AO-MBR membrane integrated sewage treatment device suitable for transformer substation and sewage treatment method

Abstract

The invention discloses an AO-MBR membrane integrated sewage treatment device suitable for a transformer substation and a sewage treatment method, and aims to solve the problem of pollution of oil leakage of a transformer to a water body in the environment. A water inlet tank, an air floatation adjusting tank, a photocatalytic reaction tank, an A-stage anoxic tank, an O-stage aerobic tank, an MBR membrane tank and a water outlet tank are sequentially arranged in the integrated water treatment device in the water flow direction, a chitosan-TiO2 composite photocatalyst is added into the photocatalytic reaction tank, net cages are arranged in the A-stage anoxic tank and the O-stage aerobic tank, the net cages are filled with artificial carriers, and the artificial carriers are arranged in the MBR membrane tank. A membrane component is arranged in the MBR membrane tank, anaerobic activated sludge is inoculated in the MBR membrane tank, and a disinfectant is added into the water outlet tank. According to the integrated water treatment device, an A / O + MBR membrane + disinfection process is adopted, and meanwhile, the physical and chemical treatment mode of the front air floatation regulating tank and the photocatalytic reaction tank is adopted, so that the removal rate of COD can reach 95% or above, and the removal rate of organic insulating oil pollutants can reach 99%.

Description

Technical Field

[0001] The invention relates to an A / O-MBR membrane sewage treatment device and a sewage treatment method using the device. Background Art

[0002] Oil-immersed transformers are commonly used power supply equipment. The insulating oil in the transformer plays two main roles: one is insulation, which requires the insulating oil to have a high breakdown voltage and volume resistivity, and the other is cooling. During the long service life of the transformer, affected by factors such as maintenance quality, equipment technology and operating environment, the transformer often leaks oil to varying degrees. Transformers with oil leakage will not only pollute the on-site environment, but also pollute nearby soil and water sources, reduce their service life, and in severe cases endanger the safe and reliable operation of the equipment and even the power grid.

[0003] Transformer insulating oil is a mixture of different hydrocarbons, usually composed of three main components: alkanes, cycloalkanes and aromatics. Alkanes include saturated straight-chain (normal) and branched (iso) alkanes. Cycloalkanes are the most common hydrocarbons in transformer oil. The main components of the aromatic part of transformer oil are monoaromatic hydrocarbons substituted by alkyl and cycloalkyl groups. Leaking transformer insulating oil is easily mixed with municipal wastewater. After the insulating oil enters the water body, it is difficult to biodegrade. In addition, municipal wastewater contains pollutants such as ammonia nitrogen. There are few existing water treatment processes for transformer insulating oil. Therefore, it is urgent to develop a treatment process for water pollution caused by leaking transformer insulating oil. Summary of the invention

[0004] The present invention aims to solve the problem of oil leakage from transformer causing pollution to water bodies in the environment, and provides an AO-MBR membrane integrated sewage treatment device and a sewage treatment method suitable for a transformer substation.

[0005] The AO-MBR membrane integrated sewage treatment device applicable to a substation of the present invention comprises an inlet pool, an air flotation regulating pool, a photocatalytic reaction pool, an A-level anoxic pool, an O-level aerobic pool, an MBR membrane pool and an outlet pool. The inlet pool, the air flotation regulating pool, the photocatalytic reaction pool, the A-level anoxic pool, the O-level aerobic pool, the MBR membrane pool and the outlet pool are sequentially arranged in a box body along the water flow direction, and adjacent pool bodies are separated by partitions;

[0006] A micro-nano bubble generator is arranged at the bottom of the flotation adjustment tank, an ultraviolet light source is arranged in the photocatalytic reaction tank, and a chitosan-TiO2 composite photocatalyst is added, a mesh cage is arranged in the A-level anoxic tank and the O-level aerobic tank, and the mesh cage is filled with artificial carriers, an aeration plate is arranged at the bottom of the O-level aerobic tank, a membrane assembly is arranged in the MBR membrane tank, anaerobic activated sludge is inoculated in the MBR membrane tank, and a disinfectant is added to the effluent tank;

[0007] A nitrification liquid reflux port is provided on the Class O aerobic tank, and the nitrification liquid reflux port is connected to the liquid inlet of the Class A anoxic tank through a nitrification liquid reflux pipe. A sludge reflux port is provided at the bottom of the MBR membrane tank, and a sludge inlet is provided at the bottom of the Class A anoxic tank. One end of the sludge reflux pipe is connected to the sludge reflux port, and the other end of the sludge reflux pipe is connected to the sludge inlet of the Class A anoxic tank.

