Biological treatment and recycling method for synchronous carbon removal and lithium enrichment of oil and gas field produced water

Abstract

The invention discloses a biological treatment and recycling method for synchronously removing carbon and enriching lithium from oil and gas field produced water, which comprises the following steps: 1) inoculating microorganisms into a liquid culture medium, and culturing to obtain a microorganism culture solution or culture; 2) directly adding and / or treating the microbial culture solution and / or culture obtained in the step 1) and then adding the microbial culture solution and / or culture into a reactor filled with oil and gas field produced water to be treated; (3) operating the reactor in the step (2), degrading organic matters in the oil and gas field produced water by microorganisms and enriching lithium ions; and 4) separating the microorganisms from the oil and gas field produced water, and extracting lithium ions enriched in the microorganisms. Wherein the microorganism is selected from one or a combination of more of the following microorganisms: staphylococcus saprophyticus, penicillium fistulosum, bacillus altitudinis, alternaria tenuissima and aspergillus sydowii. According to the method, recycling of lithium is achieved while oil and gas field produced water is recycled / discharged after reaching the standard, and the method has important significance on the national ecological environment and the new energy strategy.

Description

Technical Field

[0001] This invention belongs to the field of biological water treatment and resource utilization technology. Specifically, it is a biological treatment and resource utilization method for simultaneous carbon removal and lithium enrichment of produced water from oil and gas fields. Background Technology

[0002] With the accelerated global transition to clean energy, lithium's strategic importance as "white oil" is increasingly prominent. Traditional salt lake and hard rock lithium resources can no longer meet the explosive growth in market demand; therefore, the development of unconventional lithium resources has become a global focus. Produced water from oil and gas fields, as industrial wastewater rich in lithium resources, is gradually coming into focus. Studies show that produced water from many large oil and gas fields both domestically and internationally (such as the Sichuan Basin and the Permian Basin in the United States) contains high concentrations of lithium ions, with average lithium content exceeding the minimum industrial grade, making it valuable for development. The lithium concentration in some lithium-rich oil and gas field waters is even comparable to that of economically graded salt lake brine. This transforms produced water from wastewater requiring treatment into a highly valuable liquid lithium deposit.

[0003] However, the composition of produced water from oil and gas fields is extremely complex, posing a significant challenge to the utilization of its lithium resources. Besides lithium, the water typically contains high concentrations of organic matter (such as aromatic compounds, heterocyclic compounds, and hydrocarbons), high mineralization (total dissolved solids can reach tens to hundreds of thousands of mg / L), and various ions (such as Ca2+). 2+ Mg 2+ ).

[0004] Currently, the main treatment methods for produced water from oil and gas fields are formation reinjection, reuse, and compliant discharge. Regarding the latter, biological methods are widely studied and applied in the treatment of organic pollutants due to their advantages such as low treatment cost and environmental friendliness. Biological treatment processes often employ a combination of anaerobic and aerobic processes, utilizing functional microbial communities to degrade characteristic pollutants such as benzene, toluene, and phenols in produced water, achieving efficient carbon removal from oil and gas field produced water. Existing research papers and patents have not reported on the simultaneous removal of organic matter and enrichment of lithium ions for resource recovery through microbial treatment of produced water from oil and gas fields. Utilizing functional strains for simultaneous organic matter removal and lithium ion enrichment (simultaneous carbon removal and lithium enrichment) can help achieve lithium resource recovery while simultaneously reusing / complying for compliant discharge of produced water from oil and gas fields, which is of great significance to the national ecological environment and new energy strategy. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies in oil and gas field produced water treatment, which only focus on the degradation of organic matter and neglect the recovery of lithium resources, and to provide a biological treatment and resource recovery method that can simultaneously achieve efficient degradation of organic matter and selective enrichment of lithium ions.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for the simultaneous carbon removal and lithium enrichment of produced water from oil and gas fields through biological treatment and resource utilization, comprising the following steps:

[0007] Step 1: Inoculate the microorganisms into a liquid culture medium and culture them to obtain a microbial culture solution or culture;

[0008] Step 2: Add the microbial culture medium and / or culture obtained in Step 1 directly and / or add it after treatment to the reactor containing produced water from the oil and gas field to be treated;

[0009] Step 3: Run the reactor from Step 2, where microorganisms degrade organic matter in the produced water from the oil and gas field and enrich lithium ions;

[0010] Step 4: Separate the microorganisms from the produced water of the oil and gas field and extract the lithium ions enriched in the microorganisms;

[0011] The microorganisms are selected from one or more combinations of the following microorganisms: Staphylococcus saprophyticus, Penicillium steckii, Bacillus altitudinis, Alternaria tenuissima, and Aspergillus sydowii.

[0012] According to a preferred embodiment of the present invention, the Staphylococcus saprophyticus is Staphylococcus saprophyticus NCSL-YWH2, with accession number CGMCCNo.35847.

[0013] The Penicillium steckii species mentioned is Penicillium steckii NCSL-JXA6, with accession number CGMCC No.41831.

[0014] The Bacillus altitudinis mentioned is Bacillus altitudinis NCSL-CS2, with the accession number CGMCC No. 25665;

[0015] The Alternaria tenuissima mentioned is Alternaria tenuissima NCSL-XY7, with accession number CGMCC No.40313;

[0016] The Aspergillus sydowii species mentioned is Aspergillus sydowii NXY1, with accession number CGMCC No.40215.

[0017] Preferably, the liquid culture medium in step 1 consists of: carbon source 1-100 g / L, ammonium chloride 0.2-20 g / L, potassium dihydrogen phosphate 0.05-8 g / L, magnesium sulfate heptahydrate 0.2-5 g / L, lithium chloride 0-100 g / L, and sodium chloride 0-250 g / L.

[0018] The carbon source is selected from one or more of glucose, starch, sodium acetate, molasses, methanol, ethylene glycol, glycerol, and sucrose.

[0019] Preferably, the cultivation conditions in step 1 are: temperature 10-35℃, shaking speed 100-250 rpm, and cultivation time 1-10 days.

[0020] According to a preferred embodiment of the present invention, in step 2, the culture medium refers to the suspension culture medium obtained by suspending microorganisms in a liquid culture medium, and the culture refers to the mycelial ball culture obtained by spontaneously forming microorganisms in a liquid culture medium or the functional carrier culture with microorganisms attached obtained by adding a functional carrier for microorganism attachment culture.

[0021] Preferably, in step 2, the direct addition includes the direct addition of suspension culture, mycelial ball culture and / or functional carrier culture with attached microorganisms; the post-treatment addition includes adding the suspension culture after centrifugation concentration or immobilization treatment.

[0022] According to a preferred embodiment of the present invention, the produced water from the oil and gas field includes one or more combinations of oil field produced water, gas field produced water, shale gas produced water, tight gas produced water, oil field fracturing flowback fluid, shale gas fracturing flowback fluid, and simulated oil and gas field produced water; the COD of the produced water from the oil and gas field is 100 to 100,000 mg / L, and the lithium ion content is 0.1 to 2,000 mg / L.

[0023] Preferably, the organic compound in step 3 is one or more of hydrocarbons, alcohols, aldehydes, ketones, esters, phenols, surfactants, corrosion inhibitors, bactericides, or oil displacement agents;

[0024] The hydrocarbons are any one or more of aliphatic hydrocarbons, alkanes, or polycyclic aromatic hydrocarbons;

[0025] The alcohol is any one or more of methanol, ethylene glycol, or propanol;

[0026] The aldehyde is glutaraldehyde;

[0027] The ketones are any one or more of acetone or cyclohexanone;

[0028] The esters are any one or more of phthalates;

[0029] The phenols are any one or more of phenol or cresol.

