A2O domestic sewage treatment system and method and novel aeration device

Abstract

The invention discloses a novel aeration device which comprises a sewage pump, an air compressor, an air guide pipe, an air flow control valve, an axial center gas filling mechanism, a static spiral cutter and a sewage pipeline, one end of the sewage pump is connected into a sewage inlet, and the other end of the sewage pump is connected with the sewage pipeline through the static spiral cutter to discharge sewage. The axial center gas filling mechanism is arranged at the front end of the static spiral cutter and connected with the air compressor through the gas guide pipe, and the gas flow control valve is arranged on the gas guide pipe. The static spiral cutter comprises a cutting pipe, a mandrel is arranged in the center of the cutting pipe, a plurality of cutting blades which are sequentially stacked are arranged on the mandrel and penetrate through the mandrel through a middle hole, and the adjacent cutting blades are staggered by angles and axially arranged according to a spiral line equation in a variable-pitch mode to form a space spiral structure. The screw pitch of the spatial spiral structure is gradually reduced from the water inlet end to the water outlet end. The problems that an existing sewage treatment system is poor in aeration effect, high in energy consumption and inconvenient to install are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to an A2O domestic sewage treatment system, method and a novel aeration device. Background Art

[0002] The traditional activated sludge process is the earliest applied process, and it has a high efficiency in removing organic matter. In the past 20 years, the harm of eutrophication of water bodies has become more and more serious, and the removal of nitrogen and phosphorus has been included in the goals of sewage treatment. As a result, the improved AO process and A2O process of the activated sludge process have emerged. There are two types of AO processes, one is the anaerobic-aerobic process for phosphorus removal, and the other is the anoxic-aerobic process for nitrogen removal; the A2O process is a process for both nitrogen removal and phosphorus removal. But no matter which process is used, aeration of aerobic tanks is an indispensable and important link, which has a significant impact on the efficiency and quality of sewage treatment. There are currently three main schemes for aeration of aerobic tanks:

[0003] The first one is the contact oxidation process.

[0004] Advantages: ① High sewage treatment efficiency; ② Wide range of process applications; ③ No sludge bulking and sludge reflux, easy management; ④ Resistant to flushing, strong adaptability; ⑤ Obvious energy-saving effect; ⑥ Low sludge output,

[0005] Disadvantages: ① The actual amount of biofilm on the filler varies with the load, which will lead to poor sedimentation effect in subsequent processes; ② The process is relatively complicated; ③ Water distribution and aeration are not easy to be uniform, and dead zones are prone to occur; ④ The layout in the pool is relatively complex, and the installation and maintenance of the aeration equipment are relatively cumbersome.

[0006] The second is the circulating SBR biological treatment process.

[0007] Advantages: ① The primary sedimentation tank, secondary sedimentation tank, sludge return system and sludge digestion system are omitted, the process flow is simple, and maintenance and management are convenient; ② The mechanical equipment is few in type and simple, and is not prone to failure, requiring less maintenance; ③ There are fewer structures, the biological pool is compactly arranged, and it occupies less space; ④ It can withstand a certain amount of water impact load and has a greater dilution capacity for high-concentration industrial wastewater; ⑤ If the operating control conditions are proper, a good denitrification effect can be obtained; ⑥ Low investment, low energy consumption, and low operating cost; ⑦ It takes less space,

[0008] Disadvantages: ① Due to the alternating aeration operation of one pool, the utilization rate of the aeration equipment in the pool is low; ② Aeration uses underwater aeration heads, which have a larger maintenance workload than oxidation ditches, and a series of operations need to be stopped during maintenance, affecting the effluent quality of the treatment plant; ③ The maintenance workload of equipment, aeration heads, etc. is higher than that of oxidation ditches, and the maintenance cost is high; ④ The automatic control level requirements are high, and it cannot operate without automatic control; ⑤ The effluent quality is greatly affected by operation control; ⑥ There is often scum on the water surface of the SBR pool, which can only be removed manually, and the workload is large.

[0009] The third is the MBR membrane process.

