with publication number CN 103484125A discloses a method for improving heavy metal lead-polluted soil by using solid bamboo shoot shell based biochar as a soil conditioner. The improvement method is beneficial to improving the acidity of the soil and improving the adsorption quantity of cadmium and arsenic ions, but can not ensure that the leaching concentration of the cadmium and arsenic in the soil reaches the standard that the concentration of the cadmium and arsenic is lower than 0.25mg/L specified in the control standard of household garbage landfill pollutants. And the preparation process of the biochar needs drying, crushing and high-temperature pyrolysis at 400 ℃, the preparation process is complex, the energy consumption is large, and the biochar is not suitable for large-area severe lead-polluted soil or solid waste. In addition, due to the restriction of a chemical reaction equilibrium mechanism, single or multiple kinds of phosphate have limited stabilizing effect on heavily polluted heavy metal polluted soil, and the large-amount application can cause secondary pollution of the soil.
In conclusion, the current various cadmium and arsenic polluted soil stabilizers have the defects of poor effectiveness, low utilization rate, high cost and the like on the remediation of the heavily lead polluted soil.
Disclosure of Invention
In order to solve the problems of the existing conditioner, the invention provides a conditioner for treating heavy metal contaminated soil, aiming at improving the effectiveness of the conditioner on heavy metals and improving the treatment effect of the heavy metals.
The second purpose of the invention is to provide a preparation method of the conditioner.
The third purpose of the invention is to provide the application of the conditioning agent.
A conditioner for treating heavy metal contaminated soil comprises a silicate source, biomass charcoal, fly ash, urea and microbial strains.
Preferably, the mass ratio of the silicate source to the biomass charcoal to the fly ash to the urea to the microbial strain is (1-3): (1-7): (1-5): (1-2): (1-4).
Preferably, the mass ratio of the silicate source to the biomass charcoal to the fly ash to the urea to the microbial strain is 1: 5:3:2: 3.
preferably, the silicate source is a silicate compound and/or a silicate mineral; the silicate compound is at least one of sodium silicate, manganese silicate, iron silicate and nickel silicate; the silicate mineral is at least one of asbestos, mica, talc, kaolinite, montmorillonite and zeolite.
Preferably, the biomass charcoal is formed by carbonizing a biomass charcoal raw material, wherein the biomass charcoal raw material is at least one of peanut shells, coconut shreds, rice husks and straws.
Preferably, the microbial strain is ferrous oxide sulfate bacillus, and the effective strain number is more than or equal to 0.2 hundred million/g.
The invention also provides a preparation method of the conditioner for treating the heavy metal contaminated soil, which comprises the following steps:
1) preparing biomass charcoal:
cleaning a biomass raw material, drying to constant weight, crushing to powder, and sieving; weighing a certain amount of biomass charcoal raw material, putting the raw material into a tubular atmosphere furnace, performing programmed temperature rise at 300-500 ℃, performing anaerobic carbonization for 2-3h, and introducing carbon dioxide at the flow rate of 80-100ml/min into the tube as a reaction atmosphere; cooling to room temperature in the furnace to obtain biomass charcoal;
2) selecting a certain amount of silicate minerals, crushing and sieving;
3) according to the proportion of 1-3: 1-7: 1-5: 1-2: 1-4, respectively proportioning silicate minerals, biomass carbon, fly ash, urea and microbial strains;
4) stirring and spraying a certain amount of water for granulation;
5) and drying to obtain the conditioner.
The preparation method of the conditioner for treating heavy metal contaminated soil as claimed in any one of claims 1 to 6, wherein the preparation method comprises the following steps:
1) preparing silicate-containing modified biomass charcoal:
weighing a certain amount of sodium silicate to dissolve in a beaker, and preparing a sodium silicate solution according to a certain proportion; fully and uniformly mixing the dried, ground and sieved biomass carbon raw material and a sodium silicate solution according to a certain mass fraction, putting the mixture into a tubular atmosphere furnace, raising the temperature to a target temperature by adopting a program at the temperature of 300-500 ℃, then carrying out anaerobic carbonization for 4-7h, and introducing carbon dioxide into the tube at the flow rate of 80-120ml/min to serve as a reaction atmosphere; cooling to room temperature in a furnace to obtain silicate-containing modified biomass charcoal;
2) according to the following steps: 3:2: 0.5, respectively proportioning the silicate-containing modified biomass carbon, the fly ash, the urea and the microbial strains;
3) stirring and spraying a certain amount of water for granulation;
4) and drying to obtain the conditioner.
