A process for treating oily wastewater from kitchens based on delactoming bacteria

Abstract

This invention relates to the field of oily wastewater treatment technology and discloses a process for treating oily kitchen wastewater based on demulsifying bacteria, comprising the following steps: adjusting the pH of the oily kitchen wastewater to 6-9, allowing it to settle, and collecting the scum after skimming to obtain pretreated oily wastewater a; mixing pretreated oily wastewater a with a composite demulsifier, introducing air at 10-20 mm / s, performing air flotation treatment for 45-55 min, and collecting the suspended solids after skimming to obtain pretreated oily wastewater b; filtering pretreated oily wastewater b, collecting the filtrate and precipitate, and recovering and reusing the filtrate. The composite demulsifier can improve the stability of the bacteria in the oily kitchen wastewater and improve the treatment efficiency of the oily kitchen wastewater. After the composite demulsifier absorbs water, swells, and breaks down, the modified nano-carbon black in it can electrostatically bind with the modified carboxymethyl cellulose, causing the adsorbed modified carboxymethyl cellulose to flocculate and settle along with the modified nano-carbon black, and be removed by filtration.

Description

Technical Field

[0001] This invention relates to the field of oily wastewater treatment technology, specifically a process for treating oily kitchen wastewater based on demulsifiers. Background Technology

[0002] Oily wastewater is a pollution source that has attracted attention both domestically and internationally. It is mainly generated through various channels, including the catering industry, food processing industry, gas generation plants, machinery processing, and car wash industry. It is harmful to water bodies, soil, and human health. Among them, kitchen wastewater can produce strong odors, has a high oil content, and contains a large amount of plant fiber and detergent. Moreover, oil easily produces a large amount of free fatty acids. The double electric layer structure of these free fatty acids is compressed and solidified by metal ions in the wastewater, and accumulates on the walls of drainage pipes, causing pipe blockage. Therefore, it is necessary to remove oil from kitchen wastewater.

[0003] Methods for removing oily wastewater include physical, chemical, and biological methods. Among them, biological methods have the advantages of large treatment capacity, easy control, economic feasibility, and no secondary pollution. They utilize demulsifying bacteria or their metabolic processes and products to decompose organic matter in oily wastewater, removing grease from kitchen wastewater, thereby promoting oil-water separation and improving the treatment efficiency of kitchen wastewater. However, demulsifying bacteria are easily affected by the pH and temperature of oily wastewater, leading to their inactivation and affecting the treatment efficiency of oily wastewater. In addition, there are a large number of surface-active compounds on the surface of the oil-in-water emulsion in oily wastewater. These active compounds form a stable rigid film, which hinders the aggregation of oil droplets and affects the treatment efficiency of oily wastewater. Summary of the Invention

[0004] This invention provides a process for treating oily wastewater from kitchens based on demulsifiers, which solves the problems of demulsifiers failing in oily wastewater and the presence of a rigid film on the surface of the oil-in-water emulsion in the oily wastewater hindering the coalescence and precipitation of oil droplets.

[0005] The technical solution of the present invention:

[0006] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0007] S1. After adjusting the pH of the oily wastewater from the kitchen to 6-9, let it stand for 2-5 hours to settle, and collect the scum by skimming to obtain pretreated oily wastewater a;

[0008] S2. Mix the pretreated oily wastewater a with the composite demulsifier, introduce air at 10-20 mm / s, perform air flotation treatment for 45-55 min, skim off the scum and collect the suspended solids to obtain the pretreated oily wastewater b.

[0009] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0010] The composite demulsifier is obtained by modifying core-shell microcapsules with dopamine and then mixing them with modified nano carbon black.

[0011] The core-shell microcapsules are prepared by using a mixture of modified cellulose, sodium alginate and calcium chloride as the wall material and starch-coated microorganisms as the core material.

[0012] The modified cellulose is obtained by reacting cellulose, methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid.

[0013] Furthermore, the oily wastewater from kitchen waste has the following characteristics: Chemical Oxygen Demand (COD) of 90-95 g / L, Oil content of 15-16 g / L, and Ammonium Nitrogen (NH4+) content of... + The concentrations of total nitrogen (TN) were 325-365 mg / L, total phosphorus (TP) were 1848-2000 mg / L, and pH was 83.5-88.6 mg / L.

[0014] Furthermore, the ratio of the amount of pretreated oily wastewater a to the amount of compound demulsifier is (30-50) g: (800-1000) mL.

[0015] Furthermore, the composite demulsifier is prepared by the following steps:

[0016] A1. Add corn starch to deionized water and stir at 75-85℃ until the starch is completely gelatinized. Cool to room temperature, add Bacillus XH-1 bacterial solution, stir for 30 minutes, and dry at room temperature overnight to obtain starch-coated bacterial strain.

[0017] A2. Mix 1-butyl-3-methylimidazolium chloride and cellulose, stir and dissolve at 75-85℃, add potassium persulfate, methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid. After the reaction is complete, cool to room temperature, soak in ethanol, centrifuge and dry to obtain modified cellulose.

[0018] A3. Add modified cellulose to ethanol, stir evenly, add sodium alginate and calcium chloride, stir evenly, add starch-coated bacteria, sonicate, and then vacuum filter to obtain a solid. After drying the solid, obtain core-shell microcapsules.

[0019] A4. Add nano carbon black and polyethyleneimine to deionized water, place in an ultrasonic field, and ultrasonically treat at 55-65℃ for 6-10 hours. After filtration, washing, and freeze-drying, modified nano carbon black is obtained.

[0020] A5. The core-shell microcapsules were added to Tris-HCl buffer solution with pH 8-9, stirred evenly, and then dopamine was added. After the reaction was completed, the mixture was filtered, washed, and dried to obtain dopamine-modified core-shell microcapsules. The dopamine-modified core-shell microcapsules and modified carbon black nanoparticles were added to ethanol, stirred evenly, and then filtered, washed, and dried to obtain a composite demulsifier.