[0010] Advantages: ① Due to the efficient separation of the membrane, the separation effect is much better than that of the old sedimentation tank, and the effluent water quality is stable. ② The process parameters are easy to control, and the complete separation of HRT and SRT is achieved; ③ The equipment is compact, eliminating the secondary sedimentation tank, occupying a small area, and is not restricted by the location of the installation; ④ The process has low residual sludge production, reducing the cost of sludge treatment. ⑤ It is helpful to intercept, grow and reproduce the slow-growing nitrifying bacteria; ⑥ It overcomes the sludge expansion phenomenon that easily occurs in the conventional activated sludge method; ⑦ It is easy to operate and manage, and easy to realize automatic control.

[0011] Disadvantages: ① The cost of MBR membrane process is relatively high; ② Membrane pollution occurs easily, which brings inconvenience to operation and management and requires regular cleaning; ③ The operating cost of MBR process is high. High energy consumption and membrane cleaning are the reasons for the high operating cost of MBR.

[0012] Due to its many advantages such as high sewage treatment efficiency, wide range of process application, strong adaptability, etc., the first contact oxidation process mentioned above is still the most widely used aeration method for sewage treatment. However, the main implementation method is through traditional bottom aeration. At present, the bottom aeration technology mainly adopts two methods: bottom microporous aeration and bottom center blower aeration. However, no matter which method is used, it cannot effectively solve the current contact oxidation process. The problems that exist in ① the actual number of biofilms on the filler varies with the load, which will lead to poor sedimentation effect in subsequent processes; ② the process is relatively complicated; ③ water distribution and aeration are not easy to be uniform, and dead zones are prone to occur; ④ the layout in the pool is relatively complicated, and the installation and maintenance of the aeration equipment are relatively cumbersome. Summary of the invention

[0013] The purpose of the present invention is to provide a novel aeration device for use in a domestic sewage treatment system to solve the problems of poor aeration effect, high energy consumption and inconvenient installation in existing sewage treatment.

[0014] In order to solve the above problems, the present invention discloses a novel aeration device, comprising: a sewage pump, an air compressor, an air guide pipe, a gas flow control valve, an axial center gas filling mechanism, a static spiral cutter and a sewage pipe, one end of the sewage pump is connected to a sewage inlet, and the other end is connected to the sewage pipe through the static spiral cutter to discharge the sewage, the axial center gas filling mechanism is arranged at the front end of the static spiral cutter, the axial center gas filling mechanism is connected to the air compressor through the air guide pipe, and the gas flow control valve is arranged on the air guide pipe.

[0015] Preferably, the static spiral cutter includes a cutting tube, a core shaft is arranged in the center of the cutting tube, and a plurality of cutting blades stacked in sequence are arranged on the core shaft and passed through the middle hole on the core shaft. Adjacent cutting blades are staggered at angles and arranged axially with variable pitches according to the spiral line equation to form a spatial spiral structure, and the surface of the spatial spiral structure is stepped.

[0016] Preferably, the pitch of the spatial spiral structure gradually decreases from the water inlet end to the water outlet end.

[0017] Preferably, the axial center gas filling mechanism includes a mounting pipe seat, a gas connecting pipe, a fixed seat, a gas one-way valve, an air outlet nozzle and an air inlet flange pipe. The mounting pipe seat is installed on the air inlet flange pipe, and the gas connecting pipe is installed on the mounting pipe seat through the fixed seat. The gas one-way valve is arranged in the gas connecting pipe. A air outlet nozzle is arranged at the outlet of the gas connecting pipe, and the center of the air outlet nozzle corresponds to the center of the core shaft.

[0018] Preferably, a guide cone is provided at the water inlet end of the core shaft, and the guide cone corresponds to the air outlet nozzle.

[0019] The novel aeration device of the present invention cuts oxygen macromolecules in the air into nano-scale small molecular mass substances through a static spiral cutting device without a rotating power mechanism, which can promote their dissolution in water at normal temperature and pressure, with a fast oxygenation speed, high dissolved oxygen content and good stability; the static spiral cutting device has no power rotating mechanism, low equipment cost, easy maintenance, and greatly improves the structure of the traditional aeration system.

[0020] The cutting blades can achieve micro-nano cutting and refinement of gas and liquid. The large bubbles in the liquid are subjected to shear force on the spatial spiral surface formed by the cutting blades. The flow field boundary is the stepped cutting edge formed by the spiral of the cutting blades. Under the action of a certain speed of flow field and centrifugal force, the gas-water mixture is subjected to the stepped cutting force on the spiral surface, which can theoretically achieve cutting on an infinitely small scale.

