A periodic optimization aerobic granular sludge sewage treatment method

Abstract

This invention provides a cycle-optimized aerobic granular sludge wastewater treatment method, relating to the field of wastewater treatment. This invention employs a column-type SBR with a high aspect ratio of 8-12:1, adapting the A / O / A or A / O cycle to the influent TN concentration. Under a 6-hour total cycle, phase time is quantitatively allocated (aerobic phase proportion ≥55%). Combined with three-stage gradient control of settling time and the synergistic effect of hydraulic upflow velocity, along with standardized control of influent water quality, this achieves rapid AGS formation and long-term stability. This invention improves the AGS formation rate and shortens the start-up cycle. By adapting the cycle type to the influent water quality, it addresses the process requirements of shear stress, nitrogen removal, and phosphorus removal, solving the problem of unbalanced pollutant removal efficiency in existing technologies. This invention requires no chemical reagents and can directly modify existing SBR reactors, resulting in low modification costs.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment and resource utilization technology, specifically to a periodically optimized aerobic granular sludge wastewater treatment method. Background Technology

[0002] Aerobic granular sludge (AGS) technology, as a core upgrade and alternative to the traditional activated sludge process, has become the mainstream technology in municipal and industrial wastewater treatment due to its core advantages: simultaneous decarbonization, nitrogen and phosphorus removal, excellent sludge settling performance, reduced reactor footprint compared to traditional processes, lower operating energy consumption, and lower residual sludge production. Currently, the industrial application of this technology mainly relies on sequencing batch reactors (SBRs). However, existing AGS-SBR wastewater treatment processes have the following problems in actual industrial operation: 1. Lack of Quantitative Standards and Water Quality Adaptability in Cycle Phase Time Allocation: In existing research and engineering applications, there is no unified quantitative standard for setting the aerobic phase time for the 6-hour conventional single operating cycle of the AGS-SBR process. The fluctuation range is 60-240 minutes, accounting for 17%-67% of the total single operating cycle time. Furthermore, differentiated phase time allocation schemes have not been designed for different influent water qualities such as medium-to-high nitrogen municipal wastewater and low-nitrogen industrial wastewater, resulting in significant fluctuations in system treatment performance. For medium-to-high nitrogen wastewater, blindly shortening the aerobic phase can lead to insufficient particle shear stress, while extending the aerobic phase can compress denitrification time. For low-nitrogen wastewater, setting an independent anoxic phase can result in wasted carbon source and energy consumption, and can also damage particle stability.

[0003] 2. The limited particle screening and control methods result in slow formation speed and poor stability: Existing processes only achieve sludge screening through a simple fixed settling time, without combining it with coordinated control of the hydraulic upflow velocity. Furthermore, the settling time lacks gradient optimization design, failing to exert a step-by-step selection pressure on the sludge. Excessive settling time leads to the retention of flocculent sludge, which competes with AGS for carbon sources and living space. Insufficient settling time results in the loss of unformed microparticles. Ultimately, the initial formation time of AGS generally exceeds 20 days, and the maturation period requires more than 3 months. Moreover, the particle size distribution after formation is uneven, with particles >0.2mm in diameter accounting for only 70%-75%, further exacerbating the instability of system operation. Summary of the Invention

[0004] This invention provides a periodically optimized aerobic granular sludge wastewater treatment method to solve at least one of the technical problems mentioned in the background art.

[0005] To address the aforementioned technical problems, this invention discloses a periodically optimized aerobic granular sludge wastewater treatment method, comprising: Step 1: Anaerobic influent stage: Pump the wastewater to be treated into the column-type sequencing batch reactor to complete the anaerobic influent stage; Step 2: Anaerobic reaction stage: After the water intake is completed, the anaerobic reaction stage begins. During the anaerobic reaction stage, mechanical stirring at 18-22 rpm (which can be finely adjusted on-site by the frequency converter) is used to maintain DO < 0.5 mg / L. Step 3: Aerobic reaction stage: After the anaerobic stage ends, switch to aerobic aeration mode: Turn on the microporous aerator at the bottom of the column-type sequencing batch reactor and control the apparent aeration rise rate to 1-1.5 cm / s. Precisely adjust the aeration volume using an aeration flow meter to maintain the DO concentration in the column-type sequencing batch reactor at 2-4 mg / L. Provide sufficient shear stress for AGS to promote the directional secretion of extracellular polymeric substances (EPS). Step 4: When dealing with medium-to-high nitrogen wastewater, execute the anoxic reaction stage: After the aerobic stage, stop aeration and switch to the anoxic stirring mode: use mechanical stirring at 18-22 rpm (which can be finely adjusted on site by the frequency converter) to maintain DO < 0.5 mg / L, and use the nitrates remaining in the aerobic stage for denitrification. Step 5: Settling and Screening Stage After the reaction stage is completed, aeration and stirring are stopped, and the sludge-water separation stage begins. The drainage control parameters for the current operating cycle are determined based on the growth stage of the granular sludge. Step 6: Drainage stage: After settling, drain the water and control the volume exchange ratio to 50%; after drainage, enter the next operating cycle.

[0006] Preferably, the drainage control parameters include the hydraulic upflow velocity; Start-up phase: Drainage begins 20 minutes after the sedimentation phase starts, with a hydraulic upflow velocity >1.5 m / h during the drainage phase; Granulation period: Drainage is carried out 10 minutes after the start of the sedimentation stage, and the hydraulic upflow velocity during the drainage stage is >3m / h; Maturation stage: Drainage begins 5 minutes after the start of the sedimentation stage, with a hydraulic upflow velocity of >6m / h during the drainage stage.

[0007] Preferably, the column-type sequencing batch reactor has a height-to-diameter ratio of 8-12:1. The height-to-diameter ratio is a core structural parameter that affects the uniform distribution of aeration shear stress and the hydraulic screening effect, and the reactor volume can be flexibly adjusted according to the actual treatment scale. Preferably, the reactor temperature is controlled at 28±2℃ throughout each operating cycle.

