Quantitative regulation and control method for satiation-starvation ratio and continuous flow aerobic granular sludge system

Abstract

The invention provides a quantitative regulation and control method for a satiation starvation ratio and a continuous flow aerobic granular sludge system, and relates to the field of continuous flow aerobic granular sludge culture. The continuous flow aerobic granular sludge system comprises a reaction tank, the reaction tank comprises a satiation area and a starvation area, and the method comprises the following steps: calculating real-time inflow water organic load according to real-time inflow water flow and real-time inflow water chemical oxygen demand concentration of the reaction tank; calculating the sludge concentration of an ideal satiation area according to the critical food / micro ratio and the real-time water inlet organic load; calculating the ideal sludge reflux quantity of the satiation area according to the real-time water inlet flow and the ideal sludge concentration and the sludge reflux concentration of the satiation area; and regulating the sludge reflux quantity of the satiation area until the sludge reflux quantity is the same as the ideal sludge reflux quantity. The problem that the satiation hunger ratio cannot be quantitatively calculated and regulated in the prior art, so that the satiation hunger effect of the system is poor is solved.

Description

Technical Field

[0001] The present application relates to the field of continuous flow aerobic granular sludge cultivation, and in particular to a quantitative control method of a satiety-hunger ratio and a continuous flow aerobic granular sludge system. Background Art

[0002] Aerobic granular sludge is a granular activated sludge formed by microbial self-agglomeration, which has the advantages of good sedimentation performance, high biomass and simultaneous removal of carbon, nitrogen and phosphorus. A large number of literature reports that the periodic satiation-starvation environment is conducive to the enrichment of slow-growing microorganisms (such as PAO and GAO) that store internal carbon sources, thereby promoting granulation. At present, the engineering application of aerobic granular sludge technology has been successfully realized in the sequencing batch reactor activated sludge process (SBR) reactor by controlling the satiation / starvation alternation, hydraulic selective pressure and other granulation strategies. However, due to the fact that the aerobic granular sludge technology is easy to directly mix with the influent in the continuous flow reactor, it leads to low mass transfer efficiency and the water quality and water volume are difficult to control, making it difficult to achieve a relatively stable satiation-starvation environment.

[0003] In the existing technology, certain satiety and hunger conditions are mostly created qualitatively by regulating the water inlet method or sludge return strategy. However, there are few applied studies on satiety and hunger conditions, and it is impossible to quantitatively calculate and regulate the satiety-hunger ratio, resulting in poor satiety-hunger effect of the system, which in turn affects the granulation process of the continuous flow aerobic granular sludge system.

[0004] Existing studies have shown through theoretical derivation that the satiety-starvation ratio is a function of the number of reactor chambers and the Damköhler number (Da), and Da depends on the feed-microorganism ratio (F / M). Therefore, for a continuous flow aerobic granular sludge system with a certain reactor structure and influent water quality, F / M is the main factor affecting the satiety-starvation ratio. Summary of the invention

[0005] The present application provides a quantitative control method of the satiety-hunger ratio and a continuous flow aerobic granular sludge system, which are used to solve the problem that in the prior art, certain satiety-hunger conditions are qualitatively created by mostly using the water inlet method or setting up sludge return, but there are few applied studies on the satiety-hunger conditions, and it is impossible to quantitatively calculate and control the satiety-hunger ratio, resulting in a poor satiety-hunger effect of the system, which in turn affects the granulation process of the continuous flow aerobic granular sludge system.

[0006] In a first aspect, the present application provides a method for quantitatively controlling a satiety-hunger ratio. The continuous flow aerobic granular sludge system includes a reaction tank, and the reaction tank includes a satiety zone and a hunger zone. The method includes:

[0007] The real-time influent organic load is calculated based on the real-time influent flow rate and real-time influent chemical oxygen demand concentration of the reaction tank;

[0008] According to the critical feed-micro ratio and the real-time influent organic load, the ideal sludge concentration in the saturation zone is calculated;

[0009] According to the real-time influent flow rate, the ideal sludge concentration in the saturated zone and the sludge return concentration, the ideal sludge return flow rate in the saturated zone is calculated;

[0010] The sludge return flow rate in the saturation zone is adjusted until the sludge return flow rate is the same as the ideal sludge return flow rate.

[0011] In one possible design, the reaction tank includes a plurality of partitions, the plurality of partitions including: an anaerobic zone, an anoxic zone, and an aerobic zone;

[0012] Before calculating the real-time influent organic load according to the real-time influent flow rate and the real-time influent chemical oxygen demand concentration of the reaction tank, the method further includes:

[0013] According to the total hydraulic retention time and the first satiety-hunger ratio, a satiety-hunger ratio critical position is obtained, and the plurality of zones are divided into satiety zones and hunger zones according to the satiety-hunger ratio critical position; wherein the first satiety-hunger ratio is selected from a preset satiety-hunger ratio interval;

[0014] Increasing the chemical oxygen demand concentration of the influent, and obtaining multiple parameter values ​​when the sludge return ratio of the saturated zone, the sludge concentration of the anaerobic zone, the chemical oxygen demand concentration at the critical position of the saturated-hunger ratio, and the change value of the chemical oxygen demand concentration at the critical position of the saturated-hunger ratio meet their respective preset critical conditions; wherein the multiple parameter values ​​include: critical chemical oxygen demand concentration, influent flow, activated sludge concentration in the anaerobic zone, and reaction tank volume in the saturated zone;

[0015] The critical prey-microbe ratio is calculated based on multiple parameter values.

[0016] In one possible design, each partition is equally divided into a plurality of chambers, and the total hydraulic retention time comprises: a chamber hydraulic retention time of each chamber, wherein the total hydraulic retention time and the chamber hydraulic retention time are both time periods;

[0017] According to the total hydraulic retention time and the first satiety-hunger ratio, the critical position of the satiety-hunger ratio is obtained, including:

[0018] According to the first satiety-hunger ratio and the total hydraulic retention time, the hydraulic retention time point corresponding to the first satiety-hunger ratio is obtained;

[0019] The chamber where the hydraulic retention time point is located is taken as the critical position of the satiety-hunger ratio.

