MBBR sewage treatment method with nanobubble high-efficiency oxygen supply

Abstract

The application discloses a kind of MBBR sewage treatment methods of nano bubble high-efficiency oxygen supply, it is related to sewage treatment technical field.The processing system required by it includes MBBR reaction tank, suspended carrier fluidization system, suspended carrier interception system and nano aeration system, MBBR reaction tank is filled with suspended carrier, suspended carrier interception system includes flat paving type interception screen and effluent interception screen, flat paving type interception screen is located at the bottom of MBBR reaction tank and parallel with bottom surface;Nano aeration system includes nano aerator and nano gas generating device, nano gas generating device is located outside MBBR reaction tank, and is connected with the nano aerator located in MBBR reaction tank, wherein the aeration amount of nano aerator is calculated according to formula.The present application makes full use of the characteristics of biofilm method and the advantages of nano bubble, realizes the energy-saving and efficient decontamination process of synchronization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a MBBR sewage treatment method with high-efficiency oxygen supply of nano-bubbles. BACKGROUND

[0002] Biochemical process is the most core process unit of sewage treatment, which undertakes more than 80% of the task of pollutant removal, and is also the process unit with the largest land occupation and the highest energy consumption in sewage treatment plant. 60% to 80% of the land of the sewage treatment plant is used for the construction of biochemical process, and 50% of the power consumption comes from the biochemical process, so the biochemical process is the key to the sustainable development and energy saving and carbon reduction of the sewage treatment plant. From the perspective of biochemical process, the biofilm method becomes the first choice for the construction and operation of the sewage treatment plant in the new period due to its high-efficiency pollutant removal performance. From the perspective of oxygen supply system of the biochemical core equipment, micro-nano bubbles have a wide application prospect in water treatment due to the slow rising speed, long residence time, high dissolution efficiency, self-oxygenation, negative charge and rich free radicals with strong oxidizing properties. The combination of the two processes not only can improve the oxygen utilization rate and reduce the energy consumption, but also can improve the pollutant removal performance and reduce the land occupation, which is the key to the green and low-carbon transformation of the sewage treatment plant.

[0003] At present, the existing technology related to micro-nano aeration in the field of water treatment has the following research reports:

[0004] CN110143664B discloses a micro-nano aeration BAF treatment device and treatment process, comprising a BAF device, a micro-nano bubble generating device and a backwashing device. The BAF device comprises a sewage inlet pump, a BAF reaction tank, a sewage circulating pump and a basket filter. The micro-nano bubble generating device comprises a micro-nano bubble generating device shell, a nano-scale ceramic membrane tube, a liquid flow meter, a gas rotor flow meter, a gas pressure gauge and a gas control valve. By supplying micro-nano bubbles to the system, the gas utilization rate is improved, COD in the sewage is removed, the removal efficiency is high and the energy consumption is low, and at the same time, the BAF reaction tank surface is not caused to roll over. The main technical problems of the treatment device and treatment process are: ① uneven gas supply. The filter material of the BAF device is fixed, and due to the slow rising speed of the supplied micro-nano bubbles and the blockage of the filter material during the rising process, the distribution resistance of the bubbles is increased, which easily leads to anoxic environment in the upper layer of the filter material, thereby affecting the removal effect; ② biological membrane thickening and complex operation control. The micro-nano bubbles can strengthen the mass transfer process and improve the removal efficiency, so for the BAF process, the biological membrane grows faster than the traditional process, and therefore, in order to control the thickness of the biological membrane, compared with the traditional process, the backwashing frequency is increased, which indirectly increases the complexity of the operation control; ③ whether the energy consumption problem is reduced needs to be verified. The energy consumption of the BAF comes from aeration and backwashing, the nano-aeration mode reduces the energy consumption of aeration, but increases the energy consumption of backwashing, so whether the total energy consumption can be reduced needs to be verified by engineering.

