CN110790374A - Inversion A2O + composite MBR sewage treatment device and treatment method thereof - Google Patents

Abstract

The invention discloses an inverted A ² /O+ composite MBR sewage treatment device and a treatment method thereof, comprising ultrafine grids, anoxic ponds, anaerobic ponds, aerobic ponds, and composite MBR reactions arranged in sequence according to the direction of water flow The pretreated sewage passing through the ultra-fine grid is pumped into the anoxic tank, one end of the anoxic tank is connected to the subsequent treatment return sludge and the return nitrification liquid pipeline, and the effluent from the anoxic tank directly enters the anaerobic tank and the aerobic tank. One end of the oxygen tank is equipped with a nitrifying liquid return pipe to return to the anoxic tank, and the effluent from the aerobic tank enters the composite MBR reactor; the sewage treated by the three-dimensional elastic packing and membrane module in the MBR tank can be discharged, and one end of the MBR tank is equipped with a sludge return The pipeline returns to the anoxic tank, and a sludge discharge pipeline is installed to discharge the excess sludge. The invention can strengthen the denitrification and phosphorus removal effect, reduce the energy consumption of the process, and significantly improve the effluent quality standard.

Description

An inverted A2/O+ composite MBR sewage treatment device and its treatment method

technical field

The invention relates to the technical field of urban sewage treatment, in particular to an inverted A ² /O+ composite MBR sewage treatment device and a treatment method thereof.

Background technique

With the improvement of the discharge standards of urban sewage plants, the traditional sewage treatment process can no longer meet the discharge requirements, and it is urgent to upgrade the traditional sewage treatment process.

The traditional A ² /O process has three obvious shortcomings: 1) the anaerobic zone is in the front, and the nitrate in the returning sludge has an adverse effect on the anaerobic zone; 2) the anoxic zone is located in the middle of the system, and denitrification occurs in the carbon source. Disadvantages in distribution; 3) There is an internal circulation, and only a small part of the excess sludge discharged from the system actually undergoes a complete process of phosphorus release and phosphorus absorption. Therefore, an inverted A ² /O process is proposed, in which the anaerobic and anoxic positions are inverted, the carbon source of denitrification is preferentially satisfied, and the denitrification capacity is strengthened. However, the conventional inverted A ² /O process has the disadvantage of improper water distribution, and the use of In the same reflux system, the effluent stability of suspended solids is insufficient, and the denitrification efficiency is low.

MBR sewage treatment is a common method of modern sewage treatment. MBR sewage treatment is a new sewage treatment technology that combines activated sludge method and integrated submerged membrane separation system. The flow of a typical MBR system can be described as follows: Sewage After passing through the grid, it flows into the adjustment tank, and the sewage in the adjustment tank is pumped to the anoxic area, where the suspended pollutants such as starch, fiber, carbohydrates and soluble organic compounds are decomposed into organic acids, and macromolecular organic compounds are decomposed into small molecular organic compounds, insoluble Organic matter is converted into soluble organic matter. Then the sewage enters the aerobic zone for organic biodegradation, and at the same time, the biological nitrification reaction is carried out, and the denitrification is carried out by returning to the anoxic zone to complete the denitrification function. Impurities that cannot be degraded and activated sludge are separated by the membrane module and remain in the membrane tank, and the membrane filtration water is reused or discharged up to the standard. MBR sewage treatment is generally installed after biochemical treatment, replacing the traditional secondary sedimentation tank, and can carry out high-efficiency solid-liquid separation, with the advantages of stable effluent quality and less excess sludge output, but at the same time, there are also high investment, high energy consumption, and operating costs. The high level is insufficient and needs to be improved urgently.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the present invention provides an inverted A ² /O+ composite MBR sewage treatment device, which effectively solves the problem of low denitrification efficiency of the inverted A ² /O and reduces the energy consumption and operating cost in the MBR process. .

