One-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation device and method

Abstract

The present invention discloses a one-stage partial nitrite-anaerobic ammonia oxidation micro-granular sludge cultivation device and method, the device includes an aeration system, a water inlet system, a reactor, an indicator monitoring system, and a temperature control system. After the inoculated sludge is placed in the reactor, raw water is continuously flowed into the reactor and continuously aerated to maintain a micro-oxygen environment in the reactor, and the sludge in the reactor is completely mixed with the inlet water until mature micro-granular sludge is formed. The beneficial effects of the present invention are: the device is simple, the system denitrification performance is stable and effective; by controlling the DO concentration of the mixed solution in the reaction unit and continuously improving the gas shear force and ammonia nitrogen load, a micro-granular sludge that can achieve synchronous partial nitrite and anaerobic ammonia oxidation is cultivated, and the micro-granular sludge has good sedimentation performance.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and specifically relates to a one-stage partial nitrite-anaerobic ammonia oxidation micro-granular sludge cultivation device and method, which is suitable for the treatment of ammonia nitrogen-containing sewage. Background Art

[0002] Since anaerobic ammonium oxidation (Anammox) has the advantages of not requiring an organic carbon source and producing less sludge, technologies and processes based on Anammox have received widespread attention in the field of biological denitrification of wastewater. This technology is often used in conjunction with traditional denitrification technology to greatly improve the denitrification efficiency. Among them, partial nitritation-anaerobic ammonium oxidation process (PNA, Partial nitritation / anammox) is the main way to treat urban sewage. The process is mainly divided into two steps. First, ammonia oxidizing bacteria (AOB, Ammonium oxidation bacteria) partially oxidize ammonia nitrogen to nitrite nitrogen under aerobic or microaerobic conditions. After that, anaerobic ammonium oxidizing bacteria (AnAOB, Anaerobic ammonium oxidation bacteria) use nitrite nitrogen as an electron acceptor to oxidize the remaining ammonia nitrogen and generate nitrogen gas. The single-stage partial nitrite-anaerobic ammonium oxidation (SPNA, single-stage PNA) process has more advantages due to its short process flow, low operating costs and small footprint. This process has become a research hotspot in this field at home and abroad. The SPNA microgranular sludge system, in addition to the advantages of not requiring a carbon source and low energy consumption, also has the characteristics of good sludge settling performance and high microbial biomass. In the SPNA microgranular sludge, AOB and AnAOB work together to achieve autotrophic removal of ammonia nitrogen-containing wastewater. First, the AOB on the microparticles oxidizes the ammonia nitrogen in the water into nitrite nitrogen, and then the AnAOB on the microparticles converts ammonia nitrogen and nitrite nitrogen into gaseous nitrogen, thereby realizing the autotrophic biological denitrification process of sewage. In the one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge system, AOB and AnAOB coexist on the microgranules through flocculation. The nitrite nitrogen produced by AOB can be quickly utilized by AnAOB, so the reaction is rapid. More importantly, this type of microparticle has good sedimentation properties, which makes mud and water separation simple and easy, greatly reducing the footprint of the reactor.

[0003] At present, the SPNA process can be realized by suspended sludge method, granular sludge method and biofilm method, among which the biofilm method is the most widely used. However, the process of SPNA microparticles is very rare. According to the currently available literature, it is difficult to cultivate SPNA granular sludge, so it is necessary to develop methods and devices for effectively cultivating SPNA microparticle sludge.

