Sewage treatment method for promoting MBBR filler biofilm formation

Abstract

The invention discloses a method for promoting MBBR filler biofilm formation, and belongs to the technical field of sewage treatment. The invention provides a method for promoting MBBR (Moving Bed Biofilm Reactor) filler biofilm formation, which utilizes microbial signal transmission and a microbial quorum sensing (QS) mechanism to realize rapid and massive colonization of microorganisms and increase of the thickness of a biofilm, and effectively reduces the ammonia nitrogen content in sewage at the same time. According to the present invention, the rural domestic sewage is treated by using the pure membrane operation reactor, such that the COD removal rate can achieve more than 98.6%, the ammonia nitrogen removal rate can achieve more than 93.2%, and the total nitrogen removal rate can achieve more than 78.1%.

Description

Technical Field

[0001] The present invention relates to a sewage treatment method for promoting the biofilm formation on MBBR fillers, belonging to the technical field of sewage treatment. Background Art

[0002] With the development of the economy and the improvement of the quality of life, there has been a substantial increase in domestic wastewater, industrial wastewater, and agricultural non-point source pollution. The nitrogen substances rich in these polluted wastewaters are continuously discharged into water bodies, resulting in serious eutrophication problems in waters such as rivers and lakes. This situation not only leads to a significant degradation of the ecological system but also greatly reduces the ecological service function.

[0003] Therefore, the development of efficient and low-cost sewage treatment technologies, especially for the deep removal of ammonia nitrogen and total nitrogen, has become an urgent need in the current environmental protection field. Existing sewage treatment methods, such as oxidation ditches and SBRs, can remove pollutants in sewage to a certain extent, but they have limitations in terms of treatment efficiency, operating cost, and operation complexity. Especially when treating sewage with high concentrations of ammonia nitrogen and total nitrogen, it often requires a long treatment cycle and high energy consumption, and the treatment effect is unstable, making it difficult to meet the increasingly strict environmental protection discharge standards.

[0004] In the prior art, the Chinese patent application text with the publication number CN116813081A discloses the use of an SBR reactor, inoculating activated sludge that has been placed anoxically for one month, with MLSS = 2700 - 3300 mg / L; the influent time is 5 min, the reaction time is 35 - 90 min, the sedimentation time is 30 min, and the drainage time is 5 min; continuous stirring is carried out throughout the reaction cycle; during the reaction process, the hydraulic retention time (HRT) is continuously shortened according to the change in the effluent nitrite concentration; the drainage ratio is 50%, HRT = 70 - 180 min, C6-HSL is added externally to the simulated wastewater, and the concentration of C6-HSL after being added to the reactor is 20 - 35 mg / g-VSS, and it operates 1 - 2 cycles per day; in the first half month, in order to stabilize the water quality, simulated sewage is used instead of actual sewage, and then it starts to treat actual sewage containing nitrite. This prior art mainly treats common urban domestic sewage and does not treat rural domestic sewage. Rural domestic sewage has significant differences from urban domestic sewage in terms of water volume, composition, concentration, treatment conditions, etc., showing characteristics such as higher pollutant concentration and large water quality fluctuations.

[0005] The Chinese patent application text with the publication number CN109019860A discloses a device and method for treating municipal wastewater by a simultaneous nitrification and denitrification membrane-biofilm reactor. In the method, the volume ratio of the sponge filler added is 30%-50%, the aeration volume in the startup stage is set to 0.8-1.2 L / min, the hydraulic retention time is 24 h for 1-10 days, 18 h for 11-20 days, and 12 h after 21 days, and the suspended sludge adheres to the carrier to form a biofilm. In the stable stage, the aeration volume is changed from 0.8-1.2 L / min to 0.3-0.6 L / min. This prior art mainly treats common municipal wastewater and does not treat rural domestic sewage. However, there are significant differences between rural domestic sewage and urban domestic sewage in terms of water volume, composition, concentration, treatment conditions, etc., showing characteristics such as higher pollutant concentration and large water quality fluctuations.

[0006] The Chinese patent text with the publication number CN110540292B discloses an enhanced simultaneous nitrification and denitrification process of adding AHLs signal molecules to a biological moving bed process. For the biological moving bed process, including the biofilm formation process and the operation process in the moving bed biofilm process and the composite process of biofilm and activated sludge, AHLs signal molecules (mixtures such as C4, C8, C14, etc.) are added to promote quorum sensing QS, which is crucial for the formation of bacterial biofilms. This technology has the problem of poor total nitrogen removal effect.

