CN107052038B - Method for repairing arsenic-polluted soil by using microorganism-chemical method - Google Patents
Method for repairing arsenic-polluted soil by using microorganism-chemical method Download PDFInfo
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- CN107052038B CN107052038B CN201710338587.0A CN201710338587A CN107052038B CN 107052038 B CN107052038 B CN 107052038B CN 201710338587 A CN201710338587 A CN 201710338587A CN 107052038 B CN107052038 B CN 107052038B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/02—Extraction using liquids, e.g. washing, leaching, flotation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/10—Reclamation of contaminated soil microbiologically, biologically or by using enzymes
Abstract
The invention relates to a method for restoring arsenic-polluted soil by using a microorganism-chemical method, which comprises the steps of elution, adsorption, arsenic removal soil treatment and the like. The method of the invention is mainly characterized in that the solid-phase adsorption arsenic of the soil is reduced into trivalent arsenic by the microorganism strains with strong reduction capability on arsenic, and then the arsenic is promoted to enter the soil solution. The stabilizer EDTA is added to effectively shield the soil colloid, so that the secondary adsorption of arsenic in the soil solution and the soil colloid is prevented, and the aim of repairing the arsenic-polluted soil is finally achieved. The functional microorganism adopted in the invention is easy to culture and has strong arsenic reduction capability; the stabilizing agent and the fixing agent are nontoxic, and the fixing agent can be recycled for multiple times. By adopting the method, more than 31.3% of arsenic in the polluted soil with the total arsenic content of 30-80 mg/kg can be removed from the unearthed body.
Description
[ technical field ] A method for producing a semiconductor device
The invention belongs to the technical field of farmland maintenance. More particularly, the present invention relates to a method for remediating arsenic contaminated soil using a microbial-chemical process.
[ background of the invention ]
Arsenic is a toxic and carcinogenic metalloid element widely existing in nature, and the pollution problem of arsenic not only seriously affects the quality of agricultural products, but also seriously threatens the health of human beings, so that the arsenic pollution is a very serious environmental problem facing the world. China is a big country of arsenic mine and is one of the most seriously harmed countries by arsenic poisoning, the arsenic mine is widely distributed in provinces such as Hunan, Yunnan, Guangxi, Guangdong and the like in the middle and the southwest of China, and arsenic-containing waste emission brought by mining or smelting of the arsenic mine brings very serious influence on environmental safety; in addition, excessive investment of agricultural products such as arsenic-containing pesticides and fertilizers (mainly phosphate fertilizers and compound fertilizers) also causes the accumulation of arsenic in soil to a certain extent, and further influences the growth and development of plants and animals, and even the quality of agricultural products. Therefore, repairing arsenic-contaminated soil, reducing the effectiveness of arsenic crops in soil, and reducing the arsenic absorption of crops have become one of the important directions for agricultural environmental research.
At present, the remediation technology aiming at the arsenic-polluted soil mainly comprises hyperaccumulation phytoremediation, soil replacement by soil dressing, physical remediation and the like. The method mainly utilizes the arsenic hyper-enrichment capacity of crops, and finally removes the arsenic in the soil by a method of removing the crops. The physical remediation is mainly to cover or replace the original polluted soil with clean soil in a soil dressing or soil replacement mode, and the method has long remediation time, quick effect and high cost. In general, two repair technologies have a lot of problems in actual repair, which obviously limits the development and application popularization of the technology.
Arsenic in soil has various forms, but there is a great difference in mobility of arsenic in different forms. For example, trivalent arsenic has significantly higher mobility than pentavalent arsenic because the former is mostly in the zero valence state of H in meta-acid soils3AsO3Are present. Therefore, arsenic in soil can be reduced and converted into trivalent arsenic with stronger mobility, and then the arsenic is removed from soil body by a leaching method. At present, the elution technology of arsenic in soil is more studied and adopted by chemical methods, such as phosphate, EDTA, NTA, citric acid and the like. Although the eluting agents improve the arsenic eluting efficiency in the soil to a certain extent, the eluting agents affect the physical and chemical properties of the soil to a different extent and are easy to cause secondary pollution to the soil. From the aspect of the post-treatment process of the leacheate, the post-treatment difficulty is correspondingly increased, and the treatment cost is increased. In contrast, as a biotechnology which is relatively 'mild' and has no secondary pollution, the research of the microorganism in the field is relatively less, but the microorganism has a wide application prospect.