[0030] According to a preferred embodiment of the present invention, the reactor described in step 2 or step 3 is one or more of the following: activated sludge reactor, biofilm reactor, biofilter, membrane bioreactor, and aerobic granular sludge reactor.

[0031] The reactor operates at a processing temperature of 10–35°C and an organic loading rate of 0.2–6.0 kg COD / (m³). 3 ·d).

[0032] Preferably, the method for extracting lithium ions enriched in microorganisms in step 4 is: natural release in a lithium-free environment, release induced by external ion addition, or release by cell disruption.

[0033] The added ions include H+ + Na + K + Ca 2+ Mg 2+ One or more of the following;

[0034] The methods for disrupting cells include one or more of the following: solid-phase shearing, liquid-phase shearing, acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis, organic solvent treatment, heat treatment, osmotic pressure shock, and repeated freeze-thaw cycles.

[0035] The present invention has the following beneficial effects:

[0036] 1. This invention is the first to utilize specific functional microorganisms to efficiently enrich lithium ions while degrading organic pollutants in produced water from oil and gas fields. This overcomes the shortcomings of traditional biological treatment processes that only focus on achieving emission standards while neglecting resource recovery, thus improving the overall efficiency of wastewater treatment.

[0037] 2. This invention uses a biological treatment method, which does not require the addition of chemical agents and causes no secondary pollution. Microorganisms can release lithium ions in a simple way. The process is simple, the operating cost is low, and it meets the requirements of green circular economy. It is suitable for large-scale treatment of produced water from various oil and gas fields and lithium resource recovery.

[0038] 3. The selected functional microorganisms have good adaptability to oil and gas field produced water with high salinity, high COD and complex organic matter composition. They have shown high COD removal rate (42% to 99%) and lithium recovery rate (10% to 98%) in different types of reactors (such as membrane bioreactors, biofilm reactors, etc.), and have a wide range of applications and high operational flexibility.

[0039] Preservation Matters

[0040] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this invention was deposited at the China General Microbiological Culture Collection Center (CGMCC) on September 9, 2025, with accession number CGMCCNo.35847.

[0041] The Penicillium steckii NCSL-JXA6 used in this invention was deposited at the China General Microbiological Culture Collection Center (CGMCC) on March 14, 2025, with accession number CGMCC No. 41831.

[0042] The Bacillus altitudinis NCSL-CS2 used in this invention was deposited at the China General Microbiological Culture Collection Center (CGMCC) on September 7, 2022, with accession number CGMCC No. 25665.

[0043] The Alternaria tenuissima NCSL-XY7 used in this invention was deposited at the China General Microbiological Culture Collection Center (CGMCC) on September 7, 2022, with accession number CGMCC No. 40313.

[0044] The Aspergillus sydowii NXY1 used in this invention was deposited at the China General Microbiological Culture Collection Center (CGMCC) on June 17, 2022, with accession number CGMCC No. 40215. Detailed Implementation

[0045] The present invention will be further described in detail below through specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0046] Unless otherwise specified, the experimental materials, operating methods, etc. used in the following embodiments can be obtained through conventional commercial channels, are known in the technical field, or are performed in accordance with the product instructions.

[0047] Example 1: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in simulated oil and gas field produced water system

[0048] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0049] The specific implementation steps are as follows:

[0050] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (1 g / L glucose, 0.2 g / L ammonium chloride, 0.05 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 0 g / L sodium chloride, and deionized water to a final volume of 1 L) in a clean bench and incubate at 10°C and 100 rpm for 1 day to obtain a 0.2 g / L microbial suspension.

[0051] Step 2: The microbial suspension culture obtained in Step 1 is directly added at an inoculum rate of 0.2 g / L (based on dry basis) to an activated sludge reactor (reactor system 1 L) containing simulated oil and gas field produced water (salinity 1 wt%, chemical oxygen demand (COD) concentration 100 mg / L, including hexadecane COD concentration 20 mg / L, propanol COD concentration 5 mg / L, glutaraldehyde COD concentration 1 mg / L, acetone COD concentration 9 mg / L, phthalate COD concentration 5 mg / L, phenol COD concentration 20 mg / L, surfactant petroleum sulfonate COD concentration 5 mg / L, PAM oil displacement agent COD concentration 35 mg / L, lithium ion concentration 0.1 mg / L).

[0052] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 0.2 kg COD / (m³). 3 •d), sludge age 4 days, pH maintained at 7.0-8.5, temperature maintained at 10℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0053] Step 4: After the reactor stabilizes and discharges sludge, 0.05 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field every day. The cells are placed in a shake flask containing 0.5 mL of deionized water, the pH is adjusted to 1.0 with hydrochloric acid, and the mixture is stirred at 30℃ and 160 rpm for 12 h. The cells are broken by acid hydrolysis to release the enriched lithium ions, and the supernatant is collected by filtration.

[0054] The specific results are as follows: After 12 days of operation, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 42%, the lithium recovery rate reached 98%, the intracellular lithium enrichment concentration reached 3.92 mg / g stem cells, and the extracted lithium ion concentration was 392 mg / L.

[0055] Example 2: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in simulated oil and gas field produced water system

[0056] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0057] The specific implementation steps are as follows:

[0058] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (1 g / L glucose, 0.2 g / L ammonium chloride, 0.05 g / L potassium dihydrogen phosphate, 0.2 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 0 g / L sodium chloride, and deionized water to a final volume of 1 L) in a clean bench and incubate at 10°C and 100 rpm for 1 day to obtain a 0.2 g / L microbial suspension.

[0059] Step 2: The microbial suspension culture obtained in Step 1 was directly added at an inoculum rate of 0.2 g / L (based on dry basis) to a biofilter reactor (reactor system 1 L) containing simulated oil and gas field produced water (salinity 1 wt%, chemical oxygen demand (COD) concentration 100 mg / L, including hexadecane COD concentration 20 mg / L, propanol COD concentration 5 mg / L, glutaraldehyde COD concentration 1 mg / L, acetone COD concentration 9 mg / L, phthalate COD concentration 5 mg / L, phenol COD concentration 20 mg / L, surfactant petroleum sulfonate COD concentration 5 mg / L, PAM oil displacement agent COD concentration 35 mg / L, lithium ion concentration 0.1 mg / L).

[0060] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 0.2 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 10℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0061] Step 4: The reactor is backwashed once every 10 days. The washed-off 0.5 g of biofilm (based on dry basis) is filtered and collected, and reacted in a muffle furnace at 600℃ for 6 h. The cells are then burned to ash using a heat treatment method.

[0062] The specific results are as follows: After 8 days of operation, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 65%, the average lithium recovery rate reached 25%, the average intracellular lithium enrichment concentration reached 1 mg / g stem cells, and the lithium ion content in the ash was 10 mg / g.

[0063] Example 3: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in simulated oil and gas field produced water system

[0064] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0065] The specific implementation steps are as follows:

[0066] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (100 g / L glucose, 20 g / L ammonium chloride, 8 g / L potassium dihydrogen phosphate, 5 g / L magnesium sulfate heptahydrate, 100 g / L lithium chloride, 0 g / L sodium chloride, and deionized water to a final volume of 1 L) in a clean bench and incubate at 35°C and 250 rpm for 10 days to obtain a 20 g / L microbial suspension.

