Method for fixing and magnetically separating arsenic in water by using biomineralization

Abstract

The invention discloses a method for immobilization and magnetic separation of arsenic in water by biomineralization, which comprises the following steps: S1, preparation of a liquid culture medium: dissolving a 60% (volume) sodium lactate solution, sodium nitrate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate and a yeast extract in deionized water in proportion, adjusting the pH value of the culture medium solution to 6.9-7.0, sub-packaging and performing high-pressure sterilization; s2, inoculating a bacteria solution into the sterilized culture medium for amplification culture; s3, preparing a standard arsenic solution; s4, preparing ferric citrate and ferrous chloride solutions; s5, performing MSR-1 biological control mineralization synthesis of magnetosome; 6, MSR-1 induces ferrous iron to precipitate and remove arsenic; and S7, magnetically separating a bacterium-iron-arsenic mixture. The method realizes fixation and separation of As in water, not only retains the advantages of low cost and environmental friendliness of biomineralization polluted water remediation, but also overcomes the defects of low remediation efficiency and potential pollution caused by incapability of recycling.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial remediation of As-contaminated water, and in particular relates to a method for mineralizing, fixing and magnetically separating arsenic in water using microorganisms. Background Art

[0002] As and its inorganic compounds have been classified as Class I carcinogens by the World Health Organization. As exists in nature primarily in the form of two minerals: arsenic oxide and ferric arsenate. Mining, groundwater extraction, and chemical smelting processes expose As originally present in solid phases such as soil or ores to the geological surface environment. Trivalent As is easily oxidized to pentavalent As by oxygen in the air. Under the scouring, erosion, and dissolution of rainwater, surface water, and groundwater, As in the solid phase is mostly converted to AsO4 3- As is highly mobile in water and poses a direct or indirect threat to human health through well water use and river water irrigation. Therefore, effective remediation of As-contaminated water is crucial for safeguarding people's health and social development.

[0003] Currently, common technologies for As remediation in water include adsorption based on single or composite materials, chemical precipitation, ion exchange, flocculation, electrodialysis, and reverse osmosis. Based on the morphological characteristics of As in water and its adsorption properties for compound ions, amorphous iron minerals with abundant As complexing sites, formed by bio-induced mineralization by bacteria such as iron-oxidizing bacteria, have become preferred materials for As removal by adsorption. This bioremediation technology can be used to remediate As-contaminated water in arid, iron-deficient regions. However, As immobilized by bacteria-iron mineral materials remains an unstable contaminant, and bacterial metabolic activity or iron mineral transformation can lead to secondary As release. Therefore, arsenic removal should not be limited to the removal of dissolved arsenic in water; solid arsenic should also be separated from the aquatic environment. In other words, the development of microbial bio-induced mineralization and As immobilization technologies should be coupled with As separation and recovery technologies. Magnetotactic bacteria, through bio-controlled mineralization under microaerobic conditions, form magnetosomes that possess magnetotactic properties. Methods for bio-induced As immobilization and magnetic recovery of bacteria-iron-arsenic complexes while retaining these properties remain to be explored. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a method for fixing arsenic in water by using microbial mineralization and magnetic separation. The method has high fixation efficiency and can achieve arsenic recovery.

[0005] To this end, the present invention adopts the following technical solutions:

[0006] A method for removing and magnetically separating arsenic from water using biomineralization comprises the following steps:

[0007] S1, liquid culture medium preparation:

[0008] Dissolving 60% (volume) sodium lactate solution, sodium nitrate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, and yeast extract in deionized water in proportion to obtain concentrations of 2.2-3 g / L, 0.3-0.4 g / L, 0.1-0.12 g / L, 0.15-0.2 g / L, and 0.1-0.12 g / L, respectively, adjusting the pH of the culture medium solution to 6.9-7.0, and dispensing 50 ml of the culture medium into each 100 ml serum bottle. The serum bottles are then sealed and sterilized under high pressure. After sterilization, the serum bottles are cooled to room temperature to obtain a plurality of sterilized culture media.