[0007] In a moving bed biofilm reactor (MBBR), the biofilm formation on the filler is one of the key technologies determining the reactor operation performance. The formation process of the biofilm usually includes the processes of microbial attachment, colonization, reproduction, and metabolism. The microbial attachment on the filler surface is a bottleneck during the startup of the reactor. The traditional biofilm formation process has problems such as slow microbial colonization rate and low biofilm formation efficiency. Since microorganisms need a certain amount of time to adapt to the environment and form a stable biofilm, the traditional method often requires a long startup period to achieve good sewage treatment effects, which not only prolongs the startup time but also reduces the overall treatment efficiency of the reactor. Especially during high-load or sudden pollution events, it is easy to cause unstable reactor performance and even lead to system failures. In the prior art, most of the biofilm formation methods for MBBR fillers adopt the natural biofilm formation method, but this method has a slow biofilm formation speed, and it is difficult to guarantee the thickness and quality of the biofilm.

[0008] In summary, how to effectively reduce the ammonia nitrogen content is also an urgent problem to be solved in the field of sewage treatment. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, the present invention proposes a sewage treatment method for promoting the biofilm formation on MBBR fillers. This method utilizes microbial signal transduction and the microbial quorum sensing mechanism (QS), achieving rapid and massive colonization of microorganisms and an increase in the thickness of the biofilm, while effectively reducing the ammonia nitrogen content in the sewage.

[0010] Signal transduction among microorganisms, especially the quorum sensing mechanism, plays a crucial role in microbial colonization, regulation of group behavior, and biofilm formation. Quorum sensing signal molecules refer to some low-molecular compounds secreted by microorganisms. These signal molecules can transmit information among microbial populations. When the concentration of signal molecules in the population reaches a certain threshold, the microorganisms respond collectively, showing coordinated behaviors, including population proliferation, metabolite transformation, enhanced drug resistance, and biofilm formation, etc.

[0011] During the sewage treatment process, by regulating the concentration of quorum sensing signal molecules, the rapid attachment of microorganisms and the rapid formation of biofilms can be effectively promoted. Compared with traditional methods, signal molecules have a more efficient role in regulating the behavior of microbial populations, which can significantly shorten the biofilm formation time and improve the colonization rate of microorganisms on the filler surface. Utilizing signal molecules, especially quorum sensing signal molecules, can prompt microorganisms to complete the colonization of the film and the formation of a thick film within a short time, greatly shortening the start-up period of the biofilm reactor and effectively improving the treatment efficiency of the reactor.

[0012] The first object of the present invention is to provide a method for promoting the biofilm formation on fillers, and the method includes:

[0013] Inoculate the activated sludge from the aerobic tank into the reactor and add MBBR suspended fillers; add sewage to the reactor, and add the signal molecule C6-HSL during the reaction. After operating the reactor for four weeks, the biofilm-covered fillers are obtained;

[0014] Among them, operating the reactor includes inlet water, aeration and agitation, sedimentation, outlet water, and stagnation;

[0015] In the first week, maintain the activated sludge concentration at 2800 - 3500 mg / L and add 1 - 10 nmol / L of the signal molecule C6-HSL;

[0016] In the second week, maintain the activated sludge concentration at 1500 - 2500 mg / L and add 20 - 40 nmol / L of the signal molecule C6-HSL;

[0017] In the third week, maintain the activated sludge concentration at 500 - 1500 mg / L and add 40 - 60 nmol / L of the signal molecule C6-HSL;

[0018] In the fourth week, the concentration of activated sludge was maintained at 0 mg / L, and the signal molecule C6-HSL was added at a concentration of 90-110 nmol / L.

[0019] In one embodiment, the reactor is an SBR reactor.

[0020] In one embodiment, the working volume of the SBR reactor is 4 L, and the drainage ratio is 1 / 4.

[0021] In one embodiment, the MBBR suspended packing is K3 packing.

[0022] In one embodiment, MBBR suspended packing is added to the SBR reactor, and the dosage of the packing is 20%-50% (v / v) of the effective volume of the reactor; activated sludge is inoculated into the SBR reactor, and the inoculation amount of the activated sludge is MLSS = 2800-3500 mg / L of the effective volume of the reactor; the total hydraulic retention time (HRT) of the SBR reactor is 5-10 h, including the stages of influent, aeration and agitation, sedimentation, effluent, and stagnation; signal molecule C6-HSL is added to the influent at a concentration of 10-100 nmol / L, and the biofilm formation time of the SBR reactor is divided into four stages. With time, the dosage of C6-HSL is gradually increased, and the sludge concentration is gradually reduced by sludge discharge, and finally a sewage treatment system operating with pure biofilm is obtained.

[0023] In one embodiment, the sewage is rural domestic sewage, and its components include 100-300 mg / L COD, 20-100 mg / L NH4 + -N, 1-20 mg / L PO4 3- -P, 1-20 TP mg / L, 20-150 mg / L TN, 0-20 mg / L NO3 - -N, 0-10 mg / L NO2 - -N.

[0024] In one embodiment, when operating the reactor, the influent time is 5-10 min; the aeration and agitation time is 280-350 min; the sedimentation time is 25-60 min; the effluent time is 5-10 min; the stagnation stage time is 15-30 min.

