Regulation method for enhancing denitrification of sewage by endogenous denitrification

Abstract

The application provides a method for regulating and controlling wastewater denitrification by endogenous denitrification, comprising the following steps: step S1, setting initial operation conditions; step S2, setting multiple operation modes, including mode one, mode two and mode three; step S3, regulating and controlling wastewater denitrification according to temperature, influent nitrogen load concentration and effluent standards. The application is flexible in application and simple in management, and can realize three operation modes, namely mode one of denitrification by only external denitrification, mode two of denitrification by external denitrification and endogenous denitrification in a post-anoxic zone, and mode three of denitrification by endogenous denitrification. Good treatment effect can be realized by only simple regulation and control according to different requirements, and the application is suitable for wastewater treatment plants of different scales.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and more specifically, to a method for regulating wastewater denitrification through endogenous denitrification. Background Technology

[0002] With the rapid development of the human economy, environmental pollution has become increasingly serious. Currently, with increasingly stringent wastewater discharge standards, effectively removing pollutants from wastewater with low C / N ratios in an energy-efficient and economical manner to meet these increasingly stringent quality standards is a significant challenge facing wastewater treatment plants.

[0003] Currently, wastewater treatment plant processes can be broadly categorized into pre-denitrification and post-denitrification. Pre-denitrification uses organic matter in the influent as an electron donor to remove nitrogen in the anoxic zone. However, the high recirculation ratio introduces a large amount of dissolved oxygen into the anoxic zone, disrupting the anoxic environment, and is also costly, typically ranging from 100% to 200%. Therefore, the nitrogen removal efficiency is limited by the recirculation ratio, making it difficult to achieve deep nitrogen removal. Post-denitrification, without an external carbon source, removes nitrogen through endogenous denitrification. Endogenous denitrifying microorganisms store organic matter as an intracellular carbon source (PHAs or Gly) under anaerobic conditions and then use this intracellular carbon source as an electron donor for denitrification under anoxic conditions. Theoretically, this process can achieve complete nitrogen removal, but its disadvantages include a slow endogenous denitrification rate, a long hydraulic retention time in the anoxic zone, and unstable nitrification at low temperatures.

[0004] Existing processes fail to meet the diverse needs of wastewater treatment plants. When influent conditions, environmental conditions, and effluent standards change, there is a risk of effluent exceeding standards during certain periods. The only solutions are to add carbon sources, reduce influent volume, or upgrade standards, which increases operating and investment costs or requires the plant to be shut down for renovation. This is detrimental to the operation of the plant and the achievement of carbon emission reduction goals.

[0005] Therefore, how to provide a process or device that is flexible in application, energy-saving and consumption-reducing, has good treatment effect and simple management, and solves the problem that the effluent is difficult to stably meet the standards due to seasonal temperature changes, increased influent load or improved effluent standards in the sewage treatment process is an urgent technical problem that needs to be solved in the sewage treatment field. Summary of the Invention

[0006] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a method for regulating wastewater denitrification enhanced by endogenous denitrification.

[0007] According to the present invention, a method for regulating wastewater denitrification enhanced by endogenous denitrification is provided, which employs a wastewater denitrification device, the wastewater denitrification device comprising: an anaerobic zone, an anaerobic-anoxic switchable zone, an aerobic-anoxic switchable zone, a sedimentation tank, an internal reflux pipe for nitrified liquid, and an external reflux pipe for sludge.

[0008] The anaerobic zone, the anaerobic-hypoxic switchable zone, and the aerobic-hypoxic switchable zone are sequentially distributed and connected;

[0009] The aerobic-anoxic switchable zone is connected to the sedimentation tank, and the sedimentation tank is connected to the anaerobic zone and the aerobic-anoxic switchable zone through the sludge external return pipe;

[0010] The aerobic-anoxic switchable zone is connected to the anaerobic-anoxic switchable zone via the nitrification liquid reflux pipe.

[0011] Preferably, the anaerobic zone is provided with a first return port, the aerobic-anoxic switchable zone is provided with a third return port, and the sludge external return pipe is connected to the first return port and the third return port.

[0012] Preferably, a third return pump is installed on the branch line connecting the sludge external return pipe to the first return port, and a fourth return pump is installed on the branch line connecting the sludge external return pipe to the third return port.

[0013] Preferably, the anaerobic-anoxic switchable zone is provided with a second reflux port, one end of the nitrification liquid reflux pipe is connected to the second reflux port, and the other end is connected to the front and rear sections of the aerobic-anoxic switchable zone respectively.

[0014] Preferably, a first reflux pump is installed on the branch connecting the nitrification liquid internal reflux pipe to the front section of the aerobic-anoxic switchable zone, and a second reflux pump is installed on the branch connecting the nitrification liquid internal reflux pipe to the rear section of the aerobic-anoxic switchable zone.

[0015] Preferably, a stirring or flow-generating device is provided in the latter part of the anaerobic zone, the anaerobic-anoxic switchable zone, and the aerobic-anoxic switchable zone;

[0016] Aeration equipment is installed in the aerobic-anoxic switchable zone.

[0017] Preferably, the first return port, the second return port, and the third return port are connected to the control system, the first return pump, the second return pump, the third return pump, and the fourth return pump are connected to the control system, and the aeration equipment is connected to the control system.

[0018] Preferably, the control system includes: an inlet flow meter, online water temperature and total nitrogen monitoring instruments, online ammonia nitrogen and total nitrogen monitoring instruments, and a transmission analysis and control module;

[0019] The anaerobic zone is equipped with the influent flow meter and the online water temperature and total nitrogen monitoring instruments, and the sedimentation tank is equipped with online ammonia nitrogen and total nitrogen monitoring instruments. The influent flow meter, the online water temperature and total nitrogen monitoring instruments, and the online ammonia nitrogen and total nitrogen monitoring instruments are connected to the transmission analysis and control module.

