Domestic sewage treatment method and domestic sewage treatment system based on multi-bacteria cooperation

Abstract

The invention provides a domestic sewage treatment method and a domestic sewage treatment system based on multi-bacteria synergy, and relates to the technical field of domestic sewage treatment engineering design. The method comprises the following steps: an anaerobic reaction stage: hydrolyzing inert organic matters in domestic sewage through hydrolytic acidification bacteria to generate an easily degradable carbon source; the hydrolyzed easily-degradable carbon source is absorbed by denitrifying phosphorus-accumulating bacteria and denitrifying glycogen-accumulating bacteria and is stored in cells; an anoxic reaction stage: converting part of ammonia nitrogen and reflux nitrite into nitrogen through Anammox bacteria; an aerobic reaction stage: in the presence of hydroxylamine and in combination with intermittent high and low dissolved oxygen control, selectively oxidizing ammonia nitrogen into nitrite through Comamox bacteria; and a post-anoxic reaction stage: releasing generated nitrogen. According to the invention, the efficient cooperation of the hydrolytic acidification bacteria, the denitrifying phosphorus-accumulating bacteria, the denitrifying glycogen-accumulating bacteria, the Anammox bacteria and the Commox bacteria is utilized, so that the energy-saving low-carbon green sewage biological treatment is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of domestic sewage treatment engineering design, and in particular to a domestic sewage treatment method based on multi-microbial cooperation and a domestic sewage treatment system. BACKGROUND

[0002] In the field of sewage treatment, the traditional denitrification and phosphorus removal process is still the mainstream choice, but it has obvious limitations when treating high-pollution-load domestic sewage: the energy consumption of the aeration system accounts for a large proportion, the denitrification process indirectly increases carbon emissions, and the process modification space is limited, making it difficult to meet the development needs of green and low carbon.

[0003] The traditional denitrification path is through the nitrification and denitrification process: in the nitrification stage, ammonia nitrogen is oxidized to nitrate, which requires a large amount of aeration; in the denitrification stage, nitrate is reduced to nitrogen, which requires sufficient easily degradable carbon source. Due to the limited easily degradable carbon source in domestic sewage, the denitrification efficiency is low, and commercial carbon sources such as methanol often need to be added, increasing the operating cost and carbon footprint. At the same time, biological phosphorus removal relies on phosphorus-accumulating bacteria to absorb phosphorus, and the limitation of carbon source also affects its efficiency.

[0004] Short-cut nitrification combined with anaerobic ammonia oxidation is a new and efficient denitrification path. This path only oxidizes ammonia nitrogen to nitrite, which is then directly converted to nitrogen by anaerobic ammonia oxidation bacteria. Compared with the traditional path, it can save about 60% of the aeration energy consumption and 100% of the carbon source consumption. Achieving stable short-cut nitrification is the key to the successful operation of this process, which lies in promoting the enrichment of ammonia-oxidizing bacteria (AOB bacteria) and inhibiting nitrite-oxidizing bacteria (NOB bacteria).

[0005] Hydroxylamine is an effective way to achieve inhibition of nitrite-oxidizing microorganisms. Compared with commonly used free ammonia and free nitrite, it does not require additional chemical agents to regulate pH and does not require additional structures to clean residual free ammonia and free nitrite. However, the start-up time of hydroxylamine to achieve short-cut nitrification is relatively long, generally more than 5 days, and AOB bacteria are over-inhibited. SUMMARY

[0006] One of the purposes of the present application is to provide a domestic sewage treatment method based on multi-microbial cooperation to at least solve one of the technical problems existing in the prior art. The present application utilizes the efficient cooperation of hydrolytic acidification bacteria, denitrifying phosphorus-accumulating bacteria, denitrifying polysaccharide bacteria, Anammox bacteria and Comammox bacteria to achieve energy-saving, low-carbon and green sewage biological treatment.

[0007] The second purpose of the present application is to provide a domestic sewage treatment system.