[0008] The preparation method of chitosan-TiO2 composite photocatalyst is as follows:

[0009] 1. Add TiO2 powder and melamine into deionized water, stir evenly, filter and collect filter cake, dry the filter cake and grind it to obtain mixed powder, calcine the mixed powder at 500-600° C. in nitrogen atmosphere, wash and dry to obtain TiO2 / g-C3N4 composite material;

[0010] 2. adding chitosan powder to 1 wt% to 4 wt% glacial acetic acid solution to obtain a chitosan solution, wherein the concentration of chitosan in the chitosan solution is 1 wt% to 4 wt%;

[0011] 3. Adding the TiO2 / g-C3N4 composite material and cellulose into deionized water, uniformly dispersing by ultrasonication, and obtaining a suspension;

[0012] 4. The chitosan solution and the suspension are mixed and stirred evenly, glutaraldehyde solution is added dropwise, and the reaction is carried out at 50-60° C. for 1-1.5 hours to obtain a cross-linked reaction product, the cross-linked reaction product is frozen at low temperature and then freeze-dried, and the cold trap temperature is controlled at -40° C. to -50° C. to obtain a chitosan-TiO2 composite photocatalyst.

[0013] The method of the present invention using the AO-MBR membrane integrated sewage treatment device suitable for a substation to treat sewage is as follows:

[0014] 1. The wastewater containing transformer insulating oil is introduced into the AO-MBR membrane integrated wastewater treatment device suitable for substations. The wastewater containing transformer insulating oil passes through the water inlet tank, the air flotation adjustment tank and the photocatalytic reaction tank in sequence. The ultraviolet light source is turned on in the photocatalytic reaction tank, and the chitosan-TiO2 composite photocatalyst is added to carry out photocatalytic reaction;

[0015] 2. The effluent from the photocatalytic reaction pool flows through the A-class anoxic pool and the O-class aerobic pool in sequence. In the O-class aerobic pool, a nitrification reaction is carried out by aerobic microorganisms. The sewage in the O-class aerobic pool flows back to the A-class anoxic pool through the nitrification liquid return pipe for denitrification. The hydraulic retention time of the A-class anoxic pool is controlled to be 2 to 5 hours, and the hydraulic retention time of the O-class aerobic pool is controlled to be 4 to 8 hours. The effluent from the O-class aerobic pool flows into the MBR membrane pool and is denitrified by anaerobic activated sludge.

[0016] 3. The effluent from the MBR membrane pool flows into the effluent pool for disinfection. After disinfection, the purified water is discharged to complete the treatment of wastewater containing transformer insulating oil.

[0017] The AO-MBR membrane integrated sewage treatment device suitable for a substation mainly comprises a photocatalytic reaction tank, an A-level anoxic tank, an O-level aerobic tank and an MBR membrane tank. A chitosan-TiO2 composite photocatalyst is added into the photocatalytic reaction tank. The chitosan-TiO2 composite photocatalyst pre-absorbs and degrades insulating oil in sewage, thereby improving the later biodegradability of the insulating oil. The AO-MBR membrane integrated sewage treatment device suitable for a substation of the present invention combines an A / O bioreactor and an MBR membrane bioreactor. The O-level aerobic tank in the A / O bioreactor performs nitrification reaction to convert ammonia nitrogen into nitrate nitrogen. The nitrified liquid of the O-level aerobic tank flows back to the anoxic tank to provide organic carbon as an electron acceptor. Denitrification reaction is performed in the A-level anoxic tank to remove nitrogen. The A / O bioreactor can effectively remove pollutants such as BOD, ammonia nitrogen and phosphorus in municipal sewage. The effluent of the A / O bioreactor enters the MBR membrane bioreactor. The MBR membrane bioreactor is an anaerobic environment. The membrane assembly allows anaerobic microorganisms to be trapped in the reactor. The concentration of anaerobic microorganisms is high, and the removal effect of organic pollutants and COD is better. In addition, the sludge in the MBR membrane bioreactor can also flow back to the A-level anoxic tank to ensure the sludge concentration of the biochemical system (that is, to ensure the total amount of biochemical microorganisms).

