Activated sludge low-temperature biological denitrification strengthening method

Abstract

The invention discloses a method for enhancing low-temperature biological denitrification of activated sludge, which comprises the following steps: operating a traditional nitrification and denitrification activated sludge reactor at 15 DEG C for 30 days, supplementing a matrix according to inlet water, then transferring to 4 DEG C to stress for 30 days, and supplementing any matrix at the stage, finally, the reactor is continuously operated according to a traditional nitrification and denitrification mode under the condition that the temperature is recovered to 10-15 DEG C, the nitrification effect of the reactor can be improved by 30.31%, the total nitrogen removal rate is improved by 28.57%, and an efficient and stable regulation and control method is provided for improving activated sludge biological nitrogen removal at low temperature.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment, and in particular relates to an activated sludge low-temperature biological denitrification enhancement method. Background Art

[0002] Due to the differences in geographical regions in high latitudes and seasonal changes in winter / spring, wastewater temperature can often drop to 0~10℃. Low temperature seriously inhibits microbial activity, substrate utilization and cell growth, resulting in deterioration of wastewater treatment process performance and significantly reduced wastewater removal efficiency. Research on the treatment of low-temperature wastewater has gradually become a focus of increasing attention in the industry. Due to the inhibitory effect of low temperature on the activity of activated sludge microorganisms, the existing process is difficult to meet the treatment requirements of low-temperature wastewater in biochemical sewage plants under low temperature, and it is difficult to achieve standard discharge, which has a serious impact on the environmental load.

[0003] Due to the adverse effects of low temperature on the biochemical treatment of wastewater, Chinese water treatment workers have conducted some research on the biochemical treatment of low-temperature wastewater in recent years. In order to solve the problem of low-temperature wastewater being difficult to biodegrade, bio-enhanced treatment technology has been used in wastewater treatment to a certain extent. Tang Zixia et al. found that compared with the BAF system of expanded clay filler, expanded clay-bamboo fiber composite filler is suitable for microbial attachment. Under low temperature conditions, the co-degradation and synergistic degradation between different bacterial species on the composite filler are more significant, and the degradation effect on pollutants in the reaction system is more significant. Zhang Qi et al. studied the treatment of residential wastewater by combining magnetic separation and assembled artificial wetlands under low temperature conditions and found that the combined process had a good treatment effect on pollutants in residential wastewater, including COD, NH 4 + -N, TP removal rates were 86.8%, 52.5%, and 96.8%, respectively. Zhang Xiaofei et al. studied the removal effect of multi-stage AO-membrane bioreactor (MAO-MBR) process on organic matter, N, and P in municipal wastewater at low temperature (7~13℃) and found that the effluent COD, NH 4 + The average removal rates of -N are 97% and 98% respectively. After combined process treatment, the effluent quality meets the Class A standard of the Pollutant Discharge Standard for Urban Wastewater Treatment Plants (GB18918-2002).

[0004] Low temperature has become the biggest limiting factor for wastewater biological treatment processes in cold regions of China in winter. Due to the inhibitory effect of low temperature on the activity of activated sludge microorganisms, it is difficult for existing processes to meet the treatment requirements of low-temperature wastewater using traditional activated sludge sewage treatment plants, and it is difficult to achieve standard discharge. Among them, granular sludge is widely used to treat low-temperature wastewater, but the cultivation cycle of granular sludge is long, requires a higher operating temperature, and the cultivation process is relatively complicated. It is often necessary to connect aerobic biological treatment technology in series to ensure the stability of effluent quality and standard discharge of effluent. Magnetic field enhancement technology has become a research hotspot in the field of water treatment due to its advantages such as effective pollutant degradation rate, no secondary pollution, and low energy consumption. It provides new ideas, research directions and theoretical guidance for solving the problem of low-temperature printing and dyeing wastewater treatment. The composite control technology of magnetic field enhancement and sewage treatment has become a new process that is gradually emerging in the field of sewage treatment, but there is little theoretical research content in this field.

