A method for directional regulation of polyphosphorus bacteria and polysaccharide bacteria for deep denitrification and dephosphorization of low-concentration municipal sewage

Abstract

This invention discloses a method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep nitrogen and phosphorus removal in low-concentration municipal wastewater. In a sequencing batch reactor (SBR), using low-concentration municipal wastewater as the substrate, deep nitrogen and phosphorus removal is achieved by fully utilizing the coupling of PAOs / DPAOs and GAOs / DGAOs in aerobic granular sludge. During the start-up phase, PAOs are rapidly enriched through periodic sludge discharge in an A / O operation mode. During the operation phase, DGAOs are enriched while simultaneously creating conditions for the emergence of DPAOs through A / O / A mode, sludge age control, and dissolved oxygen concentration regulation, while inhibiting NOB and promoting short-cut nitrification and endogenous denitrification. During the system stabilization period, this invention employs a "periodic carbon source multiplication coupled with PO4" approach. 3‑ The concentration control technology and the duration adjustment of the post-anoxic stage achieve a balance in the abundance of PAOs / DPAOs and GAOs / DGAOs. At this point, yellow and white particles coexist in the system, and the aerobic particle structure is stable, enabling simultaneous synergistic removal of carbon, nitrogen, and phosphorus. The method for targeted regulation of PAOs / DPAOs and GAOs / DGAOs provided by this invention can achieve a COD removal rate of over 90% and a TN / TP removal rate of nearly 100% in wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater biological treatment technology, and in particular to a method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep nitrogen and phosphorus removal in low-concentration municipal wastewater. Background Technology

[0002] Given the carbon concentration limitations of municipal wastewater, achieving a balance in biological nitrogen and phosphorus removal remains a challenging task. Endogenous denitrification (DPR) technology is considered a promising treatment technology in recent years, capable of removing nitrogen and phosphorus from wastewater under anoxic conditions driven by the same carbon source. x -N acts as an electron acceptor to absorb phosphorus, thereby achieving simultaneous carbon, nitrogen, and phosphorus removal. Compared to traditional treatment methods, it can significantly reduce operating costs and reduce sludge production by 50%. Therefore, DPR technology has been widely used in municipal wastewater treatment for decades.

[0003] Despite the significant application potential of DPR technology, phosphorus removal often fluctuates in actual municipal wastewater treatment processes. Under low-carbon conditions, competition for carbon sources between polyphosphate-accumulating organisms (PAOs) and polysaccharide-accumulating organisms (GAOs) is inevitable. PAOs rely on volatile fatty acids (VFAs) as their carbon source, and their metabolic activity is inhibited when VFAs are insufficient in low-carbon wastewater. GAOs have a wider range of carbon source adaptability (e.g., they can metabolize complex carbon sources like glucose) and are more likely to dominate under low-carbon conditions, leading to reduced phosphorus release and absorption efficiency. Except for the phosphorus cycle, the metabolic pathways of GAOs are almost identical to those of PAOs. PAOs consume ATP to release phosphorus to absorb VFAs during the anaerobic phase, while GAOs obtain energy by breaking down glycogen without releasing phosphorus, making their metabolic pathway more efficient. Under low-carbon conditions, the rapid proliferation of GAOs further crowds out the living space of PAOs. Once the metabolism of GAOs becomes superior to that of PAOs, the phosphorus removal performance of the system will inevitably be affected, potentially even leading to the failure of the entire system. In addition, the sludge age difference exists during actual operation, which makes it difficult to further improve the system's nitrogen and phosphorus removal efficiency.

[0004] Enhancing the activity of polyphosphate-accumulating organisms (PAOs / DPAOs) has long been considered a key strategy for improving nitrogen and phosphorus removal efficiency in wastewater treatment. However, in practice, if a wastewater treatment system relies primarily on functional bacteria such as denitrifying polyphosphate-removing bacteria (DPAOs), the system may face certain risks. Especially when the concentration of pollutants in the influent fluctuates, the activity and quantity of DPAOs can be significantly affected, potentially leading to a substantial decline in the performance of the entire wastewater treatment system. To address this challenge, researchers have found that appropriately introducing and enriching denitrifying polysaccharide-removing bacteria (DGAOs) can be an effective strategy to enhance system robustness. DGAOs play a crucial role in wastewater treatment systems; they not only help degrade organic matter (C) and nitrogen (N), but also provide additional support when the system is subjected to external disturbances, such as impaired DPAO performance. Specifically, when DPR is affected by various adverse factors, DGAOs in the system can work synergistically with DPAOs to maintain the system's treatment efficiency. This synergistic effect not only helps prevent the collapse of system treatment performance but also ensures that the wastewater treatment process remains relatively stable when faced with fluctuations in influent load.