In order to achieve the above object, the present invention adopts the following technical solutions:

An inverted A ² /O+ composite MBR sewage treatment device, comprising ultra-fine grids, anoxic pools, anaerobic pools, aerobic pools and composite MBR reactors arranged in sequence according to the direction of water inflow;

The aerobic tank is provided with a nitrification liquid return pipe, and the aerobic tank is connected to the anoxic tank through the nitrification liquid return pipe; the compound MBR reactor is provided with a sludge return pipe, and the compound MBR reactor is connected to the anoxic tank through the sludge return pipe. pool; a return pump is provided on the pipeline where the nitrification liquid return pipeline and the sludge return pipeline meet, which is used to pump the nitrification liquid and sludge;

The ultra-fine grid is connected to the anoxic tank and the anaerobic tank through the water inlet pipe. There are multi-point water inlet pipes on the water inlet pipe. The sewage is respectively connected to the anoxic tank and the anaerobic tank through the multi-point water inlet pipe; Anoxic tank inlet valve is installed on the pipeline of anoxic tank to control the inflow of anoxic tank; multi-point water inlet pipe is connected to the pipeline of anaerobic tank with anaerobic tank inlet valve to control the anaerobic tank The water inlet of the oxygen tank;

The composite MBR tank includes packing cube, MBR membrane module and aeration system. The packing cube and MBR membrane module are arranged in sequence according to the direction of water flow, and the aeration system is located under the packing cube and MBR membrane module; the packing cube includes three-dimensional packing and cubic skeleton. The three-dimensional packing is fixedly installed inside the cubic frame, the aeration system includes an aeration pipe, and a grid support is installed above the aeration pipe; the cubic frame is movably connected with the grid support through a connecting buckle; the MBR membrane assembly It is also movably connected with the grille bracket through the connecting buckle;

The three-dimensional filler is formed by pressing soft aldehyde fibers on a plastic disc, the unit diameter of the three-dimensional filler is 150-200 mm, and the spacing between the three-dimensional fillers is 80-100 mm.

The packing cube of the present invention adopts the semi-fixed connection method, which is convenient for installation and disassembly, and can greatly shorten the packing replacement time. The same is true for the MBR membrane module, which shares the bracket with the aeration system, does not need repeated installation, has a simple structure and is convenient to use. In addition, the arrangement of the three-dimensional packing can make the contact with the sewage uniform and the contact area is larger. In this way, a packing cube is set at the front of the MBR tank, and the sewage first passes through the packing cube and the aeration system at the lower part of the packing to form a biofilm on the surface, which is used as the pretreatment of the membrane module, and then enters the membrane module system to reduce the pressure of the membrane module. Reducing the return of activated sludge can greatly reduce the energy consumption of the MBR tank; and the return of the sludge and the return of the nitrification solution share a pump system, which further reduces the energy consumption.

Preferably, the connecting buckle is a pulley and a buckle.

Preferably, the distance between the grid bars of the ultra-fine grid is 0.2-2 mm, and the interval between the ultra-fine grid is 0.1 mm.

Preferably, the MBR membrane module is a hollow fiber membrane module or a flat membrane module.

Preferably, the MBR membrane module is mainly composed of membranes, and the effective distance between the membranes is greater than 100 mm.

Preferably, the diameter of the aeration pipe is 15-20mm, the openings are on the same axis, the openings are 2-4mm, and the perforation spacing is 100-150mm.

Preferably, the designed membrane flux of the composite MBR pool is increased by 30% to 50% on the basis of the factory design margin.

The invention also provides an inverted A ² /O+ composite MBR sewage treatment method, which has low operation cost and good treatment effect.

The inverted A ² /O+ composite MBR sewage treatment method comprises the following steps:

Step 1: The pretreated sewage passes through the ultra-fine grid to retain tiny suspended solids, fibers and other impurities in the sewage;

Step 2: Then the sewage flows through the anoxic tank, the anaerobic tank, and the aerobic tank in turn for denitrification and phosphorus removal; when the C:N:P of the anaerobic tank does not meet the 100:5:1 ratio, the anaerobic tank is opened to enter. The water valve makes the sewage treated in step 1 flow into the anaerobic tank to supplement the carbon source until the C:N:P is 100:5:1, and close the water inlet valve of the anaerobic tank;

Step 3: pump the sewage after denitrification and phosphorus removal into the composite MBR reactor; the reflux pump sucks the nitrification mixture in the aerobic tank, and returns the nitrification mixture to the anoxic tank through the nitrification liquid return pipeline;

Step 4: The sewage entering the composite MBR reactor is contacted and oxidized by the packing cube, enhanced by the aeration system and filtered by the MBR membrane module, and the water is discharged; The sludge is returned to the anoxic tank.

