High-efficiency denitrification system, method and application based on two-stage MABR

Abstract

The application belongs to the technical field of sewage treatment, and discloses a high-efficiency denitrification system, method and application based on two-stage MABR, which comprises a MABR-PN / DN reactor, a MABR-PN / A reactor, a peristaltic pump, an aeration hollow fiber membrane assembly, a carrier, an aeration pump, a gas flow meter, a pressure gauge, a liquid flow meter, and the MABR-PN / DN reactor and the MABR-PN / A reactor are arranged along the vertical direction. The system utilizes the series connection design of the MABR-PN / DN and the MABR-PN / A, reduces the adverse effect of organic matters in sewage on the treatment of high-concentration ammonia-nitrogen wastewater by anaerobic ammonia oxidation, and realizes denitrification by returning the nitrate nitrogen generated by the MABR-PN / A to the first-stage MABR-PN / DN, breaks through the denitrification limitation of single reactor and single denitrification path, and the overall total nitrogen removal rate of the system is higher than 90%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and in particular relates to a high-efficiency denitrification system, method and application based on two-stage MABR. BACKGROUND

[0002] Membrane aerated biofilm reactor (MABR) is a new membrane wastewater treatment process, which utilizes hydrophobic hollow fiber membranes to transfer oxygen to the wastewater treatment system, and at the same time, the biological membrane formed on the surface of the hollow fiber membrane degrades the pollutants in the wastewater. Membrane aeration can release fine bubbles or even achieve aeration without bubbles, and the oxygen utilization rate is high, which can effectively reduce the aeration energy consumption of the wastewater treatment process. Since oxygen is transferred from the membrane to the solution, the biological membrane can realize the layered structure of the inner and outer aerobic and anoxic zones, and the inner and outer aerobic and anoxic zones are beneficial to the growth of nitrosation / nitrification bacteria and denitrifying bacteria, respectively, which can realize integrated nitrification and denitrification. The patent disclosure of Chinese patent CN119118362A points out that the electron donor and acceptor in the biological membrane of MABR have the characteristics of "reverse diffusion", so it is easy to control the nitrosation reaction, and it is feasible to combine it with anaerobic ammonia oxidation reaction.

[0003] At present, there are studies combining MABR with anaerobic ammonia oxidation to achieve efficient denitrification of low-carbon and nitrogen-containing ammonia nitrogen wastewater. However, in a single MABR unit, the PN / A process effluent contains nitrate nitrogen, making it difficult to break through 90% of the total nitrogen removal rate; when denitrifying bacteria and anaerobic ammonia oxidation bacteria coexist, organic matter is not only a necessary carbon source for the denitrification process, but also inhibits the activity of anaerobic ammonia oxidation bacteria, and the two are difficult to effectively coordinate. The existing MABR system mostly adopts single-stage design or multi-stage series design with a single denitrification mechanism, and has not fundamentally solved the limitations of a single denitrification mechanism and the contradiction between denitrification and anaerobic ammonia oxidation mechanisms in terms of carbon source demand.

[0004] Increasing the number of pool bodies can improve the denitrification effect, but it does not realize the deep coupling of different denitrification paths (such as PN / DN and PN / A). The contradiction between carbon source balance and dissolved oxygen in the denitrification system still exists.

[0005] The purpose of the present application is to reduce the inhibition of carbon source on anaerobic ammonia oxidation and further remove nitrate nitrogen produced by anaerobic ammonia oxidation, and to connect reactors mainly based on short-cut nitrification and denitrification and reactors mainly based on short-cut nitrification and anaerobic ammonia oxidation in series and set backflow, so that the total nitrogen removal rate is higher than 90%. SUMMARY

[0006] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a high-efficiency denitrification system, method and application based on two-stage MABR.

[0007] The technical scheme adopted by the present application to solve its technical problems is:

[0008] An efficient denitrification system based on two-stage MABR, the system comprises a first-stage MABR reactor, i.e., a MABR-PN / DN reactor, a second-stage MABR reactor, i.e., a MABR-PN / A reactor, a first peristaltic pump, a second peristaltic pump, a third peristaltic pump, a fourth peristaltic pump, a fifth peristaltic pump, a first aeration hollow fiber membrane assembly, a second aeration hollow fiber membrane assembly, a first carrier, a second carrier, a first aeration pump, a second aeration pump, a first gas flow meter, a second gas flow meter, a first pressure gauge, a second pressure gauge, a first liquid flow meter, and a second liquid flow meter, and the MABR-PN / DN reactor and the MABR-PN / A reactor are arranged in a vertical direction.

[0009] The substances in the MABR-PN / DN reactor flow into the MABR-PN / A reactor through the second peristaltic pump and the first liquid flow meter, the substances in the MABR-PN / A reactor return to the MABR-PN / DN reactor through the fourth peristaltic pump and the second liquid flow meter to form a loop, the substances in the MABR-PN / DN reactor return to the MABR-PN / DN reactor through the first peristaltic pump, the substances in the MABR-PN / A reactor return to the MABR-PN / A reactor through the third peristaltic pump, the output substances in the MABR-PN / A reactor are discharged through the fifth peristaltic pump, the first aeration hollow fiber membrane assembly and the first carrier are used to filter the substances in the MABR-PN / DN reactor, the second aeration hollow fiber membrane assembly and the second carrier are used to filter the substances in the MABR-PN / A reactor, the first aeration pump, the first gas flow meter, and the first pressure gauge are used to detect the parameters of the MABR-PN / DN reactor, and the second aeration pump, the second gas flow meter, and the second pressure gauge are used to detect the parameters of the MABR-PN / A reactor.