[0018] The AO-MBR membrane integrated sewage treatment device and sewage treatment method applicable to a transformer substation adopt an A / O+MBR membrane+sodium hypochlorite disinfection process, and simultaneously a pre-placed air flotation regulating tank and a photocatalytic reaction tank are used for physicochemical treatment. The photocatalytic reaction tank can pre-degrade transformer insulating oil and improve the biochemical property of organic oil pollutants. The A / O+MBR membrane process is combined in the later stage to improve the removal effect of COD, BOD and ammonia nitrogen. The AO-MBR membrane integrated sewage treatment device applicable to a transformer substation is used to treat sewage containing transformer insulating oil, and the removal rates of COD and ammonia nitrogen can reach about 95%, and the removal rate of organic insulating oil pollutants can reach 99%. The treated sewage quality can reach the Class A standard of Pollutant Discharge Standard for Urban Sewage Treatment Plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the AO-MBR membrane integrated sewage treatment device applicable to a substation of the present invention;

[0020] Figure 2 This is a real photo of the AO-MBR membrane integrated sewage treatment device suitable for a substation according to the present invention. DETAILED DESCRIPTION

[0021] Specific implementation method 1: This implementation method is applicable to the AO-MBR membrane integrated sewage treatment device of the substation, which includes an inlet pool 1, an air flotation regulating pool 2, a photocatalytic reaction pool 3, an A-level anoxic pool 4, an O-level aerobic pool 5, an MBR membrane pool 6 and an outlet pool 7. The inlet pool 1, the air flotation regulating pool 2, the photocatalytic reaction pool 3, the A-level anoxic pool 4, the O-level aerobic pool 5, the MBR membrane pool 6 and the outlet pool 7 are sequentially arranged in the box body along the water flow direction, and adjacent pool bodies are separated by partitions;

[0022] A micro-nano bubble generator 8 is arranged at the bottom of the flotation adjustment tank 2, an ultraviolet light source 9 is arranged in the photocatalytic reaction tank 3, and a chitosan-TiO2 composite photocatalyst is added, and a mesh cage is arranged in the A-level anoxic tank 4 and the O-level aerobic tank 5, respectively, and the mesh cage is filled with an artificial carrier, and an aeration plate 10 is arranged at the bottom of the O-level aerobic tank 5, and a membrane assembly 11 is arranged in the MBR membrane tank 6, and anaerobic activated sludge is inoculated in the MBR membrane tank 6, and a disinfectant is added to the effluent tank 7;

[0023] A nitrification liquid reflux port is provided on the O-class aerobic tank 5, and the nitrification liquid reflux port is connected to the liquid inlet of the A-class anoxic tank 4 through a nitrification liquid reflux pipe 13. A sludge reflux port is provided at the bottom of the MBR membrane tank 6, and a sludge inlet is provided at the bottom of the A-class anoxic tank 4. One end of the sludge reflux pipe 12 is connected to the sludge reflux port, and the other end of the sludge reflux pipe 12 is connected to the sludge inlet of the A-class anoxic tank 4.

[0024] The preparation method of chitosan-TiO2 composite photocatalyst is as follows:

[0025] 1. Add TiO2 powder and melamine into deionized water, stir evenly, filter and collect filter cake, dry the filter cake and grind it to obtain mixed powder, calcine the mixed powder at 500-600° C. in nitrogen atmosphere, wash and dry to obtain TiO2 / g-C3N4 composite material;

[0026] 2. adding chitosan powder to 1 wt% to 4 wt% glacial acetic acid solution to obtain a chitosan solution, wherein the concentration of chitosan in the chitosan solution is 1 wt% to 4 wt%;

[0027] 3. Adding the TiO2 / g-C3N4 composite material and cellulose into deionized water, uniformly dispersing by ultrasonication, and obtaining a suspension;

[0028] 4. The chitosan solution and the suspension are mixed and stirred evenly, glutaraldehyde solution is added dropwise, and the reaction is carried out at 50-60° C. for 1-1.5 hours to obtain a cross-linked reaction product, the cross-linked reaction product is frozen at low temperature and then freeze-dried, and the cold trap temperature is controlled at -40° C. to -50° C. to obtain a chitosan-TiO2 composite photocatalyst.

