Advanced mineralization treatment process for oily sludge sewage

Abstract

The invention relates to the technical field of sewage treatment, in particular to a deep mineralization treatment process for oily sludge sewage. Comprising the following steps: chelating heavy metals in the oil sludge sewage and putting a biological agent for deep mineralization treatment. According to the preparation method, ammonium bicarbonate serves as a pore-forming agent and is combined with bagasse to form pores, the principle is that ammonium bicarbonate is decomposed to release gas in the heat treatment process, when the gas escapes from the bagasse, the gas can erode in a formed carbon skeleton and open a rich multi-stage pore channel structure, and meanwhile, the pore-forming effect is greatly improved. Nitrogen-containing active species generated by urea pyrolysis react with a carbon skeleton of bagasse under catalysis of ammonium bicarbonate pyrolysis gas to realize in-situ doping of nitrogen elements, so that nitrogen-containing functional groups are introduced to the surface of a biochar material, the hydrophilicity of the surface of a biochar carrier is enhanced, initial attachment and colonization of negatively-charged microbial cells are attracted, and the biochar carrier is prepared. The efficient loading and enrichment of microorganisms are realized, and the mineralization effect on oil sludge sewage is improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a deep mineralization treatment process for oily sludge wastewater. Background Technology

[0002] With the continuous development of the oil extraction, refining, and transportation industries, a large amount of complex and difficult-to-treat oily sludge wastewater has been generated. This type of wastewater contains a large amount of toxic and harmful petroleum hydrocarbon pollutants such as straight-chain alkanes and polycyclic aromatic hydrocarbons. If not treated properly, it will cause serious long-term damage to the soil and aquatic environment. At present, biological treatment methods are widely used due to their advantages such as low cost and environmental friendliness. However, their treatment effect is often limited by key factors such as the selection of highly efficient functional microorganisms, the loading density of microorganisms in the reactor, and mass transfer efficiency.

[0003] Traditional biological carriers, such as activated carbon and ceramsite, generally suffer from limited specific surface area, simple pore structure, and difficulty in controlling surface properties. This results in low microbial attachment rates, slow biofilm formation, and easy detachment, making it particularly difficult to enrich high concentrations of specific functional bacterial communities. Furthermore, the hydrophobicity and electronegativity of the carrier surface repel negatively charged microbial cells, hindering initial attachment. Simultaneously, crude oil pollutants are complex in composition, and single bacterial species can typically only degrade a limited number of hydrocarbons, easily leading to the accumulation of intermediate metabolites, causing secondary pollution, and making complete mineralization of pollutants difficult.

[0004] Therefore, the present invention provides a deep mineralization treatment process for oily sludge wastewater, thereby solving the problems existing in the prior art. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a deep mineralization treatment process for oily sludge wastewater.

[0006] A deep mineralization treatment process for oily sludge wastewater includes the following steps: S1: Chelating heavy metals in oily sludge wastewater The oily sludge wastewater is stirred to make its composition uniform, and sodium hydroxide is added to adjust the pH value to 8-9. The floating oil phase is separated and recovered by air flotation. Then, 0.5-0.9 g / L of heavy metal chelating agent is added, and the sludge and water are separated by sedimentation filtration to obtain heavy metal chelated precipitate and filtrate. S2: Deep mineralization treatment with biological agents Adjust the pH of the filtrate to 6.5-7.5, add biological agent to the filtrate at a dosage of 20-30 g / L, aerate the filtrate, control the dissolved oxygen at 2-4 mg / L, maintain the temperature at 26-30℃, and stir at 50-60 r / min for 6-7 days for mineralization. Then stop aeration and stirring, and allow the bacteria and newly formed biological sludge to settle naturally and filter, thus completing the mineralization of oily sludge wastewater.

[0007] Furthermore, the preparation method of the biological agent in step S2 includes the following steps: S2.1: Preparation of ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier Sugarcane bagasse powder is obtained by drying sugarcane bagasse. 10-12 parts by weight of sugarcane bagasse powder, 15-20 parts by weight of ammonium bicarbonate and 5-10 parts by weight of urea are dissolved in 50-60 parts by weight of deionized water. Ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier is prepared by segmented heating. S2.2: Preparation of protein-doped biochar composite carrier The zein powder was dissolved in an ethanol aqueous solution to prepare a solution. The ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier and the zein solution were mixed and shaken at a material-to-liquid ratio of 1g:(10-14)mL. Urea was then added and calcined to obtain a protein-doped biochar composite carrier. S2.3: Preparation of biological agents by combined expansion culture of *Pseudomonas galbana* and *Rhodococcus rubrum* Pseudomonas gasseri and Rhodococcus rubrum were inoculated into Erlenmeyer flasks containing crude oil culture medium and cultured for one week in a constant temperature shaker at 30-32℃ and 150-160 rpm to obtain Pseudomonas gasseri and Rhodococcus rubrum bacterial suspensions. The Pseudomonas gasseri and Rhodococcus rubrum bacterial suspensions were purified and cultured, and then co-inoculated into Erlenmeyer flasks containing liquid culture medium. Sodium chloride solution was added to prepare an immobilized compound bacterial suspension. The protein-doped biochar composite carrier and the immobilized compound bacterial suspension were mixed and shaken in the Erlenmeyer flask at a material-to-liquid ratio of 1g:(15-20)mL to obtain the biological agent.

