A method, apparatus and application for nitrogen and phosphorus removal from anaerobic ammonia oxidation granular sludge

Abstract

This invention discloses a method, apparatus and application for nitrogen and phosphorus removal from anaerobic ammonia oxidation granular sludge. The method includes: (1) raw biogas slurry is fed into three separate locations to a primary pre-anoxic tank, an anaerobic tank and an integrated anaerobic ammonia oxidation reactor; the primary pre-anoxic tank is also fed with recycled sludge; (2) effluent from the anaerobic tank is fed into a primary sedimentation tank, the supernatant from the primary sedimentation tank is fed into the integrated anaerobic ammonia oxidation reactor, and the bottom sludge is fed into a secondary anoxic tank by a sludge pump; (3) calcium salt is added to the integrated anaerobic ammonia oxidation reactor to form hydroxyapatite crystal nuclei to accelerate the formation of anaerobic ammonia oxidation granular sludge, and alkali solution is added to control the pH value in the reactor to 7.5-8.3; (4) effluent from the integrated anaerobic ammonia oxidation reactor is fed into a secondary anoxic tank, the bottom of the secondary anoxic tank is connected to the aerobic tank; effluent from the aerobic tank is fed into a secondary sedimentation tank, the supernatant from the secondary sedimentation tank is discharged after meeting the standards, and the bottom sludge is recycled back to the primary pre-anoxic tank.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control technology, and specifically relates to an anaerobic ammonia oxidation granular sludge denitrification and phosphorus removal method, apparatus and application. Background Technology

[0002] Livestock and poultry farming wastewater is one of the major sources of pollution in my country. Its composition is complex, containing high concentrations of organic pollutants, suspended solids (SS), nitrogen and phosphorus pollutants, and pathogenic microorganisms. With the continuous advancement of my country's environmental protection policies, the requirements for the resource utilization and harmless treatment of livestock and poultry waste are constantly increasing. Anaerobic fermentation can effectively remove high concentrations of organic pollutants from livestock and poultry wastewater and convert them into methane for resource recovery, thus it is widely used in the treatment of livestock and poultry wastewater. However, due to the limitations of the anaerobic fermentation process, the anaerobic fermentation slurry still contains high concentrations of suspended solids, nitrogen and phosphorus, and residual biodegradable / inert organic matter. To meet relevant wastewater discharge standards, the anaerobic fermentation slurry must undergo further post-treatment before it can be discharged in compliance with regulations.

[0003] Anaerobic digestate from livestock farming has a high phosphorus content and a low C / N ratio. Traditional biological nitrogen and phosphorus removal technologies have several drawbacks, such as cumbersome operation and management, poor stability, long wastewater retention time, large land area requirements, high energy consumption, high investment, large chemical consumption, excessive nitrogen and phosphorus levels in effluent, and difficulty in phosphorus resource recovery. Therefore, environmental protection professionals have begun to focus on applying more energy-efficient and effective new biological nitrogen and phosphorus removal technologies to anaerobic digestate treatment to promote the sustainable development of my country's livestock industry. The novel biological nitrogen removal technology, nitrification-anaerobic ammonia oxidation, offers numerous advantages over traditional biological nitrogen removal technologies, including higher efficiency, lower energy consumption, lower treatment costs, and smaller land area. However, due to the low proliferation rate and low stability of anaerobic ammonia oxidizing bacteria, the key to improving the performance of its bioreactor is to quickly achieve microbial immobilization. The most effective method is to granulate the anaerobic ammonia oxidation sludge and increase the abundance of anaerobic ammonia oxidizing bacteria and system stability through granular anaerobic ammonia oxidation sludge. Phosphate rock, as a non-renewable resource, could significantly alleviate future phosphorus scarcity if phosphorus resources could be recovered and utilized from phosphorus-rich wastewater. Therefore, for wastewater such as anaerobic fermentation slurry from livestock wastewater, which is high in ammonia nitrogen, low C / N ratio, and high in phosphorus, a pressing issue is how to add low-cost calcium-based compounds to traditional nitrogen and phosphorus removal processes to simultaneously achieve phosphorus fixation and recovery while promoting the formation of anaerobic ammonia oxidation granular sludge. Summary of the Invention

[0004] The present invention aims to solve the technical problems existing in the prior art. To this end, the present invention provides a method for cultivating anaerobic ammonia oxidation granular sludge and its application, which makes full use of the synergistic effect of anaerobic ammonia oxidizing bacteria, nitrifying and denitrifying bacteria, and polyphosphate-accumulating bacteria to achieve the goals of high volumetric loading, excellent nitrogen and phosphorus removal effect, and low treatment cost, and has strong potential for engineering application and promotion.

