Method for autotrophic denitrification in powder carrier process based on micro-aerobic intermittent aeration
By employing microaerobic intermittent aeration and anaerobic stirring in the powder carrier process, the enrichment of ammonia-oxidizing bacteria and anaerobic ammonia-oxidizing bacteria is promoted, forming a granular symbiosis. This solves the problem of autotrophic denitrification in the powder carrier process and achieves efficient and stable wastewater denitrification.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TONGJI UNIV
- Filing Date
- 2024-02-29
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies struggle to achieve autotrophic nitrogen removal in powder carrier processes, and the slow growth rate of anaerobic ammonia-oxidizing bacteria leads to low nitrogen removal efficiency in wastewater treatment plants, long process start-up cycles, and difficulty in stable operation.
The method of intermittent microaerobic aeration is adopted. Nitrifying sludge and anaerobic ammonia oxidation sludge are inoculated in the SBR reactor and powdered carrier is added. Through intermittent microaerobic aeration and anaerobic stirring, the directional enrichment of ammonia oxidizing bacteria and anaerobic ammonia oxidizing bacteria is promoted, forming a granular symbiosis with ammonia oxidizing bacteria/denitrifying bacteria/anaerobic ammonia oxidizing bacteria as the dominant bacterial group, thereby achieving autotrophic denitrification.
It improves the stability of autotrophic denitrification performance, enhances wastewater denitrification effect, achieves deep reduction of pollutants and low-consumption operation of the process, and meets national emission standards.
Smart Images
Figure CN117985855B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of autotrophic nitrogen removal technology for wastewater, and in particular to a method for autotrophic nitrogen removal in powder carrier processes based on intermittent microaerobic aeration. Background Technology
[0002] In recent years, my country's wastewater treatment volume and capacity have significantly improved. However, the eutrophication problem caused by the excessive discharge of nutrients such as nitrogen and phosphorus has become increasingly serious. The main challenge for wastewater treatment plants has shifted from the removal of organic matter to the control of nitrogen and phosphorus pollutants. Phosphorus removal in wastewater treatment plants can be achieved through biological and chemical methods, with chemical removal being simpler to operate and more effective. However, for nitrogen removal, biological denitrification is the only viable method. Therefore, in the face of stringent discharge standards, deep reduction of total nitrogen is crucial. Current biological denitrification processes remove nitrogen from wastewater through nitrification-denitrification, which generally suffers from long process flows, high energy consumption, and difficulty in further improving efficiency. Anaerobic ammonium oxidation (ANAO), as a novel, highly efficient, and low-energy-consumption biological denitrification technology, has received widespread attention from researchers in recent years. In practical applications, ANAO is often coupled with nitrification to jointly remove nitrogen from wastewater, a process known as short-cut nitrification-anaerobic ammonium oxidation (ATAO) or autotrophic denitrification. However, due to the characteristics of low ammonia nitrogen concentration and fluctuating temperature in mainstream urban wastewater, and the slow growth rate of anaerobic ammonia oxidizing bacteria, a fully autonomous autotrophic denitrification process has yet to be developed.
[0003] The biofilm formation process by introducing carriers into biological treatment tanks has proven to be an effective way to enrich anaerobic ammonia-oxidizing bacteria and achieve autotrophic denitrification. However, the process typically has a long start-up period and is difficult to maintain stable operation in the long term. Powder carrier processes have shown good treatment performance in denitrification and phosphorus removal in urban wastewater, effectively enhancing denitrification. However, existing technologies still lack effective control strategies for achieving autotrophic denitrification in powder carrier processes to further improve wastewater treatment performance. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for autotrophic denitrification in powder carrier processes based on microaerobic intermittent aeration. By adding powder carriers, micro-particle sludge with powder carriers as the core is quickly obtained. The aeration mode is controlled to promote the directional enrichment of ammonia-oxidizing bacteria and anaerobic ammonia-oxidizing bacteria, and a granular symbiotic with ammonia-oxidizing bacteria / denitrifying bacteria / anaerobic ammonia-oxidizing bacteria as the dominant bacterial group is stably cultivated. This achieves stable autotrophic denitrification performance in powder carrier processes and increases the contribution of anaerobic ammonia oxidation pathway in mainstream wastewater treatment.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] The purpose of this invention is to provide a method for autotrophic denitrification in powder carrier processes based on intermittent microaerobic aeration, the method comprising the following steps:
[0007] Nitrified sludge was inoculated into the SBR reactor, with a sludge concentration (MLSS) of 1500–2000 mg / L after inoculation. Then, crushed anammox sludge (particle size <100 mesh) was added, resulting in an MLSS concentration of 3500–4500 mg / L in the SBR reactor. After inoculation with both nitrified and anammox sludge, 2.0–3.5 g / L of powdered carrier was added to complete the inoculation and start-up process. After inoculation and start-up, the reactor was directly adapted to operation for one week using microaerobic aeration. Afterward, the SBR reactor was operated with actual domestic sewage as influent, with an influent time of 5 minutes, a temperature of 25–32℃, an influent pH of 7.6–8.0, and a DO concentration of 0.1–0.6 mg / L.