[0021] Furthermore, during the A1 reaction process described above, the hydroxyl groups in the gelatinized corn starch can bind with the Bacillus XH-1 bacterial solution through hydrogen bonds. Moreover, starch has good adhesiveness and film-forming properties, allowing the Bacillus XH-1 bacterial solution to penetrate into the gelatinized corn starch, thereby effectively encapsulating the bacteria and forming a starch inclusion complex, i.e., starch-coated bacteria.

[0022] Furthermore, in the A2 reaction process described above, potassium persulfate acts as an initiator, enabling the hydroxyl groups on the glucose units in cellulose to undergo graft copolymerization with the double bonds of methacryloyloxyethyltrimethylammonium chloride, acrylamide, and 2-acrylamido-2-methyl-1-propanesulfonic acid. This results in the introduction of quaternary ammonium groups, amide groups, and sulfonic acid groups as active adsorption functional groups into the cellulose molecular chain, thereby forming modified cellulose.

[0023] Furthermore, in the A3 reaction process described above, modified cellulose, sodium alginate, and calcium chloride are mixed as wall materials, and starch-coated microorganisms are used as core materials. Calcium ions in calcium chloride can cross-link with modified cellulose and sodium alginate, allowing the starch-coated microorganisms to embed into the microcapsule system, forming core-shell microcapsules.

[0024] Furthermore, during the A4 reaction process described above, in an ultrasonic field of 250W and 40kHz, methyl free radicals are generated on the polyethyleneimine molecular chain, and the carbon atoms on the surface of the nano-carbon black can capture the methyl free radicals, thereby achieving the grafting of polyethyleneimine onto the surface of the nano-carbon black to form modified nano-carbon black.

[0025] Furthermore, during the A5 reaction described above, in the Tris-HCl buffer solution, dopamine can self-polymerize on the surface of the core-shell microcapsules to form polydopamine, resulting in a large number of phenolic hydroxyl groups on the surface of the core-shell microcapsules. These groups can then chemically bond with the modified carbon black nanoparticles, causing the modified carbon black nanoparticles to adhere to the surface of the core-shell microcapsules and form a composite demulsifier.

[0026] Furthermore, in step A1, the ratio of corn starch to deionized water is (4-6) g: (45-55) mL.

[0027] Further, in step A2, the mass ratio of 1-butyl-3-methylimidazolium chloride, cellulose, potassium persulfate, methacryloyloxyethyltrimethylammonium chloride, acrylamide, and 2-acrylamido-2-methyl-1-propanesulfonic acid is (35-45):(1-1.6):(0.02-0.04):(0.2-0.4):(0.2-0.4):(0.3-0.5).

[0028] Further, in step A3, the ratio of the amount of modified cellulose, ethanol, sodium alginate, calcium chloride, and starch-coated bacteria is (2-3)g:(25-35)mL:(1.2-1.4)g:(0.6-0.8)g:(1-1.4)g.

[0029] Further, in step A4, the ratio of the amount of nano-carbon black, polyethyleneimine, and deionized water is (0.6-1)g:(2-3)g:(45-55)mL.

[0030] Further, in step A5, the ratio of the core-shell microcapsules, Tris-HCl buffer, and dopamine is (1-3)g:(25-35)mL:(0.2-0.4)g.

[0031] Further, in step A5, the ratio of the dopamine-modified core-shell microcapsules, modified nano carbon black, and ethanol is (2-3)g:(1-1.4)g:(45-55)mL.

[0032] Further, in step A1, the Bacillus XH-1 bacterial solution is prepared by the following steps: sterilizing the culture medium at 95-105℃ for 20-30 min, cooling it to room temperature, adding Bacillus XH-1 bacteria to the sterilized culture medium, and culturing it at a shaking speed of 170-180 rpm, a temperature of 30-35℃, and a pH of 5-9 for 15-20 h to obtain the Bacillus XH-1 bacterial solution.

[0033] Furthermore, the culture medium is composed of wheat bran, soybean meal powder, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of (26-27):(1-3):(7-9):(5.5-6):(0.5-1.5):(0.5-1.5):(1.2-1.6):(950-1050).

[0034] Furthermore, the frying waste oil is obtained by frying soybean oil at 180-220℃ for 10-12 hours.

[0035] Furthermore, the soybean cake powder is made from yellow soybean cake powder.

[0036] Furthermore, the purity of the nano-carbon black is 99.3-99.7%, and the particle size is 30-40 nm.

[0037] Furthermore, the purity of polyethyleneimine is 99-99.6%, the molecular weight is 600-1000, and the density is 1.1-1.2 g / mL.

[0038] The present invention has the following beneficial effects:

[0039] (1) In the technical solution of the present invention, Bacillus XH-1 has biodegradability and can decompose the interfacial membrane on the surface of the oil-in-water emulsion in kitchen oily wastewater, which has a good demulsification effect, causing oil droplets to aggregate and precipitate, thereby promoting oil-water separation. Bacillus XH-1 can also decompose the oil, organic matter and inorganic matter in kitchen oily wastewater, reduce the nitrogen content and oil content in the wastewater, and improve the treatment efficiency of kitchen oily wastewater. Using corn starch to coat the Bacillus XH-1 bacterial solution can improve the stability of the Bacillus XH-1 bacterial solution in kitchen oily wastewater, avoid the influence of pH and temperature in oily wastewater on Bacillus XH-1, which would cause the demulsifying bacteria to fail, and starch can also provide carbon source for Bacillus XH-1, improve the activity and stability of Bacillus XH-1, and increase the removal efficiency of kitchen oily wastewater.

