A method and device for efficient deep denitrification of anammox by 100% drainage ratio pure biofilm section aeration AOA-SBR

Abstract

The present application provides a kind of 100% drainage ratio pure biofilm section aeration AOA-SBR anaerobic ammonia oxidation efficient deep denitrification method and device.Reactor is operated in AOA (anaerobic-aerobic-anoxic) mode, after city domestic sewage is pumped into SBR, anaerobic section stores internal carbon source and releases phosphorus, aerobic section carries out nitrification reaction, with partial short-cut nitrification anaerobic ammonia oxidation and simultaneous short-cut nitrification denitrification process, anoxic zone occurs endogenous denitrification / denitrification phosphorus removal and anaerobic ammonia oxidation process.Through section aeration regulation (three times aerobic and anoxic alternation) make anaerobic ammonia oxidation reaction in full process scale condition occurs.At the same time, rely on the structure of pure filler and set drainage ratio to 100%, improve denitrification and phosphorus removal load and eliminate the influence of last cycle.The present application can realize anaerobic ammonia oxidation efficient deep denitrification without strict inhibition of nitrite oxidizing bacteria, reduce sewage treatment aeration demand and energy consumption.

Description

Technical Field

[0001] This invention relates to a technology and device for efficient and deep denitrification of anaerobic ammonia oxidation in AOA-SBR with 100% wastewater ratio compared to pure biofilm segmented aeration, belonging to the field of wastewater biological treatment and applicable to deep and efficient denitrification of urban domestic sewage. Background Technology

[0002] The excessive influx of nutrients such as nitrogen and phosphorus into natural water bodies leads to the overgrowth of algae, posing a serious threat to aquatic ecosystems. To control eutrophication and protect the aquatic environment, it is essential to efficiently remove these nutrients from wastewater. Traditional biological nitrogen removal processes convert ammonia nitrogen to nitrate nitrogen through nitrification, and then reduce it back to nitrogen gas through denitrification. However, this process is not only energy-intensive but also requires a large external carbon source, significantly increasing the operating costs of wastewater treatment plants. Therefore, the development and application of novel, energy-efficient, and effective nitrogen and phosphorus removal technologies have become an urgent need for solving water pollution problems.

[0003] Anaerobic ammonium oxidation directly converts ammonia nitrogen and nitrite nitrogen into nitrogen gas, providing a highly efficient, purely autotrophic nitrogen removal pathway that removes both types of nitrogen simultaneously. A key aspect of its engineering applications lies in the continuous and stable supply of these two substrates, in conjunction with short-cut nitrification technology (NH4+). + →NO2 - The combined PN / A process can save 60% of aeration and 100% of carbon source. Studies have shown that short-cut nitrification can be achieved through strategies such as low dissolved oxygen, intermittent aeration, and control of residual ammonia nitrogen. In SBR, intermittent aeration with several aeration stops within a cycle requires frequent start-stop of the air pump, which seriously affects its service life. Adjusting intermittent aeration to segmented aeration, i.e., only a few (e.g., three) aeration stops within a cycle, ensures that nitrite-oxidizing bacteria are inhibited by free ammonia for most of the time during the segmented aeration period, which is conducive to the realization of short-cut nitrification. On this basis, it can also provide sufficient substrate for anaerobic ammonia oxidation, and there is no need to strictly control the ammonia nitrogen concentration at the end of the first aerobic stage.

[0004] The anaerobic / anoxic / aerobic (AOA) mode can fully utilize and store the raw water carbon source as an internal carbon source in the anaerobic stage, and undergo endogenous denitrification in the anoxic stage, thus making full use of the raw water carbon source. In traditional SBR systems, the application of the anoxic / anaerobic / aerobic (A2O) mode requires the nitrified liquor from the previous cycle to enter the next cycle for nitrogen removal, and the effluent ratio directly determines the upper limit of the removal rate. However, AOA is different. AOA can remove nitrogen within one cycle and has the potential to increase the load by increasing the effluent ratio to 100%. Simply increasing the effluent ratio may exceed the system's removal capacity, but if combined with staged aeration and anaerobic ammonia oxidation technology, the system's nitrogen removal efficiency can be improved. Based on this, a pure membrane system can be evolved to apply a 100% effluent ratio, thereby greatly increasing the removal load. Furthermore, when the effluent nitrate / nitrite concentration is high, a lower effluent ratio will adversely affect the storage of carbon sources in the next cycle, while the application of a 100% effluent ratio in this invention completely avoids such effects. In this novel process, the aerobic short-cut nitrification and anaerobic ammonia oxidation can save aeration energy consumption, and the segmented aeration does not require strict control of the concentration of residual ammonia nitrogen and nitrite nitrogen. Meanwhile, the anoxic denitrification and anaerobic ammonia oxidation remove nitrogen simultaneously, achieving efficient nitrogen removal through multiple pathways throughout the entire process.

