Method for realizing rapid nitrous accumulation through short-cut nitrification and endogenous short-cut denitrification coupled flora

Abstract

The invention relates to a method for realizing rapid nitrous accumulation through short-cut nitrification and endogenous short-cut denitrification coupled flora, and belongs to the technical field of nitrogen-containing sewage treatment in environmental protection. According to the method disclosed by the invention, short-cut nitrification and endogenous short-cut denitrification coupling is realized, rapid nitrous accumulation can be realized, an organic carbon source does not need to be consumed, and the consumption of substances and energy is reduced. Meanwhile, the method provided by the invention not only can be used for treating the wastewater containing ammonia nitrogen, but also can be used for treating the wastewater containing nitrate nitrogen, solves the problem that nitrate nitrogen is generated due to partial whole-process nitrification in short-cut nitrification, and can ensure high-efficiency and long-term stable accumulation of nitrous; and a quick starting method is provided for a sewage plant adopting a short-cut denitrification related process.

Description

Technical Field

[0001] The invention relates to a method for realizing rapid accumulation of nitrous acid by coupling bacterial communities with short-range nitrification and endogenous short-range denitrification, belonging to the technical field of nitrogen-containing sewage treatment in environmental protection. Background Art

[0002] The treatment of nitrogen-containing wastewater is one of the important tasks in the field of environmental pollution control. Sewage plants generally use the traditional nitrification-denitrification process for denitrification. This process is easy to control and has excellent denitrification effect; however, this process consumes a lot of oxygen in the nitrification process and requires a large amount of organic carbon source in the denitrification stage, resulting in huge energy and material consumption and increased denitrification costs. Moreover, with the rapid development of society and economy, more and more low-carbon source wastewater is produced. The lack of carbon source not only limits the denitrification efficiency, but also increases the cost of sewage treatment. The nitrification-denitrification process has become increasingly unsuitable for current sewage treatment requirements. In recent years, short-term denitrification processes have been widely studied and developed, including short-term nitrification-denitrification processes, anaerobic ammonia oxidation processes, etc., which can be used to treat low-carbon source wastewater. Short-term denitrification processes all rely on the provision of nitrous substrates, and most nitrogen-containing wastewaters only contain nitrate nitrogen. Therefore, it is necessary to combine processes that can provide nitrous to achieve short-term denitrification. Therefore, achieving rapid and stable nitrous accumulation is the key to achieving short-term denitrification.

[0003] A Chinese invention patent with a publication date of May 28, 2024 and publication number CN118084188A discloses a method for accelerating the start-up of short-term nitrification by sludge pretreatment. Specifically, the inoculated sludge is first placed in a low ammonia nitrogen (0-10 mg / L) and low dissolved oxygen (0-4 mg / L) environment for 1-20 days, and then domestic sewage (whose ammonia nitrogen concentration is 50±2 mg / L) is passed into the pretreated sludge to achieve a nitrite accumulation rate of more than 90% in a short period of time.

[0004] A Chinese invention patent with a publication date of November 25, 2022 and publication number CN115385443A discloses a method and device for rapid startup and stable operation of short-range nitrification of low-temperature, low-ammonia nitrogen wastewater. It specifically discloses that at 4 to 34°C, activated sludge containing heterotrophic nitrifying bacteria and functional bacteria is inoculated into the reactor, and by optimizing the operation strategy and utilizing the interspecies competition mechanism of microorganisms, the activity of nitrite oxidizing bacteria can be rapidly inhibited and a large number of functional bacteria can be enriched.

[0005] A Chinese invention patent with a publication date of November 22, 2022 and publication number CN115367869A discloses a method for the stable accumulation of nitrite nitrogen in short-term denitrification based on mixed nutrition. It specifically discloses that according to the amount of electrons gained or lost in denitrification, part of the organic matter is replaced by sulfide and ferrous ions, and the full-process denitrifying bacteria in the reactor are gradually screened and washed out of the reactor, so that the nitrous oxide in the reactor is not further reduced to nitrogen gas, thereby achieving stable nitrous oxide accumulation.

