Kitchen oily wastewater treatment process based on demulsifying bacteria

Abstract

The invention relates to the technical field of oily wastewater treatment, and discloses a kitchen oily wastewater treatment process based on demulsifying bacteria, which comprises the following steps: adjusting the pH value of kitchen oily wastewater to 6-9, standing and settling, skimming and collecting scum to obtain pretreated oily wastewater a; mixing the pretreated oily wastewater a with a composite demulsifier, introducing air at the speed of 10-20 mm / s, carrying out air flotation treatment for 45-55 minutes, skimming, and collecting suspended matters, so as to obtain pretreated oily wastewater b; and filtering the pretreated oily wastewater b, collecting filtrate and precipitates, and recovering, detecting and reusing the filtrate. The composite demulsifier can improve the stability of the strain in the kitchen oily wastewater and improve the treatment efficiency of the kitchen oily wastewater, and after the composite demulsifier absorbs water, swells and breaks, the modified nano carbon black can be combined with the modified carboxymethyl cellulose through static electricity, so that the composite demulsifier can be used for treating the kitchen oily wastewater. The adsorbed modified carboxymethyl cellulose is flocculated and settled along with the modified nano carbon black, and is removed through filtration.

Description

Technical Field

[0001] The invention relates to the technical field of oily wastewater treatment, and in particular to a process for treating oily kitchen wastewater based on demulsifiers. Background Art

[0002] Oily wastewater is a pollution source that has attracted attention at home and abroad. It is mainly produced by the catering industry, food processing industry, gas generation stations, mechanical processing, car washing industry and other channels, which is harmful to water bodies, soil and human body. Among them, oily wastewater from catering kitchens can produce strong odor, high oil content, and a large amount of plant fiber and detergent. Oil is easy to produce a large amount of free fatty acids. The double-layer structure of these free fatty acids will be aggregated and compressed by metal ions in the sewage, solidified and accumulated on the wall of the drainage pipe, causing pipe blockage. Therefore, it is necessary to remove the oil in the oily wastewater from catering kitchens.

[0003] Methods for removing oily wastewater include physical, chemical, and biological methods. Among them, biological methods have the characteristics of large processing capacity, easy control, economic feasibility, and no secondary pollution. Demulsifiers or their metabolic processes and metabolites are used to decompose organic matter in oily wastewater and remove grease from oily wastewater from restaurant kitchens, thereby promoting oil-water separation and improving the treatment efficiency of oily wastewater from restaurant kitchens. However, demulsifiers are easily affected by the pH and temperature of oily wastewater, which leads to the failure of demulsifiers and affects the treatment efficiency of oily wastewater. In addition, there are a large number of surfactant compounds on the surface of the water-in-oil emulsion in the 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] The present invention provides a process for treating oily kitchen wastewater based on demulsifying bacteria, which solves the problems that demulsifying bacteria fail in oily wastewater and a rigid film exists on the surface of oil-in-water emulsion in oily wastewater to hinder the aggregation and precipitation of oil droplets.

[0005] The technical solution of the present invention:

[0006] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0007] S1. After adjusting the pH of the kitchen oily wastewater to 6-9, the wastewater was allowed to settle for 2-5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a;

[0008] S2. The pretreated oily wastewater a is mixed with a composite demulsifier, air is introduced at 10-20 mm / s, and flotation treatment is performed for 45-55 min, and the suspended matter is skimmed and collected to obtain pretreated oily wastewater b;

[0009] S3. The pretreated oily wastewater b is filtered, the filtrate and the precipitate are collected, and the filtrate is recovered for testing and 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 mixing modified cellulose, sodium alginate and calcium chloride as wall materials and starch-coated bacteria as core materials;

[0012] The modified cellulose is obtained by mixed reaction of cellulose, methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamide-2-methyl-1-propane sulfonic acid.

[0013] Furthermore, the chemical oxygen demand (COD) of restaurant oily wastewater is 90-95 g / L, the oil content is 15-16 g / L, and the ammonium nitrogen (NH 4 + -N) is 325-365 mg / L, total nitrogen (TN) is 1848-2000 mg / L, total phosphorus (TP) is 83.5-88.6 mg / L, and pH is 3.5-4.3.