[0020] Preferably, the transmission analysis and control module is connected to the electric gate of the first return port, the second return port, and the third return port, the first return pump, the second return pump, the third return pump, the fourth return pump, and the aeration device.

[0021] Preferably, the method for regulating wastewater nitrogen removal enhanced by endogenous denitrification includes the following steps:

[0022] Step S1, set the initial operating conditions: nitrification liquor return ratio is 100%, sludge return ratio is 100%, sludge concentration is set at 3000-4000 mg / L, and DO (dissolved oxygen) concentration in the aerobic-anoxic switchable zone is set at 1-2 mg / L;

[0023] Step S2, set three operating modes:

[0024] In Mode 1, the influent sequentially passes through the anaerobic zone, the anaerobic-anoxic switchable zone, the aerobic-anoxic switchable zone, and the sedimentation tank. The stirring or flow-generating equipment in the anaerobic zone and the anaerobic-anoxic switchable zone is activated, as is the aeration equipment in the aerobic-anoxic switchable zone. The first return port, the second return port, the second return pump, and the third return pump are also activated. In Mode 1, the anaerobic-anoxic switchable zone functions as an anoxic zone, and the aerobic-anoxic switchable zone functions as an aerobic zone. The volume ratio of the anaerobic zone, the anoxic zone, and the aerobic zone in the anaerobic-anoxic switchable zone is 1:1:4.

[0025] In Mode 2, the influent sequentially passes through the anaerobic zone, the anaerobic-anoxic switchable zone, the aerobic-anoxic switchable zone, and the sedimentation tank. The stirring or flow-generating equipment in the anaerobic zone and the anaerobic-anoxic switchable zone is activated. The aeration equipment at the front end and the stirring or flow-generating equipment at the rear end of the aerobic-anoxic switchable zone are also activated. The first return port, the second return port, the first return pump, and the third return pump are also activated. In Mode 2, the anaerobic-anoxic switchable zone functions as an anoxic zone, the front end of the aerobic-anoxic switchable zone functions as an aerobic zone, and the rear end functions as an anoxic zone. The volume ratio of the anaerobic zone, the anoxic zone of the anaerobic-anoxic switchable zone, the aerobic zone of the aerobic-anoxic switchable zone, and the anoxic zone of the aerobic-anoxic switchable zone is 1:1:2:2.

[0026] In Mode 3, the influent sequentially passes through the anaerobic zone, the anaerobic-anoxic switchable zone, the aerobic-anoxic switchable zone, and the sedimentation tank. The stirring or flow-generating equipment in the anaerobic zone and the anaerobic-anoxic switchable zone is activated. The aeration equipment at the front end and the stirring or flow-generating equipment at the rear end of the aerobic-anoxic switchable zone are also activated. The first return port, the third return port, the third return pump, and the fourth return pump are also activated. In Mode 3, the anaerobic-anoxic switchable zone functions as an anaerobic zone, the front end of the aerobic-anoxic switchable zone functions as an aerobic zone, and the rear end functions as an anoxic zone. The volume ratio of the anaerobic zone and the anaerobic zone of the anaerobic-anoxic switchable zone, and the aerobic zone and the anoxic zone of the aerobic-anoxic switchable zone is 2:2:2.

[0027] Step S3, methods for regulating seasonal temperature changes:

[0028] When T < 20℃, using Mode 1 in step S2, the volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:1:4. If NH4+ + -N EFF If ≤5mg / L, then maintain the initial operating conditions set in step S1. If NH4 + -N EFF If the concentration of DO in the aerobic zone of the switchable aerobic-anoxic zone is greater than 5 mg / L, the aeration rate can be increased by increasing the aeration rate of the aeration equipment to control the concentration of DO in the aerobic-anoxic zone to 2-3 mg / L.

[0029] When T≥20℃, use either Mode 2 or Mode 3 in step S2. In Mode 2, the volume ratio of the anaerobic, anoxic, aerobic, and anoxic zones is 1:1:2:2; in Mode 3, the volume ratio is 2:2:2. If NH4+... + -N EFF If ≤5mg / L, then maintain the initial operating conditions set in step S1. If NH4 + -N EFF If the concentration of DO in the aerobic zone of the switchable aerobic-anoxic zone is greater than 5 mg / L, the aeration rate can be increased by increasing the aeration rate of the aeration equipment to control the concentration of DO in the aerobic-anoxic zone to 2-3 mg / L.

[0030] The water temperature is T, measured in °C, and the effluent index is ammonia nitrogen concentration, expressed as NH4+. + -N EFF It indicates that the unit is mg / L;

[0031] Step S4, methods for controlling changes in influent nitrogen load concentration:

[0032] When TN INF ≤40mg / L and Q≤Q0, adopt Mode 1 in step S2, with the volume ratio of anaerobic zone, anoxic zone, and aerobic zone being 1:1:4. If TN EFFIf ≤15mg / L, maintain the initial operating conditions set in step S1; if TN EFF If the concentration is >15 mg / L, the nitration reflux ratio can be increased to 200% by increasing the power of the second reflux pump.

[0033] When TN INF ≤40mg / L and Q>Q0, or TN INF If the concentration is >40 mg / L and Q < Q0, then mode two in step S2 is adopted, with the volume ratio of anaerobic, anoxic, aerobic, and anoxic zones being 1:1:2:2. If TN EFF If ≤15mg / L, maintain the initial operating conditions set in step S1; if TN EFF If the concentration is >15 mg / L, the nitration reflux ratio can be increased to 200% by increasing the power of the second reflux pump.

[0034] When TN INF >40mg / L and Q>Q0, adopt mode three in step S2, with the volume ratio of anaerobic zone, aerobic zone and anoxic zone being 2:2:2. If TN EFF If ≤15mg / L, maintain the initial operating conditions set in step S1; if TN EFF If the concentration is >15mg / L, the sludge return ratio to the anoxic zone of the aerobic-anoxic switchable zone can be increased to 150% by increasing the power of the fourth return pump.