[0006] A Chinese invention patent with a publication date of February 8, 2022 and publication number CN114014439A discloses a real-time control method for rapid startup and stable operation of short-range denitrification. It specifically discloses the use of nitrate nitrogen sensors and COD sensors to real-time detect the nitrate nitrogen and COD concentrations in the inlet and outlet water, and the use of a PLC program to accurately control the COD dosage, thereby achieving rapid startup and stable operation of short-range denitrification.

[0007] However, the existing technology mainly focuses on a single process of short-range nitrification or short-range denitrification, which is only suitable for treating wastewater containing ammonia nitrogen or nitric nitrogen, and cannot treat wastewater containing both ammonia nitrogen and nitric nitrogen. Summary of the invention

[0008] The purpose of the present invention is to provide a method for realizing rapid accumulation of nitrous oxide by coupling bacterial flora with short-range nitrification and endogenous short-range denitrification, and to provide a method capable of treating wastewater containing both ammonia nitrogen and nitrate nitrogen, thereby realizing rapid accumulation of nitrous oxide.

[0009] In order to achieve the above-mentioned purpose, the technical scheme of the method for realizing rapid accumulation of nitrous oxide by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora in the present invention is:

[0010] A method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with a bacterial community comprises the following steps:

[0011] (1) Starve the return sludge or excess sludge under anoxic conditions to make the relative abundance of ammonia oxidizing bacteria and nitrite oxidizing bacteria ≤ 1% and the relative abundance of filamentous bacteria > 40%;

[0012] (2) aerating the sludge obtained through starvation culture in step (1) in wastewater in an intermittent operation manner, so that the relative abundance of ammonia oxidizing bacteria is greater than 4%, the relative abundance of nitrite oxidizing bacteria is less than 1%, and the relative abundance of filamentous bacteria is less than 30%; the ammonia nitrogen concentration in the wastewater is 50-400 mg / L, the nitrous acid concentration is 0-5 mg / L, the nitrate nitrogen concentration is 5-50 mg / L, the COD is less than 10 mg / L, and the ammonia nitrogen / nitrate nitrogen ratio is ≥10;

[0013] (3) the sludge aerated in step (2) is further aerated in the wastewater for 28-40 days, followed by anoxic starvation culture, and then further aerated in the wastewater to achieve a relative abundance of ammonia oxidizing bacteria greater than 20%, a relative abundance of nitrite oxidizing bacteria less than 1%, and an endogenous short-range denitrifying bacteria greater than 10%;

[0014] (4) The sludge from step (3) is converted to continuous flow MBR operation, so that the relative abundance of ammonia oxidizing bacteria is greater than 15%, the relative abundance of endogenous short-range denitrifying bacteria is ≥ 15%, the relative abundance of nitrite oxidizing bacteria is less than 1%, and the relative abundance of filamentous bacteria is less than 1%.

[0015] The beneficial effect of the above technical scheme is that: the method of the present invention for realizing rapid accumulation of nitrous acid by coupling bacterial communities with short-term nitrification and endogenous short-term denitrification is a pioneering invention. The present invention utilizes the different characteristics of short-term nitrifying bacteria and nitrifying bacteria in terms of starvation tolerance and oxygen demand, as well as the different carbon source utilization capabilities and demand of denitrifying bacteria and endogenous short-term denitrifying bacteria, and screens the bacterial community through the first starvation culture, eliminates most of the nitrifying bacteria, and retains the short-term nitrifying bacteria; after aeration operation, starvation culture is performed again to strengthen the bacterial community composition, weaken the abundance of nitrifying bacteria again, and ensure the absolute dominance of nitrite bacteria. At the same time, the bacterial community eliminated during the starvation period and the substances such as EPS and SMP secreted by them are used as endogenous carbon sources for short-term denitrification, ensuring the dominant position of endogenous short-term denitrifying bacteria, thereby realizing the co-growth of short-term nitrifying bacteria and short-term denitrifying bacteria in the same treatment system, and the two bacterial communities are coupled to realize the rapid accumulation of nitrous acid in the sewage denitrification treatment process. Short-range nitrifying bacteria can convert ammonia nitrogen into nitrous oxide, and short-range denitrifying bacteria can use the endogenous carbon source released under long sludge age conditions to reduce nitrate nitrogen to nitrous oxide, which not only helps the stable accumulation of nitrous oxide, but also avoids the excessive generation of nitrate nitrogen in short-range nitrification, thereby achieving stable and efficient nitrous oxide accumulation. In addition, the intermittent flow operation mode is more suitable for bacterial cultivation, while the continuous flow MBR operation mode is more suitable for actual sewage treatment. The several stages of the method of the present invention combine the intermittent flow operation mode and the continuous flow MBR operation mode, and simultaneously achieve the efficient growth of beneficial bacteria and the stable and efficient nitrous oxide accumulation.