[0008] One week after inoculation (i.e., after a one-week adaptation period, during which DO = 0.1–0.6 mg / L), the system is operated in an anaerobic stirring + micro-aerobic intermittent aeration stirring mode to denitrify the wastewater. During the micro-aerobic intermittent aeration stage, the dissolved oxygen concentration is maintained at 0.5–1.0 mg / L, the sedimentation and drainage time is 10 min, the drainage ratio is 40%–70%, and the sludge age is controlled at 25–35 days.
[0009] The hydrocyclone separator is started during the micro-aerobic intermittent aeration stage, transporting the mud-water mixture to the hydrocyclone separator. After the separation operation, the powder carrier and some of the microorganisms in the inner layer of the biofilm adsorbed on the surface of the powder carrier are returned to the SBR reactor, and the remaining flocculent sludge is discharged from the system.
[0010] Furthermore, the method is implemented based on a powder carrier device; the powder carrier device includes an inlet tank, an SBR reactor, an outlet tank, and a hydrocyclone separator; the inlet tank is connected to the SBR reactor; the outlet tank is connected to the SBR reactor; and the hydrocyclone separator is connected to the SBR reactor.
[0011] Furthermore, the inlet tank is connected to the SBR reactor via peristaltic pump I; the SBR reactor includes an SBR reactor body, which is equipped with a stirrer, an aeration pump, a gas flow meter, an aeration disc, an online dissolved oxygen monitor, a constant temperature water bath system, an inlet, an outlet I, an outlet II, an overflow outlet, and an air vent; the outlet tank is connected to the SBR reactor via an outlet solenoid valve; the hydrocyclone separator is connected to the SBR reactor via peristaltic pump II; and the hydrocyclone separator is connected to the SBR reactor via peristaltic pump III.
[0012] Furthermore, in the steps of the method: the hydrocyclone separator is started during the micro-aerobic intermittent aeration stage, peristaltic pump II transports the mud-water mixture to the hydrocyclone separator, after the cyclone separation operation, the powder carrier and some of the microorganisms adsorbed on the surface of the powder carrier are returned to the SBR reactor by peristaltic pump III, and the remaining flocculent sludge is discharged from the system.
[0013] Furthermore, the aeration / stop time ratio during the intermittent micro-aeration stage is 0.4 to 0.6.
[0014] Furthermore, the micro-aerobic intermittent aeration stage operates in an aeration + aeration stop mode, undergoing multiple aeration + aeration stop cycles.
[0015] Furthermore, the sedimentation and drainage stage is set in the aeration-stopping stage of the last aeration + aeration-stopping process.
[0016] More preferably, after one week of adaptation to microaerobic aeration, the system is operated with anaerobic stirring + microaerobic intermittent aeration stirring. The microaerobic intermittent aeration process is operated with an aeration / stop time of 40min / 80min, and a total of 2 aeration and stop aeration cycles are performed. During the aeration stage, the dissolved oxygen concentration is maintained at 0.5-1.0mg / L. The sedimentation and drainage stage is set in the last stop aeration stage, with a time of 10min, a drainage ratio of 50%, and a sludge age controlled at 30 days.
[0017] Furthermore, the powder carrier is diatomaceous earth powder with a particle size of 75-120 micrometers.