Anoxic tank receives raw sewage, compound MBR reactor return sludge and aerobic tank return nitrification solution, denitrifying bacteria in anoxic tank use organic matter in sewage as carbon source, NO ₃ ^- -N and NO ₂ ^- - N is reduced to N ₂ and released to the air; the anaerobic tank receives sludge and sewage rich in phosphorus-accumulating bacteria after denitrification in the anoxic tank, and at the same time adopts a multi-point water inflow method, and feeds the raw sewage according to the water quality to supplement the carbon source, The anaerobic tank mainly carries out the phosphorus release process, the composite MBR reactor receives the effluent from the aerobic tank, and the sewage is contacted and oxidized by the packing cube to the membrane module system, and the water is filtered by the membrane module system.

Preferably, 80%-120% of the nitrification mixed solution is returned to the anoxic tank, and 150%-180% of the sludge is returned to the anoxic tank.

Preferably, the hydraulic retention time of the anoxic pool is 0.5-2.5 h, the hydraulic retention time of the anaerobic pool is 1-2 h, the hydraulic retention time of the aerobic pool is 2.5-4 h, and the hydraulic retention time of the compound MBR pool is 0.5-1.5 h.

Preferably, in step 4, the ratio of soda to water is 24:1, and the dissolved oxygen is controlled at 3-5mg/L; the aeration blower adopts frequency conversion speed regulation technology. Controlling the ratio of soda to water and the amount of dissolved oxygen within a certain range can achieve a balance between the effect of operating costs and avoid energy waste.

Preferably, the wrapping of the MBR membrane module is sprayed with a high-pressure water gun or tap water, and the processing capacity of a single membrane is less than 1.5 m ³ /hr.

The present invention overcomes the problem of low denitrification efficiency of A ² /O by carrying out technical innovation on the existing inverted A ² /O process, by changing the water inflow mode and updating parameters: the inversion method is adopted to avoid inversion and increase the denitrification efficiency. reduce. Control the proportion of sewage entering the anoxic and aerobic tanks according to the water quality of the sewage to ensure that the carbon source meets the needs of nitrification and denitrification without overflowing. In the process, the activated sludge undergoes all the processes of phosphorus release and phosphorus absorption, and has the "high" in phosphorus removal. Group effect”, the phosphorus removal effect is significantly improved, and the anoxic zone is located at the beginning of the process, allowing denitrification to preferentially obtain carbon sources, further enhancing the denitrification capacity of the system.

The invention adopts a composite MBR process, combines biological contact oxidation with membrane components, innovatively introduces removable packing cubes to be placed in front of the membrane components, and combines with the aeration system to reduce the pressure of the membrane components, improve the performance of the membrane components, and clean and replace them. frequency, while reducing the return flow of activated sludge, greatly reducing energy consumption. The sludge return system and the aerobic nitrification liquid return are combined, and the two share a return pump system, which not only reduces the project cost, but also further reduces the operating energy consumption. In addition, through the design of the diaphragm and the adjustment of the aeration environment, etc., the comprehensive sewage treatment capacity of the present invention is optimized, energy is saved, costs are saved, and economic benefits are improved at the same time.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

FIG. 2 is a schematic diagram of the device structure of the present invention.

Figure 3 shows the layout of the packing cube and aeration system.

Among them, the meanings of each number are as follows: 1. Ultrafine grid; 2. Anoxic tank; 3. Anaerobic tank; 4. Aerobic tank; 5. Composite MBR tank; 11. Inlet pipe; Pump; 13. Multi-point water inlet pipe; 21. Anoxic tank inlet valve; 22. Sludge return valve; 23. Nitrification liquid return valve; 24. Return pump; 31. Anaerobic tank inlet valve; Pool sewage pump; 42, aerobic tank outlet pipe; 43, nitrification liquid return pipe; 51, packing cube; 52, MBR membrane module; 53, aeration system; 54, sludge return pipe; 55, sludge discharge pipe; 56, self-priming pump; 511, three-dimensional packing; 512, cubic frame; 513, connection buckle; 514, grille bracket; 531, aeration pipe.

Detailed ways

In order to make the purpose and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as herein, are not to be taken in an idealized or overly formal sense. explain.