[0016] Furthermore, the method for realizing rapid accumulation of nitrous oxide based on two bacterial communities of the present invention has the advantages of simple operation, low operating cost, small footprint, short startup cycle, wide application range and stable operation. After 17 days of using the method, stable nitrous oxide accumulation occurs. At the same time, the method of the present invention can not only treat wastewater containing ammonia nitrogen, but also treat wastewater containing nitric nitrogen, and solves the problem that partial full-process nitrification and subsequent generation of nitric nitrogen exist in short-term nitrification, and can ensure efficient and long-term stable accumulation of nitrous oxide, and provide a method for rapid startup for sewage treatment plants using short-term denitrification-related processes.

[0017] Specifically, the abundance of filamentous bacteria represents the state of anoxic and hungry sludge. The massive growth of filamentous bacteria indicates that there is a lack of substrate in the sludge. Some microorganisms die due to starvation, and filamentous bacteria can use these residues to grow. After aeration culture, due to the presence of oxygen and substrate, normal microorganisms begin to grow and the abundance of filamentous bacteria begins to decrease.

[0018] As a further improvement, the conditions of aeration culture in step (2) are as follows: aeration volume of 0.005-0.02 L / h / kg ammonia nitrogen, dissolved oxygen of 0.2-1.0 mg / L, free ammonia>10 mg / L, water exchange ratio>60%.

[0019] As a further improvement, the endogenous short-range denitrifying bacteria in step (3) include Arenimonas, OLB8, and Truepera.

[0020] As a further improvement, the continuous flow MBR operation conditions are as follows: aeration volume is 0.005-0.01 L / h / kg ammonia nitrogen, hydraulic retention time is 8-24 h, sludge age is 50-100 days, and sludge age / hydraulic retention time>100.

[0021] As a further improvement, in step (4), the sludge concentration is >8000 mg / L, the soluble microbial products are >100 mg / L, and the extracellular polymers are >20 mg / g SS.

[0022] As a further improvement, the starvation culture time in step (1) is 7-10 days.

[0023] As a further improvement, the aeration culture time in step (2) is 10-20 days.

[0024] As a further improvement, the duration of the anoxic starvation culture in step (3) is 7-15 days, and then the duration of the aerated culture in the wastewater is continued for 10-40 days.

[0025] As a further improvement, after the starvation culture and aeration culture in step (3), when the relative abundance of the ammonia oxidizing bacteria is less than 20%, the starvation culture and aeration culture are repeated. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the operation mechanism of the reactor at different stages of the present invention;

[0027] Figure 2 The composition of the functional microorganisms in Example 1 of the present invention is changed;

[0028] Figure 3 is a graph showing changes in nitrogen concentration and nitrous acid accumulation rate in Example 1 of the present invention;

[0029] Figure 4 is the change of EPS and SMP in Example 1 of the present invention;

[0030] Figure 5 This is a graph showing changes in key enzyme activity in Example 1 of the present invention;

[0031] Figure 6 Graph showing changes in nitrogen concentration and nitrous acid accumulation rate in Example 2 of the present invention. DETAILED DESCRIPTION

