A method for deep nitrogen and phosphorus removal by continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm

Abstract

The present invention discloses a method for deep denitrification and phosphorus removal using continuous-flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilms. The method comprises: inoculating a deep denitrification and phosphorus removal device with flocculent, fully nitrifying sludge at a concentration of 2500 to 4500 mg / L, then filling it with sewage, causing the flocculent, fully nitrifying sludge to self-aggregate into short-cut nitrifying granular sludge, initiating sludge circulation, mixing the sewage and granular sludge in a transient mixing tube, and then entering a first mixing zone. The accumulated nitrite is monitored. When short-cut nitrification is disrupted, an alkali solution, ammonia, and a NOB inhibitor are added to the second mixing zone. The DO concentrations in the aerobic zone and the anaerobic ammonium oxidation zone are monitored and controlled to reduce the nitrite concentration to below 0.8 mg / L. This method achieves continuous-flow municipal sewage short-cut nitrification granular sludge, and achieves deep denitrification and phosphorus removal coupled with short-cut nitrification and denitrification of the granular sludge and anaerobic ammonium oxidation, overcoming the technical bottlenecks of difficult continuous-flow granular sludge cultivation, difficult implementation of short-cut nitrifying granular sludge, and difficult implementation of coupled denitrification of granular sludge and anaerobic ammonium oxidation.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and more specifically, relates to a method for deep denitrification and phosphorus removal by coupling self-enrichment of granular sludge with autotrophic biofilm in continuous-flow urban sewage. Background Art

[0002] Currently, phosphorus in wastewater can be efficiently removed through chemical methods, while nitrogen removal primarily relies on biological methods. Efficient nitrogen removal is an international challenge in water pollution control. Traditional nitrification and denitrification processes suffer from technical issues such as high aeration energy consumption, reliance on external carbon sources, and high sludge production. These issues lead to complex wastewater treatment processes, low efficiency, difficulty meeting standards, and high construction and operating costs. This represents a "high-cost" wastewater treatment method. Therefore, the development and widespread application of low-energy, high-efficiency wastewater denitrification technologies is urgently needed.

[0003] The anaerobic ammonium oxidation (ANAMMOX) process represents a significant breakthrough in both concept and technology for the traditional nitrification-denitrification process. ANAMMOX bacteria utilize nitrite as an electron acceptor to oxidize ammonia nitrogen to produce nitrogen gas, utilizing inorganic carbon as a carbon source, rather than requiring organic matter as a carbon source, thereby achieving autotrophic biological denitrification. Compared to traditional biological denitrification, short-range nitrification / ANAMMOX autotrophic denitrification can reduce aeration volume by 60% and carbon source dosage by 100%. Currently, ANAMMOX has been successfully applied on a large scale to treat high-ammonia nitrogen wastewaters, such as sludge digestate, landfill leachate, aquaculture wastewater, and pharmaceutical wastewater. However, the practical application of this technology in municipal wastewater still faces numerous technical challenges that require overcoming.

[0004] Aerobic granular sludge is a microbial aggregate formed under specific conditions. Compared with traditional activated sludge, aerobic granular sludge has a dense structure, a sedimentation rate that is 5 to 10 times that of ordinary activated sludge, saves 20% to 70% of floor space, and can increase water load by more than 20%; the abundance of functional bacteria is increased by 2 to 3 times, the biochemical reaction efficiency is high, the shock load resistance is strong, and the effluent quality is good; the process flow is short, and energy consumption is reduced by 20% to 35%; the simultaneous denitrification and phosphorus removal effects are good, and drug consumption is saved by 60% to 80%; it is suitable for treating both domestic sewage and industrial wastewater; currently, aerobic granular sludge technology has been applied in the SBR process of urban sewage treatment plants, but the difficulties of this technology in continuous flow urban sewage treatment have not been overcome. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and provide a method for deep denitrification and phosphorus removal by coupling self-enrichment of granular sludge from continuous-flow urban sewage with autotrophic biofilm, so as to solve the problems of unstable operation, poor effluent quality, high operating costs, low treatment load and large greenhouse gas emissions of existing urban sewage devices.

[0006] In order to achieve the above object, the present invention provides a method for deep denitrification and phosphorus removal by continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm, comprising:

[0007] The first mixing zone, the second mixing zone, the aerobic zone, and the anaerobic ammonium oxidation zone are connected in sequence by overflow to form a deep denitrification and phosphorus removal device. The anaerobic ammonium oxidation zone is provided with an anaerobic ammonium oxidation biofilm. The overflow of the deep denitrification and phosphorus removal device is connected to a sedimentation tank. The sedimentation tank is connected to the first mixing zone through an instantaneous mixing pipe to form a sludge circulation.

