Method for improving anaerobic ammonia oxidation denitrification efficiency based on variable temperature regulation and control

Abstract

The invention discloses a method for improving anaerobic ammonia oxidation denitrification efficiency based on variable temperature regulation and control. According to the method, the water temperature is maintained at 28-34 DEG C during the operation of a reactor, and the anaerobic ammonia oxidation granular sludge is placed in an environment of 14-17 DEG C after the reaction is finished. Compared with a method for continuously maintaining a medium-temperature environment, the method has the advantages that the energy is saved by about 30%, the activity of anaerobic ammonium oxidation bacteria and the nitrogen removal efficiency are remarkably improved, the highest total nitrogen removal rate can be improved by 5.16 times, real energy conservation and high efficiency are realized, and the method has a good application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of urban sewage treatment and regeneration, and specifically relates to a method for improving the efficiency of anaerobic ammonia oxidation denitrification based on variable temperature regulation. Background Art

[0002] Sewage denitrification has always been the focus and difficulty in the field of sewage treatment. Among them, nitrification and denitrification process is a mature sewage denitrification process. Nitrification reaction is the process in which ammonia oxidizing bacteria convert NH4 + -N is converted to NO2 - -N is eventually converted into NO3 - -N process, denitrification reaction refers to the process in which denitrifying bacteria convert NO3 - -N and NO2 - The process of reducing -N to N2 is a long, complex and energy-intensive process, which runs counter to the dual carbon goal. The discovery of anaerobic ammonium oxidation broke this path and directly converted NH4 + -N and NO2 - -N is converted to NO3 - -N and N2, compared with the traditional nitrification and denitrification process, it can save about 60% of aeration energy and 100% of carbon source. Due to its low energy consumption and low cost, the anaerobic ammonium oxidation process has been widely studied by scholars at home and abroad, but on the contrary, the anaerobic ammonium oxidation process has not been widely used in the field of water treatment engineering. Temperature is the biggest obstacle to the promotion of engineering application of anaerobic ammonium oxidation. The temperature drops in winter, and the inlet water temperature of the sewage treatment plant is low, but anaerobic ammonium oxidizing bacteria is a mesophilic bacteria. Low temperature poses a challenge to the efficient and stable operation of anaerobic ammonium oxidation. Anaerobic ammonium oxidation can be started and the reaction can be run in a low temperature environment, but the load is generally low. Technicians usually intervene by heating or cold acclimation to maintain a higher load.

[0003] Temperature is an important environmental factor that affects the activity of microorganisms. Low temperature poses several challenges to the survival of microorganisms, such as reduced enzyme activity, changes in protein structure, and reduced membrane fluidity, which have a wide range of effects on the functions of microorganisms, including cell metabolism disorders, reduced gene copy number, weakened nutrient absorption, blocked energy cycles, and slowed growth rates. If there is an environment where multiple microorganisms work together, low temperature may also affect the communication mechanism between different microorganisms and destroy the stable reaction system. Anaerobic ammonium oxidizing bacteria are extremely sensitive to environmental changes and have a long growth cycle. As a mesophilic bacterium, its living environment has high requirements for temperature. A large number of studies have shown that the optimal temperature range for anaerobic ammonium oxidation is 30-35°C. Most technologies related to anaerobic ammonium oxidation operate in the medium temperature range of 30-35°C. In order to maintain a medium temperature environment, factories often need to consume a lot of energy, which significantly increases the economic cost and the difficulty of process control. In addition, nitrite nitrogen is an important substrate for anaerobic ammonium oxidation reactions. Maintaining the dominant position of anaerobic ammonium oxidation in the denitrification function requires a stable source of nitrite nitrogen. However, nitrite nitrogen is also a bridge for nitrification and denitrification reactions. Anaerobic ammonium oxidizing bacteria are usually at a disadvantage when competing with nitrifying bacteria and denitrifying bacteria for nitrite nitrogen, and their living space is squeezed. How to ensure the living space of anaerobic ammonium oxidizing bacteria is the key to stable engineering operation. Therefore, it is of great significance to develop a method that does not require long-term maintenance of medium temperature conditions, reduces temperature maintenance energy consumption, and maintains or enhances anaerobic ammonium oxidation activity. Summary of the invention