[0008] Further, step S2.1, preparing the ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier, specifically involves: Wash the bagasse three times with deionized water to remove mud and sand, then place it in an oven and dry it at 100-110℃ for 12-13 hours. Then pulverize it through an 80-mesh sieve to obtain bagasse powder. Dissolve 10-12 parts by weight of bagasse powder, 15-20 parts by weight of ammonium bicarbonate, and 5-10 parts by weight of urea in 50-60 parts by weight of deionized water, stir thoroughly to form a uniform slurry, let stand for 6-8 hours, and then dry in an oven at 60-80℃ to obtain a mixed precursor of bagasse / ammonium bicarbonate / urea. Feed it into a tube furnace and heat it to 250-260℃ at a rate of 5-7℃ / min, then hold it for 30-40 minutes, and continue to heat it to 650-700℃ at a rate of 5-7℃ / min, and hold it for 1-2 hours. After that, allow the furnace to cool naturally to room temperature of 22-24℃ under continuous nitrogen purging. Wash it once with 0.1M dilute hydrochloric acid and dry it at 100-110℃ for 12-13 hours to obtain an ammonium bicarbonate pore-forming bagasse microbial carrier.

[0009] Further, step S2.2, the preparation of the protein-doped biochar composite support, specifically involves: The zein powder was dissolved in an ethanol aqueous solution to prepare a zein solution, and a 5-7% (w / v) zein solution was prepared. The ammonium bicarbonate bagasse microbial carrier with the zein solution was mixed with the zein solution at a material-to-liquid ratio of 1g:(10-14)mL. The mixture was placed on a constant temperature shaker and shaken at room temperature of 22-24℃ for 6-8h. Then it was dried at 60-70℃ for 2-3h to obtain the pore-filling microbial carrier. Dissolve urea in deionized water to prepare a 10% (w / v) urea solution; The microbial carrier with pores was mixed with urea solution at a ratio of 1g:(5-7)mL, and soaked at room temperature for 2-3h. The temperature was then increased to 250-260℃ at 5℃ / min and kept at that temperature for 30-40min. Finally, the temperature was cooled to room temperature to obtain the protein-doped biochar composite carrier.

[0010] Further, step S2.3, the combined expansion culture of *Pseudomonas gasseri* and *Rhodococcus rubrum* to prepare the biological agent, specifically involves: Pseudomonas galbana and Rhodococcus rubrum were inoculated into Erlenmeyer flasks containing crude oil culture medium at an inoculation rate of 1-5% and cultured in a constant temperature shaker at 30-32℃ and 150-160 rpm for one week to obtain Pseudomonas galbana and Rhodococcus rubrum bacterial suspensions. The *Pseudomonas gasseri* and *Rhodococcus rubrum* bacterial suspensions were purified and cultured. The purified *Pseudomonas gasseri* and *Rhodococcus rubrum* bacterial suspensions were co-inoculated into Erlenmeyer flasks containing liquid culture medium. The inoculation amount of *Pseudomonas gasseri* was 2-4%, and the inoculation amount of *Rhodococcus rubrum* was 1-3%. The inoculated Erlenmeyer flasks were placed in a constant temperature shaker at 30-32℃ and 150-200 rpm for 24-48 hours to obtain the culture medium. The culture medium was centrifuged at 8000-9000 rpm for 10-14 minutes, and the supernatant was removed. The bacterial sludge was resuspended in a 0.85 wt% sodium chloride solution and centrifuged again at 8000-9000 rpm for 10-14 minutes. Then, 0.85 wt% sodium chloride solution was added to prepare an immobilized compound bacterial suspension with a wet weight concentration of 25-35 g / L. The protein-doped biochar composite carrier and the immobilized compound bacterial solution were mixed in an Erlenmeyer flask at a material-to-liquid ratio of 1g:(15-20)mL. The mixture was placed on a shaker at 2-4℃ and shaken at 100-200rpm for 8-12h. Then, it was allowed to stand at 15-25℃ for 24-26h to obtain the biological agent.

[0011] Furthermore, the concentration of the ethanol aqueous solution in step S2.2 is 70-80 wt%.

[0012] Further, the crude oil culture medium in step S2.3 is formulated with 1-1.2 g / L of K2HPO4, 1-1.2 g / L of KH2PO4, 1-1.2 g / L of NH4NO3, 0.1-0.3 g / L of MgSO4, 0.01-0.03 g / L of CaCl2 and 1-3% crude oil by total mass.

[0013] Furthermore, the liquid culture medium in step S2.3 is specifically LB medium.