[0035] Among them, total nitrogen in the influent is mainly TN INF The unit is mg / L. The actual influent volume is represented by Q, with the unit being m³. 3 / h, the design water volume is expressed as Q0, and the unit is m³. 3 / h, the effluent index is total nitrogen concentration, expressed as TN EFF It indicates that the unit is mg / L;

[0036] Step S5, Control methods for changes in effluent standards:

[0037] When the effluent standard is lower than the Class A standard, the first mode in step S2 is adopted, with the volume ratio of the anaerobic zone, anoxic zone and aerobic zone being 1:1:4.

[0038] When the effluent standard is higher than or equal to the Class A standard, switch to Mode 2 in step S2, with the volume ratio of the anaerobic zone, anoxic zone, aerobic zone and anoxic zone being 1:1:2:2. If the effluent meets the standard, maintain the operating conditions set in Mode 2 and the initial settings in step S1. If the effluent does not meet the standard, switch to Mode 3 in step S2, with the volume ratio of the aerobic zone, aerobic zone and anoxic zone being 2:2:2.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. This application is flexible in application and simple in management, and can realize three operating modes: mode one, which removes nitrogen by external denitrification alone; mode two, which enhances nitrogen removal by external denitrification and endogenous denitrification in the post-anoxic zone; and mode three, which removes nitrogen by endogenous denitrification. Good treatment results can be achieved with simple adjustment to meet different needs, and it is suitable for wastewater treatment plants of different sizes.

[0041] 2. This application has good treatment effect and stable effluent. By switching, it can solve the problem of effluent that is difficult to meet the standards due to seasonal temperature changes, increased influent load or improved effluent standards during the sewage treatment process.

[0042] 3. This application makes full use of internal carbon sources and saves energy and reduces consumption. By switching, it can achieve enhanced denitrification through internal denitrification. Specifically, in Mode 2 and Mode 3, the internal denitrifying microorganisms in the anaerobic zone store organic matter in the influent into their cells in the form of internal carbon sources. In the anoxic zone of the switchable aerobic and anoxic zones in Mode 2 and Mode 3, where there is no available external organic matter, the internal carbon sources are used as electron donors for internal denitrification, eliminating the need to add carbon sources and saving treatment costs. In addition, in some modes, switching from the aerobic zone to the anoxic zone can reduce aeration energy consumption.

[0043] 4. This application has high denitrification efficiency and can achieve deep denitrification. By switching part of the aerobic zone to the anoxic zone, it solves the problem that the reflux ratio in the nitrification liquor of the traditional AAO process limits the denitrification efficiency, and can achieve complete denitrification.

[0044] 5. The sludge production of this application is low. In some modes, the sludge production can be reduced by endogenous denitrification and increasing the sludge retention time. Attached Figure Description

[0045] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0046] Figure 1 This is a schematic diagram of a wastewater denitrification device;

[0047] Figure 2 This is a schematic diagram of the control method;

[0048] As shown in the figure:

[0049]

[0050] Detailed Implementation

[0051] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0052] Example 1

[0053] like Figure 1 As shown, this embodiment includes: an anaerobic zone 1, an anaerobic-anoxic switchable zone 2, an aerobic-anoxic switchable zone 3, a sedimentation tank 4, an internal reflux pipe 5 for nitrified liquid, and an external reflux pipe 6 for sludge. The anaerobic zone 1, anaerobic-anoxic switchable zone 2, and aerobic-anoxic switchable zone 3 are sequentially connected. The aerobic-anoxic switchable zone 3 is connected to the sedimentation tank 4. The sedimentation tank 4 is connected to the anaerobic zone 1 and the aerobic-anoxic switchable zone 3 via the external reflux pipe 6. The aerobic-anoxic switchable zone 3 is connected to the anaerobic-anoxic switchable zone 2 via the internal reflux pipe 5 for nitrified liquid. A stirring or flow-promoting device 11 is installed in the downstream sections of the anaerobic zone 1, the anaerobic-anoxic switchable zone 2, and the aerobic-anoxic switchable zone 3. An aeration device 31 is installed in the aerobic-anoxic switchable zone 3.

[0054] A first return port 61 is installed at the front of anaerobic zone 1, and a third return port 62 is installed at the front of aerobic-anoxic switchable zone 3. An external sludge return pipe 6 is connected to both the first and third return ports 61 and 62. A third return pump 63 is installed on the branch connecting the external sludge return pipe 6 to the first return port 61, and a fourth return pump 64 is installed on the branch connecting the external sludge return pipe 6 to the third return port 62. A second return port 51 is installed in anaerobic-anoxic switchable zone 2. One end of the nitrification liquid internal return pipe 5 is connected to the second return port 51, and the other end is connected to the middle and rear sections of aerobic-anoxic switchable zone 3. A first return pump 52 is installed on the branch connecting the internal nitrification liquid return pipe 5 to the middle section of aerobic-anoxic switchable zone 3, and a second return pump 53 is installed on the branch connecting the internal nitrification liquid return pipe 5 to the rear section of aerobic-anoxic switchable zone 3.

[0055] The control system 7 includes: an influent flow meter 71, an online water temperature and total nitrogen monitoring instrument 72, an online ammonia nitrogen and total nitrogen monitoring instrument 73, and a transmission analysis and control module 74. The influent flow meter 71 and the online water temperature and total nitrogen monitoring instrument 72 are installed at the front end of the anaerobic zone 1, and the online ammonia nitrogen and total nitrogen monitoring instrument 73 is installed in the sedimentation tank 4. The influent flow meter 71, the online water temperature and total nitrogen monitoring instrument 72, and the online ammonia nitrogen and total nitrogen monitoring instrument 73 are connected to the transmission analysis and control module 74. The transmission analysis and control module 74 is connected to the electric gates of the first return port 61, the second return port 51, and the third return port 62, the first return pump 52, the second return pump 53, the third return pump 63, the fourth return pump 64, and the aeration equipment 31.