[0025] In one embodiment, the pH is maintained at 6.5-7.5 when operating the reactor.

[0026] In one embodiment, the inoculation amount of activated sludge in the aerobic tank is MLSS of 2800-3500 mg / L;

[0027] Optionally, the inoculation amount of activated sludge in the aerobic tank is MLSS of 3000 mg / L.

[0028] In one embodiment, the addition amount of the MBBR suspended packing is 20%-50% v / v;

[0029] Optionally, the addition amount of the MBBR suspended packing is 30% v / v.

[0030] The second object of the present invention is to provide a method for simultaneously improving the removal rates of COD, ammonia nitrogen and total nitrogen in sewage, using a reactor operating with a pure membrane to treat sewage; the preparation method of the reactor operating with a pure membrane is as follows:

[0031] Inoculate the aerobic tank activated sludge into the reactor and add the MBBR suspended packing; add sewage to the reactor, add the signaling molecule C6-HSL during the reaction period, and obtain the reactor operating with a pure membrane after operating the reactor for four weeks;

[0032] Among them, operating the reactor includes inlet water, aeration and stirring, sedimentation, outlet water, and stagnation;

[0033] In the first week, maintain the activated sludge concentration at 2800-3500 mg / L and add 0-10 nmol / L of the signaling molecule C6-HSL;

[0034] In the second week, maintain the activated sludge concentration at 1500-2500 mg / L and add 20-40 nmol / L of the signaling molecule C6-HSL;

[0035] In the third week, maintain the activated sludge concentration at 500-1500 mg / L and add 40-60 nmol / L of the signaling molecule C6-HSL;

[0036] In the fourth week, maintain the activated sludge concentration at 0 mg / L and add 90-110 nmol / L of the signaling molecule C6-HSL.

[0037] In one embodiment, the sewage is rural domestic sewage, and its components include 100-300 mg / L COD, 20-100 mg / L NH4 + -N, 1-20 mg / L PO4 3- -P, 1-20 TP mg / L, 20-150 mg / L TN, 0-20 mg / L NO3 - -N, 0-10 mg / L NO2 - -N.

[0038] In one embodiment, when operating the reactor, the inlet water time is 5-10 min; the aeration and stirring time is 280-350 min; the sedimentation time is 25-60 min; the outlet water time is 5-10 min; the stagnation stage time is 15-30 min.

[0039] In one embodiment, the inoculation amount of activated sludge in the aerobic tank, MLSS, is 2,800 - 3,500 mg / L;

[0040] Optionally, the inoculation amount of activated sludge in the aerobic tank, MLSS, is 3,000 mg / L;

[0041] The addition amount of MBBR suspended packing is 20% - 50% v / v;

[0042] Optionally, the addition amount of MBBR suspended packing is 30% v / v.

[0043] The third object of the present invention is to provide the application of any of the above - mentioned methods in sewage treatment.

[0044] Advantages of the present invention

[0045] Rural domestic sewage refers to the wastewater generated in the daily life of rural residents, mainly from activities such as household life, sanitation facilities, kitchens, washing, and breeding. Compared with urban domestic sewage, rural domestic sewage has some significant characteristics, which need to be particularly considered in the process of pollution control and water treatment. The following are the main characteristics of rural domestic sewage: small and fluctuating water volume, diverse pollutant components, relatively high pollutant concentration, dispersion and non - uniformity, and complex water quality pollution sources. This makes the treatment of rural sewage face many challenges, and it is necessary to adopt local treatment schemes, such as establishing small - scale decentralized sewage treatment facilities, promoting ecological treatment technologies, and strengthening rural sewage management, to ensure that the sewage is effectively treated and the environmental pollution is reduced.

[0046] The present invention provides a method for promoting biofilm formation on MBBR packing. This method utilizes microbial signal transduction and the microbial quorum sensing mechanism (QS), achieving rapid and large - scale colonization of microorganisms and an increase in the thickness of the biofilm, while effectively reducing the ammonia nitrogen content in the sewage. Specifically:

[0047] The present invention uses a reactor with pure membrane operation to treat rural domestic sewage, with a COD removal rate of over 98.6%, an ammonia nitrogen removal rate of over 93.2%, and a total nitrogen removal rate of over 78.1%. Description of the drawings

[0048] Figure 1It is a comparison diagram of the biofilm effect; among them, the left picture is the effect of Example 1, the biofilm is uniform and stable: the surface of the filler can be evenly attached with a stable biofilm, and the thickness of the film is moderate, which is conducive to the growth and reproduction of microorganisms. Strong biofilm adhesion: the surface of the filler shows strong hydrophilicity or hydrophobicity, which can effectively adsorb microorganisms, so that the biofilm can be firmly attached and not easy to fall off. High biofilm activity: the microbial community after biofilming is highly active, and a stable ecosystem can be formed on the surface of the filler to promote the degradation and transformation of organic matter. The right picture is the effect of comparative example 3, the biofilm is uneven: the biofilm on the surface of the filler is very thin and unevenly covered, resulting in insufficient biodegradation ability. Poor adhesion: the hydrophilicity or hydrophobicity of the filler surface is not suitable, which makes it difficult for microorganisms to attach. Unstable biofilm: the biofilm after biofilming is easily affected by changes in the external environment, such as fluctuations in temperature, pH value, etc., resulting in unstable or destroyed film layers. Low biofilm activity: after the biofilm is formed, the activity of the microbial community is low, and it is impossible to effectively degrade or treat organic matter. DETAILED DESCRIPTION