[0067] Step 2: The microbial suspension culture obtained in Step 1 was directly added at an inoculum rate of 2 g / L (based on dry basis) to an aerobic granular sludge reactor (reactor system 5 L) containing simulated oil and gas field produced water (salinity 10 wt%, chemical oxygen demand (COD) concentration 100,000 mg / L, including dodecane COD concentration 20,000 mg / L, ethylene glycol COD concentration 5,000 mg / L, glutaraldehyde COD concentration 1,000 mg / L, cyclohexanone COD concentration 9,000 mg / L, phthalate COD concentration 5,000 mg / L, cresol COD concentration 20,000 mg / L, surfactant petroleum sulfonate COD concentration 3,000 mg / L, amine corrosion inhibitor COD concentration 2,000 mg / L, PAM oil displacement agent COD concentration 35,000 mg / L, lithium ion concentration 2,000 mg / L).

[0068] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 16.7 days and an organic loading of 6.0 kg COD / (m³). 3 •d), sludge age 12 days, pH maintained at 7.0-8.5, temperature maintained at 35℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0069] Step 4: After the reactor stabilizes and discharges sludge, 5 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field daily. The particles are crushed by a pulverizer, and the cells are broken up by solid-phase shearing to release the enriched lithium ions. The supernatant is then filtered and collected.

[0070] The specific results are as follows: After 40 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 12 g / L, the COD removal rate reached 70%, the lithium recovery rate reached 10%, the intracellular lithium enrichment concentration reached 11.98 mg / g stem cells, and the extracted lithium ion concentration was 1030 mg / L.

[0071] Example 4: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in the produced water system of an oilfield in Northeast China

[0072] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0073] The specific implementation steps are as follows:

[0074] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into 5 L of liquid culture medium (starch 10 g / L, ammonium chloride 1 g / L, potassium dihydrogen phosphate 1 g / L, magnesium sulfate heptahydrate 0.5 g / L, lithium chloride 0 g / L, sodium chloride 30 g / L, and deionized water to make up the volume) in a clean bench and incubate at 30℃ and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0075] Step 2: Immobilize the microbial suspension obtained in Step 1 by embedding (the microbial suspension is centrifuged at 3000 rpm for 5 minutes to obtain a mixed liquid suspended solids concentration (MLSS) of approximately 2 × 10⁻⁶). 4 The concentrated bacterial solution of mg / L was added to 3% sodium alginate solution and stirred evenly. Then, it was dripped into 4% calcium chloride solution through a peristaltic pump for cross-linking for 4 h. The encapsulated particles were added to a sequencing batch reactor (reactor system 2 L) containing produced water from an oilfield in Northeast China (salinity 1 wt%, chemical oxygen demand COD concentration 700 mg / L, lithium ion concentration 14 mg / L).

[0076] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 16.8 h, a water exchange ratio of 100%, and an organic loading rate of 1.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0077] Step 4: Remove the encapsulated particles each time the water is changed, and place them in a shake flask containing deionized water (250 mL Erlenmeyer flask, 100 mL volume). Adjust the pH to 5.0 with hydrochloric acid, and shake at 30℃ and 160 rpm for 12 h. Utilize added H₂... + The enriched lithium ions are induced to be released, the supernatant is filtered and the encapsulated particles that have been released are returned to the reactor for further carbon removal and lithium enrichment.

[0078] The specific results are as follows: After 20 days of reactor operation, the microbial equivalent of the encapsulated particles reached about 10 g / L, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 69%, the lithium recovery rate reached 55%, the intracellular lithium enrichment concentration reached 0.77 mg / g stem cells, the extracted lithium ion concentration was 135 mg / L, and the total lithium recovery rate was 48.2%.

[0079] Example 5: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in the produced water system of an oilfield in Northeast China

[0080] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0081] The specific implementation steps are as follows:

[0082] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into 5 L of liquid culture medium (starch 10 g / L, ammonium chloride 1 g / L, potassium dihydrogen phosphate 1 g / L, magnesium sulfate heptahydrate 0.5 g / L, lithium chloride 0 g / L, sodium chloride 30 g / L, and deionized water to make up the volume) in a clean bench and incubate at 30℃ and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0083] Step 2: Immobilize the microbial suspension obtained in Step 1 by embedding (the microbial suspension is centrifuged at 3000 rpm for 5 minutes to obtain a mixed liquid suspended solids concentration (MLSS) of approximately 2 × 10⁻⁶). 4 The concentrated bacterial solution of mg / L was added to 3% sodium alginate solution and stirred evenly. Then, it was dripped into 4% calcium chloride solution through a peristaltic pump for cross-linking for 4 h. The encapsulated particles were added to a sequencing batch reactor (reactor system 2 L) containing produced water from an oilfield in Northeast China (salinity 1 wt%, chemical oxygen demand COD concentration 700 mg / L, lithium ion concentration 14 mg / L).

[0084] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 16.8 h, a water exchange ratio of 100%, and an organic loading rate of 1.0 kg COD / (m³). 3•d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0085] Step 4: Remove the embedded particles each time the water is changed and place them in a shake flask containing 10 g / L NaCl solution (250 mL Erlenmeyer flask, 100 mL volume). Shake at 30°C and 160 rpm for 12 h, utilizing the added NaCl solution. + The enriched lithium ions are induced to be released, the supernatant is filtered and the encapsulated particles that have been released are returned to the reactor for further carbon removal and lithium enrichment.

[0086] The specific results are as follows: After 20 days of reactor operation, the microbial equivalent of the encapsulated particles reached about 10 g / L, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 75%, the lithium recovery rate reached 70%, the intracellular lithium enrichment concentration reached 0.98 mg / g stem cells, the extracted lithium ion concentration was 180 mg / L, and the total lithium recovery rate was 64.3%.

[0087] Example 6: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in a shale gas produced water system in Sichuan Province

[0088] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0089] The specific implementation steps are as follows:

[0090] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into 5 L of liquid culture medium (sodium acetate 10 g / L, ammonium chloride 1 g / L, potassium dihydrogen phosphate 1 g / L, magnesium sulfate heptahydrate 0.5 g / L, lithium chloride 0 g / L, sodium chloride 30 g / L, and deionized water to make up the volume) in a clean bench, and incubate at 30℃ and 160 rpm for 2 days to obtain a 2 g / L microbial suspension culture.

[0091] Step 2: Immobilize the microbial suspension obtained in Step 1 by embedding (the microbial suspension is centrifuged at 3000 rpm for 5 minutes to obtain a mixed liquid suspended solids concentration (MLSS) of approximately 2 × 10⁻⁶). 4The concentrated bacterial solution of mg / L was added to 3% sodium alginate solution and stirred evenly. Then, it was dripped into 4% calcium chloride solution via a peristaltic pump for cross-linking for 4 h. The encapsulated particles were added to a sequencing batch reactor (reactor system 2 L) containing produced water from a shale gas mine in Sichuan (salinity 3 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 32 mg / L).

[0092] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h, a water exchange ratio of 100%, and an organic load of 1.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0093] Step 4: Remove the embedded particles each time the water is changed and place them in a shake flask containing 5 g / L MgCl2 solution (250 mL Erlenmeyer flask, 100 mL volume). Shake at 30°C and 160 rpm for 12 h. Utilize the added Mg... 2+ The enriched lithium ions are induced to be released, the supernatant is filtered and the encapsulated particles that have been released are returned to the reactor for further carbon removal and lithium enrichment.

[0094] The specific results are as follows: After 18 days of reactor operation, the microbial equivalent of the encapsulated particles reached about 10 g / L, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 52%, the lithium recovery rate reached 66%, the intracellular lithium enrichment concentration reached 2.112 mg / g stem cells, the extracted lithium ion concentration was 380 mg / L, and the total lithium recovery rate was 59.38%.