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

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

[0016] A1. Add corn starch to deionized water, stir at 75-85°C 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 bacteria;

[0017] A2. 1-butyl-3-methylimidazole chloride and cellulose are mixed, stirred and dissolved at 75-85° C., potassium persulfate, methacryloyloxyethyl trimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propane sulfonic acid are added, and after the reaction is completed, the mixture is cooled to room temperature, soaked in ethanol, centrifuged and dried to obtain modified cellulose;

[0018] A3. The modified cellulose was added to ethanol, stirred evenly, sodium alginate and calcium chloride were added, stirred evenly, starch-coated bacteria were added, and after ultrasonic treatment, a solid was obtained by vacuum filtration. After the solid was dried, core-shell microcapsules were obtained;

[0019] A4. Add nano carbon black and polyethyleneimine to deionized water, place in an ultrasonic field, and ultrasonically treat at 55-65°C for 6-10h, filter, wash, and freeze-dry to obtain modified nano carbon black;

[0020] A5. Add the core-shell microcapsules to Tris-HCl buffer with a pH of 8-9, stir evenly, add dopamine, and after the reaction is completed, filter, wash, and dry to obtain dopamine-modified core-shell microcapsules; add the dopamine-modified core-shell microcapsules and modified nano-carbon black to ethanol, stir evenly, filter, wash, and dry to obtain a composite demulsifier.

[0021] Furthermore, during the above-mentioned A1 reaction, the hydroxyl groups in the gelatinized corn starch can combine with the Bacillus XH-1 bacterial solution through hydrogen bonds, and the starch has good adhesion and film-forming properties, so that the Bacillus XH-1 bacterial solution can penetrate into the gelatinized corn starch, and then can effectively wrap the bacteria to form a starch inclusion complex, that is, a starch-coated bacteria.

[0022] Furthermore, in the above-mentioned A2 reaction process, potassium persulfate is used as an initiator, and the hydroxyl groups on the glucose units in the cellulose can undergo a graft copolymerization reaction with the double bonds of methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamide-2-methyl-1-propane sulfonic acid, thereby introducing quaternary ammonium groups, amide groups and sulfonic acid groups as active adsorption functional groups on the cellulose molecular chain to form modified cellulose.

[0023] Furthermore, in the above-mentioned A3 reaction process, modified cellulose, sodium alginate and calcium chloride are mixed as wall materials, and starch-coated bacteria are used as core materials. The calcium ions in calcium chloride can be compounded and cross-linked with modified cellulose and sodium alginate, so that the starch-coated bacteria are embedded in the microcapsule system to form core-shell microcapsules.

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

[0025] Furthermore, during the above-mentioned reaction A5, in the Tris-HCl buffer, dopamine can self-polymerize on the surface of the core-shell microcapsule to form polydopamine, so that the surface of the core-shell microcapsule contains a large number of phenolic hydroxyl groups, which can be combined with the modified nano-carbon black through chemical bonds, so that the modified nano-carbon black adheres to the surface of the core-shell microcapsule to 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] Furthermore, in step A2, the mass ratio of 1-butyl-3-methylimidazole chloride, cellulose, potassium persulfate, methacryloyloxyethyltrimethylammonium chloride, acrylamide, and 2-acrylamido-2-methyl-1-propane sulfonic acid is (35-45):(1-1.6):(0.02-0.04):(0.2-0.4):(0.2-0.4):(0.3-0.5).

[0028] Furthermore, in step A3, the dosage ratio of the 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] Furthermore, in step A4, the ratio of the nano carbon black, polyethyleneimine and deionized water is (0.6-1) g: (2-3) g: (45-55) mL.

[0030] Furthermore, 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] Furthermore, in step A5, the dopamine modified core-shell microcapsules, modified nano carbon black, and ethanol are used in a ratio of (2-3) g: (1-1.4) g: (45-55) mL.

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

[0033] Furthermore, the culture medium is prepared by mixing wheat bran, bean cake powder, waste frying 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 waste frying oil is obtained by frying soybean oil at 180-220° C. for 10-12 hours.

[0035] Furthermore, the bean cake powder is soybean cake powder.

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

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

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

[0039] (1) In the technical scheme of the present invention, Bacillus XH-1 has biodegradability, can decompose the interfacial film on the surface of the water-in-oil emulsion in the oily wastewater from the restaurant, has a good demulsification effect, causes the oil droplets to aggregate and precipitate, thereby promoting oil-water separation, and Bacillus XH-1 can also decompose the grease, organic matter, and inorganic matter in the oily wastewater from the restaurant, reduce the nitrogen content and grease content in the wastewater, and improve the treatment efficiency of the oily wastewater from the restaurant; corn starch is used to coat the Bacillus XH-1 bacterial liquid, which can improve the stability of the Bacillus XH-1 bacterial liquid in the oily wastewater from the restaurant, and avoid the Bacillus XH-1 bacteria being easily affected by the pH and temperature of the oily wastewater, resulting in the failure of the demulsification bacteria, and the starch can also provide a carbon source for the Bacillus XH-1 bacteria, thereby improving the activity and stability of the Bacillus XH-1 bacteria and increasing the removal efficiency of the oily wastewater from the restaurant.