[0014] Furthermore, in step S2.3, *Pseudomonas gasseri* specifically refers to *Pseudomonas gasseri* strain AD1, and *Rhodococcus rubrum* specifically refers to *Rhodococcus rubrum* strain HDRR2Y.

[0015] Furthermore, the heavy metal chelating agent in step S1 is ethylenediaminetetraacetic acid.

[0016] The present invention has the following advantages: 1. In this invention, ammonium bicarbonate is used as a pore-forming agent and combined with bagasse to create pores. The principle is that ammonium bicarbonate decomposes and releases gas during heat treatment. When the gas escapes from inside the bagasse, it can erode and expand the rich hierarchical pore structure in the formed carbon skeleton, significantly increasing the specific surface area and pore volume of the bagasse biochar carrier. This provides a wider attachment space and shelter for microorganisms and facilitates the diffusion and transport of nutrients and metabolites. Furthermore, the gas produced by the decomposition of ammonium bicarbonate at a relatively low temperature occurs during the stage when the bagasse fibers are softened but not yet carbonized. This process expands the fibrous network of bagasse, forming numerous interconnected macropores and mesopores. This perfectly preserves the natural fibrous skeleton of bagasse. Simultaneously, the nitrogen-containing active species produced by urea pyrolysis react with the carbon skeleton of bagasse under the catalysis of ammonium bicarbonate pyrolysis gas, achieving in-situ doping of nitrogen. This introduces nitrogen-containing functional groups onto the surface of the biochar material, enhancing the hydrophilicity of the biochar carrier surface and changing its surface charge from negative to positive. This effectively promotes the initial attachment and colonization of negatively charged microbial cells through electrostatic attraction, achieving efficient loading and enrichment of microorganisms and improving the mineralization effect on oily sludge wastewater.

[0017] 2. This invention introduces zein into a porous sugarcane bagasse microbial carrier. Utilizing the wetting and film-forming properties of zein solution within the carrier pores, a finer secondary pore structure is constructed by modifying the inner surfaces of macropores and mesopores, significantly increasing the specific surface area of ​​the carrier. Subsequently, during heat treatment, zein and urea serve as a nitrogen source, with the nitrogen atoms in the zein molecule being in-situ doped into the carbon skeleton, achieving stable and deep nitrogen doping and introducing a large number of nitrogen-containing functional groups. This modified, fine, multi-level pore structure provides microorganisms with a broader and more diverse space for attachment and colonization. Simultaneously, the enhanced hydrophilicity and electronegativity of the carrier surface due to nitrogen doping can strongly adsorb microorganisms through electrostatic interactions, significantly increasing the microbial load and biofilm formation efficiency, thereby enhancing the degradation capacity and operational stability of the biological treatment system.

[0018] 3. This invention utilizes the complementary metabolic functions of *Pseudomonas gasseri* and *Rhodococcus rubrum* to prepare a compound bacterial solution. *Pseudomonas gasseri* excels at degrading easily decomposable components in crude oil, such as straight-chain alkanes, while the enzyme system of *Rhodococcus rubrum* specializes in degrading stubborn pollutants such as polycyclic aromatic hydrocarbons. The synergistic effect of the two can cover a wider range of hydrocarbons and avoid the accumulation of intermediate products through metabolic relay, achieving more thorough degradation. Through division of labor and cooperation, hydrocarbons of different components in crude oil are simultaneously and efficiently converted into carbon dioxide, water, and bacterial biomass, thereby significantly improving the total organic carbon removal rate and final mineralization degree of the system. This not only accelerates the purification speed of oil sludge wastewater but also reduces the presence of toxic intermediate products at the source due to its effective decomposition of recalcitrant components, improving the thoroughness of the treatment process and environmental safety. Attached Figure Description

[0019] Figure 1 This is a flow chart of the deep mineralization treatment process for oily sludge wastewater according to the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0021] Example 1: A deep mineralization treatment process for oily sludge wastewater, such as Figure 1 As shown, it includes the following steps: S1: Chelating heavy metals in oily sludge wastewater The oily sludge wastewater was stirred to make its composition uniform, and sodium hydroxide was added to adjust the pH value to 8. The floating oil phase was separated and recovered by air flotation. Then, 0.5 g / L of heavy metal chelating agent ethylenediaminetetraacetic acid was added, and the sludge and water were separated by sedimentation filtration to obtain heavy metal chelated precipitate and filtrate. S2: Deep mineralization treatment with biological agents Adjust the pH of the filtrate to 6.5, add biological agent to the filtrate at a dosage of 20 g / L, aerate the filtrate, control the dissolved oxygen at 2 mg / L, maintain the temperature at 26℃, and stir at 50 r / min for 6 days for mineralization. Then stop aeration and stirring, and allow the bacteria and newly formed biological sludge to settle naturally and filter, thus completing the mineralization of oily sludge wastewater.

[0022] The preparation method of the biological agent in step S2 includes the following steps: S2.1: Preparation of ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier The bagasse was washed three times with deionized water to remove mud and sand, then placed in an oven and dried at 100°C for 12 hours. After that, it was pulverized and passed through an 80-mesh sieve to obtain bagasse powder.

