A device and method for quickly inhibiting nitrite oxidizing bacteria to achieve advanced nitrogen and phosphorus removal of municipal wastewater

Abstract

This invention relates to an apparatus and method for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal in urban wastewater, belonging to the field of biological wastewater treatment. The apparatus includes an influent reactor unit, an influent unit, an aeration unit, and an effluent unit. The method operates a short-cut nitrification / anaerobic ammonium oxidation system with low nitrogen and phosphorus removal efficiency due to the proliferation of nitrite-oxidizing bacteria in an anaerobic-aerobic-anoxic mode. By controlling the aerobic and anoxic time distributions, the nitrite accumulation rate in the aerobic section of the system is rapidly increased, reducing the total nitrogen and phosphate content in the effluent. This invention, by changing the operating mode, rapidly inhibits nitrite-oxidizing bacteria, improves the nitrogen and phosphorus removal efficiency of the short-cut nitrification / anaerobic ammonium oxidation system operating in an anaerobic-aerobic-anoxic mode, achieves deep nitrogen and phosphorus removal in urban wastewater with a low C / N ratio, and ensures stable operation. The operation and control are simple, requiring no external energy, thus saving energy and reducing consumption.

Description

Technical Field

[0001] This invention relates to a device and method for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep denitrification and phosphorus removal in urban wastewater, belonging to the field of biological wastewater treatment. Background Technology

[0002] Urban sewage is rich in nitrogen and phosphorus, which are essential nutrients for plants. When discharged into natural water bodies, it leads to the proliferation of algae and other organisms, the depletion of dissolved oxygen, and eutrophication. This has adverse effects on all aspects of human life and production, and can even directly harm human physical and mental health.

[0003] In urban wastewater treatment plants, nitrogen removal and phosphorus removal are typically carried out in separate reaction tanks. Nitrogen removal often employs traditional nitrification / denitrification biological nitrogen removal technologies, while phosphorus removal typically utilizes chemical phosphorus removal or a combination of biological and chemical phosphorus removal technologies. However, traditional nitrification / denitrification nitrogen removal technologies, limited by the finite carbon source in the raw water, struggle to meet increasingly stringent nitrogen removal standards. Furthermore, the nitrification / denitrification processes require significant aeration energy consumption and carbon source depletion, making traditional wastewater treatment a high-energy-consuming process. Chemical phosphorus removal, on the other hand, requires the addition of chemical reagents, further increasing treatment costs.

[0004] The discovery and research of anaerobic ammonium oxidation (ANAO) technology has provided a new approach for biological nitrogen removal from urban wastewater. Short-cut nitrification / ANAO is a widely studied biological nitrogen removal technology. Short-cut nitrification can oxidize some of the ammonia nitrogen in urban wastewater into nitrite, providing nitrite as a substrate for ANAO. The anoxic ANAO stage utilizes ammonia nitrogen and nitrite for autotrophic nitrogen removal, which can greatly save aeration energy consumption and eliminate the need for an external carbon source.

[0005] Utilizing an anaerobic-aerobic-anoxic operating mode, nitrogen removal primarily relies on endogenous denitrification in the post-anoxic stage, fully utilizing the carbon source in the raw water and achieving energy conservation and reduced consumption. Furthermore, this anaerobic-aerobic-anoxic operating mode promotes the accumulation of endogenous denitrifying phosphorus-accumulating bacteria, facilitating simultaneous deep nitrogen and phosphorus removal from urban wastewater. However, in actual operation, nitrite-oxidizing bacteria often proliferate excessively in the aerobic stage, making it difficult for the system to provide sufficient nitrite for anaerobic ammonia-oxidizing bacteria. Additionally, in the prolonged anoxic stage, the release of phosphorus by anaerobic organisms hinders stable phosphorus removal by denitrifying phosphorus-accumulating bacteria.