[0032] In the treatment of sewage denitrification, the nitrification-denitrification process is a sewage microbial denitrification treatment method using nitrifying bacteria and denitrifying bacteria, which is divided into two stages: nitrification and denitrification. Nitrogen-containing substances are converted into nitrates by nitrifying bacteria in sewage under aerobic conditions, and then nitrates are reduced to gaseous nitrogen by denitrifying bacteria in sewage under anoxic conditions. Two-stage biological denitrification is an effective method for sewage microbial denitrification, and has been widely used as a standard biological denitrification method. However, with the restriction of nitrogen emissions and the increasing demand for carbon emission reduction, traditional nitrification and denitrification processes are facing bottleneck problems. Short-range nitrification-denitrification processes have been widely studied and developed.

[0033] Short-range nitrification is the process of converting ammonia nitrogen into nitrous oxide under the action of ammonia oxidizing bacteria, limiting the nitrification reaction to the nitrous oxide stage, thereby achieving stable accumulation of nitrous oxide. Short-range denitrification refers to the process of converting the four stages (NO3 - —NO2 - —NO—N2O—N2) the whole denitrification process ends in the first stage (NO3 - —NO2 - ) to achieve the accumulation of nitrite. At present, the existing technology mainly focuses on a single process of short-range nitrification or short-range denitrification, which is only suitable for treating wastewater containing ammonia nitrogen or nitric nitrogen, and cannot treat wastewater containing both ammonia nitrogen and nitric nitrogen. Based on this, the present invention provides a method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora.

[0034] The present invention is used to achieve rapid accumulation of nitrous oxide in the sewage denitrification process by dividing the return sludge of the secondary sedimentation tank of the sewage treatment plant into different stages for cultivation and operation and controlling the cultivation conditions, coupling the short-range nitrifying bacteria group with the short-range denitrifying bacteria group. Short-range nitrifying bacteria can convert ammonia nitrogen into nitrous oxide, and short-range denitrifying bacteria can reduce nitrate nitrogen to nitrous oxide by using the endogenous carbon source released under the condition of long sludge age, which not only contributes to the stable accumulation of nitrous oxide, but also avoids the excessive generation of nitrate nitrogen in short-range nitrification, thereby achieving stable and efficient nitrous oxide accumulation.

[0035] The present invention is further described below in conjunction with specific implementation methods, but the protection scope of the present invention is not limited thereto; unless otherwise specified, various reagents, instruments, etc. used in the examples are commercially available products.

[0036] The intermittent operation cycle in the following embodiment of the present invention consists of four stages: water inlet, aeration culture, sedimentation, and water outlet. The water inlet and water outlet stages are instantaneous, generally lasting 1 to 5 minutes, and the sedimentation stage lasts about 30 minutes. After the water outlet stage is completed, the reactor is idle and runs two cycles in an intermittent operation mode every day.

[0037] A specific embodiment of the method for realizing rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial communities of the present invention:

[0038] The method of the present invention for achieving rapid accumulation of nitrous oxide by coupling short-range nitrification and endogenous short-range denitrification with bacterial communities consists of four stages. First, the return sludge or residual sludge from the secondary sedimentation tank of the sewage treatment plant is starved and cultured under anoxic conditions for 7-10 days; then the sludge that has completed the starvation culture is aerated and cultured in wastewater in an intermittent operation mode for 10-20 days; secondly, the operating conditions are maintained unchanged and aerated culture is continued for 30-40 days, and after starvation culture under anoxic conditions for 7-15 days, the previous operating conditions are maintained unchanged and aerated culture is continued for 10-40 days; finally, the sludge is switched to MBR continuous flow operation mode to achieve stable and efficient accumulation of nitrous oxide. The schematic diagram of the reactor operation mechanism of the present invention at different reaction stages is shown in the figure. Figure 1 shown.