[0008] In order to achieve the above-mentioned purposes of the present application, the following technical solutions are adopted: In a first aspect, the present application provides a domestic sewage treatment method based on multi-bacterial cooperation, comprising the following steps: (a) anaerobic reaction stage: hydrolysis of inert organic matter in domestic sewage by hydrolytic acidification bacteria to generate easily degradable carbon source, and denitrifying phosphorus accumulating bacteria and denitrifying glycogen accumulating bacteria absorb the easily degradable carbon source and store it in the cell; (b) anoxic reaction stage: the effluent of the anaerobic reaction stage is mixed with the nitrite produced in the aerobic reaction stage to form reflux liquid, which is introduced into the anoxic reaction stage, and part of the ammonia nitrogen in the influent is converted into nitrogen gas by Anammox bacteria, and phosphorus is absorbed and removed by denitrifying phosphorus accumulating bacteria; (c) aerobic reaction stage: the effluent of the anoxic reaction stage is introduced into the aerobic reaction stage, and the remaining ammonia nitrogen is selectively oxidized to nitrite by Comammox bacteria in the presence of hydroxylamine, and the nitrite is refluxed to the anoxic reaction stage; (d) post-anoxic reaction stage: the effluent of the aerobic reaction stage is introduced into the post-anoxic reaction stage, and the residual nitrate and nitrite are reduced to nitrogen gas by denitrifying glycogen accumulating bacteria using the intracellular stored carbon source.

[0009] Further, the hydraulic retention time of the anaerobic reaction stage of step (a) is 6-8 h; In the anaerobic reaction stage of step (a), the mixed liquor suspended solids concentration of the hydrolytic acidification reaction zone is controlled to be 4000-5000 mg / L.

[0010] Further, the hydraulic retention time of the anoxic reaction stage of step (b) is 2.5-3.5 h; In the anoxic reaction stage of step (b), the sludge age SRT of the system is controlled to be greater than or equal to 10 days.

[0011] Further, the hydraulic retention time of the aerobic reaction stage of step (c) is 2-3 h; In the aerobic reaction stage of step (c), intermittent aeration is used to control high and low dissolved oxygen concentrations, and the time ratio of the low dissolved oxygen period to the high dissolved oxygen period is 6:1-1:2, the low dissolved oxygen concentration range is less than 0.5 mg / L, and the high dissolved oxygen concentration range is 3-5 mg / L; In the aerobic reaction stage of step (c), the dosage concentration of hydroxylamine is 20-40 mg / L.

[0012] Further, the hydraulic retention time of the post-anoxic reaction stage of step (d) is 2-3 h; In the post-anoxic reaction stage of step (d), the mixed liquor suspended solids concentration is controlled to be 2000-4000 mg / L.

[0013] Further, fixed fillers are arranged in the anoxic reaction stage and / or the aerobic reaction stage, and the filler filling volume ratio is not less than 60%.

[0014] In a second aspect, as shown in the drawings, the present application provides a domestic sewage treatment system based on the domestic sewage treatment method based on the multi-bacterial cooperation, comprising an anaerobic stage reaction tank, an anoxic stage reaction tank, an aerobic stage reaction tank, and a post-anoxic stage reaction tank connected in sequence. Figure 1

[0015] Further, the domestic sewage treatment system further comprises a water inlet tank and a sedimentation tank. The water inlet tank is connected with the anaerobic stage reaction tank. The sedimentation tank is connected with the post-anoxic stage reaction tank.

[0016] Further, the aerobic stage reaction tank is further provided with a first reflux pump, the inlet end of the first reflux pump is connected with the aerobic stage reaction tank, and the outlet end of the first reflux pump is connected with the anoxic stage reaction tank.

[0017] Further, the sedimentation tank is connected with the anaerobic stage reaction tank through a second reflux pump.

[0018] Compared with the prior art, the present application has the following beneficial effects: The domestic sewage treatment method based on the multi-bacterial cooperation provided by the present application can convert inert organic matter into easily degradable carbon sources by hydrolysis acidification bacteria in the anaerobic stage, and the carbon sources are absorbed and stored as intracellular carbon sources by denitrifying phosphorus bacteria and denitrifying glycogen bacteria; in the anoxic stage, Anammox bacteria utilize nitrite and part of ammonia nitrogen for denitrification and at the same time reduce the alkalinity in the sewage, and the denitrifying phosphorus bacteria absorb phosphorus to remove phosphorus in the water; in the aerobic stage, hydroxylamine is added combined with intermittent high and low dissolved oxygen control, hydroxylamine can selectively inhibit the nitrite oxidation process of Comammox bacteria, realize the short-cut nitrification reaction dominated by Comammox bacteria, oxidize ammonia nitrogen into nitrite, and return the generated nitrite to the anoxic section; in the post-anoxic stage, the denitrifying glycogen bacteria utilize intracellular carbon sources to remove residual nitrate and nitrite, and realize deep denitrification. The present application utilizes the efficient cooperation of hydrolysis acidification bacteria, denitrifying phosphorus bacteria, denitrifying glycogen bacteria, Anammox bacteria and Comammox bacteria, and realizes energy-saving, low-carbon and green biological sewage treatment. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.​

[0020] Figure 1 The structural schematic diagram of the domestic sewage treatment system provided by the embodiment of the present application is shown.

