A method for realizing autotrophic nitrogen removal and biological phosphorus removal from municipal sewage by using A / O-MBBR with ultra-short hydraulic retention time without internal circulation

Abstract

The method of realizing autotrophic denitrification and biological phosphorus removal of urban sewage by A / O-MBBR without internal circulation and ultra-short hydraulic retention time belongs to the technical field of biological treatment of urban sewage. The steps of the present invention are as follows: (1) inoculating the residual sludge of the sewage treatment plant, the influent is urban sewage, and operating in anoxic / aerobic mode in a continuous flow reactor without internal circulation and with ultra-short HRT; realizing short-range nitrification by controlling the sludge age and the residual ammonia nitrogen in the effluent; (2) rapid self-enrichment Anammox and stable operation stage, adding blank filler with a volume filling ratio of 15%-25% to the ultra-short HRT reactor, the filler quickly realizes biofilm under high operating load conditions and realizes self-enrichment of anaerobic ammonia-oxidizing bacteria in the biofilm, and finally realizes stable, efficient and cost-effective autotrophic denitrification and biological phosphorus removal of urban sewage by controlling the dissolved oxygen in the aerobic zone.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological sewage treatment, and specifically relates to a method for realizing autotrophic nitrogen removal and biological phosphorus removal of urban sewage by using an A / O-MBBR without internal circulation and ultra-short hydraulic retention time. Background Art

[0002] At present, anaerobic ammonium oxidation (anammox) is recognized as the most environmentally friendly and resource-saving biological denitrification technology in the world, and it has great application potential in mainstream urban sewage. Anaerobic ammonium oxidizing bacteria are the main functional bacteria of this technology. Under anaerobic conditions, they use nitrite (NO2 - ) as an electron acceptor, which can convert ammonia nitrogen (NH4 + ) is directly oxidized to nitrogen (N2), which completely subverts the high-energy-consuming and low-efficiency nitrification-denitrification denitrification pathway of traditional sewage plants. However, mainstream urban sewage usually contains enough NH4 + , but NO2 - Recently, it has been proposed that short-range denitrification may be a feasible way to supply nitrite, providing a new idea for the realization of anaerobic ammonium oxidation of mainstream urban sewage and also for the treatment of nitrate (NO3 - -N) provides a new method for wastewater treatment.

[0003] Studies have shown that Anammox bacteria are widely present in urban sewage treatment plants, but their relative abundance is extremely low. One possible reason is that the sludge retention time of sewage treatment plants is usually not enough to retain low-growth anaerobic ammonium-oxidizing bacteria. Adding fillers can decouple sludge discharge from the sludge age of the system, so that the anaerobic ammonium-oxidizing bacteria enriched on the fillers can theoretically have an infinite sludge age. In addition, existing studies have shown that the anaerobic zone in the sewage treatment process is a hot zone for anaerobic ammonium-oxidizing enrichment. The sufficient electron donors in the anaerobic zone make it possible to provide nitrite substrates for anaerobic ammonium-oxidizing bacteria through short-range denitrification pathways. Therefore, adding fillers to the anaerobic zone of the reactor makes it easier to enrich anaerobic ammonium-oxidizing bacteria.

[0004] The substrate load is positively correlated with the growth rate of microorganisms. Increasing the nitrogen substrate load within a certain range will further increase the proliferation rate of anaerobic ammonium oxidizing bacteria, which is one of the main reasons why anaerobic ammonium oxidizing bacteria are more likely to be enriched in high-ammonia nitrogen wastewater. Methods to increase the load in the sewage treatment process include increasing the influent substrate concentration, shortening the hydraulic retention time and reducing the sludge age. Compared with increasing the substrate concentration, the adjustment of the hydraulic retention time and sludge age is more feasible in actual engineering. However, how to balance the vicious competition between heterotrophic denitrification and autotrophic anaerobic ammonium oxidation in substrates and ecological niches under high load conditions is one of the key factors in achieving rapid enrichment of anaerobic ammonium oxidizing bacteria. If anaerobic ammonium oxidizing bacteria can be rapidly enriched in the mainstream high-load urban sewage treatment process, it will provide a more meaningful method for the large-scale application of anammox technology in practice. Summary of the invention

[0005] The present invention proposes a method for realizing autotrophic nitrogen removal and biological phosphorus removal of urban sewage by using an A / O-MBBR without internal circulation and ultra-short hydraulic retention time, with the aim of solving the problem that anaerobic ammonia-oxidizing bacteria in urban sewage are difficult to quickly enrich and retain for a long time in mainstream low-ammonia nitrogen urban sewage.

