Rapid concentration and highly efficient denitrification of anaerobic ammonium oxidation sludge using municipal wastewater activated sludge

Abstract

The present invention relates to a method for rapidly concentrating anaerobic ammonia oxidation sludge and performing high-efficiency denitrification by using municipal sewage activated sludge, which belongs to the field of water environment recovery and regeneration, and achieves rapid concentration of anaerobic ammonia oxidation sludge and high-efficiency denitrification of anaerobic ammonia oxidation by inoculating activated sludge in a continuous flow biofilm reactor.SOLUTION: The reactor consists of a continuous flow biofilm device and a secondary sedimentation basin. A polyethylene brush filler is suspended in the chamber of the continuous flow biological membrane device, a mechanical stirrer is provided, and the polyethylene brush filler is suspended in the secondary sedimentation basin. No aeration device is arranged in the reactor, and the return sludge of the secondary sedimentation basin is returned to the water inlet by a peristaltic pump. By gradually increasing the concentrations of ammonium nitrogen and nitrite nitrogen in the influent water of the reactor, the hydraulic retention time of the reactor is reduced, the rapid concentration of anaerobic ammonium oxidation sludge is realized, and the load of anaerobic ammonium oxidation denitrification of the reactor is rapidly increased.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention belongs to the field of wastewater treatment technology, and relates to a method for rapid concentration of anaerobic ammonium oxidation sludge using activated sludge from municipal sewage and a method for highly efficient denitrification. [Background technology]

[0002] Conventional biological denitrification technologies for urban wastewater generally employ nitrification and denitrification techniques. Under aerobic conditions, nitrifying bacteria use oxygen to oxidize ammonia nitrogen to nitrate nitrogen. Under anaerobic conditions, denitrifying bacteria use a carbon source to reduce nitrate to nitrogen. Conventional biological denitrification processes suffer from carbon source shortages, high aeration consumption, and large amounts of excess sludge. Anaerobic ammonium oxidation biological denitrification technology uses anaerobic ammonium oxidizing bacteria to convert ammonia nitrogen and nitrite nitrogen to nitrogen and small amounts of nitrate under anaerobic conditions, offering the advantages of reduced energy consumption, carbon resource savings, and reduced sludge production. Anaerobic ammonium oxidizing bacteria have low cell yields, a generation time of approximately 11 days, and sensitivity to environmental changes, resulting in long start-up times and low denitrification loads. In recent years, researchers have reported that anaerobic ammonium oxidation biofilms and anaerobic ammonium oxidation granular sludge can increase reactor sludge retention and accelerate the start-up of anaerobic ammonium oxidation processes. However, anaerobic ammonium oxidation biofilm processes struggle to efficiently block anaerobic ammonium oxidation flocculated sludge during the initial start-up phase, resulting in long biofilm thickening times. Furthermore, anaerobic ammonium oxidation biofilm processes suffer from poor substrate mass transfer and low reactor denitrification loads. Anaerobic ammonium oxidation biofilm processes based on biological filters suffer from poor substrate mass transfer and susceptibility to clogging. Anaerobic ammonium oxidation granular sludge processes require long granule formation times, resulting in large amounts of highly activated granular sludge floating, which can accumulate on the top of the reactor or be washed away with the floodwater, reducing the reactor's denitrification load. Municipal wastewater treatment processes generate large amounts of activated sludge, so developing methods for rapid thickening and highly efficient denitrification of anaerobic ammonium oxidation sludge using municipal wastewater activated sludge is of great importance. Summary of the Invention