[0008] Preferably, the total runtime of the operation cycle is 6 hours. For medium- to high-nitrogen wastewater, an A / O / A (anaerobic / aerobic / anoxic) cycle is adopted, with the aerobic reaction time accounting for greater than or equal to 55% of the total time of a single operating cycle, and the anoxic reaction time accounting for 5%-10% of the total time of a single operating cycle. The aerobic phase accounts for no less than 55% of the total time, providing continuous and sufficient shear stress for the AGS. The anoxic phase time is dynamically adjusted according to the influent TN concentration (10% when TN>50mg / L, and 5%-10% when 30mg / L≤TN≤50mg / L), achieving dual optimization of denitrification efficiency and particle stability. For low-nitrogen wastewater, an A / O (anaerobic / aerobic) cycle is adopted, with the aerobic reaction time accounting for more than 65% of the total time of a single operating cycle; the proportion of the aerobic phase is increased to 65%, further strengthening the AGS shear stress and avoiding particle loosening and waste of carbon source and energy caused by ineffective anoxic stages.

[0009] Preferably, the influent water quality is controlled as follows: COD concentration 500-600 mg / L, NH4+ concentration 500-600 mg / L. + -N concentration 40-60 mg / L, PO4 3- The influent concentration is 8-12 mg / L, pH is 7.5±0.2, and 1 mL of a trace element solution containing Fe, Mn, and Zn is added per liter of influent. For the water quality characteristics of medium-concentration municipal and industrial wastewater, standardized control of influent water quality parameters ensures that the biodegradability of the wastewater matches the metabolic needs of the AGS microbial community, eliminating the need for additional flocculants, regulators, or other chemical agents. The carbon-nitrogen-phosphorus ratio is adapted to the simultaneous decarbonation, nitrogen removal, and phosphorus removal metabolism of the AGS microbial community; the influent pH is adjusted to 7.5±0.2 by adding sodium bicarbonate to provide a suitable acid-base environment for microbial metabolism; 1 mL of a solution containing essential trace elements such as Fe, Mn, and Zn is added per liter of influent to supplement the nutrients required for microbial growth and metabolism, enhancing microbial activity and EPS secretion capacity.

[0010] Preferably, the start-up period is 1-16 days after the column-type sequencing batch reactor is inoculated with sludge; the granulation period is 17-31 days after the column-type sequencing batch reactor is inoculated with sludge; and the maturity period is 32-94 days after the column-type sequencing batch reactor is inoculated with sludge.

[0011] Preferably, in the A / O / A cycle, the duration of the anoxic reaction phase is dynamically adjusted according to the influent TN concentration: when the influent TN concentration > 50 mg / L, the duration of the anoxic reaction phase is 10% of the total duration of a single operating cycle; when the influent TN concentration is 30-50 mg / L, the duration of the anoxic reaction phase is 5%-10% of the total duration of a single operating cycle; when the influent TN concentration < 30 mg / L, the cycle is switched to A / O.

[0012] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The formation speed of AGS is improved and the start-up cycle is shortened: By using a stepwise selection of pressure based on settling time and hydraulic upflow velocity, combined with sufficient shear stress in the aerobic phase, the time for the first appearance of AGS is shortened to 12 days and the maturity period is only 32 days. This is significantly shorter than the existing A / O / A process (the conventional maturity period is more than 3 months), which greatly reduces the start-up time and energy consumption cost of the process.

[0014] 2. AGS exhibits good long-term stability, reducing the risk of disintegration: Through quantitative control of the aerobic phase ratio (not less than 55% / 65%), the EPS yield of AGS can reach 903.8-1273.1 mg / L, and the protein / polysaccharide (PN / PS) ratio is maintained within the optimal range of 1.1-1.2. The system operated continuously for 94 days without significant particle breakage or disintegration, and the sludge volume index (SVI) remained low. 30 The average value was consistently below 40 mL / g.

[0015] 3. By adapting the cycle type to the influent water quality, the process requirements of shear stress, denitrification, and phosphorus removal are taken into account, thus solving the problem of unbalanced pollutant removal efficiency in existing technologies; When treating high-nitrogen municipal wastewater using an A / O / A cycle, the influent COD concentration is 500-600 mg / L (average 546±46 mg / L), and NH4+ concentration is... + -N concentration 40-60 mg / L (average 55±4 mg / L), PO4 3- -P concentration 8-12 mg / L (average 9±1 mg / L), TN concentration 55±5 mg / L, resulting in effluent COD concentration 49±33 mg / L and NH4+ concentration. + -N concentration 7±3 mg / L, TN concentration 8±4 mg / L, PO4 3- -P concentration 3±2 mg / L; When treating low-nitrogen industrial wastewater using an A / O cycle, the influent COD concentration is 500-600 mg / L (average 581±19 mg / L), and NH4+ concentration is... + -N concentration 18-22 mg / L (average 20±2 mg / L), PO4 3- -P concentration 8-12 mg / L (average 10±2 mg / L), TN concentration 22±2 mg / L, resulting in effluent COD concentration 42±27 mg / L, NH4+ + -N concentration 4±1 mg / L, TN concentration 12±6 mg / L, PO4 3- -P concentration 3±1 mg / L.

[0016] 4. On-site staff only need to switch the cycle type and fine-tune the anoxic phase time according to the influent TN concentration to achieve stable operation; no additional chemical agents are required, reducing agent costs and secondary pollution; the core structural parameters of the reactor (height-to-diameter ratio 8-12:1) can be adapted to different treatment scales and can be directly applied to the upgrade and transformation of existing SBR reactors without the need for new systems. The transformation cost is lower than that of new systems and it is suitable for the deep treatment of medium-concentration municipal and low-nitrogen industrial wastewater.

[0017] 5. Through extensive orthogonal experiments and engineering verification, this invention systematically studies the coupling mechanism between cycle type and phase time allocation, clarifies the quantitative correlation between the aerobic phase ratio and AGS stability, and proposes an optimized operation method for AGS-SBR process that takes into account AGS formation efficiency, long-term stability, and simultaneous pollutant removal performance. This effectively solves the core problem of the difficulty in balancing "particle stability - pollutant removal rate" in existing technologies, while shortening the AGS formation cycle and reducing the retrofit cost of existing SBR systems.