[0005] According to a first aspect of the present invention, a method for nitrogen and phosphorus removal from anaerobic ammonia oxidation granular sludge is proposed, the process flow of which is as follows:

[0006] (1) The raw biogas slurry is fed into three separate locations: the primary pre-anoxic tank, the anaerobic tank, and the integrated anaerobic ammonia oxidation reactor; the primary pre-anoxic tank is also fed with recycled sludge.

[0007] (2) The effluent from the anaerobic tank is sent to the primary sedimentation tank, the clear liquid from the upper layer of the primary sedimentation tank is sent to the integrated anaerobic ammonia oxidation reactor, and the bottom sludge is pumped into the secondary anoxic tank.

[0008] (3) Calcium salt is added to the integrated anaerobic ammonia oxidation reactor to form hydroxyapatite crystal nuclei and accelerate the formation of anaerobic ammonia oxidation granular sludge. Alkali solution is added to control the pH value in the reactor to 7.5-8.3.

[0009] (4) The effluent from the integrated anaerobic ammonia oxidation reactor is sent to the secondary anoxic tank, and the bottom of the secondary anoxic tank is connected to the aerobic tank; the effluent from the aerobic tank is sent to the secondary sedimentation tank, the upper clear liquid of the secondary sedimentation tank is discharged after meeting the standards, and the bottom sludge is returned to the primary pre-anoxic tank.

[0010] The process involves stirring in the primary pre-anoxic tank, the anaerobic tank, and the secondary anoxic tank, and aeration in the integrated anaerobic ammonia oxidation reactor and the aerobic tank.

[0011] In some embodiments of the present invention, the process parameters of the raw biogas slurry are: ammonia nitrogen concentration of 500-2000 mg / L; and / or COD of 1000-4000 mg / L; and / or BOD of 500-3000 mg / L; and / or TP of 3-25 mg / L.

[0012] In some embodiments of the present invention, in step (1), the proportions of raw biogas slurry fed into the primary pre-anoxic tank, anaerobic tank and integrated anaerobic ammonia oxidation reactor are 5-30%, 30-55% and 40-65%, respectively.

[0013] In some embodiments of the present invention, the primary pre-anoxic tank is started by inoculating denitrifying sludge.

[0014] In some embodiments of the present invention, in step (1), the returned sludge is returned sludge from the secondary sedimentation tank.

[0015] Some of the biogas slurry and returned sludge are mixed in the primary pre-anoxic tank. The primary pre-anoxic tank is started by inoculating denitrifying sludge, which causes a denitrification reaction to remove nitrate nitrogen from the returned sludge, thus preventing the nitrate nitrogen in the returned sludge from affecting the phosphorus release effect of polyphosphate-accumulating bacteria in the subsequent anaerobic tank.

[0016] In some embodiments of the present invention, stirring is performed in a primary pre-anoxic tank, and the stirring frequency is controlled so that the dissolved oxygen does not exceed 0.6 mg / L.

[0017] In some embodiments of the present invention, the hydraulic retention time of the primary pre-anoxic tank is 2.8-16.8 h.

[0018] The effluent from the primary pre-anoxic tank enters the anaerobic tank, where some biogas slurry is mixed in. Stirring is then initiated to begin the phosphorus release reaction. The mixed biogas slurry replenishes the BOD5 required for the phosphorus release reaction. Polyphosphate-accumulating bacteria utilize the organic matter in the biogas slurry to synthesize poly-β-hydroxybutyrate (PHB), an intracellular carbon source storage product, thereby completing phosphate release and consuming the organic matter in the influent biogas slurry. When the effluent TP gradually increases and the BOD gradually decreases to below 50 mg / L, the anaerobic tank is considered to have successfully started up.

