A method for enhancing low-temperature biological denitrification of activated sludge

Abstract

The application discloses a kind of activated sludge low-temperature biological denitrification reinforcement methods, in 15 ℃ condition, traditional nitrification denitrification activated sludge reactor is operated for 30 days, after water is supplied to substrate, it is changed to 4 ℃ condition and stressed for 30 days, any substrate is supplemented in this stage, finally, it is restored to 10-15 ℃ condition, and the reactor is continued to be operated according to traditional nitrification denitrification mode, can the nitrification effect of reactor is improved by 30.31%, total nitrogen removal rate is increased by 28.57%, provides a kind of efficient and stable regulation method for improving activated sludge biological denitrification under low temperature.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, specifically relating to a method for enhancing low-temperature biological nitrogen removal from activated sludge. Background Technology

[0002] Due to geographical differences in high-latitude regions and seasonal variations during winter / spring, wastewater temperatures can often drop to 0-10℃. Low temperatures severely inhibit microbial activity, substrate utilization, and cell growth, leading to deterioration of wastewater treatment process performance and a significant reduction in wastewater removal efficiency. Research on the treatment of low-temperature wastewater has gradually become a focus of increasing attention within the industry. Because of the inhibitory effect of low temperatures on the activity of activated sludge microorganisms, existing processes are insufficient to meet the treatment requirements of low-temperature wastewater from biological wastewater treatment plants, and achieving compliant discharge is difficult, resulting in a serious impact on the environment.

[0003] Due to the adverse effects of low temperatures on the biochemical treatment of wastewater, Chinese water treatment researchers have conducted some research on low-temperature wastewater biochemical treatment in recent years. To address the problem of the difficulty in biodegrading low-temperature wastewater, bio-enhanced treatment technology has been applied to some extent in wastewater treatment. Tang Zixia et al. found that compared with the BAF system using ceramsite packing, ceramsite-bamboo composite packing is more suitable for microbial attachment. Under low-temperature conditions, the co-degradation and synergistic degradation effects among different bacterial species on the composite packing are more significant, resulting in a more significant degradation effect on pollutants within the reaction system. Zhang Qi et al., in their study on the treatment of residential wastewater using a combination of magnetic separation and prefabricated constructed wetlands under low-temperature conditions, found that this combined process has a good treatment effect on pollutants in the wastewater, including COD and NH4+. + The removal rates of -N and TP were 86.8%, 52.5%, and 96.8%, respectively. Zhang Xiaofei et al., in their study of the removal efficiency of organic matter, N, and P from municipal wastewater using a multi-stage AO-membrane bioreactor (MAO-MBR) process at low temperatures (7~13℃), found that the effluent COD and NH4+ levels were significantly reduced. + The average removal rates of -N were 97% and 98%, respectively. After treatment by the combined process, the effluent quality met the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002).

[0004] Low temperature has become the biggest limiting factor for biological wastewater treatment processes in cold winter regions of China. Due to the inhibitory effect of low temperature on the activity of activated sludge microorganisms, existing processes struggle to meet the treatment requirements of traditional activated sludge wastewater treatment plants for low-temperature wastewater, making it difficult to achieve compliant discharge. Granular sludge is widely used for treating low-temperature wastewater, but its cultivation cycle is long, requiring high operating temperatures and a complex process. It often necessitates the use of aerobic biological treatment technologies in conjunction with granular sludge to ensure stable effluent quality and compliance with discharge standards. Magnetic field enhancement technology, with its advantages of high pollutant degradation rates, no secondary pollution, and low energy consumption, has become a research hotspot in the water treatment field. It provides new ideas, research directions, and theoretical guidance for solving the problem of low-temperature dyeing and printing wastewater treatment. The combined control technology of magnetic field enhancement and wastewater treatment has become a gradually emerging new process in wastewater treatment, but theoretical research in this area is limited.

