Device and method for realizing autotrophic and heterotrophic coupled deep nitrogen and phosphorus removal of sewage with low carbon nitrogen ratio based on continuous flow membrane aeration bio-membrane reactor

Abstract

The invention discloses a device and a method for realizing low-carbon-nitrogen-ratio sewage autotrophic and heterotrophic coupled deep nitrogen and phosphorus removal based on a continuous flow membrane aeration bio-membrane reactor. A hollow fiber membrane is arranged in the continuous flow reactor, and an oxygen concentration gradient is formed through a bubble-free membrane aeration technology. In the biomembrane area, spatial partitions of functional bacteria such as nitrifying bacteria and anaerobic ammonium oxidation bacteria are established, and the two anoxic areas realize efficient nitrogen removal through short-cut denitrification coupling anaerobic ammonium oxidation (PD / A) and synchronous nitrification and denitrification. In the aspect of phosphorus removal, the system adopts an anaerobic-aerobic operation mode, phosphorus-accumulating bacteria release phosphorus anaerobically and absorb excessive phosphorus aerobically, and finally, phosphorus removal is realized through residual sludge discharge. The system integrates an internal carbon source extraction process, recovers a sludge carbon source and supplements an electron donor required by denitrification, and reduces the operation cost and carbon emission. The continuous flow MABR denitrification system enhances the denitrification efficiency of the PD / A system, is suitable for large-scale operation, and efficiently and stably realizes deep denitrification of a low-carbon-nitrogen-ratio urban sewage treatment plant.

Description

Technical Field

[0001] The invention relates to a process technology for realizing deep denitrification and phosphorus removal by autotrophic and heterotrophic coupling of low carbon-nitrogen ratio sewage based on a continuous flow membrane aeration biofilm reactor, belonging to the field of sewage biological treatment. Background Art

[0002] With the acceleration of urbanization, urban sewage treatment faces the dual challenges of meeting emission standards and saving energy and reducing consumption. In recent years, although organic pollution has been controlled to a certain extent, the excessive discharge of nutrients such as nitrogen and phosphorus has led to increasingly serious eutrophication of water bodies. Denitrification and phosphorus removal have become a major demand for water pollution control. However, urban sewage in my country generally has a low carbon-nitrogen ratio. Traditional denitrification processes require a large amount of aeration energy and external organic carbon sources, and are accompanied by secondary pollution problems such as large amounts of residual sludge treatment and greenhouse gas emissions. Therefore, the development of low-carbon and high-efficiency deep denitrification technologies has become an urgent need in the current sewage treatment field.

[0003] The PD / A process is an innovative two-step biological denitrification technology. It reduces nitrate to nitrite through short-term nitrification under anoxic conditions, and then directly converts nitrite and ammonia nitrogen into nitrogen gas through anaerobic ammonia oxidation. This process breaks through the limitations of traditional nitrification and denitrification. In theory, it does not require an external carbon source and aeration. It has the advantages of low energy consumption and low sludge production. It is particularly suitable for low C / N wastewater treatment. However, there are still technical bottlenecks in practical applications: the carbon source needs to be precisely controlled to maintain nitrite accumulation, but this may lead to additional consumption of the carbon source; fluctuations in parameters such as dissolved oxygen and pH can easily affect the activity of functional bacteria, and the competition for substrates between heterotrophic denitrifying bacteria and anaerobic ammonia-oxidizing bacteria will reduce the denitrification efficiency. In addition, fluctuations in influent water quality will threaten the stability of nitrite accumulation, and high requirements are placed on process control.

[0004] MABR is a novel wastewater treatment system that combines gas separation membrane technology with biofilm treatment technology. It achieves nearly 100% oxygen transfer efficiency through a unique bubble-free aeration mechanism. This system spontaneously forms a layered ecological structure of aerobic and anoxic microenvironments within the biofilm, enabling efficient simultaneous nitrification and denitrification (SND) and significantly improving denitrification performance. Its core technological advantages lie in: 1) precise regulation of dissolved oxygen through membrane media; 2) optimized biofilm functional zoning to improve microbial community distribution; and 3) significantly enhanced system operational stability and treatment efficiency. Furthermore, the MABR system exhibits outstanding characteristics such as compact structure, energy savings, and good process compatibility.

[0005] The MABR-coupled PD / A process can simultaneously construct a layered biofilm structure with aerobic, anoxic, and anaerobic zones within a single reactor, achieving efficient tandem operation of short-range nitrification and denitrification coupled with anaerobic ammonium oxidation. Furthermore, the reactor protects the functional bacterial flora through biofilm immobilization, significantly improving the system's ability to withstand shock loads. Compared to traditional processes, it reduces energy consumption by over 50%, sludge yield by 40-60%, and floor space by 30%, making it particularly suitable for deep denitrification of low-C / N ratio wastewater. Furthermore, the reactor is a continuous-flow reactor with strong practicality, suitable for large-scale wastewater treatment plants. Its modular tandem design allows for flexible adaptation to varying water quality requirements while reducing floor space. It also requires less automated control and saves energy. The effluent from the post-anoxic MABR reactor is treated in an anaerobic sludge fermentation tank. Anaerobic fermentation hydrolyzes particulate organic matter (such as polysaccharides and proteins) in the sludge into dissolved organic matter (such as volatile fatty acids, VFAs). This high-quality carbon source is then reused in the biological denitrification system, reducing the need for an external carbon source and making it particularly suitable for treating wastewater with a low C / N ratio.