In recent years, many scientists have paid attention to research on environmental behavior of arsenic by microorganisms, and have tried to repair or control arsenic contamination in soil by using microorganisms having an oxidizing, reducing or methylating function to arsenic in the environment. For example, Pous et al, entitled "novel aproach to the biobased evolution of arsenic-polar group" J Hazard Mater, Vol 283, Vol 4, pp 617-622 (2015), describe that microorganisms with strong arsenic oxidation ability can convert trivalent arsenic in soil into pentavalent arsenic, thereby effectively reducing the toxicity of arsenic, increasing the adsorption of arsenic by soil colloids, and finally reducing the toxicity risk of arsenic in soil; chen et al, entitled "methylation of Arsenic from polar soil by Pseudomonas putida engineered for expression of the art M sensing (III) S-adenosine methyl transferase gene", Environmental Science & Technology, Vol.48, No. 17, p.10337-10344 (2014), describe the methylation of Arsenic by certain microorganisms, which can convert Arsenic into easily volatile Arsenic-containing compounds, thereby removing Arsenic from the soil in gaseous form for remediation purposes; however, the reduction of Arsenic by microorganisms may increase the environmental risk of Arsenic in terms of toxicity, but the mobility of reduced trivalent Arsenic is significantly higher than pentavalent Arsenic (see Bissen and Frimel, titled "Arsenic-a review. part I: ocurrence, habit, science, mobility", Acta Hydrochim Hydrobiol, Vol. 31, No. 3, pp. 9-18 (2003)). Thus, Arsenic in soil can be removed by ex-situ elution after reduction of Arsenic by microorganisms (Deng et al, entitled "Bioleaching media of heavy meters in the mixture of synthesized soil and slag by using indigenous microorganisms strain NF 1", "J HazardMater", Vol. 248, No. 7, p. 107. 114 (2013)), while Arsenic in leachates can be removed by chemical or biological methods (Bissen and Frimel, entitled "sensing-a review. part I: occurcurrence, sensitivity, specificity, mobility", "Acta Hydrobiol, Vol. 31, No. 3, p. 9-18 (2003)), which greatly reduces the difficulty of directly removing Arsenic from soil and increases the efficiency of remediation of Arsenic. The bacteria reported to date as being resistant and reducing to arsenic are mainly Shewanella sp, Pseudomonas sp, Serratia sp, Lukasz et al, entitled "differentiation of physiological microorganisms and differentiation of bacterial delivery bacteria", BioMed Res Int, Vol 2014, No. 1, p 841892 (2014); bacillus (Bacillus sp.), Rhodococcus (Rhodococcus sp.), Cellulosimicrobium sp.) (Rehman et al, entitled "sensing and chromium reduction in co-culture of bacterial isolated from induced bacteria in Pakistan", "Microbiology", Vol.82, No. 11, p.428-; pantoea (Pantoea sp.) (Wu et al, titled "Bacillus sp SXB and Pantoea sp IMH," J Appl Microbiol ", Vol.114, No. 4, p.713, 721 (2013)), and the like. But the following problems exist in general: (1) at present, relatively few strains with strong arsenic reduction capability are found, more researches are mainly carried out in the stages of strain screening, cultivation, arsenic reduction capability comparison and the like, and the elution effect of arsenic reducing bacteria under the real soil condition and the restoration research matched with the reduction technology are basically in the blank stage; (2) arsenic entering the soil solution through the reduction of microorganisms also exists in the process of re-adsorption by soil colloid, so that the efficiency of biological leaching repair is greatly reduced; (3) how to remove arsenic in the leaching solution, no end treatment technology designed based on the leaching process exists at present.
[ summary of the invention ]
[ problem to be solved ]
The invention aims to provide a method for repairing arsenic-polluted soil by using a microbial-chemical method.
[ solution ]
The invention is realized by the following technical scheme.
The invention relates to a method for repairing arsenic-polluted soil by using a microorganism-chemical method.
The method comprises the following steps:
A. elution is carried out
The ratio of arsenic-contaminated soil in grams to arsenic-reducing bacteria suspension and stabilizer mixture solution in milliliters is 1: 5-7, culturing the arsenic-polluted soil, the arsenic-reducing bacteria suspension and the stabilizer in a shaking table at the temperature of 26-30 ℃ and the rotating speed of 120-160 rpm for 4.5-5.5 h, and performing centrifugal separation to obtain a supernatant and a precipitate respectively;
B. adsorption
The ratio of supernatant in ml to nanoparticles in g was 50: 0.4-0.8, adding starch modified water-containing iron oxide nanoparticles into the supernatant obtained in the step A, culturing for 2.5-3.5 hours in a shaking table at the temperature of 22-28 ℃ and the rotating speed of 120-160 rpm, and performing centrifugal separation to obtain the supernatant with the arsenic content of less than 0.008 mg/kg; returning the supernatant to be continuously used;
C. treatment of arsenic-removing soil
And D, air-drying the precipitate obtained in the step A, grinding, collecting 100-mesh powder, carrying out nitrolysis by using aqua regia, determining the total arsenic content of the precipitate by adopting an HG-AFS method, and calculating to determine that the biological leaching removal rate of arsenic in soil reaches more than 31.3%, wherein the powder is the restored soil.