[0018] The design, with an aerobic reaction phase ratio of no less than 55%, enables the extracellular polymeric substance (EPS) production of aerobic granular sludge in the reactor to be ≥900 mg / L, and the protein / polysaccharide (PN / PS) ratio to be stable at 1.1-1.2. Combined with the shearing effect generated by stirring and the upward flow velocity of the hydraulic system, it can improve the stability of granular operation, which is conducive to inhibiting granular loosening and excessive proliferation of filamentous bacteria, and alleviating the problem of granular disintegration during long-term operation.

[0019] The three-stage synergistic gradient control of settling time and hydraulic upflow velocity adopts a synergistic control method of decreasing the settling time gradient and increasing the hydraulic upflow velocity gradient. This creates a stepped selection pressure on the sludge in three stages, gradually eliminating flocculent sludge, promoting AGS aggregation, and screening for AGS with stable and uniform particle size. The parameters at each stage are precisely matched with the control objectives, as detailed below: (1) Start-up period (days 1-16): Settling time 20 min, hydraulic upflow velocity > 1.5 m / h. The core objective is to eliminate flocculent sludge with poor settling performance, retain sludge bacteria with flocculation potential, and lay the foundation for AGS formation. (2) Granulation period (days 17-31): The settling time is reduced to 10 min and the hydraulic upflow velocity is >3 m / h. The core objective is to enhance the aggregation of sludge particles, promote the formation of initial AGS (particle size 0.2-0.5 mm), and further discharge unaggregated loose sludge. (3) Maturity period (days 32-94): Settling time is reduced to 5 min, hydraulic upflow velocity is >6 m / h. The core objective is to screen stable AGS with uniform particle size, so that the proportion of AGS with diameter >0.2 mm in the reactor is ≥90%, while maintaining the dense structure of AGS to avoid the growth of filamentous bacteria. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the process of the present invention; Figure 2 The AGS formed by the A / O / A cycle of this invention; Figure 3 This is an AGS formed from the existing conventional A / O / A cycle. Detailed Implementation

[0021] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions and features of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] The present invention provides the following embodiments: This invention constructs an integrated AGS wastewater treatment process system based on a column-type sequencing batch reactor (SBR). Through the coupling of technologies such as differentiated selection of cycle type, precise quantitative allocation of phase time, three-stage gradient control of settling time, and synergistic optimization of influent water quality, combined with standardized control of reactor operating parameters, it achieves rapid formation, long-term stability, and simultaneous and efficient removal of pollutants in AGS.

[0024] This invention provides a periodically optimized aerobic granular sludge wastewater treatment method, such as... Figure 1 As shown, it includes: Example 1: A / O / A cycle treatment of medium-concentration municipal wastewater: I. Experimental Materials and Equipment 1. Reactor configuration: A column-type SBR reactor with a height-to-diameter ratio of 10:1 (inner diameter 10cm, height 100cm, working volume 7.6L) is used; bottom installation... 5mm microporous aerator, connected to an air compressor with an accuracy of ±0.01mm. 3 An aeration flow meter with a flow rate of / h controls the apparent aeration rise rate of 1.2cm / s within the reactor; a magnetic stirrer is installed on the side wall with an adjustable stirring rate of 18-22rpm; a water bath thermostat is provided with a temperature control accuracy of ±0.5℃; and a drainage rate control module is set up to precisely control the hydraulic rise velocity and volume exchange ratio.

[0025] 2. Inoculation sludge: Activated sludge from the aerobic tank of a municipal wastewater treatment plant. After inoculation, the mixed liquor suspended solids concentration (MLSS) in the reactor was 3000±200 mg / L, and the sludge volume index (SVI) was [value missing]. 30 =120±10mL / g.

[0026] 3. Influent Water Quality: This embodiment uses actual high-nitrogen municipal wastewater for verification, and uses artificially synthesized water meeting the same water quality indicators as the design benchmark, maintaining consistent water quality parameters between the two. The water quality parameters meet the influent control requirements of this invention: COD concentration 500-600 mg / L (average 546±46 mg / L), NH4+... + -N concentration 40-60 mg / L (average 55±4 mg / L), PO4 3- -P concentration 8-12 mg / L (average 9±1 mg / L), TN concentration 55±5 mg / L; the influent pH is adjusted to 7.5±0.2 with sodium bicarbonate, and 1 mL of trace element solution containing Fe, Mn, Zn and Cu is added per liter of influent to ensure the biodegradability of wastewater.

[0027] II. Experimental Methods: 1. Basic operating parameters of the reactor: temperature is controlled at 28±2℃, volume exchange ratio is 50%; DO concentration is controlled at 2-4mg / L in the aerobic stage, and the stirring rate is 20rpm and DO concentration is <0.5mg / L in the anaerobic / anoxic stage.

[0028] 2. Cycle type and phase time (stage duration) allocation: The A / O / A cycle is adopted, with a total cycle of 6 hours (360 minutes). The phase times are as follows: anaerobic influent (0-35 minutes), anaerobic reaction (35-121 minutes), aerobic reaction 55% (121-319 minutes), anoxic reaction (319-355 minutes), sedimentation and drainage 5 minutes; the idle period of 9 minutes (not included in the above 6 hours) is distributed between each stage to ensure the stability of the system sequence.

[0029] 3. Coordinated regulation of settling time and hydraulic upflow velocity: The regulation is carried out in three stages: during the start-up period (days 1-16), the settling time is 20 min and the hydraulic upflow velocity is 1.6 m / h; during the granulation period (days 17-31), the settling time is 10 min and the hydraulic upflow velocity is 3.2 m / h; during the maturity period (days 32-94), the settling time is 5 min and the hydraulic upflow velocity is 6.1 m / h.

[0030] 4. Monitoring Indicators and Methods: Daily monitoring of influent and effluent COD and NH4. + -N, TN, PO4 3- -P concentration was determined using national standard methods; AGS particle size distribution (laser particle size analyzer) and SVI were measured in the reactor every 3 days. 30 Extracellular polymeric substances (EPS) production and PN / PS ratio were monitored continuously for 94 days, recording the AGS formation time and whether there was particle breakage or disintegration.