[0005] Research in wastewater treatment technology is relatively extensive, but the application of low-temperature wastewater treatment technology still faces significant challenges. Furthermore, in the biological treatment of low-temperature wastewater, the removal of pollutants by microorganisms depends entirely on the metabolism of activated sludge microorganisms. Therefore, temperature, as a crucial ecological factor affecting the growth, reproduction, and metabolic activity of microbial communities, has a significant impact on wastewater biological treatment. Besides adjusting the operating parameters of traditional activated sludge systems, such as reducing load, increasing hydraulic retention time, and implementing insulation measures, the main methods to enhance the treatment effect of low-temperature wastewater include chemically enhanced coagulation, constructed wetland enhancement, and the addition of highly efficient, cold-resistant bacterial strains. Liu Hailong et al., in their research on enhancing coagulation at low temperatures (2-5℃) to remove dissolved organic matter using a novel synthetic composite coagulant (SynthA), found that enhanced coagulation can improve the system's pollutant removal efficiency to a certain extent. Wei Zuohong et al. achieved good treatment results in the low-temperature preparation of modified nano-degradable methylene blue dye wastewater. Wu Haiquan et al. screened and cultivated highly efficient microbial strains for treating low-temperature urban wastewater, enhancing the cold resistance of activated sludge and thus strengthening the treatment of low-temperature urban wastewater.

[0006] Research on improving the efficiency of low-temperature biological wastewater treatment has focused on the domestication or bioaugmentation of cold-adapted bacteria. However, challenges remain, as temperatures vary seasonally in many regions. Whether dominant bacterial communities will remain stable under low temperatures and whether they will be genetically inherited during long-term temperature cycles remains controversial. Furthermore, current treatment processes have certain drawbacks and limitations, not only increasing engineering investment and operating costs but also failing to guarantee resistance to cold shocks in complex and variable low-temperature environments, often leading to problems such as sludge bulking.

[0007] Temperature plays a decisive role in the growth, reproduction, metabolism, population distribution, and size of activated sludge microorganisms, directly affecting the efficiency of wastewater treatment in winter. Wastewater treatment plants using biochemical methods as their primary process are severely impacted. Therefore, low temperature is the biggest limiting factor for biological wastewater treatment processes in cold winter regions of China, making low-temperature (0-10℃) wastewater treatment a major challenge in the environmental water treatment field. Further research is needed on the domestication or bioaugmentation of cold-adapted bacteria to enhance activated sludge treatment of low-temperature wastewater, providing theoretical guidance for further research on activated sludge treatment of low-temperature wastewater. Summary of the Invention

[0008] The purpose of this invention is to provide a method for enhancing low-temperature biological nitrogen removal from activated sludge, discovering a suitable way to improve the removal rate of ammonia nitrogen and total nitrogen from activated sludge at low temperatures, using cold stimulation to create environmental stress on the activated sludge system, inducing the succession of microbial community structure, changing the functional activity of extracellular enzymes of microorganisms, and regulating the metabolic mechanism of microorganisms.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for enhancing low-temperature biological nitrogen removal from activated sludge includes the following steps:

[0011] The activated sludge reactor was operated at 15°C for 30 days.

[0012] Replenish the influent substrate;

[0013] The activated sludge reactor was stored at 4°C for 30 days.

[0014] The activated sludge reactor was operated at 10-15℃ for 30 days.

[0015] Most patent applications involve numerical values; it's best to avoid including numerical values.

[0016] As a preferred technical solution of the present invention, the activated sludge reactor is a sequencing batch reactor.

[0017] As a preferred technical solution of the present invention, the dissolved oxygen in the activated sludge reactor is maintained above 2 mg / L during the aerobic aeration stage.

[0018] As a preferred technical solution of the present invention, glucose (150 mg / L COD) is added to the activated sludge reactor during the aerobic aeration stage when the reactor operates for 7 hours.