[0018] Furthermore, the hydrocyclone separator operates at a speed of 190–250 r / min and a cyclone separation time of 1.0–2.0 min.
[0019] Furthermore, the nitrified sludge is suspended flocculent sludge taken from the aerobic zone of the wastewater treatment plant.
[0020] Furthermore, the crushed anammox sludge is anammox granular sludge that has been crushed before use.
[0021] Furthermore, the wastewater is actual domestic sewage; the composition of the wastewater includes chemical oxygen demand of 150-300 mg / L, ammonia nitrogen of 25-50 mg / L, nitrite nitrogen of 0-0.2 mg / L, and nitrate nitrogen of 0.1-1.5 mg / L.
[0022] Furthermore, the anaerobic stirring time is 120 min (including 5 min of water intake time); the microaerobic intermittent aeration stirring time is 240 min.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] This invention proposes a method for autotrophic denitrification in a powder carrier process based on intermittent microaerobic aeration. By adding the powder carrier, microorganisms can rapidly attach and form micro-particle sludge. Under the action of intermittent microaerobic aeration, ammonia-oxidizing bacteria are enriched, while nitrite-oxidizing bacteria are inhibited. This gradually forms a granular symbiosis with ammonia-oxidizing bacteria / denitrifying bacteria / anaerobic ammonia-oxidizing bacteria as the dominant bacterial group. This achieves synergistic denitrification through denitrification, short-cut nitrification, and anaerobic ammonia oxidation, improving the stability of autotrophic denitrification performance and thus enhancing wastewater denitrification performance. This results in deep pollutant reduction and low-consumption operation of the process, with broad application prospects. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the powder carrier device for the method of autotrophic denitrification in the powder carrier process based on micro-aerobic intermittent aeration according to the present invention.
[0026] In the picture:
[0027] 1 – Inlet tank; 2 – SBR reactor; 3 – Outlet tank; 4 – Hydrocyclone separator; 1.1 – Peristaltic pump I; 2.1 – Agitator; 2.2 – Aeration pump; 2.3 – Gas flow meter; 2.4 – Aeration disc; 2.5 – Dissolved oxygen online monitor; 2.6 – Constant temperature water bath system; 2.7 – Outlet; 2.8 – Outlet I; 2.9 – Outlet II; 2.10 – Overflow port; 2.11 – Drain port; 3.1 – Outlet solenoid valve; 4.1 – Peristaltic pump II; 4.2 – Peristaltic pump III. Detailed Implementation
[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.
[0029] This invention belongs to the field of wastewater autotrophic denitrification technology, specifically a method for autotrophic denitrification in a powder carrier process based on microaerobic intermittent aeration. The apparatus includes an influent tank, an SBR reactor, an effluent tank, and a hydrocyclone separator. After inoculation with nitrifying sludge and anaerobic ammonia oxidation sludge, powder carriers with a particle size of 75–120 micrometers are added, and the powder carrier process is operated in an anaerobic stirring / microaerobic intermittent aeration stirring mode (aeration / stop time = 0.4–0.6, dissolved oxygen in the aeration section 0.5–1.0 mg / L). This invention, through the addition of powder carriers and the operation of microaerobic intermittent aeration, achieves stable cultivation of ammonia oxidation / denitrification bacteria / anaerobic ammonia oxidation bacteria granular symbiosis, improves the stability of autotrophic denitrification performance in the powder carrier process, promotes the synergistic denitrification effect of denitrification and short-cut nitrification anaerobic ammonia oxidation, and realizes improved wastewater denitrification performance and low-consumption operation of the powder carrier process, with broad application prospects.
[0030] Example
[0031] like Figure 1 As shown, a method for autotrophic denitrification in a powder carrier process based on intermittent microaerobic aeration is disclosed. The powder carrier device includes an inlet tank 1, an SBR reactor 2, an outlet tank 3, and a hydrocyclone separator 4. The inlet tank 1 is connected to the SBR reactor 2. The outlet tank 3 is connected to the SBR reactor 2. The hydrocyclone separator 4 is connected to the SBR reactor 2.