[0009] S2, bacterial culture:

[0010] In a sterile operating table, inoculate the Griffiswald Magnetospirillum strain into the sterilized culture medium obtained in S1, seal the serum bottle tightly and place it in a constant temperature shaker to expand the culture. The OD 565 The concentration of the bacterial solution is 0.9 to 1.1, wherein the volume of the Griffiswald Magnetospirillum bacterial solution inoculated in each serum bottle is 5-10% of the volume of the culture medium in the bottle;

[0011] S3, prepare standard arsenic solution:

[0012] Prepare a 1 g / L standard As(V) solution using trisodium arsenate and deionized water;

[0013] S4, prepare ferric citrate and ferrous chloride solution:

[0014] A 200 mg / L ferric citrate solution was prepared using ferric citrate and deionized water; the deionized water was boiled to obtain deoxygenated water, nitrogen was blown through the deoxygenated water until the temperature dropped to room temperature, and then the water was stored in an anaerobic glove box; ferrous chloride was dissolved in the deoxygenated water in the anaerobic glove box to prepare a 1 g / L ferrous chloride solution;

[0015] S5, MSR-1 biologically controlled mineralization and synthesis of magnetosomes:

[0016] Filter the ferric citrate solution and the standard As solution using a sterile filter to remove bacteria; add the filtered ferric citrate solution and the standard As solution to the sterile culture medium obtained in S1, so that the concentration of the ferric citrate solution in the sterile culture medium is 5-50 mg / L and the concentration of As(V) is 0.5-20 mg / L; then inoculate the bacterial solution expanded in step S2, with the inoculum amount being 5-10% of the culture medium volume; place the inoculated sterile culture medium in a constant temperature oscillator and culture for 18-22 hours to obtain a bacterial solution that synthesizes magnetosomes and perform a simple verification;

[0017] S6.MSR-1 induces arsenic removal by ferrous iron precipitation;

[0018] Filter the ferrous chloride solution prepared in S4 through a sterile filter, and inject the filtered ferrous chloride solution into the bacterial solution obtained in S5 in a sterile operating table to make the initial ferrous iron concentration in the bacterial solution 200-600 mg / L, and continue to react in a constant temperature oscillator for 6-12 hours;

[0019] S7. Magnetic separation of bacteria-iron-arsenic mixture:

[0020] A strong magnet was attached to the wall of the serum bottle obtained in S6 for 4-6 hours, and the solid phase mixture accumulated at the magnetic pole of the bottle wall was scraped with a small spoon. The magnetic attraction-scraping operation was repeated until there was no obvious solid phase mixture attached to the bottle wall. The collected mixtures were combined to finally obtain the total arsenic fixed by the bacterial iron precipitate outside the water body.

[0021] In the above S1, the serum bottle is sealed with a gas exchangeable sealing film and placed in a high pressure sterilizer for sterilization at 120-125°C for 20-25 minutes. After sterilization, the serum bottle is placed in a sterile operating table and cooled to room temperature.

[0022] In S1, the pH of the culture medium solution was adjusted using HCl and NaOH.

[0023] In S2 and S5, the temperature of the constant temperature oscillator was 30° C. and the shaking speed was 100 rpm.

[0024] The standard As(V) solution in S3 was prepared as follows: 2.7748 g of trisodium arsenate was accurately weighed, added to 500 ml of deionized water, and ultrasonicated until completely dissolved. The solution was transferred to a 1 L volumetric flask and the volume was made up to 1000 mL with deionized water.

[0025] The simple verification method described in S5 is to determine whether the color of the bacteria changes to gray-black or whether the bacteria rotate with the magnetic field on a magnetic stirrer.

