Two-stage HRBPR-PN / A process and device based on sludge biological enhancement

Abstract

The invention provides a two-stage HRBPR-PN / A process and device based on sludge biological enhancement. In the front section of the process, an endogenous carbon source is taken in and phosphate is released in an anaerobic stage through phosphorus-accumulating bacteria (PAOs), and then excessive phosphorus is absorbed in an aerobic stage. And the rear stage is an anaerobic / aerobic alternate operation short-cut nitrification anaerobic ammonia oxidation (PNA) process, under the condition of low dissolved oxygen, ammonia oxidizing bacteria AOB and anaerobic ammonia oxidizing bacteria AnAOB cooperate to efficiently remove nitrogen, and meanwhile, residual organic matters in the previous stage and nitrate in the system are removed by strengthening endogenous denitrification. The method comprises the following steps: introducing residual sludge containing a small amount of AOB from an HRBPR section, and periodically adding the residual sludge into a PN / A reactor according to a volume ratio of 0.1-5%; according to the process, segmented DO control is adopted, NOB ecological niche inhibition and short-cut nitrification long-term stability are achieved, and synchronous deep nitrogen and phosphorus removal can be achieved without additional carbon sources and chemical agents. The device has the advantages of low energy consumption, low sludge yield, high operation stability and the like, and is suitable for energy-saving and efficient treatment of urban low-C / N-ratio sewage.

Description

Technical Field

[0001] This invention relates to a two-stage process and apparatus for HRBPR-PN / A based on sludge bio-enhanced treatment, belonging to the field of wastewater treatment. Background Technology

[0002] Water resources are fundamental to human survival and sustainable social development. However, with the acceleration of urbanization and industrialization, the generation and discharge of wastewater have increased significantly, with urban domestic sewage accounting for the majority. Domestic sewage is characterized by large volumes and high concentrations of nitrogen and phosphorus. If discharged directly into natural water bodies without effective treatment, it can easily lead to eutrophication and cause serious ecological problems. Therefore, the efficient removal of nitrogen and phosphorus pollutants from domestic sewage is of significant environmental importance.

[0003] Traditional biological nitrogen and phosphorus removal processes use nitrification-denitrification as the core pathway. In this process, the nitrification stage requires a large amount of oxygen, resulting in high energy consumption; while the denitrification stage, due to insufficient carbon sources, usually requires the addition of external organic carbon sources to maintain the reaction, increasing operating costs. In contrast, anammox, as a novel autotrophic nitrogen removal technology, does not require external carbon sources and significantly reduces aeration energy consumption, showing promising engineering application prospects. However, the stable operation of the anammox process depends on a continuous supply of nitrite, and partial nitrification (PN) is considered a key pathway for providing nitrite. The PN / A process, formed by coupling partial nitrification and anammox, has been applied on a large scale in the treatment of high ammonia nitrogen wastewater, but when treating urban domestic sewage under low ammonia nitrogen and low temperature conditions, it still faces problems such as difficulty in anammox bacterial enrichment and unstable nitrite accumulation, especially the difficulty in inhibiting nitrite-oxidizing bacteria (NOB).

[0004] Currently, NOB suppression strategies mainly focus on regulating key operating parameters, such as dissolved oxygen (DO) concentration, sludge retention time (SRT), and free nitrous acid (FNA) concentration, in order to establish a microenvironment in the bioreactor system that is conducive to the growth of ammonia-oxidizing bacteria (AOB) while selectively inhibiting NOB activity. These regulatory methods can typically significantly enhance the selective accumulation of nitrite in short-term operation, providing the necessary precursor conditions for partial nitritation / anammox (PN / A) processes.

[0005] Recent studies have found that residual sludge from biological phosphorus removal reactors can achieve rapid and efficient short-cut nitrification. Based on this, researchers have proposed a new strategy of "simultaneous washing and selective recovery": by operating under conditions of high organic loading (≥300 mgCOD / gVSS / d) and short sludge age (approximately 15 days), simultaneous washing of AOB and NOB is achieved. Subsequently, the organic loading is reduced, allowing AOB to recover rapidly and maintain short-cut nitrification, while NOB activity remains suppressed for a long period.