[0032] The inlet tank 1 is connected to the SBR reactor 2 via a peristaltic pump I 1.1. The SBR reactor 2 includes an SBR reactor body, which is equipped with a stirrer 2.1, an aeration pump 2.2, a gas flow meter 2.3, an aeration disc 2.4, an online dissolved oxygen monitor 2.5, a constant temperature water bath system 2.6, an inlet 2.7, an outlet I 2.8, an outlet II 2.9, an overflow port 2.10, and a drain port 2.11. The outlet tank 3 is equipped with an outlet solenoid valve 3.1. The hydrocyclone separator 4 is equipped with a peristaltic pump II 4.1 and a peristaltic pump III 4.2. The SBR reactor 2 is made of plexiglass and has an effective volume of 4L. The outlet tank 3 is connected to the SBR reactor 2 via an outlet solenoid valve 3.1. The hydrocyclone separator 4 is connected to the SBR reactor 2 via a peristaltic pump II 4.1. The hydrocyclone separator 4 is connected to the SBR reactor 2 via a peristaltic pump III 4.2.
[0033] The inoculated sludge was taken from the nitrification sludge of the aerobic zone of the biochemical treatment unit of a wastewater treatment plant in Shanghai. After inoculation, the sludge concentration MLSS in the system was 1750±56 mg / L. Further, crushed anammox granular sludge (commercially available product, crushed sludge particle size <100 mesh) was added, bringing the sludge concentration MLSS in the reactor to 4320±25 mg / L. Then, 2.0 g / L of diatomaceous earth powder carrier with a particle size of 90±10 micrometers was added to complete the inoculation start-up. The inoculation sludge was successfully inoculated. After startup, the SBR reactor was directly adapted to operation for one week using micro-aerobic aeration. After that, the reactor was operated with actual domestic sewage as the influent, with an influent time of 5 minutes, a temperature of 28±1℃, an influent pH of 7.8±0.2, and DO of 0.1~0.6mg / L. The actual domestic sewage was taken from the septic tank of Tongji University's residential area, and the influent water quality characteristics were: chemical oxygen demand 192±21mg / L, ammonia nitrogen 35±8mg / L, nitrite nitrogen 0.05±0.02mg / L, and nitrate nitrogen 0.2±0.1mg / L.
[0034] After one week of adaptation to microaerobic aeration, the system was operated with anaerobic stirring / microaerobic intermittent aeration stirring (120 min (including 5 min of influent time) / 240 min) to denitrify the wastewater. The stirring rate of anaerobic stirring was 150 r / min, and the stirring rate of intermittent aeration stirring was 150 r / min. The microaerobic intermittent aeration process was operated with an aeration / stop time of 40 min / 80 min, and a total of 2 aeration and stop aeration cycles were performed. During the aeration phase, the dissolved oxygen concentration was maintained at 0.5-1.0 mg / L. The sedimentation and drainage phase was set during the last stop aeration phase, lasting 10 min, with a drainage ratio of 50%, and the sludge age was controlled at 30 days. At the end of the second aeration stage in the micro-aerobic intermittent aeration phase, peristaltic pump II 4.1 is started to transport 300 mL of mud-water mixture to hydrocyclone separator 4. After cyclone separation at 200 r / min for 1 min, 170 mL of the upper layer mixture is returned to SBR reactor 2 by peristaltic pump III 4.2, and the remaining 130 mL of mixture at the bottom is discharged from the system.
[0035] Meanwhile, a control group was set up, which operated under the same conditions as the above implementation plan except that it used an anaerobic / aerobic / hypoxic (120min / 80min / 160min) operating mode.
[0036] The experimental results showed that after 45 days of system operation (after sludge inoculation and a one-week microaerobic aeration adaptation period, the system operated for 45 days using either an anaerobic + intermittent aeration model or an anaerobic + aerobic + anoxic operation mode), the control group using the anaerobic + aerobic + anoxic (120min / 80min / 160min) operation mode achieved a COD removal rate of over 85% and a total nitrogen removal rate of over 70%, with anaerobic ammonia oxidation contributing 34% to nitrogen removal. In contrast, the experimental group based on microaerobic intermittent aeration achieved a COD removal rate of over 95% and a total nitrogen removal rate of over 95%, with autotrophic nitrogen removal contributing 65%, meeting the national Class A effluent discharge standard.