[0008] S1. The deep denitrification and phosphorus removal device is inoculated with flocculent full-process nitrification sludge at a concentration of 2500~4500mg / L and then filled with sewage to make the flocculent full-process nitrification sludge self-aggregate into short-process nitrification granular sludge with an average particle size of 120-250μm and SVI=50~75;

[0009] The effluent from the deep denitrification and phosphorus removal device is stable for 15 consecutive days, with effluent ammonia nitrogen below 1.5 mg / L, effluent TN below 7 mg / L, effluent COD below 30 mg / L, effluent TP below 0.3 mg / L, and an average TN removal load of not less than 0.1 kg·N / m³ / d;

[0010] S2, start the sludge circulation, sewage and granular sludge are mixed in the instantaneous mixing tube and then enter the first mixing zone;

[0011] The contact mixing time of sewage and short-range nitrification granular sludge in the instantaneous mixing tube is 5±1s, the hydraulic retention time in the first mixing zone and the second mixing zone is 25±1min respectively, and the sludge return ratio is 50-150%;

[0012] If the average particle size of the short-range nitrification granular sludge is lower than 120μm, adjust the contact mixing time of the sewage and granular sludge in the instantaneous mixing tube to 15-20s, the hydraulic retention time in the first mixing zone to 0-15min, the hydraulic retention time in the second mixing zone to 0-20min, and the sludge return ratio to 0-100%, until the average particle size of the short-range nitrification granular sludge recovers to above 120μm;

[0013] S3. Monitor the accumulated nitrite. When the short-range nitrification is destroyed, add alkali solution and hydrazine compound NOB inhibitor in the second mixing zone.

[0014] When the effluent TN of the deep denitrification and phosphorus removal device is greater than 12 mg / L, the ammonia nitrogen concentration is greater than 4 mg / L, and the nitrate nitrogen concentration is greater than 4 mg / L, add alkaline solution hydrazine combined with NOB inhibitor to make the effluent TN of the deep denitrification and phosphorus removal device less than 7 mg / L, the ammonia nitrogen concentration is less than 1.5 mg / L, and the nitrate nitrogen concentration is less than 1.5 mg / L;

[0015] S4. Monitor and control the DO concentration in the aerobic zone and the anaerobic ammonium oxidation zone to keep the nitrite concentration below 0.8 mg / L;

[0016] The DO concentration in the aerobic zone is 1.5~2.5mg / L. When the nitrite concentration in the aerobic zone is greater than 0.8mg / L, the DO concentration in the aerobic zone gradually decreases to 1.5mg / L.

[0017] The DO concentration in the anaerobic ammonium oxidation zone is 0.1~0.5mg / L. When the effluent ammonia nitrogen concentration is greater than 1.5mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone is increased to 0.3mg / L. When the effluent ammonia nitrogen concentration is lower than 1.5mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone is 0.1~0.2mg / L.

[0018] Optionally, the concentration of the alkaline solution hydrazine combined NOB inhibitor in the second mixing zone is 0.8~1.5mgN / L.

[0019] Optionally, the alkali hydrazine composite NOB inhibitor is prepared by mixing hydrazine sulfate and sodium bicarbonate in a ratio of 0.5:1 to 1:1.

[0020] Optionally, the sludge age of the deep denitrification and phosphorus removal device is 12-20 days.

[0021] Optionally, it also includes: the hydraulic retention time of the deep denitrification and phosphorus removal device is controlled within 4.5~8.5h.

[0022] Optionally, it also includes: the angle between the sewage in the instantaneous mixing pipe and the granular sludge pipe is 60°~90°.

[0023] The present invention provides a method for deep denitrification and phosphorus removal by coupling self-enrichment of granular sludge from continuous-flow municipal sewage with autotrophic biofilm, which has the following beneficial effects:

[0024] This method, without adding any external chemicals and without controlling the C / N ratio and temperature of the influent, self-enriches dense, regular, round granular sludge in a continuous-flow urban sewage deep denitrification and phosphorus removal device, and achieves short-term nitrification granular sludge of continuous-flow urban sewage through alkaline solution, ammonia and NOB inhibitor, and achieves deep denitrification and phosphorus removal by coupling short-term nitrification and denitrification of granular sludge with anaerobic ammonia oxidation, breaking through the technical bottlenecks of difficult cultivation of continuous-flow granular sludge, difficult realization of short-term nitrification granular sludge, and difficult realization of coupled denitrification of granular sludge and anaerobic ammonia oxidation.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0027] Figure 1A schematic structural diagram of a deep denitrification and phosphorus removal device for a method of deep denitrification and phosphorus removal using continuous-flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm according to an embodiment of the present invention is shown.