[0006] Based on the aforementioned research, this study constructed a two-stage HRBPR-PN / A coupled process based on sludge bioaugmentation to achieve simultaneous and efficient removal of nitrogen and phosphorus from urban domestic wastewater. The process begins with an alternating anaerobic / aerobic HRBPR stage for the removal of some organic matter and phosphorus. The subsequent stage is a short-cut nitrification anaerobic ammonium oxidation (PNA) process. Under low dissolved oxygen conditions, ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing bacteria (AnAOB) work synergistically to efficiently remove nitrogen, while simultaneously enhancing endogenous denitrification to remove residual organic matter and nitrates from the previous stage. To ensure the long-term stability of the short-cut nitrification process in the PN / A system, excess sludge from the HRBPR stage containing a small amount of AOB is periodically added to the PN / A reactor at a volume ratio of 0.1%–5%. This coupled process not only reduces operating costs and carbon source dependence, but also achieves sludge reduction and resource utilization, innovatively solving the NOB suppression problem and providing a new path for low-carbon and efficient treatment of urban domestic sewage. Summary of the Invention

[0007] The purpose of this invention is to construct a two-stage HRBPR-PN / A process based on sludge bioaugmentation to achieve simultaneous deep nitrogen and phosphorus removal from municipal wastewater. In the HRBPR stage, phosphorus is primarily removed in an anaerobic / aerobic mode. Polyphosphate-accumulating bacteria store internal carbon sources and release phosphates in the anaerobic stage, while excessive phosphate is absorbed in the aerobic stage, and phosphorus removal is achieved through sludge discharge. In the PN / A stage, the effluent from the HRBPR stage is treated. Under hypoxic conditions, ammonia-oxidizing bacteria (AOB) synergistically with anaerobic ammonia-oxidizing bacteria (AnAOB) achieve nitrogen removal through a short-cut nitrification coupled with anaerobic ammonia oxidation pathway. Simultaneously, enhanced endogenous denitrification removes residual organic matter from the previous stage and nitrates within the system. To ensure the long-term stability of the short-cut nitrification process in the PN / A system, excess sludge from the HRBPR stage containing a small amount of AOB is periodically added to the PN / A reactor at a volume ratio of 0.1%–5%. Through this process, deep nitrogen and phosphorus removal is achieved.

[0008] This solution is achieved through the following technical approach:

[0009] (I) Start-up of the high-efficiency biological phosphorus removal reactor: The high-efficiency biological phosphorus removal reactor (1) is inoculated with nitrified sludge. The influent is urban domestic sewage. The sewage is added to the raw water tank (1.1). The influent pump (1.2) is started to pump the sewage into the high-efficiency biological phosphorus removal reactor (1). Anaerobic stirring is performed for 30-60 min. Then the air pump (1.3) is turned on. The DO concentration is maintained at 2.0-3.0 mg / L by adjusting the gas flow meter (1.4) and monitoring the DO concentration online in real time through the first DO sensor (1.7). Aeration and stirring are performed for 30-60 min. Finally, sedimentation and drainage are performed with a drainage ratio of 0.4-0.6. Sludge needs to be discharged when the high-efficiency biological phosphorus removal reactor (1) is running. The sludge discharge valve (1.9) is opened and the sludge discharge time is controlled so that the sludge concentration in the high-efficiency biological phosphorus removal reactor (1) is maintained in the range of 2000-4000 mg / L. The process involves a 3-10 day SRT (Self-Release Time) to gradually wash away nitrifying bacteria and allow polyphosphate-accumulating bacteria to become dominant. When the effluent COD is less than 100 mg / L and the total phosphorus is less than 0.5 mg / L, the high-efficiency biological phosphorus removal reactor is started up.

[0010] (II) Start-up of the integrated short-cut nitrification anammox reactor: Start the second influent peristaltic pump (2.1) to pump the wastewater from the high-efficiency biological phosphorus removal reactor (1) into the integrated short-cut nitrification anammox reactor (2), and perform anammogenic stirring for 30-60 min; then, perform aeration stirring for 60-300 min, turn on the second air pump (2.2), and adjust the second gas flow meter (2.3) to make the DO concentration in the integrated short-cut nitrification anammox reactor (2) 0.2-1.5 mg / L; finally, perform sedimentation and drainage, with a drainage ratio of 0.4-0.6; the integrated short-cut nitrification anammox reactor (2) needs to be sludge discharged during operation, so turn on the second sludge discharge pump (2.9) and control the sludge discharge time to maintain the sludge concentration in the integrated short-cut nitrification anammox reactor (2) at 2000-4000 mg / L. Within the mg / L range, 0.1%~5% of sludge taken from the sludge storage tank (1.10) is added to the short-cut nitrification-anaerobic ammonium oxidation integrated reactor (2) daily. When the effluent NH4⁺-N and TN continuously and steadily decrease for 7–14 consecutive days, and ΔNO2⁻ / ΔNH4⁺≈1.0–1.5 and ΔNO3⁻ / ΔNH4⁺≈0.1–0.3, the anammox specific activity (SAA) increases significantly and tends to stabilize, and the reactor DO is maintained at 0.2–1.5 mg / L and MLSS is maintained at 2000–4000 mg / L, the short-cut nitrification-anaerobic ammonium oxidation integrated reactor can be judged to have been successfully started up.