[0040] (2) In the technical scheme of the present invention, cellulose can undergo graft copolymerization reaction with the double bonds of methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propane sulfonic acid to form modified cellulose, and quaternary ammonium, amide and sulfonic acid active adsorption functional groups are introduced into the cellulose molecular chain, which can adsorb nitrogen and phosphorus elements in the oily wastewater of restaurant kitchens, thereby completing the removal of nitrogen and phosphorus elements in the oily wastewater of restaurant kitchens, and making the oily wastewater of restaurant kitchens meet the releasable standard; polyethyleneimine is grafted onto the surface of nano-carbon black, and the modified nano-carbon black can replace the interfacial film on the surface of the oil-in-water emulsion, so that the oil droplets aggregate and precipitate, and has a synergistic effect with Bacillus XH-1 bacteria in terms of demulsification performance, thereby improving the demulsification efficiency and the efficiency of treating the oily wastewater of restaurant kitchens.

[0041] (3) In the technical scheme of the present invention, modified cellulose, sodium alginate and calcium chloride are mixed as wall materials, and starch-coated bacteria are used as core materials to prepare core-shell microcapsules. The formed core-shell microcapsules have high stability, which further improves the stability of starch-coated bacteria in oily wastewater and improves the treatment efficiency of oily wastewater. 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 the oily wastewater. After the surface of the core-shell microcapsules absorbs water, the oily wastewater enters the core-shell microcapsules and contacts with the starch-coated bacteria, thereby decomposing the interfacial film on the surface of the water-in-oil emulsion in the oily wastewater and completing the demulsification.

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

[0043] (5) In the technical scheme of the present invention, after the composite demulsifier absorbs water, swells and ruptures, the released polyethyleneimine on the surface of the modified nano-carbon black carries a positive charge and can be electrostatically bonded to the hydroxyl groups in the modified carboxymethyl cellulose after adsorbing ammonia and phosphorus in the wastewater, so that the modified carboxymethyl cellulose that has been adsorbed is flocculated and precipitated along with the modified nano-carbon black and can be removed by filtration. In addition, the raw materials used in the composite demulsifier are all degradable to avoid harm to the water quality. DETAILED DESCRIPTION

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The raw materials used in the examples of the present invention are as follows, and all reagents used are of analytical grade.

[0046] Among them, a sodium hydroxide solution with a concentration of 1 mol / L is used to adjust the pH of the oily kitchen wastewater.

[0047] Bacillus XH-1: The deposit number is CGMCC No.5460.

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

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

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

[0051] The purity of 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 kitchen wastewater based on demulsifiers comprises the following steps:

[0055] S1. The pH of the kitchen oily wastewater was adjusted to 6 using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 2 h. The scum was collected by skimming to obtain pretreated oily wastewater a;

[0056] S2. 800 mL of pretreated oily wastewater a was mixed with 30 g of composite demulsifier, air was introduced at 10 mm / s, and flotation treatment was performed for 45 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0058] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0059] The culture medium was sterilized at 95°C for 20 min, cooled to room temperature, and 1.5 × 10 9 CFU Bacillus XH-1 bacteria are added to 80 mL of sterilized culture medium, and cultured for 15 hours at a shaking speed of 170 rpm, a temperature of 30°C, and a pH of 5 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0061] A1. Add 4 g corn starch to 45 mL deionized water, stir at 75 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact with the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0062] A2. 35 g of 1-butyl-3-methylimidazole chloride and 1 g of cellulose were mixed and stirred at 75° C. until completely dissolved, 0.02 g of potassium persulfate, 0.2 g of methacryloyloxyethyl trimethylammonium chloride, 0.2 g of acrylamide and 0.3 g of 2-acrylamido-2-methyl-1-propane sulfonic acid were added, and the mixture was stirred at 80° C. for 3 h, cooled to room temperature, and immersed in 50 mL of ethanol for 4 h. The precipitate was collected by centrifugation at 2000 r / min, and the precipitate was dried in an oven at 50° C. for 10 min to obtain modified cellulose;

[0063] A3. Add 2 g of modified cellulose to 25 mL of ethanol, stir evenly, add 1.2 g of sodium alginate and 0.6 g of calcium chloride, continue stirring for 20 min, add 1 g of starch-coated bacteria, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, vacuum filter to obtain a solid, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules;

[0064] A4. 0.6 g of nano carbon black and 2 g of polyethyleneimine were added to 45 mL of deionized water, placed in an ultrasonic field, and ultrasonically treated at 55°C for 6 h. After filtering with a 0.22 μm polytetrafluoroethylene membrane, the mixture was washed with deionized water for 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20°C for 1 h to obtain modified nano carbon black.