[0006] To achieve the above objectives, the technical solution adopted in the present invention is to first achieve nitrite accumulation by controlling the sludge age and the dissolved oxygen in the aerobic zone in a continuous flow system in anoxic / aerobic operation mode with ultra-short hydraulic retention time, and then add suspended fillers into the reactor to form a high-load A / O moving bed biofilm reactor, which quickly self-enriches anaerobic ammonia-oxidizing bacteria, and finally achieves synchronous autotrophic nitrogen removal and biological phosphorus removal.

[0007] A method for realizing autotrophic denitrification and biological phosphorus removal of urban sewage by using an ultra-short hydraulic retention time A / O-MBBR without internal circulation is characterized in that: the required devices include an urban sewage raw water tank (1), an ultra-short hydraulic retention time A / O-MBBR reactor (2), and a secondary sedimentation tank (3); the ultra-short hydraulic retention time A / O-MBBR reactor is divided into four areas along the water inlet direction by a perforated partition plate, which are an anaerobic area (2.1) for adding suspended fillers and three aerobic areas (2.2), (2.3), and (2.4) for adding suspended fillers; the added fillers are all blank fillers (2.6); the urban sewage raw water tank (1) pumps sewage into the ultra-short hydraulic retention time A / O-MBBR reactor through an inlet pump (1.1) The anaerobic zone (2.1) in the residence time A / O-MBBR reactor (2); wherein a stirrer (2.5) is provided in the anaerobic zone; an aeration pump (2.10) is connected to an aeration plate (2.8) through a rotor flowmeter (2.9) to continuously provide oxygen to the aerobic zone; a detection device DO probe (2.7) is connected to an online water quality detector (2.12); the online water quality detector (2.12) is connected to a computer (2.13); the bottom of the secondary sedimentation tank (3) is connected to the anaerobic zone (2.1) through a return sludge control valve (3.2) and a sludge return pump (2.11), and the remaining sludge is discharged through a control valve (3.3); wherein a sludge scraper (3.1) is provided in the secondary sedimentation tank to prevent the sludge from floating;

[0008] Phase 1, vaccination and activation, includes the following steps:

[0009] The residual sludge from the municipal sewage treatment plant was inoculated into the non-circulating ultra-short hydraulic retention time A / O-MBBR continuous flow reactor, and the inoculated sludge concentration was 3500-5200 mg / L; the influent was actual municipal sewage, and the sludge return volume ratio and sludge age were designed to be 120-150% and 6-8d respectively; the hydraulic retention time of the anaerobic zone was designed to be 40-60min, that of the aerobic zone to be 90-140min, the total hydraulic retention time of the reactor to be 120-200min, and the volumetric nitrogen load of the reactor to be maintained at 0.35-0.75Kg Nm -3 d -1 , the dissolved oxygen concentration in the aerobic zone is controlled at 0.12-2.4 mg / L by a rotor flow meter;

[0010] When the effluent ammonia nitrogen in the aerobic zone is greater than 10 mg / L, the hydraulic retention time in the aerobic zone is extended to 120-140 min and the dissolved oxygen concentration is increased to 1-2.5 mg / L; when the effluent ammonia nitrogen concentration in the aerobic zone is less than 1 mg / L, the hydraulic retention time in the aerobic zone is shortened to 90-120 min and the dissolved oxygen is reduced to 0.12-1.5 mg / L; when the effluent ammonia nitrogen is 5-10 mg / L, the ammonia nitrogen removal efficiency is greater than 85%, the nitrite accumulation concentration in the aerobic zone is greater than 3 mg / L, and the nitrite accumulation rate is greater than 25% and is maintained stably for more than 20 days, it indicates that the high-load A / O continuous flow reactor is successfully started;

[0011] Phase II, rapid self-enrichment of Anammox and stable operation phase, the specific steps include:

