Series carrier-coupled membrane aeration biofilm reactor and use method thereof

Abstract

The present application provides a series carrier-coupled membrane aeration biofilm reactor and a method for using the same. The series carrier-coupled membrane aeration biofilm reactor comprises at least two stages of membrane aeration biofilm reactor bodies arranged in series, and the membrane aeration biofilm reactor body comprises a tank body, a membrane assembly and a coupling carrier. The tank body comprises a water inlet and a water outlet, and the water outlet of the Nth stage membrane aeration biofilm reactor body is connected to the water inlet of the N+1th stage membrane aeration biofilm reactor body, where N≥1 and is an integer. The membrane assembly comprises a plurality of hollow fiber membrane filaments. Anaerobic ammonia-oxidizing bacteria are enriched in the coupling carrier, and the coupling carrier is used to be arranged on the outside of the membrane assembly, and the membrane assembly and the coupling carrier are arranged in the tank body. The method for using the series carrier-coupled membrane aeration biofilm reactor comprises performing short-range nitrification through the membrane assembly before adding the coupling carrier; and adding the coupling carrier on which the anaerobic ammonia-oxidizing bacteria have completed biofilm formation.

Description

Technical Field

[0001] The present application relates to the treatment of water, wastewater, sewage or sludge, and in particular to a series carrier-coupled membrane aeration biofilm reactor and a method for using the same. Background Art

[0002] Membrane-aerated biofilm reactor (MABR) is a new type of sewage treatment process. It can use hollow fiber membrane components to transfer oxygen to aqueous solutions without bubbles. At the same time, it can use the biofilm formed on the surface of the hollow fiber membrane (aeration membrane) to degrade pollutants in sewage. The air supply pressure required for bubble-free aeration is low, and the oxygen utilization efficiency is high, which can effectively reduce the aeration energy consumption of sewage treatment processes. In addition, Figure 2 As shown in (a), due to the transfer of oxygen from the membrane material to the solution, the biofilm can realize a layered structure of aerobic zones and anoxic zones from the inside to the outside. The inner aerobic zone and the outer anoxic zone are conducive to the growth of nitrifying bacteria and denitrifying bacteria, respectively, and can realize integrated nitrification and denitrification, which has good application prospects in the field of sewage denitrification.

[0003] At present, the MABR nitrification and denitrification technology for domestic sewage has been initially applied. If the denitrification pathway can be further optimized and the MABR is combined with the short-term nitrification-anaerobic ammonium oxidation process, the aeration energy consumption and carbon source dosage of the denitrification process can be further reduced, and the advantages of MABR in energy saving and consumption reduction can be better utilized. However, the short-term nitrification-anaerobic ammonium oxidation process based on MABR currently has problems such as low denitrification rate, poor effluent quality and unstable operation.

[0004] The patent with publication number CN101538087A discloses a method for realizing short-range nitrification-anaerobic ammonium oxidation denitrification using MABR. This method uses non-woven fabric to wrap microporous aeration carbon tubes, and both nitrifying bacteria and anaerobic ammonium oxidizing bacteria grow on the non-woven fabric filler, that is, near the surface of the hollow fiber membrane. In actual operation, the inner layer of the biofilm is aerobic nitrifying bacteria, and the outer layer is anaerobic ammonium oxidizing bacteria. The traditional MABR represented by this patent has two major defects in realizing the short-range nitrification-anaerobic ammonium oxidation denitrification function.

[0005] First, the anaerobic biofilm (or outer anoxic zone, outer layer of the biofilm) hinders the mass transfer of ammonia nitrogen, resulting in a low denitrification rate of the device or a high ammonia nitrogen concentration in the effluent. Since the denitrification process is divided into two steps: short-term nitrification and anaerobic ammonia oxidation, short-term nitrification occurs in the aerobic zone of the inner layer of the biofilm, and nitrifying bacteria use the oxygen transferred by the membrane material to oxidize ammonia nitrogen into nitrite. The rate of short-term nitrification is related to the ammonia nitrogen concentration in the inner layer of the biofilm. When the ammonia nitrogen concentration in the inner layer of the biofilm is lower than 5 mg-N / L (milligrams of nitrogen per liter), the short-term nitrification rate will be significantly inhibited, thereby reducing the overall denitrification rate.

[0006] The ammonia nitrogen concentration in the inner layer of the biofilm depends on the ammonia nitrogen concentration in the main solution and the mass transfer resistance of ammonia nitrogen from the main solution to the inner layer of the biofilm. Among them, when treating municipal sewage, in order to meet the requirements of ammonia nitrogen effluent indicators, the ammonia nitrogen concentration in the main solution of the integrated MABR needs to be lower than 5 mg-N / L, so that the ammonia nitrogen concentration in the inner layer of the biofilm is also lower than 5 mg-N / L. On the other hand, the mass transfer resistance from the main solution to the inner layer of the biofilm mainly includes the mass transfer resistance of the anaerobic biofilm. In traditional MABR, anaerobic ammonia oxidizing bacteria are enriched in anaerobic biofilms. Due to the low utilization rate of the substrate of anaerobic ammonia oxidizing bacteria, the denitrification process has a relatively large demand for the biomass of anaerobic ammonia oxidizing bacteria, that is, the thickness of the anaerobic biofilm layer dominated by anaerobic ammonia oxidizing bacteria is large, and the resistance to ammonia nitrogen mass transfer is also large. In addition, the anaerobic ammonia oxidizing bacteria themselves need to consume ammonia nitrogen, so the anaerobic biofilm will further reduce the ammonia nitrogen concentration in the aerobic zone. Therefore, when the ammonia nitrogen concentration in the main solution is about 5 mg-N / L, the ammonia nitrogen concentration in the inner layer of the membrane aeration biofilm will drop to below 1 mg-N / L, which will strongly inhibit the nitrification rate and greatly reduce the denitrification rate.