[0021] The axial center aeration mechanism adopts a specially designed coaxial air outlet nozzle. According to the fluid mechanics theory analysis of fluid flowing around a cylinder, the water flow rate in the area near the aeration hole is close to 0, and oxygen can be smoothly dissipated into the water, thereby ensuring the air intake in the pipeline. This aeration method is highly efficient.

[0022] The present invention also discloses an A2O domestic sewage treatment system, which uses the novel aeration device, and comprises a sewage inlet pump, an anaerobic zone, an anoxic zone, an aerobic zone, an internal reflux pump, a secondary sedimentation zone, a sludge discharge valve, a sludge reflux pump and a control system. The anaerobic zone, the anoxic zone, the aerobic zone and the secondary sedimentation zone are connected in sequence. The sewage inlet pump is used to transport sewage to the anaerobic zone. The sewage pump is connected to the anoxic zone. The sewage pipe is connected to the aerobic zone. The internal reflux pump connects the aerobic zone and the anoxic zone. One side of the sludge outlet of the secondary sedimentation zone discharges sludge through the sludge discharge valve, and the other side is connected to the entrance of the anaerobic zone through the sludge reflux pump. The control system is connected to the sewage pump, the sewage inlet pump and the internal reflux pump.

[0023] As a further improvement of the above technical solution:

[0024] The anaerobic zone and the anoxic zone are provided with stirring blades.

[0025] The present invention also discloses a method for treating A2O domestic sewage, comprising the following steps:

[0026] The sewage passes through the anaerobic zone, anoxic zone, aerobic zone and secondary sedimentation zone in sequence to obtain clear liquid and sludge. The clear liquid is discharged, part of the sludge is discharged through the sludge discharge valve, and part of the sludge is returned to the anaerobic zone through the sludge return pump; at the same time,

[0027] The sewage pump draws sewage from the anoxic zone, generates micro-nano bubbles under the action of the axial central aeration mechanism and the static spiral cutter, and then enters the aerobic zone for aeration.

[0028] As a further improvement of the above technical solution:

[0029] It also includes stirring blades that drive sewage stirring in the anaerobic zone and the anoxic zone.

[0030] The nitrification liquid produced in the aerobic zone flows back to the anoxic zone to form internal reflux.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] High-efficiency aeration: The novel aeration device of the present invention can generate micro-nano bubbles through the cooperation of the axial central aeration mechanism and the static spiral cutter, thereby improving the oxygen transfer efficiency, thereby enhancing the biochemical treatment effect of the aerobic zone and improving the removal rate of COD (chemical oxygen demand) and ammonia nitrogen.

[0033] Energy saving and consumption reduction: The setting of the gas flow control valve can accurately control the gas supply of the air compressor, avoid excessive gas supply and reduce energy consumption.

[0034] High space utilization: The spiral structure design of the static spiral cutter enables the sewage to be cut and aerated during the flow process, saving space and improving the compactness of the treatment system.

[0035] Easy maintenance: The new aeration device has a simple structure and is easy to disassemble and maintain, reducing the complexity and cost of daily operation and maintenance.

[0036] Sludge return optimization: The sludge in the secondary sedimentation area is returned to the anaerobic area through the sludge return pump, which improves the utilization rate of the sludge and enhances the nitrogen and phosphorus removal effect of the system.

[0037] Even stirring: The stirring blades installed in the anaerobic zone and the anoxic zone can effectively stir the sewage, improve the mixing degree of sludge and sewage, and facilitate the biochemical reaction.

[0038] Stable treatment effect: Through the integrated management of the control system, the automation of sewage treatment is realized, ensuring the stability of the treatment effect.

[0039] Environmentally friendly: The sewage treatment system of this embodiment effectively removes harmful substances in sewage, reduces pollution to the environment, and is conducive to the recycling of water resources.

[0040] Wide applicability: The system is suitable for A2O domestic sewage treatment of various scales, has good adaptability, and can meet the treatment needs of different occasions.

[0041] Safe and reliable: The setting of the gas one-way valve ensures the unidirectional flow of gas, prevents sewage backflow, and improves the safety and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the structure of the A2O domestic sewage treatment system of the present invention;

[0043] Figure 2 It is a schematic diagram of the structure of the axial center gas filling mechanism and the static spiral cutter of the present invention;

[0044] Figure 3 It is a schematic diagram of the structure of the static spiral cutter of the present invention.