Example 1

As shown in Figure ¹ , an inverted A2/O+ composite MBR device includes ultrafine grids 1, anoxic pools 2, anaerobic pools 3, aerobic pools 4 and composite MBR pools arranged in sequence according to the direction of water flow 5.

As shown in Figure 2, the ultra-fine grids 1 are arranged in parallel, and the distance between the two grids is 0.1 mm. The ultra-fine grid 1 is composed of grid bars, and the distance between the grid bars is 0.2-2 mm, which is used to filter finer pretreated water. of particulate matter.

The ultra-fine grid 1 is connected to the anoxic tank 2 and the anaerobic tank 3 through the water inlet pipe 11. The water inlet pipe 11 is provided with a multi-point water inlet pipe 13, and the sewage is respectively connected to the anoxic tank 2 and the anaerobic tank through the multi-point water inlet pipe 13. Pool 3; the multi-point water inlet pipe 13 is connected to the anoxic tank 2 with an anoxic tank inlet valve 21 for controlling the water inflow of the anoxic tank 2; the multi-point water inlet pipe 13 is connected to the anaerobic tank 3 An anaerobic tank inlet valve 31 is arranged on the pipeline to control the water inflow of the anaerobic tank 3;

The anoxic tank 2, the anaerobic tank 3, and the aerobic tank 4 are arranged in order according to the direction of water inflow. Contrary to the traditional AAO, the anoxic tank 2 is placed before the anaerobic tank 3, the carbon source of denitrification is preferentially satisfied, and the denitrification capacity is strengthened; The phosphorus absorption power formed under anaerobic conditions can be more fully utilized.

The aerobic pool 4 is connected to the composite MBR pool 5 through the aerobic pool outlet pipe 42, and an aerobic pool sewage pump 41 is provided on the aerobic pool water outlet pipe 42 to suck the sewage into the composite MBR pool 5; the aerobic pool 4 One end is also connected to the anoxic tank 2 through the nitrifying liquid return pipeline 43, on which a nitrifying liquid return valve 23 is arranged. One end of the composite MBR tank 5 is provided with a sludge return pipeline 54 , which is connected to the anoxic tank 2 through the sludge return valve 22 , so that the sludge is returned to the anoxic tank 2 . A return pump 24 is provided on the pipe where the nitrification liquid return pipe 43 and the sludge return pipe 54 are merged, and is used for pumping the nitrification liquid and sludge.

The composite MBR tank 5 also has a sludge discharge pipeline 55 and a self-priming pump 56. The sludge discharge pipeline 55 is used for discharging excess sludge, and the self-priming pump 56 is used for pumping clean water.

The composite MBR tank 5 includes a packing cube 51 , an MBR membrane assembly 52 and an aeration system 53 , and the packing cube 51 and the MBR membrane assembly 52 are arranged in sequence according to the direction of water flow.

As shown in FIG. 3 , the aeration system 53 includes an aeration pipe 531 , and a grill support 514 is installed above the aeration pipe 531 . The packing cube 51 is movably connected with the grid support 514 through the connecting buckle 513; the MBR membrane assembly 52 is also movably connected with the grill supporting 514 through the connecting buckle 513; the aeration system 53 is installed on the packing cube 51 and Below the MBR membrane assembly 52 . The connection buckle 513 in this embodiment is a pulley and a buckle, of course, the connection buckle of the present invention is not limited to this.

The packing cube 51 includes a three-dimensional packing 511 and a cubic frame 512 , and the three-dimensional packing 511 is fixedly installed inside the cubic frame 512 . The three-dimensional filler 511 is formed by pressing soft aldehyde fibers on a plastic disc, the unit diameter of the three-dimensional filler 511 is 150-200 mm, and the spacing between the three-dimensional fillers 511 is 80-100 mm. This embodiment utilizes the biofilm produced by the contact between the three-dimensional elastic filler and the sewage to further strengthen the denitrification and phosphorus removal effect in an aerobic environment, while reducing the pressure load of the rear MBR membrane module, reducing the cleaning frequency of the MBR membrane module, and increasing the service cycle.

