Device and method for enhancing short-cut denitrification coupled anaerobic ammonia oxidation nitrogen and phosphorus removal based on growth cycle of biological membrane

Abstract

The invention relates to a device and a method for nitrogen and phosphorus removal through coupling of enhanced short-cut denitrification and anaerobic ammonia oxidation based on a growth cycle of a biological membrane. The device comprises two up-flow anaerobic sludge beds (UASBs) and a biological aerated filter (BAF). Urban sewage firstly enters the UASB-I (3) to be subjected to the short-cut denitrification coupling anaerobic ammonia oxidation process, domesticated floc sludge is not additionally added in the UASB-I (3), instead, a falling biological membrane flowing back from the UASB-III (6) is utilized to reinforce the formation of granular sludge, and then the denitrification effect of the short-cut denitrification coupling anaerobic ammonia oxidation is improved through the granular sludge; the sewage enters UASB-II, a biological membrane is arranged in the UASB-II, and short-cut denitrification coupled anaerobic ammonia oxidation denitrification is further enhanced; then the sewage enters a BAF (11) to be subjected to an aerobic nitrification process, one part of supernate flows back to the front end of the system, and the other part of the supernate is effluent. Part of carbon sources saved by anaerobic ammonia oxidation can strengthen biological phosphorus removal. According to the invention, the denitrification and dephosphorization effects are improved.

Description

Technical Field

[0001] The invention relates to a device and method for denitrification and phosphorus removal based on enhanced short-range denitrification coupled with anaerobic ammonia oxidation during biofilm growth period, belonging to the technical field of urban sewage treatment and biofilm sewage treatment. Background Art

[0002] Wastewater treatment is a key link in the field of environmental protection. Its importance is self-evident. It is directly related to the purity of water bodies and the balance of the ecosystem, and plays a vital role in ensuring the health and stability of the overall ecological environment. The traditional nitrification and denitrification process is that under aerobic conditions, ammonia nitrogen is converted into nitrate nitrogen by ammonia oxidizing bacteria and nitrite oxidizing bacteria. Under anaerobic conditions, denitrifying bacteria use organic matter as electron donors to reduce nitrate nitrogen or nitrite nitrogen to nitrogen gas.

[0003] In contrast, short-range denitrification technology is an efficient biological denitrification process that avoids the complete reduction of nitrate nitrogen by controlling the denitrification process in the nitrite stage, thereby improving denitrification efficiency and reducing the demand for carbon sources and aeration. Short-range denitrification technology has demonstrated excellent denitrification efficiency and greatly improved the effluent water quality standards due to its streamlined process. In addition, this technology also reduces the amount of sludge generated and alleviates the pressure of subsequent sludge treatment, reflecting its dual advantages in environmental friendliness and economic benefits.

[0004] Anaerobic ammonium oxidation is a process that converts ammonia nitrogen into nitrogen gas under anaerobic conditions, using ammonia nitrogen as an electron donor and nitrate nitrogen or nitrite nitrogen as an electron acceptor. This technology can demonstrate excellent ammonia nitrogen removal capabilities under low temperature and low dissolved oxygen conditions, with a removal rate of more than 85%, significantly improving the efficiency of wastewater treatment. Compared with traditional nitrification and denitrification processes, the oxygen consumption required for anaerobic ammonium oxidation reactions is greatly reduced, only about 35% of the former, thereby significantly reducing the demand for oxygen supply and reducing aeration costs. In addition, anaerobic ammonium oxidation technology exhibits a high degree of compatibility and can be integrated with other wastewater treatment methods, such as biofilm technology, to further improve the overall efficiency of wastewater treatment. The flexibility and integration capabilities of this technology give it a unique competitive advantage in actual application scenarios.

[0005] The short-range denitrification coupled anaerobic ammonium oxidation process is a new type of biological denitrification process, which combines the advantages of short-range denitrification and anaerobic ammonium oxidation to achieve efficient, energy-saving and environmentally friendly sewage treatment. In this context, the present invention proposes a device and method for strengthening the denitrification and phosphorus removal of short-range denitrification coupled anaerobic ammonium oxidation based on the biofilm growth cycle. The method aims to utilize the detached biofilm that flows back to strengthen the formation of granular sludge, and then improve the denitrification effect of short-range denitrification coupled anaerobic ammonium oxidation through granular sludge, avoiding the consumption of nitrite by adding flocculent sludge. Summary of the invention