[0045] Figure numerals: 1. Sewage inlet pump; 10. Control system; 11. Secondary sedimentation zone; 12. Mud discharge valve; 13. Aerobic zone; 14. Sludge return pump; 15. Anoxic zone; 16. Internal return pump; 17. Anaerobic zone; 2. Mixing blade; 3. Sewage pump; 4. Air compressor; 5. Air guide pipe; 6. Gas flow control valve; 7. Axial center gas filling mechanism; 71. Mounting pipe seat; 72. Gas connecting pipe; 74. Fixed seat; 75. Gas check valve; 76. Air outlet nozzle; 77. Inlet flange pipe; 8. Static spiral cutter; 81. Guide cone; 82. Cutting pipe; 83. Mandrel; 84. Cutting blade; 85. Connecting flange; 86. Press block; 87. Locking nut; 9. Sewage pipe. DETAILED DESCRIPTION

[0046] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0047] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] The following will be combined with the drawings in 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.

[0050] like Figure 1 As shown, this embodiment discloses an A2O domestic sewage treatment system, including a sewage inlet pump 1, an anaerobic zone 17, an anoxic zone 15, an aerobic zone 13, an internal reflux pump 16, a secondary sedimentation zone 11, a sludge valve 12, a sludge reflux pump 14 and a control system 10. The anaerobic zone 17, the anoxic zone 15, the aerobic zone 13 and the secondary sedimentation zone 11 are connected in sequence. The sewage inlet pump 1 is used to transport sewage to the anaerobic zone 17. The difference is that: this embodiment includes a new aeration device, and the new aeration device includes: a sewage pump 3, an air compressor 4, an air guide pipe 5, a gas flow control valve 6, an axial center gas filling mechanism 7, a static spiral cutter 8 and a sewage pipe 9. One end of the sewage pump 3 is connected to the sewage inlet, and the other end is connected to the sewage pipe 9 through the static spiral cutter 8 to discharge the sewage. The axial center gas filling mechanism 7 is arranged at the front end of the static spiral cutter 8, and the axial center gas filling mechanism 7 is connected to the air compressor 4 through the air guide pipe 5. The gas flow control valve 6 is arranged on the air guide pipe 5.

[0051] like Figure 2 and 3 As shown, the static spiral cutter 8 includes a cutting tube 82, a core shaft 83 is arranged in the center of the cutting tube 82, and a plurality of cutting blades 84 are arranged on the core shaft 83 and are stacked in sequence. The cutting blades 84 are inserted through the middle hole on the core shaft 83, and the adjacent cutting blades 84 are staggered at an angle and arranged axially with variable pitch according to the spiral equation to form a spatial spiral structure. The surface of the spatial spiral structure is stepped. The cutting blades 84 are fixed on the core shaft 83 by a pressing block 86 and a locking nut 87. They are connected to other pipes by a connecting flange 85. The thickness of the cutting blades 84 is 0.08 mm.

[0052] The pitch of the spatial spiral structure gradually decreases from the water inlet end to the water outlet end. The axial center gas filling mechanism 7 includes a mounting pipe seat 71, a gas connecting pipe 72, a fixing seat 74, a gas one-way valve 75, an air outlet nozzle 76 and an air inlet flange pipe 77. The mounting pipe seat 71 is mounted on the air inlet flange pipe 77, the gas connecting pipe 72 is mounted on the mounting pipe seat 71 through the fixing seat 74, the gas one-way valve 75 is arranged in the gas connecting pipe 72, and an air outlet nozzle 76 is arranged at the outlet of the gas connecting pipe 72, and the center of the air outlet nozzle 76 corresponds to the center of the core shaft 83. The central axis of the air outlet hole of the air outlet nozzle 76 is coaxial with the axis of the air inlet flange pipe 77, and the coaxiality is less than 0.1mm, which can ensure that the gas can be smoothly dissipated into the water. The gas one-way valve 75 can realize the one-way flow of gas to prevent the liquid in the pipeline from flowing back into the air pipe due to pressure. According to the fluid mechanics analysis of laminar flow around a cylinder, the water velocity in the area near the air outlet nozzle 76 is close to 0, and oxygen can be smoothly dispersed into the water, so that the cutting chamber of the cutter can be evenly aerated. This aeration method is highly efficient and the cutting is uniform. Due to the effect of the fluid, a negative pressure effect is formed in the area near the air outlet nozzle 76. When the air pressure is slightly lower than the water pressure, aeration can be smoothly achieved, which reduces the energy consumption of the equipment.