The MBR membrane assembly 52 is composed of a plurality of membrane sheets, and the gap between each membrane sheet and the packing cube 51 corresponds to one aeration pipe 531 . For the MBR membrane module 52, a hollow fiber membrane module or a flat membrane module can be selected according to the actual sewage conditions. In the membrane module 52 system, the effective distance between the membranes is greater than 100mm, and the membrane module wrapping accumulation needs to be sprayed with a high-pressure water gun or tap water to a certain extent, and the processing capacity of a single membrane module is less than 1.5m ³ /hr.

Said aerobic tank 4 nitrification liquid return and composite MBR tank 5 sludge return and discharge adopt the same set of return pump system, and use return pump 24 to achieve the purpose of energy saving.

The above-mentioned inverted A ² /O+ composite MBR sewage treatment method comprises the following steps:

After the sewage is pretreated, it passes through the ultra-fine grid 1 to retain tiny suspended solids, fibers and other impurities in the sewage.

The sewage passes through the inlet pipe 11 and is pumped into the anoxic tank 2 by the inlet pipe sewage pump 12. The denitrifying bacteria in the anoxic tank use the organic matter in the sewage as a carbon source to reduce NO ₃ ^- -N and NO ₂ ^- -N to N ₂ Release to air.

The effluent of the anoxic tank 2 enters the anaerobic tank 3, and the anaerobic tank 3 receives the sludge and sewage rich in phosphorus-accumulating bacteria after denitrification from the anoxic tank. At :5:1, the carbon source is supplemented and the raw sewage is fed into the raw sewage to supplement the carbon source according to the water quality. The anaerobic tank mainly performs the phosphorus release process.

The aerobic tank receives the effluent of the anaerobic tank, the organic nitrogen in the aerobic tank is ammoniated and then nitrified, the phosphorus concentration decreases with the intake of phosphorus accumulating bacteria, and the nitrification mixture of the aerobic tank is returned to the anoxic tank in proportion. The aerobic tank 4 returns the nitrifying liquid to the anoxic tank 2 through the nitrifying liquid return pipeline 43 to supplement nitrate nitrogen.

After the sewage passes through the anoxic tank 2, the anaerobic tank 3, and the aerobic tank 4 for denitrification and phosphorus removal, it enters the composite MBR tank 5 through the outlet pipe 42 of the aerobic tank. The component 52 is filtered to meet the discharge standard, and the water is discharged through the self-priming pump 56 . The return pump 24 sucks the sludge in the composite MBR reactor 5 , and returns the sludge to the anoxic tank 2 through the sludge return pipeline 43 ; the excess sludge is discharged through the sludge discharge pipeline 55 .

The sludge in the composite MBR tank 5 is returned to the anoxic tank 2 in proportion, and the excess sludge is discharged through the sludge discharge pipeline 55 .

The return ratio of the nitrification solution from the aerobic tank 4 to the anoxic tank 2 is 80%-120%; the return ratio of the activated sludge from the composite MBR tank 5 to the anoxic tank is 150%-180%.

The hydraulic retention time of anoxic pool is 0.5-2.5h, the hydraulic retention time of anaerobic pool is 1-2h, the hydraulic retention time of aerobic pool is 2.5-4h, and the hydraulic retention time of compound MBR pool is 0.5-1.5h.

The designed membrane flux of the composite MBR pool 5 should be increased by 30% to 50% on the basis of the factory design allowance; the diameter of the aeration perforated pipe of the composite MBR pool 5 should be 15-20mm, and the openings should be on the same axis. The opening is 2-4mm, the perforation spacing is 100-150mm, the aeration volume is estimated according to the empirical value, the ratio of soda to water is 24:1, and the dissolved oxygen is controlled at 3-5mg/L; the aeration blower adopts the frequency conversion speed regulation technology.

Example 2

Using the device and method of Example 1 to treat the pretreated domestic sewage, the specific process conditions: hydraulic retention time 7.5h, MBR pool hydraulic retention time 1.5h, nitrification solution reflux ratio of 120%; The ratio is 180%; the diameter of the three-dimensional elastic packing unit of the composite MBR pool is 200mm, and the packing spacing is 80mm; the flat membrane is used, and the design allowance of the membrane flux is increased by 30%; The processing capacity of the module is less than 1.2m ³ /hr; the diameter of the aeration perforated pipe is 20mm, the opening is 2mm, the perforation spacing is 100mm, the steam-water ratio is 24:1, and the dissolved oxygen is controlled at 3-5mg/L.