[0005] Research in the field of sewage treatment technology has been extensive, but the application of low-temperature wastewater treatment technology still faces great challenges. In addition, in the biological treatment of low-temperature wastewater, the removal of pollutants from low-temperature wastewater by microorganisms depends entirely on the metabolism of activated sludge microorganisms. Therefore, temperature, as an important ecological factor affecting the growth, reproduction and metabolic activity of microbial flora, has an important influence on the biological treatment of wastewater. In addition to adjusting the operating parameters of the traditional activated sludge system, such as reducing the load, increasing the hydraulic retention time, and taking certain insulation measures, there are mainly chemical enhanced coagulation, artificial wetland enhancement, and the addition of high-efficiency cold-resistant bacteria technology to enhance the treatment effect of low-temperature sewage. Liu Hailong et al. used a synthetic new composite coagulant (SynthA) to enhance coagulation under low temperature (2~5℃) conditions to study the removal of dissolved organic matter and found that enhanced coagulation can improve the system's removal effect on pollutants to a certain extent. Wei Zuohong et al. prepared modified nano-degradable methylene blue dye wastewater at low temperature and achieved good treatment results. Wu Haiquan et al. screened and cultivated microbial strains that can efficiently treat low-temperature urban sewage, enhance the cold resistance of activated sludge, and then enhance the treatment of low-temperature urban sewage.

[0006] Research on improving the efficiency of low-temperature biological wastewater treatment has focused on the acclimation or bio-augmentation of cold-adapted bacteria. There are still problems. In many areas, the temperature changes seasonally. Whether the dominant bacterial community adapted to low temperatures will remain stable and genetically stable during long-term temperature cycles is still controversial. In addition, the current treatment process measures have certain shortcomings and deficiencies, which not only increase engineering investment and operating costs, but also cannot guarantee the cold shock resistance in complex and changeable low-temperature environments, and often cause sludge bulking and other problems.

[0007] Since temperature plays a decisive role in the growth, reproduction, metabolism, biological population distribution and population size of activated sludge microorganisms, it directly affects the efficiency of winter sewage treatment, and the treatment effect of sewage treatment plants with biochemical methods as the main process is seriously affected. Therefore, low temperature has become the biggest limiting factor for wastewater biological treatment processes in cold areas of China in winter, making low-temperature (0~10℃) wastewater treatment a major problem currently faced by the field of environmental water treatment. Therefore, it is necessary to further explore the domestication or bioaugmentation of cold-adapted bacteria for the enhanced treatment of low-temperature wastewater by activated sludge, so as to provide theoretical guidance for further research on the treatment of low-temperature wastewater by activated sludge. Summary of the invention

[0008] The purpose of the present invention is to provide an activated sludge low-temperature biological denitrification enhancement method, find a suitable way to improve the ammonia nitrogen and total nitrogen removal rates of activated sludge at low temperatures, use cold stimulation to cause environmental stress to the activated sludge system, induce the succession of the microbial community structure, change the functional activity of microbial extracellular enzymes, and regulate the metabolic mechanism of microorganisms.

[0009] The purpose of the present invention is achieved through the following technical solutions: An activated sludge low-temperature biological denitrification enhancement method comprises the following steps: The activated sludge reactor was operated at 15°C for 30 days; Supplement the influent matrix; The activated sludge reactor was stored at 4°C for 30 days; The activated sludge reactor was operated at 10-15°C for 30 days.

[0010] Most patent applications involve numerical values. It is best not to write point values. As a more optimal technical solution of the present invention, the activated sludge reactor is a sequencing batch activated sludge reactor.

[0011] As a more optimal 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.

[0012] As a more optimal technical solution of the present invention, glucose (150 mg / L COD) is added to supplement denitrification when the activated sludge reactor operates for 7 hours in the aerobic aeration stage.