[0007] The patent with publication number CN101538087A has an ammonia nitrogen conversion rate of 88.7% under the condition of an influent ammonia nitrogen concentration of 200 mg-N / L, that is, the effluent ammonia nitrogen is as high as 22.6 mg-N / L. This is because the ammonia nitrogen mass transfer resistance is too high, so the effluent ammonia nitrogen concentration must be maintained at more than 20 mg-N / L to maintain a suitable nitrification rate, and it is impossible to simultaneously ensure a high denitrification rate and a low effluent ammonia nitrogen concentration. According to relevant research papers (References 1~5, see below for details), when the influent ammonia nitrogen concentration is about 50 mg-N / L, the effluent ammonia nitrogen concentration of the traditional MABR under the short-range nitrification-anaerobic ammonia oxidation process can only reach about 5 mg-N / L, which cannot stably reach the municipal sewage Class A standard (Pollutant Discharge Standard for Urban Wastewater Treatment Plants, GB 18918-2002, the same below), the hydraulic retention time is more than 12 hours, and the denitrification rate is low. Therefore, the treated water quality and denitrification rate of the MABR short-range nitrification-anaerobic ammonium oxidation process need to be improved and enhanced.

[0008] Secondly, when the effluent ammonia nitrogen concentration is low, it is difficult for MABR to maintain the inhibition of nitrite oxidizing bacteria (NOB) and cannot maintain a long-term stable denitrification effect. NOB will oxidize nitrite to nitrate, making nitrite unusable by anaerobic ammonia oxidizing bacteria, reducing the total nitrogen removal rate of the system. Therefore, in order to maintain a stable short-range nitrification-anaerobic ammonia oxidation process, it is possible to choose to inhibit the activity of NOB. In MABR, NOB inhibition is mainly achieved by the competition between ammonia oxidizing bacteria (AOB) and NOB for oxygen. Therefore, in order to inhibit NOB activity, in addition to controlling the supply of oxygen, it is also necessary to maintain a high AOB activity. When the effluent ammonia nitrogen concentration is low (for example, less than 5 mg-N / L), AOB activity begins to be inhibited, and NOB activity may increase, thereby reducing the total nitrogen removal rate.

[0009] The patent with publication number CN101538087A shows that the total nitrogen concentration in the effluent is as high as 48.65 mg-N / L when the influent ammonia nitrogen concentration is 200 mg-N / L. According to relevant research papers (References 1~5), when the influent ammonia nitrogen concentration is about 50 mg-N / L, the total nitrogen concentration in the effluent of the traditional MABR under the short-term nitrification-anaerobic ammonium oxidation process can only reach about 15 mg-N / L, which cannot stably reach the municipal sewage Class A standard. Therefore, corresponding NOB inhibition methods need to be developed in the MABR short-term nitrification-anaerobic ammonium oxidation process.

[0010] literature

[0011] Reference 1: Li X, Sun S, Badgley BD, et al. Nitrogen removal by granularnitritation-anammox in an upflow membrane-aerated biofilm reactor[J]. WaterResearch, 2016, 94: 23-31.

[0012] Reference 2: Bunse P, Orschler L, Agrawal S, et al. Membrane aerated biofilm reactors for mainstream partial nitritation / anammox: experiences using realmunicipal wastewater[J]. Water Research X, 2020, 9: 100066. (Membrane aerated biofilm reactors for short-range nitrification-anaerobic ammonium oxidation of mainstream sewage: actual municipal wastewater treatment example).

[0013] Reference 3: Zhao B, Ma X, Xie F, et al. Development of simultaneous nitrification-denitrification and anammox and in-situ analysis of microbial structure in a novel plug-flow membrane-aerated sludge blanket[J]. Science of the Total Environment, 2021, 750(9): 142296. (Establishment of simultaneous nitrification-denitrification and anammox process in a novel plug-flow membrane aerated sludge blanket and in-situ analysis of microbial community structure).

[0014] Reference 4: Chen R, Zhou Y. Mainstream nitrogen removal in membrane aerated biofilm reactor at minimal lumen pressure[J]. Science of the Total Environment, 2022, 818:151758. (Mainstream nitrogen removal in membrane aerated biofilm reactor at minimal chamber pressure).

[0015] Reference 5: Li M, Li Y, Sun Z, et al. Partial nitrification / ANAMMOX (PN / A)membrane aerated biofilm reactor (MABR) under a low C / N ratio andmetagenomics identification[J]. Environmental Science-Water Research&Technology, 2022, 9(1): 265-273. (Short-cut nitrification / anaerobic ammonium oxidation (PN / A) membrane aerated biofilm reactor (MABR) under a low C / N ratio and metagenomics identification). Summary of the invention

[0016] In order to solve or alleviate at least one of the problems mentioned in the background art, the present application provides a series carrier-coupled membrane aeration biofilm reactor and a method for using the same.

