SRB biological reaction network and preparation method and application thereof

Abstract

The present application relates to the technical field of heavy metal pollution remediation, and particularly relates to a SRB biological reaction net and a preparation method and application thereof.The present application provides a preparation method of the SRB biological reaction net, comprising the following steps: (1) mixing and stirring iron manganese phosphate, sulfate-reducing bacteria and a sodium alginate solution to obtain a mixed solution; (2) immersing a metal net in the mixed solution, and then taking out the metal net and placing it in a calcium chloride solution for solidification.The SRB biological reaction net prepared by the present application can improve the activity of sulfate-reducing bacteria, weaken the influence of heavy metals on the sulfate-reducing bacteria, reduce the loss of bacterial bodies and materials caused by groundwater flow, and improve the material utilization rate.The preparation method of the present application is simple, the product has good stability, and can be widely used.

Description

Technical Field

[0001] This invention relates to the field of heavy metal pollution remediation technology, and in particular to an SRB bioreactor network, its preparation method, and its application. Background Technology

[0002] In recent years, countries around the world have been committed to building new nuclear power reactors. However, it is undeniable that uranium resources are scarce, and uranium ore is mostly low-grade. This leads to relatively low mining efficiency, requiring the extraction of more ore to produce a certain amount of fuel. Consequently, uranium, iron, manganese, and other metallic elements produced during mining enter the groundwater, polluting the groundwater in mining areas. Therefore, we urgently need a new method for treating groundwater in uranium mining areas.

[0003] This type of wastewater causes multiple forms of pollution when it enters the environment: acidic water causes soil compaction and harms crop growth; H2S dissolved in the water has a serious toxic effect on organisms and will also pollute the atmosphere when it escapes into the air; heavy metal ions cannot be biodegraded in the environment, accumulate continuously and are difficult to remove, causing long-term harm to the environment and human health.

[0004] Traditional treatment methods mainly fall into two categories: First, the limestone or lime neutralization method, which involves adding lime or limestone to the wastewater to neutralize the acidic wastewater. However, this method produces large amounts of calcium sulfate and heavy metal precipitates that accumulate in the environment, causing secondary pollution that is difficult to remove. Second, the wetland method. The advantages of the wetland method are low investment and low operating costs, but it requires a large area, is severely affected by environmental factors, and the treatment is not thorough. When acidity is high, wetland treatment has limitations, and many people question its long-term effectiveness.

[0005] Sodium alginate, widely found in alginic acid, is a binary linear polymer composed of β-1,4-D-mannuronic acid and α-1,4-L-guluronic acid. It possesses advantages such as non-toxicity, good biocompatibility, and biodegradability. It can form hydrogels with polyvalent cations such as calcium ions, a process that occurs in a very mild environment. Therefore, the excellent gelling and film-forming properties of alginate and its sodium salts are widely used for the release or encapsulation of drugs, proteins, and cells.

[0006] Sulfate-reducing bacteria (SRB) are a unique group of prokaryotic physiology. They are a group of strict anaerobic bacteria with various morphological characteristics that can reduce sulfate by using sulfate as an electron acceptor for organic matter through dissimilation.

[0007] Iron-manganese phosphate, as an emerging material for environmental wastewater treatment, generates PO4. 3- OH -It can effectively chelate with heavy metal ions in water, and finally the iron ions form colloidal complexes with heavy metals to flocculate and precipitate.

[0008] Therefore, how to utilize the characteristics of sulfate-reducing bacteria and apply them to the treatment of heavy metal pollution in groundwater in uranium mining areas is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing and applying an SRB bioreactor network. The SRB bioreactor network prepared by this invention can enhance the activity of sulfate-reducing bacteria, weaken the impact of heavy metals on sulfate-reducing bacteria, reduce the loss of bacteria and materials due to groundwater flow, and improve material utilization. The preparation method of this invention is simple, the product has good stability, and it can be widely promoted and used.

[0010] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0011] This invention provides a method for preparing an SRB bioreactor network, comprising the following steps:

[0012] (1) Mix and stir the iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution to obtain a mixed solution;

[0013] (2) Immerse the metal mesh in the mixture, and then place it in a calcium chloride solution to solidify.