[0005] The competition between PAOs and GAOs is the core contradiction in nitrogen and phosphorus removal from low-carbon wastewater. The introduction of DPAOs significantly improves carbon source utilization efficiency by integrating denitrification and phosphorus removal functions. By balancing the metabolic relationship between DPAOs and DGAOs, nitrogen and phosphorus removal performance can be synergistically optimized, avoiding system failure caused by excessive competition from single-function microbial communities, and providing a more sustainable solution for low-carbon wastewater treatment. Therefore, how to balance the relationship between DPAOs and DGAOs, fully utilize carbon sources in wastewater, and ensure the stability of nitrogen and phosphorus removal is currently the focus of advanced nitrogen and phosphorus removal in wastewater treatment. Summary of the Invention

[0006] The purpose of this invention is to provide a method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep nitrogen and phosphorus removal in low-concentration municipal wastewater, in order to solve the problems of low organic matter content in the wastewater, unstable influent, inability to balance the relationship between DPAOs and DGAOs, and inability to fully utilize carbon sources in the wastewater, which leads to instability in the wastewater nitrogen and phosphorus removal process.

[0007] To achieve the above objectives, the present invention provides a method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep denitrification and phosphorus removal in low-concentration municipal wastewater. The deep denitrification and phosphorus removal method for wastewater is carried out by a sequencing batch reactor, which includes a sequencing batch reactor and a PLC control system.

[0008] The bottom of the sequencing batch reactor is equipped with a wastewater inlet, a circulating inlet, an aeration head, and a sludge discharge outlet. The top of the sequencing batch reactor is equipped with an overflow outlet and a circulating outlet. The middle of the sequencing batch reactor is equipped with a clean water discharge outlet that meets different volume exchange ratios.

[0009] Municipal sewage in the inlet tank is introduced into the bottom of the sequencing batch reactor (SBR) through the sewage inlet via an inlet peristaltic pump. Gas is introduced into the aeration head at the bottom of the SBR through a pipe via an air pump for aeration. Liquid at the top of the SBR is introduced into the bottom of the SBR through a circulation inlet via a circulation pump. The treated liquid is introduced into the outlet tank through a clean water outlet via an outlet peristaltic pump. The inlet peristaltic pump, air pump, circulation pump, and outlet peristaltic pump are all connected to the PLC control system.

[0010] The single cycle of this invention is 3.0 to 8.0 hours, mainly including the water inlet and anaerobic stage, the aerobic aeration stage, and the anoxic and effluent stage. The water inlet, circulation, aeration and effluent are controlled by a PLC control system. The water inlet, outlet and circulation flow of the sequencing batch reactor are controlled by a peristaltic pump. The upper water is continuously drawn into the bottom by a circulation pump to realize the internal water circulation flow. The bottom aeration is performed by an air pump and the aeration rate is adjusted to ensure that different dissolved oxygen concentrations are achieved in different stages.

[0011] Preferably, a method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep nitrogen and phosphorus removal in low-concentration municipal wastewater includes the following steps:

[0012] S1: System Startup Phase

[0013] The system startup phase adopts an anaerobic / aerobic operation mode, while the sequencing batch reactor operates intermittently, specifically including four steps: influent, circulation, aeration, and effluent. See S11–S14 for detailed operation instructions.

[0014] S11: Water intake stage

[0015] Start the inlet peristaltic pump to introduce municipal sewage from the inlet tank into the bottom of the sequencing batch reactor through the sewage inlet, thus completing the inlet process;

[0016] S12: Cyclic Phase

[0017] After the water intake is completed, the anaerobic circulation stage begins. The circulation pump is turned on to introduce the liquid at the top of the sequencing batch reactor into the bottom of the sequencing batch reactor through the circulation inlet to achieve internal circulation.

[0018] S13: Aeration Stage

[0019] Start the air pump to introduce gas into the aeration head, and adjust the aeration rate of the aeration head through the flow meter. The dissolved oxygen concentration at the end of the aeration stage should not be lower than 6 mg / L.