[0029] The chitosan-TiO2 composite photocatalyst of this embodiment is composed of TiO2 / g-C3N4 photocatalytic material, cellulose and chitosan. The TiO2 / g-C3N4 photocatalytic material, TiO2 and g-C3N4 form a heterojunction to inhibit the recombination of photogenerated electrons and holes. Under ultraviolet light irradiation, the chitosan-TiO2 composite photocatalyst generates ·OH and ·O 2- Active free radicals such as chitosan and cellulose open the ring of petroleum organic pollutants or convert them into intermediate products, thereby improving the biodegradability of organic pollutants. At the same time, chitosan and cellulose have specific adsorption effects on petroleum organic pollutants and have good biological properties. The adsorption of chitosan and cellulose can quickly remove the transformer insulating oil components in sewage, reducing the inhibitory effect of transformer insulating oil on subsequent biological treatment. Chitosan is freeze-dried to form a porous structure, which increases the specific surface area of ​​the composite material and improves the treatment efficiency of sewage containing transformer insulating oil.

[0030] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that a grille is provided in the water inlet pool 1 .

[0031] This embodiment pre-treats the sewage by intercepting it with a grid, thereby preliminarily reducing the content of inorganic particulate matter.

[0032] Specific embodiment three: This embodiment is different from specific embodiment one or two in that the aeration plate 10 is connected to the air pump 16 through a gas pipeline.

[0033] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the disinfectant added into the outlet pool 7 is sodium hypochlorite.

[0034] Specific implementation mode 5: This implementation mode is different from specific implementation modes 1 to 4 in that a mud discharge port is further opened at the bottom of the MBR membrane pool 6 .

[0035] Specific embodiment six: This embodiment is different from specific embodiments one to five in that a cover plate 14 is provided on the top of the water inlet tank 1, the flotation adjustment tank 2, the photocatalytic reaction tank 3, the Class A anoxic tank 4, the Class O aerobic tank 5, the MBR membrane tank 6 and the water outlet tank 7.

[0036] Specific implementation method seven: This implementation method uses the AO-MBR membrane integrated sewage treatment device suitable for substations to treat sewage as follows:

[0037] 1. The sewage containing transformer insulating oil is introduced into the AO-MBR membrane integrated sewage treatment device suitable for the substation. The sewage containing transformer insulating oil passes through the water inlet tank 1, the air flotation adjustment tank 2 and the photocatalytic reaction tank 3 in sequence. The ultraviolet light source 9 is turned on in the photocatalytic reaction tank 3, and the chitosan-TiO2 composite photocatalyst is added to carry out the photocatalytic reaction;

[0038] 2. The effluent of the photocatalytic reaction pool 3 flows through the A-class anoxic pool 4 and the O-class aerobic pool 5 in sequence, and a nitrification reaction is carried out in the O-class aerobic pool 5 by using aerobic microorganisms. The sewage in the O-class aerobic pool 5 flows back to the A-class anoxic pool 4 through the nitrification liquid return pipe 13 for denitrification. The hydraulic retention time of the A-class anoxic pool 4 is controlled to be 2 to 5 hours, and the hydraulic retention time of the O-class aerobic pool 5 is controlled to be 4 to 8 hours. The effluent of the O-class aerobic pool 5 flows into the MBR membrane pool 6 and is denitrified by anaerobic activated sludge.

[0039] 3. The effluent from the MBR membrane pool 6 flows into the effluent pool 7 for disinfection, and the purified water is discharged after disinfection, thereby completing the treatment of the wastewater containing transformer insulating oil.

[0040] The flotation adjustment tank of this embodiment can be used to adjust the pH of wastewater containing transformer insulating oil to 6-8.

[0041] In step 1 of this embodiment, the dosage of the chitosan-TiO2 composite photocatalyst is controlled to be 0.1-4 g / L.