[0039] Example 1

[0040] The method of this embodiment for achieving rapid accumulation of nitrous oxide by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora includes four stages, which are respectively recorded as P0 stage, P1 stage, P2 stage and P3 stage. The specific operation steps are as follows:

[0041] P0 stage: The return sludge from the secondary sedimentation tank of the municipal sewage treatment plant was taken and starved for 7 days under anoxic conditions. No substrate was provided during the culture period, and no reaction conditions were controlled. It was only left to stand in the laboratory reactor. Through starvation culture, on the one hand, the substrate remaining in the sludge was degraded, and on the other hand, heterotrophic microorganisms were eliminated. At the same time, AOB (Ammonia oxidizing bacteria) and NOB (Nitrite oxidizing bacteria) were inhibited to varying degrees by their different tolerance to starvation. After anoxic starvation culture, the relative abundance of AOB was 0.099%, the relative abundance of NOB was 0.04%, and the abundance of filamentous bacteria Candidatus_Microthrix was 44.3%, as shown in Table 1 and Figure 2 ( Figure 2 The data in the figure are rounded off during the mapping process).

[0042] Table 1 Changes in microbial abundance at each stage

[0043] P0 stage (%) P1 stage (%) P2 stage (%) P3 stage (%) Nitrosomonas 0.099 4.73 25.9 18.7 Candidatus_Microthrix 44.3 26.3 14.4 0.57 OLB8 0.014 0.62 6 12.1 OLB13 0.08 0.29 0.42 3.92 Arenimonas 0.02 0.11 1.1 9 Truepera 0 0 0.64 1.93 Nitrospira 0.04 0 0 0 Others 55.447 67.95 51.54 53.78

[0044] After the anoxic starvation culture stage, the P1 stage is entered. In this stage, artificially prepared wastewater is added to the reactor. The ammonia nitrogen concentration in the wastewater is 400 mg / L, the nitrous acid concentration is 0 mg / L, the nitrate nitrogen concentration is 5 mg / L, the COD is 0 mg / L, and the ammonia nitrogen / nitrate nitrogen ratio in the influent is 80. Aeration culture is carried out in an intermittent operation (SBR) mode, and the aeration volume is controlled to be 0.005 L / h / kg ammonia nitrogen, and gradually increased at a growth rate of 0.005, so that DO (dissolved oxygen) is about 0.65 mg / L; the alkalinity is 1600 mg / L, and FA (free ammonia) is 17.5 mg / L; during the intermittent operation reaction process, the ammonia nitrogen concentration is continuously monitored every hour. In the fourth hour of the reaction, the ammonia nitrogen concentration drops below 200 mg / L, so the aeration time is set to 8 hours and the water exchange ratio is 62.5%. After 17 days of operation, the relative abundance of AOB increased to 4.7%, the relative abundance of NOB was <1%, and the relative abundance of filamentous fungi Candidatus_Microthrix decreased to 26.3%, as shown in Tables 1 and Figure 2 shown.

[0045] In the P2 phase, the aeration volume and other conditions were kept constant and the system was operated for 32 consecutive days. The nitrous oxide accumulated steadily and the nitrous oxide accumulation rate was >90%. Figure 2 Then, the culture was starved for 11 days to increase the secretion of extracellular polymers and soluble microbial products, thereby inducing short-range denitrifiers. After that, the relative abundance of AOB increased to 25.9%, the relative abundance of NOB was <1%, and the endogenous short-range denitrifiers included Arenimonas, OLB8 and Truepera, and the sum of their relative abundances was 11%, as shown in Table 1 and Figure 2 After the anoxic starvation, the system switched to aerobic operation (the aeration volume and operating conditions were the same as those in the P1 stage) and continued to operate for 10 days. The NAR (nitrite accumulation rate, i.e. the above-mentioned nitrous acid accumulation rate) was > 95%. Figure 3 shown.