[0013] As a more optimal technical solution of the present invention, the influent matrix of the wastewater in the activated sludge reactor contains 30 mg / L NH 4 + -N and 100mg / L COD, pH 7.5-8.5.

[0014] As a more optimal technical solution of the present invention, the activated sludge reactor is operated at 15°C for 30 days; the influent matrix is ​​supplemented; 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.

[0015] Compared with the existing technology, it has the following advantages and effects: The temperature combination provided by the present invention can enhance the ammonia oxidation and nitrogen conversion activity of activated sludge under the condition of 10-15°C, so that the reactor can achieve better denitrification effect. A temperature combination stress method is used to achieve an unexpected low-temperature biological denitrification enhancement effect. Starting from the regulation of microbial community composition, extracellular enzyme activity, and microbial metabolic mechanism, the enhancement effect of low-temperature biological denitrification is fundamentally achieved, so that the effluent water quality meets the Class A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB18918-2002). Energy-saving and efficient, compared with traditional means of enhancing low-temperature biological denitrification, it reduces electricity consumption and drug consumption. After cold stimulation, the ammonia nitrogen and total nitrogen removal rates of the activated sludge reactor can be continuously and stably maintained at more than 80% and 90%, achieving stable operation for up to 30 days.

[0016] The method provided by the present invention is efficient, energy-saving and stable, and is beneficial to enhancing the biological deammoniation effect of low-temperature actual sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the water quality monitoring data chart for the three stages of long-term operation of the activated sludge reactor; Figure 2 This is the single-cycle water quality monitoring data of the activated sludge reactor before low-temperature stimulation; Figure 3 This is the single-cycle water quality monitoring data of the activated sludge reactor after low-temperature stimulation; Figure 4 This is the specific ammonia oxidation rate diagram of the activated sludge reactor before and after low temperature stimulation; Figure 5 This is a graph showing the total nitrogen removal rate of the activated sludge reactor before and after low temperature stimulation. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with embodiments, but is not intended to limit the present invention thereto.

[0019] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0020] The sequencing batch reactor (SBR) used in this example has an effective volume of 10 L, an initial sludge concentration of about 5144 mg / L, and a sludge concentration of about 4988 mg / L after treatment. A stirring device is installed on the top of the reactor to ensure uniform mixing of mud and water, and an aeration device is installed at the bottom to ensure aerobic conditions in the system. The DO concentration in the water at the three stages is greater than 2 mg / L. The test water is artificial synthetic wastewater, and the influent matrix contains 30 mg / L NH 4 + -N and 100 mg / L COD, pH 7.5-8.5.

[0021] Comparative Example The activated sludge low-temperature biological denitrification enhancement method of this embodiment comprises the following steps: The reactor was operated at 15℃, with an aeration rate of 750mL / min. Each operation cycle of the SBR reactor was 11 hours. After 0.5 hours of water inflow and 7 hours of aerobic aeration and stirring, the aeration device was turned off, glucose (150mg / L COD) was added, and anoxic stirring was continued for 2 hours, sedimentation for 1 hour, and drainage for 0.5 hours. The drainage ratio of each cycle was 50%. After 30 days of operation in this stage, the influent substrate was added and stored for 30 days. No substrate was added in this stage and it was operated for another 30 days.

[0022] The removal rate of ammonia nitrogen in the comparative example is 62.46%, and the removal rate of ammonia nitrogen is 81.38%.

[0023] Example 1 The activated sludge low-temperature biological denitrification enhancement method of this embodiment comprises the following steps: The reactor was operated at 15°C with an aeration rate of 750 mL / min. Each operation cycle of the SBR reactor was 11 hours. After 0.5 hours of water inflow and 7 hours of aerobic aeration and stirring, the aeration device was turned off, glucose (COD 150 mg / L) was added, and anoxic stirring was continued for 2 hours, sedimentation for 1 hour, and drainage for 0.5 hours. The drainage ratio of each cycle was 50%. After 30 days of operation in this stage, the influent substrate was supplemented and the reactor was transferred to 4°C for storage for 30 days. No substrate was added during this stage. Finally, it was switched back to 15°C for operation for 30 days. The operating conditions of the SBR reactor were the same as before the storage at 4°C.