[0040] (2) In the technical solution of the present invention, cellulose can undergo graft copolymerization with the double bonds of methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid to form modified cellulose. Quaternary ammonium groups, amide groups and sulfonic acid groups are introduced into the cellulose molecular chain to adsorb nitrogen and phosphorus elements in kitchen oily wastewater, thereby removing nitrogen and phosphorus elements from kitchen oily wastewater and making kitchen oily wastewater reach the release standard. Polyethyleneimine is grafted onto the surface of nano carbon black, and the modified nano carbon black can replace the interface film on the surface of the water-in-oil emulsion, causing oil droplets to aggregate and precipitate. It has a synergistic effect with Bacillus XH-1 in terms of demulsification performance, improves demulsification efficiency and improves the treatment efficiency of kitchen oily wastewater.

[0041] (3) In the technical solution of the present invention, modified cellulose, sodium alginate and calcium chloride are mixed as wall material, and starch-coated bacteria are used as core material to prepare core-shell microcapsules. The core-shell microcapsules formed have high stability, which further improves the stability of starch-coated bacteria in kitchen oily wastewater and improves the treatment efficiency of kitchen oily wastewater. Moreover, the modified carboxymethyl cellulose on the surface of the core-shell microcapsules has good adhesion and can adhere to the water-in-oil interface in kitchen oily wastewater. After the surface of the core-shell microcapsules absorbs water, the kitchen oily wastewater enters the core-shell microcapsules and comes into contact with the starch-coated bacteria, thereby decomposing the interface film on the surface of the water-in-oil emulsion in the kitchen oily wastewater and completing the demulsification.

[0042] (4) In the technical solution of the present invention, modified nano carbon black is adhered to the surface of dopamine modified core-shell microcapsules. The composite demulsifier formed utilizes the ability of modified nano carbon black to interact with the surface interface film of oil-in-water emulsion through π-π interaction, so that the composite demulsifier adheres to the surface of oil-in-water emulsion, completes demulsification, and causes a large number of oil droplets to aggregate. After the oil droplets released by the modified nano carbon black and Bacillus XH-1 demulsification aggregate, air is introduced for air flotation treatment. The air bubbles generated in the wastewater can precipitate the aggregated oil droplets to the surface of the oily wastewater in the kitchen. After skimming, the removal of oil is completed.

[0043] (5) In the technical solution of the present invention, after the composite demulsifier absorbs water, swells and breaks, the polyethyleneimine on the surface of the modified nano carbon black released carries a positive charge, which can be electrostatically combined with the hydroxyl groups in the modified carboxymethyl cellulose after adsorbing ammonia and phosphorus elements in the wastewater, so that the adsorbed modified carboxymethyl cellulose flocculates and settles along with the modified nano carbon black, and is removed by filtration. Moreover, the raw materials used in the composite demulsifier are all degradable, avoiding harm to water quality. Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0046] The pH of the oily wastewater from the kitchen was adjusted using a 1 mol / L sodium hydroxide solution.

[0047] Bacillus XH-1: Preservation number CGMCC No. 5460.

[0048] The frying waste oil was obtained by frying soybean oil at 200℃ for 11 hours.

[0049] The soybean meal powder is Y030A, purchased from Beijing Hongrun Baoshun Technology Co., Ltd.

[0050] The wheat bran was purchased from Shandong Luhua (Yanjin) Flour Food Co., Ltd.

[0051] The purity of the nano carbon black is 99.5%, and the particle size is 35nm.

[0052] The purity of polyethyleneimine is 99.4%, the molecular weight is 850, and the density is 1.12 g / mL.

[0053] Example 1

[0054] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0055] S1. After adjusting the pH of the oily wastewater from the kitchen to 6 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 2 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0056] S2. Mix 800 mL of pretreated oily wastewater a with 30 g of composite demulsifier, introduce air at 10 mm / s, perform air flotation treatment for 45 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0057] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0058] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0059] After sterilizing the culture medium at 95℃ for 20 min, cool it to room temperature and then add 1.5×10⁻⁶ ppm of the culture medium. 9 CFU of Bacillus XH-1 was added to 80 mL of sterilized culture medium and cultured for 15 h at a shaking speed of 170 rpm, a temperature of 30 °C, and a pH of 5 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 26:1:7:5.5:0.5:0.5:1.2:950.

[0060] The compound demulsifier is prepared by the following steps:

[0061] A1. Add 4g of corn starch to 45mL of deionized water and stir at 75℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0062] A2. Mix 35g of 1-butyl-3-methylimidazolium chloride and 1g of cellulose, stir at 75℃ until completely dissolved, add 0.02g of potassium persulfate, 0.2g of methacryloyloxyethyltrimethylammonium chloride, 0.2g of acrylamide and 0.3g of 2-acrylamido-2-methyl-1-propanesulfonic acid, stir at 80℃ for 3h, cool to room temperature, soak in 50mL of ethanol for 4h, centrifuge at 2000r / min to collect the precipitate, dry the precipitate in an oven at 50℃ for 10min to obtain modified cellulose;

[0063] A3. Add 2g of modified cellulose to 25mL of ethanol and stir well. Add 1.2g of sodium alginate and 0.6g of calcium chloride and continue stirring for 20min. Add 1g of starch-coated bacterial culture and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration. Dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0064] A4. Add 0.6g of nano carbon black and 2g of polyethyleneimine to 45mL of deionized water, place in an ultrasonic field, and sonicate at 55℃ for 6h. After filtration through a 0.22μm polytetrafluoroethylene membrane, wash with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dry at -20℃ for 1h to obtain modified nano carbon black.

[0065] A5. Add 1g of core-shell microcapsules to 25mL of Tris-HCl buffer solution with pH 8, stir well, add 0.2g of dopamine, stir for 2h, filter, wash 3 times with deionized water, and dry at room temperature to obtain dopamine-modified core-shell microcapsules; add 2g of dopamine-modified core-shell microcapsules and 1g of modified nano carbon black to 45mL of ethanol, stir and mix for 30min, filter, wash 3 times with deionized water, and dry at room temperature to obtain composite demulsifier.