[0010] Further, the MABR-PN / DN reactor is in a sealed shape with an internal hollow, a first lower gas inlet is arranged in close communication with the bottom of the MABR-PN / DN reactor, a first upper gas outlet is arranged in close communication with the top of the MABR-PN / DN reactor, gas can pass into the first aeration hollow fiber membrane assembly in the MABR-PN / DN reactor through the first lower gas inlet, and be discharged out of the MABR-PN / DN reactor through the first upper gas outlet, a first water inlet, a first upper internal reflux port and a first external reflux port are arranged in connection with the upper part of the MABR-PN / DN reactor, a first lower internal reflux port and a first water outlet are arranged in connection with the lower part of the MABR-PN / DN reactor, the first upper internal reflux port and the first lower internal reflux port are arranged in communication through a first peristaltic pump, the first aeration hollow fiber membrane assembly is installed inside the MABR-PN / DN reactor, the first aeration hollow fiber membrane assembly includes a gas inlet and a gas outlet, the gas inlet of the first aeration hollow fiber membrane assembly is arranged in close communication with the first lower gas inlet, and the gas outlet of the first aeration hollow fiber membrane assembly is arranged in close communication with the first upper gas outlet, the first aeration hollow fiber membrane assembly inside the MABR-PN / DN reactor is filled with a first carrier for fixing denitrifying bacteria, the first water inlet can pass in the sewage to be treated, and the sewage to be treated flows into the MABR-PN / DN reactor from the first water inlet and flows out of the reactor from the first water outlet;

[0011] The bottom of the MABR-PN / A reactor is provided with a second lower gas inlet, and the top of the MABR-PN / A reactor is provided with a second upper gas outlet; the upper part of the MABR-PN / A reactor is provided with a second water inlet and a second upper internal reflux port, and the lower part of the MABR-PN / A reactor is provided with a second lower internal reflux port, a second external reflux port and a second water outlet, the second upper internal reflux port and the second lower internal reflux port are arranged in communication through a third peristaltic pump, the second aeration hollow fiber membrane assembly is installed in the hollow interior of the MABR-PN / A reactor, the second aeration hollow fiber membrane assembly includes a gas inlet and a gas outlet, the gas inlet of the second aeration hollow fiber membrane assembly is arranged in close communication with the second lower gas inlet, and the gas outlet of the second aeration hollow fiber membrane assembly is arranged in close communication with the second upper gas outlet, the second aeration hollow fiber membrane assembly inside the MABR-PN / A reactor is filled with a second carrier for fixing anaerobic ammonia oxidation bacteria, and the second water outlet is arranged in communication with a fifth peristaltic pump to discharge the treated water out of the reactor;

[0012] The first lower gas inlet of the MABR-PN / DN reactor is further arranged in connection with a first aeration pump, a first gas flow meter and a first pressure gauge, the first gas flow meter is used to monitor the aeration amount, and the first pressure gauge is used to monitor the aeration pressure;

[0013] The second lower gas inlet under the MABR-PN / A reactor is also connected with a second aeration pump, a second gas flow meter and a second pressure gauge, the second gas flow meter is used for monitoring the aeration amount, and the second pressure is used for monitoring the aeration pressure;

[0014] The first water outlet of the MABR-PN / DN reactor is connected with the second water inlet of the MABR-PN / A reactor through a second peristaltic pump and a first liquid flow meter, and the second outer reflux port of the MABR-PN / A reactor is connected with the first outer reflux port through a fourth peristaltic pump and a second liquid flow meter, so as to realize reflux liquid flow control.

[0015] Further, the first aeration hollow fiber membrane assembly and the second aeration hollow fiber membrane assembly are microporous hollow fiber aeration membranes or non-porous hollow fiber aeration membranes.

[0016] Further, the material of the microporous hollow fiber aeration membrane is PVDF or PTFE or PE, and the membrane pore size is 0.01-0.2 μm; the material of the non-porous hollow fiber aeration membrane is non-porous silicone rubber.

[0017] Further, the carrier is a sponge filler or a combined filler or an elastic filler.

[0018] An efficient denitrification method using the two-stage MABR-based efficient denitrification system as described above, comprising the following steps:

[0019] 1) Start-up phase

[0020] The first carrier is not arranged in the MABR-PN / DN reactor, the first-stage MABR reactor, i.e., the MABR-PN / DN reactor, is inoculated with nitrifying sludge, the sludge concentration MLSS is 3000-5000 mg / L, NH4Cl is introduced, the solution NH4 + -N concentration is 100 mg / L, NaHCO3 is used to adjust the pH to 7.5-8.0, the dissolved oxygen is controlled to be 1.0-1.2 mg / L, the hydraulic retention time is controlled by adjusting the influent flow, and the reactor dissolved oxygen is controlled by adjusting the aeration pressure, until the nitrite accumulation rate in the reactor effluent is higher than 90%, and obvious biofilm is formed on the membrane surface, the sludge-water mixture is poured out, and denitrifying sludge is inoculated, the sludge concentration MLSS is 3000-5000 mg / L, and the first carrier of the MABR-PN / DN reactor is added at the same time, the filling rate is 15-45%, NH4Cl and glucose are introduced, the solution NH4 + -N concentration is 100 mg / L, COD is 200 mg / L, NaHCO3 is used to adjust the pH to 7.5-8.0, the dissolved oxygen is controlled to be 0.3-0.5 mg / L, and the total nitrogen removal rate is >50% when the start-up is considered to be successful;