[0020] In a possible design, the preset critical conditions include: a sludge return ratio range in the satiety zone, a sludge concentration range in the anaerobic zone, a chemical oxygen demand concentration threshold at a satiety-hunger ratio critical position, and a chemical oxygen demand concentration change threshold at a satiety-hunger ratio critical position;

[0021] The critical position of satiety-hunger ratio is the terminal chamber of the satiety zone, and the chamber of the hunger zone adjacent to the terminal chamber is the front chamber of the hunger zone;

[0022] The critical position of the satiety-hunger ratio is located at the end of the multiple chambers in the satiety zone, wherein the end of the multiple chambers in the satiety zone is on the same side as the front end of the multiple chambers in the hunger zone.

[0023] In a possible design, when the sludge return ratio of the satiety zone, the sludge concentration of the anaerobic zone, the chemical oxygen demand concentration at the satiety-hunger ratio critical position, and the change value of the chemical oxygen demand concentration at the satiety-hunger ratio critical position meet their respective preset critical conditions, multiple parameter values ​​are obtained, including:

[0024] Regulating the sludge return ratio and the sludge concentration until the sludge return ratio meets the sludge return ratio range and the sludge concentration meets the sludge concentration range, and then maintaining the regulated sludge return ratio and sludge concentration;

[0025] The chemical oxygen demand concentration of the influent is gradually increased. During this period, the real-time chemical oxygen demand concentration of the influent, as well as the chemical oxygen demand concentration, influent flow rate and activated sludge concentration of the terminal chamber and the front chamber at each moment are recorded;

[0026] When the chemical oxygen demand concentration of the terminal chamber is less than the chemical oxygen demand concentration threshold, and the chemical oxygen demand concentration change value between the chemical oxygen demand concentration of the terminal chamber and the chemical oxygen demand concentration of the front chamber is less than the chemical oxygen demand concentration change threshold, the real-time inlet chemical oxygen demand concentration at the first moment is taken as the critical chemical oxygen demand concentration; wherein the first moment is the moment before the second moment; the second moment is the moment when the chemical oxygen demand concentration of the terminal chamber is greater than or equal to the chemical oxygen demand concentration threshold, or the chemical oxygen demand concentration change value is greater than or equal to the chemical oxygen demand concentration change threshold.

[0027] In a possible design, after the sludge return rate of the saturated zone is regulated until the sludge return rate is equal to the ideal sludge return rate, the method further comprises:

[0028] Regularly test the real-time satiety-hunger ratio, adjust the real-time satiety-hunger ratio according to the requirements of different granular sludge culture stages, and update the critical food-micro ratio.

[0029] In a second aspect, the present application provides a continuous flow aerobic granular sludge system, the system comprising: a reaction tank;

[0030] The reaction pool includes a plurality of partitions, and the plurality of partitions are divided into a satiation zone and a hunger zone;

[0031] Multiple zones include: anaerobic, anoxic, and aerobic zones;

[0032] One end of the anaerobic zone is on the same side as the other end of the anoxic zone, and one end of the aerobic zone is on the same side as the other end of the anaerobic zone and the other end of the anoxic zone.

[0033] In a possible design, the anaerobic zone and the anoxic zone both include: a plurality of chambers, partition walls, water holes and a stirring device; each chamber is obtained by evenly dividing the anaerobic zone or the anoxic zone by the partition walls, each partition wall is provided with a water hole, and the liquid between two adjacent chambers is connected through the water hole; each compartment of the anaerobic zone is provided with a baffle of a certain height, and each chamber of the anoxic zone is provided with a stirring device;

[0034] The aerobic zone is connected with the anaerobic zone and the anoxic zone through water holes. The aerobic zone includes: multiple aerobic tanks, baffles, microporous aeration devices and stirring devices; each aerobic tank is obtained by evenly dividing the aerobic zone through baffles.

[0035] In one possible design, the system further includes: a precipitation device and a reflux device;

[0036] One end of the sedimentation device is on the same side as the other end of the aerobic zone, and the sedimentation device includes: a guide plate, a sludge return hopper, a sludge external discharge hopper, a sludge sedimentation area and a sludge scraping device; the guide plate is arranged between the top and the middle of the sedimentation device, the sludge return hopper is arranged at the bottom of the water inlet end of the sedimentation device, the sludge external discharge hopper is arranged at the bottom of the water outlet end of the sedimentation device, and the sludge scraping device is arranged in the sludge sedimentation area in the middle of the sedimentation device; the guide plate and the sludge return hopper are jointly arranged at the front end of the sedimentation device, and the sludge scraping device is arranged in the sludge sedimentation area located in the middle of the sedimentation device;

[0037] The reflux device comprises a nitrification liquid reflux device and a sludge reflux device. The nitrification liquid reflux device is respectively connected to the aerobic zone outlet and the anaerobic zone and the anoxic zone. The sludge reflux device is respectively connected to the sludge reflux hopper and the anaerobic zone inlet.

[0038] In a possible design, the dissolved oxygen concentration in the anaerobic zone should be maintained below 0.05 mg / L, the redox potential in the anaerobic zone should be maintained at -150 to -225 mV, the dissolved oxygen concentration at the outlet of the aerobic zone should be maintained below 0.5 mg / L, and the concentration of the sludge return hopper in the sedimentation tank should be maintained above 12,000 mg / L.

[0039] In one possible design, the system further includes an intelligent control device;

[0040] The intelligent control device is connected to the stirring device by signal, and is used to control the switch of the stirring device and the stirring rate; the intelligent control device is connected to the reflux pump of the reflux device by signal, and is used to adjust the switch of the reflux pump and the reflux flow rate. The intelligent control device is connected to the microporous aeration device by signal, and is used to control the switch of the microporous aeration device and the aeration flow rate;

[0041] The intelligent control device is respectively connected to the online monitoring devices of the anaerobic zone, the anoxic zone, the aerobic zone and the precipitation device by signals.

[0042] In a possible design, the outlet section of the aerobic zone is equipped with a microporous aeration device and a stirring device. The stirring device is turned on for a long time, and the start and stop of the microporous aeration device in the outlet section is regulated according to the signal transmitted by the online monitoring equipment of the aerobic zone.