[0020] S14: Drainage Stage

[0021] Start the peristaltic pump to introduce the treated liquid into the outlet tank through the clean water drain to complete the drainage process;

[0022] The PLC control system enables continuous cyclic operation of S11 to S14. After 15 days of startup, new particles are generated in the sequencing batch reactor. The new particles are light yellow and the sludge age is 10 to 20 days. At this time, the drainage ratio is increased from 50% to 70%.

[0023] S2: Operation Phase

[0024] During the operation phase, an anaerobic / aerobic / anoxic operating mode is adopted. For specific operation details, please refer to S21 to S22.

[0025] S21: The anaerobic and aerobic stages adopt steps S12 and S13, and a post-anoxic stage is added. That is, after aeration is completed, the circulation pump is turned on to introduce the liquid at the top of the sequencing batch reactor into the bottom of the sequencing batch reactor through the circulation inlet to achieve anoxic internal circulation.

[0026] S22:

[0027] When the water discharged from the water purifier drain has PO4 3- When the concentration remains close to 0.5 mg / L for three consecutive days, the anaerobic reaction ends. The peristaltic pump is then started to discharge the supernatant, followed by re-injection of water and initiation of step S21. During re-injection, the COD concentration is increased from 200 mg / L to 400 mg / L within a single cycle. When the PO4 concentration at the end of the anaerobic reaction... 3- When the concentration is below 20 mg / L, the PO4 in the effluent from the water purification outlet 3- Stop the operation when the concentration is below 0.3 mg / L;

[0028] In the aerobic stage, the aeration rate is controlled by a flow meter, and the dissolved oxygen concentration at the end of the aeration stage is not higher than 2.0 mg / L;

[0029] The PLC control system enables continuous cyclic operation of S21 to S22. During the operation phase, the sludge age is controlled to be 30 to 40 days by sludge discharge.

[0030] The above-mentioned method for regulating PO4 in effluent according to the present invention 3- Concentration can be achieved by releasing the supernatant, or by other methods, such as adding chemicals for precipitation.

[0031] Preferably, municipal activated sludge is used as the inoculum sludge, and the concentration of chemical oxygen demand in municipal wastewater is 100-200 mg / L, ammonia nitrogen concentration is 30-60 mg / L, and total phosphorus concentration is 3-8 mg / L.

[0032] Preferably, the sequencing batch reactor uses municipal activated sludge as inoculum sludge with a sludge concentration of 4000 mg / L.

[0033] Preferably, the effective utilization rate of carbon source in the anaerobic stage is over 90%, the COD ratio stored by PAOs and GAOs is 50% and 40% respectively, and the average COD of the effluent is below 20 mg / L.

[0034] Preferably, in step S1, after circulation, the sludge concentration is 3.0-4.0 g / L, basically achieving complete sludge granulation, with a sludge particle size of 0.5-1.0 mm. The system's TN removal rate increases from 36% to 46%, and the TP removal rate increases from 37% to 75%.

[0035] The abundance of PAOs increased from 4.56% to 10.46%, the abundance of GAOs increased from 5.39% to 5.61%, and the abundance of NOB increased from 2.45% to 2.59%.

[0036] Step S2 of the present invention is divided into an initial stage and a stable stage. The initial stage refers to the start of the operation phase, while the stable stage refers to the end of the operation phase, when the operation phase is in a stable state. As the operation phase progresses from the initial stage to the stable stage, the sludge concentration, TN removal rate, TP removal rate, and bacterial abundance all change. Finally, the optimal removal rate and bacterial balance can be achieved in the stable stage.

[0037] Preferably, in the initial stage of step S2, the duration of the anoxic phase is extended by 1.0–2.5 hours. Appropriately extending the duration of subsequent anoxic phases, under conditions of sufficient internal carbon sources, provides suitable conditions for the denitrification and survival of DPAOs and DGAOs, regulates the system pH, and is beneficial for the stability of granular sludge and achieving an abundance balance between the two. Furthermore, by controlling sludge discharge, the sludge retention time (SRT) is set at 35 days. Appropriately extending the SRT, while ensuring efficient phosphorus removal, is one of the key steps in achieving a balance between DPAOs and DGAOs.

[0038] Preferably, in the initial stage of step S2, the sludge concentration is 6.0 g / L, the system TN removal rate increases from 46% to 73%, and the TP removal rate increases from 75% to 84%.