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

[0066] Example 2

[0067] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

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

[0069] S2. 900 mL of pretreated oily wastewater a was mixed with 40 g of composite demulsifier, air was introduced at 15 mm / s, and flotation treatment was performed for 50 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0071] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0072] The culture medium was sterilized at 100°C for 25 min, cooled to room temperature, and 1.5 × 10 9CFU Bacillus XH-1 bacteria are added to 100 mL of sterilized culture medium, and cultured for 18 hours at a shaking speed of 176 rpm, a temperature of 32° C., and a pH of 7 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0074] A1. Add 5 g corn starch to 50 mL deionized water, stir at 80 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0075] A2. 40 g of 1-butyl-3-methylimidazole chloride and 1.3 g of cellulose were mixed and stirred at 80° C. until completely dissolved, 0.03 g of potassium persulfate, 0.3 g of methacryloyloxyethyl trimethylammonium chloride, 0.3 g of acrylamide and 0.4 g of 2-acrylamido-2-methyl-1-propane sulfonic acid were added, and the mixture was stirred at 80° C. for 3 h, cooled to room temperature, and soaked in 50 mL of ethanol for 4 h. The precipitate was collected by centrifugation at 2000 r / min, and the precipitate was dried in an oven at 50° C. for 10 min to obtain modified cellulose;

[0076] A3. Add 2.5 g of modified cellulose to 30 mL of ethanol, stir evenly, add 1.3 g of sodium alginate and 0.7 g of calcium chloride, continue stirring for 20 min, add 1.2 g of starch-coated bacteria, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, vacuum filter to obtain a solid, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules;

[0077] A4. 0.8 g of nano carbon black and 2.5 g of polyethyleneimine were added to 50 mL of deionized water, placed in an ultrasonic field of 250 W, 40 kHz, and ultrasonically treated at 60 ° C for 8 h, filtered with a 0.22 μm polytetrafluoroethylene membrane, washed with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20 ° C to obtain modified nano carbon black;

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

[0079] Example 3

[0080] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0081] S1. The pH of the kitchen oily wastewater was adjusted to 9 using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a;

[0082] S2. 1000 mL of pretreated oily wastewater a was mixed with 50 g of composite demulsifier, air was introduced at 20 mm / s, and flotation treatment was performed for 55 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0084] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0085] The culture medium was sterilized at 105°C for 30 min, cooled to room temperature, and 1.5 × 10 9 CFU Bacillus XH-1 bacteria are added to 120 mL of sterilized culture medium, and cultured for 20 hours at a shaking speed of 180 rpm, a temperature of 35°C, and a pH of 9 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0087] A1. Add 6 g corn starch to 55 mL deionized water, stir at 80 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact with the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0088] A2. 45 g of 1-butyl-3-methylimidazole chloride and 1.6 g of cellulose were mixed and stirred at 85° C. until completely dissolved, 0.04 g of potassium persulfate, 0.4 g of methacryloyloxyethyl trimethylammonium chloride, 0.4 g of acrylamide and 0.5 g of 2-acrylamido-2-methyl-1-propane sulfonic acid were added, and the mixture was stirred at 80° C. for 3 h, cooled to room temperature, and immersed in 50 mL of ethanol for 4 h. The precipitate was collected by centrifugation at 2000 r / min, and the precipitate was dried in an oven at 50° C. for 10 min to obtain modified cellulose;

[0089] A3. Add 3 g of modified cellulose to 35 mL of ethanol, stir evenly, add 1.4 g of sodium alginate and 0.8 g of calcium chloride, continue stirring for 20 min, add 1.4 g of starch-coated bacteria, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, vacuum filter to obtain a solid, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules;

[0090] A4. 1 g of nano carbon black and 3 g of polyethyleneimine were added to 55 mL of deionized water, placed in an ultrasonic field of 250 W and 40 kHz, and ultrasonically treated at 65 ° C for 10 h, filtered with a 0.22 μm polytetrafluoroethylene membrane, washed with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20 ° C to obtain modified nano carbon black;

[0091] A5. Add 3g of core-shell microcapsules to 35mL of Tris-HCl buffer with a pH of 9, stir evenly, add 0.4g of dopamine, stir and react for 2h, filter, wash with deionized water 3 times, 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 with deionized water 3 times, and dry at room temperature to obtain a composite demulsifier.