[0011] 2) Long-term operation of the reactor

[0012] (I) Operation and control of high-efficiency biological phosphorus removal reactor: Dissolved oxygen (DO): DO is controlled at 2.0-3.0 mg / L during the aerobic stage, and precise control is achieved by linking the air pump and flow meter through an online DO sensor; Sludge retention time (SRT): controlled at 3-10 days; Hydraulic retention time (HRT): 4-6 hours; Anaerobic: the time ratio of the aerobic stage is 1:1; pH and temperature: pH is controlled at 7.0-7.5; temperature is maintained at 20-28 ℃; Sludge concentration: MLSS is controlled within the range of 2000-4000 mg / L.

[0013] (II) Operation control of short-cut nitrification-anaerobic ammonia oxidation reactor: Dissolved oxygen (DO): controlled at 0.2-0.8 mg / L to create a low-oxygen environment that is conducive to AOB growth and inhibits NOB activity; Sludge retention time (SRT): controlled at 20-40 days; Hydraulic retention time (HRT): 6-8 hours, each operating cycle includes anaerobic stirring for 30-60 min, low-oxygen aeration for 120-240 min, and sedimentation for 30 min, with the discharge ratio controlled at 0.4-0.6; pH and temperature: pH maintained at 7.5-8.0, and temperature controlled at 25-30 ℃; Free nitrite (FNA) concentration: by adjusting pH and NO2⁻ concentration, FNA is kept in the range of 0.02-0.2 mg HNO2-N / L; Sludge enhancement strategy: by adding 0.1%-5% of sludge taken from the sludge storage tank (1.10) daily at a volume ratio of 0.1%-5%, the number and activity of AOB in the PN / A stage are increased. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the device of the present invention.

[0015] 1 – High-efficiency biological phosphorus removal reactor; 2 – Short-cut nitrification-anaerobic ammonia oxidation integrated reactor; wherein 1.1 – Inlet tank; 1.2 – First inlet peristaltic pump; 1.3 – First air pump; 1.4 – First gas flow meter; 1.5 – First stirring pump; 1.6 – pH sensor; 1.7 – DO sensor; 1.8 – First outlet pump; 1.9 – First sludge pump; 1.10 – Sludge storage tank; 1.11 – First outlet tank; 2.1 – Second inlet peristaltic pump; 2.2 – Second air pump; 2.3 – Second gas flow meter; 2.4 – Second stirring pump; 2.5 – Second pH sensor; 2.6 – Second dissolved oxygen sensor; 2.7 – Second outlet pump; 2.8 – Second outlet tank; 2.9 – Second sludge pump.

[0016] 1 is the operating mode of a high-efficiency biological phosphorus removal reactor.

[0017] 2 is the operating mode of the short-cut nitrification anaerobic ammonia oxidation integrated reactor. Detailed Implementation

[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] (I) Start-up of the high-efficiency biological phosphorus removal reactor: The high-efficiency biological phosphorus removal reactor (1) is inoculated with nitrified sludge. The influent is urban domestic sewage. The sewage is added to the raw water tank (1.1). The influent pump (1.2) is started to pump the sewage into the high-efficiency biological phosphorus removal reactor (1). Anaerobic stirring is performed for 30-60 min. Then the air pump (1.3) is turned on. The DO concentration is maintained at 2.0-3.0 mg / L by adjusting the gas flow meter (1.4) and monitoring the DO concentration online in real time through the first DO sensor (1.7). Aeration and stirring are performed for 30-60 min. Finally, sedimentation and drainage are performed with a drainage ratio of 0.4-0.6. Sludge needs to be discharged when the high-efficiency biological phosphorus removal reactor (1) is running. The sludge discharge valve (1.9) is opened and the sludge discharge time is controlled so that the sludge concentration in the high-efficiency biological phosphorus removal reactor (1) is maintained in the range of 2000-4000 mg / L. The process involves a 3-10 day SRT (Self-Release Time) to gradually wash away nitrifying bacteria and allow polyphosphate-accumulating bacteria to become dominant. When the effluent COD is less than 100 mg / L and the total phosphorus is less than 0.5 mg / L, the high-efficiency biological phosphorus removal reactor is successfully started up.