[0014] Preferably, the mass-to-volume ratio of iron-manganese phosphate, sulfate-reducing bacteria, and sodium alginate solution in step (1) is 0.01~0.05g: 8~12ml: 0.5~1.5ml; the bacterial concentration of sulfate-reducing bacteria in step (1) is OD. 600 =0.4~0.8.

[0015] Preferably, the mass concentration of the sodium alginate solution in step (1) is 1.5~2.0%.

[0016] Preferably, the stirring speed in step (1) is 300~500 r / min.

[0017] Preferably, the stirring time in step (1) is 10 to 30 minutes.

[0018] Preferably, the mass concentration of the calcium chloride solution in step (2) is 1-5%;

[0019] Preferably, the curing time in step (2) is 30~50 min.

[0020] Preferably, the metal mesh in step (2) is made of iron.

[0021] Preferably, the metal mesh in step (2) has a size of 20~80×20~80mm.

[0022] Preferably, the soaking time in step (2) is 5 to 15 minutes.

[0023] The present invention also provides the method for preparing the SRB bioreactor network and the resulting SRB bioreactor network.

[0024] The present invention also provides a method for preparing the aforementioned SRB bioreactor network, and the application of the aforementioned SRB bioreactor network in the remediation of heavy metal pollution in groundwater in uranium mining areas.

[0025] Preferably, the heavy metal is arsenic and / or cadmium.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Iron-manganese phosphate, as an emerging material for environmental wastewater treatment, generates PO4. 3- OH - It can effectively chelate with heavy metal ions in water, and finally the iron ions form colloidal complexes with heavy metals to flocculate and precipitate. The combination of multiple methods can achieve the purpose of removing heavy metal ions from water.

[0028] 2. During in-situ remediation, microbial capsules are lost due to water flow, further increasing the amount of bacteria required and causing unnecessary bacterial loss, while also reducing usage costs. The use of galvanized wire mesh avoids these drawbacks and also prevents the wire mesh from being eroded by water flow and S... 2- Corrosion of wire mesh by ions.

[0029] 3. The SRB bioreactor network prepared by this invention can reduce the loss of bacteria and materials caused by groundwater flow and improve material utilization. Sodium alginate, widely found in alginic acid, is a binary linear polymer composed of β-1,4-D-mannuronic acid and α-1,4-L-guluronic acid. It has advantages such as non-toxicity, good biocompatibility, and biodegradability. It can form hydrogels with polyvalent cations such as calcium ions, a process that takes place in a very mild environment. The excellent gel-forming and film-forming properties of alginate and its sodium salt are widely used for releasing or encapsulating drugs, proteins, and cells. The properties of sodium alginate can enhance the activity of sulfate-reducing bacteria and weaken the effects of heavy metals on sulfate-reducing bacteria.

[0030] 4. The reaction net prepared by the method of this invention, when supplemented with FMP material, achieves a better removal effect compared to traditional microbial capsules. The preparation method of this invention is simple, the product has good stability, and it can be widely applied in the field of groundwater treatment in uranium mining areas. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0032] Figure 1 This is a graph showing the changes in cadmium and arsenic content in the water body of Experiment Example 1;

[0033] Figure 2 This is a simplified flowchart of the present invention;

[0034] Figure 3 This is a diagram illustrating the mechanism of action between iron and manganese phosphate and sulfate-reducing bacteria. Detailed Implementation

[0035] This invention provides a method for preparing an SRB bioreactor network, comprising the following steps:

[0036] (1) Mix and stir the iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution to obtain a mixed solution;

[0037] (2) Immerse the metal mesh in the mixture, and then place it in a calcium chloride solution to solidify.

[0038] In this invention, the mass-to-volume ratio of iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution in step (1) is 0.01~0.05g:8~12ml:0.5~1.5ml; preferably 0.02~0.04g:9~11ml:0.7~1.3ml; further preferably 0.03g:10ml:0.9~1.1ml; and even more preferably 0.03g:10ml:1ml.

[0039] In this invention, the concentration of sulfate-reducing bacteria in step (1) is OD. 600 =0.4~0.8; preferably OD 600 =0.5~0.7; further preferred OD 600 =0.6.

[0040] In this invention, the mass concentration of the sodium alginate solution in step (1) is 1.5~2.0%; preferably 1.6~1.9%; more preferably 1.7~1.8%; and even more preferably 1.8%.

[0041] In this invention, the stirring speed in step (1) is 300~500 r / min; preferably 340~460 r / min; more preferably 380~420 r / min; and more preferably 400 r / min.