[0049] 1. Raw materials involved in the following examples and comparative examples:

[0050] K3 filler was purchased from Sipurun Technology Co., Ltd.;

[0051] The signal molecule C6-HSL was purchased from Aladdin;

[0052] Aerobic tank sludge comes from Yixing Concept Plant.

[0053] 2. Composition of activated sludge in aerobic pool:

[0054] Aerobic bacteria

[0055] Aerobic bacteria degrade organic and inorganic matter by oxidation in an aerobic environment. They usually use organic matter as a carbon source and oxygen as an electron acceptor to perform aerobic respiration, playing a core role in removing pollutants.

[0056] Main types:

[0057] Heterotrophic Bacteria: This type of bacteria uses organic matter as a carbon source, uses oxygen for respiration, and degrades organic pollutants in the water. It is the main force in degrading organic matter in aerobic pools, and can decompose carbon sources in water (such as COD, BOD) into carbon dioxide and water, reducing organic pollutants in the water.

[0058] Autotrophic bacteria: use inorganic substances (such as ammonia nitrogen and nitrate) as carbon sources and carry out redox reactions. The most common are nitrifying bacteria, which participate in the nitrogen cycle.

[0059] Nitrifying bacteria: such as Nitrosomonas and Nitrobacter. Nitrifying bacteria convert ammonia nitrogen (NH3) into nitrite (NO2 - ), and then further convert it into nitrate (NO3 - ). It participates in nitrogen removal, and nitrification is an important way to remove ammonia nitrogen in sewage.

[0060] Denitrifying bacteria: such as Pseudomonas and Bacillus, etc., are bacteria that can reduce nitrate (NO3 - ) to nitrogen gas (N2) under anoxic conditions, and are usually active in the transition area between the aerobic tank and the anoxic tank or under certain specific conditions. It reduces nitrate to nitrogen gas and participates in nitrogen removal (denitrification process), especially playing an important role in the nitrogen reflux process in sewage treatment.

[0061] 4. Detection methods used in the following examples and comparative examples:

[0062] (1) COD determination method:

[0063] The potassium dichromate method is the most widely used COD determination method at present and is also one of the standard determination methods. This method uses a strong oxidant (potassium dichromate) to oxidize the organic matter in water under acidic conditions to generate carbon dioxide and water, and at the same time calculates the COD value by measuring the amount of potassium dichromate consumed in the reaction process.

[0064] (2) Determination method and calculation method of ammonia nitrogen removal rate:

[0065] Nessler reagent colorimetric method. Nessler reagent (containing mercury chloride and sodium chloride) reacts with ammonia nitrogen to form a yellow complex. The higher the ammonia nitrogen concentration, the deeper the color. By measuring the absorbance of the sample, the concentration of ammonia nitrogen can be deduced.

[0066] Ammonia nitrogen removal rate (%) = (inlet ammonia nitrogen concentration - outlet ammonia nitrogen concentration) / inlet ammonia nitrogen concentration × 100%

[0067] (3) Determination method and calculation method of total nitrogen removal rate:

[0068] Persulfate digestion method: Persulfate reacts with nitrogen in the water sample at high temperature to generate nitrate, and then measures the absorbance through a specific reagent reaction (such as diazacyclopropene reagent).

[0069] Total nitrogen removal rate (%) = (inlet total nitrogen concentration - outlet total nitrogen concentration) / inlet total nitrogen concentration × 100%

[0070] (4) Determination method of biofilm thickness:

[0071] Scanning Electron Microscope (SEM) Method

[0072] Sample Sampling: Remove the biofilm on the packing and cut it into samples suitable for SEM observation.

[0073] Drying Treatment: Dry the biofilm sample by freezing or air drying to avoid deformation of the membrane structure.

[0074] Gold Plating Treatment: To improve the clarity of the image, the sample needs to be coated with a thin metal film (such as gold or platinum) in a vacuum.

[0075] SEM Observation: Observe the surface morphology of the biofilm under a scanning electron microscope and measure its thickness.

[0076] Example 1: A Method for Promoting Biofilm Attachment on Packing by Adding Signal Molecule C6

[0077] A method for promoting biofilm attachment on packing by adding exogenous signal molecules, the method is as follows:

[0078] Use an SBR reactor with a working volume of 4L, a drainage ratio of 1 / 4, inoculate aerobic activated sludge, and the inoculation amount of activated sludge is: MLSS = 3000mg / L (i.e., 12000mg); and add MBBR suspended packing (K3 packing), and the packing filling ratio is 30% (v / v).