[0056] like Figure 2As shown, the control method of the device in this embodiment includes the following steps:

[0057] Step S1: Set initial operating conditions: nitrification liquor return ratio is 100%, sludge return ratio is 100%, sludge concentration is set at 3000-4000 mg / L, and DO concentration in aerobic-anoxic switchable zone 3 is set at 1-2 mg / L.

[0058] Step S2: Set three operating modes: Mode 1: Influent flows sequentially through anaerobic zone 1, anaerobic-anoxic switchable zone 2, aerobic-anoxic switchable zone 3, and sedimentation tank 4. The stirring or propulsion equipment 11 of anaerobic zone 1 and anaerobic-anoxic switchable zone 2 is turned on, the aeration equipment 31 of aerobic-anoxic switchable zone 3 is turned on, and the first return port 61, the second return port 51, the second return pump 53, and the third return pump 63 are turned on. In Mode 1, anaerobic-anoxic switchable zone 2 functions as an anoxic zone, and aerobic-anoxic switchable zone 3 functions as an aerobic zone. The volume ratio of the anaerobic zone of anaerobic zone 1, the anoxic zone of anaerobic-anoxic switchable zone 2, and the aerobic zone of aerobic-anoxic switchable zone 3 is 1:1:4. The microorganisms in the anaerobic and anoxic zones use the organic matter in the influent to reduce nitrate nitrogen in the nitrification liquid returned from the sludge external return to nitrogen gas to achieve denitrification. The microorganisms in the aerobic zone convert ammonia nitrogen in the influent into nitrate nitrogen. Nitrogen removal occurs in the anaerobic and anoxic zones, primarily driven by external carbon sources. In Mode 2, the influent sequentially passes through anaerobic zone 1, the anaerobic-anoxic switchable zone 2, the aerobic-anoxic switchable zone 3, and sedimentation tank 4. The stirring or flow-generating equipment 11 in anaerobic zone 1 and the anaerobic-anoxic switchable zone 2 is activated. The aeration equipment 31 in the first half and the stirring or flow-generating equipment 11 in the second half of the aerobic-anoxic switchable zone 3 are activated. The first return port 61, the second return port 51, the first return pump 52, and the third return pump 63 are also activated. In Mode 2, the anaerobic-anoxic switchable zone 2 functions as an anoxic zone, and the first section of the aerobic-anoxic switchable zone 3 functions as an aerobic zone, while the latter section functions as an anoxic zone. The anaerobic zone of anaerobic zone 1 and the anoxic zone of the anaerobic-anoxic switchable zone 2... The volume ratio of the aerobic zone and the anoxic zone in the aerobic-anoxic switchable zone 3 is 1:1:2:2. The microorganisms in the anaerobic zone use part of the organic matter in the influent for nitrate nitrogen in the denitrification sludge return and part for storage of intracellular carbon sources. The microorganisms in the anoxic zone use the organic matter in the influent to reduce nitrate nitrogen in the nitrification liquid return to nitrogen gas to achieve denitrification. The microorganisms in the aerobic zone convert ammonia nitrogen in the influent into nitrate nitrogen. The microorganisms in the post-anoxic zone use intracellular carbon sources to further reduce nitrate nitrogen. Denitrification mainly occurs in the anaerobic and anoxic zones and is mainly driven by external carbon sources. Part of it occurs in the post-anoxic zone and is driven by internal carbon sources.In Mode 3, the influent sequentially passes through anaerobic zone 1, anaerobic-anoxic switchable zone 2, aerobic-anoxic switchable zone 3, and sedimentation tank 4. The mixing or flow-generating equipment 11 in anaerobic zone 1 and anaerobic-anoxic switchable zone 2 is activated. The aeration equipment 31 in the first half and the mixing or flow-generating equipment 11 in the second half of aerobic-anoxic switchable zone 3 are activated. The first return port 61, the third return port 62, the third return pump 63, and the fourth return pump 64 are activated. In Mode 3, anaerobic-anoxic switchable zone 2 functions as an anaerobic zone, the first section of aerobic-anoxic switchable zone 3 functions as an aerobic zone, and the second section functions as an anoxic zone. Anaerobic zone 1 and anaerobic-anoxic switchable zone 4... The volume ratio of the anaerobic zone in Zone 2, the aerobic zone in Zone 3 (which can be switched between aerobic and anoxic), and the anoxic zone in Zone 3 is 2:2:2. The microorganisms in the anaerobic zone utilize part of the organic matter in the influent for nitrate nitrogen in the denitrification sludge return and part for storage of intracellular carbon sources. The microorganisms in the aerobic zone convert ammonia nitrogen in the influent into nitrate nitrogen. The microorganisms in the anoxic zone utilize intracellular carbon sources for denitrification. Simultaneously, the sludge return to the anoxic zone increases the sludge concentration in the anoxic zone, thereby enhancing the denitrification effect of endogenous denitrification. Denitrification mainly occurs in the anoxic zone, primarily driven by internal carbon sources and enhanced by sludge return.

