A short-term nitrification long-term non-sludge discharge stable control nitrite oxidizing bacteria operation strategy

Abstract

The present application relates to sewage biological treatment technology field, disclose a kind of short-cut nitrification long-term no sludge stable control nitrite oxidation bacteria operation strategy.This strategy uses high concentration inoculation sludge by anaerobic fermentation, fast sludge discharge, sludge is repopulated to realize short-cut nitrification start, obtain high activity AOB sludge;By retaining / inoculating predatory microorganism, combined with anaerobic hydrolysis to destroy biofilm, trace element strengthens predatory effect, realize long-term accurate control to NOB under no sludge condition;While regulating and controlling DO, FA and other environmental factors, maintain the dominant position of AOB.The present application can realize short-cut nitrification reactor 400d above no sludge stable operation, AOB abundance is stably above 30%, nitrite accumulation rate maintains above 90%, NOB abundance is controlled below 0.01% and activity is difficult to detect;With the characteristics of simple operation, economic and efficient, strong impact resistance, adapt to low carbon nitrogen ratio municipal sewage denitrification, can be coupled with anaerobic ammonia oxidation process to realize efficient denitrification, suitable for existing water plant original transformation.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment technology, specifically involving an operational strategy for short-cut nitrification with long-term non-sludge discharge and stable control of nitrite-oxidizing bacteria. It is suitable for denitrification treatment of urban wastewater with low carbon-to-nitrogen ratio and can be coupled with anaerobic ammonia oxidation process to form PN / A process, achieving high-efficiency denitrification with low energy consumption and no carbon source. Background Technology

[0002] With the increasing volume of urban wastewater discharge, its characteristics of insufficient carbon sources and high nitrogen and phosphorus content are becoming increasingly prominent. Conventional biological denitrification processes require the complete oxidation of NH4+-N to NO3--N before denitrification, resulting in high aeration energy consumption, large carbon source consumption, and high operating costs. The PN / A process, which couples short-cut nitrification with anaerobic ammonia oxidation, only oxidizes NH4+-N to NO2--N, which then reacts with anaerobic ammonia oxidizing bacteria to generate N2. This saves 50% of aeration energy consumption and requires no external carbon source, making it the preferred process for denitrification of wastewater with a low carbon-to-nitrogen ratio.

[0003] However, the industrial application of the PN / A process is limited by the long-term stability of short-cut nitrification. The core bottleneck is the effective inhibition and control of nitrite-oxidizing bacteria (NOB). Existing short-cut nitrification start-up processes mostly wash NOB by controlling sludge age, DO, FA / FNA, etc., but there are many defects: 1) Continuous large-scale sludge discharge can easily lead to a decrease in sludge concentration, slow growth of ammonia-oxidizing bacteria (AOB), and limited abundance; 2) Low DO control can easily lead to limited nitrification activity, and the system is prone to sludge bulking, resulting in sludge loss; 3) The long-term effect of FA / FNA pretreatment is limited, and adding agents will increase operating costs and introduce additional pollutants; 4) NOB generated in the sewage pipeline continuously invades the reactor with the influent, and existing processes lack effective means of subsequent NOB control, which can easily lead to reactor instability and a sharp drop in nitrite accumulation rate.

[0004] While anaerobic pretreatment combined with rapid sludge removal can economically and effectively achieve nitrite accumulation, it still suffers from low AOB activity and uncontrolled enrichment after NOB intrusion. Therefore, developing a short-cut nitrification operation strategy that does not require long-term sludge removal, can actively control NOB proliferation, and is resistant to exogenous NOB intrusion has become crucial for the industrial application of the PN / A process. Summary of the Invention