[0023] 10 parts by weight of bagasse powder, 15 parts by weight of ammonium bicarbonate and 5 parts by weight of urea were dissolved in 50 parts by weight of deionized water and stirred thoroughly to form a uniform slurry. The mixture was allowed to stand for 6 hours and then dried in an oven at 60°C to obtain a mixed precursor of bagasse / ammonium bicarbonate / urea. The precursor was fed into a tube furnace and heated to 250°C at a rate of 5°C / min, held for 30 minutes, and then heated to 650°C at a rate of 5°C / min and held for 1 hour. After the process was completed, the furnace was allowed to cool naturally to room temperature of 22°C under continuous nitrogen purging. The mixture was washed once with 0.1M dilute hydrochloric acid and dried at 100°C for 12 hours to obtain an ammonium bicarbonate pore-forming bagasse microbial carrier. S2.2: Preparation of protein-doped biochar composite carrier The zein powder was dissolved in a 70wt% ethanol aqueous solution to prepare a 5% (w / v) zein solution. The ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier was mixed with the zein solution at a material-liquid ratio of 1g:10mL and placed on a constant temperature shaker. The mixture was shaken at room temperature of 22℃ for 6h and then dried at 60℃ for 2h to obtain the pore-filling microbial carrier. Dissolve urea in deionized water to prepare a 10% (w / v) urea solution; The microbial carrier filled with pores was mixed with urea solution at a ratio of 1g:5mL, and impregnated at room temperature for 2h. The temperature was then increased to 250℃ at 5℃ / min and kept at that temperature for 30min. Finally, the temperature was cooled to room temperature to obtain a protein-doped biochar composite carrier. S2.3: Preparation of biological agents by combined expansion culture of *Pseudomonas galbana* and *Rhodococcus rubrum* The strains of Pseudomonas galbana AD1 and Rhodococcus rubrum HDRR2Y were inoculated at a rate of 1% into Erlenmeyer flasks containing crude oil culture medium and cultured for one week at 30°C and 150 rpm in a constant temperature shaker to obtain Pseudomonas galbana bacterial suspension and Rhodococcus rubrum bacterial suspension. The bacterial suspensions of *Pseudomonas gasseri* and *Rhodococcus rubrum* were purified and cultured. The purified *Pseudomonas gasseri* and *Rhodococcus rubrum* suspensions were co-inoculated into Erlenmeyer flasks containing LB medium, with an inoculation amount of 2% for *Pseudomonas gasseri* and 1% for *Rhodococcus rubrum*. The inoculated Erlenmeyer flasks were placed in a constant temperature shaker at 30℃ and 150 rpm for 24 h to obtain the culture medium. The culture medium was centrifuged at 8000 rpm for 10 min, the supernatant was removed, and the bacterial sludge was resuspended in a 0.85 wt% sodium chloride solution. It was then centrifuged again at 8000 rpm for 10 min, and 0.85 wt% sodium chloride solution was added to prepare an immobilized compound bacterial suspension with a wet weight concentration of 25 g / L. The crude oil culture medium was formulated with 1 g / L K2HPO4, 1 g / L KH2PO4, 1 g / L NH4NO3, 0.1 g / L MgSO4, 0.01 g / L CaCl2, and 1% crude oil by total mass.

[0024] The protein-doped biochar composite carrier and the immobilized compound bacterial solution were mixed in an Erlenmeyer flask at a ratio of 1g:15mL. The mixture was placed on a shaker at 2℃ and shaken at 100rpm for 8 hours. Then, it was allowed to stand at 15℃ for 24 hours to obtain the biological agent.

[0025] Example 2: A deep mineralization treatment process for oily sludge wastewater, such as Figure 1 As shown, it includes the following steps: S1: Chelating heavy metals in oily sludge wastewater The oily sludge wastewater was stirred to make its composition uniform, and sodium hydroxide was added to adjust the pH value to 8.5. The floating oil phase was separated and recovered by air flotation. Then, 0.7 g / L of heavy metal chelating agent ethylenediaminetetraacetic acid was added, and the sludge and water were separated by sedimentation filtration to obtain heavy metal chelated precipitate and filtrate. S2: Deep mineralization treatment with biological agents Adjust the pH of the filtrate to 7, add biological agent to the filtrate at a dosage of 25 g / L, aerate the filtrate, control the dissolved oxygen at 3 mg / L, maintain the temperature at 28℃, and stir at 55 r / min for 6.5 days for mineralization. Then stop aeration and stirring, and allow the bacteria and newly formed biological sludge to settle naturally and filter, thus completing the mineralization of oily sludge wastewater.

[0026] The preparation method of the biological agent in step S2 includes the following steps: S2.1: Preparation of ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier The bagasse was washed three times with deionized water to remove mud and sand, then placed in an oven and dried at 105°C for 12.5 hours. After that, it was pulverized and passed through an 80-mesh sieve to obtain bagasse powder.