[0066] Example 2

[0067] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0068] S1. The pH of the oily wastewater from the kitchen was adjusted to 7.5 using a 1 mol / L sodium hydroxide solution, and then allowed to settle for 3.5 hours. The scum was collected by skimming to obtain pretreated oily wastewater a.

[0069] S2. Mix 900 mL of pretreated oily wastewater a with 40 g of composite demulsifier, introduce air at 15 mm / s, perform air flotation treatment for 50 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0070] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0071] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0072] After sterilizing the culture medium at 100℃ for 25 min, cool it to room temperature and then add 1.5×10⁻⁶ ppm of the culture medium. 9CFU of Bacillus XH-1 was added to 100 mL of sterilized culture medium and cultured for 18 h at a shaking speed of 176 rpm, a temperature of 32 °C, and a pH of 7 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 26.5:2:8:5.8:1:1:1.4:1000.

[0073] The compound demulsifier is prepared by the following steps:

[0074] A1. Add 5g of corn starch to 50mL of deionized water and stir at 80℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0075] A2. Mix 40g of 1-butyl-3-methylimidazolium chloride and 1.3g of cellulose, stir at 80℃ until completely dissolved, add 0.03g of potassium persulfate, 0.3g of methacryloyloxyethyltrimethylammonium chloride, 0.3g of acrylamide and 0.4g of 2-acrylamido-2-methyl-1-propanesulfonic acid, stir at 80℃ for 3h, cool to room temperature, soak in 50mL of ethanol for 4h, centrifuge at 2000r / min to collect the precipitate, dry the precipitate in an oven at 50℃ for 10min to obtain modified cellulose;

[0076] A3. Add 2.5g of modified cellulose to 30mL of ethanol and stir well. Add 1.3g of sodium alginate and 0.7g of calcium chloride and continue stirring for 20min. Add 1.2g of starch-coated bacterial culture and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration and dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0077] A4. Add 0.8g of nano carbon black and 2.5g of polyethyleneimine to 50mL of deionized water, place in an ultrasonic field of 250W and 40kHz, and sonicate at 60℃ for 8h. Filter with a 0.22μm polytetrafluoroethylene membrane, wash 5 times with deionized water to remove unreacted polyethyleneimine, and freeze-dry at -20℃ to obtain modified nano carbon black.

[0078] A5. Add 2g of core-shell microcapsules to 30mL of Tris-HCl buffer solution with pH 8.5, stir well, add 0.3g of dopamine, stir for 2h, filter, wash 3 times with deionized water, and dry at room temperature to obtain dopamine-modified core-shell microcapsules; add 2.5g of dopamine-modified core-shell microcapsules and 1.2g of modified nano carbon black to 50mL of ethanol, stir and mix for 30min, filter, wash 3 times with deionized water, and dry at room temperature to obtain composite demulsifier.

[0079] Example 3

[0080] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0081] S1. After adjusting the pH of the oily wastewater from the kitchen to 9 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 5 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0082] S2. Mix 1000 mL of pretreated oily wastewater a with 50 g of composite demulsifier, introduce air at 20 mm / s, perform air flotation treatment for 55 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0083] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0084] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0085] After sterilizing the culture medium at 105℃ for 30 min, and then cooling it to room temperature, 1.5×10⁻⁶ ppm was added. 9 CFU of Bacillus XH-1 was added to 120 mL of sterilized culture medium and cultured for 20 h at a shaking speed of 180 rpm, a temperature of 35 °C, and a pH of 9 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 27:3:9:6:1.5:1.5:1.6:1050.

[0086] The compound demulsifier is prepared by the following steps:

[0087] A1. Add 6g of corn starch to 55mL of deionized water and stir at 80℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0088] A2. Mix 45g of 1-butyl-3-methylimidazolium chloride and 1.6g of cellulose, stir at 85℃ until completely dissolved, add 0.04g of potassium persulfate, 0.4g of methacryloyloxyethyltrimethylammonium chloride, 0.4g of acrylamide and 0.5g of 2-acrylamido-2-methyl-1-propanesulfonic acid, stir at 80℃ for 3h, cool to room temperature, soak in 50mL of ethanol for 4h, centrifuge at 2000r / min to collect the precipitate, dry the precipitate in an oven at 50℃ for 10min to obtain modified cellulose;

[0089] A3. Add 3g of modified cellulose to 35mL of ethanol and stir well. Add 1.4g of sodium alginate and 0.8g of calcium chloride and continue stirring for 20min. Add 1.4g of starch-coated bacterial culture and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration. Dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0090] A4. Add 1g of nano carbon black and 3g of polyethyleneimine to 55mL of deionized water, place in an ultrasonic field of 250W and 40kHz, sonicate at 65℃ for 10h, filter with a 0.22μm polytetrafluoroethylene membrane, wash with deionized water 5 times to remove unreacted polyethyleneimine, freeze dry at -20℃ to obtain modified nano carbon black;

[0091] A5. Add 3g of core-shell microcapsules to 35mL of Tris-HCl buffer solution with pH 9, stir well, add 0.4g of dopamine, stir for 2h, filter, wash 3 times with deionized water, and dry at room temperature to obtain dopamine-modified core-shell microcapsules; add 3g of dopamine-modified core-shell microcapsules and 1.4g of modified nano carbon black to 55mL of ethanol, stir and mix for 30min, filter, wash 3 times with deionized water, and dry at room temperature to obtain composite demulsifier.