[0017] The serial carrier-coupled membrane aeration biofilm reactor provided in the embodiment of the present application comprises at least two stages of membrane aeration biofilm reactor bodies arranged in series, wherein the membrane aeration biofilm reactor bodies comprise: a tank body, wherein the tank body comprises a water inlet and a water outlet, wherein the water outlet of the Nth stage of the membrane aeration biofilm reactor body is connected to the water inlet of the N+1th stage of the membrane aeration biofilm reactor body, wherein N≥1 and is an integer; a membrane assembly, comprising a plurality of hollow fiber membrane filaments; a coupling carrier, wherein anaerobic ammonia-oxidizing bacteria are enriched in the coupling carrier, wherein the coupling carrier is used to be arranged on the outside of the membrane assembly, and wherein the membrane assembly and the coupling carrier are arranged in the tank body.

[0018] In at least one embodiment, the hollow fiber membrane is formed into a rod shape, the axes of the plurality of hollow fiber membranes are parallel and arranged in a circular array, and the coupling carrier is arranged around the outside of the hollow fiber membrane.

[0019] In at least one embodiment, a plurality of coupling carriers formed as solid fillers are stacked between the cell body and the membrane assembly.

[0020] In at least one embodiment, the material of the hollow fiber membrane includes at least one of silica gel, polyethylene, polypropylene, and polyvinylidene fluoride.

[0021] In at least one embodiment, the coupling carrier has a shape of at least one of a granular shape, a porous block shape, a hollow cylinder shape, a wheel shape, and a brush shape.

[0022] In at least one embodiment, a temperature regulating device is provided at the cell body for controlling the temperature of the solution in the cell body.

[0023] The method for using the series carrier-coupled membrane aeration biofilm reactor provided in the present application uses the series carrier-coupled membrane aeration biofilm reactor as described above, and the method for using includes: performing short-range nitrification through the membrane assembly before adding the coupled carrier; and adding the coupled carrier on which anaerobic ammonia-oxidizing bacteria have completed biofilm formation.

[0024] In at least one embodiment, before adding the coupling carrier, the temperature of the solution in the cell body is controlled to be 30° C. to 35° C.

[0025] In at least one embodiment, before adding the coupling carrier, after nitrite accumulation occurs, the hydraulic retention time is gradually adjusted so that the effluent ammonia nitrogen concentration and nitrite concentration are between 1:0.8 and 1:1.2.

[0026] In at least one embodiment, the dosage of the coupling carrier is adjusted so that the nitrite concentration in the effluent is lower than 1 mg-N / L.

[0027] The present application constructs a device configuration that can achieve short-range nitrification-anaerobic ammonia oxidation denitrification based on a membrane aerated biofilm reactor. The coupled carrier solves the problems of low denitrification rate and poor effluent quality caused by the obstruction of ammonia nitrogen mass transfer in traditional membrane aerated biofilm reactors. At the same time, the series connection maintains the activity of NOB at a low level to achieve long-term stable and efficient denitrification.

[0028] The method of use provided in the present application applies the aforementioned device and also has the aforementioned advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic structural diagram of a series carrier-coupled membrane aeration biofilm reactor according to an embodiment of the present application is shown (taking a two-stage series connection as an example).

[0030] Figure 2 A schematic diagram of the biofilm structure and ammonia nitrogen concentration of a series carrier-coupled membrane aeration biofilm reactor and a traditional membrane aeration biofilm reactor according to an embodiment of the present application is shown.

[0031] Figure 3 The operating effect of the two-stage series carrier-coupled membrane aeration biofilm reactor according to the embodiment of the present application is shown.

[0032] Figure 4 The water quality and microbial activity of the inlet and outlet water of the single-stage carrier-coupled membrane aeration biofilm reactor in Comparative Example 1 at different hydraulic retention times are shown.

[0033] Figure 5 The denitrification rate and effluent quality of the single-stage carrier-coupled membrane aeration biofilm reactor in Comparative Example 1 at different hydraulic retention times are shown.

[0034] Figure 6 The water quality of the inlet and outlet water of the single-stage non-carrier coupled membrane aerated biofilm reactor according to Comparative Example 2 at different hydraulic retention times is shown.

[0035] Description of Reference Numerals

[0036] 100 membrane aeration biofilm reactor body; 110 first-stage membrane aeration biofilm reactor body; 120 second-stage membrane aeration biofilm reactor body;

[0037] 200 pool body; 210 water inlet; 220 water outlet; 230 return water outlet;

[0038] 300 membrane assembly; 310 hollow fiber membrane; 320 air inlet; 330 air outlet;

[0039] 400 coupling carrier;

[0040] 510 water inlet tank; 520 water inlet pump; 530 return pump;

[0041] 610 Inlet fan; 620 Valve DETAILED DESCRIPTION

[0042] The exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0043] like Figure 1 As shown, the serial carrier-coupled membrane aeration biofilm reactor (hereinafter, sometimes referred to as "membrane aeration biofilm reactor") provided by the present application may include at least two stages of membrane aeration biofilm reactor bodies 100 arranged in series. The membrane aeration biofilm reactor body 100 may include a tank body 200, a membrane assembly 300 and a coupling carrier 400.