[0019] In some embodiments of the present invention, the anaerobic tank is started by inoculating denitrifying sludge.

[0020] In some embodiments of the present invention, the anaerobic tank is stirred, and the stirring frequency is controlled so that the dissolved oxygen does not exceed 0.2 mg / L.

[0021] In some embodiments of the present invention, the hydraulic retention time of the anaerobic tank is 1.0-3.5 h.

[0022] After treatment in the anaerobic tank, the effluent enters a primary sedimentation tank for sludge-water separation, preventing suspended sludge from subsequently entering the integrated anaerobic ammonia oxidation reactor and affecting the anaerobic ammonia oxidation activity. At the bottom of the primary sedimentation tank, a sludge pump discharges a portion of the sludge to the secondary anoxic tank at the rear to ensure effective aerobic phosphorus uptake; the remaining sludge is periodically discharged to control the sludge age of the entire system.

[0023] The effluent from the primary sedimentation tank is mixed with a portion of the biogas slurry and enters an integrated anaerobic ammonium oxidation (ANAO) reactor. Calcium salts are added, and in the reactor, they react with phosphates to produce hydroxyapatite, removing approximately half of the total phosphorus. Hydroxyapatite acts as a nucleus for ANAO granular sludge, allowing new ANAO cells to attach and grow, forming larger aggregates. Simultaneously, ANAO microorganisms secrete endogenous organic matter, such as extracellular polymeric substances (EPS), which have adhesive properties, promoting the bonding between organisms and between organisms and minerals, gradually forming larger, mature ANAO granular sludge.

[0024] In some embodiments of the present invention, in step (3), the calcium salt is calcium chloride, and the alkaline solution is at least one of sodium bicarbonate solution or sodium carbonate solution.

[0025] In some embodiments of the present invention, in step (3), calcium salt is added to the integrated anaerobic ammonia oxidation reactor, and the mass ratio of calcium to total phosphorus in the influent of the integrated anaerobic ammonia oxidation reactor is controlled to be (3-5):1.

[0026] In some embodiments of the present invention, the integrated anaerobic ammonia oxidation reactor is started by inoculating mature anaerobic ammonia oxidation sludge.

[0027] In some embodiments of the present invention, in step (3), an alkaline solution is added to adjust the pH to 7.5-8.3. The purpose of adding the alkaline solution is to maintain sufficient alkalinity in the reaction tank to replenish the alkali and inorganic carbon consumed by the integrated nitrification-anaerobic ammonia oxidation coupled reaction.

[0028] In some embodiments of the present invention, after the addition of calcium salt, a reflux pump is used to adjust the upward flow velocity in the integrated anaerobic ammonia oxidation reactor to 1.5-6 m / h. Controlling the reflux flow rate of the reflux pump in the reactor is beneficial to the formation of granular sludge.

[0029] In some embodiments of the present invention, the hydraulic retention time of the integrated anaerobic ammonia oxidation reactor is 2-7 hours.

[0030] Ammonia nitrogen in the wastewater comes into contact with the surface of the anaerobic ammonium oxidation granular sludge. By controlling the aeration rate, it is first oxidized to nitrite nitrogen by ammonia-oxidizing bacteria (AOB). Subsequently, in the anaerobic environment inside the granular sludge, anaerobic ammonium-oxidizing bacteria (AnAOB) use ammonia nitrogen and nitrite nitrogen as electron donors and acceptors, respectively, to react and generate N2, thereby removing most of the ammonia nitrogen and total nitrogen pollutants from the influent. Since the influent contains a certain amount of organic matter, approximately 60% of the organic matter can be removed by passing it through the anoxic and anaerobic tanks, resulting in a COD / ammonia nitrogen concentration ratio of <0.3 for the influent entering the integrated anaerobic ammonium oxidation reactor. Under these conditions, denitrification coupled with nitrogen removal occurs within the integrated anaerobic ammonium oxidation reactor, where the nitrate nitrogen generated by the anaerobic ammonium oxidation reaction is removed by denitrification. After treatment in the integrated anaerobic ammonium oxidation reactor, the effluent ammonia nitrogen is approximately 50 mg / L, and the effluent total nitrogen is approximately 60 mg / L, before entering the subsequent A / O stage for further nitrogen removal.