[0006] Based on the problems and challenges faced in the denitrification and phosphorus removal process of urban wastewater, this invention transforms the anaerobic-aerobic-anoxic operation mode into an anaerobic-aerobic-anoxic-aerobic-anoxic mode. By controlling the aerobic and anoxic time distribution, it rapidly improves the nitrite accumulation rate in the aerobic section and the denitrification phosphorus removal performance of the short-cut nitrification / anaerobic ammonium oxidation system, which suffers from low denitrification and phosphorus removal efficiency due to the proliferation of nitrite-oxidizing bacteria. This achieves deep denitrification and phosphorus removal of urban wastewater with a low carbon-to-nitrogen ratio and stable operation. This invention is simple to operate and control, requires no external energy, and provides the necessary theoretical basis and technical support for deep treatment of urban wastewater and energy conservation and consumption reduction, possessing significant research significance and application value. Summary of the Invention

[0007] This invention proposes a device and method for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal in urban wastewater. It utilizes an anaerobic-aerobic-anoxic-aerobic-anoxic cycle to operate a short-cut nitrification / anaerobic ammonium oxidation system, which suffers from low nitrogen and phosphorus removal efficiency due to the proliferation of nitrite-oxidizing bacteria. By controlling the distribution of aerobic and anoxic time periods, the nitrite accumulation rate in the aerobic phase of the system is rapidly increased, thereby improving the system's denitrification and phosphorus removal performance. This achieves deep nitrogen and phosphorus removal in urban wastewater with a low C / N ratio and ensures stable operation. This invention is simple to operate and control, requires no external energy source, and provides a new approach to inhibiting nitrite-oxidizing bacteria and simultaneously achieving deep nitrogen and phosphorus removal in urban wastewater with a low C / N ratio.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A device for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal in urban wastewater is characterized by comprising a reactor unit, an inlet unit, an aeration unit, and an outlet unit. The reactor unit includes an SBR reactor (1), a stirring device (2), an inlet (5), an aeration port (8), an outlet (10), an overflow port (11), a sludge discharge port (12), and a pH / DO meter (13); the inlet unit includes a raw water tank (3) and an inlet peristaltic pump (4); the aeration unit includes an aeration pump (6), a flow meter (7), and a microporous aeration disc (9); and the outlet unit includes an outlet tank (14).

[0010] During operation, urban sewage in the raw water tank (3) is pumped into the SBR reactor (1) by the inlet peristaltic pump (4) through the inlet (5); the stirring device (2) drives the mud and water in the reactor to mix and react; during the aerobic stage, the aeration pump (6) is operated, and the gas enters the system through the flow meter (7), aeration port (8), and microporous aeration disc (9) to contact the activated sludge. The aeration volume is controlled by the flow meter (7); after completing the anaerobic, aerobic, and anoxic reactions, the mud and water are separated by sedimentation, and the effluent is discharged from the outlet (10) to the outlet tank (14); during sludge discharge, the sludge is discharged from the system through the sludge discharge port (12).

[0011] A method for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal in urban wastewater, characterized by comprising the following steps:

[0012] (1) Phase 1: This phase is from day 1 to day 114 of operation. The short-range nitrification / anaerobic ammonia oxidation system threatened by the proliferation of nitrite-oxidizing bacteria is operated in an anaerobic-aerobic-anoxic mode.

[0013] Phase 1: System operation comprises five parts: influent, operation, sedimentation, drainage, and idle. Operation includes anaerobic mixing, aerobic aeration, and anoxic mixing. The anaerobic duration is 1.5 hours, including 10 minutes of influent. Sedimentation time is 10 minutes, drainage time is 10 minutes, and the drainage ratio is 50%. From day 1 to day 31, the aeration duration is 2.5 hours; from day 32 to day 57, the aeration duration is 5 hours; from day 58 to day 65 and from day 97 to day 101, the aeration duration is 4 hours; and from day 102 to day 114, the aeration duration is 3 hours. From day 1 to day 31, the system hypoxia duration was 7.5 hours, the idle time was 10 minutes, and the HRT was 23 hours, with two cycles per day. From day 32 to day 48, the system hypoxia duration was 11 hours, the idle time was 6 hours and 10 minutes, and the HRT was 35 hours, with one cycle per day. From day 49 to day 57, the system hypoxia duration was 4 hours, the idle time was 70 minutes, and the HRT was 21 hours, with two cycles per day. From day 58 to day 65 and from day 97 to day 101, the system hypoxia duration was 5 hours, the idle time was 70 minutes, and the HRT was 21 hours, with two cycles per day. From day 102 to day 114, the system hypoxia duration was 6 hours, the idle time was 70 minutes, and the HRT was 21 hours, with two cycles per day.