[0019] As a preferred embodiment of the present invention, the influent substrate of the activated sludge reactor contains 30 mg / L of NH4. +-N and 100 mg / L COD, pH 7.5-8.5.

[0020] As a preferred technical solution of the present invention, the activated sludge reactor is operated at 15°C for 30 days; the influent substrate is replenished; the activated sludge reactor is stored at 4°C for 30 days; and the activated sludge reactor is operated at 15°C for 30 days.

[0021] Compared to existing technologies, it has the following advantages and effects:

[0022] The temperature combination provided by this invention can enhance the ammonia oxidation and nitrogen conversion activities of activated sludge at 10-15℃, thereby achieving better denitrification in the reactor. An unexpectedly enhanced low-temperature biological denitrification effect is achieved through a temperature stress method. By regulating the microbial community composition, extracellular enzyme activity, and microbial metabolic mechanisms, the enhanced low-temperature biological denitrification effect is fundamentally realized, ensuring that the effluent quality meets the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002). It is energy-efficient and highly effective, reducing power and chemical consumption compared to traditional methods of enhancing low-temperature biological denitrification. After cold stimulation, the ammonia nitrogen and total nitrogen removal rates of the activated sludge reactor can remain stable at over 80% and 90%, respectively, achieving stable operation for up to 30 days.

[0023] The method provided by this invention is efficient, energy-saving, and stable, which is beneficial for enhancing the biological ammonia removal effect in actual low-temperature wastewater treatment. Attached Figure Description

[0024] Figure 1 A graph showing long-term water quality monitoring data for three stages of activated sludge reactor operation;

[0025] Figure 2 This is a graph showing water quality monitoring data for a single cycle of an activated sludge reactor before low-temperature stimulation.

[0026] Figure 3 This is a graph showing the water quality monitoring data of a single cycle in an activated sludge reactor after low-temperature stimulation.

[0027] Figure 4 The graph shows the specific ammonia oxidation rate of the activated sludge reactor before and after low-temperature stimulation.

[0028] Figure 5 The graph shows the total nitrogen removal rate of the activated sludge reactor before and after low-temperature stimulation. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments, but it is not intended to limit the present invention.

[0030] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0031] The sequencing batch reactor (SBR) used in this embodiment has an effective volume of 10 L. The initial sludge concentration (MLSS) was approximately 5144 mg / L, and the treated sludge concentration (MLSS) was approximately 4988 mg / L. A stirring device was installed at the top of the reactor to ensure uniform mixing of the sludge and water, and an aeration device was installed at the bottom to ensure aerobic conditions in the system. The dissolved oxygen (DO) concentration in the water was greater than 2 mg / L in all three stages. Synthetic wastewater was used as the test water, and the influent substrate contained 30 mg / L of NH4+. + -N and 100 mg / L COD, pH 7.5-8.5.

[0032] Comparative Examples

[0033] The activated sludge low-temperature biological nitrogen removal enhancement method of this embodiment includes the following steps:

[0034] The SBR reactor operates at 15℃ with an aeration rate of 750 mL / min, and each operating cycle is 11 hours. After 0.5 hours of influent, aerobic aeration and stirring are performed for 7 hours. Then, the aeration device is shut off, glucose (150 mg / L COD) is added, and the reactor continues to be anoxically agitated for 2 hours, followed by sedimentation for 1 hour, and then 0.5 hours of drainage. The drainage ratio for each cycle is 50%. This stage is run for 30 days. After this period, influent substrate is added and stored for 30 days. No substrate is added during this stage, and the reactor is then run for another 30 days.

[0035] The ammonia nitrogen removal rate in the comparative example was 62.46%, while the ammonia nitrogen removal rate was 81.38%.