[0031] The effluent from the integrated anaerobic ammonia oxidation reactor enters the secondary anoxic tank-aerobic tank, with the internal recirculation ratio controlled between 200% and 400%. Denitrification sludge is inoculated to start the secondary anoxic tank. The secondary anoxic tank is equipped with a stirring device to control the dissolved oxygen concentration. An appropriate amount of carbon source is added through a carbon source dosing pump to remove nitrate nitrogen recirculated from the nitrification liquid in the aerobic tank. The dissolved oxygen concentration in the aerobic tank is regulated by controlling aeration. Under the action of polyphosphate-accumulating bacteria, phosphate in the liquid phase is absorbed and discharged. The nitrification liquid enters the secondary sedimentation tank and is discharged after meeting the standards. The sludge from the secondary sedimentation tank is returned to the primary pre-anoxic tank through a sludge return pump.

[0032] In some embodiments of the present invention, aeration is turned on in the integrated anaerobic ammonia oxidation reactor to control the dissolved oxygen in the effluent to 0.5-5 mg / L.

[0033] In some embodiments of the present invention, the secondary anoxic tank is started by inoculating denitrifying sludge.

[0034] In some embodiments of the present invention, the secondary anoxic tank is stirred, and the stirring frequency is controlled so that the dissolved oxygen does not exceed 0.6 mg / L.

[0035] In some embodiments of the present invention, step (4) further includes adding a carbon source to the secondary anoxic tank, wherein the carbon source is an organic carbon source.

[0036] In some preferred embodiments of the present invention, the carbon source is sodium acetate.

[0037] In some embodiments of the present invention, the hydraulic retention time of the secondary anoxic tank is 0.5-3 hours.

[0038] In some embodiments of the present invention, the aerobic tank is started by inoculating denitrifying sludge.

[0039] In some embodiments of the present invention, aeration is performed in the aerobic tank, and the aeration rate is adjusted to control the dissolved oxygen at 2-4 mg / L.

[0040] In some embodiments of the present invention, the hydraulic retention time of the aerobic tank is 4-6 hours.

[0041] In some embodiments of the present invention, in step (4), the reflux ratio of the bottom sludge is 200%-400%.

[0042] According to a second aspect of the present invention, a nitrogen and phosphorus removal device is provided for performing the anaerobic ammonia oxidation granular sludge nitrogen and phosphorus removal method as described in the first aspect of the present invention, comprising:

[0043] A primary pre-anoxic tank and an anaerobic tank, wherein the bottom of the primary pre-anoxic tank is connected to the anaerobic tank;

[0044] The system includes a primary sedimentation tank and an integrated anaerobic ammonia oxidation reactor. The effluent from the top of the anaerobic reactor flows by gravity to the primary sedimentation tank. The primary sedimentation tank is equipped with an effluent pipe at its upper part, which is connected to the bottom of the integrated anaerobic ammonia oxidation reactor. The effluent from the top of the primary sedimentation tank flows by gravity to the integrated anaerobic ammonia oxidation reactor.

[0045] The integrated anaerobic ammonia oxidation reactor has a secondary anoxic tank and an aerobic tank. The effluent from the top of the reactor flows by gravity to the secondary anoxic tank. The bottom of the secondary anoxic tank is connected to the aerobic tank.

[0046] The effluent from the top of the aerobic tank flows by gravity to the secondary sedimentation tank.

[0047] In some embodiments of the present invention, the first-stage pre-anoxic tank is provided with a first stirring device; the anaerobic tank is provided with a second stirring device; the second-stage anoxic tank is provided with a third stirring device; the integrated anaerobic ammonia oxidation reactor is provided with a first aeration disc; the aerobic tank is provided with a second aeration disc; and aeration of the first aeration disc and the second aeration disc is achieved by an aeration blower.