[0027] 11 parts by weight of bagasse powder, 18 parts by weight of ammonium bicarbonate and 8 parts by weight of urea were dissolved in 55 parts by weight of deionized water and stirred thoroughly to form a uniform slurry. The mixture was allowed to stand for 7 hours and then dried in an oven at 70°C to obtain a mixed precursor of bagasse / ammonium bicarbonate / urea. This precursor was fed into a tube furnace and heated to 255°C at a rate of 6°C / min, held for 35 minutes, and then heated to 675°C at a rate of 6°C / min and held for 1.5 hours. After the process was completed, the furnace was allowed to cool naturally to room temperature of 23°C under continuous nitrogen purging. The mixture was washed once with 0.1M dilute hydrochloric acid and dried at 105°C for 12.5 hours to obtain an ammonium bicarbonate pore-forming bagasse microbial carrier. S2.2: Preparation of protein-doped biochar composite carrier The zein powder was dissolved in a 75wt% ethanol aqueous solution to prepare a 6% (w / v) zein solution. The ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier was mixed with the zein solution at a material-liquid ratio of 1g:12mL and placed on a constant temperature shaker. The mixture was shaken at room temperature of 23℃ for 7h and then dried at 65℃ for 2.5h to obtain the pore-filling microbial carrier. Dissolve urea in deionized water to prepare a 10% (w / v) urea solution; The microbial carrier filled with pores was mixed with urea solution at a ratio of 1g:6mL, and impregnated at room temperature for 2.5h. The temperature was then increased to 255℃ at 5℃ / min and held for 35min. Finally, the temperature was cooled to room temperature to obtain a protein-doped biochar composite carrier. S2.3: Preparation of biological agents by combined expansion culture of *Pseudomonas galbana* and *Rhodococcus rubrum* The *Pseudomonas galbana* AD1 strain and *Rhodococcus rubrum* HDRR2Y strain were inoculated at a rate of 3% into Erlenmeyer flasks containing crude oil culture medium and cultured for one week at 31°C and 155 rpm in a constant temperature shaker to obtain *Pseudomonas galbana* and *Rhodococcus rubrum* bacterial suspensions. The bacterial suspensions of *Pseudomonas gasseri* and *Rhodococcus rubrum* were purified and cultured. The purified *Pseudomonas gasseri* and *Rhodococcus rubrum* suspensions were co-inoculated into Erlenmeyer flasks containing LB medium, with an inoculation amount of 3% for *Pseudomonas gasseri* and 2% for *Rhodococcus rubrum*. The inoculated Erlenmeyer flasks were placed in a constant temperature shaker at 31℃ and 175 rpm for 36 h to obtain the culture medium. The culture medium was centrifuged at 8500 r / min for 12 min, the supernatant was removed, and the bacterial sludge was resuspended in a 0.85 wt% sodium chloride solution. It was then centrifuged again at 8500 r / min for 12 min, and 0.85 wt% sodium chloride solution was added to prepare an immobilized compound bacterial suspension with a wet weight concentration of 30 g / L. The crude oil culture medium consisted of 1.1 g / L K₂HPO₄, 1.1 g / L KH₂PO₄, 1.1 g / L NH₄NO₃, 0.2 g / L MgSO₄, 0.02 g / L CaCl₂, and 2% crude oil by total mass.

[0028] The protein-doped biochar composite carrier and the immobilized compound bacterial solution were mixed in an Erlenmeyer flask at a material-to-liquid ratio of 1g:18mL. The mixture was placed on a shaker at 3℃ and shaken at 150rpm for 10h. Subsequently, it was allowed to stand at 20℃ for 25h to obtain the biological agent.

[0029] Example 3: A deep mineralization treatment process for oily sludge wastewater, such as Figure 1 As shown, it includes the following steps: S1: Chelating heavy metals in oily sludge wastewater The oily sludge wastewater was stirred to make its composition uniform, and sodium hydroxide was added to adjust the pH value to 9. The floating oil phase was separated and recovered by air flotation. Then, 0.9 g / L of heavy metal chelating agent ethylenediaminetetraacetic acid was added, and the sludge and water were separated by sedimentation filtration to obtain heavy metal chelated precipitate and filtrate. S2: Deep mineralization treatment with biological agents Adjust the pH of the filtrate to 7.5, add biological agent to the filtrate at a dosage of 30 g / L, aerate the filtrate, control the dissolved oxygen at 4 mg / L, maintain the temperature at 30℃, and stir at 60 r / min for 7 days for mineralization. Then stop aeration and stirring, and allow the bacteria and newly formed biological sludge to settle naturally and filter, thus completing the mineralization of oily sludge wastewater.

[0030] The preparation method of the biological agent in step S2 includes the following steps: S2.1: Preparation of ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier The bagasse was washed three times with deionized water to remove mud and sand, then placed in an oven and dried at 110°C for 13 hours. After that, it was pulverized and passed through an 80-mesh sieve to obtain bagasse powder.