[0092] Comparative Example 1

[0093] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0094] S1. The pH of the kitchen oily wastewater was adjusted to 9 by using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 5 hours. The scum was collected by skimming to obtain pretreated oily wastewater a;

[0095] S2. 1000 mL of pretreated oily wastewater a was mixed with 50 g of composite demulsifier, air was introduced at 20 mm / s, and flotation treatment was performed for 55 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0097] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0098] The culture medium was sterilized at 105°C for 30 min, cooled to room temperature, and 1.5 × 10 9 CFU Bacillus XH-1 bacteria are added to 120 mL of sterilized culture medium, and cultured for 20 hours at a shaking speed of 180 rpm, a temperature of 35°C, and a pH of 9 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0100] A1. Add 6 g corn starch to 55 mL deionized water, stir at 80 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact with the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0101] A2. Add 3 g of cellulose to 35 mL of ethanol, stir evenly, add 1.4 g of sodium alginate and 0.8 g of calcium chloride, continue stirring for 20 min, add 1.4 g of starch-coated bacteria, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, vacuum filter to obtain a solid, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules;

[0102] A3. 1 g of nano carbon black and 3 g of polyethyleneimine were added to 55 mL of deionized water, placed in an ultrasonic field of 250 W and 40 kHz, and ultrasonically treated at 65 ° C for 10 h, filtered with a 0.22 μm polytetrafluoroethylene membrane, washed with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20 ° C to obtain modified nano carbon black;

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

[0104] Comparative Example 2

[0105] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0106] S1. The pH of the kitchen oily wastewater was adjusted to 9 using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a;

[0107] S2. 1000 mL of pretreated oily wastewater a was mixed with 50 g of composite demulsifier, air was introduced at 20 mm / s, and flotation treatment was performed for 55 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0109] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0110] The culture medium was sterilized at 105°C for 30 min, cooled to room temperature, and 1.5 × 10 9 CFU Bacillus XH-1 bacteria are added to 120 mL of sterilized culture medium, and cultured for 20 hours at a shaking speed of 180 rpm, a temperature of 35°C, and a pH of 9 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0112] A1. 45 g of 1-butyl-3-methylimidazole chloride and 1.6 g of cellulose were mixed and stirred at 85° C. until completely dissolved, 0.04 g of potassium persulfate, 0.4 g of methacryloyloxyethyl trimethylammonium chloride, 0.4 g of acrylamide and 0.5 g of 2-acrylamido-2-methyl-1-propane sulfonic acid were added, and the mixture was stirred at 80° C. for 3 h, cooled to room temperature, and soaked in 50 mL of ethanol for 4 h. The precipitate was collected by centrifugation at 2000 r / min, and the precipitate was dried in an oven at 50° C. for 10 min to obtain modified cellulose;

[0113] A2. Add 3 g of modified cellulose to 35 mL of ethanol, stir evenly, add 1.4 g of sodium alginate and 0.8 g of calcium chloride, continue stirring for 20 min, add 1.4 g of Bacillus XH-1 bacterial solution, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, vacuum filter to obtain a solid, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules;

[0114] A3. 1 g of nano carbon black and 3 g of polyethyleneimine were added to 55 mL of deionized water, placed in an ultrasonic field of 250 W and 40 kHz, and ultrasonically treated at 65 ° C for 10 h, filtered with a 0.22 μm polytetrafluoroethylene membrane, washed with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20 ° C to obtain modified nano carbon black;

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

[0116] Comparative Example 3

[0117] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0118] S1. The pH of the kitchen oily wastewater was adjusted to 9 using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a;

[0119] S2. 1000 mL of pretreated oily wastewater a was mixed with 50 g of composite demulsifier, air was introduced at 20 mm / s, and flotation treatment was performed for 55 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0121] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0122] The culture medium was sterilized at 105°C for 30 min, cooled to room temperature, and 1.5 × 10 9 CFU Bacillus XH-1 bacteria are added to 120 mL of sterilized culture medium, and cultured for 20 hours at a shaking speed of 180 rpm, a temperature of 35°C, and a pH of 9 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0124] A1. Add 6 g corn starch to 55 mL deionized water, stir at 80 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact with the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0125] A2. 1 g of nano carbon black and 3 g of polyethyleneimine were added to 55 mL of deionized water, placed in an ultrasonic field of 250 W and 40 kHz, and ultrasonically treated at 65 ° C for 10 h, filtered with a 0.22 μm polytetrafluoroethylene membrane, washed with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20 ° C to obtain modified nano carbon black;

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

[0127] Comparative Example 4

[0128] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0129] S1. The pH of the kitchen oily wastewater was adjusted to 9 using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a;