[0044] The tank body 200 may include a water inlet 210 and a water outlet 220, and the water outlet 220 of the Nth-stage membrane aerated biofilm reactor body 100 is connected to the water inlet 210 of the N+1th-stage membrane aerated biofilm reactor body 100, where N≥1 and is an integer. For example, the water outlet 220 of the first-stage membrane aerated biofilm reactor body 110 is connected to the water inlet 210 of the second-stage membrane aerated biofilm reactor body 120.

[0045] The membrane assembly 300 may include a hollow fiber membrane filament 310. Anaerobic ammonia oxidizing bacteria are enriched in the coupling carrier 400 to form a carrier biofilm. The carrier biofilm is an anoxic or anaerobic biofilm. The coupling carrier 400 is disposed outside the membrane assembly 300. The membrane assembly 300 and the coupling carrier 400 are both disposed in the tank body 200.

[0046] like Figure 2 As shown in (a), the traditional membrane aeration biofilm reactor enriches anaerobic ammonia-oxidizing bacteria in the outer layer of the biofilm. The thickness of the anoxic zone in the outer layer of the biofilm is large, and the mass transfer resistance of ammonia nitrogen from the main solution to the aerobic zone in the inner layer of the biofilm is large, resulting in low ammonia nitrogen concentration in the aerobic zone, inhibited AOB activity, and low denitrification rate. In order not to inhibit AOB activity, it is necessary to maintain a very high ammonia nitrogen concentration in the main solution, which will deteriorate the effluent water quality. Figure 2 As shown in (b), the present application transfers the anaerobic ammonia-oxidizing bacteria from the membrane aeration biofilm to the biofilm of the coupling carrier 400 by additionally setting a coupling carrier 400, thereby reducing the thickness of the anaerobic layer at the membrane aeration biofilm and reducing the ammonia nitrogen mass transfer resistance. Therefore, under the condition that the effluent ammonia nitrogen concentration is lower than 5 mg-N / L, the present application can still maintain a relatively high ammonia nitrogen concentration in the aerobic zone of the biofilm, thereby maintaining a relatively high activity of AOB, solving the contradiction between the effluent ammonia nitrogen concentration and the denitrification rate, and achieving both the effluent ammonia nitrogen concentration meeting the standard and a relatively high denitrification rate.

[0047] There is a contradiction between the effluent ammonia nitrogen concentration and the total nitrogen removal rate in the traditional single-stage membrane aeration biofilm reactor: when the effluent ammonia nitrogen concentration is higher than the emission index, a relatively high total nitrogen removal rate can be maintained; when the effluent ammonia nitrogen concentration is lower than 5 mg-N / L, the AOB activity is limited, which may lead to the growth of NOB. NOB competes with anaerobic ammonia-oxidizing bacteria for nitrite to form nitrate, which reduces the total nitrogen removal rate and the effluent total nitrogen concentration cannot meet the standard. The present application adopts a multi-stage series structure to improve the distribution of ammonia nitrogen concentration. The first or first few stages of the membrane aeration biofilm reactor body 100 can remove most of the ammonia nitrogen and total nitrogen in the influent while maintaining NOB inhibition. Due to the high ammonia nitrogen concentration of the solution, the first few stages of the membrane aeration biofilm reactor body 100 can achieve stable NOB inhibition, and the denitrification rate is also higher. The last stage of the membrane aeration biofilm reactor can remove the remaining ammonia nitrogen and part of the total nitrogen, so that the effluent water quality meets the standard. The ammonia nitrogen concentration of the solution in the last stage of the membrane aeration biofilm reactor is lower than 5 mg-N / L, and NOB is easy to grow. However, since the total nitrogen concentration of the inlet water of the last stage of the membrane aeration biofilm reactor is already low, even if there is a certain amount of NOB, the total nitrogen concentration of the effluent water can meet the standard. The present invention solves the contradiction between the effluent ammonia nitrogen concentration and the total nitrogen removal rate by adopting a multi-stage series structure, and can ensure that the effluent ammonia nitrogen and total nitrogen concentrations meet the standards at the same time.

[0048] In one embodiment of the present application, Figure 1As shown, the tank body 200 may include a reflux outlet 230, which is used to pass the solution in the tank body 200 back into the water inlet 210, which is conducive to strengthening solution mixing and mass transfer. A temperature regulating device, such as a water bath layer, a heating belt, etc., may be provided at the tank body 200, for example, outside the tank body 200, to control the temperature of the solution in the tank body 200.

[0049] In one embodiment of the present application, the hollow fiber membrane filaments 310 are formed into a rod shape, and the membrane assembly 300 may include a plurality of hollow fiber membrane filaments 310 arranged in a circumferential array with parallel axes, so that the membrane assembly 300 is roughly formed into a column shape. It can be understood that the membrane assembly 300 in this arrangement is more concentrated than, for example, a line-up, and the coupling carrier 400 is more concentrated, and the nitrogen removal rate is high; the cell body volume is relatively small, and the arrangement is simpler.

[0050] The hollow fiber membrane 310 may be a dense hydrophobic material or a microporous hydrophobic material. For example, the dense hydrophobic material is a dense material that is air-permeable and water-impermeable, such as silica gel. The microporous hydrophobic material is a hydrophobic material with micropores, including polyethylene, polypropylene, polyvinylidene fluoride, etc. The micropore diameter may be 0.01-1.0 μm, allowing gas molecules such as oxygen to pass through, but not water to pass through.