According to a preferred embodiment of the present invention, the arsenic-contaminated soil has a particle size of 20 to 200 mesh.
According to a preferred embodiment of the present invention, the arsenic content of the arsenic-contaminated soil is 30 to 80 mg/kg.
According to another preferred embodiment of the invention, the chemical form of arsenic in arsenic-contaminated soils is arsenate, arsenite, monomethylarsenate and dimethylarsenate.
According to another preferred embodiment of the present invention, the soil is red soil, brown soil, black soil, desert soil, paddy soil or saline-alkali soil.
According to another preferred embodiment of the present invention, the arsenic-reducing bacterial suspension has an effective bacterial content of 108A bacterial solution of Pseudomonas taiwanensis (Pseudomonas taiwanensis) with cfu/ml or more.
According to another preferred embodiment of the present invention, the stabilizer is an EDTA solution with a concentration of 0.18-0.22M.
According to another preferred embodiment of the present invention, the starch modified hydrous iron oxide nanoparticle is a nanoparticle having a size of 100 to 150nm, which has superior adsorption property to heavy metals.
According to another preferred embodiment of the present invention, in step C, the air drying is performed by drying the precipitate obtained in step a at room temperature in a natural environment.
According to another preferred embodiment of the present invention, in step C, the water content of the air-dried precipitate is 3 to 7% by weight.
The present invention will be described in more detail below.
The invention relates to a microbial-chemical method for leaching and repairing arsenic-polluted soil, which mainly reduces solid-phase adsorption arsenic of the soil into trivalent arsenic by a microbial strain with strong reduction capability on the arsenic so as to promote the arsenic to enter a soil solution. Arsenic in the soil solution is easily re-complexed with soil colloids, particularly iron oxides. The stabilizer EDTA is added, so that the stabilizer EDTA can be complexed with soil colloid, particularly iron oxide and the like, thereby effectively shielding the soil colloid, particularly the point position on the surface of the iron oxide, which is easy to adsorb arsenic, preventing the secondary adsorption of the arsenic in the soil solution and the soil colloid, finally increasing the content of the arsenic which is easy to elute in the soil solution and improving the efficiency of eluting and repairing; and for the obtained arsenic-containing leacheate, recovering arsenic and the stabilizer EDTA in the soil solution by using the fixing agent which has super strong adsorption effect on the heavy metals of arsenic and the stabilizer EDTA. Finally, the aim of repairing the arsenic-polluted soil is achieved. The functional microorganism adopted in the invention is easy to culture and has strong arsenic reduction capability; the stabilizing agent and the fixing agent are nontoxic, and the fixing agent can be recycled for multiple times.
The invention relates to a method for repairing arsenic-polluted soil by using a microorganism-chemical method.
The method comprises the following steps:
A. elution is carried out
The ratio of arsenic-contaminated soil in grams to arsenic-reducing bacteria suspension to stabilizer mixture solution in milliliters is 1: 5-7, culturing the arsenic-polluted soil, the arsenic-reducing bacteria suspension and the stabilizer in a shaking table at the temperature of 26-30 ℃ and the rotating speed of 120-160 rpm for 4.5-5.5 h, and performing centrifugal separation to obtain a supernatant and a precipitate;
according to the invention, the soil is red soil, brown soil, black soil, desert soil, paddy soil or saline-alkali soil. The granularity of the arsenic-polluted soil is 20-200 meshes. If the granularity of the arsenic-polluted soil exceeds the granularity range, mechanical grinding or water adding solidification and then grinding treatment is needed.
In the invention, the arsenic content of the arsenic-polluted soil is usually 30-80 mg/kg. If the arsenic content exceeds this range, the biological elution effect of the present invention on arsenic in the soil is insignificant.
The chemical form of arsenic in contaminated soil is typically arsenate ions. In the present invention, these arsenic chemical forms are easily handled, resulting in arsenite ions that are reduced and more mobile.
According to the invention, the stabilizing agent is an EDTA solution with the concentration of 0.18-0.22M.
The EDTA in the invention has the basic functions of preventing the arsenic in the soil solution from being adsorbed with the soil colloid for the second time and improving the leaching and repairing efficiency. In the mixed solution, if the concentration of EDTA exceeds the range, the ability of EDTA to shield soil colloid, especially the surface of iron oxide, from arsenic sites is reduced, and the efficiency of arsenic leaching remediation is affected.
In the present invention, the arsenic-reducing bacterial suspension has an effective bacterial content of 108A bacterial solution of Pseudomonas taiwanensis (Pseudomonas taiwanensis) with cfu/ml or more.
The strong tolerance and reducing ability of the strain to arsenic in soil have not been reported. The strain has been identified by 16S rRNA. The morphological characteristics, biological characteristics, bacterial suspension preparation method and other technical contents of pseudomonas taiwanensis can be found in "separation and identification of arsenic-resistant bacteria and research on arsenic oxidation and reduction capability thereof" in "gapeng (university of Hunan agriculture research institute, 2015, 6 months).