[0046] In the P3 stage, the aeration rate was maintained at 0.01 L / h / kg ammonia nitrogen, and a membrane module was added to the reactor. The membrane module was a hollow fiber membrane, and it was switched to continuous flow MBR operation. The hydraulic retention time HRT was controlled to 8 h, and the sludge age SRT was controlled to 100 days. With SRT / HRT>100, the sludge concentration was 9000 mg / L, the soluble microbial products were 125.7 mg / L, and the extracellular polymers were 23.4 mg / g SS, providing an endogenous carbon source for short-range denitrification, such as Figure 4 The relative abundance of AOB was 18.7%, denitrifying bacteria was 15%, NOB < 1%, and filamentous bacteria < 1%, as shown in Table 1 and Figure 2 shown.

[0047] Ammonia monooxygenase AMO is the enzyme activity of microorganisms to oxidize ammonia nitrogen to nitrous oxide, which reflects the rate of ammonia nitrogen oxidation and is an indicator of the activity of cultured bacteria; while oxidoreductase HAO is the enzyme activity of hydroxylamine, which is an intermediate product of ammonia nitrogen oxidation to nitrous oxide, and is also an indicator of the activity of cultured bacteria. During the entire operation stage, ammonia monooxygenase AMO and hydroxylamine oxidoreductase HAO continued to increase (such as Figure 5 At the end of the stage, the NAR increased to 0.10 μg nitrous oxide / (mg protein·min) and 6.39 EU / g SS, respectively. After more than 30 days of continuous stable operation, the NAR remained above 95%, as shown in Figure 3 shown.

[0048] Example 2

[0049] The method of this embodiment for achieving rapid accumulation of nitrous oxide by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora includes four stages, which are respectively recorded as P0 stage, P1 stage, P2 stage and P3 stage. The specific operation steps are as follows:

[0050] In the P0 stage, the return sludge from the secondary sedimentation tank of the municipal sewage plant was starved for 10 days under anoxic conditions. No substrate was provided during the culture period, and no reaction conditions were controlled. It was only left to stand in the laboratory. Through starvation culture, on the one hand, the residual substrate in the sludge was degraded, and on the other hand, heterotrophic microorganisms were eliminated. At the same time, AOB and NOB were inhibited to different degrees by their different tolerance to starvation. After anoxic starvation culture, the relative abundance of AOB was 0.1%, the relative abundance of NOB was 0.1%, and the abundance of filamentous fungi Candidatus_Microthrix was 40%.

[0051] After the anoxic starvation culture stage, the P1 stage was entered. In this stage, artificially prepared wastewater was added to the reactor. The ammonia nitrogen concentration in the wastewater was 50 mg / L, the nitrous acid concentration was 0 mg / L, the nitrate nitrogen concentration was 5 mg / L, the COD was 0 mg / L, and the ammonia nitrogen / nitrate nitrogen ratio in the influent was 10. Aeration culture was performed, and the aeration volume was controlled to be 0.01 L / h / kg ammonia nitrogen, and gradually increased at a growth rate of 0.005, so that DO was around 0.8 mg / L; the alkalinity was 2000 mg / L, and the FA was 11.5 mg / L; the aeration time was set to 10 h, and the water exchange ratio was 65%. After 19 days of operation, the relative abundance of AOB increased to 5%, the relative abundance of NOB was <1%, and the filamentous fungus Candidatus_Microthrix was reduced to 25%.

[0052] In the P2 stage, the aeration volume and other conditions were kept constant, and the system was operated continuously for 28 days. Nitrous acid accumulated stably, and the nitrous acid accumulation rate was >90%. Anoxic starvation culture was carried out again for 12 days to increase the secretion of extracellular polymers and soluble microbial products, thereby inducing short-range denitrifiers. After that, the relative abundance of AOB increased to 27%, and the relative abundance of NOB was <1%. The endogenous short-range denitrifiers included Arenimonas, OLB8 and Truepera, and the sum of their relative abundances was 13%. After anoxic starvation, the system was operated continuously for 32 days, and NAR was >95%.