[0028] Figure 2 A schematic diagram of granular sludge in a method of continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal according to an embodiment of the present invention is shown.

[0029] Figure 3 A schematic diagram of a curve showing changes in effluent water quality of a method for continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal according to an embodiment of the present invention is shown.

[0030] Description of reference numerals:

[0031] 1. Urban sewage device; 2. Deep denitrification and phosphorus removal device; 3. Sedimentation device; 4. Alkaline hydrazine compound solution device;

[0032] 1.1. Sewage tank; 1.2. Overflow pipe; 1.3. Sewage pump;

[0033] 2.1. Sewage and sludge instantaneous mixing pipe; 2.2. First mixing zone; 2.3. Second mixing zone; 2.4. Aerobic zone; 2.5. Anaerobic ammonium oxidation zone; 2.6. Online instrument; 2.7. Air pump; 2.8. Variable speed mixer; 2.9. Aeration device; 2.10. First gas flowmeter; 2.11. First DO sensor; 2.12. Second gas flowmeter; 2.13. Third gas flowmeter; 2.14. Second DO sensor; 2.15. Third DO sensor; 2.16. Ammonia nitrogen and nitrate nitrogen sensor; 2.17. Anaerobic ammonium oxidation biofilm;

[0034] 3.1. Sedimentation tank; 3.2. Sludge return pump; 3.3. Residual sludge discharge pump; 3.4. Outlet pipe;

[0035] 4.1. Alkaline hydrazine compound solution tank; 4.2. Mixer; 4.3. Metering delivery pump. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0037] like Figure 1-3 As shown, a device for cultivating integrated short-range nitrification and anaerobic ammonium oxidation granular sludge comprises:

[0038] The first mixing zone, the second mixing zone, the aerobic zone, and the anaerobic ammonium oxidation zone are connected in sequence by overflow to form a deep denitrification and phosphorus removal device. The anaerobic ammonium oxidation zone is provided with an anaerobic ammonium oxidation biofilm. The overflow of the deep denitrification and phosphorus removal device is connected to a sedimentation tank. The sedimentation tank is connected to the first mixing zone through an instantaneous mixing pipe to form a sludge circulation.

[0039] S1. The deep denitrification and phosphorus removal device is inoculated with flocculent full-process nitrification sludge at a concentration of 2500~4500mg / L and then filled with sewage to make the flocculent full-process nitrification sludge self-aggregate into short-process nitrification granular sludge with an average particle size of 120-250μm and SVI=50~75;

[0040] The effluent from the deep denitrification and phosphorus removal device is stable for 15 consecutive days, with effluent ammonia nitrogen below 1.5 mg / L, effluent TN below 7 mg / L, effluent COD below 30 mg / L, effluent TP below 0.3 mg / L, and an average TN removal load of not less than 0.1 kg·N / m³ / d;

[0041] S2, start the sludge circulation, sewage and granular sludge are mixed in the instantaneous mixing tube and then enter the first mixing zone;

[0042] The contact mixing time of sewage and short-range nitrification granular sludge in the instantaneous mixing tube is 5±1s, the hydraulic retention time in the first mixing zone and the second mixing zone is 25±1min respectively, and the sludge return ratio is 50-150%;

[0043] If the average particle size of the short-range nitrification granular sludge is lower than 120μm, adjust the contact mixing time of the sewage and granular sludge in the instantaneous mixing tube to 15-20s, the hydraulic retention time in the first mixing zone to 0-15min, the hydraulic retention time in the second mixing zone to 0-20min, and the sludge return ratio to 0-100%, until the average particle size of the short-range nitrification granular sludge recovers to above 120μm;

[0044] S3. Monitor the accumulated nitrite. When the short-range nitrification is destroyed, add alkali solution and hydrazine compound NOB inhibitor in the second mixing zone.