[0021] Figure: 1 - water inlet tank; 2 - anaerobic stage reaction tank; 3 - anoxic stage reaction tank; 4 - aerobic stage reaction tank; 5 - post anoxic stage reaction tank; 6 - sedimentation tank; 21 - first water inlet pump; 22 - first stirring paddle; 31 - second stirring paddle; 32 - first reflux pump; 33 - first fixed filler; 34 - first sludge discharge port; 41 - aeration device; 42 - second fixed filler; 51 - third stirring paddle; 52 - water outlet; 61 - second reflux pump; 62 - second sludge discharge port. DETAILED DESCRIPTION

[0022] Unless otherwise defined, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by a person of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any latent ambiguity, the definitions provided herein take precedence over any dictionary or extrinsic definition. In this application, the use of "or" means "and / or" unless otherwise stated. Moreover, the use of the term "including" as well as other forms such as "include", "includes" for indicating the presence of one or more elements or components in a process, method, article, composition, formulation, mixture, or system is not limiting.

[0023] The technical solutions of the present application will be described clearly and completely in connection with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0024] The first aspect of the present application provides a domestic sewage treatment method based on multi-bacterial cooperation, comprising the following steps: (a) anaerobic reaction stage: hydrolysis of inert organic matter in domestic sewage by hydrolytic acidification bacteria to generate easily degradable carbon source, and denitrifying phosphorus accumulating bacteria and denitrifying glycogen accumulating bacteria absorb the easily degradable carbon source and store it in the cell; (b) anoxic reaction stage: mixing the effluent of the anaerobic reaction stage and the nitrite produced in the aerobic reaction stage into the anoxic reaction stage, converting part of the ammonia nitrogen in the influent (the ammonia nitrogen in the influent has two destinations, one is the utilization of part of the ammonia nitrogen by Anammox bacteria, and the other is the utilization of the remaining ammonia nitrogen in the influent by Comammox bacteria in the aerobic stage) into nitrogen gas with the refluxed nitrite, and simultaneously absorbing phosphorus by denitrifying phosphorus accumulating bacteria and removing phosphorus by sludge discharge; (c) aerobic reaction stage: transferring the effluent of the anoxic reaction stage into the aerobic reaction stage, and selectively oxidizing the remaining ammonia nitrogen into nitrite by Comammox bacteria in the presence of hydroxylamine, and the nitrite is refluxed to the anoxic reaction stage; (d) Post-denitrifying anoxic reaction stage: the effluent of the aerobic reaction stage is introduced into the post-denitrifying anoxic reaction stage, and the intracellularly stored carbon source of the denitrifying glycogen-accumulating organisms is used to reduce the residual nitrate and nitrite to generate nitrogen gas and release.

[0025] The present application couples the synergistic metabolic functions of hydrolytic acidification bacteria, denitrifying phosphorus-accumulating bacteria, denitrifying glycogen-accumulating bacteria, Comammox bacteria and Anammox bacteria to construct an efficient and energy-saving domestic sewage treatment method. In the anaerobic stage, the inert organic matter is hydrolyzed and converted into easily degradable carbon source and stored, in the anoxic stage, the anaerobic ammonia oxidation denitrification and denitrifying phosphorus removal are completed synchronously, in the aerobic stage, the hydroxylamine is used for regulation and combination with intermittent high and low dissolved oxygen regulation to realize stable short-cut nitrification dominated by Comammox bacteria, and the high energy consumption in the traditional full nitrification process is avoided; in the post-denitrifying anoxic stage, the intracellular carbon source is further used to drive deep denitrification to effectively remove the residual nitrogen. The overall process does not need to add commercial carbon source, significantly reduces the operation cost and carbon emission, simultaneously realizes efficient synergy of denitrification and phosphorus removal, and has the outstanding advantages of fast start-up, good stability and suitability for low carbon-nitrogen ratio sewage treatment.

[0026] In the present application, the Comammox bacteria can efficiently inhibit the nitrite oxidation step of the Comammox bacteria through the regulation of hydroxylamine and intermittent high and low dissolved oxygen. This is because hydroxylamine can selectively inhibit the nitrite oxidation step of Comammox bacteria. In addition, Comammox is adapted to grow and enrich in a low dissolved oxygen environment, while high dissolved oxygen is conducive to inhibiting the nitrite oxidation activity of Comammox. At the same time, high dissolved oxygen also helps to increase the ammonia oxidation activity of Comammox bacteria. In this way, the ammonia oxidation capacity can be ensured without inhibition, and the nitrite accumulation capacity of Comammox bacteria can be further promoted, and the denitrification efficiency can be improved by coupling with Anammox bacteria.