[0006] To address the dual needs of deep denitrification of low-carbon-nitrogen ratio wastewater and energy conservation and consumption reduction in municipal wastewater treatment, and considering the limitations of existing technologies, this paper proposes a synergistic denitrification process combining MABR and PD / A. This process optimizes dissolved oxygen distribution through the MABR's bubble-free aeration and layered biofilm structure, enhancing the efficient tandem operation of short-range denitrification and anaerobic ammonium oxidation. Combined with sludge fermentation carbon source recovery technology, this process forms a sustainable denitrification system with low energy consumption and low sludge yield, providing an innovative solution for deep denitrification and resource utilization in municipal wastewater. Summary of the Invention

[0007] The present invention is based on short-range denitrification coupled anaerobic ammonium oxidation technology, membrane aerated biofilm reactor (MABR) technology, aerobic aeration method, anaerobic fermentation method and sewage treatment process control technology, and provides a deep denitrification and phosphorus removal process using a continuous flow MABR system to achieve simultaneous nitrification and denitrification and enhanced anaerobic ammonium oxidation, so as to achieve efficient denitrification and phosphorus removal of low carbon-nitrogen ratio urban sewage.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A device for achieving deep denitrification and phosphorus removal of low carbon-nitrogen ratio sewage by autotrophic and heterotrophic coupling based on a continuous flow membrane aeration biofilm reactor, characterized in that it comprises a municipal sewage tank (1), an anaerobic tank (2), an anoxic section MABR tank (3), an aerobic aeration tank (4), a post-anoxic section MABR tank (5), a sedimentation tank (6), a sludge carbon source extraction system (7), an intermediate water tank (8), and a water outlet tank (9), wherein the anaerobic tank (2) is provided with a first water inlet pipe (2.1), a first peristaltic pump (2.2), a first water inlet (2.3), a first pH probe (2.4), and a second water outlet pipe (2.5). A DO probe (2.5), a first multi-parameter measuring instrument (2.6), a first mud inlet (2.7), a first stirring device (2.8), an anoxic section MABR tank (3) is provided with a first MABR membrane assembly (3.1), a first air supply pipe (3.2), a second multi-parameter measuring instrument (3.3), a second pH probe (3.4), a second DO probe (3.5), a second stirring device (3.6), an internal reflux water inlet (3.7), a first pressure sensor (3.8), a first aeration valve (3.9), a blower (3.10), an aerobic aeration tank (4) is provided with a third stirring device (4.1), a fourth stirring device (4.2), a second air supply pipe (4.3), an aeration head (4.4), the post-anoxic section MABR tank (5) is provided with a second MABR membrane assembly (5.1), an internal carbon source return port (5.2), a third air supply pipe (5.3), a third aeration valve (5.4), a third pressure sensor (5.5), a first water outlet (5.6), a second peristaltic pump (5.7), a return pipe (5.8), the sedimentation tank (6) is provided with a second water inlet (6.1), a third peristaltic pump (6.2), a third The first outlet pipe (6.3), the first sludge pump (6.4), the first sludge pipe (6.5), the second sludge pump (6.6), the second sludge pipe (6.7) and the second outlet (6.8) of the sludge carbon source extraction system (7) are provided with a second sludge inlet (7.1), an exhaust port (7.2), a condensate outlet (7.3), a third outlet (7.4), a condensate inlet (7.5), a fifth stirring device (7.6), a fourth peristaltic pump (7.7), a second outlet pipe (7.8), and (8) is provided with a fifth peristaltic pump (8.1) and a carbon source pipe (8.2). The municipal sewage tank is connected to the anaerobic tank through the first peristaltic pump. In the continuous flow reaction tank, the anaerobic tank, the anoxic section MABR tank, the aerobic aeration tank and the post-anoxic section MABR tank are connected in sequence. The post-anoxic MABR tank is connected to the sedimentation tank via the third peristaltic pump. A portion of the effluent is returned to the anoxic MABR tank via the second peristaltic pump. The sedimentation tank effluent flows into the outlet tank, where part of the sludge enters the sludge carbon source extraction system for fermentation via the first sludge pump, while part is returned to the anaerobic tank via the second sludge pump. The sludge carbon source extraction system is connected to the intermediate water tank via the fourth peristaltic pump, which in turn is connected to the post-anoxic MABR tank via the fifth peristaltic pump to provide it with a carbon source.

[0010] A method for achieving deep denitrification and phosphorus removal from low carbon-nitrogen ratio sewage by autotrophic and heterotrophic coupling based on a continuous flow membrane aeration biofilm reactor, characterized by comprising the following steps:

[0011] (1) Setting the operating mode of the continuous flow system

[0012] The continuous flow system is divided into an anaerobic tank, an anoxic section MABR tank, an aerobic aeration tank, and a post-anoxic section MABR tank. The volume ratio of each tank is 2:2:2:1 to 2:2:4:1; urban sewage enters the reaction tanks of the continuous flow system in turn, the residual sludge enters the sludge carbon source extraction device, and the generated sludge fermentation products enter the post-anoxic section MABR tank for short-range denitrification utilization, and the return sludge is returned to the anaerobic tank; part of the effluent from the post-anoxic section MABR tank is returned to the anoxic section MABR to achieve deep denitrification.