[0053] In the P3 stage, the reactor was switched to aerobic operation again, and the aeration rate was maintained at 0.007L / h / kg ammonia nitrogen. A membrane module was added to the reactor, and the membrane module was a hollow fiber membrane. The reactor was switched to continuous flow MBR operation, and the hydraulic retention time HRT was controlled to 10h, and the sludge age SRT was controlled to 50 days. At the same time, SRT / HRT>100, the sludge concentration was 8000mg / L, the soluble microbial products were 110mg / L, and the extracellular polymers were 22mg / g SS, providing an endogenous carbon source for short-range denitrification; the relative abundance of AOB was 16%, the denitrifying bacteria was 17%, NOB<1%, and the filamentous bacteria<1%. After continuous and stable operation for more than 30 days, NAR was always maintained above 95%.

[0054] The changes of nitrogen concentration and nitrous acid accumulation rate at each stage are as follows Figure 6 shown.

[0055] Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial communities, characterized in that: The following steps are involved: (1) Starve the return sludge or excess sludge under anoxic conditions to make the relative abundance of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria ≤ 1% and the relative abundance of filamentous bacteria > 40%; (2) aerating the sludge obtained through starvation culture in step (1) in wastewater in an intermittent operation manner, so that the relative abundance of ammonia oxidizing bacteria is greater than 4%, the relative abundance of nitrite oxidizing bacteria is less than 1%, and the relative abundance of filamentous bacteria is less than 30%; the ammonia nitrogen concentration in the wastewater is 50-400 mg / L, the nitrous acid concentration is 0-5 mg / L, the nitrate nitrogen concentration is 5-50 mg / L, the COD is less than 10 mg / L, and the ammonia nitrogen / nitrate nitrogen ratio is ≥10; (3) the sludge aerated in step (2) is further aerated in the wastewater for 28-40 days, followed by anoxic starvation culture, and then further aerated in the wastewater to achieve a relative abundance of ammonia oxidizing bacteria >20%, a relative abundance of nitrite oxidizing bacteria <1%, and endogenous short-range denitrifying bacteria >10%; (4) The sludge from step (3) is converted to a continuous flow MBR operation, so that the relative abundance of ammonia oxidizing bacteria is greater than 15%, the relative abundance of endogenous short-range denitrifying bacteria is ≥ 15%, the relative abundance of nitrite oxidizing bacteria is less than 1%, and the relative abundance of filamentous bacteria is less than 1%.

2. The method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora according to claim 1, characterized in that: The conditions of aeration culture in step (2) are as follows: aeration volume of 0.005-0.02 L / h / kg ammonia nitrogen, dissolved oxygen of 0.2-1.0 mg / L, free ammonia>10 mg / L, water exchange ratio>60%.

3. The method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora according to claim 1, characterized in that: Step (3) The endogenous short-range denitrifying bacteria include Arenimonas, OLB8, and Truepera.

4. The method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora according to claim 3, characterized in that: The continuous flow MBR operation conditions are as follows: aeration rate of 0.005-0.01 L / h / kg ammonia nitrogen, hydraulic retention time of 4-12 h, sludge age of 50-100 days, sludge age / hydraulic retention time>100.

5. The method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora according to claim 4, characterized in that: In step (4), the sludge concentration is >8000 mg / L, the soluble microbial products are >100 mg / L, and the extracellular polymers are >20 mg / g SS.

6. The method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora according to claim 1, characterized in that: The starvation culture time in step (1) is 7-10 days.

7. The method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora according to claim 1, characterized in that: The aeration culture time in step (2) is 10-20 days.

8. The method for achieving rapid accumulation of nitrous oxide by coupling short-range nitrification and endogenous short-range denitrification with a bacterial community according to claim 1, characterized in that: The duration of the anoxic starvation culture in step (3) is 7-15 days, and then the duration of the aerated culture in the wastewater is 10-40 days.

9. The method for achieving rapid accumulation of nitrous acid by coupling short-range nitrification and endogenous short-range denitrification with bacterial flora according to claim 8, characterized in that: After the starvation culture and aeration culture in step (3), when the relative abundance of the ammonia oxidizing bacteria is less than 20%, the starvation culture and aeration culture are repeated.

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