[0079] Set the total hydraulic retention time (HRT) of the SBR reactor to 6h, including 5min of influent, 5h of aeration and stirring, 30min of sedimentation, 5min of effluent, and 20min of stagnant stage.

[0080] Among them, the influent is rural domestic sewage, and its components are: 138mg / L COD, 24.8mg / L NH4 + -N, 2.2mg / L PO4 3- -P, TP 2.6mg / L, TN 38.43mg / L, NO3 - -N 0.54mg / L, NO2 - -N 0.032mg / L.

[0081] The following are the parameters for the operation of the reactor:

[0082] The reactor runs for 4 weeks. The content of the signal molecule C6-HSL added to the influent (rural domestic sewage) is 10 - 100nmol / L. During the operation of the reactor, the concentration of suspended sludge is reduced by sludge discharge every week until the last week of operation in the pure membrane mode. The specific operation during the reactor operation is as follows:

[0083] In the first week of the reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 10 nmol / L;

[0084] In the second week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 2000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 30 nmol / L;

[0085] In the third week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 1000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 50 nmol / L;

[0086] In the fourth week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 0 mg / L, and the content of the signal molecule C6-HSL added to the influent was 100 nmol / L.

[0087] Finally, a reactor operating with a pure membrane was obtained.

[0088] After 4 weeks, the reactor was operated with rural domestic sewage as the influent, and its composition was: 138 mg / L COD, 24.8 mg / L NH4 + -N, 2.2 mg / L PO4 3- -P, TP 2.6 mg / L, TN 38.43 mg / L, NO3 - -N 0.54 mg / L, NO2 - -N 0.032 mg / L;

[0089] The operating parameters of the reactor were:

[0090] The influent time was 5 min; the aeration and agitation time was 300 min; the sedimentation time was 30 min; the effluent time was 5 min; the stagnation stage time was 20 min.

[0091] The sewage after taking out the effluent was tested for the removal rates of COD, ammonia nitrogen and total nitrogen and the thickness of the biofilm.

[0092] After testing, the COD removal rate was 99.6%, the ammonia nitrogen removal rate was 94.2%, the total nitrogen removal rate was 80%, and the biofilm thickness was 190 μm.

[0093] Example 2: Using different rural domestic sewage

[0094] The specific implementation method was the same as that in Example 1, except that the rural domestic sewage was adjusted, and its composition was: 117.5 mg / L COD, 62.3 mg / L NH4 + -N, 1.2 mg / L PO4 3--P, TP 1.75 mg / L, TN 75.6 mg / L, NO3 - -N 0.22 mg / L, NO2 - -N 0.06 mg / L

[0095] For the sewage after water extraction, tests were conducted on the removal rates of COD, ammonia nitrogen, and total nitrogen, as well as the biofilm thickness.

[0096] After testing, the COD removal rate was 98.4%, the ammonia nitrogen removal rate was 92.6%, and the total nitrogen removal rate was 79.4%.

[0097] Example 3: Using different rural domestic sewage

[0098] The specific implementation method is the same as that of Example 1, except that the rural domestic sewage was adjusted, and its components are: 121.4 mg / L COD, 64.8 mg / L NH4 + -N, 2.4 mg / L PO4 3- -P, TP 3.2 mg / L, TN 78.43 mg / L, NO3 - -N 0.32 mg / L, NO2 - -N 0.017 mg / L

[0099] For the sewage after water extraction, tests were conducted on the removal rates of COD, ammonia nitrogen, and total nitrogen, as well as the biofilm thickness.

[0100] After testing, the COD removal rate was 98.6%, the ammonia nitrogen removal rate was 93.2%, and the total nitrogen removal rate was 78.1%.

[0101] Comparative Example 1: Using other signal molecules

[0102] The specific implementation method is the same as that of Example 1, except that the signal molecule C6-HSL was adjusted to C4-HSL or C8-HSL.

[0103] The remaining steps are the same as those in Example 1, and the results are as follows:

[0104] When the signal molecule is C4-HSL, after testing, the COD removal rate was 65.6%, the ammonia nitrogen removal rate was 78.2%, the total nitrogen removal rate was 65.3%, and the biofilm thickness was 82 μm;

[0105] When the signal molecule is C8-HSL, after testing, the COD removal rate was 71.6%, the ammonia nitrogen removal rate was 69.5%, the total nitrogen removal rate was 60.8%, and the biofilm thickness was 78 μm.