The invention also provides an application of the conditioner for treating the heavy metal contaminated soil, and the conditioner is applied to the soil to be treated.
Preferably, the soil is crop planting soil.
Compared with the prior art, the invention has the following effective effects:
1. according to the invention, a large number of researches show that the synergistic effect of the components is beneficial to improving the effectiveness of the conditioner on soil heavy metal, obviously improving the treatment effect of the heavy metal and obviously reducing the heavy metal content of the planted crops;
2. according to the invention, the conditioner is formed by combining and reacting a plurality of components, so that the heavy metal restoration rate is high, the efficiency is high, and the problem of low restoration capacity caused by adopting a single component in the prior art is solved;
3. the silicate-containing modified biomass carbon modified into nano-scale particles has special capturing capability for heavy metals, particularly cadmium, and a coating layer is formed around the heavy metal ions after capturing the heavy metals so as to isolate the heavy metals from the outside, thereby achieving the stabilizing effect,
4. In the invention, the biomass charcoal can be prepared by adopting the existing commercial materials and also by adopting the biomass charcoal raw material through carbonization, and has low material cost and wide practical range.
Drawings
FIG. 1 shows the dynamic change of the percentage of cadmium in each form under different treatments in example 3 of the present invention.
Detailed description of the invention
A conditioner for treating heavy metal contaminated soil comprises a silicate source, biomass charcoal, fly ash, urea and microbial strains. The mass ratio of the silicate source to the biomass carbon to the fly ash to the urea to the microbial strain is (1-3): (1-7): (1-5): (1-2): (1-4).
Preferably, the mass ratio of the silicate source to the biomass charcoal to the fly ash to the urea to the microbial strain is 1: 5:3:2: 3.
the silicate source is a silicate compound and/or a silicate mineral; the silicate source is island silicate, cyclic silicate, etc. The silicate compound is at least one of sodium silicate, manganese silicate, iron silicate and nickel silicate; the silicate mineral is at least one of asbestos, mica, talc, kaolinite, montmorillonite and zeolite. The existing minerals with silicate as the main component can be theoretically used as the silicate source of the invention. The biomass charcoal is formed by carbonizing a biomass charcoal raw material, wherein the biomass charcoal raw material is at least one of peanut shells, coconut shreds, rice husks and straws.
The microbial strain is ferrous oxide sulfate bacillus, and the effective strain number is more than or equal to 0.2 hundred million/g.
In the heavy metal treatment process, soil is firstly detected, including pollution factors, physical and chemical properties and the like; according to the detection result, the content of each component of the conditioner is adjusted, and after the conditioner is applied, the conditioner is uniformly sprayed to a farmland by equipment or manpower for ploughing and stirring.
The invention is particularly suitable for being used as soil for fixing heavy metal in a farmland, thereby obviously reducing the heavy metal content of planted crops.
The conditioner of the invention has the effect on heavy metals in soil,
the conditioner is preferably suitable for soil polluted by at least one heavy metal of cadmium, arsenic and lead. The research surface shows that the effect on the cadmium-polluted soil is better.
The conditioner is prepared by mixing silicate minerals, biomass carbon, fly ash and urea in proportion and adding microbial strains, wherein the silicate minerals have regular tetrahedron structures, and the regular tetrahedrons are connected in a chain, double-chain, sheet and three-dimensional frame mode, so that the treatment effect is improved.
In the conditioner, the cadmium content on the overground part of the plant can be reduced in the application process, the heavy metal resistance of the crop can be improved, no harmful substance is left in the soil, and no adverse effect is caused after long-term application.
In addition, the conditioner contains a large amount of water-soluble: SiO 22、Al2O3、FeO、Fe2O3、CaO、TiO2、MgO、K2O、Na2O、SO3、MnO2Etc., in addition to P2O5Essential nutrient elements for crops. Has good physical and chemical properties.