[0053] A guide cone 81 is provided at the water inlet end of the core shaft 83 , and the guide cone 81 corresponds to the air outlet nozzle 76 .

[0054] The static spiral cutter 8 is composed of thousands of cutting blades 84 that rotate in a variable pitch to form a discrete stepped spiral surface. Water has a certain initial flow velocity (V≥2m / s). When the mixed fluid of water and air passes through the spiral cutter, the large bubbles in the mixed flow are infinitely cut and refined into small bubbles of micro-nano scale in the spiral channel. The small oxygen bubbles of micro-nano scale are continuously pressurized and expanded, and finally burst and dissolved in the water, which greatly increases the dissolved oxygen content in the water.

[0055] The sewage pump 3 is connected to the anoxic zone 15, the sewage pipe 9 is connected to the aerobic zone 13, the internal reflux pump 16 connects the aerobic zone 13 and the anoxic zone 15, one side of the mud outlet of the secondary sedimentation zone 11 discharges mud through the mud discharge valve 12, and the other side is connected to the entrance of the anaerobic zone 17 through the sludge reflux pump 14, and the control system 10 is connected to the sewage pump 3, the sewage inlet pump 1 and the internal reflux pump 16.

[0056] The anaerobic zone 17 and the anoxic zone 15 are provided with stirring blades 2 .

[0057] The A2O domestic sewage treatment method of this embodiment comprises the following steps:

[0058] The sewage passes through the anaerobic zone 17, the anoxic zone 15, the aerobic zone 13 and the secondary sedimentation zone 11 in sequence to obtain clear liquid and sludge. The clear liquid is discharged, part of the sludge is discharged through the sludge discharge valve 12, and part of the sludge is returned to the anaerobic zone 17 through the sludge return pump 14. At the same time,

[0059] The sewage pump 3 sucks sewage from the anoxic zone 15, generates micro-nano bubbles under the action of the axial central aeration mechanism 7 and the static spiral cutter 8, and enters the aerobic zone 13 for aeration.

[0060] The stirring blades 2 are also included to drive the sewage to stir in the anaerobic zone 17 and the anoxic zone 15 .

[0061] The nitrified liquid produced in the aerobic zone 13 flows back to the anoxic zone 15 to form an internal reflux.

[0062] The first anaerobic zone is inflowed with raw sewage and the phosphorus-containing sludge returned from the secondary sedimentation tank. The main function of this pool is to release phosphorus, which increases the concentration of P in the sewage. The dissolved organic matter is absorbed by the microbial cells and the BOD5 concentration in the sewage decreases. In addition, part of NH3-N is removed due to cell synthesis, which reduces the NH3-N concentration in the sewage, but the NO3-N content does not change.

[0063] In the anoxic zone, denitrifying bacteria use organic matter in sewage as a carbon source, reduce a large amount of NO3-N and NO2-N brought into the reflux mixed liquor to N2 and release it into the air. Therefore, the BOD5 concentration decreases, the NO3-N concentration decreases significantly, and the change in phosphorus is very small.

[0064] In the aerobic zone, organic matter is biochemically degraded by microorganisms and continues to decline; organic nitrogen is ammonified and then nitrified, causing a significant decrease in the concentration of NH3-N. However, as the nitrification process increases the concentration of NO3-N, P also decreases at a faster rate due to excessive uptake by polyphosphate bacteria.

[0065] The A2O process can simultaneously complete the removal of organic matter, nitrification and denitrification, and the removal of excessive phosphorus intake. The premise of denitrification is that NO3-N should be completely nitrified. Aerobic tanks can complete this function, while anoxic tanks complete the denitrification function. Anaerobic tanks and aerobic tanks jointly complete the phosphorus removal function.

[0066] A2O is a common domestic sewage treatment process. The aeration method of its aerobic zone usually adopts traditional bottom aeration, and the dissolved oxygen efficiency is low. The novel aeration device of the present invention can cut and refine the large bubbles in the gas-liquid mixed solution into small bubbles of micro-nano scale, which can increase the dissolved oxygen in a shorter time, and the dissolved oxygen amount can be regulated by controlling the gas flow rate.