[0026] The present invention uses magnetotactic bacteria biomineralization to remove As pollutants from water as follows: Griffiswald Magnetospirillum (MSR-1) first absorbs iron ions from ferric citrate under microaerobic conditions, then the cell membrane invaginates to form a magnetosome membrane. After the iron ions enter the magnetosome membrane, a protein-regulated redox reaction occurs, ultimately forming biofilm-coated magnetite nanoparticles, also known as magnetosomes. In an environment where ferrous chloride is continuously added, the negatively charged surface of MSR-1 is attracted by charge and adsorbed and complexed with a large amount of positively charged divalent iron ions. Under the accelerated oxidation action of the bacterial extracellular polymer functional groups, a large amount of divalent iron ions is deposited on the bacterial surface as a template to form amorphous iron minerals. During the mineral formation process, As co-precipitation reaction and adsorption and complexation reaction occur simultaneously, thereby achieving the fixation of dissolved arsenic in the water. With the magnetotactic properties imparted to the bacteria by magnetosomes, under the action of an external magnetic field, MSR-1 carries the iron-arsenic co-precipitate and swims in a directional manner in the water, achieving the separation of arsenic pollutants.

[0027] This invention addresses the low efficiency of biomineralization and the inability to effectively separate arsenic in existing microbial mineralization technologies for remediating As-contaminated water. By doing so, the present invention proposes a dual biomineralization remediation method using magnetotactic bacteria, suitable for the efficient fixation and magnetic separation of As in water. This method combines bioinduced mineralization and biocontrolled mineralization by the same microorganism to achieve sequential As fixation and magnetic separation. The specific effects of the two biomineralization methods are as follows: The magnetotactic bacteria MSR-1 forms amorphous iron precipitates through bioinduced mineralization, achieving efficient As fixation in water; and the magnetotactic bacteria MSR-1 synthesizes magnetosomes through biocontrolled mineralization, imparting magnetotactic properties. This allows the separation of the magnetotactic bacteria, loaded with iron-arsenic minerals, from water under the application of a magnetic field.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention uses magnetotactic bacteria to induce divalent iron to complete biological induced mineralization. The ability of magnetotactic bacteria to accommodate or absorb iron is 100-1000 times that of ordinary bacteria. The high affinity of the bacteria for iron ions enables it to quickly induce divalent iron to form a large amount of mineralization using the cell surface as a deposition template, thereby improving the fixation efficiency of As in water.

[0030] 2. The magnetotactic bacteria selected in the present invention have the characteristic of synthesizing magnetosomes within their cells, which gives these bacteria unique and stable magnetotactic properties. This allows for the magnetic separation of biomineralized and fixed As, preventing such As from remaining in the water and becoming an unstable source of secondary pollution. The use of simple magnetic recovery eliminates the cost of subsequent pollutant concentration monitoring.

[0031] 3. The bacterial agents and pharmaceuticals used in the present invention are low-cost, and the repair process is simple and fast, which gives full play to the advantages of bioremediation such as sustainability and environmental friendliness, and improves the shortcomings of bioremediation such as long time consumption, low efficiency, and difficulty in separating pollutants in water.

[0032] 4. The present invention has a wide range of applications. The amorphous iron minerals formed by the biologically induced mineralization of magnetotactic bacteria can be used for the remediation of polluted water environments with anionic pollutants, siderophilic organic pollutants, or the coexistence of the two. Magnetotactic bacteria, as facultative anaerobic bacteria, can be used for the remediation of water pollution under a wide range of dissolved oxygen concentrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the OD of MSR-1 bacterial solution under different As concentrations 565 Value diagram;

[0034] Figure 2 Schematic diagram of the effect of reaction time on the efficiency of As(V) removal by biologically induced ferrous iron precipitation;

[0035] Figure 3 Schematic diagram of the effect of initial As(V) concentration on the efficiency of As(V) removal by biologically induced ferrous iron precipitation;

[0036] Figure 4 Schematic diagram of the effect of initial ferrous iron concentration on the efficiency of As(V) removal by biologically induced ferrous iron precipitation;

[0037] Figure 5 Schematic diagram of the effect of initial ferric citrate concentration on the efficiency of magnetic separation of As(V) in water. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the technical solutions of the present invention are described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] The method of the present invention is to inoculate MSR-1 into a liquid culture medium containing sodium lactate, sodium nitrate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate and yeast extract for activation and expansion culture, then inoculate the expanded cultured bacteria into a liquid culture medium containing trisodium arsenate and ferric citrate, and after the bacteria complete bio-controlled mineralization, i.e., magnetosome synthesis, further add ferrous chloride to enable the bacteria to complete a bio-induced mineralization process, fix As in water by inducing amorphous iron minerals to precipitate on the bacterial surface, and finally separate the MSR-1 and the surface iron-arsenic precipitate from the water body due to its magnetotaxis.