[0031] III. Experimental Results and Analysis 1. AGS formation efficiency: Initial aerobic granular sludge with a particle size ≥0.2mm first appeared on day 12, and entered the maturity stage on day 32. Compared with the conventional A / O / A comparative process (initial formation time ≥20 days, maturity stage ≥90 days), the formation time and maturity stage are shortened, verifying that the present invention can achieve rapid AGS formation.

[0032] 2. AGS Particle Performance: During the mature stage, the average particle size of AGS is 1.3±0.3mm, with 92% of particles having a diameter >0.2mm; SVI 30 The stable concentration was 37.3±9.2 mL / g, and no particle breakage or disintegration was observed after 94 days of continuous operation. The EPS yield was 1273.1±225.3 mg / L, and the PN / PS ratio remained stable at 1.2. Compared with the existing process, the EPS yield was increased by more than 30%, proving that the present invention can significantly improve the stability of AGS particles through the quantitative proportion of aerobic phase and the synergistic regulation of sedimentation and hydraulics.

[0033] 3. Pollutant removal efficiency: During the mature stage, the effluent water quality indicators were: COD concentration 49±33 mg / L; NH4+ concentration 49±33 mg / L. + -N concentration 7±3 mg / L; TN concentration 8±4 mg / L; PO4 3- -P concentration 3±2 mg / L.

[0034] Example 2: A / O cycle treatment of low-nitrogen industrial wastewater: I. Experimental Materials and Equipment 1. Reactor configuration: Completely consistent with Example 1, except that the independent control module for the stirrer in the anoxic stage is removed, and only the stirring rate control in the anaerobic / aerobic stage is retained to ensure the compatibility of the equipment and the process.

[0035] 2. Inoculation sludge: Same as in Example 1, MLSS = 3000 ± 200 mg / L, SVI 30 =120±10mL / g.

[0036] 3. Influent water quality: Actual low-nitrogen industrial wastewater is used, meeting the influent control requirements of this invention: COD concentration 500-600 mg / L (average 581±19 mg / L), NH4+... + -N concentration 18-22 mg / L (average 20±2 mg / L), PO4 3- -P concentration 8-12 mg / L (average 10±2 mg / L), TN concentration 22±2 mg / L; influent pH adjusted to 7.5±0.2, no additional trace element solution is needed (the wastewater contains sufficient Fe, Mn and other elements).

[0037] II. Experimental Methods: 1. Basic operating parameters of the reactor: consistent with Example 1, temperature 28±2℃, volume exchange ratio 50%; DO=2-4mg / L in the aerobic stage, stirring rate 20rpm in the anaerobic stage, DO<0.5mg / L.

[0038] 2. Cycle type and phase time allocation: The A / O cycle is adopted, with a total cycle of 6 hours (360 minutes). The phase time can be: anaerobic influent 0-36 minutes, anaerobic reaction 36-115 minutes, aerobic reaction 115-350 minutes, sedimentation 5 minutes, and drainage 5 minutes; there is no independent anoxic stage to avoid carbon source and energy waste.

[0039] 3. Coordinated regulation of settling time and hydraulic upflow velocity: Completely consistent with Example 1, with no adjustment to the three-stage parameters, verifying the universality of the regulation scheme of this invention.

[0040] 4. Monitoring indicators and methods: Same as in Example 1, continuous monitoring for 94 days.

[0041] III. Experimental Results and Analysis 1. AGS formation efficiency: Initial AGS with a particle size ≥0.2mm first appeared on day 11, and entered the maturity stage on day 30. The forming speed was better than that of Example 1. This is because after the ineffective hypoxia stage was eliminated, the aerobic shear stress continued to act, further promoting particle agglomeration.

[0042] 2. AGS Particle Performance: During the mature stage, the average particle size of AGS is 1.3±0.1mm, with 93% of particles having a diameter >0.2mm; SVI 30 =39.4±14.5mL / g, continuous operation for 94 days without disintegration; EPS production 903.8±274.1mg / L, PN / PS ratio 1.1, meeting the core indicator requirements for stable operation of AGS.

[0043] 3. Pollutant removal efficiency: During the mature stage, the effluent water quality indicators were: COD concentration 42±27 mg / L; NH4+ concentration 42±27 mg / L. + -N concentration 4±1 mg / L; TN concentration 12±6 mg / L; PO4 3- -P concentration 3±1 mg / L.

[0044] Comparative Example: Treatment of High-Nitrogen Municipal Wastewater by Existing Conventional A / O / A Processes To highlight the technical advantages of this invention, a control group based on the conventional A / O / A process was set up, using the same reactor, influent water quality, and inoculated sludge as in Example 1, only changing the cycle phase time distribution and sedimentation control method (conventional parameters in the prior art): 1. Existing technical parameters: The total A / O / A cycle is 6 hours (360 minutes), with anaerobic influent for 35 minutes, anaerobic reaction for 95 minutes, aerobic phase time for 120 minutes (accounting for 33% of the total cycle), and anoxic phase time for 60 minutes; the settling time is fixed at 20 minutes, the hydraulic upflow velocity is 1.2 m / h, there is no gradient control, and the remaining 30 minutes consists of the switching intervals between each stage; 2. Comparison Results: (1) AGS formation: The initial formation time is 25 days and the maturity period is 95 days, which is much longer than that of this invention; (2) Particle properties: Mature SVI 30 =85±10mL / g, after 60 days of operation, the particle breakage rate reached 16%, EPS yield was 750±100mg / L, and PN / PS=0.8; (3) Pollutant removal: TN removal rate 82%±3%, PO4 removal rate 82%±3%. 3- -P removal rate 45% ± 5%, PO4 3- -P removal rate is lower than that of this invention, and loose particles lead to poor system stability.

[0045] Table 1. Particle size distribution of aerobic granular sludge under different process cycles

[0046] Figure 2 The AGS formed by the A / O / A cycle in Example 1 (diameter 1.3±0.3mm, light yellow, spherical structure). Figure 3 AGS formed by conventional A / O / A process (diameter 0.9±0.4mm, brownish-brown, irregular surface, with attached filamentous bacteria).