[0004] Granular sludge is a granular aggregate formed by microorganisms through coagulation. The operating conditions of the system (such as changes in the influent load, etc.) will affect the formation of sludge particles. The formation of granular sludge can only be formed under harsh conditions, such as: the reactor requires a specific organic load, hydraulic shear force, nutrients, hydraulic retention time operation mode, or needs to provide a carrier, prevent toxic substances from interfering, and other factors. If the hydraulic shear force is too small, it will not promote particle formation, and if it is too large, it will destroy the particle structure; the nutrients provided are mainly ammonia nitrogen. If the ammonia nitrogen is too low, the cultivation effect of SPNA microgranular sludge is not good. If it is too high, the free ammonia in the system will increase, which will inhibit the microorganisms in the reactor, and even destroy the entire reaction system in severe cases. These conditions are also the focus of current research. At present, there are many studies on the mechanism of granular sludge formation, and there are also studies on the method of granular sludge formation. However, there is no cultivation device and method for microgranular sludge with one-stage partial nitrite-anaerobic ammonia oxidation function. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a device and method for cultivating micro-granular sludge with partial nitrite and anaerobic ammonium oxidation functions under continuous flow conditions. In this device, by controlling the gas supply in the continuous flow reactor, on the one hand, a suitable DO concentration is maintained, and on the other hand, a suitable hydraulic shear force can be maintained to promote the formation of micro-granular sludge, and finally partial nitrite and anaerobic ammonium oxidation can be achieved in the same continuous flow reactor for a long time, and finally efficient and stable denitrification can be achieved.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a one-stage partial nitrite-anaerobic ammonia oxidation microgranular sludge cultivation device, comprising: an aeration system, a water inlet system, a reactor, an index monitoring system, and a temperature control system, wherein the aeration system comprises an aeration pump, a gas flowmeter, and an air inlet pipe arranged in sequence; the water inlet system comprises a raw water bucket, a peristaltic pump, and a connecting pipeline; the reactor comprises a reaction unit and a precipitation unit, a vertical partition is provided in the reaction unit, a partition is provided between the reaction unit and the precipitation unit and is connected at the lower part, and an inclined plate is provided at the bottom of the precipitation unit located in the reaction tank; the index monitoring system comprises a DO monitor located in the reaction unit and a pH monitor located in the precipitation unit, and the temperature control system comprises a constant temperature bath; one end of the air inlet pipe is located at the bottom of the reaction unit, and the precipitation unit is provided with a pipeline connected to the constant temperature bath.

[0007] The reaction unit is provided with a vertical partition, the length of which is 0.5 to 0.6 times the effective water depth of the reaction unit, and the distance between the partition and the bottom of the reaction unit is 0.4 to 0.5 times its own length.

[0008] The diameter of the air outlet hole of the air inlet pipe is 2 to 5 mm.

[0009] The inclination angle of the inclined plate is between 60° and 70°.

[0010] An air inlet pipe is installed in the reaction unit, which provides bubbles with a diameter of 2 to 6 mm to form an internal circulation gas in the reaction unit. Under the driving force of the internal circulation gas, the mixed liquid is refluxed and fully mixed in the reaction unit. The sedimentation unit is provided with an inclined plate with an inclination angle of 60 to 70 degrees, which is used for mud and water separation on the one hand, and can also prevent the loss of sludge when the initial sedimentation is poor on the other hand; air is supplied to the bottom of the reaction zone by an aeration pump through a fixed air inlet pipe to provide continuous circulation gas driving force and oxygen diffusion, and the gas supply is adjusted by a gas flow meter. The raw water is transferred to the reactor through a peristaltic pump; the temperature of the mixed liquid in the reactor is controlled at 30±1℃ by a thermostatic bath. The dissolved oxygen concentration of the mixed liquid in the reaction unit and the pH value of the water in the sedimentation unit are regularly measured using a dissolved oxygen monitor and a pH monitor. During the entire operation, the pH of the water in the sedimentation unit is maintained within the range of 8.0±0.3.

[0011] The present invention also provides a one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation method, which uses the one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation device and comprises the following steps:

[0012] Step 1, sludge inoculation and startup stage: first inoculate the reactor with suspended sludge with traditional nitrification and denitrification functions, at which time the sludge concentration in the reaction unit is 3800-4500 mg / L; then add anaerobic ammonium oxidation inoculation sludge, so that the sludge concentration in the reaction unit is 4000-5000 mg / L MLSS;

[0013] Step 2, operation stage: after the inoculated sludge is placed in the reactor, raw water is continuously flowed into the reactor and aeration is continuously performed, the gas superficial rising velocity in the reaction unit is 1.0-1.5 cm / s, the DO concentration of the mixed liquid in the reaction unit is between 0.03-0.10 mg / L, so that a micro-oxygen environment is maintained in the reactor, and the sludge in the reactor is completely mixed with the influent until micro-particle sludge is formed.

[0014] The original operation process of the anaerobic ammonium oxidation inoculum sludge in step 1 is an upflow anaerobic sludge blanket process, which operates at 30-32°C, the influent ammonia nitrogen concentration is 90-110 mg / L, the DO is lower than 0.5 mg / L, the sludge concentration of the anaerobic ammonium oxidation inoculum sludge is 7500-8500 mg / L, and the volume of the inoculum sludge added is 5%-10% of the effective volume of the reaction unit.