[0092] Comparative Example 1

[0093] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0094] S1. After adjusting the pH of the oily wastewater from the kitchen to 9 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 5 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0095] S2. Mix 1000 mL of pretreated oily wastewater a with 50 g of composite demulsifier, introduce air at 20 mm / s, perform air flotation treatment for 55 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0096] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0097] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0098] After sterilizing the culture medium at 105℃ for 30 min, and then cooling it to room temperature, 1.5×10⁻⁶ ppm was added. 9 CFU of Bacillus XH-1 was added to 120 mL of sterilized culture medium and cultured for 20 h at a shaking speed of 180 rpm, a temperature of 35 °C, and a pH of 9 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 27:3:9:6:1.5:1.5:1.6:1050.

[0099] The compound demulsifier is prepared by the following steps:

[0100] A1. Add 6g of corn starch to 55mL of deionized water and stir at 80℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0101] A2. Add 3g of cellulose to 35mL of ethanol and stir well. Add 1.4g of sodium alginate and 0.8g of calcium chloride and continue stirring for 20min. Add 1.4g of starch-coated bacterial culture and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration and dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0102] A3. Add 1g of nano carbon black and 3g of polyethyleneimine to 55mL of deionized water, place in an ultrasonic field of 250W and 40kHz, sonicate at 65℃ for 10h, filter with a 0.22μm polytetrafluoroethylene membrane, wash with deionized water 5 times to remove unreacted polyethyleneimine, freeze dry at -20℃ to obtain modified nano carbon black;

[0103] A4. Add 3g of core-shell microcapsules to 35mL of Tris-HCl buffer solution with pH 9, stir well, add 0.4g of dopamine, stir for 2h, filter, wash 3 times with deionized water, and dry at room temperature to obtain dopamine-modified core-shell microcapsules; add 3g of dopamine-modified core-shell microcapsules and 1.4g of modified nano carbon black to 55mL of ethanol, stir and mix for 30min, filter, wash 3 times with deionized water, and dry at room temperature to obtain composite demulsifier.

[0104] Comparative Example 2

[0105] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0106] S1. After adjusting the pH of the oily wastewater from the kitchen to 9 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 5 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0107] S2. Mix 1000 mL of pretreated oily wastewater a with 50 g of composite demulsifier, introduce air at 20 mm / s, perform air flotation treatment for 55 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0108] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0109] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0110] After sterilizing the culture medium at 105℃ for 30 min, and then cooling it to room temperature, 1.5×10⁻⁶ ppm was added. 9 CFU of Bacillus XH-1 was added to 120 mL of sterilized culture medium and cultured for 20 h at a shaking speed of 180 rpm, a temperature of 35 °C, and a pH of 9 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 27:3:9:6:1.5:1.5:1.6:1050.

[0111] The compound demulsifier is prepared by the following steps:

[0112] A1. Mix 45g of 1-butyl-3-methylimidazolium chloride and 1.6g of cellulose, stir at 85℃ until completely dissolved, add 0.04g of potassium persulfate, 0.4g of methacryloyloxyethyltrimethylammonium chloride, 0.4g of acrylamide and 0.5g of 2-acrylamido-2-methyl-1-propanesulfonic acid, stir at 80℃ for 3h, cool to room temperature, soak in 50mL of ethanol for 4h, centrifuge at 2000r / min to collect the precipitate, dry the precipitate in an oven at 50℃ for 10min to obtain modified cellulose;

[0113] A2. Add 3g of modified cellulose to 35mL of ethanol and stir well. Add 1.4g of sodium alginate and 0.8g of calcium chloride and continue stirring for 20min. Add 1.4g of Bacillus XH-1 bacterial solution and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration and dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0114] A3. Add 1g of nano carbon black and 3g of polyethyleneimine to 55mL of deionized water, place in an ultrasonic field of 250W and 40kHz, sonicate at 65℃ for 10h, filter with a 0.22μm polytetrafluoroethylene membrane, wash with deionized water 5 times to remove unreacted polyethyleneimine, freeze dry at -20℃ to obtain modified nano carbon black;

[0115] A4. Add 3g of core-shell microcapsules to 35mL of Tris-HCl buffer solution with pH 9, stir well, add 0.4g of dopamine, stir for 2h, filter, wash 3 times with deionized water, and dry at room temperature to obtain dopamine-modified core-shell microcapsules; add 3g of dopamine-modified core-shell microcapsules and 1.4g of modified nano carbon black to 55mL of ethanol, stir and mix for 30min, filter, wash 3 times with deionized water, and dry at room temperature to obtain composite demulsifier.

[0116] Comparative Example 3

[0117] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0118] S1. After adjusting the pH of the oily wastewater from the kitchen to 9 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 5 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0119] S2. Mix 1000 mL of pretreated oily wastewater a with 50 g of composite demulsifier, introduce air at 20 mm / s, perform air flotation treatment for 55 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0120] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0121] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0122] After sterilizing the culture medium at 105℃ for 30 min, and then cooling it to room temperature, 1.5×10⁻⁶ ppm was added. 9 CFU of Bacillus XH-1 was added to 120 mL of sterilized culture medium and cultured for 20 h at a shaking speed of 180 rpm, a temperature of 35 °C, and a pH of 9 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 27:3:9:6:1.5:1.5:1.6:1050.

[0123] The compound demulsifier is prepared by the following steps:

[0124] A1. Add 6g of corn starch to 55mL of deionized water and stir at 80℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0125] A2. Add 1g of nano carbon black and 3g of polyethyleneimine to 55mL of deionized water, place in an ultrasonic field of 250W and 40kHz, and sonicate at 65℃ for 10h. Filter with a 0.22μm polytetrafluoroethylene membrane, wash with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dry at -20℃ to obtain modified nano carbon black.

[0126] A3. Add 3g of starch-coated bacterial culture to 35mL of Tris-HCl buffer solution with pH 9, stir well, add 0.4g of dopamine, stir for 2h, filter, wash 3 times with deionized water, and dry at room temperature to obtain a solid; add 3g of solid and 1.4g of modified nano carbon black to 55mL of ethanol, stir and mix for 30min, filter, wash 3 times with deionized water, and dry at room temperature to obtain a composite demulsifier.