[0106] Comparative Example 2: Changing the dosing method of the signal molecule

[0107] 1. The specific implementation is the same as that of Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) is adjusted to be constant at 10 nmol / L, that is, the operation during the reactor operation is adjusted as follows:

[0108] The reactor operation time is 4 weeks. The content of the signal molecule C6-HSL added to the influent (rural domestic sewage) is 10 nmol / L. During the reactor operation, the concentration of suspended sludge is reduced by sludge discharge every week until the last week when it operates in a pure membrane mode. The specific operation during the reactor operation is as follows:

[0109] In the first week of the reactor operation, the concentration of activated sludge in the reactor is 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 10 nmol / L;

[0110] In the second week of the reactor operation, sludge is discharged to make the concentration of activated sludge in the reactor 2000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 10 nmol / L;

[0111] In the third week of the reactor operation, sludge is discharged to make the concentration of activated sludge in the reactor 1000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 10 nmol / L;

[0112] In the fourth week of the reactor operation, sludge is discharged to make the concentration of activated sludge in the reactor 0 mg / L, and the content of the signal molecule C6-HSL added to the influent is 10 nmol / L. The remaining steps are the same as those in Example 1, and the results are as follows:

[0113] After detection, the COD removal rate is 74.6%, the ammonia nitrogen removal rate is 71.7%, the total nitrogen removal rate is 65%, and the biofilm thickness is 60 μm.

[0114] 2. The specific implementation is the same as that of Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) is adjusted to be constant at 30 nmol / L, that is, the operation during the reactor operation is adjusted as follows:

[0115] The reactor operation time is 4 weeks. The content of the signal molecule C6-HSL added to the influent (rural domestic sewage) is 30 nmol / L. During the reactor operation, the concentration of suspended sludge is reduced by sludge discharge every week until the last week when it operates in a pure membrane mode. The specific operation during the reactor operation is as follows:

[0116] In the first week of the reactor operation, the concentration of activated sludge in the reactor is 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 30 nmol / L;

[0117] In the second week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 2000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 30 nmol / L.

[0118] In the third week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 1000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 30 nmol / L.

[0119] In the fourth week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 0 mg / L, and the content of the signal molecule C6-HSL added to the influent was 30 nmol / L.

[0120] The remaining steps were the same as those in Example 1, and the results were as follows:

[0121] After detection, the COD removal rate was 76.2%, the ammonia nitrogen removal rate was 73.1%, the total nitrogen removal rate was 67.2%, and the biofilm thickness was 65 μm.

[0122] 3. The specific implementation method was the same as that in Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) was adjusted to be constant at 50 nmol / L, that is, the operation during the reactor operation was adjusted as follows:

[0123] The reactor operation time was 4 weeks. The content of the signal molecule C6-HSL added to the influent (rural domestic sewage) was 50 nmol / L. During the reactor operation, the concentration of suspended sludge was reduced by discharging sludge every other week until the last week of operation in the pure membrane mode. The specific operation during the reactor operation was as follows:

[0124] In the first week of the reactor operation, the concentration of activated sludge in the reactor was 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 50 nmol / L.

[0125] In the second week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 2000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 50 nmol / L.

[0126] In the third week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 1000 mg / L, and the content of the signal molecule C6-HSL added to the influent was 50 nmol / L.

[0127] In the fourth week of the reactor operation, sludge was discharged to make the concentration of activated sludge in the reactor 0 mg / L, and the content of the signal molecule C6-HSL added to the influent was 50 nmol / L.

[0128] The remaining steps were the same as those in Example 1, and the results were as follows:

[0129] After detection, the COD removal rate was 78.4%, the ammonia nitrogen removal rate was 74.7%, the total nitrogen removal rate was 68.3%, and the biofilm thickness was 67 μm.

[0130] 4. The specific implementation method is the same as that of Example 1, except that the concentration of the signal molecule added to the influent (rural domestic sewage) is adjusted to be constant at 100 nmol / L, that is, the operation during the reactor operation is adjusted as follows:

[0131] The reactor operation time is 4 weeks. The content of the signal molecule C6-HSL added to the influent (rural domestic sewage) is 100 nmol / L. During the reactor operation, the concentration of suspended sludge is reduced by sludge discharge every week until the last week when it operates in a pure membrane mode. The specific operation during the reactor operation is as follows:

[0132] In the first week of the reactor operation, the concentration of activated sludge in the reactor is 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 100 nmol / L;

[0133] In the second week of the reactor operation, sludge discharge is carried out to make the concentration of activated sludge in the reactor 2000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 100 nmol / L;

[0134] In the third week of the reactor operation, sludge discharge is carried out to make the concentration of activated sludge in the reactor 1000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 100 nmol / L;

[0135] In the fourth week of the reactor operation, sludge discharge is carried out to make the concentration of activated sludge in the reactor 0 mg / L, and the content of the signal molecule C6-HSL added to the influent is 100 nmol / L.

[0136] The remaining steps are the same as those in Example 1, and the results are as follows:

[0137] After detection, the COD removal rate was 80.6%, the ammonia nitrogen removal rate was 77.1%, the total nitrogen removal rate was 70.9%, and the biofilm thickness was 75 μm.