[0048] In some embodiments of the present invention, it further includes:

[0049] The system includes a raw water tank and a first water pump. The raw water tank contains biogas slurry, and the first water pump pumps the biogas slurry to the first anoxic tank, the anaerobic tank, and the integrated anaerobic ammonia oxidation reactor.

[0050] The second water pump pumps the sludge from the bottom of the primary sedimentation tank to the secondary anoxic tank.

[0051] The third water pump is used to return the effluent from the outlet of the integrated anaerobic ammonia oxidation reactor to the inlet of the integrated anaerobic ammonia oxidation reactor.

[0052] The fourth water pump pumps the solution in the aerobic tank to the secondary anoxic tank;

[0053] The fifth water pump pumps the sludge from the bottom of the secondary sedimentation tank to the primary pre-anoxic tank;

[0054] The first storage tank contains a calcium salt solution, which is then mixed into the outlet pipe of the primary sedimentation tank by the sixth water pump.

[0055] The second storage tank contains an alkaline solution, which is pumped into the integrated anaerobic ammonia oxidation reaction tank by the seventh water pump.

[0056] The third storage tank contains a carbon source solution, which is pumped into the secondary anoxic pool by the eighth water pump.

[0057] The raw water tank 1 pumps the anaerobic digestate from the aquaculture farm to the primary pre-anoxic tank 3, the anaerobic tank 5, and the integrated anaerobic ammonia oxidation reactor 9 via the inlet pump 2. The inlet ratios are 5-30%, 30-55%, and 40-65%, respectively. The primary pre-anoxic tank 3 is equipped with a first stirring device 4, and its bottom is connected to the anaerobic tank 5. The anaerobic tank 5 is equipped with a second stirring device 6, and its effluent flows by gravity to the primary sedimentation tank 7. The sludge settled at the bottom of the primary sedimentation tank 7 enters the secondary anoxic tank 12 via the second water pump 8. The first storage tank 20 (including a stirring device) is filled with a 10% calcium chloride solution, which is mixed with the effluent from the primary sedimentation tank 7 via the sixth water pump 21 and enters the integrated anaerobic ammonia oxidation reactor 9 from the bottom. The second storage tank 22 (including a stirring device) contains a sodium bicarbonate / sodium carbonate solution of a certain concentration, which is pumped into the inlet of the integrated anaerobic ammonia oxidation reactor 9 by the seventh water pump 23 to supplement alkalinity. The integrated anaerobic ammonia oxidation reactor 9 is equipped with a first aeration disc 10 to provide aeration. In addition, the effluent from the integrated anaerobic ammonia oxidation reactor 9 is returned to the inlet of the integrated anaerobic ammonia oxidation reactor 9 by the third water pump 11. The effluent from the top of the integrated anaerobic ammonia oxidation reactor 9 flows by gravity to the secondary anoxic tank 12. The third storage tank 24 (including a stirring device) contains a 30% sodium acetate solution, which provides an organic carbon source for denitrification in the secondary anoxic tank 12 by the eighth water pump 25. The bottom of the secondary anoxic tank 12 is connected to the aerobic tank 14, and a third stirring device 13 is installed inside. The aerobic tank is equipped with a second aeration disc 15, and aeration of both the aerobic tank and the integrated anaerobic ammonia oxidation reactor 9 is achieved through aeration blowers 17. The nitrified liquid from the aerobic tank 14 is returned to the secondary anoxic tank 12 via a fourth water pump 16. The effluent from the top of the aerobic tank 14 flows by gravity to the secondary sedimentation tank 18, and the supernatant is discharged after meeting the standards. The settled sludge is returned to the primary pre-anoxic tank 3 via a fifth water pump 19.

[0058] According to a third aspect of the present invention, the application of the anaerobic ammonia oxidation granular sludge denitrification and phosphorus removal method as described in the first aspect of the present invention in wastewater treatment is proposed.

