Device and method for realizing synchronous nitrification and denitrification based on time and space control

Abstract

The invention discloses a device and a method for realizing synchronous nitrification and denitrification based on time and space control, a sequencing batch reactor in the device is internally provided with a stirring paddle and an aeration ring, the stirring paddle is provided with a plurality of stirring blades, the form of the stirring blades is set according to space flow state control requirements, and then different sludge concentration partitions are controlled to be formed; the aeration ring is arranged in the middle of the reactor and is connected with an air compressor through an air supply pipe, and a gas flow meter is arranged on the air supply pipe; a bottom interface of the sequencing batch reactor is sequentially connected with a peristaltic pump and a sewage tank through a pipeline; the reactor is further provided with a DO sensor and a pH sensor which are used for detecting the dissolved oxygen content and the pH value in real time; the process controller is electrically connected with the DO sensor, the pH sensor and the gas flow meter respectively, and synchronous nitrification and denitrification in the system are realized through integrated time sequence and spatial distribution coordinated regulation, so that the purposes of effectively improving the sewage treatment efficiency and deeply removing nitrogen and phosphorus are achieved.

Description

Technical Field

[0001] This invention relates to the field of biological wastewater treatment, and in particular to a device and method for achieving simultaneous nitrification and denitrification based on time and space control. Specifically, it achieves simultaneous nitrification and denitrification within the system through coordinated regulation of time and space, thereby improving wastewater treatment efficiency and achieving deep nitrogen and phosphorus removal. Background Technology

[0002] Traditional biological nitrogen and phosphorus removal processes primarily utilize the metabolic characteristics of microorganisms under aerobic and anoxic conditions to complete nitrification, denitrification, phosphorus release, phosphorus uptake, and organic matter removal, thereby achieving efficient pollutant degradation. Therefore, based on different reactor types, traditional nitrogen and phosphorus removal processes can generally be divided into continuous flow reactors and sequencing batch reactors (SBRs). Continuous flow reactors spatially divide the environment into anaerobic, anoxic, and aerobic zones. Wastewater and microorganisms flow sequentially through these zones in a plug flow manner, achieving the corresponding pollutant removal process within each zone. Sequencing batch reactors, on the other hand, control the on / off of aeration over time, creating anaerobic, anoxic, and aerobic conditions within a single reaction zone, allowing microorganisms to remove pollutants at different times. However, traditional biological treatment processes also suffer from problems such as long process flows, complex equipment, and high operational control difficulty. Bottom aeration requires overcoming the water depth pressure of the entire tank, resulting in limited mass transfer efficiency and high aeration energy consumption.

[0003] To simplify operation and reduce energy consumption, simultaneous nitrification-denitrification (SND) technology creates both aerobic and anoxic microenvironments in the same reactor and within the same timeframe, allowing nitrifying and denitrifying bacteria to coexist. This enables ammonia oxidation and nitrate reduction to occur simultaneously, significantly shortening the overall wastewater treatment process and reaction time. The key to SND lies in controlling the dissolved oxygen gradient within the reaction system or constructing different zones while ensuring effective mass transfer. Currently, commonly used methods include intermittent aeration, granular sludge, packing materials, and carriers. However, these methods largely rely on controlling operating parameters or variations in sludge characteristics, resulting in poor spatial controllability and insufficient stability, making it difficult to maintain ideal, stable operation over the long term. Summary of the Invention

[0004] In view of the above problems, the present invention provides a device for achieving simultaneous nitrification and denitrification based on time and space control to overcome or at least partially solve the above problems. It achieves different sludge concentration control in different zones by optimizing flow control, achieves spatial anoxic / aerobic zone control based on the different dissolved oxygen (DO) requirements of microorganisms, and establishes different vertical DO distribution gradients through the aeration ring in the middle, further reducing aeration pressure and aeration energy consumption.