[0040] The Magnetospirillum Griffiswaldii (abbreviated as MSR-1) used in the following examples was purchased from the German Collection of Microorganisms (DSMZ) with the deposit number: DSM 6361.

[0041] Example 1

[0042] Testing the As tolerance of MSR-1 under different As concentrations included the following steps:

[0043] S1. Dissolve 60% sodium lactate solution, sodium nitrate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, and yeast extract in deionized water to concentrations of 2.6 g / L (concentration of sodium lactate solution in deionized water), 0.34 g / L, 0.1 g / L, 0.15 g / L, and 0.1 g / L, respectively. Adjust the pH of the culture medium solution to 7.0, and dispense 50 ml of the culture medium into each 100 ml serum bottle. After sealing the serum bottles with gas-exchange sealing film, place the serum bottles in an autoclave and sterilize them at 120°C for 20 min. After sterilization, place the culture medium in a sterile operating table and cool it to room temperature to obtain multiple sterilized culture media.

[0044] S2. In a sterile operating table, take a portion of the sterilized culture medium and inoculate 5-10% of the volume of the MSR-1 bacterial solution. Seal the serum bottle with a rubber stopper and an aluminum cap. Place the bottle in a constant temperature shaker (30°C, 100 rpm) to expand the culture and obtain the OD 565 For the bacterial liquid.

[0045] S3. Accurately weigh 2.7748 g of trisodium arsenate, add it to 500 ml of deionized water, and sonicate until completely dissolved. Transfer the solution to a 1 L volumetric flask and add deionized water to make the volume 1000 mL to obtain a 1 g / L standard As(V) solution.

[0046] S4. Filter the standard As solution using a sterile filter, dilute the standard As(V) solution stepwise with sterile water in a sterile operating table, add As(V) solutions of different concentrations to the sterile culture medium obtained in S1, so that the concentration of As(V) in the culture medium is 0, 0.5, 5, 20, 50, and 200 mg / L, respectively, and inoculate the bacterial solution obtained in S2 with an inoculum volume of 5-10% of the culture medium volume, and place the culture in a constant temperature oscillator (30°C, 100 rpm) for culture.

[0047] S5. Take samples of the bacterial solution cultured in step S4 at intervals of 0-24 hours and measure the OD of the bacterial solution using a spectrophotometer. 565 value.

[0048] Figure 1 is the OD of bacterial solution at different As(V) concentrations 565 It can be seen that the dissolved As concentration in the range of 0-50 mg / L has no significant effect on bacterial growth, and MSR-1 has good arsenic tolerance.

[0049] Example 2

[0050] The test of the As removal ability of biologically induced ferrous iron precipitation at different reaction times includes the following steps:

[0051] S1 to S3 are the same as those in Example 1.

[0052] S4. Weigh 200 mg of ferric citrate and dissolve it in 1 L of deionized water to obtain a 200 mg / L ferric citrate solution. Boil the deionized water and purge it with nitrogen for 1 hour. After the deionized water cools to room temperature, store it in an anaerobic glove box. Weigh 2.2695 g of ferrous chloride and dissolve it in 1 L of deionized water in the anaerobic glove box to obtain a 1 g / L ferrous chloride solution.

[0053] S5. Filter the ferric citrate and standard As(V) solutions using a sterile filter, add the ferric citrate solution and As(V) solution to the sterilized culture medium obtained in S1, so that the concentration of the ferric citrate solution in the culture medium is 15 mg / L and the concentration of As(V) is 50 mg / L, and inoculate the OD obtained by the expanded culture in step S2. 565 The bacterial solution with a concentration of 1.0 was placed in a constant temperature oscillator (30°C, 100 rpm) for cultivation. After 18 hours, the dissolved oxygen concentration in the solution reached the microaerobic condition suitable for magnetosome synthesis.