Comparative analysis of arsenic resistance of Pseudomonas taiwanensis: 9 arsenic-resistant bacteria (numbered 2-2, 4-1, 4-2, 4-3, 7-1, 7-2, 8-3, 8-4 and 8-5) separated from arsenic-contaminated soil were respectively transferred to beef extract peptone liquid media with arsenic concentrations of 50mg/L, 100mg/L, 200mg/L, 400mg/L and 800mg/L, shake-cultured in a shaker for 48 hours, the OD600 values thereof were measured by an ultraviolet spectrophotometer, and the obtained data were analyzed and processed, and the results are shown in FIG. 1. As is clear from the results shown in FIG. 1, the bacteria numbered 2-2 (identified as Pseudomonas taiwanensis) exhibited the highest arsenic tolerance, particularly, the arsenic-stressed concentration was 0-300 mg.L-1When the biomass (represented by OD 600) was the highest.
Analysis of arsenic-reducing ability of pseudomonas taiwanensis: sucking 1ml of Pseudomonas taiwanensis suspension into a beef extract peptone bacterial culture solution with As (V) concentration of 10mg/L, and placing the beef extract peptone bacterial culture solution into a shaking table for shake culture for 24h, and repeating for four times. During this period, samples were taken every 3 hours to determine the OD value of the culture broth, and the As (III) and As (V) contents were analyzed, the results of which are shown in FIG. 2. These analysis results showed that the OD value of Pseudomonas taiwanensis gradually increased with the increase of the culture time, while As (V) originally added to the culture broth disappeared at the time of 6 hours of culture, and As (III) which is a reduction product of As (V) peaked and stabilized at about 12 hours of culture.
Specifically, for example, 5g of arsenic-contaminated soil (arsenic concentration is 38.53mg/kg) is weighed into a small triangular flask, and the soil is continuously sterilized for three times by adopting a high-temperature and high-pressure sterilization method, so that the interference of the original bacteria on the experimental result is prevented.
Four processes are set: using sterilized ultrapure water as eluent, using sterilized bacteria culture medium (LB bacteria basic culture medium) as eluent, and using pseudomonas taiwanensis bacterial liquid (with effective bacteria content of about 10)8cfu/ml) as eluent, and pseudomonas taiwanensis bacterial liquid (the effective bacterial content is about 10)8cfu/ml) and a stabilizer EDTA (0.2M) are eluent, and the volume of each eluent is 30 ml. Each treatment was repeated three times. The shaking table is cultured for 5 hours at the rotating speed of 140rpm and the temperature of 28 ℃, centrifuged, and the collected supernatant is poured into a 50ml volumetric flask and is subjected to constant volume for standby. Air drying the collected soil sample, grinding and sieving with 100 mesh sieve, weighing 0.5g, digesting with aqua regia, and adopting HG-And (4) determining the total arsenic content by an AFS method. The results of the tests are shown in FIG. 3.
The results in FIG. 3 show that the arsenic content in the leached soil is 38mg/kg and 36mg/kg respectively for the treatment using sterilized ultrapure water and sterilized bacterial culture medium as leacheate, and the arsenic content is reduced to 0.8% and 5.9% respectively relative to the background arsenic content of the soil. Taking pseudomonas taiwanensis bacterial liquid as an eluting agent, wherein the arsenic content of the eluted soil is 22mg/kg, and the arsenic content is reduced to 43.6%; the mixed solution of the pseudomonas taiwanensis bacterial solution and the EDTA as the stabilizer is used as the eluting agent, the arsenic content of the eluted soil is 17mg/kg, and the arsenic content is reduced to 56.4 percent. Among the four treatments, the treatment with the pseudomonas taiwanensis bacterial liquid as the eluting agent has a better effect of eluting the arsenic in the soil, and the treatment with the mixed liquid of the pseudomonas taiwanensis bacterial liquid and the stabilizer EDTA as the eluting agent has the best effect of eluting the arsenic in the soil.
B. Adsorption
The ratio of supernatant in ml to nanoparticles in g was 50: 0.4-0.8, adding starch modified water-containing iron oxide nanoparticles into the supernatant obtained in the step A, culturing for 2.5-3.5 hours in a shaking table at the temperature of 22-28 ℃ and the rotating speed of 120-160 rpm, and performing centrifugal separation to obtain the supernatant with the arsenic content of less than 0.008 mg/kg; returning the supernatant to be continuously used;
taking the mixed solution of pseudomonas taiwanensis bacterial liquid and a stabilizing agent EDTA as supernatant obtained by eluting, and adding a starch modified aqueous iron oxide nanoparticle fixing agent to remove arsenic contained in the supernatant.