[0036] Example 1

[0037] The activated sludge low-temperature biological nitrogen removal enhancement method of this embodiment includes the following steps:

[0038] The SBR reactor was operated at 15℃ with an aeration rate of 750 mL / min, and each operating cycle was 11 hours. After 0.5 hours of influent, aerobic aeration and stirring were performed for 7 hours, at which point the aeration device was shut off. Glucose (COD 150 mg / L) was added, and the reactor continued to be anoxically agitated for 2 hours, followed by sedimentation for 1 hour and 0.5 hours of effluent discharge. The effluent discharge ratio was 50% per cycle. After 30 days of this stage, influent substrate was added, and the reactor was transferred to 4℃ for storage for 30 days without any additional substrate. Finally, the reactor was returned to 15℃ for 30 days, with the operating conditions identical to those before the 4℃ storage.

[0039] Compared with the comparative example, the water quality data using the method of Example 1 showed that the ammonia nitrogen removal rate increased by 30.31% and the total nitrogen removal rate increased by 28.57%. This example successfully improved the denitrification efficiency of low-temperature activated sludge.

[0040] like Figure 1 As shown, the method provided in this embodiment improves the total inorganic nitrogen removal rate, and the ammonia nitrogen in the effluent after cold stimulation is significantly reduced compared to the ammonia nitrogen in the effluent before stimulation.

[0041] like Figure 2 and Figure 3 As shown in the figure, the method provided in this embodiment for enhancing the effect of low-temperature biological denitrification by altering the microbial community structure and microbial metabolic activity under low-temperature stress is achieved by using environmental stress methods.

[0042] like Figure 4 and Figure 5 As shown, the specific ammonia oxidation activity and specific total nitrogen removal rate were significantly improved after low-temperature stimulation. By inducing the succession of the community structure in the activated sludge system through normal operation, cold stimulation, and then normal operation again, the activity and stability of extracellular enzymes were changed, the metabolic mechanism of microorganisms was regulated, and the low-temperature ammonia oxidation activity and nitrogen conversion activity of microorganisms were enhanced, which fundamentally improved the biological denitrification effect at low temperature and improved the efficiency of low-temperature wastewater treatment.

[0043] Example 2

[0044] The difference between the activated sludge low-temperature biological nitrogen removal enhancement method in this embodiment and Example 1 is only that:

[0045] The SBR reactor was operated at 15℃ with an aeration rate of 750 mL / min, and each operating cycle was 11 hours. After 0.5 hours of influent, aerobic aeration and stirring were performed for 7 hours, at which point the aeration device was shut off. Glucose (COD 150 mg / L) was added, and the reactor continued to be anoxically agitated for 2 hours, followed by 1 hour of sedimentation and 0.5 hours of effluent discharge. The effluent discharge ratio was 50% per cycle. After 30 days of this stage, influent substrate was added, and the reactor was transferred to 4℃ for storage for 30 days without any additional substrate. Finally, the reactor was operated at 10℃ for 30 days, maintaining the same operating conditions as before the 4℃ storage.

[0046] Example 3

[0047] The difference between the activated sludge low-temperature biological nitrogen removal enhancement method in this embodiment and Example 1 is only that:

[0048] The SBR reactor was operated at 5℃ with an aeration rate of 750 mL / min, and each operating cycle was 11 hours. After 0.5 hours of influent, aerobic aeration and stirring were performed for 7 hours, after which the aeration device was shut off. Glucose (COD 150 mg / L) was added, and anoxic stirring continued for 2 hours, followed by 1 hour of sedimentation and 0.5 hours of effluent discharge. The effluent discharge ratio was 50% per cycle. After 30 days of this stage, influent substrate was added, and the reactor was transferred to 4℃ for storage for 30 days without any additional substrate. Finally, the reactor was operated at 15℃ for 30 days, maintaining the same operating conditions as before the 4℃ storage.