[0012] An A / O-MBBR reactor is constructed by adding blank fillers to an ultra-short hydraulic retention time A / O reactor, and the filler volume filling ratio is 15-25%; when the ammonia nitrogen in the effluent of the aerobic zone is less than 1 mg / L, the phosphorus is less than 0.5 mg / L, and the nitrate nitrogen is greater than 15 mg / L, the sludge return volume ratio is increased to 1.4-1.5 and the dissolved oxygen in the aerobic zone is reduced to 0.12-1.5 mg / L; when the ammonia nitrogen in the effluent of the aerobic zone is greater than 5 mg / L, and the phosphorus is greater than 0.5 mg / L, the dissolved oxygen concentration in the aerobic zone is increased to 0.5-2 mg / L and the sludge age is reduced to 6-7 days. When the effluent phosphorus concentration is less than 0.5 mg / L, the total inorganic nitrogen removal contribution rate of the aerobic zone is greater than 40%, and the actual total inorganic nitrogen removal rate of the reactor minus the theoretical removal rate is greater than 20% and can be maintained stably for more than 30 days, it means that the anaerobic ammonia-oxidizing bacteria have achieved rapid self-enrichment on the biofilm of the filler, autotrophic nitrogen removal has been enhanced, and the system has achieved simultaneous nitrogen and phosphorus removal of low C / N urban sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0014] Figure 1 Among them, 1-urban sewage raw water tank; 2-ultra-short hydraulic retention time A / O-MBBR reactor; 3-secondary sedimentation tank; 1.1-water inlet pump; 2.1-anaerobic zone; 2.2, 2.3, 2.4-aerobic zone; 2.5-anaerobic agitator; 2.6-suspended blank filler; 2.7-DO probe; 2.8-aeration disc; 2.9-rotor flowmeter; 2.10-aeration pump; 2.11-sludge return pump; 2.12-online water quality detector; 2.13-computer; 3.1-secondary sedimentation tank sludge scraper; 3.2-return sludge control valve; 3.3-sludge discharge control valve. DETAILED DESCRIPTION

[0015] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Figure 1) is an ultra-short hydraulic retention time continuous flow reactor, the system device is provided with a city sewage raw water tank (1), an ultra-short hydraulic retention time A / O-MBBR reactor (2), and a secondary sedimentation tank (3); the ultra-short hydraulic retention time A / O-MBBR reactor is divided into four areas by a perforated partition plate, which are an anaerobic area (2.1) for adding suspended fillers and three aerobic areas (2.2), (2.3), and (2.4) for adding suspended fillers in the water inlet direction; wherein the added fillers are all blank fillers (2.6); the city sewage raw water tank (1) pumps sewage into the ultra-short hydraulic retention time A / O-MBBR reactor through a water inlet pump (1.1) The anaerobic zone (2.1) in the device (2); wherein a stirrer (2.5) is provided in the anaerobic zone; an aeration pump (2.10) is connected to an aeration plate (2.8) through a rotor flowmeter (2.9) to continuously provide oxygen to the aerobic zone; a detection device DO probe (2.7) is connected to an online water quality detector (2.12); the online water quality detector (2.12) is connected to a computer (2.13); the bottom of the secondary sedimentation tank (3) is connected to the anaerobic zone (2.1) through a return sludge control valve (3.2) and a sludge return pump (2.11), and the remaining sludge is discharged through a control valve (3.3); wherein a sludge scraper (3.1) is provided in the secondary sedimentation tank to prevent the sludge from floating up;

[0016] In the specific embodiment, the influent is the actual domestic sewage of a residential area in Beijing, and its specific water quality indicators are as follows: ammonia nitrogen concentration (NH4 + -N) is 35-78mg / L, nitrite concentration (NO2 - -N) is less than 1mg / L, nitrate concentration (NO3 - -N) is less than 1mg / L, COD concentration is 100-320mg / L, pH value is 7.0-7.3, COD / TIN is 2-4. The inoculated sludge comes from the residual sludge of a sewage treatment plant in Beijing, and the effective volume of the reactor is 24L.

[0017] The specific operation is as follows:

[0018] 1) Inoculation and startup phase: The reactor was inoculated with wastewater plant excess sludge at a concentration of 3268 mg / L and operated in anoxic / aerobic mode in an ultra-short hydraulic retention time continuous flow reactor, where the anoxic / aerobic hydraulic retention time was 45 min and 135 min respectively, and the total hydraulic retention time was 3 h. The average nitrogen load and organic load of the reactor were 0.51 kg Nm - 3 d -1 With 1.49Kg COD m -3 d -1The sludge return volume ratio is 120%, the sludge age is 6-8 days, and the dissolved oxygen concentration in the aerobic zone is controlled by a rotor flowmeter to be 0.1-2 mg / L. At this stage, the residual ammonia nitrogen concentration in the effluent of the aerobic zone is 5-10 mg / L. After 25 days of operation, obvious nitrite accumulation occurs in the aerobic zone, the nitrite concentration is greater than 3 mg / L, and the nitrite accumulation rate is 25-70%.

[0019] 2) Rapid self-enrichment of Anammox and stable operation stage: In this stage, blank fillers were added to various areas of the reactor with a volume filling ratio of 10%. After 30 days of operation, obvious biofilms were observed on the fillers, and the ammonia nitrogen removal in the anaerobic zone could reach 1.5-5 mg / L, the total inorganic nitrogen removal contribution rate in the aerobic zone was greater than 50%, and the nitrogen removal load of the reactor reached 0.47 kg N m -3 d -1 , the total inorganic nitrogen removal efficiency is greater than 80%, the total inorganic nitrogen concentration in the effluent is less than 15mg / L, and the effluent phosphorus concentration is less than 0.5mg / L.