According to the invention, the starch modified hydrous iron oxide nanoparticles are nanoparticles with the size of 100-150 nm and super-strong adsorption performance on heavy metals. The basic mechanism of removing arsenic from the starch modified water-containing iron oxide nanoparticles is the strong adsorption effect of the nanoparticles on arsenate, and in addition, the surface area and the arsenic adsorption capacity and capacity of the nanoparticles are increased after the nanoparticles are prepared. In addition, the dispersing ability of the particles is improved after the starch modification, the agglomeration of the particles in a water body or a soil water solution is reduced, and the adsorption surface is relatively greatly increased. The production and preparation processes of starch modified aqueous iron oxide nanoparticles and their arsenic adsorption capacity are described in the article entitled "Enhanced removal of As (V) from aqueous solution using modified hydro us ferri oxide nanoparticles", Scientific Reports, Vol.7, p.40765 (2017).
And (4) analyzing the arsenic content of the supernatant obtained by centrifugal separation by using HG-AFS. The analytical results are shown in FIG. 4. As shown in FIG. 4, after adsorbing arsenic in the leacheate by using the fixing agent, the arsenic content is about 0.1311mg/kg, which is significantly lower than the initial arsenic content of 2.21mg/kg in the leacheate, and the removal rate of arsenic is about 94.1%. However, the arsenic content in the leacheate after the first removal is still higher than the related standard (0.010mg/kg) of arsenic in national water bodies. After the first removal, the second adsorption of the arsenic in the leacheate by using the fixing agent shows that the content of the arsenic in the leacheate is 0.008mg/kg and is obviously lower than the related standard (0.010mg/kg) of the arsenic in the national water body.
C. Treatment of arsenic-removing soil
And D, air-drying the precipitate (arsenic-removed soil) obtained in the step A, sampling and grinding, collecting 100-mesh powder, carrying out nitrolysis by using aqua regia, determining the total arsenic content of the precipitate by adopting an HG-AFS method, and calculating to determine that the biological leaching removal rate of arsenic in the soil reaches more than 31.3%, wherein the air-dried precipitate is the restored soil.
In the invention, the air drying is to dry the precipitate obtained in the step A to 3-7% by weight at room temperature in a natural environment.
[ advantageous effects ]
The invention has the beneficial effects that: the method of the invention is mainly characterized in that the solid-phase adsorption arsenic of the soil is reduced into trivalent arsenic by the microorganism strains with strong reduction capability on arsenic, and then the arsenic is promoted to enter the soil solution. The stabilizer EDTA is added to effectively shield the soil colloid, so that the secondary adsorption of arsenic in the soil solution and the soil colloid is prevented, the content of easily leached arsenic in the soil solution is increased finally, and the leaching and repairing efficiency is improved; and for the obtained arsenic-containing leacheate, recovering arsenic and the stabilizer EDTA in the soil solution by using the fixing agent which has super strong adsorption effect on the heavy metals of arsenic and the stabilizer EDTA. Finally, the aim of repairing the arsenic-polluted soil is achieved. The functional microorganism adopted in the invention is easy to culture and has strong arsenic reduction capability; the stabilizing agent and the fixing agent are nontoxic, and the fixing agent can be recycled for multiple times. The removal rate of arsenic in the arsenic-polluted soil with the total arsenic content of 30-80 mg/kg by adopting the method disclosed by the invention is up to over 31.3%.
[ description of the drawings ]
FIG. 1 is a graph showing the OD values of 9 strains of bacteria cultured in culture solutions with different arsenic concentrations for 48 hours;
FIG. 2 is a graph showing the reducing power of Pseudomonas taiwanensis to As (V);
FIG. 3 is a graph showing the effect of the microbial-chemical method of the present invention on the leaching of arsenic from contaminated soil according to example 1;
FIG. 4 is a graph showing the arsenic content in the soil leacheate obtained after the fixing agent is added twice in example 1.
FIG. 5 is a graph showing the effect of the microbial-chemical method of the present invention on the leaching of arsenic from contaminated soil according to example 2;
FIG. 6 is a graph showing the arsenic content in the soil leacheate obtained after adding the fixing agent twice in example 2.
FIG. 7 is a graph showing the effect of the microbial-chemical method of this example 3 on the leaching of arsenic from contaminated soil;
FIG. 8 is a graph showing the arsenic content in the soil leacheate obtained after adding the fixing agent twice in example 3.
FIG. 9 is a graph showing the effect of the microbial-chemical method of this example 4 on the leaching of arsenic from contaminated soil;
FIG. 10 is a graph showing the arsenic content in the soil leacheate obtained after adding the fixing agent twice in example 4.
[ detailed description ] embodiments
The invention will be better understood from the following examples.