[0013] (2) Setting parameters, starting and running the system

[0014] During the startup phase, sludge was inoculated into each reaction tank, including excess sludge from the sewage treatment plant, excess sludge from the sewage treatment plant and anaerobic ammonium oxidation sludge, excess sludge from the sewage treatment plant, and excess sludge from the sewage treatment plant and anaerobic ammonium oxidation sludge, so that the sludge concentrations in each reaction tank were 3.0-6.0 gVSS / L, 4.0-8.0 gVSS / L, 2.0-5.0 gVSS / L, and 4.0-8.0 gVSS / L, respectively; part of the effluent from the post-anoxic MABR tank was returned to the anoxic MABR tank, with a mixed liquor return ratio of 200-400%, and the sludge return rate in the sedimentation tank was 70-80%;

[0015] In the anaerobic tank, the initial influent organic load is 0.1~0.2kgCOD / (m 3 d), water inlet flow rate 10~20m 3 / h, hydraulic retention time is 4.0-6.0h, dissolved oxygen is controlled below 0.2mg / L, the phosphorus concentration of the effluent of the anaerobic tank is 2-3 times higher than the phosphorus concentration of the inlet water, and the tank has been running stably for more than 7 days, and the sludge concentration in the anaerobic tank is greater than or equal to 3.0gVSS / L, the anaerobic tank is successfully started;

[0016] In the anoxic MABR tank, the blower was turned on and the aeration device was opened. The pulse aeration mode was adopted, with aeration for 40 minutes and then rest for 20 minutes. The membrane aeration pressure was controlled at 15-25 kPa, the dissolved oxygen concentration was 0.2-0.5 mg / L, and the hydraulic retention time was 4.0-6.0 hours. When the ammonia nitrogen removal rate of the anoxic MABR tank was higher than 60%, the nitrate nitrogen removal rate was higher than 80%, and it had been running stably for more than 7 days, and the sludge concentration on the MABR biofilm was greater than or equal to 1.0 gVSS / L, the anoxic MABR tank was successfully started.

[0017] In the aerobic aeration tank, turn on the blower and open the aeration device. The aeration intensity is calculated as 10 to 20 m2 per unit tank area. 3 / (m 3 h), the hydraulic retention time is 8 to 12 hours, and the dissolved oxygen concentration is controlled at 2 to 4 mg / L; when the influent COD removal rate is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, and the phosphorus removal rate is higher than 85%, and it has been running stably for more than 7 days continuously, the aerobic aeration tank is successfully started;

[0018] In the post-anoxic section MABR pool, add carbon source fermentation liquid to maintain the carbon-nitrogen ratio at 1.2-2.0; turn on the blower and open the aeration device, adopt pulse aeration mode, aerate for 40 minutes, stop for 20 minutes, control the membrane aeration pressure at 15-20KPa, and the DO concentration at 0.2-0.5mg / L; when the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 80%, and the nitrate nitrogen removal rate is higher than 80%, the effluent begins to flow back to the anoxic section MABR pool; when the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 85%, and the nitrate nitrogen removal rate is higher than 85%, and it has been running stably for more than 7 days, the sludge concentration on the MABR biofilm is greater than or equal to 0.8gVSS / L, and the anoxic section MABR pool is successfully started.

[0019] (3) Load increase stage

[0020] Municipal sewage enters the continuous flow reactor and passes through the anaerobic tank, anoxic section MABR tank, aerobic aeration tank, and post-anoxic section MABR tank in sequence; in the anaerobic tank, the organic load of the influent is increased to 0.2-0.3 kgCOD / (m 3 d) The water inlet flow rate is increased to 15-25m 3 / h, the hydraulic retention time is shortened to 3.0-5.0h; when the effluent phosphorus concentration of the anaerobic tank is 2-3 times higher than the influent phosphorus concentration, and it has been running stably for more than 7 days, the influent organic load is adjusted to 0.3-0.4kgCOD / (m 3 d) The water inlet flow rate is increased to 20-30m 3 / h, the hydraulic retention time is shortened to 2.0-4.0h, at this time the anaerobic tank effluent phosphorus concentration is 2-3 times higher than the inlet phosphorus concentration and it can run stably for more than 7 days continuously. The system can operate stably for a long time under this condition;

[0021] In the anoxic section MABR pool, the recirculation ratio is increased to 300-500%, the aeration time is shortened to 35 minutes of aeration and 25 minutes of stop, the membrane aeration pressure is controlled at 17-27 kPa, the dissolved oxygen concentration is 0.4-0.7 mg / L, and the hydraulic retention time is shortened to 3.0-5.0 hours. When the ammonia nitrogen removal rate of the anoxic section MABR pool is higher than 60%, the nitrate nitrogen removal rate is higher than 80%, and they have been running stably for more than 7 days, the recirculation ratio is increased to 400-600%, the aeration time is shortened to 30 minutes of aeration and 30 minutes of stop, the membrane aeration pressure is controlled at 20-30 kPa, the dissolved oxygen concentration is 0.6-0.9 mg / L, and the hydraulic retention time is shortened to 2.0-4.0 hours. At this time, the ammonia nitrogen removal rate of the anoxic section MABR pool is higher than 60%, the nitrate nitrogen removal rate is higher than 80%, and they have been running stably for more than 7 days. The system can operate stably for a long time under this condition.

[0022] In the aerobic aeration tank, shorten the hydraulic retention time to 6.0-10.0h and increase the aeration intensity to 15-25m 3 / (m 3 ·h), the dissolved oxygen concentration is controlled at 2.5-4.5 mg / L, when the influent COD removal rate is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, the phosphorus removal rate is higher than 85%, and it has been running stably for more than 7 days, shorten the hydraulic retention time to 4.0-8.0h, and increase the aeration intensity to 20-30m 3 / (m 3 h), the dissolved oxygen concentration is controlled at 3.0-5.0 mg / L. At this time, the COD removal rate of the aerobic aeration tank influent is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, and the phosphorus removal rate is higher than 85%. The system can operate stably for a long time under this condition.