[0005] According to one aspect of the present invention, an apparatus for achieving simultaneous nitrification and denitrification based on time and space control is provided, comprising a sequencing batch reactor, a DO sensor, a pH sensor, a gas flow meter, a stirring paddle, an aeration ring, a wastewater tank, a peristaltic pump, an air compressor, and a process controller;

[0006] The sequencing batch reactor is equipped with an agitator and an aeration ring. The agitator has multiple agitator blades, and the shape of the blades is set according to the spatial flow control requirements to control different sludge concentration zones. The aeration ring is arranged in the middle of the sequencing batch reactor to reduce the aeration water pressure and form a dissolved oxygen concentration gradient in conjunction with spatial control, thus creating an aerobic environment in the upper layer, a low-oxygen environment in the middle layer, and an anoxic environment at the bottom.

[0007] The aeration ring is connected to the air compressor via an air supply pipe, and a gas flow meter is installed on the air supply pipe.

[0008] The bottom interface of the sequencing batch reactor is connected to a peristaltic pump and a wastewater tank in sequence via pipelines;

[0009] The DO sensor is used to detect the dissolved oxygen content in the sequencing batch reactor, and the pH sensor is used to detect the pH value in the sequencing batch reactor.

[0010] The process controller is electrically connected to the DO sensor, pH sensor and gas flow meter respectively.

[0011] Optionally, the aeration ring is made of porous stone material, and the interior of the aeration ring has a dual-scale pore structure, including main micropores and surface hierarchical fine pores, and the surface is coated with a micro-textured layer coating.

[0012] Optionally, the porous stone material is sintered ceramic, sintered quartz sand, or activated corundum sand; the value range of the main micropores is 10-50 μm; the value range of the surface layer micropores is 1-10 μm; and the value range of the roughness of the microtextured coating layer is 1-10 μm.

[0013] Optionally, multiple stirring blades are installed sequentially from the bottom to the top of the stirring paddle, with their lengths increasing sequentially, and the position of each stirring blade is adjustable.

[0014] Optionally, the number of stirring blades is three, and the length ratio of each stirring blade from bottom to top is 1:2:2.5. By utilizing the different hydraulic disturbance amplitudes of the different lengths of the stirring blades at the same rotation speed, a flow field stratification is formed. Based on the flow state control, the activated sludge in the sequencing batch reactor forms a high sludge concentration zone and a low sludge concentration zone. The high sludge concentration zone forms an anoxic zone under the aerobic action of microorganisms, while the low sludge concentration zone maintains normal DO concentration, heterotrophic activity, and nitrification.

[0015] An agitator is provided on the top of the stirring paddle, and the agitator is electrically connected to the process controller.

[0016] Optionally, the aeration ring is a closed-loop structure, installed at 0.4-0.6 times the effective liquid depth of the sequencing batch reactor, with a maximum diameter of about 0.9 times the diameter of the sequencing batch reactor, a ring width ranging from 1.5-2 cm, and a thickness ranging from 1-1.5 cm.

[0017] Optionally, the sequencing batch reactor is provided with an outlet port in the middle or at the bottom, and an outlet valve is provided on the outlet port, the outlet valve being electrically connected to the process controller.

[0018] According to another aspect of the present invention, a method for operating an apparatus for achieving simultaneous nitrification and denitrification based on time and space control according to any one of the preceding claims is provided, comprising the following steps:

[0019] Step 1: Introduce water into the sequencing batch reactor;

[0020] Step 2: Start the agitator to perform anaerobic mixing. Polysaccharitrophs fully absorb and store the carbon source in the wastewater, converting it into an internal carbon source, while polyphosphate-accumulating bacteria release phosphorus.

[0021] Step 3: Start the air compressor to carry out the aerobic reaction. Nitrifying bacteria and polyphosphate-accumulating bacteria convert ammonia nitrogen into nitrate nitrogen or nitrite nitrogen in the aerobic zone at the top of the sequencing batch reactor. Polyphosphate-accumulating bacteria store phosphorus in their bodies by absorbing phosphorus. The high sludge concentration zone at the bottom of the sequencing batch reactor forms an anoxic zone due to the aerobic respiration of cells. Denitrification is carried out by making full use of carbon sources, and simultaneous denitrification converts oxidized nitrogen into nitrogen gas.

[0022] Step 4: Start the agitator to perform anaerobic stirring, and use the internal carbon source stored in the polysaccharide bacteria to further remove the remaining nitrate or nitrite nitrogen.