[0003] The present invention relates to a method for rapid concentration of anaerobic ammonium oxidation sludge and high-efficiency denitrification of anaerobic ammonium oxidation by inoculating activated sludge in a continuous-flow biofilm device. The present invention relates to a method for rapid concentration and high-efficiency denitrification of anaerobic ammonium oxidation sludge using municipal wastewater activated sludge, and the steps are as follows: (1) The reactor consists of a continuous-flow biofilm device and a secondary sedimentation tank. The continuous-flow biofilm device has an effective volume of 54 L and is divided into six partitions by vertical baffle plates, each with a volume of 9 L. The water flows up and down along the baffle plates, forming sequentially connected reaction partitions. The secondary sedimentation tank is a vertical flow type, with water entering at the center and discharging at the periphery, and has an effective volume of 22 L. (2) Polyethylene brush-like filler is suspended within the partition of the continuous flow biofilm device, and the filling rate of the filler is 70%. A mechanical agitator is installed within the partition, and the agitator blade is positioned below the brush-like filler to avoid collision with the brush-like filler. The rotation speed of the agitator blade is 200 r / min. (3) Polyethylene brush-like filler is suspended inside the secondary sedimentation tank, with a filler filling rate of 70%. A wave-making pump is installed at the bottom of the secondary sedimentation tank, and its operation mode is set to intermittent operation mode (on for 3 minutes / off for 57 minutes), to prevent flocculated sludge from accumulating at the bottom of the secondary sedimentation tank. (4) The inoculated sludge is the circulating activated sludge from the secondary sedimentation tank of the wastewater plant, with an inoculation volume of 35 L and a sludge concentration of 14,000 mg / L. (5) The input water to the reactor is artificial wastewater, and the specific components of the input water are NH4 + -N(NH4Cl): Concentration should be adjusted as needed. NO2 - -N (NaNO2): Concentration should be adjusted as needed. NH4 + -N and NO2 -The -N concentration ratio was 1:1-1.32, KH2PO4: 5mg / L, CaCl2: 8mg / L, MgSO4: 32mg / L, and 1mL of trace elements was contained per 1L of inlet water. The concentrations of trace elements were Na2-EDTA: 50g / L, FeSO4·7H2O: 5g / L, CoSO4·5H2O: 1.9g / L, MnCl2·4H2O: 5.1g / L, CuSO4·5H2O: 1.6g / L, ZnSO4·7H2O: 5g / L, and NaMoO4·2H2O: 1.1g / L. (6) The temperature in the continuous flow biofilm device and secondary sedimentation tank is 24-26°C. No aeration device is installed in the reactor, and the reflux sludge from the secondary sedimentation tank is returned to the inlet by a peristaltic pump, with a flow rate of 9.1 L / h. (7) In the continuous flow biofilm system, the inlet ammonia nitrogen concentration is increased from 25 mg / L to 100 mg / L, the inlet nitrite nitrogen concentration is increased from 30 mg / L to 125 mg / L, and the hydraulic retention time is gradually adjusted from 7.3 h to 2.4 h. [Brief explanation of the drawings]

[0004] [Figure 1] FIG. 1 is a schematic diagram of a reactor. [Figure 2] The concentrations of ammonia nitrogen and nitrite nitrogen in the inlet and outlet water of the reactor. [Figure 3] The reactor inlet ammonia nitrogen loading, inlet nitrite nitrogen loading, and hydraulic retention time. [Figure 4] The removal rates of ammonia nitrogen and nitrite nitrogen in the reactor. [Figure 5] FIG. 1 is a graph showing the changes in ammonia nitrogen and nitrite nitrogen concentrations in the reactor on the 141st day. DETAILED DESCRIPTION OF THE INVENTION

[0005] 1. The reactor apparatus is shown in Figure 1. 2. The operating procedure for adopting the above method is as follows: (1) Reactor: As shown in Figure 1, the reactor consisted of a continuous-flow biofilm device and a secondary sedimentation tank. The continuous-flow biofilm device had an effective volume of 54 L and was divided into six partitions by vertical baffle plates, each with a volume of 9 L. Water flowed up and down along the baffle plates, forming sequentially connected reaction partitions. The secondary sedimentation tank was a vertical flow-type tank with water entering the center and discharging to the periphery, resulting in an effective volume of 22 L. Polyethylene brush fillers were suspended within the partitions of the continuous-flow biofilm device, with a filler filling rate of 70%. A mechanical agitator was installed within the partition, with the agitator blades positioned below the brush fillers to avoid collisions with the brush fillers. The agitator blade rotation speed was 200 r / min. Polyethylene brush-like filler was suspended inside the secondary sedimentation tank, with a filler filling rate of 70%. A wave-making pump was installed at the bottom of the secondary sedimentation tank, and its operation mode was set to intermittent operation mode (3 minutes on / 57 minutes off) to prevent flocculated sludge from accumulating at the bottom of the secondary sedimentation tank. (2) The inoculated sludge was the circulating activated sludge from the secondary sedimentation tank of a wastewater treatment plant. The inoculation volume was 35 L and the sludge concentration was 14,000 mg / L. (3) Reactor input water: Artificial simulated wastewater is used, and the specific input water components are NH4 + -N(NH4Cl): Concentration should be adjusted as needed. NO2 - -N (NaNO2): Concentration should be adjusted as needed. NH4 + -N and NO2 - The -N concentration ratio was 1:1-1.32, KH2PO4: 5mg / L, CaCl2: 8mg / L, MgSO4: 32mg / L, and 1mL of trace elements was contained per 1L of inlet water. The concentrations of trace elements were Na2-EDTA: 50g / L, FeSO4·7H2O: 5g / L, CoSO4·5H2O: 1.9g / L, MnCl2·4H2O: 5.1g / L, CuSO4·5H2O: 1.6g / L, ZnSO4·7H2O: 5g / L, and NaMoO4·2H2O: 1.1g / L. (4) Reactor operating parameters: The temperature in the continuous-flow biofilm device and secondary sedimentation tank was 24-26°C. No aeration device was installed in the reactor, and a peristaltic pump was used to return the reflux sludge from the secondary sedimentation tank to the inlet, with a flow rate of 9.1 L / h. In the continuous-flow biofilm device, the inlet ammonia nitrogen concentration was increased from 25 mg / L to 100 mg / L, and the inlet nitrite nitrogen concentration was increased from 30 mg / L to 125 mg / L. The hydraulic retention time was gradually adjusted from 7.3 h to 2.4 h. (5) Reactor operating conditions: The reactor operation was divided into two stages: Stage 1 (1-70d), which was an anaerobic ammonium oxidizing biofilm enrichment stage, and Stage 2 (71-141d), which was an anaerobic ammonium oxidizing denitrification load rapid increase stage.