[0043] The present application provides a quantitative control method of a satiation-starvation ratio and a continuous flow aerobic granular sludge system, wherein the continuous flow aerobic granular sludge system includes a reaction tank, the reaction tank includes a satiation zone and a starvation zone, and the real-time influent organic load is calculated according to the real-time influent flow rate and the real-time influent chemical oxygen demand concentration of the reaction tank; the ideal sludge concentration in the satiation zone is calculated according to the critical feed-micro ratio and the real-time influent organic load; the ideal sludge return volume in the satiation zone is calculated according to the real-time influent flow rate, the ideal sludge concentration in the satiation zone and the sludge return concentration; the sludge return volume in the satiation zone is regulated until the sludge return volume is the same as the ideal sludge return volume. Compared with the prior art, certain satiation-starvation conditions are qualitatively created from the water inlet method or the sludge return setting, but there are few applied studies on satiation-starvation conditions, and it is impossible to quantitatively calculate and regulate the satiation-starvation ratio, resulting in poor satiation-starvation effect of the system, which in turn affects the granulation efficiency of the continuous flow aerobic granular sludge system. This application is based on the regulation strategy of the critical position of the satiety-hunger ratio, which regulates the system's satiety-hunger ratio within a set range, greatly improving the stability of the satiety-hunger environment in the continuous flow system and providing the possibility for the rapid cultivation of AGS in the continuous flow system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A schematic diagram of a continuous flow aerobic granular sludge system provided in an embodiment of the present application Figure 1 ;

[0046] Figure 2 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 1 ;

[0047] Figure 3 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 2 ;

[0048] Figure 4 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 3 ;

[0049] Figure 5 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 4 .

[0050] Reference numerals:

[0051] 100-Continuous flow aerobic granular sludge system;

[0052] 110- anaerobic zone; 120- anoxic zone; 130- aerobic zone; 140- sedimentation device;

[0053] 111-chamber; 112-partition wall; 114-stirring device;

[0054] 131- aerobic tank; 132- baffle plate; 133- microporous aeration device;

[0055] 141-guide plate; 142-sludge return hopper; 143-sludge discharge hopper; 144-sludge sedimentation area; 145-sludge scraping device. DETAILED DESCRIPTION

[0056] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0057] In the embodiments of the present application, words such as "first" and "second" are used to distinguish the same or similar items with basically the same functions and effects. Those skilled in the art will understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit the difference. It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way. In the embodiments of the present application, "at least one" refers to one or more, and "more" refers to two or more.

[0058] It should be noted that the "at..." in the embodiments of the present application can be the instant when a certain situation occurs, or can be a period of time after a certain situation occurs, and the embodiments of the present application do not specifically limit this. In addition, the quantitative control method of the satiety-hunger ratio and the continuous flow aerobic granular sludge system provided in the embodiments of the present application are only used as examples, and the quantitative control method of the satiety-hunger ratio can also include more or less content.

[0059] In order to clearly describe the technical solutions of the embodiments of the present application, some terms and technologies involved in the embodiments of the present application are briefly introduced below:

[0060] Aerobic Granular Sludge (AGS): Aerobic granular sludge is granular activated sludge formed by microbial self-agglomeration. It has a dense structure, good sedimentation performance and excellent decontamination ability.

[0061] Feast-starvation conditions are a stressor that can cause changes in microbial populations, also known as microbial selection pressure. During the feast phase, readily biodegradable substrates accumulate in the form of polymers in slow-growing microorganisms. Subsequently, during the starvation phase, these stored polymers become a resource for microbial growth. Studies have found that alternating feast-starvation conditions stimulate EPS secretion and enhance surface hydrophobicity, thereby promoting microbial aggregation. In addition, feast-starvation conditions tend to favor the proliferation of slow-growing bacteria such as glycogen-accumulating organisms (GAOs), polyphosphate-accumulating organisms (PAOs), and denitrifying phosphorus-accumulating organisms (DPAOs), which helps improve nutrient removal performance and promote long-term stability.

[0062] Food-microbe ratio (F / M): also called sludge load, is a ratio that reflects the relationship between the number of food and microorganisms. The size of the food-microbe ratio will directly affect the growth rate of activated sludge, the removal rate of organic pollutants, the oxygen utilization rate and the sedimentation performance of sludge. In the continuous flow aerobic granular sludge system, if F / M is too large, the organic matter in the influent cannot be fully absorbed in the saturated zone and enter the aerobic zone, resulting in the massive reproduction of ordinary heterotrophic microorganisms, and the sludge sedimentation is difficult to improve. In severe cases, it will also cause filamentous bacteria to swell; if F / M is too small, the functional microorganisms in the anaerobic zone cannot fully absorb organic matter to grow and reproduce, and the granular sludge is difficult to form, which will also affect the nitrogen removal and phosphorus removal efficiency of the system.

[0063] Compared with traditional activated sludge process, AGS can save 50% to 75% of floor space, 20% to 25% of operating costs and 23% to 40% of electricity consumption.

[0064] However, since the incoming water in the continuous flow reactor is easily mixed directly and the water volume is difficult to control, it is difficult to achieve a relatively stable satiety-hunger environment. It is also difficult to gradually reduce the sludge settling time to exert selective pressure on the activated sludge and the reflow method of granular sludge as in the sequencing batch reactor. It is impossible to quickly achieve sludge granulation and stable operation of the granular sludge system in the continuous flow reactor, resulting in the current promotion and application of AGS in the continuous flow field has not made substantial breakthroughs.

[0065] At present, most of the applied research on satiation-starvation conditions qualitatively creates certain satiation-starvation conditions from the water inlet method or setting up sludge return, but has not yet quantitatively calculated and regulated the system's satiation-starvation ratio by using parameters such as the influent organic load; in addition, it is currently difficult to form an ideal plug flow state in the anaerobic zone of the sewage treatment plant, and the rapid mixing of the influent causes further dilution of the organic matter concentration, resulting in poor satiation-starvation effect of the system.

[0066] Based on this, in order to solve the above technical problems, the embodiment of the present application provides a quantitative control method of the satiety-hunger ratio and a continuous flow aerobic granular sludge system, which can be used in the field of continuous flow aerobic granular sludge cultivation. The inventive concept of the present application is: how to effectively improve the granulation efficiency of the continuous flow aerobic granular sludge system.

[0067] Figure 1 A schematic diagram of a continuous flow aerobic granular sludge system provided in an embodiment of the present application Figure 1 .like Figure 1 As shown, the continuous flow aerobic granular sludge system 100 includes an anaerobic zone 110, an anoxic zone 120, an aerobic zone 130, a sedimentation device 140, and a reflow device.

[0068] like Figure 1As shown, the dotted lines divide the continuous flow aerobic granular sludge system 100 into a plurality of chambers 111 , wherein the four chambers in the upper left corner are anaerobic zones 110 , the four chambers in the upper right corner are anoxic zones 120 , the six chambers in the lower right corner are aerobic zones 130 , and the lower left corner is a sedimentation device 140 .