[0005] CN214781329U discloses a micro-nano MBBR small-sized integrated rural domestic sewage treatment equipment, which uses nano-aeration instead of air blower aeration, can effectively reduce equipment noise and does not affect the daily life of surrounding residents; the nano-aeration instead of air blower aeration can effectively improve oxygen utilization efficiency, the dissolution rate of micro-nano bubbles in water is more than 85%, can effectively reduce operation cost, the nano-aeration uses an atomizer instead of a traditional aeration head, compared with the traditional aeration equipment, the aeration head is located in the tank, which reduces installation and maintenance difficulty and maintenance cost; under the same aeration intensity, the nano-aeration machine produces more dissolved oxygen than the ordinary aeration machine, has higher biochemical oxygen demand and ammonia nitrogen removal rate, and improves water quality purification treatment effect. The main technical problems of the treatment device are: the aerobic zone uses nano-aeration, which improves oxygen utilization rate, but K3 filler is simultaneously added to the aerobic zone. According to the knowledge of industry personnel, the K3 filler is a suspended carrier, and the aeration intensity of the nano-aeration cannot maintain the uniform fluidization of the K3 filler, and the non-fluidization of the filler means that the aerobic zone has no decontamination function, which is contradictory to the so-called high oxygen utilization rate.

[0006] Therefore, there are still many problems in the application of micro-nano aeration in the field of water treatment, and the prior art needs to be further improved. SUMMARY

[0007] The application aims to provide a MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, which applies nano bubbles to the MBBR sewage treatment method, and realizes the energy-saving and high-efficiency sewage removal process by optimizing the process conditions and operation parameters.

[0008] In order to achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0009] A MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, sequentially comprising the following steps:

[0010] a. Preparing a required treatment system

[0011] The treatment system comprises an MBBR reaction tank, a suspended carrier fluidization system, a suspended carrier interception system and a nano aeration system, the MBBR reaction tank is filled with suspended carriers, the suspended carrier interception system comprises a flat interception screen and a water outlet interception screen, the suspended carrier fluidization system comprises a stirrer and a perforated aeration pipe in the MBBR reaction tank, the nano aeration system comprises a nano aerator and a nano gas generating device, the nano gas generating device is located outside the MBBR reaction tank and connected with the nano aerator in the MBBR reaction tank, and the flat interception screen is parallel to the bottom surface of the MBBR reaction tank and located above the nano aerator.

[0012] The specific gravity of the suspended carrier is 1.10g / cm 3 ~1.20g / cm 3 , which is a cylindrical suspended carrier with a thickness of 3mm~5mm and a suspended carrier aperture of 4mm~5mm.

[0013] b. The sewage to be treated enters the MBBR reaction tank, the stirrer is started, the influent SS is lower than 50mg / L, and the nano aerator is used to provide nano bubbles into the reaction tank, and the aeration amount of the nano aerator is calculated according to formula (1):

[0014]

[0015] In formula (1), α is the oxygen transfer correction coefficient, E A is the oxygen transfer efficiency of the nano aerator, AOR is the total oxygen demand, Cs' is the saturated dissolved oxygen of the clear water at the actual temperature, Cs is the saturated dissolved oxygen of the sewage to be treated at the actual temperature, and C is the actual DO of the treatment system.

[0016] c. Operation:

[0017] In the conventional operation stage, the power density of the stirrer is 7.5~10W / m 3 , and the aeration amount of the perforated aeration pipe is 2 times the area of the interception screen.

[0018] In the strong hydraulic shear stage, the power density of the agitator is 15-20 W / m 3 , and the aeration amount of the perforated aeration pipe is 4 times the area of the interception screen.

[0019] For the MBBR reaction tank with the core of removing organic matter, the strong hydraulic shear stage is started once every 10-15 days, and each time is opened for 2-3 hours; for the MBBR reaction tank with the core of removing ammonia nitrogen, the strong hydraulic shear stage is started once every 20-25 days, and each time is opened for 1-2 hours.

[0020] The MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, the effluent interception screen is located at the effluent end of the MBBR reaction tank and is perpendicular to the water flow direction.