[0042] In this invention, the stirring time in step (1) is 10-30 min; preferably 14-26 min; more preferably 18-22 min; and more preferably 20 min.

[0043] In this invention, the mass concentration of the calcium chloride solution in step (2) is 1-5%; preferably 2-4%; and more preferably 3%.

[0044] In this invention, the curing time in step (2) is 30-50 min; preferably 34-46 min; more preferably 38-42 min; and more preferably 40 min.

[0045] In this invention, the metal mesh in step (2) is made of iron; preferably galvanized iron.

[0046] In this invention, the specifications of the metal mesh in step (2) are 20~80×20~80mm; preferably 30~70×30~70mm; further preferably 40~60×40~60mm; and more preferably 50×50mm.

[0047] In this invention, the soaking time in step (2) is 5 to 15 minutes; preferably 7 to 13 minutes; more preferably 9 to 11 minutes; and more preferably 10 minutes.

[0048] The present invention also provides the method for preparing the SRB bioreactor network and the resulting SRB bioreactor network.

[0049] The present invention also provides a method for preparing the aforementioned SRB bioreactor network, and the application of the aforementioned SRB bioreactor network in the remediation of heavy metal pollution in groundwater in uranium mining areas.

[0050] In this invention, the heavy metal is arsenic and / or cadmium; preferably arsenic and cadmium.

[0051] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] A method for preparing an SRB bioreactor network, comprising the following steps:

[0054] (1) Mix ferric phosphate, manganese phosphate and water in a mass ratio of 1:1:5, with a molar ratio of 1:1 for iron and manganese. Stir until dissolved, and place the dissolved solution in a forced-air drying oven. React at 180°C for 6 hours to obtain material 1. Place material 1 in a freeze dryer and freeze dry at -50°C for 14 hours. Then grind it into powder using a mortar and pestle to obtain iron-manganese phosphate.

[0055] (2) Prepare post-gate medium, place it in a 500 mL anaerobic bottle, sterilize it, inoculate with 10% logarithmic phase SRB bacterial solution, and culture under anaerobic conditions at 30 ℃ for 4 days to obtain sulfate-reducing bacteria (OD). 600 =0.4);

[0056] (3) Mix iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution with a mass concentration of 1.5% and stir at 300 r / min for 10 min to obtain a mixture;

[0057] The mass-to-volume ratio of the iron-manganese phosphate, sulfate-reducing bacteria, and sodium alginate solution was 0.01 g: 8 ml: 0.5 ml.

[0058] (4) Immerse the galvanized iron mesh (20×20mm) in the mixture for 5 minutes, then remove it and place it in a 1% calcium chloride solution for 30 minutes to cure.

[0059] Example 2

[0060] A method for preparing an SRB bioreactor network, comprising the following steps:

[0061] (1) Mix ferric phosphate, manganese phosphate and water in a mass ratio of 1:1:5, with a molar ratio of 1:1 for iron and manganese. Stir until dissolved, and place the dissolved solution in a forced-air drying oven. React at 185°C for 7 hours to obtain material 1. Place material 1 in a freeze dryer and freeze dry at -60°C for 14 hours. Then grind it into powder using a mortar and pestle to obtain iron-manganese phosphate.

[0062] (2) Prepare post-gate medium, place it in a 500 mL anaerobic bottle, sterilize it, inoculate with 10% logarithmic phase SRB bacterial solution, and culture under anaerobic conditions at 30 ℃ for 4 days to obtain sulfate-reducing bacteria (OD). 600 =0.8);

[0063] (3) Mix iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution with a mass concentration of 2.0%, stir at 500 r / min for 30 min to obtain a mixture;

[0064] The mass-to-volume ratio of the iron-manganese phosphate, sulfate-reducing bacteria, and sodium alginate solution was 0.05 g: 12 ml: 1.5 ml.

[0065] (4) Immerse the galvanized iron mesh (80×80mm) in the mixture for 15 minutes, then remove it and place it in a 5% calcium chloride solution to cure for 50 minutes.