[0138] Comparative Example 3: No signal molecule C6-HSL was added

[0139] The specific implementation method is the same as that of Example 1, except that no signal molecule C6-HSL is added to the influent, that is, the operation during the reactor operation is adjusted as follows:

[0140] The reactor operation time is 4 weeks. During the reactor operation, the concentration of suspended sludge is reduced by sludge discharge every week. The specific operation during the reactor operation is as follows:

[0141] In the first week of the reactor operation, the concentration of activated sludge in the reactor is 3000 mg / L;

[0142] In the second week of the reactor operation, sludge discharge was carried out to make the concentration of activated sludge in the reactor 2000 mg / L;

[0143] In the third week of the reactor operation, sludge discharge was carried out to make the concentration of activated sludge in the reactor 1000 mg / L;

[0144] In the fourth week of the reactor operation, sludge discharge was carried out to make the concentration of activated sludge in the reactor 0 mg / L.

[0145] The remaining steps were the same as those in Example 1, and the results were as follows:

[0146] After detection, the COD removal rate was 65.2%, the ammonia nitrogen removal rate was 71.3%, the total nitrogen removal rate was 62.4%, and the biofilm thickness was 93 μm.

[0147] Comparative Example 4: No packing was added

[0148] The specific implementation method was the same as that in Example 1, except that in step (2), no MBBR suspended packing was added, that is, the content "and add MBBR suspended packing (K3 packing), and the filling ratio of MBBR packing is 30% (v / v)" in Example 1 was deleted.

[0149] The remaining steps were the same as those in Example 1, and the results were as follows:

[0150] After detection, the COD removal rate was 82.1%, the ammonia nitrogen removal rate was 70.6%, and the total nitrogen removal rate was 59.8%

[0151] Comparative Example 5: Change the type of feed

[0152] 1. The specific implementation method was the same as that in Example 1, except that adding MBBR suspended packing (K3 packing) was adjusted to adding MBBR suspended packing (K5 packing).

[0153] The remaining steps were the same as those in Example 1, and the results were as follows:

[0154] After detection, the COD removal rate was 85.3%, the ammonia nitrogen removal rate was 80.1%, the total nitrogen removal rate was 70.6%, and the biofilm thickness was 100 μm.

[0155] 2. The specific implementation method was the same as that in Example 1, except that adding MBBR suspended packing (K3 packing) was adjusted to adding MBBR suspended packing (K7 packing).

[0156] The remaining steps were the same as those in Example 1, and the results were as follows:

[0157] After detection, the COD removal rate was 81.2%, the ammonia nitrogen removal rate was 74.8%, the total nitrogen removal rate was 65.1%, and the biofilm thickness was 88 μm.

[0158] Comparative Example 6: Changing the way of adding sludge

[0159] The specific implementation manner is the same as that of Example 1, except that the suspended sludge concentration is always maintained at MLSS = 3000 mg / L, that is, the operation during the reactor operation is adjusted as follows:

[0160] The reactor operation time is 4 weeks. The content of the signal molecule C6-HSL added to the influent (rural domestic sewage) is 10 - 100 nmol / L. During the reactor operation, the suspended sludge concentration is always maintained at MLSS = 3000 mg / L. The operation during the reactor operation is specifically as follows:

[0161] In the first week of the reactor operation, the concentration of activated sludge in the reactor is 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 10 nmol / L;

[0162] In the second week of the reactor operation, sludge is discharged to make the concentration of activated sludge in the reactor 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 30 nmol / L;

[0163] In the third week of the reactor operation, sludge is discharged to make the concentration of activated sludge in the reactor 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 50 nmol / L;

[0164] In the fourth week of the reactor operation, sludge is discharged to make the concentration of activated sludge in the reactor 3000 mg / L, and the content of the signal molecule C6-HSL added to the influent is 100 nmol / L.

[0165] The remaining steps are the same as those of Example 1, and the results are as follows:

[0166] After detection, the COD removal rate is 81.6%, the ammonia nitrogen removal rate is 74.1%, the total nitrogen removal rate is 65.3%, and the biofilm thickness is 65 μm.

[0167] In summary, the above results show that compared with the biofilm thickness in the comparative example, the biofilm in Example 1 with a thickness of 190 μm is more mature. The thickness of the biofilm is usually closely related to the number and activity of microorganisms and the treatment capacity of the reactor. A thicker biofilm provides a larger surface area, which can support more microbial attachment and metabolic activities, especially the degradation of organic matter and nitrogen. The thicker the biofilm, the stronger its treatment capacity usually is. The biofilm in the comparative example is thinner, resulting in a weaker number and degradation capacity of microorganisms, which affects the removal effects of COD, ammonia nitrogen, and total nitrogen. The COD removal rate of 99.6% in Example 1 is also significantly higher than that in the comparative example, and the ammonia nitrogen removal rate of 94.2% is higher than that in the comparative example. In Example 1, due to the more mature biofilm, the number and activity of nitrifying bacteria are stronger, so the removal of ammonia nitrogen can be completed more efficiently. The total nitrogen removal rate of 80% is higher than that in the comparative example. The removal of total nitrogen involves the nitrification process of ammonia nitrogen and the denitrification process of nitrate. The biofilm in Example 1 not only has strong nitrification ability but also can promote the growth and activity of denitrifying bacteria, which helps to further reduce the total nitrogen concentration. However, the biofilm in the comparative example may not support sufficient denitrification process, so the removal efficiency of total nitrogen is low.