[0127] Comparative Example 4

[0128] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0129] S1. After adjusting the pH of the oily wastewater from the kitchen to 9 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 5 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0130] S2. Mix 1000 mL of pretreated oily wastewater a with 50 g of core-shell microcapsules, introduce air at 20 mm / s, perform air flotation treatment for 55 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0131] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0132] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0133] After sterilizing the culture medium at 105℃ for 30 min, and then cooling it to room temperature, 1.5×10⁻⁶ ppm was added. 9CFU of Bacillus XH-1 was added to 120 mL of sterilized culture medium and cultured for 20 h at a shaking speed of 180 rpm, a temperature of 35 °C, and a pH of 9 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 27:3:9:6:1.5:1.5:1.6:1050.

[0134] The compound demulsifier is prepared by the following steps:

[0135] A1. Add 6g of corn starch to 55mL of deionized water and stir at 80℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0136] A2. Mix 45g of 1-butyl-3-methylimidazolium chloride and 1.6g of cellulose, stir at 85℃ until completely dissolved, add 0.04g of potassium persulfate, 0.4g of methacryloyloxyethyltrimethylammonium chloride, 0.4g of acrylamide and 0.5g of 2-acrylamido-2-methyl-1-propanesulfonic acid, stir at 80℃ for 3h, cool to room temperature, soak in 50mL of ethanol for 4h, centrifuge at 2000r / min to collect the precipitate, dry the precipitate in an oven at 50℃ for 10min to obtain modified cellulose;

[0137] A3. Add 3g of modified cellulose to 35mL of ethanol and stir well. Add 1.4g of sodium alginate and 0.8g of calcium chloride and continue stirring for 20min. Add 1.4g of starch-coated bacterial culture and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration and dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0138] Comparative Example 5

[0139] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0140] S1. After adjusting the pH of the oily wastewater from the kitchen to 9 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 5 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0141] S2. Mix 1000 mL of pretreated oily wastewater a with 50 g of composite demulsifier, introduce air at 20 mm / s, perform air flotation treatment for 55 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0142] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0143] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0144] After sterilizing the culture medium at 105℃ for 30 min, and then cooling it to room temperature, 1.5×10⁻⁶ ppm was added. 9 CFU of Bacillus XH-1 was added to 120 mL of sterilized culture medium and cultured for 20 h at a shaking speed of 180 rpm, a temperature of 35 °C, and a pH of 9 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 27:3:9:6:1.5:1.5:1.6:1050.

[0145] The compound demulsifier is prepared by the following steps:

[0146] A1. Add 6g of corn starch to 55mL of deionized water and stir at 80℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0147] A2. Mix 45g of 1-butyl-3-methylimidazolium chloride and 1.6g of cellulose, stir at 85℃ until completely dissolved, add 0.04g of potassium persulfate, 0.4g of methacryloyloxyethyltrimethylammonium chloride, 0.4g of acrylamide and 0.5g of 2-acrylamido-2-methyl-1-propanesulfonic acid, stir at 80℃ for 3h, cool to room temperature, soak in 50mL of ethanol for 4h, centrifuge at 2000r / min to collect the precipitate, dry the precipitate in an oven at 50℃ for 10min to obtain modified cellulose;

[0148] A3. Add 3g of modified cellulose to 35mL of ethanol and stir well. Add 1.4g of sodium alginate and 0.8g of calcium chloride and continue stirring for 20min. Add 1.4g of starch-coated bacterial culture and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration. Dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0149] A4. Add 1g of nano carbon black and 3g of polyethyleneimine to 55mL of deionized water, place in an ultrasonic field of 250W and 40kHz, sonicate at 65℃ for 10h, filter with a 0.22μm polytetrafluoroethylene membrane, wash with deionized water 5 times to remove unreacted polyethyleneimine, freeze dry at -20℃ to obtain modified nano carbon black;

[0150] A5. Add 3g of core-shell microcapsules and 1.4g of modified nano carbon black to 55mL of ethanol, stir and mix for 30min, filter, wash 3 times with deionized water, and dry at room temperature to obtain a composite demulsifier.

[0151] Comparative Example 6

[0152] A process for treating oily wastewater from kitchens based on demulsifiers includes the following steps:

[0153] S1. After adjusting the pH of the oily wastewater from the kitchen to 9 with a sodium hydroxide solution of 1 mol / L, the wastewater was allowed to settle for 5 hours. The scum was then skimmed off to obtain pretreated oily wastewater a.

[0154] S2. Mix 1000 mL of pretreated oily wastewater a with 50 g of dopamine-modified core-shell microcapsules, introduce air at 20 mm / s, perform air flotation treatment for 55 min, skim off the scum and collect the suspended solids to obtain pretreated oily wastewater b.

[0155] S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse.

[0156] Bacillus XH-1 bacterial culture was prepared by the following steps:

[0157] After sterilizing the culture medium at 105℃ for 30 min, and then cooling it to room temperature, 1.5×10⁻⁶ ppm was added. 9 CFU of Bacillus XH-1 was added to 120 mL of sterilized culture medium and cultured for 20 h at a shaking speed of 180 rpm, a temperature of 35 °C, and a pH of 9 to obtain Bacillus XH-1 bacterial suspension. The culture medium was prepared by mixing wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of 27:3:9:6:1.5:1.5:1.6:1050.

[0158] The compound demulsifier is prepared by the following steps:

[0159] A1. Add 6g of corn starch to 55mL of deionized water and stir at 80℃ until the starch is completely gelatinized. Cool to room temperature, add 5mL of Bacillus XH-1 bacterial solution, stir for 30min to ensure that the bacterial culture is fully in contact with the starch, and dry at room temperature overnight to obtain starch-coated bacterial culture.