[0027] The denitrifying phosphorus-accumulating bacteria can simultaneously remove phosphorus and denitrify, realizing one carbon for two uses. The present application uses hydrolytic acidification bacteria to convert macromolecular carbon sources into small molecular carbon sources to ensure the efficiency of denitrifying phosphorus removal.

[0028] After denitrification in the traditional anaerobic ammonia oxidation process, nitrate often remains in the effluent, making it difficult to completely remove total nitrogen. In the present application, the denitrifying glycogen-accumulating bacteria use intracellularly stored carbon source for denitrification, which is placed in the subsequent process of anaerobic ammonia oxidation, which can effectively remove nitrite and nitrate in the effluent. Since this process does not require additional carbon source, theoretically, the total nitrogen concentration of the effluent can be reduced to near zero, achieving deep denitrification and significantly improving the nitrogen removal efficiency of the sewage treatment system.

[0029] The effects of the present application include: (1) Achieve efficient and stable short-cut nitrification control. Hydroxylamine (NH2OH) has the selective inhibition of the nitrite oxidation step of Comammox bacteria. By adding hydroxylamine (NH2OH) in the aerobic stage, short-cut nitrification dominated by Comammox bacteria is achieved. By combining low dissolved oxygen to enrich Comammox bacteria and high dissolved oxygen to inhibit the nitrite oxidation step of Comammox bacteria, the ammonia oxidation ability is not inhibited, and the nitrite accumulation ability of Comammox bacteria is further promoted, achieving stable and efficient short-cut denitrification in the aerobic stage.

[0030] (2) Significantly reduce energy consumption and carbon emissions. Through the synergistic effect of short-cut nitrification dominated by Comammox bacteria and anaerobic ammonia oxidation by Anammox bacteria, about 60% of aeration energy can be saved compared to traditional denitrification processes, and carbon source addition is completely avoided. At the same time, hydrolytic acidification bacteria convert the inert carbon source in domestic wastewater that is difficult to directly utilize into directly usable carbon source, and denitrifying phosphorus bacteria achieve "one carbon for two purposes", which reduces operating costs, explores available carbon sources in wastewater, and significantly reduces carbon footprint.

[0031] (3) Simultaneous efficient denitrification and phosphorus removal with increased treatment load. The present application ingeniously couples the metabolic pathways of four functional microorganisms to achieve integrated and synergistic treatment of "organic matter hydrolysis-short-cut nitrification-anaerobic ammonia oxidation-denitrifying phosphorus removal" in the same process, without the need for external organic carbon source for efficient denitrification and phosphorus removal.

[0032] (4) Achieve deep denitrification. Glycogen bacteria are used for internal carbon source denitrification to further remove residual nitrate and nitrite in the aerobic effluent, so that the total nitrogen in the effluent can theoretically be reduced to 0.

[0033] In some preferred embodiments, the hydraulic retention time of the anaerobic reaction stage of step (a) is 6-8 h, for example, it can be 6 h, 7 h, 8 h, etc. In the anaerobic reaction stage of step (a), the mixed liquor suspended solids concentration of the hydrolysis acidification reaction zone is controlled to be 4000-5000 mg / L, for example, it can be 4000 mg / L, 4500 mg / L, 5000 mg / L, etc.

[0034] In some preferred embodiments, the hydraulic retention time of the anoxic reaction stage of step (b) is 2.5-3.5 h, for example, it can be 2.5 h, 3 h, 3.5 h, etc. In the anoxic reaction stage of step (b), the sludge retention time SRT of the system is controlled to be greater than or equal to 10 days.

[0035] In some preferred embodiments, the hydraulic retention time of the aerobic reaction stage of step (c) is 2-3 h, for example, it can be 2 h, 2.5 h, 3 h, etc. In the aerobic reaction stage of step (c), the intermittent aeration mode is used to control the high and low dissolved oxygen concentrations, so that the time ratio of the low dissolved oxygen period to the high dissolved oxygen period is 6:1~1:2, the low dissolved oxygen concentration range is less than 0.5 mg / L, and the high dissolved oxygen concentration range is 3~5 mg / L. In the aerobic reaction stage of step (c), the hydroxylamine is added at a concentration of 20~40 mg / L, for example, it can be 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, etc.