[0059] According to a preferred embodiment of the present invention, at least the following beneficial effects are achieved:

[0060] 1. The biogas slurry is fed into the pre-anoxic tank and anaerobic tank separately to remove most of the organic matter in the influent, preventing excessive organic matter from entering the integrated anaerobic ammonia oxidation reactor. This is conducive to the subsequent denitrification coupling denitrification phenomenon in the anaerobic ammonia oxidation reactor, and the nitrate nitrogen generated by the anaerobic ammonia oxidation reaction will be removed by denitrification.

[0061] 2. By adding calcium-based compounds, the effective removal and recycling of phosphorus resources in wastewater can be achieved. The generated hydroxyapatite promotes the granulation of anaerobic ammonia oxidation sludge, making the system more resistant to shocks and able to handle higher loads.

[0062] 3. Compared with traditional nitrogen and phosphorus removal processes, biological phosphorus removal process removes some of the organic matter contained in biogas slurry, making the influent meet the requirements of anaerobic ammonia oxidation coupled with denitrification, and improving the total nitrogen removal rate of the anaerobic ammonia oxidation unit.

[0063] 4. Synchronous nitrogen and phosphorus removal is achieved by coupling anaerobic ammonia oxidation with nitrification and denitrification. Anaerobic ammonia oxidation removes most of the ammonia nitrogen, which can save carbon sources, reduce aeration energy consumption, and significantly reduce wastewater treatment costs. Attached Figure Description

[0064] The above and / or additional aspects and advantages of this invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0065] Figure 1 This is a diagram of the apparatus for the nitrogen and phosphorus removal method in Embodiment 1 of the present invention.

[0066] Figure label:

[0067] 1. Raw water tank; 2. First water pump; 3. Primary pre-anoxic tank; 4. First stirring device; 5. Anaerobic tank; 6. Second stirring device; 7. Primary sedimentation tank; 8. Second water pump; 9. Integrated anaerobic ammonia oxidation reactor; 10. First aeration disc; 11. Third water pump; 12. Secondary anoxic tank; 13. Third stirring device; 14. Aerobic tank; 15. Second aeration disc; 16. Fourth water pump; 17. Aeration blower; 18. Secondary sedimentation tank; 19. Fifth water pump; 20. First storage tank; 21. Sixth water pump; 22. Second storage tank; 23. Seventh water pump; 24. Third storage tank; 25. Eighth water pump. Detailed Implementation

[0068] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0069] Example 1

[0070] A method for cultivating calcium-based phosphorus fixation anaerobic ammonium oxidation granular sludge includes the following steps:

[0071] (1) Anaerobic fermentation slurry of aquaculture wastewater with ammonia nitrogen concentration of 1000 mg / L, COD of 1000 mg / L, BOD of 500 mg / L, and TP of 15 mg / L is stored in raw water tank 1 and pumped into a 90 L primary pre-anoxic tank 3 by the first water pump 2 at a flow rate of 2 L / h. The sludge returned from the secondary sedimentation tank 18 is simultaneously mixed into the primary pre-anoxic tank 3 by the fifth water pump 19 at a flow rate of 30 L / h, with a hydraulic retention time of 2.8 h. The primary pre-anoxic tank 3 is started by inoculating 30 L of denitrifying sludge with MLSS = 9000 mg / L and the first stirring device 4 is turned on to control the dissolved oxygen in the anoxic tank to be no higher than 0.6 mg / L for denitrification. After treatment in the primary pre-anoxic tank 3, the nitrate nitrogen in the effluent is less than 1 mg / L and enters the anaerobic tank 5 for phosphorus release and organic matter removal treatment.