[0069] It can be understood that the dotted boxes outside the anaerobic zone 110, the anoxic zone 120, the aerobic zone 130 and the sedimentation device 140 in the figure are only used to distinguish different areas and are not used as real area boundaries.

[0070] The anaerobic zone 110 , the anoxic zone 120 and the aerobic zone 130 constitute a reaction pool, and the reaction pool is divided into a satiety zone and a hunger zone according to a critical position of a satiety-hunger ratio.

[0071] Specifically, one end of the anaerobic zone 110 is on the same side as the other end of the anoxic zone 120 , and one end of the aerobic zone 130 is on the same side as the other end of the anaerobic zone 110 and the other end of the anoxic zone 120 .

[0072] The anaerobic zone 110 and the anoxic zone 120 both include: a plurality of chambers, partition walls, water holes and a stirring device.

[0073] For example, Figure 1 The chamber, partition wall, water hole and stirring device in the anaerobic zone 110 are described as an example. For the chamber, partition wall, water hole and stirring device in the anoxic zone 120, reference can be made to Figure 1 The description of the anaerobic zone 110 is given in detail, and the specific structure of the anoxic zone 120 is not repeated here.

[0074] Among them, Figure 1 The middle part of the structure is used as an example to illustrate that the partition wall is Figure 1 The chamber is marked as 112. Figure 1 The stirring device is marked as 111. Figure 1 The number is marked as 114.

[0075] Each chamber 111 is obtained by evenly dividing the anaerobic zone 110 or the anoxic zone 120 by a partition wall 112. Each partition wall 112 is provided with two water holes, one above and one below. The liquid between two adjacent chambers 111 is connected through the water holes. Each chamber 111 is provided with a stirring device 114.

[0076] For example, the hydraulic retention time of each chamber of the anaerobic zone 110 and the anoxic zone 120 is controlled within 30 minutes.

[0077] For example, the DO concentration of each chamber 111 of the anaerobic zone 110 is maintained at 0-0.05 mg / L by controlling the dissolved oxygen concentration at the outlet of the aerobic zone, while the DO concentration of each chamber 111 of the anoxic zone 120 is maintained at 0.2-0.8 mg / L.

[0078] The aerobic zone 130 is connected to the anaerobic zone 110 and the anoxic zone 120 through water holes. The aerobic zone includes: a plurality of aerobic tanks 131, baffles 132, microporous aeration devices 133 and outlet zone stirring devices 134.

[0079] Each aerobic pool 131 is obtained by evenly dividing the aerobic zone through the baffle plate 132.

[0080] For example, the aerobic zone 130 controls the DO concentration at the front and middle ends of the aerobic pool 131 to be 1.5-4.5 mg / L by the opening and closing degree of the air inlet solenoid valve. A stirring device is also provided in the water outlet section and is started for a long time. The intelligent control device controls the opening and closing of the air inlet solenoid valve at the water outlet of the microporous aeration device according to the ammonia nitrogen concentration at the water outlet of the aerobic zone.

[0081] Specifically, in order to avoid the introduction of a large amount of oxygen from the aerobic tank to the anaerobic tank and the anoxic tank during the sludge backflow and the nitrification liquid backflow process, which affects the DO concentration of the anaerobic tank and the anoxic tank, thereby affecting the absorption of organic matter in the influent by functional microorganisms such as polyphosphate-accumulating bacteria (PAO) and denitrifying polyphosphate-accumulating bacteria (DPAO) in the anaerobic tank and the denitrification process in the anoxic section, and ultimately affecting the effectiveness of the satiety-starvation condition, a stirring device is installed in the outlet section of the aerobic tank to mix the sludge and an intermittent aeration program is set. When the intelligent control system receives that the ammonia nitrogen concentration at the outlet of the aerobic zone is higher than 1 mg / L, the outlet section air inlet solenoid valve is opened, otherwise the outlet section air inlet solenoid valve is in a closed state.

[0082] One end of the sedimentation device 140 is on the same side as the other end of the aerobic zone 130 . The sedimentation device 140 includes: a guide plate 141 , a sludge return hopper 142 , a sludge discharge hopper 143 , a sludge sedimentation area 144 and a sludge scraper 145 .

[0083] The guide plate 141 is arranged at the upper middle part of the water inlet end of the sedimentation device 140, that is, between the top and the middle part of the water inlet end.

[0084] Among them, the sludge return hopper 142 is arranged at the bottom of the water inlet end of the sedimentation device 140, the sludge external discharge hopper 143 is arranged at the bottom of the water outlet end of the sedimentation device 140, and the sludge scraper device 145 is arranged in the sludge sedimentation area in the middle of the sedimentation device 140; the guide plate 141 is arranged at 0.5 to 1.0 m from the water inlet end of the sedimentation device 140, with a submersion depth of 0.3 to 0.5 m and 0.1 to 0.15 m above the water surface.

[0085] Specifically, the sludge scraping device can realize two-way sludge scraping. Scraping toward the water inlet end can scrape the sludge with good settling performance to the sludge return hopper, and scraping toward the water outlet end can scrape the sludge with poor settling performance to the sludge discharge hopper, thereby realizing the selective return and elimination of activated sludge.

[0086] Specifically, the water inlet end of the sedimentation device 140 is close to the water inlet end of the anaerobic zone 110 , and the water outlet end of the sedimentation device 140 is close to the water outlet end of the aerobic zone 130 .

[0087] The reflux device includes: a nitrification liquid reflux device and a sludge reflux device. The nitrification liquid reflux device is connected to the water outlet of the aerobic zone 130 and the anaerobic zone 110 and the anoxic zone 120 respectively. The sludge reflux device is connected to the sludge reflux hopper 142 and the water inlet of the anaerobic zone 110 respectively.

[0088] Optionally, the redox potential of the anaerobic zone is maintained at -150 to -225 mV, the dissolved oxygen concentration at the outlet of the aerobic zone is maintained below 0.5 mg / L, and the concentration of the sludge return hopper in the sedimentation tank is maintained above 12000 mg / L.

[0089] Optionally, the system also includes an intelligent control device; the intelligent control device is connected to the stirring device signal, and the intelligent control device is used to control the switch of the stirring device and the stirring rate; the intelligent control device is connected to the reflux pump signal of the reflux device, and the intelligent control device is used to adjust the switch of the reflux pump and the reflux flow rate; the intelligent control device is connected to the microporous aeration device signal, and the intelligent control device is used to control the switch of the microporous aeration device and the aeration flow rate; the intelligent control device is respectively connected to the online monitoring equipment signals of the anaerobic zone, the anoxic zone, the aerobic zone and the sedimentation device.