[0021] The MABR-PN / A reactor does not use a second carrier. The second-stage MABR reactor, i.e., the MABR-PN / A reactor, is inoculated with nitrifying sludge at a MLSS concentration of 3000-5000 mg / L. NH4Cl is then introduced to increase the NH4 content of the solution. + The nitrogen (N) concentration is 100 mg / L. The pH is adjusted to 7.5–8.0 with NaHCO3, and the dissolved oxygen is controlled at 1.0–1.2 mg / L. The hydraulic retention time is controlled by adjusting the influent flow rate, and the dissolved oxygen in the reactor is controlled by adjusting the aeration pressure. The reactor is operated until the nitrite accumulation rate in the effluent exceeds 90%, and a significant biofilm forms on the membrane surface. The mud-water mixture is then poured out, and anaerobic ammonia-oxidizing bacteria with a VSS of 4000–5000 mg / L are inoculated. Simultaneously, the second carrier of the MABR-PN / A reactor is added, with a filling rate of 15–45%. NH4Cl is then introduced to increase the NH4+ concentration in the solution. + Start-up was completed when the TN removal rate was >80% for 10 consecutive days, with a TN concentration of 100 mg / L, dissolved oxygen <0.2 mg / L, temperature 30-35℃.

[0022] 2) Operational Phase

[0023] The first-stage MABR reactor, namely the MABR-PN / DN reactor, controls the dissolved oxygen at 0.3~0.5 mg / L, the hydraulic retention time at 5~10 h, and the temperature at 15~35℃.

[0024] The second-stage MABR reactor, namely the MABR-PN / A reactor, controls dissolved oxygen to <0.2 mg / L, with the same hydraulic retention time as the first-stage MABR reactor, and a temperature of 30-35℃. Every 5-15 days, a trace amount of hydroxylamine with a final concentration of 0.5 mg / L is added to promote the activity of anaerobic ammonia oxidizing bacteria.

[0025] Connect the first-stage MABR reactor and the second-stage MABR reactor, and adjust the reflux ratio to 50~150%.

[0026] Furthermore, in step 2), the mass ratio of ammonia nitrogen to nitrite nitrogen in the effluent of the first-stage MABR reactor is greater than 1:1.32.

[0027] The application of the efficient denitrification method described above in the treatment of ammonia nitrogen-containing wastewater with a low carbon-to-nitrogen ratio.

[0028] The application of the high-efficiency denitrification system based on a two-stage MABR, as described above, in the treatment of ammonia nitrogen-containing wastewater with a low carbon-to-nitrogen ratio.

[0029] The advantages and positive effects of this invention are as follows:

[0030] 1、The system utilizes the series design of MABR-PN / DN and MABR-PN / A, reduces the adverse effect of organic matter in wastewater on the treatment of high-concentration ammonia-nitrogen wastewater by anaerobic ammonia oxidation, and returns the nitrate nitrogen generated by MABR-PN / A to the first-stage MABR-PN / DN to realize denitrification, breaks through the denitrification limitation of single reactor and single denitrification path, and the overall total nitrogen removal rate of the system is higher than 90%.

[0031] 2、The system utilizes the layered structure of the aerobic zone and the anoxic zone of the biofilm on the aeration membrane from inside to outside to realize short-cut nitrification / denitrification and short-cut nitrification / anaerobic ammonia oxidation, realizes directional enrichment of bacterial flora, makes aerobic microorganisms and anaerobic microorganisms exist in the same reactor, coordinates between substrates and products, improves the treatment efficiency, and reduces the device area.

[0032] 3、The system utilizes the characteristics of high oxygen utilization rate of the aeration membrane in the MABR and precise control of the aeration amount, realizes short-cut nitrification control, and the nitrite accumulation rate of the MABR is more than 90%.

[0033] 4、In the method, the first-stage MABR reactor removes the nitrate nitrogen in the reflux liquid and the nitrite nitrogen produced by short-cut nitrification of ammonia-nitrogen in the influent, at the same time, removes a small amount of organic matter in the influent, reduces the adverse effect of organic matter on the second-stage anaerobic ammonia oxidation bacteria. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a structure connection schematic diagram of the high-efficiency denitrification reactor based on two-stage MABR in the application.

[0035] The drawing comprises the following components: 1-1, MABR-PN / DN reactor; 1-2, MABR-PN / A reactor; 2-1, first water inlet; 2-2, first water outlet; 2-3, first upper internal reflux port; 2-4, first lower internal reflux port; 2-5, first external reflux port; 2-6, second water inlet; 2-7, second water outlet; 2-8, second upper internal reflux port; 2-9, second lower internal reflux port; 2-10, second external reflux port; 3-1, first peristaltic pump; 3-2, second peristaltic pump; 3-3, third peristaltic pump; 3-4, fourth peristaltic pump; 3-5, fifth peristaltic pump; 4-1, first aeration hollow fiber membrane assembly; 4-2, second aeration hollow fiber membrane assembly; 5-1, first carrier; 5-2, second carrier; 6-1, first pressure gauge; 6-2, second pressure gauge; 7-1, first gas flow meter; 7-2, second gas flow meter; 8-1, first aeration pump; 8-2, second aeration pump; 9-1, first lower air inlet; 9-2, first upper air outlet; 9-3, second lower air inlet; 9-4, second upper air outlet; 10-1, first liquid flow meter; 10-2, second liquid flow meter. DETAILED DESCRIPTION

[0036] The application will be further described in conjunction with specific examples. The following examples are only descriptive and not limiting, and cannot limit the protection scope of the application.

[0037] The raw materials used in the application are all conventional commercially available products, the methods used in the application are all conventional methods in the art, and the quality of each substance used in the application is conventional quality. The structures and connection relationships not described in detail in the application can be understood as conventional technical means in the art.