[0004] In order to solve the problem of low efficiency and high consumption of anaerobic ammonium oxidation in low temperature environment, the purpose of the present invention is to provide a method for enhancing the activity of anaerobic ammonium oxidizing bacteria and improving denitrification efficiency by variable temperature regulation. The present invention uses a variable temperature regulation strategy, utilizes low temperature regulation to reduce gene competition, optimize material transfer and maintain intracellular stability to improve the denitrification efficiency of anaerobic ammonium oxidation, maintains a low temperature environment (14-17°C) during the reaction stop stage, and restores a medium temperature environment (28-34°C) during the reaction. First, the inhibitory factors nxrB and nirS genes of the anaerobic ammonium oxidation system are related to nitrite nitrogen metabolism. Their abundance (in terms of copy number) is significantly reduced at low temperatures, and the competition for nitrite nitrogen is reduced, which is conducive to maintaining the dominant position of anaerobic ammonium oxidation denitrification; secondly, anaerobic ammonium oxidizing bacteria can secrete a large amount of extracellular polymers (EPS) composed of proteins and polysaccharides. A large amount of EPS hinders the effective transfer of substrates such as ammonia nitrogen and nitrite nitrogen. The low temperature environment reduces the secretion of EPS and improves the efficiency of substrate transfer; finally, the cold shock proteins (CSPs) and molecular chaperone proteins possessed by anaerobic ammonium oxidizing bacteria can stabilize the secondary structure of RNA and DNA under low temperature conditions, and maintain efficient transcription, translation and DNA replication. Therefore, the present invention can play the uniqueness of anaerobic ammonium oxidizing bacteria by temperature regulation, better maintain activity in a low temperature environment, reduce cell damage, and thus maintain a more superior denitrification performance.

[0005] Compared with other methods for maintaining the activity of anaerobic ammonia oxidation, the present invention has the following advantages: first, compared with conventional optimum temperature operation, the denitrification rate (NRR) of this variable temperature control strategy can be increased by about 5 times at most, and the particle structure is better maintained. Secondly, the variable temperature strategy does not need to control the dissolved oxygen during actual operation, which simplifies the difficulty of implementation. Finally, the variable temperature strategy does not need to maintain a temperature above 30°C all the time, which reduces energy consumption. The implementation of the variable temperature strategy can reduce energy consumption by about 30% compared to maintaining a medium temperature environment (assuming that the reactor needs to maintain a water temperature of 30°C in a 15°C environment), realizing a truly energy-saving and environmentally friendly water treatment process.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control, specifically:

[0008] For the anaerobic ammonium oxidation granular sludge reactor, the water temperature is maintained at 28-34℃ during operation. After the operation, the 28-34℃ water is discharged, and the remaining anaerobic ammonium oxidation granular sludge is placed in an environment of 14-17℃ for 5-10 hours. The low temperature environment is used to reduce the copy number of other related metabolic genes that compete with anaerobic ammonium oxidizing bacteria for nitrite nitrogen, reduce the activity of related enzymes, and avoid EPS hindering mass transfer. The water temperature is maintained at 28-34℃ in the next operation cycle, thereby achieving an increase in the total nitrogen removal rate and removal rate of the anaerobic ammonium oxidation granular sludge in the next operation cycle.

[0009] Preferably, in the anaerobic ammonium oxidation granular sludge reactor, the sludge concentration MLSS (mixed liquor suspended solids concentration) is 1723-3450.2 mg / L. The sludge concentration MLSS refers to the suspended solids content of the mixed liquor after the sewage and activated sludge are mixed.

[0010] Preferably, in the anaerobic ammonium oxidation granular sludge reactor, the influent matrix of the sludge wastewater contains 70-92 mg / L NH4 + -N, 105-130mg / L NO2 - -N, pH is 7.62-8.2, and DO is 0.49-1.6 mg / L.

[0011] Preferably, the stirring operation time of one operation cycle of the anaerobic ammonium oxidation granular sludge reactor is 2.25-10 hours.

[0012] Preferably, the anaerobic ammonium oxidation granular sludge reactor is an anaerobic ammonium oxidation granular sludge sequencing batch reactor (SBR).

[0013] Preferably, the influent of the anaerobic ammonium oxidation granular sludge reactor is artificial simulated water or actual wastewater.

[0014] Preferably, the number of operation cycles is ≥5, and the total nitrogen removal rate begins to increase from the sixth cycle.

[0015] After the present invention implements the variable temperature control strategy, the total nitrogen removal rate is significantly improved compared with the traditional method of maintaining a medium temperature environment, with a maximum improvement of 5.16 times.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0017] (1) The present invention can improve the activity of anaerobic ammonium oxidizing bacteria without interfering with dissolved oxygen and maintaining a medium temperature environment for a long time, thereby strengthening the anaerobic ammonium oxidation effect and achieving a better denitrification effect in the reactor.

[0018] (2) The variable temperature control strategy implemented in the present invention can enhance the denitrification activity of the anaerobic ammonium oxidation granular sludge and better maintain the particle structure and color of the granular sludge.