[0090] Optionally, the outlet section of the aerobic zone is equipped with a microporous aeration device and a stirring device at the same time. The stirring device is turned on for a long time, and the start and stop of the microporous aeration device in the outlet section is regulated according to the signal transmitted by the online monitoring equipment of the aerobic zone.

[0091] Figure 2 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 1 .like Figure 2 As shown, the method is applied to a continuous flow aerobic granular sludge system, the continuous flow aerobic granular sludge system includes a reaction tank, the reaction tank includes a satiation zone and a hunger zone, and the method includes:

[0092] S101. Calculate the real-time influent organic load according to the real-time influent flow rate and the real-time influent chemical oxygen demand concentration of the reaction tank.

[0093] Specifically, the calculation formula of the real-time influent organic load F is:

[0094]

[0095] The unit of F is kgCOD / (m 3 ·d); C is the real-time chemical oxygen demand concentration of the influent, in mg / L; Q is the real-time influent flow rate, in m 3 / d; V is the volume of the reaction tank, in m 3 .

[0096] S102. Calculate the ideal sludge concentration in the saturation zone based on the critical feed-microorganism ratio and the real-time influent organic load.

[0097] Specifically, the calculation formula for the ideal saturated zone sludge concentration M0 under the influent condition is:

[0098]

[0099] The unit of M0 is kgMLSS / m 3 ; A is the critical feed-microorganism ratio, the unit is kgCOD / (kg MLSS·d).

[0100] S103, calculating the ideal sludge return flow rate of the saturated area according to the real-time water inflow rate, the ideal sludge concentration of the saturated area, and the sludge return concentration.

[0101] Specifically, the calculation formula for the ideal sludge return flow V1 in the saturated zone is:

[0102]

[0103] Among them, M1 is the sludge concentration at the bottom of the sludge return hopper, the unit is kgMLSS / m 3 ; The unit of V1 is m 3 ; a1 is the ratio of the primary sludge return concentration to the primary bottom sludge concentration in the primary sludge return hopper.

[0104] Specifically, the empirical value of a1 is generally set at 0.6 to 0.8, and the average value can be calculated after multiple actual sampling tests. This value needs to be adjusted regularly during the granular sludge cultivation process.

[0105] S104 regulates the sludge return flow rate in the saturated zone until the sludge return flow rate is the same as the ideal sludge return flow rate.

[0106] Optionally, the sludge return flow rate of the saturation zone is adjusted regularly until the sludge return flow rate is the same as the ideal sludge return flow rate.

[0107] It should be noted that, after step S104, the following steps are also included:

[0108] Regularly test the real-time satiety-hunger ratio, adjust the real-time satiety-hunger ratio according to the requirements of different granular sludge culture stages, and update the critical food-micro ratio.

[0109] In this embodiment, the change of chemical oxygen demand concentration along the satiety zone is monitored regularly, and the system satiety-starvation ratio is calculated (usually once every half a month, and each time for 3 consecutive days). If the satiety-starvation ratio at this time is less than the lower limit of the set interval, the influent chemical oxygen demand concentration can be increased until the system satiety-starvation ratio returns to the set interval, and the critical feed-micro ratio and the ideal sludge return volume of the satiety zone are recalculated and adjusted according to steps S101 to S104.

[0110] The present embodiment provides a quantitative control method of a satiation-starvation ratio and a continuous flow aerobic granular sludge system, wherein the continuous flow aerobic granular sludge system includes a reaction tank, the reaction tank includes a satiation zone and a starvation zone, and the real-time influent organic load is calculated according to the real-time influent flow rate and the real-time influent chemical oxygen demand concentration of the reaction tank; the ideal sludge concentration of the satiation zone is calculated according to the critical feed-micro ratio and the real-time influent organic load; the ideal sludge return volume of the satiation zone is calculated according to the real-time influent flow rate, the ideal sludge concentration of the satiation zone and the sludge return concentration; and the sludge return volume of the satiation zone is regulated until the sludge return volume is the same as the ideal sludge return volume. Compared with the prior art, certain satiation-starvation conditions are qualitatively created by water inlet mode or sludge return setting, but there are few applied studies on satiation-starvation conditions, and it is impossible to quantitatively calculate and regulate the satiation-starvation ratio, resulting in poor satiation-starvation effect of the system, which in turn affects the granulation efficiency of the continuous flow aerobic granular sludge system. This application is based on the regulation strategy of the critical position of the satiety-hunger ratio, which controls the system's satiety-hunger ratio within a set range, greatly improving the stability of the satiety-hunger environment in the continuous flow system, providing the possibility for the rapid cultivation of AGS in the continuous flow system, and thus improving the efficiency of the continuous flow aerobic granular sludge system.

[0111] Figure 3 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 2 ,exist Figure 2 Based on the example, Figure 3 As shown, the reaction tank includes multiple partitions, including: an anaerobic zone, an anoxic zone and an aerobic zone, and the above S101 also includes:

[0112] S201. Obtain a satiety-hunger ratio critical position according to the total hydraulic retention time and the first satiety-hunger ratio, and divide a plurality of zones into satiety zones and hunger zones according to the satiety-hunger ratio critical position.

[0113] The first satiety-hunger ratio is selected from a preset satiety-hunger ratio range. According to literature reports, the satiety-hunger ratio range of the continuous flow aerobic granular sludge culture system can be set to 0.25-0.5. In the initial stage of startup, the first satiety-hunger ratio can be set to 0.5 for rapid enrichment of microorganisms.

[0114] S202, increasing the chemical oxygen demand concentration of the influent, and obtaining a plurality of parameter values ​​when the sludge return ratio, the sludge concentration in the anaerobic zone, the chemical oxygen demand concentration at the critical position of the satiety-hunger ratio, and the change value of the chemical oxygen demand concentration at the critical position of the satiety-hunger ratio meet their respective preset critical conditions.

[0115] Among them, multiple parameter values ​​include: critical chemical oxygen demand concentration, influent flow rate, activated sludge concentration in the anaerobic zone and reaction tank volume.

[0116] Specific:

[0117] The preset critical conditions include: the sludge return ratio range in the satiety zone, the sludge concentration range in the anaerobic zone, the chemical oxygen demand concentration threshold at the satiety-hunger ratio critical position, and the chemical oxygen demand concentration change threshold at the satiety-hunger ratio critical position.