[0051] The membrane assembly 300 can be located in the center of the tank body 200, and an air inlet 320 and an air outlet 330 are provided at both ends of the membrane assembly 300. Oxygen can be provided to the membrane assembly 300 through the air inlet 320, and then the membrane assembly 300 transfers the oxygen inside its membrane cavity to the outside, for example, sewage. Microorganisms in the sewage can attach to the surface of the hollow fiber membrane filaments 310 to form a membrane aeration biofilm. Figure 2 As shown in (b), in this embodiment, most of the microorganisms on the membrane aeration biofilm are aerobic microorganisms, among which the functional microorganisms are AOB (ammonia oxidizing bacteria), which can oxidize ammonia nitrogen into nitrite. In the outermost layer of the membrane aeration biofilm, the dissolved oxygen concentration is close to 0, and contains a small amount of anoxic or anaerobic microorganisms (such as anaerobic ammonia oxidizing bacteria, AnAOB), but the thickness of the anoxic or anaerobic layer is small.

[0052] In one embodiment of the present application, the main functional microorganisms on the surface of the coupling carrier 400 may be anaerobic ammonia-oxidizing bacteria, which can utilize nitrite to oxidize ammonia nitrogen to achieve the removal of total nitrogen.

[0053] The coupling carrier 400 can be a solid filler whose surface is easy for microorganisms to attach. The shape of the coupling carrier 400 is not fixed, for example, it can be granular, porous block, hollow cylinder, wheel, brush, etc. The material of the coupling carrier 400 is preferably soft, large specific surface area, and high bioaffinity, such as polyurethane sponge, polyolefin brush, etc. It can be understood that the soft material of the coupling carrier 400 can reduce damage to the aeration membrane, the large specific surface area can increase the amount of attached microorganisms, and the high bioaffinity can make the microorganisms attach faster and the amount of attachment is large.

[0054] In one embodiment of the present application, the membrane aerated biofilm reactor body 100 may include a water system. The water system may include an inlet tank 510, an inlet pump 520, a return pump 530, an inlet pipe, an outlet pipe, a return pipe, a valve and corresponding instruments, etc. Exemplarily, the two-stage membrane aerated biofilm reactor bodies 100 in series may be connected by a water tank and a water pump, or may be connected by an overflow pipe. For example, the water outlet 220 of the first-stage membrane aerated biofilm reactor body 110 is connected to the inlet tank 510, and the solution in the inlet tank 510 is pumped into the second-stage membrane aerated biofilm reactor body 120 by the inlet pump 520. Of course, the two-stage membrane aerated biofilm reactor bodies 100 may also be connected by an overflow pipe.

[0055] In one embodiment of the present application, the membrane aerated biofilm reactor body 100 may include an air intake system. The air intake system may include an air intake fan 610, an air intake pipe, an air outlet pipe, a valve 620, and corresponding instruments, etc. The air outlet pipe of the membrane assembly 300 may be opened and closed by the valve 620 to achieve the switching between the end-closed air supply and the end-open air supply.

[0056] The method for using the series carrier-coupled membrane aeration biofilm reactor body 100 provided in the present application may include the following steps.

[0057] (1) Start-up of short-range nitrification. Aerobic sludge from the biochemical pool of a domestic sewage treatment plant or domesticated short-range nitrification sludge is used as inoculated sludge. After inoculation, simulated sewage or actual domestic sewage is added and the system is operated intermittently for 1 to 2 days to complete biofilm formation. After biofilm formation is completed, the suspended sludge is discharged, and the membrane aerated biofilm reactor bodies of each level are operated in series 100 times and start to continuously inflow water to cultivate the membrane aerated biofilm. A relatively high circulation flow rate is controlled, or mechanical stirring is used to ensure that the reactor water is completely mixed and promote substrate mass transfer. A relatively low air supply pressure and air supply flow rate are controlled. It is recommended to use end-closed air supply to achieve the inhibition of NOB (nitrite oxidizing bacteria). It is recommended to control the solution temperature at 30°C to 35°C to promote the growth of AOB. A relatively short hydraulic retention time is used at the initial stage of startup to ensure that the effluent ammonia nitrogen concentration is not less than, for example, 20 mg-N / L. After the effluent ammonia nitrogen concentration stabilizes and nitrite accumulation occurs, the hydraulic retention time is gradually adjusted so that the effluent ammonia nitrogen concentration and nitrite concentration are between 1:0.8 and 1:1.2, for example, the effluent ammonia nitrogen concentration and nitrite concentration are close to 1:1.

[0058] (2) Adding coupling carrier 400 to achieve anaerobic ammonia oxidation denitrification. After the short-term nitrification is started, a certain amount of coupling carrier 400 that has completed the anaerobic ammonia oxidation bacteria biofilm in advance is added to the main solution of the membrane aerated biofilm reactor body 100. The amount of carrier added is based on the nitrite concentration in the effluent being lower than 1 mg-N / L. Gradually adjust the hydraulic retention time to make the effluent water quality meet the requirements. When the hydraulic retention time is too short, the concentrations of ammonia nitrogen and total nitrogen in the effluent cannot meet the requirements. When the hydraulic retention time is too long, there may be an oversupply of oxygen, causing NOB proliferation and bringing irreversible effects on the microbial community. Therefore, in long-term operation, excessive aeration must be guarded against. Other mixing, gas supply, and temperature conditions should be consistent with the short-term nitrification start-up stage. Among them, measures such as reducing the gas supply pressure and gas supply flow rate and reducing the circulation flow rate are helpful for NOB inhibition, but are not conducive to the removal of ammonia nitrogen, and can be applied as appropriate.