[0095] Example 7: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in a tight gas produced water system in the Ordos Basin.

[0096] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0097] The specific implementation steps are as follows:

[0098] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into 5 L of liquid culture medium (molasses 10 g / L, ammonium chloride 1 g / L, potassium dihydrogen phosphate 1 g / L, magnesium sulfate heptahydrate 0.5 g / L, lithium chloride 0 g / L, sodium chloride 30 g / L, and deionized water to make up the volume) in a clean bench, and incubate at 30℃ and 160 rpm for 2 days to obtain a 2 g / L microbial suspension culture.

[0099] Step 2: Immobilize the microbial suspension obtained in Step 1 by embedding (the microbial suspension is centrifuged at 3000 rpm for 5 minutes to obtain a mixed liquid suspended solids concentration (MLSS) of approximately 2 × 10⁻⁶). 4 A concentrated bacterial solution of mg / L was added to a 3% sodium alginate solution and stirred until homogeneous. Then, the solution was dripped into a 4% calcium chloride solution via a peristaltic pump for cross-linking for 4 hours. The encapsulated particles were added to a sequencing batch reactor (reactor system 2 L) containing tight gas produced water from a certain area of ​​the Ordos Basin (salinity 3.5 wt%, COD concentration 2000 mg / L, lithium ion concentration 6 mg / L).

[0100] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h, a water exchange ratio of 100%, and an organic load of 4.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0101] Step 4: Remove the embedded particles each time the water is changed and place them in a shake flask containing 10 g / L KCl solution (250 mL Erlenmeyer flask, 100 mL volume). Shake at 30°C and 160 rpm for 12 h, utilizing the added KCl solution. + The enriched lithium ions are induced to be released, the supernatant is filtered and the encapsulated particles that have been released are returned to the reactor for further carbon removal and lithium enrichment.

[0102] The specific results are as follows: After 20 days of reactor operation, the microbial equivalent of the encapsulated particles reached about 10 g / L, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 68%, the lithium recovery rate reached 82%, the intracellular lithium enrichment concentration reached 0.492 mg / g stem cells, the extracted lithium ion concentration was 90.8 mg / L, and the total lithium recovery rate was 75.67%.

[0103] Example 8: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in the fracturing flowback fluid system of an oilfield in Inner Mongolia.

[0104] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0105] The specific implementation steps are as follows:

[0106] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into 5 L of liquid culture medium (10 g / L glycerol, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and deionized water to make up the volume) in a clean bench, and incubate at 30℃ and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0107] Step 2: Immobilize the microbial suspension obtained in Step 1 by embedding (the microbial suspension is centrifuged at 3000 rpm for 5 minutes to obtain a mixed liquid suspended solids concentration (MLSS) of approximately 2 × 10⁻⁶). 4 A concentrated bacterial solution of mg / L was added to a 3% sodium alginate solution and stirred until homogeneous. The solution was then dripped into a 4% calcium chloride solution via a peristaltic pump for cross-linking for 4 hours. The encapsulated particles were added to a sequencing batch reactor (reactor system 2 L) containing fracturing flowback fluid from an oilfield in Inner Mongolia (salinity 3wt%, COD concentration 3500 mg / L, lithium ion concentration 0.8 mg / L).

[0108] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 84 h, a water exchange ratio of 100%, and an organic load of 1.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0109] Step 4: Remove the embedded particles each time the water is changed and place them in a shake flask containing 10 g / L CaCl2 solution (250 mL Erlenmeyer flask, 100 mL volume). Shake at 30°C and 160 rpm for 12 h, utilizing the added Ca... 2+The enriched lithium ions are induced to be released, the supernatant is filtered and the encapsulated particles that have been released are returned to the reactor for further carbon removal and lithium enrichment.

[0110] The specific results are as follows: After 20 days of reactor operation, the microbial equivalent of the encapsulated particles reached about 10 g / L, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 70%, the lithium recovery rate reached 85%, the intracellular lithium enrichment concentration reached 0.068 mg / g stem cells, the extracted lithium ion concentration was 13 mg / L, and the total lithium recovery rate was 69.06%.

[0111] Example 9: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in a shale gas fracturing flowback fluid system in Sichuan.

[0112] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0113] The specific implementation steps are as follows:

[0114] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (10 g / L sucrose, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and deionized water to a final volume of 1 L) in a clean bench and incubate at 30°C and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0115] Step 2: The microbial suspension culture obtained in Step 1 is concentrated by centrifugation (the microbial suspension culture is centrifuged at 8000 rpm for 5 minutes), and added at an inoculum rate of 4 g / L (based on dry basis) to an aerobic granular sludge reactor (reactor system 0.5 L) containing flowback fluid from a shale gas fracturing plant in Sichuan (salinity 2.3 wt%, chemical oxygen demand (COD) concentration 1332 mg / L, lithium ion concentration 30 mg / L).

[0116] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 2.6 kg COD / (m³). 3 •d), sludge age 30 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0117] Step 4: After the reactor stabilizes and discharges sludge, 0.25 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field every day. The cells are placed in a shake flask containing 10 mL of deionized water and ultrasonically broken for 30 min. The cells are broken by liquid phase shearing to release the enriched lithium ions. The supernatant is then filtered and collected.

[0118] The specific results are as follows: After 50 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 15 g / L, the COD removal rate reached 58%, the lithium recovery rate reached 34%, the intracellular lithium enrichment concentration reached 40.8 mg / g stem cells, and the extracted lithium ion concentration was 920 mg / L.

[0119] Example 10: Application of Simultaneous Carbon Removal and Lithium Enrichment Technology of Staphylococcus saprophyticus NCSL-YWH2 in Produced Water Systems of Mixed Oil and Gas Fields

[0120] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0121] The specific implementation steps are as follows:

[0122] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (5 g / L glucose, 5 g / L sucrose, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and add deionized water to a final volume of 1 L) in a clean bench and incubate at 30°C and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0123] Step 2: The microbial suspension culture obtained in Step 1 is directly added at an inoculum rate of 2 g / L (based on dry basis) to an aerobic granular sludge reactor (reactor system 1 L) containing mixed oil and gas field produced water (shale gas produced water in Example 6 and shale gas fracturing flowback fluid in Example 9 are mixed at a ratio of 1:1, with a salinity of 2.7 wt%, a chemical oxygen demand (COD) concentration of 916 mg / L, and a lithium ion concentration of 31 mg / L).

[0124] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 1.8 kg COD / (m³).3 •d), sludge age 20 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0125] Step 4: After the reactor stabilizes and discharges sludge, 0.4 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field every day. The cells are placed in a shake flask containing 10 mL of deionized water, the pH is adjusted to 13.0 with sodium hydroxide, and the mixture is carried out at 30℃ and 160 rpm for 12 h. The cells are broken by alkaline hydrolysis to release the enriched lithium ions, and the supernatant is collected by filtration.

[0126] The specific results are as follows: After 40 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 8 g / L, the COD removal rate reached 70%, the lithium recovery rate reached 50%, the intracellular lithium enrichment concentration reached 77.5 mg / g stem cells, and the extracted lithium ion concentration was 3000 mg / L.

[0127] Example 11: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in the produced water system of a gas field in Xinjiang

[0128] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0129] The specific implementation steps are as follows:

[0130] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (ethylene glycol 10 g / L, ammonium chloride 1 g / L, potassium dihydrogen phosphate 1 g / L, magnesium sulfate heptahydrate 0.5 g / L, lithium chloride 0 g / L, sodium chloride 250 g / L, and deionized water to a final volume of 1 L) in a clean bench and incubate at 30℃ and 160 rpm for 10 days to obtain a 2 g / L microbial suspension.