[0020] (II) Start-up of the integrated short-cut nitrification anammox reactor: Start the second influent peristaltic pump (2.1) to pump the wastewater from the high-efficiency biological phosphorus removal reactor (1) into the integrated short-cut nitrification anammox reactor (2), and perform anammogenic stirring for 30-60 min; then, perform aeration stirring for 60-300 min, turn on the second air pump (2.2), and adjust the second gas flow meter (2.3) to make the DO concentration in the integrated short-cut nitrification anammox reactor (2) 0.2-1.5 mg / L; finally, perform sedimentation and drainage, with a drainage ratio of 0.4-0.6; the integrated short-cut nitrification anammox reactor (2) needs to be sludge discharged during operation, so turn on the second sludge discharge pump (2.9) and control the sludge discharge time to maintain the sludge concentration in the integrated short-cut nitrification anammox reactor (2) at 2000-4000 mg / L. Within the mg / L range, 0.1%~5% of sludge taken from the sludge storage tank (1.10) is added to the short-cut nitrification-anaerobic ammonium oxidation integrated reactor (2) daily. When the effluent NH4⁺-N and TN continuously and steadily decrease for 7–14 consecutive days, and ΔNO2⁻ / ΔNH4⁺≈1.0–1.5 and ΔNO3⁻ / ΔNH4⁺≈0.1–0.3, the anammox specific activity (SAA) increases significantly and tends to stabilize, and the reactor DO is maintained at 0.2–1.5 mg / L and MLSS is maintained at 2000–4000 mg / L, the short-cut nitrification-anaerobic ammonium oxidation integrated reactor can be judged to have been successfully started up.

[0021] (III) System operating parameters and control strategies

[0022] 1. Operation and Control of High-Efficiency Bioreactor (HRBPR)

[0023] The high-efficiency biological phosphorus removal reactor adopts an alternating anaerobic / aerobic operation mode: Dissolved oxygen (DO): During the aerobic stage, DO is controlled at 2.0–3.0 mg / L, and precise control is achieved through online DO sensors linked to air pumps and flow meters; Sludge retention time (SRT): Controlled at 3–10 days; Hydraulic retention time (HRT): 4–6 hours, with an anaerobic:aerobic time ratio of 1:1; pH and temperature: pH is controlled at 7.0–7.5; temperature is maintained at 20–28 ℃; Sludge concentration: MLSS is controlled within the range of 2000–4000 mg / L to ensure sufficient biomass in the system.

[0024] 2. Operation and Control of Short-Cut Nitrification-Anaerobic Ammonium Oxidation Reactor (PN / A)

[0025] Short-cut nitrification-anaerobic ammonium oxidation reactor: Dissolved oxygen (DO): controlled at 0.2–0.8 mg / L; Sludge retention time (SRT): controlled at 20–40 days to ensure stable enrichment of anaerobic ammonium oxidizing bacteria (AnAOB); Hydraulic retention time (HRT): 6–8 hours, each operating cycle includes anaerobic stirring for 30–60 min, low-oxygen aeration for 120–240 min, and sedimentation for 30 min, with a effluent ratio controlled at 0.4–0.6; pH and temperature: pH maintained at 7.5–8.0, and temperature controlled at 25–30 ℃; Free nitrite (FNA) concentration: by adjusting pH and NO₂⁻ concentration, FNA is maintained in the range of 0.02–0.2 mg HNO₂-N / L; Sludge enhancement strategy: by adding 0.1%–5% of excess sludge from the HRBPR stage daily, the number and activity of AOBs in the PN / A stage are increased.

[0026] This patent applies to the treatment of urban sewage. In a specific example, the urban sewage used comes from a septic tank in a residential area of ​​Beijing, with the following water quality indicators: COD concentration of 198–400 mg / L, NH4+ concentration of... + -N concentration is 40–80 mg / L, NO2 - -N concentration <0.5 mg / L, NO3 - -N concentration <1 mg / L, P concentration 4.2~8.4 mg / L, C / N ratio average 4, belonging to low C / N ratio wastewater. The seed sludge required for the high-efficiency biological phosphorus removal reactor (1) comes from traditional activated sludge from a municipal wastewater treatment plant in Beijing, and the seed sludge required for the short-cut nitrification-anaerobic ammonia oxidation integrated reactor (2) comes from sludge in the PN / A system. The system devices are as follows: Figure 1As shown, the high-efficiency biological phosphorus removal reactor (1) and the short-cut nitrification anaerobic ammonia oxidation integrated reactor (2) are made of plexiglass with an effective volume of 10 L.