[0047] Notes: During the anaerobic / anoxic phase, DO < 0.5 mg / L and stirring speed is 20 rpm; during the aerobic phase, DO = 2-4 mg / L and stirring is stopped; an idle period of 9 min is also set, which is not included in the total cycle of 6 h (360 min).

[0048] Overall verification conclusion of the example: The above embodiments and a comparative example verify that the aerobic granular sludge wastewater treatment method of the present invention, through the coupling technology of adapting to influent water quality, quantitative allocation of phase time, and coordinated gradient control of settling time and hydraulic upflow velocity, can achieve the following technical effects: 1. Rapid prototyping: AGS initial formation time ≤ 12 days, maturity period ≤ 32 days, significantly shortened compared to existing technologies; 2. Long-term stability: Continuous operation for 94 days without disintegration, EPS output and PN / PS ratio maintained at 1.1-1.2; 3. High efficiency removal: It can achieve simultaneous and efficient removal of carbon, nitrogen and phosphorus for both medium and high nitrogen municipal wastewater and low nitrogen industrial wastewater, solving the core bottleneck of existing technologies of "imbalance between particle stability and pollutant removal rate".

[0049] Optimized Implementation: The column-type sequencing batch reactor is divided into an upper effluent zone, a middle aeration and mixing zone, and a lower sludge enrichment zone from top to bottom. Turbidity detection device one is installed in the upper effluent zone (e.g., 100mm below the effective liquid level of the reactor), turbidity detection device two is installed at the boundary between the middle aeration and mixing zone and the lower sludge enrichment zone (specifically, the probe installation height needs to be 100-300mm higher than the upper interface of the lower sludge enrichment zone, and located above the air outlet of the aeration head, which is installed at the bottom of the reactor), and turbidity detection device three is installed in the lower sludge enrichment zone; an online DO meter is installed in the middle aeration and mixing zone.

[0050] The aerobic reaction phase also involves a synergistic regulation process, which includes: Step 401: Within the preset time period of the aerobic mixing section, control the operation of turbidity detection device 1, turbidity detection device 2, and turbidity detection device 3 multiple times. Step 402: Determine the key reference parameters based on the detection results of step 401. The key reference parameters include reference turbidity one, reference turbidity two, and reference turbidity three. An alarm will be triggered if any key reference parameter does not meet the allowable range of the corresponding reference parameter. Step 403: If no alarm is triggered in step 402, control the operation of turbidity detection device 1, turbidity detection device 2, turbidity detection device 3 and online DO meter multiple times within the preset time period 2 of the aerobic reaction section; Step 404: Determine the key analytical parameters based on the detection results of Step 403. The key analytical parameters include: the relative turbidity difference between the lower and middle layers, the turbidity deviation value of the upper layer, and the DO fluctuation coefficient. An alert is issued when any of the key analysis parameters meets the alert status (the key analysis parameter meets the alert range of the corresponding key analysis parameter).

[0051] Step 405: When at least one of the following conditions is met: relative turbidity difference between the lower and middle layers, turbidity deviation value of the upper layer, and DO fluctuation coefficient, the corrected apparent aeration rise rate and corrected aeration gap duty cycle are obtained based on the relative turbidity difference between the lower and middle layers, turbidity deviation value of the upper layer, DO fluctuation coefficient, and average DO value. Step 406: Update the apparent aeration rise rate to the corrected apparent aeration rise rate, update the aeration gap duty cycle to the corrected aeration gap duty cycle, and continue to complete the aerobic reaction stage.

[0052] The specific amendment rules are as follows: When only the relative turbidity difference between the lower and middle layers meets the warning condition: If the relative turbidity difference between the lower and middle layers falls into the warning range of excessive aeration, under normal operating conditions (0, 0.15], low conditions (0, 0.1]: the corrected apparent aeration rate of increase = the current apparent aeration rate of increase × 0.9, and the corrected aeration gap duty cycle = the current aeration gap duty cycle × 1.05. If the relative turbidity difference between the lower and middle layers falls into the insufficient aeration warning range, under normal operating conditions (0.25, 0.4) and low sludge concentration conditions (0.2, 0.3) (insufficient aeration, insufficient sludge bed disturbance): the corrected apparent aeration rise rate = current apparent aeration rise rate × 1.07, and the corrected aeration gap duty cycle = current aeration gap duty cycle × 0.95. When only the upper layer turbidity deviation value meets the warning condition: When the upper layer turbidity deviation reaches 0.15 times the reference turbidity: the corrected aeration gap duty cycle = the current aeration gap duty cycle × 0.9; when the condition of "turbidity rise within 5 minutes reaches 8% of the reference turbidity" is met, the corrected apparent aeration rise rate = the current apparent aeration rise rate × 0.92. DO fluctuation coefficient warning only: When the DO fluctuation coefficient reaches the warning limit (0.08 for medium and high nitrogen wastewater and 0.12 for low nitrogen wastewater), the corrected aeration gap duty cycle = current aeration gap duty cycle × 1.12; To avoid parameter conflicts, corrections should be performed in the following order of priority: First priority: execute the correction rule corresponding to the upper turbidity deviation value; Second priority: based on the first correction result, execute the correction rule corresponding to the DO fluctuation coefficient; Third priority: based on the second correction result, execute the correction rule corresponding to the lower and middle layer relative turbidity difference; In all correction steps, the single adjustment range shall not exceed ±15% of the current value.

[0053] Aeration gap duty cycle = Aeration time ÷ (Aeration time + Rest time); (1) The upper effluent zone is a clear water area with no or little sludge after aeration; the middle aeration mixing zone is the area where gas, liquid and solid three phases come into contact and the reaction is most intense; the lower sludge enrichment zone is the area at the bottom of the reactor where granular sludge is enriched, and it is the main site of denitrification reaction.

[0054] (2) The aerobic reaction stage is divided into three consecutive sub-segments: Aerobic mixing stage (initial aeration): This is the initial stage after aeration starts. The core purpose is to break the static state of the granular sludge bed and allow the sludge and water to mix thoroughly and evenly. At this time, the aeration intensity is high, the water body is in a state of strong turbulence, the granular sludge is disturbed and suspended and diffused by aeration, and a uniform flow field and concentration field are established throughout the reactor.