[0039] The abundance of PAOs decreased from 10.46% to 8.99%, the abundance of DPAOs was 3.40%, the abundance of GAOs increased from 5.61% to 16.73%, the abundance of DGAOs was 5.12%, and the abundance of NOB decreased to 0.07%.

[0040] Preferably, during the stabilization period of step S2, when the organic matter content in the influent is low, in order to maintain the stability of nitrogen and phosphorus removal, this invention employs "carbon source multiplication coupled with PO4". 3-"Concentration control technology" involves draining water at the end of the anaerobic reaction, followed by influent (increasing the influent COD concentration from 200 mg / L to 400 mg / L within a single cycle), and initiating an anaerobic / aerobic / anoxic (A / O / A) operating mode. This technology enhances the phosphorus release and internal carbon source storage capacity of PAOs (polyphosphate-accumulating organisms) in the anaerobic stage by periodically increasing the influent COD concentration exponentially. The discharge of phosphorus-rich liquid at the end of the anaerobic reaction regulates the PO4 content within the system. 3- Concentration. Regulation of PO4 3- Methods for determining concentration include releasing the supernatant through the purified water outlet followed by secondary water intake, and adding chemicals for sedimentation. The appropriate phosphate ion concentration (PO4 at the end of anaerobic digestion) is crucial. 3- Concentrations below 20 mg / L help maintain the metabolic driving force of PAOs, thereby weakening the competition of GAOs. This not only stimulates the activity of PAOs, but also achieves selective enhancement of DPAOs, thus achieving a balance between DPAOs and DGAOs.

[0041] Preferably, during the stabilization period in step S2, the sludge particle size is 1.0–2.0 mm, the sludge concentration is 5.0–6.0 g / L, the ratio of yellow to white particles is 3:2, and the system's TN and TP removal rates are nearly 100%.

[0042] The abundance of PAOs increased from 8.99% to 28.37%, the abundance of DPAOs was 33.3%, the abundance of GAOs increased from 16.73% to 35.7%, the abundance of DGAOs was 100%, and NOB was not detected.

[0043] Therefore, the present invention employs the above-described method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep nitrogen and phosphorus removal in low-concentration municipal wastewater, which has the following beneficial effects:

[0044] (1) The present invention can rapidly enrich PAOs and produce two different types of particles, yellow and white, namely granular sludge mainly composed of DGAOs and granular sludge mainly composed of DPAOs. The resulting granular sludge has a compact structure and is not easily disintegrated.

[0045] (2) The method provided by the present invention achieves targeted regulation of the balance of PAOs / GAOs, which increases the abundance of PAOs to 28.37%, the abundance of DPAOs to 33.3%, the abundance of GAOs from 5.39% to 35.7%, the abundance of DGAOs to 100%, and no NOB is detected, thus promoting the possibility of short-cut nitrification and denitrification.

[0046] (3) This invention utilizes in-situ regulation of DPAOs and DGAOs from low-carbon source wastewater, which can avoid the instability caused by COD content fluctuations when treating actual domestic wastewater and ensure good nitrogen and phosphorus removal capabilities.

[0047] (4) Based on carbon source multiplication technology, this invention is conducive to enriching slow-growing microorganisms, realizing "one carbon for two uses", enhancing the ability of low carbon source wastewater to remove nitrogen and phosphorus, and providing a new idea for simultaneous nitrogen and phosphorus removal.

[0048] (5) The device of the present invention has a small footprint, low energy consumption, and small sludge production, and the system has a nitrogen and phosphorus removal rate of nearly 100%.

[0049] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of a sequencing batch reactor.

[0051] Figure 2 An image showing the appearance of sludge particles during stable operation;

[0052] In the diagram: 1. Sequencing batch reactor; 2. PLC control system; 3. Inlet tank; 4. Outlet tank; 1.1. Flow meter; 1.2. Air pump; 1.3. Aerator head; 1.4. Inlet peristaltic pump; 1.5. Wastewater inlet; 1.6. Clean water outlet one; 1.7. Outlet peristaltic pump; 1.8. Clean water outlet two; 1.9. Sludge outlet; 1.10. Circulation pump; 1.11. Circulation outlet; 1.12. Circulation inlet; 1.13. Overflow outlet. Detailed Implementation

[0053] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0054] Example 1

[0055] A device for deep nitrogen and phosphorus removal in low-concentration municipal wastewater has the following specific structure:

[0056] The method for deep nitrogen and phosphorus removal from wastewater is carried out by a sequencing batch reactor (SBR), which includes a sequencing batch reactor 1 and a PLC control system 2.