[0160] A2. Mix 45g of 1-butyl-3-methylimidazolium chloride and 1.6g of cellulose, stir at 85℃ until completely dissolved, add 0.04g of potassium persulfate, 0.4g of methacryloyloxyethyltrimethylammonium chloride, 0.4g of acrylamide and 0.5g of 2-acrylamido-2-methyl-1-propanesulfonic acid, stir at 80℃ for 3h, cool to room temperature, soak in 50mL of ethanol for 4h, centrifuge at 2000r / min to collect the precipitate, dry the precipitate in an oven at 50℃ for 10min to obtain modified cellulose;

[0161] A3. Add 3g of modified cellulose to 35mL of ethanol and stir well. Add 1.4g of sodium alginate and 0.8g of calcium chloride and continue stirring for 20min. Add 1.4g of starch-coated bacterial culture and sonicate at 120W and 25℃ for 1.5h to eliminate bubbles. Obtain the solid by vacuum filtration. Dry the solid at 30℃ for 2h to obtain core-shell microcapsules.

[0162] A4. Add 1g of nano carbon black and 3g of polyethyleneimine to 55mL of deionized water, place in an ultrasonic field of 250W and 40kHz, sonicate at 65℃ for 10h, filter with a 0.22μm polytetrafluoroethylene membrane, wash with deionized water 5 times to remove unreacted polyethyleneimine, freeze dry at -20℃ to obtain modified nano carbon black;

[0163] A5. Add 3g of core-shell microcapsules to 35mL of Tris-HCl buffer solution with pH 9, stir well, add 0.4g of dopamine, stir for 2h, filter, wash 3 times with deionized water, and dry at room temperature to obtain dopamine-modified core-shell microcapsules.

[0164] The various indicators of the oily wastewater from the kitchens treated in Examples 1-3 and Comparative Examples 1-6 were tested.

[0165] The indicators of the oily kitchen wastewater used in Examples 1-3 and Comparative Examples 1-6 of this invention are as follows: Chemical oxygen demand (COD) 93 g / L, oil content 15.5 g / L, and ammonium nitrogen (NH4+) content 15.5 g / L. + The concentrations of total nitrogen (TN) and total phosphorus (TP) were 345 mg / L, 1950 mg / L, and 84.5 mg / L, respectively, with a pH of 4.

[0166] Determination of nitrogen and phosphorus content in the filtrate of step S3: The filtrate of step S3 was measured using Nessler's reagent spectrophotometry and ascorbic acid method, respectively, and the NH4 content in the filtrate was calculated. + The concentrations of -N and TN.

[0167] Determination of total nitrogen content in the filtrate of step S3: The total nitrogen content in the filtrate of step S3 was determined according to the national standard HJ636-2012.

[0168] The content of oil and chemical oxygen demand (COD) in the filtrate of step S3 was determined using the method described in the 4th edition of "Water and Wastewater Monitoring and Analysis Methods" published by the Editorial Board of the State Environmental Protection Administration. The results are shown in Table 1 below.

[0169] Table 1. Various indicators of oily wastewater from kitchen wastewater treated in Examples 1-3 and Comparative Examples 1-6.

[0170]

[0171] As can be seen from the data in Table 1, all indicators of the oily wastewater from the kitchen after treatment in Examples 1-3 meet the Class A standard of GB / T31962 "Water Quality Standard for Wastewater Discharge into Urban Sewers", and can be directly discharged.

[0172] In Comparative Example 1, the modified cellulose was replaced with a composite demulsifier prepared from cellulose and used for the treatment of oily wastewater from kitchens. The removal efficiency of nitrogen and phosphorus in the filtrate decreased, which proved that the introduction of quaternary ammonium groups, amide groups and sulfonic acid groups as active adsorption functional groups on the cellulose molecular chain can adsorb nitrogen and phosphorus elements in oily wastewater from kitchens, thereby removing nitrogen and phosphorus elements from the oily wastewater from kitchens and making the oily wastewater meet the release standards.

[0173] In Comparative Example 2, the starch-coated bacteria were replaced with a composite demulsifier prepared from Bacillus XH-1 bacterial solution. When used to treat oily wastewater from kitchens, the treatment effect decreased. This demonstrates that coating Bacillus XH-1 bacterial solution with corn starch can improve the stability of Bacillus XH-1 bacterial solution in oily wastewater from kitchens, and avoid the susceptibility of Bacillus XH-1 bacteria to the effects of pH and temperature in oily wastewater, which could lead to the failure of the demulsifier.

[0174] In Comparative Example 3, replacing the core-shell microcapsules with a composite demulsifier prepared from starch-coated microorganisms resulted in a decrease in treatment efficiency for oily kitchen wastewater. This indicates that using a mixture of modified cellulose, sodium alginate, and calcium chloride as the wall material and starch-coated microorganisms as the core material to prepare core-shell microcapsules further improves the stability of starch-coated microorganisms in oily kitchen wastewater and increases the treatment efficiency of oily kitchen wastewater.

[0175] In Comparative Example 4, the composite demulsifier was replaced with core-shell microcapsules for the treatment of oily wastewater from kitchens. The treatment effect decreased, which proved that modified nano-carbon black can replace the interfacial film on the surface of oil-in-water emulsions, causing oil droplets to aggregate and precipitate. It has a synergistic effect with Bacillus XH-1 in terms of demulsification performance, improving demulsification efficiency. Furthermore, modified nano-carbon black can electrostatically bind with modified carboxymethyl cellulose, causing the adsorbed modified carboxymethyl cellulose to flocculate and settle along with the modified nano-carbon black, and be removed by filtration.

