Device and method for denitrification based on in-situ bacteria-algae rapid establishment of short-cut nitrification denitrification enhanced AOA process

Abstract

The application discloses a device and method for denitrification based on in-situ bacteria-algae for quickly establishing short-path nitrification and denitrification enhanced AOA process. The application couples a short-path in-situ bacteria-algae symbiotic system with an AOA process to construct an efficient denitrification system, effectively reduces aeration energy consumption and external carbon source adding demand, significantly reduces operation cost, realizes deep denitrification, and has a wide application prospect in the field of urban domestic sewage denitrification treatment.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment and resource utilization technology, and relates to a device and method for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae. Background Technology

[0002] With the rapid development of human activities and society, the global ecological environment is becoming increasingly severe. Traditional nitrification-denitrification nitrogen removal processes rely on energy-intensive aeration to maintain the activity of aerobic microorganisms. Simultaneously, to meet effluent requirements, large amounts of external carbon sources need to be added. The energy consumption from aeration and the additional costs of adding carbon sources significantly increase the cost of wastewater treatment. Furthermore, the large amounts of greenhouse gases generated during the decomposition of organic matter are difficult to adapt to the energy conservation and emission reduction targets under the "dual carbon" objective. Therefore, it is necessary to develop a new "low-carbon and high-efficiency" wastewater treatment technology to break through the high-carbon lock-in dilemma of traditional processes and promote the sustainable development of the wastewater treatment industry.

[0003] AOA process is a novel biological nitrogen and phosphorus removal process that optimizes traditional AOA technology. 2 The / O process enhances the treatment efficiency of wastewater with a low C / N ratio. Algal-bacterial symbiotic systems demonstrate significant advantages in wastewater treatment, becoming a green alternative to the traditional activated sludge process. These hybrid biological systems form a healthy symbiotic relationship based on complementary metabolic functions: algae provide dissolved oxygen to promote organic matter degradation, while the CO2 produced by bacterial metabolism serves as a photosynthetic substrate for algae. The synergistic effect of both has great potential in reducing wastewater treatment costs (such as energy consumption for aeration and external carbon sources) and reducing carbon emissions.

[0004] Short-cut biological nitrogen removal technology significantly improves nitrogen removal efficiency and reduces energy consumption by optimizing the traditional nitrification-denitrification pathway. Currently, there is limited research on the combined use of algal-microbe symbiotic systems and short-cut biological nitrogen removal technology for wastewater treatment. Related studies have shown that short-range bacteria and algae exhibit significant advantages in biomass production and resource recovery while ensuring pollutant degradation, especially in the treatment of wastewater with high ammonia nitrogen and low C / N ratio (Jianfeng Ye, Junyu Liang, Liang Wang, et al. Operation optimization of a photo-sequencing batch reactor for wastewater treatment: Study on influencing factors and impact on symbiotic microbialecology[J]. Bioresource Technology, 2018, 252: 7-13; Shunni Zhu, Lei Qin, Pingzhong Feng, et al. Treatment of low C / N ratio wastewater and biomass production using co-culture of Chlorella vulgaris and activated sludge in a batch photobioreactor[J]. Bioresource Technology, 2019, 274: 313-320). Currently, short-range microbial-algae treatment is mainly achieved through three pathways: SBR reactors, aerobic granular sludge, and membrane bioreactors. However, aerobic granular sludge often suffers from poor particle stability and easy disintegration, while membrane bioreactors require frequent cleaning to maintain treatment efficiency and typically face high operation and maintenance costs. Therefore, it is necessary to conduct research combining the start-up and stable maintenance of short-range microbial-algae systems and SBR reactors to provide a new approach for wastewater denitrification. Summary of the Invention