[0005] This invention pumps domestic sewage into an AOA-SBR reactor. In the anaerobic zone, the biofilm stores the raw water's carbon source as an internal carbon source, while polyphosphate-accumulating bacteria release phosphorus anaerobically. Utilizing the segmented aeration characteristic, partial aerobic nitrogen removal is achieved in the aerobic zone through short-cut nitrification coupled with anaerobic ammonium oxidation and endogenous denitrification. In the anoxic zone, the biofilm uses the stored internal carbon source to drive endogenous denitrification, and even denitrification for phosphorus removal. Simultaneously, due to the sufficient ammonia and nitrite nitrogen provided by the segmented aeration, anaerobic ammonium oxidation can occur to achieve nitrogen removal. Throughout the segmented aeration process, multiple pathways synergistically remove nitrogen, ultimately achieving deep nitrogen and phosphorus removal from mainstream urban domestic sewage. Furthermore, as a pure membrane system, the wastewater discharge ratio can be increased to 100%, increasing the treatment load without affecting the treatment effect from the previous cycle. This process has advantages such as low carbon source requirement, low aeration energy consumption, simple operation, low operating cost, and high treatment load. Summary of the Invention

[0006] The purpose of this invention is to provide a technology and device for highly efficient and deep denitrification of 100% wastewater compared to pure biofilm segmented aeration AOA-SBR anaerobic ammonia oxidation. Specifically, the method involves adding only biofilm packing material equipped with short-cut nitrification, endogenous denitrification, and anaerobic ammonia oxidation. Raw water enters the SBR reactor. In the anaerobic section, the biofilm stores the carbon source in the raw water as an endogenous carbon source, while simultaneously releasing phosphorus anaerobically. Aeration is then carried out in segments. In the aerobic section, short-cut nitrification coupled with anaerobic ammonia oxidation and simultaneous short-cut nitrification and denitrification occur, removing some total nitrogen. In the anoxic section, the biofilm utilizes the endogenous carbon source stored in the anaerobic zone to denitrify nitrite and a small amount of nitrate into nitrogen gas and perform denitrification to remove phosphorus. Simultaneously, the remaining ammonia nitrogen and nitrite nitrogen are removed through anaerobic ammonia oxidation. After the final anoxic stage, all wastewater is discharged, ultimately achieving deep and efficient denitrification and phosphorus removal of domestic wastewater.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for efficient deep denitrification of anaerobic ammonium oxidation in AOA-SBR with 100% effluent ratio of pure biofilm segmented aeration, the system used includes an urban domestic sewage raw water tank (1), an influent pump (2), an SBR reactor (3), an electromagnetic ball valve (4), an effluent tank (5), an aeration pump (6), a rotor flow meter (7), an aeration disc (8), a stirrer (9), a stirring paddle (10), a WTW main unit (11), a pH probe (12), and a DO probe (13);

[0009] The method includes the following steps:

[0010] 1) The domestic sewage in the raw sewage tank (1) is transported to the SBR reactor (3) through the inlet pump (2);

[0011] 2) During the operation cycle, the agitator (9) drives the stirring paddle (10) to mix the sewage and biofilm packing in the reactor;

[0012] 3) Intermittently start the aeration pump (6) to provide oxygen to the reactor through the aeration disc (8) and adjust the aeration rate through the rotor flow meter (7);

[0013] 4) The pH value and dissolved oxygen concentration during the reaction process are monitored in real time through the pH probe (12) and DO probe (13) connected to the WTW host (11);

[0014] 5) When the operation cycle ends, open the solenoid ball valve (4) to completely discharge the liquid in the SBR reactor (3) into the outlet tank (5).

[0015] In order to set the wastewater ratio to 100% to increase the treatment load and avoid the residual wastewater from affecting the treatment effect of the next operating cycle, only biofilm packing is set in the SBR reactor (3); the biofilm packing is a pre-cultured packing with short-cut nitrification, endogenous denitrification and anaerobic ammonia oxidation functions, and the packing ratio is not less than 20%.