[0031] 12 parts by weight of bagasse powder, 20 parts by weight of ammonium bicarbonate and 10 parts by weight of urea were dissolved in 60 parts by weight of deionized water and stirred thoroughly to form a uniform slurry. The mixture was allowed to stand for 8 hours and then dried in an oven at 80°C to obtain a mixed precursor of bagasse / ammonium bicarbonate / urea. The precursor was fed into a tube furnace and heated to 260°C at a rate of 7°C / min, held for 40 minutes, and then heated to 700°C at a rate of 7°C / min and held for 2 hours. After the process was completed, the furnace was allowed to cool naturally to room temperature of 24°C under continuous nitrogen purging. The mixture was washed once with 0.1M dilute hydrochloric acid and dried at 110°C for 13 hours to obtain an ammonium bicarbonate pore-forming bagasse microbial carrier. S2.2: Preparation of protein-doped biochar composite carrier The zein powder was dissolved in an 80wt% ethanol aqueous solution to prepare a 7% (w / v) zein solution. The ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier was mixed with the zein solution at a material-liquid ratio of 1g:14mL and placed on a constant temperature shaker. The mixture was shaken at room temperature of 24℃ for 8 hours and then dried at 70℃ for 3 hours to obtain the pore-filling microbial carrier. Dissolve urea in deionized water to prepare a 10% (w / v) urea solution; The microbial carrier filled with pores was mixed with urea solution at a ratio of 1g:7mL, and impregnated at room temperature for 3h. The temperature was then increased to 260℃ at 5℃ / min and kept at that temperature for 40min. Finally, the temperature was cooled to room temperature to obtain a protein-doped biochar composite carrier. S2.3: Preparation of biological agents by combined expansion culture of *Pseudomonas galbana* and *Rhodococcus rubrum* The strains of Pseudomonas galbana AD1 and Rhodococcus rubrum HDRR2Y were inoculated into Erlenmeyer flasks containing crude oil culture medium at an inoculation rate of 5%, and cultured in a constant temperature shaker at 32°C and 160 rpm for one week to obtain Pseudomonas galbana bacterial suspension and Rhodococcus rubrum bacterial suspension. The bacterial suspensions of *Pseudomonas gasseri* and *Rhodococcus rubrum* were purified and cultured. The purified *Pseudomonas gasseri* and *Rhodococcus rubrum* suspensions were co-inoculated into Erlenmeyer flasks containing LB medium, with an inoculation amount of 4% for *Pseudomonas gasseri* and 3% for *Rhodococcus rubrum*. The inoculated Erlenmeyer flasks were placed in a constant temperature shaker at 32℃ and 200 rpm for 48 h to obtain the culture medium. The culture medium was centrifuged at 9000 r / min for 14 min, the supernatant was removed, and the bacterial sludge was resuspended in a 0.85 wt% sodium chloride solution. It was then centrifuged again at 9000 r / min for 14 min, and 0.85 wt% sodium chloride solution was added to prepare an immobilized compound bacterial suspension with a wet weight concentration of 35 g / L. The crude oil culture medium consisted of 1.2 g / L K₂HPO₄, 1.2 g / L KH₂PO₄, 1.2 g / L NH₄NO₃, 0.3 g / L MgSO₄, 0.03 g / L CaCl₂, and 3% crude oil by total mass.

[0032] The protein-doped biochar composite carrier and the immobilized compound bacterial solution were mixed in an Erlenmeyer flask at a ratio of 1g:20mL. The mixture was placed on a shaker at 4℃ and shaken at 200rpm for 12h. Then, it was allowed to stand at 25℃ for 26h to obtain the biological agent.

[0033] Comparative Example 1: Compared with Example 1, the difference of Comparative Example 1 is that the ammonium bicarbonate in step S2.1 is replaced with urea by mass, while the other steps remain unchanged. It is referred to as Comparative Example 1.

[0034] Comparative Example 2: Compared with Example 1, Comparative Example 2 differs in that the mass of urea in step S2.1 is replaced with ammonium bicarbonate, while the other steps remain unchanged. This is referred to as Comparative Example 2.

[0035] Comparative Example 3: Compared with Example 1, Comparative Example 3 differs in that, in step S2.2, zein is replaced by sodium dodecyl sulfate, while the other steps remain unchanged. This is referred to as Comparative Example 3.

[0036] Comparative Example 4: Compared with Example 1, the difference of Comparative Example 4 is that in step S2.3, the Pseudomonas gasseri AD1 strain is replaced with Rhodococcus erythrosporum HDRR2Y strain, while the other steps remain unchanged. This is referred to as Comparative Example 4.

[0037] Comparative Example 5: Compared with Example 1, Comparative Example 5 differs in that in step S2.3, the Rhodococcus erythrocytes HDRR2Y strain is replaced with Pseudomonas galbana AD1 strain, while the other steps remain unchanged. This is referred to as Comparative Example 5.