[0021] The MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, the nano aerator is located between the flat interception screen and the bottom surface of the MBBR reaction tank, and a plurality of nano aerators are uniformly arranged.

[0022] The MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, the pore size of the nano aerator is 100-500 nm, the value of alpha is 0.95, and the value of E A is 0.90%-0.95%.

[0023] The MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, the perforated aeration pipe is located below the bottom of the effluent interception screen by 5-10 cm, and the openings of the holes on the perforated aeration pipe are upward.

[0024] The MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, the agitator is a variable frequency agitator, and the installed power density is 7-20 W / m 3 .

[0025] The specific gravity of the suspended carrier is 1.15 g / cm 3 , and the thickness is 4 mm.

[0026] Compared with the prior art, the present application has the following beneficial technical effects:

[0027] (1) The present application proposes a kind of MBBR sewage treatment method of nano bubble high-efficiency oxygen supply, it applies nano aerator to MBBR sewage treatment, by adjusting the density, thickness, aperture and other parameters of suspended carrier, such as the density of suspended carrier is adjusted to be larger, it is matched with more bubbles generated by nano aerator;Since the mass transfer of nano aerator is good, biological membrane is thick, so the aperture of suspended carrier is adjusted to be larger.Because of the influence of nano aerator to MBBR, such as mass transfer is strong, biological membrane thickening, so strong fluidization flushing is carried out in the running stage, and according to different running stage, heterotrophic bacteria grow faster, and the frequency of decarburization backwashing is higher, and the frequency of backwashing is lower when nitrification grows slowly.

[0028] (2) The present application saves aeration quantity, energy saving and consumption reduction.Nano bubble diameter is smaller, it has larger specific surface area, and the oxygen transfer efficiency of aerator is higher, compared with traditional aeration mode, nano aeration can save more than 75% of aeration quantity, thereby reducing energy consumption.

[0029] (3) The present application has high decontamination efficiency and saves land.Nano bubble stays in water for a long time, can provide sufficient oxygen for microorganisms, biological membrane mass transfer effect is better, treatment efficiency is higher, biochemical reaction time is shorter, compared with traditional activated sludge method, it reduces 70% of land occupation, and further reduces 20% compared with traditional MBBR.

[0030] (4) The present application reduces the energy consumption of suspended carrier fluidization.The oxygen can be uniformly and fully transmitted to sewage to realize high-efficiency utilization by replacing the traditional aeration shear with agitator in the aerobic zone of system, and the fluidization kinetic energy is lower, for example, the fluidization kinetic energy of a certain wastewater treatment plant in north China is reduced by more than 80%.Not only the uniform fluidization of suspended carrier is maintained, but also the oxygen can be uniformly and fully transmitted to sewage to realize high-efficiency utilization.

[0031] (5) The present application has flexible operation control and stable effect.The biological membrane thickness is maintained by flexible regulation of power density in different periods, the problem of biological membrane thickening under high-efficiency mass transfer is effectively avoided, the long-term stable mass transfer and oxygen transfer process of system is guaranteed, and stable operation of system is realized. BRIEF DESCRIPTION OF DRAWINGS

[0032] The present application will be further described below in conjunction with the drawings:

[0033] Figure 1 It is the front view of the treatment system of the present application;

[0034] Figure 2 It is the plan view of the treatment system of the present application;

[0035] Figure 3 It is the running effect diagram of pilot system;

[0036] In the drawings:

[0037] 1, agitator, 2, MBBR reaction tank, 3, nano aerator, 4, perforated aeration pipe, 5, water interception screen, 6, flat interception screen, 7, suspended carrier, 8, nano gas generating device. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0039] It can be understood that the connection relationship described in the present application refers to direct or indirect connection. For example, A is connected with B, which can be that A is directly connected with B, or A is indirectly connected with B through one or more other electrical components. For example, A can be directly connected with C, and C is directly connected with B, so that A is connected with B through C. It can also be understood that "A is connected with B" described in the present application can be that A is directly connected with B, or A is indirectly connected with B through one or more other electrical components.