[0038] A high-efficiency denitrification system based on two-stage MABR, as shown in Figure 1 The system includes a first-stage MABR reactor, i.e., a MABR-PN / DN reactor 1-1, a second-stage MABR reactor, i.e., a MABR-PN / A reactor 1-2, a first peristaltic pump 3-1, a second peristaltic pump 3-2, a third peristaltic pump 3-3, a fourth peristaltic pump 3-4, a fifth peristaltic pump 3-5, a first aerated hollow fiber membrane module 4-1, a second aerated hollow fiber membrane module 4-2, a first carrier 5-1, a second carrier 5-2, a first aerated pump 8-1, a second aerated pump 8-2, a first gas flow meter 7-1, a second gas flow meter 7-2, a first pressure gauge 6-1, a second pressure gauge 6-2, a first liquid flow meter 10-1, and a second liquid flow meter 10-2, and the MABR-PN / DN reactor and the MABR-PN / A reactor are both arranged in a vertical direction.

[0039] The MABR-PN / DN reactor 1-1 is in a sealed shape with an internal cavity, a first lower gas inlet 9-1 is arranged in close communication with the bottom of the MABR-PN / DN reactor 1-1, a first upper gas outlet 9-2 is arranged in close communication with the top of the MABR-PN / DN reactor 1-1, gas can pass through the first lower gas inlet 9-1 into the first aeration hollow fiber membrane assembly 4-1 in the MABR-PN / DN reactor 1-1, and be discharged out of the MABR-PN / DN reactor 1-1 through the first upper gas outlet 9-2, a first water inlet 2-1, a first upper internal reflux port 2-3 and a first external reflux port 2-5 are arranged in connection with the upper part of the MABR-PN / DN reactor 1-1, a first lower internal reflux port 2-4 and a first water outlet 2-2 are arranged in connection with the lower part of the MABR-PN / DN reactor 1-1, the first upper internal reflux port 2-3 and the first lower internal reflux port 2-4 are arranged in close communication through a first peristaltic pump 3-1 to realize sufficient mixing of the liquid in the reactor, the first aeration hollow fiber membrane assembly 4-1 is installed inside the MABR-PN / DN reactor 1-1, the first aeration hollow fiber membrane assembly 4-1 includes a gas inlet and a gas outlet, the gas inlet of the first aeration hollow fiber membrane assembly is arranged in close communication with the first lower gas inlet 9-1, and the gas outlet of the first aeration hollow fiber membrane assembly is arranged in close communication with the first upper gas outlet 9-2, the first aeration hollow fiber membrane assembly 4-1 in the MABR-PN / DN reactor 1-1 is filled with a first carrier 5-1 for fixing denitrifying bacteria, the first water inlet 2-1 can pass in the sewage to be treated, the sewage to be treated flows into the MABR-PN / DN reactor 1-1 from the first water inlet 2-1, and flows out of the reactor from the first water outlet 2-2;

[0040] The bottom of the MABR-PN / A reactor 1-2 is provided with a second lower gas inlet 9-3, and the top of the MABR-PN / A reactor 1-2 is provided with a second upper gas outlet 9-4; the upper part of the MABR-PN / A reactor is provided with a second water inlet 2-6 and a second upper internal reflux port 2-8, and the lower part of the MABR-PN / A reactor 1-2 is provided with a second lower internal reflux port 2-9, a second external reflux port 2-10 and a second water outlet 2-7; the second upper internal reflux port 2-8 and the second lower internal reflux port 2-9 are connected by a third peristaltic pump 3-3 to realize sufficient mixing of the liquid in the reactor; the second aeration hollow fiber membrane assembly 4-2 is installed in the hollow interior of the MABR-PN / A reactor 1-2, and the second aeration hollow fiber membrane assembly 4-2 includes a gas inlet and a gas outlet; the gas inlet of the second aeration hollow fiber membrane assembly is in close communication with the second lower gas inlet 9-3, and the gas outlet of the second aeration hollow fiber membrane assembly is in close communication with the second upper gas outlet 9-4; the second carrier 5-2 is filled on the second aeration hollow fiber membrane assembly 4-2 in the MABR-PN / A reactor 1-2 to fix anaerobic ammonia oxidation bacteria; and the second water outlet 2-7 is connected with a fifth peristaltic pump 3-5 to discharge the treated water from the reactor.

[0041] The first lower gas inlet 9-1 of the MABR-PN / DN reactor is further connected with a first aeration pump 8-1, a first gas flow meter 7-1 and a first pressure gauge 6-1; the first gas flow meter 7-1 is used to monitor the aeration amount, and the first pressure gauge 6-1 is used to monitor the aeration pressure to realize precise aeration and establish a short nitrification process.

[0042] The second lower gas inlet 9-3 of the MABR-PN / A reactor 1-2 is further connected with a second aeration pump 8-2, a second gas flow meter 7-2 and a second pressure gauge 6-2; the second gas flow meter 7-2 is used to monitor the aeration amount, and the second pressure gauge 6-2 is used to monitor the aeration pressure to realize precise aeration and establish a short nitrification process.

[0043] The first water outlet 2-2 of the MABR-PN / DN reactor 1-1 is connected with the second water inlet 2-6 of the MABR-PN / A reactor by a second peristaltic pump 3-2 and a first liquid flow meter 10-1, and the second external reflux port 2-5 of the MABR-PN / A reactor 1-2 is connected with the second external reflux port 2-10 by a fourth peristaltic pump 3-4 and a second liquid flow meter 10-2 to realize reflux liquid flow control.