[0130] S2. 1000 mL of pretreated oily wastewater a was mixed with 50 g of core-shell microcapsules, air was introduced at 20 mm / s, and flotation treatment was performed for 55 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0132] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0133] The culture medium was sterilized at 105°C for 30 min, cooled to room temperature, and 1.5 × 10 9CFU Bacillus XH-1 bacteria are added to 120 mL of sterilized culture medium, and cultured for 20 hours at a shaking speed of 180 rpm, a temperature of 35°C, and a pH of 9 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0135] A1. Add 6 g corn starch to 55 mL deionized water, stir at 80 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact with the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0136] A2. 45 g of 1-butyl-3-methylimidazole chloride and 1.6 g of cellulose were mixed and stirred at 85° C. until completely dissolved, 0.04 g of potassium persulfate, 0.4 g of methacryloyloxyethyl trimethylammonium chloride, 0.4 g of acrylamide and 0.5 g of 2-acrylamido-2-methyl-1-propane sulfonic acid were added, and the mixture was stirred at 80° C. for 3 h, cooled to room temperature, and immersed in 50 mL of ethanol for 4 h. The precipitate was collected by centrifugation at 2000 r / min, and the precipitate was dried in an oven at 50° C. for 10 min to obtain modified cellulose;

[0137] A3. Add 3 g of modified cellulose to 35 mL of ethanol, stir evenly, add 1.4 g of sodium alginate and 0.8 g of calcium chloride, continue stirring for 20 min, add 1.4 g of starch-coated bacteria, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, obtain a solid by vacuum filtration, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules.

[0138] Comparative Example 5

[0139] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0140] S1. The pH of the kitchen oily wastewater was adjusted to 9 using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a;

[0141] S2. 1000 mL of pretreated oily wastewater a was mixed with 50 g of composite demulsifier, air was introduced at 20 mm / s, and flotation treatment was performed for 55 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0143] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0144] The culture medium was sterilized at 105°C for 30 min, cooled to room temperature, and 1.5 × 10 9 CFU Bacillus XH-1 bacteria are added to 120 mL of sterilized culture medium, and cultured for 20 hours at a shaking speed of 180 rpm, a temperature of 35°C, and a pH of 9 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0146] A1. Add 6 g corn starch to 55 mL deionized water, stir at 80 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact with the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0147] A2. 45 g of 1-butyl-3-methylimidazole chloride and 1.6 g of cellulose were mixed and stirred at 85° C. until completely dissolved, 0.04 g of potassium persulfate, 0.4 g of methacryloyloxyethyl trimethylammonium chloride, 0.4 g of acrylamide and 0.5 g of 2-acrylamido-2-methyl-1-propane sulfonic acid were added, and the mixture was stirred at 80° C. for 3 h, cooled to room temperature, and immersed in 50 mL of ethanol for 4 h. The precipitate was collected by centrifugation at 2000 r / min, and the precipitate was dried in an oven at 50° C. for 10 min to obtain modified cellulose;

[0148] A3. Add 3 g of modified cellulose to 35 mL of ethanol, stir evenly, add 1.4 g of sodium alginate and 0.8 g of calcium chloride, continue stirring for 20 min, add 1.4 g of starch-coated bacteria, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, vacuum filter to obtain a solid, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules;

[0149] A4. 1 g of nano carbon black and 3 g of polyethyleneimine were added to 55 mL of deionized water, placed in an ultrasonic field of 250 W and 40 kHz, and ultrasonically treated at 65 ° C for 10 h, filtered with a 0.22 μm polytetrafluoroethylene membrane, washed with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20 ° C to obtain modified nano carbon black;

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

[0151] Comparative Example 6

[0152] A process for treating oily kitchen wastewater based on demulsifiers comprises the following steps:

[0153] S1. The pH of the kitchen oily wastewater was adjusted to 9 using a sodium hydroxide solution having a concentration of 1 mol / L, and then allowed to settle for 5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a;

[0154] S2. 1000 mL of pretreated oily wastewater a was mixed with 50 g of dopamine-modified core-shell microcapsules, air was introduced at 20 mm / s, and flotation treatment was performed for 55 min. The suspended matter was skimmed and collected to obtain pretreated oily wastewater b;

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

[0156] Bacillus XH-1 bacterial solution is prepared by the following steps:

[0157] The culture medium was sterilized at 105°C for 30 min, cooled to room temperature, and 1.5 × 10 9 CFU Bacillus XH-1 bacteria are added to 120 mL of sterilized culture medium, and cultured for 20 hours at a shaking speed of 180 rpm, a temperature of 35°C, and a pH of 9 to obtain a Bacillus XH-1 bacterial liquid; wherein the culture medium is mixed with wheat bran, bean cake powder, 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 composite demulsifier is specifically prepared by the following steps:

[0159] A1. Add 6 g corn starch to 55 mL deionized water, stir at 80 ° C until the starch is completely gelatinized, cool to room temperature, add 5 mL of Bacillus XH-1 bacterial solution, stir for 30 minutes to allow the bacteria to fully contact with the starch, and dry at room temperature overnight to obtain starch-coated bacteria;