[0059] Furthermore, the present application also provides a specific embodiment and two comparative examples.

[0060] Example: Figure 1 The two-stage series carrier-coupled membrane aeration biofilm reactor shown.

[0061] The two-stage series carrier-coupled membrane aeration biofilm reactor for running a short-range nitrification-anaerobic ammonium oxidation process includes a tank body 200 formed by two organic glass cylinders. The effective volume of each stage of the membrane aeration biofilm reactor body 100 is about 0.98 L when the carrier is not filled. The membrane assembly 300 is a composite material of silica gel and non-woven fabric, and the total membrane area is 0.053 m 2 , the membrane area ratio is 54 m 2 / m 3The coupling carrier 400 is a cube carrier made of polyurethane sponge material, with an average side length of about 20 mm and a specific surface area of ​​more than 4000 m 2 / m 3 , the filling rate of the coupling carrier 400 is 30%. The sponge carrier completes the biofilm formation in the anaerobic ammonia oxidizing bacteria culture tank in advance.

[0062] Self-prepared simulated sewage was used as influent, and the influent ammonia nitrogen concentration was about 50 mg-N / L. After inoculating nitrification sludge, water was introduced into the two-stage membrane aeration biofilm reactor body 100, and the hydraulic retention time was 3 h (hours). The end open air supply was first used to accelerate the biofilm formation and growth of AOB and shorten the startup time; after AOB completed biofilm formation (the nitrite concentration of the effluent reached 5 mg-N / L or more), the end closed air supply was switched and maintained to achieve stable NOB inhibition. The closed air supply can be switched after the AOB has a sufficient number, but since the number of AOB cannot be measured in time, the timing of the switch can be based on the nitrite concentration of the effluent. After the short-range nitrification startup is achieved, a sponge carrier with anaerobic ammonia oxidizing bacteria biofilm is added, and the two-stage series operation is changed after the effluent is stable. The hydraulic retention time of the two-stage membrane aeration biofilm reactor body 100 is 3 h each, and the total retention time is 6 h. The internal circulation flow rate is 60 mL / min, and the water temperature is 30℃.

[0063] The inlet and outlet water effects and the AOB and NOB activities of the two-stage series carrier-coupled membrane aeration biofilm reactor body 100 are shown in FIG. Figure 3 As shown. Among them, Figure 3 (a) is the water quality of the inlet and outlet water of the first-stage membrane aeration biofilm reactor body 110; Figure 3 (b) is the AOB and NOB activities of the first-stage membrane aeration biofilm reactor body 110; Figure 3 (c) water quality of inlet and outlet water of the second-stage membrane aeration biofilm reactor body 120; Figure 3 (d) is the AOB and NOB activity of the second-stage membrane aeration biofilm reactor body 120. NH4 + -N represents ammonia nitrogen, NO2 - -N stands for nitrite, NO3 - -N stands for nitrate.

[0064] The device completed the short-range nitrification startup and anaerobic ammonium oxidation carrier addition on the 5th day, and achieved series operation on the 12th day.

[0065] like Figure 3 As shown in (a), the average effluent ammonia nitrogen concentration of the first-stage membrane aeration biofilm reactor body 110 is 20.0 mg-N / L, and the effluent total nitrogen concentration is 24.2 mg-N / L, which removes 52% of the total nitrogen in the influent, and the denitrification rate is 207 gN / (m3 ·d), which is at a relatively high level.

[0066] In terms of the stability of short-range nitrification, Figure 3 As shown in (b), the first-stage membrane aeration biofilm reactor body 110 achieved relatively stable NOB inhibition, and the NOB activity was basically maintained at 10 gN / (m 3 d) or below.

[0067] like Figure 3 (c) Figure 3 As shown in (d), the effluent ammonia nitrogen concentration of the second-stage membrane aeration biofilm reactor body 100 is lower than 2 mg-N / L, and the NOB activity reaches about 40 gN / (m 3 ·d). Since the total nitrogen concentration of the influent of the second-stage membrane aeration biofilm reactor 100 was only 24.2 mg-N / L, although the appearance of NOB affected the removal of total nitrogen, the final effluent total nitrogen concentration could still be stabilized at 9.4±2.4 mg-N / L. The overall total nitrogen removal rate of the two-stage series carrier-coupled membrane aeration biofilm reactor 100 reached 81%, and the denitrification rate reached 163 gN / (m 3 ·d) The effluent ammonia nitrogen concentration can be stabilized below 5 mg-N / L, and the total nitrogen concentration can be stabilized below 15 mg-N / L, meeting the Class A standard for urban sewage discharge.

[0068] Table 1 shows a comparison of the short-range nitrification-anaerobic ammonium oxidation process operating effects of the two-stage series carrier-coupled membrane aerated biofilm reactor and other traditional membrane aerated biofilm reactors with similar influent concentrations shown in the literature.