[0036] In some preferred embodiments, the post-anoxic reaction stage of step (d) has a hydraulic retention time of 2~3h, for example, it can be 2h, 2.5h, 3h, etc. In the post-anoxic reaction stage of step (d), the mixed liquor suspended solids concentration is controlled to be 2000~4000 mg / L, for example, it can be 2000 mg / L, 3000 mg / L, 4000 mg / L, etc.

[0037] In some preferred embodiments, fixed fillers are provided in the anoxic reaction stage and / or the aerobic reaction stage, and the filler filling volume ratio is not less than 60%.

[0038] In the present application, in order to strengthen the retention of slow-growing Anammox bacteria, fillers are added in the anoxic stage to promote the formation of Anammox biofilm.

[0039] As shown in Figure 1 The second aspect of the present application provides a domestic sewage treatment system based on the domestic sewage treatment method based on the multi-bacterial cooperation, which comprises an anaerobic stage reaction tank 2, an anoxic stage reaction tank 3, an aerobic stage reaction tank 4, and a post-anoxic stage reaction tank 5 connected in sequence.

[0040] In some preferred embodiments, it further comprises a water inlet tank 1 and a sedimentation tank 6; the water inlet tank 1 is in communication with the anaerobic stage reaction tank 2; the sedimentation tank 6 is in communication with the post-anoxic stage reaction tank 5.

[0041] In some preferred embodiments, the aerobic stage reaction tank 4 is further provided with a first reflux pump 32, the inlet end of the first reflux pump 32 is in communication with the aerobic stage reaction tank 4, and the outlet end of the first reflux pump 32 is in communication with the anoxic stage reaction tank 3.

[0042] Optionally, the anaerobic stage reaction tank 2 is provided with a first stirring paddle 22.

[0043] Optionally, the anoxic stage reaction tank 3 is provided with a second stirring paddle 31, a first fixed filler 33, and a first sludge discharge port 34.

[0044] Optionally, the aerobic stage reaction tank 4 is equipped with an aeration device 41 and a second fixed packing material 42.

[0045] Optionally, the post-anoxic stage reaction tank 5 is equipped with a third stirring paddle 51 and a water outlet 52.

[0046] Optionally, the sedimentation tank 6 is equipped with a second reflux pump 61 and a second sludge discharge port 62.

[0047] Specifically, the inlet tank 1 is connected to the anaerobic stage reaction tank 2 via the first inlet pump 21; the anaerobic stage reaction tank 2 is connected to the anoxic stage reaction tank 3; the anoxic stage reaction tank 3 is connected to the aerobic stage reaction tank 4; the aerobic stage reaction tank 4 is connected to the post-anoxic stage reaction tank 5; the post-anoxic stage reaction tank 5 is connected to the sedimentation tank 6 via the outlet 52; and the sedimentation tank 6 is connected to the anaerobic stage reaction tank 2 via the second reflux pump 61.

[0048] In a preferred embodiment of the present invention, the method for treating domestic sewage based on multi-bacterial synergy includes the following steps: (1) Anaerobic reaction stage Domestic sewage first enters the anaerobic tank, where particulate matter and recalcitrant organic matter are converted into readily biodegradable carbon sources by hydrolytic acidifying bacteria.

[0049] Denitrifying polyphosphate bacteria and denitrifying polysaccharide bacteria rapidly absorb readily degradable carbon sources and store them intracellularly for subsequent denitrification of phosphorus and nitrogen. Simultaneously, denitrifying polyphosphate bacteria release PO4 into the liquid phase. 3- -P completes the two key reactions of "carbon capture" and "phosphorus release", providing sufficient electron donors for subsequent denitrification phosphorus uptake.

[0050] (2) Hypoxia response stage NO2 in effluent from anaerobic tank and return from aerobic tank - -N mixture enters the anoxic tank; (2-1) Anammox bacteria utilize part of the NH4 in the raw water + -N and reflux NO2 - -N undergoes anaerobic ammonia oxidation, directly converting nitrogen into N2.

[0051] (2-2) Denitrifying polyphosphate-accumulating bacteria use intracellular carbon sources as electron donors and NO2. - -N acts as an electron acceptor, simultaneously completing denitrification and phosphorus uptake, achieving "dual utilization of carbon," PO4 3- -P is removed as phosphorus-rich sludge through subsequent sludge discharge.