[0067] When the new aeration device is started, the sewage pump draws sewage from the anoxic zone, and the air compressor works to inject air into the pipeline, so that the sewage and air form a gas-liquid mixed flow in the pipeline. Under certain flow rate conditions, it passes through the static spiral cutter and the internal spiral flow channel. It is subjected to the shear force on the surface of the trapezoidal spiral. At the same time, a strong cyclone field is formed in the flow channel, which produces a Magnus effect, causing changes in the surface tension and viscosity of the liquid, and strengthening the gas-liquid mass transfer process. The gas flow rate is controlled by adjusting the gas flow control valve, and then the HANA brand dissolved oxygen analyzer HI4421 is used to detect the effluent dissolved oxygen concentration (DO) concentration. Then, the gas flow control valve is repeatedly adjusted to make the DO concentration reach the optimal concentration required for the biological activity of sludge in the aerobic zone.

[0068] This embodiment discloses a simulation situation, simulating the process facilities and conditions of a sewage treatment plant. The test adopts an experimental environment such as activated sludge with the same composition. The test system is as follows: Figure 1 The main equipment includes: sewage inlet pump 1, internal return pump 16, sludge return pump 14 (model: DBY-10 electric diaphragm pump, Shanghai Kaili Pump Industry Co., Ltd.); air compressor 3 (model: V-0.17 / 8 air compressor, Jurong Boiler Container Factory); and gas flow control valve 6, gas check valve, etc. The whole system is connected by flange pipes with a specification of DN50. The anaerobic zone, anoxic zone, and aerobic zone all use plastic water tanks with a length, width, and height of 2m. The secondary sedimentation zone uses a volume of about 6m 3The bottom is a funnel-shaped water tank. Among them, the new aeration device is mainly composed of a static spiral cutter, an air compressor, SQB non-negative pressure variable frequency water supply equipment, etc., with a simple structure and easy operation. The aerobic zone adopts the new aeration device of the present invention. In the test, the mixed liquor suspended solid concentration (MLSS) is 3000-3500 mg / L, the sludge return ratio is 75%, the mixed liquor return ratio is 100%, the hydraulic retention time (HRT) of the anoxic zone, anaerobic zone and aerobic zone is 2.5h, 2.5h and 16h respectively, the sludge retention time (SRT) is 20d, the oxygen concentration of the anaerobic zone is 0-0.3mg / L, and the oxygen concentration of the anoxic zone is 0.2-0.5mg / L. The water inlet flow rate of the experiment is controlled at 18L / h, and the air inlet flow rate of the new aeration device and the bottom aeration device is controlled at 0.60L / min. The experimental conditions and sampling intervals of each stage are kept consistent, and three groups of experiments are carried out successively. The changes of the main water quality indicators (SS, COD, NH3-N, TP, turbidity, DO concentration) after the aerobic zone treatment were used as a reference to investigate the improvement effect of the new aeration device on the A2O sewage treatment process. Under the premise of controlling the same experimental conditions, the domestic sewage was treated with the new aeration device and the bottom aeration process. The new aeration device increased the SS concentration removal rate by 12.3% compared with the bottom aeration, the COD removal efficiency was increased by 5.6%, the ammonia nitrogen removal rate was increased by about 8.1%, the maximum TP removal rate was increased by 8.5%, the saturated DO concentration could reach 8.3±0.2mg / L, and the dissolved oxygen capacity was increased by 48.2%. It can be seen that the new aeration device has the advantages of simple structure and good economy, and has a good application prospect in optimizing the A2O domestic sewage treatment process. At the same time, it also solves the problems of uneven dissolved oxygen, easy clogging of aeration holes, and difficult maintenance caused by the bottom aeration used in the traditional A2O domestic sewage treatment process.

[0069] The above is only an embodiment of the present invention, and the common sense such as the known specific structure and characteristics in the scheme is not described in detail here. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the attached claims rather than the above description, so it is intended to include all changes within the meaning and scope of the equivalent elements of the claims. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A novel aeration device, characterized in that: include: A sewage pump (3), an air compressor (4), an air guide pipe (5), a gas flow control valve (6), an axial central gas filling mechanism (7), a static spiral cutter (8) and a sewage pipe (9); one end of the sewage pump (3) is connected to a sewage inlet, and the other end is connected to the sewage pipe (9) through the static spiral cutter (8) to discharge the sewage; the axial central gas filling mechanism (7) is arranged at the front end of the static spiral cutter (8); the axial central gas filling mechanism (7) is connected to the air compressor (4) through the air guide pipe (5); and the gas flow control valve (6) is arranged on the air guide pipe (5).