[0045] When the effluent TN of the deep denitrification and phosphorus removal device is greater than 12 mg / L, the ammonia nitrogen concentration is greater than 4 mg / L, and the nitrate nitrogen concentration is greater than 4 mg / L, add alkaline solution hydrazine combined with NOB inhibitor to make the effluent TN of the deep denitrification and phosphorus removal device less than 7 mg / L, the ammonia nitrogen concentration is less than 1.5 mg / L, and the nitrate nitrogen concentration is less than 1.5 mg / L;

[0046] S4. Monitor and control the DO concentration in the aerobic zone and the anaerobic ammonium oxidation zone to keep the nitrite concentration below 0.8 mg / L;

[0047] The DO concentration in the aerobic zone is 1.5~2.5mg / L. When the nitrite concentration in the aerobic zone is greater than 0.8mg / L, the DO concentration in the aerobic zone gradually decreases to 1.5mg / L.

[0048] The DO concentration in the anaerobic ammonium oxidation zone is 0.1~0.5mg / L. When the effluent ammonia nitrogen concentration is greater than 1.5mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone is increased to 0.3mg / L. When the effluent ammonia nitrogen concentration is lower than 1.5mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone is 0.1~0.2mg / L.

[0049] Specifically, the method can be divided into a preparation phase and a processing phase, wherein:

[0050] Preparation stage: Based on the non-short-term nitrification granular sludge, short-term nitrification granular sludge is cultivated from the floc full-process nitrification sludge.

[0051] The deep denitrification and phosphorus removal device is inoculated with flocculent sludge and anaerobic ammonium oxidation biofilm. The sewage is removed from the deep denitrification and phosphorus removal device, and the mud-water mixture of COD, TP and TN enters the sedimentation device. The treated water after sedimentation is discharged, including:

[0052] Instantaneous mixing tube: creates favorable conditions for the instantaneous contact between sewage and sludge and the aggregation of bacterial colonies;

[0053] The first mixing zone: short-term mixing, uniform bacterial aggregation and anaerobic phosphorus release;

[0054] The second mixing zone: short-term mixing, uniform bacterial aggregation and anaerobic phosphorus release;

[0055] Aerobic zone: completes biological carbon and phosphorus removal and performs partial short-range nitrification;

[0056] Anaerobic ammonium oxidation zone: carries out granular sludge short-cut nitrification and denitrification and autotrophic anaerobic ammonium oxidation deep denitrification;

[0057] Sedimentation tank: for mud and water separation.

[0058] Treatment stage: The sludge circulation is started to circulate the short-range nitrification granular sludge.

[0059] The instantaneous mixing tube of sewage and sludge in the deep denitrification and phosphorus removal device realizes instantaneous contact between sewage and sludge, so that sewage and granular sludge are fully in contact. Sewage impurities and granular sludge debris are flocculated in the instantaneous mixing tube to increase the degree of granulation. At the same time, the intense mixing contact also causes a feast / starvation reaction.

[0060] The municipal sewage and granular sludge then enter the first and second mixing zones, where the sewage and sludge are briefly and evenly mixed, creating favorable conditions for bacterial aggregation and anaerobic phosphorus release. Granular sludge particle size is monitored during the process, and its status is used to determine the progress of the water treatment reaction and ensure stable operation of short-range nitrification.

[0061] If any problem occurs, add alkali solution and ammonia compound NOB inhibitor for regulation, and confirm the regulation effect based on the effluent water quality.

[0062] At the same time, the DO concentration can be controlled in the aerobic zone and the anaerobic ammonium oxidation zone to keep the nitrite accumulation below 0.8 mg / L, greatly reducing the emission of greenhouse gas N2O.

[0063] Furthermore, the floc sludge self-aggregates to achieve granulation, and the alkali solution and ammonia compound NOB inhibitor are strategically added in the second mixing zone to achieve stable short-term nitrification of the system, that is, short-term nitrification granular sludge is achieved. Not only does the granular sludge continuously provide a stable matrix for anaerobic ammonia-oxidizing bacteria to complete deep denitrification, but the granular sludge itself also completes denitrification, that is, the continuous flow granular sludge self-enrichment and autotrophic biofilm coupling deep denitrification and phosphorus removal are achieved, breaking through the difficulties of continuous flow granular sludge self-enrichment and the coupling denitrification of granular sludge and autotrophic anaerobic ammonia oxidation.

[0064] In this embodiment, the concentration of the alkaline hydrazine combined NOB inhibitor in the second mixing zone is 0.8-1.5 mgN / L.

[0065] Specifically, the addition of alkali-hydrazine combined with NOB inhibitors simultaneously shortens the sludge age. Normally, the sludge age is 12-20 days, but this is shortened to 12 days when the addition is applied, until the effluent TN is less than 7 mg / L, the ammonia nitrogen concentration is less than 1.5 mg / L, and the nitrate nitrogen concentration is less than 1.5 mg / L, indicating short-term nitrification recovery.