[0052] (3) Aerobic reaction stage (3-1) The effluent of the anoxic tank enters the aerobic tank, and hydroxylamine (NH2OH) is added as a selective inhibitor, which is added intermittently or continuously to inhibit the nitrite oxidation pathway of Comammox bacteria, prevent NO2 - from being further oxidized to NO3 - ; (3-2) Intermittent aeration is used to control low dissolved oxygen and high dissolved oxygen, and Comammox bacteria are enriched under low dissolved oxygen, and under the synergistic action of high dissolved oxygen and hydroxylamine, the ammonia oxidation process is dominated, most of NH4 + is oxidized to NO2 - , stable short-cut nitrification is realized, and NO2 - is stably accumulated. The concentration of NO2 - in the effluent is monitored, and the aerobic effluent rich in NO2 - is proportionally returned to the anoxic section to provide the substrate required for Anammox reaction.

[0053] (4) Post-anoxic section (4-1) The effluent of the aerobic section is introduced into the post-anoxic reaction tank, and the denitrifying glycocalyx bacteria use the internal carbon source stored in the anaerobic section to denitrify the remaining NO3 - -N and NO2 - -N to nitrogen, achieving a deep denitrification effect, and the total nitrogen removal rate is increased to more than 95%, and the total nitrogen concentration in the effluent is less than 5 mg / L.

[0054] (5) Biofilm enhanced retention The anoxic tank and the aerobic tank are filled with fixed fillers, and Anammox bacteria and Comammox bacteria form a dense biofilm on the surface of the fillers, which significantly reduces the risk of bacterial loss and ensures that the functional bacterial population is long-term stable and dominant.

[0055] Optionally, (6) sludge-water separation and phosphorus-rich sludge discharge: Part of the sludge in the sedimentation tank 6 is discharged from the system as excess sludge, and the other part is returned to the anaerobic zone to maintain the sludge concentration and activity in the anaerobic zone, and to ensure stable operation of the system.

[0056] Specifically, part of the settled sludge in the sedimentation tank 6 is returned to the anaerobic stage reaction tank 2 through the second return pump 61 to maintain the sludge concentration and activity in the anaerobic zone, and to ensure stable operation of the system; part of the settled sludge is discharged from the system as excess sludge through the second sludge discharge port 62 (discharge amount = 5-12% of the total sludge amount).

[0057] The application will be further described by examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0058] The influent water quality of the domestic sewage used in the following examples and comparative examples is as follows: Table 1, domestic sewage water quality

[0059] Example 1 The present embodiment provides a domestic sewage treatment method based on multi-bacterial cooperation, and the specific process is as follows: In the system starting stage, a functional bacterial community is established by using a partition inoculation method: Anaerobic activated sludge rich in hydrolytic acidification bacteria, denitrifying phosphorus bacteria and denitrifying polysaccharide bacteria is inoculated into the anaerobic stage reaction tank 2 (which can also be called a hydrolytic acidification reaction tank); Anammox bacteria-enriched sludge is inoculated into the anoxic stage reaction tank 3 to promote the formation of a biofilm on the surface of the filler; Nitrifying sludge containing Comammox bacteria is inoculated into the aerobic stage reaction tank 4 to construct a short-cut nitrification functional unit.

[0060] Then, sewage treatment operation is carried out: (1) Anaerobic reaction stage: The hydrolytic acidification bacteria and denitrifying phosphorus bacteria and denitrifying polysaccharide bacteria inoculated in the anaerobic sludge hydrolytic acidification tank are all floc bacteria, and the sludge concentration in the hydrolysis tank is maintained at 4500 mg / L.

[0061] Domestic sewage is first introduced into the anaerobic stage reaction tank 2 through the first water inlet pump 21, and the hydraulic retention time (HRT) = 6~8h.

[0062] (2) Anoxic reaction stage: The anoxic stage reaction tank 3 has been inoculated with Anammox bacteria and has grown into a biofilm. The effluent from the anaerobic tank is directly introduced into the anoxic stage reaction tank 3, and at the same time, the aerobic stage reaction tank 4 returns the accumulated NO2 - -N to the anoxic stage reaction tank 3 through the first reflux pump 32, and the reflux ratio R = 50~60%.

[0063] Among them, the sludge age SRT is controlled to be 10 days. The hydraulic retention time is 3 h.

[0064] (3) Aerobic reaction stage: After the effluent from the anoxic stage reaction tank 3 enters the aerobic stage reaction tank 4, the microporous aeration device 41 is used to intermittently control low dissolved oxygen (less than 0.5 mg / L) and high dissolved oxygen (3~5 mg / L) at a time ratio of 3:1. In this stage: hydroxylamine (NH2OH) is added as a selective inhibitor, and the addition concentration is 30 mg / L, which is continuously added. The hydraulic retention time is 2.5 h.

[0065] Among them, the aerobic effluent rich in NO2 - is returned to the anoxic stage reaction tank 3 to provide the substrate required for Anammox reaction.