[0057] The bottom of the sequencing batch reactor 1 is provided with a wastewater inlet 1.5, a circulating inlet 1.12, an aeration head 1.3 and a sludge discharge outlet 1.9. The top of the sequencing batch reactor 1 is provided with an overflow outlet 1.13 and a circulating outlet 1.11. The middle part of the sequencing batch reactor 1 is provided with multiple clean water discharge outlets that meet different volume exchange ratios, including clean water discharge outlet 1.6 and clean water discharge outlet 1.8.

[0058] Municipal sewage in the inlet tank 3 is introduced into the bottom of the sequencing batch reactor 1 through the sewage inlet 1.5 via the inlet peristaltic pump 1.4. Gas is introduced into the aeration head 1.3 at the bottom of the sequencing batch reactor 1 through the pipeline via the air pump 1.2. The aeration rate of the aeration head 1.3 is adjusted by the flow meter 1.1. Liquid at the top of the sequencing batch reactor 1 is introduced into the bottom of the sequencing batch reactor 1 through the circulation outlet 1.11 and circulation inlet 1.12 via the circulation pump 1.10. The treated liquid is introduced into the outlet tank 4 through the clean water outlet 1.8 via the outlet peristaltic pump 1.7. The inlet peristaltic pump 1.4, the air pump 1.2, the circulation pump 1.10 and the outlet peristaltic pump 1.7 are all connected to the PLC control system 2.

[0059] Example 2

[0060] A method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep nitrogen and phosphorus removal in low-concentration municipal wastewater includes the following steps:

[0061] Using municipal wastewater as the substrate, the chemical oxygen demand (COD) concentration was 200 mg / L, the total phosphorus concentration was 8 mg / L, and the ammonia nitrogen concentration was 40 mg / L. The characteristics of the influent water quality are shown in the table below:

[0062] Concentration (mg / L) 200 8 40 7.5

[0063] S1: System Startup Phase

[0064] The system startup phase adopts an anaerobic / aerobic operation mode, while the sequencing batch reactor operates intermittently. The cycle time can be changed according to actual needs. Specifically, it includes four steps: influent, circulation, aeration, and effluent. No anoxic step is included. For detailed operation, please refer to S11 to S14.

[0065] S11: Water intake stage

[0066] Start the inlet peristaltic pump 1.4 to introduce municipal sewage from inlet tank 3 into the bottom of sequencing batch reactor 1 through sewage inlet 1.5 to complete the inlet process;

[0067] S12: Cyclic Phase

[0068] After the water intake is completed, the anaerobic circulation stage begins. The circulation pump 1.10 is turned on to introduce the liquid at the top of the sequencing batch reactor 1 into the bottom of the sequencing batch reactor 1 through the circulation outlet 1.11 and the circulation inlet 1.12 to achieve internal circulation.

[0069] S13: Aeration Stage

[0070] Start the air pump 1.2 to introduce gas into the aeration head 1.3, and adjust the aeration rate of the aeration head 1.3 through the flow meter 1.1. The dissolved oxygen concentration at the end of the aeration stage is 6 mg / L.

[0071] S14: Drainage Stage

[0072] After settling for a period of time, start the peristaltic pump 1.7 to introduce the treated liquid into the outlet tank 4 through the clean water drain 1.8 to complete the drainage process;

[0073] The inlet peristaltic pump 1.4, air pump 1.2, circulation pump 1.10 and outlet peristaltic pump 1.7 are all connected to the PLC control system 2. The PLC control system 2 realizes the continuous cyclic operation of S11 to S14, that is, the process of water inlet-anaerobic circulation-aerobic aeration-drainage.

[0074] Fifteen days after the start-up of step S1, new particles are generated in the sequencing batch reactor. These new particles are small, light yellow granules, and the sludge age is 15 days. At this time, the effluent ratio is increased from 50% to 70%. After circulation, the system enters the stable period of step S1. The TN removal rate increases from 36% to 46%, and the TP removal rate increases from 37% to 75%. The abundance of PAOs increases from 4.56% to 10.46% (achieving rapid enrichment of PAOs), the abundance of GAOs increases from 5.39% to 5.61%, and NOB increases from 2.45% to 2.59%, basically achieving complete granulation of the sludge particles. 50 It is 0.8mm.