[0016] To prevent the biofilm packing from becoming inactive or even falling off after complete drainage, the idle time should not exceed 60 minutes. If it must be idle for a long time, the packing should be submerged in water until it is drained before the next water intake.

[0017] Aeration is carried out in stages, with 2-4 stages, which is conducive to the coupling of anaerobic ammonia oxidation throughout the process to improve nitrogen removal efficiency. The aeration time of each stage decreases, and the aeration-stop ratio can be flexibly adjusted. However, there is residual ammonia nitrogen at the end of the last stage of aeration, and the concentration ratio of ammonia nitrogen to nitrite nitrogen is between 1:1 and 1:2.

[0018] Compared with traditional nitration-denitrification processes, this invention has the following advantages:

[0019] 1) Make full use of the carbon source of the raw water. The biofilm stores the internal carbon source in the anaerobic section and undergoes endogenous denitrification in the anoxic section, thereby reducing the treatment cost.

[0020] 2) The residual ammonia nitrogen caused by segmented aeration and the effect of anaerobic ammonia oxidation are conducive to achieving and maintaining short-cut nitrification, saving aeration and eliminating the need for precise control of the residual ammonia nitrogen concentration at the end of the first aerobic stage.

[0021] 3) In the segmented aeration operation mode, there is sufficient ammonia nitrogen and nitrite nitrogen as substrates for anaerobic ammonia oxidation during the entire aeration and shutdown process within a cycle, which can fully remove nitrogen through anaerobic ammonia oxidation;

[0022] 4) The simultaneous occurrence of endogenous denitrification and anaerobic ammonium oxidation, along with the 100% effluent ratio, greatly increases the removal load. The 100% effluent ratio also ensures that the treatment effect is completely unaffected by the effluent from the previous cycle. Attached Figure Description

[0023] Figure 1 A schematic diagram of a system used in a high-efficiency deep nitrogen removal technology and device with 100% wastewater ratio and segmented aeration AOA-SBR anaerobic ammonia oxidation:

[0024] Figure 1 In the middle: 1—Urban domestic sewage raw water tank; 2—Inlet pump; 3—SBR reactor; 4—Solenoid ball valve; 5—Outlet tank; 6—Aeration pump; 7—Rotameter; 8—Aeration disc; 9—Agitator; 10—Agitator paddle; 11—WTW main unit; 12—pH probe; 13—DO probe. Detailed Implementation

[0025] To make the implementation method of the present invention clearer, the invention will be further described in detail with reference to specific embodiments and the accompanying drawings. It should be noted that the following embodiments are merely illustrative examples to help understand the core ideas and technical solutions of the present invention. The scope of protection of the present invention is not limited thereto.

[0026] System startup: Inoculate the SBR reactor (2) with returned sludge from the municipal wastewater treatment plant and PD / A packing material, so that the initial suspended sludge concentration in the reactor is 2000-3000 mg / L, the packing material filling ratio is 20%-30%, and the inoculation ratio is 5%-100%. A higher inoculation ratio results in faster startup. The influent is municipal domestic sewage, with influent COD of 150-250 mg / L and NH4+ of 100 mg / L. + -N: 35-60 mg / L, C / N ratio 3-4; Within one operating cycle, the following sequences are performed sequentially: 1-2 h anaerobic, 1-2 h aerobic, 2-3 h anoxic, 0.5-1 h aerobic, 1-2 h anoxic, 0.5 h aerobic, and 0.5 h anoxic. Initially, the effluent discharge ratio is 50%, and the total hydraulic retention time is 13-22 h. Daily monitoring of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, phosphorus, and COD levels is conducted in the influent, at the end of the anaerobic stage, at the end of the first aerobic stage, at the end of the first anoxic stage, and in the effluent. Additionally, weekly samples are taken from the packing material. Ex-situ batch tests were conducted to determine the nitrification and denitrification performance under reactor operating conditions. If the aerobic nitrite accumulation rate in the first stage exceeded 50%, the short-cut nitrification was successfully started. As the denitrification capacity of the pure packing material improved, the concentration of suspended sludge could be gradually reduced. When the nitrogen removal rate of the pure packing material in the batch test was comparable to that in the reactor, the suspended sludge concentration could be reduced to 0 mg / L. Subsequently, the wastewater ratio was gradually increased to 100% without affecting the nitrogen removal rate as much as possible. Start-up was successful when the wastewater ratio was increased to 100%.