[0059] Step S3, control method for seasonal temperature changes: When T < 20℃, use Mode 1 from Step S2, with the volume ratio of anaerobic, anoxic, and aerobic zones being 1:1:4. If NH4+ + -N EFF If ≤5mg / L, then maintain the initial operating conditions set in step S1. If NH4 + -N EFF If the concentration of DO in the aerobic zone of the switchable aerobic / anoxic zone 3 is greater than 5 mg / L, the aeration rate is increased by aeration equipment 31 to control the DO concentration to 2-3 mg / L. When T ≥ 20℃, either Mode 2 or Mode 3 in step S2 is used. In Mode 2, the volume ratio of the anaerobic, anoxic, aerobic, and anoxic zones is 1:1:2:2, and in Mode 3, the volume ratio is 2:2:2. If NH4+... + -N EFF If ≤5mg / L, then maintain the initial operating conditions set in step S1. If NH4 + -N EFF If the concentration is >5 mg / L, the aeration rate is increased by aeration equipment 31 to control the DO concentration in the aerobic zone of the switchable aerobic / anoxic zone 3 to 2-3 mg / L; where water temperature is T (°C) and effluent index is ammonia nitrogen concentration, expressed as NH4+. + -N EFF It indicates that the unit is mg / L.

[0060] Step S4, the method for controlling changes in influent nitrogen load concentration: when TN INF≤40mg / L and Q≤Q0, adopt Mode 1 in step S2, with the volume ratio of anaerobic zone, anoxic zone, and aerobic zone being 1:1:4. If TN EFF If ≤15mg / L, maintain the initial operating conditions set in step S1; if TN EFF If the concentration is >15 mg / L, the nitration reflux ratio can be increased to 200% by increasing the power of the second reflux pump 53; when TN INF ≤40mg / L and Q>Q0, or TN INF If the concentration is >40 mg / L and Q < Q0, then mode two in step S2 is adopted, with the volume ratio of anaerobic, anoxic, aerobic, and anoxic zones being 1:1:2:2. If TN EFF If ≤15mg / L, maintain the initial operating conditions set in step S1; if TN EFF If the concentration is >15 mg / L, the nitration reflux ratio can be increased to 200% by increasing the power of the second reflux pump 53; when TN INF >40mg / L and Q>Q0, adopt mode three in step S2, with the volume ratio of anaerobic zone, aerobic zone and anoxic zone being 2:2:2. If TN EFF If ≤15mg / L, maintain the initial operating conditions set in step S1; if TN EFF If the sludge concentration is >15mg / L, the sludge return ratio to the anoxic zone of the aerobic-anoxic switchable zone 3 will be increased to 150% by increasing the power of the fourth return pump 64; among which, the total nitrogen in the influent is expressed as TN. INF The unit is mg / L. The actual influent volume is represented by Q, with the unit being m³. 3 / h, the design water volume is expressed as Q0, and the unit is m³. 3 / h, the effluent index is total nitrogen concentration, expressed as TN EFF It indicates that the unit is mg / L.

[0061] Step S5, the control method for changes in effluent standards: When the effluent standard is lower than the Class A standard, use Mode 1 in Step S2, with a volume ratio of anaerobic, anoxic, and aerobic zones of 1:1:4; when the effluent standard is higher than or equal to the Class A standard, switch to Mode 2 in Step S2, with a volume ratio of anaerobic, anoxic, aerobic, and anoxic zones of 1:1:2:2. If the effluent meets the standard, maintain Mode 2 and the initial operating conditions set in Step S1; if the effluent does not meet the standard, switch to Mode 3 in Step S2, with a volume ratio of anaerobic, aerobic, and anoxic zones of 2:2:2.

[0062] In step S4, the nitrification reflux ratio is increased by increasing the power of the second reflux pump 53, and the sludge reflux ratio returned to the anoxic zone of the aerobic-anoxic switchable zone 3 is increased by increasing the power of the fourth reflux pump 64.

[0063] Example 2

[0064] Example 2 is a preferred example of Example 1.

[0065] like Figure 1 As shown, the anaerobic-anoxic switchable zone 2 can be switched to an anaerobic zone by closing the gate of the first reflux pump 52 or the second reflux pump 53 and the first reflux port 61, serving as a supplementary anaerobic zone and enhancing the internal carbon source storage function. The aerobic-anoxic switchable zone 3 can be switched to an anoxic zone by closing the downstream aeration equipment 31 and opening the downstream stirring or propulsion equipment 31, serving as a supplementary anoxic zone or a post-anoxic zone. At the same time, the gates of the first reflux pump 52, the second reflux pump 53 and the third reflux port 62 need to be adjusted according to specific needs, and it has the function of enhancing nitrogen removal through endogenous denitrification.

[0066] The device can achieve three operating modes: Mode 1, which removes nitrogen solely through external denitrification; Mode 2, which enhances nitrogen removal through external denitrification and endogenous denitrification in the post-anoxic zone; and Mode 3, which removes nitrogen through endogenous denitrification.

[0067] Mode 1: The influent flows sequentially through anaerobic zone 1, anaerobic-anoxic switchable zone 2, aerobic-anoxic switchable zone 3, and sedimentation tank 4. The stirring or propulsion equipment 11 of anaerobic zone 1 and anaerobic-anoxic switchable zone 2 is turned on, the aeration equipment 31 of aerobic-anoxic switchable zone 3 is turned on, and the first return port 61, the second return port 51, the second return pump 53, and the third return pump 63 are turned on.

[0068] In this mode, the anaerobic zone functions to denitrify nitrate and nitrite nitrogen from the returned sludge using organic matter in the influent, and to store the organic matter in the influent as an intracellular carbon source. The anaerobic-anoxic switchable zone 2 functions as an anoxic zone, using organic matter in the influent to denitrify nitrate and nitrite nitrogen from the returned nitrification liquor. The aerobic-anoxic switchable zone 3 functions as an aerobic zone, converting ammonia nitrogen in the influent into nitrite and nitrate nitrogen. This mode has a longer aerobic retention time, making it suitable for periods of low temperature and poor nitrification efficiency, such as winter. Furthermore, the nitrogen removal efficiency is affected by the nitrification liquor return ratio, making it suitable for situations with low influent load and low effluent standards.