[0015] In step 2, the ammonia nitrogen concentration of the raw water is 100-400 mg / L, the total phosphorus concentration is 15-25 mg / L, and the average residence time of the raw water in the reactor is 6 hours.

[0016] The ammonia nitrogen concentration of the raw water gradually increases from 100 mg / L to 400 mg / L as the operation time increases.

[0017] 9. The one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation method according to claim 8 is characterized in that, on the 1st to 15th day, the raw water ammonia nitrogen concentration is 100 mg / L; on the 15th to 35th day, the raw water ammonia nitrogen concentration is 150 mg / L; on the 35th to 40th day, the raw water ammonia nitrogen concentration is 200 mg / L; on the 40th to 110th day, the raw water ammonia nitrogen concentration is 250 mg / L; on the 110th to 160th day, the raw water ammonia nitrogen concentration is 275 mg / L; on the 160th to 180th day; the raw water ammonia nitrogen concentration is 300 mg / L, on the 180th to 195th day, the raw water ammonia nitrogen concentration is 350 mg / L; on the 195th to 205th day, the raw water ammonia nitrogen concentration is 400 mg / L.

[0018] During the operation of the reactor, the gas superficial rising velocity in the reaction unit is 1.0-1.5 cm / s, the DO concentration of the mixed solution is maintained between 0.03-0.10 mg / L, the temperature is controlled at 30±1°C, and the pH value of the water in the precipitation unit is maintained at 8.0±0.3.

[0019] After the inoculated sludge is placed in the reactor, raw water is continuously introduced into the reactor and aeration is continuously performed. Under the driving force of the internal circulation gas, the mixed liquid can be completely mixed in the reaction unit until micro-granular sludge is formed; the DO concentration of the mixed liquid in the reaction unit is controlled by controlling the gas supply volume, so that the reaction unit maintains a micro-oxygen environment, and the hydraulic shear force in the reaction unit can also be controlled within a certain range; by increasing the ammonia nitrogen concentration of the raw water in a step-by-step manner, the nitrogen load of the reactor inlet water is gradually increased, and at the same time, the gas supply volume is gradually increased to maintain a suitable DO concentration of the mixed liquid in the reaction unit, and the hydraulic shear force is gradually increased, thereby accelerating the formation of micro-granular sludge; the cultivation method and device can form SPNA micro-granular sludge with an average particle size of 0.2 to 0.3 mm within 200 days, and mature SPNA micro-granular sludge with good sedimentation performance, clear outer contour, ammonia nitrogen removal rate of more than 85%, and total nitrogen removal rate of more than 75%.

[0020] The beneficial effects of the present invention are as follows: by controlling the DO concentration of the mixed liquid in the reaction unit and continuously increasing the gas shear force and the ammonia nitrogen load, a micro-granular sludge that can achieve synchronous partial nitrite and anaerobic ammonia oxidation is cultivated, the granular sludge has good sedimentation performance, the device is simple, and the system denitrification performance is stable and effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is a schematic structural diagram of the SPNA microgranular sludge reactor in the first embodiment of the present invention;

[0022] Figure 2 This is a particle size distribution diagram of SPNA microgranular sludge when cultured to the 90th day in the second embodiment of the present invention;

[0023] Figure 3 This is a particle size distribution diagram of SPNA microgranular sludge when cultured to the 205th day in the second embodiment of the present invention;

[0024] Figure 4 This is a graph showing particle size changes during operation of the SPNA microgranular sludge reactor in the second embodiment of the present invention;

[0025] Figure 5 This is a photo of mature SPNA microgranular sludge in the second embodiment of the present invention;

[0026] Figure 6 This is an electron microscope image of the mature SPNA microgranular sludge formed in the second embodiment of the present invention.

[0027] In the figure:

[0028] 1. Aeration pump 2. Gas flow meter 3. Inlet pipe

[0029] 4. Raw water bucket 5. Peristaltic pump 6. DO monitor

[0030] 7. pH monitor 8. Constant temperature bath

[0031] Ⅰ. Reaction unit Ⅱ. Precipitation unit DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0033] like Figure 1 As shown, a one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation device includes: an aeration system, a water inlet system, a reactor, an indicator monitoring system, and a temperature control system. The reactor is provided with a reaction unit and a sedimentation unit. The aeration system includes an aeration pump, a gas flow meter, and an air inlet pipe. The air inlet pipe is made of plexiglass; the water inlet system includes a raw water bucket and a peristaltic pump; the indicator monitoring system includes: a DO monitor and a pH monitor; the temperature control system is mainly a constant temperature tank.