[0054] S6. In a sterile operating table, use a syringe to extract 1-2 ml of the bacterial solution that has reached microaerobic conditions in S5. Determine whether MSR-1 has successfully synthesized magnetosomes by observing the color change of the bacteria or whether the bacteria respond to the magnetic field changes of the magnetic stirrer.

[0055] Specifically, when the bacterial color changes from its original white or light pink to gray-black and the overall color of the water becomes darker, it indicates that the Griffiswald Magnetospirillum is synthesizing magnetosomes within its cells. Alternatively, place the serum bottle on a turned-on magnetic stirrer. If the bacterial colony is observed swirling within the bottle, it indicates that magnetosomes have been successfully synthesized.

[0056] S7. Filter the ferrous chloride solution through a sterile filter. In a sterile operating table, inject the ferrous chloride solution into the bacterial solution after the magnetosome synthesis confirmed in step S5. The initial divalent iron concentration is 200 mg / L. Samples are taken at intervals within 15 hours. After filtering through a 0.22 μM filter membrane, the As(V) concentration is measured by ICP-MS.

[0057] Figure 2 The figure shows the effect of different reaction times on the efficiency of biologically induced ferrous iron precipitation in removing As(V). As can be seen, the As(V) removal rate reaches its highest level 12 hours after the addition of ferrous chloride, indicating that the MSR-1 biologically induced ferrous iron precipitation reaction can achieve efficient As(V) fixation in water within 12 hours.

[0058] Example 3

[0059] The ability of biologically induced ferrous iron precipitation to remove As(V) at different initial As(V) concentrations was tested, including the following steps:

[0060] S1 to S4 are the same as those in Example 2.

[0061] S5. Filter the ferric citrate and standard As(V) solutions using a sterile filter, add the ferric citrate solution and As(V) solutions of varying concentrations to the sterilized culture medium obtained in S1, so that the ferric citrate solution concentration in the culture medium is 15 mg / L and the As(V) concentration is 0, 0.5, 5, 20, 50, and 200 mg / L, and inoculate the culture medium with the OD values ​​obtained by the expanded culture in step S2. 565 The bacterial solution was 1.0 and cultured in a constant temperature oscillator (30°C, 100 rpm). After 18 hours, the dissolved oxygen concentration in the solution reached microaerobic conditions and magnetosomes were synthesized.

[0062] S6. Use a syringe to extract 1-2 ml of the bacterial solution cultured for 18-22 hours in step S5 in a sterile operating table. Determine whether MSR-1 has successfully synthesized magnetosomes by observing the color change of the bacteria and whether the bacteria respond to the magnetic field changes of the magnetic stirrer.

[0063] S7. Filter the ferrous chloride solution through a sterile filter. In a sterile operating table, inject the ferrous chloride solution into the bacterial solution after the magnetosome synthesis confirmed in step S5. The initial divalent iron concentration is 200 mg / L. Sample at 12 hours, filter through a 0.22 μM filter membrane, and test the As(V) concentration by ICP-MS.

[0064] Figure 3 The figure below shows the effect of initial As(V) concentration on As(V) removal efficiency through biologically induced ferrous iron precipitation. As can be seen, when the initial ferrous iron concentration is 200 mg / L, the As(V) removal efficiency is above 90% for initial As concentrations ranging from 0.5 to 20 mg / L, demonstrating excellent removal efficiency.

[0065] Example 4

[0066] The ability of biologically induced ferrous iron precipitation to remove As(V) was tested at different initial ferrous chloride concentrations, including the following steps:

[0067] S1 to S4 are the same as those in Example 2.