[0042] Specific embodiment eight: The difference between this embodiment and specific embodiment seven is that in step one, when the content of transformer insulating oil in the wastewater containing transformer insulating oil is higher than 40 mg / L, the micro-nano bubble generator 8 in the flotation adjustment tank 2 is turned on.

[0043] In this embodiment, when the content of transformer insulating oil in the wastewater containing transformer insulating oil is low, the micro-nano bubble generator may not be turned on.

[0044] Specific embodiment 9: The difference between this embodiment and specific embodiment 7 or 8 is that in step 2, the hydraulic retention time of the A-level anoxic pool 4 is controlled to be 3 to 5 hours, and the hydraulic retention time of the O-level aerobic pool 5 is controlled to be 4 to 6 hours.

[0045] Specific embodiment 10: This embodiment is different from any one of specific embodiments 7 to 9 in that the hydraulic retention time of the MBR membrane pool 6 in step 2 is controlled to be 8 to 14 hours.

[0046] Embodiment 1: This embodiment is applicable to the AO-MBR membrane integrated sewage treatment device of the substation, including an inlet pool 1, an air flotation regulating pool 2, a photocatalytic reaction pool 3, an A-level anoxic pool 4, an O-level aerobic pool 5, an MBR membrane pool 6 and an outlet pool 7. The inlet pool 1, the air flotation regulating pool 2, the photocatalytic reaction pool 3, the A-level anoxic pool 4, the O-level aerobic pool 5, the MBR membrane pool 6 and the outlet pool 7 are sequentially arranged in the box body along the water flow direction, and the adjacent pool bodies are separated by partitions. A cover plate 14 is arranged on the top of the inlet pool 1, the air flotation regulating pool 2, the photocatalytic reaction pool 3, the A-level anoxic pool 4, the O-level aerobic pool 5, the MBR membrane pool 6 and the outlet pool 7;

[0047] A grid is arranged in the water inlet pool 1, and the lower part of the water inlet pool 1 is an electrical cabinet 15, which is mainly used to power the ultraviolet light source 9 and the air pump 16. A micro-nano bubble generator 8 is arranged at the bottom of the air flotation adjustment pool 2, and an ultraviolet light source 9 is arranged in the photocatalytic reaction pool 3. The outer cover of the ultraviolet light source 9 is provided with a glass cover. Chitosan-TiO2 composite photocatalyst is added into the photocatalytic reaction pool 3 and stirred by a stirrer for reaction. A grid is arranged in the A-level anoxic pool 4 and the O-level aerobic pool 5 respectively. The cage is filled with artificial carriers, the artificial carriers in the A-level anoxic tank 4 are loaded with anaerobic biofilms, the artificial carriers in the O-level aerobic tank 5 are loaded with aerobic biofilms, an aeration plate 10 is arranged at the bottom of the O-level aerobic tank 5, the aeration plate 10 is connected to the air pump 16 through a gas pipeline, a membrane assembly 11 is arranged in the MBR membrane tank 6, the MBR membrane tank 6 is inoculated with anaerobic activated sludge, and sodium hypochlorite disinfectant is added to the effluent tank 7, and the sodium hypochlorite disinfectant is installed in the medicine box;

[0048] A nitrification liquid reflux port is provided on the O-class aerobic tank 5, and the nitrification liquid reflux port is connected to the liquid inlet of the A-class anoxic tank 4 through a nitrification liquid reflux pipe 13. A sludge reflux port is provided at the bottom of the MBR membrane tank 6, and a sludge inlet is provided at the bottom of the A-class anoxic tank 4. One end of the sludge reflux pipe 12 is connected to the sludge reflux port, and the other end of the sludge reflux pipe 12 is connected to the sludge inlet of the A-class anoxic tank 4. A sludge reflux pump is provided on the sludge reflux pipe 12.