[0037] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A method for autotrophic denitrification in powder carrier processes based on intermittent microaerobic aeration, characterized in that, The method is implemented based on a powder carrier device; The powder carrier device includes an inlet tank (1), an SBR reactor (2), an outlet tank (3), and a hydrocyclone separator (4). The inlet tank (1) is connected to the SBR reactor (2); The effluent tank (3) is connected to the SBR reactor (2); The hydrocyclone separator (4) is connected to the SBR reactor (2); The method includes the following steps: Nitrified sludge was inoculated into the SBR reactor (2), and the sludge concentration MLSS after inoculation was 1500~2000mg / L; then crushed anammox sludge was added, and the sludge concentration MLSS in the SBR reactor (2) after addition was 3500~4500mg / L; after the inoculation of nitrified sludge and anammox sludge was completed, 2.0~3.5g / L of powdered carrier was added to complete the inoculation start-up; after the inoculation sludge was inoculated and started up, micro-aerobic aeration was directly used to adapt to operation for one week, and then the SBR reactor (2) was operated with actual domestic sewage as influent, the temperature was 25~32℃, the influent pH was 7.6~8.0, and DO was 0.1~0.6mg / L. One week after inoculation, the system was operated in an anaerobic stirring + micro-aerobic intermittent aeration stirring mode to denitrify the wastewater. During the micro-aerobic intermittent aeration stage, the dissolved oxygen concentration was maintained at 0.5~1.0 mg / L, the sedimentation and drainage time was 10 min, the drainage ratio was 40%~70%, and the sludge age was controlled at 25~35 days. The hydrocyclone separator (4) is started in the micro-aerobic intermittent aeration stage. The aeration / stop time ratio of the micro-aerobic intermittent aeration stage is 0.4~0.
6. The micro-aerobic intermittent aeration stage is operated in the aeration + stop mode, and undergoes multiple aeration + stop. The sedimentation and drainage stage is set in the stop stage of the last aeration + stop. The mud-water mixture is transported to the hydrocyclone separator (4). After the cyclone separation operation, the powder carrier and the microorganisms in the inner layer of the biofilm adsorbed on the surface of the powder carrier are returned to the SBR reactor (2), and the remaining flocculent sludge is discharged from the system. The inlet tank (1) is connected to the SBR reactor (2) via a peristaltic pump I (1.1); The SBR reactor (2) includes an SBR reactor body, which is equipped with a stirrer (2.1), an aeration pump (2.2), a gas flow meter (2.3), an aeration disc (2.4), an online dissolved oxygen monitor (2.5), a constant temperature water bath system (2.6), an inlet (2.7), an outlet I (2.8), an outlet II (2.9), an overflow outlet (2.10), and an vent outlet (2.11). The effluent tank (3) is connected to the SBR reactor (2) via an effluent solenoid valve (3.1); The hydrocyclone separator (4) is connected to the SBR reactor (2) via a peristaltic pump II (4.1); The hydrocyclone separator (4) is connected to the SBR reactor (2) via a peristaltic pump III (4.2).
2. The method for autotrophic denitrification in a powder carrier process based on intermittent microaerobic aeration according to claim 1, characterized in that, The powder carrier is diatomaceous earth powder with a particle size of 75-120 micrometers.
3. The method for autotrophic denitrification in a powder carrier process based on intermittent microaerobic aeration according to claim 1, characterized in that, The hydrocyclone separator (4) operates at a speed of 190~250 r / min and a cyclone separation time of 1.0~2.0 min.
4. The method for autotrophic denitrification in a powder carrier process based on intermittent microaerobic aeration according to claim 1, characterized in that, The wastewater in question is actual domestic wastewater; The wastewater contains 150-300 mg / L of chemical oxygen demand, 25-50 mg / L of ammonia nitrogen, 0-0.2 mg / L of nitrite nitrogen, and 0.1-1.5 mg / L of nitrate nitrogen.
5. The method for autotrophic denitrification in a powder carrier process based on intermittent microaerobic aeration according to claim 1, characterized in that, The anaerobic stirring time is 120 minutes, including a 5-minute water inlet time; The intermittent microaerobic aeration and stirring time is 240 min.