[0055] "Preset Time Period One" means collecting data during this period and taking the average turbidity value as the benchmark value for subsequent regulation.

[0056] Typical values ​​are as follows: the aerobic mixing period is 15% of the aerobic reaction phase; preset time period one: the first 5% to 15% of the aerobic reaction phase (i.e., 5% to 15% of the total aerobic reaction phase time; the start time of preset time period one is "the start time of the aerobic reaction phase + 5% of the total aerobic reaction phase time"; the end time of preset time period one is "the start time of the aerobic reaction phase + 15% of the total aerobic reaction phase time"); data are collected at intervals of 1 to 5 minutes and averaged. Stable aerobic reaction stage (mid-to-late stage of aeration): After mixing, the reactor enters a stable aerobic reaction stage, which is also the main stage of organic matter degradation and nitrification. At this time, the aeration intensity can be finely adjusted according to the feedback from the online DO meter, the water turbulence is reduced, the sludge bed enters a dynamic equilibrium state, and the water quality indicators and sludge state change stably with the reaction process.

[0057] Aerobic transition phase (before aeration ends): A transition phase is set up before the sedimentation stage begins after aeration ends. During this phase, the aeration intensity is gradually reduced or intermittent aeration is used to allow the sludge bed to regain some settling properties and prevent the sludge flocs from being broken up due to excessive aeration, which would affect the subsequent sludge-water separation effect.

[0058] Preset Time Period Two: The first 35% to 45% of the aerobic reaction stage; organic matter degradation and nitrification have entered a stable phase, and the sludge bed is in dynamic equilibrium. The start time of Preset Time Period Two is "the start time of the aerobic reaction stage + 35% of the total aerobic reaction stage duration"; the end time of Preset Time Period Two is "the start time of the aerobic reaction stage + 45% of the total aerobic reaction stage duration". (3) Determine the reference turbidity I, reference turbidity II, and reference turbidity III based on the detection values ​​of turbidity detection device I, turbidity detection device II, and turbidity detection device III within a preset time period; The reference turbidity is the average detection value of the turbidity detection device within a preset time period. Reference turbidity 2 is the average detection value of turbidity detection device 2 within a preset time period 1; Reference turbidity 3 is the average detection value of turbidity detection device 3 within a preset time period 1; (4) The allowable range of the reference parameters is a reasonable range obtained by statistically analyzing the stable data of the mixing section collected continuously over multiple cycles under normal operating conditions (the wastewater is treated to be qualified and the reactor is operating normally). For example, the allowable range of the reference turbidity is ±20% of the historical average reference turbidity value under the same influent source and stable operating conditions of this system; it can also be dynamically corrected according to the influent water quality, sludge concentration and process requirements.

[0059] Upon receiving an alarm, the system can execute tiered handling measures according to preset logic, including but not limited to: It issues audible, visual, and remote alarm signals to prompt operators to check the influent water quality, sludge condition, and equipment operation; it automatically extends the aerobic mixing period, appropriately increases the aeration intensity, and observes whether the baseline parameters return to normal; if the baseline parameters remain abnormal for multiple consecutive cycles, it automatically locks the current operating program, stops subsequent process steps, and triggers shutdown protection to prevent unqualified effluent discharge or further deterioration of system conditions.

[0060] (5) Relative turbidity difference between the lower and middle layers: (average detection value of turbidity detection device 3 within the preset time period 2 - average detection value of turbidity detection device 2 within the preset time period 2) ÷ average detection value of turbidity detection device 2 within the preset time period 2, reflecting the suspension state and aeration disturbance intensity of the sludge bed; The current upper turbidity deviation value is: "average detection value of turbidity detection device 1 within the preset time period 2 - reference turbidity 1 determined in step 401", which reflects the degree of particle entrainment in the upper region of the reactor and predicts the risk of sludge run-off in the subsequent sedimentation stage. DO fluctuation coefficient: The ratio of the standard deviation to the mean value of DO data continuously collected within a preset time period, which reflects the stability of the system's oxygen supply status.

[0061] (6) The allowable / normal range of the key analytical parameters is a reasonable range determined by experiments and historical data based on the reactor operating under qualified wastewater treatment conditions; the warning range is partly set near the limit within the normal range and partly set near the boundary outside the normal range, serving as a control trigger condition. Typical examples are as follows: 1. Relative turbidity difference between the lower and middle layers: The allowable / normal range is: Under normal operating conditions (e.g., MLSS ≥ 3000 mg / L): (0.15, 0.25); Low sludge concentration conditions (e.g., MLSS < 3000 mg / L): (0.1, 0.2); The warning range is: Normal operating conditions: [0.25, 0.4], (0, 0.15]; Low sludge concentration conditions: [0.2, 0.3], (0, 0.1]; This parameter reflects the suspension state of the sludge bed and the intensity of aeration disturbance.

[0062] When the relative turbidity difference between the lower and middle layers is greater than 40% or less than or equal to 0, it exceeds the warning control range, triggers a system alarm, and stops the aeration parameter correction.

[0063] 2. Current upper layer turbidity deviation value: The permissible / normal range is: not exceeding 0.2 times the reference turbidity; The warning range is: when the turbidity reaches 0.15 times the baseline turbidity, or when the turbidity increases by 8% of the baseline turbidity within 5 minutes; This deviation reflects the change in the degree of particle entrainment in the upper region. If it exceeds the allowable / normal range, it indicates that there may be a risk of sludge bulking or sludge leakage, which requires close attention.

[0064] 3. DO volatility coefficient: The normal range is: Medium-to-high nitrogen wastewater operating condition: ≤0.10; Low-nitrogen wastewater condition: ≤0.15; The warning range is set below the normal range and close to the critical value: Medium-to-high nitrogen wastewater operating conditions: reaching 0.08; Low-nitrogen wastewater condition: reaches 0.12.

[0065] The above allowable range can be dynamically adjusted based on the actual influent water quality, sludge concentration, and process operation requirements.