Example 1: the invention utilizes a microorganism-chemical method to repair arsenic-polluted soil
The implementation steps of this example are as follows:
A. elution is carried out
The ratio of arsenic-contaminated soil in grams to arsenic-reducing bacteria suspension to stabilizer mixture solution in milliliters is 1: 5, leading the arsenic with the arsenic content of 39mg/kg, the granularity of 200 meshes and the chemical form of the arsenic to be quinquevalent arsenic to pollute the brown soil and leading the effective bacteria content to be 1.2 multiplied by 108Pseudomonas taiwanensis (Pseudomonas) cfu/mltaiwanensis) bacterial liquid arsenic reducing bacterial suspension and 0.20M EDTA stabilizer, culturing for 4.8h at 26 ℃ and 150rpm in a shaking table, and centrifuging at 6500 rpm by using a centrifuge sold by SIGMA corporation in Germany under the trade name of Sigma 3K15 to obtain supernatant and precipitate;
B. adsorption
The ratio of supernatant in ml to nanoparticles in g was 50: 0.7, adding starch modified aqueous iron oxide nanoparticles having a size of 100nm and having superior adsorption properties to heavy metals to the supernatant obtained in step A, culturing for 2.8h in a shaker at a temperature of 28 ℃ and a rotation speed of 140rpm, and centrifuging at 6500 rpm using a centrifuge sold under the trade name Sigma 3K15, SIGMA, Germany, to obtain a supernatant having an arsenic content of 0.013 mg/kg; and returning the starch modified hydrous iron oxide nanoparticles to be continuously used for adsorbing and removing arsenic in the supernatant, and centrifuging to obtain the supernatant with the arsenic content of 0.008 mg/kg. The second adsorption result shows that the arsenic content in the leacheate is obviously lower than the related standard (0.010mg/kg) of arsenic in national water.
C. Treatment of arsenic-removing soil
And D, air-drying the precipitate obtained in the step A at room temperature in a natural environment until the water content is 3% by weight, grinding, collecting 100-mesh powder, carrying out nitrolysis by using aqua regia, determining the total arsenic content of the precipitate to be 17mg/kg by adopting an HG-AFS method, and determining that the air-dried precipitate is the restored soil. Based on the fact that the content of the arsenic source in the soil in the embodiment is 39mg/kg, the removal rate of the arsenic in the soil by the method is 56.4%.
FIG. 3 is a graph showing the effect of the microbial-chemical method of the present invention on the leaching of arsenic from contaminated soil according to example 1; FIG. 4 is a graph showing the arsenic content in the soil leacheate obtained after the fixing agent was added twice in example 1.
Example 2: the invention utilizes a microorganism-chemical method to repair arsenic-polluted soil
The implementation steps of this example are as follows:
A. elution is carried out
Dissolving the soil polluted by arsenic in grams and the mixture of arsenic reducing bacteria suspension and stabilizer in millilitersThe ratio of liquid to liquid is 1: 6, the content of effective bacteria in the arsenic polluted red soil with the arsenic content of 30mg/kg, the granularity of 100 meshes and the arsenic chemical form of pentavalent arsenic is 1.0 multiplied by 108cfu/ml Pseudomonas taiwanensis (Pseudomonas taiwanensis) bacterial liquid arsenic reducing bacterial suspension and 0.18M EDTA stabilizer, in a shaking table at 28 ℃ and 120rpm under the conditions of culture for 5.5h, by using a German SIGMA company and trade name of Sigma 3K15 Germany, centrifugal separation is carried out at 5000 rotation speed, and supernatant and precipitate are obtained;
B. adsorption
The ratio of supernatant in ml to nanoparticles in g was 50: 0.4, adding 120nm starch modified aqueous iron oxide nanoparticles having strong adsorption properties to heavy metals to the supernatant obtained in step A, culturing for 2.5h at 22 ℃ and 160rpm in a shaker, and centrifuging at 5000 rpm using a centrifuge sold under the trade name Sigma 3K15, Germany, by the company SIGMA, Germany, to obtain a supernatant having an arsenic content of 0.006 mg/kg; and returning the starch modified water-containing iron oxide nanoparticles to be continuously used for adsorbing and removing arsenic in the supernatant, and centrifuging to obtain the supernatant with the arsenic content of 0.003 mg/kg. The second adsorption result shows that the arsenic content in the leacheate is obviously lower than the related standard (0.010mg/kg) of arsenic in national water.
C. Treatment of arsenic-removing soil
And D, air-drying the precipitate obtained in the step A at room temperature in a natural environment until the water content is 5% by weight, grinding, collecting 100-mesh powder, carrying out nitrolysis by using aqua regia, determining the total arsenic content of the precipitate to be 13mg/kg by adopting an HG-AFS method, and determining that the air-dried precipitate is the restored soil. Based on the fact that the content of the arsenic source in the soil is 30mg/kg in the embodiment, the removal rate of arsenic in the soil is 56.7% by the method.