The conditioner is characterized in that the conditioner is matched with the microbial strains: the mineral substances, organic matters and various organisms of the soil are combined and acted with each other to make the soil have structure, particularly soil aggregates which are important factors of soil fertility, and microorganisms are not uniformly dispersed in the aggregates but form microcolonies and are closely connected with the soil aggregates.
(1) The invention also provides a preparation method I of the conditioner for treating the heavy metal contaminated soil, which comprises the following steps:
1) preparing biomass charcoal:
cleaning biomass raw materials, such as chaff, drying to constant weight, pulverizing into powder, and sieving with a 60-mesh sieve; weighing 20.00g of rice husk powder in a 50ml ceramic crucible, putting the rice husk powder into a tubular atmosphere furnace, raising the temperature to a target temperature by adopting a programmed temperature rise (10 ℃/min) at 300-500 ℃, then carrying out anaerobic carbonization for 2-3h, and introducing carbon dioxide into the tube at a flow rate of 80-100ml/min as a reaction atmosphere; cooling to room temperature in the furnace to obtain biomass charcoal; the pH value of the biochar is 9.8, and the ash content is 36.72%;
2) selecting a certain amount of silicate minerals, crushing, and sieving by a 60-mesh sieve; the silicate mineral is selected from kaolin;
3) according to the proportion of 1-3: 1-7: 1-5: 1-2: 1-4, respectively proportioning silicate minerals, biomass carbon, fly ash, urea and microbial strains; preferably, the proportion of 3:5:3:2:3 is carried out;
4) stirring uniformly and spraying a certain amount of water for granulation;
5) and drying to obtain the conditioner.
(2) When the silicate source is silicate compound, the silicate compound can be used to react with the biomass charcoal to prepare silicate-containing modified biomass charcoal, and the preparation method (II) for preparing the conditioner by using the silicate-containing modified biomass charcoal comprises the following steps:
1) preparing silicate-containing modified biomass charcoal:
weighing a certain amount of sodium silicate (Na)2SiO3·9H2O) is dissolved in a beaker to prepare 0.56mol/l sodium silicate solution; fully and uniformly mixing the dried, ground and sieved biomass charcoal raw materials such as straws and a sodium silicate solution according to a certain mass fraction, putting the mixture into a tubular atmosphere furnace, raising the temperature to a target temperature by adopting a programmed temperature rise (10 ℃/min) at 500 ℃, then carrying out anaerobic carbonization for 7 hours, and introducing carbon dioxide at the flow rate of 100ml/min into the tube to serve as a reaction atmosphere; cooling to room temperature in a furnace to obtain silicate-containing modified biomass charcoal; measuring the pH value of the biomass charcoal to be 10.4, adjusting the mass parts of the straw and the sodium silicate to control the mass ratio of the biomass charcoal to the silicon to be 5: 1
2) According to the following steps: 3:2: 0.5, respectively proportioning the silicate-containing modified biomass carbon, the fly ash, the urea and the microbial strains;
3) stirring and spraying a certain amount of water for granulation;
4) and drying to obtain the conditioner.
The conditioner for treating the heavy metal contaminated soil can be applied to the soil to be treated; the soil to be treated is crop planting soil.
In the implementation process, pollution investigation is firstly carried out on a pollution production place, a remediation plan is formulated according to the pollution investigation result, and meanwhile, a corresponding remediation medicament is prepared according to the pollution concentration and the pollution factors. Application is carried out at the place of origin where the repair is required. The implementation steps are as follows:
1. the conditioner is uniformly sprayed to the farmland manually or mechanically.
2. And (5) ploughing the farmland (the ploughing depth is 15cm-20cm) and irrigating.
3. Fully stirring and mixing.
4. And (5) planting crops.
The present invention is described in detail below with reference to three examples, which are illustrative and not intended to limit the scope of the present invention.