[0027] The advantages of this invention are:

[0028] (1) Segmented DO control to achieve NOB niche inhibition and long-term stability of short-range nitrification.

[0029] This invention employs a high-DO and low-DO staged operation strategy in a high-efficiency biological phosphorus removal reactor (HRBPR) and a short-cut nitrification-anaerobic ammonium oxidation reactor (PN / A), respectively. The initial DO level is maintained at 2.0–3.0 mg / L to enhance polyphosphate-accumulating bacteria activity and wash away nitrifying bacteria, while the final DO level is controlled at 0.2–0.8 mg / L to create a growth environment favorable to ammonia-accumulating bacteria (AOB) but unfavorable to nitrogen oxides (NOB). Compared to the traditional PN / A process where the DO level in a single reactor is controlled above 1.0 mg / L, this invention effectively avoids the problem of competitive recovery of NOB through spatial separation and niche regulation, significantly extending the stable operation cycle of short-cut nitrification.

[0030] (2) Sludge enhancement strategy to improve system resilience and microbial structure stability.

[0031] This invention utilizes AOB sludge enriched in the upstream HRBPR reactor, which is periodically added to the PN / A reactor at a volume ratio of 0.1% to 5%. Unlike traditional PN / A processes that require prolonged external acclimatization or supplementary inoculation, this strategy dynamically maintains the dominant AOB community during system operation and enhances the system's ability to cope with temperature fluctuations and organic matter disturbances, significantly shortening the start-up period and improving engineering applicability.

[0032] (3) Significantly reduces operating costs and adapts to low C / N wastewater conditions.

[0033] This invention achieves simultaneous deep nitrogen and phosphorus removal through endogenous sludge enhancement and precise parameter control, without the need for external carbon sources or chemical agents. Compared with existing biological denitrification processes that rely on external carbon sources, it has advantages such as low energy consumption, low sludge production, and strong operational stability, making it particularly suitable for energy-efficient treatment of urban wastewater with low C / N ratios.

Claims

1. A two-stage HRBPR-PN / A device based on sludge bio-enhanced treatment, characterized in that: The device includes an inlet system, a high-efficiency biological phosphorus removal reaction system, and a short-cut nitrification-anaerobic ammonia oxidation integrated reaction system connected in sequence. The inlet system includes an inlet tank (1.1) and a first inlet peristaltic pump (1.2) for pumping urban sewage stably into the high-efficiency biological phosphorus removal reactor. The reactor is equipped with a first stirrer (1.5), a first pH probe (1.6), and a first dissolved oxygen probe (1.7) to maintain uniform mixing and monitor reaction parameters in real time. An aeration device is provided at the bottom of the reactor, supplied with air by a first air pump (1.3) and controlled by a first gas flow meter (1.4). An overflow port and an exhaust device are provided at the top of the reactor. The effluent from (1) is pumped by the first effluent pump. (1.8) is transported to (2), and excess sludge is discharged into the sludge storage tank (1.10) through the first sludge discharge pump (1.9) to realize the regulation and recycling of sludge concentration in the system; (2) is a short-cut nitrification-anaerobic ammonia oxidation integrated reactor, with a second air pump (2.2) installed on its top, and the aeration rate is controlled by the second gas flow meter (2.3); a second stirring pump (2.4) is installed inside to keep the liquid phase mixed evenly; a second pH sensor (2.5) and a second dissolved oxygen sensor (2.6) are installed in the reactor to monitor the reaction environment online; the effluent from the second reactor (2) is discharged into the second effluent tank (2.8) through the second effluent pump (2.7) to collect the treated water sample; A second sludge pump (2.9) is installed at the bottom of the reactor for periodically discharging excess sludge.