[0020] The test results show that in a continuous flow reactor treating actual urban sewage, rapid self-enrichment of anaerobic ammonia-oxidizing bacteria can be achieved within 30 days. By strengthening the autotrophic denitrification of mainstream urban sewage, the system's total inorganic nitrogen removal efficiency and nitrogen removal load are significantly improved, and the system achieves simultaneous deep denitrification and phosphorus removal.

Claims

1. The method of realizing autotrophic nitrogen removal and biological phosphorus removal of urban sewage by using A / O-MBBR with ultra-short hydraulic retention time without internal circulation is characterized by: The device used comprises a city sewage raw water tank (1), an A / O-MBBR continuous flow reactor without internal circulation and ultra-short hydraulic retention time (2), and a secondary sedimentation tank (3); the A / O-MBBR continuous flow reactor without internal circulation and ultra-short hydraulic retention time is divided into four areas by an open-hole partition plate, which are an anaerobic area (2.1) for adding suspended fillers and an aerobic area with three grids for adding suspended fillers along the water inlet direction; the added fillers are all blank fillers (2.6); the city sewage raw water tank (1) pumps sewage into the A / O-MBBR continuous flow reactor without internal circulation and ultra-short hydraulic retention time through an inlet pump (1.1). The anaerobic zone (2.1) in the continuous flow reactor (2) is provided with a stirrer (2.5); the aeration pump (2.10) is connected to the aeration plate (2.8) through a rotor flowmeter (2.9) to continuously provide oxygen to the aerobic zone; the detection device DO probe (2.7) is connected to the water quality online detector (2.12); the water quality online detector (2.12) is connected to the computer (2.13); the bottom of the secondary sedimentation tank (3) is connected to the anaerobic zone (2.1) through a return sludge control valve (3.2) and a sludge return pump (2.11), and the remaining sludge is discharged through a control valve (3.3); The secondary sedimentation tank is equipped with a sludge scraper (3.1) to prevent sludge from floating up; Phase 1, vaccination and activation, includes the following steps: The residual sludge from the municipal sewage treatment plant was inoculated into the A / O-MBBR continuous flow reactor without internal circulation and ultra-short hydraulic retention time. The inoculated sludge concentration was 3500-5200 mg / L. The influent was actual municipal sewage, the sludge return volume ratio was 120%-150%, and the sludge age was 6-8 days. The hydraulic retention time of the anaerobic zone was designed to be 40-60 min, that of the aerobic zone to be 90-140 min, and the total hydraulic retention time of the reactor to be 120-200 min. The volumetric nitrogen load of the reactor was maintained at 0.35-0.75 kg N·m -3 ·d -1 , the dissolved oxygen concentration in the aerobic zone is controlled at 0.12-2.4 mg / L by a rotor flow meter; When the effluent ammonia nitrogen in the aerobic zone is greater than 10 mg / L, the hydraulic retention time in the aerobic zone is extended to 120-140 min and the dissolved oxygen concentration is increased to 1-2.5 mg / L; when the effluent ammonia nitrogen concentration in the aerobic zone is less than 1 mg / L, the hydraulic retention time in the aerobic zone is shortened to 90-120 min and the dissolved oxygen is reduced to 0.12-1.5 mg / L; when the effluent ammonia nitrogen is 5-10 mg / L, the ammonia nitrogen removal efficiency is greater than 85%, the nitrite accumulation concentration in the aerobic zone is greater than 3 mg / L, and the nitrite accumulation rate is greater than 25% and is maintained stably for more than 20 days, it indicates that the ultra-short hydraulic retention time A / O continuous flow reactor is successfully started; Phase II, rapid self-enrichment of Anammox and stable operation, includes the following steps: An A / O-MBBR reactor was constructed by adding blank fillers to an ultra-short hydraulic retention time A / O reactor, with a filler volume filling ratio of 15-25%; when the ammonia nitrogen in the effluent of the aerobic zone was less than 1 mg / L and the phosphorus was less than 0.5 mg / L, and the nitrate nitrogen was greater than 15 mg / L, the sludge return volume ratio was increased to 1.4-1.5 and the dissolved oxygen in the aerobic zone was reduced to 0.12-1.5 mg / L; when the ammonia nitrogen in the effluent of the aerobic zone was greater than 5 mg / L and the phosphorus was greater than 0.5 mg / L, the dissolved oxygen concentration in the aerobic zone was increased to 0.5-2 mg / L and the sludge age was reduced to 6-7 days.

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