The scale of the sewage plant is 20,000 tons/day. The average influent water is COD 352.5mg/L, BOD ₅ 124.7mg/L, ammonia nitrogen 25.6mg/L, total nitrogen 32.2mg/L, and total phosphorus 4.1mg/L.

The effluent water quality is COD 20.5mg/L, BOD ₅ 3.2mg/L, ammonia nitrogen 1.6mg/L, total nitrogen 2.0mg/L, total phosphorus 0.18mg/L, and the effluent quality reaches the quasi-IV class water standard.

Example 3

The influent water quality of a sewage plant is: average COD 422.4mg/L, BOD ₅ 141.9mg/L, ammonia nitrogen 28.3mg/L, total nitrogen 36.2mg/L, and total phosphorus 5.6mg/L.

The original sewage treatment process of this sewage plant is A ² /O+MBR process, the treatment scale is 10,000 tons/day, the hydraulic retention time is 9h, the hydraulic retention time of the MBR tank is 2h, the nitrifying solution reflux ratio is 200%, and the activated sludge reflux ratio is 200%. 200%, hollow fiber membrane is selected, the processing capacity of a single membrane module is less than 1.0m ³ /hr, the diameter of the aeration perforated pipe is 18mm, the opening is 1.8mm, the perforation spacing is 150mm, and the steam-water ratio is 24:1. After being treated by the original sewage treatment process of the sewage treatment plant, the effluent water quality is COD 50.5mg/L, BOD ₅ 10.4mg/L, ammonia nitrogen 4.8mg/L, total nitrogen 13.5mg/L, and total phosphorus 0.48mg/L, which meet the first grade. aEmission standards.

According to the structure of Example 1, the original sewage treatment process of the sewage treatment plant is transformed: the biochemical tank changes the order of water in and out of the pipeline, and the inverted A ² /O process does not need to build a new tank, and the original aeration mode of the MBR tank remains unchanged, The parameters of the membrane module are optimized, and the packing cube of the present invention is arranged at the front of the membrane module. After the transformation, the hydraulic retention time is 8h, the hydraulic retention time of the MBR tank is 1.5h, the reflux ratio of nitrification solution is 100%; the reflux ratio of activated sludge is 150%; the diameter of the three-dimensional elastic packing unit of the composite MBR tank is 200mm, and the packing spacing is 100mm; For membrane modules and aeration systems, the parameters of membrane modules are optimized, and the design margin of membrane flux is increased by 35%; the processing capacity of a single membrane module is less than 1.2m ³ /hr. The original sewage treatment process of the sewage plant is transformed into the structure of the present invention. After the sewage is treated, the effluent quality is COD 32.3mg/L, BOD ₅ 8.9mg/L, ammonia nitrogen 1.9mg/L, total nitrogen 2.3mg/L, total nitrogen Phosphorus 0.36mg/L, which can reach the standard of surface V water.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined according to the claims.

Claims (10)