[0131] Step 2: The microbial suspension culture obtained in Step 1 was directly added at an inoculum rate of 2 g / L (based on dry basis) to a biofilm reactor (reactor system 1 L) containing produced water from a gas field in Xinjiang (salinity 20 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 34 mg / L).

[0132] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 1.0 kg COD / (m³). 3 •d), sludge age 12 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0133] Step 4: After the reactor stabilizes and discharges sludge, 0.2 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field every day. The cells are placed in a shake flask containing 10 mL of deionized water, and 0.1% polysaccharide enzyme is added. The mixture is stirred at 30℃ and 160 rpm for 12 h to break the cells and release the enriched lithium ions. The supernatant is then filtered and collected.

[0134] The specific results are as follows: After 30 days of operation, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 70%, the lithium recovery rate reached 48%, the intracellular lithium enrichment concentration reached 163.2 mg / g stem cells, and the extracted lithium ion concentration was 4512 mg / L.

[0135] Example 12: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in the produced water system of a gas field in Xinjiang

[0136] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0137] The specific implementation steps are as follows:

[0138] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (10 g / L glucose, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 100 g / L sodium chloride, and add deionized water to a final volume of 1 L) in a clean bench and incubate at 30°C and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0139] Step 2: The microbial suspension culture obtained in Step 1 is directly added at an inoculum rate of 2 g / L (based on dry basis) to an aerobic granular sludge reactor (reactor system 1 L) containing produced water from a gas field in Xinjiang (salinity 10 wt%, chemical oxygen demand COD concentration 1000 mg / L, lithium ion concentration 50 mg / L).

[0140] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 2.0 kg COD / (m³). 3 •d), sludge age 20 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0141] Step 4: After the reactor stabilizes and discharges sludge, 0.4 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field every day. The cells are placed in a shake flask containing 10 mL of 10% (v / v) butanol solution and mixed at 30°C and 160 rpm for 12 h. The cells are broken up by organic solvent treatment to release the enriched lithium ions. The supernatant is then filtered and collected.

[0142] The specific results are as follows: After 35 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 8 g / L, the COD removal rate reached 48%, the lithium recovery rate reached 50%, the intracellular lithium enrichment concentration reached 125 mg / g stem cells, and the extracted lithium ion concentration was 4930 mg / L.

[0143] Example 13: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 in the produced water system of a gas field in Xinjiang

[0144] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0145] The specific implementation steps are as follows:

[0146] Step 1: Inoculate the Staphylococcus saprophyticus NCSL-YWH2 preservation tube into liquid culture medium (10 g / L glucose, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 100 g / L sodium chloride, and add deionized water to a final volume of 1 L) in a clean bench and incubate at 30°C and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0147] Step 2: The microbial suspension culture obtained in Step 1 is directly added at an inoculum rate of 2 g / L (based on dry basis) to an aerobic granular sludge reactor (reactor system 1 L) containing produced water from a gas field in Xinjiang (salinity 10 wt%, chemical oxygen demand COD concentration 1000 mg / L, lithium ion concentration 50 mg / L).

[0148] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 2.0 kg COD / (m³). 3 •d), sludge age 20 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0149] Step 4: After the reactor stabilizes and discharges sludge, 0.4 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field daily. The cells are placed in a shake flask containing 10 mL of 100 g / L glucose solution and mixed at 30°C and 160 rpm for 2 hours. After filtration, the cells are placed in a shake flask containing 10 mL of deionized water and mixed at 30°C and 160 rpm for 2 hours. The mixture is then frozen at -80°C for 2 hours and thawed at 30°C. This process is repeated 3 to 5 times to break the cells and release the enriched lithium ions using osmotic pressure shock and repeated freeze-thaw cycles. The supernatant is then filtered and collected.

[0150] The specific results are as follows: After 35 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 8 g / L, the COD removal rate reached 48%, the lithium recovery rate reached 50%, the intracellular lithium enrichment concentration reached 125 mg / g stem cells, and the extracted lithium ion concentration was 4285 mg / L.

[0151] Example 14: Application of simultaneous carbon removal and lithium enrichment technology of Penicillium steckii NCSL-JXA6 in the produced water system of a gas field in Xinjiang

[0152] The *Penicillium steckii* NCSL-JXA6 used in this embodiment was deposited on March 14, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCCNo.41831.

[0153] The specific implementation steps are as follows:

[0154] Step 1: Prepare a suspension of Penicillium steckii NCSL-JXA6 fungal spores (10... 5 (Spores / mL) were inoculated in a clean bench into liquid culture medium (100 g / L glucose, 20 g / L ammonium chloride, 8 g / L potassium dihydrogen phosphate, 5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 250 g / L sodium chloride, and deionized water was added to bring the volume to 1 L), and cultured at 30℃ and 250 rpm for 3 days to obtain 15 g / L mycelial ball culture;

[0155] Step 2: The mycelial ball culture obtained in Step 1 was directly added to a membrane bioreactor (reactor system 6 L) containing produced water from a gas field in Xinjiang (salinity 20 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 34 mg / L) at an inoculation rate of 2 g / L (based on dry basis).

[0156] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 6 h and an organic loading of 2.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0157] Step 4: Every 6 hours, 4 g (based on dry basis) of microorganisms are filtered and separated from the produced water of the oil and gas field, placed in a shake flask containing 10 mL of deionized water, and shaken at 30°C and 160 rpm for 12 hours. The microorganisms naturally release the enriched lithium ions. The supernatant is filtered and the released microorganisms are returned to the reactor for further carbon removal and lithium enrichment.

[0158] The specific results are as follows: After 20 days of operation, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 99%, the lithium recovery rate reached 10%, the intracellular lithium enrichment concentration reached 5.1 mg / g stem cells, and the extracted lithium ion concentration was 1200 mg / L.

[0159] Example 15: Application of simultaneous carbon removal and lithium enrichment technology of Penicillium steckii NCSL-JXA6 in the produced water system of a gas field in Xinjiang

[0160] The *Penicillium steckii* NCSL-JXA6 used in this embodiment was deposited on March 14, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCCNo.41831.

[0161] The specific implementation steps are as follows:

[0162] Step 1: Inoculate the *Penicillium steckii* NCSL-JXA6 preservation tubes into liquid culture medium (20 g / L glucose, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 250 g / L sodium chloride, and bring the volume to 1 L with deionized water) in a clean bench. Add 27 cm³ of the medium to the culture medium. 3 Fifteen pieces of polyurethane packing were incubated at 30℃ and 250 rpm for 3 days to obtain a 4 g / L functional carrier culture with attached microorganisms.

[0163] Step 2: The functional carrier culture with attached microorganisms obtained in Step 1 was directly added at an inoculum rate of 2 g / L (based on dry microbial substrate) to a sequencing batch biofilm reactor (reactor system 2 L) containing produced water from a gas field in Xinjiang (salinity 20 wt%, chemical oxygen demand COD concentration 200 mg / L, lithium ion concentration 34 mg / L).

[0164] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 6 hours, a water exchange ratio of 100%, and an organic load of 0.8 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0165] Step 4: All the functional carrier cultures with attached microorganisms are filtered and separated from the produced water of the oil and gas field during each water change. They are placed in a shake flask containing 200 mL of deionized water and shaken at 30℃ and 160 rpm for 12 h. The microorganisms will naturally release the enriched lithium ions. The supernatant is filtered and the released microorganisms are returned to the reactor for further carbon removal and lithium enrichment.