[0066] Furthermore, the concentration of the alkaline hydrazine complex solution is controlled at 0.8~1.5mgN / L, which greatly improves the selective inhibition of NOB without significantly affecting the activity of other bacterial communities, and can quickly achieve stable short-range nitrification.

[0067] In this embodiment, the alkali hydrazine combined NOB inhibitor is prepared by mixing hydrazine sulfate and sodium bicarbonate in a ratio of 0.5:1 to 1:1.

[0068] Specifically, the inhibitor is formulated with hydrazine sulfate and sodium bicarbonate in a ratio of 0.5:1 to 1:1. This inhibitor offers advantages such as easy preparation, low dosage, and high inhibition efficiency, enabling stable short-range nitrification. The inhibitory effect is superior to that of traditional hydrazine sulfate solutions, while the overall cost is lower.

[0069] In this embodiment, the sludge age of the deep denitrification and phosphorus removal device is 12-20 days.

[0070] Specifically, 4) the hydraulic retention time of the deep denitrification and phosphorus removal device is controlled at 4.5~8.5h, the temperature is 14~27℃, and normal temperature environment can be used.

[0071] In this embodiment, the hydraulic retention time of the deep denitrification and phosphorus removal device is controlled within a range of 4.5 to 8.5 hours.

[0072] In this embodiment, the angle between the sewage in the instantaneous mixing pipe and the granular sludge pipe is 60° to 90°.

[0073] Specifically, the mixing angle of sewage and granular sludge is controlled to accelerate the mixing of the two, avoid mutual countercurrent to break up sludge particles and slow down the flow rate. Example

[0074] The deep denitrification and dephosphorization device 2 is connected to the urban sewage device 1 and the sedimentation device 3 in front and back, and is provided with an alkaline hydrazine composite solution device 4 for adding an alkaline hydrazine composite NOB inhibitor.

[0075] The urban sewage device 1 includes a sewage tank 1.1, an overflow pipe 1.2, and a sewage delivery pump 1.3; the deep denitrification and phosphorus removal device 2 includes a sewage and sludge instantaneous mixing pipe 2.1, a first mixing zone 2.2, a second mixing zone 2.3, an aerobic zone 2.4, an anaerobic ammonium oxidation zone 2.5, an online instrument 2.6, and an air pump 2.7; the sewage delivery pump 1.3 is connected to the sewage and sludge instantaneous mixing pipe 2.1, the sewage and sludge instantaneous mixing pipe 2.1 is connected to the first mixing zone 2.2, the first mixing zone 2.2 is connected to the second mixing zone 2.3, and the second mixing zone 2.4 is connected to the second mixing zone 2.5. 3 is connected to the aerobic zone 2.4, the aerobic zone 2.4 is connected to the anaerobic ammonium oxidation zone 2.5, and the anaerobic ammonium oxidation zone 2.5 is connected to the sedimentation device 3; the first mixing zone 2.2 and the second mixing zone 2.3 are both equipped with a variable speed mixer 2.8; the aerobic zone 2.4 is equipped with an aeration device 2.9, a first gas flow meter 2.10, and a first DO sensor 2.11; the anaerobic ammonium oxidation zone 2.5 is equipped with an aeration device 2.9, a second gas flow meter 2.12, a third gas flow meter 2.13, a second DO sensor 2.14, and a third online DO sensor 2. 15, ammonia nitrogen and nitrate sensor 2.16, anaerobic ammonium oxidation biofilm 2.17; online instrument 2.6 is respectively connected to the first DO sensor 2.11, the second DO sensor 2.14, the third DO sensor 2.15, and the online ammonia nitrogen and nitrate sensor 2.16; the air pump 2.7 is respectively connected to the aeration device 2.9 through the first gas flow meter 2.10, the second gas flow meter 2.12, the third gas flow meter 2.13; the sedimentation device 3 includes a sedimentation tank 3.1, a sludge return pump 3.2, a residual sludge discharge pump 3.3, and an outlet pipe 3.4; the sedimentation tank 3.1 is connected to the first mixing zone 2.2 through a sludge return pump 3.2, the sedimentation tank 3.1 is connected to the sewage and sludge instantaneous mixing pipe 2.1 through a residual sludge discharge pump 3.3, and the effluent from the sedimentation tank 3.1 is discharged through the outlet pipe 3.4; the alkaline hydrazine composite solution device 4 includes an alkaline hydrazine composite solution tank 4.1, a mixer 4.2, and a metering delivery pump 4.3; the alkaline hydrazine composite solution tank 4.1 is connected to the second mixing zone 2.3 through a metering delivery pump 4.3; the alkaline hydrazine composite solution tank 4.1 is installed with a mixer 4.2.