[0044] After the wastewater to be treated enters the MABR-PN / DN reactor, the first aeration pump, the first peristaltic pump are started, the aeration amount is adjusted to establish the short-cut nitrification and denitrification process, the organic matter in the wastewater is reduced, and the proportion of ammonia nitrogen and nitrite is regulated, so that the COD in the reactor is reduced to below 70 mg / L, the mass ratio of ammonia nitrogen to nitrite is greater than 1:1.32, the second peristaltic pump is started, the effluent from the MABR-PN / DN reactor after treatment enters the MABR-PN / A reactor, the second aeration pump and the third peristaltic pump are started, the aeration amount is adjusted to establish the short-cut nitrification and anaerobic ammonia oxidation process, the advanced denitrification of the wastewater is realized, the fourth peristaltic pump is started, the water treated by the MABR-PN / A reactor is returned to the MABR-PN / DN reactor, the nitrate generated by the anaerobic ammonia oxidation reaction in the MABR-PN / A reactor is consumed by the denitrification reaction in the MABR-PN / DN reactor, and the fifth peristaltic pump is started to discharge the water treated by the MABR-PN / A reactor.

[0045] In the embodiment, the first aeration hollow fiber membrane assembly 4-1 and the second aeration hollow fiber membrane assembly 4-2 are both microporous hollow fiber aeration membranes or non-porous hollow fiber aeration membranes, the membrane aeration has the characteristics of high oxygen utilization rate and precise control of aeration amount, and can effectively realize short-cut nitrification control.

[0046] Preferably, the material of the microporous hollow fiber aeration membrane is PVDF or PTFE or PE, and the membrane pore size is 0.01-0.2 μm; the material of the non-porous hollow fiber aeration membrane is non-porous silicone rubber.

[0047] The application of the high-efficiency denitrification system of two-stage MABR as described above in the treatment of low carbon-nitrogen ratio wastewater containing ammonia nitrogen.

[0048] Embodiment 1

[0049] A high-efficiency denitrification system based on two-stage MABR, the related structural connection relationship is the same as above, specifically: the volume of the first-stage MABR-PN / DN reactor is 5 L, the first aeration hollow fiber membrane assembly is a microporous hollow fiber aeration membrane with a pore size of 0.2 μm and made of PVDF material, the assembly membrane area is 0.3 m 2 , the first carrier is polyurethane sponge filler, and the filling rate is 30%, the volume of the MABR-PN / A reactor is 5 L, the second aeration hollow fiber membrane assembly is a microporous hollow fiber aeration membrane with a pore size of 0.2 μm and made of PVDF material, the assembly membrane area is 0.3 m 2 , and the second carrier is polyurethane sponge filler with a filling rate of 30%.

[0050] Embodiment 2 High-efficiency denitrification method

[0051] The efficient denitrification method based on two-stage MABR, which uses the efficient denitrification reactor based on two-stage MABR described in Example 1, comprises the following steps:

[0052] 1) Start-up phase

[0053] The nitrifying sludge (MLSS 3500 mg / L) is inoculated in the first-stage MABR-PN / DN reactor, and NH4Cl is fed in, NH4 + The concentration of N is 100 mg / L, the pH is adjusted to 8.0 by NaHCO3, the aeration flow meter and the aeration pressure are adjusted, the dissolved oxygen is controlled to be 1.0 mg / L, the hydraulic retention time is controlled to be 18 h, after 20 days of operation, the mass ratio of nitrite nitrogen to total nitrate nitrogen in the effluent is higher than 90%, obvious biofilm is formed on the membrane surface, the sludge-water mixture is poured out, the denitrifying sludge (MLSS 3000 mg / L) is inoculated, and the polyurethane carrier is simultaneously added, the filling rate is 30%, the mixed solution of NH4Cl and glucose is fed in, NH4 + The concentration of N is 100 mg / L, the pH is adjusted to 8.0 by NaHCO3, the aeration flow meter and the aeration pressure are adjusted, the dissolved oxygen is controlled to be 1.0 mg / L, the hydraulic retention time is controlled to be 18 h, after 20 days of operation, the mass ratio of nitrite nitrogen to total nitrate nitrogen in the effluent is higher than 90%, obvious biofilm is formed on the membrane surface, the sludge-water mixture is poured out, the denitrifying sludge (MLSS 3000 mg / L) is inoculated, and the polyurethane carrier is simultaneously added, the filling rate is 30%, the mixed solution of NH4Cl and glucose is fed in, NH4

[0054] The nitrifying sludge (MLSS 3500 mg / L) is inoculated in the second-stage MABR-PN / A reactor, and NH4Cl is fed in, NH4 + The concentration of N is 100 mg / L, the pH is adjusted to 8.0 by NaHCO3, the aeration flow meter and the aeration pressure are adjusted, the dissolved oxygen is controlled to be 1.0 mg / L, the hydraulic retention time is controlled to be 18 h, after 20 days of operation, the mass ratio of nitrite nitrogen to total nitrate nitrogen in the effluent is higher than 90%, obvious biofilm is formed on the membrane surface, the sludge-water mixture is poured out, the denitrifying sludge (MLSS 3000 mg / L) is inoculated, and the polyurethane carrier is simultaneously added, the filling rate is 30%, the mixed solution of NH4Cl and glucose is fed in, NH4 + The concentration of N is 100 mg / L, the pH is adjusted to 8.0 by NaHCO3, the aeration flow meter and the aeration pressure are adjusted, the dissolved oxygen is controlled to be 1.0 mg / L, the hydraulic retention time is controlled to be 18 h, after 20 days of operation, the mass ratio of nitrite nitrogen to total nitrate nitrogen in the effluent is higher than 90%, obvious biofilm is formed on the membrane surface, the sludge-water mixture is poured out, the denitrifying sludge (MLSS 3000 mg / L) is inoculated, and the polyurethane carrier is simultaneously added, the filling rate is 30%, the mixed solution of NH4Cl and glucose is fed in, NH4

[0055] 2) Operation phase

[0056] The first-stage MABR-PN / DN reactor: the influent is simulated high-ammonia-nitrogen wastewater prepared by mixing NH4Cl and glucose, NH4 +- N concentration of 100 mg / L, COD concentration of 150 mg / L, pH adjusted to 8 with NaHCO3, dissolved oxygen controlled to 0.5 mg / L by adjusting aeration flow rate and aeration pressure, hydraulic retention time of 8 h, and temperature of 25℃.