[0006] A device for strengthening short-range denitrification coupled with anaerobic ammonium oxidation denitrification and phosphorus removal based on a biofilm growth cycle, wherein a water inlet pipe (1) is connected to the bottom of a UASB-Ι (3), and urban sewage enters therefrom and undergoes a short-range denitrification coupled with anaerobic ammonium oxidation reaction in the UASB-Ι (3); the UASB-Ι (3) is connected to a UASB-Ⅱ (6) via a peristaltic pump Ι (4), so that the sewage enters the UASB-Ⅱ (6); a biological filler (5) is arranged in the UASB-Ⅱ (6), on which a biofilm grows; the UASB-Ⅱ (6) is connected to the UASB-Ι (3) via a peristaltic pump Ⅱ (7), so that part of the detached biofilm carried by the return water after the biofilm detaches is returned to the UASB-Ι (3); the UASB-Ⅱ (6) provides the detached biofilm for the UASB-Ι (3), provides seed sludge for forming granular sludge (2), and strengthens granulation. UASB-Ⅱ(6) is connected to BAF(11) through peristaltic pump III(8), so that the effluent of UASB-Ⅱ(6) enters BAF(11), which is provided with aerobic filler(10) and aeration plate(9), and the aeration plate(9) is connected to aeration pump(12). Aerobic autotrophic nitrifying bacteria grow on the filler, and nitrification occurs under aeration conditions. BAF aerated biological filter(11) is connected to UASB-Ι(3) through peristaltic pump IV(13), and the supernatant therein is refluxed to UASB-Ι(3) to provide nitrate nitrogen thereto. BAF aerated biological filter(11) is connected to the outside through an outlet pipe(14), and the effluent of the system is discharged.

[0007] By using the detached biofilm instead of the externally domesticated floc sludge, the biofilm in UASB-Ⅱ can be used to granulate UASB-Ι through reflow. Direct use of the detached biofilm avoids the heterotrophic denitrification that may be caused by the externally cultivated floc sludge, reduces nitrite consumption, and thus optimizes the reaction effect of short-range denitrification coupled with anaerobic ammonium oxidation, and the formation of granular sludge can be enhanced based on the reactor setting.

[0008] Both UASB-Ⅱ and BAF aerated biological filters need to be equipped with biological fillers. The biological fillers in UASB-Ⅱ provide anoxic microenvironment for denitrification functional microorganisms, which is conducive to the coordinated growth of denitrifying bacteria and anaerobic ammonia oxidizing bacteria; the fillers in BAF grow aerobic autotrophic nitrifying bacteria, which undergo nitrification under aeration conditions. The filling ratio of biological fillers is 45%-65%, and the specific surface area is 400m 2 / m 3 -600m 2 / m 3 , density is 0.96-1.00g / cm 3 .

[0009] The raw water may be sewage that has passed through structures such as the water inlet well, regulating tank, coarse screen, fine screen, grit tank, and primary sedimentation tank in sequence, or it may be sewage that has passed through some of the above structures.

[0010] Its technical principles and characteristics:

[0011] 1) The principle of this patent is based on the growth cycle of biofilm, and the formation of granular sludge is enhanced by shedding biofilm. It is mainly achieved through two UASB reactors: both reactors carry out short-range denitrification coupled with anaerobic ammonia oxidation. There is biological filler in UASB-Ⅱ, and biofilm grows on the filler. After the biofilm falls off, it is returned to UASB-Ⅰ to provide biofilm, providing seed mud for the formation of granular sludge, thereby enhancing granulation.

[0012] 2) Using detached biofilm instead of adding domesticated floc sludge, the biofilm in UASB-II can be granulated for UASB-Ι by refluxing. Adding floc sludge will undergo heterotrophic denitrification, thereby consuming part of the important substrate nitrite of anaerobic ammonium oxidation reaction, affecting the overall denitrification effect. Using detached biofilm can avoid this process and increase the abundance of anaerobic ammonium oxidizing bacteria.

[0013] 3) The biological filler in UASB-Ⅱ is cylindrical and has a specific surface area of ​​400m 2 / m 3 ~600m 2 / m 3 The porosity is greater than 95%, providing an anoxic microenvironment for denitrification microorganisms, which is conducive to the coordinated growth of denitrifying bacteria and anaerobic ammonia oxidizing bacteria. Aerobic autotrophic nitrifying bacteria grow in the filler of BAF, and nitrification occurs under aeration conditions. The filling ratio of biological filler is 45%-65%, and the specific surface area is 400m 2 / m 3 -600m 2 / m 3 , density is 0.96-1.00g / cm 3 .