[0076] The deep denitrification and phosphorus removal device 2 uses the sewage and sludge instantaneous mixing pipe 2.1 to achieve instantaneous contact between sewage and sludge, and enters the first mixing zone 2.2 and the second mixing zone 2.3 to achieve short-term and uniform mixing of sewage and sludge, thereby creating favorable conditions for bacterial aggregation and achieving anaerobic phosphorus release at the same time. The DO concentration is controlled in the aerobic zone 2.4 and the anaerobic ammonium oxidation zone 2.5 to achieve nitrite accumulation below 0.8 mg / L, greatly reducing the emission of greenhouse gas N2O. Through the controlled operation of the system, the floc sludge in the system self-aggregates to achieve granulation, with an average particle size of more than 120μm, and the particles are dense, regular circles with an SVI of 50~75. In addition, by strategically adding alkaline solution and ammonia compound NOB inhibitor in the second mixing zone 2.3, stable short-term nitrification of the system is achieved, that is, short-term nitrification granular sludge is achieved. Not only does the granular sludge continuously provide a stable matrix for anaerobic ammonia-oxidizing bacteria to complete denitrification, but the granular sludge itself also completes denitrification, that is, the continuous flow granular sludge self-enrichment and autotrophic biofilm coupling deep denitrification and phosphorus removal are achieved. The realization of this system has broken through the difficulties of continuous flow granular sludge and the coupling denitrification of granular sludge and autotrophic anaerobic ammonia oxidation.

[0077] The effluent from the primary sedimentation tank of a sewage treatment plant in Beijing is taken as urban sewage, and the water quality is shown in Table 1.

[0078]

[0079] Note: The above indicators are all in mg / L, and the water samples are not filtered;

[0080] 1) Inoculate the common flocculent full-process nitrification sludge in the first mixing zone 2.2, the second mixing zone 2.3, the aerobic zone 2.4, and the anaerobic ammonium oxidation zone 2.5 of the deep denitrification and phosphorus removal device 2, and maintain the common flocculent full-process nitrification sludge concentration in the first mixing zone 2.2, the second mixing zone 2.3, the aerobic zone 2.4, and the anaerobic ammonium oxidation zone 2.5 at 3000~3500mg / L; inoculate the anaerobic ammonium oxidation biofilm 2.17 of the anaerobic ammonium oxidation biofilm in the anaerobic ammonium oxidation zone 2.5 with a filling ratio of 25%; the urban sewage flows through the urban sewage device in sequence through the sewage and sludge instant mixing pipe 2.1, the first mixing zone 2.2, the second mixing zone 2.3, the aerobic zone 2.4, the anaerobic ammonium oxidation zone 2.5, and the sedimentation tank 3.1, and the sewage and sewage are respectively subjected to the treatment. The instantaneous contact of the sludge creates favorable conditions for bacterial aggregation, the short-term mixing leads to uniform bacterial aggregation and anaerobic phosphorus release, the short-term mixing leads to uniform bacterial aggregation and anaerobic phosphorus release, the biological carbon and phosphorus removal is completed and partial short-term nitrification is carried out, the granular sludge short-term nitrification and denitrification and autotrophic anaerobic ammonium oxidation deep nitrogen removal are carried out, and the sludge and water separation is carried out to deeply remove the total nitrogen, phosphorus and organic matter in the sewage; when the ordinary flocculent full-process nitrification sludge in the deep denitrification and phosphorus removal device 2 is converted into short-term nitrification granular sludge with an average particle size of 120μm~250μm, the SVI is 50~75, the effluent ammonia nitrogen is less than 1.5mg / L, the effluent TN is less than 7mg / L, the effluent COD is less than 30mg / L, the effluent TP is less than 0.3mg / L, and the average TN removal load is not less than 0.1kg·N / m³ / d, and it operates stably for more than 15 days, it is considered that the continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal process has been successfully started and has reached stable operation.

[0081] 2) The sludge in the sedimentation tank 3.1 is returned to the sewage-sludge instantaneous mixing pipe 2.1 through the sludge return pump 3.2 for instantaneous mixing with the municipal sewage. The instantaneous contact time is 5 seconds, the residence time in the first mixing zone 2.2 and the second mixing zone 2.3 are both 25 minutes, and the sludge return ratio is 50% to 150%. When the average particle size of the granular sludge in the deep denitrification and phosphorus removal device 2 is less than 120 μm, the instantaneous contact time between the municipal sewage and the returned sludge in the sewage-sludge instantaneous mixing pipe 2.1 is adjusted to no less than 15 seconds, the residence time in the first mixing zone 2.2 is shortened to no more than 15 minutes, and the residence time in the second mixing zone 2.3 is shortened to no more than 20 minutes. The sludge return ratio does not exceed 100%, until the average particle size of the granular sludge recovers to above 120 μm.