FIG. 5 is a graph showing the effect of the microbial-chemical method of the present invention on the leaching of arsenic from contaminated soil according to example 2; FIG. 6 is a graph showing the arsenic content in the soil leacheate obtained after adding the fixing agent twice in example 2.
Example 3: the invention utilizes a microorganism-chemical method to repair arsenic-polluted soil
The implementation steps of this example are as follows:
A. elution is carried out
The ratio of arsenic-contaminated soil in grams to arsenic-reducing bacteria suspension to stabilizer mixture solution in milliliters is 1: 6, the content of effective bacteria in the arsenic polluted rice soil with the arsenic content of 62mg/kg, the granularity of 150 meshes and the arsenic chemical form of pentavalent arsenic is 1.4 multiplied by 108cfu/ml Pseudomonas taiwanensis (Pseudomonas taiwanensis) bacterial liquid arsenic reducing bacterial suspension and 0.22M EDTA stabilizer, in a shaking table at 30 ℃ and 160rpm under the conditions of culture for 4.5h, by using a German SIGMA company and trade name of Germany Sigma 3K15 in the rotating speed of 7000 centrifugal separation, supernatant and precipitate obtained;
B. adsorption
The ratio of supernatant in ml to nanoparticles in g was 50: 0.8, adding 150nm starch-modified aqueous iron oxide nanoparticles having strong adsorption properties for heavy metals to the supernatant obtained in step A, incubating for 3.5h at a temperature of 24 ℃ and a rotation speed of 120rpm in a shaker, and centrifuging at a rotation speed of 7000 using a centrifuge sold under the trade name Sigma 3K15 from SIGMA, Germany to obtain a supernatant having an arsenic content of 0.28 mg/kg; returning the starch modified water-containing iron oxide nanoparticles to be continuously used for adsorbing and removing arsenic in the supernatant, and then obtaining the supernatant with the arsenic content of 0.28mg/kg through the centrifugation process. And returning the starch modified water-containing iron oxide nanoparticles to be continuously used for adsorbing and removing arsenic in the supernatant, and centrifuging to obtain the supernatant with the arsenic content of 0.007 mg/kg. The second adsorption result shows that the arsenic content in the leacheate is obviously lower than the related standard (0.010mg/kg) of arsenic in national water. C. Treatment of arsenic-removing soil
And D, air-drying the precipitate obtained in the step A at room temperature in a natural environment until the water content is 7% by weight, grinding, collecting 100-mesh powder, carrying out nitrolysis by using aqua regia, determining the total arsenic content of the precipitate to be 40mg/kg by adopting an HG-AFS method, and determining the air-dried precipitate to be the restored soil. Based on the fact that the content of the arsenic source in the soil is 62mg/kg, the removal rate of arsenic in the soil by the method is 35.5%.
FIG. 7 is a graph showing the effect of the microbial-chemical method of this example 3 on the leaching of arsenic from contaminated soil; FIG. 8 is a graph showing the arsenic content in the soil leacheate obtained after the fixing agent was added twice in example 3.
Example 4: the invention utilizes a microorganism-chemical method to repair arsenic-polluted soil
The implementation steps of this example are as follows:
A. elution is carried out
The ratio of arsenic-contaminated soil in grams to arsenic-reducing bacteria suspension to stabilizer mixture solution in milliliters is 1: 7, leading the arsenic with the arsenic content of 80mg/kg, the granularity of 200 meshes and the chemical form of the arsenic to be quinquevalent arsenic to pollute the saline-alkali soil and leading the effective bacteria content to be 1.1 multiplied by 108culturing a bacterium solution arsenic-reducing bacterium suspension of Pseudomonas taiwanensis (Pseudomonas taiwanensis) with more than cfu/ml and 0.19M EDTA stabilizer in a shaking table at the temperature of 27 ℃ and the rotation speed of 140rpm for 5.2h, and performing centrifugal separation at the rotation speed of 8000 by using a centrifugal machine sold by SIGMA company in Germany under the trade name of Sigma 3K15 to obtain a supernatant and a precipitate;
B. adsorption
The ratio of supernatant in ml to nanoparticles in g was 50: 0.5, adding 150nm starch modified aqueous iron oxide nanoparticles having strong adsorption properties to heavy metals to the supernatant obtained in step A, culturing for 3.2h at 26 ℃ and 150rpm in a shaker, and centrifuging at 8000 using a centrifuge sold under the trade name Sigma 3K15, Germany, by the company SIGMA, Germany, to obtain a supernatant having an arsenic content of 0.36 mg/kg; returning the starch modified water-containing iron oxide nanoparticles to be continuously used for adsorbing and removing arsenic in the supernatant, and then obtaining the supernatant with the arsenic content of 0.36mg/kg through the centrifugation process. And returning the starch modified hydrous iron oxide nanoparticles to be continuously used for adsorbing and removing arsenic in the supernatant, and centrifuging to obtain the supernatant with the arsenic content of 0.009 mg/kg. The second adsorption result shows that the arsenic content in the leacheate is obviously lower than the related standard (0.010mg/kg) of arsenic in national water.