[0057] Second-stage MABR-PN / A reactor: influent was the effluent of the first-stage MABR-PN / DN reactor, and the dissolved oxygen was 0.2 mg / L. The hydraulic retention time was 8 h, the temperature was 32℃, and the reflux ratio was 50%.

[0058] The water quality parameters during stable operation are shown in Table 1. After the first-stage MABR-PN / DN treatment, the COD decreased from 150 mg / L in the influent to 60-65 mg / L, so the inhibition of organic matter on the anaerobic ammonium oxidation reaction in the second-stage MABR-PN / A was greatly reduced, and the total nitrogen removal rate of the system was higher than 92%.

[0059] Table 1, water quality of effluent of each stage of the two-stage MABR in Example 2

[0060]

[0061] Comparative Example 1

[0062] The first-stage MABR-PN / DN reactor used in Example 2 was used to treat the ammonia-nitrogen-containing wastewater, but was not used in combination with the second-stage MABR-PN / A reactor. The remaining steps were the same as in Example 2.

[0063] The simulated high-ammonia-nitrogen wastewater was prepared by mixing NH4Cl and glucose, and the concentration of NH4 + - N concentration of 100 mg / L, COD concentration of 150 mg / L, pH adjusted to 8 with NaHCO3, dissolved oxygen controlled to 0.5 mg / L by adjusting aeration flow rate and aeration pressure, hydraulic retention time of 8 h, and temperature of 25℃.

[0064] The water quality parameters during stable operation are shown in Table 2. Due to the low carbon-nitrogen ratio (1.5:1) in the influent, there was a problem of insufficient carbon source for denitrification in the MABR-PN / DN reactor, resulting in a total nitrogen removal rate of only about 50%.

[0065] Table 2, water quality of influent and effluent in Comparative Example 1

[0066]

[0067] Comparative Example 2

[0068] The second-stage MABR-PN / A reactor used in Example 2 was used to treat the wastewater, but was not used in combination with the first-stage MABR-PN / DN reactor. The remaining steps were the same as in Example 2.

[0069] The simulated high-ammonia-nitrogen wastewater was prepared by mixing NH4Cl and glucose, NH4 + The concentration of -N was 100 mg / L, the concentration of COD was 150 mg / L, the pH was adjusted to 8 by NaHCO3, the dissolved oxygen was controlled to be 0.1 mg / L by aeration flow and aeration pressure, the hydraulic retention time was 16 h, and the temperature was 32 DEG C.

[0070] The water quality parameters in the stable operation are shown in Table 3. Due to the inhibition of COD on the anaerobic ammonia oxidation process in the MABR-PN / A reactor, the total nitrogen removal rate of the system is less than 20%.

[0071] Meanwhile, by comparing Example 2, Comparative Example 1 and Comparative Example 2, it can be seen that the first-stage MABR reactor, i.e., the MABR-PN / DN reactor, and the second-stage MABR reactor, i.e., the MABR-PN / A reactor, have a synergistic effect, which can synergistically improve the denitrification effect of the prepared high-efficiency denitrification system on ammonia-nitrogen-containing wastewater.

[0072] Table 3 Water quality of influent and effluent in Comparative Example 2

[0073]

[0074] Comparative Example 3

[0075] A two-stage MABR-PN / A process was constructed by using the same second-stage MABR-PN / A reactor as that in Example 2 to treat ammonia-nitrogen-containing wastewater.

[0076] The simulated high-ammonia-nitrogen wastewater was prepared by mixing NH4Cl and glucose, NH4 + The concentration of -N was 100 mg / L, the concentration of COD was 150 mg / L, the pH was adjusted to 8 by NaHCO3, the dissolved oxygen was controlled to be 0.1 mg / L by aeration flow and aeration pressure, the hydraulic retention time was 16 h, and the temperature was 32 DEG C.

[0077] The water quality parameters in the stable operation are shown in Table 4. In the two-stage MABR-PN / A, the first-stage anaerobic ammonia oxidation is significantly inhibited by COD, and the total nitrogen removal rate is only 10%; the COD concentration in the second stage is slightly lower than that in the first stage, and the inhibition of anaerobic ammonia oxidation is also reduced. However, the two-stage MABR-PN / A system is still greatly affected by COD, and the total nitrogen removal rate is less than 50%, which is lower than that of the MABR-PN / DN and MABR-PN / A series systems.

[0078] Table 4 Water quality of effluent in each stage in Comparative Example 3

[0079]

[0080] Meanwhile, it can be seen from the comparison between Comparative Example 2, Comparative Example 1 and Comparative Example 2-3 that the first-stage MABR reactor, i.e., the MABR-PN / DN reactor, and the second-stage MABR reactor, i.e., the MABR-PN / A reactor, have a synergistic effect, and can synergistically improve the denitrification effect of the prepared high-efficiency denitrification system on ammonia-nitrogen-containing wastewater.

[0081] Therefore, the high-efficiency denitrification reactor and method based on two-stage MABR have the characteristics of high denitrification rate, reduced aeration energy consumption and less carbon source requirement, and are suitable for high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater treatment.

[0082] The system of the present application utilizes the series connection design of the MABR-PN / DN and the MABR-PN / A, reduces the adverse effect of organic matter in wastewater on the treatment of high-concentration ammonia-nitrogen wastewater by anaerobic ammonia oxidation, and realizes denitrification by returning the nitrate nitrogen produced by the MABR-PN / A to the first-stage MABR-PN / DN, breaks through the denitrification limitation of a single reactor and a single denitrification path, and the total nitrogen removal rate of the system is higher than 90%.