[0068] S5. Filter the ferric citrate and standard As(V) solutions using a sterile filter, add the ferric citrate solution and As(V) solution to the sterilized culture medium obtained in S1, so that the concentration of the ferric citrate solution in the culture medium is 15 mg / L and the concentration of As(V) is 20 mg / L, and inoculate the OD obtained by the expanded culture in step S2. 565 The bacterial solution with a concentration of 1.0 was placed in a constant temperature oscillator (30°C, 100 rpm) for culture. After 18 hours, the dissolved oxygen concentration in the solution reached the microaerobic condition suitable for magnetosome synthesis.

[0069] S6. Use a syringe to extract 1-2 ml of the bacterial solution that reached microaerobic conditions in step S5 in a sterile operating table. Determine whether MSR-1 has successfully synthesized magnetosomes by observing the color change of the bacteria and whether the bacteria respond to the magnetic field changes of the magnetic stirrer.

[0070] S7. Filter the ferrous chloride solution through a sterile filter. On a sterile operating table, inject different concentrations of ferrous chloride solution into the bacterial solution after the magnetosome synthesis confirmed in step S5, so that the initial divalent iron concentration is 0, 20, 80, 200, 400, and 600 mg / L. Samples are taken 12 hours after the reaction, filtered through a 0.22 μM filter membrane, and then the As(V) concentration is tested by ICP-MS.

[0071] Figure 4 The figure shows the effect of initial ferrous iron concentration on the As(V) removal efficiency by biologically induced ferrous iron precipitation. It can be seen that when the initial ferrous iron concentration is in the range of 200-600 mg / L, the As removal efficiency can be higher than 90%.

[0072] Example 5

[0073] The test of magnetic separation efficiency of As in water with different initial ferric citrate concentrations includes the following steps:

[0074] S1 to S4 are the same as those in Example 2.

[0075] S5. Filter the ferric citrate and standard As(V) solutions using a sterile filter, add the ferric citrate solution and As(V) solution to the sterilized culture medium obtained in S1, adjust the concentration of the ferric citrate solution in the culture medium to 0, 1, 5, 15, 50, and 200 mg / L, and the concentration of As(V) to 20 mg / L, and inoculate the OD obtained by the expanded culture in step S2. 565 The bacterial solution with a concentration of 0.9 to 1.1 was placed in a constant temperature oscillator (30°C, 100 rpm) for culture. After 18 hours, the dissolved oxygen concentration in the solution reached the microaerobic condition suitable for magnetosome synthesis.

[0076] S6. Use a syringe to extract 1-2 ml of the bacterial solution that reached microaerobic conditions in step S5 in a sterile operating table. Determine whether MSR-1 has successfully synthesized magnetosomes by observing the color change of the bacteria and whether the bacteria respond to the magnetic field changes of the magnetic stirrer.

[0077] S7. Filter the ferrous chloride solution through a sterile filter. In a sterile operating table, inject the ferrous chloride solution into the bacterial solution grown for 24 hours in step S5. The initial iron concentration is 200 mg / L. After continuing the reaction for 12 hours, at the 36th hour, attach a strong magnet to the wall of the serum bottle for 4 hours. Use a small spoon to scrape the solid phase mixture accumulated at the magnetic pole of the bottle wall. Repeat this process 2-3 times. Combine the collected mixtures and digest the mixture by adding 3 ml of concentrated nitric acid for 12 hours. After diluting and filtering the obtained digestion solution, use ICP-MS to test the As(V) content and further calculate the As(V) recovery rate.

[0078] Figure 5 The figure below shows the effect of initial ferric citrate concentration on the efficiency of magnetic separation of As(V) from water. As can be seen, magnetic recovery rates of As(V) can reach 82%-92% at initial ferric citrate concentrations of 5-50 mg / L, reaching a maximum of 92% at an initial ferric citrate concentration of 15 mg / L.