[0166] The specific results are as follows: After 20 days of reactor operation, the carrier microbial equivalent reached about 5 g / L, the biological carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 99%, the lithium recovery rate reached 24%, the intracellular lithium enrichment concentration reached 1.63 mg / g stem cells, and the extracted lithium ion concentration was 65 mg / L.

[0167] Example 16: Application of Penicillium steckii NCSL-JXA6 in Simulated Oil and Gas Field Produced Water System for Simulated Carbon Removal and Lithium Enrichment

[0168] The *Penicillium steckii* NCSL-JXA6 used in this embodiment was deposited on March 14, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCCNo.41831.

[0169] The specific implementation steps are as follows:

[0170] Step 1: Inoculate the *Penicillium steckii* NCSL-JXA6 inoculum tubes in a clean bench into liquid culture medium (10 g / L glucose, 10 g / L methanol, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 250 g / L sodium chloride, and bring the volume to 1 L with deionized water). Add 27 cm³ of the medium to the inoculum. 3 Fifteen pieces of polyurethane packing were incubated at 30℃ and 250 rpm for 3 days to obtain a 4 g / L functional carrier culture with attached microorganisms.

[0171] Step 2: The functional carrier culture with attached microorganisms obtained in Step 1 is directly added at an inoculum rate of 2 g / L (based on dry basis) to a sequencing batch biofilm reactor (reactor system 2 L) containing simulated oil and gas field produced water (salinity 20 wt%, chemical oxygen demand (COD) concentration 500 mg / L, including naphthalene COD concentration 200 mg / L, methanol COD concentration 200 mg / L, chlorhexidine bactericide COD concentration 100 mg / L, and lithium ion concentration 50 mg / L).

[0172] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h, a water exchange ratio of 100%, and an organic load of 1.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0173] Step 4: All the functional carrier cultures with attached microorganisms are filtered and separated from the produced water of the oil and gas field during each water change. They are placed in a shake flask containing 200 mL of deionized water and shaken at 30℃ and 160 rpm for 12 h. The microorganisms will naturally release the enriched lithium ions. The supernatant is filtered and the released microorganisms are returned to the reactor for further carbon removal and lithium enrichment.

[0174] The specific results are as follows: After 30 days of reactor operation, the carrier microbial equivalent reached about 5 g / L, the biological carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 90%, the lithium recovery rate reached 22%, the intracellular lithium enrichment concentration reached 2.2 mg / g stem cells, and the extracted lithium ion concentration was 96 mg / L.

[0175] Example 17: Application of simultaneous carbon removal and lithium enrichment technology of Bacillus altitudinis NCSL-CS2 in the produced water system of an oilfield in Northeast China

[0176] The Bacillus altitudinis NCSL-CS2 used in this embodiment was deposited on September 7, 2022, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 25665.

[0177] The specific implementation steps are as follows:

[0178] Step 1: Inoculate the Bacillus altitudinis NCSL-CS2 preservation tubes into 5 L of liquid culture medium (10 g / L glucose, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and deionized water to make up the volume) in a clean bench, and incubate at 30℃ and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0179] Step 2: Immobilize the microbial suspension obtained in Step 1 by embedding (the microbial suspension is centrifuged at 3000 rpm for 5 minutes to obtain a mixed liquid suspended solids concentration (MLSS) of approximately 2 × 10⁻⁶). 4 The concentrated bacterial solution of mg / L was added to 3% sodium alginate solution and stirred evenly. Then, it was dripped into 4% calcium chloride solution through a peristaltic pump for cross-linking for 4 h. The encapsulated particles were added to a sequencing batch reactor (reactor system 2 L) containing produced water from an oilfield in Northeast China (salinity 3 wt%, chemical oxygen demand COD concentration 700 mg / L, lithium ion concentration 14 mg / L).

[0180] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 16.8 h, a water exchange ratio of 100%, and an organic loading rate of 1.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0181] Step 4: Remove the embedded particles each time the water is changed and place them in a shake flask containing 10 g / L NaCl solution (250 mL Erlenmeyer flask, 100 mL volume). Shake at 30°C and 160 rpm for 12 h, utilizing the added NaCl solution. + The enriched lithium ions are induced to be released, the supernatant is filtered and the encapsulated particles that have been released are returned to the reactor for further carbon removal and lithium enrichment.

[0182] The specific results are as follows: After 20 days of reactor operation, the microbial equivalent of the encapsulated particles reached about 10 g / L, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 95%, the lithium recovery rate reached 35%, the intracellular lithium enrichment concentration reached 0.49 mg / g stem cells, the extracted lithium ion concentration was 81 mg / L, and the total lithium recovery rate was 28.93%.

[0183] Example 18: Application of simultaneous carbon removal and lithium enrichment technology of Alternaria tenuissima NCSL-XY7 in a shale gas produced water system in Sichuan Province.

[0184] The Alternaria tenuissima NCSL-XY7 used in this embodiment was deposited on September 7, 2022, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCCNo.40313.

[0185] The specific implementation steps are as follows:

[0186] Step 1: Prepare a suspension of Alternaria tenuissima NCSL-XY7 fungal spores (10... 5 (Spores / mL) were inoculated in a clean bench into liquid culture medium (100 g / L glucose, 20 g / L ammonium chloride, 8 g / L potassium dihydrogen phosphate, 5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and deionized water was added to bring the volume to 1 L), and cultured at 30℃ and 250 rpm for 3 days to obtain 15 g / L mycelial ball culture;

[0187] Step 2: The mycelial ball culture obtained in Step 1 was directly added to a sequencing batch reactor (reactor system 6 L) containing produced water from a shale gas mine in Sichuan (salinity 3 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 32 mg / L).

[0188] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 1.0 kg COD / (m³). 3•d), sludge age 10 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0189] Step 4: After the reactor stabilizes and discharges sludge, 1.2 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field daily. The particles are crushed by a pulverizer, and the cells are broken up by solid-phase shearing to release the enriched lithium ions. The supernatant is then filtered and collected.

[0190] The specific results are as follows: After 20 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 2 g / L, the COD removal rate reached 90%, the lithium recovery rate reached 10%, the intracellular lithium enrichment concentration reached 32 mg / g stem cells, and the extracted lithium ion concentration was 2600 mg / L.

[0191] Example 19: Application of Simultaneous Carbon Removal and Lithium Enrichment Technology of Aspergillus sydowii NXY1 in a Shale Gas Produced Water System in Sichuan

[0192] The Aspergillus sydowii NXY1 used in this embodiment was deposited on June 17, 2022, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 40215.

[0193] The specific implementation steps are as follows:

[0194] Step 1: Prepare a suspension of Aspergillus sydowii NXY1 fungal spores (10... 5 (Spores / mL) were inoculated in a clean bench into liquid culture medium (100 g / L glucose, 20 g / L ammonium chloride, 8 g / L potassium dihydrogen phosphate, 5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and deionized water to a final volume of 1 L), and cultured at 30°C and 250 rpm for 3 days to obtain 15 g / L mycelial ball culture;

[0195] Step 2: The mycelial ball culture obtained in Step 1 was directly added to a sequencing batch reactor (reactor system 6 L) containing produced water from a shale gas mine in Sichuan (salinity 3 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 32 mg / L).

[0196] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 1.0 kg COD / (m³). 3•d), sludge age 10 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0197] Step 4: After the reactor stabilizes and discharges sludge, 1.8 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field daily. The particles are crushed by a pulverizer, and the cells are broken up by solid-phase shearing to release the enriched lithium ions. The supernatant is then filtered and collected.