[0118] The critical position of the satiety-hunger ratio is the terminal chamber of the satiety zone, and the chamber of the hunger zone adjacent to the terminal chamber is the front chamber of the hunger zone.

[0119] The critical position of the satiety-hunger ratio is located at the end of the multiple chambers in the satiety zone, wherein the end of the multiple chambers in the satiety zone is on the same side as the front end of the multiple chambers in the hunger zone.

[0120] S203, calculating the critical food-microbe ratio according to multiple parameter values.

[0121] Specifically, the calculation formula of the critical food-micro ratio A is:

[0122]

[0123] Where F is the real-time influent organic load, in kg COD / m 3 .d; C is the real-time chemical oxygen demand concentration of the influent, in mg / L; Q is the real-time influent flow rate, in m 3 / d; V is the volume of the reaction tank, in m 3 ; The unit of A is kgCOD / (kgMLSS·d); M is the mixed liquor suspended solids concentration (MLSS) in the reaction tank, unit: g / L or kg / m 3 .

[0124] In this embodiment, the critical position of the system's satiety-hunger ratio and the food-micro ratio during the system's satiety period are determined, and regulation is performed based on the critical position of the system's satiety-hunger ratio and the system's satiety period. The system's satiety-hunger ratio is regulated within a set range, which greatly improves the stability of the satiety-hunger environment in the continuous flow system and provides the possibility for the rapid cultivation of AGS in the continuous flow system.

[0125] Figure 4 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 3 ,exist Figure 2 and Figure 3 Based on the example, Figure 4 As shown, each partition is divided into multiple chambers, and the total hydraulic retention time includes: the chamber hydraulic retention time of each chamber, wherein the total hydraulic retention time and the chamber hydraulic retention time are both time periods; then the specific implementation steps of the above S201 include:

[0126] S301. Obtain a hydraulic retention time point corresponding to a first satiety-hunger ratio according to a first satiety-hunger ratio and a total hydraulic retention time.

[0127] S302. The chamber where the hydraulic retention time point is located is used as the critical position of the satiety-hunger ratio.

[0128] For example, the total hydraulic retention time of the biochemical stage of a sewage treatment plant is 12 hours, 2 hours in the anaerobic zone, 3 hours in the anoxic zone, and 7 hours in the aerobic zone. Taking the system satiety-hunger ratio as 0.5, the satiety zone occupies 4 hours.

[0129] The end of the satiety zone is located in the second chamber of the hypoxic zone, and this chamber is set as the critical position of the satiety-hunger ratio.

[0130] In this embodiment, based on the fact that the proportion of the hydraulic retention time of each chamber in the total hydraulic retention time is the same as the proportion of each chamber in the total reaction pool, the hydraulic retention time point corresponding to the first satiety-hunger ratio is calculated through the first satiety-hunger ratio, and then the chamber corresponding to the hydraulic retention time is obtained, and the chamber is used as the critical position of the satiety-hunger ratio. The more chambers are divided, the more accurate the critical position of the satiety-hunger ratio is.

[0131] Figure 5 A schematic diagram of a quantitative control method of satiety-hunger ratio provided in an embodiment of the present application Figure 4 ,exist Figure 2 , Figure 3 and Figure 4 Based on the example, Figure 5 As shown, the specific implementation steps of the above S202 include:

[0132] S401, regulating the sludge return ratio and the sludge concentration until the sludge return ratio meets the sludge return ratio range and the sludge concentration meets the sludge concentration range, and then maintaining the regulated sludge return ratio and sludge concentration.

[0133] For example, the sludge return ratio and the sludge concentration in the anaerobic zone are adjusted until the sludge return ratio is adjusted to 50%-80% and the sludge concentration in the anaerobic zone is maintained at 2-5 g / L.

[0134] S402, gradually increase the chemical oxygen demand concentration of the influent, during which the real-time chemical oxygen demand concentration of the influent, as well as the chemical oxygen demand concentration, influent flow rate and activated sludge concentration of the terminal chamber and the front chamber at each moment are recorded.

[0135] Among them, the chemical oxygen demand concentration of the influent is gradually increased to enrich the functional microorganisms.

[0136] S403. When the chemical oxygen demand concentration of the terminal chamber is less than the chemical oxygen demand concentration threshold, and the chemical oxygen demand concentration change value between the chemical oxygen demand concentration of the terminal chamber and the chemical oxygen demand concentration of the front chamber is less than the chemical oxygen demand concentration change threshold, the real-time influent chemical oxygen demand concentration at the first moment is taken as the critical chemical oxygen demand concentration.

[0137] Among them, the first moment is the moment before the second moment.

[0138] The second moment is the moment when the chemical oxygen demand concentration of the terminal chamber is greater than or equal to the chemical oxygen demand concentration threshold, or when the chemical oxygen demand concentration change value is greater than or equal to the chemical oxygen demand concentration change threshold.

[0139] For example, the COD concentration of the terminal chamber is less than the COD concentration threshold of 50 mg / L; the COD concentration change value between the COD concentration of the terminal chamber and the COD concentration of the front chamber is less than the COD concentration change threshold of 10%.

[0140] In this embodiment, based on the control strategy of the critical position of the satiety-hunger ratio, by real-time monitoring of the chemical oxygen demand concentration of the influent and setting the sludge return flow control strategy in the satiety zone, the critical feed-microorganism ratio of the satiety zone is quantitatively controlled, and the satiety-hunger ratio of the system is controlled within the set range, which greatly improves the stability of the satiety-hunger environment in the continuous flow system and provides the possibility for the rapid cultivation of AGS in the continuous flow system.

[0141] In order to more clearly and completely describe the technical solution of the present invention, the following is further described in detail through specific embodiments. The system used in the embodiments of the present invention is a small-scale continuous flow aerobic granular sludge reactor for treating actual domestic sewage, with a biochemical section volume of 660L and a daily processing scale of 1.32 tons / day. The reactor includes an anaerobic zone, an anoxic zone, an aerobic zone and a sedimentation zone. The total hydraulic retention time of the biochemical section of the system is designed to be 12h, including 2h for the anaerobic tank, 3h for the anoxic tank, and 7h for the aerobic tank. In order to ensure the improvement of the concentration gradient at the inlet end and study the influencing factors and control strategies of satiation-starvation conditions, the anaerobic zone is divided into 27 (9*3) compartments, the residence time of each compartment is about 4.4min, and a baffle of a certain height is provided in each compartment to achieve full mixing of muddy water by surging water inlet; the anoxic zone is divided into 6 compartments, the residence time of each compartment is about 30min, and a stirring device is installed in each compartment.