[0168] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A method for promoting filler biofilm formation, characterized in that: The method comprises: The reactor was inoculated with activated sludge from aerobic tanks and MBBR suspended fillers were added; sewage was added to the reactor, and the signal molecule C6-HSL was added during the reaction. Biofilm fillers were obtained after the reactor was operated for four weeks; Among them, operating the reactor includes water inlet, aeration and stirring, sedimentation, water outlet, and stagnation; In the first week, the activated sludge concentration was maintained at 2800-3500 mg / L, and 1-10 nmol / L of the signal molecule C6-HSL was added; In the second week, the activated sludge concentration was maintained at 1500-2500 mg / L, and 20-40 nmol / L of the signal molecule C6-HSL was added; In the third week, the activated sludge concentration was maintained at 500-1500 mg / L, and 40-60 nmol / L of the signal molecule C6-HSL was added; In the fourth week, the activated sludge concentration was maintained at 0 mg / L, and 90-110 nmol / L of the signal molecule C6-HSL was added.

2. The method according to claim 1, characterized in that The sewage is rural domestic sewage, and its components include 100-300mg / L COD, 20-100mg / L NH4 + -N, 1-20mg / L PO4 3- -P, 1-20TP mg / L, 20-150mg / L TN, 0-20mg / L NO3 - -N, 0-10mg / L NO2 - -N; Optionally, the MBBR suspended filler is K3 filler.

3. The method according to claim 1, characterized in that When the reactor is running, the water inlet time is 5-10 minutes; the aeration and stirring time is 280-350 minutes; the sedimentation time is 25-60 minutes; the water outlet time is 5-10 minutes; and the stagnation stage time is 15-30 minutes.

4. The method according to claim 1, characterized in that: The inoculum amount of activated sludge in aerobic tanks is 2800-3500 mg / L; Optionally, the inoculation amount MLSS of the activated sludge in the aerobic tank is 3000 mg / L.

5. The method according to claim 1, characterized in that: The amount of MBBR suspended filler added is 20%-50% v / v; Optionally, the MBBR suspension filler is added in an amount of 30% v / v.

6. A method for simultaneously improving the removal rates of COD, ammonia nitrogen and total nitrogen in sewage, characterized in that: A pure membrane reactor is used to treat sewage; the preparation method of the pure membrane reactor is as follows: The reactor was inoculated with activated sludge from aerobic tanks and MBBR suspended fillers; sewage was added to the reactor, and the signal molecule C6-HSL was added during the reaction. After running the reactor for four weeks, a reactor with pure membrane operation was obtained; Among them, operating the reactor includes water inlet, aeration and stirring, sedimentation, water outlet, and stagnation; In the first week, the activated sludge concentration was maintained at 2800-3500 mg / L, and 0-10 nmol / L of the signal molecule C6-HSL was added; In the second week, the activated sludge concentration was maintained at 1500-2500 mg / L, and 20-40 nmol / L of the signal molecule C6-HSL was added; In the third week, the activated sludge concentration was maintained at 500-1500 mg / L, and 40-60 nmol / L of the signal molecule C6-HSL was added; In the fourth week, the activated sludge concentration was maintained at 0 mg / L, and 90-110 nmol / L of the signal molecule C6-HSL was added.

7. The method according to claim 6, characterized in that The sewage is rural domestic sewage, and its components include 100-300mg / L COD, 20-100mg / L NH4 + -N, 1-20mg / L PO4 3- -P, 1-20TP mg / L, 20-150mg / L TN, 0-20mg / L NO3 - -N, 0-10mg / L NO2 - -N.

8. The method according to claim 1, characterized in that When the reactor is running, the water inlet time is 5-10 minutes; the aeration and stirring time is 280-350 minutes; the sedimentation time is 25-60 minutes; the water outlet time is 5-10 minutes; and the stagnation stage time is 15-30 minutes.

9. The method according to claim 1, characterized in that: The inoculum amount of activated sludge in aerobic tanks is 2800-3500 mg / L; Optionally, the inoculum amount MLSS of the activated sludge in the aerobic tank is 3000 mg / L; The amount of MBBR suspended filler added is 20%-50% v / v; Optionally, the MBBR suspension filler is added in an amount of 30% v / v.

10. Use of the method according to any one of claims 1 to 9 in sewage treatment.

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