[0049] The preparation method of chitosan-TiO2 composite photocatalyst is as follows:

[0050] 1. Add TiO2 powder and melamine in a mass ratio of 4:1 into deionized water, stir evenly, filter and collect filter cake, dry the filter cake and grind it to obtain a mixed powder, calcine the mixed powder at 600°C for 2h under a nitrogen atmosphere, and obtain a TiO2 / g-C3N4 composite material after washing and drying;

[0051] 2. adding chitosan powder into a 2 wt % glacial acetic acid solution to obtain a chitosan solution, wherein the concentration of chitosan in the chitosan solution is 2 wt %;

[0052] 3. Add TiO2 / g-C3N4 composite material and cellulose into deionized water at a mass ratio of 5:1, and disperse them uniformly by ultrasonication to obtain a suspension;

[0053] Fourth, the chitosan solution and the suspension were mixed and stirred evenly, glutaraldehyde solution was added dropwise, the volume content of glutaraldehyde was one eighth of the mixed solution of the chitosan solution and the suspension, and the reaction was carried out at 50°C for 1 hour to obtain a cross-linked product, and the cross-linked product was frozen at -20°C and then freeze-dried, and the cold trap temperature was controlled to -50°C to obtain a chitosan-TiO2 composite photocatalyst;

[0054] In step 4, the mass ratio of chitosan in the chitosan solution to the TiO2 / g-C3N4 composite material in the suspension is 8:1.5.

[0055] Application Example 1: This embodiment uses the AO-MBR membrane integrated sewage treatment device for substations described in Example 1 to perform sewage treatment as follows:

[0056] 1. The sewage containing transformer insulating oil is passed into the AO-MBR membrane integrated sewage treatment device suitable for the substation. The sewage containing transformer insulating oil passes through the water inlet tank 1, the air flotation regulating tank 2 and the photocatalytic reaction tank 3 in sequence. The micro-nano bubble generator 8 in the air flotation regulating tank 2 is not turned on. The ultraviolet light source 9 is turned on in the photocatalytic reaction tank 3 to carry out the photocatalytic reaction for 20 minutes. The dosage of the chitosan-TiO2 composite photocatalyst is 0.5 g / L.

[0057] 2. The effluent of the photocatalytic reaction pool 3 flows through the A-class anoxic pool 4 and the O-class aerobic pool 5 in sequence. A nitrification reaction is carried out in the O-class aerobic pool 5 by using aerobic microorganisms. The sewage in the O-class aerobic pool 5 flows back to the A-class anoxic pool 4 through the nitrification liquid return pipe 13 for denitrification. The hydraulic retention time of the A-class anoxic pool 4 is controlled to be 3 hours, and the hydraulic retention time of the O-class aerobic pool 5 is controlled to be 4 hours. The effluent of the O-class aerobic pool 5 flows into the MBR membrane pool 6. The concentration of the anaerobic activated sludge in the MBR membrane pool 6 is 3500 mg / L. The hydraulic retention time of the MBR membrane pool 6 is controlled to be 8 hours, and denitrification is carried out by the anaerobic activated sludge.

[0058] 3. The effluent from the MBR membrane pool 6 flows into the effluent pool 7 for disinfection, and the purified water is discharged after disinfection, thereby completing the treatment of the wastewater containing transformer insulating oil.

[0059] The COD content of the sewage containing transformer insulating oil in this embodiment is 65.8 mg / L, the BOD content is 25.6 mg / L, the SS content is 16.6 mg / L, the petroleum hydrocarbon pollutants (including alkanes, cycloalkanes and aromatics) content is 22.2 mg / L, the ammonia nitrogen content is 24.1 mg / L, and the total phosphorus content is 7.3 mg / L. After being treated by this application embodiment, the COD content in the effluent of the effluent pool 7 is 1.53 mg / L, the BOD content is 2.85 mg / L, the SS content is 3.19 mg / L, the petroleum pollutants (including alkanes, cycloalkanes and aromatics) content is 0.065 mg / L, the ammonia nitrogen content is 0.077 mg / L, and the total phosphorus content is 0.1 mg / L. The treated sewage water quality meets the Class A standard of "Pollutant Discharge Standard for Urban Sewage Treatment Plants" GB18918-2002.