[0069] Table 1

[0070]

[0071] Among them, HRT is the hydraulic retention time.

[0072] It can be found that the present application has great advantages in terms of start-up time, hydraulic retention time, effluent ammonia nitrogen concentration, effluent total nitrogen concentration, denitrification rate, etc. It can be considered that the two-stage series carrier-coupled membrane aerated biofilm reactor achieves the optimization of the traditional membrane aerated biofilm reactor.

[0073] Comparative Example 1: Single-stage carrier-coupled membrane aeration biofilm reactor.

[0074] To verify the advantages of two-stage cascade operation, comparative example 1 uses a single-stage carrier-coupled membrane aeration biofilm reactor to operate a short-range nitrification-anaerobic ammonium oxidation process. The single-stage carrier-coupled membrane aeration biofilm reactor includes a tank body 200 formed by an organic glass cylinder, the effective volume of which is about 0.98 L when the carrier is not filled, and the membrane assembly 300 is a composite material of silica gel and non-woven fabric, with a total membrane area of ​​0.053 m 2 , the membrane area ratio is 54 m 2 / m 3 The carrier is a cube-shaped polyurethane sponge with an average side length of about 20 mm and a specific surface area of ​​>4000 m 2 / m 3 , the carrier filling rate is 30%. The sponge carrier completes biofilm formation in advance in the anaerobic ammonia oxidizing bacteria culture tank.

[0075] The start-up conditions of the single-stage carrier-coupled membrane aerated biofilm reactor are the same as those of the two-stage series carrier-coupled membrane aerated biofilm reactor. Self-prepared simulated sewage was used as the influent, and the influent ammonia nitrogen concentration was about 50 mg-N / L. After inoculation of nitrifying sludge, water was continuously inflowed at a hydraulic retention time of 3 h. The end open aeration was first used. After the AOB completed the biofilm formation, the end closed aeration was switched and maintained to achieve stable NOB inhibition. After the short-range nitrification was started, a sponge carrier with an anaerobic ammonia-oxidizing bacteria biofilm was added, and the hydraulic retention time was gradually extended from 3 h to 6 h to achieve the effluent water quality standard. The internal circulation flow rate was 60 mL / min and the water temperature was 30 °C.

[0076] The inlet and outlet water effects and the AOB and NOB activities of the single-stage carrier-coupled membrane aeration biofilm reactor body 100 at different hydraulic retention times are shown in FIG. Figure 4 As shown. Among them, Figure 4 (a) is the inlet and outlet water quality of the single-stage membrane aeration biofilm reactor; Figure 4 (b) shows the AOB and NOB activities of the single-stage membrane aeration biofilm reactor. Comparison of denitrification rate and effluent quality under different hydraulic retention times Figure 5 As shown. It can be found that with the extension of hydraulic retention time, the effluent ammonia nitrogen concentration of the single-stage carrier coupled membrane aeration biofilm reactor gradually decreased, and the effluent nitrate concentration increased slightly. In order to ensure that the effluent ammonia nitrogen and total nitrogen concentrations meet the standards, the retention time of the single-stage carrier coupled membrane aeration biofilm reactor needs to reach 6 h. Finally, when the hydraulic retention time reaches 6 h, the effluent ammonia nitrogen concentration drops to 0.73 mg-N / L, and the denitrification rate is still as high as 160 gN / (m 2 ·d), which was only reduced by 20% compared with the case of higher ammonia nitrogen concentration (3 h hydraulic retention time). This confirms the advantage of the carrier-coupled membrane aerated biofilm reactor, namely, optimizing ammonia nitrogen mass transfer and achieving high denitrification rates at low ammonia nitrogen concentrations.

[0077] However, if Figure 4 As shown in the figure, about 10 days after the hydraulic retention time reached 6 h, due to the low ammonia nitrogen concentration partially inhibiting the AOB activity, the single-stage carrier-coupled membrane aerated biofilm reactor began to show a gradual increase in NOB activity and a gradual decrease in total nitrogen removal rate (reflected in the increase in effluent ammonia nitrogen and nitrate concentrations). Finally, the NOB activity reached 60 gN / (m 3 ·d) above, the total nitrogen removal rate dropped to 43%, and both the effluent ammonia nitrogen and total nitrogen did not meet the standards. This confirmed that the single-stage carrier-coupled membrane aeration biofilm reactor could not maintain low NOB activity at low effluent ammonia nitrogen concentrations, so cascade operation was necessary.

[0078] Comparative Example 2: Single-stage non-carrier coupled membrane aeration biofilm reactor.

[0079] To verify the advantages of carrier-coupled operation, a single-stage non-carrier-coupled membrane aerated biofilm reactor operating a short-range nitrification-anaerobic ammonium oxidation process was compared. The effective volume of the device is about 1.2 m 3 The total membrane area is 40 m 2 , the membrane area ratio is 33 m 2 / m 3 Without adding coupling carrier 400, anaerobic ammonia-oxidizing bacteria grew in the outer layer of membrane aeration biofilm. The ammonia nitrogen concentration of the influent was 50~60mg-N / L.