[0082] 3) The sludge age of deep denitrification and phosphorus removal device 2 is controlled between 12 and 20.0 days. When the effluent TN is greater than 12 mg / L, the ammonia nitrogen concentration is greater than 4 mg / L, the nitrate nitrogen concentration is greater than 4 mg / L, and the nitrite concentration is less than 1.5 mg / L, it indicates that the accumulated nitrite in the deep denitrification and phosphorus removal device is insufficient to supply anaerobic ammonium oxidation and granular sludge for denitrification, i.e., short-cut nitrification is destroyed. Immediately start the metering pump 4.3 of the alkaline hydrazine composite solution device 4 to add the alkaline hydrazine composite solution to the second mixing zone 2.3. The concentration of the alkaline hydrazine composite solution in the second mixing zone 2.3 is controlled to 1.0 mgN / L, and the sludge age is shortened to 12 days. This is continued until the effluent TN is less than 7 mg / L, the ammonia nitrogen concentration is less than 1.5 mg / L, and the nitrate nitrogen concentration is less than 1.5 mg / L, i.e., short-cut nitrification is restored. Then, shut down the metering pump 4.3 and stop adding the alkaline hydrazine composite solution.

[0083] 4) The hydraulic retention time of deep denitrification and phosphorus removal device 2 is controlled at 4.5~8.5h, the temperature is 14~27℃, the 2.4DO concentration in the aerobic zone is controlled at 1.5~2.5mg / L, when the 2.4 nitrite concentration in the aerobic zone is higher than 0.8mg / L, the 2.4DO concentration in the aerobic zone is gradually reduced to 1.5mg / L, and the 2.4 nitrite concentration in the aerobic zone is maintained below 0.8mg / L; the 2.5DO concentration in the anaerobic ammonium oxidation zone is 0.1~0.5mg / L, and the concentration is gradually reduced to 1.5mg / L. In the direction of water flow, the DO concentration shows a decreasing trend. When the effluent ammonia nitrogen concentration is higher than 1.5 mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone 2.5 is increased to 0.3 mg / L. When the effluent ammonia nitrogen concentration is lower than 1.5 mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone 2.5 is 0.1~0.2 mg / L. By controlling the DO concentration, the nitrite concentration in the deep denitrification and phosphorus removal device is maintained below 0.8 mg / L, thereby greatly reducing the emission of greenhouse gas N2O.

[0084] This method achieves high-quality effluent water quality through the self-enrichment of granular sludge in continuous-flow municipal sewage coupled with autotrophic biofilm deep denitrification and phosphorus removal. The effluent ammonia nitrogen is less than 1.5 mg / L, the effluent TN is less than 7 mg / L, the effluent COD is less than 30 mg / L, and the effluent TP is less than 0.3 mg / L. The average TN removal load is as high as 0.1-0.2 kg·N / m³ / d, which is about 2-4 times that of existing municipal sewage denitrification processes.

[0085] At the same time, it can greatly save treatment costs, save land, and greatly reduce greenhouse gas emissions. It is a new type of green, low-carbon and efficient sewage denitrification process. It is simple to operate and transform, and can be easily applied to new or renovated sewage treatment plants.