[0024] Compared with the water quality data of the comparative example using the method of this embodiment 1, the ammonia nitrogen removal rate is increased by 30.31%, and the total nitrogen removal rate is increased by 28.57%. This embodiment successfully improves the denitrification efficiency of low-temperature activated sludge.

[0025] like Figure 1 As shown, the total inorganic nitrogen removal rate of the method provided in this embodiment is improved, and the ammonia nitrogen in the effluent after cold stimulation is significantly reduced compared with the ammonia nitrogen in the effluent before stimulation.

[0026] like Figure 2 and Figure 3 As shown, the method provided in this embodiment is based on low temperature stress to change the bacterial community structure and microbial metabolic activity to enhance the low temperature biological denitrification effect, and the environmental stress method is used to achieve the enhancement.

[0027] like Figure 4 and Figure 5 As shown in the figure, the specific ammonia oxidation activity and the specific total nitrogen removal rate were significantly improved after low-temperature stimulation. By operating normally first, then cold stimulation, and then normal operation, the succession of the community structure in the activated sludge system was induced, the extracellular enzyme activity and stability 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 under low temperature and improved the efficiency of low-temperature sewage treatment.

[0028] Example 2 The activated sludge low temperature biological denitrification enhancement method of this embodiment is different from that of embodiment 1 only in that: The reactor was operated at 15°C with an aeration rate of 750 mL / min. Each operation cycle of the SBR reactor was 11 hours. After 0.5 hours of water inflow and 7 hours of aerobic aeration and stirring, the aeration device was turned off, glucose (COD 150 mg / L) was added, and anoxic stirring was continued for 2 hours, sedimentation for 1 hour, and drainage for 0.5 hours. The drainage ratio of each cycle was 50%. After 30 days of operation in this stage, the influent substrate was supplemented and the reactor was transferred to 4°C for storage for 30 days. No substrate was added during this stage. Finally, the reactor was transferred to 10°C for operation for 30 days. The operating conditions of the SBR reactor were the same as before the storage at 4°C.

[0029] Example 3 The activated sludge low temperature biological denitrification enhancement method of this embodiment is different from that of embodiment 1 only in that: The reactor was operated at 5°C with an aeration rate of 750 mL / min. Each operation cycle of the SBR reactor was 11 hours. After 0.5 hours of water inflow and 7 hours of aerobic aeration and stirring, the aeration device was turned off, glucose (COD 150 mg / L) was added, and anoxic stirring was continued for 2 hours, sedimentation for 1 hour, and drainage for 0.5 hours. The drainage ratio of each cycle was 50%. After 30 days of operation in this stage, the influent substrate was supplemented and the reactor was transferred to 4°C for storage for 30 days. No substrate was added during this stage. Finally, the reactor was transferred to 15°C for operation for 30 days. The operating conditions of the SBR reactor were the same as before the storage at 4°C.

[0030] Example 4 The activated sludge low temperature biological denitrification enhancement method of this embodiment is different from that of embodiment 1 only in that: The reactor was operated at 15°C with an aeration rate of 750 mL / min. Each operation cycle of the SBR reactor was 11 hours. After 0.5 hours of water inflow and 7 hours of aerobic aeration and stirring, the aeration device was turned off, glucose (COD 150 mg / L) was added, and anoxic stirring was continued for 2 hours, sedimentation for 1 hour, and drainage for 0.5 hours. The drainage ratio of each cycle was 50%. After 30 days of operation in this stage, the influent substrate was supplemented and the reactor was transferred to 4°C for storage for 30 days. No substrate was added during this stage. Finally, the reactor was transferred to 5°C for operation for 30 days. The operating conditions of the SBR reactor were the same as before the storage at 4°C.