[0080] The inlet and outlet water quality of the single-stage non-carrier coupled membrane aeration biofilm reactor at different hydraulic retention times is as follows Figure 6 As shown in the figure, as the hydraulic retention time gradually increased from 12 h to 24 h, the concentrations of ammonia nitrogen and total nitrogen in the effluent of the membrane aerated biofilm reactor gradually decreased. However, when the hydraulic retention time was further increased from 24 h to 29 h, the effluent ammonia nitrogen concentration of the non-carrier coupled membrane aerated biofilm reactor could not be further reduced, and the final effluent ammonia nitrogen concentration could only reach about 10 mg-N / L.

[0081] Due to the different membrane area ratios, the denitrification rates of Comparative Example 2 and Comparative Example 1 are not comparable. However, compared with the lowest effluent ammonia nitrogen concentration of less than 1 mg-N / L in Comparative Example 1, the effluent ammonia nitrogen concentration of Comparative Example 2 can only reach 10 mg-N / L. This shows that in the non-carrier coupled membrane aerated biofilm reactor of Comparative Example 2, when the solution ammonia nitrogen concentration reaches 10 mg-N / L, the AOB activity in the inner layer of the biofilm will be limited. The reason why AOB activity is limited is that a large number of anaerobic bacteria grow in the outer layer of the biofilm, and the overly thick anaerobic layer or anoxic layer hinders the mass transfer of ammonia nitrogen from the liquid phase to the inner layer of the biofilm, making the ammonia nitrogen concentration in the aerobic zone of the inner layer of the biofilm low, thereby inhibiting AOB activity. By observing the surface of the hollow fiber membrane filaments of Comparative Example 2, it can be found that the visible thickness of the membrane aeration biofilm reaches more than 1 mm, which confirms that the anaerobic layer of the biofilm is too thick. In contrast, the membrane aeration biofilms of the embodiment and comparative example 1 are brown and thin, and cannot be judged by naked eyes, while the anaerobic ammonia-oxidizing bacteria are mainly concentrated on the carrier biofilm.

[0082] In summary, the carrier-coupled membrane aerated biofilm reactor is beneficial to reducing the thickness of the membrane aerated biofilm, ensuring the activity of AOB, and reducing the effluent ammonia nitrogen concentration.

[0083] Other documents in Table 1 also use non-carrier coupled membrane aeration biofilm reactors, and the comparison in Table 1 can also prove the above conclusion.

[0084] The above is a preferred embodiment of the present application. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A series carrier-coupled membrane aeration biofilm reactor, characterized in that: The invention comprises at least two stages of membrane aeration biofilm reactor bodies (100) arranged in series, wherein the membrane aeration biofilm reactor body (100) comprises: A tank body (200), the tank body (200) comprising a water inlet (210) and a water outlet (220), the water outlet (220) of the membrane aerated biofilm reactor body (100) of the Nth stage being connected to the water inlet (210) of the membrane aerated biofilm reactor body (100) of the N+1th stage, N≥1 and being an integer; A membrane assembly (300) includes a plurality of hollow fiber membranes (310); A coupling carrier (400), anaerobic ammonia-oxidizing bacteria are enriched in the coupling carrier (400), the coupling carrier (400) is used to be arranged on the outside of the membrane assembly (300), the membrane assembly (300) and the coupling carrier (400) are arranged in the cell body (200), The hollow fiber membrane (310) is formed into a rod shape, the axes of the plurality of hollow fiber membranes (310) are parallel and arranged in a circular array, and the coupling carrier (400) is arranged around the outer side of the hollow fiber membrane (310). A plurality of coupling carriers (400) formed as solid fillers are stacked between the cell body (200) and the membrane assembly (300), and the shape of the coupling carriers (400) includes at least one of a granular shape, a porous block shape, a hollow cylinder, a wheel shape, and a brush shape.

2. The tandem carrier-coupled membrane aeration biofilm reactor according to claim 1, characterized in that: The material of the hollow fiber membrane (310) includes at least one of silica gel, polyethylene, polypropylene, and polyvinylidene fluoride.

3. The tandem carrier-coupled membrane aeration biofilm reactor according to claim 1, characterized in that: The cell body (200) is provided with a temperature regulating device for controlling the temperature of the solution in the cell body (200).

4. A method for using a series carrier-coupled membrane aeration biofilm reactor, characterized in that: The method of use uses the series carrier-coupled membrane aeration biofilm reactor according to any one of claims 1 to 3, and the method of use comprises: Before adding the coupling carrier (400), short-range nitrification is first performed through the membrane assembly (300) so that the ammonia nitrogen concentration of the effluent is not less than 20 mg-N / L; The coupling carrier (400) on which anaerobic ammonia-oxidizing bacteria have formed biofilm is added.

5. The method for using the series carrier-coupled membrane aeration biofilm reactor according to claim 4, characterized in that: Before adding the coupling carrier (400), the temperature of the solution in the cell body (200) is controlled to be 30° C. to 35° C.

6. The method for using the serial carrier-coupled membrane aeration biofilm reactor according to claim 4, characterized in that: Before adding the coupling carrier (400), after nitrite accumulation occurs, the hydraulic retention time is gradually adjusted so that the effluent ammonia nitrogen concentration and nitrite concentration are between 1:0.8 and 1:1.

2.

7. The method for using the series carrier-coupled membrane aeration biofilm reactor according to claim 4, characterized in that: The dosage of the coupling carrier (400) is adjusted so that the nitrite concentration in the effluent water is lower than 1 mg-N / L.

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