[0072] (2) By adjusting the outlet valve of the first water pump 2, the flow rate of the anaerobic fermentation slurry of aquaculture wastewater pumped into the anaerobic tank 5 is controlled to be 4L / h. This portion of the slurry is mixed with the effluent from the first-stage pre-anoxic tank (32L / h) and enters the anaerobic tank 5 with an effective volume of 70L and a hydraulic retention time of 1.9h. 25L of ordinary anaerobic sludge with MLSS = 9000mg / L is inoculated to start the anaerobic tank 5. The frequency of the second stirring device 6 is adjusted to control the dissolved oxygen in the water to be below 0.2mg / L. The effluent TP and BOD are measured. If the effluent TP gradually increases and the BOD gradually decreases, the anaerobic tank 5 is considered to have started successfully and the phosphorus release effect is stable. After successful acclimation, the effluent from the anaerobic tank has an ammonia nitrogen of about 150-200mg / L, a total phosphorus of about 6-9mg / L, and almost no BOD. The effluent from the anaerobic tank 5 is then allowed to flow by gravity into the first-stage sedimentation tank 7 to achieve sludge-water separation. After the sludge at the bottom of the primary sedimentation tank 7 is settled and concentrated, it is pumped into the secondary anoxic tank 12 via the second water pump 8 to maintain the MLSS (mixed sludge concentration) of the secondary anoxic and aerobic tanks at 3000-3500 mg / L. In addition, some sludge is periodically discharged to control the sludge age of the entire system within the range of 4-7 days.

[0073] (3) By adjusting the outlet valve of the first water pump 2, the flow rate of the anaerobic fermentation slurry of the livestock wastewater pumped into the anaerobic tank 5 is controlled to be 4L / h. This part of the slurry is mixed with the effluent from the primary sedimentation tank 7 flowing by gravity and enters the integrated anaerobic ammonia oxidation reactor 9 with an effective volume of 100L. A 10% calcium chloride solution is stored in the first storage tank 20. By controlling the flow rate of the sixth water pump 21, the calcium ion addition is controlled to be 30mg / L to make the calcium:phosphorus mass ratio 3:1, which accelerates the formation of hydroxyapatite crystal nuclei. The integrated anaerobic ammonia oxidation reactor 9 is started by inoculating 20L LMLSS=9000mg / L mature anaerobic ammonia oxidation flocculent sludge. A sodium bicarbonate solution or sodium carbonate solution is stored in the second storage tank 22 and pumped into the integrated anaerobic ammonia oxidation reactor 9 through the seventh water pump 23 to supplement the required alkalinity and control the pH value of the water between 7.5 and 8.3. Controlling the return flow rate of the third water pump 11 in the reaction tank, so that the internal return upward flow velocity is adjusted to within 4m / h, is more conducive to the formation of granular sludge.

[0074] (4) Turn on the aeration blower 17. The air volume of the first aeration disc 10 is adjusted based on the dissolved oxygen in the effluent, and the dissolved oxygen in the effluent is controlled within the range of 0.5 to 5 mg / L. Under the premise of controlling the above conditions, the denitrification effect of anaerobic ammonia oxidation coupled with denitrification occurs in the integrated anaerobic ammonia oxidation reactor 9. The ammonia nitrogen in the influent of the integrated anaerobic ammonia oxidation reactor 9 is removed by anaerobic ammonia oxidation, the organic matter contained in the influent biogas slurry is removed by coupled denitrification, and the small amount of nitrate nitrogen produced by anaerobic ammonia oxidation is removed.

[0075] (5) The total phosphorus in the effluent from the integrated anaerobic ammonia oxidation reactor 9 is approximately 3-4 mg / L, the ammonia nitrogen is approximately 50 mg / L, and the total nitrogen is approximately 60 mg / L. The effluent enters the downstream secondary anoxic tank-aerobic tank for further denitrification treatment to meet standards. The return flow rate of the fourth water pump 16 is controlled at 35 L / h. The effective volume of the secondary anoxic tank 12 is 150 L. The hydraulic retention time is controlled at 2.5 h. The secondary anoxic tank 12 is started by inoculating 50 LMLSS = 9000 mg / L ordinary denitrification sludge and turning on the third stirring device 13. The dissolved oxygen in the secondary anoxic tank 12 is controlled to be no higher than 0.6 mg / L. Sodium acetate solution is stored in the third storage tank 24. The organic carbon source is supplemented to the secondary anoxic tank 12 through the eighth water pump 25. The carbon source addition flow rate is appropriately increased or decreased according to the total nitrogen and COD of the effluent, so that the total nitrogen of the effluent is less than 15 mg / L and the COD of the effluent is less than 50 mg / L.