[0005] The purpose of this invention is to provide a device and method for deep denitrification of high ammonia nitrogen wastewater, based on in-situ algae and bacteria to rapidly establish a short-cut nitrification-denitrification enhanced AOA process. In this invention, domestic wastewater enters the anaerobic stage of an SBR reactor. Under anaerobic conditions, polyphosphate-accumulating bacteria absorb volatile fatty acids (VFAs) from the wastewater and convert them into polyhydroxyalkanoates (PHAs). Simultaneously, some nitrogenous organic matter undergoes ammonification under the action of bacteria. Subsequently, the wastewater enters the aerobic stage, accumulating a large amount of nitrite nitrogen through a short-cut nitrification process. Finally, it enters the anoxic stage, where nitrite nitrogen is reduced to nitrogen gas by denitrifying bacteria, achieving nitrogen removal. Since the photosynthesis of microalgae provides a large amount of oxygen for the nitrifying bacteria, the aeration requirement in this stage is significantly reduced compared to the traditional AOA process. Furthermore, the algal-derived organic matter secreted by the microalgae provides a carbon source for the denitrifying bacteria, reducing the need for external carbon source addition during the anoxic stage, thus simultaneously achieving the cultivation of short-cut in-situ algae and bacteria and the efficient removal of nitrogen and phosphorus.

[0006] A device for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae includes: an influent system 1, a peristaltic pump 2, a WTW main unit 3, a pH probe 4, a DO probe 5, a stirrer 6, a rotor flow meter 7, an air pump 8, an outlet valve 9, and an SBR reactor 10. Domestic sewage from the influent system 1 enters the SBR reactor 10 via the peristaltic pump 2. The SBR reactor 10 contains a short-cut in-situ bacteria and algae system and is also equipped with a pH probe 4, a DO probe 5, and a stirrer 6. The pH probe 4 and DO probe 5 are connected to the WTW main unit 3 via data cables. The stirrer 6 agitates the mixture of the short-cut in-situ bacteria and algae system and the domestic sewage. The air pump 8 is connected to the rotor flow meter 7 to aerate the mixture of the short-cut in-situ bacteria and algae system and the domestic sewage in the SBR reactor 10. An outlet valve 9 is installed on the side wall of the SBR reactor 10 for drainage.

[0007] A method for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae includes the following steps:

[0008] (1) The activated sludge in the reactor was acclimated using simulated wastewater with gradient ammonia nitrogen concentrations until the accumulation rate of nitrite nitrogen in the reactor was >90% and remained stable, thus obtaining a short-cut nitrification activated sludge system.

[0009] (2) Simulated wastewater containing ammonia nitrogen is introduced into the reactor, and the short-cut nitrification activated sludge system is simultaneously illuminated with a light density of 0.0188 to 0.0553 kJ / mgVSS. The pH is controlled at 7.0 to 7.5 throughout the process, and aeration is carried out to control dissolved oxygen at 2 to 3 mg / L. The system is cultivated until the reactor turns green to obtain a short-cut in-situ bacterial and algal system.

[0010] (3) The short-range in-situ bacteria and algae system is moved into the SBR reactor and domestic sewage is introduced. The reactor is operated in AOA mode to achieve deep denitrification.

[0011] Preferably, in step (1), after the ammonia nitrogen concentration in the effluent is lower than 15 mg / L in each stage, the next ammonia nitrogen concentration gradient is entered.

[0012] Preferably, in step (2), the short-cut nitrification activated sludge system is first centrifuged at 4000 rpm, and the supernatant is discarded after centrifugation to form a short-cut nitrification activated sludge system with a concentration of 3000-3500 mg / L.

[0013] Preferably, in step (2), aeration is performed by an air pump with an aeration stone.

[0014] Preferably, in step (2), the culture time is more than one month.

[0015] Preferably, in step (3), the AOA mode is as follows: each operating cycle is twelve hours, including 5 minutes of water intake, 60 minutes of anaerobic stirring, 480 minutes of aerobic aeration, 120 minutes of anoxic stirring, 50 minutes of sedimentation, 5 minutes of drainage, and the rest of the time is idle.

[0016] Compared with existing AOA processes, this invention has the following advantages:

[0017] (1) This invention successfully constructed a short-range in-situ bacterial-algal system through domestication. Based on the complementary metabolic functions of microalgae and bacteria, a good symbiotic relationship was formed, which significantly reduced the aeration amount in the aerobic stage and the amount of external carbon source added in the hypoxic stage.