[0014] The system's aerobic end dissolved oxygen is 1.5-2.0 mg / L, the operating temperature is 25℃, and the sludge concentration is 2000-3000 mg / L. The raw water is municipal sewage, with ammonia nitrogen concentration of 61.56-87.77 mg / L; phosphate concentration of 6.73-10.79 mg / L; and COD / TIN of 2.86-4.55.

[0015] To control nitrite-oxidizing bacteria, measures were taken including adjusting the pH at the end of the anaerobic cycle, increasing aeration, sludge removal, and anaerobic starvation. From day 49 to 56, the pH at the end of the anaerobic cycle was adjusted to 8 using sodium hydroxide. The dissolved oxygen at the end of the aerobic cycle was 2-2.5 mg / L. Sludge was removed from the system from day 104 to 114, with a sludge age of 25-30 days. From day 66 to 96, the system underwent anaerobic starvation treatment, with no influent and no aeration.

[0016] (2) Phase Two: This phase lasts for 155 days or more. The system from Phase One continues to operate in an anaerobic-aerobic-anoxic-aerobic-anoxic mode. The operation mode is changed to inhibit nitrite-oxidizing bacteria and increase the activity of ammonia-oxidizing bacteria, anaerobic ammonia-oxidizing bacteria, and polyphosphate-accumulating bacteria.

[0017] Phase Two: System operation comprises five parts: influent, operation, sedimentation, drainage, and idle. The operating mode is anaerobic-aerobic-anoxic-aerobic-anoxic. The durations of each phase (anaerobic-aerobic-anoxic-aerobic-anoxic) are 1.5h, 1.5h, 2h, 1.5h, and 4h, respectively. The anaerobic phase includes 10 minutes of influent, 10 minutes of sedimentation, and 10 minutes of drainage (drainage ratio 50%). The idle time is 70 minutes, the HRT (Heat Retention Time) is 21 hours, and the system operates for two cycles per day. The dissolved oxygen at the end of the aerobic phase is 2-2.5 mg / L, the operating temperature is 25℃, the sludge age is 25-30 days, and the sludge concentration is 2000-3000 mg / L. The raw water is urban sewage, with ammonia nitrogen concentration of 64.09-84.66 mg / L; phosphate concentration of 6.24-10.24 mg / L; and COD / TIN of 3.26-4.24.

[0018] A device and method for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal in urban wastewater has the following advantages compared with existing technologies:

[0019] 1) By changing the operating mode, the rapid inhibition of nitrite-oxidizing bacteria is achieved, the nitrite accumulation rate in the aerobic section is increased, and the operation is simple and easy to control.

[0020] 2) The reasonable distribution of aerobic and anoxic time allows polyphosphate-accumulating bacteria to accumulate in large quantities, thus improving the system's phosphorus removal efficiency.

[0021] 3) The rapid increase in nitrite accumulation in the aerobic stage provides more substrate for anaerobic ammonia oxidation in the anoxic stage, thereby improving the system's nitrogen removal efficiency.

[0022] 4) The denitrification and phosphorus removal performance is rapidly improved, enabling the system to achieve deep denitrification and phosphorus removal and maintain stable operation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a device for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal from urban wastewater.

[0024] Figure 2 This refers to the operation mode of the reactor in stage two.

[0025] Figure 3 This data represents the long-term operational data of the reactor during nitrogen and phosphorus removal in stages one and two.