[0160] A2. 45 g of 1-butyl-3-methylimidazole chloride and 1.6 g of cellulose were mixed and stirred at 85° C. until completely dissolved, 0.04 g of potassium persulfate, 0.4 g of methacryloyloxyethyl trimethylammonium chloride, 0.4 g of acrylamide and 0.5 g of 2-acrylamido-2-methyl-1-propane sulfonic acid were added, and the mixture was stirred at 80° C. for 3 h, cooled to room temperature, and immersed in 50 mL of ethanol for 4 h. The precipitate was collected by centrifugation at 2000 r / min, and the precipitate was dried in an oven at 50° C. for 10 min to obtain modified cellulose;

[0161] A3. Add 3 g of modified cellulose to 35 mL of ethanol, stir evenly, add 1.4 g of sodium alginate and 0.8 g of calcium chloride, continue stirring for 20 min, add 1.4 g of starch-coated bacteria, ultrasonically treat at 120 W and 25 ° C for 1.5 h to eliminate bubbles, vacuum filter to obtain a solid, and dry the solid at 30 ° C for 2 h to obtain core-shell microcapsules;

[0162] A4. 1 g of nano carbon black and 3 g of polyethyleneimine were added to 55 mL of deionized water, placed in an ultrasonic field of 250 W and 40 kHz, and ultrasonically treated at 65 ° C for 10 h, filtered with a 0.22 μm polytetrafluoroethylene membrane, washed with deionized water 5 times to remove unreacted polyethyleneimine, and freeze-dried at -20 ° C to obtain modified nano carbon black;

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

[0164] Now, various indicators of the kitchen oily wastewater treated in Examples 1-3 and Comparative Examples 1-6 are tested.

[0165] The indicators of the oily kitchen wastewater used in Examples 1-3 and Comparative Examples 1-6 of the present invention are as follows: chemical oxygen demand (COD) is 93 g / L, oil is 15.5 g / L, ammonium nitrogen (NH 4 + -N) was 345 mg / L, total nitrogen (TN) was 1950 mg / L, total phosphorus (TP) was 84.5 mg / L, and pH was 4.

[0166] Determine the nitrogen and phosphorus content in the filtrate of step S3: The filtrate in step S3 is measured by Nessler's reagent spectrophotometer method and ascorbic acid method respectively, and the NH 4 + -N and TN concentrations.

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

[0168] Determination of the content of grease and chemical oxygen demand in the filtrate of step S3: The chemical oxygen demand and grease content were tested using the National Environmental Protection Administration's "Water and Wastewater Monitoring and Analysis Methods" Editorial Committee. Water and Wastewater Monitoring and Analysis Methods [M]. 4th edition. As shown in Table 1 below.

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

[0170]

[0171] It can be seen from the data in Table 1 that the various indicators of the kitchen oily wastewater treated in Examples 1-3 all meet the A-level standard in GB / T31962 "Water Quality Standard for Sewage 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 kitchen wastewater. The removal effect of nitrogen and phosphorus in the filtrate decreased, which proved that the introduction of quaternary ammonium, amide and sulfonic acid active adsorption functional groups on the cellulose molecular chain can adsorb nitrogen and phosphorus elements in the oily kitchen wastewater, complete the removal of nitrogen and phosphorus elements in the oily kitchen wastewater, and make the oily kitchen wastewater meet the releasable standard.

[0173] In Comparative Example 2, the composite demulsifier prepared by replacing the starch-coated bacteria with Bacillus XH-1 bacterial liquid was used for the treatment of oily wastewater from restaurant kitchens, and the treatment effect decreased. This proves that corn starch-coated Bacillus XH-1 bacterial liquid can improve the stability of Bacillus XH-1 bacterial liquid in oily wastewater from restaurant kitchens, and avoid Bacillus XH-1 bacteria being easily affected by pH and temperature in oily wastewater, which leads to the failure of the demulsifier.

[0174] In Comparative Example 3, the core-shell microcapsules were replaced with a composite demulsifier prepared by starch-coated bacteria and used for the treatment of oily wastewater from restaurant kitchens. The treatment effect was reduced, indicating that the modified cellulose, sodium alginate and calcium chloride were mixed as wall materials and starch-coated bacteria were used as core materials to prepare core-shell microcapsules, which further improved the stability of starch-coated bacteria in oily wastewater from restaurant kitchens and improved the treatment efficiency of oily wastewater from restaurant kitchens.

[0175] In Comparative Example 4, the composite demulsifier was replaced with core-shell microcapsules for the treatment of oily kitchen wastewater, and the treatment effect decreased, proving that the modified nano-carbon black can replace the interfacial film on the surface of the water-in-oil emulsion, causing the oil droplets to aggregate and precipitate, and has a synergistic effect with the Bacillus XH-1 bacteria in terms of demulsification performance, thereby improving the demulsification efficiency. In addition, the modified nano-carbon black can be electrostatically bonded with the modified carboxymethyl cellulose, so that the adsorbed modified carboxymethyl cellulose flocculates and settles along with the modified nano-carbon black, and is removed by filtration.