[0066] The apparent aeration rise rate is a parameter calculated internally by the controller, which is equal to the aeration volume flow rate divided by the reactor cross-sectional area. The aeration volume flow rate is collected in real time by a gas flow meter installed on the aeration pipe, and the reactor cross-sectional area is a fixed geometric parameter of the reactor. The controller calculates the apparent aeration rise rate based on the collected aeration volume flow rate. In practice, the apparent aeration rise rate is adjusted by regulating the aeration volume flow rate output by the blower.

[0067] The turbidity co-control embodiment of this example does not start detection from the beginning of system startup, nor does it calibrate the permanent installation position once. Instead, it is a dynamic monitoring mechanism specifically designed for the slow drift of the sludge bed interface during continuous long-term operation. The aforementioned relative height benchmark of 100-300mm is determined based on the initial stable state of the specific device in each specific application scenario and the specific continuous operation cycle, and can be adaptively adjusted according to the actual sludge bed height in the current period.

[0068] The beneficial effects of this implementation plan are as follows: 1. By dividing the column-type sequencing batch reactor into an upper effluent zone, a middle aeration and mixing zone, and a lower sludge enrichment zone, and by specifically installing three turbidity detection devices and a middle online DO meter, the sludge-water state in different zones can be monitored: Turbidity detection device 1 (upper effluent zone): Real-time reflection of particle entrainment in the upper zone, predicting the risk of subsequent sludge runoff. Turbidity detection device 2 (middle and lower boundary): Reflects the overall suspension height of the granular sludge bed, determining whether the aeration disturbance intensity is reasonable, providing a basis for preventing excessive expansion or compaction of the sludge bed. Turbidity detection device 3 (lower sludge enrichment zone): Directly reflects the density and stability of the granular sludge bed, determining whether there is local anoxic conditions or uneven fluidization, ensuring the stability of the denitrification reaction zone. Online DO meter (middle aeration and mixing zone): Directly reflects the oxygen supply intensity and uniformity, providing data support for calculating the DO fluctuation coefficient and controlling oxygen supply stability.

[0069] 2. The aerobic reaction phase is divided into an aerobic mixing phase, a stable aerobic reaction phase, and a transition phase at the end of the aerobic period, with preset time periods one and two, achieving refined operation "phased and targeted": Aerobic mixing section and preset time period one: In the initial stage of aeration, the static state of the granular sludge bed is broken by a high aeration intensity, so that the sludge and water are fully mixed and a uniform flow field is established; the turbidity data collected in preset time period one is averaged as the benchmark value, which provides a stable reference for subsequent deviation calculation that is not affected by the initial fluctuations, and avoids misjudgment caused by the initial disturbance.

[0070] Stable aerobic reaction stage and preset time period two: In the middle and late stages of aeration, the reactor enters the main stage of organic matter degradation and nitrification. At this time, the water turbulence weakens and the sludge bed enters dynamic equilibrium. Preset time period two is in the first 35% to 45% of the aerobic reaction stage. At this time, the reaction process is stable and the parameter changes are gradual. It is the best window for coordinated control, which avoids the interference of initial fluctuations and also reserves sufficient time for subsequent adjustments.

[0071] The aerobic transition stage: By gradually reducing the aeration intensity or switching to intermittent aeration, the sludge bed is allowed to regain its settling properties, avoiding the flocs from being broken up due to excessive aeration, thus ensuring the subsequent sludge-water separation effect and reducing the suspended solids content in the effluent.

[0072] 3. Steps 401-402 collect turbidity data for a preset time period to determine baseline turbidity levels one, two, and three, and set allowable ranges for baseline parameters and a tiered alarm mechanism, thus enabling early intervention for abnormalities in the mixing section. Establishment of baseline turbidity: A baseline is established based on stable data from the mixing section, providing a reliable zero point for subsequent deviation calculations. This avoids the lag caused by using historical averages as a baseline and can quickly adapt to changes in different influent water quality and sludge concentrations.

[0073] The allowable range of benchmark parameters is determined based on experimental and historical data under qualified wastewater treatment conditions, ensuring the rationality and reliability of the benchmark parameters.

[0074] Tiered alarm and handling measures: By using audible and visual / remote alarms, extending the mixing section duration, and automatically locking the program, abnormalities in the mixing section can be effectively addressed, unqualified effluent discharge can be avoided, and the safe operation of the system can be ensured.

[0075] 4. Steps 403-404 involve collecting data during a preset time period, calculating the relative turbidity difference between the lower and middle layers, the turbidity deviation value of the upper layer, and the DO fluctuation coefficient, and setting an early warning range to achieve risk prediction for the stable aerobic phase. The relative turbidity difference between the lower and middle layers: The difference between the turbidity detection device three and device two directly reflects the suspension state of the sludge bed and the intensity of aeration disturbance. It can quickly identify excessive sludge suspension caused by excessive aeration or sludge bed compaction caused by insufficient aeration, providing a direct basis for sludge bed state control.

[0076] Upper layer turbidity deviation value: The difference between the current upper layer turbidity and the reference turbidity reflects the change in the degree of particle entrainment in the upper region. Combined with the dual warning of static deviation and dynamic rise, it can detect the risk of sludge bulking or sludge leakage in advance and avoid the deterioration of effluent water quality.

[0077] DO fluctuation coefficient: The ratio of the standard deviation to the mean of DO data reflects the stability of oxygen supply. It can identify large fluctuations in DO caused by unreasonable aeration rhythm and avoid decreased nitrification efficiency or over-aeration.

[0078] 5. Steps 405-406 dynamically adjust the apparent aeration rise rate and aeration gap duty cycle using a graded correction rule based on the early warning status, achieving multi-parameter synergistic optimization and avoiding the limitations of adjusting a single parameter. Lower and middle layer relative turbidity difference correction: By judging the warning range, distinguish between two operating conditions of excessive and insufficient aeration, and adjust the apparent aeration rise rate and duty cycle respectively, so as to quickly restore the sludge bed to a stable suspended state without affecting the reaction process, ensuring the sludge-water mixing effect and the stability of the subsequent denitrification zone.

[0079] Upper layer turbidity deviation correction: For both static deviation and dynamic rise, the aeration gap duty cycle is adjusted first, and if necessary, the apparent aeration rise rate is reduced simultaneously. This reduces floc shearing from both the aeration rhythm and intensity, lowers the risk of sludge runoff, and ensures the quality of the effluent.