[0014] 4) The filling ratio of biological filler in UASB-Ⅱ is controlled between 25-45%, and the filling ratio of aerobic filler in BAF aerated biological filter is controlled between 45-65% to ensure the growth conditions of microorganisms.

[0015] 5) This method not only improves the denitrification effect, but also enhances biological phosphorus removal due to the partial carbon source saved by anaerobic ammonium oxidation, thus achieving multiple sewage treatment goals.

[0016] 6) Through the short-range denitrification coupled with anaerobic ammonium oxidation process, efficient, energy-saving and environmentally friendly sewage treatment is achieved, reducing operating costs and environmental burden.

[0017] The present invention has the following advantages:

[0018] 1) High abundance of anaerobic ammonium oxidizing bacteria: By using the detached biofilm instead of the externally domesticated flocculent sludge, the biofilm in UASB-Ⅱ can be granulated for UASB-Ι by refluxing. The externally added flocculent sludge will undergo heterotrophic denitrification, thereby consuming part of the important substrate nitrite of the anaerobic ammonium oxidation reaction, affecting the overall denitrification effect. The use of flocculent sludge in the detached biofilm can avoid this process and increase the abundance of anaerobic ammonium oxidizing bacteria, thereby optimizing the reaction effect of short-range denitrification coupled with anaerobic ammonium oxidation, and the formation of granular sludge can be enhanced based on the setting of the reactor.

[0019] 2) Save carbon source: Part of the carbon source is saved through the anaerobic ammonium oxidation process, and the saved carbon source is used to enhance biological phosphorus removal, thereby improving resource utilization efficiency and reducing operating costs.

[0020] 3) Improve denitrification efficiency: Short-range denitrification technology controls the conditions so that the denitrification process only reduces nitrate nitrogen to nitrite nitrogen, but not completely to nitrogen gas, thereby accumulating nitrite. This intermediate product nitrite is then converted into nitrogen gas together with ammonia nitrogen as an electron acceptor in the anaerobic ammonium oxidation process, achieving efficient denitrification. This process not only saves carbon source and aeration energy consumption, but also reduces greenhouse gas emissions and improves the total nitrogen removal rate.

[0021] 4) Low residual sludge production: The system reaction process is partial autotrophic denitrification. The removal of 1 mol of ammonia nitrogen only produces 3g of organisms. The sludge production is effectively reduced, which is beneficial to reducing the sludge disposal cost and also reduces the operating cost.

[0022] 5) Compact layout and small footprint: It not only improves the denitrification efficiency, but also improves the effluent quality, meeting more stringent environmental protection requirements. At the same time, the high load characteristics of UASB are utilized to save floor space, which is conducive to enhancing market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a device for denitrification and phosphorus removal based on enhanced short-range denitrification coupled with anaerobic ammonia oxidation based on biofilm growth cycle.

[0024] Specifically: 1-water inlet pipeline; 2-UASB-Ι granular sludge; 3-UASB-Ι; 4-peristaltic pump Ι; 5-UASB-Ⅱ biological filler; 6-UASB-Ⅱ; 7-peristaltic pump Ⅱ; 8-peristaltic pump Ⅲ; 9-aeration plate; 10-aerobic filler; 11-BAF aerated biological filter; 12-aeration pump; 13-peristaltic pump Ⅳ; 14-water outlet pipeline. DETAILED DESCRIPTION

[0025] Combination Figure 1 , describe the embodiments of the present invention in detail:

[0026] 1) Start the system: The sewage first enters UASB-1 for short-range denitrification coupled with anaerobic ammonium oxidation, and then enters UASB-Ⅱ, where short-range denitrification coupled with anaerobic ammonium oxidation also occurs. Part of the effluent is returned to UASB-1 through a peristaltic pump to strengthen the formation of granular sludge, and part of the effluent enters the BAF aerated biological filter for aerobic nitrification, and the supernatant is returned to UASB-1. The filling ratio of the biological filler in UASB-Ⅱ is controlled between 25-45%, and the filling ratio of the biological filler in the BAF aerated biological filter is controlled between 45-65%. The biological filler is cylindrical with a specific surface area of ​​400-600m 2 / m 3 , porosity greater than 95%.