[0076] (6) The effective volume of aerobic tank 14 is 240L. At startup, 80L of ordinary nitrifying sludge is inoculated, with a sludge concentration of 9000mg / L. The hydraulic retention time is controlled at 4–6 hours, and the gas production of the second aeration disc 15 is adjusted to maintain the dissolved oxygen in aerobic tank 14 within the range of 2–4mg / L. When the effluent ammonia nitrogen decreases to below 5mg / L and the effluent total phosphorus decreases to around 0.5mg / L, it indicates that the nitrogen and phosphorus removal effect is good under aerobic conditions.

[0077] (7) After the effluent from the aerobic tank 14 is settled in the secondary sedimentation tank 18, the ammonia nitrogen in the supernatant is less than 5 mg / L, the total nitrogen is less than 15 mg / L, and the total phosphorus is less than 0.5 mg / L, which meets the discharge standards. The bottom sediment is returned to the primary pre-anoxic tank 3, and steps (1) to (6) are repeated for nitrogen and phosphorus removal treatment.

[0078] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for nitrogen and phosphorus removal from anaerobic ammonia oxidation granular sludge, characterized in that, The process flow is as follows: (1) The raw biogas slurry is fed into three separate locations: a primary pre-anoxic tank, an anaerobic tank, and an integrated anaerobic ammonia oxidation reactor. The bottom of the primary pre-anoxic tank is connected to the anaerobic tank. Returned sludge is also fed into the primary pre-anoxic tank. (2) The effluent from the anaerobic tank is sent to the primary sedimentation tank, the clear liquid from the upper layer of the primary sedimentation tank is sent to the integrated anaerobic ammonia oxidation reactor, and the sludge at the bottom of the primary sedimentation tank is pumped into the secondary anoxic tank. (3) Calcium salt is added to the integrated anaerobic ammonia oxidation reactor to form hydroxyapatite crystal nuclei and accelerate the formation of anaerobic ammonia oxidation granular sludge. Alkali solution is added to control the pH value in the reactor to 7.5~8.

3. (4) The effluent from the integrated anaerobic ammonia oxidation reactor is sent to the secondary anoxic tank, and the bottom of the secondary anoxic tank is connected to the aerobic tank; the effluent from the aerobic tank is sent to the secondary sedimentation tank, the upper clear liquid of the secondary sedimentation tank is discharged after meeting the standards, and the bottom sludge is returned to the primary pre-anoxic tank; The process involves stirring in the primary pre-anoxic tank, the anaerobic tank, and the secondary anoxic tank, aeration in the integrated anaerobic ammonia oxidation reactor and the aerobic tank, controlling the dissolved oxygen in the effluent of the integrated anaerobic ammonia oxidation reactor to be 0.5-5 mg / L, and the occurrence of denitrification coupled with nitrogen removal in the integrated anaerobic ammonia oxidation reactor. The COD / ammonia nitrogen concentration ratio of the influent to the integrated anaerobic ammonia oxidation reactor is <0.3; The process parameters for the raw biogas slurry are: ammonia nitrogen concentration of 500. 2000 mg / L, COD is 1000 4000 mg / L, BOD is 500 3000 mg / L, TP is 3 25mg / L.

2. The anaerobic ammonia oxidation granular sludge denitrification and phosphorus removal method according to claim 1, characterized in that, In step (1), the proportions of raw biogas slurry fed into the primary pre-anoxic tank, anaerobic tank and integrated anaerobic ammonia oxidation reactor are 5-30%, 30-55% and 40-65%, respectively.

3. The anaerobic ammonia oxidation granular sludge denitrification and phosphorus removal method according to claim 1, characterized in that, Calcium salts are added to the integrated anaerobic ammonia oxidation reactor, and the mass ratio of calcium to total phosphorus in the influent of the integrated anaerobic ammonia oxidation reactor is controlled to be (3-5):

1.

4. The anaerobic ammonia oxidation granular sludge denitrification and phosphorus removal method according to claim 1, characterized in that, Use a reflux pump to adjust the upward flow velocity in the integrated anaerobic ammonia oxidation reactor to 1.5-6 m / h.

Images