[0034] The reaction unit is equipped with an air inlet pipe, which provides bubbles to completely mix the mixed liquid in the reaction unit. The sedimentation unit is equipped with an inclined plate, and the inclined angle of the inclined plate is between 60 and 70 degrees. Driven by the driving force of the internal circulation gas, the mixed liquid circulates in the reaction unit and is fully mixed.

[0035] Air is supplied to the bottom of the reaction unit by an aeration pump through a fixed air inlet pipe to provide continuous internal circulation gas driving force and oxygen diffusion. The gas supply is adjusted by a gas flow meter. The raw water is transferred to the reaction unit by a peristaltic pump. The temperature of the mixed liquid in the reactor is mainly controlled by a thermostatic water bath device. The dissolved oxygen concentration of the mixed liquid in the reaction zone and the pH value of the water in the precipitation unit are regularly measured using a dissolved oxygen monitor and a pH monitor.

[0036] The one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation method of the present invention comprises the following steps:

[0037] 1) Sludge inoculation and startup phase

[0038] First, suspended sludge with traditional nitrification and denitrification functions is inoculated, and then anaerobic ammonia oxidation sludge is inoculated, so that the MLSS sludge concentration of the mixed liquor in the reaction unit is 4000-5000 mg / L.

[0039] 2) Operation phase

[0040] After the inoculated sludge is placed in the reactor, raw water is continuously introduced into the reactor and aeration is continuously performed to maintain a micro-oxygen environment in the reactor and to completely mix the sludge in the reactor with the influent water until micro-granular sludge is formed.

[0041] Example 1

[0042] A one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation device comprises five parts: an aeration system, a water inlet system, a reactor, an index monitoring system and a temperature control system. The aeration system comprises an aeration pump, a gas flow meter and an air inlet pipe connected in series. The water inlet system comprises a raw water bucket and a peristaltic pump. The reactor comprises a reaction unit and a precipitation unit. The index monitoring system comprises a DO monitor and a pH monitor. The temperature control system is a constant temperature tank.

[0043] The reactor is 700mm high, 500mm wide and has an effective volume of 8L. The raw water is taken from the raw water barrel 3 and transferred to the reaction unit through the peristaltic pump 4. When the aeration pump 1 starts to run, the air passes through the gas flow meter 2 and supplies gas to the mixed liquid in the reaction unit through the air inlet pipe 3 to provide continuous internal circulation gas driving force and oxygen diffusion, so that the mixed liquid in the reaction unit is completely mixed, and the gas supply is adjusted by the gas flow meter 2. The sedimentation unit is provided with an inclined plate area with an inclination angle between 60 and 70° to separate mud and water and prevent sludge loss. The dissolved oxygen concentration in the reaction unit and the pH value of the sedimentation unit are monitored in real time by the dissolved oxygen monitor 6 and the pH monitor 7. The temperature of the mixed liquid in the reaction unit is controlled by using a thermostatic bath 8 to keep the temperature of the mixed liquid in the reaction unit at 30±1°C.

[0044] Example 2

[0045] A one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation method, which uses the one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation device of Example 1, comprising the following steps:

[0046] In the reactor of the device, 7300mL of suspended sludge with MLSS of 4300mg / L and traditional nitrification and denitrification functions is first inoculated, and then 700mL of anaerobic ammonia oxidation sludge with MLSS of 8000mg / L is inoculated. The raw water is prepared by itself, and the ammonia nitrogen concentration is 100-400mg / L, and the total phosphorus concentration is in the range of 15-25mg / L. After the inoculated sludge is placed in the reactor, the raw water enters from the upper part of the reaction unit of the reactor. The average residence time of the raw water in the reactor is 6h, that is, the water entering the reactor is renewed 4 times a day. Raw water is introduced into the reactor and gas is continuously supplied. The apparent rising velocity of the gas in the reaction unit is in the range of 1.0-1.5cm / s, so that the mixed liquid in the reaction unit maintains a micro-oxygen environment (DO=0.03-0.06mg / L). Driven by the driving force of the internal circulation gas, the mixed liquid is completely mixed in the reaction unit. Before the 110th day, the sludge particle size did not increase significantly. Figure 2 On the 110th day, SPNA microgranular sludge was initially formed in the reactor, with an average particle size of 0.15 mm; on the 160th to 180th day, the ammonia nitrogen concentration was 300 mg / L, the particle size of SPNA microgranular sludge gradually increased, and the sedimentation performance was further improved; on the 180th to 195th day, the ammonia nitrogen concentration was 350 mg / L, and the particle size of SPNA microgranular sludge increased further; on the 195th to 205th day, the ammonia nitrogen concentration of the raw water was 400 mg / L, Figure 3 As shown in the figure, the microgranular sludge with a particle size between 0.50 and 0.84 mm accounts for 41% of the total sludge; and the average particle size of the sludge increases to 247 μm, and mature SPNA microgranular sludge is formed in the reactor, such as Figure 4 shown.