[0066] (4) Post-hypoxia reaction stage: The effluent from the aerobic stage reaction tank 4 is introduced into the post-hypoxia stage reaction tank 5.

[0067] The MLSS is maintained at 2000-4000 mg / L, and the hydraulic retention time is 2.5 h.

[0068] In addition, the anoxic stage reaction tank 3 and the aerobic stage reaction tank 4 are filled with three-dimensional elastic fillers, and the filling rate is ≥60%. The Anammox bacteria and Comammox bacteria form a dense biofilm on the surface of the fillers, and the biofilm thickness is 1-2 mm.

[0069] At the same time, part of the settled sludge in the sedimentation tank 6 is returned to the anaerobic stage reaction tank 2 through the second return pump 61 to maintain the sludge concentration and activity in the anaerobic zone and ensure stable operation of the system; part of the settled sludge is discharged from the system as excess sludge through the second sludge discharge port 62 (discharge amount = 5-12% of the total sludge amount).

[0070] Example 2 The present embodiment provides a domestic sewage treatment method based on multi-bacterial cooperation, which differs from Example 1 in that the hydroxylamine dosage concentration is 20 mg / L.

[0071] Example 3 The present embodiment provides a domestic sewage treatment method based on multi-bacterial cooperation, which differs from Example 1 in that the hydroxylamine dosage concentration is 40 mg / L.

[0072] Example 4 The present embodiment provides a domestic sewage treatment method based on multi-bacterial cooperation, which differs from Example 1 in that the hydroxylamine dosage concentration is 15 mg / L.

[0073] Example 5 The present embodiment provides a domestic sewage treatment method based on multi-bacterial cooperation, which differs from Example 1 in that the hydroxylamine dosage concentration is 45 mg / L.

[0074] Example 6 The present embodiment provides a domestic sewage treatment method based on multi-bacterial cooperation, which differs from Example 1 in that the hydraulic retention time is: 6 h for the anaerobic reaction stage, 2.5 h for the anoxic reaction stage, 2 h for the aerobic reaction stage, and 2 h for the post-hypoxia reaction stage.

[0075] Example 7 The present embodiment provides a domestic sewage treatment method based on multi-bacterial cooperation, which differs from Example 1 in that the hydraulic retention time is: 8 h for the anaerobic reaction stage, 3.5 h for the anoxic reaction stage, 3 h for the aerobic reaction stage, and 3 h for the post-hypoxia reaction stage.

[0076] Example 8 The present example provides a domestic sewage treatment method based on multi-bacterial cooperation, which is different from Example 1 in that no fixed filler is arranged in the reaction tank 3 in the anoxic stage and the reaction tank 4 in the aerobic stage.

[0077] Comparative Example 1 The present comparative example provides a domestic sewage treatment method, which is different from Example 1 in that no hydroxylamine is added.

[0078] Comparative Example 2 The present comparative example provides a domestic sewage treatment method, which is different from Example 1 in that only hydroxylamine is added, no intermittent dissolved oxygen control is performed, and the same concentration of hydroxylamine as in Example 1 is added.

[0079] Comparative Example 3 The present comparative example provides a domestic sewage treatment method, which is different from Example 1 in that no hydrolytic acidification bacteria are contained in the anaerobic reaction stage.

[0080] Test Example Test method: Take the mixed sludge of the anaerobic tank, the anoxic tank, the aerobic tank and the post-anoxic tank, filter, and use the supernatant to detect total nitrogen (HJ 636-2012 Alkaline potassium persulfate digestion ultraviolet spectrophotometric method), COD (HJ 828-2017 Potassium dichromate method) and total phosphorus (GB 11893-89 Ammonium molybdate spectrophotometric method).

[0081] The test results are shown in Table 2.

[0082] Table 2

[0083] From the data in Table 2, it can be seen that after the domestic sewage is treated by the device and method, the total nitrogen in the effluent is <5 mg / L, the COD is <50 mg / L, and the PO4 3- -P <0.2 mg / L. Specifically, Example 1 shows a more comprehensive treatment performance. In contrast, Examples 2-3- and 6-7, although slightly fluctuating (total nitrogen rising to 4.3-4.9 mg / L), are still stable and superior to the 5 mg / L limit, verifying the reliability of the preferred parameter range in the present solution; while Examples 4-5 total nitrogen rises to 5.7-6.7 mg / L, COD and phosphorus rise synchronously, indicating that the hydroxylamine concentration is too low to inhibit Comammox nitrite oxidation, and too high may non-specifically inhibit ammonia oxidation activity; Example 8 (without filler) total nitrogen reaches 8.4 mg / L, significantly inferior to the filler group; Comparative Example 1 without hydroxylamine, Comparative Example 3 without hydrolytic acidification bacteria, both with total nitrogen ≥7.6 mg / L, proving the necessity of in-situ conversion of hydroxylamine and inert carbon source.