[0069] Mode 2: The influent flows sequentially through anaerobic zone 1, anaerobic-anoxic switchable zone 2, aerobic-anoxic switchable zone 3, and sedimentation tank 4. The stirring or propulsion equipment 11 of anaerobic zone 1 and anaerobic-anoxic switchable zone 2 is turned on. The aeration equipment 31 in the first half and the stirring or propulsion equipment 11 in the second half of aerobic-anoxic switchable zone 3 are turned on. The first return port 61, the second return port 51, the first return pump 52, and the third return pump 63 are turned on.

[0070] In this mode, the anaerobic zone functions by denitrifying nitrate and nitrite nitrogen from the returned sludge using organic matter in the influent, and storing the organic matter in the influent as an intracellular carbon source. The anaerobic-anoxic switchable zone 2 functions as an anoxic zone, using organic matter in the influent to denitrify nitrate and nitrite nitrogen from the returned nitrified liquid. The aerobic-anoxic switchable zone 3 functions as a first half aerobic zone and a second half anoxic zone. The first half aerobic zone converts ammonia nitrogen in the influent into nitrite and nitrate nitrogen, while the second half anoxic zone uses intracellular carbon sources to reduce some of the nitrite and nitrate nitrogen produced in the aerobic zone back to nitrogen gas, thus enhancing denitrification. This mode has a short aerobic retention time, making it suitable for seasons with higher water temperatures and meeting the requirements of high influent loads and high effluent standards.

[0071] Mode 3:

[0072] The influent flows sequentially through anaerobic zone 1, anaerobic-anoxic switchable zone 2, aerobic-anoxic switchable zone 3, and sedimentation tank 4. The stirring or propulsion equipment 11 of anaerobic zone 1 and anaerobic-anoxic switchable zone 2 is turned on. The aeration equipment 31 of the first half and the stirring or propulsion equipment 11 of the second half of aerobic-anoxic switchable zone 3 are turned on. The first return port 61, the third return port 62, the third return pump 63, and the fourth return pump 64 are turned on.

[0073] In this mode, the anaerobic zone functions to utilize organic matter in the influent for denitrification and return of nitrate and nitrite nitrogen to the sludge, and to store the organic matter in the influent as an intracellular carbon source. The anaerobic-anoxic switchable zone 2 functions as an anaerobic zone, further enhancing the storage of intracellular carbon sources. The aerobic-anoxic switchable zone 3 functions as a first half aerobic zone and a second half anoxic zone. The first half aerobic zone converts ammonia nitrogen in the influent into nitrite and nitrate nitrogen, while the second half anoxic zone removes nitrogen through endogenous denitrification and enhances nitrogen removal through sludge return. This mode has a short aerobic retention time, making it suitable for seasons with higher water temperatures, and can meet the requirements of low influent carbon-to-nitrogen ratios, high influent loads, and high effluent standards.

[0074] In one specific implementation, the device of this embodiment was applied in a single series of a wastewater treatment plant with a daily treatment capacity of 160,000 tons, a hydraulic retention time of 12 hours, and an effluent standard of Class A. The single series used the Mode 3 process. The comparison period was 300 days.

[0075] The series of applications using this device and control method are as follows: When the water temperature is below 20℃, operate in Mode 1. To enhance nitrification during the initial switching phase, adjust the aeration rate to control the dissolved oxygen (DO) concentration at 2-3 mg / L. After the effluent ammonia nitrogen level stabilizes below 5 mg / L and remains so for 15 days, control the DO concentration at 1-2 mg / L. When the water temperature exceeds 20℃, switch to Mode 3, and the effluent ammonia nitrogen level stabilizes below 5 mg / L. During the low-temperature period in winter, the instantaneous ammonia nitrogen compliance rate is 99.2%.

[0076] Comparative Study: Operating year-round using the Mode 3 process, nitrification was unstable during the low-temperature winter months. Furthermore, simply increasing aeration caused some delays, leading to momentary spikes in ammonia nitrogen levels in the effluent. The compliance rate for momentary ammonia nitrogen levels in the effluent during the low-temperature winter months was only 78.7%.

[0077] In one specific implementation, the device of this embodiment was applied in a small-scale test with a daily treatment capacity of 120L. The small-scale device was equipped with a heating device to maintain a constant water temperature of 23±0.2℃. This control method was applied to a single series, while the control series operated only in Mode 1. The control period was 180 days.

[0078] Series using this control method:

[0079] When TN INF For concentrations ≤40 mg / L and Q≤Q0, use Mode 1 with a volume ratio of 1:1:4.

[0080] If TN EFF If the concentration is ≤15mg / L, the initial operating conditions will be maintained.

[0081] If TN EFF If the concentration is >15 mg / L, increase the nitrification reflux ratio to 200%.

[0082] When TN INF ≤40mg / L and Q>Q0, or TN INF If the concentration is >40 mg / L and Q < Q0, then mode 2 is adopted, with a volume ratio of 1:1:2:2.

[0083] If TN EFF If the concentration is ≤15mg / L, the initial operating conditions will be maintained.

[0084] If TN EFF If the concentration is >15 mg / L, increase the nitrification reflux ratio to 200%.

[0085] When TN INF If the concentration is >40 mg / L and Q > Q0, then mode 3 is adopted with a volume ratio of 2:2:2.

[0086] If TN EFF If the concentration is ≤15mg / L, the initial operating conditions will be maintained.

[0087] If TN EFF If the concentration is >15 mg / L, increase the sludge return ratio to the anoxic zone to 150%.

[0088] The influent and effluent indicators of the two series are compared as shown in Table 1 below. Table 1 is a data comparison table of influent load changes.

[0089] In one implementation, this device is applied to the biological treatment section of a wastewater treatment plant with a daily treatment capacity of 80,000 tons. The initial planned effluent standard is Class B, and operation in Mode 1 consistently meets this standard. However, when the treatment standard is upgraded to Class A, Mode 1, due to limitations in its denitrification process, cannot achieve deep denitrification, and the total nitrogen (TN) cannot consistently remain below 15 mg / L. By switching to Mode 2 for enhanced denitrification, the effluent consistently meets the Class A standard. This upgrade achieves the desired process standard without requiring shutdown or modification.