Example 1: pot culture test of soil conditioner on acidic soil pollution passivation effect
The soil to be tested is collected from 0-20cm plough layer soil polluted by heavy metal in a certain farmland of Hunan Tan, the soil type is the quaternary red soil, and the basic physicochemical properties of the soil are shown in Table 1. The potting test was performed in the web room of the front terrace of the environmental science building of the university of agriculture in Hunan. A total of 5 treatments were set: the addition amounts of the contaminated soil control (CK1) without the modifier, the soil conditioner prepared by the preparation method I, and the soil conditioner prepared by the preparation method II are 1% and 2%, respectively. Each treatment was set to 3 replicates. The specific operation is shown in Table 2.
The collected soil is naturally air-dried and then is sieved by a nylon sieve with the aperture of 0.83 mm. The culture pot is made of polyethylene, the inner diameters of the upper opening and the lower opening are 57 cm and 38cm respectively, the height of the culture pot is 50cm, and small holes with the diameter of 6cm are formed in the positions, 10cm away from the upper opening and 5cm away from the lower opening, of the barrel wall respectively, so that flooding is prevented, and drainage is facilitated. 50kg of soil is filled in each pot, soil conditioners are respectively added according to test treatment 7 days before mustard transplantation, then the mixture is uniformly mixed, a certain amount of base fertilizer (8.2 g of urea, 8.2g of calcium superphosphate and 3.3g of potassium sulfate, which are equivalent to the fertilizing amounts of 337.5, 337.5 and 127.5 kg. hm < -2 >) is basal applied, the mixture is uniformly mixed with the soil with the surface layer of 0-5 cm, and the mixture is flooded by 3-5 cm. 11 leaf mustard plants are planted in each pot, the proper water content in the pot is kept, and insect pest management is carried out. Randomly collecting 5 bags in each pot of the mustard in the maturation period As samples, pre-treating, and measuring Cd and As contents in organs or parts of the mustard and Cd and As contents in soil on a machine.
After collecting the samples, cleaning soil with tap water, dividing the samples into edible parts and non-edible parts, putting the samples into numbered envelopes according to the conventional agricultural production habit, putting the numbered envelopes into a drying oven at 103 ℃ for fixation for 1 hour, adjusting the temperature to 65 ℃ and drying to constant weight, weighing and recording the dry weight of the samples of each part, crushing the plant samples with a plant crusher, and putting the crushed plant samples into a sealed bag for storage for later use. The sample is subjected to wet digestion (Wannlifna et al, 2008) by mixed acid (HNO 3: HClO4 ═ 4: 1), the content of Cd in the sample is measured by ICP-OES (US PE8300) after constant volume, and the content of total As is measured by a hydride-nondispersive atomic fluorescence method (GB/T17135-1997). And (4) putting the digestion solution which cannot be measured in time into a freezer for refrigeration and preservation at 4 ℃.
TABLE 1 basic physicochemical Properties of the soil
TABLE 2 test treatment names and contents
As can be seen from Table 3, the application of the soil conditioner increased the pH of the soil by 0.3-0.8 units compared to the CK1 control; the soil conditioners in different types have obvious difference, and 2 the soil conditioners have the following effects in sequence: the soil conditioner II is more than the soil conditioner I; the influence of different application amounts on the pH value of the soil is different, when the application amount is 1 percent of the mass fraction, the pH value of the soil is improved by 0.3-0.6 unit, when the application amount is 2 percent of the mass fraction, the pH value of the soil is improved by 0.6-0.8, and the effect of increasing the pH value of the soil is stronger along with the increase of the application amount; 2, the soil conditioner can obviously reduce the content of Cd and As in the effective state of the soil, and the reduction rate is respectively 8.05-31.03% and 6.76-19.94%; the better the reduction effect of Cd and As in the effective state of the soil is along with the increase of the application amount of the soil conditioner; 2, the soil conditioner can obviously reduce the contents of total cadmium and total arsenic in mustard plants, the reduction rates are respectively 2.05-46.34% and 3.07-30.91%, and Cd and As are more enriched at the roots of the mustard and less transferred to the upper part.
TABLE 3 Experimental data
50kg of cadmium-polluted soil is collected in a certain farmland of Hunan Tan, mustard is planted in a laboratory, and through experimental comparison, the cadmium content of the overground part applied with the conditioner is reduced by 26.89%. Therefore, the conditioner of the invention can obviously reduce heavy metal pollution.