[0023] In the post-anoxic section MABR pool, the aeration time is shortened to 35 minutes of aeration and 25 minutes of stop, the membrane aeration pressure is controlled at 17-23 kPa, the dissolved oxygen concentration is 0.4-0.7 mg / L, and the hydraulic retention time is shortened to 1.5-2.5 hours accordingly; when the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 85%, the nitrate nitrogen removal rate is higher than 85%, and they have been running stably for more than 7 days, the aeration time is shortened to 30 minutes of aeration and 30 minutes of stop, the membrane aeration pressure is controlled at 19-25 kPa, the dissolved oxygen concentration is 0.6-0.9 mg / L, and the hydraulic retention time is shortened to 1.0-2.0 hours accordingly. At this time, the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 85%, the nitrate nitrogen removal rate is higher than 85%, and they have been running stably for more than 7 days. The system can operate stably for a long time under this condition.

[0024] The continuous flow two-stage membrane aeration biofilm reactor coupled with anaerobic fermentation reactor (MABR) device for realizing short-range denitrification coupled with anaerobic ammonium oxidation and low carbon-nitrogen ratio sewage denitrification provided by the present invention has the following advantages:

[0025] (1) The MABR system uses breathable membrane materials to achieve bubble-free aeration, with a theoretical oxygen transfer efficiency of up to 100%, and can precisely control oxygen concentration. This characteristic creates a unique oxygen concentration gradient for the microorganisms within the biofilm, allowing nitrite bacteria, nitrifying bacteria, and anaerobic ammonium oxidizing bacteria to coexist and work synergistically in the same system, thereby achieving simultaneous nitrification and denitrification. By optimizing the nitrogen conversion pathway, the MABR system significantly improves the denitrification efficiency, especially when treating low carbon-nitrogen ratio wastewater, while still maintaining a high total nitrogen removal rate.

[0026] (2) Anaerobic ammonium oxidizing bacteria grow slowly and are extremely sensitive to changes in environmental conditions. Their growth conditions are very strict, which makes traditional systems less stable during operation and difficult to withstand external shock loads. In contrast, the MABR system provides a stable attachment site for microorganisms through membrane materials, promoting the formation of biofilms. Inside the biofilm, the microbial community presents a hierarchical structure, and different types of microorganisms can grow and reproduce in their respective suitable microenvironments. This hierarchical structure not only provides stable living conditions for anaerobic ammonium oxidizing bacteria, but also enhances the stability of the entire system and significantly improves the system's tolerance to shock loads.

[0027] (3) In actual operation, the traditional short-range denitrification coupled with anaerobic ammonium oxidation reaction requires an organic carbon source. The core advantage of treating the effluent of the activated sludge reactor in an anaerobic sludge fermentation tank is the efficient recovery and recycling of the carbon source. Through anaerobic fermentation, the refractory particulate organic matter in the sludge is hydrolyzed and converted into soluble volatile fatty acids, which are reused as high-quality endogenous carbon sources in the anoxic MABR tank, significantly reducing the dependence on external carbon sources. It is particularly suitable for the treatment of low carbon-nitrogen ratio wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the device of the present invention.

[0029] 1—Municipal sewage tank, 2—Anaerobic tank, 2.1—First water inlet, 2.2—First peristaltic pump, 2.3—First water inlet, 2.4—First pH probe, 2.5—First DO probe, 2.6—First multi-parameter measuring instrument, 2.7—First mud inlet, 2.8—First stirring device, 3—Anoxic section MABR tank, 3.1—First MABR membrane assembly, 3.2—First air supply pipe, 3.3—Second multi-parameter measuring instrument, 3.4—Second pH probe, 3.5—Second DO probe, 3.6—Second stirring device, 3.7—Internal reflux water inlet, 3.8—Second pressure sensor, 3.9—Second aeration valve, 3.10—Blower, 4—Aerobic aeration tank, 4.1—Third stirring device, 4.2—Fourth stirring device, 4.3—Second air supply pipe, 4.4—Aeration head, 5—Post-anoxic section MABR tank, 5.1 —Second MABR membrane assembly, 5.2—Internal carbon source return port, 5.3—Third air supply pipe, 5.4—Third aeration valve, 5.5—Third pressure sensor, 5.6—First water outlet, 5.7—Second peristaltic pump, 5.8—Return pipe, 6—Sedimentation tank, 6.1—Second water inlet, 6.2—Third peristaltic pump, 6.3—First water outlet pipe, 6.4—First mud pump, 6.5—First mud delivery pipe, 6.6—Second Mud pump, 6.7—second mud pipe, 6.8—second water outlet, 7—sludge carbon source extraction system, 7.1—second mud inlet, 7.2—exhaust port, 7.3—condensate outlet, 7.4—third water outlet, 7.5—condensate inlet, 7.6—fifth stirring device, 7.7—fourth peristaltic pump, 7.8—second water outlet pipe, 8—intermediate water tank, 8.1—fifth peristaltic pump, 8.2—carbon source tube, 9—water outlet tank. DETAILED DESCRIPTION