[0040] The technical concept of the present application is that a moving bed biofilm reactor (MBBR) is used for water treatment biochemical process, the microorganism nature of which is a biofilm, and the hydraulic characteristic of which is fluidization. Compared with the traditional activated sludge method, the biofilm method has stronger enrichment ability for functional bacteria. From the micro level, the relative abundance of functional bacteria is generally more than 10 times that of the activated sludge, but from the macro level, the treatment performance of the biofilm method is only twice that of the activated sludge method. The main reason is that the pollution removal process of the biofilm is mainly based on mass transfer and oxygen transfer. Since the transfer resistance of liquid ions is smaller than that of gas molecules, the transfer rate is higher, so for MBBR, the DO mass transfer essentially restricts the efficient exertion of the pollution removal performance of the biofilm. Therefore, the present application fully utilizes the characteristics of the biofilm method and the advantages of nano bubbles to realize the synchronous energy saving and high-efficiency pollution removal process.

[0041] In combination with Figure 1 and Figure 2 It is shown that the present application is a MBBR sewage treatment method with high-efficiency oxygen supply of nano bubbles, and the required treatment system comprises an MBBR reaction tank 2, a suspended carrier fluidization system, a suspended carrier interception system and a nano aeration system.

[0042] The MBBR reaction tank comprises a tank body, a water inlet and a water outlet, the tank body is internally filled with suspended carriers 7, the suspended carriers are MBBR biofilm fillers, in order to cooperate with the nano aerator, the specific gravity of the suspended carriers is adjusted to 1.10 g / cm 3 ~ 1.20 g / cm 3 , the shape is a cylindrical suspended carrier, the thickness is adjusted to 3 mm ~ 5 mm, and the suspended carrier aperture is adjusted to 4 mm ~ 5 mm.

[0043] The suspended carrier interception system comprises a flat interception screen 6 and an effluent interception screen 5, the flat interception screen is located at the bottom of the MBBR reaction tank and is parallel to the bottom, the suspended carrier is above the flat interception screen, and the nano aerator 3 is below the flat interception screen; the suspended carrier fluidization system comprises a stirrer 1 located in the MBBR reaction tank and a perforated aeration pipe 4, the nano aeration system comprises the nano aerator 3 and a nano gas generating device 8, the nano gas generating device is located outside the MBBR reaction tank and is connected with the nano aerator located in the MBBR reaction tank, and the nano aerator has a pore diameter of 100nm-500nm.

[0044] Preferably, the stirrer is a variable frequency stirrer, and the installed power density is 7-20W / m 3 , and the air volume (m 3 / h) of the perforated aeration pipe is 2-4 times the area (S) of the effluent interception screen.

[0045] The operation method of the system is described below.

[0046] Step one, the wastewater to be treated enters the MBBR reaction tank, the stirrer is started, the SS of the influent is less than 50mg / L, and the nano bubbles are provided to the MBBR reaction tank through the nano aerator; the aeration amount of the nano aerator is calculated according to formula (1):

[0047]

[0048] In formula (1), α is the oxygen transfer correction coefficient, E A is the oxygen transfer efficiency of the nano aerator, AOR is the total oxygen demand, Cs' is the saturated dissolved oxygen of the clean water at the actual temperature, Cs is the saturated dissolved oxygen of the wastewater to be treated at the actual temperature, and C is the actual DO of the treatment system.

[0049] Step two, operation:

[0050] In the conventional operation stage, the power density of the stirrer is 7.5-10W / m 3 , and the aeration amount of the perforated aeration pipe is 2 times the area of the interception screen.

[0051] In the strong hydraulic shear stage, the power density of the stirrer is 15-20W / m 3 , and the aeration amount of the perforated aeration pipe is 4 times the area of the interception screen.

[0052] For the MBBR reaction tank taking the removal of organic matter as the core, the strong hydraulic shear stage is started once every 10-15 days, and each time is started for 2-3h; for the MBBR reaction tank taking the removal of ammonia nitrogen as the core, the strong hydraulic shear stage is started once every 20-25 days, and each time is started for 1-2h.