[0142] In order to ensure the rapid enrichment of functional microorganisms (PAO, DPAO, etc.) in the initial stage, the organic load of the influent should be increased as much as possible, and the first satiety-starvation ratio should be set to 0.5. According to the residence time calculation, the satiety-starvation critical position is located at a residence time of 4h, that is, the fourth compartment of the anoxic zone.

[0143] The actual wastewater inlet COD concentration is 80-120 mg / L, ammonia nitrogen is 20-35 mg / L, and total phosphorus is 1.6-3 mg / L. By supplementing the carbon source, the initial inlet COD average concentration is 200 mg / L, the sludge concentration in the anaerobic zone is 3-5 g / L, and the sludge return ratio is 50%-100%. After starting the device, the COD concentration along the process is tested every week, and the system satiety-starvation ratio is calculated. If the satiety-starvation ratio is greater than 0.5, the sludge return ratio is increased. If the satiety-starvation ratio is less than 0.5, the inlet organic matter concentration is increased until the anoxic zone effluent COD concentration is less than 40 mg / L, and the difference in COD concentration between the anoxic zone effluent and the aerobic zone inlet is less than 6 mg / L.

[0144] The experiment is generally divided into three stages:

[0145] In the first stage (0-50 days), the amount of returned sludge was regulated by the sludge return flow formula to control the sludge concentration at about 4g / L, and the inlet feed-microorganism ratio was gradually increased from 0.1kgCOD / (kgMLSS*d) to 0.2kgCOD / (kgMLSS*d). The system satiety-starvation ratio was calculated according to the COD concentration before and after the critical position. It was found that when the feed-microorganism ratio was about 0.18kgCOD / (kgMLSS*d), the COD concentration at the critical position of the satiety-starvation ratio (anoxic zone chamber 4) was lower than 40mg / L and the COD concentration difference between anoxic zone chamber 4 and anoxic zone chamber 5 was lower than 6mg / L. When the feed-microorganism ratio continued to increase, the above conditions could not be met, indicating that the optimal feed-microorganism ratio was 0.18kgCOD / (kgMLSS*d) under the condition that the critical satiety-starvation ratio was 0.5.

[0146] In the second stage (51-97 days), sludge screening was strengthened when the optimal feeder-microorganism ratio was 0.18kgCOD / (kgMLSS*d). The sedimentation system was adjusted to increase the discharge of sludge with poor sedimentation performance, and the sludge age of the system was controlled to about 5 days. The sludge concentration gradually decreased from 4g / L to about 2g / L. During this process, the sludge concentration was tested every 3 days and the influent COD concentration was adjusted by the optimal feeder-microorganism ratio to maintain the stability of the system and avoid problems such as filamentous bacteria expansion caused by feeder-microorganism ratio shock.

[0147] The third stage (98-125 days) is the stable growth stage of granular sludge. Through the sludge screening and strengthening in the second stage, the sludge with good settling performance is enriched, but the sludge concentration drops significantly. Long-term operation is not conducive to the system's denitrification and phosphorus removal performance. At this time, it is necessary to gradually increase the influent organic load and reduce sludge discharge, and increase the sludge return volume to increase the sludge concentration. On the other hand, while increasing the influent organic load, attention should be paid to the regulation of the food-micro ratio. At this stage, functional microorganisms have been enriched, and more attention should be paid to the large-scale reproduction of heterotrophic microorganisms and the expansion of filamentous bacteria caused by the high satiation-hunger ratio. Therefore, during this process, COD concentration along the process was regularly tested, the actual satiation-hunger ratio of the system was calculated, and the actual satiation-hunger ratio of the system was adjusted to 0.3 in combination with the sludge settling performance. At the same time, the optimal food-micro ratio was adjusted according to the first stage method, and the system food-micro ratio was gradually reduced to about 0.15kgCOD / (kgMLSS*d), and the sludge concentration gradually increased from 2.08mg / L to 4.25mg / L.

[0148] Through the above method, after 4 months of operation, the system has formed obvious granular sludge. Under experimental conditions, the average particle size of the activated sludge increased from 52um in the initial stage to 230um.

[0149] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments, and the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for quantitatively controlling satiety-hunger ratio, characterized in that: The method is applied to a continuous flow aerobic granular sludge system, wherein the continuous flow aerobic granular sludge system comprises a reaction tank, wherein the reaction tank comprises a satiation zone and a hunger zone, and the method comprises: Calculating the real-time influent organic load according to the real-time influent flow rate and the real-time influent chemical oxygen demand concentration of the reaction tank; The ideal sludge concentration in the saturation zone is calculated based on the critical feed-microorganism ratio and the real-time influent organic load; According to the real-time water inflow rate, the ideal sludge concentration and the sludge return concentration of the saturated zone, the ideal sludge return rate of the saturated zone is calculated; The sludge return flow rate of the saturation zone is regulated until the sludge return flow rate is the same as the ideal sludge return flow rate.

2. The method according to claim 1, characterized in that The reaction tank comprises a plurality of partitions, wherein the plurality of partitions comprises: an anaerobic zone, an anoxic zone and an aerobic zone; Before calculating the real-time influent organic load according to the real-time influent flow rate and the real-time influent chemical oxygen demand concentration of the reaction tank, the method further comprises: According to the total hydraulic retention time and the first satiety-hunger ratio, a satiety-hunger ratio critical position is obtained, and according to the satiety-hunger ratio critical position, the plurality of subareas are divided into the satiety area and the hunger area; wherein the first satiety-hunger ratio is selected from a preset satiety-hunger ratio interval; Increasing the chemical oxygen demand concentration of the influent, and obtaining a plurality of parameter values ​​when the sludge return ratio of the saturated zone, the sludge concentration of the anaerobic zone, the chemical oxygen demand concentration at the critical position of the saturated-starved ratio, and the change value of the chemical oxygen demand concentration at the critical position of the saturated-starved ratio meet respective preset critical conditions; wherein the plurality of parameter values ​​include: critical chemical oxygen demand concentration, influent flow rate, activated sludge concentration of the anaerobic zone, and reaction tank volume of the saturated zone; The critical food-microorganism ratio is calculated according to the multiple parameter values.