1. an inverted A ² /O+ composite MBR sewage treatment device, is characterized in that, comprises the superfine grille (1), anoxic pond (2), anaerobic pond (3) that are arranged successively by the direction of water intake, an aerobic pool (4) and a composite MBR reactor (5); The aerobic tank (4) is provided with a nitrifying liquid return pipeline (43), and the aerobic tank (4) is connected to the anoxic tank (2) through the nitrifying liquid return pipeline (43); the composite MBR reactor (5) is provided with a sewage The sludge return pipeline (54), the composite MBR reactor (5) is connected to the anoxic tank (2) through the sludge return pipeline (54); A return pump (24) is provided on the pipeline for pumping nitrification liquid and sludge; The ultra-fine grid (1) is connected to the anoxic tank (2) and the anaerobic tank (3) through the water inlet pipe (11). The water pipes (13) are respectively connected to the anoxic tank (2) and the anaerobic tank (3); an anoxic tank inlet valve (21) is provided on the pipeline connecting the multi-point water inlet pipe (13) to the anoxic tank (2) , used to control the inflow of the anoxic tank (2); the multi-point water inlet pipe (13) connected to the anaerobic tank (3) is provided with an anaerobic tank inlet valve (31) for controlling the anaerobic tank (31) (3) water intake; The composite MBR tank (5) includes a packing cube (51), an MBR membrane module (52) and an aeration system (53). 53) is located below the packing cube (51) and the MBR membrane assembly (52); the packing cube (51) includes a three-dimensional packing (511) and a cubic frame (512), and the three-dimensional packing (511) is fixedly installed on the cubic frame (512) ) inside, the aeration system (53) includes an aeration pipe (531), and a grill bracket (514) is installed above the aeration pipe (531); the cubic frame (512) is connected to the grille through a connection buckle (513) The bracket (514) is movably connected; the MBR membrane assembly (52) is also movably connected with the grid bracket (514) through the connection buckle (513); The three-dimensional filler (511) is formed by pressing soft aldehyde fibers on a plastic disc, the unit diameter of the three-dimensional filler (511) is 150-200mm, and the spacing between the three-dimensional fillers (511) is 80-100mm. ^2. The inverted A2/O+ composite MBR sewage treatment device according to claim 1, characterized in that: the connection buckle (513) is a pulley and a buckle. 3. The inverted A ² /O+ composite MBR sewage treatment device according to claim 1, wherein the distance between the grid bars of the ultra-fine grid (1) is 0.2-2 mm, and the distance between the grid bars of the ultra-fine grid (1) is 0.2-2 mm. The interval is 0.1mm. 4. The inverted A2/O ⁺ composite MBR sewage treatment device according to claim 1, wherein the MBR membrane assembly (52) is mainly composed of diaphragms, and the effective distance between the diaphragms is greater than 100mm. 5. The inverted A2/O ⁺ composite MBR sewage treatment device according to claim 1 or 4, characterized in that: the designed membrane flux of the composite MBR pool (5) is increased by 30%～30% on the basis of the factory design allowance 50%. 6. the sewage treatment method of a kind of inverted A ² /O+ composite MBR sewage treatment device according to claim 1, is characterized in that, comprises the following steps: Step 1: The pretreated sewage passes through the ultra-fine grid (1) to retain tiny suspended solids, fibers and other impurities in the sewage; Step 2: Then the sewage flows through the anoxic tank (2), the anaerobic tank (3), and the aerobic tank (4) in turn to remove nitrogen and phosphorus; when the C:N:P of the anaerobic tank (3) is not satisfied At 100:5:1, open the water inlet valve (31) of the anaerobic tank so that the sewage treated in step 1 flows into the anaerobic tank (3), and supplement the carbon source until the C:N:P is 100:5:1, Close the water inlet valve (31) of the anaerobic tank; Step 3: pumping the denitrified and dephosphorized sewage into the composite MBR reactor (5); the reflux pump (24) sucks the nitrification mixed solution in the aerobic tank (4), and passes through the nitrification solution return pipeline (43) Return the nitrification mixture to the anoxic tank (2); Step 4: The sewage entering the composite MBR reactor (5) is contacted and oxidized by the packing cube (51), enhanced by the aeration system (53) and filtered by the MBR membrane module (52), and the water is discharged; the return pump (24) sucks the composite The sludge in the MBR reactor (5) is returned to the anoxic tank (2) through the sludge return pipe (43). 7. An inverted A ² /O+ composite MBR sewage treatment method according to claim 6, characterized in that the nitrification mixed solution is refluxed by 80% to 120% to the anoxic tank (2), and the 150% to 180% of the sludge is returned to the anoxic tank (2). 8 . An inverted A ² /O+ composite MBR sewage treatment method according to claim 6 , wherein the anoxic tank (2) has a hydraulic retention time of 0.5-2.5 h, and the anaerobic tank (3) has a hydraulic retention time of 0.5-2.5 h. 9 . 1～2h, the hydraulic retention time of the aerobic pool (4) is 2.5～4h, and the hydraulic retention time of the compound MBR pool (5) is 0.5～1.5h. 9. a kind of inverted A ² /O+ composite MBR sewage treatment method according to claim 6, is characterized in that, in step 4, the ratio of soda to water is 24:1, and dissolved oxygen is controlled at 3-5mg/L; Aeration blower Adopt frequency conversion speed regulation technology. 10. a kind of inverted A ² /O+ composite MBR sewage treatment method according to claim 6, is characterized in that, the wrapping of MBR membrane module (52) is sprayed with high-pressure water gun or tap water, and the processing capacity of single membrane Below 1.5m ³ /hr.

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