[0083] Although the embodiments of the present application are disclosed for the purpose of illustration, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present application and the appended claims, and therefore, the scope of the present application is not limited to the disclosed content.

Claims

1. A highly efficient nitrogen removal method utilizing a two-stage MABR-based high-efficiency nitrogen removal system, characterized in that: Includes the following steps: 1) Start-up phase The MABR-PN / DN reactor (1-1) does not have a first carrier. The first-stage MABR reactor, i.e., the MABR-PN / DN reactor (1-1), is inoculated with nitrifying sludge. The sludge concentration (MLSS) is 3000-5000 mg / L. NH4Cl is introduced to make the solution NH4+. + The nitrite concentration was 100 mg / L. The pH was adjusted to 7.5-8.0 with NaHCO3, and the dissolved oxygen was controlled at 1.0-1.2 mg / L. The hydraulic retention time was controlled by adjusting the influent flow rate, and the dissolved oxygen in the reactor was controlled by adjusting the aeration pressure. The reactor was operated until the nitrite accumulation rate in the effluent exceeded 90%, and a significant biofilm formed on the membrane surface. The sludge-water mixture was then poured out, and denitrifying sludge was inoculated with a sludge concentration (MLSS) of 3000-5000 mg / L. Simultaneously, the first carrier (5-1) of the MABR-PN / DN reactor (1-1) was added, with a filling rate of 15-45%. NH4Cl and glucose were introduced to increase the NH4 content in the solution. + Start-up is considered successful when the nitrogen concentration is 100 mg / L, the COD is 200 mg / L, the pH is adjusted to 7.5-8.0 with NaHCO3, the dissolved oxygen is controlled at 0.3-0.5 mg / L, and the total nitrogen removal rate is >50%. No second carrier is used in the MABR-PN / A reactor (1-2). The second-stage MABR reactor, i.e., the MABR-PN / A reactor (1-2), is inoculated with nitrifying sludge at a MLSS concentration of 3000-5000 mg / L. NH4Cl is introduced to make the solution NH4+. + The nitrogen (N) concentration was 100 mg / L. The pH was adjusted to 7.5–8.0 with NaHCO3, and the dissolved oxygen was controlled at 1.0–1.2 mg / L. The hydraulic retention time was controlled by adjusting the influent flow rate, and the dissolved oxygen in the reactor was controlled by adjusting the aeration pressure. The reactor was operated until the nitrite accumulation rate in the effluent exceeded 90%, and a significant biofilm formed on the membrane surface. The mud-water mixture was then poured out, and anaerobic ammonia-oxidizing bacteria with a VSS of 4000–5000 mg / L were inoculated. Simultaneously, the second carrier (5-2) of the MABR-PN / A reactor was added, with a filling rate of 15–45%. NH4Cl was introduced to increase the NH4+ concentration in the solution. + Start-up was completed when the TN removal rate was >80% for 10 consecutive days, with a TN concentration of 100 mg / L, dissolved oxygen <0.2 mg / L, temperature 30-35℃. 2) Operational Phase The first-stage MABR reactor, namely the MABR-PN / DN reactor (1-1), controls the dissolved oxygen at 0.3~0.5 mg / L, the hydraulic retention time at 5~10 h, and the temperature at 15~35℃. The second-stage MABR reactor, namely the MABR-PN / A reactor (1-2), controls dissolved oxygen <0.2mg / L, with the same hydraulic retention time as the first-stage MABR reactor, and a temperature of 30-35℃. Every 5-15 days, a trace amount of hydroxylamine with a final concentration of 0.5 mg / L is added to promote the activity of anaerobic ammonia oxidizing bacteria. Connect the first-stage MABR reactor and the second-stage MABR reactor, and adjust the reflux ratio to 50~150%; The high-efficiency denitrification system based on a two-stage MABR includes a first-stage MABR reactor, namely the MABR-PN / DN reactor (1-1), a second-stage MABR reactor, namely the MABR-PN / A reactor (1-2), a first peristaltic pump (3-1), a second peristaltic pump (3-2), a third peristaltic pump (3-3), a fourth peristaltic pump (3-4), a fifth peristaltic pump (3-5), a first aeration hollow fiber membrane module (4-1), a second aeration hollow fiber membrane module (4-2), a first carrier (5-1), a second carrier (5-2), a first aeration pump (8-1), a second aeration pump (8-2), a first gas flow meter (7-1), a second gas flow meter (7-2), a first pressure gauge (6-1), a second pressure gauge (6-2), a first liquid flow meter (10-1), and a second liquid flow meter (10-2). Both the MABR-PN / DN reactor (1-1) and the MABR-PN / A reactor (1-2) are arranged vertically. The material in the MABR-PN / DN reactor (1-1) flows into the MABR-PN / A reactor (1-2) through the second peristaltic pump (3-2) and the first liquid flow meter (10-1). The material in the MABR-PN / A reactor (1-2) flows back into the MABR-PN / DN reactor (1-1) through the fourth peristaltic pump (3-4) and the second liquid flow meter (10-2), forming a loop. The material in the MABR-PN / DN reactor (1-1) flows back into the MABR-PN / DN reactor (1-1) through the first peristaltic pump (3-1). The material in the MABR-PN / A reactor (1-2) flows back into the MABR-PN / A reactor (1-2) through the third peristaltic pump (3-3). The product material in the BR-PN / A reactor (1-2) is discharged through the fifth peristaltic pump (3-5). The first aeration hollow fiber membrane module (4-1) and the first carrier (5-1) are used to filter the material in the MABR-PN / DN reactor (1-1). The second aeration hollow fiber membrane module (4-2) and the second carrier (5-2) are used to filter the material in the MABR-PN / A reactor (1-2). The first aeration pump (8-1), the first gas flow meter (7-1), and the first pressure gauge (6-1) are used to detect the parameters of the MABR-PN / DN reactor (1-1). The second aeration pump (8-2), the second gas flow meter (7-2), and the second pressure gauge (6-2) are used to detect the parameters of the MABR-PN / A reactor (1-2).