[0090] The effluent quality before and after the upgrade is shown in Table 2 below. Table 2 is a data comparison table under different standard conditions.

[0091] COD (mg / L) Ammonia nitrogen (mg / L) Total nitrogen (mg / L) Water ingress 207.0±18.5 56.2±7.5 58.1±6.9 Application series water outlet 16.6±7.7 0.5±0.6 6.2±2.2 Comparison series water output 18.6±3.9 0.8±0.3 16.0±5.3

[0092] Table 1

[0093] COD (mg / L) Ammonia nitrogen (mg / L) Total nitrogen (mg / L) Before raising the price - Mode 1 27.6±3.8 0.5±0.6 15.9±3.8 After raising the standard - Mode 2 24.6±3.1 0.8±0.3 11.0±1.9

[0094] Table 2

[0095] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0096] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for regulating and controlling wastewater nitrogen removal through endogenous denitrification, characterized in that, Includes the following steps: Step S1: Set initial running conditions; Step S2: Set multiple operating modes, including: Mode 1, Mode 2 and Mode 3; Step S3: Adjust wastewater denitrification according to temperature, influent nitrogen load concentration, and effluent standards; The method for controlling wastewater denitrification based on the influent nitrogen load concentration in step S3 is as follows: When TN INF If ≤ second threshold and Q≤Q0, adopt mode one in step S2, with the volume ratio of anaerobic zone, anoxic zone, and aerobic zone being 1:1:

4. If TN EFF If TN ≤ the third threshold, then maintain the initial operating conditions set in step S1. EFF If the third threshold is reached, the nitration reflux ratio is increased to 200%. When TN INF ≤ the second threshold and Q > Q0, or TN INF > The second threshold and Q < Q0, adopt mode two in step S2, with the volume ratio of anaerobic zone, anoxic zone, aerobic zone and anoxic zone being 1:1:2:2, if TN EFF If TN ≤ the third threshold, then maintain the initial operating conditions set in step S1. EFF If the third threshold is reached, the nitration reflux ratio is increased to 200%. When TN INF > The second threshold and Q > Q0, adopt mode three in step S2, with the volume ratio of anaerobic zone, aerobic zone and anoxic zone being 2:2:2, if TN EFF If TN ≤ the third threshold, then maintain the initial operating conditions set in step S1. EFF If the threshold is reached, the sludge return ratio to the anoxic zone is increased to 150%. Among them, total nitrogen in the influent is mainly TN INF The unit is mg / L. The actual influent volume is represented by Q, with the unit being m³. 3 / h, the design water volume is expressed as Q0, and the unit is m³. 3 / h, the effluent index is total nitrogen concentration, expressed as TN EFF It indicates that the unit is mg / L.

2. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 1, characterized in that, The initial operating conditions of step S1 include: nitrification liquor return ratio of 100%, sludge return ratio of 100%, sludge concentration set at 3000-4000 mg / L, and DO concentration set at 1-2 mg / L in the aerobic-anoxic switchable zone (3).

3. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 1, characterized in that, The method for controlling wastewater denitrification based on temperature changes in step S3 is as follows: When T < 20℃, using Mode 1 in step S2, the volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:1:

4. If NH4+ + -N EFF If NH4 ≤ the first threshold, then maintain the initial operating conditions set in step S1. + -N EFF >The first threshold is then used to increase the aeration rate through the aeration equipment (31) to control the DO concentration in the aerobic zone to 2-3 mg / L; When T≥20℃, use either Mode 2 or Mode 3 in step S2. When using Mode 2, the volume ratio of the anaerobic, anoxic, aerobic, and anoxic zones is 1:1:2:2; when using Mode 3, the volume ratio is 2:2:

2. If NH4+... + -N EFF If NH4 ≤ the first threshold, then maintain the initial operating conditions set in step S1. + -N EFF >The first threshold is then used to increase the aeration rate through the aeration equipment (31) to control the DO concentration in the aerobic zone to 2-3 mg / L; The water temperature is T, measured in °C, and the effluent index is ammonia nitrogen concentration, expressed as NH4+. + -N EFF It indicates that the unit is mg / L.

4. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 1, characterized in that, The method for controlling wastewater denitrification in step S3 according to effluent standards: When the effluent standard is lower than the Class A standard, the first mode in step S2 is adopted, with the volume ratio of the anaerobic zone, anoxic zone and aerobic zone being 1:1:

4. When the effluent standard is higher than or equal to the Class A standard, switch to Mode 2 in step S2, with the volume ratio of the anaerobic zone, anoxic zone, aerobic zone and anoxic zone being 1:1:2:

2. If the effluent meets the standard, maintain the operating conditions set in Mode 2 and the initial settings in step S1. If the effluent does not meet the standard, switch to Mode 3 in step S2, with the volume ratio of the anaerobic zone, aerobic zone and anoxic zone being 2:2:

2.

5. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 3, characterized in that: The first threshold is 5 mg / L, the second threshold is 40 mg / L, and the third threshold is 15 mg / L.

6. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 1, characterized in that, The wastewater denitrification device includes: an anaerobic zone (1), an anaerobic-anoxic switchable zone (2), an aerobic-anoxic switchable zone (3), a sedimentation tank (4), an internal nitrification liquid return pipe (5), and an external sludge return pipe (6). The anaerobic zone (1), the anaerobic-hypoxic switchable zone (2), and the aerobic-hypoxic switchable zone (3) are sequentially distributed and connected; The aerobic-anoxic switchable zone (3) is connected to the sedimentation tank (4), and the sedimentation tank (4) is connected to the anaerobic zone (1) and the aerobic-anoxic switchable zone (3) through the sludge external return pipe (6). The aerobic-anoxic switchable zone (3) is connected to the anaerobic-anoxic switchable zone (2) through the nitrification liquid reflux pipe (5); A stirring or propulsion device (11) is installed in the rear section of the anaerobic zone (1), the anaerobic-anoxic switchable zone (2), and the aerobic-anoxic switchable zone (3), and an aeration device (31) is installed in the aerobic-anoxic switchable zone (3).

7. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 6, characterized in that: The anaerobic zone (1) is provided with a first return port (61), the aerobic-anoxic switchable zone (3) is provided with a third return port (62), and the sludge external return pipe (6) is connected to the first return port (61) and the third return port (62). A third return pump (63) is installed on the branch connecting the sludge external return pipe (6) to the first return port (61), and a fourth return pump (64) is installed on the branch connecting the sludge external return pipe (6) to the third return port (62). The anaerobic-anoxic switchable zone (2) is provided with a second reflux port (51). One end of the nitrification liquid reflux pipe (5) is connected to the second reflux port (51), and the other end is connected to the front and rear sections of the aerobic-anoxic switchable zone (3) respectively. A first reflux pump (52) is installed on the branch connecting the nitrification liquid internal reflux pipe (5) to the front section of the aerobic-anoxic switchable zone (3), and a second reflux pump (53) is installed on the branch connecting the nitrification liquid internal reflux pipe (5) to the rear section of the aerobic-anoxic switchable zone (3).

8. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 7, characterized in that: The electric gates of the first return port (61), the second return port (51) and the third return port (62) are connected to the control system (7), the first return pump (52), the second return pump (53), the third return pump (63) and the fourth return pump (64) are connected to the control system (7), and the aeration device (31) is connected to the control system (7). The control system (7) includes: an inlet flow meter (71), an online water temperature and total nitrogen monitoring instrument (72), an online ammonia nitrogen and total nitrogen monitoring instrument (73), and a transmission analysis control module (74). The anaerobic zone (1) is equipped with the influent flow meter (71) and the online water temperature and total nitrogen monitoring instrument (72). The sedimentation tank (4) is equipped with the online ammonia nitrogen and total nitrogen monitoring instrument (73). The influent flow meter (71), the online water temperature and total nitrogen monitoring instrument (72) and the online ammonia nitrogen and total nitrogen monitoring instrument (73) are connected to the transmission analysis and control module (74). The transmission analysis and control module (74) is connected to the first return port (61), the second return port (51), the third return port (62), the first return pump (52), the second return pump (53), the third return pump (63), the fourth return pump (64), and the aeration device (31).

9. The method for regulating wastewater nitrogen removal enhanced by endogenous denitrification according to claim 7, characterized in that, In step S2, modes one, two, and three satisfy the following: In Mode 1, the influent passes sequentially through the anaerobic zone (1), the anaerobic-anoxic switchable zone (2), the aerobic-anoxic switchable zone (3), and the sedimentation tank (4). The stirring or propulsion equipment (11) of the anaerobic zone (1) and the anaerobic-anoxic switchable zone (2) is turned on, the aeration equipment (31) of the aerobic-anoxic switchable zone (3) is turned on, and the first return port (61), the second return port (51), the second return pump (53), and the third return pump (63) are turned on. In Mode 1, the anaerobic-anoxic switchable zone (2) functions as an anoxic zone, and the aerobic-anoxic switchable zone (3) functions as an aerobic zone. The volume ratio of the anaerobic zone of the anaerobic zone (1), the anoxic zone of the anaerobic-anoxic switchable zone (2), and the aerobic zone of the aerobic-anoxic switchable zone (3) is 1:1:

4. In mode two, the influent flows sequentially through the anaerobic zone (1), the anaerobic-anoxic switchable zone (2), the aerobic-anoxic switchable zone (3), and the sedimentation tank (4). The stirring or flow-generating equipment (11) of the anaerobic zone (1) and the anaerobic-anoxic switchable zone (2) is turned on. The aeration equipment (31) at the front end and the stirring or flow-generating equipment (11) at the rear end of the aerobic-anoxic switchable zone (3) are turned on. The first return port (61) and the second return port (51) are turned on. The first reflux pump (52) and the third reflux pump (63) in Mode 2, the anaerobic-hypoxia switchable zone (2) functions as a hypoxia zone, the front section of the aerobic-hypoxia switchable zone (3) functions as an aerobic zone and the rear section functions as a hypoxia zone, the volume ratio of the anaerobic zone (1), the hypoxia zone of the anaerobic-hypoxia switchable zone (2), the aerobic zone of the aerobic-hypoxia switchable zone (3), and the hypoxia zone of the aerobic-hypoxia switchable zone (3) is 1:1:2:2; Mode 3: The influent flows sequentially through the anaerobic zone (1), the anaerobic-anoxic switchable zone (2), the aerobic-anoxic switchable zone (3), and the sedimentation tank (4). The stirring or flow-generating equipment (11) of the anaerobic zone (1) and the anaerobic-anoxic switchable zone (2) is turned on. The aeration equipment (31) at the front end and the stirring or flow-generating equipment (11) at the rear end of the aerobic-anoxic switchable zone (3) are turned on. The first return port (61) and the third return port (62) are turned on. The third reflux pump (63) and the fourth reflux pump (64) in Mode 3, the anaerobic-anoxic switchable zone (2) functions as an anaerobic zone, the front section of the aerobic-anoxic switchable zone (3) functions as an aerobic zone and the rear section functions as an anoxic zone, the volume ratio of the anaerobic zone (1) and the anaerobic-anoxic switchable zone (2), the aerobic zone of the aerobic-anoxic switchable zone (3) and the anoxic zone of the aerobic-anoxic switchable zone (3) is 2:2:2.

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