[0026] Figure 1In the middle: 1-SBR reactor, 2-stirring device, 3-raw water tank, 4-inlet peristaltic pump, 5-inlet, 6-aeration pump, 7-flow meter, 8-aeration port, 9-microporous aeration disc, 10-outlet, 11-overflow port, 12-sludge discharge port, 13-pH / DO meter, 14-outlet tank. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1 As shown, a device for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal in urban sewage is characterized by comprising a reactor unit, an inlet unit, an aeration unit, and an outlet unit. The reactor unit includes an SBR reactor (1), a stirring device (2), an inlet (5), an aeration port (8), an outlet (10), an overflow port (11), a sludge discharge port (12), and a pH / DO meter (13); the inlet unit includes a raw water tank (3) and an inlet peristaltic pump (4); the aeration unit includes an aeration pump (6), a flow meter (7), and a microporous aeration disc (9); and the outlet unit includes an outlet tank (14).

[0029] During operation, urban sewage in the raw water tank (3) is pumped into the SBR reactor (1) by the inlet peristaltic pump (4) through the inlet (5); the stirring device (2) drives the mud and water in the reactor to mix and react; during the aerobic stage, the aeration pump (6) is operated, and the gas enters the system through the flow meter (7), aeration port (8), and microporous aeration disc (9) to contact the activated sludge. The aeration volume is controlled by the flow meter (7); after completing the anaerobic, aerobic, and anoxic reactions, the mud and water are separated by sedimentation, and the effluent is discharged from the outlet (10) to the outlet tank (14); during sludge discharge, the sludge is discharged from the system through the sludge discharge port (12).

[0030] A method for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal in urban wastewater, characterized by comprising the following steps:

[0031] (1) Phase 1: This phase is from day 1 to day 114 of operation. The short-range nitrification / anaerobic ammonia oxidation system threatened by the proliferation of nitrite-oxidizing bacteria is operated in an anaerobic-aerobic-anoxic mode.

[0032] Phase 1: System operation comprises five parts: influent, operation, sedimentation, drainage, and idle. Operation includes anaerobic mixing, aerobic aeration, and anoxic mixing. The anaerobic duration is 1.5 hours, including 10 minutes of influent. Sedimentation time is 10 minutes, drainage time is 10 minutes, and the drainage ratio is 50%. From day 1 to day 31, the aeration duration is 2.5 hours; from day 32 to day 57, the aeration duration is 5 hours; from day 58 to day 65 and from day 97 to day 101, the aeration duration is 4 hours; and from day 102 to day 114, the aeration duration is 3 hours. From day 1 to day 31, the system hypoxia duration was 7.5 hours, the idle time was 10 minutes, and the HRT was 23 hours, with two cycles per day. From day 32 to day 48, the system hypoxia duration was 11 hours, the idle time was 6 hours and 10 minutes, and the HRT was 35 hours, with one cycle per day. From day 49 to day 57, the system hypoxia duration was 4 hours, the idle time was 70 minutes, and the HRT was 21 hours, with two cycles per day. From day 58 to day 65 and from day 97 to day 101, the system hypoxia duration was 5 hours, the idle time was 70 minutes, and the HRT was 21 hours, with two cycles per day. From day 102 to day 114, the system hypoxia duration was 6 hours, the idle time was 70 minutes, and the HRT was 21 hours, with two cycles per day.

[0033] The system's aerobic end dissolved oxygen is 1.5-2.0 mg / L, the operating temperature is 25℃, and the sludge concentration is 2000-3000 mg / L. The raw water is municipal sewage, with ammonia nitrogen concentration of 61.56-87.77 mg / L; phosphate concentration of 6.73-10.79 mg / L; and COD / TIN of 2.86-4.55.

[0034] To control nitrite-oxidizing bacteria, measures were taken including adjusting the pH at the end of the anaerobic cycle, increasing aeration, sludge removal, and anaerobic starvation. From day 49 to 56, the pH at the end of the anaerobic cycle was adjusted to 8 using sodium hydroxide. The dissolved oxygen at the end of the aerobic cycle was 2-2.5 mg / L. Sludge was removed from the system from day 104 to 114, with a sludge age of 25-30 days. From day 66 to 96, the system underwent anaerobic starvation treatment, with no influent and no aeration.