[0080] DO fluctuation coefficient correction: Adjust the aeration interval duty cycle only for the fluctuation itself, and smooth DO fluctuation by optimizing the aeration start and stop rhythm, without affecting the average DO level, and ensuring the stable progress of nitrification reaction.

[0081] Priority correction rule: Correction is carried out in the order of "upper layer turbidity deviation value → DO fluctuation coefficient → lower and middle layer relative turbidity difference". Priority is given to controlling the risk of sludge runoff, then ensuring the stability of oxygen supply, and finally fine-tuning the sludge suspension state. This avoids parameter adjustment conflicts and ensures that the correction direction is consistent with the process objectives.

[0082] Single adjustment range limit: The single adjustment range shall not exceed ±15% of the current value, which avoids drastic fluctuations in operating conditions caused by large adjustments and ensures a smooth transition of the system.

[0083] 6. This solution achieves refined and intelligent control of the granular sludge SBR process through a complete closed loop of "zonal monitoring → segmented operation → baseline establishment → risk warning → collaborative correction." It overcomes the limitations of traditional SBRs that rely solely on DO or time-based program control, achieving comprehensive regulation of sludge bed status, effluent particle entrainment, and oxygen supply stability through multi-parameter synergy of turbidity and DO, thereby enhancing the system's resistance to shock loads. Relying on a preset time-period sampling and early warning mechanism, it achieves dynamic correction based on real-time operating conditions, abandoning fixed-sequence operation modes and adapting to fluctuations in influent water quality and sludge status, ensuring stable effluent quality compliance. While ensuring nitrogen and phosphorus removal effects, it reduces particle breakage caused by excessive aeration, which is beneficial for maintaining the integrity and settling performance of granular sludge. Graded early warning combined with progressive parameter correction achieves refined process control, reduces aeration energy consumption, and improves system operating efficiency.

[0084] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A cycle-optimized aerobic granular sludge wastewater treatment method, characterized in that: include: Step 1: Anaerobic influent stage: Pump the wastewater to be treated into the column-type sequencing batch reactor to complete the anaerobic influent stage; Step 2: Anaerobic reaction stage: After the influent is finished, the anaerobic reaction stage begins. During the anaerobic reaction stage, mechanical stirring at 18-22 rpm is used to maintain DO < 0.5 mg / L; Step 3: Aerobic reaction stage: After the anaerobic stage ends, switch to aerobic aeration mode: Turn on the microporous aerator at the bottom of the column-type sequencing batch reactor and control the apparent aeration rise rate to 1-1.5 cm / s to maintain the DO concentration in the column-type sequencing batch reactor at 2-4 mg / L. Step 4: When dealing with medium-to-high nitrogen wastewater, execute the anoxic reaction stage: After the aerobic stage, aeration is stopped and the system is switched to anoxic stirring mode: mechanical stirring at 18-22 rpm is used to maintain DO < 0.5 mg / L, and denitrification is carried out using the nitrates remaining from the aerobic stage. Step 5: Settling and Screening Stage After the reaction stage is completed, aeration and stirring are stopped, and the sludge-water separation stage begins. The drainage control parameters for the current operating cycle are determined based on the growth stage of the granular sludge. Step 6: Drainage stage: After settling, drain the water and control the volume exchange ratio to 50%; after drainage, enter the next operating cycle.

2. The periodically optimized aerobic granular sludge wastewater treatment method according to claim 1, characterized in that: Drainage control parameters include hydraulic upflow velocity; Start-up phase: Drainage begins 20 minutes after the sedimentation phase starts, with a hydraulic upflow velocity >1.5 m / h during the drainage phase; Granulation period: Drainage is carried out 10 minutes after the start of the sedimentation stage, and the hydraulic upflow velocity during the drainage stage is >3m / h; Maturation stage: Drainage begins 5 minutes after the start of the sedimentation stage, with a hydraulic upflow velocity of >6m / h during the drainage stage.

3. The periodically optimized aerobic granular sludge wastewater treatment method according to claim 1, characterized in that: Column-type sequencing batch reactor with a height-to-diameter ratio of 8-12:

1.

4. The periodically optimized aerobic granular sludge wastewater treatment method according to claim 1, characterized in that: Throughout each operating cycle, the reactor temperature is controlled at 28±2℃.

5. The periodically optimized aerobic granular sludge wastewater treatment method according to claim 1, characterized in that: The total runtime of the operation cycle is 6 hours. For medium- and high-nitrogen wastewater, an A / O / A cycle is adopted, with the aerobic reaction time accounting for more than 55% of the total time of a single operating cycle, and the anoxic reaction time accounting for 5%-10% of the total time of a single operating cycle. For low-nitrogen wastewater, an A / O cycle is adopted, with the aerobic reaction time accounting for more than or equal to 65% of the total time of a single operating cycle.

6. The periodically optimized aerobic granular sludge wastewater treatment method according to claim 1, characterized in that: Influent water quality control: COD concentration 500-600 mg / L, NH4+ + -N concentration 40-60 mg / L, PO4 3- -P concentration is 8-12 mg / L, pH is 7.5±0.2, and 1 mL of trace element solution containing Fe, Mn and Zn is added per liter of influent.

7. The periodically optimized aerobic granular sludge wastewater treatment method according to claim 1, characterized in that: The start-up period is 1-16 days after the column-type sequencing batch reactor (SBR) is inoculated with sludge; the granulation period is 17-31 days after the column-type SBR is inoculated with sludge; and the maturity period is 32-94 days after the column-type SBR is inoculated with sludge.

8. The periodically optimized aerobic granular sludge wastewater treatment method according to claim 1, characterized in that: During the A / O / A cycle, the duration of the anoxic reaction phase is dynamically adjusted according to the influent TN concentration: when the influent TN concentration is >50mg / L, the duration of the anoxic reaction phase is 10% of the total duration of a single operating cycle; when the influent TN concentration is 30-50mg / L, the duration of the anoxic reaction phase is 5%-10% of the total duration of a single operating cycle; when the influent TN concentration is <30mg / L, the cycle is switched to A / O.

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