[0023] Step 5: Drain the water after sedimentation.

[0024] Optionally, in step two, the dissolved oxygen concentration in the low sludge concentration zone at the top of the sequencing batch reactor is controlled within a preset range by using a DO sensor.

[0025] In step three, aeration is stopped promptly when the pH value changes from decreasing to increasing, as monitored by the pH sensor.

[0026] Optionally, in step two, by utilizing the different hydraulic disturbance amplitudes of different lengths of the stirring blades at the same rotation speed, a flow field stratification is formed, and based on the flow state control, a high sludge concentration zone and a low sludge concentration zone are formed in the activated sludge in the sequencing batch reactor; the high sludge concentration zone forms an anoxic zone under the aerobic action of microorganisms, while the low sludge concentration zone maintains normal DO concentration, heterotrophic action and nitrification.

[0027] In step three, the aeration water pressure is reduced in the sequencing batch reactor by using an aeration ring, and a dissolved oxygen concentration gradient is formed by combining spatial control, resulting in a state of aerobic upper layer, low oxygen middle layer and anoxic bottom layer.

[0028] The beneficial effects of this invention are:

[0029] According to the technical solution provided by this invention, the flow pattern within the reactor is precisely controlled through an innovative design of the stirring paddle blade shape, thereby achieving zoned distribution of sludge concentration. Simultaneously, the traditional aeration method is optimized by adopting an improved annular aeration ring positioned in the center of the reactor. This improves aeration efficiency, forms a uniform microbubble zone, effectively reduces aeration pressure, and constructs a vertical dissolved oxygen concentration gradient. This dissolved oxygen gradient, combined with the differences in dissolved oxygen consumption among different sludge concentration zones, creates distinct aerobic and anoxic functional zones within the system, thus achieving simultaneous nitrification and denitrification within the aerobic section. Furthermore, leveraging the inherent advantage of sequencing batch reactors (SBRs) in achieving anaerobic-aerobic-anoxic conditions over time, the AOA (Automatic Aeration) operating mode fully utilizes the carbon source in the raw water. By combining the advantages of both, multi-stage removal of carbon, nitrogen, and phosphorus is achieved through coordinated temporal and spatial control, thereby improving wastewater treatment efficiency and enhancing deep nitrogen and phosphorus removal. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a device for achieving simultaneous nitrification and denitrification based on space and time control in one embodiment of the present invention;

[0031] In the diagram: 1-PLC controller (process controller); 2-Agitator; 3-Sequencing batch reactor; 4-Outlet valve; 5-DO sensor; 6-pH sensor; 7-Gas flow meter; 8-Agitator; 9-Annular aeration ring; 10-Sewage tank; 11-Peristaltic pump; 12-Air compressor;

[0032] Figure 2 This is a schematic diagram of the aeration ring structure in one embodiment of the present invention;

[0033] Figure 3 This is a reactor operation sequence diagram in one embodiment of the present invention;

[0034] Figure 4 This is a velocity distribution cloud map of a gas-liquid mixture simulated by analysis simulation software (Ansys Fluent) in one embodiment of the present invention;

[0035] Figure 5 This is a phase volume fraction distribution cloud map simulated by analysis simulation software (Ansys Fluent) in one embodiment of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] like Figure 1 As shown, the simultaneous nitrification and denitrification device of the present invention includes a PLC process controller, a stirrer, a sequencing batch reactor (SBR), an outlet valve, a DO sensor (controller), a pH sensor (controller), a gas flow meter, a stirring paddle, a ring aeration ring, a wastewater tank, a peristaltic pump, and an air compressor. The domestic wastewater tank has a volume of 200L, and the effective volume of the biological aeration filter reactor is 10L. The SBR is made of plexiglass, and the inlet tank is made of organic plastic.

[0038] The sequencing batch reactor 3 is connected to the wastewater tank 10 via a peristaltic pump 11. Inside the sequencing batch reactor 3, there is a stirrer 2, an aeration ring 9, a DO sensor 5, and a pH sensor 6. The stirrer 2 is connected to a stirring paddle 8 with a special blade structure. The aeration ring is connected to the inside of the reactor via a fixed bracket. The aeration rate of the ring aeration ring 9 is controlled by a gas flow meter 7. The gas flow meter 7 is connected to an air compressor 12 to provide aeration for the system. All devices are centrally controlled by a PLC controller 1.