Example 2: influence of soil conditioner on absorption and accumulation of Cd in different growth periods of southern acidic paddy soil rice
The soil to be tested is the soil polluted by Cd and is located in the soil of a certain cadmium-polluted farmland in Changsha, the pH value of the soil is 6.12, the Cd content is 0.84mg/kg, and the effective Cd content is 0.35 mg/kg; by adopting a field plot experiment, the plot area is 30m2, different soil conditioners are applied under the condition of simulating the soil flooding of the rice field, the influence of the soil conditioners on the absorption and accumulation of cadmium in the cadmium-polluted soil is researched, the rule of the absorption and accumulation of cadmium in the rice in different growth periods is discussed, and the scientific basis is provided for repairing the cadmium-polluted soil by using the soil conditioners. The field plot experiment sets 3 groups of treatments: the application amount of the soil conditioner I and the soil conditioner II of the contaminated soil control (CK2) without the addition of the conditioner is 150 kg. And (3) accumulating heavy metal rice varieties (Zhongjiazao No. 17) in the selection degree, performing false base fertilizer 5 days before rice planting, and spreading a soil conditioner 7 days before transplanting. Collecting plant samples at the tillering stage, heading stage and mature stage of the rice respectively, and performing pretreatment and then loading on the rice to determine the Cd content in each organ or part of the rice. After a rice sample is collected, washing soil with tap water, dividing the soil into root, stem, leaf, ear, grain and other parts, placing the grain sample in outdoor sunlight for drying, placing other parts of the sample in numbered envelopes, placing the envelope in a drying oven at 103 ℃ for fixation for 1 hour, adjusting the temperature to 65 ℃ for drying to constant weight, weighing and recording the dry weight of each part of the sample, subdividing the dried grain into chaff and brown rice by a brown rice machine, crushing the plant sample by a plant crusher, and placing the crushed plant sample into a sealing bag for storage for later use. Rice samples are subjected to wet digestion (Wannlifna et al, 2008) by mixed acid (HNO 3: HClO4 ═ 4: 1), the Cd content of the rice samples is measured by ICP-OES (American PE8300) after constant volume, and digestion solutions which cannot be measured in time are placed in a freezer for refrigeration and preservation at 4 ℃.
TABLE 4 Cd content (mg. kg-1) in each part of early rice at different growth periods
TABLE 5 influence of different treatments on Cd content of early rice at mature period and rice yield (unit: mg. kg-1)
The time from transplanting to harvesting of Zhongjiazao No. 17 is 4-7 months in 2016, seedling transplanting is carried out in 26 days in 4 months, and rice in 10 days in 5 months belongs to the seedling stage; the rice enters a tillering stage in 5 months and 20 days, and the characteristic condition of the rice growth is normal; the rice plants begin to enter the heading stage 16 days before and after 6 months, so that the rice plants grow more flourishing and heading; the rice is ripe in 7 months and 15 days, the rice ears turn yellow and the seeds are full. Table 3 shows the dynamic change of Cd content in each part of the rice in different growth periods by adding the corn straw biochar.
As can be seen from Table 4, the content of Cd in each part of the rice has a large span in three key growth periods, particularly the accumulation of Cd in the root of the rice is extremely prominent, and the variation range is between 0.46 and 0.79 mg.kg < -1 >; the content of Cd in the rice stem sheath is 0.30-0.59 mg/kg-1; the content of Cd in the rice leaves is 0.21-0.37 mg/kg-1. The overall rule of the relationship of Cd content in each part of rice in three growth periods is as follows: root system is larger than stem and larger than leaf, the Cd content in each part of the rice is lower than the total Cd content in soil, and the Cd content in the root, stem and leaf of the rice is gradually increased along with the growth of the rice.
As can be seen from Table 5, the distribution relationship of Cd content at each part of early rice in the mature period is as follows: chaff is larger than brown rice; compared with CK2, the treatment measures can reduce the content of Cd in rice chaff and brown rice, the Cd reduction amplitude is 15.15% and 20.00%, and the Cd content in the brown rice reaches the Cd limit index content (0.2 mg. kg < -1 >) in the food pollutant limit (GB 2762-2012). Compared with CK2, the yield of rice can be increased by each treatment in the aspect of rice yield (based on the dry weight of the ear part in the mature period), and the yield of rice is increased by 13.16% -22.25%.