[0027] 2) Main operating parameters:

[0028] ①Hydraulic retention time (HRT):

[0029] UASB-I: The designed hydraulic retention time is 4 hours to ensure sufficient time for short-range denitrification coupled with anaerobic ammonium oxidation.

[0030] UASB-II: The designed hydraulic retention time is 6 hours to further enhance the denitrification effect.

[0031] BAF aerated biological filter: The designed hydraulic retention time is 2 hours to complete aerobic nitrification.

[0032] ②Dissolved oxygen (DO) control:

[0033] UASB-I and UASB-II: Dissolved oxygen is controlled below 0.5 mg / L to promote anaerobic ammonium oxidation.

[0034] BAF aerated biological filter: dissolved oxygen is controlled at 2.5-3.5 mg / L to ensure aerobic nitrification process.

[0035] ③Reflux ratio:

[0036] The return ratio from UASB-II to UASB-I was 100% to enhance the formation of granular sludge.

[0037] The reflux ratio from BAF to supernatant to UASB-I was 200% to provide sufficient nitrate nitrogen.

[0038] ④Biological filler parameters:

[0039] UASB-Ⅱ: The biological filler is cylindrical and has a specific surface area of ​​400m 2 / m 3 ~600m 2 / m 3The porosity is greater than 95%, which provides an anoxic microenvironment for denitrification functional microorganisms, is conducive to the coordinated growth of denitrifying bacteria and anaerobic ammonia oxidizing bacteria, and the filling ratio is controlled between 25-45%.

[0040] BAF aerated biological filter: Aerobic autotrophic nitrifying bacteria grow in the filler of BAF, and nitrification occurs under aeration conditions. The filling ratio of biological filler is 45%-65%, and the specific surface area is 400m 2 / m 3 -600m 2 / m 3 , density is 0.96-1.00g / cm 3 .

Claims

1. A device for denitrification and phosphorus removal based on enhanced short-range denitrification coupled with anaerobic ammonium oxidation based on biofilm growth cycle, characterized in that: The water inlet pipe (1) is connected to the bottom of UASB-Ι (3), and UASB-Ι (3) is connected to UASB-Ⅱ (6) through a peristaltic pump Ι (4), so that sewage enters UASB-Ⅱ (6), and biological fillers (5) are arranged in UASB-Ⅱ (6). UASB-Ⅱ (6) is connected to UASB-Ι (3) through a peristaltic pump Ⅱ (7), and UASB-Ⅱ (6) provides detached biofilm for UASB-Ι (3). UASB-Ⅱ (6) The peristaltic pump III (8) is connected to the BAF (11), so that the effluent of the UASB-II (6) enters the BAF (11), in which an aerobic filler (10) and an aeration plate (9) are placed. The aeration plate (9) is connected to the aeration pump (12); the BAF aerated biological filter (11) is connected to the UASB-Ι (3) through the peristaltic pump IV (13), and the supernatant therein is returned to the UASB-Ι (3). The BAF aerated biological filter (11) is connected to the outside through the effluent pipeline (14).

2. A method for applying the device as claimed in claim 1, characterized in that: Start the system: The sewage first enters UASB-Ι for short-range denitrification coupled with anaerobic ammonium oxidation, and then enters UASB-Ⅱ. Part of the effluent is returned to UASB-Ι through a peristaltic pump to strengthen the formation of granular sludge, and part of the effluent enters the BAF aerated biological filter for aerobic nitrification, and the supernatant is returned to UASB-Ι; Run parameters: ①Hydraulic retention time (HRT): UASB-I: Design hydraulic retention time is 4 hours; UASB-II: Design hydraulic retention time is 6 hours; BAF aerated biological filter: the designed hydraulic retention time is 2 hours; ②Dissolved oxygen (DO) control: UASB-I and UASB-II: dissolved oxygen is controlled below 0.5 mg / L; BAF aerated biological filter: dissolved oxygen is controlled at 2.5-3.5 mg / ; ③Reflux ratio: Reflux ratio from UASB-II to UASB-I: 100%; Reflux ratio from BAF to supernatant to UASB-I: 200%; ④Biological filler parameters: UASB-Ⅱ: biological filler with a specific surface area of ​​400m 2 / m 3 ~600m 2 / m 3 , porosity greater than 95%, and filling ratio controlled between 25-45%; BAF aerated biological filter: The biological filler filling ratio in BAF is 45%-65%, and the specific surface area is 400m 2 / m 3 -600m 2 / m 3 , density is 0.96-1.00g / cm 3 .

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