[0019] (3) The variable temperature control strategy implemented in the present invention can reduce energy consumption by about 30% compared with maintaining a medium temperature environment (assuming that the reactor needs to maintain a water temperature of 30°C in an environment of 15°C). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The morphology of granular sludge is compared after Example 1 of the present invention implements the variable temperature control strategy and Comparative Example 1 maintains the medium temperature environment reactor for 68 days.

[0021] Figure 2 The percentage of total nitrogen removal rate improvement when the temperature-variable control strategy is implemented in Example 1 of the present invention and the medium-temperature environment reactor is maintained for 68 days (102 cycles) compared with the comparative example 1, the total nitrogen removal rate improvement percentage (%) = (total nitrogen removal rate of the temperature-variable control group - total nitrogen removal rate of the medium-temperature environment group) / total nitrogen removal rate of the medium-temperature environment group * 100%.

[0022] Figure 3 The reactor (V) in Example 1 of the present invention that implements the variable temperature control strategy and the reactor (C) in Comparative Example 1 that always maintains the nxrB gene copy number in the medium temperature environment.

[0023] Figure 4 The nirS gene copy number of the reactor (V) in Example 1 of the present invention that implements the variable temperature control strategy and the reactor (C) in Comparative Example 1 that always maintains the medium temperature environment are shown.

[0024] Figure 5 The EPS content of the reactor (V) in Example 1 of the present invention, which implements the variable temperature control strategy, and the reactor (C) in Comparative Example 1, which always maintains a medium temperature environment, is PN, and PS is a polysaccharide.

[0025] Figure 6 The inlet ammonia nitrogen concentration and nitrite nitrogen concentration of the reactor (V) implementing the variable temperature control strategy in Example 1 of the present invention during the operation cycle, wherein Inf. and eff. refer to the inlet water and the outlet water, respectively.

[0026] Figure 7 The sludge concentration MLSS of the reactor (V) during the operation cycle is obtained by implementing the variable temperature control strategy in Example 1 of the present invention.

[0027] Figure 8 The system pH of the reactor (V) during the operation cycle in which the variable temperature control strategy is implemented in Example 1 of the present invention, wherein Inf. and eff. refer to the inlet and outlet water, respectively.

[0028] Fig. 9 The DO value of the system of the reactor (V) implementing the variable temperature control strategy in the operation cycle of Example 1 of the present invention, wherein Inf. and eff. refer to the inlet and outlet water respectively. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with examples and drawings, but the embodiments of the present invention are not limited thereto.

[0030] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. All raw materials, reagents, etc., whose manufacturers are not specified, are conventional products that can be purchased commercially.

[0031] The reactor used in the embodiments of the present invention and the comparative examples is a sequencing batch reactor (SBR), the effective volume of the reactor is 5L, the sludge concentration MLSS is 1723-3450.2mg / L, and a stirring device is installed on the upper part of the reactor to ensure that the mud and water are mixed evenly, and the effluent is sucked out by a peristaltic pump. The test influent ammonia nitrogen concentration is 70-92mg / L, nitrite nitrogen concentration is 105-128mg / L, pH is 7.62-8.2, DO is 0.49-1.6mg / L, and pH is adjusted using sodium bicarbonate.

[0032] Example 1

[0033] When the reactor is in operation, the water temperature is maintained at 31°C, and the operation cycle is stirred for 10 hours, and the stirring device is turned off after 10 hours. After the operation is completed, the 31°C water is discharged, and the remaining anaerobic ammonia oxidation granular sludge is placed in an ambient temperature of 15°C for 10 hours. When the next operation cycle begins, take out the reactor and place it in a room temperature environment. The operating temperature is restored to 30°C and stirred for 10 hours. Repeat the above operation cycle (maintain the water temperature at 30°C and stir for 2.25-10 hours during a single cycle, and place it in an ambient temperature of 15°C after the end. The single placement time is 5-10 hours). The experiment lasted 68 days, for a total of 102 cycles.