3. The method according to claim 2, characterized in that Each of the partitions is equally divided into a plurality of chambers, and the total hydraulic retention time includes: a chamber hydraulic retention time of each of the chambers, wherein the total hydraulic retention time and the chamber hydraulic retention time are both time periods; The step of obtaining the critical position of the satiety-hunger ratio according to the total hydraulic retention time and the first satiety-hunger ratio comprises: According to the first satiety-hunger ratio and the total hydraulic retention time, obtaining a hydraulic retention time point corresponding to the first satiety-hunger ratio; The chamber where the hydraulic retention time point is located is taken as the critical position of the satiety-hunger ratio.

4. The method according to claim 3, characterized in that The preset critical conditions include: the sludge return ratio range of the satiety zone, the sludge concentration range of the anaerobic zone, the chemical oxygen demand concentration threshold of the satiety-hunger ratio critical position, and the chemical oxygen demand concentration change threshold of the satiety-hunger ratio critical position; The critical position of the satiety-hunger ratio is the terminal chamber of the satiety zone, and the chamber of the hunger zone adjacent to the terminal chamber is the front chamber of the hunger zone; The satiety-hunger ratio critical position is located at the end of the multiple chambers in the satiety zone, wherein the end of the multiple chambers in the satiety zone is on the same side as the front end of the multiple chambers in the hunger zone.

5. The method according to claim 4, characterized in that When the sludge return ratio of the satiety zone, the sludge concentration of the anaerobic zone, the chemical oxygen demand concentration at the satiety-hunger ratio critical position, and the chemical oxygen demand concentration change value at the satiety-hunger ratio critical position meet their respective preset critical conditions, multiple parameter values ​​are obtained, including: Regulating the sludge return ratio and the sludge concentration until the sludge concentration satisfies the sludge concentration range, and then maintaining the regulated sludge return ratio and sludge concentration; Gradually increasing the chemical oxygen demand concentration of the influent, during which the real-time chemical oxygen demand concentration of the influent, as well as the chemical oxygen demand concentrations of the terminal chamber and the front chamber, the influent flow rate and the activated sludge concentration at each moment are recorded; When the chemical oxygen demand concentration of the terminal chamber is less than the chemical oxygen demand concentration threshold, and the chemical oxygen demand concentration change value between the chemical oxygen demand concentration of the terminal chamber and the chemical oxygen demand concentration of the front chamber is less than the chemical oxygen demand concentration change threshold, the real-time influent chemical oxygen demand concentration at the first moment is used as the critical chemical oxygen demand concentration; wherein the first moment is the moment before the second moment; and the second moment is the moment when the chemical oxygen demand concentration of the terminal chamber is greater than or equal to the chemical oxygen demand concentration threshold, or the chemical oxygen demand concentration change value is greater than or equal to the chemical oxygen demand concentration change threshold.

6. The method according to claim 5, characterized in that After regulating the sludge return amount of the saturated zone until the sludge return amount is the same as the ideal sludge return amount, the method further comprises: Regularly test the real-time satiety-hunger ratio, adjust the real-time satiety-hunger ratio according to the requirements of different granular sludge culture stages, and update the critical food-micro ratio.

7. A continuous flow aerobic granular sludge system, characterized in that: The system comprises: a reaction tank; The reaction pool includes a plurality of partitions, and the plurality of partitions are divided into a satiation zone and a hunger zone; The multiple partitions include: an anaerobic zone, an anoxic zone, and an aerobic zone; One end of the anaerobic zone is on the same side as the other end of the anoxic zone, and one end of the aerobic zone is on the same side as the other end of the anaerobic zone and the other end of the anoxic zone.

8. The system according to claim 7, characterized in that The anaerobic zone and the anoxic zone both include: a plurality of chambers, partition walls, water holes and a stirring device; each of the chambers is obtained by evenly dividing the anaerobic zone or the anoxic zone by the partition walls, each of the partition walls is provided with a water hole, and the liquids between two adjacent chambers are connected through the water holes; each of the chambers of the anaerobic zone and the anoxic zone is provided with a stirring device; The aerobic zone is connected to the anaerobic zone and the anoxic zone respectively through the water holes. The aerobic zone includes: a plurality of aerobic tanks, baffles, microporous aeration devices and stirring devices; each aerobic tank is obtained by evenly dividing the aerobic zone by the baffles.

9. The system according to claim 8, characterized in that The system also includes: a precipitation device and a reflux device; One end of the sedimentation device is on the same side as the other end of the aerobic zone, and the sedimentation device comprises: a guide plate, a sludge return hopper, a sludge external discharge hopper, a sludge sedimentation area and a sludge scraping device; the guide plate is arranged between the top and the middle of the water inlet end of the sedimentation device, the sludge return hopper is arranged at the bottom of the water inlet end of the sedimentation device, the sludge external discharge hopper is arranged at the bottom of the water outlet end of the sedimentation device, and the sludge scraping device is arranged in the sludge sedimentation area in the middle of the sedimentation device; The reflux device comprises a nitrification liquid reflux device and a sludge reflux device. The nitrification liquid reflux device is respectively connected to the water outlet of the aerobic zone and the anaerobic zone and the anoxic zone. The sludge reflux device is respectively connected to the sludge reflux hopper and the water inlet of the anaerobic zone.

10. The system according to claim 9, characterized in that The dissolved oxygen concentration in the anaerobic zone should be maintained below 0.05 mg / L, the redox potential in the anaerobic zone should be maintained at -150 to -225 mV, the dissolved oxygen concentration at the outlet of the aerobic zone should be maintained below 0.5 mg / L, and the concentration in the sludge return hopper of the sedimentation tank should be maintained above 12,000 mg / L.

11. The system according to claim 9, characterized in that The system also includes an intelligent control device; The intelligent control device is connected to the stirring device by signal, and the intelligent control device is used to control the switch and stirring rate of the stirring device; The intelligent control device is connected to the reflux pump signal of the reflux device, and the intelligent control device is used to adjust the switch of the reflux pump and the reflux flow rate; The intelligent control device is connected to the microporous aeration device by signal, and the intelligent control device is used to control the switch and aeration flow of the microporous aeration device; The intelligent control device is respectively connected to the online monitoring devices of the anaerobic zone, the anoxic zone, the aerobic zone and the precipitation device by signals.

12. The system according to claim 11, characterized in that The outlet water section of the aerobic zone is equipped with a microporous aeration device and a stirring device. The stirring device is turned on for a long time, and the start and stop of the microporous aeration device of the outlet water section is regulated according to the signal transmitted by the online monitoring equipment of the aerobic zone.

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