[0053] The present invention will be further described below with reference to specific embodiments.

[0054] Example 1:

[0055] A wastewater treatment plant in northern China has a designed capacity of 10,000 m³. 3 / d, treating municipal wastewater, using an AO process system based on MBBR, with a total retention time of 10 hours, including 5 hours each for aerobic and anoxic zones. The aerobic zone uses traditional blower aeration, with air supply based on influent and effluent quality requirements. The anoxic zone uses agitators. The air requirement for the aerobic zone is designed based on the influent water quality, and the agitator installation power density for the anoxic zone is 10W / m³. 3 Long-term energy consumption is shown as zero based on testing. In actual operation, the aerobic zone aeration rate is 0.387 kWh / m³. 3 Stirring in the anoxic zone at 0.050 kWh / m 3 The energy consumption in the hypoxic zone is 13% of that in the aerobic zone.

[0056] Table 1 Energy consumption for different fluidization kinetic energies

[0057] Serial number Function area Fluidization power of suspended carrier Power consumption per ton of water 1 Oxygen Aeration 0.387 2 Anoxia Stirring 0.050

[0058] As can be seen from Example 1, the energy consumption of agitator in suspension fluidization is lower than that of aeration.

[0059] Example 2:

[0060] The effects of different aeration methods on the nitrification performance of MBBR and activated sludge processes were investigated. The experimental water was taken from the influent of the aerobic tank of a wastewater treatment plant's MBBR system, with a COD below 50 mg / L. The activated sludge was taken from the end of the aerobic tank, and the suspended carrier was also taken from the aerobic tank. An SBR (Simplified Bioreactor) system was used, with a 50 L MBBR reactor volume and a controlled temperature of 20℃. The activated sludge concentration was controlled at 4000 mg / L, and the MBBR system's filling rate was controlled at 50%. Agitators were installed to promote fluidization, and nano-aeration was provided to the system. Ammonia nitrogen levels were periodically sampled and monitored until they fell below 1.5 mg / L, at which point the reaction was stopped, and the nitrification load was calculated. The results are shown in Figure 0.

[0061] From 0 can be seen, under the premise of equal aeration, for activated sludge system, using micro-porous aeration than perforated pipe aeration has a certain promotion, but further using nano-aeration, nitrification performance has no obvious promotion, the main reason is that the functional bacteria in activated sludge system load promotion limiting factor is the amount, not oxygen. For biofilm system, using perforated pipe aeration and micro-porous aeration when the nitrification performance is basically the same, and significantly higher than activated sludge system, on the one hand, the reason is that the biofilm on the efficient enrichment of functional bacteria, higher processing efficiency; On the other hand, due to the cutting of suspended carrier in the fluidization process, so even if the perforated pipe aeration provides large aperture bubble, will be due to the cutting of suspended carrier small, so the perforated pipe aeration and micro-porous aeration under the system nitrification load is basically the same. And further using nano-aeration, nitrification performance has been significantly improved, is 1.54 times of micro-porous aeration. The main reason is that the smaller bubbles improve the oxygen utilization rate, promote the mass transfer of DO, stimulate the activity of the inner layer of biofilm functional bacteria, thus improving the nitrification load.

[0062] Table 2 Influence of different aeration modes on activated sludge and biofilm performance

[0063]

[0064]

[0065] Example 3

[0066] In order to verify the influence of influent SS on nano-aeration, the test was verified by comparison. The effective tank capacity of the test system was 5m 3 , the influent was the influent of the aerobic tank of a municipal wastewater treatment plant in the north, the SS was controlled at 30mg / L, 50mg / L, 80mg / L and 100mg / L, the system was subjected to aerobic reaction, the same air volume was input, and the nano-aerator was connected with a pressure gauge at one end. The system was operated continuously for 6 months.