When the conditioner is applied to the soil of a cadmium-polluted farmland in Changsha, Hunan, the rice yield is improved by 6%, and the cadmium content of rice is reduced by 48.9%. The conditioner of the invention can obviously reduce heavy metal pollution and greatly improve rice yield.
EXAMPLE 3 Effect of soil conditioner on arsenic and cadmium forms in soil
The soil to be tested is 0-20cm of plough layer soil polluted by heavy metal and collected from the periphery of a certain smelting plant in the Xiaguan area of the plant continental province of Hunan province, the soil is quaternary red soil, the pH value of the soil is 5.16, the total amount of Cd is 170.69 mg.kg < -1 >, the total amount of As is 123.37 mg.kg < -1 >, the total amount of Pb is 478.16 mg.kg < -1 >, the total amount of Zn is 149.18 mg.kg < -1 >, the content of Cu is 27.06 mg.kg < -1 >, the contents of As and Cd in the soil exceed the secondary standard of national soil environment quality, the soil is arsenic-cadmium composite polluted soil, and the cadmium pollution is the most serious.
The test adopts a method of indoor culture of soil. 400g of a 20 mesh soil sample was weighed separately on a one hundredth scale and transferred to a 1000ml glass beaker and 4 treatments were set up: blank control CK3(T31) without soil conditioner, application amount of the microbial agent of the acidithiobacillus ferrooxidans at 20 ml/mu (T32), application amount of the straw biochar at 150 kg/mu (T33) and application amount of the soil conditioner II at 150 kg/mu (T34), repeating the treatment for three times, mixing the soil and the biochar, adding deionized water, adjusting the mixture to the soil water layer of about 20cm, culturing at room temperature of 25 ℃ for 120 days, and measuring pH, As and the pH of the mixture every 6 days
And the morphological content of Cd.
Fig. 1 shows that, after 120 days of culture, with the extension of the culture time, each treatment can reduce the content of weak acid extractable cadmium and oxidizable cadmium in soil and increase the content of reducible cadmium and residual cadmium in flooded environment, the content of weak acid extractable cadmium in the treatment groups of T31, T32, T33 and T34 is respectively reduced from 73.55% before flooding to 63.46%, 57.73%, 54.50% and 53.94%, and the reduction amplitudes are as follows: t34 > T33 > T32 > T31. As is clear from Table 5, arsenic contained in the soil is mainly O-As (46.92% to 67.74%),
the second is Fe-As (18.15% -35.35%), then Al-As (6.91% -8.02%), Ca-As (6.68% -8.86%), and AE-As (0.03% -1.80%). With the increase of the culture time, the content of AE-As, Fe-As, Al-As and Ca-As gradually increased, and the content of O-As decreased, all showed significant differences (Table 4), compared with CK3 treatment, the increase range of the content of arsenic in exchange state, Fe-bound state and Ca-bound state was the largest for T34 treatment group, and the increase range was the lowest for T32 treatment group after T33 treatment group. The water flooding and the application of the corn straw biochar can reduce the content of arsenic in a residue state, but the treatment effect of each treatment group has no obvious difference. Compared with the common conditioner, the soil heavy metal conditioner prepared by the technology can be applied to the composite heavy metal pollution treatment of the soil of the acidic and neutral rice fields, can realize the efficient passivation of the composite pollution of the As and the Cd in the soil and reduce the absorption of the heavy metal Cd by the rice.
TABLE 6 arsenic dynamic changes in various forms (mg. kg-1) under different treatments
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A conditioner for treating heavy metal contaminated soil is characterized by comprising a silicate source, biomass charcoal, fly ash, urea and microbial strains.
2. The conditioner for treating heavy metal contaminated soil according to claim 1, wherein the silicate source, the biomass charcoal, the fly ash, the urea and the microbial strain are mixed in a mass ratio of (1-3): (1-7): (1-5): (1-2): (1-4).