[0047] Figure 5 The mature SPNA microgranular sludge formed by the culture in this embodiment is shown in FIG. The shape is round or oval, and the particle color is red. Figure 6 The electron microscope image of the microgranular sludge shows that the surface of the granular sludge is full of pores, which is conducive to the transfer of nutrients and microbial metabolism. Dissolved oxygen enters the interior of the AnAOB-enriched granules from the outer surface of the AOB-enriched granular sludge through mass transfer, forming a dissolved oxygen gradient, forming an aerobic zone outside the granular sludge, and an anaerobic or anoxic zone inside, which is conducive to enhancing the denitrification performance of microorganisms.

[0048] After the micro-granular sludge is successfully cultivated, the total nitrogen removal rate of raw water can reach more than 80% and the ammonia nitrogen removal rate can reach more than 90% during the stable operation period.

[0049] The above is a detailed introduction to the SPNA microgranular sludge cultivation method and cultivation device provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation method, characterized in that: The steps include: Step 1, sludge inoculation and startup stage: first inoculate the reactor with suspended sludge with traditional nitrification and denitrification functions, at which time the sludge concentration in the reaction unit is 3800-4500 mg / L; then add anaerobic ammonium oxidation inoculation sludge, so that the sludge concentration in the reaction unit is 4000-5000 mg / L MLSS; Step 2, operation stage: after the inoculated sludge is placed in the reactor, raw water is continuously introduced into the reactor and aerated continuously, the gas superficial rising velocity in the reaction unit is 1.0-1.5 cm / s, the DO concentration of the mixed liquid in the reaction unit is between 0.03-0.10 mg / L, so that the reactor maintains a micro-oxygen environment, and the sludge in the reactor is completely mixed with the influent until micro-particle sludge is formed; the ammonia nitrogen concentration of the raw water is 100-400 mg / L, the total phosphorus concentration is 15-25 mg / L, and the average residence time of the raw water in the reactor is 6h; the ammonia nitrogen concentration of the raw water gradually increases from 100 mg / L to 400 mg / L with the operation time; from the 1st to the 15th day, the ammonia nitrogen concentration of the raw water is 100 mg / L; from the 15th to the 35th day, the ammonia nitrogen concentration of the raw water is 150 mg / L; from the 35th to the 40th day, the ammonia nitrogen concentration of the raw water is 200 mg / L; on the 40th to 110th day, the ammonia nitrogen concentration of the raw water is 250 mg / L; on the 110th to 160th day, the ammonia nitrogen concentration of the raw water is 275 mg / L; on the 160th to 180th day; the ammonia nitrogen concentration of the raw water is 300 mg / L, on the 180th to 195th day, the ammonia nitrogen concentration of the raw water is 350 mg / L; on the 195th to 205th day, the ammonia nitrogen concentration of the raw water is 400 mg / L.

2. The one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation method according to claim 1, characterized in that: The original operation process of the anaerobic ammonium oxidation inoculum sludge in step 1 is an upflow anaerobic sludge blanket process, which operates at 30-32°C, with an influent ammonia nitrogen concentration of 90-110 mg / L, a DO lower than 0.5 mg / L, and a sludge concentration of the anaerobic ammonium oxidation inoculum sludge of 7500-8500 mg / L. The volume of the inoculum sludge added is 5%-10% of the effective volume of the reaction unit.

3. The one-stage partial nitrite-anaerobic ammonium oxidation microgranular sludge cultivation method according to claim 2, characterized in that: During the operation of the reactor, the gas superficial upward velocity in the reaction unit is 1.0-1.5 cm / s, the DO concentration of the mixed solution is maintained between 0.03-0.10 mg / L, the temperature is controlled at 30±1°C, and the pH value of the water in the precipitation unit is maintained at 8.0±0.3.

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