Thiobacillus thiooxidans suitable for leaching of La and Ce

Abstract

This invention relates to the field of environmental protection and discloses *Acidithiobacillus caldus*, a thermophilic thiobacterium suitable for La and Ce leaching. The preservation number of this *Acidithiobacillus caldus* is CCTCC No: M2021709. The *Acidithiobacillus caldus* described in this invention can tolerate high doses of FCC waste catalyst and has a significant removal effect on metals in FCC waste catalyst, especially La and Ce, making it suitable for the bioleaching treatment of FCC waste catalyst.

Description

Technical Field

[0001] This invention relates to the field of environmental protection, specifically to a strain of Acidithiobacillus caldus and a bacterial agent, as well as their application in biometallurgy and bioleaching for the removal of metals from waste, and a method for the bioleaching removal of metals from waste. Background Technology

[0002] Fluidized catalytic cracking (FCC) catalysts are currently the most consumed refining catalysts, accounting for up to 70% of total refining catalyst usage. During use, FCC catalysts lose activity due to the deposition of metal components such as nickel and vanadium from coke and feedstock oil, rendering them unusable and turning them into spent catalysts. Because FCC spent catalysts contain highly hazardous metals such as Ni, V, and Sb, they are considered to pose a significant environmental risk. Given the hazardous nature of FCC spent catalysts, their demetallization and harmless treatment are extremely important. Currently, the most widely used methods for disposing of spent catalysts and recovering precious metals are pyrometallurgical and hydrometallurgical processes, but both of these methods suffer from high energy consumption and severe secondary pollution.

[0003] Bioleaching technology removes metals based on the metabolic activities of various bacteria. Compared with traditional wet and pyrometallurgical processes, bioleaching offers advantages such as environmental friendliness, low cost, simple operation and maintenance, mild treatment conditions, and no hazardous waste emissions. However, current research and attention on bioleaching for treating FCC waste catalysts are very limited, and the low metal leaching efficiency significantly restricts the widespread application of this technology. Furthermore, because FCC waste catalysts are rich in various highly toxic metals, existing bioleaching strains have poor tolerance to high concentrations of FCC waste catalysts, generally only achieving a removal effect on 1%-5% of the waste catalyst, greatly limiting the application of bioleaching technology. This study aims to improve the bioleaching efficiency of FCC waste catalysts by screening for microorganisms with high tolerance and high removal rates. Summary of the Invention

[0004] The purpose of this invention is to provide a strain of Acidithiobacillus caldus and a bacterial agent, as well as their applications in biometallurgy and bioleaching for the removal of metals from waste, and a method for the bioleaching removal of metals from waste. This strain can tolerate high doses of FCC waste catalyst, significantly higher than the 1%-5% waste catalyst addition of current strains, and has a significant removal effect on metals in FCC waste catalyst with an addition of 20% by weight.

[0005] To achieve the above objectives, the present invention provides a strain of Acidithiobacillus caldus, which has the accession number CCTCC No: M 2021709.

[0006] A second aspect of the present invention provides a microbial agent containing Acidithiobacillus caldus as described above.

[0007] A third aspect of the present invention provides the application of the thermophilic thiobacillus and / or the bacterial agent described above in biometallurgy.

[0008] The fourth aspect of the present invention provides the use of the thermophilic thiobacillus and / or the bacterial agent described above in the bioleaching removal of metals from waste.

[0009] The fifth aspect of the present invention provides a method for removing metals from waste by bioleaching, the method comprising: contacting the waste with the above-described Thiobacillus thermophilus and / or the above-described microbial agent.

[0010] The *Thiobacillus thermophilus* provided by this invention can tolerate high doses (up to 40% by weight) of FCC waste catalyst, which is significantly higher than the 1%-5% waste catalyst addition of current strains, and has a significant removal effect on metals (especially La and Ce) in FCC waste catalyst with an addition of 20% by weight.