Claims

1. A method for fixing and magnetically separating arsenic in water using biomineralization, characterized in that: The following steps are involved: S1, liquid culture medium preparation: Dissolve 60% (volume) sodium lactate solution, sodium nitrate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate and yeast extract in deionized water in proportion to make their concentrations 2.2-3 g / L, 0.3-0.4 g / L, 0.1-0.12 g / L, 0.15-0.2 g / L and 0.1-0.12 g / L, respectively, adjust the pH of the culture medium solution to 6.9-7.0, dispense 50 ml of the culture medium into each 100 ml serum bottle, then seal the serum bottle and sterilize it under high pressure, and after the sterilization is completed, cool the serum bottle to room temperature to obtain a plurality of sterilized culture media; S2, bacterial culture: In a sterile operating table, inoculate the Griffiswald Magnetospirillum liquid into the partially sterilized culture medium obtained in S1, seal the serum bottle tightly and place it in a constant temperature oscillator for expansion culture, and obtain the OD 565 The volume of the bacterial solution is 0.9 to 1.1, wherein the volume of the Griffiswald Magnetospirillum bacterial solution inoculated in each serum bottle is 5-10% of the volume of the culture medium in the bottle; S3, prepare standard arsenic solution: Prepare a 1 g / L standard As(V) solution using trisodium arsenate and deionized water; S4, prepare ferric citrate and ferrous chloride solution: A 200 mg / L ferric citrate solution is prepared with ferric citrate and deionized water; the deionized water is boiled to obtain deoxygenated water, nitrogen is blown until the temperature of the deoxygenated water drops to room temperature, and then the deoxygenated water is stored in an anaerobic glove box; ferrous chloride is dissolved in deoxygenated water in the anaerobic glove box to prepare a 1 g / L ferrous chloride solution; S5, MSR-1 biologically controls the mineralization and synthesis of magnetosomes: The ferric citrate solution and the standard As solution are filtered using a sterile filter to remove bacteria; the filtered ferric citrate solution and the standard As solution are added to the sterile culture medium obtained in S1, so that the concentration of the ferric citrate solution in the sterile culture medium is 5-50 mg / L, and the concentration of As(V) is 0.5-20 mg / L, and then the bacterial solution expanded and cultured in step S2 is inoculated, and the inoculation amount is 5-10% of the volume of the culture medium, and the inoculated sterile culture medium is placed in a constant temperature oscillator for 18-22 hours to obtain a bacterial solution that synthesizes magnetosomes and conduct a simple verification; S6.MSR-1 induces arsenic removal by ferrous iron precipitation; Filter the ferrous chloride solution prepared in S4 using a sterile filter, inject the filtered ferrous chloride solution into the bacterial solution obtained in S5 in a sterile operating table, so that the initial ferrous iron concentration in the bacterial solution is 200-600 mg / L, and continue to react in a constant temperature oscillator for 6-12 hours; S7. Magnetic separation of bacteria-iron-arsenic mixture: Attach a strong magnet to the wall of the serum bottle obtained by S6 for 4-6 hours, use a small spoon to scrape the solid phase mixture gathered at the magnetic pole of the bottle wall, repeat the magnetic attraction-scraping operation until there is no obvious solid phase mixture attached to the bottle wall, combine the collected mixtures, and finally obtain the total arsenic fixed by the bacterial iron precipitate outside the water body.

2. The method according to claim 1, characterized in that: In S1, the serum bottle is sealed with a gas exchangeable sealing film and placed in a high pressure sterilizer for sterilization at 120-125° C. for 20-25 min. After sterilization, the serum bottle is placed in a sterile operating table and cooled to room temperature.

3. The method according to claim 1, characterized in that: HCl and NaOH were used to adjust the pH of the culture medium solution in S1.

4. The method according to claim 1, characterized in that: In S2 and S5, the temperature of the constant temperature oscillator was 30°C and the shaking speed was 100 rpm.

5. The method according to claim 1, characterized in that The preparation method of the standard As(V) solution in S3 is as follows: accurately weigh 2.7748 g of trisodium arsenate, add it to 500 ml of deionized water and sonicate until it is completely dissolved, transfer the solution to a 1 L volumetric flask, and add deionized water to make up to 1000 mL.

6. The method according to claim 1, characterized in that The simple verification method described in S5 is to judge by whether the color of the bacteria changes to gray-black or whether the bacteria rotate with the magnetic field on the magnetic stirrer.

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