[0038] The total petroleum hydrocarbon content in the oily sludge wastewater of Examples 1-3 and Comparative Examples 3-5 before and after steps S1 and S2 was detected by infrared spectrophotometry according to the national standard HJ637-2018, and the petroleum hydrocarbon removal rate was calculated. The results are shown in Table 1.

[0039] Petroleum hydrocarbon removal rate = (1 - total petroleum hydrocarbon content in the oily sludge wastewater after steps S1 and S2 / total petroleum hydrocarbon content in the oily sludge wastewater before steps S1 and S2) × 100%.

[0040] After preparing the immobilized compound bacterial solutions in Examples 1-3 and Comparative Examples 1-3, 1g of samples were taken, and the viable bacteria count was calculated using the plate count method. The test was repeated three times and the average value was taken. The results are shown in Table 2.

[0041]

[0042]

[0043] As shown in Table 1, the sample group showed a 13-20 percentage point higher efficiency than the comparative group with any missing key components, demonstrating that the carrier and the dual-bacterial synergistic system are prerequisites for achieving high petroleum hydrocarbon removal rates. *Pseudomonas gasseri* rapidly degrades long-chain alkanes and produces surfactants, reducing interfacial tension; *Rhodococcus rubrum* excels at degrading polycyclic aromatic hydrocarbons and polar components; the dual bacteria form complementary micro-niches on the same carrier, resulting in a higher total petroleum hydrocarbon removal rate than that of single bacteria.

[0044] As shown in Table 2, the plate count indicates that the total viable bacteria count in the example group remained stable at 10 × 10⁻⁶. 9 The concentrations were above CFU / mL, while all comparative samples were less than 8.8 × 10⁻⁶. 9 The combination of CFU / mL ammonium bicarbonate pore-forming and protein doping provides a favorable microenvironment for the bacteria and maintains inoculation activity, thereby increasing the microbial content on the carrier and maintaining a high petroleum hydrocarbon removal rate through microorganisms.

[0045] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A deep mineralization treatment process for oily sludge wastewater, characterized in that, Includes the following steps: S1: Chelating heavy metals in oily sludge wastewater The oily sludge wastewater is stirred to make its composition uniform, and sodium hydroxide is added to adjust the pH value to 8-9. The floating oil phase is separated and recovered by air flotation. Then, 0.5-0.9 g / L of heavy metal chelating agent is added, and the sludge and water are separated by sedimentation filtration to obtain heavy metal chelated precipitate and filtrate. S2: Deep mineralization treatment with biological agents Adjust the pH of the filtrate to 6.5-7.5, add biological agent to the filtrate at a dosage of 20-30 g / L, aerate the filtrate, control the dissolved oxygen at 2-4 mg / L, maintain the temperature at 26-30℃, and stir at 50-60 r / min for 6-7 days for mineralization. Then stop aeration and stirring, and allow the bacteria and newly formed biological sludge to settle naturally and filter, thus completing the mineralization of oily sludge wastewater.

2. The deep mineralization treatment process for oily sludge wastewater according to claim 1, characterized in that, The preparation method of the biological agent in step S2 includes the following steps: S2.1: Preparation of ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier Sugarcane bagasse powder is obtained by drying sugarcane bagasse. 10-12 parts by weight of sugarcane bagasse powder, 15-20 parts by weight of ammonium bicarbonate and 5-10 parts by weight of urea are dissolved in 50-60 parts by weight of deionized water. Ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier is prepared by segmented heating. S2.2: Preparation of protein-doped biochar composite carrier The zein powder was dissolved in an ethanol aqueous solution to prepare a zein solution. The ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier and the zein solution were mixed and shaken at a material-to-liquid ratio of 1g:(10-14)mL. Urea was then added and calcined to obtain a protein-doped biochar composite carrier. S2.3: Preparation of biological agents by combined expansion culture of *Pseudomonas galbana* and *Rhodococcus rubrum* Pseudomonas gasseri and Rhodococcus rubrum were inoculated into Erlenmeyer flasks containing crude oil culture medium and cultured for one week in a constant temperature shaker at 30-32℃ and 150-160 rpm to obtain Pseudomonas gasseri and Rhodococcus rubrum bacterial suspensions. The Pseudomonas gasseri and Rhodococcus rubrum bacterial suspensions were purified and cultured, and then co-inoculated into Erlenmeyer flasks containing liquid culture medium. Sodium chloride solution was added to prepare an immobilized compound bacterial suspension. The protein-doped biochar composite carrier and the immobilized compound bacterial suspension were mixed and shaken in the Erlenmeyer flask at a material-to-liquid ratio of 1g:(15-20)mL to obtain the biological agent.