2. The method of using the apparatus as described in claim 1, characterized in that, Includes the following steps: 1) System startup: Its characteristics include the following: (I) Start-up of the high-efficiency biological phosphorus removal reactor: The high-efficiency biological phosphorus removal reactor (1) is inoculated with nitrified sludge. The influent is urban domestic sewage. The sewage is added to the influent tank (1.1). The first influent peristaltic pump (1.2) is started to pump the sewage into the high-efficiency biological phosphorus removal reactor (1). Anaerobic stirring is carried out for 30-60 minutes. Then the first air pump (1.3) is turned on. The first gas flow meter (1.4) is adjusted and the DO concentration is monitored online in real time through the first DO sensor (1.7) to maintain the DO concentration at 2.0-3.0 mg / L. Aeration and stirring are carried out for 30-60 minutes; finally, sedimentation and drainage are carried out, with a drainage ratio of 0.4-0.6; when the high-efficiency biological phosphorus removal reactor (1) is running, sludge needs to be discharged. The sludge discharge valve (1.9) is opened and the sludge discharge time is controlled so that the sludge concentration in the high-efficiency biological phosphorus removal reactor (1) is maintained in the range of 2000-4000 mg / L; and nitrifying bacteria are gradually washed over with SRT for 3-10 days so that polyphosphate-accumulating bacteria become dominant; when the effluent COD is less than 100 mg / L and the total phosphorus is less than 0.5 mg / L, the high-efficiency biological phosphorus removal reactor is started up. (II) Start-up of the integrated short-cut nitrification anaerobic ammonium oxidation reactor: Start the second inlet peristaltic pump (2.1) to pump the drainage from the high-efficiency biological phosphorus removal reactor (1) into the integrated short-cut nitrification anaerobic ammonium oxidation reactor (2), and anaerobic stirring for 30-60 min; then, aerate and stir for 60-300 min, turn on the second air pump (2.2), and adjust the second gas flow meter (2.3) to make the DO concentration in the integrated short-cut nitrification anaerobic ammonium oxidation reactor (2) 0.2-1.5 mg / L; Finally, sedimentation and drainage are carried out, with a drainage ratio of 0.4 to 0.

6. When the short-cut nitrification anammox integrated reactor (2) is running, sludge needs to be discharged. The second sludge discharge pump (2.9) is turned on and the sludge discharge time is controlled so that the sludge concentration in the short-cut nitrification anammox integrated reactor (2) is maintained in the range of 2000 to 4000 mg / L. 0.1% to 5% of sludge taken from the sludge storage tank (1.10) is added to the short-cut nitrification anammox integrated reactor (2) every day. When the effluent NH4 + -N and TN continued to decrease steadily and ΔNO2 - / ΔNH4 + ≈1.0–1.5, ΔNO3 - / ΔNH4 + The specific activity of anammox increased significantly and tended to stabilize when the DO in the reactor was maintained at 0.2–1.5 mg / L and the MLSS was maintained at 2000–4000 mg / L. The short-cut nitrification-anammox integrated reactor was considered to have been successfully started up. 2) Long-term operation of the reactor (I) Operation and control of the high-efficiency biological phosphorus removal reactor: The high-efficiency biological phosphorus removal reactor adopts an alternating anaerobic / aerobic operation mode: Dissolved oxygen (DO) in the aerobic stage is controlled at 2.0-3.0 mg / L, and precise control is achieved by linking the air pump and flow meter through an online DO sensor; Sludge retention time (SRT): controlled at 3-10 days; Hydraulic retention time (HRT): 4-6 hours; Anaerobic: aerobic stage time ratio of 1:1; pH and temperature: pH controlled at 7.0-7.5; temperature maintained at 20-28℃; Sludge concentration: MLSS controlled within the range of 2000-4000 mg / L. (II) Operation and control of the short-cut nitrification-anaerobic ammonium oxidation reactor: Dissolved oxygen is controlled at 0.2–0.8 mg / L to create a low-oxygen environment conducive to AOB growth and inhibiting NOB activity; Sludge retention time (SRT): controlled at 20–40 days to ensure stable enrichment of anaerobic ammonium oxidizing bacteria (AnAOB); Hydraulic retention time (HRT): 6–8 hours, each operating cycle includes anaerobic stirring for 30–60 min, low-oxygen aeration for 120–240 min, and sedimentation for 30 min, with a effluent ratio controlled at 0.4–0.6; pH and temperature: pH is maintained at 7.5–8.0, and temperature is controlled at 25–30℃; Free nitrite (FNA) concentration: controlled by adjusting pH and NO2. - Concentration, keeping FNA in the range of 0.02-0.2 mg HNO2-N / L; sludge enhancement strategy: adding sludge taken from the sludge storage tank (1.10) daily at a rate of 0.1% to 5% of the volume of the short-cut nitrification-anaerobic ammonium oxidation reactor.

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