[0067] The pressure gauges of each reactor showed a stable pressure of 2.10-2.15 MPa during the operation when the SS was controlled at 30 mg / L and 50 mg / L. When the SS was increased to 80 mg / L, the pressure gauge showed a continuous increase from the 159th day. After 6 months of operation, the final pressure was 2.18 MPa. When the SS was increased to 100 mg / L, the pressure increased from the 135th day, and the final pressure was 2.22 MPa. The increase in pressure was mainly due to the blockage of the nano-aerator aperture by SS particles, thereby increasing the aeration resistance. From the test process, the time was relatively short compared to the engineering operation, but from the results, when the SS was greater than 80 mg / L, the test system showed an impact on the nano-aerator during operation. Therefore, the actual control should ensure that the SS of the system is below 50 mg / L.

[0068] Example 4:

[0069] Through the test, the influence of the specific gravity, aperture, and thickness of the suspended carrier on the performance of the nano-aeration was determined.

[0070] (1) First, the specific gravity of the suspended carrier. Four specifications of the suspended carrier with a specific gravity of 0.96 g / cm 3 , 1.05 g / cm 3 , 1.15 g / cm 3 , and 1.25 g / cm 3 were selected. All of them were cylindrical suspended carriers with a diameter of 25 mm, a thickness of 10 mm, and an aperture of 5-6 mm. The test water was the influent of the aerobic tank of a municipal wastewater treatment plant in the north, with SS below 50 mg / L, ammonia nitrogen of 40 mg / L, effective tank capacity of 500 L for the MBBR reactor, filling rate of 50%, continuous flow operation, and the same aeration amount and stirring power to ensure oxygen supply and suspended carrier fluidization. The test was operated for one month, and the test results are shown in Table 1. As can be seen from Table 1, the influence of the specific gravity of the suspended carrier on the test system is mainly in the fluidization, which indirectly affects the biofilm and treatment effect. The better the fluidization, the more uniform the distribution of the suspended carrier, the better the biofilm, and the higher the treatment performance. For the nano-aeration system, nano-bubbles will adhere to the suspended carrier during the rising process, thereby increasing the buoyancy of the suspended carrier, which is equivalent to reducing the specific gravity. Therefore, the suspended carrier with a specific gravity of 1.15 g / cm 3 is suitable for the nano-aeration system.

[0071] Table 3 Influence of the specific gravity of the suspended carrier on the treatment performance of the system

[0072]

[0073] (2) Secondly, the research on the aperture of the suspended carrier. The test selected three specifications of average aperture of 3.5 mm, 4.5 mm and 5.5 mm, the suspended carrier diameter was 25 mm, the thickness was 5 mm, and the specific gravity was 1.15 g / cm 3 . The test water was the influent of the aerobic tank of a municipal wastewater treatment plant in the north, the SS was controlled to be less than 50 mg / L, the ammonia nitrogen was 40 mg / L, the effective tank capacity of the reaction tank was 500 L, the filling rate was 50%, the continuous flow operation was carried out, the same aeration amount and stirring power were controlled to ensure oxygen supply and suspended carrier fluidization, and the test was operated for one month. The test results are shown in Table 1. The MBBR biofilm is on the membrane, the biofilm is attached to the protected area inside the suspended carrier, the biofilm is thicker than the traditional way due to the good mass transfer of the nano-bubbles, so the actual aperture is smaller, the surface tension is larger, and the mass transfer resistance inside the aperture is higher; on the contrary, the larger the aperture, the smaller the effective specific surface area, although the large aperture can ensure the mass transfer process, but the overall treatment performance of the system is low. As can be seen from Table 1, when the aperture is 4.5 mm, the treatment performance is optimal.