[0039] In terms of time control, the advantages of the sequencing batch time control of the SBR reactor are fully utilized. The stirring and aeration are controlled by PLC to achieve the sequencing batch anaerobic-aerobic-anoxic conditions.

[0040] In terms of spatial control, the sludge concentration in different areas of the reactor is altered by adjusting the blade length at different positions of the agitator, creating zones with varying sludge concentrations. Combined with modified aeration rings, aeration efficiency is further improved. These rings, installed in the middle of the system, provide a uniformly distributed microbubble zone and reduce aeration pressure. Simultaneously, different vertical DO distribution gradients are constructed. By considering the varying dissolved oxygen consumption levels in different sludge concentration zones, aerobic and anoxic zones are achieved within the system, enabling simultaneous nitrification and denitrification in the aerobic stage. Leveraging the inherent advantages of sequencing batch reactors (SBRs) in achieving anaerobic-aerobic-anoxic processes over time, the AOA (Automatic Aeration) operating mode fully utilizes the carbon source in the raw water, achieving multi-stage removal of carbon, nitrogen, and phosphorus over time, thereby improving wastewater treatment efficiency and achieving deep nitrogen and phosphorus removal.

[0041] The municipal sewage used in the specific implementation experiment was taken from a septic tank at a base in Daxing District, Beijing. The chemical oxygen demand (COD) was 180-220 mg / L, and the NH4+ was... + The -N concentration is 50-80 mg / L, and the P concentration is 4-10 mg / L, which is typical of domestic sewage with a low carbon-to-nitrogen ratio and a low carbon-to-phosphorus ratio.

[0042] The specific implementation process is as follows:

[0043] Spatial control of flow pattern within a sequencing batch reactor (SBR): The lengths of the agitator blades within the reactor are set in a 1:2:2.5 ratio from bottom to top (effective liquid level depth). In this reactor, the blade lengths are 1cm, 2cm, and 2.5cm from top to bottom. The different hydraulic disturbance amplitudes at the same rotational speed due to different blade lengths create flow field stratification. Furthermore, the activated sludge within the reactor will form high-sludge concentration zones and low-sludge concentration zones (e.g., ...). Figure 4 (As shown). High sludge concentration zones will form anoxic zones under the aerobic action of microorganisms, while low sludge concentration zones will maintain normal DO concentrations, thus maintaining normal heterotrophic and nitrification processes.

[0044] The aeration device inside the reactor differs from traditional bottom aeration devices; it employs a central annular aeration ring (9) based on the actual reactor dimensions. Figure 2 As shown. The main body of the ring-type aeration ring is made of porous stone material, including sintered ceramics, sintered quartz sand, and corundum sand. In this embodiment, the aeration ring is made of sintered ceramic. The aeration ring has a dual-scale pore structure inside, with micropores (50μm) in the main body and a gradient structure of fine pores (10μm) on the surface, coated with a micro-textured layer (roughness Ra = 10μm). The dual-scale pore structure allows bubbles to split twice during the generation stage to form small and uniform bubble groups, improving oxygen mass transfer efficiency. The surface micro-textured layer can reduce the attachment time of bubbles near cavities, further promoting continuous and stable bubble release. The aeration ring is a closed ring structure, preferably installed at the middle position (0.5 times) of the effective liquid depth of the reactor to reduce the aeration pressure caused by the water depth. The diameter is 0.9 times that of the reactor, the ring width is 2cm, and the thickness is 1.5cm. The aeration ring is connected to the inside of the reactor through a fixed bracket, and the gas is connected to the gas flow meter 7 and the air compressor 12 through the gas supply pipe.