[0005] To address the technical shortcomings of existing short-cut nitrification processes, this invention provides an operational strategy for long-term, non-sludge-discharge, stable control of nitrite-oxidizing bacteria in short-cut nitrification. This strategy enables long-term stable operation of short-cut nitrification under non-sludge-discharge conditions, solving the problems of exogenous NOB intrusion, NOB resurgence and proliferation, and AOB abundance limitation caused by long-term sludge discharge. Simultaneously, it yields high-abundance, high-activity AOB sludge, providing a stable nitrite source for the PN / A process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge, comprising the following steps: (1) High-concentration sludge inoculation and anaerobic fermentation pretreatment: Aerobic sludge from the A2O process of urban sewage treatment plant was used as the main inoculated sludge, and anaerobic fermentation acid-producing sludge was added. After 24 hours of natural sedimentation and aeration, the concentration of inoculated sludge in the reactor was controlled at 8~8.5 g / L, and the filling ratio was 100%. A local hypoxic environment was maintained by micro-aeration, and DO was controlled at 0.2 mg / L. Combined with the addition / non-addition of ammonia nitrogen matrix, AOB retention and NOB initial inhibition were achieved. At the same time, the organic matter produced by sludge hydrolysis and the large number of bacteria (prey) released by lysis ensured the survival of predatory microorganisms. (2) Rapid sludge discharge and sludge screening: Shorten the settling time to 20-40 min to discharge sludge fragments with poor settling performance, manually remove expanded sludge and sludge foam, control the sludge age to be less than 7 days, until nitrates in the effluent disappear and nitrite accumulation rate exceeds 90%; (3) Sludge re-proliferation and AOB enrichment: Stop sludge discharge, control DO=0.2-0.5mg / L, maintain the free ammonia (FA) inhibition environment in the reactor by regulating NH4+-N in the effluent, achieve selective AOB proliferation, and repeat the re-proliferation process 1-2 times to make AOB abundance exceed 40%; (4) Long-term stable operation without sludge discharge: Maintain a low DO and FA inhibition environment in the reactor, control NOB proliferation by utilizing the predatory behavior of predatory microorganisms, and decompose sludge EPS and biofilm by anaerobic hydrolytic bacteria to keep the sludge in a flocculent state for a long time and prevent NOB from forming a shelter. (5) Emergency control of exogenous NOB invasion: When the NOB abundance in the reactor increases, the NOB control effect can be quickly restored by adding artificially cultured predatory microorganisms, increasing the anaerobic treatment section, and removing biofilm.

[0007] Furthermore, the actual concentration of the high-concentration inoculated sludge in step (1) is higher than 8 g / L, and the initial SV30 is greater than 50%; the anaerobic fermentation pretreatment stage adopts the method of sludge endogenous respiration oxygen consumption + micro-aeration to make the reactor DO close to 0 mg / L, promote sludge pyrolysis and endogenous respiration, and at the same time realize the proliferation of predatory microorganisms.

[0008] Furthermore, the predatory microorganisms mentioned in steps (1) and (4) include predatory bacteria, protozoa, and metazoa. The predatory bacteria are one or more of myxobacteria, Micavibrio, and Bdellovibrio, while the protozoa and metazoa are nematodes and rotifers that target sludge microparticles / flocs. The predatory microorganisms are either pre-existing in the sludge or artificially inoculated and cultivated, and their abundance is maintained at around 0.1% during stable operation of the reactor.

[0009] Furthermore, the entire process adopts a sequencing batch reactor (SBR). The reactor operates for 4-6 cycles per day. Each cycle includes 10 minutes of influent, 35 hours of aerobic stirring, 20-40 minutes of sedimentation, 10 minutes of effluent discharge, and 10 minutes of idle time. The influent volume is 40% of the effective volume of the reactor. Ammonia nitrogen, sodium bicarbonate, and trace elements are added to the influent, and the NH4+-N concentration is controlled at 150-200 mg / L.

[0010] Furthermore, the trace elements in the influent include one or more of zinc ions, manganese ions, molybdenum ions, cobalt ions, and copper ions. The trace elements are added in the form of nutrient solutions. Nutrient solution I consists of EDTA 5 g / L + FeSO4 9.14 g / L, and nutrient solution II consists of ZnSO4·7H2O 0.43 g / L + CoCl2·6H2O 0.24 g / L + MnCl2·4H2O 0.99 g / L + CuSO4·5H2O 0.25 g / L + NaMoO4·2H2O 0.22 g / L + NiCl2·6H2O 0.19 g / L + NaSeO4·10H2O 0.21 g / L + H3BO3 0.01 g / L. The addition volume of nutrient solutions I and II is 1 ml / L, which is used to enhance the predatory function of predatory microorganisms and limit the mobility of NOB.

[0011] Furthermore, in step (4), the low DO environment control DO≤0.2mg / L is achieved by using a microporous aeration disc combined with a gas rotor flow meter to adjust the aeration volume and realize the gradient control of dissolved oxygen distribution in the reactor; the FA inhibition environment is achieved by controlling the NH4+-N concentration in the effluent to be higher than 40mg / L, and intermittent aeration can be used to further inhibit NOB growth.