[0011] This invention provides a usable bacterial strain for the removal of metals from FCC waste catalysts by bioleaching, and it is expected to enable the industrial application of bioleaching for the treatment of FCC waste catalysts.

[0012] Other features and advantages of the present invention will be described in detail in the following detailed description section.

[0013] Biological Preservation

[0014] The strain of this invention is Acidithiobacillus caldus UVS02, which was deposited on June 9, 2021, at the China Center for Type Culture Collection (address: Wuhan University, Wuhan, China, postcode: 430072) (abbreviation of depositary institution: CCTCC), with accession number CCTCC No: M 2021709. Detailed Implementation

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0016] The first aspect of this invention provides a strain of Acidithiobacillus caldus, which has the accession number CCTCC No: M 2021709.

[0017] The *Acidithiobacillus caldus* was deposited on June 9, 2021, at the China Center for Type Culture Collection (CCTCC, located at Luojia Mountain, Wuchang, Wuhan, 430072, China) with accession number CCTCC No: M 2021709.

[0018] A second aspect of the present invention provides a microbial agent containing Acidithiobacillus caldus as described above.

[0019] In this invention, the concentration of *Thiobacillus thermophilus* in the bacterial agent is not particularly limited and can be selected according to specific circumstances, for example, it can be 10... 8 CFU / g or higher.

[0020] Furthermore, depending on the intended use, the bacterial agent provided by this invention can be prepared into different dosage forms, and corresponding excipients and other components that will not affect the activity of the *Thiobacillus thermophilus* can be added. Specific selections are well known to those skilled in the art, and will not be described in detail here.

[0021] The bacterial agent is preferably a liquid bacterial agent.

[0022] The preparation method of the microbial agent can be a conventional preparation method in the art, such as that described in the fifth aspect.

[0023] A third aspect of the present invention provides the application of the thermophilic thiobacillus and / or the bacterial agent described above in biometallurgy.

[0024] The fourth aspect of the present invention provides the use of the thermophilic thiobacillus and / or the bacterial agent described above in the bioleaching removal of metals from waste.

[0025] The waste is preferably FCC spent catalyst.

[0026] The fifth aspect of the present invention provides a method for removing metals from waste by bioleaching, the method comprising: contacting the waste with the above-described Thiobacillus thermophilus and / or the above-described microbial agent.

[0027] Preferably, the thermophilic thiobacillus comes into contact with the waste in the form of an inoculant.

[0028] Preferably, the preparation method of the microbial agent includes: inoculating Thiobacillus thermophilus into a bioleaching medium to expand and obtain a seed liquid, and then inoculating the seed liquid into a bioleaching medium for fermentation to obtain the microbial agent.

[0029] In this invention, the bioleaching medium can be a conventionally used culture medium in the art. Preferably, the bioleaching medium contains: (NH4)2SO4 2-3 g / L, KH2PO4 2-4 g / L, MgSO4·7H2O 0.3-0.7 g / L, CaCl2 0.2-0.3 g / L, FeSO4 0.005-0.02 g / L, and sulfur powder 8-15 g / L; the pH of the bioleaching medium is 2.5-3.5.

[0030] Preferably, the conditions for the expansion culture include: a temperature of 40-45℃ and a time of 48-96h.

[0031] When the expansion culture is carried out in a shake flask, the rotation speed can be controlled at 100-150 rpm, preferably 120-135 rpm.

[0032] Preferably, the viable bacteria count in the seed liquid is 1×10⁻⁶. 8 cfu / mL or higher.

[0033] Preferably, the inoculation amount of the seed solution is 1-10% by volume.

[0034] Preferably, the fermentation conditions include: a temperature of 40-45℃, a time of 24-120 hours, and an aeration rate of 0.05-0.2 vvm. The stirring speed during the fermentation process is determined according to the volume of the fermentation tank, and can be adjusted by those skilled in the art based on actual conditions.

[0035] Preferably, the viable count of *Thiobacillus thermophilus* in the bacterial agent is 10. 8 cfu / mL or higher.