[0074] Table 4 Influence of the aperture of the suspended carrier on the treatment performance of the system

[0075] Serial number Suspended carrier aperture / mm Nitration load / kg m -3 ·d -1 ]]> 1 5.5 0.327 2 4.5 0.449 3 3.5 0.357

[0076] (3) Finally, the research on the thickness of the suspended carrier, the test selected three thicknesses of 10 mm, 4 mm and 2 mm of the suspended carrier, the specific gravity was 1.15 g / cm 3 , the diameter was 25 mm, and the average aperture was 4.5 mm. The test water was the influent of the aerobic tank of a municipal wastewater treatment plant in the north, the SS was controlled to be less than 50 mg / L, the ammonia nitrogen was 40 mg / L, the effective tank capacity of the reaction tank was 500 L, the filling rate was 50%, the continuous flow operation was carried out, the same aeration amount and stirring power were controlled to ensure oxygen supply and suspended carrier fluidization, and the test results are shown in Table 5. The thinner the suspended carrier, the shorter the mass transfer distance in the aperture, and the better the mass transfer effect. However, as the suspended carrier becomes thinner, the fluidization form in the water becomes single and regular, which further limits the mass transfer process. As can be seen from Table 5, when the thickness of the suspended carrier is 4 mm, the nitrification performance is 1.1 times that of the suspended carrier with a thickness of 10 mm, and when the suspended carrier becomes 2 mm, due to the limitation of the fluidization process, the treatment load is only 82% of the suspended carrier with a thickness of 4 mm, so the thickness of 4 mm is the best parameter.

[0077] Table 5 Influence of the thickness of the suspended carrier on the treatment performance of the system

[0078]

[0079] Example 5:

[0080] The pilot project is located in a municipal wastewater treatment plant in the north, using AO process, the reaction tank capacity is 10 m 3 , install two agitator, control the agitator power density is 7.5 ~ 20 W / m 3 , MBBR reaction tank filled with suspended carrier, carrier specific gravity 1.15 g / cm 3 , aperture 4.5 mm, thickness 4 mm, filling rate 50%, the influent is the project of the oxygen tank, control SS less than 50 mg / L, ammonia nitrogen 40 mg / L. Using continuous flow operation, observation of biofilm thickness and the system nitrification performance, running effect as shown in Figure 3 .

[0081] The initial operation, control the agitator power density is 8 W / m 3 , the suspended carrier fluidization normal, the system runs normally, effluent quality is stable, the aerobic zone biofilm thickness in 400 ~ 500 μm. Run to the 20th day, the detection system effluent ammonia nitrogen has fluctuation, and there is a rising trend, after continuous 5 days of detection, confirm the system effluent ammonia nitrogen continues to rise, through the detection of biofilm, found that the biofilm thickness increased to 750 ~ 800 μm, the mass transfer difference affects the treatment load. Using the way of improving the agitator power density, strengthen the suspended carrier fluidization, promote the biofilm shedding, reduce the biofilm thickness. The 26th day, the agitator power density is increased to 14 W / m 3 , running 1 h, the naked eye can see the fluidization is intense, but the nitrification performance has not improved, the detection of system effluent SS also has no obvious improvement. The 28th day, the agitator power density is increased to 19 W / m 3 , running 1 h, the suspended carrier fluidization is more intense, the detection of system effluent SS also has obvious improvement. 1 h later, the detection of biofilm thickness, has basically restored to 500 ~ 600 μm level, the effluent ammonia nitrogen also slowly reduced, to the 30th day, restore to the initial level.

[0082] Example 6:

[0083] The effluent of a municipal wastewater treatment plant in the north executes GB18918-2002 level A standard. The first phase uses AAO process based on activated sludge method, the treatment scale is 4 × 10 4 m 3 / d, using micro-porous aeration method; the second phase uses AOAO process based on MBBR, the treatment scale is 1 × 10 4 m 3 / d, using perforated pipe aeration method; the third phase uses AOA process based on MBBR, the treatment scale is 2 × 10 4 m 3 / d, the design and operation effect of each period is shown in Table 1. From the table, it can be seen that the combination of MBBR and nano-aeration not only reduces the operation energy consumption, but also improves the treatment performance. Compared with the traditional activated sludge + micro-porous aeration mode, the energy consumption is reduced by 55%, and the land occupation is reduced by 73%. Further compared with the MBBR + perforated aeration mode, the land occupation is saved by 30%.