[0198] The specific results are as follows: After 16 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 3 g / L, the COD removal rate reached 99%, the lithium recovery rate reached 23%, the intracellular lithium enrichment concentration reached 49.1 mg / g stem cells, and the extracted lithium ion concentration was 4215 mg / L.

[0199] Example 20: Application of Simultaneous Carbon Removal and Lithium Enrichment Technology of Aspergillus sydowii NXY1 in Produced Water System of an Oil and Gas Field in Xinjiang

[0200] The Aspergillus sydowii NXY1 used in this embodiment was deposited on June 17, 2022, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 40215.

[0201] The specific implementation steps are as follows:

[0202] Step 1: Prepare a suspension of Aspergillus sydowii NXY1 fungal spores (10... 5 (Spores / mL) were inoculated in a clean bench into liquid culture medium (100 g / L glucose, 20 g / L ammonium chloride, 8 g / L potassium dihydrogen phosphate, 5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and deionized water to a final volume of 1 L), and cultured at 30°C and 250 rpm for 3 days to obtain 15 g / L mycelial ball culture;

[0203] Step 2: The mycelial ball culture obtained in Step 1 was directly added to a sequencing batch aerobic granular sludge reactor (reactor system 6 L) containing produced water from an oil and gas field in Xinjiang (salinity 10 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 63 mg / L).

[0204] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 1.0 kg COD / (m³). 3•d), sludge age 30 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0205] Step 4: After the reactor stabilizes and discharges sludge, 1.2 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field daily. The particles are crushed by a pulverizer, and the cells are broken up by solid-phase shearing to release the enriched lithium ions. The supernatant is then filtered and collected.

[0206] The specific results are as follows: After 36 days of operation, the biological carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 6 g / L, the COD removal rate reached 96%, the lithium recovery rate reached 12%, the intracellular lithium enrichment concentration reached 75.6 mg / g stem cells, and the extracted lithium ion concentration was 4681 mg / L.

[0207] Example 21: Application of simultaneous carbon removal and lithium enrichment technology of Staphylococcus saprophyticus NCSL-YWH2 and Penicillium steckii NCSL-JXA6 in the produced water system of a gas field in Xinjiang.

[0208] The *Staphylococcus saprophyticus* NCSL-YWH2 used in this embodiment was deposited on September 9, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No. 35847.

[0209] The *Penicillium steckii* NCSL-JXA6 used in this embodiment was deposited on March 14, 2025, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCCNo.41831.

[0210] The specific implementation steps are as follows:

[0211] Step 1: Prepare a suspension of Staphylococcus saprophyticus NCSL-YWH2 seed tubes and Penicillium steckii NCSL-JXA6 fungal spores (10... 5(Spores / mL) were inoculated in a clean bench into liquid culture medium (100 g / L glucose, 20 g / L ammonium chloride, 8 g / L potassium dihydrogen phosphate, 5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 250 g / L sodium chloride, and deionized water was added to bring the volume to 1 L), and cultured at 30℃ and 250 rpm for 3 days to obtain 15 g / L bacterial mycelial ball culture;

[0212] Step 2: The mycelial ball culture obtained in Step 1 was directly added to a membrane bioreactor (reactor system 6 L) containing produced water from a gas field in Xinjiang (salinity 20 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 34 mg / L) at an inoculation rate of 2 g / L (based on dry basis).

[0213] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 6 h and an organic loading of 2.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0214] Step 4: Every 6 hours, 4 g (based on dry basis) of microorganisms are filtered and separated from the produced water of the oil and gas field, placed in a shake flask containing 10 mL of deionized water, and shaken at 30°C and 160 rpm for 12 hours. The microorganisms naturally release the enriched lithium ions. The supernatant is filtered and the released microorganisms are returned to the reactor for further carbon removal and lithium enrichment.

[0215] The specific results are as follows: After 20 days of operation, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the COD removal rate reached 99%, the lithium recovery rate reached 70%, the intracellular lithium enrichment concentration reached 35.7 mg / g stem cells, and the extracted lithium ion concentration was 7110 mg / L.

[0216] Comparative Example 1: Commercially available Aspergillus niger was purchased and used for simultaneous carbon removal and lithium enrichment in a shale gas produced water system in Sichuan (compared with Example 19).

[0217] The Aspergillus niger used in this comparative example was commercially available under the trade name CMCC(F)98003.

[0218] The specific implementation steps are as follows:

[0219] Step 1: Prepare a suspension of Aspergillus niger fungal spores (10... 5(Spores / mL) were inoculated in a clean bench into liquid culture medium (100 g / L glucose, 20 g / L ammonium chloride, 8 g / L potassium dihydrogen phosphate, 5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 30 g / L sodium chloride, and deionized water to a final volume of 1 L), and cultured at 30°C and 250 rpm for 3 days to obtain 15 g / L mycelial ball culture;

[0220] Step 2: The mycelial ball culture obtained in Step 1 was directly added to a sequencing batch reactor (reactor system 6 L) containing produced water from a shale gas mine in Sichuan (salinity 3 wt%, chemical oxygen demand COD concentration 500 mg / L, lithium ion concentration 32 mg / L).

[0221] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 1.0 kg COD / (m³). 3 •d), sludge age 10 days, pH maintained at 7.0-8.5, temperature maintained at 25℃-30℃, microorganisms degrade organic matter in oil and gas field produced water and enrich lithium ions;

[0222] Step 4: After the reactor stabilizes and discharges sludge, 1.2 g (based on dry basis) of the bacterial cells discharged from the reactor is filtered and separated from the produced water of the oil and gas field daily. The particles are crushed by a pulverizer, and the cells are broken up by solid-phase shearing to release the enriched lithium ions. The supernatant is then filtered and collected.

[0223] The specific results are as follows: After 16 days of operation, the bio-carbon removal-lithium enrichment efficiency reached a stable state, the sludge volume stabilized at 2 g / L, the COD removal rate reached 10%, the lithium recovery rate reached 0%, there was no intracellular lithium enrichment, and the extracted lithium ion concentration was 0 mg / L.

[0224] Comparative Example 2: Commercially available brewing yeast was purchased and used for simultaneous carbon removal and lithium enrichment in the produced water system of a gas field in Xinjiang (compared with Example 13).

[0225] The brewing yeast (Saccharomyces cerevisiae) used in this comparative example was commercially available under the trade name Delf-28653.

[0226] The specific implementation steps are as follows:

[0227] Step 1: Inoculate the Saccharomyces cerevisiae incubation tubes into liquid culture medium (10 g / L glucose, 1 g / L ammonium chloride, 1 g / L potassium dihydrogen phosphate, 0.5 g / L magnesium sulfate heptahydrate, 0 g / L lithium chloride, 100 g / L sodium chloride, and add deionized water to a final volume of 1 L) in a clean bench and incubate at 30°C and 160 rpm for 2 days to obtain a 2 g / L microbial suspension.

[0228] Step 2: The microbial suspension culture obtained in Step 1 is directly added at an inoculum rate of 2 g / L (based on dry basis) to an aerobic granular sludge reactor (reactor system 1 L) containing produced water from a gas field in Xinjiang (salinity 10 wt%, chemical oxygen demand COD concentration 1000 mg / L, lithium ion concentration 50 mg / L).