[0012] Furthermore, the anaerobic hydrolytic bacteria mentioned in step (4) are anaerobic fermentation acid-producing bacteria inoculated in sludge. They can metabolize polysaccharides and proteins in microbial EPS, destroy the biofilm shelter of NOB, and at the same time maintain the flocculent morphology of sludge through the moderate proliferation of heterotrophic bacteria, thus avoiding a decline in sludge settling performance.

[0013] Furthermore, in step (5), the predatory microorganisms artificially cultivated are screened out using the whole process nitrified sludge as the cultivation substrate to select species that have a preference for predation on NOB; the addition of the anaerobic treatment section is to add an anaerobic stirring stage in the reactor operation cycle, or to carry out centralized anaerobic fermentation treatment on the reactor to further decompose the biofilm and organic particles.

[0014] Furthermore, during stable operation of the reactor, the concentrations of dissolved oxygen, pH, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen are monitored in real time. By adjusting the influent ammonia nitrogen load, aeration rate, and sodium bicarbonate dosage, precise control of DO, FA, and pH can be achieved. The sodium bicarbonate dosage is 3~4 g / L.

[0015] Furthermore, this strategy is adapted to denitrification treatment of urban wastewater with low carbon-to-nitrogen ratios and can be coupled with the anammox process. The effluent from the SBR reactor can be directly pumped into the anammox reactor to achieve efficient denitrification. During coupling, the ratio of nitrite nitrogen to ammonia nitrogen in the effluent from the short-cut nitrification reactor is kept stable. A small amount of short-cut nitrification sludge can be introduced into the anammox reactor to maintain a low DO environment, which helps the anammox reaction to proceed.

[0016] This invention provides an operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge, which has the following beneficial effects: 1. Achieve stable operation without sludge discharge for a long period of time: Breaking through the limitation of existing processes that require long-term sludge discharge and NOB washing, the reactor can achieve stable operation without sludge discharge for more than 400 days, avoiding the limitation of AOB abundance and sludge loss caused by sludge discharge, reducing infrastructure investment and operating costs, and is suitable for on-site renovation of existing water plants.

[0017] AOB activity and abundance are significantly improved: Through high-concentration sludge start-up and sludge re-proliferation, the AOB abundance is stabilized at over 30% (up to over 50%), the short-cut nitrification activity reaches 202 mgN / gMLVSS·h, which is 10 times that of similar processes, and the volumetric activity can reach 128 gN / m3·h, reducing the actual operation requirements for hydraulic retention time (HRT).

[0018] NOB achieves precise and long-term control: Combining the triple NOB control mechanism of predatory microorganisms' preferred predation + FA / DO synergistic inhibition + anaerobic hydrolysis destroying the sanctuary, the NOB abundance is controlled below 0.01%, and NOB activity is difficult to detect (long-term below 0.5 mg N / g(VSS)·h), and it can effectively cope with the invasion of exogenous NOB, and the reactor has strong shock resistance.

[0019] Simple to operate and cost-effective: The entire process does not require the addition of additional chemical agents. It can be achieved through simple operations such as stirring, aeration, sludge discharge, manual removal of floating sludge and foam, and addition of trace elements. Microporous aeration discs are used to precisely control oxygen, saving aeration energy consumption. The inoculated sludge is conventional A2O aerobic sludge from urban wastewater treatment plants, which does not require special screening and the raw materials are readily available.

[0020] Adaptable to PN / A process coupling: It can stably provide influent with a high proportion of nitrite for anaerobic ammonia oxidation process, and the ratio of nitrite nitrogen to ammonia nitrogen in the effluent is controllable. A small amount of short-cut nitrification sludge entering the anaerobic ammonia oxidation reactor can maintain a low DO environment and help the anaerobic ammonia oxidation reaction to proceed. After coupling, it can achieve low energy consumption, high efficiency nitrogen removal without carbon source for wastewater with low carbon-to-nitrogen ratio, and the nitrite accumulation rate is always maintained above 90%.