3. The conditioner for treating soil polluted by heavy metal as claimed in claim 2, wherein the mass ratio of the silicate source, the biomass charcoal, the fly ash, the urea and the microbial strain is 1: 5:3:2: 3.
4. the conditioner for treating soil contaminated with heavy metals according to claim 1, wherein said silicate source is a silicate compound and/or a silicate mineral; the silicate compound is at least one of sodium silicate, manganese silicate, iron silicate and nickel silicate; the silicate mineral is at least one of asbestos, mica, talc, kaolinite, montmorillonite and zeolite.
5. The conditioner for remediating heavy metal contaminated soil as claimed in claim 1, wherein the biomass charcoal is formed by carbonizing a biomass charcoal raw material, wherein the biomass charcoal raw material is at least one of peanut shells, coconut shreds, rice husks and straws.
6. The conditioner for treating soil polluted by heavy metal as claimed in claim 1, wherein the microbial strain is ferrous sulfate bacillus, and the effective bacterial count is not less than 0.2 hundred million/g.
7. The preparation method of the conditioner for treating heavy metal contaminated soil according to any one of claims 1 to 6, wherein the preparation method comprises the following steps:
1) preparing biomass charcoal:
cleaning a biomass raw material, drying to constant weight, crushing to powder, and sieving; weighing a certain amount of biomass charcoal raw material, putting the raw material into a tubular atmosphere furnace, performing programmed temperature rise at 300-500 ℃, performing anaerobic carbonization for 2-3h, and introducing carbon dioxide at the flow rate of 80-100ml/min into the tube as a reaction atmosphere; cooling to room temperature in the furnace to obtain biomass charcoal;
2) selecting a certain amount of silicate minerals, crushing and sieving;
3) according to the proportion of 1-3: 1-7: 1-5: 1-2: 1-4, respectively proportioning silicate minerals, biomass carbon, fly ash, urea and microbial strains;
4) stirring and spraying a certain amount of water for granulation;
5) and drying to obtain the conditioner.
8. The preparation method of the conditioner for treating heavy metal contaminated soil according to any one of claims 1 to 6, wherein the preparation method comprises the following steps:
1) preparing silicate-containing modified biomass charcoal:
weighing a certain amount of sodium silicate to dissolve in a beaker, and preparing a sodium silicate solution according to a certain proportion; fully and uniformly mixing the dried, ground and sieved biomass carbon raw material and a sodium silicate solution according to a certain mass fraction, putting the mixture into a tubular atmosphere furnace, raising the temperature to a target temperature by adopting a program at the temperature of 300-500 ℃, then carrying out anaerobic carbonization for 4-7h, and introducing carbon dioxide into the tube at the flow rate of 80-120ml/min to serve as a reaction atmosphere; cooling to room temperature in a furnace to obtain silicate-containing modified biomass charcoal;
2) according to the following steps: 3:2: 0.5, respectively proportioning the silicate-containing modified biomass carbon, the fly ash, the urea and the microbial strains;
3) stirring and spraying a certain amount of water for granulation;
4) and drying to obtain the conditioner.
9. The use of the conditioner for controlling heavy metal contaminated soil according to any one of claims 1 to 6, wherein the conditioner is applied to the soil to be treated.
10. The use of a conditioner for the remediation of soil contaminated with heavy metals as claimed in claim 9 wherein said soil is crop plant soil.
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| CN114350375A (en) * | 2022-01-19 | 2022-04-15 | 山西省岩矿测试应用研究所(山西省贵金属及珠宝玉石检测中心) | Fly ash selenium-rich soil conditioner and preparation method and application thereof |
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| CN115090261A (en) * | 2022-05-23 | 2022-09-23 | 昆明理工大学 | Method for modifying biochar by using high-N earthworm liquid |
| CN115055508A (en) * | 2022-08-09 | 2022-09-16 | 中国科学院兰州化学物理研究所 | Preparation of soil remediation material and application of soil remediation material in remediation of soil of composite contaminated farmland |
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| CN115637151B (en) * | 2022-11-08 | 2024-04-30 | 中国农业大学 | Acid soil conditioner and preparation method thereof |
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