[0006] Stage 1: From day 1 to day 34, the reactor inlet ammonia nitrogen concentration was 25-30 mg / L, the inlet nitrite nitrogen concentration was 30-40 mg / L, and the hydraulic retention time was 7.3 h. From day 20, the reactor outlet ammonia nitrogen and nitrite nitrogen concentrations gradually decreased. By day 34, the reactor outlet ammonia nitrogen and nitrite nitrogen concentrations were 4.8 and 5.0 mg / L, respectively, the ammonia nitrogen removal rate and nitrite nitrogen removal rate were 82.6% and 85.3%, respectively, and the ammonia nitrogen removal load and nitrite nitrogen removal load were 0.07 kgN / (m 3 ·d) and 0.10KgN / (m 3 From the 35th to the 70th day, the concentrations of ammonia nitrogen and nitrite nitrogen in the reactor inlet water were gradually increased. By the 70th day, the concentrations of ammonia nitrogen and nitrite nitrogen in the reactor inlet water were 92.7 mg / L and 118.9 mg / L, respectively, and the concentrations of ammonia nitrogen and nitrite nitrogen in the reactor outlet water were 0.7 mg / L and 9.9 mg / L, respectively. The ammonia nitrogen removal rate and nitrite nitrogen removal rate were 99.2% and 91.7%, respectively, and the ammonia nitrogen removal load and nitrite nitrogen removal load were 0.34 kgN / (m 3 ·d) and 0.40KgN / (m 3 ·d).

[0007] Stage 2: The reactor inlet ammonia nitrogen concentration was 80-100 mg / L, the inlet nitrite nitrogen concentration was 100-125 mg / L, and the hydraulic retention time decreased from 9.7 h to 2.4 h. By the 141st day, the reactor hydraulic retention time was 2.4 h, there was no flocculated sludge discharge during the inlet, the inlet ammonia nitrogen and nitrite nitrogen concentrations were 5.7 and 21.1 mg / L, respectively, the ammonia nitrogen removal rate and nitrite nitrogen removal rate were 93.2% and 80.2%, respectively, and the ammonia nitrogen removal load and nitrite nitrogen removal load were 0.79 kgN / (m 3 ·d) and 0.85KgN / (m 3 d). From Figure 5, on the 141st day, the nitrite nitrogen concentrations in the first, second, third, fourth, fifth, sixth, and secondary sedimentation tanks were 32.3 mg / L, 30.3 mg / L, 27.5 mg / L, 26.4 mg / L, 24.5 mg / L, 23.0 mg / L, and 21.1 mg / L, respectively, and the nitrite nitrogen concentration in the reactor was less than 100 mg / L.

[0008] The high-efficiency anaerobic ammonium oxidizing bacteria concentration device proposed in this study can rapidly concentrate anaerobic ammonium oxidizing bacteria, effectively avoiding the loss of anaerobic ammonium oxidizing sludge, and achieving a high anaerobic ammonium oxidizing denitrification load. The underlying mechanisms are as follows: 1) This study adds polyethylene brush-like fillers to the continuous-flow reactor and biofilm reactor to provide a settling site for flocculated sludge. The flocculated sludge from the secondary settling tank is transported to the reactor by a sludge reflux pump. This shortens the hydraulic retention time to 2.4 hours, resulting in almost no flocculated sludge in the outflow and promoting rapid sludge adhesion to the biofilm. 2) The continuous-flow reactor is equipped with a mechanical agitator to enhance the perturbation effect of water flow, enhancing mass transfer between the biofilm and the substrate, and increasing the reactor's denitrification load. 3) By the 141st day, a large amount of anaerobic ammonium-oxidizing granular sludge had attached and grown to the biofilm, forming a variety of sludge structures, including flocculated sludge, biofilm, and granular sludge. This significantly increased the amount of anaerobic ammonium-oxidizing sludge in the reactor, strengthening the resistance of anaerobic ammonium-oxidizing bacteria to unfavorable environments and high nitrite nitrogen concentrations, and improving the anaerobic ammonium oxidation and denitrification load. 4) High nitrite nitrogen concentrations and short hydraulic retention times are operational methods for increasing the nitrogen load in the reactor inlet water, but nitrite nitrogen concentrations above 100 mg / L suppress the anaerobic ammonium oxidation activity of the sludge. The continuous flow reactor of the present invention has an inlet water nitrite nitrogen concentration of up to 100-125 mg / L, and a reflux pump outside the reactor can dilute the inlet water nitrite nitrogen concentration. The reactor biofilm has good anaerobic ammonia oxidation performance, and when the hydraulic retention time is 2.4 hours, the nitrite nitrogen concentration in the reactor is lower than 100 mg / L, which effectively prevents the inhibition of anaerobic ammonia oxidizing bacteria caused by high nitrite nitrogen concentration. (6) Other types of changes and modifications can be made based on the above principles, and these changes and modifications are within the scope of the present invention. [Explanation of symbols]