[0030] The present invention is further described in conjunction with the accompanying drawings and embodiments. As shown in the figure, a device for achieving deep denitrification and phosphorus removal of low carbon-nitrogen ratio sewage by autotrophic and heterotrophic coupling based on a continuous flow membrane aeration biofilm reactor is characterized in that it includes a municipal sewage tank (1), an anaerobic tank (2), an anoxic section MABR tank (3), an aerobic aeration tank (4), a post-anoxic section MABR tank (5), a sedimentation tank (6), a sludge carbon source extraction system (7), an intermediate water tank (8), and a water outlet tank (9). The anaerobic tank (2) is provided with a first water inlet pipe (2.1), a first peristaltic pump (2.2), a first water inlet ( 2.3), a first pH probe (2.4), a first DO probe (2.5), a first multi-parameter measuring instrument (2.6), a first mud inlet (2.7), a first stirring device (2.8), the anoxic section MABR tank (3) is provided with a first MABR membrane assembly (3.1), a first air supply pipe (3.2), a second multi-parameter measuring instrument (3.3), a second pH probe (3.4), a second DO probe (3.5), a second stirring device (3.6), an internal reflux water inlet (3.7), a first pressure sensor (3.8), a first aeration valve (3.9), a blower (3.10), the aerobic aeration tank (4) is provided with a third stirring device (4.1), a fourth stirring device (4.2), a second air supply pipe (4.3), an aeration head (4.4), the post-anoxic section MABR tank (5) is provided with a second MABR membrane assembly (5.1), an internal carbon source return port (5.2), a third air supply pipe (5.3), a third aeration valve (5.4), a third pressure sensor (5.5), a first water outlet (5.6), a second peristaltic pump (5.7), a return pipe (5.8), the sedimentation tank (6) is provided with a second water inlet (6.1), a third peristaltic pump ( 6.2), a first outlet pipe (6.3), a first sludge pump (6.4), a first sludge delivery pipe (6.5), a second sludge pump (6.6), a second sludge delivery pipe (6.7), and a second outlet (6.8). The sludge carbon source extraction system (7) is provided with a second sludge inlet (7.1), an exhaust port (7.2), a condensate outlet (7.3), a third outlet (7.4), a condensate inlet (7.5), a fifth stirring device (7.6), a fourth peristaltic pump (7.7), and a second outlet pipe (7.8). (8) is provided with a fifth peristaltic pump (8.1) and a carbon source pipe (8.2). The municipal sewage tank is connected to the anaerobic tank via the first peristaltic pump. In the continuous flow reaction tank, the anaerobic tank, the anoxic section MABR tank, the aerobic aeration tank, and the post-anoxic section MABR tank are connected in sequence. The post-anoxic MABR tank is connected to the sedimentation tank via the third peristaltic pump. A portion of the effluent is returned to the anoxic MABR tank via the second peristaltic pump. The sedimentation tank effluent flows into the outlet tank, where part of the sludge enters the sludge carbon source extraction system for fermentation via the first sludge pump, while part is returned to the anaerobic tank via the second sludge pump. The sludge carbon source extraction system is connected to the intermediate water tank via the fourth peristaltic pump, which in turn is connected to the post-anoxic MABR tank via the fifth peristaltic pump to provide it with a carbon source.

[0031] A method for achieving deep denitrification and phosphorus removal by autotrophic and heterotrophic coupling of low carbon-nitrogen ratio sewage using a continuous flow membrane aeration biofilm reactor comprises the following steps:

[0032] (1) Setting the operating mode of the continuous flow system

[0033] The continuous flow system is divided into an anaerobic tank, an anoxic section MABR tank, an aerobic aeration tank, and a post-anoxic section MABR tank, with the volume ratio of each tank being 2:2:3:1; urban sewage enters the reaction tanks of the continuous flow system in turn, the remaining sludge enters the sludge carbon source extraction device, and the generated sludge fermentation products enter the post-anoxic section MABR tank for short-range denitrification, and the return sludge is returned to the anaerobic tank; part of the effluent from the post-anoxic section MABR tank is returned to the anoxic section MABR to achieve deep denitrification.

[0034] (2) Setting parameters, starting and running the system

[0035] During the startup phase, sludge was inoculated into each reaction tank, including excess sludge from the sewage treatment plant, excess sludge from the sewage treatment plant and anaerobic ammonium oxidation sludge, excess sludge from the sewage treatment plant, and excess sludge from the sewage treatment plant and anaerobic ammonium oxidation sludge, so that the sludge concentrations in each reaction tank were 4.5 gVSS / L, 6.0 gVSS / L, 3.5 gVSS / L, and 6 gVSS / L, respectively. Part of the effluent from the post-anoxic MABR tank was returned to the anoxic MABR tank, with a mixed liquor return ratio of 300%, and the sludge return rate in the sedimentation tank was 75%.

[0036] In the anaerobic tank, the initial influent organic load is 0.15kgCOD / (m 3 d), water inlet flow rate 15m 3 / h, hydraulic retention time is 5.0h, dissolved oxygen is controlled below 0.2mg / L, the phosphorus concentration of the effluent from the anaerobic tank is 2 to 3 times higher than the phosphorus concentration of the inlet water, and it has been running stably for more than 7 days, and the sludge concentration in the anaerobic tank is greater than or equal to 3.0gVSS / L, the anaerobic tank is successfully started.