[0075] The time parameters for each stage in step S1 are shown in the table below:

[0076]

[0077] S2: Operation Phase

[0078] During the operation phase, an anaerobic / aerobic / anoxic (A / O / A) operating mode is adopted. For specific operation, please refer to S21 to S22:

[0079] S21: Anaerobic / aerobic follows the steps described in S12 and S13, with the addition of a post-anoxic section. That is, after aeration is completed, the circulation pump 1.10 is turned on to introduce the liquid at the top of the sequencing batch reactor 1 into the bottom of the sequencing batch reactor 1 through the circulation outlet 1.11 and the circulation inlet 1.12 to achieve anoxic internal circulation.

[0080] This stage involves rapid enrichment of DGAOs:

[0081] The aeration rate was adjusted to 0.3 L / min using an air pump and aeration heads, while the aeration time was gradually shortened. The dissolved oxygen concentration was controlled to 3 mg / L, the sludge age was extended to 35 days, and the sludge concentration was increased to 6.0 g / L.

[0082] During this phase, the system's TN removal rate increased from 46% to 73%, and the TP removal rate increased from 75% to 84%. PAO abundance decreased from 10.46% to 8.99%, DPAO abundance was approximately 3.40%, GAO abundance increased from 5.61% to 16.73%, DGAO abundance was approximately 5.12%, and NOB abundance decreased to 0.07%.

[0083] The time parameters for this period are shown in the table below:

[0084] Time (min) 3 90 90 90 5 3

[0085] S22: When the PO4 content of the water outlet is 1.8... 3- When the concentration remained close to 0.5 mg / L for three consecutive days, a "carbon source multiplication coupling PO4" method was employed. 3- "Concentration control technology" means that when the anaerobic reaction ends, the effluent peristaltic pump 1.7 is started to drain the water, and then water is refilled and the steps described in S21 are started, namely the anaerobic / aerobic / anoxic (A / O / A) operation mode.

[0086] This stage involves rapid enrichment of DPAOs:

[0087] Further adjust the aeration rate and aeration duration, extend the duration of the anoxic phase, and appropriately extend the duration of the subsequent anoxic phase (adjust between 1.0-2.5 hours), extending the sludge age to 40-50 days.

[0088] When the water contains PO4 3- When the concentration remained close to 0.5 mg / L for three consecutive days, a "periodic carbon source multiplication coupled with PO4" method was employed. 3- The "concentration control technology" means that at the end of the anaerobic reaction, 70% of the volume of high-concentration phosphate supernatant is manually discharged, followed by water inflow (when re-inflowing water, the COD concentration of the influent is increased from 200 mg / L to 400 mg / L in a single cycle), and internal circulation is started (lasting 1.5 hours). After the anaerobic stage, it is switched to aerobic aeration (1.5 h), and then enters the anoxic stage (1.5 h) for further nitrogen and phosphorus removal.

[0089] When the water discharged from the water purifier drain has PO4 3- When the concentration is below 0.3 mg / L, this operation should be stopped. This operation involves regulating the PO4 concentration in the anaerobic section system. 3- The concentration and secondary substrate addition strategy achieves synergistic optimization of carbon source secondary storage and utilization and denitrification and phosphorus removal functions, which helps to activate the activity of internal carbon source functional microorganisms, effectively inhibit the growth advantage of GAOs, and establish a dynamic balance between PAOs and GAOs.

[0090] The PLC control system continuously cycles through phases S21 to S22, with sludge age controlled to 30-40 days during this phase via sludge discharge. During this phase, the average particle size of the sludge particles stabilizes at 1.5 mm, and yellow-white particles appear in the system at a ratio of 3:2. The system achieves nearly 100% TN and TP removal rates. PAO abundance increases from 8.99% to 28.37% (DPAO abundance accounts for approximately 33.3%), and GAO abundance increases from 16.73% to 35.7% (DGAO abundance accounts for approximately 100%). NOB is not detected. The yellow particles are predominantly GAOs (including DGAOs), while the white particles are predominantly PAOs (including DPAOs), achieving targeted regulation and balance of PAOs / DPAOs and GAOs / DGAOs abundance. The time parameters during this phase are shown in the table below.