[0036] In this invention, the waste can be any waste containing metal, preferably FCC spent catalyst.

[0037] The amount of FCC waste catalyst added can be selected within a wide range. Preferably, the amount of FCC waste catalyst added is 150-200g compared to 1L of fermentation broth.

[0038] Preferably, the contact conditions include a temperature of 40-45°C and a contact time of 5-7 days.

[0039] The present invention will be described in detail below through embodiments.

[0040] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0041] Preparation method of biological leaching medium: Each 1000 mL of distilled water contains 2 g (NH4)2SO4, 3 g KH2PO4, 0.5 g MgSO4·7H2O, 0.01 g FeSO4·7H2O, and 0.25 g CaCl2·2H2O. Use 2 mol·L⁻¹ water... -1 Adjust the pH of the sulfuric acid solution to 3.0, autoclave at 115°C for 30 minutes, and then add 10g of sulfur powder that has been autoclaved for 2 hours.

[0042] Preparation method of solid culture medium: It is prepared by mixing three liquids, A, B, and C. Solution A: 100 mL of distilled water containing 0.6 g (NH₄)₂SO₄, 0.6 g KH₂PO₄, 0.1 g MgSO₄·7H₂O, and 0.05 g CaCl₂·2H₂O, autoclaved at 115℃ for 30 min; Solution B: 100 mL of distilled water with 2 g agar powder added, autoclaved at 115℃ for 30 min; Solution C: 10 mL of distilled water containing 2 g Na₂S₂O₃ and 0.006 g FeSO₄·7H₂O, filtered for sterilization. Solution A and Solution B are mixed when cooled to 80℃, then Solution C is added and mixed thoroughly. The mixture is poured into petri dishes and cooled to prepare the solid culture medium.

[0043] FCC spent catalyst was obtained from Sinopec Qingdao Refinery.

[0044] The metal content before and after bioleaching treatment was determined according to the determination method in "Determination of 22 Metallic Elements in Solid Waste by Inductively Coupled Plasma Atomic Emission Spectrometry (HJ 781-2016)".

[0045] Example 1

[0046] This embodiment is used to illustrate the screening of Thiobacillus thermophilus described in this invention.

[0047] (1) Screening of Thiobacillus thermophilus, which was obtained by the following methods:

[0048] The selected starting strain was *Thiobacillus thermophilus* (…). Acidithiobacillus caldus ).

[0049] Take 5 mL of the starting strain culture and place it in an irradiation dish. Irradiate the dish with UV lamps at 1000 lux, 1500 lux, and 2000 lux for 2 min–10 min, respectively. The concentration of the starting strain culture is 10. 5 per mL.

[0050] Prepare a bioleaching liquid culture medium, and add 80 mL of the bioleaching liquid culture medium and 20 g of FCC waste catalyst to a 250 mL Erlenmeyer flask to prepare a high-concentration FCC waste catalyst directional screening medium. Add the above-mentioned UV-mutated strains to the directional screening medium and culture them continuously at 45℃ and 130 rpm for 7-10 days.

[0051] Take the irradiated bacterial culture and dilute it 10. 4 -10 6 After dilution, take 100 μL of the diluted solution and spread it onto a solid culture medium plate. Incubate upside down at 37°C for 2-3 days, until colonies appear on the plate.

[0052] Colonies are picked and placed into a biological leaching liquid culture medium and cultured for 3-5 days. Then, the culture is diluted, spread onto a solid culture medium, cultured, and colonies are picked and cultured again to obtain a pure culture strain.

[0053] The mutagenized UVS02 was deposited at the China Center for Type Culture Collection (CCTCC) on June 9, 2021, with accession number CCTCC No:M 2021709.

[0054] Example 2

[0055] This embodiment is used to illustrate the performance evaluation of the *Thiobacillus thermophilus* described in this invention.