[0045] Time control within the sequencing batch reactor (SBR): The advantages of the SBR's sequencing batch time control are fully utilized. PLC control of stirring and aeration is used to achieve the anaerobic-aerobic-anoxic conditions of the sequencing batch reactor. The operation mode in this embodiment is as follows: Figure 3 As shown, the influent time is 10 minutes, anaerobic stirring is 1 hour, aerobic stirring is 1.5 hours, anaerobic stirring is 1 hour, sedimentation is 15 minutes, and drainage is 5 minutes. This cycle is repeated 2-3 times daily. In the anaerobic section, polysaccharide-producing bacteria fully absorb and store the carbon source from the raw water as an internal carbon source, while polyphosphate-accumulating bacteria release phosphorus. In the aerobic section, dissolved oxygen in the upper low sludge concentration zone is controlled at 1.5-2 mg / L by DO sensor 5, and aeration is stopped promptly by monitoring the ammonia trough point (the inflection point where the pH value in the aeration section changes from decreasing to increasing) by pH sensor 6. Nitrifying bacteria and polyphosphate-accumulating bacteria convert ammonia nitrogen to nitrate nitrogen / nitrite nitrogen in the upper aerobic zone. Polyphosphate-accumulating bacteria store phosphorus in their bodies through phosphorus uptake. The bottom high sludge concentration zone forms an anoxic zone due to aerobic respiration of cells. Figure 5As shown in the diagram, the system fully utilizes the carbon source within the system for denitrification, achieving simultaneous denitrification in the aerobic zone to convert oxidized nitrogen into nitrogen gas. A short anoxic zone is then introduced, utilizing the intracellular carbon source to further remove the remaining nitrate / nitrite nitrogen. Through time and space control, simultaneous nitrification and denitrification are achieved, further realizing deep nitrogen and phosphorus removal from the system.

[0046] Experimental results show that the COD removal rate in domestic sewage reaches over 78%, the ammonia nitrogen removal rate reaches over 98%, and the total nitrogen removal rate reaches over 95%. Through time and space control, a good anaerobic / anoxic zone was achieved within the system. A good dissolved oxygen concentration gradient was established around the central aeration ring: aerobic at the top (DO = 2.5 mg / L), hypoxic in the middle (DO = 0.5 mg / L), and anoxic at the bottom (DO ≤ 0.1 mg / L), significantly reducing aeration energy consumption. The system achieved an 80% nitrogen removal rate within 1.5 hours of aerobic operation. The entire system, through the synergistic effect of time and space control, significantly improves the removal efficiency of carbon, nitrogen, and phosphorus, reduces energy consumption, and can further cope with the impact of different hydraulic loads through time control, improving the system's stability and shock resistance, demonstrating significant engineering practical value.

[0047] The apparatus and method for achieving simultaneous nitrification and denitrification based on time and space control in this invention have been described in detail above. Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in specific implementation methods and applications based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A device for achieving simultaneous nitrification and denitrification based on time and space control, characterized in that, The device comprises a sequencing batch reactor, a DO sensor, a pH sensor, a gas flow meter, a stirring paddle, an aeration ring, a sewage tank, a peristaltic pump, an air compressor and a process controller. The sequencing batch reactor is internally provided with a stirring paddle and an aeration ring, the stirring paddle is provided with a plurality of stirring blades, the stirring blade form is set according to the space flow state control requirement, thereby controlling different sludge concentration partitions, and the aeration ring is arranged in the middle of the sequencing batch reactor to reduce the aeration water pressure, and cooperates with the space control to form a dissolved oxygen concentration gradient, thereby constructing an upper layer aerobic environment, a middle layer low oxygen environment and a bottom layer anoxic environment. The aeration ring is connected with the air compressor through a gas supply pipe, and the gas supply pipe is provided with a gas flow meter. The bottom interface of the sequencing batch reactor is connected with the peristaltic pump and the sewage tank through pipelines in sequence. The DO sensor is used for detecting the dissolved oxygen content in the sequencing batch reactor, and the pH sensor is used for detecting the pH value in the sequencing batch reactor. The process controller is electrically connected with the DO sensor, the pH sensor and the gas flow meter.

2. The device for controlling simultaneous nitrification and denitrification based on time and space according to claim 1, characterized in that, The aeration ring is made of porous stone material, the inside of the aeration ring is a double-scale pore structure, including main micropores and surface secondary fine pores, and the surface is coated with a micro-text layer coating.