[0229] Step 3: Run the reactor from Step 2 with a hydraulic retention time of 12 h and an organic loading of 2.0 kg COD / (m³). 3 •d), pH is maintained at 7.0–8.5, temperature is maintained at 25℃–30℃, and microorganisms degrade organic matter in produced water from oil and gas fields and enrich lithium ions;

[0230] Step 4: 0.2 g (based on dry basis) of bacterial cells discharged from the reactor was filtered and separated from the produced water of the oil and gas field. The cells were placed in a shake flask containing 10 mL of 100 g / L glucose solution and mixed at 30°C and 160 rpm for 2 h. After filtration, the cells were placed in a shake flask containing 10 mL of deionized water and mixed at 30°C and 160 rpm for 2 h. The mixture was then frozen at -80°C for 2 hours and thawed at 30°C. This process was repeated 3 to 5 times to break the cells and release the enriched lithium ions using osmotic pressure shock and repeated freeze-thaw cycles. The supernatant was then filtered and collected.

[0231] The specific results are as follows: the reactor could not operate stably, the COD removal rate was 1%, the lithium recovery rate was 1%, the intracellular lithium enrichment concentration was unstable, and long-term lithium enrichment experiments could not be carried out.

[0232] Based on the results of Examples 1-21 and Comparative Examples 1-2, the simultaneous carbon removal-lithium enrichment biological treatment method of the present invention exhibits significant advantages. This method is applicable to various complex oil and gas field produced water qualities, including oilfield produced water, gas field produced water, shale gas produced water, tight gas produced water, oilfield fracturing flowback fluid, and shale gas fracturing flowback fluid, achieving selective enrichment of lithium ions while effectively degrading organic matter.

[0233] The results of the comparative examples further confirm the inventiveness of this invention. Comparative Example 1 used commercial Aspergillus niger, achieving a COD removal rate of only 10% and failing to achieve lithium enrichment; Comparative Example 2 used commercial Saccharomyces cerevisiae, which struggled to adapt to the produced water environment of gas fields and could not grow or degrade organic matter. This indicates that not just any microorganism with the function of degrading produced water in oil and gas fields, or any microorganism with lithium enrichment function, can achieve simultaneous carbon removal and lithium enrichment in oil and gas field produced water systems. The specific functional strains selected in this invention are key to achieving simultaneous carbon removal and lithium enrichment in oil and gas field produced water systems.

[0234] Therefore, this invention successfully overcomes the limitation of traditional biological treatment methods, which can only remove organic matter, and solves the technical challenge of lithium resource recovery from produced water in oil and gas fields. This method organically combines pollution control with resource recovery, providing an efficient and feasible technical solution for the green and low-carbon treatment of produced water and lithium resource recovery in oil and gas fields, which is of great significance to the national ecological environment and new energy strategy.

[0235] The above description is merely a preferred embodiment for explaining the present invention and is not intended to limit the present invention in any way. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included within the scope of protection intended by the present invention.

Claims

1. A biological treatment and resource utilization method for simultaneous carbon removal and lithium enrichment of produced water from oil and gas fields, characterized in that, Includes the following steps: Step 1: Inoculate the microorganisms into a liquid culture medium and culture them to obtain a microbial culture solution or culture; Step 2: Add the microbial culture medium and / or culture obtained in Step 1 directly and / or add it after treatment to the reactor containing produced water from the oil and gas field to be treated; Step 3: Run the reactor from Step 2, where microorganisms degrade organic matter in the produced water from the oil and gas field and enrich lithium ions; Step 4: Separate the microorganisms from the produced water of the oil and gas field and extract the lithium ions enriched in the microorganisms; The microorganism is selected from one or more combinations of the following microorganisms: Staphylococcus saprophyticus ( Staphylococcus saprophyticus ), Penicillium fimbriae ( Penicillium steckii ), Highland Bacillus ( Bacillus altitudinis ), fine-particle-alternating spores ( Alternaria tenuissima ), and polyaspergillus ( Aspergillus sydowii ).

2. The method according to claim 1, characterized in that: The saprophytic Staphylococcus ( Staphylococcus saprophyticus ) is saprophytic Staphylococcus ( Staphylococcus saprophyticus NCSL-YWH2, with accession number CGMCC No. 35847; The Penicillium fissure ( Penicillium steckii ) is Penicillium fimbriatum ( Penicillium steckii NCSL-JXA6, with accession number CGMCC No.41831; The Highland Bacillus ( Bacillus altitudinis ) is Highland Bacillus ( Bacillus altitudinis NCSL-CS2, with accession number CGMCC No. 25665; The fine-particle-alternaria ( Alternaria tenuissima ) is a fine-particle-alternating spore ( Alternaria tenuissima NCSL-XY7, with accession number CGMCC No.40313; The polyaspergillus ( Aspergillus sydowii ) is polyaspergillus ( Aspergillus sydowii NXY1, with accession number CGMCC No.40215.

3. The method according to claim 1, characterized in that, The liquid culture medium in step 1 consists of: carbon source 1-100 g / L, ammonium chloride 0.2-20 g / L, potassium dihydrogen phosphate 0.05-8 g / L, magnesium sulfate heptahydrate 0.2-5 g / L, lithium chloride 0-100 g / L, and sodium chloride 0-250 g / L. The carbon source is selected from one or more of glucose, starch, sodium acetate, molasses, methanol, ethylene glycol, glycerol, and sucrose.

4. The method according to claim 1, characterized in that, The cultivation conditions described in step 1 are: temperature 10-35℃, shaking speed 100-250 rpm, and cultivation time 1-10 days.

5. The method according to claim 1, characterized in that, In step 2, the culture medium refers to the suspension culture medium obtained by suspending microorganisms in a liquid culture medium, and the culture refers to the mycelial ball culture obtained by spontaneously forming microorganisms in a liquid culture medium or the functional carrier culture with microorganisms attached obtained by adding a functional carrier for microorganism attachment culture.

6. The method according to claim 1, characterized in that, In step 2, the direct addition includes the direct addition of suspension culture, mycelial ball culture and / or functional carrier culture with attached microorganisms; the post-treatment addition includes adding the suspension culture after centrifugation concentration or immobilization treatment.

7. The method according to claim 1, characterized in that, The produced water from the oil and gas field includes one or more combinations of oil field produced water, gas field produced water, shale gas produced water, tight gas produced water, oil field fracturing flowback fluid, shale gas fracturing flowback fluid, and simulated oil and gas field produced water; the COD of the produced water from the oil and gas field is 100 to 100,000 mg / L, and the lithium ion content is 0.1 to 2,000 mg / L.

8. The method according to claim 1, characterized in that, The organic compound mentioned in step 3 is one or more of the following: hydrocarbons, alcohols, aldehydes, ketones, esters, phenols, surfactants, corrosion inhibitors, bactericides, or oil displacement agents; The hydrocarbons are any one or more of aliphatic hydrocarbons, alkanes, or polycyclic aromatic hydrocarbons; The alcohol is any one or more of methanol, ethylene glycol, or propanol; The aldehyde is glutaraldehyde; The ketones are any one or more of acetone or cyclohexanone; The esters are any one or more of phthalates; The phenols are any one or more of phenol or cresol.

9. The method according to claim 1, characterized in that, The reactor described in step 2 or step 3 is one or more of the following: activated sludge reactor, biofilm reactor, biofilter, membrane bioreactor, and aerobic granular sludge reactor. The reactor operates at a processing temperature of 10–35°C and an organic loading rate of 0.2–6.0 kg COD / (m³). 3 ·d).

10. The method according to claim 1, characterized in that, The methods for extracting lithium ions enriched in microorganisms in step 4 are: natural release in a lithium-free environment, release induced by external ion addition, or release by cell disruption; The added ions include H+ + Na + K + Ca 2+ Mg 2+ One or more of the following; The methods for disrupting cells include one or more of the following: solid-phase shearing, liquid-phase shearing, acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis, organic solvent treatment, heat treatment, osmotic pressure shock, and repeated freeze-thaw cycles.