[0021] High resilience: The enriched, high-abundance AOB sludge exhibits strong resistance to adverse environments such as FA inhibition, FNA inhibition, low DO, low temperature, and low alkalinity. It maintains treatment effectiveness even after operation in harmful environments, and the non-sludge discharge operation allows AOB to quickly recover its activity. The survival of predatory bacteria can be ensured by adding NOB or utilizing organic matter, maintaining predation activity long-term and achieving NOB control. Attached Figure Description

[0022] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the short-path nitration SBR reactor device of the present invention; Figure 2 This diagram illustrates the startup of the short-cut nitrification process of the present invention after anaerobic fermentation pretreatment, as well as the rapid sludge discharge and sludge re-proliferation startup. Figure 3 This is a diagram showing the differences between groups of predatory bacterial gene set flagella assembly metabolic pathways in this invention; Figure 4 This is a diagram showing the differences between groups of metabolic pathways in the bacterial secretion system of the predator gene set of this invention.

[0024] name: Figure 1In the middle section, 1-inlet tank, 2-short-range nitrification SBR reactor, 3-DO / pH meter, 3-1-DO / pH meter display screen, 4-DO probe, 5-pH probe, 5-1-pH probe detection end, 5-2-DO probe detection end, 6-time control switch, 7-constant temperature water bath, 8-inlet pump, 9-drain pump, 10-agitator, 11-aeration pump, 12-gas rotor flow meter, 13-microporous aeration disc. Detailed Implementation

[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1: Construction and Start-up of a Short-Cut Nitrification SBR Reactor 1. Reactor setup A cylindrical sequencing batch reactor (SBR) with an effective volume of 5L is adopted. Made of glass, it features an outer circulating constant-temperature water bath 7 to control the reactor's operating temperature between 22 and 33°C. A microporous aeration disc 13 is installed at the bottom of the reactor, and the aeration rate is adjusted via an aeration pump 11 and a gas rotor flow meter 12. A DO probe 4 and a pH probe 5 are installed inside the reactor, connected to a DO / pH meter 3 to monitor water quality indicators in real time. The influent pump 8, drain pump 9, agitator 10, and aeration pump 11 are all automatically controlled by a timer switch 6, achieving automated operation of influent, agitation, aeration, and drainage. The device structure is shown in [details omitted]. Figure 1 .

[0028] Inoculation sludge and anaerobic fermentation pretreatment The inoculated sludge was aerobic sludge from the A2O process of a municipal wastewater treatment plant. 10% of anaerobic fermentation acid-producing sludge was added. After 24 hours of natural sedimentation, the dense sludge was taken and aerated for 2 hours. The concentration of inoculated sludge in the reactor was controlled at 8.2 g / L, the filling ratio was 100%, and the initial SV30 was 55%.

[0029] The anaerobic fermentation stage utilizes sludge endogenous respiration oxygen consumption + micro-aeration, controlling DO=0.2mg / L (0 mg / L when sludge concentration is high, controlled at 0.2mg / L after startup), without adding ammonia nitrogen substrate, to achieve complete elimination of NOB; this stage runs for 7 days, during which sludge undergoes lysis and endogenous respiration, and predatory microorganisms and anaerobic hydrolytic bacteria proliferate in the reactor.

[0030] Rapid sludge removal and sludge screening The sludge settling time was shortened to 20 minutes. Sludge fragments with poor settling performance were discharged daily. Expanded sludge and foam on the reactor surface were manually removed with a fine mesh net, and the sludge age was controlled at 5 days. This stage was run for 10 days until the nitrate concentration in the reactor effluent was lower than 10 mg / L and the nitrite accumulation rate was 92%, thus completing the initial NOB washing.

[0031] Sludge re-proliferation and AOB enrichment Manual sludge removal was stopped, and DO was controlled at 0.3 mg / L. The effluent NH4+-N was adjusted to 45 mg / L by adjusting the influent ammonia nitrogen load, thus maintaining a FA-inhibiting environment. After 20 days of operation in the sludge re-proliferation phase, AOB abundance increased to 42%, and short-cut nitrification activity reached 105 mgN / gMLVSS·h. The re-proliferation process was repeated once (sludge removal was briefly carried out until the sludge concentration reached 0.8 g / L, after which sludge removal was stopped). After re-proliferation, AOB abundance was 48%, and short-cut nitrification activity was 186 mgN / gMLVSS·h.