[0084] Table 6 Application effect of different processes combined with aeration modes

[0085] Comparative project Unit Activated sludge + micro-porous aeration MBBR + perforated aeration MBBR + nano-aeration Treatment scale km 3 / d]]> 4 1 2 Oxygen section residence time h 13 5 3.5 Effluent ammonia nitrogen concentration mg / L <1.5 <1.5 <1.5 Oxygen area power consumption kWh / m 3 ]]> 0.332 0.337 0.150 Impact resistance - Poor General Excellent

[0086] The parts not mentioned in the present application can be realized by referring to the prior art.

[0087] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not used as a limitation on the present application, and as long as the above embodiments are appropriately changed and changed within the scope of the spirit of the present application, they should fall within the scope of protection of the claims of the present application.

Claims

1. A MBBR sewage treatment method of nanobubble high-efficiency oxygen supply, characterized in that, Comprise the following steps in turn: a. Prepare the required treatment system The treatment system comprises a MBBR reaction tank, a suspended carrier fluidization system, a suspended carrier interception system and a nano-aeration system. The MBBR reaction tank is filled with suspended carriers. The suspended carrier interception system comprises a flat interception screen and a water outlet interception screen. The suspended carrier fluidization system comprises a stirrer and a perforated aeration pipe in the MBBR reaction tank. The nano-aeration system comprises a nano-aerator and a nano-gas generating device. The nano-gas generating device is located outside the MBBR reaction tank and is connected to the nano-aerator in the MBBR reaction tank. The flat interception screen is parallel to the bottom surface of the MBBR reaction tank and is located above the nano-aerator. The specific gravity of the suspension carrier is 1.10g / cm 3 ~1.20g / cm 3 The suspension carrier is cylindrical with a thickness of 3mm~5mm and a hole diameter of 4mm~5mm. b. The wastewater to be treated enters the MBBR reaction tank, the stirrer is started, the SS of the influent is less than 50 mg / L, and nano-bubbles are provided to the MBBR reaction tank by the nano-aerator. The aeration amount of the nano-aerator is calculated according to formula (1): In formula (1), α is the oxygen mass transfer correction coefficient, E A is the oxygen transfer efficiency of the nano aerator, AOR is the total oxygen demand, Cs' is the saturated dissolved oxygen of clean water at the actual temperature, Cs is the saturated dissolved oxygen of the wastewater to be treated at the actual temperature, and C is the actual DO of the treatment system. c. Operation: In the normal operation stage, the power density of the stirrer is 7.5-10 W / m 3 , and the aeration amount of the perforated aeration pipe is 2 times the area of the interception screen. The power density of the stirrer is 15-20 W / m3 in the strong hydrodynamic shear stage 3 The aeration amount of the perforated aeration pipe is 4 times the area of the interception screen. For the MBBR reaction tank focusing on removing organic matter, a strong hydraulic shear stage is started every 10-15 days, and each time the stirrer is started for 2-3 hours. For the MBBR reaction tank focusing on removing ammonia nitrogen, a strong hydraulic shear stage is started every 20-25 days, and each time the stirrer is started for 1-2 hours.

2. The MBBR wastewater treatment method with high-efficiency oxygen supply of nano bubbles according to claim 1, characterized in that: The water outlet interception screen is located at the water outlet end of the MBBR reaction tank and is perpendicular to the water flow direction.

3. The MBBR wastewater treatment method with high-efficiency oxygen supply of nano bubbles according to claim 1, characterized in that: The nano-aerator is located between the flat interception screen and the bottom surface of the MBBR reaction tank and is evenly spaced.

4. The MBBR wastewater treatment method of claim 3, wherein the method comprises: The pore diameter of the nano-aerator is 100-500 nm, the value of α is 0.95, and the value of E A The value of α is 0.90%-0.95%.

5. The MBBR wastewater treatment method of Claim 1, wherein the method is characterized by: The stirrer is a variable frequency stirrer, and the installed power density is 7-20 W / m 3 . 6.The MBBR wastewater treatment method with high-efficiency oxygen supply of nano bubbles according to claim 1, characterized in that: The specific gravity of the suspension carrier is 1.15 g / cm 3 , and the thickness is 4 mm.

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