[0027] Process operation after startup: Influent is municipal domestic sewage, influent COD: 150-250 mg / L, NH4 +-N: 35-60mg / L, C / N is 3-4. In one operating cycle, 1-2h anaerobic, 1-2h aerobic, 2-3h anoxic, 0.5-1h aerobic, 1-2h anoxic, 0.5h aerobic and 0.5h anoxic are carried out in sequence, with a drainage ratio of 100% and a total hydraulic retention time of 6.5-11h. After the domestic sewage is pumped into the SBR reactor (2), it first enters the anaerobic stage. The biofilm stores the carbon source of the raw water as an internal carbon source, and polyphosphate-accumulating bacteria release phosphorus anaerobically. Then there is three-stage aeration. Before the last anoxic stage, the system will be in the anaerobic stage. Ammonia nitrogen and nitrite nitrogen coexist. Therefore, in the aerobic section, the system will remove part of the total nitrogen through short-cut nitrification coupled with anaerobic ammonia oxidation and simultaneous short-cut nitrification-denitrification. In the anoxic section, it will remove part of the total nitrogen through endogenous denitrification and anaerobic ammonia oxidation. If operated properly, denitrification can also be carried out to remove phosphorus and achieve phosphate removal. The ammonia nitrogen, nitrite, nitrate nitrogen and phosphorus content of the effluent from the effluent tank (5) are detected, and the final effluent ammonia nitrogen <1.0mg / L, effluent nitrite <0.5mg / L, effluent nitrate nitrogen <1.0mg / L and effluent phosphorus <0.1mg / L are achieved.

[0028] It should be noted that implementation methods not depicted or described in the accompanying drawings or the main text of the specification are all forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the elements above are not limited to the various specific structures, shapes, or methods mentioned in the embodiments, and should not be simply modified or replaced. Any modifications made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for efficient and deep nitrogen removal via AOA-SBR anaerobic ammonia oxidation with 100% wastewater ratio compared to pure biofilm staged aeration, characterized in that: The equipment used includes a raw water tank for urban domestic sewage (1), an inlet pump (2), an SBR reactor (3), an electromagnetic ball valve (4), an outlet tank (5), an aeration pump (6), a rotor flow meter (7), an aeration disc (8), a stirrer (9), a stirring paddle (10), a WTW main unit (11), a pH probe (12), and a DO probe (13). Each running cycle includes the following steps: 1) The domestic sewage in the urban domestic sewage raw water tank (1) is transported to the SBR reactor (3) through the inlet pump (2); 2) When water begins to enter the reactor, the agitator (9) is started simultaneously to drive the agitator (10) to mix the wastewater and biofilm packing material in the reactor; 3) Intermittently start the aeration pump (6) to provide oxygen to the reactor through the aeration disc (8) and adjust the aeration rate through the rotor flow meter (7); the aeration mode is segmented aeration, with 2-4 segments, the aeration time of the last segment is 0.5-1 h shorter than the aeration time of the previous segment, and there is residual ammonia nitrogen at the end of the last aeration segment and the mass concentration ratio of ammonia nitrogen to nitrite nitrogen is 1:1 to 1:2; 4) When the operation cycle ends, turn off the agitator (9) and open the solenoid ball valve (4) to completely drain the liquid in the SBR reactor (3) into the outlet tank (5). The anaerobic section stores the carbon source in the raw water as an internal carbon source and releases phosphorus anaerobically. Then, it is aerated in stages to form an aerobic section and an anoxic section. In the aerobic section, short-cut nitrification coupled with anaerobic ammonium oxidation and simultaneous short-cut nitrification and denitrification occur to remove some of the total nitrogen. In the anoxic section, the biofilm uses the internal carbon source stored in the anaerobic section to denitrify nitrite and a small amount of nitrate into nitrogen gas and remove phosphorus through denitrification. At the same time, the remaining ammonia nitrogen and nitrite nitrogen are removed through anaerobic ammonium oxidation.

2. The method according to claim 1, characterized in that, The initial inoculation ratio is 5%-100%, meaning that the initial inoculation ratio of the packing material is 5%-100% of the total packing material, and the total packing material filling ratio is not less than 20%.

3. The method according to claim 1, characterized in that, The idle time should not exceed 60 minutes; if it must be idle for a long time, the packing should be submerged in water until it is drained before the next water intake.

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