[0032] Example 2: Long-term stable operation of a short-cut nitrification reactor without sludge discharge 1. Operating parameter control The reactor entered a long-term operation phase without sludge discharge, running four cycles per day. Each cycle consisted of: 10 minutes of influent (2L influent volume, representing 40% of the reactor's effective volume), 4 hours and 50 minutes of aerobic stirring, 30 minutes of sedimentation, 10 minutes of drainage, and 10 minutes of idle time. The influent was artificially prepared simulated wastewater with the following water quality parameters: NH4+-N = 180 mg / L, NaHCO3 = 3.5 g / L, CaCl2·2H2O = 180 mg / L, MgSO4·7H2O = 100 mg / L, nutrient solution I = 1 ml / L, and nutrient solution II = 1 ml / L. Aeration was achieved using microporous aeration discs, with DO controlled at 0.15 mg / L, and a constant temperature water bath maintained at 30℃.

[0033] Water quality and microbiological indicators monitoring The reactor operated continuously without sludge discharge for 400 days, with real-time monitoring of dissolved oxygen, pH, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen concentrations. AOB, NOB, and the abundance of predatory microorganisms were periodically measured. The results are as follows: Water quality indicators: Ammonia nitrogen removal rate is stable at over 85%, nitrite accumulation rate is maintained at 90%~95%, effluent nitrate nitrogen concentration is consistently below 20 mg / L, and NOB activity is difficult to detect (below 0.5 mgN / g(VSS)·h). Microbial indicators: AOB abundance remained stable at 35%-48%, NOB abundance was controlled below 0.01%, and predatory microorganisms (myxobacteria + Micavibrio) abundance remained at 0.08%-0.12%. Sludge morphology: The sludge maintains a flocculent morphology over a long period of time, with SV30 consistently below 10%, and no sludge bulking or foaming occurs.

[0034] Example 3: Coupling experiment with anaerobic ammonium oxidation process The effluent from the stable-running short-cut nitrification SBR reactor in Example 2 was directly pumped into the anammox reactor. The anammox reactor had an effective volume of 10L, was inoculated with anammox sludge, and the temperature was controlled at 30℃ with a hydraulic retention time of 8h.

[0035] After 30 days of coupled operation, the results showed that the NO2--N / NH4+-N ratio in the effluent of the short-cut nitrification reactor remained stable at 1.3~1.5, which is suitable for the substrate ratio of the anammox reaction; the total nitrogen removal rate of the anammox reactor remained stable at over 80%, and the total nitrogen concentration in the effluent was below 20 mg / L, achieving efficient nitrogen removal from wastewater with a low carbon-to-nitrogen ratio, and verifying the good coupling between the present invention and the PN / A process.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An operational strategy for short-cut nitrification with long-term, non-sludge-discharge stable control of nitrite-oxidizing bacteria, characterized in that, Includes the following steps: (1) High-concentration sludge inoculation and anaerobic fermentation pretreatment: Aerobic sludge from the A2O process of urban sewage treatment plant was used as the main inoculation sludge, and anaerobic fermentation acid-producing sludge was added. After 24 hours of natural sedimentation and aeration, the concentration of inoculated sludge in the reactor was controlled at 8~8.5 g / L, and the filling ratio was 100%. A local hypoxic environment was maintained by micro-aeration, and DO was controlled at 0.2 mg / L. Combined with the addition / non-addition of ammonia nitrogen matrix, AOB retention and NOB initial inhibition were achieved, while ensuring the survival of predatory microorganisms. (2) Rapid sludge discharge and sludge screening: Shorten the settling time to 20-40 min to discharge sludge fragments with poor settling performance, manually remove expanded sludge and sludge foam, control the sludge age to be less than 7 days, until nitrates in the effluent disappear and nitrite accumulation rate exceeds 90%; (3) Sludge re-proliferation and AOB enrichment: Sludge discharge is stopped, DO is controlled at 0.2-0.5 mg / L, and the free ammonia (FA) inhibition environment in the reactor is maintained by NH4+-N regulation in the effluent, so as to achieve selective AOB proliferation. The re-proliferation process can be repeated 12 times to make the AOB abundance exceed 40%; (4) Long-term stable operation without sludge discharge: Maintain a low DO and FA inhibition environment in the reactor, control NOB proliferation by utilizing the predatory behavior of predatory microorganisms, and decompose sludge EPS and biofilm by anaerobic hydrolytic bacteria to keep the sludge in a flocculent state for a long time and prevent NOB from forming a shelter. (5) Emergency control of exogenous NOB invasion: When the NOB abundance in the reactor increases, the NOB control effect can be quickly restored by adding artificially cultured predatory microorganisms, increasing the anaerobic treatment section, and removing biofilm.

2. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: In step (1), the actual concentration of the high-concentration inoculated sludge is higher than 8 g / L, and the initial SV30 is greater than 50%. In the anaerobic fermentation pretreatment stage, the sludge endogenous respiration oxygen consumption + micro-aeration method is adopted to make the reactor DO close to 0 mg / L, promote the proliferation of predatory microorganisms, and realize sludge pyrolysis and endogenous respiration.

3. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: The predatory microorganisms mentioned in steps (1) and (4) include predatory bacteria, protozoa and metazoa. The predatory bacteria are one or more of myxobacteria, Micavibrio, and Bdellovibrio. The protozoa and metazoa are nematodes and rotifers that target sludge microparticles / flocs. The predatory microorganisms are either originally retained in the inoculated sludge or artificially inoculated and cultivated. Their abundance is maintained at about 0.1% during stable operation of the reactor.

4. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: The entire process uses a sequencing batch reactor (SBR). The reactor operates for 46 cycles per day. Each cycle includes 10 minutes of influent, 35 hours of aerobic stirring, 20-40 minutes of sedimentation, 10 minutes of effluent discharge, and 10 minutes of idle time. The influent volume is 40% of the effective volume of the reactor. Ammonia nitrogen, sodium bicarbonate, and trace elements are added to the influent, and the NH4+-N concentration is controlled at 150-200 mg / L.

5. The operational strategy for stable control of nitrite-oxidizing bacteria through long-term, non-sludge-discharge short-cut nitrification as described in claim 1 or 4, characterized in that: The trace elements in the influent include one or more of zinc ions, manganese ions, molybdenum ions, cobalt ions, and copper ions. These trace elements are added in the form of nutrient solutions. Nutrient solution I consists of EDTA 5 g / L + FeSO4 9.14 g / L, and nutrient solution II consists of ZnSO4·7H2O 0.43 g / L + CoCl2·6H2O 0.24 g / L + MnCl2·4H2O 0.99 g / L + CuSO4·5H2O 0.25 g / L + NaMoO4·2H2O 0.22 g / L + NiCl2·6H2O 0.19 g / L + NaSeO4·10H2O 0.21 g / L + H3BO3 0.01 g / L. The dosage of both nutrient solutions I and II is 1 ml / L, used to enhance the predatory function of predatory microorganisms and limit the mobility of NOB.

6. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: In step (4), the low DO environment control DO≤0.2mg / L is achieved by using a microporous aeration disc combined with a gas rotor flow meter to adjust the aeration volume and realize the gradient control of dissolved oxygen distribution in the reactor; the FA inhibition environment is achieved by controlling the NH4+-N concentration in the effluent to be higher than 40mg / L, and intermittent aeration can be used to further inhibit NOB growth.

7. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: The anaerobic hydrolytic bacteria mentioned in step (4) are anaerobic fermentation acid-producing bacteria inoculated in sludge. They can metabolize polysaccharides and proteins in microbial EPS, destroy the biofilm shelter of NOB, and at the same time maintain the flocculent morphology of sludge through the moderate proliferation of heterotrophic bacteria, thus avoiding a decline in sludge settling performance.

8. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: The predatory microorganisms artificially cultured in step (5) are selected from species that have a preference for predation on NOB by using the whole process nitrified sludge as the culture substrate; the addition of the anaerobic treatment section is to add an anaerobic stirring stage in the reactor operation cycle, or to carry out centralized anaerobic fermentation treatment on the reactor to further decompose biofilm and organic particles.

9. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: During stable operation of the reactor, the concentrations of dissolved oxygen, pH, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen are monitored in real time. By adjusting the influent ammonia nitrogen load, aeration rate, and sodium bicarbonate dosage, precise control of DO, FA, and pH can be achieved. The sodium bicarbonate dosage is 3~4 g / L.

10. The operational strategy for stable control of nitrite-oxidizing bacteria through short-cut nitrification without sludge discharge as described in claim 1, characterized in that: This strategy is suitable for denitrification treatment of urban wastewater with low carbon-to-nitrogen ratios. It can be coupled with the anammox process, allowing the effluent from the SBR reactor to be directly pumped into the anammox reactor for efficient denitrification. During coupling, the ratio of nitrite to ammonia nitrogen in the effluent from the short-cut nitrification reactor is kept stable. A small amount of short-cut nitrification sludge can be introduced into the anammox reactor to maintain a low DO environment, which helps the anammox reaction to proceed.

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