[0084] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for treating domestic sewage based on multi-bacterial synergy, characterized in that, Includes the following steps: (a) Anaerobic reaction stage: Inert organic matter in domestic sewage is hydrolyzed by hydrolytic acidifying bacteria to generate easily degradable carbon sources. Denitrifying polyphosphate bacteria and denitrifying polysaccharide bacteria absorb the easily degradable carbon sources and store them in their cells. (b) Anoxic reaction stage: The effluent from the anaerobic reaction stage is mixed with the nitrite reflux liquid produced in the aerobic reaction stage and then enters the anoxic reaction stage. Anammox bacteria convert part of the ammonia nitrogen in the influent and the reflux nitrite into nitrogen gas. At the same time, denitrifying polyphosphate bacteria absorb phosphorus and remove phosphorus by discharging sludge. (c) Aerobic reaction stage: The effluent from the anoxic reaction stage is transferred to the aerobic reaction stage. In the presence of hydroxylamine, the remaining ammonia nitrogen is selectively oxidized to nitrite by Commammox bacteria, and the nitrite is returned to the anoxic reaction stage. (d) Post-anoxic reaction stage: The effluent from the aerobic reaction stage is introduced into the post-anoxic reaction stage, where denitrifying polysaccharide bacteria use the carbon source stored in their cells to reduce the residual nitrates and nitrites, generating nitrogen gas for release.

2. The method for treating domestic sewage based on multi-bacterial synergy according to claim 1, characterized in that, The hydraulic retention time for the anaerobic reaction stage in step (a) is 6-8 h; In the anaerobic reaction stage of step (a), the concentration of suspended solids in the mixed liquor of the hydrolysis and acidification reaction zone is controlled to be 4000–5000 mg / L.

3. The method for treating domestic sewage based on multi-bacterial synergy according to claim 1, characterized in that, The hydraulic retention time in the anoxic reaction stage of step (b) is 2.5~3.5 h; In the anoxic reaction stage of step (b), the sludge age SRT of the control system is greater than or equal to 10 days.

4. The method for treating domestic sewage based on multi-bacterial synergy according to claim 1, characterized in that, The hydraulic retention time for the aerobic reaction stage in step (c) is 2-3 hours. In the aerobic reaction stage of step (c), intermittent aeration is used to control the high and low dissolved oxygen concentrations, so that the time ratio of the low dissolved oxygen period to the high dissolved oxygen period is 6:1 to 1:2, the low dissolved oxygen concentration range is less than 0.5 mg / L, and the high dissolved oxygen concentration range is 3 to 5 mg / L. In the aerobic reaction stage of step (c), the concentration of hydroxylamine added is 20–40 mg / L.

5. The method for treating domestic sewage based on multi-bacterial synergy according to claim 1, characterized in that, The hydraulic retention time in the post-anoxic reaction stage of step (d) is 2-3 h; In the post-anaerobic reaction stage of step (d), the concentration of suspended solids in the mixed solution is controlled at 2000~4000 mg / L.

6. The method for treating domestic sewage based on multi-bacterial synergy according to claim 1, characterized in that, In the hypoxic reaction stage and / or the aerobic reaction stage, a fixed packing material is provided, and the packing volume ratio is not less than 60%.

7. A domestic sewage treatment system based on the multi-bacterial synergistic domestic sewage treatment method according to any one of claims 1-6, characterized in that, It includes an anaerobic stage reactor, an anoxic stage reactor, an aerobic stage reactor, and a post-anoxic stage reactor that are connected in sequence.

8. The domestic sewage treatment system according to claim 7, characterized in that, It also includes an inlet tank and a sedimentation tank; The inlet tank is connected to the anaerobic stage reaction tank; The sedimentation tank is connected to the post-anoxic stage reaction tank.

9. The domestic sewage treatment system according to claim 7, characterized in that, The aerobic stage reaction tank is also equipped with a first reflux pump, the inlet end of which is connected to the aerobic stage reaction tank, and the outlet end of which is connected to the anoxic stage reaction tank.

10. The domestic sewage treatment system according to claim 8, characterized in that, The sedimentation tank and the anaerobic stage reaction tank are connected by a second reflux pump.

Images