[0091] Time (min) 3 90 90 90 1 3

[0092] The entire wastewater treatment process in Example 2 includes anaerobic, aerobic, and anoxic stages. The microbial community activity differs in each stage, and the specific principles are as follows:

[0093] Anaerobic stage: Both polyphosphate-accumulating bacteria (PAOs) and polysaccharide-accumulating bacteria have internal carbon source storage functions, converting COD in the influent into internal carbon sources. Under anaerobic conditions, PAOs can obtain energy through polyphosphate (poly-P) hydrolysis and glycogenolysis (Glycolysis), while simultaneously absorbing organic carbon and converting it into poly-β-hydroxy fatty acid esters (PHA), and fully releasing phosphorus externally. During this stage, denitrifying bacteria can utilize exogenous organic matter to denitrify residual nitrite and nitrate nitrogen in the water.

[0094] Aerobic Stage: Nitrification is an autotrophic biological oxidation process driven sequentially by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). During this stage, ammonia nitrogen is oxidized to nitrite and nitrate nitrogen. This invention, due to its lower dissolved oxygen levels, allows for control of short-cut nitrification. Because of the unique structure of granular sludge, most aerobic microorganisms reside on the surface. PAOs possess the unique ability to absorb excess orthophosphate under aerobic conditions, while simultaneously degrading stored PHA and utilizing oxygen as an electron acceptor. At this time, DGAOs consume internal carbon sources to complete short-cut endogenous denitrification, while DPAOs consume internal carbon sources to absorb nitrogen and phosphorus, completing short-cut endogenous denitrification for phosphorus removal. Simultaneous short-cut nitrification and endogenous denitrification for phosphorus removal mainly occur during this stage.

[0095] Anoxic stage: PAOs continue to absorb phosphate using the residual dissolved oxygen in the system. Since the COD removal rate at the end of the anaerobic stage is close to 100%, nitrogen and phosphorus removal at this stage mainly relies on DPAOs and DGAOs. The nitrite, nitrate and phosphate remaining at the end of the aerobic stage are utilized by DPAOs at this stage, and some nitrite and nitrate are utilized by DGAOs.

[0096] The technical principle is as follows:

[0097] 1) Principle of inhibiting filamentous bacteria accumulation of PAOs: In the anaerobic stage, controlling the speed of the circulating pump ensures sufficient contact between sludge and nutrients, which is beneficial for improving the absorption and utilization of nutrients by microorganisms. Appropriately extending the anaerobic period further promotes carbon source consumption. In the aerobic stage, the dissolved oxygen concentration is controlled above 6 mg / L, and gradually shortening the settling time allows for the discharge of flocculent granular sludge, which also helps inhibit the growth and reproduction of filamentous bacteria. Since PAOs are short-generation-cycle microorganisms, their maximum generation cycle is even shorter than that of nitrifying bacteria. This means that PAOs can undergo more growth and reproduction cycles within the same time frame, resulting in a relatively short sludge lifetime (SRT). Regular sludge discharge is beneficial for PAO accumulation, while gradually increasing the volumetric exchange ratio and volumetric loading can accelerate sludge growth.

[0098] 2) Principle of NOB inhibition: During the aerobic stage, ammonia nitrogen is oxidized to nitrite nitrogen and then to nitrate nitrogen by nitrifying bacteria. By gradually reducing the aeration rate and aeration time, the lower dissolved oxygen in the aerobic stage inhibits the activity of NOB, thus preventing nitrite nitrogen from being further converted into nitrate nitrogen. At the same time, low dissolved oxygen is conducive to the growth and reproduction of DPAOs and DGAOs.