[0035] The various control measures implemented in Phase 1 failed to effectively control nitrite-oxidizing bacteria. During the final 10 days of this phase, the nitrite accumulation rate in the aerobic section ranged from 15% to 32%. The total nitrogen concentration in the effluent ranged from 13.56 to 29.26 mg / L, with a total nitrogen removal rate of 61% to 83%. The phosphate concentration ranged from 5.20 to 6.47 mg / L, with a phosphate removal rate of 15% to 37%. The COD removal rate was 81% to 88%. The system's nitrogen and phosphorus removal efficiency was low.

[0036] (2) Phase Two: This phase lasts for 155 days or more. The system from Phase One continues to operate in an anaerobic-aerobic-anoxic-aerobic-anoxic mode. The operation mode is changed to inhibit nitrite-oxidizing bacteria and increase the activity of ammonia-oxidizing bacteria, anaerobic ammonia-oxidizing bacteria, and polyphosphate-accumulating bacteria.

[0037] Phase Two: System operation comprises five parts: influent, operation, sedimentation, drainage, and idle. The operating mode is anaerobic-aerobic-anoxic-aerobic-anoxic. The durations of each phase (anaerobic-aerobic-anoxic-aerobic-anoxic) are 1.5h, 1.5h, 2h, 1.5h, and 4h, respectively. The anaerobic phase includes 10 minutes of influent, 10 minutes of sedimentation, and 10 minutes of drainage (drainage ratio 50%). The idle time is 70 minutes, the HRT (Heat Retention Time) is 21 hours, and the system operates for two cycles per day. The dissolved oxygen at the end of the aerobic phase is 2-2.5 mg / L, the operating temperature is 25℃, the sludge age is 25-30 days, and the sludge concentration is 2000-3000 mg / L. The raw water is urban sewage, with ammonia nitrogen concentration of 64.09-84.66 mg / L; phosphate concentration of 6.24-10.24 mg / L; and COD / TIN of 3.26-4.24.

[0038] Phase Two of the system achieved deep nitrogen and phosphorus removal from urban wastewater with a low carbon-to-nitrogen ratio. After 20 days of operation, the nitrite accumulation rate in the aerobic stage increased from 26% to 60%, subsequently stabilizing at 65%-70%. In the final 10 days of this phase, the total nitrogen concentration in the effluent ranged from 3.43 to 10.14 mg / L, with a total nitrogen removal rate of 87%-96%. The phosphate concentration ranged from 0 to 0.13 mg / L, with a phosphate removal rate of 98%-100%. The COD removal rate was 82%-92%.