[0037] In the anoxic MABR tank, the blower was turned on to open the aeration device, and the pulse aeration mode was adopted. The aeration was carried out for 40 minutes and then stopped for 20 minutes. The membrane aeration pressure was controlled at 15-25 kPa, the dissolved oxygen concentration was 0.2-0.5 mg / L, and the hydraulic retention time was 5 hours. When the ammonia nitrogen removal rate of the anoxic MABR tank was higher than 60%, the nitrate nitrogen removal rate was higher than 80%, and the tank had been running stably for more than 7 days, and the sludge concentration on the MABR biofilm was greater than or equal to 1.0 gVSS / L, the anoxic MABR tank was successfully started.

[0038] In the aerobic aeration tank, turn on the blower and open the aeration device. The aeration intensity is calculated as 15m per unit tank area.3 / (m 3 h), the hydraulic retention time is 10 h, and the dissolved oxygen concentration is controlled at 2-4 mg / L; when the influent COD removal rate is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, and the phosphorus removal rate is higher than 85%, and it has been running stably for more than 7 days continuously, the aerobic aeration tank is successfully started;

[0039] In the post-anoxic section MABR pool, carbon source fermentation liquid is added to maintain the carbon-nitrogen ratio at 1.6; the blower is turned on to open the aeration device, and the pulse aeration mode is adopted. The aeration is carried out for 40 minutes and then stopped for 20 minutes. The membrane aeration pressure is controlled at 15-20KPa and the dissolved oxygen concentration is 0.2-0.5mg / L; when the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 80%, and the nitrate nitrogen removal rate is higher than 80%, the effluent begins to flow back to the anoxic section MABR pool; when the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 85%, and the nitrate nitrogen removal rate is higher than 85%, and it has been running stably for more than 7 days, the sludge concentration on the MABR biofilm is greater than or equal to 0.8gVSS / L, and the anoxic section MABR pool is successfully started.

[0040] (3) Load increase stage

[0041] Municipal sewage enters the continuous flow reactor and passes through the anaerobic tank, anoxic section MABR tank, aerobic aeration tank, and post-anoxic section MABR tank in sequence; in the anaerobic tank, the organic load of the influent is increased to 0.25kgCOD / (m 3 d) The water inlet flow rate is increased to 20m 3 / h, the hydraulic retention time is shortened to 4.0h; when the effluent phosphorus concentration of the anaerobic tank is 2 to 3 times higher than the inlet phosphorus concentration, and it has been running stably for more than 7 days, the inlet organic load is adjusted to 0.35kgCOD / (m 3 d) The water inlet flow rate is increased to 25m 3 / h, the hydraulic retention time is shortened to 3.0h, at this time the anaerobic tank effluent phosphorus concentration is 2 to 3 times higher than the inlet phosphorus concentration and it can run stably for more than 7 days continuously. The system can operate stably for a long time under this condition;

[0042] In the anoxic section MABR pool, the recirculation ratio is increased to 400%, the aeration time is shortened to aeration 35 minutes, stop 25 minutes, the membrane aeration pressure is controlled at 22KPa, the dissolved oxygen concentration is 0.4-0.7mg / L, and the hydraulic retention time is shortened to 4.0h accordingly; when the ammonia nitrogen removal rate of the anoxic section MABR pool is higher than 60%, the nitrate nitrogen removal rate is higher than 80%, and they have been running stably for more than 7 days, the recirculation ratio is increased to 500%, the aeration time is shortened to aeration 30 minutes, stop 30 minutes, the membrane aeration pressure is controlled at 20-30KPa, the dissolved oxygen concentration is 0.6-0.9mg / L, and the hydraulic retention time is shortened to 3.0h accordingly. At this time, the ammonia nitrogen removal rate of the anoxic section MABR pool is higher than 60%, the nitrate nitrogen removal rate is higher than 80%, and they have been running stably for more than 7 days. The system can operate stably for a long time under this condition;

[0043] In the aerobic aeration tank, shorten the hydraulic retention time to 8.0h and increase the aeration intensity to 15-25m 3 / (m 3 ·h), the dissolved oxygen concentration is controlled at 2.5-4.5 mg / L, when the influent COD removal rate is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, the phosphorus removal rate is higher than 85%, and it has been running stably for more than 7 days, shorten the hydraulic retention time to 6.0h, and increase the aeration intensity to 25m 3 / (m 3 h), the dissolved oxygen concentration is controlled at 4.0 mg / L. At this time, the COD removal rate of the aerobic aeration tank is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, and the phosphorus removal rate is higher than 85%. The system operates stably for more than 7 days continuously. Under this condition, the system operates stably for a long time.

[0044] In the post-anoxic section MABR pool, the aeration time is shortened to 35 minutes of aeration and 25 minutes of stop, the membrane aeration pressure is controlled at 17-23 kPa, the dissolved oxygen concentration is 0.4-0.7 mg / L, and the hydraulic retention time is shortened to 2.0 hours accordingly; when the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 85%, the nitrate nitrogen removal rate is higher than 85%, and they have been running stably for more than 7 days, the aeration time is shortened to 30 minutes of aeration and 30 minutes of stop, the membrane aeration pressure is controlled at 19-25 kPa, the dissolved oxygen concentration is 0.6-0.9 mg / L, and the hydraulic retention time is shortened to 1.5 hours accordingly. At this time, the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 85%, the nitrate nitrogen removal rate is higher than 85%, and they have been running stably for more than 7 days. The system can operate stably for a long time under this condition.