[0176] In Comparative Example 5, replacing the dopamine-modified core-shell microcapsules with a composite demulsifier prepared from core-shell microcapsules resulted in a decrease in treatment efficiency for oily wastewater from kitchens. This indicates that the dopamine-modified core-shell microcapsules enable the core-shell microcapsules to chemically bond with modified nano-carbon black to form a composite demulsifier, thus increasing the treatment efficiency.

[0177] In Comparative Example 6, the composite demulsifier was replaced with dopamine-modified core-shell microcapsules for the treatment of oily wastewater from kitchens. The treatment effect decreased, which proved that the modified nano-carbon black adhered to the surface of the dopamine-modified core-shell microcapsules. The modified nano-carbon black can interact with the surface interfacial film of the oil-in-water emulsion through π-π interaction, which allows the composite demulsifier to adhere to the surface of the oil-in-water emulsion, thereby completing the demulsification and causing a large number of oil droplets to aggregate, thus removing the grease.

[0178] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0179] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A process for treating oily wastewater from kitchens based on demulsifiers, characterized in that, Includes the following steps: S1. After adjusting the pH of the oily wastewater from the kitchen to 6-9, let it stand for 2-5 hours to settle, and collect the scum by skimming to obtain pretreated oily wastewater a; S2. Mix the pretreated oily wastewater a with the composite demulsifier, introduce air at 10-20 mm / s, perform air flotation treatment for 45-55 min, skim off the scum and collect the suspended solids to obtain the pretreated oily wastewater b. S3. Filter the pretreated oily wastewater b, collect the filtrate and precipitate, and recycle and test the filtrate for reuse. The composite demulsifier is obtained by modifying core-shell microcapsules with dopamine and then mixing them with modified nano carbon black. The core-shell microcapsules are prepared by using a mixture of modified cellulose, sodium alginate and calcium chloride as the wall material and starch-coated microorganisms as the core material. The modified cellulose is obtained by reacting cellulose, methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid.

2. The process for treating oily wastewater from kitchens based on demulsifiers according to claim 1, characterized in that, The composite demulsifier is prepared by the following steps: A1. Add corn starch to deionized water and stir at 75-85℃ until the starch is completely gelatinized. Cool to room temperature, add Bacillus XH-1 bacterial solution, stir for 30 minutes, and dry at room temperature overnight to obtain starch-coated bacterial strain. A2. Mix 1-butyl-3-methylimidazolium chloride and cellulose, stir and dissolve at 75-85℃, add potassium persulfate, methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid. After the reaction is complete, cool to room temperature, soak in ethanol, centrifuge and dry to obtain modified cellulose. A3. Add modified cellulose to ethanol, stir evenly, add sodium alginate and calcium chloride, stir evenly, add starch-coated bacteria, sonicate, and then vacuum filter to obtain a solid. After drying the solid, obtain core-shell microcapsules. A4. Add nano carbon black and polyethyleneimine to deionized water, place in an ultrasonic field, and ultrasonically treat at 55-65℃ for 6-10 hours. After filtration, washing, and freeze-drying, modified nano carbon black is obtained. A5. The core-shell microcapsules were added to Tris-HCl buffer solution with pH 8-9, stirred evenly, and then dopamine was added. After the reaction was completed, the microcapsules were filtered, washed, and dried to obtain dopamine-modified core-shell microcapsules. Dopamine-modified core-shell microcapsules and modified nano-carbon black were added to ethanol, stirred evenly, filtered, washed, and dried to obtain a composite demulsifier.

3. The process for treating oily wastewater from kitchens based on demulsifiers according to claim 2, characterized in that, In step A1, the Bacillus XH-1 bacterial suspension is prepared by the following steps: sterilizing the culture medium at 95-105℃ for 20-30 min, cooling it to room temperature, adding Bacillus XH-1 bacteria to the sterilized culture medium, and culturing it at a shaking speed of 170-180 rpm, a temperature of 30-35℃, and a pH of 5-9 for 15-20 h to obtain the Bacillus XH-1 bacterial suspension.

4. The process for treating oily wastewater from kitchens based on demulsifiers according to claim 3, characterized in that, The culture medium is composed of wheat bran, soybean meal, frying waste oil, dipotassium hydrogen phosphate, calcium chloride, ferrous sulfate heptahydrate, ethylenediaminetetraacetic acid, and deionized water in a mass ratio of (26-27):(1-3):(7-9):(5.5-6):(0.5-1.5):(0.5-1.5):(1.2-1.6):(950-1050).

5. The process for treating oily wastewater from kitchens based on demulsifiers according to claim 2, characterized in that, In step A2, the mass ratio of 1-butyl-3-methylimidazolium chloride, cellulose, potassium persulfate, methacryloyloxyethyltrimethylammonium chloride, acrylamide, and 2-acrylamido-2-methyl-1-propanesulfonic acid is (35-45):(1-1.6):(0.02-0.04):(0.2-0.4):(0.2-0.4):(0.3-0.5).

6. The process for treating oily kitchen wastewater based on demulsifiers according to claim 2, characterized in that, In step A3, the ratio of the amount of modified cellulose, ethanol, sodium alginate, calcium chloride, and starch-coated bacteria is (2-3)g:(25-35)mL:(1.2-1.4)g:(0.6-0.8)g:(1-1.4)g.

7. The process for treating oily wastewater from kitchens based on demulsifiers according to claim 2, characterized in that, In step A4, the ratio of nano-carbon black, polyethyleneimine, and deionized water is (0.6-1)g:(2-3)g:(45-55)mL.

8. The process for treating oily wastewater from kitchens based on demulsifiers according to claim 2, characterized in that, In step A5, the ratio of the core-shell microcapsules, Tris-HCl buffer, and dopamine is (1-3)g:(25-35)mL:(0.2-0.4)g; In step A5, the ratio of dopamine-modified core-shell microcapsules, modified nano-carbon black, and ethanol is (2-3)g:(1-1.4)g:(45-55)mL.

Images