2. The novel aeration device according to claim 1 is characterized in that: The static spiral cutter (8) comprises a cutting tube (82), a core shaft (83) is arranged at the center of the cutting tube (82), a plurality of cutting blades (84) are arranged on the core shaft (83) and are stacked in sequence. The cutting blades (84) are inserted through a middle hole on the core shaft (83), and adjacent cutting blades (84) are staggered at an angle and arranged axially with variable pitches according to a spiral line equation to form a spatial spiral structure. The surface of the formed spatial spiral structure is in a stepped shape.

3. The novel aeration device according to claim 2 is characterized in that: The pitch of the spatial spiral structure gradually decreases from the water inlet end to the water outlet end.

4. The novel aeration device according to claim 1 or 2, characterized in that: The axial center gas filling mechanism (7) comprises a mounting pipe seat (71), a gas connecting pipe (72), a fixing seat (74), a gas one-way valve (75), a gas outlet nozzle (76) and an inlet flange pipe (77); the mounting pipe seat (71) is mounted on the inlet flange pipe (77); the gas connecting pipe (72) is mounted on the mounting pipe seat (71) via the fixing seat (74); the gas one-way valve (75) is arranged in the gas connecting pipe (72); and a gas outlet nozzle (76) is arranged at the outlet of the gas connecting pipe (72); the center of the gas outlet nozzle (76) corresponds to the center of the core shaft (83).

5. The novel aeration device according to claim 3 is characterized in that: A guide cone (81) is provided at the water inlet end of the core shaft (83), and the guide cone (81) corresponds to the air outlet nozzle (76).

6. An A2O domestic sewage treatment system, using the novel aeration device as claimed in claim 5, characterized in that: The invention comprises a sewage inlet pump (1), an anaerobic zone (17), an anoxic zone (15), an aerobic zone (13), an internal return pump (16), a secondary sedimentation zone (11), a sludge discharge valve (12), a sludge return pump (14) and a control system (10), wherein the anaerobic zone (17), the anoxic zone (15), the aerobic zone (13) and the secondary sedimentation zone (11) are connected in sequence, the sewage inlet pump (1) is used to transport sewage to the anaerobic zone (17), and the sewage pump (3 ) is connected to the anoxic zone (15), the sewage pipe (9) is connected to the aerobic zone (13), the internal reflux pump (16) connects the aerobic zone (13) and the anoxic zone (15), one side of the mud outlet of the secondary sedimentation zone (11) discharges mud through a mud discharge valve (12), and the other side is connected to the entrance of the anaerobic zone (17) through a mud reflux pump (14), and the control system (10) is connected to the sewage pump (3), the sewage inlet pump (1) and the internal reflux pump (16).

7. The A2O domestic sewage treatment system according to claim 6, characterized in that: The anaerobic zone (17) and the anoxic zone (15) are provided with stirring blades (2).

8. An A2O domestic sewage treatment method, based on the A2O domestic sewage treatment system according to claim 7, characterized in that: The following steps are involved: The sewage passes through the anaerobic zone (17), the anoxic zone (15), the aerobic zone (13) and the secondary sedimentation zone (11) in sequence to obtain clear liquid and sludge. The clear liquid is discharged, part of the sludge is discharged through the sludge discharge valve (12), and part of the sludge is returned to the anaerobic zone (17) through the sludge return pump (14); at the same time, The sewage pump (3) sucks sewage from the anoxic zone (15), generates micro-nano bubbles under the action of the axial central aeration mechanism (7) and the static spiral cutter (8), and enters the aerobic zone (13) for aeration.

9. The A2O domestic sewage treatment method according to claim 8, characterized in that: It also includes stirring blades (2) driving the sewage to stir in the anaerobic zone (17) and the anoxic zone (15).

10. The A2O domestic sewage treatment method according to claim 9, characterized in that: The nitrified liquid produced in the aerobic zone (13) flows back to the anoxic zone (15) to form an internal reflux.

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