[0009] 1 inlet pump, 2 continuous flow biofilm devices, 3 secondary settling tanks; 4 Secondary settling tank overflow, 5 sludge return pump, 6 wave pumps, 7 needle-shaped plastic filler, 8 Mechanical Stirrer

Claims

1. 1) The reactor consists of a continuous flow biofilm device and a secondary sedimentation tank. The effective volume of the continuous flow biofilm device is 54L, and is divided into six partitions by vertical baffle plates, with the volume of each partition being 9L. The water flows up and down along the baffle plates, forming reaction partitions connected in series. The secondary sedimentation tank is a vertical flow type, with water entering the center and discharging from the periphery, and the effective volume is 22L. 2) Polyethylene brush-like filler is suspended in the partition of the continuous flow biofilm device, the filling rate of the filler is 70%, a mechanical agitator is installed in the partition, the agitator blade is located under the brush-like filler to avoid collision with the brush-like filler, and the rotation speed of the agitator blade is 200 r / min; 3) Polyethylene brush-like filler is suspended in the secondary sedimentation tank, and the filling rate of the filler is 70%. A wave pump is installed at the bottom of the secondary sedimentation tank, and its operation mode is set to intermittent operation mode (3 minutes on / 57 minutes off) to prevent flocculated sludge from accumulating at the bottom of the secondary sedimentation tank. 4) The inoculation sludge is the circulating activated sludge from the secondary sedimentation tank of the wastewater treatment plant, the inoculation volume is 35 L, and the sludge concentration is 14,000 mg / L. 5) The temperature in the continuous flow biofilm device and the secondary sedimentation tank is 24-26°C, no aeration device is installed in the reactor, and the reflux sludge in the secondary sedimentation tank is returned to the inlet by a peristaltic pump, and the flow rate is 9.1 L / h; 6) In the continuous flow biofilm device, the inlet water ammonia nitrogen concentration is increased from 25 mg / L to 100 mg / L, the inlet water nitrite nitrogen concentration is increased from 30 mg / L to 125 mg / L, and the hydraulic retention time is gradually adjusted from 7.3 h to 2.4 h, where, from day 1 to day 34, the inlet water ammonia nitrogen concentration of the reactor is 25-30 mg / L, the inlet water nitrite nitrogen concentration is 30-40 mg / L, and the hydraulic retention time is 7.3 h. A method for rapid concentration and highly efficient denitrification of anaerobic ammonium oxidation sludge using activated sludge from municipal sewage, characterized by the following:

2. The inlet water to the reactor is artificial simulated wastewater, and the specific inlet water components are NH ４ ＋ -N(NH ４ Cl): concentration is added as needed, NO ２ － -N(NaNO ２ ): concentration should be added as needed, NH ４ ＋ -N and NO ２ － -N concentration ratio: 1:1 to 1.32, KH ２ P.O. ４ :5mg / L, CaCl ２ :8mg / L, MgSO ４ : 32 mg / L, contains 1 mL of trace elements per 1 L of inlet water, and the concentration of trace elements is Na ２ -EDTA: 50g / L, FeSO ４ ・7H ２ O: 5g / L, CoSO ４ ・5H ２ O: 1.9g / L, MnCl ２ ・4H ２ O: 5.1g / L, CuSO ４ ・5H ２ O: 1.6g / L, ZnSO ４ ・7H ２ O: 5g / L, NaMoO ４ ・2H ２ O: 1.1 g / L 2. A method for rapid concentration and highly efficient denitrification of anaerobic ammonium oxidizing sludge using municipal sewage activated sludge according to claim 1.

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