[0086] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for deep denitrification and phosphorus removal by continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm, characterized in that: include: The first mixing zone, the second mixing zone, the aerobic zone, and the anaerobic ammonium oxidation zone are connected in sequence by overflow to form a deep denitrification and phosphorus removal device. The anaerobic ammonium oxidation zone is provided with an anaerobic ammonium oxidation biofilm. The overflow of the deep denitrification and phosphorus removal device is connected to a sedimentation tank. The sedimentation tank is connected to the first mixing zone through an instantaneous mixing pipe to form a sludge circulation. S1. The deep denitrification and phosphorus removal device is inoculated with flocculent full-process nitrification sludge at a concentration of 2500~4500mg / L and then filled with sewage to make the flocculent full-process nitrification sludge self-aggregate into short-process nitrification granular sludge with an average particle size of 120-250μm and SVI=50~75; The effluent from the deep denitrification and phosphorus removal device is stable for 15 consecutive days, with effluent ammonia nitrogen below 1.5 mg / L, effluent TN below 7 mg / L, effluent COD below 30 mg / L, effluent TP below 0.3 mg / L, and an average TN removal load of not less than 0.1 kg·N / m³ / d; S2, start the sludge circulation, sewage and granular sludge are mixed in the instantaneous mixing tube and then enter the first mixing zone; The contact mixing time of sewage and short-range nitrification granular sludge in the instantaneous mixing tube is 5±1s, the hydraulic retention time in the first mixing zone and the second mixing zone is 25±1min respectively, and the sludge return ratio is 50-150%; If the average particle size of the short-range nitrification granular sludge is lower than 120μm, adjust the contact mixing time of the sewage and granular sludge in the instantaneous mixing tube to 15-20s, the hydraulic retention time in the first mixing zone to 0-15min, the hydraulic retention time in the second mixing zone to 0-20min, and the sludge return ratio to 0-100%, until the average particle size of the short-range nitrification granular sludge recovers to above 120μm; S3. Monitor the accumulated nitrite. When the short-range nitrification is destroyed, add alkali solution and hydrazine compound NOB inhibitor in the second mixing zone. When the effluent TN of the deep denitrification and phosphorus removal device is greater than 12 mg / L, the ammonia nitrogen concentration is greater than 4 mg / L, and the nitrate nitrogen concentration is greater than 4 mg / L, add alkaline solution hydrazine combined with NOB inhibitor to make the effluent TN of the deep denitrification and phosphorus removal device less than 7 mg / L, the ammonia nitrogen concentration is less than 1.5 mg / L, and the nitrate nitrogen concentration is less than 1.5 mg / L; S4. Monitor and control the DO concentration in the aerobic zone and the anaerobic ammonium oxidation zone to keep the nitrite concentration below 0.8 mg / L; The DO concentration in the aerobic zone is 1.5~2.5mg / L. When the nitrite concentration in the aerobic zone is greater than 0.8mg / L, the DO concentration in the aerobic zone gradually decreases to 1.5mg / L. The DO concentration in the anaerobic ammonium oxidation zone is 0.1~0.5mg / L. When the effluent ammonia nitrogen concentration is greater than 1.5mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone is increased to 0.3mg / L. When the effluent ammonia nitrogen concentration is lower than 1.5mg / L, the DO concentration at the end of the anaerobic ammonium oxidation zone is 0.1~0.2mg / L. Among them, in the deep denitrification and phosphorus removal device, sewage and sludge achieve instantaneous contact in the instantaneous mixing tube, so that sewage and granular sludge are fully in contact. Sewage impurities and granular sludge debris in the instantaneous mixing tube flocculate to improve the degree of granulation. At the same time, the intense mixing contact also causes a feast / starvation reaction; Afterwards, the municipal sewage mixed with granular sludge enters the first mixing zone and the second mixing zone in turn, so that the sewage and sludge are mixed evenly in a short time, thereby creating favorable conditions for bacterial aggregation and achieving anaerobic phosphorus release; The flocculent sludge self-aggregates to form granules. In the second mixing zone, alkali solution and hydrazine compound NOB inhibitor are strategically added to achieve stable short-range nitrification in the system, that is, short-range nitrification granular sludge is achieved. Not only does the granular sludge continuously provide a stable substrate for anaerobic ammonium oxidizing bacteria to achieve deep denitrification, but the granular sludge itself also completes denitrification. Adding alkali solution and hydrazine combined with NOB inhibitor can shorten the sludge age.

2. The method of continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal according to claim 1, characterized in that: The concentration of alkaline hydrazine combined NOB inhibitor in the second mixing zone is 0.8~1.5mgN / L.

3. The method of continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal according to claim 1, characterized in that: The alkaline hydrazine compound NOB inhibitor is prepared by mixing hydrazine sulfate and sodium bicarbonate in a ratio of 0.5:1 to 1:

1.

4. The method of continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal according to claim 1, characterized in that: The sludge age of the deep denitrification and phosphorus removal device is 12-20 days.

5. The method of continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal according to claim 1, characterized in that: Also includes: The hydraulic retention time of the deep denitrification and phosphorus removal device is controlled at 4.5~8.5h.

6. The method of continuous flow municipal sewage granular sludge self-enrichment coupled with autotrophic biofilm deep denitrification and phosphorus removal according to claim 1, characterized in that: Also includes: The angle between the sewage in the instantaneous mixing tube and the granular sludge tube is 60°~90°.

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