[0018] (2) Compared with other short-range denitrification systems, this invention achieves flexible adjustment of DO and photoperiod in the mixed biological system through the SBR reactor, adapts to the needs of bacterial-algae symbiosis, realizes efficient synergy of short-range bacterial-algae system, and the average ammonia nitrogen removal rate is stable at over 90%.

[0019] In summary, this invention innovatively constructs a highly efficient nitrogen removal technology system by coupling a short-range in-situ bacterial-algal symbiotic system with the AOA process. Compared to traditional processes, this technology system demonstrates significant advantages in achieving stable reduction of ammonia nitrogen pollutants. By optimizing the synergistic metabolic pathway of bacteria and algae, it effectively reduces aeration energy consumption and the need for external carbon source addition, significantly lowering operating costs. This technology breaks through the dependence of traditional wastewater treatment technologies on fossil fuels, providing an innovative solution to the long-standing technical bottleneck of "high energy consumption and high emissions" in the industry. This low-carbon wastewater treatment model combines environmental and economic benefits, providing important technical support for the green transformation and upgrading of the industry. Attached Figure Description

[0020] Figure 1The diagram shows the structure of a device for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae. In the diagram: 1 is the influent system, 2 is the peristaltic pump, 3 is the WTW main unit, 4 is the pH probe, 5 is the DO probe, 6 is the agitator, 7 is the rotor flow meter, 8 is the air pump, 9 is the outlet valve, and 10 is the SBR reactor.

[0021] Figure 2 This is a schematic diagram of the reaction time of each stage in a cycle of the AOA operating mode. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0023] refer to Figure 1 A device for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae includes: an influent system 1, a peristaltic pump 2, a WTW main unit 3, a pH probe 4, a DO probe 5, a stirrer 6, a rotor flow meter 7, an air pump 8, an outlet valve 9, and an SBR reactor 10. Domestic sewage in the influent system 1 enters the SBR reactor 10 via the peristaltic pump 2. The SBR reactor 10 contains a short-cut in-situ bacteria and algae system and is also equipped with a pH probe 4, a DO probe 5, and a stirrer 6. The pH probe 4 and DO probe 5 are connected to the WTW main unit 3 via data cables. The stirrer 6 agitates the mixture of the short-cut in-situ bacteria and algae system and the domestic sewage. The air pump 8 is connected to the rotor flow meter 7 to aerate the mixture of the short-cut in-situ bacteria and algae system and the domestic sewage in the SBR reactor 10. An outlet valve 9 is installed on the side wall of the SBR reactor 10 for drainage.

[0024] Example 1

[0025] A method for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae is adopted. Figure 1 The device shown achieves deep denitrification of domestic sewage according to the following steps:

[0026] (1) The sludge was derived from nitrified flocculent sludge from a wastewater treatment plant. Simulated wastewater with gradient ammonia nitrogen concentrations was used to acclimate the sludge. After the effluent ammonia nitrogen concentration was lower than 15 mg / L at each stage, the next ammonia nitrogen concentration gradient was entered. The sludge was acclimatized until the nitrite nitrogen accumulation rate in the reactor was >90% and remained stable, thus obtaining a short-cut nitrification activated sludge system.

[0027] (2) The obtained short-cut nitrification activated sludge system was centrifuged at 4000 rpm. After centrifugation, the supernatant was discarded to obtain sludge with a concentration of 3000–3500 mg / L. The short-cut nitrification activated sludge system was then exposed to light at a density of 0.0188–0.0553 kJ / mgVSS. The pH was maintained at 7.0–7.5 throughout the process. Aeration was performed using an air pump equipped with aeration stones, and dissolved oxygen was maintained at 2–3 mg / L. After one month, the chlorophyll content in the reactor increased significantly, and a distinct green color was observed. Microscopic and electron microscopic observations showed that the short-cut in-situ bacterial-algal system was successfully cultivated.