[0099] 3) Principle of balancing GAOs and PAOs: using "periodic carbon source multiplication coupling PO4" 3- Concentration control technology effectively balances the competition between PAOs and GAOs. This method enhances the metabolic drive of PAOs by regulating phosphate ion concentration, thereby weakening the competition from GAOs. Furthermore, under anaerobic conditions, PAOs and GAOs compete for carbon sources. In actual municipal wastewater treatment processes with relatively low carbon source constraints, GAOs often have a greater advantage in carbon source competition than PAOs. Cyclic doubling of organic carbon sources can provide competitive conditions for PAO growth and metabolism, ensuring an abundance balance between PAOs and GAOs and achieving "carbon regulation and phosphorus control, and simultaneous removal of nitrogen and phosphorus." Simultaneously, a longer sludge age is more conducive to the enrichment of slow-growing microorganisms. Since the sludge age of PAOs is shorter than that of DPAOs and that of GAOs is shorter than that of DGAOs, appropriately extending the sludge age helps to enrich DPAOs and DGAOs.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for targeted regulation of polyphosphorus bacteria and glycan bacteria for deep denitrification and dephosphorization of low-concentration municipal sewage, characterized in that: The method for deep nitrogen and phosphorus removal from wastewater is carried out through a sequencing batch reactor (SBR), which includes a SBR reactor and a PLC control system. The bottom of the sequencing batch reactor is equipped with a wastewater inlet, a circulating inlet, an aeration head, and a sludge discharge outlet. The top of the sequencing batch reactor is equipped with an overflow outlet and a circulating outlet. The middle of the sequencing batch reactor is equipped with a clean water discharge outlet that meets different volume exchange ratios. The municipal sewage in the inlet tank is introduced into the bottom of the sequencing batch reactor through the sewage inlet by the inlet peristaltic pump. The air pump introduces gas into the aeration head at the bottom of the sequencing batch reactor through the pipeline for aeration. The liquid at the top of the sequencing batch reactor is introduced into the bottom of the sequencing batch reactor through the circulation inlet by the circulation pump. The treated liquid is introduced into the outlet tank through the clean water outlet by the outlet peristaltic pump. The inlet peristaltic pump, air pump, circulation pump, and outlet peristaltic pump are all connected to the PLC control system; The method for targeted regulation of polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria for deep nitrogen and phosphorus removal in low-concentration municipal wastewater is as follows: S1: System Startup Phase The system startup phase adopts an anaerobic / aerobic operation mode, while the sequencing batch reactor operates intermittently, specifically including four steps: influent, circulation, aeration, and effluent. See S11~S14 for detailed operation instructions. S11: Water intake stage Start the inlet peristaltic pump to introduce municipal sewage from the inlet tank into the bottom of the sequencing batch reactor through the sewage inlet, thus completing the inlet process; S12: Cyclic Phase After the water intake is completed, the anaerobic circulation stage begins. The circulation pump is turned on to introduce the liquid at the top of the sequencing batch reactor into the bottom of the sequencing batch reactor through the circulation inlet to achieve internal circulation. S13: Aeration Stage Start the air pump to introduce gas into the aeration head, and adjust the aeration rate of the aeration head through the flow meter. The dissolved oxygen concentration at the end of the aeration stage should not be lower than 6 mg / L. S14: Drainage Stage Start the peristaltic pump to introduce the treated liquid into the outlet tank through the clean water drain to complete the drainage process; The PLC control system enables continuous cyclic operation of S11~S14. After 15 days of startup, new particles are generated in the sequencing batch reactor. The new particles are light yellow and the sludge age is 10~20 days. At this time, the drainage ratio is increased from 50% to 70%. S2: Operation Phase During the operation phase, an anaerobic / aerobic / anoxic operating mode is adopted. For specific operation, please refer to S21~S22: S21: The anaerobic and aerobic stages adopt steps S12 and S13, and a post-anoxic stage is added. That is, after aeration is completed, the circulation pump is turned on to introduce the liquid at the top of the sequencing batch reactor into the bottom of the sequencing batch reactor through the circulation inlet to achieve anoxic internal circulation. S22: When the effluent PO4 3- concentration is close to 0.5 mg / L for three consecutive days, the anaerobic reaction is ended, the effluent peristaltic pump is started to discharge the supernatant, and then the water is recharged and step S21 is started; when the water is recharged, the COD concentration is increased from 200 mg / L to 400 mg / L in a single cycle, and when the anaerobic PO4 3- concentration is less than 20 mg / L, the effluent PO4 3- concentration of the clean water drain is less than 0.3 mg / L, the operation is stopped; In the aerobic stage, the aeration rate is controlled by a flow meter, and the dissolved oxygen concentration at the end of the aeration stage is not higher than 2.0 mg / L; The PLC control system enables continuous cyclic operation of S21~S22, and the sludge age is controlled to be 30~40 days during the operation phase by sludge discharge.

2. The method according to claim 1, characterized in that: Municipal activated sludge was used as inoculum sludge, and the chemical oxygen demand (COD) concentration in municipal wastewater was 100-200 mg / L, the ammonia nitrogen concentration was 30-60 mg / L, and the total phosphorus concentration was 3-8 mg / L.

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