2. The efficient denitrification method according to claim 1, characterized in that: The MABR-PN / DN reactor (1-1) is a hollow, sealed structure. A first lower air inlet (9-1) is tightly connected to the bottom of the MABR-PN / DN reactor (1-1), and a first upper air outlet (9-2) is tightly connected to the top of the MABR-PN / DN reactor (1-1). Gas can enter the first aeration hollow fiber membrane module (4-1) inside the MABR-PN / DN reactor (1-1) through the first lower air inlet (9-1) and exit the MABR-PN / DN reactor (1-1) through the first upper air outlet (9-2). A first water inlet (2-1), a first upper internal reflux inlet (2-3), and a first external reflux inlet (2-5) are connected to the upper part of the MABR-PN / DN reactor (1-1). A first lower internal reflux inlet (2-4) and a first water outlet (2-2) are connected to the lower part of the MABR-PN / DN reactor (1-1). The return port (2-3) and the first lower internal return port (2-4) are connected through the first peristaltic pump (3-1). The first aeration hollow fiber membrane module (4-1) is installed inside the MABR-PN / DN reactor (1-1). The first aeration hollow fiber membrane module (4-1) includes an air inlet and an air outlet. The air inlet of the first aeration hollow fiber membrane module is tightly connected to the first lower air inlet (9-1). The air outlet of the first aeration hollow fiber membrane module is tightly connected to the first upper air outlet (9-2). The first carrier (5-1) inside the MABR-PN / DN reactor (1-1) is filled with a first carrier (5-1) for fixing denitrifying bacteria. The first inlet can be used to introduce wastewater to be treated. The wastewater to be treated flows into the MABR-PN / DN reactor (1-1) from the first inlet and flows out of the MABR-PN / DN reactor (1-1) from the first outlet (2-2). The MABR-PN / A reactor (1-2) has a second lower air inlet (9-3) at its bottom and a second upper air outlet (9-4) at its top. The upper part of the MABR-PN / A reactor (1-2) has a second water inlet (2-6) and a second upper internal reflux inlet (2-8). The lower part of the MABR-PN / A reactor (1-2) has a second lower internal reflux inlet (2-9), a second external reflux inlet (2-10), and a second water outlet (2-7). The second upper internal reflux inlet (2-8) and the second lower internal reflux inlet (2-9) are connected via a third peristaltic pump (3-3). The second aeration hollow fiber membrane module (4- 2) Installed inside the hollow interior of the MABR-PN / A reactor (1-2), the second aeration hollow fiber membrane module (4-2) includes an air inlet and an air outlet. The air inlet of the second aeration hollow fiber membrane module (4-2) is tightly connected to the second lower air inlet (9-3), and the air outlet of the second aeration hollow fiber membrane module (4-2) is tightly connected to the second upper air outlet (9-4). The second carrier (5-2) inside the MABR-PN / A reactor (1-2) is filled with a second carrier (5-2) for fixing anaerobic ammonia oxidizing bacteria. The second water outlet (2-7) is connected to the fifth peristaltic pump (3-5) to discharge the treated water from the reactor. The first lower air inlet (9-1) of the MABR-PN / DN reactor (1-1) is also connected to the first aeration pump (8-1), the first gas flow meter (7-1), and the first pressure gauge (6-1). The first gas flow meter (7-1) is used to monitor the air flow rate, and the first pressure gauge (6-1) is used to monitor the aeration pressure. The second lower air inlet (9-3) under the MABR-PN / A reactor (1-2) is also connected to the second aeration pump (8-2), the second gas flow meter (7-2), and the second pressure gauge (6-2). The second gas flow meter (7-2) is used to monitor the air flow rate, and the second pressure gauge (6-2) is used to monitor the aeration pressure. The first outlet (2-2) of the MABR-PN / DN reactor (1-1) and the second inlet (2-6) of the MABR-PN / A reactor are tightly connected through a second peristaltic pump (3-2) and a first liquid flow meter (10-1). The second external return port (2-10) of the MABR-PN / A reactor (1-2) and the first external return port (2-5) are tightly connected through a fourth peristaltic pump (3-4) and a second liquid flow meter (10-2) to achieve control of the return liquid flow rate.

3. The efficient denitrification method according to claim 1, characterized in that: The first aeration hollow fiber membrane module (4-1) and the second aeration hollow fiber membrane module (4-2) are both microporous hollow fiber aeration membranes or non-porous hollow fiber aeration membranes.

4. The efficient denitrification method according to claim 3, characterized in that: The microporous hollow fiber aeration membrane is made of PVDF, PTFE, or PE, with a pore size of 0.01~0.2μm; the non-porous hollow fiber aeration membrane is made of non-porous silicone rubber.

5. The efficient denitrification method according to claim 1, characterized in that: Both the first carrier (5-1) and the second carrier (5-2) are sponge packing, combined packing, or elastic packing.

6. The efficient denitrification method according to claim 1, characterized in that: In step 2), the mass ratio of ammonia nitrogen to nitrite nitrogen in the effluent of the first-stage MABR reactor is greater than 1:1.

32.

7. The application of the efficient denitrification method as described in any one of claims 1 to 6 in the treatment of ammonia nitrogen-containing wastewater with a low carbon-to-nitrogen ratio.

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