3. The device for controlling simultaneous nitrification and denitrification based on time and space according to claim 2, characterized in that, The porous stone material is sintered ceramic, sintered quartz sand or active corundum sand, the main micropores have a value range of 10-50 μm, the surface secondary fine pores have a value range of 1-10 μm, and the micro-text layer coating has a roughness value range of 1-10 μm.

4. The device for controlling simultaneous nitrification and denitrification based on time and space according to any one of claims 1-3, characterized in that, A plurality of stirring blades are installed in the bottom to the top of the stirring paddle in sequence, and the lengths increase in sequence, and the positions of the stirring blades are adjustable.

5. The device for controlling simultaneous nitrification and denitrification based on time and space according to claim 4, characterized in that, The number of the stirring blades is three, the length ratio of the stirring blades from the bottom to the top is 1:2:2.5, the different lengths of the stirring blades are used to form flow field stratification based on the different hydraulic disturbance amplitudes under the same rotating speed, and the active sludge in the sequencing batch reactor is controlled to form a high sludge concentration area and a low sludge concentration area. The high sludge concentration area forms an anoxic area under the aerobic action of microorganisms, and the low sludge concentration area maintains normal DO concentration, heterotrophic action and nitrification. The top of the stirring paddle is provided with a stirrer, and the stirrer is electrically connected with the process controller.

6. The device for controlling simultaneous nitrification and denitrification based on time and space according to any one of claims 1-3, characterized in that, The aeration ring has a closed ring structure, is installed at 0.4-0.6 times of the effective liquid depth of the sequencing batch reactor, has a maximum diameter of about 0.9 times of the diameter of the sequencing batch reactor, has a ring belt width value range of 1.5-2 cm, and has a thickness value range of 1-1.5 cm.

7. The device for controlling simultaneous nitrification and denitrification based on time and space according to any one of claims 1-3, characterized in that, The middle or bottom of the sequencing batch reactor is provided with a water outlet interface, the water outlet interface is provided with a water outlet valve, and the water outlet valve is electrically connected with the process controller.

8. The method of operating a device for controlling simultaneous nitrification and denitrification based on time and space according to any one of claims 1-7, characterized in that, The method comprises the following steps: Step one, feeding water into the sequencing batch reactor; Step two, starting the stirring paddle to perform anaerobic stirring, so that the glycogen bacteria can fully absorb the carbon source in the sewage and store and convert it into internal carbon source, and the phosphorus accumulating bacteria can perform phosphorus release process; Step three, start the air compressor, and carry out aerobic reaction. Nitrifying bacteria and phosphorus accumulating bacteria in the upper aerobic zone of the sequencing batch reactor convert ammonia nitrogen into nitrate nitrogen or nitrite nitrogen. Phosphorus accumulating bacteria store phosphorus in the body by absorbing phosphorus. The high sludge concentration zone at the bottom of the sequencing batch reactor forms an anoxic zone due to aerobic respiration of cells, fully utilizes carbon source for denitrification, and realizes simultaneous denitrification to convert oxidized nitrogen into nitrogen gas. Step four, start the stirring paddle, and carry out anaerobic stirring. The remaining nitrate nitrogen or nitrite nitrogen is further removed by using the internal carbon source stored in the glycogen bacteria. Step five, drain the water after precipitation.

9. The method of claim 8, wherein, In step two, the DO sensor is used to control the concentration of dissolved oxygen in the low sludge concentration zone of the sequencing batch reactor within a preset range. In step three, the pH sensor is used to monitor the inflection point when the pH value changes from decreasing to increasing, and the aeration is stopped in time.

10. The method according to claim 8 or 9, characterized in that, In step two, the different lengths of the stirring paddle blades are used to form a layered flow field under the same rotational speed, and the flow state is used to control the formation of high and low sludge concentration zones in the activated sludge in the sequencing batch reactor. The high sludge concentration zone forms an anoxic zone under the aerobic action of microorganisms, while the low sludge concentration zone maintains normal DO concentration, heterotrophic action, and nitrification. In step three, the aeration ring is used to reduce the aeration water pressure in the sequencing batch reactor, and the space is controlled to form a dissolved oxygen concentration gradient, forming an upper aerobic zone, a middle low oxygen zone, and a bottom anoxic zone.

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