[0028] (3) The short-range in-situ bacterial-algae system was transferred into the SBR reactor, and simulated wastewater containing ammonia nitrogen was introduced. The reactor operated in AOA mode, with each operating cycle lasting twelve hours, including 5 minutes of influent, 60 minutes of anaerobic stirring, 480 minutes of aerobic aeration, 120 minutes of anoxic stirring, 50 minutes of sedimentation, and 5 minutes of drainage, with the remaining time being idle.

[0029] Table 1 shows the composition of simulated wastewater containing ammonia nitrogen:

[0030]

[0031]

[0032] Table 2 shows the simulated wastewater influent indicators and the pollutant concentrations and removal rates in the reactor effluent.

[0033]

[0034] As shown in Table 1, the present invention provides a method for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae. The short-cut bacteria and algae system achieves deep removal of nitrogen from wastewater, promoting the application of in-situ bacteria and algae in actual wastewater treatment. It efficiently maintains short-cut nitrification, reduces carbon source consumption, and can be widely used for nitrogen removal in urban domestic wastewater.

Claims

1. A method for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae, characterized in that, An apparatus for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae includes the following steps: (1) The activated sludge in the reactor was acclimated using simulated wastewater with gradient ammonia nitrogen concentrations until the nitrite nitrogen accumulation rate in the reactor was >90% and remained stable, thus obtaining a short-cut nitrification activated sludge system. (2) Simulated wastewater containing ammonia nitrogen is introduced into the reactor, and the short-cut nitrification activated sludge system is simultaneously illuminated with a light density of 0.0188~0.0553 kJ / mgVSS. The pH is controlled at 7.0~7.5 throughout the process, and aeration is carried out to control dissolved oxygen at 2~3 mg / L. The system is cultivated until the reactor turns green to obtain a short-cut in-situ bacterial and algal system. (3) The short-range in-situ bacterial and algal system was moved into the SBR reactor and domestic sewage was introduced. The reactor was operated in AOA mode. The AOA mode is as follows: each operating cycle is twelve hours, including 5 min of water inlet, 60 min of anaerobic stirring, 480 min of aerobic aeration, 120 min of anoxic stirring, 50 min of sedimentation, 5 min of drainage, and the rest of the time is idle. The device for rapidly establishing a short-cut nitrification-denitrification enhanced AOA process for nitrogen removal based on in-situ bacteria and algae includes: an influent system (1), a peristaltic pump (2), a WTW main unit (3), a pH probe (4), a DO probe (5), a stirrer (6), a rotor flow meter (7), an air pump (8), an outlet valve (9), and an SBR reactor (10); the domestic sewage in the influent system (1) enters the SBR reactor (10) through the peristaltic pump 2; the SBR reactor (10) contains a short-cut in-situ bacteria and algae system, and is also equipped with a pH probe (4), a DO probe (5), and a stirrer (6), and the pH probe (4) and DO probe (5) are connected to the WTW main unit (3) through a data cable, the stirrer (6) stirs the mixed system composed of the short-cut in-situ bacteria and algae system and the domestic sewage, the air pump (8) is connected to the rotor flow meter (7) to aerate the mixed system composed of the short-cut in-situ bacteria and algae system and the domestic sewage in the SBR reactor (10), and an outlet valve (9) is set on the side wall of the SBR reactor (10) for drainage.

2. The method according to claim 1, characterized in that, In step (1), after the ammonia nitrogen concentration in the effluent is below 15 mg / L at each stage, the next ammonia nitrogen concentration gradient is entered.

3. The method according to claim 1, characterized in that, In step (2), the short-cut nitrification activated sludge system is first centrifuged at 4000 rpm, and the supernatant is discarded after centrifugation to form a short-cut nitrification activated sludge system with a concentration of 3000~3500 mg / L.

4. The method according to claim 1, characterized in that, In step (2), aeration is performed using an air pump with aeration stones.

5. The method according to claim 1, characterized in that, In step (2), the culture time is more than one month.

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