[0066] Example 3

[0067] A method for preparing an SRB bioreactor network, comprising the following steps:

[0068] (1) Mix ferric phosphate, manganese phosphate and water in a mass ratio of 1:1:5, with a molar ratio of 1:1 for iron and manganese. Stir until dissolved, and place the dissolved solution in a forced-air drying oven. React at 185°C for 7 hours to obtain material 1. Place material 1 in a freeze dryer and freeze dry at -60°C for 14 hours. Then grind it into powder using a mortar and pestle to obtain iron-manganese phosphate.

[0069] (2) Prepare post-gate medium, place it in a 500 mL anaerobic bottle, sterilize it, inoculate with 10% logarithmic phase SRB bacterial solution, and culture under anaerobic conditions at 30 ℃ for 4 days to obtain sulfate-reducing bacteria (OD). 600 =0.6);

[0070] (3) Mix iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution with a mass concentration of 1.8% and stir at 400 r / min for 20 min to obtain a mixture;

[0071] The mass-to-volume ratio of the iron-manganese phosphate, sulfate-reducing bacteria, and sodium alginate solution is 0.03 g: 10 ml: 1 ml;

[0072] (4) Immerse the galvanized iron mesh (50×50mm) in the mixture for 10 minutes, then remove it and place it in a 3% calcium chloride solution for 40 minutes to cure.

[0073] Experimental Example 1

[0074] The RZ wellhead was selected at the uranium mine of CNNC Xinjiang Tianshan Uranium Plant 737 in Yining City, Xinjiang Uygur Autonomous Region. Groundwater was collected at a depth of 100 m using an empty-type sampler. The collected water sample was filtered using a 0.22 μm filter membrane to obtain the filtrate.

[0075] Prepare six 500 mL anaerobic bottles and sterilize them at 121 °C for 20 min. Inoculate each bottle with 300 mL of the above filtrate and irradiate with a UV lamp for 30 min. Add 5 g / L LSRB microbial capsules (the product prepared in Example 1 of CN202210257680.X) and 5 cm³ of [unclear text - possibly a typo, should be "5 cm"]. Five SRB bioreactors from Example 3 were connected in parallel using a 5cm bioreactor mesh, with three anaerobic bottles treated in each mesh. The oxygen content inside the bottles was ≤0.7% after blowing with N2. The bottles were then statically incubated at 30℃ for 7 days. 5 mL samples were taken daily using a sterile syringe. ICP-OES was used to quantitatively analyze the changes in cadmium and arsenic content in the water. The resulting curves are shown below. Figure 1 As shown:

[0076] like Figure 1 As shown, after seven days of treatment, the SRB bioreactor network exhibited better removal efficiency for arsenic and cadmium than the SRB capsules under static conditions. It is worth noting that in actual in-situ groundwater treatment processes, there is a risk of raw material loss due to water flow. The SRB bioreactor network avoids water loss associated with the microbial capsule technology, while also preventing the wire mesh from being eroded by water flow and S... 2- Corrosion of wire mesh by ions.

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a SRB bioreactor network, characterized by, The method comprises the following steps: (1) mixing and stirring iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution to obtain a mixed solution; (2) immersing a metal mesh in the mixed solution, and then taking out the metal mesh and placing it in a calcium chloride solution for solidification; In step (1), the mass-volume ratio of the iron-manganese phosphate, sulfate-reducing bacteria and sodium alginate solution is 0.01-0.05 g:8-12 ml:0.5-1.5 ml; in step (1), the bacterial concentration of the sulfate-reducing bacteria is OD600=0.4-0.8; and the mass concentration of the sodium alginate solution is 1.5-2.0%.

2. The method for preparing an SRB bioreactor network according to claim 1, characterized in that, In step (1), the stirring speed is 300-500 r / min, and the stirring time is 10-30 min.

3. The method for preparing an SRB bioreactor network according to claim 1, characterized in that, In step (2), the mass concentration of the calcium chloride solution is 1-5%, and the solidification time is 30-50 min.

4. The method for preparing an SRB bioreactor network according to claim 1, characterized in that, In step (2), the metal mesh is made of iron, and the size of the metal mesh is 20-80×20-80 mm.

5. The method for preparing an SRB bioreactor network according to claim 1, characterized in that, In step (2), the immersion time is 5-15 min.

6. The SRB biological reaction net prepared by the method of any one of claims 1-5.

7. The application of the SRB biological reaction net of claim 6 in the remediation of heavy metal pollution in groundwater in a uranium mining area.

8. Use according to claim 7, characterized in that, The heavy metal is arsenic and / or cadmium.

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