[0034] Figure 3-4 It showed that with the increase of the number of operation cycles, the gene copy numbers of other metabolic genes related to anaerobic ammonium oxidation competing with nitrite nitrogen, such as nxrB and nirS, were 2.13×10 8 and 5.32×10 9 copies / g, which is reduced by about 74% and 58% compared with the reactor with the same operation period in which the operating temperature and the reactor environment temperature are maintained at 30°C (Comparative Example 1). Figure 5 It shows that the PN and PS contents of EPS are 193.69 and 39.16 mg / g, respectively, which are reduced by about 19% and 13% compared with the reactor with the same operating cycle in which the operating temperature and the reactor ambient temperature are maintained at 30°C (Comparative Example 1), effectively reducing the EPS's barrier to ammonia nitrogen and nitrous oxide mass transfer. Figure 2 It shows that compared with the reactor with the same operating cycle in which the operating temperature and the ambient temperature of the reactor are maintained at 30°C (Comparative Example 1), the total nitrogen removal rate increased from 0.01 times at the beginning to 5.16 times (102nd operating cycle). The number of copies of nitrite nitrogen metabolism genes and EPS content decreased, anaerobic ammonia oxidation was in a dominant position in the competition for nitrite nitrogen, and the mass transfer barrier was reduced, which successfully improved the denitrification effect of anaerobic ammonia oxidation granular sludge. Compared with the reactor that always maintains a medium temperature environment, the energy consumption can be reduced by about 30% (assuming that the reactor needs to maintain a water temperature of 30°C in an environment of 15°C). At the same time, the sludge basically maintains the granular form and the color is light brown.

[0035] Comparative Example 1

[0036] When the reactor is in operation, the water temperature is maintained at 31°C, and the operation cycle is stirred for 10 hours, and the stirring device is turned off after 10 hours. After the operation is completed, the 31°C water is discharged, and the remaining anaerobic ammonia oxidation granular sludge is placed in an ambient temperature of 30°C for 10 hours. When the next operation cycle begins, take out the reactor and place it in a room temperature environment. The operating temperature continues to be maintained at 30°C and stirred for 10 hours. Repeat the above operation cycle (maintain the water temperature at 30°C and stir for 2.25-10 hours during a single cycle. The operation time of the same repeated cycle is exactly the same as in Example 1. After the end, it is placed in an ambient temperature of 30°C, and the placement time of the same cycle is exactly the same as in Example 1). The experiment was carried out for 68 days, for a total of 102 cycles.

[0037] Compared with the reactor placed at 15°C ambient temperature after the operation was stopped in Example 1, Figure 3-4 It shows that with the increase of the number of running cycles, the gene copy numbers of nxrB and nirS in the later stage of this comparative example are 8.11×10 8 and 1.26×10 10 copies / g, which increased by about 2.3 times and 1.38 times compared with the reactor implementing the variable temperature strategy. Figure 5 The results showed that the PN and PS contents of EPS were 239.69 and 45.10 mg / g, respectively, which were increased by about 24% and 15% compared with the reactor implementing the variable temperature strategy. However, the total nitrogen removal rate was only 0.16 times that of the reactor implementing the variable temperature strategy ( Figure 2 ), and more serious particle disintegration occurred, and the color appeared dark brown and black, indicating that the activity of anaerobic ammonium oxidation particles was poor.

[0038] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control, characterized in that: Specifically: For the anaerobic ammonium oxidation granular sludge reactor, the water temperature is maintained at 28-34℃ during operation. After the operation, the 28-34℃ water is discharged, and the remaining anaerobic ammonium oxidation granular sludge is placed in an environment of 14-17℃ for 5-10 hours. The low temperature environment is used to reduce the copy number of other related metabolic genes that compete with anaerobic ammonium oxidizing bacteria for nitrite nitrogen, reduce the activity of related enzymes, and avoid EPS hindering mass transfer. The water temperature is maintained at 28-34℃ in the next operation cycle, thereby achieving an increase in the total nitrogen removal rate and removal rate of the anaerobic ammonium oxidation granular sludge in the next operation cycle.

2. According to claim 1, a method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control, characterized in that: In the anaerobic ammonium oxidation granular sludge reactor, the influent matrix of the sludge wastewater contains 70-92 mg / L NH4 + -N, 105-130mg / L NO2 - -N.

3. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: The stirring operation time of one operation cycle of the anaerobic ammonium oxidation granular sludge reactor is 2.25-10 hours.

4. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: In the anaerobic ammonium oxidation granular sludge reactor, the sludge concentration MLSS is 1723-3450.2 mg / L.

5. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: In the anaerobic ammonium oxidation granular sludge reactor, the inlet matrix pH of the sludge wastewater is 7.62-8.

2.

6. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: In the anaerobic ammonium oxidation granular sludge reactor, the influent matrix DO of the sludge wastewater is 0.49-1.6 mg / L.

7. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: The influent of the anaerobic ammonium oxidation granular sludge reactor is artificial simulated water or actual wastewater.

8. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: The anaerobic ammonium oxidation granular sludge reactor is an anaerobic ammonium oxidation granular sludge sequencing batch reactor.

9. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: The water temperature is maintained at 30-31°C under the operating state.

10. A method for improving the efficiency of anaerobic ammonium oxidation denitrification by temperature control according to claim 1 or 2, characterized in that: The number of operation cycles is ≥5.

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