[0031] Example 5 The activated sludge low temperature biological denitrification enhancement method of this embodiment is different from that of embodiment 1 only in that: The reactor was operated at 15°C with an aeration rate of 750 mL / min. Each operation cycle of the SBR reactor was 11 hours. After 0.5 hours of water inflow and 7 hours of aerobic aeration and stirring, the aeration device was turned off, glucose (COD 150 mg / L) was added, and anoxic stirring was continued for 2 hours, sedimentation for 1 hour, and drainage for 0.5 hours. The drainage ratio of each cycle was 50%. After 30 days of operation in this stage, the influent substrate was supplemented and the reactor was transferred to 8°C for storage for 30 days. No substrate was added during this stage. Finally, the reactor was transferred to 15°C for operation for 30 days. The operating conditions of the SBR reactor were the same as before the storage at 4°C.

[0032] Example 6 The activated sludge low temperature biological denitrification enhancement method of this embodiment is different from that of embodiment 1 only in that: The reactor was operated at 15°C with an aeration rate of 750 mL / min. Each operation cycle of the SBR reactor was 11 hours. After 0.5 hours of water inflow and 7 hours of aerobic aeration and stirring, the aeration device was turned off, glucose (COD 150 mg / L) was added, and anoxic stirring was continued for 2 hours, sedimentation for 1 hour, and drainage for 0.5 hours. The drainage ratio of each cycle was 50%. After 30 days of operation in this stage, the influent substrate was supplemented and the reactor was transferred to 1°C for storage for 30 days. No substrate was added during this stage. Finally, the reactor was transferred to 15°C for operation for 30 days. The operating conditions of the SBR reactor were the same as before the storage at 4°C.

[0033] The processing data of the above embodiment is compared with the comparative embodiment as shown in the following table: Compared with the water quality data of the comparative example using the method of this embodiment, the maximum ammonia nitrogen removal rate increased by 30.31%, and the maximum total nitrogen removal rate increased by 28.57%, successfully improving the denitrification efficiency of low-temperature activated sludge.

[0034] In the present invention, sludge concentration refers to the content of suspended solids in the mixed liquor after sewage and activated sludge are mixed.

[0035] The implementation methods of the present invention are not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention. Although the embodiments of the present invention have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above-mentioned embodiments within the scope of the present invention.

Claims

1. An activated sludge low-temperature biological denitrification enhancement method, characterized in that: The steps include: The activated sludge reactor was operated at 15°C for 30 days; Supplement the influent matrix; The activated sludge reactor was stored at 4°C for 30 days; The activated sludge reactor was operated at 10-15°C for 30 days.

2. The activated sludge low-temperature biological denitrification enhancement method according to claim 1, characterized in that: The activated sludge reactor is a sequencing batch activated sludge reactor.

3. The activated sludge low-temperature biological denitrification enhancement method according to claim 1, characterized in that: The activated sludge reactor maintains dissolved oxygen above 2 mg / L during the aerobic aeration stage.

4. The activated sludge low-temperature biological denitrification enhancement method according to claim 1, characterized in that: When the operating time of the activated sludge reactor in the aerobic aeration stage is 7 hours, glucose is added to supplement denitrification.

5. The activated sludge low-temperature biological denitrification enhancement method according to claim 1, characterized in that: The influent matrix of the wastewater in the activated sludge reactor contains 30 mg / L NH4 + -N and 100mg / L COD, pH 7.5-8.

5.

6. The activated sludge low-temperature biological denitrification enhancement method according to claim 1, characterized in that: The activated sludge reactor was operated at 15°C for 30 days; the influent substrate was supplemented; the activated sludge reactor was stored at 4°C for 30 days; and the activated sludge reactor was operated at 15°C for 30 days.

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