3. The deep mineralization treatment process for oily sludge wastewater according to claim 2, characterized in that, Step S2.1, the preparation of ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier, specifically involves: Wash the bagasse three times with deionized water to remove mud and sand, then place it in an oven and dry it at 100-110℃ for 12-13 hours. After that, pulverize it and pass it through an 80-mesh sieve to obtain bagasse powder. Dissolve 10-12 parts by weight of bagasse powder, 15-20 parts by weight of ammonium bicarbonate, and 5-10 parts by weight of urea in 50-60 parts by weight of deionized water, stir thoroughly to form a uniform slurry, let stand for 6-8 hours, and then dry in an oven at 60-80℃ to obtain a mixed precursor of bagasse / ammonium bicarbonate / urea. Feed it into a tube furnace and heat it to 250-260℃ at a rate of 5-7℃ / min, then hold it for 30-40 minutes, and continue to heat it to 650-700℃ at a rate of 5-7℃ / min, and hold it for 1-2 hours. After that, allow the furnace to cool naturally to room temperature of 22-24℃ under continuous nitrogen purging. Wash it once with 0.1M dilute hydrochloric acid and dry it at 100-110℃ for 12-13 hours to obtain an ammonium bicarbonate pore-forming bagasse microbial carrier.

4. The deep mineralization treatment process for oily sludge wastewater according to claim 3, characterized in that, Step S2.2, the preparation of the protein-doped biochar composite support, specifically involves: Dissolve zein powder in an ethanol aqueous solution to prepare a 5-7% (w / v) zein solution. Mix the ammonium bicarbonate pore-forming sugarcane bagasse microbial carrier with the zein solution at a material-to-liquid ratio of 1g:(10-14)mL. Place the mixture on a constant temperature shaker and shake at room temperature (22-24℃) for 6-8 hours. Then dry it at 60-70℃ for 2-3 hours to obtain the pore-filling microbial carrier. Dissolve urea in deionized water to prepare a 10% (w / v) urea solution; The microbial carrier with pores was mixed with urea solution at a ratio of 1g:(5-7)mL, and soaked at room temperature for 2-3h. The temperature was then increased to 250-260℃ at 5℃ / min and kept at that temperature for 30-40min. Finally, the temperature was cooled to room temperature to obtain the protein-doped biochar composite carrier.

5. The deep mineralization treatment process for oily sludge wastewater according to claim 4, characterized in that, Step S2.3, the preparation of the biological agent by combined expansion culture of *Pseudomonas gasseri* and *Rhodococcus rubrum*, specifically involves: Pseudomonas galbana and Rhodococcus rubrum were inoculated into Erlenmeyer flasks containing crude oil culture medium at an inoculation rate of 1-5% and cultured in a constant temperature shaker at 30-32℃ and 150-160 rpm for one week to obtain Pseudomonas galbana and Rhodococcus rubrum bacterial suspensions. The *Pseudomonas gasseri* and *Rhodococcus rubrum* bacterial suspensions were purified and cultured. The purified *Pseudomonas gasseri* and *Rhodococcus rubrum* bacterial suspensions were co-inoculated into Erlenmeyer flasks containing liquid culture medium. The inoculation amount of *Pseudomonas gasseri* was 2-4%, and the inoculation amount of *Rhodococcus rubrum* was 1-3%. The inoculated Erlenmeyer flasks were placed in a constant temperature shaker at 30-32℃ and 150-200 rpm for 24-48 hours to obtain the culture medium. The culture medium was centrifuged at 8000-9000 rpm for 10-14 minutes, and the supernatant was removed. The bacterial sludge was resuspended in a 0.85 wt% sodium chloride solution and centrifuged again at 8000-9000 rpm for 10-14 minutes. Then, 0.85 wt% sodium chloride solution was added to prepare an immobilized compound bacterial suspension with a wet weight concentration of 25-35 g / L. The protein-doped biochar composite carrier and the immobilized compound bacterial solution were mixed in an Erlenmeyer flask at a material-to-liquid ratio of 1g:(15-20)mL. The mixture was placed on a shaker at 2-4℃ and shaken at 100-200rpm for 8-12h. Then, it was allowed to stand at 15-25℃ for 24-26h to obtain the biological agent.

6. The deep mineralization treatment process for oily sludge wastewater according to claim 4, characterized in that, The concentration of the ethanol aqueous solution in step S2.2 is 70-80 wt%.

7. The deep mineralization treatment process for oily sludge wastewater according to claim 5, characterized in that, The crude oil culture medium in step S2.3 is formulated with 1-1.2 g / L of K2HPO4, 1-1.2 g / L of KH2PO4, 1-1.2 g / L of NH4NO3, 0.1-0.3 g / L of MgSO4, 0.01-0.03 g / L of CaCl2 and 1-3% crude oil by total mass.

8. The deep mineralization treatment process for oily sludge wastewater according to claim 5, characterized in that, The liquid culture medium in step S2.3 is specifically LB medium.

9. The deep mineralization treatment process for oily sludge wastewater according to claim 5, characterized in that, In step S2.3, *Pseudomonas galbana* specifically refers to *Pseudomonas galbana* strain AD1, and *Rhodococcus rubrum* specifically refers to *Rhodococcus rubrum* strain HDRR2Y.

10. The deep mineralization treatment process for oily sludge wastewater according to claim 1, characterized in that, The heavy metal chelating agent in step S1 is ethylenediaminetetraacetic acid.

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