[0176] In Comparative Example 5, the composite demulsifier prepared by replacing the dopamine-modified core-shell microcapsules with core-shell microcapsules was used for the treatment of oily kitchen wastewater, and the treatment effect was reduced, indicating that the dopamine-modified core-shell microcapsules enabled the core-shell microcapsules to combine with the modified nano-carbon black through chemical bonds to form a composite demulsifier, thereby increasing the treatment effect.

[0177] In Comparative Example 6, the composite demulsifier was replaced with dopamine-modified core-shell microcapsules for the treatment of oily kitchen wastewater, and 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 interface film of the water-in-oil emulsion through π-π interaction, so that the composite demulsifier adheres to the surface of the water-in-oil emulsion, completes the demulsification, causes a large number of oil droplets to gather, and completes the removal of grease.

[0178] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0179] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A process for treating oily kitchen wastewater based on demulsifiers, characterized in that: The following steps are involved: S1. After adjusting the pH of the kitchen oily wastewater to 6-9, the wastewater was allowed to settle for 2-5 hours, and the scum was collected by skimming to obtain pretreated oily wastewater a; S2. The pretreated oily wastewater a is mixed with a composite demulsifier, air is introduced at 10-20 mm / s, and flotation treatment is performed for 45-55 min, and the suspended matter is skimmed and collected to obtain pretreated oily wastewater b; S3. The pretreated oily wastewater b is filtered, the filtrate and the precipitate are collected, and the filtrate is recovered for testing and 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 mixing modified cellulose, sodium alginate and calcium chloride as wall materials and starch-coated bacteria as core materials; The modified cellulose is obtained by mixed reaction of cellulose, methacryloyloxyethyltrimethylammonium chloride, acrylamide and 2-acrylamide-2-methyl-1-propane sulfonic acid.

2. The process for treating oily kitchen wastewater based on demulsifier according to claim 1, characterized in that: The composite demulsifier is prepared by the following steps: A1. Add corn starch to deionized water, stir at 75-85°C 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 bacteria; A2. 1-butyl-3-methylimidazole chloride and cellulose are mixed, stirred and dissolved at 75-85° C., potassium persulfate, methacryloyloxyethyl trimethylammonium chloride, acrylamide and 2-acrylamido-2-methyl-1-propane sulfonic acid are added, and after the reaction is completed, the mixture is cooled to room temperature, soaked in ethanol, centrifuged and dried to obtain modified cellulose; A3. The modified cellulose was added to ethanol, stirred evenly, sodium alginate and calcium chloride were added, stirred evenly, starch-coated bacteria were added, and after ultrasonic treatment, a solid was obtained by vacuum filtration. After the solid was dried, core-shell microcapsules were obtained; A4. Add nano carbon black and polyethyleneimine to deionized water, place in an ultrasonic field, and ultrasonically treat at 55-65°C for 6-10h, filter, wash, and freeze-dry to obtain modified nano carbon black; A5. The core-shell microcapsules were added to a Tris-HCl buffer having a pH of 8-9, stirred evenly, and dopamine was added. After the reaction was completed, the dopamine-modified core-shell microcapsules were filtered, washed, and dried to obtain dopamine-modified core-shell microcapsules; Dopamine modified core-shell microcapsules and modified nano carbon black are added into ethanol, stirred evenly, filtered, washed and dried to obtain a composite demulsifier.

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

4. The process for treating oily kitchen wastewater based on demulsifier according to claim 3, characterized in that: The culture medium is prepared by mixing wheat bran, bean cake powder, waste frying 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 kitchen wastewater based on demulsifier according to claim 2, characterized in that: In step A2, the mass ratio of 1-butyl-3-methylimidazole chloride, cellulose, potassium persulfate, methacryloyloxyethyltrimethylammonium chloride, acrylamide, and 2-acrylamido-2-methyl-1-propane sulfonic 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 demulsifier according to claim 2, characterized in that: In step A3, the dosage ratio of the 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 kitchen wastewater based on demulsifier according to claim 2, characterized in that: In step A4, the ratio of the nano carbon black, polyethyleneimine and deionized water is (0.6-1) g: (2-3) g: (45-55) mL.

8. The process for treating oily kitchen wastewater based on demulsifier 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 dopamine modified core-shell microcapsules, modified nano carbon black, and ethanol are used in a ratio of (2-3) g: (1-1.4) g: (45-55) mL.

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