[0060] Application Example 2: This embodiment uses the AO-MBR membrane integrated sewage treatment device for substations described in Example 1 to perform sewage treatment as follows:

[0061] 1. The sewage containing transformer insulating oil is introduced into the AO-MBR membrane integrated sewage treatment device suitable for the substation. The sewage containing transformer insulating oil passes through the water inlet tank 1, the air flotation regulating tank 2 and the photocatalytic reaction tank 3 in sequence. The micro-nano bubble generator 8 in the air flotation regulating tank 2 is turned on to generate micro-nano bubbles. The ultraviolet light source 9 is turned on in the photocatalytic reaction tank 3 to carry out photocatalytic reaction for 20 minutes. The dosage of the chitosan-TiO2 composite photocatalyst is 1.0 g / L.

[0062] 2. The effluent of the photocatalytic reaction pool 3 flows through the A-class anoxic pool 4 and the O-class aerobic pool 5 in sequence. A nitrification reaction is carried out in the O-class aerobic pool 5 by using aerobic microorganisms. The sewage in the O-class aerobic pool 5 flows back to the A-class anoxic pool 4 through the nitrification liquid return pipe 13 for denitrification. The hydraulic retention time of the A-class anoxic pool 4 is controlled to be 4 hours, and the hydraulic retention time of the O-class aerobic pool 5 is controlled to be 6 hours. The effluent of the O-class aerobic pool 5 flows into the MBR membrane pool 6. The concentration of the anaerobic activated sludge in the MBR membrane pool 6 is 3500 mg / L. The hydraulic retention time of the MBR membrane pool 6 is controlled to be 10 hours, and denitrification is carried out by the anaerobic activated sludge.

[0063] 3. The effluent from the MBR membrane pool 6 flows into the effluent pool 7 for disinfection, and the purified water is discharged after disinfection, thereby completing the treatment of the wastewater containing transformer insulating oil.

[0064] The COD content of the sewage containing transformer insulating oil in this embodiment is 132.5 mg / L, the BOD content is 30.2 mg / L, the SS content is 35.3 mg / L, the content of petroleum hydrocarbon pollutants (including alkanes, cycloalkanes and aromatics) is 57.6 mg / L, the ammonia nitrogen content is 10.2 mg / L, and the total phosphorus content is 7.3 mg / L. After being treated by this application embodiment, the COD content in the effluent of the effluent pool 7 is 5.32 mg / L, the BOD content is 2.55 mg / L, the SS content is 3.50 mg / L, the content of petroleum pollutants (including alkanes, cycloalkanes and aromatics) is 0.35 mg / L, the ammonia nitrogen content is 0.235 mg / L, and the total phosphorus content is 0.09 mg / L.

Claims

1. The AO-MBR membrane integrated sewage treatment device suitable for substations is characterized by The AO-MBR membrane integrated water treatment device comprises an inlet pool (1), an air flotation regulating pool (2), a photocatalytic reaction pool (3), an A-level anoxic pool (4), an O-level aerobic pool (5), an MBR membrane pool (6) and an outlet pool (7), wherein the inlet pool (1), the air flotation regulating pool (2), the photocatalytic reaction pool (3), the A-level anoxic pool (4), the O-level aerobic pool (5), the MBR membrane pool (6) and the outlet pool (7) are sequentially arranged in a box along a water flow direction, and adjacent pools are separated by partitions; A micro-nano bubble generator (8) is arranged at the bottom of the flotation adjustment tank (2), an ultraviolet light source (9) is arranged in the photocatalytic reaction tank (3), and a chitosan-TiO2 composite photocatalyst is added, a mesh cage is arranged in the A-level anoxic tank (4) and the O-level aerobic tank (5), and the mesh cage is filled with an artificial carrier, an aeration plate (10) is arranged at the bottom of the O-level aerobic tank (5), a membrane assembly (11) is arranged in the MBR membrane tank (6), anaerobic activated sludge is inoculated in the MBR membrane tank (6), and a disinfectant is added to the effluent tank (7); A nitrification liquid reflux port is provided on the Class O aerobic tank (5), and the nitrification liquid reflux port is connected to the liquid inlet of the Class A anoxic tank (4) through a nitrification liquid reflux pipe (13). A sludge reflux port is provided at the bottom of the MBR membrane tank (6), and a sludge inlet is provided at the bottom of the Class A anoxic tank (4). One end of the sludge reflux pipe (12) is connected to the sludge reflux port, and the other end of the sludge reflux pipe (12) is connected to the sludge inlet of the Class A anoxic tank (4). The preparation method of chitosan-TiO2 composite photocatalyst is as follows:

1. Add TiO2 powder and melamine into deionized water, stir evenly, filter and collect filter cake, dry the filter cake and grind it to obtain mixed powder, calcine the mixed powder at 500-600° C. in nitrogen atmosphere, wash and dry to obtain TiO2 / g-C3N4 composite material; 2. adding chitosan powder to 1 wt% to 4 wt% glacial acetic acid solution to obtain a chitosan solution, wherein the concentration of chitosan in the chitosan solution is 1 wt% to 4 wt%; 3. Adding the TiO2 / g-C3N4 composite material and cellulose into deionized water, uniformly dispersing by ultrasonication, and obtaining a suspension; 4. The chitosan solution and the suspension are mixed and stirred evenly, glutaraldehyde solution is added dropwise, and the reaction is carried out at 50-60° C. for 1-1.5 hours to obtain a cross-linked reaction product, the cross-linked reaction product is frozen at low temperature and then freeze-dried, and the cold trap temperature is controlled at -40° C. to -50° C. to obtain a chitosan-TiO2 composite photocatalyst.

2. The AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 1 is characterized in that A grille is arranged in the water inlet pool (1).

3. The AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 1 is characterized in that The aeration plate (10) is connected to the air pump (16) via a gas pipeline.

4. The AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 1 is characterized in that The disinfectant added into the water outlet pool (7) is sodium hypochlorite.

5. The AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 1 is characterized in that A mud discharge port is also provided at the bottom of the MBR membrane tank (6).

6. The AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 1, characterized in that Cover plates (14) are arranged on the tops of the water inlet pool (1), the air flotation adjustment pool (2), the photocatalytic reaction pool (3), the A-level anoxic pool (4), the O-level aerobic pool (5), the MBR membrane pool (6) and the water outlet pool (7).

7. A method for treating sewage using the AO-MBR membrane integrated sewage treatment device suitable for a substation as claimed in claim 1, characterized in that The method of the sewage treatment method is as follows:

1. The wastewater containing transformer insulating oil is introduced into the AO-MBR membrane integrated water treatment device, and the wastewater containing transformer insulating oil passes through the water inlet tank (1), the air flotation adjustment tank (2) and the photocatalytic reaction tank (3) in sequence. The ultraviolet light source (9) is turned on in the photocatalytic reaction tank (3), and a chitosan-TiO2 composite photocatalyst is added to carry out a photocatalytic reaction; 2. The effluent of the photocatalytic reaction pool (3) flows through the Class A anoxic pool (4) and the Class O aerobic pool (5) in sequence. In the Class O aerobic pool (5), a nitrification reaction is carried out by aerobic microorganisms. The sewage in the Class O aerobic pool (5) flows back to the Class A anoxic pool (4) through the nitrification liquid return pipe (13) for denitrification. The hydraulic retention time of the Class A anoxic pool (4) is controlled to be 2 to 5 hours, and the hydraulic retention time of the Class O aerobic pool (5) is controlled to be 4 to 8 hours. The effluent of the Class O aerobic pool (5) flows into the MBR membrane pool (6) and is denitrified by anaerobic activated sludge.

3. The effluent from the MBR membrane tank (6) flows into the effluent tank (7) for disinfection. After disinfection, the purified water is discharged to complete the treatment of the wastewater containing transformer insulating oil.

8. The method for treating sewage using the AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 7, characterized in that In step 1, when the content of transformer insulating oil in the wastewater containing transformer insulating oil is higher than 40 mg / L, the micro-nano bubble generator (8) in the flotation adjustment tank (2) is turned on.

9. The method for treating sewage using the AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 7, characterized in that In step 2, the hydraulic retention time of the Class A anoxic pool (4) is controlled to be 3 to 5 hours, and the hydraulic retention time of the Class O aerobic pool (5) is controlled to be 4 to 6 hours.

10. The method for treating sewage using the AO-MBR membrane integrated sewage treatment device suitable for a substation according to claim 7, characterized in that In step 2, the hydraulic retention time of the MBR membrane pool (6) is controlled to be 8 to 14 hours.

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