[0049] Example 4

[0050] The difference between the activated sludge low-temperature biological nitrogen removal enhancement method in this embodiment and Example 1 is only that:

[0051] The SBR reactor was operated at 15℃ with an aeration rate of 750 mL / min, and each operating cycle was 11 hours. After 0.5 hours of influent, aerobic aeration and stirring were performed for 7 hours, after which the aeration device was shut off. Glucose (COD 150 mg / L) was added, and anoxic stirring continued for 2 hours, followed by 1 hour of sedimentation and 0.5 hours of effluent discharge. The effluent discharge ratio was 50% per cycle. After 30 days of this stage, influent substrate was added, and the reactor was transferred to 4℃ for storage for 30 days without any additional substrate. Finally, the reactor was operated at 5℃ for 30 days, maintaining the same operating conditions as before the 4℃ storage.

[0052] Example 5

[0053] The difference between the activated sludge low-temperature biological nitrogen removal enhancement method in this embodiment and Example 1 is only that:

[0054] The SBR reactor was operated at 15℃ with an aeration rate of 750 mL / min, and each operating cycle was 11 hours. After 0.5 hours of influent, aerobic aeration and stirring were performed for 7 hours, at which point the aeration device was shut off. Glucose (COD 150 mg / L) was added, and the reactor continued to be anoxically agitated for 2 hours, followed by 1 hour of sedimentation and 0.5 hours of effluent discharge. The effluent discharge ratio was 50% per cycle. After 30 days of this stage, influent substrate was added, and the reactor was transferred to 8℃ for storage for 30 days without any additional substrate. Finally, the reactor was operated at 15℃ for 30 days, maintaining the same operating conditions as before storage at 4℃.

[0055] Example 6

[0056] The difference between the activated sludge low-temperature biological nitrogen removal enhancement method in this embodiment and Example 1 is only that:

[0057] The SBR reactor was operated at 15℃ with an aeration rate of 750 mL / min, and each operating cycle was 11 hours. After 0.5 hours of influent, aerobic aeration and stirring were performed for 7 hours, at which point the aeration device was shut off. Glucose (COD 150 mg / L) was added, and anoxic stirring continued for 2 hours, followed by 1 hour of sedimentation and 0.5 hours of effluent discharge. The effluent discharge ratio was 50% per cycle. After 30 days of this stage, influent substrate was added, and the reactor was stored at 1℃ for 30 days without any additional substrate. Finally, the reactor was operated at 15℃ for 30 days, maintaining the same operating conditions as before storage at 4℃.

[0058] The data processed in the above embodiments are compared with those in the comparative embodiments in the following table:

[0059] Compared with the comparative example, the water quality data using the method of this embodiment showed that the highest ammonia nitrogen removal rate increased by 30.31% and the highest total nitrogen removal rate increased by 28.57%, successfully improving the denitrification efficiency of low-temperature activated sludge.

[0060]

[0061] In this invention, sludge concentration refers to the suspended solids content of the mixture after wastewater and activated sludge are mixed.

[0062] The embodiments of the present invention are not limited to the above-described examples. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the scope of protection of the present invention. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for enhancing low-temperature biological nitrogen removal from activated sludge, characterized in that, Includes the following steps: The activated sludge reactor was operated at 15°C for 30 days. Replenish the influent substrate; The activated sludge reactor was stored at 4°C for 30 days. The activated sludge reactor was operated at 10-15℃ for 30 days; The activated sludge reactor is a sequencing batch reactor (SBR). The dissolved oxygen in the activated sludge reactor is maintained above 2 mg / L during the aerobic aeration stage; glucose is added to supplement denitrification during the 7-hour aerobic aeration stage of the activated sludge reactor; the influent substrate of the wastewater in the activated sludge reactor contains 30 mg / L of NH4. + -N and 100 mg / L COD, pH 7.5-8.

5.

2. The method for enhancing low-temperature biological nitrogen removal from activated sludge as described in claim 1, characterized in that, The activated sludge reactor was operated at 15°C for 30 days; influent substrate was added; the activated sludge reactor was stored at 4°C for 30 days; the activated sludge reactor was then operated at 15°C for 30 days.

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