[0056] Bioleaching medium was prepared, and the starting strain and UVS02 were inoculated into the medium for shake flask and fermenter cultures, respectively. Shake flask culture conditions were 45℃, 130 rpm, and 72 h. Fermenter culture conditions were 45℃, 0.1 vvm aeration, and 96 h of continuous culture to obtain the bioleaching agent, which was used to treat FCC waste catalyst. The viable count of the bioleaching agent corresponding to each strain reached 10. 8 cfu / mL.

[0057] 20g of spent FCC catalyst and 80mL of bacterial culture were added to a 250mL Erlenmeyer flask, and cultured at 45℃ and 130rpm. After 7 days of continuous culture, the filtered spent FCC catalyst was collected, washed, dried, and its metal content was determined.

[0058] The removal of metals from FCC waste catalysts after treatment with different strains is shown in Table 1.

[0059] Table 1

[0060] <![CDATA[Metal content (mg·g -1 )]]> Ni V Sb La Ce Content in FCC spent catalyst 3.28 5.25 1.67 12.75 5.38 Content of the starting strain after treatment 2.98(9.1％) 4.09(22.1％) 1.35(19.1％) 9.56(25.0％) 4.86(9.7％) UVS02 content after treatment 1.59(51.5％) 2.35(55.2％) 0.27(83.8％) 2.99(76.5％) 1.64(69.5％)

[0061] Note: The numbers in parentheses indicate the metal removal rate.

[0062] Compared to the original strain, the strain UVS02 (accession number CCTCC No: M 2021709) described in this invention significantly improves the bioleaching efficiency of metals in FCC waste catalysts.

[0063] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A strain of thermophilic thiobacillus ( Acidithiobacillus caldus ), characterized in that, The preservation number of the Acidithiobacillus caldus is CCTCC No: M 2021709.

2. An inoculant characterized in that, The bacterial agent contains the thermophilic Sulfolobus bacteria according to claim 1 Acidithiobacillus caldus ).

3. The microbial agent of claim 2, wherein, The bacterial agent is a liquid bacterial agent.

4. The Acidithiobacillus caldus of claim 1 or the bacterial agent of claim 2 or 3 for use in bioleaching.

5. The Acidithiobacillus caldus of claim 1 or the bacterial agent of claim 2 or 3 for use in bioleaching of metals from waste.

6. A method for bioleaching metals from waste material, characterized in that, The method comprises: contacting the Acidithiobacillus caldus of claim 1 or the bacterial agent of claim 2 or 3 with the waste.

7. The method of claim 6, wherein, The Acidithiobacillus caldus is contacted with the waste in the form of a bacterial agent, and the preparation method of the bacterial agent comprises: inoculating the Acidithiobacillus caldus into a bioleaching culture medium to obtain a seed liquid, and then inoculating the seed liquid into the bioleaching culture medium to perform fermentation, so as to obtain the bacterial agent.

8. The method of claim 7, wherein, The bioleaching culture medium comprises: (NH4)2SO4 2-3 g / L, KH2PO4 2-4 g / L, MgSO4·7H2O 0.3-0.7 g / L, CaCl2 0.2-0.3 g / L, FeSO4 0.005-0.02 g / L, and sulfur powder 8-15 g / L; and the pH of the bioleaching culture medium is 2.5-3.

5.

9. The method of claim 7, wherein, The expansion culture is performed at a temperature of 40-45 ℃ for 48-96 h. The fermentation is performed at a temperature of 40-45 ℃ for 24-120 h, and the aeration amount is 0.05-0.2 vvm.

10. The method of claim 7, wherein, The viable cell number of the thermophilic sulfur-oxidizing bacteria in the bacterial agent is 10 8 cfu / mL or more.

11. The method of claim 6 or 7, wherein, The waste is an FCC waste catalyst.

12. The method of claim 11, wherein, The addition amount of the FCC waste catalyst is 150-200 g compared with 1 L of the bacterial agent.

13. The method of claim 12, wherein, The contacting is performed at a temperature of 40-45 ℃ for 5-7 days.