C. Treatment of arsenic-removing soil
And D, air-drying the precipitate obtained in the step A at room temperature in a natural environment until the water content is 6% by weight, grinding, collecting 100-mesh powder, carrying out nitrolysis by using aqua regia, determining the total arsenic content of the precipitate to be 55mg/kg by adopting an HG-AFS method, and determining that the air-dried precipitate is the restored soil. Based on the fact that the content of the arsenic source in the soil is 80mg/kg, the removal rate of the arsenic in the soil by the method is 31.3%.
FIG. 9 is a graph showing the effect of the microbial-chemical method of this example 4 on the leaching of arsenic from contaminated soil; FIG. 10 is a graph showing the arsenic content in the soil leacheate obtained after the fixing agent was added twice in example 4.
Claims (7)
1. A method for remedying arsenic-contaminated soil by using a microorganism-chemical method is characterized by comprising the following steps:
A. elution is carried out
The ratio of arsenic-contaminated soil in grams to arsenic-reducing bacteria suspension to stabilizer mixture solution in milliliters is 1: 5-7, culturing the arsenic-polluted soil, the arsenic-reducing bacteria suspension and the stabilizer in a shaking table at the temperature of 26-30 ℃ and the rotating speed of 120-160 rpm for 4.5-5.5 h, and performing centrifugal separation to obtain a supernatant and a precipitate; the arsenic reducing bacteria suspension has effective bacteria content of 108Pseudomonas taiwan of cfu/ml or more (Pseudomonas taiwanensis) Bacterial liquid; the arsenic content of the arsenic-polluted soil is 30-80 mg/kg; the stabilizer is an EDTA solution with the concentration of 0.18-0.22M;
B. adsorption
Adding starch modified aqueous iron oxide nanoparticles to the supernatant obtained in step a in a ratio of supernatant in milliliters to nanoparticles in grams of 50: 0.4-0.8, culturing for 2.5-3.5 h in a shaking table at the temperature of 22-28 ℃ and the rotating speed of 120-160 rpm, and performing centrifugal separation to obtain a supernatant with the arsenic content of less than 0.008 mg/kg; returning the supernatant to be continuously used;
C. treatment of arsenic-removing soil
And D, air-drying the precipitate obtained in the step A, grinding, collecting 100-mesh powder, carrying out nitrolysis by using aqua regia, measuring the total arsenic content of the precipitate by adopting an HG-AFS method, and calculating to determine that the biological leaching removal rate of arsenic in the soil reaches more than 31.3%, so that the precipitate is used as the remediation soil.
2. The method according to claim 1, wherein the particle size of the arsenic-contaminated soil is 20 to 200 mesh.
3. The method of claim 1, wherein the chemical form of arsenic in the arsenic-contaminated soil is arsenate.
4. The method according to claim 1, wherein the soil is red soil, brown soil, black soil, desert soil, paddy soil or saline-alkali soil.
5. The method of claim 1, wherein the starch-modified hydrous iron oxide nanoparticles are nanoparticles having a size of 100-150 nm and superior adsorption properties for heavy metals.
6. The method according to claim 1, wherein in step C, the air drying is performed by drying the precipitate obtained in step a at room temperature in a natural environment.
7. The method according to claim 1, wherein in step C, the water content of the air-dried precipitate is 3-7% by weight.
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| CN107794051B (en) * | 2017-10-27 | 2019-02-12 | 迦百农生态农业发展股份有限公司 | A kind of biological agent of purifying arsenic contamination soil |
| CN108002542B (en) * | 2017-11-30 | 2020-10-27 | 中国科学技术大学 | Application of strain |
| CN108753647B (en) * | 2018-06-12 | 2021-09-10 | 湖北师范大学 | Arsenic-removing immobilized pellet and application thereof |
| CN109158420B (en) * | 2018-08-27 | 2019-10-18 | 湖北师范大学 | A kind of As polluted soil renovation agent and application thereof |
| CN111234835B (en) * | 2020-02-17 | 2021-04-30 | 兰州大学 | Repairing agent for in-situ repairing heavy metal contaminated soil and in-situ repairing method |
| CN111872101B (en) * | 2020-07-23 | 2021-12-14 | 西南科技大学 | Method for treating strontium in soil by using montmorillonite/carbonate mineralized bacteria aggregates |
| CN112358880A (en) * | 2020-10-21 | 2021-02-12 | 华南理工大学 | Microorganism-nano material composite microbial agent and preparation method and application thereof |
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