[0045] The specific test water was taken from a city domestic sewage treatment plant. The average ammonia nitrogen concentration was 98.2 mg / L, the average phosphorus concentration was 6.3 mg / L, and the COD concentration was 203.7 mg / L. After 120 days of long-term operation, the effluent ammonia nitrogen concentration was 8.3 mg / L, the nitrate nitrogen removal rate was 86.7%, and the effluent phosphorus concentration was 0.4 mg / L, achieving stable and deep denitrification of urban sewage.

Claims

1. A device for achieving deep denitrification and phosphorus removal of low carbon-nitrogen ratio sewage by autotrophic and heterotrophic coupling based on a continuous flow membrane aeration biofilm reactor, characterized in that: The system comprises a municipal sewage tank (1), an anaerobic tank (2), an anoxic section MABR tank (3), an aerobic aeration tank (4), a post-anoxic section MABR tank (5), a sedimentation tank (6), a sludge carbon source extraction system (7), an intermediate water tank (8), and an outlet tank (9). The anaerobic tank (2) is provided with a first water inlet pipe (2.1), a first peristaltic pump (2.2), a first water inlet (2.3), a first pH probe (2.4), a first DO probe (2.5), a first multi-parameter measuring instrument (2.6), a first mud inlet (2.7), and a first stirring device (2.8). The anoxic section MABR tank (3) is provided with a first MABR membrane assembly (3.1), a first air supply pipe (3.2), a second multi-parameter measuring instrument (3.9), and a second air supply pipe (3.10). .3), a second pH probe (3.4), a second DO probe (3.5), a second stirring device (3.6), an internal reflux inlet (3.7), a first pressure sensor (3.8), a first aeration valve (3.9), and a blower (3.10). The aerobic aeration tank (4) is provided with a third stirring device (4.1), a fourth stirring device (4.2), a second air supply pipe (4.3), an aeration head (4.4), a second pressure sensor (4.5), and a second aeration valve (4.6). The post-anoxic section MABR tank (5) is provided with a second MABR membrane assembly (5.1), an internal carbon source reflux inlet (5.2), a third air supply pipe (5.3), a third aeration valve (5.4), a third pressure sensor (5.5), and a second aeration valve (5.6). .5), a first water outlet (5.6), a second peristaltic pump (5.7), a reflux pipe (5.8), the sedimentation tank (6) is provided with a second water inlet (6.1), a third peristaltic pump (6.2), a first water outlet pipe (6.3), a first sludge pump (6.4), a first sludge delivery pipe (6.5), a second sludge pump (6.6), a second sludge delivery pipe (6.7), a second water outlet (6.8), the sludge carbon source extraction system (7) is provided with a second sludge inlet (7.1), an exhaust port (7.2), a condensate outlet (7.3), a third water outlet (7.4), a condensate inlet (7.5), a fifth stirring device (7.6), a fourth peristaltic pump (7.7), a second water outlet pipe (7.8), and the intermediate water tank (8) is provided with There is a fifth peristaltic pump (8.1) and a carbon source pipe (8.2); the urban sewage tank is connected to the anaerobic tank through the first peristaltic pump, and the anaerobic tank, the anoxic section MABR tank, the aerobic aeration tank, and the post-anoxic section MABR tank are connected in sequence in the continuous flow reaction tank; the post-anoxic section MABR tank is connected to the sedimentation tank through the third peristaltic pump, and part of the effluent is returned to the anoxic section MABR tank through the second peristaltic pump; the effluent of the sedimentation tank flows to the outlet tank, and the remaining sludge enters the sludge carbon source extraction system for fermentation through the first sludge pump, and the return sludge is returned to the anaerobic tank through the second sludge pump; the sludge carbon source extraction system is connected to the intermediate water tank through the fourth peristaltic pump, and the intermediate water tank is connected to the post-anoxic section MABR tank through the fifth peristaltic pump to provide it with a carbon source.

2. A method for applying the device according to claim 1, characterized in that: The following steps are involved: (1) Setting the operating mode of the continuous flow system The continuous flow system is divided into an anaerobic tank, an anoxic section MABR tank, an aerobic aeration tank, and a post-anoxic section MABR tank. The volume ratio of each tank is 2:2:2:1 to 2:2:4:

1. Municipal sewage enters each reaction tank of the continuous flow system in sequence. The residual sludge enters the sludge carbon source extraction device. The generated sludge fermentation products enter the post-anoxic section MABR tank for short-range denitrification utilization, and the return sludge is returned to the anaerobic tank. The effluent of the post-anoxic section MABR tank is partially returned to the anoxic section MABR to achieve deep denitrification. (2) Setting parameters, starting and running During the startup phase, sludge was inoculated into each reaction tank, including excess sludge from the sewage treatment plant, excess sludge from the sewage treatment plant and anaerobic ammonium oxidation sludge, excess sludge from the sewage treatment plant, and excess sludge from the sewage treatment plant and anaerobic ammonium oxidation sludge, so that the sludge concentrations in each reaction tank were 3.0-6.0 gVSS / L, 4.0-8.0 gVSS / L, 2.0-5.0 gVSS / L, and 4.0-8.0 gVSS / L, respectively; part of the effluent from the post-anoxic MABR tank was returned to the anoxic MABR tank, with a mixed liquor return ratio of 200-400%, and the sludge return rate in the sedimentation tank was 70-80%; In the anaerobic tank, the initial influent organic load is 0.1~0.2kgCOD / (m 3 d), water inlet flow rate 10~20m 3 / h, hydraulic retention time is 4.0-6.0h, dissolved oxygen is controlled below 0.2mg / L, the phosphorus concentration of the effluent of the anaerobic tank is 2-3 times higher than the phosphorus concentration of the inlet water, and the tank has been running stably for more than 7 days, and the sludge concentration in the anaerobic tank is greater than or equal to 3.0gVSS / L, the anaerobic tank is successfully started; In the anoxic MABR tank, the blower was turned on to open the aeration device, and the pulse aeration mode was adopted. The aeration was carried out for 40 minutes and then stopped for 20 minutes. The membrane aeration pressure was controlled at 15-25 kPa, the dissolved oxygen concentration was 0.2-0.5 mg / L, and the hydraulic retention time was 4-6 hours. When the ammonia nitrogen removal rate of the anoxic MABR tank was higher than 60%, the nitrate nitrogen removal rate was higher than 80%, and the tank had been running stably for more than 7 days, and the sludge concentration on the MABR biofilm was greater than or equal to 1.0 gVSS / L, the anoxic MABR tank was successfully started. In the aerobic aeration tank, turn on the blower and open the aeration device. The aeration intensity is calculated as 10 to 20 m2 per unit tank area. 3 / (m 3 h), the hydraulic retention time is 8 to 12 hours, and the dissolved oxygen concentration is controlled at 2 to 4 mg / L; when the influent COD removal rate is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, and the phosphorus removal rate is higher than 85%, and it has been running stably for more than 7 days continuously, the aerobic aeration tank is successfully started; In the post-anoxic MABR tank, add carbon source fermentation liquid to maintain the carbon-nitrogen ratio at 1.2-2.0; Turn on the blower and aeration device, adopt pulse aeration mode, aerate for 40 minutes, stop for 20 minutes, control the membrane aeration pressure at 15-20 kPa, and the DO concentration at 0.2-0.5 mg / L; when the ammonia nitrogen removal rate of the post-anoxic MABR pool is higher than 80%, and the nitrate nitrogen removal rate is higher than 80%, the effluent begins to flow back to the anoxic MABR pool; when the ammonia nitrogen removal rate of the post-anoxic MABR pool is higher than 85%, and the nitrate nitrogen removal rate is higher than 85%, and it has been running stably for more than 7 days, and the sludge concentration on the MABR biofilm is greater than or equal to 0.8 gVSS / L, the anoxic MABR pool is successfully started; (3) Load increase stage Municipal sewage enters the continuous flow reactor and passes through the anaerobic tank, anoxic section MABR tank, aerobic aeration tank, and post-anoxic section MABR tank in sequence; in the anaerobic tank, the organic load of the influent is increased to 0.2-0.3 kgCOD / (m 3 d) The water inlet flow rate is increased to 15-25m 3 / h, the hydraulic retention time is shortened to 3.0-5.0h; when the effluent phosphorus concentration of the anaerobic tank is 2-3 times higher than the influent phosphorus concentration, and it has been running stably for more than 7 days, the influent organic load is adjusted to 0.3-0.4kgCOD / (m 3 d) The water inlet flow rate is increased to 20-30m 3 / h, the hydraulic retention time is shortened to 2.0-4.0h, and it can be operated for a long time under this condition; In the anoxic section of the MABR pool, the recirculation ratio is increased to 300-500%, the aeration time is shortened to 35 minutes of aeration and 25 minutes of stop, the membrane aeration pressure is controlled at 17-27 kPa, the dissolved oxygen concentration is 0.4-0.7 mg / L, and the hydraulic retention time is shortened to 3.0-5.0 hours accordingly; when the ammonia nitrogen removal rate of the anoxic section MABR pool is higher than 60%, the nitrate nitrogen removal rate is higher than 80%, and it has been running stably for more than 7 days, the recirculation ratio is increased to 400-600%, the aeration time is shortened to 30 minutes of aeration and 30 minutes of stop, the membrane aeration pressure is controlled at 20-30 kPa, the dissolved oxygen concentration is 0.6-0.9 mg / L, and the hydraulic retention time is shortened to 2.0-4.0 hours accordingly, and it can be operated for a long time under these conditions; In the aerobic aeration tank, shorten the hydraulic retention time to 6.0-10.0h and increase the aeration intensity to 15-25m 3 / (m 3 ·h), the dissolved oxygen concentration is controlled at 2.5-4.5 mg / L, when the influent COD removal rate is higher than 80%, the ammonia nitrogen removal rate is higher than 80%, the phosphorus removal rate is higher than 85%, and it has been running stably for more than 7 days, shorten the hydraulic retention time to 4.0-8.0h, and increase the aeration intensity to 20-30m 3 / (m 3 h), the dissolved oxygen concentration is controlled at 3.0-5.0 mg / L and operated under this condition for a long time; In the post-anoxic section MABR pool, the aeration time is shortened to 35 minutes of aeration and 25 minutes of stop, the membrane aeration pressure is controlled at 17-23KPa, the dissolved oxygen concentration is 0.4-0.7mg / L, and the hydraulic retention time is shortened to 1.5-2.5h accordingly; when the ammonia nitrogen removal rate of the post-anoxic section MABR pool is higher than 85%, the nitrate nitrogen removal rate is higher than 85%, and it has been running stably for more than 7 days, the aeration time is shortened to 30 minutes of aeration and 30 minutes of stop, the membrane aeration pressure is controlled at 19-25KPa, the dissolved oxygen concentration is 0.6-0.9mg / L, and the hydraulic retention time is shortened to 1.0-2.0h accordingly, and it can be operated for a long time under this condition.

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