[0039] The above are specific embodiments of the present invention, which enable those skilled in the art to better understand and apply the present invention. However, the implementation of the present invention is not limited thereto. Therefore, any simple improvements made to the present invention by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for rapidly inhibiting nitrite-oxidizing bacteria to achieve deep nitrogen and phosphorus removal from urban wastewater, the apparatus of which includes a reactor unit, an influent unit, an aeration unit, and an effluent unit; The reactor unit includes an SBR reactor (1), a stirring device (2), an inlet (5), an aeration port (8), an outlet (10), an overflow port (11), a sludge discharge port (12), and a pH / DO meter (13); the water inlet unit includes a raw water tank (3) and a water inlet peristaltic pump (4); the aeration unit includes an aeration pump (6), a flow meter (7), and a microporous aeration disc (9); the water outlet unit includes an outlet tank (14). During operation, urban sewage in the raw water tank (3) is pumped into the SBR reactor (1) by the inlet peristaltic pump (4) through the inlet (5); the stirring device (2) drives the sludge and water in the SBR reactor to mix and react; during the aerobic stage, the aeration pump (6) is operated, and the gas enters the system through the flow meter (7), aeration port (8), and microporous aeration disc (9) to contact the activated sludge, and the aeration volume is controlled by the flow meter (7); after completing the anaerobic, aerobic, and anoxic reactions, the sludge and water are separated by sedimentation, and the effluent is discharged from the outlet (10) to the outlet tank (14); during sludge discharge, the sludge is discharged from the system through the sludge discharge port (12); Its features are, Includes the following steps: (1) Phase 1: This phase is from day 1 to day 114 of operation; the short-range nitrification / anaerobic ammonia oxidation system threatened by the proliferation of nitrite-oxidizing bacteria is operated in an anaerobic-aerobic-anoxic mode. Phase 1: System operation comprises five parts: influent, operation, sedimentation, drainage, and idle. Operation includes anaerobic mixing, aerobic aeration, and anoxic mixing. The anaerobic duration is 1.5 hours, including 10 minutes of influent; sedimentation time is 10 minutes, drainage time is 10 minutes, and the drainage ratio is 50%. From day 1 to day 31, the aeration duration is 2.5 hours; from day 32 to day 57, the aeration duration is 5 hours; from day 58 to day 65 and from day 97 to day 101, the aeration duration is 4 hours; from day 102 to day 114, the aeration duration is 3 hours; from day 1 to day 31, the anoxic duration is 7.5 hours, and the idle time is 10 minutes. The system operates for 23 hours per day, with two cycles per day. From day 32 to day 48, the system experiences 11 hours of hypoxia and 6 hours and 10 minutes of idle time, with a total HRT of 35 hours per day, operating once per day. From day 49 to day 57, the system experiences 4 hours of hypoxia and 70 minutes of idle time, with a total HRT of 21 hours per day, operating twice per day. From day 58 to day 65 and from day 97 to day 101, the system experiences 5 hours of hypoxia and 70 minutes of idle time, with a total HRT of 21 hours per day, operating twice per day. From day 102 to day 114, the system experiences 6 hours of hypoxia and 70 minutes of idle time, with a total HRT of 21 hours per day, operating twice per day. The system's aerobic end dissolved oxygen is 1.5-2.0 mg / L, operating temperature is 25℃, and sludge concentration is 2000-3000 mg / L; the raw water is municipal sewage, with ammonia nitrogen concentration of 61.56-87.77 mg / L, phosphate concentration of 6.73-10.79 mg / L, and COD / TIN of 2.86-4.

55. To control nitrite-oxidizing bacteria, measures were taken including adjusting the pH at the end of the anaerobic cycle, increasing aeration, sludge removal, and anaerobic starvation. From day 49 to day 56 of operation, the pH at the end of the anaerobic cycle was adjusted to 8 with sodium hydroxide; the dissolved oxygen at the end of the aerobic cycle was 2-2.5 mg / L; sludge was removed from the system from day 104 to day 114, with a sludge age of 25-30 days; from day 66 to day 96, the system underwent anaerobic starvation treatment of the sludge, with no water inflow and no aeration. (2) Phase 2: This phase is the 155th day or more of system operation; the system in Phase 1 continues to operate in the anaerobic-aerobic-hypoxic-aerobic-hypoxic mode; Phase Two: The system operation consists of five parts: water inlet, operation, sedimentation, drainage, and idle. The operation mode is anaerobic-aerobic-anoxic-aerobic-anoxic. The durations of each phase of the anaerobic-aerobic-anoxic-aerobic-anoxic system are 1.5h, 1.5h, 2h, 1.5h, and 4h, respectively. The anaerobic time includes 10 minutes of influent; 10 minutes of sedimentation and 10 minutes of effluent discharge, with a discharge ratio of 50%; 70 minutes of idle time; 21 hours of HRT; and two cycles per day. The dissolved oxygen at the end of the aerobic cycle is 2-2.5 mg / L, the operating temperature is 25℃, the sludge age is 25-30 days, and the sludge concentration is 2000-3000 mg / L. The raw water is municipal sewage with an ammonia nitrogen concentration of 64.09-84.66 mg / L, a phosphate concentration of 6.24-10.24 mg / L, and a COD / TIN ratio of 3.26-4.24.

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